Voltammetric and quartz crystal microbalance studies of transition metal complex interactions with DNA

We report voltammetric studies of the binding of ferrocene-nucleobase conjugates to DNA in solution. Cyclic voltammetry and steady-state voltammetry at microelectrodes were utilised to determine the binding constants of the ferrocene-nucleobase conjugates to DNA. The binding constants of ferrocene-nucleobase conjugates to DNA was calculated from the changes in the diffusion currents with addition of DNA. Electroanalytical studies of the interaction of ruthenium(III)hexaamine with DNA immobilised on chemically modified gold and platinum electrode surfaces are also described. We have found that self-assembly of 4-mercaptopyridine on gold electrodes followed by methylation produces a surface which adsorbs DNA. Measurements of surface coverages of ruthenium(III)hexaamine were carried out by integrating the cyclic voltammogram and using quartz crystal microgravimetry by monitoring the frequency changes on addition of ruthenium(III)hexaamine to a solution containing a crystal with immobilised DNA. Crystal admittance measurements were consistent with rigid layer behaviour for the immobilised DNA.