Precision-SELEX aptamer screening for the colorimetric and fluorescent dual-readout aptasensing of AFB1 in food
As nucleic acid-based affinity elements, aptamers have attracted significant attention for a wide range of analytical applications. Although several aflatoxin B 1 (AFB 1 ) aptamers have been identified, they are unsuitable for overcoming the unavoidable cross-reactions from interferents in complex food matrices due to their poor binding affinities and specificities. Herein, a novel precision-systematic evolution of ligands by exponential enrichment (P-SELEX) strategy through introducing the counter (matrix without target AFB 1 ) and positive (with AFB 1 ) screening steps was implemented to accurately identify AFB 1 aptamers. A DNA aptamer A-42-2 at a 24-nt length was selected finally, which possessed nanomolar-level affinity of 5.55 nM, high specificity to other interferents, and strong anti-cross-reactivity ability for matrix components. Then, an A-42-2 aptamer-based ultra-sensitive colorimetric and fluorescent dual-readout aptasensor was fabricated for AFB 1 detection in three kinds of complex food samples rich in starch without cross-reactions. The aptasensor displayed outstanding detection capacity with a wide liner range of 0.25–30 nM (1.95–234.4 μg/kg), while the detection limit for colorimetric measurement as low as 0.22 nM (1.72 μg/kg) and 0.048 nM (0.20 μg/kg) for fluorescent determination. P-SELEX is ideal for screening and applying aptamers in complex food matrices, creating more opportunities for the efficient and cost-effective development of high-quality aptamers and aptasensors for other targets.
危险品化学品经营许可证（带存储）