NITRIC OXIDE SENSOR

1. A composition for measuring nitric oxide levels, the composition comprising ruthenium oxide nanoparticles, an electrically conductive powder, and a hydrophobic oil.

2. The composition of claim 1, wherein the electrically conductive powder includes a material selected from the group consisting of carbon, platinum, gold, and combinations thereof.

3. The composition of claim 1, wherein the weight ratio of ruthenium oxide nanoparticles to electrically conductive powder is from about 1:5 to about 1:7.

4. The composition of claim 1, wherein the hydrophobic oil is a perfluorinated oil.

5. The composition of claim 1, further comprising poly(ethylenedioxythiophene).

6. An electrode capable of detecting low levels of nitric oxide, the electrode comprising ruthenium oxide nanoparticles.

7. The electrode of claim 6, wherein the ruthenium oxide nanoparticles are dispersed throughout the electrode.

8. The electrode of claim 6, wherein the electrode comprises a core and a surface coating, the ruthenium oxide nanoparticles being located in the surface coating.

9. The electrode of claim 8, wherein the core is made from a material selected from the group consisting of carbon, platinum, gold, and combinations thereof.

10. The electrode of claim 8, wherein the surface coating has a thickness of from about 1 nanometer to about 1 micrometer.

11. The electrode of claim 8, further comprising a second coating, the second coating comprising poly(ethylenedioxythiophene).

12. The electrode of claim 11, further comprising a third coating, the third coating also comprising ruthenium oxide nanoparticles, the second coating being located between the surface coating and the third coating.

13. The electrode of claim 6, further comprising a membrane that is selective for nitric oxide, the membrane surrounding the electrode.

14. A method for modifying an electrode to detect low levels of nitric oxide, the method comprising:

providing an electrode and an acid solution, the acid solution comprising a ruthenium salt;

immersing the electrode in the acid solution; and

cycling the potential of the acid solution between a first potential and a second potential for a period of time to form a coating comprising ruthenium oxide nanoparticles on the electrode.

15. The method of claim 14, wherein the acid solution has a pH of from about 2.0 to about 3.0.

16. The method of claim 14, wherein the concentration of the ruthenium salt in the acid solution is from about 10 μM to about 50 μM.

17. The method of claim 14, wherein the first potential is about −0.85 V and the second potential is about +0.65 V, vs. Ag/AgCl.

18. The method of claim 14, wherein the potential is cycled at a rate of from about 80 V/sec to about 120 V/sec.

19. The method of claim 14, wherein the period of time is from about 15 minutes to about 30 minutes.

20. An electrode capable of detecting low levels of nitric oxide, the electrode having a first coating thereon, the first coating comprising poly(ethylenedioxythiophene).

21. The electrode of claim 20, further comprising a second coating, the second coating comprising ruthenium oxide nanoparticies.

22. The electrode of claim 20, wherein the first coating has a thickness of about 300 nanometers or less.

23. A method for detecting low concentrations of nitric oxide in a sample, the method comprising:

providing an electrode comprising ruthenium oxide nanoparticles; and

using the electrode to detect low concentrations of nitric oxide in a sample.

24. The method of claim 23, wherein the electrode is capable of detecting picomolar concentrations of nitric oxide.