Nanoporous colloids: building blocks for a new generation of structured materials

Porous colloidal particles have recently attracted a renewed interest in both fundamental and applied research. The large internal surface area and adsorbent potential of porous particles have led to their widespread application in diverse fields, including sensing, catalysis, drug delivery, and separations. This review highlights recent advancements in the adsorption of molecular species and nanoparticles into nanoporous colloids, and the subsequent formation of colloidal composites, particle replicas, and ordered particle arrays. We begin with a brief introduction to the synthesis of porous colloidal particles that are commonly employed, followed by a survey of the use of porous particles as adsorbents for the immobilization and entrapment of nanoscale guest materials. Next, recently developed methods to control the release of entrapped materials as well as their templated use for assembling hollow capsules with entrapped guest materials are detailed. We subsequently highlight recent developments in the templated synthesis of nanoporous particles with an emphasis on mesoporous silica replicas. Finally, new opportunities for using porous colloidal particles in the assembly of ordered materials are discussed.