Hydrophilic co-assemblies of two hydrophobic biomolecules improving the bioavailability of silybin

Benefitting from the versatility and biocompatibility of food sourced materials, the construction of hybrid structures via their molecular interplay generates novel platforms with unexpected properties. In this work, two hydrophobic biomolecules were co-assembled into water-soluble amphiphiles at pH 7 by a facile pH-cycle approach. Wheat gluten proteins (WPs) and shellac were dissolved together at pH 12 followed by a one-step adjustment to pH 7, yielding nanospheres with a protein recovery over 90%. Structural characterization evidenced that shellac stiffened the protein backbones that were resistant against thermodynamically-favored folding. The reactions were proven to be initiated between the protein secondary structures and shellac, forming a relatively unfolded three-dimensional conformation during the acid-induced co-assembly. Silybin was employed as a hydrophobic bioactive model and was entrapped following the same procedure as the hybrid assembly, with a maximum loading of 102 mg g^-1 hybrid. The bioavailability of silybin loaded in shellac-WP co-assemblies was improved as assessed by cell proliferation assays, due to the improved dispersity and cell internalization of the co-assemblies. The preparation method based on a simple pH manipulation may be applied to encapsulate various hydrophobic bioactive compounds, apart from the silybin explored in this study.