Pin It

Silkworms are the larvae of the silk moth, one of thousands of insect species that wrap themselves in cocoons as they prepare for metamorphosis. It’s one of nature’s most industrious insects — and the only one that has ever been domesticated.

The Chinese perfected the art of harvesting the single, half-mile long thread that forms each cocoon, transforming worm silk into a luxurious fabric at least 5,000 years ago. Dr. Randy Lewis of Utah State University’s department of biological engineering is looking to improve on the ancient practice — as are many of his competitors in the emerging field of high performance biomaterials.

Silkworm silk makes wonderful scarves and undergarments, but biologists have long had their eyes on spider silk. The webs of some arachnid species have the tensile strength of steel, while remaining completely elastic. “The difficulty is that spiders are territorial and cannibalistic,” says Lewis. “Unlike silkworms, you can’t just put them all together and expect them to have a nice, happy tea set.” In short, spiders have resisted all efforts at domestication — not to mention, who would want to farm spiders? And bushwhacking through the jungle to harvest the best wild spider webs isn’t cost effective.

For a genetic engineer daydreaming of spider silk produced in a commercially viable way, it doesn’t take long to connect the dots to the docile, communal silkworm. In parts of India, China and much of Southeast Asia, they are traditionally reared by the thousands in small wooden crates in the huts of rural peasants. The farmer must also grow mulberry trees, the leaves of which are the only thing a silkworm will eat. While the methods for spinning silk threads into fabric has become wrapped into the fold of the global textiles industry, the practice of raising the worms and unwinding each cocoon by hand has been surprisingly untouched by the tentacles of modernization.

Not so with silkworms and their genes, however. Feeding silkworms artificial colorants has produced ‘pre-dyed’ silk threads that preclude the need for the costly and toxic silk dyeing process (apparently with no harm done to the worms). Researchers in Japan have engineered silkworms to spin glow-in-the dark thread for use in high-end fashion design in hopes of building a niche silk market that will put a dent in China’s global dominance of the silk trade.

But the holy grail of silkworm gene splicing is to make the little larva pump out spider silk, a substance that can be woven into products that make Kevlar look flimsy. Interested parties have been salivating for years over the potential applications, which go far beyond fabrics: The U.S. Navy wants spider silk for its ability to adhere to any material, even underwater; the Department of Energy is hoping to make vehicles lighter and thus more fuel efficient by integrating silk proteins into the manufacture of door panels; and the Air Force is envisioning lightweight, bulletproof body armor that is easier to maneuver in during combat. The medical applications are all over the map: artificial skin for burn patients, better Band-Aids, synthetic ligaments, micro-sutures for delicate organs like the eyes and host of surgical implants and drug delivery.

To read more, click here.