Fast-response Fluorescent Probe Research Articles

Shedding light on ONOO- detection: the emergence of a fast-response fluorescent probe for biological systems.

ONOO-, a bioactive molecule, plays a critical role in inflammation-related signaling pathways and pathological mechanisms. Numerous studies have established a direct correlation between elevated ONOO- levels and tumor progression. Therefore, investigating ONOO- levels in inflammation and tumors is of utmost importance. Fluorescence imaging presents a highly sensitive, non-invasive, easily operable, selective, and efficient method for ONOO- detection in situ. In this study, we designed and synthesized a rhodamine-based probe, NRho, which effectively identifies tumors, inflammatory cells, tissues, and organs by detecting ONOO- content. The synthesis process of NRho is simple, yielding a probe with favorable spectral characteristics and rapid response. Our cell imaging analysis has provided novel insights, revealing distinct ONOO- levels among different types of cancer cells, with hepatocellular carcinoma cells exhibiting higher ONOO- content than the others. This observation marks the proposal of such variations in ONOO- levels across cancer cell types. Furthermore, our study has showcased the practicality of our probe in live organ imaging, enabling the identification of tumors from living organs within a brief 5-minute incubation period. Additionally, our findings highlight the rapid detection capability of the probe NRho in various tissue samples, effectively identifying inflammation. This research holds important promise in advancing biomedical research and clinical diagnosis.

A New and Fast-Response Fluorescent Probe for Monitoring Hypochlorous Acid Derived from Myeloperoxidase.

Hypochlorous acid (HOCl) has been implicated in numerous pathologies associated with an inflammatory component, but its selective and sensitive detection in biological settings remains a challenge. In this report, imaging of HOCl was realized with a thiomorpholine-based probe as derivative of nitrobenzothiadiazole (NBD-S-TM). The fluorescence is based on photoinduced electron transfer by using nitrobenzothiadiazole core as a donor and thiomorpholine substituent as an acceptor. NBD-S-TM showed high sensitivity and a fast response to HOCl k = (2.6 ± 0.2) × 107 M-1s-1 with a 1:1 stoichiometry. The detection limit for HOCl was determined to be 60 nM. Furthermore, the desirable features of NBD-S-TM for the detection of HOCl in aqueous solutions, such as its reliability at physiological pH, rapid fluorescence response, and biocompatibility, enabled its application in the detection of HOCl in myeloperoxidase enzymatic system. Moreover, NBD-S-TM exhibited excellent selectivity and sensitivity for HOCl over other biologically relevant species, such as hydrogen peroxide and peroxynitrite. The fluorescent S-oxidized product (NBD-S-TSO) is only formed in the presence of HOCl. Probing with NBD-S-TM may be helpful to further the development of high throughput screening assays to monitor the activity of myeloperoxidase.

Fast Response Fluorescent Probe with a Large Stokes Shift for Thiophenol Detection in Water Samples and Cell Imaging

Fast Response Fluorescent Probe with a Large Stokes Shift for Thiophenol Detection in Water Samples and Cell Imaging

Selective, stoichiometric and fast-response fluorescent probe based on 7-nitrobenz-2-oxa-1,3-diazole fluorophore for hypochlorous acid detection

A new selective probe containing the thiomorpholine unit (TM) was synthesized and examined for the fluorescence-based detection of hypochlorous acid (HOCl). Connection of TM with the fluorophore, 7-nitrobenz-2-oxa-1,3-diazole (NBD) effectively suppresses NBD fluorescence, whereas a HOCl-induced oxidation of TM to its S-oxide turns on a green emission. HPLC analysis shows that the reaction is stoichiometric and no sulfone is formed. Moreover, neither hydrogen peroxide nor peroxynitrite are able to oxidize the probe. Experimental data indicates that NBD-TM probe can be used to detect HOCl generated by myeloperoxidase (MPO). Presented results may be helpful in developing a novel class of fluorescent and luminogenic probes for the imaging of HOCl.

