Artificial "Spiber" silk is tougher than Kevlar
July 12, 2013
Spider silk is a truly remarkable material: it's tougher than Kevlar, strong as steel, lighter than carbon fiber, and can be stretched 40 percent beyond its original length without breaking. Now, Japanese startup Spiber says it has found a way to produce it synthetically and, over the next two years, will step up mass production to create anything from surgical materials to auto parts and bulletproof vests.
Artificial silk could be used to create artificial blood vessels and ligaments, as well as dissolvable sutures (for centuries, silk was used to dress wounds for its antibacterial properties). In the auto industry it could lead to bumpers that can absorb a very large amount of energy on the impact, improving driver safety.
Spider silk owes its amazing properties to a protein named fibroin. Proteins are the catalyst for most chemical reactions inside a cell and help bind cells together into tissues. They are long chains of about 20 different types of aminoacids, which can combine into a nearly infinite number of configurations.
The complex sequence of aminoacids that make up fibroin is proving tough to recreate in a lab. A "spider farm" wouldn't produce nearly enough silk for industrial use, so companies around the world are turning to genetic engineering instead. Some companies modified goats to produce milk containing spider silk; others used silkworms to the same end; and others yet are using genetically modified bacteria.
Spin me a web
Spiber's approach is the latter. The company's process involves decoding the gene responsible for the production of fibroin in spiders and then bioengineering bacteria with recombinant DNA to produce the protein, which they then spin into their artificial silk.
While interest in artificial silk is high and competition is tough, Spiber says it has the advantage of speed: apparently, it can engineer a new type of silk in as little as 10 days, and has already created 250 prototypes with characteristics to suit specific applications.
Spyber starts by tweaking the aminoacid sequences and gene arrangements in its computer models to create artificial proteins that try to maximize strength, flexibility and thermal stability in the final product.
Then, the company synthesizes a fibroin-producing gene, modifying it in such a way that it will produce that specific molecule. The company adopts its own system of gene synthesis, which can produce large quantities of DNA for the fibroin gene in only three days.
Microbes are then modified with the fibroin gene to produce the candidate molecule, which is turned into a fine powder and then spun. The bacteria feed on sugar, salt and other micronutrients and can reproduce in just 20 minutes. A single gram of the protein produces about 5.6 miles (9 km) of artificial silk.
The artificial protein derived from fibroin has been named QMONOS, from the Japanese word for spider. The substance can be turned into fiber, film, gel, sponge, powder, and nanofiber form to suit a number of different needs.
Spibers says it is building a trial manufacturing research plant, aiming to produce 100 kg (220 lb) of QMONOS fiber per month by November. The pilot plant will be ready by 2015, by which time the company aims to produce 10 metric tons (22,000 lb) of silk per year.
The video below introduces the attractive features of the silk and some of its possible applications.