An Electrochemical Study on the Interaction between Thionine and DNA

The interaction of thionine with DNA was studied by cyclic voltammetric and a.c. impedance methods. As a consequence of the interaction between thionine and DNA, an increment in impedance was observed for the thionine _ modified self _ assembled gold electrode as well as for the thionine _ or DNA _ modified glassy carbon electrodes. Changes in peak potential and peak current occurred, after the adsorbed thionine reacted with DNA adsorbed on glassy carbon electrodes. Our spectroscopic results suggest that intercalation and electrostatic forces bind thionine and DNA molecule up in PBS buffer. The apparent equilibrium constant was found to be 4.9×104 L·mol-1. The reaction rate between thionine and DNA depends upon their anchor sites on the electrode. Thionine _ modified gold electrodes were prepared by a self _ assembly technique, whereas DNA _ and thionine _ modified carbon electrodes were obtained by adsorption. Both cyclic voltammetry and electrochemical impedance method have been proved to be cheap, rapid and simple methods for the characterization of interactions between small molecules and DNA.