Hollow Polymer Nanoparticles for Drug-Delivery Vehicles. We are interested in constructing hollow polymer nanoparticles (hPNPs) for use as selective/specific drug-delivery carriers that can have high drug-loading capacity, easy surface modification, and excellent stability. These polymeric materials can be reliably prepared by using a conventional radical polymerization to grow a shell of polymer around monodipserse sacrificial inorganic silica nanoparticles having tunable sizes. This approach can allow for the synthesis and development of uniform core-shell nanoparticles with tunable shell thicknesses from the nanometer to micron size.