Electron microscope image of a multi-walled carbon nanotube coated with aluminum oxide by atomic layer deposition.A new interdisciplinary study has shown that coating multi-walled carbon nanotubes (CNTs) with aluminum oxide could lower the risk of lung injuries such as pulmonary fibrosis. Based on laboratory experiments on mice, researchers from North Carolina State University and the National Institute of Environmental Health Sciences (NIEHS) in the US found that the coating helped to reduce the health risk from CNTs, which are being increasingly produced and used for a range of possible applications in areas such as electronics, structural engineering and medicine.
The work, which featured in the open access, peer-reviewed journal PLOS ONE [Taylor, et al. PLOS ONE (2014) DOI: 10.1371/journal.pone.0106870], is part of collaborative research into predicting and preventing potential human health risks linked with emerging nanotechnologies, and to achieve a better understanding of the human health effects of carbon nanotubes. As senior author of the work, James Bonner, pointed out: “Our goal is to find ways to make sure that carbon nanotubes don’t become the next asbestos.”
“Our goal is to find ways to make sure that carbon nanotubes don’t become the next asbestos.”James Bonner
Although CNTs are one of the most commonly engineered nanomaterials, previous studies have shown pristine or unmodified carbon nanotubes can cause pulmonary fibrosis/lung scarring and lung inflammation in animals and cellular models after inhalation exposure in a similar way as asbestos. The team used atomic layer deposition to coat the CNTs with a thin film of aluminum oxide, before exposing the mice to a single dose through inhalation. Although the coating wasn’t able to eliminate the health risks from multi-walled CNTs, it was shown to reduce problems such as pulmonary fibrosis.
They were investigating if nanotubes modified by atomic layer deposition coatings would have an effect on the severity of such fibrosis, especially as such modification is currently the most common way to enhance the functional properties of carbon nanotubes used in products such as those based on microelectronics that require an accurate thickness and uniform surface, as well as biomedical applications involving surface properties that are crucial for directing the interactions of the material with cells or tissues to help ensure they are more biocompatible.
The scientists are now looking to assess the toxicity of different types of multi-walled CNTs engineered by atomic layer deposition with other metal oxides to check if they are safer that uncoated nanotubes, and are also interested to know if modified nanotubes could result in other health problems, such as autoimmune disease or adverse effects on different organs.