title: Cholesterol-diethylenetriaminepentaacetate complexed with thulium ions integrated into bicelles to increase their magnetic alignability.
abstract: Lanthanides have been used for several decades to increase the magnetic alignability of bicelles. DMPE-DTPA (1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylenetriaminepentaacetate) is commonly applied to anchor the lanthanides into the bicelles. However, because DMPE-DTPA has the tendency to accumulate at the highly curved edge region of the bicelles and if located there does not contribute to the magnetic orientation energy, we have tested cholesterol-DTPA complexed with thulium ions (Tm(3+)) as an alternative chelator to increase the magnetic alignability. Differential scanning calorimetric (DSC) measurements indicate the successful integration of cholesterol-DTPA into a DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) bilayer. Cryo transmission electron microscopy and small-angle neutron scattering (SANS) measurements show that the disklike structure, that is, bicelles, is maintained if cholesterol-DTPA·Tm(3+) is integrated into a mixture of DMPC, cholesterol, and DMPE-DTPA·Tm(3+). The size of the bicelles is increased compared to the size of the bicelles obtained from mixtures without cholesterol-DTPA·Tm(3+). Magnetic-field-induced birefringence and SANS measurements in a magnetic field show that with addition of cholesterol-DTPA·Tm(3+) the magnetic alignability of these bicelles is significantly increased compared to bicelles composed of DMPC, cholesterol, and DMPE-DTPA·Tm(3+) only.
authors.affiliation: Laboratory of Food Process Engineering, ETH Zurich , Schmelzbergstrasse 9, 8092 Zurich, Switzerland.
authors.forename: Marianne
authors.initials: M
authors.lastname: Liebi
authors.forename: Simon
authors.initials: S
authors.lastname: Kuster
authors.forename: Joachim
authors.initials: J
authors.lastname: Kohlbrecher
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Peter
authors.initials: P
authors.lastname: Fischer
authors.forename: Peter
authors.initials: P
authors.lastname: Walde
authors.forename: Erich J
authors.initials: EJ
authors.lastname: Windhab
mesh_terms: D001718:Birefringence; D002614:Chelating Agents / Q000737:chemistry; D002784:Cholesterol / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D020285:Cryoelectron Microscopy; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D060328:Magnetic Phenomena; D008280:Magnetics; D033363:Neutron Diffraction; D004369:Pentetic Acid / Q000737:chemistry*; D053838:Scattering, Small Angle; D013932:Thulium / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D056831:Coordination Complexes; D008051:Lipid Bilayers; D004369:Pentetic Acid; D013932:Thulium; D002784:Cholesterol; D004134:Dimyristoylphosphatidylcholine