Spider silk has many fascinating mechanical properties which have attracted researchers’ attention. Now a team has matched one of nature’s wonders with graphene, currently the world's strongest material, thereby opening the door to a new class of bionic composites.
Spider silk provides a combination of great strength ~1.5 GPa and toughness ~150 J g−1. To explore what would happen to those measurements if the spiders ingested graphene, researchers, supported by the EU-funded Graphene Flagship, sprayed solutions of graphene and carbon nanotubes (CNTs) around the enclosures in which the spiders were kept.
The team set out their research recently in a letter titled “Spider silk reinforced by graphene or carbon nanotubes,” published in the online journal 2D Materials. The solutions were ingested by the spiders and when the silk was then harvested it was found that the graphene and nanotubes had made their way into the silk. The team observed an increment of the mechanical properties with respect to pristine silk, up to a fracture strength ~5.4 GPa and a toughness measurement of ~1570 J g−1.
The research was led by Professor Nicola Pugno from Italy's University of Trento who compared the strength shown by the enhanced silk as being comparable to limpet teeth or the strongest carbon fibers. “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 fibers, thus further improving one of the most promising strong materials.”
Not only hugely strong, the fibers are biodegradable opening up new applications for textiles such as medical dressings.
A variety of projects helped to support the research: REPLICA2 (Large-area replication of biological anti-adhesive nanosurfaces), KNOTOUGH (Super-tough knotted fibers), and BIHSNAM (Bio-inspired Hierarchical Super Nanomaterials) all contributed. Graphene is an area of great interest and innovation and the EU’s Graphene Flagship is a key resource for furthering advances in this new domain.
Andrea Ferrari, director of the Cambridge Graphene Centre, Science and Technology Officer of the Graphene Flagship, and Chair of the Flagship's management panel, told Science Daily, “The interaction between graphene and related materials and bio-materials is key to broadening their possible applications. This is one of many examples showing potential in this area. This work can help us to design novel composites with enhanced properties, taking inspiration from nature.”