Cellular uptake and cytotoxicity of chitosan-caseinophosphopeptides nanocomplexes loaded with epigallocatechin gallate.

Epigallocatechin gallate (EGCG) was successfully encapsulated in novel nanocomplexes assembled from bioactive peptides, caseinophosphopeptides (CPPs), and chitosan (CS), a natural cationic polymer. Their particle sizes and surface charges were determined to be in the range of 150.0±4.3 nm and 32.2±3.3 mV respectively. Crosslinking between the -NH3+ groups of CS with the -P=O- and -COO- groups of CPP, as well as the hydrogen bonding were confirmed from the FTIR results. Atomic force microscopy (AFM) images showed that EGCG loaded CS-CPP nanocomplexes were spherical in shape. Maintaining the surface charge as high as +32.2 mV, crosslinking CS with peptides reduced the cytotoxicity of CS nanoparticles. In addition, cellular internalization of EGCG-loaded CS-CPP nanoparticles was confirmed from green fluorescence inside the Caco-2 cells. The process of nanoparticle uptake was dose and time dependent in the range of time and concentration studied. Furthermore, the intestinal permeability of EGCG using Caco-2 monolayer was enhanced significantly as delivered by nanoparticles, which indicated the promising elevation of EGCG bioavailability.