Tuesday, 20 March 2012

Silkworm Spider Silk Hybrid

Silkworm Spider Silk Hybrid

Spider silk is a really strong material and can absorb lots of energy; so if harnessed and made correctly, could be turned into something such as body armour; it would be perfect for absorbing the force of bullets and shrapnel.
The problem is that it’s not easy to farm spiders because they usually attack and kill each other. So basically there needs to be a better way to successfully harness a decent amount of spider silk.

Spider silk info: Silk is made in the abdomen of the spider and then made into strong strands. Silk has a very complex structure but is mainly made of protein. The amino acid sequence is mostly made up of glycine and alanine blocks. The alanine side chains are formed in a semi crystalline structure. Pyrrolidine, which attracts water, is added to keep the silk moist. Other molecules that are found in the silk structure are; sugars, lipids, ions and pigments. They add extra strength to the silk and help protect the outside of it.

 Some toughness facts: At the same weight, spider silk is five times stronger than steel. It can stretch sometimes four times its normal length. Also it has a pH of 4 making it acidic; this prevents bacteria and fungi from consuming it. As you can see it is a very complex structure, made from many different compounds. The structure is actually still not entirely understood. This is why it has not been made synthetically.

So far there have been a few attempts to produce decent amounts of spider silk without farming spiders. The main problems are; finding the genome details of the best silk (spiders make different kinds of silk for different things). Harnessing the protein which makes silk, then figure out a way to make large quantities of it.
Producing silk protein has been successful. The problem with is that once the silk proteins were made it has been hard to make into the correct fibres arrangement that the spider spins. Scientists have grown the silk protein in tomato and tobacco seeds and even using e.coli.

But the idea came up of using silkworms to farm spider silk. Regular silkworm silk is already used in some cultures but it is nowhere near as strong as spider silk. The process of trying to use silkworms for spider silk has been tried a few times but with failed attempts. But, recently the University of Wyoming announced that they had done it. They took the genetic sequencing of spider silk proteins and were able to add it to the silkworms. This created a mixture of spider and silkworm silk, not quite as strong as spider silk but pretty close. The genetic process used is called PiggyBac. In short it is a process of basically cutting and pasting bits of DNA into other cells.
This is great news, this hybrid spider silk could be used not only for body armour but also used to make special clothing, dressings for wounds and even artificial tendons and ligaments. An exciting new industry of spider silk may soon emerge in the coming years.

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