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Updated: Mar 8, 2026

Temperature-Controlled Assembly and Characterization of a Droplet Interface Bilayer
Published on: April 19, 2021
Dynamical Transitions at Low Temperatures in the Nearest Hydration Shell of Phospholipid Bilayers
V N Syryamina1,2, S A Dzuba1,2
1Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences , Novosibirsk 630090, Russian Federation.
Hydration water is crucial for biological system dynamics. Electron spin echo envelope modulation (ESEEM) spectroscopy reveals water molecule dynamics in lipid bilayers, uncovering transitions linked to lipid chain flexibility and water motion.
Area of Science:
- Biophysics
- Membrane Biophysics
- Spectroscopy
Background:
- Hydration water plays a key role in the transition from harmonic to anharmonic motions in biological systems.
- Understanding molecular motions within the hydration shell is essential for elucidating the mechanisms of these dynamical transitions.
- Model biological membranes provide a simplified system to study complex hydration dynamics.
Purpose of the Study:
- To investigate the molecular motions in the nearest hydration shell of spin-labeled model biological membranes.
- To correlate hydration water dynamics with lipid chain dynamics and overall membrane transitions.
- To compare hydration dynamics in unsaturated (POPC) versus saturated (DPPC) lipid bilayers.
Main Methods:
- Utilized pulsed electron paramagnetic resonance, specifically electron spin echo envelope modulation (ESEEM) spectroscopy.
- Employed deuterium (2H) water for hydration, allowing 2H ESEEM spectra analysis.
- Compared spectra from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers.
Main Results:
- 2H ESEEM spectra exhibited NMR-like line shapes, sensitive to molecular motion.
- A sharp spectral narrowing was observed between 180-190 K for both POPC and DPPC bilayers, indicating a dynamical transition.
- An inflection in spin relaxation at 188 K correlated with the onset of isotropic water molecular dynamics (∼105 s-1) in the hydration shell.
- POPC bilayers showed additional spectral changes above 100 K, linked to restricted water motion and excessive lipid chain flexibility.
Conclusions:
- The dynamical transition in lipid bilayers is accompanied by the onset of isotropic water dynamics in the nearest hydration shell.
- Distinct dynamical transitions occur at different temperatures, influenced by lipid unsaturation and chain packing.
- ESEEM spectroscopy is a powerful tool for studying hydration water dynamics and its interplay with membrane lipid behavior.
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