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The development of efficient fluorescence-based detection tools with high contrast and accuracy in cancer diagnosis has recently attracted extensive attention. Changes in the microenvironments between cancer and normal cells provide new biomarkers for precise and comprehensive cancer diagnosis. Herein, a dual-organelle-targeted probe with multiple-parameter response is developed to realize cancer detection. We designed a tetraphenylethylene (TPE)-based fluorescent probe TPE-PH-KD connected with quinolinium group for simultaneous detection of viscosity and pH. Due to the restriction on the double bond's rotation, the probe respond to viscosity changes in the green channel with extreme sensitivity. Interestingly, the probe exhibited strong emission of red channel in acidic environment, and the rearrangement of ortho-OH group occurred in the basic form with weak fluorescence when pH increased. Additionally, cell colocalization studies revealed that the probe was located in the mitochondria and lysosome of cancer cells. Following treatment with carbonyl cyanide m -chloro phenylhydrazone (CCCP), chloroquine, and nystatin, the pH or viscosity changes in the dual channels are also monitored in real-time. Furthermore, the probe TPE-PH-KD could effectively discriminate cancer from normal cells and organs with high-contrast fluorescence imaging, which sparked more research on an efficient tool for highly selectively visualizing tumors at the organ level. [Display omitted] • A novel TPE-based fluorescent probe for detection of pH/viscosity in dual channels was developed. • Probe could monitor pH/viscosity fluctuation upon stimulation with CCCP, chloroquine and nystatin. • Probe could distinguish tumor and normal cells and tissues in high contrast by fluorescent imaging. [ABSTRACT FROM AUTHOR]

Biothiols play an important role in cell protein metabolism and signal transduction, especially Hcy was considered as a new risk factor closely related to many diseases. However, there remain some limitations in selectively detecting Hcy due to its structural similarity to Cys. It is urgent for us to develop a novel indicator to study the pathological process of Hcy. Herein, we constructed a new fluorescent probe TCF-SBD composed of tricyanofuran fluorophore and SBD reaction site for detecting Hcy. The probe TCF-SBD exhibited a strong yellow emission response to Hcy in an "off-on" manner, and showed good selectivity for Hcy over Cys and GSH. The sensing mechanism was confirmed by HPLC, NMR titration and DFT studies. The probe was sensitive to the detection of Hcy with LOD low to 0.23 μM. The powerful probe TCF-SBD succeeded in real-time and selectively visualizing Hcy in living cells. [Display omitted] • Fluorescence probe based on substitution-rearrangement process was synthesized for selective detection of Hcy. • The probe displayed high selective and sensitive for Hcy (detection limit is 0.23 μM). • The probe was applied for fluorescence imaging of exogenous Hcy in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple naphthalimide-based chemosensor was synthesized based on ICT process for ratiometric detection of SO 2 derivatives. • The probe displayed high selective and sensitive for derivatives (detection limit is 1.53 μM). • The probe was applied for exogenous and endogenous SO 2 imaging by dual emission channels in living Hela and HepG2 cells. SO 2 is a well-known signal molecule and one of reactive sulfur species, which closely participates in many metabolic processes. While unbalanced metabolism of sulfur dioxide can lead to serious complications of various diseases. Therefore, a rapid and accurate monitoring of SO 2 derivatives with high selectivity and sensitivity would be beneficial for their bio-analytic studies. Herein, a novel ratiometric fluorescent probe (NG-TCF) based on ICT mechanism for monitoring SO 2 was developed. The probe underwent a nucleophilic addition of HSO 3 -/SO 3 2- to give rise to a 120 nm blue-shift dual-emission signal changes in enhanced green channel and subdued red channel under a single wavelength excitation. The probe showed fast response rate (within 7 min), good sensitivity (the detection limit is 1.53 µM), and specific response toward HSO 3 -/SO 3 2- over other bio-species, including H 2 S and ClO-. Moreover, the probe can be applied for visual ratio imaging of exogenous and endogenous SO 2 derivatives in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple flavone-based chemosensor was synthesized