Development of pH-driven zein/tea saponin composite nanoparticles for encapsulation and oral delivery of curcumin

The purpose of this paper was to overcome the challenges of curcumin by zein/tea saponin composite nanoparticles (Z/TSNPs) without any organic reagents and high-energy equipment. The spherical Z/TSNPs exhibited good physical stability, the conditions of which included pH at 5.0–8.0, heating at 80 ℃, ionic strength within 100 mM, and storage at 25 ℃ for 30 days. Meanwhile, Z/TSNPs showed excellent redispersibility. Z/TSNPs were used to encapsulate and deliver curcumin (Cur-Z/TSNPs), showing encapsulation efficiency and loading capacity of 83.73% and 22.33%, respectively. Cur-Z/TSNPs exhibited good chemical stability during storage, and the effect of light on Cur-Z/TSNPs was smaller than that of free curcumin. Furthermore, Cur-Z/TSNPs improved the solubilization and bioaccessibility of curcumin about 290 and 5 times, respectively. Besides, the encapsulation changed the crystalline state of curcumin to amorphous, and the pH-driven mechanism was probably related to hydrogen bonding, hydrophobic and electrostatic interactions.