Phosphorescence Lifetime Imaging Microscopy
Measurements: Practical Aspects
- PLIM imaging of an oxygen-sensitive Ru2+-complex in a cockroach’s salivary gland. The image is scanned with the fast axis from up to down and the slow axis from left to right. At certain time points dopamine was added to stimulate the metabolism, which results in a decrease of the oxygen concentration and thereby in an increase of the lifetime of the Ru2+-complex KR341. After washing, the oxygen consumption decreases again as well as the lifetime of the KR341. The process was repeated during the scan. Data and figures reproduced from Jahn et al. Scientific Reports, Vol. 05, 2015, courtesy of Nature Publishing Group.
The characterization of luminescent materials including their luminescence lifetime has played an important role in the field of material science, especially in chemical sensing. Interest in Phosphorescence Lifetime Imaging (PLIM) has been renewed over the past decade with the booming development of Organic Light Emitting Diode (OLED) technology, in which phosphorescent compounds are often a key component.
Analogous to Fluorescence Lifetime Imaging Microscopy (FLIM), the contrast in a PLIM image is based on excited state lifetime differences between individual fluorophores. In life sciences, typical phosphorescent probes include metal ions complexed with organic ligands, which can be used to image oxygen consumption in living tissue or for energy transfer measurements.