In vivo imaging of hydrogen peroxide production in a murine tumor model with a chemoselective bioluminescent reporter

Living organisms produce hydrogen peroxide (H₂O₂) to kill invading pathogens and for cellular signaling, but aberrant generation of this reactive oxygen species is a hallmark of oxidative stress and inflammation in aging, injury, and disease. The effects of H₂O₂ on the overall health of living animals remain elusive, in part owing to a dearth of methods for studying this transient small molecule in vivo. Here we report the design, synthesis, and in vivo applications of Peroxy Caged Luciferin-1 (PCL-1), a chemoselective bioluminescent probe for the real-time detection of H ₂O₂ within living animals. PCL-1 is a boronic acid-caged firefly luciferin molecule that selectively reacts with H₂O ₂ to release firefly luciferin, which triggers a bioluminescent response in the presence of firefly luciferase. The high sensitivity and selectivity of PCL-1 for H₂O₂, combined with the favorable properties of bioluminescence for in vivo imaging, afford a unique technology for real-time detection of basal levels of H₂O₂ generated in healthy, living mice. Moreover, we demonstrate the efficacy of PCL-1 for monitoring physiological fluctuations in H₂O₂ levels by directly imaging elevations in H₂O₂ within testosterone-stimulated tumor xenografts in vivo. The ability to chemoselectively monitor H₂O₂ fluxes in real time in living animals offers opportunities to dissect H₂O₂'s disparate contributions to health, aging, and disease.