Research On Detection For Mycotoxins Of Stored Grain Based On Microfluidic

Grain is an important strategic reserve material,which is highly susceptible to contamination by mycotoxins during storage.The current traditional chemiluminescent enzyme immunoassay method for detecting mycotoxins has problems such as time-consuming,high measurement cost,and difficulty in improving measurement accuracy,which have become the main constraints for the promotion and application of immunoassay in the grain industry.To address the shortcomings of traditional methods,this paper combines magnetic particle chemiluminescence technology and microfluidics to design a microsystem for mycotoxin detection in stored grains,which achieves time-saving,low-cost and high-precision detection of mycotoxins.The main work of the paper is as follows:(1)Study of the coupling characteristics between chemiluminescence and optical fiber in the microsystem case.By comparing with the traditional detection method,it is shown that the use of optical fiber detection can reduce the detection error and improve the detection accuracy;the simulation modeling of the coupling between chemiluminescence and optical fiber in the microsystem case shows that the change rate of the coupling efficiency between optical fiber and chemiluminescence in the vertical range of 0.5～5 mm above the microreaction cavity is less than 1%,which indicates that the fixed optical fiber in a certain area above the microreaction cavity,the position of the optical fiber The offset has a small effect on the final measurement results.(2)Construction of a microfluidic-based mycotoxin detection system for grain storage.The detection system consists of a master control module,microfluidic chip,photon counting module,sample addition module,dark box,constant temperature and humidity chamber,etc.The design and fabrication of the microfluidic chip was accomplished by simulating and testing the chemiluminescence detection of different sizes of microfluidic chip reaction cavities,which were determined to be 3mm in diameter at the bottom of the cylindrical reaction cavity and 1mm in height.The system uses a micro syringe pump with a syringe to precisely spike the reaction cavity,and a fiber optic type photon counting probe combined with a multimode fiber to achieve chemiluminescence signal acquisition in the reaction cavity.The dark box and constant temperature and humidity chamber are used to provide a stable detection environment.The QT design is used to write the upper computer interface to realize the real-time display and storage function of the detection data.(3)The calibration curves of fungal toxin content and chemiluminescence intensity in the microsystem case were established and experimentally validated.Determine the optimal test parameters such as luminol concentration,hydrogen peroxide concentration,chemiluminescence reaction temperature and incubation temperature based on chemiluminescence intensity through experimental testing of microsystem chemiluminescence.Immobilization of magnetic particles with AFB1 antibodies by covalent coupling method to achieve antibody-coating of magnetic particles.The calibration curve of AFB1 content and chemiluminescence intensity in the microsystem case was established by the detection test of AFB1 standard samples,and the correlation coefficient was 0.9977,the linear range was 0-20 μg/L,and the IC50 was 3.44 μg/L.On this basis,the accuracy and precision of the method were determined experimentally,and the recoveries of the samples spiked were92.62～96.03 %,the relative deviations of the assays were less than 8%,and the CVs of the coefficients of variation were less than 3%.The results showed that the method has high linearity,sensitivity,accuracy and precision compared with the traditional detection method.