In conventional fluorescence microscopy only the information conferred by the fluorescence intensity is exploited. But also other intrinsic properties of a fluorophore such as the fluorescence lifetime can be used to retrieve additional information about the sample. Fluorescence lifetime imaging (FLIM) can report on photophysical events that are too difficult (or impossible) to observe by fluorescence intensity measurements.

Since the lifetime of a fluorophore depends on its local environment it can be used as a sensor for properties of the solvent such as the viscosity and dissolved compounds such as ions or oxygen. By exploiting physical phenomena such as Förster energy transfer (FRET), FLIM can be used to test if molecules are in close vicinity to each other. In this way molecular interactions can be “imaged”.

In the lab of the Biomolecular Photonics Group several methods to measure fluo­res­cence lifetimes are established. One tech­nique is based on time-correlated single photon counting (TCSPC); the other method is based on a streak-camera system. This course will give an introduction into the technical equip­ment necessary to acquire the data and the mathe­matical algorithms used to analyze the data.

Further information about the course can be found on the website of the Biomolecular Photonics group: https://www.uniklinikum-jena.de/photonik/en/Teaching/Summer+School.html   

Setup used for fluorescence lifetime mea­sure­ments. A pulsed Titanium:Sapphire (TiSa) laser or a super­continuum laser are used for pulsed excitation of the biological sample on the stage of a confocal laser scanning microscope. Fluorescence emitted by the sample is recorded with a streak-camera (1) or a fast PMT-array (2) with a high spatial (x,y), temporal (t) and spectral (l) resolution.