Spider silk has a myriad of potential uses, if only spiders could be convinced to produce vast quantities on demand and work long shifts. Unfortunately, the difficulty in keeping spiders and the small quantities of silk they are able to produce means natural spider silk is unlikely to have many commercial applications. However, if scientists could develop an artificial silk that has the same properties as spider silk, and be able to generate large volumes of the material, the potential applications are considerable.
Spider silk has some rather amazing properties. First of all is its strength. Weight for weight spider silk is stronger than steel. Secondly, the material is incredibly lightweight and more durable and elastic than any man-made fiber. If enough of the silk could be produced to encircle the globe, the thread would weigh less than a bar of soap. Spider silk can also stretch up to 140 percent of its length without snapping. The strength, durability and elasticity of the material makes it perfect for a host of advanced textiles. Spider silk is also biodegradable and well tolerated when implanted in biological tissues. The material could therefore be used in surgery.
Researchers have long tried to replicate spider silk, but rather than use spiders they have developed artificial silk proteins or have attempted to obtain similar proteins from bacteria. However, all have experienced problems obtaining water-soluble proteins, developing artificial spinning processes, or both.
Now, a team of researchers from the Swedish University of Agricultural Sciences have made something of a breakthrough. They have managed to produce artificial spider silk and have used the process to generate silk strings one kilometer long. Bacteria were used to produce the proteins, which are as water-soluble as spider silk proteins. Furthermore, the method of production and spinning is highly scalable, opening the door to a wide range of commercial applications.
The researchers developed a biomimetic spinning process mimicking the way spiders spin silk. Before silk emerges from spiders’ spinnerets and solidifies, it is an aqueous solution. As the liquid passes through ducts, water is extracted and hydrogen is pumped in creating a form of acid bath which turns from liquid to solid. The pH gradient is precisely controlled to ensure that the silk doesn’t start to harden in the wrong place blocking up the ducts. That process has been copied by Anna Rising and her colleagues at the Swedish University of Agricultural Sciences.
Rising says, “This is the first successful example of biomimetic spider silk spinning. We have designed a process that recapitulates many of the complex molecular mechanisms of native silk spinning. In the future, this may allow industrial production of artificial spider silk for biomaterial applications or for the manufacture of advanced textiles.”