Research On Electrochemical Detection Of Mycotoxins In Food

Mycotoxins,a group of toxic secondary metabolites produced by fungi in the process of growth,lead to serious food pollution.And mycotoxins have become one of the main factors threatening global food safety.Mycotoxins not only directly contaminate cereal agricultural products,such as corn,wheat,barley,peanuts,oats,rice and feed,but also indirectly contaminate animal food through the food chain,such as milk,meat and eggs.Contaminated food not only has great discount in nutrition,but also brings huge threats to the health and life of human as well as animals.Therefore,developing simple,efficient,accurate and reliable detection methods for mycotoxins is an important way to prevent and solve food contamination problems.Taking the advantages of electrochemiluminescence(ECL)technique,including high sensitivity,high accuracy,simple equipment and fast analysis speed,researchers have developed a variety of sensors for rapid analysis and sensitive determination of mycotoxins.In this paper,a novel ECL aptasensor was constructed to detect ochratoxin A(OTA)with high sensitivity and accuracy.The main contents of this paper are summarized as follows:A simple and sensitive ECL aptasensor was constructed for determination of OTA by taking the advantages of DNA walking machine.As an artificial and convenient signal amplification technique,DNA walking machine improves the detection sensitivity by designing several specific DNA chains and utilizing the directional autonomous motion of the DNA walking chain(DNA walker).As ECL signal emitters,cadmium sulfide quantum dots(CdS QDs)were modified on the surface of electrode through physical adsorption.Originally,the ECL signal of CdS QDs was quenched because of the efficient quenching effect of Cy5-labeled DNA(Cy5-DNA)on CdS QDs.After addition of OTA,the DNA walker autonomously hybridized with Cy5-DNA,making Cy5-DNA be cleaved and released from the electrode surface with the help of endonuclease.Since DNA walker repeatedly hybridized with Cy5-DNA on the electrode surface,plenty of Cy5-DNA were cleaved and stay away from the electrode surface.As a result,the ECL signal of CdS QDs recovered significantly.Therefore,the quantitative determination of OTA concentration was achieved by monitoring the ECL signal after recovery.Under optimal conditions,the aptasensor not only detected OTA in a linear range from 0.05 nM to 5 nM with a detection limit of 12 pM(S/N=3),but also showed an excellent selectivity for OTA over other mycotoxins.More importantly,the aptasensor has been successfully applied to the analysis of OTA in wine and beer,which is of great significance to prevent and solve food contamination problems.