An Overview of Human Nanotoxicology and Investigations of Aquatic Nanotoxicology in Fullerene (nC60) and Single Wall Carbon Nanotube (SWCNT) Exposed Invertebrates and Fish

Speaker(s): 
Date: 
August 17, 2005 - 12:00pm
Location: 
Bldg. 90

The presentation will provide basic background of the toxicology of manufactured nanoparticles in humans and present several studies in various aquatic organisms. Fullerene is engineered to be redox active and it is thought that the potential toxicity of fullerene exposure is related to the formation of reactive oxygen species. Acute toxicity and reproductive studies in Daphnia magna have shown that the method of fullerene solubilization has a large impact on toxicity and that fullerene exposure reduces brood size over time. Nano-iron used in remediation is ingested by daphnia and can coat their carapace, including filtering apparatus and appendages, but has low acute toxicity.  -- Another invertebrate, Hyalella azteca, is relatively resistant to fullerene and several studies of fullerene exposure in water, with and without the presence of humic acids, and via food ingestion were without significant effect.  --  Water-soluble fullerene (nC60) induces lipid peroxidation (LPO) in the brains of juvenile largemouth bass (Micropterus salmoides) and up-regulates genes related to an inflammatory response and genes related to metabolism of organic molecules, most notably CYP2K4. .  -- In another fish study, the exposure regime was expanded to include peptide-coated and uncoated single-walled carbon nanotubes (SWCNT) and in vitro metabolism. Adult male fathead minnows (Pimephales promelas) in 1L aquaria were dosed for 48 hrs with either a) 0.5 ppm nC60; b) 0.2 ppm Nano-1 wrapped SWCNT; or c) 0.2 ppm SWCNT, with a 50% water change at 24 hrs. Both coated SWCNT and uncoated SWCNT were detected in fecal material collected from the digestive tract, as verified by Raman spectroscopy. Clumps of coated but not uncoated SWCNT were visible on the gill. However, uncoated SWCNT caused increased gill LPO while the coated SWCNT was protective for this endpoint. Protein expression assays indicated that nC60 elevated LPO in the brain and both nC60 and SWCNT significantly increased LPO in gill and expression of CYP2 family isozymes in liver. BSA-coated SWCNT interfered with biotransformation enzyme  (7-ethoxycoumarin) activity in an in vitro liver microsome assay.

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