US20100133102A1

US20100133102A1 - Sensors employing combinatorial artificial receptors

Info

Publication number: US20100133102A1
Application number: US12/261,508
Authority: US
Inventors: Robert E. Carlson
Original assignee: Receptors LLC
Current assignee: Receptors LLC
Priority date: 2003-09-03
Filing date: 2008-10-30
Publication date: 2010-06-03
Also published as: US7469076B2; US20050095698A1

Abstract

The present invention relates to sensors and sensor systems that utilize combinational artificial receptors. Embodiments of the present invention employ combinational artificial receptors in electromagnetic (e.g. optical) and electrochemical sensors.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 10/934,193, filed Sep. 3, 2004, which claims priority to U.S. Provisional Patent Application Nos. 60/499,752, 60/500,081, 60/499,776, 60/499,867, 60/499,965, and 60/499,975 each filed Sep. 3, 2003; and 60/526,511 60/526,699, 60/526,703, 60/526,708, and 60/527,190 each filed Dec. 2, 2003. Each of these patent applications is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to sensors employing artificial receptors, such as combinatorial artificial receptor arrays. The present receptors include heterogeneous and immobilized combinations of building block molecules. In certain embodiments, combinations of 2, 3, 4, or 5 distinct building block molecules immobilized near one another on a support provide molecular structures that can be employed in sensor systems. Sensors employing the present artificial receptors can detect the receptor's ligand.

BACKGROUND

The preparation of artificial receptors that bind ligands like proteins, peptides, carbohydrates, microbes, pollutants, pharmaceuticals, and the like with high sensitivity and specificity is an active area of research. None of the conventional approaches has been particularly successful; achieving only modest sensitivity and specificity mainly due to low binding affinity.
Antibodies, enzymes, and natural receptors generally have binding constants in the 10⁸-10¹²range, which results in both nanomolar sensitivity and targeted specificity. By contrast, conventional artificial receptors typically have binding constants of about 10³to 10⁵, with the predictable result of millimolar sensitivity and limited specificity.
Several conventional approaches are being pursued in attempts to achieve highly sensitive and specific artificial receptors. These approaches include, for example, affinity isolation, molecular imprinting, and rational and/or combinatorial design and synthesis of synthetic or semi-synthetic receptors.
Such rational or combinatorial approaches have been limited by the relatively small number of receptors which are evaluated and/or by their reliance on a design strategy which focuses on only one building block, the homogeneous design strategy. Common combinatorial approaches form microarrays that include 10,000 or 100,000 distinct spots on a standard microscope slide. However, such conventional methods for combinatorial synthesis provide a single molecule per spot. Employing a single building block in each spot provides only a single possible receptor per spot. Synthesis of thousands of building blocks would be required to make thousands of possible receptors.
Further, these conventional approaches are hampered by the currently limited understanding of the principals which lead to efficient binding and the large number of possible structures for receptors, which makes such an approach problematic.
There remains a need for methods for detecting ligands and for detecting compounds that disrupt one or more binding interactions.

SUMMARY

An embodiment of a sensor system includes a waveguide, a detection system that can be operatively coupled to the waveguide, and a working artificial receptor. The waveguide can be operatively configured with respect to the working artificial receptor such that the waveguide is capable of receiving light that from the viscininty of the working artificial receptor. The detection system can be configured to detect light from the waveguide.
An embodiment of an electrochemical sensing system includes a working electrode, a reference electrode, and a working artificial receptor that is coupled to the working electrode. The sensing system can be configured to generate a sensing signal.
An embodiment of an electrochemical sensing system includes a field effect transistor, and a working artificial receptor that is coupled to the field effect transistor. A signal can be generated by the field effect transistor when a test ligand binds to a working artificial receptor.
An embodiment of sensor system includes a detector and a working artificial receptor that is coupled to the detector. The detector system can be configured to detect the presence of a test ligand bound to the working artificial receptor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates two dimensional representations of an embodiment of a receptor according to the present invention that employs 4 different building blocks to make a ligand binding site.

FIG. 2 schematically illustrates two and three dimensional representations of an embodiment of a molecular configuration of 4 building blocks, each building block including a recognition element, a framework, and a linker coupled to a support (immobilization/anchor).

FIG. 3 schematically illustrates an embodiment of the present methods and artificial receptors employing shuffling and exchanging building blocks.

FIG. 4 is a schematic drawing of an electromagnetic radiation (light) sensor system that includes a wave guide.

FIG. 5 is a schematic drawing of an optical sensor system that includes a plurality of fibers.

FIG. 6 is a schematic drawing of an electrochemical sensor system.

FIG. 7 is a schematic drawing of an electrochemical sensor system that employs a membrane to which the present artificial receptors can be coupled.

FIG. 8 is a schematic drawing of a sensor system that uses both optical and electrochemical sensors.

FIG. 9 is a cross-sectional view of a microwell and a protrusion.

FIG. 10 is an exemplary illustration of a pattern detected by a sensor array.

FIG. 11 is a schematic illustration of a fiber bundle to which the present artificial receptors can be coupled.

FIGS. 12A-12D are schematic illustrations of field effect transistor devices to which the present artificial receptors can be bound.

FIG. 13 schematically illustrates an embodiment of a method for evaluating candidate artificial receptors for binding to a test ligand, such as a molecule or cell.

FIG. 14 schematically illustrates an embodiment of the present method employing an array of candidate artificial receptors.

FIG. 15 schematically illustrates certain binding patterns on an array of working artificial receptors.

FIG. 16 schematically illustrates an embodiment of a method for developing a method and system for detecting a test ligand.

FIG. 17 schematically illustrates an embodiment of a method for detecting an agent that disrupts a binding interaction of a target molecule.

FIG. 18 schematically illustrates an embodiment of a method for detecting an agent that disrupts a binding interaction of a complex including a target molecule.

FIG. 19 schematically illustrates an embodiment of a method of employing the present artificial receptors to produce or as an affinity support.

FIG. 20 schematically illustrates a candidate disruptor disrupting a protein:protein complex.

FIG. 21 schematically illustrates evaluating an array of candidate artificial receptors for binding of a test ligand and selecting one or more working artificial receptors for binding or operating on a test ligand.

FIG. 22 schematically illustrates identification of a lead artificial receptor from among candidate artificial receptors.

FIG. 23 schematically illustrates a false color fluorescence image of a labeled microarray according to an embodiment of the present invention.

FIG. 24 schematically illustrates a two dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding phycoerythrin.

FIG. 25 schematically illustrates a three dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding phycoerythrin.

FIG. 26 schematically illustrates a two dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding a fluorescent derivative of ovalbumin.

FIG. 27 schematically illustrates a three dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding a fluorescent derivative of ovalbumin.

FIG. 28 schematically illustrates a two dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding a fluorescent derivative of bovine serum albumin.

FIG. 29 schematically illustrates a three dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding a fluorescent derivative of bovine serum albumin.

FIG. 30 schematically illustrates a two dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding an acetylated horseradish peroxidase.

FIG. 31 schematically illustrates a three dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding an acetylated horseradish peroxidase.

FIG. 32 schematically illustrates a two dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding a TCDD derivative of horseradish peroxidase.

FIG. 33 schematically illustrates a three dimensional plot of data obtained for candidate artificial receptors contacted with and/or binding a TCDD derivative of horseradish peroxidase.

FIG. 34 schematically illustrates a subset of the data illustrated in FIG. 25.

FIG. 35 schematically illustrates a subset of the data illustrated in FIG. 25.

FIG. 36 schematically illustrates a subset of the data illustrated in FIG. 25.

FIG. 37 schematically illustrates a correlation of binding data for phycoerythrin against logP for the building blocks making up the artificial receptor.

FIG. 38 schematically illustrates a correlation of binding data for phycoerythrin against logP for the building blocks making up the artificial receptor.

FIG. 39 schematically illustrates a two dimensional plot comparing data obtained for candidate artificial receptors contacted with and/or binding phycoerythrin to data obtained for candidate artificial receptors contacted with and/or binding a fluorescent derivative of bovine serum albumin.

FIGS. 40, 41, and 42 schematically illustrate subsets of data from FIGS. 25, 29, and 27, respectively, and demonstrate that the array of artificial receptors according to the present invention yields receptors distinguished between three analytes, phycoerythrin, bovine serum albumin, and ovalbumin.

FIG. 43 schematically illustrates a gray scale image of the fluorescence signal from a scan of a control plate which was prepared by washing off the building blocks with organic solvent before incubation with the test ligand.

FIG. 44 schematically illustrates a gray scale image of the fluorescence signal from a scan of an experimental plate which was incubated with 1.0 μg/ml Cholera Toxin B at 23° C.

FIG. 45 schematically illustrates a gray scale image of the fluorescence signal from a scan of an experimental plate which was incubated with 1.0 μg/ml Cholera Toxin B at 3° C.

FIG. 46 schematically illustrates a gray scale image of the fluorescence signal from a scan of an experimental plate which was incubated with 1.0 μg/ml Cholera Toxin B at 43° C.

FIGS. 47-49 schematically illustrate plots of the fluorescence signals obtained from the candidate artificial receptors illustrated in FIGS. 44-46.

FIG. 50 schematically illustrate plots of the fluorescence signals obtained from the combinations of building blocks employed in the present studies, when those building blocks are covalently linked to the support. Binding was conducted at 23° C.

FIG. 51 schematically illustrates a graph of the changes in fluorescence signal from individual combinations of building blocks at 4° C., 23° C., or 44° C.

FIG. 52 schematically illustrates a graph of the changes in fluorescence signal from individual combinations of building blocks at 4° C., 23° C., or 44° C.

FIG. 53 schematically illustrates the data presented in FIG. 51 (lines marked A) and the data presented in FIG. 52 (lines marked B).

FIG. 54 schematically illustrates a graph of the fluorescence signal at 44° C. divided by the signal at 23° C. against the fluorescence signal obtained from binding at 23° C. for the artificial receptors with reversibly immobilized receptors.

FIG. 55 illustrates fluorescence signals produced by binding of cholera toxin to a microarray of the present candidate artificial receptors followed by washing with buffer in an experiment reported in Example 4.

FIG. 56 illustrates the fluorescence signals due to cholera toxin binding that were detected upon competition with GM1 OS (0.34 μM) in an experiment reported in Example 4.

FIG. 57 illustrates the ratio of the amount bound in the absence of GM1 OS to the amount bound in competition with GM1 OS (0.34 μM) in an experiment reported in Example 4.

FIG. 58 illustrates fluorescence signals produced by binding of cholera toxin to a microarray of the present candidate artificial receptors followed by washing with buffer in an experiment reported in Example 4 and for comparison with competition experiments using 5.1 μM GM1 OS.

FIG. 59 illustrates the fluorescence signals due to cholera toxin binding that were detected upon competition with GM1 OS (5.1 μM) in an experiment reported in Example 4.

FIG. 60 illustrates the ratio of the amount bound in the absence of GM1 OS to the amount bound in competition with GM1 OS (5.1 μM) in an experiment reported in Example 4.

FIG. 61 illustrates the fluorescence signals produced by binding of cholera toxin to the microarray of candidate artificial receptors alone and in competition with each of the three concentrations of GM1 in the experiment reported in Example 5.

FIG. 62 illustrates the ratio of the amount bound in the absence of GM1 OS to the amount bound upon competition with GM1 for the low concentration of GM1 employed in Example 5.

FIG. 63 illustrates the fluorescence signals produced by binding of cholera toxin to the microarray of candidate artificial receptors without pretreatment with GM1 in the experiment reported in Example 6.

FIGS. 64-66 illustrate the fluorescence signals produced by binding of cholera toxin to the microarray of candidate artificial receptors with pretreatment with GM1 (100 μg/ml, 10 μg/ml, and 1 μg/ml GM1, respectively) in the experiment reported in Example 6.

FIG. 67 illustrates the ratio of the amount bound in the presence of 1 μg/ml GM1 to the amount bound in the absence of GM1 in the experiment reported in Example 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Definitions

As used herein, the term “peptide” refers to a compound including two or more amino acid residues joined by amide bond(s).
As used herein, the terms “polypeptide” and “protein” refer to a peptide including more than about 20 amino acid residues connected by peptide linkages.
As used herein, the term “proteome” refers to the expression profile of the proteins of an organism, tissue, organ, or cell. The proteome can be specific to a particular status (e.g., development, health, etc.) of the organism, tissue, organ, or cell.
As used herein, the term “support” refers to a solid support that is, typically, macroscopic.
As used herein, the term scaffold refers to a molecular scale structure to which a plurality of building blocks can covalently bind.
Reversibly immobilizing building blocks on a support couples the building blocks to the support through a mechanism that allows the building blocks to be uncoupled from the support without destroying or unacceptably degrading the building block or the support. That is, immobilization can be reversed without destroying or unacceptably degrading the building block or the support. In an embodiment, immobilization can be reversed with only negligible or ineffective levels of degradation of the building block or the support. Reversible immobilization can employ readily reversible covalent bonding or noncovalent interactions. Suitable noncovalent interactions include interactions between ions, hydrogen bonding, van der Waals interactions, and the like. Readily reversible covalent bonding refers to covalent bonds that can be formed and broken under conditions that do not destroy or unacceptably degrade the building block or the support.
A combination of building blocks immobilized on, for example, a support can be a candidate artificial receptor, a lead artificial receptor, or a working artificial receptor. That is, a heterogeneous building block spot on a slide or a plurality of building blocks coated on a tube or well can be a candidate artificial receptor, a lead artificial receptor, or a working artificial receptor. A candidate artificial receptor can become a lead artificial receptor, which can become a working artificial receptor.
As used herein the phrase “candidate artificial receptor” refers to an immobilized combination of building blocks that can be tested to determine whether or not a particular test ligand binds to that combination. In an embodiment, the combination includes one or more reversibly immobilized building blocks. In an embodiment, the candidate artificial receptor can be a heterogeneous building block spot on a slide or a plurality of building blocks coated on a tube or well.
As used herein the phrase “lead artificial receptor” refers to an immobilized combination of building blocks that binds a test ligand at a predetermined concentration of test ligand, for example at 10, 1, 0.1, or 0.01 μg/ml, or at 1, 0.1, or 0.01 ng/ml. In an embodiment, the combination includes one or more reversibly immobilized building blocks. In an embodiment, the lead artificial receptor can be a heterogeneous building block spot on a slide or a plurality of building blocks coated on a tube or well.
As used herein the phrase “working artificial receptor” refers to a combination of building blocks that binds a test ligand with a selectivity and/or sensitivity effective for categorizing or identifying the test ligand. That is, binding to that combination of building blocks describes the test ligand as belonging to a category of test ligands or as being a particular test ligand. A working artificial receptor can, for example, bind the ligand at a concentration of, for example, 100, 10, 1, 0.1, 0.01, or 0.001 ng/ml. In an embodiment, the combination includes one or more reversibly immobilized building blocks. In an embodiment, the working artificial receptor can be a heterogeneous building block spot on a slide or a plurality of building blocks coated on a tube, well, slide, or other support or on a scaffold.
As used herein the phrase “working artificial receptor complex” refers to a plurality of artificial receptors, each a combination of building blocks, that binds a test ligand with a pattern of selectivity and/or sensitivity effective for categorizing or identifying the test ligand. That is, binding to the several receptors of the complex describes the test ligand as belonging to a category of test ligands or as being a particular test ligand. The individual receptors in the complex can each bind the ligand at different concentrations or with different affinities. For example, the individual receptors in the complex each bind the ligand at concentrations of 100, 10, 1, 0.1, 0.01 or 0.001 ng/ml. In an embodiment, the combination includes one or more reversibly immobilized building blocks. In an embodiment, the working artificial receptor complex can be a plurality of heterogeneous building block spots or regions on a slide; a plurality of wells, each coated with a different combination of building blocks; or a plurality of tubes, each coated with a different combination of building blocks.
As used herein, the phrase “significant number of candidate artificial receptors” refers to sufficient candidate artificial receptors to provide an opportunity to find a working artificial receptor, working artificial receptor complex, or lead artificial receptor. As few as about 100 to about 200 candidate artificial receptors can be a significant number for finding working artificial receptor complexes suitable for distinguishing two proteins (e.g., cholera toxin and phycoerythrin). In other embodiments, a significant number of candidate artificial receptors can include about 1,000 candidate artificial receptors, about 10,000 candidate artificial receptors, about 100,000 candidate artificial receptors, or more.
Although not limiting to the present invention, it is believed that the significant number of candidate artificial receptors required to provide an opportunity to find a working artificial receptor may be larger than the significant number required to find a working artificial receptor complex. Although not limiting to the present invention, it is believed that the significant number of candidate artificial receptors required to provide an opportunity to find a lead artificial receptor may be larger than the significant number required to find a working artificial receptor. Although not limiting to the present invention, it is believed that the significant number of candidate artificial receptors required to provide an opportunity to find a working artificial receptor for a test ligand with few features may be more than for a test ligand with many features.
As used herein, the term “building block” refers to a molecular component of an artificial receptor including portions that can be envisioned as or that include one or more linkers, one or more frameworks, and one or more recognition elements. In an embodiment, the building block includes a linker, a framework, and one or more recognition elements. In an embodiment, the linker includes a moiety suitable for reversibly immobilizing the building block, for example, on a support, surface or lawn. The building block interacts with the ligand.
As used herein, the term “linker” refers to a portion of or functional group on a building block that can be employed to or that does (e.g., reversibly) couple the building block to a support, for example, through covalent link, ionic interaction, electrostatic interaction, or hydrophobic interaction.
As used herein, the term “framework” refers to a portion of a building block including the linker or to which the linker is coupled and to which one or more recognition elements are coupled.
As used herein, the term “recognition element” refers to a portion of a building block coupled to the framework but not covalently coupled to the support. Although not limiting to the present invention, the recognition element can provide or form one or more groups, surfaces, or spaces for interacting with the ligand.
As used herein, the phrase “plurality of building blocks” refers to two or more building blocks of different structure in a mixture, in a kit, or on a support or scaffold. Each building block has a particular structure, and use of building blocks in the plural, or of a plurality of building blocks, refers to more than one of these particular structures. Building blocks or plurality of building blocks does not refer to a plurality of molecules each having the same structure.
As used herein, the phrase “combination of building blocks” refers to a plurality of building blocks that together are in a spot, region, or a candidate, lead, or working artificial receptor. A combination of building blocks can be a subset of a set of building blocks. For example, a combination of building blocks can be one of the possible combinations of 2, 3, 4, 5, or 6 building blocks from a set of N (e.g., N=10-200) building blocks.
As used herein, the phrases “homogenous immobilized building block” and “homogenous immobilized building blocks” refer to a support or spot having immobilized on or within it only a single building block.
As used herein, the phrase “activated building block” refers to a building block activated to make it ready to form a covalent bond to a functional group, for example, on a support. A building block including a carboxyl group can be converted to a building block including an activated ester group, which is an activated building block. An activated building block including an activated ester group can react, for example, with an amine to form a covalent bond.
As used herein, the term “naïve” used with respect to one or more building blocks refers to a building block that has not previously been determined or known to bind to a test ligand of interest. For example, the recognition element(s) on a naïve building block has not previously been determined or known to bind to a test ligand of interest. A building block that is or includes a known ligand (e.g., GM1) for a particular protein (test ligand) of interest (e.g., cholera toxin) is not naïve with respect to that protein (test ligand).
As used herein, the term “immobilized” used with respect to building blocks coupled to a support refers to building blocks being stably oriented on the support so that they do not migrate on the support or release from the support. Building blocks can be immobilized by covalent coupling, by ionic interactions, by electrostatic interactions, such as ion pairing, or by hydrophobic interactions, such as van der Waals interactions.
As used herein a “region” of a support, tube, well, or surface refers to a contiguous portion of the support, tube, well, or surface. Building blocks coupled to a region can refer to building blocks in proximity to one another in that region.
As used herein, a “bulky” group on a molecule is larger than a moiety including 7 or 8 carbon atoms.
As used herein, a “small” group on a molecule is hydrogen, methyl, or another group smaller than a moiety including 4 carbon atoms.
As used herein, the term “lawn” refers to a layer, spot, or region of functional groups on a support, for example, at a density sufficient to place coupled building blocks in proximity to one another. The functional groups can include groups capable of forming covalent, ionic, electrostatic, or hydrophobic interactions with building blocks.
As used herein, the term “alkyl” refers to saturated aliphatic groups, including straight-chain alkyl groups, branched-chain alkyl groups, cycloalkyl (alicyclic) groups, alkyl substituted cycloalkyl groups, and cycloalkyl substituted alkyl groups. In certain embodiments, a straight chain or branched chain alkyl has 30 or fewer carbon atoms in its backbone (e.g., C₁-C₁₂for straight chain, C₁-C₆for branched chain). Likewise, cycloalkyls can have from 3-10 carbon atoms in their ring structure, for example, 5, 6 or 7 carbons in the ring structure.
The term “alkyl” as used herein refers to both “unsubstituted alkyls” and “substituted alkyls”, the latter of which refers to alkyl moieties having substituents replacing a hydrogen on one or more carbons of the hydrocarbon backbone. Such substituents can include, for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, an ester, a formyl, or a ketone), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxyl, a phosphoryl, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aryl alkyl, or an aromatic or heteroaromatic moiety. The moieties substituted on the hydrocarbon chain can themselves be substituted, if appropriate. For example, the substituents of a substituted alkyl can include substituted and unsubstituted forms of the groups listed above.
The phrase “aryl alkyl”, as used herein, refers to an alkyl group substituted with an aryl group (e.g., an aromatic or heteroaromatic group).
As used herein, the terms “alkenyl” and “alkynyl” refer to unsaturated aliphatic groups analogous in length and optional substitution to the alkyls groups described above, but that contain at least one double or triple bond respectively.
The term “aryl” as used herein includes 5-, 6- and 7-membered single-ring aromatic groups that may include from zero to four heteroatoms, for example, benzene, pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, pyridazine and pyrimidine, and the like. Those aryl groups having heteroatoms in the ring structure may also be referred to as “aryl heterocycles” or “heteroaromatics”. The aromatic ring can be substituted at one or more ring positions with such substituents such as those described above for alkyl groups. The term “aryl” also includes polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings (the rings are “fused rings”) wherein at least one of the rings is aromatic, e.g., the other cyclic ring(s) can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls and/or heterocyclyls.
As used herein, the terms “heterocycle” or “heterocyclic group” refer to 3- to 12-membered ring structures, e.g., 3- to 7-membered rings, whose ring structures include one to four heteroatoms. Heterocyclyl groups include, for example, thiophene, thianthrene, furan, pyran, isobenzofuran, chromene, xanthene, phenoxathiin, pyrrole, imidazole, pyrazole, isothiazole, isoxazole, pyridine, pyrazine, pyrimidine, pyridazine, indolizine, isoindole, indole, indazole, purine, quinolizine, isoquinoline, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, carbazole, carboline, phenanthridine, acridine, pyrimidine, phenanthroline, phenazine, phenarsazine, phenothiazine, furazan, phenoxazine, pyrrolidine, oxolane, thiolane, oxazole, piperidine, piperazine, morpholine, lactones, lactams such as azetidinones and pyrrolidinones, sultams, sultones, and the like. The heterocyclic ring can be substituted at one or more positions with such substituents such as those described for alkyl groups.
As used herein, the term “heteroatom” as used herein means an atom of any element other than carbon or hydrogen, such as nitrogen, oxygen, sulfur and phosphorous.

Overview of the Artificial Receptor

FIG. 1 schematically illustrates an embodiment employing 4 distinct building blocks in a spot on a microarray to make a ligand binding site. This Figure illustrates a group of 4 building blocks at the corners of a square forming a unit cell. A group of four building blocks can be envisioned as the vertices on any quadrilateral. FIG. 1 illustrates that spots or regions of building blocks can be envisioned as multiple unit cells, in this illustration square unit cells. Groups of unit cells of four building blocks in the shape of other quadrilaterals can also be formed on a support.
Each immobilized building block molecule can provide one or more “arms” extending from a “framework” and each can include groups that interact with a ligand or with portions of another immobilized building block. FIG. 2 illustrates that combinations of four building blocks, each including a framework with two arms (called “recognition elements”), provides a molecular configuration of building blocks that form a site for binding a ligand. Such a site formed by building blocks such as those exemplified below can bind a small molecule, such as a drug, metabolite, pollutant, or the like, and/or can bind a larger ligand such as a macromolecule or microbe.
The present artificial receptors can include building blocks reversibly immobilized on a support or surface. Reversing immobilization of the building blocks can allow movement of building blocks to a different location on the support or surface, or exchange of building blocks onto and off of the surface. For example, the combinations of building blocks can bind a ligand when reversibly coupled to or immobilized on the support. Reversing the coupling or immobilization of the building blocks provides opportunity for rearranging the building blocks, which can improve binding of the ligand. Further, the present invention can allow for adding additional or different building blocks, which can further improve binding of a ligand.
FIG. 3 schematically illustrates an embodiment employing an initial artificial receptor surface (A) with four different building blocks on the surface, which are represented by shaded shapes. This initial artificial receptor surface (A) undergoes (1) binding of a ligand to an artificial receptor and (2) shuffling the building blocks on the receptor surface to yield a lead artificial receptor (B). Shuffling refers to reversing the coupling or immobilization of the building blocks and allowing their rearrangement on the receptor surface. After forming a lead artificial receptor, additional building blocks can be (3) exchanged onto and/or off of the receptor surface (C). Exchanging refers to building blocks leaving the surface and entering a solution contacting the surface and/or building blocks leaving a solution contacting the surface and becoming part of the artificial receptor. The additional building blocks can be selected for structural diversity (e.g., randomly) or selected based on the structure of the building blocks in the lead artificial receptor to provide additional avenues for improving binding. The original and additional building blocks can then be (4) shuffled and exchanged to provide higher affinity artificial receptors on the surface (D).

Sensors Employing the Artificial Receptors

The present artificial receptors can be configured in sensors, sensor systems, and sensing methods. For example, a sensor system can be can be configured to detect a test ligand in a sample or an environment based upon a signal received from a sensor operatively configured to detect a test ligand that binds to the present artificial receptor.
In an embodiment, the sensor system includes an optical sensor system. The optical sensor system can include a waveguide, a detection system operatively coupled to the waveguide, and an artificial receptor that binds a test ligand of interest (e.g., a working artificial receptor). The waveguide can be operatively configured with respect to the working artificial receptor such that the waveguide can receive an optical signal (e.g., fluorescence, luminescence, or absorbance) from the working artificial receptor.
In an embodiment, the sensor system includes an electrochemical sensor system. An electrochemical sensing system can include a transducer (e.g., an electrode or CHEMFET), a detection system operatively coupled to the transducer, and an artificial receptor that binds a test ligand of interest (e.g., a working artificial receptor). The transducer can be operatively configured with respect to the working artificial receptor such that the transducer can detect changes in electrical charge, potential, or current (e.g., conductance, capacitance, or impedence) from the working artificial receptor. In an embodiment, the transducer includes at least one electrode. An electrochemical sensing system can include a working electrode, a reference electrode, and a working artificial receptor. In an embodiment, the present artificial receptors can be coupled to the working electrode. In an embodiment, the present artificial receptors can be coupled to a membrane that is configured between the working electrode and the reference electrode. In an embodiment, the working electrode and reference electrode can be conventional electrodes. In an embodiment, the working electrode and reference electrode can be a source and a drain of a field effect transistor.
A sample expected of containing a test ligand can be brought into contact with an artificial receptor by a variety of mechanisms. For example, the sample can be carried in a stream of air or an aerosol. The sample can be a liquid. In an embodiment, it can be desirable to increase the surface area to which present artificial receptors are coupled to provide enhanced detection of a test ligand in a gaseous or liquid flow. In an embodiment, a flow can be received through a foamed support substance, such as an aerogel to which present artificial receptors can be coupled.

