Co-assembly of quinoa protein isolate and shellac as nano-vehicles for naringenin: Characterization, formation mechanism, release behavior and cellular uptake

Naringenin (Nar) is a natural flavonoid with diverse health-promoting benefits. However, the bioavailability of Nar is significantly restricted due to its poor water-solubility, instability under physiological conditions, and limited absorption profile. In this study, a shellac-quinoa protein isolate (QPI) binary nanocomplex (SQP) was fabricated using the pH-shifting method for effectively delivering Nar. Isothermal titration calorimetry (ITC) and analysis of inner interactive forces revealed that the complexation between QPI and shellac was primarily driven by electrostatic and hydrophobic forces. Subsequently, Nar was successfully encapsulated within the stable and uniform SQP nanocomplex (Nar@SQP), achieving a high encapsulation capacity (94.52 % encapsulation efficiency and 14.68 % loading capacity). Meanwhile, the Nar@SQP nanoparticle exhibited excellent stability against pH, ionic strength, and long-term storage. Moreover, it also demonstrated sustained and slow-release characteristics during simulated gastrointestinal digestion. Compared to free Nar, the safe Nar@SQP nanoparticle effectively facilitated the cellular uptake of encapsulated Nar by Caco-2 cells, suggesting that Nar@SQP has a good potential to improve the bioavailability of Nar. Hence, these findings indicated that the developed Nar@SQP nanoparticle might hold significant promise as a nano-delivery system for hydrophobic bioactive nutrients, like Nar.