Dual-functional Fluorescent Probe Research Articles

Design, synthesis and application of a dual-functional fluorescent probe for reactive oxygen species and viscosity.

A fluorescence probe based on cyanine fluorophore was designed and synthesized in this work, which can be used to determine viscosity and reactive oxygen species (e.g., OCl-, ONOO-) at different wavelengths. Under a low viscosity medium, the fluorescence quantum yield of the probe is very low; however, with the increase of the medium viscosity, the probe's emission at 571nm is enhanced by nearly 25-fold due to the inhibition of intramolecular rotations. On the other hand, the probe shows a rapid and linear fluorescence response at 710nm to OCl- or ONOO- within 1min. The different spectral response regions of the probe permit the selective detection of both viscosity and reactive oxygen species. Furthermore, the probe is demonstrated to be cell permeable and capable of detecting the viscosity and the total amount of OCl-/ONOO- in living cells with the help of confocal microscope fluorescence imaging.

A dual-functional fluorescent probe for sequential determination of Cu2+/S2- and its applications in biological systems.

A new acylhydrazine-derived Schiff base fluorescence probe DMI based on "ON-OFF-ON" fluorescence strategy was presented in this paper. Probe DMI could detect Cu2+ selectively and sensitively with dramatic fluorescence quenching in CH3OH-PBS (v/v=3:7) mixed solution. Once the complex DMI-Cu2+ interacted with S2-, 10.67-folds fluorescence increase was induced via a displacement mechanism under the same experimental conditions. The corresponding detection limits for Cu2+ and S2- were calculated to be 1.52×10-8M and 1.79×10-8M, respectively. The structures of DMI and DMI-Cu2+ were systematically characterized by Job's plot analysis, ESI-MS, IR, X-ray diffraction and density functional theory calculations. Furthermore, fluorescence imaging in MCF-7 cells and zebrafish demonstrated the probe DMI could act as a useful tool to monitor and track intracellular Cu2+ and S2-, which was encouraged by remarkable fluorescence performance and low cytotoxicity. Importantly, the complex DMI-Cu2+ could be applied to detect corrupt blood samples, which could estimate the time of death.

Simultaneous Discrimination of Hypochlorite and Single Oxygen during Sepsis by a Dual-Functional Fluorescent Probe.

Hypochlorite (ClO-) and singlet oxygen (1O2) commonly coexist in living systems and exert important interplaying roles in many diseases. To dissect their complex inter-relationship, it is urgently required to construct a fluorescent probe that can discriminate ClO- and 1O2 in living organisms. Herein, by taking the 3-(aliphaticthio)-propan-1-one group as the unique recognition unit for both ClO- and 1O2, we proposed the first fluorescent probe, Hy-2, to simultaneously discriminate ClO- and 1O2 with high sensitivity and selectivity. Probe Hy-2 itself showed fluorescence in blue channel. After treatment with ClO- and 1O2, respectively, pronounced fluorescence enhancements were observed in the green channel and red channel correspondingly. Moreover, upon development of the probe with aggregation-induced emission (AIE) characteristics, the probe could work well in a solution with high water volume fraction. Probe Hy-2 was also able to accumulate into mitochondria and was utilized as an effective tool to image exogenous and endogenous ClO- and 1O2 in mitochondria. Significantly, as the first trial, probe Hy-2 was employed to simultaneously monitor the variation of ClO- and 1O2 level in cecal tissues of rat in the cecal ligation and puncture (CLP)-induced polymicrobial sepsis model. The results demonstrated that the expressed ClO- and 1O2 levels were tightly correlated with the severity of sepsis, inferring that the overproduction of ClO- and 1O2 is an important factor in the pathogenesis of sepsis. The probe illustrated herein may provide a guide for further exploring the functions of ClO- and 1O2 in various diseases.

Development of dual function polyamine-functionalized carbon dots derived from one step green synthesis for quantitation of Cu2+ and S2- ions in complicated matrices with high selectivity.