Supporting Environments for the Artificial Receptors

The present artificial receptors can be supported in sensors or sensors systems in a variety of configurations in or on a variety of support materials. For example, the present artificial receptors can be supported in solid, gel, and foam environments. To accommodate various sensing systems, the present artificial receptors can be configured in an environment that conducts electrical currents, light, and/or other electromagnetic radiation.
In an embodiment, present artificial receptors can be located at or near a distal surface of a fiber, such an optical fiber. The distal surface can, for example, be an end of an optical fiber. In an embodiment, the present artificial receptors can be bonded or otherwise coupled to the distal surface on the fiber. For example, the present artificial receptors can be coupled directly to the end of a fiber. In an embodiment, the present artificial receptors can be coupled, embedded, or otherwise configured to a support material or substrate that can be coupled to the fiber. In an embodiment, the present artificial receptors can be located near the end of a fiber without being coupled to the fiber. For example, the present artificial receptors can be coupled to or suspended in a target object or substrate that can be configured to be detectable by the fiber. In an embodiment, a receptor-supporting material can be layered on the object or substrate. In an embodiment, the target object itself can be the support for the receptor, i.e. the object or substrate can be formed from the material to which the present artificial receptors can be coupled.
In an embodiment, a sol-gel can be a support for the present artificial receptors. For example, the present artificial receptors can be coupled to or suspended in a sol-gel that can be coupled to a fiber or electrode. The sol-gel process involves the transition of a system from a liquid “sol” into a solid “gel” phase. Through a sol-gel process, it is possible to fabricate ceramic or glass materials in a wide variety of forms. Dopants can be added to alter the glass properties. For example, ultra-fine or spherical shaped powders, thin film coatings, ceramic fibers, microporous inorganic membranes, monolithic ceramics and glasses, or extremely porous aerogel materials can be developed using a sol gel process. In one process, a sol gel is a colloidal suspension of silica particles that is gelled to form a solid. The resulting porous gel can be chemically purified and consolidated at high temperatures into high purity silica.
A sol-gel can be coated or otherwise applied to an object, or alternatively formed into an object itself. In an embodiment, a sol-gel can be applied to the surface of a fiber by dip coating, and the current artificial receptors can be coupled to the sol gel. In an embodiment, the present artificial receptors can be coupled to a sol gel substrate that is configured to be detectable by a fiber but is not connected to the fiber. For example, sol gel can be applied to a plate or other substrate, and the optical fiber can be aligned to detect a portion of the plate.
In addition to dip-coating, sol-gel can be applied through other processes such as spraying, casting, and spin coating. Other forms of sol gels, such as aerogels, powders, and thin films formed from xerogels can also be configured for use with the present artificial receptors. Sol gel processes are described in U.S. Pat. No. 5,774,603. Dual-layer sensors and sensors that utilize aerosol-generated sol gels are described in U.S. Pat. No. 6,016,689.
In an embodiment, a microsphere (or “bead”) can be configured as a support for the present artificial receptors. A sensor incorporating an optical fiber and a solid porous inorganic microsphere is described in U.S. Pat. No. 5,496,997. Microspheres having a polymeric shell with consistent shell thickness are described in U.S. Pat. No. 6,720,007. Microspheres are also discussed in U.S. Pat. Nos. 6,327,410 and 6,266,459 and Published U.S. Patent Application Nos. 20030016897, 20020122612, 20010029049. A plurality or multiplicity of microspheres can be configured to allow for multiplexed detection (binding of multiple analytes on multiple sets of coated beads). The present artificial receptors can also be incorporated into a nanosphere.
In an embodiment, a support, such as a microsphere can be encoded with an optical signature. While other support environments and structures can be encoded, microspheres will be referenced herein for descriptive purposes. A structure such as a microsphere can be encoded, for example, by use of a dye that can be entrapped within the bead. The dye can, for example, be a fluorescent dye. The dye can also be a chromophore or phosphor, or other optically-detectable substance. In an embodiment, two or more dyes can be used to provide a multi-parametric code. In an embodiment, the code can correspond to a chemical functionality or sensitivity that is associated with the microsphere. Fiber optic sensors with encoded microspheres are described in U.S. Pat. No. 6,023,540.
In an embodiment, the present artificial receptors can be configured for use in conjunction with a capillary tube. For example, an optical fiber (or an electrode) can be supported within a capillary tube. A fluid sample can be introduced into the space between the fiber (or electrode) and the tube. A fluid can be drawn into and supported in the space by capillary action. The present artificial receptors can be coupled to the optical fiber (or electrode), the capillary tube, or an object in the capillary tube, and configured to detect a test ligand in the fluid sample. A fluorescent immunoassay employing an optical fiber in a capillary tube is described in U.S. Pat. No. 4,447,546.
The present artificial receptors can also be configured in a cavity. As used herein, cavity is intended to refer to a microwell, pit, cavity, depression, void, or similar structure. For purposes of the present discussion, a microwell will be described, although the present application also applies to other forms of cavities. In an embodiment, a microwell can be formed in an end of an optical fiber. A microwell can also be formed on a substrate that can be configured to be detectable by an optical fiber. Microwell-based sensors are described in U.S. Pat. Nos. 6,667,159, 6,377,721, and 6,210,910. In an embodiment, a plurality of microwells can be formed at the distal end of individual fibers within a randomly-ordered addressable sensor arrays, as further described in U.S. Pat. No. 6,667,159.
In an embodiment, a microwell receives a bead, to which receptors can be coupled. In an embodiment, the microwell and bead can be configured on an end surface of a fiber. In an embodiment, the bead and depression structure can mimic the shape of mammalian taste buds. The bead can, for example, be constructed of a polymer.
FIG. 9 shows a cross-section of a depression 730 in a substance 720 which can be, for example, a substrate, waveguide, or electrode. The depression can be, for example, a microwell. A protrusion 740, which can be a sphere or bead, can reside in the depression 730. The present working electrodes 710 can be coupled to the protrusion 740. In an embodiment, the present working electrodes can be coupled to the depression surface.
In an embodiment, an array of micron-sized wells can be formed at the distal tip of an optical imaging fiber, and the present artificial receptors can be coupled in the wells. In an embodiment, a well can be created using a wet-etch process. Where there are differences in core and clad etch rates, a well can be created between core and clad material. For example, where fiber cores etch faster than the cladding, the core etches away to produce a well that is defined by the remaining clad. In an embodiment, the present artificial receptors can be coupled to the cells. In an embodiment, a living cell can be received into a well and the present artificial receptors can be configured to detect the presence and/or behavior of the living cells.
In an embodiment, cells can be plated onto a fiber and the present artificial receptors can be configured to facilitate detection of the cells.
In an embodiment, sensors employing the present artificial receptors can be configured to make optical analytical measurements at remote locations. U.S. Pat. No. 5,814,524 describes an apparatus that employs an imaging fiber comprising a fiber optic array and a Gradient Index lens and utilizes a remotely-positioned solid substrate having light energy absorbing indicator ligands on an external surface for reactive contact with individual species of analytes when present in a fluid sample.
The present artificial receptors can also be supported in a carbon paste. In an embodiment, a hybrid optical/electrochemical sensor can be provided, where the carbon paste can be electrically coupled to a circuit that can be configured to detect electrical behaviors or properties of the sample/and or receptors.
The present artificial receptors can also be configured in a microchannel. In an embodiment, a microchannel includes a longitudinal recess on a surface and the present artificial receptors can be coupled to the recessed surface and configured to detect a test ligand in a fluid in the microchannel.
The present artificial receptors can also be supported on a membrane. In an embodiment, the present artificial receptors can be coupled to a membrane which can be placed in front of the tip of an optical fiber. In an embodiment, the membrane can be removable. In an embodiment, the present artificial receptor can be coupled to a membrane that is positioned between two electrodes in an electrochemical sensor.
In an embodiment, the present artificial receptors can be coupled to a hexamethyldisiloxane plasma-polymerized film.
Other materials, including molecularly imprinted polymers and zeolite, can be configured as a support for the present artificial receptors. The present artificial receptors can also be configured for use with disposable screen printing technology.

Fiber Optic Sensors

Fiber optic technology can be utilized with the present artificial receptors. Fiber optic systems can be configured to allow for detection of modulation in the quality or quantity of electromagnetic radiation, such as visible light, infrared radiation, or ultraviolet radiation. For example, the intensity (energy), polarization state, phase and wavelength of radiation can be detected and measured. Embodiments of fiber optic-based sensors are described in U.S. Pat. Nos. 5,690,894 and 6,680,206.
A fiber optic detection system can be configured with a fiber arranged to detect radiation and/or optical properties in the vicinity of the present artificial receptors. Embodiments of fiber optic sensing systems can be designed to provide remote, distributed and multiplexed sensing. An embodiment of an optical sensing system that uses receptors is shown and described in U.S. Pat. No. 5,512,490. In an embodiment, sensors can be employed with micromechanical systems. Sensors can also be designed to operate in hostile and hazardous environments. In an embodiment, a fiber can be covered by a protective cladding layer to protect the fiber.
Fiber optic fibers can be interfaced with filters and light sources to facilitate detection of particular properties or behaviors of a substance that contains the present artificial receptors or is coupled to the present artificial receptors. The presence of a test ligand coupled to a receptor in a sample can be detected, for example, by detection of the emission, absorption, or refractive index of the sample. Detectors can be configured to measure a variety of types of radiation, including, for example, white light, ultraviolet light or fluorescence. In an embodiment, an emitter and a receiver can be coupled to separate fibers and the reflected, refracted, or conducted light (or other radiation) can be detected. Other sources of radiation can also be used.
FIG. 4 is a schematic illustration of an embodiment of a sensor system 200 that can be configured to detect an optical signal. The present artificial receptors 210 can be coupled to a substrate 220. An light source 230, such as a laser or lamp, directs light toward the artificial receptors. A waveguide 240 can be configured to detect electromagnetic radiation, i.e. light. The waveguide 240 can be configured to detect, for example, reflected radiation, conducted radiation, or fluorescent radiation. The waveguide can be, for example, a planar waveguide. A fiber 250, for example an optical fiber, can be coupled to the waveguide 240 and to an electromagnetic detection system 260, such as a charge coupled device (CCD). The detection system can be coupled to a processing system 270, such as a computer system, which can be configured to process and save data received from the detection system. Alternatively, the detection system can be configured to be directly present or save data, without use of a separate processing system.
FIG. 5 shows an embodiment of a sensing system 300 in which a fiber 320 can be configured for use as a waveguide. As shown in FIG. 5, multiple fibers can be configured together to detect light or other radiation reflected, refracted, conducted, or fluoresced by receptors 310. Data received from multiple fibers can be processed by a reception system 330 to allow for observation of different locations on a substrate. In the embodiment shown in FIG. 5, the substrate 340 is not coupled to the fibers. In an alternative embodiment, a substrate can be coupled to a distal end of a fiber, and receptors can be coupled to the substrate. In an embodiment, the present artificial receptors can be coupled directly to the fiber.
Various types of optical sensors can be provided, such as intensity-based sensors, interference-based sensors, polarization-based sensors, wavelength-based sensors, nonlinear optics-based sensors, and multiphoton-based sensors. Other detectors such as photomultiplier tubes, photo diodes, photodiode arrays, and microchannel plates can also be provided. Bundled fibers and fiber arrays can also be configured to detect a plurality of the present artificial sensors.
Fiber optic detection systems can operate based upon direct or indirect detection. Directly detectable labels provide a directly detectable signal without interaction with one or more additional chemical agents. Suitable directly detectable labels include colorimetric labels, fluorescent labels, and the like. Indirectly detectable labels interact with one or more additional agents to provide a detectable signal. Suitable indirect labels include a labeled antibody and the like.
A detection system can be configured to detect the intrinsic optical properties of a sample, such as the refractive index, the color, or the emission (e.g. fluorescence) or absorption (e.g. quench fluorescence) properties of a sample. In an embodiment, the presence of a test ligand bound to a receptor can be detected based upon variations in one or more properties that are associated with the presence of the test ligand. In an embodiment, the concentration of a test ligand or a label in a sensed region is a function of the concentration of the analyte that binds to a particular receptor, which can be determined from the optical properties or behavior of the sample. In an embodiment, a label can be bound to the analyte. In an embodiment, a label can be bound to a blocking analyte. Use of labels is further described in U.S. Pat. No. 5,690,894.
Fiber optic systems can allow flexibility in detection configurations. For example, a fiber optic system can be configured to allow detection in locations that can be otherwise difficult to access. Detection at a distance is also possible through use of one or more fibers. A group of fibers can be configured to collect an array or data, as further described below. Detection at multiple points along a fiber or a bundle of fibers is also possible.
A fiber optic detection system can be configured in a sensing or a probing configuration. A sensing configuration allows for a stream of data. For example, a sensing system can be configured to sense continuously. A probing configuration takes a sample of data (i.e. a “snapshot”) at a particular point in time. A fiber optic probe can be configured to take a single data samples, or multiple samples. In an embodiment, for example, a fiber optic probe can be configured to take periodic data samples.
In an embodiment, the present artificial receptors can be configured in conjunction with an optical imaging fiber. An optical imaging fiber can be formed from a multiplicity of individual fibers that are melted and drawn together in a coherent manner such that an image can be carried from one end of the fiber to the other. In an embodiment, an optical imaging fiber can be configured to detect the presence, condition or behavior of a ligand (e.g. a test ligand) that binds to the present artificial receptors. Such imaging fibers can also be configured in conjunction with chemically sensitive polymer matrices to combine imaging and chemical sensing. This allows for simultaneous optical detection and measurement of chemical dynamics occurring in a sample.
In an embodiment, the present artificial receptors can be configured for use in optical tweezers. An optical tweezer traps particles using focused laser beams to form optical traps. Optical tweezers are described in published U.S. Patent Application No. 20030032204.
While fiber optic waveguides have been described in many of the above applications, waveguides having other geometries (e.g. planar or strip) can also be configured for use with the receptors. Various mode structures (e.g. single-mode or multi-mode), refractive index distributions (step or gradient index) and material compositions (e.g. glass, polymer, semiconductor) can be employed. In an embodiment, receptors can be coupled to a surface of a planar wave guide. Signals can be captured and conveyed through a fiber where they can be analyzed by a computer system. A fluorometric-based sensor system that uses a planar waveguide is described in United States Published Patent Application No. 2002/0160535.

Optical Signals

A detectable optical signal can be produced by the interaction of a ligand with the present artificial receptor or through binding of a labeled moiety to the ligand. Fiber optic detection systems can be configured to detect a variety of optical signals, including those produced by physical, chemical, or biological. For example, the detection systems can be configured to detect one or more of refractive index, color, emission, absorption, fluorescence, or fluorescence quenching properties of a sample, and/or changes to those properties.
The presence of a test ligand binding to the present artificial receptor can affect the quality or quantity of optical signal that is detected through a fiber. The presence of two or more test ligands that are bound to the present artificial receptors (or to each other) can also generate detectable changes in an optical signal or property.
In an embodiment, a change in fluorescence or quenching of fluorescence can be detected. Fluorescence is the emission of radiation following the absorption of radiation of a different wavelength. For example, an embodiment of a fluorescing substance can emit visible light after being exposed to ultraviolet light. In an embodiment, the present artificial receptor can include a fluorescent molecule whose fluorescent properties (e.g., emission intensity, emission wavelength, or lifetime) change upon analyte binding. Sensors employing the present artificial receptors can be configured to detect fluorescent decay time.
Sensors employing the present artificial receptors can be configured to detect the quenching of fluorescence. The quenching of fluorescence can occur in a variety of forms. Dynamic quenching can occur where a collisional encounter between the quencher and the excited state is involved. The lifetime and intensity of the emission can be decreased by dynamic quenching. Concentration quenching can occur where a molecule quenches its own fluorescence at high concentration. ‘Static’ quenching can occur where an interaction between the fluorophore and quencher is involved. Color-quenching can occur where photons that are emitted are reabsorbed by a strongly colored component of the sample. Color quenching is often accompanied by another quenching process based on Fluorescent Resonance Energy Transfer (‘FRET’). This is a radiation-less process where excited species transfer excitation energy to a neighbor having an absorption that overlaps the fluorophore's emission spectrum.
Sensors configured with the present artificial receptors can also be configured to detect fluorescence polarization. Fluorescence polarization refers to the fact that fluorescent molecules in solution which are excited with plane-polarized light will emit light back into a fixed plane if the molecules remain stationary during the excitation of the fluorophore. If the molecule rotates during the excited state, light is emitted in a different plane. The intensity of light emitted can be monitored in a plane to monitor the rotation of fluorescing molecules. Large molecules tend to rotate slower than small molecules. Fluorescence polarization measurements can thus be used to study molecular interactions. For example, the bound/free ratio of fluorescing molecules can be detected. A sensor that detects the fluorescence polarization of a label is described in U.S. Pat. No. 6,555,326.
Sensors employing the present artificial receptors can be configured to detect evanescent wave properties. Evanescent wave-based sensors are described by U.S. Pat. Nos. 5,525,800, 5,639,668, and 6,731,827.
Sensors employing the present artificial receptors can be configured to detect phenomena such as chemiluminescence, bioluminescence, or chemibioluminescence. Chemiluminescence is the generation of electromagnetic radiation as light by the release of energy from a chemical reaction. Chemical reactions using synthetic compounds and usually involving a highly oxidized species such as a peroxide are commonly termed chemiluminescent reactions. Light-emitting reactions arising from a living organism, such as the firefly or jellyfish, are commonly termed bioluminescent reactions. Light-emitting reactions which take place by the use of electrical current are designated electrochemiluminescent reactions.
Sensors employing the present artificial receptors can be configured to use multi-parametric techniques. For example, multi-parametric fluorescence techniques can be performed based on based on spectral change, intensity, lifetime and polarization of radiation. In an embodiment, for example, refractive index, emission, and abortion properties can also be monitored concurrently. Other combinations are possible.
In an embodiment, a charge-coupled device (CCD) camera can be configured to detect optical signals from a system that incorporates the present artificial receptors. In an embodiment, a long-duration exposure can be used to gather data over a period of time. Filters can also be configured to separate signals by wavelength.
In an embodiment, a near field array can be created on optical fibers and configured to observe an object to which the present artificial receptor can be coupled.

Optical Sensor Arrays

In an embodiment, fiber optic sensors can be arranged to provide an array of data. For example, in an embodiment, present artificial receptors can be arranged on a surface in an array. The array of present artificial receptors can be detected by a single fiber, or by a group of fibers. In an embodiment, an array of present artificial receptors can be positioned at the end of a fiber. For example, the present artificial receptors can be coupled to the end of the fiber in an array pattern. Alternatively, present artificial receptors can be bonded, suspended, or otherwise positioned on an object, such as a glass plate, with a fiber operatively arranged to allow detection with respect to the plate.
In an embodiment, an array of fibers can be configured with the present artificial sensors to gather a data array. In an embodiment, an array of fibers can be positioned to provide data samples from a variety of positions. In an embodiment, a variety of present artificial receptors which can be arranged in a pattern allow for simultaneous monitoring for a plurality of test ligands. Other variations or combinations of these sensor techniques are possible. Optical fiber sensor arrays are further described in U.S. Pat. Nos. 5,690,894, 6,667,159, and 6,680,206.
In an embodiment, a plurality of fibers can be configured in a bundle 1100, as shown in FIG. 11. Particular receptors can be associated with particular fibers, or groups of fibers. For example, in an embodiment, particular receptors can be coupled to fibers at a first end 1110 of a bundle, and particular test ligands can be identified based upon signals received at a second end 1120 of the bundle.
Techniques for analyzing a sample array include time-resolved spectroscopy, spatially-resolved spectroscopy, evanescent wave spectroscopy, laser-assisted spectroscopy, surface plasmon spectroscopy, and multi-dimensional data acquisition. Fiber bundles can be configured to form a sensor array, which can be used for imaging or for data acquisition. In an embodiment, an artificial neural network can be configured to process data from a fiber bundle array. An artificial neural network deconvolutes a signal to allow association of data signal patterns with the presence of a particular test ligand or group of test ligands. For example, it may be determined that when a particular test ligand is present, a particular combination of signals can be detected through the fiber array. As data is collected, detection of a new test ligand or combination of test ligands can be determined.
In an embodiment, sensors based on fiber optic technology in combination with the present artificial receptors can be configured to continuously measure the concentration (or concentration changes) of various components of biological and environmental samples.

Electrochemical Sensors

The present artificial receptors can also be configured for use in electrochemical sensors. The present artificial receptors can be configured for example with a variety of electrochemical sensors, including chemically modified electrode sensors and microelectrodes. Sensing schemes include, for example, voltametric and potentiometric methods. Electrochemical sensors can be configured to detect any of a variety of test ligands.
In an embodiment, an electrochemical sensor includes the present artificial receptors coupled to or near an electrode. In an embodiment, if a test ligand binds to a receptor, the presence of the test ligand can be detected based on electrical monitoring. For example, the presence of a particular test ligand can create an electrical charge. The electrical charge can create a detectable current or voltage differential. In an embodiment, when a chemically reactive gas is either oxidized (accepts oxygen and/or gives up electrons) or reduced (gives up oxygen and/or accepts electrons), a potential difference can be created, which can cause a current to flow. Non-reducible anions can be detected based upon electrochemical interaction between the anions and the receptors or redox active moieties operatively coupled to the receptors.
In an embodiment, an electrochemical sensor includes a working electrode (or “sensing” electrode), a reference electrode, and the present artificial receptor. The working electrode is exposed to a test ligand, and the reference electrode is not exposed to the test ligand. When the test ligand is present at the working electrode, an electrochemical reaction can occur. Typically, either an oxidation or reduction occurs, depending on the type of test ligand, but other reactions are possible. An oxidation reaction results in the flow of electrons from the working electrode to the reference electrode through an external circuit. A reduction reaction results in flow of electrons from the reference electrode to the working electrode. This flow of electrons in the electric current is proportional to the test ligand concentration.
In an embodiment, present artificial receptors can be coupled to a working electrode. The receptors can be exposed to a sample suspected of containing a test ligand of interest. A chemical reaction can cause electrons to flow to or from the working electrode. For example, in an embodiment, the receptors can be exposed to the sample, and a test ligand in the sample can bind to the receptors. The receptors and bound test ligand from the sample can be exposed to a reactive substance such as an electrolyte, which can cause a chemical reaction, which in turn can cause a current to flow.
FIG. 6 shows an embodiment of an electrochemical sensor 400. The present working receptors 410 can be coupled to a working electrode 420. Working electrode 420 and a reference electrode 440 can be electrically coupled to an electrical sensing device 430, which can be configured to detect, for example, voltage or current. While receptors 410 are shown coupled directly to working electrode 420, the receptors can alternatively be coupled to a substrate that can be electrically coupled to the working electrode.
In an embodiment, an electrochemical sensor includes a membrane. The present artificial receptors can be attached or otherwise coupled to the membrane. FIG. 7 shows an embodiment of an electrochemical sensor 500 where the present working receptors 510 can be coupled to a membrane 520 between a working electrode 530 and a reference electrode 540, which can be coupled to an electrical sensing device 550. In an embodiment, the membrane is positioned between a working electrode and a test ligand.
In an embodiment, the present artificial receptors can be coupled to a conductive polymer film. For example, in an embodiment, the present artificial receptors can be coupled to a conductive polymer film which can be coupled to the surface of a platinum electrode or other electrode. In an embodiment, the present artificial receptors can be coupled to a conducting polypyrrole film.
In an embodiment, a thick-film electrode can be integrated in or on a glass substrate. In an embodiment, a thin-film Ag/AgCl electrode can be integrated on a glass substrate. Platinum electrodes can also be integrated in or on the glass substrate. A multi-electrode system can also be provided, with multiple electrodes being integrated in a single glass substrate.
The present artificial receptors can also be coupled to a semiconductor-based sensor. In an embodiment, a semiconductor-based sensor can be based on a electroadsorptive effect: An electrical field applied on a sensitive layer of a semiconductor alters the adsorption characteristics of the material.
The present artificial receptors can be configured with a field effect transistor, such as a MOSFET, CHEMFET, ISFET, SAFET, or SGFET. For example, the present artificial receptors can be coupled the FET device, or to an object in an environment in the viscinity of a FET device. In an embodiment, the present artificial receptors can be coupled to a layer of a metal-oxide-semiconductor (MOS) field effect transistor (FET), and the binding of a substance to an artificial receptor can be detected through the MOSTFET. Schematic illustrations of a ISFET, ChemFET, SAFET, and SGFET are provided in FIGS. 12A-12D respectively.
In an embodiment, the present artificial receptors can be configured with an ion selective field effect transistor (ISFET). A schematic illustration of an embodiment of an ISFET device 1200 is shown in FIG. 12A. In an embodiment, an ISFET operates based on effectsostatic effects caused by a test ligand binding to the present artificial receptors. In an embodiment, a chemically sensitive membrane 1205 or insulator layer can be configured to extend between a source 1210 and a drain 1215. In an embodiment, the present artificial receptors 1220 can be coupled to the chemically sensitive membrane or layer. Charges from chemicals that couple to the receptors and/or the membrane can be amplified through the operation of the FET signal the presence and/or identity of a chemical that is bound to the receptors.
In an embodiment, the present artificial receptors can be coupled to a chemically modified field effect transistor (ChemFET). A schematic illustration of a ChemFET 1225 is shown in FIG. 12B. In an embodiment, an oxide layer 1235 can extend between a drain 1245 and a source 1240, and a chemically sensitive gate 1250 can be layered on top of the oxide layer. In an embodiment, the present artificial receptors can be coupled to or embedded in the oxide layer 1235 or the gate layer 1250. In an embodiment, the layer or layers can be a gel or a membrane. In an embodiment, both a gel and a membrane can be layered on a gate surface.
In an embodiment, the present artificial receptors can be coupled to a surface accessible field effect transisitor (SAFET). FIG. 12C shows a schematic illustration of a SAFET device 1255 that includes a source 1275 and a drain 1280. In an embodiment, the present artificial receptors 1260 can be coupled to an insulator structure 1265 or a gate 1270.
In an embodiment, the present artificial receptors can be coupled to a suspended gate field effect transisitor (SGFET). FIG. 12D shows a schematic illustration of a SGFET 1285. In an embodiment, a chemically sensitive insulator structure 1290 can be layered on a drain 1295 and a source 1300, and a gate 1305 can be layered on the insulator structure 1290. A chemically sensitive mesh 1310 can be layered on the gate 1305. The present artificial receptors 1315 can be coupled to or embedded in one or more of the chemically sensitive mesh 1310, the gate 1305, and the insulator structure 1290.
In an embodiment, the present artificial receptors can be coupled to a carbon paste that is electrically coupled to an electrode. In an embodiment, electrochemical sensors that incorporate the present artificial receptors can be based on carbon paste screen-printed electrodes. In an embodiment, these sensors incorporate the conducting polymer polyaniline (PANI)/poly(vinylsulphonic acid) (PVSA). Such sensors can be useful in detecting and quantifying a redox active test ligand.
The present artificial receptors can also be configured with electrochemical impedance spectroscopy techniques. In an embodiment, the presence of a test ligand on a receptor can be detected through a variation in electrical properties at an electrode interface. For example, a shift in impedance, a change in capacitance, or a change in admittance (or resistance) can be detected.
In an embodiment, the present artificial receptors can be configured in reagentless sensors. For example, the present artificial receptors can be configured for use in reagentless amperometric immunosensors. In an embodiment, a present artificial receptor is fluorescent, and the fluorescent properties of the receptor change upon analyte binding. A reagentless assay kit is described in U.S. Pat. No. 6,660,532.
In an embodiment, optical and electrochemical sensors can be configured to simultaneously gather data regarding a sample. A thin film fiber optic sensor array and apparatus for concurrent viewing and chemical sensing of a sample is described in U.S. Pat. No. 5,298,741.
The present artificial receptor can also be configured with a multiple-element microelectrode array sensor. Such array sensors can be configured, for example, to detect a variety of different gasses or test ligands, or can monitor for a single test ligand at a variety of locations.
FIG. 8 shows an embodiment of a sensing system 600 where an array of electrochemical sensors 620 and an array of fiber optic sensors in a fiber cable 630 can be configured to detect signals from a multiplicity of present artificial receptors 610 that can be coupled to a substrate 640. A processing system 650 receives data from the array of electrochemical sensors and from the optical sensors. An example of a data pattern 800 received from an array of fibers is shown in FIG. 10. Locations 810 where a test ligand has bound to a present artificial receptor can be detected.

