Sensitive detection of dopamine using a platinum microelectrode modified by reduced graphene oxide and gold nanoparticles

Platinum wire microelectrodes generally exhibited properties of low sensitivity but are easily contaminated where it comes to dopamine detection. In this paper, a platinum wire modified with gold nanoparticles (AuNPs) and reduced graphene oxide (rGO) was used to electrochemically detect dopamine in vivo. Electrochemical performances of microelectrodes (before and after surface modification) were investigated by impedance spectroscopy and cyclic voltammetry. The results showed that AuNPs/rGO composites significantly increase the electrode surface area and improve the electrocatalytic property of platinum wires. The modified electrodes exhibited excellent sensitivity for dopamine detection (LOD = 16.57 nM), as well as ascendant selectivity (simultaneous detection of ascorbic acid, dopamine, and uric acid), reproducibility (R.S.D. = 3.98%), and stability (>> 100 repetitive potential sweeps, 1-week lifespan). In vivo experiments showed that the proposed AuNPs/rGO electrode was also capable of detecting dopamine in complex physiological environments, particularly in the striatum of anesthetized rats. Hence, the proposed electrodes provided a potential application in in vivo multiplexing neurotransmitter detection in further research.