Phosphatidylcholine Membrane Fusion Induced by Dimethyl Sulfoxide and Diethyl Sulfoxide

Abstract

The kinetics of unilamellar vesicle fusion induced by the addition of dimethyl sulfoxide (DMSO) and diethyl sulfoxide (DESO) with mole fractions of 0.1 and 0.2 is studied in the liquid-crystal phase using small-angle neutron scattering. Multilamellar vesicles formed due to the partial fusion of unilamellar vesicles of 1,2-dimyristoyl-sn-glycero-3-phosphadylcholine (DMPC) with the addition of DMSO (Х_DMSO = 0.1, 0.2) and DESO (Х_DESO = 0.2) are stable for a long time. The cooling–heating process does not affect the stability of the formed systems. The presence of DMSO and DESO with a mole fraction of 0.2 leads to disappearance of the ripple phase. The addition of DESO to the unilamellar vesicles of DMPC in D₂O with a mole fraction of 0.1 does not affect the structure of unilamellar vesicles for 5–15 minutes after adding the sulfoxide in the liquid-crystal phase. Three hours later, a stable system consisting of unilamellar vesicles with a lipid bilayer thickness of 27.3(2) Å and multilamellar vesicles with a repeat distance of d = 43.6(2) Å is formed. During cooling, multilamellar vesicles are destroyed in the region of the main phase transition (T'_m = 24.8(9)°C for the investigated system) and unilamellar vesicles are formed.