Investigating the impact of cholesterol on magnetically aligned sphingomyelin/cholesterol multilamellar vesicles using static 31P NMR

The effect of cholesterol (5–40 mol%) on the magnetic induced orientation of sphingomyelin/cholesterol multilamellar vesicles (MLVs) was examined using static solid state ³¹P NMR spectroscopy. The orientation was modeled assuming an ellipsoidal deformation of the vesicles and was monitored as a function of cholesterol concentration and temperature. In addition, the static ³¹P chemical shift anisotropy (CSA) was used to assess the motional and dynamical changes occurring in the bilayer are reported. An exploration of the factors determining the magnetic orientation in sphingomyelin/cholesterol bilayers from the gel (s_o) to liquid crystalline (or liquid-ordered, l_o) phases is presented and discussed.