Construction of dual-compartmental micro-droplet via shrimp ferritin nanocages stabilized Pickering emulsions for co-encapsulation of hydrophobic/hydrophilic bioactive compounds

Pickering emulsion as a novel delivery system offers remarkable opportunities for the delivery of different food bioactive compounds and drugs. However, there are still remaining challenges when they are employed to co-delivery multiple cargos for synergetic functionalities, particularly concerning the synchronous delivery of compounds with different physicochemical properties. Herein, we developed a model dual-compartmental O/W Pickering emulsion system by utilizing ferritin nanocages whose structure provides one type of intrinsic chamber as Pickering emulsifiers for co-encapsulation of hydrophilic and hydrophobic bioactive compounds. Experiment results showed that ferritin nanocages adsorb at oil/water interface and form stable oil-in-water Pickering emulsions with droplet size being dependent on the oil/water ratio and ferritin concentration. Significantly, confocal laser scanning microscopy and transmission electron microscopy results displayed that the emulsification process does not destroy the shell-like structure of ferritin nanocages but triggers the assembly of ferritin nanocages into large-scale assemblies which finally adsorb at the oil-water interface, indicating the successful fabrication of dual-compartmental micro-droplets. Subsequently, chlorogenic acid and β-carotene were chosen as model hydrophilic and hydrophobic molecules for cargo loading studies. Chlorogenic acid molecules were encapsulated in ferritin cavity while β-carotene molecules were loaded in oil droplets. Notably, successful co-encapsulation of two bioactive compounds has subtle influences on the emulsion formation and droplet characteristics but improves the storage stability of bioactive compounds. This work highlighted that the ferritin-stabilized Pickering emulsions have great potential for the co-delivery of multiple food bioactive compounds or drugs, which might be beneficial for achieving their functionality in a synergistic manner.