title: Cellular uptake and mutagenic potential of metal oxide nanoparticles in bacterial cells.
abstract: Extensive production and consumption of nanomaterials such as ZnO and TiO(2) has increased their release and disposal into the environment. The accumulation of nanoparticles (NPs) in ecosystem is likely to pose threat to non-specific targets such as bacteria. The present study explored the effect of ZnO and TiO(2) NPs in a model bacterium, Salmonella typhimurium. The uptake of ZnO and TiO(2) bare NPs in nano range without agglomeration was observed in S. typhimurium. TEM analysis demonstrated the internalization and uniform distribution of NPs inside the cells. Flow cytometry data also demonstrates that both ZnO and TiO(2) NPs were significantly internalized in the S. typhimurium cells in a concentration dependent manner. A significant increase in uptake was observed in the S. typhimurium treated even with 8 and 80 ng mL(-1) of ZnO and TiO(2) NPs with S9 after 60 min, possibly the formation of micelles or protein coat facilitated entry of NPs. These NPs exhibited weak mutagenic potential in S. typhimurium strains TA98, TA1537 and Escherichia coli (WP2uvrA) of Ames test underscoring the possible carcinogenic potential similar to certain mutagenic chemicals. Our study reiterates the need for re-evaluating environmental toxicity of ZnO and TiO(2) NPs presumably considered safe in environment.
authors.affiliation: Nanomaterial Toxicology Group, Indian Institute of Toxicology Research, Council of Scientific and Industrial Research (CSIR), Mahatma Gandhi Marg, P.O. Box 80, Lucknow 226 001, Uttar Pradesh, India.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Kumar
authors.forename: Alok K
authors.initials: AK
authors.lastname: Pandey
authors.forename: Shashi S
authors.initials: SS
authors.lastname: Singh
authors.forename: Rishi
authors.initials: R
authors.lastname: Shanker
authors.forename: Alok
authors.initials: A
authors.lastname: Dhawan
mesh_terms: D000818:Animals; D015169:Colony Count, Microbial; D004249:DNA Damage; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D008110:Liver Extracts / Q000737:chemistry; D050296:Microbial Viability / Q000187:drug effects; D009152:Mutagenicity Tests; D009153:Mutagens / Q000737:chemistry / Q000633:toxicity*; D053758:Nanoparticles; D010316:Particle Size; D017354:Point Mutation; D051381:Rats; D017208:Rats, Wistar; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D014025:Titanium / Q000737:chemistry / Q000633:toxicity*; D015034:Zinc Oxide / Q000737:chemistry / Q000633:toxicity*
chemical_list: D008110:Liver Extracts; D009153:Mutagens; C009495:titanium dioxide; D014025:Titanium; D015034:Zinc Oxide