A PET-activated photosensitizer based on ROS-sensitive Trolox for tumor microenvironment-responsive imaging and therapy

), oxidize the chromanol ring, therefore deactivating PET and restoring both fluorescence and photosensitizing activity. EtNBS-2C-Tro enables NIR fluorescence imaging of endogenous ROS in tumor-bearing mice and demonstrates potent tumor inhibition with minimal side effects.