A multiwall carbon nanotubes film-modified carbon fiber ultramicroelectrode for the determination of nitric oxide radical in liver mitochondria.

A novel chemically modified electrode based on the multiwall carbon nanotubes (MWNTs) film-coated carbon fiber ultramicroelectrode (CFUE) has been described for the determination of nitric oxide radical (.NO). The electrochemical behaviors of MWNTs-modified CFUE have been characterized in 0.2 mmol L(-1) K(4)Fe(CN)(6) and 0.1 mol L(-1) KCl solution. The Nafion film was used to avoid some electroactive interferences. The amount of Nafion was optimized, and some possible interferents [such as nitrite (NO(2)(-)), nitrate (NO(3)(-)), ascorbate, dopamine (DA), l-arginine (l-Arg), etc.] were tested and evaluated. The oxidation peak current of .NO increases significantly at the MWNT/Nafion-modified CFUE, in contrast to that at the bare and the Nafion-modified CFUE, and the oxidation peak potential is at 0.78 V (vs. SCE), which can be used for the detection of .NO. The oxidation peak current is linearly with the concentration of .NO from 2x10(-7) to 8.6x10(-5) mol L(-1), and the detection limit is 2x10(-8) mol L(-1). The liver mitochondria in Carassius auratus were isolated and .NO release from mitochondria was monitored by using this ultramicroelectrode system.