Membrane order parameters for interdigitated lipid bilayers measured via polarized total-internal-reflection
An T Ngo1, Zygmunt J Jakubek2, Zhengfang Lu2
1Measurement Science and Standards, National Research Council Canada, Ottawa, ON K1A 0R6, Canada; Department of Physics, University of Ottawa Ottawa, ON K1N 6N5, Canada.
Biochimica Et Biophysica Acta
|July 30, 2014
Summary
Ethanol induces an interdigitated phase in lipid membranes. Polarized total-internal-reflection fluorescence microscopy (pTIRFM) with Texas Red DHPE rapidly identifies this phase by observing fluorescence contrast changes, revealing a highly ordered membrane environment.
Area of Science:
- Membrane biophysics
- Lipid bilayer dynamics
- Fluorescence microscopy techniques
Background:
- Ethanol incorporation alters lipid bilayer structure, forming distinct phases.
- Understanding these ethanol-induced phases is crucial for membrane science.
- Ternary lipid mixtures exhibit multiple co-existing phases with ethanol.
Purpose of the Study:
- To measure the order parameter of the ethanol-induced interdigitated phase (LβI).
- To evaluate the utility of polarized total-internal-reflection fluorescence microscopy (pTIRFM) for identifying lipid phases.
- To characterize the membrane environment of the LβI phase.
Main Methods:
- Utilized pTIRFM with Texas Red DHPE to study lipid mixtures with ethanol.
- Analyzed fluorescence contrast reversals with polarization angle changes.
- Measured order parameters for the LβI phase and compared with other probes.
Main Results:
- pTIRFM with Texas Red DHPE showed a contrast reversal, enabling rapid LβI phase identification.
- Order parameters indicated a highly ordered membrane environment within the LβI phase.
- BODIPY-FL-PC was less effective due to probe orientation complexities.
Conclusions:
- pTIRFM using Texas Red DHPE is an effective method for identifying ethanol-induced interdigitated lipid phases.
- The LβI phase exhibits a highly ordered structure.
- This technique can advance research on alcohol and additive effects on membranes.
