Ácido Xanturênico: um novo mediador para a eletrooxidação de NADH

Abstract

The present work describes, for the first time, the preparation and use of a simple and efficient glassy carbon electrode (GCE) modified with multi-wall carbon nanotubes (MWCNT) and an activated-xanturenic acid (poly-XA) towards electrocatalytic NADH oxidation. For this purpose, initially, xanthurenic acid was activated in situ, generating a stable redox-active specie on the electrodic surface, which presented electrocatalytic activity towards the oxidation of NADH. The techniques used for the accomplishment of this work were the cyclic voltametry and cronoamperometry, which were used to study the behavior of the modified electrodes, for the experimental parameters optimization, for the attainment of the kinetic parameters and analytical characterization of the sensors. Hydrodynamic and cronoamperometric studies were carried out with the aim to get information on the oxidation process of NADH on the modified electrode. Through the Koutech-Levich and Cotrell plots it was possible to obtain the values for the diffusion coefficient (D) and the kinetic constant of the catalytic reaction (k) for the analyte in study. The values of the diffusion coefficient and k, determined for NADH were 2,4x10-6 cm2 s-1 and 7,82 x104 L mol-1 s-1, respectively.