Co-surfactant effect of perfluoroalkylated glycerophosphocholines in fluorocarbon emulsions: Dependence on the co-surfactant's hydrophobic chain length

Abstract

Unexpectedly large differences were found when new perfluoroalkylated glycerophosphocholines with slightly different lipidic chains were evaluated as co-surfactants with egg yolk phospholipids (EYP) in the preparation of concentrated buffered (100% w v , i.e., 51.5% v v ) perfluorodecalin emulsions. As co-emulsifier, 1 shows a strong stabilizing effect when compared to a reference emulsion based on natural EYP alone. No significant effect on the emulsion's stability was observed with 2 in spite of the fact that it has the longest fluorophilic F-alkyl tail. Compound 3, which has the shortest lipidic chain length, demonstrated strong destabilizing properties at the time of the preparation of the emulsion. These stabilizing/destabilizing effects are rationalized in terms of interactions of the surfactant's perfluoroalkylated tail with the fluorocarbon phase or with the hydrocarbon chains of the EYP. Stabilizing effects become predominant only when the surfactant's total chain length is comparable to the EYP monolayer's thickness, which is the case for 1.