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August 17, 2020

Silkworm silk shows promise for durable medical implants

By Ellen Daniel

Silk made by silkworms could be used to create durable medical implants, researchers have found.

Silk is a strong and versatile material, with spider silk being five times stronger than steel of the same thickness. Scientists have therefore been trying to recreate its properties for many years and silk sutures are already used in some surgeries.

Researchers at Beihang University have developed a composite material, comprising of silk and synthetic polymers, that is safe for use in the human body and can be used in medicine, and hope that in the future it may be used to create medical implants.

“Silk has great potential for use in biomedical applications,” says Juan Guan, PhD, the project’s principal investigator. “Silk is versatile, and the human body tolerates it quite well, and can even degrade and absorb it.”

Other researchers have developed composite materials using silk, but they have often used short fibres or the the material’s primary protein. However, by working with a long, single thread, the researchers at Beihang University have created a more durable material.

This is then combined with a polymer matrix to form a laminate, that can then be cut to the needed shape.

The researchers believe that the new material could have applications for patients who have undergone surgery. They are working with orthopedia doctors to create cage-like structures that could be used to temporarily hold vertebrae in place while they heal. Metal is currently used for this purpose but the new material’s hardness and stiffness makes it similar to bone, making it potentially more suitable and comfortable.

Although real-world applications are still several years away, researchers also believe that the technology could be used to create replacements for the cartilage cushions in the knee.

However, the researchers have encountered some challenges when developing the new material. For example, silk can be weakened when exposed to moisture, so they tested how well the silk composite materials survived in humid conditions. They found that while the experiments showed that the stiffness of the material did decrease, it was still able to function effectively.

In addition, the body cannot break down and absorb the epoxy, meaning it is not suitable for implants intended to dissolve.

Researchers are now exploring combining silk with other types of fibers. In a recent study, they added carbon fibers to create different properties.

“The notion of hybridizing silk with other fibers makes it possible to produce a rather nice spectrum of properties that you can optimise for a given application,” said Robert Ritchie, PhD.

The research will be presented at the American Chemical Society (ACS) Fall 2020 Virtual Meeting & Expo.

Read more: Researchers develop cybernetic coatings for interfacing hardware and human tissue.