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 C-60 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 C-60 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) x 10(5) M-1 obtained in 5 mM NaCl in Tris-HCl buffer, and a dissociation rate constant from the dsDNA/Au surface of (1.2 +/- 10.1) x 10(-2) min(-1). (C) 2004 Elsevier B.V. All rights reserved.