An amplifiable ratiometric fluorescent aptasensor for aflatoxin B1 detection based on dendrimer-like DNA nanostructures coupled with catalytic hairpin self-assembly

Herein, an amplifiable ratiometric fluorescent aptasensor was constructed based on dendrimer-like DNA nanostructures coupled with catalytic hairpin self-assembly for the specific detection of aflatoxin B1 (AFB1) in food. Compared with the single-signal mode, the ratio-signal mode based on FCy3/FCy5 has a wider linear range and a higher R2 for the detection of AFB1. Moreover, for the spiking experiment of peanut, soybean and wine samples, taking the average of the recovery obtained by three standard curves of FCy3, FCy5, FCy3/FCy5 as the reference value, the ratio-signal-based aptasensor showed higher accuracy than the single-signal-based aptasensor. In addition, the presence of a dendrimer-like scaffold can not only improve the stability of the sensor but also enhance FRET efficiency. In the whole detection process, the specific signal difference with dendrimer-like DNA nanostructures was 5.7 times of that without dendrimer-like DNA nanostructures. Besides, catalytic hairpin self-assembly, an enzyme-free amplification strategy, was introduced to achieve signal amplification by the complementary chain of the aptamer (c-DNA) cycle. Furthermore, the sensor can detect various mycotoxins in food by different aptamer recognition.