Nanoenzyme Electrochemical Immunosensing For The Detection Of Deoxynivalenol

Deoxynivalenol(DON)is a major risk factor for food safety,which is widely distributed and difficult to destroy at high temperatures,causing a negative impact on human health and public health.Therefore,improving detection technology to achieve timely monitoring of DON pollution is crucial for ensuring food safety.However,traditional detection methods have various limitations,such as low sensitivity,high cost,cumbersome steps,high equipment costs,and difficulty in miniaturization.Therefore,establishing an analytical platform with high sensitivity,good specificity,simple and fast operation,and low cost for the detection of DON in food is of great significance.In this thesis,we prepared nanoenzymes with efficient electrocatalytic performance,good stability,biocompatibility and high modifiability,and used the peroxidase-like activity of the nanoenzymes to obtain catalytic signals,which were combined with label-free electrochemical immunosensor to establish a highly selective and sensitive trace detection method.The main research work has been carried out in the following areas.(1)A Ni-Fe bimetallic Prussian blue analogue(Ni-Fe PBA)nanoenzyme with high peroxidase-like catalytic activity was synthesized by a simple and environmentally friendly chemical precipitation method.The abundant valence polyanions in Ni-Fe bimetallic can effectively promote the reaction of the catalytic active site,thus improving the electrochemical analysis performance.Using chitosan as a carrier matrix for physisorption of DON antibodies,the quantitative detection of DON using electrocatalytic signal changes generated by the active sites of Ni-Fe PBA and thionine molecules.As a label-free electrochemical immunosensor for DON,Ni-Fe PBA exhibited excellent sensing performance with a detection limit as low as 4.5 pg mL-1(S/N=3)and a detection range of 10-107 pg mL-1.In the detection of actual samples,the recoveries ranged from 94.0%to 106.7%with the relative standard deviations of 2.2%-4.6%,indicating that the sensor was successfully applied to the accurate detection of DON in food.(2)The porous electrochemical nanomaterial Calcined-PA-NH2-MIL-101(CPNM)with abundant amino acid modifications was synthesized using a palmitic acid(PA)pre-linking and amino acid functionalization scheme.PA induced defect generation,formed highly stable porous structures,increased catalytic active sites,and promoted biomolecular modifications,thus improving electrochemical analytical performance.In addition,the introduction of NH2 groups promoted the covalent immobilization of DON antibodies.Finally,the feasibility of CPNM as a DON sensing nanomaterial was investigated using cyclic voltammetry as well as mechanistic analysis,and the proposed electrochemical immunosensor achieved wide detection range from 10 to 107 pg mL-1 under optimized conditions,with a detection limit of 9.6 pg mL-1(S/N=3).In addition,in actual sample experiments,the recovery rate is 90.7%-105.3%,and the relative standard deviation is 2.6%-4.2%,indicating that the sensor can accurately and effectively detect DON in food.(3)A mesh-like gel structure was prepared using cross-linked polymerization to achieve uniform loading of PMo12 and the three-dimensional(3D)nanoparticles Mo2C were obtained after carbonization.Besides the size of the Mo2C particles was regulated by adjusting the amount of PMo12 used to form high specific surface area.This facilitated the generation of more catalytic sites as well as modification sites,resulting in higher peroxidase-like catalytic activity.The subsequent loading of the conducting polymer polyethyleneimine(PEI)not only accelerates the electron transfer process and the catalytic reaction,but also the amino functionalization of PEI makes PEI@Small-Mo2C a good carrier for the covalent immobilization of DON antibodies,which promotes biomolecular modifications and improves the electrochemical analysis performance.The label-free electrochemical immunosensing was constructed based on PEI@Small-Mo2C nanoenzyme,and the quantitative detection of DON in food was achieved by electrocatalytic signal generated by PEI@Small-Mo2C active sites and thionine molecules.The linear range obtained is 10-1-107 pg mL-1,with a detection limit of 6.1×10-2 pg mL-1(S/N=3).Finally,the sensor was used for the detection of DON in actual spiked samples and satisfactory recoveries(89.3%-110.0%)were obtained.