Synergistic integration of bidirectional PER and DNAzyme cascades with ZIF-8 quenching for detection of aflatoxin B1

Aflatoxin B1 (AFB1), classified as a Group 1 human carcinogen by the International Agency for Research on Cancer (IARC), poses significant risks to food safety and public health owing to its potent hepatotoxicity and genotoxicity, as well as its remarkable thermal and chemical stability. Conventional detection methods face limitations such as complex instrumentation, high operational costs, and the risk of cross-reactivity. Herein, we developed a highly sensitive fluorescent biosensor leveraging the synergistic integration of bidirectional primer exchange reaction (BPER) amplification, DNAzyme-mediated cleavage, and ZIF-8-induced fluorescence quenching. The sensor employs an AFB1-triggered cascade reaction wherein target recognition induces reassembly of split DNAzyme fragments into a catalytically active enzyme. This enzyme cleaves a FAM-labeled reporter probe, generating a truncated product with diminished affinity for ZIF-8 nanoparticles. This results in a fluorescence "turn-on" signal quantitatively correlated with AFB1 concentration. The system achieves high sensitivity and specificity by combining programmable DNA length modulation with ZIF-8's efficient quenching properties, offering a robust platform for rapid, on-site AFB1 detection in food samples.