The study of biologically important Cu2+ and S2- ions has drawn great attention in the recent years since an abnormal level of these ions is an indication for health impairment. Therefore, a reliable strategy for effective fluorescence determination of Cu2+ and S2- ions was developed. Simply, the method based on economical plant-dependent thermolysis procedure for efficient green synthesis of water dispersible luminescent polyamine-based carbon dots (PA@C-dots) utilizes Vitis vinifera juice as precursor with a high quantum yield (32.1%) and good photo-stability. The fluorescent PA@C-dots were characterized by different spectroscopical, physical, and structural techniques. Furthermore, the synthesized PA@C-dots can be used as an efficient dual functional fluorescent probe for the sensitive and selective estimation of Cu2+ and S2- ions. The incorporation of Cu2+ ions and their adsorption on the surface of PA@C-dot skeleton leads to the respectable fluorescence quenching of C-dots (turn-off mode). The Cu2+-PA@C-dot was found to be sensitive to S2- ions. The addition of S2- recovers the fluorescence (turn-on mode) of Cu2+-PA@C-dots, thanks to its capacity for withdrawing Cu2+ from the shell of PA@C-dots. Fluorescence quenching in the range of 0.07-60μM Cu2+ was obtained with LOD and LOQ of 0.02 and 0.066μM, respectively. Sulfide detection provides linearity in the range of 0.8 to 95μM with LOD and LOQ of 0.24 and 0.79μM, respectively. The optimal excitation and emission wavelengths for all experiments are 435nm and 498nm, respectively. Experiment results elucidate that the proposed method is suitable for Cu2+and S2- ion detection in environmental water samples. Graphical abstract Green synthesis of polyamine-functionalized nanoprobe by thermolysis method from plant source as bifunctional sensing platform for determination of Cu2+ and S2- in environmental water samples.

A novel fluorescent protein chromophore analogue to simultaneously probe lysosome viscosity and β-amyloid fibrils

Alzheimer's disease (AD) is an incurable neurodegenerative disease. Better diagnosis of AD is extremely important for therapeutic interventions. The amyloid cascade hypothesis and its revised version identify insoluble β-amyloid deposition as a good diagnostic biomarker for AD. We hypothesize that lysosomal viscosity may also act as an auxiliary biomarker for AD based on literature research. Herein, we have successfully developed a FP chromophore analogue C25 as a dual-functional fluorescent probe which can respond effectively to the Aβ fibrils and enhanced lysosomal viscosity with distinguishable turn-on fluorescence signals around 570 nm and 600 nm, respectively. The probe C25 can also monitor the Aβ degradation in the lysosomes. The probe C25 can serve as a promising tool for developing early diagnosis and innovative therapeutics of AD.

A lysosome-targeting dual-functional fluorescent probe for imaging intracellular viscosity and beta-amyloid.

A lysosome-targeting dual-functional fluorescent probe was rationally designed and developed for imaging intracellular lysosomal viscosity and beta-amyloid. More importantly, the real-time tracking of the dynamic movement of lysosomes, as vesicle structures, has been achieved using Lyso-MC.

A dual-responsive fluorescent probe for detection of fluoride ion and hydrazine based on test strips.

Hydrazine (N2H4) and fluoride ion (F-) are regarded as environmental pollutants and potential carcinogens. A dual-functional fluorescent probe (probe 1) was developed for both F- and N2H4 with high selectivity and sensitivity. 1 was based on nucleophilic aromatic substitution reaction for N2H4 detection and selective cleavage of 4-nitrobenzenesulphonyl group for the determination of F-. The limits of detection of probe for F- and N2H4 were 77.82 nM and 29.34 nM, respectively, which are far below the threshold limit value (TLV) of United States Environmental Protection Agency (EPA). The home-made test strips of 1 provided the positive tool for F- and gaseous N2H4 in different system. And the confocal fluorescence images indicated that 1 can quantitatively detect N2H4 in living PC12 cells. Promisingly, 1 has great prospects for N2H4 imaging and determining in living system.

A coumarin based fluorescent probe for rapidly distinguishing of hypochlorite and copper (II) ion in organisms.

