Entropy-stabilized quinary sulfide nanozyme for complementary dual-mode detection of sulfonamide antibiotics via electrochemiluminescence and colorimetric sensing.

Current sulfonamide detection methods face a persistent trade-off between sensitivity and reliability in complex food matrices, particularly the vulnerability to false positives in single-mode assays. We report a dual-mode sensing platform based on the quinary high-entropy sulfide (FeCoCuCrZr)S2 (F3CZ-48), repurposing this entropy-stabilized nanozyme to independent yet complementary electrochemiluminescence (ECL) and colorimetric transduction for sulfadiazine (SD) detection. The homogeneous elemental distribution and mixed-valence states (Fe2+/Fe3+, Co2+/Co3+) enable two synergistic catalytic pathways: (i) oxygen reduction reaction (ORR) catalysis that generates hydroxyl radicals that amplify ECL intensity by 3.8-fold in luminol-based systems, and (ii) peroxidase-like activity with characterized kinetics. The ECL sensor achieves an ultralow detection limit of 19.6 pM for SD (linear range: 100 pM-100 μM, R2 = 0.998) with exceptional selectivity. Parallel colorimetric detection via TMB oxidation yields comparable quantification accuracy (94.8-116.0% recovery in milk/egg matrices, RSD 1.97-4.32%). Critically, the cross-modal consistency between ECL and colorimetric results provides mutual validation, effectively reducing the risk of spurious signals commonly encountered in single-mode assays. Operational stability (4.5% RSD over 10 cycles) and resistance to surface fouling in protein-rich matrices establish F3CZ-48 as a versatile platform that unifies electrochemical and optical sensing modalities for potential on-site food safety monitoring.