Non-UV-activated persistent luminescence phosphors for sustained bioimaging and phototherapy

Sustained phototheranostics refers to the continuous diagnostic or therapeutic activity initiated by a single dosage of light stimulation. For instance, many optical agents stimulated by light irradiation can produce long-lived luminescence and continuously release reactive oxygen species (ROS) to realize sustained imaging-guided photodynamic therapy (PDT). Sustained phototheranostics features high spatiotemporal precision, low doses, noninvasiveness, and minimal side effects. Persistent luminescence phosphors (PLPs) can store the excitation energy within crystal defects and slowly release the trapped energy for imaging or therapy, making them particularly suitable for sustained phototheranostics. Whereas, most PLPs are activated by ultraviolet (UV) light, which seriously limits their phototheranostic applications due to the poor tissue penetration ability and photodamage of UV light. During the past years, great efforts have been made in the development of non-UV-activated PLPs, and a series of X/γ-ray or visible/near-infrared (NIR) light-activated PLPs with significantly improved tissue penetration ability have been designed. These non-UV-activated PLPs provide ideal optical agents for sustained phototheranostics. This review summarizes the recently developed non-UV-activated PLPs and the sustained phototheranostic strategies based on these PLPs. This review can provide instructions for the design of non-UV-activated PLPs and further contribute to areas including phototheranostics, photocatalysis, solar cells and LEDs.