Sensitive detection of uric acid on partially electro-reduced graphene oxide modified electrodes

Reduced graphene oxide (RGO) material-based modified electrodes are increasingly employed as voltammetric sensors for detection of uric acid (UA), an important biologically active molecule. While substantial research efforts have used chemical doping, formation of hybrids to improve the electrocatalytic activities of RGO-related electrode films and thus the sensitivity for UA detection, little attention was paid to the effect of oxygen functionalities of RGO itself. Here, we demonstrate that the content of oxygen groups in RGO electrode films is an important determinant of the current response for UA oxidation on the RGO modified electrodes. To show this, RGO films with various amounts of oxygen functionalities were prepared through electro-reduction at different reduction potentials and their electrocatalytic activities for UA oxidation were examined in detail. The partially electro-reduced graphene oxide (pERGO) electrode film with intermediated content of oxygen functionalities was found to exhibit the highest current sensitivity towards the oxidation of UA. By using this class of pERGO modified electrodes, a simple voltammetric sensing platform for sensitive detection of UA was developed and adopt for analyzing UA in urine samples with satisfactory results. These findings highlight the important effect of oxygen groups in RGO film on the electrocatalytic property of RGO modified electrodes and thus can be helpful for the development of more sensitive RGO-based voltammetric sensors for other electroactive molecules. (C) 2013 Elsevier Ltd. All rights reserved.