Scientists have produced the first “recombinant” spider silk that mimics the toughness of the natural material. Recombinant refers to the process of creating DNA molecules, formed by laboratory methods of genetic recombination (such as molecular cloning). This is in order to bring together genetic material from multiple sources (in this case from bacteria and spiders.) The end result is a “recombinant organism.” This means any organism that contains a different combination of genes from its parents (if it were an animal), or previous generations, in the case of bacteria.
With the study, according to New Scientist, researchers based at the University of Bayreuth in Germany expressed variants of one of three spider silk proteins from the European garden spider (Araneus diadematus) in the bacterium Escherichia coli. Previous studies only used versions of the protein containing the two central domains, which create a tough crystal-like structure nestled inside a stretchy gel-like material. However, in a breakthrough, the Bayreuth researchers included two domains that naturally occur at the ends of the protein. With the new breakthrough, key to the success was by including domains of the silk protein that help silk strands form properly.
Once the bacteria produced the protein, the scientists allowed the silk to self-assemble in a bath of water and alcohol before stretching the fibers to six times their original length. This process is called “wet spinning” and was designed to mimic a spider drawing the silk out of its body with its hind legs. This technique improves the alignment of the proteins and the fiber’s toughness.
The scientists discovered that the recombinant fibers were more elastic but weaker than real silk. However, because toughness is a combination of elasticity and strength, the artificial fibers were deemed as tough as the natural product.
Importantly, if the process can be scaled up then it could be used for creating airbags, used in cars as a safety feature, with higher elasticity.
The research has been published in the journal Advanced Materials. The research paper is called “Biomimetic Fibers Made of Recombinant Spidroins with the Same Toughness as Natural Spider Silk.”
In related news, Digital Journal reported in 2014 that scientists had genetically engineered silk worms to manufacture a tough, strong and durable form of silk.
