Manipulating the Monolayer: Responsive and Reversible Control of Colloidal Inorganic Nanoparticle Properties

For a wide range of nanomaterials, surface-bound molecules play a central role in defining properties, and are key to integration with other components-be they molecules, surfaces, or other nanoparticles. Predictable and general methods for manipulating the surface monolayer are therefore crucial to exploiting this new region of chemical space. This review highlights limitations of the few established methods for controlling nanoparticle-bound molecular functionality, then focuses on emerging new strategies. In particular, approaches that can achieve stimuli-responsive and reversible modification of surface-bound molecules in colloidal solution are examined, with an emphasis on using these methods to control nanoparticle properties such as solvent compatibility, catalytic activity and cytotoxicity. Finally, the outstanding challenges and future potential for precisely controlled nanoparticle-bound monolayers are discussed.