Master of Engineering Science
Gillies, Elizabeth R.
Self-immolative polymers (SIPs) are molecules that depolymerize in a controlled manner due to the cleavage of stimuli-responsive end groups. End-caps can be cleaved with stimuli such as light, heat, pH changes, and redox conditions. Poly(ethyl glyoxylate) (PEtG) is a SIP that can be modified to adjust its physical and thermal properties. This makes it a suitable platform for various applications that can benefit from stimuli-mediated degradation, such as tissue engineering and drug delivery. This thesis explored the inclusion of functional groups that enable water solubility and cross-linking through click reactions, resulting in a self-immolative hydrogel that degrades upon UV light irradiation. The synthesis steps were confirmed using various techniques, including NMR spectroscopy, infrared spectroscopy, and size exclusion chromatography. It was found that formulations of higher polymer content produced hydrogels that degraded upon UV light irradiation, showing promise for future applications. Further investigation into these hydrogels' physical properties is warranted to understand their potential applications fully.
Summary for Lay Audience
Degradable polymers have garnered a considerable amount of attention over the last few decades due to their reduced waste production and ability to decompose into non-harmful products. These attributes allow for biodegradable polymers to be utilized in a variety of industries including agriculture, commercial goods, and medicine. Recently, degradable polymers have expanded in scope to include a new class of material known as “self-immolative” polymers. These materials are composed of three key components: 1) many repeating units of the same molecule linked together in a chain, 2) molecules attached to each repeat unit that can change the properties of the overall molecule, and 3) a molecule at the end of the chain that can trigger degradation. Through the stimulus-responsive trigger, these materials can decompose rapidly in response to triggers, such as UV light irradiation. To date, the incorporation of these materials into water-based gels has been limited. Water-based gels are currently being investigated for their applications in the medical industry. Depending on their composition, water-based gels can closely mimic the physical properties of a range of tissues. This makes water-based gels an excellent technology for tissue engineering, drug, and cell delivery. This thesis describes the synthesis of water-based gels composed of a photosensitive degradable polymer. The gels were synthesized in a manner that ensured they were not toxic to the human body. The gels demonstrated responsiveness to UV light exposure through measurement of their degradation products and their physical properties were determined through a series of tests that involved swelling the gels in a phosphate-buffered saline solution. Lastly, the robustness of these gels was determined both before and after exposure to UV light and this revealed that the gels decreased in durability following UV light exposure. In summary, this thesis provides a starting point for the viability of utilizing photosensitive degradable polymers in water-based gels and for their future study as drug release and cell scaffold technologies.
Pardy, Jared David, "The Development of Stimuli-responsive Hydrogels from Self-Immolative Polymers" (2023). Electronic Thesis and Dissertation Repository. 9253.
Available for download on Saturday, March 01, 2025