Structure and phase transitions of the multilamellar DMPC membranes in presence of the DMSO and DESO

Abstract

The structure and phase transitions of the prepared and formed spontaneously multilamellar vesicles (MLVs) of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) in dimethyl sulfoxide (DMSO) and diethyl sulfoxide (DESO) were investigated using small angle neutron scattering (SANS). The both polar aprotic solvents increase the temperature of the main phase transition (Tm ). The pre-transition does not observed at sulfoxides mole fraction X = 0.2. The transition of the MLVs DMPC in the presence DMSO from gel to liquid-crystalline phase occurs at lower temperature. The method of the MLVs preparation has directly effects on the temperature of the main phase transition and its structure. The value of Tm is higher with ∼ 4.6 °C in case of the spontaneous forming MLVs from extruded ULVs. The thickness of the solvent layer for prepared MLVs is less by 4.0 Å in gel phase and by 5.6 Å in liquid-crystalline phase than the thickness of the solvent layer for spontaneously formed MLVs.