Carboxyl-modified polystyrene nanoparticles (COO-PS-NPs) have many potential applications, for example drug-delivery systems, but their toxicity remains poorly assessed. In the current study, characterisation, uptake and toxicity of two sized COO-PS-NPs in cultured BEAS-2B lung epithelial cells were investigated. The 20nm sized COO-PS-NPs tended to aggregate heavily in the cell culture media yielding larger aggregates, in contrast the 100nm COO-PS-NPs were stable. Electron and confocal microscopy demonstrated that COO-PS-NPs rapidly accumulate in vesicle-like structures within cells and fluorescent organelle co-staining showed the presence of 20nm COO-PS-NPs in mitochondria and the 100nm COO-PS-NPs in Golgi apparatus. Cellular studies revealed that COO-PS-NPs cause GSH depletion and induce ROS generation resulting in oxidative stress. Studies in a cell-free system showed that COO-PS-NPs directly deplete levels of GSH in solution. Size- and concentration-dependent DNA strand breaks (by comet assay) were also observed and both 20nm and 100nm COO-PS-NPs induced caspases-3/7 activation in a Ca2+ independent manner, however a significant decrease in cell viability was observed only at high concentrations of 20nm COO-PS-NPs. In summary, this in vitro study demonstrated that toxicity of the 20nm COO-PS-NPs is mediated by oxidative stress after co-localisation to the mitochondria and that further studies are needed to assess the safety of COO-PS-NPs.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:665765 |
| Date | January 2015 |
| Creators | Shuwaikan, Mohammed Salem |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/6155/ |
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