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Vesicle Origami and the Influence of Cholesterol on Lipid Packing

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Tanasescu Radu, Lanz Martin A., Mueller Dennis, Tassler Stephanie, Ishikawa Takashi, Reiter Renate, Brezesinski Gerald, Zumbuehl Andreas,
Project Exploring Stable Phospholipid Membranes
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Original article (peer-reviewed)

Journal Langmuir
Volume (Issue) 32(19)
Page(s) 4896 - 4903
Title of proceedings Langmuir
DOI 10.1021/acs.langmuir.6b01143


© 2016 American Chemical Society. The artificial phospholipid Pad-PC-Pad was analyzed in 2D (monolayers at the air/water interface) and 3D (aqueous lipid dispersions) systems. In the gel phase, the two leaflets of a Pad-PC-Pad bilayer interdigitate completely, and the hydrophobic bilayer region has a thickness comparable to the length of a single phospholipid acyl chain. This leads to a stiff membrane with no spontaneous curvature. Forced into a vesicular structure, Pad-PC-Pad has faceted geometry, and in its extreme form, tetrahedral vesicles were found as predicted a decade ago. Above the main transition temperature, a noninterdigitated L α phase with fluid chains has been observed. The addition of cholesterol leads to a slight decrease of the main transition temperature and a gradual decrease in the transition enthalpy until the transition vanishes at 40 mol % cholesterol in the mixture. Additionally, cholesterol pulls the chains apart, and a noninterdigitated gel phase is observed. In monolayers, cholesterol has an ordering effect on liquid-expanded phases and disorders condensed phases. The wavenumbers of the methylene stretching vibration indicate the formation of a liquid-ordered phase in mixtures with 40 mol % cholesterol.