WorldWideScience

Sample records for fluorescent probes polarity

  1. Polarization of fluorescence: a probe of molecular autoionization

    International Nuclear Information System (INIS)

    Leroi, G.E.; Dehmer, J.L.; Parr, A.C.; Poliakoff, E.D.

    1983-01-01

    The polarization of fluorescence from excited-state molecular photoions provides a direct probe of the photoionization dynamics and the symmetry signatures of autoionizing resonances. Measurements on CO 2 and CS 2 are presented as examples

  2. A sensitive fluorescent probe for the polar solvation dynamics at protein-surfactant interfaces.

    Science.gov (United States)

    Singh, Priya; Choudhury, Susobhan; Singha, Subhankar; Jun, Yongwoong; Chakraborty, Sandipan; Sengupta, Jhimli; Das, Ranjan; Ahn, Kyo-Han; Pal, Samir Kumar

    2017-05-17

    Relaxation dynamics at the surface of biologically important macromolecules is important taking into account their functionality in molecular recognition. Over the years it has been shown that the solvation dynamics of a fluorescent probe at biomolecular surfaces and interfaces account for the relaxation dynamics of polar residues and associated water molecules. However, the sensitivity of the dynamics depends largely on the localization and exposure of the probe. For noncovalent fluorescent probes, localization at the region of interest in addition to surface exposure is an added challenge compared to the covalently attached probes at the biological interfaces. Here we have used a synthesized donor-acceptor type dipolar fluorophore, 6-acetyl-(2-((4-hydroxycyclohexyl)(methyl)amino)naphthalene) (ACYMAN), for the investigation of the solvation dynamics of a model protein-surfactant interface. A significant structural rearrangement of a model histone protein (H1) upon interaction with anionic surfactant sodium dodecyl sulphate (SDS) as revealed from the circular dichroism (CD) studies is nicely corroborated in the solvation dynamics of the probe at the interface. The polarization gated fluorescence anisotropy of the probe compared to that at the SDS micellar surface clearly reveals the localization of the probe at the protein-surfactant interface. We have also compared the sensitivity of ACYMAN with other solvation probes including coumarin 500 (C500) and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran (DCM). In comparison to ACYMAN, both C500 and DCM fail to probe the interfacial solvation dynamics of a model protein-surfactant interface. While C500 is found to be delocalized from the protein-surfactant interface, DCM becomes destabilized upon the formation of the interface (protein-surfactant complex). The timescales obtained from this novel probe have also been compared with other femtosecond resolved studies and molecular dynamics simulations.

  3. Nine New Fluorescent Probes

    Science.gov (United States)

    Lin, Tsung-I.; Jovanovic, Misa V.; Dowben, Robert M.

    1989-06-01

    Absorption and fluorescence spectroscopic studies are reported here for nine new fluorescent probes recently synthesized in our laboratories: four pyrene derivatives with substituents of (i) 1,3-diacetoxy-6,8-dichlorosulfonyl, (ii) 1,3-dihydroxy-6,8-disodiumsulfonate, (iii) 1,3-disodiumsulfonate, and (iv) l-ethoxy-3,6,8-trisodiumsulfonate groups, and five [7-julolidino] coumarin derivatives with substituents of (v) 3-carboxylate-4-methyl, (vi) 3- methylcarboxylate, (vii) 3-acetate-4-methyl, (viii) 3-propionate-4-methyl, and (ix) 3-sulfonate-4-methyl groups. Pyrene compounds i and ii and coumarin compounds v and vi exhibit interesting absorbance and fluorescence properties: their absorption maxima are red shifted compared to the parent compound to the blue-green region, and the band width broadens considerably. All four blue-absorbing dyes fluoresce intensely in the green region, and the two pyrene compounds emit at such long wavelengths without formation of excimers. The fluorescence properties of these compounds are quite environment-sensitive: considerable spectral shifts and fluorescence intensity changes have been observed in the pH range from 3 to 10 and in a wide variety of polar and hydrophobic solvents with vastly different dielectric constants. The high extinction and fluorescence quantum yield of these probes make them ideal fluorescent labeling reagents for proteins, antibodies, nucleic acids, and cellular organelles. The pH and hydrophobicity-dependent fluorescence changes can be utilized as optical pH and/or hydrophobicity indicators for mapping environmental difference in various cellular components in a single cell. Since all nine probes absorb in the UV, but emit at different wavelengths in the visible, these two groups of compounds offer an advantage of utilizing a single monochromatic light source (e.g., a nitrogen laser) to achieve multi-wavelength detection for flow cytometry application. As a first step to explore potential application in

  4. Fluorescence study of arene probe microenvironment in the intraparticle void volume of zeolites interfaced with bathing polar solvents.

    Science.gov (United States)

    Ellison, Eric H; Moodley, Deshi; Hime, Joseph

    2006-03-16

    Fluorescence methodologies have been utilized to examine micropolarity, intramolecular motion, and singlet quenching in the intraparticle void volume of zeolites X, Y, and ultrastable Y (USY) interfaced with bathing polar solvents. Micropolarity was assessed from the 3-to-1 band ratio (III/I) of the fluorescence spectrum of pyrene (PY) and from lambda(max) of the fluorescence spectrum of 1-pyrenecarboxaldehyde (1-PCA). In zeolites bathed in anhydrous solvents, both PY and 1-PCA reported increased micropolarity according to the trend USY nitrocompounds dissolved in solvents bathing the zeolite was examined by a time-resolved approach. For all of the quenchers and solvents studied, quenching was more efficient in USY compared to NaX and NaY. Interestingly, the rate of O2 quenching in USY-MeOH was only 12 times lower than that in bulk MeOH. In contrast, in NaY-MeOH and NaX-MeOH the rate of O2 quenching was too low to be measured. The rate constants in these systems were therefore taken as the rate constant for diffusion-controlled quenching of trapped electrons measured previously. These values were 600 times and 10(5) times lower than the rate of fluorescence quenching in USY-MeOH, respectively. The O2 quenching studies show that dispersive interactions of polar solvents with the cavity walls dominate in USY because of the hydrophobic nature of the USY surface. In NaX and NaY, stronger ion-dipole and hydrogen bonding interactions dominate and lead to more restricted access and lowered quenching efficiency. Perrin (or static) quenching of pyrene fluorescence was also examined to infer the concentration of nitromethane (NM) in the void volume of NaX and NaY bathed in MeOH, ACN, or H2O. The results indicate that access of NM to the interior of NaY is more inhibited in ACN compared to MeOH, presumably because of the higher dipole moment of ACN and its resulting stronger association with the zeolite surface. At similar levels of static quenching equated to a similar NM

  5. Fluorescence confocal polarizing microscopy

    Indian Academy of Sciences (India)

    Much of the modern understanding of orientational order in liquid crystals (LCs) is based on polarizing microscopy (PM). A PM image bears only two-dimensional (2D) information, integrating the 3D pattern of optical birefringence over the path of light. Recently, we proposed a technique to image 3D director patterns by ...

  6. [Fluorescence polarization immunoassay of ractopamine].

    Science.gov (United States)

    Zvereva, E A; Shpakova, N A; Zherdev, A V; Kiu, L; Xu, C; Eremin, S A; Dzantiev, B B

    2016-01-01

    A technique was developed for fluorescence polarization immunoassay (FPIA) of ractopamine, a toxic low molecular weight nonsteroidal growth regulator belonging to the most controlled contaminants of food products of animal origin. The assay is based on the competition between a sample containing ractopamine and ractopamine–fluorophore conjugate for binding to antibodies. The competition is monitored via changes in the degree of fluorescence polarization for plane-polarized excitation light, which differs for the free and antibody-bound forms of the conjugate. The optimal assay conditions were established, ensuring a high accuracy and minimal detection limit. The developed assay demonstrated a detection limit of 1 ng/mL and a range of detectable concentrations of 2.3–50 ng/mL, which met the requirements of sanitary control. The duration of the analysis was 10 min. The possible application of the developed FPIA was demonstrated with testing of turkey meat. The speed and simplicity of the proposed assay define its efficiency as a screening tool for safety of foods.

  7. Monitoring membrane hydration with 2-(dimethylamino)-6-acylnaphtalenes fluorescent probes

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2015-01-01

    comparative studies. This chapter presents a short historical overview about these fluorescent reporters, discusses on different models proposed to explain their sensitivity to membrane hydration, and includes relevant examples from experiments performed in artificial and biological membranes......., were used to study membrane lateral structure and associated dynamics. Once incorporated into membranes, the (nanosecond) fluorescent decay of these probes is strongly affected by changes in the local polarity and relaxation dynamics of restricted water molecules existing at the membrane....../water interface. For instance, when glycerophospholipid containing membranes undertake a solid ordered (gel) to liquid disordered phase transition the fluorescence emission maximum of these probes shift ~ 50 nm with a significant change in their fluorescence lifetime. Furthermore, the fluorescence parameters...

  8. Flow cytometry, fluorescent probes, and flashing bacteria

    NARCIS (Netherlands)

    Bunthof, C.J.

    2002-01-01


    Key words: fluorescent probes, flow cytometry, CSLM, viability, survival, microbial physiology, lactic acid bacteria, Lactococcus lactis , Lactobacillus plantarum , cheese, milk,

  9. Azaphthalocyanines: Red Fluorescent Probes for Cations

    Czech Academy of Sciences Publication Activity Database

    Nováková, V.; Lochman, L.; Zajícová, I.; Kopecký, K.; Miletin, M.; Lang, Kamil; Kirakci, Kaplan; Zimcik, P.

    2013-01-01

    Roč. 19, č. 16 (2013), s. 5025-5028 ISSN 0947-6539 R&D Projects: GA ČR GAP208/10/1678 Institutional support: RVO:61388980 Keywords : crown compounds * fluorescent probes * phthalocyanine s * potassium * sodium Subject RIV: CA - Inorganic Chemistry Impact factor: 5.696, year: 2013

  10. Genetically encoded fluorescent probe to visualize phosphatidylinositol

    Czech Academy of Sciences Publication Activity Database

    Eisenreichová, Andrea; Humpolíčková, Jana; Bouřa, Evžen

    2017-01-01

    Roč. 284, Suppl 1 (2017), s. 364-365 ISSN 1742-464X. [FEBS Congress /42./ From Molecules to Cells and Back. 10.09.2017-14.09.2017, Jerusalem] R&D Projects: GA ČR GJ15-21030Y; GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : phosphatidylinositol * fluorescent probe Subject RIV: CE - Biochemistry

  11. Probing Zeolite Crystal Architecture and Structural Imperfections using Differently Sized Fluorescent Organic Probe Molecules.

    Science.gov (United States)

    Hendriks, Frank C; Schmidt, Joel E; Rombouts, Jeroen A; Lammertsma, Koop; Bruijnincx, Pieter C A; Weckhuysen, Bert M

    2017-05-05

    A micro-spectroscopic method has been developed to probe the accessibility of zeolite crystals using a series of fluorescent 4-(4-diethylaminostyryl)-1-methylpyridinium iodide (DAMPI) probes of increasing molecular size. Staining large zeolite crystals with MFI (ZSM-5) topology and subsequent mapping of the resulting fluorescence using confocal fluorescence microscopy reveal differences in structural integrity: the 90° intergrowth sections of MFI crystals are prone to develop structural imperfections, which act as entrance routes for the probes into the zeolite crystal. Polarization-dependent measurements provide evidence for the probe molecule's alignment within the MFI zeolite pore system. The developed method was extended to BEA (Beta) crystals, showing that the previously observed hourglass pattern is a general feature of BEA crystals with this morphology. Furthermore, the probes can accurately identify at which crystal faces of BEA straight or sinusoidal pores open to the surface. The results show this method can spatially resolve the architecture-dependent internal pore structure of microporous materials, which is difficult to assess using other characterization techniques such as X-ray diffraction. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  12. Spectroscopic characterization of novel fluorescent lipid membrane probes

    International Nuclear Information System (INIS)

    Knapp, M.

    2001-11-01

    The aim of this thesis was the spectroscopic characterization of new, so far not described fluorescence markers which incorporate into ordered systems and provide information about their structure, the phase transition and aggregation. Bianthryl, Anthracen and Coumarin 6 were incorporated into liposomes formed from Lecithine, DMPC or DPPC as well as β-Cyclodextrin. The systems were characterized by means of classical-spectroscopic methods, laser-induced fluorescence and fluorescence correlation spectroscopy (FCS). Because of the prospective phyto-physical characteristics of bianthryl, i.e. the formation of a charge-separated electronic exited state this probe is particularly suitable to detect small changes of micro viscosity and local polarity of liposomes. Due to three clearly separated fluorescence lifetimes of the excited singlet state, measured for Bianthryl, three specific sites of this molecule within the phospholipid membrane were proven. Coumarin 6 incorporates likewise very well in Liposomes. The thermotrope phase transition at temperature 24,5 o C is well provable by the change of the anisotropy of fluorescence of this laser dye. By time-resolved anisotropy measurements the dynamics (rotation) was proven with high sensitivity. The thermotropic phase transition of DMPC Liposomes was detected by means of fluorescence reasonance energy transfer (FRET). A specific method for the determination of fluorescence quantum yields in strongly scattering solutions was suggested on the basis of FRET using Anthracen as energy donor and coumarin 6 as energy acceptor. For the energy transfer of Anthracen to Coumarin 6 in the gel phase of the DMPC liposomes as substantial proportion of static transfer was found. The presence of correlated donor-acceptor pairs was proven by the comparison of stationary and time-resolved fluorescence. Further more, concentration- and temperature dependent formation was found of anthracene dimers. Such dimers are formed in the gel phase of

  13. Direct probing of chromatography columns by laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    McGuffin, V.L.

    1992-12-07

    This report summarizes the progress and accomplishments of this research project from September 1, 1989 to February 28, 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe insupercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

  14. Relaxation dynamics of a polar solvent cage around a nonpolar electronically excited solvent probe. A subpicosecond laser study

    International Nuclear Information System (INIS)

    Mialocq, J.C.; Hebert, P.; Baldacchino, G.; Gustavsson, T.

    1993-01-01

    The aim of the present paper is to show that the LDS 751 unsymmetrical cyanine laser dye, highly polar in the ground state and non polar in the fluorescent excited singlet state, is a suitable solvent probe. Excitation of LDS 751 in a polar solvent with an ultrashort laser pulse suddenly annihilates the permanent dipole moment of the solute and suppresses the forces which orientate the nearby solvent molecules. The subpicosecond analysis of the Time-Dependent Fluorescence Stokes Shift (TDFSS) of LDS 751 thus enables to probe the relaxation of polar solvent molecules which can be considered as free of solute-solvent interactions. (author)

  15. Thermally sensitive dual fluorescent polymeric micelles for probing cell properties

    NARCIS (Netherlands)

    Li Feng, F.; Westphal, A.H.; Marcelis, A.T.M.; Sudhölter, E.J.R.; Cohen Stuart, M.A.; Leermakers, F.A.M.

    2011-01-01

    Dual fluorescent micelles with a hydrophobic probe (HMA) embedded in the micelle core and a hydrophilic probe (TRITC) attached on the micelle corona were prepared. These micelles can act as nanometre-sized thermal sensors. Within a short temperature range, the fluorescent emission of the micelles

  16. Fluorescence depolarization as a probe of molecular dynamics within liquid jets

    Science.gov (United States)

    Kenyon, A. J.; McCaffery, A. J.; Quintella, C. M.

    Preliminary results are presented from a study of fluorescence depolarization within a thin laminar jet of rhodamine 6 G in ethylene glycol. A large number of polarization measurements taken across the jet have enabled us to build up a detailed polarization map of the liquid flow. Relating the degree of depolarization to molecular alignment caused by the presence of shear forces within the jet, we propose that this method may be used as a sensitive probe of the molecular dynamics of liquid flow.

  17. Studies of radiation induced membrane damage in lymphocytes using fluorescent probes

    International Nuclear Information System (INIS)

    Nikesch, W.

    1974-01-01

    The fluorescent probes perylene (PER), 1-anilino-8-naphthalene sulfonic acid (ANS), and fluorescein diacetate (FDA) were used to investigate membrane changes caused by ionizing radiation. Probe response to various other perturbations (variation of pH, temperature, and salt concentration, and treatment with phythohemagglutinin (PHA) and saponins) was also investigated to better understand membrane-probe interactions. ANS was used to probe the membrane surface, PER to probe the membrane interior, and FDA to investigate membrane integrity. Polarization of fluorescent light from ANS and PER was used to investigate the microviscosity and order of the membrane surface and interior respectively. Irradiated cells (600 R) were shown to have a decreased rate of hydrolysis of FDA probably due to cytoplasmic changes effecting the enzymatic reaction. Also evident was an increase in loss of intracellular fluorescein and a decrease in PER polarization indicating that the cells have a decreased membrane integrity, possibly the result of an increased disorganization of the phospholipid hydrocarbon chains in the membrane interior. Experiments with PHA link the decreased membrane integrity with the eventual interphase death of the cells. In general it is shown that the fluorescent probes ANS, PER, and FDA provide useful ways to investigate order and microviscosity in the cell membrane surface and interior, membrane surface charges, internal membrane polarity changes, and membrane integrity. (U.S.)

  18. Flow Cytometric Applicability of Fluorescent Vitality Probes on Phytoplankton

    NARCIS (Netherlands)

    Peperzak, L.; Brussaard, C.P.D.

    2011-01-01

    The applicability of six fluorescent probes (four esterase probes: acetoxymethyl ester of Calcein [Calcein-AM], 5-chloromethylfluorescein diacetate [CMFDA], fluorescein diacetate [FDA], and 2',7'-dichlorofluorescein diacetate [H(2)DCFDA]; and two membrane probes: bis-(1,3-dibutylbarbituric acid)

  19. d-PET-controlled “off-on” Polarity-sensitive Probes for Reporting Local Hydrophilicity within Lysosomes

    Science.gov (United States)

    Zhu, Hao; Fan, Jiangli; Mu, Huiying; Zhu, Tao; Zhang, Zhen; Du, Jianjun; Peng, Xiaojun

    2016-10-01

    Polarity-sensitive fluorescent probes are powerful chemical tools for studying biomolecular structures and activities both in vitro and in vivo. However, the lack of “off-on” polarity-sensing probes has limited the accurate monitoring of biological processes that involve an increase in local hydrophilicity. Here, we design and synthesize a series of “off-on” polarity-sensitive fluorescent probes BP series consisting of the difluoroboron dippyomethene (BODIPY) fluorophore connected to a quaternary ammonium moiety via different carbon linkers. All these probes showed low fluorescence quantum yields in nonpolar solution but became highly fluorescent in polar media. BP-2, which contains a two-carbon linker and a trimethyl quaternary ammonium, displayed a fluorescence intensity and quantum yield that were both linearly correlated with solvent polarity. In addition, BP-2 exhibited high sensitivity and selectivity for polarity over other environmental factors and a variety of biologically relevant species. BP-2 can be synthesized readily via an unusual Mannich reaction followed by methylation. Using electrochemistry combined with theoretical calculations, we demonstrated that the “off-on” sensing behavior of BP-2 is primarily due to the polarity-dependent donor-excited photoinduced electron transfer (d-PET) effect. Live-cell imaging established that BP-2 enables the detection of local hydrophilicity within lysosomes under conditions of lysosomal dysfunction.

  20. Polarization-dependent responses of fluorescent indicators partitioned into myelinated axons

    Science.gov (United States)

    Micu, Ileana; Brideau, Craig; Stys, Peter K.

    2012-02-01

    Myelination, i.e. the wrapping of axons in multiple layers of lipid-rich membrane, is a unique phenomenon in the nervous systems of both vertebrates and invertebrates, that greatly increases the speed and efficiency of signal transmission. In turn, disruption of axo-myelinic integrity underlies disability in numerous clinical disorders. The dependence of myelin physiology on nanometric organization of its lamellae makes it difficult to accurately study this structure in the living state. We expected that fluorescent probes might become highly oriented when partitioned into the myelin sheath, and in turn, this anisotropy could be interrogated by controlling the polarization state of the exciting laser field used for 2-photon excited fluorescence (TPEF). Live ex vivo myelinated rodent axons were labeled with a series of lipohilic and hydrophilic fluorescenct probes, and TPEF images acquired while laser polarization was varied at the sample over a broad range of ellipticities and orientations of the major angle [see Brideau, Micu & Stys, abstract this meeting]. We found that most probes exhibited strong dependence on both the major angle of polarization, and perhaps more surprisingly, on ellipticity as well. Lipophilic vs. hydrophilic probes exhibited distinctly different behavior. We propose that polarization-dependent TPEF microscopy represents a powerful tool for probing the nanostructural architecture of both myelin and axonal cytoskeleton in a domain far below the resolution limit of visible light microscopy. By selecting probes with different sizes and physicochemical properties, distinct aspects of cellular nanoarchitecture can be accurately interrogated in real-time in living tissue.

  1. Protein recognition by a pattern-generating fluorescent molecular probe

    Science.gov (United States)

    Pode, Zohar; Peri-Naor, Ronny; Georgeson, Joseph M.; Ilani, Tal; Kiss, Vladimir; Unger, Tamar; Markus, Barak; Barr, Haim M.; Motiei, Leila; Margulies, David

    2017-12-01

    Fluorescent molecular probes have become valuable tools in protein research; however, the current methods for using these probes are less suitable for analysing specific populations of proteins in their native environment. In this study, we address this gap by developing a unimolecular fluorescent probe that combines the properties of small-molecule-based probes and cross-reactive sensor arrays (the so-called chemical 'noses/tongues'). On the one hand, the probe can detect different proteins by generating unique identification (ID) patterns, akin to cross-reactive arrays. On the other hand, its unimolecular scaffold and selective binding enable this ID-generating probe to identify combinations of specific protein families within complex mixtures and to discriminate among isoforms in living cells, where macroscopic arrays cannot access. The ability to recycle the molecular device and use it to track several binding interactions simultaneously further demonstrates how this approach could expand the fluorescent toolbox currently used to detect and image proteins.

  2. Probing lateral magnetic nanostructures by polarized GISANS

    International Nuclear Information System (INIS)

    Kentzinger, E.; Frielinghaus, H.; Ruecker, U.; Ioffe, A.; Richter, D.; Brueckel, Th.

    2007-01-01

    While structural and magnetic lateral correlations in thin film materials can be investigated at the μm length scale by neutron off-specular scattering (OSS) with polarization analysis, they can also be investigated at the nm length scale by grazing incidence small-angle scattering of polarized neutrons (polarized GISANS). We exemplify this issue showing a combined OSS and GISANS study of the lateral correlations in a remanent polarizing supermirror

  3. Probing lateral magnetic nanostructures by polarized GISANS

    Science.gov (United States)

    Kentzinger, E.; Frielinghaus, H.; Rücker, U.; Ioffe, A.; Richter, D.; Brückel, Th.

    2007-07-01

    While structural and magnetic lateral correlations in thin film materials can be investigated at the μm length scale by neutron off-specular scattering (OSS) with polarization analysis, they can also be investigated at the nm length scale by grazing incidence small-angle scattering of polarized neutrons (polarized GISANS). We exemplify this issue showing a combined OSS and GISANS study of the lateral correlations in a remanent polarizing supermirror.

  4. Nucleic acid-based fluorescent probes and their analytical potential.

    Science.gov (United States)

    Juskowiak, Bernard

    2011-03-01

    It is well known that nucleic acids play an essential role in living organisms because they store and transmit genetic information and use that information to direct the synthesis of proteins. However, less is known about the ability of nucleic acids to bind specific ligands and the application of oligonucleotides as molecular probes or biosensors. Oligonucleotide probes are single-stranded nucleic acid fragments that can be tailored to have high specificity and affinity for different targets including nucleic acids, proteins, small molecules, and ions. One can divide oligonucleotide-based probes into two main categories: hybridization probes that are based on the formation of complementary base-pairs, and aptamer probes that exploit selective recognition of nonnucleic acid analytes and may be compared with immunosensors. Design and construction of hybridization and aptamer probes are similar. Typically, oligonucleotide (DNA, RNA) with predefined base sequence and length is modified by covalent attachment of reporter groups (one or more fluorophores in fluorescence-based probes). The fluorescent labels act as transducers that transform biorecognition (hybridization, ligand binding) into a fluorescence signal. Fluorescent labels have several advantages, for example high sensitivity and multiple transduction approaches (fluorescence quenching or enhancement, fluorescence anisotropy, fluorescence lifetime, fluorescence resonance energy transfer (FRET), and excimer-monomer light switching). These multiple signaling options combined with the design flexibility of the recognition element (DNA, RNA, PNA, LNA) and various labeling strategies contribute to development of numerous selective and sensitive bioassays. This review covers fundamentals of the design and engineering of oligonucleotide probes, describes typical construction approaches, and discusses examples of probes used both in hybridization studies and in aptamer-based assays.

  5. [Development of a Fluorescence Probe for Live Cell Imaging].

    Science.gov (United States)

    Shibata, Aya

    2017-01-01

    Probes that detect specific biological materials are indispensable tools for deepening our understanding of various cellular phenomena. In live cell imaging, the probe must emit fluorescence only when a specific substance is detected. In this paper, we introduce a new probe we developed for live cell imaging. Glutathione S-transferase (GST) activity is higher in tumor cells than in normal cells and is involved in the development of resistance to various anticancer drugs. We previously reported the development of a general strategy for the synthesis of probes for detection of GST enzymes, including fluorogenic, bioluminogenic, and 19 F-NMR probes. Arylsulfonyl groups were used as caging groups during probe design. The fluorogenic probes were successfully used to quantitate very low levels of GST activity in cell extracts and were also successfully applied to the imaging of microsomal MGST1 activity in living cells. The bioluminogenic and 19 F-NMR probes were able to detect GST activity in Escherichia coli cells. Oligonucleotide-templated reactions are powerful tools for nucleic acid sensing. This strategy exploits the target strand as a template for two functionalized probes and provides a simple molecular mechanism for multiple turnover reactions. We developed a nucleophilic aromatic substitution reaction-triggered fluorescent probe. The probe completed its reaction within 30 s of initiation and amplified the fluorescence signal from 0.5 pM target oligonucleotide by 1500 fold under isothermal conditions. Additionally, we applied the oligonucleotide-templated reaction for molecular releasing and peptide detection.

  6. Direct Probes of Linearly Polarized Gluons inside Unpolarized Hadrons

    NARCIS (Netherlands)

    Boer, D.; Brodsky, S. J.; Mulders, P.J.G.; Pisano, C.

    2011-01-01

    We show that linearly polarized gluons inside unpolarized hadrons can be directly probed in jet or heavy quark pair production in electron-hadron collisions. We discuss the simplest cos2 asymmetries and estimate their maximal value, concluding that measurements of the unknown linearly polarized

  7. Phenylethynylpyrene excimer forming hybridization probes for fluorescence SNP detection

    DEFF Research Database (Denmark)

    Prokhorenko, Igor A.; Astakhova, Irina V.; Momynaliev, Kuvat T.

    2009-01-01

    Excimer formation is a unique feature of some fluorescent dyes (e.g., pyrene) which can be used for probing the proximity of biomolecules. Pyrene excimer fluorescence has previously been used for homogeneous detection of single nucleotide polymorphism (SNP) on DNA. 1-Phenylethynylpyrene (1-1-PEPy......), a photostable pyrene derivative with redshifted fluorescence, is able to form excimers (emission maximum about 500-510 nm) and is well suitable for nucleic acid labeling. We have shown the utility of 1-1-PEPy in the excimer-forming DNA probes for detection of 2144A/G and 2143A/G transitions, and 2143A...

  8. New applications of fluorescence polarization for enzyme assays and in genomics

    Science.gov (United States)

    Nikiforov, Theo; Coffin, Jill; Jeong, Sang; Simeonov, Anton; Bi, Xiahui

    2001-05-01

    We have developed new, fluorescence polarization-based approaches for performing enzyme assays in homogeneous solutions and for detecting the hybridization of peptide nucleic acids to DNA targets. In the first method, fluorescein-labeled peptides serving as protein kinase sustrates are thiophosphorylated in the presence of the ATP analog ATPγS. A sulfer-reactive biotin derivative is then added to the mixture and allowed to react with the thiophosphorylated peptide. The formation of a fluorescein-labeled, biotinylated product can be detected by measuring the fluorescence polarization signal of fluorescein upon addition of streptavidin. In the second method, fluorescein-labeled peptides are subjected to enzymatic phosphorylation, desphosphorlation, or proteollytic cleavage by protein kinases, phosphatases, and proteases. The differential binding of the enzymatic substrates and products to cationic polymers such as polyaraginine can be conveniently measured by fluorescence polarization. Finally, we have discovered that the process of hybridization of peptide nucleic acid probes (PNAs) to their target DNA molecules can be followed by measuring the fluorescence polarization of a fluorophore attached to the PNA probes. These measurements can be done either in the presence or absence of polylysine in solution. Examples of the application of this method for single nucleotide polymorphism (SNP) typing are presented.

  9. Hybrid fluorescent layer emitting polarized light

    Directory of Open Access Journals (Sweden)

    Mohammad Mohammadimasoudi

    2017-07-01

    Full Text Available Semiconductor nanorods have anisotropic absorption and emission properties. In this work a hybrid luminescent layer is produced based on a mixture of CdSe/CdS nanorods dispersed in a liquid crystal that is aligned by an electric field and polymerized by UV illumination. The film emits light with polarization ratio 0.6 (polarization contrast 4:1. Clusters of nanorods in liquid crystal can be avoided by applying an AC electric field with sufficient amplitude. This method can be made compatible with large-scale processing on flexible transparent substrates. Thin polarized light emitters can be used in LCD backlights or solar concentrators to increase the efficiency.

  10. Analysis of Cholesterol Trafficking with Fluorescent Probes

    DEFF Research Database (Denmark)

    Maxfield, Frederick R.; Wustner, Daniel

    2012-01-01

    Cholesterol plays an important role in determining the biophysical properties of biological membranes, and its concentration is tightly controlled by homeostatic processes. The intracellular transport of cholesterol among organelles is a key part of the homeostatic mechanism, but sterol transport...... that can bind to cholesterol to reveal its distribution in cells. We also discuss the use of intrinsically fluorescent sterols that closely mimic cholesterol, as well as some minimally modified fluorophore-labeled sterols. Methods for imaging these sterols by conventional fluorescence microscopy...... and by multiphoton microscopy are described. Some label-free methods for imaging cholesterol itself are also discussed briefly....

  11. Fluorescence correction in electron probe microanalysis

    International Nuclear Information System (INIS)

    Castellano, Gustavo; Riveros, J.A.

    1987-01-01

    In this work, several expressions for characteristic fluorescence corrections are computed, for a compilation of experimental determinations on standard samples. Since this correction does not take significant values, the performance of the different models is nearly the same; this fact suggests the use of the simplest available expression. (Author) [es

  12. Probing Zeolite Crystal Architecture and Structural Imperfections using Differently Sized Fluorescent Organic Probe Molecules

    NARCIS (Netherlands)

    Hendriks, Frank C.; Schmidt, Joel E.; Rombouts, Jeroen A.; Lammertsma, Koop; Bruijnincx, Pieter C.A.; Weckhuysen, Bert M.

    2017-01-01

    A micro-spectroscopic method has been developed to probe the accessibility of zeolite crystals using a series of fluorescent 4-(4-diethylaminostyryl)-1-methylpyridinium iodide (DAMPI) probes of increasing molecular size. Staining large zeolite crystals with MFI (ZSM-5) topology and subsequent

  13. Fluorescence-based Broad Dynamic Range Viscosity Probes.

    Science.gov (United States)

    Dragan, Anatoliy; Graham, August E; Geddes, Chris D

    2014-03-01

    We introduce two new fluorescent viscosity probes, SYBR Green (SG) and PicoGreen (PG), that we have studied over a broad range of viscosity and in collagen solutions. In water, both dyes have low quantum yields and excited state lifetimes, while in viscous solvents or in complex with DNA both parameters dramatically (300-1000-fold) increase. We show that in log-log scale the dependence of the dyes' quantum yield vs. viscosity is linear, the slope of which is sensitive to temperature. Application of SG and PG, as a fluorescence-based broad dynamic range viscosity probes, to the life sciences is discussed.

  14. Fluorescence confocal polarizing microscopy: Three-dimensional ...

    Indian Academy of Sciences (India)

    Much of the modern understanding of orientational order in liquid crystals (LCs) is based on polarizing microscopy (PM). A PM image bears only two-dimensional (2D) information, integrating the 3D pattern of optical birefringence over the path of light. Recently, we proposed a technique to image 3D director patterns by ...

  15. Fluorescence confocal polarizing microscopy: Three-dimensional ...

    Indian Academy of Sciences (India)

    Abstract. Much of the modern understanding of orientational order in liquid crystals (LCs) is based on polarizing microscopy (PM). A PM image bears only two-dimensional (2D) information, integrating the 3D pattern of optical birefringence over the path of light. Recently, we proposed a technique to image 3D director ...

  16. Fluorescence confocal polarizing microscopy: Three-dimensional ...

    Indian Academy of Sciences (India)

    cholesterics, polarization of both ordinary and extraordinary waves follows the local director (the so-called Mauguin regime) [28]. This effect must be taken into account while interpreting the FCPM images for samples with twist deformations, especially when the twist scale is supra-micron and light propagates along the twist ...

  17. A coumarin-based colorimetric fluorescent probe for hydrogen sulfide

    Indian Academy of Sciences (India)

    H2S) is presented. This 'off–on' probe exhibited high selectivity ... beneficial for the design of fluorescence sensors, which result in ON-OFF, OFF-ON or ratiometric ... The initial nucleophilic attack of H2S would lead to an intermediate thiol, which ...

  18. A simple and sensitive fluorescent probe for specific detection of ...

    Indian Academy of Sciences (India)

    Afluorescent probe, with simplicity of structure and convenience of synthesis, is capable of detecting cysteine over other biothiols, such as homocysteine and glutathione. The detection limit of 60nM and 190-fold increase in fluorescence intensity offer advantage for detection of Cys in biological systems. Furthermore, the ...

  19. Direct Probing of Polarization Charge at Nanoscale Level

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Owoong [Sungkyunkwan Univ., Suwon (Republic of Korea). School of Advanced Materials and Engineering; Seol, Daehee [Sungkyunkwan Univ., Suwon (Republic of Korea). School of Advanced Materials and Engineering; Lee, Dongkyu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Han, Hee [Korea Research Inst. of Standards and Science (KRISS), Daejeon (South Korea); Lindfors-Vrejoiu, Ionela [Univ. of Cologne (Germany). Physics Inst.; Lee, Woo [Korea Research Inst. of Standards and Science (KRISS), Daejeon (South Korea); Jesse, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences; Lee, Ho Nyung [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Kalinin, Sergei V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences; Alexe, Marin [Univ. of Warwick, Coventry (United Kingdom). Dept. of Physics; Kim, Yunseok [Sungkyunkwan Univ., Suwon (Republic of Korea). School of Advanced Materials and Engineering

    2017-11-14

    Ferroelectric materials possess spontaneous polarization that can be used for multiple applications. Owing to a long-term development of reducing the sizes of devices, the preparation of ferroelectric materials and devices is entering the nanometer-scale regime. In order to evaluate the ferroelectricity, there is a need to investigate the polarization charge at the nanoscale. Nonetheless, it is generally accepted that the detection of polarization charges using a conventional conductive atomic force microscopy (CAFM) without a top electrode is not feasible because the nanometer-scale radius of an atomic force microscopy (AFM) tip yields a very low signal-to-noise ratio. But, the detection is unrelated to the radius of an AFM tip and, in fact, a matter of the switched area. In this work, the direct probing of the polarization charge at the nanoscale is demonstrated using the positive-up-negative-down method based on the conventional CAFM approach without additional corrections or circuits to reduce the parasitic capacitance. The polarization charge densities of 73.7 and 119.0 µC cm-2 are successfully probed in ferroelectric nanocapacitors and thin films, respectively. The results we obtained show the feasibility of the evaluation of polarization charge at the nanoscale and provide a new guideline for evaluating the ferroelectricity at the nanoscale.

  20. Recent Advances in Macrocyclic Fluorescent Probes for Ion Sensing

    Directory of Open Access Journals (Sweden)

    Joseph K.-H. Wong

    2017-01-01

    Full Text Available Small-molecule fluorescent probes play a myriad of important roles in chemical sensing. Many such systems incorporating a receptor component designed to recognise and bind a specific analyte, and a reporter or transducer component which signals the binding event with a change in fluorescence output have been developed. Fluorescent probes use a variety of mechanisms to transmit the binding event to the reporter unit, including photoinduced electron transfer (PET, charge transfer (CT, Förster resonance energy transfer (FRET, excimer formation, and aggregation induced emission (AIE or aggregation caused quenching (ACQ. These systems respond to a wide array of potential analytes including protons, metal cations, anions, carbohydrates, and other biomolecules. This review surveys important new fluorescence-based probes for these and other analytes that have been reported over the past five years, focusing on the most widely exploited macrocyclic recognition components, those based on cyclam, calixarenes, cyclodextrins and crown ethers; other macrocyclic and non-macrocyclic receptors are also discussed.

  1. A Fluorescent Probe to Measure DNA Damage and Repair.

    Directory of Open Access Journals (Sweden)

    Allison G Condie

    Full Text Available DNA damage and repair is a fundamental process that plays an important role in cancer treatment. Base excision repair (BER is a major repair pathway that often leads to drug resistance in DNA-targeted cancer chemotherapy. In order to measure BER, we have developed a near infrared (NIR fluorescent probe. This probe binds to a key intermediate, termed apurinic/apyrimidinic (AP site, in the BER pathway where DNA damage and repair occurs. We have developed an assay to show the efficacy of the probe binding to AP sites and have shown that it can distinguish AP sites in DNA extract from chemotherapy treated cells. This probe has potential application in monitoring patient response to chemotherapy and evaluating new drugs in development.

  2. Polarized front-face fluorescence for muscle tissue structure evaluation

    Science.gov (United States)

    Luc, C.; Clerjon, S.; Peyrin, F.; Lepetit, J.

    2008-05-01

    The fluorescence anisotropy of a rigid medium is a consequence of photoselection of fluorophores and their orientations. This makes it possible to use polarized front-face fluorescence to provide structural information on biological tissues like muscle. Tryptophan is the major intrinsic fluorophore in muscle. It is embedded in proteins which act as building blocks for muscle structuration because of their preferential alignment. Our working hypothesis is that when the arrangement of the proteins changes, there are concomitant changes in fluorescence anisotropy parameters. Our research is directed toward evaluating muscle structure and its evolution post mortem. We report a theoretical simple model of tryptophan fluorescence and an experimental method to measure the fluorescence anisotropy of biological opaque tissues. Instrumental and optical considerations have to be taken into account in experiments on front-face polarization to make certain of measurement accuracy. Therefore, we present a detailed report on the adjustments and corrections made on a conventional L-spectrofluorimeter to adapt it to fluorescence anisotropy measurements on biological tissues. Data from several experiments demonstrate how the method is able to show muscle structure modifications. We show how it is possible to fit experimental data with the model developed in order to obtain structural information.

  3. Fluorescent Probes for Analysis and Imaging of Monoamine Oxidase Activity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dokyoung; Jun, Yong Woong; Ahn, Kyo Han [POSTECH, Pohang (Korea, Republic of)

    2014-05-15

    Monoamine oxidases catalyze the oxidative deamination of dietary amines and amine neurotransmitters, and assist in maintaining the homeostasis of the amine neurotransmitters in the brain. Dysfunctions of these enzymes can cause neurological and behavioral disorders including Parkinson's and Alzheimer's diseases. To understand their physiological roles, efficient assay methods for monoamine oxidases are essential. Reviewed in this Perspective are the recent progress in the development of fluorescent probes for monoamine oxidases and their applications to enzyme assays in cells and tissues. It is evident that still there is strong need for a fluorescent probe with desirable substrate selectivity and photophysical properties to challenge the much unsolved issues associated with the enzymes and the diseases.

  4. Fluorescent nanodiamonds as non-photobleachable responsive probes

    Czech Academy of Sciences Publication Activity Database

    Cígler, Petr

    2016-01-01

    Roč. 14, č. 5 (2016), s. 232 ISSN 2336-7202. [Sjezd českých a slovenských chemických společností /68./. 04.09.2016-07.09.2016, Praha] R&D Projects: GA ČR(CZ) GA16-16336S Institutional support: RVO:61388963 Keywords : fluorescent nanodiamonds * FNDs * probes Subject RIV: CG - Electrochemistry

  5. FLOW CYTOMETRIC APPLICABILITY OF FLUORESCENT VITALITY PROBES ON PHYTOPLANKTON1.

    Science.gov (United States)

    Peperzak, Louis; Brussaard, Corina P D

    2011-06-01

    The applicability of six fluorescent probes (four esterase probes: acetoxymethyl ester of Calcein [Calcein-AM], 5-chloromethylfluorescein diacetate [CMFDA], fluorescein diacetate [FDA], and 2',7'-dichlorofluorescein diacetate [H 2 DCFDA]; and two membrane probes: bis-(1,3-dibutylbarbituric acid) trimethine oxonol [DiBAC 4 (3)] and SYTOX-Green) as vitality stains was tested on live and killed cells of 40 phytoplankton strains in exponential and stationary growth phases, belonging to 12 classes and consisting of four cold-water, 26 temperate, and four warm-water species. The combined live/dead ratios of all six probes indicated significant differences between the 12 plankton classes (P live/dead ratios of FDA and CMFDA were not significantly different from each other, and both performed better than Calcein-AM and H 2 DCFDA (P live/dead ratios) among all six probes belonged to nine genera from six classes of phytoplankton. In conclusion, FDA, CMFDA, DIBAC 4 (3), and SYTOX-Green represent a wide choice of vitality probes in the study of phytoplankton ecology, applicable in many species from different algal classes, originating from different regions and at different stages of growth. © 2011 Phycological Society of America.

  6. Design and Evaluation of Novel Polymyxin Fluorescent Probes

    Directory of Open Access Journals (Sweden)

    Bo Yun

    2017-11-01

    Full Text Available Polymyxins (polymyxin B and colistin are cyclic lipopeptide antibiotics that serve as a last-line defence against Gram-negative “superbugs”. In the present study, two novel fluorescent polymyxin probes were designed through regio-selective modifications of the polymyxin B core structure at the N-terminus and the hydrophobic motif at positions 6 and 7. The resulting probes, FADDI-285 and FADDI-286 demonstrated comparable antibacterial activity (MICs 2–8 mg/L to polymyxin B and colistin (MICs 0.5–8 mg/L against a panel of gram-negative clinical isolates of Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa. These probes should prove to be of considerable utility for imaging cellular uptake and mechanistic investigations of these important last-line antibiotics.

  7. Excited state hydrogen bonding fluorescent probe: Role of structure and environment

    International Nuclear Information System (INIS)

    Dey, Debarati; Sarangi, Manas Kumar; Ray, Angana; Bhattacharyya, Dhananjay; Maity, Dilip Kumar

    2016-01-01

    An environment sensitive fluorescent probe, 11-benzoyl-dibenzo[a,c]phenazine (BDBPZ), has been synthesized and characterized that acts via excited state hydrogen bonding (ESHB). On interaction with hydrogen bond donating solvents the fluorescence intensity of BDBPZ increases abruptly with a concomitant bathochromic shift. The extent of fluorescence increment and the red-shift of λ max depend on hydrogen bond donating ability of the solvent associated. ESHB restricts the free rotation of the benzoyl group and hence blocks the non-radiative deactivation pathway. BDBPZ forms an exciplex with organic amine in nonpolar medium that readily disappears on increasing the polarity of the solvent. In polar environment the fluorescence of both the free molecule and excited state hydrogen bonded species are quenched on addition of amine unlike its parent dibenzo[a,c]phenazine (DBPZ), that remains very much inaccessible towards the solvent as well as quencher molecules due to its structure. This newly synthesized derivative BDBPZ is much more interactive due to the benzoyl group that is flanked outside the skeletal aromatic rings of DBPZ, which helps to sense the environment properly and thus shows better ESHB capacity than DBPZ.

  8. Time-resolved spectroscopy of the probe fluorescence in the study of human blood protein dynamic structure on SR beam

    International Nuclear Information System (INIS)

    Dobretsov, G.E.; Kurek, N.K.; Syrejshchikova, T.I.; Yakimenko, M.N.; Clarke, D.T.; Jones, G.R.; Munro, I.H.

    2000-01-01

    Time-resolved spectroscopy on the SRS of the Daresbury Laboratory was used for the study of the human serum lipoproteins and human blood albumins with fluorescent probes K-37 and K-35, developed in Russia. The probe K-37 was found sensitive to the difference in dynamic properties of the lipid objects. Two sets of the parameters were used for the description of lipid dynamic structure: (1) time-resolved fluorescence spectra and (2) time-resolved fluorescence depolarization as a function of rotational mobility of lipid molecules. Each measured dynamic parameter reflected the monotonous changes of dynamic properties in the range: lipid spheres-very low density lipoproteins-low density lipoproteins-high density lipoproteins-phospholipid liposomes. The range is characterized by the increase of the ratio polar/ nonpolar lipids. Thus, time-resolved fluorescence could be used to detect some structural modifications in lipoproteins related to atherosclerosis and subsequent cardiovascular diseases development

  9. DNA-functionalized gold nanoparticle-based fluorescence polarization for the sensitive detection of silver ions.

    Science.gov (United States)

    Wang, Gongke; Wang, Shuangli; Yan, Changling; Bai, Guangyue; Liu, Yufang

    2018-04-05

    Despite their practical applications, Ag + ions are environmental pollutants and affect human health. So the effective detection methods of Ag + ions are imperative. Herein, we developed a simple, sensitive, selective, and cost-effective fluorescence polarization sensor for Ag + detection in aqueous solution using thiol-DNA-functionalized gold nanoparticles (AuNPs). In this sensing strategy, Ag + ions can specifically interact with a cytosine-cytosine (CC) mismatch in DNA duplexes and form stable metal-mediated cytosine-Ag + -cytosine (C-Ag + -C) base pairs. The formation of the C-Ag + -C complex results in evident changes in the molecular volume and fluorescence polarization signal. To achieve our aims, we prepared two complementary DNA strands containing C-base mismatches (probe A: 5'-SH-A 10 -TACCACTCCTCAC-3' and probe B: 5'-TCCTCACCAGTCCTA-FAM-3'). The stable hybridization between probe A and probe B occurs with the formation of the C-Ag + -C complex in the presence of Ag + ions, leading to obvious fluorescence quenching in comparison to the system without AuNP enhancement. The assay can be used to identify nanomolar levels of Ag + within 6 min at room temperature, and has extremely high specificity for Ag + , even in the presence of higher concentrations of interfering metal ions. Furthermore, the sensor was successfully applied to the detection of Ag + ions in environmental water samples and showed excellent selectivity and high sensitivity, implying its promising application in the future. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Fluorescence polarization study of lipids and membranes prepared from brain hemispheres of a hibernating mammal.

    Science.gov (United States)

    Montaudon, D; Robert, J; Canguilhem, B

    1984-02-29

    The physical behavior of total lipids, microsomes and microsomal lipids prepared from brain hemispheres of European Hamsters (Cricetus cricetus) was approached by the measure of the fluorescence polarization of the probe 1,6-diphenyl 1,3,5-hexatriene. We compare in this study the results obtained for two critical periods for a hibernator: winter (torpid state) and summer (active state). An increase in fluidity was noticed in the winter lipid and membrane preparations. The difference was however of very low magnitude, suggesting that only the microenvironment of some proteins was involved, rather than the bulk membrane fluidity.

  11. Sensitive determination of nucleic acids using organic nanoparticle fluorescence probes

    Science.gov (United States)

    Zhou, Yunyou; Bian, Guirong; Wang, Leyu; Dong, Ling; Wang, Lun; Kan, Jian

    2005-06-01

    This paper describes the preparation of organic nanoparticles by reprecipitation method under sonication and vigorous stirring. Transmission electron microscopy (TEM) was used to characterize the size and size distribution of the luminescent nanoparticles. Their average diameter was about 25 nm with a size variation of ±18%. The fluorescence decay lifetime of the nanoparticles also was determined on a self-equipped fluorospectrometer with laser light source. The lifetime (˜0.09 μs) of nanoparticles is about three times long as that of the monomer. The nanoparticles were in abundant of hydrophilic groups, which increased their miscibility in aqueous solution. These organic nanoparticles have high photochemical stability, excellent resistance to chemical degradation and photodegradation, and a good fluorescence quantum yield (25%). The fluorescence can be efficiently quenched by nucleic acids. Based on the fluorescence quenching of nanoparticles, a fluorescence quenching method was developed for determination of microamounts of nucleic acids by using the nanoparticles as a new fluorescent probe. Under optimal conditions, maximum fluorescence quenching is produced, with maximum excitation and emission wavelengths of 345 and 402 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4-19.0 μg ml -1 for calf thymus DNA (ct-DNA) and 0.3-19.0 μg ml -1 for fish sperm DNA (fs-DNA). The corresponding detection limits are 0.25 μg ml -1 for ct-DNA and 0.17 μg ml -1 for fs-DNA. The relative standard deviation of six replicate measurements is 1.3-2.1%. The method is simple, rapid and sensitive with wide linear range. The recovery and relative standard deviation are very satisfactory.

  12. Coumarin-Rhodamine Hybrids-Novel Probes for the Optical Measurement of Viscosity and Polarity.

    Science.gov (United States)

    Scholz, Norman; Jadhav, Amol; Shreykar, Milind; Behnke, Thomas; Nirmalananthan, Nithiya; Resch-Genger, Ute; Sekar, Nagaiyan

    2017-11-01

    A comprehensive systematic study of absorption and fluorescence properties in solvents of varying viscosity and polarity of three novel and red-emitting coumarin-rhodamine hybrid derivatives with differences in the rigidity of their substituents is presented. This includes ethanol-polyethylene glycol, toluene-polyethylene glycol, and toluene-paraffin mixtures. Moreover, protonation-induced effects on the spectroscopic properties are studied. A viscosity-induced emission enhancement was observed for all coumarin-rhodamine hybrid derivatives. MCR2 bearing a julolidine donor showed the expected low sensitivity to viscosity whereas MCR3 with its freely rotatable diphenylamino substituent revealed a particularly pronounced sensitivity to this parameter. Moreover, MCR2 shows an enhancement in emission in the open, i.e., protonated form in conjunction with a largely Stokes shift fluorescence in the deep red spectral region. This enables the application of these dyes as viscosity sensors and as far red emitting pH-sensitive probes.

  13. Retarded Local Dynamics of Single Fluorescent Probes in Polymeric Glass due to Interaction Strengthening

    Science.gov (United States)

    Zhang, Hao; Yang, Jingfa; Zhao, Jiang

    The effect of strengthening of interaction between single fluorescent probes and polymer matrix to the probes dynamics is investigated using single molecule fluorescence defocus microscopy. By introducing multiple hydroxyl groups to the fluorescent probes, which builds up hydrogen bonds between the probe and polymer matrix, the dynamics is discovered to be retarded. This is evidenced by the lowering of the frequency of the vibrational modes in the power spectra of the rotation trajectories of individual fluorescent probes, and also by the lowering of population of rotating probes. The results show that by strengthening the probe-matrix interaction, the local dynamics detected by the probes is equivalent to that detected by a bigger probe, due to the enhanced friction between the probe and the polymer matrix. the National Basic Research Program of China (2012CB821500).

  14. A 282 GHz Probe for Dynamic Nuclear Polarization

    DEFF Research Database (Denmark)

    Rybalko, Oleksandr; Bowen, Sean; Zhurbenko, Vitaliy

    of the coil is976 MHz. A magnetic field distribution at 108 MHz and 430 MHz was calculated for the RF coil, the results revealedgood homogeneity and intensity along x,y,z axes. Figure 1 shows the general view of the probe and cross section through the microwave container with field distribution. Operating......Introduction In DNP, microwave irradiation of a sample facilitates the transfer of spin polarization from electrons tonuclei. One of the way to improve the DNP enhancement is to transfer microwave power from the mm-wave source tothe sample more effectively. Several methods and techniques...... to efficiently transport microwave energy from the microwave source to the sample have been developed. For example, a corrugated waveguide allows to deliver mm-wave energy from external source to the probe with minimum losses1.The conventional approach at high frequencies is to irradiate the sample directly from...

  15. ESIPT-Based Photoactivatable Fluorescent Probe for Ratiometric Spatiotemporal Bioimaging

    Directory of Open Access Journals (Sweden)

    Xiaohong Zhou

    2016-10-01

    Full Text Available Photoactivatable fluorophores have become an important technique for the high spatiotemporal resolution of biological imaging. Here, we developed a novel photoactivatable probe (PHBT, which is based on 2-(2-hydroxyphenylbenzothiazole (HBT, a small organic fluorophore known for its classic luminescence mechanism through excited-state intramolecular proton transfer (ESIPT with the keto form and the enol form. After photocleavage, PHBT released a ratiometric fluorophore HBT, which showed dual emission bands with more than 73-fold fluorescence enhancement at 512 nm in buffer and more than 69-fold enhancement at 452 nm in bovine serum. The probe displayed a high ratiometric imaging resolution and is believed to have a wide application in biological imaging.

  16. Probing and controlling fluorescence blinking of single semiconductor nanoparticles

    Directory of Open Access Journals (Sweden)

    Hsien-Chen Ko

    2011-02-01

    Full Text Available In this review we present an overview of the experimental and theoretical development on fluorescence intermittency (blinking and the roles of electron transfer in semiconductor crystalline nanoparticles. Blinking is a very interesting phenomenon commonly observed in single molecule/particle experiments. Under continuous laser illumination, the fluorescence time trace of these single nanoparticles exhibit random light and dark periods. Since its first observation in the mid-1990s, this intriguing phenomenon has attracted wide attention among researchers from many disciplines. We will first present the historical background of the discovery and the observation of unusual inverse power-law dependence for the waiting time distributions of light and dark periods. Then, we will describe our theoretical modeling efforts to elucidate the causes for the power-law behavior, to probe the roles of electron transfer in blinking, and eventually to control blinking and to achieve complete suppression of the blinking, which is an annoying feature in many applications of quantum dots as light sources and fluorescence labels for biomedical imaging.

  17. Removal of Chromophore-proximal Polar Atoms Decreases Water Content and Increases Fluorescence in a Near Infrared Phytofluor

    Directory of Open Access Journals (Sweden)

    Heli eLehtivuori

    2015-11-01

    Full Text Available Genetically encoded fluorescent markers have revolutionized cell and molecular biology due to their biological compatibility, controllable spatiotemporal expression, and photostability. To achieve in vivo imaging in whole animals, longer excitation wavelength probes are needed due to the superior ability of near infrared light to penetrate tissues unimpeded by absorbance from biomolecules or autofluorescence of water. Derived from near infrared-absorbing bacteriophytochromes, phytofluors are engineered to fluoresce in this region of the electromagnetic spectrum, although high quantum yield remains an elusive goal. An invariant aspartate residue is of utmost importance for photoconversion in native phytochromes, presumably due to the proximity of its backbone carbonyl to the pyrrole ring nitrogens of the biliverdin (BV chromophore as well as the size and charge of the side chain. We hypothesized that the polar interaction network formed by the charged side chain may contribute to the decay of the excited state via proton transfer. Thus, we chose to further probe the role of this amino acid by removing all possibility for polar interactions with its carboxylate side chain by incorporating leucine instead. The resultant fluorescent protein, WiPhy2, maintains BV binding, monomeric status, and long maximum excitation wavelength while minimizing undesirable protoporphyrin IXα binding in cells. A crystal structure and time-resolved fluorescence spectroscopy reveal that water near the BV chromophore is excluded and thus validate our hypothesis that removal of polar interactions leads to enhanced fluorescence by increasing the lifetime of the excited state. This new phytofluor maintains its fluorescent properties over a broad pH range and does not suffer from photobleaching. WiPhy2 achieves the best compromise to date between high fluorescence quantum yield and long illumination wavelength in this class of fluorescent proteins.

  18. Analysis of Septin Reorganization at Cytokinesis Using Polarized Fluorescence Microscopy

    Directory of Open Access Journals (Sweden)

    Molly McQuilken

    2017-05-01

    Full Text Available Septins are conserved filament-forming proteins that act in diverse cellular processes. They closely associate with membranes and, in some systems, components of the cytoskeleton. It is not well understood how filaments assemble into higher-order structures in vivo or how they are remodeled throughout the cell cycle. In the budding yeast S. cerevisiae, septins are found through most of the cell cycle in an hourglass organization at the mother-bud neck until cytokinesis when the collar splits into two rings that disassemble prior to the next cell cycle. Experiments using polarized fluorescence microscopy have suggested that septins are arranged in ordered, paired filaments in the hourglass and undergo a coordinated 90° reorientation during splitting at cytokinesis. This apparent reorganization could be due to two orthogonal populations of filaments disassembling and reassembling or being preferentially retained at cytokinesis. In support of this idea, we report a decrease in septin concentration at the mother-bud neck during cytokinesis consistent with other reports and the timing of the decrease depends on known septin regulators including the Gin4 kinase. We took a candidate-based approach to examine what factors control reorientation during splitting and used polarized fluorescence microscopy to screen mutant yeast strains deficient in septin interacting proteins. Using this method, we have linked known septin regulators to different aspects of the assembly, stability, and reorganization of septin assemblies. The data support that ring splitting requires Gin4 activity and an anillin-like protein Bud4, and normal accumulation of septins at the ring requires phosphorylation of Shs1. We found distinct regulatory requirements for septin organization in the hourglass compared to split rings. We propose that septin subpopulations can vary in their localization and assembly/disassembly behavior in a cell-cycle dependent manner at cytokinesis.

  19. Polarization Characteristics Inferred From the Radio Receiver Instrument on the Enhanced Polar Outflow Probe

    Science.gov (United States)

    Danskin, Donald W.; Hussey, Glenn C.; Gillies, Robert G.; James, H. Gordon; Fairbairn, David T.; Yau, Andrew W.

    2018-02-01

    The Radio Receiver Instrument (RRI) on the CAScade, Smallsat, and Ionospheric Polar Explorer/enhanced Polar Outflow Probe (CASSIOPE/e-POP) satellite was used to receive continuous wave and binary phase shift keyed transmissions from a high-frequency transmitter located in Ottawa, ON, Canada during April 2016 to investigate how the ionosphere affects the polarization characteristics of transionospheric high-frequency radio waves. The spacecraft orientation was continuously slewed to maintain the dipole orientation in a plane perpendicular to the direction toward the transmitter, enabling the first in situ planar polarization determination for continuous wave and binary phase shift keyed modulated radio waves from space at times when the wave frequency is at least 1.58 times the plasma frequency. The Stokes parameters and polarization characteristics were derived from the measured data and interpreted using an existing ray tracing model. For the southern part of the passes, the power was observed to oscillate between the two dipoles of RRI, which was attributed to Faraday rotation of the radio waves. For the first time, a reversal in the rate of change of orientation angle was observed where the minimum in modeled Faraday rotation occurred. The reversal point was poleward of the point of closest approach between the satellite and transmitter; this was explained by the variations of total electron content and component of magnetic field along the direction of propagation. The received signals show both quasi-longitudinal (QL) and quasi-transverse characteristics. South of the transmitter the QL regime is dominant. Around the reversal point, a combination of QL and quasi-transverse nature was observed.

  20. Measuring reactive oxygen and nitrogen species with fluorescent probes: challenges and limitations

    Science.gov (United States)

    Kalyanaraman, Balaraman; Darley-Usmar, Victor; Davies, Kelvin J.A.; Dennery, Phyllis A.; Forman, Henry Jay; Grisham, Matthew B.; Mann, Giovanni E.; Moore, Kevin; Roberts, L. Jackson; Ischiropoulos, Harry

    2013-01-01

    The purpose of this position paper is to present a critical analysis of the challenges and limitations of the most widely used fluorescent probes for detecting and measuring reactive oxygen and nitrogen species. Where feasible, we have made recommendations for the use of alternate probes and appropriate analytical techniques that measure the specific products formed from the reactions between fluorescent probes and reactive oxygen and nitrogen species. We have proposed guidelines that will help present and future researchers with regard to the optimal use of selected fluorescent probes and interpretation of results. PMID:22027063

  1. A coumarin-quinolinium-based fluorescent probe for ratiometric sensing of sulfite in living cells.

    Science.gov (United States)

    Tan, Li; Lin, Weiying; Zhu, Sasa; Yuan, Lin; Zheng, Kaibo

    2014-07-14

    Based on a novel coumarin-quinolinium platform, probe 2 was rationally designed and synthesized as a novel ratiometric fluorescent sensor for sulfite anions. The probe exhibited a wide dynamic concentration range for sulfite anions in a PBS buffer (containing 1 mg mL(-1) BSA). More importantly, the probe was suitable for ratiometric fluorescence imaging in living cells with high sensitivity, favorable selectivity, and minimal cytotoxicity.

  2. A capillary-based probe for in situ detection of enhanced fluorescence signals

    Science.gov (United States)

    Long, F.; Xiao, R.; Zhu, A. N.; Shi, H. C.; Wang, S. Q.

    2013-07-01

    A simple, compact, and high sensitivity capillary-based probe for the in situ detection of fluorescence signals with high sensitivity is demonstrated. A home-made single-multi-mode fiber coupler that is coaxially aligned with the capillary-based probe provides for the transmission of excitation light and the collection and transmission of fluorescence. We propose a conceptually straightforward theoretical model to optimize the factors affecting the fluorescence-capture capability of the capillary-based probe. The fluorescence signal detected by fiber-optic spectroscopy non-linearly increases with the length of the capillary-based probe. In addition, the thicker the capillary tube wall is, the less the fluorescence signals determined are. The performance of the proposed probe is evaluated experimentally by measuring the fluorescence spectra of Cy5.5 dye and blue-green algae. The experimental results show that the proposed probe provides more than a ten-fold increase in fluorescence signal compared with direct measurements by a flat-tipped multi-mode fiber probe. The advantages of the capillary-based probe, which include its simple and compact structure, excellent light collection efficiency, requirement of small sample volume, and recoverability of samples, allow its wide application to in situ detection in the medical, forensic, biological, geological, and environmental fields with high sensitivity.

  3. Highly selective and rapidly responsive fluorescent probe for hydrogen sulfide detection in wine.

    Science.gov (United States)

    Wang, Hao; Wang, Jialin; Yang, Shaoxiang; Tian, Hongyu; Liu, Yongguo; Sun, Baoguo

    2018-08-15

    A new fluorescent probe 6-(2, 4-dinitrophenoxy)-2-naphthonitrile (probe 1) was designed and synthesized for the selective detection of hydrogen sulfide (H 2 S). The addition of H 2 S to a solution of probe 1 resulted in a marked fluorescence turn-on alongside a visual color change from colorless to light yellow. Importantly, this distinct color response indicated that probe 1 could be used as a visual sensor for H 2 S. Moreover, probe 1 was successfully used as a signal tool to determine the H 2 S levels in beer and red wine. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Inference of protein diffusion probed via fluorescence correlation spectroscopy

    Science.gov (United States)

    Tsekouras, Konstantinos

    2015-03-01

    Fluctuations are an inherent part of single molecule or few particle biophysical data sets. Traditionally, ``noise'' fluctuations have been viewed as a nuisance, to be eliminated or minimized. Here we look on how statistical inference methods - that take explicit advantage of fluctuations - have allowed us to draw an unexpected picture of single molecule diffusional dynamics. Our focus is on the diffusion of proteins probed using fluorescence correlation spectroscopy (FCS). First, we discuss how - in collaboration with the Bustamante and Marqusee labs at UC Berkeley - we determined using FCS data that individual enzymes are perturbed by self-generated catalytic heat (Riedel et al, Nature, 2014). Using the tools of inference, we found how distributions of enzyme diffusion coefficients shift in the presence of substrate revealing that enzymes performing highly exothermic reactions dissipate heat by transiently accelerating their center of mass following a catalytic reaction. Next, when molecules diffuse in the cell nucleus they often appear to diffuse anomalously. We analyze FCS data - in collaboration with Rich Day at the IU Med School - to propose a simple model for transcription factor binding-unbinding in the nucleus to show that it may give rise to apparent anomalous diffusion. Here inference methods extract entire binding affinity distributions for the diffusing transcription factors, allowing us to precisely characterize their interactions with different components of the nuclear environment. From this analysis, we draw key mechanistic insight that goes beyond what is possible by simply fitting data to ``anomalous diffusion'' models.

  5. A Fluorescent Probe for Sensitive Detection of Hydrazine and Its Application in Red Wine and Water.

    Science.gov (United States)

    Wang, Jialin; Wang, Hao; Yang, Shaoxiang; Tian, Hongyu; Liu, Yongguo; Hao, Yanfeng; Zhang, Jie; Sun, Baoguo

    2018-01-01

    A fluorescent probe, 7-(diethylamino)-2-oxo-2H-chromene-4-carbaldehyde (probe 1), was designed and synthesized for the sensitive detection of hydrazine. The addition of N 2 H 4 caused the fluorescence intensity of probe 1 to decrease. The probe's fluorescence was turn-off after adding N 2 H 4 , which could be observed under UV light at 365 nm. Moreover, once treated with different concentrations N 2 H 4 solutions, the solution color change could be distinguished, which indicates that probe 1 could be used as a visual sensor for hydrazine. Moreover, probe 1 can be used as a signal tool to determine hydrazine levels in solutions, such as red wine and water.

  6. Diagnosis of bovine brucellosis using a homogeneous fluorescence polarization assay.

    Science.gov (United States)

    Nielsen, K; Gall, D; Lin, M; Massangill, C; Samartino, L; Perez, B; Coats, M; Hennager, S; Dajer, A; Nicoletti, P; Thomas, F

    1998-12-11

    To evaluate the fluorescence polarization assay (FPA) for the serological diagnosis of bovine brucellosis, 118 sera from cattle which were culture positive for Brucella abortus, 1751 sera from cattle from premises containing cattle infected with B. abortus, 1222 sera from cattle vaccinated with B. abortus strain 19 and 1199 sera from cattle with no evidence of brucellosis were tested in Argentina, Chile, Mexico and in the American states of Iowa, Missouri and Texas. Initial determination of serological positivity and negativity was based upon reactivity in currently used serological tests, consisting of a rapid screening test, the rose-bengal or the buffered plate antigen tests, followed by a second serological test, the complement fixation test. Sensitivity of the FPA (sera from culture positive animals) ranged from 87.5% to 100%. Serological positivity of cattle from infected premises ranged from 65.5% to 99.0% while the % negative cattle in herds without evidence of brucellosis was between 94.9 and 100%. Of B. abortus strain 19 vaccinated cattle which were positive in at least one in-use serological tests, 88.2% were negative in the FPA. In contrast, previous Canadian studies, sensitivity values were 99.0% and 100% and the specificity in both cases was 100%. This discrepancy was probably due to the use of less well characterized sera in the current study.

  7. Benzoxazinone kanamycin A conjugate. A new fluorescent probe suitable to detect mycoplasmas in cell culture.

    Science.gov (United States)

    Monsigny, M; Midoux, P; Depierreux, C; Bebear, C; Le Bris, M T; Valeur, B

    1990-01-01

    The synthesis of a new benzoxazinone derivative suitable to detect early infection of cultured cells with mycoplasmas is described. p-[beta-(7-dimethylamino 1,4-benzoxazin 2-one 3yl)-vinyl]- phenylpropenoic acid was coupled to kanamycin A, an aminoglycoside leading to a cationic fluorescent probe which fluoresces at 600 nm upon excitation at 490 nm. This fluorescent probe is shown to heavily label the glycocallix of all the mycoplasma strains tested which are found to be associated with contaminated cultured cells and to allow an easy and rapid detection of contamination by fluorescence microscopy and flow cytometry.

  8. Application of locked nucleic acid-based probes in fluorescence in situ hybridization

    DEFF Research Database (Denmark)

    Fontenete, Sílvia; Carvalho, Daniel R; Guimarães, Nuno

    2016-01-01

    of nucleic acid mimics used as mixmers in LNA-based probes strongly influence the efficiency of detection. LNA probes with 10 to 15 mers showed the highest efficiency. Additionally, the combination of 2′-OMe RNA with LNA allowed an increase on the fluorescence intensities of the probes. Overall......Fluorescence in situ hybridization (FISH) employing nucleic acid mimics as probes is becoming an emerging molecular tool in the microbiology area for the detection and visualization of microorganisms. However, the impact that locked nucleic acid (LNA) and 2′-O-methyl (2′-OMe) RNA modifications have...

  9. In-vivo concentration ratio estimation of two fluorescent probes for early detection of Alzheimer's Disease

    Science.gov (United States)

    Harbater, Osnat; Gannot, Israel

    2015-03-01

    In-vivo measurement of the concentrations of biological compounds using fluorescence is one of the challenging biophotonic fields. These measurements are useful in diagnostic and treatment monitoring applications that use fluorescent probes which may bond to specific proteins and drugs. In some cases the relative concentration of two compounds is a sufficient biological indicator. For instance, it has been shown that the ratio between Amyloid-Beta and tau protein in the Cerebrospinal fluid (CSF) may predict the development of Alzheimer's disease (AD) several years before current diagnosis. We have previously suggested a system that could measure the concentration ratio of these two proteins in-vivo without the need to collect CSF samples. This system uses a miniature needle with an optical fiber which is coupled to a laser source and a detector. The fiber excites fluorescent probes which were injected and bond to the proteins in the CSF, and collects the fluorescence emission. Using the fluorescence intensity ratio, the concentration ratio between the proteins is estimated, and AD may be diagnosed. In this work we present the results of an in-vivo trial performed on mice. Miniature tubes containing two fluorescent probes in several concentration ratios were inserted into the mice in two locations: subcutaneously, and deeper in the abdomen. The fluorescent probes were excited and the fluorescence intensity was measured. The concentration ratios were extracted from the fluorescence intensities using a simple calibration curve. The extracted ratios are compared to the true ratios and the system's accuracy is estimated.

  10. Photophysical properties of a surfactive long-chain styryl merocyanine dye as fluorescent probe

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, L.F.M., E-mail: Lailafmi@yahoo.com [Al-Azhar University, Faculty of Science, Chemistry Department, Nasr City, 12 Ibrahim El-Nagar, El-Hegaz Sq. Heliopolis, Cairo 11315 (Egypt)

    2012-09-15

    This work deals with detailed investigations of the photophysical properties of a styryl merocyanine dye, namely 1-cetyl-4-[4 Prime -(methoxy) styryl]-pyridinium bromide (CMSPB) of molecular rotor type. The solvatochromic analyses of the data in different solvents using the Kamlet-Taft parameters ({alpha}, {beta}, {pi}{sup Low-Asterisk }) were discussed. Optical excitation of the studied merocyanine dye populates a CT S{sub 1} state with about 22.64 folds higher dipole moment value relative to that in the S{sub 0} state. Moreover, the effect of solvent viscosity (glycerol at various temperatures (299.0-351.0 K)) on CMSPB fluorescent properties is analyzed to understand the molecular mechanisms of the characteristic increase in CMSPB fluorescence intensity. The results indicate that CMSPB exhibits fluorescent properties typical for molecular rotors. The results show that torsional relaxation dynamics of molecular rotors in high-viscosity solvents cannot be described by the simple stick boundary hydrodynamics defined by the Debye-Stokes-Einstein (DSE) equation. The fluorescence depolarization behavior in glycerol at various temperatures (299.0-351.0 K) shows that the molecular rotational diffusion is controlled by the free volume of the medium. Furthermore, excited state studies in ethanol/chloroform mixture revealed the formation of weak complex with chloroform of stoichiometry 1:1 with formation constant of 0.004l mol{sup -1}. Moreover, the increase of the quantum yield values in micellar solutions of CTAB and SDS relative to that of water indicates that the guest dye molecules are microencapsulated into the hydrophobic interior of host micelle. The obtained non-zero values of fluorescence polarization in micellar solution imply reduced rotational depolarization of dye molecules via association with the surfactant. Upon comparing the spectral data in micelles with those in homogeneous solvent systems, more can be learned of the structural details of the micellar

  11. Rapidly Responsive and Highly Selective Fluorescent Probe for Bisulfite Detection in Food.

    Science.gov (United States)

    Wang, Jialin; Hao, Yanfeng; Wang, Hao; Yang, Shaoxiang; Tian, Hongyu; Sun, Baoguo; Liu, Yongguo

    2017-04-05

    The new fluorescent probe 4-hydroxy-3-((2E,4E)-5-phenylpenta-2,4-dienoyl)-2H-chromen-2-one (probe 1) was designed and synthesized for selective detection of sulfite. The fluorescence intensity of the probe was decreased only in the presence of HSO 3 - ; all other anions assessed resulted in an increased fluorescence response. Hence, probe 1 acts as a highly selective sensor for HSO 3 - . This sulfite sensitivity can also be readily monitored visually, as once treated with sulfite the solution shows a marked color change from yellow to colorless. Moreover, probe 1 can be conveniently used as a signal tool to determine the HSO 3 - levels in various sugar samples.

  12. Visualizing tributyltin (TBT) in bacterial aggregates by specific rhodamine-based fluorescent probes.

    Science.gov (United States)

    Jin, Xilang; Hao, Likai; She, Mengyao; Obst, Martin; Kappler, Andreas; Yin, Bing; Liu, Ping; Li, Jianli; Wang, Lanying; Shi, Zhen

    2015-01-01

    Here we present the first examples of fluorescent and colorimetric probes for microscopic TBT imaging. The fluorescent probes are highly selective and sensitive to TBT and have successfully been applied for imaging of TBT in bacterial Rhodobacter ferrooxidans sp. strain SW2 cell-EPS-mineral aggregates and in cell suspensions of the marine cyanobacterium Synechococcus PCC 7002 by using confocal laser scanning microscopy. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Optical imaging of non-fluorescent nanoparticle probes in live cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Gufeng; Stender, Anthony S.; Sun, Wei; and Fang, Ning

    2009-12-17

    Precise imaging of cellular and subcellular structures and dynamic processes in live cells is crucial for fundamental research in life sciences and in medical applications. Non-fluorescent nanoparticles are an important type of optical probe used in live-cell imaging due to their photostability, large optical cross-sections, and low toxicity. Here, we provide an overview of recent developments in the optical imaging of non-fluorescent nanoparticle probes in live cells.

