FTIR spectroscopic features of lyotropically induced phase transitions in phospholipid model membranes

Fourier-transform infrared (FTIR) spectroscopy was used to probe the effect s of hydration on phospholipids arranged in multilayer films at room temper ature. In 1-palmitoyl, 2-oleoylphosphatidylcholine (POPC) and 1,2-dioleoylp hosphatidylethanolamine (DOPE), lyotropic phase transitions could be detect ed and assigned to chain melting and to a P-alpha-H-1I transition involving non-lamellar structures, respectively. From a methodological point of view , lipid phase transitions like those are indicated in two different ways: ( i) by drastic, abrupt changes of the indicative parameters, and, (ii), by h ystereses found when non-equilibrium hydration/dehydration scans are run in stead of performing the isopiestic experiments. (C) 1999 Elsevier Science B V. All rights reserved.