Diagnostics based on tetrazolium compounds

• US 5,902,731 A
• Filed: 09/28/1998
• Issued: 05/11/1999
• 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): Fonda, Kathleen K.
• Assistant Examiner(s): Moran, Marjorie A.
• Application Number:
  US09/161,876
• Time in Patent Office: 225 Days
• Field of Search: 435/26, 435/14, 435/287.7, 435/287.8, 435/962, 435/970, 436/110
• US Class Current: 435/26
• CPC Class Codes: C12Q 1/32 involving dehydrogenase
• 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 dehydrogenase enzyme that has specificity for the analyte, NAD or an NAD derivative, a tetrazolium dye precursor, a diaphorase enzyme or an analog thereof, 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 ketone bodies, such as beta-hydroxybutyrate.

Claims

1. A reagent for measuring a concentration of an analyte in a hemoglobin-containing biological fluid, comprising

a) a dehydrogenase enzyme that has specificity for the analyte,

b) nicotinamide adenine dinucleotide (NAD) or an NAD derivative,

c) a tetrazolium dye precursor,

d) a diaphorase enzyme or an analog thereof, and

e) a nitrite salt.

2. The reagent of claim 1 in which the analyte is beta-hydroxybutyrate and the enzyme is beta-hydroxybutyrate dehydrogenase.

3. A dry reagent strip for determining the presence and amount of an analyte in a hemoglobin-containing biological fluid comprising a support layer on which is a test pad having a coating of the reagent of claim 1.

4. The strip of claim 3 further comprising a bibulous top layer overlaying the test pad.

5. A dry reagent strip for determining the presence and amount 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 a first part of the reagent of claim 1 is on the test pad and a second part of the reagent is on the support and/or top layer.

6. The strip of claim 5 in which the top layer is bibulous.

7. The strip of claim 5 further comprising a spacer and channel between the top layer and test pad to provide a capillary path between the top layer and pad.

8. The strip of claim 5 in which the analyte is beta-hydroxybutyrate and the enzyme is beta-hydroxybutyrate dehydrogenase.

9. The strip of claim 5 in which the analyte is glucose and the enzyme is glucose dehydrogenase.

10. The strip of claim 5 in which the analyte is glucose-6-phosphate and the enzyme is glucose-6-phosphate dehydrogenase.

11. The strip of claim 5 in which the analyte is alcohol and the enzyme is alcohol dehydrogenase.

12. The strip of claim 5 in which the analyte is L-lactate and the enzyme is L-lactate dehydrogenase.

13. The strip of claim 5 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).

14. A dry reagent test strip for determining the presence and amount of an analyte 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) a dehydrogenase enzyme that has specificity for the analyte,

ii) nicotinamide adenine dinucleotide (NAD) or an NAD derivative,

iii) a tetrazolium dye precursor, and

iv) a diaphorase enzyme or an analog thereof, and

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