Fabrication Of Electrochemical Sensors For Determining Mycotoxins And Its Applications

Mycotoxins refer to toxic fungi-producing secondary metabolites,its pollution is widespread all over the world which cause both public health and economic risk.Therefore,it is vitally important for the development of a fast,sensitive,specific,and reliable method for the detection of mycotoxins.In this study,an electrochemical nanosensor for the rapid determination of zearalenone(ZEA)was established firstly.Then,we developed an electrochemical immunosensor for the quantitatively determination of the non-conductive DON molecule by redox reactions of probe solution.Finally,a molecularly imprinted sensor contain antibody-like molecular recognition was proposed,providing a new strategy for food safety detection.Mainly research works is as follows:(1)Copper-based metal-organic framework/magnetic Fe₃O₄-graphene oxide nanohybrid sensor for ZEA's electrochemical detection:An electrochemical sensor was proposed by a nanocomposite modified electrode combining copper-based metal-organic framework(Cu-MOF)and magnetic Fe₃O₄-graphene oxide(Fe₃O₄-GO)for the quantitative determination of zearalenone(ZEA).Under the optimal conditions,the crafted sensor has large surface area,high-quality electron transport capacity,distinguished selectivity,acceptable repeatability and reproducibility for ZEA detection.Moreover,the sensor exhibited a linear relationship in the range of 9.55?2865.24 ng m L^-1 with the limit of detection of 8.11 ng m L^-1under the optimal conditions.The noteworthy applicability of the sensor was successfully employed for the analysis of ZEA in spiked cereal samples with the recovery ranged from 93.3%to 115.8%and the relative standard deviation less than 5%demonstrating that this strategy can provide methodological support for the analysis and detection of ZEA in grain products.(2)Determination of DON by electrochemical immunosensor:Simultaneous ultrasonically treated of chlorauric acid,black phosphorus(BP)and carboxylated multi-walled carbon nanotubes(COOH-MWCNTs)to obtain BP-Au-COOH-MWCNTs,A novel electrochemical immunosensor based on BP-Au-COOH-MWCNTs was employed for determination of deoxynivalenol(DON).Scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS)and electrochemical methods were used to characterize the prepared BP-Au-COOH-MWCNTs/GCE,the results showed that the prepared Au-COOH-MWCNTs/GCE had large effective surface area and electrical conductivity.With[Fe(CN)₆]^3-/4-/PBS as probe solution,the proposed electrochemical immunosensor show a good linear relationship in the linear range of 2 pg/m L?80 ng/m L,and the LOD was 0.495 pg/m L.In addition,the recoveries of spiked wheat flour samples by the immunosensor shows that the sensor has great application potential in the determination of DON in wheat flour.(3)A highly-sensitive and selective antibody-like sensor based on molecularly imprinted poly(L-arginine)on COOH-MWCNTs for electrochemical recognition and detection of deoxynivalenol:A new strategy to mimic antibody for electrochemical recognition and detection of DON using a highly-sensitive and selective antibody-like sensor based on molecularly imprinted poly(L-arginine)(P-Arg-MIP)on carboxylic acid functionalized carbon nanotubes(COOH-MWCNTs)was proposed.L-arginine as functional monomer was screened to prepare imprinted electrode via its electro-polymerization in the presence of DON onto the surface of COOH-MWCNTs electrode coupled with theoretical calculation.P-Arg-MIP/COOH-MWCNTs were characterized by SEM,EDS,Fourier transform infrared spectroscopy(FTIR),and cyclic voltammetry(CV),respectively.P-Arg-MIP/COOH-MWCNTs displayed relatively high conductivity,high effective surface area,antibody-like molecular recognition and affinity,and a good response towards DON in a linear range from 0.1 to 70?M with LOD of 0.07?M in wheat flour samples with satisfactory recovery.