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Ferric ion (Fe3+) serves as an essential and indispensable inorganic element in various biological process. Excess Fe3+ is harmful for biological systems and human health. Herein, highly sensitive carbon quantum dots (Fe-CQDs) for ferric ions were synthesized by a high-efficiency, one-step hydrothermal route utilizing L-arginine and citric acid. The prepared Fe-CQDs exhibited good water solubility, high photostability, and bright blue florescence with relatively high quantum yields (QYs) over 21.33% and a Stokes shift exceeding 100 nm. The functionalized Fe-CQDs offer rapid, sensitive, and selective recognition of Fe3+ with a linear relationship from 0.6 to 80 μM and a low detection limit of 0.2 μM. Moreover, the synthesized Fe-CQDs illustrated strong anti-interference properties in samples and buffer solutions. The developed sensor demonstrated high biocompatibility and was successfully applied for intracellular Fe3+ determination in SHSY5Y and HT22 cells, illustrating excellent imaging application. The present work provides a promising platform for the early clinical diagnosis of Fe3+-associated diseases. [ABSTRACT FROM AUTHOR]

The deployment of small‐molecule fluorescent agents plays an ever‐growing role in medicine and drug development. Herein, we complement the portfolio of powerful fluorophores, reporting the serendipitous discovery and development of a novel class with an imidazo[1,2‐a]pyridinium triflate core, which we term PyrAtes. These fluorophores are synthesized in a single step from readily available materials (>60 examples) and display Stokes shifts as large as 240 nm, while also reaching NIR−I emissions at λmax as long as 720 nm. Computational studies allow the development of a platform for the prediction of λmax and λEm. Furthermore, we demonstrate the compatibility of these novel fluorophores with live cell imaging in HEK293 cells, suggesting PyrAtes as potent intracellular markers. [ABSTRACT FROM AUTHOR]

Aryl alcohol‐type or phenolic fluorophores offer diverse opportunities for developing bioimaging agents and fluorescence probes. Due to the inherently acidic hydroxyl functionality, phenolic fluorophores provide pH‐dependent emission signals. Therefore, except for developing pH probes, the pH‐dependent nature of phenolic fluorophores should be considered in bioimaging applications but has been neglected. Here we show that a simple structural remedy converts conventional phenolic fluorophores into pH‐resistant derivatives, which also offer "medium‐resistant" emission properties. The structural modification involves a single‐step introduction of a hydrogen‐bonding acceptor such as morpholine nearby the phenolic hydroxyl group, which also leads to emission bathochromic shift, increased Stokes shift, enhanced photo‐stability and stronger emission for several dyes. The strategy greatly expands the current fluorophores' repertoire for reliable bioimaging applications, as demonstrated here with ratiometric imaging of cells and tissues. [ABSTRACT FROM AUTHOR]

Aryl alcohol‐type or phenolic fluorophores offer diverse opportunities for developing bioimaging agents and fluorescence probes. Due to the inherently acidic hydroxyl functionality, phenolic fluorophores provide pH‐dependent emission signals. Therefore, except for developing pH probes, the pH‐dependent nature of phenolic fluorophores should be considered in bioimaging applications but has been neglected. Here we show that a simple structural remedy converts conventional phenolic fluorophores into pH‐resistant derivatives, which also offer "medium‐resistant" emission properties. The structural modification involves a single‐step introduction of a hydrogen‐bonding acceptor such as morpholine nearby the phenolic hydroxyl group, which also leads to emission bathochromic shift, increased Stokes shift, enhanced photo‐stability and stronger emission for several dyes. The strategy greatly expands the current fluorophores' repertoire for reliable bioimaging applications, as demonstrated here with ratiometric imaging of cells and tissues. [ABSTRACT FROM AUTHOR]

A series of dithienothiophene S,S-dioxide (DTTDO) dyes was designed, synthesized, and investigated for their suitability in fluorescent cell imaging. Synthetized (D-π-A-π-D)-type DTTDO derivatives have molecule lengths close to the thickness of the phospholipid membrane, and they contain on both ends two positively charged or neutral polar groups to increase their solubility in water and to ensure simultaneous interaction with polar groups of the inner and outer part of the cellular membrane. DTTDO derivatives exhibit absorbance and emission maxima in the 517–538 nm and 622–694 nm range, respectively, and a large Stokes shift up to 174 nm. Fluorescence microscopy experiments revealed that these compounds selectively intercalate into cell membranes. Moreover, a cytotoxicity assay conducted on a model human live cells indicates low toxicity of these compounds at the concentrations required for effective staining. With suitable optical properties, low cytotoxicity, and high selectivity against cellular structures, DTTDO derivatives are proven to be attractive dyes for fluorescence-based bioimaging. [ABSTRACT FROM AUTHOR]

In vivo selective fluorescence imaging of carboxylesterase 2 (CES2) remains a great challenge because existing fluorescence probes can potentially suffer from interference by other hydrolases. In addition, some fluorescent probes that have been separately reported for measuring CES2 activity in vitro are affected by autofluorescence and absorption of the biological matrix due to their limited emission wavelength or short Stokes shift. Herein, based on the substrate preference and catalytic performance of CES2, a novel and NIR fluorescent probe was developed, in which a hemi-cyanine dye ester derivative was used as the basic fluorescent group. In the presence of CES2, the probe was hydrolyzed to expose the fluorophore CZX-OH (λabs ∼ 675 nm, λem ∼ 850 nm), which led to a notable red-shift in the fluorescence (∼175 nm) spectrum. Confocal imaging of cells and live mice demonstrated that the fluorescent signal of this probe was related to the real activities of CES2 in cancer cells. All these results will powerfully promote the screening of CES2 regulators and the analysis of CES2-related physiological and pathological processes. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis, photophysical characterization and use for cell imaging of 14 fluorophores derived from a hybrid Naphthalimide/Cinnoline fused backbone called "CinNapht". Photophysical properties of these fluorophores including absorbance, excitation and emission spectra have been recorded in CHCl3, DMSO and PBS+5 %BSA. They exhibit red emission associated to a large Stokes shift and fluorescence quantum yields up to 52 %. Theoretical calculations have been undertaken in order to provide elements of rationalization for a major part of the results. Some of these analogues have been tuned to enable imaging of cell organelles such as mitochondria, lysosome or lipid droplets. This study comes to confirm that CinNapht dyes can be considered as relevant alternatives to existing tools for cell imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A convenient approach to construct excimer emissive luminogens was established. • A double-bond linker between π-moiety and side-moiety is essential for AIE. • The structure-luminescence relationship was elucidated. • The high-resolution image of living Hela cells was observed. The excimer emission based on discrete π-stacked dimers of polycyclic π-systems has generated significant interest in the structure-luminescence relationship of excimers owing to their ultra-large Stokes shift. Herein, a series of excimer emissive luminogens were obtained by conjugating different polycyclic aromatic aldehydes (anthraldehyde, pyrenealdehyde and perylenealdehyde) with triphenylmethylamine. In crystalline states, all the molecules were arranged in the form of π-stacked arene dimers which were spatially isolated from each other by the bulky triphenylmethyl groups, and thus emitted bright excimer emission. The anthracene and pyrene derivatives showed fluorescence enhancement responses to grinding and the enhanced fluorescence could recover to the original state upon heating. The aggregation-induced emission (AIE) properties of them were dependent on the shapes and sizes of the polycyclic aromatic groups. The pyrene derivative showed the most excellent excimer-based AIE behavior among them. All of them were more apt to exhibit the excimer emission when formed nanoparticles with pluronic F-127 than that without pluronic F-127. Furthermore, PETP was utilized for bioimaging of living Hela cells and the high-resolution image was observed. [ABSTRACT FROM AUTHOR]

