Detection Of Aβ By Electrochemical Immunosensor Based On Dual Signal Amplification Strategy

Alzheimer’s disease（AD）is an age-related neurodegenerative disease that affects more than 50 million people worldwide.AD is primarily caused by the accumulation of amyloid beta protein（Aβ）in the brain,which is not only a therapeutic target but also a biomarker used to diagnose certain diseases.Electrochemical immunosensor is a kind of analytical tool developed based on the specific recognition function of antigen and antibody.It has the advantages of fast analysis speed,high sensitivity,strong specificity and low cost.In this study,noble metal nanocomposites with high catalytic performance were developed to construct electrochemical immunosensors based on the dual-signal amplification strategy,and achieved rapid and sensitive detection of Aβsuccessfully.The research includes two components:（1）An electrochemical immunosensor based on Pt Cu BP MNPs/NB-Mo S₂ was constructed by dual signal amplification strategy,and achieved quantitative detetion of Aβ.Although the noble metal Pt had strong catalytic performance,biocompatibility and conductivity,it had the disadvantages of high cost and low atom utilization.Alloying with transition metal Cu could effectively reduced the cost and improve the utilization rate of Pt atom.Meanwhile,doping non-metallic elements of B and P was able to optimize the material morphology.The designed small size mesoporous nanospheres Pt Cu BP had large specific surface area and rich pores,which could realize the amplification of the electrocatalytic signal of H₂O₂.In order to avoid the agglomeration of small size Pt Cu BP MNPs due to their high surface free energy,two-dimensional layered Mo S₂ with large surface was used to uniformly immobilize Pt Cu BP MNPs,which increased the number of catalytic active sites per unit area.Meanwhile,the doping of N and B improved the catalytic capacity of Mo S₂ and further amplified the electrocatalytic signal.The Pt Cu BP MNPs/NB-Mo S₂ electrochemical immunosensor based on dual signal amplification strategy was applied to the analysis and detection of Aβ,showed a wide linear detection range of 100 fg/m L～100 ng/m L and a low detection limit of 47.6 fg/m L.（2）On the basis of the above study,we further improved the utilization rate of Pt atoms by alloying bimetallic of Cu and Co,and enhanced the catalytic capacity of GO by doping N and B.An electrochemical immunosensor based on Pt Co Cu PNPs/NB-r GO was constructed by dual signal amplification strategy,and achieved quantitative detetion of Aβ.The designed popcorn structure Pt Co Cu had larger surface area and higher porosity,which could expose more active sites and accelerate electron transfer.The alloying of Cu and Co improved the utilization rate of Pt atom and produced higher catalytic performance than Pt.The N and B doped GO showed similar catalytic performance to the noble metal Pt,which was able to effectively cooperate with Pt Co Cu PNPs to catalyze H₂O₂ and achieved further amplification of electrocatalytic signal.The sensitivity of the immunosensor was improved.In addition,Pt Co Cu PNPs and NB-r GO could fix a large number of antibodies via M（Pt,Co,Cu）-N and amide bonds respectively,which provided a guarantee for the specific binding between the antigen and antibody.The Pt Co Cu PNPs/NB-r GO electrochemical immunosensor based on dual signal amplification strategy was applied to the analysis and detection of Aβ,showed a wide linear detection range of 50.0 fg/m L～100 ng/m L and a low detection limit of 3.50 fg/m L.