Novel nitric oxide microsensor and its application to the study of smooth muscle cells

A novel sensitive, selective and stable nitric oxide (NO) microsensor is described, which is modified by nano Au colloid and Nafion. As determined by atomic forced microscopy (AFM), the diameter of Au colloid particles is from 7 to 14 nm. The detection of NO is based on the nano Au particles catalysis of NO oxidation at an anodic potential of +0.74 V (versus saturated calomel electrode (SCE)). The microsensor showed a low detection limit, high selectivity and sensitivity for NO determination. The oxidation current (measured by differential pulse amperometric technique) was linear with NO concentration ranging from 1.0×10⁻⁷ to 4.0×10⁻⁵ mol/l with a calculated detection limit of 5.0×10⁻⁸ mol/l (S/N=3). Using the microsensor, the direct real time production of NO in the smooth muscle cells was continuously measured, which showed the NO levels was increased by stimulating with l-arginine (l-Arg), acetylcholine (Ach) and a self-made flavonoid medicine.