The Investigation Of Electrochemical Biosensors Based On Graphene Composites

Graphene as a new type of carbon nano-materials received extensive attention of the researchers in various fields,due to its superior characteristics including ultrahigh carrier mobility,huge specific surface area,higher thermal conductivity,great mechanical strength,high thermal stability,etc.Electrochemical biosensor,which have the advantages of low cost,high sensitivity,fast current response and simple to operate,have been widely applicated in analysis and detection of clinical samples.In this thesis,two kinds of graphene nanocomposites(CuI/Gr and Cu2S/RGO)are prepared.The as-prepared nanocomposites are characterized by scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS).Sequentially,a high-sensitive nonenzymatic hydrogen peroxide(H2O2)biosensor based on cuprous iodide and graphene(CuI/Gr)nanocomposites has been explored for the detection of H2O2 released by living cells.The observations demonstrate that the CuI/Gr nanocomposites modified glassy carbon electrode(GCE)exhibits excellent catalytic activity for H2O2 with a high sensitivity,a relatively low detection limit,a wide linear range and an outstanding reproducibility,which could be used to detect H2O2 release from different kinds of living cells under stimulation while eliminating the interference of ascorbic acid.Furthermore,a novel dopamine biosensor based on carbon fiber microelectrodes(CFMEs)modified with copper sulfide(I)functionalized nanocomposites of reduced graphene oxide(Cu2S/RGO)has been explored for sensitive detection of neurotransmitters.The as-prepared Cu2S/RGO decorated microelectrodes(Cu2S/RGO-CFMEs)are characterized by scanning cyclic voltammetry.The observations demonstrate that Cu2S/RGO-CFMEs display excellent catalytic activity and high selectivity for dopamine with a relatively low detection limit,a wide linear range and an outstanding reproducibility.The as-prepared dopamine biosensor with high sensitivity also shows the promising application in the in vivo measurements of neurotransmitters.