Synthesis And Electrochemical Sensing Application Of Silver And Graphene Nanomaterials

Silver nanoparticles have been extensively applied in many fields because of their unique quantum confinement effect,catalytic performance,strong adsorption capacity and surface effect.Graphene quantum dots(GQDs)have excellent performances due to quantum confinement and edge effects.Dopamine nanospheres(DNS)could be used as excellent carriers for loading different signal molecules or tags because of their good monodispersity,large surface area and versatility for surface functionalization.Dopamine nanospheres(DNS)can be good candidates as carriers for developing ultrasensitive electrochemical sensor because of their good monodispersity,large surface area and versatility for surface functionalization.This paper synthesized Silver nanocubes(AgNCs),graphene quantum dots(GQDs)and DNS.These nanomaterisls were used to construct the enzyme-free sensor for the detection of hydrogen peroxide(H₂O₂),Flutamide(FLT),dopamine(DA)and uric acid(UA).(1)The GQDs and AgNCs were synthesized by a hydrothermal method and characterized by UV-Vis and fluorescence(FL)spectra,Fourier transform infrared(FT-IR)spectroscopy,transmission electron microscopy(TEM)and scanning electron microscopy(SEM).The GQDs and AgNCs modified gold electrode(GE)possesses well conductivity by electrochemical impedance spectroscopy(EIS).The Chit-GQDs/AgNCs/GE displays good electrocatalytic activity towards the reduction of hydrogen peroxide(H₂O₂),and can be used as a novel and sensitive enzyme-free H₂O₂sensor.According to the amperometric experiments,the sensor exhibits a rapid response,a wide linear range from 10?M to 7.38 m M,a low detection limit of 0.15?M and high selectivity,as well as good repeatability to H₂O₂determination.(2)This work presents an excellent DA and UA sensor based on a gold electrode modified with carboxylic acid functionalized graphene(CFG)and dopamine nanospheres functionalized with silver nanocubes(AgNCs-DNS).We assembled the CFG on an Au electrode via covalent bond by using cysteamine as a cross-linker.In addition,CFG was easily coated with AgNCs-DNS at room temperature.The nanocomposite was characterized by SEM,and the electrochemical behavior of the AgNCs-DNS/CFG modified electrode was evaluated by cyclic voltammetry(CV)and differential pulse voltammetry(DPV).The AgNCs-DNS/CFG modified electrode exhibited linear ranges of 2.5-130.0?M and10.0-130.0?M with detection limits of 0.25?M and 1.9?M for DA and UA,respectively.The results indicated that the composite presented here is a promising substrate for use in electrochemical sensing.(3)In this study,Polydopamine(PDA)functionalized silver nanoparticles nanocomposite(PDA-AgNPs)modified gold electrode was prepared by polymerization method and chemical reduction.The structure and morphology of PDA-AgNPs were characterized by SEM.DPV and CV were used to characterize electrochemical properties of the modified electrode.The fabricated sensor showed a good linear relationship within the range of 0.0016 m M?0.070 m M,the detection limit of 2.4?M(S/N=3),as well as good repeatability to FLT determination.These results indicate that the PDA-AgNPs nanocomposites are promising candidates for the detection of FLT.