Making Electrospun Spider Silk Fibers Stronger Dan Gil, Blake Taurone, Bailey McFarland, Jusn Jones, Randolph V. Lewis USTAR BioInnovaons Center, Utah State University Logan, Utah Introducon Methods Results Spider silk is one of the most robust FTIR: 0.35 Nylon 66 0.09 Nylon 66 Nylon 66 + 2.5 wt.% MaSp1 Nylon 66 + 2.5 wt.% MaSp1 Nylon 66 + 5 wt.% MaSp1 0.08 • 0.3 Nylon 66 + 5 wt.% MaSp1 Silk dope is loaded in syringe with • Nylon 66 + 10 wt.% MaSp1 MaSp1 contributed to crystallizaon Nylon 66 + 10 wt.% MaSp1 and versale fibers making it a topic 0.07 0.25 1262 of interest in the scienfic posive electrode aached within nylon 6, 6 1640 0.06 0.2 0.05 1280 1238 • Increases in amide I, II, and III 1541 community. Possessing strength and 0.15 0.04 Absorbance Absorbance 0.03 • formaons; indicates H-bonds between 0.1 elascity many have sought to create The target (rotang spindle) has the 0.02 0.05 fibers comparable to natural spider negave electrode aached MaSp1 and nylon 0.01 0 0 • Increases in intensity of α-helices and β- 1700 1650 1600 1550 1500 1320 1300 1280 1260 1240 1220 1200 silk. Up unl recently many sciensts Wavelength (cm-1) Wavelength (cm-1) sheets have fallen short of creang said • 28 kV field is applied forcing fibers. With the use of a technique called electrospinning, comparable polymer ejecon MTS/Mechanical Tesng: • Nylon+MaSp1 (up to 5% wt) has 60 spider silk fibers have been created. Cross-Link Comparison increased elasc modulus and ulmate 50 Electrospinning is the process of • Ejected polymer forms nanofibers 40 tensile strength compared to nylon 30 creang fibers from a polymer collected as a mat Stress (MPa) 20 Control • Cross-linked Nylon+MaSp1 samples 10 XL soluon using an electrical field. This 0 have increased stress with decreased 0 0.1 0.2 0.3 0.4 0.5 0.6 method leads to the formaon of • Mat is rotated into a yarn Strain (mm/mm) nanofibers. These Fibers can then be strain demonstrang further further modified by crosslinking, a modificaon technique tradionally used to • Yarn is then irradiated with the CLIP SEM: analyze protein-protein interacons. to iniate cross-linking • Cross-linked fibers show beer orientaon when compared to control • Diameter of fibers demonstrates nanofiber formaon (100-200 nm) Cross-Linking Modificaons Cross-Linked Control Cross-linking: § Technique tradionally used to analyze protein-to-protein (protein a + protein b) interacons known as Photo-induced cross-linking of Conclusion unmodified proteins (PICUP) CLIP: The design of the CLIP allows for § PICUP is being used to further modify proteins through internal connuous irradiaon reinforcement by creang a direct covalent bond within the spider silk without excessive build up of heat promong proteins longevity of the LED. The • Electrospun spider silk and composite fibers exhibit superb mechanical red arrow points to the § Inially a high powered flashlight was used to iniate PICUP to test cooling system. properes whether or not cross-linking was possible § The Cross-Link Iniang Photodiode or CLIP was created for maximum • Electrospinning allows for producon of mats constructed of mulple cross-linking of spider-silk proteins. nanofibers resulng in resilient fibers/yarns § The CLIP inially contained a broad spectrum LED, with further tesng a specific wavelength (450nm) LED was used to further increase the • Combining spider silk proteins with other polymers (nylon, cellulose, efficiency of cross-linking etc.) appears to increase mechanical properes of the polymers § The 450nm LED was selected because the main cross-linking agent (Ruthenium) is acvated at this wavelength which causes a dityrosine The red arrow indicated • the 450nm LED, specific Using the CLIP, electrospun fibers can be further modified crosslink to form between the spider silk proteins in the fiber for cross-linking. § The CLIP can be used with any biomaterial containing spider silk • Cross-linking iniated by the CLIP can be applied to not only proteins to modify their mechanical properes (lyogels, sponges, fibers, electrospun fibers but any biomaterials containing spider silk proteins films, etc.) § Preliminary experiments show 5-10 fold increase in mechanical strength (control: 2N; cross-linked: 20N)