| Bacterial and fungal infections have become the main problems causing food contamination and endangering food safety.Foodborne pathogenic bacteria deposited on the food contact surface will also cause the growth of biofilm,and these biofilms also caused serious problems to various food packaging materials,greatly harming people’s lives and production.As a result,there is an urgent need for effective and long-term active treatment methods to eradicate foodborne pathogenic bacteria and its biofilm.Due to its plasma resonance effect（SPR）,silver nanoparticles（Ag NPs）exhibit effective photocatalytic activity in the visible range.Silver halide,a photosensitive substance,can significantly increase the photocatalytic activity of nano-silver.Ag@Ag Cl It has demonstrated strong photocatalytic activity and stability as a novel visible light-mediated plasma photocatalytic antibacterial agent.Chitosan（CS）,a polycationic biopolymer with high antibacterial activity and a strong affinity for metal ions,can be used as a proppant to prevent agglomeration during the growth of nanoparticles and prevent the leakage of nanoparticles.Inorganic nanomaterials can also be incorporated into biopolymers to improve the antibacterial properties and mechanical strength of chitosan,meet the application of food packaging materials,and effectively prevent bacterial fungi from contaminating food.This study synthesizes silver-based nanoparticles with various structural variations,embeds them on chitosan films,creates nanocomposite films with strong stability and high photocatalytic activity,discusses the bactericidal effects of nanomaterials on bacteria and fungi,and uses nanocomposite films for food packaging.The details are as follows:1.By examining the preparation methods for silver-based nanomaterials with various morphologies,various types of silver-based nanomaterials were created in various reaction systems,and the impact of these systems on the morphology of the resulting nanomaterials was discussed.Scanning electron microscopy,Fourier infrared spectroscopy,ultraviolet-visible spectroscopy,X-ray powder diffraction,and X-ray photoelectron spectroscopy were used to characterize the nanomaterials.The outcomes demonstrate the regular shape and strong photocatalytic absorption activity of the produced nanoparticles.The chitosan film was used to create the silver-based nanocomposite film,and by dispersing the nanoparticles evenly throughout the chitosan film,the chitosan film’s photocatalytic activity was significantly increased.2.By examining the potential applications of silver-based nanomaterials in bio-antibacterial processes.The effectiveness of nanomaterials and nanocomposite films in eliminating both free bacteria and bacterial biofilm was investigated.Furthermore,the potential of nanocomposite films in preserving chicken meat and their suitability for use as food packaging material were explored.The findings indicate that both nano-Ag@Ag Cl and composite films possess notable antibacterial properties and can effectively eliminate 99.9%of bacteria and eliminate biocoatings within a duration of 20 minutes under light.These results lay a solid foundation for further application of silver-based nanomaterials and pave the way for future research into the development of antibacterial nanomaterials with photocatalytic activity in the field of food packaging.3.To ensure the safety and viability of nanocomposite film as a means of food packaging,an investigation was conducted into the antifungal properties of CS-Ag@Ag Cl composite film against common fungi.The resulting CS-Ag@Ag Cl film was then utilized to package grapes and loquats in order to prevent microbial infection and extend their shelf life.The findings indicated that due to the stability of Ag@Ag Cl NPs and their incorporation into chitosan,visible light irradiation had a profound effect in exterminating microorganisms responsible for food spoilage.The nanocomposite films exhibited remarkable potential in preserving fruit and inhibiting fungal growth,successfully eradicating 96%of fungi following120 minutes of visible light exposure.This presents a novel avenue for the application of silver nanoparticles in food packaging.4.The product’s photocatalytic activity and stability were assessed via a methyl orange photocatalytic degradation experiment.In addition,we demonstrated that Ag@Ag Cl nanomaterials can produce highly cytotoxic reactive chlorine radicals（RCS）by in situ oxidation under visible light irradiation to mediate damage to bacteria and fungi,and the concentration of Cl·radicals produced by Ag@Ag Cl NPs(10μg m L-1,10 m L)for 10 min is7.88 m M by exposure to visible light（λ>400 nm）. |
