Exploiting Molecular Biology by Time-Resolved Fluorescence Imaging

Abstract

Many contemporary biological investigations rely on highly sensitive in vitro assays for the analysis of specific molecules in biological specimens, and the main part of these assays depends on high-sensitivity fluorescence detection techniques for the final readout. The analyzed molecules and molecular interactions in the specimen need to be detected in the presence of other highly abundant biomolecules, while the analyzed molecules themselves are only present at nano-, pico-, or even femtomolar concentration.A short scientific rationale of fluorescence is presented. It emphasizes the use of fluorescent labels for sensitive assays in life sciences and specifies the main properties of an ideal fluorophore. With fluorescence lifetimes in the microsecond range and fluorescence quantum yield of 0.4 some water soluble complexes of Ruthenium like modified Ru(sulfobathophenanthroline) complexes fulfill these properties. They are outstanding fluorescent labels for ultrasensitive assays as illustrated in two examples, in drug discovery and in point of care testing.We discuss the fundamentals and the state-of-the-art of the most sensitive time-gated fluorescence assays. We reflect on how the imaging devices currently employed for readout of these assays might evolve in the future. Many contemporary biological investigations rely on highly sensitive in vitro assays for the analysis of specific molecules in biological specimens, and the main part of these assays depends on high-sensitivity fluorescence detection techniques for the final readout. The analyzed molecules and molecular interactions in the specimen need to be detected in the presence of other highly abundant biomolecules, while the analyzed molecules themselves are only present at nano-, pico-, or even femtomolar concentration.A short scientific rationale of fluorescence is presented. It emphasizes the use of fluorescent labels for sensitive assays in life sciences and specifies the main properties of an ideal fluorophore. With fluorescence lifetimes in the microsecond range and fluorescence quantum yield of 0.4 some water soluble complexes of Ruthenium like modified Ru(sulfobathophenanthroline) complexes fulfil these properties. They are outstanding fluorescent labels for ultrasensitive assays as illustrated in two examples, in drug discovery and in point of care testing.We discuss the fundamentals and the state-of-the-art of the most sensitive time-gated fluorescence assays. We reflect on how the imaging devices currently employed for readout of these assays might evolve in the future.