New Analytical Method Based On Graphene And Metal Oxide Nanocomposites For Immunosens Detection

In recent years,immune sensors are widely used in biological macromolecules and organic small molecule detection,ascribe to the characteristics of high selectivity,low price,easy to miniaturization.Graphene and metal oxide nanomaterials are well-suited for building new sensors due to their unique structure and properties.Here,a new photoelectrictrochemical interface based on ZnO nanorod arrays and an immunofluorescent biosensor based on graphene/polymer/iron oxide nanocomposites were constructed,which reduced the non-specificity adsorption of the protein macromolecules and significantly improved the sensitivity.Two kinds of pesticide small molecule artificial antigens and antibodies were designed,the main research content and details are described as follows:1.Anon-labeled photoelectrochemical immunosensor based on zinc oxide nanorod arrays was designed to detect the biomarker of tumuor,nucleoside diphosphate(NDPK-A)protein.The co-sensitized structure formed by the oxidized nanorod array and the cadmium sulfide nanoparticles and manganese ions(ZnO/CdS:Mn2+)significantly improved the photocurrent intensity.The prepared photoelectrodes based on this nanomaterials had significant response behavior for NDPK-A,the photocurrent intensity had a good linearity with the NDPK-A concentration in the range of 0.5 pg/mL to 10[?g/mL with a detection limit of 0.3 pg/mL,high detection sensitivity,good reproducibility,selectivity of the resulting photoelectrochemical biosensor are demonstrated.2.A fluorescence immunosensor based on graphene/polyacrylhydrazide/iron oxide nanocomposite was designed to analylize the genic crop marker protease 5-enol pyruvate-shikimate-3-phosphate synthase(CP4-EPSPS).Polyacrylhydrazide-modified graphene can reduce the non-specific adsorption of protein effectively due to electrostatic repulsion and surface hydrophilicity.The combination of iron oxide nanoparticles improved the fluorescence quenching ability of cadmium telluride quantum dots on labeled antigens(4 times of graphene-based carrier probe).The nanocomposite was used as a carrier probe for nanobodies and a fluorescence immunoassay was performed on CP4-EPSPS by competition method.The method showed multiple advantageshigh like high sensitivity(detection limit of 0.34 ng/mL)and wide linear range(5-100 ng/mL)3.The hapten,artificial antigen and monoclonal antibody of the pesticide small molecule fenthion and chlordecone was designed and obtained.One chlordecone hapten and two fenthion haptens were synthesized and the coupled sites were added onto framework of molecular without the changes in characteristic groups.The hapten was conjugated to the carrier protein to obtain an artificial antigen.Mice were immunized with fenthion and chlordecone artificial antigens,strong immunogenicity of the protein induces the immune response,and the artificial arms could help epitope explosed to B lymphocytes,stimulating and inducing mice to produce high selectivity and high affinity antibody.