Application of double-impedance system and cyclic voltammetry to study the adsorption of fullerols (C60(OH)n) on biological peptide-adsorbed gold electrode

The adsorption of fullerols (C60(OH)n) on glutathione-adsorbed gold electrode was characterized by using double-impedance system, i.e., electrochemical quartz crystal impedance and electrochemical impedance spectroscopy, and cyclic voltammetry. The time courses of piezoelectric parameters were used to reflect the changes of interfacial physical properties, such as mass, density-viscosity, and dielectric constant, during the adsorptions of peptide and fullerols onto electrode. The electrochemical impedance based on the simple equivalent electric network were also simultaneously measured and provided electrochemical interface information, e.g., double-layer capacitance and charge-transfer resistance. It was found that the double-impedance responses were varied with the forms of glutathione. It was also shown that the frequency curves due to the adsorption of oxidized (GSSG) and reduced (GSH) glutathione could be exhibited as different kinetic equations. The heterogeneous charge-transfer rate constants of ferricyanide/ferrocyanide before and after the peptide and fullerols adsorption were determined by CV and EIS methods. The results showed that the proposed method has potential applications in interfacial studies of biomaterials, since these combined techniques have advantages in real time providing multidimensional piezoelectric and electrochemical impedance information.