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Mitochondria are the main sites for the production of hypochlorite (OCl - ). The protein adenine nucleotide translocase (ANT) is located in the inner mitochondria membrane, which is mainly participated in the transportation of ions and metabolites. At the cellular organelle level, overexpression of ANT is associated with enhanced production of OCl - , however, abnormal levels of OCl - cause redox imbalance and loss of function of mitochondria. Herein, a novel mitochondria-targeted ratiometric fluorescent probe Mi-OCl-RP has been developed. Molecular docking calculation suggested a potential molecular target for the probe in the ANT, and the high binding energy (-8.58 kcal mol -1 ) may explain the high mitochondria selectivity of Mi-OCl-RP. The unique probe exhibits excellent spectral properties including ratiometric fluorescence response signals to OCl - (within 7 s), high selectivity and sensitivity, and a large Stokes shift (278 nm). In addition, the colocalization coefficient confirms that Mi-OCl-RP can effectively target mitochondria. Furthermore, Mi-OCl-RP has low toxicity and good permeability, and was successfully employed in ratiometric imaging of OCl - in vivo, affording a robust molecular tool for investigating the biological functions of OCl - in living systems.

The excessive production of sulfur dioxide (SO2) and formaldehyde (FA) by organisms is closely associated with several diseases, including neurological disorders, respiratory disease, and genotoxicity. RNA plays a central role in the expression of genes. However, it is difficult for fluorescent probes to explore the intersecting correlation of SO2 and FA near the nucleolus regions due to the protective obstacle of the cell nucleus membrane. Herein, a unique fluorescent probe (DP) for reversible detection of the interaction of SO2 and FA in the nucleolus regions was constructed. In light of the outstanding attributes of DP, including a large fluorescence ratio variation, ultrafast detection of SO2, and excellent reversibility, it was successfully employed to track the variation of endogenous SO2 and FA in the cytoplasm and nucleolus regions of live cells. In addition, the DP probe could be applied to the imaging of endogenous SO2 and then recovered by FA in live mice.

Graphical abstract A new near-infrared and two-photon fluorescentt probe with a large Stokes shift was engineered to detect SO 2 derivatives in living cells and mice. Highlights • We have developed a novel near-infrared and two-photon ratiometric probe NIR-SO 2 -TP for sensing SO 2. • The new probe NIR-SO 2 -TP exhibited fast response to SO 2 in less than 12 s. • The unique probe NIR-SO 2 -TP exhibited giant stokes shift (185 nm). • The probe NIR-SO 2 -TP showed excellent sensitivity and high selectivity toward SO 2. • The new probe NIR-SO 2 -TP has been successfully applied to sense SO 2 in living cells, tissues, zebrafish and living mice. Abstract As a critical gaseous signaling molecule, SO 2 is involved in multiple physiological and pathological processes. However, the pathogenesis of many serious diseases including lung cancer, cardiovascular diseases and neurological disorders caused by excessive inhalation of SO 2 is still unknown. Hence, the development of reliable analytical methods for efficiently and specifically monitoring SO 2 in living systems is of significance. In this work, a novel near-infrared and two-photon ratiometric fluorescent probe NIR-SO 2 -TP was first proposed for optical SO 2 sensing. The newly synthesized fluorescent probe NIR-SO 2 -TP , which is based on coumarin-benzopyrylium π-conjugated platform, exhibited high selectivity, rapid response time, lower detection limit and a large Stokes shift (185 nm). Importantly, the novel probe has been successfully applied to sense SO 2 in living cells, tissues, zebrafish and living mice at both near-infrared and two-photon modes. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO 2 ), as one of the most dangerous atmospheric pollutants, is associated with several respiratory and neurological diseases. Meanwhile, lysosomes, as scavenger of living cells, play a pivotal role in the metabolic process. However, the pathologic mechanisms of sulfur dioxide at the subcellular level remain elusive in part due to the lack of methods for detecting of SO 2 in the organelles. Accordingly, the study of SO 2 in lysosome is of high interest. Herein, a two-photon fluorescence probe ( Na-SO 2 -Lyso ) for detecting of SO 2 derivatives was developed based on a unique C N isomerization mechanism. The probe Na-SO 2 -Lyso could respond to SO 2 rapidly in less than 15 s with excellent sensitivity. Significantly, Na-SO 2 -Lyso was effectively applied to image of SO 2 in lysosomes of living cells for the first time. Moreover, Na-SO 2 -Lyso also can be used for detecting of SO 2 derivatives in living zebrafish. [ABSTRACT FROM AUTHOR]

Cysteine (Cys), one of cellular biothiols in the organism, is associated with many diseases, such as Parkinson's disease, Alzheimer's disease, liver damage, rheumatoid arthritis, and cancer. However, activatable fluorescence/photoacoustic (FL/PA) probes for non-invasive, real-time, and deep imaging of Cys in vivo are still lacking, and this hinders the diagnosis of Cys-related diseases. Herein, we designed and synthesized a novel activated FL/PA dual-modality cyanine-base probe (FP 700) for real-time detection of Cys. The probe FP 700 was established with near-infrared emissive dye cyanin as the fluorophore, linking with 2, 4-dinitrobenzenesulfonyl group as the recognition moiety for Cys. Using the FP 700 , we found that the FP 700 exhibited intensive "turn-on" FL/PA signals under the excitation of 700 nm, which realized noninvasive in vivo detection of exogenous Cys. Significantly, FP 700 accurately detected endogenous Cys though the FL/PA dual-mode imaging technology in tumor-bearing mice and obtain 3D PA diagnostic images with deep penetration depth and spatial resolution. Thus, the new dual-modality probe FP 700 has advantage of high potential for deep tumor diagnosis of Cys in vivo , which may provide a new approach for the detection of cervical cancer and identification of its potential therapeutic targets. [Display omitted] • The probe FP 700 can recognize exogenous Cys in vitro by fluorescence and photoacoustic signals. • The probe FP 700 achieves non-invasive and real-time monitoring of exogenous Cys level in vivo. • The probe FP 700 can detect endogenous Cys though the FL/PA dual-mode imaging technology in tumor-bearing mice. [ABSTRACT FROM AUTHOR]

Lipid droplets (LDs) are a kind of subcellular organelle, and LDs' polarity is closely associated with the initiation and development of non-alcoholic fatty liver disease (NAFLD). However, due to the lack of robust tools, the evaluation of NAFLD faces the challenge of quantitative diagnosis. Herein, we synthesized a new polarity-sensitive probe CCB , enabling it to quantify the process of fatty liver degeneration in real-time via fluorescence lifetime imaging microscopy (FLIM). The fluorescence lifetime of the probe CCB had a good linear fitting relationship with the polarity, which could be used to quantitatively detect the LDs' polarity via fluorescence lifetime. The robust probe CCB successfully monitored the changes in LDs' polarity via FLIM at cellular and tissue levels in the steatosis process of NAFLD for the first time, which may enlighten to the quantitative diagnosis of NAFLD. [Display omitted] • The fluorescence lifetime of the probe CCB showed a good linear fit with polarity. • CCB successfully achieved the lipid droplets targeting in the cellular and tissue levels. • CCB was applied for the LDs polarity quantitative detection in steatosis via FLIM for the first time. [ABSTRACT FROM AUTHOR]