Growth and instability of a phospholipid vesicle in a bath of fatty acids

TL;DR

This study investigates how phospholipid vesicles interact with fatty acids, revealing conditions for growth, instability, and potential artificial cell reproduction, through experimental and thermodynamic modeling.

Contribution

It introduces a phase diagram and a thermodynamic model explaining vesicle growth and instability in fatty acid environments, with implications for artificial cell development.

Findings

Vesicle growth depends on size, osmotic pressure, and fatty acid concentration.

Vesicles can become unstable and fragment under certain conditions.

Stable growth enables artificial cell reproduction with cytoskeletal proteins.

Abstract

Using a microfluidic trap, we study the behavior of individual phospholipid vesicles in contact with fatty acids. We show that spontaneous fatty acids insertion inside the bilayer is controlled by the vesicle size, osmotic pressure difference across the membrane and fatty acids concentration in the external bath. Depending on these parameters, vesicles can grow spherically or become unstable and fragment into several daughter vesicles. We establish the phase diagram for vesicle growth and we derive a simple thermodynamic model that reproduces the time evolution of the vesicle volume. Finally, we show that stable growth can be achieved on an artificial cell expressing a simple set of bacterial cytoskeletal proteins, paving the way toward artificial cell reproduction.