title: Stable polymeric nanoballoons: lyophilization and rehydration of cross-linked liposomes.
abstract: The cross-linking of supramolecular assemblies of hydrated lipids is an effective method to stabilize these assemblies to disruption by surfactants or aqueous alcohol. The heterobifunctional lipids, Acryl/DenPC(16,18) and Sorb/DenPC(18,21), are examples of a new class of polymerizable lipid designed for the creation of cross-linked lipid structures. The robust nature of cross-linked liposomes was demonstrated by lyophilization of the liposomes followed by their essentially complete redispersion in water. The resulting liposomes were compared to the original sample by quasi-elastic light scattering and transmission electron microscopy. There was no major change in the size or structure of the cross-linked liposomes after rehydration of the freeze-dried powder of liposomes. Moreover, the rehydrated cross-linked liposomes continued to be resistant to surfactant solubilization. Neutral cross-linked liposomes were predominantly redispersed after freeze-drying with the aid of bath sonication. The small amount of residual liposome aggregation observed with neutral liposomes could be prevented by incorporating a surface charge into the liposome or attaching hydrophilic polymers, for example, poly(ethylene glycol), onto the liposome.
authors.affiliation: Department of Chemistry, Carl S. Marvel Laboratories, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: Sanchao
authors.initials: S
authors.lastname: Liu
authors.forename: David F
authors.initials: DF
authors.lastname: O'Brien
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry; D005612:Freeze Drying; D008051:Lipid Bilayers / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D036103:Nanotechnology; D012995:Solubility; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D008051:Lipid Bilayers; D008055:Lipids; D008081:Liposomes; D014867:Water