A dual-functional fluorescent probe based on coumarin fluorophore for monitoring ClO- and Cu2+ was synthesized and characterized. The identification mechanisms for ClO- and Cu2+ induced different colorimetric and ratiometric changes. ClO- caused a colorimetric change from yellow to colorless and 120 nm blue-shifted emission spectra from red to blue. Besides, Cu2+ induced a remarkable fluorescence quenching behavior and 36 nm blue-shifted absorption spectra accompanied by the color change from yellow to luminous yellow. As expected, Probe 1 displayed excellent selectivity and sensitivity for detecting ClO- and Cu2+ over other competing ions in their respective systems. The limits of detection for ClO- and Cu2+ were 24.62 nM and 0.39 nM, respectively. The recognition mechanisms were proved by 1H NMR, mass spectrum and theoretical calculations. More importantly, the reversibility of Cu2+ could be applicable to rapid quantification for ClO-/Cu2+. Thus, the strategy for sensing ClO-/Cu2+ was carried out, which revealed broad applications of Probe 1 in multiple actual water and biology.

A dual functional fluorogenic probe for visualization of intracellular pH and formaldehyde with distinct fluorescence signals.

In this study, a single fluorescent probe (DPFP) containing a 1,8-naphthalimide dye and a homoallylamino group for imaging pH and formaldehyde (FA) has been developed that exhibits significant blue fluorescence (λem at 455 nm) under acidic pH conditions (pH < 7.0) and green fluorescence (λem at 555 nm) in the presence of FA, respectively. Furthermore, probe DPFP was successfully applied to image acidic lysosomes and exogenous or endogenous FA in living HeLa cells.

A turn-on fluorescent probe for sensitive detection of sulfide anions and ascorbic acid by using sulfanilic acid and glutathione functionalized graphene quantum dots

The rational surface functionalization of graphene quantum dots (GQDs) has attracted much attention to extend their application in fabricating bio/chemical sensing platform. In this paper, a GQDs-based copper ions (Cu2+) modulated dual-functional fluorescent probe was developed. The attachment of sulfanilic acid and glutathione onto GQDs through amide linkage to obtained the functionalized graphene quantum dots (termed as SSGQDs). The SSGQDs exhibit dramatically enhanced green fluorescence compared with GQDs. And the fluorescence of SSGQDs was found to be effectively quenched by Cu2+ via aggregation kinetics with the formation of SSGQDs-Cu(II) complex. Sulfide anions (S2−) exhibits a good capacity to remove Cu2+ from SSGQDs and dissociated SSGQDs-Cu(II) complex, as a result the fluorescence of SSGQDs was turned on again. Moreover, the introduction of ascorbic acid (AA) could also induce the fluorescence recovery, because it could reduce Cu2+ into Cu+ and result in the destruction of the SSGQDs-Cu(II) complex. This method can be used for the selective analysis of S2− and AA down to 12.6nM and 20.3nM, respectively. Furthermore, the applications of this probe for S2− and AA determination in lake water samples and beverage sample have been demonstrated with satisfactory results.

Selective and Real-Time Detection of Nitric Oxide by a Two-Photon Fluorescent Probe in Live Cells and Tissue Slices.

Nitric oxide (NO) is an important signaling molecule involved in many physiological and pathological processes. To understand these NO-mediated processes, it is a key to develop rapid and specific detection methods for NO. In the past 2 decades, numerous excellent fluorescent probes for NO have been designed; however, it still remains limitations such as slow response, low selectivity, and short excitation wavelength (<600 nm). In this Article, a two-photon fluorescent probe, NO-QA5, has been developed with 3-dimethylaminophenyl linking at the 6-position of 5-aminoquinoline as both the active site and prefluorophore for detection of NO. The nonfluorescent NO-QA5 can fast react with NO via a diazonium intermediate to generate two azoic regioisomers, one of which exhibits intramolecular charge transfer (ICT) emission, and two-photon absorption behavior (δΦ = 57 GM), giving a turn-on fluorescence rapid response. The sensing reaction is pH-insensitive in the range of 6-11 and highly selective and well sensitive (LOD = 15 nM), possible undergoing the same intermediate diazonium with the reaction under diazotization condition (NaNO2/HCl). Also, as a nitrite fluorescent probe NO-QA5 exhibits highly sensitive (LOD = 7 nM). Therefore, NO-QA5 can serve as a dual functional fluorescent probe for NO and NO2-. Furthermore, NO-QA5 as a specific imaging agent has been demonstrated by achieving both exogenous and endogenous detections of NO in living cells under both one- and two-photon excitation and high resolution in tissue slices under two-photon excitation.

