Diagnostics based on tetrazolium compounds

• US 6,656,697 B1
• Filed: 02/25/2000
• Issued: 12/02/2003
• Est. Priority Date: 09/28/1998
• Status: Expired due to Term

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Ouyang, Tianmei, Yu, Yeung Siu
• Primary Examiner(s): Chin, Christopher L.
• Assistant Examiner(s): Do, Pensee T.
• Application Number:
  US09/513,071
• Time in Patent Office: 1,376 Days
• Field of Search: 435/25, 435/14, 435/287.7, 435/287.8, 435/962, 435/970, 435/7.9, 436/110, 436/537, 422/56, 422/57
• US Class Current: 435/7.9
• CPC Class Codes: C12Q 1/26 involving oxidoreductase
• CPC Class Codes: C12Q 1/32 involving dehydrogenase
• CPC Class Codes: C12Q 1/54 involving glucose or galactose
• CPC Class Codes: G01N 33/525 Multi-layer analytical elements
• CPC Class Codes: G01N 33/64 involving ketones
• CPC Class Codes: Y10S 435/962 Prevention or removal of interfering materials or reactants or other treatment to enhance results, e.g. determining or preventing nonspecific binding
• CPC Class Codes: Y10S 435/97 Test strip or test slide
• CPC Class Codes: Y10T 436/173076 Nitrite or nitrate

Abstract

A reagent is suitable for measuring the concentration of an analyte in a hemoglobin-containing biological fluid, such as whole blood. The reagent comprises a flavin-dependent enzyme that has specificity for the analyte, a flavin cofactor if, and only if, a flavin is not bound to the enzyme, a tetrazolium dye precursor, an electron transfer agent, and a nitrite salt. The reagent causes dye formation that is a measure of the analyte concentration. The nitrite salt suppresses interfering dye formation caused non-enzymatically by the hemoglobin. Preferably, the reagent is used in a dry strip for measuring glucose in whole blood.

Claims

1. A dry reagent strip for measuring a concentration of an analyte in a hemoglobin-containing biological fluid comprising a support layer on which is a test pad having a coating of a reagent comprising:

a) a flavin-dependent enzyme that has a flavin bound to it and that has specificity for the analyte,

b) a tetrazolium dye precurser,

c) an electron transfer agent, and

d) a nitrite salt.

2. The strip of claim 1 in which the test pad has a positively-charged surface.

3. The strip of claim 1 in which the test pad comprises a polyamide.

4. The strip of claim 1 further comprising a bibulous top layer overlaying the test pad.

5. A dry reagent strip for measuring a concentration of an analyte in a hemoglobin-containing biological fluid comprising a support layer on which is a test pad having a coating of a reagent comprising:

a) a flavin-dependent enzyme that has a flavin bound to it and that has specificity for the analyte,

b) flavin mononucleotide (FMN) or flavin adenine dinucleotide (FAD),

c) a tetrazolium dye precurser,

d) an electron transfer agent, and

e) a nitrite salt.

6. A dry reagent strip for measuring a concentration of an analyte in a hemoglobin-containing biological fluid comprising a support layer on which is a test pad and a top layer overlaying the test pad in which the test pad is coated in a reagent comprising:

a) a flavin-dependent enzyme that has a flavin bound to it and that has specificity for the analyte,

b) a tetrazolium dye precurser, and

c) an electron transfer agent;

and the support layer and/or the top layer is coated with a nitrite salt.

7. The strip of claim 6 in which the top layer is bibulous.

8. The strip of claim 6 further comprising a channeled spacer spacer and channel between the top layer and test pad to provide a capillary path between the top layer and pad.

9. The strip of claim 6 in which the analyte is glucose and the enzyme is glucose oxidase.

10. The strip of claim 6 in which the tetrazolium dye precursor is 2,2′

-dibenzothiazolyl-5,5′

-bis[4-di(2-sulfoethyl)carbamoylphenyl]-3,3-(3,3-dimethoxy-4,4′

-biphenylene)ditetrazolium, disodium salt (WST-5).

11. A dry reagent strip for measuring a concentration of an analyte in a hemoglobin-containing biological fluid comprising a support layer on which is a test pad and a top layer overlaying the test pad in which the test pad is coated in a reagent comprising:

a) a flavin-dependent enzyme that has a flavin bound to it and that has specificity for the analyte,

b) flavin mononucleotide (FMN) or flavin adenine dinucleotide (FAD),

c) a tetrazolium dye precurser, and

d) an electron transfer agent;

and the support layer and/or the top layer is coated with a nitrite salt.

12. A dry reagent test strip for measuring a concentration of glucose in a hemoglobin-containing biological fluid, comprising:

a) a support layer

b) on the support layer, a test pad having a coating that comprises

i) glucose oxidase that has a flavin bound to it,

ii) a tetrazolium dye precurser, and

iii) phenazine methosulfate (PMS) or an analog thereof, and

c) on the test pad, a bilubous top layer that is coated with a nitrite salt.

13. A dry reagent test strip for measuring a concentration of glucose in a hemoglobin-containing biological fluid, comprising

a) a support layer

b) on the support layer, a test pad having a coating that comprises:

a. a flavin-dependent enzyme that does not have a flavin bound to it,

b. flavin mononucleotide (FMN) or flavin adenine dinucleotide (FAD),

c. a tetrazolium dye precurser, and

d. phenazine methosulfate (PMS) or an analog thereof, and

c) on the test pad, a bilubous top layer that is coated with a nitrite salt.