The present study evaluated phototoxicity of nanoparticulate ZnO and bulk-ZnO under natural sunlight (NSL) versus ambient artificial laboratory light (AALL) illumination to a free-living nematode Caenorhabditis elegans. Phototoxicity of nano-ZnO and bulk-ZnO was largely dependent on illumination method as 2-h exposure under NSL caused significantly greater mortality in C. elegans than under AALL. This phototoxicity was closely related to photocatalytic reactive oxygen species (ROS) generation by the ZnO particles as indicated by concomitant methylene blue photodegradation. Both materials caused mortality in C. elegans under AALL during 24-h exposure although neither degraded methylene blue, suggesting mechanisms of toxicity other than photocatalytic ROS generation were involved. Particle dissolution of ZnO did not appear to play an important role in the toxicity observed in this study. Nano-ZnO showed greater phototoxicity than bulk-ZnO despite their similar size of aggregates, suggesting primary particle size is more important than aggregate size in determining phototoxicity.
|Number of pages
|Published - Jun 2011
Bibliographical noteFunding Information:
This work was supported by the United States Environmental Protection Agency through Science to Achieve Results Grant number 832530 . The authors acknowledge Dr. Stephen Diamond for his constructive suggestions for improving the manuscript. The authors also acknowledge the Department of Physiology and Pharmacology at The University of Georgia for use of the Bio-Tek Synergy 4 microplate reader.
- Bulk ZnO
- Caenorhabditis elegans
- Nanoparticulate ZnO
- Reactive oxygen species (ROS)
ASJC Scopus subject areas
- Health, Toxicology and Mutagenesis