Cargo loading within ferritin nanocages in preparation for tumor-targeted delivery

Ferritins are spherical iron storage proteins within cells, composed of 24 subunits of two types, heavy-chain ferritin (HFn) and light-chain ferritin. Ferritins auto-assemble naturally into hollow nanocages with an outer diameter of 12 nm and an interior cavity 8 nm in diameter. Since the intrinsic tumor-targeting property of human HFn was first reported in 2012, HFn has been extensively explored for tumor-targeted delivery of anticancer drugs and diagnostic molecules, including radioisotopes and fluorophores, as well as inorganic nanoparticles (NPs) and chemotherapeutic drugs. This protocol provides four detailed procedures describing how to load four types of cargoes within HFn nanocages that are capable of accurately controlling cargo loading: synthesis of inorganic metal nanoparticles within the cavity of a wild-type human HFn nanocage (Procedure 1, requires similar to 5 h); loading of doxorubicin into the cavity of a wild-type human HFn nanocage (Procedure 2, requires similar to 3 d); loading Gd3+ into the cavity of a genetically engineered human HFn nanocage (Procedure 3, requires similar to 20 h); and loading Cu-64(2+) radioisotope into the cavity of a genetically engineered human HFn nanocage (Procedure 4, requires similar to 3 h). Subsequent use of these HFn-based formulations is advantageous as they have intrinsic tumor-targeting capability and lack immunogenicity. Human HFn generated as described in this protocol can therefore be used to deliver therapeutic drugs and diagnostic signals as multifunctional nanomedicines.

Automated summary

Ferritins are iron storage proteins that can be used for targeted delivery of anticancer drugs and diagnostic molecules. This study provides detailed procedures for loading different types of cargoes into ferritin nanocages for controlled delivery.