Silk is one of the toughest materials on earth and is also smooth to the touch. It is one of the most effective polymers, which is why its use in engineering and medicine is growing day by day. Silk was the basis for the original bullet proof vest and a derivative, synthetic form is still used in Kevlar vests. Now they might be able to mend fractured bones as well.
To fix fractures, usually doctors screw in metal alloys that bear most of the weight but their composition and structure is rigid and inflexible, unlike bone which isn’t as stiff. An alternative is the biodegradable polymer, poly-lactic-co-glycolic acid. The problem with using it is that it causes inflammation and also the polymer is so soft, a hole has to be drilled in to the bone to make room for it.
All these options may be obsolete now that silk has entered the picture. Samuel Lin at Harvard Medical School and David Kaplan at Tufts University decided to experiment with it. They took silk from the cocoon of Bombyx mori Silkworms and dissolved it in alcohol. After that they poured the solution in to molds shaped like screws and baked the solution.
When the polymer was tested on rats with fractures, the screws adapted to the skeleton by carving their own threads and fitting in. The screws were undetectable in an X-Ray and they were flexible so more room for movement was allowed. The screws also degrade over time without causing inflammation. Its like having a plaster inside the body that needs no removal. With the successful experiment on rats, they are hopeful for positive results on humans in future cure.