Fabrication and Characterization of Quercetagetin-Loaded Nanoparticles Based on Shellac and Quaternized Chitosan: Improvement of Encapsulation Efficiency and Acid and Storage Stabilities

Shellac can be used as an ideal delivery vehicle to deliver and protect the hydrophobic quercetagetin; the barriers such as low acid stability and encapsulation efficiency, however, heavily impede the application of shellac. The purpose of this work is to prepare quercetagetin-loaded shellac-quaternized chitosan nanoparticles (Que-Sh-QCS NPs) to overcome these challenges. Herein, quaternized chitosan, with 14% degree of substitution, was successfully synthesized via a quaternization modification. The concentration of quaternized chitosan over 0.05% can prevent the aggregation of shellac nanoparticles at the acid. The encapsulation efficiency of quercetagetin obviously increased from 37.92 to 65.48% with the concentration of QCS varying from 0 to 0.05%. Meanwhile, Que-Sh-QCS_0.05 NPs possessed good storage stability, antioxidant property, biocompatibility, and controlled release. Therefore, quaternized chitosan can improve the encapsulation efficiency and acid and storage stabilities of nutraceutical-loaded shellac nanoparticles, providing a new insight into the application of shellac in cosmetics, pharmaceuticals, and food.