Fabrication of stable zein nanoparticles by chondroitin sulfate deposition based on antisolvent precipitation method

The purpose of this work is to stabilize zein nanoparticles with anionic polysaccharides-chondroitin sulfate (CS) to overcome the poor colloidal stability of zein nanoparticles. The average molecular weight of CS was 20.51 kDa and the disaccharide composition of CS was 70.71% monosulfated disaccharide Di2S and 29.29% disulfated disaccharide Di2,6 diS. Zein/CS composite nanoparticles were fabricated by antisolvent precipitation method at pH 4.0. The optimal mass ratio of zein to CS was 1:1 (w/w). Zein/CS composite nanoparticles showed mean size of 148 nm and PDI < 0.2, maintaining great stability at pH 3.0 to 8.0. Meanwhile, these prepared nanoparticles were also stable to heat treatment and was stable to a range of ionic strength of 0-15 mM at pH 4.0 and 0-10 mM at pH 7.0. The composite nanoparticles exhibited regular spherical structures, and CS was deposited on the surface of zein mainly by electrostatic interactions. In the process, the addition of urea and sodium dodecyl sulfate indicated that it also involved both hydrogen bonding and hydrophobic interactions. In addition, cytotoxicity assay on human renal epithelial cells-293 cells indicated that zein/CS composite nanoparticles were essentially nontoxic.