Definition:

Photosensitizer (PS) is usually encapsulated in nanoparticulate formulations (such as liposomes) and also can be chemically conjugated with various nanocarriers to improve their in vivo performance. PSs can be preferentially localized in malignant tissues, and when are activated with appropriate wavelength of light, they can pass on their excess energy to surrounding molecular oxygen, resulting in the generation of Reactive oxygen species (ROS) such as free radicals and singlet oxygen (O2), which are toxic to cells and tissues. PS can be used for Photodynamic therapy (PDT) of cancer.