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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]

Glutathione is the most abundant non-protein thiols compound in cells and plays important metabolic roles. Changes in the amount of glutathione or its metabolic dysregulation can lead to a series of diseases. The determination of glutathione levels is very helpful to the diagnosis and treatment of the related diseases. A coumarin schiff base (compound 1 ) was synthesized from coumarin hydrazide and 2,6-pyridine dicarboxaldehyde and the fluorogenic probe for thiols (compound 1-Cu 2+ ) was prepared by coordinating compound 1 with copper ions. Compound 1 showed strong fluorescence, while compound 1-Cu 2+ hardly had fluorescence due to the paramagnetism and/or photoinduced electron transfer of Cu 2+ . However, after the addition of thiols-containing compounds, the fluorescence of compound 1 was restored. The UV–vis absorption and fluorescence spectra indicated that the fluorogenic probe had good thiols selectivity and sensitivity, particularly for glutathione in CH 3 CN:HEPES (3:2, v/v) buffer. It was successfully applied to the fluorescence imaging detection of glutathione in human cervical squamous cancer cells (SiHa cells). [ABSTRACT FROM AUTHOR]

A new fluorescence probe L based on naphthalimide has been synthesized for selective and quantitative detection of Cu 2 + in CH 3 CN:H 2 O (4:1, v / v ) solution. L exhibited a strong green fluorescence. Upon addition of 2 equiv. of Cu 2 + , the fluorescence emission shows a steady and smooth decrease until a plateau is reached with a 30-fold quenching of fluorescence intensity. In the presence of Cu 2 + , the absorbance peak of L maximum at 466 nm decreased, and a new absorption band at 600 nm appeared. Under the identical conditions, other physiological and environmental important metal ions induced negligible spectroscopic changes. The 1:2 stoichiometry binding mode of L with Cu 2 + was supported by the Benesi–Hildebrand analysis and ESI-MS spectra studies. The detection limit for Cu 2 + was estimated to be 64 ppb . Fluorescence microscopy experiments showed that L has practical application in living cells. [ABSTRACT FROM AUTHOR]

Abstract: A system based on FRET mechanism, comprising a coumarin donor and a rhodamine acceptor, was developed for the selective and quantitative detection of metal ions. Fluorescent chemosensors RCs, linked by 1,2-diethylamine, exhibit significant fluorescence enhancement and excellent selectivity toward Cu2+. Fluorescent probes CRB and CR6G, linked by hydrazide, function as ratiometric receptors for Cu2+ chromogentically and fluorogentically in organic-aqueous media. Furthermore, the characteristic rhodamine-based fluorescence response of CRB (excitation at 550 nm) exhibits high selectivity for Hg(II). The construction of this kind of universal FRET system opens a broader prospect for future design of ratiometric fluorescent probes. [ABSTRACT FROM AUTHOR]

A water-soluble fingerprint probe, GK-Ac, was designed and synthesized by using an unsymmetric structure of fluorescent groups. In the present contribution, incorporating a "rotor" structure to impede the rotation of rotational site groups, which can effectively enhance aggregation-induced emission and provide additional sites for modification. The results indicate that the fingerprint probe GK-Ac had faint fluorescence characteristics in aqueous solution, and the level 2 structure of latent fingerprints can be clearly observed at 450 nm fluorescence when soaked in lipid or sprayed with the GK-Ac aqueous solution. Moreover, the probe was also successfully applied to detect the level 3 structure of latent fingerprints with flat surfaces. The results can provide reliable theoretical guidance for the development of fingerprint fluorescence developer. [Display omitted] • An AIE-based water-soluble probe was designed and synthesized by using an unsymmetric structure. • The level 3 features of LFPs can be revealed by soaking or spraying with the GK-Ac. • GK-Ac only binds to lipids on LFPs and does not bind to other substances. [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]

Abstract: A simple FRET-based approach to ratiometric fluorescence sensing of Cr3+ in aqueous solution using glutathione and glucose as building blocks was achieved, inspired to the binding motifs of Cr3+ in glucose tolerance factors (GTF). Selectivity and competition experiments showed that this system featured high sensitivity (detection limit ≤0.1ppm) and excellent selectivity over other metal ions in buffer solution. Confocal fluorescence microscopy experiments had established the utility of the approach in monitoring Cr3+ within living cells. [ABSTRACT FROM AUTHOR]

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 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]

A specific Cu2+ sensor, 2-amino-3-(BODIPYmethyleneamino)maleonitrile (BDM), was established by a simple dehydration between BODIPY and diaminomaleonitrile. Cu2+ could be recognized by BDM over other competing metal ions in acetonitrile with distinct fluorescence emission signal response. Upon the addition of Cu2+ to BDM in acetonitrile, the maximum absorption at approximately 530 nm on the longer wavelength side was quenched, and the emission at 530 nm was ignited simultaneously. The fluorescence intensity enhancement could reach a maximum of 204 times the intensity of the BDM blank solution. The fluorescence "off-on" effect is established according to the Cu2+-induced fast intramolecular oxidative cyclization reaction, which could be deduced from the formation of an imidazole ring appended to the cyclization product (2-BODIPY-1 H -imidazole-4,5-dicarbonitrile, BMC). Single-crystal structure analysis of the sensor BDM and cyclization product BMC further demonstrated this oxidative cyclization. Finally, the Cu2+ recognition property of BDM was validated in SiHa cells and living zebrafish. Additionally, the blood-brain barrier of the zebrafish can be penetrated by the BDM dye and the neuron cells in the brain were stained. Unlabelled Image • Intramolecular oxidative cyclization reaction based sensor was established. • Single crystal structure analysis was also demonstrated. • Sensing property was validated in Siha cells and living vertebrate model, zebrafish. [ABSTRACT FROM AUTHOR]

A novel spiropyran-based colorimetric probe SP-DNP bearing a 2,4-dinitrophenyl group as a PhSH-responsive site was synthesized for the detection of thiophenol based on the ring open/closed isomerization process. Upon the addition of PhSH, the probe SP-DNP displayed a remarkable change in UV–vis spectra with a good linear relationship to concentration of PhSH, and result in apparent color change from purple to colorless that could be easily observed by the naked eye even in the presence of other interfering anions. Probe SP-DNP exhibited specific colorimetric response toward PhSH with very fast response (within 30 s) and high sensitivity (detection limit is 0.55 μM). In addition, the probe showed good selectivity and sensitivity toward PhSH through fluorescence quenching process. The sensing mechanism of the nucleophilic substitution-cyclization process was confirmed by 1H NMR and mass spectroscopic analysis. Moreover, probe SP-DNP could detect PhSH in real water samples. Image 1 • Probe SP-DNP was constructed on basis of thiophenol-induced transform merocyanine to spiropyran isomerization process. • The probe could colorimetric and fluorescent respond toward thiophenol with fast response and high sensitivity. • The probe has been successfully demonstrated in monitoring thiophenol in real water samples. [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]