Application of double-impedance system and cyclic voltammetry to study theadsorption of fullerols (C-60(OH)(n)) on biological peptide-adsorbed gold electrode

The adsorption of fullerols (C-60(OH)(n)) on glutathione-adsorbed gold elec trode was characterized by using double-impedance system, i.e., electrochem ical quartz crystal impedance and elect ro chemical impedance spectroscopy, and cyclic voltammetry. The time courses of piezoelectric parameters were used to reflect the changes of interfacial physical properties, such as mas s, density-viscosity, and dielectric constant, during the adsorptions of pe ptide and fullerols onto electrode. The electrochemical impedance based on the simple equivalent electric network were also simultaneously measured an d provided electrochemical interface information, e.g., double-layer capaci tance and charge-transfer resistance. It was found that the double-impedanc e responses were varied with the forms of glutathione. It was also shown th at the frequency curves due to the adsorption of oxidized (GSSG) and reduce d (GSH) glutathione could be exhibited as different kinetic equations. The heterogeneous charge-transfer rate constants of ferricyanide/ferrocyanide b efore 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 t echniques have advantages in real time providing multidimensional piezoelec tric and electrochemical impedance information. (C) 2001 Elsevier Science L td. All rights reserved.