July 19, 2012
Spider Silk May One Day Be Produced From Bacteria
Brett Smith for redOrbit.com - Your Universe Online
In a development that could have wide reaching ramification for material production, researchers may have finally unlocked a consistent process for producing spider silk from bacteria.
A new video article in JoVE, the Journal of Visualized Experiments, demonstrates a key step in the procedures to harvest and process synthetic spider silk from bacteria called “post-spin.” In this step, silk molecules are mechanically stretched to increase fiber strength.
The automated production improvements, developed by Craig Vierra and a team of researchers from the University of the Pacific, produce uniform spider silk and remove human error from the spinning process. The resulting synthetic silk is remarkably similar to the natural fibers produced by the female black widow spider, and the procedure provides a scalable ground work that could be modified to produce the fiber en masse.
Scientists have been able to produce synthetic silk with the same biochemical makeup of the natural fibers for some time. The first step in silk production is the genesis of feedstock, or un-spun liquid silk compound. The feedstock is then “spun” using one of many techniques, including the use of capillary action or a needle and syringe.
The main stumbling block in synthetic silk production so far has been the ability to consistently replicate a spider's "post-spin" technique. This key step in the process stretches the fiber in order to align the fiber molecules, and thereby increasing the fiber's tensile strength.
To attempt to solve this problem, Vierra and his laboratory group devised a mechanical actuator that can reliably stretch fibers to a desired length, mimicking the spider's natural post-spin.
"The procedure decreases the variance in the mechanical properties that are seen,” Vierra told JoVE. ”Before this procedure, there was a tremendous amount of variation in synthetic fibers."
Spiders produce around six or seven different types of fibers and their silk rivals some of the best manmade and natural materials. It is of particular interest because of the thread´s high tensile strength, which is comparable to Kevlar, but is lighter and less dense.
Practical applications of spider silk date back to early civilization when it was used for fishing and as a wound dressing because of its vitamin K-derived blood-clotting ability. In recent years, silk fibers have been used in mammalian neurosurgery and optical fiber communication.
Since the mass production of natural spider silk is impractical, synthetic silk production has the ability to provide scientists with access to an unlimited supply of the material. Therefore, if scientists could reproduce the mechanical properties of spider silk in the laboratory, the artificial fibers have the potential use for a broad range of applications including body armor, surgical sutures, strings for musical instruments, and composites for aviation and building materials.
"We're working on fusing what we've learned here and expanding the procedure en masse,” Vierra said.
He added that the lab aims to make synthetic silk that is even stronger than the fiber produced naturally by spiders. If Vierra and his team were to be successful, synthetic silk would become a renewable resource for material production that may change future engineering techniques.