Dual red‐emitting fluorescent and water‐soluble silver nanoclusters (AgNCs) were synthesized in aqueous solutions through the reduce reaction method using lipoic acid‐modified‐poly(vinyl alcohol) as a novel protective ligand and sodium borohydride as a reducing agent. The obtained AgNCs exhibited a large Stokes shift and high stability. The fluorescence lifetime of the obtained AgNCs was 1.4×104 ns and the corresponding quantum yield reached 7.1 %. The obtained AgNCs showed highly sensitive and selective detection of Cu2+, in which the evaluation of Cu2+ was allowed in the range of 0–28 μM with a limit of detection (LOD) as low as 0.71 μM. Moreover, the obtained AgNCs are explored to application for bioimaging through incubation with ID8 cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe EDPH specializes in the detection of H 2 S with high selectivity, high sensitivity and good detection limits. • The probe EDPH has been shown to have applications in intracellular fluorescence imaging. • Purine-based fluorescent probes for the detection of H 2 S are a new direction. Hydrogen sulfide (H 2 S) is a gas with a toxic odor that plays an irreplaceable role in physiological activities within the mammalian body. Therefore, it is important to do the distribution and quantitative detection of H 2 S in mammalian cells. In this paper, a fluorescence probe (EDPH) based on purine scaffold was designed and synthesized with high sensitivity and good selectivity. H 2 S induced ether bond breakage in EDPH , resulting in a significant redshift of the absorption band (from 370 nm to 500 nm) with a Stokes shift of 130 nm. After the addition of H 2 S, the fluorescence intensity of EDPH showed a good linear correlation with the concentration of H 2 S, which enabled the quantitative detection of H 2 S with a low limit of detection (41 nM). Finally, the EDPH was applied to the cellular Hele, and the probe has good cellularity imaging capability for the detection of H 2 S in living systems. [ABSTRACT FROM AUTHOR]

The filamentous protein 'actin' plays an essential role in maintaining a proper cellular health and any disruption in its structure and dynamics may induce the growth and metastasis of cancerous cells. Recent studies have shown that, actin can serve as a potential therapeutic target and an indicator to examine the efficacy of modern chemotherapeutic agents. In this regard, the microscopy imaging of actin using fluorescent dyes can pave the way toward development of efficient drugs for cancer treatment. Herein, we report the synthesis of an organic fluorescent dye (BCH) which shows good selectivity toward F-actin at physiological pH. The dye displays a large Stokes shift (∼232 nm), strong emission intensity, good photostability and great sustainability over a wide pH range of 2–10. The dye can directly bind and localize in the actin-rich region of gut, testes and eye of a model organism, Drosophila melanogaster in both living and fixed cells and enable their confocal microscopy imaging without using any actin binding domain. Interestingly, the BCH dye is proved to be nontoxic in the tested organism and has been successfully employed as a potential tool to visualize cellular actin in living tissues of larva and pupa of the organism. [Display omitted] • A benzil biscoumarinyl hydrazone based fluorescent dye has been synthesized. • The dye can bind and image cellular filamentous actin directly without any binding domain. • The dye is proved to be nontoxic in model organism Drosophila melanogaster. • The dye has been successfully employed to visualize cellular actin in living tissues of larva and pupa of the organism. [ABSTRACT FROM AUTHOR]

[Display omitted] • An "off–on" long-wavelength fluorescent probe is synthesized for Cys detection. • The probe has a large Stokes shift (211 nm) and reacted with Cys specifically. • The probe can monitor Cys fluctuations caused by redox imbalance in HepG2 cells. • The probe can be used for fluorescence imaging in cells and mice. In this research, an "off–on" long-wavelength fluorescent probe (DCMN-Cl) based on (E)-2-(3-(2-(6-hydroxynaphthalen-2-yl)vinyl)-5,5-dimethylcyclohex-2-en-1-ylidene) malononitrile (DCMN) is designed and synthesized for cysteine (Cys) detection. DCMN-Cl exhibits a large Stokes shift (211 nm) and shows rapid response and high specificity to Cys. The fluorescence initensity at 635 nm reveals a good linear relationship with Cys concentration in the 0 to 50 μM range, and the detection limit is as low as 159 nM. The probe is also used for fluorescence imaging of Cys in cells and mice. Moreover, the probe provided visual evidence of Cu2+ and curcumin-induced intracellular Cys fluctuations. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel probe BD-C based on the FRET-ICT mechanism was designed to detect cysteine. • Probe BD-C had superior selectivity without the interference of other biological thiols. • Probe BD-C had large Stokes shift and the energy transfer efficiency reached 98.8%. • Probe BD-C had superior endoplasmic reticulum-targeting. Cysteine is an important thiol amino acid that is abundantly present in cells and has an important function in various life processes of the human body. Therefore, it is of great significance to develop an accurate method for monitoring cysteine concentration in cells. We designed and synthesized a novel FRET-ICT-based ratiometric fluorescence and colorimetric probe (BD-C) for detecting cysteine. As cysteine was gradually added, the fluorescence intensity of probe BD-C in buffer solution decreased at 614 nm and increased at 428 nm. The logarithm of the fluorescence intensity ratio to cysteine exhibited favorable linearity in the concentration range of 0.5–14.0 μM, with a detection limit of 395 nM. The energy transfer efficiency of this FRET system is up to 98.8%. BD-C demonstrated preeminent selectivity for cysteine and could specifically react with cysteine, though other sulfhydryl amino acids, such as GSH and Hcy, were present. Furthermore, BD-C exhibited outstanding targeting ability to the endoplasmic reticulum (ER) and was successfully applied in cellular imaging. [ABSTRACT FROM AUTHOR]

By connecting 1,8-naphthalimide and indole sulfonate, a ratio fluorescent probe capable of differential detection of hydrogen sulfite and hypochlorite was synthesized for the first time. It was able to achieve the qualitative detection of HSO3− and ClO− with high sensitivity and selectivity, respectively. It provides a multi-purpose probe and is based on different emission channels without mutual interference. The probe has the advantages of larger Stokes shift (ClO−: 115 nm, HSO3−: 88 nm), longer λem (ClO−: 515 nm, HSO3−: 548 nm) and better water solubility (DMF/PBS = 1:99, v/v). In addition, the probe is a ratio fluorescence probe, which can detect fluorescence intensity with two different emission waves. It provides internal self-calibration, reduces interference from the background and increases detection accuracy. In vitro cytotoxicity and imaging experiments show that the probe can effectively perform the detection of exogenous HSO3− and ClO− in cells. It can also achieve the detection of HSO3− and ClO− in the plasma environment. Because the probe can detect endogenous ClO−, it also has a good prospect for biological application in identifying tumor cells. [ABSTRACT FROM AUTHOR]

