ELECTRODE, ELECTROCHEMICAL SENSOR AND APPARATUS, AND METHODS FOR OPERATING THE SAME

• US 20110213229A1
• Filed: 11/12/2009
• Published: 09/01/2011
• Est. Priority Date: 11/13/2008
• Status: Active Grant

• Current Assignee: Scottech Medical Company Limited
• Original Assignee: Mode Diagnostics Limited
• Inventors: Benoit, Vincent
• Granted Patent: US 9,170,265 B2
• Time in Patent Office: Days
• US Class Current: 600/345
• CPC Class Codes: G01N 27/3271 Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001
• CPC Class Codes: G01N 33/725 using peroxidative activity
• CPC Class Codes: G01N 33/726 Devices

Abstract

A method for amperometric detection of proteins, especially haemoglobin in faeces, using an electrochemical sensor. The electrochemical sensor includes: a working electrode having an electrically conductive matrix holding a first reagent and/or a second reagent, the second reagent being an oxidising agent, or a precursor thereof, for the first reagent; a counter electrode and optionally a reference electrode; wherein a reaction between the first reagent and the oxidising agent is catalysed by the protein to provide a detectable signal at the working electrode. The electrically conductive matrix is an electrically conductive carbon- or graphite-containing matrix or an electrically conductive porous matrix.

Claims

1. A method for detecting a protein, the method comprising the steps of:

(i) providing an electrochemical sensor, the electrochemical sensor comprising;

a working electrode having an electrically conductive matrix holding a first reagent and/or a second reagent, the second reagent being an oxidising agent or a precursor thereof for the first reagent;

a counter electrode and optionally a reference electrode;

wherein a reaction between the first reagent and the oxidising agent is catalysable by the protein to provide a detectable signal at the working electrode; and

the electrically conductive matrix is an electrically conductive carbon- or graphite containing matrix or an electrically conductive porous matrix;

(ii) making available the electrochemical sensor at an environment to be analysed for the protein;

(iii) making available for reaction the first reagent and the second reagent;

(iv) maintaining a potential across the working electrode and the counter electrode and/or the reference electrode, where present; and

(v) measuring the current passing between the working electrode and the counter and/or reference electrode where present.

2. The method according to claim 1, wherein the electrically conductive matrix is an electrically conductive carbon- or graphite-containing matrix.

3. The method according to claim 2, wherein the electrically conductive carbon- or graphite-containing matrix is a carbon paste.

4. The method according to claim 1, wherein the protein is haemoglobin.

5. The method according to claim 1, wherein the second reagent comprises hydrogen peroxide or a precursor thereof,

6. The method according to claim 5, wherein the second reagent is, or comprises, urea peroxide or sodium perborate.

7. The method according to claim 6, wherein the second reagent is sodium perborate.

8. The method according to claim 1, wherein the first reagent is, or comprises, a compound selected from tetramethylbenzidine, alpha guaiaconic acid, 2,2′

-azino bis(3-ethylbenzothiazolidine-6-sulphonic acid), hydroquinone, phenylenediamine, o-dianisidine, o-tolidine (dimethylbenzidine), 6-methoxyquinoline, and 3,3′

-diaminobenzidine, 3-amino-9-ethylcarbazole.

9. The method according to claim 8, wherein the first reagent is, or comprises, tetramethylbenzidine.

10. The method according to claim 1, the electrode further holding a wetting additive.

11. The method according to claim 10, wherein the wetting additive is selected from polyvinylpyrrolidone, Triton X, and tween.

12. The method according to claim 10, wherein the wetting additive is present in the electrically conductive matrix at 0.005-0.25 wt %.

13. The method according to claim 1, wherein the electrically conductive matrix is an electrically conductive carbon- or graphite-containing porous matrix.

14. The method according to claim 1, wherein the electrically conductive matrix holds the first reagent.

15. The method according to claim 14, wherein the first reagent is present in the electrically conductive matrix at 1-15 wt %.

16. The method according to claim 1, wherein the electrically conductive matrix holds the second reagent.

17. The method according to claim 16, wherein the second reagent is present in the electrically conductive matrix at 2-15 wt %.

