Leggi in italiano

Garden spider spinning a web in Hawaii, USA. Credit: Scott Chernis/Alamy Stock Photo.

Spider silk is the toughest fibre found in nature. When stretched or pulled, it can absorb more energy than steel or nylon without rupturing, and can be used to make bulletproof vests. It is also biocompatible and can be used in the production of surgical thread and artificial ligaments.

But, producing spider silk is a challenge, because spiders cannot be easily bred. Making artificial versions has proven even more difficult, with no attempts so far proving comparable to the real thing. Now an international research team, including Nicola Maria Pugno and Gabriele Greco, from the University of Trento has produced the first artificial fibres whose toughness is similar to those made by spiders1.

Scientists have already modified bacteria or insect cells to have them produce the main proteins of spider silk, called spidroins. But to obtain fibres that can be used in medical applications, it is crucial to control of the solubility and assembly of those proteins. The authors designed various modified spidroins so that they would form stronger bonds. They then genetically engineered Escherichia coli bacteria to produce these modified versions, and finally used spectroscopy techniques to investigate the link between mechanical properties and the modified fibre structure. “The functions and structure of the proteins are partially determined by the chain sequence of their amino acids, and our question was whether it was possible to alter this molecular chain and produce fibres with different or better mechanical properties,” explains Pugno.

The collaboration was led by Anna Rising, a pioneer of the study of fibre silk at the Karolinska Institute in Stockholm, whose pivotal ideas in the field were praised by Greco.

The engineered spidroins resulted in fibres with increased tensile strength, and two fibre types displayed toughness equal to native silk. “We produced a silk three times tougher than Kevlar,“ says Greco. Pugno says he hopes their work will foster new studies on the links between amino acid chain alteration and silk properties. “Maybe in the future we will design spider silk proteins in the same way we design bridges, by searching for specific functions and adjusting protein structure” he says.