“…7 In contrast, "activatable probes" with "turn-off/on" signals at target sites display improved sensitivity and specificity for real-time imaging of target biomolecules in vivo. [8][9][10][11] Till now, numerous stimuli have been employed to develop activatable probes, including exogenous stimuli (e.g., ultrasound, light, heat, magnetic field) or endogenous stimuli (e.g., enzymes, acidity, glutathione (GSH), reactive oxygen species (ROS)). 12,13 Since many disease-related biomarkers are also detectable in normal tissues or plasma, a single parameter to stimulate probe activation for disease diagnosis might cause "false-positive" results.…”