Electrochemical Immunosensor Based On Functionalized Phenolic Resin Microporous Carbon Spheres For Dection Of Tumor Markers

Tumor is one of the most serious diseases threatening human health and life.The incidence of malignant tumor is closely related to the content of specific tumor markers in the body.Quantitative detection of tumor markers plays an important role in basic medical research and clinical diagnosis.Eelectrochemical immunoassay has attracted the interest of analysts because of its advantages such as low detection cost,short time consumption,simple preparation and convenient operation.In this paper,we used functionalized phenolic resin microporous carbon spheres with excellent electrochemical properties to enhance the detection signal,and applied it for the construction of electrochemical immunesensor,improving the sensitivity of the sensor.The main research contents and results are as follows:（1）Electrochemical immunosensor based on Au@Ag/PDA-PR-MCS was developed for the sensitive detection of AFPA novel signal amplification label using Au@Ag nanoparticles loaded by polydopamine functionalized phenolic resin microporous carbon spheres（Au@Ag/PDA-PR-MCS）.PR-MCS have homogeneous particle size and a hign surface area.PDA functionalized phenolic resin microporous carbon spheres（PDA-PR-MCS）with the advantages of PR-MCS and have strong adsorption ability.With the unique structure of PDA-PR-MCS,it not only improved the loading capacity and dispersity of Au@Ag,but also enhances the stability for the combination of the Au@Ag by chemical absorption via Au@Ag and-NH₂.The composite has special electrocatalytic activity towards reduction of hydrogen peroxide（H₂O₂）,which makes the electrochemical response more sensitive.Au NPs with good biocompatibility and conductivity were electrodeposited on the surface of electrode used as a sensing platform immobilizing primary antibody（Ab₁）and accelerating the electron transfer on the electrode interface.Under optimal experimental conditions,the developed immunosensor showed a broad linear range（20fg/m L-100 ng/m L）for alpha fetoprotein（AFP）detection and a low detection limit（6.7 fg/m L）.Moreover,the good detection performance of human serum samples indicated that the designed immunosensor will provide a new method in clinical detection of AFP.（2）Electrochemical immunosensor based on Pd@Ag@Ce O₂ was developed for the sensitive detection of AFPPd@Ag@CeO₂ core@shell nanoparticles（NPs）was prepared and used as signal amplified label to design electrochemical immunosensor for quantitative detection ofα-fetoprotein（AFP）.The Pd@Ag@Ce O₂ accelerated electron transfer of the sensing interface as well as increased the number of secondary antibodies（Ab₂）owing to good conductivity and the large surface area.Particularly,Ce O₂as a shell layer,can effectively avoid the aggregation of Pd@Ag,thus making the composite material have high stability and the excellent analytical performance of the immunesensor.Furthermore,Au NPs supported microporous carbon spheres functionalized by 3-aminopropyltriethoxysilane（Au-APTES-MCS）was used to immobilize the primary antibodies（Ab₁）,owing to good electrical conductivity and favorable biocompatibility.The developed immunosensor showed a linear ranging from 0.4 pg/m L to100 ng/m L and a detection limit of 0.13 pg/m L.Meanwhile,it exhibited good reproducibility,high specificity,and long-term stability,which revealed that the designed immunosensor had potential application in clinical analysis.（3）Electrochemical immunosensor based on CDs-3D-PG-Pd@Au NCs was developed for the sensitive detection of c Tn IPd@Au nanocubes supportedβ-cyclodextrins functionalized three-dimensional porous graphene（CDs-3D-PG-Pd@Au NCs）was synthesized.β-cyclodextrins（CDs）could improve hydrophilic property of three-dimensional porous graphene（3D-PG）and have good capture capability to the secondary antibody（Ab₂）.The large number of Pd@Au NCs could be loaded on the CDs-3D-PG to improve electrochemical signal.The obtained CDs-3D-PG-Pd@Au NCs composite was used as signal amplification label.Au nanoparticles（Au NPs）and thionine（Th）loaded on the amino-functionalized microporous carbon sphere（Au NPs-FMCS-Th）as sensor platform,which not only immobilized primary antibody（Ab₁）through the interaction of Au-NH₂,but also increased the electron transfer rate of electrode surface with mediated effect of Th,thus further amplifying signal response.Cyclic voltammetry（CV）and amperometric i-t methods were used to study the electrocatalytic reduction of H₂O₂ by CDs-3D-PG-Pd@Au NCs with electron mediation of Th.Under optimal conditions,the designed cardiac troponin I（c Tn I）immunosensor showed high selectivity,long-term stability and good reproducibility with a low detection limit of 33.3 fg/m L.Satisfactory results were gained for detection of real serum samples,suggesting the designed method could provide an effective strategy in clinical research.