An international scientific team in which UPM researchers are involved has developed a bioinspired method that for the first time will allow researchers to spin artificial silk fibers as spiders do and to efficiently produce kilometers of silk.
Researchers from the Centre for Biomedical Technology at Universidad Politécnica de Madrid were involved in this research project that was recently published in the journal Nature Chemical Biology. The results of the study show the first procedure to produce artificial spider silk by imitating the natural procedure of spiders. This imitation was obtained by developing recombinant proteins with the same water solubility that the natural silk and a spinning system based on, as it is occurs in the spider glands, aqueous solutions, stress generated during the spinning and pH reduction.
The production of fibers that equal or improve the excellent properties of spider silk is a breakthrough, since other previous works only used aqueous solutions. Researchers shown that is possible to produce kilometers of fibers with mechanical properties that are similar to the spider silk. This material has great applications in the field of tissue engineering and regenerative medicine, among others.
Silks are materials with great biocompatibility and excellent mechanical properties due to their great strength and deformability. However, not all silks are the same. Compared to the silk obtain from worms (Bombyx mori species), the silk produce by spiders has better mechanical properties and is considered the natural fiber with the highest mechanical features.
These characteristics make spider silk an excellent candidate as biomaterials in tissue engineering. However, unlike what happens in the case of worm silks, spider silk had not been produced at industrial scale before since spiders are solitary and predatory animals what makes it difficult their grow in captivity.
Spider silk is made up of proteins (spidroins) that before the spinning, they remain stored as an aqueous solution in specific glands of the animal. Previous studies carried out by members of the research team from Swedish University of Agricultural Sciences and Karolinska Institutet suggest that there is a significant pH gradient in the silk glands.
The gradient regulation affects specific parts of the spider silk proteins and as a result, the fiber is rapidly formed at a particular location in the production apparatus. This help design an artificial spider silk protein that includes amino acid sequences of the spidroins of two different species. This chimeric protein has been shown to be as water soluble as the natural spider silk proteins, this allows researchers to produce large quantities of silk using bacteria. Thus, the production of artificial spider silk is scalable, and consequently interesting for the industry.
In order to mimic the natural process that occurs in the silk gland of spiders, the research team, led by Professor Anna Rising, has built an efficient biomimetic spinning process in which, by reducing the pH and with the help of the stress appearing in the fiber spinning duct, can obtain kilometric fibers from the aqueous protein solution.
According to the researchers, "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."