title: Effect of lanthanide ions on the phase behavior of dipalmitoylphosphatidylcholine multilamellar liposomes.
abstract: The effect of lanthanide ions (Ln3+) and their coordination compounds of diethylenetriamine pentaacetic acid (DTPA) on the phase behavior of dipalmitoylphosphatidylcholine (DPPC) multi-lamellar liposomes has been studied by differential scanning calorimetry (DSC), Raman spectroscopy, and freeze-fracture electron microscopic techniques. The displacement of Ca2+ binding on DPPC liposomes by lanthanide ions was also studied. The results show that the binding degree of four kinds of chloride salts with DPPC liposomes is: YbCl3 > GdCl3 > LaCl3 > CaCl2. Lanthanide ions increase the phase transition temperature of DPPC liposomes and decrease the membrane fluidity. Freeze-fracture electron microscopic results show that La3+ enhances the order of DPPC membrane. The effect of coordination compounds of lanthanides with DTPA on the phase behavior of DPPC liposomes is smaller than that of their chlorides. La3+, Gd3+, and Yb3+, can displace Ca2+ binding on DPPC liposomes, but there coordination compounds of DTPA can hardly displace Ca2+. Raman spectroscopic results show that a very slight effect in lateral packing order of DPPC liposomes was observed at various concentrations of lanthanides.
authors.affiliation: Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Academia Sinica, P. R. China.
authors.forename: X M
authors.initials: XM
authors.lastname: Li
authors.forename: Y F
authors.initials: YF
authors.lastname: Zhang
authors.forename: J Z
authors.initials: JZ
authors.lastname: Ni
authors.forename: J W
authors.initials: JW
authors.lastname: Chen
authors.forename: F
authors.initials: F
authors.lastname: Hwang
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry* / Q000378:metabolism; D001667:Binding, Competitive; D002118:Calcium / Q000378:metabolism; D002152:Calorimetry, Differential Scanning; D002412:Cations; D005614:Freeze Fracturing; D005682:Gadolinium / Q000378:metabolism / Q000494:pharmacology; D007811:Lanthanum / Q000378:metabolism / Q000494:pharmacology; D008081:Liposomes / Q000737:chemistry* / Q000378:metabolism; D008674:Metals, Rare Earth / Q000378:metabolism / Q000494:pharmacology*; D008854:Microscopy, Electron; D004369:Pentetic Acid / Q000494:pharmacology; D013059:Spectrum Analysis, Raman; D015018:Ytterbium / Q000378:metabolism / Q000494:pharmacology
chemical_list: D002412:Cations; D008081:Liposomes; D008674:Metals, Rare Earth; D015060:1,2-Dipalmitoylphosphatidylcholine; D007811:Lanthanum; D004369:Pentetic Acid; D005682:Gadolinium; D015018:Ytterbium; D002118:Calcium