Interactions between DNA and a water-soluble C60 derivative studied by surface-based electrochemical methods

A novel electrochemical micromethod for the investigation of the interactions between DNA and non-electroactive species is described. The method was developed using the system of double-stranded DNA (dsDNA) modified gold electrodes (dsDNA/Au), a synthesized water-soluble C60 derivative as a model, and [Co(phen)3]3+/2+ (phen=1,10-phenanthroline) as an electroactive indicator. Electrochemical studies with dsDNA-modified gold electrodes suggest that the C60 derivative can interact strongly with dsDNA, with binding sites of the major groove of the double helix and phosphate backbone of dsDNA, a binding constant of (1.6 ± 0.2) × 105 M−1 obtained in 5 mM NaCl in Tris–HCl buffer, and a dissociation rate constant from the dsDNA/Au surface of (1.2 ± 0.1) × 10−2 min−1.