Dual-functional Z‑scheme heterojunction nanozymes with surface encapsulation of porphyrin-based metal-organic framework on covalent organic framework for integrated detection and removal of aflatoxin B(1) in foods.

内容摘要

Aflatoxin B1 (AFB1) contamination poses a serious threat to food safety and environmental health, thus making an active area of research in development of efficient detection and removal strategies. Herein, the Z‑scheme heterojunction nanozyme with high peroxidase (POD)‑like activity was constructed by growing porphyrin‑based metal‑organic framework (TCPP‑Fe) on the surface of covalent organic framework (TATP) for simultaneous detection and efficient removal of AFB1 in foods. The enhanced POD-like activity of TATP/TCPP‑Fe composite can be attributed to the promoted interfacial charge transfer within heterojunction. The steady-state kinetic parameters of Km can reach 0.21 and 0.24 mmol/L for hydrogen peroxide (H2O2) and 3,3',5,5'-tetramethylbenzidine (TMB) calculated by Michaelis-Menten equation. The detailed catalytic process of reactive oxygen species (ROS) generated and the specific catalytic mechanism of inter charge transfer within TATP/TCPP‑Fe are proposed. The direct detection and removal method for AFB1 was established based on the strong oxidizing ability of the generated ROS, including hydroxyl radicals (•OH) and superoxide anions (•O2-). The low detection limit (LOD) of 0.34 μg/L and high removal rate of 99.8% can be reached with the TATP/TCPP‑Fe composite. This integrated detection and removal strategy was successfully applied to real dried fruit samples, demonstrating its potential for on‑site monitoring and green remediation of AFB1 contamination in food and environmental matrices.