Dual-readout colorimetric immunoassay based on halogenated indophenol for rapid detection of aflatoxin B1

Aflatoxin B1 (AFB1) is one of the most toxic mycotoxins. In view of the great harm of AFB1, it has attracted much attention to explore a super-sensitive and low-cost rapid detection method for aflatoxin B1. Herein, a dual-readout colorimetric immunoassay was established for the detection of AFB1. Under the catalysis of alkaline phosphatase (ALP), phenyl phosphate (PP) can produce phenol by dephosphorylation. Then phenol can react with 2,6-dibromoquinone-4-chloroimide (DBQC) under alkaline conditions to produce blue halogenated indophenol (HIP). Through this reaction, the color of the solution became blue, which can be observed by the naked eye. In addition, this color signal can be converted into digital signal via smartphone, enabling quantitative detection of AFB1. Under the optimal condition, the detection limit of this colorimetric immunoassay was 0.70 ng/mL by naked eye and 0.013 ng/mL by smartphone. The application results showed that the proposed daul-readout colorimetric immunoassay was feasible and real-time for AFB1 detection in actual samples.