Studies on electrochemical properties and scavenge of superoxide anion in aprotic media by using carbon nanotubes powder microelectrode

Multiwall carbon nanotubes (MWCNTs) are filled in the cavity at the tip of a microelectrode to form a carbon nanotubes powder microelectrode (CNTs-PME). CNTs-PME was used to study electrochemical properties of superoxide anion in aprotic media. The reversibility of the oxygen/superoxide anion couple (O-2/O-2(-)) at the different powder microelectrode in different aprotic media was compared by cyclic voltammetry (CV). The result indicated that the nearly reversible redox process of the O-2/O-2(-) couple was obtained at a CNTs-PME. The heterogeneous electron transfer rate constant (k(s)) can be measured by steady-state voltammogram and the result is 4.7 x 10(-3) cm s(-1), suggesting that the electrode reaction is a nearly reversible process as expected. The scavenging activities of bilirubin, alpha-tocopherol (vitamin E), are examined, and the experimental results confirm that a-tocopherol is the better scavenger toward O-2(-) between them. (C) 2003 Elsevier B.V. All rights reserved.