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Three-dimensional interconnected network graphene foam (GF) was synthesized by chemical vapor deposition. The GF was transferred onto indium tin oxide glass, acting as an electrode for the selective determination of L-dopa in the presence of ascorbic and uric acid. Using differential pulse voltammetry (DPV) method, the oxidation peak current is well linear with L-dopa concentration in the range of 0.05-1 μM with a sensitivity of 2.64 μA μM−1 and in the range of 1-40 μM with a sensitivity of 1.82 μA μM−1. The detection limit of this electrode for L-dopa is about 20 nM. The proposed electrode can also effectively avoid the interference of ascorbic acid and uric acid, making the proposed sensor suitable for the accurate determination of L-dopa in human urine fluids. This electrode will have a wide range of potential application prospect in electrochemical detection. [ABSTRACT FROM AUTHOR]

An electrochemical sensor is described for simultaneous voltammetric determination of dopamine (DA) and uric acid (UA). It is based on the use of a nanomaterial composed of gold nanoparticles and 3-dimensional graphene (Au NP@3D GR). The 3D GR was prepared by chemical vapor deposition using nickel nanoparticles as the template at a temperature of around 900 °C. The surface of 3D GR contains oxygen-functional groups after treatment with acid. Carboxylated Au NP were self-assembled and anchored onto the surface of 3D GR. The nanomaterial was placed on a ITO electrode. The few-layer graphene on the ITO glass has a porous structure and the distribution of Au NP is uniform. The electrode shows a high sensitivity and a low detection limit for DA and UA. Figures of merit include detection limits of 0.1 M for DA and of 0.1 μM for UA, and well separated peaks at potentials of 0.18 and 0.30 V (vs. Ag/AgCl), respectively, at pH 7.0. The electrode has good repeatability and stability. [ABSTRACT FROM AUTHOR]