How spiders and silkworms manage to produce strong fibers without clogging their silk-producing glands has puzzled scientists for years. While trying to mimic the process in the lab, researchers at Tufts University in Medford, Mass., stumbled across the answer.
David Kaplan and Hyoung-Joon Jin took natural silk from a silkworm, extracted the silk proteins known as fibroins, and dissolved them in water. The researchers then added increasing amounts of polyethylene oxide, a polymer that gradually removed water from the solution. As water volume decreased and the concentration of fibroin increased, the proteins folded in on themselves, forming round structures called micelles. Measuring between 100 and 200 nanometers in diameter, each micelle had a hydrophobic (water-avoiding) interior and a hydrophilic (water-seeking) surface.