Effects of Ca2+ and Tannic Acid Crosslinking on Structure, Stability, and in vitro Digestion of Zein-Carboxymethyl Chitosan Nanoparticles Loaded with Quercetin

The potential of using a combination of tannic acid and Ca²⁺ as dual cross-linkers to enhance the performance of zein-carboxymethyl chitosan (Zein-CMCh) nanoparticles for quercetin encapsulation was investigated. In particular, the effect of Ca²⁺ concentration on the properties of the nanoparticles and on the stability of the encapsulated polyphenols was studied. Appropriate Ca²⁺ concentrations facilitated the formation of stable double cross-linked nanoparticles through hydrophobic, electrostatic, and hydrogen bonding interactions. These nanoparticles had a relatively high encapsulation efficiency (89.3%) for the quercetin. The dual cross-linking strategy significantly improved the nanoparticle stability against pH variations (2–8), thermal pr℃essing (30–90 ℃), and extended storage (30 d, retention > 80%). Ca²⁺-modified system demonstrated significantly enhanced antioxidant capacity and sustained gastrointestinal release. The stable double cross-linking delivery system based on the molecular interaction between polysaccharide-based carbohydrate polymers was used to encapsulate quercetin, which improved the bioavailability of quercetin and provided an idea for constructing a stable delivery system to realize the controlled and sustained release of active factors.