Formation of ZnO Micro-Flowers Prepared via Solution Process and their Antibacterial Activity

Abstract

This paper presents the fabrication and characterization of zinc oxide micro-flowers and their antibacterial activity. The micro-flowers of zinc oxide composed of hexagonal nanorods have been prepared via solution process using precursor zinc acetate di-hydrate and sodium hydroxide in 3 h of refluxing time at ~90°C. The antibacterial activities of grown micro-flowers were investigated against four pathogenic bacteria namely S. aureus, E. coli, S. typhimurium and K. pneumoniae by taking five different concentrations (5-45 μg/ml) of ZnO micro-flowers (ZnO-MFs). Our investigation reveals that at lowest concentration of ZnO-MFs solution inhibiting the growth of microbial strain which was found to be 5 μg/ml for all the tested pathogens. Additionally, on the basis of morphological and chemical observations, a chemical reaction mechanism of ZnO-MFs composed of hexagonal nanorods was also proposed.

Figure 1

a shows the typical X-ray diffraction pattern of grown zinc oxide micro-flowers (ZnO-MFs) composed of hexagonal nanorods, b, c shows the low magnification and d shows the high magnification FESEM images of ZnO-MFs e shows the low magnification TEM image of ZnO-MFs and inset presents the SAED (selected area electron diffraction) pattern of grown ZnO nanorods whereas f presents the HR-TEM image and it shows that the lattice difference between two fringes is ~0.52 nm g presents the typical FTIR spectrum of grown ZnO-MFs

Figure 2

Bacterial growth curve of E. coli with increasing concentration of ZnO-MFs

Figure 3

Bacterial growth curve of K. pneumoniae with increasing concentration of ZnO-MFs

Figure 4

Bacterial growth curve of S. aureus with increasing concentration of ZnO-MFs

Figure 5

Bacterial growth curve of S. typhimurium with increasing concentration of ZnO-MFs

Figure 6

Typical Bio-TEM images of: aE. coli, b and inset ZnO-MFs with E. coli at different stages, cK. pneumoniae, d ZnO-MFs with K. pneumoniae

Figure 7

Typical Bio-TEM of: aS. typhimurium, bS. typhimurium with ZnO-MFs, cS. aureus and d ZnO-MFs with S. aureus