The comparison of different gold nanoparticles/graphene nanosheets hybrid nanocomposites in electrochemical performance and the construction of a sensitive uric acid electrochemical sensor with novel hybrid nanocomposites.

In this paper, water soluble poly(diallyldimethylammonium chloride)-graphene nanosheets (PDDA-GNs) were synthesized and characterized by UV-visible absorption spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). On the basis of PDDA-GNs, three different types of gold nanoparticles/graphene nanosheets (AuNPs/GNs) hybrid nanocomposites were obtained by one-pot synthesis, in situ reduction and adsorption methods, respectively. These nanocomposites were used as electrode materials for electrochemical determination of uric acid (UA). The results indicated adsorption to be the best method to synthesize hybrid nanocomposites from the electrochemical point of view. Given the fact positively charged PDDA-AuNPs could interact with negatively charged UA molecules, we then synthesized PDDA-protected gold nanoparticles/graphene nanosheets (PDDA-AuNPs/GNs) hybrid nanocomposites by adsorption method, for the first time. As were expected, PDDA-AuNPs/GNs gave better performance for UA than AuNPs/GNs obtained by adsorption, and the anodic peak current of UA obtained by cyclic voltammetry (CV) increased 102.1-fold in comparison to bare GCE under optimizing conditions. Differential pulse voltammetry (DPV) was used to quantitatively determine UA. The linear range of UA was from 0.5μM to 20μM and the detection limit was 0.1μM (S/N=3) with a high sensitivity of 103.08μAμM(-1)cm(-2). The assay results of urine sample provided satisfying recoveries by standard addition method. In addition, the anodic peaks of adrenaline (AD) and UA were well resolved at PDDA-AuNPs/GNs modified electrode, while they were too overlapped to separate at bare electrode, as a result of that UA was successfully detected in the presence of AD. In conclusion, rapid synthesis of PDDA-AuNPs/GNs were realized and applied as an advanced hybrid electrode material for UA determination.