Co-encapsulation of Epigallocatechin Gallate (EGCG) and Curcumin by Two Proteins-Based Nanoparticles: Role of EGCG

In this study, a novel plant-protein-based nanoparticle delivery system was developed to encapsulate and stabilize curcumin and epigallocatechin gallate (EGCG) with different polarities. The strongly hydrophobic curcumin was embedded within the hydrophobic cores of zein nanoparticles using an antisolvent method, while the weakly hydrophobic EGCG was adsorbed to the region between the zein core and caseinate shell. The physicochemical properties, structure, and stability of the core-shell particles were characterized using dynamic light scattering, particle electrophoresis, fluorescence spectroscopy, and Fourier transform infrared spectroscopy. The bioaccessibility of curcumin in the core-shell nanoparticles was determined using a simulated gastrointestinal tract. Mean particle diameters around 100-200 nm could be produced by modulating the mass ratio of curcumin to zein. The encapsulation efficiency of curcumin in the core-shell nanoparticles was higher (96.2%) in the presence of EGCG than in its absence (77.9%). Moreover, the water dispersibility and 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity of the nanoparticles were significantly improved in the presence of EGCG. The simulated gastrointestinal tract experiments indicated that curcumin had a high bioaccessibility in the optimized core-shell nanoparticles. Overall, our findings suggest that EGCG can be used to improve the functional properties of curcumin-loaded zein-caseinate nanoparticles, which may increase their use in food, cosmetics, and pharmaceutical applications.