Quasi-Diamond Platelet-Shaped Zinc Oxide Nanostructures Display Enhanced Antibacterial Activity

The current study compares the antibacterial activity of zinc oxide nanostructures (neZnO). For this purpose, two bacterial strains, Escherichia coli (ATCC 4157) and Staphylococcus aureus (ATCC 29213) were challenged in room light conditions with the aforementioned materials. Colloidal and hydrothermal methods were used to obtain the quasi-round and quasi-diamond platelet-shape nanostructures. Thus, the oxygen vacancy (VO) effects on the surface of neZnO are also considered to assess its effects on antibacterial activity. The neZnO characterization was achieved by X-ray diffraction (XRD), a selected area electron diffraction (SAED) and Raman spectroscopy. The microstructural effects were monitored by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Furthermore, optical absorption ultraviolet visible spectrophotometry (UV-Vis) and X-ray photoelectron spectroscopy (XPS) analyses complement the physical characterization of these nanostructures; neZnO caused 50 % inhibition (IC50) at concentrations from 0.064 to 0.072 mg/mL for S. aureus and from 0.083 to 0.104 mg/mL for E. coli, indicating an increase in activity against S. aureus compared to E. coli. Consequently, quasi-diamond platelet-shaped nanostructures (average particle size of 377.6 +/- 10 nm) showed enhanced antibacterial activity compared to quasi-round agglomerated particles (average size of 442.8 +/- 12 nm), regardless of Vo presence or absence. The quasi-diamond platelet-shaped ZnO (neZnO) nanostructures exhibited enhanced antibacterial activity against Escherichia coli (G-) and Staphylococcus aureus (G+) compared to the quasi-round particles. The morphology of the material plays an important or determining role in the antimicrobial activity, but not the enrichment of oxygen vacancies in neZnO.image

Automated summary

The current study compares the antibacterial activity of zinc oxide nanostructures. The quasi-diamond platelet-shaped nanostructures showed enhanced antibacterial activity compared to the quasi-round agglomerated particles. The morphology plays a crucial role in the antimicrobial activity, while the enrichment of oxygen vacancies does not have a significant effect.