Spider Silk Biocomposites: From Recombinant Protein to Fibers
Spider silk has extraordinary mechanical properties, containing a unique balance of high-tensile strength and extensibility. Spider silks outperform several well-known manmade materials including high-tensile steel, Kevlar (body armor), and nylon. Modern spiders spin at least six to seven different fiber types that have distinct mechanical properties. These fibers have been shown to be biocompatible, heat stable and environmentally green materials. Because of their unique mechanical features, scientists are pursuing spider silks as next generation biomaterials that can be used for a broad range of applications. Given the cannibalistic nature of spiders, combined with their venomous nature, farming spiders for silk becomes a dangerous and impractical method for obtaining large amounts of silk for industrial applications. This has prompted scientists to develop DNA methodologies and heterologous protein expression systems that produce vast quantities of recombinant silk proteins. Some potential applications of silks spun from recombinant proteins include body armor, ropes and cords, sutures, tissue scaffolds, tires, and shoes. Here we cover the following topics: the diverse protein nature of spider silks and the compositions of threads, the method and steps for synthetic silk production, and the translation of fiber production from a small scale to a large-scale spinning platform. By drawing upon advances in spinning methodologies, we will describe the development of spider silk fiber composites using full-length silk proteins retrieved from the major ampullate silk-producing gland blended with other recombinant proteins expressed and purified from microorganisms.