Related Experiment Video
Updated: May 13, 2026
10:15
Atomic Force Microscopy Imaging and Force Spectroscopy of Supported Lipid Bilayers
Published on: July 22, 2015
Metastability in pixelation patterns of coexisting fluid lipid bilayer phases imposed by e-beam patterned substrates
Maria O Ogunyankin1, Marjorie L Longo
1Department of Chemical Engineering and Materials Science, University of California, Davis, 1 Shields avenue, Davis CA, 95616, USA.
Soft Matter
|March 14, 2013
Summary
Lipid membranes form dynamic pixilation patterns that disappear at room temperature due to high line energy. These patterns can be regenerated by cooling, suggesting fixed nucleation sites.
Area of Science:
- Membrane Biophysics
- Soft Matter Physics
- Materials Science
Background:
- Lipid multibilayers exhibit phase separation between liquid-ordered (Lo) and liquid-disordered (Ld) phases.
- Curvature of lipid membranes significantly influences phase behavior and domain formation.
Purpose of the Study:
- To investigate the dynamic evolution of pixilation patterns in phase-separating lipid multibilayers under controlled curvature.
- To understand the mechanisms governing the stability and regeneration of these patterns.
Main Methods:
- Fabrication of curvature-patterned substrates using electron beam lithography with varying feature radii and lattice spacing.
- Observation of dynamic changes in Lo phase pixilation patterns over time at room temperature.
- Analysis of kinetic rates and pattern regeneration upon temperature changes.
Main Results:
- Lo phase pixilation patterns showed a decrease in area fraction over time, approaching zero at room temperature.
- Two dominant mechanisms for pattern dissolution were identified: diffusion-limited dissolution (Ostwald ripening) and cooperative vesicle formation.
- Spontaneous tubule formation was observed in high-curvature regions.
- Pixilation patterns were successfully regenerated by cooling below room temperature, indicating stable nucleation sites.
Conclusions:
- The observed metastability of Lo phase pixilation patterns is attributed to high line energy and unfavorable equilibrium partitioning at room temperature.
- Pattern regeneration upon cooling suggests the presence of persistent nucleation sites on the patterned substrate.
- The study provides insights into the interplay between membrane curvature, phase separation, and pattern dynamics in lipid bilayers.
Related Concept Videos
01:23Membrane Fluidity
Cell membranes are composed of phospholipids, proteins, and carbohydrates loosely attached to one another through chemical interactions. Molecules are generally able to move about in the plane of the membrane, giving the membrane its flexible nature called fluidity. Two other features of the membrane contribute to membrane fluidity: the chemical structure of the phospholipids and the presence of cholesterol in the membrane.
01:26Membrane Fluidity
Membrane fluidity is explained by the fluid mosaic model of the cell membrane, which describes the plasma membrane structure as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character.
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
01:19Fluid Mosaic Model
Scientists identified the plasma membrane in the 1890s and its principal chemical components (lipids and proteins) by 1915. The model for plasma membrane structure, proposed in 1935 by Hugh Davson and James Danielli, was the first model to be widely accepted in the scientific community. The model was based on the plasma membrane's "railroad track" appearance in early electron micrographs. Davson and Danielli theorized that the plasma membrane's structure resembled a sandwich with the analogy of...
01:34The Fluid Mosaic Model
The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of membranes and serves as a foundation for future membrane-related studies. The model depicts the structure of the plasma membrane with a variety of components, which include phospholipids, proteins, and carbohydrates. These integral molecules are loosely bound, defining the cell’s border and providing fluidity for optimal function.
01:35Asymmetric Lipid Bilayer
Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. The treatment of the erythrocyte membrane with the enzyme phospholipase confirmed the asymmetric nature of the lipid bilayer. The enzyme hydrolyzes lipids into fatty acids and hydrophilic groups. The phospholipase acts only on the outer layer of the membrane, while the inner layer remains intact. The phospholipase treatment resulted in 80%...