Three-dimensional graphene oxide foams loaded with AuPd alloy: a sensitive electrochemical sensor for dopamine

The authors describe a chemical sensor for dopamine (DA). It is based on the use of three-dimensional graphene oxide (3D rGO) loaded with varying amounts of AuPd bimetallic nanoparticles (3D rGO/AuPd NPs). The 3D rGO acts as an effective substrate providing a large surface area and allowing fast electron transfer. The interaction between 3D rGO and surface AuPd NPs increases the activity of the sensing material. These composites were fabricated as the active layer on an indium tin oxide for DA determination. The electrode showed the best performance at a working potential of 0.25 V (vs. the saturated calomel reference electrode) and a scan rate of 100 mVs^-1. The best electrode exhibits good sensitivity (4670 μA·mM^-1·cm^-2), a wide linear response (0.5 μM to 135 μM), and a low detection limit (0.2 μM). It is also selective, easily reproducible, and stable. It was applied to the determination of DA in spiked human serum and in clinical DA hydrochloride injections. The excellent performance of this electrode is attributed to the efficient electron transfer and large specific surface area of 3D rGO and to the high electrocatalytic activity of AuPd NPs due to the synergistic effect between the 3D rGO substrate and the AuPd alloy NPs. Graphical abstract An three-dimensional reduced graphene oxide (3D rGO) foam was loaded with AuPd bimetallic nanoparticles and applied to dopamine (DA) detection in human serum and an injection fluid.