Technical Part: Spider silks exhibit excellent strength, stiffness, and toughness simultaneously, a feat unachievable in most synthetic structural materials. However, natural silks cannot be harvested in quantities necessary for applications. Recombinant silk proteins closely mimicking the natural silk sequences have been synthesized in processes that can be further scaled up. However, fibers made from these proteins, while they are tough, are significantly inferior to natural fibers in the important metrics of strength. Much has been learned in recent years about the effects of various protein motifs on mechanical properties. Despite a very intensive effort in many laboratories, reproduction of the native fiber spinning process resulting in highly structured strong and tough fiber has so far proven elusive. The objective of this project is to develop and study novel nanostructured synthetic spider silk fiber based on continuous silk nanofilaments. Rather than trying to replicate the elusive exact conditions of the delicate native structuring process via self-assembly, biomimetic hierarchical silk fibers will be built using a recently optimized top-down nanomanufacturing technique. The technique is capable of producing highly aligned and dense nanofilamentary fibers with simultaneously improved strength, modulus, and strain at failure, compared to the solid microfibers from the same polymer. Preliminary studies show impressive properties for individual ultrafine nanofibers electrospun from two different synthetic spider silk proteins. These properties will be further improved by precision-manufactured microscopic nanofilamentary fibers. These fibers will be analyzed using solid state NMR, FTIR, and X-ray diffraction to determine the structural elements responsible for the best materials properties. These biomimetic constructs, combined with the original potential of spider silk proteins can lead to revolutionary new fibers that can be produced in industrial quantities. Expectations are to develop synthetic spider silk fibers exceeding the mechanical performance of the natural fibers, thus improving on nature's best structural material. This research will build on the complimentary interdisciplinary expertise and several recent breakthroughs in the laboratories of the co-PIs.
Non-Technical Part: The extreme flexibility of the electro-spinning process and recently developed precision methods of process control, based on sophisticated multi-physics process modeling, open up near unlimited possibilities for the development of new high-performance nanostructured fibers. These next generation ultrastrong/tough fibers promise broad applications. Both research groups have proven records of commercializing research results including advanced supercomposites with nanofiber reinforced interfaces for military applications and spider silk fibers for tendon repair materials, sporting goods, and military protective materials. The two Universities will partner strategically to further develop and commercialize the unique ultrahigh-performance nanoflamentary synthetic spider silk fibers developed under this grant. Two PhD students with different backgrounds will interact and work closely with each other and the co-PIs. At least 5 undergraduates from both universities will also be involved with this research program. In addition senior design project groups will be joining the research to test various applications of these fibers. The proposed research covers biochemistry, mechanics, materials science, and nanomanufacturing and will provide students a unique interdisciplinary experience. Undergraduate students will present their results at Undergraduate Research Day. Both laboratories will be involved with their universities' efforts to recruit underrepresented groups, particularly providing laboratory tours and hands on efforts for high school students. A new nanostructured silk design, fabrication, and characterization testbed will be developed as part of the UNL Nanofiber Core Facility. This testbed will be used for demonstrations during frequent visits to our laboratories of fellow researchers, students, and members of the public in classes, and for research. This facility testbed will also serve as a vehicle for dissemination of new research results. Previous research from both groups has been featured in the popular press as well as several television programs both in the U.S. and in several other countries. Of specific note is that this research was featured on NSF's Science Nation program as well as Nova's "Making Stuff" and the Discovery, History and Disney Channels. The two groups will continue to jointly popularize this exciting research performed at the two universities.
