Findings by a team of researchers from Oak Ridge National
Laboratory and the University of Tennessee bode well for using
single-walled carbon nanohorns, a particular form of engineered
carbon-based nanoparticles, for drug delivery and other commercial
applications.
In results to be published in the journal Nanotoxicology (http://www.nanotoxicology.net),
a team led by Meng-Dawn Cheng of ORNL’s Environmental
Sciences Division reported no pulmonary toxicity issues for
single-walled carbon nanohorns. These findings are contrary to numerous
studies in rats involving single-walled carbon nanotubes that have
different shapes and sizes than those of nanohorns.
“We think the difference could be due to the lack of
metal contaminants in single-walled carbon nanohorns as compared to
single-walled carbon nanotubes, although many factors could be the
cause as well,” said one of the co-authors, Brynn Voy of
ORNL’s Biosciences Division.
Nanohorns are short, horn-shaped tubular structures capped
with a conical tip. Individual nanohorns tend to cluster and form a
Dahlia, or star-like, structure between 50 nanometers and 100
nanometers in diameter with the tips of individual nanohorns projecting
outward from the center in all directions.
Of particular relevance is the fact nanohorns can be produced
through simple laser ablation of a pure carbon target without the use
of transition metal catalysts. Researchers theorize that the metal
contaminants might be the cause of inflammatory responses and oxidative
stress reported in inhalation studies using single-walled carbon
nanotubes.
“Our primary objective in this study was to
characterize the pulmonary response of single-wall carbon nanohorns and
compare our results to published data concerning single-wall carbon
nanotubes,” the authors wrote. They acknowledge that the two
forms of nanostructures can be vastly different in eliciting biological
responses so they took great care in making the comparison.
In addition to nanohorns’ potential for drug
delivery purposes, researchers believe they can be useful for hydrogen
storage in energy and fuel cell applications. Authors of the paper
believe carbon nanohorns could find large-scale applications sooner
than carbon nanotubes because they are easier to produce and because of
the likelihood that they do not pose a health hazard.
Posted 20th August 2007
