Spider silk emerging as highly wearable fibre of the future

Turning spider silk into wearable material has long been a quandary for the textile industry. A California company has used biotechnology to come up with a limited-edition woven tie made of genetically engineered spider silk.

The silk woven by spiders is known for its toughness, elasticity and lightweight quality. It can be stronger than steel and can stretch up to five times its length. A strand as long as the circumference of the Earth would weigh a mere pound.

The material bearing such qualities is difficult to obtain in quantity. It is true that a person can wreck a spider web with the flick of a hand. A strand of that web, however, is just three-thousandths of a millimetre in diameter, scaled up to a full millimetre that strand could trap a helicopter like the proverbial fly in the spider’s web.

That silken web has been woven by spiders for 384 million years. Evidence of the activity comes in the form of a Devonian shale containing a spider’s fossilized rear end. It was discovered in New York State and documented in Paul Hillyard’s The Private Life of Spiders. Arachnids have evolved since then into having seven different silken glands. From such glands are produced aciniform silks, silken tubuliform egg sacs, sticky silk globules, dragline silks and other variations of silk.

Throughout history, efforts have been made to exploit the arachnids’ wondrous product. The Ancient Greeks used those egg sacs to bandage wounds. New Guinea fishermen utilised webs of orb spiders to create nets. The very first pair of silvery stockings made from the arachnids’ silk appeared in 1709 in the Court of the Sun King, Louis XIV.

The Civil War surgeon Burt Green Wilder, who first used the term “neuron” in print, devised a basic silken machine. It was just a hinged wooden board trapping the spider’s head and legs on one side, and its abdomen on another. A reel drew the silk from the arachnid. In 1982, researchers at North Carolina State University published a paper on making a device that could force multiple spiders to produce silk in bulk.

Recently, study on programming function into mechanical forms by directed assembly of silk bulk materials was published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

In the 90s, genetics made it possible to produce the silk from modified bacteria, yeast, tobacco plants and even goats. The biotech company that made initial attempts to make silk from other sources, however, went bankrupt.

Bolt Threads went through about four thousand formulations, tinkering with gene sequences using brewer’s yeast. CEO Dan Widmaier related the process of purifying the silk protein into powder, mixing it with solvent and coming up with a goop called “spin dope," which is extruded through a die to create the fibre.

Not yet as strong as steel, or super elastic, or even waterproof, the woven tie is just the start of other things to come. In time, that biosilk can very well make up a sweater or even military armour.