In the near future, doctors may be able to use tiny particles to speed up bone growth, re-attach torn ligaments and even sense and transmit information about bacterial infections.
Associate Professor of Engineering Thomas Webster has been working on applications like these and more for "nanoparticles" - materials that measure on the scale of just a few nanometers, or mere billionths of a meter. For perspective, "the diameter of an average human hair is 80,000 nanometers," Webster said.
Some of the most promising nano-research has been done in the field of orthopedics, but nanoparticles may soon be used to heal vasculature, cartilage, neurons and skin, as well as bone, Webster said.
"We hope to hit all the organs in the body," he said.
By changing the shape of materials at the nanoscale, researchers have been able to increase the rate of growth of various body systems after surgery. The interactions between microscopic features of different particles can affect the rate of recovery of the system by allowing cells like those in bone to get a better grip on whatever surface they are growing on. For example, if a patient receives a titanium hip implant, instead of letting the bone try to grow over the smooth titanium, only to slip off, doctors can coat the titanium in nanoparticles so the bone will stick to them like velcro.
Professor of Orthopedics Roy Aaron is collaborating with Webster in his nanoparticle research. The nanoparticles create a "better interface" between the body and the implant, leading to a more effective "bio-hybrid," Aaron said.
According to Webster, the nanoparticles are made from the same materials that occur naturally in the body, so they are able to "trick the body into thinking you are inserting itself." In addition, the particles do not cause scar tissue to form - what usually happens when someone has a hip replacement or other surgery. This lack of scar tissue likely contributes to the rapid re-growth.
Aaron said "a lot of research" has been done on the uses of nanoparticles in orthopedics. He sees many potential uses for nanoparticles in medicine, but he also has "a lot of concerns."
Some of those concerns stem from the fact that nanoparticles are so small - too small, perhaps. They are able to travel through cell membranes, and some studies have suggested that they may disrupt cell function and even cause cancer. Aaron said that the use of tiny particles warrants further research even if the particles are made out of a material that has been safe in larger quantities.
For example, he said, while a titanium hip does not bother the body, titanium powder created from the wear and tear of titanium implants triggers an inflammatory response. Similarly, nanoparticles may affect the body in unexpected ways. Webster says that so far in his research the particles have had no harmful effects on animal models, but both Webster and Aaron agree that human testing will not begin for another five to 10 years, after many further pre-clinical studies have been conducted.
In the field of orthopedics, nanoparticles will initially be used to increase the rate of bone growth. But the future may hold even more astounding developments. Webster's lab is currently working on using nanoparticles to release antibiotics when sensors determine that there is an infection. Nanoparticles could measure glucose levels and send that information to a device that could regulate the amount of glucose in the blood.
Even though the research is still in early stages, many have not been discouraged from seeking out Webster's help. Webster said he has received calls from hundreds of people interested in participating in clinical studies. To him, this fact emphasizes the great importance of this kind of research.
"People are in that much pain that they are willing to try exploratory techniques," he said.
