Exploring the multifaceted potential of chitosan-capped silver nanoaprticles: Antioxidant, antimicrobial and antidiabetic properties

This study reports a green, room-temperature synthesis of silver nanoparticles (AgNPs) using Plantago major and Trifolium repens , followed by chitosan capping. Chitosan enhanced nanoparticle stability, reduced particle size, and improved biological activity. While previous work on these plant-mediated AgNPs has focused mainly on antibacterial effects, their antioxidant and antidiabetic potential—particularly in chitosan-capped forms—remains unexplored. Nanoparticle formation was confirmed by UV–visible spectroscopy, with XRD indicating crystallinity and SEM revealing predominantly spherical morphology. FTIR analysis identified functional groups involved in reduction and stabilization. Chitosan-capped AgNPs exhibited strong antioxidant activity across DPPH, ABTS, and hydrogen peroxide assays, with the highest scavenging observed in the hydrogen peroxide assay (up to ∼85% at 500 µg/mL). Antidiabetic activity, evaluated via α-amylase inhibition, showed moderate inhibition for P. major (up to 43.5%) and comparatively lower activity for T. repens . Antimicrobial activity assessed by disk diffusion demonstrated dose-dependent inhibition against both bacterial and fungal strains, with P. major -derived nanoparticles generally showing stronger effects. Overall, chitosan-capped AgNPs displayed enhanced antioxidant, antimicrobial, and antidiabetic activities, along with favorable physicochemical properties, highlighting their potential for biomedical applications.