Photodynamic therapy (PDT) is a comparatively novel therapeutic method involving a safe light source and a light-sensitive substance, termed as photosensitizers (PSs), such as methylene blue (MB), toluidine blue (TBO), sulfonated aluminum phthalocyanine, chlorine derivatives, nontoxic indocyanine green (ICG), and curcumin (CUR). (1) The combination of a nontoxic PS with low-intensity visible light in the presence of oxygen develops reactive oxygen species (ROS) that are toxic and can cause oxidative damage to microorganisms and tumor cells. (2-4) PSs do not induce cytotoxicity but are activated by laser irradiation at a proper wavelength and develop ROS. (5,6)