Biosensor electrode mediators for regeneration of cofactors

• US 8,221,612 B2
• Filed: 09/30/2008
• Issued: 07/17/2012
• Est. Priority Date: 10/16/1997
• Status: Expired due to Fees

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Inventors: Forrow, Nigel J., Sanghera, Gurdial S., Watkin, Jared L., Walters, Stephan
• Primary Examiner(s): Olsen, Kaj K
• Application Number:
  US12/242,760
• Publication Number:
  US 20090090625A1
• Time in Patent Office: 1,386 Days
• Field of Search: 204/403.01, 204/403.02, 204/403.12, 204/403.14, 205/777.5
• US Class Current: 205/777.5
• 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 method of determining concentration of glucose in a sample, the method comprising:

applying the sample to a biosensor, wherein the biosensor comprises;

a first and a second substrate comprising a reaction zone therebetween;

a plurality of electrodes comprising a fill indicator electrode, a working electrode, and a counter or counter/reference electrode formed on the first substrate, wherein the reaction zone comprises an enzyme, a cofactor, and a mediator associated with at least the working electrode, wherein the mediator consists of one of the two following formulae;

2. The method according to claim 1, wherein the method comprises applying the potential between the working electrode and the reference/counter electrode as soon as the sample covers the plurality of electrodes.

3. The method according to claim 1, wherein the method comprises applying a potential that is 200 mV or less.

4. The method according to claim 1, wherein determining the concentration of glucose in the sample comprises measuring the current between the working electrode and the reference/counter electrode for about 5 to 60 seconds.

5. The method according to claim 4, wherein measuring the current between the working electrode and the counter/reference electrode comprises measuring a signal that increases linearly with the concentration of glucose in the sample.

6. The method according to claim 1, wherein the cofactor comprises NAD.

7. The method according to claim 1, wherein the enzyme comprises glucose dehydrogenase.

8. The method according to claim 1, wherein the mediator comprises nickel phenanthroline quinone.

9. The method according to claim 1, wherein at least a portion of the plurality of electrodes are positioned in the reaction zone.

10. The method according to claim 1, further comprising a third substrate, wherein the third substrate is a spacer positioned between the first and the second substrates.