Modified Carbon-based Nanomaterial Electrochemical Research On Immunosensors

At present,the quantitative detection of tumor markers has become one of the most important methods for the early diagnosis of cancer.The content of tumor markers can directly reflect the occurrence and changes of tumors.Based on the combination of immunoassay and electrochemical technology,the electrochemical immunosensor has been developed as a biosensor with fast analysis,high selectivity,simple operation and high sensitivity.The construction of sensor-sensitive interfaces is one of the most important and critical steps in today’s research.Carbon nanomaterials have special structures and properties,such as large specific surface area and strong biological affinity,which can be used to construct sensitive interfaces.Based on a variety of carbon-based nanomaterials,this paper builds carbon-based nanocomposites together with precious metals and polymer nanoparticles to explore the application of new electrochemical immunosensors and improve their performance in bioanalytical detection.This article mainly carries out the following work:1.The template free one step pyrolysis method was used to generate porous carbon to provide larger load area.Under constant voltage,Prussian blue（PB）was applied to the porous carbon surface as an electroactive substance to provide detection signals.The alpha fetoprotein antibody（anti-AFP）was immobilized with gold nanoparticles to detect the alpha fetoprotein（AFP）.Under optimal conditions,the detection range is 0.005-50 ng·m L^-1,and the detection limit is 0.002 ng·mL^-1（S/N=3）.2.Based on dicyandiamide as carbon source and hydrothermal synthesis of molybdenum disulfide（MOS₂）together to firing into the multidimensional structure of irregular carbon doping,adopt the chemical oxidative polymerization of polyaniline coating on the structure and will be modified on the electrode surface.Gold nanoparticles could ultimately contribute to the lower polyaniline in neutral environment improvement to modified the electrochemical performance,and for a fixed alpha fetoprotein antibody.Under optimal conditions,the detection range is 0.001-100 ng·m L^-1,and the detection limit is 0.0006 ng·m L^-1（S/N=3）.3.Bimetal core shell structure has high conductivity,high specific surface area and biocompatibility compared with mono metal components.First,we prepared rGO/MWCNTs as providing high conductivity carrier for double core shell structure Au@Pd and Cu@Ag.The affinity interaction of Pd with antibodies holds more antibodies,and Cu@Ag provides electrochemical signals for detection.The designed electrochemical immunosensor showed excellent electrochemical performance after testing.Under the optimized conditions,the detection range was 0.001-50 ng·m L^-1,and the detection limit was 0.0008 ng·m L^-1（S/N=3）.4.Preparation of coral-like polyaniline as an electroactive substance,and the onion-like carbon particles NOLC adsorbed on the surface thereof provide more sites for the stability of the polyaniline.The load of nano gold is used to immobilizing antibodies and improve the electrochemical performance of polyaniline The electrochemical properties were characterized by cyclic voltammetry（CV）,electrochemical impedance spectroscopy（EIS）and other electrochemical test methods.The detection range was 0.001-100 ng·m L^-1 under the optimized conditions,and the detection limit was 0.0008 ng·mL^-1（S/N=3）.