Directional self-assembly of ligand-stabilized gold nanoparticles into hollow vesicles through dynamic ligand rearrangement.

Here we report a novel approach to prepare all-nanoparticle vesicles using ligand-stabilized gold particles as a building block. Hydroxyalkyl-terminated gold nanoparticles were spontaneously organized into well-defined hollow vesicle-like assemblies in water without any template. The unusual anisotropic self-assembly was attributed to the ligand rearrangement on nanoparticles, which leads to increased hydroxyl group density at the nanoparticle/water interface. One-dimensional strings were formed instead of vesicles with increasing surface ligand density, which supports the hypothesis. The size and the wall thickness of vesicles were controlled by adjusting the concentration of nanoparticles or by adding extra surfactants. The work presented here highlights the dynamic nature of surface ligands on gold particles and demonstrates that the combination of ligand rearrangement and the hydrophobic effect can be used as a versatile tool for anisotropic self-assembly of nanoparticles.