From relaxation to buckling: A continuum elastic framework connecting surface instabilities of highly compressed lipid thin films.

Self-assembled thin films respond to external loads via surface instabilities that are critical to their functionality in both biology and technology. Lipid monolayers at the air-liquid interface are one such system. Tunability between out-of-plane buckling (e.

Chemical potential measurements constrain models of cholesterol-phosphatidylcholine interactions.

Bilayer membranes composed of cholesterol and phospholipids exhibit diverse forms of nonideal mixing. In particular, many previous studies document macroscopic liquid-liquid phase separation as well as nanometer-scale heterogeneity in membranes of phosphatidylcholine (PC) lipids and cholesterol. Here, we present experimental measurements of cholesterol chemical potential (μ) in binary membranes containing dioleoyl PC (DOPC), 1-palmitoyl-2-oleoyl PC (POPC), or dipalmitoyl PC (DPPC), and in ternary membranes of DOPC and DPPC, referenced to crystalline cholesterol.