High Resistivity Lipid Bilayers Assembled on Polyelectrolyte Multilayer Cushions: An Impedance Study

Area of Science:

• Biophysics
• Materials Science
• Membrane Biophysics

Background:

• Cell membranes are supported by polymer networks, making supported lipid bilayers on polymer cushions valuable biomembrane models.
• Polyelectrolyte multilayers (PEMs) offer tunable platforms for constructing supported lipid bilayers.

Purpose of the Study:

• To create and characterize lipid bilayers on polyelectrolyte multilayer (PEM) cushions.
• To investigate the electrical properties of these supported lipid bilayers and compare them to natural biomembranes.

Main Methods:

• Lipid vesicles (30% DOPC, 70% DOPS) were assembled on PAH/PSS PEMs.
• Quartz Crystal Microbalance with Dissipation (QCM-D) and cryo-transmission electron microscopy (cryo-TEM) confirmed bilayer formation.
• Electrochemical Impedance Spectroscopy (EIS) was used to measure electrical properties.

Main Results:

• A continuous, dense lipid bilayer formed on the PEM, exhibiting high electrical resistance (~10^7 Ω cm^2), comparable to black lipid membranes.
• This is the first report of such high resistance values for lipid bilayers supported on PEMs.
• Subsequent polyelectrolyte assembly on the lipid bilayer significantly reduced resistance (up to 2 orders of magnitude), indicating defect/pore formation.

Conclusions:

• Supported lipid bilayers on PEMs provide a robust model system for biomembranes with tunable electrical properties.
• The high resistance achieved demonstrates the potential of PEMs for creating biomimetic membrane systems.
• Understanding the impact of polyelectrolyte interactions on bilayer integrity is crucial for designing functional membrane interfaces.