Dynamics of Microsphere Inclusions within Biomimetic Membranes Reveal Membrane Heterogeneity.

Area of Science:

• Soft matter physics
• Biophysics
• Colloid science

Background:

• Imaging nanoscale particle-membrane interactions in real-time is challenging.
• Extracellular macromolecules and particles interact with cell membranes via endocytosis, exocytosis, and drug uptake.

Purpose of the Study:

• To investigate particle dynamics and interactions at colloidal membrane surfaces.
• To understand the mechanisms of particle trapping at membrane edges.
• To quantify interfacial viscosity using a scaled-up model system.

Main Methods:

• Utilized a model system of polystyrene microspheres and colloidal membranes made of rod-shaped viruses.
• Employed depletion attraction for particle-membrane binding.
• Analyzed particle motion using microscopy and quantitative analysis.

Main Results:

• Microspheres caused local membrane deformation and diffused freely in the membrane bulk.
• Particles were observed to be radially trapped near the membrane edge.
• Identified critical particle size and membrane composition for edge trapping.
• Determined local membrane interfacial viscosity from particle motion analysis.

Conclusions:

• The interplay between membrane fluctuations and particle properties dictates complex particle-membrane interaction phenomenology.
• This simplified model system provides valuable insights into biological transport processes.
• Demonstrated a method for measuring interfacial viscosity in colloidal membranes.