Inner-filter effect based fluorescence-quenching immunochromotographic assay for sensitive detection of aflatoxin B1 in soybean sauce

A fluorescence-quenching immunochromotographic assay (ICA) was developed for sensitive detection of aflatoxin B1 (AFB1) in soybean sauce based on the inner filter effect (IFE) between flower-like gold nanoparticles (AuNFs) and quantum dots (QDs). QDs were sprayed on the test and control line zones as background fluorescence signals, whereas AuNFs were designed as the fluorescence absorber of QDs because the surface plasma resonance peak of AuNFs totally matched with the maximum emission peak of QDs. Under the optimal conditions, the fluorescence-quenching ICA strip showed a good linear detection for AFB1 in standard AFB1 solution from 0.008 μg/L to 1 μg/L with a low detection limit of 0.004 μg/L. The average recoveries for different concentrations of AFB1-spiked soybean sauce samples ranged from 84.69% to 120.44% with a coefficient of variation ranging from 2.73% to 10.41%. In addition, the reliability of the proposed method was further confirmed by ultra-performance liquid chromatography with fluorescence detection method. In brief, this novel IFE-based strip offers a simple, rapid, sensitive, and accurate strategy for quantitative detection of AFB1 in soybean sauce.