| Bone-forming cells grow faster and produce more | | | | “What we found is possibly a terrific new |
| calcium on anodized titanium covered in carbon | | | | material for joint replacement and other |
| nanotubes compared with plain anodized titanium and | | | | implants,” said Webster, associate professor of |
| the non-anodized version currently used in | | | | engineering at Brown. “Right now, bone |
| orthopaedic implants, new Brown University research | | | | doesn’t always properly meld to implants. |
| shows. The work, published in Nanotechnology, | | | | Osteoblasts don’t grow or grow fast enough. |
| uncovers a new material that can be used to make | | | | Adding carbon nanotubes to anodized titanium |
| more successful implants. The research also shows | | | | appears to encourage that cell growth and |
| tantalizing promise for an all-new device: a | | | | function.” |
| “smart” implant that can sense and report on | | | | Webster’s long-term vision for the new material |
| bone growth. | | | | is ambitious. With it, Webster hopes to create a new |
| PROVIDENCE, R.I. [Brown University] — For | | | | class of implants – ones that can sense bone |
| orthopaedic implants to be successful, bone must | | | | growth then send that information to an external |
| meld to the metal that these artificial hips, knees and | | | | device. Doctors could monitor the output and |
| shoulders are made of. A team of Brown University | | | | determine whether to inject growth hormones or |
| engineers, led by Thomas Webster, has discovered a | | | | otherwise intervene to avoid additional surgery. Right |
| new material that could significantly increase this | | | | now, implant patients must get an X-ray or undergo |
| success rate. | | | | a bone scan to monitor bone growth. |
| Nanotubes | | | | Webster thinks these “biosensing” implants |
| “Possibly a terrific new material” | | | | could even be designed to detect infection and be |
| A titanium surface covereed by carbon nanotubes | | | | specially coated to release antibiotics or other drugs |
| could lead to faster, better growth of implanted | | | | into the body. |
| bone-growing cells and an improved success rate for | | | | Webster said the biosensing concept would work |
| orthopaedic surgery. The carbon nanotubes could | | | | because when cells make calcium, an electrical current |
| could even self-report, keeping doctors informed | | | | is created. That current can be conducted through |
| about the healing process. | | | | carbon nanotubes and transmitted via radio |
| Image: Sirinrath Sirivisoot/Brown University | | | | frequency to a handheld device outside the body |
| The secret: carbon nanotubes on anodized titanium. | | | | – a similar process to the one employed by |
| The team took titanium – the most popular | | | | state-of-the-art cardiac pacemakers. |
| implant material around – and chemically treated it | | | | “This technology would be incredibly |
| and applied an electrical current to it. This process, | | | | exciting,” Webster said. “It could significantly |
| called anodization, creates a pitted coating in the | | | | improve patient health – and cut down on |
| surface of the titanium. Webster and his team | | | | expensive diagnostic tests and surgery. We still have |
| packed those pits with a cobalt catalyst and then ran | | | | a long way to go to make an intelligent implant a |
| the samples through a chemical process that involved | | | | reality, but our new results are a strong first |
| heating them to a scorching 700° C. That caused | | | | step.” |
| carbon nanotubes to sprout from each pit. | | | | Webster’s Brown research team included |
| Researchers then placed human osteoblasts, or | | | | engineering graduate student Sirinrath Sirivisoot, the |
| bone-forming cells, onto the nanotube-covered | | | | lead author of the Nanotechnology article, engineering |
| samples as well as onto samples of plain and | | | | graduate students Chang Yao and Xingcheng Xiao |
| anodized titanium. The samples were placed in an | | | | and professor of engineering Brian Sheldon. |
| incubator. After three weeks, the team found that | | | | The Coulter Foundation funded the research. |
| the bone cells grew twice as fast on the titanium | | | | Editors: Brown University has a fiber link television |
| covered in nanotubes. Cells interacting with the | | | | studio available for domestic and international live and |
| nanotubes also made significantly more calcium – | | | | taped interviews and maintains an ISDN line for radio |
| the essential ingredient for healthy bones. | | | | interviews. |
| Results are published in Nanotechnology. | | | | |