The silk spun by spiders has long entranced human engineers who've yet to fully grasp how to artificially create this strong, fine fiber. But new research shared at the American Chemical Society (ACS) Fall 2020 Virtual Meeting & Expo suggests we can recreate it via mixing silk with synthetic polymers — which might lead to structures capable of replacing cartilage cushions in the knee.
Combining silk with composite polymers might create advanced medical materials
"Silk has great potential for use in biomedical applications," said the projet's principal investigator Juan Guan, who holds a doctorate. "Silk is versatile, and the human body tolerates it quite well, and can even degrade and absorb it."
Silk and medicine have a long-standing relationship. Ancient doctors' records are replete with accounts of stitching patients up with fibers spun by silkworms, and date back almost 2,000 years. Modern surgeons finish some surgeries, like on the eye, with silk sutures.
The scientists discovered how combining synthetic polymers with silk might procure versatile new materials with ample applications in medicine, and potentially other fields.
Longer silk fibers better than shorter strands
Of course, other researchers have developed composite materials with silk, but they typically worked with short fibers or only the primary protein contained in silk.
Guan, on the flip side, focused on silk fabrics woven from long, single threads. Cocoons of silkworms sometimes contain fibers almost 5,000 feet (1,524 meters) long, and it can more effectively distribute mechanical stress when used in fabric than we can expect from shorter, discrete strands, added Guan.
In their studies, Gran's team used silk from common domesticated silkworms belonging to the species Bombyx mori, and also stronger, more elastic fibers from the wild Antheraea pernyi species.
The researchers conjoined this fabric with a polymer matrix, typically an epoxy, which is common in adhesives. When combined, the fabric and polymer create a laminate — like the durable surface covering on furniture — and is then cut into the shapes researchers desire.
New biomedical materials may help vertebrae fuse better than metal
This is significant because these properties might lead to new materials capable of integrating more successfully within the human body than present-day materials. For example, Guan and her team are collaborating with orthopedic doctors to develop structure shaped like cages to temporarily hold vertebrae in place while they fuse following major surgery.
This is a role typically filled with metal, but the hardness and stiffness of silk composites is more compatible with bones, which could make them a more resilient and comfortable alternative to clunky metal structures, said Guan.
While there are many challenges to bringing silk composites into the surgical ward of major hospitals, it's interesting to know that one of the most mystical substances produced by other species of life is serving to advance the future of biomedical technology.