It's a trap! DNA polyhedra formed through molecular self-assembly may function as nanocapsules for the targeted delivery of encapsulated entities. This functional aspect was demonstrated for the most complex DNA-based platonic solid: During the stepwise amalgamation of discrete polyhedra to form icosahedra, gold nanoparticles (GNPs) were encapsulated from solution (see illustration and TEM image of icosahedral cages containing GNPs).