Determination of aflatoxin B1 in rice flour based on an enzyme-catalyzed Prussian blue probe

Aflatoxin B1 (AFB1) is a toxin that is widely present in food and feed and poses a serious threat to the health of humans and livestock. In this work, we proposed the quantitative detection method of AFB1 contamination using a simple, sensitive, and specific colorimetric immunoassay based on gold nanoparticles labeled with glucose oxidase (GOx)/rabbit anti-mouse immunoglobulin G. In our strategy, Prussian blue was produced by a GOx catalyst-assisted Fe3+ and Fe(CN)63− system, which was designed and employed as a probe. Without GOx, the Fe3+ and Fe(CN)63− system containing glucose did not produce Prussian blue, while under the catalyzation of GOx, the H2O2 generated from glucose oxidation reduced Fe3+ to Fe2+, resulting in a visible color change from yellow to blue. With an increase in AFB1 concentration, the absorbance at 706 nm gradually decreased linearly from 0.5 ng/mL to 5 ng/mL, with a detection limit of 0.35 ng/mL. Thus, acceptable recovery(g/100 g) (87.6–106.0) were achieved in the spiked rice flour samples. As a result, this simple, sensitive, and specific colorimetric method may be used for AFB1 evaluation in the food industry, and our work paves the way for the evaluation of other analytes using the respective antibodies.