Professor Fritz Vollrath and colleagues, in the Silk Research Group at the Department of Zoology, have been able to demonstrate that the spinning ‘dope’ or unspun silk behaves just like a traditional, commercial semi-crystalline polymer, as published today in Nature Materials. This discovery has important implications for industry in their attempt to spin artificial silk threads from protein feed-stocks.
The scientists took dope from the glands of spiders and silkworms, and subjected these precursor silks to shear forces similar to those they would encounter in the animals' spinning ducts. Surprisingly, both pre-silks behaved identically under shear, and both flowed easier the faster they were sheared. This is a phenomenon called ‘shear thinning’ and was first described in the 1920’s for molten plastics.
The observation that both silks – having originated separately and evolved over hundreds of millions of years of independent evolution - show identical shear thinning behaviour suggests the key importance of this flow -response for spinning in nature. Silks are spun with water as a solvent, as well as ambient pressures and temperatures, yet they are fibres with material properties that can put top commercial fibres to shame.
Professor Fritz Vollrath said: ‘Copying the spider's trick of making the silk proteins, and spinning them into these tough fibres has been a dream for a long time. The discovery that the spinning process relies on well understood flow physics is a further step towards realising this dream.’
Researchers from the Oxford Silk Group have previously been able to show that nature has evolved some clever tricks to facilitate the mechanics of the spider’s extrusion system.
Lead author Chris Holland, from the Oxford Silk Group, said:’ Using techniques originally developed for the physical sciences and applying them to study nature’s way of creating these high performance materials opens new doors into understanding not only how silks may have evolved, but also how we may take inspiration from them to improve our own materials‘.
Source: University of Oxford
Related stories:
For spider-strength silk go back to basics
If you want to spin silk like a spider then you need to rethink your starting material, Oxford University scientists have discovered.
Spider silks, the ecological materials of tomorrow?
Spider silks could become the intelligent materials of the future, according to a review article published this month in the journal Microbial Cell Factories. The characteristics of spider silk could have applications in areas ranging from medicine to ballistics.
This becomes possible because Hebrew scientists, for the first time anywhere, have succeeded in producing self-assembled spider web fibres under laboratory conditions, outside of the bodies of spiders.
Biologists unravel the genetic secrets of black widow spider silk
Biologists at the University of California, Riverside have identified the genes, and determined the DNA sequences, for two key proteins in the “dragline silk” of the black widow spider – an advance that may lead to a variety of new materials for industrial, medical and military uses.
Fascinating Spider Silk
Stronger than steel and more elastic than rubber: spider silk is unsurpassed in its expandability, resistance to tearing, and toughness. Spider silk would be an ideal material for a large variety of medical and technical applications, and researchers are thus interested in learning the spiders’ secrets and imitating their technique.
Engineers probe spiders' polymer art
A team of MIT engineers has identified two key physical processes that lend spider silk its unrivaled strength and durability, bringing closer to reality the long-sought goal of spinning artificial spider silk.
Genetic Engineering Fuses Spider Silk and Silica
Bioengineers at Tufts University have created a new fusion protein that for the first time combines the toughness of spider silk with the intricate structure of silica. The resulting nanocomposite could be used in medical and industrial applications, such as growing bone tissue.
Why spiders' silk threads don't twist
Unlike a mountain climber swinging from a rope, a spider suspended from its silk thread hardly ever twists. Although the flexibility and strength of a spider’s dragline outperforms the best synthetic fibres, surprisingly little has been published on the twist properties of the thread. A new study however, by a research team from Oxford and Rennes Universities, published in
Nature, reveals just how good the damping properties of spider silk are.
The high cost of low status
Feeling powerless can trigger strong desires to purchase products that convey high status, according to new research in the
Journal of Consumer Research.
