Provided herein is a two-component photosensitizer, which demonstrated robust and selective killing effects for transfected HEK cells and affibody targeted A431 cancer cells when exposed to near infrared light excitation. Free MG2I is a pure and stable fluorogen； it is easy to synthesize and modify, and has no toxicity to cells. Unlike conventional photosensitizers, the dye and FAP itself has no photosensitizing effect until they are bound. Also unlike other activation methods, the activation step is achieved by adding the fluorogen, not the presence of the targeted molecule, requiring an ‘；active’； activation instead of a ‘；passive’； activation. This method offers the ability to locally switch-on and selective generation of singlet oxygen at the target site and can be used for a wide variety of molecular targets.
