The Race to Make Spider Silk

The strength, toughness, and elasticity of silk continue to fascinate scientists, who wonder what gives this natural material its unusual qualities. Finer than human hair, lighter than cotton, and ounce for ounce stronger than steel, silk is of special interest to materials researchers. They are trying to duplicate its properties and synthesise it for large-scale production. Silk holds the promise of wear-resistant shoes and clothes; stronger ropes, nets, seatbelts and parachutes; rustfree panels and bumpers for automobiles; improved sutures and bandages; artificial tendons and ligaments; supports for weakened blood vessels as well as bulletproof vests. Many insects secrete silks of varying quality. Best known is the moth bombyx mori, whose caterpillar is commonly known as the silkworm. It spins its cocoon from a single thread between 300 and 900 metres long and has been used for centuries to make fine garments. But the focus of scientific attention today is on spider silk: tougher, stretchier, and more waterproof than silkworm strands. Spiders make as many as seven different types of silk, but one spider and two types of silk are at the centre of intense interest. The spider is the golden orb-weaving spider, nephila clavipes. Its two silks under investigation go by the evocative names ‘dragline’ and ‘capture’. Dragline is the silk which forms the frame for the wheel-shaped webs and enables the dangling spider to drop down and grab its prey. This silk exhibits a combination of strength and toughness unmatched by high-performance synthetic fibre. Capture silk is the…