Spider silk is 10 times stronger than Kevlar

Protein discovery has implications for biomechanics and manufacturing.

Spider silk is extremely tough and flexible, but Madagascar’s Darwin’s bark spider (Caerostris darwini) takes this to another level. Its dragline silk is twice as strong as any other thus far tested, and an astonishing 10 times stronger than the synthetic fibre Kevlar.

This property was long ago noticed by researchers in the field of biomechanical design, but the exact biological processes that result in the super-strong fibre remained a mystery. Now, scientists led by Jessica Garb from the University of Massachusetts Lowell in the US might have found the answer.

In a paper published in the journal Communications Biology, they report that the silk is the result of “a suite of novel traits from the level of genes to spinning physiology to silk biomechanics”.

All orb spiders produce silk containing two distinct sets of repetitive proteins. The number of repeats, and the ratio between the two types, govern the properties of the various types of silk each spider produces.

The dragline silk of Darwin’s bark spider, Garb and colleagues discovered, contains a third protein that lacks some of the components of the other two, but is unusually rich in a type of amino acid called proline, which is associated with elasticity. This, they suggest, “may in part explain the greater extensibility and toughness” of the fibre. And it will create a great deal of interest.

“We anticipate these findings will be leveraged to produce silk-based materials mimicking the extraordinary toughness of C. darwini dragline,” they conclude.