Following Photofrin, the first generation photosensitizer, several second generation photosensitizers have been
developed with improved characteristics. More recently, third generation photosensitizers are proposed to achieve higher
selectivity toward cancer cells/ tumor tissue. Elevated mitochondrial membrane potential of malignant cells has tested as
a tool for preferential uptake of certain photosensitizers to cancer cells. In the same line, we designed new conjugate
systems where delocalized cationic moiety delivers a photosensitizer to mitochondria. To prove our concept, two
prototype conjugates (TPP-Rh and TPP-AO) were prepared using two cationic dyes (Rhodamine and Acridine Orange)
and a photosensitizer (tetraphenylporphyrin, TPP). The two conjugates generated singlet oxygen quite well.
Interestingly, the two conjugates showed higher cellular uptake by mover than 8 times than TPP-OH as well as higher
phototoxicity. In particular, TPP-Rh showed closer localization pattern to mitochondria than TPP-OH.
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