Hydrogen peroxide (H2O2) is the principal member of reactive oxygen species (ROS) generated from phagocytic respiratory bursts and mitochondria electron transport chains, which are the major sources of intracellular H2O2 production.1 As a molecule linked to aging, disease and signal-transduction pathways in living organisms,2 H2O2 in high concentrations results in oxidative damage, leading to diseases such as cancer, neurodegenerative Alzheimer's and Parkinson's diseases.3 However, at relatively low physiological levels, H2O2 can act as a classical intracellular signaling molecule mediating cell proliferation, migration and other physiological processes through regulating kinase-driven pathways.4 This dual role of intracellular H2O2 might be used for the diagnosis and treatment of diseases and for drug-toxicity testing.5 However, low concentrations and short lifetimes hamper the detection of H2O2 in living system.6 Fluorescence imaging is a highly sensitive, real-time analytical method for monitoring proceedings in intact cells or tissues.7 Particularly, ratiometric fluorescent probes allow a ratio of the fluorescence intensities at two wavelengths, which is independent of the excitation intensity, emission collection efficiency, sample thickness, and probe concentration, and turns out to be an accurate and efficient method for the intracellular detection of H2O2.8 Although these small-molecule ratiometric fluorescent probes are sensitive and capable of targeting specific labeling, the poor solubility, weak photostability and low quantum yield in aqueous media hamper their application in bioimaging.

A ratiometric, multifunctional nanoprobe was prepared consisting of a self-assembled polymeric micelle as the carrier, tetraphenylethene (TPE) as the donor, fluorescent boronate as the H2O2-responsive acceptor, and triphenylphosphonium as a mitochondria-targeted moiety. The assembled nanoparticles could detect both exogenous and endogenous mitochondrial H2O2 changes in living cells.

Chemical Communications, 2015