Fluorescence lifetime imaging microscopy: spatial resolution of biochemical processes in the cell

Flourescence lifetime imaging microscopy (FLIM) is a technique in which the mean fluorescence lifetime of a chromophore is measured at each spatially resolvable element of a microscope image. The nanosecond excited-state lifetime is independent of probe-concentration or light path length but dependent upon excited-state reactions such as fluorescence resonance energy transfer (FRET). These properties of fluorescence lifetimes allow exploration oft-he: molecular environment of labelled macromolecules in the interior of cells. Imaging of fluorescence lifetimes enables biochemical reactions to be followed at each microscopically resolvable location-within the cell.