Ratiometric fluorescence/colorimetric dual-mode detection of tertiary butylhydroquinone in edible oils based on copper‑cerium oxide nanozyme and nitrogen-doped carbon dots

To ensure a sensitive and accurate assessment of potential health hazards posed by tertiary butylhydroquinone (TBHQ) in food products, we developed a novel ratiometric fluorescence-colorimetric dual-mode sensing system for TBHQ monitoring, which integrated copper‑cerium oxide nanocubes (Cu-CeO 2 NCs) with nitrogen-doped carbon dots (N-CDs). The Cu-CeO 2 NCs with excellent peroxidase-like activity could catalyze the H 2 O 2 -mediated oxidation of o -phenylenediamine (OPD) to fluorescent 2,3-diaminophenothiazine (DAP). The DAP exhibited ultraviolet absorption at 415 nm with fluorescence emission at 565 nm, that could quench the fluorescence of N-CDs at 469 nm via inner filter effect. TBHQ with strong antioxidant capacity inhibited the oxidation of OPD, thus restoring the fluorescence of N-CDs. Therefore, a dual-mode sensing platform was established for TBHQ analysis with the limits of detection of 0.64 and 0.81 μg/mL, respectively. This platform demonstrated good practicability through its successful implementation in detecting TBHQ in edible oils.