1e:T547,The intracellular viscosity is closely related to many functional disorders and diseases. Especially, abnormal mitochondrial viscosity changes are one of the distinct indications in metabolite diffusion as well as mitochondrial metabolism. In this work, we report a novel fluorescent probe (NI-VIS), which uses quinoline as an acceptor group and employs a TICT mechanism (twisted intramolecular charge transfer) to detect viscosity. NI-VIS features a good mitochondrion targeting ability and near-infrared emission. NI-VIS possesses a highly sensitive response toward viscosity changes in aqueous environments. As the viscosity of a DPBS-glycerol system increased from 1.0 to 999 cP, NI-VIS exhibited a hundred-fold enhancement in fluorescence. We demonstrated that after the treatment with ionophores, NI-VIS could identify the variation of mitochondrial viscosity in HeLa cells. The probe also recognized the decrease of mitochondria viscosity during starvation-induced mitophagy. More importantly, NI-VIS was successfully applied to visualize the viscosity variation in cirrhotic liver tissues. Our trial with zebrafish suggested this probe could map the microviscosity in vivo. These findings reveal that NI-VIS can serve as a powerful tool to monitor viscosity of biological samples and shows broad potential applications in the biomedical field.1f:T4bf,Drug-induced liver injury (DILI) is considered gradually as a serious public health issue, and hepatotoxicity has been regarded as the main clinical problem caused by it. We suspected that both the intracellular viscosity and peroxynitrite (ONOO^-) levels in drug-induced hepatotoxicity tissue are higher than those in a healthy liver. For this reason, we have presented a fluorescent probe VO for multichannel imaging viscosity and ONOO^- simultaneously. Experimental results showed that VO has satisfactory detection performance for both viscosity and ONOO^-, and based on the advantages of its lower cytotoxicity and pH-stabilities, VO was successfully employed to image viscosity and ONOO^- in living cells and animals. More importantly, we use the probe to successfully showcase drug-induced hepatotoxicity by imaging viscosity and ONOO^- induced by acetaminophen (APAP). All the results indicate that VO has great potential for the detection of viscosity and ONOO^- and to assay drug-induced hepatotoxicity. Overall, this work offers a new detection tool/method for a deeper understanding of drug-induced organism injury.20:T48b,Mitochondria-lysosome interactions are essential for maintaining intracellular homeostasis. Although various fluorescent probes have been developed to visualize such interactions, they remain unable to label mitochondria and lysosomes simultaneously and dynamically track their interaction. Here, we introduce a cell-permeable, biocompatible, viscosity-responsive, small organic molecular probe, Coupa, to monitor the interaction of mitochondria and lysosomes in living cells. Through a functional fluorescence conversion, Coupa can simultaneously label mitochondria with blue fluorescence and lysosomes with red fluorescence, and the correlation between the red-blue fluorescence intensity indicates the progress of mitochondria-lysosome interplay during mitophagy. Moreover, because its fluorescence is sensitive to viscosity, Coupa allowed us to precisely localize sites of mitochondria-lysosome contact and reveal increases in local viscosity on mitochondria associated with mitochondria-lysosome contact. Thus, our probe represents an attractive tool for the localization and dynamic tracking of functional mitochondria-lysosome interactions in living cells.21:T430,The measurement of physicochemical parameters in living cells can provide information on individual cellular organelles, helping us to understand subcellular function in health and disease. While organelle-specific chemical probes have allowed qualitative evaluation of microenvironmental variations, the simultaneous quantification of

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