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Development of electrically conductive porous silk fibroin/carbon nanofiber scaffolds

Tufan, Yiğithan
Tissue engineering applications typically require porous scaffolds which provide requisite surface area for cellular functions, while allowing nutrient, waste and oxygen transport with the surrounding tissues. Concurrently, scaffolds should ensure sufficient mechanical properties to provide mechanically stable frameworks under physiologically relevant stress levels. Furthermore, electrically conductive platforms are also desired for the regeneration of specific tissues, where electrical impulses are transmitted throughout the tissue for proper physiological functioning. Towards this goal, silk fibroin (SF) from Bombyx mori silkworms captured significant interest in tissue engineering applications due to its tuneable mechanical properties and ability to promote cellular functions. In this thesis, carbon nanofibers (CNFs) were incorporated into porous SF matrix as a secondary phase to provide electrical conductivity and enhance mechanical properties of SF. In the meantime, pore size and porosity of SF/CNF nanocomposite scaffolds were controlled during scaffold fabrication via the salt leaching process. For the developed scaffold fabrication protocol, CNFs were dispersed in SF owing to the hydrogen bond forming ability of hexafluoro-2-propanol (HFIP), a fluoroalcohol-based solvent used for SF. Results showed that SF/CNF nanocomposite scaffolds having electrical conductivities and tangent modulus values as high as 0.04 S/cm and 260 ± 30 kPa, respectively, were fabricated. In the meantime, these SF/CNF nanocomposite scaffold had pore size of 376 ± 53 µm and porosity as high as 78%. Furthermore, ~34% increase in the wettability of SF was achieved upon the incorporation of 10% CNF in SF scaffolds, which contributed to the enhanced fibroblast spreading on SF/CNF nanocomposite scaffold surfaces.