A label-free immunoassay protocol for aflatoxin B1 based on UV-induced fluorescence enhancement.

As one of the most toxic chemical carcinogens, aflatoxin B1 (AFB1) has attracted extensive attention due to its severe impairment to human health. There exists urgent demand to develop facile and sensitive method for rapid screening of AFB1. Here magnetic beads modified with mouse monoclonal antibody (McAb) were adopted for capture and enrichment of the mycotoxin in sample matrix. Then UV radiation at 365 nm was utilized to induce the enhancement of fluorescent (FL) emission of the captured AFB1 with an addition reaction. The FL signal of the derivative at 435 nm was collected to quantify AFB1. The immunoassay method for AFB1 showed a wide detection range of 1.0-1000 ng mL, with a low detection limit of 0.21 ng mL (3σ). It was applied to detect AFB1 in herbal medicines including Astragalus membranaceus and Salvia Miltiorrhiza, with acceptable recovery values of 95.4-107.7%. It shows many merits including facile manipulation, low cost, high sensitivity and ideal selectivity. Due to its simple detection mechanism, the UV-induced FL derivatization-based label-free immunoassay can be furtherly extended to detection of other mycotoxins with similar chemical structures.