Formation mechanism and stability of ternary nanoparticles based on Mesona chinensis polysaccharides-walnut protein hydrolysates for icariin delivery.

Polysaccharide-protein complexes have proven to be effective nano-carrier with high stability. In this work, walnut protein hydrolysates (WPH) prepared through limited enzymolysis were considered as encapsulation carriers to solve the limited water solubility and bioavailability of icariin, a bioactive compound in functional foods. The pH-driven method was employed to prepare WPH-icariin nanoparticles (WPHI). Their characterization, formation, digestive properties, and immunomodulatory activity were investigated. The results showed that WPHI possessed superior encapsulation efficiency (82.35 %) and loading capacity (137.2 μg/mg) for icariin. Its water solubility (1647 μg/mL) and bioavailability (94.86 %) were significantly improved, by over 80 and 30 times, respectively. The combination of WPH with icariin resulted in the formation of irregular lamellar structure through hydrophobic, electrostatic, and disulfide bonds interactions. Moreover, WPHI demonstrated significant immunomodulatory activity, and thermal and digestive stabilities (> 93 %), but extremely poor pH and salt tolerance. To address these issues, Mesona chinensis polysaccharide (MCP)-WPHI was prepared. The incorporation of MCP significantly improved the physicochemical stability of nanoparticles. Compared to WPHI, MCP-WPHI showed improved pH, thermal, salt tolerance (0-250 mM), and storage stability. This study expanded the application of WPH and MCP in delivering icariin while providing new insights for developing multifunctional high-nutritional-quality food ingredients.