Metal-Organic Framework (MOF)-Based Fluorescent Sensing Platforms for Agri-Food Quality and Safety: Mechanisms and Applications

The global increase in agri-food demand points to a strong need for rapid, sensitive, and accurate contaminant detection methods. Metal-organic frameworks (MOFs), with remarkable structural tunability, high surface areas, and well-defined porous structures, have shown great potential as fluorescent sensing platforms. In the context of fundamental emission mechanisms and key photophysical processes, this review provides a systematic survey of recent literature (mainly from 2020– 2025) on MOF-based fluorescent sensors, focusing on the intrinsic fluorescence pathways such as metal-centered, ligand-centered, and guests-induced luminescence, and further differentiates their unique fluorescence properties in solid- and wet-state. The literature suggests that both lattice rigidity and AIE effects can enhance quantum yields to near unity. Specific guest-host interactions, along with defined exciton migration pathways, enable ultra-sensitive detection at trace levels (nmol to pmol) of various contaminants, e.g., pesticides, veterinary drug residues, mycotoxins, unauthorized additives, metal ions, and indicators of food spoilage. An in-depth assessment of recent approaches, including nanoparticle integration, ligand functionalization, dual-emission (ratiometric) schemes, and smartphone-based, easily portable sensing, demonstrates significant improvements in sensitivity, selectivity, operational stability, and real-world feasibility. Nevertheless, issues such as the stability of MOFs in complex environments, sensor multi-functionality, scalability, and cost-effectiveness still need to be addressed. Novel methodologies combining AI/ML methods are emerging and hold great potential, providing pathways to adaptive, self-calibrating, and multiplexed MOF-based sensing systems. Taken together, this review summarizes key lessons from recent work that demonstrate both exciting advances and challenges, and outlines a perspective on the development and application of MOF-based fluorescent sensors that can have a transformative impact on agri-food safety, public health, and environmental sustainability.