Influence of thermally-driven surface undulations on tethers formed from bilayer membranes
Emily Glassinger 1 and Robert M. Raphael 1*
1 Rice University
* To whom correspondence should be addressed. E-mail: rraphael{at}rice.edu.
Submitted on June 9, 2005
Revised on August 2, 2005
Accepted on 5 April 2006
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Abstract |
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Tether formation is a powerful method to study the mechanical properties of soft lipid membranes. The force required to maintain a tether at a given length depends upon both membrane elastic properties and tension. In this report, we develop a theoretical analysis that considers the contribution of thermally-driven surface undulations and the corresponding entropically-driven tensions on the conformation of tethers formed from unaspirated lipid vesicles. In this model, thermal undulations of the vesicle surface provide the excess area required for tether formation. Energy minimization demonstrates the dependence of equilibrium tether conformation on membrane tension and provides an analytical relationship between tether force and radius. If the contributions of non-local bending are not considered, an analytical relationship between tether force and length can also be obtained. The predictions of the model are compared to recently reported experimental data and a value for the initial vesicle tension is obtained. Since most analyses of tether formation from cells and unaspirated vesicles neglect the contributions of non-local bending, the appropriateness of this assumption is analyzed.
Key Words:
Membranes, Tethers, Undulations
