Study On Label-free Electrochemical Immunosensor Based On Graphene Nanomaterials For HBsAg Detection

Recently,the research of electrochemical biosensors have gradually become a new popular research field.It based on the combination of immunoassay and electrochemical technology and gradually developed as a biosensor has the characteristics of low cost,high sensitivity,rapid analysis,high selectivity and simple operation.Among them,in the development of electrochemical sensors,graphene nanomaterials are widely used due to their special structures and properties such as large specific surface area,good catalytic properties and strong bioaffinity.In this paper,graphene and its derivatives were used to composited with other nanomaterials to complete the construction of the sensor's sensitive interface,so as to achieve the purpose of quantitative detection of Hepatitis B surface antigen?HBs Ag?.The main research contents as follows:?1?A highly sensitive,label-free immunosensor based on graphene oxide/Fe₃O₄/Prussian blue?GO/Fe₃O₄/PB?nanocomposite modified electrode was developeded for the determination of human hepatitis B surface antigen?HBs Ag?.In this electrochemical immunoassay system,the electrode modified material GO/Fe₃O₄ with good stability and large specific surface area was synthesized by solvothermal method.PB NPs were loaded to provide the signal of electrochemical immunoassay.Further,the electrodeposition of gold nanoparticles?Au NPs?on the surface of the modified electrode can not only immobilize HBs Ab,but also synergistically amplify the electrochemical signal of the system to improve the sensitivity of the sensor in detecting HBs Ag.HBs Ag was captured by specific immune reaction,which increased the electrode surface impedance,hindered the electronic transmission of PB,and caused the current signal to decrease.Under optimized conditions,the immunosensor exhibited a sensitive response to HBs Ag in the range of 0.5 pg m L^-1-200 ng m L^-1,and with a low detection limit of 0.166 pg m L^-1?/=3?.The experimental results show that the electrochemical immunosensor prepared by this method has high stability,excellent reliability,and has high potential application value in clinical immunoassay.?2?A novel,label-free electrochemical immunosensor based on the reduced graphene oxide-tetraethylenepentamine/Prussian blue?rGO-TEPA/PB?nanocomposite was designed and synthesized.In order to further improve the sensitivity of HBs Ag detection,a new rGO-TEPA/PB NPs was prepared,and the composite was modified with Au Pt bimetal core-shell material physically.Especially,rGO-TEPA/PB nanocomposites with large specific surface area and excellent conductivity can not only be used as the carrier of electrochemical redox probe PB,but also as an effective sensing platform to accelerate electron transfer.The combination of Au Pt NPs further improves the sensitivity and stability of the immunosensor.Meanwhile,a large amount of HBs Ab can be immobilized by Au-S or Pt-S covalent bond.Under optimal conditions,the immunoassay showed wide linear range from 0.25 pg m L^-1 to 800ng m L^-1and low detection limit of 0.08 pg m L^-1?/=3?.In addition,the method is also used for the analysis of human serum samples,and good agreement was obtained between the values and those of electro-chemiluminescence immunoassay?ECLIA?.