title: Membrane-mediated aggregation of anisotropically curved nanoparticles.
abstract: Using systematic numerical simulations, we study the self-assembly of elongated curved nanoparticles on lipid vesicles. Our simulations are based on molecular dynamics of a coarse-grained implicit-solvent model of self-assembled lipid membranes with a Langevin thermostat. Here we consider only the case wherein the nanoparticle-nanoparticle interaction is repulsive, only the concave surface of the nanoparticle interacts attractively with the lipid head groups and only the outer surface of the vesicle is exposed to the nanoparticles. Upon their adhesion on the vesicle, the curved nanoparticles generate local curvature on the membrane. The resulting nanoparticle-generated membrane curvature leads in turn to nanoparticle self-assembly into two main types of aggregates corresponding to chain aggregates at low adhesion strengths and aster aggregates at high adhesion strength. The chain-like aggregates are due to the fact that at low values of adhesion strength, the nanoparticles prefer to lie parallel to each other. As the adhesion strength is increased, a splay angle between the nanoparticles is induced with a magnitude that increases with increasing adhesion strength. The origin of the splay angles between the nanoparticles is shown to be saddle-like membrane deformations induced by a tilt of the lipids around the nanoparticles. This phenomenon of membrane mediated self-assembly of anisotropically curved nanoparticles is explored for systems with varying nanoparticle number densities, adhesion strength, and nanoparticle intrinsic curvature.
authors.affiliation: Department of Biomedical Engineering, The University of Memphis, Memphis, TN 38152, USA and Department of Physics and Materials Science, The University of Memphis, Memphis, TN 38152, USA.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Olinger
authors.affiliation: Department of Biomedical Engineering, The University of Memphis, Memphis, TN 38152, USA and Department of Physics and Materials Science, The University of Memphis, Memphis, TN 38152, USA.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Spangler
authors.affiliation: Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India. sunil@iitm.ac.in.
authors.forename: P B Sunil
authors.initials: PB
authors.lastname: Kumar
authors.affiliation: Department of Physics and Materials Science, The University of Memphis, Memphis, TN 38152, USA. mlaradji@memphis.edu.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Laradji
mesh_terms: D016880:Anisotropy; D008051:Lipid Bilayers / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D053758:Nanoparticles / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D008055:Lipids; D008081:Liposomes