A web of possibilities: Utah researcher uses goats to make one of the strongest known substances
Lewis has managed to gain $3.2 million in research grants and was recently awarded another $40,000 from the state in a Technology Commercialization and Innovation Program grant. His technology has also gained the interest of the National Institutes of Health, the U.S. Air Force, Department of Energy, National Science Foundation and U.S. Department of Agriculture.
Silk from milk
Lewis's goats are milked about twice a day; however, there are a lot of other components from the milk that need to be removed in order to isolate the two key proteins that make spider silk. The goats are separated into two groups, each group contains one of the two proteins to make the silk, so the proteins must be extracted and then combined.
The milk is frozen and the cream is separated, which removes most of the fat but not all of it. The thawed milk is then pushed into a micro filter that blocks the larger fat molecules and lets the smaller proteins through. A smaller, more refined, filter then further isolates the silk proteins. "When we dry it, it looks like a white powder," Lewis said. Still, the challenge remains: how do they take a powder and spin it into a fiber, like a spider does?
Spinning silk into gold
"We've been able to somewhat duplicate that," Lewis said, but for now spiders remain the masters. On average, spiders can spin six different types of fibers with various properties. Lewis' team has managed to spin a fiber similar to a spider's suspension line, which is the thicker of the fiber types.
The two proteins are combined into a solution and pushed into a needle, but a spider pulls the silk out of its spinners, where a syringe would push it out. So lab workers tease the silk out of the needle and then pull it out like a spider. "They pull it out like floss, not push it out like toothpaste," Lewis said.
What they get is a fiber that is incredibly strong, amazingly light-weight and very versatile. In current medicine, doctors take a torn ligament or tendon and carefully sew it together, providing a less-than-durable treatment. Lewis said silk is very compatible with the human body and can be used as temporary tendons and ligaments while providing a scaffolding for the body to begin healing the tear together. "Right now there's nothing out there that can do that," he said. Silk can also be used to suture damaged eyes, or even nerves.
The military is interested in spider silk to manufacture better parachutes and cables, providing much more strength for the same amount of weight of current materials. Even auto manufacturers are interested in silk to provide safer air bags. Lewis said one feature of spider silk is that it absorbs energy better. Current air bags can knock children and adults back into their seats when deployed, causing possible injury. Lewis said studies show spider silk appears to better absorb energy and would minimize such knock-back.
With the support of USU, Lewis said he expects more commercial interest will emerge in the near future.
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