A ratiometric fluorescent nanoprobe for H 2 O 2 sensing and in vivo detection of drug-induced oxidative damage to the digestive system

Hydrogen peroxide is a biologically important reactive oxygen species (ROS) and plays crucial roles in living organisms. Herein, a FRET-based ratiometric fluorescent probe has been developed for detecting H2O2in vitro and in vivo. In this nanoprobe, carbon dots serve as the energy donor and carrier for the H2O2 recognition element. This nanoprobe exhibits fast-response, low toxicity, high sensitivity (with a detection limit of 0.5 μM) and selectivity towards H2O2 over other reactive oxygen or nitrogen species. The nanoprobe has been successfully applied in the detection of H2O2 in live cells and in zebrafish larvae. By incubating the nanoprobe with zebrafishes, the nanoprobe can be absorbed by the fishes within 1 h and accumulates mainly in the abdominal region. Due to its small size (∼4 nm), the nanoprobe is gradually excreted by zebrafishes without long-term accumulation. Moreover, as the first ratiometric chemoprobe that can detect H2O2in vivo, the nanoprobe has been found capable of detecting and locating endogenous H2O2 in zebrafishes as a result of drug-induced oxidative damage. The successful detection of H2O2 by the nanoprobe in vivo may support its eventual use in clinical applications.