Evaluation of the Hardness of Lipid Bilayer Membranes of Liposomes by the Ultrasound Attenuation Method

Abstract

We attempted to evaluate the hardness of lipid bilayer membranes of liposomes by an ultrasound attenuation method and compared the results with these obtained by a representative fluorescence probe method using pyrene. We used multilamellar vesicles type of liposomes prepared by Bangham’s method. In the ultrasound attenuation method, the measurement of the ultrasonic attenuation constant of liposomes dispersions indicated that the hardness of the bilayer membranes of the liposomes increased with the increasing cholesterol concentration and the decreasing temperature. This tendency was identical with that found in the results obtained by the fluorescence probe method using pyrene. Therefore, we consider that the ultrasound attenuation method is useful for estimating the hardness of lipid bilayer membranes of multilamellar vesicles type of liposomes.