based on ESIPT process for ratiometric detection of hydrogen polysulfides. • The probe displayed high selective and sensitive for hydrogen polysulfides (detection limit is 0.63 μM). • The probe was successfully applied to exogenous H 2 S n detection and imaging by dual emission channels in living Hela cells. Hydrogen polysulfides (H 2 S n) as an important member of reactive sulfur species is closely relevant to many physiological functions in redox homeostasis and metabolism. Dual-channel monitor the changes of H 2 S n level in vivo is highly desired. Herein we design a simple ratiometric fluorescent probe based on flavone skeleton for highly selective detection of H 2 S n. The probe HF-NA-MC bearing 2-fluoro-5-nitrobenzoic acid group inhibited the intramolecular ESIPT process, which show the blue fluorescence of adjacent naphthalene unit. In the presence of H 2 S n , the enol form of probe is converted to conjugated keto form, resulted in a 90 nm red-shift of fluorescence emission from 450 nm to 540 nm. The ratiometric intensity (I 540 /I 450) of the probe exhibits a good linear relationship toward H 2 S n in the range of 0–120 μM, and the detection limit is estimated to be 0.63 μM. The ratiometric fluorescent probe shows high specificity and anti-interference ability for H 2 S n over other related reactive sulfur species. The probe HF-NA-MC shows promising outlook and could be applied to the confocal imaging of H 2 S n by dual emission channels in Hela cells. [ABSTRACT FROM AUTHOR]

Understanding lysosome-related physiology needs specific lysosome probes to track the biological processes of lysosome in living cells. Here, we report an azacyclo-modified fluorescent probe that has a large Stokes shift, good photostability and negligible cytotoxicity for highly specific labeling of lysosome and autolysosome in living cells. The probes with different kinds of azacyclo groups on parent dye dansyl are screened to show that dansyl-cycleanine (DNS-C) with four nitrogen atoms possesses the best lysosome-localized ability. And DNS-C as a universal tracker exhibits excellent ability for lysosome labeling in different cell lines with high overlap coefficients (≥0.90). Different from a commercially available LysoTracker, the Stokes shift of DNS-C up to 240 nm (λ ex/em = 330/570 nm), is much larger than that of LysoTracker ~20 nm (λ ex/em = 573/595 nm). More importantly, the fluorescence of DNS-C keeps still high brightness after a time-lapsed imaging for 40 min in living cells, implying its remarkable photostability for long-term tracking. In addition, DNS-C can also clearly image the autolysosome, a critical subcellular compartment, forming by the fusion of lysosome with autophagosome in autophagy. These results suggest the promising utility of our probe as a powerful tool to real-time trace physiological processes of lysosomes. Image 1 • The azacyclo-localizing fluorescent probe DNS-C exhibits high specificity for lysosome and autolysosome labeling. • The large Stocks shift ~240 nm can efficiently avoid unwanted self-reabsorption and inner-filter effects. • The DNS-C can serve as a universal tracker for lysosome labeling in different kinds of cells. • The DNS-C exhibits excellent photostablility for long-term tracking the lysosome-related behaviors. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe 1 was synthesized for the detection of thiophenol on the basis of a unique thiophenol-mediated substitution-cyclization reaction. The probe 1 displayed 420-fold fluorescence intensity enhancement and highly selective and sensitive response for thiophenol over other competing sulfur species. This probe showed an excellent linear relationship in 10–140 μM and the low detection limit of 29 nM. The recognition mechanism of probe 1 toward PhSH was supported by the NMR spectrum and ESI-MS. Furthermore, the probe 1 was successfully applied for detection of thiophenol in living HepG2 cells. Image 1 • A novel fluorescent probe 1 for thiophenol was constructed on the basis of substitution-cyclization reaction. • Probe 1 features significant fluorescence enhancement up to 420-fold in response to thiophenol in aqueous solution. • This probe showed an excellent and wide linear relationship in 10–140 μM and with a low detection limit of 29 nM. • The probe could detect thiophenol in living cells. [ABSTRACT FROM AUTHOR]

