Photodynamic therapy: photosensitizers and nanostructures

The reactions of some structures to different external stimuli can be used for therapeutic purposes. In particular, in photodynamic therapy (PDT), a light-sensitive compound or structure, commonly named a photosensitizer (PS), is able to produce reactive oxygen species (ROS) after being irradiated with light in the presence of oxygen. Such ROS are effective in destroying cells and can be used as therapeutic agents to treat some skin and eye diseases, as well as certain types of cancer. This review will summarise the current state-of-the-art in PDT, with special focus on the different available photosensitizers, their chemistry, their incorporation into different nanostructures, and some of the current targeting strategies.