Multi-dimensional imaging of endogenous leucine aminopeptidase via fast response fluorescent read-out probe

Abnormal expression of leucine aminopeptidase (LAP) in living system is associated with various diseases. But so far, there is no detailed imaging analysis of LAP distribution in living cells and organisms with fluorescent probes. In this work, we present a fast-response fluorescent read-out probe (NBD-S-Leu) for imaging LAP in living cancer cells and zebrafish models from multi-dimensional. NBD-S-Leu was constructed by incorporating a dipeptide (cysteinyl-leucine: Cys-Leu) into a commercially available fluorescent 4-chloro-7-nitro-2,1,3- benzoxadiazole (NBD-Cl) scaffold with rational design. Upon exposure to LAP, the amide bond in dipeptides will be cleaved, and subsequently, an intramolecular S→N rearrangement will be occurred, resulting in a dramatic fluorescence light-up and realize the chemoselective detection of LAP. The sensing mechanism was fully supported by TD-DFT calculations and HPLC-HRMS analysis. NBD-S-Leu performs well and features excellent water solubility, fast-response (~4 min) to LAP, low cytotoxicity, as well as good tissue-permeable. Furthermore, NBD-S-Leu has been effectively utilized to image endogenous LAP activity in various types of living cells and zebrafish models. Impressively, with the help of 2.5-dimensional (2.5 D) and 3-dimensional (3 D) confocal imaging, the endogenous LAP distribution in different living cells and zebrafish organs were clearly observed from more than one angle for the first time owing to the high signal-to-noise ratio. Collectively, this fluorescent read-out system does not only provide an alternative method for accurate detection of LAP activity but also can help LAP-related pathological analysis in living organisms and screening inhibitors.

Fast-response fluorescent probe with favorable water solubility for highly sensitive imaging of endogenous tyrosinase in living cells and zebrafish model

Tyrosinase (TYR) is an important polyphenolic oxidase enzyme and usually regards as a biomarker of melanoma cancer. Highly effective tracking TYR activity in vivo will help to study the mechanism of TYR in living organisms and forecasts related diseases. In this study, we present a novel TYR-activatable fluorescent probe (CHMC-DOPA) for tracking TYR activity in vitro and in vivo. CHMC-DOPA is constructed by incorporating dopamine (DOPA) moiety into a fluorescent chloro-hydroxyl-merocyanine (CHMC) scaffold. Upon exposure to TYR, the dopamine unit in CHMC-DOPA is oxidized to a dopaquinone derivative, and an intramolecular photo-induced electron transfer (PET) process between CHMC fluorophore and o-dopaquinone will take place, the fluorescence of CHMC-DOPA is quenched rapidly. Therefore, the evaluation of TYR activity is established in terms of the relationship between fluorescence quenching efficiency and TYR activity. In our experiments, CHMC-DOPA shows various advantages, such as fast response (8⬰min), low concentration of TYR activation (0.5 U/mL), good water-solubility, as well as the lowest detection limit (0.003 U/mL) compared with previously reported works. Furthermore, CHMC-DOPA also exhibits excellent cell membrane permeability and low cytotoxicity, which is successfully used to monitor endogenous TYR activity in living cancer cells and zebrafish models. CHMC-DOPA performs well, and we anticipate that this newly designed novel platform will provide an alternative for high effective monitoring TYR activity in biosystems.

A new fast response colorimetric and fluorescent probe for the detection of bisulfite and its application on test strips

ABSTRACT A new carbazole-based colorimetric and fluorescent probe CBB for the detection of bisulfite (HSO3 −) has been developed via nucleophilic addition reaction. Probe CBB can detect HSO3 − with excellent sensing properties including high selectivity and sensitivity, fast response (5 s). More importantly, probe CBB system not only can be applied to monitor HSO3 − in environment with excellent solid properties based on test strips but also can be used for the detection of HSO3 − in real-water samples with satisfactory results.

A dual-channel and fast-response fluorescent probe for selective detection of HClO and its applications in live cells

In this work, a novel water-soluble fluorescent probe (BODIPY-P) was designed and synthesized for HClO detection. The probe exhibited ratiometric fluorescence variation with rapid response upon addition of NaClO in deionized water (PBS buffer, pH 7.4) and the change of fluorescence color from red to orange was distinguishable by the naked eyes. The ratio of fluorescence intensity (F567/F629) gradually increased and showed a good linear correlation with HClO concentration in the range of 0–5 eq. The detection limit was estimated to be 31.6 nM, which enables the quantitative detection of trace amount of HClO realizable. Fluorescence titration experiments demonstrated that the probe was highly selective and competitive over other ROS, biothiols, common anions, physiological relevant cations. The recognition mechanism of the probe towards HClO was proved to be HClO-promoted oxidative cleavage of olefinic CC double bond. Most importantly, the fluorescence imaging of BODIPY-P in L929 cells suggested that the probe was cell membrane permeable and low toxic, which was capable of monitoring exogenous and endogenous HClO within a few seconds.

