Sensitivity Electrochemical Immunosensors Based On Dual Signal Amplification Of Hybridization Chain Reaction And Nanoparticles

Nowadays,electrochemical immunosensor have made tremendous progress in the fields of agriculture,biomedicine,quality monitoring and environment.However,electrochemical immunosensors face many problems in practical analysis.To overcome these question,immunosensors are needed with high sensitivity and selectivity.In this text,several novel and high sensitive electrochemical immunosensors have been fabricated for the detection of C-reactive protein using hybridization chain reaction and nanoparticles amplification strategy.The dissertation contains four chapters and the contents are as follows:Chapter 1:Review about the progress of electrochemical immunosensors.Chapter 2:A sandwich electrochemical immunosensor was developed for detection of C-reactive protein based on hybridization chain reaction amplified signal.First,primary antibodies were immobilized on the surface of gold nanoparticles modified electrode;subsequently,the antigen and secondary antibody complexes were successively immobilized on the surface of the modified electrode,and a sandwich-type immune structure was formed through specific recognition of antigen-antibody.Finally,long DNA concatemers intercalating amounts of Ru Hex were linked to the sandwich-type structure via hybridization reaction.Differential pulse voltammetry?DPV?was used to record the oxidation signal of Ru Hex.Under optimal conditions,the immunosensor has achieved a wide linear range and low detection limit.Chapter 3:An electrochemical immunosensor for the determination of C-reactive protein was prepared using hybridization chain reaction and silver nanoparticles amplification strategies.First,silver nanoparticles were chosen as signal molecules,an amount of silver nanoparticles were absorbed or intercalated into the DNA concatemers,and the formed complex was used as signal probe.After that,it was connected to the prepared sandwich structure“primary antibody-antigen-secondary antibody complex”.Differential pulse voltammetry was used to record the change of the oxidation peak signal of silver nanoparticles.Under optimal conditions,the signal variation of the oxidation peak current was related to the logarithm of CRP concentration in the range of 0.5 pg mL^-1 to 75 ng mL^-1.The detection limit was obtained as low as 0.17 pg mL^-1.Chapter 4:A sensitive immunosensor for detect C-reactive protein was developed based on copper ion labeled functionalized silica spheres as signal probe.First,the gold nanoparticles were modified on the surface of bare glassy carbon electrode,and the primary antibody and antigen were linked to the surface of gold nanoparticles.Afterwards,a functionalized silica spheres-gold nanoparticles composites were used to load the secondary antibody and copper ions.The signal probe was linked to the target antigen via specifically recognition,thus,a sandwich immune complex was formed.Differential pulse voltammetry was used to record the response signal of the immunosensor.Under optimal conditions,the immunosensor had linear response range from 1.0 pg mL^-1 to 100 ng mL^-1 with the limit of detection of 0.33pg mL^-1.