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 nanombes (MWNTs) film-coated carbon fiber ultramicroelectrode (CFUE) has been described for the determination of nitric oxide radical (center dot NO). The electrochemical behaviors of MWNTs-modified CFUE have been characterized in 0.2 mmol L-1 K4Fe(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 (NOD, nitrate (NOD, ascorbate, dopamine (DA), L-arginine (L-Arg), etc.] were tested and evaluated. The oxidation peak current of center dot 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 center dot NO. The oxidation peak current is linearly with the concentration of center dot NO from 2 x 10(-7) to 8.6 x 10(-5) mol L-1, and the detection limit is 2 x 10(-8) mol L-1. The liver mitochondria in Carassius auratus were isolated and center dot NO release from mitochondria was monitored by using this ultramicroelectrode system. (c) 2004 Elsevier B.V. All rights reserved.