  14. A new fluorescent pH probe for extremely acidic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Jiang, Zheng [School of Life Science, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Xiao, Yu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Bi, Fu-Zhen [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Miao, Jun-Ying, E-mail: miaojy@sdu.edu.cn [School of Life Science, Shandong University, Jinan 250100 (China); Zhao, Bao-Xiang, E-mail: bxzhao@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2014-04-01

    A new coumarin-based fluorescent probe can detect highly acidic conditions in both solution and bacteria with high selectivity and sensitivity. Highlights: • A new fluorescence probe for very low pH was synthesized and characterized. • The probe can monitor pH in solution and bacteria. • The two-step protonation of N atoms of the probe leads to fluorescence quenching. Abstract: A novel turn-off fluorescent probe based on coumarin and imidazole moiety for extremely acidic conditions was designed and developed. The probe with pKa = 2.1 is able to respond to very low pH value (below 3.5) with high sensitivity relying on fluorescence quenching at 460 nm in fluorescence spectra or the ratios of absorbance maximum at 380 nm to that at 450 nm in UV–vis spectra. It can quantitatively detect pH value based on equilibrium equation, pH = pKa -log[(Ix - Ib)/(Ia - Ix)]. It had very short response time that was less than 1 min, good reversibility and nearly no interference from common metal ions. Moreover, using ¹H NMR analysis and theoretical calculation of molecular orbital, we verified that a two-step protonation process of two N atoms of the probe leaded to photoinduced electron transfer (PET), which was actually the mechanism of the fluorescence quenching phenomenon under strongly acidic conditions. Furthermore, the probe was also applied to imaging strong acidity in bacteria, E.coli and had good effect. This work illustrates that the new probe could be a practical and ideal pH indicator for strongly acidic conditions with good biological significance.

  15. Unpolarized nucleon structure studies utilizing polarized electromagnetic probes

    International Nuclear Information System (INIS)

    Arrington, J.

    2009-01-01

    By the mid-1980s, measurements of the nucleon form factors had reached a stage where only slow, incremental progress was possible using unpolarized electron scattering. The development of high quality polarized beams, polarized targets, and recoil polarimeters led to a renaissance in the experimental program. I provide an overview of the changes in the field in the last ten years, which were driven by the dramatically improved data made possible by a new family of tools to measure polarization observables

  16. Molecularly imprinted fluorescent probe based on FRET for selective and sensitive detection of doxorubicin

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhifeng, E-mail: 897061147@qq.com [College of Chemistry and Materials Science, Hengyang Normal University, Key Laboratory of Functional Organometallic Materials of Hunan Province University, Hengyang 421008 (China); Deng, Peihong; Li, Junhua [College of Chemistry and Materials Science, Hengyang Normal University, Key Laboratory of Functional Organometallic Materials of Hunan Province University, Hengyang 421008 (China); Xu, Li [Department of Applied Chemistry, College of Materials and Energy, South China Agricultural University, Guangzhou 510642 (China); Tang, Siping [College of Chemistry and Materials Science, Hengyang Normal University, Key Laboratory of Functional Organometallic Materials of Hunan Province University, Hengyang 421008 (China)

    2017-04-15

    Highlights: • FRET-based molecularly imprinted probe for detection of doxorubicin was prepared. • The detection limit of the probe was 13.8 nM for doxorubicin. • The FRET-based probe had a higher selectivity for the template than ordinary MIMs. - Abstract: In this work, a new type of fluorescent probe for detection of doxorubicin has been constructed by the combined use of fluorescence resonance energy transfer (FRET) technology and molecular imprinting technique (MIT). Using doxorubicin as the template, the molecularly imprinted polymer thin layer was fabricated on the surfaces of carbon dot (CD) modified silica by sol-gel polymerization. The excitation energy of the fluorescent donor (CDs) could be transferred to the fluorescent acceptor (doxorubicin). The FRET based fluorescent probe demonstrated high sensitivity and selectivity for doxorubicin. The detection limit was 13.8 nM. The fluorescent probe was successfully applied for detecting doxorubicin in doxorubicin-spiked plasmas with a recovery of 96.8–103.8%, a relative standard deviation (RSD) of 1.3–2.8%. The strategy for construction of FRET-based molecularly imprinted materials developed in this work is very promising for analytical applications.

  17. Detection of coalescing agents in water-borne latex emulsions using an environment sensitive fluorescent probe

    NARCIS (Netherlands)

    Raja, T.N.; Brouwer, A.M.; Biemans, K.; Nabuurs, T.; Tennebroek, R.

    2010-01-01

    In this paper we report the determination of partitioning of coalescing agents (organic co-solvents) in water-borne latex emulsions by means of a fluorescence method. An environment-sensitive fluorescent probe 1 was copolymerized via emulsion polymerization. The presence of organic co-solvents

  18. A simple levulinate-based ratiometric fluorescent probe for sulfite with a large emission shift.

    Science.gov (United States)

    Liu, Caiyun; Wu, Huifang; Yang, Wen; Zhang, Xiaoling

    2014-01-01

    A simple 4-hydroxynaphthalimide-derived colorimetric and ratiometric fluorescent probe (1) containing a receptor of levulinate moiety was designed and synthesized to monitor sulfite. Probe 1 could quantificationally detect sulfite by a ratiometric fluorescence spectroscopy method with high selectivity and sensitivity. Specially, probe 1 exhibited a 100 nm red-shifted absorption spectrum along with the color changes from colorless to yellow, and 103 nm red-shifted emission spectra upon the addition of sulfite. Thus, 1 can serve as a "naked-eye" probe for sulfite. Further, the recognition mechanism of probe 1 for sulfite was confirmed using nuclear magnetic resonance and electrospray ionization mass spectrometry. Also, the preliminary practical application demonstrated that our proposed probe provided a promising method for the determination of sulfite.

  19. A fast-responsive fluorescent probe for sulfite and its bioimaging.

    Science.gov (United States)

    Wang, Jiaoliang; Long, Liping; Xiao, Xiaoming

    2016-05-01

    A turn-on fluorescent probe Coumarin-SO2 based on a nucleophilic addition reaction was developed for the rapid detection of SO3(2-) in aqueous media. The probe Coumarin-SO2 displays excellent water solubility, fast response, highly sensitivity and highly selectivity over other biological related species. More importantly, living cell imaging experiments indicate the feasibility of using the probe for the detection of SO3(2-) in biological systems. Copyright © 2015 John Wiley & Sons, Ltd.

  20. Polarization contrast in fluorescence scanning near-field optical microscopy in reflection

    NARCIS (Netherlands)

    Jalocha, A.; Jalocha, A.; van Hulst, N.F.

    1995-01-01

    Polarization contrast is presented in fluorescence images of a Langmuir-Blodgett monolayer obtained with a scanning near-field optical microscope operated in reflection. A tapered optical fiber is used both to excite and to collect the fluorescence. The lateral resolution in the reflection

  1. Ultrafast polarized fluorescence measurements on tryptophan and a tryptophan-containing peptide

    NARCIS (Netherlands)

    Larsen, O.F.A.; van Stokkum, I.H.M.; Pandit, A.; van Grondelle, R.; van Amerongen, H.

    2003-01-01

    In this work polarized picosecond fluorescence measurements were performed on isolated tryptophan and tryptophan in a small 22-mer peptide using a streak camera coupled to a spectrograph as a detection system. In both cases the fluorescence decay was multiexponential with decay times of ∼500 ps and

  2. Ultrafast polarized fluorescence measurements on Tryptophan and a Tryptophan-containing peptide

    NARCIS (Netherlands)

    Larsen, O.F.A.; Stokkum, van I.H.M.; Pandit, A.; Grondelle, van R.; Amerongen, van H.

    2003-01-01

    In this work polarized picosecond fluorescence measurements were performed on isolated tryptophan and tryptophan in a small 22-mer peptide using a streak camera coupled to a spectrograph as a detection system. In both cases the fluorescence decay was multiexponential with decay times of similar

  3. The influence of NBD fluorescent probe on model membranes containing POPC and DPPC.

    Science.gov (United States)

    Weng, Chi-Jung; Wu, Ju-Ping; Kuo, Ming-Yen; Hsueh, Ya-Wei

    2016-03-01

    To investigate the effect of fluorescent probe on the properties of membranes, we studied model membranes composed of 1,2- dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1-palmitoyl 2-oleoyl-sn-glycero-3-phosphocholine (POPC) in the presence and absence of fluorescent probe. The morphology of giant unilamellar vesicles (GUVs) has been observed as a function of temperature and composition by fluorescence microscopy using NBD-DOPE or C 6 -NBD-PC as the probe. The phase behavior of model membranes containing no fluorescent probe was investigated by 2 H-NMR spectroscopy. We found that the bright phase observed on GUVs was the fluid phase enriched in POPC and the dark phase was the gel phase enriched in DPPC. NBD-DOPE and C 6 -NBD-PC preferentially participated in the fluid-phase domains when GUVs were in the gel + fluid phase coexistence. Inclusion of both fluorescent probes (1 mol%) lowered the transition temperature of POPC/DPPC membranes. In addition, C 6 -NBD-PC exhibited a stronger effect than NBD-DOPE, which was considered to be associated with the structures of fluorescent molecules.

  4. Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species

    Science.gov (United States)

    Needham, Lisa-Maria; Weber, Judith; Fyfe, James W. B.; Kabia, Omaru M.; Do, Dung T.; Klimont, Ewa; Zhang, Yu; Rodrigues, Margarida; Dobson, Christopher M.; Ghandi, Sonia; Bohndiek, Sarah E.; Snaddon, Thomas N.; Lee, Steven F.

    2018-02-01

    Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H2O2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H2O2. We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H2O2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

  5. Newly synthesized carbocyanine fluorescent probes, their characteristics and behavior in proliferating cultures

    Directory of Open Access Journals (Sweden)

    Grischenko V. I.

    2009-12-01

    Full Text Available Aim. To study possibile application of C2, C9, C18 and JC-1 carbocyanine fluorescent dyes for cell culture characterization. Methods. Morphological methods, fluorescence-activated cell sorting (FACS analysis, luminescent microscopy were used. Results. The studied carbocyanine probes were shown to be preserved in dividing cells for at least 4 duplications. It was found that carbocyanine probe JC-1 did not transit from cell to cell under combined culturing of labeled and non-labeled cells. Conclusions. The paper covers the use of carbocyanine fluorescent probes for long-term culturing of cell lines. Probes C9 and JC-1 were optimal for the proliferative culture observation, allowing to trace mitochondrial functional state

  6. A simple and effective strategy to increase the sensitivity of fluorescence probes in living cells.

    Science.gov (United States)

    Izumi, Saki; Urano, Yasuteru; Hanaoka, Kenjiro; Terai, Takuya; Nagano, Tetsuo

    2009-07-29

    Noninvasive visualization and investigation of interactions among proteins, biomolecules, and enzymes in living cells is an important goal for biologists, and fluorescence probes are powerful tools for this purpose. Because many target molecules are present in only trace amounts, high sensitivity is very important, and it is common to improve the sensitivity of fluorescence probes by focusing on high reaction velocity, K(d). (Gee, K. R.; Archer, E. A.; Lapham, L. A.; Leonard, M. E.; Zhou, Z.; Bingham, J.; Diwu, Z. Bioorg. Med. Chem. Lett. 2000, 10, 1515-1518.) So far, we have designed and synthesized various highly sensitive fluorescence probes based on the above concepts. (Gabe, Y.; Urano, Y.; Kikuchi, K.; Kojima, H.; Nagano, T. J. Am. Chem. Soc. 2004, 126, 3357-3367. Komatsu, K.; Urano, Y.; Kojima, H.; Nagano, T. J. Am. Chem. Soc. 2007, 129, 13447-13454.) Nevertheless, they were sometimes insufficiently sensitive to detect biomolecules in living cells, despite high chemical sensitivity in cuvette. In this report, we suggest a new approach to increase the sensitivity of fluorescence probes, focusing on their intracellular retention. Since calcein is well-retained, we investigated its structural, chemical, and optical characteristics and found that the iminodiacetic acid group (IAG) is a key structure for the intracellular retention. We next designed and synthesized novel fluorescence probes containing IAGs. They showed superior intracellular retention, making it possible to visualize low concentrations of target molecules that would be difficult to observe with conventional probes and permitting long-term observation in living cells. Improvement of intracellular retention of fluorescence probes holds great promise as a strategy for developing a wide range of highly sensitive probes for studies on various biological phenomena.

  7. Interest of Fluorescence Derivatization and Fluorescence Probe Assisted Post-column Detection of Phospholipids: A Short Review

    Directory of Open Access Journals (Sweden)

    Pratrice Prognon

    2010-01-01

    Full Text Available Phospholipids are essential constituents of all living cell membranes. There are many analytical methods available for the quantitative and qualitative determination of phospholipids, but since these molecules lack chromophores, common absorbance based methods are of limited use. Beside mass spectrometry, some less specific approaches that are routinely used are evaporative light scattering detection or fluorescence, which exhibit sufficient sensitivity. Here, we focus on fluorescence, which remains an interesting way to quantify phospholipids. Two ways of detecting phospholipids by fluorescence are possible coupled with separation techniques such as thin layer chromatography (TLC, high performance liquid chromatography (HPLC and capillary electrophoresis (CE: firstly, pre-column derivatization procedures and secondly, probe assisted post-column detection with suitable fluorescence reagents. In both cases, the common purpose is to increase the detection sensitivity. It is shown that, whereas pre-column derivatization is characterized by selectivity due to the chemical functionality of the analyte involved in the derivatization process, in supramolecular post-column derivatization, the selectivity only proceeds from the capacity of the lipid to involve supramolecular assemblies with a fluorescence probe. The aim of this review is to summarize available experiments concerning fluorescence detection of phospholipids. The interest and limitation of such detection approaches are discussed.

  8. Fluorescence Probe Based on an Amino-Functionalized Fluorescent Magnetic Nanocomposite for Detection of Folic Acid in Serum.

    Science.gov (United States)

    Li, Xiaowan; Chen, Ligang

    2016-11-23

    A new fluorescence probe constructed with a multifunctional nanocomposite, Fe 3 O 4 -ZnS:Mn 2+ /SiO 2 -NH 2 , was successfully synthesized and then used to detect folic acid in real serum samples. The nanocomposite was characterized by fluorescence spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, and physical property measurement system. With the addition of analyte, the Fe 3 O 4 -ZnS:Mn 2+ /SiO 2 -NH 2 composite and folic acid formed a new complex because cross-linking of the amino and carboxyl groups participated in the condensation reaction. Then, the energy of quantum dots was transferred to the complex and led to quenching of the fluorescence. Moreover, the fluorescence intensity decreased significantly as the concentration of folic acid increased, and the fluorescence quenching ratio F 0 /F was related to the folic acid concentration in the range from 0.1 to 5 μg mL -1 . This method was used for detecting folic acid in real serum samples and gave recoveries in the range of 89.0%-96.0%, with relative standard deviations of 1.2%-3.9%. The detection limit was 9.6 ng mL -1 (S/N = 3). These satisfactory and simple results showed the great potential of this fluorescence probe in the field of pharmaceutical analysis.

  9. Determination of paraquat in water samples using a sensitive fluorescent probe titration method.

    Science.gov (United States)

    Yao, Feihu; Liu, Hailong; Wang, Guangquan; Du, Liming; Yin, Xiaofen; Fu, Yunlong

    2013-06-01

    Paraquat (PQ), a nonselective herbicide, is non-fluorescent in aqueous solutions. Thus, its determination through direct fluorescent methods is not feasible. The supramolecular inclusion interaction of PQ with cucurbit[7]uril was studied by a fluorescent probe titration method. Significant quenching of the fluorescence intensity of the cucurbit[7]uril-coptisine fluorescent probe was observed with the addition of PQ. A new fluorescent probe titration method with high selectivity and sensitivity at the ng/mL level was developed to determine PQ in aqueous solutions with good precision and accuracy based on the significant quenching of the supramolecular complex fluorescence intensity. The proposed method was successfully used in the determination of PQ in lake water, tap water, well water, and ditch water in an agricultural area, with recoveries of 96.73% to 105.77%. The fluorescence quenching values (deltaF) showed a good linear relationship with PQ concentrations from 1.0 x 10(-8) to 1.2 x 10(-5) mol/L with a detection limit of 3.35 x 10(-9) mol/L. In addition, the interaction models of the supramolecular complexes formed between the host and the guest were established using theoretical calculations. The interaction mechanism between the cucurbit[7]uril and PQ was confirmed by 1H NMR spectroscopy.

  10. Attomolar detection of proteins via cascade strand-displacement amplification and polystyrene nanoparticle enhancement in fluorescence polarization aptasensors.

    Science.gov (United States)

    Huang, Yong; Liu, Xiaoqian; Huang, Huakui; Qin, Jian; Zhang, Liangliang; Zhao, Shulin; Chen, Zhen-Feng; Liang, Hong

    2015-08-18

    Extremely sensitive and accurate measurements of protein markers for early detection and monitoring of diseases pose a formidable challenge. Herein, we develop a new type of amplified fluorescence polarization (FP) aptasensor based on allostery-triggered cascade strand-displacement amplification (CSDA) and polystyrene nanoparticle (PS NP) enhancement for ultrasensitive detection of proteins. The assay system consists of a fluorescent dye-labeled aptamer hairpin probe and a PS NP-modified DNA duplex (assistant DNA/trigger DNA duplex) probe with a single-stranded part and DNA polymerase. Two probes coexist stably in the absence of target, and the dye exhibits relatively low FP background. Upon recognition and binding with a target protein, the stem of the aptamer hairpin probe is opened, after which the opened hairpin probe hybridizes with the single-stranded part in the PS NP-modified DNA duplex probe and triggers the CSDA reaction through the polymerase-catalyzed recycling of both target protein and trigger DNA. Throughout this CSDA process, numerous massive dyes are assembled onto PS NPs, which results in a substantial FP increase that provides a readout signal for the amplified sensing process. Our newly proposed amplified FP aptasensor enables the quantitative measurement of proteins with the detection limit in attomolar range, which is about 6 orders of magnitude lower than that of traditional homogeneous aptasensors. Moreover, this sensing method also exhibits high specificity for target proteins and can be performed in homogeneous solutions. In addition, the suitability of this method for the quantification of target protein in biological samples has also been shown. Considering these distinct advantages, the proposed sensing method can be expected to provide an ultrasensitive platform for the analysis of various types of target molecules.

  11. Chlorophyll fluorescence extraction from water-leaving radiance of algae-containing water through polarization

    Science.gov (United States)

    Wang, Lin; Qiu, Zhongfeng; Pang, Huifang; Liu, Yongjian; Chen, Yanlong; Jiang, Lingling

    2017-12-01

    When measuring reflectance spectra, it is very important to accurately extract chlorophyll fluorescence from elastic- scattering light in water-leaving radiance. The elastic scattering of light by water particles produces partially polarized light. In contrast, chlorophyll fluorescence in planktonic algae yields completely unpolarized light. These properties can be used to separate fluorescent signals from the water-leaving radiance and thus to determine chlorophyll concentration. The algal species Aureococcus anophagefferens was used to conduct a laboratory polarization experiment. For the tests, we used a field spectroradiometer and a polarizer; measurements were collected using two different observation modes. The chlorophyll fluorescence curve extracted through polarization shows an excellent match with the results obtained using the fluorospectro photometer for both measurement modes, suggesting that polarization-based chlorophyll fluorescence extraction may be feasible. The extracted fluorescence is more reliable at incident zenith angles ranging from 30° to 60°. For algae-containing water, the results improve with increasing chlorophyll concentration. This method could help improve chlorophyll concentration measurement and the remote-sensing detection of resulting harmful algae blooms.

  12. An effective colorimetric and ratiometric fluorescent probe for bisulfite in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Xi [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Zhang, Tao [Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100 (China); Du, Zhi-Fang; Cao, Xiang-Jian; Chen, Ming-Yu [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Hu, Sheng-Wen [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Miao, Jun-Ying, E-mail: miaojy@sdu.edu.cn [Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100 (China); Zhao, Bao-Xiang, E-mail: bxzhao@sdu.edu.cn [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2015-08-12

    We have developed the first two-photon colorimetric and ratiometric fluorescent probe, BICO, for the detection of bisulfite (HSO{sub 3}{sup −}) in aqueous solution. The probe contains coumarin and benzimidazole moieties and can detect HSO{sub 3}{sup −} based on the Michael addition reaction with a limit of detection 5.3 × 10{sup −8} M in phosphate-buffered saline solution. The probe was used to detect bisulfite in tap water, sugar and dry white wine. Moreover, test strips were made and used easily. We successfully applied the probe to image living cells, using one-photon fluorescence imaging. BICO overcomes the limitations in sensitivity of previously reported probes and the solvation effect of bisulfite, which demonstrates its excellent value in practical application. - Highlights: • A colorimetric and ratiometric fluorescent probe was developed. • The probe could detect bisulfite in PBS buffer solution and real samples. • Bisulfite test paper was made to naked-eye detect bisulfite. • This probe successfully used to living cell imaging in ratiometric manner.

  13. An effective colorimetric and ratiometric fluorescent probe for bisulfite in aqueous solution

    International Nuclear Information System (INIS)

    Dai, Xi; Zhang, Tao; Du, Zhi-Fang; Cao, Xiang-Jian; Chen, Ming-Yu; Hu, Sheng-Wen; Miao, Jun-Ying; Zhao, Bao-Xiang

    2015-01-01

    We have developed the first two-photon colorimetric and ratiometric fluorescent probe, BICO, for the detection of bisulfite (HSO 3 − ) in aqueous solution. The probe contains coumarin and benzimidazole moieties and can detect HSO 3 − based on the Michael addition reaction with a limit of detection 5.3 × 10 −8  M in phosphate-buffered saline solution. The probe was used to detect bisulfite in tap water, sugar and dry white wine. Moreover, test strips were made and used easily. We successfully applied the probe to image living cells, using one-photon fluorescence imaging. BICO overcomes the limitations in sensitivity of previously reported probes and the solvation effect of bisulfite, which demonstrates its excellent value in practical application. - Highlights: • A colorimetric and ratiometric fluorescent probe was developed. • The probe could detect bisulfite in PBS buffer solution and real samples. • Bisulfite test paper was made to naked-eye detect bisulfite. • This probe successfully used to living cell imaging in ratiometric manner

  14. Fluorescence polarization of tetracycline derivatives as a technique for mapping nonmelanoma skin cancers.

    Science.gov (United States)

    Yaroslavsky, Anna N; Salomatina, Elena V; Neel, Victor; Anderson, Rox; Flotte, Thomas

    2007-01-01

    Nonmelanoma skin cancer is the most common form of human cancer, often resulting in high morbidity. Low visual contrast of these tumors makes their delineation a challenging problem. Employing a linearly polarized monochromatic light source and a wide-field CCD camera, we have developed a technique for fluorescence polarization imaging of the nonmelanoma cancers stained using antibiotics from the tetracycline family. To determine the feasibility of the method, fluorescence polarization images of 86 thick, fresh cancer excisions were studied. We found that the level of endogenous fluorescence polarization was much lower than that of exogenous, and that the average values of fluorescence polarization of tetracycline derivatives were significantly higher in cancerous as compared to normal tissue. Out of 86 tumors [54 stained in demeclocycline (DMN) and 32 in tetracycline (TCN)], in 79 cases (51-DMN, 28-TCN) the location, size, and shape of the lesions were identified accurately. The results of this trial indicate that nonmelanoma skin tumors can be distinguished from healthy tissue based on the differences in exogenous fluorescence polarization of TCN and/or DMN. Therefore, the developed technique can provide an important new tool for image-guided cancer surgery.

  15. Use of a Novel Rover-mounted Fluorescence Imager and Fluorescent Probes to Detect Biological Material in the Atacama Desert in Daylight

    Science.gov (United States)

    Weinstein, S.; Pane, D.; Warren-Rhodes, K.; Cockell, C.; Ernst, L. A.; Minkley, E.; Fisher, G.; Emani, S.; Wettergreen, D. S.; Wagner, M.

    2005-01-01

    We have developed an imaging system, the Fluorescence Imager (FI), for detecting fluorescence signals from sparse microorganisms and biofilms during autonomous rover exploration. The fluorescence signals arise both from naturally occurring chromophores, such as chlorophyll of cyanobacteria and lichens, and from fluorescent probes applied to soil and rocks. Daylight imaging has been accomplished by a novel use of a high-powered flashlamp synchronized to a CCD camera. The fluorescent probes are cell permanent stains that have extremely low intrinsic fluorescence (quantum yields less than 0.01) and a large fluorescence enhancement (quantum yields greater than 0.4) when bound to the target. Each probe specifically targets either carbohydrates, proteins, nucleic acids or membrane lipids, the four classes of macromolecules found in terrestrial life. The intent of the probes is to interrogate the environment for surface and endolithic life forms.

  16. Oral cancer detection based on fluorescence polarization of blood plasma at excitation wavelength 405 nm

    Science.gov (United States)

    Pachaiappan, Rekha; Prakasarao, Aruna; Manoharan, Yuvaraj; Dornadula, Koteeswaran; Singaravelu, Ganesan

    2017-02-01

    During metabolism the metabolites such as hormones, proteins and enzymes were released in to the blood stream by the cells. These metabolites reflect any change that occurs due to any disturbances in normal metabolic function of the human system. This was well observed with the altered spectral signatures observed with fluorescence spectroscopic technique. Previously many have reported on the significance of native fluorescence spectroscopic method in the diagnosis of cancer. As fluorescence spectroscopy is sensitive and simple, it has complementary techniques such as excitation-emission matrix, synchronous and polarization. The fluorescence polarization measurement provides details about any association or binding reactions and denaturing effects that occurs due to change in the micro environment of cells and tissues. In this study, we have made an attempt in the diagnosis of oral cancer at 405 nm excitation using fluorescence polarization measurement. The fluorescence anisotropic values calculated from polarized fluorescence spectral data of normal and oral cancer subjects yielded a good accuracy when analyzed with linear discriminant analysis based artificial neural network. The results will be discussed in detail.

  17. Polarization as a probe of high energy physics

    International Nuclear Information System (INIS)

    Moravcsik, M.J.

    1985-07-01

    An outline is given of the particular physical and mathematical point of view taken with respect to the exploration of polarization phenomena in particle physics, and some of the results are discussed. The quantum mechanical formalism is provided in terms of the reaction matrix and spin tensors. The applications of the optimal formalism to polarization phenomena and the results obtained from it are discussed. The four principal applications discussed are: testing of symmetry laws, determination of amplitudes from experimental data, testing of specific existing theoretical models, and searching for clues of dynamics in the situations in which knowledge of the particle dynamics is nonexistent or unreliable. 44 refs., 21 figs

  18. Synergistic Combination of Unquenching and Plasmonic Fluorescence Enhancement in Fluorogenic Nucleic Acid Hybridization Probes.

    Science.gov (United States)

    Vietz, Carolin; Lalkens, Birka; Acuna, Guillermo P; Tinnefeld, Philip

    2017-10-11

    Fluorogenic nucleic acid hybridization probes are widely used for detecting and quantifying nucleic acids. The achieved sensitivity strongly depends on the contrast between a quenched closed form and an unquenched opened form with liberated fluorescence. So far, this contrast was improved by improving the quenching efficiency of the closed form. In this study, we modularly combine these probes with optical antennas used for plasmonic fluorescence enhancement and study the effect of the nanophotonic structure on the fluorescence of the quenched and the opened form. As quenched fluorescent dyes are usually enhanced more by fluorescence enhancement, a detrimental reduction of the contrast between closed and opened form was anticipated. In contrast, we could achieve a surprising increase of the contrast with full additivity of quenching of the dark form and fluorescence enhancement of the bright form. Using single-molecule experiments, we demonstrate that the additivity of the two mechanisms depends on the perfect quenching in the quenched form, and we delineate the rules for new nucleic acid probes for enhanced contrast and absolute brightness. Fluorogenic hybridization probes optimized not only for quenching but also for the brightness of the open form might find application in nucleic acid assays with PCR avoiding detection schemes.

  19. Probing symmetry and symmetry breaking in resonant soft-x-ray fluorescence spectra of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Glans, P.; Gunnelin, K.; Guo, J. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Conventional non-resonant soft X-ray emission brings about information about electronic structure through its symmetry and polarization selectivity, the character of which is governed by simple dipole rules. For centro-symmetric molecules with the emitting atom at the inversion center these rules lead to selective emission through the required parity change. For the more common classes of molecules which have lower symmetry or for systems with degenerate core orbitals (delocalized over identical sites), it is merely the local symmetry selectivity that provides a probe of the local atomic orbital contribution to the molecular orbital. For instance, in X-ray spectra of first row species the intensities essentially map the p-density at each particular atomic site, and, in a molecular orbital picture, the contribution of the local p-type atomic orbitals in the LCAO description of the molecular orbitals. The situation is different for resonant X-ray fluorescence spectra. Here strict parity and symmetry selectivity gives rise to a strong frequency dependence for all molecules with an element of symmetry. In addition to symmetry selectivity the strong frequency dependence of resonant X-ray emission is caused by the interplay between the shape of a narrow X-ray excitation energy function and the lifetime and vibrational broadenings of the resonantly excited core states. This interplay leads to various observable effects, such as linear dispersion, resonance narrowing and emission line (Stokes) doubling. Also from the point of view of polarization selectivity, the resonantly excited X-ray spectra are much more informative than the corresponding non-resonant spectra. Examples are presented for nitrogen, oxygen, and carbon dioxide molecules.

  20. Multiplex fluorescence melting curve analysis for mutation detection with dual-labeled, self-quenched probes.

    Directory of Open Access Journals (Sweden)

    Qiuying Huang

    2011-04-01

    Full Text Available Probe-based fluorescence melting curve analysis (FMCA is a powerful tool for mutation detection based on melting temperature generated by thermal denaturation of the probe-target hybrid. Nevertheless, the color multiplexing, probe design, and cross-platform compatibility remain to be limited by using existing probe chemistries. We hereby explored two dual-labeled, self-quenched probes, TaqMan and shared-stem molecular beacons, in their ability to conduct FMCA. Both probes could be directly used for FMCA and readily integrated with closed-tube amplicon hybridization under asymmetric PCR conditions. Improved flexibility of FMCA by using these probes was illustrated in three representative applications of FMCA: mutation scanning, mutation identification and mutation genotyping, all of which achieved improved color-multiplexing with easy probe design and versatile probe combination and all were validated with a large number of real clinical samples. The universal cross-platform compatibility of these probes-based FMCA was also demonstrated by a 4-color mutation genotyping assay performed on five different real-time PCR instruments. The dual-labeled, self-quenched probes offered unprecedented combined advantage of enhanced multiplexing, improved flexibility in probe design, and expanded cross-platform compatibility, which would substantially improve FMCA in mutation detection of various applications.

  1. Fluorescent and quantitative mitochondrial redox imaging of tumor targeted by Octa-RGD probe

    Directory of Open Access Journals (Sweden)

    Shuang Sha

    2016-07-01

    Full Text Available Integrins, over-expressed in a broad range of cancer diseases, are widely utilized as a tumor biomarker. Metabolism investigation also plays important roles in tumor theranostics. Developing simple integrin-targetting probe and monitoring tumor metabolism will give opportunities to find ways for cancer treatment, however, the investigation of tumor metabolism with integrin receptor based probes has been rarely reported so far. Here, we developed an octavalent fluorescent probe Octa-RGD by convenient genetic method, based on one tetrameric far-red fluorescent protein (fRFP linked with RGD peptides. We validated its intergin targeting by confocal imaging in vitro. Then we screened a variety of tumor cells, and differentiated their binding affinity based on the fluorescence of the probe via flow cytometry. Among these cells, CNE-2 cells had the highest uptake of the probe, while B16 cells had the lowest, corresponding with their intergin expression levels. Next, the fluorescent and metabolic imaging was performed in HT1080 (intergin postive tumor, where nicotinamide adenine dinucleotide hydrogen (NADH, flavoprotein (Fp and fRFP fluorescent signals were collected. The tumor from mice intravenously injected with Octa-RGD probe displayed obviously higher NADH redox ratio NADH/(Fp+NADH and fRFP signal, than those with fRFP protein. It suggested that integrin targeting may have influence on the target cell metabolism, and further demonstrated Octa-RGD probe facilitated its uptake in the targeted tumor in vivo. This paper developed a useful probe, which can bind integrins specifically and efficiently in tumor cells, and together with tumor metabolic information, it may provide new insight for RGD targeting-based cancer therapeutics.

  2. Effect of PAF on polyrnorphonuclear leucocyte plasma membrane polarity: a fluorescence study

    Directory of Open Access Journals (Sweden)

    A. Kantar

    1993-01-01

    Full Text Available The effect of PAF on the plasma membrane polarity of polymorphonuclear leukocytes (PMNs was investigated by measuring the steady-state fluorescence emission spectra of 2-dimethylamino(6-1auroyl naphthalene (Laurdan, which is known to be incorporated at the hydrophobic-hydrophilic interface of the bilayer, displaying spectral sensitivity to the polarity of its surrounding. Laurdan shows a marked steady-state emission blue-shift in non-polar solvents, with respect to polar solvents. Our results demonstrate that PAF (10−7 M induces a blue shift of the fluorescence emission spectra of Laurdan. These changes are blocked in the presence of the PAF antagonist, L-659,989. Our data indicate that the interaction between PAF and PMNs is accompanied by a decrease in polarity in the hydrophobic-hydrophilic interface of the plasma membrane.

  3. Fluorescent Probes and Fluorescence (Microscopy Techniques — Illuminating Biological and Biomedical Research

    Directory of Open Access Journals (Sweden)

    Gregor P. C. Drummen

    2012-11-01

    Full Text Available Fluorescence, the absorption and re-emission of photons with longer wavelengths, is one of those amazing phenomena of Nature. Its discovery and utilization had, and still has, a major impact on biological and biomedical research, since it enables researchers not just to visualize normal physiological processes with high temporal and spatial resolution, to detect multiple signals concomitantly, to track single molecules in vivo, to replace radioactive assays when possible, but also to shed light on many pathobiological processes underpinning disease states, which would otherwise not be possible. Compounds that exhibit fluorescence are commonly called fluorochromes or fluorophores and one of these fluorescent molecules in particular has significantly enabled life science research to gain new insights in virtually all its sub-disciplines: Green Fluorescent Protein. Because fluorescent proteins are synthesized in vivo, integration of fluorescent detection methods into the biological system via genetic techniques now became feasible. Currently fluorescent proteins are available that virtually span the whole electromagnetic spectrum. Concomitantly, fluorescence imaging techniques were developed, and often progress in one field fueled innovation in the other. Impressively, the properties of fluorescence were utilized to develop new assays and imaging modalities, ranging from energy transfer to image molecular interactions to imaging beyond the diffraction limit with super-resolution microscopy. Here, an overview is provided of recent developments in both fluorescence imaging and fluorochrome engineering, which together constitute the “fluorescence toolbox” in life science research.

  4. THE MAGNETIC FIELD IN TAURUS PROBED BY INFRARED POLARIZATION

    International Nuclear Information System (INIS)

    Chapman, Nicholas L.; Goldsmith, Paul F.; Pineda, Jorge L.; Li Di; Clemens, D. P.; Krco, Marko

    2011-01-01

    We present maps of the plane-of-sky magnetic field within two regions of the Taurus molecular cloud: one in the dense core L1495/B213 filament and the other in a diffuse region to the west. The field is measured from the polarization of background starlight seen through the cloud. In total, we measured 287 high-quality near-infrared polarization vectors in these regions. In L1495/B213, the percent polarization increases with column density up to A V ∼ 9 mag, the limits of our data. The radiative torques model for grain alignment can explain this behavior, but models that invoke turbulence are inconsistent with the data. We also combine our data with published optical and near-infrared polarization measurements in Taurus. Using this large sample, we estimate the strength of the plane-of-sky component of the magnetic field in nine subregions. This estimation is done with two different techniques that use the observed dispersion in polarization angles. Our values range from 5 to 82 μG and tend to be higher in denser regions. In all subregions, the critical index of the mass-to-magnetic flux ratio is sub-unity, implying that Taurus is magnetically supported on large scales (∼2 pc). Within the region observed, the B213 filament takes a sharp turn to the north and the direction of the magnetic field also takes a sharp turn, switching from being perpendicular to the filament to becoming parallel. This behavior can be understood if we are observing the rim of a bubble. We argue that it has resulted from a supernova remnant associated with a recently discovered nearby gamma-ray pulsar.

  5. A Novel Method for Imaging Apoptosis Using a Caspase-1 Near-Infrared Fluorescent Probe

    Directory of Open Access Journals (Sweden)

    Shanta M. Messerli

    2004-03-01

    Full Text Available Here we describe a novel method for imaging apoptosis in cells using a near-infrared fluorescent (NIRF probe selective for caspase-1 (interleukin β-converting enzyme, ICE. This biocompatible, optically quenched ICE-NIRF probe incorporates a peptide substrate, which can be selectively cleaved by caspase-1, resulting in the release of fluorescence signal. The specificity of this probe for caspase-1 is supported by various lines of evidence: 1 activation by purified caspase-1, but not another caspase in vitro; 2 activation of the probe by infection of cells with a herpes simplex virus amplicon vector (HGC-ICE-IacZ expressing a catalytically active caspase-1-IacZ fusion protein; 3 inhibition of HGC-ICE-IacZ vector-induced activation of the probe by coincubation with the caspase-1 inhibitor YVAD-cmk, but not with a caspase-3 inhibitor; and 4 activation of the probe following standard methods of inducing apoptosis with staurosporine, ganciclovir, or ionizing radiation in culture. These results indicate that this novel ICE-NIRF probe can be used in monitoring endogenous and vector-expressed caspase-1 activity in cells. Furthermore, tumor implant experiments indicate that this ICE-NIRF probe can be used to detect caspase-1 activity in living animals. This novel ICE-NIRF probe should prove useful in monitoring endogenous and vector-expressed caspase-1 activity, and potentially apoptosis in cell culture and in vivo.

  6. The interaction of fluorescent nanodiamond probes with cellular media

    NARCIS (Netherlands)

    Hemelaar, Simon R; Nagl, Andreas; Bigot, François; Rodriquez Garcia, Melissa; de Vries, Marcel P; Chipaux, Mayeul; Schirhagl, Romana

    Fluorescent nanodiamonds (FNDs) are promising tools to image cells, bioanalytes and physical quantities such as temperature, pressure, and electric or magnetic fields with nanometer resolution. To exploit their potential for intracellular applications, the FNDs have to be brought into contact with

  7. LASER FLUORESCENCE EEM PROBE FOR CONE PENETROMETER POLLUTION ANALYSIS

    Science.gov (United States)

    A fiber optic LIF (Laser induced fluorescence) EEM (Excitation emission matrix) instrument for CPT deployment has been successfully developed and field tested. The system employs a Nd: YAG laser and Raman shifter as a rugged field portable excitation source. This excitation sou...

  8. Enzyme-Free Detection of Mutations in Cancer DNA Using Synthetic Oligonucleotide Probes and Fluorescence Microscopy

    DEFF Research Database (Denmark)

    Miotke, Laura; Maity, Arindam; Ji, Hanlee

    2015-01-01

    BACKGROUND: Rapid reliable diagnostics of DNA mutations are highly desirable in research and clinical assays. Current development in this field goes simultaneously in two directions: 1) high-throughput methods, and 2) portable assays. Non-enzymatic approaches are attractive for both types......) and finally, detection by fluorescence microscopy. The LNA containing probes display high binding affinity and specificity to DNA containing mutations, which allows for the detection of mutation abundance with an intercalating EvaGreen dye. We used a second probe, which increases the overall number of base...... pairs in order to produce a higher fluorescence signal by incorporating more dye molecules. Indeed we show here that using EvaGreen dye and LNA probes, genomic DNA containing BRAF V600E mutation could be detected by fluorescence microscopy at low femtomolar concentrations. Notably, this was at least...

  9. Direct probing of chromatography columns by laser-induced fluorescence. Technical progress report, September 1, 1989--February 28, 1993

    Energy Technology Data Exchange (ETDEWEB)

    McGuffin, V.L.

    1992-12-07

    This report summarizes the progress and accomplishments of this research project from September 1, 1989 to February 28, 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe insupercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

  10. Spectroscopic studies of DNA interactions with food colorant indigo carmine with the use of ethidium bromide as a fluorescence probe.

    Science.gov (United States)

    Ma, Yadi; Zhang, Guowen; Pan, Junhui

    2012-10-31

    The interaction of indigo carmine (IC) with calf thymus DNA in physiological buffer (pH 7.4), using ethidium bromide (EB) dye as a fluorescence probe, was investigated by ultraviolet-visible absorption, fluorescence, and circular dichroism (CD) spectroscopy, coupled with viscosity measurements and DNA-melting studies. Hypochromicity of the absorption spectra of IC and enhancement in fluorescence polarization of IC were observed with the addition of DNA. Moreover, the binding of IC to DNA was able to decrease iodide and single-stranded DNA (ssDNA) quenching effects, increase the melting temperature and relative viscosity of DNA, and induce the changes in CD spectra of DNA. All of the evidence indicated that IC interacted with DNA in the mode of intercalative binding. Furthermore, the three-way synchronous fluorescence spectra data obtained from the interaction between IC and DNA-EB were resolved by parallel factor analysis (PARAFAC), and the results provided simultaneously the concentration information and the pure spectra for the three reaction components (IC, EB, and DNA-EB) of the system at equilibrium. This PARAFAC demonstrated that the intercalation of IC molecules into DNA proceeded by substituting for EB in the DNA-EB complex. The calculated thermodynamic parameters, ΔH° and ΔS°, suggested that both hydrophobic interactions and hydrogen bonds played a predominant role in the binding of IC to DNA.

  11. A simple and sensitive fluorescent probe for specific detection of ...

    Indian Academy of Sciences (India)

    Yan-Fei Kang

    ety of human diseases like neurotoxicity, skin lesions, edema, muscle weakness, lethargy, slow growth, hair ... fore, the probe 1 could selectively detect Cys level. In order to explore the effects of other analytes for ... 1 for Cys did not change clearly in the presence of other amino acids or metal ions, even Hcy and GSH.

  12. A coumarin-based colorimetric fluorescent probe for hydrogen sulfide

    Indian Academy of Sciences (India)

    shift, good solubility and high quantum yield.10 Previ- ously, we reported a coumarin-based chromogenic and ratiometric probe for hydrazine.11 As we know, when the phenolic hydroxyl of a fluorophore is protected via esterification, no emission of the fluorophore would be found due to the electron-withdrawing property of.

  13. Carbon nanotube signal amplification for ultrasensitive fluorescence polarization detection of DNA methyltransferase activity and inhibition.

    Science.gov (United States)

    Huang, Yong; Shi, Ming; Zhao, Limin; Zhao, Shulin; Hu, Kun; Chen, Zheng-Feng; Chen, Jia; Liang, Hong

    2014-04-15

    A versatile sensing platform based on multiwalled carbon nanotube (MWCNT) signal amplification and fluorescence polarization (FP) is developed for the simple and ultrasensitive monitoring of DNA methyltransferase (MTase) activity and inhibition in homogeneous solution. This method uses a dye-labeled DNA probe that possess a doubled-stranded DNA (dsDNA) part for Mtase and its corresponding restriction endonuclease recognition, and a single-stranded DNA part for binding MWCNTs. In the absence of MTase, the dye-labeled DNA is cleaved by restriction endonuclease, and releases very short DNA carrying the dye that cannot bind to MWCNTs, which has relatively small FP value. However, in the presence of MTase, the specific recognition sequence in the dye-labeled DNA probe is methylated and not cleaved by restriction endonuclease. Thus, the dye-labeled methylated DNA product is adsorbed onto MWCNTs via strong π-π stacking interactions, which leads to a significant increase in the FP value due to the enlargement of the molecular volume of the dye-labeled methylated DNA/MWCNTs complex. This provides the basic of a quantitative measurement of MTase activity. By using the MWCNT signal amplification approach, the detection sensitivity can be significantly improved by two orders of magnitude over the previously reported methods. Moreover, this method also has high specificity and a wide dynamic range of over five orders of magnitude. Additionally, the suitability of this sensing platform for MTase inhibitor screening has also been demonstrated. This approach may serve as a general detection platform for sensitive assay of a variety of DNA MTases and screening potential drugs. © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  14. CdTe quantum dot as a fluorescence probe for vitamin B12 in dosage form

    Science.gov (United States)

    Vaishnavi, E.; Renganathan, R.

    2013-11-01

    We here report the CdTe quantum dot (CdTe QDs)-based sensor for probing vitamin B12 derivatives in aqueous solution. In this paper, simple and sensitive fluorescence quenching measurements has been employed. The Stern-Volmer constant (KSV), quenching rate constant (kq) and binding constant (K) were rationalized from fluorescence quenching measurement. Furthermore, the fluorescence resonance energy transfer (FRET) mechanism was discussed. This method was applicable over the concentration ranging from 1 to 14 μg/mL (VB12) with correlation coefficient of 0.993. The limit of detection (LOD) of VB12 was found to be 0.15 μg/mL. Moreover, the present approach opens a simple pathway for developing cost-effective, sensitive and selective QD-based fluorescence sensors/probes for biologically significant VB12 in pharmaceutical sample with mean recoveries in the range of 100-102.1%.

  15. Quantitatively Mapping Cellular Viscosity with Detailed Organelle Information via a Designed PET Fluorescent Probe

    Science.gov (United States)

    Liu, Tianyu; Liu, Xiaogang; Spring, David R.; Qian, Xuhong; Cui, Jingnan; Xu, Zhaochao

    2014-01-01

    Viscosity is a fundamental physical parameter that influences diffusion in biological processes. The distribution of intracellular viscosity is highly heterogeneous, and it is challenging to obtain a full map of cellular viscosity with detailed organelle information. In this work, we report 1 as the first fluorescent viscosity probe which is able to quantitatively map cellular viscosity with detailed organelle information based on the PET mechanism. This probe exhibited a significant ratiometric fluorescence intensity enhancement as solvent viscosity increases. The emission intensity increase was attributed to combined effects of the inhibition of PET due to restricted conformational access (favorable for FRET, but not for PET), and the decreased PET efficiency caused by viscosity-dependent twisted intramolecular charge transfer (TICT). A full map of subcellular viscosity was successfully constructed via fluorescent ratiometric detection and fluorescence lifetime imaging; it was found that lysosomal regions in a cell possess the highest viscosity, followed by mitochondrial regions. PMID:24957323

  16. Fluorescent Reporters and Biosensors for Probing the Dynamic Behavior of Protein Kinases

    Directory of Open Access Journals (Sweden)

    Juan A. González-Vera

    2015-11-01

    Full Text Available Probing the dynamic activities of protein kinases in real-time in living cells constitutes a major challenge that requires specific and sensitive tools tailored to meet the particular demands associated with cellular imaging. The development of genetically-encoded and synthetic fluorescent biosensors has provided means of monitoring protein kinase activities in a non-invasive fashion in their native cellular environment with high spatial and temporal resolution. Here, we review existing technologies to probe different dynamic features of protein kinases and discuss limitations where new developments are required to implement more performant tools, in particular with respect to infrared and near-infrared fluorescent probes and strategies which enable improved signal-to-noise ratio and controlled activation of probes.

  17. Measurement of Quarkonium polarization to probe QCD at the LHC

    International Nuclear Information System (INIS)

    Knünz, V.

    2015-01-01

    With the first proton-proton collisions in the Large Hadron Collider (LHC) at CERN in 2010, a new era in high energy physics has been initiated. The data collected by the various experiments open up the possibility to study standard model processes with high precision, in new areas of phase space. The LHC provides excellent conditions for studies of quarkonium production, due to the high quarkonium production rates given the high center-of-mass energy and high instantaneous luminosity of the colliding proton beams. Studies of the production of heavy quarkonium mesons - bound states of a heavy quark and its respective antiquark - are very important to improve our understanding of hadron formation. Until quite recently, experimental and phenomenological efforts have not resulted in a satisfactory overall picture of quarkonium production cross sections and quarkonium polarizations. The Compact Muon Solenoid (CMS) detector is ideally suited to study quarkonium production in the experimentally very clean dimuon decay channel, up to considerably higher values of transverse momentum than accessible in previous experiments. The scope of this thesis is to describe in detail the measurements of the polarizations of the Upsilon(nS) bottomonium states and (in less detail) of the Psi(nS) charmonium states, based on a dimuon data sample collected with the CMS detector in proton-proton collisions at a center-of-mass energy of 7 TeV. Surprisingly, no significant polarizations were found in any of the studied quarkonium states, in none of the studied reference frames, nor in a frame-independent analysis. From an experimental point of view, these results, together with recent results from other experiments, clarify the confusing picture originating from previous measurements, which were plagued by experimental ambiguities and inconsistencies. The currently most favored approach to model and understand quarkonium production is non-relativistic quantum chromodynamics (NRQCD), a QCD

  18. A coumarin-based fluorescent probe as a central nervous system disease biomarker.

    Science.gov (United States)

    Yap, Ann-Chee; Mahamad, Ummi Affah; Lim, Shen-Yang; Kim, Hae-Jo; Choo, Yeun-Mun

    2014-11-10

    Homocysteine and methylmalonic acid are important biomarkers for diseases associated with an impaired central nervous system (CNS). A new chemoassay utilizing coumarin-based fluorescent probe 1 to detect the levels of homocysteine is successfully implemented using Parkinson's disease (PD) patients' blood serum. In addition, a rapid identification of homocysteine and methylmalonic acid levels in blood serum of PD patients was also performed using the liquid chromatography-mass spectrometry (LC-MS). The results obtained from both analyses were in agreement. The new chemoassay utilizing coumarin-based fluorescent probe 1 offers a cost- and time-effective method to identify the biomarkers in CNS patients.

  19. A Coumarin-Based Fluorescent Probe as a Central Nervous System Disease Biomarker

    Directory of Open Access Journals (Sweden)

    Ann-Chee Yap

    2014-11-01

    Full Text Available Homocysteine and methylmalonic acid are important biomarkers for diseases associated with an impaired central nervous system (CNS. A new chemoassay utilizing coumarin-based fluorescent probe 1 to detect the levels of homocysteine is successfully implemented using Parkinson’s disease (PD patients’ blood serum. In addition, a rapid identification of homocysteine and methylmalonic acid levels in blood serum of PD patients was also performed using the liquid chromatography-mass spectrometry (LC-MS. The results obtained from both analyses were in agreement. The new chemoassay utilizing coumarin-based fluorescent probe 1 offers a cost- and time-effective method to identify the biomarkers in CNS patients.

  20. Gd(iii)-doped carbon dots as a dual fluorescent-MRI probe

    KAUST Repository

    Bourlinos, Athanasios B.

    2012-01-01

    We describe the synthesis of Gd(iii)-doped carbon dots as dual fluorescence-MRI probes for biomedical applications. The derived Gd(iii)-doped carbon dots show uniform particle size (3-4 nm) and gadolinium distribution and form stable dispersions in water. More importantly, they exhibit bright fluorescence, strong T1-weighted MRI contrast and low cytotoxicity. © The Royal Society of Chemistry 2012.

  1. Fluorescence emission and polarization analyses for evaluating binding of ruthenium metalloglycocluster to lectin and tetanus toxin c-fragment

    Science.gov (United States)

    Okada, Tomoko; Minoura, Norihiko

    2010-02-01

    We have developed a fluorescent ruthenium metalloglycocluster as a powerful molecular probe for evaluating a binding event between carbohydrates and lectins by fluorescence emission (FE) and fluorescence polarization (FP) analysis. The fluorescent ruthenium metalloglycoclusters, [Ru(bpy-2Gal)3] and [Ru(bpy-2Glc)3], possess clustered galactose and glucose surrounding the ruthenium center. Changes in FE and FP of these metalloglycoclusters were measured by adding each lectin (Peanut agglutinin (PNA), Ricinus communis agglutinin 120 (RCA), Concanavalin A (ConA), or Wheat germ agglutinin (WGA)) or tetanus toxin c-fragment (TCF). Following the addition of PNA, the FE spectrum of [Ru(bpy- 2Gal)3] showed new emission peak and the FP value of [Ru(bpy-2Gal)3] increased. Similarly, the FE spectrum of [Ru(bpy-2Glc)3] showed new emission peak and the FP value increased following the addition of ConA. Since other combinations of the metalloglycoclusters and lectin caused little change, specific bindings of galactose to PNA and glucose to ConA were proved by the FE and FP measurement. From nonlinear least-squares fitting, dissociation constants (Kd) of [Ru(bpy-2Gal)3] to PNA was 6.1 μM, while the Kd values of [Ru(bpy)2(bpy-2Gal)] to PNA was ca. 10-4 M. Therefore, the clustered carbohydrates were proved to increase affinity to lectins. Furthermore, the FP measurements proved specific binding of [Ru(bpy-2Gal)3] to TCF.

  2. A Cu(II)-benzoyl hydrazone based fluorescent probe for lipopolysaccharides

    International Nuclear Information System (INIS)

    Yang, Jing; Huang, Lei; Guo, Zhengyu; Ren, Wang; Wang, Qiusheng

    2016-01-01

    A novel fluorescent compound 7-diethylamino-3-[4'-N-((2-ethoxy)ethanol)methyl aminobenzoylhydrazone]methyl coumarin (I) was synthesized and employed as a fluorescent probe for detecting lipopolysaccharides (LPS). This coumarin-based probe exhibited high fluorescence in aqueous environment, which could be quenched in the presence of Cu 2+ ion due to the complexation between I and Cu 2+ . However, the fluorescence of I can be recovered upon addition of LPS, because the binding between LPS and Cu 2+ ion is stronger than that between I and Cu 2+ ion, which disassociates the complexation of I and Cu 2+ ion and releases the fluorescence of I. Therefore, this three-component sensing system can be used to detect lipopolysaccharides in a facile manner. In addition, biological imaging studies have demonstrated that the probe can be used to evaluate the biosorptive capacity for Cu 2+ ion in living bacteria. - Highlights: • A novel water-soluble coumarin derivative was synthesized. • Compound I was used to detect lipopolysaccharides selectively. • The detection process was studied upon UV–vis and fluorescence spectrum. • The bioimaging application of I in bacteria was studied.

  3. Detection of reactive oxygen species in mainstream cigarette smoke by a fluorescent probe

    Science.gov (United States)

    Liu, Li; Xu, Shi-jie; Li, Song-zhan

    2009-07-01

    A mass of reactive oxygen species(ROS) are produced in the process of smoking. Superfluous ROS can induce the oxidative stress in organism, which will cause irreversible damage to cells. Fluorescent probe is taken as a marker of oxidative stress in biology and has been applied to ROS detection in the field of biology and chemistry for high sensitivity, high simplicity of data collection and high resolution. As one type of fluorescent probe, dihydrorhodamine 6G (dR6G) will be oxidized to the fluorescent rhodamine 6G, which could be used to detect ROS in mainstream cigarette smoke. We investigated the action mechanism of ROS on dR6G, built up the standard curve of R6G fluorescence intensity with its content, achieved the variation pattern of R6G fluorescence intensity with ROS content in mainstream cigarette smoke and detected the contents of ROS from the 4 types of cigarettes purchased in market. The result shows that the amount of ROS has close relationship with the types of tobacco and cigarette production technology. Compared with other detecting methods such as electronic spin resonance(ESR), chromatography and mass spectrometry, this detection method by the fluorescent probe has higher efficiency and sensitivity and will have wide applications in the ROS detection field.

  4. The fast polarization modulation based dualfocus fluorescence correlation spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Štefl, Martin; Benda, Aleš; Gregor, I.; Hof, Martin

    2014-01-01

    Roč. 22, č. 1 (2014), s. 885-899 ISSN 1094-4087 R&D Projects: GA AV ČR KJB400400904; GA ČR GBP208/12/G016 Institutional support: RVO:61388955 Keywords : spectroscopy * fluorescence and luminiscence * confocal microscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.488, year: 2014

  5. An excited-state intramolecular photon transfer fluorescence probe for localizable live cell imaging of cysteine

    Science.gov (United States)

    Liu, Wei; Chen, Wen; Liu, Si-Jia; Jiang, Jian-Hui

    2017-03-01

    Small molecule probes suitable for selective and specific fluorescence imaging of some important but low-concentration intracellular reactive sulfur species such as cysteine (Cys) pose a challenge in chemical biology. We present a readily available, fast-response fluorescence probe CHCQ-Ac, with 2-(5‧-chloro-2-hydroxyl-phenyl)-6-chloro-4(3 H)-quinazolinone (CHCQ) as the fluorophore and acrylate group as the functional moiety, that enables high-selectivity and high-sensitivity for detecting Cys in both solution and biological system. After specifically reacted with Cys, the probe undergoes a seven-membered intramolecular cyclization and released the fluorophore CHCQ with excited-state intramolecular photon transfer effect. A highly fluorescent, insoluble aggregate was then formed to facilitate high-sensitivity and high-resolution imaging. The results showed that probe CHCQ-Ac affords a remarkably large Stokes shift and can detect Cys under physiological pH condition with no interference from other analytes. Moreover, this probe was proved to have excellent chemical stability, low cytotoxicity and good cell permeability. Our design of this probe provides a novel potential tool to visualize and localize cysteine in bioimaging of live cells that would greatly help to explore various Cys-related physiological and pathological cellular processes in cell biology and diagnostics.

  6. Photoemission of Bi_{2}Se_{3} with Circularly Polarized Light: Probe of Spin Polarization or Means for Spin Manipulation?

    Directory of Open Access Journals (Sweden)

    J. Sánchez-Barriga

    2014-03-01

    Full Text Available Topological insulators are characterized by Dirac-cone surface states with electron spins locked perpendicular to their linear momenta. Recent theoretical and experimental work implied that this specific spin texture should enable control of photoelectron spins by circularly polarized light. However, these reports questioned the so far accepted interpretation of spin-resolved photoelectron spectroscopy. We solve this puzzle and show that vacuum ultraviolet photons (50–70 eV with linear or circular polarization indeed probe the initial-state spin texture of Bi_{2}Se_{3} while circularly polarized 6-eV low-energy photons flip the electron spins out of plane and reverse their spin polarization, with its sign determined by the light helicity. Our photoemission calculations, taking into account the interplay between the varying probing depth, dipole-selection rules, and spin-dependent scattering effects involving initial and final states, explain these findings and reveal proper conditions for light-induced spin manipulation. Our results pave the way for future applications of topological insulators in optospintronic devices.

  7. Terbium fluorescence as a sensitive, inexpensive probe for UV-induced damage in nucleic acids

    International Nuclear Information System (INIS)

    El-Yazbi, Amira F.; Loppnow, Glen R.

    2013-01-01

    Graphical abstract: -- Highlights: •Simple, inexpensive, mix-and-read assay for positive detection of DNA damage. •Recognition of undamaged DNA via hybridization to a hairpin probe. •Terbium(III) fluorescence reports the amount of damage by binding to ssDNA. •Tb/hairpin is a highly selective and sensitive fluorescent probe for DNA damage. -- Abstract: Much effort has been focused on developing methods for detecting damaged nucleic acids. However, almost all of the proposed methods consist of multi-step procedures, are limited, require expensive instruments, or suffer from a high level of interferences. In this paper, we present a novel simple, inexpensive, mix-and-read assay that is generally applicable to nucleic acid damage and uses the enhanced luminescence due to energy transfer from nucleic acids to terbium(III) (Tb 3+ ). Single-stranded oligonucleotides greatly enhance the Tb 3+ emission, but duplex DNA does not. With the use of a DNA hairpin probe complementary to the oligonucleotide of interest, the Tb 3+ /hairpin probe is applied to detect ultraviolet (UV)-induced DNA damage. The hairpin probe hybridizes only with the undamaged DNA. However, the damaged DNA remains single-stranded and enhances the intrinsic fluorescence of Tb 3+ , producing a detectable signal directly proportional to the amount of DNA damage. This allows the Tb 3+ /hairpin probe to be used for sensitive quantification of UV-induced DNA damage. The Tb 3+ /hairpin probe showed superior selectivity to DNA damage compared to conventional molecular beacons probes (MBs) and its sensitivity is more than 2.5 times higher than MBs with a limit of detection of 4.36 ± 1.2 nM. In addition, this probe is easier to synthesize and more than eight times cheaper than MBs, which makes its use recommended for high-throughput, quantitative analysis of DNA damage

  8. Study of polarization properties of fiber-optics probes with use of a binary phase plate.

    Science.gov (United States)

    Alferov, S V; Khonina, S N; Karpeev, S V

    2014-04-01

    We conduct a theoretical and experimental study of the distribution of the electric field components in the sharp focal domain when rotating a zone plate with a π-phase jump placed in the focused beam. Comparing the theoretical and experimental results for several kinds of near-field probes, an analysis of the polarization sensitivity of different types of metal-coated aperture probes is conducted. It is demonstrated that with increasing diameter of the non-metal-coated tip part there occurs an essential redistribution of sensitivity in favor of the transverse electric field components and an increase of the probe's energy throughput.

  9. "Turn-on" fluorescent probe for detection of H2S and its applications in bioimaging

    Science.gov (United States)

    Zhao, Qi; Kang, Jin; Wen, Ying; Huo, Fangjun; Zhang, Yongbin; Yin, Caixia

    2018-01-01

    A novel fluorescent probe (named YQ-1) containing disulfide-bond coumarin derivative was developed for H2S. In response to H2S, YQ-1 showed remarkable fluorescent emission enhancement at 462 nm. Besides, YQ-1 exhibited higher selectivity, faster response rate, low cytotoxicity and low detection limit (0.052 μM). Further, YQ-1 was used to detect the presence of H2S level in living A549 cells, indicating YQ-1 has good membrane permeability and fluorescence properties.

  10. Fluorescent Bisphosphonate and Carboxyphosphonate Probes: A Versatile Imaging Toolkit for Applications in Bone Biology and Biomedicine.

    Science.gov (United States)

    Sun, Shuting; Błażewska, Katarzyna M; Kadina, Anastasia P; Kashemirov, Boris A; Duan, Xuchen; Triffitt, James T; Dunford, James E; Russell, R Graham G; Ebetino, Frank H; Roelofs, Anke J; Coxon, Fraser P; Lundy, Mark W; McKenna, Charles E

    2016-02-17

    A bone imaging toolkit of 21 fluorescent probes with variable spectroscopic properties, bone mineral binding affinities, and antiprenylation activities has been created, including a novel linking strategy. The linking chemistry allows attachment of a diverse selection of dyes fluorescent in the visible to near-infrared range to any of the three clinically important heterocyclic bisphosphonate bone drugs (risedronate, zoledronate, and minodronate or their analogues). The resultant suite of conjugates offers multiple options to "mix and match" parent drug structure, fluorescence emission wavelength, relative bone affinity, and presence or absence of antiprenylation activity, for bone-related imaging applications.

  11. Dual-Color Fluorescence Imaging of Magnetic Nanoparticles in Live Cancer Cells Using Conjugated Polymer Probes

    Science.gov (United States)

    Sun, Minjie; Sun, Bin; Liu, Yun; Shen, Qun-Dong; Jiang, Shaojun

    2016-01-01

    Rapid growth in biological applications of nanomaterials brings about pressing needs for exploring nanomaterial-cell interactions. Cationic blue-emissive and anionic green-emissive conjugated polymers are applied as dual-color fluorescence probes to the surface of negatively charged magnetic nanoparticles through sequentially electrostatic adsorption. These conjugated polymers have large extinction coefficients and high fluorescence quantum yield (82% for PFN and 62% for ThPFS). Thereby, one can visualize trace amount (2.7 μg/mL) of fluorescence-labeled nanoparticles within cancer cells by confocal laser scanning microscopy. Fluorescence labeling by the conjugated polymers is also validated for quantitative determination of the internalized nanoparticles in each individual cell by flow cytometry analysis. Extensive overlap of blue and green fluorescence signals in the cytoplasm indicates that both conjugated polymer probes tightly bind to the surface of the nanoparticles during cellular internalization. The highly charged and fluorescence-labeled nanoparticles non-specifically bind to the cell membranes, followed by cellular uptake through endocytosis. The nanoparticles form aggregates inside endosomes, which yields a punctuated staining pattern. Cellular internalization of the nanoparticles is dependent on the dosage and time. Uptake efficiency can be enhanced three-fold by application of an external magnetic field. The nanoparticles are low cytotoxicity and suitable for simultaneously noninvasive fluorescence and magnetic resonance imaging application. PMID:26931282

  12. Nitroreductase-triggered activation of a novel caged fluorescent probe obtained from methylene blue.

    Science.gov (United States)

    Bae, Jungeun; McNamara, Louis E; Nael, Manal A; Mahdi, Fakhri; Doerksen, Robert J; Bidwell, Gene L; Hammer, Nathan I; Jo, Seongbong

    2015-08-18

    A near-infrared fluorescent probe based on methylene blue (p-NBMB) was developed for the detection of nitroreductase. Conjugating methylene blue with a p-nitrobenzyl moiety enables it to be activated by nitroreductase-catalyzed 1,6-elimination, resulting in the release of an active methylene blue fluorophore.

  13. Dipodal quinoline-tethered fluorescent probe synthesis and investigation of spectroscopic properties

    Science.gov (United States)

    Obalı, Aslıhan Yılmaz; Yilmaz, Menzeher Serkan; Uçan, Halil İsmet

    2017-10-01

    Novel quinoline-tethered fluorescent probe was designed and synthesized as multidentate ligand. Their sensing actions were confirmed by UV-Vis absorbance and emission spectroscopic studies in presence of perchlorate salts of Co2+, Li+, Fe2+, K+, Pb2+, Cu2+, Zn2+, Ni2+, Hg2+, Ag+ cations in acetonitrile (1 × 10-5 M for absorption studies, 1 × 10-7 M for fluorescence studies). It was found that the dipodal compounds can selectively bind to Cu2+ and Ag+ metal ions with a significant quenching in their emissions. The capture of Cu2+ and Ag+ by the probe resulted in deprotonation of the secondary amine conjugated to the quinoline-tethered probe, so that the electron-donation ability of the 'N' atom would be greatly enhanced and the probe (2) showed blue-shift in emission and exhibited an on-off fluorescent response. The binding study was explored by using fluorescence spectroscopy with Job plot method.

  14. Genetically Encoded Fluorescent Probe for Imaging Apoptosis in Vivo with Spontaneous GFP Complementation.

    Science.gov (United States)

    Nasu, Yusuke; Asaoka, Yoichi; Namae, Misako; Nishina, Hiroshi; Yoshimura, Hideaki; Ozawa, Takeaki

    2016-01-05

    Apoptosis plays a pivotal role in development and tissue homeostasis in multicellular organisms. Dysfunction of apoptosis is involved in many fatal diseases such as cancer. Visualization of apoptosis in living animals is necessary to understand the mechanism of apoptosis-related diseases. Here, we describe a genetically encoded fluorescent probe for imaging apoptosis in living multicellular organisms, based on spontaneous complementation of two fragments of a green fluorescent protein (GFP) variant (GFP OPT). The probe is designed for detection of mitochondria-mediated apoptosis during which a mitochondrial protein of Smac is released into cytosol. The Smac is connected with a carboxy-terminal fragment of GFP OPT (GFP11), whereas the remainder of GFP OPT (GFP(1-10)) is located in the cytosol. Under an apoptotic condition, the Smac is released from mitochondria into cytosol, allowing complementation of the GFP-OPT fragments and the emission of fluorescence. Live-cell imaging demonstrates that the probe enables detection of apoptosis in living cells with a high signal-to-background ratio. We applied the probe to living zebrafish, in which apoptotic cells were visualized with fluorescence. The technique provides a useful tool for the study of apoptosis in living animals, facilitating elucidation of the mechanisms of apoptosis-related diseases.

  15. Probing of cosolvents in polymer latex materials by using solvatochromic fluorescence

    NARCIS (Netherlands)

    Brouwer, A.M.; Raja, T.N.; Biemans, K.; Nabuurs, T.; Tennebroek, R.

    2008-01-01

    The process of film formation is of great importance for the application of organic coatings. In waterborne coatings, organic cosolvents are still indispensable, but regulations force the industry to reduce their amounts. Here we describe a method that uses the solvatochromic fluorescence of a probe

  16. Symmetric cyanovinyl-pyridinium triphenylamine: a novel fluorescent switch-on probe for an antiparallel G-quadruplex.

    Science.gov (United States)

    Lai, Han; Lai, Hai; Xiao, Yijie; Yan, Shengyong; Tian, Fangfang; Zhong, Cheng; Liu, Yi; Weng, Xiaocheng; Zhou, Xiang

    2014-04-21

    In this study, we present a fluorescent switch-on probe based on a cyanovinyl-pyridinium triphenylamine (CPT) derivative that exhibited a 190-fold increase in fluorescence upon binding to G-quadruplex-forming oligonucleotide 22AG. This probe showed specificity and selectivity towards an antiparallel G-quadruplex, indicating its promising potential in G-quadruplex imaging.

  17. Mass amplifying probe for sensitive fluorescence anisotropy detection of small molecules in complex biological samples.

    Science.gov (United States)

    Cui, Liang; Zou, Yuan; Lin, Ninghang; Zhu, Zhi; Jenkins, Gareth; Yang, Chaoyong James

    2012-07-03

    Fluorescence anisotropy (FA) is a reliable and excellent choice for fluorescence sensing. One of the key factors influencing the FA value for any molecule is the molar mass of the molecule being measured. As a result, the FA method with functional nucleic acid aptamers has been limited to macromolecules such as proteins and is generally not applicable for the analysis of small molecules because their molecular masses are relatively too small to produce observable FA value changes. We report here a molecular mass amplifying strategy to construct anisotropy aptamer probes for small molecules. The probe is designed in such a way that only when a target molecule binds to the probe does it activate its binding ability to an anisotropy amplifier (a high molecular mass molecule such as protein), thus significantly increasing the molecular mass and FA value of the probe/target complex. Specifically, a mass amplifying probe (MAP) consists of a targeting aptamer domain against a target molecule and molecular mass amplifying aptamer domain for the amplifier protein. The probe is initially rendered inactive by a small blocking strand partially complementary to both target aptamer and amplifier protein aptamer so that the mass amplifying aptamer domain would not bind to the amplifier protein unless the probe has been activated by the target. In this way, we prepared two probes that constitute a target (ATP and cocaine respectively) aptamer, a thrombin (as the mass amplifier) aptamer, and a fluorophore. Both probes worked well against their corresponding small molecule targets, and the detection limits for ATP and cocaine were 0.5 μM and 0.8 μM, respectively. More importantly, because FA is less affected by environmental interferences, ATP in cell media and cocaine in urine were directly detected without any tedious sample pretreatment. Our results established that our molecular mass amplifying strategy can be used to design aptamer probes for rapid, sensitive, and selective

  18. Synthesis and application of a highly selective copper ions fluorescent probe based on the coumarin group

    Science.gov (United States)

    He, Guangjie; Liu, Xiangli; Xu, Jinhe; Ji, Liguo; Yang, Linlin; Fan, Aiying; Wang, Songjun; Wang, Qingzhi

    2018-02-01

    A highly selective copper ions fluorescent probe based on the coumarin-type Schiff base derivative 1 (probe) was produced by condensation reaction between coumarin carbohydrazide and 1H-indazole-3-carbaldehyde. The UV-vis spectroscopy showed that the maximum absorption peak of compound 1 appeared at 439 nm. In the presence of Cu2 + ions, the maximum peak decreased remarkably compared with other physiological important metal ions and a new absorption peak at 500 nm appeared. The job's plot experiments showed that complexes of 1:2 binding mode were formed in CH3CN:HEPES (3:2, v/v) solution. Compound 1 exhibited a strong blue fluorescence. Upon addition of copper ions, the fluorescence gradually decreased and reached a plateau with the fluorescence quenching rate up to 98.73%. The detection limit for Cu2 + ions was estimated to 0.384 ppm. Fluorescent microscopy experiments demonstrated that probe 1 had potential to be used to investigate biological processes involving Cu2 + ions within living cells.

  19. Molecular engineering of two-photon fluorescent probes for bioimaging applications

    Science.gov (United States)

    Liu, Hong-Wen; Liu, Yongchao; Wang, Peng; Zhang, Xiao-Bing

    2017-03-01

    During the past two decades, two-photon microscopy (TPM), which utilizes two near-infrared photons as the excitation source, has emerged as a novel, attractive imaging tool for biological research. Compared with one-photon microscopy, TPM offers several advantages, such as lowering background fluorescence in living cells and tissues, reducing photodamage to biosamples, and a photobleaching phenomenon, offering better 3D spatial localization, and increasing penetration depth. Small-molecule-based two-photon fluorescent probes have been well developed for the detection and imaging of various analytes in biological systems. In this review, we will give a general introduction of molecular engineering of two-photon fluorescent probes based on different fluorescence response mechanisms for bioimaging applications during the past decade. Inspired by the desired advantages of small-molecule two-photon fluorescent probes in biological imaging applications, we expect that more attention will be devoted to the development of new two-photon fluorophores and applications of TPM in areas of bioanalysis and disease diagnosis.

  20. Preparation of fluorescent DNA probe by solid-phase organic synthesis

    Directory of Open Access Journals (Sweden)

    2009-08-01

    Full Text Available Fluorescent DNA probe based on fluorescence resonance energy transfer (FRET was prepared by solid-phase organic synthesis when CdTe quantum dots (QDs were as energy donors and Au nanoparticles (AuNPs were as energy accepters. The poly(divinylbenzene core/poly(4-vinylpyridine shell microspheres, as solid-phase carriers, were prepared by seeds distillation-precipitation polymerization with 2,2′-azobisisobutyronitrile (AIBN as initiator in neat acetonitrile. The CdTe QDs and AuNPs were self-assembled on the surface of core/shell microspheres, and then the linkage of CdTe QDs with oligonucleotides (CdTe-DNA and AuNPs with complementary single-stranded DNA (Au-DNA was on the solid-phase carriers instead of in aqueous solution. The hybridization of complementary double stranded DNA (dsDNA bonded to the QDs and AuNPs (CdTe-dsDNA-Au determined the FRET distance of CdTe QDs and AuNPs. Compared with the fluorescence of CdTe-DNA, the fluorescence of CdTe-dsDNA-Au conjugates (DNA probes decreased extremely, which indicated that the FRET occurred between CdTe QDs and AuNPs. The probe system would have a certain degree recovery of fluorescence when the complementary single stranded DNA was introduced into this system, which showed that the distance between CdTe QDs and AuNPs was increased.

  1. Newly synthesized benzanthrone derivatives as prospective fluorescent membrane probes

    International Nuclear Information System (INIS)

    Zhytniakivska, Olga; Trusova, Valeriya; Gorbenko, Galyna; Kirilova, Elena; Kalnina, Inta; Kirilov, Georgiy; Kinnunen, Paavo

    2014-01-01

    Fluorescence spectral properties of a series of novel benzanthrone derivatives have been explored in lipid bilayers composed of zwitterionic lipid phosphatidylcholine (PC) and its mixtures with cholesterol (Chol) and anionic phospholipid cardiolipin (CL). Analysis of partition coefficients showed that all the examined compounds possess rather high lipid-associating ability, with the amidino derivatives exhibiting stronger membrane partitioning compared with the aminobenzanthrones. To understand how benzanthrone partition properties correlate with their structure, quantitative structure property relationship (QSPR) analysis was performed involving a range of quantum chemical molecular descriptors. -- Highlights: • Benzanthrone partitioning into lipid bilayer correlates with lipophilicity of the dyes. • Partition properties of benzanthrones depend on the dye dipole moment. • Amidino derivatives exhibit higher membrane affinity than aminobenzanthrones

  2. MUC1 aptamer based near infrared fluorescence probes for tumor diagnosis

    Science.gov (United States)

    Zhao, Juan; Ma, Yuxiang; Cui, Sisi; Cao, Jie; Achilefu, Samuel; Gu, Yueqing

    2013-02-01

    Mucin 1 (MUC1) is a cell surface mucin broadly expressed in mucosal tissues. The aberrant expression of MUC1 under-glycosylated forms has been reported in various carcinomas of the epithelium, such as breast, pancreatic and ovarian cancers. Using the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) methodology, aptamers previously selected against MUC1 glycoprotein with high affinities and specificities. In this study, we developed two targeted near-infrared fluorescent probes for tumor in-vivo diagnostics using a MUC1 aptamer(APT) as targeted ligand and near-infrared fluorescent dye (ICG-Der-02) as labelling. MUC1 aptamer conjugated ICG-Der-02 (APT-ICG-Der-02) displayed a great selectivity to MUC1 positive cell line MCF7 and MCF7 xenograft-bearing nude mice. To improve the high targeting of the probe to the tumor cells, PEG, with high biocompatibility, non immunogenicity and long circulation, was conjugated to the probe .The new probe (APT-PEG-ICG-Der-02) showed better tumour uptake and clearance, and also displayed a great selectivity to MCF7 tumor-bearing nude mice. Data obtained demonstrate a high potential of the targeted near-infrared fluorescent probes in cancer early diagnosis.

