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Posted on Oct 23, 2018
Scientists at Arizona State University are celebrating their recent success on the path to understanding what makes the fiber that spiders spin – weight for weight – at least five times as strong as steel. "Spider silk has a unique combination of mechanical strength and elasticity," says Jeff Yarger, professor in the School of Molecular Sciences.
One of the fundamental mysteries of spider silk, which has limited scientists' ability to produce artificial silks of the natural silks has been explained by researchers in ASU's School of Molecular Sciences in collaboration with a team from San Diego State University and Northwestern University.
Their results, published online today in the Proceedings of the National Academy of Sciences (PNAS) is entitled "Hierarchical Spidroin Micellar Nanoparticles as the Fundamental Precursors of Spider Silks."
Spider silk is an exceptional biological polymer, related to collagen (the stuff of skin and bones) but much more complex in its structure. The ASU team of chemists is studying its molecular structure in an effort to produce materials ranging from uses in civil and mechanical engineering to artificial, yet biocompatible, tendons.
"Everybody's familiar with silk, because they're familiar with silkworm silk. The silk trade has been around for a long time. But spider silk has a much larger variety in its properties, "explains Yarger.
Unfortunately, spiders do not produce silk in large quantities. "You can put lots of silkworms in a small area and genetically modify them to go from the larval state to a moth in 20-30 days. Spiders take longer. But let's get to the crux of it-spiders do not like each other. They eat each other, "states Yarger. This of course eliminates the possibility of farming them en masse.
Scientists have come up with ingenious ways to get around this problem. They have genetically engineered silkworms, E. coli, and even goats to produce spider silk. Unfortunately, while these organisms produce the same proteins, they do not have the same mechanical properties as the natural product. They are not so strong, for instance, or as flexible.
This is where the current research comes in – Professor Yarger was joined by Dian Xu, Samrat Amin and Brian Cherry, also of ASU, Associate Professor of Chemistry from San Diego State University, Gregory Holland, and Professor of Chemistry from Northwestern University, Nathan Gianneschi.
"In a matter of milliseconds, a spider can take a concentrated protein solution stored in its abdomen and pull this material rapidly through ducting and spinnerets to produce silk fibers," enthuses Yarger.
"Understanding at the molecular level how to perform this complex process, and reproducing it in the lab, is the primary research objective within our group."
The team employed NMR (or MRI) at ASU and San Diego State as well as cryo transmission electron microscopy at Northwestern University. They studied the precursor solution of the local silk dragline Black Widow (or Latrodectus Hesperus) spiders.
"We are now closer to a molecular understanding of this process," explains Yarger. We have discovered a hierarchical micellar nanoparticle based on the molecular organization of the stored proteins in the abdomen of spiders. This spider silk protein fiber formation and hopefully one step closer to the production of spider silk protein fiber. "
The Daily Galaxy via ASU
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