18. The method according to claim 1, wherein the environment to be analysed is a biological sample from a subject.

19. The method according to claim 18, wherein the biological sample is a stool sample.

20. The method according to claim 18, wherein the biological sample is treated with a cell lysing agent.

21. The method according to claim 20, wherein the cell lysing agent is saponin.

22. The method according to claim 1, wherein the pH of the sample is at a pH of 4 to 5.

23. The method according to claim 18, wherein the subject is on a peroxidase-controlled diet.

24. A working electrode for use in the detection of a protein, the working electrode having an electrically conductive matrix holding a first reagent and a second reagent, the second reagent being an oxidizing agent or a precursor thereof for the first reagent;

wherein a reaction between the first reagent and the oxidizing agent is catalysable by the protein to provide a detectable signal at the working electrode; and

the electrically conductive matrix is an electrically conductive carbon- or graphite-containing matrix or an electrically conductive porous matrix.

25. An electrochemical sensor for use in the detection of a protein, wherein the electrochemical sensor comprises a working electrode having an electrically conductive matrix holding a first reagent and a second reagent, the second reagent being an oxidising agent or a precursor thereof for the first reagent;

wherein a reaction between the first reagent and the oxidising agent is catalysable by the protein to provide a detectable signal at the working electrode; and

the electrically conductive matrix is an electrically conductive carbon- or graphite-containing matrix or an electrically conductive porous matrix.

26. The electrochemical sensor according to claim 25 further comprising a voltage supply adapted to supply a constant bias between the working electrode and the counter electrode or the reference electrode, where present, a detector for monitoring current, and a controller for controlling the voltage supply and timing of that supply.

27. The electrochemical sensor according to claim 25 further comprising a second working electrode, wherein the second working electrode has an electrically conductive matrix holding a first reagent and/or a second reagent, the second reagent being an oxidising agent or a precursor thereof for the first reagent;

wherein a reaction between the first reagent and the oxidising agent is catalysable by the protein to provide a detectable signal at the working electrode; and

the electrically conductive matrix'"'"'is an electrically conductive carbon- or graphite-containing matrix or an electrically conductive porous matrix.

28. The electrochemical sensor according to claim 27, wherein the second working electrode is provided with means for reducing, or preventing in use, exposure of that second working electrode to the protein.

29. The electrochemical sensor according to claim 28, wherein the means is a membrane.

30. The electrochemical sensor according to claim 29, wherein the membrane has pores with an average cross-section of 5 mm or less.

31. A sensing apparatus comprising at least one electrochemical sensor, wherein the apparatus is adapted:

(i) for use with a sample from a subject;

(ii) to be swallowable, for passage through the human or animal body;

(iii) to be implantable in the human or animal body;

or

(iv) to be placed at a surface location of the human or animal body;

and the electrochemical sensor is for use in the detection of a protein, wherein the electrochemical sensor comprises a working electrode having an electrically conductive matrix holding a first reagent and a second reagent, the second reagent being an oxidising agent or a precursor thereof for the first reagent;

,

wherein a reaction between the first reagent and the oxidising agent is catalysable by the protein to provide a detectable signal at the working electrode; and

the electrically conductive matrix is an electrically conductive carbon- or graphite-containing matrix or an electrically conductive porous matrix.

32. A kit comprising a sensing apparatus adapted for use with a sample from a subject and further comprising a sampling apparatus for removal of a sample from a stool,

wherein the sensing apparatus comprising at least one electrochemical sensor and the electrochemical sensor is for use in the detection of a protein, wherein the electrochemical sensor comprises a working electrode having an electrically conductive matrix holding a first reagent and a second reagent, the second reagent being an oxidising agent or a precursor thereof for the first reagent;

wherein a reaction between the first reagent and the oxidising agent is catalysable by the protein to provide a detectable signal at the working electrode; and

the electrically conductive matrix is an electrically conductive carbon- or graphite-containing matrix or an electrically conductive porous matrix.

33. A method of preparing a working electrode, the method comprising the step of mixing an electrically conductive matrix with a first reagent and a second reagent thereby to provide a working electrode having an electrically conductive matrix holding a first reagent and a second reagent, the second reagent being an oxidising agent or a precursor thereof for the first reagent;

wherein a reaction between the first reagent and the oxidising agent is catalysable by the protein to provide a detectable signal at the working electrode; and

the electrically conductive matrix is an electrically conductive carbon- or graphite-containing matrix or an electrically conductive porous matrix.