Study Of Graphene Composite Electrochemical Sensor

Graphene nanomaterials have good biocompatibility,great surface area and high load capacity.In recent years,graphene has attracted great attention of researchers in the field of nanoscience and electroanalysis due to these excellent properties.In this dissertation,I will describe the construction of electrochemical biosensors based on graphene nanocomposites,silver nanoparticles dotted single walled carbon nanotubesreduced graphene oxide(AgNPs-SWCNTs-rGO)nanocomposite modified glassy carbon electrode(GCE);platinum nanoparticles loaded on nitrogen decorated reduced graphene oxide-single wall carbon nanotubes(N-r GO-SWCNTs-Pt NPs)nanocomposite modified GCE;gold nanoparticles dotted zinc oxide-reduced graphene oxide(AuNPs-ZnO-rGO)nanocomposite modified GCE.Completed high-sensitivity electrochemical detection of Piroxicam,daunorubicin,and 6-gingerol respectively.The specific topics of this thesis are as follows:(1)A GCE modified with AgNPs-SWCNTs-rGO nanocomposite had been developed for highly sensitive determination of Piroxicam.The synthesized nanocomposite was characterized by various techniques such as transmission electron microscopy(TEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The morphology and microstructure characterizations revealed that Ag NPs with an average diameter of about 6 nm were well dispersed and attached on the surface of SWCNTs-rGO composite.The electrochemical characterization showed that AgNPs-SWCNTs-rGO composite modified electrode exhibited excellent electrocatalytic activity toward the oxidation of Piroxicam.Under optimum conditions,the oxidation peak currents of Piroxicam were linearly dependent on its concentrations in the range of 1.5-400 ?M using linear sweep voltammograms(LSV),with detection limit of 0.5 ?M.Linear responses versus Piroxicam concentrations in the range of 0.05-250 ?M was obtained using the chronoamperometry method,with detection limit of 0.5 nM.The proposed electrochemical sensor was also used for the determination of the analytes in real samples and gave satisfactory results,with recoveries in the range from 99.4% to 104%.(2)In this report,a novel electrochemical sensor based on N-rGO-SWCNTs-Pt NPs nanocomposite was designed for the determination of daunorubicin.In the process,the reduction/doping of GO and the crystallization of the produced Pt were carried out concurrently in a one-step hydrothermal process.The fabricated N-rGO-SWCNTs-Pt NPs nanocomposite modified electrode was investigated by cyclic voltammetry(CV)and differential pulse voltammetry(DPV)and exhibited high sensitivity compared with unmodified electrode.Some experimental parameters which affected sensor response were optimized.Under optimum conditions,the fabricated sensor provided a low detection limit(0.02 ?M)with a wider linear range(0.1-10 ?M)and long-term stability.The proposed sensor was successfully applied for the sensitive and rapid determination of daunorubicin in human serum samples.(3)A GCE modified with AuNPs-ZnO-rGO composite had been developed for highly sensitive determination of 6-gingerol,Au NPs-ZnO-rGO nanocomposites were prepared by UV light reduction method.Based on the excellent performance of gold nanoparticles,zinc oxide and reduced graphene oxide,the sensor has showed good stability,selectivity and reproducibility.The linear range for detection of 6-gingerol concentration was: 0.1-100 ?M,with a detection limit of 0.03 ?M(S/N=3).The proposed sensor was successfully applied for the sensitive and rapid determination of 6-gingerol in ginger samples.