Orientational changes and impaired internalization of ellipsoidal nanoparticles by vesicle membranes

Wrapping and internalization of nanoparticles by biomembranes play a critical role in drug delivery applications and nanomedicine. We study the wrapping process of a vesicle membrane around spherical and ellipsoidal nanoparticles via minimization of the bending and adhesion energies. We report two distinct regimes of spreading and internalization separated by an energy barrier and relate the success or failure of the internalization to the particle shape and wrapping orientation. We predict more difficult internalization for ellipsoidal particles with higher aspect ratios. Wrapping of ellipsoidal particles is associated with an orientational change of the particle. While the spreading starts on the flat side of the ellipsoidal particle, the particle changes its orientation during wrapping and the internalization is achieved in the tip orientation of both prolate and oblate ellipsoidal particles.