Epigallocatechin-3-gallate (EGCG),the most abundant tea catechin in green tea,is known as a strong natural antioxidant.However,the bioavailability of EGCG is very low,which was mainly caused by its very low intestinal absorption and poor stability in intestinal juice neutral and alkaline environments.Genipin cross-linked caseinophosphopeptide (CPP)-chitosan (CS) nanoparticles (smaller than 300 nm) showed significantly improved stability and adjustable release profile in gastrointestinal (GI) tract.Optimal purification of the nanoparticles was established by centrifugation to terminate the crosslinking reaction,which was further confirmed and characterized by FT-IR.Results from transmission electron microscopy (TEM),dynamic light scattering (DLS) and electrophoretic mobility (t-potential) measurements revealed that genipin crosslinking significantly prevented the burst broken of the CPP-CS nanoparticles in simulated stomach acid and their precipitation under neutral intestinal environment.Pepsin showed little impact on the nanoparticle colloid stability,however,trypsin induced their aggregations.Genipin crosslinking slowed down the bust release of (-)-epigallocatechin-3-gallate (EGCG) from the nanoparticles.The EGCG loaded nanoparticles showed strong cytotoxicity against cancer cells,meanwhile,the net nanoparticles demonstrated high biocompatibility.