ELECTRODEPOSITION OF REDOX-ACTIVE FILMS OF DIHYDROXYBENZALDEHYDES ANDRELATED ANALOGS AND THEIR ELECTROCATALYTIC ACTIVITY TOWARD NADH OXIDATION

Dihydroxylbenzaldehyde (DHB) isomers can be oxidatively electrodeposit ed onto glassy carbon electrodes previously activated in base solution , We have studied the mechanism of such electrodeposition as well as t he 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-di hydroxybenzoic acid, 3,4-dihydroxyphenylacetic acid, and 4-nitrocatech ol, The electrodeposition process and the electrochemical behavior of the modified electrodes were strongly dependent on pH as anticipated f or quinone/hydroquinone functionalities. Glassy carbon electrodes modi fied with films derived from 2,3-DHB and 3,4-DHB exhibit catalytic act ivity in the electrooxidation of NADH, The catalytic currents are prop ortional 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. Thes e modified electrodes can be used in the design of biosensors based on coupled dehydrogenase enzymatic activities.