Development of antioxidant and antimicrobial chitosan nanocomposite films incorporating with eco-friendly silver nanoparticles synthesized with Arabic gum

In this study, silver nanoparticles (AgNPs) were synthesized via an eco-friendly method using Arabic gum extract, with particle sizes ranging from 32 to 141 nm depending on the volume of extract used (1–10 mL). Zeta potential measurements confirmed negative surface charges across all samples, indicating good colloidal stability. UV–VIS analysis showed a surface plasmon resonance peak around 450 nm, confirming nanoparticle formation. Among the synthesized AgNPs, those with a 32 nm diameter exhibited the highest antioxidant activity (71.22%) in DPPH assays. These were incorporated into chitosan films at concentrations of 0, 0.1, 0.2, and 0.3 mM via solvent casting. FTIR analysis identified functional groups such as CO stretching (primary amide), NH₂ (secondary amide), CN (tertiary amide), and COC linkages. SEM, EDX, and XRD confirmed the spherical morphology and successful integration of AgNPs. Antioxidant activity increased with nanoparticle content, reaching up to 96% for films with 0.3 mM AgNPs. Only AgNP-doped films exhibited antibacterial activity, with inhibition zones (mm) against B. subtilis (9–11.5), S. aureus (10.5–11.5), P. aeruginosa (10–12), and E. faecalis (11.5–12.5), while no inhibition was observed for E. coli, K. pneumoniae, or C. albicans. These results demonstrate the potential of green-synthesized AgNPs as functional additives in biopolymer films with enhanced antioxidant and antibacterial properties, suitable for applications in food packaging, medical devices, and surface hygiene, offering a sustainable alternative to conventional antimicrobial agents.