Multi-enzymatic biosensors and stabilization of multi-enzymatic biosensors at room temperature

1. A biosensor comprising:

an electrode;

a plurality of enzymes immobilized over a surface of the electrode;

a diffusion barrier over the surface of the electrode; and

a polysaccharide;

wherein the diffusion barrier comprises a polymeric compound selected from the group consisting of poly(tetrafluoroethylene) ionomers, the perfluorosulfonate ionomer NAFION®, poly-(2-hydroxymethyl methacrylate), polyvinyl chloride, cellulose acetate, and mixtures and copolymers thereof.

2. The biosensor of claim 1 , wherein the electrode comprises platinum, gold, palladium, alloys of platinum, gold and palladium, or carbon.

3. The biosensor of claim 1 , wherein the electrode comprises graphite or carbon nanotube.

4. The biosensor of claim 1 , wherein said plurality of enzymes are cross-linked.

5. The biosensor of claim 1 , wherein the plurality of enzymes comprise creatinase, creatininase, or sarcosine oxidase, and wherein the diffusion barrier comprises a mixture containing polyurethane.

6. The biosensor of claim 1 , wherein the polysaccharide comprises sucrose, trehalose, raffinose, or lactitol.

7. The biosensor of claim 1 , wherein the biosensor is configured to measure creatine.

8. The biosensor of claim 1 , wherein the biosensor is configured to measure creatinine and creatine.

9. The biosensor of claim 1 , wherein the polysaccharide comprises 10% sucrose.

10. The biosensor of claim 1 , wherein the diffusion barrier is over both the surface of the electrode and the plurality of enzymes.

11. The biosensor of claim 1 , wherein the polysaccharide comprises a disaccharide.

12. A method of using a multi-enzyme biosensor, the multi-enzyme biosensor comprising:

an electrode;

a plurality of enzymes immobilized over a surface of the electrode;

a diffusion barrier over the surface of the electrode; and

a polysaccharide;

wherein the diffusion barrier comprises a polymeric compound selected from the group consisting of poly(tetrafluoroethylene) ionomers, the perfluorosulfonate ionomer NAFION®, poly-(2-hydroxymethyl methacrylate), polyvinyl chloride, cellulose acetate, and mixtures and copolymers thereof;

wherein the method comprises using the multi-enzyme biosensor to measure creatine, creatinine, or both creatine and creatinine in a body fluid sample.

13. The method of claim 12 , wherein the plurality of enzymes are cross-linked.

14. The method of claim 12 , wherein the plurality of enzymes are cross-linked by a chemical comprising glutaraldehyde, 1,4-diisocyanatobutane, 1,2,7,8-diepoxyoctane and 1,2,9,10-diepoxydecane, or a combination thereof.

15. The method of claim 12 , wherein the electrode comprises platinum, gold, palladium, alloys of platinum, gold and palladium, or carbon based material.

16. The method of claim 12 , wherein the electrode comprises graphite or carbon nanotubes.

17. The method of claim 12 , wherein the polysaccharide comprises sucrose, trehalose, raffinose, or lactitol.

18. The method of claim 12 , wherein the biosensor measures both creatinine and creatine.

19. The method of claim 12 , wherein the biosensor measures creatine only or creatinine only.

20. The method of claim 12 , wherein the plurality of enzymes comprises a polyionic compound comprising polyethylenimine, poly(N-vinylimidazole), polypropyleneimine, polyallylamine, polyvinylpiridine, polyvinylpyrollidone, polylysine, protamine, or derivatives of polyionic compounds.

21. The method of claim 12 , wherein the electrode is exposed to a polysaccharide solution for at least 30 minutes.

22. The method of claim 12 , wherein the biosensor maintains a stable creatinine performance after 5 months of dry storage at ambient temperature and 21 days of use.

23. The method of claim 22 , wherein the stable creatinine performance comprises maintaining stable biosensor performance of greater than 400 pA/mg/dL after 5 months storage at ambient temperature and 21 days of use.

24. The method of claim 12 , wherein the polysaccharide is added to an enzyme solution before the enzyme solution is applied to the electrode to produce the plurality of enzymes.

25. The method of claim 12 , wherein the polysaccharide is applied to the electrode after the diffusion barrier is applied over the surface of the electrode.

26. The method of claim 12 , wherein both of the following are required: the polysaccharide is added to an enzyme solution before the enzyme solution is applied to the electrode to produce the plurality of enzymes and the polysaccharide is applied to the electrode after the diffusion barrier is applied to a surface of the plurality of enzymes.

27. The method of claim 12 , wherein the polysaccharide comprises 10% sucrose.

28. A disposable cartridge comprising multi-enzyme sensors, where a multi-enzyme sensor among the multi-enzyme sensors comprises:

an electrode;

a plurality of enzymes immobilized over a surface of the electrode;

a diffusion barrier over the surface of the electrode; and

a polysaccharide;

wherein the diffusion barrier comprises a polymeric compound selected from the group consisting of poly(tetrafluoroethylene) ionomers, the perfluorosulfonate ionomer NAFION®, poly-(2-hydroxymethyl methacrylate), polyvinyl chloride, cellulose acetate, and mixtures and copolymers thereof.

29. The disposable cartridge of claim 28 , wherein the multi-enzyme sensor comprises a creatine sensor.

30. The disposable cartridge of claim 28 , wherein the multi-enzyme sensor comprises a creatinine sensor.

31. The disposable cartridge of claim 28 , wherein an enzyme among the plurality of enzymes comprises creatininase.

32. The disposable cartridge of claim 28 , wherein an enzyme among the plurality of enzymes comprises creatinase.

33. The disposable cartridge of claim 28 , wherein an enzyme among the plurality of enzymes comprises sarcosine oxidase.

34. The disposable cartridge of claim 28 , further comprising a plurality of sensor arrays and calibration reagents, the plurality of sensor arrays comprising the multi-enzyme sensors.