The degree and kind of agglomeration affect carbon nanotube cytotoxicity

Our plain-English summary of The degree and kind of agglomeration affect carbon nanotube cytotoxicity, by P. Wick, P. Manser, L.K. Limbach, et al (Toxicology Letters, 2007).

The study

• Authors: P. Wick, P. Manser, L.K. Limbach, U. Dettlaff-Weglikowska, F. Krumeich, S. Roth, W.J. Stark, A. Bruinink
• Journal: Toxicology Letters
• Published: 2007;168(2):121-31
• Cited by: 431 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The urgent need for toxicological studies on carbon nanotubes (CNTs) has arisen from the rapidly emerging applications of CNTs well beyond material science and engineering. In order to provide a basis for comparison to existing epidemiological data, we have investigated CNTs at various degrees of agglomeration using an in vitro cytotoxicity study with human MSTO-211H cells. Non-cytotoxic polyoxyethylene sorbitan monooleate was found to well-disperse CNT. In the present study, the cytotoxic effects of well-dispersed CNT were compared with that of conventionally purified rope-like agglomerated CNTs and asbestos as a reference. While suspended CNT-bundles were less cytotoxic than asbestos, rope-like agglomerates induced more pronounced cytotoxic effects than asbestos fibres at the same concentrations. The study underlines the need for thorough materials characterization prior to toxicological studies and corroborates the role of agglomeration in the cytotoxic effect of nanomaterials.

In plain English

This laboratory study tested how single-walled carbon nanotubes affected human cells in culture, using crocidolite asbestos as a comparison. The authors used a human mesothelioma cell line, MSTO-211H, chosen to allow comparison with existing asbestos data. From one batch of nanotubes they prepared four forms: the raw material; an acid-purified form that clumped into rope-like agglomerates; well-dispersed bundles suspended with a food-additive surfactant; and a sediment made mainly of non-tube carbon. Cells were exposed to three concentrations of each material, or crocidolite, for 3 days. At the concentrations tested, the surfactant alone caused no visible or significant change in cell shape, activity or growth. Crocidolite caused a clear toxic response. The rope-like agglomerates were more toxic than the dispersed bundles and caused cell changes similar to those seen with asbestos. The dispersed bundles caused no visible changes in cell shape. The authors concluded that the dispersed bundles were less cytotoxic than asbestos and the agglomerates more so. They also concluded that the degree of dispersion and the carbon impurities, rather than the trapped nickel and yttrium, appeared to determine toxicity.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: in vitro (cell culture) cytotoxicity experiment
• Who was studied: Human mesothelioma cell line MSTO-211H, obtained from the American Type Culture Collection and grown in culture. Each experiment was repeated independently three times, with three replicate treatments per plate.
• Exposure: Single-walled carbon nanotube material bought from Yangtze Nanotechnology, Shanghai, China, prepared in four forms: raw material, acid/oxidation-purified rope-like agglomerates, bundles dispersed with the surfactant polyoxyethylene sorbitan monooleate (PS80), and a pellet of mainly non-tube carbon. Crocidolite asbestos from the National Research Institute for Occupational Diseases (Johannesburg, South Africa) served as the reference. The text prints the three concentrations as 7.5, 15 and 30 g per milliliter (a 'micro' prefix appears to have been lost). Exposure lasted 3 days.
• Main results:
  • Within the range tested, the surfactant PS80 caused no significant changes in the measured endpoints: cell shape, cell activity and cell proliferation.
  • Crocidolite asbestos caused a clear cytotoxic response in the MSTO-211H cells.
  • The dispersed nanotube bundles were less toxic than the rope-like nanotube agglomerates.
  • Cells exposed to the dispersed bundles showed no visible changes in shape compared with control cells.
  • Cell shape changes and loss of cell performance after asbestos treatment were similar to those after treatment with the nanotube agglomerates.
  • The authors reported that all nanotube fractions significantly decreased cell activity and proliferation in a dose-dependent way.
• The authors' conclusion: The authors concluded that suspended nanotube bundles were less cytotoxic than asbestos, while rope-like agglomerates caused more pronounced cytotoxic effects than asbestos at the same concentrations. They also concluded that the presence of carbonaceous material and the degree of dispersion, not the entrapped yttrium and nickel, seemed to determine nanotube toxicity.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Crocidolite.

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