Secrets of spider silk revealed

Spiders are in many ways remarkable creatures, but it is perhaps the silk they spin for their webs that is their most fascinating aspect.

Weight for weight, spider silk is about six times stronger than steel. In theory, spider silk as thick as a pencil would be able to catch a jumbo jet or tow an ocean-going liner.

Spider silk consists of protein molecules arranged in long chains of thousands of amino acid elements. The chains contain areas linked together with stable connections, providing great stability, alternating with unlinked sections that give the silk its elasticity.

A body of folklore surrounds the wound-healing capabilities of spider webs. They were successfully used to bind wounds in a manner similar to gauze. However, the webs caused problems if contaminated with pathogens, including tetanus, and babies frequently died after having their umbilicus dressed with spider webs.

Recent research carried out at the University of Bayreuth in Germany has revealed the exact mechanism by which spiders can spin their silk at a moment’s notice from a reservoir of liquid silk protein. The goal of most research into spider silk is to produce the silk artificially in commercially viable quantities.

Products have been developed that are modelled on spider silk proteins, and a team at the University of Wyoming, led by Randy Lewis, has successfully implanted the silk-making genes from the golden orb spider into a herd of goats, allowing silk protein to be recovered from the goats’ milk.

Spider silk is similar in composition to human structural proteins. If it could be used as a scaffold for cartilage or bone repair, it should be a material that human cells could adhere to and grow upon, since it initiates no inflammatory reaction in the host cells. An added advantage is that the silk is broken down into its constituent amino acids, which would lend it to application as a suture material.

However, before scientists get carried away with the possibility of all these applications, the last word must go to Professor Lewis, who commented: “If it works, the first application, to be frank, could be in the manufacture of fishing line.”