Polymer-Induced Swelling of Solid-Supported Lipid Membranes

Area of Science:

• Materials Science
• Biophysics
• Polymer Science

Background:

• Solid-supported lipid bilayers are crucial models for cell membranes.
• Understanding polymer-membrane interactions is key to biomimetic applications.

Purpose of the Study:

• To investigate the interaction between charged polymers and supported lipid membranes.
• To quantify the swelling effect induced by poly(allylamine hydrochloride) (PAH).

Main Methods:

• In-situ neutron reflectivity was employed to study the swelling of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membranes.
• Experiments were conducted using poly(allylamine hydrochloride) (PAH) in D₂O solutions.

Main Results:

• Poly(allylamine hydrochloride) (PAH) induced significant swelling of DMPC lipid bilayers, increasing d-spacing by approximately fourfold.
• Temperature, time, and pH were found to influence the swollen lipid layers.
• The DMPC membrane stacks remained attached to the support even above the lipid phase transition temperature (Tm).

Conclusions:

• Electrostatic interactions between PAH and lipid bilayers are the primary drivers of the observed swelling.
• Steric interactions from adsorbed PAH contribute to the stabilization of the swollen membranes.
• This system provides a platform for studying biomembrane properties with preserved fluidity and freedom.