Safety fears about carbon nanotubes, due to their
structural similarity to asbestos, could have been
alleviated following a new research showing how to
remove their toxic properties.
In a new study, published today in the journal
Angewandte Chemie, evidence is provided that the
asbestos-like reactivity and pathogenicity reported
for long, pristine nanotubes can be completely
alleviated if their surface is modified and their
effective length is reduced as a result of chemical
treatment.
First atomically described in the 1990s, 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 – opening
up applications in cancer and gene therapy.
Furthermore, these chemically modified carbon
nanotubes can pierce the cell membrane, acting as a
kind of ‘nano-needle’, allowing the possibility of
efficient transport of therapeutic and diagnostic
agents directly into the cytoplasm of cells.
Among their downsides however, have been concerns
about their safety profile. One of the most serious
concerns, highlighted in 2008, involves the
carcinogenic risk from the exposure and persistence
of such fibres in the 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 paper, the authors describe two different
reactions which ask if any chemical modification can
render the nanotubes non-toxic. They conclude that
not all chemical treatments alleviate the toxicity
risks associated with the material. Only those
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.
Professor Kostas Kostarelos, Chair of Nanomedicine
at the UCL School of Pharmacy who led the research
with his long term collaborators Doctor Alberto
Bianco of the CNRS in Strasbourg, France and
Professor Maurizio Prato of the University of
Trieste, Italy, said: “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. What we show
for the first time is that in order to design
risk-free carbon nanotubes both chemical treatment
and shortening are needed.”
He added: “Creative strategies to identify the
characteristics that nanoparticles should possess in
order to be rendered ‘safe-for-use’, and the ways to
achieve that, are essential as nanotechnology and
its tools are maturing into applications and
becoming part of our everyday lives.”
More informations
http://www.ucl.ac.uk/pharmacy
(MDN)
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