SINGLET OXYGEN QUANTUM YIELDS OF PORPHYRIN-BASED PHOTOSENSITIZERS FOR PHOTODYNAMIC THERAPY

The major cytotoxic agent with most current photosensitizers used in photodynamic therapy (PDT) is widely believed to be singlet oxygen (1O2). Determination of the 1O2 quantum yields for porphyrin-based photosensitizers, including hematoporphyrin derivative (HiPorfin), hematoporphyrin monomethyl ether (HMME) and photocarcinorin (PsD-007) in air-saturated dimethylformamide (DMF) solutions were performed by the direct measurement of their near-infrared luminescence. In addition, 1O2 quencher sodium azide was employed to confirm the 1O2 generation from the investigated photosensitizers. The maximal 1O2 luminescence occurs at about 1280 nm with full width at half maximum of 30 nm. The 1O2 quantum yields were found to be 0.61 ± 0.03, 0.60 ± 0.02 and 0.59 ± 0.03 for HiPorfin, HMME and PsD-007, respectively. These results provide that these porphyrin-based photosensitizers produce 1O2 under irradiation, which is of significance for the study of their photodynamic action in PDT.