| Corn is one of the most important economic crops in the world,especially in Asian cou ntries.The main producing countries are China,India,Indonesia,Bangladesh,Vietnam and Thailand.Just like other cereal crops,corn is also susceptible to fungal infections during sto rage.Fungal infections in corn can cause mycotoxin contamination,mainly aflatoxins,ochr atoxins,fumonisins and deoxynivalenol.Among them,the most toxic is aflatoxin B1（AFB1）,which belongs to a kind of aflatoxins,mainly produced by Aspergillus flavus and Asperg illus parasiticus,and is currently the most toxic mycotoxin known.The International Agenc y for Research on Cancer believes that AFB1 is carcinogenic to humans and mainly affects t he liver.AFB1 is also considered to be mutagenic,teratogenic and hepatotoxic.This mycoto xin is often found in moldy agricultural products,and has a higher chance of appearing in hi gh-heat and humid environments,which is conducive to the growth of fungi.Aflatoxins are widely distributed in food ingredients such as corn,peanuts,milk,and grains.And it is not e asy to inactivate it during the cooking process.Therefore,early detection of AFB1 in stored corn and grains is important to reduce the risk of AFB1 contamination in the food chain.Ma ny technologies have been developed to detect AFB1 in a variety of samples,including thin layer chromatography（TCL）,high performance liquid chromatography（HPLC）,enzyme-li nked immunosorbent assay（ELISA）,liquid chromatography tandem mass spectrometry（L C-MS）/MS)and Electrochemical Biosensor,Immunochromatography Assay.The current analytical methods for quantitative AFB1 mainly include chromatographic techniques and i mmunoassays.Chromatography methods such as high performance liquid chromatography（HPLC）and liquid chromatography-mass spectrometry（LC-MS）are commonly used to acc urately and sensitively detect AFB1,however these conventional techniques rely on expensi ve instruments and require complex pretreatment processes,And require skilled operators.At present,these methods are only suitable for operation in the laboratory and are not suitab le for rapid on-site testing.However,the current mainstream immunochromatography techn ology uses colloidal gold as a marker.Although it is suitable for on-site rapid detection,its s ensitivity is low and quantitative detection cannot be achieved.In this study,quantum dot nanobeads were used as a labeling substance to replace the mainstream colloidal gold on the market,combined with a portable fluorescence reader,and an independent quality control line（C line）system was used to establish a quantum dot nanobeads immunochromatographic test strip test,which could detect aflatoxin B1.After a series of optimization of conditions,the p H and the amount of antibody when the quantum dot microspheres are coupled to the antibody;the streak concentration and the time of the reaction chromatography are determined to make the test strips have better results.The detection range of the established aflatoxin B1 quantum dot nanobeads test strip detection method is analyzed,and the linear range of quantitative detection is 0.025ng/mL～1.0 ng/mL,and the linear range formula is y=-0.44203logx+1.45572.The detection limit is 0.01 ng/mL.Then it evaluated the accuracy,specificity,repeatability,save potential and other important parameters of the established method:the concentration of the sample detected by the test strip is highly consistent with the result detected by the HPLC method,and the accuracy is high;It has no cross-reactivity with biotoxins such as ochratoxin A,zearalenone,fumonisin B1,deoxynivalenol,and has good specificity;Experiments with different batches of test strips showed that the coefficient of variation was less than 15%,which proved the stability of the test strips was very good;Under the storage conditions of 25℃ and 37℃,the results detected for four consecutive weeks are basically consistent with the actual concentration,indicates that it has the potential for long-term preservation.Using actual corn flour samples to carry out the spiked recovery test,the spiked recovery rate was 83.1%～109.6%,and the coefficient of variation was 7.3%～10.4%,which indicated that the established quantum dot microsphere test strip was used to detect the actual corn flour.The sample still maintains good accuracy.In the detection of actual corn meal negative and positive samples,the specificity reached 100%and the sensitivity reached 97.5%.It is proved that the established test strip for quantitative detection of aflatoxin can be applied to the detection of actual corn flour samples. |
