Voltammetric oxidation of NADH at phenyl azo aniline/PEDOT modified electrode

Poly(3,4-ethylenedioxythiophene) (PEDOT) electrode, modified by the electrodeposition of 4-phenyl azo aniline (4-PAA) in which 4-PAA acts as mediator, was prepared by cyclic voltammetric procedure. Here after, the above modified electrode denoted as 4-PAA/PEDOT/GC modified electrode. The electrochemical properties and an effect of pH on the redox properties of 4-PAA/PEDOT/GC modified electrode were studied by cyclic voltammetrically and it was found that pH dependent electrode. The voltammogram shows that 4-PAA/PEDOT/GC modified electrode has surface confined character in KHP buffer solution. 4-PAA/PEDOT/GC electrode exhibits electrocatalytic activity towards the oxidation of NADH (dihydronicotinamide adenine dinucleotide) with an activation overpotential, which is ca 400 mV lower than bare electrode. In the 4-PAA/PEDOT/GC modified electrode, the PEDOT film plays important role to separate oxidation peaks of NADH and ascorbic acid (AA). The modified electrode exhibits stable FIA amperometric response and the detection limit was 50 nM in physiological pH.