[Image above] Credit: Alan Reeves; Flickr CC BY 2.0
The struggle is real for scientists on a mission to bring the numerous benefits of spider silk to the masses. Turns out that it’s tough to spin (pun totally intended) this strong fiber synthetically in the lab and mimic the impressive strength and durability of the real thing.
Not to mention that naturally sourced spider silk isn’t cheap to produce in large quantities, because spiders are a little bit prickly to work with due to their territorial and cannibalistic nature (i.e., farming them en masse is tricky). Besides, our eight-legged friends can only produce so much of the stuff at a time. Like you and me, they aren’t machines.
Moreover, it’s impractically slow to harvest spider silk from the natural source. The Oxford Silk Group in the Department of Zoology at Oxford University in England studies the biology of silks. It demonstrates, in the video below, how spider silk is pulled by tweezer from the spinnerets and attached to a spool with a dab of glue, after which a motor is started to begin harvesting. The group says it’s possible to harvest only about 30–80 meters of silk per session before the spider needs to be released back to its web to rest.
Credit: OxfordSilkGroup; YouTube
But an exciting breakthrough has emerged. After five years of diligent-but-quiet research, Bolt Threads, a startup based in Emeryville, Calif., says it has finally made “meaningful progress” on the challenge of developing synthetic spider silk for commercial use, according to a recent Wired article.
And they have support from notable financial backers for development, too—a lot of support—in the amount of $40 million in investments and government grants, including a chunk of change from the National Science Foundation.
“Basically, our mission from the beginning was to make a scalable amount of spider silk and bring that to consumers. It’s a problem that’s been around for a long time, and has been hampered entirely by technical challenges,” Dan Widmaier, CEO of Bolt Threads, tells Wired.
What the company is doing isn’t groundbreaking in the biotechnology world, though, Widmaier says in the article. He summarizes the process as follows:
“The scientists genetically engineered a microorganism that can yield large quantities of silk protein through a yeast fermentation process—not just grams of silk protein, but metric tons. Then, using a proprietary mechanical system, a wet silk protein solution is manually squeezed through small extrusion holes and goes into a liquid bath that turns the stuff into solid fibers.”
While Widmaier didn’t divulge specifics, he did tell Wired “the extrusion process mimics the behavior of a spider’s spinneret—its silk-spinning organ.”
So how do spiders produce silk anyway?
Spiders store gel-like silk proteins—also known as spidroins—in their glands. But exactly how spiders convert these proteins from a soluble state into a solid fiber was a relative mystery until Swedish researchers published findings in the journal PLOS Biology in August 2014 that revealed a gradual change in pH occurs as the proteins travel through the glands, which triggers the solidification.
What makes spider silk so amazing? Cheryl Hayashi, professor of biology at the University of California, Riverside, describes her research on spider silk on the TED stage, and points out that spiders have been around for nearly 380 million years and can be found on almost every terrestrial habitat on the planet. Not to mention there are 40,000 species of spiders, and they all make silk at some point in their lives. Silk is crucial to their survival—for shelter, safety, reproduction, and catching prey. And the coolest part? Hayashi says her research shows that almost all types of spider silk surpass the strength of some of the strongest types of fibers known to modern technology—like nylon, wool, Kevlar, and carbon. These alluring properties fascinate scientists in the biomimetics field, who turn to nature to find inspiration for solving complex materials challenges.
Credit: TED; YouTube
For its size, spider silk is stronger by weight than high-grade steel, but it’s incredibly flexible and light. It even surpasses the elasticity of rubber.
If commercialized, synthetic spider silk could be a real game changer when it comes strengthening materials for things like bulletproof vests, biodegradable water bottles, flexible bridge suspension ropes, vehicle air bags, and protective cases and covers for electronics. And that list is just the tip of the iceberg.
But the researchers at Bolt Threads aren’t the only ones pioneering the spider silk revolution. Scientists at the University of Trento in Italy have been spraying spiders with water containing carbon nanotubes and graphene flakes to produce “one of the toughest fibers ever measured” by materials science standards, according to a recent MIT Technology review article. Move over, Kevlar!
How do you think the advent of mass-produced synthetic spider silk will advance technology? Share your thoughts in the comments!