Metal-Organic Framework@Polysulfone Composite Beads for Air Filtration of Postharvest Pathogenic Fungal Spores

Phytopathogenic fungal infections pose a persistent threat to postharvest fruit quality and food security worldwide, with resistant strains increasingly limiting the efficacy of conventional fungicides. This study explored metal-organic frameworks (MOFs) as an emerging class of antifungal materials and examined their potential for air-based decontamination in storage environments. Among the zinc- and copper-based frameworks tested, HKUST-1 and ZIF-8 demonstrated exceptionally broad-spectrum antifungal activity, completely inhibiting mycelial growth of Penicillium expansum, Penicillium citrinum, and Colletotrichum gloeosporioides, while maintaining strong inhibition of Botrytis cinerea and Mucor piriformis. To enable practical deployment, the most active MOFs were incorporated into polysulfone composite beads via phase inversion, preserving their antifungal properties while offering a processable and scalable format. In vitro assays revealed that these MOF@PSF beads substantially suppressed both mycelial growth and spore germination, with HKUST-1@PSF and ZIF-8@PSF composites reducing conidial viability to near-complete levels. Mechanistic studies revealed that HKUST-1 primarily acts through substantial copper ion release (≈19 ppm), leading to pronounced metabolic inhibition, whereas ZIF-8 operates via reactive oxygen species (ROS) generation. Evaluation in a dual-chamber air-filtration prototype demonstrated remarkable performance: both composites reduced airborne spore transfer by 95.2-96.7% for P. expansum and by 99.4-99.6% for B. cinerea, effectively preventing contamination of the clean chamber and protecting the stored produce. These findings establish MOF@PSF composite beads as bioactive filtration materials that combine physical spore capture with intrinsic antifungal action, offering a residue-free route to limiting fungal dissemination during postharvest storage.