Xanthene-based fluorescence probes with high signal-to-noise ratios are highly useful for bioimaging. However, current strategies for improving the signal-to-noise ratios of xanthene fluorescence probes based on the replacement of oxygen group elements and extension of conjugation always require complicated modifications or time-consuming synthesis, which unfortunately goes against the original intention owing to the alteration of the parent structure and outstanding properties. Herein, a facile strategy is presented for developing a unique class of high signal-to-noise ratio probes by modifying the 2′ position of a rhodol scaffold with different substituents. Systematic studies have shown that the probe named Rhod-CN-B with a strong electron-withdrawing methylene malononitrile functional group (−CH(CN)2) at the 2′ position displayed a high signal-to-noise ratio and excellent photostability in aqueous solutions and could detect peroxynitrite (ONOO–) without interference from other biologically active species. In addition, the excellent selectivity and sensitivity of Rhod-CN-B displayed satisfactory properties in tracking the endogenous production of ONOO– in the apoptosis process of liver cells stimulated by lipopolysaccharides. Moreover, we utilized Rhod-CN-B to perform imaging of ONOO– in the course of the liver ischemia/reperfusion (I/R) process, revealing that high ONOO– levels were associated with aggravation of hepatocyte damage. All of the experimental data and results demonstrated that Rhod-CN-B could be a powerful tool for imaging ONOO– in more physiological and pathological processes.

Background and Objective: Hepatic ischemia-reperfusion injury (HIRI) results in serious complications after liver resection and transplantation. Edaravone (ED) has a protective effect on IRI. This study was designed to evaluate whether ED could protect the liver of rats from HIRI injury and explored its exosomal miRNA-related mechanism. Methods: The sham group, hepatic ischemia/reperfusion (IR group), and hepatic ischemia/reperfusion + edaravone (ED group) models were established. We determined the protective effect of ED by measuring alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), superoxide dismutase (SOD); enzyme-linked immunosorbent assay for tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β); hematoxylin-eosin staining and immunohistochemistry for histopathological changes. Exosomal miRNAs were subjected to second-generation sequencing to identify their differential expression. The results were analyzed using bioinformatics methods and validated using real-time quantitative polymerase chain reaction (RT-qPCR). Results: HIRI rats showed higher levels of ALT, AST, oxidative stress, and inflammatory markers; ED attenuated these effects. The sequencing results showed 6 upregulated and 13 downregulated miRNAs in the IR vs. sham groups, 10 upregulated and 10 downregulated miRNAs in the ED vs. IR groups. PC-3p-190-42101 was screened as an overlapping differentially expressed miRNA, and RT-qPCR validation showed that its expression in HIRI rats was significantly decreased; ED prevented this downregulation. Moreover, the expression of PC-3P-190-42101 was significantly correlated with the level of inflammatory factors. Conclusion: These findings indicate that ED can regulate the level of inflammatory factors by affecting the expression of miRNA PC-3p-190-42101 in plasma exosomes to protect the liver from IRI.