| Covalent organic framework(COF) is a new type of crystalline porous material with stable structure. It also has open channels, larger surface area, excellent conductivity, special functional groups, and easy modification with all types of functional molecules or proteins. In this work, we synthesized covalent organic framework(COF) material, and Pd, Pt, Au-coordinated COF, M/COF-LZU1 composite material was accordingly synthesized. Then, it was modified on the surface of GCE as an electrochemical sensor platform. Au/microspheres(CMS), Pt/Ru/C and Au/Cu-MOF nanocomposite were also synthesized and used as the label of secondary anti-C-reactive protein(CRP)antibody for constructing CRP immunosensor. The details are summarized as follows:(1) a new imine-linked covalent organic framework(COF) material was synthesized using organic monomer via solvothermal methods. Pt-coordinated COF,Pt/COF-LZU1, was accordingly synthesized through simple post-treatment at ambient conditions, which showed excellent catalytic activity. It was mixed with Nafion to prepare Pt/COF-LZU1/ Nafion electrochemical sensors for the determination of bisphenol A. Under the optimal experimental conditions, differential pulse voltammetry(DPV) were employed to detect bisphenol A. The oxidation peak current response of the electrochemical sensor has a linear relationship with the concentration of BPA ranging from 0.25μg/mL to 100μg /mL with a detection limit of0.08μg/mL. The sensor provides a new simple method for the determination of BPA.(2) Utilizing the combination ability between Pd(Ⅱ) and imine of COF-LZU1,Pd/COF-LZU1 porous composite material was synthesized. Then, a label-free C-reactive protein immunosensorusing was constructed using the Pd/COF-LZUI porous composite material to immobilize anti-CRP on the surface of GCE. When anti-CRP binds with CRP antigen, the formed immuno complex obstruct the electric signal of Fe(CN)64-/3-, which can be used to realize label-free detection of CRP.Electrochemical impedence spectroscopy(EIS) and differential pulse voltammetry(DPV) were employed to characterize the immunosensor. Under the optimal experimental conditions, the method of DPV were employed to detect CRP. The linear range was 5 ~ 180 ng/ mL. The detection limit is 1.66 ng/mL with the linear correlation coefficient of 0.992. This immunosensor provides a novel and simple way to detect the CRP, and develops the application of the COFs in the electrochemical immunosensor.(3) Carbon microspheres(CMS) was synthesized by hydrothermal method,and followed adsorbing PDDA and Au. Au/CMS nanocomposite was synthesized with electrostatic interaction, which has good catalytic properties to the oxidation of ascorbic acid. A sandwich-type C-reactive protein immunosensor based on the palladium-coordinated covalent organic frameworks(Pd/COF-LZU1) material and Au/CMS nanocomposite as label was prepared. The immunosensor exhibited good stability and sensitivity for the simultaneous determination of CRP with linear ranges of 0.25–150 ng/ mL. The detection limit is 0.08 ng/mL with the linear correlation coefficient of 0.998.(4) Pt/Ru/C nanocomposite was synthesized by microwave method, which has good catalytic properties to the reduction of hydrogen peroxide. In order to replace enzyme-label, Pt/Ru/C nanocomposite was used as label of secondary anti-CRP antibody to detect CRP. Under the optimal experimental conditions,chronoamperometry(i-t) was utilized to test the concentration of CRP. The linear range covers from 0.5 ng/mL to 150 ng/mL, with the detection limit of 0.17 ng/mL.(5) Gold nanoparticles were loaded on the Cu(Ⅱ)-HKUST-1 to form Au/Cu(Ⅱ)-HKUST-1 nanocomposite materials at ambient conditions, which was used as the label of secondary anti-CRP antibody for fabricating sandwich immunosensor.Cooper ion could be detected directly by differential pulse voltammetry(DPV), the current signal is proportioned to the concentration of CRP ranging from 1 ng/mL to400 ng/mL with the detection limit was 0.33 ng/mL.
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