title: Large effect of membrane tension on the fluid-solid phase transitions of two-component phosphatidylcholine vesicles.
abstract: Model phospholipid membranes and vesicles have long provided insight into the nature of confined materials and membranes while also providing a platform for drug delivery. The rich thermodynamic behavior and interesting domain shapes in these membranes have previously been mapped in extensive studies that vary temperature and composition; however, the thermodynamic impact of tension on bilayers has been restricted to recent reports of subtly reduced fluid-fluid transition temperatures. In two-component phosphatidylcholine unilamellar vesicles [1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)], we report a dramatic influence of tension on the fluid-solid transition and resulting phases: At fixed composition, systematic variations in tension produce differently shaped solid domains (striped or irregular hexagons), shift fluid-solid transition temperatures, and produce a triple-point-like intersection of coexistence curves at elevated tensions, about 3 mN/m for 30% DOPC/70% DPPC. Tension therefore represents a potential switch of microstructure in responsive engineered materials; it is an important morphology-determining variable in confined systems, and, in biological membranes, it may provide a means to regulate dynamic structure.
authors.affiliation: Departments of Physics and Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003.
authors.forename: Dong
authors.initials: D
authors.lastname: Chen
authors.forename: Maria M
authors.initials: MM
authors.lastname: Santore
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D032701:Biomimetics; D002462:Cell Membrane / Q000378:metabolism*; D002784:Cholesterol / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D021962:Membrane Microdomains / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D013500:Surface Tension; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D010743:Phospholipids; D053835:Unilamellar Liposomes; D015060:1,2-Dipalmitoylphosphatidylcholine; D002784:Cholesterol; C017251:1,2-oleoylphosphatidylcholine
keywords: biomimetic membrane; domain morphology; phase diagram; phase separation; ripple tilt bilayer