Fabrication procedures and birefringence measurements for designing magnetically responsive lanthanide ion chelating phospholipid assemblies

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Fabrication procedures and birefringence measurements for designing magnetically responsive lanthanide ion chelating phospholipid assemblies. / Isabettini, Stéphane; Baumgartner, Mirjam E.; Fischer, Peter; Windhab, Erich J.; Liebi, Marianne; Kuster, Simon.

In: Journal of Visualized Experiments, Vol. 2018, No. 131, e56812, 03.01.2018.

Research output: Contribution to journalArticle

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Isabettini, Stéphane ; Baumgartner, Mirjam E. ; Fischer, Peter ; Windhab, Erich J. ; Liebi, Marianne ; Kuster, Simon. / Fabrication procedures and birefringence measurements for designing magnetically responsive lanthanide ion chelating phospholipid assemblies. In: Journal of Visualized Experiments. 2018 ; Vol. 2018, No. 131.

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TY - JOUR

T1 - Fabrication procedures and birefringence measurements for designing magnetically responsive lanthanide ion chelating phospholipid assemblies

AU - Isabettini, Stéphane

AU - Baumgartner, Mirjam E.

AU - Fischer, Peter

AU - Windhab, Erich J.

AU - Liebi, Marianne

AU - Kuster, Simon

PY - 2018/1/3

Y1 - 2018/1/3

N2 - Bicelles are tunable disk-like polymolecular assemblies formed from a large variety of lipid mixtures. Applications range from membrane protein structural studies by nuclear magnetic resonance (NMR) to nanotechnological developments including the formation of optically active and magnetically switchable gels. Such technologies require high control of the assembly size, magnetic response and thermal resistance. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and its lanthanide ion (Ln3+) chelating phospholipid conjugate, 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA), assemble into highly magnetically responsive assemblies such as DMPC/DMPE-DTPA/Ln3+ (molar ratio 4:1:1) bicelles. Introduction of cholesterol (Chol-OH) and steroid derivatives in the bilayer results in another set of assemblies offering unique physico-chemical properties. For a given lipid composition, the magnetic alignability is proportional to the bicelle size. The complexation of Ln3+ results in unprecedented magnetic responses in terms of both magnitude and alignment direction. The thermo-reversible collapse of the disk-like structures into vesicles upon heating allows tailoring of the assemblies' dimensions by extrusion through membrane filters with defined pore sizes. The magnetically alignable bicelles are regenerated by cooling to 5 °C, resulting in assembly dimensions defined by the vesicle precursors. Herein, this fabrication procedure is explained and the magnetic alignability of the assemblies is quantified by birefringence measurements under a 5.5 T magnetic field. The birefringence signal, originating from the phospholipid bilayer, further enables monitoring of polymolecular changes occurring in the bilayer. This simple technique is complementary to NMR experiments that are commonly employed to characterize bicelles.

AB - Bicelles are tunable disk-like polymolecular assemblies formed from a large variety of lipid mixtures. Applications range from membrane protein structural studies by nuclear magnetic resonance (NMR) to nanotechnological developments including the formation of optically active and magnetically switchable gels. Such technologies require high control of the assembly size, magnetic response and thermal resistance. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and its lanthanide ion (Ln3+) chelating phospholipid conjugate, 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA), assemble into highly magnetically responsive assemblies such as DMPC/DMPE-DTPA/Ln3+ (molar ratio 4:1:1) bicelles. Introduction of cholesterol (Chol-OH) and steroid derivatives in the bilayer results in another set of assemblies offering unique physico-chemical properties. For a given lipid composition, the magnetic alignability is proportional to the bicelle size. The complexation of Ln3+ results in unprecedented magnetic responses in terms of both magnitude and alignment direction. The thermo-reversible collapse of the disk-like structures into vesicles upon heating allows tailoring of the assemblies' dimensions by extrusion through membrane filters with defined pore sizes. The magnetically alignable bicelles are regenerated by cooling to 5 °C, resulting in assembly dimensions defined by the vesicle precursors. Herein, this fabrication procedure is explained and the magnetic alignability of the assemblies is quantified by birefringence measurements under a 5.5 T magnetic field. The birefringence signal, originating from the phospholipid bilayer, further enables monitoring of polymolecular changes occurring in the bilayer. This simple technique is complementary to NMR experiments that are commonly employed to characterize bicelles.

KW - Bicelles

KW - Birefringence

KW - Engineering

KW - Issue 131

KW - Lanthanide ions

KW - Magnetic alignment

KW - Phospholipids

KW - Polymolecular assemblies

KW - Soft materials

U2 - 10.3791/56812

DO - 10.3791/56812

M3 - Article

VL - 2018

JO - Journal of Visualized Experiments

T2 - Journal of Visualized Experiments

JF - Journal of Visualized Experiments

SN - 1940-087X

IS - 131

M1 - e56812

ER -