Novel fluorescent probe for rapid and ratiometric detection of β-galactosidase and live cell imaging

β-Galactosidase (β-gal) is an important biomarker for primary ovarian cancers and cell senescence; however, a fast response fluorescent probe for ratiometric monitoring is still rare. A novel, ratiometric water-soluble fluorescent probe (FLM) for β-gal was developed. The emission ratio F550/F450 reached the maxima at about 5 min and can be used for real-time detection of β-gal; the ratio gained an ultimate enhancement of about 260-fold. The ratio (F550/F450) displayed brilliant β-gal-dependent performance and responded linearly with β-gal activity. The probe showed wonderful biocompatibility and was successfully used for the bioimaging of endogenous β-gal in the human ovarian cancer cell line OVCAR-3.

A simple and fast-response fluorescent probe for hypochlorite in living cells

A novel fluorophore pyrido[1,2-a]benzimidazole was synthesized and used as a fluorescent probe for hypochlorite based on the oxidation of hydrazine to carboxyl group. The detection limit was measured to be as low as 7.0 nM. The probe can realize fast-detection for hypochlorite within 60 s. Furthermore, it could be used for imaging in living cells.

A novel FRET-based fluorescent probe for the selective detection of hydrogen sulfide (H2S) and its application for bioimaging.

Hydrogen sulfide (H2S) is an endogenously produced gaseous signaling molecule with multiple functions in many physiological and pathological processes. Herein, our group developed a novel fluorescent probe (Flu-N3) for H2S on the basis of the 7-amino-4-methylcoumarin and fluorescein FRET system. Adding H2S to a solution of Flu-N3 resulted in a clearly observable fluorescence enhancement (50-fold). This probe showed high sensitivity and selectivity towards H2S over other reactive species with a detection limit of 0.031 μM and a fast response time (within 8 s). Moreover, Flu-N3 displayed little toxicity to HepG-2 cells and was successfully applied to image exogenous and endogenous H2S in living cells and nude mice.

A Michael addition–cyclization-based switch-on fluorescent chemodosimeter for cysteine and its application in live cell imaging

We designed and synthesized a fast response fluorescent probe, BTAC (benzothiazol-azacoumarin), for detection of cysteine (Cys).

A highly sensitive and selective fluorescent probe for fast sensing of endogenous HClO in living cells.

A new fluorescence probe was developed for HClO detection under physiological conditions, which displayed fast response (t1/2 < 30 s) and large off-on fluorescence increase (>1000-fold) toward HClO with high sensitivity and selectivity. The probe was successfully applied for the detection of both exogenous and endogenous HClO in living cells. Using the probe-based tool, we could observe the H2S-induced HClO biogenesis in living cells for the first time.

A highly selective and fast-response fluorescent probe based on Cd-MOF for the visual detection of Al3+ ion and quantitative detection of Fe3+ ion

A new luminescent Cd(II)-based metal-organic framework, [Cd(PAM)(4-bpdb)1.5]·DMF (Cd-MOF, PAM = 4,4′-methylenebis(3-hydroxy-2-naphthalene-carboxylic acid) and 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene) was successfully synthesized by solvothermal synthesis method. The Cd-MOF reveals excellent luminescence property which can selectively detect Al3+ and Fe3+ ions among other interfering metal ions. The detection limit is 0.56µM for Al3+ ion in aqueous solutions, and it is obvious lower than the maximum standard of Al3+ ion in drinking water of 7.41µM which is defined by the WHO. More importantly, the Cd-MOF shows an obvious luminescent color change from yellow to blue under the UV lamp irradiation at 365nm with the dropping of Al3+ ion, which can make it apply to the visual detection. And, the detection based on the test paper was explored for the first time. In addition, the Cd-MOF can also be used for quantitative detecting Fe3+ ion, and the LOD for Fe3+ ion can be as low as 0.3µM which is lower than most reported MOFs. It is worth noting that Fe3+ and Al3+ ions can not interfere with each other. These properties make it become an excellent luminescence sensor for the detection of Al3+ and Fe3+ ions.

A highly selective, pH-tolerable and fast-response fluorescent probe for Fe3+ based on star-shape benzothiazole derivative

Abstract A star-shape benzothiazole-based molecule TBB , obtained through a simple condensation reaction of 2-aminothiophenol with 1,3,5-benzenetricarboxylic acid in the presence of available catalyst polyphosphoric acid (PPA), has been exploited as a highly selective fluorescent Fe 3+ probe over other metal ions in aqueous media (H 2 O/THF, v/v = 4/6). For this fast-response probe with a response time of 50 s, its quenching mechanism involving in the combination of static and dynamic quenching is confirmed by the test of time-correlated single photon counting (TCSPC) experiments. Noticeably, the probe TBB is suitable for Fe 3+ detection in a wide pH range (3–12) of aqueous solution, and it can be successfully applied for Fe 3+ quantitative measurement in real water samples.

