Carbon nanotubes (CNTs) are taken up into the body dependent on the administration route and their composition (single-walled, multi-walled, modified) and can later be found in different organs and cell types. However, it is not possible to make a general statement on the behaviour of carbon nanotubes once within the body due to numerous differences of used CNTs, various applications and analytical methods.


Carbon nanotubes show a typical "fibre-like" behaviour with the length of the individual CNT fibres playing a decisive role for the severity of their biological effects. Based on currents studies, the uptake of CNTs across the lung is the most critical entry pathway for carbon nanotubes into the body, because fibres have a longer residence time in the lung compared to spherical materials. Therefore, the aspect ratio of diameter to length is the determining factor for CNT-fibres [1].


Carbon nanotubes of a certain length, like other fibre-shaped harmful materials, cannot be removed from the lung by regular cleaning processes. The fibres keep being stuck in the lung tissue causing a permanent irritation of the tissue. This may even go so far that the fibres migrate into deep tissue layers causing an inflammation for years or decades, which ultimately may trigger tumour development [2]. This is in perfect agreement with a recent study in rats which demonstrated exactly this relationship between the length of the carbon nanotubes and their effect on the formation of granuloma within the treated animals [3].


These effects also explain the comparison with asbestos fibres, although this is only applicable to very long fibres (>5-10 µm). Short carbon nanotubes do not show this effect and can therefore be used in technical applications [4].



Literature arrow down

  1. Donaldson, K et al. (2011), Nanomedicine (Lond), 6(1): 143-156.
  2. Marquardt H., Schäfer S. & Barth H. (2013). Toxikologie, Toxikologie - 3., vollst. überarb. erw. Aufl. 2013., Kapitel 34: Fasern und Nanopartikel, S. 885ff. Wissenschaftliche Verlagsgesellschaft Stuttgart, ISBN 978-3-8047-2876-9.
  3. Rittinghausen, S et al. (2014), Part Fibre Toxicol, 11(1): 59.
  4. Donaldson, K et al. (2013), Adv.Drug Deliv.Rev., 65(15): 2078-2086.



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