Three birds with one stone: Integrated diagnosis and treatment platform for tetracycline based on Fe3O4QDs@ZIF-8 nanozyme.

Residues of tetracycline antibiotics pose a significant threat to the ecological environment and human safety, drawing widespread attention. In this study, a novel multifunctional nanozyme, Fe₃O₄QDs@ZIF-8, was synthesized by loading Fe₃O₄ quantum dots (QDs) onto zeolitic imidazolate framework-8 (ZIF-8) using a straightforward and mild co-precipitation method at room temperature. The nanozyme exhibited favorable peroxidase-like (POD-like) activities, with K_m values of 0.24 mM for TMB and 0.53 mM for H₂O₂, respectively. The inhibition of the POD-like activity of the nanozyme by tetracycline (TC) facilitated the development of a colorimetric and visual dual-modal detection system for TC, with detection limits of 0.015 mg/L and 0.12 mg/L, respectively. Furthermore, the nanozyme exhibited a porous structure similar to that of ZIF-8, with a specific surface area and pore diameter measured at 927.4 m²/g and 5.7 nm, respectively, resulting in an impressive adsorption capacity for TC of 1625.35 mg/g. Additionally, the band gap value of 4.16 eV indicates a strong photocatalytic oxidizing ability, enabling nearly complete degradation of the remaining TC after adsorption. The total removal efficiency of TC through adsorption and photocatalytic degradation reached 97.75 %. In the detection and remediation of TC in tap water and river water samples, Fe₃O₄QDs@ZIF-8 demonstrated superior sensitivity compared to high-performance liquid chromatography and exhibited a significantly higher removal efficiency than powdered activated carbon. A diagnostic and therapeutic integration platform for TC based on Fe₃O₄QDs@ZIF-8 has been successfully established. This platform integrates adsorption, detection, and photocatalytic degradation, providing a novel dual-mode detection and dual-procedure treatment for tetracycline antibiotic residues in the environment.