Cholesterol-Diethylenetriaminepentaacetate Complexed with Thulium Ions Integrated into Bicelles To Increase Their Magnetic Alignability

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• 作者：Marianne Liebi ; Simon Kuster ; Joachim Kohlbrecher ; Takashi Ishikawa ; Peter Fischer ; Peter Walde ; Erich J. Windhab
• 刊名：Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：November 27, 2013
• 年：2013
• 卷：117
• 期：47
• 页码：14743-14748
• 全文大小：310K
• 年卷期：v.117,no.47(November 27, 2013)
• ISSN：1520-5207

文摘

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 (Tm³⁺) 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路Tm³⁺ is integrated into a mixture of DMPC, cholesterol, and DMPE-DTPA路Tm³⁺. The size of the bicelles is increased compared to the size of the bicelles obtained from mixtures without cholesterol-DTPA路Tm³⁺. Magnetic-field-induced birefringence and SANS measurements in a magnetic field show that with addition of cholesterol-DTPA路Tm³⁺ the magnetic alignability of these bicelles is significantly increased compared to bicelles composed of DMPC, cholesterol, and DMPE-DTPA路Tm³⁺ only.