Biogenic synthesis of ZnO nanoparticles using Monsonia burkeana for use in photocatalytic, antibacterial and anticancer applications

The synthesis of metal oxide nanoparticles using plant extracts has become one of the alternative routes researchers use for the synthesis of nanomaterials. This is due to the high costs that are associated with nano particle preparation and the harsh solvents normally used as reducing agents. In this study, ZnO nanoparticles were synthesized from a Monsonia burkeana plant water extract and characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Laser Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectroscopy (UV-Vis). Laser Raman confirmed the formation of ZnO nanoparticles with the E-2 high phonon mode. UV-Vis and FTIR corroborated the formation of the ZnO nanoparticles with a characteristic ZnO peak at 325 nm and the ZnO peak identified in the finger print region (i.e. below 100 cm(-1)), respectively. FTIR further showed the introduction of the phytochemical functional groups from the Monsonia burkeana plant that were incorporated to the ZnO nanoparticles. TEM showed that the formed ZnO particles had a uniform and narrow size distribution between 5 nm and 45 nm with the dominant particles being less than 20 nm. The photocatalytic experiments showed that the ZnO nanoparticles actively degraded methylene blue dye. The Monsonia burkeana derived ZnO nanoparticles demonstrated antibacterial activity against both gram negative and positive bacterial strains, which could be attributed to their small particle sizes. Lastly, cytotoxicity tests showed that the ZnO nanoparticles had a growth inhibitory effect against A549 lung cancer cell lines. This study showed that these nanoparticles can be used in various biomedical applications.