Shorter fibers key to safer carbon nanotubes.
Ali-Boucetta, H, A Nunes, R Sainz, MA Herrero, B Tian, M Prato, A Bianco and K Kostarelos, 2013. Asbestos-like pathogenicity of long carbon nanotubes alleviated by chemical functionalization, Angewandte Chemie International Edition http://dx.doi.org/10.1002/anie.201207664.
A shorter carbon nanotube may be a safer one, according to a group of European researchers who varied the materials' structural fibers and tested their health effects in mice.
Carbon nanotubes are one of the most common and exciting examples of nanotechnology with potential uses in electronics and medicine, but they are made of fibers that resemble asbestos. The modified nanotubes with shorter fibers were less irritating to the mouse lung and showed no signs of cancer when compared to traditional carbon nanotubes.
This work demonstrates the importance of researchers from different disciplines teaming up to solve problems. When applied to green chemistry, toxicologists and chemists working together can create safer materials to help avoid unintended health and environmental consequences of new chemicals.
Many scientists predict that carbon nanotubes will have many useful applications. The nanomaterials could boost performance of our electronic devices, deliver drugs directly to cells and even enable more affordable space travel through lighter materials.
At the same time, other scientists and health experts worry that carbon nanotubes could create health problems in people. In particular, the fibrous structure of these tubes closely resembles the potent carcinogen asbestos. In fact, lab and animal studies have shown that carbon nanotubes do irritate lung tissue in the same way and lead to lung cancer in exposed animals.
Asbestos has been used in building materials, auto parts and coatings as an insulator and fire retardant. Asbestos fibers are released when products containing asbestos age or are disturbed in remodeling or replacement. When breathed in, the fibers can irritate lung tissue, causing cancer and other lung disease.
Now, a group of scientists report that they can make carbon nanotubes – picture sheets of carbon rolled into a cylinder – that are much safer and have fewer asbestos-like health effects.
By chemically modifying the surface of the very small carbon nanotubes, the researchers created fibers that are 10 times shorter than typical nanotube fibers. They tested these new materials head-to-head in mice with both untreated nanotubes and asbestos fibers.
They found that the chemical treatment produces fibers that caused much less irritation in the mouse lungs and did not show signs of cancer development during the seven days after injecting the nanotubes into the lungs.
More work and further testing are needed to understand the long-term impact of the modified nanotubes, including more details about biological interactions with the new nanomaterials.
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