Body handles nanofiber better
Kimberly Patch and Eric Smalley,
Technology Research News
Living tissue often reacts to foreign objects
by encapsulating them in scar tissue. This is a problem with orthopedic
implants like artificial hips and neural implants like electrical probes.
Researchers from Purdue University have made a discovery that
may help: carbon nanofibers are surprisingly compatible with human tissue.
Their experiments showed that increasing the amount of carbon
nanofibers in a polycarbonate urethane composite implant increased the
functions of nerve and bone-forming cells and decreased the function of
scar-tissue formation. "My lab has shown increased in vitro tissue regeneration
for a number of tissues including bone, cartilage, vascular and bladder,"
said Thomas J. Webster, an assistant professor of biomedical engineering
at Purdue University.
The material could eventually be used to create better bone and
neural implants, said Webster.
Carbon nanofibers are woven from carbon nanotubes, which are rolled-up
sheets of carbon atoms that are a natural ingredient of soot. Nanotubes
have useful electrical properties, are very strong, and are very small.
They can be narrower than one nanometer, which is the width of ten hydrogen
The results imply that compatibility has to do with the size of
the fibers that make up the materials. "We believe nano phase materials
hold much promise in tissue regeneration since tissues in our bodies are
nanostructured" themselves, said Webster. "Cells in our bodies are accustomed
to interacting with surfaces with many nano features," he said. "Nano
materials can duplicate such architectures."
The researchers have also shown that other materials that contain
surfaces with nano-size features are also more compatible with the human
body. "A wide range of materials that contain nano features, including
metals, ceramics, polymers and composites," has shown increased in vitro
tissue regeneration, according to Webster. "We believe this opens a wide
new door for all nano materials in tissue engineering applications," he
Potential practical applications include coatings for orthopedic
implants like hip and ankle replacements. "Materials are badly needed
which can obtain a firm attachment with bone tissue," said Webster. "The
current average lifetime of... orthopedic implants is only 15 years,"
he said. "Carbon nanofibers/nanotubes may be one of those materials."
Carbon nanofibers are especially appropriate as a material to
make up electrodes that could monitor or repair electrical activity in
the brain. Currently silicon electrodes are used for this purpose, but
they tend to induce scar tissue, which keeps the electrodes from making
contact with neurons. "This study suggests that such scar tissue can be
decreased by using small nano-dimension carbon nanofibers," said Webster.
Carbon nanotubes also have strong electrical properties. "These
carbon nanofibers also interact with neurons, which means if used as electrodes
they can establish electrical connection with the brain," Webster said.
Carbon nanofiber materials could be used in orthopedics in five
to ten years, but it will be one to two decades before neural applications
are practical, said Webster.
The next step in exploring the use of the material for establishing
electrical connection with neural tissue is animal studies, said Webster.
"A lot needs to be done to achieve these final results," said Webster.
"The in vitro environment is quite different from the in vivo environment,"
Webster's research colleagues were Michael C. Waid, Janice L.
McKenzie, Rachel L. Price and Jeremiah U. Ejiofor. The work appeared in
the January, 2004 issue of Nanotechnology. The research was funded
by the National Science Foundation (NSF) and the Purdue Research Foundation.
Timeline: 5-10 years, 10-20 years
Funding: Government; University
TRN Categories: Nanotechnology; Biotechnology; Materials
Science and Engineering
Story Type: News
Related Elements: Technical paper, "Nano-Biotechnology:
Carbon Nano Fibers As Improved Neural and Orthopedic Implants" Nanotechnology,
December 17/24, 2003
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