title: Genotoxicity and cytotoxicity of ZnO and Al2O3 nanoparticles.
abstract: OBJECTIVE
  Metal oxide nanoparticles (ZnO-NPs and Al2O3-NPs) are used in many fields, including consumer products and biomedical applications. As a result, exposure to these NPs is highly frequent, however, no conclusive information on their potential cytotoxicity and genotoxicity mechanisms are available. For this reason, we studied cytotoxic and genotoxic effects of ZnO-NPs and Al2O3-NPs on human peripheral blood lymphocytes.
  
  
  METHODS
  We obtained our goals by using MTT assay, Annexin V-FITC flow cytometry, and alkaline, neural and pH 12.1 versions of comet assay.
  
  
  RESULTS
  Exposure of lymphocytes to both NPs for 24 h slightly decreased viability of lymphocytes at ≥ 0.5 mM. For the first time, we revealed using the comet assays that both ZnO-NPs and Al2O3-NPs caused a concentration-dependent increase of DNA single-strand breaks, but not alkali-labile sites. Treatment with DNA glycosylases showed that the NPs induced oxidative DNA damage. DNA damage caused by both nanoparticles at 0.05 mM was removed within 120 min, however lymphocytes did not repair DNA damage induced by 0.5 mM NPs. Studied nanoparticles did not induce apoptosis in lymphocytes.
  
  
  CONCLUSIONS
  Our results suggest that ZnO-NPs and Al2O3-NPs at concentration up to 0.5 mM did not exhibit cytotoxic effect but may exert genotoxic effect on lymphocytes, at least partially by the generation of oxidative DNA damage and strand breaks.
authors.affiliation: Department of Internal Disease, Diabetology and Clinical Pharmacology, Medical University of Lodz , Lodz , Poland .
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Sliwinska
authors.forename: Dominik
authors.initials: D
authors.lastname: Kwiatkowski
authors.forename: Piotr
authors.initials: P
authors.lastname: Czarny
authors.forename: Justyna
authors.initials: J
authors.lastname: Milczarek
authors.forename: Monika
authors.initials: M
authors.lastname: Toma
authors.forename: Anna
authors.initials: A
authors.lastname: Korycinska
authors.forename: Janusz
authors.initials: J
authors.lastname: Szemraj
authors.forename: Tomasz
authors.initials: T
authors.lastname: Sliwinski
mesh_terms: D000328:Adult; D000537:Aluminum Oxide / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D020552:Comet Assay; D003257:Consumer Product Safety; D053904:DNA Breaks, Single-Stranded; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects; D016503:Drug Delivery Systems; D006801:Humans; D007700:Kinetics; D008214:Lymphocytes / Q000187:drug effects*; D053768:Metal Nanoparticles / Q000633:toxicity*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D018675:Toxicity Tests; D055815:Young Adult; D015034:Zinc Oxide / Q000633:toxicity*
chemical_list: D000537:Aluminum Oxide; D015034:Zinc Oxide
keywords: DNA repair; oxidative DNA damage; single and double strand breaks