Related Experiment Video
Updated: Jul 24, 2026
10:15
Atomic Force Microscopy Imaging and Force Spectroscopy of Supported Lipid Bilayers
Published on: July 22, 2015
Spatially patterned static roughness superimposed on thermal roughness in a condensed phospholipid monolayer
1Department of Physics, University of Washington, Seattle, Washington 98195, USA.
Summary
Diffuse light scattering imaging revealed two distinct regions in phospholipid monolayers. One region showed static surface roughness, indicating a previously undetected monolayer separation.
Area of Science:
- Surface science
- Materials science
- Biophysics
Background:
- Phospholipid monolayers at air/water interfaces are model systems for cell membranes.
- Understanding monolayer structure and dynamics is crucial for membrane biophysics.
- Previous imaging techniques lacked the resolution to detect fine structural variations.
Purpose of the Study:
- To investigate the micro- and nanostructure of phospholipid monolayers using diffuse light scattering.
- To identify and characterize previously undetected phase separations or structural heterogeneities.
- To correlate scattering properties with surface pressure and molecular organization.
Main Methods:
- Diffuse light scattering imaging in reflection mode was employed.
- Experiments were conducted on L-dipalmitoyl phosphatidylcholine (DPPC) monolayers at the air/water interface.
- Scattering intensity was analyzed as a function of surface pressure.
Main Results:
- A distinct separation within the monolayer into two regions was observed, differentiated by scattering intensity.
- Chiral-shaped domains were identified within a brighter scattering region, covering about half the monolayer.
- Scattered intensity increased with surface pressure in both regions, consistent with capillary wave scattering.
- The brighter region exhibited additional scattering, indicative of a superimposed static surface roughness.
Conclusions:
- Phospholipid monolayers can exhibit complex phase behavior with distinct regions of varying surface roughness.
- Diffuse light scattering is a sensitive technique for revealing sub-monolayer structural heterogeneities.
- The findings suggest a more intricate structural organization of phospholipid monolayers than previously assumed.
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.Fatty acids tails of phospholipids can be either saturated or...
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...
01:35Asymmetric 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%...
01:30The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...