Channel directed rutin nano-encapsulation in phytoferritin induced by guanidine hydrochloride

Phytoferritin cage has a nano-sized cavity to encapsulate bioactive molecules. In this work, a novel approach is presented that guanidine hydrochloride (GuHCl) (2 mM) can expand the channel of apo-soybean seed ferritin (apoSSF) and promote the encapsulation of rutin molecules in apoSSF at pH 7.0 without the disassembly of the protein cage. Upon removal of GuHCl from SSF, a rutin encapsulation ratio of 10.1% was obtained; and the prepared rutin-loaded ferritin nanoparticles were homogeneously distributed, showing a shell-like morphology with a size of 12 nm. By virtue of this interesting method, core molecules can be encapsulated within the ferritin cage in a benign condition without extreme pH changes, which is beneficial for the stability and bioactivity of the pH-sensitive molecules in food encapsulation and delivery of functional molecules.