Lipid liquid crystalline phase and starch particle mixed formulations

Abstract: Lipid liquid crystals (LLC) have been studied widely because of their broad application in both food- and pharmaceutical industry. Inverse bicontinuous cubic phase of LLC have been of particular interest as it has three-dimensional structure and has been proven to be able to incorporate and deliver substances (e.g. topical drug delivery). There is a growing interest to prepare hybrid responsive lipid and polymer system. This study concerns how starch particles influence an LLC system. The system consists of capmul glycerol monooleate (GMO-50) and diglycerol monooleate (DGMO) and are mixed with different water concentration and weight percentage of native or modified starch particles. These has been proven, from small angle x-ray scattering and Cryo-TEM imaging, to form inverse bicontinuous cubic phases. At lower temperatures and water concentration, the system favorably forms gyroid type of bicontinuous cubic phase with space group Ia3d. At high temperatures and water concentrations, the system instead forms cubic crystal symmetry of space group Pn3m. Even at high concentration of starch particles, the system is favoring space group Pn3m. This tells that starch particles regulates the hydration and determines which one of the two crystal symmetries are formed. Further studies should be made in order to fully understand the lipid system with starch. Nevertheless, with this study it has proven new possibilities of using starch for materials based on lipid-polymer responsive layers.