Photodynamic therapy with zinc-tetra(p-sulfophenyl)porphyrin bound to cyclodextrin induces single strand breaks of cellular DNA in G361 melanoma cells

The basis of photodynamic therapy (PDT) is the phototoxicity resulting from co-action of light, sensitizer and oxygen. In this study we demonstrate in vitro phototoxicity measurement on G361 cell lines using ZnTPPS4 sensitizer bound to cyclodextrin hpβCD. We have proved its photodamage effect on cancer cell lines in the visible region of spectrum. We used the halogen lamp (24 V/250 W) as a source of radiation. After 24 h incubation of cell cultures with 10 μM ZnTPPS4 and 1 mM cyclodextrine hpβCD, the cells were irradiated for 7.5 min at the total irradiation dose of 12.5 J cm−2. Analysis of DNA damage in the cell line after PDT was proved by comet assay and using inversion fluorescent microscope with image analysis. This treatment method gave rise to DNA damage. The used radiation dose of visible light in the absence of sensitizers does not induce DNA breaks in tumour cells. In conclusion, binding of ZnTPPS4 sensitizer to cyclodextrin hpβCD may improve the efficacy of PDT for the treatment of malign melanoma.