A novel fluorescent aptasensor based on H-shaped DNA nanostructure and hollow carbon-doped nitrogen nanospheres for sensitive detection of AFB1

Abstract

The existence of aflatoxin B1 (AFB1) in food has a high carcinogenic effect on humans and animals. In this study, a fluorescent aptasensor for AFB1 detection was studied by designing a unique H-shaped DNA nanostructure and using novel hollow carbon-doped nitrogen nanospheres (HCNS) as the quenching material. The two DNA strands were hybridized to form the skeleton of the H-shaped DNA nanostructure, and the signal probe (S1-FAM) was paired with complementary bases to form the complete H-shaped DNA nanostructure. When AFB1 was absent, the S1-FAM was replaced by AFB1-Apt and was adsorbed by HCNS to generate a fluorescence resonance energy transfer effect (FRET), causing the signal to turn off. In the presence of AFB1, AFB1 specifically bound to AFB1-Apt to form a complex, which led to the stable formation of the S1-FAM into the H-shaped DNA nanostructure, resulting in the signal turn-on. Under the optimal conditions, an excellent linear relationship (R2 = 0.992) was observed between LgCAFB1 and fluorescent intensity ratio in the range of 0.05–500 ng/mL, and the detection limit was 0.023 ng/mL. The designed aptasensor platform was applied to analyze the spiked AFB1 in peanut, corn flour, wheat flour, wine, and black tea with recoveries ranging from 93.6% to 107.2%.