Metal-Organic Framework fluorescent sensors for volatile and biogenic amines: from molecular design to intelligent real-time detection

Volatile and biogenic amines are important indicators of environmental pollution and food spoilage. Sensitive and selective detection of them is crucial for environmental monitoring and food safety. Fluorescence sensors based on metal-organic frameworks (MOFs) have become an important platform for amine detection due to their tunable channels, functional sites, and controllable electron/energy transfer characteristics. This review summarizes three sensing modes-quenching type, activation type and ratiometric, and focuses on elaborating the roles of photoinduced electron transfer (PET), aggregation-induced emission (AIE), excited-state intramolecular proton transfer (ESIPT), and metal-to-ligand/ligand-to-metal charge transfer (MLCT/LMCT) mechanisms in amine-responsive fluorescence. Material engineering strategies, including dye encapsulation, quantum dot composite and metal nanocluster loading, can achieve dual-emission, ratiometric and multi-mode sensing, and enhance their sensitivity and visualization capabilities. These sensors have been applied to the detection of amines in air, water and food substrates. In the future, in-depth research on multi-mode sensing, analysis based on smart phones and deep learning is expected to promote the development of MOF-based systems in the fields of food safety and environmental monitoring toward portable, intelligent and on-site detection applications.