Crosslinked-AuNPs@CD-MOF Incorporated into PLA-Zein Composite Film with Humidity-Responsive Antimicrobial Release for...

Foodborne pathogens cause hundreds of millions of illnesses annually, underscoring the urgent need for advanced antimicrobial food packaging materials. The objective of this study was to develop a crosslinked cyclodextrin metal-organic framework, loaded with gold nanoparticles (CL-AuNPs@CD-MOF) and integrated into a PLA-Zein composite film with humidity-responsive antimicrobial release, as a sustainable and high-performance packaging solution to address the critical limitations of conventional materials in controlling microbial contamination during food storage. Therefore, gold nanoparticles (AuNPs) were synthesized via a green approach using CD-MOFs as stabilizers and p-coumaric acid as a natural reducing agent, then crosslinked with diphenyl carbonate (DPC) to produce CL-AuNPs@CD-MOF. Crosslinking conditions were optimized to a CD-MOF:DPC ratio of 1:1, 1080 min reaction time, and 80 °C, preserving the cubic morphology and crystalline structure while transforming burst release into sustained antimicrobial activity against E. coli and S. aureus over 7 days. Then, the incorporation of CL-AuNPs@CD-MOF into PLA-Zein films yielded a composite packaging material with favorable mechanical and barrier properties, including a water vapor transmission rate of 539.44 g/m²·24 h and an oxygen permeability of 235.90 cm³/m²·24 h·0.1 MPa. Progressive elimination of E. coli, S. aureus, and L. monocytogenes over 7 days was confirmed, with antimicrobial efficacy originating exclusively from the CL-AuNPs@CD-MOF component. Application on Agaricus bisporus over 12 days of refrigerated storage demonstrated superior preservation performance: mushrooms inoculated with L. monocytogenes and packaged with CL-AuNPs@CD-MOF/PLA-Zein exhibited a weight loss of only 6.20 ± 2.06%, compared to 17.74 ± 3.15% for PLA-Zein and 41.50 ± 3.01% for PE controls. Color stability was equally improved, with lightness values of 71.46 ± 1.47 retained under CL-AuNPs@CD-MOF/PLA-Zein packaging, versus 58.37 ± 0.86 for PLA-Zein and 23.34 ± 2.34 for PE. Mushrooms inoculated with E. coli and S. aureus followed consistent trends. These results establish CL-AuNPs@CD-MOF/PLA-Zein as a promising multifunctional antimicrobial packaging platform for sustainable food preservation.