A ratiometric fluorescent nanoprobe for H₂O₂ 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.