Development and analysis of a novel AF11–2 aptamer capable of enhancing the fluorescence of aflatoxin B1

Aflatoxin B1 (AFB1) is one of the most common mycotoxins that threatens human health. As single-stranded oligonucleotides with high affinity and specificity, aptamers have incomparable effect on the targeted detection of AFB1. Herein, after 11 rounds of selection and analysis using a modified affinity chromatography-based SELEX strategy, the truncated 37 nt aptamer AF11–2 was successfully obtained. The aptamer shows good detection performance for AFB1, and can sensitively detect AFB1 in the range of 100–1000 nmol/L, with a detection limit of 42 nmol/L. In the detection of pretreated edible peanut oil samples, AF11–2 aptamer also showed a high recovery rate and good stability for AFB1, and achieved satisfactory results. In addition, AF11–2 aptamer can significantly enhance the fluorescence ability of AFB1, which is not available in traditional Afla17–2–3 aptamer. After molecular docking analysis, it was found that AF11–2 and Afla17–2–3 had different nucleotide binding sites for AFB1. Afla17–2–3 binds to the carbonyl O of AFB1, while AF11–2 binds to the pyrrolic O of AFB1, which may be the main reason that AF11–2 can enhance the fluorescence of AFB1.