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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Food and Feed Safety Research » Research » Publications at this Location » Publication #316110
Title: An ultra-sensitive monoclonal antibody-based fluorescent microsphere immunochromatographic test strip assay for detecting aflatoxin M1 in milk

Author
item ZHANG, XIYA - China Agricultural University
item WEN, KAI - China Agricultural University
item WANG, ZHANHUI - China Agricultural University
item JIANG, HAIYANG - China Agricultural University
item Beier, Ross
item SHEN, JIANZHONG - China Agricultural University

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2015
Publication Date: 8/30/2015
Publication URL: http://handle.nal.usda.gov/10113/62655
Citation: Zhang, X., Wen, K., Wang, Z., Jiang, H., Beier, R.C., Shen, J. 2015. An ultra-sensitive monoclonal antibody-based fluorescent microsphere immunochromatographic test strip assay for detecting aflatoxin M1 in milk. Food Control. 60:588-595.

Interpretive Summary: An immunochromatography test strip (ICTS) is a popular screening tool for conducting onsite testing because of its sensitivity, rapidity, and user-friendliness. The ICTS is an easy-to-use test and is similar to commonly used over-the-counter pregnancy tests. Here we developed an anti-aflatoxin M1 monoclonal antibody with high specificity to be used as the reagent in the ICTS. Antibodies are substances that are produced by the immune system in response to foreign substances which enter the body. Once the antibodies to a foreign substance are isolated, they can be used in a method to detect the presence of that foreign substance. We also used fluorescent microspheres (FMs) to improve the sensitivity of the ICTS for aflatoxin M1. After optimization, a highly specific and sensitive competitive immunochromatography assay was developed for aflatoxin M1 with an IC50 value of 36.3 ng/L and a detection limit (LOD) of 4.4 ng/L in milk using a fluorescence reader. The recoveries of aflatoxin M1 ranged from 76.6 to 110.8% with a coefficient of variation (CV) of 4 to 14.7%. The whole procedure could be completed within a 30 minute time span. The results demonstrated that the FMs-ICTS is easy to conduct, rapid, highly sensitive, and specific for the detection of aflatoxin M1 residues in milk.

Technical Abstract: A rapid lateral flow fluorescent microspheres immunochromatography test strip (FMs-ICTS) has been developed for the detection of aflatoxin M1 (AFM1) residues in milk. For this purpose, an ultra-sensitive anti-AFM1 monoclonal antibody (MAb) 1D3 was prepared and identified. The IC50 value of the MAb 1D3 for AFM1 was 23 ng L^–1, and the cross-reactivity (CR) of the MAb with aflatoxin M2, aflatoxin B1, aflatoxin B2, aflatoxin G1, and aflatoxin G2 were 17%, 9%, 0.15%, 42%, and 0.3%, respectively. The MAb was covalently conjugated with carboxylate-modified fluorescent microspheres (FMs), and the FMs were used as the label in a competitive immunochromatography assay. Under optimal conditions, the IC50 value of the assay was 36.3 ng L^–1 with the limit of detection (LOD) of 4.4 ng L^–1 in milk samples using a fluorescence reader, and the recoveries of AFM1 in spiked milk samples ranged from 76.6 to 110.8% with coefficient of variation (CV) of 4–14.7%. The whole procedure could be completed within 30 minutes. The results demonstrated that the FMs-ICTS is easy to conduct, rapid, highly sensitive, and specific for the detection of AFM1 residues in milk.