Journal
AQUATIC TOXICOLOGY
Volume 100, Issue 2, Pages 194-201Publisher
ELSEVIER
DOI: 10.1016/j.aquatox.2010.07.001
Keywords
Multiwalled carbon nanotubes; Ecotoxicity; Marine algae; Photosystem II; Glutathione; Seawater; Nanoparticles; Aggregates
Categories
Funding
- National Science Foundation
Ask authors/readers for more resources
The multiwalled carbon nanotubes (MWNTs) are novel materials with many potential applications. The ecotoxicity of these materials is not well studied, but it is essential for environmental impact assessments. In this study a commercially available MWNT material was carboxylated by microwave assisted acid oxidation. This functionalized MWNT (f-MWNT) material was examined for toxicity effects using unicellular marine green alga Dunaliella tertiolecta. D. tertiolecta was exposed to f-MWNT which had been pre-equilibrated with culture media for 24 h. Substantial growth lag phase was observed at 5 and 10 mg L-1 f-MWNT, and the resulting 50% effective concentration (EC50) on 96-h growth was 0.82 +/- 0.08 mg L-1. During mid-exponential growth phase cytotoxicity was evidenced at 10 mg L-1 f-MWNT in 36% reduction in exponential growth rate, 88 mV more positive glutathione redox potential (indicative of oxidative stress), 5% and 22% reduction in photosystem II (PSII) quantum yield and functional cross section respectively, all relative to the control cultures. However, when the large f-MWNT aggregates in the media with 10 mg L-1 f-MWNT were removed by 0.2 mu m filtration. D. tertiolecta did not show significant cytotoxicity effects in any of the above parameters. This suggests that the cytotoxicity effects originated predominately from the large f-MWNT aggregates. Analysis of the f-MWNT aggregation dynamics suggests active interaction between f-MWNT and algal cells or cell metabolites that promoted f-MWNT aggregation formation. The f-MWNT particles were also found absorbed on algal cell surface. The direct contact between f-MWNT and cell surface was likely responsible for reduced PSII functional cross section and oxidative stress during exponential growth. Published by Elsevier B.V.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available