Chitosan/Graphene Oxide/Ag Nanocomposites Loaded in Polyvinyl Alcohol Films as Biodegradable, UV-Blocking, and Antibacterial Film for Fruit Packaging

Abstract

The polyvinyl alcohol/chitosan/graphene oxide/Ag composite films are facilely fabricated as active multifunctional food packaging materials. The AgNPs of less than 10 nm immobilized onto CS/GO matrices are in situ synthesized by using NaBH₄ as a reductant. The effect of different amounts of Ag and CS:GO weight ratios on the mechanical properties, water resistance, optical properties, thermal stability, and antibacterial activities of various films are systematically investigated. The composite film obtained at 0.5 wt% AgNP loading and a CS:GO ratio of 5:1 demonstrates significantly improved tensile strength (33.07 MPa, 1.7 times higher), reduced water swelling (2.4 times lower), increased contact angle (71.08° vs. 53.54°), and enhanced thermal stability compared to the neat PVA film. Additionally, these composite films exhibit excellent bacterial killing and inhibition activities against Escherichia coli and Staphylococcus aureus , with zones of inhibition of 10.09 nm and 12.66 mm, respectively. Interestingly, no viable bacteria were found with the film-forming dispersion at 10 μg/mL. Furthermore, the fabricated films exhibit excellent UV-blocking effects, sufficiently protecting exposed green plums from UV damage for 10 days. The membrane-packed acerola fruits also demonstrate better freshness, slower ripening rate, and no signs of microbial growth as compared to those packed with commercial polyethylene film.