Langmuir monolayer miscibility of perfluorocarboxylic acids with biomembrane constituents at the air-water interface.

Over the past two or three decades, Langmuir monolayers comprising various fluorinated amphiphiles such as perfluorinated, partially fluorinated, and fluorinated-hydrogenated hybrid molecules at the air-water interface, have been investigated to deepen the understanding of their characteristic phenomena and to explore the mutual interaction of these amphiphiles with biomembrane constituents. Langmuir monolayers of these fluorinated amphiphiles are potentially applicable in the fields of materials, biological and clinical science, where they may be utilized in two-dimensional protein crystallization, microelectronics, and for surfactant replacement in the lung. This review article focuses on the miscibility between perfluorinated long-chain carboxylic acids (CF₃(CF₂)(n-1)COOH, or FnCOOH) and phospholipids or fatty acids in biomembranes upon lateral compression, and describes how the chain-length mismatch between the fluorinated and the hydrogenated tails relates to the interfacial phase behavior from the thermodynamic and the morphological aspects at the micrometer and nanometer levels.