Facile synthesis of Au-graphene nanocomposite for the selective determination of dopamine

Abstract

In this study, an ultrasensitive electrochemical biosensor for dopamine, which was based on graphene/gold nanocomposite, has been developed. Dopamine (DA) is an important neurotransmitter compound in the mammalian central nervous system because the loss of dopamine containing neurons brings about some serious disease. Therefore, it is very important to develop a selective and sensitive sensor for the analysis of DA in an excess amount of ascorbic acid (AA). Here, we present a facile strategy for the deposition of gold nanoparticles on graphene sheets with high reproducibility. The graphene oxide is synthesized by the modified Hummers method and reduced by chemical and thermal methods after deposition of gold nanoparticles. The graphene/gold nanocomposites were prepared using sodium hydroxide acting as an accelerator for the reduction of gold ions. The possible formation mechanism of graphene/gold nanocomposites without any reducing agent, for example, NaBH4 and sodium citrate etc., was also discussed. The composition and electrochemical properties of the resulting materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), raman spectroscopy, thermogravimetric analyzer (TGA), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Also, transmission electron microscope (TEM) was employed to demonstrate the successful deposition of gold nanoparticles on the surface of graphene sheets. In comparison to the reduced graphene oxide (rGO) modified electrode, the graphene/gold nanocomposite modified electrode shows superior performance. The modified electrode showed a low detection limit (0.208 μM), an enhanced electrocatalystic current for DA, and a good separation of potential of DA and AA.