Fabrication of coated bovine serum albumin (BSA)–epigallocatechin gallate (EGCG) nanoparticles and their transport across monolayers of human intestinal epithelial Caco-2 cells
The bovine serum albumin (BSA)–epigallocatechin gallate (EGCG) nanoparticles were fabricated using a desolvation method, and coated with poly-ε-lysine or chitosan. BSA–EGCG nanoparticles (BEN), poly-ε-lysine coated BSA–EGCG nanoparticles (PBEN), and chitosan coated BSA–EGCG nanoparticles (CBEN) had a spherical morphology and a size of 186, 259, and 300 nm, respectively. The loading efficiency of EGCG in these nanoparticles was 32.3%, 35.4%, and 32.7%, whereas the loading capacity was 18.9%, 17.0%, and 16.0% (w/w), respectively. Poly-ε-lysine or chitosan coating prevented the aggregation of nanoparticles at pH 4.5–5.0. However, they caused particle aggregation at pH 6.5–7.0. BEN had negative zeta-potentials between pH 4.5 and 6.0. Poly-ε-lysine or chitosan coating changed the zeta-potentials to positive. The release study of EGCG from the nanoparticles in the simulated gastric or intestinal fluid with or without digestive enzymes showed that poly-ε-lysine and chitosan coatings delayed EGCG release from the nanoparticles. Poly-ε-lysine or chitosan coating improved the stability of EGCG during storage at 60 °C compared with EGCG in the uncoated particles. EGCG in BEN, PBEN, and CBEN had a decreasing apparent permeability coefficient (Papp) on Caco-2 monolayers, whereas pure EGCG showed relatively stable Papp during the incubation over time. EGCG in CBEN showed significantly higher Papp, suggesting that chitosan coated BSA–EGCG nanoparticles may improve the absorption of EGCG.