Test strip

• US 5,912,139 A
• Filed: 07/21/1997
• Issued: 06/15/1999
• Est. Priority Date: 07/23/1996
• Status: Expired due to Fees

• Current Assignee: Unitika Limited
• Original Assignee: Unitika Limited
• Inventors: Nakajima, Hiroshi, Iwata, Ken, Kawahara, Kazue
• Primary Examiner(s): Leary, Louise N.
• Application Number:
  US08/897,626
• Time in Patent Office: 694 Days
• Field of Search: 435/26, 435/14, 435/11, 435/21, 435/970, 435/975
• US Class Current: 435/26
• CPC Class Codes: C12Q 1/32 involving dehydrogenase
• CPC Class Codes: Y10S 435/97 Test strip or test slide
• CPC Class Codes: Y10S 435/975 Kit

Abstract

A test strip which comprises a carrier, a dehydrogenase, diaphorase, a fluorescent chromogen, and NAD or NADP. The test strip provides high sensitivity and high accuracy measurement, and have excellent storage stability.

Claims

1. A test strip which comprises a carrier, a dehydrogenase, diaphorase, a fluorescent chromogen, and NAD or NADP.

2. The test strip of claim 1 for measuring a substance, wherein the substance to be measured is a substrate of the dehydrogenase.

3. The test strip of claim 1 for measuring a substance, further comprising one or more enzymes which convert the substance to be measured into a substance which is a substrate of the dehydrogenase.

4. The test strip of claim 1 for measuring a substance selected from the group consisting of glucose 6-phosphate, glycerophosphoric acid, glycerol, phenylalanine, leucine, alanine, androsterone, cholesterol and fucose, and the dehydrogenase is specific for catalyzing the removal and transfer of hydrogen from the substance to be measured or from a product derived from the substance to be measured.

5. The test strip of claim 1, wherein the fluorescent chromogen is selected from the group consisting of resazulin and alamar blue.

6. The test strip of claim 1, impregnated with (i) a diaphorase solution having an activity of from 0.1 to 1,000,000 units per liter in an amount of from 1 to 1,000 μ

l per 100 cm² of the test strip; and

(ii) a dehydrogenase solution having an activity of from 0.1 to 1,000,000 units per liter in an amount of from 1 to 1,000 μ

l per 100 cm² of the test strip.

7. The test strip of claim 1, impregnated with a NAD or NADP solution having a concentration of from 0.001 to 200 mM in an amount of from 0.1 to 10,000 μ

l per 100 cm² of the test strip.

8. The test strip of claim 1, wherein in the carrier is selected from the group consisting of paper, non-woven fabric and a membrane filter.

9. The test strip of claim 1 for measuring glycerol, wherein the dehydrogenase comprises glycerol dehydrogenase and the fluorescent chromogen comprises resazulin.

10. The test strip of claim 1 for measuring phenylalanine, wherein the dehydrogenase comprises phenylalanine dehydrogenase and the fluorescent chromogen comprises alamar blue.

11. The test strip of claim 1 for measuring cholesterol, wherein the dehydrogenase comprises cholesterol dehydrogenase and the fluorescent chromogen comprises alamar blue.

12. The test strip of claim 1 for measuring galactose, wherein the dehydrogenase comprises galactose dehydrogenase and the fluorescent chromogen comprises resazulin.

13. The test strip of claim 1 for measuring fucose, wherein the dehydrogenase comprises fucose dehydrogenase and the fluorescent chromogen comprises resazulin.

14. The test strip of claim 1 for measuring alanine, wherein the dehydrogenase comprises alanine dehydrogenase and the fluorescent chromogen comprises resazulin.

15. The test strip of claim 1 for measuring leucine, wherein the dehydrogenase comprises leucine dehydrogenase and the fluorescent chromogen comprises resazulin.

16. The test strip of claim 1 for measuring glucose, further comprising ATP and hexokinase wherein, the dehydrogenase comprises glucose 6-phosphate dehydrogenase and the fluorescent chromogen comprises resazulin.

17. The test strip of claim 1, further comprising one or more of a buffer, an activating agent, a stabilizing agent and a viscosity-improving agent.

18. A test kit comprising a test strip disposed on a substrate, wherein the test strip comprises a carrier, a dehydrogenase, diaphorase, a fluorescent chromogen, and NAD or NADP.

19. The test kit of claim 18, wherein the substrate is selected from the group consisting of polystyrene film, polyethylene terephthalate film and paper board.

20. A method for measuring the concentration of a substance in a sample, said method comprising the steps of:

(1) spotting a predetermined amount of a sample containing a substance on the test strip, said test strip comprising a carrier, a dehydrogenase, diaphorase, a fluorescent chromogen, and NAD or NADP,

(2) after sufficient soaking of the sample in the test strip, the fluorescence strength of the reduced fluorescent chromogen is measured by irradiating the test strip with a light source of a specified wavelength,

(3) the difference between the blank value and the fluorescence strength is determined, and

(4) the concentration of the substance in the sample is calculated using a calibration curve.