Formation of soy protein nanoparticles with varied loading capacity by controlled enzymatic hydrolysis and their co-assembly with Vitamin D3

Abstract

In the present study, rational designed soy protein nanoparticles (SNPs) with different subunit compositions and loading capacities were fabricated via Pancreatin-induced hydrolysis taken Vitamin D3 (VD3) as a hydrophobic cargo. Further assembly behavior of SNPs caused by VD3 incorporation was also noticed and analyzed. Results showed that hydrolysis to 2.98% degree of hydrolysis (DH) (Pan1) facilitated the formation of a nanoparticle structure with hydrophobic cores originated from moderate degradation of 7 S and A subunits of 11 S. This core-shell structure had a higher loading capacity towards the VD3 and was further strengthened upon VD3 addition. Further hydrolysis to 10.96% DH (Pan2) caused further degradation of subunits and the extension of protein structure, accelerating aggregation through protein-protein interactions. The coexistence of aggregates as well as degradation fragments showed different binding patterns with VD3 and the resultant mixture was in non-uniformed size distribution. Further hydrolysis to 18.04% DH (Pan3) caused severe precipitation due to hydrophobic aggregation and the hydrophilic peptides retained had no apparent hydrophobic domain for the entrapment of VD3. Interestingly, VD3 would tend to form a hydrophobic core in situ through hydrophobic hydration with Pan3, resulting in a more ordered structure. These findings suggest that enzymatic hydrolysis could be a useful tool for the rational design of nanostructure for bioactive delivery where the co-assembly behavior calls for attention.