Biofabrication using spider silk proteins
Proteins reflect one fascinating class of natural polymers with huge potential for technical as well as biomedical applications. One well-known example is spider silk, a protein fiber with excellent mechanical properties such as strength and toughness. We have developed biotechnological methods using bacteria as production hosts which produce structural proteins mimicking the natural ones [1, 2]. Besides the recombinant protein fabrication, we analyzed the natural assembly processes and we have developed spinning techniques to produce protein threads closely resembling natural silk fibers. In addition to fibers, we employ silk proteins in other application forms such as hydrogels, particles or films with tailored properties, which can be employed especially for biomaterials applications .
We could e.g. design spider silk-based sheets and scaffolds that prevent adherence of microbes. Without adherence biofilm formation cannot occur, which lowers the frequency of infections in surgical patients. However, the spider silk sheets and scaffolds do not kill any cells. Unlike current treatments they prevent infestation to begin with. The designed spider silk scaffolds are even bio selective, meaning that this designer silk repels microbes while allowing human cell attachment and proliferation . Spider silk hydrogels can be even employed as bioinks for biofabrication (i.e. 3D bioprinting together with cells) , but also non-aqueous solvents can be used to 3D-fabricate spider silk scaffolds . Their elastic behavior dominates over the viscous behavior over the whole angular frequency range with a low viscosity flow behavior and good form stability. No structural changes occur during the printing process, and the hydrogels solidify immediately after dispense plotting. Due to the form stability it was possible to directly print multiple layers on top of each other without structural collapse. Cell-loaded spider silk constructs can be easily printed without the need of additional cross-linkers or thickeners for mechanical stabilization. Encapsulated cells show good viability in such spider silk hydrogels. Exemplarily, we use 3D-printed spider silk scaffolds for the growth of heart muscle patches [7, 8] or for generating nerve guiding conduits [9, 10].
 Heidebrecht, A., Scheibel T. (2013). Recombinant production of spider silk proteins. Adv. Appl. Microbiol. 82, 115-153
 Saric, M., Eisoldt, L., Döring, V., Scheibel, T. (2021) Interplay of Different Major Ampullate Spidroins During Assembly and Implications for Fiber Mechanics. Advanced Materials 33, 2006499
 Aigner, T.B., DeSimone, E., Scheibel T. (2018) Biomedical applications of recombinant silk-based materials. Advanced Materials 30, 1704636
 Kumari, S., Lang, G., DeSimone, E., Spengler, C., Trossmann, V., Lücker, S., Hudel, M., Jacobs, K., Krämer, N., Scheibel, T. (2020) Engineered spider silk-based 2D and 3D materials prevent microbial infestation. Materials Today, 41, 21-33
 Schacht, K., Jüngst, T., Schweinlin, M., Ewald, A., Groll, J., Scheibel, T. (2015) Biofabrication of cell-loaded, 3D recombinant spider silk constructs. Angew. Chem. Int. Ed., 54, 2816-2820
 Neubauer, V., Trossmann, V., Jacobi, S., Döbl, A., Scheibel, T. (2021) Aqueous-Organic Solvent Derived Recombinant Spider Silk Gels as Depots for Drugs. Angew. Chem. Int. Ed., 60 DOI:10.1002/anie.202103147
 Petzold, J. Aigner, T., Touska, F., Zimmermann, K., Scheibel, T., Engel, F. (2017) Surface features of recombinant spider silk protein eADF4(κ16)-made materials are well-suited for cardiac tissue engineering. Adv. Funct. Mat. 27, 1701427
 Kramer, J., Aigner, T., Petzold, J., Roshanbinfar, K., Scheibel, T., Engel, F. (2020) Recombinant spider silk protein eADF4(C16)-RGD coatings are suitable for cardiac tissue engineering. Sci Reports 10, 8789
 Pawar, K., Welzel, G., Haynl, C., Schuster, S., Scheibel, T. (2019) Recombinant Spider Silk and Collagen-Based Nerve Guidance Conduits support Neuronal Cell Differentiation and Functionality in vitro. ACS Appl. Bio Mater. 2, 4872-4880
 Aigner, T.B., Haynl, C., Salehi, S., O’Connor, A., Scheibel, T. (2020) Nerve guidance conduit design based on self-rolling tubes. Materials Today Bio 5, 100042