  3. Folate receptor targeting silica nanoparticle probe for two-photon fluorescence bioimaging

    Science.gov (United States)

    Wang, Xuhua; Yao, Sheng; Ahn, Hyo-Yang; Zhang, Yuanwei; Bondar, Mykhailo V.; Torres, Joseph A.; Belfield, Kevin D.

    2010-01-01

    Narrow dispersity organically modified silica nanoparticles (SiNPs), diameter ~30 nm, entrapping a hydrophobic two-photon absorbing fluorenyl dye, were synthesized by hydrolysis of triethoxyvinylsilane and (3-aminopropyl)triethoxysilane in the nonpolar core of Aerosol-OT micelles. The surface of the SiNPs were functionalized with folic acid, to specifically deliver the probe to folate receptor (FR) over-expressing Hela cells, making these folate two-photon dye-doped SiNPs potential candidates as probes for two-photon fluorescence microscopy (2PFM) bioimaging. In vitro studies using FR over-expressing Hela cells and low FR expressing MG63 cells demonstrated specific cellular uptake of the functionalized nanoparticles. One-photon fluorescence microscopy (1PFM) imaging, 2PFM imaging, and two-photon fluorescence lifetime microscopy (2P-FLIM) imaging of Hela cells incubated with folate-modified two-photon dye-doped SiNPs were demonstrated. PMID:21258480

  4. How to study picosecond solvation dynamics using fluorescent probes with small Stokes shifts

    Science.gov (United States)

    Silori, Yogita; Dey, Shivalee; De, Arijit K.

    2018-02-01

    Xanthene dyes have wide ranging applications as fluorescent probes in analytical, biochemical and medical contexts. Being cationic/anionic in nature, the solvation dynamics of xanthene dyes confined within a negatively/positively charged interface are very interesting. Unfortunately, the floppy structure and small Stokes shift render any xanthene dye unsuitable for use as a solvation probe. Using di-sodium fluorescein, we present our work on the picosecond solvation dynamics of bulk and confined water (at pH = 9.2). We also propose a new methodology for studying picosecond solvation dynamics using any fluorescent dye with a small Stokes shift. We discuss how scattering contributions can be effectively removed, and propose an alternative way of defining zero time of solvation. Finally, we demonstrate the tuning location of the probe within confinement.

  5. Hydrogen sulfide and resolution of acute inflammation: A comparative study utilizing a novel fluorescent probe.

    Science.gov (United States)

    Dufton, Neil; Natividad, Jane; Verdu, Elena F; Wallace, John L

    2012-01-01

    Hydrogen sulfide is an essential gasotransmitter associated with numerous pathologies. We assert that hydrogen sulfide plays an important role in regulating macrophage function in response to subsequent inflammatory stimuli, promoting clearance of leukocyte infiltrate and reducing TNF-α levels in vivo following zymosan-challenge. We describe two distinct methods of measuring leukocyte hydrogen sulfide synthesis; methylene blue formation following zinc acetate capture and a novel fluorescent sulfidefluor probe. Comparison of these methods, using pharmacological tools, revealed they were complimentary in vitro and in vivo. We demonstrate the application of sulfidefluor probe to spectrofluorimetry, flow cytometry and whole animal imaging, to monitor the regulation of hydrogen sulfide synthesis in vivo during dynamic inflammatory processes. Both methodologies revealed that granulocyte infiltration negatively affects hydrogen sulfide synthesis. Our report offers an insight into the profile of hydrogen sulfide synthesis during inflammation and highlight opportunities raised by the development of novel fluorescent hydrogen sulfide probes.

  6. Sensitive and Selective Ratiometric Fluorescence Probes for Detection of Intracellular Endogenous Monoamine Oxidase A.

    Science.gov (United States)

    Wu, Xiaofeng; Li, Lihong; Shi, Wen; Gong, Qiuyu; Li, Xiaohua; Ma, Huimin

    2016-01-19

    Monoamine oxidase A (MAO-A) is known to widely exist in most cell lines in the body, and its dysfunction (unusually high or low levels of MAO-A) is thought to be responsible for several psychiatric and neurological disorders. Thus, a sensitive and selective method for evaluating the relative MAO-A levels in different live cells is urgently needed to better understand the function of MAO-A, but to our knowledge such a method is still lacking. Herein, we rationally design two new ratiometric fluorescence probes (1 and 2) that can sensitively and selectively detect MAO-A. The probes are constructed by incorporating a recognition group of propylamine into the fluorescent skeleton of 1,8-naphthalimide, and the detection mechanism is based on amine oxidation and β-elimination to release the fluorophore (4-hydroxy-N-butyl-1,8-naphthalimide), which is verified by HPLC analysis. Reaction of the probes with MAO-A produces a remarkable fluorescence change from blue to green, and the ratio of fluorescence intensity at 550 and 454 nm is directly proportional to the concentration of MAO-A in the ranges of 0.5-1.5 and 0.5-2.5 μg/mL with detection limits of 1.1 and 10 ng/mL (k = 3) for probes 1 and 2, respectively. Surprisingly, these probes show strong fluorescence responses to MAO-A but almost none to MAO-B (one of two isoforms of MAO), indicating superior ability to distinguish MAO-A from MAO-B. The high specificity of the probes for MAO-A over MAO-B is further supported by different inhibitor experiments. Moreover, probe 1 displays higher sensitivity than probe 2 and is thus investigated to image the relative MAO-A levels in different live cells, such as HeLa and NIH-3T3 cells. It is found that the concentration of endogenous MAO-A in HeLa cells is approximately 1.8 times higher than that in NIH-3T3 cells, which is validated by the result from an ELISA kit. Additionally, the proposed probes may find more uses in the specific detection of MAO-A between the two isoforms of MAO

  7. Quantitative imaging of glutathione in live cells using a reversible reaction-based ratiometric fluorescent probe.

    Science.gov (United States)

    Jiang, Xiqian; Yu, Yong; Chen, Jianwei; Zhao, Mingkun; Chen, Hui; Song, Xianzhou; Matzuk, Alexander J; Carroll, Shaina L; Tan, Xiao; Sizovs, Antons; Cheng, Ninghui; Wang, Meng C; Wang, Jin

    2015-03-20

    Glutathione (GSH) plays an important role in maintaining redox homeostasis inside cells. Currently, there are no methods available to quantitatively assess the GSH concentration in live cells. Live cell fluorescence imaging revolutionized the field of cell biology and has become an indispensable tool in current biological studies. In order to minimize the disturbance to the biological system in live cell imaging, the probe concentration needs to be significantly lower than the analyte concentration. Because of this, any irreversible reaction-based GSH probe can only provide qualitative results within a short reaction time and will exhibit maximum response regardless of the GSH concentration if the reaction is completed. A reversible reaction-based probe with an appropriate equilibrium constant allows measurement of an analyte at much higher concentrations and, thus, is a prerequisite for GSH quantification inside cells. In this contribution, we report the first fluorescent probe-ThiolQuant Green (TQ Green)-for quantitative imaging of GSH in live cells. Due to the reversible nature of the reaction between the probe and GSH, we are able to quantify mM concentrations of GSH with TQ Green concentrations as low as 20 nM. Furthermore, the GSH concentrations measured using TQ Green in 3T3-L1, HeLa, HepG2, PANC-1, and PANC-28 cells are reproducible and well correlated with the values obtained from cell lysates. TQ Green imaging can also resolve the changes in GSH concentration in PANC-1 cells upon diethylmaleate (DEM) treatment. In addition, TQ Green can be conveniently applied in fluorescence activated cell sorting (FACS) to measure GSH level changes. Through this study, we not only demonstrate the importance of reaction reversibility in designing quantitative reaction-based fluorescent probes but also provide a practical tool to facilitate redox biology studies.

  8. Bodipy-FL-Verapamil: A Fluorescent Probe for the Study of Multidrug Resistance Proteins

    Directory of Open Access Journals (Sweden)

    Anna Rosati

    2004-01-01

    Full Text Available Most of the substances used as fluorescent probes to study drug transport and the effect of efflux blockers in multidrug resistant cells have many drawbacks, such as toxicity, unspecific background, accumulation in mitochondria. New fluorescent compounds, among which Bodipy‐FL‐verapamil (BV, have been therefore proposed as more useful tools. The uptake of BV has been evaluated by cytofluorimetry and fluorescence microscopy using cell lines that overexpress P‐glycoprotein (P388/ADR and LLC‐PK1/ADR or MRP (multidrug resistance‐related protein (PANC‐1 and clinical specimens from patients. The effect of specific inhibitors for P‐glycoprotein (verapamil and vinblastine or MRP (MK571 and probenecid has been also studied. BV intracellular concentrations were significantly lower in the two P‐glycoprotein overexpressing cell lines in comparison with the parental lines. In addition, verapamil and vinblastine increased the intracellular concentrations of the dye; MK571 and probenecid, two MRP inhibitors, increased BV levels in PANC‐1 cells, that express this protein. These findings were confirmed in clinical specimens from patients. Fluorescence microscopy revealed a faint fluorescence emission in P‐glycoprotein or MRP expressing cell lines; however, treatment with specific inhibitors significantly increased the fluorescence. BV is a useful tool for studying multidrug resistance proteins with different techniques such as cytofluorimetry and fluorescence microscopy, but does not discriminate between P‐glycoprotein and MRP. In comparison with other classic fluorescent probes, the assay with this dye is extremely rapid, simple, not toxic for cells, devoid of fluorescent background, and can be useful in the clinical settings.

  9. The Probing Radio Signal Polarization Effect on Separation Efficiency of Surface Target Response

    Directory of Open Access Journals (Sweden)

    A. N. Pinchuk

    2015-01-01

    Full Text Available The aim of the study was a quantitative analysis of the level of interference with radar monitoring characteristics of surface targets, caused by the scattered electromagnetic field, arising due to the interaction between radio waves and sea surface, which is a study aspect a radiooceanography encompasses. Backscatter signal, arising from the interaction of radio waves and sea surface, extends in a direction opposite the probing radar signal of spread marine and coastal radar stations.With radar sounding of sea surface at high incidence angles of radio waves, a basic physical mechanism to form the received signal is resonant (Bragg scattering, and at small incidence angles of radio waves it is quasi-specular reflection. Consequently, the energy of electromagnetic radiation, backscattered by the sea surface, depends on the type of wave polarization: for horizontal polarization it is less than for vertical one.The paper presents a mathematical model, which describes dependence of interference level caused by interaction between radio waves and sea surface, on the radio wave polarization for the case when the same polarization is used to sent-out and receive a radio wave.To determine the noise reduction to be achievable with radar monitoring the surface targets by selecting the polarization of the probing radar signal, a signal/noise ratio is analyzed for its different polarizations.It is shown that in order to reduce the noise level caused by the interaction between radio waves and sea surface, it is possible to use the differences in the level of scattered radio signals of different polarization: with horizontally-polarized radar operation at incidence angles of 75°- 85° a signal/noise ratio is by 20-35 dB higher than that of vertically- polarized one.

  10. Interactions of egg yolk lipoprotein fraction with boar spermatozoa assessed with a fluorescent membrane probe.

    Directory of Open Access Journals (Sweden)

    Łukasz Zasiadczyk

    2010-08-01

    Full Text Available The interactions of a fluorescent membrane probe, 1-anilinonaphthalene-8-sulfonic acid (1,8-ANS, with boar spermatozoa were followed through the use of lipoprotein fraction of ostrich egg yolk (LPFo. Semen samples, extended in Kortowo 3 (K3 extender, were supplemented with 2% or 5% LPFo and stored for 3h at 16 degrees C. Additionally, cold shock-treated spermatozoa (1h at 4 degrees C were stored in K3 extender supplemented with LPFo for 3h at 16 degrees C. In each boar, the fluorescent enhancement of ANS was observed in K3-extended semen supplemented with LPFo, prior to storage. Following storage, there was a significant increase in LPFo-ANS fluorescence, particularly in the sperm membrane overlying the head and midpiece regions. There were significant differences among the boars with respect to the sperm populations defined by the LPFo-ANS fluorescence. Sperm viability was not significantly affected during the storage period. Furthermore, the proportions of spermatozoa defined by the different patterns of LPFo-ANS fluorescence were low and remained unchanged after storage of cold shock-treated spermatozoa with 2% or 5% LPFo, suggesting irreversible damage to the sperm membrane architecture. These findings indicate that the ANS fluorescent probe could be used to shed more light on the nature of the interactions between LPFo and sperm membrane following semen preservation. Such valuable information could contribute to the development of an optimal protocol for cryopreservation of boar semen.

  11. A mechanosynthesized, sequential, cyclic fluorescent probe for mercury and iodide ions in aqueous solutions

    Science.gov (United States)

    Chen, Shangwen; Wang, Pipi; Jia, Chunmei; Lin, Qiang; Yuan, Wenbing

    2014-12-01

    A fluorescent Hg2+-selective chemosensor, 2,5-dimethoxybenzaldehyde thiosemicarbazone (1), was quantitatively prepared by grinding 2,5-dimethoxybenzaldehyde and thiosemicarbazide together in a ball mill for 15 min. The excitation and emission maxima of compound 1 are 347 and 450 nm, respectively. The reaction of this ligand with Hg2+ was investigated by FT-IR, 1H NMR, and fluorescence titration. Results show that the composition of the resulting Hg complex 1-Hg is 2:1 1:Hg, and that the S and imino N atoms serve as the binding sites of the ligand to the Hg2+ ions. Coordination-assisted fluorescence quenching results show that compound 1 exhibits a highly selective fluorescence response to trace amounts of Hg2+ in water. More importantly, the resulting complex 1-Hg can be used as a turn-on fluorescence probe for I- at a detection limit of 8.4 × 10-8 M. Thus, compound 1 is a relatively stable, sequential, cyclic fluorescent probe for Hg2+ and I-.

  12. A mechanosynthesized, sequential, cyclic fluorescent probe for mercury and iodide ions in aqueous solutions.

    Science.gov (United States)

    Chen, Shangwen; Wang, Pipi; Jia, Chunmei; Lin, Qiang; Yuan, Wenbing

    2014-12-10

    A fluorescent Hg(2+)-selective chemosensor, 2,5-dimethoxybenzaldehyde thiosemicarbazone (1), was quantitatively prepared by grinding 2,5-dimethoxybenzaldehyde and thiosemicarbazide together in a ball mill for 15min. The excitation and emission maxima of compound 1 are 347 and 450nm, respectively. The reaction of this ligand with Hg(2+) was investigated by FT-IR, (1)H NMR, and fluorescence titration. Results show that the composition of the resulting Hg complex 1-Hg is 2:1 1:Hg, and that the S and imino N atoms serve as the binding sites of the ligand to the Hg(2+) ions. Coordination-assisted fluorescence quenching results show that compound 1 exhibits a highly selective fluorescence response to trace amounts of Hg(2+) in water. More importantly, the resulting complex 1-Hg can be used as a turn-on fluorescence probe for I(-) at a detection limit of 8.4×10(-8)M. Thus, compound 1 is a relatively stable, sequential, cyclic fluorescent probe for Hg(2+) and I(-). Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Biomolecular interactions probed by fluorescence resonance energy transfer

    Science.gov (United States)

    Lange, Daniela Charlotte

    2000-09-01

    This thesis describes how a physical phenomenon, Fluorescence Resonance Energy Transfer (FRET), can be exploited for the study of interactions between biomolecules. The physical basis of this phenomenon is discussed and it is described how some of its characteristics can be exploited in measurement. A recently introduced method, photobleaching FRET microscopy, was implemented and its image analysis refined to suit our biological context. Further, a new technique is proposed, which combines FRET with confocal laser scanning microscopy to optimize resolution and to allow for 3D-studies in living cells. The first part of this thesis presents the application of FRET to the study of oligomerization of G-protein coupled receptors (GPCRs), which was performed at the Fraser Laboratories at McGill University in Montreal. It is demonstrated how FRET microscopy allowed us to circumvent problems of traditional biochemical approaches and provided the first direct evidence for GPCR oligomerization in intact cells. We found that somatostatin receptors (SSTRs) functionally interact by forming oligomers with their own kind, with different SSTR isoforms, and even with distantly related GPCRs, such as dopamine receptors, the latter of which is breaking with the dogma that GPCRs would only pair up with their own kind. The high sensitivity of the FRET technique allowed us to characterize these interactions under more physiological conditions, which lead to the observation that oligomerization is induced by receptor agonist. We further studied the differential effects of agonists and antagonists on receptor oligomerization, leading to a model for the molecular mechanism underlying agonist/antagonist function and receptor activation. The second part was carried out at the Neurobiology Laboratory of the VA Medical Center in Newington, CT. The objective was to further our understanding of Niemann- Pick type C disease, which is characterized by a defect in intracellular cholesterol

  14. Determination of deoxynivalenol in wheat bran and whole-wheat flour by fluorescence polarization immunoassay

    Science.gov (United States)

    A rapid and accurate fluorescence polarization (FP) immunoassay has been optimized for the determination of deoxynivalenol (DON) in bran and whole-wheat flour. A preliminary treatment with activated charcoal was used to eliminate the strong matrix effect due to highly colored interfering compounds p...

  15. The interaction of fluorescent nanodiamond probes with cellular media.

    Science.gov (United States)

    Hemelaar, Simon R; Nagl, Andreas; Bigot, François; Rodríguez-García, Melissa M; de Vries, Marcel P; Chipaux, Mayeul; Schirhagl, Romana

    2017-01-01

    Fluorescent nanodiamonds (FNDs) are promising tools to image cells, bioanalytes and physical quantities such as temperature, pressure, and electric or magnetic fields with nanometer resolution. To exploit their potential for intracellular applications, the FNDs have to be brought into contact with cell culture media. The interactions between the medium and the diamonds crucially influence sensitivity as well as the ability to enter cells. The authors demonstrate that certain proteins and salts spontaneously adhere to the FNDs and may cause aggregation. This is a first investigation on the fundamental questions on how (a) FNDs interact with the medium, and (b) which proteins and salts are being attracted. A differentiation between strongly binding and weakly binding proteins is made. Not all proteins participate in the formation of FND aggregates. Surprisingly, some main components in the medium seem to play no role in aggregation. Simple strategies to prevent aggregation are discussed. These include adding the proteins, which are naturally present in the cell culture to the diamonds first and then inserting them in the full medium. Graphical abstractSchematic of the interaction of nanodiamonds with cell culture medium. Certain proteins and salts adhere to the diamond surface and lead to aggregation or to formation of a protein corona.

  16. Two sugar-rhodamine "turn-on" fluorescent probes for the selective detection of Fe3 +

    Science.gov (United States)

    Chen, Qing; Fang, Zhijie

    2018-03-01

    Two new sugar-rhodamine fluorescent probes (RDG1 and RDG2) have been synthesized and characterized by 1H NMR, 13C NMR and HRMS. Their UV-Vis, fluorescence spectra and fluorescence-response to Fe3 + are investigated and discussed. RDG1 had a very nice linear relationship between UV absorbance and Fe3 + concentration with the correlation coefficient as high as 0.997 and the detection limit is 3.46 × 10- 6 M. Upon the addition of Fe3 +, the spirolactam ring of RDG1 was opened and a 1:1 metal ligand complex was formed from Job's plot. The results showed that RDG1 can be used as an effective fluorescent probe for selective detection of Fe3 + in water. RDG2 was incorporated the well-known rhodamine group and a water-soluble D-glucose group within one molecule and can be used for detecting Fe3 + in natural water as a selective fluorescent sensor. The addition of Fe3 + into RDG2 resulted in a strongly enhanced fluorescence as well as color change of solution from colorless to pink. Job's plot of RDG2 indicated 1:1 stoichiometry of RDG2-Fe3 +. RDG2 can serve as a probe for Fe3 + between pH = 4.0 to 7.0 and it's detection limit is 2.09 × 10- 6 M. The OFF-ON fluorescent mechanisms of RDG1-Fe3 + and RDG2-Fe3 + are proposed.

  17. Fluorescence emission and polarization analyses for evaluating binding of ruthenium metalloglycoclusters to lectins and tetanus toxin C-fragment

    Science.gov (United States)

    Okada, Tomoko; Minoura, Norihiko

    2011-03-01

    We develop a fluorescent ruthenium metalloglycocluster for use as a powerful molecular probe in evaluating the binding between carbohydrates and lectins by fluorescence emission (FE) and fluorescence polarization (FP) analyses. Changes in the FE and FP of these metalloglycoclusters are measured following the addition of lectin [peanut agglutinin (PNA), Ricinus communis agglutinin 120, Concanavalin A (ConA), or wheat germ agglutinin] or tetanus toxin c-fragment (TCF). After the addition of PNA, the FE spectrum of [Ru(bpy-2Gal)3] shows a new emission peak and the FP value of [Ru(bpy-2Gal)3] increases. Similarly, the FE spectrum of [Ru(bpy-2Glc)3] shows a new emission peak and the FP value increases on addition of ConA. Because other combinations of metalloglycoclusters and lectins show little change, specific binding of galactose to PNA and that of glucose to ConA are confirmed by the FE and FP measurements. Resulting dissociation constants (Kd) prove that the metalloglycoclusters with highly clustered carbohydrates show higher affinity for the respective lectins than those with less clustered carbohydrates. Furthermore, specific binding of [Ru(bpy-2Gal)3] to TCF was confirmed by the FP measurement.

  18. Molecular Level Understanding of Sodium Dodecyl Sulfate (SDS) Induced Sol-Gel Transition of Pluronic F127 Using Fisetin as a Fluorescent Molecular Probe.

    Science.gov (United States)

    Mishra, Jhili; Swain, Jitendriya; Mishra, Ashok Kumar

    2018-01-11

    The thermoreversible sol-gel transition of pluronic F127 is markedly altered even with addition of submicellar concentration of sodium dodecyl sulfate (SDS) surfactant. Multiple fluorescence parameters like fluorescence intensity, fluorescence anisotropy and fluorescence lifetime of both the prototropic forms (anion (A - *) and phototautomer FT*) of the photoprototropic fluorescent probe fisetin has been efficiently used to understand the molecular level properties like polarity and microviscosity of the PF127-SDS system as a function of temperature. The SDS-induced increase in the interfacial hydrophobicity level is seen to affect the sol-gel phase transition of PF127 (21-18 °C). The E T (30) polarity parameter value of anionic emission of fisetin suggests that there is a considerable decrease in the polarity of the PF127 medium with increase in temperature and with the addition of SDS. The microviscosity progressively increases from ∼5 mPa s (sol state, 10 °C) to ∼22.01 mPa s (gel state 35 °C) in aqueous solution of PF127. The variation in microviscosity with addition of SDS in PF127-SDS mixed system is significant in sol phase whereas in gel phase this variation is significantly less. Temperature dependent fluorescence lifetime of FT* indicates that there is heterogeneity in distribution of fisetin molecules at different domains of PF127. This work also show-cases the sensitivity of fisetin toward change in polarity and change in sol-gel transition temperature of copolymer PF127 with variation in temperature (both forward and reverse directions) and SDS.

  19. Rapid probing of photocatalytic activity on titania-based self-cleaning materials using 7-hydroxycoumarin fluorescent probe

    International Nuclear Information System (INIS)

    Guan Huimin; Zhu Lihua; Zhou Hehui; Tang Heqing

    2008-01-01

    Self-cleaning materials are widely applied, but the available methods for determining their photocatalytic activity are time consuming. A simple analysis method was proposed to evaluate rapidly the photocatalytic activity of self-cleaning materials. This method is based on monitoring of a highly fluorescent product generated by the self-cleaning materials after illumination. Under UV irradiation, holes photo-induced on the surface of self-cleaning materials can oxidize water molecules (or hydroxide ions) adsorbed on the surface to produce hydroxyl radicals, which then quantitatively oxidize coumarin to highly fluorescent 7-hydroxycoumarin. It was observed that the fluorescence intensity of photo-generated 7-hydroxycoumarin at 456 nm (excited at 346 nm) linearly increased with irradiation time, and the fluorescence intensity at a given irradiation time was linearly proportional to the photocatalytic activity of self-cleaning materials. Consequently, the photocatalytic activity of self-cleaning materials was able to be probed simply by using this new method, which requires an analysis time of 40 min, being much less than 250 min required for a dye method

  20. A Fluorescence Polarization Assay To Detect Steroid Hormone Traces in Milk.

    Science.gov (United States)

    Varriale, Antonio; Pennacchio, Anna; Pinto, Gabriella; Oliviero, Giorgia; D'Errico, Stefano; Majoli, Adelia; Scala, Andrea; Capo, Alessandro; Pennacchio, Angela; Di Giovanni, Stefano; Staiano, Maria; D'Auria, Sabato

    2015-10-21

    Steroids are a class of hormones improperly used in livestock as growth-promoting agents. Due to their high risk for human health, the European Union (EU) has strictly forbidden the administration of all natural and synthetic steroid hormones to food-producing animals, and the development of new rapid detection methods are greatly encouraged. This work reports a novel fluorescence polarization assay, ready to use, capable of detecting 17β-estradiol directly in milk samples with a low limit of detection of <10 pmol. It is based on the coupling of monospecific antibodies against 17β-estradiol and fluorophores, capable of modulating the fluorescence polarization emission on the basis of the specific binding of antibodies to fluorescence-labeled 17β-estradiol derivative. The successful detection of 17β-estradiol has disclosed the development of an efficient method, easily extensible to any food matrix and having the potential to become a milestone in food quality and safety.

  1. Fiber-optic polarization diversity detection for rotary probe optical coherence tomography.

    Science.gov (United States)

    Lee, Anthony M D; Pahlevaninezhad, Hamid; Yang, Victor X D; Lam, Stephen; MacAulay, Calum; Lane, Pierre

    2014-06-15

    We report a polarization diversity detection scheme for optical coherence tomography with a new, custom, miniaturized fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the X and Y OCT polarization channels prior to interference and the PM fiber outputs ensure defined X and Y axes after interference. Advantages for this scheme include easier alignment, lower cost, and easier miniaturization compared to designs with free-space bulk optical components. We demonstrate the utility of the detection system to mitigate the effects of rapidly changing polarization states when imaging with rotating fiber optic probes in Intralipid suspension and during in vivo imaging of human airways.

  2. A Sensitive Ratiometric Long-Wavelength Fluorescent Probe for Selective Determination of Cysteine/Homocysteine.

    Science.gov (United States)

    Manibalan, Kesavan; Chen, Sin-Ming; Mani, Veerappan; Huang, Tsung-Tao; Huang, Sheng-Tung

    2016-07-01

    The development of sensitive fluorescence probes to detect biothiols such as cysteine and homocysteine has attracted great attention in recent times. Herein, we described the design and synthesis of coumarin based long-wavelength fluorescence probe, Bromo-2-benzothiazolyl-3-cyano-7-hydroxy coumarin (BBCH, 2) for selective detections of cysteine and homocysteine. The probe is rationally designed in such a way that both sulfhydryl and adjacent amino groups of thiols are involved in sensing process. Only cysteine/homocysteine able to react with BBCH to release fluorescence reporter (BCH, 1); while, glutathione and other amino acids unable to react with BBCH due to the absence of adjacent amino groups. In presence of cysteine, the color of BBCH is turns from colorless to red and thus BBCH is a naked eye fluorescence indicator for cysteine. Besides, BBCH can discriminate cysteine and homocysteine based on color changes and different reaction rates. The described sensing platform showed good sensing performances to detect cysteine and homocysteine with detection limits of 0.87 and 0.19 μM, respectively. Practical applicability was verified in biological and pharmaceutical samples.

  3. Bioimaging of peroxynitrite in MCF-7 cells by a new fluorescent probe rhodamine B phenyl hydrazide.

    Science.gov (United States)

    Ambikapathi, Gopi; Kempahanumakkagari, Suresh Kumar; Ramappa Lamani, Babu; Kuramkote Shivanna, Devaraju; Bodagur Maregowda, Harish; Gupta, Anushree; Malingappa, Pandurangappa

    2013-07-01

    Peroxynitrite is a potent oxidizing and nitrating agent which has detrimental effects on cells by altering the structure and function of biomolecules present within. A fluorescent probe rhodamine B phenyl hydrazide (RBPH) has been proposed for peroxynitrite (ONOO(-)) imaging in MCF-7 cells based on its oxidation property, which converts RBPH to pink colored and highly fluorescent rhodamine B. The fluorescence emission intensity of the rhodamine B produced in the above process is linearly related to the concentration of peroxynitrite. The method obeys Beer's law in the concentration range 2-20 nM and the detection limit has been found to be 1.4 nM. The possible reaction mechanism of peroxynitrite with RBPH to produce rhodamine B has been discussed with spectroscopic evidence. The Probe is selective to the peroxynitrite in the pH range 6-8 which is near physiological pH. Fluorescence microscopic studies suggest that the probe is cell permeable and hence peroxynitrite was imaged in MCF-7 cells.

  4. Fluorescent coumarin-based probe for cysteine and homocysteine with live cell application

    Science.gov (United States)

    Wei, Ling-Fang; Thirumalaivasan, Natesan; Liao, Yu-Cheng; Wu, Shu-Pao

    2017-08-01

    Cysteine (Cys) and homocysteine (Hcy) are two of important biological thiols and function as important roles in several biological processes. The development of Cys and Hcy probes will help to explore the functions of biothiols in biological systems. In this work, a new coumarin-based probe AC, containing an acryloyl moiety, was developed for Cys and Hcy detection in cells. Cys and Hcy undergo a nucleophilic addition and subsequent cyclization reaction to remove to the acryloyl group and yield a fluorescent product, 7-hydroxylcomuarin. The probe AC showed good selectivity for cysteine and homocysteine over glutathione and other amino acids and had low detection limits of 65 nM for Cys and 79 nM for Hcy, respectively. Additionally, confocal imaging experiments demonstrated that the probe AC can be applied to visualize Cys and Hcy in living cells.

  5. Understanding the Selectivity of a Multichannel Fluorescent Probe for Peroxynitrite Over Hypochlorite.

    Science.gov (United States)

    Zhang, Quanjuan; Zhang, Na; Long, Yi-Tao; Qian, Xuhong; Yang, Youjun

    2016-02-17

    Peroxynitrite is a prominent biological reactive nitrogen species from radical combination of nitric oxide and superoxide and fundamentally involved in broad spectrum physiological and pathological processes. Though redox-inert itself, peroxynitrite anion (OONO(-)) attacks various biological electrophiles to generate an array of potent 2-e(-) or 1-e(-) oxidants, which result in cell injuries. Development of fluorescent probes for peroxynitrite, free from interference from hypochlorite, has been an active endeavor of the chemical community. We previously reported a peroxynitrite probe (PN600), which could differentiate hypochlorite from peroxynitrite through a multichannel signaling mechanism. Herein, this intriguing selectivity was accounted for through a structure-reactivity relationship study. Also, this work, together with rich literature contributions, has allowed a qualitative guideline in the use of electron-rich aromatic moieties to design probes against peroxynitrite and/or hypochlorite. The viability of this guideline was further testified by development of another list of peroxynitrite selective probes.

  6. A Fluorescent Probe for Detecting Mycobacterium tuberculosis and Identifying Genes Critical for Cell Entry

    Science.gov (United States)

    Yang, Dong; Ding, Feng; Mitachi, Katsuhiko; Kurosu, Michio; Lee, Richard E.; Kong, Ying

    2016-01-01

    The conventional method for quantitating Mycobacterium tuberculosis (Mtb) in vitro and in vivo relies on bacterial colony forming unit (CFU) enumeration on agar plates. Due to the slow growth rate of Mtb, it takes 3–6 weeks to observe visible colonies on agar plates. Imaging technologies that are capable of quickly quantitating both active and dormant tubercle bacilli in vitro and in vivo would accelerate research toward the development of anti-TB chemotherapies and vaccines. We have developed a fluorescent probe that can directly label the Mtb cell wall components. The fluorescent probe, designated as DLF-1, has a strong affinity to the D-Ala-D-Ala unit of the late peptidoglycan intermediates in the bacterial cell wall. We demonstrate that DLF-1 is capable of detecting Mtb in both the actively replicating and dormant states in vitro at 100 nM without inhibiting bacterial growth. The DLF-1 fluorescence signal correlated well with CFU of the labeled bacteria (R2 = 1 and 0.99 for actively replicating and dormant Mtb, respectively). DLF-1 can also quantitate labeled Mtb inside of cells. The utility of DLF-1 probe to quantitate Mtb was successfully applied to identify genes critical for cell invasion. In conclusion, this novel near infrared imaging probe provides a powerful new tool for enumerating Mtb with potential future use in bacterial virulence study. PMID:28066347

  7. A Fluorescent Probe for Detecting Mycobacterium tuberculosis and Identifying Genes Critical for Cell Entry

    Directory of Open Access Journals (Sweden)

    Dong Yang

    2016-12-01

    Full Text Available ABSTRACTThe conventional method for quantitating Mycobacterium tuberculosis (Mtb in vitro and in vivo relies on bacterial colony forming unit (CFU enumeration on agar plates. Due to the slow growth rate of Mtb, it takes 3-6 weeks to observe visible colonies on agar plates. Imaging technologies that are capable of quickly quantitating both active and dormant tubercle bacilli in vitro and in vivo would accelerate research towards the development of anti-TB chemotherapies and vaccines. We have developed a fluorescent probe that can directly label the Mtb cell wall components. The fluorescent probe, designated as DLF-1, has a strong affinity to the D-Ala-D-Ala unit of the late peptidoglycan intermediates in the bacterial cell wall. We demonstrate that DLF-1 is capable of detecting Mtb in both the active replicating and dormant states in vitro at 100 nM without inhibiting bacterial growth. The DLF-1 fluorescence signal correlated well with CFU of the labeled bacteria (R2=1 and 0.99 for active replicating and dormant Mtb, respectively. DLF-1 can also quantitate labeled Mtb inside of cells. The utility of DLF-1 probe to quantitate Mtb was also successfully applied to identify genes critical for cell invasion. In conclusion, this novel near infrared imaging probe provides a powerful new tool for enumerating Mtb with potential future use in bacterial virulence study.

  8. Unusual Fluorescent Responses of Morpholine-functionalized Fluorescent Probes to pH via Manipulation of BODIPY's HOMO and LUMO Energy Orbitals for Intracellular pH Detection.

    Science.gov (United States)

    Zhang, Jingtuo; Yang, Mu; Mazi, Wafa; Adhikari, Kapil; Fang, Mingxi; Xie, Fei; Valenzano, Loredana; Tiwari, Ashutosh; Luo, Fen-Tair; Liu, Haiying

    2016-02-26

    Three uncommon morpholine-based fluorescent probes ( A , B and C ) for pH were prepared by introducing morpholine residues to BODIPY dyes at 4,4'- and 2,6-positions, respectively. In contrast to morpholine-based fluorescent probes for pH reported in literature, these fluorescent probes display high fluorescence in a basic condition while they exhibit very weak fluorescence in an acidic condition. The theoretical calculation confirmed that morpholine is unable to function as either an electron donor or an electron acceptor to quench the BODIPY fluorescence in the neutral and basic condition via photo-induced electron transfer (PET) mechanism because the LUMO energy of morpholine is higher than those of the BODIPY dyes while its HOMO energy is lower than those of the BODIPY dyes. However, the protonation of tertiary amines of the morpholine residues in an acidic environment leads to fluorescence quenching of the BODIPY dyes via d-PET mechanism. The fluorescence quenching is because the protonation effectively decreases the LUMO energy which locates between the HOMO and LUMO energies of the BODIPY dyes. Fluorescent probe C with deep-red emission has been successfully used to detect pH changes in mammalian cells.

  9. Intrinsically Labeled Fluorescent Oligonucleotide Probes on Quantum Dots for Transduction of Nucleic Acid Hybridization.

    Science.gov (United States)

    Shahmuradyan, Anna; Krull, Ulrich J

    2016-03-15

    Quantum dots (QDs) have been widely used in chemical and biosensing due to their unique photoelectrical properties and are well suited as donors in fluorescence resonance energy transfer (FRET). Selective hybridization interactions of oligonucleotides on QDs have been determined by FRET. Typically, the QD-FRET constructs have made use of labeled targets or have implemented labeled sandwich format assays to introduce dyes in proximity to the QDs for the FRET process. The intention of this new work is to explore a method to incorporate the acceptor dye into the probe molecule. Thiazole orange (TO) derivatives are fluorescent intercalating dyes that have been used for detection of double-stranded nucleic acids. One such dye system has been reported in which single-stranded oligonucleotide probes were doubly labeled with adjacent thiazole orange derivatives. In the absence of the fully complementary (FC) oligonucleotide target, the dyes form an H-aggregate, which results in quenching of fluorescence emission due to excitonic interactions between the dyes. The hybridization of the FC target to the probe provides for dissociation of the aggregate as the dyes intercalate into the double stranded duplex, resulting in increased fluorescence. This work reports investigation of the dependence of the ratiometric signal on the type of linkage used to conjugate the dyes to the probe, the location of the dye along the length of the probe, and the distance between adjacent dye molecules. The limit of detection for 34mer and 90mer targets was found to be identical and was 10 nM (2 pmol), similar to analogous QD-FRET using labeled oligonucleotide target. The detection system could discriminate a one base pair mismatch (1BPM) target and was functional without substantial compromise of the signal in 75% serum. The 1BPM was found to reduce background signal, indicating that the structure of the mismatch affected the environment of the intercalating dyes.

  10. Flow cytometric analysis of the granulocyte respiratory burst: a comparison study of fluorescent probes.

    Science.gov (United States)

    Vowells, S J; Sekhsaria, S; Malech, H L; Shalit, M; Fleisher, T A

    1995-01-13

    Chronic granulomatous disease (CGD) is a rare recessive disorder caused by defects in the NADPH oxidase enzyme complex of phagocytes (neutrophils, eosinophils and monocytes). CGD phagocytes fail to produce superoxide and other reactive oxygen species following cell activation (Malech, 1993). The products of oxidase activation can be measured in individual cells by flow cytometry using specific fluorescent probes that increase fluorescence upon oxidation (Trinkle et al., 1987). This approach can be used to confirm a diagnosis of CGD, and to detect the normal/abnormal phagocyte mixture that characterizes the X-linked CGD carrier state. Three fluorescent probes have been described as useful for this purpose: 2'7'-dichlorofluorescin diacetate (DCF) (Bass et al., 1983), 5,6-carboxy-2'7'-dichlorofluorescein diacetate, bis(acetoxymethyl) ester (C-DCF) (Hockenbery et al., 1993) and dihydrorhodamine 123 (DHR) (Rothe et al., 1988; Kinsey et al., 1987). A direct comparison between these three probes has not been reported. In this study we performed a direct comparison between these three probes, evaluating their ability in flow cytometric analysis to maximize fluorescent separation between activated CGD patient and normal granulocytes. Using a whole blood technique with phorbol myristate acetate (PMA) as an activator, it was found that DHR loaded normal granulocytes had a fluorescence intensity which, upon activation, was 48-fold higher than that of C-DCF loaded granulocytes and seven-fold higher than DCF loaded granulocytes (P < 0.001). Use of sodium azide to decrease the catabolism of H2O2 enhanced the fluorescence of DCF by 140%, C-DCF by 45% and DHR by 25%, suggesting that DCF is primarily sensitive to H2O2. DCF and DHR were then evaluated for sensitivity in the detection of small percentages of normal cells in a CGD/normal granulocyte mixture. Normal sub-populations as small as 0.1% could clearly be distinguished using DHR, while DCF was insensitive at this level. Based

  11. Spin polarized auger electron spectroscopy (SPAES): An element specific local magnetization probe of magnetic materials

    Science.gov (United States)

    Anilturk, Onder S.

    Spin Polarized Auger Electron Spectroscopy (SPAES) is found to have application for investigating fundamental properties as well as element specific local magnetization information on magnetic materials. By using the uniqueness of the UTA-SEMPA tool, one can obtain the surface magnetic domain microstructure and also perform SPAES studies by probing a single domain at the surface. In the current study, knowing the probed domain, spin polarization of electrons from super Coster-Kronig MVV Auger emissions on 3%Si-Fe sheets have been investigated. It is observed that on both sides of 180° domains, separated by a domain wall with an out-of-plane component of magnetization, the spin polarized Auger spectra exhibit similar distributions with high polarization structures, which are consistent with the published data. The element specificity of the system is applied to Gd-Co composite system. Details of 4d core hole initiated Auger transitions showed that the 5d states have enhanced spin polarization, confirming the coupling of moments in the composite system via 5d states of Gd. It is also unambiguously observed that Co magnetic moments are indeed aligned antiparallel to the Gd ones via 4f-5d positive exchange and 3d-5d hybridization.

  12. Studies of benzothiazole and benzoselenazole squaraines as fluorescent probes for albumins detection.

    Science.gov (United States)

    Volkova, Kateryna D; Kovalska, Vladyslava B; Losytskyy, Mykhaylo Yu; Bento, Artur; Reis, Lucinda V; Santos, Paulo F; Almeida, Paulo; Yarmoluk, Sergiy M

    2008-09-01

    Series of squaraine benzothiazole and benzoselenazole dyes were studied as possible fluorescent probes for the detection of proteins, particularly albumins. It was shown that majority of the studied squaraines give significant fluorescent response on the human serum albumin (HSA) and bovine serum albumin presence. For squaraine dyes with N-hexyl pendent groups (P-1, P-2, P-3, P-5) about 100-540-fold fluorescence intensity increase upon albumins addition was observed. At the same time in presence of other proteins, namely insulin, avidin from hen egg white, immunoglobulin G (IgG), carbonic anhydrase fluorescence enhancement values were considerably lower -up to 43 times in IgG presence. It was noted that generally, squaraines with long N-hexyl pendent groups demonstrate higher emission increase values upon proteins addition comparing with their analogues with short N-ethyl tails. It was shown that fluorescence intensity enhancement for benzothiazole squaraine dye P-3, relates linearly to the HSA concentration over the wide range-from 0.2 to 500 microg/ml. Together with noticeable selectivity of this dye to albumins, existence of wide dynamic range gives possibility to propose P-3 dye as probe for HSA quantification.

  13. Hairpin-like fluorescent probe for imaging of NF-κB transcription factor activity.

    Science.gov (United States)

    Metelev, Valeri; Zhang, Surong; Tabatadze, David; Bogdanov, Alexei

    2011-04-20

    Three oligodeoxyribonucleotides (ODN) covalently labeled with near-infrared (NIR) fluorochromes were synthesized and characterized with a goal of comparing in vitro a hairpin-based and a duplex-based FRET probe designed for the detection of human recombinant NF-κB p50/p65 heterodimer binding to DNA. Using deoxyguanosine phosphoramidite with a phosphorus-linked aminoethylene (diethylene glycol) hydrophilic linker, we synthesized ODNs with internucleoside reactive sites. The hairpin loop amino linker was modified with IRDye 800CW (FRET acceptor), and the 3'-end was modified with Cy5.5 (FRET donor) using a dithio-linker. To obtain a duplex probe, we conjugated Cy5.5 and 800CW to complementary strands at the distance of ten base pairs in the resultant duplex. No quenching of dyes was observed in either probe. The FRET efficiency was higher in the duplex (71%) than in the hairpin (56%) due to a more favorable distance between the donor and the acceptor. However, the hairpin design allowed more precise ratiometric measurement of fluorescence intensity changes as a result of NF-κB p50/p65 binding to the probe. We determined that as a result of binding there was a statistically significant increase of fluorescence intensity of Cy5.5 (donor) due to a decrease of FRET if normalized by 800CW intensity measured independently of FRET. We conclude that the hairpin based probe design allows for the synthesis of a dual fluorescence imaging probe that renders signal changes that are simple to interpret and stoichiometrically correct for detecting transcription factor-DNA interactions.

  14. Near-infrared fluorescent probes in cancer imaging and therapy: an emerging field

    Science.gov (United States)

    Yi, Xiaomin; Wang, Fuli; Qin, Weijun; Yang, Xiaojian; Yuan, Jianlin

    2014-01-01

    Near-infrared fluorescence (NIRF) imaging is an attractive modality for early cancer detection with high sensitivity and multi-detection capability. Due to convenient modification by conjugating with moieties of interests, NIRF probes are ideal candidates for cancer targeted imaging. Additionally, the combinatory application of NIRF imaging and other imaging modalities that can delineate anatomical structures extends fluorometric determination of biomedical information. Moreover, nanoparticles loaded with NIRF dyes and anticancer agents contribute to the synergistic management of cancer, which integrates the advantage of imaging and therapeutic functions to achieve the ultimate goal of simultaneous diagnosis and treatment. Appropriate probe design with targeting moieties can retain the original properties of NIRF and pharmacokinetics. In recent years, great efforts have been made to develop new NIRF probes with better photostability and strong fluorescence emission, leading to the discovery of numerous novel NIRF probes with fine photophysical properties. Some of these probes exhibit tumoricidal activities upon light radiation, which holds great promise in photothermal therapy, photodynamic therapy, and photoimmunotherapy. This review aims to provide a timely and concise update on emerging NIRF dyes and multifunctional agents. Their potential uses as agents for cancer specific imaging, lymph node mapping, and therapeutics are included. Recent advances of NIRF dyes in clinical use are also summarized. PMID:24648733

  15. A water-soluble rhodamine B-derived fluorescent probe for pH monitoring and imaging in acidic regions

    Science.gov (United States)

    Cui, Peng; Jiang, Xuekai; Sun, Junyong; Zhang, Qiang; Gao, Feng

    2017-06-01

    A structurally simple, water-soluble rhodamine-derivatived fluorescent probe, which is responsive to acidic pH, was conveniently synthesized via a one-step condensation reaction of rhodamine B hydrazide and 4-formybenzene-1,3-disulfonate. As a stable and highly sensitive pH sensor, the probe displays an approximately 50-fold fluorescence enhancement over the pH range of 7.16-4.89 as the structure of probe changes from spirocyclic (weak fluorescent) to ring-open (strong fluorescent) with decreasing pH. The synthesized fluorescent probe is applied to the detection of pH changes in vitro and in vivo bioimaging of immortalized gastric cancer cells, with satisfactory results.

  16. Photobleaching kinetics and time-integrated emission of fluorescent probes in cellular membranes

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Christensen, Tanja; Solanko, Lukasz Michal

    2014-01-01

    Since the pioneering work of Hirschfeld, it is known that time-integrated emission (TiEm) of a fluorophore is independent of fluorescence quantum yield and illumination intensity. Practical implementation of this important result for determining exact probe distribution in living cells is often...... rate constants with a memory kernel. This approach results in a time-dependent bleach rate coefficient and is exemplified for fluorescent sterols in restricted intracellular environments, like lipid droplets. We show that for small deviations from the classical exponential bleaching, the TiEm of decay...

  17. An off-on fluorescence probe targeting mitochondria based on oxidation-reduction response for tumor cell and tissue imaging

    Science.gov (United States)

    Yao, Hanchun; Cao, Li; Zhao, Weiwei; Zhang, Suge; Zeng, Man; Du, Bin

    2017-10-01

    In this study, a tumor-targeting poly( d, l-lactic-co-glycolic acid) (PLGA) loaded "off-on" fluorescent probe nanoparticle (PFN) delivery system was developed to evaluate the region of tumor by off-on fluorescence. The biodegradability of the nanosize PFN delivery system readily released the probe under tumor acidic conditions. The probe with good biocompatibility was used to monitor the intracellular glutathione (GSH) of cancer cells and selectively localize to mitochondria for tumor imaging. The incorporated tumor-targeting probe was based on the molecular photoinduced electron transfer (PET) mechanism preventing fluorescence ("off" state) and could be easily released under tumor acidic conditions. However, the released tumor-targeting fluorescence probe molecule was selective towards GSH with high selectivity and an ultra-sensitivity for the mitochondria of cancer cells and tissues significantly increasing the probe molecule fluorescence signal ("on" state). The tumor-targeting fluorescence probe showed sensitivity to GSH avoiding interference from cysteine and homocysteine. The PFNs could enable fluorescence-guided cancer imaging during cancer therapy. This work may expand the biological applications of PFNs as a diagnostic reagent, which will be beneficial for fundamental research in tumor imaging. [Figure not available: see fulltext.

  18. A new sensitive and selective fluorescence probe for detection of cyanide.

    Science.gov (United States)

    Duan, Yi-Long; Zheng, Yan-Song

    2013-03-30

    A class of new fluorescence probe α-p-trifluoroacetamidophenyl-4-alkoxycinnamonitrile for detection of cyanide anion was synthesized by the trifluoroacetylation of the fluorophore α-p-aminophenyl-4-alkoxycinnamonitrile. It was found that the probe could selectively detect cyanide anions, even in the presence of hydrogen sulfite and dicarbonate anions which were reported to easily interfere with the detection. The concentration of the cyanide anions that could be detected was as low as 1.0 μM. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Reversible Reaction-Based Fluorescent Probe for Real-Time Imaging of Glutathione Dynamics in Mitochondria.

    Science.gov (United States)

    Chen, Jianwei; Jiang, Xiqian; Zhang, Chengwei; MacKenzie, Kevin R; Stossi, Fabio; Palzkill, Timothy; Wang, Meng C; Wang, Jin

    2017-09-22

    We report a mitochondria-specific glutathione (GSH) probe-designated as Mito-RealThiol (MitoRT)-that can monitor in vivo real-time mitochondrial glutathione dynamics, and apply this probe to follow mitochondrial GSH dynamic changes in living cells for the first time. MitoRT can be utilized in confocal microscopy, super-resolution fluorescence imaging, and flow cytometry systems. Using MitoRT, we demonstrate that cells have a high priority to maintain the GSH level in mitochondria compared to the cytosol not only under normal growing conditions but also upon oxidative stress.

  20. Subunits of highly Fluorescent Protein R-Phycoerythrin as Probes for Cell Imaging and Single-Molecule Detection

    Energy Technology Data Exchange (ETDEWEB)

    Isailovic, Dragan [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    The purposes of our research were: (1) To characterize subunits of highly fluorescent protein R-Phycoerythrin (R-PE) and check their suitability for single-molecule detection (SMD) and cell imaging, (2) To extend the use of R-PE subunits through design of similar proteins that will be used as probes for microscopy and spectral imaging in a single cell, and (3) To demonstrate a high-throughput spectral imaging method that will rival spectral flow cytometry in the analysis of individual cells. We first demonstrated that R-PE subunits have spectroscopic and structural characteristics that make them suitable for SMD. Subunits were isolated from R-PE by high-performance liquid chromatography (HPLC) and detected as single molecules by total internal reflection fluorescence microscopy (TIRFM). In addition, R-PE subunits and their enzymatic digests were characterized by several separation and detection methods including HPLC, capillary electrophoresis, sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE) and HPLC-electrospray ionization mass spectrometry (ESI-MS). Favorable absorption and fluorescence of the R-PE subunits and digest peptides originate from phycoerythrobilin (PEB) and phycourobilin (PUB) chromophores that are covalently attached to cysteine residues. High absorption coefficients and strong fluorescence (even under denaturing conditions), broad excitation and emission fluorescence spectra in the visible region of electromagnetic spectrum, and relatively low molecular weights make these molecules suitable for use as fluorescence labels of biomolecules and cells. We further designed fluorescent proteins both in vitro and in vivo (in Escherichia coli) based on the highly specific attachment of PEB chromophore to genetically expressed apo-subunits of R-PE. In one example, apo-alpha and apo-beta R-PE subunits were cloned from red algae Polisiphonia boldii (P. boldii), and expressed in E. coli. Although expressed apo-subunits formed inclusion

  1. Ratiometric fluorescence polarization as a cytometric functional parameter: theory and practice

    Energy Technology Data Exchange (ETDEWEB)

    Yishai, Yitzhak; Fixler, Dror; Cohen-Kashi, Meir; Zurgil, Naomi; Deutsch, Mordechai [The Biophysical Interdisciplinary Jerome Schottenstein Center for the Research and the Technology of the Cellome, Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel)

    2003-08-07

    The use of ratiometric fluorescence polarization (RFP) as a functional parameter in monitoring cellular activation is suggested, based on the physical phenomenon of fluorescence polarization dependency on emission wavelengths in multiple (at least binary) solutions. The theoretical basis of this dependency is thoroughly discussed and examined via simulation. For simulation, aimed to imitate a fluorophore-stained cell, real values of the fluorescence spectrum and polarization of different single fluorophore solutions were used. The simulation as well as the experimentally obtained values of RFP indicated the high sensitivity of this measure. Finally, the RFP parameter was utilized as a cytometric measure in three exemplary cellular bioassays. In the first, the apoptotic effect of oxLDL in a human Jurkat FDA-stained T cell line was monitored by RFP. In the second, the interaction between cell surface membrane receptors of human T lymphocyte cells was monitored by RFP measurements as a complementary means to the fluorescence resonance energy transfer (FRET) technique. In the third bioassay, cellular thiol level of FDA- and CMFDA-labelled Jurkat T cells was monitored via RFP.

  2. Parallel fluorescent probe synthesis based on the large-scale preparation of BODIPY FL propionic acid.

    Science.gov (United States)

    Katoh, Taisuke; Yoshikawa, Masato; Yamamoto, Takeshi; Arai, Ryosuke; Nii, Noriyuki; Tomata, Yoshihide; Suzuki, Shinkichi; Koyama, Ryoukichi; Negoro, Nobuyuki; Yogo, Takatoshi

    2017-03-01

    We describe a methodology for quick development of fluorescent probes with the desired potency for the target of interest by using a method of parallel synthesis, termed as Parallel Fluorescent Probe Synthesis (Parallel-FPS). BODIPY FL propionic acid 1 is a widely used fluorophore, but it is difficult to prepare a large amount of 1, which hinders its use in parallel synthesis. Optimization of a synthetic scheme enabled us to obtain 50g of 1 in one batch. With this large quantity of 1 in hand, we performed Parallel-FPS of BODIPY FL-labeled ligands for estrogen related receptor-α (ERRα). An initial trial of the parallel synthesis with various linkers provided a potent ligand for ERRα (Reporter IC 50 =80nM), demonstrating the usefulness of Parallel-FPS. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Conception, synthesis and evaluation of fluorescent probes and PET radioligands for the oxytocin and vasopressin receptors

    International Nuclear Information System (INIS)

    Karpenko, Iuliia

    2014-01-01

    In order to better understand the role of OTR and AVPR in ASD, to reveal new features in its pharmacology and signaling and to establish high-throughput screening method on wild-type G protein-coupled receptors, we developed imaging probes for the oxytocin-vasopressin receptors family, namely radiotracers for positron emission tomography and optical probes for fluorescence detection and imaging. The fluorescent ligands have been used to establish TR-FRET binding assay for OTR and to initiate the development the screening assay for the wild-type oxytocin receptor. The PET radiotracers will be shortly tested in mice and monkeys to evaluate their potency in detecting the central oxytocin receptors. (author)

  4. In vitro and in vivo imaging of peroxynitrite by a ratiometric boronate-based fluorescent probe.

    Science.gov (United States)

    Palanisamy, Sathyadevi; Wu, Pei-Yu; Wu, Shou-Cheng; Chen, Yu-Jen; Tzou, Shey-Cherng; Wang, Chih-Hong; Chen, Chiao-Yun; Wang, Yun-Ming

    2017-05-15

    Peroxynitrite (ONOO - ) is an important species involved in many physiopathological processes. Progresses have been made in developing novel fluorescent probes to detect peroxynitrite with relatively high sensitivity and specificity. Herein, we report the synthesis, characterization and biological applications of a new boronate-based fluorescent probe, 4-MB. The studies showed that 4-MB exhibits a dual ratiometric and calorimetric response toward peroxynitrite due to ONOO - -triggered oxidative reaction. A possible mechanism of the oxidation reaction was proposed and the reaction product was isolated and characterized using different spectroscopic methods. We have thoroughly demonstrated the utility of 4-MB for intracellular peroxynitrite imaging. Further, we showed that 4-MB can be potentially employed to visualize exogenous and endogenous peroxynitrite in RAW264.7 macrophages, EAhy926 cells, zebrafish and in live tissues from a high-fat diet-induced obese mouse model. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Structural and functional probing of the biogenic amine transporters by fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Rasmussen, Søren G F; Adkins, Erika M; Carroll, F Ivy

    2003-01-01

    Fluorescence spectroscopy techniques have proven extremely powerful for probing the molecular structure and function of membrane proteins. In this review, it will be described how we have applied a series of these techniques to the biogenic amine transporters, which are responsible for the cleara......Fluorescence spectroscopy techniques have proven extremely powerful for probing the molecular structure and function of membrane proteins. In this review, it will be described how we have applied a series of these techniques to the biogenic amine transporters, which are responsible...... for the clearance of dopamine, norepinephrine, and serotonin from the synaptic cleft. In our studies, we have focused on the serotonin transporter (SERT) for which we have established a purification procedure upon expression of the transporter in Sf-9 insect cells. Importantly, the purified transporter displays...

  6. A new Schiff base based on vanillin and naphthalimide as a fluorescent probe for Ag+ in aqueous solution

    Science.gov (United States)

    Zhou, Yanmei; Zhou, Hua; Ma, Tongsen; Zhang, Junli; Niu, Jingyang

    2012-03-01

    A new Schiff base based on vanillin and naphthalimide was designed and synthesized as fluorescent probe. The probe showed high selectivity for Ag+ over other metal ions such as Pb2+, Na+, K+, Cd2+, Ba2+, Cr3+, Zn2+, Cu2+, Ni2+, Ca2+, Al3+ and Mg2+ in aqueous solution. A new fluorescence emission was observed at 682 nm in the presence of Ag+ ion. The fluorescence intensity quenched with increasing the concentration of Ag+ at 682 nm. The method of job's plot confirmed the 1:2 complex between Ag+ and probe, and the mechanism was proposed.

  7. Maximum entropy analysis of polarized fluorescence decay of (E)GFP in aqueous solution

    Science.gov (United States)

    Novikov, Eugene G.; Skakun, Victor V.; Borst, Jan Willem; Visser, Antonie J. W. G.

    2018-01-01

    The maximum entropy method (MEM) was used for the analysis of polarized fluorescence decays of enhanced green fluorescent protein (EGFP) in buffered water/glycerol mixtures, obtained with time-correlated single-photon counting (Visser et al 2016 Methods Appl. Fluoresc. 4 035002). To this end, we used a general-purpose software module of MEM that was earlier developed to analyze (complex) laser photolysis kinetics of ligand rebinding reactions in oxygen binding proteins. We demonstrate that the MEM software provides reliable results and is easy to use for the analysis of both total fluorescence decay and fluorescence anisotropy decay of aqueous solutions of EGFP. The rotational correlation times of EGFP in water/glycerol mixtures, obtained by MEM as maxima of the correlation-time distributions, are identical to the single correlation times determined by global analysis of parallel and perpendicular polarized decay components. The MEM software is also able to determine homo-FRET in another dimeric GFP, for which the transfer correlation time is an order of magnitude shorter than the rotational correlation time. One important advantage utilizing MEM analysis is that no initial guesses of parameters are required, since MEM is able to select the least correlated solution from the feasible set of solutions.

  8. Thioflavin T as a fluorescence probe for monitoring RNA metabolism at molecular and cellular levels

    OpenAIRE

    Sugimoto, Shinya; Arita-Morioka, Ken-ichi; Mizunoe, Yoshimitsu; Yamanaka, Kunitoshi; Ogura, Teru

    2015-01-01

    The intrinsically stochastic dynamics of mRNA metabolism have important consequences on gene regulation and non-genetic cell-to-cell variability; however, no generally applicable methods exist for studying such stochastic processes quantitatively. Here, we describe the use of the amyloid-binding probe Thioflavin T (ThT) for monitoring RNA metabolism in vitro and in vivo. ThT fluoresced strongly in complex with bacterial total RNA than with genomic DNA. ThT bound purine oligoribonucleotides pr...

  9. A Coumarin-Based Fluorescent Probe as a Central Nervous System Disease Biomarker

    OpenAIRE

    Yap, Ann-Chee; Mahamad, Ummi; Lim, Shen-Yang; Kim, Hae-Jo; Choo, Yeun-Mun

    2014-01-01

    Homocysteine and methylmalonic acid are important biomarkers for diseases associated with an impaired central nervous system (CNS). A new chemoassay utilizing coumarin-based fluorescent probe 1 to detect the levels of homocysteine is successfully implemented using Parkinson's disease (PD) patients' blood serum. In addition, a rapid identification of homocysteine and methylmalonic acid levels in blood serum of PD patients was also performed using the liquid chromatography-mass spectrometry (LC...

  10. The X-ray-fluorescence facility at ANKA, Karlsruhe: Minimum detection limits and micro probe capabilities

    CERN Document Server

    Simon, R; Hagelstein, M

    2003-01-01

    At the recently constructed synchrotron radiation facility ANKA at Karlsruhe, Germany, a beamline partially dedicated to X-ray fluorescence has been constructed where TXRF and micro probe SRXRF experiments can be performed. The beam line with its retractable double multilayer monochromator is described. First measurements on reference samples allow a preliminary characterization of beam line parameters like exploitable energy range and the energy resolution as well as the sensitivity of the set-up in means of minimum detection limits.

  11. Sensing for intracellular thiols by water-insoluble two-photon fluorescent probe incorporating nanogel

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xudong; Zhang, Xin; Wang, Shuangqing; Li, Shayu [Beijing National Laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Hu, Rui, E-mail: hurui@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Li, Yi, E-mail: yili@mail.ipc.ac.cn [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Guoqiang, E-mail: gqyang@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-04-15

    Highlights: • A novel “turn-on” two-photon fluorescent probe based on a π-conjugated triarylboron luminogen was designed and synthesized. • Fast, selective and sensitive detection of biothiols in 100% aqueous solution by simply loaded on a nanogel. • Single-photon and two-photon fluorescent bioimaging of biothiols in NIH/3T3 fibroblasts. - Abstract: A novel “turn-on” two-photon fluorescent probe containing a π-conjugated triarylboron luminogen and a maleimide moiety DMDP-M based on the photo-induced electron transfer (PET) mechanism for biothiol detection was designed and synthesized. By simply loading the hydrophobic DMDP-M on a cross-linked Pluronic{sup ®} F127 nanogel (CL-F127), a probing system DMDP-M/CL-F127 was established, which shows quick response, high selectivity and sensitivity to cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) in aqueous phase. The DMDP-M/CL-F127 system presented the fastest response to Cys with a rate constant of 0.56 min{sup −1}, and the detection limit to Cys was calculated to be as low as 0.18 μM. The DMDP-M/CL-F127 system has been successfully applied to the fluorescence imaging of biothiols in NIH/3T3 fibroblasts either with single-photon or two-photon excitation because of its high biocompatibility and cell-membrane permeability. The present work provides a general, simple and efficient strategy for the application of hydrophobic molecules to sensing biothiols in aqueous phase, and a novel sensing system for intracellular biothiols fitted for both single-photon and two-photon fluorescence imaging.

  12. Silane-Induced N-Polarity in Wires Probed by a Synchrotron Nanobeam.

    Science.gov (United States)

    Salomon, Damien; Messanvi, Agnes; Eymery, Joël; Martínez-Criado, Gema

    2017-02-08

    Noncentrosymmetric one-dimensional structures are key driving forces behind advanced nanodevices. Owing to the critical role of silane injection in creating nanosized architectures, it has become a challenge to investigate the induced local lattice polarity in single GaN wires. Thus, if axial and radial structures are well-grown by a silane-mediated approach, an ideal model to study their polar orientations is formed. By combining synchrotron X-ray fluorescence and X-ray excited optical luminescence, we show here experimental evidence of the role of silane to promote the N-polarity, light emission, and elemental incorporation within single wires. In addition, our experiment demonstrates the ability to spatially examine carrier diffusion phenomena without electrical contacts, opening new avenues for further studies with simultaneous optical and elemental sensitivity at the nanoscale.

  13. [A cell-based detection of ciguatoxin using sodium fluorescence probe].

    Science.gov (United States)

    Yuan, Jian-hui; Yang, Hui; Tang, Huan-wen; Huang, Wei; Xu, Xin-yun; Liu, Jian-jun; Ke, Yue-bin; Cheng, Jin-quan; Zhuang, Zhi-xiong

    2011-04-01

    To establish a cell-based detection method of ciguatoxin using fluorescence assay. Mouse neuroblastoma N-2A cells were exposed to ouabain and veratridine and different concentrations of standard ciguatoxin samples (P-CTX-1) to establish the curvilinear relationship between the toxin dosage and fluorescence intensity using the sodium fluorescence probe CoroNaTM Green. The toxicity curvilinear relationship was also generated between the toxin dosage and cell survival using CCK-8 method. Based on these standard curves, the presence of ciguatoxin was detected in 33 samples of deep-sea coral fish. A correlation was found between the detection results of cell-based fluorescence assay and cytotoxicity assay, whose detection limit reached 103 g/ml and 1012 g/ml, respectively. The cell-based fluorescent assay sensitivity showed a higher sensitivity than cytotoxicity assay with a 2-4 h reduction of the detection time. The cell-based fluorescent assay can quickly and sensitively detect ciguatoxin and may serve as a good option for preliminary screening of the toxin.

  14. Rapid and sensitive determination of clenbuterol in porcine muscle and swine urine using a fluorescent probe

    Science.gov (United States)

    Jing, Xu; Bai, Bing; Zhang, Chenxuan; Wu, Wenying; Du, Liming; Liu, Hailong; Yao, Guojun

    2015-02-01

    The feed additive Clenbuterol hydrochloric acid (CLB) is non-fluorescent, thus it is difficult to quantify through direct fluorescent method. Palmatine (PAL) can react with cucurbit[7]uril (CB[7]) to form stable complexes as a fluorescent probe. Significant quenching of the fluorescence intensity of the CB[7]-PAL complex was observed with the addition of CLB. Based on the significant quenching of the supramolecular complex fluorescence intensity, a novel spectrofluorimetric method with high convenience, selectivity and sensitivity was developed for the determination of CLB. The fluorescence quenching values (ΔF) showed good linear relationship with CLB concentrations from 0.011 μg mL-1 to 4.2 μg mL-1 with a detection limit 0.004 μg mL-1. In this research, an ultrasound treatment replaced the former time-consuming shake method to form stable complexes. The proposed spectrofluorimetric method had been successfully applied to the determination of CLB in porcine muscle and swine urine with good precision and accuracy. The competing reaction and the supramolecular interaction mechanisms between the CLB and PAL as they fight for occupancy of the CB[7] cavity were studied using spectrofluorimetry, 1H NMR, and molecular modeling calculations. Interestingly, results indicate that two stable CB[7]-CLB complexes were formed.

  15. Benzoxazinone derivatives: new fluorescent probes for two-color flow cytometry analysis using one excitation wavelength.

    Science.gov (United States)

    Monsigny, M; Midoux, P; Le Bris, M T; Roche, A C; Valeur, B

    1989-01-01

    A new class of fluorescent dye which upon excitation at 488 nm turns red is shown to be probe-suitable for using in flow cytometry alone or in conjunction with fluorescein derivatives. 7-dimethylamino 3-(p-formylstyryl) 1,4 benzoxazin 2-one is suitable for rendering microorganisms, such as Plasmodium merozoites and cells detectable by flow cytometry, allowing a dual fluorescence analysis when the cells are labelled with suitable fluoresceinylated ligands such as fluorescein labeled neoglycoproteins or antibodies. The synthesis of the new benzoxazinone derivatives is described: p-[beta-(7-dimethylamino 1,4 benzoxazin 2-one 3-yl)-vinyl]-phenylpropenoic acid can be easily activated as a hydroxysuccinimide derivative and linked to amino groups of polypeptides. Hydrophilic polypeptides such as poly-L-lysine or glycosylated polymers combined with this new fluorescent dye are shown to be helpful in analyzing cell surface receptors, in dual fluorescence flow cytometry analysis, using a single excitation wavelength and two sets of compounds labeled with the new benzoxazinone derivative and with fluorescein isothiocyanate, respectively. The new benzoxazinone derivative has a high molar absorbance, a good quantum yield fluorescence when it is bound to hydrophilic polypeptides and its fluorescence intensity is not dependent on pH in the physiological pH range.

  16. Fluorescence detection of glutathione and oxidized glutathione in blood with a NIR-excitable cyanine probe.

    Science.gov (United States)

    Liu, Chang-Hui; Qi, Feng-Pei; Wen, Fu-Bin; Long, Li-Ping; Liu, Ai-Juan; Yang, Rong-Hua

    2018-01-19

    Cyanine has been widely utilized as a near infrared (NIR) fluorophore for detection of glutathione (GSH). However, the excitation of most of the reported cyanine-based probes was less than 800 nm, which inevitably induce biological background absorption and lower the sensitivity, limiting their use for detection of GSH in blood samples. To address this issue, here, a heptamethine cyanine probe (DNIR), with a NIR excitation wavelength at 804 nm and a NIR emission wavelength at 832 nm, is employed for the detection of GSH and its oxidized form (GSSG) in blood. The probe displays excellent selectivity for GSH over GSSG and other amino acids, and rapid response to GSH, in particular a good property for indirect detection of GSSG in the presence of enzyme glutathione reductase and the reducing agent nicotinamideadenine dinucleotide phosphate, without further separation prior to fluorescent measurement. To the best of our knowledge, this is the first attempt to explore NIR fluorescent approach for the simultaneous assay of GSH and GSSG in blood. As such, we expect that our fluorescence sensors with both NIR excitation and NIR emission make this strategy suitable for the application in complex physiological systems.

  17. Quinoline Fluorescent Probes for Zinc - from Diagnostic to Therapeutic Molecules in Treating Neurodegenerative Diseases.

    Science.gov (United States)

    Czaplinska, Barbara; Spaczynska, Ewelina; Musiol, Robert

    2018-01-01

    Fluorescent compounds had gained strong attention due to their wide and appealing applications. Microscopic techniques and visualization are good examples among others. Introduction of fluorescent dyes into microbiology opens the possibility to observe tissues, organisms or organelle with exceptional sensitivity and resolution. Probes for detection of biologically relevant metals as zinc, iron or copper seems to be particularly important for drug design and pharmaceutical sciences. Quinoline derivatives are well known for their good metal affinity and wide spectrum of biological activity. In this regard, molecular sensors built on this scaffold may be useful not only as analytical but also as therapeutic agents. In the present review, application of quinoline moiety in designing of novel fluorescent probes for zinc is presented and discussed. Zinc cations are relevant for vast majority of processes and recently attract a great deal of attention for their role in neurodegenerative diseases. Compounds interacting with Zn2+ may be used for early diagnosis of such disorders, for example the Alzheimer disease. Quinoline-based zinc probes may exert some beneficial role in organism acting as theranostic agents. First preliminary drugs for Alzheimer therapy that are based on quinoline moiety are good example of this trend. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  18. Fluorescence detection of glutathione and oxidized glutathione in blood with a NIR-excitable cyanine probe

    Science.gov (United States)

    Liu, Chang-hui; Qi, Feng-pei; Wen, Fu-bin; Long, Li-ping; Liu, Ai-juan; Yang, Rong-hua

    2018-04-01

    Cyanine has been widely utilized as a near infrared (NIR) fluorophore for detection of glutathione (GSH). However, the excitation of most of the reported cyanine-based probes was less than 800 nm, which inevitably induce biological background absorption and lower the sensitivity, limiting their use for detection of GSH in blood samples. To address this issue, here, a heptamethine cyanine probe (DNIR), with a NIR excitation wavelength at 804 nm and a NIR emission wavelength at 832 nm, is employed for the detection of GSH and its oxidized form (GSSG) in blood. The probe displays excellent selectivity for GSH over GSSG and other amino acids, and rapid response to GSH, in particular a good property for indirect detection of GSSG in the presence of enzyme glutathione reductase and the reducing agent nicotinamideadenine dinucleotide phosphate, without further separation prior to fluorescent measurement. To the best of our knowledge, this is the first attempt to explore NIR fluorescent approach for the simultaneous assay of GSH and GSSG in blood. As such, we expect that our fluorescence sensors with both NIR excitation and NIR emission make this strategy suitable for the application in complex physiological systems.

  19. An Amidochlorin-Based Colorimetric Fluorescent Probe for Selective Cu2+ Detection

    Directory of Open Access Journals (Sweden)

    Wenting Li

    2016-01-01

    Full Text Available The design and synthesis of selective and sensitive chemosensors for the quantification of environmentally and biologically important ionic species has attracted widespread attention. Amidochlorin p6 (ACP; an effective colorimetric and fluorescent probe for copper ions (Cu2+ in aqueous solution derived from methyl pheophorbide-a (MPa was designed and synthesized. A remarkable color change from pale yellow to blue was easily observed by the naked eye upon addition of Cu2+; and a fluorescence quenching was also determined. The research of fluorescent quenching of ACP-Cu2+ complexation showed the detection limit was 7.5 × 10−8 mol/L; which suggested that ACP can act as a high sensitive probe for Cu2+ and can be used to quantitatively detect low levels of Cu2+ in aqueous solution. In aqueous solution the probe exhibits excellent selectivity and sensitivity toward Cu2+ ions over other metal ions (M = Zn2+; Ni2+; Ba2+; Ag+; Co2+; Na+; K+; Mg2+; Cd2+; Pb2+; Mn2+; Fe3+; and Ca2+. The obvious change from pale yellow to blue upon the addition of Cu2+ could make it a suitable “naked eye” indicator for Cu2+.

  20. The N-B Interaction through a Water Bridge: Understanding the Chemoselectivity of a Fluorescent Protein Based Probe for Peroxynitrite.

