Plasmon-Enhanced ZnO/Ag Nanoparticles with Synergistic Antibacterial and Anticancer Activities

Plasmonic nanomaterials have garnered significant attention for their enhanced optical, antibacterial, and anticancer proper ties, owing to their surface plasmon resonance (SPR) effects. In this study, ZnO and ZnO/Ag nanoparticles were synthesized using green synthesis approach. The structural, morphological, and physicochemical properties of the fabricated nanomateri als were systematically characterized via X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), trans mission electron microscopy (TEM), and dynamic light scattering (DLS). XRD analysis confirmed the hexagonal wurtzite structure of ZnO, while additional peaks in ZnO/Ag nanoparticles indicated successful silver incorporation. TEM imaging revealed a spherical morphology with average particle sizes of 35 ± 10 nm for ZnO and 55 ± 10 nm for ZnO/Ag. The anti bacterial activity of the nanoparticles was assessed against Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Streptococcus mutans, Staphylococcus aureus, and Enterococcus faecalis using broth microdilution method. ZnO/Ag nanoparticles exhibited superior antibacterial efficacy, particularly against Gram-negative strains, due to the synergistic action of ZnO-mediated oxidative stress and Ag⁺-induced membrane disruption. The plasmonic properties of Ag further contributed to the antibacterial effect by enhancing reactive oxygen species (ROS) generation under light exposure. Moreover, the MTT assay demonstrated a dose-dependent cytotoxic effect on A-549 lung carcinoma cells, with ZnO/Ag nanoparticles displaying a lower IC50 than ZnO. The enhanced anticancer activity was attributed to increased mitochondrial dysfunction, ROS genera tion, and apoptosis induction, further amplified by plasmonic interactions. These findings highlight the potential of ZnO/Ag nanomaterials as promising candidates for biomedical applications, particularly in antimicrobial and anticancer therapies.