title: Spontaneously formed monodisperse biomimetic unilamellar vesicles: the effect of charge, dilution, and time.
abstract: Using small-angle neutron scattering and dynamic light scattering, we have constructed partial structural phase diagrams of lipid mixtures composed of the phosphatidylcholines dimyristoyl and dihexanoyl doped with calcium ions (Ca2+) and/or the negatively charged lipid, dimyristoyl phosphatidylglycerol (DMPG). For dilute solutions (lipid concentration < or =1 wt %), spontaneously forming unilamellar vesicles (ULVs) were found, and their polydispersity was determined to be approximately 20%. The stability of the Ca2+- or DMPG-doped ULVs was monitored over a period of 4 days and their structural parameters (e.g., average outer radius, <Ro>) were found to be insensitive to the lipid concentration (Clp). However, doping the dimyristoyl/dihexanoyl system with both Ca2+ and DMPG resulted in ULVs whose <Ro> was found to be Clp dependent. The <Ro> of DMPG-doped ULVs remained unchanged over an extended period of time (at least 4 days), a good indication of their stability.
authors.affiliation: National Research Council Canada, Steacie Institute for Molecular Sciences, Chalk River, Ontario K0J 1J0, Canada.
authors.forename: M-P
authors.initials: MP
authors.lastname: Nieh
authors.forename: T A
authors.initials: TA
authors.lastname: Harroun
authors.forename: V A
authors.initials: VA
authors.lastname: Raghunathan
authors.forename: C J
authors.initials: CJ
authors.lastname: Glinka
authors.forename: J
authors.initials: J
authors.lastname: Katsaras
mesh_terms: D002118:Calcium / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D008823:Micelles; D033363:Neutron Diffraction / Q000379:methods; D010713:Phosphatidylcholines / Q000737:chemistry*; D010715:Phosphatidylglycerols / Q000737:chemistry*
chemical_list: D008081:Liposomes; D008823:Micelles; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; C002773:dimyristoylphosphatidylglycerol; D002118:Calcium