▎ 摘　　要

Gold nanoparticles (AuNPs) stabilized by citrate with different sizes (17, 28 and 46 nm) were assembled onto the poly(dimethyl diallyl ammonium chloride) (PDDA)-functionalized graphene nanosheets (GNS), respectively, and three kinds of Au/PDDA/GNS hybrids were thereby fabricated through electrostatic interaction. The structure, morphology and composition of the resulting hybrids were further characterized by transmission electron microscope (TEM), ultraviolet-visible (UV-vis) spectra, and X-ray photoelectron spectra (XPS) measurements. TEM characterization revealed that the AuNPs with the size of 17, 28 and 46 nm were densely dispersed onto the PDDA-functionalized GNS. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements showed that the obtained Au/PDDA/GNS nanocomposites with high electrocatalytic activity could simultaneously determine ascorbic acid (AA), dopamine (DA) and uric acid (UA). The high sensitivity towards DA and UA determination was due to the electrocatalytic effect of Au/PDDA/GNS hybrids and the electrostatic attractions between Au/PDDA/GNS and DA, Au/PDDA/GNS and UA. The proposed sensor exhibited good selectivity and sensitivity, and could be applied to determine UA in human urine with satisfactory results.