期刊
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES
卷 1788, 期 10, 页码 2142-2149出版社
ELSEVIER
DOI: 10.1016/j.bbamem.2009.08.006
关键词
Lipid domain; Giant unilamellar vesicle; Equilibrium thermodynamic phase; Confocal fluorescence microscopy; Lever rule; 3D reconstruction
资金
- Forskningsradet for Natur og Univers (FNU, Denmark)
- Forskningsradet for Sundhed og Sygdom (FSS)
- Danish National Research Foundation
- FONDECYT [1060890, 1090246, 7060265, 7080031]
- FONDEF [D0711019]
- CONICYT (Chile)
- Millennium Scientific Initiative [ICM P04-068-F]
- MEMPHYS, Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark
We report a novel analytical procedure to measure the surface areas of coexisting lipid domains in giant unilamellar vesicles (GUVs) based on image processing of 3D fluorescence microscopy data. The procedure involves the segmentation of lipid domains from fluorescent image stacks and reconstruction of 3D domain morphology using active surface models. This method permits the reconstruction of the spherical surface of GUVs and determination of the area fractions of coexisting lipid domains at the level of single vesicles. Obtaining area fractions enables the scrutiny of the [ever rule along lipid phase diagram's tie lines and to test whether or not the coexistence of lipid domains in GUVs correspond to equilibrium thermodynamic phases. The analysis was applied to DLPC/DPPC GUVs displaying coexistence of lipid domains. Our results confirm the lever rule, demonstrating that the observed membrane domains correspond to equilibrium thermodynamic phases (i.e., solid ordered and liquid disordered phases). In addition, the fact that the lever rule is validated from 11 to 14 randomly selected GUVs per molar fraction indicates homogeneity in the lipid composition among the explored GUV populations. In conclusion, our study shows that GUVs are reliable model systems to perform equilibrium thermodynamic studies of membranes. (C) 2009 Elsevier B.V. All rights reserved.
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