Spiders' silk constructions have fascinated researchers for years, yet many of the structural and mechanical properties of spider silk remain elusive. One strange mechanical property of spider silk, in particular, puzzles silk researchers: when submerged in water, silk fibres supercontract to half their original length. But it was unclear if supercontraction happened at any point during the natural spinning process. Manuel Elices' team decided to investigate the biological significance of supercontraction().
The team reasoned that if they could show that the tensile properties of man-made supercontracted silk were identical to those of naturally spun silk,this would indicate that supercontraction plays a significant role during natural silk spinning. But for biologically meaningful results, the team had to ensure that the man-made supercontracted fibres were subjected to the same influences that natural silk fibres would experience in the spiders' silk gland. Using a simple but innovative approach to create the man-made supercontracted fibres, they submerged silk in water until it was completely supercontracted, stretched the silk to a particular length under water and then dried the fibres. When the team tested the stress-strain characteristics of these fibres, they found that they could mimic the entire range of tensile properties of natural silk fibres. Elices' team concludes that wet-stretching and subsequent drying of supercontracted fibres may play an important role in spider web-building.
