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Companies Genetically Engineer Spider Silk
gthuang88 writes: Spider silk is touted for its strength and potential to be used in body armor, sports gear, and even artificial tendons and implants. Now several companies including EntoGenetics, Kraig Labs, and Araknitek have developed genetic approaches to producing commercial quantities of the stuff. One method is to implant spider genes into silkworms, which then act as spider-silk factories. Another is to place the gene that encodes spider web production into the DNA of goats; these "spidergoats" then produce milk containing spider-silk proteins that can be extracted. There's still a long way to go, however, and big companies like DuPont and BASF have tried and failed to commercialize similar materials.
I actually invested money into the now dissolved Canadian company, Nexia Biotechnologies, which was the first to do the spider-goats. You are entirely correctly. Spinning the silk is the harder second part. The gains in reducing cost per meter couldn't keep the pace with similar gains in carbon nanotubes, which competed for many of the same practical applications. Nexia's first path to market was to be superstrong medical sutures. At first, the FDA promised expensive human trials would not be needed since the proteins were naturally occurring. When the FDA later about-faced, it was Game Over for Nexia, who sold the IP rights to a company in Virginia. They also sold the IP behind their proven anti-chemical warfare agents. But the tyrants of the world never used chemical warfare against the US military, so that was (thankfully) also a financial bust.
Nexia was also trying to GMO a plant crop that could grow the silk protein in their leaves. After harvesting, the leaves would be grinded and sifted. However, you're still back to the same Spinning Problem that you highlighted.
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Just read the article myself;
This is still about the protein itself, not the mechanical processing done by the spider to create the unique fibers they produce.
Basically, the spider's silk protein is a bit like a "hook and latch", much like a zipper's teeth. Mass producing the protein produces "Zipper teeth", but that does not result in the unique conformation of a zipped up zipper.
For that, you need the zipper pull.
That's what a spider's spinnarets do. As the liquid crystal solution of spider protein gets pulled into the spinnaret, it gets compressed mechanically in a special fashion, which causes spontaneous self-assembly of these "zipper teeth", into a fully assembled, fully interlocking "zipper" of interlocked protein molecules. It is this fully interlocked assemblage that gives spider silk its unique mechanical properties.
The shape and length of these structures in the spider's abdomen are crucial to correct assembly.
As the linked Nature paper I linked to points out, this process is NOT incorporated in any currently used textile processing system.
Getting bulk, high quality protein is only PART of getting mass produced spider silk. The other part is the mechanical processing.
Silkworms do not have the structures that spiders do for processing their silk. Instead, silkworms produce a kind of salivary secretion through a much larger orifice. This orifice is much larger than a spider's spinnaret, and is not the same shape. This is why silk worms producing spider proteins will not produce silk of the same quality.
Now, we have some pretty kick ass micro-pipette technology these days (and surface morphology control on silicon substrates from PV solar research) that could probably be used to create synthetic spinnarettes--- Just wet one side with the silk solution, then draw silk fibers from the other side.
I just have never heard of any serious research into creating such synthetic spinnaret technologies.