(442e) Spindle-like Vesicle Shapes in External Fields | AIChE

(442e) Spindle-like Vesicle Shapes in External Fields

Authors 

Miksis, M., Northwestern University
Vlahovska, P. M., Brown University
A phospholipid bilayer is the main structural component of cells and internal cellular organelles. For the past two decades, researchers have used giant unilamellar vesicles (GUVs) as a popular biomimetic model to study membrane biophysics. This work focuses on the mechanical properties and deformation of GUVs which qualitatively resemble the rich dynamics of living cells in external fields (e.g., under electric potential difference across the plasma membrane). Here, the classical Helfrich bending energy model is minimized under constraints of constant area and volume and the corresponding Euler-Lagrange equations are solved numerically to yield equilibrium shapes. We investigate the parameter space of vesicle geometric properties and environmental stimuli (e.g., osmotic pressure), and report regimes where vesicle morphologies resemble spindle-like structures observed in recent experimental results of vesicles embedded in nematic liquid crystals and vesicles suspended in electrolyte solutions under strong AC electric fields. Results show that under conditions of constant bending rigidity and low excess-area, spindle-like vesicle shapes are accessible. Allowing for a spatially varying bending rigidity to simulate the effect of an external field yields similar spindle-like configurations with lower bending energy; the origin of this local variation is the subject of ongoing research.