| Recently,food safety incidents occur frequently.Organophosphorus pesticides(OPs)residues and mycotoxin contamination are the two most serious security risks.OPs have been widely used in modern agricultural production due to their high insecticidal efficiency.However,some unreasonable use of OPs has caused excessive pesticide residues in crops and brought serious food safety and environmental pollution hazards.Mycotoxins are a class of secondary metabolites produced by fungi growing in crops.When humans and animals eat food contaminated with mycotoxins,there is a risk of carcinogenesis and teratogenesis.The United Nations data shows that a quarter of the world’s grain and oil products are polluted by mycotoxins to varying degrees every year,causing heavy economic losses and potential safety hazards.Particularly,the condition of excessive mycotoxins in infant and young children’s food has aroused intensive concern in society.Due to the particularity of the consumer,the safety standard of infant and young children’s food are more stringent.Therefore,it is of great practical significance to explore sensitive,accurate and efficient detection techniques for mycotoxin and organophosphorus pesticides.Based on the fluorescence methods,this paper realizes the sensitive detection of chlorpyrifos and four mycotoxins,including the following two parts:(1)Based on the fluorescence reaction triggered by alkaline phosphatase(ALP)and enzyme inhibition mechanism,a fluorescence sensor was constructed to realize the sensitive detection of chlorpyrifos.In this work,ALP could catalyze the dephosphorylation of the substrate L-ascorbic acid 2-phosphate sesquimagnesium hydrate(AAP)to produce ascorbic acid(AA).Then AA could react with o-phenylenediamine(OPD)to form a new substance containing quinoxaline fluorophore,so the solution had distinct fluorescence signal at 425 nm.When chlorpyrifos was added,the activity of ALP was inhibited obviously.Therefore,the concentration of fluorescent substance reduced,and the fluorescence intensity of the solution declined.The detection range for chlorpyrifos was 20 pg/m L-1000 ng/m L,with a detection limit of 15.03 pg/m L(S/N = 3).This strategy had excellent accuracy and had been applied to detect chlorpyrifos in vegetable samples.In addition,this method did not require any cumbersome fluorescent labeling step,and could realize qualitative judgment by the color of the solution under ultraviolet light.(2)A solid-phase immunochip was constructed to realize the simultaneous detection of aflatoxin B1,aflatoxin M1,zearalenone,fumonisin B1(AFB1,AFM1,ZEN,FB1).Quantum dot-antigen conjugate(Ag-BSA-QD)was prepared by labeling the complete antigen(Ag-BSA)of mycotoxins with quantum dots(QDs).Use nitrocellulose membrane(NC membrane)as the substrate and fix the monoclonal antibodies of four mycotoxins on its surface.Then add the mixture of mycotoxin standard solution and the corresponding Ag-BSA-QD to form a direct competition mode.Through the specific immune reaction between antigen and antibody,the solid-phase chip could capture quantum dots.Then the fluorescence signal of each detection hole was collected by the microfluidic chip analyzer to achieve the purpose of high-throughput simultaneous detection.This immunochip detection method was sensitive and efficient,and could accurately determine 32 samples within 1 minute.The linear ranges of detection for AFB1,AFM1,ZEN,and FB1 were 0.01-10 ng/m L,0.1-100 ng/m L,1-200 ng/m L and 10-500 ng/m L respectively.This method had been preliminarily applied to the detection of infant milk powder samples.Compared with other mycotoxin detection methods,the proposed solid-phase chip method was more efficient and simple,and could complete the detection by only one step of immune response.Besides,this strategy provided new research ideas for the detection of other harmful substances in food(such as agricultural and veterinary drugs,hormones,etc.). |
PDF Full Text Request