Eco-friendly Bi₂O₃ nanocomposite films based on cellulose acetate and carboxymethyl cellulose: A bioinspired approach for antimicrobial and biocompatible materials.

The development of eco-friendly biomaterials with antimicrobial and biocompatible properties is critical for biomedical and environmental applications. In this study, bismuth oxide nanoparticles (Bi₂O₃NPs) were synthesized via a green approach using Moringa oleifera leaf extract as a natural reducing and stabilizing agent, and subsequently incorporated into cellulose acetate (CA), carboxymethyl cellulose (CMC), and hybrid CMC@CA polymer matrices. The nanocomposite films were systematically characterized by XRD, FTIR, TEM, and XPS, confirming the formation of monoclinic α-Bi₂O₃ with uniform dispersion within the polymer networks. Biological evaluation demonstrated that the CMC@CA-Bi₂O₃ hybrid film exhibited the strongest antimicrobial activity, achieving inhibition percentages of up to 93 % against Candida albicans and over 90 % against Escherichia coli, surpassing some reference antibiotics. Cytocompatibility testing on L929 and Wi38 fibroblasts revealed cell viability above 70 % at the highest tested concentrations, confirming biosafety. The enhanced activity of the hybrid system is attributed to synergistic effects between hydrophilic and hydrophobic domains that promoted nanoparticle dispersion and stability. These findings highlight the potential of CMC@CA-Bi₂O₃ nanocomposites as promising bioinspired materials for antimicrobial coatings and biomedical applications. Future studies will focus on detailed mechanistic validation, extended toxicological profiling, and environmental assessments to fully substantiate their eco-friendly potential.