Novel soy β-conglycinin nanoparticles by ethanol-assisted disassembly and reassembly: Outstanding nanocarriers for hydrophobic nutraceuticals

The development of protein-based particles or nanoparticles to act as efficient (nano)carriers for poorly soluble nutraceuticals has attracted increasing interests in the food and pharmaceutical fields. In the work, we reported a novel ethanol-assisted disassembly and reassembly strategy to fabricate a kind of soy β-conglycinin (β-CG; a major storage globulin from soybeans) nanoparticles to perform as highly efficient nanocarriers for hydrophobic nutraceuticals (using curcumin as a model bioactive). When the β-CG was treated by ethanol at high concentrations ([E]; e.g., >30%, v/v), its structure gradually unfolded, and accordingly, the protein denaturation and aggregation occurred. When the ethanol was removed by a dialysis, the denatured and aggregated β-CG would further reassemble to form nanostructured particles. The size and morphology of these reassembled particles could be well modulated by varying the initial [E] in the range 30–70% (v/v). In general, increasing the [E] led to a progressive increase in protein aggregation, as well as a strengthening of particle compactness. In addition, the presence of curcumin in the ethanol solutions greatly accelerated the ethanol-induced aggregation of the protein, or facilitated the formation of large reassembled particles. Interestingly, the reassembled β-CG particles at [E] = 40% exhibited a highest capacity to load curcumin, with a maximal loading amount reaching approximately 13.7 g curcumin/100 g protein. The encapsulation performance of curcumin in these reassembled particles was closely associated with the extent and rate of ethanol-induced structural unfolding and aggregation of β-CG. The curcumin encapsulated in these reassembled particles exhibited a much greater stability and bioaccessibility than free curcumin. The findings provide a facile and food-biocompatible process to develop soy protein-based nanoparticles as efficient carriers for poorly soluble nutraceuticals, thus exhibiting a great potential to be applied in food and pharmaceutical fields.