title: Lipid Diffusion in Supported Lipid Bilayers: A Comparison between Line-Scanning Fluorescence Correlation Spectroscopy and Single-Particle Tracking.
abstract: Diffusion in lipid membranes is an essential component of many cellular process and fluorescence a method of choice to study membrane dynamics. The goal of this work was to directly compare two common fluorescence methods, line-scanning fluorescence correlation spectroscopy and single-particle tracking, to observe the diffusion of a fluorescent lipophilic dye, DiD, in a complex five-component mitochondria-like solid-supported lipid bilayer. We measured diffusion coefficients of DFCS ~ 3 um2 * s-1 and DSPT ~ 2 um2 * s-1, respectively. These comparable, yet statistically different values are used to highlight the main message of the paper, namely that the two considered methods give access to distinctly different dynamic ranges: D sup or approximatively 1um2 * s-1 for FCS and D inf or approximatively 5 um2 s-1 for SPT (with standard imaging conditions). In the context of membrane diffusion, this means that FCS allows studying lipid diffusion in fluid membranes, as well as the diffusion of loosely-bound proteins hovering above the membrane. SPT, on the other hand, is ideal to study the motions of membrane-inserted proteins, especially those presenting different conformations, but only allows studying lipid diffusion in relatively viscous membranes, such as supported lipid bilayers and cell membranes.
authors.affiliation: Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada. rosemm2@mcmaster.ca.
authors.forename: Markus
authors.initials: M
authors.lastname: Rose
authors.affiliation: Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada. hirmizn@mcmaster.ca.
authors.forename: Nehad
authors.initials: N
authors.lastname: Hirmiz
authors.affiliation: Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4L8, Canada. mirabj@mcmaster.ca.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Moran-Mirabal
authors.affiliation: Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada. fradin@physics.mcmaster.ca.|Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8N 3Z5, Canada. fradin@physics.mcmaster.ca.
authors.forename: Cécile
authors.initials: C
authors.lastname: Fradin
keywords: FCS; SPT; bilayer; confocal microscopy; diffusion; fluorescence; lipid; membrane; total internal reflection fluorescence microscopy (TIRF)