Mitochondrial viscosity detection using a large stokes shift near-infrared fluorescent probe: An innovative tool for precise monitoring of oxidative stress in stroke and early diagnosis.

Ischemic stroke represents a profound global health burden, with oxidative stress playing a pivotal role in ischemia-reperfusion injury, thereby exacerbating cellular damage and neuronal dysfunction. Viscosity changes in the mitochondrial microenvironment, detectable via fluorescent probes, provide a sensitive biomarker for oxidative disturbances. In this study, we present XZTU-Mito-Vis, a novel near-infrared (NIR) fluorescent probe (λ = 715 nm) with large Stokes shift (Δλ = 290 nm), meticulously designed based on ESIPT (excited-state intramolecular proton transfer) mechanism. This probe not only exhibits exceptional mitochondrial affinity (PCC = 0.91) but also demonstrates a remarkable 418-fold fluorescence enhancement in response to viscosity fluctuations. By finely tuning its hydrophilic-lipophilic balance, XZTU-Mito-Vis effectively traverses the blood-brain barrier, enabling high-resolution, real-time imaging of the brain in vivo. Through rigorous experimental design incorporating both cellular and murine models, the probe elucidates with high precision the spatiotemporal dynamics of oxidative stress, while demonstrating the marked neuroprotective efficacy of apocynin (APO) in mitigating stroke-induced neuronal injury. XZTU-Mito-Vis offers a powerful, versatile platform for precise stroke evaluation, early diagnostic interventions, and targeted neuroprotective therapies, demonstrating substantial promise for future clinical applications.