Lambert Instruments

Instead of using FLIM to report FRET, FLIM can also be used for other experiments . Whereas fluorescence lifetimes are mostly independent of the local probe concentration and photobleaching, they can depend on several other factors inside cells.

For instance, the fluorescence lifetime can depend on the environment surrounding the fluorophore and can therefore be used to report on this environment. This dependence varies between different fluorophores and is also dependent on factors like the refractive index.
Another factor that can be imaged by FLIM is the concentration of oxygen. Oxygen is a quencher of fluorescence, so it will decrease the quantum yield of fluorophores and thus affects the lifetime of fluorescent material. As FLIM maps the lifetime with the spatial distribution in one image, it can be detected where in your sample high or low concentrations of oxygen are present. The larger the fluorescence lifetime of the fluorophore (luminophores have lifetimes of more than 800 microseconds), the higher is the sensitivity for oxygen.
The FLIM method also provides chemical imaging of intracellular ions. Many fluorophores are available whose lifetimes are influenced by the presence of ions such as Ca2+, Mg2+, Cl-, H+ or K+, to name a few.