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Time-Resolved Fluorescence Immunochromatographic Assay Developed Using Two Idiotypic Nanobodies for Rapid, Quantitative, and Simultaneous Detection of Aflatoxin and Zearalenone in Maize and Its Products

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posted on 2017-09-13, 00:00 authored by Xiaoqian Tang, Peiwu Li, Qi Zhang, Zhaowei Zhang, Wen Zhang, Jun Jiang
Aflatoxins and zearalenone (ZEN) are highly common mycotoxins in maize and maize-based products. This study aimed to report a time-resolved fluorescence immunochromatographic assay (TRFICA) developed using two idiotypic nanobodies for rapid, quantitative, and simultaneous detection of aflatoxin B1 (AFB1) and ZEN in maize and its products. A novel Eu/Tb­(III) nanosphere with enhanced fluorescence was prepared as a label and conjugated to anti-idiotypic nanobody (AIdnb) and monoclonal antibody (mAb). On the basis of nanosphere–antibody conjugation, two patterns of competitive time-resolved strip methods (AIdnb–TRFICA and mAb–TRFICA) were established and compared. The half inhibition concentration of AIdnb–TRFICA was 0.46 and 0.86 ng·mL–1 for AFB1 and ZEN, which was 18.3- and 20.3-fold more sensitive than that of mAb–TRFICA for AFB1 and ZEN, respectively. Under optimal conditions, AIdnb–TRFICA for dual mycotoxin was established and provided a quantitative relationship ranging from 0.13 to 4.54 ng·mL–1 for AFB1 and 0.20 to 2.77 ng·mL–1 for ZEN, with a detection limit of 0.05 and 0.07 ng·mL–1 in the buffer solution, respectively. AIdnb–TRFICA showed good recoveries (72.6%–106.6%) in samples and was applied to detect dual mycotoxin in maize samples with satisfying results. To the best of our knowledge, it is the first report about a time-resolved strip method based on AIdnbs for dual mycotoxin.