BIOSENSOR ELECTRODE MEDIATORS FOR REGENERATION OF COFACTORS

• US 20070289881A1
• Filed: 09/04/2007
• Published: 12/20/2007
• Est. Priority Date: 10/16/1997
• Status: Active Grant

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Laboratories Incorporated
• Inventors: Walters, Stephen, Watkin, Jared, Sanghera, Gurdial, Forrow, Nigel
• Granted Patent: US 8,012,341 B2
• Time in Patent Office: Days
• US Class Current: 205/777.500
• CPC Class Codes: C12Q 1/004 mediator-assisted
• CPC Class Codes: C12Q 1/005 involving specific analytes or enzymes including groups of enzymes, e.g. oxydases; C12Q1/004 takes precedence
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

The present invention is based on the discovery of NAD⁺ and NADP⁺ mediator compounds that do not bind irreversibly to thiol groups in the active sites of intracellular dehydrogenase enzymes. Such mediator compounds avoid a common mode of enzyme inhibition. The mediators can therefore increase the stability and reliability of the electrical response in amperometric electrodes constructed from NAD- or NADP-dependent enzymes.

Claims

1. A single use disposable electrode strip for attachment to the signal readout circuitry of a sensor system which measures ketone(s) in an aqueous sample, the strip comprising:

a) an elongated support having a substantially flat, planar surface, adapted for releasable attachment to the readout circuitry;

b) at least two conductors extending along the surface and comprising a first conductive element and a second conductive element for connection to the readout circuitry;

c) a plurality of electrodes, at least one active electrode on the surface in contact with the first conductive element, the active electrode comprising ketone specific enzymes and a counter/reference electrode contact with the second conductive element; and

d) said active electrode and the reference/counter electrode being configured so that a small drop of the aqueous sample provides an electrical conduction path between the electrodes.

2. The electrode strip of claim 1 wherein the enzyme(s) includes b-hydroxybutyrate dehydrogenase.

3. The electrode strip of claim 1 further comprising a mediator compound having one of the two following formulae:

where X and Y can independently be oxygen, sulphur, CR³R⁴, NR³, or NR³R⁴ or the functional group CZ¹Z², where Z¹ and Z² are electron withdrawing groups;

R₁ and R₂ can independently be a substituted or unsubstituted aromatic or heteroaromatic group; and

R³ and R⁴ can independently be a hydrogen atom, a hydroxyl group or a substituted or unsubstituted alkyl, aryl, heteroaryl, amino, alkoxyl, or aryloxyl group.

4. The electrode strip of claim 1, further including circuit loops for providing a resistance characteristic of the electrode strip to identify the strip as being suitable for a particular analyte.

5. The electrode strip of claim 1, further including at least one notch or other shape in an end of the strip to identify the strip as being suitable for a particular analyte.

6. The electrode strip of claim 1, further including at least one switch to identify the strip as being suitable for a particular analyte.

7. The electrode strip of claim 1, further including at least one optical indicator to identify the strip as being suitable for a particular analyte.

8. A process of measuring the concentration of ketones in an aqueous sample, comprising:

a) providing the electrode strip of claim 1 including at least one ketone detecting enzyme;

b) applying the sample including a ketone to the electrode strip;

c) detecting the sample applied to the electrode strip;

d) applying an electrical potential at an electrode and observing the resultant current; and

e) measuring the concentration of ketone from resultant current.

9. The process of claim 8 wherein the enzyme(s) includes b-hydroxybutyrate dehydrogenase.

10. The process of claim 8 further comprising a mediator compound having one of the two following formulae:

where X and Y can independently be oxygen, sulphur, CR³R⁴, NR³, or NR³R⁴ or the functional group CZ¹Z², where Z¹ and Z² are electron withdrawing groups;

R₁ and R₂ can independently be a substituted or unsubstituted aromatic or heteroaromatic group; and

R³ and R⁴ can independently be a hydrogen atom, a hydroxyl group or a substituted or unsubstituted alkyl, aryl, heteroaryl, amino, alkoxyl, or aryloxyl group.

11. The process of claim 8 wherein the current observed during the measurement period is linearly related to the concentration of the ketone(s) in the sample.

12. The process of claim 10 wherein the mediator is 1,10-phenanthroline quinone.

13. The process of claim 8 wherein the applied potential is 200 mV or less.

14. A single use disposable electrochemical strip for the measurement of ketone bodies in an aqueous sample, the strip comprising:

a) an electrode arrangement comprising a working electrode and a reference/counter electrode;

b) a reagent deposited on at least one of the electrodes, the reagent comprising at least one enzyme specific to ketone bodies and a mediator.

15. The electrode strip of claim 14 wherein the enzyme(s) includes b-hydroxybutyrate dehydrogenase.

16. The electrode strip of claim 14, further including at least one notch or other shape in an end of the strip to identify the strip as being suitable for a particular analyte.

17. The electrode strip of claim 14, further including at least one switch to identify the strip as being suitable for a particular analyte.

18. The electrode strip of claim 14, further including at least one optical indicator to identify the strip as being suitable for a particular analyte.