Effect of adjusting pH and chondroitin sulfate on the formation of curcumin-zein nanoparticles: Synthesis, characterization and morphology

This study is aiming to investigate the stabilizing effect of chondroitin sulfate (CS) on the preparation of curcumin nanoparticles (NPs). The results showed that adding CS before the anti-solvent process of zein (Z) at pH7 could fabricate most stable NPs (Cur/CS/Z-pH7) with particle size of 197 +/- 5 nm and zeta-potential of -48.4 +/- 1.9 mV. The pH had a significant effect on the fabrication of NPs. Cur/CS/Z-pH7 was more stable than Cur/CS/Z-pH3, while Cur/Z-CS-pH3 was more stable than the Cur/Z-CS-pH7. According to the results of XRD, FTIR, DSC and CD, CS can form irreversible macromolecular complexes with zein through non-electrostatic interactions during the anti-solvent process (Cur/CS/Z-pH7, Cur/CS/Z-pH3). However, CS was adsorbed on the surface of Zein NPs by electrostatic interaction (Cur/Z-CS-pH7, Cur/Z-CS-pH3), when CS was added after anti-solvent process of zein. These results illustrated that it is better to add CS before the anti-solvent process of zein at neutral pH.