Abstract: 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^s 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.

Key words: Rhodamine B, DNA, Recognition interaction, Electrochemical behavior