A dual-mode γ-CD/Fe,N-CD nanozyme enabled by host-guest interactions for the dual-mode fluorometric and colorimetric monitoring of zearalenone in wheat flour.

Abstract

Zearalenone (ZEN), a potent endocrine-disrupting mycotoxin produced by Fusarium fungi, frequently contaminates cereal-based foods worldwide, necessitating reliable analytical methods for food safety and regulatory compliance. Herein, we report an innovative dual-readout sensing strategy for both fluorometric and colorimetric quantification of ZEN, based on a unified catalytic nanoplatform of iron and nitrogen co-doped carbon dots decorated with γ-cyclodextrin (γ-CD/Fe, N-CDs). The enlarged macrocyclic cavity of γ-CD selectively accommodates the bulky 14-membered resorcylic acid lactone ring of ZEN via host-guest binding, simultaneously triggering two distinct signaling pathways: static quenching of the intrinsic carbon dot fluorescence through ground-state complex formation, and inhibition of TMB oxidation as the captured ZEN scavenges hydroxyl radicals generated by the proximal iron catalytic centers, reducing colorimetric signal intensity in a dose-dependent manner. The fluorescence channel exhibited linearity over 0.5-80.0 ng mL^-1 with an LOD of 0.21 ng mL^-1, while the colorimetric channel was linear over 5.0-55.0 ng mL^-1 with an LOD of 1.6 ng mL^-1. Applied to commercial wheat flour samples, the method yielded recoveries of 95.8-102.4% with RSDs below 4%, showing no significant deviation from conventional reference techniques. This bifunctional nanodevice offers a robust, mutually corroborating dual-channel platform for high-throughput ZEN surveillance in grain commodities.