Photosensitizer

Patent Granted In air and tissue, molecular oxygen occurs in a triplet state, whereas almost all other molecules are in a singlet state. Reactions between these are forbidden by quantum mechanics, thus oxygen is relatively non-reactive at physiological conditions. A photosensitizer is a chemical compound that can be promoted to an excited state upon absorption light and undergo intersystem crossing with oxygen to produce singlet oxygen. This species rapidly attacks any organic compounds it encounters, thus being highly cytotoxic.