    Science.gov (United States)

    Chen, Zhi-jie; Tian, Ziqi; Kallio, Karen; Oleson, April L; Ji, Ao; Borchardt, Dan; Jiang, De-en; Remington, S James; Ai, Hui-wang

    2016-04-13

    Boronic acid and esters have been extensively utilized for molecular recognition and chemical sensing. We recently reported a genetically encoded peroxynitrite (ONOO(-))-specific fluorescent sensor, pnGFP, based on the incorporation of a boronic acid moiety into a circularly permuted green fluorescent protein (cpGFP) followed by directed protein evolution. Different from typical arylboronic acids and esters, the chromophore of pnGFP is unreactive to millimolar concentrations of hydrogen peroxide (H2O2). The focus of this study is to explore the mechanism for the observed unusual chemoselectivity of pnGFP toward peroxynitrite over hydrogen peroxide by using site-directed mutagenesis, X-ray crystallography, (11)B NMR, and computational analysis. Our data collectively support that a His residue on the protein scaffold polarizes a water molecule to induce the formation of an sp(3)-hybridized boron in the chromophore, thereby tuning the reactivity of pnGFP with various reactive oxygen and nitrogen species (ROS/RNS). Our study demonstrates the first example of tunable boron chemistry in a folded nonnative protein, which offers wide implications in designing selective chemical probes.

  1. Role of polarization in probing anomalous gauge interactions of the Higgs boson

    International Nuclear Information System (INIS)

    Biswal, Sudhansu S.; Godbole, Rohini M.; Choudhury, Debajyoti; Mamta

    2009-01-01

    We explore the use of polarized e + /e - beams and/or the information on final state decay lepton polarizations in probing the interaction of the Higgs boson with a pair of vector bosons. A model independent analysis of the process e + e - →ffH, where f is any light fermion, is carried out through the construction of observables having identical properties under the discrete symmetry transformations as different individual anomalous interactions. This allows us to probe an individual anomalous term independent of the others. We find that initial state beam polarization can significantly improve the sensitivity to CP-odd couplings of the Z boson with the Higgs boson (ZZH). Moreover, an ability to isolate events with a particular τ helicity, with even 40% efficiency, can improve sensitivities to certain ZZH couplings by as much as a factor of 3. In addition, the contamination from the ZZH vertex contributions present in the measurement of the trilinear Higgs-W (WWH) couplings can be reduced to a great extent by employing polarized beams. The effects of initial state radiation and beamstrahlung, which can be relevant for higher values of the beam energy are also included in the analysis.

  2. Hyaluronan functionalizing QDs as turn-on fluorescent probe for targeted recognition CD44 receptor

    Science.gov (United States)

    Zhou, Shang; Huo, Danqun; Hou, Changjun; Yang, Mei; Fa, Huanbao

    2017-09-01

    The recognition of tumor markers in living cancer cells has attracted increasing interest. In the present study, the turn-on fluorescence probe was designed based on the fluorescence of thiolated chitosan-coated CdTe QDs (CdTe/TCS QDs) quenched by hyaluronan, which could provide the low background signal for sensitive cellular imaging. This system is expected to offer specific recognition of CD44 receptor over other substances owing to the specific affinity of hyaluronan and CD44 receptor ( 8-9 kcal/mol). The probe is stable in aqueous and has little toxicity to living cells; thus, it can be utilized for targeted cancer cell imaging. The living lung cancer cell imaging experiments further demonstrate its value in recognizing cell-surface CD44 receptor with turn-on mode. In addition, the probe can be used to recognize and differentiate the subtypes of lung cancer cells based on the difference of CD44 expression on the surface of lung cancer cells. And, the western blot test further confirmed that the expression level of the CD44 receptor in lung cancer cells is different. Therefore, this probe may be potentially applied in recognizing lung cancer cells with higher contrast and sensitivity and provide new tools for cancer prognosis and therapy. [Figure not available: see fulltext.

  3. A colorimetric and ratiometric fluorescent probe for sulfite based on an intramolecular cleavage mechanism.

    Science.gov (United States)

    Hou, Peng; Chen, Song; Voitchovsky, Kislon; Song, Xiangzhi

    2014-11-01

    A colorimetric and ratiometric fluorescent sulfite probe, the levulinate of 4-hydroxynaphthalimide, was successfully synthesized from 4-hydroxy-naphthalimide and levulinic acid. Through sulfite-mediated intramolecular cleavage, the probe was converted into 4-hydroxynaphthalimide, which when excited at 450 nm, displayed a large Stokes shift due to the intramolecular charge transfer process. The probe exhibited high selectivity and sensitivity towards sulfite over other typical anionic species (F(-), Cl(-), Br(-), I(-), HPO(4)(2-), SO(4)(2-), NO(3)(-), AcO(-), ClO(4)(-), HCO(3)(-)) in HEPES-buffered solution (25 mm, pH 7.4, 50% acetonitrile, v/v). Copyright © 2013 John Wiley & Sons, Ltd.

  4. Polarized fluorescence measurements of orientational order in a uniaxial liquid crystal

    DEFF Research Database (Denmark)

    Chapoy, L. Lawrence; DuPré, Donald B.

    1979-01-01

    The second and fourth orientational order parameters and , have been measured throughout the liquid crystalline phase of p-methoxybenzylidene-p[prime]-n-butylaniline (MBBA) using small quantities of a fluorescent probe. Complications of rotational Brownian motion and the intramolecular transfer o...... of excitation energy were considered in the analysis. The results are in agreement with previous Raman measurements on the doped liquid crystal. The Journal of Chemical Physics is copyrighted by The American Institute of Physics.......The second and fourth orientational order parameters and , have been measured throughout the liquid crystalline phase of p-methoxybenzylidene-p[prime]-n-butylaniline (MBBA) using small quantities of a fluorescent probe. Complications of rotational Brownian motion and the intramolecular transfer...

  5. A two-photon fluorescent probe with a large turn-on signal for imaging hydrogen sulfide in living tissues

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Kaibo [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China); Lin, Weiying, E-mail: weiyinglin2013@163.com [Institute of Fluorescent Probes for Biological Imaging, University of Jinan, Jinan, Shandong 250022 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China); Tan, Li; Cheng, Dan [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China)

    2015-01-01

    Highlights: • A two-photon fluorescent probe for sensing H{sub 2}S was developed. • The probe shows a large turn on signal (120-fold enhancement). • The probe is suitable for fluorescence imaging of H{sub 2}S in living cells and tissues. • The probe was capable of detecting H{sub 2}S up to 170 μm depth in live tissues. - Abstract: A two-photon fluorescence turn-on H{sub 2}S probe GCTPOC–H{sub 2}S based on a two-photon platform with a large cross-section, GCTPOC, and a sensitive H{sub 2}S recognition site, dinitrophenyl ether was constructed. The probe GCTPOC–H{sub 2}S exhibits desirable properties such as high sensitivity, high selectivity, functioning well at physiological pH and low cytotoxicity. In particular, the probe shows a 120-fold enhancement in the presence of Na{sub 2}S (500 μM), which is larger than the reported two-photon fluorescent H{sub 2}S probes. The large fluorescence enhancement of the two-photon probe GCTPOC–H{sub 2}S renders it attractive for imaging H{sub 2}S in living tissues with deep tissue penetration. Significantly, we have demonstrated that the probe GCTPOC–H{sub 2}S is suitable for fluorescence imaging of H{sub 2}S in living tissues with deep penetration by using two-photon microscopy. The further application of the two-photon probe for the investigation of biological functions and pathological roles of H{sub 2}S in living systems is under progress.

  6. Quantitative generalized ratiometric fluorescence spectroscopy for turbid media based on probe encapsulated by biologically localized embedding

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Xiu-Fang; Chen, Zeng-Ping, E-mail: zpchen2002@hotmail.com; Cui, Yin-Yin; Hu, Yuan-Liang; Yu, Ru-Qin

    2016-05-19

    PEBBLE (probe encapsulated by biologically localized embedding) nanosensor encapsulating an intensity-based fluorescence indicator and an inert reference fluorescence dye inside the pores of stable matrix can be used as a generalized wavelength-ratiometric probe. However, the lack of an efficient quantitative model render the choices of inert reference dyes and intensity-based fluorescence indicators used in PEBBLEs based generalized wavelength-ratiometric probes rather limited. In this contribution, an extended quantitative fluorescence model was derived specifically for generalized wavelength-ratiometric probes based on PEBBLE technique (QFM{sub GRP}) with a view to simplify the design of PEBBLEs and hence further extend their application potentials. The effectiveness of QFM{sub GRP} has been tested on the quantitative determination of free Ca{sup 2+} in both simulated and real turbid media using a Ca{sup 2+} sensitive PEBBLE nanosensor encapsulating Rhod-2 and eosin B inside the micropores of stable polyacrylamide matrix. Experimental results demonstrated that QFM{sub GRP} could realize precise and accurate quantification of free Ca{sup 2+} in turbid samples, even though there is serious overlapping between the fluorescence excitation peaks of eosin B and Ca{sup 2+} bound Rhod-2. The average relative predictive error value of QFM{sub GRP} for the test simulated turbid samples was 5.9%, about 2–4 times lower than the corresponding values of partial least squares calibration model and the empirical ratiometric model based on the ratio of fluorescence intensities at the excitation peaks of Ca{sup 2+} bound Rhod-2 and eosin B. The recovery rates of QFM{sub GRP} for the real and spiked turbid samples varied from 93.1% to 101%, comparable to the corresponding results of atomic absorption spectrometry. - Highlights: • An advanced model was derived for generalized wavelength-ratiometric PEBBLEs. • The model can simplify the design of generalized wavelength

  7. Polarized light scattering as a probe for changes in chromosome structure

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, Daniel Benjamin [Univ. of California, Berkeley, CA (United States)

    1993-10-01

    Measurements and calculations of polarized light scattering are applied to chromosomes. Calculations of the Mueller matrix, which completely describes how the polarization state of light is altered upon scattering, are developed for helical structures related to that of chromosomes. Measurements of the Mueller matrix are presented for octopus sperm heads, and dinoflagellates. Comparisons of theory and experiment are made. A working theory of polarized light scattering from helices is developed. The use of the first Born approximation vs the coupled dipole approximation are investigated. A comparison of continuous, calculated in this work, and discrete models is also discussed. By comparing light scattering measurements with theoretical predictions the average orientation of DNA in an octopus sperm head is determined. Calculations are made for the Mueller matrix of DNA plectonemic helices at UV, visible and X-ray wavelengths. Finally evidence is presented that the chromosomes of dinoflagellates are responsible for observed differential scattering of circularly-polarized light. This differential scattering is found to vary in a manner that is possibly correlated to the cell cycle of the dinoflagellates. It is concluded that by properly choosing the wavelength probe polarized light scattering can provide a useful tool to study chromosome structure.

  8. Highly selective fluorescent probe for the detection of tin (IV) Ion

    International Nuclear Information System (INIS)

    Zhu, Leiming; Yang, Jing; Wang, Qiusheng; Zeng, Lintao

    2014-01-01

    A novel fluorescent compound, 7-diethylamino-3-(2'-(1H-imidazo[4,5-b]phenazine)yl)coumarin (DIPC), was synthesized and employed as a fluorescent probe for detecting tin (IV) ion. Upon addition of tin (IV) ion to the solution of DIPC in DMSO–water (9:1, v/v), DIPC exhibited a considerable red-shift in its absorption spectrum and a decrease in fluorescence intensity. These changes result from tin (IV) ion binding to carbonyl oxygen of coumarin and nitrogen of imidazole, reflecting an enhanced ICT process from N,N-diethylamino unit to imidazole unit. The tin (IV) ion selective response was clearly observed by the naked eye through color change. We also studied the bioimaging application of DIPC for detecting tin (IV) ion in Hela cells. And a significant decrease of the fluorescence from the intracellular area was observed. -- Highlights: • We synthesized a novel coumarin derivative (DIPC). • DIPC was used to detect tin (IV) ion selectively. • The detection process was studied upon UV–vis and fluorescence spectrum. • We studied the bioimaging application of DIPC for detecting Sn 4+ ion in cells

  9. Measurement of fluorescent probes concentration ratio in the cerebrospinal fluid for early detection of Alzheimer's disease

    Science.gov (United States)

    Harbater, Osnat; Gannot, Israel

    2014-03-01

    The pathogenic process of Alzheimer's Disease (AD), characterized by amyloid plaques and neurofibrillary tangles in the brain, begins years before the clinical diagnosis. Here, we suggest a novel method which may detect AD up to nine years earlier than current exams, minimally invasive, with minimal risk, pain and side effects. The method is based on previous reports which relate the concentrations of biomarkers in the Cerebrospinal Fluid (CSF) (Aβ and Tau proteins) to the future development of AD in mild cognitive impairment patients. Our method, which uses fluorescence measurements of the relative concentrations of the CSF biomarkers, replaces the lumbar puncture process required for CSF drawing. The process uses a miniature needle coupled trough an optical fiber to a laser source and a detector. The laser radiation excites fluorescent probes which were prior injected and bond to the CSF biomarkers. Using the ratio between the fluorescence intensities emitted from the two biomarkers, which is correlated to their concentration ratio, the patient's risk of developing AD is estimated. A theoretical model was developed and validated using Monte Carlo simulations, demonstrating the relation between fluorescence emission and biomarker concentration. The method was tested using multi-layered tissue phantoms simulating the epidural fat, the CSF in the sub-arachnoid space and the bone. These phantoms were prepared with different scattering and absorption coefficients, thicknesses and fluorescence concentrations in order to simulate variations in human anatomy and in the needle location. The theoretical and in-vitro results are compared and the method's accuracy is discussed.

  10. Determination of ATP as a fluorescence probe with europium(III)-doxycycline.

    Science.gov (United States)

    Hou, Faju; Wang, Xiaolei; Jiang, Chongqiu

    2005-03-01

    A new spectrofluorimetric method has been developed for the determination of adenosine disodium triphosphate (ATP). We studied the interactions between the doxycycline (DC)-Eu3+ complex and adenosine disodium triphosphate (ATP) by using UV-visible absorption and fluorescence spectra. Using doxycycline (DC)-Eu3+ as a fluorescence probe, under the optimum conditions, ATP could remarkably enhance the fluorescence intensity of the DC-Eu3+ complex at lambda = 612 nm. The enhanced fluorescence intensity of the Eu3+ ion was in proportion to the concentration of ATP. The optimum conditions for the determination of ATP were also investigated. The linear ranges for ATP were 1.00 x 10(-7) - 2.00 x 10(-6) mol L(-1) with detection limits of 4.07 x 10(-8) mol L(-1). This method is simple, practical and relatively free of interference from coexisting substances, and can be successfully applied to the determination of ATP in samples. The mechanism of fluorescence enhancement between the doxycycline (DC)-Eu3+ complex and ATP was also studied.

  11. Determination of adenosine disodium triphosphate using prulifloxacin-terbium(III) as a fluorescence probe by spectrofluorimetry

    International Nuclear Information System (INIS)

    Yu Fengshan; Li Lin; Chen Fang

    2008-01-01

    A new spectrofluorimetric method is developed for determination of adenosine disodium triphosphate (ATP). The interactions between prulifloxacin (PUFX)-Tb 3+ complex and adenosine disodium triphosphate has been studied by using UV-vis absorption and fluorescence spectra. Using prulifloxacin-Tb 3+ as a fluorescence probe, under the optimum conditions, ATP can remarkably enhance the fluorescence intensity of the prulifloxacin-Tb 3+ complex at λ = 545 nm and the enhanced fluorescence intensity is in proportion to the concentration of ATP. Optimum conditions for the determination of ATP were also investigated. The dynamic range for the determination of ATP is 4.0 x 10 -7 to 2.0 x 10 -5 mol L -1 , and the detection limit (3 σ/k) is 1.7 x 10 -8 mol L -1 . This method is simple, practical and relatively free interference from coexisting substances and can be successfully applied to determination of ATP in real pharmaceutical samples. The mechanism of fluorescence enhancement of prulifloxacin-Tb 3+ complex by ATP was also discussed

  12. Fluorescent peptide biosensor for probing the relative abundance of cyclin-dependent kinases in living cells.

    Directory of Open Access Journals (Sweden)

    Laetitia Kurzawa

    Full Text Available Cyclin-dependant kinases play a central role in coordinating cell growth and division, and in sustaining proliferation of cancer cells, thereby constituting attractive pharmacological targets. However, there are no direct means of assessing their relative abundance in living cells, current approaches being limited to antigenic and proteomic analysis of fixed cells. In order to probe the relative abundance of these kinases directly in living cells, we have developed a fluorescent peptide biosensor with biligand affinity for CDKs and cyclins in vitro, that retains endogenous CDK/cyclin complexes from cell extracts, and that bears an environmentally-sensitive probe, whose fluorescence increases in a sensitive fashion upon recognition of its targets. CDKSENS was introduced into living cells, through complexation with the cell-penetrating carrier CADY2 and applied to assess the relative abundance of CDK/Cyclins through fluorescence imaging and ratiometric quantification. This peptide biosensor technology affords direct and sensitive readout of CDK/cyclin complex levels, and reports on differences in complex formation when tampering with a single CDK or cyclin. CDKSENS further allows for detection of differences between different healthy and cancer cell lines, thereby enabling to distinguish cells that express high levels of these heterodimeric kinases, from cells that present decreased or defective assemblies. This fluorescent biosensor technology provides information on the overall status of CDK/Cyclin complexes which cannot be obtained through antigenic detection of individual subunits, in a non-invasive fashion which does not require cell fixation or extraction procedures. As such it provides promising perspectives for monitoring the response to therapeutics that affect CDK/Cyclin abundance, for cell-based drug discovery strategies and fluorescence-based cancer diagnostics.

  13. Photophysics of Fluorescent Probes for Single-Molecule Biophysics and Super-Resolution Imaging

    Science.gov (United States)

    Ha, Taekjip; Tinnefeld, Philip

    2012-05-01

    Single-molecule fluorescence spectroscopy and super-resolution microscopy are important elements of the ongoing technical revolution to reveal biochemical and cellular processes in unprecedented clarity and precision. Demands placed on the photophysical properties of the fluorophores are stringent and drive the choice of appropriate probes. Such fluorophores are not simple light bulbs of a certain color and brightness but instead have their own “personalities” regarding spectroscopic parameters, redox properties, size, water solubility, photostability, and several other factors. Here, we review the photophysics of fluorescent probes, both organic fluorophores and fluorescent proteins, used in applications such as particle tracking, single-molecule FRET, stoichiometry determination, and super-resolution imaging. Of particular interest is the thiol-induced blinking of Cy5, a curse for single-molecule biophysical studies that was later overcome using Trolox through a reducing/oxidizing system but a boon for super-resolution imaging owing to the controllable photoswitching. Understanding photophysics is critical in the design and interpretation of single-molecule experiments.

  14. Calix[2]pyreno[2]pyrrole as a Fluorescence Chemical Probe for Polynitroaromatics

    International Nuclear Information System (INIS)

    Park, Kyung Hwa; Yoo, Jae Duk; Lee, Chang Hee; Ka, Jae Won

    2012-01-01

    We have demonstrated that the new, readily synthesized and well characterized calix pyreno pyrrole fluorescence molecular probe can detect polynitroaromatic compounds with high affinity. In addition, this highly fluorescent neutral molecular receptor also exhibits enhanced binding affinity towards TNT which is associated with the formation of a pi-complex. The dynamic nature of the current system may enable it to serve as an excellent scaffold for electron-deficient guest molecular binding. Studies for other neutral molecules including metal ions are under in active progress. The elevated selectivity and sensitivity for specific analytes are the core requirements for an ideal chemical probes. A signal induced by guest binding must be sensitive enough so that accurate real time monitoring could be satisfactorily achieved. Introduction of signaling units at suitable places in which they can directly interact with the recognition events is critical in designing chemosensors. Among various signaling events, fluorescence changes are often applied for the sensitive detection of various analytes. An easy modulation of the photochemical properties of the signaling units is an additional advantage in compatibility and applications. Chemosensors for the detection of explosives becomes important due to their immediate applications in remedation of explosive manufacturing sites, homeland security or forensic sciences. With that in mind, numerous methods for the explosive detection have been reported in recent years. Nevertheless, some detection methods sometimes require sophisticated instrumentation which is not easy for on-site testing

  15. A quick response fluorescent probe based on coumarin and quinone for glutathione and its application in living cells

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Xi [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Du, Zhi-Fang [Taishan College, Shandong University, Jinan 250100 (China); Wang, Li-Hong; Miao, Jun-Ying [Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100 (China); Zhao, Bao-Xiang, E-mail: bxzhao@sdu.edu.cn [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2016-05-30

    We have designed and synthesized a simple but effective fluorescent probe for sensing glutathione (GSH) by PET process based on coumarin and quinone, which worked as fluorophore and reaction site, respectively. The probe could discriminate GSH from cysteine and homocysteine within 1 min in PBS-buffered solution. The sensing mechanism was confirmed by density functional theory (DFT), viscosity test, fluorescence spectrum analysis and HRMS, respectively. The probe has a low limit of detection (0.1 μM) and finally been used in cell imaging successfully. - Highlights: • This probe can discriminate glutathione from sulfhydryl compound by PET process. • This probe can be used to determine glutathione in aqueous solution within 1 min. • This probe has been successfully applied in living cell image.

  16. A quick response fluorescent probe based on coumarin and quinone for glutathione and its application in living cells

    International Nuclear Information System (INIS)

    Dai, Xi; Du, Zhi-Fang; Wang, Li-Hong; Miao, Jun-Ying; Zhao, Bao-Xiang

    2016-01-01

    We have designed and synthesized a simple but effective fluorescent probe for sensing glutathione (GSH) by PET process based on coumarin and quinone, which worked as fluorophore and reaction site, respectively. The probe could discriminate GSH from cysteine and homocysteine within 1 min in PBS-buffered solution. The sensing mechanism was confirmed by density functional theory (DFT), viscosity test, fluorescence spectrum analysis and HRMS, respectively. The probe has a low limit of detection (0.1 μM) and finally been used in cell imaging successfully. - Highlights: • This probe can discriminate glutathione from sulfhydryl compound by PET process. • This probe can be used to determine glutathione in aqueous solution within 1 min. • This probe has been successfully applied in living cell image.

  17. A novel fluorescent probe that senses the physical state of lipid bilayers.

    Science.gov (United States)

    Sasaki, Hirotaka; White, Stephen H

    2009-06-03

    Cell membrane lipids and proteins are heterogeneously distributed in the membrane plane. In recent years, much attention has been paid to the heterogeneous distribution of the lipid components, particularly the formation of cholesterol-rich domains that are thought to be important in signaling processes. This has led to renewed interest in the phase diagrams of complex lipid mixtures, such as three-component mixtures containing phospholipids and cholesterol. We report here a novel fluorescent probe (NBD-R595) that is useful for exploring the phase behaviors of one-, two-, and three-component large unilamellar vesicles. In one-component fluid-phase membranes, the probe has the expected spectral characteristic of monomeric 7-nitrobenzo-2-oxa-1,3-diazol, with a fluorescence maximum of 540 nm when excited at 470 nm. But below the gel-to-liquid crystalline phase transition temperature, an additional emission peak appears at approximately 610 nm, because of Förster resonance energy transfer from NBD-R595 monomers to NBD-R595 Jelley aggregates of limited size formed by the association of 7-nitrobenzo-2-oxa-1,3-diazol moieties. This may be the first report of Förster resonance energy transfer from a single fluorophore in two different physical states. In a test of the probe, we found NBD-R595 to be remarkably sensitive to the molar composition of large unilamellar vesicles formed from cholesterol, distearoylphosphatidylcholine, and dioleoylphosphatidylcholine.

  18. Deciphering the binding behaviours of BSA using ionic AIE-active fluorescent probes.

    Science.gov (United States)

    Tong, Jiaqi; Hu, Ting; Qin, Anjun; Sun, Jing Zhi; Tang, Ben Zhong

    2017-02-01

    The binding behaviours of a transport protein, bovine serum albumin (BSA), in its native, unfolding and refolding states have been probed by monitoring the emission changes of two exogenous AIE-active fluorescent probes, M2 and M3, which are designed to be anionic and cationic, respectively. Due to their AIE properties, both M2 and M3 display emission enhancement when bound to the hydrophobic cavity of BSA. The binding site of M2 and M3 is found to be subdomain IIA. Then, the BSA + M2 and BSA + M3 systems are utilized to fluorescently signal the conformation changes of BSA caused by various external stimuli, including thermally or chemically induced denaturation. The data confirmed the multi-step unfolding process and the existence of a molten-globule intermediate state. The unfolding process consists of the rearrangement of subdomain IIA, the exposure of a negatively charged binding site in domain I that prefers interacting with cationic species, and the transformation of the molten-globule intermediate into the final random coil. The anionic and cationic modifications of the probes enable us to observe that electrostatic interactions play a role in the folding and unfolding of BSA.

  19. Cellular Activation of the Self-Quenched Fluorescent Reporter Probe in Tumor Microenvironment

    Directory of Open Access Journals (Sweden)

    Alexei A. Bogdanov, Jr.

    2002-01-01

    Full Text Available The effect of intralysosomal proteolysis of near-infrared fluorescent (NIRF self-quenched macromolecular probe (PGC-Cy5.5 has been previously reported and used for tumor imaging. Here we demonstrate that proteolysis can be detected noninvasively in vivo at the cellular level. A codetection of GFP fluorescence (using two-photon excitation and NIRF was performed in tumor-bearing animals injected with PGC-Cy5.5. In vivo microscopy of tumor cells in subdermal tissue layers (up to 160 μm showed a strong Cy5.5 dequenching effect in GFP-negative cells. This observation was corroborated by flow cytometry, sorting, and reverse transcription polymerase chain reaction analysis of tumor-isolated cells. Both GFP-positive (81% total and GFP-negative (19% total populations contained Cy5.5-positive cells. The GFP-negative cells were confirmed to be host mouse cells by the absence of rat cathepsin mRNA signal. The subfraction of GFPnegative cells (2.5-3.0% had seven times higher NIRF intensity than the majority of GFP-positive or GFPnegative cells (372 and 55 AU, respectively. Highly NIRF-positive, FP-negative cells were CD45-and MAC3-positive. Our results indicate that: 1 intracellular proteolysis can be imaged in vivo at the cellular level using cathepsin-sensitive probes; 2 tumor-recruited cells of hematopoetic origin participate most actively in uptake and degradation of long-circulating macromolecular probes.

  20. Diversity oriented fluorescence library approach (DOFLA) for live cell imaging probe development.

    Science.gov (United States)

    Yun, Seong-Wook; Kang, Nam-Young; Park, Sung-Jin; Ha, Hyung-Ho; Kim, Yun Kyung; Lee, Jun-Seok; Chang, Young-Tae

    2014-04-15

    A cell is the smallest functional unit of life. All forms of life rely on cellular processes to maintain normal functions, and changes in cell function induced by metabolic disturbances, physicochemical damage, infection, or abnormal gene expression may cause disease. To understand basic biology and to develop therapeutics for diseases, researchers need to study live cells. Along with advances in fluorescence microscopy and in vitro cell culture, live-cell imaging has become an essential tool in modern biology for the study of molecular and cellular events. Although researchers have often used fluorescent proteins to visualize cell-type-specific markers, this method requires genetic manipulations, which may not be appropriate in nontransgenic cells. Immunodetection of cellular markers requires the use of xenogenic antibodies, which may not detect intracellular markers in live cells. One option for overcoming these problems is the use of fluorescent small molecules targeted to specific cell types, which can enter live cells and interact with molecules of interest. We have used combinatorial chemistry to develop a large number of fluorescent small molecules as new imaging probes even without prior information about the probes' binding targets and mechanism, a strategy that we call the diversity oriented fluorescence library approach (DOFLA). We have used DOFLA to produce novel sensors and probes that detect a variety of biological and chemical molecules in vivo as well as in vitro. In this Account, we describe a series of fluorescent small molecules developed using DOFLA that bind specifically to particular cell types. These molecules provide new ways to detect and isolate these cells. The fluorescent probes CDy1, CDg4, and CDb8 tag embryonic stem cells and induced pluripotent stem cells but not fibroblasts or germ-line cells. CDr3 binds to an intracellular neural stem cell marker, fatty acid binding protein 7, which allows researchers to separate neural stem cells

  1. Probing the graphite band structure with resonant soft-x-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Carlisle, J.A.; Shirley, E.L.; Hudson, E.A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Soft x-ray fluorescence (SXF) spectroscopy using synchrotron radiation offers several advantages over surface sensitive spectroscopies for probing the electronic structure of complex multi-elemental materials. Due to the long mean free path of photons in solids ({approximately}1000 {angstrom}), SXF is a bulk-sensitive probe. Also, since core levels are involved in absorption and emission, SXF is both element- and angular-momentum-selective. SXF measures the local partial density of states (DOS) projected onto each constituent element of the material. The chief limitation of SXF has been the low fluorescence yield for photon emission, particularly for light elements. However, third generation light sources, such as the Advanced Light Source (ALS), offer the high brightness that makes high-resolution SXF experiments practical. In the following the authors utilize this high brightness to demonstrate the capability of SXF to probe the band structure of a polycrystalline sample. In SXF, a valence emission spectrum results from transitions from valence band states to the core hole produced by the incident photons. In the non-resonant energy regime, the excitation energy is far above the core binding energy, and the absorption and emission events are uncoupled. The fluorescence spectrum resembles emission spectra acquired using energetic electrons, and is insensitive to the incident photon`s energy. In the resonant excitation energy regime, core electrons are excited by photons to unoccupied states just above the Fermi level (EF). The absorption and emission events are coupled, and this coupling manifests itself in several ways, depending in part on the localization of the empty electronic states in the material. Here the authors report spectral measurements from highly oriented pyrolytic graphite.

  2. Smart lanthanide coordination polymer fluorescence probe for mercury(II) determination

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Baoxia [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); Huang, Yankai [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhu, Xu; Hao, Yuanqiang [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); Ding, Yujie [College of Biochemical Engineering, Anhui Polytechnic University, Wuhu 241000 (China); Wei, Wei; Wang, Qi [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); Qu, Peng, E-mail: qupeng0212@163.com [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Xu, Maotian, E-mail: xumaotian@sqnc.edu.cn [Henan Key Laboratory Cultivation Base of Nanobiological Analytical Chemistry, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000 (China); College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China)

    2016-03-17

    Lanthanide coordination polymers (LCPs) have recently emerged as attractive biosensor materials due to their flexible components, high tailorable properties and unique luminescence features. In this work, we designed a smart LCP probe of Tb-CIP/AMP {(CIP, ciprofloxacin) (AMP, adenosine monophosphate)} for Hg{sup 2+} detection by using lanthanide ions as metal nodes, CIP as ligand molecule, and AMP as bridging linker and recognition unit. Tb-CIP/AMP emits strong green luminescence due to the inclusion of AMP, which withdraws the coordinated water molecules and shields Tb{sup 3+} from the quenching effect of O–H vibration in water molecules. The subsequent addition of Hg{sup 2+} into Tb-CIP/AMP can strongly quench the fluorescence because of the specific coordination interaction between AMP and Hg{sup 2+}. As a kind of Hg{sup 2+} nanosensor, the probe exhibited excellent selectivity for Hg{sup 2+} and high sensitivity with detection limit of 0.16 nM. In addition, the probe has long fluorescence lifetime up to millisecond and has been applied to detect Hg{sup 2+} in drinking water and human urine samples with satisfactory results. We envision that our strategy, in the future, could be extended to the designation of other LCP-based hypersensitive time-gated luminescence assays in biological media and biomedical imaging. - Highlights: • Lanthanide coordination polymer of Tb-CIP/AMP was synthesized via a simple self-assembly process. • AMP was employed as a bifunctional molecule for both fluorescence sensitization and target recognition. • Hypersensitive detection of Hg{sup 2+} was achieved based on time-resolved spectroscopy.

  3. Smart lanthanide coordination polymer fluorescence probe for mercury(II) determination

    International Nuclear Information System (INIS)

    Liu, Baoxia; Huang, Yankai; Zhu, Xu; Hao, Yuanqiang; Ding, Yujie; Wei, Wei; Wang, Qi; Qu, Peng; Xu, Maotian

    2016-01-01

    Lanthanide coordination polymers (LCPs) have recently emerged as attractive biosensor materials due to their flexible components, high tailorable properties and unique luminescence features. In this work, we designed a smart LCP probe of Tb-CIP/AMP {(CIP, ciprofloxacin) (AMP, adenosine monophosphate)} for Hg 2+ detection by using lanthanide ions as metal nodes, CIP as ligand molecule, and AMP as bridging linker and recognition unit. Tb-CIP/AMP emits strong green luminescence due to the inclusion of AMP, which withdraws the coordinated water molecules and shields Tb 3+ from the quenching effect of O–H vibration in water molecules. The subsequent addition of Hg 2+ into Tb-CIP/AMP can strongly quench the fluorescence because of the specific coordination interaction between AMP and Hg 2+ . As a kind of Hg 2+ nanosensor, the probe exhibited excellent selectivity for Hg 2+ and high sensitivity with detection limit of 0.16 nM. In addition, the probe has long fluorescence lifetime up to millisecond and has been applied to detect Hg 2+ in drinking water and human urine samples with satisfactory results. We envision that our strategy, in the future, could be extended to the designation of other LCP-based hypersensitive time-gated luminescence assays in biological media and biomedical imaging. - Highlights: • Lanthanide coordination polymer of Tb-CIP/AMP was synthesized via a simple self-assembly process. • AMP was employed as a bifunctional molecule for both fluorescence sensitization and target recognition. • Hypersensitive detection of Hg 2+ was achieved based on time-resolved spectroscopy.

  4. Low energy spin polarized radioactive beams as a probe of thin films and interfaces

    CERN Document Server

    Kiefl, R F; Amaudruz, P A; Arseneau, D; Baartman, R; Beals, T R; Behr, J; Brewer, J; Daviel, S; Hatakeyama, A; Hitti, B; Kreitzman, S R; Levy, C D P; Miller, R; Olivo, M; Poutissou, R; Morris, G D; Dunsiger, S R; Heffner, R; Chow, K H; Hirayama, Y; Izumi, H; Bommas, C; Dumont, E; Greene, L H

    2003-01-01

    A spectrometer for beta-detected nuclear magnetic resonance (beta-NMR) has been commissioned at the ISAC facility at TRIUMF. A beam of low energy highly spin polarized sup 8 Li sup + can be decelerated and implanted into ultra-thin structures 6-400 nm thick. beta-NMR provides local information on the electronic and magnetic properties of materials which is similar to conventional NMR but can be used as a sensitive probe of ultra-thin films, interfaces and other nanostructures. We report here on the status of the spectrometer and preliminary results on a simple metal film.

  5. Polarization entanglement of sum-frequency photons: A tool to probe the Markovian limit

    Science.gov (United States)

    Volkov, Victor; Chelli, Riccardo

    2015-06-01

    The article addresses the possibility of entanglement-specific infrared-visible sum-frequency generation spectroscopy. In the case of an anisotropic interface, it is possible to employ SSS and PSS polarizations to detect responses not only specific to χY Y Y and χX Y Y nonlinearities, but also to higher-order χ(Y Y Y )(X Y Y ) and χ(X Y Y )(Y Y Y ) nonlinearities. Using quantum mechanical studies of the rhenium complex [Re (OH) 3(CO) 3] as a molecular model, we demonstrate that if such complexes would form an anisotropic orientational distribution at a surface, under the considered geometry and the polarization settings, we may prepare quantum correlated C =O vibrational states to emit polarization-entangled photons. Accordingly, we explore the possibility of a polarization-measurement protocol to extract spectral signatures of the entangled states. The response would be informative on intramolecular interactions. As a result, we discuss the possible practical implications in probing dynamics at interfaces, and different opportunities in the preparation of entangled vibrational states of quantified fidelity.

  6. Metal-organic framework based highly selective fluorescence turn-on probe for hydrogen sulphide

    Science.gov (United States)

    Nagarkar, Sanjog S.; Saha, Tanmoy; Desai, Aamod V.; Talukdar, Pinaki; Ghosh, Sujit K.

    2014-11-01

    Hydrogen sulphide (H2S) is known to play a vital role in human physiology and pathology which stimulated interest in understanding complex behaviour of H2S. Discerning the pathways of H2S production and its mode of action is still a challenge owing to its volatile and reactive nature. Herein we report azide functionalized metal-organic framework (MOF) as a selective turn-on fluorescent probe for H2S detection. The MOF shows highly selective and fast response towards H2S even in presence of other relevant biomolecules. Low cytotoxicity and H2S detection in live cells, demonstrate the potential of MOF towards monitoring H2S chemistry in biological system. To the best of our knowledge this is the first example of MOF that exhibit fast and highly selective fluorescence turn-on response towards H2S under physiological conditions.

  7. A turn-on fluorescent probe for endogenous formaldehyde in the endoplasmic reticulum of living cells

    Science.gov (United States)

    Tang, Yonghe; Ma, Yanyan; Xu, An; Xu, Gaoping; Lin, Weiying

    2017-06-01

    As the simplest aldehyde compounds, formaldehyde (FA) is implicated in nervous system diseases and cancer. Endoplasmic reticulum is an organelle that plays important functions in living cells. Accordingly, the development of efficient methods for FA detection in the endoplasmic reticulum (ER) is of great biomedical importance. In this work, we developed the first ER-targeted fluorescent FA probe Na-FA-ER. The detection is based on the condensation reaction of the hydrazine group and FA to suppress the photo-induced electron transfer (PET) pathway, resulting in a fluorescence increase. The novel Na-FA-ER showed high sensitivity to FA. In addition, the Na-FA-ER enabled the bio-imaging of exogenous and endogenous FA in living HeLa cells. Most significantly, the new Na-FA-ER was employed to visualize the endogenous FA in the ER in living cells for the first time.

  8. Phosphorus doped graphitic carbon nitride nanosheets as fluorescence probe for the detection of baicalein.

    Science.gov (United States)

    Wang, Xuan; Li, Xuebing; Chen, Wenfang; Wang, Rulin; Bian, Wei; Choi, Martin M F

    2018-02-24

    Phosphorus doped graphitic carbon nitride (P-g-C 3 N 4 ) nanosheets were synthesized by calcination. P-g-C 3 N 4 nanosheets were characterized by XRD, XPS, TEM, fluorescence, ultraviolet-visible absorption and Fourier transform infrared spectroscopy. The fluorescence of the P-g-C 3 N 4 nanosheets was gradually quenched with the increase in the concentration of baicalein at room temperature. The proposed probe was used for the determination of baicalein in the concentration 2.0-30μM with a detection limit of 53nM. The quenching mechanism was discussed. The P-g-C 3 N 4 nanosheets have been successfully applied for effective and selective detection of baicalein in human urine samples and blood samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Quantum-chemical investigations of spectroscopic properties of a fluorescence probe

    Science.gov (United States)

    Titova, T. Yu.; Morozova, Yu. P.; Zharkova, O. M.; Artyukhov, V. Ya.; Korolev, B. V.

    2012-09-01

    The prodan molecule (6-propionyl-2-dimethylamino naphthalene) - fluorescence probe - is investigated by quantum-chemical methods of intermediate neglect of differential overlap (INDO) and molecular electrostatic potential (MEP). The dipole moments of the ground and excited states, the nature and position of energy levels, the centers of specific solvation, the rate constants of photoprocesses, and the fluorescence quantum yield are estimated. To elucidate the role of the dimethylamino group in the formation of bands and spectral characteristics, the molecule only with the propionyl group (pron) is investigated. The long-wavelength absorption bands of prodan and pron molecules are interpreted. The results obtained for the prodan molecule by the INDO method with original spectroscopic parameterization are compared with the literature data obtained by the DFT/CIS, ZINDO/S, and AM1/CISD methods.

  10. A benzothiazole-based fluorescent probe for distinguishing and bioimaging of Hg{sup 2+} and Cu{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Biao; Huang, Liyan; Su, Wei; Duan, Xiaoli; Li, Haitao, E-mail: haitao-li@hunnu.edu.cn; Yao, Shouzhuo

    2017-02-15

    A new benzothiazole-based fluorescent probe 2-(benzo[d]thiazol-2-yl)-4-(1,3- dithian-2-yl)phenol (BT) with two different reaction sites, a thioacetal group (site 1 for Hg{sup 2+}), and O and N atoms of the benzothiazole dye (site 2 for Cu{sup 2+}), was designed and synthesized. The probe BT showed ratiometric fluorescent response to Hg{sup 2+} and fluorescence quenching behavior to Cu{sup 2+}, which induces naked-eye fluorescent color changes from green to blue and colorless, respectively. Moreover, it displayed highly sensitivity and selectivity toward Hg{sup 2+} and Cu{sup 2+} without interference from other metal ions. The sensing mechanisms were also confirmed by {sup 1}H NMR titration, mass spectrum and Job's plot analyses. Finally, probe BT was successfully used for fluorescent imaging of Hg{sup 2+} and Cu{sup 2+} in living cells, demonstrating its potential applications in biological science. - Highlights: • A benzothiazole-based probe for multiple metal ions has been firstly developed. • The differential sensing mechanisms of Hg{sup 2+} and Cu{sup 2+} relied on different reaction. • The probe could be used to monitor Hg{sup 2+} and Cu{sup 2+}in vitro and in vivo with distinct fluorescence changes.

  11. Detection of 13,19-didesmethyl C spirolide by fluorescence polarization using Torpedo electrocyte membranes.

    Science.gov (United States)

    Fonfría, Eva S; Vilariño, Natalia; Molgó, Jordi; Aráoz, Rómulo; Otero, Paz; Espiña, Begoña; Louzao, M Carmen; Alvarez, Mercedes; Botana, Luis M

    2010-08-01

    Fluorescence polarization (FP) is a powerful tool for studying molecular interactions by monitoring changes in the apparent size of fluorescent molecules. In this paper, a previously described fluorescence polarization assay was used to detect 13,19-didesmethyl C spirolide. The assay is based on the competition of cyclic imine marine biotoxins with alpha-bungarotoxin for binding to nicotinic acetylcholine receptor-enriched membranes of Torpedo marmorata. The 13,19-didesmethyl C spirolide was detected in buffer and mussel matrix. The sensitivity of the assay for the 13,19-didesmethyl C spirolide and the 13-desmethyl C spirolide was similar. After an acetone/chloroform extraction of spiked mussel meat, the average recovery rate of 13,19-didesmethyl C spirolide was 77.7 +/- 1.9%. The quantification range for this toxin in mussel was 40-200 microg/kg of shellfish meat. This assay can be used to detect the spirolides 13,19-didesmethyl C spirolide and 13-desmethyl C spirolide, in shellfish as a screening assay. Copyright 2010 Elsevier Inc. All rights reserved.

  12. In situ probing of intracellular pH by fluorescence from inorganic nanoparticles.

    Science.gov (United States)

    Guo, Junhong; Xiong, Shijie; Wu, Xinglong; Shen, Jiancang; Chu, Paul K

    2013-12-01

    Intracellular pH (pHi) plays a critical role in the physiological processes of cells. Nanoscale sensors based on pH-sensitive fluorescent proteins attached on nanoparticles (NPs) have been designed but inorganic NP-dependent fluorescent nanosensors have not yet been explored. Herein we describe a pH sensitive inorganic semiconductor fluorescent probe based on ultrathin 3C-SiC NPs which can effectively monitor pH in the range of 5.6-7.4 by taking advantage of the linear dependence between the fluorescent intensity ratio of the surface OH(-) and H(+) bonding states to band-to-band recombination and pH. Detection of pHi is demonstrated in living HeLa cells. In particular, pHi measurements during apoptosis confirm the validity and sensitivity of this technique in monitoring real-time changes in the intracellular environment. Toxicity assessment and confocal laser scanning microscopy indicate that the 3C-SiC NPs have low cytotoxicity and are compatible with living cells. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Fluorescence probe of polypeptide conformational dynamics in gas phase and in solution

    Science.gov (United States)

    Iavarone, Anthony T.; Meinen, Jan; Schulze, Susanne; Parks, Joel H.

    2006-07-01

    Fluorescence measurements of polypeptides derivatized with the fluorescent dye BODIPY TMR have been used to probe the polypeptide conformational dynamics as a function of temperature and charge state. Measurements of (BODIPY TMR)-[Pro]n-Arg-Trp and (BODIPY TMR)-[Gly-Ser]m-Arg-Trp have been performed for charge states 1+ and 2+ of n = 4 and 10 and m = 2 and 5. The 2+ charge states of both of these polypeptides exhibit similar temperature dependences for equal chain lengths (n = 4, m = 2 and n = 10, m = 5) and suggest conformations dominated by Coulomb repulsion. In the absence of such Coulomb repulsion, the 1+ charge state conformations appear to be characterized by the flexibility of the polypeptide chain for which [Gly-Ser]m > [Pro]n. Comparisons of these gas phase polypeptide measurements with corresponding measurements in solution provide a direct measure of the effects of solvent on the conformational dynamics. The change in fluorescence as a function of temperature in the gas phase is two orders of magnitude greater than that in solution, a dramatic result we attribute to the restrictions on intramolecular dynamics imposed by diffusion-limited kinetics and the lack of shielding by solvent. Measurements were also made of unsolvated Pron peptides without the tryptophan (Trp) residue to isolate the interaction of the fluorescent dye with charges.

  14. Diffusion behaviors of fluorescence probe molecules through the stratum corneum layer under physical stress.

    Science.gov (United States)

    Lee, Ho; Kim, Jin Woong

    2013-04-01

    This study experimentally demonstrates how application of an external physical stress onto the skin membrane affects the permeation of penetrating molecules. As a proxy of active compounds, in this study, a series of fluorescence probe molecules were utilized. We observed that skin permeation could be enhanced by imparting vertical strokes from a tapping head consisting of projections onto the skin. This was confirmed with consistency from in vitro and in vivo transdermal permeation studies. After an effective physical stress was applied to the skin, the permeation depth of probe molecules remarkably increased, which was comparable to the case of topical treatment. This seems to arise from temporal disordering of the stratum corneum layer in response to the applied physical stress.

  15. Near-infrared fluorescent probes for imaging of amyloid plaques in Alzheimer׳s disease.

    Science.gov (United States)

    Tong, Hongjuan; Lou, Kaiyan; Wang, Wei

    2015-01-01

    One of the early pathological hallmarks of Alzheimer׳s disease (AD) is the deposition of amyloid-β (Aβ) plaques in the brain. There has been a tremendous interest in the development of Aβ plaques imaging probes for early diagnosis of AD in the past decades. Optical imaging, particularly near-infrared fluorescence (NIRF) imaging, has emerged as a safe, low cost, real-time, and widely available technique, providing an attractive approach for in vivo detection of Aβ plaques among many different imaging techniques. In this review, we provide a brief overview of the state-of-the-art development of NIRF Aβ probes and their in vitro and in vivo applications with special focus on design strategies and optical, binding, and brain-kinetic properties.

  16. Mechanochromic Fluorescent Probe Molecules for Damage Detection in Aerospace Polymers and Composites

    Science.gov (United States)

    Toivola, Ryan E.

    The detection of damage in aerospace composites can be improved by incorporation of mechanochromic fluorescent probe molecules into the polymers used in composite parts. This study focuses on a novel series of mechanochromic probes, AJNDE15 and AJNDE17, which are incorporated in structural epoxy resin DGEBA-DETA. Chapter 1 details the characterization of the DGEBA-DETA epoxy system used in this study. The important characteristics of DGEBA-DETA's response to mechanical loading will be discussed within the larger field of glassy amorphous polymer deformation. The mechanical, thermal, and chemical properties of DGEBA-DETA relevant to this work will be measured using standardized techniques and instrumentation. Chapters 2 and 3 focus on the mechanochromic probes AJNDE15 and AJNDE17 in the DGEBA-DETA system. Chapter 2 presents research designed to identify the mechanism through which the probes display mechanochromism. The possible mechanochromic mechanisms are introduced in a literature review. Research on these probes in DGEBA-DETA will be presented and discussed with respect to the possible mechanisms, and the mechanism that best fits the results will be identified as a mechanochemical reaction. Chapter 3 continues the analysis of the mechanochromism of the probes in DGEBA-DETA. The kinetics of the mechanochromic reaction will be studied and compared with the current understanding of glassy polymer deformation. Possible models for the molecular interactions responsible for mechanochromism in this system will be put forward. Research will be presented to evaluate the mechanochromism kinetics and for comparison with the behavior predicted by the models.

  17. Method for Imaging Live-Cell RNA Using an RNA Aptamer and a Fluorescent Probe.

    Science.gov (United States)

    Sato, Shin-Ichi; Yatsuzuka, Kenji; Katsuda, Yousuke; Uesugi, Motonari

    2018-01-01

    Live-cell imaging of mRNA dynamics is increasingly important to understanding spatially restricted gene expression. We recently developed a convenient and versatile method that uses a gene-specific RNA aptamer and a fluorescent probe to enable spatiotemporal imaging of endogenous mRNAs in living cells. The method was validated by live-cell imaging of the endogenous mRNA of β-actin. The new RNA-imaging technology might be useful for live-cell imaging of any RNA molecules.

  18. Pentamethinium fluorescent probes: The impact of molecular structure on photophysical properties and subcellular localization

    Czech Academy of Sciences Publication Activity Database

    Bříza, T.; Rimpelová, S.; Králová, Jarmila; Záruba, K.; Kejík, Z.; Ruml, T.; Martásek, P.; Král, V.

    2014-01-01

    Roč. 107, August 2014 (2014), s. 51-59 ISSN 0143-7208 R&D Projects: GA AV ČR KAN200100801; GA ČR(CZ) GAP303/11/1291; GA MŠk(CZ) CZ.01.05/2.1.00/01.00.30; GA MŠk(CZ) CZ.1.07/2.300/30.0060 Institutional support: RVO:68378050 Keywords : Pentamethinium salts * Fluorescent probes * Mitochondria * Cardiolipin Photostability * Organelle imaging Subject RIV: CE - Biochemistry Impact factor: 3.966, year: 2014

  19. The tandem Mannich-electrophilic amination reaction: a versatile platform for fluorescent probing and labeling.

    Science.gov (United States)

    Sączewski, Jarosław; Hinc, Krzysztof; Obuchowski, Michał; Gdaniec, Maria

    2013-08-26

    Tandem fluorogenic reaction: A new platform for the direct, selective and sensitive detection of formaldehyde and/or secondary aliphatic amines, based on a tandem Mannich-electrophilic amination reaction, is described. Biological applications of hydrophilic, water-soluble fluorescent 2,2-dialkyl-2,3-dihydro-[1,2,4]triazolo[4,3-a]pyridin-2-ium-8-carboxylates (Safarinium P probes) are exemplified by labeling of the amine-containing Ac-AKF-NH2 peptide and Bacillus subtilis spores in aqueous solution. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Synthesis of improved upconversion nanoparticles as ultrasensitive fluorescence probe for mycotoxins

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Quansheng, E-mail: q.s.chen@hotmail.com; Hu, Weiwei; Sun, Cuicui; Li, Huanhuan; Ouyang, Qin

    2016-09-28

    Rare earth-doped upconversion nanoparticles (UCNPs) have promising potentials in biodetection due to their unique frequency upconverting capability and high detection sensitivity. This paper reports an improved UCNPs-based fluorescence probe for dual-sensing of Aflatoxin B1 (AFB1) and Deoxynivalenol (DON) using a magnetism-induced separation and the specific formation of antibody-targets complex. Herein, the improved UCNPs, which were namely NaYF{sub 4}:Yb/Ho/Gd and NaYF{sub 4}:Yb/Tm/Gd, were systematically studied based on the optimization of reaction time, temperature and the concentration of dopant ions with simultaneous phase and size controlled NaYF{sub 4} nanoparticles; and the targets were detected using the pattern of competitive combination assay. Under an optimized condition, the advanced fluorescent probes revealed stronger fluorescent properties, broader biological applications and better storage stabilities compared to traditional UCNPs-based ones; and ultrasensitive determinations of AFB1 and DON were achieved under a wide sensing range of 0.001–0.1 ng ml{sup −1} with the limit of detection (LOD) of 0.001 ng ml{sup −1}. Additionally, the applicability of the improved nanosensor for the detection of mycotoxins was also confirmed in adulterated oil samples. - Highlights: • Improved rare earth-doped upconversion nanoparticles were prepared with detailed optimizations. • Setup of an upconversion fluorescence spectrometer. • An advanced UCNPs-based immunosensor for dual-sensing mycotoxins was developed with a LOD of 0.001 ng ml{sup −1}. • Application of this biosensor to detect targets in real samples were confirmed with satisfied results.

  1. In vivo imaging of alkaline phosphatase in tumor-bearing mouse model by a promising near-infrared fluorescent probe.

    Science.gov (United States)

    Liu, Hong-Wen; Hu, Xiao-Xiao; Zhu, Longmin; Li, Ke; Rong, Qiming; Yuan, Lin; Zhang, Xiao-Bing; Tan, Weihong

    2017-12-01

    Alkaline phosphatase (ALP), one of the important hydrolases, is associated with the progress of many diseases as a well-defined biomarker. Fluorescence imaging of ALP in living organisms is of great importance for biological studies. However, in vivo detection of ALP remains a great challenge because current fluorescent probes show short excitation and emission wavelength, which are not desired for in vivo fluorescence imaging. Herein we reported a near-infrared (NIR) fluorescent probe (NALP) for turn-on trapping of ALP activity in living cancer cells and tumors. NALP was composed of a NIR-emitting fluorophore as a reporter and phosphate as a triggered moiety. Phosphate group was directly tethered to the hydroxyl group of fluorophore, which prohibited the fluorescence. The probe exhibited a high selectivity and remarkable fluorescence turn-on response to ALP in aqueous solutions with a detection limit of 0.28U/L. Benefiting from NIR excitation and emission, high contrast on the imaging signal could be achieved in response to endogenous ALP activity. Impressively, not only we successfully used NALP for imaging of endogenous ALP activity in cancer cells, but also, applied it for fluorescence imaging of ALP in tumor tissues and living tumor xenograft in nude mice for the first time. The probe was expected to be promising tool for practical application in disease diagnosis on the roles of ALP in disease. Copyright © 2017. Published by Elsevier B.V.

  2. A rate-equation model for polarized laser-induced fluorescence to measure electric field in glow discharge He plasmas

    International Nuclear Information System (INIS)

    Takiyama, K.; Watanabe, M.; Oda, T.

    1998-01-01

    Possibility of applying polarized laser-induced fluorescence (LIF) spectroscopy for measuring the electric field in a plasma with a large collisional depolarization has been investigated. A rate equation model including the depolarization process was employed to analyze the time evolution of LIF polarization components. The polarized LIF pulse shapes observed in the sheath of a He glow discharge plasma were successfully reproduced, and the electric field distribution was obtained with high accuracy. (author)

  3. Far-red fluorescent probes for canonical and non-canonical nucleic acid structures: current progress and future implications.

    Science.gov (United States)

    Suseela, Y V; Narayanaswamy, Nagarjun; Pratihar, Sumon; Govindaraju, Thimmaiah

    2018-02-05

    The structural diversity and functional relevance of nucleic acids (NAs), mainly deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are indispensable for almost all living organisms, with minute aberrations in their structure and function becoming causative factors in numerous human diseases. The standard structures of NAs, termed canonical structures, are supported by Watson-Crick hydrogen bonding. Under special physiological conditions, NAs adopt distinct spatial organisations, giving rise to non-canonical conformations supported by hydrogen bonding other than the Watson-Crick type; such non-canonical structures have a definite function in controlling gene expression and are considered as novel diagnostic and therapeutic targets. Development of molecular probes for these canonical and non-canonical DNA/RNA structures has been an active field of research. Among the numerous probes studied, probes with turn-on fluorescence in the far-red (600-750 nm) region are highly sought-after due to minimal autofluorescence and cellular damage. Far-red fluorescent probes are vital for real-time imaging of NAs in live cells as they provide good resolution and minimal perturbation of the cell under investigation. In this review, we present recent advances in the area of far-red fluorescent probes of DNA/RNA and non-canonical G-quadruplex structures. For the sake of continuity and completeness, we provide a brief overview of visible fluorescent probes. Utmost importance is given to design criteria, characteristic properties and biological applications, including in cellulo imaging, apart from critical discussion on limitations of the far-red fluorescent probes. Finally, we offer current and future prospects in targeting canonical and non-canonical NAs specific to cellular organelles, through sequence- and conformation-specific far-red fluorescent probes. We also cover their implications in chemical and molecular biology, with particular focus on decoding various disease

  4. NitroxylFluor: A Thiol-Based Fluorescent Probe for Live-Cell Imaging of Nitroxyl.

    Science.gov (United States)

    Pino, Nicholas W; Davis, Jerome; Yu, Zhengxin; Chan, Jefferson

    2017-12-27

    Detection of nitroxyl (HNO), the transient one-electron reduced form of nitric oxide, is a significant challenge owing to its high reactivity with biological thiols (with rate constants as high as 10 9  M -1 s -1 ). To address this, we report a new thiol-based HNO-responsive trigger that can compete against reactive thiols for HNO. This process forms a common N-hydroxysulfenamide intermediate that cyclizes to release a masked fluorophore leading to fluorescence enhancement. To ensure that the cyclization step is rapid, our design capitalizes on two established physical organic phenomena; the alpha-effect and the Thorpe-Ingold effect. Using this new trigger, we developed NitroxylFluor, a selective HNO-responsive fluorescent probe. Treatment of NitroxylFluor with an HNO donor results in a 16-fold turn-on. This probe also exhibits excellent selectivity over various reactive nitrogen, oxygen, and sulfur species and efficacy in the presence of thiols (e.g., glutathione in mM concentrations). Lastly, we successfully performed live cell imaging of HNO using NitroxylFluor.

  5. Quantifying Aflatoxin B1 in peanut oil using fabricating fluorescence probes based on upconversion nanoparticles

    Science.gov (United States)

    Sun, Cuicui; Li, Huanhuan; Koidis, Anastasios; Chen, Quansheng

    2016-08-01

    Rare earth doped upconversion nanoparticles convert near-infrared excitation light into visible emission light. Compared to organic fluorophores and semiconducting nanoparticles, upconversion nanoparticles (UCNPs) offer high photochemical stability, sharp emission bandwidths, and large anti-Stokes shifts. Along with the significant light penetration depth and the absence of autofluorescence in biological samples under infrared excitation, these UCNPs have attracted more and more attention on toxin detection and biological labelling. Herein, the fluorescence probe based on UCNPs was developed for quantifying Aflatoxin B1 (AFB1) in peanut oil. Based on a specific immunity format, the detection limit for AFB1 under optimal conditions was obtained as low as 0.2 ng·ml- 1, and in the effective detection range 0.2 to 100 ng·ml- 1, good relationship between fluorescence intensity and AFB1 concentration was achieved under the linear ratios up to 0.90. Moreover, to check the feasibility of these probes on AFB1 measurements in peanut oil, recovery tests have been carried out. A good accuracy rating (93.8%) was obtained in this study. Results showed that the nanoparticles can be successfully applied for sensing AFB1 in peanut oil.

  6. Folic acid-targeted magnetic Tb-doped CeF3 fluorescent nanoparticles as bimodal probes for cellular fluorescence and magnetic resonance imaging.

    Science.gov (United States)

    Ma, Zhi-Ya; Liu, Yu-Ping; Bai, Ling-Yu; An, Jie; Zhang, Lin; Xuan, Yang; Zhang, Xiao-Shuai; Zhao, Yuan-Di

    2015-10-07

    Magnetic fluorescent nanoparticles (NPs) have great potential applications for diagnostics, imaging and therapy. We developed a facile polyol method to synthesize multifunctional Fe3O4@CeF3:Tb@CeF3 NPs with small size (imaging agents for simultaneous in vitro targeted fluorescence imaging and magnetic resonance imaging (MRI) of HeLa cells with overexpressed folate receptors (FR). The results indicated that these NPs had strong luminescence and enhanced T2-weighted MR contrast and would be promising candidates as multimodal probes for both fluorescence and MRI imaging.

  7. Rhodol-based far-red fluorescent probe for the detection of cysteine and homocysteine over glutathione.

    Science.gov (United States)

    Liu, Yunchang; Xiang, Kaiqiang; Tian, Baozhu; Zhang, Jinlong

    2017-02-01

    The simultaneous discrimination of cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) is of great importance due to their roles in biology and close link to many diseases, especially via the development of a far-red fluorescent probe that could be used for rapid, selective, and sensitive detection of all three. Herein, we report the characterization of a far-red fluorescent probe with turn-on fluorescence properties and visible color changes that could be used for the detection of cysteine and homocysteine over glutathione. In this study we found that the sensor could discriminate cysteine and homocysteine over glutathione within 20 min. Function of this probe was based on the conjugate addition-cyclization reaction and showed a low detection limit to cysteine and homocysteine. Upon the addition of cysteine and homocysteine, the absorption band at 592 nm rose gradually and fluorescence was detected at 645 nm. The color changed from colorless to blue and fluorescence changed from absent to strong red fluorescence, which could be differentiated by the naked eye. All these unique features make this probe particularly potentially favorable for use in cysteine/homocysteine sensing and bioimaging applications. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. A fluorescent paramagnetic Mn metal–organic framework based on semi-rigid pyrene tetracarboxylic acid: sensing of solvent polarity and explosive nitroaromatics

    Directory of Open Access Journals (Sweden)

    Alankriti Bajpai

    2015-09-01

    Full Text Available An Mn metal–organic framework (Mn-MOF, Mn-L, based on a pyrene-tetraacid linker (H4L, displays a respectable fluorescence quantum yield of 8.3% in spite of the presence of the paramagnetic metal ions, due presumably to fixation of the metal ions in geometries that do not allow complete energy/charge-transfer quenching. Remarkably, the porous Mn-L MOF with ∼25% solvent-accessible volume exhibits a heretofore unprecedented solvent-dependent fluorescence emission maximum, permitting its use as a probe of solvent polarity; the emission maxima in different solvents correlate excellently with Reichardt's solvent polarity parameter (ETN. Further, the applicability of Mn-L to the sensing of nitroaromatics via fluorescence quenching is demonstrated; the detection limit for TNT is shown to be 125 p.p.m. The results bring out the fact that MOFs based on paramagnetic metal ions can indeed find application when the quenching mechanisms are attenuated by certain geometries of the organic linkers of the MOF.

  9. Modulation of dual fluorescence in a 3-hydroxyquinolone dye by perturbation of its intramolecular proton transfer with solvent polarity and basicity.

    Science.gov (United States)

    Yushchenko, Dmytro A; Shvadchak, Volodymyr V; Bilokin', Mykhailo D; Klymchenko, Andrey S; Duportail, Guy; Mély, Yves; Pivovarenko, Vasyl G

    2006-11-01

    A representative of a new class of dyes with dual fluorescence due to an excited state intramolecular proton transfer (ESIPT) reaction, namely 1-methyl-2-(4-methoxy)phenyl-3-hydroxy-4(1H)-quinolone (QMOM), has been studied in a series of solvents covering a large range of polarity and basicity. A linear dependence of the logarithm of its two bands intensity ratio, log(I(N*)/I(T*)), upon the solvent polarity expressed as a function of the dielectric constant, (epsilon- 1)/(2epsilon + 1), is observed for a series of protic solvents. A linear dependence for log(I(N*)/I(T*)) is also found in aprotic solvents after taking into account the solvent basicity. In contrast, the positions of the absorption and the two emission bands of QMOM do not noticeably depend on the solvent polarity and basicity, indicating relatively small changes in the transition moment of QMOM upon excitation and emission. Time-resolved experiments in acetonitrile, ethyl acetate and dimethylformamide suggest an irreversible ESIPT reaction for this dye. According to the time-resolved data, an increase of solvent basicity results in a dramatic decrease of the ESIPT rate constant, probably due to the disruption of the intramolecular H-bond of the dye by the basic solvent. Due to this new sensor property, 3-hydroxyquinolones are promising candidates for the development of a new generation of environment-sensitive fluorescence dyes for probing interactions of biomolecules.

  10. Fluorescent Nano-Probes to Image Plant Cell Walls by Super-Resolution STED Microscopy.

    Science.gov (United States)

    Paës, Gabriel; Habrant, Anouck; Terryn, Christine

    2018-02-06

    Lignocellulosic biomass is a complex network of polymers making up the cell walls of plants. It represents a feedstock of sustainable resources to be converted into fuels, chemicals, and materials. Because of its complex architecture, lignocellulose is a recalcitrant material that requires some pretreatments and several types of catalysts to be transformed efficiently. Gaining more knowledge in the architecture of plant cell walls is therefore important to understand and optimize transformation processes. For the first time, super-resolution imaging of poplar wood samples has been performed using the Stimulated Emission Depletion (STED) technique. In comparison to standard confocal images, STED reveals new details in cell wall structure, allowing the identification of secondary walls and middle lamella with fine details, while keeping open the possibility to perform topochemistry by the use of relevant fluorescent nano-probes. In particular, the deconvolution of STED images increases the signal-to-noise ratio so that images become very well defined. The obtained results show that the STED super-resolution technique can be easily implemented by using cheap commercial fluorescent rhodamine-PEG nano-probes which outline the architecture of plant cell walls due to their interaction with lignin. Moreover, the sample preparation only requires easily-prepared plant sections of a few tens of micrometers, in addition to an easily-implemented post-treatment of images. Overall, the STED super-resolution technique in combination with a variety of nano-probes can provide a new vision of plant cell wall imaging by filling in the gap between classical photon microscopy and electron microscopy.

  11. Fluorescent Nano-Probes to Image Plant Cell Walls by Super-Resolution STED Microscopy

    Directory of Open Access Journals (Sweden)

    Gabriel Paës

    2018-02-01

    Full Text Available Lignocellulosic biomass is a complex network of polymers making up the cell walls of plants. It represents a feedstock of sustainable resources to be converted into fuels, chemicals, and materials. Because of its complex architecture, lignocellulose is a recalcitrant material that requires some pretreatments and several types of catalysts to be transformed efficiently. Gaining more knowledge in the architecture of plant cell walls is therefore important to understand and optimize transformation processes. For the first time, super-resolution imaging of poplar wood samples has been performed using the Stimulated Emission Depletion (STED technique. In comparison to standard confocal images, STED reveals new details in cell wall structure, allowing the identification of secondary walls and middle lamella with fine details, while keeping open the possibility to perform topochemistry by the use of relevant fluorescent nano-probes. In particular, the deconvolution of STED images increases the signal-to-noise ratio so that images become very well defined. The obtained results show that the STED super-resolution technique can be easily implemented by using cheap commercial fluorescent rhodamine-PEG nano-probes which outline the architecture of plant cell walls due to their interaction with lignin. Moreover, the sample preparation only requires easily-prepared plant sections of a few tens of micrometers, in addition to an easily-implemented post-treatment of images. Overall, the STED super-resolution technique in combination with a variety of nano-probes can provide a new vision of plant cell wall imaging by filling in the gap between classical photon microscopy and electron microscopy.

  12. Probing GFP-actin diffusion in living cells using fluorescence correlation spectroscopy

    International Nuclear Information System (INIS)

    Engelke, Hanna; Heinrich, Doris; Rädler, Joachim O.

    2010-01-01

    The cytoskeleton of eukaryotic cells is continuously remodeled by polymerization and depolymerization of actin. Consequently, the relative content of polymerized filamentous actin (F-actin) and monomeric globular actin (G-actin) is subject to temporal and spatial fluctuations. Since fluorescence correlation spectroscopy (FCS) can measure the diffusion of fluorescently labeled actin it seems likely that FCS allows us to determine the dynamics and hence indirectly the structural properties of the cytoskeleton components with high spatial resolution. To this end we investigate the FCS signal of GFP-actin in living Dictyostelium discoideum cells and explore the inherent spatial and temporal signatures of the actin cytoskeleton. Using the free green fluorescent protein (GFP) as a reference, we find that actin diffusion inside cells is dominated by G-actin and slower than diffusion in diluted cell extract. The FCS signal in the dense cortical F-actin network near the cell membrane is probed using the cytoskeleton protein LIM and is found to be slower than cytosolic G-actin diffusion. Furthermore, we show that polymerization of the cytoskeleton induced by Jasplakinolide leads to a substantial decrease of G-actin diffusion. Pronounced fluctuations in the distribution of the FCS correlation curves can be induced by latrunculin, which is known to induce actin waves. Our work suggests that the FCS signal of GFP-actin in combination with scanning or spatial correlation techniques yield valuable information about the local dynamics and concomitant cytoskeletal properties

  13. Direct fluorescence in situ hybridization on human metaphase chromosomes using quantum dot-platinum labeled DNA probes

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Gyoyeon [Chemical Kinomics Research Center, Future Convergence Research Division, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Biological Chemistry, Korea University of Science and Technology, 217, Gajeong-ro, Yuseong-gu, Deajeon (Korea, Republic of); Lee, Hansol [Chemical Kinomics Research Center, Future Convergence Research Division, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Lee, Jiyeon, E-mail: jylee@kist.re.kr [Chemical Kinomics Research Center, Future Convergence Research Division, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Biological Chemistry, Korea University of Science and Technology, 217, Gajeong-ro, Yuseong-gu, Deajeon (Korea, Republic of)

    2015-11-13

    The telomere shortening in chromosomes implies the senescence, apoptosis, or oncogenic transformation of cells. Since detecting telomeres in aging and diseases like cancer, is important, the direct detection of telomeres has been a very useful biomarker. We propose a telomere detection method using a newly synthesized quantum dot (QD) based probe with oligonucleotide conjugation and direct fluorescence in situ hybridization (FISH). QD-oligonucleotides were prepared with metal coordination bonding based on platinum-guanine binding reported in our previous work. The QD-oligonucleotide conjugation method has an advantage where any sequence containing guanine at the end can be easily bound to the starting QD-Pt conjugate. A synthesized telomeric oligonucleotide was bound to the QD-Pt conjugate successfully and this probe hybridized specifically on the telomere of fabricated MV-4-11 and MOLT-4 chromosomes. Additionally, the QD-telomeric oligonucleotide probe successfully detected the telomeres on the CGH metaphase slide. Due to the excellent photostability and high quantum yield of QDs, the QD-oligonucleotide probe has high fluorescence intensity when compared to the organic dye-oligonucleotide probe. Our QD-oligonucleotide probe, conjugation method of this QD probe, and hybridization protocol with the chromosomes can be a useful tool for chromosome painting and FISH. - Highlights: • We prepared a probe linked between QD and telomeric oligonucleotide with platinum-guanine bonding. • Telomeres were detected by our new telomere probes successfully in three different human metaphase chromosomes. • QDPt-DNA probe has high fluorescence intensity in comparison with organic dye-DNA probe.

  14. Negligible water surface charge determined using Kelvin probe and total reflection X-ray fluorescence techniques.

    Science.gov (United States)

    Shapovalov, Vladimir L; Möhwald, Helmuth; Konovalov, Oleg V; Knecht, Volker

    2013-09-07

    The water surface charge has been extensively debated in recent decades. Electrophoretic mobilities of air bubbles in water and disjoining pressures between the surfaces of aqueous films suggest that the surface of water exhibits a significant negative charge. This is commonly attributed to a strong adsorption of hydroxide ions at the interface, though spectroscopic measurements and simulation studies suggest surface depletion of hydroxide ions. Alternatively, the negative surface charge could arise from surface contamination with trace charged surfactants. We have probed the variation in the surface charge of water with pH by measuring surface potentials using the Kelvin probe technique. Independently, the abundance in the interfacial layer of "reporter ions" (Rb(+) and Br(-)), which must be affected by a charged surface, has been monitored using the total reflection X-ray fluorescence (TRXF) technique. Special care was taken to prove the high sensitivity of this technique as well as to avoid surface contaminants. The magnitude of the surface charge was found to be below 1 e per 500 nm(2) (TRXF). No evidence of variations in the surface potential between pH 2-3 and pH 9-12 was detected within the accuracies of the methods (5 mV for Kelvin probe and 2 mV for TRXF). Hence, our findings suggest that the clean water surface exhibits negligible charge in a wide pH range.

  15. Identification of adiponectin receptor agonist utilizing a fluorescence polarization based high throughput assay.

    Directory of Open Access Journals (Sweden)

    Yiyi Sun

    Full Text Available Adiponectin, the adipose-derived hormone, plays an important role in the suppression of metabolic disorders that can result in type 2 diabetes, obesity, and atherosclerosis. It has been shown that up-regulation of adiponectin or adiponectin receptor has a number of therapeutic benefits. Given that it is hard to convert the full size adiponectin protein into a viable drug, adiponectin receptor agonists could be designed or identified using high-throughput screening. Here, we report on the development of a two-step screening process to identify adiponectin agonists. First step, we developed a high throughput screening assay based on fluorescence polarization to identify adiponectin ligands. The fluorescence polarization assay reported here could be adapted to screening against larger small molecular compound libraries. A natural product library containing 10,000 compounds was screened and 9 hits were selected for validation. These compounds have been taken for the second-step in vitro tests to confirm their agonistic activity. The most active adiponectin receptor 1 agonists are matairesinol, arctiin, (--arctigenin and gramine. The most active adiponectin receptor 2 agonists are parthenolide, taxifoliol, deoxyschizandrin, and syringin. These compounds may be useful drug candidates for hypoadiponectin related diseases.

  16. Nitroolefin-based BODIPY as a novel water-soluble ratiometric fluorescent probe for detection of endogenous thiols

    Science.gov (United States)

    Kang, Jin; Huo, Fangjun; Chao, Jianbin; Yin, Caixia

    2018-04-01

    Small molecule biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play many crucial roles in physiological processes. In this work, we have prepared a nitroolefin-based BODIPY fluorescent probe with excellent water solubility for detection thiols, which displayed ratiometric fluorescent signal for thiols. Incorporation of a nitroolefin unit to the BODIPY dye would transform it into a strong Michael acceptor, which would be highly susceptible to sulfhydryl nucleophiles. This probe shows an obvious ratio change upon response with thiols, an increase of the emission at 517 nm along with a concomitant decrease of fluorescence peak at 573 nm. Moreover, these successes of intracellular imaging experiments in A549 cells indicated that this probe is suitable for imaging of ex-/endogenous thiols in living cells.

  17. A novel NBD-based fluorescent turn-on probe for the detection of cysteine and homocysteine in living cells

    Science.gov (United States)

    Wang, Jiamin; Niu, Linqiang; Huang, Jing; Yan, Zhijie; Wang, Jianhong

    2018-03-01

    Biothiols, such as cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), are involved in a number of biological processes and play crucial roles in biological systems. Thus, the detection of biothiols is highly important for early diagnosis of diseases and evaluation of disease progression. Herein, we developed a new turn-on fluorescent probe 1 based on 7-nitro-2,1,3-benzoxadiazole (NBD) with high selectivity and sensitivity for Cys/Hcy on account of nucleophilic substitution and Smiles rearrangement reaction. The probe could sense Cys/Hcy rapidly, the intensity of fluorescence increased immediately within 1 min. Furthermore, the probe is low toxic and has been successfully applied to detect intracellular Cys/Hcy by cell fluorescence imaging in living normal and cancer cells.

  18. Communication: angular momentum alignment and fluorescence polarization of alkali atoms photodetached from helium nanodroplets.

