Dyes for use in photodynamic therapy (PDT)
An opportunity to merge our long-standing interest in synthetic dyes with an initial career interest in pharmaceuticals was the inspiration for current research pertaining to the design and synthesis of dye sensitizers for photodynamic therapy (PDT). PDT is a type of photochemotherapy for various types of cancers and requires the presence of light, a sensitizer, and molecular oxygen for treatments. During PDT, a sensitizer is administered intravenously, intraperitoneally, or topically, and selectively localizes in a tumor due to physiological differences between the tumor and healthy tissue. Localization into cancer cells and achieving a maximum tumor-to-normal cell concentration ratio can take 3 to 96 hours, depending on the photosensitizer and tumor. Following localization, fluorescence from the sensitizer can be used to diagnose and detect the tumor. Irradiation at a wavelength specific to the photosensitizer produces singlet oxygen, which reacts with and destroys the tumor. Suitable sensitizers are mainly porphyrinoid compounds, phthalocyanines, and related structures. Our research focuses on the design of novel dyes having high singlet oxygen generating efficiency and high selectivity for tumors. Porphyrin and formazan systems containing appendages that facilitate tumor uptake are currently under investigation (e.g. 7-8).