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 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 (NO2−), nitrate (NO3−), 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 2×10−7 to 8.6×10−5 mol L−1, and the detection limit is 2×10−8 mol L−1. The liver mitochondria in Carassius auratus were isolated and ·NO release from mitochondria was monitored by using this ultramicroelectrode system.