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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 LU and Kuster, Simon (2018) In Journal of Visualized Experiments 2018(131).
Abstract

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+... (More)

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.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Bicelles, Birefringence, Engineering, Issue 131, Lanthanide ions, Magnetic alignment, Phospholipids, Polymolecular assemblies, Soft materials
in
Journal of Visualized Experiments
volume
2018
issue
131
publisher
JoVE
external identifiers
  • scopus:85041132671
ISSN
1940-087X
DOI
10.3791/56812
language
English
LU publication?
yes
id
3fa5e26b-cfc2-4f24-96dc-26a7b2f7d902
date added to LUP
2018-03-09 13:45:15
date last changed
2018-05-29 11:54:36
@article{3fa5e26b-cfc2-4f24-96dc-26a7b2f7d902,
  abstract     = {<p>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 (Ln<sup>3+</sup>) 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/Ln<sup>3+</sup> (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 Ln<sup>3+</sup> 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.</p>},
  articleno    = {e56812},
  author       = {Isabettini, Stéphane and Baumgartner, Mirjam E. and Fischer, Peter and Windhab, Erich J. and Liebi, Marianne and Kuster, Simon},
  issn         = {1940-087X},
  keyword      = {Bicelles,Birefringence,Engineering,Issue 131,Lanthanide ions,Magnetic alignment,Phospholipids,Polymolecular assemblies,Soft materials},
  language     = {eng},
  month        = {01},
  number       = {131},
  publisher    = {JoVE},
  series       = {Journal of Visualized Experiments},
  title        = {Fabrication procedures and birefringence measurements for designing magnetically responsive lanthanide ion chelating phospholipid assemblies},
  url          = {http://dx.doi.org/10.3791/56812},
  volume       = {2018},
  year         = {2018},
}