Succinylated ferritin as a novel nanocage-like vehicle of polyphenol: Structure, stability, and absorption analysis

Ferritin, a protein with an 8-nm cage structure, can encapsulate and deliver bioactive molecules. In this study, succinylation was adopted to modify plant ferritin to fabricate succinylated red been ferritin (SRBF) at pH 8.0. The SRBF was retained as a cage-like shape (12 nm diameter), while its secondary structure was altered, rendering higher negative charge accompanies by decreased surface hydrophobicity. The SRBF also demonstrated favorable property of reversible assembly regulated by pH-transitions (pH 2.0/7.0), thus enabled successful encapsulation of epigallocatechin gallate (EGCG) for fabrication of EGCG-loaded SRBF complexes with a diameter of ~12 nm. Succinylation enhanced the thermal stabilities of ferritin and the embedded EGCG. Moreover, SRBF markedly improved the transport efficiency of EGCG in Caco-2 monolayers relative to EGCG and that encapsulated in unmodified ferritin. These findings have extended the succinylation reaction for the cage-like protein modification, and facilitated the usage of ferritin variant in delivery of bioactive molecules.