A Multi-Analyte-Responsive, Multi-Organ-Imaging, Dual-NIR-Emissive Fluorescent Probe for Visualizing Pyroptosis-Mediated Hg ²⁺ -Induced Hepatorenal Dysfunction

Mercury ions (Hg 2+ ) are highly toxic heavy metals that are widely distributed in the environment and pose a serious threat to both ecosystems and human health. After entering the body, mercury preferentially accumulates in the liver and kidneys, underscoring the importance of early detection of acute and chronic hepatorenal injuries. Although fluorescent probes have been widely explored for disease diagnosis, most existing systems cannot achieve simultaneous in vivo imaging of the liver and kidneys, nor can they monitor multiple pathological parameters during hepatorenal injury, thus limiting their utility in evaluating Hg 2+ -induced multiorgan damage. In this study, we developed a multifunctional fluorescent probe, VPO, with high sensitivity and good biocompatibility, which can be used to monitor polarity, viscosity, and ONOO – levels in cells. Using VPO, we observed, for the first time, a significant increase in ONOO – during pyroptosis, accompanied by an elevated mitochondrial viscosity and reduced polarity. In addition, VPO successfully enabled the real-time visual monitoring of these changes in mercury-exposed cells, zebrafish, and mice. Moreover, its multiresponsive property enabled the evaluation of the therapeutic efficacy of N -acetylcysteine (NAC) against Hg 2+ -induced hepatorenal injury. NAC alleviated hepatic and renal mitochondrial oxidative stress, as well as pyroptosis-related inflammatory signaling, by reversing Hg 2+ -induced biomarker abnormalities. In summary, these findings demonstrate that VPO provides a comprehensive platform for the early diagnosis, therapeutic evaluation, and mechanistic investigation of mercury poisoning.