Simultaneous small-angle/wide-angle X-ray scattering and differential scanning calorimetry study of the effects of glycerol on hydrated monoolein

Monoolein is a natural amphiphilic molecule. Many applications of monoolein have been reported in different fields, for example, the crystallization of membrane protein in a bicontinuous cubic phase of monoolein-water systems, drug delivery systems using hydrated monoolein. Glycerol acts as a cryoprotectant. In order to get basic information for the discussion of the cryoprotective mechanism of glycerol, the effects of glycerol on the structure and phase behavior of hydrated monoolein were investigated by means of simultaneous small-angle X-ray scattering, wide-angle X-ray diffraction and differential scanning calorimetry measurements. We found that addition of glycerol increases the lamellar crystal-to-bicontinuous cubic phase transition temperature and reduces the lattice constants of the cubic phase. We discuss the interaction between glycerol and monoolein from the results obtained in this study.