The process of mending broken bones can be long and difficult. Load-bearing bones sometimes require a metal plate for support, which can lead to other problems such as irritation and rigidity.
Researchers at the University of Connecticut decided to turn to nature for a solution. Led by Professor Mei Wei, the team investigated silk fibroin, the silk fiber spun by spiders and moths known for its tensile strength and durability. Naturally biodegradable, silk fibroin is already used in medical sutures and tissue engineering.
Wei and her team developed a dense polymer composite using the silk fibers. Different composite forms
were tested to determine a combination of different materials that was both suitably strong and stiff and at the same time flexible, to allow patients to retain their natural range of motion during the healing process.
The resulting composite consists of long silk fibers and fibers of polylactic acid, a biodegradable thermoplastic derived from cornstarch and sugar cane. The fibers are dipped in a coating solution of fine bioceramic particles made of hydroxyapatite, the calcium phosphate mineral found in teeth and bones. The coated fibers are then packed in layers on a small steel frame and pressed into a dense composite bar in a hot compression mold. The composite begins to degrade after the bone is healed and surgery is not required to remove it.
For more information, visit www.today.uconn.edu.