Small-molecule fluorescent probes for detecting hydrogen peroxide in biological systems

Hydrogen peroxide (H₂O₂) is a pivotal member of the reactive oxygen species and an essential signaling molecule that participates in numerous biological activities. Abnormal variations in H₂O₂ levels are associated with some certain symptoms and diseases, such as liver injury, Alzheimer's disease, Parkinson's disease, and cancer. To date, small-molecule fluorescent probes have been regarded as powerful tools for monitoring changes in intracellular reactive molecules. Therein, masses of H₂O₂-responsive small-molecule fluorescent probes have been widely constructed and used to investigate the dynamic changes, distributions and important roles and functions of H₂O₂ in living systems. To provide a comprehensive understanding of the characteristics of these reported small-molecule fluorescent probes, this review summarizes their design strategies, detection mechanisms, biological applications, and contributions to pathogenesis exploration. Importantly, we aim for this review to contribute to the development of a new generation of high-quality fluorescent probes for monitoring H₂O₂ fluctuations in biological systems.