A scalable microfluidic-blow-spinning platform for fabricating food-grade γ-cyclodextrin metal–organic-framework nanofiber composites with sustained release of thymol: a preservation case study of fresh-cut fruits

Introduction Developing advanced functional composites by integrating metal–organic frameworks (MOFs) with polymeric nanofibers are important research in materials science. This strategy of incorporating MOFs into polymeric nanofibers offers a promising route to fabricate multifunctional materials with controlled release and antimicrobial capabilities. However, most existing MOFs are metal-based, which poses potential metal ion leaching risks in food-contact scenarios; besides, achieving uniform MOF dispersion in polymeric matrices and enabling scalable fabrication of such composite nanofibers remain challenges. Objectives The present study aimed to develop a novel and scalable fabrication platform for food-grade MOF-nanofiber composites by integrating γ-cyclodextrin metal–organic frameworks (γ-CD-MOFs) with rapid microfluidic-blow-spinning (MBS). Methods γ-CD-MOF was synthesized using γ-cyclodextrin as a biomolecular ligand, followed by adsorption of thymol (THY) through electrostatic interactions. Molecular docking was conducted to elucidate the encapsulation and stabilization mechanisms. The THY-loaded γ-CD-MOF was incorporated into polycaprolactone (PCL) nanofibers via MBS to produce THY@γ-CD-MOF/PCL nanofiber films. Their physicochemical properties, mechanical performance, sustain release behavior, antimicrobial activity, biocompatibility, and preservation efficacy in fresh-cut fruits were evaluated. Results γ-CD-MOF achieved 78.3 % THY encapsulation. Docking revealed hydrogen bonding between the phenolic hydroxyl group of THY and hydroxyl groups of dual γ-CD units (1.781 Å), shorter than typical hydrogen bonds (∼3.5 Å), contributing to complex stability. MOFs were well-dispersed, and their incorporation enhanced the thermal stability, mechanical strength, and hydrophilicity of the nanofibers. The nanofiber films exhibited broad-spectrum antimicrobial activity, sustained THY release at 4 °C and 25°C, and good biocompatibility, effectively suppressing browning and firmness loss in fresh-cut apples. Conclusion The MBS-based platform enabled efficient fabrication of active food-grade γ-CD-MOF-loaded nanofiber preservation materials. THY encapsulation via hydrogen bonding and hydrophobic interactions provided sustained release and antimicrobial functionality, significantly extending the freshness of fresh-cut apples.