Design of L-Cysteine Functionalized Au@SiO2@Fe3O4/Nitrogen-doped Graphene Nanocomposite and Its Application in Electrochemical Detection of Pb2+

摘要

A novel magnetic electrochemical sensor was designed for determination of lead ions based on gold nanoparticles(AuNPs)@SiO2@Fe3O4itrogen-doped graphene(NG) composites functionalized with L-cysteine.The Au@SiO2@Fe3O4/NG was synthesized by the electrostatic adsorption between AuNPs and SiO2-coated Fe3O4 NPs(SiO2@Fe3O4) and the amide bond between Au@SiO2@Fe3O4 and NG.L-Cysteine was successfully functionalized on the surface of Au@SiO2@Fe3O4/NG nanocomposites via the S-Au bond between L-cysteine and AuNPs.Owing to numerous active sites in L-cysteines and high conductivity of Au@SiO2@Fe3O4/NG composites,the proposed electrochemical sensor exhibited a well-distributed nanostructure and high responsivity toward Pb(Ⅱ).The sensor linearly responded to Pb2+ concentration in the range of 5-80 μg/L with a detection limit of 0.6 μg/L,indicating that this L-cysteine functionalized Au@SiO2@Fe3O4/NG composite could be a promising candidate material for the detection of Pb2+.