A highly specific BODIPY-based fluorescent probe for the detection of nerve-agent simulants

Nerve agents such as Sarin, Soman and Tabun are all very toxic organophosphorus (OP) compounds capable of being used as chemical weapons. Unfortunately, the ability to rapidly sense OPCs is still an ongoing challenging. In this report, we designed and synthesized a fast-response fluorescent probe (1) for the detection of OP nerve agent simulants with high selectivity and sensitivity. The probe contains an electron donor-to-acceptor system in which a BODIPY moiety acts as a reporter group and the hydroxyl group as a reaction site for nerve agent simulants. The electron deficient nitrile group was introduced to lower the background fluorescence of the probe. A significant enhancement of fluorescence intensities at 531nm was observed upon gradual addition of nerve agent simulants on excitation at 480nm. The emission intensity rapidly reached its maximum within only 540s on adding 6 equiv. of nerve agent simulants with a quantum yield of the reaction product of 0.808, 81-fold larger than the probe itself (Ф=0.01). A color change in following a paper test experiment verified its portable application.

O,o-Difluorination of aromatic azide yields a fast-response fluorescent probe for H2S detection and for improved bioorthogonal reactions.

The development of efficient bioorthogonal reactions for sensing of endogenous biomolecules and for bioconjugation should be of paramount importance in the field of chemical biology. In this work, the o,o'-difluorinated aromatic azide was firstly employed to develop a new fast-response fluorescent probe 1 for H2S detection and for bioorthogonal reactions. Compared with non- and mono-fluorinated probes, 1 showed faster reaction toward H2S, the third gasotransmitter, in buffer (pH 7.4), implying that the reaction rate could be enhanced by the dual-fluorine groups. Furthermore, such enhanced reaction rates of 1 were also observed in the Staudinger reaction and strain-promoted azide-alkyne cycloaddition (SPAAC) based on the comparison studies of the non-fluorinated probe. Our results firstly highlight that the o,o'-difluorinated aromatic azide group should be useful for fast bioorthogonal reactions and H2S detection.

A fast-response fluorescent probe for hypochlorous acid detection and its application in exogenous and endogenous HOCl imaging of living cells.

A facile fluorescent probe (NBD-DOP) has been developed to detect hypochlorous acid (HOCl) in this study. The probe consists of a NBD fluorophore and a dopamine moiety that reacts with HOCl specifically. The dopamine group quenches the fluorescence of NBD efficiently through a photoinduced electron transfer (PET) effect. Experimental data showed that NBD-DOP could detect HOCl with ultrafast response, high sensitivity and high selectivity in a wide pH range. The probe could also be used to detect the myeloperoxidase enzyme that produces HOCl. Moreover, NBD-DOP has been applied in the imaging of exogenous and endogenous HOCl in living cells by confocal fluorescence microscopy.

A fast response and high sensitivity thiol fluorescent probe in living cells

Up to date, the design of highly selective and fast response probes for Cys, Hcy, and GSH is still a challenge and very few examples have been reported so far. In this study, we synthesized a 1,8-naphthalimide-based probe bearing maleimide group to selectively detect thiol. After introduce thiol, the fluorescence intensity of probe showed significant enhancement, but other amino acids did not generate any change. The kinetic study showed that the reaction was complete within 120s for Cys, Hcy and GSH, indicating that probe reacts rapidly with thiol under the experimental conditions. Furthermore, the ability of probe to detect thiol in living cells via an enhancement of the fluorescence was proved.

A water soluble and fast response fluorescent turn-on copper complex probe for H2S detection in zebra fish

According to the displacement method, herein we reported a water soluble copper complex [Cu(MaT-cyclen)2] as a fluorescent probe for the detection of H2S. For this, 1-((1-((10-methylanthracen-9-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)-1,4,7,10-tetraazacyclododecane (MaT-cyclen) was synthesized first. To improve its solubility in aqueous media, sodium acetate group was introduced into 8-hydroxy-2-quinoline successfully. MaT-cyclen was chelated with Cu(II) to form [Cu(MaT-cyclen)2] complex, which displayed high sensitivity and selectivity for H2S over the other possible competitive substances on the basis of forming CuS. Meanwhile, [Cu(MaT-cyclen)2] displayed rapid response (<1min), well reversibility, lowest detection limit (205nM), and high sensitivity for recognizing H2S in aqueous solution. Furthermore, its potential utility for biological applications was confirmed by fluorescence imaging of H2S in live cells as well as in zebra fish.