title: Nanoscale phase separation in DSPC-cholesterol systems.
abstract: The lipid arrangement of eukaryotic cell membranes has been shown to be heterogeneous, with domains enriched in cholesterol and saturated phospholipids, coexisting with a continuous phase that is enriched in unsaturated phospholipids. While the existence of these domains is well-established, there is still a lack of consensus regarding domain size and the factors influencing it. In this work, we investigate model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)-1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)-cholesterol (Chol) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC, 18:1-16:0)-DSPC-Chol with a steady-state fluorescence assay and report the influence of phospholipid chain saturation and chain length on domain size. The spectral shifts of 1-myristoyl-2-[12-[(5-dimethylamino-1-naphthalenesulfonyl)amino]dodecanoyl]-sn-glycero-3-phosphocholine (DAN-PC) and a Förster resonance energy transfer (FRET) assay were used, along with an analytical model, to estimate domain sizes. A region of nanoscale domain existence was observed in both ternary systems; however, the domains formed in the system containing the asymmetric lipid (POPC, 18:1-16:0) were larger than those formed in the diunsaturated lipid (DOPC, 18:1-18:1). This is a new finding, as domains were not previously known to exist in similar POPC-based systems.
authors.affiliation: Department of Chemical and Biological Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Brown
authors.forename: Steven P
authors.initials: SP
authors.lastname: Wrenn
mesh_terms: D002784:Cholesterol / Q000302:isolation & purification*; D049329:Nanostructures / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000302:isolation & purification*
chemical_list: D010713:Phosphatidylcholines; D002784:Cholesterol; C010942:1,2-distearoyllecithin