Although cobwebs may seem very fragile when we see people like Indiana Jones crashing through them, the fact is that spider silk is an incredibly strong and flexible material. It has a tensile strength similar to that of high-grade steel while only being one-fifth as dense, it can stretch up to 1.4 times its relaxed length without breaking, and it can maintain those properties down to a temperature of -40C (-40F). Given that spiders don't secrete huge quantities of the stuff on a daily basis, however, what's a biotech firm to do if it wishes to harvest the fibers for use in human technology? In the case of Sigma Life Science, it's getting genetically-modified silkworms to spin spider silk.
Sigma has partnered with Kraig Biocraft Laboratories (KBLB) to develop the silkworms, using Sigma's proprietary CompoZr Zinc Finger Nuclease (ZFN) technology.
Last year, KBLB successfully created hybrid silkworms with randomly inserted spider genes. The creatures secreted hybrid "spidersilkworm" silk, that was stronger and more durable than silk from regular silkworms, but still not as strong as spider silk.
Utilizing the claimed precise gene targeting and high efficiency of the ZFN process, KBLB and Sigma now plan on inserting spider silk genes into the silkworm genome, while simultaneously removing the native silkworm silk genes. The result, the companies hope, will be transgenic silkworms that produce pure spider silk "at commercially viable production levels."
The material may be used in applications such as sutures, tendon and ligament repair, bulletproof vests, and automobile airbags.