Electron-bridge mediated Z-scheme nanozyme with homologous heterostructured MOF-on-MOF architectures for simultaneous colorimetric detection and removal of aflatoxin B1

Z-scheme nanozyme with homologous MOF-on-MOF architectures was prepared. • “Electron bridge” role of homologous Cu 2+ in boosting electron transfer. • Z-scheme structure suppressed electron–hole recombination. • POD-like activity was enhanced owing to homologous and Z-scheme structure. • Nanozyme enabled colorimetric detection and elimination of AFB 1 . Mycotoxins are typical contaminants produced by various fungal species, showing significant risks to human health due to their wide distributions and high carcinogenicity. Herein, the homologous heterostructured MOF-on-MOF nanozyme with Z -scheme structure were constructed via surface-initiated strategy by encapsulation of Cu-BDC on HKUST-1 for simultaneous colorimetric analysis and removal of aflatoxin B 1 (AFB 1 ). The homologous Cu 2+ ion plays a pivotal “electronic bridge” role in shortening the electron transfer distance between Cu-BDC and HKUST-1 and enhancing interfacial coupling. The recombination of intrinsic electrons and holes within HKUST-1@Cu-BDC can be suppressed owing to typical Z -scheme structure. These leads to a significant enhancement in peroxidase (POD)-like activity, as confirmed by advanced characterizations and density functional theory (DFT) calculations. Based on this enhanced homologous heterojunction, the indirect detection (HKUST-1@Cu-BDC/ssDNA biosensors) and direct removal (HKUST-1@Cu-BDC nanozyme) methods with limits of detection (LOD) of 0.87 μg/L and maximum removal rate of 79.6% for AFB 1 have been established. Finally, the homologous MOF-on-MOF nanozyme was successfully verified by both detection and removal process in complex food samples, while also demonstrating excellent repeatability and stability throughout the tests. This work provides a versatile strategy in designing and fabricating high-quality Z -scheme heterojunction nanozyme for mycotoxins governance. This study involved the development of an electron-bridge mediated Z -scheme nanozyme with homologous heterostructured MOF-on-MOF architectures (HKUST-1@Cu-BDC) via surface-initiated strategy by encapsulation of Cu-BDC on HKUST-1 for simultaneous colorimetric detection and removal of aflatoxin B 1 (AFB 1 ) two-in-one. Download: Download high-res image (174KB) Download: Download full-size image