Fig. 1

a Structure of ferritin verified by four reacting interfaces, in which the exterior, intersubunit and interior interfaces were reported to be used in a variety of applications. But the intrasubunit interface was put forward for the first time. b Highlight of intrasubunit interface within one subunit. c The ferroxidase center buried within the intrasubunit was redesigned into a new compartment which can specifically bind to gold ions by introducing Cys residues. d Site-directed synthesis of gold nanoclusters (Au NCs) within 24 four α-helix bundles of one ferritin molecule. e Compartmentalization of two different kinds of nanoparticles within one ferritin nanocage. The Au NCs were located within protein shell, while inorganic iron cores or bioactive organic cargoes were encapsulated within the ferritin inner cavity