Spider silk made from “hierarchical protein assemblies”
Research brings fabrication of steel-tough flexible fibres nearer. Samantha Page reports.
Scientists studying black widow spiders (Latrodectus mactans) are closer to understanding, and potentially replicating, how spiders turn proteins into super-strong, flexible fibre for their webs.
A new study, published in the journal Proceedings of the National Academy of Sciences shows it’s not a simple process. Spiders use a “hierarchical protein assembly,” first creating complex protein molecules, which are then spun into silk.
“We now know that black widow spider silks are spun from hierarchical nano-assemblies, 200 to 500 nanometers in diameter, of proteins stored in the spider's abdomen, rather than from a random solution of individual proteins or from simple spherical particles," explains corresponding author Gregory Holland of San Diego State University in the US.
Scientists had previously identified what amino acids make up spider silk and how it is structured, but how, exactly, spiders make their silk has remained elusive.
The study’s authors resorted to nuclear magnetic resonance (NMR) spectroscopy, which is used in MRI scans, as well as electron microscopy to look inside the spiders’ silk glands.
“The knowledge gap was literally in the middle," says co-author Nathan Gianneschi of Northwestern University in Chicago, USA.
“What we didn't understand completely is what goes on at the nanoscale in the silk glands or the spinning duct – the storage, transformation and transportation process involved in proteins becoming fibres.”
Spider web silk is as strong as steel, but light and flexible, making it a highly desirable material – if it could be effectively synthesised.
“One cannot overstate the potential impact on materials and engineering if we can synthetically replicate this natural process to produce artificial fibers at scale,” Gianneschi notes. “Simply put, it would be transformative.”
Last year, another set of researchers produced a kilometre of spider-like silk that was “almost as strong as the real thing” out of just a fraction of a gram of protein.