Redox-activated photosensitizers for visualizing precise diagnosis and potentiating cancer therapy

Cancer still threats human health rigorously. Most current options of photosensitizers (PSs) are plagued with "always on", accounting for limited signal-to-noise ratio in the lesions and undesired side effects in normal tissues. Inspired by the redox imbalance of tumor microenvironment, redox-activated PSs (RA-PSs) are coming to frontiers that enhance diagnosis accuracy and treatment efficiency. Herein, the progress of PSs-based therapy is outlined. Furthermore, the design strategies of RA-PSs are discussed, including potential mechanism and linkage to obtain on-demand switchable optical signals. Moreover, versatile RA-PSs for real-time visualization and therapy are highlighted. Finally, future prospects and challenges are spotlighted.