Synthetic Wavelength-Shifting Fluorescent Probes of Nucleic Acids

Abstract

Visualizing of nucleic acids represents not only an important task for molecular imaging but also for chemical biology in general. Fluorescent labels can be incorporated either synthetically into nucleic acids by their corresponding building blocks (both phosphoramidites and nucleoside triphosphates) or postsynthetically by one of the recent sophisticating "click"-type reacting building blocks. Herein, we focus on the development of new photostable cyanine-styryl dyes and on wavelength-shifting fluorescent probes as promising tools for molecular imaging. The double helical architecture around two fluorophores is crucial for efficient photophysical interactions that range from excitonic and excimer-type to energy transfer interactions. This is equally important for fluorescent labels as isosteric and non-isosteric DNA base replacements. Especially, the latter ones yield fluorescent DNA and RNA systems with dual emission color readout as wavelength-shifting probes. Our DNA and RNA "traffic light" combines the green emission of TO with the red emission of TR. The concept can be transferred to a DNA system that is synthetically easier to access since the dyes were attached postsynthetically as 20-modifications. Using newly synthesized dyes of the cyaninestyryl type, new nucleic acid probes were realized with high quantum yields and excellent photostability. Combined as energy transfer pairs not only wavelength-shifting DNA probes with red-green-transfer emission color change but also yellow-blue pairs were realized. All of them show good emission color contrasts due to very efficient energy transfer. These wavelength-shifting probes have a significant potential to be applied on the RNA level for molecular imaging of living cells. PU - SPRINGER-VERLAG BERLIN PA - HEIDELBERGER PLATZ 3, D-14197 BERLIN, GERMANY