Green-synthesized silver nanoparticles immobilized on graphene oxide for fruit preservation in alginate films

In this study, silver nanoparticles were synthesized by redox method using tea polyphenol as a reducing agent. These nanoparticles were then immobilized within sodium alginate (SA) composite films using graphene oxide (Go), resulting in films with enhanced food preservation capabilities. Initially, the synthesized silver nanoparticles underwent characterization through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). This characterization affirmed the successful synthesis of silver nanoparticles. Subsequently, the impact of silver nanoparticles and graphene oxide on the properties of the SA composite films was investigated. The SA composite films were analyzed barrier, mechanical, thermal stability, and functional properties. The findings revealed that the inclusion of silver nanoparticles immobilized in Go augmented the tensile strength (23.6 %), degradation temperature of the films, reduced water vapor permeability, and exhibited antioxidant properties (4.16 %-42.09 %), and antimicrobial activities against Escherichia coli and Staphylococcus aureus (19.79-20.37 times). The graphene oxide immobilizes the silver nanoparticles, thereby reducing the release concentration. Packaging blueberry fruits with the SA composite film impregnated with Go-immobilized silver nanoparticles reduced weight loss and wrinkle index and this enhanced blueberry fruit shelf life. Thus, this work presents a novel approach to preparing antimicrobial packaging films for post-harvest fruit preservation.