Thermal acoustic radiation in model membranes at phase transition of lipids

The objects under investigation were model membranes, i.e., multilayer liposomes from phospholipids (dimyristoylphosphatidylcholine and dipalmitoylphosphatidylcholine). Thermal acoustic radiation was measured in the megahertz frequency range at phase transitions of lipids from a liquid crystal state to a gel (on cooling) and, vice versa, from a gel state to a liquid crystal (on heating of the liposome suspension). In this case, the intensity of thermal radiation varied, i.e., increased on cooling and decreased on heating. This effect was shown to be related to the increase in absorption in liposomes at the phase transition.