Development of Water-Soluble Polyesters for Tissue Engineering Applications
Abstract
The development of tunable polymers has become increasingly important for both tissue engineering and drug delivery. This thesis investigates the development of water-soluble polyesters that contain both natural and synthetic components. These polymers offer tunable chemical structures, as well as functional groups for the conjugation of crosslinking moieties or cell signaling molecules. The first series of polymers was synthesized from poly(ethylene glycol) (PEG) and aspartic acid (Asp) via a titanium catalyzed transesterification method to provide polymers with molar masses of 12 kg/mol. After deprotection, the pendent functional groups of Asp were reacted with methacrylic, maleic, and itaconic anhydride to introduce crosslinkable functional groups. A thermally-initiated crosslinking method was used to prepare hydrogels from the methacrylamide-functionalized polymers. The resulting hydrogels were assessed based on their physical and mechanical properties. High cell content (> 95%) and Young’s moduli of 6 – 9 MPa were obtained were obtained for selected systems. Adipose derived stromal cells were encapsulated within these hydrogels and high cell viabilities indicated that they are promising as scaffolds for potential therapeutic or cell delivery. A second series of polyesters was prepared from PEG, Asp, and itaconic acid, thereby providing polymers with both crosslinkable moieties as well as functional groups for further bioconjugation. The backbone itaconate groups were crosslinked via thermally-initiated free radical crosslinking. Hydrogels were obtained, but the gel content was relatively low, indicating that further optimization of the polymer structure or crosslinking conditions will be needed in the future.