ABSTRACT
Spider dragline silk is distinguished through the highest toughness of all natural as well as artificial fiber materials. To unravel the toughness's molecular foundation and to enable manufacturing biomimetic analogues, we investigated the morphological and functional structure of recombinant fibers, which exhibit toughness similar to that of the natural template, on the molecular scale by means of vibrational spectroscopy and on the mesoscale by X-ray scattering. Whereas the former was used to identify protein secondary structures and their alignment in the natural as well as artificial silks, the latter revealed nanometer-sized crystallites on the higher structural level. Furthermore, a spectral red shift of a crystal-specific absorption band demonstrated that macroscopically applied stress is directly transferred to the molecular scale, where it is finally dissipated. Concerning this feature, both the natural as well as the biomimetic fibers are almost indistinguishable, giving rise to the toughness of both fiber materials.
Subject(s)
Silk/chemistry , Spiders/chemistry , Amino Acid Sequence , Animals , Biomimetics/methods , Fibroins/chemistry , Protein Structure, Secondary , Tensile StrengthABSTRACT
Spider silk fibers have a sophisticated hierarchical structure composed of proteins with highly repetitive sequences. Their extraordinary mechanical properties, defined by a unique combination of strength and extensibility, are superior to most man-made fibers. Therefore, spider silk has fascinated mankind for thousands of years. However, due to their aggressive territorial behavior, farming of spiders is not feasible on a large scale. For this reason, biotechnological approaches were recently developed for the production of recombinant spider silk proteins. These recombinant proteins can be assembled into a variety of morphologies with a great range of properties for technical and medical applications. Here, the different approaches of biotechnological production and the advances in material processing toward various applications will be reviewed.
Subject(s)
Biotechnology/methods , Fibroins/biosynthesis , Spiders/metabolism , Animals , Fibroins/chemistry , Fibroins/genetics , Recombinant Proteins/biosynthesisABSTRACT
Natural spider silk fibers combine extraordinary properties such as stability and flexibility which results in a toughness superseding that of all other fiber materials. As the spider's aggressive territorial behavior renders their farming not feasible, the biotechnological production of spider silk proteins (spidroins) is essential in order to investigate and employ them for applications. In order to accomplish this task, two approaches have been tested: firstly, the expression of partial cDNAs, and secondly, the expression of synthetic genes in several host organisms, including bacteria, yeast, plants, insect cells, mammalian cells, and transgenic animals. The experienced problems include genetic instability, limitations of the translational and transcriptional machinery, and low solubility of the produced proteins. Here, an overview of attempts to recombinantly produce spidroins will be given, and advantages and disadvantages of the different approaches and host organisms will be discussed.
Subject(s)
Arthropod Proteins , Silk , Animals , Biotechnology , Fibroins , Proteins , SpidersABSTRACT
Using a self-assembly of recombinant spidroins, biomimetic spinning dopes are produced and wet-spun into fibers. Upon varying the molecular design of the underlying recombinant spidroins, the influence of the amino- and carboxy-terminal domains, as well as the size of the repetitive core domain on fiber mechanics, is determined. Fiber toughness upon biomimetic processing equals and even slightly exceeds that of natural ones.