"We can play around with these modules and try to optimize structures for applications where you need unique specific properties—even those not found in natural silk," Scheibel said.
A range of products could someday ensue.
"I would start with something in the area of paper—paper that's strong, tough, can't be torn. For uses like banknotes silk could be a perfect material," Scheibel said.
"In the aircraft or automobile industry, think about a material that can absorb a lot of energy. If you have an accident [that causes a dent], it might be gone hours later, because the material can take up energy and reacquire its form. That's what happens to a web when an insect flies into the web."
Myriad of Potential Uses
Over hundreds of millions of years the 37,000 known species of spiders (and others unknown) have evolved and diversified many silks for their unique purposes. Best known and studied is silk secreted by a spider's major ampullate glands.
Orb-weaving spiders use this kind of silk like Spider-Man, as a dragline on which to make ascents and descents. The silk is also used to create spiders' familiar "wagon wheel" webs.
Spider silk has incredible tensile strength and is often touted as being several times stronger than steel of the same thickness. What's even more unique, however, is spider silk's elasticity.
"When we say spider silk is tougher than things like Kevlar [a plastic used to make body armor] that's what were talking about. Kevlar has higher tensile strength but it's not very stretchy," said Todd Blackledge, an entomologist at the University of Akron.
These properties suggest a potential for many applications for spider silk: extremely thin sutures for eye or nerve surgery, plasters and other wound covers, artificial ligaments and tendons, textiles for parachutes, protective clothing and body armor, ropes, fishing nets, and so on.
"One that's initially surprising is air bags," Lewis added. "Right now an air bag just sort of blasts you back into a seat. But if it were made out of this material it would actually be made to absorb energy and really reduce impact."
"Spidergoats"
Unlike silkworms, spiders tend to eat one another and cannot be effectively farmed. That's spawned a search for alternative silk sources. The most common method is introducing silk-spider genes into other organisms so that they can produce silk proteins that might later be used to create artificial silk threads. Host organisms range from simple bacteria to goats.
Quebec-based Nexia Biotechnologies created a stir in 2000 when it bred two "spidergoats" named Webster and Pete. The goats were altered with spider genes so that they could produce silk proteins in their milk. Nexia's artificial silk product is known as BioSteel, but the company is currently involved in a restructuring that has stalled research efforts.
Bacteria produce enough proteins for research work, but their long-term commercial production potential is unproven. Other efforts have focused on silk-producing plants such as tobacco or alfalfa and have met with some success.
But while producing spider-silk proteins is becoming more feasible, and scientists continually learn more about how to spin them into solid materials, major hurdles must be cleared before "spider products" become available.
So far, artificial fibers have lacked real spider silk's strength, and the artificial threads have been much wider than their natural counterparts. Before the advent of a spider-silk marketplace, human web weavers must close the technology gap on their arachnid counterparts.
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