Phospholipid vesicle-bound lysozyme to enhance permeability in human intestinal cells

Background: Oral peptide and protein drug delivery still remain the area of challenges for pharmaceutical scientists due to their low stability and permeability in gastrointestinal (GI) tract. In this study phospholipid vesicle-bound lysozyme were prepared and assessed for their physicochemical properties, secondary structure, and permeation across Caco-2 cells. Results: Lysozyme was found to be substantially bound onto negatively charged vesicles via electrostatic interaction as evidenced by zeta potential measurements regardless of cholesterol content. In contrast, the size of phospholipid vesicle-bound lysozyme became larger with the increasing cholesterol content. The secondary structure of vesicle-bound lysozyme examined by FTIR was unchanged compared to that in buffer solution. The apparent permeability of vesicle-bound lysozyme across Caco-2 cells monolayer was significantly enhanced with a size dependent manner compared to that of solution. Conclusion: The permeation across Caco-2 cell monolayers of phospholipid vesicle-bound lysozyme was demonstrated to be significantly enhanced with a size-dependent manner.