Some Aspects of Excited-State Probe Emission Spectroscopy for Structure and Dynamics of Model and Biological Membranes

Abstract

An overview of some of the techniques by which certain structural (order, organization) and dynamic (fluidity, diffusion) features of simple model and complex biological lipid bilayer membranes can be elucidated by using certain properties of electronically excited states of appropriate probe molecules will be presented. A detailed knowledge of such features may be indispensable to a proper understanding of the function of cell membranes in various regulatory processes and of their dysfunction in pathological states such as cancer. The excited states, created by the absorption of visible or near ultraviolet light, and monitored by the subsequent emission of light quanta at longer wavelengths which takes place in nanoseconds (fluorescence) or micro- to milliseconds (phosphorescence, delayed fluorescence), exhibit reactive, directional and donatory properties which can be utilized to quantitate lateral diffusion, rotational diffusion, orientational order and topographical distribution of the probe, which may or may not be chemically attached to, and thereby reflect the motion or distribution of, another membrane-located molecular or macromolecular species.