A deep-red emission and lipid droplets-targeted fluorescence probe (named ZFPy) for effective bioimaging of bisulfite was developed from flavone moiety and benzoindole derivative based on intramolecular charge transfer (ICT) and Förster resonance energy transfer (FRET) platform. ZFPy displayed promising fluorescence parameters including bright deep red fluorescence (615 nm), large Stokes shift (205 nm), extended emission window gap (140 nm), high absolute fluorescence quantum yield (4.1%) and stable emission signal output. In addition, ZFPy realized ratiometric fluorescence monitoring for SO 2 derivatives with low detection limit (30 nM), preferable linearity, high sensitivity and selectivity. Interestingly, dual fluorophores (i.e. the donor moiety and 1,1,2,3-tetra-substituent-1H-benzo[e]indol-3-ium iodide moiety) released the same emission band about 475 nm to enhance the emission signal when ZFPy reacted with SO 2 derivatives, to the best of our knowledge, this is the first synergetic FRET/ICT platform for fluorescence probe, which might effectively offer ZFPy a high sensitivity and low detection limit in the detection of SO 2 derivatives. More importantly, ZFPy could image exogenous and endogenous SO 2 derivatives in living HeLa, HepG2 and L-O2 cells with good biocompatibility and photostability. ZFPy also preferred to load on lipid droplets with high Pearson's coefficient (0.95). Image 1 • A ratiometric fluorescent probe (ZFPy) for rapidly monitoring SO 2 derivatives was developed. • FRET-based ZFPy displayed larger gap (140 nm) between two emission spectra. • This is a first synergetic FRET/ICT platform for fluorescence probe. • ZFPy was applied to image exogenous and endogenous SO 2 derivatives in living Hela, HepG2 and L-O2 cells. • ZFPy showed lipid droplets-targeted ability (Pearson's coefficient 0.95). [ABSTRACT FROM AUTHOR]

Photostable and near‐infrared (NIR)‐emitting organic fluorophores with large Stokes shifts are in great demand for long‐term bioimaging at deeper depths with minimal autofluorescence and self‐quenching. Herein, a new class of benzorhodamines and their analogues that are photostable and emit in the NIR region (up to 785 nm) with large Stokes shifts (>120 nm) is reported. The synthesis involves condensation of 7‐alkylamino‐2‐naphthols with 2‐[4‐(dimethylamino)‐2‐hydroxybenzoyl]benzoic acid, which leads to bent‐shaped benzorhodamines that emit orange fluorescence (≈600 nm); however, introduction of steric hindrance near the condensation site switched the regioselectivity, to provide a linear benzorhodamine system for the first time. The linear benzorhodamine derivatives provide bright fluorescence images in cells and in tissue. A carboxy‐benzorhodamine was applied for photothermal therapy of cancer cells and xenograft cancer mice. [ABSTRACT FROM AUTHOR]

Biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play key roles in biological processes, and detecting such thiols selectively is critical for understanding functions of biothiols. In this work, a pyridazine annelated perylene–based fluorescent probe PAPC is synthesized for highly selective detection of Cys. PAPC exhibits strong blue emission in PBS, while the red emission at 605 nm can be observed in the presence of Cys. The probe PAPC shows ratiometric fluorescence (I605/I460) detection of Cys with wide linear range of 1–120 μM and low detection limit of 0.19 μM. Super large Stokes shift (170 nm) and ratiometric fluorescence endow the probe low background signal. The discrimination of Cys over Hcy and GSH can be achieved through the difference of the ratiometric fluorescence. In addition, the probe has been proven to track Cys in real samples such as urine and HeLa cells. Therefore, PAPC probe is a promising candidate for detecting Cys in practical application. [ABSTRACT FROM AUTHOR]

A multiple turn-on fluorophore (FHCS), combining fluorescein, hydrazone, cyanuric chloride and salicylaldehyde chromone into a molecule, was identified and developed based on density functional theoretical calculation. It was expected that FHCS could express exclusive fluorescent signals and improved Stokes shifts when chelating Al3+ or Zn2+. After it was synthesized and characterized in detail, it was noted that FHCS could turn-on fluorescently discriminate trace Al3+ and Zn2+ under the optimized conditions, i.e., from no-fluorescence to strong blue fluorescence for Al3+ and to green fluorescence for Zn2+ with low detection limits of 5.37 × 10−8 M and 7.90 × 10−8 M respectively. Owing to its low toxicity, FHCS was successfully applied for quantitative determination of Al3+ and Zn2+ in natural aqueous samples and toxicity evaluation of Al3+ and Zn2+ in living cells and bio-tissues with excellent linear relationships. The action mechanisms for FHCS with Al3+ and Zn2+ were confirmed to form stable 5-member-co-6-member condensed rings between Al3+/Zn2+ and N/O atoms in FHCS by both theoretic and experimental methods, which resulted in turn-on fluorescence with different dipolar moments and improved Stokes shifts. A multiple turn-on fluorophore, combining fluorescein, hydrazone, cyanuric chloride and salicylaldehyde chromone into a molecule (FHCS), was identified and developed for turn-on fluorescently discriminate trace Al3+ and Zn2+ in natural aqueous, living cells and bio-tissue samples with quite low detection limits of 5.37 × 10−8 M and 7.90 × 10−8 M respectively. The action mechanisms for FHCS with Al3+ and Zn2+ were confirmed by both theoretic and experimental methods to form stable 5-member-co-6-member condensed rings between Al3+/Zn2+ and N/O atoms, which resulted in turn-on fluorescence with different dipolar moments and improved Stokes shift. Image 1 • A multiple turn-on fluorophore combining fluorescein, hydrazone, cyanuric chloride and salicylaldehyde chromone was developed. • It could turn-on fluorescently monitor Al3+ and Zn2+ in aqueous. • It was applied for cell imaging of Al3+ and Zn2+ in bio-samples. • The reaction mechanism was to form stable 5-member-co-6-member condensed rings with improved Stokes shift. [ABSTRACT FROM AUTHOR]

A rational design of a benzoperylene probe BP-3 with positive charge allows for turn-on excimer emission, and wash-free cell membrane imaging. BP-3 possesses excellent chemical, thermal and photo stability. And the Stokes shift of the excimer emission is considerably large (90–100 nm), which very much avoids the background fluorescence interference. [ABSTRACT FROM AUTHOR]

