Electrodeposition of Redox-Active Films of Dihydroxybenzaldehydes and Related Analogs and Their Electrocatalytic Activity toward NADH Oxidation

Abstract

Dihydroxybenzaldehyde (DHB) isomers can be oxidatively electrodeposited onto glassy carbon electrodes previously activated in base solution. We have studied the mechanism of such electrodeposition as well as the electrochemical features of films derived from 2,3-DHB, 3,4-DHB, 2,5-DHB, and 2,4-DHB isomers as well as related analogs including 3,4-dihydroxybenzoic acid, 3,4-dihydroxyphenylacetic acid, and 4-nitrocatechol. The electrodeposition process and the electrochemical behavior of the modified electrodes were strongly dependent on pH as anticipated for quinone/hydroquinone functionalities. Glassy carbon electrodes modified with films derived from 2,3-DHB and 3,4-DHB exhibit catalytic activity in the electrooxidation of NADH. The catalytic currents are proportional to the concentration of NADH over the range 0.01−1.2 and 0.01−0.9 mM for films derived from 3,4-DHB and 2,3-DHB, respectively. These modified electrodes can be used in the design of biosensors based on coupled dehydrogenase enzymatic activities.