    Science.gov (United States)

    Hernando, Alberto; Beswick, J Alberto; Halberstadt, Nadine

    2013-12-14

    The theory of photofragments angular momentum polarization is applied to the photodetachment of an electronically excited alkali atom from a helium nanocluster (N = 200). The alignment of the electronic angular momentum of the bare excited alkali atoms produced is calculated quantum mechanically by solving the excited states coupled equations with potentials determined by density functional theory (DFT). Pronounced oscillations as a function of excitation energy are predicted for the case of Na@(He)200, in marked contrast with the absorption cross-section and angular distribution of the ejected atoms which are smooth functions of the energy. These oscillations are due to quantum interference between different coherently excited photodetachment pathways. Experimentally, these oscillations should be reflected in the fluorescence polarization and polarization-resolved photoelectron yield of the ejected atoms, which are proportional to the electronic angular momentum alignment. In addition, this result is much more general than the test case of NaHe200 studied here. It should be observable for larger droplets, for higher excited electronic states, and for other alkali as well as for alkali-earth atoms. Detection of these oscillations would show that the widely used pseudo-diatomic model can be valid beyond the prediction of absorption spectra and could help in interpreting parts of the dynamics, as already hinted by some experimental results on angular anisotropy of bare alkali fragments.

  19. Modelling and experimental verification of tip-induced polarization in Kelvin probe force microscopy measurements on dielectric surfaces

    DEFF Research Database (Denmark)

    Nielsen, Dennis Achton; Popok, Vladimir; Pedersen, Kjeld

    2015-01-01

    Kelvin probe force microscopy is a widely used technique for measuring surface potential distributions on the micro- and nanometer scale. The data are, however, often analyzed qualitatively, especially for dielectrics. In many cases, the phenomenon of polarization and its influence on the measured...... signals is disregarded leading to misinterpretation of the results. In this work, we present a model that allows prediction of the surface potential on a metal/polymer heterostructure as measured by Kelvin probe force microscopy by including the tip-induced polarization of the dielectric that arises...

  20. Organic Liquids-Responsive β-Cyclodextrin-Functionalized Graphene-Based Fluorescence Probe: Label-Free Selective Detection of Tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Huawen Hu

    2014-06-01

    Full Text Available In this study, a label-free graphene-based fluorescence probe used for detection of volatile organic liquids was fabricated by a simple, efficient and low-cost method. To fabricate the probe, a bio-based β-cyclodextrin (β-CD was firstly grafted on reduced graphene surfaces effectively and uniformly, as evidenced by various characterization techniques such as Ultraviolet/Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The subsequent inclusion of Rhodamine B (RhB into the inner cavities of the β-CD grafted on the graphene surfaces was achieved easily by a solution mixing method, which yielded the graphene-based fluorescent switch-on probe. In addition, the gradual and controllable quenching of RhB by Fluorescence Resonance Energy Transfer from RhB to graphene during the process of stepwise accommodation of the RhB molecules into the β-CD-functionalized graphene was investigated in depth. A wide range of organic solvents was examined using the as-fabricated fluorescence probe, which revealed the highest sensitivity to tetrahydrofuran with the detection limit of about 1.7 μg/mL. Some insight into the mechanism of the different responsive behaviors of the fluorescence sensor to the examined targets was also described.

  1. Selective and Sensitive Detection of Cyanide Based on the Displacement Strategy Using a Water-Soluble Fluorescent Probe

    Science.gov (United States)

    La, Ming; Hao, Yuanqiang; Wang, Zhaoyang; Han, Guo-Cheng; Qu, Lingbo

    2016-01-01

    A water-soluble fluorescent probe (C-GGH) was used for the highly sensitive and selective detection of cyanide (CN−) in aqueous media based on the displacement strategy. Due to the presence of the recognition unit GGH (Gly-Gly-His), the probe C-GGH can coordinate with Cu2+ and consequently display ON-OFF type fluorescence response. Furthermore, the in situ formed nonfluorescent C-GGH-Cu2+ complex can act as an effective OFF-ON type fluorescent probe for sensing CN− anion. Due to the strong binding affinity of CN− to Cu2+, CN− can extract Cu2+ from C-GGH-Cu2+ complex, leading to the release of C-GGH and the recovery of fluorescent emission of the system. The probe C-GGH-Cu2+ allowed detection of CN− in aqueous solution with a LOD (limit of detection) of 0.017 μmol/L which is much lower than the maximum contaminant level (1.9 μmol/L) for CN− in drinking water set by the WHO (World Health Organization). The probe also displayed excellent specificity for CN− towards other anions, including F−, Cl−, Br−, I−, SCN−, PO4 3−, N3 −, NO3 −, AcO−, SO4 2−, and CO3 2−. PMID:26881185

  2. Selective and Sensitive Detection of Cyanide Based on the Displacement Strategy Using a Water-Soluble Fluorescent Probe

    Directory of Open Access Journals (Sweden)

    Ming La

    2016-01-01

    Full Text Available A water-soluble fluorescent probe (C-GGH was used for the highly sensitive and selective detection of cyanide (CN− in aqueous media based on the displacement strategy. Due to the presence of the recognition unit GGH (Gly-Gly-His, the probe C-GGH can coordinate with Cu2+ and consequently display ON-OFF type fluorescence response. Furthermore, the in situ formed nonfluorescent C-GGH-Cu2+ complex can act as an effective OFF-ON type fluorescent probe for sensing CN− anion. Due to the strong binding affinity of CN− to Cu2+, CN− can extract Cu2+ from C-GGH-Cu2+ complex, leading to the release of C-GGH and the recovery of fluorescent emission of the system. The probe C-GGH-Cu2+ allowed detection of CN− in aqueous solution with a LOD (limit of detection of 0.017 μmol/L which is much lower than the maximum contaminant level (1.9 μmol/L for CN− in drinking water set by the WHO (World Health Organization. The probe also displayed excellent specificity for CN− towards other anions, including F−, Cl−, Br−, I−, SCN−, PO43-, N3-, NO3-, AcO−, SO42-, and CO32-.

  3. In vivo near-infrared fluorescence imaging of amyloid-β plaques with a dicyanoisophorone-based probe

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jia-ying; Zhou, Lin-fu; Li, Yu-kun [School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006 (China); Chen, Shuo-bin [School of Pharmaceutical Science, Sun Yat-sen University, Guangzhou, 510006 (China); Yan, Jin-wu, E-mail: yjw@scut.edu.cn [School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006 (China); Zhang, Lei, E-mail: lzhangce@scut.edu.cn [School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006 (China)

    2017-04-08

    A dicyanoisophorone-based probe with two-photon absorption and NIR emission was developed for the in vivo fluorescence imaging of amyloid-β plaques, which exhibited high selectivity toward Aβ aggregates over other intracellular proteins. The detection limit was calculated to be as low as 109 nM. In vivo imaging studies indicated that the probe could penetrate the blood–brain barrier and label Aβ plaques in the living transgenic mice, and its specific binding to cerebral Aβ plaques was further confirmed by one- and two-photon ex vivo fluorescence imaging. All these results featured its promising application prospects for amyloid-β sensing in basic research and biomedical research. - Highlights: • A two-photon probe (DCIP-1) with NIR emission based on dicyanoisophorone group, for the in vivo fluorescence imaging of amyloid-β plaques, was reported. • The probe showed turn-on fluorescence (13-fold) with a large Stokes shift upon inserting into the hydrophobic pockets of Aβ aggregates. • The in vivo imaging studies indicated that the probe can penetrate the blood–brain barrier efficiently and discriminate APP/PS1 transgenic mice from WT controls.

  4. Spin-polarized scanning-tunneling probe for helical Luttinger liquids.

    Science.gov (United States)

    Das, Sourin; Rao, Sumathi

    2011-06-10

    We propose a three-terminal spin-polarized STM setup for probing the helical nature of the Luttinger liquid edge state that appears in the quantum spin Hall system. We show that the three-terminal tunneling conductance depends on the angle (θ) between the magnetization direction of the tip and the local orientation of the electron spin on the edge while the two terminal conductance is independent of this angle. We demonstrate that chiral injection of an electron into the helical Luttinger liquid (when θ is zero or π) is associated with fractionalization of the spin of the injected electron in addition to the fractionalization of its charge. We also point out a spin current amplification effect induced by the spin fractionalization.

  5. Spectroscopic quantification of 5-hydroxymethylcytosine in genomic DNA using boric acid-functionalized nano-microsphere fluorescent probes.

    Science.gov (United States)

    Chen, Hua-Yan; Wei, Jing-Ru; Pan, Jiong-Xiu; Zhang, Wei; Dang, Fu-Quan; Zhang, Zhi-Qi; Zhang, Jing

    2017-05-15

    5-hydroxymethylcytosine (5hmC) is the sixth base of DNA. It is involved in active DNA demethylation and can be a marker of diseases such as cancer. In this study, we developed a simple and sensitive 2-(4-boronophenyl)quinoline-4-carboxylic acid modified poly (glycidyl methacrylate (PBAQA-PGMA) fluorescent probe to detect the 5hmC content of genomic DNA based on T4 β-glucosyltransferase-catalyzed glucosylation of 5hmC. The fluorescence-enhanced intensity recorded from the DNA sample was proportional to its 5-hydroxymethylcytosine content and could be quantified by fluorescence spectrophotometry. The developed probe showed good detection sensitivity and selectivity and a good linear relationship between the fluorescence intensity and the concentration of 5 hmC within a 0-100nM range. Compared with other fluorescence detection methods, this method not only could determine trace amounts of 5 hmC from genomic DNA but also could eliminate the interference of fluorescent dyes and the need for purification. It also could avoid multiple labeling. Because the PBAQA-PGMA probe could enrich the content of glycosyl-5-hydroxymethyl-2-deoxycytidine from a complex ground substance, it will broaden the linear detection range and improve sensitivity. The limit of detection was calculated to be 0.167nM after enrichment. Furthermore, the method was successfully used to detect 5-hydroxymethylcytosine from mouse tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. A G-quadruplex based fluorescent oligonucleotide turn-on probe towards iodides detection in real samples.

    Science.gov (United States)

    Li, Qian; Li, Shuaihua; Chen, Xiu; Bian, Liujiao

    2017-09-01

    A basket-type G-quadruplex (GQ) fluorescent oligonucleotide (OND) probe is designed to detect iodides dependent on thymine-Hg(II)-thymine (T-Hg(II)-T) base pairs and the intrinsic fluorescence quenching capacity of GQ. In the presence of Hg(II) ions (Hg 2+ ), the two hexachloro-fluorescein-labeled ONDs form a hairpin structure and the fluorophores are dragged close to the GQ, leading to fluorescence quenching of the probe due to photoinduced electron transfer. Upon addition of iodide anions, Hg 2+ are extracted from T-Hg(II)-T complexes which attributes to the stronger binding with iodide anions, resulting in the fluorescence recovery. Through performing the fluorescence quenching and recovery processes, this probe developed a fluorescence turn-on sensor for iodide anions determination over a linear range of 20-200nmol/L with a limit of detection of 5nmol/L. The practical use of the turn-on technology was demonstrated by its application in determination of iodides in water, food, pharmaceutical products and biological samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. A quinoline-based Cu2 + ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells

    Science.gov (United States)

    Dai, Yanpeng; Wang, Peng; Fu, Jiaxin; Yao, Kun; Xu, Kuoxi; Pang, Xiaobin

    2017-08-01

    A quinaldine functionalized probe QP has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu2 + ion over most of the biologically important ions at physiological pH. The binding ratio of the probe QP and Cu2 + ion was determined to be 1:1 through fluorescence titration, Job's plot and ESI-MS. The binding constant (K) of Cu2 + to probe QP was found to be 2.12 × 104 M- 1. Further, the Cu2 + ensemble of probe QP was found to respond H2PO4- and HPO42 - among other important biological anions via fluorescence turn-on response at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe QP could be used as an effective fluorescent probe for detecting Cu2 + cation and H2PO4- and HPO42 - anions in living cells.

  8. Detection of chloroform in water using an azo dye-modified β-cyclodextrin - Epichlorohydrin copolymer as a fluorescent probe

    Science.gov (United States)

    Ncube, Phendukani; Krause, Rui W. M.; Mamba, Bhekie B.

    Chlorination disinfection by-products (DBPs) in water pose a health threat to humans and the aquatic environment. Their detection in water sources is therefore vital. Herein we present the detection of chloroform, a DBP, using a molecular fluorescent probe. The detection was based on the quenching of fluorescence of the probe by chloroform due to host-guest complex formation between β-cyclodextrin in the probe and the chloroform molecule. The stability constant for the host-guest complex was high at 3.825 × 104 M-1. Chloroform quenched the fluorescence of the copolymer the most compared to the other small chlorinated compounds studied, suggesting that the probe was more sensitive to chloroform, with a sensing factor of 0.35 compared to as low as 0.0073 for dichloromethane. There was no interference from other chloroalkanes on the quenching efficiency of chloroform. The probe was used to detect chloroform in dam water as well as in bottled water. Detection of chloroform in both water samples using the probe was possible without chemically treating the water samples which may introduce other pollutants.

  9. A NBD-based simple but effective fluorescent pH probe for imaging of lysosomes in living cells

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiang-Jian [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Chen, Li-Na [Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100 (China); Zhang, Xuan [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Liu, Jin-Ting [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Chen, Ming-Yu [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Wu, Qiu-Rong [Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Miao, Jun-Ying, E-mail: miaojy@sdu.edu.cn [Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100 (China); Zhao, Bao-Xiang, E-mail: bxzhao@sdu.edu.cn [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2016-05-12

    NBDlyso with lysosome-locating morpholine moiety has been developed as a high selective and sensitive fluorescent pH probe. This probe can respond to acidic pH (2.0–7.0) in a short time (less than 1 min) and not almost change after continuously illuminated for an extended period by ultraviolet light. The fluorescence intensity of NBDlyso enhanced 100-fold in acidic solution, with very good linear relationship (R{sup 2} = 0.996). The pK{sub a} of probe NBDlyso is 4.10. Therefore, NBDlyso was used to detect lysosomal pH changes successfully. Besides, X-ray crystallography was used to verify the structure of NBDlyso, and the recognition mechanism involving photo-induced electron transfer was interpreted theoretically by means of DFT and TDDFT calculations skillfully when NBDlyso comes into play under the acidic condition. This probe showed good ability to sense pH change in living cell image. - Highlights: • An effective NBD-based fluorescent pH probe was developed. • The sensing mechanism was interpreted by theoretical calculation. • This probe was successfully used to monitor lysosoml pH changes in Hela cells.

  10. A NBD-based simple but effective fluorescent pH probe for imaging of lysosomes in living cells

    International Nuclear Information System (INIS)

    Cao, Xiang-Jian; Chen, Li-Na; Zhang, Xuan; Liu, Jin-Ting; Chen, Ming-Yu; Wu, Qiu-Rong; Miao, Jun-Ying; Zhao, Bao-Xiang

    2016-01-01

    NBDlyso with lysosome-locating morpholine moiety has been developed as a high selective and sensitive fluorescent pH probe. This probe can respond to acidic pH (2.0–7.0) in a short time (less than 1 min) and not almost change after continuously illuminated for an extended period by ultraviolet light. The fluorescence intensity of NBDlyso enhanced 100-fold in acidic solution, with very good linear relationship (R 2  = 0.996). The pK a of probe NBDlyso is 4.10. Therefore, NBDlyso was used to detect lysosomal pH changes successfully. Besides, X-ray crystallography was used to verify the structure of NBDlyso, and the recognition mechanism involving photo-induced electron transfer was interpreted theoretically by means of DFT and TDDFT calculations skillfully when NBDlyso comes into play under the acidic condition. This probe showed good ability to sense pH change in living cell image. - Highlights: • An effective NBD-based fluorescent pH probe was developed. • The sensing mechanism was interpreted by theoretical calculation. • This probe was successfully used to monitor lysosoml pH changes in Hela cells.

  11. Potential applications of near infrared auto-fluorescence spectral polarized imaging for assessment of food quality

    Science.gov (United States)

    Zhou, Kenneth J.; Chen, Jun

    2016-03-01

    The current growing of food industry for low production costs and high efficiency needs for maintenance of high-quality standards and assurance of food safety while avoiding liability issues. Quality and safety of food depend on physical (texture, color, tenderness etc.), chemical (fat content, moisture, protein content, pH, etc.), and biological (total bacterial count etc.) features. There is a need for a rapid (less than a few minutes) and accurate detection system in order to optimize quality and assure safety of food. However, the fluorescence ranges for known fluorophores are limited to ultraviolet emission bands, which are not in the tissue near infrared (NIR) "optical window". Biological tissues excited by far-red or NIR light would exhibit strong emission in spectral range of 650-1,100 nm although no characteristic peaks show the emission from which known fluorophores. The characteristics of the auto-fluorescence emission of different types of tissues were found to be different between different tissue components such as fat, high quality muscle food. In this paper, NIR auto-fluorescence emission from different types of muscle food and fat was measured. The differences of fluorescence intensities of the different types of muscle food and fat emissions were observed. These can be explained by the change of the microscopic structure of physical, chemical, and biological features in meat. The difference of emission intensities of fat and lean meat tissues was applied to monitor food quality and safety using spectral polarized imaging, which can be detect deep depth fat under the muscle food up to several centimeter.

  12. Probing the photoluminescence properties of gold nanoclusters by fluorescence lifetime correlation spectroscopy

    International Nuclear Information System (INIS)

    Yuan, C. T.; Lin, T. N.; Shen, J. L.; Lin, C. A.; Chang, W. H.; Cheng, H. W.; Tang, J.

    2013-01-01

    Gold nanoclusters (Au NCs) have attracted much attention for promising applications in biological imaging owing to their tiny sizes and biocompatibility. So far, most efforts have been focused on the strategies for fabricating high-quality Au NCs and then characterized by conventional ensemble measurement. Here, a fusion single-molecule technique combining fluorescence correlation spectroscopy and time-correlated single-photon counting can be successfully applied to probe the photoluminescence (PL) properties for sparse Au NCs. In this case, the triplet-state dynamics and diffusion process can be observed simultaneously and the relevant time constants can be derived. This work provides a complementary insight into the PL mechanism at the molecular levels for Au NCs in solution

  13. A "distorted-BODIPY"-based fluorescent probe for imaging of cellular viscosity in live cells.

    Science.gov (United States)

    Zhu, Hao; Fan, Jiangli; Li, Miao; Cao, Jianfang; Wang, Jingyun; Peng, Xiaojun

    2014-04-14

    Cellular viscosity is a critical factor in governing diffusion-mediated cellular processes and is linked to a number of diseases and pathologies. Fluorescent molecular rotors (FMRs) have recently been developed to determine viscosity in solutions or biological fluid. Herein, we report a "distorted-BODIPY"-based probe BV-1 for cellular viscosity, which is different from the conventional "pure rotors". In BV-1, the internal steric hindrance between the meso-CHO group and the 1,7-dimethyl group forced the boron-dipyrrin framework to be distorted, which mainly caused nonradiative deactivation in low-viscosity environment. BV-1 gave high sensitivity (x=0.62) together with stringent selectivity to viscosity, thus enabling viscosity mapping in live cells. Significantly, the increase of cytoplasmic viscosity during apoptosis was observed by BV-1 in real time. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. OPTIMIZATION OF LAMBLIASIS MICROSCOPIC DIAGNOSTICS BY THE METHOD OF POLARIZED FLUORESCENCE FOR PATIENTS WITH ROSACEA AND URTICARIAL

    Directory of Open Access Journals (Sweden)

    Maryana Kovalchuk

    2013-07-01

    Full Text Available Introduction: There is little information about diagnosis of concurrent lambliasis in patients with rosacea and urticaria. We used method of polarized fluorescence to diagnose liambliasis, taking into account belonging of macromolecular structures of unicellular parasites Giardia lamblia to the optically active substances with the properties of liquid crystals. Material and Methods: Lambliasis was diagnosed on the basis of feces parasitological research and duodenal contents by methods of light and optic microscopy and polarized fluorescence in 105 patients with rosacea and urticaria. Research results were processed by the method of variation statistics in the Statgraf program by using Student’s criterion. Results: Search results of lamblia in patients with rosacea and urticaria depended on the conditions of its holding, patients’ preparation and from the previously received basic therapy if it consisted absorbents. Due to the fact that the fluorescence polarization as a physical method does not require the use of any generally toxic, dye- fluorochromes, qualitative cyto fluorescent analysis of lamblia in greeting microdrugs enables to distinguish vegetative forms of cysts. Conclussions: Polarized fluorescence method allows optimize the microscopic diagnosis of lambliasis, increasing its sensitivity. Previous preparation for the laboratory examination of Giardia lamblia is needed for the best exposure of vermin for patients with rosacea and urticaria.

  15. An ultrasensitive method for the determination of melamine using cadmium telluride quantum dots as fluorescence probes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiafei; Li, Jin; Kuang, Huiyan; Feng, Lei; Yi, Shoujun; Xia, Xiaodong; Huang, Haowen [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education of China, Hunan University of Science and Technology, Xiangtan 411201 (China); Chen, Yong; Tang, Chunran [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Zeng, Yunlong, E-mail: yunlongzeng1955@126.com [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education of China, Hunan University of Science and Technology, Xiangtan 411201 (China); State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2013-11-13

    Graphical abstract: Melamine takes place of the TGA on the surface of TGA-CdTe QDs with negative charge to form melamine coated QDs changing the surface charge of the QDs, resulting the fluorescence quenched as the QDs aggregation occurred by electrostatic attraction of the two opposite charged nanocrystals. -- Highlights: •An ultrasensitive and selective method for the determination of melamine was developed at pH 11.0. •The selectivity of the method was improved. •The sensitivity of the method enhanced obviously as the CdTe QDs have higher QYs at pH 11. •The sensitivity and linear range for the analysis are size dependent using QDs PL probes. •Melamine takes the place of TGA resulting fluorescence quenched of QDs. -- Abstract: An ultrasensitive and simple method for the determination of melamine was developed based on the fluorescence quenching of thioglycolic acid (TGA) capped CdTe quantum dots (QDs) at pH 11.0. In strong alkaline aqueous solution, the selectivity of the method has been greatly improved due to most heavy metal ions show no interference as they are in the precipitation form or in their anion form. Furthermore, CdTe quantum dots have higher quantum yields at higher pH. The method has a wider concentration range and lower detection limit. The influence factors on the determination of melamine were investigated and the optimum conditions were determined. Under optimum conditions, the fluorescence intensity change of TGA coated CdTe quantum dots was linearly proportional to melamine over a concentration range from 1.0 × 10{sup −11} to 1.0 × 10{sup −5} mol L{sup −1} with a correlation coefficient of 0.9943 and a detection limit of 5 × 10{sup −12} mol L{sup −1}. The mechanism of fluorescence quenching of the QDs has been proposed based on the infrared spectroscopy information and electrophoresis experiments in presence of melamine under alkaline condition. The proposed method was employed to detect trace melamine in milk powder

  16. A Molecular Probe for the Detection of Polar Lipids in Live Cells.

    Directory of Open Access Journals (Sweden)

    Christie A Bader

    Full Text Available Lipids have an important role in many aspects of cell biology, including membrane architecture/compartment formation, intracellular traffic, signalling, hormone regulation, inflammation, energy storage and metabolism. Lipid biology is therefore integrally involved in major human diseases, including metabolic disorders, neurodegenerative diseases, obesity, heart disease, immune disorders and cancers, which commonly display altered lipid transport and metabolism. However, the investigation of these important cellular processes has been limited by the availability of specific tools to visualise lipids in live cells. Here we describe the potential for ReZolve-L1™ to localise to intracellular compartments containing polar lipids, such as for example sphingomyelin and phosphatidylethanolamine. In live Drosophila fat body tissue from third instar larvae, ReZolve-L1™ interacted mainly with lipid droplets, including the core region of these organelles. The presence of polar lipids in the core of these lipid droplets was confirmed by Raman mapping and while this was consistent with the distribution of ReZolve-L1™ it did not exclude that the molecular probe might be detecting other lipid species. In response to complete starvation conditions, ReZolve-L1™ was detected mainly in Atg8-GFP autophagic compartments, and showed reduced staining in the lipid droplets of fat body cells. The induction of autophagy by Tor inhibition also increased ReZolve-L1™ detection in autophagic compartments, whereas Atg9 knock down impaired autophagosome formation and altered the distribution of ReZolve-L1™. Finally, during Drosophila metamorphosis fat body tissues showed increased ReZolve-L1™ staining in autophagic compartments at two hours post puparium formation, when compared to earlier developmental time points. We concluded that ReZolve-L1™ is a new live cell imaging tool, which can be used as an imaging reagent for the detection of polar lipids in

  17. A Molecular Probe for the Detection of Polar Lipids in Live Cells.

    Science.gov (United States)

    Bader, Christie A; Shandala, Tetyana; Carter, Elizabeth A; Ivask, Angela; Guinan, Taryn; Hickey, Shane M; Werrett, Melissa V; Wright, Phillip J; Simpson, Peter V; Stagni, Stefano; Voelcker, Nicolas H; Lay, Peter A; Massi, Massimiliano; Plush, Sally E; Brooks, Douglas A

    2016-01-01

    Lipids have an important role in many aspects of cell biology, including membrane architecture/compartment formation, intracellular traffic, signalling, hormone regulation, inflammation, energy storage and metabolism. Lipid biology is therefore integrally involved in major human diseases, including metabolic disorders, neurodegenerative diseases, obesity, heart disease, immune disorders and cancers, which commonly display altered lipid transport and metabolism. However, the investigation of these important cellular processes has been limited by the availability of specific tools to visualise lipids in live cells. Here we describe the potential for ReZolve-L1™ to localise to intracellular compartments containing polar lipids, such as for example sphingomyelin and phosphatidylethanolamine. In live Drosophila fat body tissue from third instar larvae, ReZolve-L1™ interacted mainly with lipid droplets, including the core region of these organelles. The presence of polar lipids in the core of these lipid droplets was confirmed by Raman mapping and while this was consistent with the distribution of ReZolve-L1™ it did not exclude that the molecular probe might be detecting other lipid species. In response to complete starvation conditions, ReZolve-L1™ was detected mainly in Atg8-GFP autophagic compartments, and showed reduced staining in the lipid droplets of fat body cells. The induction of autophagy by Tor inhibition also increased ReZolve-L1™ detection in autophagic compartments, whereas Atg9 knock down impaired autophagosome formation and altered the distribution of ReZolve-L1™. Finally, during Drosophila metamorphosis fat body tissues showed increased ReZolve-L1™ staining in autophagic compartments at two hours post puparium formation, when compared to earlier developmental time points. We concluded that ReZolve-L1™ is a new live cell imaging tool, which can be used as an imaging reagent for the detection of polar lipids in different intracellular

  18. Cosmic microwave background polarization as a probe of the anomalous nature of the cold spot

    Science.gov (United States)

    Vielva, P.; Martínez-González, E.; Cruz, M.; Barreiro, R. B.; Tucci, M.

    2011-01-01

    One of the most interesting explanations for the non-Gaussian cold spot detected in the Wilkinson Microwave Anisotropy Probe (WMAP) data by Vielva et al. is that it arises from the interaction of the cosmic microwave background radiation with a cosmic texture. In this case, a lack of polarization is expected in the region of the spot, as compared to the typical values associated to large fluctuations of a Gaussian and isotropic random field. In addition, other physical processes related to a non-linear evolution of the gravitational field could lead to a similar scenario. However, some of these alternative scenarios (e.g. a large void in the large-scale structure) have been shown to be very unlikely. In this work we characterize the polarization properties of the cold spot under both hypotheses: a large Gaussian fluctuation and an anomalous feature generated, for instance, by a cosmic texture. We also propose a methodology to distinguish between them, and we discuss its discrimination power as a function of the instrumental noise level. In particular, we address the cases of current experiments, like WMAP and Planck, and others in development as the Q, U and I Joint Tenerife Experiment (QUIJOTE). We find that for an ideal experiment with a high-polarization sensitivity, the Gaussian hypothesis could be rejected at a significance level better than 0.8 per cent. While WMAP is far from providing useful information in this respect, we find that Planck will be able to reach a significance level of around 7 per cent; in addition, we show that the ground-based experiment QUIJOTE could provide a significance level of around 1 per cent, close to the ideal case. If these results are combined with the significance level found for the cold spot in temperature, the capability of QUIJOTE and Planck to reject the alternative hypothesis becomes 0.025 and 0.124 per cent, respectively.

  19. A Molecular Probe for the Detection of Polar Lipids in Live Cells

    Science.gov (United States)

    Bader, Christie A.; Shandala, Tetyana; Carter, Elizabeth A.; Ivask, Angela; Guinan, Taryn; Hickey, Shane M.; Werrett, Melissa V.; Wright, Phillip J.; Simpson, Peter V.; Stagni, Stefano; Voelcker, Nicolas H.; Lay, Peter A.; Massi, Massimiliano; Brooks, Douglas A.

    2016-01-01

    Lipids have an important role in many aspects of cell biology, including membrane architecture/compartment formation, intracellular traffic, signalling, hormone regulation, inflammation, energy storage and metabolism. Lipid biology is therefore integrally involved in major human diseases, including metabolic disorders, neurodegenerative diseases, obesity, heart disease, immune disorders and cancers, which commonly display altered lipid transport and metabolism. However, the investigation of these important cellular processes has been limited by the availability of specific tools to visualise lipids in live cells. Here we describe the potential for ReZolve-L1™ to localise to intracellular compartments containing polar lipids, such as for example sphingomyelin and phosphatidylethanolamine. In live Drosophila fat body tissue from third instar larvae, ReZolve-L1™ interacted mainly with lipid droplets, including the core region of these organelles. The presence of polar lipids in the core of these lipid droplets was confirmed by Raman mapping and while this was consistent with the distribution of ReZolve-L1™ it did not exclude that the molecular probe might be detecting other lipid species. In response to complete starvation conditions, ReZolve-L1™ was detected mainly in Atg8-GFP autophagic compartments, and showed reduced staining in the lipid droplets of fat body cells. The induction of autophagy by Tor inhibition also increased ReZolve-L1™ detection in autophagic compartments, whereas Atg9 knock down impaired autophagosome formation and altered the distribution of ReZolve-L1™. Finally, during Drosophila metamorphosis fat body tissues showed increased ReZolve-L1™ staining in autophagic compartments at two hours post puparium formation, when compared to earlier developmental time points. We concluded that ReZolve-L1™ is a new live cell imaging tool, which can be used as an imaging reagent for the detection of polar lipids in different intracellular

  20. Intravital imaging of fluorescent markers and FRET probes by DNA tattooing

    Directory of Open Access Journals (Sweden)

    Spencer David M

    2007-01-01

    Full Text Available Abstract Background Advances in fluorescence microscopy and mouse transgenesis have made it possible to image molecular events in living animals. However, the generation of transgenic mice is a lengthy process and intravital imaging requires specialized knowledge and equipment. Here, we report a rapid and undemanding intravital imaging method using generally available equipment. Results By DNA tattooing we transfect keratinocytes of living mice with DNA encoding fluorescent biosensors. Subsequently, the behavior of individual cells expressing these biosensors can be visualized within hours and using conventional microscopy equipment. Using this "instant transgenic" model in combination with a corrected coordinate system, we followed the in vivo behavior of individual cells expressing either FRET- or location-based biosensors for several days. The utility of this approach was demonstrated by assessment of in vivo caspase-3 activation upon induction of apoptosis. Conclusion This "instant skin transgenic" model can be used to follow the in vivo behavior of individual cells expressing either FRET- or location-based probes for several days after tattooing and provides a rapid and inexpensive method for intravital imaging in murine skin.

  1. Synthesis and spectral properties of novel chlorinated pH fluorescent probes

    Energy Technology Data Exchange (ETDEWEB)

    Wu Xianglong [Key Laboratory For Space Bioscience and Biotechnology, Faculty of Life Sciences, Northwestern Polytechnical University, Xi' an 710072 (China); Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), College of Chemistry and Materials Science, Northwest University, Tai Bai Bei Lu 229, Xi' an 710069, Shaanxi (China); Jin Xilang; Wang Yunxia [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), College of Chemistry and Materials Science, Northwest University, Tai Bai Bei Lu 229, Xi' an 710069, Shaanxi (China); Mei Qibing [Key Laboratory For Space Bioscience and Biotechnology, Faculty of Life Sciences, Northwestern Polytechnical University, Xi' an 710072 (China); Li Jianli, E-mail: lijianli@nwu.edu.c [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), College of Chemistry and Materials Science, Northwest University, Tai Bai Bei Lu 229, Xi' an 710069, Shaanxi (China); Shi Zhen, E-mail: gahpyudx@163.co [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), College of Chemistry and Materials Science, Northwest University, Tai Bai Bei Lu 229, Xi' an 710069, Shaanxi (China)

    2011-04-15

    Eight chlorinated fluoresceins have been synthesized by the reaction of chlorinated resorcinols with 4, 5, 6, 7-tetrachlorophthalic anhydride or 3, 6-dichloro-4-carboxyphthalic anhydride in the presence of methanesulfonic acid. The spectral properties of the chlorinated fluoresceins were studied. It was found that they have absorption and emission maxima at long wavelengths and high fluorescence quantum yields. Emission spectra of chlorinated fluoresceins shifted towards long wavelength with increase in chlorine. pH-dependent properties of chlorinated fluoresceins were studied in detail. These compounds showed a strongly pH-sensitive range of 3.0-7.0. These chlorinated fluoresceins will be used as pH probes for pH measurement of the cell because of the high quantum yield and strong pH-sensitivity. - Research highlights: Eight chlorinated fluoresceins have been synthesized in the presence of methanesulfonic acid. Emission spectra of these compounds shifted towards long wavelength with increase in chlorine. Eight chlorinated fluoresceins showed a strongly pH-sensitive range of 3.0-7.0. They have emission maxima at long wavelengths and high fluorescence quantum yields.

  2. Fluorescence study of protein-lipid complexes with a new symmetric squarylium probe.

    Science.gov (United States)

    Ioffe, Valeriya M; Gorbenko, Galyna P; Deligeorgiev, Todor; Gadjev, Nikolai; Vasilev, Aleksey

    2007-06-01

    The novel symmetric squarylium derivative SQ-1 has been synthesized and tested for its sensitivity to the formation of protein-lipid complexes. SQ-1 binding to the model membranes composed of zwitterionic lipid phosphatidylcholine (PC) and its mixtures with anionic lipid cardiolipin (CL) in different molar ratios was found to be controlled mainly by hydrophobic interactions. Lysozyme (Lz) and ribonuclease A (RNase) exerted an influence on the probe association with lipid vesicles resulting presumably from the competition between SQ-1 and the proteins for bilayer free volume and modification of its properties. The magnitude of this effect was much higher for lysozyme which may stem from the amphipathy of protein alpha-helix involved in the membrane binding. Varying membrane composition provides evidence for the dye sensitivity to both hydrophobic and electrostatic protein-lipid interactions. Fluorescence anisotropy studies uncovered the restriction of SQ-1 rotational mobility in lipid environment in the presence of Lz and RNase being indicative of the incorporation of the proteins into bilayer interior. The results of binding, fluorescence quenching and kinetic experiments suggested lysozyme-induced local lipid demixing upon protein association with negatively charged membranes with threshold concentration of CL for the lipid demixing being 10 mol%.

  3. Noninvasive imaging of multiple myeloma using near infrared fluorescent molecular probe

    Science.gov (United States)

    Hathi, Deep; Zhou, Haiying; Bollerman-Nowlis, Alex; Shokeen, Monica; Akers, Walter J.

    2016-03-01

    Multiple myeloma is a plasma cell malignancy characterized by monoclonal gammopathy and osteolytic bone lesions. Multiple myeloma is most commonly diagnosed in late disease stages, presenting with pathologic fracture. Early diagnosis and monitoring of disease status may improve quality of life and long-term survival for multiple myeloma patients from what is now a devastating and fatal disease. We have developed a near-infrared targeted fluorescent molecular probe with high affinity to the α4β1 integrin receptor (VLA-4)overexpressed by a majority of multiple myeloma cells as a non-radioactive analog to PET/CT tracer currently being developed for human diagnostics. A near-infrared dye that emits about 700 nm was conjugated to a high affinity peptidomimmetic. Binding affinity and specificity for multiple myeloma cells was investigated in vitro by tissue staining and flow cytometry. After demonstration of sensitivity and specificity, preclinical optical imaging studies were performed to evaluate tumor specificity in murine subcutaneous and metastatic multiple myeloma models. The VLA-4-targeted molecular probe showed high affinity for subcutaneous MM tumor xenografts. Importantly, tumor cells specific accumulation in the bone marrow of metastatic multiple myeloma correlated with GFP signal from transfected cells. Ex vivo flow cytometry of tumor tissue and bone marrow further corroborated in vivo imaging data, demonstrating the specificity of the novel agent and potential for quantitative imaging of multiple myeloma burden in these models.

  4. Synthesis of novel fluorescent probe Tb(III)-7-carboxymethoxy-4-methylcoumarin complex for sensing of DNA

    Energy Technology Data Exchange (ETDEWEB)

    Hussein, Belal H.M., E-mail: belalhussein102@yahoo.com [Department of Chemistry, Faculty of Science, Suez Canal University, Ismailia (Egypt); Azab, Hassan A. [Department of Chemistry, Faculty of Science, Suez Canal University, Ismailia (Egypt); Fathalla, Walid [Department of Mathematical and Physical Sciences, Faculty of Engineering, Port-Said University, Port-Said (Egypt); Ali, Sherin A.M. [Department of Mathematical and Physical Sciences, Faculty of Engineering, Suez Canal University, Ismailia (Egypt)

    2013-02-15

    New fluorescent probe Tb(III) (7-carboxymethoxy-4-methylcoumarin)2(SCN) (C2H5OH)(H2O) was synthesized and characterized by spectroscopy and thermal analysis. The absorption and fluorescence spectra of 7-carboxymethoxy-4-methylcoumarin (CMMC) and Tb(III)-CMMC complex have been measured in different solvents. The interactions of Tb(III)-CMMC complex with calf thymus nucleic acid (CT-DNA) have been investigated using steady state fluorescence measurements. The changes in the fluorescence intensity have been used for the quantitative determination of DNA with LOD of 3.45 ng in methanol-water (9:1, v/v). The association constants of DNA with Tb(III)-CMMC complex was found to be 2.62 Multiplication-Sign 1010 M{sup -1}. - Highlights: Black-Right-Pointing-Pointer New fluorescent probe Terbium (III)-7-carboxy methoxy-4-methylcoumarin complex has been synthesized and characterized. Black-Right-Pointing-Pointer FTIR spectrum of Tb(III)-complex shows a characteristic band for thiocyanate group. Black-Right-Pointing-Pointer DNA interaction with Terbium (III)-7-carboxy methoxy-4-methylcoumarin has been studied by fluorescence techniques. Black-Right-Pointing-Pointer The change in the fluorescence intensity has been used for the quantitative determination of DNA. Black-Right-Pointing-Pointer The result was better than most of the well-known methods including the ethidium bromide method.

  5. Two rhodamine lactam modulated lysosome-targetable fluorescence probes for sensitively and selectively monitoring subcellular organelle pH change

    International Nuclear Information System (INIS)

    Li, Hongmei; Wang, Cuiling; She, Mengyao; Zhu, Yuelu; Zhang, Jidong; Yang, Zheng; Liu, Ping; Wang, Yaoyu; Li, Jianli

    2015-01-01

    Be a powerful technique for convenient detection of pH change in living cells, especially at subcellular level, fluorescent probes has attracted more and more attention. In this work, we designed and synthesized three rhodamine lactam modulated fluorescent probes RS1, RS2 and RS3, which all respond sensitively toward weak acidity (pH range 4–6) via the photophysical property in buffer solution without interference from the other metal ions, and they also show ideal pKa values and excellent reversibility. Particularly, by changing the lone pair electrons distribution of lactam-N atom with different conjugations, RS2 and RS3 exhibit high quantum yield, negligible cytotoxicity and excellent permeability. They are suitable to stain selectively lysosomes of tumor cells and monitor its pH changes sensitively via optical molecular imaging. The above findings suggest that the probes we designed could act as ideal and easy method for investigating the pivotal role of H + in lysosomes and are potential pH detectors in disease diagnosis through direct intracellular imaging. - Highlights: • Two probes for sensitively and selectively monitoring weak acidic pH change. • The pKa of the probes was highly suitable for staining lysosomes in tumor cells. • The properties of those probes were changed by different conjugate system. • These probes have negligible cytotoxicity and good sensitivity in vivo.

  6. A single pH fluorescent probe for biosensing and imaging of extreme acidity and extreme alkalinity.

    Science.gov (United States)

    Chao, Jian-Bin; Wang, Hui-Juan; Zhang, Yong-Bin; Li, Zhi-Qing; Liu, Yu-Hong; Huo, Fang-Jun; Yin, Cai-Xia; Shi, Ya-Wei; Wang, Juan-Juan

    2017-07-04

    A simple tailor-made pH fluorescent probe 2-benzothiazole (N-ethylcarbazole-3-yl) hydrazone (Probe) is facilely synthesized by the condensation reaction of 2-hydrazinobenzothiazole with N-ethylcarbazole-3-formaldehyde, which is a useful fluorescent probe for monitoring extremely acidic and alkaline pH, quantitatively. The pH titrations indicate that Probe displays a remarkable emission enhancement with a pK a of 2.73 and responds linearly to minor pH fluctuations within the extremely acidic range of 2.21-3.30. Interestingly, Probe also exhibits strong pH-dependent characteristics with pK a 11.28 and linear response to extreme-alkalinity range of 10.41-12.43. In addition, Probe shows a large Stokes shift of 84 nm under extremely acidic and alkaline conditions, high selectivity, excellent sensitivity, good water-solubility and fine stability, all of which are favorable for intracellular pH imaging. The probe is further successfully applied to image extremely acidic and alkaline pH values fluctuations in E. coli cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. A ratiometric fluorescent probe based on boron dipyrromethene and rhodamine Förster resonance energy transfer platform for hypochlorous acid and its application in living cells

    International Nuclear Information System (INIS)

    Liu, Ying; Zhao, Zhi-Min; Miao, Jun-Ying; Zhao, Bao-Xiang

    2016-01-01

    We have developed a ratiometric fluorescent probe BRT based on boron dipyrromethene (BODIPY) and rhodamine-thiohydrazide Förster resonance energy transfer (FRET) platform for sensing hypochlorous acid (HOCl) with high selectivity and sensitivity. The probe can detect HOCl in 15 s with the detection limit of 38 nM. Upon mixing with HOCl the fluorescence colour of probe BRT changed from green to orange. Moreover, probe BRT was applied to successfully monitor HOCl in living RAW 264.7 cells. - Highlights: • A probe based on BODIPY and rhodamine was developed for sensing HOCl. • The probe could sense HOCl in a ratiometric manner based on the FRET platform in PBS buffer solution. • The probe can detect HOCl in 15 s accompanied with a fluorescence colour change. • This probe was successfully used to monitor HOCl in living RAW 264.7 cells.

  8. A rhodamine-labeled citalopram analogue as a high-affinity fluorescent probe for the serotonin transporter

    DEFF Research Database (Denmark)

    Zhang, Peng; Jørgensen, Trine Nygaard; Løland, Claus Juul

    2013-01-01

    A novel fluorescent ligand was synthesized as a high-affinity, high specificity probe for visualizing the serotonin transporter (SERT). The rhodamine fluorophore was extended from an aniline substitution on the 5-position of the dihydroisobenzofuran ring of citalopram (2, 1-(3-(dimethylamino)prop...

  9. Fluorescent water-Soluble Probes Based on Ammonium Cation Peg Substituted Perylenepisimides: Synthesis, Photophysical Properties, and Live Cell Images

    Science.gov (United States)

    Yang, Wei; Cai, Jiaxuan; Zhang, Shuchen; Yi, Xuegang; Gao, Baoxiang

    2018-01-01

    To synthesize perylenbisimides (PBI) fluorescent probes that will improve the water-soluble ability and the cytocompatibility, the synthesis and properties of fluorescent water-soluble probes based on dendritic ammonium cation polyethylene glycol (PEG) substituted perylenebisimides(GPDIs) are presented. As we expected, with increased ammonium cation PEG, the aggregation of the PBI in an aqueous solution is completely suppressed by the hydrophilic ammonium cation PEG groups. And the fluorescence quantum yield increases from 25% for GPDI-1 to 62% for GPDI-2. When incubated with Hela cells for 48 h, the viabilities are 71% (for GPDI-1) and 76% (for GPDI-2). Live cell imaging shows that these probes are efficiently internalized by HeLa cells. The study of the photophysical properties indicated increasing the ammonium cation PEG generation can increase the fluorescence quantum yield. Live cell imaging shows that with the ammonium cation PEG chains of perylenebisimides has high biocompatibility. The exceptionally low cytotoxicity is ascribed to the ammonium cation PEG chains, which protect the dyes from nonspecifically interacting with the extracellular proteins. Live cell imaging shows that ammonium cations PEG chains can promote the internalization of these probes.

  10. Single-molecule fluorescence polarization study of conformational change in archaeal group II chaperonin.

    Directory of Open Access Journals (Sweden)

    Ryo Iizuka

    Full Text Available Group II chaperonins found in archaea and in eukaryotic cytosol mediate protein folding without a GroES-like cofactor. The function of the cofactor is substituted by the helical protrusion at the tip of the apical domain, which forms a built-in lid on the central cavity. Although many studies on the change in lid conformation coupled to the binding and hydrolysis of nucleotides have been conducted, the molecular mechanism of lid closure remains poorly understood. Here, we performed a single-molecule polarization modulation to probe the rotation of the helical protrusion of a chaperonin from a hyperthermophilic archaeum, Thermococcus sp. strain KS-1. We detected approximately 35° rotation of the helical protrusion immediately after photorelease of ATP. The result suggests that the conformational change from the open lid to the closed lid state is responsible for the approximately 35° rotation of the helical protrusion.

  11. Utilization of physiological and taxonomic fluorescent probes to study Lactobacilli cells and response to pH challenge.

    Science.gov (United States)

    Olszewska, Magdalena A; Kocot, Aleksandra M; Nynca, Anna; Łaniewska-Trokenheim, Łucja

    2016-11-01

    pH stress is recognized as an important feature for Lactobacillus in relation to lifestyle and commercial utility. Hence, this study aims to investigate the cell function of Lactobacilli cells subjected to pHs between 7.0 and 2.0. For this purpose, the Lactobacilli isolates of vegetable origin were first hybridized with fluorescent oligonucleotide rRNA probes for detecting Lactobacillus species. Then, cells were exposed to pH stress and labelled with fluorescent probes, carboxyfluorescein diacetate (CFDA) and propidium iodine (PI), which provided the insight into esterase activity and membrane integrity of cells. Among isolates, fluorescence in situ hybridization (FISH) enabled us to specifically detect L. plantarum and L. brevis. Interestingly, FCM analysis revealed that at pHs between 7.0 and 4.0 the cell membrane was intact, while after the exposure at pH 3.0, and 2.0 became perturbed or impaired. Finally, L. brevis and L. plantarum differed from each other in fluorescence labeling behaviour and culturability. However, the results showed that the same standard protocol for labeling enables discrimination of subpopulations of tested species. Depending on the species, the substantial culturability loss was observed at pH 3.0 and 2.0. These results suggest that the taxonomic and physiological fluorescent probes could be suitable for in situ detection of specific bacteria and rapid assessment of the physiological status of cells. Copyright © 2016 Elsevier GmbH. All rights reserved.

  12. Label-free fluorescence strategy for sensitive detection of adenosine triphosphate using a loop DNA probe with low background noise.

    Science.gov (United States)

    Lin, Chunshui; Cai, Zhixiong; Wang, Yiru; Zhu, Zhi; Yang, Chaoyong James; Chen, Xi

    2014-07-15

    A simple, rapid, label-free, and ultrasensitive fluorescence strategy for adenosine triphosphate (ATP) detection was developed using a loop DNA probe with low background noise. In this strategy, a loop DNA probe, which is the substrate for both ligation and digestion enzyme reaction, was designed. SYBR green I (SG I), a double-stranded specific dye, was applied for the readout fluorescence signal. Exonuclease I (Exo I) and exonuclease III (Exo III), sequence-independent nucleases, were selected to digest the loop DNA probe in order to minimize the background fluorescence signal. As a result, in the absence of ATP, the loop DNA was completely digested by Exo I and Exo III, leading to low background fluorescence owing to the weak electrostatic interaction between SG I and mononucleotides. On the other hand, ATP induced the ligation of the nicking site, and the sealed loop DNA resisted the digestion of Exo I and ExoIII, resulting in a remarkable increase of fluorescence response. Upon background noise reduction, the sensitivity of the ATP determination was improved significantly, and the detection limitation was found to be 1.2 pM, which is much lower than that in almost all the previously reported methods. This strategy has promise for wide application in the determination of ATP.

  13. A two-photon fluorescent turn-on probe for imaging of SO2 derivatives in living cells and tissues

    International Nuclear Information System (INIS)

    Zhu, Xiaoyan; Zhu, Longming; Liu, Hong-wen; Hu, Xiaoxiao; Peng, Rui-zi; Zhang, Jing; Zhang, Xiao-Bing; Tan, Weihong

    2016-01-01

    SO 2 and its derivatives (bisulfite/sulfite) play crucial roles in several physiological processes. Therefore, development of reliable analytical methods for monitoring SO 2 and its derivatives in biological systems is very significant. In this paper, a FRET-based two-photon fluorescent turn-on probe, A-HCy, was proposed for specific detection of SO 2 derivatives through the bisulfite/sulfite-promoted Michael addition reaction. In this FRET system, an acedan (2-acetyl-6-dialkylaminonaphthalene) moiety was selected as a two-photon donor and a hemicyanine derivative served as both the quencher and the recognition unit for bisulfite/sulfite. A-HCy exhibited excellent selectivity and rapid response to HSO 3 − with a detection limit of 0.24 μM. More importantly, probe A-HCy was first successfully applied in two-photon fluorescence imaging of biological SO 2 derivatives in living cells and tissues, suggesting its great potential for practical application in biological systems. - Highlights: • A FRET-based two-photon fluorescent probe for detecting SO 2 derivatives was proposed. • The probe shows high sensitivity, excellent selectivity, rapid response as well as low cytotoxicity. • The probe was capable of detecting SO 2 derivatives up to 170 μm depth in tissues.

  14. CO as a marker and probe of polar vortex structure in the upper stratosphere and mesosphere

    Science.gov (United States)

    de Zafra, R. L.; Muscari, G.

    2003-04-01

    We present new ground-based measurements of polar stratospheric and mesospheric CO showing that it serves as an excellent tracer of vortex position, size, and descent at an altitude range where other information may be sparse or unreliable. Observations were made with a mm-wave spectrometer at Thule, Greenland (76.5o N, 68.7o W), and involved almost-daily measurements between January 17 and March 4, 2002. Our analysis is supplemented with occasional observations made at the geographic South Pole during both summer and winter periods of 1999. Mixing ratio profiles are retrieved from pressure-broadened line shape measurements of the 230 GHz rotational emission line, using a spectrometer with a bandwidth of 50 MHz and a resolution of about 65 kHz. Although Doppler broadening increasingly dominates over pressure broadening in the mesosphere, eventually frustrating profile retrieval, extensive testing shows that rather accurate retrievals (Lidar probe for temperature retrievals in 2003. We find CO to be a very good marker for the upper vortex (e.g. 50-70 km), in agreement with recent analysis of 1991-92 ISAMS data by Allen et al. [J. Atmos. Sci. 56, 563-583, 1999]. Large changes in the vertical profile are evident from outside to inside the polar vortex in this altitude range. Observed short-term changes at 50-70 km are consistent with vortex position below 50 km. Relative to its January height just outside the vortex, we find that the CO mixing ratio peak had descended by ˜10 km (to ˜55 km altitude) within the vortex by late January of 2002, while the external peak altitude is already much lower (˜65 km) than the CO peak at low latitudes or in polar summer. From earlier South Pole trial observations (with poorer signal/noise ratio) we find the total column density above 40 km in polar summer to be only 6-7% of its winter value. We have also compared our total column density values above 64 km to the same computations by Solomon et al. [J. Atmos. Sci., 42, 1072

  15. Fluorescence polarization assays to measure interactions between Gα subunits of heterotrimeric G proteins and regulatory motifs.

    Science.gov (United States)

    Maziarz, Marcin; Garcia-Marcos, Mikel

    2017-01-01

    Fluorescence polarization (FP) is a simple and sensitive method allowing for the quantification of interactions between proteins and fluorescently tagged small molecules like peptides. Heterotrimeric G proteins are critical signal transducing molecules and their activity is controlled by a complex network of regulatory proteins. Some of these regulators have defined short motifs (G proteins and subsequently modulate their activity. For these cases, FP represents a robust and quantitative method to characterize the G protein regulator interaction. Here we describe FP assays in a 384-well plate format to quantify interactions between Gα subunits of heterotrimeric G proteins and peptides corresponding to the Gα binding and activating (GBA) or GoLoco motifs, which are present in some proteins with guanine nucleotide exchange factor (GEF) (e.g., GIV/Girdin) or guanine nucleotide dissociation inhibitor (GDI) (e.g., RGS12) activity, respectively. This assay can be used to determine equilibrium dissociation constants, characterize the impact of single amino acid point mutations on the Gα-peptide interaction, and is suitable for high-throughput screening. © 2017 Elsevier Inc. All rights reserved.

  16. New method for preparing a liquid crystal polymer that exhibits linearly polarized white fluorescence

    International Nuclear Information System (INIS)

    Zheng Shijun; Kun, Wang; Kobayashi, Takaomi

    2011-01-01

    With the aim of developing a single-chain white-light-emitting polymer, liquid crystal (LC) polymers with a shish-kebab-type moiety on their cross-conjugated (p-phenylene)s-poly(p-phenylenevinylene)s main chain were synthesized by Gilch polymerization. They were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarizing optical microscopy (POM). 1 H-NMR indicated that the polymers had a shish-kebab structure, which strongly suppressed the formation of structural defects in the polymers. DSC revealed that the polymers had thermotropic LC properties, indicating that the LC polymers were enantiotropic. XRD showed that the polymers had a mesophase, which implies that they were in a smectic LC phase. A polymer with 'kebabs' of 2,5-bis(4'-alkoxyphenyl)benzene was combined with an aligned polyimide film with orientated microgrooves. The polymer main chain was aligned due to the orientation of the 'kebabs' of the uniform cross-conjugated structure. It lay between the kebabs and the 'shish' of the polymer main chains. The aligned polymer main chain emitted yellow light while and the oriented LC side chains emitted blue light emission. These two emissions resulted in linearly polarized white fluorescence.

  17. Imaging of Fluoride Ion in Living Cells and Tissues with a Two-Photon Ratiometric Fluorescence Probe

    Directory of Open Access Journals (Sweden)

    Xinyue Zhu

    2015-01-01

    Full Text Available A reaction-based two-photon (TP ratiometric fluorescence probe Z2 has been developed and successfully applied to detect and image fluoride ion in living cells and tissues. The Z2 probe was designed designed to utilize an ICT mechanism between n-butylnaphthalimide as a fluorophore and tert-butyldiphenylsilane (TBDPS as a response group. Upon addition of fluoride ion, the Si-O bond in the Z2 would be cleaved, and then a stronger electron-donating group was released. The fluorescent changes at 450 and 540 nm, respectively, made it possible to achieve ratiometric fluorescence detection. The results indicated that the Z2 could ratiometrically detect and image fluoride ion in living cells and tissues in a depth of 250 μm by two-photon microscopy (TPM.

  18. A fluorescence polarization based screening assay for identification of small molecule inhibitors of the PICK1 PDZ domain

    DEFF Research Database (Denmark)

    Thorsen, Thor S; Madsen, Kenneth L; Dyhring, Tino

    2011-01-01

    PDZ (PSD-95/Discs-large/ZO-1 homology) domains represent putative targets in several diseases including cancer, stroke, addiction and neuropathic pain. Here we describe the application of a simple and fast screening assay based on fluorescence polarization (FP) to identify inhibitors of the PDZ...

  19. A curcumin-based molecular probe for near-infrared fluorescence imaging of tau fibrils in Alzheimer's disease.

    Science.gov (United States)

    Park, Kwang-Su; Seo, Yujin; Kim, Mi Kyoung; Kim, Kyungdo; Kim, Yun Kyung; Choo, Hyunah; Chong, Youhoon

    2015-12-14

    In recent years, there has been growing interest in the near-infrared (NIR) fluorescence imaging of tau fibrils for the early diagnosis of Alzheimer's disease (AD). In order to develop a curcumin-based NIR fluorescent probe for tau fibrils, structural modification of the curcumin scaffold was attempted by combining the following rationales: the curcumin derivative should preserve its binding affinity to tau fibrils, and, upon binding to tau fibrils, the probe should show favorable fluorescence properties. To meet these requirements, we designed a novel curcumin scaffold with various aromatic substituents. Among the series, the curcumin derivative with a (4-dimethylamino-2,6-dimethoxy)phenyl moiety showed a significant change in its fluorescence properties (22.9-fold increase in quantum yield; Kd, 0.77 μM; λem, 620 nm; Φ, 0.32) after binding to tau fibrils. In addition, fluorescence imaging of tau-green fluorescent protein-transfected SHSY-5Y cells with confirmed that detected tau fibrils in live cells.

  20. A novel fluorescent probe (dtpa-bis(cytosine)) for detection of Eu(III) in rare earth metal ions

    Science.gov (United States)

    Yang, Fan; Ren, Peipei; Liu, Guanhong; Song, Youtao; Bu, Naishun; Wang, Jun

    2018-03-01

    In this paper, a novel fluorescent probe, dtpa-bis(cytosine), was designed and synthesized for detecting europium (Eu3 +) ion. Upon addition of Eu3 + ions into the dtpa-bis(cytosine) solution, the fluorescence intensity can strongly be enhanced. Conversely, adding other rare earth metal ions, such as Y3 +, Ce3 +, Pr3 +, Nd3 +, Sm3 +, Gd3 +, Tb3 +, Dy3 +, Ho3 +, Er3 +, Yb3 + and Lu3 +, into dtpa-bis(cytosine) solution, the fluorescence intensity is decreased slightly. Some parameters affecting the fluorescence intensity of dtpa-bis(cytosine) solution in the presence of Eu3 + ions were investigated, including solution pH value, Eu3 + ion concentration and interfering substances. The detection mechanism of Eu3 + ion using dtpa-bis(cytosine) as fluorescent probe was proposed. Under optimum conditions, the fluorescence emission intensities of EuIII-dtpa-bis(cytosine) at 375 nm in the concentration range of 0.50 × 10- 5 mol • L- 1-5.00 × 10- 5 mol • L- 1 of Eu3 + ion display a better linear relationship. The limit of detection (LOD) was determined as 8.65 × 10- 7 mol • L- 1 and the corresponding correlation coefficient (R2) of the linear equation is 0.9807. It is wished that the proposed method could be applied for sensitively and selectively detecting Eu3 + ion.

  1. Whole-slide imaging is a robust alternative to traditional fluorescent microscopy for fluorescence in situ hybridization imaging using break-apart DNA probes.

    Science.gov (United States)

    Laurent, Camille; Guérin, Maxime; Frenois, François-Xavier; Thuries, Valérie; Jalabert, Laurence; Brousset, Pierre; Valmary-Degano, Séverine

    2013-08-01

    Fluorescence in situ hybridization is an indispensable technique used in routine pathology and for theranostic purposes. Because fluorescence in situ hybridization techniques require sophisticated microscopic workstations and long procedures of image acquisition with sometimes subjective and poorly reproducible results, we decided to test a whole-slide imaging system as an alternative approach. In this study, we used the latest generation of Pannoramic 250 Flash digital microscopes (P250 Flash digital microscopes; 3DHISTECH, Budapest, Hungary) to digitize fluorescence in situ hybridization slides of diffuse large B cells lymphoma cases for detecting MYC rearrangement. The P250 Flash digital microscope was found to be precise with better definition of split signals in cells containing MYC rearrangement with fewer truncated signals as compared to traditional fluorescence microscopy. This digital technique is easier thanks to the preview function, which allows almost immediate identification of the tumor area, and the panning and zooming functionalities as well as a shorter acquisition time. Moreover, fluorescence in situ hybridization analyses using the digital technique appeared to be more reproducible between pathologists. Finally, the digital technique also allowed prolonged conservation of photos. In conclusion, whole-slide imaging technologies represent rapid, robust, and highly sensitive methods for interpreting fluorescence in situ hybridization slides with break-apart probes. In addition, these techniques offer an easier way to interpret the signals and allow definitive storage of the images for pathology expert networks or e-learning databases. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Microwave field distribution in a magic angle spinning dynamic nuclear polarization NMR probe.

    Science.gov (United States)

    Nanni, Emilio A; Barnes, Alexander B; Matsuki, Yoh; Woskov, Paul P; Corzilius, Björn; Griffin, Robert G; Temkin, Richard J

    2011-05-01

    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B(1S)) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4mm diameter sapphire rotor containing the sample. The predicted average B(1S) field is 13μT/W(1/2), where S denotes the electron spin. For a routinely achievable input power of 5W the corresponding value is γ(S)B(1S)=0.84MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (ϵ) vs. ω(1S)/(2π) for a sample of (13)C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. Single- and dual-fiber fluorescence probes: application to oil-film measurements in an internal combustion engine.

    Science.gov (United States)

    Ghandhi, J B

    2000-10-20

    Single- and dual-fiber fluorescence probes have been utilized to study oil-film behavior in a firing Diesel engine. A detailed analysis of the response characteristics of these probes was performed, and universal response curves have been generated through identification of the appropriate nondimensional parameters. For single-fiber probes a single curve was obtained, and for dual-fiber probes families of curves were identified based on three geometric dimensionless parameters. The complementary response characteristics of the single- and dual-fiber probes allows determination of the oil distribution within the piston-liner gap. The dual-fiber probe is not sensitive at small distances. Thus its signal originates solely from the piston surface, whereas the single-fiber probe is most sensitive at small distances and hence to the wall oil film. The engine data from the dual-fiber probe confirmed the presence of an oil film on the piston and provided a means of quantifying the transport of this oil within the engine.

  4. [Fluorescence polarization used to investigate the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field].

    Science.gov (United States)

    Zhang, Ying; Zeng, Xin-An; Wen, Qi-Biao; Li, Lin

    2008-01-01

    To know the lethal mechanism of microorganisms under pulsed electric field treatment, the relationship between the inactivation of Saccharomyces cerevisiae (CICC1308) cell and the permeability and fluidity changes of its cell membrane treated by pulsed electric field (0-25 kV x cm(-1), 0-266 ms) was investigated. With 1,6-diphenyl-1,3,5-hexatriene (DPH) used as a probe, the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field was expressed by fluorescence polarization. Results showed that the cell membrane fluidity decreases when the electric flied strength is up to 5 kV x cm(-1), and decreases with the increase in electric field strength and treatment time. The plate counting method and ultraviolet spectrophotometer were used to determine the cell viability and to investigate the cell membrane permeability, respectively, treated by pulsed electric field. Results showed that the lethal ratio and the content of protein and nucleic acid leaked from intracellular plasma increased with the increase in the electric field strength and the extension of treatment time. Even in a quite lower electric field of 5 kV x cm(-1) with a tiny microorganism lethal level, the increase in UV absorption value and the decrease in fluidity were significant. It was demonstrated that the cell membrane fluidity decreases with the increase in lethal ratio and cell membrane permeability. The viscosity of cell membrane increases with the decrease in fluidity. These phenomena indicated that cell membrane is one of the most key sites during the pulsed electric field treatment, and the increased membrane permeability and the decreased cell membrane fluidity contribute to the cell death.

  5. Mechanism of Lipid Binding of Human Apolipoprotein E3 by Hydrogen/Deuterium Exchange/Mass Spectrometry and Fluorescence Polarization.

    Science.gov (United States)

    Fabilane, Charina S; Nguyen, Patricia N; Hernandez, Roy V; Nirudodhi, Sasidhar; Duong, Mai; Maier, Claudia S; Narayanaswami, Vasanthy

    2016-01-01

    Human apolipoprotein E3 (apoE3) is an exchangeable apolipoprotein that plays a critical role in maintaining plasma cholesterol/triglyceride homeostasis. The C-terminal (CT) domain of apoE3 (residues 201-299) is composed of amphipathic α-helices C1: W210-S223, C2: V236-E266, and C3: D271-W276, which play a dominant role in mediating high-affinity lipid binding. The objective is to understand the accessibility of the CT domain at the sub-domain level and the mechanistic details regarding lipid-binding interaction. Hydrogen-deuterium exchange coupled to mass spectrometry (HDX/MS) of recombinant wild type (WT) apoE(201-299), chemical-induced unfolding monitored as changes in fluorescence polarization (FP) of labeled apoE(201-299) bearing a probe at specified sites, and lipid binding studies were carried out. HDX/MS revealed that residues towards the C-terminal end of the domain display significantly lower %D uptake compared to those towards the center, suggesting extensive protein-protein interaction in this segment. Functional assays showed that locking apoE(201-299) in an inter-molecular disulfide-bonded state at position 209, 223, 255, or 277 significantly decreases its ability to interact with lipids, especially when tethered towards the ends; this could be restored by reduction. Unfolding studies indicate that the C-terminal end offers less resistance to unfolding compared to the central portion of the domain. Taken together, our data suggest that two dimers of CT domain are juxtaposed around helix C3 leading to apoE3 tetramerization, and that dissociation to monomeric units is a required step in lipid binding, with helix C3 likely seeking stability via lipid interaction prior to helices C1 or C2.

  6. Turn-on fluorescence probes based on pyranine/viologen charge-transfer complexes for the determination of nucleotides

    Energy Technology Data Exchange (ETDEWEB)

    Schäferling, Michael, E-mail: Michael.schaeferling@utu.fi; Lang, Thomas; Schnettelker, Annette

    2014-10-15

    The formation of ground state charge-transfer complexes between pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid) and viologen (paraquat) derivatives is utilized for the design of novel fluoroionophores for the determination of phosphate species, particularly of nucleotides. The strong quenching of the pyranine fluorescence by viologen-type charge transfer acceptors can be countermanded if these are functionalized with triethylammonium groups that serve as recognition elements for phosphate anions. We report on the fluorogenic responses of these water-soluble molecular probes in presence of different phosphates. Absorbance measurements give additional information on the charge transfer complex formation and the interaction with nucleotides. The experimental data show that these aggregates form attractive, simple and versatile fluorescence turn-on probes for nucleoside triphosphates. The reversibility of the fluorescence response is demonstrated by means of an enzymatic model assay using ATPase for the decomposition of adenosine triphosphate. - Highlights: • Pyranine/viologen charge-transfer complexes as molecular probe for ATP recognition. • Fluorescence turn on mechanism. • Selective compared to other nucleotides and phosphate anions. • Fast and reversible response applicable to monitor enzymatic reactions.

  7. A spirobifluorene-based two-photon fluorescence probe for mercury ions and its applications in living cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Haibo, E-mail: xiaohb@shnu.edu.cn; Zhang, Yanzhen; Zhang, Wu; Li, Shaozhi; Tan, Jingjing; Han, Zhongying

    2017-05-01

    A novel spirobifluorene derivative SPF-TMS, which containing dithioacetal groups and triphenylamine units, was synthesized. The probing behaviors toward various metal ions were investigated via UV/Vis absorption spectra as well as one-photon fluorescence changes. The results indicated that SPF-TMS exhibits high sensitivity and selectivity for mercury ions. The detection limit was at least 8.6 × 10{sup −8}M, which is excellent comparing with other optical sensors for Hg{sup 2+}. When measured by two-photon excited fluorescence technique in THF at 800 nm, the two-photon cross-section of SPF-TMS is 272 GM. Especially, upon reaction with mercury species, SPF-TMS yielded another two-photon dye SPF-DA. Both SPF-TMS and SPF-DA emit strong two-photon induced fluorescence and can be applied in cell imaging by two-photon microscopy. - Highlights: • We report a spirobifluorene-based molecule as two-photon fluorescent probe with large two-photon cross-section. • The molecule has exclusive selectivity and sensitivity for mercury species. • The molecule has large two-photon emission changes before and after addition of Hg{sup 2+}. • Both the probe and the mercury ion-promoted reaction product can be applied in cell imaging by two-photon microscopy.

  8. Ultrasensitive fluorescent ratio imaging probe for the detection of glutathione ultratrace change in mitochondria of cancer cells.

    Science.gov (United States)

    Zhang, Hua; Wang, Caixia; Wang, Kui; Xuan, Xiaopeng; Lv, Qingzhang; Jiang, Kai

    2016-11-15

    Glutathione (GSH) ultratrace change in mitochondria of cancer cells can mildly and effectively induce cancer cells apoptosis in early stage. Thus, if GSH ultratrace change in mitochondria of cancer cells could be recognized and imaged, it will be beneficial for fundamental research of cancer therapy. There have reported a lot of fluorescent probes for GSH, but the fluorescent probe with ultrasensitivity and high selectivity for the ratio imaging of GSH ultratrace changes in mitochondria of cancer cells is scarce. Herein, based on different reaction mechanism of sulfonamide under different pH, a sulfonamide-based reactive ratiometric fluorescent probe (IQDC-M) was reported for the recognizing and imaging of GSH ultratrace change in mitochondria of cancer cells. The detection limit of IQDC-M for GSH ultratrace change is low to 2.02nM, which is far less than 1.0‰ of endogenic GSH in living cells. And during the recognition process, IQDC-M can emit different fluorescent signals at 520nm and 592nm, which results in it recognizing GSH ultratrace change on ratio mode. More importantly, IQDC-M recognizing GSH ultratrace change specifically occurs in mitochondria of cancer cells because of appropriate water/oil amphipathy (log P) of IQDC-M. So, these make IQDC-M possible to image and monitor GSH ultratrace change in mitochondria during cancer cells apoptosis for the first time. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Novel rhodamine Schiff base type naked-eye fluorescent probe for sensing Fe3 + and the application in cell

    Science.gov (United States)

    Chen, Xia; Sun, Wei; Bai, Yinjuan; Zhang, Feifei; Zhao, Junxia; Ding, Xiaohu

    2018-02-01

    Three rhodamine schiff-base type fluorescent sensors R1-R3 for detecting iron ion (Fe3 +), 2-furanacrolein rhodamine hydrazone (R1), furfural rhodamine hydrazone (R2) and 2-furanacrolein rhodamine ethylenediamine (R3) have been synthesized by using rhodamine B derivatives and furan derivatives as staring materials. And their recognition abilities for Fe3 + were studied by fluorescence spectroscopy. The result showed that R1 is a best selective probe for Fe3 + over other metal ions in EtOH/H2O (1:1, v/v) due to having 2-furanacrolein for unique space coordination structural. The recognition of Fe3 + and mechanism of the sensor were characterized and determined by fluorescence spectra and Fukui function. And the fluorescence intensity of the probe R1 for Fe3 + was proportional to its concentration with the linear correlation coefficient of 0.9965 and the binding constant of 7.66 × 104 M- 1. And the cell imaging experiment indicated a successful application of the probe R1 for Fe3 + in living cell.

  10. A fluorescent glycolipid-binding peptide probe traces cholesterol dependent microdomain-derived trafficking pathways.

    Directory of Open Access Journals (Sweden)

    Steffen Steinert

    . CONCLUSIONS/SIGNIFICANCE: The current work presents the characterization and trafficking behavior of a novel sphingolipid-binding fluorescent probe, the SBD peptide. We show that SBD binding to membranes is dependent on the presence of cholesterol, sphingomyelin, and complex glycolipids. In addition, SBD targeting through the endolysosomal pathway in neurons is highly sensitive to cholesterol perturbations, making it a potentially useful tool for the analysis of sphingolipid trafficking in disease models that involve changes in cholesterol metabolism and storage.

  11. Microwave assisted one-step green synthesis of fluorescent carbon nanoparticles from ionic liquids and their application as novel fluorescence probe for quercetin determination

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Deli; Yuan, Danhua [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); He, Hua, E-mail: dochehua@163.com [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, Nanjing 210009 (China); Gao, Mengmeng [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China)

    2013-08-15

    In this study, a new sensitive and convenient method for the determination of quercetin based on the fluorescence quenching of fluorescent carbon nanoparticles (CNPs) was developed. The CNPs derived from ionic liquids were prepared using a green and rapid microwave-assisted synthetic approach for the first time. The one-step green preparation process is simple and effective, neither a strong acid solvent nor surface modification reagent is needed, which makes this approach very suitable for large-scale production. The prepared CNPs were characterized by high-resolution transmission electron microscopy, Fourier transform infrared spectrometry, elemental analysis and spectrofluorometry. In NH{sub 3}–NH{sub 4}Cl buffer solution (pH 9.47), the fluorescence signals of CNPs decreased obviously with increase of the quercetin concentration. The effect of other coexisting foreign substances on the intensity of CNPs showed a low interference response. Under the optimum conditions, the fluorescence intensity presented a linear response versus quercetin concentration according to the Stern–Volmer equation with an excellent 0.9989 correlation coefficient. The linearity ranged from 2.87×10{sup −6} to 31.57×10{sup −6} mol L{sup −1} with the detection limit (3σ) of 9.88×10{sup −8} mol L{sup −1}. The recovery of this method was in the range of 93.3–105.1%. Therefore, the CNPs could to be a promising candidate as a fluorescence probe for the detection of trace levels of quercetin due to their advantages in low-cost production, low cytotoxicity, strong fluorescence and excellent biocompatibility. -- Highlights: ► Fluorescent CNPs were synthesized with microwave pyrolysis approach. ► Ionic liquids were used as sources of carbon and nitrogen for the first time. ► The formation and functionalization of CNPs were accomplished simultaneously. ► CNPs were used as fluorescent probes for the determination of quercetin. ► A sensitive and convenient method based

  12. The Synthesis of a Coumarin Carbohydrazide Dinuclear Copper Complex Based Fluorescence Probe and Its Detection of Thiols.

    Directory of Open Access Journals (Sweden)

    Guangjie He

    Full Text Available Small-molecule thiols, such as cysteine (CYS and glutathione (GSH, are essential for maintaining the cellular redox environment and play important roles in regulating various cellular physiological functions. A fluorescence probe (compound 1-Cu2+ for thiols based on coumarin carbohydrazide dinuclear copper complex was developed. Compound 1 was synthesized from the reaction of 7-(diethylamino-2-oxo-2H-chromene-3-carbohydrazide with 4-tert-butyl-2,6- diformylphenol. Accordingly, the copper complex (compound 1-Cu2+ was prepared by mixing compound 1 with 2 equivalents copper ions. Compound 1 had strong fluorescence while compound 1-Cu2+ hardly possessed fluorescence owing to the quenching nature of paramagnetism Cu2+ to the fluorescence molecule excited state. However, the fluorescence intensity of compound 1-Cu2+ was increased dramatically after the addition of thiol-containing amino acids, but not the other non-sulfhydryl amino acids. UV-vis absorption and fluorescence spectra indicated that compound 1-Cu2+ had good selectivity and sensitivity for thiols such as glutathione in CH3CN:H2O (3:2, v/v PBS solution. The fluorescence imaging experiments implied that compound 1-Cu2+ has potential application in thiol-containing amino acids detection in living cells.

