Fabrication, growth mechanism and antibacterial activity of ZnO micro-spheres prepared via solution process

This paper presents the high antibacterial activity of ZnO micro-spheres prepared via solution process using zinc nitrate hexahydrate, (+) l-cysteine, HMT and sodium hydroxide against four pathogenic bacteria Staphylococcus aureus, Escherichia coli, Salmonella typhimurium and Klebsiella pneumoniae. The antibacterial activity of ZnO micro-spheres was studied via nutrient broth medium at different concentrations (5μg/ml–45μg/ml) of ZnO micro-spheres. Our investigation reveals that the lowest concentration of micro-spheres solution inhibits the growth of microbial strain, which was found to be 5μg/ml for S. aureus, S. typhimurium and K. pneumoniae whereas for E. coli, it was calculated to be 15μg/ml. The diameter of each micro-sphere lie between 2 and 3μm as observed from FESEM and Transmission electron microscopy. The composition of synthesized material was analyzed by FTIR spectroscopy and it shows the band of ZnO at 462cm−1. Additionally, on the basis of morphological and chemical observations the growth mechanism of ZnO micro-spheres was also proposed. ► ZnO micro-sphere shows high antibacterial activity against pathogenic bacteria. ► The micro-spheres (5μg/ml–45μg/ml) inhibit the growth of four microbial strains. ► The micro-sphere lie between 2–3μm composed with small (∼20nm) nanoparticles.