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Raman Spectroscopic Study of Phase Coexistence in Binary Phospholipid Bilayers
Sergey V Adichtchev1, Konstantin A Okotrub1, Alexey M Pugachev1
1Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk, Russia.
Applied Spectroscopy
|July 15, 2020
Summary
Researchers developed a label-free method using Raman spectroscopy to detect lipid phase separation in phospholipid bilayers. This technique identifies coexisting ordered and disordered lipid phases, crucial for understanding membrane behavior.
Area of Science:
- Biophysics
- Materials Science
- Spectroscopy
Background:
- Phospholipid bilayers are fundamental to cell membranes.
- Understanding lipid phase behavior is key to membrane function.
- Phase separation influences membrane properties and interactions.
Purpose of the Study:
- To investigate lipid phase coexistence in binary phospholipid bilayers.
- To identify sensitive Raman spectral features indicating phase separation.
- To develop a label-free method for detecting lipid phase transitions.
Main Methods:
- Raman spectroscopy was employed to analyze phospholipid bilayers.
- Differential Scanning Calorimetry (DSC) was used for validation.
- Analysis focused on specific Raman line features (e.g., 2850 cm⁻¹, 1300 cm⁻¹) sensitive to lipid conformation.
Main Results:
- The low-frequency half-width of half-maximum (LHWHM) of the 2850 cm⁻¹ Raman line clearly indicated coexisting lipid phases.
- Phase coexistence was observed in 1,2-palmitoyl-sn-glycero-3-phosphocholine (DPPC) mole concentrations from 0.4 to 0.9.
- Raman spectral shape at 1300 cm⁻¹ also served as an indicator for phase state and coexistence.
- DSC confirmed two phase transition peaks, independent of DPPC concentration, in the observed range.
Conclusions:
- Raman spectroscopy provides a robust, label-free method for detecting lipid phase separation.
- The technique offers micrometer resolution for analyzing phase coexistence in phospholipid bilayers.
- This approach is valuable for studying membrane heterogeneity and dynamics.
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