Sensor Applications

Sensors, sensor systems, and methods that employ the present artificial receptors can be configured to detect a variety of test ligands or measure a variety of properties or behaviors.

Artificial Sense of Smell or Taste

In an embodiment, a sensor system that mimics a human or mammal sense of smell or taste can be provided using the present artificial receptors. Such systems are sometimes referred to as an artificial tongue or artificial nose. In an embodiment, for example, a sample can be tested for bacteria, toxins, or poisons. In an embodiment, a system can be configured to detect, for example, a pathogenic microorganism, a cancerous cell, a pollutant in water, an airborne pollutant, an explosive-related vapor, protein, and/or a polynucleotide.
In an embodiment, the sample can be a food or beverage product. In an embodiment, an optical system can be configured to detect a change in optical properties of a sample, such as a change in the intrinsic fluorescence of the sample. Data obtained through a fiber or fiber bundle can be deconvoluted or otherwise processed. Complex mixtures of analytes can be identified and quantified. For example, in an embodiment, a data pattern obtained from a sample can be interpreted to identify and/or quantify the presence of a particular test ligand.
In an embodiment, the present artificial receptors can be configured in an artificial nose. For example, in an embodiment, the present artificial receptors can be configured to detect explosives vapor, for example to facilitate landmine detection. In an embodiment, an artificial nose includes a light source (or source of other electromagnetic radiation), an object to which the present artificial sensors can be coupled, and a CCD camera. In an embodiment, a vapor delivery system and a vapor removal system can also be provided. In an embodiment, vapors can be delivered to a sensing region of an artificial nose in pulses. To identify and quantify a test ligand in a sample, optical characteristics and behaviors such as change in fluorescence and/or shift in wavelength can be detected.
In an embodiment of an artificial nose, pattern recognition and/or neural network analysis can be configured to discriminate between explosives vapors and other organic vapors (e.g. background vapors.) In an embodiment, an array of optical sensors can be used. In an embodiment, the present artificial receptors can be coupled to a microbead that can be coupled to a microwell. In an embodiment, fluorescent signals can be processed and a signature can be mapped to allow identification, for example, of nitroamoratic compounds. In an embodiment, signals can be detected over a period of time and signal data can be processed to identify and/or quantify the test ligand(s) in a sample. In an embodiment, an artificial nose based on the present artificial receptors can be incorporated into a portable system that can be configured for use in the field, for example to detect land mines.

Microfluidic Systems

The present artificial receptors can be configured for use with microfluidic systems. A biosensor incorporating a microfluidic system is described in U.S. Pat. No. 6,716,620. Microfluidic systems are also described in U.S. Pat. Nos. 6,773,567; 6,756,019; 6,709,559; 6,670,153; 6,670,133; 6,635,487; 6,632,655; 6,534,013; 6,498,353; 6,488,895; and 6,465,257, and Published U.S. Patent Application Nos. 20040048360 and 20040028567. In an embodiment, an optical sensor can be utilized to detect the presence of a test ligand in a portion of a microfluidic system. In an embodiment, the present artificial receptors can be employed to extract a test ligand from a flow in a microfluidic system. Microfluidic systems can also be configured with indicator components using the present artificial receptors. Indicator components for microfluidic systems are described in Published U.S. Patent Application No. 20040141884.

Nanostructures

In an embodiment, the present artificial receptors can be configured for use in nanostructures. In an embodiment, the present artificial receptors can be configured for use in a colloidal assembly process. In an embodiment, the receptors are coupled to a larger particle. The colloidal assembly process can be performed such that smaller particles assemble around larger ones. In an embodiment, the larger particle can be etched away to produce a hollow sphere.
In an embodiment, the present artificial receptors can be coupled to cantilevers, which can for example be micron-scale arms. When a test ligand, a strand of DNA for example, bonds to the artificial receptors, a surface stress is induced which bends the cantilever. The bending of the cantilever arm can be detected, thereby allowing for detection of the presence of a test ligand bound to the present artificial receptor. In an embodiment, an array of cantilevers can be provided. In an embodiment, different test ligands can be detected (different genes for example) by coupling different artificial receptors to cantilevers or groups of canitilevers.
In an embodiment, the present artificial receptors can be configured with nanotubes. For example, the present artificial receptors can be coupled to a semiconducting carbon nanotube to facilitate detection of gasses.
In an embodiment, the present artificial receptors can be configured with semiconducting nanotubes that are configured to change electrical resistance when exposed to a particular test ligand, such as a gas. In an embodiment, the present artificial receptors are configured to block the binding of one or more test ligands with the a nanotube to allow detection of other substances by the nanotube.
In an embodiment, the present artificial receptors can be coupled to the surface of a semiconductor nanowire. For example the present artificial receptors can be coupled to a nanowire field effect transistor. In an embodiment, the nanowire field effect transistor can be coupled to or integrated into a silicon chip.

Sensor Coupled Communications Systems

Embodiments of the present artificial receptors can be configured with a sensor that is operatively coupled to a communication system. For example, a sensor employing the present artificial receptors can be coupled to a communications network using wired or wireless technology. The communications can, for example, be the Internet. A processing system that is also coupled to the communications network can monitor one or more signals from one or more sensors. In an embodiment of a responsive system, corrective action can be taken as necessary in response to signals received from a sensor.
Various types of sensors can be configured with a network. For example, electrochemical and fiber optic sensors can be configured with a network. In an embodiment, electrochemical, potentiometric, voltametric, and/or amperometric sensors that incorporate the present artificial receptors can be coupled to a data network. Absorbance and/or fluorescence-based sensors that incorporate the present artificial receptors can also be coupled to a data network. Other types of sensors that can include the present artificial receptors can also be coupled to a network. Systems can also be configured to gather and transmit data from a variety of sensors or sensor arrays.
In an embodiment, a sensor system can be coupled to a digital system that receives signals from the sensor system. In an embodiment, the digital system can also be configured to make adjustments to an environment. For example, an actuator can be activated to make an adjustment. In an embodiment, an item for which particular properties are detected can be removed from a product flow. For example a contaminated food product can be removed from an assembly line. In an embodiment, a system can be configured to detect a particular test ligand in a mail package, and the package can be isolated for processing or further analysis. In an embodiment, items such as aircraft luggage can be monitored for explosive vapors and responsive action can be initiated as necessary. Other embodiments are possible.

Methods Employing the Artificial Receptors

Working artificial receptors can be generated to be specific to a given test ligand or specific to a particular part of a given test ligand. Heterogeneous and immobilized combinations of building block molecules form the working artificial receptors. For example, combinations of 2, 3, 4, or 5 distinct building block molecules immobilized in proximity to one another on a support provide molecular structures that serve as candidate and working artificial receptors. The building blocks can be naïve to the test ligand. Once a plurality of candidate artificial receptors are generated, they can be tested to determine which are specific or useful for a given ligand.
The specific or working artificial receptor or receptor complex can then be used in a variety of different methods and systems. For example, the receptors can be employed in methods and/or devices for binding or detecting a test ligand. By way of further example, the receptors can be employed in methods and/or devices for chemical synthesis. Methods and systems for chemical synthesis can include methods and systems for regiospecific and stereospecific chemical synthesis. The receptors can also be employed for developing compounds that disrupt or model binding interactions. Methods and systems for developing therapeutic agents can include methods and systems for pharmaceutical and vaccine development.
In an embodiment, methods and systems of the present invention can be employed for detecting a plurality of ligands of interest. For example, an unknown biological sample can be characterized by the presence of a combination of specific ligands. Such a method can be useful in assays for detecting specific pathogens or disease states. By way of further example, such an embodiment can be used for determining the genetic profile of a subject. For example, cancerous tissue can be detected or a genetic disposition to cancer can be detected.
The present artificial receptors can be part of products used in: analyzing a genome and/or proteome (protein isolation and characterization); pharmaceutical development (such as identification of sequence specific small molecule leads, characterization of protein to protein interactions); detectors for a test ligand; drug of abuse diagnostics or therapy (such as clinical or field analysis of cocaine or other drugs of abuse); hazardous waste analysis or remediation; chemical exposure alert or intervention; disease diagnostics or therapy; cancer diagnostics or therapy (such as clinical analysis of prostate specific antigen); biological agent alert or intervention; food chain contamination analysis or remediation and clinical analysis of food contaminants; and the like.

Methods of Binding or Detecting Test Ligands

In an embodiment, the invention can include methods and/or devices for binding or detecting a test ligand. For example, the present artificial receptors can be used for a variety of assays that presently employ an antibody. The present artificial receptors can be specific for a given ligand, such as an antigen or an immunogen. Thus, the present artificial receptors can be used in formats analogous to enzyme immunoassay, enzyme-linked immunoassay, immunodiffusion, immunoelectrophoresis, latex agglutination, and the like. Test ligands that can be detected in such a method include a drug of abuse, a biological agent (such as a hazardous agent), a marker for a biological agent, a marker for a disease state, etc. Methods and systems for detection can include methods and systems for clinical chemistry, environmental analysis, and diagnostic assays of all types.
For example, the artificial receptor can be contacted with a sample including or suspected of including at least one test ligand. The building blocks making up the artificial receptors can be naïve to the test ligand. Then, binding of one or more of the test ligands to the artificial receptors can be detected. Next, the binding results can be interpreted to provide information about the sample. In an embodiment, the invention includes a method for detecting a test ligand in a sample including contacting an artificial receptor specific to the test ligand with a sample suspected of containing the test ligand. The method can also include detecting or quantitating binding of the test ligand to the artificial receptor. For example, an artificial receptor that binds (e.g., tightly) the molecule, cell, or microbe under appropriate conditions can be employed in a format where binding itself is sufficient to indicate presence of the molecule or organism. Such a format can also include artificial receptors to be probed with positive and control samples.
FIG. 14 schematically illustrates an embodiment of a method for evaluating candidate artificial receptors for binding to a test ligand, such as a molecule or cell. The method can include making an array of candidate artificial receptors. Working artificial receptors can be identified by contacting the array with test ligand and identifying which receptors bind the test ligand. The building blocks making up the artificial receptors can be naïve to the test ligand. Such a method can employ a labeled test ligand. The method can include producing an array or device including the working artificial receptor or receptor complex. In an embodiment, the method can include employing the array or device for detecting or characterizing the test ligand in a sample, such as a biological, laboratory, or environmental sample.
FIG. 15 schematically illustrates an embodiment of the present method employing an array of candidate artificial receptors. This embodiment of the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a test ligand. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to a test ligand, e.g., a molecule or cell. The building blocks making up the artificial receptors can be naïve to the test ligand. The molecule or cell can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting the molecule or cell.
As illustrated in FIG. 15, a test ligand can be identified by a method employing a single or a plurality of lead or working artificial receptors. The plurality of lead or working artificial receptors suitable for identifying a test ligand can be employed in an array format test. A single lead or working artificial receptor can be configured on a support as a strip together with positive and/or negative control receptors, which can also be configured as strips.
In an embodiment, the method can include producing or employing the selected working artificial receptor or receptor complex on a substrate. The substrate can include working artificial receptors for a single test ligand or working artificial receptors for a plurality of test ligands. For example, a method can include contacting the artificial receptors with a sample. A substrate including working artificial receptors for a single test ligand can be employed in a method or system for detecting that test ligand. Binding to the working artificial receptors indicates that the sample includes the test ligand. A substrate including working artificial receptors for a plurality of test ligands can be employed in a method or system for detecting one, several, or all of the test ligands. Binding to the working artificial receptors for a particular test ligand or ligands indicates that the sample includes such test ligand or ligands.
The working artificial receptors or receptor complexes can be configured to provide a pattern indicative of the presence of one or more of the test ligands. The method can include detecting the binding pattern of the sample and comparing it with binding patterns from known samples. FIG. 16 schematically illustrates certain binding patterns on an array of working artificial receptors. In an embodiment, all artificial receptors for one test ligand can be arranged in a line across the substrate. Referring to FIG. 16, receptors that are specific for IL-2 are in a line 12 on the array 10 of working artificial receptor complexes. Working artificial receptors that have bound a test ligand (e.g., IL-2) are indicated as shaded 24. Working artificial receptors that have not bound a test ligand are illustrated as open circles 26.
A method employing the illustrated array can include detecting binding on line 12 of working artificial receptors through fluorescence or another means described herein. In the illustrated embodiment, detecting binding on line 12 of working artificial receptors indicates that the sample contains IL-2. Further, lack of signal from the other working artificial receptors in array 10 indicates that the sample does not contain IFN-gamma, IL-10, TGF-beta, IL-12, or TGF-alpha. Thus, a method employing such an array can determine whether a sample is a particular type of biological sample or contains a particular type of molecule or cell.
When designed for use with a field assay kit, the device 30 can have spots arranged such that a positive result creates an easily recognizable pattern 36, such as a plus sign. The readily recognizable pattern can thus indicate that a particular test ligand is present in the sample. Alternatively, the artificial receptors or spots for a particular target 42 can be arranged randomly on third array 40. In this manner, when the detection device or array is used, the results of the test may not be immediately apparent to an observer but will be readily read by a machine which can be programmed to correlate binding to receptors or spots in different positions with the identity of a particular biological sample, molecule, or cell.
In an embodiment, the invention includes a method for detecting or characterizing a biological sample, a molecule, or cell. This embodiment of the method can include selecting an artificial receptor that binds the biological sample, molecule, or cell from an array of artificial receptors, contacting the artificial receptor with a test composition, and detecting binding of the artificial receptor to the test composition. In such an embodiment, binding indicates the presence of the biological sample, molecule, or cell in the test composition. In an embodiment, the invention includes a method for detecting or characterizing a biological sample, molecule, or cell. This embodiment of the method can include contacting an array of artificial receptors with a test composition and detecting binding to the artificial receptors. Binding indicates the presence of the biological sample, molecule, or cell in the test composition.
The present method can develop or employ a plurality of working receptors specific for a particular test ligand, e.g., biological sample, molecule, or cell. That is, the working receptors can be specific for a particular test ligand, but different receptors can interact with different distinct antigens (e.g., proteins or carbohydrates), ligands, functional groups, or structural features of the test ligand. Such a method can provide a robust test for the presence of a test ligand. For example, such a robust test can reduce the chances of a false-positive or false-negative result in comparison with an assay that relies upon a single unique receptor to detect a given test ligand. Further, this embodiment of the method can develop or employ working receptors that demonstrate higher binding affinity due to interaction with multiple antigens or ligands on the same test ligand (e.g., multivalent binding).
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a polynucleotide, e.g., DNA or RNA. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the polynucleotide, e.g., DNA or RNA. The building blocks making up the artificial receptors can be naïve to the DNA or RNA. The polynucleotide, e.g., DNA or RNA, can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting the polynucleotide, e.g., DNA or RNA.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a polypeptide or peptide. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the polypeptide or peptide. The building blocks making up the artificial receptors can be naïve to the polypeptide or peptide. The polypeptide or peptide can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting the polypeptide or peptide.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a oligo- or polysaccharide. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the oligo- or polysaccharide. The building blocks making up the artificial receptors can be naïve to the oligo- or polysaccharide. The oligo- or polysaccharide can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting the oligo- or polysaccharide.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a cell, e.g., a hepatocyte. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the cell, e.g., a hepatocyte. The building blocks making up the artificial receptors can be naïve to the cell. The cell, e.g., a hepatocyte, can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting the cell, e.g., a hepatocyte.

Methods of Binding or Detecting Drugs of Abuse

In an embodiment, the invention can include methods and/or devices for binding or detecting a drug of abuse. Methods and systems for detection can include methods and systems for clinical chemistry, field analysis, and diagnostic assays of all types. For example, the artificial receptor can be contacted with a sample including or suspected of including at least one drug of abuse. Then, binding of one or more of the drugs of abuse to the artificial receptors can be detected. Next, the binding results can be interpreted to provide information about the sample. In an embodiment, the invention includes a method for detecting a drug of abuse in a sample including contacting an artificial receptor specific to the drug of abuse with a sample suspected of containing the drug of abuse. The method can also include detecting or quantitating binding of the drug of abuse to the artificial receptor.
FIG. 14 schematically illustrates an embodiment of a method for evaluating candidate artificial receptors for binding to a test ligand. This embodiment of the present method can be employed for detecting a test ligand such as a drug of abuse. The method can include making an array of candidate artificial receptors. The building blocks making up the artificial receptors can be naïve to the test ligand. Working artificial receptors can be identified by contacting the array with a drug of abuse and identifying which receptors bind the drug of abuse. The method can include producing an array or device including the working artificial receptor or receptor complex. In an embodiment, the method can include employing the array or device for detecting or characterizing the drug of abuse in a sample, such as a biological, laboratory, or evidence sample.
FIG. 15 schematically illustrates an embodiment of the present method employing an array of candidate artificial receptors. This embodiment of the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a drug of abuse. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to a drug of abuse. The building blocks making up the artificial receptors can be naïve to the drug of abuse. The drug of abuse can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological or field sample, or characterizing or detecting the drug of abuse.
In an embodiment, the method can include producing or employing the selected working artificial receptor or receptor complex on a substrate. The substrate can include working artificial receptors for a single drug of abuse or working artificial receptors for a plurality of drugs of abuse. For example, a method can include contacting the artificial receptors with a sample. A substrate including working artificial receptors for a single drug of abuse can be employed in a method or system for detecting that drug of abuse. Binding to the working artificial receptors indicates that the sample includes the drug of abuse. A substrate including working artificial receptors for a plurality of drugs of abuse can be employed in a method or system for detecting one, several, or all of the drugs of abuse. Binding to the working artificial receptors for a particular drug of abuse or drugs of abuse indicates that the sample includes such a drug of abuse or drugs of abuse.
The working artificial receptors or receptor complexes can be configured to provide a pattern indicative of the presence of one or more of the drugs of abuse. The method can include detecting the binding pattern of the sample and comparing it with binding patterns from known samples. FIG. 16 schematically illustrates binding patterns on an array of working artificial receptors. Such patterns and schemes can be employed for identifying a variety of test ligands including drugs of abuse.
The present method can develop or employ a plurality of working receptors specific for a particular drug of abuse or feature on the drug of abuse. That is, the working receptors can be specific for a particular drug of abuse, but different receptors can interact with different distinct ligands, functional groups, or structural features of the drug of abuse. Such a method can provide a robust test for the presence of a drug of abuse. For example, such a robust test can reduce the chances of a false-positive or false-negative result in comparison with an assay that relies upon a single unique receptor to detect a given drug of abuse. Further, this embodiment of the method can develop or employ working receptors that demonstrate higher binding affinity due to interaction with multiple ligands or features on the same drug of abuse (e.g., multivalent binding).
Suitable drugs of abuse include cannabinoids (e.g., hashish and marijuana), depressants (e.g., barbiturates, benzodiazepines, gamma-hydroxy butyrate, methaqualone), dissociative anesthetics (e.g., ketamine, PCP, and PCP analogs), hallucinogens (e.g., LSD, mescaline, psilocybin), opiates or opioids (e.g., codeine, fentanyl, fentanyl analogs, heroin, morphine, opium, oxycodone HCL, hydrocodone bitartrate), stimulants (e.g., amphetamine, cocaine, methylenedioxy-methamphetamine, methamphetamine, methylphenidate, nicotine), inhalants (e.g., solvents), and the like.
Suitable drugs of abuse include performance enhancing agents, such as stimulants and beta-blockers, anabolic agents, oxygen carrier enhancers, masking agents, and inhalants. Suitable stimulants include caffeine and amphetamines. Suitable beta-blockers include salbutamol (used in asthma inhalers) and the like. Suitable anabolic agents include steroids (e.g., anabolic steroids), steroid analogs, and growth hormone. Suitable oxygen carrier enhancers include erythropoietin and the like.

Methods of Binding or Detecting Isomers

In an embodiment, the invention can include methods and/or devices for binding or detecting an isomer or isomers of a compound. Methods and systems for detection can include methods and systems for clinical chemistry, environmental analysis, and diagnostic assays of all types. For example, the artificial receptor can be contacted with a sample including or suspected of including at least one isomer of a compound. Then, binding of one or more of the isomers of a compound to the artificial receptors can be detected. Next, the binding results can be interpreted to provide information about the isomers. In an embodiment, the invention includes a method for detecting an isomer of a compound in a sample including contacting an artificial receptor specific to the isomer with a sample suspected of containing the isomer. The method can also include detecting or quantitating binding of the isomer to the artificial receptor.
The present method can be applied to isomers such as stereoisomers (e.g., geometric isomers or optical isomers), optical isomers (e.g., enantiomers and diastereomers), geometric isomers (e.g., cis- and trans-isomers). The present method can be employed to develop working or lead artificial receptors or working artificial complexes that can bind to one or more isomers of a compound (e.g., enantioselective receptor environments). For example, the artificial receptor or complex can bind to one stereoisomer of a compound but bind only weakly or not at all another stereoisomer of the compound. For example, the artificial receptor or complex can bind one geometric isomer of a compound but bind only weakly or not at all another geometric isomer. For example, the artificial receptor or complex can bind one optical isomer of a compound but bind only weakly or not at all another optical isomer. For example, the artificial receptor or complex can bind one enantiomer of a compound but bind only weakly or not at all another enantiomer. For example, the artificial receptor or complex can bind one diastereomer of a compound but bind only weakly or not at all another diastereomer.
FIG. 14 schematically illustrates an embodiment of a method for evaluating candidate artificial receptors for binding to a test ligand. This embodiment of the present method can be employed for detecting a test ligand such as an isomer of a compound. The method can include making an array of candidate artificial receptors. The building blocks making up the artificial receptors can be naïve to the test ligand. Working artificial receptors can be identified by contacting the array with an isomer and identifying which receptors bind the isomer. The method can include producing an array or device including the working artificial receptor or receptor complex. In an embodiment, the method can include employing the array or device for detecting or characterizing the isomer in a sample, such as a biological, laboratory, or clinical sample.
FIG. 15 schematically illustrates an embodiment of the present method employing an array of candidate artificial receptors. This embodiment of the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting an isomer. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to an isomer. The building blocks making up the artificial receptors can be naïve to the isomer. The isomer can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological, clinical, or laboratory sample, or characterizing or detecting the isomer.
In an embodiment, the method can include producing or employing the selected working artificial receptor or receptor complex on a substrate. The substrate can include working artificial receptors for a single isomer or working artificial receptors for a plurality of isomers. For example, a method can include contacting the artificial receptors with a sample. A substrate including working artificial receptors for a single isomer can be employed in a method or system for detecting that isomer. Binding to the working artificial receptors indicates that the sample includes the isomer. A substrate including working artificial receptors for a plurality of isomers can be employed in a method or system for detecting one, several, or all of the isomers. Binding to the working artificial receptors for a particular isomer or isomers indicates that the sample includes such an isomer or isomers.
The working artificial receptors or receptor complexes can be configured to provide a pattern indicative of the presence of one or more of the isomers. The method can include detecting the binding pattern of the sample and comparing it with binding patterns from known samples. FIG. 16 schematically illustrates binding patterns on an array of working artificial receptors. Such patterns and schemes can be employed for identifying a variety of test ligands including isomers.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a stereoisomer. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the stereoisomer. The building blocks making up the artificial receptors can be naïve to the stereoisomer. The stereoisomer can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a lab or clinical sample or characterizing or detecting the stereoisomer.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a geometric isomer (e.g., cis- and trans-isomers). The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the geometric isomer (e.g., cis- and trans-isomers). The building blocks making up the artificial receptors can be naïve to the geometric isomer. The geometric isomer can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a lab or clinical sample or characterizing or detecting the geometric isomer (e.g., cis- and trans-isomers).
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting an optical isomer. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the optical isomer. The building blocks making up the artificial receptors can be naïve to the optical isomer. The optical isomer can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a lab or clinical sample or characterizing or detecting the optical isomer.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting an enantiomer. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the enantiomer. The enantiomer can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a lab or clinical sample or characterizing or detecting the enantiomer.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a diastereomer. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the diastereomer. The building blocks making up the artificial receptors can be naïve to the diastereomer. The diastereomer can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a lab or clinical sample or characterizing or detecting the diastereomer.

Methods for Binding or Detecting Peptides

In an embodiment, the invention can include methods and/or devices for binding or detecting a peptide. Methods and systems for detection can include methods and systems for clinical chemistry, environmental analysis, and diagnostic assays of all types. For example, the artificial receptor can be contacted with a sample including or suspected of including at least one peptide. Then, binding of one or more of the peptides to the artificial receptors can be detected. Next, the binding results can be interpreted to provide information about the sample. In an embodiment, the invention includes a method for detecting a peptide in a sample including contacting an artificial receptor specific to the peptide with a sample suspected of containing the peptide. The method can also include detecting or quantitating binding of the peptide to the artificial receptor.
FIG. 14 schematically illustrates an embodiment of a method for evaluating candidate artificial receptors for binding to a test ligand. This embodiment of the present method can be employed for detecting a test ligand such as a peptide. The method can include making an array of candidate artificial receptors. The building blocks making up the artificial receptors can be naïve to the test ligand. Working artificial receptors can be identified by contacting the array with a peptide and identifying which receptors bind the peptide. The method can include producing an array or device including the working artificial receptor or receptor complex. In an embodiment, the method can include employing the array or device for detecting or characterizing the peptide in a sample, such as a biological, laboratory, or clinical sample.
FIG. 15 schematically illustrates an embodiment of the present method employing an array of candidate artificial receptors. This embodiment of the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a peptide. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to a peptide. The building blocks making up the artificial receptors can be naïve to the peptide. The peptide can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological or environmental sample, or characterizing or detecting the peptide.
FIG. 17 schematically illustrates an embodiment of a method for developing a method and system for detecting a test ligand, such as a peptide or mixture of peptides. This embodiment of the present method includes evaluating a plurality (e.g. array) of candidate artificial receptors for binding to each of a plurality of peptides. The building blocks making up the artificial receptors can be naïve to one or more of the peptides. The plurality of peptides can include the peptides found in a cell or organism. The method can include detecting binding of individual peptides to a subset of the plurality or array of candidate artificial receptors. The method can include detecting binding of the peptides found in a cell or organism to a subset of or all of the plurality or array of candidate artificial receptors. This can be envisioned as developing a working artificial receptor or artificial receptor complex for each peptide or mixture of peptides.
Thus, each peptide or mixture of peptides can provide a pattern of bound receptors in the plurality or array. The pattern of bound receptors can be characteristic of the peptide or mixture of peptides or a sample including the peptide or mixture of peptides. The method can include storing a representation of the binding pattern as an image or a data structure. The representation of the binding pattern can be evaluated either by an operator or data processing system. The method can include such evaluating. A binding pattern from an unknown sample that matches the binding pattern for a particular peptide then characterizes the unknown sample as containing that peptide. A binding pattern from an unknown sample that matches the binding pattern for a particular mixture of peptides then characterizes the unknown sample as including or being that mixture of peptides or as including or being the organism or cell containing that mixture of peptides. A plurality of binding patterns can be stored as a database.
An embodiment of the illustrated method can include creating an array of artificial receptors. This embodiment can also include compiling a database of the binding patterns of a specific peptide or mixture of peptides, for example, by probing the array with a plurality of individual peptides or the peptides found in a cell or organism. Contacting the array with an unidentified peptide or mixture of peptides can create a test binding pattern. The method can then compare the test binding pattern with the binding patterns of known peptides or mixtures of peptides in the database in order to characterize or classify the unidentified peptide, mixture of peptides, or cell or organism. In an embodiment, the database and the array of receptors has already been constructed and the method involves probing the array with an unknown peptide or mixture of peptides to create a test binding pattern and then comparing this binding pattern with the binding patterns in the database in order to characterize or classify the unidentified peptide, mixture of peptides, or cell or organism.
An array constructed for distinguishing mixtures of peptides can be contacted with samples from an organism, cell, or tissue of interest. Peptides that bind to the array can characterize or detect the organism, cell or tissue; can indicate a disorder caused by the organism or affecting the cell or tissue; can indicate successful therapy of a disorder caused by the organism or affecting the cell or tissue; characterize disease processes; identify therapeutic leads or strategies; or the like.
In an embodiment, the method can include producing or employing the selected working artificial receptor or receptor complex on a substrate. The substrate can include working artificial receptors for a single peptide or working artificial receptors for a plurality of peptides. For example, a method can include contacting the artificial receptors with a sample. A substrate including working artificial receptors for a single peptide can be employed in a method or system for detecting that peptide. Binding to the working artificial receptors indicates that the sample includes the peptide. A substrate including working artificial receptors for a plurality of peptides can be employed in a method or system for detecting one, several, or all of the peptides. Binding to the working artificial receptors for a particular peptide or peptides indicates that the sample includes such a peptide or peptides.
The working artificial receptors or receptor complexes can be configured to provide a pattern indicative of the presence of one or more of the peptides. The method can include detecting the binding pattern of the sample and comparing it with binding patterns from known samples. FIG. 16 schematically illustrates binding patterns on an array of working artificial receptors. Such patterns and schemes can be employed for identifying a variety of test ligands including peptides.
The present method can develop or employ a plurality of working receptors specific for a particular peptide or feature on the peptide. That is, the working receptors can be specific for a particular peptide, but different receptors can interact with different distinct ligands, functional groups, or structural features of the peptide. Such a method can provide a robust test for the presence of a peptide. For example, such a robust test can reduce the chances of a false-positive or false-negative result in comparison with an assay that relies upon a single unique receptor to detect a given peptide. Further, this embodiment of the method can develop or employ working receptors that demonstrate higher binding affinity due to interaction with multiple ligands or features on the same peptide (e.g., multivalent binding).
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a peptide. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the peptide. The building blocks making up the artificial receptors can be naïve to the test ligand. The peptide can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or characterizing or detecting the peptide.
The present method can include selecting artificial receptors that bind a particular peptide and/or the building blocks making up these receptors (e.g., bound to a scaffold molecule) as leads for pharmaceutical development or as active agents for modulating an activity of that peptide. The artificial receptor or building blocks making up that artificial receptor can be selected to bind to a portion of a peptide required for its interaction with an other macromolecule (e.g. carbohydrate, protein, or polynucleotide), thus disrupting this interaction.

