Liposome clusters with shear stress-induced membrane permeability
Makoto Yoshimoto1, Ryota Tamura, Tomotaka Natsume
1Department of Applied Molecular Bioscience, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan.
Chemistry and Physics of Lipids
|June 25, 2013
Summary
Negatively charged liposomes form reversible clusters with calcium ions. Under shear stress, these flexible clusters allow membrane permeation, crucial for biochemical and biomedical applications.
Area of Science:
- Biochemistry
- Materials Science
- Physical Chemistry
Background:
- Liposomes are versatile lipid-based vesicles used in drug delivery and biomimetic systems.
- Controlling liposome aggregation and membrane permeability is key for their application.
- Calcium ions (Ca2+) are known to induce aggregation in negatively charged liposomes.
Purpose of the Study:
- To investigate the formation and structural properties of Ca2+-induced liposome clusters.
- To characterize the membrane permeability of these liposome clusters under static and shear flow conditions.
- To understand the role of liposome composition and shear stress in cluster behavior.
Main Methods:
- Preparation of liposomes composed of POPC, POPG, and cholesterol.
- Induction of liposome clustering using varying Ca2+ concentrations.
- Characterization of cluster size and liposome redispersal.
- Measurement of 5(6)-carboxyfluorescein (CF) permeation across liposome membranes under static and shear flow.
- Theoretical analysis using modified DLVO potential.
Main Results:
- Reversible clustering of liposomes was achieved with specific lipid and Ca2+ concentrations.
- POPC content significantly influenced the reversibility of liposome aggregation.
- Liposome clusters were impermeable to CF in static conditions due to reduced surface area.
- Under shear stress (1.5 × 10^3 s^-1), CF permeation was observed, similar to non-clustered liposomes.
- Theoretical analysis confirmed structural flexibility of clusters under shear, maintaining membrane-water interface.
Conclusions:
- Ca2+-induced liposome clustering is reversible and dependent on lipid composition, particularly POPC.
- Structurally flexible liposome clusters under shear stress facilitate membrane permeation.
- These findings are vital for controlling liposome cluster formation and permeabilization in biochemical and biomedical applications.
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