A versatile 'click chemistry' route to size-restricted, robust, and functionalizable hydrophilic nanocrystals.

A versatile addition-crosslinking route is developed to transfer various hydrophobic nanocrystals into water. By assembling amphiphilic ligands and then crosslinking through 'click chemistry', a monolayer of polymer forms on the nanocrystal surface, leading to excellent stability and limited increase in hydrodynamic diameter. These nanocrystals can also be further functionalized easily for various applications such as catalysis, bioimaging, and medical therapy.