Development Of Rapid Detection Instrument For Aflatoxin B₁ Based On Immunosensor

Aflatoxin B₁(AFB₁)seriously threatens the safety of agricultural products.Long-term intake of AFB₁ can easily lead to cancer and other diseases.In order to protect human health,it is urgent to develop rapid and accurate detection methods and instruments to strictly control the content of Aflatoxin B1 in agricultural products.In this study,two kinds of AFB₁ immunosensors based on electrochemical and electrochemiluminescence?ECL?were constructed.The electrochemical signal and ECL signal characteristics of the immunosensor and the relationship between the two signals were studied respectively.A fast detector for determining the concentration of AFB₁ by combining the two signals was developed.1.Preparation of immunosensor based on multi-walled carbon nanotubes?MWCNTs?@nano-tin antimony oxide?ATO?:Using the good adhesion of chitosan?CS?,MWCNTs and ATO were evenly dispersed to form uniform MWCNTs@ATO-CS nanocomposites.The nanocomposites,anti-AFB₁ antibody?Ab?and bovine serum albumin?BSA?were modified on screen-printed electrodes?SPCE?by layer-by-layer self-assembly.BSA/Ab/MWCNTs@ATO-CS/SPCEs immunosensor was established to detect AFB₁.The specific immune reaction between the tested AFB₁ and Ab in the immunosensor hinders the electron transfer on the surface of SPCE.The higher the concentration of AFB₁,the greater the hindrance.The concentration of AFB₁ is determined by the current difference before and after the reaction.The results showed that the AFB₁ immunosensor had a good linear relationship in the concentration range of 10^-3-10³ ng/mL,and the detection limit was3 pg/mL.2.Preparation of ECL immunosensor based on nano-titanium dioxide@tin antimony oxide?ATO?:Luminol was modified on the surface of platinum electrodes to prepare luminescent electrodes with ECL characteristics by using the chemiluminescence properties of luminol-H₂O₂ in alkaline solution.Titanium dioxide and ATO were doped with chitosan to form titanium dioxide@ATO-CS nanocomposites,which were modified on the luminescent electrode to enhance the ECL strength of the electrode and provide more binding sites for the luminol-H₂O₂ reaction.An ECL immunosensor was established for the detection of AFB₁ by layer-by-layer self-decoration of Ab and BSA.The specific combination of AFB₁ and Ab weakens the ECL intensity of Luminol.The concentration of AFB1 can be determined according to the strength of ECL detected.The results showed that the linear concentration range of the ECL immunosensor was in 10^-3-10² ng/mL and the detection limit was 0.03 ng/L..3.Development of a rapid detection instrument for aflatoxin B₁:Based on cyclic voltammetry?CV?method,a new type of AFB₁ rapid detection instrument was designed.Response current and ECL signals were obtained by CV scanning.The concentration of AFB1 was calculated according to current signal and light intensity signal respectively.The two kinds of AFB₁ concentration were compared.The results of higher concentration were taken as the final determination of the concentration of AFB₁.This method solved the problem of increasing measurement error caused by multiple measurements of traditional instruments.The detector was finally developed successfully by analyzing the functional requirements of the detector,planning the overall solution,selecting and designing key components and circuits,and programming with the program.The detector was used to detect the recovery of AFB₁ in peanut oil,and the recovery was in range of 86.8%-109.3%.The rapid detector solves the problem that the immune sensor method needs to measure two times to detect AFB₁,and improves the accuracy and stability of the instrument.