Electrochemical Biosensor For The Detection Of Aflatoxin B₁ And Ochratoxin A

Our country is rich in agricultural products and food tradition is mainly based on grain, while a large number of agricultural products are often polluted by a variety of mycotoxins, especially aflatoxin B1(AFB1) and ochratoxin A(OTA). AFB1 and OTA have been widely concerned due to their high toxicity and carcinogenicity. The existence of AFB1 and OTA will not only pose a potential hazard to the health of consumers, but also have a negative impact on the import and export trade of agricultural products in China. Therefore, this paper mainly studies the rapid detection methods of AFB1 and OTA in food to provide a basis for the establishment of AFB1 and OTA in food. Specific research results are as follows:1. An acetylcholinesterase-based amperometric biosensor was developed for rapid detection of aflatoxin B1 based on the mechanism of acetylcholinesterase inhibition by aflatoxin B1. The optimal pH of PBS buffer solution was 7.3, the optimal mass fraction of glutaraldehyde was 0.5%, the immobilized amount of AChE was 0.24 U, and the optimal inhibition time was 18 min. Under the optimal conditions, the standard curve is established. The linear range was 3.00~14.00 μg/m L, it shows a good linear relationship and the detection limit of aflatoxin B1 that was 0.86 μg/m L. And then the sample was detected. The method is simple and economical, and it is suitable for onsite detection.2. Based on the Gold nanoparticles covalently bound the functionalized porous carbon(cPC-AuNPs), a composite nano material was established for the detection of OTA impedance type electrochemical DNA sensor. Accroding to scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and electrochemical characterization, cPC-AuNPs’ good biocompatibility and huge specific surface area has been confirmed, so It can be used as an excellent carrier for the immobilization of aptamer. According to the structure of the electrochemical sensing interface, the solid loading of the aptamer can be improved, and the signal of the electrochemical detection can be amplified. 50 mmol/L Tris-HCl(pH 7.4, 0.2 mol/L NaCl, 1.0 mmol/L EDTA) buffer was used as DNA hybridization buffer solution, cPC-AuNPs-DNA1 optimal incubation time was 2 h, the optimum concentration of DNA2 was 10 μmol/L, and the optimal hybridization time for DNA2 with DNA1 was 2 h, prepared by high sensitivity DNA2/cPC-AuNPs-DNA1/GCE aptamer sensors.3. The DNA2/cPC-AuNPs-DNA1/GCE aptamer sensor for OTA achieved a high sensitivity detection. The electrochemical aptamer sensor mechanism of action of OTA has been studied out. The results showed that: the determination of the optimal incubation time OTA was 9 min, DNA2/cPC-AuNPs-DNA1/GCE aptamer sensor with good specificity and reproducibility. Under the optimal conditions, the standard curve is established. The linear range was 1×10-8~0.1 ng/m L, it shows a good linear relationship and the limit of detection is 1×10-8 ng/mL. The sample of Soybean was detected, and the average recovery rate was 101.67%. In this study, the development of the application of composite nanomaterials to achieve a double signal amplification, improved aptamer sensitivity of the sensor, which greatly reduces the detection limit.