Wrapping of ellipsoidal nano-particles by fluid membranes

TL;DR

This study models how ellipsoidal nano-particles are wrapped by fluid membranes, revealing unique partially-wrapped states and implications for viral uptake and virulence.

Contribution

It introduces a numerical framework to analyze membrane wrapping of ellipsoidal particles, highlighting differences from spherical particles and biological implications.

Findings

Partially-wrapped states occur at zero tension for ellipsoids.

Ellipsoids show long-lived partially-wrapped states due to curvature.

Ellipsoidal particles may have lower cellular uptake rates.

Abstract

Membrane budding and wrapping of particles, such as viruses and nano-particles, play a key role in intracellular transport and have been studied for a variety of biological and soft matter systems. We study nano-particle wrapping by numerical minimization of bending, surface tension, and adhesion energies. We calculate deformation and adhesion energies as a function of membrane elastic parameters and adhesion strength to obtain wrapping diagrams. We predict unwrapped, partially-wrapped, and completely-wrapped states for prolate and oblate ellipsoids for various aspect ratios and particle sizes. In contrast to spherical particles, where partially-wrapped states exist only for finite surface tensions, partially-wrapped states for ellipsoids occur already for tensionless membranes. In addition, the partially-wrapped states are long-lived, because of an increased energy cost for wrapping of the highly-curved tips. Our results suggest a lower uptake rate of ellipsoidal particles by cells and thereby a higher virulence of tubular viruses compared with icosahedral viruses, as well as co-operative budding of ellipsoidal particles on membranes.