Electropolymerization of β-cyclodextrin onto multi-walled carbon nanotube composite films for enhanced selective detection of uric acid

Abstract

An amperometric uric acid (UA) sensor incorporating a multi-walled carbon nanotubes (MWCNT) network in Nafion and electropolymerized β-cyclodextrin (β-CD) layer is investigated. The electrochemical sensor is comprised of a glassy carbon electrode modified with Nafion-MWCNT nanocomposite film, a β-CD polymer inner selective layer, and a Hydrothane polyurethane (HPU) outer selective coating. The surface morphology and electronic structure of the electrode material are characterized using transmission electron microscopy (TEM), scanning electron microscope (SEM), and Fourier transform infrared (FTIR) spectroscopy. The electrocatalytic activity of the sensor is studied using cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Analytical performance of the electrochemical sensor scheme with and without MWCNT and/or β-CD polymer is determined from direct UA injection during an amperometric analysis. The effective surface area is notably higher for Nafion-MWCNT coated glassy carbon electrodes, which in turn enhanced the sensitivity when coated with β-CD polymer. The results indicated an excellent electrocatalytic property of Nafion-MWCNT/β-CD film for UA detection with enhanced sensitivity (2.11μA·mM−1), wide linear responses over physiologically relevant concentrations, and fast response times. Enhancement is attributed to MWCNT offering increased electroactive surface area and the ability of β-CD to selectively sequester UA.