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Updated: Jun 14, 2026

Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy
Published on: October 24, 2017
On the surface tension of fluctuating quasi-spherical vesicles
C Barbetta1, A Imparato, J-B Fournier
1Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS and Université Paris Diderot-Paris 7, Bât. Condorcet, CC 7056, 75205, Paris, France. camilla.barbetta@m4x.org
Abstract:
We calculate the stress tensor for a quasi-spherical vesicle and we thermally average it in order to obtain the actual, mechanical, surface tension tau of the vesicle. Both closed and poked vesicles are considered. We recover our results for tau by differentiating the free energy with respect to the proper projected area. We show that tau may become negative well before the transition to oblate shapes and that it may reach quite large negative values in the case of small vesicles. This implies that spherical vesicles may have an inner pressure lower than the outer one.
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