Doctor of Philosophy (PhD)
Sodium deoxycholate (NaDC) is a small bile salt that was used in this dissertation to produce gelation of tris(hydroxymethyl)amino-methane (TRIS) solutions above, below, and near the pKa of NaDC. These solutions respectively yielded a neutral gelator, a charged gelator, and a mixture of each. Impacts of ionic interactions on gel formation were studied in detail and showed that pH can be used to modify many hydrogel properties including sol-gel temperature, crystallinity, and mechanical strength. It was also observed that pH modification of the hydrogels affected nanoparticle formation. Nanoparticles derived from a Group of Uniform Materials Based on Organic Salts (nanoGUMBOS), specifically cyanine-based NIR dyes, were templated within the hydrogel network for potential applications in tissue imaging. These nanoGUMBOS were found to be size-tunable, although material dependent. Several hydrogel formulations yielded a unique rheological finding of two stable regions of elastic modulus. Release of different solutes was investigated under different hydrogel conditions and at variable shear rate. Temperature, solute size, hydrogel formulation, and shear rate were all found to impact solute release. This suggests that NaDC/TRIS hydrogels can be used as injectable, topical, or patch-type drug delivery vehicles or as solute delivery vehicles in applications such as fertilizers and packaging. Enantiopreferential drug release from these hydrogels was also examined. Native gels exhibited significant release preference. This is of great importance to pharmaceutical applications due to the prevalence of racemic drugs. It was found that with facile modification, the enantiopreferential release could be inverted. Further understanding of NaDC/TRIS gelation has broadened the tunability and multidimensional applications of these tailored hydrogel systems. A three-component GUMBOS derived from fluorescein, rhodamine B, and tetradecyltrihexyl phosphonium was synthesized and characterized. Nanoparticles prepared from this GUMBOS exhibited dual-wavelength fluorescence. Ratiometric analysis of these two emission bands revealed changes with pH, specifically between the biologically relevant values of pH 5 and pH 7. Thus, fluorescence microscopy was employed to image cancerous and normal breast cells incubated with nanoGUMBOS. Higher uptake of nanoGUMBOS and more pervasive fluorescence intensity were found in comparison to normal cells, showing great potential for fast, visual determination of cancer cells.
McNeel, Kelsey Elizabeth, "Biomedical Applications of Hydrogels and GUMBOS" (2018). LSU Doctoral Dissertations. 4198.