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Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy
Published on: August 13, 2019
Interfacial water structure associated with phospholipid membranes studied by phase-sensitive vibrational sum
Xiangke Chen1, Wei Hua, Zishuai Huang
1Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
Journal of the American Chemical Society
|August 12, 2010
Summary
Interfacial water molecules align with phospholipid tails, with net-negative lipids causing stronger water ordering. Calcium binding to lipids disrupts this water ordering at the interface.
Area of Science:
- Physical Chemistry
- Biophysics
- Surface Science
Background:
- Understanding interfacial water structure is crucial for biological processes.
- Phospholipids form cell membranes, and their interaction with water influences membrane function.
Purpose of the Study:
- To investigate the orientation and ordering of water molecules at various phospholipid/water interfaces.
- To compare the water-structuring capabilities of different phospholipid headgroups.
Main Methods:
- Phase-sensitive vibrational sum frequency generation (SFG) spectroscopy was used.
- The study examined interfaces formed by dipalmitoyl phosphocholine (DPPC), dipalmitoyl phosphoethanolamine (DPPE), dipalmitoyl phosphate (DPPA), dipalmitoyl phosphoglycerol (DPPG), and dipalmitoyl phospho-l-serine (DPPS).
Main Results:
- Interfacial water molecules consistently orient with their dipoles pointing towards phospholipid tails across all studied lipids.
- Zwitterionic phospholipids (DPPC, DPPE) exhibited weaker water-orienting effects compared to net-negative phospholipids (DPPA, DPPG, DPPS).
- The presence of calcium cations bound to the lipid phosphate group was found to decrease the ordering of interfacial water molecules.
Conclusions:
- The electrostatic potential of phospholipid headgroups significantly dictates interfacial water structure.
- Lipid headgroup charge influences the degree of water ordering, with net-negative charges promoting greater order.
- Cation binding can modulate the hydration layer at phospholipid interfaces, impacting molecular interactions.
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