The Binding and Aggregation of Anisotropic Nanoparticles on Cylindrical Lipid Membranes

Abstract

Nanoparticle (NP) based technologies, which are becoming increasingly prevalent component in industrial development, have many important potential medical applications including diagnosis, imaging, drug delivery, hypothermia, and photothermal therapy. Since the plasma membrane is the point of entry of cells, biomedical applications of NPs require understanding of their interactions with lipid membranes (LMs). Mixing NPs with soft materials, such as polymers and liquid crystals, often leads to cooperative behavior of NPs manifested in their self-assembly. Recent experiments have shown that the adhesion of NPs onto LMs leads to their aggregation. In order to understand this cooperative behavior, we conducted large scale and systematic molecular dynamics simulations of spherical NPs self-assembly mediated by their adhesion onto LMs using a coarse-grained implicit solvent model. In addition to the linear chains and tubes, indicated earlier by other researchers using dynamic triangulation Monte Carlo method, we observed additional novel self-assemblies corresponding to bitubes and rings. The phase diagram of the system is determined as a function of NPs size, adhesion strength, and number density on the LM. The stability of these self-assemblies, particularly bitubes and rings, was investigated using simulated annealing as well as free energy calculations.