(473b) Reverse Water-in-Perfluorocarbon Emulsions for Pulmonary Drug Delivery: Effects of Surfactant Concentration on Drug Mass Transfer and Droplet Coalescence
AIChE Annual Meeting
Thursday, November 19, 2020 - 8:15am to 8:30am
Water/PFC emulsions were prepared via sonication with constant fluorescein concentration (used as a drug mimic) in the dispersed aqueous phase, varying water:PFC volume ratios and varying fluorosurfactant concentrations. The emulsion was quiescently contacted with a saline receiving phase in a cuvette to monitor fluorescein uptake over 72 h. Less than 60% of the fluorescein was transferred to the saline phase over 72 h. Mass transfer rates were strongly correlated with fluorosurfactant concentration and the fluorosurfactant:water ratio in a manner suggesting that the rate of aqueous emulsion droplet coalescence with the receiving phase was rate determining, rather than mass transfer through the continuous PFC phase.
Thus, experiments were conducted to measure coalescence times for individual aqueous droplets placed at an aqueous-PFC interface. Coalescence rates were strongly correlated with fluorosurfactant concentration in the PFC phase, primarily via the fluorosurfactant effect on the stability of the thin PFC film separating the drop from the bulk aqueous receiving phase. Furthermore, coalescence rates decreased an order of magnitude with the addition of mucins in the aqueous receiving phase.
Work is ongoing to fully map the correlations between emulsion formulation, stability, fluorescein mass transfer and droplet/receiving phase coalescence rate, including the specific effects of the type of PFC and fluorosurfactant.