Lipid bilayers cushioned with polyelectrolyte-based films on doped silicon surfaces

Area of Science:

• Materials Science
• Surface Chemistry
• Biophysics

Background:

• Silicon semiconductors are foundational for electronics.
• Surface modification is key to creating functional interfaces.
• Polyelectrolyte multilayers and lipid bilayers are vital in biosensing and nanotechnology.

Purpose of the Study:

• To investigate the adsorption and fusion of lipid vesicles on polyelectrolyte-modified silicon surfaces.
• To understand the role of lipid vesicle charge and surface charge in bilayer formation.
• To explore the potential for creating robust lipid bilayers on semiconductor substrates.

Main Methods:

• Layer-by-layer deposition of polyelectrolytes (polyethyleneimine, polystyrene sulfonate, poly(allylamine)).
• Adsorption and fusion of lipid vesicles (DOPC, DOPS, DOTAP) onto modified surfaces.
• Characterization using optical reflectometry, electrochemical impedance spectroscopy, and fluorescent recovery after photobleaching.

Main Results:

• Lipid vesicles fused to form stable lipid bilayers (>100 kΩ resistance) only on oppositely charged polyelectrolyte surfaces (e.g., DOPC/DOPS on poly(allylamine)).
• Vesicle surface charge directly correlated with adsorbed mass, as shown by optical reflectometry.
• Zwitterionic DOPC vesicles adsorbed to both positive and negative surfaces; bilayer formation occurred on negative surfaces, while intact vesicle adsorption was seen on positive surfaces.

Conclusions:

• The surface charge of lipid vesicles and the underlying polyelectrolyte layer critically determine adsorption versus fusion.
• Stable, functional lipid bilayers can be formed on silicon/silica surfaces through controlled electrostatic interactions.
• This method offers a versatile platform for fabricating biosensor interfaces and studying membrane biophysics.