Cyclic Voltammetry and Electrochemical Impedance Spectroscopy on the Interaction of Meldola's Blue and DNA

The interactions of Meldola's Blue(MB) and DNA were studied by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS).A couple of cyclic voltammetric peaks of MB decreased after MB interacted with dsDNA in the solution.The interaction between MB and dsDNA was an electrostatic mode.While MB interacted with ssDNA or dsDNA modified on the glassy carbon electrode,the peak currents of MB increased and the formal potential shifted negatively.Based on cyclic voltammetry,the binding constants of MB and ssDNA or dsDNA modified on the electrodes were determined to be 3.4×103 L·mol-1 and 5.2×103 L·mol-1,respectively.The electrostatic interaction existed between MB and surface-immobilized ssDNA,and both electrostatic and intercalative interactions occurred between MB and surface-immobilized dsDNA,which implied that MB might be used as a potential electrochemical DNA hybridization indicator.The experimental result of EIS was in consistent with that of CV.