The spectroscopic properties for a number of new hydroxylated 2-stilbazoles were studied by absorption and fluorescence spectroscopy. The maximum absorption and emission wavelengths, the molar extinction coefficients, and the Stokes shift values of derivatives were given. The dependence of the spectral characteristics on pH was shown. The possibility of creating molecular logic systems and fluorescent dyes for bioimaging based on these derivatives was demonstrated. The dependence of fluorescence on the medium redox properties was established for an one of derivatives. The possibility of a fluorescent probe creating on its basis to assess the oxidative state of living systems was demonstrated. The probe has good biocompatibility and can be successfully used for fluorescence imaging in cells. [ABSTRACT FROM AUTHOR]

In this paper, a new strategy was presented for fluorescence labeling and imaging Al3+ in live cells with excess aluminum ions using thiolated fluorescence gold nanoclusters (Au NCs). The glutathione (GSH)-capped Au NCs were prepared via a green, facile one-pot method in aqueous solution and displayed excellent stability, ultrasmall size, monodispersity, and larger Stokes shift, which exhibits a relatively weak fluorescence at 650 nm Al3+-induced fluorescence enhancement of the GSH-Au NCs can be observed due to Al3+-triggered aggregation-induced emission (AIE) effect, which allows the role of GSH-Au NCs as a fluorescence light-up probe for detection of Al3+. Moreover, it was demonstrated that the fluorescence probe for Al3+ showed a wide detection range from 100 to 600 μM and good selectivity against other metal ions and common biomolecule. Furthermore, due to the advantages of excellent biocompatibility, low toxicity, red emission and high specificity, the proposed GSH-Au NCs fluorescence probes are suitable for the imaging of high concentrations of aluminum ions in cells, which can be applied to the diagnosis of cellular aluminum poisoning. Schematic illustration of the synthesis process of GSH-Au NCs and the fluorescence enhancement of GSH-Au NCs after adding Al ion due to the Al3+ triggered aggregation of the GSH-Au NCs. Image 1 • First report of the Al3+ rapid fluorescence detection in live cells with excess aluminum ions using thiolated Au NCs. • Al3+ as linkers can induce photoluminescence boost of thiolated Au NCs nearly 40-fold through AIE. • The biosensor is suitable for imaging of excess aluminum ions in cells due to their hypotoxicity, red emission of 650 nm. [ABSTRACT FROM AUTHOR]

New L‐shaped fluorophores possessing five conjugated rings have been synthesized through a four‐step procedure involving diketopyrrolopyrrole synthesis and its double N‐alkylation, followed by trimethylsilyl bromide‐mediated rearrangement to thieno[2,3‐f]isoindole‐5,8‐dione and an intramolecular Friedel–Crafts reaction. In comparison with the parent isoindolediones and π‐expanded diketopyrrolopyrroles, these new dyes show red‐shifted absorption and emission (up to ≈630 nm). Their structural rigidity is responsible for both the observed small Stokes shifts and large fluorescence quantum yields. Tissue imaging studies revealed that these new dyes show advantageous features including minimal autofluorescence interference and pronounced solvent‐sensitive emission. Interestingly, there is a fundamental difference between a dye possessing an amino group and its analog bearing an N‐alkyl substituent. The former dye under two‐photon excitation at 900 nm gives bright images whereas its N‐alkylated counterpart does not. A new type of membrane localization has been discovered by an N‐alkylated isoindoledione possessing a benzofuryl substituent. In spite of the fact that the fluorescence quantum yield of this dye in a range of solvents is rather low, it does stain cell membranes exclusively. This new mode of cellular staining opens the door towards further development of membrane staining dyes. [ABSTRACT FROM AUTHOR]

The deficiency and excess of Fe3+ will lead to biological disorders and even many diseases. So, measuring the levels of Fe3+ in human body has drawn great attentions for health monitoring. Fluorescence method has been broadly applied because of high sensitivity, real-time detection and intracellular imaging. In this work, a new lipidic conjugated polymer, poly[3-{2-[2,5-Bis-(2-ethyl-hexyloxy)-4-propenyl-phenyl]-vinyl}-9-butyl-6-methyl-9H-carbazole] (PBMC), has been synthesized and used to prepare the conjugated polymer nanoparticles (CPNs-PBMC) by coprecipitation with poly (styrene- co -maleic anhydride) (PSMA). The CPNs-PBMC exhibited large Stokes shift (141 nm), small average diameter (43.96 nm), low toxicity and excellent photostability. Meanwhile, the CPNs-PBMC was highly sensitive to Fe3+ and has a lower detection limit of 0.63 nmol/L. The sensing mechanism was based on aggregation-induced fluorescence quenching of CPNs-PBMC in the presence of Fe3+ because of chelation and electrostatic interaction. Furthermore, the critical micelle concentration was measured by fluorescence method. More interestingly, the fluorescence of CPNs-PBMC could be circularly quenched and recovered using Fe3+ and EDTA, which may supply a possible control by logic gate. Furthermore, the fluorescence imaging showed that CPNs-PBMC could detect Fe3+ in living cells. A new lipidic conjugated polymer (PBMC) has been synthesized and used to prepare the conjugated polymer nanoparticles (CPNs-PBMC) by coprecipitation with PSMA. The CPNs-PBMC exhibited large Stokes shift (141 nm), small average diameter (43.96 nm), low toxicity and excellent photostability, and could detect Fe3+ with high sensitivity (LOD = 0.63 nmol/L) based on aggregation-induced fluorescence quenching (AIFQ). Moreover, the fluorescence of CPNs-PBMC could be controlled by logic gate using Fe3+ and EDTA. Finally, CPNs-PBMC was successfully applied to Fe3+ detection in living cells by confocal imaging. Image 1 • The CPNs-PBMC exhibited large Stokes shift (141 nm). • The CPNs-PBMC was highly sensitive to Fe3+ and has a lower detection limit of 0.63 nmol/L. • The CPNs-PBMC detected successfully Fe3+ in living cell. • The fluorescence of CPNs-PBMC could be controlled by logic gate using Fe3+ and EDTA. [ABSTRACT FROM AUTHOR]

A novel ratiometric fluorescence probe for hypochlorous acid was constructed by coumarin and pyridinium fluorophore based on the Forster resonance energy transfer (FRET) and intramolecular charge transfer (ICT) platform. In this ICT/FRET system, the energy transfer efficiency is high to 94.3%. Moreover, the probe could respond to hypochlorous acid with high selectivity and sensitivity, and exhibited a large Stokes shift. It was interesting to find that the probe could recognize hypochlorous acid via a new mechanism, in which the α-position of carbonyl group was oxidized to form a diketone derivative. More importantly, the probe was successfully applied to the ratiometric imaging of both exogenous and endogenous hypochlorous acid in living RAW 264.7 cells, with low toxicity and high photo-stability. Image 1 • A ratiometric fluorescent probe ZPAC for rapidly monitoring hypochlorous acid. • A new mechanism, α position of carbonyl group was oxidized to form a diketone derivative. • FRET-based ZPAC displayed larger gap between two emission spectrum. • ZPAC was applied to image exogenous and endogenous hypochlorous acid in living RAW264.7 cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A red-emissive fluorescent probe HBTI for reversible recognition of HSO 3 − and H 2 O 2 has been developed. • HBTI showed fluorescence on–off-on variations upon sequential addition of HSO 3 − and H 2 O 2. • HBTI is applicable to detect HSO 3 − in real food samples. • HBTI is mitochondria-targetable and can be used in cell imaging. Reducing agent SO 2 and oxidant H 2 O 2 are two essential substances in cells, and the balance between them is closely related to the survival of cells. SO 2 derivative HSO 3 − is often used as food additive. Therefore, simultaneous detection of SO 2 and H 2 O 2 is of great significance in biology and food safety. In this work, we successfully developed a mitochondria-targeted red fluorescent probe (HBTI), which has excellent selectivity, high sensitivity and large Stokes shift (202 nm). HBTI and HSO 3 −/SO 3 2− undergo Michael addition on the unsaturated C=C bond, and the addition product (HBTI-HSO 3 −) can react with H 2 O 2 to restore the conjugated structure. Fluorescence changes from red to non-emissive and then restores to red, and can be detected quickly and visually. In addition, HBTI has been successfully targeted mitochondria, and achieved dynamic reversible response to SO 2 /H 2 O 2 in living cells, and has been successfully applied to detect SO 2 in food samples. [ABSTRACT FROM AUTHOR]

