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 PO− 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.