Effect of aqueous media on the copper-ion-mediated phototoxicity of CuO nanoparticles toward green fluorescent protein-expressing Escherichia coli.
Quantitative comparison of different aqueous media on the phototoxicity of copper oxide nanoparticles (CuO NPs) is crucial for understanding their ecological effects. In this study, the phototoxicity of CuO NPs toward the green fluorescent protein-expressing Escherichia coli (GFP-E. coli) under UV irradiation (365 nm) was investigated in Luria-Bertani medium (LB), NaCl solution, deionized water (DI) and phosphate-buffered saline (PBS). The phototoxicity of CuO NPs toward GFP-E. coli decreased in the order of DI>NaCl>PBS>LB because of different released concentrations of Cu(2+). The 3h released Cu(2+) concentrations by 10mg/L CuO NPs in DI water, NaCl solution, LB medium, and PBS were 1946.3 ± 75.6, 1242.5 ± 47.6, 1023.4 ± 41.2, and 1162.1 ± 41.9 μg/L, respectively. Transmission electron microscope and laser scanning confocal microscope images of E. coli exposed to CuO NPs demonstrated that the released Cu(2+) resulted in fragmentation of bacterial cell walls, leakage of intracellular components, and finally death of bacteria in four media after UV light irradiation. In each medium, the bacterial mortality rate logarithmically increased with the releasing concentrations of Cu(2+) by CuO NPs (R(2)>0.90) exposed to 3h UV light. This study highlights the importance of taking into consideration of water chemistry when the phototoxicity of CuO NPs is assessed in nanotoxicity research.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China.
Enxiang
E
Shang
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China.
Yang
Y
Li
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China. Electronic address: junfengn@bnu.edu.cn.
Junfeng
J
Niu
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China.
Huiyuan
H
Guo
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China.
Yijing
Y
Zhou
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China.
Han
H
Liu
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China.
Xinqi
X
Zhang
D002021:Buffers; D003300:Copper / Q000528:radiation effects / Q000633:toxicity*; D003470:Culture Media / Q000737:chemistry*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000235:genetics*; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D010782:Photolysis; D012965:Sodium Chloride / Q000737:chemistry; D012996:Solutions; D013499:Surface Properties; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry
D002021:Buffers; D003470:Culture Media; D012996:Solutions; D014867:Water; D049452:Green Fluorescent Proteins; D012965:Sodium Chloride; D003300:Copper; C030973:cupric oxide
CuO nanoparticles; Escherichia coli; Green fluorescent protein; Ion release; Phototoxicity; UV light