▎ 摘　　要

By exploiting the electrostatic interaction between positively charged 3,4-ethylenedioxythiophene cation radicals and negatively charged sulfonated graphene (SG) sheets, we prepared a poly(3,4-ethylenedioxythiophene)-sulfonated graphene (SG-PEDOT) composite film by a one-step electrochemical process. The composite was further decorated with gold nanoparticles (AuNPs) and employed as an electrode material for the detection of L-cysteine (Cys). The SG-PEDOT composite film is shown to provide a rough surface for the electrodeposition of AuNPs and to improve substrate accessibility and interaction with Cys. Moreover, the AuNPs-decorated composite exhibits better electrocatalytic performance than that of a SG-PEDOT composite only. Under optimum experimental conditions, the amperometric current of the sensor is linearly related to the concentration of Cys in the 0.1 to 382 mu M range, and the detection limit is 0.02 mu M (at S/N=3). The modified electrode displays favorable selectivity, good stability and high reproducibility. The method was successfully applied to the detection of Cys in spiked human urine.