β-Lactoglobulin-chlorogenic acid conjugate-based nanoparticles for delivery of (-)-epigallocatechin-3-gallate

beta-Lactoglobulin (BLG)-chlorogenic acid (CA) conjugates were generated by a free radical induced grafting method. BLG-CA conjugates showed better antioxidant activities than BLG. The antioxidant activity increased with the increase of CA substitution. The particle sizes of (-)-epigallocatechin-3-gallate (EGCG)-loaded nanoparticles prepared by the anti-solvent method were 110.3, 107.4, and 105.8 nm for BLG, BLG-CA (low), and BLG-CA (high), respectively. The encapsulation efficiencies of EGCG in BLG, BLG-CA conjugate (low), and BLG-CA conjugate (high) nanoparticles were 72.9%, 71.8%, and 73.5%, respectively. The chemical stabilities of EGCG in both BLG-CA nanoparticles were significantly higher than in BLG nanoparticles. BLG-CA conjugate (high) showed better EGCG retention than BLG-CA conjugate (low) in simulated gastrointestinal digestion fluid. Little EGCG was released in both BLG nanoparticles and BLG-CA nanoparticles under simulated gastric digestion. The release of EGCG in BLG-CA nanoparticles was less than that in BLG nanoparticles, indicating that CA conjugating protected BLG from the digestive enzymes.