No abstract

Among the pathways for improving the practice of photodynamic therapy of cancer, increasing the selectivity of photodynamic action is an obvious choice. Considering the different characteristics of mitochondria in normal cells and cancer cells, we designed mitochondria‐targeting photosensitizers. We now demonstrate for the first time that mitochondria‐targeted photosensitizers by triphenylphosphonium (TPP) derivatization are more selective for cancer cells compared to normal cells, presumably due to the larger membrane potential of cancer‐cell mitochondria allowing more efficient accumulation of the photosensitizer.

Singlet oxygen, which is stored in the form of an endoperoxide, released under hypoxic conditions typically prevalent in most tumors.

Chemical generation of singlet oxygen under biologically relevant conditions is very important, considering the role played by singlet oxygen in cancer therapeutics. We now demonstrate that a luminol derivative can be chemically excited and transfer the excitation energy to the covalently attached photosensitizer derived from erythrosin. A photosensitizer module, when excited in this manner, can generate singlet oxygen in solution. As hydrogen peroxide is present in a relatively high concentration in cancer cells, singlet oxygen generation through chemical excitation may evolve into an important therapeutic approach.

Addition of fluoride ions switches on the release of singlet oxygen, by removing a steric stopper.