Emergence of superstructures from a homogeneous lipid sphere.
The spontaneous generation of a periodic hexagonal superstructure on a giant phospholipid sphere (GPS) with a diameter of 20-200 microm was studied. The GPS was composed of ternary phospholipids consisting of dioleoylphosphatidylethanolamine (DOPE), dioleoylphosphatidylcholine (DOPC), and dioleoylphosphatidylinositol-bisphosphate (DOPIP(2)). GPSs were prepared by natural swelling of a lipid film formed on a glass substrate. A GPS with a homogeneous lipid mixture tends to form a two-layered structure between the surface and inner parts; the surface layer is attributed to a DOPIP(2) rich region (we call this layer SL), and the interior is rich in DOPE and DOPC (we call this layer IL). A hexagonal superstructure develops in the SL, and the topology then changes to form multiple-doughnut structures. Finally, myelin-like tubes are generated through symmetry breaking of the doughnutlike structures. The time-dependent change in the surface-area expansion of a GPS is shown to obey the logistic growth model, and this is attributed to the kinetic process of phase segregation between the surface and bulk phase of the GPS.
Negishi
Makiko
M
Kitahata
Hiroyuki
H
Yoshikawa
Kenichi
K
D004926:Escherichia coli / Q000737:chemistry; D007294:Inositol / Q000737:chemistry; D007700:Kinetics; D008055:Lipids / Q000737:chemistry*; D016015:Logistic Models; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D008958:Models, Molecular; D010316:Particle Size; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000737:chemistry; D010716:Phosphatidylinositols / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry
C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; C532047:1,2-dioleoylphosphatidylinositol 4,5-bisphosphate; D008055:Lipids; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D010743:Phospholipids; D007294:Inositol; C017251:1,2-oleoylphosphatidylcholine