What's stronger than Kevlar, stretchier than nylon, and a natural material that has long intrigued scientists and engineers because of its potential medical applications? The strongest of the six types of spider silk, referred to as "dragline" silk, is used for outer circles of a web, or for repelling from ceiling to floor.
In the early '90s molecular biologist Randolph Lewis and his colleagues at University of Wyoming in Laramie identified the two proteins that make up the strong silk, but the large size of the proteins made the attempts to mass-produce the silk from spiders unsuccessful. Cannibalistic spiders also aren't the ideal animal to farm commercially for the quantities needed, so the researchers have experimented with inserting the silk-producing genes into the genome of animals including cows, hamsters, and most recently, goats.
Lewis recently left Wyoming for an endowed position at Utah State University (Logan, UT) where he continued his research using goats, because of their manageable size, friendliness, and faster speed from birth to lactating age. The silk gene is implanted into a goat embryo, and the goats' milk is the source of the spider silk protein. The proteins are purified from the milk, which is dried down and redissolved to get material that can be spun into fibers.
The elasticity and strength of spider silk make it a material that could be used for artificial ligaments and tendons, or for sutures in ophthalmic and micro surgery. Lewis estimates that a week's worth of milk from one goat would provide enough silk protein for one single tendon or ligament replacement surgery. Extensive animal testing would come before any surgery on a human subject, which is years away from reality.
Lewis currently has 34 goats altered with the spider silk gene, including 20 milking females, two of which are currently lactating. The hope is that the spider silk research will lead to commercial products in the future, which will benefit Utah's economy and potentially create jobs.