Studies on the Recognition Interaction of Rhodamine B and DNA by Voltammetry

The recognition interaction of Rhodamine B(RB) with DNA was studied in a Britton-Robinson (B-R)buffer solution with pH=7.5 at a glassy carbon electrode by electrochemical techniques. RB shows an irreversible oxidation peak at 0. 92 V(vs. SCE). After the addition of DNA inthe RB solution, the peak current of RB decreased apparently without the shift of the peak potential. The electrochemical parameters such as the charge transfer coefficient a and the electrode reaction rate constant k' of the interaction system were carefully studied. The parameters did not change before and after the addition of DNA, which indicated that an electrochemical non-active complex had been formed, so the concentration of RB in the solution decreased and the peak current decreased correspondingly. The binding ratio of RB to DNA was 2:1 with a binding constant of 2.66×109.