Fluorescence Correlation Spectroscopy of Lipid Membranes

Introduction

Fluorescence correlation spectroscopy (FCS), along with fluorescence recovery after photobleaching (FRAP) and single particle tracking (SPT), belongs among the most important techniques for investigating molecular diffusion in biological systems, including lipid membranes. FCS extracts information on the kinetics of molecular movements and chemical reactions from the analysis of fluctuations in fluorescence intensity collected from a small observation volume. When applied to study mobility of molecules in biological membranes and their artificial models, it has to be adapted to the slow mobility of membrane components and the locally planar geometry. In biological membranes, their highly inhomogeneous structure ought to be considered as well. According to current models, cell membranes contain nanoscopic domains differing in composition and mechanical properties from their surroundings. Furthermore, interaction with cytoskeleton forms semipermeable barriers to membrane...