Chitosan-zein-icariin complexes modulate double emulsion phase transitions to potentiate absorption efficiency

This study developed a chitosan-zein-icariin ternary complex through reversed-phase precipitation to stabilize double emulsions using one-step emulsification method. Results indicated that icariin and chitosan-zein formed spherical microstructures via the rearrangement of hydrogen bonding networks and hydrophobic interactions. All complexes exhibited pale-yellow color and demonstrated single and uniform size distribution. The thermal stability and interfacial contact angle of the complexes significantly decreased with the incorporation of icariin. The prepared double emulsion microstructures displayed multi-chambered configurations due to polarity differences, solidifying during cold storage as a result of phase shifts in coconut oil, which led to an increased storage modulus. While the double emulsion microstructure showed enhanced storage stability, droplet size increased markedly when subjected to NaCl and temperature variations. Following in-vitro digestion, the double emulsion microstructure disintegrated; average particle size decreased, resulting in the release of icariin from the ternary complex during intestinal phases, thereby enhancing bioaccessibility. Furthermore, it was observed that icariin within the ternary complex influenced absorption efficacy based on its concentration levels, as evidenced by Caco-2 cell studies, though this effect was greater than that observed for the zein-icariin binary complex. The results of this study provide a theoretical foundation for efficient delivery systems involving hydrophobic multivariate complexes.