Study And Application Of Electrochemical Analysis Sensing Strategies Based On Noble Metal Nanocomposites

Noble metals and their nanocomposites have attracted much attention due to their unique physical and chemical properties such as large specific surface area,high surface reactivity,abundant active sites and high catalytic efficiency.Noble metal nanocomposites have the advantages of both noble metals and nanomaterials,and show strong catalytic and conductive properties.Using the prepared noble metal nanocomposites,a variety of electrochemical analysis sensing strategies were constructed.Several electrochemical immunosensors and electrochemical aptasensors were prepared to detect human tissue polypeptide antigen,alpha-fetoprotein,carcinoembryonic antigen,thrombin and lead ions efficiently,sensitively and rapidly.These fabricated electrochemical biosensors provide methods and bases for clinical diagnosis in biomedical field and environmental pollutant detection and analysis in environmental protection field.The detailed works are as follows:?1?A general electrochemical immunosensing strategy was constructed for the sensitive detection of human tissue polypeptide antigen?HTPA?.Three-dimensional ordered porous gold film?3D-MGM?owned good conductivity and could be used as a substrate to capture antibodies.Dual-functional nano-Au/Pt/Au?BiR-NRs?possessed high electrocatalytic activity and large specific surface area.It was used to label signal antibody?Ab₂?to catalyze hydrogen peroxide and the signal amplification was realized successfully.The designed immunosensor showed good linear range?0.001-15.0 ng/mL?,low detection limit?0.7 pg/mL?and practical sample analysis ability.?2?Multifunctional graphene nanocomposites?TB-Au-Fe₃O₄-rGO?was used to modify electrodes for amplifying electrochemical signals.A novel label-free electrochemical immunosensor for quantitative detection of alpha-fetoprotein?AFP?was constructed.TB-Au-Fe₃O₄-rGO combined the advantages of graphene,Fe₃O₄,Au nanoparticles and toluidine blue.Because of the good electrochemical performance of TB-Au-Fe₃O₄-rGO,the constructed electrochemical immunosensor could detect AFP sensitively.Under the optimum conditions,the immunosensor showed good reproducibility,selectivity and stability,which provided potential applications for the clinical diagnosis of other tumor markers.?3?Flower-like Ag/MoS₂/rGO nanocomposites were used as signal amplification platform for the first time to construct a highly sensitive and label-free electrochemical immunosensor for detection of carcinoembryonic antigen?CEA?.The time-current curve was used to record the electrocatalytic process.The constructed immunosensor achieved ultrasensitive and specific detection of CEA and the detection limit was 1.6 fg/mL.?4?An electrochemical aptasensor based on Au@GS and CoPd NPs was constructed to detect thrombin.Thiol-labeled thrombin capture probe?Apt1?and biotin-labeled thrombin reporting probe?Apt2?were designed to implement the sandwich strategy.CoPd NPs showed good catalytic performance for hydrogen peroxide,and the current response was linear with thrombin concentration.The linear range of thrombin detection was 0.01-2.00 ng/mL,and the detection limit was as low as 5 pg/mL.?5?A sensitive electrochemical aptasensor for the detection of lead ion(Pb²⁺)was designed based on gold-modified graphene nanocomposites with different morphologies.Gold modified porous reduced graphene oxide?Au@p-rGO?was synthesized and used as a carrier for immobilizing Apt1.Gold modified graphene oxide?Au NPs@GO?was used as a signal probe to connect with Apt2.Based on the principle of base complementary pairing,it was immobilized on the electrode.Under the optimum conditions,the linear response range of the prepared electrochemical aptasensor to Pb²⁺was 5 pmol/L to 1?mol/L,with the detection limit of 1.67 pmol/L.?6?An electrochemical aptasensor for the sensitive detection of Pb²⁺was constructed by using gold-modified molybdenum disulfide/reduced graphene oxide?Au@MoS₂/rGO?nanocomposites and gold-palladium?AuPd?modified MIL-88?Fe?metal-organic framework materials?AuPd@Fe-MOFs?.The aptasensor had a linear response to Pb²⁺in the range of 5.0pmol/L to 2.0?mol/L,and the detection limit is 0.07 pmol/L.At the same time,the electrochemical aptasensor exhibited good selectivity,stability and reproducibility,and showed good performance in actual water sample analysis.