Abstract: Aflatoxin B1 (AFB1) is the most toxic member of the aflatoxin family, which, even at trace levels, poses a serious threat to food safety and human health. In this study, a composite material designated Ag NPs/MXenes was successfully prepared by anchoring silver nanoparticles (Ag NPs) onto MXene nanosheets. This material served as an efficient co-reaction accelerator in the Luminol-H2O2 electrochemiluminescence (ECL) system, significantly enhancing both the stability and intensity of the ECL signal. Using Ag NPs/MXenes as the sensing substrate and integrating it with the CRISPR/Cas12a system, an ECL resonance energy transfer (ECL-RET)-based “off-on” switch-type biosensor was constructed for the detection of AFB1. In the presence of the target AFB1, the aptamer specifically binds to AFB1, resulting in the release of an activator strand that triggers the trans‑cleavage activity of CRISPR/Cas12a. The aptamer‑regulated activation of Cas12a enabled highly sensitive quantification of AFB1. The sensor exhibited a good linear response over the concentration range of 1 pg/mL to 100 ng/mL, with a detection limit as low as 0.4 pg/mL. Its application in real samples demonstrated satisfactory applicability. This sensor offers an efficient point-of-care testing (POCT) strategy for the early monitoring of AFB1 contamination.

Key words: silver nanoparticles/MXenes; aflatoxin B1; electrochemiluminescence sensor; rapid detection; CRISPR/Cas12a