Fluorescence imaging to probe mercury induced oxidative stress in living systems

Mercury is known a toxic heavy metal pollutant, and mercuric derivatives severely threaten ecological environment and human health. Their toxicological effects are usually associated with oxidative stress and redox imbalance. However, rare visualized evidences to reveal mercury induced oxidative stress in living systems. According to its characteristics, we suspected mercury resulted in two consequences, one is reactive oxygen species (ROS) outburst, the other is oxygen consumption caused hypoxia stress. Hydrogen peroxide (H2O2) is an important oxygen metabolite, and superfluous H2O2 will attack intracellular antioxidants and trigger oxidative stress, then cause dysfunctions and many diseases. Although the research of H2O2 fluorescence probe has been greatly advanced, the exploration of H2O2 bioeffects under environmental stress was scarce. There is still necessary to develop powerful tools to explore redox homeostasis and H2O2 fluctuations under mercury stress. Herein, we have designed fluorescent probe MSO-Bindol for monitoring H2O2 fluctuations through destruction of carbon-carbon double bond leading to ratiometric fluorescent changes. MSO-Bindol is successfully used to observe H2O2 variations in cells and zebrafish exposed to various stimulations or environmental stress especially mercury stress. Moreover, imaging results provide visualization proofs for Hg2+-mediated H2O2 variations and reveal the relationship between Hg2+-induced oxidative stress and up-regulated H2O2 in biological systems.