Related Experiment Video
Updated: May 16, 2026
06:32
Reconstitution of Septin Assembly at Membranes to Study Biophysical Properties and Functions
Published on: July 28, 2022
Controlling interactions in supported bilayers from weak electrostatic repulsion to high osmotic pressure
Arnaud Hemmerle1, Linda Malaquin, Thierry Charitat
1Université de Strasbourg, Institut Charles Sadron, Unité Propre de Recherche 22, Centre National de la Recherche Scientifique, 67034 Strasbourg Cedex 2, France.
Summary
We measured lipid bilayer interactions using X-ray scattering, finding they are softer than expected due to weak electrostatic repulsion. Osmotic pressure can tune these membrane interactions for further study.
Area of Science:
- Biophysics
- Materials Science
Background:
- Understanding membrane interactions is crucial for biological and physical systems.
- Natural conditions involve fluctuations, requiring precise measurements of membrane behavior.
Purpose of the Study:
- To determine the interaction potential between two lipid bilayers under near-natural conditions.
- To investigate the influence of hydration and lipid ionization on membrane interactions.
Main Methods:
- Grazing incidence X-ray scattering was employed to measure forces between lipid bilayers.
- A model system with one adsorbed and one floating bilayer was utilized.
- Osmotic pressure was applied to tune interaction potentials.
Main Results:
- Interactions were found to be two orders of magnitude softer than in previous studies of multilayer stacks.
- Weak electrostatic repulsion, attributed to low ionized lipid fractions and fewer defects, was observed.
- Data align with Poisson-Boltzmann theory, particularly the counter-ion entropy contribution.
- Very weak entropic repulsion potentials were measured, enabling discrimination between theoretical models.
Conclusions:
- Supported lipid bilayers exhibit significantly softer interactions than previously thought.
- Electrostatic and entropic forces, particularly counter-ion effects, govern these interactions.
- Tunable interaction potentials via osmotic pressure offer new avenues for studying membrane behavior and applications.
More Related Videos
09:54Multifunctional, Micropipette-based Method for Incorporation And Stimulation of Bacterial Mechanosensitive Ion Channels in Droplet Interface Bilayers
Published on: November 19, 2015
12:18Assembly of Cell Mimicking Supported and Suspended Lipid Bilayer Models for the Study of Molecular Interactions
Published on: August 3, 2021
Related Concept Videos
03:13Intermolecular Forces
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen bonds, and dispersion...
02:40Osmosis and Osmotic Pressure of Solutions
A number of natural and synthetic materials exhibit selective permeation, meaning that only molecules or ions of a certain size, shape, polarity, charge, and so forth, are capable of passing through (permeating) the material. Biological cell membranes provide elegant examples of selective permeation in nature, while dialysis tubing used to remove metabolic wastes from blood is a more simplistic technological example. Regardless of how they may be fabricated, these materials are generally...
01:23Theory of Strong Electrolytes
The interionic forces of the strong electrolytes depend on the solvent's dielectric constant, which is the ability of a solvent to store electrical energy, based on its polarizability. and the solution's concentration. In high-dielectric solvents and in dilute solutions, weak electrostatic forces keep ions apart. However, in low-dielectric solvents or concentrated solutions, stronger interionic forces may cause ions to pair up as ionic doublets despite being fully ionized. The theory of strong...
01:26Osmotic Pressure
Osmosis is a process where solvent molecules move toward a solution through a semipermeable membrane. As the solution dilutes due to the entry of solvent, it expands. This expansion increases the hydrostatic pressure of the solution. When the hydrostatic pressure equals the osmotic pressure, osmosis stops.Osmotic pressure, denoted by Π, is the minimum pressure needed to prevent the solvent from passing into the solution by osmosis. The van 't Hoff equation calculates the osmotic pressure of an...
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...
01:30Osmosis
Osmosis is the movement of free water molecules through a semipermeable membrane. The water's concentration gradient across the membrane is inversely proportional to the solutes' concentration. Whereas diffusion transports material across membranes and within cells, osmosis transports only water across a membrane, and the membrane limits the diffusion of solutes in the water. Osmosis is a special case of diffusion.
Water, like other substances, moves from a high concentration of free water...
Water, like other substances, moves from a high concentration of free water...