Metal Doping Makes For Super Spider Silk

Silk is a high-performance fiber in its own right, but adding a dash of metal to the biomaterial takes its strength and stretchiness to the next level, according to a report in Science (2009, 324, 488). Such souped-up silk might someday find its way into surgical thread or artificial tendons. Inspired by inorganic impurities that lend toughness to proteins in animal stingers and claws, Seung-Mo Lee and Mato Knez of the Max Planck Institute of Microstructure Physics, in Halle, Germany, and coworkers developed a metal-doping technique intended for strengthening other types of biomaterials. The team used atomic-layer deposition to incorporate zinc, titanium, or aluminum into spider silk. The metal-infused silk is much more resistant to breaking than normal silk, the researchers found. Although the metals' role in the superstrong silk isn't yet clear, evidence from NMR and X-ray measurements suggests that the metal ions coordinate to the silk protein and perhaps form covalent bonds.