Construction Of Detecting Aflatoxin B₁ Based On Immunomagnetic Technology

Aflatoxin B₁（Aflatoxin B₁,AFB₁）is one of the secondary metabolites of Aspergillus fungi.It is highly harmful and has a wide range of pollution effects.Corn,peanuts and other cereal crops and oil crops are all vulnerable to pollution.It is also one of the most effective carcinogens found in nature at present,and was designated as a Class I carcinogen by the International Research Organization as early as 2002.Studies have speculated that due to global climate change,it will be beneficial to the growth and spread of Aspergillus flavus.At that time,the risk of aflatoxin contamination in corn in southern and central Europe is likely to continue to expand in the next 30 years.Besides,AFB₁ can transfer between organisms through the food chain,resulting in toxic accumulation,which poses a massive threat to the metabolic cycle.If pregnant or lactating women accidentally eat food contaminated by AFB₁,it may reduce human fertility.In view of the potential threat of AFB₁,in recent years,countries and international organizations have set more and more stringent testing requirements,and various scientific researchers are also working hard to develop and establish effective AFB₁ measurement methods.Immunomagnetic technology,which isa type of technology using immunomagnetic beads,was first used in medical cell sorting.Generally,it can be divided into positive screening enrichment and negative screening enrichment methods.With the rapid rise of nanotechnology,the magnetic nanoparticles at the core of immunomagnetic beads have better apparent physical properties.Immunomagnetic technology combines the strengths of nanomaterials and biometric technology and has unique advantages:（1）There are many surface active groups,good modifiable properties,and great potential for development and utilization.（2）Excellent biocompatibility,can be fully mixed with the sample to be tested,and the use efficiency is high.（3）With superparamagnetism,it is convenient to separate the solution,concentrate the solute,and provide the magnetic signal.Based on immunomagnetic technology,our study established a method for detecting AFB₁.Respectively realized:（1）A method of separating AFB₁ based on immunomagnetic beads.The EDC/Sulfo-NHS method was used to prepare immunomagnetic beads.The optimal conditions for optimizing immunomagnetic beads’preparation process were:p H=7.4,time 1.5 h,50μg antibody:1 mg magnetic beads.For AFB₁ enrichment in the buffer,the best conditions are:20%methanol in PBS as the enrichment buffer,the enrichment time is 10 minutes,and the amount of immunomagnetic beads added is 0.8 mg:5 ng AFB₁.（2）The establishment of a flow cytometry fluorescence immunoassay method for AFB₁based on immunomagnetic beads.The LOD detected by this method for AFB₁ in the buffer is 0.2034μg/L,LOQ is 0.5659μg/L;the linear range is 0-3μg/L,and the linear regression equation is:y=0.06211*x+0.008890.（3）The establishment of a smart phone-assisted paper-based microfluidic chip（μPADs）method for detecting AFB₁ based on immunomagnetic beads.The LOD of this method for AFB₁ in the buffer is 9.45 ng/m L,and the LOQ is 12.00 ng/m L;the linear range is 8-25ng/m L,and the linear regression equation is:y=-1.106*x+29.28.