In recent years, photodynamic therapy (PDT) has emerged as one of the promising alternative treatment for the management of chronic infection. PDT involves the use of a nontoxic drug or dye known as photosensitizers followed by local illumination with low-intensity visible light (Castano et al., 2004, Huang et al., 2008). Upon absorption of light, the PS becomes activated from its ground state to an excited state and undergo intersystem crossing with oxygen to produce reactive oxygen species (ROS), such as singlet oxygen and free radicals. These ROS mediate cellular toxicity via oxidative stress to cell membranes and other cellular components (Dolmans et al., 2003, Henderson and Dougherty, 1992). Photosensitizers are usually aromatic compounds
