A label-free aptasensor for dual-mode detection of aflatoxin B1 based on inner filter effect using silver nanoparticles and arginine-modified gold nanoclusters

To avoid potential health risks associated with the ingestion of aflatoxin B1 (AFB1) contaminated foods, development of a simple and sensitive method for AFB1 detection is urgently needed. Herein, a label-free aptasensor for colorimetric/fluorometric dual-mode detection of AFB1 was developed. In the absence of AFB1, the aptamer-protected silver nanoparticles (AgNPs) were prevented from salt-induced aggregation and the solution remained yellow. In the presence of AFB1, the aptamer preferentially bound to AFB1, which was subsequently desorbed from the surface of AgNPs and leading AgNPs to aggregate in salt solution and color changed to gray. Then, the arginine-modified light-emitting enhanced gold nanoclusters (AuNCs) were introduced into reaction system, which successfully converted the color signal into more sensitive fluorescence signal via perfect spectral overlap-mediated inner filter effect (IFE). The fluorescence quenching efficiency decreased with increasing concentrations of AFB1 and the fluorescence of aptasensor gradually recovered. The fluorometric aptasensor exhibited excellent response to AFB1 concentration in the range of 5-400 ng/mL and the limit of detection (LOD) was 1.91 ng/mL, which achieved a 6.4-fold improvement compared to colorimetric aptasensor. The practicability and reliability were validated in corn and wheat samples. The aptasensor develop here integrate advantages of label-free, dual-signal, self-calibration, easy operation, and cost-effectiveness, and then provide a powerful tool for rapid and sensitive detection of mycotoxins in foodstuffs.