title: Antimicrobial activity of zinc oxide (ZnO) nanoparticle against Klebsiella pneumoniae.
abstract: BACKGROUND
  Zinc oxide nanoparticles (ZnO Nps) have potential application in piezoelectric nanogenerator and in biotechnology.
  
  
  OBJECTIVE
  The antibacterial activity of ZnO Nps on Klebsiella pneumoniae (ATCC 70068) and mode of action of ZnO Nps was investigated.
  
  
  METHODS
  ZnO Nps was synthesized by a precipitation method and characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. In vitro susceptibility of K. pnumoniae of the ZnO Nps was detected using the disk diffusion method, and the minimum inhibitory concentration (MIC) value was determined using the serial dilution method. The chemical and physical interaction between the cell envelope of K. pneumonia and ZnO Nps was investigated. The effect of ZnO Nps on the cytotoxic activities of K. pneumonia was investigated using a HEp-2 cell line.
  
  
  RESULTS
  The MIC of ZnO Nps was found in 40 µg/ml. The standard growth curve showed that ZnO Nps of 0.75 mM inhibited K. pneumoniae after 4 h. The interaction with outer membrane protein (OMP) and lipoploysacharride (LPS) residues showed modulation in ∼66 kDa and ∼29 kDa proteins with the use of increasing concentrations of ZnO Nps. The amount of nucleic acid and protein released from the cells increased with the ZnO Nps concentration used. Importantly, the OD of the ZnO Nps-treated cells decreased within 30 min of incubation in the presence of SDS. ZnO Nps-treated K. pneumoniae were five-fold less infectious in the HEp-2 cell line at doses between 0.50 and 0.75 mM.
  
  
  CONCLUSIONS
  These results suggest the potential antibacterial use of ZnO Nps against K. pneumoniae infections.
authors.affiliation: Department of Biotechnology, Sathyabama University , Chennai, Tamil Nadu , India.
authors.forename: Lanka Shalini
authors.initials: LS
authors.lastname: Reddy
authors.forename: Mary Magar
authors.initials: MM
authors.lastname: Nisha
authors.forename: Mary
authors.initials: M
authors.lastname: Joice
authors.forename: P N
authors.initials: PN
authors.lastname: Shilpa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000502:physiology; D053768:Metal Nanoparticles; D008826:Microbial Sensitivity Tests / Q000379:methods; D015034:Zinc Oxide / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D015034:Zinc Oxide
keywords: Agar diffusion assay; HEp-2 cells; growth curve; lipoploysaccharride; metal oxide nanoparticle; minimum inhibitory concentration; outer membrane protein