Graphene-fed spiders spin bionic silk

Natural spider silk is already amazingly strong stuff, plus scientists have developed synthetic versions of the material. Now, however, Italian and British researchers have split the difference, in a manner of speaking – they've created silk that comes from spiders, but that has added man-made ingredients which give it extra strength.

Led by Prof. Nicola Pugno from Italy's University of Trento, the scientists fed "special" water to three species of spiders. What made it special? Dispersed within it were microscopic flakes of graphene, or carbon nanotubes (which are made of rolled-up sheets of graphene). Taking the form of a one-atom-thick sheet of linked carbon atoms, graphene is currently the world's strongest material.

When silk was subsequently gathered from the spiders, it was found that the graphene/nanotubes had been passed into the fibers. As a result, its tensile strength and toughness were much higher than that of regular spider silk.

"We found that the strongest silk the spiders spun had a fracture strength up to 5.4 gigapascals (GPa), and a toughness modulus up to 1,570 joules per gram (J/g)," says Pugno. "Normal spider silk, by comparison, has a fracture strength of around 1.5 GPa and a toughness modulus of around 150 J/g.

"This is the highest fibre toughness discovered to date, and a strength comparable to that of the strongest carbon fibres or limpet teeth," he adds. "These are still early days, but our results are a proof of concept that paves the way to exploiting the naturally efficient spider spinning process to produce reinforced bionic silk fibres, thus further improving one of the most promising strong materials."

A paper on the research was recently published in the journal 2D Materials.