• A novel NIR colorimetric-fluorescence probe was prepared for detection of hydrogen sulfide. • The probe showed rapid, specific and sensitive detection of hydrogen sulfide with a large Stokes shift. • The probe was capable of imaging hydrogen sulfide in living cells and mice. We presented here a novel near-infrared fluorescent probe based on 2-(2′-hydroxyphenyl)benzothiazole -dicyanoisophorone as fluorophore and 2,4-dinitrobenzenesulfonyl moiety as detection functionalized group for the discrimination of hydrogen sulfide (H 2 S). Probe L exhibited good specificity and sensitivity "turn on" response at 720 nm with a large Stokes shift (155 nm), rapid response (< 60 s) and low detection limit (3.15 × 10−7 M), which also could be identified by the naked eyes. Moreover, probe L was successfully used to image exogenous/endogenous H 2 S in cells and mice, which demonstrated its potential applications in living systems. A novel fluorescein based on 2-(benzo[ d ]thiazol-2-yl)phenol-dicyanoisophorone probe was constructed for the discrimination of hydrogen sulfide. The probe was applied for the rapid, sensitive, large Stokes shift, colorimetric and large near-infrared fluorometric determination of H 2 S, based on the displacement approach. The low cytotoxicity and excellent imaging performance was successfully applied for mitochondrial localization in living cells and endogenous and exogenous H 2 S detection in vivo. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A new lysosome-targeted fluorescent probe FAP1 for the recognition of FA was developed. • Probe FAP1 showed high sensitivity and selectivity for detecting FA with a large Stokes shift (130 nm). • Probe FAP1 exhibited good biocompatibility and could be used to image FA in lysosome. Formaldehyde (FA) is one of reactive carbonyl species (RCS), which is involved in various physiological and pathological processes of organisms. Herein, a novel fluorescent probe (FAP1) containing lysosomal localization group for the detection of FA was designed and synthesized. The probe exhibited good fluorescence recognition performances for FA, such as large Stokes shift (130 nm), specific selectivity, good anti-interference ability, and low minimum detection limit (16 nM). It is worth mentioning that the probe has good biocompatibility and could be applied to the imaging detection of FA in lysosome. [ABSTRACT FROM AUTHOR]

Abstract Cysteine (Cys) plays a vital role in many physiological processes, and also is closely related to various diseases, thus the development of novel high selectivity and sensitivity fluorescent probes for in situ monitoring of biothiol (Cys) is crucial. Herein, we present a fluorogenic method to detect Cys in vitro and live cells based on fluorescent protein chromophores, which have been modulated by chemical reaction. Probe (RFP) is a fluorescence turn on probe with red emission wavelength and large Stokes shift (127 nm). This Michael-addition reaction-based probe exhibits low detection limit (18.7 μM), fast response time, and low cytotoxicity. RFP can differentiate the Cys and Hcy, using the difference of reaction time between probe and Cys or Hcy. Together, this probe exhibited excellent cell permeability, and can be successfully applied to detect the endogenous Cys in living cells. Highlights • Provide a fluorogenic method to detect Cys based on fluorescent protein chromophores. • Realize the red emission and large Stokes shift using chemical modulation method. • Differentiate the Cys and Hcy using the difference of reaction time. • Detection endogenous or exogenous Cys in living cells and served as bioimaging reagent. [ABSTRACT FROM AUTHOR]

Highlights • The method with photocaged probes for imaging was efficient and spatiotemporal. • The two probes NDPPI and NNDPPI could be applied in cells and human tissues with satisfactory results. • This strategy can be used in other modified reagents for controlling biological function with light. Abstract Two compounds with nitrobenzene-derived caging groups were designed and synthesized for cells and tissues imaging. After 350 nm irradiation, the two reagents can realize highly efficient fluorescence turn on with large Stokes shift. As for the two probes can bare out a common functional group of aldehyde group under UV irradiation, it may be used for detection of cysteine, DNA methylation in a spatiotemporal method with selectivity. The idea of design and synthesis might be used in other modified reagents for controlling biological function with light. [ABSTRACT FROM AUTHOR]

Abstract In this work, we have designed and synthesized a dinitrobenzene-sulfonate tetrahydro[5]helicene (H-DNP) as an effective fluorescent probe for detection of hydrogen sulfide (H 2 S). Upon the addition of H 2 S, a significant fluorescence enhancement (75-fold) at 495 nm can be observed with a distinct color change from colorless to yellow. Additionally, H-DNP shows low background spectroscopic signal, large Stokes Shift up to ~140 nm, good sensitivity, rapid response time less than 2 min, low detection limit (48 nM) and high selectivity toward common bio-thiols (Cysteine, Homocysteine and Glutathione). Compared with the previous dinitrophenoxy tetrahydro[5]helicene, this probe has shorter response time and lower detection limit. Most importantly, this probe H-DNP has low toxicity to cells and excellent cell permeability, which can be applied to visualize H 2 S in living cells. Graphical abstract Unlabelled Image Highlights • A tetrahydro[5]helicene based fluorescence probe displayed a rapid, sensitive and selective in response to H 2 S. • The probe has very low detection limit and fast response time. • The response mechanism is confirmed to be thiolysis reaction induced by H 2 S. • The detection of intracellular H 2 S was successfully demonstrated in living cells. [ABSTRACT FROM AUTHOR]

A new scaffold for producing efficient organic fluorescent materials was identified: 2,5‐diamino‐4,6‐diarylpyrimidine featuring a C4N4 elemental composition. Single‐step installation of two aryl groups at the 4,6‐positions of the pyrimidine core delivered fluorescent organic materials in a modular fashion. A range of fluorescent compounds with distinct absorption/emission properties was readily accessed by changing the aromatic attachments. A generally high absorption coefficient and quantum yield were observed, including C4N4 derivatives that could fluoresce even in the solid state. The two amino groups at the 2,5‐positions of the pyrimidine were essential for intense fluorescence with a large Stokes shift, which was corroborated by structural relaxation to a p‐iminoquinone‐like structure in the excited state. Besides live‐cell imaging capabilities, fluorescent labeling of a protein involved in autophagy elucidated a new protein–protein interaction, supporting potential utility in bioimaging applications. A new scaffold for producing efficient organic fluorescent materials was identified: 2,5‐diamino‐4,6‐pyrimidine featuring a C4N4 elemental composition (see figure). Single‐step installation of two aryl groups at the 4,6‐positions of the pyrimidine core delivered fluorescent organic materials in a modular fashion. [ABSTRACT FROM AUTHOR]

