METHODS FOR GENERATING pH/IONIC CONCENTRATION GRADIENT NEAR ELECTRODE SURFACES FOR MODULATING BIOMOLECULAR INTERACTIONS

• US 20140008244A1
• Filed: 07/06/2012
• Published: 01/09/2014
• Est. Priority Date: 07/06/2012
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Sam Kavusi
• Inventors: Lau, Aldrich N. K., KAVUSI, Sam, Gangadharan, Rajan, Johnson, Christopher, Verma, Piyush
• Granted Patent: US 9,075,041 B2
• Time in Patent Office: Days
• US Class Current: 205/777.5
• CPC Class Codes: G01N 27/3275 Sensing specific biomolecules, e.g. nucleic acid strands, based on an electrode surface reaction
• CPC Class Codes: G01N 33/50 Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing measuring or testing processes involving enzymes or microorganisms, compositions or test papers therefor; processes for forming such compositions, condition responsive control in microbiological or enzymological processes C12Q
• CPC Class Codes: G01N 33/5306 Improving reaction conditions, e.g. reduction of non-specific binding, promotion of specific binding

Abstract

Methods of modulating the binding interactions between a (biomolecular) probe or detection agent and an analyte of interest from a biological sample in a biosensor having a multisite array of test sites. In particular, the methods modulate the pH or ionic concentration gradient near the electrodes in such biosensor. The methods of modulating the binding interactions provide a biosensor and analytic methods for more accurately measuring an analyte of interest in a biological sample.

Claims

1. A method of modulating the pH or ionic concentration in a biosensor, the method comprising:

a) providing a biosensor comprising a multisite array of test sites in which the conditions for interacting with a biomolecule analyte can be varied independently, each test site comprising a support in an aqueous solution, the support comprising one or more electrodes or an electromagnet, and a biomolecule interface layer having one or more immobilized probes thereon;

b) adding an electrochemically active agent, an enzyme, an enzyme substrate, a buffer inhibitor, or a combination thereof to the aqueous solution; and

c) reacting the electrochemically active agent, the enzyme, the enzyme substrate, or combination thereof in the aqueous solution to produce H⁺ ion or OH⁻

ions, or increasing the diffusion of H⁺ ions or OH⁻

ions with the buffer inhibitor, or inhibiting the interaction between H⁺ ions or OH⁻

ions and buffering salts with the buffer inhibitor.

2. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the aqueous solution comprises a water-miscible organic co-solvent selected from the groups consisting of acetonitrile, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), N,N-dimethyl acetamide (DMAc), and mixtures thereof.

3. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the biomolecular interface layer having one or more immobilized probes thereon comprises a layer of immobilized polymers and the probes.

4. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the biomolecular interface layer comprises a silane immobilized polyethylene glycol (PEG), wherein at least a portion of the surface-immobilized PEG comprises terminal functional groups selected from the group consisting N-hydroxysuccinimide (NHS) ester, maleimide, alkynes, azides, streptavidin and biotin.

5. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein in step b) an electrochemically active agent is added to the aqueous solution, and in step c) the electrochemically active agent is oxidized or reduced.

6. The method of modulating the pH or ionic concentration in a biosensor according to claim 5, wherein the electrode potential is in the range of −

1V to +1V vs Ag/AgCl.

7. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the electrochemically active agent is added at a concentration of 1 nM to 100 mM.

8. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the electrochemically active agent is selected from the group consisting of dopamine hydrochloride, ascorbic acid, phenol and derivatives thereof, benzoquinones and derivatives thereof, naphthoquinones and derivatives thereof, and 9,10-anthraquinone and derivatives thereof.

9. The method of modulating the pH or ionic concentration in a biosensor according to claim 5, further comprising adding a buffer inhibitor to the aqueous solution.

10. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the biosensor comprises a support in an aqueous solution, the support comprising one or more electrodes, and a biomolecule interface layer having one or more immobilized probes and one or more immobilized enzymes, in step b) an enzyme substrate is added to the aqueous solution, and in step c) the enzyme substrate is enzymatically oxidized or reduced.

11. The method of modulating the pH or ionic concentration in a biosensor according to claim 10, wherein the immobilized enzyme is an oxidase, urease, or dehydrogenase.

12. The method of modulating the pH or ionic concentration in a biosensor according to claim 10, further comprising adding a buffer inhibitor to the aqueous solution.

13. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the support comprises an electromagnet and the biomolecule interface layer has one or more immobilized probes, in step b) one or more enzymes immobilized onto magnetic micro- or nano-particles are added prior to or simultaneously with an enzyme substrate, and in step c) the enzyme substrate is enzymatically oxidized or reduced.

14. The method of modulating the pH or ionic concentration in a biosensor according to claim 13, wherein the immobilized enzyme is an oxidase, urease, or dehydrogenase.

15. The method of modulating the pH or ionic concentration in a biosensor according to claim 13, further comprising adding a buffer inhibitor to the aqueous solution.

16. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein in step b) an enzyme is added to the aqueous solution, and in step c) the enzyme is reacted at the electrode surface.

17. The method of modulating the pH or ionic concentration in a biosensor according to claim 16, further comprising adding a buffer inhibitor to the aqueous solution.

18. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein in step b) a buffer inhibitor is added to the aqueous solution, and in step c) the diffusion of H⁺ ions or OH⁻

ions is facilitated or the interaction between H⁺ ions or OH⁻

ions and buffering salts is inhibited.

19. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the buffer inhibitor is a soluble polymer selected from poly(allylamine hydrochloride), poly(diallyldimethyl ammonium chloride), poly(vinylpyrroldone), poly(ethyleneimine), poly(vinylamine), poly(4-vinylpyridine) and tris(2-carboxyethyl)phosphine hydrochloride

20. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the biosensor comprises a CMOS, electrode array, or TFT based system.

21. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the electrode is an indium tin oxide, gold or silver electrode.

22. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the support is a glass or plastic support.

23. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the immobilized probe is selected from a protein, a peptide, a nucleic acid and a cell.

24. The method of modulating the pH or ionic concentration in a biosensor according to claim 21, wherein the protein is an antibody.

25. The method of modulating the pH or ionic concentration in a biosensor according to claim 1, wherein the biomolecule interface layer is covering the one or more electrodes and has a thickness of 5-150 nm.

26. A biosensor for use in detecting a biomolecule analyte comprising a multisite array of test sites in which the conditions for interacting with the biomolecule analyte can be varied independently, each test site comprising:

a) a support in an aqueous environment;

b) one or more electrodes; and

c) a biomolecule interface layer having one or more immobilized detection agents and one or more immobilized enzymes.

27. The biosensor according to claim 26, wherein the support comprises an electromagnet.

28. The biosensor according to claim 26, wherein the biosensor comprises a CMOS, electrode array, or TFT based system.

29. The biosensor according to claim 26, wherein the electrode is an indium tin oxide, gold or silver electrode.

30. The biosensor according to claim 26, wherein the support is a glass or plastic support.

31. The biosensor according to claim 26, wherein the immobilized detection agent is selected from a protein, a peptide, a nucleic acid and a cell.

32. A method for detecting a biomolecule analyte in a biological sample, the method comprising:

a) providing a biosensor comprising a multisite array of test sites in which the conditions for interacting with a biomolecule analyte can be varied independently, each test site comprising a support in an aqueous solution, the support comprising one or more electrodes or an electromagnet, and a biomolecule interface layer having one or more immobilized probes thereon;

b) adding in each test site an electrochemically active agent, an enzyme, an enzyme substrate, a buffer inhibitor, or a combination thereof to the aqueous solution;

c) reacting the electrochemically active agent, the enzyme, the enzyme substrate, or a combination thereof in the aqueous solution to produce H⁺ ion or OH⁻

ions, or increasing the diffusion of H⁺ ions or OH⁻

ions with a buffer inhibitor, or inhibiting the interaction between H⁺ ions or OH⁻

ions and buffering salts with the buffer inhibitor;

d) adding a biological sample to each test site; and

e) detecting the biomolecule analyte in each test site,

wherein the amounts added in step b) and the reaction in step c) are varied between test sites in a subset array of test sites in order to obtain sets of test sites in which the pH or ionic concentration near electrode surfaces in the test sites varies.

33. The method for detecting a biomolecule analyte in a biological sample according to claim 32, wherein amount of biological sample or the concentration of the biological sample is varied between subset arrays of test sites.

34. The method for detecting a biomolecule analyte in a biological sample according to claim 32, wherein the aqueous solution comprises a water-miscible organic co-solvent selected from the groups consisting of acetonitrile, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), N,N-dimethyl acetamide (DMAc), and mixtures thereof.