Interactions of End-functionalized Nanotubes with Lipid Vesicles: Spontaneous Insertion and Nanotube Self-Organization

Meenakshi      Dutt; Michael      J. Nayhouse; Olga      Kuksenok; Steven      R. Little; Anna      C. Balazs

Abstract

Via Dissipative Particle Dynamics (DPD) approach, we study the spontaneous insertion of amphiphilic nanotubes into a lipid vesicle, which is immersed in a hydrophilic solvent. Individual lipids are composed of a hydrophilic head group and two hydrophobic tails. Each nanotube encompasses an ABA architecture, with a hydrophobic shaft (B) and two hydrophilic ends (A). To facilitate the selective transport of species through the nanotubes, we introduce hydrophilic tethers at one end of the tube. We show that nanotubes initially located in the host solvent spontaneously penetrate the vesicles membrane and assume a transmembrane position, with the hydrophilic tethers extending from the surface of the vesicle. Adding nanotubes one at a time after the previous nanotube has been inserted, we characterize the interactions among the nanotubes that have self-assembled into the vesicles membrane and focus on their clustering within the membrane. We also show that the nanotube insertion and clustering within the vesicle strongly affects the vesicle shape in cases of a sufficiently large number of tubes. Ultimately, these nanotube-lipid systems can be used for creating hybrid controlled release vesicles.

Keywords: Hybrid vesicle, Bicelle, Self-assembly, Lipids, End-functionalized nanotubes, Nanotubes Clustering, Nanotube-lipids interactions, Nanoporous lipid vesicles, Hairy nanotubes, Dissipative Particle Dynamics, Tripod-like nanotubes assemblies, Tetrapod-like nanotubes assemblies, Smectic-like nanotubes assemblies