ABSTRACT
Among the emerging cancer therapy methods, photodynamic therapy (PDT) is an improvement on the traditional methods (surgery, chemotherapy, and radiotherapy) because it is noninvasive in nature and has some selectivity for cancerous tissue compared with normal tissue (Spikes, 1997; Dolmans et al., 2003). ree key components are involved in the PDT process: photosensitizer (PS), light, and oxygen. In PDT, cancerous cells are locally killed by reactive oxygen species, mostly by the singlet oxygen produced by the PS under illumination and in the presence of oxygen. Aer injection into the organism, the PS selectively accumulates in the cancerous tissue, and a carefully regulated light dose at a selected wavelength initiates the photosensitization reaction that destroys the cancerous tissue (Figure 10.1). Activatable PSs, such as porphyrins, chlorins, phthalocyanines, and bacteriochlorin derivatives, have been demonstrated to possess simultaneous cancer imaging and therapy capabilities, and some of these PSs have been approved for clinical use (Lovell et al., 2010).
