Mechanism and design of organic afterglow luminescent probes for cancer theranostics

Organic afterglow luminescent probes (OALPs), characterized by their long-lasting luminescence after irradiation (by light, ultrasound, or X-rays) cessation, are pivotal tools in autofluorescence-free optical imaging. They exhibit ultra-low background noise interference, enhancing imaging sensitivity and ensuring clearer, more reliable imaging results. Moreover, they offer deeper tissue penetration compared to traditional optical imaging modalities, providing various information from deep tissues. Recently developed sonoafterglow and radioafterglow further enhance tissue penetration depth. This review outlines 2 design approaches for OALPs: coencapsulation and conjugation, which are derived from their luminescent mechanism. Guided by these strategies, researchers have designed 3 types of OALPs: near-infrared OALPs, responsive OALPs, and ratiometric OALPs. Additionally, we also provided examples of how OALPs are integrated with therapy and applied in the field of cancer theranostics. Finally, we discuss certain challenges encountered in the advancement of the next generation of OALPs, aiming to broaden their scope of applications.