Mediator stabilized reagent compositions and methods for their use in electrochemical analyte detection assays

• US 20040050717A1
• Filed: 09/12/2002
• Published: 03/18/2004
• Est. Priority Date: 09/12/2002
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Hodges, Alastair McIndoe, Chatelier, Ronald C., Teodorczyk, Maria, Ohara, Timothy J., Dato, Remy
• Granted Patent: US 7,291,256 B2
• Time in Patent Office: Days
• 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

Abstract

Mediator stabilized reagent compositions and methods for their use in electrochemical analyte determination assays are provided. The subject reagent compositions include an enzyme, a redox mediator and a mediator-stabilizing buffer. Optionally, the reagent compositions may further include one or more of a wetting agent, detergent, enzyme cofactor and combinations thereof. Also provided are electrochemical test strips that include the subject reagent compositions, systems and kits that include the same as well as methods for using the same in analyte detection assays. The subject invention finds use in a variety of different applications, including glucose concentration determination applications.

Claims

1. A reagent composition comprising:

(a) an enzyme;

(b) a redox mediator; and

(c) a mediator-stabilizing buffer present in an amount sufficient to storage stabilize said redox mediator.

2. The reagent composition according to claim 1, wherein said buffer has a pKa ranging from about 5 to about 8.

3. The reagent composition according to claim 2, wherein said buffer has a pKa ranging from about 6 to about 7.

4. The reagent composition according to claim 1, wherein said buffer is formulated to have a pH in the range from about 4 to 8.

5. The reagent composition according to claim 4, wherein said buffer is formulated to have a pH in the range from about 6 to 7.

6. The reagent composition according to claim 1, wherein said buffer has a low binding affinity of divalent metal ions.

7. The reagent composition according to claim 1, wherein said buffer comprises a polycarboxylic acid.

8. The reagent composition according to claim 7, wherein said polycarboxylic acid has at least two carboxylic acid groups.

9. The reagent composition according to claim 7, wherein said at least two carboxylic acid groups are present in a cis formation.

10. The reagent composition according to claim 9, wherein said at least two carboxylic groups present in a cis formation are bonded to an ethylene moiety.

11. The reagent composition according to claim 10, wherein said polycarboxylic acid is mellitic acid and salts thereof.

12. The reagent composition according to claim 10, wherein said polycarboxylic acid is citraconic acid and salts thereof.

13. The reagent composition according to claim 1, wherein said composition is a liquid.

14. The reagent composition according to claim 13, wherein said buffer is present in said liquid composition at a concentration ranging from about 0.5 to about 500 mM.

15. The reagent composition according to claim 14, wherein said buffer is present in said liquid composition at a concentration ranging from about 0.5 to about 100 mM.

16. The reagent composition according to claim 13, wherein said buffer is present in said liquid composition at a concentration ranging from about 50 to about 300 mM.

17. The reagent composition according to claim 1, wherein said composition is a dry composition.

18. The reagent composition according to claim 17, wherein said buffer is present in said dry composition in an amount ranging from about 0.01 to about 40% wt/wt.

19. The reagent composition according to claim 1, wherein said enzyme is an oxidizing enzyme.

20. The reagent composition according to claim 19, wherein said oxidizing enzyme is chosen from an oxidase and a dehydrogenase.

21. The reagent composition according to claim 19, wherein said enzyme is a dehydrogenase.

22. The reagent composition according to claim 19, wherein said oxidizing enzyme is a glucose oxidizing enzyme.

23. The reagent composition according to claim 1, wherein said reagent composition further comprises an enzyme cofactor.

24. The reagent composition according to claim 1, wherein said mediator is ferricyanide.

25. The reagent composition according to claim 1, wherein said reagent composition further comprises a stabilizer.

26. The reagent composition according to claim 25, wherein said stabilizer is a carbohydrate.

27. The reagent composition according to claim 26, wherein said carbohydrate is sucrose.

28. An electrochemical cell comprising a reagent composition according to claim 1.

29. The electrochemical cell according to claim 28, wherein said cell is present in an electrochemical test strip.

30. In a method for making an electrochemical test strip, the improvement comprising:

employing a reagent composition according to claim 1.

31. A method for determining the concentration of an analyte in a sample, said method comprising:

(a) applying said sample to an electrochemical cell comprising a reagent composition according to claim 1;

(b) detecting an electrical signal produced by said cell; and

(c) relating said detected electrical signal to the concentration of said analyte in said sample.

32. A method according to claim 31, wherein said analyte is glucose.

33. A method according to claim 31, wherein said physiological sample is blood.

34. A kit for use in determining the concentration of an analyte in a physiological sample, said kit comprising:

(a) an electrochemical test strip according to claim 28;

and

(b) at least one of;

(i) a sample obtainment element; and

(ii) an analyte standard.

35. The kit according to claim 34, wherein said kit comprises said sample obtainment element.

36. The kit according to claim 34, wherein said sample obtainment element is a lance.

37. The kit according to claim 34, wherein said kit comprises said analyte standard.

38. A reagent system comprising:

(a) an electrochemical test strip according to claim 28;

and

(b) a meter for reading said test strip.