Chemiluminescent probes in cancer biology

Optical imaging technologies that use fluorescence and chemiluminescence probes allow the real-time detection of biological activity in the context of location, time and environment. Optical imaging is particularly important for the diagnosis and investigation of cancer. Chemiluminescence is based on the production of an electronically excited species from reactants followed by the release of visible light. Unlike fluorescence imaging, chemiluminescence does not require light excitation and is thus not limited by autofluorescence and high background signals. In this Review, we discuss the four main types of chemiluminescent probes, that is, luminol and its derivatives, peroxalate esters, phenoxy-1,2-dioxetanes with light emission through energy transfer and phenoxy-1,2-dioxetanes with direct light emission, highlighting their design, mode of action, compatibility and applications in cancer biology, diagnosis and treatment. We outline how these chemiluminophores can act as single-component probes for the in vivo and in vitro detection and imaging of various analytes and enzymes and highlight applications that may benefit from chemiluminescent imaging probes.