title: Toxicity of TiO2 nanoparticles to Escherichia coli: effects of particle size, crystal phase and water chemistry.
abstract: Controversial and inconsistent results on the eco-toxicity of TiO2 nanoparticles (NPs) are commonly found in recorded studies and more experimental works are therefore warranted to elucidate the nanotoxicity and its underlying precise mechanisms. Toxicities of five types of TiO2 NPs with different particle sizes (10∼50 nm) and crystal phases were investigated using Escherichia coli as a test organism. The effect of water chemistry on the nanotoxicity was also examined. The antibacterial effects of TiO2 NPs as revealed by dose-effect experiments decreased with increasing particle size and rutile content of the TiO2 NPs. More bacteria could survive at higher solution pH (5.0-10.0) and ionic strength (50-200 mg L(-1) NaCl) as affected by the anatase TiO2 NPs. The TiO2 NPs with anatase crystal structure and smaller particle size produced higher content of intracellular reactive oxygen species and malondialdehyde, in line with their greater antibacterial effect. Transmission electron microscopic observations showed the concentration buildup of the anatase TiO2 NPs especially those with smaller particle sizes on the cell surfaces, leading to membrane damage and internalization. These research results will shed new light on the understanding of ecological effects of TiO2 NPs.
authors.affiliation: College of Environmental and Biological Engineering, Putian University, Fujian, China; Department of Environmental Science, Zhejiang University, Hangzhou, China.
authors.forename: Xiuchun
authors.initials: X
authors.lastname: Lin
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou, China.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou, China.
authors.forename: Si
authors.initials: S
authors.lastname: Ma
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou, China.
authors.forename: Gesheng
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Yang
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Beijing, P. R. China.
authors.forename: Meiping
authors.initials: M
authors.lastname: Tong
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou, China.
authors.forename: Daohui
authors.initials: D
authors.lastname: Lin
mesh_terms: D004926:Escherichia coli / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity* / Q000648:ultrastructure; D050296:Microbial Viability; D009994:Osmolar Concentration; D018384:Oxidative Stress; D010316:Particle Size; D017382:Reactive Oxygen Species / Q000378:metabolism; D014025:Titanium / Q000737:chemistry
chemical_list: D017382:Reactive Oxygen Species; C009495:titanium dioxide; D008315:Malondialdehyde; D014025:Titanium