Spontaneously formed monodisperse biomimetic unilamellar vesicles: the effect of charge, dilution, and time.
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.
Nieh
M-P
MP
National Research Council Canada, Steacie Institute for Molecular Sciences, Chalk River, Ontario K0J 1J0, Canada.
Harroun
T A
TA
Raghunathan
V A
VA
Glinka
C J
CJ
Katsaras
J
J
D002118:Calcium / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D008823:Micelles; D033363:Neutron Diffraction / Q000379:methods; D010713:Phosphatidylcholines / Q000737:chemistry*; D010715:Phosphatidylglycerols / Q000737:chemistry*
D008081:Liposomes; D008823:Micelles; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; C002773:dimyristoylphosphatidylglycerol; D002118:Calcium