ZIF-8-Confined and APTES-Passivated CsPbBr₃ Quantum Dots for Fluorescence Detection of Enrofloxacin Residues in Foods

Enrofloxacin residues in foods pose potential risks to food safety and public health, creating demand for rapid, sensitive, and matrix-compatible screening methods. All-inorganic CsPbBr₃ quantum dots (QDs) are promising fluorescent probes because of their strong photoluminescence, but their poor stability in polar media greatly restricts their practical use in food analysis. Herein, ZIF-8-confined and APTES-passivated CsPbBr₃ QDs were developed as an ethanol-compatible fluorescent sensor for enrofloxacin detection in foods. Unlike reported CsPbBr₃@ZIF-8 systems mainly used for metal-ion sensing in aqueous media, this work integrates ZIF-8-confined in-situ growth with APTES-assisted silane passivation to improve the stability and applicability of CsPbBr₃ QDs in ethanol-based food extracts. ZIF-8 provided a confined microenvironment, while the APTES-derived silane layer further enhanced fluorescence stability. The sensor exhibited a distinct turn-off fluorescence response toward enrofloxacin, with a linear range of 0.1-25.0 mg·L^-1 and a limit of detection of 0.058 mg·L^-1, mainly attributed to electron transfer with CsPbBr₃@ZIF-8. The method was successfully applied to honey, milk, fish, and shrimp samples, achieving recoveries of 85.2-106.8%. Results obtained for aquatic products showed no significant difference from HPLC analysis (p > 0.05), demonstrating the potential of this sensor for rapid enrofloxacin residue screening in complex food matrices.