Sensitive electrochemical determination of dopamine and uric acid using AuNPs(EDAS)–rGO nanocomposites

Here we report, the ultrasonication-assisted and N-[3(trimethoxysilyl)propyl]ethylenediamine] (EDAS) in the aqueous phase mediated the reduction of hydrogen tetrachloroaurate(III) trihydrate (HAuCl4·3H2O) and graphene oxide (GO) by a facile and environmentally benign “single-step one-pot approach”. EDAS, a kind of aliphatic amine, was utilized as a capping and stabilizing agent to prevent the aggregation of AuNPs in aqueous medium as well as functionalization of reduced graphene oxide (rGO). FTIR spectroscopy was used to examine the probable complexation mechanism occurring between Au ions and EDAS and their subsequent reduction to AuNPs on the surface of rGO. The size of AuNPs that formed on the surface of rGO was in the range of ∼5–8 nm. In the X-ray diffraction, the (111), (200), and (220) facets of AuNPs(EDAS) were observed along with the (002) plane of rGO. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometric (i–t) experiments were performed to characterize the prepared AuNPs(EDAS)–rGO nanocomposites utilized as an electrochemical sensor for the simultaneous detection of dopamine (DA) and uric acid (UA). In DPV, the peak separation between dopamine (DA) and uric acid (UA) was large up to 0.25 V. The calibration curves of DA and UA were obtained in the ranges of 0.05–11 μM and 0.1–11 μM with detection limits (S/N = 3) of 0.02 μM and 0.03 μM, respectively. Furthermore, this modified electrode was further applied to determine DA and UA in real samples with satisfactory results.