Nanoencapsulation Method for High Selectivity Sensing of Hydrogen Peroxide inside Live Cells

Reactive oxygen species (ROS) are ubiquitous in life and death processes of cells (Finkel, T.; Holbrook, N. J. Nature 2000, 408 (6809), 239-247), with a major role played by the most stable ROS, hydrogen peroxide (H2O2). However, the study of H2O2 in live cells has been hampered by the absence of selective probes. Described here is a novel nanoprobe (nanoPEBBLE) with dramatically improved H2O2 selectivity. The traditional molecular probe, 2',7'-dichlorofluorescin (DCFH), which is also sensitive to most other ROS, was empowered with high selectivity by a nanomatrix that blocks the interference from all other ROS (hydroxyl radical, superoxide, nitric oxide, peroxynitrite, hypochlorous acid, and alkylperoxyl radical), as well as from enzymes such as peroxidases. The blocking is based on the combination of multiple exclusion principles: time barrier, hydrophobic energy barrier, and size barrier. However, H2O2 sensitivity is maintained down to low nanomolar concentrations. The surface of the nanoprobe was engineered to address biological applications, and the power of this new nanoPEBBLE is demonstrated by its use on RAW264.7 murine macrophages. These nanoprobes may provide a powerful chemical detection/imaging tool for investigating biological mechanisms related to H2O2 or other species, with high spatial and temporal resolution.