Extraction of membrane microviscosity from translational and rotational diffusion coefficients

Area of Science:

• Fluid dynamics
• Physical chemistry

Background:

• Saffman's model describes membrane-bound particle diffusion.
• Understanding particle hydrodynamics is crucial for membrane studies.

Purpose of the Study:

• To compute Stokes drag for cylindrical particles in Saffman's membrane model.
• To analyze the implications for microviscosity and bathing viscosity measurements.

Main Methods:

• Exact calculation of Stokes drag.
• Simultaneous prediction of lateral and rotational diffusion coefficients.

Main Results:

• The study provides precise Stokes drag values.
• Calculated diffusion coefficients challenge previous microviscosity estimates.

Conclusions:

• Microviscosities in membrane environments may be lower than previously assumed.
• Bathing fluid viscosities play a significant role in particle diffusion.