title: Effects of the acyl chain composition of phosphatidylcholines on the stability of freeze-dried small liposomes in the presence of maltose.
abstract: The effects of the acyl chain composition of phosphatidylcholines (PCs) on the stability of small unilamellar vesicles during freeze-drying and rehydration in the presence of maltose were studied by monitoring the retention of a trapped marker, calcein, in the internal liposome compartment. In dipalmitoyl PC, beta-oleoyl-gamma-palmitoyl-PC and egg yolk PC liposomes, good or fair retentions (>50%) were observed in the presence of maltose, but maltose was ineffective in preserving retention in the dioleoyl PC (DOPC) liposomes (<10%). The extremely low retention in the DOPC liposome was ascribed to neither a formation of the inverted hexagonal phase of the liposomal membrane nor the fusion/aggregation of the liposomes in the drying-rehydration process. Differential scanning calorimetry measurements suggested that interactions of maltose with PC headgroups were essential to stabilizing the dry liposomes. These interactions were significant in the saturated or mixed chain liposomes but were markedly reduced in the DOPC liposomes.
authors.affiliation: Division of Drugs, National Institute of Health Sciences, Osaka, 540-0005, Japan. hiroaki.komatsu@mail.tju.edu
authors.forename: H
authors.initials: H
authors.lastname: Komatsu
authors.forename: H
authors.initials: H
authors.lastname: Saito
authors.forename: S
authors.initials: S
authors.lastname: Okada
authors.forename: M
authors.initials: M
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Egashira
authors.forename: T
authors.initials: T
authors.lastname: Handa
mesh_terms: D002152:Calorimetry, Differential Scanning; D004347:Drug Interactions; D005227:Fatty Acids / Q000032:analysis* / Q000494:pharmacology; D005452:Fluoresceins / Q000493:pharmacokinetics; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D005612:Freeze Drying / Q000379:methods / Q000592:standards; D008081:Liposomes / Q000737:chemistry*; D008320:Maltose / Q000378:metabolism / Q000494:pharmacology*; D008563:Membrane Lipids / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D010316:Particle Size; D010539:Permeability; D010713:Phosphatidylcholines / Q000737:chemistry* / Q000378:metabolism; D010759:Phosphorus Isotopes; D014867:Water / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D005452:Fluoresceins; D005456:Fluorescent Dyes; D008081:Liposomes; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010759:Phosphorus Isotopes; D014867:Water; D008320:Maltose; C007740:fluorexon