• A series of iridium(III) solvato complexes with good water solubility are designed and synthesized. • They can be used for multicolor cytoplasm imaging of living cells. • Two-photon excited imaging and fluorescence lifetime imaging microscopy have been achieved. Fluorescence microscopy imaging provides an indispensable way to visualize morphological details in tissue with subcellular resolution. Of the various imaging agents currently available, heavy-metal complex based probes offer a powerful tool for live cell imaging, primarily due to their excellent photophysical properties, including evident Stokes shifts, high photoluminescence efficiency and relatively long emission lifetime of phosphorescent signals. Herein, we have designed and synthesized seven water soluble cationic iridium(III) solvato complexes (1 − 7) for live cell imaging. The emission colors of these iridium(III) complexes can be tuned from green to red in PBS buffer (phosphate buffered saline). In particular, multicolor phosphorescent imaging for cytoplasm staining of living cells has been realized. More importantly, two-photon excited imaging and fluorescence lifetime imaging microscopy have also successfully been applied for complex 7. [Display omitted] A series of iridium(III) solvato complexes (1 − 7) with good water solubility have been designed and synthesized for multicolor cytoplasm imaging of living cells. Furthermore, two-photon excited imaging and fluorescence lifetime imaging microscopy have also been achieved. [ABSTRACT FROM AUTHOR]

The abnormal expression of cytochrome P450 2J2 (CYP2J2) is closely related to the proliferation of human cancer cells. In this study, a red-emitting probe with an aggregation-induced emission (AIE) effect for the quantification of CYP2J2 was developed by modifying the typical AIE fluorescent group tetraphenylethylene (TPE) through two-step synthesis. Upon addition of CYP2J2, the probe underwent O-demethylation and spontaneously 1,6-elimination reactions of p-hydroxybenzyl that allowed it to alter its photophysical properties, thus realizing light-up detection of CYP2J2 with extremely large Stokes shift (236 nm), excellent sensitivity and selectivity, low detection limit (1.09 nM). Moreover, this new AIE-active probe with good biocompatibility was admirably employed to tracking endogenous CYP2J2 in living cells. • An AIE-based fluorescent probe (TPE-Bn) was designed to detect CYP2J2. • This probe showed significant Stokes shift (236 nm), good photostability, excellent sensitivity and selectivity, and low cytotoxicity. • This probe can be used to visualize endogenous CYP2J2 in living cells and tissues. [ABSTRACT FROM AUTHOR]

The fluorescent imaging of formaldehyde ( FA ) in live cells and plant tissues plays important role in physiological and pathological studies. However, the development of effective tools or facile strategies to selectively detect FA in bio-systems still remains a great challenge. Herein, two simple probes ( BT-1 and BT-2 ) based on N -heterocyclic derivates have been designed and synthesized for detection of FA in live cells and plant tissues with a significant fluorescence enhancement and large Stokes shifts (about 116 nm). These probes can fast react with FA (less than 3 min), showing the potential ability of detection FA in real time. After interaction with FA , BT-1 has a longer absorption and emission wavelength, better response characteristics as compared with BT-2 . In vitro tests, the maximal fluorescence intensity of each spectrum exhibited excellent linear correlation with the concentration of FA added. Furthermore, the test strips coated with BT-1 can not only differentiate different concentrations of FA and but also recognize FA gas from other relative gases through the changes of fluorescence color which can easily observed by naked eye as these test strips were excited by hand-held UV lamp. More importantly, BT-1 has been successfully used to detect exogenous and endogenous FA in live Arabidopsis thaliana tissues, demonstrating its potential application for studies of physiological and pathological processes associated with FA . [ABSTRACT FROM AUTHOR]

An imidazo[1,5-α]pyridine-based fluorescence probe NIPY-DNP with a large Stokes shift (193 nm) has been successfully developed for highly selective, sensitive and rapid detection of H 2 S. The selective deprotection of 2,4-dinitrophenyl ether group of NIPY-DNP by H 2 S led to a dramatic fluorescent enhancement (273-fold) at 505 nm within 5 min in PBS buffer solution. The sensing mechanism is proposed on the basis of the thiolysis reaction by H 2 S, which has been confirmed by HPLC and HRMS. The detection limit is 0.36 μM, which is superior to the other reported H 2 S probes. Additionally, cell imaging studies demonstrated that NIPY-DNP could be used to visualize H 2 S in living cells. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO 2), as a known important sulfur oxide in RSS, has an essential role in achieving the homeostasis of organisms. The development of a highly sensitive and selective fluorescent probe for monitoring SO 2 is of great interest in understanding its pathophysiology. Herein, we developed a new near-infrared FRET-based fluorescent probe QD , in which quinolinium fluorophore was selected as the donor and the dicyanoisophorone fluorophore was selected as the acceptor. Probe QD had dual colorimetric and ratiometric fluorescence, larger Stokes shift (277 nm) and longer emission wavelength (677 nm). The fluorescence spectrum showed that QD was highly selective and sensitive with excellent linear response concentration range of 2.5–80 μM. Importantly, probe QD allowed detection of SO 2 derivatives and bioimaging of lysosome-targeted in live cells. [Display omitted] • Showing a strong NIR fluorescence. • Large Stokes shift of 277 nm and wide detection rang of 2.5–80 μM. • Showing high sensitivity and selectivity. • Achieving the dual colorimetric and ratiometric fluorescent strategy. • Achieving the detection of exogenous and endogenous SO 2 derivatives in living cells. [ABSTRACT FROM AUTHOR]

The novel V-shaped donor-π-acceptor-π-donor compounds bearing an aldehyde group (1Pip , 2EtO , and 3TEG) were designed, synthesized, and evaluated as the two-photon excited fluorescence probes for the selective detection of cysteine (Cys). Their structures were fully characterized by 1H NMR, 13C NMR, FT-IR, and HRMS. The optical properties of the target compounds in various solvents were studied in details and the time-dependent density functional theory calculations were performed to shed light on their electronic structures. It is found that all of them exhibit large Stokes shifts (6331-10047 cm−1). 1Pip and 3TEG are capable of detecting Cys with high selectivity, good anti-interference ability, and favorable two-photon absorption performance. The limits of detection were determined to be equal to 0.15 μM for 1Pip and 0.73 μM for 3TEG. The possible recognition mechanism was also validated by 1H NMR and HRMS. One- and two-photon fluorescence imaging experiments indicate that 3TEG shows more satisfactory cellular membrane permeability than 1Pip , and it can successfully visualize the endogenous and exogenous Cys in living cells. These results imply that 3TEG has potential as a two-photon fluorescence probe for detecting Cys in biological samples. [Display omitted] • Three novel D-π-A-π-D type two-photon absorption compounds were developed to detect Cys. • 3TEG shows high selectivity to Cys, favorable two-photon absorption property, large Stokes shifts, and good biocompatibility. • 3TEG has been successfully utilized to image endogenous and exogenous Cys in living cells. [ABSTRACT FROM AUTHOR]