Methods for Binding or Detecting Protein or Proteome

In an embodiment, the invention can include methods and/or devices for binding or detecting a protein, one or more of a plurality of proteins, or a proteome. Methods and systems for detection can include methods and systems for clinical chemistry, environmental analysis, diagnostic assays, and for proteome analysis. For example, the artificial receptor can be contacted with a sample including at least one protein or one proteome. The building blocks making up the artificial receptors can be naïve to the test ligand. Then, binding of one or more proteins to the artificial receptors can be detected. Next, the binding results can be interpreted to provide information about the sample, e.g., the proteome. In an embodiment, the invention includes a method for detecting a protein in a sample including contacting an artificial receptor specific to the protein with a sample suspected of containing the protein. The method can also include detecting or quantitating binding of the protein to the artificial receptor.
FIG. 14 schematically illustrates an embodiment of a method for evaluating candidate artificial receptors for binding to a test ligand. This embodiment of the present method can be employed for detecting a test ligand such as one or more proteins. The method can include making an array of candidate artificial receptors. The building blocks making up the artificial receptors can be naïve to the test ligand. Working artificial receptors can be identified by contacting the array with a protein and identifying which receptors bind the protein. The method can include producing an array or device including the working artificial receptor or receptor complex. In an embodiment, the method can include employing the array or device for detecting or characterizing the protein in a sample, such as a biological, laboratory, or environmental sample.
In an embodiment, the method can include producing or employing the selected working artificial receptor or receptor complex on a substrate. The substrate can include working artificial receptors for a single protein or working artificial receptors for a plurality of proteins. For example, a method can include contacting the artificial receptors with a sample. A substrate including working artificial receptors for a single protein can be employed in a method or system for detecting that protein. Binding to the working artificial receptors indicates that the sample includes the protein. A substrate including working artificial receptors for a plurality of proteins can be employed in a method or system for detecting one, several, or all of the proteins. Binding to the working artificial receptors for a particular protein or protein indicates that the sample includes such a protein or protein.
The working artificial receptors or receptor complexes can be configured to provide a pattern indicative of the presence of one or more of the proteins. The method can include detecting the binding pattern of the sample and comparing it with binding patterns from known samples. FIG. 16 schematically illustrates binding patterns on an array of working artificial receptors. Such patterns and schemes can be employed for identifying a variety of test ligands including proteins.
FIG. 17 schematically illustrates an embodiment of a method for developing a method and system for detecting a test ligand, such as a protein or proteome. This embodiment of the present method includes evaluating a plurality (e.g. array) of candidate artificial receptors for binding to each of a plurality of test ligands. The building blocks making up the artificial receptors can be naïve to the test ligand. The plurality of test ligands can include a plurality of proteins. The plurality of test ligands can include the proteins making up the proteome of a cell or organism. The method can include detecting binding of individual proteins to a subset of the plurality or array of candidate artificial receptors. The method can include detecting binding of proteins making up the proteome to a subset of or all of the plurality or array of candidate artificial receptors. This can be envisioned as developing a working artificial receptor or artificial receptor complex for each protein or for the proteome.
Thus, each protein or proteome can provide a pattern of bound receptors in the plurality or array. The pattern of bound receptors can be characteristic of the protein or proteome or a sample including the protein or proteome. The method can include storing a representation of the binding pattern as an image or a data structure. The representation of the binding pattern can be evaluated either by an operator or data processing system. The method can include such evaluating. A binding pattern from an unknown sample that matches the binding pattern for a particular protein then characterizes the unknown sample as containing that protein. A binding pattern from an unknown sample that matches the binding pattern for a particular proteome then characterizes the unknown sample as including or being that proteome or as including or being the organism or cell having that proteome. Similarly, a binding pattern from an unknown sample can be evaluated against the patterns of a plurality of particular proteins or proteomes and the sample can be characterized as containing one or more of the proteins or proteomes. A plurality of binding patterns can be stored as a database.
An embodiment of the illustrated method can include creating an array of artificial receptors. This embodiment can also include compiling a database of the binding patterns of specific proteins or proteomes, for example, by probing the array with a plurality of individual proteins or proteomes. Contacting the array with unidentified proteins or proteomes can create a test binding pattern. The method can then compare the test binding pattern with the binding patterns of known proteins or proteomes in the database in order to characterize or classify the unidentified protein, proteome, or cell or organism. In an embodiment, the database and the array of receptors has already been constructed and the method involves probing the array with an unknown protein or proteome to create a test binding pattern and then comparing this binding pattern with the binding patterns in the database in order to characterize or classify the unidentified protein, proteome, or cell or organism.
A proteome array can be contacted with samples from an organism, cell, or tissue of interest. Proteins that bind to the proteome array can characterize or detect the organism, cell or tissue; can indicate a disorder caused by the organism or affecting the cell or tissue; can indicate successful therapy of a disorder caused by the organism or affecting the cell or tissue; characterize disease processes; identify therapeutic leads or strategies; or the like.
The present method can develop or employ a plurality of working receptors specific for a particular protein or feature on the protein. That is, the working receptors can be specific for a particular protein, but different receptors can interact with different distinct ligands, functional groups, or structural features of the protein. Such a method can provide a robust test for the presence of a protein. For example, such a robust test can reduce the chances of a false-positive or false-negative result in comparison with an assay that relies upon a single unique receptor to detect a given protein. Further, this embodiment of the method can develop or employ working receptors that demonstrate higher binding affinity due to interaction with multiple ligands or features on the same protein (e.g., multivalent binding).
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a protein. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the protein. The building blocks making up the artificial receptors can be naïve to the test ligand. The protein can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or characterizing or detecting the protein.
The present method can include selecting artificial receptors that bind a particular protein and/or the building blocks making up these receptors (e.g., bound to a scaffold molecule) as leads for pharmaceutical development or as active agents for modulating an activity of that protein. The artificial receptor or building blocks making up that artificial receptor can be selected to bind to or disrupt the activity of the active site of an enzyme or the ligand binding site of a receptor. The artificial receptor or building blocks making up that artificial receptor can be selected to bind to a portion of a protein required for its interaction with an other macromolecule (e.g. carbohydrate, protein, or polynucleotide), thus disrupting this interaction. The artificial receptor or building blocks making up that artificial receptor can be selected to bind to the binding site of a receptor and act as an agonist of that receptor.
The present method can include selecting working artificial receptors that bind a preselected protein for use in a system for proteome analysis. The working artificial receptors for the preselected protein can be provided on a substrate and the protein bound to the receptors. In an embodiment, selecting and binding employ a plurality of different working artificial receptors for the preselected protein. The plurality of artificial receptors may bind to different features on the preselected protein and leave free different features on the preselected protein. This embodiment of the method includes contacting the working receptors with bound preselected protein to at least one candidate binding partner for the preselected protein. The method can include detecting binding or absence of binding of the candidate binding partner to the preselected protein. A candidate binding partner that binds to the preselected protein can be considered a lead binding partner.
In an embodiment, the method includes contacting the working receptors with bound preselected protein with a proteome of a cell or organism serving as the source of candidate binding partners. The method can then recover from the proteome one or more lead binding partners. This can then characterize the proteome as containing or not a binding partner for the preselected protein.
In an embodiment, the present artificial receptors can be employed in studies of proteomics. In such an embodiment, an array of candidate or working artificial receptors can be contacted with a mixture of peptides, polypeptides, and/or proteins. Each mixture can produce a characteristic fingerprint of binding to the array. In addition, identification of a specific receptor environment for a target peptide, polypeptide, and/or protein can be utilized for isolation and analysis of the target. That is, in yet another embodiment, a particular receptor surface can be employed for affinity purification methods, e.g. affinity chromatography.
In an embodiment, the present candidate artificial receptors can be employed to find receptor surfaces that bind proteins in a preferred configuration or orientation. Many proteins (e.g. antibodies, enzymes, receptors) are stable and/or active in specific environments. Defined receptor surfaces can be used to produce binding environments that selectively retain or orient the protein for maximum stability and/or activity. In an embodiment, the present artificial receptors can be employed to form bioactive surfaces. For example, receptor surfaces can be used to specifically bind the active conformation of an antibody or enzyme.
In an embodiment, the present method can include labeling a protein while it remains bound to an artificial receptor. The resulting protein will be labeled on its portions accessible to the labeling reagent but not on those portions bound to the artificial receptor. The method can include releasing the labeled protein from the artificial receptor. Determining the distribution of labels on the protein indicates which portion of the protein was bound to the receptor.
In certain embodiments, the present artificial receptors can be employed to distinguish between two conformations of a single protein. Certain proteins exist in two or more stable conformations. In an embodiment, the present working artificial receptor or complex can bind a first conformation of a protein. In an embodiment, the present working artificial receptor or complex can bind a second conformation of a protein. In an embodiment, the present working artificial receptor or complex can bind a first conformation of a protein, but not a second conformation of the same protein. In an embodiment, the present working artificial receptor or complex can bind a second conformation of a protein, but not a first conformation of the same protein.
For example, in an embodiment, the present working artificial receptor or complex can bind a first or non-infectious conformation of a prion, but not its second or infectious conformation. For example, in an embodiment, the present working artificial receptor or complex can bind the second or infectious conformation of a prion, but not its first or non-infectious conformation. For example, in an embodiment, the present working artificial receptor or complex can bind a first or non-plaque-forming conformation of β-amyloid, but not its second or plaque-forming conformation. For example, in an embodiment, the present working artificial receptor or complex can bind a second or plaque-forming conformation of β-amyloid, but not its second or non-plaque-forming conformation.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a desired conformation of a protein. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the desired conformation of the protein. The building blocks making up the artificial receptors can be naïve to the protein or its desired conformation. The desired conformation of the protein can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or characterizing or detecting the desired conformation of the protein.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a first or non-infectious conformation of a prion. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the first or non-infectious conformation of a prion. The building blocks making up the artificial receptors can be naïve to the prion. The first or non-infectious conformation of a prion can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or characterizing or detecting the first or non-infectious conformation of a prion.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a second or infectious conformation of a prion. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the second or infectious conformation of a prion. The building blocks making up the artificial receptors can be naïve to the test ligand. The second or infectious conformation of a prion can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or characterizing or detecting the second or infectious conformation of a prion.
In an embodiment, the present method includes developing receptors or a receptor system that can distinguish between the first or non-infectious conformation of a prion and the second or infectious conformation of the prion. Such a method can include selecting a working artificial receptor or complex can that bind the first or non-infectious conformation of a prion, but not the second or infectious conformation of the prion. This embodiment can include selecting a working artificial receptor or complex can that bind the second or infectious conformation of a prion, but not the first or non-infectious conformation of the prion. Employed together, these two sets of working artificial receptors or systems can characterize a biological sample as containing one or both forms of the prion.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a first or non-plaque-forming conformation of a β-amyloid. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the first or non-plaque-forming conformation of the β-amyloid. The building blocks making up the artificial receptors can be naïve to the β-amyloid. The first or non-plaque-forming conformation of the β-amyloid can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or characterizing or detecting the first or non-plaque-forming conformation of the β-amyloid.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a second or plaque-forming conformation of a β-amyloid. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the second or plaque-forming conformation of a β-amyloid. The building blocks making up the artificial receptors can be naïve to the β-amyloid. The second or plaque-forming conformation of the β-amyloid can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or characterizing or detecting the second or plaque-forming conformation of the β-amyloid.
In an embodiment, the present method includes developing receptors or a receptor system that can distinguish between the first or non-plaque-forming conformation of β-amyloid and the second or plaque-forming conformation of the β-amyloid. Such a method can include selecting a working artificial receptor or complex can that bind the first or non-plaque-forming conformation of β-amyloid, but not the second or plaque-forming conformation of the β-amyloid. This embodiment can include selecting a working artificial receptor or complex can that bind the second or plaque-forming conformation of the β-amyloid, but not the first or non-plaque-forming conformation of β-amyloid. Employed together, these two sets of working artificial receptors or systems can characterize a biological sample as containing one or both forms of the β-amyloid.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting cholera toxin. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the cholera toxin. The building blocks making up the artificial receptors can be naïve to the test ligand. The cholera toxin can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting cholera toxin.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting at least one protein of a cancer cell. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the cancer cell protein. The building blocks making up the artificial receptors can be naïve to the test ligand. The cancer cell protein can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or characterizing or detecting the cancer cell protein.
In an embodiment, the present method can include contacting a working artificial receptor or array with a sample from cells or tissues suspected of being cancerous or including a tumor. The sample can be serum. Binding of at least one protein to the working artificial receptor or array can indicate or characterize the presence of the particular cancer or tumor, such as by characterizing the pattern of proteins present.
Cancers that can be detected or characterized by such a method include, for example, bladder cancer, breast cancer, colon cancer, kidney cancer, liver cancer, lung cancer, including small cell lung cancer, esophageal cancer, gall-bladder cancer, ovarian cancer, pancreatic cancer, stomach cancer, cervical cancer, thyroid cancer, prostate cancer, and skin cancer, including squamous cell carcinoma; hematopoietic tumors of lymphoid lineage, including leukemia, acute lymphocytic leukemia, acute lymphoblastic leukemia, B-cell lymphoma, T-cell-lymphoma, Hodgkin's lymphoma, non-Hodgkin's lymphoma, hairy cell lymphoma and Burkett's lymphoma; hematopoietic tumors of myeloid lineage, including acute and chronic myelogenous leukemias, myelodysplastic syndrome and promyelocytic leukemia; tumors of mesenchymal origin, including fibrosarcoma and rhabdomyosarcoma; tumors of the central and peripheral nervous system, including astrocytoma, neuroblastoma, glioma and schwannomas; other tumors, including melanoma, seminoma, teratocarcinoma, osteosarcoma, xeroderoma pigmentosum, keratoctanthoma, thyroid follicular cancer, Kaposi's sarcoma, and the like.

Methods of Binding or Detecting Microbes

In an embodiment, the invention can include methods and/or devices for binding or detecting a microbe, e.g., cell or virus. Methods and systems for detection can include methods and systems for clinical chemistry, environmental analysis, and diagnostic assays of all types. For example, the artificial receptor can be contacted with a sample including or suspected of including at least one microbe, e.g., cell or virus. The building blocks making up the artificial receptors can be naïve to the test ligand. Then, binding of one or more of the microbes to the artificial receptors can be detected. Next, the binding results can be interpreted to provide information about the sample. In an embodiment, the invention includes a method for detecting a microbe, e.g., cell or virus, in a sample including contacting an artificial receptor specific to the microbe, e.g., cell or virus, with a sample suspected of containing the microbe, e.g., cell or virus. The method can also include detecting or quantitating binding of the microbe, e.g., cell or virus, to the artificial receptor.
FIG. 14 schematically illustrates an embodiment of a method for evaluating candidate artificial receptors for binding to a test ligand. This embodiment of the present method can be employed for detecting a test ligand such as a microbe, e.g., cell or virus. The method can include making an array of candidate artificial receptors. The building blocks making up the artificial receptors can be naïve to the test ligand. Working artificial receptors can be identified by contacting the array with a microbe, e.g., cell or virus, and identifying which receptors bind the microbe. The method can include producing an array or device including the working artificial receptor or receptor complex. In an embodiment, the method can include employing the array or device for detecting or characterizing the microbe, e.g., cell or virus, in a sample, such as a biological, laboratory, or environmental sample.
FIG. 15 schematically illustrates an embodiment of the present method employing an array of candidate artificial receptors. This embodiment of the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a microbe, e.g., cell or virus. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to a microbe, e.g., cell or virus. The building blocks making up the artificial receptors can be naïve to the test ligand. The microbe can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting the microbe, e.g., cell or virus.
FIG. 17 schematically illustrates an embodiment of a method for developing a method and system for detecting a test ligand, such as a disease causing organism. This embodiment of the present method includes evaluating a plurality (e.g. array) of candidate artificial receptors for binding to each of a plurality of test ligands, such as disease causing organisms. The building blocks making up the artificial receptors can be naïve to the test ligands. The method can include detecting binding of each test ligand (e.g., disease causing organism) to a subset of the plurality or array of candidate artificial receptors. This can be envisioned as developing a working artificial receptor or artificial receptor complex for each of the plurality of test ligands.
Thus, each test ligand (e.g., disease causing organism) can provide a pattern of bound receptors in the plurality or array. The pattern of bound receptors can be characteristic of the test ligand or a sample including the test ligand. The method can include storing a representation of the binding pattern as an image or a data structure. The representation of the binding pattern can be evaluated either by an operator or data processing system. The method can include such evaluating. A binding pattern from an unknown sample that matches the binding pattern for a particular test ligand (e.g., disease causing organism) then characterizes the unknown sample as containing that test ligand. Similarly, a binding pattern from an unknown sample can be evaluated against the patterns of a plurality of particular test ligands and the sample can be characterized as containing one or more of the test ligands. A plurality of binding patterns can be stored as a database.
An embodiment of the illustrated method can include creating an array of artificial receptors. This embodiment can also include compiling a database of the binding patterns of specific disease causing organisms, for example, by probing the array with a plurality of individual organisms. Contacting the array with an unidentified organism can create a test binding pattern. The method can then compare the test binding pattern with the binding patterns of known organisms in the database in order to characterize or classify the unidentified organism. In an embodiment, the database and the array of receptors has already been constructed and the method involves probing the array with an unknown organism to create a test binding pattern and then comparing this binding pattern with the binding patterns in the database in order to characterize or classify the unidentified organism.
In an embodiment, the method can include producing or employing the selected working artificial receptor or receptor complex on a substrate. The substrate can include working artificial receptors for a single microbe, e.g., cell or virus, or working artificial receptors for a plurality of microbes, e.g., cells or viruses. For example, a method can include contacting the artificial receptors with a sample. A substrate including working artificial receptors for a single microbe, e.g., cell or virus, can be employed in a method or system for detecting that microbe. Binding to the working artificial receptors indicates that the sample includes the microbe. A substrate including working artificial receptors for a plurality of microbes, e.g., cells or viruses can be employed in a method or system for detecting one, several, or all of the microbes. Binding to the working artificial receptors for a particular microbe or microbes indicates that the sample includes such a microbe or microbes.
The working artificial receptors or receptor complexes can be configured to provide a pattern indicative of the presence of one or more of the microbes, e.g., cells or viruses. The method can include detecting the binding pattern of the sample and comparing it with binding patterns from known samples. FIG. 16 schematically illustrates binding patterns on an array of working artificial receptors. Such patterns and schemes can be employed for identifying a variety of test ligands including microbes.
The present method can develop or employ a plurality of working receptors specific for a particular microbe or feature on the microbe. That is, the working receptors can be specific for a particular microbe, but different receptors can interact with different distinct antigens (e.g., proteins or carbohydrates), ligands, or features of the microbe. Such a method can provide a robust test for the presence of a microbe. For example, such a robust test can reduce the chances of a false-positive or false-negative result in comparison with an assay that relies upon a single unique receptor to detect a given microbe. Further, this embodiment of the method can develop or employ working receptors that demonstrate higher binding affinity due to interaction with multiple antigens or ligands on the same microbe (e.g., multivalent binding).
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a bacterium. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the bacterium. The building blocks making up the artificial receptors can be naïve to the test ligand. The bacterium can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or characterizing or detecting the bacterium.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a virus particle. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the virus particle. The building blocks making up the artificial receptors can be naïve to the test ligand. The virus particle can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample or for characterizing or detecting the virus particle.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a biohazard. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the biohazard. The building blocks making up the artificial receptors can be naïve to the test ligand. The biohazard can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting the biohazard.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting the Vibrio cholerae. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to V. cholerae. The building blocks making up the artificial receptors can be naïve to the V. cholerae. The V. cholerae can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting V. cholerae.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a microbe. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the microbe. The building blocks making up the artificial receptors can be naïve to the test ligand. One or more artificial receptors that bind the microbe under appropriate conditions can be selected for use on an affinity support that can bind that microbe. One or more artificial receptors that bind the microbe or cell sufficiently tightly under appropriate conditions can be selected and its building blocks incorporated onto a scaffold molecule. An embodiment of the method can employ a support with the one or more artificial receptors or scaffold-receptors on its surface for binding or immobilizing the microbe. A support with a plurality of artificial receptors, each binding to a different portion of the microbe, on its surface can be employed for multivalent capture or immobilization of the microbe.
The present method can include selecting artificial receptors that bind a particular microbe and/or the building blocks making up these receptors (e.g., bound to a scaffold molecule) as leads for pharmaceutical development or as active agents for modulating an activity of the microbe or as an antibiotic against that microbe.
In an embodiment, the method can employ an array including a significant number of the present artificial receptors to produce an assay or system for characterizing or detecting a microbe of clinical or environmental interest. The method can include evaluating an array including a significant number of candidate artificial receptors for binding to the microbe of clinical or environmental interest. The building blocks making up the artificial receptors can be naïve to the test ligand. The microbe of clinical or environmental interest can exhibit characteristic binding to one or several of the candidate artificial receptors from that array. The one or several artificial receptors can be selected as an artificial receptor (e.g., a working artificial receptor or a working artificial receptor complex) that can be employed in methods for characterizing a biological sample, or characterizing or detecting the microbe of clinical or environmental interest.
Suitable microbes of clinical or environmental interest include bacteria, mycoplasma, fungus, rickettsia, or virus. Suitable bacteria or mycoplasma of clinical or environmental interest include Escherichia coli (e.g., E. coli H157:07), Vibrio cholerae, Acinetobacter caicoaceticus, Haemophilus influenzae, Actinobacillus actinoides, Haemophilus parahaemolyticus, Actinobacillus lignieresii, Haemophilus parainfluenzae, Actinobacillus suis, Legionella pneumophila, Actinomyces bovis, Leptospira interrogans, Actinomyces israelli, Mima polymorphs, Aeromonas hydrophile, Moraxella lacunata, Arachnia propionica, Burkholderia mallei, Burkholderia pseudomallei, Moraxella osioensis, Arizona hinshawii, Mycobacterium osioensis, Bacillus cereus, Mycobacterium leprae, Bacteroides spp, Mycobacterium spp, Bartonella bacilliformis, Plesiomonas shigelloides, Bordetella bronchiseptica, Proteus spp, Clostridium difficile, Pseudomonas aeruginosa, Clostridium sordellii, Salmonella cholerasuis, Clostridium tetani, Salmonella enteritidis, Corynebacterium diphtheriae, Salmonella typhi, Edwardsiella tarda, Serratia marcescens, Enterobacter aerogenes, Shigella spp, Staphylococcus epidermidis, Francisella novicida, Vibrio parahaemolyticus, Haemophilus ducreyi, Haemophilus gallinarum, Haemophilus haemolyticus, Bacillus anthracis, Mycobacterium bovis, Bordetella pertussis, Mycobacterium tuberculosis, Borrella burgdorfii, Mycoplasma pneumoniae, Borrella spp, Neisseria gonorrhoeae, Campylobacter, Neisseria meningitides, Chlamydia psittaci, Nocardia asteroids, Chlamydia trachomatis, Nocardia brasillensis, Clostridium botulinum, Pasteurella haemolytica, Clostridium chauvoei, Pasteurelia multocida, Clostridium haemolyticus, Pasteurella pneumotropica, Clostridium histolyticum, Pseudomonas pseudomallei, Clostridium novyl, Staphylococcus aureus, Clostridium perfringens, Streptobacillus moniliformis, Clostridium septicum, Cyclospora cayatanensis, Streptococcus agalacetiae, Erysipelothrix insidiosa, Streptococcus pneumoniae, Klebsiella pneumoniae, Streptococcus pyogenes, Listeria manocytogenes, Yersinia pestis, Yersinia pseudotuberculosis, Yersinia enterocolitica, Brucella abortus, Brucella canis, Brucella melitensis, Brucella suis, and Francisella tularensis.
Suitable fungus include Absidia, Piedraia hortae, Aspergillus, Prototheca, Candida, Paecilomyces, Cryptococcus neoformans, Cryptosporidium parvum, Phialaphora, Dermatophilus congolensis, Rhizopus, Epidermophyton, Scopulariopsis, Exophiala, Sporothrix schenkii, Fusarium, Trichophyton, Madurella mycetomi, Toxoplasma, Trichosporon, Microsporum, Microsporidia, Wangiella dermatitidis, Mucor, Blastomyces dermatitidis, Giardia lamblia, Entamoeba histolytica, Coccidioides immitis, and Histoplasma capsulatum.
Suitable rickettsia or viruses of clinical or environmental interest include Coronaviruses, Hepatitis viruses, Hepatitis A virus, Myxo-Paramyxoviruses (Influenza viruses, Measles virus, Mumps virus, Newcastle disease virus), Picornavirus (Coxsackie viruses, Echoviruses, Poliomyelitis virus), Rickettsia akari, Rochalimaea Quintana, Rochalimaea vinsonii, Norwalk Agent, Adenoviruses, Arenaviruses (Lymphocytic choriomenigitis, Viscerotrophic strains), Herpesvirus Group (Herpesvirus hominis, Cytomegalovirus, Epstein-Barr virus, Caliciviruses, Pseudo-rabies virus, Varicella virus), Human Immunodeficiency Virus, Parainfluenza viruses (Respiratory syncytial virus, Subsclerosing panencephalitis virus), Picornaviruses (Poliomyelitis virus), Poxviruses Variola, Cowpox virus (Molluscum contagiosum virus, Monkeypox virus, Orf virus, Paravaccinia virus, Tanapox virus, Vaccinia virus, Yabapox virus), Papovaviruses (SV 40 virus, B-K-virus), Spongiform Encephalopathy Viruses (Creutzfeld-Jacob agent, Kuru agent, BSE), Rhabdoviruses (Rabies virus), Tobaviruses (Rubella virus), Coxiella burnetii, Rickettsia canada, Rickettsia prowazekii, Rickettsia rickettsii, Rickettsia Tsutsugamushi, Rickettsia typhi (R. mooseri), Spotted Fever Group Agents, Vesicular Stomatis Virus (VSV), and Toga, Arena (e.g., LCM, Junin, Lassa, Marchupo, Guanarito, etc.), Bunya (e.g., hantavirus, Rift Valley Fever, etc.), Flaviruses (Dengue), and Filoviruses (e.g., Ebola, Marburg, etc.) of all types, Nipah virus, viral encephalitis agents, LaCrosse, Kyasanur Forest virus, Yellow fever, and West Nile virus.
Suitable microbes of clinical or environmental interest include Variola Viruses, Congo-Crimean hemorrhagic fever, Tick-borne encephalitis virus complex (Absettarov, Hanzalova, Hypr, Kumlinge, Kyasanur Forest disease, Omsk hemorrhagic fever, and Russian Spring-Summer Encephalitis), Marburg, Ebola, Junin, Lassa, Machupo, Herpesvirus simiae, Bluetongue, Louping III, Rift Valley fever (Zing a), Wesselsbron, Foot and Mouth Disease, Newcastle Disease, African Swine Fever, Vesicular exanthema, Swine vesicular disease, Rinderpest, African horse sickness, Avian influenza, and Sheep pox. Other components of interest include Ricinus communis.