  13. Glucagon-Secreting Alpha Cell Selective Two-Photon Fluorescent Probe TP-α: For Live Pancreatic Islet Imaging.

    Science.gov (United States)

    Agrawalla, Bikram Keshari; Chandran, Yogeswari; Phue, Wut-Hmone; Lee, Sung-Chan; Jeong, Yun-Mi; Wan, Si Yan Diana; Kang, Nam-Young; Chang, Young-Tae

    2015-04-29

    Two-photon (TP) microscopy has an advantage for live tissue imaging which allows a deeper tissue penetration up to 1 mm comparing to one-photon (OP) microscopy. While there are several OP fluorescence probes in use for pancreatic islet imaging, TP imaging of selective cells in live islet still remains a challenge. Herein, we report the discovery of first TP live pancreatic islet imaging probe; TP-α (Two Photon-alpha) which can selectively stain glucagon secreting alpha cells. Through fluorescent image based screening using three pancreatic cell lines, we discovered TP-α from a TP fluorescent dye library TPG (TP-Green). In vitro fluorescence test showed that TP-α have direct interaction and appear glucagon with a significant fluorescence increase, but not with insulin or other hormones/analytes. Finally, TP-α was successfully applied for 3D imaging of live islets by staining alpha cell directly. The newly developed TP-α can be a practical tool to evaluate and identify live alpha cells in terms of localization, distribution and availability in the intact islets.

  14. Circular polarization of gravitational waves from non-rotating supernova cores: a new probe into the pre-explosion hydrodynamics

    Science.gov (United States)

    Hayama, Kazuhiro; Kuroda, Takami; Kotake, Kei; Takiwaki, Tomoya

    2018-04-01

    We present an analysis of the circular polarization of gravitational-waves (GWs) using results from three-dimensional (3D), general relativistic (GR) core-collapse simulations of a non-rotating 15M⊙ star. For the signal detection, we perform a coherent network analysis taking into account the four interferometers of LIGO Hanford, LIGO Livingston, VIRGO, and KAGRA. We focus on the Stokes V parameter, which directly characterizes the asymmetry of the GW circular polarization. We find that the amplitude of the GW polarization becomes bigger for our 3D-GR model that exhibits strong activity of the standing accretion shock instability (SASI). Our results suggest that the SASI-induced accretion flows to the proto-neutron star (PNS) lead to a characteristic, low-frequency modulation (100 ˜ 200 Hz) in both the waveform and the GW circular polarization. By estimating the signal-to-noise ratio of the GW polarization, we demonstrate that the detection horizon of the circular polarization extends by more than a factor of several times farther comparing to that of the GW amplitude. Our results suggest that the GW circular polarization, if detected, could provide a new probe into the pre-explosion hydrodynamics such as the SASI activity and the g-mode oscillation of the PNS.

  15. Interfacing click chemistry with automated oligonucleotide synthesis for the preparation of fluorescent DNA probes containing internal xanthene and cyanine dyes

    DEFF Research Database (Denmark)

    Astakhova, I Kira; Wengel, Jesper

    2013-01-01

    for the first time performed solid-phase copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click labeling during the automated phosphoramidite oligonucleotide synthesis followed by postsynthetic click reactions in solution. We demonstrate that our novel strategy is rapid and efficient for the preparation...... Stokes shifts (40-110 nm), quenched fluorescence of single-stranded probes accompanied by up to 7.7-fold light-up effect of emission upon target DNA/RNA binding, remarkable sensitivity to single-nucleotide mismatches, generally high fluorescence brightness values (FB up to 26), and hence low limit...

  16. Probe development for detection of TERRA 1 intramolecular G-quadruplex formation using a fluorescent adenosine derivative.

    Science.gov (United States)

    Kim, In Sun; Seo, Young Jun

    2014-03-15

    We developed a probing system to detect the intramolecular G-quadruplex of telomeric repeat-containing RNA (TERRA 1). We used a fluorescent adenosine derivative rA(py) as a fluorophore and incorporated it into the dangling position of the parallel-type G-quadruplex sequence of TERRA 1. The rA(py)-modified G-quadruplex structure exhibited a strong fluorescence emission signal, while the emission signals of the single-strand and duplex structures were much lower. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Establishment of a novel immunoassay system for rapid detection of 2,4-dichlorophenoxyacetic acid residues based on magnetic-fluorescent probes

    Directory of Open Access Journals (Sweden)

    WANG Yuanfeng

    2014-12-01

    Full Text Available A novel immunoassay system based on magnetic-fluorescent probes was established to detect 2.4-dichlorophenoxyacetic acid (2,4-D residue in liquid system in food and agricultural products.The composites of anti-2,4-D antibody bound to Fe3O4@SiO2-NH2 was employed as the solid phase as well as magnetic probe.The composites composed of 2,4-D-OVA labeled with CdTe@SiO2-NH2 as the fluorescent probe was used to produce fluorescent signal.2,4-D and its fluorescent probe competed binding the antibody on the surface of the magnetic probe.The optimization of 2,4-D-OVA dosage,coupling PH and reaction time in preparing the fluorescent probe were investigated.It showed that in the synthesis of fluorescent probe 8.2 was the optimal pH,70 min was the optimal coupling time,500 μL amount of 2,4-D-OVA.The standard curve was obtained with the concentration of 2,4-D and the maximum fluorescence intensity.The detection limit of the assay was gotten and it was 3.55×10-8.One reaction step and one washing step were needed.The assay significantly shortened the testing time and amplified the detection signal compared with classic ELISA.

  18. A novel turn-on fluorescent probe for Al3 + and Fe3 + in aqueous solution and its imaging in living cells

    Science.gov (United States)

    Dai, Yanpeng; Fu, Jiaxin; Yao, Kun; Song, Qianqian; Xu, Kuoxi; Pang, Xiaobin

    2018-03-01

    A quinoline-based fluorescence probe has been prepared and characterized. Probe 1 showed a selective sensing ability for Al3 + and Fe3 + ions through fluorescence enhancement response at 515 nm when it was excited at 360 nm. In the presence of Fe3 + ion, probe 1 exhibited a detection limit of 2.10 × 10- 6 M. As for Al3 +, its detection limit of 3.58 × 10- 7 M was significantly lower than the highest limit of Al3 + in drinking water recommended by the WHO (7.41 μM), representing a rare example in reported fluorescent probe for Al3 + ion. The fluorescence microscopy experiments have demonstrated that probe 1 could be used in live cells for the detection of Al3 + and Fe3 + ions.

  19. A Fluorescence Light-Up Ag Nanocluster Probe that Discriminates Single-Nucleotide Variants by Emission Color

    OpenAIRE

    Yeh, Hsin-Chih; Sharma, Jaswinder; Shih, Ie-Ming; Vu, Dung M.; Martinez, Jennifer S.; Werner, James H.

    2012-01-01

    Rapid and precise screening of small genetic variations, such as single-nucleotide polymorphisms (SNPs), among an individual’s genome is still an unmet challenge at point-of-care settings. One crucial step towards this goal is the development of discrimination probes that require no enzymatic reaction and are easy to use. Here we report a new type of fluorescent molecular probe, termed a chameleon NanoCluster Beacon (cNCB), that lights up into different colors upon binding SNP targets. NanoCl...

  20. Development and cytotoxicity of Schiff base derivative as a fluorescence probe for the detection of L-Arginine

    Science.gov (United States)

    Shang, Xuefang; Li, Jie; Guo, Kerong; Ti, Tongyu; Wang, Tianyun; Zhang, Jinlian

    2017-04-01

    Inspired from biological counter parts, chemical modification of Schiff base derivatives with function groups may provide a highly efficient method to detect amino acids. Therefore, a fluorescent probe involving Schiff base and hydroxyl group has been designed and prepared, which showed high response and specificity for Arginine (Arg) among normal eighteen standard kinds of amino acids (Alanine, Valine, Leucine, Isoleucine, Methionine, Asparticacid, Glutamicacid, Arginine, Glycine, Serine, Threonine, Asparagine, Phenylalanine, Histidine, Tryptophan, Proline, Lysine, Glutamine, Tyrosine and Cysteine). Furthermore, theoretical investigation further illustrated the possible binding mode in the host-guest interaction and the roles of molecular frontier orbitals in molecular interplay. In addition, the synthesized fluorescent probe exhibited high binding ability for Arg and low cytotoxicity to MCF-7 cells over a concentration range of 0-200 μg mL-1 which can be also used as a biosensor for the Arg detection in vivo.

  1. Rapid screening of aflatoxin B1 in beer by fluorescence polarization immunoassay.

    Science.gov (United States)

    Beloglazova, N V; Eremin, S A

    2015-09-01

    This manuscript describes the development of a sensitive, fast and easily-performed fluorescence polarization immunoassay (FPIA) for the mycotoxin aflatoxin B1 (AFB1) in various beer samples, both lager and dark. The highest sensitivity was determined for six poly- and monoclonal antibodies selective towards aflatoxins. The sample pretreatment design was emphasized since beer samples are characterized by extremely diverse matrices. Herein, the choice of sorbent for effective removal of matrix interferences prior to analysis was crucial. The samples were diluted with a borate buffer solution containing 1% PEG 6000 and passed through the clean-up column packed with NH2-derivated silica. This sample pretreatment technique was perfectly suitable for the FPIA of lager beer samples, but for dark beer and ale it did not suffice. An artificial matrix was constructed to plot a calibration curve and quantify the results of the latter samples. The developed immunoassay was characterized by a limit of detection of 1 ng mL(-1). Apparent recovery values of 89-114% for lager and 80-125% for dark beer were established. The FPIA data for AFB1 was characterized by elevated linear regression coefficients, 0.9953 for spiked lager and 0.9895 for dark beer samples respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Tilting and Wobble of Myosin V by High-Speed Single-Molecule Polarized Fluorescence Microscopy

    Science.gov (United States)

    Beausang, John F.; Shroder, Deborah Y.; Nelson, Philip C.; Goldman, Yale E.

    2013-01-01

    Myosin V is biomolecular motor with two actin-binding domains (heads) that take multiple steps along actin by a hand-over-hand mechanism. We used high-speed polarized total internal reflection fluorescence (polTIRF) microscopy to study the structural dynamics of single myosin V molecules that had been labeled with bifunctional rhodamine linked to one of the calmodulins along the lever arm. With the use of time-correlated single-photon counting technology, the temporal resolution of the polTIRF microscope was improved ∼50-fold relative to earlier studies, and a maximum-likelihood, multitrace change-point algorithm was used to objectively determine the times when structural changes occurred. Short-lived substeps that displayed an abrupt increase in rotational mobility were detected during stepping, likely corresponding to random thermal fluctuations of the stepping head while it searched for its next actin-binding site. Thus, myosin V harnesses its fluctuating environment to extend its reach. Additional, less frequent angle changes, probably not directly associated with steps, were detected in both leading and trailing heads. The high-speed polTIRF method and change-point analysis may be applicable to single-molecule studies of other biological systems. PMID:23528086

  3. DART: Recent Advances in Remote Sensing Data Modeling With Atmosphere, Polarization, and Chlorophyll Fluorescence

    Science.gov (United States)

    Gastellu-Etchegorry, Jean-Phil; Lauret, Nicolas; Yin, Tiangang; Landier, Lucas; Kallel, Abdelaziz; Malenovsky, Zbynek; Bitar, Ahmad Al; Aval, Josselin; Benhmida, Sahar; Qi, Jianbo; hide

    2017-01-01

    To better understand the life-essential cycles and processes of our planet and to further develop remote sensing (RS) technology, there is an increasing need for models that simulate the radiative budget (RB) and RS acquisitions of urban and natural landscapes using physical approaches and considering the three-dimensional (3-D) architecture of Earth surfaces. Discrete anisotropic radiative transfer (DART) is one of the most comprehensive physically based 3-D models of Earth-atmosphere radiative transfer, covering the spectral domain from ultraviolet to thermal infrared wavelengths. It simulates the optical 3-DRB and optical signals of proximal, aerial, and satellite imaging spectrometers and laser scanners, for any urban and/or natural landscapes and for any experimental and instrumental configurations. It is freely available for research and teaching activities. In this paper, we briefly introduce DART theory and present recent advances in simulated sensors (LiDAR and cameras with finite field of view) and modeling mechanisms (atmosphere, specular reflectance with polarization and chlorophyll fluorescence). A case study demonstrating a novel application of DART to investigate urban landscapes is also presented.

  4. A compact fluorescence polarization analyzer with high-transmittance liquid crystal layer

    Science.gov (United States)

    Wakao, Osamu; Satou, Ken; Nakamura, Ayano; Sumiyoshi, Ken; Shirokawa, Masanori; Mizokuchi, Chikaaki; Shiota, Kunihiro; Maeki, Masatoshi; Ishida, Akihiko; Tani, Hirofumi; Shigemura, Koji; Hibara, Akihide; Tokeshi, Manabu

    2018-02-01

    Fluorescence polarization (FP) offers easy operation and rapid processing, making it implementable in molecular interaction analysis. Previously we have developed a unique FP measurement system using a liquid crystal (LC) layer and an image sensor. The system is based on a principle of synchronized detection between the switching rate of the LC layer and the sampling rate of the CCD. The FP system realized simultaneous multiple sample detection; however, the measurement precision was lower than that of the conventional FP apparatus. The main drawbacks were low light transmittance of the LC layer and insufficient synchronization between the LC layer and CCD. In this paper, we developed a new FP analyzer based on LC-CCD synchronization detection. By using a newly designed LC with high transmittance and improving synchronization, the performance of the system has been dramatically improved. Additionally, we reduced the cost by using an inexpensive CCD and an LED as the excitation source. Simultaneous FP immunoassay of multiple samples of prostaglandin E2 was performed. The error rate of the FP system is reduced from 16.9% to 3.9%, as comparable to the commercial conventional FP system.

  5. Simultaneous detection of four common oral Candida species from blood samples by the fluorescence polarization assay.

    Science.gov (United States)

    He, Yuhong; Geng, Wei; Wang, Peihuan; Xi, Lanlan; Wang, Zhaoling; Wu, Gaoyi; Wang, Chunling

    2015-03-01

    The genus Candida is both the commensal microbe and the opportunistic pathogen, containing approximately 200 species inhabiting in oral cavity of 53 % of the general population. Candida species can cause the diseases from local mucosal infections to systemic mycoses, even life-threatening infections in immunocompromised individuals. The timely differentiation of Candida species is important for the guidance of clinical medication. Four common Candida species in Chinese population (Candida albicans, Candida tropicalis, Candida glabrata, Candida krusei) were chosen as the targets to develop the rapid screening method in this work. Combined with amplification by asymmetric PCR, this parallel fluorescence polarization (FP) immunoassay is carried out in homogeneous solution phase. The limit of detection of the assay was shown to be 50 copies/mL in blood samples. The evaluation in multicenter manner showed excellent reproducibility and stability. The comparison between DNA sequencing and the FP immunoassay indicated that there was no significant difference between these methods. This molecular strategy-based method is simple, rapid, and feasible for identifying common Candida species and thereby holding great potential in the application of clinical laboratories.

  6. Heterologous strategy enhancing the sensitivity of the fluorescence polarization immunoassay of clinafloxacin in goat milk.

    Science.gov (United States)

    Chen, Jiahong; Shanin, Ilya A; Lv, Shuwei; Wang, Qiang; Mao, Chuanbin; Xu, Zhenlin; Sun, Yuanming; Wu, Qing; Eremin, Sergei A; Lei, Hongtao

    2016-03-15

    Clinafloxacin is used for the treatment of disease in food-producing animals, e.g. Brucella melitensis, which often occurs in goats; however, the clinafloxacin residue in goat milk may harm human health and result in the development of drug-resistant bacterial strains or allergies. Despite this, there is not a rapid, sensitive and accurate analytical method in goat milk for rapid screening or monitoring purposes. One homologous and five heterologous tracers were designed and compared for fluorescence polarization immunoassay (FPIA) optimization. Based on the combination of a heterologous tracer (PAZ-FITC, synthesized with pazufloxacin and FITC) and the antibody against clinafloxacin, a highly sensitive FPIA was established for the detection of clinafloxacin residue in goat milk for the first time. The IC50 value was 29.3 µg L(-1) for clinafloxacin in the heterologous format - six times lower than that of the combination of the homologous tracers and the antibody. The recoveries ranged from 86.8% to 104.5%, with the relative standard deviation ranging from 4.1% to 7.2%. Validation by high-performance liquid chromatography (HPLC) confirmed that the results obtained from the proposed FPIA were in agreement with those of HPLC. This proposed heterologous strategy for enhanced FPIA is sensitive and rapid enough for the high-throughput detection of clinafloxacin residue in goat milk. © 2015 Society of Chemical Industry.

  7. Screening for Antifibrotic Compounds Using High Throughput System Based on Fluorescence Polarization

    Directory of Open Access Journals (Sweden)

    Branko Stefanovic

    2014-04-01

    Full Text Available Fibroproliferative diseases are one of the leading causes of death worldwide. They are characterized by reactive fibrosis caused by uncontrolled synthesis of type I collagen. There is no cure for fibrosis and development of therapeutics that can inhibit collagen synthesis is urgently needed. Collagen α1(I mRNA and α2(I mRNA encode for type I collagen and they have a unique 5' stem-loop structure in their 5' untranslated regions (5'SL. Collagen 5'SL binds protein LARP6 with high affinity and specificity. The interaction between LARP6 and the 5'SL is critical for biosynthesis of type I collagen and development of fibrosis in vivo. Therefore, this interaction represents is an ideal target to develop antifibrotic drugs. A high throughput system to screen for chemical compounds that can dissociate LARP6 from 5'SL has been developed. It is based on fluorescence polarization and can be adapted to screen for inhibitors of other protein-RNA interactions. Screening of 50,000 chemical compounds yielded a lead compound that can inhibit type I collagen synthesis at nanomolar concentrations. The development, characteristics, and critical appraisal of this assay are presented.

  8. Characterization and optimization of a red-shifted fluorescence polarization ADP detection assay.

    Science.gov (United States)

    Kleman-Leyer, Karen M; Klink, Tony A; Kopp, Andrew L; Westermeyer, Thane A; Koeff, Mark D; Larson, Brad R; Worzella, Tracy J; Pinchard, Cori A; van de Kar, Sebastianus A T; Zaman, Guido J R; Hornberg, Jorrit J; Lowery, Robert G

    2009-02-01

    ATP depletion and ADP formation are generic detection methods used for the identification of kinase and other ATP-utilizing enzyme inhibitors in high-throughput screening campaigns. However, the most widely used nucleotide detection approaches require high ATP consumption rates or involve the use of coupling enzymes, which can complicate the selection of lead compounds. As an alternative, we have developed the Transcreener (BellBrook Labs, Madison, WI) platform, which relies on the direct immunodetection of nucleotides. Here we describe the development of antibodies with >100-fold selectivity for ADP versus ATP, which enable robust detection of initial velocity rates (Z' > 0.7 at 10% substrate consumption) at ATP concentrations ranging from 0.1 microM to 1,000 microM in a competitive fluorescence polarization (FP) immunoassay. Competitive binding experiments indicate similar affinities for other nucleotide diphosphates, including 2' -deoxy ADP, GDP, and UDP. The antibody-tracer complex and the red-shifted, ratiometric FP signal are stable for at least 24 h at room temperature, providing suitable conditions for high-throughput screening. A method for calculating a kinase ATP Km with this FP immunoassay is also presented. The Transcreener ADP assay provides a simple, generic assay platform for inhibitor screening and selectivity profiling that can be used for any ADP-generating enzyme.

  9. Development of an in situ polarization-dependent total-reflection fluorescence XAFS measurement system.

    Science.gov (United States)

    Chun, W J; Tanizawa, Y; Shido, T; Iwasawa, Y; Nomura, M; Asakura, K

    2001-03-01

    An in situ polarization-dependent total-reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) spectroscopy system has been developed, which enables PTRF-XAFS experiments to be performed in three different orientations at various temperatures (273-600 K) and pressures (10(-10) approximately 760 torr). The system consists of a measurement chamber and a preparation chamber. The measurement chamber has a high-precision six-axis goniometer and a multielement solid-state detector. Using a transfer chamber, also operated under ultra-high-vacuum conditions, the sample can be transferred to the measurement chamber from the preparation chamber, which possesses low-energy electron diffraction, Auger electron spectroscopy and X-ray photoelectron spectroscopy facilities, as well as a sputtering gun and an annealing system. The in situ PTRF-EXAFS for Cu species on TiO2 (110) has been measured in three different orientations, revealing anisotropic growth of Cu under the influence of the TiO2 (110) surface.

  10. Multi-element analysis of pyrite ores using polarized energy-dispersive X-ray fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ustuendag, Zafer [Department of Chemistry, Faculty of Science, Ankara University, Ankara (Turkey)]. E-mail: zustun@science.ankara.edu.tr; Ustuendag, Ilknur [Department of Physics Engineering, Faculty of Engineering, Hacettepe University, Ankara (Turkey); Kagan Kadioglu, Yusuf [Department of Geological Engineering, Faculty of Engineering, Ankara University, Ankara (Turkey)

    2007-07-15

    X-ray fluorescence (XRF) spectrometry is used worldwide in geological material analysis. This study, applies polarized energy-dispersive X-ray fluorescence (PEDXRF) Spectrometer and compares in the samples of Rize-Cayeli and Mardin pyrite ores. The samples of pyrite ore were collected from the Rize and Mardin in Turkey. The prepared samples were analyzed using a PEDXRF spectrometer. The result of the analysis shows the presence of many elements including rare-earth elements (from Na to Th). The accuracy and precision of the technique for chemical analysis is demonstrated by analyzing USGS standards, GEOL, GBW 7109 and GBW-7309 sediment.

  11. Polarity-Tunable Host Materials and Their Applications in Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes.

    Science.gov (United States)

    Xie, Gaozhan; Chen, Dongjun; Li, Xianglong; Cai, Xinyi; Li, Yunchuan; Chen, Dongcheng; Liu, Kunkun; Zhang, Qian; Cao, Yong; Su, Shi-Jian

    2016-10-04

    A series of polarity-tunable host materials were developed based on oligocarbazoles and diphenylphosphine oxide, and their polarities can be tuned through increasing distance of acceptor and donor units. Density functional theory calculations were employed, and photoluminescence spectra in different polar solvents were measured to illustrate different polarities of these host materials. As CZPO has relatively stronger polarity, electroluminescence (EL) spectrum of solution-processed device based on 6 wt % PXZDSO2:CZPO is 7 nm red-shifted relative to that of other host materials based devices. Besides, a comparable impressive external quantum efficiency (EQE) value of 18.7% is achieved for an evaporation-processed yellow device consisting of FCZBn, which is superior to that of the device based on CBP (4,4'-dicarbazolyl-1,1'-biphenyl) (17.0%), and its efficiency roll-off is also obviously reduced, giving an EQE value as high as 16.3% at the luminance of 1000 cd/m 2 . In addition, from CZPO to FCZBn as the polarities of host materials decrease, EL spectra of solution-processed devices based on DMAC-DPS emitter blue-shift constantly from 496 to 470 nm. The current work gives a constructive approach to control EL spectra of organic light-emitting diodes with a fixed thermally activated delayed fluorescence emitter by tuning the polarities of host materials.

  12. Analysis of chemical equilibrium of silicon-substituted fluorescein and its application to develop a scaffold for red fluorescent probes.

    Science.gov (United States)

    Hirabayashi, Kazuhisa; Hanaoka, Kenjiro; Takayanagi, Toshio; Toki, Yuko; Egawa, Takahiro; Kamiya, Mako; Komatsu, Toru; Ueno, Tasuku; Terai, Takuya; Yoshida, Kengo; Uchiyama, Masanobu; Nagano, Tetsuo; Urano, Yasuteru

    2015-09-01

    Fluorescein is a representative green fluorophore that has been widely used as a scaffold of practically useful green fluorescent probes. Here, we report synthesis and characterization of a silicon-substituted fluorescein, i.e., 2-COOH TokyoMagenta (2-COOH TM), which is a fluorescein analogue in which the O atom at the 10' position of the xanthene moiety of fluorescein is replaced with a Si atom. This fluorescein analogue forms a spirolactone ring via intramolecular nucleophilic attack of the carboxylic group in a pH-dependent manner. Consequently, 2-COOH TM exhibits characteristic large pH-dependent absorption and fluorescence spectral changes: (1) 2-COOH TM is colorless at acidic pH, whereas fluorescein retains observable absorption and fluorescence even at acidic pH, and the absorption maximum is also shifted; (2) the absorption spectral change occurs above pH 7.0 for 2-COOH TM and below pH 7.0 for fluorescein; (3) 2-COOH TM shows a much sharper pH response than fluorescein because of its pKa inversion, i.e., pKa1 > pKa2. These features are also different from those of a compound without the carboxylic group, 2-Me TokyoMagenta (2-Me TM). Analysis of the chemical equilibrium between pH 3.0 and 11.0 disclosed that 2-COOH TM favors the colorless and nonfluorescent lactone form, compared with fluorescein. Substitution of Cl atoms at the 4' and 5' positions of the xanthene moiety of 2-COOH TM to obtain 2-COOH DCTM shifted the equilibrium so that the new derivative exists predominantly in the strongly fluorescent open form at physiological pH (pH 7.4). To demonstrate the practical utility of 2-COOH DCTM as a novel scaffold for red fluorescent probes, we employed it to develop a probe for β-galactosidase.

  13. Sets of RNA repeated tags and hybridization-sensitive fluorescent probes for distinct images of RNA in a living cell.

    Directory of Open Access Journals (Sweden)

    Takeshi Kubota

    Full Text Available BACKGROUND: Imaging the behavior of RNA in a living cell is a powerful means for understanding RNA functions and acquiring spatiotemporal information in a single cell. For more distinct RNA imaging in a living cell, a more effective chemical method to fluorescently label RNA is now required. In addition, development of the technology labeling with different colors for different RNA would make it easier to analyze plural RNA strands expressing in a cell. METHODOLOGY/PRINCIPAL FINDINGS: Tag technology for RNA imaging in a living cell has been developed based on the unique chemical functions of exciton-controlled hybridization-sensitive oligonucleotide (ECHO probes. Repetitions of selected 18-nucleotide RNA tags were incorporated into the mRNA 3'-UTR. Pairs with complementary ECHO probes exhibited hybridization-sensitive fluorescence emission for the mRNA expressed in a living cell. The mRNA in a nucleus was detected clearly as fluorescent puncta, and the images of the expression of two mRNAs were obtained independently and simultaneously with two orthogonal tag-probe pairs. CONCLUSIONS/SIGNIFICANCE: A compact and repeated label has been developed for RNA imaging in a living cell, based on the photochemistry of ECHO probes. The pairs of an 18-nt RNA tag and the complementary ECHO probes are highly thermostable, sequence-specifically emissive, and orthogonal to each other. The nucleotide length necessary for one tag sequence is much shorter compared with conventional tag technologies, resulting in easy preparation of the tag sequences with a larger number of repeats for more distinct RNA imaging.

  14. A two-photon NIR-to-NIR fluorescent probe for imaging hydrogen peroxide in living cells.

    Science.gov (United States)

    Li, Haidong; Yao, Qichao; Fan, Jiangli; Du, Jianjun; Wang, Jingyun; Peng, Xiaojun

    2017-08-15

    Hydrogen peroxide (H 2 O 2 ), one of the reactive oxygen species (ROS), plays vital roles in diverse physiological processes. Imbalance of the H 2 O 2 is concerned with serious diseases such as cardiovascular disorders, neurodegenerative diseases, Alzheimer's disease and cancer. Therefore, it is critical to develop efficient methods for monitoring H 2 O 2 in vivo. In this work, a two-photon excitation (860nm) NIR fluorescent turn-on probe TPNR-H 2 O 2 for H 2 O 2 based on Dicyanomethylene-4H-pyran fluorophore is reported, which can be used in solution detection with 13.2-fold NIR fluorescence enhancement, fast response (completed within 40min), excellent sensitivity (DL 72.48nM), and lower cellular auto-fluorescence interference. Importantly, the perfect photostability of TPNR-H 2 O 2 clearly demonstrated that the probe could be applied to imaging intracellular H 2 O 2 for a long time without photobleaching. In addition, through two-photon imaging, this probe was cell permeable and used to monitor the level of endogenous and exogenous H 2 O 2 with promising biological application. Copyright © 2017. Published by Elsevier B.V.

  15. Fluorescence Detection of Glutathione (GSH) and Oxidized Glutathione (GSSG) in Blood with a NIR-Excitable Cyanine Probe.

    Science.gov (United States)

    Liu, Changhui; Qi, Fengpei; Wen, Fubin; Long, Liping; Yang, Ronghua

    2017-08-17

    Cyanine has been widely utilized as a near infrared (NIR) fluorophore for detection of glutathione (GSH). However, the excitation of most of the reported cyanine-based probes was less than 800 nm, which inevitably induce biological background absorption and lower the sensitivity, limiting their use for detection of GSH in blood samples. To address this issue, here, a heptamethine cyanine probe (DNIR), with a NIR excitation wavelength at 804 nm and a NIR emission wavelength at 832 nm, is employed for the detection of GSH and its oxidized form (GSSG) in blood. The probe displays excellent selectivity for GSH over GSSG and other amino acids (AAs), and rapid response to GSH, in particular a good property for indirect detection of GSSG in the presence of enzyme glutathione reductase (GR) and the reducing agent nicotinamideadenine dinucleotide phosphate (NADPH), without further separation prior to fluorescent measurement. To the best of our knowledge, this is the first attempt to explore NIR fluorescent approach for the simultaneous assay of GSH and GSSG in blood. As such, we expect that our fluorescence sensors with both NIR excitation and NIR emission make this strategy suitable for the application in complex physiological systems. © 2017 IOP Publishing Ltd.

  16. A highly selective turn-on fluorescent probe for Al3+ in aqueous solution based on quinoline Schiff-base

    Science.gov (United States)

    Huang, Peng-Cheng; Fang, Hao; Xiong, Jing-Jing; Wu, Fang-Ying

    2017-06-01

    A new Al3+-specific fluorescent probe NQ was designed and synthesized from 2-hydroxy-1-naphthaldehyde and 2-aminoquinoline. Upon the addition of Al3+, the fluorescent intensity of NQ was significantly enhanced compared with other examined metal ions in aqueous solution. The result of a Job’s plot indicated the formation of a 1:1 complex between the probe and Al3+, and the possible binding mode of the system between NQ and Al3+ was clarified by IR analysis and 1H NMR titration. Moreover, other metal ions examined had little effect on the detection of Al3+. The detection limit of NQ for Al3+ detection was 1.98 μM, which is lower than the level (7.4 μM) in drinking water defined by the World Health Organization. In addition, the fluorescent probe NQ could be recyclable simply through treatment with a proper reagent such as F-, and could also be used for the detection of Al3+ in real samples.

  17. Probing lipid mobility of raft-exhibiting model membranes by fluorescence correlation spectroscopy

    NARCIS (Netherlands)

    Kahya, N; Scherfeld, D; Bacia, K; Poolman, B; Schwille, P

    2003-01-01

    Confocal fluorescence microscopy and fluorescence correlation spectroscopy (FCS) have been employed to investigate the lipid spatial and dynamic organization in giant unilamellar vesicles (GUVs) prepared from ternary mixtures of dioleoyl-phosphatidylcholine/sphingomyelin/ cholesterol. For a certain

  18. Characterisation of corrosion processes of using electron micro-probe, scanning probe microscopy and synchrotron-generated x-ray fluorescence imaging

    International Nuclear Information System (INIS)

    Neufeld, A.K.; Cole, I.S.; Furman, S.A.; Isaacs, H.S.

    2002-01-01

    Full text: With recent advances in computerized technology, the study of chemical reactions can now be visualized as they occur in real time and has resulted in analytical techniques with orders of magnitude greater sensitivity and resolution. This ability offers the corrosion scientist a unique opportunity to study the processes relevant to degradation science which could only be theoretically considered. Neufeld el al (1,2) have attempted to explain in great detail the mechanism of corrosion initiation of zinc by using X-ray micro-probe, Scanning Kelvin probe, and more recently by using synchrotron-generated X-rays and X-ray fluorescence imaging. New results are presented from the synchrotron studies where the transport of ions in-situ has been investigated. The synthesis of information from the techniques will also be discussed in its relevance to atmospheric corrosion processes. Copyright (2002) Australian Society for Electron Microscopy Inc

  19. The cmc-value of a bolalipid with two phosphocholine headgroups and a C24 alkyl chain: Unusual binding properties of fluorescence probes to bolalipid aggregates.

    Science.gov (United States)

    Kordts, Martin; Kerth, Andreas; Drescher, Simon; Ott, Maria; Blume, Alfred

    2017-09-01

    Bolalipids with a long alkyl chain and two phosphocholine polar groups self-assemble in water into two different types of aggregate structures, namely helical nanofibers at low temperature and two types of micellar aggregates at higher temperature. We tried to determine the critical aggregation concentration (cac) or critical micellar concentration (cmc) of the bolalipid tetracosane-1,24-bis(phosphocholine) (PC-C24-PC) by using different fluorescent probes. The use of pyrene or pyrene derivatives as fluorophores failed, whereas the probes 1,8-ANS and particularly bis-ANS gave consistent results. The structure of the bolalipid aggregates obviously hinders partitioning or binding of pyrene derivatives into the micellar interior, whereas 1,8-ANS and bis-ANS can bind to the surface of the aggregate structures. The observed large increase in fluorescence intensity of bis-ANS indicates that binding to the hydrophobic surface of the aggregates leads to a reduction of the dye mobility. However, binding of bis-ANS is relatively weak, so that the determination of a cac/cmc-value is difficult. Simulations of the intensity curves for PC-C24-PC lead to estimates of the cac/cmc-value of 0.3-1.0×10 -6 M, depending on the structure of the aggregates. Single molecule fluorescence correlation spectroscopy was used to determine the mobility of bis-ANS as a function of concentration of PC-C24-PC. The dye diffusion time and the molecular brightness are lower at low bolalipid concentration, when only free dye is present, and increase at higher concentration when bis-ANS is bound to the aggregates. The experimental cac/cmc-values are higher than those estimated, using an incremental method for the change in Gibbs free energy for micellization with n-alkyl-phosphocholines with only one polar group as a comparison. Apparently, for PC-C24-PC in micellar or fibrous aggregates, more CH 2 groups are exposed to water than in a conventional micelle of an n-alkyl-phosphocholine. Copyright

  20. "Clickable" LNA/DNA probes for fluorescence sensing of nucleic acids and autoimmune antibodies

    DEFF Research Database (Denmark)

    Jørgensen, Anna S; Gupta, Pankaj; Wengel, Jesper

    2013-01-01

    Herein we describe fluorescent oligonucleotides prepared by click chemistry between novel alkyne-modified locked nucleic acid (LNA) strands and a series of fluorescent azides for homogeneous (all-in-solution) detection of nucleic acids and autoimmune antibodies.......Herein we describe fluorescent oligonucleotides prepared by click chemistry between novel alkyne-modified locked nucleic acid (LNA) strands and a series of fluorescent azides for homogeneous (all-in-solution) detection of nucleic acids and autoimmune antibodies....

  1. Development of a Novel Fiber Optic Sensor Combined with a Fluorescence Turn-on Probe for Cu (II Detection

    Directory of Open Access Journals (Sweden)

    Ma J.

    2013-04-01

    Full Text Available Existing staining-based methodology for the detection of metal ions is not well suited for real-time or in situ use. This is a significant problem, given that these ions can have a considerable impact on both human health and the environment. Thus, there is growing interest and need for simple, rapid and in-situ monitoring techniques for the purpose of detecting various target analytes (e.g. heavy metals, which is of a significant importance in many fields ranging from environmental monitoring to the study of intracellular processes. Among various sensors developed, optical fiber-optic sensors (FOS, based on fluorescence, are one class of sensors that address this goal [1]. Optical fibers are ideal for environmental sensing applications because of their ability to transmit optical signals to and from the sensing region without the use of free-space optics. In this work, we present, for the first time, a simple FOS incorporating novel fluorescence turn-on mechanism [2] that could detect Cu (II as low as 10−4 M. Traditionally, fluorescence quenching or “turn-off” was used to detect Cu (II [3]. In recent years, fluorescence “turn-on” emerges as a preferable tool. The developed fiber-optic sensor has two fiber leads and one probe head. One fiber lead includes 6 fibers for He-Ne laser excitation light delivery (e-fibers. Another fiber lead has one receiving fiber (r-fiber connected to an Ocean Optics QE65000 scientific grade spectrometer, which is interrogated by a computer via USB connection. The SpectroSuite software is used to observe and to record all spectra. The probe head combines all fibers together to form a coaxial structure with the r-fiber placed in the center. The key component in the proposed fluorescent sensing system is a probe prepared by binding a receptor containing a zwitterionic chromophore (M1, through noncovalent interactions, to the fluorescent polymer (P1 resulting in quenching its emission. The sensing mechanism

  2. A Morphological identification cell cytotoxicity assay using cytoplasm-localized fluorescent probe (CLFP) to distinguish living and dead cells.

    Science.gov (United States)

    Lai, Fangfang; Shen, Zhengwei; Wen, Hui; Chen, Jialing; Zhang, Xiang; Lin, Ping; Yin, Dali; Cui, Huaqing; Chen, Xiaoguang

    2017-01-08

    Cell cytotoxicity assays include cell activity assays and morphological identification assays. Currently, all frequently used cytotoxicity assays belong to cell activity assays but suffer from detection limitations. Morphological identification of cell death remains as the gold standard, although the method is difficult to scale up. At present there is no generally accepted morphological identification based cell cytotoxicity assay. In this study, we applied previous developed cell cytoplasm-localized fluorescent probe (CLFP) to display cell morphologies. Under fluorescence microscopy, the fluorescence morphology and intensity of living cells are distinct from dead cells. Based on these characters we extracted the images of living cells from series of samples via computational analysis. Thus, a novel cell morphological identification cytotoxicity assay (CLFP assay) is developed. The performance of the CLFP assay was similar to cell activity assay (MTT assay), but the accuracy of the CLFP assay was superior when measuring the cytotoxicity of active compounds. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Low-Symmetry Mixed Fluorinated Subphthalocyanines as Fluorescence Imaging Probes in MDA-MB-231 Breast Tumor Cells

    Directory of Open Access Journals (Sweden)

    Katherine J. McAuliffe

    2017-06-01

    Full Text Available Boron subphthalocyanines (SPcs are aromatic macrocycles that possess a combination of physical and optical properties that make them excellent candidates for application as fluorescent imaging probes. These molecules have intense electronic absorption and emission, and structural versatility that allows for specific tuning of physical properties. Herein, we report the synthesis of a series of low-symmetry fluorinated SPcs and compare them to analogous compounds with varying numbers of peripheral fluorine atoms and varied aromaticity. Across the series, with increasing addition of fluorine atoms to the periphery of the ring, a downfield chemical shift in 19F NMR and a bathochromic shift of electronic absorption were observed. Expanding the size of the aromatic ring by replacing peripheral benzo- groups with naphtho- groups prompted a far more drastic bathochromic shift to absorption and emission. Fluorescence quantum yields (Φf proved to be sufficiently high to observe intracellular fluorescence from MDA-MB-231 breast tumor cells in vitro by epifluorescence microscopy; fluorination proved vital for this purpose to improve solubility. This report lays the groundwork for the future development of these promising SPcs for their ultimate application as near-infrared (NIR fluorescent imaging probes in biological systems.

  4. A simple fluorescent probe for the fast sequential detection of copper and biothiols based on a benzothiazole derivative

    Science.gov (United States)

    Shen, Youming; Zhang, Xiangyang; Zhang, Chunxiang; Zhang, Youyu; Jin, Junling; Li, Haitao

    2018-02-01

    A simple benzothiazole fluorescent chemosensor was developed for the fast sequential detection of Cu2 + and biothiols through modulating the excited-state intramolecular proton transfer (ESIPT) process. The compound 1 exhibits highly selective and sensitive fluorescence ;on-off; recognition to Cu2 + with a 1:1 binding stoichiometry by ESIPT hinder. The in situ generated 1-Cu2 + complex can serve as an ;on-off; fluorescent probe for high selectivity toward biothiols via Cu2 + displacement approach, which exerts ESIPT recovery. It is worth pointing out that the 1-Cu2 + complex shows faster for cysteins (within 1 min) than other biothiols such as homocysteine (25 min) and glutathione (25 min). Moreover, the compound 1 displays 160 nm Stoke-shift for reversibly monitoring Cu2 + and biothiols. In addition, the probe is successfully used for fluorescent cellular imaging. This strategy via modulation the ESIPT state has been used for determination of Cu2 + and Cys with satisfactory results, which further demonstrates its value of practical applications.

  5. A convenient colorimetric and ratiometric fluorescent probe for detection of cyanide based on BODIPY derivative in aqueous media

    Directory of Open Access Journals (Sweden)

    Yanhua Yu

    2017-06-01

    Full Text Available A convenient colorimetric and ratiometric fluorescent probe based on BODIPY derivative for cyanide detection has been synthesized, whose structural contains a dicyanovinyl group used as a sensing unit. Among the tested analytes, such as CN−, F−, Cl−, Br−, I−, ClO4−, AcO−, NO3−, H2PO4− HSO4−, S2− and N3−, only CN− could react with dicyanovinyl moiety by nucleophilic addition, which disrupted the π-conjugation of the probe and hindered the intramolecular charge transfer (ICT, leading a blue shift of absorption and fluorescence spectrum and a concomitant color change from yellow to light pink. The detection limit of this probe was calculated to be 0.98 μM, which is lower than the maximum concentration in drinking water (1.9 μM permitted by the World Health Organization (WHO. Moreover, the probe showed excellent selectivity and anti-interference ability towards CN− over other anions. The reaction mechanism was fully supported by 1H NMR and MS spectrum.

  6. Accumulation of polyunsaturated aldehydes in the gonads of the copepod Acartia tonsa revealed by tailored fluorescent probes.

    Directory of Open Access Journals (Sweden)

    Stefanie Wolfram

    Full Text Available Polyunsaturated aldehydes (PUAs are released by several diatom species during predation. Besides other attributed activities, these oxylipins can interfere with the reproduction of copepods, important predators of diatoms. While intensive research has been carried out to document the effects of PUAs on copepod reproduction, little is known about the underlying mechanistic aspects of PUA action. Especially PUA uptake and accumulation in copepods has not been addressed to date. To investigate how PUAs are taken up and interfere with the reproduction in copepods we developed a fluorescent probe containing the α,β,γ,δ-unsaturated aldehyde structure element that is essential for the activity of PUAs as well as a set of control probes. We developed incubation and monitoring procedures for adult females of the calanoid copepod Acartia tonsa and show that the PUA derived fluorescent molecular probe selectively accumulates in the gonads of this copepod. In contrast, a saturated aldehyde derived probe of an inactive parent molecule was enriched in the lipid sac. This leads to a model for PUAs' teratogenic mode of action involving accumulation and covalent interaction with nucleophilic moieties in the copepod reproductive tissue. The teratogenic effect of PUAs can therefore be explained by a selective targeting of the molecules into the reproductive tissue of the herbivores, while more lipophilic but otherwise strongly related structures end up in lipid bodies.

  7. A fusion-spliced near-field optical fiber probe using photonic crystal fiber for nanoscale thermometry based on fluorescence-lifetime measurement of quantum dots.

    Science.gov (United States)

    Fujii, Takuro; Taguchi, Yoshihiro; Saiki, Toshiharu; Nagasaka, Yuji

    2011-01-01

    We have developed a novel nanoscale temperature-measurement method using fluorescence in the near-field called fluorescence near-field optics thermal nanoscopy (Fluor-NOTN). Fluor-NOTN enables the temperature distributions of nanoscale materials to be measured in vivo/in situ. The proposed method measures temperature by detecting the temperature dependent fluorescence lifetimes of Cd/Se quantum dots (QDs). For a high-sensitivity temperature measurement, the auto-fluorescence generated from a fiber probe should be reduced. In order to decrease the noise, we have fabricated a novel near-field optical-fiber probe by fusion-splicing a photonic crystal fiber (PCF) and a conventional single-mode fiber (SMF). The validity of the novel fiber probe was assessed experimentally by evaluating the auto-fluorescence spectra of the PCF. Due to the decrease of auto-fluorescence, a six- to ten-fold increase of S/N in the near-field fluorescence lifetime detection was achieved with the newly fabricated fusion-spliced near-field optical fiber probe. Additionally, the near-field fluorescence lifetime of the quantum dots was successfully measured by the fabricated fusion-spliced near-field optical fiber probe at room temperature, and was estimated to be 10.0 ns.

  8. A Fusion-Spliced Near-Field Optical Fiber Probe Using Photonic Crystal Fiber for Nanoscale Thermometry Based on Fluorescence-Lifetime Measurement of Quantum Dots

    Directory of Open Access Journals (Sweden)

    Toshiharu Saiki

    2011-08-01

    Full Text Available We have developed a novel nanoscale temperature-measurement method using fluorescence in the near-field called Fluorescence Near-field Optics Thermal Nanoscopy (Fluor-NOTN. Fluor-NOTN enables the temperature distributions of nanoscale materials to be measured in vivo/in situ. The proposed method measures temperature by detecting the temperature dependent fluorescence lifetimes of Cd/Se Quantum Dots (QDs. For a high-sensitivity temperature measurement, the auto-fluorescence generated from a fiber probe should be reduced. In order to decrease the noise, we have fabricated a novel near-field optical-fiber probe by fusion-splicing a photonic crystal fiber (PCF and a conventional single-mode fiber (SMF. The validity of the novel fiber probe was assessed experimentally by evaluating the auto-fluorescence spectra of the PCF. Due to the decrease of auto-fluorescence, a six- to ten-fold increase of S/N in the near-field fluorescence lifetime detection was achieved with the newly fabricated fusion-spliced near-field optical fiber probe. Additionally, the near-field fluorescence lifetime of the quantum dots was successfully measured by the fabricated fusion-spliced near-field optical fiber probe at room temperature, and was estimated to be 10.0 ns.

  9. Dansyl-8-aminoquinoline as a sensitive pH fluorescent probe with dual-responsive ranges in aqueous solutions.

    Science.gov (United States)

    Zhang, Min; Zheng, Shuyu; Ma, Liguo; Zhao, Meili; Deng, Lengfang; Yang, Liting; Ma, Li-Jun

    2014-04-24

    A sensitive pH fluorescent probe based on dansyl group, dansyl-8-aminoquinoline (DAQ), has been synthesized. The probe showed dual-responsive ranges to pH changes, one range from 2.00 to 7.95 and another one from 7.95 to 10.87 in aqueous solution, as it showed pKa values of 5.73 and 8.56 under acid and basic conditions, respectively. Furthermore, the pH response mechanism of the probe was explored successfully by using NMR spectra. The results indicated that the responses of DAQ to pH changes should attribute to the protonation of the nitrogen atom in the dimethylamino group and deprotonation of sulfonamide group. Copyright © 2014. Published by Elsevier B.V.

  10. Development of a High-Throughput Fluorescence Polarization Assay to Identify Novel Ligands of Glutamate Carboxypeptidase II

    Czech Academy of Sciences Publication Activity Database

    Alquicer, Glenda; Sedlák, David; Byun, Y.; Pavlíček, Jiří; Stathis, M.; Rojas, C.; Slusher, B.; Pomper, M.G.; Bartůněk, Petr; Bařinka, Cyril

    2012-01-01

    Roč. 17, č. 8 (2012), s. 1030-1040 ISSN 1087-0571 R&D Projects: GA MŠk(CZ) ME10031; GA MŠk(CZ) LC06077 Institutional research plan: CEZ:AV0Z50520701 Institutional support: RVO:68378050 Keywords : fluorescence polarization * glutamate carboxypeptidase II * high-throughput screening Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.207, year: 2012

  11. A fast-response two-photon fluorescent probe for imaging endogenous H2O2 in living cells and tissues

    Science.gov (United States)

    Lu, Yanan; Shi, Xiaomin; Fan, Wenlong; Black, Cory A.; Lu, Zhengliang; Fan, Chunhua

    2018-02-01

    As a second messenger, hydrogen peroxide plays significant roles in numerous physiological and pathological processes and is related to various diseases including inflammatory disease, diabetes, neurodegenerative disorders, cardiovascular disease and Alzheimer's disease. Two-photon (TP) fluorescent probes reported for the detection of endogenous H2O2 are rare and most have drawbacks such as slow response and low sensitivity. In this report, we demonstrate a simple H2O2-specific TP fluorescent probe (TX-HP) containing a two-photon dye 6-hydroxy-2,3,4,4a-tetrahydro-1H-xanthen-1-one (TX) on the modulation of the ICT process. The probe exhibits a rapid fluorescent response to H2O2 in 9 min with both high sensitivity and selectivity. The probe can detect exogenous H2O2 in living cells. Furthermore, the probe is successfully utilized for imaging H2O2 in liver tissues.

  12. Investigation of simultaneously existed Raman scattering enhancement and inhibiting fluorescence using surface modified gold nanostars as SERS probes.

    Science.gov (United States)

    Shan, Feng; Zhang, Xiao-Yang; Fu, Xing-Chang; Zhang, Li-Jiang; Su, Dan; Wang, Shan-Jiang; Wu, Jing-Yuan; Zhang, Tong

    2017-07-28

    One of the main challenges for highly sensitive surface-enhanced Raman scattering (SERS) detection is the noise interference of fluorescence signals arising from the analyte molecules. Here we used three types of gold nanostars (GNSs) SERS probes treated by different surface modification methods to reveal the simultaneously existed Raman scattering enhancement and inhibiting fluorescence behaviors during the SERS detection process. As the distance between the metal nanostructures and the analyte molecules can be well controlled by these three surface modification methods, we demonstrated that the fluorescence signals can be either quenched or enhanced during the detection. We found that fluorescence quenching will occur when analyte molecules are closely contacted to the surface of GNSs, leading to a ~100 fold enhancement of the SERS sensitivity. An optimized Raman signal detection limit, as low as the level of 10 -11  M, were achieved when Rhodamine 6 G were used as the analyte. The presented fluorescence-free GNSs SERS substrates with plentiful hot spots and controllable surface plasmon resonance wavelengths, fabricated using a cost-effective self-assembling method, can be very competitive candidates for high-sensitive SERS applications.

  13. Probing Contaminant-Induced Alterations in Chlorophyll Fluorescence by AC-Dielectrophoresis-Based 2D-Algal Array

    Directory of Open Access Journals (Sweden)

    Coralie Siebman

    2018-02-01

    Full Text Available The investigation of contaminant impact on algae requires rapid and reliable cell collection and optical detection. The capability of alternative current (AC dielectrophoresis (DEP collection of whole cell arrays with combined fluorescence microscopy detection to follow the alterations of chlorophyll fluorescence during environmental contaminant exposure was explored. The application of an AC-field of 100 V cm−1, 100 Hz for 30 min to capture and immobilize the cells of green alga Chlamydomonas reinhardtii in two-dimensional (2D arrays does not induce changes in chlorophyll fluorescence. The results demonstrate that DEP-based 2D-arrays allow non-invasive detection of chlorophyll fluorescence change upon exposure to high concentrations of copper oxide nanoparticles and ionic copper. These results were in agreement with data obtained by flow cytometry used as a comparative method. The tool was also applied to follow the effect of a number of ubiquitous contaminants such as inorganic mercury, methylmercury, and diuron. However, a statistically significant short-term effect was observed only for mercury. Overall, DEP-based 2D-arrays of algal cells with fluorescence detection appear to be suitable for stain-free probing the effects on the photosynthetic microorganisms in highly polluted environment.

  14. Fluorescent probes concentration estimation in vitro and ex vivo as a model for early detection of Alzheimer's disease

    Science.gov (United States)

    Harbater, Osnat; Gannot, Israel

    2014-12-01

    The pathogenic process of Alzheimer's disease (AD) begins years before clinical diagnosis. Here, we suggest a method that may detect AD several years earlier than current exams. The method is based on previous reports that relate the concentration ratio of biomarkers (amyloid-beta and tau) in the cerebrospinal fluid (CSF) to the development of AD. Our method replaces the lumbar puncture process required for CSF drawing by using fluorescence measurements. The system uses an optical fiber coupled to a laser source and a detector. The laser radiation excites two fluorescent probes which may bond to the CSF biomarkers. Their concentration ratio is extracted from the fluorescence intensities and can be used for future AD detection. First, we present a theoretical model for fluorescence concentration ratio estimation. The method's feasibility was validated using Monte Carlo simulations. Its accuracy was then tested using multilayered tissue phantoms simulating the epidural fat, CSF, and bone. These phantoms have various optical properties, thicknesses, and fluorescence concentrations in order to simulate human anatomy variations and different fiber locations. The method was further tested using ex vivo chicken tissue. The average errors of the estimated concentration ratios were low both in vitro (4.4%) and ex vivo (10.9%), demonstrating high accuracy.

  15. Synthesis of water-soluble, ring-substituted squaraine dyes and their evaluation as fluorescent probes and labels

    International Nuclear Information System (INIS)

    Tatarets, Anatoliy L.; Fedyunyayeva, Irina A.; Dyubko, Tatyana S.; Povrozin, Yevgeniy A.; Doroshenko, Andrey O.; Terpetschnig, Ewald A.; Patsenker, Leonid D.

    2006-01-01

    A series of ring-substituted squaraines absorbing and emitting in the red and NIR spectral region was synthesized and their spectral and photophysical properties (quantum yields, fluorescence lifetimes) and photostabilities were measured and compared to Cy5, a commonly used fluorescent label. The absorption maxima in aqueous media were found to be between 628 and 667 nm and the emission maxima are between 642 and 685 nm. Squaraine dyes exhibit high extinction coefficients (163,000-265,000 M -1 cm -1 ) and lower quantum yields (2-7%) in aqueous buffer but high quantum yields (up to 45%) and long fluorescence lifetimes (up to 3.3 ns) in presence of BSA. Dicyanomethylene- and thio-substituted squaraines exhibit an additional absorption around 400 nm with extinction coefficients between 21,500 and 44,500 M -1 cm -1 . These dyes are excitable not only with red but also with blue diode lasers or light emitting diodes. Due to the favourable spectral and photophysical properties these dyes can be used as fluorescent probes and labels for intensity- and fluorescence lifetime-based biomedical applications

  16. A highly selective turn-on fluorescent probe for hypochlorous acid based on hypochlorous acid-induced oxidative intramolecular cyclization of boron dipyrromethene-hydrazone

    International Nuclear Information System (INIS)

    Chen, Wei-Chieh; Venkatesan, Parthiban; Wu, Shu-Pao

    2015-01-01

    Highlights: • A BODIPY-based fluorescent probe for sensing HOCl was developed. • The probe utilizes the HOCl-promoted cyclization in response to the amount of HOCl. • The probe might have application in the investigation of HOCl in biological systems. - Abstract: A BODIPY-based fluorescent probe, HBP, was developed for the detection of hypochlorous acid based on the specific hypochlorous acid-promoted oxidative intramolecular cyclization of heterocyclic hydrazone in response to the amount of HOCl. The reaction is accompanied by a 41-fold increase in the fluorescent quantum yield (from 0.004 to 0.164). The fluorescence intensity of the reaction between HOCl and HBP is linear in the HOCl concentration range of 1–8 μM with a detection limit of 2.4 nM (S/N = 3). Confocal fluorescence microscopy imaging using RAW264.7 cells showed that the new probe HBP could be used as an effective fluorescent probe for detecting HOCl in living cells

  17. A lysosome-locating and acidic pH-activatable fluorescent probe for visualizing endogenous H2O2 in lysosomes.

    Science.gov (United States)

    Liu, Jun; Zhou, Shunqing; Ren, Jing; Wu, Chuanliu; Zhao, Yibing

    2017-11-20

    There is increasing evidence indicating that lysosomal H 2 O 2 is closely related to autophagy and apoptotic pathways under both physiological and pathological conditions. Therefore, fluorescent probes that can be exploited to visualize H 2 O 2 in lysosomes are potential tools for exploring diverse roles of H 2 O 2 in cells. However, functional exploration of lysosomal H 2 O 2 is limited by the lack of fluorescent probes capable of compatibly sensing H 2 O 2 under weak acidic conditions (pH = 4.5) of lysosomes. Lower spatial resolution of the fluorescent visualization of lysosomal H 2 O 2 might be caused by the interference of signals from cytosolic and mitochondrial H 2 O 2 , as well as the non-specific distribution of the probes in cells. In this work, we developed a lysosome-locating and acidic-pH-activatable fluorescent probe for the detection and visualization of H 2 O 2 in lysosomes, which consists of a H 2 O 2 -responsive boronate unit, a lysosome-locating morpholine group, and a pH-activatable benzorhodol fluorophore. The response of the fluorescent probe to H 2 O 2 is significantly more pronounced under acidic pH conditions than that under neutral pH conditions. Notably, the present probe enables the fluorescence sensing of endogenous lysosomal H 2 O 2 in living cells without external stimulations, with signal interference from the cytoplasm and other intracellular organelles being negligible.

  18. Rhodamine-labeled 2beta-carbomethoxy-3beta-(3,4-dichlorophenyl)tropane analogues as high-affinity fluorescent probes for the dopamine transporter

    DEFF Research Database (Denmark)

    Cha, Joo Hwan; Zou, Mu-Fa; Adkins, Erika M

    2005-01-01

    Novel fluorescent ligands were synthesized to identify a high-affinity probe that would enable visualization of the dopamine transporter (DAT) in living cells. Fluorescent tags were extended from the N- or 2-position of 2beta-carbomethoxy-3beta-(3,4-dichlorophenyl)tropane, using an ethylamino lin...

  19. Investigations on therapeutic glucocerebrosidases through paired detection with fluorescent activity-based probes.

    Directory of Open Access Journals (Sweden)

    Wouter W Kallemeijn

    Full Text Available Deficiency of glucocerebrosidase (GBA causes Gaucher disease (GD. In the common non-neuronopathic GD type I variant, glucosylceramide accumulates primarily in the lysosomes of visceral macrophages. Supplementing storage cells with lacking enzyme is accomplished via chronic intravenous administration of recombinant GBA containing mannose-terminated N-linked glycans, mediating the selective uptake by macrophages expressing mannose-binding lectin(s. Two recombinant GBA preparations with distinct N-linked glycans are registered in Europe for treatment of type I GD: imiglucerase (Genzyme, contains predominantly Man(3 glycans, and velaglucerase (Shire PLC Man(9 glycans. Activity-based probes (ABPs enable fluorescent labeling of recombinant GBA preparations through their covalent attachment to the catalytic nucleophile E340 of GBA. We comparatively studied binding and uptake of ABP-labeled imiglucerase and velaglucerase in isolated dendritic cells, cultured human macrophages and living mice, through simultaneous detection of different GBAs by paired measurements. Uptake of ABP-labeled rGBAs by dendritic cells was comparable, as well as the bio-distribution following equimolar intravenous administration to mice. ABP-labeled rGBAs were recovered largely in liver, white-blood cells, bone marrow and spleen. Lungs, brain and skin, affected tissues in severe GD types II and III, were only poorly supplemented. Small, but significant differences were noted in binding and uptake of rGBAs in cultured human macrophages, in the absence and presence of mannan. Mannan-competed binding and uptake were largest for velaglucerase, when determined with single enzymes or as equimolar mixtures of both enzymes. Vice versa, imiglucerase showed more prominent binding and uptake not competed by mannan. Uptake of recombinant GBAs by cultured macrophages seems to involve multiple receptors, including several mannose-binding lectins. Differences among cells from different donors

  20. Counting and Size Classification of Active Soil Bacteria by Fluorescence In Situ Hybridization with an rRNA Oligonucleotide Probe

    Science.gov (United States)

    Christensen, Henrik; Hansen, Michael; Sørensen, Jan

    1999-01-01

    A fluorescence in situ hybridization (FISH) technique based on binding of a rhodamine-labelled oligonucleotide probe to 16S rRNA was used to estimate the numbers of ribosome-rich bacteria in soil samples. Such bacteria, which have high cellular rRNA contents, were assumed to be active (and growing) in the soil. Hybridization to an rRNA probe, EUB338, for the domain Bacteria was performed with a soil slurry, and this was followed by collection of the bacteria by membrane filtration (pore size, 0.2 μm). A nonsense probe, NONEUB338 (which has a nucleotide sequence complementary to the nucleotide sequence of probe EUB338), was used as a control for nonspecific staining. Counting and size classification into groups of small, medium, and large bacteria were performed by fluorescence microscopy. To compensate for a difference in the relative staining intensities of the probes and for binding by the rhodamine part of the probe, control experiments in which excess unlabelled probe was added were performed. This resulted in lower counts with EUB338 but not with NONEUB338, indicating that nonspecific staining was due to binding of rhodamine to the bacteria. A value of 4.8 × 108 active bacteria per g of dry soil was obtained for bulk soil incubated for 2 days with 0.3% glucose. In comparison, a value of 3.8 × 108 active bacteria per g of dry soil was obtained for soil which had been air dried and subsequently rewetted. In both soils, the majority (68 to 77%) of actively growing bacteria were members of the smallest size class (cell width, 0.25 to 0.5 μm), but the active (and growing) bacteria still represented only approximately 5% of the total bacterial population determined by DAPI (4′,6-diamidino-2-phenylindole) staining. The FISH technique in which slurry hybridization is used holds great promise for use with phylogenetic probes and for automatic counting of soil bacteria. PMID:10103277

  1. Polarization Effects in Graded AlGaN Nanolayers Revealed by Current-Sensing and Kelvin Probe Microscopy.

    Science.gov (United States)

    Lytvyn, Petro M; Kuchuk, Andrian V; Mazur, Yuriy I; Li, Chen; Ware, Morgan E; Wang, Zhiming M; Kladko, Vasyl P; Belyaev, Alexander E; Salamo, Gregory J

    2018-02-21

    We experimentally demonstrate that the conductivity of graded Al x Ga 1-x N increases as a function of the magnitude of the Al concentration gradient (%Al/nm) due to polarization doping effects, without the use of impurity dopants. Using three up/down-graded Al x Ga 1-x N nanolayers with Al gradients ranging from ∼0.16 to ∼0.28%Al/nm combined in one structure, the effects of polarization engineering for localized electric fields and current transport were investigated. Cross-sectional Kelvin probe force microscopy and conductive atomic force microscopy were used to directly probe the electrical properties of the films with spatial resolution along the thickness of the growth. The experimental profiles of the built-in electric fields and the spreading current found in the graded layers are shown to be consistent with simulations of the field distribution as well as of the electron and hole densities. Finally, it was directly observed that for gradients less than 0.28%Al/nm the native n-type donors still limit polarization-induced hole doping, making p-type conductivity still a challenge due to background impurities and defects.

  2. A dual mode targeting probe for distinguishing HER2-positive breast cancer cells using silica-coated fluorescent magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jia [Medical School Southeast University, Department of Ultrasonography, Zhongda Hospital (China); An, Yan-Li; Zang, Feng-Chao [Southeast University, Jiangsu Key Laboratory of Molecular and Functional Imaging (China); Zong, Shen-Fei; Cui, Yi-Ping, E-mail: cyp@seu.edu.cn [Southeast University, Advanced Photonics Center (China); Teng, Gao-Jun, E-mail: gjteng@vip.sina.com [Southeast University, Jiangsu Key Laboratory of Molecular and Functional Imaging (China)

    2013-10-15

    We report a composite nanoprobe based on silica-coated magnetic nanoparticles (NPs) for distinguishing breast cancers at different HER2 statuses. The nanoprobe has a core-shell structure, with Fe{sub 3}O{sub 4} NPs as the magnetic core and dye-embedded silica as the fluorescent shell, whose average size is about 150 nm. Besides, the outmost surfaces of the probes were modified with specific antibodies to endow the probe with a targeting ability. With such a structure, the nanoprobe can accomplish dual mode targeting of human breast cancer cells based on fluorescence and magnetic resonance imaging (MRI). In the experiments, three human breast cancer cell lines were used to test the targeting ability of the nanoprobe. Specifically, SKBR3 cells with a high HER2 expression level were used as the model target cells, while MCF7 cells with a lower HER2 expression levels and HER2-negative MDA-MB-231 cells were used as the controls. Both the fluorescence and MRI imaging results confirmed that the nanoprobe can distinguish three cancer cell lines with different HER2 expression levels. With the dual mode imaging and specific targeting properties, we anticipate that the presented nanoprobe may have a great potential in the diagnosis and treatment of cancerous diseases.

  3. A dual mode targeting probe for distinguishing HER2-positive breast cancer cells using silica-coated fluorescent magnetic nanoparticles

    Science.gov (United States)

    Li, Jia; An, Yan-Li; Zang, Feng-Chao; Zong, Shen-Fei; Cui, Yi-Ping; Teng, Gao-Jun

    2013-10-01

    We report a composite nanoprobe based on silica-coated magnetic nanoparticles (NPs) for distinguishing breast cancers at different HER2 statuses. The nanoprobe has a core-shell structure, with Fe3O4 NPs as the magnetic core and dye-embedded silica as the fluorescent shell, whose average size is about 150 nm. Besides, the outmost surfaces of the probes were modified with specific antibodies to endow the probe with a targeting ability. With such a structure, the nanoprobe can accomplish dual mode targeting of human breast cancer cells based on fluorescence and magnetic resonance imaging (MRI). In the experiments, three human breast cancer cell lines were used to test the targeting ability of the nanoprobe. Specifically, SKBR3 cells with a high HER2 expression level were used as the model target cells, while MCF7 cells with a lower HER2 expression levels and HER2-negative MDA-MB-231 cells were used as the controls. Both the fluorescence and MRI imaging results confirmed that the nanoprobe can distinguish three cancer cell lines with different HER2 expression levels. With the dual mode imaging and specific targeting properties, we anticipate that the presented nanoprobe may have a great potential in the diagnosis and treatment of cancerous diseases.

  4. A turn-on supramolecular fluorescent probe for sensing benzimidazole fungicides and its application in living cell imaging

    Science.gov (United States)

    Tang, Qing; Zhang, Jing; Sun, Tao; Wang, Cheng-Hui; Huang, Ying; Zhou, Qingdi; Wei, Gang

    2018-02-01

    A cucurbit[8]uril-based turn-on supramolecular fluorescent probe between cucurbit[8]uril (Q[8]) and pyronine Y (PyY) (designated 2PyY@Q[8]) in acidic aqueous solution showed a remarkable fluorescence 'turn-on' response to benzimidazole fungicides such as thiabendazole, fuberidazole and carbendazim. The 2PyY@Q[8] fluorescent probe can be used to detect benzimidazole fungicides with high sensitivity and selectivity with a detection limit of 10- 8 mol/L. A good linear relationship of emission intensity at 580 nm for benzimidazole fungicides at concentrations of 0.4-5.0 μmol/L was observed. The proposed sensing mechanism was investigated using 1H NMR spectroscopy combined with density functional theory calculations at the B3LYP/6-31G(d) level. The cell imaging study showed that the 2PyY@Q[8] complex could be used to image benzimidazole fungicide in prostate cancer (PC3) cells, which may help to elucidate relevant biological processes at the molecular level.

  5. o-Fluorination of aromatic azides yields improved azido-based fluorescent probes for hydrogen sulfide: synthesis, spectra, and bioimaging.

    Science.gov (United States)

    Wei, Chao; Wang, Runyu; Wei, Lv; Cheng, Longhuai; Li, Zhifei; Xi, Zhen; Yi, Long

    2014-12-01

    Hydrogen sulfide (H2S) is an endogenously produced gaseous signaling molecule with multiple biological functions. To visualize the endogenous in situ production of H2S in real time, new coumarin- and boron-dipyrromethene-based fluorescent turn-on probes were developed for fast sensing of H2S in aqueous buffer and in living cells. Introduction of a fluoro group in the ortho position of the aromatic azide can lead to a greater than twofold increase in the rate of reaction with H2S. On the basis of o-fluorinated aromatic azides, fluorescent probes with high sensitivity and selectivity toward H2S over other biologically relevant species were designed and synthesized. The probes can be used to in situ to visualize exogenous H2S and D-cysteine-dependent endogenously produced H2S in living cells, which makes them promising tools for potential applications in H2S biology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. TaqMan MGB probe fluorescence real-time quantitative PCR for rapid detection of Chinese Sacbrood virus.

    Directory of Open Access Journals (Sweden)

    Ma Mingxiao

    Full Text Available Sacbrood virus (SBV is a picorna-like virus that affects honey bees (Apis mellifera and results in the death of the larvae. Several procedures are available to detect Chinese SBV (CSBV in clinical samples, but not to estimate the level of CSBV infection. The aim of this study was develop an assay for rapid detection and quantification of this virus. Primers and probes were designed that were specific for CSBV structural protein genes. A TaqMan minor groove binder (MGB probe-based, fluorescence real-time quantitative PCR was established. The specificity, sensitivity and stability of the assay were assessed; specificity was high and there were no cross-reactivity with healthy larvae or other bee viruses. The assay was applied to detect CSBV in 37 clinical samples and its efficiency was compared with clinical diagnosis, electron microscopy observation, and conventional RT-PCR. The TaqMan MGB-based probe fluorescence real-time quantitative PCR for CSBV was more sensitive than other methods tested. This assay was a reliable, fast, and sensitive method that was used successfully to detect CSBV in clinical samples. The technology can provide a useful tool for rapid detection of CSBV. This study has established a useful protocol for CSBV testing, epidemiological investigation, and development of animal models.

  7. New fluorescent probes of the hydroxyl radical: characterisation and modelization of the reactivity of coumarin derivatives with HO

    International Nuclear Information System (INIS)

    Louit, G.

    2005-10-01

    The hydroxyl radical is involved in a wide range of different fields, from oxidative stress to atmospheric chemistry. In addition to the study of oxidative damage in biological media, the hydroxyl radical detection allows to perform a dosimetry when it is produced by ionising radiation. The aims of this work have been double: - to improve the detection of the hydroxyl radical by the design of new probes - to improve knowledge on the reactive pathways in which the hydroxyl radical is involved. We have studied the coumarin molecule, as well as 6 derivatives that we have synthesised, as fluorescent probes of the hydroxyl radical. Firstly, fluorescence spectroscopy and HPLC chromatography have allowed the evaluation of the sensibility and selectivity of detection of the probes. Consequently to this study, two applications have been developed, concerning the determination of rate constants by competition kinetics and bidimensional dosimetry. Secondly, we have studied the reactivity of the hydroxyl radical through the regioselectivity of its addition on the aromatic cycle. This problem was addressed by the combined use of experimental methods such as time resolved kinetics and HPLC along with interpretation from classical and ab initio modelization. (author)

  8. Probing the Accretion Geometry of Black Holes with X-Ray Polarization

    Science.gov (United States)

    Schnitman, Jeremy D.

    2011-01-01

    In the coming years, new space missions will be able to measure X-ray polarization at levels of 1% or better in the approx.1-10 keV energy band. In particular, X-ray polarization is an ideal tool for determining the nature of black hole (BH) accretion disks surrounded by hot coronae. Using a Monte Carlo radiation transport code in full general relativity, we calculate the spectra and polarization features of these BH systems. At low energies, the signal is dominated by the thermal flux coming directly from the optically thick disk. At higher energies, the thermal seed photons have been inverse-Compton scattered by the corona, often reflecting back off the disk before reaching the observer, giving a distinctive polarization signature. By measuring the degree and angle of this X-ray polarization, we can infer the BH inclination, the emission geometry of the accretion flow, and also determine the spin of the black hole.

  9. Investigation of the Stability of the Ruthenium based Dye (N719) Utilizing the Polarization Properties of Dispersive Raman Modes and/or of the Fluorescent Emission

    DEFF Research Database (Denmark)

    Hassing, Søren; Jernshøj, Kit Drescher; Phuong, Nguyen

    2013-01-01

    for short) is possible by exploiting a combination of the polarization properties of the dispersive Raman modes with the small spectral change in the visible absorption spectrum and/or the difference in the polarization of the fluorescence related to the difference in molecular configuration. By measuring...

  10. Magnetically engineered Cd-free quantum dots as dual-modality probes for fluorescence/magnetic resonance imaging of tumors.

    Science.gov (United States)

    Ding, Ke; Jing, Lihong; Liu, Chunyan; Hou, Yi; Gao, Mingyuan

    2014-02-01

    Magnetically engineered Cd-free CuInS2@ZnS:Mn quantum dots (QDs) were designed, synthesized, and evaluated as potential dual-modality probes for fluorescence and magnetic resonance imaging (MRI) of tumors in vivo. The synthesis of Mn-doped core-shell structured CuInS2@ZnS mainly comprised three steps, i.e., the preparation of fluorescent CuInS2 seeds, the particle surface coating of ZnS, and the Mn-doping of the ZnS shells. Systematic spectroscopy studies were carried out to illustrate the impacts of ZnS coating and the following Mn-doping on the optical properties of the QDs. In combination with conventional fluorescence, fluorescence excitation, and time-resolved fluorescence measurements, the structure of CuInS2@ZnS:Mn QDs prepared under optimized conditions presented a Zn gradient CuInS2 core and a ZnS outer shell, while Mn ions were mainly located in the ZnS shell, which well balanced the optical and magnetic properties of the resultant QDs. For the following in vivo imaging experiments, the hydrophobic CuInS2@ZnS:Mn QDs were transferred into water upon ligand exchange reactions by replacing the 1-dodecanethiol ligand with dihydrolipoic acid-poly(ethylene glycol) (DHLA-PEG) ligand. The MTT assays based on HeLa cells were carried out to evaluate the cytotoxicity of the current Cd-free CuInS2@ZnS:Mn QDs for comparing with that of water soluble CdTe QDs. Further in vivo fluorescence and MR imaging experiments suggested that the PEGylated CuInS2@ZnS:Mn QDs could well target both subcutaneous and intraperitoneal tumors in vivo. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Sensitive and rapid detection of endogenous hydrogen sulfide distributing in different mouse viscera via a two-photon fluorescent probe

    International Nuclear Information System (INIS)

    Chen, Qian; Yang, Jinfeng; Li, Yinhui; Zheng, Jing; Yang, Ronghua

    2015-01-01

    Development of efficient methods for detection of endogenous H 2 S in living cells and tissues is of considerable significance for better understanding the biological and pathological functions of H 2 S. Two-photon (TP) fluorescent probes are favorable as powerful molecular tools for studying physiological process due to its non-invasiveness, high spatiotemporal resolution and deep-tissues imaging. Up to date, several TP probes for intracellular H 2 S imaging have been designed, but real-time imaging of endogenous H 2 S-related biological processes in tissues is hampered due to low sensitivity, long response time and interference from other biothiols. To address this issue, we herein report a novel two-photon fluorescent probe (TPP-H 2 S) for highly sensitive and fast monitoring and imaging H 2 S levels in living cells and tissues. In the presence of H 2 S, it exhibits obviously improved sensitivity (LOD: 0.12 μM) and fast response time (about 2 min) compared with the reported two-photon H 2 S probes. With two-photon excitation, TPP-H 2 S displays high signal-to-noise ratio and sensitivity even no interference in cell growth media. As further application, TPP-H 2 S is applied for fast imaging of H 2 S in living cells and different fresh tissues by two-photon confocal microscope. Most importantly we first measured the endogenous H 2 S level in different viscera by vivisection and found that the distribution of endogenous H 2 S mostly in brain, liver and lung. The excellent sensing properties of TPP-H 2 S make it a practically useful tool for further studying biological roles of H 2 S. - Highlights: • This two-photon probe exhibits an improved sensitivity and response time to H 2 S. • This probe shows excellent membrane permeability and fast visualization of H 2 S in living cells and tissues. • This probe is successfully applied to measure the endogenously produced H 2 S levels in different viscera of mouse.

