Fabrication of egg white protein/phosphatidylcholine-EGCG co-assembled nanoparticles with sustained release in simulated gastrointestinal digestion and their transcellular permeability in Caco-2 cultures

Epigallocatechin-3-gallate (EGCG) is a kind of polyphenol with various biological activities but poor stability and bioavailability. The encapsulation of EGCG in a nano-delivery system effectively improves its shortcomings. In this research, co-assembled nanoparticles of egg white protein, phosphatidylcholine (PC), and EGCG (EW/PE1:5 NPs) were prepared by antisolvent precipitation to improve their bioavailability. The constructed EW/PE1:5 NPs had an average particle size of 172 nm, a ζ-potential of −26.1 mV, and a polymerization dispersion index (PDI) of 0.33. The encapsulation efficiency (EE) of EGCG was 88.09% and the loading capacity (LC) was 20.10%. UV spectra, FTIR, XRD and intermolecular force results indicated that hydrophobic, electrostatic and hydrogen bonding interactions contributed to the formation of EW/PE1:5 NPs. EW/PE1:5 NPs exhibited Fick diffusion and sustained release characteristics in simulated gastrointestinal digestion. In addition, the transcellular permeability of EW/PE1:5 NPs was significantly increased compared with free EGCG. At the same time, EW/PE1:5 NPs increased EGCG absorption transport and inhibited MRP2 and P-gp-mediated efflux transport. These results suggest that EW/PE1:5 NPs play a key role in improving the bioavailability of EGCG. Therefore, EW/PE1:5 NPs are expected to provide a theoretical basis for the design and development of functional foods or dietary supplements that synergistically enhance the bioavailability of EW, PC and other flavonoids.