title: Liquid-liquid domain miscibility driven by composition and domain thickness mismatch in ternary lipid monolayers.
abstract: This work describes how changes in surface pressure modulate the molecular organization of Langmuir monolayers formed by ternary mixtures of dlPC/pSM/Dchol that exhibit coexistence of liquid-expanded (LE) and liquid-ordered (Lo) phases. It provides a theoretical framework for understanding the pressure-induced critical miscibility point characteristic of monolayer systems with liquid-liquid phase coexistence. From compression isotherms and Brewster angle microscopy of Langmuir monolayers with a composition close to a tie line, we determined experimental values of mean molecular areas, surface potential, and monolayer thickness and could estimate the mean molecular area and composition of each coexisting phase. A surface-pressure-induced enrichment of the PC component in the Lo phase reduces both the compositional miscibility gap and the hydrophobic mismatch between phases. The liquid-liquid miscibility transition point observed at ≈25 mN/m can be explained by a competition between thermal energy and the line tension arising from the hydrophobic mismatch between the coexisting liquid phases.
authors.affiliation: Departamento de Química Biológica, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Facultad de Ciencias Químicas, CONICET, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba, Argentina. lfanani@ fcq.unc.edu.ar
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Fanani
authors.forename: Bruno
authors.initials: B
authors.lastname: Maggio
mesh_terms: D000465:Algorithms; D057927:Hydrophobic and Hydrophilic Interactions; D008055:Lipids / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry; D011312:Pressure
chemical_list: D008055:Lipids; D010713:Phosphatidylcholines; C002448:1,2-linoleoylphosphatidylcholine