The Research Of Electrochemical Immunosensors Basing On Functional Noble Metal Composite Nanomaterials For Amplified Signal

Electrochemical immune sensing analysis technology is a rapid and sensitive detection method for quantitative detection tumor markers,which based on biological molecular specificity immune recognition to generate immune complex and obtain electrochemical signal.Electrochemical immune sensing analysis technology with high sensitivity,high specificity and economic efficiency has caused widely interesting.As a detection method,it is widely used in disease diagnosis,environmental monitoring and food safty inspection field.Functional nanomaterials are applied in fabrication of electrochemical immunosensor,which can amplify detection signals and improve the sensitivity of sensor for high sensitivity of quantitative detection of tumor markers.In this study,electrochemical immunosensors are fabricated for the quantitative detection of tumor marker,which based on four noble metal composite nanomaterials,platinum hybrid multiwalled carbon nanotubes adhered copper oxide?Pt@CuO-MWCNTs?,biotin-functionalized amination Fe₃O₄ nanoparticle?B-APTES@Fe₃O₄?,silver nanoparticles decorated L-cysteine capped gold nanoparticles?Au-cye-Ag?,bimetallic nanoparticles hybridized GS-SnO₂?GS-SnO₂-BMNPs?.There are three kind of electrochemical immunosensors are fabricated based on aforementioned four noble metal composite nanomaterials as labels,which have large specific surface area and good electrocatalysis for high sensitivity of quantitative detection of?-fetoprotein?AFP?,and simultaneous detection Hepatitis B e-antigen?HBe-Ag?and Hepatitis B surface antigen?HBs-Ag?.The main researches are concluded as follows:In the first part,an electrochemical immunosensor has been assembled to detect AFP.?-cyclodextrin functionalized graphene?CD-GS?with good dispersibility was used as platform for capturing primary antibodies?Ab₁?.The Pt@CuO-MWCNTs was used to label labelling antibodies?Ab₂?.Pt@CuO-MWCNTs exhibit excellent electrocatalytic activity,and produce high electrical signal to improve the sensitivity of electrochemical immunosensor.The immunosensor exhibits a relatively wide linear range(1 pg·mL^-10.5 ng·mL^-1 and 0.5ng·mL^-120 ng·mL^-1),high sensitivity and a low detection limit of 0.33 pg·mL^-1.The immunsensor also shows good reproducibility and stability,which indicates an enormous application prospect for detection AFP or diagnosis of liver cancer.In the second part,a novel immunoassay sensor was designed for sensitive electrochemical detection of AFP based on a?biotin-streptavidin-biotin??B-SA-B?strategy using the electroplating gold as sensor platform,B-APTES@Fe₃O₄ as labels and streptavidin?SA?as bridges.The B-APTES@Fe₃O₄ closely combines with biotinylated secondary antibodies?B-Ab₂?through the interaction between streptavidin?SA?and biotin,which fabricates the B-SA-B strategy.The cross-shaped SA with four free biotin-binding site can combine with 3 equimolar ratio of B-APTES@Fe₃O₄.As a result,triple signal amplification can be achieved based on one layer of SA.The proposed immunosensor reflects excellent analytical performance for the measurement of AFP with wide range linear(1 pg·mL^-10.5ng·mL^-1 and 0.5 ng·mL^-110 ng·mL^-1),low detection limit(0.33 pg·mL^-1),good sensitivity,reproducibility and stability,which has an expansive application prospect for detection AFP or diagnosis of liver cancer.In the third part,a novel electrochemical immunosensor based on thionine?Thi?and ferrocene?Fc?functionalized GS-SnO₂-BMNPs as labels was fabricated for simultaneous determination of HBe-Ag and HBs-Ag.Specifically,Thi and Fc functionalized the bimetallic NPs including silver nanoparticles decorated L-cysteine capped gold nanoparticles?Au-cys-Ag?and gold hybrid platinum nanoparticles?Au@Pt?loaded GS-SnO₂ attached with HBe labelling antibody?HBe-Ab₂?and HBs labelling antibody?HBs-Ab₂?,which were used as immune probes for detecting HBe-Ag and HBs-Ag,respectively.The two immune probes can generate two separate signal peaks without mutual interference at the same time,which meet the requirement of simultaneous determination.The developed immunosensor could reveal a wide linear range(0.01¹00 ng·mL^-11 for the detection of HBe-Ag;0.01¹00 ng·mL^-1 for HBs-Ag)with a low detection limit(4.679 pg·mL^-1 for HBe-Ag and 4.665 pg·mL^-1 for HBs-Ag).The method with satisfactory reproducibility and selectivity has an expansive application prospect in the diagnosis of hepatitis B.