Strategies for Making High‐Performance Artificial Spider Silk Fibers

Abstract

Artificial spider silk is an attractive material for many technical applications since it is a biobased fiber that can be produced under ambient conditions but still outcompetes synthetic fibers (e.g., Kevlar) in terms of toughness. Industrial use of this material requires bulk‐scale production of recombinant spider silk proteins in heterologous host and replication of the pristine fiber's mechanical properties. High molecular weight spider silk proteins can be spun into fibers with impressive mechanical properties, but the production levels are too low to allow commercialization of the material. Small spider silk proteins, on the other hand, can be produced at yields that are compatible with industrial use, but the mechanical properties of such fibers need to be improved. Here, the literature on wet‐spinning of artificial spider silk fibers is summarized and analyzed with a focus on mechanical performance. Furthermore, several strategies for how to improve the properties of such fibers, including optimized protein composition, smarter spinning setups, innovative protein engineering, chemical and physical crosslinking as well as the incorporation of nanomaterials in composite fibers, are outlined and discussed.

Spiders Use Structural Conversion of Globular Amyloidogenic Domains to Make Strong Silk Fibers

“…[ 49 ] This improvement in mechanical strength is attributed to the spacer domain by facilitating the formation of a more compact alignment of protein chains in the fibers, supported by the significantly smaller diameters of the fibers observed (Figure 5c) and the intrinsic fluorescence distribution (Figure 5k). It has been shown that larger proteins only give stronger fibers if the fibers are post‐stretched, which is likely due to the forming of more aligned proteins during this procedure, [ 49 ] supporting the importance of molecular homogeneity with regard to fiber mechanical properties.…”

“…In a recent correlation analysis employing accessible data on the mechanical properties of synthetic spider MaSp/MiSp silk fibers, findings suggested that an elevated count of poly‐Ala repeats, and consequently, a higher molecular weight of the engineered spidroin is linked to enhanced fiber strength, specifically in post‐stretched fibers, [ 49 ] suggesting the importance of high molecular weight in spidroins for achieving strong mechanical properties. Indeed, various approaches have been explored to generate larger recombinant spidroins, such as intein‐mediated splicing, [ 50–52 ] transgenic silkworm techniques, [ 53 ] and engineered E. coli .…”

Tough, Highly Transparent, and Wear Resistant Polyurethane–Calcium Phosphite Oligomer Organic–Inorganic Hybrid Nanocomposite

“…The resulting material is exceptionally robust due to the high energy consumption required for breaking and reforming these bonds when subjected to external forces. This characteristic makes spider silk one of the most durable natural materials. − With a deeper understanding of the natural materials’ structure, thermoplastic polyurethane (PU) has received great attention as a biomimetic polymer substrate that can easily simulate the tough and soft structure of spider silk. − …”

Bioinspired Mechanically Robust and Recyclable Hydrogel Microfibers Based on Hydrogen‐Bond Nanoclusters

“…Biomimicking the hierarchical structure of spider silk provides a promising strategy to construct structural fiber materials, which can be used in energy‐dissipation and shock‐absorbing applications. [ 6 , 7 , 8 , 9 ] However, tremendous efforts have been focused on the development of spider silk‐like fibers based on regenerated silk proteins, [ 10 , 11 , 12 ] and thus using a non‐polypeptide approach to prepare those fibers is still difficult.…”