A nitric oxide biosensor based on myoglobin adsorbed on multi-walled carbon nanotubes

Myoglobin (Myb) of horse heart is incorporated on multi-walled carbon nanotubes (MWNTs) and immobilized at a glassy carbon (GC) electrode surface. Its electrochemical behavior and enzyme activity are characterized by employing electrochemical methods. The results indicate that MWNTs can obviously promote the direct electron transfer between Myb and electrode, and that the Myb on MWNTs behaves as an enzyme-like activity towards the electrochemical reduction of nitric oxide (NO). Accordingly, an unmediated NO biosensor is constructed. Experimental results reveal that the peak current related to NO is linearly proportional to its concentration in the range of 2.0 x 10(-7)-4.0 x 10(-5) mol/L. The detection limit is estimated to be 8.0 x 10(-8) mol/L. Considering a relative standard deviation of 2.1% in seven independent determinations of 1.0 x 10(-5) mol/L NO, this biosensor shows a good reproducibility. The biosensor based on Myb/MWNTs modified electrode can be used for the rapid determination of trace NO in aqueous solution with a good stability, nice selectivity and easy construction.