Single plasmonic nanoparticle tracking studies of solid supported bilayers with ganglioside lipids

Area of Science:

• Biophysics
• Materials Science
• Surface Chemistry

Background:

• Solid supported lipid bilayers (SLBs) are crucial models for cell membrane studies.
• Gangliosides (GM(1)) are important membrane components influencing lipid bilayer dynamics.
• Understanding diffusion in lipid bilayers is key to cellular processes.

Purpose of the Study:

• To investigate the effect of ganglioside (GM(1)) concentration on nanoparticle diffusion in SLBs.
• To determine the percolation threshold of GM(1) in the lipid bilayer system.
• To analyze the relationship between GM(1) concentration and diffusion characteristics.

Main Methods:

• Single-particle tracking of gold nanoparticles in SLBs with varying GM(1) concentrations.
• Electrostatic association of negatively charged nanoparticles with positively charged lipids (ethyl phosphatidylcholine).
• Analysis of diffusion patterns (random vs. confined) and root-mean-squared displacement (RMSD).

Main Results:

• At 0% GM(1), 92% of particles exhibited random diffusion (D = 4.3 × 10⁻⁹ cm²/s).
• At 14% GM(1), 62% of particles showed confined diffusion, indicating GM(1) clusters restrict movement.
• A decreasing trend in diffusion constant and confining diameter with increasing GM(1) was observed.

Conclusions:

• Nanoparticle confinement is mediated by GM(1) clusters, not direct association.
• The percolation threshold for this SLB system was determined to be 22% GM(1).
• The confining diameter at the percolation threshold was approximately 50 nm.