Cell Membrane-Targeted Near-Infrared Fluorescent Probe for Dynamic Visualization of Brain Nitric Oxide in Epilepsy

Nitric oxide (NO) is a key signaling molecule for oxidative stress during epilepsy, and its in situ detection in the brain is crucial. For this purpose, a panel of NO-responsive fluorescent probes (B-NH, MB-NH, FMB-NH, TMB-NH) was prepared based on BODIPY fluorophores in this work. By regulating the calculated log P (clog P), the probe MB-NH (clog P = 2.09) was found not only to show excellent cell membrane targeting but also good blood-brain barrier (BBB) penetration ability, enabling in situ detection of NO in the brain at the cell membrane level. MB-NH exhibits high selectivity, excellent sensitivity (detection limit: 10 nM), and rapid (<10 s) activation of near-infrared fluorescence changes toward NO. MB-NH also has good biocompatibility, long-term (at least 3 h) cell membrane anchoring, and can sensitively detect NO level changes on the cell membrane. More importantly, MB-NH successfully achieved in situ brain imaging and captured abnormal upregulation of NO signaling in the brains of epileptic mouse models. With its excellent cell membrane targeting and in situ brain imaging capabilities, MB-NH can serve as an ideal tool for exploring the visualization of NO in epilepsy and provide technical support for the diagnosis of epilepsy and evaluation of the efficacy of antiepileptic drugs.