Microscale droplets covered by amphiphilic gold nanoparticles with various ligand ratios and concentrations.

We describe a simple and reliable route for forming microscale droplets covered with amphiphilic gold nanoparticles (AuNPs) functionalized with mixed hydrophilic and hydrophobic ligands on the AuNP surface. When an aqueous solution of amphiphilic AuNPs was mixed with hexane, the hexane (or water) droplets covered with amphiphilic AuNPs in the water (or hexane) phase were created, in which amphiphilic AuNPs in water phase migrated to the hexane-water interface. The extent of AuNP migration to the interface could be tuned by the ratio of the hydrophobic to hydrophilic ligands on the AuNP surface and the overall concentration of AuNPs.