Improved push-pull-push E-Bodipy fluorophores for two-photon cell-imaging

摘要

Quadrupolar Bodipy dyes exhibiting TPA activity and high brightness with an emission at 660 nm were synthesized and internalized in HeLa cells, whereupon FLIM experiments were conducted.rnOptical imaging is one of the most attractive techniques commonly used in biomedical research. Recent progress has raised new demands for dyes with improved properties including good solubility, biocompatibility chemo- and photo-stability, one and two photon excitation, high brightness when internalized into cells, and minimal cytc toxicity. Internalization in cells can be realized by using a vector that facilitates cell entry and may promote selective localization in a given organelle. Alternatively, the chemical structure of the dye can be modified to favour cell penetration. We recently developed a new class of diethynyl dipyrromethene-boron dyes (E-Bodipy) that can be modified at will, and present improved stability without detriment to the optical properties. To extend the development of stable dyes emitting in the 600 to 800 nm range, a window widely recognized as being attractive for bioanalysis and in vivo imaging, we have now developed new dyes emitting around 660 nm as well as being stable (ethynyl substitution at the boron), cell permeable, and having a pronounced internal quadrupole (push-pull-push), a prerequisite for two photon absorption spectroscopy and imaging. We report here the design, the one- and two-photon photophysical properties and the two-photon imaging applications of these improved E-Bodipy fluorophores.