Surface Modification of Solid Electrodes with Gliadin Biopolymer Film: A Permselective Membrane in Electrochemical Studies

Abstract

The application of natural materials films for the surface modification of glassy carbon and gold electrodes to enhance their selective sense in the electrochemical detection of organic and inorganic species is a major challenge. In this study, gliadin was extracted from wheat flour and, for the first time, applied as a novel biocompatible permselective modifier film on gold and glassy carbon electrodes for the electrochemical detection of various compounds. The structure and surface morphology of the extracted gliadin were investigated by Fourier transform infrared (FT-IR) spectroscopy and atomic force microscopy (AFM) techniques. AFM and scanning electron microscopy (SEM) showed that porous structures with high nanometric roughness were present in gliadin membranes prepared from the casting solution of gliadin in ethanol. Compared to hydrophobic ions, the capacitance (C) values of electrical double layers of gliadin film modified electrodes for hydrophilic ions were very high. The findings of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) proved high performance of gliadin membrane as permselectcive film for nominated cationic compounds with fast electrochemical kinetics responses in aqueous solutions (PBS, pH = 7). This behavior was verified by circulating solutions containing model compounds from a home-made continuous cell equipped with gliadin-modified polyamide membranes.