Monitoring the upregulated hydrogen peroxide levels in cells and living organisms under the microcystin-LR exposure

Microcystin-LR (MC-LR) could be largely released in water environment during the cyanobacterial blooms, endangering the health of plants, animals, and even humans. Numerous evidences had demonstrated a strong correlation between the toxicities of MC-LR and the oxidative stress induced by MC-LR. Hydrogen peroxide (H₂O₂) is one of the primary constituents of reactive oxygen species (ROS) and tends to be overproduced under oxidative stress. Therefore, detecting the changes in H₂O₂ levels in organisms exposed to MC-LR can serve as an indicator of MC-LR-induced oxidative damage. However, the studies of directly detecting H₂O₂ levels in organisms exposed to MC-LR are lacking. In this work, we developed a novel near-infrared probe, DSP-B, to detect H₂O₂ under MC-LR-induced oxidative stress in organisms. DSP-B exhibited high sensitivity and specificity to H₂O₂, and the detection ability of DSP-B to endogenous and exogenous H₂O₂ has also been validated. Then DSP-B was applied to detect the H₂O₂ level in cells and zebrafishes treated with MC-LR to elucidate the effect of oxidative stress caused by MC-LR. Moreover, DSP-B was utilized for tissue visualization imaging in MC-LR-poisoned loaches model, enabling the upregulation of H₂O₂ to be successfully observed. This study offers a novel strategy for analyzing the MC-LR-induced oxidative stress and demonstrates the potential of using probe for MC-LR toxicity research. This probe is expected to provide assistances in evaluating the risks and hazards of MC-LR exposure to organisms in the environment.