The Construction And Application Of The Electrochemical Sensor Based On Metal Nanoparticles/Graphene Composites

Chapter 1:Firstly,the development,properties,preparation methods,functionalization principle,processing methods and applications of graphene were discussed.Secondly,the principle and applications of an electrochemical sensor were summarized.Meanwhile,the electrochemical aptasensor and its classification were introduced.The advantages and disadvantages of label or label-free electrochemical aptasensor were discussed.Finally,the research background,main contents and innovative points of this work were described briefly.Chapter 2:Herein,gold nanoparticles supported on Orange?functionalized graphene(AuNPs/O-GNs)were synthesized.The as-prepared nanocomposites were characterized by UV-vis absorption spectroscopy,transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)and cyclic voltammetry(CV).The nanocomposites integrate the high electrical conductivity of graphene,and the large specific surface area and excellent biocompatibility of AuNPs along with the electroactivity of Orange?.The AuNPs deposited on the O-GNs not only can enhance the conductivity AuNPs/O-GNs and improve the capability of electron transfer,but also can immobilize a large amount of aptamer.Orange?attached on the graphene surface can serve as both the stabilizer of graphene and the electrochemical probe for insulin detection.Based on AuNPs/O-GNs,a label-free electrochemical biosensor was constructed by immobilizing insulin binding aptamer on the surface of AuNPs/O-GNs modified electrode through Au-S bond.Based on the current changes caused by specific combination between insulin and aptamer,the content of insulin was detected.The biosensor exhibits good selectivity and high sensitivity at physiological pH value.The linear range is from 1.0×10-14 to 5.0×10-10 mol L-1 with a low detection limit of 6.0×10-15mol L-1(S/N=3).The recovery of insulin in human blood serum samples is from 102.3%to 104.7%.The developed sensor provides a strategy for routine monitoring of insulin in human serum samples in the future.Chapter 3:In this work,palladium nanoparticles on PDDA functionalized graphene nanosheets(PdNPs/PDDA-GNs)were synthesized through a hydrothermal process and NaBH4 reduction method.Then,the nanocomposites of PdNPs/PDDA-GNs were characterized by techniques of UV-vis,CV,TEM and XPS.The PdNPs/PDDA-GNs nanocomposites integrate the good conductivity and large surface area of graphene with the excellent catalytic activity of palladium nanoparticles(PdNPs).Based on PdNPs/PDDA-GNs,an electrochemical sensor was constructed for diclofenac sodium(DS)determination.Under the optimized experimental conditions,differential pulse voltammetry(DPV)was used to measure the electrochemical signal of DS.The linear range for DS is from 0.6 ?M to 40?M and the detection limit is 0.08 ?M(S/N=3).The proposed electrochemical sensor has good stability and high sensitivity,which will bring accurate detection for DS in pharmaceutical industries and in the future.Chapter 4:All the work did in this this paper is summarized.There are deficiencies still existing in the current job and the some possible methods are proposed.Finally,the prospect of electrochemical sensor is discussed.