Fabrication of electrodes modified with poly-3,4-ethylenedioxythiophene-polystyrene sulfonate film and study of their applicability in thiol-sensitive sensors

Abstract

Drop-by-drop deposition of an aqueous dispersion of poly-3,4-ethylenedioxythiophene-polystyrene sulfonate onto a glassy-carbon disk was used to fabricate electrodes modified with polymeric films of varied thickness. The modified electrodes were characterized by cyclic voltammetry on a rotating disk and electrochemical impedance spectroscopy. The fabricated electrodes were used to study the mechanism of oxidation of thiols in buffer solutions of thiocholine and cysteine by cyclic voltammetry on a rotating electrode, amperometry at a constant potential, and electrochemical impedancemetry. It was demonstrated that electrodes coated with a thin film of poly-3,4-ethylenedioxythiophene-polystyrene sulfonate can be used to determined thiols (thiocholine and cysteine) in buffer solutions by amperometry at a constant potential at concentrations in the range 5 × 10−6–10−4 M and by cyclic voltammetry at higher concentrations of 10−4-6 10−3 M.