Methods for Making and Using Affinity Supports

In an embodiment, a working artificial receptor or receptor complex can be employed to produce or as an affinity support for any of the test ligands described herein. For example, the present method can include a method for producing an affinity support for a test ligand. This method can include selecting a working artificial receptor or receptor complex that binds to the test ligand. This method can also include coupling the working artificial receptor or receptor complex to a support. FIG. 20 schematically illustrates an embodiment of such a method. The support can be suitable for use as an affinity support for, for example, chromatography, membrane filtration, electrophoresis (e.g., 1 or 2 dimensional electrophoresis), or the like.
The present method can include selecting artificial receptors that bind a particular test ligand and/or the building blocks making up these receptors (e.g., bound to a scaffold molecule) for isolation or analysis of a particular test ligand. The building blocks making up the artificial receptors can be naïve to the test ligand. For example, the artificial receptor can be employed as a receptor surface that can bind the test ligand and remove (e.g., purify) it from a mixture or biological sample.
Such a method can include contacting one or more candidate artificial receptors with a test ligand of interest. The building blocks making up the artificial receptors can be naïve to the test ligand. The method can include selecting one or more of the candidate artificial receptors that bind the test ligand as working artificial receptor(s). The method can then include employing the working artificial receptor(s) to make a receptor surface. Making a receptor surface can include coupling the building blocks making up the working artificial receptor(s) to a support. The support can have sufficient area to bind a significant quantity of the test ligand of interest. The support can be a chromatography support or medium. The support can be a plate, tube, or membrane. In an embodiment, binding of the test ligand of interest to the support can be followed by eluting the test ligand of interest from the support. Eluting can employ a wash with a pH, buffer, solvent, salt concentration, or ligand concentration effective to elute the test ligand of interest from the support.
FIG. 21 schematically illustrates evaluating an array of candidate artificial receptors for binding of a test ligand and selecting one or more working artificial receptors. The building blocks making up the artificial receptors can be naïve to the test ligand. FIG. 21 illustrates that a receptor surface employing such a working artificial receptor can be employed for binding a protein, immobilizing an antibody, binding a single enantiomer, or protecting a structural feature (e.g., a functional group) on a compound. In an embodiment, the receptor surface can bind more than one structural feature on the protein. In an embodiment, the working artificial receptor can be selected to bind the constant portion, rather than the variable portions, of an antibody. In an embodiment, the receptor surface can include a catalytic moiety that can catalyze a reaction of a functional group of the bound test ligand. Such a catalytic moiety can be a building block, for example, an organometallic building block.
The present method can include selecting artificial receptors that bind a particular isomer of a compound and/or the building blocks making up these receptors (e.g., bound to a scaffold molecule) for isolation or analysis of a particular isomer. For example, the artificial receptor can be employed as a receptor surface that can bind the isomer and remove (e.g., purify) it from a mixture or biological sample.
Such a method can include contacting one or more candidate artificial receptors with an isomer of interest. The building blocks making up the artificial receptors can be naïve to the test ligand. The method can include selecting one or more of the candidate artificial receptors that bind the isomer as working artificial receptor(s). The method can then include employing the working artificial receptor(s) to make a receptor surface. Making a receptor surface can include coupling the building blocks making up the working artificial receptor(s) to a support. The support can have sufficient area to bind a significant quantity of the isomer of interest. The support can be a chromatography support or medium. The support can be a plate, tube, or membrane. In an embodiment, binding of the isomer of interest to the support can be followed by eluting the isomer of interest from the support. Eluting can employ a wash with a pH, buffer, solvent, salt concentration, or ligand concentration effective to elute the isomer of interest from the support.
The present method can include selecting artificial receptors that bind or protect a particular structural feature of a compound and/or the building blocks making up these receptors (e.g., bound to a scaffold molecule) for isolation or analysis of the compound including the structural feature. For example, the artificial receptor can be employed as a receptor surface that can bind or protect the structural feature of the compound. Binding of the structural feature can be determined by lack of binding of an analogous compound the lacking the structural feature. Protection of the structural feature can be evaluated by that structural feature being unavailable to a, for example, solution phase reactive species when the compound is bound to the receptor surface.
Such a method can include contacting one or more candidate artificial receptors with a compound of interest. The building blocks making up the artificial receptors can be naïve to the test ligand. The method can include selecting one or more of the candidate artificial receptors that bind the structural feature of the compound as lead artificial receptor(s). The lead artificial receptor can be evaluated for protecting the structural feature. The method can then include employing the working artificial receptor(s) to make a receptor surface. Making a receptor surface can include coupling the building blocks making up the working artificial receptor(s) to a support. The support can have sufficient area to bind a significant quantity of the compound of interest. In an embodiment, binding of the compound of interest to the support can be followed by reacting a portion of the compound that is not the bound or protected structure feature.
The present method can include selecting artificial receptors that bind a particular peptide or protein and/or the building blocks making up these receptors (e.g., bound to a scaffold molecule) for isolation or analysis of a particular peptide or protein. For example, the artificial receptor can be employed as a receptor surface that can bind the peptide or protein and remove (e.g., purify) it from a mixture or biological sample.
Such a method can include contacting one or more candidate artificial receptors with a peptide or protein of interest. The building blocks making up the artificial receptors can be naïve to the test ligand. The method can include selecting one or more of the candidate artificial receptors that bind the peptide or protein as working artificial receptor(s). The method can then include employing the working artificial receptor(s) to make a receptor surface. Making a receptor surface can include coupling the building blocks making up the working artificial receptor(s) to a support. The support can have sufficient area to bind a significant quantity of the peptide or protein of interest. The support can be a chromatography support or medium. The support can be a plate, tube, or membrane. In an embodiment, binding of the peptide or protein of interest to the support can be followed by eluting the peptide or protein of interest from the support. Eluting can employ a wash with a pH, buffer, salt concentration, or ligand concentration effective to elute the peptide or protein of interest from the support.
In an embodiment, the present artificial receptors can be employed to form selective membranes. Such a selective membrane can be based on a molecular gate including an artificial receptor surface. For example, an artificial receptor surface can line the walls of pores in the membrane and either allow or block a target molecule from passing through the pores. For example, an artificial receptor surface can line the walls of pores in the membrane and act as “gatekeepers” on e.g. micro cantilevers/molecular cantilevers to allow gate opening or closing on binding of the target. The artificial receptors to be used in the selective membranes can be identified by exposing the target molecule to a plurality of distinct artificial receptors and then determining which ones it binds to. For example, the binding can be detected through any of the techniques described herein, including fluorescence.
In certain embodiments, the method can include producing one or more receptor surfaces, each receptor surface including building blocks from a working receptor for a particular test ligand. Such a method can include employing the receptor surface for chromatography of the test ligand. Chromatographing the test ligand against a plurality of such receptor surfaces can rank the affinity of the surfaces for the test ligand. Under a given set of conditions, the receptor surface that retains the chromatographed test ligand the longest exhibits the greatest affinity for the test ligand. The method can include selecting the receptor surface with suitable (e.g., the greatest) affinity for use as an affinity support for the test ligand.
Any of a variety of supports can be employed as the affinity support. In certain embodiments, the affinity support can be a dish, a tube, a well, a bead, a chromatography support, a microchannel, or the like. The artificial receptor affinity support can be used in various applications, such as chromatography, microchannel devices, as an immunoassay support, or the like. A microchannel with the artificial receptor on its surface can be employed as an analytical device. In an embodiment, the present artificial receptors can be employed to form bioactive surfaces. For example, receptor surfaces can be used to specifically bind antibodies or enzymes.

Methods for Making and Using Reaction Supports

In an embodiment, a working artificial receptor or receptor complex can be employed to produce or as a reaction support for any of the test ligands described herein. For example, the present method can include a method for producing a reaction support for at least one test ligand. This method can include selecting a working artificial receptor or receptor complex that binds to the test ligand under conditions suitable for a desired reaction with that test ligand. This method can also include coupling the working artificial receptor or receptor complex to a support. FIG. 20 schematically illustrates an embodiment of such a method. The support can be suitable for use as a reaction support for, for example, oxidation, reduction, substitution, or displacement reactions.
The present method can include selecting artificial receptors that bind a particular test ligand and/or the building blocks making up these receptors (e.g., bound to a scaffold molecule) for reaction of a particular test ligand. For example, the artificial receptor can be employed as a receptor surface that can bind the test ligand and position it for reaction at a particular prochiral group, functional group, or orientation.
Such a method can include contacting one or more candidate artificial receptors with a test ligand of interest. The building blocks making up the artificial receptors can be naïve to the test ligand. The method can include selecting one or more of the candidate artificial receptors that bind the test ligand as working artificial receptor(s). The method can then include employing the working artificial receptor(s) to make a receptor surface. Making a receptor surface can include coupling the building blocks making up the working artificial receptor(s) to a support. The support can have sufficient area to bind a desired quantity of the test ligand of interest. The support can be a chromatography support or medium. The support can be a plate, bead, tube, or membrane.
The method also includes contacting the support including bound test ligand with a reactant for the desired reaction. Suitable reactants include reducing agent, oxidizing agent, nucleophile, electrophile, solvent (e.g., aqueous or organic solvent), or the like. The method can include contacting with one or more reactants and selecting reactant or reactants suitable for participating in the desired reaction. This embodiment of the method includes reacting the test ligand with the reactant. In an embodiment, reacting can be followed by washing the reactant or side products from the support. In an embodiment, reacting can be followed by eluting the product (e.g., reacted test ligand) from the support. Eluting can employ a wash with a pH, buffer, solvent, salt concentration, or ligand concentration effective to elute the product from the support.
FIG. 21 schematically illustrates evaluating an array of candidate artificial receptors for binding of a test ligand and selecting one or more working artificial receptors. The building blocks making up the artificial receptors can be naïve to the test ligand. FIG. 21 illustrates that a receptor surface employing such a working artificial receptor can be employed for binding a test ligand. The test ligand can be bound in an orientation that leaves a reactive moiety available for reaction with a reactant placed into contact with the receptor surface. In an embodiment, the test ligand can be bound in an orientation that occludes or protects a second reactive moiety from reacting with the reactant. This embodiment includes reacting the test ligand and release of the reacted test ligand from the receptor surface. Specifically, the illustration shows the reduction of an aldehyde with sodium borohydride to produce an alcohol. In an embodiment, the receptor surface can include a catalytic moiety that can catalyze a reaction of a functional group of the bound to test ligand the catalytic reaction can also employ the reactant. Such a catalytic moiety can be a building block, for example, an organometallic building block.
The present method can include selecting artificial receptors that bind or protect a particular structural feature of a compound and/or the building blocks making up these receptors (e.g., bound to a scaffold molecule) for reacting the compound including the structural feature. For example, the artificial receptor can be employed as a receptor surface that can bind and protect the structural feature of the compound while another feature of the compound reacts with a reactant. Protection of the structural feature can be evaluated by that structural feature not reacting with the reactant. For example, a substrate (e.g. a steroid) can be stereospecifically bound to the artificial receptor and present a particular moiety/sub-structure/“face” for reaction with a reagent in solution.
In an embodiment, a first side of a molecule (or a functional group) is bound to a receptor surface while a second side is left exposed. Then a reagent is added that could react with either side (or group) but is hindered from reacting with the first side of the molecule since it is bound to the receptor surface, accordingly the reagent reacts with the second side of the molecule only.
Such a method can include contacting one or more candidate artificial receptors with a compound of interest. The method can include selecting one or more of the candidate artificial receptors that bind the structural feature of the compound as lead artificial receptor(s). The lead artificial receptor can be evaluated for protecting the structural feature. The method can then include employing the working artificial receptor(s) to make a receptor surface. Making a receptor surface can include coupling the building blocks making up the working artificial receptor(s) to a support. The support can have sufficient area to bind a desired quantity of the compound of interest. In an embodiment, binding of the compound of interest to the support can be followed by reacting a portion of the compound that is not the bound or protected structure feature.
Conventional synthesis of a chiral compound generally requires complicated procedures. In an embodiment, the present candidate artificial receptors can be employed to find receptor surfaces that provide a spatially oriented binding surface for a stereospecific reaction. For example, an artificial receptor surface can bind a small molecule so that particular functional groups are exposed to the environment, and others are obscured by the receptor. In this manner, the stereospecificity of the reaction can be controlled. Therefore, an artificial receptor surface can be employed in synthesis including chiral induction. Similarly, regiospecificity can also be controlled using receptors of the present invention.
The present method can include selecting artificial receptors that bind a first reaction ligand and a second reaction ligand or the building blocks making up these receptors (e.g., bound to a scaffold molecule) for a reaction including the first and second reaction ligands. For example, the artificial receptor can be employed as a receptor surface that can bind the first reaction ligand and the second reaction ligand at a distance or orientation at which these ligands can react with one another. The reaction can optionally include one or more reactants not bound to the receptor surface.
Such a method can include contacting one or more candidate artificial receptors with a first reaction ligand and a second reaction ligand. The building blocks making up the artificial receptors can be naïve to the ligands. The method can include selecting one or more of the candidate artificial receptors that bind both of the reaction ligands as working artificial receptor(s). The method can then include employing the working artificial receptor(s) to make a receptor surface. Making a receptor surface can include coupling the building blocks making up the working artificial receptor(s) to a support. The support can have sufficient area to bind a desired quantity of the first and second reaction ligands. The support can be a chromatography support or medium. The support can be a plate, bead, tube, or membrane. The first and second reaction ligands can be bound to the support at one or several molar ratios, the reaction evaluated, and a molar ratio selected for conducting the reaction.
The method can also include contacting the support including bound reaction ligands with a reactant for the desired reaction. Suitable reactants include reducing agent, oxidizing agent, nucleophile, electrophile, or the like. This embodiment of the method includes reacting the test ligand with the reactant. In an embodiment, reacting can be followed by washing the reactant or side products from the support. In an embodiment, the first and second reaction ligands react without the reactant. In an embodiment, reacting can be followed by eluting the product (e.g., reacted test ligand) from the support. Eluting can employ a wash with a pH, buffer, solvent, salt concentration, or ligand concentration effective to elute the product from the support.
In an embodiment, the present candidate artificial receptors can be employed to find receptor surfaces that provide a spatially oriented binding surface for a stereospecific reaction. For example, an artificial receptor surface can bind a small molecule with particular functional groups exposed to the environment, and others obscured by the receptor. Such an artificial receptor surface can be employed in synthesis including chiral induction. For example, a substrate (e.g. a steroid) can be stereospecifically bound to the artificial receptor and present a particular moiety/sub-structure/“face” for reaction with a reagent in solution. Similarly, the artificial receptor surface can act as a protecting group where a reactive moiety of a molecule is “protected” by binding to the receptor surface so that a different moiety with similar reactivity can be transformed.
In an embodiment, the one or more working artificial receptors that bind a plurality (e.g., 2) of the reactants can be produced on a substrate and the reactants bound. Each receptor with a plurality of bound reactants can then be screened against one or more reagents or conditions (e.g., various molar ratios of the reactants or various solvents). The artificial receptor allowing or promoting reaction between the two or more reactants can be identified. The artificial receptor can then be produced on a substrate to provide a reactor for the reaction of interest.
Any of a variety of supports can be employed as the reaction support. In certain embodiments, the reaction support can be a dish, a tube, a well, a bead, a chromatography support, a microchannel, or the like. The artificial receptor reaction support can be used in various applications, such as a microchannel device. A microchannel with the artificial receptor on its surface can be employed as a reactor.

Methods of Making an Artificial Receptor

The present invention relates to a method of making an artificial receptor or a candidate artificial receptor. In an embodiment, this method includes preparing a spot or region on a support, the spot or region including a plurality of building blocks immobilized on the support. The method can include forming a plurality of spots on a solid support, each spot including a plurality of building blocks, and immobilizing (e.g., reversibly) a plurality of building blocks on the solid support in each spot. In an embodiment, an array of such spots is referred to as a heterogeneous building block array.
The method can include mixing a plurality of building blocks and employing the mixture in forming the spot(s). Alternatively, the method can include spotting individual building blocks on the support. Coupling building blocks to the support can employ covalent bonding or noncovalent interactions. Suitable noncovalent interactions include interactions between ions, hydrogen bonding, van der Waals interactions, and the like. In an embodiment, the support can be functionalized with moieties that can engage in covalent bonding or noncovalent interactions. Forming spots can yield a microarray of spots of heterogeneous combinations of building blocks, each of which can be a candidate artificial receptor. The method can apply or spot building blocks onto a support in combinations of 2, 3, 4, or more building blocks.
In an embodiment, the present method can be employed to produce a solid support having on its surface a plurality of regions or spots, each region or spot including a plurality of building blocks. For example, the method can include spotting a glass slide with a plurality of spots, each spot including a plurality of building blocks. Such a spot can be referred to as including heterogeneous building blocks. A plurality of spots of building blocks can be referred to as an array of spots.
In an embodiment, the present method includes making a receptor surface. Making a receptor surface can include forming a region on a solid support, the region including a plurality of building blocks, and immobilizing (e.g., reversibly) the plurality of building blocks to the solid support in the region. The method can include mixing a plurality of building blocks and employing the mixture in forming the region or regions. Alternatively, the method can include applying individual building blocks in a region on the support. Forming a region on a support can be accomplished, for example, by soaking a portion of the support with the building block solution. The resulting coating including building blocks can be referred to as including heterogeneous building blocks.
A region including a plurality of building blocks can be independent and distinct from other regions including a plurality of building blocks. In an embodiment, one or more regions including a plurality of building blocks can overlap to produce a region including the combined pluralities of building blocks. In an embodiment, two or more regions including a single building block can overlap to form one or more regions each including a plurality of building blocks. The overlapping regions can be envisioned, for example, as portions of overlap in a Ven diagram, or as portions of overlap in a pattern like a plaid or tweed.
In an embodiment, the method produces a spot or surface with a density of building blocks sufficient to provide interactions of more than one building block with a ligand. That is, the building blocks can be in proximity to one another. Proximity of different building blocks can be detected by determining different (e.g., greater) binding of a test ligand to a spot or surface including a plurality of building blocks compared to a spot or surface including only one of the building blocks.
In an embodiment, the method includes forming an array of heterogeneous spots made from combinations of a subset of the total building blocks and/or smaller groups of the building blocks in each spot. That is, the method forms spots including only, for example, 2 or 3 building blocks, rather than 4 or 5. For example, the method can form spots from combinations of a full set of building blocks (e.g. 81 of a set of 81) in groups of 2 and/or 3. For example, the method can form spots from combinations of a subset of the building blocks (e.g., 25 of the set of 81) in groups of 4 or 5. For example, the method can form spots from combinations of a subset of the building blocks (e.g., 25 of a set of 81) in groups of 2 or 3. The method can include forming additional arrays incorporating building blocks, lead artificial receptors, or structurally similar building blocks.
In an embodiment, the method includes forming an array including one or more spots that function as controls for validating or evaluating binding to artificial receptors of the present invention. In an embodiment, the method includes forming one or more regions, tubes, or wells that function as controls for validating or evaluating binding to artificial receptors of the present invention. Such a control spot, region, tube, or well can include no building block, only a single building block, only functionalized lawn, or combinations thereof.
The method can immobilize (e.g., reversibly) building blocks on supports using known methods for immobilizing compounds of the types employed as building blocks. Coupling building blocks to the support can employ covalent bonding or noncovalent interactions. Suitable noncovalent interactions include interactions between ions, hydrogen bonding, van der Waals interactions, and the like. In an embodiment, the support can be functionalized with moieties that can engage in reversible covalent bonding, moieties that can engage in noncovalent interactions, a mixture of these moieties, or the like.
In an embodiment, the support can be functionalized with moieties that can engage in covalent bonding, e.g., reversible covalent bonding. The present invention can employ any of a variety of the numerous known functional groups, reagents, and reactions for forming reversible covalent bonds. Suitable reagents for forming reversible covalent bonds include those described in Green, T W; Wuts, P G M (1999), Protective Groups in Organic Synthesis Third Edition, Wiley-Interscience, New York, 779 pp. For example, the support can include functional groups such as a carbonyl group, a carboxyl group, a silane group, boric acid or ester, an amine group (e.g., a primary, secondary, or tertiary amine, a hydroxylamine, a hydrazine, or the like), a thiol group, an alcohol group (e.g., primary, secondary, or tertiary alcohol), a diol group (e.g., a 1,2 diol or a 1,3 diol), a phenol group, a catechol group, or the like. These functional groups can form groups with reversible covalent bonds, such as ether (e.g., alkyl ether, silyl ether, thioether, or the like), ester (e.g., alkyl ester, phenol ester, cyclic ester, thioester, or the like), acetal (e.g., cyclic acetal), ketal (e.g., cyclic ketal), silyl derivative (e.g., silyl ether), boronate (e.g., cyclic boronate), amide, hydrazide, imine, carbamate, or the like. Such a functional group can be referred to as a covalent bonding moiety, e.g., a first covalent bonding moiety.
A carbonyl group on the support and an amine group on a building block can form an imine or Schiff's base. The same is true of an amine group on the support and a carbonyl group on a building block. A carbonyl group on the support and an alcohol group on a building block can form an acetal or ketal. The same is true of an alcohol group on the support and a carbonyl group on a building block. A thiol (e.g., a first thiol) on the support and a thiol (e.g., a second thiol) on the building block can form a disulfide.
A carboxyl group on the support and an alcohol group on a building block can form an ester. The same is true of an alcohol group on the support and a carboxyl group on a building block. Any of a variety of alcohols and carboxylic acids can form esters that provide covalent bonding that can be reversed in the context of the present invention. For example, reversible ester linkages can be formed from alcohols such as phenols with electron withdrawing groups on the aryl ring, other alcohols with electron withdrawing groups acting on the hydroxyl-bearing carbon, other alcohols, or the like; and/or carboxyl groups such as those with electron withdrawing groups acting on the acyl carbon (e.g., nitrobenzylic acid, R—CF₂—COOH, R—CCl₂—COOH, and the like), other carboxylic acids, or the like.
In an embodiment, the support, matrix, or lawn can be functionalized with moieties that can engage in noncovalent interactions. For example, the support can include functional groups such as an ionic group, a group that can hydrogen bond, or a group that can engage in van der Waals or other hydrophobic interactions. Such functional groups can include cationic groups, anionic groups, lipophilic groups, amphiphilic groups, and the like.
In an embodiment, the support, matrix, or lawn includes a charged moiety (e.g., a first charged moiety). Suitable charged moieties include positively charged moieties and negatively charged moieties. Suitable positively charged moieties (e.g., at neutral pH in aqueous compositions) include amines, quaternary ammonium moieties, ferrocene, or the like. Suitable negatively charged moieties (e.g., at neutral pH in aqueous compositions) include carboxylates, phenols substituted with strongly electron withdrawing groups (e.g., tetrachlorophenols), phosphates, phosphonates, phosphinates, sulphates, sulphonates, thiocarboxylates, hydroxamic acids, or the like.
In an embodiment, the support, matrix, or lawn includes groups that can hydrogen bond (e.g., a first hydrogen bonding group), either as donors or acceptors. The support, matrix, or lawn can include a surface or region with groups that can hydrogen bond. For example, the support, matrix, or lawn can include a surface or region including one or more carboxyl groups, amine groups, hydroxyl groups, carbonyl groups, or the like. Ionic groups can also participate in hydrogen bonding.
In an embodiment, the support, matrix, or lawn includes a lipophilic moiety (e.g., a first lipophilic moiety). Suitable lipophilic moieties include branched or straight chain C_6-36alkyl, C_8-24alkyl, C_12-24alkyl, C_12-18alkyl, or the like; C_6-36alkenyl, C_8-24alkenyl, C_12-24alkenyl, C_12-18alkenyl, or the like, with, for example, 1 to 4 double bonds; C_6-36alkynyl, C_8-24alkynyl, C_12-24alkynyl, C_12-18alkynyl, or the like, with, for example, 1 to 4 triple bonds; chains with 1-4 double or triple bonds; chains including aryl or substituted aryl moieties (e.g., phenyl or naphthyl moieties at the end or middle of a chain); polyaromatic hydrocarbon moieties; cycloalkane or substituted alkane moieties with numbers of carbons as described for chains; combinations or mixtures thereof; or the like. The alkyl, alkenyl, or alkynyl group can include branching; within chain functionality like an ether group; terminal functionality like alcohol, amide, carboxylate or the like; or the like. A lipophilic moiety like a quaternary ammonium lipophilic moiety can also include a positive charge.

Artificial Receptors

A candidate artificial receptor, a lead artificial receptor, or a working artificial receptor includes combination of building blocks immobilized (e.g., reversibly) on, for example, a support. An individual artificial receptor can be a heterogeneous building block spot on a slide or a plurality of building blocks coated on a slide, tube, or well. The building blocks can be immobilized through any of a variety of interactions, such as covalent, electrostatic, or hydrophobic interactions. For example, the building block and support or lawn can each include one or more functional groups or moieties that can form covalent, electrostatic, hydrogen bonding, van der Waals, or like interactions.
An array of candidate artificial receptors can be a commercial product sold to parties interested in using the candidate artificial receptors as implements in developing receptors for test ligands of interest. In an embodiment, a useful array of candidate artificial receptors includes at least one glass slide, the at least one glass slide including spots of a predetermined number of combinations of members of a set of building blocks, each combination including a predetermined number of building blocks.
One or more lead artificial receptors can be developed from a plurality of candidate artificial receptors. In an embodiment, a lead artificial receptor includes a combination of building blocks and binds detectable quantities of test ligand upon exposure to, for example, several picomoles of test ligand at a concentration of 1, 0.1, or 0.01 μg/ml, or at 1, 0.1, or 0.01 ng/ml test ligand; at a concentration of 0.01 μg/ml, or at 1, 0.1, or 0.01 ng/ml test ligand; or a concentration of 1, 0.1, or 0.01 ng/ml test ligand.
Artificial receptors, particularly candidate or lead artificial receptors, can be in the form of an array of artificial receptors. Such an array can include, for example, 1.66 million spots, each spot including one combination of 4 building blocks from a set of 81 building blocks. Such an array can include, for example, 28,000 spots, each spot including one combination of 2, 3, or 4 building blocks from a set of 29 building blocks. Each spot is a candidate artificial receptor and a combination of building blocks. The array can also be constructed to include lead artificial receptors. For example, the array of artificial receptors can include combinations of fewer building blocks and/or a subset of the building blocks.
In an embodiment, an array of candidate artificial receptors includes building blocks of general Formula 2 (shown hereinbelow), with RE₁being B1, B2, B3, B3a, B4, B5, B6, B7, B8, or B9 (shown hereinbelow) and with RE₂being A1, A2, A3, A3a, A4, A5, A6, A7, A8, or A9 (shown hereinbelow). In an embodiment, the framework is tyrosine.
One or more working artificial receptors can be developed from one or more lead artificial receptors. In an embodiment, a working artificial receptor includes a combination of building blocks and binds categorizing or identifying quantities of test ligand upon exposure to, for example, several picomoles of test ligand at a concentration of 100, 10, 1, 0.1, 0.01, or 0.001 ng/ml test ligand; at a concentration of 10, 1, 0.1, 0.01, or 0.001 ng/ml test ligand; or a concentration of 1, 0.1, 0.01, or 0.001 ng/ml test ligand.
In an embodiment, the artificial receptor of the invention includes a plurality of building blocks coupled to a support. In an embodiment, the plurality of building blocks can include or be building blocks of Formula 2 (shown below). An abbreviation for the building block including a linker, a tyrosine framework, and recognition elements AxBy is TyrAxBy. In an embodiment, a candidate artificial receptor can include combinations of building blocks of formula TyrA1B1, TyrA2B2, TyrA2B4, TyrA2B6, TyrA2B8, TyrA3B3, TyrA4B2, TyrA4B4, TyrA4B6, TyrA4B8, TyrA5B5, TyrA6B2, TyrA6B4, TyrA6B6, TyrA6B8, TyrA7B7, TyrA8B2, TyrA8B4, TyrA8B6, or TyrA8B8.
The present artificial receptors can employ any of a variety of supports to which building blocks or other array materials can be coupled. For example, the support can be glass or plastic; a slide, a tube, or a well; an optical fiber; a nanotube or a buckyball, a nanodevice; a dendrimer, or a scaffold; or the like.
The present artificial receptors can include a signal element that produces a detectable signal when a test ligand is bound to the receptor. In an embodiment, the signal element can produce an optical signal or a electrochemical signal. Suitable optical signals include chemiluminescence or fluorescence. The signal element can be a fluorescent moiety. The fluorescent molecule can be one that is quenched by binding to the artificial receptor. For example, the signal element can be a molecule that fluoresces only when binding occurs. Suitable electrochemical signal elements include those that give rise to current or a potential. Suitable electrochemical signal elements include phenols and anilines, such as those with substitutents oriented ortho or para to one another, polynuclear aromatic hydrocarbons, sulfide-disulfide, sulfide-sulfoxide-sulfone, polyenes, polyeneynes, and the like. Suitable electrochemical signal elements include quinones and ferrocenes.

