Portable Electrochemical Immunosensor For Rapid Detection Of Zearalenone In Feed

During the rainy season in southern my country,the temperature is high and the humidity is high,and the feed is mildewed and deteriorated due to mold growth,resulting in a decrease in nutritional value,waste of resources,and major economic losses to feed and breeding enterprises.Along with economic losses,it also endangers the healthy production of livestock and poultry,which leads to safety issues that livestock and poultry products are closely related to people’s health and even life.Zearalenone（ZEN）is a common and highly contaminated mycotoxin in moldy feed produced by Fusarium spp.Serious problems such as false estrus,difficult breeding,miscarriage and stillbirth will occur when livestock and poultry eat ZEN-contaminated feed.In addition to this,it has immunosuppressive,genotoxic,hepatotoxic and neurotoxic effects.Therefore,it is urgent to establish a new method for sensitive and rapid detection of ZEN.Immunosensors have the advantages of rapidity,portability,and strong specificity,and are the main content of this research to develop a portable,rapid and sensitive detection method for ZEN.In this study,three electrochemical immunosensors were established,and the sensing performance,electrochemical properties and stability were compared to provide data support for the establishment of ZEN fast and highly sensitive electrochemical immunoassays for feed and crops.The main research contents and results are as follows:1.Based on Ab₂-Au NRs-Thi-α-CD signal marker,a current-type electrochemical immunosensor was constructed for sensitive detection of ZEN.Subsequently,the morphology,structure,current signal and biocompatibility of the composite electrode were studied.The results show that Cys/Au NPs/WS₂-MWCNT/GCE have excellent electrical conductivity and biocompatibility.In addition,complexes prepared by gold nanorods（Au NRs）,thionine（Thi）,α-cyclodextrin and ZEN antibodies were used as signal labeling probes to modify the hit surface successfully through sandwich immune mode.Under the optimal experimental conditions,the linear range was 0.01 ng m L^-1-100 ng m L^-1 and the detection limit was 0.003 ng m L^-1.The sensor was successfully used for electrochemical immunoassay of ZEN in corn and wheat samples,showing good feasibility and practicability.2.Design and development of a simple portable immunosensor based on poly（aminamine）dendrimer（PD）-multi-walled carbon nanotubes（MWCNT）nanocomposite containing carboxymethyl cellulose（CMC）.Rapid electrochemical immunoassay of ZEN residues in feed ingredients and agricultural foods was performed using a usb disk potentiostat with smart phone.Due to the rich carboxyl groups in PD,MWCNT and CMC,a large number of ZEN monoclonal antibodies were covalent immobilized on the electrode surface of the nanocomposites.A simple and portable USB disk electrochemical immunosensor was fabricated using a smart phone using nano-composite modified screen printing electrode.The linear range of the immunosensor is 0.001-100 ng m L^-1,and the low detection limit is 0.15 pgm L^-1under optimal conditions,which is consistent with the results of the immunosensor prepared with glassy carbon electrode on the traditional potentiostat of desktop computer.Based on the excellent performance of the proposed immunosensor,it is considered to be a simple and rapid analytical method for the detection of ZEN and other harmful substances in feed components and agricultural foods.3.An electrochemical immunosensing electrode（BSA/anti-ZEN/CGQDs/MoS₂-α-CD/GCE）was developed for rapid detection of ZEN by layer modification of two-dimensional MoS₂,α-CD and carboxyl fossil graphite quantum dots（CGQDs）.Polyamine-amine dendritic polymer（PAMAM）toluidine blue（TB）and gold nanoparticles（Au NPs）were combined with ZEN antibody to prepare antibody signal marker（Ab₂-PAMAM-TB-Au NPs）to amplify electrochemical signal.A portable electrochemical immune sensor based on U disk was made by combining disposable screen printing electrode and smart phone.The U disk portable electrochemical sensor has the advantages of simple preparation,small size,high stability,good repeatability and low cost.At the same time,enzyme linked immunoassay（Elisa）was used to establish the linear relationship between ZEN detection,the detection range was 0.3 ng m L^-1 to 24.3 ng m L^-1.The comparison and analysis of the detection results of the two methods showed that the electrochemical sensor obtained a lower detection limit,and the higher ELISA method was more sensitive and simpler to operate,with lower cost.Finally,maize and wheat were added for recovery and detection of ZEN,and the recovery rates were in the range of 97.28%-103.53%,indicating that the electrochemical immunosensor constructed according to the research scheme can effectively detect ZEN and has good development potential in practical application.