curve. Parameters such as the translational diffusion time, which characterizes
the average residence time of the fluorescent molecule in the defined excitation
volume, and the average number of fluorescent molecules in the volume can then
be determined. FCS has been used to measure the location, accumulation, and
mobility of fluorescently tagged molecules in membranes and the cell wall from
very low-bulk concentrations. Also, fluorescence cross-correlation spectroscopy
(FCCS) has been used to measure protein-to-protein interaction between two
fluorescently tagged targets. The reader is referred to other publications for
a comprehensive review on FCS [98–100].
12.8 Summary of Important Points
1. Fluorescence imaging provides an incomparable degree of flexibility, ...