Selection, identification, and application of Aflatoxin B1 aptamer

Aflatoxins represent an important class of mycotoxins that are known to be mutagenic, carcinogenic, and teratogenic. Here, we report the use of the systematic evolution of ligands by exponential enrichment technology to screen for a DNA aptamer that recognizes Aflatoxin B1 (AFB1) with high affinity and specificity. AFB1 was first attached to magnetic nanoparticles and then incubated with an ssDNA library. After ten rounds of screening and amplification, 30 aptamer sequences were obtained following enrichment. Combined with a homological and structural analysis and affinity and specificity experiments, aptamer sequence 1, possessing the best affinity and specificity toward AFB1, was finally obtained. The dissociation constants value for aptamer sequence 1 was 11.39 nM. And, the specificity experiment results showed the binding between AFB1 aptamer with five other toxins was very week (did not exceed 15 % compared with AFB1). To demonstrate the potential use of this aptamer for quantitative analysis, a fluorescent bioassay with aptamer 1 was developed. The assay showed a wide linear range, with the AFB1 concentration ranging from 50 to 1,500 ng/L and a detection limit of 35 ng/L. Additionally, the spiked recovery experiment of AFB1 in peanut oil sample exhibited a recovery ratio between 94.2 and 101.2 % which showed good accuracy of the proposed aptamer-based bioassay. This fluorescent method represents a powerful tool for use in the detection of AFB1 without complex sample treatments.