Fluorescence lifetime based bioassays

Fluorescence lifetime (FLT) is a robust intrinsic property andmaterial constant offluorescentmatter. Measuring this important physical indicator has evolved from a laboratory curiosity to a powerful and established technique for a variety of applications in drug discovery,medical diagnostics and basic biological research. This distinct trendwasmainly driven by improved andmeanwhile affordable laser and detection instrumentation on the one hand, and the development of suitable FLT probes and biological assays on the other. In this process two essential working approaches emerged. Thefirst one is primarily focused on high throughput applications employing biochemical in vitro assays with no requirement for high spatial resolution. The second evenmore dynamic trend is the significant expansion of assaymethods combining highly time and spatially resolved fluorescence data by fluorescence lifetime imaging. The latter approach is currently pursued to enable not only the investigation of immortal tumor cell lines, but also specific tissues or even organs in living animals. This review tries to give an actual overview about the current status of FLT based bioassays and the wide range of application opportunities in biomedical and life science areas. In addition, future trends of FLT technologies will be discussed.