UCR Assistant Professor of Biology Cheryl Hayashi can imagine the day when spider silk is part of a wide variety of everyday products.
Be it artificial tendons repairing a weekend warrior’s torn ligaments, lightweight body armor shielding cops and soldiers from the perils of their work or the ultra snug, sleek body suits coating the finely tuned bodies of Olympic athletes, spider silk shows potential.
“I think there’s a spider silk out there for all these applications,” she said. Of course, these products aren’t going to hit Olympic arenas or the mean streets of L.A. and Baghdad anytime soon, but they’re coming, Hayashi says.
Materials scientists have long viewed spider silks with great fascination because of their extraordinary properties. One-tenth the diameter of a human hair, lighter than cotton, yet ounce for ounce up to five times stronger than steel and more flexable than nylon, the attributes of spider silk make it a tantalizing material.
“It’s not that there’s one spider silk that’s going to do all these things,” Hayashi noted. “The value of the spider silk system is that spiders have evolved to have different kinds of silks.”
Of the seven spider-produced silks, egg case silk, which is waterproof, durable and possibly antimicrobial and protects developing offspring, is among the most intriguing, Hayashi says.
So why haven’t we seen more progress toward Space Age products based on spider silks? The challenges are considerable. Spiders cannot be mass reared in a lab or on a farm because they are territorial predators, posing worker turnover problems.
Then there’s the bottleneck between producing silk proteins and actually making a fiber. Biotechnology has allowed us to turn goats and cows into silk producers to increase the supply. But because the process that the spider uses to transform her liquid proteins into a solid fiber is still not fully understood, there’s a scarcity of the gossamer strands.
“I find it absolutely fascinating, because everybody has spiders in their homes . . . and just the idea that all those little animals are doing something that people spend millions of dollars trying to copy is mind-boggling,” Hayashi said.
Then there’s the scarcity of knowledge. In August, when Hayashi and postdoctoral researcher Jessica Garb published a paper in the Proceedings of the National Academies of Science (PNAS), they were covering new ground. It’s that trail-blazing nature of spider silk research – and its potential for space-age product development – that fuels Hayashi’s and Garb’s investigations and makes each discovery exciting.
“That’s part of the reason why the (PNAS) paper kind of made a splash. It was the first time there was a characterization of egg case silk from many different spiders, which really hadn’t been done before at the molecular level,” Garb said.
Hayashi and Garb’s cutting-edge research may someday spur product-development efforts on egg case silk to approach that of dragline silk, those I-beams of spider web architecture. Dragline silks form the radiating ribs of what we commonly think of when we think of spider webs. Spiders also use it to lower themselves from webs and guide themselves from place to place.
In 2002, the Canadian biotechnology company Nexia and the U.S. Army authored a paper in the journal Science, reporting they had produced and spun the first manmade fiber with mechanical properties similar to that of natural dragline silk. They used goats to produce the silk protein in their milk and developed a means to mimic how spiders spin the strands.
This wonder-product research, however, isn’t possible without the efforts of those like Hayashi and Garb, who push the envelope of knowledge in new and exciting ways. An important part of their work is tracing spider evolution to today’s more than 37,000 species.
“The approach I’m taking is ‘let’s see what’s gone on over 400 million years of evolution.’ That’s a lot of time and a lot of experimentation that’s gone on,” Hayashi said.
From her lab at UC Riverside’s Spieth Hall, Hayashi and her research group are one of several teams scattered throughout the world laboring to unlock the mysteries of this fiber through its genetics.
Many of today’s spiders use a genetic silk recipe that emerged at about the time of the dinosaurs, some 125 million years ago. Orb weaving spiders have stuck to that recipe ever since.
The development of Hayashi’s spider silk studies began at childhood in the lush environment of Hawaii, which awakened her love for biology. She describes Hawaii as “a stellar natural laboratory for evolution,” which focused her interest on evolutionary biology.
Her interest in spiders took hold as an undergraduate student at Yale University with a job feeding a researcher’s spider colony.
“They have to be fed live food, and so I got that job,” she said. “And then I was given a summer research position to go to Panama and study spiders in the tropics and I just jumped at the opportunity.
“You don’t work on spiders for very long before you start getting really curious about their silk, because silk is just an integral part of their lifestyle.”
Hayashi received her Ph.D. from Yale in 1996. Her enthusiasm impressed molecular biologist Randy Lewis, with whom she did postdoctoral work at the University of Wyoming.
“Cheryl was simultaneously the hardest working and most efficient person I have been associated with,” he said. “Her work on the flagelliform silk gene, which was published in Science (February 2000) was an example of that.”
Hayashi’s enthusiasm has also touched her students at UCR.
“I had Cheryl for an evolutionary biology class and she made the subject so interesting I had to try to get a position in her lab,” said Teresa DiMauro, a fourth-year biochemistry major at UCR. “I mean, these were some long classes, an hour and a half twice a week and I swear I was never bored.”
DiMauro has been working in Hayashi’s lab since June.
Hayashi credits the spider’s charms, rather than her own efforts, with capturing the imaginations of her students.
“It usually doesn’t take very much,” she said. “If you show them the amazing properties of these silks – how some silks are stronger than steel, how some silks can absorb more energy than Kevlar – if you show them properties like that, that definitely catches their attention.”
Whatever the source, spider silk has turned some heads.