Effect of TFE, HFIP, and PFTB on lipid bilayer integrity. 31P NMR spectra on DOPC MLVs were collected in the absence and presence of different concentrations of the fluoroalcohols. With the addition of HFIP and PFTB, the characteristic bilayer spectrum converts to an isotropic spectrum, indicating a breakdown of bilayer integrity. This is first observed in the spectra recorded at 20–40 mM HFIP or PFTB, and the transition is complete at 200 mM HFIP or PFTB. 70 mM NaNO3, 10 mM HEPES (pH 7.0). To see this figure in color, go online.