The effect of calcium ions on the electrocatalytic oxidation of NADH by poly(aniline)-poly(vinylsulfonate) and poly(aniline)-poly(styrenesulfonate) modified electrodes

Abstract

Addition of Ca²⁺ ions increases the electrocatalytic response towards NADH at poly(aniline)–poly(vinylsulfonate) and poly(aniline)–poly(styrenesulfonate) modified electrodes by up to 12 and 25 times, respectively. This enhancement effect is reproducible and reversible. Measurement of the amount of charge passed through the polymer film in the presence of Ca²⁺ indicates a correlation between the total amount of Ca²⁺ incorporated within the polymer film and the magnitude of the enhancement of the electrocatalytic current for NADH oxidation at the polymer film. In addition, ³¹P-NMR studies show that the amount of NADH bound within the poly(aniline) film is increased significantly when Ca²⁺ is present. These results suggest that the enhancement of the NADH oxidation current at poly(aniline) modified electrodes caused by Ca²⁺ is due to an increase in the partition of NADH into the polymer film and/or an increase in the binding affinity of the polymer for NADH.