Carbon nanotube cluster viewed through an electron microscope.
Carbon nanotube cluster viewed through an electron microscope.

In a new study, published today in the journal Angewandte Chemie, long, pristine nanotubes can be made shorter as a result of chemical treatment.

Carbon nanotubes are sheets of carbon atoms rolled up into hollow tubes just a few nanometres in diameter. Engineered carbon nanotubes can be chemically modified, with the addition of chemotherapeutic drugs, fluorescent tags or nucleic acids.

In 2008, concerns were highlighted about the carcinogenic risk from the exposure and persistence of carbon nanotubes in the human body. Some studies indicate that when long untreated carbon nanotubes are injected to the abdominal cavity of mice they can induce unwanted responses resembling those associated with exposure to certain asbestos fibres.

In this recent paper, the authors concluded that not all chemical treatments alleviate the toxicity risks associated with the material; only reactions that are able to render carbon nanotubes short and stably suspended in biological fluids without aggregation are able to result in safe, risk-free material.

“The apparent structural similarity between carbon nanotubes and asbestos fibres has generated serious concerns about their safety profile and has resulted in many unreasonable proposals of a halt in the use of these materials even in well-controlled and strictly regulated applications, such as biomedical ones," said Professor Kostas Kostarelos, Chair of Nanomedicine at the UCL School of Pharmacy. "What we show for the first time is that in order to design risk-free carbon nanotubes, both chemical treatment and shortening are needed."

Kostarelos led the research with Doctor Alberto Bianco of the CNRS in Strasbourg, France, and Professor Maurizio Prato of the University of Trieste, Italy.