Electrocatalytic Oxidation of Dopamine, Ascorbic Acid and Uric Ac id at P oly-۴-Am inothiophenol on the Surfa ce of Ca rbon Nanotubes/GC Electrodes

During recent years, great efforts have been devot ed to the d evelopment of electrochemical sensors with electrosynthesized polymeric film electrodes. M odified elec trodes prep ared by electro polymerization have obvious advantages in the detection of analytes. For exa mple, it can accelerate transmission of electrons on the surface of electrode, it has high selectivity and sensitivity due to the film hom ogeneity in electroch emical depo sition, strong adherence to the electro de surface a nd large su rface area [۱-۲]. Unli ke conventional immobilization strategies for bio sensors, electropolyme rization has no limit in terms of the geometry and area of the electro de, and offers advantages with respect to thickness control, r eproducibility and uniform ity of the polymer film on the electrode surfaces with more complex geome tries. In additio n, electrop olymerization permits simple electrode re generation and can be easily extende d to the production o f microbiosensors. Many studie s have indicated that polymer film modified ele ctrodes show an en hanced res ponse for the determination of various importa nt biological and clinical species [۳].In this work, an el ectropolymerized film of ۴-aminothiophenol was prepared on the su rface of a GC electrode in ۰.۱۰ mol L-۱ HCl in methanol b y cyclic v oltammetry (CV). The poly(۴-aminot hiophenol) on the surf ace of GCE showed excellent catalytic activity toward oxidation of some biological compounds and con spicuously enhanced the redox peak currents. The ternary mixture, which contains ascorbic acid (AA), dopamine (DA) and uric acid (U A), can be well separated from each other at the surface of this modified electrode. The separ ations of the oxi dation peak potentials of AA-DA and DA-UA were ove r more than ۱۸۴ and ۱۴۷ mV, respectively. Using differential pulse vo ltammetry (DPV) technique, the calibratio n curves for AA, DA and UA were o btained over a wide range (۰.۵-۵ ۵ mM for AA, ۱۰-۵۰۰ µM for DA and ۰.۵-۷.۰ mM UA at the poly(۴-aminothi ophenol) modified GCE) and with the sensitivity of ۲۳.۸ ۹ µA/mM, ۰ .۲۰ µA/µM and ۲.۷۷ µ A/mM for AA, DA an d UA resp ectively. The theoretical lim its of detec tion defined as ۳s of the proposed method f or AA, DA and UA were ۰.۲۷ mM, ۳. ۷۳ µM and ۰.۲۹ mM, respectively. These results are somewhat si milar (or worse) performan ces (in som e cases) or superior ones (in most cases) than the previously reported modified electrodes in literatures [۴-۵].

کلیدواژه ها:

Electropolymerization ، carbo n nanotubes ، Electrocatalytic