A ratiometric electrochemical zearalenone aptasensor based on Fc-Au-MoS2 nanosheet and triple-helix molecular switch-triggered cleavage effect of DNAzyme

Zearalenone (ZEN) is a mycotoxin that exerts multiple toxic effects on humans through the contamination of grains such as corn, posing a significant threat to food safety and human health. This work proposed a dual-signal ratiometric electrochemical aptasensor utilizing ferrocene-carboxylic acid‑gold nanoparticle‑molybdenum disulfide nanosheets (Fc-Au-MoS 2 ), hybridization chain reaction (HCR), and the cleavage effect of DNAzyme triggered by triple-helix molecular switch (THMS) to detect ZEN. The specific interaction with ZEN triggers the release of the DNAzyme from THMS, which then removes the immobilized primer chain on the electrode surface with the assistance of Pb 2+ , thereby preventing HCR occurrence. This inhibitory mechanism reduces methylene blue (MB) insertion while exposing the active sites of Fc-Au-MoS 2 , generating an opposite signal response to achieve high-precision ratio detection. The aptasensor demonstrated a low detection limit of 29.4 pM, with satisfactory recoveries in corn flour (97.3 %–106.4 %), confirming its potential for monitoring mycotoxin residues in food safety.