Paging Peter Parker: Scientists have taken another step closer to producing viable artificial spider silk by zooming-in on the nanoscopic structure of the natural, spider-made stuff, using the brightest X-ray beams in the Western Hemisphere.
And as it turns out, despite the intricate and deliberate patterns woven by common orb spiders, the strongest part of their silk — the threads called dragline silk, which are used to create the scaffolding of the entire web — are mostly made up of extremely random and disordered atoms on the nanoscale, according to the results of a new study by scientists in Arizona and Illinois.
In fact, between 85 and 90 percent of orb spiders’ dragline silk fibers are “amorphous regions,” comprised of random, disorganized atoms, which researchers believe are responsible for providing the silk with its extreme elasticity.
The remaining 15 to 10 percent of the silk is a highly-orderly crystalline lattice structure of atoms which gives the silk its amazing strength — as strong as steel.
See the difference between the orderly regions (multicolored) and random amorphous (blue) in the following image of X-ray data provided by Argonne National Laboratory in Illinois, where the study took place.
“These techniques we develop are getting us closer and closer to know the exact molecular structures within natural spider silk,” said Jeff Yarger, a biochemistry professor at Arizona State University and one of the lead researchers of the study, in an email to TPM.
“This knowledge is required in order to develop synthetic spider silk,” Yarger added.
Scientists have already managed to bioengineer spider silk out of silk worms and goats’ milk, but as Yarger pointed out, they aren’t quite as good as the spider-made silk.
“The problem is that these synthetic silks do not form the correct secondary and tertiary structures that natural spider silk fibers form,” Yarger told TPM.
The thought is that by getting a better view at what makes up real spider silk, scientists will be able to better replicate it on their own.
“Previously scientists had concentrated on the more ordered crystalline regions even though they form a minority of the fiber,” said Chris Benmore, an X-ray scientist on the project, in an email to TPM.
Benmore works specifically at the Advanced Photon Source (APS), the high-powered x-ray facility used to get the new close-up of the spider silk. The APS is a synchrotron facility — a giant particle accelerator measuring over a half-mile around, located at the Argonne National Laboratory in Argonne, Illinois, near Chicago and funded by the Department of Energy.
Scientists from around the country and the globe are allowed to use the x-rays for their own research projects. As Argonne explains, the APS is “open to everyone who has a need for extremely brilliant x-ray photon beams.”
In this case, the APS high-energy X-rays allowed Yarger and his colleagues to achieve an unprecedented level of detail when it came to imaging the amorphous regions of spider silk, zooming in to 10 million times magnification.
“We have recently developed a very powerful high energy x-ray probe at the APS which does not destroy the sample (which is a problem with lower energy x-rays) and provides a detailed insight into both the amorphous and crystalline regions of the spider silk,” Benmore explained.
The results of the X-ray study were published in a paper in the journal Physical Review Letters in late April.
