Surface viscosity measurements from large bilayer vesicle tether formation. II. Experiments

Area of Science:

• Biophysics
• Materials Science
• Membrane Biophysics

Background:

• Lipid bilayer membranes are crucial biological structures with complex mechanical properties.
• Understanding membrane viscosity is essential for comprehending cellular processes and membrane dynamics.
• Previous methods for measuring membrane viscosity have limitations.

Purpose of the Study:

• To develop and validate a novel mechanical experiment for determining the upper bound of lipid bilayer membrane viscosity.
• To establish a method for calculating surface viscosity from experimental data.
• To compare these findings with existing measurements of membrane viscosity.

Main Methods:

• Formation of membrane tethers from phospholipid vesicles using fluid drag from a micropipette.
• Measurement of tether formation rate as a function of suspending fluid velocity.
• Application of a theoretical model to calculate surface viscosity from the tether formation data.

Main Results:

• Successfully developed a mechanical experiment to measure lipid bilayer membrane viscosity.
• Obtained an upper bound for membrane surface viscosity in the range of 5.0-13.0 x 10(-6) dyn s/cm.
• Experimental results show good agreement with values derived from lateral and rotational mobility measurements.

Conclusions:

• The developed mechanical method provides a reliable upper bound for lipid bilayer membrane viscosity.
• The findings contribute to a better understanding of the mechanical properties of cell membranes.
• This technique offers a valuable tool for future investigations into membrane biophysics.