Synthetic strategies in designing porphyrin-based photosensitizers for photodynamic therapy

Photodynamic therapy (PDT) is a promising cancer treatment that involves the combination of visible light and a photosensitizer. Each factor is harmless by itself, but when combined with oxygen they can produce lethal cytotoxic agents, initially singlet oxygen, that inactivate the tumor cells. This enables greater selectivity toward diseased tissue, as only those cells that are simultaneously exposed to the photosensitizer, light, and oxygen are exposed to the cytotoxic effect. The dual selectivity of PDT is produced by both a preferential uptake of the photosensitizer by the diseased tissue and the ability to confine activation of the photosensitizer to this diseased tissue by restricting the illumination to the specific site.