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Spider Silk: The Key to New Bone Repair Composites!

Apr 26, 2018

The researchers invented a biodegradable composite made of silk fibers that can be used to repair fractured load bearing bones without producing complications like other materials.


A three-dimensional rendering of a new type of bone repair composite developed by Niederich University. The composite material is made of silk fiber and polylactic acid fiber, and while maintaining flexibility, it is coated with excellent bioceramic particles. This biodegradable composite can help to heal bone without producing complications like metal parts.

Repairing major load-bearing bones such as leg bones can be a long and difficult process.

Repairing major load-bearing bones such as leg bones can be a long and difficult process.

To facilitate repairs, doctors sometimes install a metal plate to support the bone when it is healing. But this may be a problem. Some metals inject ions into the surrounding tissue, which causes inflammation and irritation. In addition, the metal is also very hard. If a metal plate is subjected to excessive loads in the legs, the new bones may become more fragile and more likely to fracture.

In order to find a solution to this problem, material scientist and biomedical engineer Professor Mei Wei turned to spiders and moths for inspiration. Wei is particularly concerned about silk fibroin, a protein found in the silk fibers of spiders and moths, known for its good toughness and tensile strength.

The medical community has long been aware of the existence of silk fibroin. Due to its high strength and good biodegradability, it is a common component of medical sutures and tissue engineering. However, no one tried to make it a dense polymer material, and Wei knew silk fibroin was the key if she wanted to make a better device to repair fractured load bearing bone.

In collaboration with Prof. Dianyun Zhang, a mechanical engineer at the University of Connecticut, Prof. Wei’s laboratory began testing silk fibroin in various composite materials by finding the right combination and ratio of different materials to achieve the best strength and flexibility. Sex. The new composition of course needs its high strength. Hardness. However, it does not need to be too high. If the hardness is too high, it will inhibit the growth of dense bones. At the same time, the composite material needs to be flexible so that the patient can heal the bone while still maintaining its natural range of motion and movement.

After dozens of tests, Wei and Zhang discovered what they were looking for. The new composite material consists of filament fibers and polylactic acid fibers (a biodegradable thermoplastic made from corn starch and sugar cane), impregnated in solution, and each solution is coated with hydroxyapatite. Fine microbial ceramic particles (calcium phosphate minerals found in teeth and bones). The coated fibers were then layered on a small steel frame and pressed into a dense composite rod in a hot compression mold.

In a recent study published in the "Mechanical Behavior of Biomedical Materials," Wei reported that high-performance biodegradable composites exhibit high strength and good flexibility, which is the same type of biomaterials in the literature. The highest value ever recorded. In addition, their performance will become even better.

Wei, who is also an associate dean of the School of Engineering and has been devoting himself to research and postgraduate education, said: “Our results show that this new type of composite material has very high strength and flexibility, but we think that if we can make every component To achieve our goal, we will get better results."

The new composite material also has toughness. The femurs of adults and the elderly may take months to heal. The composite material developed by Wei's laboratory completed its work and then began to degrade one year later. No surgical removal is required.

Joining Wei and Zhang's research team are Bryant Heimbach, a doctoral student and materials scientist at Wei Lab and Beril Tonyali from UConn who is studying materials science and engineering degrees.

The team has begun testing new derivatives of composites, including those that use the single crystal form of hydroxyapatite for more strength compounds, and a change to a coating mixture to make it have more weight in bones Maximized mechanical propertie