Spider silk research could lead to new super-materials
Making bricks from straw may soon be possible and even desirable after scientists found spider silk could make ordinary materials stronger than steal.
Researchers found that spider silk employs a unique crystal structure that converts an otherwise weak material into one stronger and less brittle than steel or ceramics.
They believe in future it may be possible to copy spider ingenuity to create new classes of materials that are both incredibly flexible and strong out of cheap, ordinary elements.
Theoretically, they could even be made from wood, straw or hemp, say the scientists.
Carbon-based materials made the same way would be even stronger than spider silk.
A key property of spider silk is its combination of strength and "ductility" – its ability to bend or stretch without breaking.
Most man-made materials, in contrast, sacrifice strength for ductility. Ceramics, for instance, are strong yet brittle.
Scientists at the Massachusetts Institute of Technology (MIT) in Cambridge, US, studied the fundamental properties of spider silk using computer models to simulate its structure.
The silk is made from proteins including some that form thin flat crystals called beta-sheets.
The researchers found that the size of the crystals was critical.
When they measured about three nanometres (three millionths of a millimetre) across they made the silk ultra-strong and ductile.
But if the crystals grew to five nanometres the material became weak and brittle.
Spider silk was strong despite its components being connected by naturally weak hydrogen chemical bonds, said the scientists.
The geometry of the crystals allowed the hydrogen bonds to work co-operatively, shielding each other against external forces.
The researchers, led by Professor Markus Buehler from MIT's Department of Civil and Environmental Engineering, wrote in the journal Nature Materials: "The application of our findings to the design of synthetic materials could provide us with new material concepts based on inexpensive, abundant constituents."