The golden silk orb-weaving spider (Nephila clavipes) excretes web threads powerful enough to capture small birds, and engineers at the Massachusetts Institute of Technology (MIT) want to replicate this feat of strength. Manufactured spider silk could revolutionize artificial tendons and ligaments, sutures, parachutes and bulletproof vests—if scientists could discover how a protein and water gel becomes a durable waterproof thread.
The slippery silk solution consists of 30-40 percent complex, tangled polymer molecules. As spiders squeeze the solution through an S-shaped canal, the thread molecules become aligned and the viscosity drops by a factor of 500 or more. Spiders stretch the liquid using their legs, weight and gravity to create filaments that rival the durability of most manmade substances. As the filaments dry, they become reinforced and strengthened with crystalline structures and become impervious to moisture. MIT’s Engineering Department is working with MIT’s Institute for Soldier Nanotechnologies to research the polymers, “enabling us to successfully process novel synthetic materials with mechanical properties comparable to, or better than, those of natural spider silk,” says Gareth H. McKinley, MIT professor of mechanical engineering.