A metal-ligand complexation strategy using ruthenium - terpyridine interactions was utilized for the facile synthesis, of amphiphilic block copolymers which were self-assembled into spherical micelles and stabilized throughout their shell to afford well-defined nanoparticles. The labile metal-ligand bond at the nanoparticle core-shell interface was then readily broken to enable excavation to afford hollow completely hydrophilic nanocages which can no longer sequester hydrophobic small molecules. These nanocages also demonstrated pH responsiveness and could be further functionalized by the reintroduction of metals.