Reducing disulfide bonds as a robust strategy to facilitate the self-assembly of cod protein fabricating potential active ingredients-nanocarrier

In this study, a novel method was developed to encapsulate hydrophobic compounds by self-assembly of cod protein (CP) triggered by breaking disulfide bonds. Curcumin (Cur), a representative lipid-soluble polyphenol, was selected as a model to evaluate the potential of CP nanoparticles as novel and accessible nanocarriers. Results showed that the protein structure gradually unfolded with increasing dithiothreitol (DTT) concentration, indicating that S-S cleavage was conducive to forming a looser structure. The resultant unfolded CP exposed more hydrophobic sites, facilitating its interaction with hydrophobic compounds. The encapsulation efficiency (EE) of formed CP-Cur nanoparticles was relatively high, reaching 99.09%, 98.8%, and 89.77% when the mass ratios of CP to Cur were 20:1, 10:1, and 5:1 (w/v), respectively. The hydrophobic interaction, weak van der Waals, and hydrogen bond were the forces contributing to the formation of CP-Cur nanoparticles, whereas the hydrophobic interaction played a crucial role. The CP-Cur complex exhibited increased stability and a homogeneous-stable structural phase. Thus, this research not only proposed a novel and simple encapsulation method of hydrophobic bioactive compounds but also provided a theoretical reference for the application of reductants in food or pharmacy system.