Polydopamine fluorescent organic nanomaterials present unique physicochemical and biological properties, which have great potential application in bio-imaging and chemical sensors. Here, folic acid (FA) adjustive polydopamine (PDA) fluorescent organic nanoparticles (FA-PDA FONs) were prepared by a facile one-pot self-polymerization strategy using dopamine (DA) and FA as precursors under mild conditions. The as-prepared FA-PDA FONs had an average size of 1.9 ± 0.3 nm in diameter with great aqueous dispersibility, and the FA-PDA FONs solution exhibit intense blue fluorescence under 365 nm UV lamp, and the quantum yield is ~8.27%. The FA-PDA FONs could be stable in a relatively wide pH range and high ionic strength salt solution, and the fluorescence intensities are constant. More importantly, here we developed a method for rapidly selective and sensitive detection of mercury ions (Hg2+) within 10 s using FA-PDA FONs based probe, the fluorescence intensities of FA-PDA FONs presented a great linear relationship to Hg2+ concentration, the linear range and limit of detection (LOD) were 0–18 µM and 0.18 µM, respectively. Furthermore, the feasibility of the developed Hg2+ sensor was verified by determination of Hg2+ in mineral water and tap water samples with satisfactory results. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel NIR fluorescent probe for detection of NO with large Stokes shift was developed. • Probe could target in Golgi and monitor NO fluctuation upon stimulation with Glu and LPS. • Probe could in vivo imaging NO concentration in brain of depression-like mice model via tail vein injection. Depression is a debilitating mental illness that poses a serious threat to human health. Nitric Oxide (NO), as an important gasotransmitter, is closely associated with the pathogenesis of depressive disorders. Effective monitoring of NO fluctuation is beneficial for the diagnosis of depression and therapy assessment of antidepressants. Currently, there is a lack of effective methods for rapidly and sensitively identifying NO and elucidating its relationship with depression diseases. Herein, we developed a NIR dye TJ730-based fluorescent probe TJ730-Golgi-NO incorporating benzenesulfonamide as a Golgi-targeted moiety and the thiosemicarbazide group for NO detection. The probe exhibited turn-on fluorescence ability and a large Stokes shift of 158 nm, which shows high sensitivity, selectivity, and rapid response (<1 min) for NO detection. TJ730-Golgi-NO could detect exogenous and endogenous NO in cells stimulated by Glu and LPS, and target Golgi apparatus. Moreover, we disclose a significant increase of NO in the depression model and a weak fluorescence evidenced in the fluoxetine-treated depression mice. This study provides a competent tool for studying the function of NO and helping improve the effective treatment of depression diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] • Based on dicyanoisophorone skeleton a near-infrared fluorescent probe was prepared and used to detect CO with high selectivity. • Two emission channels ratiometric fluorescence changes can be observed through adjusting the ICT effect of probe by CO. • The design of the probe enables it to be used for detecting CO in lysosomal subcellular organelles and further validated through cell co-localization imaging experiments. • The probe can be used to detect the endogenous and exogenous CO in Hela cells and could be used in living mice. • The probe is capable of detecting endogenous and exogenous CO through cell imaging experiments and has been successfully used in living mice. Carbon monoxide (CO) as an endogenous gas signaling molecule possesses important physiological functions and is of great significance in the treatment of various diseases. Real-time tracking of CO in living organisms has become a research hotspot in recent years. This article presents a lysosomal targeted near-infrared ratio fluorescence probe (TBM-CO) for selective detection of CO based on the dicyanoisophorone skeleton and morpholine fragment. The probe TBM-CO with weak ICT effect can be transformed to precursor TBM-NH 2 with strong ICT effect by the traditional Tsuji-Trost reaction procession in the presence of Pd2+ ions. The mechanism was proved by DFT calculation or the MS and HPLC results respectively. In the near-infrared region an obvious ratio fluorescence intensity change (F 686 / F 616) is observed in vitro spectral experiments. The concentration titration experiments indicate that there is a good liner relationship between the ratio fluorescence intensity and the concentration in the range of 0 to 50 μM (R2 = 0.996) and the detection limit is calculated as 0.38 μM. The cell fluorescence imaging and co-localization experiments further demonstrate that TBM-CO is able to detect the exogenous and endogenous CO in lysosomal subcellular organelle. Finally, it was used to detect the changes of CO concentration in living mice successfully. In short, a probe with three advantages of near-infrared emission, ratiometric fluorescence and organelle targeting was reported and used to detect CO successfully in cells and in living mice. [ABSTRACT FROM AUTHOR]

