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Imbalance between oxidative and antioxidative systems: Toward an understanding of visible light-induced titanium dioxide nanoparticles toxicity.
MedLine Citation:
PMID:  24080005     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The broad application of titanium dioxide nanoparticles (TiO2 NPs) has resulted in the release of substantial quantities of untreated TiO2 NPs into aquatic systems, which serve as the terminal sink for nanomaterials. These TiO2 NPs may induce some unexpected toxic effects to aquatic systems. The objectives of this research were to evaluate toxic effects of low dosage TiO2 NPs on Tetrahymena pyriformis under visible-light illumination conditions and further discuss possible mechanisms. The results showed that TiO2 NPs accumulated as aggregates in cytosolic vesicles of T. pyriformis. Cell numbers and viability of TiO2 NPs-exposed groups decreased to (20.2±1.8)% and (17.3±1.9)% after 24h continuous 12000 Lx illumination. Compared with the dark control, the intracellular reactive oxygen species (ROS) levels increased (1.9-fold) by the combination of 5mgL(-1) TiO2 NPs and 12000 Lx illumination. Even incubation in the dark for 6h after 12h illumination, superoxide dismutase (SOD) activity of TiO2 NPs exposed groups still maintained at the high level (about 3.9-fold of dark control). Meanwhile, illumination-induced TiO2 NPs led to a reduction of scavenging hydroxyl radicals (OH) activity with an average of (14.3±6.5)%. Under illumination conditions, overproduction of reactive oxygen species (ROS) by TiO2 NPs exceeded the scavenging capability of T. pyriformis and then led to the breakdown of oxidative/anti-oxidative systems, further resulting in cell growth delay and mitochondria dysfunction. All the results revealed that via visible light excitation, oxidative injury may be responsible for the toxic effects of TiO2 NPs on T. pyriformis.
Authors:
Xiao-Yan Zou; Bin Xu; Chang-Ping Yu; Hong-Wu Zhang
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-9-27
Journal Detail:
Title:  Chemosphere     Volume:  -     ISSN:  1879-1298     ISO Abbreviation:  Chemosphere     Publication Date:  2013 Sep 
Date Detail:
Created Date:  2013-10-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0320657     Medline TA:  Chemosphere     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2013 Elsevier Ltd. All rights reserved.
Affiliation:
Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China.
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