Genipin-mediated subunit-subunit crosslinking of ferritin nanocages: Structure, properties, and its application for food bioactive compound sealing

Ferritin proteins are promising nano-carriers for bioactive compound delivery. However, the disassembly properties under acidic/alkaline conditions pose risks of cargo leakage. Herein, genipin-mediated chemical crosslinking method was provided as an alternative and effective strategy to construct robust ferritin nanocarrier through controlled-intramolecular conjugation. As indicated by SDS-/Native- PAGE, the crosslinking degree gradually increased with incubating time prolonging. CD results showed that the cross-linking would decrease α-helix content from 78.4 % to 52.7 % upon 6 h incubation. However, TEM images showed that the genipin-modification has subtle influence on its shell-like structure. Remarkably, the cross-linking can be well controlled by intramolecular subunit-subunit conjugation rather than intermolecular conjugation, giving an excellent monodispersity. Importantly, the covalent cross-linking can tight neighboring subunits and inhibit its disassociation, finally inhibiting the leakage of encapsulated-cargos from ferritin cavity under acidic environments. Such findings suggested that the genipin-mediated cross-linking strategy can fabricate robust nano-carriers for bioactive compound delivery.