Reduced graphene oxide supported monoclinic bismuth vanadate nanoparticles as an electrocatalyst for selective determination of dopamine in human urine samples

Abstract

WHO report says that 6.8 million people succumb to neurological disorders every year. For early detection of disease and disease diagnostic purposes, dopamine detection in bio fluid is inevitable in the medical field. In this work, BiVO4 and different amounts of rGO-loaded BiVO4 were synthesized by hydrothermal technique followed by reflux method. The different analysis confirms the formation of BiVO4 and rGO/BiVO4 nanocomposite. The electrochemical active surface area of glassy carbon electrode (GCE), BiVO4/GCE, 5rGO/BiVO4/GCE, 15rGO/BiVO4/GCE and 30rGO/BiVO4/GCE nanocomposite are 0.0747, 0.0585, 0.06696, 0.0714, and 0.0774 cm2 respectively. The 30rGO/BiVO4 nanocomposite showed a high electrocatalytic current towards the oxidation of dopamine. In pH 3 phosphate buffer solution (PBS), 30rGO/BiVO4 nanocomposite exhibited a higher catalytic current than pH (4–7) and pH 3 choose as an optimal pH for whole dopamine sensing. The oxidation of dopamine on the surface of 30rGO/BiVO4 is a diffusion-controlled process. The Rct value of 30rGO/BiVO4/GCE is low compared to other samples which enhances the electron transfer between the analyte and modified electrode. The 30rGO/BiVO4/GCE electrode exhibited, two dynamic linear ranges is 0.25–5 μM and 10–100 μM with a limit of detection of 0.098 μM and 0.713 μM. From the practical application point of view, the main co-existing interference signal is from ascorbic acid and uric acid. The 30rGO/BiVO4 showed a distinctive SWV peak for ascorbic acid and uric acid. In the urine samples, 30rGO/BiVO4/GCE nanocomposite showed more than 89% recovery for spiked dopamine.