Oligo [poly(ethylene glycol) fumarate] gels with photo-sensitive pendent groups
Abstract
Stimuli-responsive hydrogels are 3D polymeric structures that offer attractive qualities within the biomedical field due to their excellent biocompatibility and tunability to be employed in drug release, wound healing, and implants. Aliphatic polyesters are biodegradable polymers that naturally degrade by the process of simple ester hydrolysis. Oligo[poly(ethylene glycol) fumarate] (OPF) is a linear polyester containing repeating units of poly(ethylene glycol) and unsaturated fumarate. OPF naturally degrades through hydrolytic cleavage into poly(ethylene glycol) (PEG) and fumaric acid which is a naturally occurring compound found in the Kreb’s cycle. However, in some cases, it would be beneficial to activate or accelerate this degradation in a more controlled manner. This thesis explores the degradative behaviour of OPF functionalized with photoactivatable pendent groups that undergo intramolecular cyclization to cleave the backbone, thereby degrading the polymer. Next, the functionalized OPF is converted into a hydrogel by covalently cross-linking and the gel is characterized by the gel content and equilibrium water content. Hydrogel degradation is examined by 1H NMR spectroscopy and mechanical testing with and without UV light irradiation. It is shown that activation of the pendent groups can accelerate gel degradation.