Chitosan nanocomposite films with metal nanoparticles: Synthesis, antimicrobial mechanisms and applications in...

Chitosan (CS) based nanocomposite films incorporating metal nanoparticles (MNPs) have emerged as a rapidly advancing field in active and sustainable food packaging. This review critically summarizes recent progress on the integration of silver nanoparticles (AgNPs), zinc oxide nanoparticles (ZnONPs) and copper nanoparticles (CuNPs) into CS matrices, highlighting how these systems address the inherent limitations of pristine CS films, such as poor mechanical strength, moisture sensitivity and limited antimicrobial efficacy. We discuss underlying antimicrobial mechanisms including reactive oxygen species generation, ion release, DNA/protein interactions and membrane disruption while emphasizing the synergistic role of CS's polycationic structure. Applications across meat, poultry, dairy, fruits, vegetables, bakery products and seafood demonstrate consistent improvements in microbial inhibition and shelf-life extension. Comparative insights are provided on the functional enhancements (mechanical, barrier, UV-blocking, antioxidant) achieved with different nanoparticles and hybrid systems (Ag/ZnO, ZnO/CuO), alongside considerations of nanoparticle migration, biodegradability, safety and regulatory challenges. By consolidating mechanistic knowledge with application case studies, this review identifies critical gaps in scalability, safety validation and regulatory acceptance. Future directions highlight the promise of eco-friendly synthesis, hybrid multifunctional systems and intelligent packaging technologies. Overall, CS-MNP nanocomposites represent a transformative platform for replacing petroleum-based plastics and advancing sustainable food protection.