Fabrication and Characterization of Stable Soy β-Conglycinin–Dextran Core–Shell Nanogels Prepared via a Self-Assembly Approach at the Isoelectric Point

The preparation of soy β-conglycinin–dextran nanogels (∼90 nm) went through two stages, which are safe, facile, and green. First, amphiphilic graft copolymers were formed by dextran covalently attaching to β-conglycinin via Maillard dry-heating reaction. Second, the synthesized conjugates were heated above the denaturation temperature at the isoelectric point (pH4.8) so as to assemble nanogels. The effects of pH, concentration, heating temperature, and time on the fabrication of nanogels were examined. The morphology study displayed that the nanogels exhibited spherical shape with core–shell structures, which was reconfirmed by zeta-potential investigation. Both circular dichroism spectra and surface hydrophobicity analyses indicated that the conformations of β-conglycinin in the core of nanogels were changed, and the latter experiment further revealed that the hydrophobic groups of β-conglycinin were exposed to the surface of protein. The nanogels were stable against various conditions and might be useful to deliver hydrophobic bioactive compounds.