Functionalized 'nanocages'

Adding an entry to the growing collection of custom-made nanoparticles, Northwestern University chemical engineers report a procedure for preparing "nanocages," a material characterized by 2-nm cages that have a porous cross-linked siloxane shell with amine groups anchored to the inside (J. Am. Chem. Soc. 2006, 128, 2776). The material may be useful in drug delivery applications or for selective catalytic reactions in which the shell windows restrict access to the nanocage interior on the basis of a reactant molecule's size. The synthesis strategy, developed by Young-Woong Suh, Yingmin Wang, Mayfair C. Kung, and Harold H. Kung, is based on forming nanosized micelles that contain head groups that can be polymerized into the cross-linked shell and hydrophobic tails containing carbamate units that can be converted to the amine groups. According to the team, the method provides flexibility in selecting the nature of the tethered functional group and the size of the cavity and shell opening.