Active Radicals Enriched by the Nanoconfinement Effect Synergistically Enhance Electrochemiluminescence with a Co-Reaction Accelerator for Zearalenone Detection

The inferior electron transfer efficiency and energy dissipation during mass transport processes constitute the fundamental limitations responsible for diminished electrochemiluminescence (ECL) efficiency. To address this critical issue, a synergistic approach combining nanoconfinement effects with co-reactant acceleration strategies was implemented, significantly enhancing ECL performance. Initially, copper sulfide nanoparticles (CuS NPs) were encapsulated within the covalent organic framework (COF) through the embedding method, followed by the in situ synthesis of gold nanoclusters (AuNCs) within the COF pores, ultimately yielding the high-performance ECL emitter AuNCs@CuS@COF. CuS NPs serve as an efficient co-reactant accelerator, catalyzing peroxydisulfate to generate abundant active free radicals, while the COF's nanoconfinement effect enhances the interaction efficiency between these radicals and the luminescent AuNCs, significantly amplifying ECL emission. Furthermore, a sensitive "off-on" ECL biosensor was constructed utilizing Cu²⁺-dependent DNAzyme. In the presence of zearalenone (ZEN), the DNAzyme walker, activated by Cu²⁺, cleaves the quencher-labeled substrate strands, restoring the ECL signal for accurate ZEN detection. Under optimized conditions, this ECL platform was demonstrated with a wide linear range (10^-4 to 10² ng/mL), an ultralow detection limit (0.052 pg/mL), excellent stability, remarkable specificity, and robust practicality, establishing a novel approach for mycotoxin detection in food safety monitoring.