Building Blocks

The present invention relates to building blocks for making or forming candidate artificial receptors. Building blocks can be designed, made, and selected to provide a variety of structural characteristics among a small number of compounds. A building block can provide one or more structural characteristics such as positive charge, negative charge, acid, base, electron acceptor, electron donor, hydrogen bond donor, hydrogen bond acceptor, free electron pair, π electrons, charge polarization, hydrophilicity, hydrophobicity, and the like. A building block can be bulky or it can be small.
A building block can be visualized as including several components, such as one or more frameworks, one or more linkers, and/or one or more recognition elements. The framework can be covalently coupled to each of the other building block components. The linker can be covalently coupled to the framework. The linker can be coupled to a support through one or more of covalent, electrostatic, hydrogen bonding, van der Waals, or like interactions. The recognition element can be covalently coupled to the framework. In an embodiment, a building block includes a framework, a linker, and a recognition element. In an embodiment, a building block includes a framework, a linker, and two recognition elements.
A description of general and specific features and functions of a variety of building blocks and their synthesis can be found in copending U.S. patent application Ser. Nos. 10/244,727, filed Sep. 16, 2002, 10/813,568, filed Mar. 29, 2004, and Application No. PCT/US03/05328, filed Feb. 19, 2003, each entitled “ARTIFICIAL RECEPTORS, BUILDING BLOCKS, AND METHODS”; U.S. patent application Ser. Nos. 10/812,850 and 10/813,612, and application No. PCT/US2004/009649, each filed Mar. 29, 2004 and each entitled “ARTIFICIAL RECEPTORS INCLUDING REVERSIBLY IMMOBILIZED BUILDING BLOCKS, THE BUILDING BLOCKS, AND METHODS”; and U.S. Provisional Patent Application Nos. 60/499,965, filed Sep. 3, 2003, and 60/526,699, filed Dec. 2, 2003, each entitled BUILDING BLOCKS FOR ARTIFICIAL RECEPTORS; the disclosures of which are incorporated herein by reference. These patent documents include, in particular, a detailed written description of: function, structure, and configuration of building blocks, framework moieties, recognition elements, synthesis of building blocks, specific embodiments of building blocks, specific embodiments of recognition elements, and sets of building blocks.

Framework

The framework can be selected for functional groups that provide for coupling to the recognition moiety and for coupling to or being the linking moiety. The framework can interact with the ligand as part of the artificial receptor. In an embodiment, the framework includes multiple reaction sites with orthogonal and reliable functional groups and with controlled stereochemistry. Suitable functional groups with orthogonal and reliable chemistries include, for example, carboxyl, amine, hydroxyl, phenol, carbonyl, and thiol groups, which can be individually protected, deprotected, and derivatized. In an embodiment, the framework has two, three, or four functional groups with orthogonal and reliable chemistries. In an embodiment, the framework has three functional groups. In such an embodiment, the three functional groups can be independently selected, for example, from carboxyl, amine, hydroxyl, phenol, carbonyl, or thiol group. The framework can include alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, and like moieties.
A general structure for a framework with three functional groups can be represented by Formula 1a:
A general structure for a framework with four functional groups can be represented by Formula 1b:
In these general structures: R₁can be a 1-12, a 1-6, or a 1-4 carbon alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, or like group; and F₁, F₂, F₃, or F₄can independently be a carboxyl, amine, hydroxyl, phenol, carbonyl, or thiol group. F₁, F₂, F₃, or F₄can independently be a 1-12, a 1-6, a 1-4 carbon alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, or inorganic group substituted with carboxyl, amine, hydroxyl, phenol, carbonyl, or thiol group. F₃and/or F₄can be absent.
A variety of compounds fit the formulas and text describing the framework including amino acids, and naturally occurring or synthetic compounds including, for example, oxygen and sulfur functional groups. The compounds can be racemic, optically active, or achiral. For example, the compounds can be natural or synthetic amino acids, α-hydroxy acids, thioic acids, and the like.
Suitable molecules for use as a framework include a natural or synthetic amino acid, particularly an amino acid with a functional group (e.g., third functional group) on its side chain. Amino acids include carboxyl and amine functional groups. The side chain functional group can include, for natural amino acids, an amine (e.g., alkyl amine, heteroaryl amine), hydroxyl, phenol, carboxyl, thiol, thioether, or amidino group. Natural amino acids suitable for use as frameworks include, for example, serine, threonine, tyrosine, aspartic acid, glutamic acid, asparagine, glutamine, cysteine, lysine, arginine, histidine. Synthetic amino acids can include the naturally occurring side chain functional groups or synthetic side chain functional groups which modify or extend the natural amino acids with alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, and like moieties as framework and with carboxyl, amine, hydroxyl, phenol, carbonyl, or thiol functional groups. Suitable synthetic amino acids include β-amino acids and homo or β analogs of natural amino acids. In an embodiment, the framework amino acid can be serine, threonine, or tyrosine, e.g., serine or tyrosine, e.g., tyrosine.
Although not limiting to the present invention, a framework amino acid, such as serine, threonine, or tyrosine, with a linker and two recognition elements can be visualized with one of the recognition elements in a pendant orientation and the other in an equatorial orientation, relative to the extended carbon chain of the framework.
All of the naturally occurring and many synthetic amino acids are commercially available. Further, forms of these amino acids derivatized or protected to be suitable for reactions for coupling to recognition element(s) and/or linkers can be purchased or made by known methods (see, e.g., Green, T W; Wuts, P G M (1999), Protective Groups in Organic Synthesis Third Edition, Wiley-Interscience, New York, 779 pp.; Bodanszky, M.; Bodanszky, A. (1994), The Practice of Peptide Synthesis Second Edition, Springer-Verlag, New York, 217 pp.).

Recognition Element

The recognition element can be selected to provide one or more structural characteristics to the building block. The recognition element can interact with the ligand as part of the artificial receptor. For example, the recognition element can provide one or more structural characteristics such as positive charge, negative charge, acid, base, electron acceptor, electron donor, hydrogen bond donor, hydrogen bond acceptor, free electron pair, π electrons, charge polarization, hydrophilicity, hydrophobicity, and the like. A recognition element can be a small group or it can be bulky.
In an embodiment the recognition element can be a 1-12, a 1-6, or a 1-4 carbon alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, or like group. The recognition element can be substituted with a group that includes or imparts positive charge, negative charge, acid, base, electron acceptor, electron donor, hydrogen bond donor, hydrogen bond acceptor, free electron pair, π electrons, charge polarization, hydrophilicity, hydrophobicity, and the like.
Recognition elements with a positive charge (e.g., at neutral pH in aqueous compositions) include amines, quaternary ammonium moieties, sulfonium, phosphonium, ferrocene, and the like. Suitable amines include alkyl amines, alkyl diamines, heteroalkyl amines, aryl amines, heteroaryl amines, aryl alkyl amines, pyridines, heterocyclic amines (saturated or unsaturated, the nitrogen in the ring or not), amidines, hydrazines, and the like. Alkyl amines generally have 1 to 12 carbons, e.g., 1-8, and rings can have 3-12 carbons, e.g., 3-8. Suitable alkyl amines include that of formula B9. Suitable heterocyclic or alkyl heterocyclic amines include that of formula A9. Suitable pyridines include those of formulas A5 and B5. Any of the amines can be employed as a quaternary ammonium compound. Additional suitable quaternary ammonium moieties include trimethyl alkyl quaternary ammonium moieties, dimethyl ethyl alkyl quaternary ammonium moieties, dimethyl alkyl quaternary ammonium moieties, aryl alkyl quaternary ammonium moieties, pyridinium quaternary ammonium moieties, and the like.
Recognition elements with a negative charge (e.g., at neutral pH in aqueous compositions) include carboxylates, phenols substituted with strongly electron withdrawing groups (e.g., substituted tetrachlorophenols), phosphates, phosphonates, phosphinates, sulphates, sulphonates, thiocarboxylates, and hydroxamic acids. Suitable carboxylates include alkyl carboxylates, aryl carboxylates, and aryl alkyl carboxylates. Suitable phosphates include phosphate mono-, di-, and tri-esters, and phosphate mono-, di-, and tri-amides. Suitable phosphonates include phosphonate mono- and di-esters, and phosphonate mono- and di-amides (e.g., phosphonamides). Suitable phosphinates include phosphinate esters and amides.
Recognition elements with a negative charge and a positive charge (at neutral pH in aqueous compositions) include sulfoxides, betaines, and amine oxides.
Acidic recognition elements can include carboxylates, phosphates, sulphates, and phenols. Suitable acidic carboxylates include thiocarboxylates. Suitable acidic phosphates include the phosphates listed hereinabove.
Basic recognition elements include amines. Suitable basic amines include alkyl amines, aryl amines, aryl alkyl amines, pyridines, heterocyclic amines (saturated or unsaturated, the nitrogen in the ring or not), amidines, and any additional amines listed hereinabove. Suitable alkyl amines include that of formula B9. Suitable heterocyclic or alkyl heterocyclic amines include that of formula A9. Suitable pyridines include those of formulas A5 and B5.
Recognition elements including a hydrogen bond donor include amines, amides, carboxyls, protonated phosphates, protonated phosphonates, protonated phosphinates, protonated sulphates, protonated sulphinates, alcohols, and thiols. Suitable amines include alkyl amines, aryl amines, aryl alkyl amines, pyridines, heterocyclic amines (saturated or unsaturated, the nitrogen in the ring or not), amidines, ureas, and any other amines listed hereinabove. Suitable alkyl amines include that of formula B9. Suitable heterocyclic or alkyl heterocyclic amines include that of formula A9. Suitable pyridines include those of formulas A5 and B5. Suitable protonated carboxylates, protonated phosphates include those listed hereinabove. Suitable amides include those of formulas A8 and B8. Suitable alcohols include primary alcohols, secondary alcohols, tertiary alcohols, and aromatic alcohols (e.g., phenols). Suitable alcohols include those of formulas A7 (a primary alcohol) and B7 (a secondary alcohol).
Recognition elements including a hydrogen bond acceptor or one or more free electron pairs include amines, amides, carboxylates, carboxyl groups, phosphates, phosphonates, phosphinates, sulphates, sulphonates, alcohols, ethers, thiols, and thioethers. Suitable amines include alkyl amines, aryl amines, aryl alkyl amines, pyridines, heterocyclic amines (saturated or unsaturated, the nitrogen in the ring or not), amidines, ureas, and amines as listed hereinabove. Suitable alkyl amines include that of formula B9. Suitable heterocyclic or alkyl heterocyclic amines include that of formula A9. Suitable pyridines include those of formulas A5 and B5. Suitable carboxylates include those listed hereinabove. Suitable amides include those of formulas A8 and B8. Suitable phosphates, phosphonates and phosphinates include those listed hereinabove. Suitable alcohols include primary alcohols, secondary alcohols, tertiary alcohols, aromatic alcohols, and those listed hereinabove. Suitable alcohols include those of formulas A7 (a primary alcohol) and B7 (a secondary alcohol). Suitable ethers include alkyl ethers, aryl alkyl ethers. Suitable alkyl ethers include that of formula A6. Suitable aryl alkyl ethers include that of formula A4. Suitable thioethers include that of formula B6.
Recognition elements including uncharged polar or hydrophilic groups include amides, alcohols, ethers, thiols, thioethers, esters, thio esters, boranes, borates, and metal complexes. Suitable amides include those of formulas A8 and B8. Suitable alcohols include primary alcohols, secondary alcohols, tertiary alcohols, aromatic alcohols, and those listed hereinabove. Suitable alcohols include those of formulas A7 (a primary alcohol) and B7 (a secondary alcohol). Suitable ethers include those listed hereinabove. Suitable ethers include that of formula A6. Suitable aryl alkyl ethers include that of formula A4.
Recognition elements including uncharged hydrophobic groups include alkyl (substituted and unsubstituted), alkene (conjugated and unconjugated), alkyne (conjugated and unconjugated), aromatic. Suitable alkyl groups include lower alkyl, substituted alkyl, cycloalkyl, aryl alkyl, and heteroaryl alkyl. Suitable lower alkyl groups include those of formulas A1, A3, A3a, and B1. Suitable aryl alkyl groups include those of formulas A3, A3a, A4, B3, B3a, and B4. Suitable alkyl cycloalkyl groups include that of formula B2. Suitable alkene groups include lower alkene and aryl alkene. Suitable aryl alkene groups include that of formula B4. Suitable aromatic groups include unsubstituted aryl, heteroaryl, substituted aryl, aryl alkyl, heteroaryl alkyl, alkyl substituted aryl, and polyaromatic hydrocarbons. Suitable aryl alkyl groups include those of formulas A3, A3a and B4. Suitable alkyl heteroaryl groups include those of formulas A5 and B5.
Spacer (e.g., small) recognition elements include hydrogen, methyl, ethyl, and the like. Bulky recognition elements include 7 or more carbon or hetero atoms.
Formulas A1-A9 and B1-B9 are:
These A and B recognition elements can be called derivatives of, according to a standard reference: A1, ethylamine; A2, isobutylamine; A3, phenethylamine; A4, 4-methoxyphenethylamine; A5,2-(2-aminoethyl)pyridine; A6,2-methoxyethylamine; A7, ethanolamine; A8, N-acetylethylenediamine; A9,1-(2-aminoethyl)pyrrolidine; B1, acetic acid, B2, cyclopentylpropionic acid; B3,3-chlorophenylacetic acid; B4, cinnamic acid; B5, 3-pyridinepropionic acid; B6, (methylthio)acetic acid; B7,3-hydroxybutyric acid; B8, succinamic acid; and B9,4-(dimethylamino)butyric acid.
In an embodiment, the recognition elements include one or more of the structures represented by formulas A1, A2, A3, A3a, A4, A5, A6, A7, A8, and/or A9 (the A recognition elements) and/or B1, B2, B3, B3a, B4, B5, B6, B7, B8, and/or B9 (the B recognition elements). In an embodiment, each building block includes an A recognition element and a B recognition element. In an embodiment, a group of 81 such building blocks includes each of the 81 unique combinations of an A recognition element and a B recognition element. In an embodiment, the A recognition elements are linked to a framework at a pendant position. In an embodiment, the B recognition elements are linked to a framework at an equatorial position. In an embodiment, the A recognition elements are linked to a framework at a pendant position and the B recognition elements are linked to the framework at an equatorial position.
Although not limiting to the present invention, it is believed that the A and B recognition elements represent the assortment of functional groups and geometric configurations employed by polypeptide receptors. Although not limiting to the present invention, it is believed that the A recognition elements represent six advantageous functional groups or configurations and that the addition of functional groups to several of the aryl groups increases the range of possible binding interactions. Although not limiting to the present invention, it is believed that the B recognition elements represent six advantageous functional groups, but in different configurations than employed for the A recognition elements. Although not limiting to the present invention, it is further believed that this increases the range of binding interactions and further extends the range of functional groups and configurations that is explored by molecular configurations of the building blocks.
In an embodiment, the building blocks including the A and B recognition elements can be visualized as occupying a binding space defined by lipophilicity/hydrophilicity and volume. A volume can be calculated (using known methods) for each building block including the various A and B recognition elements. A measure of lipophilicity/hydrophilicity (logP) can be calculated (using known methods) for each building block including the various A and B recognition elements. Negative values of logP show affinity for water over nonpolar organic solvent and indicate a hydrophilic nature. A plot of volume versus logP can then show the distribution of the building blocks through a binding space defined by size and lipophilicity/hydrophilicity.
Reagents that form many of the recognition elements are commercially available. For example, reagents for forming recognition elements A1, A2, A3, A3a, A4, A5, A6, A7, A8, A9 B1, B2, B3, B3a, B4, B5, B6, B7, B8, and B9 are commercially available.

Linkers

The linker is selected to provide a suitable coupling of the building block to a support. The framework can interact with the ligand as part of the artificial receptor. The linker can also provide bulk, distance from the support, hydrophobicity, hydrophilicity, and like structural characteristics to the building block. Coupling building blocks to the support can employ covalent bonding or noncovalent interactions. Suitable noncovalent interactions include interactions between ions, hydrogen bonding, van der Waals interactions, and the like. In an embodiment, the linker includes moieties that can engage in covalent bonding or noncovalent interactions. In an embodiment, the linker includes moieties that can engage in covalent bonding. Suitable groups for forming covalent and reversible covalent bonds are described hereinabove.

Linkers for Reversibly Immobilizable Building Blocks

The linker can be selected to provide suitable reversible immobilization of the building block on a support or lawn. In an embodiment, the linker forms a covalent bond with a functional group on the framework. In an embodiment, the linker also includes a functional group that can reversibly interact with the support or lawn, e.g., through reversible covalent bonding or noncovalent interactions.
In an embodiment, the linker includes one or more moieties that can engage in reversible covalent bonding. Suitable groups for reversible covalent bonding include those described hereinabove. An artificial receptor can include building blocks reversibly immobilized on the lawn or support through, for example, imine, acetal, ketal, disulfide, ester, or like linkages. Such functional groups can engage in reversible covalent bonding. Such a functional group can be referred to as a covalent bonding moiety, e.g., a second covalent bonding moiety.
In an embodiment, the linker can be functionalized with moieties that can engage in noncovalent interactions. For example, the linker can include functional groups such as an ionic group, a group that can hydrogen bond, or a group that can engage in van der Waals or other hydrophobic interactions. Such functional groups can include cationic groups, anionic groups, lipophilic groups, amphiphilic groups, and the like.
In an embodiment, the present methods and compositions can employ a linker including a charged moiety (e.g., a second charged moiety). Suitable charged moieties include positively charged moieties and negatively charged moieties. Suitable positively charged moieties include amines, quaternary ammonium moieties, sulfonium, phosphonium, ferrocene, and the like. Suitable negatively charged moieties (e.g., at neutral pH in aqueous compositions) include carboxylates, phenols substituted with strongly electron withdrawing groups (e.g., tetrachlorophenols), phosphates, phosphonates, phosphinates, sulphates, sulphonates, thiocarboxylates, and hydroxamic acids.
In an embodiment, the present methods and compositions can employ a linker including a group that can hydrogen bond, either as donor or acceptor (e.g., a second hydrogen bonding group). For example, the linker can include one or more carboxyl groups, amine groups, hydroxyl groups, carbonyl groups, or the like. Ionic groups can also participate in hydrogen bonding.
In an embodiment, the present methods and compositions can employ a linker including a lipophilic moiety (e.g., a second lipophilic moiety). Suitable lipophilic moieties include one or more branched or straight chain C_6-36alkyl, C_8-24alkyl, C_12-24alkyl, C_12-18alkyl, or the like; C_6-36alkenyl, C_8-24alkenyl, C_12-24alkenyl, C_12-18alkenyl, or the like, with, for example, 1 to 4 double bonds; C_6-36alkynyl, C_8-24alkynyl, C_12-24alkynyl, C_12-18alkynyl, or the like, with, for example, 1 to 4 triple bonds; chains with 1-4 double or triple bonds; chains including aryl or substituted aryl moieties (e.g., phenyl or naphthyl moieties at the end or middle of a chain); polyaromatic hydrocarbon moieties; cycloalkane or substituted alkane moieties with numbers of carbons as described for chains; combinations or mixtures thereof; or the like. The alkyl, alkenyl, or alkynyl group can include branching; within chain functionality like an ether group; terminal functionality like alcohol, amide, carboxylate or the like; or the like. In an embodiment the linker includes or is a lipid, such as a phospholipid. In an embodiment, the lipophilic moiety includes or is a 12-carbon aliphatic moiety.
In an embodiment, the linker includes a lipophilic moiety (e.g., a second lipophilic moiety) and a covalent bonding moiety (e.g., a second covalent bonding moiety). In an embodiment, the linker includes a lipophilic moiety (e.g., a second lipophilic moiety) and a charged moiety (e.g., a second charged moiety).
In an embodiment, the linker forms or can be visualized as forming a covalent bond with an alcohol, phenol, thiol, amine, carbonyl, or like group on the framework. Between the bond to the framework and the group participating in or formed by the reversible interaction with the support or lawn, the linker can include an alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, ethoxy or propoxy oligomer, a glycoside, or like moiety.
For example, suitable linkers can include: the functional group participating in or formed by the bond to the framework, the functional group or groups participating in or formed by the reversible interaction with the support or lawn, and a linker backbone moiety. The linker backbone moiety can include about 4 to about 48 carbon or heteroatoms, about 8 to about 14 carbon or heteroatoms, about 12 to about 24 carbon or heteroatoms, about 16 to about 18 carbon or heteroatoms, about 4 to about 12 carbon or heteroatoms, about 4 to about 8 carbon or heteroatoms, or the like. The linker backbone can include an alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, ethoxy or propoxy oligomer, a glycoside, mixtures thereof, or like moiety.
In an embodiment, the linker includes a lipophilic moiety, the functional group participating in or formed by the bond to the framework, and, optionally, one or more moieties for forming a reversible covalent bond, a hydrogen bond, or an ionic interaction. In such an embodiment, the lipophilic moiety can have about 4 to about 48 carbons, about 8 to about 14 carbons, about 12 to about 24 carbons, about 16 to about 18 carbons, or the like. In such an embodiment, the linker can include about 1 to about 8 reversible bond/interaction moieties or about 2 to about 4 reversible bond/interaction moieties. Suitable linkers have structures such as (CH₂)₁COOH, with n=12-24, n=17-24, or n=16-18.

Additional Embodiments of Linkers

The linker can be selected to provide a suitable covalent coupling of the building block to a support. The framework can interact with the ligand as part of the artificial receptor. The linker can also provide bulk, distance from the support, hydrophobicity, hydrophilicity, and like structural characteristics to the building block. In an embodiment, the linker forms a covalent bond with a functional group on the framework. In an embodiment, before attachment to the support the linker also includes a functional group that can be activated to react with or that will react with a functional group on the support. In an embodiment, once attached to the support, the linker forms a covalent bond with the support and with the framework.
In an embodiment, the linker forms or can be visualized as forming a covalent bond with an alcohol, phenol, thiol, amine, carbonyl, or like group on the framework. The linker can include a carboxyl, alcohol, phenol, thiol, amine, carbonyl, maleimide, or like group that can react with or be activated to react with the support. Between the bond to the framework and the group formed by the attachment to the support, the linker can include an alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, ethoxy or propoxy oligomer, a glycoside, or like moiety.
The linker can include a good leaving group bonded to, for example, an alkyl or aryl group. The leaving group being “good” enough to be displaced by the alcohol, phenol, thiol, amine, carbonyl, or like group on the framework. Such a linker can include a moiety represented by the formula: R—X, in which X is a leaving group such as halogen (e.g., —Cl, —Br or —I), tosylate, mesylate, triflate, and R is alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, ethoxy or propoxy oligomer, a glycoside, or like moiety.
Suitable linker groups include those of formula: (CH₂)₁COOH, with n=1-16, n=2-8, n=2-6, or n=3. Reagents that form suitable linkers are commercially available and include any of a variety of reagents with orthogonal functionality.

Embodiments of Building Blocks

In an embodiment, building blocks can be represented by Formula 2:
in which: RE₁is recognition element 1, RE₂is recognition element 2, and L is a linker. X is absent, C═O, CH₂, NR, NR₂, NH, NHCONH, SCONH, CH═N, or OCH₂NH. In certain embodiments, X is absent or C═O. Y is absent, NH, O, CH₂, or NRCO. In certain embodiments, Y is NH or O. In an embodiment, Y is NH. Z₁and Z₂can independently be CH₂, O, NH, S, CO, NR, NR₂, NHCONH, SCONH, CH═N, or OCH₂NH. In an embodiment, Z_iand/or Z₂can independently be O. Z₂is optional. R₂is H, CH₃, or another group that confers chirality on the building block and has size similar to or smaller than a methyl group. R₃is CH₂; CH₂-phenyl; CHCH₃; (CH₂)_nwith n=2-3; or cyclic alkyl with 3-8 carbons, e.g., 5-6 carbons, phenyl, naphthyl. In certain embodiments, R₃is CH₂or CH₂-phenyl.
RE₁is B1, B2, B3, B3a, B4, B5, B6, B7, B8, B9, A1, A2, A3, A3a, A4, A5, A6, A7, A8, or A9. In certain embodiments, RE₁is B1, B2, B3, B3a, B4, B5, B6, B7, B8, or B9. RE₂is A1, A2, A3, A3a, A4, A5, A6, A7, A8, A9, B1, B2, B3, B3a, B4, B5, B6, B7, B8, or B9. In certain embodiments, RE₂is A1, A2, A3, A3a, A4, A5, A6, A7, A8, or A9. In an embodiment, RE₁can be B2, B3a, B4, B5, B6, B7, or B8. In an embodiment, RE₂can be A2, A3a, A4, A5, A6, A7, or A8.
In an embodiment, L is the functional group participating in or formed by the bond to the framework (such groups are described herein), the functional group or groups participating in or formed by the reversible interaction with the support or lawn (such groups are described herein), and a linker backbone moiety. In an embodiment, the linker backbone moiety is about 4 to about 48 carbon or heteroatom alkyl, substituted alkyl, cycloalkyl, heterocyclic, substituted heterocyclic, aryl alkyl, aryl, heteroaryl, heteroaryl alkyl, ethoxy or propoxy oligomer, a glycoside, or mixtures thereof; or about 8 to about 14 carbon or heteroatoms, about 12 to about 24 carbon or heteroatoms, about 16 to about 18 carbon or heteroatoms, about 4 to about 12 carbon or heteroatoms, about 4 to about 8 carbon or heteroatoms.
In an embodiment, the L is the functional group participating in or formed by the bond to the framework (such groups are described herein) and a lipophilic moiety (such groups are described herein) of about 4 to about 48 carbons, about 8 to about 14 carbons, about 12 to about 24 carbons, about 16 to about 18 carbons. In an embodiment, this L also includes about 1 to about 8 reversible bond/interaction moieties (such groups are described herein) or about 2 to about 4 reversible bond/interaction moieties. In an embodiment, L is (CH₂)_nCOOH, with n=12-24, n=17-24, or n=16-18.
In an embodiment, L is (CH₂)_nCOOH, with n=1-16, n=2-8, n=4-6, or n=3.
Building blocks including an A and/or a B recognition element, a linker, and an amino acid framework can be made by methods illustrated in general Scheme 1.

