team led by U-M chemical engineering professor Walter
J. Weber Jr. tagged multi-walled carbon nanotubes—one
of the most promising nanomaterials developed to
date—with the carbon-14 radioactive isotope, which
enabled the nanotubes to be tracked and quantified
as they were absorbed into living cells. Researchers
used cancer cells called HeLa cells, and also measured
nanotube uptake in an earthworm and an aquatic type
The findings were presented Sunday at the 231st
American Chemical Society National Meeting in Atlanta.
Co-authors of the presentation are graduate student
Elijah Petersen and postdoctoral research assistant
Carbon nanotubes were discovered in 1991, and hold
great promise in several areas, including pharmacology
and for hydrogen storage in fuel cells, Weber said.
But despite their promise, a big problem is that
it's not known how multi-walled carbon nanotubes
will impact the living environment, Weber said.
"While everyone is concerned about this issue, there
has been no really adequate way before this development
to examine the extent to which they may get into
human cells, and what will result if they do," Weber
said. "Nobody has been able to do quantitative research
on this because no method to measure them has existed
until now. We were able to detect them, but had no
way to determine how much was there."
In tagging the nanotubes with the isotope, researchers
found that about 74 percent of the nanotubes added
to a culture of cancer cells were assimilated by
the cells after 15 minutes, and 89 percent of nanotubes
assimilated after six hours, according to the paper.
And the uptake was nearly irreversible, with only
about 0.5 percent of the nanotubes releases from
the cell after 12 hours.
It's important to understand if and how the multi-walled
carbon nanotubes accumulate in living cells, because
before the materials can become widely used in society
scientists must understand if they'll pass through
the food webs and possibly threaten the health of
ecosystems and lead to uptake by humans, Petersen
"This approach has virtually limitless potential
for facilitating important future investigations
of the behaviors of carbon nanotubes in environmental
and biomedical applications," Petersen said.
information on Prof. Weber .
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