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Conventional and gemini surfactants embedded within bilayer membranes: contrasting behavior
A A Yaroslavov1, Udalykh OYu, N S Melik-Nubarov
1Polymer Department, School of Chemistry, Lomonosov Moscow State University, Russia. yaroslav@genebee.msu.su
Chemistry (Weinheim an Der Bergstrasse, Germany)
|January 5, 2002
Summary
Conventional and gemini surfactants exhibit distinct vesicle bilayer dynamics. Cationic conventional surfactants flip-flop in liquid membranes, while gemini surfactants do not, regardless of membrane state. Surfactant hopping and polymer interactions vary with membrane fluidity.
Area of Science:
- Physical Chemistry
- Materials Science
- Biophysics
Background:
- Vesicle bilayers are fundamental structures in biological membranes and drug delivery systems.
- Understanding surfactant behavior within these bilayers is crucial for controlling membrane properties and functions.
- Conventional and gemini surfactants possess unique structural differences influencing their interactions and dynamics.
Purpose of the Study:
- To compare the membrane dynamics of conventional and gemini surfactants using laser microelectrophoresis.
- To investigate the influence of vesicle phase state (solid vs. liquid) on surfactant behavior.
- To elucidate the interactions between surfactants, lipids, and polymers within vesicle bilayers.
Main Methods:
- Laser microelectrophoresis coupled with conductance, fluorescence, and dynamic light scattering.
- Experiments involving cationic conventional and gemini surfactants with anionic phospholipids in gel and liquid crystalline vesicles.
- Studies on mixed vesicle populations, polymer-surfactant interactions, and salt-induced dissociation.
Main Results:
- Cationic conventional surfactants neutralize anionic charges differently in solid (partial) vs. liquid (complete) membranes, enabling flip-flop in liquid states.
- Cationic gemini surfactants only neutralize outer leaflet charges, indicating no flip-flop regardless of membrane phase.
- Surfactants can hop between vesicles in liquid membranes, and polymers can influence surfactant distribution, with behavior dependent on charge and membrane fluidity.
Conclusions:
- Gemini surfactants exhibit restricted flip-flop behavior compared to conventional surfactants, influenced by membrane phase state.
- Surfactant and polymer mobility within vesicle bilayers is highly dependent on membrane fluidity and electrostatic interactions.
- Laser microelectrophoresis is a powerful technique for dissecting complex surfactant and polymer dynamics in model membrane systems.