A Selective, Cell-Permeable Optical Probe for Hydrogen Peroxide in Living

Hydrogen peroxide is a major reactive oxygen species (ROS) in living organisms, and its homeostasis can have diverse physiological and pathological consequences.1 H2O2 is a source of oxidative stress,2 and oxidative damage resulting from cellular imbalance of H2O2 and other ROS oxidants is connected to aging and severe human diseases such as cancer,3 cardiovascular disorders,4 and Alzheimer’s and related neurodegenerative diseases.5 On the other hand, emerging evidence supports a physiological role for H2O2 as a second messenger in cellular signal transduction.6-8 For example, peroxide bursts trigger mitogen-activated protein (MAP) kinase9 and nuclear factor B (NF-B)10 pathways that affect cell prolifera-tion and cell death. Despite the importance of H2O2 to human health and disease, the molecular mechanisms of its production, accumulation, traf-ficking, and function are insufficiently understood even in th