Significance: Endogenous hypochlorite (HClO), the strong oxidizing and chlorinating species generated by myeloperoxidase, has been speculated to be closely associated with the development of epilepsy. However, direct imaging evidence from live brains with epileptic behaviors is rare. Herein, we have developed a two-photon fluorescence probe for the real-time tracking of endogenous HClO fluxes in vivo and ex vivo in epileptic brains. The application of this probe to construct a high-throughput screening platform would rapidly screen the potential antiepileptic agents to control overexpressing HClO. This work provides a versatile chemical tool for investigating HClO under pathological conditions of epilepsy and could be used to rapidly discover additional antiepileptic agents.

Ferroptosis is an iron-dependent, non-apoptotic form of programmed cell death driven by excessive lipid peroxidation (LPO). Mounting evidence suggests that the unique modality of cell death is involved in the development and progression of several diseases including cancer, cardiovascular diseases (CVDs), neurodegenerative disorders, etc. However, the pathogenesis and signalling pathways of ferroptosis are not fully understood, possibly due to the lack of robust tools for the highly selective and sensitive imaging of ferroptosis analytes in complex living systems. Up to now, various small-molecule fluorescent probes have been applied as promising chemosensors for studying ferroptosis through tracking the biomolecules or microenvironment-related parameters in vitro and in vivo. In this review, we comprehensively reviewed the recent development of small-molecule fluorescent probes for studying ferroptosis, with a focus on the analytes, design strategies and bioimaging applications. We also provided new insights to overcome the major challenges in this emerging field.

Epilepsy is a chronic neurodegenerative disease, and accumulating evidence suggests its pathological progression is closely associated with peroxynitrite (ONOO ⁻ ). However, understanding the function remains challenging due to a lack of in vivo imaging probes for ONOO ⁻ determination in epileptic brains. Here, the first near‐infrared imaging probe (named ONP) is presented for tracking endogenous ONOO ⁻ in brains of kainate‐induced epileptic seizures with high sensitivity and selectivity. Using this probe, the dynamic changes of endogenous ONOO ⁻ fluxes in epileptic brains are effectively monitored with excellent temporal and spatial resolution. In vivo visualization and in situ imaging of hippocampal regions clearly reveal that a higher concentration of ONOO ⁻ in the epileptic brains associates with severe neuronal damage and epileptogenesis; curcumin administration can eliminate excessively increased ONOO ⁻ , further effectively protecting neuronal cells. Moreover, by combining high‐content analysis and ONP, a high‐throughput screening method for antiepileptic inhibitors is constructed, which provides a rapid imaging/screening approach for understanding epilepsy pathology and accelerating antiseizure therapeutic discovery.