Strategies for the development of photodynamic sensitizers

The use of light activated dyes in photomedicine offers the potential to administer to patients an inert compound which can be selectively activated by photoirradiation. Such a process allows for unique control of the photochemotherapeutic process, using techniques to enhance grug targeting and/or selective irradiation of target tissues. Substantial progress has been made in recent years in developing biologically compatible photosensitizers and in understanding their mechanisms of action. In one field of photomedicine called photodynamic therapy, excitation of the sensitizer leads to the generation of activated oxygen species which then oxidize biological substrates such as protein and lipids. Since different sensitizers localize in different cell types and in different subcellular organelles, the mechanisms of cell necrosis may differ. Current research is aimed at better understanding the parameters responsible for these properties of photosensitizers and in expanding the disease indications to which phototherapy can be applied