Scientists unravel the mysteries of spider silk

Scientists at Arizona State University (ASU) have found a way to obtain the elastic properties of spider silk using a non-invasive laser light scattering technique.

“Spider silk has a unique combination of mechanical strength and elasticity that make it one of the toughest materials we know,” said ASU’s Professor Jeffery Yarger.

Spider silk is an exceptional biological polymer, related to collagen but much more complex in its structure.

The ASU team of chemists studied its molecular structure in an effort to produce materials ranging from bulletproof vests to artificial tendons.

We can extract the elastic properties of spider silk that cannot and have not been measured with conventional testing

The team used the Brillouin light scattering technique which uses an extremely low power laser of less than 3.5 milliwatts.

Recording what happened to this laser beam as it passed through the intact spider webs enabled the researchers to spatially map the elastic stiffnesses of each web without deforming or disrupting it.

This non-invasive, non-contact measurement produced findings showing variations among discrete fibers, junctions and glue spots.

The group also investigated one of the most studied aspects of orb-weaving dragline spider silk, namely super contraction, a property unique to silk.

Spider silk takes up water when exposed to high humidity. Absorbed water leads to shrinkage in an unrestrained fiber up to 50 per cent shrinkage.

Their results were consistent with the hypothesis that super contraction helps the spider tailor the properties of the silk during spinning.

The array of elastic and mechanical properties of spider silks in situ obtained by team is the first of its kind, according to ASU.

The research is expected to facilitate future modelling efforts aimed at understanding the interplay of the mechanical properties and the molecular structure of silk used to produce spider webs.

“This study is unique in that we can extract all the elastic properties of spider silk that cannot and have not been measured with conventional testing,” said Yarger.