Surface viscosity measurements from large bilayer vesicle tether formation. I. Analysis

Area of Science:

• Biophysics
• Materials Science

Background:

• Large phospholipid vesicles can form tethers.
• Understanding bilayer surface viscosity is crucial for vesicle mechanics.

Purpose of the Study:

• To analyze tether formation in phospholipid vesicles.
• To determine the surface viscosity of the bilayer using continuum mechanics.
• To relate tether growth to experimentally measurable parameters.

Main Methods:

• Continuum mechanical approach applied to vesicle tethers.
• Membrane modeled as a 2D isotropic material with constant area deformation.
• Stoke's drag equation used to estimate force magnitude.

Main Results:

• A critical force is necessary for tether length increase.
• A dimensionless tether growth parameter was defined.
• The relationship between applied force and critical force is independent of vesicle and tether size.

Conclusions:

• Surface viscosity can be calculated from force, critical force, and tether growth rate.
• The study provides a method to experimentally measure bilayer surface viscosity.
• This analysis offers insights into the mechanical properties of lipid bilayers.