Instabilities and shape variation phase transitions in tubular lipid membranes

TL;DR

This paper investigates how external parameters influence phase transitions and shape stability in tubular lipid membranes, highlighting the role of a single effective parameter and boundary conditions in membrane behavior near critical points.

Contribution

It introduces a unified control parameter for phase transitions in TLM and analyzes the effects of boundary conditions on membrane shape stability and transition types.

Findings

Identified a single effective parameter controlling phase transitions.

Determined stability intervals for cylindrical TLM shapes.

Showed boundary conditions significantly affect membrane shape and phase behavior.

Abstract

Changes of external parameters in proximity of critical point can increase thermal fluctuations of tubular lipid membrane (TLM) and result in variation of the membrane shape. The phase transitions in the system are shown to be controlled by a single effective parameter, which depends on the pressure difference between inner and outer regions of membrane and the applied stretching force. We determine an interval of the parameter values corresponding to the stability region of the cylindrical shape of TLM and investigate the behavior of the system in the vicinity of critical instabilities, where the cylindrical shape of membrane becomes unstable with respect to thermal fluctuations. The applied boundary conditions strongly influence the behavior of TLM. For example, small negative effective parameter corresponds to chiral shape of TLM only in the case of periodic boundary conditions. We also discuss other three types of phase transitions emerging in the system.