Detection of Reactive Oxygen Species in Live Cell Mitochondria

Oxidative stress in mitochondria has received intensive attentions recently because it is the most important source of intracellular reactive oxygen species (ROS) and is considered as a major contributor to some public health-related diseases, such as asthma, atherosclerosis, diabetic vasculopathy, osteoporosis, a number of neurodegenerative diseases and Down's syndrome. However, the existing probes have difficulties to target live cell mitochondria and distinct the individual ROS.We have developed a new family of mitochondrial ROS fluorescence probes, which not only can specifically localize in mitochondria, but also can selectively detect the different ROS species, including superoxide, hydroxyl radical and hydrogen peroxide in multiple Ex/Em wavelengths channels.Cancer cells stained with the novel fluorescent probes showed negligible fluorescence in absence of ROS stimulants. In contrast, OxiVision Blue-loaded cells with hydrogen peroxide treatment displayed strong blue fluorescence in mitochondria. MitoROS OH580-loaded cells with Fenton reaction (to induce hydroxyl radical) showed strong red fluorescence in mitochondria. MitoROS 520-loaded cells exhibited strong green fluorescence in mitochondria after treated with superoxide stimulants. All these probes have also been successfully used with a flow cytometer for the quantitative detection of ROS in live cells.In conclusion, these probes are mitochondrion-targeted ROS probes, which can be used for monitoring the exogenous and endogenous changes of ROS levels in living cells in real time by fluorescence imaging and or with a flow cytometer.