Laurus nobilis leaf extract mediated green synthesis of ZnO nanoparticles: Characterization and biomedical applications.

The present study reports the green synthesis of zinc oxide nanoparticles using the aqueous leaf extract of Laurus nobilis ( Ln -ZnO NPs) by co-precipitation method. The synthesized Ln -ZnO NPs were characterized by UV–Vis spectroscopy, FTIR, XRD, TEM, SEM and EDX. Ln -ZnO NPs were crystalline in nature, flower like and have hexagonal wurtzite structure with a mean particle size of 47.27 nm. The antibacterial activity of Ln -ZnO NPs was greater against Gram positive ( Staphylococcus aureus) bacteria than Gram negative ( Pseudomonas aeruginosa) bacteria. The zone of inhibition against S. aureus was 11.4, 12.6 and 14.2 mm at 25, 50 and 75 μg mL −1 . The zone of inhibition against P. aeruginosa was 9.8, 10.2 and 11.3 mm at 25, 50 and 75 μg mL −1 . The light and confocal laser scanning microscopic images evidenced that Ln -ZnO NPs effectively inhibited the biofilm growth of S. aureus and P. aeruginosa at 75 μg mL −1 . The cytotoxicity studies revealed that Ln -ZnO NPs showed no effect on normal murine RAW264.7 macrophage cells. On the other hand, Ln -ZnO NPs were effective in inhibiting the viability of human A549 lung cancer cells at higher concentrations of 80 μg mL −1 . The morphological changes in the Ln -ZnO NPs treated A549 lung cancer cells were observed under phase contrast microscope. [ABSTRACT FROM AUTHOR]