Studies on the formation and stability of perfluorodecalin nanoemulsions by ultrasound emulsification using novel surfactant systems

Low-molecular weight perfluorocarbons (PFC) are suitable for therapeutic/biomedical applications involving O₂/CO₂/NO capture, transport and release (e.g., blood substitutes). However, PFC-in-Water emulsions face challenges related to inadequate emulsion stability, wide-sized droplet distribution and reduced shelf-life, which may be tackled by producing PFC-based nanoemulsions. A novel surfactant system comprising of Tween 80 and (1H,1H,2H,2H-perfluorooctyl)phosphocholine (FC8) was explored to produce monomodal narrow-sized distribution of PFC-in-Water nanoemulsions by ultrasound emulsification. Perfluorodecalin (PFD) was used as the model PFC. Surfactant solutions and emulsions were characterised for surface tension, interfacial tension and emulsion kinetic stability. In comparison to Tween 80, at 4.3 mM, the fluorinated FC8 surfactant-based emulsion droplets were 32 % smaller and six times more stable. Reduction of interfacial tension from 41.5 ± 0.5 mN.m⁻¹ for Tween 80 alone to 20.7 ± 1.8 mN.m⁻¹ for FC8 alone was related to better droplet size distribution of resultant emulsion, with a decrease in Z_avg from 255.4 ± 3.9 nm to 172.8 ± 0.72 nm. Equimolar mixture of surfactants resulted in Z_avg of 175.8 ± 1.1 nm at a reduced sonication time of 15 min, leading to safer surfactant system with lower energy and operating costs for emulsions preparation.