Phase separation of lipid species is believed to underlie formation of lipid rafts that enable the concentration of certain surface receptors. However, the dynamics and stabilization of the resulting surface domains are unclear. We developed a methodology for collapsing giant unilamellar vesicles (GUVs) into supported bilayers in a way that keeps membrane nanodomains stable and enables their imaging. We used a combination of fluorescence and atomic force microscopy (AFM) of this system to uncover how a surprising phase separation occurs on lipid vesicles, in which two different gel phases of the same lipid co-exist. This unusual phase behavior was evident in binary GUVs containing 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) and either 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC). The approach showed that one of the phases is stabilized by lipid patches that become ejected from the membrane, thereby enabling the stabilization of what would otherwise be a thermodynamically impossible coexistence. These results show the utility of AFM on collapsed GUVs, and suggest a possible mechanical mechanism for stabilization of lipid domains.
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July 2019
Research-Article
Atomic Force Microscopy of Phase Separation on Ruptured, Giant Unilamellar Vesicles, and a Mechanical Pathway for the Co-Existence of Lipid Gel Phases
Yanfei Jiang,
Yanfei Jiang
Department of Biochemistry and
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
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Kenneth M. Pryse,
Kenneth M. Pryse
Department of Mechanical Engineering
and Materials Science,
Washington University,
St. Louis, MO 63110
and Materials Science,
Washington University,
St. Louis, MO 63110
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Srikanth Singamaneni,
Srikanth Singamaneni
Department of Mechanical Engineering
and Materials Science,
Washington University,
St. Louis, MO 63110
and Materials Science,
Washington University,
St. Louis, MO 63110
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Guy M. Genin,
Guy M. Genin
Department of Mechanical Engineering
and Materials Science,
Washington University,
St. Louis, MO 63110;
and Materials Science,
Washington University,
St. Louis, MO 63110;
NSF Science and Technology,
Center for Engineering Mechanobiology,
Washington University,
St. Louis, MO 63110
e-mail: genin@wustl.edu
Center for Engineering Mechanobiology,
Washington University,
St. Louis, MO 63110
e-mail: genin@wustl.edu
1Corresponding authors.
Search for other works by this author on:
Elliot L. Elson
Elliot L. Elson
Department of Biochemistry and
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
e-mail: elson@wustl.edu
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
e-mail: elson@wustl.edu
1Corresponding authors.
Search for other works by this author on:
Yanfei Jiang
Department of Biochemistry and
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
Kenneth M. Pryse
Department of Mechanical Engineering
and Materials Science,
Washington University,
St. Louis, MO 63110
and Materials Science,
Washington University,
St. Louis, MO 63110
Srikanth Singamaneni
Department of Mechanical Engineering
and Materials Science,
Washington University,
St. Louis, MO 63110
and Materials Science,
Washington University,
St. Louis, MO 63110
Guy M. Genin
Department of Mechanical Engineering
and Materials Science,
Washington University,
St. Louis, MO 63110;
and Materials Science,
Washington University,
St. Louis, MO 63110;
NSF Science and Technology,
Center for Engineering Mechanobiology,
Washington University,
St. Louis, MO 63110
e-mail: genin@wustl.edu
Center for Engineering Mechanobiology,
Washington University,
St. Louis, MO 63110
e-mail: genin@wustl.edu
Elliot L. Elson
Department of Biochemistry and
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
e-mail: elson@wustl.edu
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
e-mail: elson@wustl.edu
1Corresponding authors.
Manuscript received December 10, 2018; final manuscript received May 26, 2019; published online June 13, 2019. Assoc. Editor: Victor H. Barocas.
J Biomech Eng. Jul 2019, 141(7): 071003 (7 pages)
Published Online: June 13, 2019
Article history
Received:
December 10, 2018
Revised:
May 26, 2019
Citation
Jiang, Y., Pryse, K. M., Singamaneni, S., Genin, G. M., and Elson, E. L. (June 13, 2019). "Atomic Force Microscopy of Phase Separation on Ruptured, Giant Unilamellar Vesicles, and a Mechanical Pathway for the Co-Existence of Lipid Gel Phases." ASME. J Biomech Eng. July 2019; 141(7): 071003. https://doi.org/10.1115/1.4043871
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