Technology Development for Electrospinning of Novel Biomaterials Structures

Doctoral thesis, 2012

As the population gets older, the demands for new medical treatments increase since many of our most common diseases are related to age, including coronary heart disease, osteoarthritis and chronic ulcers. With this comes an increasing need for new biomaterial structures supporting and promoting tissue regeneration. The work in this thesis aims at developing new technologies based on electrospinning for creating nanofibrous biomaterial structures that mimic human tissues and are suitable for regeneration of damaged tissues and organs. As shown in this thesis, electrospinning has great potential as a design tool for creating body-mimicking nanofibrous materials with control over features from nano- to macro scale. The electrospinning process is highly flexible and allows for creation of nano- to micro sized fibers of a variety of materials and with a wide range of morphologies and structures. Also, there are possibilities of incorporating particles, tuning degradability and combining different materials of different properties. By combining electrospun nanofibers with larger structures (e.g. microfibers, metal surfaces, hydrogels), as described in this thesis, the possibilities are further increased as hierarchical structures are of great interest for the functionality of the material, e.g. the wetting and adhesion properties. This also allows for reinforcement of the otherwise mechanically weak nanofibers. It is shown in this work that electrospun nanofibers may act as reinforcement, despite the weak mechanical properties of the nanofibers, and are of interest for e.g. hydrogels to create possibly injectable scaffolds with appropriate mechanical stability. Porosity and pore sizes are other important limitations of electrospun nanofibrous materials used in biomedical applications. This is addressed in this thesis with the development of nanofiber-coated microfibers, textile fibers with a nanostructured surface which may find use in many different applications where their high surface area and textile processability can be beneficial. However, for tissue engineering purposes the possibility of using them to create highly porous scaffolds are of importance. As shown in the conducted cell studies, the high scaffold porosity allows for complete cell infiltration and study of cell response in relation to porosity and nanofibrous structures in ways that have so far not been possible.