Fabrication and characterization of protein-phenolic conjugate nanoparticles for co-delivery of curcumin and resveratrol

Curcumin and resveratrol are polyphenols widely used as nutraceuticals because of their strong antioxidant activities and potential health benefits. In this study, the possibility of improving their water-dispersibility, chemical stability, and bioaccessibility using core-shell nanoparticles was examined. The hydrophobic core was fabricated from zein-epigallocatechin gallate conjugates using an antisolvent precipitation method, while the shell was fabricated by coating the core with a biosurfactant (rhamnolipid). The yield, size, morphology, charge (ζ-potential), and loading efficiency of these core-shell nanoparticles were characterized. The nanoparticles formed were anionic spheres with mean diameters <200 nm. Spectroscopic analyses suggested that curcumin and resveratrol were present in an amorphous form in the nanoparticles. The loading efficiencies of nanoparticles containing either curcumin or resveratrol were around 63% and 78%, while they were around 71% and 85% for nanoparticles containing both curcumin and resveratrol, respectively. The nanoparticles protected the two nutraceuticals from degradation while preserving their antioxidant activity. The bioaccessibility for both curcumin and resveratrol was significantly improved when the core-shell nanoparticles were mixed with lipid droplets. This study showed that resveratrol and curcumin could be co-encapsulated in mixed colloidal delivery systems designed to improve their stability and bioaccessibility. These delivery systems may be useful for application in functional foods, supplements, or pharmaceuticals.