Effect of Laser Radiation on Free Radicals in Human Cancer G361 Cells

EPR spectroscopy was used to the examination of free radicals evolution in cancer G361 cells during photodynamic therapy. The cancer cells were cultured with photosensitizer ALA and irradiated with 635 nm light by laser. The number of cells was determined microscopically. The decrease in the cell number and the increase in free radicals, obtained for G361 cells cultured with ALA and irradiated with laser, were stronger than relevant changes for the cells which were only irradiated with laser. The studied melanotic cells susceptible for photodynamic therapy differ from the other melanotic SK human cancer cells by fast spin-lattice relaxation processes. Slow spin-lattice relaxation processes exist in the studied earlier non susceptible for photodynamic therapy SK cells.