Effect of Surface Hydrophilicity of an Indium Oxide Electrode on Direct Electron Transfer of Myoglobins

Effect of hydrophilicity of the surface of an In2O3 electrode on the electrode reaction of myoglobins was clearly demonstrated for the first time. At the highly hydrophilic surface of an In2O3 electrode, well-defined redox waves of myoglobins from both horse heart and sperm whale skeletal muscle were observed with the heterogeneous electron transfer rate constants (k°′) of ca. 3 × 10−4 and 1 × 10−4 cm s−1 at pH 6.5, respectively.