Constructing biocompatible carboxylic curdlan-coated zein nanoparticles for curcumin encapsulation

In this study, carboxylic curdlans with different carboxylate contents, molecular weights (MWs), and chain conformations (Cur-8, Cur-24, and Cur-48) were developed as hydrophilic coatings for hydrophobic zein nanoparticles (ZNPs) to encapsulate curcumin. The results showed that the freshly prepared curcumin-loaded ZNPs (ZC) had spherical structures, a particle size of ~183.0 nm, a zeta potential of +17.7 mV, and an encapsulation efficiency of 66.7%. The anionic carboxylic curdlan coating on the surface of ZC affected the particulate and physicochemical characteristics of the encapsulated curcumin and effectively improved its water dispersibility, photo- and thermostability, and sustained release behavior in aqueous environments. These properties were correlated with the carboxylate content, MW, and chain conformation of the carboxylic curdlans. The observed improvements were attributed to hydrogen bonding, hydrophobic and electrostatic interactions among curcumin, ZNPs, and carboxylic curdlans. The curcumin encapsulated in the Cur-24-coated ZNPs exhibited stronger antioxidant capacity in vitro than the other samples. Therefore, carboxylic curdlan-coated ZNPs have considerable potential for use in hydrophobic nutraceutical encapsulation.