In the present work, the relationship between structural characteristics and functional performance in polyglycerol polyricinoleate (PGPR) stabilised water-in-oil (W/O) emulsions was investigated. Novel W/O emulsions with a PGPR concentration of 4%, and oil volume fractions (φO) of 0.7 and 0.8 showed the smallest mean droplet size (~5 μm) and highest emulsification index (~97%). Both W/O emulsions showed shear-thinning and elastic-dominant properties with a weak frequency dependence. Both W/O emulsions possessed superior thixotropic recovery properties with recovery percentages of 131.26% (φO = 0.7) and 114.56% (φO = 0.8). The thermo-responsive properties could be closely related to the PGPR aggregation induced by hydrophobic interaction and interfacial rearrangement. The present work helped to design and develop functional W/O emulsions as alternatives to butter spreads, bio-lubricants, and other thermo-responsive delivery systems.
Ureteric stricture is a long-term condition that can lead to the obstruction in the urinary tract, leading to hydronephrosis and kidney failure. Current therapies are invasive and ineffective in managing stricture recurrence following stenting. It is hypothesized that a bilayer swellable drug-eluting stent (BSDES) that can co-apt with the urothelium for the localized and sustained delivery of drugs into the diseased section can reduce or eliminate stricture recurrence. The BSDES comprises of two layers of coatings. The first layer consists of mitomycin C (MMC) and 70/30 poly-L-lactide-co-caprolactone (PLC). The second layer consists of polyethylene glycol diacrylate (PEGDA) hydrogel. The first layer is needed for sustained release of drug while the second layer is required for close contact with urothelial wall. This thesis examines the development, fabrication, characterization and evaluation of a BSDES, the results achieved as below: Firstly, mass loss and rheological measurements identified 10% w/v PEGDA hydrogel as the candidate hydrogel concentration since there was no significant degradation and it could retain the largest mechanical strength over the 4 weeks. Secondly, plasma treatment (100W, 5 min) was found to be effective in improving the interfacial adhesion between the hydrogel and polymer, allowing the hydrogel to adhere on the stent over the 4 weeks. Moreover, drug release studies were conducted in the static conditions over 1 month. Tunable drug release was demonstrated in the static condition by varying the polymer thickness and drug concentration. In addition, the drug released in the static condition was well above the minimum effective concentration to inhibit HBdSF (0.01 ug/mL). An in-vitro transwell cell study showed that the drug eluted from the coated stent was able to inhibit human bladder stroma fibroblasts (HBdSF) in-vitro.
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