How do spider silks become fibers? The development and application of spider silk protein.

The fanfare about spider silk has been going on since the 18th century.
At the time, in a letter to colleagues, Fran?ois Xavier Bon de Saint Hilaire, president of the Royal Society of Science in Montpellier, wrote: "You will be very surprised to hear that the silk produced by spiders is as beautiful, strong and smooth as ordinary silk.
" modern touting claims that spider silk is five times more powerful than steel, but still more flexible than rubber.
if it could be made into a rope, a large-scale net would be able to hold a jetliner.
keyword is "if".
researchers first cloned the spider silk gene in 1990 in the hope of implanting it into other organisms to produce the silk.
spiders cannot be bred like silkworms because they are site-based and eat in the same way. How do
spider silk make a fiber? Today, E. coli, yeasts, plants, silkworms and even goats can be genetically modified to produce large amounts of spider silk protein, although these proteins are usually shorter and simpler than the spiders' own proteins.
has succeeded in moving the protein into a line that is strong enough to produce a number of clothing prototypes, including Adidas' running shoes and North Face's light coat.
, however, the company is still working on mass production of such garments.
managers say they may eventually change their strategy.
Threads, a start-up based in Emoliville, California, says it has perfected its approach to growing spider silk protein in yeast and is expected to produce tons of spider silk each year.
, In Lansing, Michigan, Kraig Biocraft Labs says it can produce a large amount of spider silk and silk mixtures only through final negotiations with vietnamese silk farms.
, the U.S. military is testing it for ballistics protection.
", has made great progress in this area since the 1990s.
then, large-scale production of spider silk seemed out of reach, both on a functional scale and on a commercial scale.
," says My Hedhammar, a biochemist at the Royal Swedish Institute of Technology.
However, many biotech and research observers are wary of the prospect of mass production of spider wire ropes and fibers. "At this point, this area has not yet progressed,"
. "We still can't see these things on store shelves," said Cheryl Hayashi, a spider geneticist at the American Museum of Natural History,
.
"People's dream is to imitate the strongest of the seven kinds of silk that spiders spit out: the tow sands that can hang spiders online and contain seven kinds of spider protein."
these protein molecules are large -- each with a maximum of 600 kDa, almost twice the size of a normal human protein.
makes it difficult to produce in genetically modified organisms.
companies mostly choose to produce versions of 50 to 200 kDa because they are easier to express.
silk produced by these smaller proteins is usually less strong and flexible.
" In some ways, as the protein becomes smaller, mechanical properties are lost.
," said Randy Lewis, a chemist at Utah State University.
Lewis team was the first to clone the spider silk gene.
development and application of spider silk protein, studies have shown that it is difficult to mimic the way spiders spin concentrated protein into fiber.
currently, Lewis is able to spin spider silk protein into water-insoluble fibers and eliminate the need for expensive and potentially toxic organic solvents.
team led by The Royal Swedish Institute of Technology fluid physicist Daniel S?derberg found a way to form fibers using linearcellfibers in wood and paper to form fibers.
however, it is another matter to spin these filaments into fibers on a commercial scale.
" is a huge challenge.
", says Lin R?mer, chief technology officer of AMSilk, a Spider Silk start-up based in Munich, Germany.
spider silk protein has entered the market, but only in cosmetics and medical devices, not in high-strength fibers.
AMSilk grows spider silk protein in E. coli and drys the purified protein to form powder, or mixes it into a gel for use as an additive in personal care products such as moisturizing lotions.
, spider silk protein is said to help the emulsion form a very smooth, breathable protective layer on the skin.
sell tons of purified spider silk protein each year, according to Mr. R?mer.
AMSilk is also completing a clinical trial of a silicone breast implant encased in the company's spider silk protein.
these proteins contain highly repetitive sequences of small amino acids, they are said to be almost impossible for the immune system to detect.
package is also easier to get rid of bacteria than Teflon or stainless steel. These advantages should allow the company to use spider silk wraps to improve many implants, from artificial hips to catheters, according to
R?mer.
Kraig Biocraft Labs and Stockholm-based Spiber Technologies say they are also developing similar applications.
.