Enhancing the colloidal stabilities of zein nanoparticles coated with carboxylic curdlans

Abstract

In this study, anionic carboxylic curdlans (Cur-8, Cur-24 and Cur-48) with different molecular properties and chain conformations were employed for the fabrication of carboxylic curdlan-coated zein nanoparticles (ZNPs) to overcome the poor colloidal stability of plain ZNPs. The results showed that the nanosized carboxylic curdlan-coated ZNPs prepared with 1.0 mg/mL ZNPs, 0.5 mg/mL carboxylic curdlans, and a 1:1 ZNP/carboxylic curdlan volume ratio (v/v) at pH 4.0 exhibited spherical shapes and negative zeta potentials. These carboxylic curdlan-coated ZNPs exhibited improved salt, thermal, and storage stability and good redispersibility compared with bare ZNPs. The carboxylate contents, molecular weights (MWs), and chain conformations of carboxylic curdlans considerably affected the particle sizes, electrical characteristics, microstructures, and colloidal stabilities of carboxylic curdlan-coated ZNPs. Specifically, compared with Cur-8, Cur-24 and Cur-48 with lower MWs, higher carboxylate contents and more extended flexible chains coated on the outer layer of ZNPs exhibited more pronounced colloidal stability. Moreover, electrostatic interactions, hydrogen bonds and hydrophobic effects contributed to the stabilization of ZNPs after coating with carboxylic curdlans, together with enhanced surface hydrophilicity. Thus, carboxylic curdlan-stabilized ZNPs can be developed as novel nanocarriers for various lipophilic nutrient delivery applications.