We presented the design, synthesis and preliminary evaluation of the 2,4-dinitrobenzenesulfonate (DNBS) of imidazo[1,5- α ]pyridine derivative, NIPY-DNBS , as a turn-on fluorescent probe for the detection of thiols in aqueous solution. The reaction mechanism was confirmed by means of fluorescence, absorption and HRMS. The large Stokes shift (201 nm), high sensitivity (the detection limit for Cys was calculated to be as low as 0.17 μM) and fast response (10 min) of NIPY-DNBS make it a practical and reliable method for fluorescence imaging. Furthermore, application of NIPY-DNBS for the selective detection of intracellular thiols has been successfully demonstrated in living A549 cells. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is an important gas signal molecule, which participates in a variety of pathological and physiological processes. In this paper, a novel near-infrared fluorescence probe (NIR-H 2 S) with azido as the reaction site was designed and synthesized. NIR-H 2 S utilizes the reducibility of H 2 S to detect H 2 S, which effectively avoids the interference of biological thiols. NIR-H 2 S is a D-π-A dye, and thiophene is the π-bridge, which can not only enhance the π conjugation of the molecules but also increase the vibrational flexibility of the molecules. Therefore, NIR-H 2 S shows a significant near-infrared (NIR) turn-on signal at 693 nm, with a large Stokes shift (258 nm). Cell imaging experiments show that NIR-H 2 S has high contrast imaging ability and can be used to detect H 2 S in cells. The excellent performance of NIR-H 2 S indicates that NIR-H 2 S is one of the valuable candidate probes for the detection of H 2 S in living cells. • A fluorescence probe NIR-H 2 S was designed based on D-π-A. • NIR-H 2 S exhibits fluorescence turn-on response at 693 nm toward H 2 S. • NIR-H 2 S has a large Stokes shift (258 nm), which greatly improves sensitivity and signal-to-noise ratio in imaging. • Using azide as response site, NIR-H 2 S has excellent selectivity to H 2 S. [ABSTRACT FROM AUTHOR]

[Display omitted] • A near-infrared fluorescent probe based on malononitrile isophorone. • For detection of Hg2+ in the environment and live-cell fluorescence imaging. • Using thioacetal as the detection group, the sulfur in this group can specifically combine with Hg2+. • The fluorescent probe has good selectivity and good detection speed. Hg2+ in the environment endangers human health, and a convenient monitoring method is needed for the detection of Hg2+. In this study, we constructed a dual colorimetric near-infrared fluorescent probe (E)-2-(3-(3-(1,3-dithian-2-yl)-4-hydroxystyryl)-5,5-dimethylcyclohex-2-en-1-ylidene)malononitrile (YF-Hg), based on the malononitrile isophorone. YF-Hg can detect Hg2+ rapidly and sensitively, with fluorescence emission in the near-infrared region (659 nm) with an obvious color change from violet to red in the visible light range. In addition, the low toxicity and large Stokes shift (191 nm) of YF-Hg also suggest that it is a potential tool for live-cell fluorescence imaging. [ABSTRACT FROM AUTHOR]

• A novel quinoline-fluoran hybrid fluorescent dye QF has been easily prepared. • A copper ion-selective fluorescent probe QFH has been developed based on QF. • QFH shows good performance in tracing intracellular copper ions by fluorescence imaging. Developing fluoran dyes as fluorescent probes is interesting because it is of great significance to extend their applications from the printing industry to other fields such as fluorescence analysis and medicine. We here present a new quinoline-fluoran hybrid dye QF , which delivers fluorescent signals in water (pH: 4.0 - 9.0) with the maximum absorption and emission centered at 514 nm and 597 nm, respectively. In addition, a large Stokes shift (83 nm) can be observed when compared to that of rhodamine B. QF is further employed for the preparation of a new fluorescent probe QFH , which exhibits high selectivity towards copper ions with the limit of detection down to 1.54 nM via a Cu2+-triggered spirolactam ring opening and hydrolysis process. Significantly, QFH can be applied for the detection of copper ions at physiological pH conditions (pH: 6.0 - 9.0) and shows low cell cytotoxicity, which allows it to be a candidate for tracing Cu2+ by cell imaging. A novel quinoline-fluoran hybrid fluorescent probe for copper ion-selective detection and application in cell imaging. [Display omitted] [ABSTRACT FROM AUTHOR]

7-Aminocoumarins are commonly used as fluorophores for application in molecular monitoring, cell imaging and many other fields. Herein, a series of fluorescent 7-aminocoumarins were prepared via Er(OTf) 3 -catalyzed Pechmann condensation of 3-aminophenols with β-ketoesters in 19–96% yields. Among them, 7-(dimethylamino)-4-(pyridin-4-yl)-2H-chromen-2-one (3j) displayed a fluorescence maximum with a wavelength of 557 nm and a large Stokes shift of 166 nm in DMSO, and showed strong fluorescence in sub acid to alkaline environment. Besides, 3j exhibited excellent photo stability and stable fluorescence intensity in the presence of some metal cations and biomolecules in neutral solution. A series of fluorescent 7-aminocoumarins were prepared via Er(OTf) 3 -catalyzed Pechmann condensation of 3-aminophenols with β-ketoesters. Among them, 7-(dimethylamino)-4-(pyridin-4-yl)-2H-chromen-2-one (3j) exhibited excellent photophysical properties, and displayed strong fluorescence in sub acid to alkaline environment. [Display omitted] • An efficient approach to access fluorescent 7-aminocoumarins •Easy work-up and broad substrate scopes •Excellent fluorescence properties [ABSTRACT FROM AUTHOR]

Organic fluorescent materials have been widely used in various fields including visualization of latent fingerprints and imaging of lysosomes. High-performance organic fluorescent molecules based on simple molecular structures are still limited and highly demanded for high-definition and high-contrast imaging of latent fingerprints and lysosomes. In this work, two organic fluorescent molecules (DANPAN and DANBEN) were developed based on dimethylamino naphthalenyl phenylethene structure. These two molecules have quite different fluorescent properties, and the position of cyano group significantly affects the optical properties of these dimethylamino naphthalenyl phenylethene derivatives. Compound DANPAN shows strong yellow emission in solid state, while compound DANBEN has strong fluorescent emission in organic solutions. In addition to these differences, both compounds have large Stokes shifts and positive solvatochromic properties. Further studies showed that these compounds could be used to display latent fingerprints on various substrate surfaces. The obtained fingerprint images have excellent contrast and high resolution. It is also found that these molecules could specifically stain lysosomes in living cell within short incubation time. This work provides a series of new high-performance organic fluorescent materials with diverse applications. Highly emissive dimethylamino naphthalenyl phenylethene derivatives have been synthesized, which show large Stokes shifts and positive solvatochromic properties. These compounds could be applied for visualization of latent fingerprints and specific localization of lysosomes in living cell imaging. [Display omitted] • Two dimethylamino naphthalenyl phenylethene derivatives are synthesized. • These molecules show large Stokes shifts and positive solvatochromic properties. • These compounds could be applied for visualization of latent fingerprints on various substrate surfaces. • These molecules could be used for specific localization of lysosomes in living cell imaging. [ABSTRACT FROM AUTHOR]