Techniques for Using Artificial Receptors

The present invention includes a method of using artificial receptors. The present invention includes a method of screening candidate artificial receptors to find lead artificial receptors that bind a particular test ligand. Detecting test ligand bound to a candidate artificial receptor can be accomplished using known methods for detecting binding to arrays on a slide or to coated tubes or wells. For example, the method can employ test ligand labeled with a detectable label, such as a fluorophore or an enzyme that produces a detectable product. Alternatively, the method can employ an antibody (or other binding agent) specific for the test ligand and including a detectable label. One or more of the spots that are labeled by the test ligand or that are more or most intensely labeled with the test ligand are selected as lead artificial receptors. The degree of labeling can be evaluated by evaluating the signal strength from the label. The amount of signal can be directly proportional to the amount of label and binding. FIG. 13 provides a schematic illustration of an embodiment of this process.
According to the present method, screening candidate artificial receptors against a test ligand can yield one or more lead artificial receptors. One or more lead artificial receptors can be a working artificial receptor. That is, the one or more lead artificial receptors can be useful for detecting the ligand of interest as is. The method can then employ the one or more artificial receptors as a working artificial receptor for monitoring or detecting the test ligand. Alternatively, the one or more lead artificial receptors can be employed in the method for developing a working artificial receptor. For example, the one or more lead artificial receptors can provide structural or other information useful for designing or screening for an improved lead artificial receptor or a working artificial receptor. Such designing or screening can include making and testing additional candidate artificial receptors including combinations of a subset of building blocks, a different set of building blocks, or a different number of building blocks.
The present invention includes a method of screening candidate artificial receptors to find lead artificial receptors that bind a particular test ligand. The method can include allowing movement of the building blocks that make up the artificial receptors. Movement of building blocks can include mobilizing the building block to move along or on the support and/or to leave the support and enter a fluid (e.g., liquid) phase separate from the support or lawn.
In an embodiment, building blocks can be mobilized to move along or on the support (translate or shuffle). Such translation can be employed, for example, to allow building blocks already bound to a test ligand to rearrange into a lower energy or tighter binding configuration still bound to the test ligand. Such translation can be employed, for example, to allow the ligand access to building blocks that are on the support but not bound to the ligand. These building blocks can translate into proximity with and bind to a test ligand.
Building blocks can be induced to move along or on the support or to be reversibly immobilized on the support through any of a variety of mechanisms. For example, inducing mobility of building blocks can include altering the conditions of the support or lawn. That is, altering the conditions can reverse the immobilization of the building blocks, thus mobilizing them. Reversibly immobilizing the building blocks after they have moved can include, for example, returning to the previous conditions. Suitable alterations of conditions include changing pH, changing temperature, changing polarity or hydrophobicity, changing ionic strength, changing nucleophilicity or electrophilicity (e.g. of solvent or solute), and the like.
A building block reversibly immobilized by hydrophobic interactions can be mobilized by increasing the temperature, by exposing the surface, lawn, or building block to a more hydrophobic solvent (e.g., an organic solvent or a surfactant), or by reducing ionic strength around the building block. In an embodiment, the organic solvent includes acetonitrile, acetic acid, an alcohol, tetrahydrofuran (THF), dimethylformamide (DMF), hydrocarbons such as hexane or octane, acetone, chloroform, methylene chloride, or the like, or mixture thereof. In an embodiment, the surfactant includes a nonionic surfactant, such as a nonylphenol ethoxylate, or the like. A building block that is mobile on a support can be reversibly immobilized by hydrophobic interactions, for example, by decreasing the temperature, exposing the surface, lawn, or building block to a more hydrophilic solvent (e.g., an aqueous solvent) or increased ionic strength.
A building block reversibly immobilized by hydrogen bonding can be mobilized by increasing the ionic strength, concentration of hydrophilic solvent, or concentration of a competing hydrogen bonder in the environs of the building block. A building block that is mobile on a support can be reversibly immobilized through an electrostatic interaction by decreasing ionic strength of the hydrophilic solvent, or the like.
A building block reversibly immobilized by an electrostatic interaction can be mobilized by increasing the ionic strength in the environs of the building block. Increasing ionic strength can disrupt electrostatic interactions. A building block that is mobile on a support can be reversibly immobilized through an electrostatic interaction by decreasing ionic strength.
A building block reversibly immobilized by an imine, acetal, or ketal bond can be mobilized by decreasing the pH or increasing concentration of a nucleophilic catalyst in the environs of the building block. In an embodiment, the pH is about 1 to about 4. Imines, acetals, and ketals undergo acid catalyzed hydrolysis. A building block that is mobile on a support can be reversibly immobilized by a reversible covalent interaction, such as by forming an imine, acetal, or ketal bond, by increasing the pH.
In an embodiment, building blocks can be mobilized to leave the support and enter a fluid (e.g., liquid) phase separate from the support or lawn (exchange). For example, building blocks can be exchanged onto and/or off of the support. Exchange can be employed, for example, to allow building blocks on a support but not bound to a test ligand to be removed from the support. Exchange can be employed, for example, to add additional building blocks to the support. The added building blocks can have structures selected based on knowledge of the structures of the building blocks in artificial receptors that bind the test ligand. The added building blocks can have structures selected to provide additional structural diversity. The added building blocks can include all of the building blocks.
A building block reversibly immobilized by hydrophobic interactions can be released from the support by, for example, raising the temperature, e.g., of the support and/or artificial receptor. For example, the hydrophobic interactions (e.g., the hydrophobic group on the support or lawn and on the building block) can be selected to provide immobilized building block at about room temperature or below and release can be accomplished at a temperature above room temperature. For example, the hydrophobic interactions can be selected to provide immobilized building block at about refrigerator temperature (e.g., 4° C.) or below and release can be accomplished at a temperature of, for example, room temperature or above. By way of further example, a building block can be reversibly immobilized by hydrophobic interactions, for example, by contacting the surface or artificial receptor with a fluid containing the building block and that is at or below room temperature.
A building block reversibly immobilized by hydrophobic interactions can be released from the support by, for example, contacting the artificial receptor with a sufficiently hydrophobic fluid (e.g., an organic solvent or a surfactant). In an embodiment, the organic solvent includes acetonitrile, acetic acid, an alcohol, tetrahydrofuran (THF), dimethylformamide (DMF), hydrocarbons such as hexane or octane, acetone, chloroform, methylene chloride, or the like, or mixture thereof. In an embodiment, the surfactant includes a nonionic surfactant, such as a nonylphenol ethoxylate, or the like. Such reversible immobilization can also be effected by contacting the surface or artificial receptor with a hydrophilic solvent and allowing the somewhat lipophilic building block to partition on to the hydrophobic surface or lawn.
A building block reversibly immobilized by an imine, acetal, or ketal bond can be released from the support by, for example, contacting the artificial receptor with fluid having an acid pH or including a nucleophilic catalyst. In an embodiment, the pH is about 1 to about 4. A building block can be reversibly immobilized by a reversible covalent interaction, such as by forming an imine, acetal, or ketal bond, by contacting the surface or artificial receptor with fluid having a neutral or basic pH.
A building block reversibly immobilized by an electrostatic interaction can be released by, for example, contacting the artificial receptor with fluid having sufficiently high ionic strength to disrupt the electrostatic interaction. A building block can be reversibly immobilized through an electrostatic interaction by contacting the surface or artificial receptor with fluid having ionic strength that promotes electrostatic interaction between the building block and the support and/or lawn.

Test Ligands

The test ligand can be any ligand for which binding to an array or surface can be detected. The test ligand can be a pure compound, a mixture, or a “dirty” mixture containing a natural product or pollutant. Such dirty mixtures can be tissue homogenate, biological fluid, soil sample, water sample, or the like.
Test ligands include prostate specific antigen, other cancer markers, insulin, warfarin, other anti-coagulants, cocaine, other drugs-of-abuse, markers for E. coli, markers for Salmonella sp., markers for other food-borne toxins, food-borne toxins, markers for Smallpox virus, markers for anthrax, markers for other possible toxic biological agents, pharmaceuticals and medicines, pollutants and chemicals in hazardous waste, toxic chemical agents, markers of disease, pharmaceuticals, pollutants, biologically important cations (e.g., potassium or calcium ion), peptides, carbohydrates, enzymes, bacteria, viruses, mixtures thereof, and the like. In certain embodiments, the test ligand can be at least one of small organic molecules, inorganic/organic complexes, metal ion, mixture of proteins, protein, nucleic acid, mixture of nucleic acids, mixtures thereof, and the like.
Suitable test ligands include any compound or category of compounds described elsewhere in this document as being a test ligand, including, for example, the microbes, proteins, cancer cells, drugs of abuse, and the like described above.
The present invention may be better understood with reference to the following examples. These examples are intended to be representative of specific embodiments of the invention, and are not intended as limiting the scope of the invention.

EXAMPLES

Example 1

Synthesis of Building Blocks

Selected building blocks representative of the alkyl-aromatic-polar span of the an embodiment of the building blocks were synthesized and demonstrated effectiveness of these building blocks for making candidate artificial receptors. These building blocks were made on a framework that can be represented by tyrosine and included numerous recognition element pairs. These recognition element pairs were selected along the diagonal of Table 2, and include enough of the range from alkyl, to aromatic, to polar to represent a significant degree of the interactions and functional groups of the full set of 81 such building blocks.

Synthesis

Building block synthesis employed a general procedure outlined in Scheme 7, which specifically illustrates synthesis of a building block on a tyrosine framework with recognition element pair A4B4. This general procedure was employed for synthesis of building blocks including TyrA1B1 [1-1], TyrA2B2, TyrA2B4, TyrA2B6, TyrA2B8, TyrA4B2, TyrA4B4, TyrA4B6, TyrA4B8, TyrA6B2, TyrA6B4, TyrA6B6, TyrA6B8, TyrA8B2, TyrA8B4, TyrA8B6, TyrA8B8, and TyrA9B9, respectively.

Results

Synthesis of the desired building blocks proved to be generally straightforward. These syntheses illustrate the relative simplicity of preparing the building blocks with 2 recognition elements having different structural characteristics or structures (e.g. A4B2, A6B3, etc.) once the building blocks with corresponding recognition elements (e.g. A2B2, A4B4, etc) have been prepared via their X BOC intermediate.
The conversion of one of these building blocks to a building block with a lipophilic linker can be accomplished by reacting the activated building block with, for example, dodecyl amine.

Example 2

Preparation and Evaluation of Microarrays of Candidate Artificial Receptors

Microarrays of candidate artificial receptors were made and evaluated for binding several protein ligands. The results obtained demonstrate the 1) the simplicity with which microarrays of candidate artificial receptors can be prepared, 2) binding affinity and binding pattern reproducibility, 3) significantly improved binding for building block heterogeneous receptor environments when compared to the respective homogeneous controls, and 4) ligand distinctive binding patterns (e.g., working receptor complexes).

Materials and Methods

Building blocks were synthesized and activated as described in Example 1. The building blocks employed in this example were TyrA1B1 [1-1], TyrA2B2, TyrA2B4, TyrA2B6, TyrA4B2, TyrA4B4, TyrA4B6, TyrA6B2, TyrA6B4, and TyrA6B6. The abbreviation for the building block including a linker, a tyrosine framework, and recognition elements AxBy is TyrAxBy.
Microarrays for the evaluation of the 130 n=2 and n=3, and for evaluation of the 273 n=2, n=3, and n=4, candidate receptor environments were prepared as follows by modifications of known methods. Briefly: Amine modified (amine “lawn”; SuperAmine Microarray plates) microarray plates were purchased from Telechem Inc., Sunnyvale, Calif. (www.arrayit.com). These plates were manufactured specifically for microarray preparation and had a nominal amine load of 2-4 amines per square nm according to the manufacturer. The CAM microarrays were prepared using a pin microarray spotter instrument from Telechem Inc. (SpotBot™ Arrayer) typically with 200 um diameter spotting pins from Telechem Inc. (Stealth Micro Spotting Pins, SMP6) and 400-420 um spot spacing.
The 9 building blocks were activated in aqueous dimethylformamide (DMF) solution as described above. For preparing the 384-well feed plate, the activated building block solutions were diluted 10-fold with a solution of DMF/H₂O/PEG400 (90/10/10, v/v/v; PEG400 is polyethylene glycol nominal 400 FW, Aldrich Chemical Co., Milwaukee, Wis.). These stock solutions were aliquotted (10 μl per aliquot) into the wells of a 384-well microwell plate (Telechem Inc.). A separate series of controls were prepared by aliquotting 10 μl of building block with either 10 μl or 20 μl of the activated [1-1] solution. The plate was covered with aluminum foil and placed on the bed of a rotary shaker for 15 minutes at 1,000 RPM. This master plate was stored covered with aluminum foil at −20° C. when not in use.
For preparing the 384-well SpotBot™ plate, a well-to-well transfer (e.g. A-1 to A-1, A-2 to A-2, etc.) from the feed plate to a second 384-well plate was performed using a 4 μl transfer pipette. This plate was stored tightly covered with aluminum foil at −20° C. when not in use. The SpotBot™ was used to prepare up to 13 microarray plates per run using the 4 μl microwell plate. The SpotBot™ was programmed to spot from each microwell in quadruplicate. The wash station on the SpotBot™ used a wash solution of EtOH/H₂O (20/80, v/v). This wash solution was also used to rinse the microarrays on completion of the SpotBot™ printing run. The plates were given a final rinse with deionized (DI) water, dried using a stream of compressed air, and stored at room temperature.
Certain of the microarrays were further modified by reacting the remaining amines with succinic anhydride to form a carboxylate lawn in place of the amine lawn.
The following test ligands and labels were used in these experiments:
1) r-Phycoerythrin, a commercially available and intrinsically fluorescent protein with a FW of 2,000,000.
2) Ovalbumin labeled with the Alexa™ fluorophore (Molecular Probes Inc., Eugene, Oreg.).
3) BSA, bovine serum albumin, labeled with activated Rhodamine (Pierce Chemical, Rockford, Ill.) using the known activated carboxyl protocol. BSA has a FW of 68,000; the material used for this study had ca. 1.0 rhodamine per BSA.
4) Horseradish peroxidase (HRP) modified with extra amines and labeled as the acetamide derivative or with a 2,3,7,8-tetrachlorodibenzodixoin derivative were available through known methods. Fluorescence detection of these HRP conjugates was based on the Alexa 647-tyramide kit available from Molecular Probes, Eugene, Oreg.
5) Cholera toxin.
Microarray incubation and analysis was conducted as follows: For test ligand incubation with the microarrays, solutions (e.g. 500 μl) of the target proteins in PBS-T (PBS with 20 μl/L of Tween-20) at typical concentrations of 10, 1.0 and 0.1 μg/ml were placed onto the surface of a microarray and allowed to react for, e.g., 30 minutes. The microarray was rinsed with PBS-T and DI water and dried using a stream of compressed air.
The incubated microarray was scanned using an Axon Model 4200A Fluorescence Microarray Scanner (Axon Instruments, Union City, Calif.). The Axon scanner and its associated software produce a false color 16-bit image of the fluorescence intensity of the plate. This 16-bit data is integrated using the Axon software to give a Fluorescence Units value (range 0-65,536) for each spot on the microarray. This data is then exported into an Excel file (Microsoft) for further analysis including mean, standard deviation and coefficient of variation calculations.

Results

The CARA™: Combinatorial Artificial Receptor Array™ concept has been demonstrated using a microarray format. A CARA microarray based on N=9 building blocks was prepared and evaluated for binding to several protein and substituted protein ligands. This microarray included 144 candidate receptors (18 n=1 controls plus 6 blanks; 36 n=2 candidate receptors; 84 n=3 candidate receptors). This microarray demonstrated: 1) the simplicity of CARA microarray preparation, 2) binding affinity and binding pattern reproducibility, 3) significantly improved binding for building block heterogeneous receptor environments when compared to the respective homogeneous controls, and 4) ligand distinctive binding patterns.

Reading the Arrays

A typical false color/gray scale image of a microarray that was incubated with 2.0 μg/ml r-phycoerythrin is shown in FIG. 23. This image illustrates that the processes of both preparing the microarray and probing it with a protein test ligand produced the expected range of binding as seen in the visual range of relative fluorescence from dark to bright spots.
The starting point in analysis of the data was to take the integrated fluorescence units data for the array of spots and normalize to the observed value for the [1-1] building block control. Subsequent analysis included mean, standard deviation and coefficient of variation calculations. Additionally, control values for homogeneous building blocks were obtained from the building block plus [1-1] data.

First Set of Experiments

The following protein ligands were evaluated for binding to the candidate artificial receptors in the microarray. The resulting Fluorescence Units versus candidate receptor environment data is presented in both a 2D format where the candidate receptors are placed along the X-axis and the Fluorescence Units are shown on the Y-axis and a 3D format where the Candidate Receptors are placed in an X-Y format and the Fluorescence Units are shown on the Z-axis. A key for the composition of each spot was developed (not shown). A key for the building blocks in each of the 2D and 3D representations of the results was also developed (not shown). The data presented are for 1-2 μg/ml protein concentrations.
FIGS. 24 and 25 illustrate binding data for r-phycoerythrin (intrinsic fluorescence). FIGS. 26 and 27 illustrate binding data for ovalbumin (commercially available with fluorescence label). FIGS. 28 and 29 illustrate binding data for bovine serum albumin (labeled with rhodamine). FIGS. 30 and 31 illustrate binding data for HRP-NH-Ac (fluorescent tyramide read-out). FIGS. 32 and 33 illustrate binding data for HRP-NH-TCDD (fluorescent tyramide read-out).
These results demonstrate not only the application of the CARA microarray to candidate artificial receptor evaluation but also a few of the many read-out methods (e.g. intrinsic fluorescence, fluorescently labeled, in situ fluorescence labeling) which can be utilized for high throughput candidate receptor evaluation.
The evaluation of candidate receptors benefits from reproducibility. The following results demonstrate that the present microarrays provided reproducible ligand binding.
The microarrays were printed with each combination of building blocks spotted in quadruplicate. Visual inspection of a direct plot (FIG. 34) of the raw fluorescence data (from the run illustrated in FIG. 23) for one block of binding data obtained for r-phycoerythrin demonstrates that the candidate receptor environment “spots” showed reproducible binding to the test ligand. Further analysis of the r-phycoerythrin data (FIG. 23) led to only 9 out of 768 spots (1.2%) being deleted as outliers. Analysis of the r-phycoerythrin quadruplicate data for the entire array gives a mean standard deviation for each experimental quadruplicate set of 938 fluorescence units, with a mean coefficient of variation of 19.8%.
Although these values are acceptable, a more realistic comparison employed the standard deviation and coefficient of variation of the more strongly bound, more fluorescent receptors. The overall mean standard deviation unrealistically inflates the coefficient of variation for the weakly bound, less fluorescent receptors. The coefficient of variation for the 19 receptors with greater than 10,000 Fluorescent Units of bound target is 11.1%, which is well within the range required to produce meaningful binding data.
One goal of the CARA approach is the facile preparation of a significant number of candidate receptors through combinations of structurally simple building blocks. The following results establish that both the individual building blocks and combinations of building blocks have a significant, positive effect on test ligand binding.
The binding data illustrated in FIGS. 23-33 demonstrate that heterogeneous combinations of building blocks (n=2, n=3) are dramatically superior candidate receptors made from a single building block (n=1). For example, FIG. 25 illustrate both the diversity of binding observed for n=2, n=3 candidate receptors with fluorescent units ranging from 0 to ca. 40,000. These data also illustrate and the ca. 10-fold improvement in binding affinity obtained upon going from the homogeneous (n=1) to heterogeneous (n=2, n=3) receptor environments.
The effect of heterogeneous building blocks is most easily observed by comparing selected n=3 receptor environments candidate receptors including 1 or 2 of those building blocks (their n=2 and n=1 subsets). FIGS. 35 and 36 illustrate this comparison for two different n=3 receptor environments using the r-phycoerythrin data. In these examples, it is clear that progression from the homogeneous system (n=1) to the heterogeneous systems (n=2, n=3) produces significantly enhanced binding.
Although van der Waals interactions are an important part of molecular recognition, it is important to establish that the observed binding is not a simple case of hydrophobic/hydrophilic partitioning. That is, that the observed binding was the result of specific interactions between the individual building blocks and the target The simplest way to evaluate the effects of hydrophobicity and hydrophilicity is to compare building block logP value with observed binding. LogP is a known and accepted measure of lipophilicity, which can be measured or calculated by known methods for each of the building blocks. FIGS. 37 and 38 establish that the observed target binding, as measured by fluorescence units, is not directly proportional to building block logP. The plots in FIGS. 37 and 38 illustrate a non-linear relationship between binding (fluorescence units) and building block logP.
One advantage of the present methods and arrays is that the ability to screen large numbers of candidate receptor environments will lead to a combination of useful target affinities and to significant target binding diversity. High target affinity is useful for specific target binding, isolation, etc. while binding diversity can provide multiplexed target detection systems. This example employed a relatively small number of building blocks to produce ca. 120 binding environments. The following analysis of the present data clearly demonstrates that even a relatively small number of binding environments can produce diverse and useful artificial receptors.
The target binding experiments performed for this study used protein concentrations including 0.1 to 10 μg/ml. Considering the BSA data as representative, it is clear that some of the receptor environments readily bound 1.0 ug/ml BSA concentrations near the saturation values for fluorescence units (see, e.g., FIG. 29). Based on these data and the formula weight of 68,000 for BSA, several of the receptor environments readily bind BSA at ca. 15 picomole/ml or 15 nanomolar concentrations. Additional experiments using lower concentrations of protein (data not shown) indicate that, even with a small selection of candidate receptor environments, femptomole/ml or picomolar detection limits have been attained.
One goal of artificial receptor development is the specific recognition of a particular target. FIG. 39 compares the observed binding for r-phycoerythrin and BSA. Comparison of the overall binding pattern indicates some general similarities. However, comparison of specific features of binding for each receptor environment demonstrates that the two targets have distinctive recognition features as indicated by the (*) in FIG. 39.
One goal of artificial receptor development is to develop receptors which can be used for the multiplexed detection of specific targets. Comparison of the r-phycoerythrin, BSA and ovalbumin data from this study (FIGS. 25, 27, 29) were used to select representative artificial receptors for each target. FIGS. 40, 41 and 42 employ data obtained in the present example to illustrate identification of each of these three targets by their distinctive binding patterns.

Conclusions

The optimum receptor for a particular target requires molecular recognition which is greater than the expected sum of the individual hydrophilic, hydrophobic, ionic, etc. interactions. Thus, the identification of an optimum (specific, sensitive) artificial receptor from the limited pool of candidate receptors explored in this prototype study, was not expected and not likely. Rather, the goal was to demonstrate that all of the key components of the CARA: Combinatorial Artificial Receptor Array concept could be assembled to form a functional receptor microarray. This goal has been successfully demonstrated.
This study has conclusively established that CARA microarrays can be readily prepared and that target binding to the candidate receptor environments can be used to identify artificial receptors and test ligands. In addition, these results demonstrate that there is significant binding enhancement for the building block heterogeneous (n=2, n=3, or n=4) candidate receptors when compared to their homogeneous (n=1) counterparts. When combined with the binding pattern recognition results and the demonstrated importance of both the heterogeneous receptor elements and heterogeneous building blocks, these results clearly demonstrate the significance of the CARA Candidate Artificial Receptor−>Lead Artificial Receptor−>Working Artificial Receptor strategy.

Example 3

Preparation and Evaluation of Microarrays of Candidate Artificial Receptors Including Reversibly Immobilized Building Blocks

Microarrays of candidate artificial receptors including building blocks immobilized through van der Waals interactions were made and evaluated for binding of a protein ligand. The evaluation was conducted at several temperatures, above and below a phase transition temperature for the lawn (vide infra).

Materials and Methods

Building blocks 2-2, 2-4, 2-6, 4-2, 4-4, 4-6, 6-2, 6-4, 6-6 where prepared as described in Example 1. The C12 amide was prepared using the previously described carbodiimide activation of the carboxyl followed by addition of dodecylamine. This produced a building block with a 12 carbon alkyl chain linker for reversible immobilization in the C18 lawn.
Amino lawn microarray plates (Telechem) were modified to produce the C18 lawn by reaction of stearoyl chloride (Aldrich Chemical Co.) in A) dimethylformamide/PEG 400 solution (90:10, v/v, PEG 400 is polyethylene glycol average MW 400 (Aldrich Chemical Co.) or B) methylene chloride/TEA solution (100 ml methylene chloride, 200 μl triethylamine) using the lawn modification procedures generally described in Example 2.
The C18 lawn plates where printed using the SpotBot standard procedure as described in Example 2. The building blocks were in printing solutions prepared by solution of ca. 10 mg of each building block in 300 μl of methylene chloride and 100 μl methanol. To this stock was added 900 μl of dimethylformamide and 100 μl of PEG 400. The 36 combinations of the 9 building blocks taken two at a time (N9:n2, 36 combinations) where prepared in a 384-well microwell plate which was then used in the SpotBot to print the microarray in quadruplicate. A random selection of the print positions contained only print solution.
The selected microarray was incubated with a 1.0 μg/ml solution of the test ligand, cholera toxin subunit B labeled with the Alexa™ fluorophore (Molecular Probes Inc., Eugene, Oreg.), using the following variables: 1) the microarray was washed with methylene chloride, ethanol and water to create a control plate; and 2) the microarray was incubated at 4° C., 23° C., or 44° C. After incubation, the plate(s) were rinsed with water, dried and scanned (AXON 4100A). Data analysis was as described in Example 2.

Results

A control array from which the building blocks had been removed by washing with organic solvent did not bind cholera toxin (FIG. 43). FIGS. 44-46 illustrate fluorescence signals from arrays printed identically, but incubated with cholera toxin at 4° C., 23° C., or 44° C., respectively. Spots of fluorescence can be seen in each array, with very pronounced spots produced by incubation at 44° C. The fluorescence values for the spots in each of these three arrays are shown in FIGS. 47-49. Fluorescence signal generally increases with temperature, with many nearly equally large signals observed after incubation at 44° C. Linear increases with temperature can reflect expected improvements in binding with temperature. Nonlinear increases reflect rearrangement of the building blocks on the surface to achieve improved binding, which occurred above the phase transition for the lipid surface (vide infra).
FIG. 50 can be compared to FIG. 48. The fluorescence signals plotted in FIG. 48 resulted from binding to reversibly immobilized building blocks on a support at 23° C. The fluorescence signals plotted in FIG. 50 resulted from binding to covalently immobilized building blocks on a support at 23° C. These figures compare the same combinations of building blocks in the same relative positions, but immobilized in two different ways.
The binding to covalently immobilized building blocks was also evaluated at 4° C., 23° C., or 44° C. FIG. 51 illustrates the changes in fluorescence signal from individual combinations of covalently immobilized building blocks at 4° C., 23° C., or 44° C. Binding increased modestly with temperature. The mean increase in binding was 1.3-fold. A plot of the fluorescence signal for each of the covalently immobilized artificial receptors at 23° C. against its signal at 44° C. (not shown) yields a linear correlation with a correlation coefficient of 0.75. This linear correlation indicates that the mean 1.3-fold increase in binding is a thermodynamic effect and not optimization of binding.
FIG. 52 illustrates the changes in fluorescence signal from individual combinations of reversibly immobilized building blocks at 4° C., 23° C., or 44° C. This graph illustrates that at least one combination of building blocks (candidate artificial receptor) exhibited a signal that remained constant as temperature increased. At least one candidate artificial receptor exhibited an approximately linear increase in signal as temperature increased. Such a linear increase indicates normal temperature effects on binding. The candidate artificial receptor with the lowest binding signal at 4° C. became one of the best binders at 44° C. This indicates that rearrangement of the building blocks of this receptor above the phase transition for the lawn, which increases the building blocks' mobility, produced increased binding. Other receptors characterized by greater changes in binding between 23° C. and 44° C. (compared to between 4° C. and 23° C.) also underwent dynamic affinity optimization.
FIG. 53 illustrates the data presented in FIG. 51 (lines marked A) and the data presented in FIG. 52 (lines marked B). The increases in binding observed with the reversibly immobilized building blocks are significantly greater than the increases observed with covalently bound building blocks. Binding to reversibly immobilized building blocks increased from 23° C. and 44° C. by a median value of 6.1-fold and a mean value of 24-fold. This confirms that movement of the reversibly immobilized building blocks within the receptors increased binding (i.e., the receptor underwent dynamic affinity optimization).
A plot of the fluorescence signal for each of the reversibly immobilized artificial receptors at 23° C. against its signal at 44° C. (not shown) yields no correlation (correlation coefficient of 0.004). A plot of the fluorescence signal for each of the reversibly immobilized artificial receptors at 44° C. against the signal for the corresponding covalently immobilized receptor (not shown) also yields no correlation (correlation coefficient 0.004). This lack of correlation provides further evidence that movement of the reversibly immobilized building blocks within the receptors increased binding.
FIG. 54 illustrates a graph of the fluorescence signal at 44° C. divided by the signal at 23° C. against the fluorescence signal obtained from binding at 23° C. for the artificial receptors with reversibly immobilized receptors. This comparison indicates that the binding enhancement is independent of the initial affinity of the receptor for the test ligand.
Table 1 identifies the reversibly immobilized building blocks making up each of the artificial receptors, lists the fluorescence signal (binding strength) at 44° C. and 23° C., and the ratios of the observed binding at these two temperatures. These data illustrate that each artificial receptor reflects a unique attribute for each combination of building blocks relative to the role of each individual building block.

