One-pot facile fabrication of graphene-zinc oxide composite and its enhanced sensitivity for simultaneous electrochemical detection of ascorbic acid, dopamine and uric acid

Reduced graphene oxide-zinc oxide (RGO-ZnO) composite was facilely fabricated by a spontaneous reduction of graphene oxide via zinc slice in one-pot approach at room temperature, and used to modify glassy carbon electrode (GCE) for developing of electrochemical biosensor (RGO-ZnO/GCE). The as-prepared RGO-ZnO was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and transmission electron microscope (TEM). It was revealed that the existence of ZnO in RGO-ZnO/GCE largely enhanced the electroactive surface area (EASA) and therefore the sensitivity for electrochemical sensing. In the mixtures of ascorbic acid (AA), dopamine (DA) and uric acid (UA), the biosensor exhibited three well-resolved voltammetric peaks (Delta EAA-DA= 236 mV, Delta EDA-UA = 132 mV, Delta EAA-UA = 368 mV) in the differential pulse voltammetry (DPV) measurements, allowing a simultaneous electrochemical detection of these biomolecules. The liner relationships between current intensities and concentrations were found to be 50-2350 mu M, 1-70 mu M and 3-330 mu M, with detection limits of 3.71 mu M, 0.33 mu M and 1.08 mu M for AA, UA and DA, respectively. The as-prepared RGO-ZnO/GCE biosensor displayed a good reproducibility and stability and was applied for detection of of AA, DA and UA in real plasma and urine samples with satisfying results. (C) 2015 Elsevier B.V. All rights reserved.