  12. Sensitive and rapid detection of endogenous hydrogen sulfide distributing in different mouse viscera via a two-photon fluorescent probe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qian [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Yang, Jinfeng [Tumor Hospital, Xiangya School of Medicine, Central South University, Changsha, 410013 (China); Li, Yinhui, E-mail: yinhuili16@163.com [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Zheng, Jing [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Yang, Ronghua, E-mail: yangrh@pku.edu.cn [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); School of Chemistry and Biological Engineering, Changsha University of Science and Technology, Changsha, 410004 (China)

    2015-10-08

    Development of efficient methods for detection of endogenous H{sub 2}S in living cells and tissues is of considerable significance for better understanding the biological and pathological functions of H{sub 2}S. Two-photon (TP) fluorescent probes are favorable as powerful molecular tools for studying physiological process due to its non-invasiveness, high spatiotemporal resolution and deep-tissues imaging. Up to date, several TP probes for intracellular H{sub 2}S imaging have been designed, but real-time imaging of endogenous H{sub 2}S-related biological processes in tissues is hampered due to low sensitivity, long response time and interference from other biothiols. To address this issue, we herein report a novel two-photon fluorescent probe (TPP-H{sub 2}S) for highly sensitive and fast monitoring and imaging H{sub 2}S levels in living cells and tissues. In the presence of H{sub 2}S, it exhibits obviously improved sensitivity (LOD: 0.12 μM) and fast response time (about 2 min) compared with the reported two-photon H{sub 2}S probes. With two-photon excitation, TPP-H{sub 2}S displays high signal-to-noise ratio and sensitivity even no interference in cell growth media. As further application, TPP-H{sub 2}S is applied for fast imaging of H{sub 2}S in living cells and different fresh tissues by two-photon confocal microscope. Most importantly we first measured the endogenous H{sub 2}S level in different viscera by vivisection and found that the distribution of endogenous H{sub 2}S mostly in brain, liver and lung. The excellent sensing properties of TPP-H{sub 2}S make it a practically useful tool for further studying biological roles of H{sub 2}S. - Highlights: • This two-photon probe exhibits an improved sensitivity and response time to H{sub 2}S. • This probe shows excellent membrane permeability and fast visualization of H{sub 2}S in living cells and tissues. • This probe is successfully applied to measure the endogenously produced H{sub 2}S levels in

  13. Fluorescence of the gamma, epsilon, and delta systems of nitric oxide - Polarization and use of calculated intensities for spectrometer calibration.

    Science.gov (United States)

    Poland, H. M.; Broida, H. P.

    1971-01-01

    Results of a study in which fluorescence of the gamma system of nitric oxide was obtained by excitation from both the 2144 A line of ionized cadmium and a continuum source. Individual rotational lines of the 2144 A excited fluorescence spectrum were found to be partially polarized and to have polarizations of differ ing sign. Measured relative vibrational band intensities from line and continuum excitation were compared to calculated Franck-Condon factors. Those Franck-Condon factors based on a single potential for the two spin states of the X super pi state agreed better with measured values than those based on separate potentials for the two spin states. Calculated intensities of the v prime = 3 progression were used to calibrate the instrument response in the wavelength region from 2000 to 2500 A and were checked with measured intensities of the v prime = 0.1, and 2 progressions. Fluorescence of the epsilon and delta bands obtained with continuum lamp excitation also were compared to calculated intensities.

  14. Exploring metal detoxification and accumulation potential during vermicomposting of Tea factory coal ash: sequential extraction and fluorescence probe analysis

    Science.gov (United States)

    Goswami, Linee; Pratihar, Sanjay; Dasgupta, Suman; Bhattacharyya, Pradip; Mudoi, Pronab; Bora, Jayanta; Bhattacharya, Satya Sundar; Kim, Ki Hyun

    2016-07-01

    Metal contamination from coal ashes (CAs) is widely recognized as a significant environmental concern. To learn more about metal detoxification and accumulation potential of earthworm species, metal-rich tea factory coal ashes (TFCA) were fed to Eisenia fetida and Lampito mauritii by employing a fluorescent tag detection method. Fascinatingly, on feeding fluorescence probed Zn and Cd along with cow dung to Eisenia fetida, the detection of the gut-proteins with a molecular mass higher than 100 kDa was a distinct evidence of metal binding. Significant increases were observed in the content of humified organic C [humic acid (HAC) and fulvic acid C (FAC)] and degree of humification during vermicomposting. Concurrently, considerably large amount of toxic metals (Cr, Cd, Pb, and Zn) was transformed from exchangeable to recalcitrant (organic matter and mineral bound) fractions. Moreover, total metal concentrations were reduced with high removal efficiency upon vermicomposting.

  15. On measurement of top polarization as a probe of $t \\bar t$ production mechanisms at the LHC

    CERN Document Server

    Godbole, Rohini M; Rindani, Saurabh D; Singh, Ritesh K

    2010-01-01

    In this note we demonstrate the use of top polarization in the study of $t \\bar t$ resonances at the LHC, in the possible case where the dynamics implies a non-zero top polarization. As a probe of top polarization we construct an asymmetry in the decay-lepton azimuthal angle distribution (corresponding to the sign of $\\cos\\phi_\\ell$) in the laboratory. The asymmetry is non-vanishing even for a symmetric collider like the LHC, where a positive $z$ axis is not uniquely defined. The angular distribution of the leptons has the advantage of being a faithful top-spin analyzer, unaffected by possible anomalous $tbW$ couplings, to linear order. We study, for purposes of demonstration, the case of a $Z'$ as might exist in the little Higgs models. We identify kinematic cuts which ensure that our asymmetry reflects the polarization in sign and magnitude. We investigate possibilities at the LHC with two energy options: $\\sqrt{s} = 14$ TeV and $\\sqrt{s} = 7$ TeV, as well as at the Tevatron. At the LHC the model predicts n...

  16. A novel “Turn-On” fluorescent probe for F− detection in aqueous solution and its application in live-cell imaging

    International Nuclear Information System (INIS)

    Xu, Jian; Sun, Shaobo; Li, Qian; Yue, Ying; Li, Yingdong; Shao, Shijun

    2014-01-01

    Highlights: • A novel BODIPY-based “Turn-On” fluorescent probe was synthesized. • Highly selective detection of fluoride ions in 100% aqueous solution. • Study of sensing mechanism using density functional theory (DFT) calculations. • Fluorescent bioimaging of F − ion in A549 and ATII cells. - Abstract: A novel probe incorporating quaternized 4-pyridinium group into a BODIPY molecule was synthesized and studied for the selective detection of fluoride ions (F − ) in aqueous solution. The design was based on a fluoride-specific desilylation reaction and the “Turn-On” fluorescent response of probe 1 to F − was ascribed to the inhibition of photoinduced electron transfer (PET) process. The probe displayed many desired properties such as high specificity, appreciable solubility, desirable response time and low toxicity to mammalian cells. There was a good linearity between the fluorescence intensity and the concentrations of F − in the range of 0.1–1 mM with a detection limit of 0.02 mM. The sensing mechanism was confirmed by the NMR, electrospray ionization mass spectrum, optical spectroscopy and the mechanism of “Turn-On” fluorescent response was also determinated by a density functional theory (DFT) calculation using Gaussian 03 program. Moreover, the probe was successfully applied for the fluorescence imaging of F − in human epithelial lung cancer (A549) cells and alveolar type II (ATII) cells under physiological conditions

  17. A novel “Turn-On” fluorescent probe for F{sup −} detection in aqueous solution and its application in live-cell imaging

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jian [Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Sun, Shaobo [Institute of Integrated Traditional and Western Medicine, Gansu University of Chinese Medicine, Lanzhou 730000 (China); Li, Qian; Yue, Ying [Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Yingdong [Institute of Integrated Traditional and Western Medicine, Gansu University of Chinese Medicine, Lanzhou 730000 (China); Shao, Shijun, E-mail: sjshao@licp.cas.cn [Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2014-11-07

    Highlights: • A novel BODIPY-based “Turn-On” fluorescent probe was synthesized. • Highly selective detection of fluoride ions in 100% aqueous solution. • Study of sensing mechanism using density functional theory (DFT) calculations. • Fluorescent bioimaging of F{sup −} ion in A549 and ATII cells. - Abstract: A novel probe incorporating quaternized 4-pyridinium group into a BODIPY molecule was synthesized and studied for the selective detection of fluoride ions (F{sup −}) in aqueous solution. The design was based on a fluoride-specific desilylation reaction and the “Turn-On” fluorescent response of probe 1 to F{sup −} was ascribed to the inhibition of photoinduced electron transfer (PET) process. The probe displayed many desired properties such as high specificity, appreciable solubility, desirable response time and low toxicity to mammalian cells. There was a good linearity between the fluorescence intensity and the concentrations of F{sup −} in the range of 0.1–1 mM with a detection limit of 0.02 mM. The sensing mechanism was confirmed by the NMR, electrospray ionization mass spectrum, optical spectroscopy and the mechanism of “Turn-On” fluorescent response was also determinated by a density functional theory (DFT) calculation using Gaussian 03 program. Moreover, the probe was successfully applied for the fluorescence imaging of F{sup −} in human epithelial lung cancer (A549) cells and alveolar type II (ATII) cells under physiological conditions.

  18. Ultrafast Dynamics of Sb-Corroles: A Combined Vis-Pump Supercontinuum Probe and Broadband Fluorescence Up-Conversion Study

    Directory of Open Access Journals (Sweden)

    Clark Zahn

    2017-07-01

    Full Text Available Corroles are a developing class of tetrapyrrole-based molecules with significant chemical potential and relatively unexplored photophysical properties. We combined femtosecond broadband fluorescence up-conversion and fs broadband Vis-pump Vis-probe spectroscopy to comprehensively characterize the photoreaction of 5,10,15-tris-pentafluorophenyl-corrolato-antimony(V-trans-difluoride (Sb-tpfc-F2. Upon fs Soret band excitation at ~400 nm, the energy relaxed almost completely to Q band electronic excited states with a time constant of 500 ± 100 fs; this is evident from the decay of Soret band fluorescence at around 430 nm and the rise time of Q band fluorescence, as well as from Q band stimulated emission signals at 600 and 650 nm with the same time constant. Relaxation processes on a time scale of 10 and 20 ps were observed in the fluorescence and absorption signals. Triplet formation showed a time constant of 400 ps, with an intersystem crossing yield from the Q band to the triplet manifold of between 95% and 99%. This efficient triplet formation is due to the spin-orbit coupling of the antimony ion.

  19. Carbon dots as fluorescent probes for "off-on" detection of Cu2+ and L-cysteine in aqueous solution.

    Science.gov (United States)

    Zong, Jie; Yang, Xiaoling; Trinchi, Adrian; Hardin, Simon; Cole, Ivan; Zhu, Yihua; Li, Chunzhong; Muster, Tim; Wei, Gang

    2014-01-15

    Copper ion (Cu(2+)) and L-cysteine (L-Cys) detection is critically important since an abnormal level of Cu(2+) or L-Cys is an indicator for many diseases. In this paper, we demonstrate an "off-on" approach for highly sensitive and selective detection of Cu(2+) and L-Cys using carbon dots (CDs) as fluorescent probes. CDs were prepared by using mesoporous silica (MS) spheres as nanoreactors. The binding ability of CDs towards metal ions was examined by comparing the fluorescence intensities of CDs before and after the addition of the metal ions. The addition of Cu(2+) cations leads to their absorption on the surface of CDs and the significant fluorescence quench of CDs (turn-off). The resulting in CDs-Cu(2+) system was found to be sensitive to L-Cys. The addition of L-Cys not only serves to shelter the CDs effectively from being quenched, but also to reverse the quenching and restore the fluorescence (turn-on) due to its ability to remove Cu(2+) from the surface of CDs. This method is facile, rapid, low cost, and environment-friendly. A detection limit as low as 2.3×10(-8) M for Cu(2+) and 3.4×10(-10) M for L-Cys is obtained, which is promising for biological applications. © 2013 Elsevier B.V. All rights reserved.

  20. Spectral-fluorescent study of the interaction of the polymethine dye probe Cyan 2 with chondroitin-4-sulfate

    Science.gov (United States)

    Tatikolov, Alexander S.; Akimkin, Timofey M.; Panova, Ina G.; Yarmoluk, Sergiy M.

    2017-04-01

    The noncovalent interaction of the polymethine dye probe 3,3‧,9-trimethylthiacarbocyanine iodide (Cyan 2) with chondroitin-4-sulfate (C4S) in buffer solutions with different pH and in water in the absence of buffers has been studied by spectral-fluorescent methods. It has been shown that in all media studied, at relatively high concentrations, the dye is bound to C4S mainly as a monomer, which is accompanied by a steep rise of fluorescence (the intermediate formation of dye aggregates on the biopolymer is also observed). From the dependence of the fluorescence quantum yield on the concentration of C4S, the parameters of binding of the dye monomer to C4S were obtained: the effective binding constant K, the number of the monomeric C4S units n per one dye monomer bound to C4S, and the fluorescence quantum yield of the bound dye monomer Φfb. The dependence of Φfb (and K) on pH of the medium is not monotonic: it has a minimum in the region of neutral pH and a growth in the regions of acid and basic pH. This can be explained by changing the charge of a C4S macromolecule as a function of pH and related conformational alterations in the biopolymer, which can affect the rigidity of a dye molecule and the energy of its interaction with the biopolymer.

  1. Y2O3: Eu,Zn nanocrystals as a fluorescent probe for the detection of biotin

    International Nuclear Information System (INIS)

    Ganjkhanlou, Y.; Hosseinnia, A.; Kazemzad, M.; Khanlarkhani, A.; Moghaddam, A.B.

    2012-01-01

    We report on the application of nanocrystals (NCs) of the type Y 2 O 3 : Eu,Zn as a probe for the fluorescent detection of biotin in aqueous solution. The NCs were dispersed in water in the presence of various surface modifiers including mercaptoethanol (ME), monoethanolamine and ethylene glycol. Both the absorbance of surfactant and the stability of the suspensions were investigated in order to optimize the experimental conditions. ME is found to be the most suitable surfactant for stabilization of the suspended NCs. Their photoluminescence intensity is found to be quenched by biotin. The Stern-Volmer constant for the quenching process is 7.6 x 10 3 M -1 . This NC probe can be applied to the detection of biotin in the 1-60 μM concentration range with detection limit of 1.89 μM. The possible mechanisms of quenching also are discussed. (author)

  2. Application of lipid peroxidation and protein oxidation biomarkers for oxidative damage in mammalian cells. A comparison with two fluorescent probes.

    Science.gov (United States)

    Orhan, H; Gurer-Orhan, H; Vriese, E; Vermeulen, N P E; Meerman, J H N

    2006-09-01

    We recently developed two biomarker sets for oxidative damage: one for determination of lipid peroxidation (LPO) degradation products; acetaldehyde, propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, malondialdehyde and acetone, by a gas chromatography-electron capture detection method, and the other for protein oxidation products such as o,o'-dityrosine, by an isotope dilution high performance liquid chromatography-tandem mass spectrometry method. In the present study, we explored the possibility to utilize these biomarkers for determining the oxidative damage in liver mammalian cells in vitro. Two different treatments were chosen for inducing oxidative stress in Chinese Hamster ovary cells: menadione and copper plus hydrogen peroxide (Cu2+/H2O2). Cells were incubated with the model compounds in the presence or absence of vitamin E and C, and cytotoxicity was evaluated by a nuclear-dye method. Results were compared to two fluorescent probes, H2DCF-DA and C11 -BODIPY581/591, which have been used for determining the formation of free radicals in the cells. From ten LPO degradation products, eight were increased significantly following incubation with menadione in cell lysate or incubation media. Menadione-induced oxidative stress was also confirmed by oxidation of fluorescent probes. However, no increased formation of protein oxidation products was observed. Vitamin E and C did not diminish the formation of LPO degradation products that were increased by menadione. Although Cu2+/H2O2 did not induce oxidation of fluorescent probes, it induced formation of six out of ten LPO degradation products. Vitamin E and C did not diminish the formation of LPO degradation products; vitamin C even substantially increased the formation of acetaldehyde and propanal, which is in line with its reported prooxidant action under certain conditions. Vitamin C also caused two-fold increase in Cu2+/H2O2-induced o,o'-dityrosine formation when applied simultaneously. In

  3. Hydrophobic analogues of rhodamine B and rhodamine 101: potent fluorescent probes of mitochondria in living C. elegans

    Directory of Open Access Journals (Sweden)

    Laurie F. Mottram

    2012-12-01

    Full Text Available Mitochondria undergo dynamic fusion and fission events that affect the structure and function of these critical energy-producing cellular organelles. Defects in these dynamic processes have been implicated in a wide range of human diseases including ischemia, neurodegeneration, metabolic disease, and cancer. To provide new tools for imaging of mitochondria in vivo, we synthesized novel hydrophobic analogues of the red fluorescent dyes rhodamine B and rhodamine 101 that replace the carboxylate with a methyl group. Compared to the parent compounds, methyl analogues termed HRB and HR101 exhibit slightly red-shifted absorbance and emission spectra (5–9 nm, modest reductions in molar extinction coefficent and quantum yield, and enhanced partitioning into octanol compared with aqueous buffer of 10-fold or more. Comparison of living C. elegans (nematode roundworm animals treated with the classic fluorescent mitochondrial stains rhodamine 123, rhodamine 6G, and rhodamine B, as well as the structurally related fluorophores rhodamine 101, and basic violet 11, revealed that HRB and HR101 are the most potent mitochondrial probes, enabling imaging of mitochondrial motility, fusion, and fission in the germline and other tissues by confocal laser scanning microscopy after treatment for 2 h at concentrations as low as 100 picomolar. Because transgenes are poorly expressed in the germline of these animals, these small molecules represent superior tools for labeling dynamic mitochondria in this tissue compared with the expression of mitochondria-targeted fluorescent proteins. The high bioavailabilty of these novel fluorescent probes may facilitate the identification of agents and factors that affect diverse aspects of mitochondrial biology in vivo.

  4. A Thiazole Coumarin (TC) Turn-On Fluorescence Probe for AT-Base Pair Detection and Multipurpose Applications in Different Biological Systems

    Science.gov (United States)

    Narayanaswamy, Nagarjun; Kumar, Manoj; Das, Sadhan; Sharma, Rahul; Samanta, Pralok K.; Pati, Swapan K.; Dhar, Suman K.; Kundu, Tapas K.; Govindaraju, T.

    2014-09-01

    Sequence-specific recognition of DNA by small turn-on fluorescence probes is a promising tool for bioimaging, bioanalytical and biomedical applications. Here, the authors report a novel cell-permeable and red fluorescent hemicyanine-based thiazole coumarin (TC) probe for DNA recognition, nuclear staining and cell cycle analysis. TC exhibited strong fluorescence enhancement in the presence of DNA containing AT-base pairs, but did not fluoresce with GC sequences, single-stranded DNA, RNA and proteins. The fluorescence staining of HeLa S3 and HEK 293 cells by TC followed by DNase and RNase digestion studies depicted the selective staining of DNA in the nucleus over the cytoplasmic region. Fluorescence-activated cell sorting (FACS) analysis by flow cytometry demonstrated the potential application of TC in cell cycle analysis in HEK 293 cells. Metaphase chromosome and malaria parasite DNA imaging studies further confirmed the in vivo diagnostic and therapeutic applications of probe TC. Probe TC may find multiple applications in fluorescence spectroscopy, diagnostics, bioimaging and molecular and cell biology.

  5. Chlorophyll fluorescence in vivo as a probe for rapid measurement of tolerance to ultraviolet radiation

    International Nuclear Information System (INIS)

    Smillie, R.M.

    1983-01-01

    Chlorophyll fluorescence in vivo was progressively lost in pea leaves irradiated with either short or long-wave light. The changes were consistent with the development in the intact leaves of an inhibitory site on the photooxidizing side of photosystem II. In contrast, leaves of two species of Agave, plants regarded as more resistant to UV radiation, showed only minor changes in chlorophyll fluorescence. Agave americana was affected less than A. attenuata. The application of measurements of chlorophyll fluorescence in vivo to screening for tolerance to UV radiation is discussed. (author)

  6. Quinolino-triazole linked gold nanoparticles as sensitive 'turn-on' fluorescent Cd2+ probes

    International Nuclear Information System (INIS)

    Yao Yao; Sun Zhongyue; Zou Zhilong; Li Haibing

    2011-01-01

    Quinoline derivatives were brought into the surface of gold nanoparticles (Au NPs) through click chemistry. The fluorescence was quenched by Au NPs because of electron transfer between Au NPs and quinoline. However, upon addition of Cd 2+ to the quinoline-triazole Au NP solution, it exhibited an effective switch-on fluorescence response, owing to the coordination between quinoline and Cd 2+ which can efficiently block the electron transfer. What's more, the fluorescent sensor can effectively detect Cd 2+ in aqueous solution with a detection limit of 1.0 x 10 -5 M.

  7. Direct visualization of nucleolar G-quadruplexes in live cells by using a fluorescent light-up probe.

    Science.gov (United States)

    Zhang, Suge; Sun, Hongxia; Chen, Hongbo; Li, Qian; Guan, Aijiao; Wang, Lixia; Shi, Yunhua; Xu, Shujuan; Liu, Meirong; Tang, Yalin

    2018-05-01

    Direct detection of G-quadruplexes in human cells has become an important issue due to the vital role of G-quadruplex related to biological functions. Despite several probes have been developed for detection of the G-quadruplexes in cytoplasm or whole cells, the probe being used to monitor the nucleolar G-quadruplexes is still lacking. Formation of the nucleolar G-quadruplex structures was confirmed by using circular dichroism (CD) spectroscopy. The binding affinity and selectivity of Thioflavin T (ThT) towards various DNA/RNA motifs in solution and gel system were measured by using fluorescence spectroscopy and polyacrylamide gel electrophoresis (PAGE), respectively. G-quadruplex imaging in live cells was directly captured by using confocal laser scanning microscopy (CLSM). Formation of the rDNA and rRNA G-quadruplex structures is demonstrated in vitro. ThT is found to show much higher affinity and selectivity towards these G-quadruplex structures versus other nucleic acid motifs either in solution or in gel system. The nucleolar G-quadruplexes in living cells are visualized by using ThT as a fluorescent probe. G-quadruplex-ligand treatments in live cells lead to sharp decrease of ThT signal. The natural existence of the G-quadruplexes structure in the nucleoli of living cells is directly visualized by using ThT as an indicator. The research provides substantive evidence for formation of the rRNA G-quadruplex structures, and also offers an effective probe for direct visualization of the nucleolar G-quadruplexes in living cells. Copyright © 2018. Published by Elsevier B.V.

  8. Imaging and Detection of Carboxylesterase in Living Cells and Zebrafish Pretreated with Pesticides by a New Near-Infrared Fluorescence Off-On Probe.

    Science.gov (United States)

    Li, Dongyu; Li, Zhao; Chen, Weihua; Yang, Xingbin

    2017-05-24

    A new near-infrared fluorescence off-on probe was developed and applied to fluorescence imaging of carboxylesterase in living HepG-2 cells and zebrafish pretreated with pesticides (carbamate, organophosphorus, and pyrethroid). The probe was readily prepared by connecting (4-acetoxybenzyl)oxy as a quenching and recognizing moiety to a stable hemicyanine skeleton that can be formed via the decomposition of IR-780. The fluorescence off-on response of the probe to carboxylesterase is based on the enzyme-catalyzed spontaneous hydrolysis of the carboxylic ester bond, followed by a further fragmentation of the phenylmethyl unit and thereby the fluorophore release. Compared with the only existing near-infrared carboxylesterase probe, the proposed probe exhibits superior analytical performance, such as near-infrared fluorescence emission over 700 nm as well as high selectivity and sensitivity, with a detection limit of 4.5 × 10 -3 U/mL. More importantly, the probe is cell membrane permeable, and its applicability has been successfully demonstrated for monitoring carboxylesterase activity in living HepG-2 cells and zebrafish pretreated with pesticides, revealing that pesticides can effectively inhibit the activity of carboxylesterase. The superior properties of the probe make it of great potential use in indicating pesticide exposure.

  9. Ultrafast polarized fluorescence measurements on monomeric and self-associated melittin

    NARCIS (Netherlands)

    Pandit, A.; Larsen, O.F.A.; Stokkum, van I.H.M.; Grondelle, van R.; Kraayenhof, R.; Amerongen, van H.

    2003-01-01

    The anisotropic and magic-angle fluorescence decay of the single tryptophan (Trp) residue of melittin, a bee venom peptide, was investigated by time-resolved fluorescence anisotropy using a streak camera setup. The peptide was dissolved either in distilled water or in Hepes/NaOH buffer containing

  10. Probing membrane protein structure using water polarization transfer solid-state NMR.

    Science.gov (United States)

    Williams, Jonathan K; Hong, Mei

    2014-10-01

    Water plays an essential role in the structure and function of proteins, lipid membranes and other biological macromolecules. Solid-state NMR heteronuclear-detected (1)H polarization transfer from water to biomolecules is a versatile approach for studying water-protein, water-membrane, and water-carbohydrate interactions in biology. We review radiofrequency pulse sequences for measuring water polarization transfer to biomolecules, the mechanisms of polarization transfer, and the application of this method to various biological systems. Three polarization transfer mechanisms, chemical exchange, spin diffusion and NOE, manifest themselves at different temperatures, magic-angle-spinning frequencies, and pulse irradiations. Chemical exchange is ubiquitous in all systems examined so far, and spin diffusion plays the key role in polarization transfer within the macromolecule. Tightly bound water molecules with long residence times are rare in proteins at ambient temperature. The water polarization-transfer technique has been used to study the hydration of microcrystalline proteins, lipid membranes, and plant cell wall polysaccharides, and to derive atomic-resolution details of the kinetics and mechanism of ion conduction in channels and pumps. Using this approach, we have measured the water polarization transfer to the transmembrane domain of the influenza M2 protein to obtain information on the structure of this tetrameric proton channel. At short mixing times, the polarization transfer rates are site-specific and depend on the pH, labile protons, sidechain conformation, as well as the radial position of the residues in this four-helix bundle. Despite the multiple dependences, the initial transfer rates reflect the periodic nature of the residue positions from the water-filled pore, thus this technique provides a way of gleaning secondary structure information, helix tilt angle, and the oligomeric structure of membrane proteins. Copyright © 2014 Elsevier Inc. All

  11. A nucleic acid probe labeled with desmethyl thiazole orange: a new type of hybridization-sensitive fluorescent oligonucleotide for live-cell RNA imaging.

    Science.gov (United States)

    Okamoto, Akimitsu; Sugizaki, Kaori; Yuki, Mizue; Yanagisawa, Hiroyuki; Ikeda, Shuji; Sueoka, Takuma; Hayashi, Gosuke; Wang, Dan Ohtan

    2013-01-14

    A new fluorescent nucleotide with desmethyl thiazole orange dyes, D'(505), has been developed for expansion of the function of fluorescent probes for live-cell RNA imaging. The nucleoside unit of D'(505) for DNA autosynthesis was soluble in organic solvents, which made the preparation of nucleoside units and the reactions in the cycles of DNA synthesis more efficient. The dyes of D'(505)-containing oligodeoxynucleotide were protonated below pH 7 and the oligodeoxynucleotide exhibited hybridization-sensitive fluorescence emission through the control of excitonic interactions of the dyes of D'(505). The simplified procedure and effective hybridization-sensitive fluorescence emission produced multicolored hybridization-sensitive fluorescent probes, which were useful for live-cell RNA imaging. The acceptor-bleaching method gave us information on RNA in a specific cell among many living cells.

  12. A lysosome-targetable turn-on fluorescent probe for the detection of thiols in living cells based on a 1,8-naphthalimide derivative

    Science.gov (United States)

    Liang, Beibei; Wang, Baiyan; Ma, Qiujuan; Xie, Caixia; Li, Xian; Wang, Suiping

    2018-03-01

    Biological thiols, like cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), play crucial roles in biological systems and in lysosomal processes. Highly selective probes for detecting biological thiols in lysomes of living cells are rare. In this work, a lysosome-targetable turn-on fluorescent probe for the detection of thiols in living cells was designed and synthesized based on a 1,8-naphthalimide derivative. The probe has a 4-(2-aminoethyl)morpholine unit as a lysosome-targetable group and an acrylate group as the thiol recognition unit as well as a fluorescence quencher. In the absence of biothiols, the probe displayed weak fluorescence due to the photoinduced electron transfer (PET) process. Upon the addition of biothiols, the probe exhibited an enhanced fluorescence emission centered at 550 nm due to cleavage of the acrylate moiety. The probe had high selectivity toward biothiols. Moreover, the probe features fast response time, excitation in the visible region and ability of working in a wide pH range. The linear response range covers a concentration range of Cys from 1.5 × 10- 7 to 1.0 × 10- 5 mol·L- 1 and the detection limit is 6.9 × 10- 8 mol·L- 1 for Cys. The probe has been successfully applied to the confocal imaging of biothiols in lysosomes of A549 cells with low cell toxicity. Furthermore, the method was successfully applied to the determination of thiols in a complex multicomponent mixture such as human serum, which suggests our proposed method has great potential for diagnostic purposes. All of such good properties prove it can be used to monitor biothiols in lysosomes of living cells and to be a good fluorescent probe for the selective detection of thiols.

  13. Multi-instrument probing of the polar ionosphere under steady northward IMF

    Directory of Open Access Journals (Sweden)

    S. E. Pryse

    2000-01-01

    Full Text Available Observations are presented of the polar ionosphere under steady, northward IMF. The measurements, made by six complementary experimental techniques, including radio tomography, all-sky and meridian scanning photometer optical imaging, incoherent and coherent scatter radars and satellite particle detection, reveal plasma parameters consistent with ionospheric signatures of lobe reconnection. The optical green-line footprint of the reconnection site is seen to lie in the sunward plasma convection of the lobe cells. Downstream in the region of softer precipitation the reverse energy dispersion of the incoming ions can be identified. A steep latitudinal density gradient at the equatorward edge of the precipitation identifies the general location of an adiaroic boundary, separating the open field lines of polar lobe cells from the closed field of viscous-driven cells. Enhancements in plasma density to the south of the gradient are interpreted as ionisation being reconfigured as it is thrust against the boundary by the antisunward flow of the viscous cells near noon. Each of the instruments individually provides valuable information on certain aspects of the ionosphere, but the paper demonstrates that taken together the different experiments complement each other to give a consistent and comprehensive picture of the dayside polar ionosphere..Key words. Ionosphere (polar ionosphere · Magnetospheric physics (magnetosphere-ionosphere interactions; polar cap phenomena

  14. Multi-instrument probing of the polar ionosphere under steady northward IMF

    Directory of Open Access Journals (Sweden)

    S. E. Pryse

    Full Text Available Observations are presented of the polar ionosphere under steady, northward IMF. The measurements, made by six complementary experimental techniques, including radio tomography, all-sky and meridian scanning photometer optical imaging, incoherent and coherent scatter radars and satellite particle detection, reveal plasma parameters consistent with ionospheric signatures of lobe reconnection. The optical green-line footprint of the reconnection site is seen to lie in the sunward plasma convection of the lobe cells. Downstream in the region of softer precipitation the reverse energy dispersion of the incoming ions can be identified. A steep latitudinal density gradient at the equatorward edge of the precipitation identifies the general location of an adiaroic boundary, separating the open field lines of polar lobe cells from the closed field of viscous-driven cells. Enhancements in plasma density to the south of the gradient are interpreted as ionisation being reconfigured as it is thrust against the boundary by the antisunward flow of the viscous cells near noon. Each of the instruments individually provides valuable information on certain aspects of the ionosphere, but the paper demonstrates that taken together the different experiments complement each other to give a consistent and comprehensive picture of the dayside polar ionosphere..

    Key words. Ionosphere (polar ionosphere · Magnetospheric physics (magnetosphere-ionosphere interactions; polar cap phenomena

  15. Selective fluorescent probes based on C dbnd N isomerization and intramolecular charge transfer (ICT) for zinc ions in aqueous solution

    Science.gov (United States)

    Li, Lei; Liu, Feng; Li, Hong-Wei

    2011-09-01

    As the second most abundant transition-metal ion in the human body, Zn 2+ plays crucial roles in many important biological processes; while in the environment, an excessive concentration of Zn 2+ may reduce the soil microbial activity resulting in phytotoxic effects. Therefore, developing effective and sensitive detection method for Zn 2+ has become crucially important and necessary both in life and environment science. Two new fluorescence probes, 2-((2-hydroxynaphthalen-1-yl)methyleneamino)-3-(1H-imidazol-5-yl) propanoic acid ( 2) and 2-hydroxy-2-((2-hydroxynaphthalen-1-yl) methyleneamino) acetic acid ( 3), were easily prepared by a one step reaction between 2-hydroxy-1-naphthaldehyde with histidine and serine, respectively, in ethanol. The optical properties of them were investigated by fluorescence spectra, which displayed specific and sensitive recognition to Zn 2+ and especially avoided the interference of Cd 2+ when they were tested against a range of physiological and environmentally relevant metal ions in aqueous solution. The responsive mechanism of the two probes to Zn 2+ were involved both the C dbnd N isomerization and ICT, which were clarified by NBO charge analysis and the HOMO-LUMO energy gap calculation by using B3LYP/6-31G density functional theory.

  16. A light-up fluorescent probe for citrate detection based on bispyridinum amides with aggregation-induced emission feature.

    Science.gov (United States)

    Liu, Chenchen; Hang, Yandi; Jiang, Tao; Yang, Ji; Zhang, Xiao; Hua, Jianli

    2018-02-01

    Citrate is an important intermediate in the citric acid cycle, a vital metabolic pathway for animals, plants and bacteria. It is of great significance to detect its levels in human beings because several diseases may cause the abnormal of citrate. In this paper, a new turn-on fluorescent sensor (TPE-Py) using the classic tetraphenylethylene (TPE) as the aggregation-induced emission (AIE) fluorophore and bipyridinium-based amides as the recognition receptor has been synthesized for the detection of citrate. The probe exhibits good selectivity and sensitivity to citrate with a relatively low detection limit (1.0 × 10 -7 M). The enhancement of the fluorescence is relevant with the AIE property based on the complexation of TPE-Py with citrate caused by the hydrogen bonding and electrostatic interactions between the bipyridinium diamides and citrate, which has been proved by 1 H NMR and mass spectra titration, scanning electronic microscope and dynamic light scattering analyses. More importantly, the quantification of citrate in artificial urine may develop TPE-Py fluorometric probe for the citrate detection in real biosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Determination of lapachol in the presence of other naphthoquinones using 3MPA-CdTe quantum dots fluorescent probe

    Science.gov (United States)

    Aucélio, Ricardo Q.; Peréz-Cordovés, Ana I.; Xavier Lima, Juliano L.; Ferreira, Aurélio Baird B.; Esteva Guas, Ana M.; da Silva, Andrea R.

    3MPA-CdTe QDs in aqueous dispersion was used as a fluorescent probe for the determination of lapachol, a natural naphthoquinone found in plants of the Bignoniaceae family genus Tabebuia. Working QDs dispersions (4.5 × 10-8 mol L-1 of QDs) was prepared in aqueous media containing Tris-HCl buffer pH 7.4 and methanol (10% in volume). The excitation was made at 380 nm with signal measurement at 540 nm. To establish a relationship between fluorescence (corrected to inner filter effect) and concentration of lapachol, a Stern-Volmer model was used. The linear range obtained was from 1.0 × 10-5 to 1.0 × 10-4 mol L-1. The limit of detection (xb - 3 sb) was 8.0 × 10-6 mol L-1. The 3MPA-CdTe QDs probe was tested in the determination of lapachol in urine, previously cleansed in an acrylic polymer. The average recovery was satisfactory.

  18. Circularly Polarized X Rays: Another Probe of Ultrafast Molecular Decay Dynamics

    International Nuclear Information System (INIS)

    Travnikova, Oksana; Lindblad, Andreas; Nicolas, Christophe; Soederstroem, Johan; Kimberg, Victor; Miron, Catalin; Liu Jicai; Gel'mukhanov, Faris

    2010-01-01

    Dissociative nuclear motion in core-excited molecular states leads to a splitting of the fragment Auger lines: the Auger-Doppler effect. We present here for the first time experimental evidence for an Auger-Doppler effect following F1s→a 1g * inner-shell excitation by circularly polarized x rays in SF 6 . In spite of a uniform distribution of the dissociating S-F bonds near the polarization plane of the light, the intersection between the subpopulation of molecules selected by the core excitation with the cone of dissociation induces a strong anisotropy in the distribution of the S-F bonds that contributes to the scattering profile measured in the polarization plane.

  19. Amino acid detection using fluoroquinolone–Cu{sup 2+} complex as a switch-on fluorescent probe by competitive complexation without derivatization

    Energy Technology Data Exchange (ETDEWEB)

    Farokhcheh, Alireza; Alizadeh, Naader, E-mail: alizaden@modares.ac.ir

    2014-01-15

    In this work, we describe the use of fluoroquinolone–Cu{sup 2+} complex as a competitive switch-on fluorescence probe for amino acid determination without derivatization. The fluorescence intensity of this probe, which has been reduced due to effective quenching by Cu{sup 2+} ion, increases drastically by an addition of amino acid (glycine, phenylalanine, sarcosine, aspargine, alanine, proline, arginine, aspartic acid, glutamic acid, lysine, leucine and isoleucine). The overall stability constants of Cu{sup 2+} ion complexes with amino acids were determined by fluorometric titration of fluoroquinolone-Cu{sup 2+} complex with the amino acid solution. Furthermore, the probe shows high calibration sensitivity toward aspartic acid. The fluorescence signal depends linearly on the amino acid concentration within the range of concentration from 1.2×10{sup −7} to 1.1×10{sup −5} mol L{sup −1} for aspartic acid. The detection limit was found 2.7×10{sup −8} mol L{sup −1} with the relative standard deviation (RSD%) about 2.1% (five replicate). -- Highlights: • Amino acids are detected by using fluoroquinolone–Cu{sup 2+} complex as fluorescent probe. • Amino acids were detected based on a competitive complexation reaction. • Probe has been able to recognize amino acids through switch-on fluorescence behavior. • Ultra-trace level of aspartic and glutamic acid is determined without derivatization.

  20. A Conjugate of Pentamethine Cyanine and 18F as a Positron Emission Tomography/Near-Infrared Fluorescence Probe for Multimodality Tumor Imaging

    Directory of Open Access Journals (Sweden)

    Fei-Fei An

    2017-06-01

    Full Text Available The novel synthesis of a dual-modality, pentamethine cyanine (Cy5 fluorescent, 18F positron emission tomography (PET imaging probe is reported. The probe shows a large extinction coefficient and large quantum yield in the biologically transparent, near-infrared window (650–900 nm for in vivo fluorescent imaging. This fluorophore bears the isotope, 18F, giving a 18F-PET/near-infrared fluorescent (NIRF, bi-modal imaging probe, that combines the long-term stability of NIRF and the unlimited penetration depth of PET imaging. The bi-modal probe is labeled with 18F in a quick, one-step reaction, which is important in working with the rapid decay of 18F. The bi-modal probe bears a free carboxyl group, highlighting a PET/NIRF synthon that can be conjugated onto many advanced biomolecules for biomarker-specific in vivo dual-modal PET/NIR tumor imaging, confocal histology, and utility in multi-fluorophore, fluorescence-guided surgery. Its potential in vivo biocompatibility is explored in a quick proof-of-principal in vivo study. The dye is delivered to A549 xenograft flank-tumors to generate PET and NIRF signals at the tumor site. The tumor distribution is confirmed in ex vivo gamma counting and imaging. Pentamethine cyanine (Cy5 has the ability to preferentially accumulate in tumor xenografts. We substitute the PET/NIRF probe for Cy5, and explore this phenomenon.

  1. A Conjugate of Pentamethine Cyanine and18F as a Positron Emission Tomography/Near-Infrared Fluorescence Probe for Multimodality Tumor Imaging.

    Science.gov (United States)

    An, Fei-Fei; Kommidi, Harikrishna; Chen, Nandi; Ting, Richard

    2017-06-07

    The novel synthesis of a dual-modality, pentamethine cyanine (Cy5) fluorescent, 18 F positron emission tomography (PET) imaging probe is reported. The probe shows a large extinction coefficient and large quantum yield in the biologically transparent, near-infrared window (650-900 nm) for in vivo fluorescent imaging. This fluorophore bears the isotope, 18 F, giving a 18 F-PET/near-infrared fluorescent (NIRF), bi-modal imaging probe, that combines the long-term stability of NIRF and the unlimited penetration depth of PET imaging. The bi-modal probe is labeled with 18 F in a quick, one-step reaction, which is important in working with the rapid decay of 18 F. The bi-modal probe bears a free carboxyl group, highlighting a PET/NIRF synthon that can be conjugated onto many advanced biomolecules for biomarker-specific in vivo dual-modal PET/NIR tumor imaging, confocal histology, and utility in multi-fluorophore, fluorescence-guided surgery. Its potential in vivo biocompatibility is explored in a quick proof-of-principal in vivo study. The dye is delivered to A549 xenograft flank-tumors to generate PET and NIRF signals at the tumor site. The tumor distribution is confirmed in ex vivo gamma counting and imaging. Pentamethine cyanine (Cy5) has the ability to preferentially accumulate in tumor xenografts. We substitute the PET/NIRF probe for Cy5, and explore this phenomenon.

  2. Comparing in vivo pump–probe and multiphoton fluorescence microscopy of melanoma and pigmented lesions

    Science.gov (United States)

    Wilson, Jesse W.; Degan, Simone; Gainey, Christina S.; Mitropoulos, Tanya; Simpson, Mary Jane; Zhang, Jennifer Y.; Warren, Warren S.

    2014-01-01

    Abstract. We demonstrate a multimodal approach that combines a pump–probe with confocal reflectance and multiphoton autofluorescence microscopy. Pump–probe microscopy has been proven to be of great value in analyzing thin tissue sections of pigmented lesions, as it produces molecular contrast which is inaccessible by other means. However, the higher optical intensity required to overcome scattering in thick tissue leads to higher-order nonlinearities in the optical response of melanin (e.g., two-photon pump and one-photon probe) that present additional challenges for interpreting the data. We show that analysis of pigment composition in vivo must carefully account for signal terms that are nonlinear with respect to the pump and probe intensities. We find that pump–probe imaging gives useful contrast for pigmented structures over a large range of spatial scales (100  μm to 1 cm), making it a potentially useful tool for tracking the progression of pigmented lesions without the need to introduce exogenous contrast agents. PMID:25415567

  3. Enhanced fluorescence imaging of live cells by effective cytosolic delivery of probes.

    Directory of Open Access Journals (Sweden)

    Marzia Massignani

    Full Text Available BACKGROUND: Microscopic techniques enable real-space imaging of complex biological events and processes. They have become an essential tool to confirm and complement hypotheses made by biomedical scientists and also allow the re-examination of existing models, hence influencing future investigations. Particularly imaging live cells is crucial for an improved understanding of dynamic biological processes, however hitherto live cell imaging has been limited by the necessity to introduce probes within a cell without altering its physiological and structural integrity. We demonstrate herein that this hurdle can be overcome by effective cytosolic delivery. PRINCIPAL FINDINGS: We show the delivery within several types of mammalian cells using nanometre-sized biomimetic polymer vesicles (a.k.a. polymersomes that offer both highly efficient cellular uptake and endolysomal escape capability without any effect on the cellular metabolic activity. Such biocompatible polymersomes can encapsulate various types of probes including cell membrane probes and nucleic acid probes as well as labelled nucleic acids, antibodies and quantum dots. SIGNIFICANCE: We show the delivery of sufficient quantities of probes to the cytosol, allowing sustained functional imaging of live cells over time periods of days to weeks. Finally the combination of such effective staining with three-dimensional imaging by confocal laser scanning microscopy allows cell imaging in complex three-dimensional environments under both mono-culture and co-culture conditions. Thus cell migration and proliferation can be studied in models that are much closer to the in vivo situation.

  4. Quantum dots (QDs) based fluorescence probe for the sensitive determination of kaempferol

    Science.gov (United States)

    Tan, Xuanping; Liu, Shaopu; Shen, Yizhong; He, Youqiu; Yang, Jidong

    2014-12-01

    In this work, using the quenching of fluorescence of thioglycollic acid (TGA)-capped CdTe quantum dots (QDs), a novel method for the determination of kaempferol (KAE) has been developed. Under optimum conditions, a linear calibration plot of the quenched fluorescence intensity at 552 nm against the concentration of KAE was observed in the range of 4-44 μg mL-1 with a detection limit (3σ/K) of 0.79 μg mL-1. In addition, the detailed reaction mechanism has also been proposed on the basis of electron transfer supported by ultraviolet-visible (UV-vis) absorption and fluorescence (FL) spectroscopy. The method has been applied for the determination of KAE in pharmaceutical preparations with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.

  5. Thiophene-derivatized Fluorescent Benzamides as Possible Probes for Histone Deacetylases

    International Nuclear Information System (INIS)

    Seo, Young Jun

    2013-01-01

    We have synthesized a series of novel fluorescent benzamides inhibitors possessing intrinsic fluorescence properties. Most of these benzamide fluorophores exhibit high quantum yields, making them suitable for use in imaging studies, with colors ranging from blue to green; a couple of them were also water-soluble. Notably, TB1 and TB2 display a high quantum yield and TB1 exhibits high binding affinity to HDAC enzymes. We believe that these new fluorescent benzamide inhibitors might be useful diagnostic tools for in vitro studies of HDACs. Histone deacetylases (HDACs) are crucial gene regulating enzymes that control the expression of histones-epigenetic targets in research related to developing new therapies for cancer, central nervous system disorders, and heart disease. The deacetylation of histones is a vital repression process in transcriptional gene expression; it also affects apoptosis, cell-cycle arrest, and angiogenesis

  6. Thiophene-derivatized Fluorescent Benzamides as Possible Probes for Histone Deacetylases

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Young Jun [Chonbuk National Univ., Jeonju (Korea, Republic of)

    2013-08-15

    We have synthesized a series of novel fluorescent benzamides inhibitors possessing intrinsic fluorescence properties. Most of these benzamide fluorophores exhibit high quantum yields, making them suitable for use in imaging studies, with colors ranging from blue to green; a couple of them were also water-soluble. Notably, TB1 and TB2 display a high quantum yield and TB1 exhibits high binding affinity to HDAC enzymes. We believe that these new fluorescent benzamide inhibitors might be useful diagnostic tools for in vitro studies of HDACs. Histone deacetylases (HDACs) are crucial gene regulating enzymes that control the expression of histones-epigenetic targets in research related to developing new therapies for cancer, central nervous system disorders, and heart disease. The deacetylation of histones is a vital repression process in transcriptional gene expression; it also affects apoptosis, cell-cycle arrest, and angiogenesis.

  7. A novel pH-sensitive polymeric fluorescent probe: Synthesis, characterization and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Chen Dongyun; Xu Qingfeng; Xia Xuewei; Ge Jianfeng [Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu, 215123 (China); Lu Jianmei, E-mail: lujm@suda.edu.cn [Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu, 215123 (China); Li Najun, E-mail: linajun@sina.com [Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu, 215123 (China)

    2010-04-15

    A novel initiator containing proflavine derivative moiety, 3,6-dibromo-isobutyramide acridine (DIA), was synthesized and initiated the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). A water-soluble monomer, N,N-dimethylacrylamide (DMAA) was also initiated by DIA for comparison. The obtained fluorescent polymers, PMMA-DIA and PDMAA-DIA, were characterized by {sup 1}H NMR, GPC and TGA. The emission spectra of the fluorescent polymers exhibit obvious changes in color and fluorescence intensity along with pH varied in range of 3.0-9.0. In addition, the obtained polymers present good film-forming capacity and the films also have a high quantum yield and pH response. Both oil-soluble PMMA-DIA and water-soluble PDMAA-DIA have steady optical and chemical properties by containing proflavine moiety in the main chain.

  8. Fluorescent carbon nanoparticles derived from natural materials of mango fruit for bio-imaging probes

    Science.gov (United States)

    Jeong, Chan Jin; Roy, Arup Kumer; Kim, Sung Han; Lee, Jung-Eun; Jeong, Ji Hoon; Insik; Park, Sung Young

    2014-11-01

    Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials.Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04805a

  9. A non perturbative optical probe for laser induced fluorescence diagnostics in magnetized plasma

    International Nuclear Information System (INIS)

    Anderegg, F.; Paris, P.J.; Skiff, F.; Good, T.N.; Tran, M.Q.

    1988-01-01

    An 'optical carriage' has been developed to improve plasma access for LIF diganostics. Laser light inducing the fluorescence is transported through an optical fiber to the carriage. A telescope fixed on the carriage collects the plasma fluorescence light and sends it through a fiber bundle to an external PMT. The whole carriage is mounted on rails and can be scanned along and acrosss magnetic field. Wave interferograms and slow rotation of a plasma measured via LIF and optical tagging demonstrate the flexibility of the 'optical carriage'. (author) 4 figs., 8 refs

  10. A Conjugated Aptamer-Gold Nanoparticle Fluorescent Probe for Highly Sensitive Detection of rHuEPO-α

    Directory of Open Access Journals (Sweden)

    Zhaoyang Zhang

    2011-11-01

    Full Text Available We present here a novel conjugated aptamer-gold nanoparticle (Apt-AuNPs fluorescent probe and its application for specific detection of recombinant human erythropoietin-α (rHuEPO-α. In this nanobiosensor, 12 nm AuNPs function as both a nano-scaffold and a nano-quencher (fluorescent energy acceptor, on the surface of which the complementary sequences are linked (as cODN-AuNPs and pre-hybridized with carboxymethylfluorescein (FAM-labeled anti-rHuEPO-α aptamers. Upon target protein binding, the aptamers can be released from the AuNP surface and the fluorescence signal is restored. Key variables such as the length of linker, the hybridization site and length have been designed and optimized. Full performance evaluation including sensitivity, linear range and interference substances are also described. This nanobiosensor provides a promising approach for a simple and direct quantification of rHuEPO-α concentrations as low as 0.92 nM within a few hours.

  11. Characterization of the vitreous body of the human eye using a cyanine dye as a spectral and fluorescent probe

    Science.gov (United States)

    Panova, Ina G.; Tatikolov, Alexander S.

    2009-02-01

    We used one of cyanine dyes as a spectral and fluorescent probe in the study of the composition of the extracellular matrix of the human eye (its vitreous body). Owing to the unique ability of the dye to bind to collagens and human serum albumin, we revealed the simultaneous presence of both types of biomacromolecules in the vitreous body. The formation of the dye complex with human serum albumin leads to appearance of a long-wavelength absorption band (~612 nm) and a steep rise of fluorescence, whereas in the presence of collagens the dye forms J-aggregates with a longer-wavelength absorption band (640-660 nm) and moderate fluorescence. In this work we studied the composition of the human fetus vitreous body and its dynamics from 9 to 31 gestation weeks. On the basis of the data obtained by this method, we may assume that albumin, being a carrier protein, probably provides the vitreous body and surrounding tissues with necessary growth factors, hormones, lipids, vitamins, and some other biomolecules. The data show that the dye is promising not only for study of albumin functions in eye development, but also for characterization of some eye diseases and for analysis of other extracellular media.

  12. Fluorescence Based Turn-on Probe for the Determination of Caffeine Using Europium-Tetracycline as Energy Transfer Complex.

    Science.gov (United States)

    Nanjundaiah, Shwetha; Krishna, Honnur; Bhatt, Praveena

    2016-05-01

    The study describes a simple and sensitive fluorometric sensor based on the enhancement of fluorescence intensity of Europium ion (Eu(3+)) - tetracycline (TC) charge transfer complex on addition of caffeine. The Eu(3+)-TC ternary complex has a characteristic emission peak at 615 nm (λex = 375 nm), the intensity of which increases with increase in concentration of caffeine. The caffeine sensor assay was found to be linear in the range of 0.0515 mM to 51.5 mM. The limit of detection and quantification were found to be 0.0515 mM and 0.382 mM, respectively. A caffeine recovery of 90 to 110 % in biological samples (serum and urine) indicated minimal interference by commonly present excipients in the samples. Rosenthal plots to calculate the binding capacity of caffeine with the Eu(3+)- TC complex revealed an association constant (K) of 238 x 10(3) L/mol and binding number (N) of 1.9. Bland-Altman plot comparing the developed assay and HPLC showed good agreement between values obtained by both the methods. The proposed fluorescent chemical sensor is a rapid and convenient method to determine caffeine with excellent recovery and low detection limit. The probable reaction mechanism for the formation of the turn on fluorescent probe enhancer is discussed.

  13. Design and synthesis of new fluorescent probe for rapid and highly sensitive detection of proteins via electrophoretic gel stain.

    Science.gov (United States)

    Suzuki, Yoshio; Takagi, Nobuyuki; Chimuro, Tomoyuki; Shinohara, Atsushi; Sakaguchi, Nao; Hiratsuka, Atsunori; Yokoyama, Kenji

    2011-06-01

    A new fluorescent molecular probe, 2,2'-(1E,1'E)-2,2'-(4-(dicyanomethylene)-4H-pyrane-2,6-diyl)bis(ethene-2,1-diyl)bis(sodium benzenesulfonate) salt (1), possessing the cyanopyranyl moieties and two benzene sulfonic acid groups was designed and synthesized to detect proteins in solution and for high-throughput SDS-PAGE. Compound 1 exhibited no fluorescence in the absence of proteins; however, it exhibited strong fluorescence on the addition of bovine serum albumin as a result of intramolecular charge transfer. Compared with the conventional protocols for in-gel protein staining, such as SYPRO Ruby and silver staining, 1 achieves higher sensitivity, even though it offers a simplified, higher throughput protocol. In fact, the total time required for protein staining was 60-90 min under optimum conditions much shorter than that required by the less-sensitive silver staining or SYPRO Ruby staining protocols. Moreover, 1 was successfully applied to protein identification by mass spectrometry via in-gel tryptic digestion, Western blotting, and native PAGE together with protein staining by 1, which is a modified protocol of blue native PAGE (BN-PAGE). Thus, 1 may facilitate high-sensitivity protein detection, and it may be widely applicable as a convenient tool in various scientific and medical fields. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A Bright Future for Precision Medicine: Advances in Fluorescent Chemical Probe Design and Their Clinical Application.

    Science.gov (United States)

    Garland, Megan; Yim, Joshua J; Bogyo, Matthew

    2016-01-21

    The Precision Medicine Initiative aims to use advances in basic and clinical research to develop therapeutics that selectively target and kill cancer cells. Under the same doctrine of precision medicine, there is an equally important need to visualize these diseased cells to enable diagnosis, facilitate surgical resection, and monitor therapeutic response. Therefore, there is a great opportunity for chemists to develop chemically tractable probes that can image cancer in vivo. This review focuses on recent advances in the development of optical probes, as well as their current and future applications in the clinical management of cancer. The progress in probe development described here suggests that optical imaging is an important and rapidly developing field of study that encourages continued collaboration among chemists, biologists, and clinicians to further refine these tools for interventional surgical imaging, as well as for diagnostic and therapeutic applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. New probe for fluorescence detection of Azinphous ethyl, Malathion and Heptachlor pesticides

    International Nuclear Information System (INIS)

    Azab, Hassn A.; Orabi, Adel S.; Abbas, Abbas M.

    2015-01-01

    Luminescence quenching of long lived Eu(III)–Bathophenanthroline (Batho) probe of 1:2 stoichiometric ratio has been studied in acetonitrile in the presence of the pesticides Azinphous ethyl (P1), Malathion (P2) and Heptachlor (P3). The luminescence intensity of Eu(III)–(Batho) 2 probe decreases as the concentration of the pesticide increases. Direct methods for the determination of the pesticides under investigation have been developed using the luminescence quenching of Eu(III)–(Batho) 2 probe in solution. The detection limits were 0.68, 0.92 and 0.35 µM for P1, P2 and P3, respectively. Stern–Volmer studies at different temperatures indicate that collisional quenching dominates for Azinphous ethyl, Malathion and Heptachlor. The binding constants (K) and thermodynamic parameters (ΔS°, ∆H° and ∆G°) of the interaction of pesticides with the complex were evaluated

  16. Photoelectron angular distributions from polar molecules probed by intense femtosecond lasers

    DEFF Research Database (Denmark)

    Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2010-01-01

    -active-electron and frozen-nuclei approximations. Our analysis shows that for the HF and LiF molecules, anisotropies in the molecular potential and the probed orbital lead to enhanced ionization during laser half cycles with the field pointing antiparallel to the permanent dipole of the dipole term in a multipolar expansion...

  17. Optical polarization properties of a nanowire quantum dot probed along perpendicular orientations

    NARCIS (Netherlands)

    Bugarini, G.; Reimer, M.E.; Zwiller, V.

    2012-01-01

    We report on the optical properties of single quantum dots in nanowires probed along orthogonal directions. We address the same quantum dot from either the nanowire side or along the nanowire axis via reflection on a micro-prism. The collected photoluminescence intensity from nanowires lying on a

  18. Probing spin-polarized tunneling at high bias and temperature with a magnetic tunnel transistor

    NARCIS (Netherlands)

    Park, B.G.; Banerjee, T.; Min, B.C.; Sanderink, Johannes G.M.; Lodder, J.C.; Jansen, R.

    2005-01-01

    The magnetic tunnel transistor (MTT) is a three terminal hybrid device that consists of a tunnel emitter, a ferromagnetic (FM) base, and a semiconductor collector. In the MTT with a FM emitter and a single FM base, spin-polarized hot electrons are injected into the base by tunneling. After

  19. Probing space–time structure of new physics with polarized beams ...

    Indian Academy of Sciences (India)

    Abstract. At the international linear collider large beam polarization of both the elec- tron and positron beams will enhance the signature of physics due to interactions that are beyond the standard model. Here we review our recently obtained results on a general model-independent method of determining for an arbitary ...

  20. Probing the endocytic pathways of the filamentous bacteriophage in live cells using ratiometric pH fluorescent indicator.

    Science.gov (United States)

    Tian, Ye; Wu, Man; Liu, Xiangxiang; Liu, Zhi; Zhou, Quan; Niu, Zhongwei; Huang, Yong

    2015-02-18

    Viral nanoparticles have attracted extensive research interests in diverse applications of diagnosis and therapy. In particular, filamentous M13 bacteriophages have shown great potential in biomedical applications. However, its pathways entering into cells still remain unclear, and this greatly hinders its further use as a drug or gene carrier. Here, a ratiometric M13 pH probe is designed by conjugating two fluorescent dyes onto the surface of M13. Since the intensity ratio is not influenced by probe concentration, ion strength, temperature, photobleaching, and optical path length, this ratiometric probe can be used to investigate the intracellular pH map of M13. More importantly, the internalization mechanism of M13 can be elucidated. It is found that this filamentous phage shows great cell-type dependence in interaction with cells and internalization mechanism. The phage tends to be bounded on the cell membrane of only epithelial cells, not endothelial cells. Furthermore, the M13 phage enters into cells through endocytosis with specific mechanism: clathrin-mediated endocytosis and macropinocytosis for HeLa; vesicular transport, clathrin-mediated endocytosis, and macropinocytosis for MCF-7; caveolae-mediated endocytosis for human dermal microvascular endothelial cell (HDMEC). This work provides key notes for cancer diagnosis and therapy based on filamentous bacteriophage, especially for design of pH-sensitive drug delivery systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Methionine-Capped Gold Nanoclusters as a Fluorescence-Enhanced Probe for Cadmium(II Sensing

    Directory of Open Access Journals (Sweden)

    Yan Peng

    2018-02-01

    Full Text Available Gold nanoclusters (Au NCs have been considered as novel heavy metal ions sensors due to their ultrafine size, photo-stability and excellent fluorescent properties. In this study, a green and facile method was developed for the preparation of fluorescent water-soluble gold nanoclusters with methionine as a stabilizer. The nanoclusters emit orange fluorescence with excitation/emission peaks at 420/565 nm and a quantum yield of about 1.46%. The fluorescence of the Au NCs is selectively and sensitively enhanced by addition of Cd(II ions attributed to the Cd(II ion-induced aggregation of nanoclusters. This finding was further used to design a fluorometric method for the determination of Cd(II ions, which had a linear response in the concentration range from 50 nM to 35 μM and a detection limit of 12.25 nM. The practicality of the nanoprobe was validated in various environmental water samples and milk powder samples, with a fairly satisfactory recovery percent.

  2. A subnanomolar fluorescent probe for protein kinase CK2 interaction studies

    DEFF Research Database (Denmark)

    Enkvist, Erki; Viht, Kaido; Bischoff, Nils

    2012-01-01

    assay that used thin layer chromatography for the measurement of the rate of phosphorylation of fluorescently labelled peptide 5-TAMRA-RADDSDDDDD. The most potent inhibitor, ARC-1502 (K(i) = 0.5 nM), revealed high selectivity for CK2α in a panel of 140 protein kinases. Labelling of ARC-1502 with Promo...

  3. A novel fluorescent turn-on probe for bisulfite based on NBD ...

    Indian Academy of Sciences (India)

    tain concentrations has been associated with allergic reaction and food intolerance symptoms, such as diffi- culty in breathing, wheezing, hives, and gastrointesti- nal distress.30–34 Therefore, development of a sensitive and selective fluorescent sensor for the determination of bisulfite is of great importance for food safety ...

  4. ABC transporters affect the detection of intracellular oxidants by fluorescent probes

    Czech Academy of Sciences Publication Activity Database

    Procházková, J.; Kubala, Lukáš; Kotasová, H.; Gudernová, I.; Šrámková, Z.; Pekarová, Michaela; Sarkadi, B.; Pachernik, J.

    2011-01-01

    Roč. 45, č. 7 (2011), s. 779-787 ISSN 1071-5762 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Institutional support: RVO:68081707 Keywords : Fluorescence * redox status * mitochondria Subject RIV: BO - Biophysics Impact factor: 2.878, year: 2011

  5. Mapping of wave packets in direct fragmentation via pump-probe frequency integrated fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Engel, Volker; Henriksen, Niels Engholm

    2000-01-01

    We consider femtosecond excitation of a molecule to a dissociative electronic state. The quantum dynamics is recorded via delayed excitation to a higher electronic state and measurement of the total fluorescence from this state detected as a function of delay time. It is shown that the signal can...

  6. A novel fluorescent turn-on probe for bisulfite based on NBD ...

    Indian Academy of Sciences (India)

    scent samples due to its simplicity, sensitivity, fast ... reaction and food intolerance symptoms, such as diffi- culty in breathing, wheezing, hives, and gastrointesti- nal distress.30–34 Therefore, development of a sensitive and selective fluorescent sensor for the determination of bisulfite is of great importance for food safety and.

  7. Fluorescence spectral correlation spectroscopy (FSCS) for probes with highly overlapping emission spectra

    Czech Academy of Sciences Publication Activity Database

    Benda, A.; Kapusta, Peter; Hof, Martin; Gaus, K.

    2014-01-01

    Roč. 22, č. 3 (2014), s. 2973-2988 ISSN 1094-4087 R&D Projects: GA AV ČR KJB400400904; GA ČR GBP208/12/G016 Institutional support: RVO:61388955 Keywords : spectroscopy * fluorescence and luminiscence * confocal microscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.488, year: 2014

  8. Beveled fiber-optic probe couples a ball lens for improving depth-resolved fluorescence measurements of layered tissue: Monte Carlo simulations

    International Nuclear Information System (INIS)

    Jaillon, Franck; Zheng Wei; Huang Zhiwei

    2008-01-01

    In this study, we evaluate the feasibility of designing a beveled fiber-optic probe coupled with a ball lens for improving depth-resolved fluorescence measurements of epithelial tissue using Monte Carlo (MC) simulations. The results show that by using the probe configuration with a beveled tip collection fiber and a flat tip excitation fiber associated with a ball lens, discrimination of fluorescence signals generated in different tissue depths is achievable. In comparison with a flat-tip collection fiber, the use of a large bevel angled collection fiber enables a better differentiation between the shallow and deep tissue layers by changing the excitation-collection fiber separations. This work suggests that the beveled fiber-optic probe coupled with a ball lens has the potential to facilitate depth-resolved fluorescence measurements of epithelial tissues

  9. Beveled fiber-optic probe couples a ball lens for improving depth-resolved fluorescence measurements of layered tissue: Monte Carlo simulations.

    Science.gov (United States)

    Jaillon, Franck; Zheng, Wei; Huang, Zhiwei

    2008-02-21

    In this study, we evaluate the feasibility of designing a beveled fiber-optic probe coupled with a ball lens for improving depth-resolved fluorescence measurements of epithelial tissue using Monte Carlo (MC) simulations. The results show that by using the probe configuration with a beveled tip collection fiber and a flat tip excitation fiber associated with a ball lens, discrimination of fluorescence signals generated in different tissue depths is achievable. In comparison with a flat-tip collection fiber, the use of a large bevel angled collection fiber enables a better differentiation between the shallow and deep tissue layers by changing the excitation-collection fiber separations. This work suggests that the beveled fiber-optic probe coupled with a ball lens has the potential to facilitate depth-resolved fluorescence measurements of epithelial tissues.

  10. A Non-perturbing Probe of Coiled Coil Formation Based on Electron Transfer Mediated Fluorescence Quenching.

    Science.gov (United States)

    Watson, Matthew D; Peran, Ivan; Raleigh, Daniel P

    2016-07-05

    Coiled coils are abundant in nature, occurring in ∼3% of proteins across sequenced genomes, and are found in proteins ranging from transcription factors to structural proteins. The motif continues to be an important model system for understanding protein-protein interactions and is finding increased use in bioinspired materials and synthetic biology. Knowledge of the thermodynamics of self-assembly, particularly the dissociation constant KD, is essential for the application of designed coiled coils and for understanding the in vivo specificity of natural coiled coils. Standard methods for measuring KD typically rely on concentration dependent circular dichroism (CD). Fluorescence methods are an attractive alternative; however Trp is rarely found in an interior position of a coiled coil, and appending unnatural fluorophores can perturb the system. We demonstrate a simple, non-perturbing method to monitor coiled coil formation using p-cyanophenylalanine (FCN) and selenomethionine (MSe), the Se analogue of Met. FCN fluorescence can be selectively excited and is effectively quenched by electron transfer with MSe. Both FCN and MSe represent minimally perturbing substitutions in coiled coils. MSe quenching of FCN fluorescence is shown to offer a non-perturbing method for following coiled coil formation and for accurately determining dissociation constants. The method is validated using a designed heterodimeric coiled coil. The KD deduced by fluorescence monitored titration is in excellent agreement with the value deduced from concentration dependent CD measurements to within the uncertainty of the measurement. However, the fluorescence approach requires less protein, is less time-consuming, can be applied to lower concentrations and could be applied to high throughput screens.

  11. Behavior of the guanine base in G-quadruplexes probed by the fluorescent guanine analog, 6-methyl isozanthopterin

    Energy Technology Data Exchange (ETDEWEB)

    Han, Ji Hoon; Chitrapriya, Nataraj; Lee, Hyun Suk; Lee, Young Ae; Kim, Seog K. [Dept. of Chemistry, Yeungnam University, Gyeongsan (Korea, Republic of); Jung, Maeng Joon [Dept. of Chemistry, Kyungpook National University, Daegu (Korea, Republic of)

    2017-02-15

    In this study, circular dichroism (CD) spectrum and fluorescence techniques were used to examine the dynamic properties and microenvironment of the guanine base (G) at the central loop and at the middle of the G-stem of the G-quadruplex formed from the G{sub 3}T{sub 2}G{sub 3}TGTG{sub 3}T{sub 2}G{sub 3} sequence (G-quadruplex 1), in which the G base at the 10th and 13th position were replaced with a fluorescent G analog, 6-methyl isoxanthopterin (6MI) (G-quadruplex 2 and 3, respectively). For all G-quadruplexes, the CD spectrum revealed a positive band at 263 nm and a shoulder at 298 nm, and the thermal melting profiles were the sum of at least two sigmoidal curves. These observations indicated the presence of two conformers in the G-quadruplex. The fluorescence intensity of G-quadruplex 2 was greater than 3, as expected from the extent of stacking interaction, which is larger in the G(6MI)G sequence than the T(6MI)T sequence. The efficiency of fluorescence quenching by the polar acrylamide quencher and negatively charged I− quencher were larger for G-quadruplex 3, suggesting that 6MI in the G(6MI)G stem is exposed more to the aqueous environment compared to that in the T(6MI)T central loop. In the latter case, 6MI may direct to the center of the top G-quartet layer. The possibility of hydrogen bond formation between the carbonyl group of 6MI and the acrylamide of the G-quadruplex 3 was proposed.

  12. Quantitative light fluorescence (QLF) and polarized white light (PWL) assessments of dental fluorosis in an epidemiological setting.

    Science.gov (United States)

    Pretty, Iain A; McGrady, Michael; Zakian, Christian; Ellwood, Roger P; Taylor, Andrew; Sharif, Mohammed Owaise; Iafolla, Timothy; Martinez-Mier, E Angeles; Srisilapanan, Patcharawan; Korwanich, Narumanas; Goodwin, Michaela; Dye, Bruce A

    2012-05-20

    To determine if a novel dual camera imaging system employing both polarized white light (PWL) and quantitative light induced fluorescence imaging (QLF) is appropriate for measuring enamel fluorosis in an epidemiological setting. The use of remote and objective scoring systems is of importance in fluorosis assessments due to the potential risk of examiner bias using clinical methods. Subjects were recruited from a panel previously characterized for fluorosis and caries to ensure a range of fluorosis presentation. A total of 164 children, aged 11 years (±1.3) participated following consent. Each child was examined using the novel imaging system, a traditional digital SLR camera, and clinically using the Dean's and Thylstrup and Fejerskov (TF) Indices on the upper central and lateral incisors. Polarized white light and SLR images were scored for both Dean's and TF indices by raters and fluorescence images were automatically scored using software. Data from 164 children were available with a good distribution of fluorosis severity. The automated software analysis of QLF images demonstrated significant correlations with the clinical examinations for both Dean's and TF index. Agreement (measured by weighted Kappa's) between examiners scoring clinically, from polarized photographs and from SLR images ranged from 0.56 to 0.92. The study suggests that the use of a digital imaging system to capture images for either automated software analysis, or remote assessment by raters is suitable for epidemiological work. The use of recorded images enables study archiving, assessment by multiple examiners, remote assessment and objectivity due to the blinding of subject status.

  13. Quantitative Light Fluorescence (QLF and Polarized White Light (PWL assessments of dental fluorosis in an epidemiological setting

    Directory of Open Access Journals (Sweden)

    Pretty Iain A

    2012-05-01

    Full Text Available Abstract Background To determine if a novel dual camera imaging system employing both polarized white light (PWL and quantitative light induced fluorescence imaging (QLF is appropriate for measuring enamel fluorosis in an epidemiological setting. The use of remote and objective scoring systems is of importance in fluorosis assessments due to the potential risk of examiner bias using clinical methods. Methods Subjects were recruited from a panel previously characterized for fluorosis and caries to ensure a range of fluorosis presentation. A total of 164 children, aged 11 years (±1.3 participated following consent. Each child was examined using the novel imaging system, a traditional digital SLR camera, and clinically using the Dean’s and Thylstrup and Fejerskov (TF Indices on the upper central and lateral incisors. Polarized white light and SLR images were scored for both Dean’s and TF indices by raters and fluorescence images were automatically scored using software. Results Data from 164 children were available with a good distribution of fluorosis severity. The automated software analysis of QLF images demonstrated significant correlations with the clinical examinations for both Dean’s and TF index. Agreement (measured by weighted Kappa’s between examiners scoring clinically, from polarized photographs and from SLR images ranged from 0.56 to 0.92. Conclusions The study suggests that the use of a digital imaging system to capture images for either automated software analysis, or remote assessment by raters is suitable for epidemiological work. The use of recorded images enables study archiving, assessment by multiple examiners, remote assessment and objectivity due to the blinding of subject status.

  14. Identification of squid species by melting temperature shifts on fluorescence melting curve analysis (FMCA) using single dual-labeled probe

    Science.gov (United States)

    Koh, Eunjung; Song, Ha Jeong; Kwon, Na Young; Kim, Gi Won; Lee, Kwang Ho; Jo, Soyeon; Park, Sujin; Park, Jihyun; Park, Eun Kyeong; Hwang, Seung Yong

    2017-06-01

    Real time PCR is a standard method for identification of species. One of limitations of the qPCR is that there would be false-positive result due to mismatched hybridization between target sequence and probe depending on the annealing temperature in the PCR condition. As an alternative, fluorescence melting curve analysis (FMCA) could be applied for species identification. FMCA is based on a dual-labeled probe. Even with subtle difference of target sequence, there are visible melting temperature (Tm) shift. One of FMCA applications is distinguishing organisms distributed and consumed globally as popular food ingredients. Their prices are set by species or country of origin. However, counterfeiting or distributing them without any verification procedure are becoming social problems and threatening food safety. Besides distinguishing them in naked eye is very difficult and almost impossible in any processed form. Therefore, it is necessary to identify species in molecular level. In this research three species of squids which have 1-2 base pair differences each are selected as samples since they have the same issue. We designed a probe which perfectly matches with one species and the others mismatches 2 and 1 base pair respectively and labeled with fluorophore and quencher. In an experiment with a single probe, we successfully distinguished them by Tm shift depending on the difference of base pair. By combining FMCA and qPCR chip, smaller-scale assay with higher sensitivity and resolution could be possible, andc furthermore, enabling results analysis with smart phone would realize point-of-care testing (POCT).

  15. Probing the Accretion Processes in Soft X-Ray Selected Polars

    Directory of Open Access Journals (Sweden)

    I. Traulsen

    2015-02-01

    Full Text Available High-energy data of accreting white dwarfs give access to the regime of the primary accretion-induced energy release and the different proposed accretion scenarios. We perform XMM-Newton observations of polars selected due to their ROSAT hardness ratios close to -1.0 and model the emission processes in accretion column and accretion region. Our models consider the multi-temperature structure of the emission regions and are mainly determined by mass-flow density, magnetic field strength, and white-dwarf mass. To describe the full spectral energy distribution from infrared to X-rays in a physically consistent way, we include the stellar contributions and establish composite models, which will also be of relevance for future X-ray missions. We confirm the X-ray soft nature of three polars.

