Binary Complex Based on Zein and Propylene Glycol Alginate for Delivery of Quercetagetin.

Propylene glycol alginate (PGA) was found to be able to dissolve in aqueous ethanol solution and applied to interact with zein to form a noncovalent binary complex by the antisolvent coprecipitation method at pH 4.0. Quercetagetin (Q) was employed to explore the Q-delivery potential of Zein-PGA binary complex. A fruit tree-like microstructure was observed for Zein-PGA binary complex as its "branches" were closely adsorbed by zein particles. A solid sponge-like entity was formed after lyophilization of Zein-PGA binary complex colloidal dispersion. A synergistic effect was found between zein and PGA on improving the entrapment efficiency and loading capacity of Q. The incorporation of Q at a high concentration induced a significant effect on the tertiary structure of zein. Electrostatic attraction, hydrogen bond, and hydrophobic effects were mainly involved in the interactions between zein and PGA. Schematics with four possible structures were proposed to explain the formation mechanism of composites.