Electrorotation: A Spectroscopic Imaging Approach to Study the Alterations of the Cytoplasmic Membrane

Abstract

Electrorotation (ER) is a technique allowing the characterization of the surface properties of a variety of supra-molecular aggregates and living cultured cells as well as cellular organelles and biological materials in general. In particular, this technique allows measuring two important physical parameters of the cell membrane: specific capacitance and specific conductance. These parameters are strictly related to the structure/function relationships of the biological membrane; ER becomes thus a powerful means to investigate a number of phenomena involving the membrane integrity. These phenomena may originate from treatments with exogenous molecules and/or from pathological effects. Concerning these aspects, the study of the transfer of exogenous material (i.e. cat-anionic vesicles or liposomes) across the cell membrane assumes a high importance. This review is focused on the physical functioning principles of ER and on the quantitative analysis of the experimental measurements. This work also reports on different fields of application of ER with particular reference to data obtained in our laboratory. The investigation of the alterations of the cytoplasmic membrane function, as evidenced by this strategy, will be illustrated in detail.