Simultaneous detection of two hepatocellar carcinoma-related microRNAs using a clever single-labeled fluorescent probe

The simultaneous detection of two important microRNAs (miRNAs) can potentially evaluate pathological states. The simultaneous detection of miRNA-26a and miRNA-122 is proposed in this study using a cleverly designed single-labeled, dual-functional fluorescent probe with a 2-aminopurine as a fluorophore, which is a G-quadruplex single-stranded DNA. The probe can partly complement cDNA-1 and cDNA-2. cDNA-1 and cDNA-2 are complementary strands of miRNA-26a and miRNA-122, respectively. When the target miRNAs are added simultaneously, these cDNA (cDNA-1 and cDNA-2) can be competed off from the cDNA∖probe duplex to form a cDNA∖RNA heteroduplex. The probe is released and the fluorescent signal is increased. The detection limits of miRNA-26a and miRNA-122 are both 2.5 nM, and their wide linear which ranges from 2.5 to 500 nM are achieved using the assay. This method has potential practical applications.

Dual-functional fluorescent probe responds to hypochlorous acid and SO2 derivatives with different fluorescence signals

In view of the important roles of reactive oxygen species (ROS) and reactive sulfur species (RSS) in the complex signal transduction and oxidation pathways, fluorescent probes that are able to display distinct signals to hypochlorous acid and SO2 derivatives are highly valuable. Herein, a novel dual-functional probe (DFP) as an efficient single fluorescent-molecule which can respond to HClO and HSO3− with two different sets of fluorescence signals was presented. The DFP displayed desired properties such as high specificity, suitable sensitivity, appreciable water solubility and stability. The sensing mechanism was confirmed by high-resolution mass spectroscopy analysis and 1H NMR spectrometry analysis. Moreover, as a biocompatible molecule, the DFP has been successfully applied for the detection of HClO in living cells with a dual-channel mode. Therefore, the present work established a novel strategy for monitoring the multiple ROS and RSS species using a single fluorescent probe and the DFP is promising as a molecular tool to investigate the production and dynamics of HClO and HSO3− in the complex interaction networks of the living system.

Dual-functional probes for sequential thiol and redox homeostasis sensing in live cells.

A new type of resorufin-based dual-functional fluorescent probe whose fluorescence emission features are sensitive to thiol compounds and redox homeostasis was developed. Thiols-triggered nucleophilic substitution of the probes converts the nonfluorescent probe to the highly fluorescent resorufin moiety; the released resorufin not only enables fluorescence signaling specific for thiol compounds but functions as a redox indicator with sensitive colorimetric and fluorescence emission change upon redox variation. Preliminary fluorescence imaging experiments have revealed the biocompatibility of the as-prepared probes and validated their practicability for thiol sensing and redox homeostasis mapping in living cells.

Carbamodithioate-based dual functional fluorescent probe for Hg(2+) and S(2-).

Carbamodithioate-based compound T1 was designed and synthesized as a dual-functional probe for Hg(2+) ions and S(2-) anions. The underlying signaling mechanism was intramolecular charge transfer (ICT). It could serve as a direct probe towards Hg(2+) ions through "on-off" fluorescence changes and an indirect probe towards S(2-) anions through "on-off-on" fluorescence changes.

A dual functional fluorescent probe for glioma imaging mediated by Blood-brain barrier penetration and glioma cell targeting

Glioma is a huge threat for human being because it was hard to be completely removed owing to both the infiltrating growth of glioma cells and integrity of blood brain barrier. Thus effectively imaging the glioma cells may pave a way for surgical removing of glioma. In this study, a fluorescent probe, Cy3, was anchored onto the terminal of AS1411, a glioma cell targeting aptamer, and then TGN, a BBB targeting peptide, was conjugated with Cy3-AS1411 through a PEG linker. The production, named AsT, was characterized by gel electrophoresis, 1H NMR and FTIR. In vitro cellular uptake and glioma spheroid uptake demonstrated the AsT could not only be uptaken by both glioma and endothelial cells, but also penetrate through endothelial cell monolayer and uptake by glioma spheroids. In vivo, AsT could effectively target to glioma with high intensity. In conclusion, AsT could be used as an effective glioma imaging probe.