Active Eco-friendly Mucilage-Based Films Reinforced with Graphitic Carbon Nitride (g-C ₃ N ₄ ) for Sustainable Food Packaging Applications

Abstract

The increasing global reliance on plastic poses serious environmental and health risks, highlighting the need for biodegradable packaging alternatives. Opuntia ficus-indica mucilage (OFIM) is a promising biopolymer due to its abundance and biodegradability, although its poor mechanical and barrier properties limit direct application. In this study, OFIM-based films reinforced with cellulose nanofibers (CNF) and graphitic carbon nitride (g-C3N4) nanoparticles at 1%, 3%, and 5% were developed for food packaging applications. The g-C3N4 nanoparticles and OFIM/CNF/g-C3N4 composite films were characterized using UV–vis spectroscopy, XRD, and FTIR, confirming successful nanoparticle synthesis and incorporation into the biopolymer matrix. The nanocomposite films exhibited significantly improved physicochemical, mechanical, optical, and biological properties (p < 0.05). Increasing g-C3N4 concentration reduced moisture content, solubility, and water vapor permeability while enhancing tensile strength, thickness, and UV-blocking capacity, with optimal overall performance at 5% g-C3N4. Antioxidant activity increased with nanoparticle concentration, as demonstrated by ABTS radical scavenging assays. Antimicrobial evaluation against Enterococcus faecalis, Escherichia coli, and Staphylococcus aureus revealed enhanced inhibition, particularly at 3% g-C3N4, attributed to improved nanoparticle dispersion and bioactive compounds in OFIM. Overall, the OFIM/CNF/g-C3N4 nanocomposite films show strong potential as sustainable active food packaging materials, supporting reduced plastic use and postharvest losses in line with the Sustainable Development Goals.