A highly selective copper ions fluorescent probe based on the coumarin-type Schiff base derivative 1 (probe) was produced by condensation reaction between coumarin carbohydrazide and 1H-indazole-3-carbaldehyde. The UV–vis spectroscopy showed that the maximum absorption peak of compound 1 appeared at 439 nm. In the presence of Cu 2 + ions, the maximum peak decreased remarkably compared with other physiological important metal ions and a new absorption peak at 500 nm appeared. The job's plot experiments showed that complexes of 1:2 binding mode were formed in CH 3 CN:HEPES (3:2, v/v) solution. Compound 1 exhibited a strong blue fluorescence. Upon addition of copper ions, the fluorescence gradually decreased and reached a plateau with the fluorescence quenching rate up to 98.73%. The detection limit for Cu 2 + ions was estimated to 0.384 ppm. Fluorescent microscopy experiments demonstrated that probe 1 had potential to be used to investigate biological processes involving Cu 2 + ions within living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel resorufin-based fluorescent probe for selective detection of NE was developed. • Probe displayed rapid response time (<10 min) and high selectivity towards NE. • Probe could detect endogenous NE and exocytosis process by fluorescent imaging in living cells and depression-like behavior mice. Norepinephrine (NE), as an important neurotransmitter, is closely associated with the pathogenesis of anxiety and depressive disorders. Effective monitoring of NE fluctuation aids in the diagnosis of depression and the therapeutic assessment of the antidepressant intervention. The construction of novel fluorescent probes with high specificity towards NE for imaging in depression models is still in demand urgently. In this work, a novel resorufin-based red-emitting fluorescent probe for real-time tracking NE was developed. NE can significantly increase the fluorescence of probe LNE by triggering deprotection of carbonothioate ligand via nucleophilic substitution. The probe LNE demonstrated significant NE selectivity and sensitivity over other analytes in vitro. In addition, probe LNE showed a fast response time (<10 min), and the change in fluorescence signal was positively linked with NE concentration, which could be utilized to track the dysregulation of NE in vivo. More importantly, this powerful probe was successfully employed for real-time visual and imaging of NE in living cells and depression-like behavior animals. [ABSTRACT FROM AUTHOR]

• A novel probe for endogenous GSH was produced based on the coumarin derivative. • The probe exhibited high selectivity for GSH with the detection limit of 0.12 μM. • The fluorescence "turn on" of the probe is depended on de-metallization process. • The probe could be used to detect GSH in the HepG2 cells by fluorescence image. Discrimination and quantification of intracellular biothiols, such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH) under physiological conditions is significant for academic research and disease diagnosis. A new fluorescent probe (complex 1 -Cu2+) for discriminate detection of GSH was prepared by copper ions coordinate with coumarin carbohydrazide Schiff base derivative 1. In suitable buffer solution (CH 3 CN: HEPES = 3:2, v/v) and under appropriate pH condition (pH = 7.2–7.4), the UV–vis spectroscopy experiments showed that compound 1 and copper ion exhibited a 1:1 ratio binding mode and moderate binding ability. Fluorescence quenching of compound 1 was observed when it complexed with Cu2+ ions. An obviously fluorescence restoration appeared after addition of GSH to the solution of probe, which also exhibited a highly selectivity relative to cysteine (Cys) and homocysteine (Hcy) in the amino acid competitive experiments. The minimum detection limit was calculated to 0.12 μM by fluorescent method, which was distinctly below the physiological concentration of GSH in live cells. Its biological application to detect the endogenous GSH was further proved by the HepG2 cell fluorescence image test. [ABSTRACT FROM AUTHOR]