Toxicological assessment of TiO2 nanoparticles by recombinant Escherichia coli bacteria.
Rapid and efficient methods to assess nanoparticle toxicity are desired in current research. Here we showed that Escherichia coli labeled by green fluorescent protein can be a good model bacterium for assessing acute toxicity of TiO(2) (about 50% inhibition ratios after 135 min exposure). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that TiO(2) nanoparticles (NPs) can influence certain protein expression in the recombinant bacterium, and the obvious effects in repressed expression and elevated expression were observed in 30/40, 10/20 μg mL(-1) treated cells, respectively. However, the GFP expression (27 kD) was not influenced by introduced TiO(2) NPs. The change of the fluorescence intensity may be caused by the damage in folding and chromophore formation of the GFP post-translational modification due to generated reactive oxygen species. Furthermore, TiO(2) NPs at higher concentrations decreased their toxicity because of aggregation. 20 μg mL(-1) humic acid (HA) introduced to the medium can decrease the fluorescent inhibition owing to the barrier of steric hindrance it provides between NPs and cells.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, PR China.
Guoxiang
G
Jiang
Zhenyao
Z
Shen
Junfeng
J
Niu
Yueping
Y
Bao
Jing
J
Chen
Tiande
T
He
D003470:Culture Media; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010316:Particle Size; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry / Q000633:toxicity*; D018675:Toxicity Tests / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
D003470:Culture Media; D029968:Escherichia coli Proteins; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D014874:Water Pollutants, Chemical; D049452:Green Fluorescent Proteins; C009495:titanium dioxide; D014025:Titanium