  16. A Polarized Drell-Yan Experiment to Probe the Dynamics of the Nucleon Sea

    Energy Technology Data Exchange (ETDEWEB)

    Kleinjan, David William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-26

    After presenting the nucleon spin puzzle as motivation for the experiment, the authors turn to a theoretical overview: sea quark flavor asymmetry and meson cloud model, and accessing quark angular momentum via the Sivers function. Then they describe the experimental equipment and conditions needed to carry out a fixed, polarized target Drell-Yan experiment, E1039. Data taking is expected to start in the middle of 2016.

  17. Two-dimensional spatially ordered system of nickel nanowires probed by polarized SANS

    International Nuclear Information System (INIS)

    Napolskii, K.S.; Chumakov, A.P.; Grigoriev, S.V.; Grigoryeva, N.A.; Eckerlebe, H.; Eliseev, A.A.; Lukashin, A.V.; Tretyakov, Yu.D.

    2009-01-01

    Structural and magnetic properties of two-dimensional spatially ordered system of ferromagnetic nickel nanowires embedded into Al 2 O 3 matrix have been studied using polarized small-angle neutron scattering. The small-angle diffraction pattern exhibits many diffraction peaks, which corresponds to the scattering from highly correlated hexagonal structure of pores and magnetic nanowires. Magnetic contribution to the scattering has complex behavior and cannot be explained without taking into account stray fields located between magnetized nanowires.

  18. NMR in an electric field: A bulk probe of the hidden spin and orbital polarizations

    OpenAIRE

    Ramírez-Ruiz, Jorge; Boutin, Samuel; Garate, Ion

    2017-01-01

    Recent theoretical work has established the presence of hidden spin and orbital textures in non-magnetic materials with inversion symmetry. Here, we propose that these textures can be detected by nuclear magnetic resonance (NMR) measurements carried out in the presence of an electric field. In crystals with hidden polarizations, a uniform electric field produces a staggered magnetic field that points to opposite directions at atomic sites related by spatial inversion. As a result, the NMR res...

  19. A fast-responsive fluorescent probe based on BODIPY dye for sensitive detection of hypochlorite and its application in real water samples.

    Science.gov (United States)

    Wang, Yun; Xia, Jinchen; Han, Juan; Bao, Xu; Li, Yuanyuan; Tang, Xu; Ni, Liang; Wang, Lei; Gao, Mengmeng

    2016-12-01

    Hypochlorite serves as a powerful antimicrobial agent in human immune system, the detection of which is of great significance. Herein a novel fluorescent probe based on BODIPY dye and diaminomaleonitrile has been synthesized and characterized to sense hypochlorite. The fluorescence of the system is dramatically enhanced by ClO - due to the removal of C=N isomerization effect in physiological pH condition. The complete reaction only needs a few seconds, which enables the probe to facilitate real-time detection. This probe also has satisfactory selectivity for ClO - even in the presence of other interferential ions and shows high sensitivity with a detection limit of 19.8nM. Furthermore, Probe 1 has been successfully applied to detect ClO - in real water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. A Rotational BODIPY Nucleotide: An Environment-Sensitive Fluorescence-Lifetime Probe for DNA Interactions and Applications in Live-Cell Microscopy

    Czech Academy of Sciences Publication Activity Database

    Dziuba, Dmytro; Jurkiewicz, Piotr; Cebecauer, Marek; Hof, Martin; Hocek, Michal

    2016-01-01

    Roč. 55, č. 1 (2016), s. 174-178 ISSN 1433-7851 R&D Projects: GA ČR GBP206/12/G151; GA ČR(CZ) GC14-03141J Institutional support: RVO:61388963 ; RVO:61388955 Keywords : DNA * fluorescence spectroscopy * fluorescent probes * nucleosides * time-resolved spectroscopy Subject RIV: CC - Organic Chemistry; BO - Biophysics (UFCH-W) Impact factor: 11.994, year: 2016

  1. Characterization of a fluorescence probe based on gold nanoclusters for cell and animal imaging

    International Nuclear Information System (INIS)

    Chen Haiyan; Zhang Xin; Cheng Zhengqi; Dai Xi; Zhu Rui; Gu Yueqing; Li Bowen; Wang Chuan

    2013-01-01

    A facile approach to synthesize gold nanoclusters (Au NCs) with bluish green fluorescence using histidine as both reductant and capping agent was reported. The UV–visible absorption and photoluminescence spectra measurement was performed to explore its optical properties under different circumstances (preparing condition, temperature, pH, storing time). Then, MPA, a NIR organic dye, was conjugated to Au NCs (Au-MPA) for in vivo fluorescence imaging application. Low cytotoxicity and high affinity to tumor of this nanoprobe was proved at the cellular level, and its bio-distribution in normal nude mice and MCF-7 tumor-bearing mice was also investigated. Consequently, the results demonstrated the promising potential of the green Au NCs conjugated with NIR dye as nanoprobes in bioimaging and related fields. (paper)

  2. Probing into the Interaction of Nicotine and Bovine Submaxillary Mucin: NMR, Fluorescence, and FTIR Approaches

    Directory of Open Access Journals (Sweden)

    Xiaoxiang Liao

    2016-01-01

    Full Text Available Nicotine, the important component of cigarette products, may have an impact on the oral environment after inhalation. The research of interaction between nicotine and bovine submaxillary mucin (BSM contributes to understand the binding mechanism of nicotine and BSM, and the effects of nicotine on the structure and function of the mucin. NMR data demonstrated that the interaction between nicotine and BSM did exist, and it was pyrrolidyl ring of nicotine playing the major role in the binding. The quenching mechanisms of nicotine and BSM in different pH were different: for acidic environment, the quenching was dynamic; while it became static in the alkaline circumstance. Synchronous fluorescence spectra indicated that nicotine had effect on the microenvironment of the Trp rather than Tyr residue. Meanwhile, the impact of nicotine on the conformation of BSM was also confirmed by 3D fluorescence and FTIR spectra.

  3. Carbon dots prepared from citric acid and urea as fluorescent probes for hypochlorite and peroxynitrite

    International Nuclear Information System (INIS)

    Simões, Eliana F. C.; Leitão, João M. M.; Esteves da Silva, Joaquim C. G.

    2016-01-01

    Carbon dots (CDs) were prepared from citric acid and urea, and their fluorescence was found to be quenched by hypochlorite and peroxynitrite. Microwave based synthesis gives CDs with excitation/emission wavelength-dependent quantum yields (8 % at 400/520 nm; 10 % at 360/451 nm; 12 % at 350/420 nm). Quenching of fluorescence depends on pH values, and response is most selective and sensitive to hypochlorite at pH 4, and to peroxynitrite at pH 9. The lower detection limits are 0.5 and 1.5 μM, respectively. The method was successfully applied to quantify hypochlorite and peroxynitrite in standard solutions and in spiked dilute serum samples. (author)

  4. Selective Labeling of Proteins on Living Cell Membranes Using Fluorescent Nanodiamond Probes

    Directory of Open Access Journals (Sweden)

    Shingo Sotoma

    2016-03-01

    Full Text Available The impeccable photostability of fluorescent nanodiamonds (FNDs is an ideal property for use in fluorescence imaging of proteins in living cells. However, such an application requires highly specific labeling of the target proteins with FNDs. Furthermore, the surface of unmodified FNDs tends to adsorb biomolecules nonspecifically, which hinders the reliable targeting of proteins with FNDs. Here, we combined hyperbranched polyglycerol modification of FNDs with the β-lactamase-tag system to develop a strategy for selective imaging of the protein of interest in cells. The combination of these techniques enabled site-specific labeling of Interleukin-18 receptor alpha chain, a membrane receptor, with FNDs, which eventually enabled tracking of the diffusion trajectory of FND-labeled proteins on the membrane surface.

  5. Aggregation induced emission enhancement (AIEE) characteristics of quinoline based compound - A versatile fluorescent probe for pH, Fe(III) ion, BSA binding and optical cell imaging

    Science.gov (United States)

    Manikandan, Irulappan; Chang, Chien-Huei; Chen, Chia-Ling; Sathish, Veerasamy; Li, Wen-Shan; Malathi, Mahalingam

    2017-07-01

    Novel benzimidazoquinoline derivative (AVT) was synthesized through a substitution reaction and characterized by various spectral techniques. Analyzing the optical properties of AVT under absorption and emission spectral studies in different environments exclusively with respect to solvents and pH, intriguing characteristics viz. aggregation induced emission enhancement (AIEE) in the THF solvent and 'On-Off' pH sensing were found at neutral pH. Sensing nature of AVT with diverse metal ions and bovine serum albumin (BSA) was also studied. Among the metal ions, Fe3 + ion alone tunes the fluorescence intensity of AVT probe in aqueous medium from ;turn-on; to ;turn-off; through ligand (probe) to metal charge transfer (LMCT) mechanism. The probe AVT in aqueous medium interacts strongly with BSA due to Fluorescence Resonance Energy Transfer (FRET) and the conformational change in BSA was further analyzed using synchronous fluorescence techniques. Docking study of AVT with BSA reveals that the active site of binding is tryptophan residue which is also supported by the experimental results. Interestingly, fluorescent AVT probe in cells was examined through cellular imaging studies using BT-549 and MDA-MB-231 cells. Thus, the single molecule probe based detection of multiple species and stimuli were described.

  6. Hydrogen sulfide and resolution of acute inflammation: A comparative study utilizing a novel fluorescent probe

    OpenAIRE

    Dufton, Neil; Natividad, Jane; Verdu, Elena F.; Wallace, John L.

    2012-01-01

    Hydrogen sulfide is an essential gasotransmitter associated with numerous pathologies. We assert that hydrogen sulfide plays an important role in regulating macrophage function in response to subsequent inflammatory stimuli, promoting clearance of leukocyte infiltrate and reducing TNF-α levels in vivo following zymosan-challenge. We describe two distinct methods of measuring leukocyte hydrogen sulfide synthesis; methylene blue formation following zinc acetate capture and a novel fluorescent s...

  7. Determination of heavy metals in polar snow and ice by laser-excited atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    Bolshov, M.A.; Boutron, C.F.

    1994-01-01

    The new laser-excited atomic fluorescence spectrometry technique offers unrivalled sensitivity for the determination of trace metals in a wide variety of samples. This has allowed the direct determination of Pb, Cd and Bi in Antarctic and Greenland snow and ice down to the sub pg/g level. (authors). 11 refs., 2 figs

  8. mathFISH, a web tool that uses thermodynamics-based mathematical models for in silico evaluation of oligonucleotide probes for fluorescence in situ hybridization.

    Science.gov (United States)

    Yilmaz, L Safak; Parnerkar, Shreyas; Noguera, Daniel R

    2011-02-01

    Mathematical models of RNA-targeted fluorescence in situ hybridization (FISH) for perfectly matched and mismatched probe/target pairs are organized and automated in web-based mathFISH (http://mathfish.cee.wisc.edu). Offering the users up-to-date knowledge of hybridization thermodynamics within a theoretical framework, mathFISH is expected to maximize the probability of success during oligonucleotide probe design.

  9. A Pyrene- and Phosphonate-Containing Fluorescent Probe as Guest Molecule in a Host Polymer Matrix

    Directory of Open Access Journals (Sweden)

    Jacqueline Marchand-Brynaert

    2013-02-01

    Full Text Available New host-guest materials have been prepared by incorporation of a home-made organic probe displaying a pyrene motif and a phosphonate function into a regular amphiphilic copolymer. Using powder X-Ray diffraction, photoluminescence and FT-IR spectroscopy, we have been able to study the non-covalent interactions between the host matrix and the guest molecule in the solid state. Interestingly, we have shown that the matrix directs the guest spatial localization and alters its properties. Thanks to the comparison of pyrene vs. N-pyrenylmaleimide derivatives, the influence of the chemical nature of the guest molecules on the non-covalent interactions with the host have been studied. In addition, using polyethylene glycol as a reference host, we have been able to evidence a true matrix effect within our new insertion materials. The phosphonated guest molecule appears to be a novel probe targeting the hydrophilic domain of the host copolymer.

  10. Dual imaging probes for magnetic resonance imaging and fluorescence microscopy based on perovskite manganite nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Kačenka, M.; Kaman, Ondřej; Kotek, J.; Falteisek, L.; Černý, J.; Jirák, D.; Herynek, V.; Zacharovová, K.; Berková, A.; Jendelová, Pavla; Kupčík, Jaroslav; Pollert, Emil; Veverka, Pavel; Lukeš, I.

    2011-01-01

    Roč. 21, č. 1 (2011), s. 157-164 ISSN 0959-9428 R&D Projects: GA AV ČR KAN200200651 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z50390703; CEZ:AV0Z40720504 Keywords : cellular labelling * dual probe * magnetic nanoparticles * MRI * silica coating Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.968, year: 2011

  11. Tungsten disulfide nanosheet and exonuclease III co-assisted amplification strategy for highly sensitive fluorescence polarization detection of DNA glycosylase activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jingjin; Ma, Yefei [Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources of Education Ministry, Guangxi Normal University, Guilin, 541004 (China); Kong, Rongmei [The Key Laboratory of Life-Organic Analysis, College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165 (China); Zhang, Liangliang, E-mail: liangzhang319@163.com [Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources of Education Ministry, Guangxi Normal University, Guilin, 541004 (China); Yang, Wen; Zhao, Shulin [Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources of Education Ministry, Guangxi Normal University, Guilin, 541004 (China)

    2015-08-05

    Herein, we introduced a tungsten disulfide (WS{sub 2}) nanosheet and exonuclease III (Exo III) co-assisted signal amplification strategy for highly sensitive fluorescent polarization (FP) assay of DNA glycosylase activity. Two DNA glycosylases, uracil-DNA glycosylase (UDG) and human 8-oxoG DNA glycosylase 1 (hOGG1), were tested. A hairpin-structured probe (HP) which contained damaged bases in the stem was used as the substrate. The removal of damaged bases from substrate by DNA glycosylase would lower the melting temperature of HP. The HP was then opened and hybridized with a FAM dye-labeled single strand DNA (DP), generating a duplex with a recessed 3′-terminal of DP. This design facilitated the Exo III-assisted amplification by repeating the hybridization and digestion of DP, liberating numerous FAM fluorophores which could not be adsorbed on WS{sub 2} nanosheet. Thus, the final system exhibited a small FP signal. However, in the absence of DNA glycosylases, no hybridization between DP and HP was occurred, hampering the hydrolysis of DP by Exo III. The intact DP was then adsorbed on the surface of WS{sub 2} nanosheet that greatly amplified the mass of the labeled-FAM fluorophore, resulting in a large FP value. With the co-assisted amplification strategy, the sensitivity was substantially improved. In addition, this method was applied to detect UDG activity in cell extracts. The study of the inhibition of UDG was also performed. Furthermore, this method is simple in design, easy in implementation, and selective, which holds potential applications in the DNA glycosylase related mechanism research and molecular diagnostics. - Highlights: • A fluorescence polarization strategy for DNA glycosylase activity detection was developed. • The present method was based on WS{sub 2} nanosheet and exonuclease III co-assisted signal amplification. • A high sensitivity and desirable selectivity were achieved. • This method provides a promising universal platform for DNA

  12. Automated system to acquire fluorescence, polarization and anisotropy maps within liquid flows.

    Science.gov (United States)

    Quintella, Cristina M; Gonçalves, Cristiane C; Pepe, Iuri; Lima, Angelo M V; Musse, Ana Paula S

    2002-01-01

    Maps of polarization and anisotropy can be helpful for flow analysis systems (FIA, CFA, etc.) with reactions dependent on the intermolecular alignment as well as for dispersion control. Maps can be acquired manually, but when a scan over a sample area is required, the acquisition becomes tiresome and has low precision. The paper describes an automatic flexible system for high-precision sample positioning with closed loop self control, remote data acquisition and storage controlled by a BASIC program. The system was developed to acquire maps up to 850 mm(2) of the sample (liquid flows, solids, interfaces, etc.), with up to 100 mum(2) precision. To evaluate the equipment, performance is presented as the scan of a thin liquid film of monoethylene glycol (MEG) flowing on borosilicate. Tests were performed with and without surfactantes at submicellar concentrations: two concentrations of sodium dodecyl sulphate (SDS) and one of polyethylene oxide (PEO). For pure MEG, the intermolecular alignment initially increased, then decreased. When SDS was added, both polarization and anisotropy only increased progressively with the flow. This might be explained by the surfactant decrease of interfacial interaction. When PEO was added, both polarization and anisotropy decreased pronouncedly over the entire map, which might be due to macromolecular aggregates within the bulk generating misaligned molecular domains. The system presented as sample positioning repeatability of 0.1% and a high polarization reproducibility (error margin < 6 in 1000).

  13. Recent progress in the development of fluorescent, luminescent and colorimetric probes for detection of reactive oxygen and nitrogen species.

    Science.gov (United States)

    Chen, Xiaoqiang; Wang, Fang; Hyun, Ji Young; Wei, Tingwen; Qiang, Jian; Ren, Xintong; Shin, Injae; Yoon, Juyoung

    2016-05-21

    Reactive oxygen (ROS) and nitrogen (RNS) species cause oxidative and nitrosative stresses, respectively. These stresses are implicated not only in diverse physiological processes but also in various pathological processes, including cancer and neurodegenerative disorders. In addition, some ROS and RNS in the environment are pollutants that threaten human health. As a consequence of these effects, sensitive methods, which can be employed to selectively monitor ROS and RNS in live cells, tissues and organisms as well as in environmental samples, are needed so that their biological roles can be understood and their concentrations in environmental samples can be determined. In this review, fluorescent, luminescent and colorimetric ROS and RNS probes, which have been developed since 2011, are comprehensively discussed.

  14. Novel lanthanide pH fluorescent probes based on multiple emissions and its visible-light-sensitized feature

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jintai [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Zheng, Yuhui, E-mail: yhzheng78@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Wang, Qianming, E-mail: qmwang@scnu.edu.cn [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Guangzhou Key Laboratory of Materials for Energy Conversion and Storage, Guangzhou 510006 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Zeng, Zhi [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Zhang, Cheng Cheng [Departments of Physiology and Developmental Biology, University of Texas Southwestern Medical Center, Dallas (United States)

    2014-08-11

    Graphical abstract: A new type of Eu(III) ofloxacin complex as the fluorescent pH indicator has been reported. Compared to pure ligand, the complex offers more distinguished color changes (green–red–blue) derived from both lanthanide line emissions and the secondary ionization steps of ofloxacin. - Highlights: • The pH probe offers a very wide working range in water (pH 1–14). • The emission changes have multiple colors. • Long-lived excited state lifetimes of Eu(III) has been used. • Two types of pH sensitive hydrogels were fabricated. - Abstract: A new type of Eu(III) ofloxacin complex as the fluorescent pH indicator has been presented. Compared to pure ligand, the complex offers more distinguished color changes (green–red–blue) derived from both lanthanide line emissions and the secondary ionization steps of ofloxacin. During the concentration dependence experiments, the photoluminescence studies on the complex showed that the excitation of this pH probe can occur at a very long wavelength which extends to visible range (Ex = 427 nm). Furthermore, the functional complex was successfully incorporated into soft networks and two novel luminescent hydrogels (rod and film) were fabricated. The soft materials also exhibited specific responses towards the pH variation. Finally, the onion cell-stain experiments were carried out to further confirm the validity of pH dependence and the results support the idea that the material will be suitable for monitoring biological samples in the future.

  15. Utilization of fluorescent probe association for simultaneous assessment of plasmatic, acrosomal, and mitochondrial membranes of rooster spermatozoa

    Directory of Open Access Journals (Sweden)

    ECC Celeghini

    2007-09-01

    Full Text Available This experiment was designed with the objective of developing a simple, practical, and high repeatability technique for the simultaneous evaluation of the integrity of the plasmatic and acrosomal membranes, as well as funcional mitochondria of domestic fowl spermatozoa using an association of fluorescent probes. Four ejaculates (motility > 80% and abnormal morphology < 10% from each of six Ross male broiler breeder (n=24 were diluted in TALP sperm medium (25x10(6 spermatozoa/mL and split into two aliquots, and one of these aliquots was flash frozen in liquid nitrogen and thawed to damage all cellular membranes. Three treatments were prepared from these aliquots, with the following ratios of Fresh semen:Flash frozen semen: 100:0 (T100, 50:50 (T50, and 0:100 (T0. A 150-µL aliquot of diluted semen was placed in a microcentrifuge tube with the addition of 2-µL PI, 2-µL MITO, and 50-µL FITC-PSA, and incubated at 38.5º C/8 min in the dark. An 8-µL sample was placed on a slide, coverslipped, and examined by epifluorescence microscopy. Each sample had 200 cells counted and classified based on the fluorescence emitted by each probe. By regression analysis, plasma membrane integrity, as detected by PI, was determined as: v=4.17+0.82X (R²=0.95. Acrosome integrity, as detected by FITC-PSA, generated the equation: v=4.19+0.84X (R²=0.96. Functional mitochondria was estimated by the equation v=3.20+0.83X (R²=0.96. This is an efficient technique to simultaneously evaluate plasmatic, acrosomal, and mitochondrial membranes in fowl sperm. It is suggested that its application in flow cytometry systems allows this methodology to be applied in large scale.

  16. Antiferromagnetic Spin Coupling between Rare Earth Adatoms and Iron Islands Probed by Spin-Polarized Tunneling.

    Science.gov (United States)

    Coffey, David; Diez-Ferrer, José Luis; Serrate, David; Ciria, Miguel; de la Fuente, César; Arnaudas, José Ignacio

    2015-09-03

    High-density magnetic storage or quantum computing could be achieved using small magnets with large magnetic anisotropy, a requirement that rare-earth iron alloys fulfill in bulk. This compelling property demands a thorough investigation of the magnetism in low dimensional rare-earth iron structures. Here, we report on the magnetic coupling between 4f single atoms and a 3d magnetic nanoisland. Thulium and lutetium adatoms deposited on iron monolayer islands pseudomorphically grown on W(110) have been investigated at low temperature with scanning tunneling microscopy and spectroscopy. The spin-polarized current indicates that both kind of adatoms have in-plane magnetic moments, which couple antiferromagnetically with their underlying iron islands. Our first-principles calculations explain the observed behavior, predicting an antiparallel coupling of the induced 5d electrons magnetic moment of the lanthanides with the 3d magnetic moment of iron, as well as their in-plane orientation, and pointing to a non-contribution of 4f electrons to the spin-polarized tunneling processes in rare earths.

  17. Probing the interaction mechanisms between transmembrane peptides and the chaperonin GroEL with fluorescence anisotropy

    Science.gov (United States)

    Wang, Xiaoqiang; Chen, Han; Lu, Xinwei; Chi, Haixia; Li, Shixin; Huang, Fang

    2018-04-01

    Proper translocation, membrane insertion and folding are crucial biophysical steps in the biogenesis of functional transmembrane peptides/proteins (TMPs). ATP-dependent chaperonins are able to regulate each of these processes, but the underlying mechanisms remain unclear. In this work, interaction between the bacterial chaperonin GroEL and a synthetic fluorescent transmembrane peptide was investigated by fluorescence anisotropy. Binding of the peptide with GroEL resulted in increased fluorescence anisotropy and intensity. The dissociation constant and binding stoichiometry, as assessed by titration of the peptide with GroEL, were estimated to be 0.6 ± 0.2 μM and 2.96 ± 0.35, respectively. Complementary study with the single-ring version of GroEL confirmed the high-affinity peptide binding, and indicates that the two GroEL rings may function alternatively in binding the peptides. The co-chaperonin GroES was found to be effective at releasing the peptides initially bound to GroEL with the help of ATP. Moreover, our observation with the single-ring GroEL mutant demonstrated that during the encapsulation of GroEL by GroES, the bound peptides may either be confined in the cage thus formed, or escape outside. Competitive binding experiments indicated that the peptides studied interact with GroEL through the paired helices H and I on its apical domain. Our spectroscopic studies revealed some basic mechanisms of interaction between transmembrane peptides and GroEL, which would be instrumental for deciphering the chaperonin-mediated TMP biogenesis.

  18. Multimodality Imaging Probe for Positron Emission Tomography and Fluorescence Imaging Studies

    Directory of Open Access Journals (Sweden)

    Suresh K. Pandey

    2014-05-01

    Full Text Available Our goal is to develop multimodality imaging agents for use in cell tracking studies by positron emission tomography (PET and optical imaging (OI. For this purpose, bovine serum albumin (BSA was complexed with biotin (histologic studies, 5(6- carboxyfluorescein, succinimidyl ester (FAM SE (OI studies, and diethylenetriamine pentaacetic acid (DTPA for chelating gallium 68 (PET studies. For synthesis of BSA-biotin-FAM-DTPA, BSA was coupled to (+-biotin N-hydroxysuccinimide ester (biotin-NHSI. BSA- biotin was treated with DTPA-anhydride and biotin-BSA-DTPA was reacted with FAM. The biotin-BSA-DTPA-FAM was reacted with gallium chloride 3 to 5 mCi eluted from the generator using 0.1 N HCl and was passed through basic resin (AG 11 A8 and 150 mCi (100 μL, pH 7–8 was incubated with 0.1 mg of FAM conjugate (100 μL at room temperature for 15 minutes to give 66Ga-BSA-biotin-DTPA-FAM. A shaved C57 black mouse was injected with FAM conjugate (50 μL at one flank and FAM-68Ga (50 μL, 30 mCi at the other. Immediately after injection, the mouse was placed in a fluorescence imaging system (Kodak In-Vivo F, Bruker Biospin Co., Woodbridge, CT and imaged (Λex: 465 nm, Λem: 535 nm, time: 8 seconds, Xenon Light Source, Kodak. The same mouse was then placed under an Inveon microPET scanner (Siemens Medical Solutions, Knoxville, TN injected (intravenously with 25 μCi of 18F and after a half-hour (to allow sufficient bone uptake was imaged for 30 minutes. Molecular weight determined using matrix-associated laser desorption ionization (MALDI for the BSA sample was 66,485 Da and for biotin-BSA was 67,116 Da, indicating two biotin moieties per BSA molecule; for biotin-BSA-DTPA was 81,584 Da, indicating an average of 30 DTPA moieties per BSA molecule; and for FAM conjugate was 82,383 Da, indicating an average of 1.7 fluorescent moieties per BSA molecule. Fluorescence imaging clearly showed localization of FAM conjugate and FAM-68Ga at respective flanks of the mouse

  19. Biofunctional quantum dots as fluorescence probe for cell-specific targeting

    OpenAIRE

    Ag, Didem; Bongartz, Rebecca; Dogan, Leyla Eral; Seleci, Muharrem; Walter, Johanna-Gabriela; Demirkol, Dilek Odaci; Stahl, Frank; Ozcelik, Serdar; Timur, Suna; Scheper, Thomas

    2014-01-01

    We describe here the synthesis, characterization, bioconjugation, and application of water-soluble thioglycolic acid TGA-capped CdTe/CdS quantum dots (TGA-QDs) for targeted cellular imaging. Anti-human epidermal growth factor receptor 2 (HER2) antibodies were conjugated to TGA-QDs to target HER2-overexpressing cancer cells. TGA-QDs and TGA-QDs/anti-HER2 bioconjugates were characterized by fluorescence and UV-Vis spectroscopy, X-ray diffraction (XRD), hydrodynamic sizing, electron microscopy, ...

  20. Effect of pressure on interactions of anti-fluorescent probe monoclonal antibody with a ligand and inhibitors

    International Nuclear Information System (INIS)

    Nishimoto, M; Kaneshina, S; Goto, M; Tamai, N; Nagamune, H; Matsuki, H

    2010-01-01

    Interactions of anti-fluorescent probe monoclonal antibody (immunoglobulin G (IgG)-49) with a ligand (fluorescein (FL)) and three kinds of inhibitors (1-tetradecanol (C14OH), 1-tetradecanoic acid (C13COOH) and 5-aminofluorescein (5-FLNH 2 )) under high pressure were examined by methods of fluorescence spectroscopy. Pressure promoted the dissociation between FL and IgG-49 from the complex. The standard volume changes of the dissociation became negative, hence, the binding of FL to IgG-49 expands the volume of the complex. The volume expansion may be closely related to the large hydrophobicity around binding sites of FL in the IgG-49 molecule. Further, the standard volume changes of IgG-49 for the inhibitor binding, which were calculated from the Johnson-Eyring plots, became all negative. The volume change for 5-FLNH 2 was smaller than those for C14OH and C13COOH. This means that the volume of IgG-49 shrinks by the addition of the inhibitors in contrast with the FL binding. The differences among inhibitors are attributable to the differences in interaction modes to IgG-49 among them.

  1. Efficient and Scalable Synthesis of 4-Carboxy-Pennsylvania Green Methyl Ester: A Hydrophobic Building Block for Fluorescent Molecular Probes.

    Science.gov (United States)

    Woydziak, Zachary R; Fu, Liqiang; Peterson, Blake R

    2014-01-01

    Fluorinated fluorophores are valuable tools for studies of biological systems. However, amine-reactive single-isomer derivatives of these compounds are often very expensive. To provide an inexpensive alternative, we report a practical synthesis of 4-carboxy-Pennsylvania Green methyl ester. Derivatives of this hydrophobic fluorinated fluorophore, a hybrid of the dyes Oregon Green and Tokyo Green, are often cell permeable, enabling labeling of intracellular targets and components. Moreover, the low pKa of Pennsylvania Green (4.8) confers bright fluorescence in acidic cellular compartments such as endosomes, enhancing its utility for chemical biology investigations. To improve access to the key intermediate 2,7-difluoro-3,6-dihydroxyxanthen-9-one, we subjected bis-(2,4,5-trifluorophenyl)methanone to iterative nucleophilic aromatic substitution by hydroxide on scales of > 40 g. This intermediate was used to prepare over 15 grams of pure 4-carboxy-Pennsylvania Green methyl ester in 28% overall yield without requiring chromatography. This compound can be converted into the amine reactive N -hydroxysuccinimidyl ester in essentially quantitative yield for the synthesis of a wide variety of fluorescent molecular probes.

  2. Photoacoustic imaging of a near-infrared fluorescent marker based on dual wavelength pump-probe excitation

    Science.gov (United States)

    Märk, Julia; Theiss, Christoph; Schmitt, Franz-Josef; Laufer, Jan

    2014-03-01

    Photoacoustic imaging has been used to determine the spatial distribution of fluorophores, such as exogenous dyes and genetically expressed proteins, from images acquired in phantoms and in vivo. Most methods involve the acquisition of multiwavelength images and rely on differences in the absorption spectra of the tissue chromophores to estimate the spatial distribution and abundance of the latter using spectral decomposition techniques, such as model based inversion schemes. However, the inversion of 3-D images can be computationally expensive. Experimental approaches to localising contrast agents may therefore be useful, especially if quantification is not essential. This work aims to develop a method for determining the spatial distribution of a near-infrared fluorescent cell marker from images acquired using dual wavelength excitation. The excitation wavelengths coincided with the absorption and emission spectrum of the fluorophore. The contrast mechanism relies on reducing the excited state lifetime of the fluorophore by inducing stimulated emission. This changes the amount of energy thermalized by the fluorophore, and hence the photoacoustic signal amplitude. Since this is not observed in endogenous chromophores, the background may be removed by subtracting two images acquired with and without pulse delay between the pump and probe pulses. To characterise the fluorophore, the signal amplitude is measured in a cuvette as a function of pulse delay, concentration, and fluence. The spatial distribution of the fluorophore is determined from images acquired in realistic tissue phantoms. This method may be suitable for in vivo applications, such as imaging of exogenous or genetically expressed fluorescent cell markers.

  3. Curcumin as fluorescent probe for directly monitoring in vitro uptake of curcumin combined paclitaxel loaded PLA-TPGS nanoparticles

    International Nuclear Information System (INIS)

    Nguyen, Hoai Nam; Ha, Phuong Thu; Do, Hai Doan; Nguyen, Anh Sao; Nguyen, Dac Tu; Thi, Quy Nguyen; Thi, My Nhung Hoang

    2016-01-01

    Theranostics, which is the combination of both therapeutic and diagnostic capacities in one dose, is a promising tool for both clinical application and research. Although there are many chromophores available for optical imaging, their applications are limited due to the photobleaching property or intrinsic toxicity. Curcumin, a natural compound extracted from the rhizome of curcuma longa, is well known thanks to its bio-pharmaceutical activities and strong fluorescence as biocompatible probe for bio-imaging. In this study, we aimed to fabricate a system with dual functions: diagnostic and therapeutic, based on poly(lactide)-tocopheryl polyethylene glycol succinate (PLA-TPGS) micelles co-loaded curcumin (Cur) and paclitaxel (PTX). Two kinds of curcumin nanoparticle (NP) were fabricated and characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy and dynamic light scattering methods. The cellular uptake and fluorescent activities of curcumin in these systems were also tested by bioassay studies, and were compared with paclitaxe-oregon. The results showed that (Cur + PTX)-PLA-TPGS NPs is a potential system for cancer theranostics. (paper)

  4. Curcumin as fluorescent probe for directly monitoring in vitro uptake of curcumin combined paclitaxel loaded PLA-TPGS nanoparticles

    Science.gov (United States)

    Nguyen, Hoai Nam; Thu Ha, Phuong; Sao Nguyen, Anh; Nguyen, Dac Tu; Doan Do, Hai; Nguyen Thi, Quy; Nhung Hoang Thi, My

    2016-06-01

    Theranostics, which is the combination of both therapeutic and diagnostic capacities in one dose, is a promising tool for both clinical application and research. Although there are many chromophores available for optical imaging, their applications are limited due to the photobleaching property or intrinsic toxicity. Curcumin, a natural compound extracted from the rhizome of curcuma longa, is well known thanks to its bio-pharmaceutical activities and strong fluorescence as biocompatible probe for bio-imaging. In this study, we aimed to fabricate a system with dual functions: diagnostic and therapeutic, based on poly(lactide)-tocopheryl polyethylene glycol succinate (PLA-TPGS) micelles co-loaded curcumin (Cur) and paclitaxel (PTX). Two kinds of curcumin nanoparticle (NP) were fabricated and characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy and dynamic light scattering methods. The cellular uptake and fluorescent activities of curcumin in these systems were also tested by bioassay studies, and were compared with paclitaxe-oregon. The results showed that (Cur + PTX)-PLA-TPGS NPs is a potential system for cancer theranostics.

  5. Isostructural fluorescent and radioactive probes for monitoring neural stem and progenitor cell transplants

    Energy Technology Data Exchange (ETDEWEB)

    Schaffer, Paul [McMaster Nuclear Reactor, McMaster University, Hamilton, Ontario, L8S 4K1 (Canada); Gleave, Jacqueline A. [Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, L8N 3Z5 (Canada); Lemon, Jennifer A. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4K1 (Canada); Reid, Leslie C. [Department of Chemistry, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada); Pacey, Laura K.K. [Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, L8N 3Z5 (Canada); Farncombe, Troy H. [Department of Nuclear Medicine, Hamilton Health Sciences, Hamilton, Ontario, L8N 3Z5 (Canada); Boreham, Douglas R. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4K1 (Canada); Zubieta, Jon [Department of Chemistry, Syracuse University, Syracuse, NY 13244-4100 (United States); Babich, John W. [Molecular Insight Pharmaceuticals Inc., Cambridge, MA 02142 (United States); Doering, Laurie C. [Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, L8N 3Z5 (Canada); Valliant, John F. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4K1 (Canada); Department of Chemistry, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada)], E-mail: valliant@mcmaster.ca

    2008-02-15

    A construct for tagging neurospheres and monitoring cell transplantations was developed using a new technology for producing luminescent and radiolabeled probes that have identical structures. The HIV1-Tat basic domain derivatives NAcGRKKRRQRRR(SAACQ)G (SAACQ-1) and [NAcGRKKRRQRRR(Re(CO){sub 3}SAACQ)G]{sup +} (ReSAACQ-1) were prepared in excellent yields using the single amino acid chelate-quinoline (SAACQ) ligand and its Re(I) complex and conventional automated peptide synthesis methods. The distribution of the luminescent Re probe, using epifluorescence microscopy, showed that it localized primarily in the cell nucleus with a significant degree of association on the nuclear envelope. A smaller amount was found to be dispersed in the cytoplasm. The {sup 99m}Tc analogue was then prepared in 43{+-}7% (n=12) yield and very high effective specific activity. Following incubation, average uptake of the probe in neurospheres ranged between 10 and 20 Bq/cell. As determined by colorimetric assays, viability for cells labeled with high effective specific activity {sup 99m}TcSAACQ-1 was 97{+-}4% at 2 h postlabeling and 85{+-}25% at 24 h postlabeling for incubation activities ranging from 245 to 8900 Bq/cell. DNA analysis showed that at these levels, there was no significant difference between the extent of DNA damage in the treated cells versus control cells. A series of preliminary SPECT/CT studies of transplants in mice were performed, which showed that the strategy is convenient and feasible and that it is possible to routinely assess procedures noninvasively and determine the number of cells transplanted.

  6. Naphthalene-based fluorescent probes for glutathione and their applications in living cells and patients with sepsis

    Science.gov (United States)

    Li, Jun; Kwon, Younghee; Chung, Kyung Soo; Lim, Chang Su; Lee, Dayoung; Yue, Yongkang; Yoon, Jisoo; Kim, Gyoungmi; Nam, Sang-Jip; Chung, Youn Wook; Kim, Hwan Myung; Yin, Caixia; Ryu, Ji-Hwan; Yoon, Juyoung

    2018-01-01

    Rationale: Among the biothiols-related diseases, sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection and can result in severe oxidative stress and damage to multiple organs. In this study, we aimed to develop a fluorescence chemosensor that can both detect GSH and further predict sepsis. Methods: In this study, two new naphthalene dialdehyde compounds containing different functional groups were synthesized, and the sensing abilities of these compounds towards biothiols and its applications for prediction of sepsis were investigated. Results: Our study revealed that the newly developed probe 6-methoxynaphthalene-2, 3-dicarbaldehyde (MNDA) has two-photon is capable of detecting GSH in live cells with two-photon microscopy (TPM) under the excitation at a wavelength of 900 nm. Furthermore, two GSH detection probes naphthalene-2,3-dicarboxaldehyde (NDA) and 6-fluoronaphthalene-2,3-dicarbaldehyde (FNDA) not only can detect GSH in living cells, but also showed clinical significance for the diagnosis and prediction of mortality in patients with sepsis. Conclusions: These results open up a promising direction for further medical diagnostic techniques. PMID:29507630

  7. Small molecule probes finely differentiate between various ds- and ss-DNA and RNA by fluorescence, CD and NMR response

    Energy Technology Data Exchange (ETDEWEB)

    Crnolatac, Ivo; Rogan, Iva; Majić, Boris; Tomić, Sanja [Division of Organic Chemistry and Biochemistry, Division of Physical Chemistry, Ruđer Bošković Institute, P.O. Box 180, 10002 Zagreb (Croatia); Deligeorgiev, Todor [Faculty of Chemistry and Pharmacy, University of Sofia (Bulgaria); Horvat, Gordan [Department of Physical Chemistry, Faculty of Science/Chemistry, Horvatovac 102A, HR-10000 Zagreb (Croatia); Makuc, Damjan; Plavec, Janez [Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, Ljubljana (Slovenia); EN-FIST Centre of Excellence, Trg Osvobodilne Fronte 13, Ljubljana (Slovenia); Pescitelli, Gennaro [Department of Chemistry, University of Pisa, Via Moruzzi 13, Pisa (Italy); Piantanida, Ivo, E-mail: pianta@irb.hr [Division of Organic Chemistry and Biochemistry, Division of Physical Chemistry, Ruđer Bošković Institute, P.O. Box 180, 10002 Zagreb (Croatia)

    2016-10-12

    Two small molecules showed intriguing properties of analytical multipurpose probes, whereby one chromophore gives different signal for many different DNA/RNA by application of several highly sensitive spectroscopic methods. Dyes revealed pronounced fluorescence ratiomeric differentiation between ds-AU-RNA, AT-DNA and GC-DNA in approximate order 10:8:1. Particularly interesting, dyes showed specific fluorimetric response for poly rA even at 10-fold excess of any other ss-RNA, and moreover such emission selectivity is preserved in multicomponent ss-RNA mixtures. The dyes also showed specific chiral recognition of poly rU in respect to the other ss-RNA by induced CD (ICD) pattern in visible range (400–500 nm), which was attributed to the dye-side-chain contribution to binding (confirmed by absence of any ICD band for reference compound lacking side-chain). Most intriguingly, minor difference in the side-chain attached to dye chromophore resulted in opposite sign of dye-ICD pattern, whereby differences in NMR NOESY contacts and proton chemical shifts between two dye/oligo rU complexes combined with MD simulations and CD calculations attributed observed bisignate ICD to the dimeric dye aggregate within oligo rU. - Highlights: • Novel dyes emit fluorescence only for poly rA even at high excess of all other ss-RNA. • Fluorescence response for AT-DNA is 8 times stronger than for GC-DNA. • Florescence induced by ds-RNA is 20% stronger that emission induced by ds-DNA. • Intrinsically non-chiral, dyes show strong and characteristic ICD response for poly rU.

  8. Zwitterionic Silane Copolymer for Ultra-Stable and Bright Biomolecular Probes Based on Fluorescent Quantum Dot Nanoclusters.

    Science.gov (United States)

    Dembele, Fatimata; Tasso, Mariana; Trapiella-Alfonso, Laura; Xu, Xiangzhen; Hanafi, Mohamed; Lequeux, Nicolas; Pons, Thomas

    2017-05-31

    Fluorescent semiconductor quantum dots (QDs) exhibit several unique properties that make them suitable candidates for biomolecular sensing, including high brightness, photostability, broad excitation, and narrow emission spectra. Assembling these QDs into robust and functionalizable nanosized clusters (QD-NSCs) can provide fluorescent probes that are several orders of magnitude brighter than individual QDs, thus allowing an even greater sensitivity of detection with simplified instrumentation. However, the formation of compact, antifouling, functionalizable, and stable QD-NSCs remains a challenging task, especially for a use at ultralow concentrations for single-molecule detection. Here, we describe the development of fluorescent QD-NSCs envisioned as a tool for fast and sensitive biomolecular recognition. First, QDs were assembled into very compact 100-150 nm diameter spherical aggregates; the final QD-NSCs were obtained by growing a cross-linked silica shell around these aggregates. Hydrolytic stability in several concentration and pH conditions is a key requirement for a potential and efficient single-molecule detection tool. However, the hydrolysis of Si-O-Si bonds leads to desorption of monosilane-based surface groups at very low silica concentrations or in a slightly basic medium. Thus, we designed a novel multidentate copolymer composed of multiple silane as well as zwitterionic monomers. Coating silica beads with this multidentate copolymer provided a robust surface chemistry that was demonstrated to be stable against hydrolysis, even at low concentrations. Copolymer-coated silica beads also showed low fouling properties and high colloidal stability in saline solutions. Furthermore, incorporation of additional azido-monomers enabled easy functionalization of QD-NSCs using copper-free bio-orthogonal cyclooctyne-azide click chemistry, as demonstrated by a biotin-streptavidin affinity test.

  9. Photostable bipolar fluorescent probe for video tracking plasma membranes related cellular processes.

    Science.gov (United States)

    Zhang, Xinfu; Wang, Chao; Jin, Liji; Han, Zhuo; Xiao, Yi

    2014-08-13

    Plasma membranes can sense the stimulations and transmit the signals from extracellular environment and then make further responses through changes in locations, shapes or morphologies. Common fluorescent membrane markers are not well suited for long time tracking due to their shorter retention time inside plasma membranes and/or their lower photostability. To this end, we develop a new bipolar marker, Mem-SQAC, which can stably insert into plasma membranes of different cells and exhibits a long retention time over 30 min. Mem-SQAC also inherits excellent photostability from the BODIPY dye family. Large two-photon absorption cross sections and long wavelength fluorescence emissions further enhance the competitiveness of Mem-SQAC as a membrane marker. By using Mem-SQAC, significant morphological changes of plasma membranes have been monitored during heavy metal poisoning and drug induced apoptosis of MCF-7 cells; the change tendencies are so distinctly different from each other that they can be used as indicators to distinguish different cell injuries. Further on, the complete processes of endocytosis toward Staphylococcus aureus and Escherichia coli by RAW 264.7 cells have been dynamically tracked. It is discovered that plasma membranes take quite different actions in response to the two bacteria, information unavailable in previous research reports.

  10. Probing the connection of PBSs to the photosystems in Spirulina platensis by artificially induced fluorescence fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Li Heng [Key Laboratory of Photochemistry, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Yang Shuzhen [Key Laboratory of Photochemistry, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Xie Jie [Key Laboratory of Photochemistry, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Zhao Jingquan [Key Laboratory of Photochemistry, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)]. E-mail: zhaojq@iccas.ac.cn

    2007-01-15

    The molecular architecture and the structural connections of phycobilisomes (PBSs) to the photosystems in the intact cells of Spirulina platensis were studied by taking advantage of glycerol- and betaine-induced fluorescence fluctuations. Generally, with a selective excitation of C-phycocyanin (C-PC), glycerol could induce not only decoupling of PBSs from the photosystems but also of C-PC rods from allophycocyanin (APC) cores, while betaine could strengthen the connection of PBSs to the thylakoid membrane but induce a partial dissociation of PBS. On the other hand, glycerol did not exert an influence on the fluorescence spectra of the photosystems in isolated thylakoid membrane. Therefore, it was deduced that glycerol could provide a molecular environment to weaken the hydrophobic interactions of not only the L{sub CM} with the membrane but also the linker polypeptides to the water-soluble phycobiliproteins (C-PC and APC), while the betaine could strengthen the hydrophobic interaction of L{sub CM} with the membrane but weaken the electrostatic interaction of linker polypeptides to C-PC and/or APC.

  11. Probing Energy and Electron Transfer Mechanisms in Fluorescence Quenching of Biomass Carbon Quantum Dots.

    Science.gov (United States)

    Liang, Zicheng; Kang, Mijeong; Payne, Gregory F; Wang, Xiaohui; Sun, Runcang

    2016-07-13

    The recent discovery of biomass-derived carbon quantum dots (CQDs) offers the potential to extend the sensing and imaging capabilities of quantum dots (QDs) to applications that require biocompatibility and environmental friendliness. Many studies have confirmed the exciting optical properties of CQDs and suggested a range of applications, but realizing the potential of CQDs will require a deeper fundamental understanding of their photophysical behavior. Here, biomass-derived CQDs were synthesized by hydrothermal processing methods from the aminopolysaccharide chitosan, and their fluorescence quenching behaviors were investigated. A family of nitroaromatics with different ring substituents was used to generate systematically varying CQD-quenching behaviors. Experimental evidence including a correlation between quenching constant and spectral overlap, fluorescence lifetime decay, and donor-acceptor distance all demonstrate that the primary mechanism for QCD-quenching is Förster resonance energy transfer (FRET) and not electron transfer. Spectroelectrochemical studies with redox-dependent quenching molecules and studies with complex dye molecules further support this conclusion. We envision this fundamental understanding of CQDs will facilitate the application of these emerging nanomaterials for sensing and imaging.

  12. Evaluation of a fluorescent polarization immunoassay for whole blood everolimus determination using samples from renal transplant recipients.

    Science.gov (United States)

    Salm, Paul; Warnholtz, Christopher; Boyd, Jared; Arabshahi, Lili; Marbach, Peter; Taylor, Paul J

    2006-07-01

    This study compared the performance of a fluorescent polarization immunoassay (FPIA) against HPLC-tandem mass spectrometry (HPLC-MS) for the measurement of everolimus in renal transplant recipients. A total of 333 pre-dose samples from 45 renal transplant patients were analyzed by FPIA and HPLC-MS. The inter-batch inaccuracy and precision of the FPIA for control samples were equation FPIA = 1.19 x HPLC-MS + 0.51. The mean bias was 24.4% (95% CI: -3.0 to 54.2%, range: -30.1% to 79.4%). The FPIA had acceptable analytical performance during the study but compared to HPLC-MS overestimated everolimus in patient samples. This overestimation is probably due to calibration differences between the methods and cross-reactivity of the FPIA antibody with everolimus metabolites. The clinical importance of the observed overestimation by FPIA requires further investigation.

  13. ICT-Isomerization-Induced Turn-On Fluorescence Probe with a Large Emission Shift for Mercury Ion: Application in Combinational Molecular Logic.

    Science.gov (United States)

    Bhatta, Sushil Ranjan; Mondal, Bijan; Vijaykumar, Gonela; Thakur, Arunabha

    2017-10-02

    A unique turn-on fluorescent device based on a ferrocene-aminonaphtholate derivative specific for Hg 2+ cation was developed. Upon binding with Hg 2+ ion, the probe shows a dramatic fluorescence enhancement (the fluorescence quantum yield increases 58-fold) along with a large red shift of 68 nm in the emission spectrum. The fluorescence enhancement with a red shift may be ascribed to the combinational effect of C═N isomerization and an extended intramolecular charge transfer (ICT) mechanism. The response was instantaneous with a detection limit of 2.7 × 10 -9 M. Upon Hg 2+ recognition, the ferrocene/ferrocenium redox peak was anodically shifted by ΔE 1/2 = 72 mV along with a "naked eye" color change from faint yellow to pale orange for this metal cation. Further, upon protonation of the imine nitrogen, the present probe displays a high fluorescence output due to suppression of the C═N isomerization process. Upon deprotonation using strong base, the fluorescence steadily decreases, which indicates that H + and OH - can be used to regulate the off-on-off fluorescence switching of the present probe. Density functional theory studies revealed that the addition of acid leads to protonation of the imine N (according to natural bond orbital analysis), and the resulting iminium proton forms a strong H-bond (2.307 Å) with one of the triazole N atoms to form a five-membered ring, which makes the molecule rigid; hence, enhancement of the ICT process takes place, thereby leading to a fluorescence enhancement with a red shift. The unprecedented combination of H + , OH - , and Hg 2+ ions has been used to generate a molecular system exhibiting the INHIBIT-OR combinational logic operation.

  14. Dual lanthanide-doped complexes: the development of a time-resolved ratiometric fluorescent probe for anthrax biomarker and a paper-based visual sensor.

    Science.gov (United States)

    Wang, Qi-Xian; Xue, Shi-Fan; Chen, Zi-Han; Ma, Shi-Hui; Zhang, Shengqiang; Shi, Guoyue; Zhang, Min

    2017-08-15

    In this work, a novel time-resolved ratiometric fluorescent probe based on dual lanthanide (Tb: terbium, and Eu: europium)-doped complexes (Tb/DPA@SiO 2 -Eu/GMP) has been designed for detecting anthrax biomarker (dipicolinic acid, DPA), a unique and major component of anthrax spores. In such complexes-based probe, Tb/DPA@SiO 2 can serve as a stable reference signal with green fluorescence and Eu/GMP act as a sensitive response signal with red fluorescence for ratiometric fluorescent sensing DPA. Additionally, the probe exhibits long fluorescence lifetime, which can significantly reduce the autofluorescence interferences from biological samples by using time-resolved fluorescence measurement. More significantly, a paper-based visual sensor for DPA has been devised by using filter paper embedded with Tb/DPA@SiO 2 -Eu/GMP, and we have proved its utility for fluorescent detection of DPA, in which only a handheld UV lamp is used. In the presence of DPA, the paper-based visual sensor, illuminated by a handheld UV lamp, would result in an obvious fluorescence color change from green to red, which can be easily observed with naked eyes. The paper-based visual sensor is stable, portable, disposable, cost-effective and easy-to-use. The feasibility of using a smartphone with easy-to-access color-scanning APP as the detection platform for quantitative scanometric assays has been also demonstrated by coupled with our proposed paper-based visual sensor. This work unveils an effective method for accurate, sensitive and selective monitoring anthrax biomarker with backgroud-free and self-calibrating properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. A Novel “Off-On” Fluorescent Probe Based on Carbon Nitride Nanoribbons for the Detection of Citrate Anion and Live Cell Imaging

    Directory of Open Access Journals (Sweden)

    Yanling Hu

    2018-04-01

    Full Text Available A novel fluorescent “off-on” probe based on carbon nitride (C3N4 nanoribbons was developed for citrate anion (C6H5O73− detection. The fluorescence of C3N4 nanoribbons can be quenched by Cu2+ and then recovered by the addition of C6H5O73−, because the chelation between C6H5O73− and Cu2+ blocks the electron transfer between Cu2+ and C3N4 nanoribbons. The turn-on fluorescent sensor using this fluorescent “off-on” probe can detect C6H5O73− rapidly and selectively, showing a wide detection linear range (1~400 μM and a low detection limit (0.78 μM in aqueous solutions. Importantly, this C3N4 nanoribbon-based “off-on” probe exhibits good biocompatibility and can be used as fluorescent visualizer for exogenous C6H5O73− in HeLa cells.

  16. Use of fluorescent probes to follow membrane traffic in nerve terminals

    Directory of Open Access Journals (Sweden)

    Guatimosim C.

    1998-01-01

    Full Text Available Optical tracers in conjunction with fluorescence microscopy have become widely used to follow the movement of synaptic vesicles in nerve terminals. The present review discusses the use of these optical methods to understand the regulation of exocytosis and endocytosis of synaptic vesicles. The maintenance of neurotransmission depends on the constant recycling of synaptic vesicles and important insights have been gained by visualization of vesicles with the vital dye FM1-43. A number of questions related to the control of recycling of synaptic vesicles by prolonged stimulation and the role of calcium to control membrane internalization are now being addressed. It is expected that optical monitoring of presynaptic activity coupled to appropriate genetic models will contribute to the understanding of membrane traffic in synaptic terminals.

  17. Optical Antenna-Based Fluorescence Correlation Spectroscopy to Probe the Nanoscale Dynamics of Biological Membranes.

    Science.gov (United States)

    Winkler, Pamina M; Regmi, Raju; Flauraud, Valentin; Brugger, Jürgen; Rigneault, Hervé; Wenger, Jérôme; García-Parajo, María F

    2018-01-04

    The plasma membrane of living cells is compartmentalized at multiple spatial scales ranging from the nano- to the mesoscale. This nonrandom organization is crucial for a large number of cellular functions. At the nanoscale, cell membranes organize into dynamic nanoassemblies enriched by cholesterol, sphingolipids, and certain types of proteins. Investigating these nanoassemblies known as lipid rafts is of paramount interest in fundamental cell biology. However, this goal requires simultaneous nanometer spatial precision and microsecond temporal resolution, which is beyond the reach of common microscopes. Optical antennas based on metallic nanostructures efficiently enhance and confine light into nanometer dimensions, breaching the diffraction limit of light. In this Perspective, we discuss recent progress combining optical antennas with fluorescence correlation spectroscopy (FCS) to monitor microsecond dynamics at nanoscale spatial dimensions. These new developments offer numerous opportunities to investigate lipid and protein dynamics in both mimetic and native biological membranes.

  18. Alkylation of Staurosporine to Derive a Kinase Probe for Fluorescence Applications.

    Science.gov (United States)

    Disney, Alexander J M; Kellam, Barrie; Dekker, Lodewijk V

    2016-05-06

    The natural product staurosporine is a high-affinity inhibitor of nearly all mammalian protein kinases. The labelling of staurosporine has proven effective as a means of generating protein kinase research tools. Most tools have been generated by acylation of the 4'-methylamine of the sugar moiety of staurosporine. Herein we describe the alkylation of this group as a first step to generate a fluorescently labelled staurosporine. Following alkylation, a polyethylene glycol linker was installed, allowing subsequent attachment of fluorescein. We report that this fluorescein-staurosporine conjugate binds to cAMP-dependent protein kinase in the nanomolar range. Furthermore, its binding can be antagonised with unmodified staurosporine as well as ATP, indicating it targets the ATP binding site in a similar fashion to native staurosporine. This reagent has potential application as a screening tool for protein kinases of interest. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  19. Solvatochromic fluorene-linked nucleoside and DNA as color-changing fluorescent probes for sensing interactions

    Czech Academy of Sciences Publication Activity Database

    Dziuba, Dmytro; Pospíšil, Petr; Matyašovský, Ján; Brynda, Jiří; Nachtigallová, Dana; Rulíšek, Lubomír; Pohl, Radek; Hof, Martin; Hocek, Michal

    2016-01-01

    Roč. 7, č. 9 (2016), s. 5775-5785 ISSN 2041-6520 R&D Projects: GA ČR GBP206/12/G151; GA ČR(CZ) GC14-03141J; GA ČR(CZ) GA14-31419S; GA MŠk(CZ) LO1304 EU Projects: European Commission(XE) 642023 - ClickGene Institutional support: RVO:61388963 ; RVO:61388955 Keywords : environmentally sensitive fluorescent * molecular dynamics simulations * oligonucleotides Subject RIV: CC - Organic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 8.668, year: 2016 http://pubs.rsc.org/en/content/articlepdf/2016/sc/c6sc02548j

  20. Bacterial Phytochromes, Cyanobacteriochromes and Allophycocyanins as a Source of Near-Infrared Fluorescent Probes

    Directory of Open Access Journals (Sweden)

    Olena S. Oliinyk

    2017-08-01

    Full Text Available Bacterial photoreceptors absorb light energy and transform it into intracellular signals that regulate metabolism. Bacterial phytochrome photoreceptors (BphPs, some cyanobacteriochromes (CBCRs and allophycocyanins (APCs possess the near-infrared (NIR absorbance spectra that make them promising molecular templates to design NIR fluorescent proteins (FPs and biosensors for studies in mammalian cells and whole animals. Here, we review structures, photochemical properties and molecular functions of several families of bacterial photoreceptors. We next analyze molecular evolution approaches to develop NIR FPs and biosensors. We then discuss phenotypes of current BphP-based NIR FPs and compare them with FPs derived from CBCRs and APCs. Lastly, we overview imaging applications of NIR FPs in live cells and in vivo. Our review provides guidelines for selection of existing NIR FPs, as well as engineering approaches to develop NIR FPs from the novel natural templates such as CBCRs.

  1. In Vivo Tumor Angiogenesis Imaging Using Peptide-Based Near-Infrared Fluorescent Probes.

    Science.gov (United States)

    Huang, Rui; Conti, Peter S; Chen, Kai

    2016-01-01

    Near-infrared fluorescence (NIRF) imaging is an emerging imaging technique for studying diseases at the molecular level. Optical imaging with a near-infrared emitting fluorophore for targeting tumor angiogenesis offers a noninvasive method for early tumor detection and efficient monitoring of tumor response to anti-angiogenesis therapy. CD13 receptor, a zinc-dependent membrane-bound ectopeptidase, plays important roles in regulating tumor angiogenesis and the growth of new blood vessels. In this chapter, we use CD13 receptor as an example to demonstrate how to construct CD13-specific NGR-containing peptides via bioorthogonal click chemistry for visualizing and quantifying the CD13 receptor expression in vivo by means of NIRF optical imaging.

  2. Comparison of capillary electrophoresis-based immunoassay with fluorescence polarization immunoassay for the immunodetermination of methamphetamine using various methamphetamine antibodies.

    Science.gov (United States)

    Choi, J; Kim, C; Choi, M J

    1998-11-01

    An accurate and simple immunoassay using capillary electrophoresis (CE) with laser-induced fluorescence (LIF) was performed for the detection of methamphetamine (MA) in urine. The CE-LIF was conducted with an untreated fused-silica column using antiserum and a tracer of fluorescein isothiocyanate (FITC)-labeled MA. This CE-LIF system was compared with fluorescence polarization immunoassay (FPIA) in a TDx analyzer in the photo-check mode using the same FITC-labeled tracer and the same antiserum. Various antibodies, not only those prepared by our own immunogens but also those from commercial sources, were screened and characterized in both assay systems with regard to sensitivity, precision, and cross-reactivity. Both systems satisfied analytical precision and gave similar cross-reactivity patterns. However, the CE-LIF-based immunoassay was approximately one order superior to FPIA in sensitivity, requiring less volume of sample, antiserum, and tracer for the assay. Considering that the FPIA system is well known to be a useful tool for screening antibodies and detecting drugs, the CE-LIF-based immunoassay system, which is seemingly more advantageous than the FPIA system, appears to have great power for the characterization of antibodies and for the detection of MA in urine.

  3. Growth, polarized Raman and fluorescence properties of TbCa4O(BO3)3 single crystal

    Science.gov (United States)

    Yuan, Dongsheng; Gao, Zeliang; Jia, Zhitai; Shu, Jun; Li, Yang; Tao, Xutang

    2015-04-01

    A single crystal of TbCa4O(BO3)3 (TbCOB) with diameter of 35 mm and length of 80 mm has been successfully grown using the Czochralski (Cz) method. The polarized Raman spectra were studied to analyze the vibrational structure of TbCOB, especially the modes from [BO3]3- triangles that are responsible for the nonlinear optical generation. The fluorescence properties of the X-cut, Y-cut, and Z-cut non-centrosymmetric TbCOB crystals were measured for the first time, and both f-d and f-f transitions were identified according to the energy level diagram. Based on the non-radiative energy transfer process, TbCOB crystal shows the characteristic emission of Tb3+ corresponding to 5D4 → 7F6,5,4,3 transitions with the green light of 542 nm (5D4 → 7F5) being the most prominent group. Additionally, the lifetime decay indicates single exponential character for the excited wavelength at 378 nm, following the result of τ = 2.07 ms at room temperature. The long fluorescence lifetime and good spectra properties of TbCOB single crystal indicate its potential optical prospects.

  4. Enzymatic studies on planar supported membranes using a widefield fluorescence LAURDAN Generalized Polarization imaging approach

    DEFF Research Database (Denmark)

    Brewer, Jonathan R.; Thoke, Henrik Seir; Stock, Robeto

    2017-01-01

    the temporal resolution previously achieved using laser scanning based microscopes. A dedicated protocol to calibrate LAURDAN GP data obtained with charge-coupled device (CCD) cameras as detectors is also presented, enabling reliable assignment of GP values in the field of view. Using this methodology we...... to a single solid ordered phase at longer time scales. Additionally, we comparatively studied this system using the membrane fluorophore DiIC18. The advantages and limitations of both fluorescent dyes are discussed, emphasizing the adequacy of LAURDAN GP imaging to explore this type of membrane phenomena....

  5. Use of selenium to detect mercury in water and cells: an enhancement of the sensitivity and specificity of a seleno fluorescent probe.

    Science.gov (United States)

    Tang, Bo; Ding, Baiyu; Xu, Kehua; Tong, Lili

    2009-01-01

    Seleno fluorescent probe: An organoselenium fluorescent probe (FSe-1) for mercury was designed based on the irreversible deselenation mechanism. FSe-1 exhibits an ultrahigh selectivity and sensitivity for Hg(2+) detection only for reactive selenium atom sites, due the strong affinity between Se and Hg. Furthermore, the new probe has been successfully used for imaging mercury ions in RAW 264.7 cells (a mouse macrophage cell line; see figure).Inspired by the antitoxic function of selenium towards heavy-metal ions, we designed an organoselenium fluorescent probe (FSe-1) for mercury. The reaction of FSe-1 and Hg(2+) is an irreversible deselenation mechanism based on the selenophilic character of mercury. FSe-1 exhibits an ultrahigh selectivity and sensitivity for Hg(2+) detection only for reactive selenium atom sites due to the strong affinity between Se and Hg. The experimental results proved that FSe-1 was selective for Hg(2+) ions over other relevant metal ions and bioanalytes, and also showed an enhancement in sensitivity of up to 1.0 nM, which is lower than the current Environmental Protection Agency standard for drinking water. Furthermore, the new probe has been successfully applied to the imaging of mercury ions in RAW 264.7 cells (a mouse macrophage cell line) with high sensitivity and selectivity.

  6. A two-photon fluorescent turn-on probe for imaging of SO{sub 2} derivatives in living cells and tissues

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaoyan; Zhu, Longming; Liu, Hong-wen; Hu, Xiaoxiao; Peng, Rui-zi; Zhang, Jing; Zhang, Xiao-Bing, E-mail: xbzhang@hnu.edu.cn; Tan, Weihong, E-mail: tan@chem.ufl.edu

    2016-09-21

    SO{sub 2} and its derivatives (bisulfite/sulfite) play crucial roles in several physiological processes. Therefore, development of reliable analytical methods for monitoring SO{sub 2} and its derivatives in biological systems is very significant. In this paper, a FRET-based two-photon fluorescent turn-on probe, A-HCy, was proposed for specific detection of SO{sub 2} derivatives through the bisulfite/sulfite-promoted Michael addition reaction. In this FRET system, an acedan (2-acetyl-6-dialkylaminonaphthalene) moiety was selected as a two-photon donor and a hemicyanine derivative served as both the quencher and the recognition unit for bisulfite/sulfite. A-HCy exhibited excellent selectivity and rapid response to HSO{sub 3}{sup −} with a detection limit of 0.24 μM. More importantly, probe A-HCy was first successfully applied in two-photon fluorescence imaging of biological SO{sub 2} derivatives in living cells and tissues, suggesting its great potential for practical application in biological systems. - Highlights: • A FRET-based two-photon fluorescent probe for detecting SO{sub 2} derivatives was proposed. • The probe shows high sensitivity, excellent selectivity, rapid response as well as low cytotoxicity. • The probe was capable of detecting SO{sub 2} derivatives up to 170 μm depth in tissues.

  7. Plane polarized x-ray fluorescence system for the in vivo measurement of platinum in head and neck tumours

    Science.gov (United States)

    Ali, P. A.; Al-Hussany, A. F.; Bennett, C. A.; Hancock, D. A.; El-Sharkawi, A. M.

    1998-08-01

    A plane polarized x-ray fluorescence system based on an orthovoltage radiotherapy treatment unit, the Pantak DXT-300, has been developed and optimized to measure tumour platinum concentration. The platinum derives from platinum based chemotherapy agents, such as cisplatin and carboplatin used to treat tumours in the head and neck region. Photons from an x-ray tube are polarized by scattering through , and used to stimulate the emission of characteristic platinum x-rays from the tumour. Information about the drug in the tumour could be of use in establishing dose-response relationships, in order to optimize the treatment and reduce the toxicity of the drug. The performance of the system was optimized with respect to the applied x-ray tube voltage, the current and the filter material; the effect on the minimum detection limit (MDL) of the thickness of the overlying tissue surrounding the tumour was investigated in detail. The lowest MDL is achieved using 0.25 mm of tin filter and x-ray tube voltage of 220 kV. This is 5.6 ppm for a tumour surrounded with 20 mm of overlying tissue, a measurement time of 2000 s and an estimated skin dose of 3.0 mGy. This represents the most sensitive in vivo XRF system to date. We have embarked on a clinical pilot study to measure the platinum concentration in tumours of the head and neck, and expect initial results to be available in the near future.

  8. Specificity fingerprinting of retaining beta-1,4-glycanases in the Cellulomonas fimi secretome using two fluorescent mechanism-based probes.

    Science.gov (United States)

    Hekmat, Omid; Florizone, Christine; Kim, Young-Wan; Eltis, Lindsay D; Warren, R Antony J; Withers, Stephen G

    2007-11-23

    Functional proteomics methods are crucial for activity- and mechanism-based investigation of enzymes in biological systems at a post-translational stage. Glycosidases have central roles in cellular metabolism and its regulation, and their dysfunction can have detrimental effects. These enzymes also play key roles in biomass conversion. A functional profiling methodology was developed for direct, fluorescence-based, in-gel analysis of retaining beta-glycosidases. Two spectrally nonoverlapping fluorescent, mechanism-based probes containing different recognition elements for retaining cellulases and xylanases were prepared. The specificity-based covalent labelling of retaining glycanases by the two probes was demonstrated in model enzyme mixtures. Using the two probes and mass spectrometry, the secretomes of the biomass-converting bacterium Cellulomonas fimi, under induction by different polyglycan growth substrates, were analysed to obtain a specificity profile of the C. fimi retaining beta-glycanases. This is a facile strategy for the analysis of glycosidases produced by biomass-degrading organisms.

  9. Spin-polarized scanning tunneling microscopy with quantitative insights into magnetic probes.

    Science.gov (United States)

    Phark, Soo-Hyon; Sander, Dirk

    2017-01-01

    Spin-polarized scanning tunneling microscopy and spectroscopy (spin-STM/S) have been successfully applied to magnetic characterizations of individual nanostructures. Spin-STM/S is often performed in magnetic fields of up to some Tesla, which may strongly influence the tip state. In spite of the pivotal role of the tip in spin-STM/S, the contribution of the tip to the differential conductance d I /d V signal in an external field has rarely been investigated in detail. In this review, an advanced analysis of spin-STM/S data measured on magnetic nanoislands, which relies on a quantitative magnetic characterization of tips, is discussed. Taking advantage of the uniaxial out-of-plane magnetic anisotropy of Co bilayer nanoisland on Cu(111), in-field spin-STM on this system has enabled a quantitative determination, and thereby, a categorization of the magnetic states of the tips. The resulting in-depth and conclusive analysis of magnetic characterization of the tip opens new venues for a clear-cut sub-nanometer scale spin ordering and spin-dependent electronic structure of the non-collinear magnetic state in bilayer high Fe nanoislands on Cu(111).

  10. Low moment ferrimagnetism in Mn3Al as probed by Polarized Neutron Reflectometry

    Science.gov (United States)

    Jamer, Michelle; Wang, Yung-Jui; Borchers, Julie; Kirby, Brian; Barbiellini, Bernardo; Bansil, Arun; Heiman, Don

    For future spintronic devices, it is paramount to limit stray magnetic interactions which can negatively impact spin injection. A new class of materials called half-metallic antiferromagnets or compensated ferrimagnets have been proposed to remedy this problem. In this work, Mn3Al thin films have shown promising room temperature low-moment ferrimagnetic magnetic properties. Epitaxial Mn3Al thin films (50 nm) were grown on desorbed GaAs(001) substrates via MBE at 200 °C and annealed further to temperatures between 250 - 350 °C. The D03 Heusler-type phase was determined by X-ray diffraction with texturing in the [311] direction. Density functional theory, performed using VASP, indicated that the crystallographic structure of Mn3Al is able to form energetically with a low magnetic moment (0.017 μB/f.u.) despite some epitaxial distortion. SQUID magnetometry confirmed the low magnetic moment and high Curie temperature (610 K) of the structure. Polarized Neutron Reflectometry was used to determine the effect of epitaxy on the magnetic moment of Mn3Al, and analysis confirms a low magnetic moment (0.11 μB/f.u.) for the samples annealed at temperatures between 200-300 °C. This analysis further suggests that the relaxation of the Mn3Al at the interface. National Science Foundation ECCS-1402738.

  11. A potential fluorescent probe: Maillard reaction product from glutathione and ascorbic acid for rapid and label-free dual detection of Hg(2+) and biothiols.

    Science.gov (United States)

    Dong, Jiang Xue; Song, Xiao Fang; Shi, Yan; Gao, Zhong Feng; Li, Bang Lin; Li, Nian Bing; Luo, Hong Qun

    2016-07-15

    Maillard reactions and their fluorescent products have drawn much attention in the fields of food and life science, however, the application of fluorescent products separated from the reaction as an indicator for detection of certain substances in sensor field has not been mentioned. In this article, we report on an easy-to-synthesize and water-soluble fluorescent probe separated from the typical Maillard reaction products of glutathione and ascorbic acid, with excellent stability and high quantum yield (18.2%). The further application of the probe has been explored for dual detection of Hg(2+) and biothiols including cysteine, homocysteine, and glutathione, which is based on Hg(2+)-induced fluorescence quenching of the Maillard reaction fluorescent products (MRFPs) and the fluorescence recovery as the introduction of biothiols. This sensing system exhibits a good selectivity and sensitivity, and the linear ranges for Hg(2+), cysteine, homocysteine, and glutathione are 0.05-12, 0.5-10, 0.3-20, and 0.3-20μM, respectively. The detection limits for Hg(2+), cysteine, homocysteine, and glutathione are 22, 47, 96, and 30nM at a signal-to-noise ratio of 3, respectively. Furthermore, the practical applications of this sensor for Hg(2+) and biothiols determination in water samples and human plasma sample have been demonstrated with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Molecularly Imprinted Core-Shell CdSe@SiO2/CDs as a Ratiometric Fluorescent Probe for 4-Nitrophenol Sensing

    Science.gov (United States)

    Liu, Mingyue; Gao, Zhao; Yu, Yanjun; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

    2018-01-01

    4-Nitrophenol (4-NP) is a priority pollutant in water and is both carcinogenic and genotoxic to humans and wildlife even at very low concentrations. Thus, we herein fabricated a novel molecularly imprinted core-shell nanohybrid as a ratiometric fluorescent sensor for the highly sensitive and selective detection of 4-NP. This sensor was functioned by the transfer of fluorescence resonance energy between photoluminescent carbon dots (CDs) and 4-NP. This sensor was synthesized by linking organosilane-functionalized CDs to silica-coated CdSe quantum dots (CdSe@SiO2) via Si-O bonds. The nanohybrids were further modified by anchoring a molecularly imprinted polymer (MIP) layer on the ratiometric fluorescent sensor through a facile sol-gel polymerization method. The morphology, chemical structure, and optical properties of the resulting molecularly imprinted dual-emission fluorescent probe were characterized by transmission electron microscopy and spectroscopic analysis. The probe was then applied in the detection of 4-NP and exhibited good linearity between 0.051 and 13.7 μg/mL, in addition to a low detection limit of 0.026 μg/mL. Furthermore, the simplicity, reliability, high selectivity, and high sensitivity of the developed sensor demonstrate that the combination of MIPs and ratiometric fluorescence allows the preparation of excellent fluorescent sensors for the detection of trace or ultra-trace analytes.

  13. Detection of Myocardial Ischemia-Reperfusion Injury Using a Fluorescent Near-Infrared Zinc(II-Dipicolylamine Probe and 99mTc Glucarate

    Directory of Open Access Journals (Sweden)

    Leonie wyffels

    2012-05-01

    Full Text Available A fluorescent zinc 2,2′-dipicolylamine coordination complex PSVue®794 (probe 1 is known to selectively bind to phosphatidylserine exposed on the surface of apoptotic and necrotic cells. In this study, we investigated the cell death targeting properties of probe 1 in myocardial ischemia-reperfusion injury. A rat heart model of ischemia-reperfusion was used. Probe 1, control dye, or 99mTc glucarate was intravenously injected in rats subjected to 30-minute and 5-minute myocardial ischemia followed by 2-hour reperfusion. At 90 minutes or 20 hours postinjection, myocardial uptake was evaluated ex vivo by fluorescence imaging and autoradiography. Hematoxylin-eosin and cleaved caspase-3 staining was performed on myocardial sections to demonstrate the presence of ischemia-reperfusion injury and apoptosis. Selective accumulation of probe 1 could be detected in the area at risk up to 20 hours postinjection. Similar topography and extent of uptake of probe 1 and 99mTc glucarate were observed at 90 minutes postinjection. Histologic analysis demonstrated the presence of necrosis, but only a few apoptotic cells could be detected. Probe 1 selectively accumulates in myocardial ischemia-reperfusion injury and is a promising cell death imaging tool.

  14. Orientation of cutinase adsorbed onto PMMA nanoparticles probed by tryptophan fluorescence.

    Science.g