Application Of Nano-mimic Enzyme And Metal-organic Gels In Biosensor And Synthesis And Properties Of Organic Electro-optic Materials

Metal organic framework materials（MOFs）and metal gels（MOGs）have broad application prospects in biosensors due to their inherent porous structure,high specific surface area and pore tunability.In this paper,Fe-MOG and Mn-MOF-74,which have simulated enzyme properties,and Cu-MOF（HKUST-I）were synthesized and used to construct biosensors for detection of disease markers and toxin in food.In addition,organic electro-optic materials with good electro-optic properties have been synthesized.The work of this paper is divided into the following four parts:（1）A novel sandwich immunosensor based on toluidine blue（Tb）loaded metal organic framework（Cu（II）-HKUST-1/Tb）as signal elements and nitrogen-doped 3D carbon nanostructure as electrode substrates was constructed for the detection of C-reaction protein（CRP）.Tb as an electrochemically active agent usually form a polymer by aggregation in the solvent,causing the poor electrochemical response.Therefore,in order to overcome this obstacle,Cu（II）-HKUST-1 with porous nanostructure and large specific surface area was used as the carrier,and a large amount of Tb was loaded to improve its electrochemical performance.In addition,the high electron transfer efficiency of nitrogen-doped bamboo carbon nanotubes improves the sensitivity of biosensors.The current response signal was detected by differential pulse voltammetry（DPV）,and the current response increased with the increase of CRP concentration from 0.5 to 200 ng m L^-1,the limit of detection is 166.7 pg ml^-1（S/N=3）.This biosensor can be applied to the detection of real serum samples,so it has potential application prospects in the field of biomedical detection.A label free electrochemical aptamer sensor based on nano composite material and screen printed electrode was constructed for the detection of ochratoxin（OTA）.With the simulated enzyme characteristic that Pt NPs@Mn-MOF-74 catalyzes H₂O₂reduction to generate current response,it’s used as electrode substrate to capture OTA aptamer chain,and catalyze to generate current response signal.The introduction of small molecules OTA will obturate portion of nanozyme catalytic active site,thus results in the decrease of current signal.In the range of 0.01～300 ng m L^-1,with the increase of OTA concentration,response current values decrease gradually.Utilizing chronoamperometry to detect current response signal can realize the quantitative detection of OTA indirectly.This biosensor has high sensitivity,good reproducibility,and low detection limit of 3.33 pg m L^-1（S/N=3）.It has potential application prospects in the field of mycotoxin detection.（3）A visual magnetic separation biosensor based on the carboxylated magnetic separation platform,using metal ferric ion gel（Fe-MOG）loaded platinum nanoparticles（Pt NPs）as the signal marker,was constructed for the detection of fumarin（FB₁）.The Fe-MOG formed by coordination polymerization has the dual characteristics of metal organic framework（MOFs）and gel.Because of its inherent porous structure and abundant Fe³⁺metal active centers,it has the property of mimetic enzyme,and can oxidize 3,3’,5,5’,-tetramethylbenzidine（TMB）from colorless to blue in the presence of H₂O₂.At the same time,it also can be used as a catalyst carrier to load Pt NPs with good catalytic performance,which can further amply signal and improve the detection sensitivity of biosensor.Uv-vis spectrophotometer was used to detect the change of absorbance at 650 nm.The absorbance value decreased with the increase of FB₁concentration in the range of0.01-2000 ng m L^-1.A signal off small visual biosensor can be constructed and used for detection of FB₁with the detection limit of 3.33 pg m L^-1（S/N=3）.The detection limit of this biosensor is three orders of magnitude lower than that of the commercial ELISA kit.（4）On the basis of electron donor bis（N,N-diethyl）aniline derivatives and electron acceptor TCF,the properties of organic electro-optic materials were improved by introducing different isolation groups on the chromophore molecular structure bridge.Because the double donor and TCF acceptor in the molecular structure have good electron donating and electron absorbing ability respectively,and the isolation group introduced in the electron bridge can effectively weaken the electrostatic interaction between molecules,the organic electro-optic materials with superior performance are obtained.