BODIPY series

FRET probes have not only been generated to measure the phospholipase activity but to study its substrate specificity as well. Several substrates of PLA2 with a variety of head groups and labeled with a BODIPY dye and a Dabcyl quencher were created by Rose et al. and tested against different PLAs in cells to determine substrate specificity and intracellular localization [137], The specificity of PLA2 isoforms towards the number of double bonds in the sn2 position was evaluated with a small series of PENN derivatives. It was demonstrated that the cytosolic type V PLA2 preferred substrates with a single double bond [138],... 

As we will see, the choice of electron donors associated with porphyrins has not evolved much over the years. In previous review articles, electron donors such as carotenes, aryl amines, and ferrocene derivatives have been examined. Concerning the class of energy donors, over the past decade, boron dipyrylmethanes (BODIPY) are probably the most widely used series of compounds. A very detailed study of their association and their excitation energy transfer to porphyrins has been carried out by LindseyIt should be noted that condensed aromatics such as anthracene, and especially perylene derivatives, may be good substitutes for BODIPYs. 

With the same mechanism, a series of unique, acidic pH-sensitive fluorescence probes have been eonstructed for bioimaging viable cancer eells (Scheme 7.9). All these bear various anilines at the meso-position of the BODIPY fluorophore. Similarly, they are almost non-fluorescent in the non-protonated form due to the efficient PET from the aniline moiety to the BODIPY fluorophore. In contrast, they are protonated in acidic medium, and become highly fluorescent, along with a 300-fold increase in emission. With these promising features in hand, fluorescence turn-on probe-antibody eonjugates have been successfully exploited in specific imaging of viable eaneer eells. 

Another series of earlier inaccessible BODIPY fluorophores (Table 2.18), which intensively fluoresce at 601-606 nm (quantum yield is up to 0.95) [227], has been synthesized from pyrroles bearing polycondensed aromatic substituents in position 2 of the pyrrole ring and mesitylaldehyde (Scheme 2.186). 

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