Green Fabrication of Alginate–Silver Nanocomposite Hydrogel Using Premna serratifolia Leaf Extract: Characterization, Comparative Evaluation, and Enhanced Antimicrobial Efficacy”

The present study reports the green fabrication of a sustainable alginate–silver nanocomposite hydrogel (Alg–AgNC) employing the aqueous leaf extract of Premna serratifolia L. as a natural reducing and stabilizing agent. The eco-friendly route enables in-situ formation of silver nanoparticles (AgNPs) within a sodium-alginate matrix, eliminating the need for chemical cross-linkers or toxic precursors. The developed nanocomposite was characterized using UV–Vis spectroscopy, FTIR, XRD, SEM, TEM, and zeta-potential analysis. Comparative assessments between biogenic AgNPs and the Alg–AgNC hydrogel evaluated improvements in physicochemical stability, structural integrity, and antimicrobial performance. The Alg–AgNC hydrogel exhibited a surface-plasmon resonance at 428 nm, characteristic Ag (111) reflections in XRD, and uniformly dispersed nanoparticles (20–40 nm) embedded within the alginate network. The zeta potential (–32 mV) and FTIR spectra confirmed enhanced colloidal stability and effective phytochemical capping. Antibacterial testing against Escherichia coli and Staphylococcus aureus revealed a 1.5–2-fold increase in inhibition-zone diameter compared with free AgNPs, attributed to sustained Ag⁺ release and synergistic polymer–phytochemical interactions. The composite hydrogel remained stable for over 30 days without aggregation, demonstrating mechanical robustness and reusability. This study presents the first report of an alginate–silver nanocomposite hydrogel synthesized using Premna serratifolia leaf extract , offering a superior, biocompatible, and sustainable nanomaterial platform for biomedical and environmental applications (1–3, 5, 7–10).