Effects of calcium ions on the particle performance of luteolin-loaded zein-gum arabic-tea polyphenols ternary complex nanoparticles

Zein-gum arabic-tea polyphenols ternary complex nanoparticles have been developed for the encapsulation of luteolin, but there are still shortages existed in their particle properties such as encapsulation efficiency, stability, and release ability of luteolin. To improve their performance, calcium ions (Ca2+) were employed as a cross-linking stabilizer to investigate their effects on particle properties and functional performance. Particle parameters, physicochemical stability, antioxidant activity, and in vitro simulated gastrointestinal digestion were evaluated based on zetasizer measurement and multi-spectral methods, which were analyzed using Graphpad Prism v6.0.2. As a result, low concentrations of Ca2+ induced the formation of smaller and more compact nanoparticles with improved luteolin encapsulation efficiency, while higher concentrations had the opposite effect. Hydrophobic, electrostatic, and hydrogen bonding interactions were found to be responsible for nanoparticle assembly and stability with Ca2+ incorporation. Appropriate amounts of Ca2+ promoted the physicochemical stability of the nanoparticles under different conditions such as pH, salt ion concentration, temperature, and storage time. Additionally, low levels of Ca2+ strengthened the antioxidant activity of the nanoparticles and improved sustained release of luteolin under in vitro gastrointestinal conditions. These findings suggest that zein-gum arabic-tea polyphenols nanoparticles assembled with Ca2+ have potential applications as a delivery system for bioactive substances.