Smart Coating Promotes Bone Growth For Implants
The coating, developed by researchers at North Carolina State University, fosters bone growth into an implant as it creates a crystalline layer next to the implant, and a mostly amorphous outer layer that touches the surrounding bone.
The amorphous layer dissolves over time, releasing calcium and phosphate, which encourages bone growth.
“The bone grows into the coating as the amorphous layer dissolves, resulting in improved bonding, or osseointegration,” says Dr. Afsaneh Rabiei, an NC State associate professor of mechanical and aerospace engineering, associate faculty member of biomedical engineering and co-author of a paper describing the research.
This bonding also makes the implant more functional, because the bonding helps ensure that the bone and the implant do a better job of sharing the load.
“We call it a smart coating because we can tailor the rate at which the amorphous layer dissolves to match the bone growth rate of each patient,” Rabiei says. This feature of the technology helps address the variation in rates of bone growth among populations.
Silver nanoparticles are incorporated throughout the coating to fight against infections. Currently, implant patients are subjected to an intense regimen of antibiotics to prevent infection immediately after surgery. However, the site of the implant will always remain vulnerable to infection.
But by incorporating silver into the coating, the silver particles act as antimicrobial agents as the amorphous layer dissolves, Rabiei says. This not only limits the amount of antibiotics patients will need following surgery, but provides protection from infection at the implant site for the life of the implant.
Moreover, the silver is released more quickly right after surgery, when there is greater risk of infection, due to the faster dissolution of the amorphous layer of the coating. Silver release will slow down while the patient is healing.
“That is another reason why we call it smart coating,” Rabiei says.
The research, “Functionally graded hydroxyapatite coatings doped with antibacterial components,” was co-authored by Rabiei, former NC State Ph.D. student Xiao Bai, and Oak Ridge National Laboratory researchers Karren More and Christopher Rouleau. The research is published online by Acta BioMaterialia.
Source: North Carolina State University