Indirect interaction of colloidal particles adsorbed on smectic films

Area of Science:

• Soft matter physics
• Biophysics
• Surface science

Background:

• Colloidal particles, such as peptides and proteins, interact with lipid bilayer stacks.
• Adsorption of these particles induces elastic deformations in the lipid bilayers, disrupting their ordered smectic phase.

Purpose of the Study:

• To investigate the nature and range of interactions between adsorbed colloidal particles mediated by lipid bilayer stacks.
• To determine the factors influencing the strength and range of this substrate-mediated force.

Main Methods:

• Theoretical modeling of elastic deformations and their superposition.
• Analysis of the resulting effective pair potential between adsorbed particles.

Main Results:

• Two adsorbed particles attract each other due to the superposition of their deformation fields.
• The effective pair potential decays exponentially with particle distance, with a range proportional to the square root of the stack thickness.
• This substrate-mediated interaction can overcome entropic barriers for aggregation on sufficiently thick stacks.

Conclusions:

• Lipid bilayer stacks mediate attractive forces between adsorbed colloidal particles.
• The thickness of the lipid stack is a critical parameter controlling the range and strength of this interaction.
• Sufficiently thick lipid stacks can promote particle aggregation or crystallization due to this substrate-mediated attraction.