RIVERSIDE, Calif. www.ucr.edu — Osteoporosis sufferers and victims of broken bones may have the tiniest of friends in carbon nanotubes, according to researchers at the University of California, Riverside.
The strength, flexibility and light weight of carbon nanotubes — structures 100,000 times smaller than a human hair — allow them to act as scaffolds to hold up regenerating bone, according to Distinguished Professor of Chemistry Robert C. Haddon, the director of the Center for Nanoscale Science and Engineering at UC Riverside.
“They’re the perfect replacement: Small, strong, and they’re carbon based,” said Haddon, lead author of a paper titled A Bone Mimic Based on the Self-Assembly of Hydroxyapatite on Chemically Functionalized Single-Walled Carbon Nanotubes, which was published in June in the American Chemical Society’s journal Chemistry of Materials. Haddon’s UCR co-authors included graduate students Bin Zhao and Hui Hu, and postdoctoral researcher Swandhin K. Mandal.
The findings by Haddon and his colleagues may lead to improved flexibility and strength of artificial bone, new types of bone grafts and to inroads in the treatment of osteoporosis. Haddon expects it will attract interest from other researchers and companies interested in developing new bone-graft materials and techniques.
Artificial bone scaffolds have been made from a wide variety of materials, such as polymers or peptide fibers. Their drawbacks include low strength and the potential for rejection in the body.
Single-walled carbon nanotubes are a form of carbon, like graphite or diamond, where the atoms are arranged like a rolled-up tube of chicken wire. They are among the strongest known materials in the world.
Bone tissue is a natural composite of collagen fibers and crystalline hydroxyapatite, which is a mineral based on calcium phosphate. Haddon and his team have demonstrated that carbon nanotubes can mimic the role of collagen as a scaffold for inducing the growth of hydroxyapatite crystals.
The trick, Haddon said, was finding a way to cluster the growth of hydroxyapatite crystals on the carbon nanotube scaffold. By chemically treating the nanotubes, it was possible to attract calcium ions and this promoted the crystallization process while improving the biocompatibility of the nanotubes by increasing their water solubility.
Haddon’s findings also show that nanotechnology can be used in a variety of ways to help the body heal itself.
He and Assistant Professor of Neuroscience, Vladimir Parpura, together with other UCR researchers are investigating the role of carbon nanotubes in the formation of similar scaffolds to stimulate the growth of neurons.
