Electrochemical Sensor For Detection Of Aflatoxin B1 In Cereals

Aflatoxin B1(AFB1)is often found in spoilage grains or grain-based foods.When AFB1 is intaked in the human body,it may cause the damage of the immune system,in the serious cases,it can induce cancer.At present,the conventional detection methods of AFBI include thin layer chromatography,high performance liquid chromatography,liquid chromatography-tandem mass spectrometry.These methods have complicated operation,high detection cost,professional training requipment withouton-site detection.Therefore,it is urgent to develop a new detection method with low cost,simple operation,strong stability and suitable for on-site detection to effectively monitor the level of AFB1 at different stages of food production.In this paper,two novel,simple,fast and sensitive electrochemical sensors had been developed for the trace detection of AFB I in cereals.Based on the principle of specific binding of AFB1 and its aptamer,an aptamer-based electrochemical sensor was designed.Mesoporous carbon(CMK)was modified on the surface of the glassy carbon electrode(GCE)to increase the surface area of the electrode.And then gold nanoparticles(AuNPs)were deposited at a constant potential on the surface of the working electrode to improve the electrical signal and provide the available site of the sulfhydryl-modified aptamers in the next step.Nextly,after the corresponding aptamer were connected to the surface of the electrode,methylene blue(MB)was firstly adsorbed on the aptamer chain to cause changes in electrical signals.During the detection process,AFB1 could specifically bind the aptamers and competitively remove MB,which cause the changes in the electrical signals to realize the quantitative detection of AFB1..After the optimal conditions,the linear response range to AFB 1 was 0.1-75 μg·L-1,and the detection limit was as low as 3.6×10-2μg·L-1.In the spiked recovery experiment of different grains(rice,corn,glutinous rice),the recovery rate was between 92.3 and 103.6%.The experiment was verified by high performance liquid chromatography,and the consistent detection results were obtained.Based on the specific bind of the polypeptide and AFB1,an electrochemical sensor was constructed using the polypeptide as a recognition element for the detection of AFB1 which was obtained by computer-aided simulation technology.Firstly,the gold nanoparticles(AuNPs)and copper nanoparticles(CuNPs)were electrodeposited on the surface of the electrode.And then CuNPs was removed by etching with H2SO4 to leave the AuNPs with a multi-layered and multi-branched state.After the sulfhydryl-modified polypeptide was assembled to the surface of the working electrode,AFB1 could specifically bind to the polypeptide during the detection process,which hinder the transfer of electrons and cause an electrical signal change.The linearly range was form 0.01 to 20μg·L-1.Under the optimal conditions,the detection limit was up to 9.4×10-4 μg·L-1.In the spiked recovery experiment of different grains(rice,com,glutinous rice),the recovery rate was between 88.4 and 102.0%.The experiment results were verified by ELISA kit with good consistance which proved the accuracy and reliability.