<i>Ocimum tenuiflorum</i> Assisted Phyto‐Mediated Synthesis of ZnO/Chitosan/Polyvinylalcohol Nanocomposites: Enhanced Photocatalytic and Antibacterial Performance

ABSTRACT In this study, we report the phyto‐mediated green synthesis of zinc oxide nanoparticles using an aqueous extract of Ocimum tenuiflorum (a nontoxic leaf which decreases pain and swelling) followed by the incorporation into a chitosan/polyvinylalcohol matrix to form a nanocomposite. ZnO‐based nanocomposites were characterized by FT‐IR, XRD, SEM, HR‐TEM, UV‐DRS, and EDAX, confirming successful formation and integration of ZnO nanoparticles in the system. The average particle size is approximately 51 nm and the band gap observed in 2.1 eV. The nanocomposite exhibited enhanced photocatalytic dye degradation of methylene blue dye under sunlight of about 85%, following a pseudo‐first‐order kinetics with a rate constant of ca. 0.008 min −1 . Antibacterial tests against Escherichia coli (18 mm) and Staphylococcus aureus (21 mm) shows revealed superior inhibition zones for the ZnO/CS/PVA system together with a good biocompatibility at moderate concentrations that was validated using L929 cells via MTT assay with the IC 50 value of 72.02 µg/mL. These results demonstrated the potential of the biosynthesized cost‐effective nanocomposite as a sustainable and multifunctional material for environmental and biomedical applications.