Lab Spins Artificial Spider Silk, Paving the Way to New Materials

January 17, 2002

Tougher than Kevlar and stronger than steel, spider silk has long intrigued engineers and scientists because of its potential industrial and medical applications.

Now, a biotech company in Canada has developed a method for producing artificial spider silk by inserting the genes for spider silk into the cells of mammals.

In experiments so far the researchers have produced spider silk by inserting the gene into the genome of cows and hamsters. The company plans to also insert the silk-producing gene into goats with the aim of collecting silk proteins from goat milk.

The scientists at Nexia Biotechnology in Quebec reported their new method of creating a type of spider silk, known as "dragline," in the January 18 issue of the journal Science.

Orb-weaving spiders generally produce about seven different types of silk, which they use for different purposes. Scientists are most interested in dragline silk, from which a spider constructs the outermost circle of a web and all the spokes radiating from the center.

"Dragline silk is also the silk spiders spin as they fall from the ceiling—it's their lifeline," said Randolph Lewis of the University of Wyoming in Laramie.

Many Potential Applications

The strength and elasticity of spider silk make it a good candidate for a broad range of medical and industrial applications, including artificial tendons and ligaments, sutures for ophthalmic and micro surgery, biodegradable fishing line, bulletproof vests and lightweight body armor, parachute cords (particularly when dropping tanks or other heavy objects), and cables used to help stop planes as they land on aircraft carriers.

Yet until now, manufacturing silk fiber has been surprisingly difficult.

Natural dragline silk is made up of two proteins. They were identified a decade ago by Lewis and his colleagues, but attempts to use the two genes that encode these proteins to mass-produce spider silk were unsuccessful.

According to researchers, one reason silk is so difficult to make if you're not a spider is because the proteins are so large. Bacterial cells are often used to make artificial proteins in the lab. In this case, however, the spider silk proteins are too large and the cells cannot make and release large quantities. So the researcher tried using mammal cells instead.

Manufacturing large proteins is a challenge for any cell. To overcome that obstacle, the Canadian scientists used a shortened version of one of the two genes for dragline silk (called ADF-3) and inserted it into hamster and bovine cells, which are capable of manufacturing and releasing high quantities of a protein.

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