Fiber Processing of Recombinant Spider Silk Proteins

Spider silks are protein-based fibers well known for their tensile strength, elasticity, and extraordinary toughness. However, spider silk has not yet been found to enter many products, since harvesting natural spider silk is highly inefficient. Recombinant production of the underlying spider silk proteins in microbial hosts offers an alternative to develop silk materials for distinct applications. In this context, it is crucial to mimic the spinning dope preparation and the spinning process of spiders to achieve nature-like fiber properties, since the mechanical properties of the fibers differ significantly depending on the utilized spinning method. In contrast, nonnatural spinning techniques facilitate the fabrication of silk fibers with tunable new properties for diverse technical applications. Electrospinning, for instance, produces fibers with diameters in the submicrometer regime, forming meshes ideal, e.g., for filtration. Centrifugal electrospinning increases fiber throughput, making it suitable for scale-up production. Even hierarchical structures can be created by combining 3D printing and centrifugal electrospinning within a single device, or yarn electrospinning combined with textile techniques, enabling complex architectures. This perspective article highlights how different spinning approaches broaden the potential uses of silk-based materials across various application fields, utilizing the benefits of intrinsic silk characteristics in combination with advanced technical features.