The electrochemical polymerization of methylene green and its electrocatalysis for the oxidation of NADH

A poly(methylene green) thin film modified electrode was successfully prepared by means of electrochemical polymerization, which was carried out with cyclic voltammetric sweeps between −0.4 and +1.2 V (vs. SCE) at a glassy carbon base electrode in methylene green aqueous solution. The pH value of the solution notably affected the process of polymerization and the characteristics of the film. Compared with modified electrodes obtained by adsorption of methylene green in aqueous solution, this polymer modified electrode exhibited a higher stability and better catalytic activity for NADH. The peak potential shifted towards a positive direction for about 180mV in neutral medium. An obvious catalytic current could be observed for the oxidation of NADH, moreover, the polymer could reduce the oxidation overpotential of NADH by about 400 mV. The electrocatalytic current was proportional to the concentration of NADH, and a good linear relation from 0.5 to 10.0 mM with a correlation coefficient of 0.996 was obtained.