The Preparation Of Transition Metal Sulfide Nanocomposites And Its Application In Sensing Analysis

Accompanied by the economic boom around the world,the life quality of the people has been significantly improved,and more attention has been paid to the early prevention of diseases,especially tumors.Changes in the concentration of tumor marker can be used to understand the status of tumor tissue and provide the guidance for diagnosis,treatment,and prognosis of the tumor.In recent years,the electrochemical immunosensor based on the specific binding of antigen and antibody has attracted extensive attention due to its high sensitivity,high specificity,and easy miniaturization.The transition metal sulfide with metallic properties and semiconductivity has a large specific surface area,tunable band-gap,and excellent catalytic performance,which is widely used in the field of electrocatalysis.In this paper,various signal amplification strategies are established based on different forms of molybdenum sulfide nanomaterials to achieve sensitive determination of the tumor marker.（1）A sensitive sandwich-type electrochemical immunosensor for the determination of hepatitis B e antigen（HBe Ag）was successfully fabricated,based on the molybdenum disulfide doped multiwalled carbon nanotubes functionalized by gold@palladium nanoparticles（Au@Pd/Mo S₂@MWCNTs）.The synthetic nanocomposites not only had a high specific surface area and good biocompatibility but also demonstrated excellent electro-catalytical property.Au NPs functionalized porous reduced graphene oxide（p-r GO@Au NPs）were used as the sensing platforms and primary antibodies carriers,which can accelerate the electron transfer and promote the load capacity of primary antibodies（Ab₁）,enhancing the sensitivity of the proposed immunosensor.Under optimal conditions,the developed immunosensor could achieve a good result for HBe Ag detection with a low detection limit of 26 fg/m L.（2）A novel electrochemical label-free immunosensor fabricated by Pd nanoparticles functionalized three-dimensional wrinkly amorphous Mo S_x composites（Pd NPs@3D Mo S_x）was developed for the determination of insulin antigen.After 3D Mo S_x composites were modified in the presence of hexadecyl trimethyl ammonium bromide（CTAB）,Pd NPs@3D Mo S_x were prepared by in-situ reduction method,which possessed an excellent catalytic activity for the reduction of H₂O₂.Furthermore,Pd NPs@3D Mo S_x composites with favorable biological compatibility can bind with a great many antibodies to capture insulin antigen.Attributed to the excellent property,electrochemical signals could be greatly amplified,contributing to improving detection sensitivity.The proposed immunosensor exhibited a sensitively linear relation with a low detection limit of 3.0pg/m L.（3）A novel ultrasensitive sandwich-type electrochemical immunosensor was proposed to determine the biomarker of diabetes-insulin antigen.Molybdenum disulfide nanosheets loaded gold nanoparticles（Mo S₂/Au NPs）,served as the substrate,to functionalize bare glassy carbon electrodes（GCE）.The Mo S₂/Au NPs not only exhibited superior biocompatible and large specific surface area to enhance the loading capacity of primary antibody（Ab₁）but also exhibited good electrical conductivity to accelerate electron transfer rate.Moreover,the amino groups functionalized cuprous oxide@titanium dioxide octahedron（Cu₂O@Ti O₂-NH₂）were prepared to load dendritic platinum-copper nanoparticles（Pt Cu NPs）to achieve signal amplification strategy.The resultant nanocomposites effectively enhanced the catalytically active sites and specific surface area,even improve conductivity.Besides,the resultant nanocomposites exhibited superior electrocatalytic activity towards the reduction of hydrogen peroxide（H₂O₂）,achieving the signal amplification.The proposed immunosensor achieved a linear relationship between the logarithm of insulin antigen concentration and amperometric response,and the limit detection was 0.024 pg/mL.