Press Release: Processed Silk
Flaws of Processed Silk Revealed at the Molecular Scale
The strong fibers made by silkworms and spiders are the basis for new green materials to replace plastics and other materials. Using a powerful microscope, researchers now visualized at the level of individual molecules how processed silk behaves different from its natural counterpart.
The silks spun by the silkworm (see figure, panel A) are mass-produced in Asia not only to make appealing fabrics; they are also the basis for novel materials developed in research labs around the globe. Silks are interesting because they are strong, yet sustainable and environmentally benign. Unlike synthetic plastics they are not based on oil, nor does their production require much energy or any toxic substances. And being of biological origin they are even good for medical applications. Primarily the silk from the silkworm is currently used to develop medical and engineering applications, such as brain implants, because it is the only silk available at large amounts.
Researchers from The College of William & Mary have now revealed how processing diminishes the outstanding properties of natural silk. Hannes Schniepp and his team at William & Mary showed in collaboration with silk expert Fritz Vollrath from Oxford that natural silks first form intriguing, tiny fibrils when spun. Using a microscope powerful enough to visualize individual molecules, the team showed that these fibrils have a cross section about 16 million times less than a human hair (see figure, panel C). These tiny fibrils are a crucial ingredient of silkworm fibers, as they contribute to their strength and toughness. The team’s new study, to appear in the journal Biomacromolecules on August 18, shows that the most common way of processing silk — dissolving silkworm cocoons (some cocoon specimens are shown in the figure in panel B) — inhibits this fibril formation (as shown in the figure in panel D: no fibrils). This helps to explain why artificial silks often fail to show the strength of their natural counterparts. Hence, the new analysis method developed by the William & Mary team is an important step toward the development of processing methods for better synthetic silks.
Media Coverage of This Work
|Oct 2015||Our research on the silk of the brown recluse spider is highlighted by the ideation magazine article: "Unraveling the secret of silk that's more alive than dead".|
|Sep 2015||Cover Story in the Daily Press featuring our recently published research on shear-induced self-assembly of molecularly thin silk fibrils. There is also a corresponding Video Interview.|
Our Related Publications
||| Biomacromolecules (2015) — Koebley, Greving, Vollrath & Schniepp*
"Silk Reconstitution Disrupts Fibroin Self-Assembly"
||| Adv. Materials (2013) — Schniepp*, Koebley & Vollrath
"Brown Recluse Spider's Nanometer Scale Ribbons of Stiff Extensible Silk"
||| Biomacromolecules (2012) — Greving, Cai, Vollrath & Schniepp*
"Shear-Induced Self-Assembly of Native Silk Proteins into Fibrils Studied by Atomic Force Microscopy"