The Detection Of Zearalenone Based On Electrochemical Aptasensor

Zearalenone(ZEN)is a kind of mycotoxin that widely pollutes grain and other agricultural products and is easy to remain.It is easy to enter the human body through accumulation,resulting in immunotoxicity,cytotoxicity,reproductive toxicity and estrogen effect,which poses a great threat to human health.Therefore,the establishment of a sensitive and efficient ZEN detection method plays an extremely important role in maintaining food safety and protecting human health.Among the detection methods used at present,the electrochemical method has attracted wide attention due to its short analysis time,low equipment cost,simple fabrication and easy miniaturization.In this paper,aptamers were used to improve the specificity of electrochemical sensors.In order to improve the sensitivity,three novel electrochemical aptasensors were constructed for the detection of ZEN by using a variety of signal amplification strategies such as hybridization chain reaction,enzyme-induced cyclic reaction and nanomaterials.The specific research contents are as follows:1.Using Rec Jf exonuclease-induced cyclic reaction as signal amplification strategy,and using[Fe(CN)₆]^3-/4-as signal probe,a kind of homogeneous electrochemical aptasensor with current-increasing was prepared.In the homogeneous electrochemical sensing strategy,all the target recognition and signal amplification processes take place in the solution,which improves the binding efficiency of aptamer to the targe,and the operation is simple and conducive to improve the detection sensitivity.The experimental parameters were optimized,and the optimal C_Apt:C_S1:C_S2 was 2:1.5:1.5,the optimal amount of Rec Jf exonuclease was 5U,and the optimal incubation time of Rec Jf exonuclease was 90 min.Under the optimal conditions,the reduction peak current shows a linear relationship with lg C_ZEN in the range of5×10^-6 ng/mL?50 ng/mL,and the detection limit is 0.51 fg/mL.The sensor has high specificity,acceptable repeatability,reproducibility and stability.2.In this experiment,two DNA strands,H1 and H2,which are rich in G bases,were designed by taking advantage of the signal probe MB's ability to specifically adsorb G bases and embed double-stranded DNA grooves.They were assembled on the electrode step by step to amplify the signal,and exonuclease III(EXO?)was introduced to reduce the background current.In the absence of ZEN,Exo?can reduce the background current by shear action,and the hybrid chain reaction can not be carried out on the electrode.However,in the presence of ZEN,Exo?can hardly work,and a large amount of MB can be adsorbed on the electrode through the hybrid chain reaction of H1 and H2,resulting in a strong current.The optimization results of the experimental parameters are:the optimal concentration of MB is 8 m M,the optimal incubation time of MB is 30 min,the optimal concentration of c DNA is 2?M,and the optimal amount of EXO?is 8 U.Under optimal conditions,the sensor has a detection limit of 13 fg/mL in the linear range of 5×10^-5 ng/mL?50 ng/mL.Studies have shown that the sensor has strong anti-interference ability to OTA,FB1 and AFB1.The standard method was used to add standard to corn flour and beer samples,and the average recovries was 89.7%?101.2%and 89.3%?99.7%,respectively.3.The single signal probe is easily affected by external conditions such as the instrument and the detection environment,and ratiometric electrochemical sensor can reduce this interference.In this experiment,a dual-signal ratiometric electrochemical aptasensor was designed to detect ZEN with MB and Ag⁺as signal probes.In the presence of ZEN,the current value of MB increases and the current value of Ag⁺decreases.By optimizing the concentration of MB,there was a good linear relationship between I_MB/I_Ag+and lg C_ZEN in the range of 1×10^-5 ng/mL?10 ng/mL,the detection limit was 5 fg/mL,and the correlation coefficient was 0.997.The sensor shows good specificity in the presence of100-fold interference toxins,and the average recovery was 94.8%?105.1%in the sample of labeled corn meal.In addition,the RSD of reproducibility and repeatability experiments are 3.2%and 2.5%respectively,which indicates that the sensor has good repeatability and reproducibility.