Figure 12.

A schematic Jablonski diagram showing targeted photodynamic therapy (tPDT). The method is based on a photosensitizer (PS) attached to a molecule selective for a certain target. The PS is activated by light of a specific wavelength (preferably in the near infrared range, NIR) to a higher-energy state, upon which energy is transferred from the activated PS to surrounding oxygen to form reactive oxygen species (ROS). These can induce irreversible damage to a cell directly or to the tumor-associated vasculature, leading to cell death.