TABLE 1

Building Blocks
Making Up	Signal at		Ratio of Signals,
Receptor	44° C.	Signal at 23° C.	44° C./23° C.

22 24	24136	4611	5.23
22 26	16660	43	387.44
22 42	17287	−167	−103.51
22 44	16726	275	60.82
22 46	25016	3903	6.41
22 62	13990	3068	4.56
22 64	15294	3062	4.99
22 66	11980	3627	3.30
24 26	22688	1291	17.57
24 42	26808	−662	−40.50
24 44	23154	904	25.61
24 46	42197	2814	15.00
24 62	19374	2567	7.55
24 64	27599	262	105.34
24 66	16238	5334	3.04
26 42	22282	4974	4.48
26 44	26240	530	49.51
26 46	23144	4273	5.42
26 62	29022	4920	5.90
26 64	23416	5551	4.22
26 66	19553	5353	3.65
42 44	29093	6555	4.44
42 46	18637	3039	6.13
42 62	22643	4853	4.67
42 64	20836	6343	3.28
42 66	14391	9220	1.56
44 46	25600	3266	7.84
44 62	15544	4771	3.26
44 64	25842	3073	8.41
44 66	22471	5142	4.37
46 62	32764	8522	3.84
46 64	21901	3343	6.55
46 66	23516	3742	6.28
62 64	24069	7149	3.37
62 66	15831	2424	6.53
64 66	21310	2746	7.76

Conclusions

This experiment demonstrated that an array including reversibly immobilized building blocks binds a protein substrate, like an array with covalently immobilized building blocks. The binding increased nonlinearly as temperature increased, indicating that movement of the building blocks increased binding. Many of the candidate artificial receptors demonstrated improved binding upon mobilization of the building blocks.

Example 4

The Oligosaccharide Portion of GM1 Competes with Artificial Receptors for Binding to Cholera Toxin

Microarrays of candidate artificial receptors were made and evaluated for binding of cholera toxin. The arrays were also evaluated for disrupting that binding. Disrupting of binding employed a compound that binds to cholera toxin, the oligosaccharide moiety from GM1 (GM1 OS). The results obtained demonstrate that a ligand of a protein specifically disrupted binding of the protein to the microarray.

Materials and Methods

Building blocks were synthesized and activated as described in Example 1. The building blocks employed in this example were TyrA1B1 [1-1], TyrA2B2, TyrA2B4, TyrA2B6, TyrA2B8, TyrA3B3, TyrA3B5, TyrA3B7, TyrA4B2, TyrA4B4, TyrA4B6, TyrA4B8, TyrA5B3, TyrA5B5, TyrA5B7, TyrA6B2, TyrA6B4, TyrA6B6, TyrA6B8, TyrA7B3, TyrA7B5, TyrA7B7, TyrA8B2, TyrA8B4, TyrA8B6, and TyrA8B8. The abbreviation for the building block including a linker, a tyrosine framework, and recognition elements AxBy is TyrAxBy.
Microarrays for the evaluation of the 171 n=2 candidate receptor environments were prepared as follows by modifications of known methods. An “n=2” receptor environment includes two different building blocks. Briefly: Amine modified (amine “lawn”; SuperAmine Microarray plates) microarray plates were purchased from Telechem Inc., Sunnyvale, Calif. These plates were manufactured specifically for microarray preparation and had a nominal amine load of 2-4 amines per square nm according to the manufacturer. The microarrays were prepared using a pin microarray spotter instrument from Telechem Inc. (SpotBot™ Arrayer) typically with 200 μm diameter spotting pins from Telechem Inc. (Stealth Micro Spotting Pins, SMP6) and 400-420 μm spot spacing.
The 19 building blocks were activated in aqueous dimethylformamide (DMF) solution as described above. For preparing the 384-well feed plate, the activated building block solutions were diluted 10-fold with a solution of DMF/H₂O/PEG400 (90/10/10, v/v/v; PEG400 is polyethylene glycol nominal 400 FW, Aldrich Chemical Co., Milwaukee, Wis.). These stock solutions were aliquotted (10 μl per aliquot) into the wells of a 384-well microwell plate (Telechem Inc.). Control spots included the building block [1-1]. The plate was covered with aluminum foil and placed on the bed of a rotary shaker for 15 minutes at 1,000 RPM. This master plate was stored covered with aluminum foil at −20° C. when not in use.
For preparing the 384-well SpotBot™ plate, a well-to-well transfer (e.g. A-1 to A-1, A-2 to A-2, etc.) from the feed plate to a second 384-well plate was performed using a 4 μl transfer pipette. This plate was stored tightly covered with aluminum foil at −20° C. when not in use. The SpotBot™ was used to prepare up to 13 microarray plates per run using the 4 μl microwell plate. The SpotBot™ was programmed to spot from each microwell in quadruplicate. The wash station on the SpotBot™ used a wash solution of EtOH/H₂O (20/80, v/v). This wash solution was adjusted to pH 4 with 1 M HCl and used to rinse the microarrays on completion of the SpotBot™ printing run. The plates were given a final rinse with deionized (DI) water, dried using a stream of compressed air, and stored at room temperature. The microarrays were further modified by reacting the remaining amines with acetic anhydride to form an acetamide lawn in place of the amine lawn.
The test ligand employed in these experiments was cholera toxin labeled with the Alexa™ fluorophore (Molecular Probes Inc., Eugene, Oreg.). The candidate disruptor employed in these experiments was GM1 OS (GM1 oligosaccharide), a known ligand for cholera toxin.
Microarray incubation and analysis was conducted as follows: For control incubations with the microarrays, solutions (e.g. 500 μl) of the cholera toxin in PBS-T (PBS with 20 μl/L of Tween-20) at a concentrations of 1.7 pmol/ml (0.1 μg/ml) was placed onto the surface of a microarray and allowed to react for 30 minutes. For disruptor incubations with the microarrays, solutions (e.g. 500 μl) of the cholera toxin (1.7 pmol/ml, 0.1 μg/ml) and the desired concentration of GM1 OS in PBS-T (PBS with 20 μl/L of Tween-20) was placed onto the surface of a microarray and allowed to react for 30 minutes. GM1 OS was added at 0.34 and at 5.1 μM in separate experiments. After either of these incubations, the microarray was rinsed with PBS-T and DI water and dried using a stream of compressed air.
The incubated microarray was scanned using an Axon Model 4200A Fluorescence Microarray Scanner (Axon Instruments, Union City, Calif.). The Axon scanner and its associated software produce a false color 16-bit image of the fluorescence intensity of the plate. This 16-bit data is integrated using the Axon software to give a Fluorescence Units value (range 0-65,536) for each spot on the microarray. This data is then exported into an Excel file (Microsoft) for further analysis including mean, standard deviation and coefficient of variation calculations.
Table 2 identifies the building blocks in each of the first 150 receptor environments.

	TABLE 2

	Building Blocks

	1	22 24
	2	22 28
	3	22 42
	4	22 46
	5	22 55
	6	22 64
	7	22 68
	8	22 82
	9	22 86
	10	24 26
	11	24 33
	12	24 44
	13	26 77
	14	26 84
	15	26 88
	16	28 42
	17	22 26
	18	22 33
	19	22 44
	20	22 48
	21	22 62
	22	22 66
	23	22 77
	24	22 84
	25	22 88
	26	24 28
	27	24 42
	28	26 82
	29	26 85
	30	28 33
	31	28 44
	32	28 46
	33	28 55
	34	28 64
	35	28 68
	36	28 82
	37	28 86
	38	33 42
	39	33 46
	40	42 88
	41	44 48
	42	44 62
	43	44 66
	44	44 77
	45	44 84
	46	44 88
	47	46 55
	48	28 48
	49	28 62
	50	28 66
	51	28 77
	52	28 84
	53	28 88
	54	33 44
	55	44 46
	56	44 55
	57	44 64
	58	44 68
	59	44 82
	60	44 86
	61	46 48
	62	46 62
	63	24 46
	64	24 55
	65	24 64
	66	24 68
	67	24 82
	68	24 86
	69	26 28
	70	26 42
	71	26 46
	72	26 55
	73	26 64
	74	26 68
	75	33 48
	76	33 63
	77	33 66
	78	33 77
	79	24 48
	80	24 62
	81	24 66
	82	24 77
	83	24 84
	84	24 88
	85	26 33
	86	26 44
	87	26 48
	88	26 62
	89	26 66
	90	33 55
	91	33 64
	92	33 68
	93	33 82
	94	33 84
	95	33 88
	96	42 46
	97	42 55
	98	42 64
	99	42 68
	100	42 82
	101	42 86
	102	46 88
	103	48 62
	104	48 66
	105	46 77
	106	48 84
	107	48 88
	108	55 64
	109	55 68
	110	33 86
	111	42 44
	112	42 48
	113	42 62
	114	42 66
	115	42 77
	116	42 84
	117	48 55
	118	48 64
	119	48 68
	120	48 82
	121	48 86
	122	55 62
	123	55 66
	124	55 77
	125	46 64
	126	46 68
	127	46 82
	128	46 86
	129	62 77
	130	62 84
	131	62 88
	132	64 68
	133	64 82
	134	64 86
	135	66 68
	136	66 82
	137	66 86
	138	68 77
	139	68 84
	140	68 88
	141	46 66
	142	46 77
	143	46 84
	144	62 82
	145	62 86
	146	64 66
	147	64 77
	148	64 84
	149	64 88
	150	66 77

Results

Low Concentration of GM1 OS

FIG. 55 illustrates binding of cholera toxin to the microarray of candidate artificial receptors followed by washing with buffer produced fluorescence signals. These fluorescence signals demonstrate that the cholera toxin bound strongly to certain receptor environments, weakly to others, and undetectably to some. Comparison to experiments including those reported in Example 2 indicates that cholera toxin binding was reproducible from array to array and from month to month.
Binding of cholera toxin was also conducted with competition from GM1 OS (0.34 μM). FIG. 56 illustrates the fluorescence signals due to cholera toxin binding that were detected after this competition. Notably, many of the signals illustrated in FIG. 56 are significantly smaller than the corresponding signals recorded in FIG. 55. The small signals observed in FIG. 56 represent less cholera toxin bound to the array. GM1 OS significantly disrupted binding of cholera toxin to many of the receptor environments.
The disruption in cholera toxin binding caused by GM1 OS can be visualized as the ratio of the amount bound in the absence of GM1 OS to the amount bound in competition with GM1 OS. This ratio is illustrated in FIG. 57. The larger the ratio, the less cholera toxin remained bound to the artificial receptor after competition with GM1 OS. The ratio can be as large as about 30. The ratios are independent of the quantity bound in the control.

High Concentration of GM1 OS

Binding of cholera toxin to the microarray of candidate artificial receptors followed by washing with buffer produced fluorescence signals illustrated in FIG. 58. As before, cholera toxin was reproducible and it bound strongly to certain receptor environments, weakly to others, and undetectably to some. FIG. 59 illustrates the fluorescence signals detected due to cholera toxin binding that were detected upon competition with GM1 OS at 5.1 μM. Again, GM1 OS significantly disrupted binding of cholera toxin to many of the receptor environments.
This disruption is presented as the ratio of the amount bound in the absence of GM1 OS to the amount bound after contacting with GM1 OS in FIG. 60. The ratios range up to about 18 and are independent of the quantity bound in the control.

Conclusions

This experiment demonstrated that binding of a test ligand to an artificial receptor of the present invention can be diminished (e.g., competed) by a candidate disruptor molecule. In this case the test ligand was the protein cholera toxin and the candidate disruptor was a compound known to bind to cholera toxin, GM1 OS. The degree to which binding of the test ligand was disrupted was independent of the degree to which the test ligand bound to the artificial receptor.

Example 5

GM1 Competes With Artificial Receptors for Binding to Cholera Toxin

Microarrays of candidate artificial receptors were made and evaluated for binding of cholera toxin. The arrays were also evaluated for disrupting that binding. Disrupting of binding employed a compound that binds to cholera toxin, the liposaccharide GM1. The results obtained demonstrate that a ligand of a protein specifically disrupts binding of the protein to the microarray.

Materials and Methods

Building blocks were synthesized and activated as described in Example 1. The building blocks employed in this example were TyrA1B1 [1-1], TyrA2B2, TyrA2B4, TyrA2B6, TyrA4B2, TyrA4B4, TyrA4B6, TyrA6B2, TyrA6B4, and TyrA6B6 in groups of 4 building blocks per artificial receptor. The abbreviation for the building block including a linker, a tyrosine framework, and recognition elements AxBy is TyrAxBy.
Microarrays for the evaluation of the 126 n=4 candidate receptor environments were prepared as described above for Example 4. The test ligand employed in these experiments was cholera toxin labeled with the Alexa™ fluorophore (Molecular Probes Inc., Eugene, Oreg.). Cholera toxin was employed at 5.3 nM in both the control and the competition experiments. The candidate disruptor employed in these experiments was GM1, a known ligand for cholera toxin, which competed at concentrations of 0.042, 0.42, and 8.4 μM. Microarray incubation and analysis was conducted as described for Example 4.
Table 3 identifies the building blocks in each receptor environment.

	TABLE 3

	Building Blocks

	1	22 24 26 42
	2	22 24 26 44
	3	22 24 26 46
	4	22 24 26 61
	5	22 24 26 64
	6	22 24 26 66
	7	22 24 42 44
	8	22 24 42 46
	9	22 24 42 62
	10	22 24 42 46
	11	22 24 42 66
	12	22 24 44 46
	13	22 24 44 62
	14	22 24 44 64
	15	22 24 44 66
	16	22 24 46 62
	17	22 24 46 64
	18	22 24 46 66
	19	22 24 62 64
	20	22 24 62 66
	21	22 24 64 66
	22	22 26 42 44
	23	22 26 42 46
	24	22 26 42 62
	25	22 26 42 64
	26	22 26 42 66
	27	22 26 44 46
	28	22 26 44 62
	29	22 26 44 64
	30	22 26 44 66
	31	22 26 46 62
	32	22 26 46 64
	33	22 26 46 66
	34	22 26 62 64
	35	22 26 62 66
	36	22 26 64 66
	37	22 42 44 46
	38	22 42 44 62
	39	22 42 44 64
	40	22 42 44 66
	41	22 42 46 62
	42	22 42 46 64
	43	22 42 46 66
	44	22 42 62 64
	45	22 42 62 66
	46	22 42 64 66
	47	22 44 46 62
	48	22 44 46 64
	49	22 44 46 66
	50	22 44 62 64
	51	22 44 62 66
	52	22 44 64 66
	53	22 46 62 64
	54	22 46 62 66
	55	22 46 64 66
	56	22 62 64 66
	57	24 26 42 44
	58	24 26 42 46
	59	24 26 42 62
	60	24 26 42 64
	61	24 26 42 66
	62	24 26 44 46
	63	24 26 44 62
	64	24 26 44 64
	65	24 26 44 66
	66	24 26 46 62
	67	24 26 46 64
	68	24 26 46 66
	69	24 26 62 64
	70	24 26 62 66
	71	24 26 64 66
	72	24 42 44 46
	73	24 42 44 62
	74	24 42 44 64
	75	24 42 44 66
	76	24 42 46 62
	77	24 42 46 64
	78	24 42 46 66
	79	24 42 62 64
	80	24 42 62 66
	81	24 42 64 66
	82	24 44 46 62
	83	24 44 46 64
	84	24 44 46 66
	85	24 44 62 64
	86	24 44 62 66
	87	24 44 64 66
	88	24 46 62 64
	89	24 46 62 66
	90	24 46 64 66
	91	24 62 64 66
	92	26 42 44 46
	93	26 42 44 62
	94	26 42 44 64
	95	26 42 44 66
	96	26 42 46 62
	97	26 42 46 64
	98	26 42 46 66
	99	26 42 62 64
	100	26 42 62 66
	101	26 42 64 66
	102	26 44 46 62
	103	26 44 46 64
	104	26 44 46 66
	105	26 44 62 64
	106	26 44 62 66
	107	26 44 64 66
	108	26 46 62 64
	109	26 46 62 66
	110	26 46 64 66
	111	26 62 64 66
	112	42 44 46 62
	113	42 44 46 64
	114	42 44 46 66
	115	42 44 62 64
	116	42 44 62 66
	117	42 44 64 66
	118	42 46 62 64
	119	42 46 62 66
	120	42 46 64 66
	121	42 62 64 66
	122	44 46 62 64
	123	44 46 62 66
	124	44 46 64 66
	125	44 62 64 66
	126	46 62 64 66

Results

FIG. 61 illustrates the fluorescence signals produced by binding of cholera toxin to the microarray of candidate artificial receptors alone and in competition with each of the three concentrations of GM1. The magnitude of the fluorescence signal decreases steadily with increasing concentration of GM1. The amount of decrease is not quantitatively identical for all of the receptors, but each receptor experienced decreased binding of cholera toxin. These decreases indicate that GM1 competed with the artificial receptor for binding to the cholera toxin.
The decreases show a pattern of relative competition for the binding site on cholera toxin. This can be demonstrated through graphs of fluorescence signal obtained at a particular concentration of GM1 against fluorescence signal in the absence of GM1 (not shown). Certain of the receptors appear at similar relative positions on these plots as concentration of GM1 increases.
The disruption in cholera toxin binding caused by GM1 can be visualized as the ratio of the amount bound in the absence of GM1 OS to the amount bound upon competition with GM1. This ratio is illustrated in FIG. 62. The larger the ratio, the more cholera toxin remained bound to the artificial receptor upon competition with GM1. The ratio can be as large as about 14. The ratios are independent of the quantity bound in the control.
Interestingly, in several instances minor changes in structure to the artificial receptor caused significant changes in the ratio. For example, the artificial receptor including building blocks 24, 26, 46, and 66 differs from that including 24, 42, 46, and 66 by only substitution of a single building block. (xy indicates building block TyrAxBy.) The substitution of building block 42 for 26 increased binding in the presence of GM1 by about 14-fold.
By way of further example, the artificial receptor including building blocks 22, 24, 46, and 64 differs from that including 22, 46, 62, and 64 by only substitution of a single building block. The substitution of building block 24 for 62 increased binding in the presence of GM1 by about 3-fold.
Even substitution of a single recognition element affected binding. The artificial receptor including building blocks 22, 24, 42, and 44 differs from that including 22, 24, 42, and 46 by only substitution of a single recognition element. The substitution of building block 44 for 46 (a change of recognition element B6 to B4) increased binding in the presence of GM1 by about 3-fold.

Conclusions

This experiment demonstrated that binding of a test ligand to an artificial receptor of the present invention can be diminished (e.g., competed) by a candidate disruptor molecule. In this case the test ligand was the protein cholera toxin and the candidate disruptor was a compound known to bind to cholera toxin, GM1. Minor changes in structure of the building blocks making up the artificial receptor caused significant changes in the competition.

Example 6

GM1 Employed as a Building Block Alters Binding of Cholera Toxin to the Present Artificial Receptors

Microarrays of candidate artificial receptors were made, GM1 was bound to the arrays, and they were evaluated for binding of cholera toxin. The results obtained demonstrate that adding GM1 as a building block in an array of artificial receptors can increase binding to certain of the receptors.

Materials and Methods

Building blocks were synthesized and activated as described in Example 1. The building blocks employed in this example were those described in Example 4. Microarrays for the evaluation of the 171 n=2 candidate receptor environments were prepared as described above for Example 4. The test ligand employed in these experiments was cholera toxin labeled with the Alexa™ fluorophore (Molecular Probes Inc., Eugene, Oreg.). Cholera toxin was employed at 0.01 ug/ml (0.17 pM) or 0.1 ug/ml (1.7 pM) in both the control and the competition experiments. GM1 was employed as a test ligand for the artificial receptors and became a building block for receptors used to bind cholera toxin. The arrays were contacted with GM1 at either 100 μg/ml, 10 μg/ml, or 1 μg/ml as described above for cholera toxin and then rinsed with deionized water. The arrays were then contacted with cholera toxin under the conditions described above. Microarray analysis was conducted as described for Example 4. Table 2 identifies the building blocks in each receptor environment.

Results

FIG. 63 illustrates the fluorescence signals produced by binding of cholera toxin to the microarray of candidate artificial receptors without pretreatment with GM1. Binding of GM1 to the microarray of candidate artificial receptors followed by binding of cholera toxin produced fluorescence signals illustrated in FIGS. 64, 65, and 66 (100 μg/ml, 10 μg/ml, and 1 μg/ml GM1, respectively).
The enhancement of cholera toxin binding caused by pretreatment with GM1 can be visualized as the ratio of the amount bound in the presence of GM1 to the amount bound in the absence of GM1. This ratio is illustrated in FIG. 67 for 1 μg/ml GM1. The larger the ratio, the more cholera toxin bound to the artificial receptor after pretreatment with GM1. The ratio can be as large as about 16.
In several instances minor changes in structure to the artificial receptor caused significant changes in the ratio. For example, the artificial receptor including building blocks 46 and 48 differs from that including 46 and 88 by only substitution of a single recognition element on a single building block. (xy indicates building block TyrAxBy.) The substitution of building block 48 for 88 (a change of recognition element A8 to A4) increased the ratio representing increased binding the presence of GM1 building block from about 0.5 to about 16. Similarly, the artificial receptor including building blocks 42 and 77 differs from that including 24 and 77 by only substitution of a single building block. The substitution of building block 42 for 24 increased the ratio representing increased binding the presence of GM1 building block from about 2 to about 14.
Interestingly, several building blocks that exhibited high levels of binding of cholera toxin (signals of 45,000 to 65,000 fluorescence units) and that include the building block 33 were not strongly affected by the presence of GM1 as a building block.

Conclusions

This experiment demonstrated that binding of GM1 to an artificial receptor of the present invention can significantly increase binding by cholera toxin. Minor changes in structure of the building blocks making up the artificial receptor caused significant changes in the degree to which GM1 enhanced binding of cholera toxin.

Discussion of Examples 4-6

We have previously demonstrated that an array of working artificial receptors bind to a protein target in a manner which is complementary to the specific environment presented by each region of the proteins surface topology. Thus the pattern of binding of a protein target to an array of working artificial receptors describes the proteins surface topology; including surface structures which participate in e.g., protein˜small molecule, protein˜peptide, protein-protein, protein˜carbohydrate, protein˜DNA, etc. interactions. It is thus possible to use the binding of a selected protein to a working artificial receptor array to characterize these protein˜small molecule, protein˜peptide, protein-protein, protein˜carbohydrate, protein˜DNA, etc. interactions. Moreover, it is possible to utilize the protein to array interactions to define “leads” for the disruption of these interactions.
Cholera Toxin B sub-unit binds to GM1 on the cell surface (structure of GM1). Studies to identify competitors to this binding event have shown that competitors to the cholera toxin: GM1 binding interaction (binding site) can utilize both a sugar and an alkyl/aromatic functionality (Pickens, et al., Chemistry and Biology, vol. 9, pp 215-224 (2002)). We have previously demonstrated that fluorescently labeled Cholera Toxin B sub-unit binds to arrays of working artificial receptors to give a defined binding pattern which (vida infra) reflects cholera toxin B's surface topology. For this study, we sought to demonstrate that the binding of the cholera toxin to at least some members of the array could be disrupted using cholera toxins natural ligand, GM1.
The results presented in the figures clearly demonstrate that these goals have been achieved. Specifically, competition between the GM1 OS pentasaccharide or GM1 and a working artificial receptor array for cholera binding clearly gave a binding pattern which was distinct from the cholera binding pattern control. Moreover, these results demonstrated the complementarity between several of the working artificial receptors which contained a naphthyl moiety when compared to working artificial receptors which only contained phenyl functionality. These results are in keeping with the active site competition studies in Pickens, et al. and indicate that the naphthyl and phenyl derivatives represent good mimics/probes for the cholera to GM1 interaction. The specificity of these interactions was particularly demonstrated by the observation that the change of a single building block out of 4 in a combination of 4 building blocks system changed a non-competitive to a significantly competitive environment. These results also indicated that selected working artificial receptors can be used to develop a high-throughput screen for the further evaluation of the cholera: GM1 interaction.
Additionally, we sought to demonstrate that an affinity support/membrane mimic could be prepared by pre-incubating an array of artificial receptors with GM1 which would then bind/capture cholera toxin in a binding pattern which could be used to select a working artificial receptor(s) for, for example, the high-throughput screen of lead compounds which will disrupt the “cholera: membrane˜GM1 mimic”. The GM1 pre-incubation studies clearly demonstrated that several of the working artificial receptors which were poor cholera binders significantly increased their cholera binding, presumably through an affinity interaction between the cholera toxin and BOTH the immobilized GM1 pentasaccharide moiety and the working artificial receptor building block environment.
It should be noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a composition containing “a compound” includes a mixture of two or more compounds. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
It should also be noted that, as used in this specification and the appended claims, the phrase “adapted and configured” describes a system, apparatus, or other structure that is constructed or configured to perform a particular task or adopt a particular configuration. The phrase “adapted and configured” can be used interchangeably with other similar phrases such as arranged and configured, constructed and arranged, adapted, constructed, manufactured and arranged, and the like.
All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this invention pertains. All of the U.S. patents and published U.S. patent applications referenced in this application are incorporated by reference as if fully reproduced herein.
The invention has been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention.

Claims

1. An electrochemical sensing system comprising:

a working electrode;

a reference electrode; and

a working artificial receptor that is coupled to the working electrode, wherein the sensing system is configured to generate a sensing signal.

2. The electrochemical sensing system of claim 1 further comprising a membrane between the working electrode and the reference electrode, the working artificial receptor being coupled to the membrane.

3. The electrochemical sensing system of claim 1 wherein the system is configured to detect a chemical reaction by detecting a flow of electrons between the working electrode and the reference electrode.

4. The electrochemical sensing system of claim 1 wherein the system is configured to detect a chemical reaction by detecting a potential difference between the reference electrode and the working electrode.

5. The electrochemical sensing system of claim 1 comprising an array of working electrodes.

6. The electrochemical sensing system of claim 1 wherein the working receptors are coupled to a carbon paste that is electrically coupled to the working electrode.

7. The sensing system of claim 1, wherein the system is configured to detect at least one of: pathogenic microorganism, cancerous cell, pollutant in water, airborne pollutant, explosive-related vapor, protein, polynucleotide.

8. An electrochemical sensing system comprising:

a field effect transistor;

a working artificial receptor that is coupled to the field effect transistor, wherein a signal can be generated when a test ligand binds to a working artificial receptor.

9. The electrochemical sensing system of claim 8 wherein the field effect transistor is one of: a ChemFET, an ISFET, a SAFET, an SGFET.

10. The electrochemical sensing system of claim 8 wherein the working artificial receptor is coupled to a gate.

11. The electrochemical sensing system of claim 8 wherein the working artificial receptor is coupled to an insulating layer.