Fundamental Studies on Spider Egg Case Silk Biomaterials and their Mimics

Arizona State University, Scottsdale AZ

Investigators

Abstract

Non-Technical Summary Silk is a fascinating, naturally occurring biomaterial that has had a large impact on human civilization. Although silkworm silk is the most investigated biomaterial, in part because of wide availability, the diversity of spider silks available can lead to new generations of hitherto unexplored biomaterials. Spiders produce many different forms of silk including ones used to construct egg cases. Spider egg case silk proteins and biopolymer fibers have scarcely been studied, compared to spider dragline silk (commonly used to as the scaffolding of spider webs) and silkworm silk. Yet, its mechanical properties (i.e., toughness) and conserved and repetitive gene sequence have been studied and shown to be significantly different from other spider silks. The molecular structure- and mechanical-function relationship in spider egg case silks and biomaterial composites with nanoparticles will allow for the development of new bionanomaterials with predictably tunable optical, mechanical and thermal properties. This biomaterials research brings together aspects of biochemistry, biomaterials and bioengineering, which requires a diverse scientific team, including physicists, chemists, biochemists and bioengineers from Arizona State University (ASU) and collaborations with Argonne National Laboratory (ANL). This multi-institutional and multi-disciplinary research will expose graduate, undergraduate and high school students to modern transdisciplinary research and modern communication and teamwork tools for building and maintaining research across multiple labs and institutes. Technical Summary Spiders produce different forms of silk proteins or spidroins, of which, tubuliform and aciniform silk is used to construct egg cases. The mechanical properties (i.e., toughness) and conserved and repetitive gene sequence are known for many spider’s egg case silk proteins and shown to be significantly different from other proteins used to make the more commonly studied dragline spider silks. The proposed research team plans to explore the structure-function relationship in spider egg case silks, spider silk polypeptides derived from spider egg case silk protein motifs, and biomaterial nanocomposites of egg case silks with nanoparticles. Using recently developed methods for obtaining appreciable quantities of isotopically enriched spider egg case silks, molecular structure and dynamics will be investigated using advanced magnetic resonance techniques. Besides natural spider silks, significant effort will be placed on peptide mimics derived from spider egg case proteins repetitive motifs, allowing structure-function studies, self-assembly and potentially in the long-term overcoming the bioproduction bottleneck for practical application. Using both spider silk polypeptides and processed spider egg case silk, nanoparticle-silk composite biomaterials with tunable properties will be designed and generated for specific biomaterials applications. The biocompatibility of the spider silk polypeptides, their mimics and nanocomposites will be studied comprehensively in vitro and in vivo. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.