Genipin-enriched chitosan-Zein nanoparticles for improved curcumin encapsulation.

Polysaccharide-protein nanocomplexes are considered one of the desired systems to encapsulate bioactive compounds. The study prepared chitosan (CS)/genipin (GP)/zein nanoparticles with chemical cross-linkage for encapsulating and releasing curcumin. Fourier transform infrared spectra demonstrated that cross-linkage between molecules was attributed to electrostatic interactions and the formation of amido bonds and hydrogen bonding. Transmission electron microscopy showed that all prepared nanoparticles showed a spherical morphology. Particularly, cinnamaldehyde screening -NH groups in CS significantly reduced the encapsulation efficiency of nanoparticles, demonstrating the significant role of the -NH group in CS-coated zein nanoparticles. Additionally, the encapsulation efficiency was largely increased to 82.3 % at the ratio of CS/GP/zein (w/w, 20:1:100), compared with 38.4 % using zein as a single encapsulation for curcumin. In vitro digestion, the addition of GP and CS decreased the release of curcumin from 84.8 % to 57.1 % after the initial digestion of 2 h. The GP/CS/zein particles retained 12 % of curcumin after 6- h of digestion, indicating the improvements in encapsulation efficiency and release properties.