title: Tailoring Bicelle Morphology and Thermal Stability with Lanthanide-Chelating Cholesterol Conjugates.
abstract: Bicelles composed of DMPC and phospholipids capable of chelating lanthanide ions, such as 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA), are highly tunable magnetically responsive soft materials. Further doping of these systems with cholesterol-DTPA conjugates complexed to a lanthanide ion considerably enhances the bicelle's size and magnetic alignability. The high value of these cholesterol conjugates for bicelle design remains largely unexplored. Herein, we examine how molecular structural alterations within the cholesterol-DTPA conjugates lead to contrasting self-assembled polymolecular aggregate structures when incorporated into DMPC/DMPE-DTPA/Tm(3+) bilayers. The nature of the linker connecting the DTPA-chelating moiety to the sterol backbone is examined by synthesizing conjugates of various linker lengths and polarities. The incorporation of these compounds within the bilayer results in polymolecular aggregate geometries of higher curvature. The increasing degrees of freedom for conformational changes conveyed to the chelator headgroup with increasing linker atomic length reduce the cholesterol-DTPA conjugate's critical packing parameter. Consequently, an inverse correlation between the number of carbon atoms in the linker and the bicelle radius is established. The introduction of polarity into the carbon chain of the linker did not cause major changes in the polymolecular aggregate architecture. Under specific conditions, the additives permit the formation of remarkably temperature-resistant bicelles. The versatility of design offered by these amphiphiles gives rise to new and viable tools for the growing field of magnetically responsive soft materials.
authors.affiliation: Laboratory of Food Process Engineering, ETH Zurich , Schmelzbergstrasse 9, 8092 Zurich, Switzerland.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Isabettini
authors.forename: Marianne
authors.initials: M
authors.lastname: Liebi
authors.forename: Joachim
authors.initials: J
authors.lastname: Kohlbrecher
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Laboratory of Food Process Engineering, ETH Zurich , Schmelzbergstrasse 9, 8092 Zurich, Switzerland.
authors.forename: Erich J
authors.initials: EJ
authors.lastname: Windhab
authors.affiliation: Laboratory of Food Process Engineering, ETH Zurich , Schmelzbergstrasse 9, 8092 Zurich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Fischer
authors.affiliation: Department of Materials, ETH Zurich , Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Walde
authors.affiliation: Laboratory of Food Process Engineering, ETH Zurich , Schmelzbergstrasse 9, 8092 Zurich, Switzerland.
authors.forename: Simon
authors.initials: S
authors.lastname: Kuster
mesh_terms: D002784:Cholesterol / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D004355:Drug Stability; D006358:Hot Temperature; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D059346:Magnets; D008823:Micelles; D004369:Pentetic Acid / Q000737:chemistry*; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D028581:Lanthanoid Series Elements; D008051:Lipid Bilayers; D008823:Micelles; D010714:Phosphatidylethanolamines; D004369:Pentetic Acid; D002784:Cholesterol; D004134:Dimyristoylphosphatidylcholine; C018525:1,2-dimyristoylphosphatidylethanolamine