Construction Of Electrochemical Biosensor Based On Mo-based Complex Oxide And Carbon-based Composite

Recently,molybdate nanomaterials have attracted extensive attention for their potential applications in electrode materials due to the stable chemical properties,non-toxicity,and good electrical properties among metal composite oxides.Moreover,carbon-based composite obtained via simple thermolysis of metal-organic frameworks?MOFs?have competitive virtues in accordance of layered porosity,controllable morphologies,making them directly as high activity catalysts or supports for various electrochemical sensor.Herein,two types of molybdate nanomaterials and a carbon-based complex were synthesized and used to construct different biosensors.1.CoMoO₄ was prepared by hydrothermal method and was characterized via scanning electron microscope?SEM?,X-rays Diffraction?XRD?and energy dispersive spectroscopy?EDS?.Subsequently,a electrochemical platform based on CoMoO₄ and ionic liquid?[BMIm]BF₄,IL?composite membrane was prepared for the construction of glucose biosensor.The structural information of GOx was investigated by UV-visible?UV-vis?spectroscopy and Fourier transform infrared?FT-IR?spectroscopy.Cyclic Voltammetry?CV?and Electrochemical impedance spectroscopy?EIS?were applied to explore the direct electrochemical behavior of GOx on the GOx/CoMoO₄/IL-CPE modified electrode.In addition,spectroscopic and electrochemical measurements revealed that GOx remained its bioactivity on the surface of CoMoO₄/IL composite film,and had excellent electrocatalytic activity towards glucose in the range of 5-4070?M with a low detection limit of 2.3?M.2.Bi₂MoO₆ nanomaterials was also synthesized by hydrothermal method,and it's morphologies and phases were further characterized by SEM,XRD,and EDS,which confirmed the successful synthesis of Bi₂MoO₆,and its loose structure provides more active sites for the subsequent immobilization of antigen and antibody.Moreover,Bi₂MoO₆ was mixed with IL to prepare a Bi₂MoO₆/IL composite film modified electrode,then the crosslinker?glutaraldehyde,GA?,anti-IgG and blocking agent?bovine serum albumin,BSA?were sequentially modified on Bi₂MoO₆/IL/CPE to obtain BSA/anti-IgG/GA/Bi₂MoO₆/IL-CPE.The electrochemical behavior of human immunoglobulin?IgG?immunosensor was studied by CV and EIS.Furthermore,the analytical performance of this lable-free IgG immunosensor was evaluated under optimum conditions by differential pulse voltammetry?DPV?with a wide linear range(0.01-1000 ng·mL^-1)and a low detection limit(0.004 ng·mL^-1).3.ZnO/porous carbon matrix?ZnO/MPC?was obtained via simple thermolysis of a mixed-ligand MOF?Zn-BDC-TED?and was characterized by SEM and XRD.Subsequently,the ZnO/MPC/IL composite film,cross-linking agent?EDC/NHS?,C-reactive protein antibody?anti-CRP?,and BSA were modified on the CPE in sequence to get BSA/anti-CRP/ZnO/MPC/IL-CPE.The stepwise assembly process of the CRP immunosensor was monitored by electrochemical measurements including CV and EIS.After the parameter optimization,the DPV response decreased linearly with the logarithm of CRP levels in an extensive range of 0.01-1000 ng·mL^-1,and the detection limit was as low as 5.0 pg·mL^-1.Meanwhile,the lable-free immunosensor also showed excellent selectivity,reproducibility and stability.It shows that ZnO/MPC composite and many carbon-based composite obtained through thermolysis of MOFs will be a prospective platform for medical diagnostic analysis.