Effect of calcium chloride on the protein encapsulation and stability of proliposomal granules

The purpose of this study was to develop oral proliposomal granules incorporating CaCl2 in order to enhance the encapsulation efficiency (EE) of protein model drug after reconstitution. Proliposomal granules were prepared by a granulation process with a solid carrier, protein model drug, and lipid solution. The proliposomal granules were characterized in terms of particle size, EE, and loading capacity. Protein structure analysis and cellular viability were also examined. CaCl2, ranged 0.125-6.0% w/w, was successfully incorporated into the dried granules during the wet binding process of granulation. Reconstituted proliposomes with 1% w/w CaCl2 showed the highest EE among those examined. Different reconstituted diluents did not alter the EE, but had an impact on particle size and charge. The alpha-helical content (%), calculated from the mean molar ellipticity, was similar between protein drug alone and that with addition of CaCl2, indicating the preservation of structural integrity, as also confirmed by electrophoresis. CaCl2 -incorporated proliposomes were non-toxic to cells at the dose used. In conclusion, inclusion of CaCl2 into proliposomal granules enhanced the EE of protein drug showing optimal effects at 1% w/w with good preservation of protein integrity and cellular viability.