It’s the hunt for spider silk – and an efficient way to make a lot of it – that has evaded researchers for the last two decades. But why are they after spider silk?
As Professor Randy Lewis of Utah State University puts it, it’s the “ancient biomaterial of the future.” Spiders have made their silk for 400 million years, and we’re just now beginning to realize just how strong, absorbent and useful it is.
Spider silk is better than Kevlar at stopping bullets and has a tensile strength greater than steel’s. Here’s a breakdown of a few of the industries in which spider silk can be used:
Medicine As far as researchers can tell, spider silk is all but invisible to the human body, meaning that our immune systems won’t reject it as they occasionally do with other substances. This makes the elastic and tensile properties of spider silk perfect for making artificial tendons, cartilage and ligaments as well as sutures and sealants. Prototypes of these already exist.
Military As we saw while shooting this story, a layered piece of rubbery silicone with 10 layers of spider silk painted on was enough to stop a bullet. Without those incredibly thin layers of spider silk, the bullet went right through. Properties like this make it an excellent candidate for body and vehicle armor.
Sports Spider silk proteins, when painted as a sheet, have incredibly absorbent qualities for dissipating impact and shock, like from bullets. This could translate to football helmets that protect our heads better than any before.
Automotive Tires and airbags are standard in every vehicle and could soon incorporate spider silk protein to make them stronger and lighter than ever.
The list goes on, from personal beauty products to clothing. Considering how large those industries are, it’s no wonder many have tried (and some have failed) to find a way to make a lot of it.
So why is has it been so difficult? For one thing, you can’t farm spiders like silkworms for large-scale silk production. As University of California at Riverside’s Cheryl Hayashi told us, “It would be like trying to rear and farm tigers.” Because spiders are predatory, “They are not very easy.”
You can get almost 100 meters of silk from a single black widow, but if you tried to get a commercial useful amount of silk from a lot of spiders, they would eat each other, and it would take an incredibly long time to harvest.
Researchers in the mid-1990s started to look elsewhere — to transgenic goats, alfalfa and bacteria. They uncovered the genes that code for silk proteins and were able to place those genes in organisms like goats and, through an impressive feat of science, get spider silk protein to come out with the goats’ milk.
While making larger quantities of artificial spider silk is already a reality, getting it to a commercially viable level, at which vast amounts can be consistently produced, is not.
The difficulty lies in finding the right gene to code for the right type of silk protein (each spider makes several silks, with different tensile and elastic properties) and in finding the most efficient way to get other organisms to make a lot of it, whether goats, plants or tankfuls of E. coli.
For the time being, our spider-silk-filled reality remains science fiction, but Hayashi is convinced we’re close to a giant leap forward. “Someone’s going to make the breakthrough tonight. I always believe that. It’s just a matter of a short amount of time.”