Final Report Summary - ACCARC (Engineering of an Artificial Capsidic Enzyme for Aqueous Dirhodium Catalysis) Supercharging can endow a protein scaffold with new properties. By computational design, the surface of the protein nanocage ferritin was reengineered to produce a supercharged nanocage. The supercharged ferritin binds to negatively charged surfaces, and retains high thermostability. Synthesis of iron-oxide nanoparticles enables monitoring of the spatial localization of the nanocages in transfection experiments. Supercharged ferritin is readily incorporated into cells of a human cancer cell model. By tuning the electrostatic interactions between supercharged ferritin and a larger redesigned protein nanocage (AaLS 13) nested, Matryoshka-type structures were obtained, with several iron loaded, supercharged ferritin nanocages encapsulated within the larger cage. These experiments open up new avenues towards the construction of nano-sized structures such as artificial organelles or microcompartments.