Fc-ssDNA conjugate: electrochemical properties in a borate buffer and adsorption on gold electrode surfaces

By using an electroactive species such as ferrocene (Fc), the electrochemical properties of bioorganic molecules were indirectly made accessible. 5'-Fc-NH-ssDNAs have a redox potential of 430-440 mV (vs. Ag\AgCl) in a borate buffer (pH 9), which is characteristic of ferrocene/ferrocenium. (Fc/Fc(+)) substituted by an amide group. The diffusion coefficient of Fc-ssDNA conjugates in a buffer solution was found to be 10(-7) cm(2) s(-1). 5'-Fc-NH-ssDNA-S-S-R (3) was adsorbed onto a gold microelectrode surface to form a self-assembled monolayer (SAM) via a disulfide linker with a high packing density. The Fc-electrophore allows the characterization of the SAM by cyclic voltammetry (CV). The rate constant of electron transfer through DNA was estimated to be 12 s(-1). (C) 2004 Elsevier B.V. All rights reserved.