Electrochemical sensor for epinephrine based on a glassy carbon electrode modified with graphene/gold nanocomposites

A solution-based approach of chemical co-reduction of Au (III) and graphene oxide (GO) was used to prepare graphene/Au (GR/Au) nanocomposites. The gold nanoparticles (nano-Au) integrated in GR acted as spacers for inhibiting the aggregation of GR sheets. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) results revealed that nano-Au particles were dispersed uniformly on the GR sheets. The obtained GR/Au nanocomposites modified glassy carbon electrode (GR/Au/GCE) exhibited high sensitivity in the detection of epinephrine (EP). It has been found that oxidation of EP at this modified electrode occurred at less positive potentials than on bare GCE. The anodic peak current observed were directly proportional to EP concentration between the range of 5.0 × 10−8 and 8.0 × 10−6 mol L−1 (L.O.D. = 7.0 × 10−9 mol L−1). In addition, the oxidation peaks of EP and ascorbic acid (AA) were separated from each other by approximately 180 mV. Therefore the GR/Au nanocomposites modified electrode successfully differentiates the signals of the two analytes. At the same time, this electrode also showed favorable electrocatalytic activity toward some other small biomolecules (such as dopamine, β-nicotinamide adenine dinucleotide, and uric acid), suggesting the potential applications of GR/Au nanocomposites for constructing biosensors.