Direct electrochemistry of cytochrome c on a multi-walled carbon nanotubes modified electrode and its electrocatalytic activity for the reduction of H2O2

Direct electrochemistry of cytochrome c (Cyt c), which was adsorbed on the surface of multi-walled carbon nanotubes (MWNTs), was investigated. The results from electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) suggested that Cyt c could be tightly adsorbed on the surface of MWNTs and MWNTs show an obvious promotion for the direct electro-transfer between Cyt c and electrode. A couple of well-defined and quasi-reversible CV peaks of Cyt c can be observed in a phosphate buffer solution (pH 7.0). Cyt c adsorbed on MWNTs exhibits a remarkable electrocatalytic activity for the reduction of hydrogen peroxide (11201). The calculated apparent Michaelis-Menten constant (K-m(app)) was 857 muM, indicating a high catalytic activity of Cyt c adsorbed on MWNTs modified electrode to the reduction of H2O2. Based on these, a third generation reagentless biosensor can be constructed for the determination of H2O2. (C) 2005 Elsevier B.V. All rights reserved.