Trehalose and dry dipalmitoylphosphatidylcholine revisited

Dry mixtures of sonicated vesicles of DPPC and trehalose which contained a maximum of 0.2 mol water/mol lipid were examined by differential scanning calorimetry, Fourier transform infrared spectroscopy and freeze-fracture electron microscopy. Samples of dry DPPC and trehalose prepared from aqueous solution had a minimum Tm of 24 degrees C for the gel to liquid-crystalline transition provided that the vesicles were dried with trehalose while the lipid was in liquid-crystalline phase. This low transition is compared to a transition of 105-112 degrees C for dry pure DPPC and of 42 degrees C for hydrated pure DPPC. The present work is an extension of earlier work from this laboratory using both other lipids and other methods of preparation.