• Excluding interference and detecting microcystin-LR based unique fluorescence method. • The performance of MC-BDKZ was tested by calculating recovery rate in water samples. • MC-BDKZ showed excellent fluorescence imaging to intracellular MC-LR and lysosome. • The response mechanism of MC-BDKZ to MC-LR was deeply discussed. Cyanobacteria blooms that cause the death of aquatic and terrestrial organisms have attracted considerable attention since the 19th century. The most typical toxin in cyanobacteria blooms is cyanobacteria toxin, particularly microcystin-LR (MC-LR). Therefore, a simple and highly efficient method for detecting MC-LR plays a role in studying the ecological toxicology of MC-LR. However, as MC-LR itself is located in a complex environment, traditional techniques present complex and false-positive defects. To address the above issues, novel technologies should be explored and discovered. Herein, we describe the development of MC-BDKZ as the first paradigm of probes that can concurrently report MC-LR in natural lakes and cells. This novel material shows large Stokes Shift and possesses good photostability and high sensitivity. Considering the properties mentioned above, MC-BDKZ not only achieves the detection of MC-LR in the lake water samples, but also completes the imaging of exogenous MC-LR in cells. Moreover, the interference of many factors in the lake and cells is excluded completely in the process of MC-LR detection. We comprehensively analyzed the response principle and potential application of MC-BDKZ in the process of MC-LR detection. Compared with the conventional MC-LR detection technologies, fluorescence probe technology shows better convenience and greatly reduces distance from the practical application in vitro and in vivo. We envisioned that the development of this visual research tool could provide crucial clues for exploring the pathogenesis of MC-LR in body. [Display omitted] [ABSTRACT FROM AUTHOR]

A red-emitting (above 600 nm) fluorescent probe based on 3-hydroxyflavone has been developed for the detection of hydrogen sulfide with high sensitivity, good selectivity and a large Stokes shift (162 nm). When the probe was treated with hydrogen sulfide, a remarkable fluorescence enhancement (112-fold) was obtained. Application of this probe was successfully demonstrated by imaging intracellular hydrogen sulfide in living RAW264.7 cells. [ABSTRACT FROM AUTHOR]

In current work, one novel benzothiazole-based fluorescent chemosensor (TZ-BO) with ESIPT luminescence mechanism was designed for the detection of hydrogen peroxide (H 2 O 2) as typical reactive oxygen species (ROS). The boronate catenary in our designed probe molecule TZ-BO is both the blocking group of ESIPT and the reactive group of H 2 O 2. The synthesized probe TZ-BO has the advantages of large Stokes shift, high sensitivity, good selectivity, and fast reaction speed to H 2 O 2. The ability of the probe to detect H 2 O 2 in aqueous media and exogenous H 2 O 2 in cells by fluorescence signal was investigated. The experimental results manifested that probe TZ-BO is able to sensitively detect H 2 O 2 using a fluorescence method in an excellent linear range of H 2 O 2 concentration from 0 to 60 μM (R2 = 0.994). The detection limit was determined as 1.0 × 10−6 M. Most importantly, the probe TZ-BO with highly low cytotoxicity can effectively detect exogenous H 2 O 2 in HeLa cells. This probe provides a promising tool for monitoring the real concentration level of H 2 O 2 in related physiological and pathological researches. [Display omitted] • Novel ESIPT-based benzothiazole derivative (TZ-BO) as a fluorescent chemosensor was synthesized for H 2 O 2 detection. • TZ-BO was stable in physiological pH and exhibited excellent H 2 O 2 -response in neutral and slightly alkaline environments. • Low cytotoxic TZ-BO exhibited good responsion and selectivity to exogenous H 2 O 2 in HeLa cells. [ABSTRACT FROM AUTHOR]

Oxidative stress plays significant roles in the development of various diseases. H 2 O 2 acts as a signaling molecule physiologically or harmful substance pathologically and the mitochondria are one of the most active places for the generation of H 2 O 2. Thus, a new mitochondria-targeted probe 1 for H 2 O 2 detection was synthesized herein, based on D-π-A structure with a large Stokes shift (150 nm) due to its ICT process. To improve its water solubility and sensitivity, probe 2 with PEG chain and probe 3 with two responsive boronated groups were then designed based on the structure of probe 1. As a result, the fluorescence intensity of probe 2 was far higher than that of probe 1 and probe 3 not only in vitro experiment but in cell imaging study with a larger linear range and signal-to-noise ratio, rendering it the best probe for further exogenous and endogenous H 2 O 2 detection in Hela cells. [Display omitted] • Based on the principle of donor-π-acceptor and p -pinacolborylbenzyl group as recognition part, three novel probes for H 2 O 2 were designed. • These near-infrared probes with a large Stokes shift (150 nm) had good selectivity and sensitivity toward H 2 O 2. • The fluorescence intensity of the PEGylated probe was far higher than those of other probes not only in vitro experiment but in cell imaging study. • The probes had good mitochondria-targeting capacities. [ABSTRACT FROM AUTHOR]

In this paper, we report a new strategy for constructing a dye library with large Stokes shifts. By coupling a dark donor with BODIPY acceptors of tunable high quantum yield, a novel dark resonance energy transfer (DRET)- based library, named BNM, has been synthesized. Upon excitation of the dark donor (BDN) at 490 nm, the absorbed energy is transferred to the acceptor (BDM) with high efficiency, which was tunable in a broad range from 557 nm to 716 nm, with a high quantum yield of up to 0.8. It is noteworthy to mention that the majority of the non-radiative energy loss of the donor was converted into the acceptor's fluorescence output with a minimum leak of donor emission. Fluorescence imaging tested in live cells showed that the BNM compounds are cell-permeable and can also be employed for live-cell imaging. This is a new library which can be excited through a dark donor allowing for strong fluorescence emission in a wide range of wavelengths. Thus, the BNM library is well suited for high-throughput screening or multiplex experiments in biological applications by using a single laser excitation source. [ABSTRACT FROM AUTHOR]

Through harvesting of the increased Stokes shift of CdS QDs via Cu-doping, the concentration-quenching or aggregation-quenching of CdS QDs was largely alleviated. A dually-enriched strategy with both polyvinylpyrrolidone (PVP) twisting and SiO2 loading was developed for generating a highly luminescent doped-dots (d-dots) assembly for improved cell imaging. [ABSTRACT FROM AUTHOR]