New sterically stabilized vesicles based on nonionic surfactant, cholesterol, and poly(ethylene glycol)-cholesterol conjugates.
Monomethoxypoly(ethylene glycol) cholesteryl carbonates (M-PEG-Chol) with polymer chain molecular weights of 1000 (M-PEG1000-Chol) and 2000 (M-PEG2000-Chol) have been newly synthesized and characterized. Their aggregation behavior in mixture with diglycerol hexadecyl ether (C16G2) and cholesterol has been examined by cryotransmission electron microscopy, high-performance gel exclusion chromatography, and quasielastic light scattering. Nonaggregated, stable, unilamellar vesicles were obtained at low polymer levels with optimal shape and size homogeneity at cholesteryl conjugate/ lipids ratios of 10 mol% M-PEG1000-Chol or 5 mol% M-PEG2000-Chol, corresponding to the theoretically predicted brush conformational state of the PEG chains. At 20 mol% M-PEG1000-Chol or 10 mol% M-PEG2000-Chol, the saturation threshold of the C16G2/cholesterol membrane in polymer is exceeded, and open disk-shaped aggregates are seen in coexistence with closed vesicles. Higher levels up to 30 mol% lead to the complete solubilization of the vesicles into disk-like structures of decreasing size with increasing PEG content. This study underlines the bivalent role of M-PEG-Chol derivatives: while behaving as solubilizing surfactants, they provide an efficient steric barrier, preventing the vesicles from aggregation and fusion over a period of at least 2 weeks.
Beugin
S
S
Equipe Physico-Chimie des Systèmes Polyphasés, URA CNRS 1218, Université Paris-Sud, Châtenay-Malabry, France.
Edwards
K
K
Karlsson
G
G
Ollivon
M
M
Lesieur
S
S
D002784:Cholesterol / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D004548:Elasticity; D005615:Freezing; D005995:Glyceryl Ethers; D007202:Indicators and Reagents; D008027:Light; D008854:Microscopy, Electron; D008968:Molecular Conformation; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D012542:Scattering, Radiation; D013055:Spectrophotometry, Infrared; D013500:Surface Tension; D013501:Surface-Active Agents
D005995:Glyceryl Ethers; D007202:Indicators and Reagents; D013501:Surface-Active Agents; C086133:diglycerol hexadecyl ether; C113813:monomethoxypoly(ethylene glycol)cholesteryl carbonate; D011092:Polyethylene Glycols; D002784:Cholesterol