Using diffusion-induced growth instabilities to measure line tension at liquid condensed-liquid expanded domain boundaries.

Few techniques exist for measuring the line tension between liquid-condensed (L) and liquid-expanded (L) monolayer phases important to determining monolayer morphology and interfacial mechanical properties. Two-dimensional Mullins-Sekerka (MS) instability theory and non-perturbative fluorescence microscopy and surface pressure-area isotherms are used to evaluate line tension in monolayers of model lung surfactants composed of dipalmitoylphosphatidylcholine, hexadecanol, and cholesterol. The measured line tensions ranging between 7.

Spontaneous evolution of equilibrium morphology in phospholipid-cholesterol monolayers.

Competition between intradomain electrostatic repulsions and interdomain line tension leads to domain shape transitions in phase-separating lipid monolayers. The question remains if these morphologies are energy minima or are kinetically trapped metastable states. We show the reversible evolution of uniform width stripe domains from polydisperse semicircular domains in monolayers of dipalmitoylphosphatidylcholine (DPPC), hexadecanol (HD) or palmitic acid (PA), and dihydrocholesterol (DChol).