Silk Harnessed to Build Implantable Medical Devices

Silkworms are known for their contribution to scarves, ties, and sarees everywhere. But the natural qualities of silk allow it to be used to make implantable optical sensors and other devices that don’t produce an immune response, while being biodegradable by the body over time.
The MIT Technology Review profiles the work of Associate Professor Fiorenzo Omenetto at Tufts University’s Department of Biomedical Engineering:

Omenetto’s recipe begins with cocoons spun by the silkworm Bombyx mori. First, he says, “you cut the cocoon and remove the worm–much to the chagrin of vegans.” Senior research technician Carmen Preda then boils the cocoons in a solution containing the salt sodium carbonate. This helps dissolve sericin, a gluey glycoprotein that holds the cocoons together but causes immune reactions in humans. After the silk fibers dry, they’re dissolved in a solution of lithium bromide. When it cools, Preda uses a syringe to load it into a dialysis cartridge. She sets this inside a beaker of water, which draws out the salt.
What’s left in the cartridge is a clear, viscous solution of the purified protein silk fibroin. Preda removes this silk “syrup” from the cartridge with a syringe and loads it into a row of test tubes; this is the starting material for Omenetto’s optical components. If he wants to use the components in a biosensor, he can add a protein targeting a particular molecule–say, oxygen-binding hemoglobin–at this stage. “You have this nice water-based solution that you can mix anything into,” Omenetto says.

Dr. Omenetto describing his new manufacturing technique: