Sample records for simple fluorescence based

  1. Medically relevant assays with a simple smartphone and tablet based fluorescence detection system.

    PubMed

    Wargocki, Piotr; Deng, Wei; Anwer, Ayad G; Goldys, Ewa M

    2015-01-01

    Cell phones and smart phones can be reconfigured as biomedical sensor devices but this requires specialized add-ons. In this paper we present a simple cell phone-based portable bioassay platform, which can be used with fluorescent assays in solution. The system consists of a tablet, a polarizer, a smart phone (camera) and a box that provides dark readout conditions. The assay in a well plate is placed on the tablet screen acting as an excitation source. A polarizer on top of the well plate separates excitation light from assay fluorescence emission enabling assay readout with a smartphone camera. The assay result is obtained by analysing the intensity of image pixels in an appropriate colour channel. With this device we carried out two assays, for collagenase and trypsin using fluorescein as the detected fluorophore. The results of collagenase assay with the lowest measured concentration of 3.75 µg/mL and 0.938 µg in total in the sample were comparable to those obtained by a microplate reader. The lowest measured amount of trypsin was 930 pg, which is comparable to the low detection limit of 400 pg for this assay obtained in a microplate reader. The device is sensitive enough to be used in point-of-care medical diagnostics of clinically relevant conditions, including arthritis, cystic fibrosis and acute pancreatitis. PMID:26007723

  2. Medically Relevant Assays with a Simple Smartphone and Tablet Based Fluorescence Detection System

    PubMed Central

    Wargocki, Piotr; Deng, Wei; Anwer, Ayad G.; Goldys, Ewa M.

    2015-01-01

    Cell phones and smart phones can be reconfigured as biomedical sensor devices but this requires specialized add-ons. In this paper we present a simple cell phone-based portable bioassay platform, which can be used with fluorescent assays in solution. The system consists of a tablet, a polarizer, a smart phone (camera) and a box that provides dark readout conditions. The assay in a well plate is placed on the tablet screen acting as an excitation source. A polarizer on top of the well plate separates excitation light from assay fluorescence emission enabling assay readout with a smartphone camera. The assay result is obtained by analysing the intensity of image pixels in an appropriate colour channel. With this device we carried out two assays, for collagenase and trypsin using fluorescein as the detected fluorophore. The results of collagenase assay with the lowest measured concentration of 3.75 µg/mL and 0.938 µg in total in the sample were comparable to those obtained by a microplate reader. The lowest measured amount of trypsin was 930 pg, which is comparable to the low detection limit of 400 pg for this assay obtained in a microplate reader. The device is sensitive enough to be used in point-of-care medical diagnostics of clinically relevant conditions, including arthritis, cystic fibrosis and acute pancreatitis. PMID:26007723

  3. A simple and sensitive label-free fluorescent approach for protein detection based on a Perylene probe and aptamer.

    PubMed

    Lv, Zhenzhen; Liu, Jinchuan; Bai, Wenhui; Yang, Shuming; Chen, Ailiang

    2015-02-15

    Highly sensitive detection of proteins is of great importance for effective clinical diagnosis and biomedical research. However, so far most detection methods rely on antibody-based immunoassays and are usually laborious and time-consuming with poor sensitivity. Here, we developed a simple and ultra-sensitive method to detect a biomarker protein-thrombin by taking advantage of the fluorescent probe Perylene tetracarboxylic acid diimide (PTCDI) derivatives and thrombin aptamer. The water-soluble dye PTCDI shows strong fluorescence in buffer solution for the existence of free dye monomer, but becomes weak after aggregation through self-assembly on nucleic acid aptamer. In the presence of thrombin, it specifically binds to thrombin aptamer which causes the conformational transition between aptamer and PTCDI and results in a significant fluorescence recovery. The results showed that as low as 40 pM of thrombin could be detected by this method. The high sensitivity of the developed sensing system mainly attributes to the ultra-sensitivity of the fluorescence intensity changes of PTCDI. With the specificity of aptamer, the assay exhibited high selectivity for thrombin against three other proteins (bovine serum albumin, lysozyme, mouse IgG) and 1% diluted fetal bovine serum. The detection method might be extended to sensitive detection of a variety of proteins for its advantages of isothermal conditions required, simple and rapid without multiple separation and washing steps. PMID:25310484

  4. A simple and sensitive fluorescent sensor for methyl parathion based on L-tyrosine methyl ester functionalized carbon dots.

    PubMed

    Hou, Juying; Dong, Jing; Zhu, Haishuang; Teng, Xue; Ai, Shiyun; Mang, Minglin

    2015-06-15

    In this paper, a simple and sensitive fluorescent sensor for methyl parathion is developed based on L-tyrosine methyl ester functionalized carbon dots (Tyr-CDs) and tyrosinase system. The carbon dots are obtained by simple hydrothermal reaction using citric acid as carbon resource and L-tyrosine methyl ester as modification reagent. The carbon dots are characterized by transmission electron microscope, high resolution transmission electron microscopy, X-ray diffraction spectrum, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The carbon dots show strong and stable photoluminescence with a quantum yield of 3.8%. Tyrosinase can catalyze the oxidation of tyrosine methyl ester on the surface of carbon dots to corresponding quinone products, which can quench the fluorescence of carbon dots. When organophosphorus pesticides (OPs) are introduced in system, they can decrease the enzyme activity, thus decrease the fluorescence quenching rate. Methyl parathion, as a model of OPs, was detected. Experimental results show that the enzyme inhibition rate is proportional to the logarithm of the methyl parathion concentration in the range 1.0×10(-10)-1.0×10(-4) M with the detection limit (S/N=3) of 4.8×10(-11) M. This determination method shows a low detection limit, wide linear range, good selectivity and high reproducibility. This sensing system has been successfully used for the analysis of cabbage, milk and fruit juice samples. PMID:25558870

  5. Dual-channel detection of Cu(2+) and F(-) with a simple Schiff-based colorimetric and fluorescent sensor.

    PubMed

    Na, Yu Jeong; Choi, Ye Won; Yun, Jin Yeong; Park, Kyung-Min; Chang, Pahn-Shick; Kim, Cheal

    2014-10-24

    A simple and easily synthesized colorimetric and fluorescent receptor 1, based on 4-diethylaminosalicylaldehyde moieties as a binding and signaling unit, has been synthesized and characterized. The receptor 1 has a selective colorimetric sensing ability for copper (II) ion by changing color from colorless to yellow in aqueous solution, and could be utilized to monitor Cu(II) over a wide pH range of 4-11. In addition, the detection limit (12?M) of 1 for Cu(2+) is much lower than that (30?M) recommended by WHO in drinking water, and its copper complex could be reversible simply through treatment with a proper reagent such as EDTA. Moreover, receptor 1 exhibited both a color change from colorless to yellow and fluorescence enhancement with a red shift upon addition to F(-) in DMSO. The recognition mechanism was attributed to the intermolecular proton transfer between the hydroxyl group of the receptor and the fluoride. PMID:25459728

  6. A simple and sensitive surface molecularly imprinted polymers based fluorescence sensor for detection of ?-Cyhalothrin.

    PubMed

    Liu, Chunbo; Song, Zhilong; Pan, Jianming; Yan, Yongsheng; Cao, Zhijing; Wei, Xiao; Gao, Lin; Wang, Juan; Dai, Jiangdong; Meng, Minjia; Yu, Ping

    2014-07-01

    In this study, surface molecularly imprinted YVO4:Eu(3+) nanoparticles with molecular recognitive optosensing activity were successfully prepared by precipitation polymerization using ?-Cyhalothrin (LC) as template molecules, methacrylic acid and ethylene glycol dimethacrylate as the polymerization precursors which could complex with template molecules, and the material has been characterized by SEM, TEM, FT-IR, XRD, TGA and so on. Meanwhile, the as-prepared core-shell structured nanocomposite (YVO4:Eu(3+)@MIPs), which was composed of lanthanide doped YVO4:Eu(3+) as fluorescent signal and surface molecular imprinted polymers as molecular selective recognition sites, could selectively and sensitively optosense the template molecules. After the experimental conditions were optimized, two linear relationship were obtained covering the concentration range of 2.0-10.0 ?M and 10.0-90.0 ?M, and the limit of detection (LOD) for LC was found to be 1.76 ?M. Furthermore, a possible mechanism was put forward to explain the fluorescence quenching of YVO4:Eu(3+)@MIPs. More importantly, the obtained sensor was proven to be suitable for the detection of residues of LC in real examples. And the excellent performance of this sensor will facilitate future development of rapid and high-efficiency detection of LC. PMID:24840409

  7. Simple and sensitive fluorescence detection of the RNA endonuclease activity of mammalian argonaute2 protein based on an RNA molecular beacon.

    PubMed

    Li, Feng; Li, Peng; Yang, Limin; Tang, Bo

    2012-12-28

    A new strategy for determining the RNA endonuclease activity of mammalian argonaute2 (Ago2) protein has been developed, which combines the unique cleavage function of Ago2 protein with an RNA molecular beacon (RMB). Through the fluorescence restoration of the RMB, simple and sensitive detection of Ago2 is achieved. PMID:23145433

  8. Simple time-saving method for iron determination based on fluorescence quenching of an azaflavanon-3-ol compound.

    PubMed

    Ba?o?lu, Aysel; Tosun, Gonca; Ocak, Miraç; Alp, Hakan; Yayl?, Nurettin; Ocak, Ümmühan

    2015-03-18

    A simple and time-saving spectrofluorometric method developed using an azaflavanon-3-ol compound was used for the determination of iron in various food samples. Nitric acid and hydrogen peroxide were used for digestion of samples in a closed microwave system. The method was validated by analyzing two certified reference materials (CRM-SA-C Sandy Soil C and Mixed Polish Herbs INCT-MPH-2). Measurements were carried out using a modified standard addition method. The standard addition graph was linear until 21.6 mg/L in the determination of iron(III). Detection and quantification limits were 0.81 and 2.4 mg/L, respectively. Satisfactory accuracy was obtained for spinach, dill, mint, purslane, rocket, red lentils, dry beans, and two iron medicinal tablets. High recoveries were found for streamwater samples fortified at three different concentrations. The method is simple, time-saving, cost-effective, and suitable for the determination of the iron content of foods. PMID:25723252

  9. Fluorescence-Based Sensors

    NASA Astrophysics Data System (ADS)

    Orellana, Guillermo

    The natural luminescent phenomena (from the Latin words "lumen" and "essentia", i.e., "made of light") such as northern lights (aurora borealis), marine brightness, glow-worms, shining putrid fish scales, "bluish"- appearing water when contained in certain wooden cups (quinine fluorescence), some stones heated at high temperatures with reducing agents (BaS phosphorescence), or light emitted while crushing sugar (triboluminescence) already fascinated our ancestors. Nowadays we understand that ultraviolet and visible emission of light originates from a competitive deactivation pathway of the lowest electronic excited state of atoms and molecules that produces the so called luminescence (the sub-terms fluorescence and phosphorescence just designate whether the return of the excited to the ground state is an "allowed" or "forbidden" process, namely it is fast or slow, the loosely-defined border between them being a 1-?s-1 rate constant). Actually, luminescence is the only method to generate light in the known Universe regardless it is powered by the nuclear reactions in the stars, the ohmical heating in bulbs, an electric discharge, the absorption of light or a (bio)chemical reaction (chemiluminescence).

  10. Aptamer-Based Fluorescent Biosensors

    PubMed Central

    Wang, Rongsheng E.; Zhang, Yin; Cai, Jianfeng; Cai, Weibo; Gao, Ting

    2011-01-01

    Selected from random pools of DNA or RNA molecules through systematic evolution of ligands by exponential enrichment (SELEX), aptamers can bind to target molecules with high affinity and specificity, which makes them ideal recognition elements in the development of biosensors. To date, aptamer-based biosensors have used a wide variety of detection techniques, which are briefly summarized in this article. The focus of this review is on the development of aptamer-based fluorescent biosensors, with emphasis on their design as well as properties such as sensitivity and specificity. These biosensors can be broadly divided into two categories: those using fluorescently-labeled aptamers and others that employ label-free aptamers. Within each category, they can be further divided into “signal-on” and “signal-off” sensors. A number of these aptamer-based fluorescent biosensors have shown promising results in biological samples such as urine and serum, suggesting their potential applications in biomedical research and disease diagnostics. PMID:21838688

  11. Fluorescent sensors based on boronic acids

    NASA Astrophysics Data System (ADS)

    Cooper, Christopher R.; James, Tony D.

    1999-05-01

    Sensor systems have long been needed for detecting the presence in solution of certain chemically or biologically important species. Sensors are used in a wide range of applications from simple litmus paper that shows a single color change in acidic or basic environments to complex biological assays that use enzymes, antibodies and antigens to display binding events. With this work the use of boronic acids in the design and synthesis of sensors for saccharides (diols) will be presented. The fluorescent sensory systems rely on photoinduced electron transfer (PET) to modulate the observed fluorescence. When saccharides form cyclic boronate esters with boronic acids, the Lewis acidity of the boronic acid is enhanced and therefore the Lewis acid-base interaction between the boronic acid and a neighboring amine is strengthened. The strength of this acid-base interaction modulates the PET from the amine (acting as a quencher) to anthracene (acting as a fluorophore). These compounds show increased fluorescence at neutral pH through suppression of the PET from nitrogen to anthracene on saccharide binding. The general strategy for the development of saccharide selective systems will be discussed. The potential of the boronic acid based systems will be illustrated using the development of glucose and glucosamine selective fluorescent sensors as examples.

  12. Highly Selective and Sensitive Detection of Hg(II) from HgCl2 by a Simple Rhodamine-Based Fluorescent Sensor.

    PubMed

    Mao, Yan; Hong, Miaomiao; Liu, Aifeng; Xu, Dongmei

    2015-05-01

    N-acryloyl rhodamine B hydrazide, a non-responsive control of a colorimetric Cu(2+) sensor, was used as a turn-on fluorescent sensor for Hg(II) from HgCl2 in the presence of AgNO3. The detection was highly selective and sensitive, and a large number of environmentally and biologically relevant metal ions, such as Na(+), K(+), Ca(2+), Mg(2+), Fe(3+), Cu(2+), Zn(2+), Cr(3+), Pb(2+), Ni(2+), Fe(2+), Mn(2+), Co(2+), Cd(2+), including Hg(II) from the easy dissociated salts, did not show significant interference. The fluorescence of the sensor (10 ?M) was enhanced 74 folds by 10 equiv. of Hg(II) from HgCl2 in THF/HAc-NaAc (1/1, v/v, pH?=?6) aqueous buffer solution containing 20 equiv. of AgNO3. The maximal fluorescence intensity increased linearly with the concentration of Hg(II) in the range of 0-70 ?M. The detection limit of Hg(II) was 0.59 ?M. The sensing mechanism was explored by Job's plot experiment, reversible experiment, mass spectrum analysis, spectroscopic analysis, and thin-layer chromatography. PMID:25822190

  13. Lens-based fluorescence nanoscopy.

    PubMed

    Eggeling, Christian; Willig, Katrin I; Sahl, Steffen J; Hell, Stefan W

    2015-05-01

    The majority of studies of the living cell rely on capturing images using fluorescence microscopy. Unfortunately, for centuries, diffraction of light was limiting the spatial resolution in the optical microscope: structural and molecular details much finer than about half the wavelength of visible light (~200 nm) could not be visualized, imposing significant limitations on this otherwise so promising method. The surpassing of this resolution limit in far-field microscopy is currently one of the most momentous developments for studying the living cell, as the move from microscopy to super-resolution microscopy or 'nanoscopy' offers opportunities to study problems in biophysical and biomedical research at a new level of detail. This review describes the principles and modalities of present fluorescence nanoscopes, as well as their potential for biophysical and cellular experiments. All the existing nanoscopy variants separate neighboring features by transiently preparing their fluorescent molecules in states of different emission characteristics in order to make the features discernible. Usually these are fluorescent 'on' and 'off' states causing the adjacent molecules to emit sequentially in time. Each of the variants can in principle reach molecular spatial resolution and has its own advantages and disadvantages. Some require specific transitions and states that can be found only in certain fluorophore subfamilies, such as photoswitchable fluorophores, while other variants can be realized with standard fluorescent labels. Similar to conventional far-field microscopy, nanoscopy can be utilized for dynamical, multi-color and three-dimensional imaging of fixed and live cells, tissues or organisms. Lens-based fluorescence nanoscopy is poised for a high impact on future developments in the life sciences, with the potential to help solve long-standing quests in different areas of scientific research. PMID:25998828

  14. Ultrasound-modulated fluorescence based on fluorescent microbubbles.

    PubMed

    Liu, Yuan; Feshitan, Jameel A; Wei, Ming-Yuan; Borden, Mark A; Yuan, Baohong

    2014-08-01

    Ultrasound-modulated fluorescence (UMF) imaging has been proposed to provide fluorescent contrast while maintaining ultrasound resolution in an optical-scattering medium (such as biological tissue). The major challenge is to extract the weakly modulated fluorescent signal from a bright and unmodulated background. UMF was experimentally demonstrated based on fluorophore-labeled microbubble contrast agents. These contrast agents were produced by conjugating N-hydroxysuccinimide (NHS)-ester-attached fluorophores on the surface of amine-functionalized microbubbles. The fluorophore surface concentration was controlled so that a significant self-quenching effect occurred when no ultrasound was applied. The intensity of the fluorescent emission was modulated when microbubbles were oscillated by ultrasound pulses, presented as UMF signal. Our results demonstrated that the UMF signals were highly dependent on the microbubbles' oscillation amplitude and the initial surface fluorophore-quenching status. A maximum of ?42% UMF modulation depth was achieved with a single microbubble under an ultrasound peak-to-peak pressure of 675 kPa. Further, UMF was detected from a 500-?m tube filled with contrast agents in water and scattering media with ultrasound resolution. These results indicate that ultrasound-modulated fluorescent microbubble contrast agents can potentially be used for fluorescence-based molecular imaging with ultrasound resolution in the future. PMID:25104407

  15. A simple procedure to improve the surface passivation for single molecule fluorescence studies

    NASA Astrophysics Data System (ADS)

    Pan, Hai; Xia, Yifan; Qin, Meng; Cao, Yi; Wang, Wei

    2015-07-01

    The single-molecule fluorescence technique is becoming a general and mature tool to probe interactions and dynamics of biomolecules with ultra high precision and accuracy. However, nonspecific adsorption of biomolecules to the flow cells remains a major experimental riddle for the study of many complex biological systems, especially those exhibiting low binding affinity and presenting with weakly populated intermediates. Many novel surface passivation methods have been introduced to reduce nonspecific interactions. Here, we present an effective and inexpensive method to significantly reduce nonspecific binding of biomolecules in conventional poly (ethylene glycol) (PEG)–based surface passivation protocols, without additional exogenous effects. In particular, we propose a simple 10 min Tween-20 treatment for the PEG passivated surface, which could further increase the hydrophilicity of the surface and thus promote passivation efficacy by about 5 to 10 times. We anticipate that this new procedure will find broad practical applications and extend the current reaches of single-molecule fluorescence studies.

  16. A simple chlorophyll fluorescence parameter that correlates with the rate coefficient of photoinactivation of photosystem II.

    PubMed

    Hendrickson, Luke; Förster, Britta; Pogson, Barry J; Chow, Wah Soon

    2005-06-01

    A method of partitioning the energy in a mixed population of active and photoinactivated Photosystem II (PS II) complexes based on chlorophyll fluorescence measurements is presented. There are four energy fluxes, each with its quantum efficiency: a flux associated with photochemical electron flow in active PS II reaction centres (JPS II), thermal dissipation in photoinactivated, non-functional PS IIs (JNF), light-regulated thermal dissipation in active PS IIs (JNPQ) and a combined flux of fluorescence and constitutive, light-independent thermal dissipation (Jf,D). The four quantum efficiencies add up to 1.0, without the need to introduce an 'excess' term E, which in other studies has been claimed to be linearly correlated with the rate coefficient of photoinactivation of PS II (kpi). We examined the correlation of kpi with various fluxes, and found that the combined flux (JNPQ + Jf,D= Jpi) is as well correlated with kpi as is E. This combined flux arises from Fs/Fm ', the ratio of steady-state to maximum fluorescence during illumination, which represents the quantum efficiency of combined non-photochemical dissipation pathways in active PS IIs. Since Fs/Fm ' or its equivalent, Jpi, is a likely source of events leading to photoinactivation of PS II, we conclude that Fs/Fm ' is a simple predictor of kpi. PMID:16049753

  17. A Simple and Sensitive Approach for Ochratoxin A Detection Using a Label-Free Fluorescent Aptasensor

    PubMed Central

    Lv, Zhenzhen; Chen, Ailiang; Liu, Jinchuan; Guan, Zheng; Zhou, Yu; Xu, Siyuan; Yang, Shuming; Li, Cheng

    2014-01-01

    Ochratoxin A(OTA) is found to be one of the predominant contaminating mycotoxins in a wide variety of food commodities. To avoid the risk of OTA consumption, the detection and quantitation of OTA level are of great significance. Based on the fact that ssDNA aptamer has the ability to form a double-strand structure with its complementary sequence, a simple and rapid aptamer-based label-free approach for highly sensitive and selective fluorescence detection of OTA was developed by using ultra-sensitive double-strand DNA specific dyes PicoGreen. The results showed that as low as 1 ng/mL of OTA could be detected with a dynamic range of more than 5 orders of magnitude which satisfies the requirements for OTA maximum residue limit in various food regulated by European Commission. With the specificity of aptamer, the assay exhibited high selectivity for OTA against two other analogues (N-acetyl-l-phenylalanine and zearalenone). We also tested the aptasensor practicability using real sample of 1% beer spiked with a series of concentration of OTA and the results show good tolerance to matrix effect. All detections could be achieved in less than 30 min, which provides a simple, quick and sensitive detection method for OTA screening in food safety and could be easily extend to other small molecular chemical compounds detection which aptamer has been selected. PMID:24465818

  18. A simple, rapid, and sensitive fluorescence assay for microsomal triglyceride transfer protein

    Microsoft Academic Search

    Humra Athar; Jahangir Iqbal; Xian-Cheng Jiang; M. Mahmood Hussain

    2004-01-01

    Microsomal triglyceride transfer protein (MTP) is critical for the assembly and secretion of apolipoprotein B (apoB) lipoproteins. Its activity is classically measured by incubating purified MTP or cellular homogenates with do- nor vesicles containing radiolabeled lipids, precipitating the donor vesicles, and measuring the radioactivity transferred to acceptor vesicles. Here, we describe a simple, rapid, and sensitive fluorescence assay for MTP.

  19. Accurate quantification of fluorescent targets within turbid media based on a decoupled fluorescence Monte Carlo model.

    PubMed

    Deng, Yong; Luo, Zhaoyang; Jiang, Xu; Xie, Wenhao; Luo, Qingming

    2015-07-01

    We propose a method based on a decoupled fluorescence Monte Carlo model for constructing fluorescence Jacobians to enable accurate quantification of fluorescence targets within turbid media. The effectiveness of the proposed method is validated using two cylindrical phantoms enclosing fluorescent targets within homogeneous and heterogeneous background media. The results demonstrate that our method can recover relative concentrations of the fluorescent targets with higher accuracy than the perturbation fluorescence Monte Carlo method. This suggests that our method is suitable for quantitative fluorescence diffuse optical tomography, especially for in vivo imaging of fluorophore targets for diagnosis of different diseases and abnormalities. PMID:26125384

  20. Simple super-resolution live-cell imaging based on diffusion-assisted Forster

    E-print Network

    Ihee, Hyotcherl

    Simple super-resolution live-cell imaging based on diffusion-assisted Fo¨rster resonance energy present a very simple, rapid, general and cost-efficient super-resolution imaging method, which can otherwise spatially overlapped fluorescence signals and allowing super-resolution imaging. The proposed

  1. Imaging of the fluorescence spectrum of a single fluorescent molecule by prism-based spectroscopy

    Microsoft Academic Search

    Yoshikazu Suzuki; Tomomi Tani; Kazuo Sutoh; Shinji Kamimura

    2002-01-01

    We have devised a novel method to visualize the fluorescence spectrum of a single fluorescent molecule using prism-based spectroscopy. Equiping a total internal reflection microscope with a newly designed wedge prism, we obtained a spectral image of a single rhodamine red molecule attached to an essential light chain of myosin. We also obtained a spectral image of single-pair fluorescence resonance

  2. Adaptive finite element based tomography for fluorescence optical

    E-print Network

    Bangerth, Wolfgang

    Adaptive finite element based tomography for fluorescence optical imaging in tissue Amit Joshi,1@ices.utexas.edu, eva-m-sevick@tamu.edu Abstract: A three-dimensional fluorescence-enhanced optical tomogra- phy scheme based upon an adaptive finite element formulation is developed and employed to reconstruct fluorescent

  3. Portable optical oxygen sensor based on time-resolved fluorescence.

    PubMed

    Chu, Cheng-Shane; Chu, Ssu-Wei

    2014-11-10

    A new, simple signal processing, low-cost technique for the fabrication of a portable oxygen sensor based on time-resolved fluorescence is described. The sensing film uses the oxygen sensing dye platinum meso-tetra (pentfluorophenyl) porphyrin (PtTFPP) embedded in a polymer matrix. The ratio ?0/?100 measures sensitivity of the sensing film, where ?0 and ?100 represent the detected fluorescence lifetimes from the sensing film exposed to 100% nitrogen and 100% oxygen, respectively. The experimental results reveal that the PtTFPP-doped oxygen sensor has a sensitivity of 2.2 in the 0%-100% range. A preparation procedure for coating the photodiodes with the oxygen sensor film that produces repetitive and reliable sensing devices is proposed. The developed time-resolved optical oxygen sensor is portable, low-cost, has simple signal processing, and lacks optical filter elements. It is a cost-effective alternative to traditional electrochemical-based oxygen sensors and provides a platform for other optical based sensors. PMID:25402987

  4. A Fluorescence Based Dissolved Oxygen Sensor

    NASA Astrophysics Data System (ADS)

    McFarlane, Ronald; Hamilton, M. Coreen

    1987-10-01

    A sensor based on fluorescence quenching has been built to detect oxygen activity in gas and water. The sensor consists of a xenon flash bulb as a light source; an excitation wavelength band pass filter; a dichroic beam splitter; collimating and focussing lenses; a plastic clad silica (PCS) rod with the fluorophore immobilized at the tip of it; an emission wavelength band pass filter; a photomultiplier tube (PMT); a monitor PIN photodiode detector; and interface electronics to couple a computer to the rest of the sensor. The device demonstrates a reversible change in fluorescence quenching for changes in oxygen activity. The fluorescence signal seen by the PMT varies over a factor of 3, being highest at 0 oxygen activity and lowest at atmospheric oxygen activity. The device exhibits a 63 % response time of less than 1 second for gases and less than 10 seconds for oxygen dissolved in water. The noise floor of the sensor is approximately 1%. The present embodiment of the device was designed to allow the sensor to operate in the marine environment. The optical components, computer, batteries, and power supply circuitry are mounted on a rack that is enclosed in a pressure housing. The immobilized fluorophore is exposed to sea water. The light travels along the PCS rod, through a pressure seal, to the rest of the system. Present investigations are centered around long term stability of the fluorophore and constituents of the real ocean that will interfere with the quenching mechanism.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. The toolbox of fluorescence standards: flexible calibration tools for the standardization of fluorescence-based measurements

    NASA Astrophysics Data System (ADS)

    Resch-Genger, Ute; Hoffmann, K.; Würth, C.; Behnke, T.; Hoffmann, A.; Pfeifer, D.; Engel, A.

    2010-04-01

    To improve the reliability of fluorescence data in the life and material sciences and to enable accreditation of fluorescence techniques, standardization concepts are required that guarantee and improve the comparability of fluorescence measurements. At the core of such concepts are simple and evaluated fluorescence standards for the consideration of instrument-specific spectral and intensity distortions of measured signals and for instrument performance validation (IPV). Similarly in need are fluorescence intensity standards for the quantification from measured intensities and for signal referencing, thereby accounting for excitation light-induced intensity fluctuations. These standards should be preferably certified, especially for use in regulated areas like medical diagnostics. This encouraged us to develop liquid and solid standards for different fluorescence parameters and techniques for use under routine measurement conditions in different formates. Special emphasis was dedicated to the determination and control of the spectral responsivity of detection systems, wavelength accuracy, homogeneity of illumination, and intensity referencing for e.g. spectrofluorometers, fluorescence sensors and confocal laser scanning fluorescence microscopes. Here, we will present design concepts and examples for mono- and multifunctional fluorescence standards that provide traceability to radiometric units and present a first step towards a toolbox of standards.

  7. Fluorescence-lifetime-based sensing: applications to clinical chemistry and cellular imaging

    NASA Astrophysics Data System (ADS)

    Lakowicz, Joseph R.; Szmacinski, Henryk; Thompson, Richard B.

    1993-06-01

    Measurements of fluorescence lifetimes, rather than intensity or intensity ratios, offer many advantages in clinical chemistry and imaging. However, measurements of time-resolved fluorescence are normally associated with complex laser light sources and instrumentation. In this lecture, we show how emerging technology is enabling the design and use of simple instrumentation for time-resolved fluorescence. In particular, it is now possible to imagine lifetime-based measurements of blood gases and blood glucose, and lifetime imaging of calcium and other ions in microscopic samples.

  8. Quantum dots-based label-free fluorescence sensor for sensitive and non-enzymatic detection of caffeic acid.

    PubMed

    Xiang, Xia; Shi, Jianbin; Huang, Fenghong; Zheng, Mingming; Deng, Qianchun

    2015-08-15

    We have developed a label-free fluorescence sensor for caffeic acid (CA) by the use of CdTe:Zn(2+) quantum dots (CdTe:Zn(2+) QDs) as an output signal. The principle of sensor is based on the fluorescence quenching and binding properties of Fe(2+) toward QDs and CA, respectively. To provide a fluorescence turn-on mode for CA detection, Fe(2+) is first mixed with QDs solution, leading to a low fluorescence emission. With the addition of CA, the fluorescence of QDs is recovered due to the strong binding interaction between CA and Fe(2+). Thus, a QDs-based label-free fluorescence sensor, designed in a simple mix-and-detect format, is established for CA detection. This study demonstrated here not only offers simple, sensitive and non-enzymatic detection method for CA, but also brings to light a new application of QDs in the food analysis. PMID:25966400

  9. Turn-on fluorescent detection of cyanide based on the inner filter effect of silver nanoparticles.

    PubMed

    Shang, Li; Qin, Chuanjiang; Jin, Lihua; Wang, Lixiang; Dong, Shaojun

    2009-07-01

    A simple, sensitive fluorescent method for detecting cyanide has been developed based on the inner filter effect (IFE) of silver nanoparticles (Ag NPs). With a high extinction coefficient and tunable plasmon absorption feature, Ag NPs are expected to be a powerful absorber to tune the emission of the fluorophore in the IFE-based fluorescent assays. In the present work, we developed a turn-on fluorescent assay for cyanide based on the strong absorption of Ag NPs to both excitation and emission light of an isolated fluorescence indicator. In the presence of cyanide, the absorber Ag NPs will dissolve gradually, which then leads to recovery of the IFE-decreased emission of the fluorophore. The concentration of Ag NPs in the detection system was found to affect the fluorescence response toward cyanide greatly. Under the optimum conditions, the present IFE-based approach can detect cyanide ranging from 5.0 x 10(-7) to 6.0 x 10(-4) M with a detection limit of 2.5 x 10(-7) M, which is much lower than the corresponding absorbance-based approach and compares favorably with other reported fluorescent methods. In addition, the present method possesses a good selectivity for cyanide over other common anions and further application in cyanide-spiked water samples suggested a recovery between 98.2 and 101.4%. Therefore, our proposed IFE-based fluorescent method is expected to be applied for cyanide determination in practical applications. PMID:19562218

  10. Sensitive turn-on fluorescent detection of melamine based on fluorescence resonance energy transfer.

    PubMed

    Guo, Liangqia; Zhong, Jianhai; Wu, Jinmei; Fu, FengFu; Chen, Guonan; Chen, Yongxuan; Zheng, Xiaoyan; Lin, Song

    2011-04-21

    We here report a novel fluorescent method for the detection of melamine based on the high fluorescence quenching ability of gold nanoparticles. The fluorescence was significantly quenched via fluorescence resonance energy transfer when fluorescein molecules were attached to the surface of gold nanoparticles by electrostatic interaction. Upon addition of melamine, the fluorescence was enhanced due to the competitive adsorption of gold nanoparticles between melamine and fluorescein. Under the optimum conditions, the fluorescence enhancement efficiency [(I-I(0))/I(0)] showed a linear relationship with the concentration of melamine in the range of 1.0 × 10(-7) mol L(-1)~4.0 × 10(-6) mol L(-1), and the detection limit was calculated to be 1.0 × 10(-9) mol L(-1). The proposed method showed several advantages such as high sensitivity, short analysis time, low cost and ease of operation. PMID:21359305

  11. Quick and simple estimation of bacteria using a fluorescent paracetamol dimer-Au nanoparticle composite

    NASA Astrophysics Data System (ADS)

    Sahoo, Amaresh Kumar; Sharma, Shilpa; Chattopadhyay, Arun; Ghosh, Siddhartha Sankar

    2012-02-01

    Rapid, simple and sensitive detection of bacterial contamination is critical for safeguarding public health and the environment. Herein, we report an easy method of detection as well as enumeration of the bacterial cell number on the basis of fluorescence quenching of a non-antibacterial fluorescent nanocomposite, consisting of paracetamol dimer (PD) and Au nanoparticles (NPs), in the presence of bacteria. The composite was synthesized by reaction of paracetamol (p-hydroxyacetanilide) with HAuCl4. The Au NPs of the composite were characterized using UV-Vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction and selected area electron diffraction analysis. The paracetamol dimer in the composite showed emission peak at 435 nm when excited at 320 nm. The method successfully detected six bacterial strains with a sensitivity of 100 CFU mL-1. The Gram-positive and Gram-negative bacteria quenched the fluorescence of the composite differently, making it possible to distinguish between the two. The TEM analysis showed interaction of the composite with bacteria without any apparent damage to the bacteria. The chi-square test established the accuracy of the method. Quick, non-specific and highly sensitive detection of bacteria over a broad range of logarithmic dilutions within a short span of time demonstrates the potential of this method as an alternative to conventional methods.Rapid, simple and sensitive detection of bacterial contamination is critical for safeguarding public health and the environment. Herein, we report an easy method of detection as well as enumeration of the bacterial cell number on the basis of fluorescence quenching of a non-antibacterial fluorescent nanocomposite, consisting of paracetamol dimer (PD) and Au nanoparticles (NPs), in the presence of bacteria. The composite was synthesized by reaction of paracetamol (p-hydroxyacetanilide) with HAuCl4. The Au NPs of the composite were characterized using UV-Vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction and selected area electron diffraction analysis. The paracetamol dimer in the composite showed emission peak at 435 nm when excited at 320 nm. The method successfully detected six bacterial strains with a sensitivity of 100 CFU mL-1. The Gram-positive and Gram-negative bacteria quenched the fluorescence of the composite differently, making it possible to distinguish between the two. The TEM analysis showed interaction of the composite with bacteria without any apparent damage to the bacteria. The chi-square test established the accuracy of the method. Quick, non-specific and highly sensitive detection of bacteria over a broad range of logarithmic dilutions within a short span of time demonstrates the potential of this method as an alternative to conventional methods. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11837h

  12. Intracellular pH measurements made simple by fluorescent protein probes and the phasor approach to fluorescence lifetime imaging.

    PubMed

    Battisti, Antonella; Digman, Michelle A; Gratton, Enrico; Storti, Barbara; Beltram, Fabio; Bizzarri, Ranieri

    2012-05-25

    A versatile pH-dependent fluorescent protein was applied to intracellular pH measurements by means of the phasor approach to fluorescence lifetime imaging. By this fit-less method we obtain intracellular pH maps under resting or altered physiological conditions by single-photon confocal or two-photon microscopy. PMID:22517076

  13. A FLUORESCENCE BASED ASSAY FOR DNA DAMAGE INDUCED BY STYRENE OXIDE

    EPA Science Inventory

    A rapid and simple assay to detect DNA damage to calf thymus DNA caused by styrene oxide (SO) is reported. This assay is based on changes observed in the melting and annealing behavior of the damaged DNA. The melting annealing process was monitored using a fluorescence indicat...

  14. A simple and rapid protocol for measuring neutral lipids in algal cells using fluorescence.

    PubMed

    Storms, Zachary J; Cameron, Elliot; de la Hoz Siegler, Hector; McCaffrey, William C

    2014-01-01

    Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal fermentation processes and screening for new oil-rich strains requires a fast and reliable protocol for determination of intracellular lipid content. Current practices rely largely on gravimetric methods to determine oil content, techniques developed decades ago that are time consuming and require large sample volumes. In this paper, Nile Red, a fluorescent dye that has been used to identify the presence of lipid bodies in numerous types of organisms, is incorporated into a simple, fast, and reliable protocol for measuring the neutral lipid content of Auxenochlorella protothecoides, a green alga. The method uses ethanol, a relatively mild solvent, to permeabilize the cell membrane before staining and a 96 well micro-plate to increase sample capacity during fluorescence intensity measurements. It has been designed with the specific application of monitoring bioprocess performance. Previously dried samples or live samples from a growing culture can be used in the assay. PMID:24961928

  15. A fluorescence lifetime-based solid sensor for water

    Microsoft Academic Search

    Qing Chang; Zakir Murtaza; Joseph R. Lakowicz; Govind Rao

    1997-01-01

    A fluorescence lifetime-based water sensor was developed, based on a solvent-polarity-sensitive fluorescent metal-ligand compound, dipyridol[3,2-a:2?,3?-c]phenazine, di[cis-l,2-bis(diphenylphosphino)-ethylene] osmium(II) hexafluorophosphate, [Os(dppz)(dppe)2](PF6)2. When excited in acetone solution, the compound emitted orange-red fluorescence with a peak wavelength of 610 nm. Fluorescence quenching was observed from both intensity and lifetime measurements when water was presented in the acetone. To fabricate a water sensor, the compound

  16. Homogeneous fluorescence-based immunoassay via inner filter effect of gold nanoparticles on fluorescence of CdTe quantum dots.

    PubMed

    Cui, Xiang; Liu, Mei; Li, Baoxin

    2012-07-21

    Homogeneous immunoassays are becoming more and more attractive for modern medical diagnosis because they are superior to heterogeneous immunoassays in sample and reagent consumption, analysis time, portability and disposability. Herein, a universal platform for homogeneous immunoassay, using human immunoglobulin (IgG) as a model analyte, has been developed. This assay relies upon the inner filter effect (IFE) of gold nanoparticles (AuNPs) on CdTe QDs fluorescence. The immunoreaction of antigen and antibody can induce the aggregation of antibody-functionalized AuNPs, and after aggregation the IFE of AuNPs on CdTe QDs fluorescence is greatly enhanced, resulting in a decrease of fluorescence intensity in the system. Based on this phenomenon, a wide dynamic range of 1-100 pg mL(-1) for determination of IgG can be obtained. The proposed method shows a detection limit of 0.3 pg mL(-1) for human IgG, which is much lower than the corresponding absorbance-based approach and compares favorably with other reported fluorescent methods. This immunoassay method is simple, rapid, cheap, and sensitive. The proposed method has been successfully applied to measuring IgG in serum samples, and the obtained results agreed well with those of the enzyme-linked immunosorbent assay (ELISA). PMID:22655288

  17. Characterization of flavin-based fluorescent proteins: an emerging class of fluorescent reporters.

    PubMed

    Mukherjee, Arnab; Walker, Joshua; Weyant, Kevin B; Schroeder, Charles M

    2013-01-01

    Fluorescent reporter proteins based on flavin-binding photosensors were recently developed as a new class of genetically encoded probes characterized by small size and oxygen-independent maturation of fluorescence. Flavin-based fluorescent proteins (FbFPs) address two major limitations associated with existing fluorescent reporters derived from the green fluorescent protein (GFP)-namely, the overall large size and oxygen-dependent maturation of fluorescence of GFP. However, FbFPs are at a nascent stage of development and have been utilized in only a handful of biological studies. Importantly, a full understanding of the performance and properties of FbFPs as a practical set of biological probes is lacking. In this work, we extensively characterize three FbFPs isolated from Pseudomonas putida, Bacillus subtilis, and Arabidopsis thaliana, using in vitro studies to assess probe brightness, oligomeric state, maturation time, fraction of fluorescent holoprotein, pH tolerance, redox sensitivity, and thermal stability. Furthermore, we validate FbFPs as stable molecular tags using in vivo studies by constructing a series of FbFP-based transcriptional constructs to probe promoter activity in Escherichia coli. Overall, FbFPs show key advantages as broad-spectrum biological reporters including robust pH tolerance (4-11), thermal stability (up to 60°C), and rapid maturation of fluorescence (<3 min.). In addition, the FbFP derived from Arabidopsis thaliana (iLOV) emerged as a stable and nonperturbative reporter of promoter activity in Escherichia coli. Our results demonstrate that FbFP-based reporters have the potential to address key limitations associated with the use of GFP, such as pH-sensitive fluorescence and slow kinetics of fluorescence maturation (10-40 minutes for half maximal fluorescence recovery). From this view, FbFPs represent a useful new addition to the fluorescent reporter protein palette, and our results constitute an important framework to enable researchers to implement and further engineer improved FbFP-based reporters with enhanced brightness and tighter flavin binding, which will maximize their potential benefits. PMID:23741385

  18. Characterization of Flavin-Based Fluorescent Proteins: An Emerging Class of Fluorescent Reporters

    PubMed Central

    Mukherjee, Arnab; Schroeder, Charles M.

    2013-01-01

    Fluorescent reporter proteins based on flavin-binding photosensors were recently developed as a new class of genetically encoded probes characterized by small size and oxygen-independent maturation of fluorescence. Flavin-based fluorescent proteins (FbFPs) address two major limitations associated with existing fluorescent reporters derived from the green fluorescent protein (GFP)–namely, the overall large size and oxygen-dependent maturation of fluorescence of GFP. However, FbFPs are at a nascent stage of development and have been utilized in only a handful of biological studies. Importantly, a full understanding of the performance and properties of FbFPs as a practical set of biological probes is lacking. In this work, we extensively characterize three FbFPs isolated from Pseudomonas putida, Bacillus subtilis, and Arabidopsis thaliana, using in vitro studies to assess probe brightness, oligomeric state, maturation time, fraction of fluorescent holoprotein, pH tolerance, redox sensitivity, and thermal stability. Furthermore, we validate FbFPs as stable molecular tags using in vivo studies by constructing a series of FbFP-based transcriptional constructs to probe promoter activity in Escherichia coli. Overall, FbFPs show key advantages as broad-spectrum biological reporters including robust pH tolerance (4–11), thermal stability (up to 60°C), and rapid maturation of fluorescence (<3 min.). In addition, the FbFP derived from Arabidopsis thaliana (iLOV) emerged as a stable and nonperturbative reporter of promoter activity in Escherichia coli. Our results demonstrate that FbFP-based reporters have the potential to address key limitations associated with the use of GFP, such as pH-sensitive fluorescence and slow kinetics of fluorescence maturation (10–40 minutes for half maximal fluorescence recovery). From this view, FbFPs represent a useful new addition to the fluorescent reporter protein palette, and our results constitute an important framework to enable researchers to implement and further engineer improved FbFP-based reporters with enhanced brightness and tighter flavin binding, which will maximize their potential benefits. PMID:23741385

  19. Naphthoxazole-based singlet oxygen fluorescent probes.

    PubMed

    Ruiz-González, Rubén; Zanocco, Renzo; Gidi, Yasser; Zanocco, Antonio L; Nonell, Santi; Lemp, Else

    2013-01-01

    In this study, we report the synthesis and photochemical behavior of a new family of photoactive compounds to assess its potential as singlet oxygen ((1)O2) probes. The candidate dyads are composed by a (1)O2 trap plus a naphthoxazole moiety linked directly or through an unsaturated bond to the oxazole ring. In the native state, the inherent great fluorescence of the naphthoxazole moiety is quenched; but in the presence of (1)O2, generated by the addition and appropriate irradiation of an external photosensitizer, a photooxidation reaction occurs leading to the formation of a new chemical entity whose fluorescence is two orders of magnitude higher than that of the initial compound, at the optimal selected wavelength. The presented dyads outperform the commonly used indirect fluorescent (1)O2 probes in terms of fluorescence enhancement maintaining the required specificity for (1)O2 detection in solution. PMID:23730728

  20. Improvements in LED-based fluorescence analysis systems

    Microsoft Academic Search

    Andrew E. Moe; Steve Marx; Naureen Banani; Matthew Liu; Brian Marquardt; Denise M. Wilson

    2005-01-01

    This paper presents results from an electronic interface that significantly improves the stability, power output, and spectral flexibility of light emitting diode (LED)-based systems used to excite fluorescence or other forms of luminescence. LEDs are an attractive alternative to conventional white-light sources used in fluorescence analysis because of reduced power of operation, enhanced modularity, reduced optical loss, fewer imaging artifacts,

  1. A simple but highly efficient multi-formyl phenol-amine system for fluorescence detection of peroxide explosive vapour.

    PubMed

    Xu, Wei; Fu, Yanyan; Gao, Yixun; Yao, Junjun; Fan, Tianchi; Zhu, Defeng; He, Qingguo; Cao, Huimin; Cheng, Jiangong

    2015-06-23

    A simple, highly stable, sensitive and selective fluorescent system for peroxide explosives was developed via an aromatic aldehyde oxidation reaction. The high efficiency arises from its higher HOMO level and multiple H-bonding. The sensitivity is obtained to be 0.1 ppt for H2O2 and 0.2 ppb for TATP. PMID:26054635

  2. Simple, Script-Based Science Processing Archive

    NASA Technical Reports Server (NTRS)

    Lynnes, Christopher; Hegde, Mahabaleshwara; Barth, C. Wrandle

    2007-01-01

    The Simple, Scalable, Script-based Science Processing (S4P) Archive (S4PA) is a disk-based archival system for remote sensing data. It is based on the data-driven framework of S4P and is used for data transfer, data preprocessing, metadata generation, data archive, and data distribution. New data are automatically detected by the system. S4P provides services such as data access control, data subscription, metadata publication, data replication, and data recovery. It comprises scripts that control the data flow. The system detects the availability of data on an FTP (file transfer protocol) server, initiates data transfer, preprocesses data if necessary, and archives it on readily available disk drives with FTP and HTTP (Hypertext Transfer Protocol) access, allowing instantaneous data access. There are options for plug-ins for data preprocessing before storage. Publication of metadata to external applications such as the Earth Observing System Clearinghouse (ECHO) is also supported. S4PA includes a graphical user interface for monitoring the system operation and a tool for deploying the system. To ensure reliability, S4P continuously checks stored data for integrity, Further reliability is provided by tape backups of disks made once a disk partition is full and closed. The system is designed for low maintenance, requiring minimal operator oversight.

  3. Mosaic-Detector-Based Fluorescence Spectral Imager

    NASA Technical Reports Server (NTRS)

    Son, Kyung-Ah; Moon, Jeong

    2007-01-01

    A battery-powered, pen-sized, portable instrument for measuring molecular fluorescence spectra of chemical and biological samples in the field has been proposed. Molecular fluorescence spectroscopy is among the techniques used most frequently in laboratories to analyze compositions of chemical and biological samples. Heretofore, it has been possible to measure fluorescence spectra of molecular species at relative concentrations as low as parts per billion (ppb), with a few nm spectral resolution. The proposed instrument would include a planar array (mosaic) of detectors, onto which a fluorescence spectrum would be spatially mapped. Unlike in the larger laboratory-type molecular fluorescence spectrometers, mapping of wavelengths to spatial positions would be accomplished without use of relatively bulky optical parts. The proposed instrument is expected to be sensitive enough to enable measurement of spectra of chemical species at relative concentrations <1 ppb, with spectral resolution that could be tailored by design to be comparable to a laboratory molecular fluorescence spectrometer. The proposed instrument (see figure) would include a button-cell battery and a laser diode, which would generate the monochromatic ultraviolet light needed to excite fluorescence in a sample. The sample would be held in a cell bounded by far-ultraviolet-transparent quartz or optical glass. The detector array would be, more specifically, a complementary metal oxide/ semiconductor or charge-coupled- device imaging photodetector array, the photodetectors of which would be tailored to respond to light in the wavelength range of the fluorescence spectrum to be measured. The light-input face of the photodetector array would be covered with a matching checkerboard array of multilayer thin film interference filters, such that each pixel in the array would be sensitive only to light in a spectral band narrow enough so as not to overlap significantly with the band of an adjacent pixel. The wavelength interval between adjacent pixels (and, thus, the spectral resolution) would typically be chosen by design to be approximately equal to the width of the total fluorescence wavelength range of interest divided by the number of pixels. The unitary structure comprising the photodetector array overlaid with the matching filter array would be denoted a hyperspectral mosaic detector (HMD) array.

  4. A WS2 nanosheet-based platform for fluorescent DNA detection via PNA-DNA hybridization.

    PubMed

    Wang, Shuting; Zhang, Yulin; Ning, Yong; Zhang, Guo-Jun

    2015-01-21

    The WS2 nanosheet, a two-dimensional layered nanomaterial, shows high fluorescence quenching ability for the dye-labeled ssDNA. Currently, most of the fluorescent DNA detection methods employ DNA as a probe for recognition of target DNA. Peptide nucleic acid (PNA) is a DNA mimic but a neutral molecule, showing superior hybridization properties to target DNA. Based on the unique properties of WS2 nanosheet and PNA-DNA hybridization, we have developed a rapid, simple, stable and sensitive approach for DNA detection based on good fluorescence quenching ability of the WS2 nanosheet as well as high binding affinity and specificity of PNA to DNA. This novel assay is capable of exhibiting high sensitivity and specificity with a detection limit of 500 pM, and discriminating between single bases. PMID:25426801

  5. Simple process of hybrid white quantum dot/organic light-emitting diodes by using quantum dot plate and fluorescence

    NASA Astrophysics Data System (ADS)

    Lee, Ho Won; Lee, Ki-Heon; Lee, Jae Woo; Kim, Jong-Hoon; Yang, Heesun; Kim, Young Kwan

    2015-02-01

    In this work, the simple process of hybrid quantum dot (QD)/organic light-emitting diode (OLED) was proposed to apply a white illumination light by using QD plate and organic fluorescence. Conventional blue fluorescent OLEDs were firstly fabricated and then QD plates of various concentrations, which can be controlled of UV–vis absorption and photoluminescence spectrum, were attached under glass substrate of completed blue devices. The suggested process indicates that we could fabricate the white device through very simple process without any deposition of orange or red organic emitters. Therefore, this work would be demonstrated that the potential simple process for white applications can be applied and also can be extended to additional research on light applications.

  6. Fluorescent Sensors for Zn2+ Based on a Fluorescein Platform

    E-print Network

    Tsien, Roger Y.

    Fluorescent Sensors for Zn2+ Based on a Fluorescein Platform: Synthesis, Properties to the sensor, which inhibits a photoinduced electron transfer (PET) quenching pathway. The X-ray crystal properties § Massachusetts Institute of Technology. Department of Pharmacology, University of California

  7. Novel pyrazoline-based selective fluorescent probe for the detection of hydrazine

    NASA Astrophysics Data System (ADS)

    Zheng, Xiao-Xin; Wang, Sheng-Qing; Wang, Hao-Yan; Zhang, Rong-Rong; Liu, Jin-Ting; Zhao, Bao-Xiang

    2015-03-01

    A novel pyrazoline-based fluorescent probe, 2-[4-(3,5-diphenyl-4,5-dihydro-pyrazol-1-yl)-benzylidene]-malononitrile, with a simple structure and low detection limit (6.16 × 10-6 M) for the detection of hydrazine is designed and synthesized. The probe responds selectively to hydrazine over other molecules with marked fluorescence enhancement. The probe can detect hydrazine effectively at pH 5.0-9.0 with a special emission wavelength at 520 nm. Moreover, the probe can be used to detect hydrazine from variety of natural source water.

  8. Fluorescence quenching of Rhodamine B base by two amines

    NASA Astrophysics Data System (ADS)

    Bakkialakshmi, S.; Selvarani, P.; Chenthamarai, S.

    2013-03-01

    Fluorescence quenching of Rhodamine B base (RhB) in DMF solution has been studied at different concentrations of the amine Triethyl amine (TEA) and n-butyl amine (NBA) at room temperature. It has been observed that the fluorescence intensity of RhB decrease with increase in the concentration of the TEA and NBA. It has been observed that the quenching due to amines proceeds via dynamic quenching process. The rate constants for the quenching process have been calculated using Stern-Volmer equation. Time resolved fluorescence study and 1H NMR spectral study have also been carried out and discussed.

  9. Field portable mobile phone based fluorescence microscopy for detection of Giardia lamblia cysts in water samples

    NASA Astrophysics Data System (ADS)

    Ceylan Koydemir, Hatice; Gorocs, Zoltan; McLeod, Euan; Tseng, Derek; Ozcan, Aydogan

    2015-03-01

    Giardia lamblia is a waterborne parasite that causes an intestinal infection, known as giardiasis, and it is found not only in countries with inadequate sanitation and unsafe water but also streams and lakes of developed countries. Simple, sensitive, and rapid detection of this pathogen is important for monitoring of drinking water. Here we present a cost-effective and field portable mobile-phone based fluorescence microscopy platform designed for automated detection of Giardia lamblia cysts in large volume water samples (i.e., 10 ml) to be used in low-resource field settings. This fluorescence microscope is integrated with a disposable water-sampling cassette, which is based on a flow-through porous polycarbonate membrane and provides a wide surface area for fluorescence imaging and enumeration of the captured Giardia cysts on the membrane. Water sample of interest, containing fluorescently labeled Giardia cysts, is introduced into the absorbent pads that are in contact with the membrane in the cassette by capillary action, which eliminates the need for electrically driven flow for sample processing. Our fluorescence microscope weighs ~170 grams in total and has all the components of a regular microscope, capable of detecting individual fluorescently labeled cysts under light-emitting-diode (LED) based excitation. Including all the sample preparation, labeling and imaging steps, the entire measurement takes less than one hour for a sample volume of 10 ml. This mobile phone based compact and cost-effective fluorescent imaging platform together with its machine learning based cyst counting interface is easy to use and can even work in resource limited and field settings for spatio-temporal monitoring of water quality.

  10. Tryptophan-based chromophore in fluorescent proteins can be anionic

    PubMed Central

    Sarkisyan, Karen S.; Yampolsky, Ilia V.; Solntsev, Kyril M.; Lukyanov, Sergey A.; Lukyanov, Konstantin A.; Mishin, Alexander S.

    2012-01-01

    Cyan fluorescent proteins (CFP) with tryptophan66-based chromophore are widely used for live cell imaging. In contrast to green and red fluorescent proteins, no charged states of the CFP chromophore have been described. Here, we studied synthetic CFP chromophore and found that its indole group can be deprotonated rather easily (pKa 12.4).We then reproduced this effect in the CFP mCerulean by placing basic amino acids in the chromophore microenvironment. As a result, green-emitting variant with an anionic chromophore and key substitution Val61Lys was obtained. This is the first evidence strongly suggesting that tryptophan-based chromophores in fluorescent proteins can exist in an anionic charged state. Switching between protonated and deprotonated Trp66 in fluorescent proteins represents a new unexplored way to control their spectral properties. PMID:22934131

  11. Ultrasensitive Fluorescence-Based Detection of Nascent Proteins in Gels

    Microsoft Academic Search

    Sadanand Gite; Sergey Mamaev; Jerzy Olejnik; Kenneth Rothschild

    2000-01-01

    The most common method of analysis of proteins synthesized in a cell-free translation system (e.g., nascent proteins) involves the use of radioactive amino acids such as [35S]methionine or [14C]leucine. We report a sensitive, nonisotopic, fluorescence-based method for the detection of nascent proteins directly in polyacrylamide gels. A fluorescent reporter group is incorporated at the N-terminus of nascent proteins using an

  12. [Curve fitting based on genetic algorithms for quantitative resolution in overlapped fluorescence spectra].

    PubMed

    Xia, Xiang-hua; Sun, Han-wen

    2012-08-01

    The exponentially modified Gaussian (EMG) model-based genetic algorithm was used as a fitness function for fitting fluorescence spectrogram. The method was effective for solving the interference of fluorescent substance in the course of the multi-component quantitative analysis. As an example, the interference of endogenous fluorophores in different urines with the fluorescence of gatifloxacin (GFLX) was examined. A good eradicating efficacy was achieved by using the fitting fluorescence spectrogram. Under the optimized experimental conditions, the good linear relationship between the fluorescence intensity and GFLX concentration was obtained in the range of 0.06-3.5 microg x mL(-1) with a correlation coefficient of 0.9994. The detection limit and recovery were 0.02 microg x mL(-1) and 99.2%-109.4%, respectively, with the relative standard deviation from 1.3% to 2.7%. The proposed fitting fluorescence spectrometric method was rapid, simple and highly sensitive for the determination of GFLX in different human urine without preseparation. The recovery, selectivity, linearity, precision and accuracy of the method are convenient for routine assays and pharmacokinetic studies. PMID:23156772

  13. Wide field-of-view Talbot grid-based microscopy for multicolor fluorescence imaging

    PubMed Central

    Pang, Shuo; Han, Chao; Erath, Jessey; Rodriguez, Ana; Yang, Changhuei

    2013-01-01

    The capability to perform multicolor, wide field-of-view (FOV) fluorescence microscopy imaging is important in screening and pathology applications. We developed a microscopic slide-imaging system that can achieve multicolor, wide FOV, fluorescence imaging based on the Talbot effect. In this system, a light-spot grid generated by the Talbot effect illuminates the sample. By tilting the excitation beam, the Talbot-focused spot scans across the sample. The images are reconstructed by collecting the fluorescence emissions that correspond to each focused spot with a relay optics arrangement. The prototype system achieved an FOV of 12 × 10 mm2 at an acquisition time as fast as 23 s for one fluorescence channel. The resolution is fundamentally limited by spot size, with a demonstrated full-width at half-maximum spot diameter of 1.2 ?m. The prototype was used to image green fluorescent beads, double-stained human breast cancer SK-BR-3 cells, Giardia lamblia cysts, and the Cryptosporidium parvum oocysts. This imaging method is scalable and simple for implementation of high-speed wide FOV fluorescence microscopy. PMID:23787643

  14. Development of fluorescent lead II sensor based on an anthracene derived chalcone

    NASA Astrophysics Data System (ADS)

    Prabhu, J.; Velmurugan, K.; Nandhakumar, R.

    2015-06-01

    A simple anthracene based chalcone as a fluorescent chemosensor 1, capable of detecting Pb2+ in aqueous media, has been synthesized by the reaction between pyridine 2-carboxaldehyde and 9-acetyl anthracene. The Pb2+ recognition processes follows a photo induced electron transfer (PET) mechanism and are scarcely influenced by other coexisting metal ions. In addition, determination of lead in a variety of samples was also determined.

  15. Motor Oil Classification Based on Time-Resolved Fluorescence

    PubMed Central

    Mu, Taotao; Chen, Siying; Zhang, Yinchao; Guo, Pan; Chen, He; Meng, Fandong

    2014-01-01

    A time-resolved fluorescence (TRF) technique is presented for classifying motor oils. The system is constructed with a third harmonic Nd:YAG laser, a spectrometer, and an intensified charge coupled device (ICCD) camera. Steady-state and time-resolved fluorescence (TRF) measurements are reported for several motor oils. It is found that steady-state fluorescence is insufficient to distinguish the motor oil samples. Then contour diagrams of TRF intensities (CDTRFIs) are acquired to serve as unique fingerprints to identify motor oils by using the distinct TRF of motor oils. CDTRFIs are preferable to steady-state fluorescence spectra for classifying different motor oils, making CDTRFIs a particularly choice for the development of fluorescence-based methods for the discrimination and characterization of motor oils. The two-dimensional fluorescence contour diagrams contain more information, not only the changing shapes of the LIF spectra but also the relative intensity. The results indicate that motor oils can be differentiated based on the new proposed method, which provides reliable methods for analyzing and classifying motor oils. PMID:24988439

  16. Doped semiconductor nanocrystal based fluorescent cellular imaging probes

    NASA Astrophysics Data System (ADS)

    Maity, Amit Ranjan; Palmal, Sharbari; Basiruddin, Sk; Karan, Niladri Sekhar; Sarkar, Suresh; Pradhan, Narayan; Jana, Nikhil R.

    2013-05-01

    Doped semiconductor nanocrystals such as Mn doped ZnS, Mn doped ZnSe and Cu doped InZnS, are considered as new classes of fluorescent biological probes with low toxicity. Although the synthesis in high quality of such nanomaterials is now well established, transforming them into functional fluorescent probes remains a challenge. Here we report a fluorescent cellular imaging probe made of high quality doped semiconductor nanocrystals. We have identified two different coating approaches suitable for transforming the as synthesized hydrophobic doped semiconductor nanocrystals into water-soluble functional nanoparticles. Following these approaches we have synthesized TAT-peptide- and folate-functionalized nanoparticles of 10-80 nm hydrodynamic diameter and used them as a fluorescent cell label. The results shows that doped semiconductor nanocrystals can be an attractive alternative for conventional cadmium based quantum dots with low toxicity.Doped semiconductor nanocrystals such as Mn doped ZnS, Mn doped ZnSe and Cu doped InZnS, are considered as new classes of fluorescent biological probes with low toxicity. Although the synthesis in high quality of such nanomaterials is now well established, transforming them into functional fluorescent probes remains a challenge. Here we report a fluorescent cellular imaging probe made of high quality doped semiconductor nanocrystals. We have identified two different coating approaches suitable for transforming the as synthesized hydrophobic doped semiconductor nanocrystals into water-soluble functional nanoparticles. Following these approaches we have synthesized TAT-peptide- and folate-functionalized nanoparticles of 10-80 nm hydrodynamic diameter and used them as a fluorescent cell label. The results shows that doped semiconductor nanocrystals can be an attractive alternative for conventional cadmium based quantum dots with low toxicity. Electronic supplementary information available: Characterization details of coating and functionalisation of doped nanocrystals, property of functionalized nanocrystals, quantification of cell labeling and control labeling experiments. See DOI: 10.1039/c3nr00549f

  17. Comparison of forest Leaf Area Index retrieval based on simple ratio and reduced simple ratio

    Microsoft Academic Search

    Gaolong Zhu; Weimin Ju; Jing M. Chen; Yanlian Zhou; Xianfeng Li; Xiaochan Xu

    2010-01-01

    Leaf Area Index (LAI) is an essential parameter for process-based ecological and climate models. Spectral vegetation indices calculated from remote sensing data are widely used for LAI retrieval at large scales. The applicability of two vegetation indices, namely Simple Ratio (SR) and Reduced Simple Ration (RSR), for retrieving LAI at Maoershan mountain in Heilongjiang province of China was investigated through

  18. Spectral properties of a simple azine Schiff base and its sensing ability towards protic environment through hydrogen bonding interaction

    NASA Astrophysics Data System (ADS)

    Ray, Debarati; Dalapati, Sasanka; Guchhait, Nikhil

    2013-11-01

    A simple azine linkage containing Schiff base p-N,N-diethylaminobenzaldazine (PDEAB) has been synthesized and its spectroscopic properties have been investigated using steady state absorption and fluorescence measurement. Both the absorption and emission studies indicate that the compound PDEAB forms intermolecular hydrogen bond with protic solvents. The formation of intermolecular hydrogen bond between PDEAB and protic solvents is further verified by Quantum chemical calculation using Density Functional Theory (DFT) (B3LYP/6-31++G(d,p)) and Natural Bond Orbital (NBO) analysis. The non-fluorescent nature (fluorescence off) of PDEAB in aprotic environment can be switched over to a fluorescent system (fluorescence on) in presence of protic solvents and hence this molecule can be used as highly sensitive fluorosensor for protic solvent in aprotic medium like ACN or DOX.

  19. mb-FLIM: model-based fluorescence lifetime imaging

    NASA Astrophysics Data System (ADS)

    Zhao, Qiaole; Young, Ian Ted; Schouten, Raymond; Stallinga, Sjoerd; Jalink, Kees; de Jong, Sander

    2012-03-01

    We have developed a model-based, parallel procedure to estimate fluorescence lifetimes. Multiple frequencies are present in the excitation signal. Modeling the entire fluorescence and measurement process produces an analytical ratio of polynomials in the lifetime variable ?. A non-linear model-fitting procedure is then used to estimate ?. We have analyzed this model-based approach by simulating a 10 ?M fluorescein solution (? = 4 ns) and all relevant noise sources. We have used real LED data to drive the simulation. Using 240 ?s of data, we estimate ? = 3.99 ns. Preliminary experiments on real fluorescent images taken from fluorescein solutions (measured ? = 4.1 ns), green plastic test slides (measured ? = 3.0 ns), and GFP in U2OS (osteosarcoma) cells (measured ? = 2.1 ns) demonstrate that this model-based measurement technique works.

  20. MnO2 nanosheets based fluorescent sensing platform with organic dyes as a probe with excellent analytical properties.

    PubMed

    Wang, Chunxia; Zhai, Wanying; Wang, Yuexiang; Yu, Ping; Mao, Lanqun

    2015-06-21

    Manganese dioxide (MnO2) nanosheets have recently been demonstrated to be particularly attractive for fluorescent sensing and imaging; however, almost all MnO2 nanosheets-based fluorescent assays have been developed with emissive nanoparticles as the probes. In this study, we developed a novel strategy to use organic dyes, instead of emissive nanoparticles, as the probe to construct a platform for biosensing with excellent analytical properties. With 5-carboxyfluorescein (FAM) as a model organic dye, we firstly investigate the effect of MnO2 nanosheets on the fluorescence of FAM and find that the fluorescence intensity of FAM is considerably suppressed by MnO2 nanosheets based on the inner filter effect (IFE). To demonstrate that the MnO2 nanosheets-based fluorescence sensing platform can easily achieve a high selectivity with organic dyes as the probe, we use single-stranded DNA (ssDNA) oligonucleotide as a typical biorecognition unit, which is labeled with the FAM probe to form FAM-ssDNA. The fluorescent intensity of FAM-ssDNA is first suppressed by MnO2 nanosheets through the combination of IFE and Förster resonant energy transfer (FRET), and then recovered with subsequent hybridization with the complementary DNA oligonucleotide. To demonstrate the potential applications of the MnO2 nanosheets-based fluorescence sensing platform with organic dyes as the probes, we developed methods for simple but effective microRNA and thrombin assays. With the platform demonstrated here, the limits of detection for miR124a and thrombin are 0.8 nM and 11 nM, respectively. Moreover, the fluorescent sensing assay for thrombin exhibits high selectivity. This study essentially demonstrates a new 2D nanostructure-based fluorescent sensing platform that is robust, technically simple, and easily manipulated to achieve high selectivity and sensitivity for practical applications. PMID:25919222

  1. Fluorescence-based distributed chemical sensing for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Sinchenko, Elena I.; Gibbs, W. E. Keith; Stoddart, Paul R.

    2008-12-01

    Optical fiber distributed sensors hold great promise for corrosion monitoring in large structures. Systems based on absorption losses are relatively well developed, whereas fluorescence systems have been comparatively neglected due to the low efficiency of coupling light emitted in the cladding back into the core. This paper presents a model distributed corrosion sensor based on fluorescence detection by photon counting. The model predicts sufficient sensitivity for practical application under ideal conditions. Preliminary experimental results suggest that additional factors such as scattering at the core-cladding interface and mode distribution effects can have a significant deleterious effect on the performance in practice.

  2. Communication Networks Simple tariffs based on price multipliers for

    E-print Network

    Communication Networks Simple tariffs based on price multipliers for ATM VBR services COSTAS an approach for constructing simple time­based tariffs for Variable Bit Rate (VBR) connections from Constant tariffs for Service Level Agreements (SLAs) where the maximum amount of conforming traffic is given

  3. Communication Networks Simple tariffs based on price multipliers for

    E-print Network

    Communication Networks Simple tariffs based on price multipliers for ATM VBR services COSTAS an approach for constructing simple time-based tariffs for Variable Bit Rate (VBR) connections from Constant tariffs for Service Level Agreements (SLAs) where the maximum amount of conforming traffic is given

  4. Ultrasensitive fluorescence-based detection of nascent proteins in gels.

    PubMed

    Gite, S; Mamaev, S; Olejnik, J; Rothschild, K

    2000-03-15

    The most common method of analysis of proteins synthesized in a cell-free translation system (e.g., nascent proteins) involves the use of radioactive amino acids such as [(35)S]methionine or [(14)C]leucine. We report a sensitive, nonisotopic, fluorescence-based method for the detection of nascent proteins directly in polyacrylamide gels. A fluorescent reporter group is incorporated at the N-terminus of nascent proteins using an Escherichia coli initiator tRNA(fmet) misaminoacylated with methionine modified at the alpha-amino group. In addition to the normal formyl group, we find that the protein translational machinery accepts BODIPY-FL, a relatively small fluorophore with a high fluorescent quantum yield, as an N-terminal modification. Under the optimal conditions, fluorescent bands from nanogram levels of in vitro-produced proteins could be detected directly in gels using a conventional UV-transilluminator. Higher sensitivity ( approximately 100-fold) could be obtained using a laser-based fluorescent gel scanner. The major advantages of this approach include elimination of radioactivity and the rapid detection of the protein bands immediately after electrophoresis without any downstream processing. The ability to rapidly synthesize nascent proteins containing an N-terminal tag facilitates many biotechnological applications including functional analysis of gene products, drug discovery, and mutation screening. PMID:10706791

  5. Fluorescence lifetime-based glucose sensor using NADH

    NASA Astrophysics Data System (ADS)

    von Ketteler, A.; Siegberg, D.; Herten, D. P.; Horn, C.; Petrich, W.

    2012-03-01

    Fluorescence lifetime-based glucose sensing does not depend on fluctuations of the intensity of the light source, light scattering, or changes in the transmission of optical components. Here we demonstrate the sensing of glucose based on the fluorescence lifetime properties of dihydro nicotinamide adenine dinucleotide (NADH), which is reduced from NAD in the presence of glucose and glucose dehydrogenase. In particular we use the difference in the fluorescence properties of free and protein-bound NADH and calculate an average fluorescence lifetime, which arises from the two short lifetimes ?1=0.28ns and ?2=0.60ns (representing free NADH) and the longer lifetime of ?3=2.9ns (for the protein-bound NADH). While initial results were derived from measurements in aqueous solution, we also demonstrate the suitability of this method for determining the concentration of glucose in blood using test strips. We find that the average fluorescence lifetime changes linearly by a factor of 0.17 per 100mg/dl change in glucose concentration. As an alternative the ratio between free and protein-bound components Rs/l may also be used for quantification. Rs/l increases by a factor of 0.74 per 100mg/dl change in glucose concentration.

  6. Wireless Implantable Electronic Platform for Chronic Fluorescent-Based Biosensors

    Microsoft Academic Search

    Pietro Valdastri; Ekawahyu Susilo; Thilo Forster; Christof Strohhofer; Arianna Menciassi; Paolo Dario

    2011-01-01

    The development of a long-term wireless implantable biosensor based on fluorescence intensity measurement poses a number of technical challenges, ranging from biocompatibility to sensor stability over time. One of these challenges is the design of a power efficient and miniaturized electronics, enabling the biosen- sor to move from bench testing to long term validation, up to its final application in

  7. Frequency-domain fluorescence based fiber optic fire alarm system

    Microsoft Academic Search

    T. Sun; Z. Y. Zhang; K. T. V. Grattan

    2001-01-01

    Erbium and thulium doped fibers have been investigated in this work, for the first time, to determine their potential in fire or high temperature alarm applications based on the use of fluorescence decay in the frequency domain. Two configurations of the sensing system have been tested and compared, with particular reference to their minimum spatial resolution and location discrimination characteristics.

  8. A simple fluorescence quenching method for berberine determination using water-soluble CdTe quantum dots as probes

    NASA Astrophysics Data System (ADS)

    Cao, Ming; Liu, Meigui; Cao, Chun; Xia, Yunsheng; Bao, Linjun; Jin, Yingqiong; Yang, Song; Zhu, Changqing

    2010-03-01

    A novel method for the determination of berberine has been developed based on quenching of the fluorescence of thioglycolic acid-capped CdTe quantum dots (TGA-CdTe QDs) by berberine in aqueous solutions. Under optimum conditions, the relative fluorescence intensity was linearly proportional to the concentration of berberine between 2.5 × 10 -8 and 8.0 × 10 -6 mol L -1 with a detection limit of 6.0 × 10 -9 mol L -1. The method has been applied to the determination of berberine in real samples, and satisfactory results were obtained. The mechanism of the proposed reaction was also discussed.

  9. Fiber bundle based fluorescence tomography system for human breast imaging

    NASA Astrophysics Data System (ADS)

    Lin, Yuting; Nalcioglu, Orhan; Gulsen, Gultekin

    2009-07-01

    Fluorescence diffuse optical tomography (FT) is a promising molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. In this phantom study, we built a photo-multiplier tube (PMT) based single detection system that uses fiber bundles to collect light. Measurements were acquired both with a 1 mm diameter single fiber and a 6 mm diameter fiber bundle using the very same detection unit for comparison purposes. We demonstratethat the fluorescence concentration and lifetime can be well recovered for 6 mm diameter objects deeply embedded in an 80 mm diameter breast-sized phantom when the fiber bundle is utilized.

  10. Dynamic fluorescence lifetime imaging based on acousto-optic deflectors.

    PubMed

    Yan, Wei; Peng, Xiao; Qi, Jing; Gao, Jian; Fan, Shunping; Wang, Qi; Qu, Junle; Niu, Hanben

    2014-01-01

    We report a dynamic fluorescence lifetime imaging (D-FLIM) system that is based on a pair of acousto-optic deflectors for the random regions of interest (ROI) study in the sample. The two-dimensional acousto-optic deflector devices are used to rapidly scan the femtosecond excitation laser beam across the sample, providing specific random access to the ROI. Our experimental results using standard fluorescent dyes in live cancer cells demonstrate that the D-FLIM system can dynamically monitor the changing process of the microenvironment in the ROI in live biological samples. PMID:25375349

  11. Dendrimer based fluorescent glucose sensor for diabetic monitoring

    NASA Astrophysics Data System (ADS)

    Ibey, Bennett L.; Beier, Hope T.; Rounds, Rebecca M.; Pishko, Michael V.; Coté, Gerard L.

    2006-02-01

    Fluorescent glucose assays based on the affinity reaction between Concanavalin A and dextran have been extensively studied. However, advancements in polymer science have allowed for new macromolecules capable of replacing dextran which may improve the performance of this well-known assay. Dendrimer macromolecules, being highly ordered and spherical, allow for the binding of specific residues to the terminal (peripheral) binding sites, enabling researchers to customize the molecule. In this research, glycosylated dendrimers have been engineered to replace dextran to allow for more controlled chemical and fluorescent responses (eliminate multivalent binding and improve reversibility). This new assay has been shown to form small aggregate particles containing many Con A and glycosylated dendrimers resulting in a substantial loss in fluorescent intensity. Overall, this assay shows promise for use as part of an implantable glucose monitoring device, but more research needs to be done to increase sensor stability and optimize the sensor response to glucose.

  12. Fluorescent detection of ATP based on signaling DNA aptamer attached silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Yanyan; Wang, Yusong; Liu, Bin

    2008-10-01

    Novel methods for rapid, sensitive and low-cost biomolecule detection have attracted particular interest because of their wide use in medical diagnostics, food inspection and biomedical research applications. In this work, we report a simple and efficient silica nanoparticle (NP)-based fluorescent assay for ATP detection. It takes advantage of the washing and separation properties of NPs and the structure-switch property of DNA aptamers, resulting in fluorescence change of the supernatant in the presence of targets. A linear response for ATP detection was observed from 0 to 6 mM with a detection limit of ~34 µM. This detection strategy could be generalized to other aptamer-based detection systems.

  13. Highly selective and sensitive detection of mercuric ion based on a visual fluorescence method.

    PubMed

    Yuan, Chao; Zhang, Kui; Zhang, Zhongping; Wang, Suhua

    2012-11-20

    The instant and on-site detection of trace aqueous mercuric ion still remains a challenge for environmental monitoring and protection. This work demonstrates a new analytical method and its utility for visual detection of aqueous Hg(2+) on the basis of a novel water-soluble CdSe-ZnS quantum dots (QDs) functionalized with a bidentate ligand of 2-hydroxyethyldithiocarbamate (HDTC). The fluorescence of the aqueous HDTC modified QDs (HDTC-QDs) could be selectively and efficiently quenched by Hg(2+) through a surface chelating reaction between HDTC and Hg(2+), and the detection limit was measured to be 1 ppb. Most interestingly, the orange fluorescence of the HDTC-QDs gradually changes to red upon the increasing amount of Hg(2+) added besides the decreasing of the fluorescence intensity. By taking advantage of this optical phenomenon, a paper-based sensor for aqueous Hg(2+) detection has been developed by immobilizing the HDTC-QDs on cellulose acetate paper which has low background fluorescence in the wavelength range. The paper-based sensor showed high sensitivity and selectivity for Hg(2+) visual detection. When Hg(2+) was dropped onto the paper-sensor, an obviously distinguishable fluorescence color evolution (from orange to red) could be clearly observed depending on the concentration of Hg(2+). The limit of detection of the visual method for aqueous Hg(2+) detection was as low as 0.2 ppm. The very simple and effective strategy reported here should facilitate the development of portable and reliable fluorescence chemosensors for mercuric pollution control. PMID:23121315

  14. A Simple Sequence Repeat-Based Linkage Map of Barley

    Microsoft Academic Search

    L. Ramsay; M. Macaulay; K. MacLean; L. Cardle; J. Fuller; K. J. Edwards; S. Tuvesson; M. Morgante; A. Massari; E. Maestri; N. Marmiroli; T. Sjakste; M. Ganal; W. Powell; R. Waugh

    A total of 568 new simple sequence repeat (SSR)-based markers for barley have been developed from a combination of database sequences and small insert genomic libraries enriched for a range of short simple sequence repeats. Analysis of the SSRs on 16 barley cultivars revealed variable levels of informativeness but no obvious correlation was found with SSR repeat length, motif type,

  15. Simple and rapid preparation of red fluorescence and red color S. aureus derived nanobioparticles for pathogen detection.

    PubMed

    Hu, Wei; Zhang, Yun; Yang, Hang; Yu, Junping; Wei, Hongping

    2015-08-01

    In this study, a simple and rapid method was developed to transform protein A producing Staphylococcus aureus cells into red color and red fluorescent nanobioparticles, which were homogeneous, dispersive and relatively stable with a uniform size of 800nm. The method consists of reaction with a monotetrazolium redox dye at 25°C for 15min and heat inactivation at 65°C for 30min. This method provided the first S. aureus nanobioparticles with the dual property of red color and red fluorescence. Attributed to the IgG binding site known as protein A on their surface, the nanobioparticles could be used as vectors for immunoassays of many bacteria and viruses. Coagglutination test of Escherichia coli O157:H7 observed by naked eyes showed that the detection limitation of the nanobioprobes was 1?10(6)CFU/ml, which was about 100 times more sensitive than the natural uncolored S. aureus bioprobes. Red fluorescence detection and analysis of the coagglutination product by a microplate reader lowered the detection limit to 2.5?10(4)CFU/ml. PMID:26003440

  16. A peptide-based fluorescent chemosensor for multianalyte detection.

    PubMed

    Wang, Peng; Liu, Lixuan; Zhou, Panpan; Wu, Wenyu; Wu, Jiang; Liu, Weisheng; Tang, Yu

    2015-10-15

    A novel multifunctional peptide fluorescent chemosensor (DP-3) with a lysine backbone and double sides conjugated with histidine and dansyl groups has been designed and synthesized by solid phase synthesis. This chemosensor is a promising analytical tool for detecting Zn(2+), Cu(2+), and S(2-) based on different mechanisms in 100% aqueous solutions, and intracellular biosensing has been successfully actualized. The peptide beacon structure of DP-3 makes it more stable and capable of achieving multianalyte detection, especially for sulfide ions. Until now, there have been few examples of using a peptide fluorescent chemosensor to detect anions with a continuous method. As designed, DP-3 exhibits excellent cell permeation and low biotoxicity and displays high selectivity and sensitivity, with Zn(2+) and Cu(2+) detection limits of 82nM and 78nM, respectively. This study raises the new possibility of a highly selective peptide fluorescent chemosensor for multifunctional detection, including cation and anions, by different mechanisms in environmental and biological systems. We expect that this work will inspire the development of a multifunctional beacon peptide-based fluorescent chemosensor library using modifiable lateral and terminal groups for a variety of practical applications in physiological and pathological events. PMID:25957834

  17. Neurotransmitter imaging in living cells based on native fluorescence detection

    SciTech Connect

    Tan, W.; Yeung, E.S. [Ames Lab., IA (United States)]|[Iowa State Univ., Ames, IA (United States); Parpura, V.; Haydon, P.G. [Iowa State Univ., Ames, IA (United States)

    1995-08-01

    A UV laser-based optical microscope and CCD detection system with high sensitivity has been developed to image neurotransmitters in living cells. We demonstrate the detection of serotonin that has been taken up into individual living glial cells (astrocytes) based on its native fluorescence. We found that the fluorescence intensity of astrocytes increased by up to 10 times after serotonin uptake. The temporal resolution of this detection system at 10{sup -4} M serotonin is as fast as 50 ms, and the spatial resolution is diffraction limited. This UV laser microscope imaging system shows promise for studies of spatial-temporal dynamics of neurotransmitter levels in living neurons and glia. 19 refs., 5 figs., 1 tab.

  18. Fluorescence based optical fibre fire alarm system [for aeroengine application

    Microsoft Academic Search

    T. Sun; K. T. V. Grattan; W. M. Sun

    2002-01-01

    A fluorescence-based optical fibre fire alarm system, which offers the advantages of light weight and relatively low cost, has been discussed to address the specifications required for aeroengine fire detection. A temperature excursion as low as 50-100°C has been detected and current spatial resolution achieved is ?20 cm. Lengths of 1.2 m of Er & Tm doped fibres have been

  19. A fluorescence enhancement-based sensor for hydrogen sulfate ion.

    PubMed

    Yang, Shih-Tse; Liao, De-Jhong; Chen, Shau-Jiun; Hu, Ching-Han; Wu, An-Tai

    2012-04-01

    Sugar-aza-crown ether-based cavitand 1 can act as a selective turn-on fluorescence sensor for hydrogen sulfate ion in methanol among a series of tested anions. Spectroscopic studies, particularly NMR spectroscopy, revealed that the C-H hydrogen bonding between 1,2,3-triazole ring of cavitand 1 and hydrogen sulfate ion is crucial for the high selectivity of the receptor for hydrogen sulfate. PMID:22363932

  20. Wide and scalable field-of-view Talbot-grid-based fluorescence microscopy.

    PubMed

    Pang, Shuo; Han, Chao; Kato, Mihoko; Sternberg, Paul W; Yang, Changhuei

    2012-12-01

    Here we report a low-cost and simple wide field-of-view (FOV) on-chip fluorescence-imaging platform, termed fluorescence Talbot microscopy (FTM), which utilizes the Talbot self-imaging effect to enable efficient fluorescence imaging over a large and directly scalable FOV. The FTM prototype has a resolution of 1.2 ?m and an FOV of 3.9 mm × 3.5 mm. We demonstrate the imaging capability of FTM on fluorescently labeled breast cancer cells (SK-BR-3) and human embryonic kidney 293 (HEK) cells expressing green fluorescent protein. PMID:23202123

  1. Wide and scalable field-of-view Talbot-grid-based fluorescence microscopy

    PubMed Central

    Pang, Shuo; Han, Chao; Kato, Mihoko; Sternberg, Paul W.; Yang, Changhuei

    2013-01-01

    Here we report a low-cost and simple wide field-of-view (FOV) on-chip fluorescence-imaging platform, termed fluorescence Talbot microscopy (FTM), which utilizes the Talbot self-imaging effect to enable efficient fluorescence imaging over a large and directly scalable FOV. The FTM prototype has a resolution of 1.2 ?m and an FOV of 3.9 mm × 3.5 mm. We demonstrate the imaging capability of FTM on fluorescently labeled breast cancer cells (SK-BR-3) and human embryonic kidney 293 (HEK) cells expressing green fluorescent protein. PMID:23202123

  2. A Simple Visualization of Double Bond Properties: Chemical Reactivity and UV Fluorescence

    ERIC Educational Resources Information Center

    Grayson, Scott M.

    2012-01-01

    A simple, easily visualized thin-layer chromatography (TLC) staining experiment is presented that highlights the difference in reactivity between aromatic double bonds and nonaromatic double bonds. Although the stability of aromatic systems is a major theme in organic chemistry, the concept is rarely reinforced "visually" in the undergraduate…

  3. Cellular discrimination based on spectral analysis of instrinic fluorescence

    NASA Astrophysics Data System (ADS)

    Goddard, G. R.; Houston, J. P.; Martin, J. C.; Graves, S. W.; Freyer, J. P.

    2008-02-01

    The increasing need for highly polychromatic approaches to flow cytometry, coupled with rapid technological advances, have driven the design and implementation of commercial instruments that measure up to 19 parameters using multiple lasers for excitation, an intricate optical filter/mirror arrangement, and analysis using fluorescence compensation approaches. Although such conventional multiparameter flow cytometers have proven highly successful, there are several types of analytical measurements that would benefit from higher density of spectral information and a more flexible approach to spectral analysis including, but certainly not limited to: spectral deconvolution of overlapping spectra, fluorescence resonance energy transfer measurements, metachromic dye analysis, cellular autofluorescence characterization, and flow based Raman spectroscopy. For these purposes, we have developed a high resolution spectral flow cytometer using an EMCCD camera with 1600 by 200 pixels, which is capable of detecting less than 200 fluorescein molecules with a spectral resolution of less than 3 nm. This instrument will enable high throughput characterization of single cell or particle emission spectra. For proof of principle instrument operation, we have begun characterization of intrinsic cellular autofluorescence, which is the major source of background for cell-based fluorescence assays. Specifically, we will describe recent work on the high resolution spectral characterization of autofluorescence for several commonly used cell types. Autofluorescence emission is known to cover over almost the entire spectrum from 300 to nearly 800 nm. These emissions are attributed to flavins, elastin, Indolamine dimers and trimers, NADH and collagen among other molecules. We will show that several unique autofluorescence spectra arise in the different cell lines thereby suggesting the possibility of discrimination of cell types based on intrinsic fluorescence.

  4. Simple method to enhance the photostability of the fluorescence reporter R6G for prolonged single-molecule studies.

    PubMed

    Guo, Lin; Gai, Feng

    2013-07-25

    For fluorescence-based single-molecule studies, photobleaching of the dye reporter often limits the time window over which individual molecules can be followed. As such, many strategies, for example, using a cocktail of chemical reagents, have been developed to decrease the rate of photobleaching. Herein, we introduce a new and highly effective method to enhance the photostability of one of the commonly used fluorescent dyes, rhodamine 6G (R6G). We show that micrometer-sized polydimethylsiloxane (PDMS) wells, when the PDMS surface is properly treated, not only provide a confined environment for single-molecule detection but can also significantly increase the survival time of individual R6G molecules before photobleaching. Moreover, our results suggest, consistent with several previous studies, that R6G photobleaching involves a radical state. PMID:23641719

  5. Highly efficient blue electroluminescence based on thermally activated delayed fluorescence

    NASA Astrophysics Data System (ADS)

    Hirata, Shuzo; Sakai, Yumi; Masui, Kensuke; Tanaka, Hiroyuki; Lee, Sae Youn; Nomura, Hiroko; Nakamura, Nozomi; Yasumatsu, Mao; Nakanotani, Hajime; Zhang, Qisheng; Shizu, Katsuyuki; Miyazaki, Hiroshi; Adachi, Chihaya

    2015-03-01

    Organic compounds that exhibit highly efficient, stable blue emission are required to realize inexpensive organic light-emitting diodes for future displays and lighting applications. Here, we define the design rules for increasing the electroluminescence efficiency of blue-emitting organic molecules that exhibit thermally activated delayed fluorescence. We show that a large delocalization of the highest occupied molecular orbital and lowest unoccupied molecular orbital in these charge-transfer compounds enhances the rate of radiative decay considerably by inducing a large oscillator strength even when there is a small overlap between the two wavefunctions. A compound based on our design principles exhibited a high rate of fluorescence decay and efficient up-conversion of triplet excitons into singlet excited states, leading to both photoluminescence and internal electroluminescence quantum yields of nearly 100%.

  6. Monitoring methionine sulfoxide with stereospecific mechanism-based fluorescent sensors.

    PubMed

    Tarrago, Lionel; Péterfi, Zalán; Lee, Byung Cheon; Michel, Thomas; Gladyshev, Vadim N

    2015-05-01

    Methionine can be reversibly oxidized to methionine sulfoxide (MetO) under physiological and pathophysiological conditions, but its use as a redox marker suffers from the lack of tools to detect and quantify MetO within cells. In this work, we created a pair of complementary stereospecific genetically encoded mechanism-based ratiometric fluorescent sensors of MetO by inserting a circularly permuted yellow fluorescent protein between yeast methionine sulfoxide reductases and thioredoxins. The two sensors, respectively named MetSOx and MetROx for their ability to detect S and R forms of MetO, were used for targeted analysis of protein oxidation, regulation and repair as well as for monitoring MetO in bacterial and mammalian cells, analyzing compartment-specific changes in MetO and examining responses to physiological stimuli. PMID:25799144

  7. An Information Retrieval Model Based on Simple Bayesian Networks

    E-print Network

    de Campos, Luis M.

    Information retrieval (IR) is a subfield of computer science that deals with the automated storageAn Information Retrieval Model Based on Simple Bayesian Networks Silvia Acid,1,* Luis M. de Campos information retrieval (IR) model, based on Bayesian networks (BNs), is proposed. We first consider a basic

  8. A Simple Multiple Variance-Ratio Test Based G. Colletaz

    E-print Network

    Boyer, Edmond

    A Simple Multiple Variance-Ratio Test Based on Ranks G. Colletaz Laboratoire d'Economie d.colletaz@univ-orleans.fr Abstract Using Chow and Denning's arguments applied to the individual hypothesis test methodology of Wright (2000) I propose a multiple variance-ratio test based on ranks to investigate the hypothesis

  9. Seminaphthofluorescein-Based Fluorescent Probes for Imaging Nitric Oxide in Live Cells

    E-print Network

    Pluth, Michael D.

    Fluorescent turn-on probes for nitric oxide based on seminaphthofluorescein scaffolds were prepared and spectroscopically characterized. The Cu(II) complexes of these fluorescent probes react with NO under anaerobic ...

  10. A colorimetric and turn-on fluorescent chemosensor for Al(III) based on a chromone Schiff-base

    NASA Astrophysics Data System (ADS)

    Fan, Long; Li, Tian-rong; Wang, Bao-dui; Yang, Zheng-yin; Liu, Chun-jiao

    2014-01-01

    A simple Schiff-base receptor 7-methoxychromone-3-carbaldehyde-(pyridylformyl) hydrazone (MCNH) was prepared. It exhibits an “off-on-type” mode with high sensitivity in the presence of Al3+. This compound could be used as Al3+ probe in ethanol and it features visible light excitation (433 nm) and emission (503 nm) profiles. Upon binding of Al3+, a significant fluorescence enhancement with a turn-on ratio over 800-fold was triggered. However, other metal ions had no such significant effect on the fluorescence. MCNH can also be used as a colorimetric chemosensor for Al3+, which is easily observed from colorless to yellow-green by the naked-eye. The detection limit of MCNH for Al3+ was as low as 1.9 × 10-7 M.

  11. A simple and rapid fluorescence in situ hybridization microwave protocol for reliable dicentric chromosome analysis

    PubMed Central

    Cartwright, Ian M.; Genet, Matthew D.; Kato, Takamitsu A.

    2013-01-01

    Fluorescence in situhybridization (FISH) is an extremely effective and sensitive approach to analyzing chromosome aberrations. Until recently, this procedure has taken multiple days to complete. The introduction of telomeric and centromeric peptide nucleic acid (PNA) probes has reduced the procedure's duration to several hours, but the protocols still call for a high temperature (80–90°C) step followed by 1–3 h of hybridization. The newest method to speed up the FISH protocol is the use of a microwave to shorten the heating element to less than a minute; however this protocol still calls for a 1-h hybridization period. We have utilized PNA centromere/telomere probes in conjunction with a microwave oven to show telomere and centromere staining in as little as 30 s. We have optimized the hybridization conditions to increase the sensitivity and effectiveness of the new protocol and can effectively stain chromosomes in 2 min and 30 s of incubation. We have found that our new approach to FISH produces extremely clear and distinct signals. Radiation-induced dicentric formation in mouse and human fibroblast cells was analyzed by two individual scorers and the observed dicentrics matched very well. PMID:23161278

  12. Effects of Mechanical Constraint on the Performance of Fluorescent Hydrogel-based Fiber Optic Sensors

    NASA Astrophysics Data System (ADS)

    Jukl, Jennifer Marie

    Although biosensor technology is a broad and well-studied field, the progress of many novel sensor technologies faces challenges. These challenges range from simple design considerations to fundamental issues with the concept or approach. One of the most active fields of sensor research integrates fiber optics with specially engineered fluorescent molecules. This type of sensor typically utilizes a porous polymer or porous glass substrate to entrap the fluorescent (or fluorescently-tagged) molecule. Porous polymer hydrogels are generally favored due to their ease of fabrication, low cost, adaptability, and biocompatibility. While hydrogels are ideal for both functional molecule suspension and fluid diffusion, their porosity and hydrophilicity are not always advantageous. The largest drawback of these properties is the hydrogel swelling they produce and the resulting geometric changes. This project investigated the limitations of fluorescent hydrogel-based sensors and the effects of unpredictable structural changes hydrogels undergo during typical, unrestrained swelling. The significance of covalent incorporation of the sensing fluorophore into the hydrogel matrix is also explored. Leaching tests were conducted using polyacrylamide (PAm) hydrogels which were impregnated with one of two pH sensitive fluorophores, one which bonded covalently with the hydrogel matrix during polymerization (fluorescein o-acrylate), and one which did not (fluorescein sodium). Once determined to be effective, the covalently bonding fluorophore was used to create constrained-dimension fluorescent pH sensors. These sensors were tested for effectiveness and reproducibility. All data was collected using a laboratory grade optical fibers, a USB spectrometer, and SpectraSuite software (Ocean Optics, 2010) unless otherwise specified.

  13. Photon upconversion in homogeneous fluorescence-based bioanalytical assays.

    PubMed

    Soukka, Tero; Rantanen, Terhi; Kuningas, Katri

    2008-01-01

    Upconverting phosphors (UCPs) are very attractive reporters for fluorescence resonance energy transfer (FRET)-based bioanalytical assays. The large anti-Stokes shift and capability to convert near-infrared to visible light via sequential absorption of multiple photons enable complete elimination of autofluorescence, which commonly impairs the performance of fluorescence-based assays. UCPs are ideal donors for FRET, because their very narrow-banded emission allows measurement of the sensitized acceptor emission, in principle, without any crosstalk from the donor emission at a wavelength just tens of nanometers from the emission peak of the donor. In addition, acceptor dyes emitting at visible wavelengths are essentially not excited by near-infrared, which further emphasizes the unique potential of upconversion FRET (UC-FRET). These characteristics result in favorable assay performance using detection instrumentation based on epifluorometer configuration and laser diode excitation. Although UC-FRET is a recently emerged technology, it has already been applied in both immunoassays and nucleic acid hybridization assays. The technology is also compatible with optically difficult biological samples, such as whole blood. Significant advances in assay performance are expected using upconverting lanthanide-doped nanocrystals, which are currently under extensive research. UC-FRET, similarly to other fluorescence techniques based on resonance energy transfer, is strongly distance dependent and may have limited applicability, for example in sandwich-type assays for large biomolecules, such as viruses. In this article, we summarize the essentials of UC-FRET, describe its current applications, and outline the expectations for its future potential. PMID:18596348

  14. CINCH (confocal incoherent correlation holography) super resolution fluorescence microscopy based upon FINCH (Fresnel incoherent correlation holography)

    NASA Astrophysics Data System (ADS)

    Siegel, Nisan; Storrie, Brian; Bruce, Marc; Brooker, Gary

    2015-03-01

    FINCH holographic fluorescence microscopy creates high resolution super-resolved images with enhanced depth of focus. The simple addition of a real-time Nipkow disk confocal image scanner in a conjugate plane of this incoherent holographic system is shown to reduce the depth of focus, and the combination of both techniques provides a simple way to enhance the axial resolution of FINCH in a combined method called "CINCH". An important feature of the combined system allows for the simultaneous real-time image capture of widefield and holographic images or confocal and confocal holographic images for ready comparison of each method on the exact same field of view. Additional GPU based complex deconvolution processing of the images further enhances resolution.

  15. Frequency-domain fluorescence based fiber optic fire alarm system

    NASA Astrophysics Data System (ADS)

    Sun, T.; Zhang, Z. Y.; Grattan, K. T. V.

    2001-04-01

    Erbium and thulium doped fibers have been investigated in this work, for the first time, to determine their potential in fire or high temperature alarm applications based on the use of fluorescence decay in the frequency domain. Two configurations of the sensing system have been tested and compared, with particular reference to their minimum spatial resolution and location discrimination characteristics. The initial results show that temperature excursions of 125 °C within 10 cm along a length of a 1.2 m sensing loop can be determined within a period of some tens of seconds, which is adequate for the sensor purpose, and work is continuing to increase the system's sensitivity.

  16. A Simple Inquiry-Based Lab for Teaching Osmosis

    ERIC Educational Resources Information Center

    Taylor, John R.

    2014-01-01

    This simple inquiry-based lab was designed to teach the principle of osmosis while also providing an experience for students to use the skills and practices commonly found in science. Students first design their own experiment using very basic equipment and supplies, which generally results in mixed, but mostly poor, outcomes. Classroom "talk…

  17. A simple routing protocol for PLC-based AMR systems

    Microsoft Academic Search

    B. Sivaneasan; P. L. So; E. Gunawan

    2009-01-01

    A new, simple and effective communication protocol is developed and evaluated for implementation in power line communication (PLC) based automatic meter reading (AMR) systems. The protocol involves request broadcasting by the data concentrator (DC) and subsequent re-broadcasting by lower level meters up till the third hop using a novel dual purpose packet for transmission. The proposed routing protocol employs CSMA-CA

  18. Implementing Orthogonal Persistence: A Simple Optimization Based on Replicating Collection

    E-print Network

    Gifford, David K.

    Implementing Orthogonal Persistence: A Simple Optimization Based on Replicating Collection Scott), U. S. Air Force, Wright­Patterson AFB, OH 45433­ 6543 under Contract F33615­90­C­1465, Arpa Order No. 7597, by the Air Force Systems Command and the Defense Advanced Research Projects Agency (DARPA) under

  19. Implementing Orthogonal Persistence: A Simple Optimization Based on Replicating Collection

    E-print Network

    Williams, Brian C.

    Implementing Orthogonal Persistence: A Simple Optimization Based on Replicating Collection Scott by the Avionics Lab, Wright Re- search and DevelopmentCenter, AeronauticalSystemsDivision AFSC, U. S. Air Force, Wright-Patterson AFB, OH 45433- 6543 under Contract F33615-90-C-1465, Arpa Order No. 7597, by the Air

  20. A finite-element-based reconstruction method for 3D fluorescence tomography

    E-print Network

    Virginia Tech

    . Bouman, Q. Zhang, D. A. Boas, and R. P. Milane, "Fluorescence optical diffusion tomography," Appl. Opt-Muraca, "Adaptive finite element based tomog- raphy for fluorescence optical imaging in tissue," Opt. Express 12, and X. Intes, "Time domain fluorescent diffuse optical tomography: analytical expressions," Opt. Express

  1. mb-FLIM: Model-based fluorescence lifetime imaging Qiaole Zhaoa

    E-print Network

    Stallinga, Sjoerd

    mb-FLIM: Model-based fluorescence lifetime imaging Qiaole Zhaoa , Ian Ted Young*a , Raymond to estimate fluorescence lifetimes. Multiple frequencies are present in the excitation signal. Modeling the entire fluorescence and measurement process produces an analytical ratio of polynomials in the lifetime

  2. A fluorescence lifetime-based assay for serine and threonine kinases that is suitable for high-throughput screening.

    PubMed

    Paterson, Michael J; Dunsmore, Colin J; Hurteaux, Reynald; Maltman, Beatrice A; Cotton, Graham J; Gray, Alexander

    2010-07-01

    We describe the development of a novel method for the assay of serine/threonine protein kinases based on fluorescence lifetime. The assay consists of three generic peptides (which have been used by others in the assay of >140 protein kinases in various assay formats) labeled with a long lifetime fluorescent dye (14 or 17 ns) that act as substrates for protein kinases and an iron(III) chelate that modulates the fluorescence lifetime of the peptide only when it is phosphorylated. The decrease in average fluorescence lifetime as measured in a recently developed fluorescence lifetime plate reader (Edinburgh Instruments) is a measure of the degree of phosphorylation of the peptide. We present data showing that the assay performs as well as, and in some cases better than, the "gold standard" radiometric kinase assays with respect to Z' values, demonstrating its utility in high-throughput screening applications. We also show that the assay gives nearly identical results in trial screening to those obtained by radiometric assays and that it is less prone to interference than simple fluorescence intensity measurements. PMID:20230774

  3. Fluorescent sensing of pyrophosphate anion in synovial fluid based on DNA-attached magnetic nanoparticles.

    PubMed

    Tong, Li-Li; Chen, Zhen-Zhen; Jiang, Zhong-Yao; Sun, Miao-Miao; Li, Lu; Liu, Ju; Tang, Bo

    2015-10-15

    In this work, a new fluorescent method for sensitive detection of pyrophosphate anion (P2O7(4-), PPi) in the synovial fluid was developed using fluorophore labeled single-stranded DNA-attached Fe3O4 NPs. The sensing approach is based on the strong affinity of PPi to Fe3O4 NPs and highly efficient fluorescent quenching ability of Fe3O4 NPs for fluorophore labeled single-stranded DNA. In the presence of PPi, the fluorescence would enhance dramatically due to desorption of fluorophore labeled single-stranded DNA from the surface of Fe3O4 NPs, which allowed the analysis of PPi in a very simple manner. The proposed sensing system allows for the sensitive determination of PPi in the range of 2.0×10(-7)-4×10(-6)M with a detection limit of 76nM. Importantly, the protocol exhibits excellent selectivity for the determination of PPi over other phosphate-containing compounds. The method was successfully applied to the determination of PPi in the synovial fluid, which suggests our proposed method has great potential for diagnostic purposes. PMID:25957830

  4. Monitoring water supplies for weaponized bacteria and bacterial toxins using rapid fluorescence-based viability and affinity assays

    NASA Astrophysics Data System (ADS)

    Van Tassell, Roger L.; Evans, Mishell

    2004-03-01

    The rapid detection of weaponized bacteria and toxins is a major problem during a biological attack. Although sensitive detection formats exist for many biowarfare agents, they often require advanced training and complex procedures. Luna has developed simple, rapid means for determining the presence of pathogens and bacterial toxins in water supplies using fluorescence-based assays that can be adapted for field use. The batteries of rapid assays are designed for i) determining cell viability and bacterial loads by exploiting metabolic markers (e.g., acid-production, redox potentials, etc) and ii) detecting bacterial toxins using fluorescent, polymerized affinity liposomes (fluorosomes). The viability assays were characterized using E. coli, S. aureus and the anthrax simulant, B. globigii. The viability assays detected bacterial loads of ~ 104 CFU/ml and with simple filtration ~ 100CFU/ml could be detected. The affinity fluorosomes were characterized using cholera toxin (CT). Affinity liposomes displaying GM1 and anti-CT antibodies could detect CT at fluorescence system, Luna characterized the binding of affinity fluorosomes to respective targets and determined the responses of bacterial loads in the fluorescent viability assays. Using this two-tiered approach, Luna demonstrated that water susceptible to sabotage could be easily monitored and confirmed for specific agents using simple, general and specific fluorescence-based detection schemes based on metabolism and ligand-target interactions.

  5. A carbon nanotubes based fluorescent aptasensor for highly sensitive detection of adenosine deaminase activity and inhibitor screening in natural extracts.

    PubMed

    Hu, Kun; Huang, Yong; Wang, Sheng'e; Zhao, Shulin

    2014-07-01

    A carbon nanotubes (CNTs) based fluorescent aptasensor was developed for adenosine deaminase (ADA) activity detection and inhibitor screening by using adenosine (AD) as the substrate. This sensing system consists of CNTs, AD, split anti-AD aptamer fragment and dye-labeled aptamer fragment. In the absence of ADA, two aptamer fragments bind simultaneously with AD to form an AD-aptamer complex. This AD-aptamer complex cannot adsorb onto CNTs, and has high fluorescence intensity. When ADA is introduced into this system, ADA can convert AD into inosine, which has not affinity to the split anti-AD aptamer fragment. Thus, the split anti-AD aptamer fragments were adsorbed onto CNTs via strong ?-? stacking interactions, resulting in the quenching of the fluorescence of the dye-labeled aptamer fragment. The proposed aptasensor can detect ADA activity from 0.005 to 0.2U/mL with a low detection limit of 0.002 U/mL. Moreover, it has been also demonstrated that this CNTs-based fluorescence aptasensor is suitable for ADA inhibitor screening from traditional Chinese medicine (TCM). Considering the superior sensitivity and specificity, the proposed CNTs-based fluorescent aptasensor can be expected to provide a simple, cost-effective and sensitive platform for the detection of ADA activity and screening of potential drugs. PMID:24682016

  6. Fluorescent switch for fast and selective detection of mercury (II) ions in vitro and in living cells and a simple device for its removal.

    PubMed

    Yuan, Yue; Jiang, Shenlong; Miao, Qingqing; Zhang, Jia; Wang, Mengjing; An, Linna; Cao, Qinjingwen; Guan, Yafeng; Zhang, Qun; Liang, Gaolin

    2014-07-01

    A water-soluble, biocompatible, and fluorescent chemosensor (1) for label-free, simple, and fast detection of mercury ions (Hg(2+)) in aqueous solutions and in HepG2 cells with high selectivity is reported herein. Chelation of 1 with Hg(2+) results in the disappearance of its fluorescence emission at 350 nm and the appearance of a new emission at 405 nm. Selectivity and interference studies indicated that 1 could be selectively chelated by Hg(2+) without interference from other metal ions. Insight into the mechanisms responsible for its fluorescence effect was gained from ultrafast transient absorption spectroscopy. With these properties, 1 was successfully applied for imaging Hg(2+) in living cells and for removing Hg(2+) from river water. Moreover, we also constructed a simple device for fast and effective removal of Hg(2+) from contaminated liquid samples. PMID:24840434

  7. Design of fluorescent assays for cyanide and hydrogen peroxide based on the inner filter effect of metal nanoparticles.

    PubMed

    Shang, Li; Dong, Shaojun

    2009-02-15

    We have demonstrated the design of a new type fluorescent assay based on the inner filter effect (IFE) of metal nanoparticles (NPs), which is conceptually different from the previously reported metal NPs-based fluorescent assays. With a high extinction coefficient and tunable plasmon absorption feature, metal NPs are expected to be capable of functioning as a powerful absorber to tune the emission of the fluorophore in the IFE-based fluorescent assays. In this work, we presented two proof-of-concept examples based on the IFE of Au NPs by choosing MDMO-PPV as a model fluorophore, whose fluorescence could be tuned by the absorbance of Au NPs with a much higher sensitivity than the corresponding absorbance approach. While the first assay worked in a turn-on mode upon the etching of Au NPs by the analyte, CN(-), the second one functioned in a turn-off mode upon the catalytic growth of Au NPs by the analyte, H(2)O(2). As a result, the present IFE-based approach can detect cyanide ranging from 1.0 x 10(-6) to 6.0 x 10(-4) M with a detection limit of 6.0 x 10(-7) M and H(2)O(2) ranging from 1.5 x 10(-7) to 2.2 x 10(-5) M with a detection limit of 8.5 x 10(-8) M, respectively. Notably, the present IFE-based approach allows the design of fluorescent assays in a more simple, time-saving, and economical approach when compared with conventional metal NPs-based fluorescent assays, since no modification step of the fluorophore was needed any more. PMID:19140677

  8. Simple and Rapid Quality Control of Sulfated Glycans by a Fluorescence Sensor Assay—Exemplarily Developed for the Sulfated Polysaccharides from Red Algae Delesseria sanguinea

    PubMed Central

    Lühn, Susanne; Grimm, Juliane C.; Alban, Susanne

    2014-01-01

    Sulfated polysaccharides (SP) from algae are of great interest due to their manifold biological activities. Obstacles to commercial (especially medical) application include considerable variability and complex chemical composition making the analysis and the quality control challenging. The aim of this study was to evaluate a simple microplate assay for screening the quality of SP. It is based on the fluorescence intensity (FI) increase of the sensor molecule Polymer-H by SP and was originally developed for direct quantification of SP. Exemplarily, 65 SP batches isolated from the red alga Delesseria sanguinea (D.s.-SP) and several other algae polysaccharides were investigated. Their FI increase in the Polymer-H assay was compared with other analytical parameters. By testing just one concentration of a D.s.-SP sample, quality deviations from the reference D.s.-SP and thus both batch-to-batch variability and stability can be detected. Further, structurally distinct SP showed to differ in their concentration-dependent FI profiles. By using corresponding reference compounds, the Polymer-H assay is therefore applicable as identification assay with high negative predictability. In conclusion, the Polymer-H assay showed to represent not only a simple method for quantification, but also for characterization identification and differentiation of SP of marine origin. PMID:24727392

  9. Simple and rapid quantification of gadolinium in urine and blood plasma samples by means of total reflection X-ray fluorescence (TXRF).

    PubMed

    Telgmann, Lena; Holtkamp, Michael; Künnemeyer, Jens; Gelhard, Carsten; Hartmann, Marcel; Klose, Annika; Sperling, Michael; Karst, Uwe

    2011-10-01

    A simple and rapid method to determine gadolinium (Gd) concentrations in urine and blood plasma samples by means of total reflection X-ray fluorescence (TXRF) was developed. With a limit of detection (LOD) of 100 ?g L(-1) in urine and 80 ?g L(-1) in blood plasma and a limit of quantification (LOQ) of 330 ?g L(-1) in urine and 270 ?g L(-1) in blood plasma, it allows analyzing urine samples taken from magnetic resonance imaging (MRI) patients during a period of up to 20 hours after the administration of Gd-based MRI contrast agents by means of TXRF. By parallel determination of the urinary creatinine concentration, it was possible to monitor the excretion kinetics of Gd from the patient's body. The Gd concentration in blood plasma samples, taken immediately after an MRI examination, could be determined after rapid and easy sample preparation by centrifugation. All measurements were validated with inductively coupled plasma mass spectrometry (ICP-MS). TXRF is considered to be an attractive alternative for fast and simple Gd analysis in human body fluids during daily routine in clinical laboratories. PMID:21847492

  10. Development of an image processing support system based on fluorescent dye to prevent elderly people with dementia from wandering.

    PubMed

    Nishigaki, Yutaka; Tanaka, Kentaro; Kim, Juhyon; Nakajima, Kazuki

    2013-01-01

    The wandering of elderly people with dementia is a significant behavioral problem and is a heavy burden on caregivers in residential and nursing homes. Thus, warning systems have been developed to prevent elderly people with dementia from leaving the premises. Some of these systems use radio waves. However, systems based on radio waves present several practical problems. For instance, the transmitter must be carried and may become lost; in addition, the battery of the transmitter must be changed. To solve these problems, we developed a support system that prevents elderly people with dementia from wandering. The system employs image processing technology based on fluorescent dye. The composition of the support system can be described as follows: fluorescent dye is painted in a simple shape on the clothes of an elderly person. The fluorescent color becomes visible by irradiation with a long wavelength of ultraviolet light. In the present paper, the relationship between the color of the dye and the cloth was investigated. A 3D video camera was used to acquire a 3D image and detect the simple shape. As a preliminary experiment, 3 colors (red, green and blue) of fluorescent dye were applied to cloths of 9 different colors. All fluorescent colors were detected on 6 of the cloths, but red and blue dye could not be detected on the other 3 cloths. In contrast, green dye was detectable on all 9 of the cloths. Additionally, we determined whether green dye could be detected in an actual environment. A rectangular shaped patch of green fluorescent dye was painted on the shoulder area of a subject, from the scapula to the clavicle. As a result, the green dye was detected on all 9 different colored cloths. PMID:24111431

  11. A sensitive biosensor with a DNAzyme for lead(ii) detection based on fluorescence turn-on.

    PubMed

    Guo, Yang; Li, Junting; Zhang, Xiaoqian; Tang, Yanli

    2015-06-15

    In this paper, we described a new DNAzyme-based fluorescent biosensor for the detection of Pb(2+). In the biosensor, the bulged structure is formed between the substrate labeled with fluorescein amidite (FAM) and DNAzyme after being annealed. Ethidium bromide (EB), the DNA intercalator, then intercalates into the double-stranded DNA section. Once FAM is excited, the FRET takes place from FAM to EB, which leads to the fluorescence of FAM decreasing greatly. In the presence of Pb(2+), the substrate is cleaved by DNAzyme, which breaks the bulged structure. Then EB is released and the FRET from FAM to EB is inhibited. In this case, the fluorescence of FAM increases dramatically. Thus, the Pb(2+) ions can be detected by measuring the fluorescence enhancement of FAM. Under optimal conditions, the increased fluorescence intensity ratio of FAM is dependent on the lead level in the sample, and exhibits a linear response over a Pb(2+) concentration range of 0-100 nM with a detection limit of 530 pM. The sensor showed high selectivity in the presence of a number of interference ions. The river water samples were also tested with satisfying results by using the new method. This sensor is highly sensitive and simple without any additional treatments, which provides a platform for other biosensors based on DNAzyme. PMID:25978496

  12. CuInS2 quantum dots-based fluorescence turn off/on probe for detection of melamine.

    PubMed

    Liu, Siyu; Hu, Junjie; Zhang, Hao; Su, Xingguang

    2012-11-15

    In this paper, a sensitive and simple method for the determination of melamine (MA) was developed based on the fluorescence changes of the water-soluble CuInS(2) quantum dots (QDs). The water-soluble CuInS(2) QDs capped by mercaptopropionic acid (MPA) was directly synthesized by hydrothermal method based on our previous report. The fluorescence emission of CuInS(2) QDs was quenched by the oxidation of the surface of the QDs with H(2)O(2), and the quenched fluorescence of CuInS(2) QDs could be recovered upon the addition of small amounts of MA, which might be due to the surface passivation of the CuInS(2) QDs by MA. The other amino acids such as glycine and lysine had no effect on the quenched fluorescence of CuInS(2) QDs. Under optimum conditions, there was a good linear relationship between the fluorescence intensity of CuInS(2) QDs and the concentration range of MA from 1.0×10(-8) to 1.0×10(-5) mol/L with a detection limit as low as 5 nM. The proposed method was successfully applied to detect trace MA in raw milk with satisfactory results. Compared with previous reports, the proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation. PMID:23158336

  13. Simple structured hybrid WOLEDs based on incomplete energy transfer mechanism: from blue exciplex to orange dopant

    PubMed Central

    Zhang, Tianyou; Zhao, Bo; Chu, Bei; Li, Wenlian; Su, Zisheng; Yan, Xingwu; Liu, Chengyuan; Wu, Hairuo; Gao, Yuan; Jin, Fangming; Hou, Fuhua

    2015-01-01

    Exciplex is well known as a charge transfer state formed between electron-donating and electron-accepting molecules. However, exciplex based organic light emitting diodes (OLED) often performed low efficiencies relative to pure phosphorescent OLED and could hardly be used to construct white OLED (WOLED). In this work, a new mechanism is developed to realize efficient WOLED with extremely simple structure by redistributing the energy of triplet exciplex to both singlet exciplex and the orange dopant. The micro process of energy transfer could be directly examined by detailed photoluminescence decay measurement and time resolved photoluminescence analysis. This strategy overcomes the low reverse intersystem crossing efficiency of blue exciplex and complicated device structure of traditional WOLED, enables us to achieve efficient hybrid WOLEDs. Based on this mechanism, we have successfully constructed both exciplex-fluorescence and exciplex-phosphorescence hybrid WOLEDs with remarkable efficiencies. PMID:25975371

  14. Measurement of plasma volume using fluorescent silica-based nanoparticles

    PubMed Central

    Eisner, Christoph; Ow, Hooisweng; Yang, Tianxin; Jia, Zhanjun; Dimitriadis, Emilios; Li, Lingli; Wang, Kenneth; Briggs, Josephine; Levine, Mark; Schnermann, Jurgen

    2012-01-01

    Plasma volume (PV) is an important determinant of cardiovascular function and organ perfusion, and it is the target of infusion and diuretic therapies in daily clinical practice. Despite its fundamental importance PV is not commonly measured because available methods of tracer dilution are reliant on dye substances that suffer from numerous drawbacks including binding plasma proteins, spectral changes, and clearance kinetics that complicate analysis and interpretation. To address these issues, we have tested the utility of fluorescent nanoparticles comprised of a dye-rich silica core and polyethylene glycol-coated shell. Photophysical and visual analysis showed discrete size-gradated nanoparticle populations could be synthesized within a distribution tolerance of ±4 nm, which were optically unaffected in the presence of plasma/albumin. In normal mice, the cutoff for renal filtration of nanoparticles from blood into urine was ?11 nm. A linear relationship between body weight and PV was readily determined in mice administered far red fluorescent nanoparticles sized either 20 or 30 nm. PV measurements using nanoparticles were correlated to values obtained with Evans blue dye. Induced expansion or contraction of PV was demonstrated with albumin or furosemide administration, respectively, in mice. Longitudinal experiments >30 min required matched untreated control mice to correct for nanoparticle loss (?30%) putatively to the reticuloendothelial/phagocyte system. Collectively, the findings support a nanotechnology-based solution to methodological problems in measure of PV, notably in clinical settings where information on hemodynamic changes may improve treatment of injury and disease. PMID:22174395

  15. Coordination polymer based on cyano: Synthesis, crystal structure, and fluorescence

    SciTech Connect

    Fang Zhenlan; He Jiangang; Ju Qiang; Wu Xiaoyuan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Lu Canzhong, E-mail: czlu@fjirsm.ac.c [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2010-07-15

    One novel 2-D polythreading framework named as [Cu{sub 3}(CN){sub 3}(NH{sub 3})] (1), was obtained through the self-assembling of CuCN under hydrothermal reaction. It is remarkable that there is a 26-membered [Cu{sub 10}(CN){sub 8}] decanuclear metallamacrocycle with the effective size of ca. 16.8x6.83 A{sup 2} along the a-axis. These 2-D layers stack in an ..ABAB...staggered fashion, with the lateral {l_brace}(CN)Cu{sub 3}(NH{sub 3}){r_brace} moieties of each layer inserting into the voids of the decanuclear metallamacrocycles from two adjacent layers. Optical diffuse reflectance spectrum and the result of DFT calculation reveal that 1 is potential direct semiconducting material. In the solid state at room temperature, 1 shows bright yellow fluorescence under ultraviolet light illumination. Its emissive excited state is primarily attributed to the LMCT, LLCT and {sup 3}[MMLCT] excited state, based on the result of DFPT calculation. - Graphical abstract: One novel 2-D polythreading framework [Cu{sub 3}(CN){sub 3}(NH{sub 3})] (1) obtained through the self-assembling of CuCN under hydrothermal reaction shows bright yellow fluorescence at room temperature.

  16. Fluorescence-based detection methodologies for nitric oxide using transition metal scaffolds

    E-print Network

    Hilderbrand, Scott A. (Scott Alan), 1976-

    2004-01-01

    Chapter 1. Fluorescence-Based Detection Methodologies for Nitric Oxide: A Review. Chapter 2. Cobalt Chemistry with Mixed Aminotroponimine Salicylaldimine Ligands: Synthesis, Characterization, and Nitric Oxide Reactivity. ...

  17. High power light emitting diode based setup for photobleaching fluorescent impurities

    E-print Network

    Kaufman, Laura

    High power light emitting diode based setup for photobleaching fluorescent impurities Tobias K be photobleached before final sample preparation. The instrument consists of high power light emitting diodes

  18. Gold nanoparticle based surface enhanced fluorescence for detection of organophosphorus agents

    NASA Astrophysics Data System (ADS)

    Dasary, Samuel S. R.; Rai, Uma S.; Yu, Hongtao; Anjaneyulu, Yerramilli; Dubey, Madan; Ray, Paresh Chandra

    2008-07-01

    Organophosphorus agents (OPA) represent a serious concern to public safety as nerve agents and pesticides. Here we report the development of gold nanoparticle based surface enhanced fluorescence (NSEF) spectroscopy for rapid and sensitive screening of organophosphorus agents. Fluorescent from Eu 3+ ions that are bound within the electromagnetic field of gold nanoparticles exhibit a strong enhancement. In the presence of OPA, Eu 3+ ions are released from the gold nanoparticle surface and thus a very distinct fluorescence signal change was observed. We discussed the mechanism of fluorescence enhancement and the role of OPA for fluorescence intensity change in the presence of gold nanoparticles.

  19. Sensitive fluorescent detection of melamine in raw milk based on the inner filter effect of Au nanoparticles on the fluorescence of CdTe quantum dots.

    PubMed

    Zhang, Minwei; Cao, Xianyi; Li, Hongkun; Guan, Fengrui; Guo, Jiajia; Shen, Fei; Luo, Yeli; Sun, Chunyan; Zhang, Ligong

    2012-12-01

    A simple, rapid and sensitive fluorescent assay for determination of melamine has been developed based on inner filter effect (IFE) of gold nanoparticles (AuNPs) on the fluorescence of CdTe quantum dots (QDs). When thioglycolic acid-capped CdTe QDs was mixed with citrate-stabilized AuNPs, the fluorescence of CdTe QDs was significantly quenched via the IFE of AuNPs. With the presence of melamine, melamine could induce the aggregation and corresponding absorbance change of AuNPs, which then resulted in the recovery of IFE-decreased emission of CdTe QDs. Under the optimum conditions, the detection limit for melamine in raw milk was 0.02mgL(-1). The application of this method in samples of melamine-spiked raw milk suggested a recovery between 103% and 104%. Therefore, the obvious merits provided by the present assay, such as simplicity, rapidity, low cost, and high sensitivity, would make it promising for on-site screening of melamine adulterant in raw milk. PMID:22953938

  20. Fluorescent protein-based biosensors: resolving spatiotemporal dynamics of signaling

    PubMed Central

    DiPilato, Lisa M.; Zhang, Jin

    2009-01-01

    Summary Cellular processes are orchestrated by the precise coordination and regulation of molecular events in the cell. Fluorescent protein-based biosensors coupled with live-cell imaging have enabled the visualization of these events in real time and helped shape some of the current concepts of signal transduction, such as spatial compartmentation. The quantitative information produced by these tools has been incorporated into mathematical models that are capable of predicting highly complex and dynamic behaviors of cellular signaling networks, thus providing a systems level understanding of how pathways interact to produce a functional response. Finally, with technological advances in high throughput and in vivo imaging, these molecular tools promise to continually engender significant contributions to our understanding of cellular processes under normal and diseased conditions. PMID:19910237

  1. Coumarin-based fluorescent probes for H2S detection.

    PubMed

    Li, Wenhua; Sun, Wei; Yu, Xiaoqiang; Du, Lupei; Li, Minyong

    2013-01-01

    Although hydrogen sulfide (H(2)S) has been known as a toxic gas with unpleasant rotten egg smell, the correlation between H(2)S and physiological processes has attracted scientists to develop brand new methods to monitor such a gaseous molecule in vitro and in vivo. Herein, we described a couple of coumarin-based fluorescent probes (1a and 1b) that can be activated by reduction of azide to amine in the presence of H(2)S. It should be emphasized that probe 1b demonstrated high selectivity and sensitivity for H(2)S over other relevant reactive sulfur species in vitro, as well as identified exogenous H(2)S in living cells. PMID:23001475

  2. Bayesian-based deconvolution fluorescence microscopy using dynamically updated nonstationary expectation estimates.

    PubMed

    Wong, Alexander; Wang, Xiao Yu; Gorbet, Maud

    2015-01-01

    Fluorescence microscopy is widely used for the study of biological specimens. Deconvolution can significantly improve the resolution and contrast of images produced using fluorescence microscopy; in particular, Bayesian-based methods have become very popular in deconvolution fluorescence microscopy. An ongoing challenge with Bayesian-based methods is in dealing with the presence of noise in low SNR imaging conditions. In this study, we present a Bayesian-based method for performing deconvolution using dynamically updated nonstationary expectation estimates that can improve the fluorescence microscopy image quality in the presence of noise, without explicit use of spatial regularization. PMID:26054051

  3. Bayesian-based deconvolution fluorescence microscopy using dynamically updated nonstationary expectation estimates

    PubMed Central

    Wong, Alexander; Wang, Xiao Yu; Gorbet, Maud

    2015-01-01

    Fluorescence microscopy is widely used for the study of biological specimens. Deconvolution can significantly improve the resolution and contrast of images produced using fluorescence microscopy; in particular, Bayesian-based methods have become very popular in deconvolution fluorescence microscopy. An ongoing challenge with Bayesian-based methods is in dealing with the presence of noise in low SNR imaging conditions. In this study, we present a Bayesian-based method for performing deconvolution using dynamically updated nonstationary expectation estimates that can improve the fluorescence microscopy image quality in the presence of noise, without explicit use of spatial regularization. PMID:26054051

  4. Latest methods of fluorescence-based protein crystal identification

    PubMed Central

    Meyer, Arne; Betzel, Christian; Pusey, Marc

    2015-01-01

    Successful protein crystallization screening experiments are dependent upon the experimenter being able to identify positive outcomes. The introduction of fluorescence techniques has brought a powerful and versatile tool to the aid of the crystal grower. Trace fluorescent labeling, in which a fluorescent probe is covalently bound to a subpopulation (<0.5%) of the protein, enables the use of visible fluorescence. Alternatively, one can avoid covalent modification and use UV fluorescence, exploiting the intrinsic fluorescent amino acids present in most proteins. By the use of these techniques, crystals that had previously been obscured in the crystallization drop can readily be identified and distinguished from amorphous precipitate or salt crystals. Additionally, lead conditions that may not have been obvious as such under white-light illumination can be identified. In all cases review of the screening plate is considerably accelerated, as the eye can quickly note objects of increased intensity. PMID:25664782

  5. Fluorescence-based visualization of autophagic activity predicts mouse embryo viability

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Satoshi; Hara, Taichi; Yamamoto, Atsushi; Kito, Seiji; Minami, Naojiro; Kubota, Toshiro; Sato, Ken; Kokubo, Toshiaki

    2014-03-01

    Embryo quality is a critical parameter in assisted reproductive technologies. Although embryo quality can be evaluated morphologically, embryo morphology does not correlate perfectly with embryo viability. To improve this, it is important to understand which molecular mechanisms are involved in embryo quality control. Autophagy is an evolutionarily conserved catabolic process in which cytoplasmic materials sequestered by autophagosomes are degraded in lysosomes. We previously demonstrated that autophagy is highly activated after fertilization and is essential for further embryonic development. Here, we developed a simple fluorescence-based method for visualizing autophagic activity in live mouse embryos. Our method is based on imaging of the fluorescence intensity of GFP-LC3, a versatile marker for autophagy, which is microinjected into the embryos. Using this method, we show that embryonic autophagic activity declines with advancing maternal age, probably due to a decline in the activity of lysosomal hydrolases. We also demonstrate that embryonic autophagic activity is associated with the developmental viability of the embryo. Our results suggest that embryonic autophagic activity can be utilized as a novel indicator of embryo quality.

  6. Nanoparticle-based energy transfer for rapid and simple detection of protein glycosylation

    SciTech Connect

    Oh, Eunkeu; Lee, Dohoon; Kim, Young-Pil; Cha, Seung YOUP; Oh, Doo BEYONG; Kim, Jungbae; Kang, Hyun AH; Kim, Hak SUNG

    2006-12-04

    Glycan moiety of glycoproteins plays an essential role in its biological activity in vivo, and the analysis of glycosylation is of great importance in the development of protein therapeutics. In this study, we report a rapid and simple detection of protein glycosylation based on the fluorescence resonance energy transfer (FRET) between concanavalin A-conjugated gold nanoparticles (ConA-AuNPs) and dextran-conjugated quantum dots (Dex-QDs). The increased photoluminescence (PL) signals of Dex-QDs due to the competitive inhibition of glycoproteins were well correlated with the glycosylation chain length of glucose oxidases as well as the mannosylation degree of bovine serum albumin (BSA). The parallel analysis of the diversely mannosylated BSAs using an image analyzer further demonstrated the potential of this new technique in high-throughput screening of glycoprotein and carbohydrate therapeutics.

  7. Fluorescence Rise Time Measurements for High Temperature Fluorescence-Based Thermometry

    SciTech Connect

    Allison, S.W.

    2005-03-24

    Certain ceramic-like phosphor materials exhibit bright fluorescence with a pronounced temperature dependence over a range which spans the cryogenic to 1700 C, depending on the specific phosphor. To measure temperature, a surface, for instance a turbine blade, is coated with the material. An optical system, sometimes including optical fibers, conveys stimulating light and collects the emission for analysis. Either emission intensity or decay time may indicate temperature. Previously fielded tests have involved surfaces such as blades, vanes, pistons, in-take valves, sheets of galvanneal steel, etc. The fluorescent coatings may be applied to small parts via sputtering methods or to large areas by mixture with inorganic binders. Presented here are results characterizing fluorescence rise times as a means of determining temperature from ambient to 700 C for Y{sub 2}O{sub 3}:Eu.

  8. Transcript quantification based on chemical labeling of RNA associated with fluorescent detection.

    PubMed

    Fontaine, L; Even, S; Soucaille, P; Lindley, N D; Cocaign-Bousquet, M

    2001-11-15

    A general method for RNA measurement, based on chemical labeling of RNA with digoxigenin (without retrotranscription), has been established. Labeled RNA is hybridized with nylon membranes containing spot blots of PCR-amplified gene fragments and the fluorescence detection is mediated via specific anti-digoxigenin antibody coupled to alkaline phosphatase. The method was optimized in order to be quantitative, and high precision (less than 24% error) was obtained, allowing analysis of relatively small changes in gene expression. When the quantity of cellular RNA used in this method is maintained constant and the amount of RNA in the cell determined, the true intracellular transcript concentrations can be determined, rather than simple abundance of a messenger in RNA population. This RNA quantification technique was extended to macroarrays blotted automatically and the validity of the method was tested by comparison with expression data obtained by Northern blotting. PMID:11700979

  9. Continuous fluorescence anisotropy-based assay of BOCILLIN FL penicillin reaction with penicillin binding protein 3.

    PubMed

    Shapiro, Adam B; Gu, Rong-Fang; Gao, Ning; Livchak, Stephania; Thresher, Jason

    2013-08-01

    We report a simple, rapid, and reproducible fluorescence anisotropy-based method for measuring rate constants for acylation and deacylation of soluble penicillin binding protein (PBP) constructs by compounds in microtiter plates by means of competition with time-dependent acylation by BOCILLIN FL. The method is demonstrated by measuring the acylation rate constants of the PBP3 periplasmic domains from Pseudomonas aeruginosa and Acinetobacter baumannii by BOCILLIN FL, aztreonam, meropenem, and ceftazidime. The new method requires very little protein and can be completed in approximately 1h per compound. A set of BOCILLIN FL acylation progress curves collected over a range of competitor concentrations is fit globally to a kinetic model by numerical integration. First-order deacylation rate constants could also be measured, as demonstrated with a catalytically impaired mutant OXA-10 ?-lactamase. PMID:23603065

  10. Validation of a simple and fast method to quantify in vitro mineralization with fluorescent probes used in molecular imaging of bone

    SciTech Connect

    Moester, Martiene J.C. [Department of Radiology, Leiden University Medical Center (Netherlands)] [Department of Radiology, Leiden University Medical Center (Netherlands); Schoeman, Monique A.E. [Department of Orthopedic Surgery, Leiden University Medical Center (Netherlands)] [Department of Orthopedic Surgery, Leiden University Medical Center (Netherlands); Oudshoorn, Ineke B. [Department of Radiology, Leiden University Medical Center (Netherlands) [Department of Radiology, Leiden University Medical Center (Netherlands); Percuros BV, Leiden (Netherlands)] [Netherlands; Beusekom, Mara M. van [Department of Radiology, Leiden University Medical Center (Netherlands)] [Department of Radiology, Leiden University Medical Center (Netherlands); Mol, Isabel M. [Department of Radiology, Leiden University Medical Center (Netherlands) [Department of Radiology, Leiden University Medical Center (Netherlands); Percuros BV, Leiden (Netherlands)] [Netherlands; Kaijzel, Eric L.; Löwik, Clemens W.G.M. [Department of Radiology, Leiden University Medical Center (Netherlands); Rooij, Karien E. de, E-mail: k.e.de_rooij@lumc.nl [Department of Radiology, Leiden University Medical Center (Netherlands) [Department of Radiology, Leiden University Medical Center (Netherlands); Percuros BV, Leiden (Netherlands)] [Netherlands

    2014-01-03

    Highlights: •We validate a simple and fast method of quantification of in vitro mineralization. •Fluorescently labeled agents can detect calcium deposits in the mineralized matrix of cell cultures. •Fluorescent signals of the probes correlated with Alizarin Red S staining. -- Abstract: Alizarin Red S staining is the standard method to indicate and quantify matrix mineralization during differentiation of osteoblast cultures. KS483 cells are multipotent mouse mesenchymal progenitor cells that can differentiate into chondrocytes, adipocytes and osteoblasts and are a well-characterized model for the study of bone formation. Matrix mineralization is the last step of differentiation of bone cells and is therefore a very important outcome measure in bone research. Fluorescently labelled calcium chelating agents, e.g. BoneTag and OsteoSense, are currently used for in vivo imaging of bone. The aim of the present study was to validate these probes for fast and simple detection and quantification of in vitro matrix mineralization by KS483 cells and thus enabling high-throughput screening experiments. KS483 cells were cultured under osteogenic conditions in the presence of compounds that either stimulate or inhibit osteoblast differentiation and thereby matrix mineralization. After 21 days of differentiation, fluorescence of stained cultures was quantified with a near-infrared imager and compared to Alizarin Red S quantification. Fluorescence of both probes closely correlated to Alizarin Red S staining in both inhibiting and stimulating conditions. In addition, both compounds displayed specificity for mineralized nodules. We therefore conclude that this method of quantification of bone mineralization using fluorescent compounds is a good alternative for the Alizarin Red S staining.

  11. Skin fluorescence model based on the Monte Carlo technique

    Microsoft Academic Search

    Dmitry Y. Churmakov; Igor V. Meglinski; Sergey A. Piletsky; Douglas A. Greenhalgh

    2003-01-01

    The novel Monte Carlo technique of simulation of spatial fluorescence distribution within the human skin is presented. The computational model of skin takes into account spatial distribution of fluorophores following the collagen fibers packing, whereas in epidermis and stratum corneum the distribution of fluorophores assumed to be homogeneous. The results of simulation suggest that distribution of auto-fluorescence is significantly suppressed

  12. Complexation induced fluorescence and acid-base properties of dapoxyl dye with ?-cyclodextrin: a drug-binding application using displacement assays.

    PubMed

    Pal, Kaushik; Mallick, Suman; Koner, Apurba L

    2015-06-28

    Host-guest complexation of dapoxyl sodium sulphonate (DSS), an intramolecular charge transfer dye with water-soluble and non-toxic macrocycle ?-cyclodextrin (?-CD), has been investigated in a wide pH range. Steady-state absorption, fluorescence and time-resolved fluorescence measurements confirm the positioning of DSS into the hydrophobic cavity of ?-CD. A large fluorescence enhancement ca. 30 times, due to 1?:?2 complex formation and host-assisted guest-protonation have been utilised for developing a method for the utilisation of CD based drug-delivery applications. A simple fluorescence-displacement based approach is implemented at physiological pH for the assessment of binding strength of pharmaceutically useful small drug molecules (ibuprofen, paracetamol, methyl salicylate, salicylic acid, aspirin, and piroxicam) and six important antibiotic drugs (resazurin, thiamphenicol, chloramphenicol, ampicillin, kanamycin, and sorbic acid) with ?-CD. PMID:26028009

  13. Turn-on fluorescent dopamine sensing based on in situ formation of visible light emitting polydopamine nanoparticles.

    PubMed

    Yildirim, Adem; Bayindir, Mehmet

    2014-06-01

    Dopamine is the principle biomarker for diseases such as schizophrenia, Huntington's, and Parkinson's, and the need is urgent for rapid and sensitive detection methods for diagnosis and monitoring of such diseases. In this Article, we report a turn-on fluorescent method for rapid dopamine sensing which is based on monitoring the intrinsic fluorescence of in situ synthesized polydopamine nanoparticles. The assay uses only a common base and an acid, NaOH and HCl to initiate and stop the polymerization reaction, respectively, which makes the assay extremely simple and low cost. First, we studied the in situ optical properties of polydopamine nanoparticles, for the first time, which formed under different alkaline conditions in order to determine optimum experimental parameters. Then, under optimized conditions we demonstrated high sensitivity (40 nM) and excellent selectivity of the assay. With its good analytical figures of merit, the described method is very promising for detection of dopamine related diseases. PMID:24803112

  14. Synthesis and properties of novel base-discriminating fluorescent (BDF) nucleosides.

    PubMed

    Saito, Yoshio; Hanawa, Kazuo; Hayashi, Keigo; Motegi, Kaori; Okaoto, Akimitsu; Saito, Isao

    2005-01-01

    We designed a new type of pyrene-labeled base-discrimination fluorescent (BDF) nucleosides (Py)U, (Py)C, (8Py)A and (MePy)dA, which emitted strong fluorescence only when the bases opposite the BDF base are A, G, T and C, respectively. The DNA probes containing four different BDF bases enable us to distinguish single base alterations by simply mixing with a sample solution of target DNA. PMID:17150679

  15. Fluorescence resonance energy transfer-based near-infrared fluorescence sensor for glucose monitoring.

    PubMed

    Ballerstadt, Ralph; Gowda, Ashok; McNichols, Roger

    2004-04-01

    A novel near-infrared (NIR) fluorescence affinity sensor for continuous glucose monitoring was developed and characterized. The sensor operates by fluorescence resonance energy transfer between a NIR chromophore linked to concanavalin A (ConA) and an NIR fluorophore linked to free dextran. The binding of dextran with ConA in the absence of glucose results in low fluorescence due to quenching; however, the quenching is reversed by competitive displacement of dextran from ConA by glucose. In order to increase thermodynamic stability and the lifetime of the sensor, ConA was immobilized within a macroporous bead matrix. The sensor was contained within a sealed hollow dialysis fiber (o.d. 215 microm, wall thickness 20 microm), preventing the macromolecules from leaking out and enabling glucose to rapidly enter the fiber lumen. A glucose-insensitive reference fluorophore was also incorporated to allow for ratiometric measurements, resulting in a robust sensor output that is independent of positional and/or light intensity changes. The response of the fluorescence affinity sensor to glucose was tested continuously in an automated test chamber at 37 degrees C. The sensor showed good dynamic range within physiologically relevant glucose concentration range (15% change over 2.5-30 mM, no hysteresis), fast response time (2-4 min), and a remarkable long-term stability (6 months). We interpret the improved longevity of this sensor to be the result of an optimized photo exposure regime and immobilization of ConA to the matrix. Its small size, ratiometric output, and NIR fluorescence make this sensor well suited for dermal implantation and continuous transdermal monitoring. PMID:15117585

  16. Synthesis of fluorescent carbon dots via simple acid hydrolysis of bovine serum albumin and its potential as sensitive sensing probe for lead (II) ions.

    PubMed

    Wee, Shui Shui; Ng, Yann Huey; Ng, Sing Muk

    2013-11-15

    Carbon dots have great potential to be utilised as an optical sensing probe due to its unique photoluminescence and less toxic properties. This work reports a simple and novel synthesis method of carbon dots via direct acid hydrolysis of bovine serum albumin protein in a one-pot approach. Optimisation of the important synthetic parameters has been performed which consists of temperature effect, acid to protein ratio and kinetics of reaction. Higher temperature has promoted better yield with shorter reaction time. The carbon dots obtained shows a strong emission at the wavelength of 400 nm with an optimum excitation of 305 nm. The potential of the carbon dots as optical sensing probe has been investigated on with different cations that are of environmental and health concern. The fluorescence of the carbon dots was significantly quenched particularly by lead (II) ions in a selective manner. Further analytical study has been performed to leverage the performance of the carbon dots for lead (II) ions sensing using the standard Stern-Volmer relationship. The sensing probe has a dynamic linear range up to 6.0 mM with a Stern-Volmer constant of 605.99 M(-1) and a limit of detection (LOD) of 5.05 ?M. The probe performance was highly repeatable with a standard deviation below 3.0%. The probe suggested in this study demonstrates the potential of a more economical and greener approach that uses protein based carbon dots for sensing of heavy metal ions. PMID:24148375

  17. A fluorescent biosensor based on carbon dots-labeled oligodeoxyribonucleotide and graphene oxide for mercury (II) detection.

    PubMed

    Cui, Xin; Zhu, Lei; Wu, Jing; Hou, Yu; Wang, Peiyao; Wang, Zhenni; Yang, Mei

    2015-01-15

    As the newest two members of the carbon materials family, carbon dots (CDs) and graphene oxide (GO) possess many excellent optical properties resulting in a wide range of applications. In this work, we successfully synthesized CDs with a high-quantum-yield, and labeled them on oligodeoxyribonucleotide (ODN). The fluorescence of resultant CDs-labeled oligodeoxyribonucleotide (ODN-CDs) was quenched by GO via fluorescence resonance energy transfer. In the presence of Hg(2+), the fluorescence was recovered by the release of ODN-CDs from GO due to the formation of T-Hg(2+)-T duplex. In the light of this theory, we designed a simple, highly sensitive and selective fluorometric Hg(2+) sensor based on CDs-labeled oligodeoxyribonucleotide and GO without complicated, costly and time-consuming operations. Under the optimal conditions, a linear relationship was obtained between relative fluorescence intensity and the concentration of Hg(2+) in the range of 5-200 nM (R(2)=0.974). The present GO-based sensor system is highly selective toward Hg(2+) over a wide range of metal ions and has a detection limit of 2.6 nM. This method is reliable, and has been successfully applied for the detection of Hg(2+) in practical samples. PMID:25137567

  18. Sensitive detection of ochratoxin A in wine and cereals using fluorescence-based immunosensing.

    PubMed

    Prieto-Simón, Beatriz; Karube, Isao; Saiki, Hiroshi

    2012-12-01

    Ochratoxin A (OTA) is a mycotoxin found in a wide range of food and feedstuffs. Intake of OTA-contaminated food causes health concern due to the harmful effects reported on humans and animals. Much effort is currently devoted to set up and optimise highly sensitive and accurate methods of OTA analysis. This work describes the comparison of fluorescence-based immunosensing strategies for the analysis of OTA. First, an indirect competitive fluoroimmunoassay was designed and optimised. The assay enabled the quantification of the toxin at the levels set by the European legislation. Then, a flow-immunoassay based on kinetic exclusion measurements was developed. It showed the theoretical lowest limit of detection enabled by the affinity of the anti-OTA antibody (IC(80)=12ngL(-1) in the assay solution). Wine and cereal samples were analysed using the optimised flow system. No significant matrix effects were observed after simple pre-treatment of wine and OTA extraction from corn-flakes samples. This simple and highly sensitive automated biosensing-system allows OTA quantification in food and beverages. It is envisaged as a powerful tool for rapid and reliable toxin screening. PMID:22953861

  19. A Cell-Based Functional Assay Using a Green Fluorescent Protein-Based Calcium Indicator dCys-GCaMP

    PubMed Central

    Cai, Bin; Chen, Xia; Liu, Fang; Li, Jun; Gu, Lijuan; Liu, Jason R.

    2014-01-01

    Abstract Measurement of the changes in intracellular Ca2+ levels is an important assay for drug discovery. In this report, we describe a novel Ca2+ indicator, dCys-GCaMP, based on the green fluorescent protein and the development of a rapid and simple cell-based functional assay using this new Ca2+ indicator. We demonstrated the sensitivity and reliability of the assay by measuring the cellular responses to the agonists, antagonists, channel blockers, and modulators of the ionotropic N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. HEK293 cells coexpressing the NMDA receptor and dCys-GCaMP displayed a strong increase in fluorescence intensity when stimulated with the agonist glutamate. This increase in the fluorescence signal was agonist concentration dependent and could be blocked by NMDAR antagonists and channel blockers. The pharmacological parameters measured with the dCys-GCaMP assay are in close agreement with those derived from conventional assays with synthetic dye fluo-4 and literature values. In addition, we showed that this assay could be used on G protein-coupled receptors as well, as exemplified by studies on the ?1A adrenergic receptor. A limited scale evaluation of the assay performance in a 96-well compound screening format suggests that the dCys-GCaMP assay could be easily adapted to a high-throughput screening environment. The most important advantage of this new assay over the conventional fluo-4 and aequorin assays is the elimination of the dye-loading or substrate-loading process. PMID:25105973

  20. Neoplasm diagnostics based on fluorescence of polymethine dyes

    NASA Astrophysics Data System (ADS)

    Samtsov, Michael P.; Voropay, Eugene S.; Chalov, Vadim N.; Zhavrid, Edvard A.

    2002-05-01

    Investigated polymethine dye TICS has near IR bands of fluorescence and absorption within the transparency region of biological tissues. It can be detected up to 1.5 cm from the surface of the skin. The intensity of a fluorescence signal of TICS is linear for doses up to 2 mg/kg in both tumor and muscle tissue. The ratio of an intensity of light induced fluorescence in tumor tissue to one in muscle tissue is up to 3.6 for rapidly growing tumors. The retention time of TICS is 7 days in all tissues. TICS can be used in the detection of tumor boundaries and tumor internal structure.

  1. A facile fluorescence method for versatile biomolecular detection based on pristine ?-Fe?O? nanoparticle-induced fluorescence quenching.

    PubMed

    Song, Chan; Wang, Guan-Yao; Kong, De-Ming

    2015-06-15

    This work investigated the interactions of ?-Fe2O3 nanoparticles (NPs) with different structural nucleic acids and their fluorescence quenching ability towards fluorophore-labelled nucleic acid probes. Different from bulk ?-Fe2O3 samples, nanoscale ?-Fe2O3 particles exhibit the unique properties of strong adsorption and fluorescence quenching to fluorophore-labelled single-stranded DNA (ssDNA) probes. Based on these findings, a facile fluorescence method was developed for versatile quantification of nucleic acids. The size scale of NPs makes a significant impact on this sensing platform. Better selectivity was given by bigger NP (50-100 nm)-based nucleic acid-sensing platform compared with smaller NP (30 nm)-based one. In the 50-100 nm ?-Fe2O3 NP-based sensing platform, single nucleotide mismatch or single base-pair mismatch can even be effectively discriminated. The targets of micro-RNA (miRNA), ssDNA and double-stranded DNA (dsDNA) are sensitively detected with detection limits of 0.8 nM, 1.1 nM and 0.64 nM (S/N=3), respectively. Significantly, ?-Fe2O3 NPs possess different affinities towards ssDNA probes with different lengths, and can be used as a universal quencher for ssDNA probes labelled with different fluorescent dyes. On the basis of these properties, the pristine ?-Fe2O3 NPs hold the potential to be widely utilized in the development of novel biosensors with signal amplification or simultaneous multiple target detection strategies. PMID:25588703

  2. Cytometric sorting based on the fluorescence lifetime of spectrally overlapping signals

    PubMed Central

    Cao, Ruofan; Pankayatselvan, Varayini; Houston, Jessica P.

    2013-01-01

    Flow cytometry is a well-established and powerful high-throughput fluorescence measurement tool that also allows for the sorting and enrichment of subpopulations of cells expressing unique fluorescence signatures. Owing to the reliance on intensity-only signals, flow cytometry sorters cannot easily discriminate between fluorophores that spectrally overlap. In this paper we demonstrate a new method of cell sorting using a fluorescence lifetime-dependent methodology. This approach, referred to herein as phase-filtered cell sorting (PFCS), permits sorting based on the average fluorescence lifetime of a fluorophore by separating fluorescence signals from species that emit differing average fluorescence lifetimes. Using lifetime-dependent hardware, cells and microspheres labeled with fluorophores were sorted with purities up to 90%. PFCS is a practical approach for separating populations of cells that are stained with spectrally overlapping fluorophores or that have interfering autofluorescence signals. PMID:23787669

  3. A turn-on fluorescent probe for hypochlorous acid based on the oxidation of diphenyl telluride.

    PubMed

    Venkatesan, Parthiban; Wu, Shu-Pao

    2015-02-21

    A fluorescent probe HCTe was developed for rapid detection of hypochlorous acid based on the specific HOCl-promoted oxidation of diphenyl telluride. The reaction is accompanied by an 82-fold increase in the fluorescence quantum yield (from 0.009 to 0.75). The fluorescence turn-on mechanism is achieved by the suppression of photoinduced electron transfer (PET) from the diphenyl telluride group to BODIPY. The fluorescence intensity of the reaction between HOCl and HCTe is linear in the HOCl concentration range of 1 to 10 ?M with a detection limit of 41.3 nM (S/N = 3). In addition, confocal fluorescence microscopy imaging using RAW264.7 macrophages demonstrated that HCTe could be an efficient fluorescent probe for HOCl detection in living cells. PMID:25580477

  4. A fluorescence-based cyclodextrin sensor to detect nitroaromatic explosives

    Microsoft Academic Search

    Aravindan Ponnu; Eric V. Anslyn

    2010-01-01

    We report the use of a cyclodextrin inclusion complex (CIC) in fluorescence sensing to provide a method to classify energetic nitroaromatic compounds. A CIC was prepared by the inclusion of 9,10-bis(phenylethynyl)anthracene (BPEA) with ?-cyclodextrin (CD) (BPEA\\/CD) in water with 5% tetrahydrofuran by volume. The inclusion behaviour of BPEA with ?-CD was studied by fluorescence spectroscopy. The effect of ?- and

  5. Glucose sensing based on the intrinsic fluorescence of sol-gel immobilized yeast hexokinase

    E-print Network

    Strathclyde, University of

    Glucose sensing based on the intrinsic fluorescence of sol-gel immobilized yeast hexokinase Faeiza of the intrinsic fluorescence of yeast hexokinase as an assay for glucose and immo- bilization of the enzyme in a silica sol-gel matrix as a potential in vivo glucose sensor for use in patients with diabetes

  6. Protein-based fluorescent metal nanoclusters for small molecular drug screening.

    PubMed

    Yu, Yong; New, Siu Yee; Xie, Jianping; Su, Xiaodi; Tan, Yen Nee

    2014-11-18

    A facile drug screening method based on synthesis of fluorescent gold nanoclusters inside albumin proteins loaded with small molecular drugs and comparing the relative fluorescence intensities of the resultant gold nanoclusters has been developed and successfully applied for the quantitative measurement of drug-protein binding constants. PMID:25253537

  7. Potential fluorescent chemosensor based on L-tryptophan derivative: DFT based ESIPT process

    NASA Astrophysics Data System (ADS)

    Jayabharathi, Jayaraman; Thanikachalam, Venugopal; Vennila, Munusamy; Jayamoorthy, Karunamoorthy

    The spectroscopic properties of (E)-2-(2-hydroxybenzylideneamino)-3-(1H-indol-3-yl) propanoic acid (HBDIPPA) has been studied in a series of different solvents. An excited state intramolecular proton transfer (ESIPT) process in hydroxy Schiff base has been studied using emission spectroscopy. DFT calculations on energy, HOMO-LUMO energies, MEP, dipole moment, charge distribution of the Schiff base derivative have been performed and discussed. The energy barrier for the interconversion of two rotamers is too high in the excited state than the ground state is shown by PES calculation. Positive values of laplacian ?2?(rc) (2.81) and electron density ?(rc) (0.22) are indicative of hydrogen bonds interactions. Absorption as well as fluorescence wavenumbers are correlated with Marcus and Reichardt-Dimroth solvent functions and also with Taft and Catalan solvent parameters. Schiff base HBDIPPA can be used as a new fluorescent sensor.

  8. Potential fluorescent chemosensor based on L-tryptophan derivative: DFT based ESIPT process.

    PubMed

    Jayabharathi, Jayaraman; Thanikachalam, Venugopal; Vennila, Munusamy; Jayamoorthy, Karunamoorthy

    2012-09-01

    The spectroscopic properties of (E)-2-(2-hydroxybenzylideneamino)-3-(1H-indol-3-yl) propanoic acid (HBDIPPA) has been studied in a series of different solvents. An excited state intramolecular proton transfer (ESIPT) process in hydroxy Schiff base has been studied using emission spectroscopy. DFT calculations on energy, HOMO-LUMO energies, MEP, dipole moment, charge distribution of the Schiff base derivative have been performed and discussed. The energy barrier for the interconversion of two rotamers is too high in the excited state than the ground state is shown by PES calculation. Positive values of laplacian ?(2)?((rc)) (2.81) and electron density ?((rc)) (0.22) are indicative of hydrogen bonds interactions. Absorption as well as fluorescence wavenumbers are correlated with Marcus and Reichardt-Dimroth solvent functions and also with Taft and Catalan solvent parameters. Schiff base HBDIPPA can be used as a new fluorescent sensor. PMID:22580140

  9. Simple Spatial Analysis based on Raster Data Structure

    NSDL National Science Digital Library

    Wei Luo

    Wei Luo, Northern Illinois University Summary This is a simple lab exercise early in the semester to teach student the limitation of raster data structure, simple buffer and overlay operation without using ...

  10. Detection of glucose via enzyme-coupling reaction based on a DT-diaphorase fluorescence probe.

    PubMed

    Gao, Xinghui; Li, Xiaohua; Wan, Qiongqiong; Li, Zhao; Ma, Huimin

    2014-03-01

    Enzyme-coupling reactions play an important role in the assay of analytes. In this manuscript, we developed a new fluorescent probe for the detection of glucose through the enzyme-coupling reaction of DT-diaphorase (DTD). The probe was synthesized through a mild and simple synthetic procedure, and showed good fluorescence response to DTD. The reactions for the detection of glucose proceed as follows: glucose dehydrogenase oxidizes glucose to gluconolactone with NAD(+) as the electron acceptor to yield NADH, and NADH can be utilized by DTD to further react with the probe releasing resorufin. As a result of these tandem reactions, fluorescence off-on response will occur. The method showed high selectivity for glucose with a detection limit of 0.2 µM, which may provide a potential way for fluorescence detection of glucose through enzyme-coupling reactions. Furthermore, the applicability of the method has been demonstrated by detecting glucose in human urine samples. PMID:24468396

  11. A simple parallel tandem organic solar cell based on metallophthalocyanines

    NASA Astrophysics Data System (ADS)

    Yuen, Avery P.; Hor, Ah-Mee; Preston, John S.; Klenkler, Richard; Bamsey, Nathan M.; Loutfy, Rafik O.

    2011-04-01

    A simple parallel tandem solar cell based on a combination of Zn-phthalocyanine (Pc) and ClInPc has been fabricated and characterized. Compared to a traditional series tandem cell, parallel tandem cells eliminate the need for a semitransparent recombination layer, reducing the complexity of device fabrication while still providing an excellent increase in device performance. Results show a realized broadening of the spectral response and enhancement of the external quantum efficiency as a result of the complementary absorption profiles of ZnPc and ClInPc in the near infrared region. Introduction of a blended ClInPc:C60 layer is shown to more than double the power conversion efficiency of a standard ZnPc/C60 bilayer device (PCE=0.86%). The enhanced performance of the parallel tandem (PCE=1.81%) arises from an increase in both the open circuit voltage and the short circuit current.

  12. A novel method for non-transferrin-bound iron quantification by chelatable fluorescent beads based on flow cytometry.

    PubMed

    Ma, Yongmin; Podinovskaia, Maria; Evans, Patricia J; Emma, Giovanni; Schaible, Ulrich E; Porter, John; Hider, Robert C

    2014-11-01

    The reliable measurement of non-transferrin-bound iron (NTBI) in serum has proved to be difficult and generally time consuming. We have sought a simple and fast method for such a determination. We adopted a fluorescence assay and designed a fluorescent dye with a chelating agent attached to sense iron. To avoid autofluorescence from serum samples, the iron probes were linked to beads and the autofluorescence could be separated and excluded from the measurement by flow cytometry due to the size difference between beads and serum proteins. Fluorescent beads containing both fluorescent and chelating moieties have been synthesized. The nature of the chelating function has been systematically investigated using four different chelators: bidentate hydroxypyranone, bidentate hydroxypyridinone, hexadentate hydroxypyranone and hexadentate hydroxypyridinone, each with different iron affinity constants. Competition studies demonstrate that the hexadentate hydroxypyridinone-based beads are capable of scavenging most of low molecular mass and albumin-bound iron but negligible amounts of iron from transferrin and ferritin. Serum samples from 30 patients with different types of disease and normal volunteers were measured. The concentrations of NTBI fall in the range -0.41 to +6.5 ?M. The data have been compared with those obtained from the traditional 'NTA' method. PMID:25093426

  13. An improved respiratory syncytial virus neutralization assay based on the detection of green fluorescent protein expression and automated plaque counting

    PubMed Central

    2012-01-01

    Background Virus neutralizing antibodies against respiratory syncytial virus (RSV) are considered important correlates of protection for vaccine evaluation. The established plaque reduction assay is time consuming, labor intensive and highly variable. Methods Here, a neutralization assay based on a modified RSV strain expressing the green fluorescent protein in combination with automated detection and quantification of plaques is described. Results The fluorescence plaque reduction assay in microplate format requires only two days to complete and is simple and reproducible. A good correlation between visual and automated counting methods to determine RSV neutralizing serum antibody titers was observed. Conclusions The developed virus neutralization assay is suitable for high-throughput testing and can be used for both animal studies and (large scale) vaccine clinical trials. PMID:23114196

  14. Rapid and sensitive detection of ?-agonists using a portable fluorescence biosensor based on fluorescent nanosilica and a lateral flow test strip.

    PubMed

    Song, Chunmei; Zhi, Aimin; Liu, Qingtang; Yang, Jifei; Jia, Guochao; Shervin, Jahanian; Tang, Liang; Hu, Xiaofei; Deng, Ruiguang; Xu, Chuanlai; Zhang, Gaiping

    2013-12-15

    A portable fluorescence biosensor with rapid and ultrasensitive response for Clenbuterol (CL) has been built up with fluorescent nanosilica and a lateral flow test strip. Quantitative detection of CL was realized by recording the fluorescence intensity of fluorescent nanosilica captured on the test line. The sensing results indicated that the sensitivity of the fluorescent nanosilica-based strip was better than that of conventional colloidal gold-based strips. The visual limit of detection of the strip for qualitative detection was 0.1 ng/mL while the LOD for quantitative detection could down to 0.037 ng/mL by using fluorescence biosensor. The recoveries of test samples were from 89.3% to 97.7%. The assay time for CL detection was less than 8 min, suitable for rapid testing on-site. PMID:23835218

  15. A starting point for fluorescence-based single-molecule measurements in biomolecular research.

    PubMed

    Gust, Alexander; Zander, Adrian; Gietl, Andreas; Holzmeister, Phil; Schulz, Sarah; Lalkens, Birka; Tinnefeld, Philip; Grohmann, Dina

    2014-01-01

    Single-molecule fluorescence techniques are ideally suited to provide information about the structure-function-dynamics relationship of a biomolecule as static and dynamic heterogeneity can be easily detected. However, what type of single-molecule fluorescence technique is suited for which kind of biological question and what are the obstacles on the way to a successful single-molecule microscopy experiment? In this review, we provide practical insights into fluorescence-based single-molecule experiments aiming for scientists who wish to take their experiments to the single-molecule level. We especially focus on fluorescence resonance energy transfer (FRET) experiments as these are a widely employed tool for the investigation of biomolecular mechanisms. We will guide the reader through the most critical steps that determine the success and quality of diffusion-based confocal and immobilization-based total internal reflection fluorescence microscopy. We discuss the specific chemical and photophysical requirements that make fluorescent dyes suitable for single-molecule fluorescence experiments. Most importantly, we review recently emerged photoprotection systems as well as passivation and immobilization strategies that enable the observation of fluorescently labeled molecules under biocompatible conditions. Moreover, we discuss how the optical single-molecule toolkit has been extended in recent years to capture the physiological complexity of a cell making it even more relevant for biological research. PMID:25271426

  16. A simple microviscometric approach based on Brownian motion tracking.

    PubMed

    Hnyluchová, Zuzana; Bjalon?íková, Petra; Karas, Pavel; Mravec, Filip; Halasová, Tereza; Peka?, Miloslav; Kubala, Lukáš; Víte?ek, Jan

    2015-02-01

    Viscosity-an integral property of a liquid-is traditionally determined by mechanical instruments. The most pronounced disadvantage of such an approach is the requirement of a large sample volume, which poses a serious obstacle, particularly in biology and biophysics when working with limited samples. Scaling down the required volume by means of microviscometry based on tracking the Brownian motion of particles can provide a reasonable alternative. In this paper, we report a simple microviscometric approach which can be conducted with common laboratory equipment. The core of this approach consists in a freely available standalone script to process particle trajectory data based on a Newtonian model. In our study, this setup allowed the sample to be scaled down to 10 ?l. The utility of the approach was demonstrated using model solutions of glycerine, hyaluronate, and mouse blood plasma. Therefore, this microviscometric approach based on a newly developed freely available script can be suggested for determination of the viscosity of small biological samples (e.g., body fluids). PMID:25725855

  17. Knowledge-based vision and simple visual machines.

    PubMed Central

    Cliff, D; Noble, J

    1997-01-01

    The vast majority of work in machine vision emphasizes the representation of perceived objects and events: it is these internal representations that incorporate the 'knowledge' in knowledge-based vision or form the 'models' in model-based vision. In this paper, we discuss simple machine vision systems developed by artificial evolution rather than traditional engineering design techniques, and note that the task of identifying internal representations within such systems is made difficult by the lack of an operational definition of representation at the causal mechanistic level. Consequently, we question the nature and indeed the existence of representations posited to be used within natural vision systems (i.e. animals). We conclude that representations argued for on a priori grounds by external observers of a particular vision system may well be illusory, and are at best place-holders for yet-to-be-identified causal mechanistic interactions. That is, applying the knowledge-based vision approach in the understanding of evolved systems (machines or animals) may well lead to theories and models that are internally consistent, computationally plausible, and entirely wrong. PMID:9304684

  18. Comparison of fluorescence-based semi-automated genotyping of multiple microsatellite loci with autoradiographic techniques

    Microsoft Academic Search

    D. A. Schwengel; A. E. Jedlicka; R. C. Levitt

    1994-01-01

    The practical application of highly efficient fluorescence-based methods for the semi-automated genotyping of polymerase chain reaction-based microsatellite markers will depend on the development of robust protocols that provide accurate and reproducible data. In the present report the authors compare the accuracy of a fluorescence-based protocol with a benchmark radiolabeling method that depends on a known sequence ladder or amplified DNA

  19. A simple but highly selective and sensitive fluorescence reporter for toxic CdII ion via excimer formation

    NASA Astrophysics Data System (ADS)

    Samanta, Anuva; Guchhait, Nikhil; Bhattacharya, Subhash Chandra

    2014-09-01

    High selectivity and fluorescence sensitivity of a well-recognized antiexcitotoxic and anticonvulsant drug, kynurenic acid (KA), toward CdII ion has been demonstrated by UV-vis, fluorescence, 1H NMR spectroscopy in combination with computational calculations. Upon complexation with CdII, KA exhibits a distinct excimer emission at 528 nm along with monomer emission at 402 nm. The sensing ability of drug KA toward CdII ion is distinctly different from sensing for HgII or CuII ion. KA can form dimer by intermolecular O-H⋯O hydrogen bonding between the -COOH groups. Presence of CdII metal ions promotes dimer formation in the excited state which exhibits excimer fluorescence.

  20. A simple "add and measure" FRET-based telomeric tandem repeat sequence detection and telomerase assay method.

    PubMed

    Kawamura, Koji; Yaku, Hidenobu; Miyoshi, Daisuke; Murashima, Takashi

    2014-02-14

    A simple and sensitive method for measuring telomeric tandem repeat DNA and telomerase activity based on fluorescence resonance energy transfer (FRET) with a FAM-modified 12-mer ODN probe as a donor (fluorophore) and ethidium bromide (EB) as an acceptor (quencher) is proposed. When telomeric DNA and the FAM-modified probe form a duplex, EB intercalates between base-pairs, resulting in fluorescence quenching of FAM through FRET from FAM to EB. This method can be used to estimate the amount of telomeric DNAs in a sample solution as the molar concentration of the telomeric DNA unit [5'-(TTA GGG TTA GGG)-3']. A linear fluorescence quenching ratio was obtained in 5-1000 pM of telomeric DNA units by adjusting the amount of FAM-modified probe. A PCR-free telomerase activity assay using this FRET-based method could be applied to ?400 HeLa cells per ?L. This assay represents a novel technique for initial screenings of cancer diagnosis and is a facile method for quantifying telomeric DNA or other tandem repeat sequences. PMID:24362853

  1. Sensitive iodate sensor based on fluorescence quenching of gold nanocluster.

    PubMed

    Li, Ruiping; Xu, Pingping; Fan, Jun; Di, Junwei; Tu, Yifeng; Yan, Jilin

    2014-05-27

    In this report we described a highly selective and sensitive iodate sensor. Due to its interaction with fluorescent gold nanoclusters, iodate was capable of oxidizing and etching gold core of the nanoclusters, resulting in fluorescence quenching. Furthermore, it was found that extra iodide ion could enhance this etching process, and even a small amount of iodate could lead to significant quenching. Under an optimized condition, linear relationship between the iodate concentration and the fluorescence quenching was obtained in the range 10 nM-1 ?M. The developed iodate sensor was found selective and capable of detecting iodate as low as 2.8 nM. The sensor was then applied for the analysis of iodate in real sample and satisfactory recoveries were obtained. PMID:24832998

  2. Development of Isotope Analysis Based on Laser Induced Fluorescence

    SciTech Connect

    Sakai, T.; Watanabe, K.; Uritani, A. [Department of Materials, Physics and Energy Engineering, Nagoya University (Japan); Tomita, H.; Iguchi, T. [Department of Quantum Engineering, Nagoya University (Japan)

    2009-03-17

    We have proposed Laser Induced Fluorescence analysis using Doppler Shift of laser ablated atoms for Isotope Analysis (LIF-DS-IA). This isotope analysis is expected to have a small mass discrimination effect because the detection target is fluorescence photons instead of ions, which distort the measured isotope ratio by the space charge effect. We demonstrate this technique to be feasible through the model calculations. We experimentally confirmed the fundamental behavior in LIF-DS-IA that the shift in the irradiating laser frequency corresponds to that of peak position in the time domain LIF spectra. The reason of poor mass resolution in the present system was considered to be inadequate definition in the field of view of the fluorescence detector.

  3. Exciton energy transfer-based quantum dot fluorescence sensing array: "chemical noses" for discrimination of different nucleobases.

    PubMed

    Liu, Jianbo; Li, Gui; Yang, Xiaohai; Wang, Kemin; Li, Li; Liu, Wei; Shi, Xing; Guo, Yali

    2015-01-20

    A novel exciton energy transfer-based fluorescence sensing array for the discrimination of different nucleobases was developed through target nucleobase-triggered self-assembly of quantum dots (QDs). Four QD nanoprobes with different ligand receptors, including mercaptoethylamine, N-acetyl-l-cysteine, 2-dimethyl-aminethanethiol, and thioglycolic acid, were created to detect and identify nucleobase targets. These QDs served as both selective recognition scaffolds and signal transduction elements for a biomolecule target. The extent of particle assembly, induced by the analyte-triggered self-assembly of QDs, led to an exciton energy transfer effect between interparticles that gave a readily detectable fluorescence quenching and distinct fluorescence response patterns. These patterns are characteristic for each nucleobase and can be quantitatively differentiated by linear discriminate analysis. Furthermore, a fingerprint-based barcode was established to conveniently discriminate the nucleobases. This pattern sensing was successfully used to identify nucleobase samples at unknown concentrations and five rare bases. In this "chemical noses" strategy, the robust characteristics of QD nanoprobes, coupled with the diversity of surface functionality that can be readily obtained using nanoparticles, provides a simple and label-free biosensing approach that shows great promise for biomedical applications. PMID:25495103

  4. Fluorescence-Based Sensor for Monitoring Activation of Lunar Dust

    NASA Technical Reports Server (NTRS)

    Wallace, William T.; Jeevarajan, Antony S.

    2012-01-01

    This sensor unit is designed to determine the level of activation of lunar dust or simulant particles using a fluorescent technique. Activation of the surface of a lunar soil sample (for instance, through grinding) should produce a freshly fractured surface. When these reactive surfaces interact with oxygen and water, they produce hydroxyl radicals. These radicals will react with a terephthalate diluted in the aqueous medium to form 2-hydroxyterephthalate. The fluorescence produced by 2-hydroxyterephthalate provides qualitative proof of the activation of the sample. Using a calibration curve produced by synthesized 2-hydroxyterephthalate, the amount of hydroxyl radicals produced as a function of sample concentration can also be determined.

  5. Development of a radiative transport based, fluorescence-enhanced, frequency-domain small animal imaging system 

    E-print Network

    Rasmussen, John C.

    2009-05-15

    transport based forward model for prediction of time-dependent propagation of photons in small, non-diffuse volumes, and an algorithm which utilizes the forward model to reconstruct fluorescent yields from air/tissue boundary measurements. The major...

  6. Switching properties of fluorescent photochromic poly(methyl methacrylate) with spironaphthoxazine and D-?-A type pyran-based fluorescent dye

    NASA Astrophysics Data System (ADS)

    Lee, Eun-Mi; Gwon, Seon-Young; Son, Young-A.; Kim, Sung-Hoon

    2012-02-01

    Fluorescent photochromic poly(methyl methacrylate) (PMMA) with spironaphthoxazine (SPO) and D-?-A type pyran-base fluorescent dye as a fluorophore was synthesized by typical free radical copolymerization. The poly(MMA- co-SPO- co-fluorophore) in both solution and solid film exhibited excellent photoregulated fluorescence switching behavior and reversible modulation of fluorescence intensity using alternating irradiation with UV and visible light. The poly(MMA- co-SPO- co-fluorophore) also showed viscosity and conductivity switching behaviors along with photoresponse.

  7. A simple one-step method for preparation of fluorescent carbon nanospheres and the potential application in cell organelles imaging.

    PubMed

    Ruan, Shaobo; Zhu, Biyue; Zhang, Huajin; Chen, Jiantao; Shen, Shun; Qian, Jun; He, Qin; Gao, Huile

    2014-05-15

    Highly fluorescent carbon nanospheres with a quantum yield of 17.6% have been prepared by a one-step method with hydrothermal treatment of spider silk. Due to the high photostability, low toxicity and well blood compatibility, these carbon nanospheres could be used as an excellent probes for cancer cell imaging. PMID:24655824

  8. Cellular discrimination based on spectral analysis of instrinic fluorescence

    Microsoft Academic Search

    G. R. Goddard; J. P. Houston; J. C. Martin; S. W. Graves; J. P. Freyer

    2008-01-01

    The increasing need for highly polychromatic approaches to flow cytometry, coupled with rapid technological advances, have driven the design and implementation of commercial instruments that measure up to 19 parameters using multiple lasers for excitation, an intricate optical filter\\/mirror arrangement, and analysis using fluorescence compensation approaches. Although such conventional multiparameter flow cytometers have proven highly successful, there are several types

  9. Development of a Green Fluorescent Protein-Based Laboratory Curriculum

    ERIC Educational Resources Information Center

    Larkin, Patrick D.; Hartberg, Yasha

    2005-01-01

    A laboratory curriculum has been designed for an undergraduate biochemistry course that focuses on the investigation of the green fluorescent protein (GFP). The sequence of procedures extends from analysis of the DNA sequence through PCR amplification, recombinant plasmid DNA synthesis, bacterial transformation, expression, isolation, and…

  10. GaAs-based integrated fluorescence bio-sensors: Progress towards high rejection of laser excitation light

    Microsoft Academic Search

    Thomas D. O'Sullivan; Elizabeth Munro; Ofer Levi; James S. Harris

    2008-01-01

    We demonstrate progress towards a GaAs-based integrated fluorescence bio-sensor capable of rivaling the performance of large-format fluorescence imaging systems by using a dielectric stack to filter the excitation light.

  11. Light-emitting diode and laser fluorescence-based devices in detecting occlusal caries

    Microsoft Academic Search

    Jonas A. Rodrigues; Isabel Hug; Klaus W. Neuhaus; Adrian Lussi

    2011-01-01

    The aim of this study was to assess the performance of two light-emitting diode (LED)- and two laser fluorescence-based devices in detecting occlusal caries in vitro. Ninety-seven permanent molars were assessed twice by two examiners using two LED- (Midwest Caries - MID and VistaProof - VP) and two laser fluorescence-based (DIAGNOdent 2095 - LF and DIAGNOdent pen 2190 - LFpen)

  12. A new boronic acid fluorescent sensor based on fluorene for monosaccharides at physiological pH

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, Rahman; Mohadjerani, Maryam; Pooryousef, Mona; Eslami, Abbas; Emami, Saeed

    2015-06-01

    Fluorescent boronic acids are very useful fluorescent sensor for detection of biologically important saccharides. Herein we synthesized a new fluorene-based fluorescent boronic acid that shows significant fluorescence changes upon addition of saccharides at physiological pH. Upon addition of fructose, sorbitol, glucose, galactose, ribose, and maltose at different concentration to the solution of 7-(dimethylamino)-9,9-dimethyl-9H-fluoren-2-yl-2-boronic acid (7-DMAFBA, 1), significant decreases in fluorescent intensity were observed. It was found that this boronic acid has high affinity (Ka = 3582.88 M-1) and selectivity for fructose over glucose at pH = 7.4. The sensor 1 showed a linear response toward D-fructose in the concentrations ranging from 2.5 × 10-5 to 4 × 10-4 mol L-1 with the detection limit of 1.3 × 10-5 mol L-1.

  13. Selective recognition of Ni2+ ion based on fluorescence enhancement chemosensor

    NASA Astrophysics Data System (ADS)

    Ganjali, M. R.; Hosseini, M.; Motalebi, M.; Sedaghat, M.; Mizani, F.; Faridbod, F.; Norouzi, P.

    2015-04-01

    A new enhancing fluorescent chemosensor was introduced for selective and sensitive determination of nickel ions based on 2-(1-H-benzo[d]imidazol-2yl)-N-phenyl hydrazine carbothioamide (L). L has an intrinsic fluorescent emission which enhances in presence of nickel ions in CH3CN/H2O (70:30, v/v) solution. The fluorescence enhancement of L is attributed to a 1:1 complex formation between L and Ni2+ ion which has been used for selective detection of Ni2+ ion. At the optimum conditions, the fluorescence intensity of L at 352 nm enhances linearly by the concentration of nickel ion from 1.6 × 10-5 to 1.6 × 10-7 M and detection limit of 7.9 × 10-8 M. The new fluorescent probe exhibited high selectivity to Ni2+ ion over the other common mono, di-and trivalent cations.

  14. Discrimination between streptavidin and avidin with fluorescent affinity-based probes.

    PubMed

    Sun, Qian; Tian, Haiyu; Qu, Haoran; Sun, Deheng; Chen, Zhuo; Duan, Liping; Zhang, Weibing; Qian, Junhong

    2015-06-15

    Two biotinylated coumarin-based fluorescent probes SPS3 and RC3 were designed for differentiating between structurally similar proteins streptavidin (SA) and avidin (AV). A substituted phenyl group is introduced onto SPS3, which may quench the fluorescence through twist intramolecular charge transfer (TICT). The fluorescence of SPS3 is turned on, by restraining the TICT process, when the fluorophore is buried at the surface of SA. RC3 is constructed by incorporating a biotin molecule to a coumarin fluorophore through a 4-atom spacer. The fluorescence intensity of RC3 is enhanced significantly when its fluorophore enters into the less polar binding pocket of AV. SPS3 and RC3 could be applied in distinguishing between SA and AV as well as in fluorescence imaging of biotin receptor over-expressed Hela cells. PMID:25985268

  15. The development of chlorophyll-based markers in poultry diets to aid detection of fluorescent fecal contamination.

    PubMed

    Lee, M R F; Leemans, D; Theobald, V J; Fleming, H R; Gay, A P

    2013-12-01

    Incidents of foodborne illness associated with consuming undercooked or raw chicken are often linked to 2 causative pathogens: Campylobacter spp. or Salmonella spp. Numerous studies have shown that contamination of carcasses results when pathogens are transferred from the intestinal tract or fecal material on feet and feathers to the dressed carcass. Ultraviolet spectral imaging to detect surface fecal and ingesta contamination on poultry carcasses may provide a solution to aid detection. However, poultry diets do not provide sufficiently high levels of natural fluorophores for this system to be reliable. This study investigated the potential of chlorophyll-based feed additives to improve fluorescence of the feces and narrow the excitation and emission wavelengths to aid in the development of a simple visualization system. Twenty-four hens (Gallus gallus domesticus) were allocated at random to 1 of 4 treatments: control (C, no marker), Zn chlorophyllin, Mg chlorophyllin, or Fe chlorophyllin. All markers were incorporated into mash before pelleting at a rate of 1 g/kg of DM. The experiment consisted of two 4 × 4 Latin squares with each period consisting of 2 wk. Feces were collected and extracted in acetone:water (50:50; vol/vol) with fecal fluorescence emission spectra determined using a Jasco FP-6200 Spectrofluorometer with excitation at 382 nm. A main peak evolved at wavelength 670 nm with the total area under the peak used as fluorescence intensity. Following 7 d of marker supplementation, the 3 markers improved the fluorescence intensity by ×14.8, 12.8, and 6.9 for Fe, Mg, and Zn chlorophyllin, respectively, compared with the control. The addition of feces containing Mg chlorophyllin to chicken carcass increased detection of the feces compared with feces with no marker. Also, due to the plain background of chicken skin, a simple image at 675 nm with appropriate thresholds would allow detection of contaminated carcasses at the current slaughter line speed without the need of expensive hyperspectral imaging. PMID:24235236

  16. Highly sensitive fluorescent probe for clenbuterol hydrochloride detection based on its catalytic oxidation of eosine Y by NaIO4.

    PubMed

    Liu, Jiaming; Liu, Zhen-bo; Huang, Qitong; Lin, Chang-Qing; Lin, Xiaofeng

    2014-09-01

    A highly sensitive fluorescent probe for clenbuterol hydrochloride (CLB) detection has been first designed based on its catalytic effect on NaIO4 oxidating eosine Y (R). And this environment-friendly, simple, rapid, selective and sensitive fluorescent probe has been utilized to detect CLB in the practical samples with the results consisting with those obtained by GC/MS. The structures of R and CLB were characterized by infrared spectra. The mechanism of the proposed assay for the detection of CLB was also discussed. PMID:25155629

  17. Fluorescence detection of trace PCB101 based on PITC immobilized on porous AAO membrane.

    PubMed

    Wang, Meiling; Meng, Guowen; Huang, Qing; Li, Mingtao; Li, Zhongbo; Tang, Chaolong

    2011-01-21

    A sensitive and selective fluorescent membrane for rapid detection of trace 2,2',4,5,5'-pentachlorinated biphenyl (PCB101) has been achieved by immobilizing the fluorophore phenyl isothiocyanate (PITC) onto porous anodic aluminium oxide (AAO) membrane (denoted as PITC@AAO). The fluorescence of the PITC@AAO membrane is obviously enhanced after titrating the analyte PCB101 into the membrane, being ascribed to the halogen-bonding interaction between the fluorophore PITC and the analyte PCB101. The fluorescence intensity increases with the PCB101 concentration in the low range below 1 ppm, and there exists an approximate linear relationship between the relative fluorescence intensity and the PCB101 concentration in the low range of 1-6 ppb. Moreover, the PITC@AAO membrane shows good selectivity; for example, it is insensitive to common structural analogs (polychlorinated aromatics). The mechanisms of the fluorescence enhancement and the better sensitivity and selectivity of the PITC@AAO membrane to PCB101 than that of PITC/n-hexane solution are also discussed. This work demonstrates that trace (in ppb range) PCBs can be detected by simple fluorescence measurement. PMID:21042607

  18. Soft nanomaterial-based targeting polymersomes for near-infrared fluorescence multispectral in vivo imaging.

    PubMed

    Li, Zuhong; Wu, Liyuan; Hu, Peiran; Han, Sihai; Zhang, Tao; Fan, Hongliang; Jin, Wei; Jin, Qinhan; Mu, Ying

    2012-11-21

    We report here the soft nanomaterial-based targeting polymersomes for near-infrared (NIR) fluorescence imaging to carry out in vivo tumor detection. Two polymersome-based NIR fluorescent probes were prepared through the self-assembly of amphiphilic block copolymers, poly(butadiene-b-ethylene oxide) (PEO-b-PBD). Each of them was encapsulated with distinct hydrophobic near-infrared dyes (DiD and DiR) and modified with different targeting ligands (anti-CEA antibody and anti-EGFR antibody), respectively. After simultaneous injection of these two probes into the tumor-bearing mice via tail vein, multispectral near-infrared fluorescence images were obtained. The results indicate that both probes are successfully directed to the tumor foci, where two distinguishable fluorescent signals were detected through the unmixed fluorescence images. By taking advantage of two targeting polymersome-based probes with distinct fluorescent features, the proposed multispectral near-infrared fluorescence imaging method can greatly improve the specificity and accuracy for in vivo tumor detection. PMID:23069779

  19. Soft nanomaterial-based targeting polymersomes for near-infrared fluorescence multispectral in vivo imaging

    NASA Astrophysics Data System (ADS)

    Li, Zuhong; Wu, Liyuan; Hu, Peiran; Han, Sihai; Zhang, Tao; Fan, Hongliang; Jin, Wei; Jin, Qinhan; Mu, Ying

    2012-10-01

    We report here the soft nanomaterial-based targeting polymersomes for near-infrared (NIR) fluorescence imaging to carry out in vivo tumor detection. Two polymersome-based NIR fluorescent probes were prepared through the self-assembly of amphiphilic block copolymers, poly(butadiene-b-ethylene oxide) (PEO-b-PBD). Each of them was encapsulated with distinct hydrophobic near-infrared dyes (DiD and DiR) and modified with different targeting ligands (anti-CEA antibody and anti-EGFR antibody), respectively. After simultaneous injection of these two probes into the tumor-bearing mice via tail vein, multispectral near-infrared fluorescence images were obtained. The results indicate that both probes are successfully directed to the tumor foci, where two distinguishable fluorescent signals were detected through the unmixed fluorescence images. By taking advantage of two targeting polymersome-based probes with distinct fluorescent features, the proposed multispectral near-infrared fluorescence imaging method can greatly improve the specificity and accuracy for in vivo tumor detection.

  20. Fluorescent Protein-Based Methods for On-Plate Screening of Gene Insertion

    PubMed Central

    Wong, Stanley S. C.; Truong, Kevin

    2010-01-01

    Background Unlike the commonly used method of blue-white screening for gene insertion, a fluorescent protein-based screening method offers a gain-of-function screening process without using any co-factors and a gene fusion product with a fluorescent protein reporter that is further useful in cell imaging studies. However, complications related to protein-folding efficiencies of the gene insert in fusion with fluorescent protein reporters prevent effective on-plate bacterial colony selection leading to its limited use. Methodology/Principal Findings Here, we present three methods to tackle this problem. Our first method promotes the folding of the gene insert by using an N-terminal protein such as calmodulin that is well folded and expressed. Under this method, fluorescence was increased more than 30x over control allowing for enhanced screening. Our second method creates a fluorescent protein that is N-terminal to the gene upon insertion, thereby reducing the dependency of the fluorescent protein reporter on the folding of the gene insert. Our third method eliminates any dependence of the fluorescent protein reporter on the folding of the gene insert by using a stop and start sequence for protein translation. Conclusions/Significance The three methods together will expand the usefulness of fluorescence on-plate screening and offer a powerful alternative to blue-white screening. PMID:21170317

  1. Two simple designs for surface-plasmon-resonance-based sensing

    NASA Astrophysics Data System (ADS)

    Kobe, Andrea; Mozina, Janez I.

    1999-12-01

    Surface plasmon resonance spectroscopy is becoming an increasingly important technique in biotechnology and chemical sensing. We present two simple, low cost, high sensitivity devices. The first is laser based mechanical implementation of a Kretschmann setup. Angle sweep is realized in two stages: step motor is used for coarse angle setting, and continuous angle sweep is achieved with a mirror on a floppy disk drive and a cylindrical lens setup. A single detector with AD converter defines resolution of the device through its sampling speed and dynamic range, so high sensitivity can be achieved. Sensor probes are metal- coated microscope slides and sample volume is temperature controlled. Second devices is a disposable cuvette for use in a VIS spectrometer. Specially designed monolithic polycarbonate block provides the required optical path and appropriate incidence angle on a thin metal film, deposited on the block. No equipment is necessary and the cuvette can be used within special cell, such as temperature controlled vessel. Device is also discussed in view of a low cost fiberoptic implementation. Some experimental results are presented to prove the applicability of devices. Disadvantages of technical solutions, used in devices, are also taken into consideration.

  2. A Fluorescence-Based Assay for Measuring the Redox Potential of 5-Lipoxygenase Inhibitors

    PubMed Central

    Lee, Sangchul; Park, Youngsam; Kim, Junghwan; Han, Sung-Jun

    2014-01-01

    The activities and side effects of 5-lipoxygenase (5-LO) inhibitors can be predicted by identifying their redox mechanisms. In this study, we developed a fluorescence-based method to measure the redox potential of 5-LO inhibitors and compared it to the conventional, absorbance-based method. After the pseudo-peroxidase reaction, the amount of remaining lipid peroxide was quantified using the H2DCFDA (2?,7?-dichlorodihydrofluorescein diacetate) fluorescence dye. Our method showed large signal windows and provided comparable redox potential values. Importantly, the redox mechanisms of known inhibitors were accurately measured with the fluorescence assay, whereas the conventional, absorbance-based method showed contradictory results. Our findings suggest that our developed method is a better alternative for classifying the redox potential of 5-LO inhibitors, and the fluorescence assay can be effectively used to study the mechanisms of action that are related to redox cycling. PMID:24498359

  3. Highly sensitive naphthalimide-based fluorescence polarization probe for detecting cancer cells.

    PubMed

    Jia, Ti; Fu, Congying; Huang, Chusen; Yang, Haotian; Jia, Nengqin

    2015-05-13

    Fluorescence polarization (FP)-based signal is a self-referencing fluorescence signal, and it is less dependent on dye concentration and environmental interferences, which makes FP measurement an attractive alternative sensing technology to fluorescence intensity-based detection. However, most of the fluorescence polarization probes were constructed by introducing fluorescein, rhodamine, and cyanine dyes, which have relatively shorter excited-state lifetimes compared with BODIPY and naphthalimide dyes. Herein, a first naphthalimide based fluorescence polarization probe (BIO) was designed and synthesized for selective and direct detection of cancer cells. The relatively longer excited-state lifetimes and high photostability of naphthalimide makes BIO more sensitive and accuracy in quantitative determination of HeLa cells in homogeneous solution without cell lysis and further separation steps. The detection limit of BIO for HeLa cells was about 85 cells mL(-1), the linear range was from 2.5 × 10(2) cells mL(-1) to 1 × 10(6) cells mL(-1) and the response time is no more than 25 min. Moreover, due to the relatively high photostability of naphthalimide, BIO was particularly suitable for live cell imaging under continuous irradiation with confocal microscopy, and the specific interaction of BIO with CD44-overexpressing cell lines was clearly visualized. Importantly, this BIO based sensing platform offers a direct and real-time tool for cancer cell diagnosis when complemented with the use of naphthalimide-based fluorescence polarization probe. PMID:25898141

  4. Dynamic Characterization of a UV Fluorescent Lamp

    Microsoft Academic Search

    Koksal Erenturk

    2008-01-01

    Dynamic modeling of an ultraviolet (UV) fluorescent lamp has been addressed in this paper. Based on a recently developed lamp model, a semiempirical modeling technique has been applied for dynamic modeling of a UV fluorescent lamp. In the modeling stage, simple electrical measurements have been used. In the proposed mathematical model, model parameters have been determined from electrical voltage and

  5. Novel and remarkable enhanced-fluorescence system based on gold nanoclusters for detection of tetracycline.

    PubMed

    Yang, Xiaoming; Zhu, Shanshan; Dou, Yao; Zhuo, Yan; Luo, Yawen; Feng, Yuanjiao

    2014-05-01

    Tetracycline and Eu(3+), while coexisting, usually appear as a complex by chelating. This complex shows low fluorescence intensity, leading to its limitation of analytical goals. Gold nanoclusters (AuNCs), emerging as novel nano-material, are attracting increasing attentions in multiple fields. Herein, gold nanoclusters first function as a fluorescence-enhanced reagent rather than a conventional fluorescent-probe, and a dramatic enhanced-fluorescence system was built based on Eu(3+)-Tetracycline complex (EuTC) by introducing gold nanoclusters. Simultaneously, three types of gold nanoclusters were employed for exploring various conditions likely affecting the system, which demonstrate that no other gold nanoclusters than DNA-templated gold nanoclusters enormously caused fluorescence-enhancement of EuTC. Moreover, this enhanced-fluorescence system permitted available detection of tetracycline (TC) in a linear range of 0.01-5 ?M, with a detection limit of 4 nM at a signal-to-noise ratio of 3. Significantly, the practicality of this method for detection of TC in human urine and milk samples was validated, demonstrating its advantages of simplicity, sensitivity and low cost. Interestingly, this system described here is probably promising for kinds of applications based on its dramatically enhanced-fluorescence. PMID:24720959

  6. Label free selective detection of estriol using graphene oxide-based fluorescence sensor

    NASA Astrophysics Data System (ADS)

    Kushwaha, H. S.; Sao, Reshma; Vaish, Rahul

    2014-07-01

    Water-soluble and fluorescent Graphene oxide (GO) is biocompatible, easy, and economical to synthesize. Interestingly, GO is also capable of quenching fluorescence. On the basis of its fluorescence and quenching abilities, GO has been reported to serve as an energy acceptor in a fluorescence resonance energy transfer (FRET) sensor. GO-based FRET biosensors have been widely reported for sensing of proteins, nucleic acid, ATP (Adenosine triphosphate), etc. GO complexes with fluorescent dyes and enzymes have been used to sense metal ions. Graphene derivatives have been used for sensing endocrine-disrupting chemicals like bisphenols and chlorophenols with high sensitivity and good reproducibility. On this basis, a novel GO based fluorescent sensor has been successfully designed to detect estriol with remarkable selectivity and sensitivity. Estriol is one of the three estrogens in women and is considered to be medically important. Estriol content of maternal urine or plasma acts as an important screening marker for estimating foetal growth and development. In addition, estriol is also used as diagnostic marker for diseases like breast cancer, osteoporosis, neurodegenerative and cardiovascular diseases, insulin resistance, lupus erythematosus, endometriosis, etc. In this present study, we report for the first time a rapid, sensitive with detection limit of 1.3 nM, selective and highly biocompatible method for label free detection of estriol under physiological conditions using fluorescence assay.

  7. Fluorescence-based video profile beam diagnostics: Theory and experience

    SciTech Connect

    Sandoval, D.; Gilpatrick, D.; Shinas, M.; Garcia, R.; Yuan, V.; Zander, M.

    1994-05-01

    Inelastic collisions between accelerated particles and residual gas in the accelerator vessel can cause the residual gas to fluoresce. The gas fluorescence intensity is proportional to the current density of the particle beam. This process provides the foundation for a video diagnostic system to measure the profile and position of accelerated particle beams. This, in fact, has proven to be a useful diagnostic at several installations. This paper describes the light production process resulting from beam -- residual gas interactions and gives formulas for estimating the beam radiance for various conditions. Ground Test Accelerator (GTA) radiance calculations will be used as an example. In addition, measurement experiences with the GTA video diagnostics system will be discussed.

  8. Photosystem II Does Not Possess a Simple Excitation Energy Funnel: Time-Resolved Fluorescence Spectroscopy Meets Theory

    PubMed Central

    2013-01-01

    The experimentally obtained time-resolved fluorescence spectra of photosystem II (PS II) core complexes, purified from a thermophilic cyanobacterium Thermosynechococcus vulcanus, at 5–180 K are compared with simulations. Dynamic localization effects of excitons are treated implicitly by introducing exciton domains of strongly coupled pigments. Exciton relaxations within a domain and exciton transfers between domains are treated on the basis of Redfield theory and generalized Förster theory, respectively. The excitonic couplings between the pigments are calculated by a quantum chemical/electrostatic method (Poisson-TrEsp). Starting with previously published values, a refined set of site energies of the pigments is obtained through optimization cycles of the fits of stationary optical spectra of PS II. Satisfactorily agreement between the experimental and simulated spectra is obtained for the absorption spectrum including its temperature dependence and the linear dichroism spectrum of PS II core complexes (PS II-CC). Furthermore, the refined site energies well reproduce the temperature dependence of the time-resolved fluorescence spectrum of PS II-CC, which is characterized by the emergence of a 695 nm fluorescence peak upon cooling down to 77 K and the decrease of its relative intensity upon further cooling below 77 K. The blue shift of the fluorescence band upon cooling below 77 K is explained by the existence of two red-shifted chlorophyll pools emitting at around 685 and 695 nm. The former pool is assigned to Chl45 or Chl43 in CP43 (Chl numbering according to the nomenclature of Loll et al. Nature2005, 438, 1040) while the latter is assigned to Chl29 in CP47. The 695 nm emitting chlorophyll is suggested to attract excitations from the peripheral light-harvesting complexes and might also be involved in photoprotection. PMID:23537277

  9. Computed tomography based spectral imaging for fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Ford, Bridget Kathleen

    Multispectral imaging has been used for decades in remote sensing to enhance the classification, discrimination and characterization of materials. Only recently has this same technology been similarly applied to fixed biological samples in cytogenetics, pathology and medicine. A further extension to in vivo studies is often limited by the low levels of associated fluorescence as well as the increased temporal resolution required to analyze physiological changes. In addition, the cellular response to a specific agonist is often heterogeneous across the cellular field requiring a combination of sufficient spatial and temporal resolutions. A computed tomography imaging spectrometer (CTIS) has been developed which overcomes these limitations by simultaneously collecting extended range spectral information (470--740 nm, 5 nm sampling) across a 2-D field of view (200 mum x 200 mum, 0.96 mum sampling). The CTIS uses a computer generated hologram to produce a 5 x 5 array of images with differing amounts and directions of dispersion. This set of images allows the 3-D signal (x, y, lambda) from a fluorescent sample to be mapped onto a 2-D detector array. In this way, the full spectral and spatial information is acquired for a 2-D cellular field during a single integration time (presently 2 sec for biological specimens). The CTIS's design, calibration, and underlying theory are described in detail. In addition, the capability of the CTIS to simultaneously collect the fluorescence emission of multiple fluorophores across a 2-D cellular field is demonstrated. Specifically, the combined spectral variations of seminapthorhodafluor-I and enhanced green fluorescent protein were followed in rat insulinoma cells in order to extend the linear range of intracellular pH detection.

  10. A dansyl-rhodamine ratiometric fluorescent probe for Hg2+ based on FRET mechanism.

    PubMed

    Xie, Puhui; Guo, Fengqi; Wang, Lingyu; Yang, Sen; Yao, Denghui; Yang, Guoyu

    2015-03-01

    Based on resonance energy transfer (FRET) from dansyl to rhodamine 101, a new fluorescent probe (compound 1) containing rhodamine 101 and a dansyl unit was synthesized for detecting Hg(2+) through ratiometric sensing in DMSO aqueous solutions. This probe shows a fast, reversible and selective response toward Hg(2+) in a wide pH range. Hg(2+) induced ring-opening reactions of the spirolactam rhodamine moiety of 1, leading to the formation of fluorescent derivatives that can serve as the FRET acceptors. Very large stokes shift (220 nm) was observed in this case. About 97-fold increase in fluorescence intensity ratio was observed upon its binding with Hg(2+). PMID:25597044

  11. Temperature-modulated fluorescence tomography based on both concentration and lifetime contrast

    PubMed Central

    Lin, Yuting; Kwong, Tiffany C.; Bolisay, Linden; Gulsen, Gultekin

    2012-01-01

    Abstract. It is challenging to image fluorescence objects with high spatial resolution in a highly scattering medium. Recently reported temperature-sensitive indocyanine green-loaded pluronic nanocapsules can potentially alleviate this problem. Here we demonstrate a frequency-domain temperature-modulated fluorescence tomography system that could acquire images at high intensity-focused ultrasound resolution with use of these nanocapsules. The system is experimentally verified with a phantom study, where a 3-mm fluorescence object embedded 2 cm deep in a turbid medium is successfully recovered based on both intensity and lifetime contrast. PMID:22612130

  12. Temperature-modulated fluorescence tomography based on both concentration and lifetime contrast.

    PubMed

    Lin, Yuting; Kwong, Tiffany C; Bolisay, Linden; Gulsen, Gultekin

    2012-05-01

    It is challenging to image fluorescence objects with high spatial resolution in a highly scattering medium. Recently reported temperature-sensitive indocyanine green-loaded pluronic nanocapsules can potentially alleviate this problem. Here we demonstrate a frequency-domain temperature-modulated fluorescence tomography system that could acquire images at high intensity-focused ultrasound resolution with use of these nanocapsules. The system is experimentally verified with a phantom study, where a 3-mm fluorescence object embedded 2 cm deep in a turbid medium is successfully recovered based on both intensity and lifetime contrast. PMID:22612130

  13. Temperature-modulated fluorescence tomography based on both concentration and lifetime contrast

    NASA Astrophysics Data System (ADS)

    Lin, Yuting; Kwong, Tiffany C.; Bolisay, Linden; Gulsen, Gultekin

    2012-05-01

    It is challenging to image fluorescence objects with high spatial resolution in a highly scattering medium. Recently reported temperature-sensitive indocyanine green-loaded pluronic nanocapsules can potentially alleviate this problem. Here we demonstrate a frequency-domain temperature-modulated fluorescence tomography system that could acquire images at high intensity-focused ultrasound resolution with use of these nanocapsules. The system is experimentally verified with a phantom study, where a 3-mm fluorescence object embedded 2 cm deep in a turbid medium is successfully recovered based on both intensity and lifetime contrast.

  14. Active, polymer-based composite material implementing simple shear 

    E-print Network

    Lee, Sang Jin

    2009-05-15

    A novel active material for controllable, high work density applications was designed, fabricated, analyzed, and tested. This active material uses a lens-shaped element to implement simple shear motion with gas pressure actuation. The lens element...

  15. Active, polymer-based composite material implementing simple shear

    E-print Network

    Lee, Sang Jin

    2009-05-15

    A novel active material for controllable, high work density applications was designed, fabricated, analyzed, and tested. This active material uses a lens-shaped element to implement simple shear motion with gas pressure actuation. The lens element...

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Red fluorescent proteins (RFPs) and RFP-based biosensors for neuronal imaging applications.

    PubMed

    Shen, Yi; Lai, Tiffany; Campbell, Robert E

    2015-07-01

    The inherent advantages of red-shifted fluorescent proteins and fluorescent protein-based biosensors for the study of signaling processes in neurons and other tissues have motivated the development of a plethora of new tools. Relative to green fluorescent proteins (GFPs) and other blue-shifted alternatives, red fluorescent proteins (RFPs) provide the inherent advantages of lower phototoxicity, lower autofluorescence, and deeper tissue penetration associated with longer wavelength excitation light. All other factors being the same, the multiple benefits of using RFPs make these tools seemingly ideal candidates for use in neurons and, ultimately, the brain. However, for many applications, the practical utility of RFPs still falls short of the preferred GFPs. We present an overview of RFPs and RFP-based biosensors, with an emphasis on their reported applications in neuroscience. PMID:26158012

  18. A dissolved oxygen sensor based on ruthenium fluorescence and u-shaped plastic optical fiber

    Microsoft Academic Search

    Fenghong Chu; Haiwen Cai; Ronghui Qu; Zujie Fang

    2007-01-01

    A dissolved oxygen sensor based on ruthenium(Ru) fluorescence and U-shape plastic optical fiber (POF) was described. Dichlorotris (1, 10-phenanthroline) ruthenium (II) was used as an oxygen indicator, which was coated on to the surface of a 1mm diameter U-shaped POF. Phase modulation technique is used to measure fluorescence lifetime. The phase difference between 100% and 0% dissolved oxygen is 1.78

  19. Room-temperature single-photon sources based on nanocrystal fluorescence in photonic/plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Lukishova, S. G.; Winkler, J. M.; Bissell, L. J.; Mihaylova, D.; Liapis, Andreas C.; Shi, Z.; Goldberg, D.; Menon, V. M.; Boyd, R. W.; Chen, G.; Prasad, P.

    2014-10-01

    Results are presented here towards robust room-temperature SPSs based on fluorescence in nanocrystals: colloidal quantum dots, color-center diamonds and doped with trivalent rare-earth ions (TR3+). We used cholesteric chiral photonic bandgap and Bragg-reflector microcavities for single emitter fluorescence enhancement. We also developed plasmonic bowtie nanoantennas and 2D-Si-photonic bandgap microcavities. The paper also provides short outlines of other technologies for room-temperature single-photon sources.

  20. Live spheroid formation recorded with light sheet-based fluorescence microscopy.

    PubMed

    Pampaloni, Francesco; Richa, Roli; Ansari, Nariman; Stelzer, Ernst H K

    2015-01-01

    We provide a detailed protocol for a three-dimensional long-term live imaging of cellular spheroids with light sheet-based fluorescence microscopy. The protocol allows the recording of all phases of spheroid formation in three dimensions, including cell proliferation, aggregation, and compaction. We employ the human hepatic cell line HepaRG transfected with the fusion protein H2B-GFP, i.e., a fluorescing histone. The protocol allows monitoring the effect of drugs or toxicants. PMID:25391793

  1. A fluorescence-based hydrolytic enzyme activity assay for quantifying toxic effects of Roundup® to Daphnia magna.

    PubMed

    Ørsted, Michael; Roslev, Peter

    2015-08-01

    Daphnia magna is a widely used model organism for aquatic toxicity testing. In the present study, the authors investigated the hydrolytic enzyme activity of D. magna after exposure to toxicant stress. In vivo enzyme activity was quantified using 15 fluorogenic enzyme probes based on 4-methylumbelliferyl or 7-amino-4-methylcoumarin. Probing D. magna enzyme activity was evaluated using short-term exposure (24-48 h) to the reference chemical K2 Cr2 O7 or the herbicide formulation Roundup®. Toxicant-induced changes in hydrolytic enzyme activity were compared with changes in mobility (International Organization for Standardization standard 6341). The results showed that hydrolytic enzyme activity was quantifiable as a combination of whole body fluorescence of D. magna and the fluorescence of the surrounding water. Exposure of D. magna to lethal and sublethal concentrations of Roundup resulted in loss of whole body enzyme activity and release of cell constituents, including enzymes and DNA. Roundup caused comparable inhibition of mobility and alkaline phosphatase activity with median effective concentration values at 20?°C of 8.7?mg active ingredient (a.i.)/L to 11.7?mg?a.i./L. Inhibition of alkaline phosphatase activity by Roundup was lowest at 14?°C and greater at 20?°C and 26?°C. The results suggest that the fluorescence-based hydrolytic enzyme activity assay (FLEA assay) can be used as an index of D. magna stress. Combining enzyme activity with fluorescence measurements may be applied as a simple and quantitative supplement for toxicity testing with D. magna. Environ Toxicol Chem 2015;34:1841-1850. © 2015 SETAC. PMID:25809520

  2. A fluorescent biosensing platform based on the polydopamine nanospheres intergrating with Exonuclease III-assisted target recycling amplification.

    PubMed

    Qiang, Weibing; Wang, Xi; Li, Wei; Chen, Xiang; Li, Hui; Xu, Danke

    2015-09-15

    Rapid, cost-effective, sensitive and specific analysis of biomolecules is important in the modern healthcare system. Here, a fluorescent biosensing platform based on the polydopamine nanospheres (PDANS) intergrating with Exonuclease III (Exo III) was developed. Due to the interaction between the ssDNA and the PDANS, the fluorescence of 6-carboxyfluorescein (FAM) labelled in the probe would been quenched by PDANS through FRET. While, in the present of the target DNA, the probe DNA would hybridize with the target DNA to form the double-strand DNA complex. Thus, Exo III could catalyze the stepwise removal of mononucleotides from 3'-terminus in the probe DNA, releasing the target DNA. As the FAM was released from the probe DNA, the fluorescence would no longer been quenched, led to the signal on. As one target DNA molecule could undergo a number of cycles to trigger the degradation of abundant probe DNA, Exo III-assisted target recycling would led to the amplification of the signal. The detection limit for DNA was 5pM, which was 20 times lower than that without Exo III. And the assay time was largely shortened due to the faster signal recovery kinetics. What is more, this target recycling strategy was also applied to conduct an aptamer-based biosensing platform. The fluorescence intensity was also enhanced for the assay of adenosine triphosphate (ATP). For the Exo III-assisted target recycling amplification, DNA and ATP were fast detected with high sensitivity and selectivity. This work provides opportunities to develop simple, rapid, economical, and sensitive biosensing platforms for biomedical diagnostics. PMID:25897884

  3. Comparison of fluorescence-based semi-automated genotyping of multiple microsatellite loci with autoradiographic techniques

    SciTech Connect

    Schwengel, D.A.; Jedlicka, A.E.; Levitt, R.C. [Johns Hopkins Medical Institutions, Baltimore, MD (United States)] [and others] [Johns Hopkins Medical Institutions, Baltimore, MD (United States); and others

    1994-07-01

    The practical application of highly efficient fluorescence-based methods for the semi-automated genotyping of polymerase chain reaction-based microsatellite markers will depend on the development of robust protocols that provide accurate and reproducible data. In the present report the authors compare the accuracy of a fluorescence-based protocol with a benchmark radiolabeling method that depends on a known sequence ladder or amplified DNA from reference individuals for sizing by autoradiography. Three microsatellite markers, IGF (mfd1), D4S174 (mfd 59), and D5S211 (mfd 154), with products overlapping in size were each labeled with a different fluorophore and run simultaneously with an internal size standard in a single electrophoretic lane. The size of each allele was compared for these markers by using both techniques for five larger CEPH families (884, 1331, 1333, and 1362). Of 462 possible alleles, four discrepancies (0.8%) were identified when the two approaches were compared. The authors conclude that the fluorescence-based protocol is at least as accurate as the standard radiolabeling technique since none of the sizing errors arose as a result of the fluorescence-based technique. They describe the adaptation of the fluorescence-based protocol to the simultaneous analysis of up to 24 microsatellite loci per electrophoretic lane. These highly accurate and efficient semi-automated techniques will be useful in high-resolution genomic analyses. 18 refs., 4 tabs., 3 figs.

  4. A fluorescence-based helicase assay: application to the screening of G-quadruplex ligands

    PubMed Central

    Mendoza, Oscar; Gueddouda, Nassima Meriem; Boulé, Jean-Baptiste; Bourdoncle, Anne; Mergny, Jean-Louis

    2015-01-01

    Helicases, enzymes that unwind DNA or RNA structure, are present in the cell nucleus and in the mitochondrion. Although the majority of the helicases unwind DNA or RNA duplexes, some of these proteins are known to resolve unusual structures such as G-quadruplexes (G4) in vitro. G4 may form stable barrier to the progression of molecular motors tracking on DNA. Monitoring G4 unwinding by these enzymes may reveal the mechanisms of the enzymes and provides information about the stability of these structures. In the experiments presented herein, we developed a reliable, inexpensive and rapid fluorescence-based technique to monitor the activity of G4 helicases in real time in a 96-well plate format. This system was used to screen a series of G4 structures and G4 binders for their effect on the Pif1 enzyme, a 5? to 3? DNA helicase. This simple assay should be adaptable to analysis of other helicases and G4 structures. PMID:25765657

  5. Fluorescence based cell counting in collagen monolayer cultures of primary hepatocytes.

    PubMed

    Priesnitz, C; Sperber, S; Garg, R; Orsini, M; Noor, F

    2014-11-26

    Accurate determination of cell number is essential for the quantitative description of biological processes. The changes should be related to a measurable reference e.g. in the case of cell culture, the viable cell number is a very valuable reference parameter. Indirect methods of cell number/viability measurements may have up to 10 % standard deviation. This can lead to undesirable large deviations in the analysis of "-omics" data as well as time course studies. Such data should be preferably normalized to the exact viable cell number at a given time to allow meaningful interpretation and understanding of the biological processes. Manual counting of cell number is very laborious and not possible in certain experimental setups. We therefore, developed a simple and reliable fluorescence based method with an accuracy of 95-98 % for the determination of the viable cell number in situ. We optimized the seeding cell densities for primary rat hepatocytes for optimal cell adhesion. This will help in efficient use of primary cells which are usually limited in availability. The method will be very useful in the application of "-omics" techniques, especially metabolome analysis where the specific rates of uptake/production of metabolites can be reliably calculated. PMID:25424145

  6. An in-situ fluorescence-based optical extensometry system for imaging mechanically loaded bone.

    PubMed

    Price, Christopher; Li, Wen; Novotny, John E; Wang, Liyun

    2010-06-01

    The application and quantification of well-controlled tissue strains is required for investigations into mechanisms of tissue adaptation within the musculoskeletal system. Although many commercial and custom extensometry systems exist for large biological samples, integrated loading/strain measurement for small samples is not as readily available. Advanced imaging modules such as laser scanning microscopy provide in situ, minimally invasive tools to probe cellular and molecular processes with high spatiotemporal resolution. Currently, a need exists to devise loading/strain measurement systems that can be integrated with such advanced imaging modules. We describe the development and validation of a fluorescence-based, optical extensometry system directly integrated within a confocal microscopy platform. This system allows in situ measurement of surface strain and is compatible with the direct imaging of cellular processes within small bone samples. This optical extensometry system can accurately and reproducibly measure physiologically relevant surface strains (200 to 3000 microstrain) in beams machined from various well-characterized materials, including bovine femoral cortex, and in intact murine tibia. This simple system provides a powerful tool to further our investigation of the relationships between mechanical loading, fluid and solute transport, and mechanosensation within the musculoskeletal system. PMID:20041487

  7. A Mechanism-Based Fluorescence Transfer Assay for Examining Ketosynthase Selectivity

    PubMed Central

    Prasad, Gitanjeli; Borketey, Lawrence S.; Lin, Tsung-Yi

    2014-01-01

    Since their discovery, polyketide synthases have received massive attention from researchers hoping to harness their potential as a platform for generating new and improved therapeutics. Despite significant strides toward this end, inherent specificites within the enzymes responsible for polyketide production have severely limited these efforts. We have developed a mechanism-based, fluorescence transfer assay for a key enzyme component of all polyketide synthases, the ketosynthase domain. As demonstrated, this method can be used with both ketosynthase-containing didomains and full modules. As proof of principle, the ketosynthase domain from module 6 of the 6-deoxyerythronolide synthase is examined for its ability to accept a variaty of simple thioester substrates. Consistent with its natural hexaketide substrate, we find that this ketosynthase prefers longer, ?-branched thioesters and its ability to distinguish these structural features is quite remarkable. Substrate electronics are also tested via a variety of p-substituted aromatic groups. In all, we expect this technique to find considerable use in the field of polyketide biosynthesis and engineering due to its extraordinary simplicity and very distinct visible readout. PMID:22806124

  8. A fluorescence-based helicase assay: application to the screening of G-quadruplex ligands.

    PubMed

    Mendoza, Oscar; Gueddouda, Nassima Meriem; Boulé, Jean-Baptiste; Bourdoncle, Anne; Mergny, Jean-Louis

    2015-06-23

    Helicases, enzymes that unwind DNA or RNA structure, are present in the cell nucleus and in the mitochondrion. Although the majority of the helicases unwind DNA or RNA duplexes, some of these proteins are known to resolve unusual structures such as G-quadruplexes (G4) in vitro. G4 may form stable barrier to the progression of molecular motors tracking on DNA. Monitoring G4 unwinding by these enzymes may reveal the mechanisms of the enzymes and provides information about the stability of these structures. In the experiments presented herein, we developed a reliable, inexpensive and rapid fluorescence-based technique to monitor the activity of G4 helicases in real time in a 96-well plate format. This system was used to screen a series of G4 structures and G4 binders for their effect on the Pif1 enzyme, a 5' to 3' DNA helicase. This simple assay should be adaptable to analysis of other helicases and G4 structures. PMID:25765657

  9. Autojoin: A Simple Rule Based Query Service for Complex Databases

    NASA Astrophysics Data System (ADS)

    Gaffney, N. I.; Gardner, L.; Brandt, M.

    Most databases used today are no longer flat. While the power of using these more complex data stores is well known, construction of queries can be quite a complex task. Currently this often requires detailed knowledge of the database structure and schema. As we move towards a VO paradigm, users cannot be expected to know the structure of databases, but will need to query them. Databases will need to provide query engines to complete queries automatically given only what the user wants to have returned and any qualifications they place on the query. For years StarView, a database query and data retrieval tool for the Space Telescope Science Institute, relied on a complex third party LISP-based program (QUICK) to construct valid SQL queries for the one database it could query. This limited our ability to support StarView as we could not easily add new rules to the system without completely rebuilding the query engine. Furthermore, QUICK did not have the ability to create SQL that would join tables in different databases (but hosted on the same server). Finally, the cost of upgrading to a new version of QUICK was prohibitively high. Our solution was to develop a rather simple database table driven Perl CGI program which is able to take as its input a skeleton SQL program. This may come from a program or other web page. In the query only the SELECT and user qualified WHERE clause are specified; no FROM or WHERE clause join information is included. The service then returns a fully qualified and syntactically correct query for the host database SQL program that can be used to get the information the user needs. Thus, an additional layer of abstraction for dealing with databases is created, freeing the user from having to know how tables are related in the database. In this paper we discuss the design and algorithm used to make Autojoin work as well as discuss how, when combined with a robust and searchable description of all the fields that can be publicly queried in the database, it allows users to tailor their questions to the database with ease and a high rate of success.

  10. Computed tomography-based spectral imaging for fluorescence microscopy.

    PubMed Central

    Ford, B K; Volin, C E; Murphy, S M; Lynch, R M; Descour, M R

    2001-01-01

    The computed tomography imaging spectrometer (CTIS) is a non-scanning instrument capable of simultaneously acquiring full spectral information (450-750 nm) from every position element within its field of view (75 microm x 75 microm). The current spatial and spectral sampling intervals of the spectrometer are 1.0 microm and 10 nm, respectively. This level of resolution is adequate to resolve signal responses from multiple fluorescence probes located within individual cells or different locations within the same cell. Spectral imaging results are presented from the CTIS combined with a commercial inverted fluorescence microscope. Results demonstrate the capability of the CTIS to monitor the spatiotemporal evolution of pH in rat insulinoma cells loaded with SNARF-1. The ability to analyze full spectral information for two-dimensional (x, y) images allows precise evaluation of heterogeneous physiological responses within cell populations. Due to low signal levels, integration times up to 2 s were required. However, reasonable modifications to the instrument design will provide higher system transmission efficiency with increased temporal and spatial resolution. Specifically, a custom optical design including the use of a larger format detector array is under development for a second-generation system. PMID:11159465

  11. Assessment of dental demineralization of yellow race based on fluorescence spectrum

    NASA Astrophysics Data System (ADS)

    Zhan, Zhenlin; Chen, Chuanguo; Li, Xuwei; Zhang, Xianzeng; Xie, Shusen

    2014-11-01

    The goal of this study was to evaluate the demineralization status at different acid-etch time based on fluorescence spectrum. Human molars in vitro of yellow race were cut into tooth sections and then they were immersed in 0.3% citric acid to simulate the oral natural demineralization. According to the acid-etch time, samples were randomly divided into three groups: I:20 min, II:40 min, and III:60 min. The normal untreated specimen was set as control group. The fluorescence spectra before and after treatment were measured and analyzed. The result showed that fluorescence spectrum could be efficiently used to monitor the demineralization status of human dental tissue. The relative fluorescence intensities of dental tissue excited respectively with 260, 330 and 400 nm decreased with the increase of acid-etch time, though there was no new constituent formed after demineralization.

  12. [Rapid recognition of common machine oils based on laser induced fluorescence].

    PubMed

    Liu, Xiao-hua; Chen, Si-ying; Zhang, Yin-chao; Guo, Pan; Chen, He; Mu, Tao-tao

    2014-08-01

    A rapid recognition method of common engine oils, based on the principle of laser induced fluorescence (LIF), is proposed in the present paper. A 355 nm ultraviolet laser is used to induce fluorescence emission of 9 kinds of common machine oil samples. In total 450 groups of fluorescence spectral data are collected, of which 360 groups of data are used for classification training and 90 sets of data for identification. It was found that the fluorescence spectra of engine oils are distinct from each other visibly. The rapid identification of 90 groups of data is realized by using clustering analysis combined with principal component analysis. The recognition rate could reach up to 97.8%. Experiment demonstrated that the fast identification of diverse engine oils could be realized by using LIF combined with multivariate analysis method. PMID:25474952

  13. [Rapid recognition of common machine oils based on laser induced fluorescence].

    PubMed

    Liu, Xiao-hua; Chen, Si-ying; Zhang, Yin-chao; Guo, Pan; Chen, He; Mu, Tao-tao

    2014-08-01

    A rapid recognition method of common engine oils, based on the principle of laser induced fluorescence (LIF), is proposed in the present paper. A 355 nm ultraviolet laser is used to induce fluorescence emission of 9 kinds of common machine oil samples. In total 450 groups of fluorescence spectral data are collected, of which 360 groups of data are used for classification training and 90 sets of data for identification. It was found that the fluorescence spectra of engine oils are distinct from each other visibly. The rapid identification of 90 groups of data is realized by using clustering analysis combined with principal component analysis. The recognition rate could reach up to 97.8%. Experiment demonstrated that the fast identification of diverse engine oils could be realized by using LIF combined with multivariate analysis method. PMID:25508731

  14. Static hyperspectral fluorescence imaging of viscous materials based on a linear variable filter spectrometer.

    PubMed

    Murr, Patrik J; Schardt, Michael; Koch, Alexander W

    2013-01-01

    This paper presents a low-cost hyperspectral measurement setup in a new application based on fluorescence detection in the visible (Vis) wavelength range. The aim of the setup is to take hyperspectral fluorescence images of viscous materials. Based on these images, fluorescent and non-fluorescent impurities in the viscous materials can be detected. For the illumination of the measurement object, a narrow-band high-power light-emitting diode (LED) with a center wavelength of 370 nm was used. The low-cost acquisition unit for the imaging consists of a linear variable filter (LVF) and a complementary metal oxide semiconductor (CMOS) 2D sensor array. The translucent wavelength range of the LVF is from 400 nm to 700 nm. For the confirmation of the concept, static measurements of fluorescent viscous materials with a non-fluorescent impurity have been performed and analyzed. With the presented setup, measurement surfaces in the micrometer range can be provided. The measureable minimum particle size of the impurities is in the nanometer range. The recording rate for the measurements depends on the exposure time of the used CMOS 2D sensor array and has been found to be in the microsecond range. PMID:24064604

  15. Antisense therapeutics: is it as simple as complementary base recognition?

    Microsoft Academic Search

    Sudhir Agrawal; Ekambar R Kandimalla

    2000-01-01

    Antisense oligonucleotides provide a simple and efficient approach for developing target-selective drugs because they can modulate gene expression sequence-specifically. Antisense oligonucleotides have also become efficient molecular biological tools to investigate the function of any protein in the cell. As the application of antisense oligonucleotides has expanded, multiple mechanisms of oligonucleotides have been characterized that impede their routine use. Here, we

  16. Development of a solid surface fluorescence-based sensing system for aluminium monitoring in drinking water

    Microsoft Academic Search

    J. F. García Reyes; P. Ortega Barrales; A. Molina Díaz

    2005-01-01

    A novel, single and robust solid surface fluorescence-based sensing device assembled in a continuous flow system has been developed for the determination of trace amounts of aluminium in water samples. The proposed method is based on the transient immobilization of the target species on an appropriate active solid sensing zone (C18 silica gel). The target species was the fluorogenic chelate,

  17. A SIMPLE based discontinuous Galerkin solver for steady incompressible flows

    NASA Astrophysics Data System (ADS)

    Klein, Benedikt; Kummer, Florian; Oberlack, Martin

    2013-03-01

    In this paper we present how the well-known SIMPLE algorithm can be extended to solve the steady incompressible Navier-Stokes equations discretized by the discontinuous Galerkin method. The convective part is discretized by the local Lax-Friedrichs fluxes and the viscous part by the symmetric interior penalty method. Within the SIMPLE algorithm, the equations are solved in an iterative process. The discretized equations are linearized and an equation for the pressure is derived on the discrete level. The equations obtained for each velocity component and the pressure are decoupled and therefore can be solved sequentially, leading to an efficient solution procedure. The extension of the proposed scheme to the unsteady case is straightforward, where fully implicit time schemes can be used. Various test cases are carried out: the Poiseuille flow, the channel flow with constant transpiration, the Kovasznay flow, the flow into a corner and the backward-facing step flow. Using a mixed-order formulation, i.e. order k for the velocity and order k-1 for the pressure, the scheme is numerically stable for all test cases. Convergence rates of k+1 and k in the L2-norm are observed for velocity and pressure, respectively. A study of the convergence behavior of the SIMPLE algorithm shows that no under-relaxation for the pressure is needed, which is in strong contrast to the application of the SIMPLE algorithm in the context of the finite volume method or the continuous finite element method. We conclude that the proposed scheme is efficient to solve the steady incompressible Navier-Stokes equations in the context of the discontinuous Galerkin method comprising hp-accuracy.

  18. Dynamics-Based Motion Synthesis by Simple Learning Control

    Microsoft Academic Search

    Petko Kiriazov

    2002-01-01

    Point-to-point motion of a humanoid agent (or any mobile creature) is considered as a composition of basic movements related to the degrees of freedom. With time\\/energy performance criteria, such movements can be synthesized by using simple control functions. Natural looking animation can be achieved employing even very simplified dynamics models. Their parameters can be estimated or identified using motion capture

  19. Use of Time-Resolved Fluorescence to Monitor Bioactive Compounds in Plant Based Foodstuffs.

    PubMed

    Lemos, M Adília; Sárniková, Katarína; Bot, Francesca; Anese, Monica; Hungerford, Graham

    2015-01-01

    The study of compounds that exhibit antioxidant activity has recently received much interest in the food industry because of their potential health benefits. Most of these compounds are plant based, such as polyphenolics and carotenoids, and there is a need to monitor them from the field through processing and into the body. Ideally, a monitoring technique should be non-invasive with the potential for remote capabilities. The application of the phenomenon of fluorescence has proved to be well suited, as many plant associated compounds exhibit fluorescence. The photophysical behaviour of fluorescent molecules is also highly dependent on their microenvironment, making them suitable probes to monitor changes in pH, viscosity and polarity, for example. Time-resolved fluorescence techniques have recently come to the fore, as they offer the ability to obtain more information, coupled with the fact that the fluorescence lifetime is an absolute measure, while steady state just provides relative and average information. In this work, we will present illustrative time-resolved measurements, rather than a comprehensive review, to show the potential of time-resolved fluorescence applied to the study of bioactive substances. The aim is to help assess if any changes occur in their form, going from extraction via storage and cooking to the interaction with serum albumin, a principal blood transport protein. PMID:26132136

  20. A Simple and Sensitive HPLC Method for Fluorescence Quantitation of Doxorubicin in Micro-volume Plasma: Applications to Pharmacokinetic Studies in Rats

    PubMed Central

    Daeihamed, Marjan; Haeri, Azadeh; Dadashzadeh, Simin

    2015-01-01

    A validated HPLC method was developed to determine the doxorubicin concentration in a small volume of rat plasma (60 µL) with convenient fluorescence detection. Sample preparation includes a simple one-step liquid-liquid extraction using a minimum amount of organic solvent, with extraction recovery more than 95%. The analysis was accomplished using PerfectSil C18 column maintained at 35 °C and a mobile phase consisted of acetonitrile and water (32:68, v/v; pH=2.6). The flow-rate was kept at 1 mL/min and the column effluent was monitored with a fluorescence detector at an excitation and emission wavelength of 470 and 555 nm, respectively. The detection limit was 5 ng/mL. No analytical interference was observed from endogenous components in the rat plasma. This method was feasibly applied to the pharmacokinetic study of 5 mg/Kg of doxorubicin after the intravenous administration to rats. PMID:26185503

  1. An ESIPT based fluorescent probe for highly selective and ratiometric detection of periodate.

    PubMed

    Huang, Chusen; Jia, Ti; Yu, Congjun; Zhang, Amin; Jia, Nengqin

    2015-01-15

    Periodate is widely used in organic and bioorganic chemistry, and also related to food and environmental safety. To best of our knowledge, there is no efficient tools reported for simultaneously quantifying periodate with high accuracy and discriminating periodate from other forms of iodine. We have synthesized, characterized and applied a first ratiometric fluorescent probe (PDS-2) for simultaneous monitoring of changes of periodate based on the excited-state intramolecular proton transfer mechanism. This PDS-2 based fluorescent technique may enable for a better understanding of periodate related biological and chemical processes. Also, it is an efficient tool for public health, food safety and environmental protection. PMID:25145984

  2. A highly sensitive and class-specific fluorescence polarisation assay for sulphonamides based on dihydropteroate synthase.

    PubMed

    Wang, Zhanhui; Liang, Xiao; Wen, Kai; Zhang, Suxia; Li, Chenglong; Shen, Jianzhong

    2015-08-15

    We describe a fluorescence polarisation assay based on the use of dihydropteroate synthase (DHPS) and a fluorescence probe for multi-sulphonamide detection. Dihydropteridine pyrophosphate (DHPPP) was synthesised and acts as the first substrate for DHPS. Under optimised conditions, the half-maximal inhibitory concentrations (IC50) of the assay were less than 100ngmL(-1) for at least 29 sulphonamides and the time needed for the detection was less than 20min. More importantly, the assay revealed quite uniform affinities for all of the individual sulphonamides tested, which has never before been achieved in an antibody-based assay. PMID:25775967

  3. Multicolor Fluorescence Writing Based on Host-Guest Interactions and Force-Induced Fluorescence-Color Memory.

    PubMed

    Matsunaga, Yuki; Yang, Jye-Shane

    2015-06-26

    A new strategy is reported for multicolor fluorescence writing on thin solid films with mechanical forces. This concept is illustrated by the use of a green-fluorescent pentiptycene derivative 1, which forms variably colored fluorescent exciplexes: a change from yellow to red was observed with anilines, and fluorescence quenching (a change to black) occurred in the presence of benzoquinone. Mechanical forces, such as grinding and shearing, induced a crystalline-to-amorphous phase transition in both the pristine and guest-adsorbed solids that led to a change in the fluorescence color (mechanofluorochromism) and a memory of the resulting color. Fluorescence drawings of five or more colors were created on glass or paper and could be readily erased by exposure to air and dichloromethane fumes. The structural and mechanistic aspects of the observations are also discussed. PMID:25982228

  4. DNA methyltransferase activity detection based on fluorescent silver nanocluster hairpin-shaped DNA probe with 5'-C-rich/G-rich-3' tails.

    PubMed

    Liu, Wenting; Lai, Han; Huang, Rong; Zhao, Chuntao; Wang, Yimo; Weng, Xiaocheng; Zhou, Xiang

    2015-06-15

    DNA methylation has received a large amount of attention due to its close relationship to a wide range of biological phenomena, such as gene activation, gene imprinting, and chromatin stability. Herein, we have designed a hairpin-shaped DNA probe with 5'-C-rich/G-rich-3' tails and developed a simple and reliable fluorescence turn-off assay for DNA adenine methylation (Dam) methyltransferase (MTase) detection combining site recognition and the fluorescence enhancement of DNA-templated silver nanoclusters (DNA-AgNCs) by guanine-rich DNA sequences. A designed hairpin probe with 5' CCCTTACCCC and 3' GGGTGGGGTGGGGTGGGG displays a bright red emission after reacting with AgNO3 and NaBH4. In the presence of Dam MTase, the methylation-sensitive restriction endonuclease Dpn I which has the same recognition site with the Dam MTase can split the probe, freeing the G-rich sequence from the C-rich sequence, thus quenching the fluorescence of DNA-AgNCs. Compared to traditional fluorescent-based methods, this strategy is simple and inexpensive. A linear response to concentrations of Dam MTase which range from 1 U/mL to 100 U/mL and a detection limit of 1 U/mL are obtained without any amplification steps. In addition, we also demonstrate the method can be used for evaluation and screening of inhibitors for Dam MTase. PMID:25682501

  5. SIMPLE PCB BASED S-PARAMETER EXTRACTION METHOD FOR RF AMPLIFIER CIRCUITS

    E-print Network

    Hwang, Sung Woo

    1 SIMPLE PCB BASED S-PARAMETER EXTRACTION METHOD FOR RF AMPLIFIER CIRCUITS S. C. Choi, J. E. Youm-parameters, de-embedding, printed circuit board (PCB), RF amplifier Abstract A new, simple S-parameter extraction method of RF transistor and amplifier is proposed and demonstrated. The method is based on one

  6. A simple formation-tracking controller of mobile robots based on a "spanning-tree" communication

    E-print Network

    Boyer, Edmond

    show that a simple condition on the reference angular velocity (persistency of excitation) suffices robots. In [7], an adaptive leader-follower based formation control without the need of leaders' velocityA simple formation-tracking controller of mobile robots based on a "spanning-tree" communication

  7. Frontispiece: Fluorescent Dendritic Organogels Based on 2-(2'-Hydroxyphenyl)benzoxazole: Emission Enhancement and Multiple Stimuli-Responsive Properties.

    PubMed

    Chen, Hui; Feng, Yu; Deng, Guo-Jun; Liu, Zhi-Xiong; He, Yan-Mei; Fan, Qing-Hua

    2015-07-27

    Smart Dendritic Fluorescent Organogels A new fluorescent dendritic organogel based on a poly(benzyl ether) dendron was developed that exhibited gelation-induced enhanced fluorescence emission properties. Most interestingly, these dendritic organogels exhibited multiple stimuli-responsive behaviors upon exposure to environmental stimuli including temperature, anions, metal cations, acids/bases, sonication, and shear stress, leading to reversible gel-sol phase transitions. For more details see the Full Paper by Q. H. Fan et al. on page?11018?ff. PMID:26184681

  8. On-chip integrated lensless fluorescence microscopy/spectroscopy module for cell-based sensors

    NASA Astrophysics Data System (ADS)

    Li, Wei; Knoll, Thorsten; Sossalla, Adam; Bueth, Heiko; Thielecke, Hagen

    2011-03-01

    The integration of a fluorescence microscopy/spectroscopy module in cell-based lab-on-a-chip systems is of high interest for applications in cell-based diagnostics and substance evaluation in situ. We present an on-chip integrated lensless fluorescence imaging module applying the principle of contact/proximate optical lithography. The pixel resolution is comparable with a 4 x objective microscope. The module can be used for morphology and fluorescence imaging of mammalian cells (15 - 20 ?m) as well as for testing the concentration of a fluorescent substance. The biological samples or solutions are sustained in disposable sterilized microfluidic chips with 1 ?m thick silicon nitride (Si3N4) membranes. These chips are assembled on the surface of a 5 megapixel colored CMOS image sensor array with 1.75 ?m pixel size, which is coated with an additional interference filter. Each culturing chip consists of a MEMS cavity chip and a PDMS microfluidic interface. The surface of the CMOS image sensor is smoothened using SU-8 photoresist spin-coating for a commercial grade interference filter (optical density >= 5) coating by Plasma-Ion Assisted Deposition thereafter. The function is demonstrated by primary imaging results of the non-/fluorescent mammalian cells/microspheres as well as by differentiating different concentrations of FITC solutions.

  9. Highly selective and sensitive nanoprobes for cyanide based on gold nanoclusters with red fluorescence emission.

    PubMed

    Zhang, Guomei; Qiao, Yunyun; Xu, Ting; Zhang, Caihong; Zhang, Yan; Shi, Lihong; Shuang, Shaomin; Dong, Chuan

    2015-08-01

    We report a novel and environmentally friendly fluorescent probe for detecting the cyanide ion (CN(-)) using l-amino acid oxidase (LAAOx)-protected Au nanoclusters (LAAOx@AuNCs) with red emission. The fluorescence-based sensing behaviour of LAAOx@AuNCs towards anions was investigated in buffered aqueous media. Among the anions studied, CN(-) was found to effectively quench the fluorescence emission of AuNCs based on CN(-) induced Au core decomposition. Excellent sensitivity and selectivity toward the detection of CN(-) in aqueous solution were observed. The CN(-) detection limit was determined to be approximately 180 nM, which is 15 times lower than the maximum level (2700 nM) of CN(-) in drinking water permitted by the World Health Organization (WHO). A linear relationship between the fluorescence intensity and CN(-) concentration was observed in two ranges of CN(-) concentration, including 3.2 × 10(-6) to 3.4 × 10(-5) mol L(-1) and 3.81 × 10(-5) to 1.04 × 10(-4) mol L(-1). The high sensitivity and selectivity to CN(-) among the 17 types of anions make the AuNCs good candidates for use in fluorescent nanoprobes of CN(-). PMID:26148527

  10. Development of Ultrasound-switchable Fluorescence Imaging Contrast Agents based on Thermosensitive Polymers and Nanoparticles

    PubMed Central

    Cheng, Bingbing; Wei, Ming-Yuan; Liu, Yuan; Pitta, Harish; Xie, Zhiwei; Hong, Yi; Nguyen, Kytai T.; Yuan, Baohong

    2015-01-01

    In this work we first introduced a recently developed high-resolution, deep-tissue imaging technique, ultrasound-switchable fluorescence (USF). The imaging principles based on two types of USF contrast agents were reviewed. To improve USF imaging techniques further, excellent USF contrast agents were developed based on high-performance thermoresponsive polymers and environment-sensitive fluorophores. Herein, such contrast agents were synthesized and characterized with five key parameters: (1) peak excitation and emission wavelengths (?ex and ?em), (2) the fluorescence intensity ratio between on and off states (IOn/IOff), (3) the fluorescence lifetime ratio between on and off states (?On/?Off), (4) the temperature threshold to switch on fluorophores (Tth), and (5) the temperature transition bandwidth (TBW). We mainly investigated fluorescence intensity and lifetime changes of four environment-sensitive dyes [7-(2-Aminoethylamino)-N,N-dimethyl-4-benzofurazansulfonamide (DBD-ED), St633, Sq660, and St700] as a function of temperature, while the dye was attached to poly(N-isopropylacrylamide) linear polymers or encapsulated in nanoparticles. Six fluorescence resonance energy transfer systems were invented in which both the donor (DBD-ED or ST425) and the acceptor (Sq660) were adopted. Our results indicate that three Förster resonance energy transfer systems, where both IOn/IOff and ?On/?Off are larger than 2.5, are promising for application in future surface tissue bioimaging by USF technique.

  11. Development of Fluorescence Sensing Material Based on CdSe/ZnS Quantum Dots and Molecularly Imprinted Polymer for the Detection of Carbaryl in Rice and Chinese Cabbage.

    PubMed

    Zhang, Can; Cui, Hanyu; Cai, Jianrong; Duan, Yuqing; Liu, Yuan

    2015-05-27

    A fluorescence sensing material based on quantum dots with excellent optical properties and molecularly imprinted polymer (QDs@MIP) with specific recognition has been developed. First the surface of CdSe/ZnS QDs was modified with ionic liquids (ILs) by electrostatic interaction. The fluorescence sensing material was constructed from anchoring the MIP layer on IL modified CdSe/ZnS QDs by copolymerization, which had been developed for the detection of carbaryl in rice and Chinese cabbage. The MIP fluorescence was more strongly quenched by carbaryl than the non-imprinted polymer (NIP) fluorescence, which indicated that the QDs@MIP could selectively recognize the corresponding carbaryl. Furthermore, the developed QDs@MIP method was validated by HPLC and ELISA respectively, and the results of these methods were well correlated (R(2) = 0.98). The fluorescence sensing material had obvious advantages, such as being easily prepared and having specific recognition and photostability. The developed method was simple and effective for the detection of carbaryl. And, it could also provide the technical support for the rapid detection in food safety fields. PMID:25946094

  12. Label-free and sensitive fluorescent detection of sequence-specific single-strand DNA based on S1 nuclease cleavage effects.

    PubMed

    Guan, Zheng; Liu, Jinchuan; Bai, Wenhui; Lv, Zhenzhen; Jiang, Xiaoling; Yang, Shuming; Chen, Ailiang; Lv, Guiyuan

    2014-01-01

    The ability to detect sequence-specific single-strand DNA (ssDNA) in complex, contaminant-ridden samples, using a fluorescent method directly without a DNA extraction and PCR step could simplify the detection of pathogens in the field and in the clinic. Here, we have demonstrated a simple label-free sensing strategy to detect ssDNA by employing its complementary ssDNA, S1 nuclease and nucleic acid fluorescent dyes. Upon clearing away redundant complementary ssDNA and possibly mismatched double strand DNA by using S1 nuclease, the fluorescent signal-to-noise ratio could be increased dramatically. It enabled the method to be adaptable to three different types of DNA fluorescent dyes and the ability to detect target ssDNA in complex, multicomponent samples, like tissue homogenate. The method can distinguish a two-base mismatch from avian influenza A (H1N1) virus. Also, it can detect the appearance of 50 pM target ssDNA in 0.5 µg · mL(-1) Lambda DNA, and 50 nM target ssDNA in 5 µg · mL(-1) Lambda DNA or in tissue homogenate. It is facile and cost-effective, and could be easily extended to detect other ssDNA with many common nucleic acid fluorescent dyes. PMID:25285445

  13. A turn-off fluorescent biosensor for the rapid and sensitive detection of uranyl ion based on molybdenum disulfide nanosheets and specific DNAzyme

    NASA Astrophysics Data System (ADS)

    Zhang, HongYan; Ruan, YaJuan; Lin, Ling; Lin, Minggui; Zeng, Xiaoxue; Xi, Zhiming; Fu, FengFu

    2015-07-01

    A novel fluorescent biosensor for detecting uranyl ion (UO22+) in aqueous environment has been developed based on the specific recognition of DNAzyme and the fluorescence quenching ability of molybdenum disulfide (MoS2) nanosheets. The DNAzyme contains a DNA enzyme strand and a 6-carboxylfluorescein (FAM)-labeled DNA substrate strand. We demonstrated that MoS2 nanosheets have low affinity to the substrate-enzyme complex DNAzyme. Whereas, in the presence of UO22+, UO22+ can specifically cleave DNAzyme to release FAM-labeled single-strand DNA and the released FAM-labeled single-strand DNA can be firmly adsorbed on the surface of MoS2 nanosheets, which resulted in an obvious decrease of fluorescence intensity. This provided a sensing platform for the rapid, simple and sensitive fluorescent detection of UO22+. By using the sensing platform, a sensitive and selective fluorescent method for the rapid detection of UO22+ has been developed. In comparison with previous biosensor, the proposed method has obvious analytical advantage such as relatively high sensitivity and good stability, short analytical time and low cost. It can be used to detect as low as 2.14 nM of UO22+ in aqueous environment with a recovery of 96-102% and a RSD < 5% (n = 6). The success of this study provides a promising alternative for the rapid and on-site detection of UO22+ in environmental monitoring.

  14. Development of fluorescence-based liposome immunoassay for detection of Cronobacter muytjensii in pure culture.

    PubMed

    Song, Xinjie; Shukla, Shruti; Oh, Sejong; Kim, Younghoan; Kim, Myunghee

    2015-02-01

    Cronobacter spp. are important foodborne pathogens that carry a very high risk of infection to neonates as well as immunocompromised individuals. In the present study, fluorescence-based liposome immunoassay was developed as a new sensitive and rapid diagnostic system for detection of Cronobacter muytjensii (C. muytjensii). Liposomes (size, 206 nm) used in this study were made from cholesterol, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)], and sulforhodamine B (SRB). The outer surface of liposome was conjugated with rabbit anti-C. muytjensii IgG in order to develop immunoliposome. The immunoliposome was incubated with C. muytjensii, which was coated on a 96-well plate. Immunoliposomes bound to C. muytjensii were lysed with 30 mM octyl ?-D-glucopyranoside, after which the SRB fluorescence signal was measured at an excitation wavelength of 550 nm and emission wavelength of 585 nm. The signal was directly proportional to the amount of bacterial cells in the test sample. The developed fluorescence-based liposome immunoassay was confirmed to be highly specific to C. muytjensii with a detection limit of 6.3 × 10(4) CFU ml(-1) in pure culture as well as sensitive, efficient, and rapid when compared to culture-based methods. Based on its rapid efficiency and low cost, this fluorescence-based liposome immunoassay may be used to develop diagnostic kits for C. muytjensii detection. PMID:25300633

  15. Label-free detection of kanamycin based on a G-quadruplex DNA aptamer-based fluorescent intercalator displacement assay.

    PubMed

    Xing, Yun-Peng; Liu, Chun; Zhou, Xiao-Hong; Shi, Han-Chang

    2015-01-01

    This work was the first to report that the kanamycin-binding DNA aptamer (5'-TGG GGG TTG AGG CTA AGC CGA-3') can form stable parallel G-quadruplex DNA (G4-DNA) structures by themselves and that this phenomenon can be verified by nondenaturing polyacrylamide gel electrophoresis and circular dichroism spectroscopy. Based on these findings, we developed a novel label-free strategy for kanamycin detection based on the G4-DNA aptamer-based fluorescent intercalator displacement assay with thiazole orange (TO) as the fluorescence probe. In the proposed strategy, TO became strongly fluorescent upon binding to kanamycin-binding G4-DNA. However, the addition of kanamycin caused the displacement of TO from the G4-DNA-TO conjugate, thereby resulting in decreased fluorescent signal, which was inversely related to the kanamycin concentration. The detection limit of the proposed assay decreased to 59?nM with a linear working range of 0.1??M to 20??M for kanamycin. The cross-reactivity against six other antibiotics was negligible compared with the response to kanamycin. A satisfactory recovery of kanamycin in milk samples ranged from 80.1% to 98.0%, confirming the potential of this bioassay in the measurement of kanamycin in various applications. Our results also served as a good reference for developing similar fluorescent G4-DNA-based bioassays in the future. PMID:25634469

  16. Heats of sublimation of nitramines based on simple parameters.

    PubMed

    Keshavarz, Mohammad Hossein; Yousefi, Mohammad Hassan

    2008-04-15

    In this work, a simple procedure is introduced to determine heats of sublimation of nitramines as an important class of explosives. Molecular weight and one structural parameter of nitramines would be needed in the new method. Calculated heats of sublimation for well-known explosives such as HMX [1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane], RDX [1,3,5-trinitro-1,3,5-triazacyclohexane] and TETRYL [1-(methylnitramino)-2,4,6-trinitrobenzene] as well as new nitramines CL-20 [2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane] and TNAZ [1,3,3-trinitroazatidine] show good agreement with experimental data. R-squared value or the coefficient of determination of new correlation is 0.945. The root-mean-square deviation (RMS) from experiment for the predicted heats of sublimation by new method is 10.10 kJ/mol. PMID:17765395

  17. Hyper-spectral modulation fluorescent imaging using double acousto-optical tunable filter based on TeO2-crystals

    NASA Astrophysics Data System (ADS)

    Zaytsev, Kirill I.; Perchik, Alexey V.; Chernomyrdin, Nikita V.; Kudrin, Konstantin G.; Reshetov, Igor V.; Yurchenko, Stanislav O.

    2015-01-01

    We have proposed a method for hyper-spectral fluorescent imaging based on acousto-optical filtering. The object of interest was pumped using ultraviolet radiation of mercury lamp equipped with monochromatic excitation filter with the window of transparency centered at 365 nm. Double TeO2-based acousto-optical filter, tunable in range from 430 to 780 nm and having 2 nm bandwidth of spectral transparency, was used in order to detect quasimonochromatic images of object fluorescence. Modulating of ultraviolet pump intensity was used in order to reduce an impact of non-fluorescent background on the sample fluorescent imaging. The technique for signal-to-noise ratio improvement, based on fluorescence intensity estimation via digital processing of modulated video sequence of fluorescent object, was introduced. We have implemented the proposed technique for the test sample studying and we have discussed its possible applications.

  18. A distance-dependent metal-enhanced fluorescence sensing platform based on molecular beacon design.

    PubMed

    Zhou, Zhenpeng; Huang, Hongduan; Chen, Yang; Liu, Feng; Huang, Cheng Zhi; Li, Na

    2014-02-15

    A new metal-enhanced fluorescence (MEF) based platform was developed on the basis of distance-dependent fluorescence quenching-enhancement effect, which combined the easiness of Ag-thiol chemistry with the MEF property of noble-metal structures as well as the molecular beacon design. For the given sized AgNPs, the fluorescence enhancement factor was found to increase with a d(6) dependency in agreement with fluorescence resonance energy transfer mechanism at shorter distance and decrease with a d(-3) dependency in agreement with plasmonic enhancement mechanism at longer distance between the fluorophore and the AgNP surface. As a proof of concept, the platform was demonstrated by a sensitive detection of mercuric ions, using thymine-containing molecular beacon to tune silver nanoparticle (AgNP)-enhanced fluorescence. Mercuric ions were detected via formation of a thymine-mercuric-thymine structure to open the hairpin, facilitating fluorescence recovery and AgNP enhancement to yield a limit of detection of 1 nM, which is well below the U.S. Environmental Protection Agency regulation of the Maximum Contaminant Level Goal (10nM) in drinking water. Since the AgNP functioned as not only a quencher to reduce the reagent blank signal but also an enhancement substrate to increase fluorescence of the open hairpin when target mercuric ions were present, the quenching-enhancement strategy can greatly improve the detection sensitivity and can in principle be a universal approach for various targets when combined with molecular beacon design. PMID:24080216

  19. Label-Free Detection of Sequence-Specific DNA Based on Fluorescent Silver Nanoclusters-Assisted Surface Plasmon-Enhanced Energy Transfer.

    PubMed

    Ma, Jin-Liang; Yin, Bin-Cheng; Le, Huynh-Nhu; Ye, Bang-Ce

    2015-06-17

    We have developed a label-free method for sequence-specific DNA detection based on surface plasmon enhanced energy transfer (SPEET) process between fluorescent DNA/AgNC string and gold nanoparticles (AuNPs). DNA/AgNC string, prepared by a single-stranded DNA template encoded two emitter-nucleation sequences at its termini and an oligo spacer in the middle, was rationally designed to produce bright fluorescence emission. The proposed method takes advantage of two strategies. The first one is the difference in binding properties of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) toward AuNPs. The second one is SPEET process between fluorescent DNA/AgNC string and AuNPs, in which fluorescent DNA/AgNC string can be spontaneously adsorbed onto the surface of AuNPs and correspondingly AuNPs serve as "nanoquencher" to quench the fluorescence of DNA/AgNC string. In the presence of target DNA, the sensing probe hybridized with target DNA to form duplex DNA, leading to a salt-induced AuNP aggregation and subsequently weakened SPEET process between fluorescent DNA/AgNC string and AuNPs. A red-to-blue color change of AuNPs and a concomitant fluorescence increase were clearly observed in the sensing system, which had a concentration dependent manner with specific DNA. The proposed method achieved a detection limit of ?2.5 nM, offering the following merits of simple design, convenient operation, and low experimental cost because of no chemical modification, organic dye, enzymatic reaction, or separation procedure involved. PMID:26024337

  20. Clinical performance of two fluorescence-based methods in detecting occlusal caries lesions in primary teeth.

    PubMed

    Matos, R; Novaes, T F; Braga, M M; Siqueira, W L; Duarte, D A; Mendes, F M

    2011-01-01

    This in vivo study aimed to evaluate the performance of 2 fluorescence-based methods in detecting occlusal caries lesions in primary teeth, compared with the performance of visual inspection and radiographic methods, and to propose a mathematic correction of the diagnostic parameters due to the imperfect reference standard method used in the study. Two examiners assessed the occlusal surfaces of 407 primary teeth (62 children) using visual inspection (ICDAS), radiographic, DIAGNOdent pen (pen type laser fluorescence; LFpen), and fluorescence camera (FC) methods. At the noncavitated threshold (NC) the reference standard method was the results of ICDAS, and at the dentine caries threshold (D3) teeth diagnosed with dentine caries by ICDAS or radiographic methods were subjected to operative treatment to confirm the presence of lesion. Reproducibility, sensitivity, specificity, accuracy, and the area under the ROC curve were calculated for the methods at both thresholds. At the NC threshold, LFpen had a slightly better performance compared to the FC and radiographic methods. However, at the D3 threshold, both fluorescence-based methods performed similarly. Visual inspection and radiographic methods presented higher specificities but lower sensitivities than fluorescence methods. After corrections, there was a significant decrease in some parameters. In conclusion, both fluorescence-based methods presented similar performance in detecting occlusal dentine caries lesions in primary teeth, but they usually gave more false-positive results than did the visual and radiographic methods. The correction proposed shows that the performance of the methods can be overestimated, and the correction should be validated and considered in further studies that use an imprecise reference standard method. PMID:21625126

  1. Fast-scanning two-photon fluorescence imaging based on a microelectromechanical systems two-

    E-print Network

    Schnitzer, Mark

    - dimensional scanning mirror Wibool Piyawattanametha, Robert P. J. Barretto, Tony H. Ko, Benjamin A. FlusbergFast-scanning two-photon fluorescence imaging based on a microelectromechanical systems two on microelectromechanical systems (MEMS) scanners. Single crystalline silicon scanning mirrors that are 0.75 mm 0.75 mm

  2. FLUORESCENCE AND FIBER-OPTICS BASED REAL-TIME THICKNESS SENSOR FOR DYNAMIC LIQUID FILMS

    E-print Network

    Narain, Amitabh

    1 FLUORESCENCE AND FIBER-OPTICS BASED REAL-TIME THICKNESS SENSOR FOR DYNAMIC LIQUID FILMS T. W. Ng phenomena and fiber-optic technology has been developed and reported here. Measurements from this sensor research and development fields. This paper focuses on a sensor capable of measuring interfacial wave

  3. Evaluation of Sustained BMP-2 Release Profiles Using a Novel Fluorescence-Based Retention Assay

    PubMed Central

    Jang, Jun-Hyeog

    2015-01-01

    The purpose of this study was to develop and characterize a novel fluorescence-based retention assay for the evaluation of the release profile of bone morphogenetic protein-2 (BMP-2) released from bone graft carrier. In this study, we evaluated the binding, release kinetics, and delivery efficacies of BMP-2 incorporated into hydroxyapatite (HA) bone grafts. The evaluation of the release profile of BMP-2 from HA bone grafts using a fluorescence-based retention assay revealed initial burst releases from the HA bone grafts followed by long sustained releases up to 14 weeks. The sustained biological activity of the released BMP-2 from HA bone grafts over the full 14-week period supports a long sustained mechanism via fluorescence-based retention assay. Thus, the results from this study show that BMP-2 could be incorporated into HA bone grafts for sustained release over a prolonged period of time with retention of bioactivity and our fluorescence-based retention assay, which is principally detecting the retention profile of BMP-2 in HA bone grafts, is more accurate than conventionally collecting the released BMP-2 for evaluation of BMP-2 release profiles. PMID:25901352

  4. Oriented Markov Random Field Based Dendritic Spine Segmentation for Fluorescence Microscopy Images

    E-print Network

    Miller, Eric

    1 Oriented Markov Random Field Based Dendritic Spine Segmentation for Fluorescence Microscopy of dendritic spines. Morphological analyses typically involve a significant component of computer-automatic approaches can largely reduce user efforts, by automatically detecting the dendritic spines with little human

  5. Clinical Performance of Two Fluorescence-Based Methods in Detecting Occlusal Caries Lesions in Primary Teeth

    Microsoft Academic Search

    R. Matos; T. F. Novaes; M. M. Braga; W. L. Siqueira; D. A. Duarte; F. M. Mendes

    2011-01-01

    This in vivo study aimed to evaluate the performance of 2 fluorescence-based methods in detecting occlusal caries lesions in primary teeth, compared with the performance of visual inspection and radiographic methods, and to propose a mathematic correction of the diagnostic parameters due to the imperfect reference standard method used in the study. Two examiners assessed the occlusal surfaces of 407

  6. Corrigendum: Drosophila Brainbow: a recombinase-based fluorescence labeling technique to subdivide neural expression patterns

    E-print Network

    Cai, Long

    tags via endogenous and antibody-based fluorescence analysis. (a­h) Maximum-intensity projections), and the V5 primary antibody is visualized with an Alexa Fluor 633 secondary antibody (blue). (The endogenous) and antibody to the V5 epitope visualized with Alexa Fluor 633 (blue); the coincidence of red and blue signals

  7. A ratiometric fluorescent probe for sensing HOCl based on a coumarin-rhodamine dyad.

    PubMed

    Zhang, Yan-Ru; Chen, Xin-Peng; Jing-Shao; Zhang, Jia-Yi; Yuan, Qiong; Miao, Jun-Ying; Zhao, Bao-Xiang

    2014-11-25

    We developed a ratiometric fluorescent probe for sensing HOCl based on coumarin and rhodamine acid that is directly used as a detection moiety. The probe shows high selectivity and sensitivity toward HOCl under best working conditions of myeloperoxidase by which HOCl can be generated from hydrogen peroxide and chloride. PMID:25283359

  8. New approach to breast tumor detection based on fluorescence x-ray analysis

    PubMed Central

    Hayashi, Yasuhiko; Okuyama, Fumio

    2010-01-01

    A new technical approach to breast-tumor detection is proposed. The technique is based on fluorescence x-ray analysis, and can identify a miniature malignant tumor within the breast. The primary beam intensity needed in fluorescence x-ray analysis is on a lower order of magnitude than that used in mammography. Thus, the newly-proposed technique would enable detection of a still tiny breast cancer while dramatically lowering the radiation dose. Field-emission x-ray sources might be a key for translating this concept into a medical technique. PMID:20930932

  9. A novel method for image denoising of fluorescence molecular imaging based on fuzzy C-Means clustering

    NASA Astrophysics Data System (ADS)

    An, Yu; Liu, Jie; Ye, Jinzuo; Mao, Yamin; Yang, Xin; Jiang, Shixin; Chi, Chongwei; Tian, Jie

    2015-03-01

    As an important molecular imaging modality, fluorescence molecular imaging (FMI) has the advantages of high sensitivity, low cost and ease of use. By labeling the regions of interest with fluorophore, FMI can noninvasively obtain the distribution of fluorophore in-vivo. However, due to the fact that the spectrum of fluorescence is in the section of the visible light range, there are mass of autofluorescence on the surface of the bio-tissues, which is a major disturbing factor in FMI. Meanwhile, the high-level of dark current for charge-coupled device (CCD) camera and other influencing factor can also produce a lot of background noise. In this paper, a novel method for image denoising of FMI based on fuzzy C-Means clustering (FCM) is proposed, because the fluorescent signal is the major component of the fluorescence images, and the intensity of autofluorescence and other background signals is relatively lower than the fluorescence signal. First, the fluorescence image is smoothed by sliding-neighborhood operations to initially eliminate the noise. Then, the wavelet transform (WLT) is performed on the fluorescence images to obtain the major component of the fluorescent signals. After that, the FCM method is adopt to separate the major component and background of the fluorescence images. Finally, the proposed method was validated using the original data obtained by in vivo implanted fluorophore experiment, and the results show that our proposed method can effectively obtain the fluorescence signal while eliminate the background noise, which could increase the quality of fluorescence images.

  10. Fluorescence suppression using wavelength modulated Raman spectroscopy in fiber-probe-based tissue analysis

    NASA Astrophysics Data System (ADS)

    Praveen, Bavishna B.; Ashok, Praveen C.; Mazilu, Michael; Riches, Andrew; Herrington, Simon; Dholakia, Kishan

    2012-07-01

    In the field of biomedical optics, Raman spectroscopy is a powerful tool for probing the chemical composition of biological samples. In particular, fiber Raman probes play a crucial role for in vivo and ex vivo tissue analysis. However, the high-fluorescence background typically contributed by the auto fluorescence from both a tissue sample and the fiber-probe interferes strongly with the relatively weak Raman signal. Here we demonstrate the implementation of wavelength-modulated Raman spectroscopy (WMRS) to suppress the fluorescence background while analyzing tissues using fiber Raman probes. We have observed a significant signal-to-noise ratio enhancement in the Raman bands of bone tissue, which have a relatively high fluorescence background. Implementation of WMRS in fiber-probe-based bone tissue study yielded usable Raman spectra in a relatively short acquisition time (~30 s), notably without any special sample preparation stage. Finally, we have validated its capability to suppress fluorescence on other tissue samples such as adipose tissue derived from four different species.

  11. A fluorescence-based method for rapid and direct determination of Polybrominated Diphenyl Ethers in Water

    SciTech Connect

    Shan, Huimei; Liu, Chongxuan; Wang, Zheming; Ma, Teng; Shang, Jianying; Pan, Duoqiang

    2015-01-01

    A new method was developed for rapid and direct measurement of aqueous polybrominated diphenyl ethers (PBDEs) using fluorescence spectroscopy. The fluorescence spectra of aqueous tri- to deca-BDE (BDE28, 47, 99, 153, 190 and 209) that are commonly found in environment were determined at variable emission and excitation wavelengths. The results revealed that the PBDEs have distinct fluorescence spectral profiles and peak positions that can be exploited to identify these species and determine their concentrations in aqueous solutions. The detection limits as determined in deionized water spiked with PBDEs are 1.71-5.82 ng/L for BDE28, BDE47, BDE190 and BDE209, and 45.55-69.95 ng/L for BDE99 and BDE153. The effects of environmental variables including pH, humic substance, and groundwater chemical composition on PBDEs measurements were also investigated. These environmental variables affected fluorescence intensity, but their effect can be corrected through linear additivity and separation of spectral signal contribution. Compared with conventional GC-based analytical methods, the fluorescence spectroscopy method is more efficient as it only uses a small amount of samples (4 ml), avoids lengthy complicated concentration and extraction steps, and has a low detection limit of a few ng/L.

  12. A fluorescence-based method for rapid and direct determination of polybrominated diphenyl ethers in water.

    PubMed

    Shan, Huimei; Liu, Chongxuan; Wang, Zheming; Ma, Teng; Shang, Jianying; Pan, Duoqiang

    2015-01-01

    A new method was developed for rapid and direct measurement of polybrominated diphenyl ethers (PBDEs) in aqueous samples using fluorescence spectroscopy. The fluorescence spectra of tri- to deca-BDE (BDE 28, 47, 99, 153, 190, and 209) commonly found in environment were measured at variable emission and excitation wavelengths. The results revealed that the PBDEs have distinct fluorescence spectral profiles and peak positions that can be exploited to identify these species and determine their concentrations in aqueous solutions. The detection limits as determined in deionized water spiked with PBDEs are 1.71-5.82?ng/L for BDE 28, BDE 47, BDE 190, and BDE 209 and 45.55-69.95?ng/L for BDE 99 and BDE 153. The effects of environmental variables including pH, humic substance, and groundwater chemical composition on PBDEs measurements were also investigated. These environmental variables affected fluorescence intensity, but their effect can be corrected through linear additivity and separation of spectral signal contribution. Compared with conventional GC-based analytical methods, the fluorescence spectroscopy method is more efficient as it only uses a small amount of samples (2-4?mL), avoids lengthy complicated concentration and extraction steps, and has a low detection limit of a few ng/L. PMID:25705548

  13. Fluorescent reversible regulation based on the interactions of topotecan hydrochloride, neutral red and quantum dots

    NASA Astrophysics Data System (ADS)

    Wang, Linlin; Shen, Yizhong; Liu, Shaopu; Yang, Jidong; Liang, Wanjun; Li, Dan; He, Youqiu

    2015-02-01

    The interactions of topotecan hydrochloride (THC), neutral red (NR) and thioglycolic acid (TGA) capped CdTe/CdS quantum dots (QDs) built a solid base for the controlling of the fluorescent reversible regulation of the system. This study was developed by means of ultraviolet-visible (UV-vis) absorption, fluorescence (FL), resonance Rayleigh scattering (RRS) spectroscopy and transmission electron microscopy (TEM). Corresponding experimental results revealed that the fluorescence of TGA-CdTe/CdS QDs could be effectively quenched by NR, while the RRS of the QDs enhanced gradually with the each increment of NR concentration. After the addition of THC, the strong covalent conjugation between NR and THC which was in carboxylate state enabled NR to be dissociated from the surface of TGA-CdTe/CdS QDs to form more stable complex with THC, thereby enhancing the fluorescence of the TGA-CdTe/CdS QDs-NR system. What is more, through analyzing the optical properties and experimental data of the reaction between TGA-CdTe/CdS QDs and NR, the possible reaction mechanism of the whole system was discussed. This combination of multiple spectroscopic techniques could contribute to the investigation for the fluorescent reversible regulation of QDs and a method could also be established to research the interactions between camptothecin drugs and dyes.

  14. A Fluorescent Thermometer Based on a Pyrene-Labeled Thermoresponsive Polymer

    PubMed Central

    Pietsch, Christian; Vollrath, Antje; Hoogenboom, Richard; Schubert, Ulrich S.

    2010-01-01

    Thermoresponsive polymers that undergo a solubility transition by variation of the temperature are important materials for the development of ‘smart’ materials. In this contribution we exploit the solubility phase transition of poly(methoxy diethylene glycol methacrylate), which is accompanied by a transition from hydrophilic to hydrophobic, for the development of a fluorescent thermometer. To translate the polymer phase transition into a fluorescent response, the polymer was functionalized with pyrene resulting in a change of the emission based on the microenvironment. This approach led to a soluble polymeric fluorescent thermometer with a temperature range from 11 °C to 21 °C. The polymer phase transition that occurs during sensing is studied in detail by dynamic light scattering. PMID:22163636

  15. Dopamine fluorescent sensors based on polypyrrole/graphene quantum dots core/shell hybrids.

    PubMed

    Zhou, Xi; Ma, Peipei; Wang, Anqi; Yu, Chenfei; Qian, Tao; Wu, Shishan; Shen, Jian

    2015-02-15

    A facilely prepared fluorescent sensor was developed for dopamine (DA) detection with high sensitivity and selectivity based on polypyrrole/graphene quantum dots (PPy/GQDs) core/shell hybrids. The composites exhibit strong fluorescence emission, which is dramatically enhanced as high as three times than pristine GQDs. The prepared sensor allows a highly sensitive determination of DA by fluorescent intensity decreasing with the addition of DA and presents a good linearity in range of 5-8000 nM with the detection limit of 10 pM (S/N = 3). Furthermore, the application of the proposed approach have been demonstrated in real samples and showed promise in diagnostic purposes. PMID:25278481

  16. A sensitive biosensor for the fluorescence detection of the acetylcholinesterase reaction system based on carbon dots.

    PubMed

    Ren, Xiangling; Wei, Jianfei; Ren, Jun; Qiang, Li; Tang, Fangqiong; Meng, Xianwei

    2015-01-01

    The carbon dots (C-dots) with high fluorescence quantum yield were prepared using hydrothermal method. C-dots have been adopted as probes for the fluorescence turn-off detection of H2O2 based on the special sensibility for the hydroxyl radical. And then the biosensors for the detection of substrate and enzymes activities were established in the acetylcholinesterase reaction system, which were related to the production of H2O2. Specifically, the proposed fluorescent biosensor was successfully applied to detect the concentration of choline (in the range from 0.025 to 50 ?M) and acetylcholine (in the range from 0.050 to 50 ?M), and the activity of choline oxidase (in the range from 1 to 75 U/L) and acetylcholinesterase (1 to 80 U/L). These results showed a sensitive, universal, nontoxic and eco-friendly detecting technique has been developed. PMID:25500325

  17. A fluorescence detection of D-penicillamine based on Cu2+-induced fluorescence quenching system of protein-stabilized gold nanoclusters

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Li, Bang Lin; Li, Nian Bing; Luo, Hong Qun

    2015-01-01

    In this contribution, a luminescent gold nanoclusters which were synthesized by bovine serum albumin as novel fluorescent probes were successfully utilized for the determination of D-penicillamine for the first time. Cupric ion was employed to quench the strong fluorescence of the gold nanoclusters, whereas the addition of D-penicillamine caused obvious restoration of fluorescence intensity of the Cu2+-gold nanoclusters system. Under optimum conditions, the increment in fluorescence intensity of Cu2+-gold nanoclusters system caused by D-penicillamine was linearly proportional to the concentration of D-penicillamine in the range of 2.0 × 10-5-2.39 × 10-4 M. The detection limit for D-penicillamine was 5.4 × 10-6 M. With the off-on fluorescence signal at 650 nm approaching the near-infrared region, the present sensor for D-penicillamine detection had high sensitivity and low spectral interference. Furthermore, the novel gold nanoclusters-based fluorescent sensor has been applied to the determination of D-penicillamine in real biological samples with satisfactory results.

  18. Nontemplated approach to tuning the spectral properties of cyanine-based fluorescent nanoGUMBOS.

    PubMed

    Das, Susmita; Bwambok, David; El-Zahab, Bilal; Monk, Joshua; de Rooy, Sergio L; Challa, Santhosh; Li, Min; Hung, Francisco R; Baker, Gary A; Warner, Isiah M

    2010-08-01

    Template-free controlled aggregation and spectral properties in fluorescent organic nanoparticles (FONs) is highly desirable for various applications. Herein, we report a nontemplated method for controlling the aggregation in near-infrared (NIR) cyanine-based nanoparticles derived from a group of uniform materials based on organic salts (GUMBOS). Cationic heptamethine cyanine dye 1,1',3,3,3',3'-hexamethylindotricarbocyanine (HMT) was coupled with five different anions, viz., [NTf(2)(-)], [BETI(-)], [TFPB(-)], [AOT(-)], and [TFP4B(-)], by an ion-exchange method to obtain the respective GUMBOS. The nanoGUMBOS obtained via a reprecipitation method were primarily amorphous and spherical (30-100 nm) as suggested by selected area electron diffraction (SAED) and transmission electron microscopy (TEM). The formation of tunable self-assemblies within the nanoGUMBOS was characterized using absorption and fluorescence spectroscopy in conjunction with molecular dynamics simulations. Counterion-controlled spectral properties observed in the nanoGUMBOS were attributed to variations in J/H ratios with different anions. Association with the [AOT(-)] anion afforded predominant J aggregation enabling the highest fluorescence intensity, whereas [TFP4B(-)] disabled the fluorescence due to predominant H aggregation in the nanoparticles. Analyses of the stacking angle of the cations based on molecular dynamic simulation results in [HMT][NTf(2)], [HMT][BETI], and [HMT][AOT] dispersed in water and a visual analysis of the representative simulation snapshots also imply that the type of aggregation was controlled through the counterion associated with the dye cation. PMID:20583774

  19. Simple membrane-based model of the Min oscillator

    NASA Astrophysics Data System (ADS)

    Petrášek, Zden?k; Schwille, Petra

    2015-04-01

    Min proteins in E. coli bacteria organize into a dynamic pattern oscillating between the two cell poles. This process identifies the middle of the cell and enables symmetric cell division. In an experimental model system consisting of a flat membrane with effectively infinite supply of proteins and energy source, the Min proteins assemble into travelling waves. Here we propose a simple one-dimensional model of the Min dynamics that, unlike the existing models, reproduces the sharp decrease of Min concentration when the majority of protein detaches from the membrane, and even the narrow MinE maximum immediately preceding the detachment. The proposed model thus provides a possible mechanism for the formation of the MinE ring known from cells. The model is restricted to one dimension, with protein interactions described by chemical kinetics allowing at most bimolecular reactions, and explicitly considering only three, membrane-bound, species. The bulk solution above the membrane is approximated as being well-mixed, with constant concentrations of all species. Unlike other models, our proposal does not require autocatalytic binding of MinD to the membrane. Instead, it is assumed that two MinE molecules are necessary to induce the dissociation of the MinD dimer and its subsequent detachment from the membrane. We investigate which reaction schemes lead to unstable homogeneous steady states and limit cycle oscillations, and how diffusion affects their stability. The suggested model qualitatively describes the shape of the Min waves observed on flat membranes, and agrees with the experimental dependence of the wave period on the MinE concentration. These results highlight the importance of MinE presence on the membrane without being bound to MinD, and of the reactions of Min proteins on the membrane.

  20. A quadruplex-based, label-free, and real-time fluorescence assay for RNase H activity and inhibition.

    PubMed

    Hu, Dan; Pu, Fang; Huang, Zhenzhen; Ren, Jinsong; Qu, Xiaogang

    2010-02-22

    We demonstrate a unique quadruplex-based fluorescence assay for sensitive, facile, real-time, and label-free detection of RNase H activity and inhibition by using a G-quadruplex formation strategy. In our approach, a RNA-DNA substrate was prepared, with the DNA strand designed as a quadruplex-forming oligomer. Upon cleavage of the RNA strand by RNase H, the released G-rich DNA strand folds into a quadruplex in the presence of monovalent ions and interacts with a specific G-quadruplex binder, N-methyl mesoporphyrin IX (NMM); this gives a dramatic increase in fluorescence and serves as a reporter of the reaction. This novel assay is simple in design, fast in operation, and is more convenient and promising than other methods. It takes less than 30 min to finish and the detection limit is much better or at least comparable to previous reports. No sophisticated experimental techniques or chemical modification for either RNA or DNA are required. The assay can be accomplished by using a common spectrophotometer and obviates possible interference with the kinetic behavior of the catalysts. Our approach offers an ideal system for high-throughput screening of enzyme inhibitors and demonstrates that the structure of the G-quadruplex can be used as a functional tool in specific fields in the future. PMID:20077530

  1. A simple raster-based model for flood inundation simulation

    Microsoft Academic Search

    P. D Bates; A. P. J De Roo

    2000-01-01

    In this paper the development of a new model for simulating flood inundation is outlined. The model is designed to operate with high-resolution raster Digital Elevation Models, which are becoming increasingly available for many lowland floodplain rivers and is based on what we hypothesise to be the simplest possible process representation capable of simulating dynamic flood inundation. This consists of

  2. Understanding Wax Printing: A Simple Micropatterning Process for Paper-Based

    E-print Network

    Prentiss, Mara

    Understanding Wax Printing: A Simple Micropatterning Process for Paper-Based Microfluidics Emanuel a detailed study on wax printing, a simple and inexpensive method for fabricating microfluidic devices in paper using a commercially avail- able printer and hot plate. The printer prints patterns of solid wax

  3. Sensing of trace amounts of cadmium in drinking water using a single fluorescence-based optosensor

    Microsoft Academic Search

    Juan F. García-Reyes; Pilar Ortega-Barrales; Antonio Molina-Díaz

    2006-01-01

    In this work, a single solid surface fluorescence based flow-through optosensor has been developed for the determination of trace amounts of cadmium in drinking water samples. The developed methodology is based on the transient immobilization of the target species on an appropriate active solid sensing zone (Sephadex QAE-A25).The target species was the fluorogenic chelate, formed as a result of the

  4. Dual-emission fluorescent sensor based on AIE organic nanoparticles and Au nanoclusters for the detection of mercury and melamine

    NASA Astrophysics Data System (ADS)

    Niu, Caixia; Liu, Qiuling; Shang, Zhehai; Zhao, Liu; Ouyang, Jin

    2015-04-01

    A novel dual-emission ratiometric fluorescence probe is designed and developed by linking two parts, positively charged aggregation-induced emission (AIE) organic fluorescence nanoparticles (OFNs) as the reference and negatively charged Au nanoclusters (Au NCs) as the response, by electrostatic attraction for the first time. This probe can be used for not only visual but quantitative determination of Hg2+ as well as melamine, because red fluorescence of Au NCs can be quenched by mercury ions and recovered by melamine, due to the strong affinity metallophilic Hg2+-Au interaction and stronger affinity Hg2+-N. During this process, the green fluorescence of AIE-OFNs remains constant owing to the protection of ?-polylysine (?-Ply). In addition, the prepared dual-emission ratiometric fluorescence probe has good biocompatibility, indicating the potential of the probe in applications of biological imaging and detection. The results revealed that this dual-emission ratiometric fluorescence probe broadens the application of AIE-based organic fluorescent nanoparticles, and presents a new method to prepare more sensitive, biocompatible, and visual ratiometric fluorescent probes.A novel dual-emission ratiometric fluorescence probe is designed and developed by linking two parts, positively charged aggregation-induced emission (AIE) organic fluorescence nanoparticles (OFNs) as the reference and negatively charged Au nanoclusters (Au NCs) as the response, by electrostatic attraction for the first time. This probe can be used for not only visual but quantitative determination of Hg2+ as well as melamine, because red fluorescence of Au NCs can be quenched by mercury ions and recovered by melamine, due to the strong affinity metallophilic Hg2+-Au interaction and stronger affinity Hg2+-N. During this process, the green fluorescence of AIE-OFNs remains constant owing to the protection of ?-polylysine (?-Ply). In addition, the prepared dual-emission ratiometric fluorescence probe has good biocompatibility, indicating the potential of the probe in applications of biological imaging and detection. The results revealed that this dual-emission ratiometric fluorescence probe broadens the application of AIE-based organic fluorescent nanoparticles, and presents a new method to prepare more sensitive, biocompatible, and visual ratiometric fluorescent probes. Electronic supplementary information (ESI) available: Synthesis routes and 1H NMR spectrum of 9,10-bis(3-formylstyryl)anthracene; FT-IR spectra, zeta potential, fluorescence spectra and corresponding FL intensity of Ply-BFSA OFNs; zeta potential, absorption, excitation, emission spectra, and fluorescent pictures of the aqueous solution of Au NCs; MTT assay of HeLa cells treated with different concentrations of Au NCs and Ply-BFSA OFNs for 24 h. See DOI: 10.1039/c5nr00554j

  5. Blood interference in fiber-optical based fluorescence guided resection of glioma using 5-aminolevulinic acid

    NASA Astrophysics Data System (ADS)

    Haj-Hosseini, Neda; Lowndes, Shannely; Salerud, Göran; Wårdell, Karin

    2011-03-01

    Fluorescence guidance in brain tumor resection is performed intra-operatively where bleeding is included. When using fiber-optical probes, the transmission of light to and from the tissue is totally or partially blocked if a small amount of blood appears in front of the probe. Sometimes even after rinsing with saline, the remnant blood cells on the optical probe head, disturb the measurements. In such a case, the corresponding spectrum cannot be reliably quantified and is therefore discarded. The optimal case would be to calculate and take out the blood effect systematically from the collected signals. However, the first step is to study the pattern of blood interference in the fluorescence spectrum. In this study, a fiber-optical based fluorescence spectroscopy system with a laser excitation light of 405 nm (1.4 J/cm2) was used during fluorescence guided brain tumor resection using 5-aminolevulinic acid (5-ALA). The blood interference pattern in the fluorescence spectrum collected from the brain was studied in two patients. The operation situation was modeled in the laboratory by placing blood drops from the finger tip on the skin of forearm and the data was compared to the brain in vivo measurements. Additionally, a theoretical model was developed to simulate the blood interference pattern on the skin autofluorescence. The blood affects the collected fluorescence intensity and leaves traces of oxy and deoxy-hemoglobin absorption peaks. According to the developed theoretical model, the autofluorescence signal is considered to be totally blocked by an approximately 500 ?m thick blood layer.

  6. Nicking enzyme-assisted biosensor for Salmonella enteritidis detection based on fluorescence resonance energy transfer.

    PubMed

    Song, Yang; Li, Wenkai; Duan, Yingfen; Li, Zhongjie; Deng, Le

    2014-05-15

    Salmonella enteritidis (S. enteritidis) outbreaks continue to occur, and have increased public awareness of this pathogen. Nicking endonuclease Nb.BbvC I is widely used for the detection of biomolecules and displays activity for specific double-stranded DNA (dsDNA). In this study, we developed a biosensor to detect S. enteritidis based on fluorescence resonance energy transfer (FRET) using nicking enzyme and carbon nanoparticles (CNPs). Because of the quenching effect of black hole quencher 1 (BHQ 1), the CNPs do not fluoresce in the reaction system. When the target bacteria are added, the nicking enzyme recognizes and cleaves the dsDNA fabricated by the interaction between probe and target. As a result, the CNPs dissociate from BHQ 1 and emit strong fluorescence. Using the nicking enzyme, the fluorescence signals of the biosensor are greatly amplified. The biosensor exhibited a linear relationship with the concentration of S. enteritidis ranging from 10(2) to 3 × 10(3)CFU/mL in water and from 1.5 × 10(2) to 3 × 10(3)CFU/mL in milk. The present results indicate that our FRET-based detection system can be widely employed for the effective detection of pathogens. PMID:24434495

  7. Fluorescence imaging of siRNA delivery by peptide nucleic acid-based probe.

    PubMed

    Sato, Takaya; Sato, Yusuke; Iwai, Kenta; Kuge, Shusuke; Teramae, Norio; Nishizawa, Seiichi

    2015-01-01

    We report on the use of a peptide nucleic acid (PNA)-based fluorescent probe for the analysis of siRNA delivery to living cells. The probe, Py-AA-TO, possesses thiazole orange (TO) and pyrene moieties in the C- and N-termini of PNA, and can function as a light-up probe capable of selective binding to 3'-overhanging nucleotides of target siRNAs. The affinity-labeling of the siRNAs with Py-AA-TO facilitates fluorescence imaging of cellular uptake of polymer-based carriers encapsulating the siRNAs (polyplexes) through endocytosis and subsequent sequestration into lysosome. In addition, flow cytometric measurements reveal that the monitoring of Py-AA-TO fluorescence inside the cells is successfully applicable to the analysis of the polyplex disassembly. These promising functions of Py-AA-TO are presented and discussed as a basis for the design of molecular probes for fluorescent imaging and quantitative analysis of the siRNA delivery process. PMID:25864675

  8. Compact flashlamp-based fluorescence imager for use under ambient-light conditions.

    PubMed

    Lanni, Frederick; Pane, David A; Weinstein, Shmuel J; Waggoner, Alan S

    2007-03-01

    A low-power, lightweight, multiwavelength fluorescence imager based on the use of a compact xenon flashlamp, bandpass filters, gated charge-coupled device camera, and digital image processing was developed for use on an autonomous rover vehicle. The imager discriminates against ambient light by use of microsecond excitation pulses along with synchronized camera operation to limit the time period in which ambient-light photocounts are accumulated, and digital image subtraction to remove background counts. In a 10 cm square field of view, weak fluorescence, equivalent to 0.05 pmol fluorescein/mm(2), can be quantified against a white-light background equivalent to shaded sunlight. For application in autonomous search for organisms in extreme environments such as in situ desert rock or soil, the instrument was equipped with a set of fluorescence excitation filters (380, 450, 545, and 600 nm) and emission filters (460, 510, 620, and 740 nm) suitable for detection of chlorophyll, applied stains for protein, DNA, lipid and carbohydrate, and autofluorescence. True-color images were obtained through red-green-blue imaging filters (630, 535, and 470 nm) used with white-light flashes. Automated focusing on ground features was based on the R-band image and was carried out prior to fluorescence image acquisition. PMID:17411186

  9. Fluorescence-based sensing of glucose using engineered glucose/galactose-binding protein: A comparison of fluorescence resonance energy transfer and environmentally sensitive dye labelling strategies

    SciTech Connect

    Khan, Faaizah; Gnudi, Luigi [Metabolic Unit, King's College London School of Medicine, Guy's Hospital, London SE1 9RT (United Kingdom); Pickup, John C. [Metabolic Unit, King's College London School of Medicine, Guy's Hospital, London SE1 9RT (United Kingdom)], E-mail: john.pickup@kcl.ac.uk

    2008-01-04

    Fluorescence-based glucose sensors using glucose-binding protein (GBP) as the receptor have employed fluorescence resonance energy transfer (FRET) and environmentally sensitive dyes, but with widely varying sensitivity. We therefore compared signal changes in (a) a FRET system constructed by transglutaminase-mediated N-terminal attachment of Alexa Fluor 488/555 as donor and QSY 7 as acceptor at Cys 152 or 182 mutations with (b) GBP labelled with the environmentally sensitive dye badan at C152 or 182. Both FRET systems had a small maximal fluorescence change at saturating glucose (7% and 16%), badan attached at C152 was associated with a 300% maximal fluorescence increase with glucose, though with badan at C182 there was no change. We conclude that glucose sensing based on GBP and FRET does not produce a larger enough signal change for clinical use; both the nature of the environmentally sensitive dye and its site of conjugation seem important for maximum signal change; badan-GBP152C has a large glucose-induced fluorescence change, suitable for development as a glucose sensor.

  10. A simple data base for identification of risk profiles

    SciTech Connect

    Munganahalli, D.

    1996-12-31

    Sedco Forex is a drilling contractor that operates approximately 80 rigs on land and offshore worldwide. The HSE management system developed by Sedco Forex is an effort to prevent accidents and minimize losses. An integral part of the HSE management system is establishing risk profiles and thereby minimizing risk and reducing loss exposures. Risk profiles are established based on accident reports, potential accident reports and other risk identification reports (RIR) like the Du Pont STOP system. A rig could fill in as many as 30 accident reports, 30 potential accident reports and 500 STOP cards each year. Statistics are important for an HSE management system, since they are indicators of success or failure of HSE systems. It is however difficult to establish risk profiles based on statistical information, unless tools are available at the rig site to aid with the analysis. Risk profiles are then used to identify important areas in the operation that may require specific attention to minimize the loss exposure. Programs to address the loss exposure can then be identified and implemented with either a local or corporate approach. In January 1995, Sedco Forex implemented a uniform HSE Database on all the rigs worldwide. In one year companywide, the HSE database would contain information on approximately 500 accident and potential accident reports, and 10,000 STOP cards. This paper demonstrates the salient features of the database and describes how it has helped in establishing key risk profiles. It also shows a recent example of how risk profiles have been established at the corporate level and used to identify the key contributing factors to hands and finger injuries. Based on this information, a campaign was launched to minimize the frequency of occurrence and associated loss attributed to hands and fingers accidents.

  11. Fluorescent cell-based sensing approaches for toxicity testing

    Microsoft Academic Search

    Michael Fritzsche; Carl-Fredrik Mandenius

    2010-01-01

    Fluorimetric cell-based sensing methods have attracted increasing interest in toxicity testing of pharmaceuticals, pathogens,\\u000a environmental pollutants, and other chemicals. The objective of this review is to summarise the variety of approaches reported\\u000a up to now and to present recent developments in this area. The different approaches are described in relation to their underlying\\u000a mechanism and, especially, to the role of

  12. Development of a competitive fluorescence-based synaptosome binding assay for brevetoxins

    PubMed Central

    McCall, Jennifer R.; Jacocks, Henry M.; Baden, Daniel G.; Bourdelais, Andrea J.

    2012-01-01

    Brevetoxins are a family of ladder-frame polyether toxins produced during blooms of the marine dinoflagellate Karenia brevis. Inhalation of brevetoxins aerosolized by wind and wave action can lead to asthma-like symptoms in beach goers. Consumption of either shellfish or finfish exposed to K. brevis blooms can lead to the development of neurotoxic shellfish poisoning. The toxic effects of brevetoxins are due to activation of voltage-sensitive sodium channels (VSSCs) in cell membranes. Binding of brevetoxin analogs and competitors to site 5 on these channels has historically been measured using a radioligand competition assay that is fraught with difficulty, including slow analysis time, production of radioactive waste, and cumbersome and expensive methods associated with the generation of radioactive labeled ligands. In this study, we describe the development of a novel fluorescent synaptosome binding assay for the brevetoxin receptor. BODIPY®-conjugated to PbTx-2 was used as the labeled ligand. The BODIPY®-PbTx-2 conjugate was found to displace [3H]-PbTx-3 from its binding site on VSSCs on rat brain synaptosomes with an equilibrium inhibition constant of 0.11 nM. We have shown that brevetoxin A and B analogs are all able to compete for binding with the fluorescent ligand. Most importantly, this assay was validated against the current site 5 receptor binding assay standard, the radioligand receptor assay for the brevetoxin receptor using [3H]-PbTx-3 as the labeled ligand. The fluorescence based assay yielded equilibrium inhibition constants comparable to the radioligand assay for all brevetoxin analogs. The fluorescence based assay was quicker, far less expensive, and did not generate radioactive waste or need radioactive facilities. As such, this fluorescence-based assay can be used to replace the current radioligand assay for site 5 on voltage-sensitive sodium channels and will be a vital tool for future experiments examining the binding affinity of various ligands for site 5 on sodium channels. PMID:22984362

  13. Conditionally fluorescent molecular probes for detecting single base changes in double-stranded DNA

    PubMed Central

    Chen, Sherry Xi; Zhang, David Yu; Seelig, Georg

    2013-01-01

    Small variations in nucleic acid sequences can have far-reaching phenotypic consequences. Reliably distinguishing closely related sequences is therefore important for research and clinical applications. Here, we demonstrate that conditionally fluorescent DNA probes are capable of distinguishing variations of a single base in a stretch of target DNA. These probes use a novel programmable mechanism in which each single nucleotide polymorphism generates two thermodynamically destabilizing mismatch bubbles rather than the single mismatch formed during typical hybridization-based assays. Up to 12,000-fold excess of a target containing a single nucleotide polymorphism is required to generate the same fluorescence as one equivalent of the intended target, and detection works reliably over a wide range of conditions. Using these probes we detected point mutations in a 198 base pair subsequence of the E. Coli rpoB gene. Our probes are constructed from multiple oligonucleotide fragments, circumventing synthesis limitations and enabling long continuous DNA sequences to be probed. PMID:23965681

  14. Conditionally fluorescent molecular probes for detecting single base changes in double-stranded DNA

    NASA Astrophysics Data System (ADS)

    Chen, Sherry Xi; Zhang, David Yu; Seelig, Georg

    2013-09-01

    Small variations in nucleic acid sequences can have far-reaching phenotypic consequences. Reliably distinguishing closely related sequences is therefore important for research and clinical applications. Here, we demonstrate that conditionally fluorescent DNA probes are capable of distinguishing variations of a single base in a stretch of target DNA. These probes use a novel programmable mechanism in which each single nucleotide polymorphism generates two thermodynamically destabilizing mismatch bubbles rather than the single mismatch formed during typical hybridization-based assays. Up to a 12,000-fold excess of a target that contains a single nucleotide polymorphism is required to generate the same fluorescence as one equivalent of the intended target, and detection works reliably over a wide range of conditions. Using these probes we detected point mutations in a 198 base-pair subsequence of the Escherichia coli rpoB gene. That our probes are constructed from multiple oligonucleotides circumvents synthesis limitations and enables long continuous DNA sequences to be probed.

  15. Detection of saccharides with a fluorescent sensing device based on a gold film modified with 4-mercaptophenylboronic acid monolayer

    NASA Astrophysics Data System (ADS)

    Chen, Shu-Jen; Chang, Jui-Feng; Cheng, Nai-Jen; Yih, Jeng-Nan; Chiu, Kuo-Chi

    2013-09-01

    An extremely sensitive fluorescent sensor based on a phenylboronic acid monolayer was developed for detecting saccharide molecules. The fluorescent sensor was prepared by assembling a monolayer of 4-mercaptophenylboronic acid (4-MPBA) onto a gold-coated compact disk. The change in the fluorescence of the 4-MPBA monolayer was extremely obvious in basic methanolic buffer containing monosaccharides down to the picomolar level. The fluorescence spectra demonstrated that the 4-MPBA monolayer was sensitive to monosaccharides and disaccharides, and the affinity of the monolayer toward saccharides was in the order of glucose < fructose < mannose < galactose < maltose > lactose > sucrose. Additionally, the fluorescence intensity of 4-MPBA monolayer was restorable after cleaning with weak acid, indicating that the reported fluorescent sensor with the detection limit of glucose down to the picomolar level is reusable for sensing saccharides.

  16. Hydrogen Sulfide Deactivates Common Nitrobenzofurazan-Based Fluorescent Thiol Labeling Reagents

    PubMed Central

    2015-01-01

    Sulfhydryl-containing compounds, including thiols and hydrogen sulfide (H2S), play important but differential roles in biological structure and function. One major challenge in separating the biological roles of thiols and H2S is developing tools to effectively separate the reactivity of these sulfhydryl-containing compounds. To address this challenge, we report the differential responses of common electrophilic fluorescent thiol labeling reagents, including nitrobenzofurazan-based scaffolds, maleimides, alkylating agents, and electrophilic aldehydes, toward cysteine and H2S. Although H2S reacted with all of the investigated scaffolds, the photophysical response to each scaffold was significantly different. Maleimide-based, alkylating, and aldehydic thiol labeling reagents provided a diminished fluorescence response when treated with H2S. By contrast, nitrobenzofurazan-based labeling reagents were deactivated by H2S addition. Furthermore, the addition of H2S to thiol-activated nitrobenzofurazan-based reagents reduced the fluorescence signal, thus establishing the incompatibility of nitrobenzofurazan-based thiol labeling reagents in the presence of H2S. Taken together, these studies highlight the differential reactivity of thiols and H2S toward common thiol-labeling reagents and suggest that sufficient care must be taken when labeling or measuring thiols in cellular environments that produce H2S due to the potential for both false-positive and eroded responses. PMID:24852143

  17. Scenario based outdoor simulation in pre-hospital trauma care using a simple mannequin model

    Microsoft Academic Search

    Per P Bredmose; Karel Habig; Gareth Davies; Gareth Grier; David J Lockey

    2010-01-01

    INTRODUCTION: We describe a system of scenario-based training using simple mannequins under realistic circumstances for the training of pre-hospital care providers. METHODS: A simple intubatable mannequin or student volunteers are used together with a training version of the equipment used on a routine basis by the pre-hospital care team (doctor + paramedic). Training is conducted outdoors at the base location

  18. A "turn-on" silver nanocluster based fluorescent sensor for folate receptor detection and cancer cell imaging under visual analysis.

    PubMed

    Jiang, Hong; Xu, Gang; Sun, Yimin; Zheng, Weiwei; Zhu, Xiangxiang; Wang, Baojuan; Zhang, Xiaojun; Wang, Guangfeng

    2015-07-01

    A novel terminal protection based label-free and "turn-on" fluorescent sensor for detection of folate receptors (FRs) and HeLa cells is developed by fluorescence resonance energy transfer (FRET) between single-walled carbon nanotubes (SWCNTs) and silver nanoclusters (AgNCs). Multilevel visual analysis (m(2)VA) was firstly proposed and applied in optimizing the experimental parameters. PMID:26108636

  19. Ultrafast method for the analysis of fluorescence lifetime imaging microscopy data based on the Laguerre expansion technique

    Microsoft Academic Search

    Javier A. Jo; Qiyin Fang; Laura Marcu

    2005-01-01

    We report a new deconvolution method for fluorescence lifetime imaging microscopy (FLIM) based on the Laguerre expansion technique. The performance of this method was tested on synthetic and real FLIM images. The following interesting properties of this technique were demonstrated. 1) The fluorescence intensity decay can be estimated simultaneously for all pixels, without a priori assumption of the decay functional

  20. Synchronous fluorescence measurement of enrofloxacin in the pharmaceutical formulation and its residue in milks based on the yttrium (III)-perturbed luminescence.

    PubMed

    Tong, Changlun; Zhuo, Xiajun; Liu, Weiping; Wu, Jianmin

    2010-10-15

    A simple, rapid and sensitive synchronous fluorescence method is put forward for the determination of enrofloxacin (ENRO) in the pharmaceutical formulation and its residue in milk based on the yttrium (III)-perturbed luminescence. When Y(3+) is added into the ENRO solution, the fluorescence of ENRO is significantly enhanced. The synchronous fluorescence technology is employed in the method to determine trace amount of ENRO residue in milks. The synchronous fluorescence intensity of the system is measured in a 1-cm quartz cell with excitation wavelength of 328 nm, ??=80 nm. A good linear relationship between the fluorescence intensity and the ENRO concentration is obtained in the range of 1.0 × 10(-9) to 2.0 × 10(-6)mol L(-1) (r(2)=0.9992). The limit of detection (LOD) of this method attains as low as 3.0 × 10(-10) mol L(-1) (S/N=3). The selectivity of this method is also very good. Common metal ions, rare-earth ions and some pharmaceuticals, which are usually used together with ENRO, do not interfere with the determination of ENRO under the actual conditions. The proposed method can be applied to determine ENRO residue in milks, and limit of quantification (LOQ) determined in the spiked milk is estimated to be 2.8 × 10(-8) mol L(-1) (10 ?g L(-1)). Moreover, this method can be used as a rapid screening for judging whether the ENRO residues in milks exceed Minimal Risk Levels (MRLs) or not. In addition, the mechanism of the fluorescence enhancement is also discussed in detail. PMID:20875588

  1. Development of bio-photonic sensor based on laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Kim, Chan Kyu

    Laser-induced fluorescence (LIF) has been shown to be potentially useful for identifying microorganisms in real time. It is a selective and sensitive technique because the excitation is performed at one wavelength while the emission is monitored at longer wavelengths so that background from the excitation source can be eliminated. This specialized optical property of LIF can be applied to development of an optical sensor capable of quickly, non-invasively, and quantitatively probing complex biochemical transformations in microorganisms. Various bio-photonic optical fiber sensors based on laser-induced fluorescence (LIF) spectroscopy were developed as diagnostic tools for microorganisms. In the first phase, the enhancement of the sensitivity and selectivity of the optical sensor system focused on diagnosis of human breast cancer cell lines and Azotobacter vinelandii (an aerobic soil-dwelling organism). Auto-fluorescence spectra from human breast cancer cell lines and Azotobacter vinelandii corresponding to different growth environments were investigated. Then, the study has expanded to include the use of gold nanoparticles for specific DNA detection. The use of gold nanoparticles opens a door into construction of a compact, highly specific, inexpensive and user-friendly optical fiber senor for specific DNA detection. An optical fiber laser-induced fluorescence (LIF) sensor based has been developed to detect single-strand (ss) DNA hybridization at the femtomolar level. Effects of various experimental parameters and configuration were investigated in order to optimize sensor performance and miniaturize sensor size. Key words. Laser induced fluorescence, human breast cancer cell lines, Azotobacter vinelandii, DNA, gold nanoparticles.

  2. A simple, rapid and high-throughput fluorescence polarization immunoassay for simultaneous detection of organophosphorus pesticides in vegetable and environmental water samples.

    PubMed

    Xu, Zhen-Lin; Wang, Qiang; Lei, Hong-Tao; Eremin, Sergei A; Shen, Yu-Dong; Wang, Hong; Beier, Ross C; Yang, Jin-Yi; Maksimova, Ksenia A; Sun, Yuan-Ming

    2011-12-01

    A simple, rapid and high-throughput fluorescent polarization immunoassay (FPIA) for simultaneous determination of organophosphorus pesticides (OPs) using a broad-specificity monoclonal antibody was developed. The effects of tracer structure, tracer concentration, antibody dilution, methanol content and matrix effect on FPIA performance were studied. The FPIA can detect 5 OPs simultaneously with a limit of detection below 10 ng mL(-1). The time required for the equilibrium of antibody-antigen interaction was less than 10 min. The recovery from spiked vegetable and environmental samples ranged from 71.3% to 126.8%, with the coefficient of variations ranging from 3.5% to 14.5%. The developed FPIA was applied to samples, followed by confirmation with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis. The developed FPIA demonstrated good accuracy and reproducibility, and is suitable for rapid and high-throughput screening for OP contamination with high-efficiency and low cost. PMID:22093354

  3. Label-free nucleic acids detection based on DNA templated silver nanoclusters fluorescent probe.

    PubMed

    Zhao, Haiyan; Wang, Lei; Zhu, Jing; Wei, Haiping; Jiang, Wei

    2015-06-01

    Based on DNA templated Ag NCs (DNA/Ag NCs) fluorescent probe, a label-free fluorescent method was developed for the detection of clinical significant DNA fragments from human immunodeficiency virus type 1 (HIV-1) DNA. Firstly, a hairpin probe, containing target DNA recognition sequence and guanine-rich sequence, was designed to hybridize with the target DNA and form a blunt 3'-terminus DNA duplex. Then, exonuclease III (Exo III) was employed to stepwise hydrolyze the mononucleotides from formed blunt 3'-terminus DNA duplex, releasing the target DNA and guanine-rich sequence. Finally, DNA/Ag NCs fluorescent probe was introduced to hybridize with the guanine-rich sequence, leading to an enhanced fluorescence signal for detection. The proposed method could detect as low as 2.9×10(-10) mol L(-1) HIV-1 DNA and exhibited excellent selectivity against mismatched target DNA. Furthermore, the method possessed perfect recoveries in cells lysate and human serum, showing potential to be used in biological samples. PMID:25863386

  4. Persistent fluorescence-assisted TiO?-xNy-based photocatalyst for gaseous acetaldehyde degradation.

    PubMed

    Li, Huihui; Yin, Shu; Wang, Yuhua; Sato, Tsugio

    2012-07-17

    Photocatalytic technologies were utilized to develop an environment-friendly system that is capable of removing and oxidizing organic pollutants from an air stream. A series of long-afterglow phosphors emitting long lifetime fluorescence was adapted to prepared TiO(2)-based composite photocatalysts for the photodegradation of gas-phase acetaldehyde. Although the photocatalytic reaction by an undoped titania (Degussa P25) was stopped immediately after turning off the irradiation light, the long-afterglow phosphor/nitorogen-doped TiO(2) (TiO(2-x)N(y)) composites maintained the acetaldehyde photodegradation ability even after turning off the light for a long time. This novel photocatalytic property may be attributed to the presence of the long-afterglow phosphor, which can reserve the light energy and generate the persistent fluorescence afterward as the light source for the photocatalytic reaction with the visible-light responsive TiO(2-x)N(y). The substitution of the undoped TiO(2) with TiO(2-x)N(y) was essential to use the fluorescence as a light source for photocatalysis. Such a self-fluorescence-assisted system could enhance the performance of photocatalysts for environmental cleanup. PMID:22681563

  5. Matrix Effects on the Microcystin-LR Fluorescent Immunoassay Based on Optical Biosensor

    PubMed Central

    Long, Feng; Zhu, An-na; Sheng, Jian-Wu; He, Miao; Shi, Han-Chang

    2009-01-01

    Matrix effects on the microcystin-LR fluorescent immunoassay based on the evanescent wave all-fiber immunosensor (EWAI) and their elimination methods were studied. The results indicated that PBS and humic acid did not affect the monitoring of samples under the investigated conditions. When the pH was less than 6 or higher than 8, the fluorescence signals detected by immunosensor systems were obviously reduced with the decrease or increase of pH. When the pH ranged from 6 to 8, IC50 and the linear working range of MC-LR calculated from the detection curves were 1.01?1.04 ?g/L and 0.12?10.5 ?g/L, respectively, which was favourable for an MC-LR immunoassay. Low concentrations of Cu2+ rarely affected the detection performance of MC-LR. When the concentration of CuSO4 was higher than 5 mg/L, the fluorescence signal detected by EWAI clearly decreased, and when the concentration of CuSO4 was 10 mg/L, the fluorescence signal detected was reduced by 70%. The influence of Cu2+ on the immunoassay could effectively be compromised when chelating reagent EDTA was added to the pre-reaction mixture. PMID:22574059

  6. Mercury(II) sensing based on the quenching of fluorescence of CdS-dendrimer nanocomposites.

    PubMed

    Campos, Bruno B; Algarra, Manuel; Alonso, Beatriz; Casado, Carmen M; Esteves da Silva, Joaquim C G

    2009-12-01

    A chemical sensor for mercury(II) (Hg(II)) was developed based on the quenching of the fluorescence of cadmium sulfide (CdS) quantum dots (QDs) coated with polypropylenimine tetrahexacontaamine dendrimer (DAB) generation 5, CdS-DAB nanocomposites. The synthesis and characterization of CdS-DAB nanocomposites by means of EDXA, SEM and steady state luminescence is described. Macroscopic spherical structures are observed by electronic microscopy and the wavelength for the maximum fluorescence emission occurs at 535 nm (excitation at 351 nm). Stern-Volmer plots show a linear response in the range of 1 x 10(-6) to 1 x 10(-5) M with a quenching constant (K(sv)) of 1.5 x 10(5) M(-1). A parallel factor (PARAFAC) analysis model confirmed that Hg(II) alone provokes quenching of the fluorescence. Cu(II) and Pb(II) also quench the fluorescence of CdS-DAB nanocomposites, with a K(sv) = 1.9 x 10(5) M(-1) and K(sv) = 2.2 x 10(4) M(-1), respectively, and Cd(II), Zn(II), Co(II) and Ni(II) have no effect. Ionic strength, in the range from 1.25 x 10(-3) up to 2 M, provokes a shift in the wavelength of the maximum of the emission spectra, from 482 to 677 nm. PMID:19918615

  7. Highly sensitive and selective fluorescence detection of copper (II) ion based on multi-ligand metal chelation.

    PubMed

    Zhang, Shan; Yu, Tao; Sun, Mingtai; Yu, Huan; Zhang, Zhongping; Wang, Suhua; Jiang, Hui

    2014-08-01

    A fluorescent probe was synthesized and demonstrated to be highly selective and sensitive in the reaction with copper (II) ion, generating a large variation of the fluorescence intensity in a dose-response manner. The probe contains a dansyl moiety as fluorophore and a multidentate ligand for copper (II) ion recognition. The reaction of the molecular probe with copper (II) ion proceeds rapidly and irreversibly in a 1 to 1 stoichiometric way, leading to the production of stable copper (II) complex, which subsequently results in the quenching of fluorescence. The detection limit for copper (II) ion was measured to be about 2ppb. It was also shown that the probe has high selectivity for copper (II) ion and good anti-interference ability against other transition metal ions. The herein reported very simple and reliable fluorescence probe could be employed for copper (II) ion detection in many aspects. PMID:24881551

  8. SiGMa: Simple Greedy Matching for Aligning Large Knowledge Bases

    E-print Network

    Pratt, Vaughan

    of large-scale knowledge bases still poses a considerable challenge. Here, we present Simple Greedy and efficiency. 1 Introduction In the last decade, a growing number of large-scale knowledge bases have been as different knowledge bases generally use different terms to represent their entities, and the space

  9. Simple Identity-Based Cryptography with Mediated Xuhua Ding and Gene Tsudik

    E-print Network

    Ding, Xuhua

    Simple Identity-Based Cryptography with Mediated RSA Xuhua Ding and Gene Tsudik Department. Identity-based public key encryption facilitates easy introduction of public key cryptography by allowing. The main prac- tical benefit of identity-based cryptography is in greatly reducing the need for

  10. A one-step selective fluorescence turn-on detection of cysteine and homocysteine based on a facile CdTe/CdS quantum dots-phenanthroline system.

    PubMed

    Chen, Sheng; Tian, Jianniao; Jiang, Yixuan; Zhao, Yanchun; Zhang, Juanni; Zhao, Shulin

    2013-07-17

    In this paper, we report a simple, selective, sensitive and low-cost turn-on photoluminescent sensor for cysteine and homocysteine based on the fluorescence recovery of the CdTe/CdS quantum dots (QDs)-phenanthroline (Phen) system. In the presence of Phen, the fluorescence of QDs could be quenched effectively due to the formation of the non-fluorescent complexes between water-soluble thioglycolic acid (TGA)-capped QDs and Phen. Subsequently, upon addition of cysteine and homocysteine, the strong affinity of cysteine and homocysteine to QDs enables Phen to be dissociated from the surface of QDs and to form stable and luminescent complexes with cysteine and homocysteine in solution. Thus, the fluorescence of CdTe/CdS QDs was recovered gradually. A good linear relationship was obtained from 1.0 to 70.0 ?M for cysteine and from 1.0 to 90.0 ?M for homocysteine, respectively. The detection limits of cysteine and homocysteine were 0.78 and 0.67 ?M, respectively. In addition, the method exhibited a high selectivity for cysteine and homocysteine over the other substances, such as amino acids, thiols, proteins, carbohydrates, etc. More importantly, the sensing system can not only achieve quantitative detection of cysteine and homocysteine but also could be applied in semiquantitative cysteine and homocysteine determination by digital visualization. Therefore, as a proof-of-concept, the proposed method has potential application for the selective detection of cysteine and homocysteine in biological fluids. PMID:23830437

  11. A label-free fluorescent biosensor for ultratrace detection of terbium (?) based on structural conversion of G-quadruplex DNA mediated by ThT and terbium (?).

    PubMed

    Chen, Qiang; Zuo, Junfeng; Chen, Jinfeng; Tong, Ping; Mo, Xiujuan; Zhang, Lan; Li, Jianrong

    2015-10-15

    In this paper, a novel label-free fluorescent biosensor for terbium (?) (Tb(3+)) was proposed based on structural conversion of G-quadruplex DNA mediated by Thioflavin T (ThT) and Tb(3+). In the presence of K(+), ThT could bind to K(+)-stabilized parallel G-quadruplex, giving rise to high fluorescence intensity. Upon the addition of Tb(3+), Tb(3+) could competitively bind to parallel G-quadruplex leading to the structural change, which resulted in fluorescence decrease. The change of fluorescence intensity (?F=F0-F) showed a good linear response toward the concentration of Tb(3+) over the range from 1.0pM to 10.0µM with a limit of detection of 0.55pM. This proposed biosensor was simple and cost-effective in design and in operation with ultrahigh sensitivity and selectivity. Thus, the proposed biosensor could be a promising candidate for monitoring ultratrace Tb(3+) in environment. PMID:26002017

  12. A dinuclear cadmium(II) Schiff base thiocyanato complex: crystal structure and fluorescence.

    PubMed

    Shit, Shyamapada; Sankolli, Ravish; Guru Row, Tayur N

    2014-01-01

    A new dinuclear cadmium(II) complex, [Cd(L)(NCS)]2 (1) has been synthesized using a potentially tetradentate Schiff base ligand HL, 2-((E)-(2-(diethylamino)ethylimino)methyl)-6-methoxyphenol, obtained by the condensation of 2-diethylaminoethylamine and o-vanillin, and characterized by different physicochemical techniques. Crystal structure of the title complex was unambiguously established by single crystal X-ray diffraction which reveals that metal centers are connected by bridging phenolato and chelating methoxy oxygen atoms of the coordinating Schiff bases and embedded in severely distorted octahedral geometries. Fluorescence properties of the ligand and its complex, studied at room temperature indicate that later may serve as strong fluorescent emitter. PMID:24664327

  13. An efficient fluorescent protein-based multifunctional affinity purification approach in mammalian cells.

    PubMed

    Ma, Hanhui; McLean, Janel R; Gould, Kathleen L; McCollum, Dannel

    2014-01-01

    Knowledge of an individual protein's modifications, binding partners, and localization is essential for understanding complex biological networks. We recently described a fluorescent protein-based (mVenus) multifunctional affinity purification (MAP) tag that can be used both to purify a given protein and determine its localization (Ma et al., Mol Cell Proteomics 11:501-511, 2012). MAP purified protein complexes can be further analyzed to identify binding partners and posttranslational modifications by LC-MS/MS. The MAP approach offers rapid FACS-selection of stable clonal cell lines based on the expression level/fluorescence of the MAP-protein fusion. The MAP tag is highly efficient and shows little variability between proteins. Here we describe the general MAP purification method in detail, and show how it can be applied to a specific protein using the human Cdc14B phosphatase as an example. PMID:24943323

  14. A Portable Two-photon Fluorescence Microendoscope Based on a Two-dimensional Scanning Mirror

    Microsoft Academic Search

    Wibool Piyawattanametha; Eric D. Cocker; Robert P. J. Barretto; Juergen C. Jung; Benjamin A. Flusberg; Hyejun Ra; Olav Solgaard; Mark J. Schnitzer

    2007-01-01

    Towards overcoming the size limitations of conventional two-photon fluorescence microscopy for brain imaging in freely moving mice, we introduce a portable laser-scanning microendoscope based on a microelectromechanical systems (MEMS) two-dimensional (2-D) scanning mirror, compound gradient refractive index (GRIN) micro-lenses, and a photonic bandgap fiber (PBF). The microendoscope achieves fast line scanning acquisition rates up to 3.5 kHz and micron-scale imaging

  15. Detection of DNA hybridization based on SnO2 nanomaterial enhanced fluorescence

    Microsoft Academic Search

    Cuiping Gu; Jiarui Huang; Ning Ni; Minqiang Li; Jinhuai Liu

    2008-01-01

    In this paper, enhanced fluorescence emissions were firstly investigated based on SnO2 nanomaterial, and its application in the detection of DNA hybridization was also demonstrated. The microarray of SnO2 nanomaterial was fabricated by the vapour phase transport method catalyzed by patterned Au nanoparticles on a silicon substrate. A probe DNA was immobilized on the substrate with patterned SnO2 nanomaterial, respectively,

  16. Continuous flow fluorescence based immunosensor for the detection of explosives and environmental pollutants

    Microsoft Academic Search

    Paul T. Charles; John C. Bart; Linda L. Judd; Paul R. Gauger; Frances S. Ligler; Anne W. Kusterbeck

    1997-01-01

    A continuous flow fluorescence based immunosensor has been developed at the Naval Research Laboratory as an inexpensive, field portable device to detect environmental pollutants. Detection of environmental pollutants such as explosives [e.g. trinitrotoluene (TNT) and hexahydro-1,3,5 trinitro- 1,3,5-triazine (RDX)[ and polychlorinated biphenyls (PCBs) have been achieved at low level concentrations. The continuous flow immunosensor (CFI) employs antibodies as recognition elements

  17. Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

    PubMed Central

    Lepage, Mathieu L; Mirloup, Antoine; Ripoll, Manon; Stauffert, Fabien; Bodlenner, Anne

    2015-01-01

    Summary The synthesis and photophysical properties of the first examples of iminosugar clusters based on a BODIPY or a pyrene core are reported. The tri- and tetravalent systems designed as molecular probes and synthesized by way of Cu(I)-catalysed azide–alkyne cycloadditions are fluorescent analogues of potent pharmacological chaperones/correctors recently reported in the field of Gaucher disease and cystic fibrosis, two rare genetic diseases caused by protein misfolding.

  18. Development of a fluorescence polarization based assay for histone deacetylase ligand discovery

    PubMed Central

    Mazitschek, Ralph; Patel, Vishal; Wirth, Dyann F.; Clardy, Jon

    2008-01-01

    Histone deacetylases (HDACs) regulate many important physiological processes and the discovery of small molecules that modulate HDAC activity has both academic and clinical relevance. HDAC inhibitors, most notably SAHA, have been pursued as cancer chemotherapeutics but may be useful in treating psychiatric disorders, malaria, and other diseases. Herein, we describe an inexpensive and robust assay, based on fluorescence polarization, for HDAC ligand discovery. The assay is well suited for high-throughput screening and enzyme kinetic studies. PMID:18430569

  19. Development of Ta-based Superconducting Tunnel Junction X-ray Detectors for Fluorescence XAS

    Microsoft Academic Search

    Stephan Friedrich; Owen B. Drury; John Hall; Robin Cantor

    2010-01-01

    We are developing superconducting tunnel junction (STJ) soft X-ray detectors for chemical analysis of dilute samples by fluorescence-detected X-ray absorption spectroscopy (XAS). Our 36-pixel Nb-based STJ spectrometer covers a solid angle Omega\\/4pi~10-3, offers an energy resolution of ~10-20 eV FWHM for energies up to ~1 keV, and can be operated at total count rates of ~106 counts\\/s. For increased quantum

  20. Development of Ta-based Superconducting Tunnel Junction X-ray Detectors for Fluorescence XAS

    Microsoft Academic Search

    S Friedrich; O Drury; J Hall; R Cantor

    2009-01-01

    We are developing superconducting tunnel junction (STJ) soft X-ray detectors for chemical analysis of dilute samples by fluorescence-detected X-ray absorption spectroscopy (XAS). Our 36-pixel Nb-based STJ spectrometer covers a solid angle \\/4 10³, offers an energy resolution of 10-20 eV FWHM for energies up to 1 keV, and can be operated at total count rates of 10 counts\\/s. For increased

  1. A benzobisimidazolium-based fluorescent and colorimetric chemosensor for CO2.

    PubMed

    Guo, Zhiqian; Song, Na Ri; Moon, Jong Hun; Kim, Myounwoo; Jun, Eun Jin; Choi, Jiyoung; Lee, Jin Yong; Bielawski, Christopher W; Sessler, Jonathan L; Yoon, Juyoung

    2012-10-31

    A new sensor for the fluorescent and colorimetric detection of CO(2) is described. The system utilizes fluoride to activate a tetrapropyl benzobisimidazolium salt and operates in the absence of an exogenous base. On the basis of spectroscopic and theoretical analyses, the mode of action of the present system is ascribed to the fluoride-induced formation of an N-heterocyclic carbene intermediate that reacts with CO(2) to form an imidazolium carboxylate. PMID:22931227

  2. Enantioselective Recognition of Chiral Carboxylic Acids by a ?-Amino Acid and 1,10-Phenanthroline Based Chiral Fluorescent Sensor

    PubMed Central

    Zhang, Yonghong; Hu, Fangzhi; Wang, Bin; Zhang, Xiaomei; Liu, Chenjiang

    2015-01-01

    A novel chiral 1,10-phenanthroline-based fluorescent sensor was designed and synthesized from optical active ?-amino acids. It used 1,10-phenanthroline moiety as a fluorescent signaling site and binding site, with optically active ?-amino acids as a chiral barrier site. Notably, the optically active ?-amino acids were obtained by a Lewis base catalyzed hydrosilylation of ?-enamino esters according to our former work. The chiral sensor has been used to conduct the enantioselective recognition of chiral mono and dicarboxylic acids derivatives. Using this fluorescent sensor, a moderate “turn-off” fluorescence-diminishment response towards enantiomer of tartaric acids, and proline was observed. It found that l-enantiomers quench the chiral fluorescence sensor more efficiently than d-enantiomers due to the absolute configuration of the ?-amino acid. PMID:25954953

  3. Seven-color fluorescence imaging of tissue samples based on Fourier spectroscopy and singular value decomposition.

    PubMed

    Tsurui, H; Nishimura, H; Hattori, S; Hirose, S; Okumura, K; Shirai, T

    2000-05-01

    Seven-color analyses of immunofluorescence-stained tissue samples were accomplished using Fourier spectroscopy-based hyperspectral imaging and singular value decomposition. This system consists of a combination of seven fluorescent dyes, three filtersets, an epifluorescence microscope, a spectral imaging system, a computer for data acquisition, and data analysis software. The spectra of all pixels in a multicolor image were taken simultaneously using a Sagnac type interferometer. The spectra were deconvolved to estimate the contribution of each component dye, and individual dye images were constructed based on the intensities of assigned signals. To obtain mixed spectra, three filter sets, i.e., Bl, Gr, and Rd for Alexa488 and Alexa532, for Alexa546, Alexa568, and Alexa594, and for Cy5 and Cy5.5, respectively, were used for simultaneous excitation of two or three dyes. These fluorophores have considerable spectral overlap which precludes their separation by conventional analysis. We resolved their relative contributions to the fluorescent signal by a method involving linear unmixing based on singular value decomposition of the matrices consisting of dye spectra. Analyses of mouse thymic tissues stained with seven different fluorescent dyes provided clear independent images, and any combination of two or three individual dye images could be used for constructing multicolor images. PMID:10769049

  4. An Optimized Fluorescence-Based Bidimensional Immunoproteomic Approach for Accurate Screening of Autoantibodies

    PubMed Central

    Launay, David; Sobanski, Vincent; Dussart, Patricia; Chafey, Philippe; Broussard, Cédric; Duban-Deweer, Sophie; Vermersch, Patrick; Prin, Lionel; Lefranc, Didier

    2015-01-01

    Serological proteome analysis (SERPA) combines classical proteomic technology with effective separation of cellular protein extracts on two-dimensional gel electrophoresis, western blotting, and identification of the antigenic spot of interest by mass spectrometry. A critical point is related to the antigenic target characterization by mass spectrometry, which depends on the accuracy of the matching of antigenic reactivities on the protein spots during the 2D immunoproteomic procedures. The superimposition, based essentially on visual criteria of antigenic and protein spots, remains the major limitation of SERPA. The introduction of fluorescent dyes in proteomic strategies, commonly known as 2D-DIGE (differential in-gel electrophoresis), has boosted the qualitative capabilities of 2D electrophoresis. Based on this 2D-DIGE strategy, we have improved the conventional SERPA by developing a new and entirely fluorescence-based bi-dimensional immunoproteomic (FBIP) analysis, performed with three fluorescent dyes. To optimize the alignment of the different antigenic maps, we introduced a landmark map composed of a combination of specific antibodies. This methodological development allows simultaneous revelation of the antigenic, landmark and proteomic maps on each immunoblot. A computer-assisted process using commercially available software automatically leads to the superimposition of the different maps, ensuring accurate localization of antigenic spots of interest. PMID:26132557

  5. Modelling of diffraction grating based optical filters for fluorescence detection of biomolecules

    PubMed Central

    Kova?i?, M.; Kr?, J.; Lipovšek, B.; Topi?, M.

    2014-01-01

    The detection of biomolecules based on fluorescence measurements is a powerful diagnostic tool for the acquisition of genetic, proteomic and cellular information. One key performance limiting factor remains the integrated optical filter, which is designed to reject strong excitation light while transmitting weak emission (fluorescent) light to the photodetector. Conventional filters have several disadvantages. For instance absorbing filters, like those made from amorphous silicon carbide, exhibit low rejection ratios, especially in the case of small Stokes’ shift fluorophores (e.g. green fluorescent protein GFP with ?exc = 480 nm and ?em = 510 nm), whereas interference filters comprising many layers require complex fabrication. This paper describes an alternative solution based on dielectric diffraction gratings. These filters are not only highly efficient but require a smaller number of manufacturing steps. Using FEM-based optical modelling as a design optimization tool, three filtering concepts are explored: (i) a diffraction grating fabricated on the surface of an absorbing filter, (ii) a diffraction grating embedded in a host material with a low refractive index, and (iii) a combination of an embedded grating and an absorbing filter. Both concepts involving an embedded grating show high rejection ratios (over 100,000) for the case of GFP, but also high sensitivity to manufacturing errors and variations in the incident angle of the excitation light. Despite this, simulations show that a 60 times improvement in the rejection ratio relative to a conventional flat absorbing filter can be obtained using an optimized embedded diffraction grating fabricated on top of an absorbing filter. PMID:25071964

  6. [Remote sensing of chlorophyll fluorescence at airborne level based on unmanned airship platform and hyperspectral sensor].

    PubMed

    Yang, Pei-Qi; Liu, Zhi-Gang; Ni, Zhuo-Ya; Wang, Ran; Wang, Qing-Shan

    2013-11-01

    The solar-induced chlorophyll fluorescence (ChlF) has a close relationship with photosynthetic and is considered as a probe of plant photosynthetic activity. In this study, an airborne fluorescence detecting system was constructed by using a hyperspectral imager on board an unmanned airship. Both Fraunhofer Line Discriminator (FLD) and 3FLD used to extract ChlF require the incident solar irradiance, which is always difficult to receive at airborne level. Alternative FLD (aFLD) can overcome the problem by selecting non-fluorescent emitter in the image. However, aFLD is based on the assumption that reflectance is identical around the Fraunhofer line, which is not realistic. A new method, a3FLD, is proposed, which assumes that reflectance varies linearly with the wavelength around Fraunhofer line. The result of simulated data shows that ChlF retrieval error of a3FLD is significantly lower than that of aFLD when vegetation reflectance varies near the Fraunhofer line. The results of hyperspectral remote sensing data with the airborne fluorescence detecting system show that the relative values of retrieved ChlF of 5 kinds of plants extracted by both aFLD and a3FLD are consistent with vegetation growth stage and the ground-level ChlF. The ChlF values of aFLD are about 15% greater than a3FLD. In addition, using aFLD, some non-fluorescent objects have considerable ChlF value, while a3FLD can effectively overcome the problem. PMID:24555390

  7. Fluorescence Intensity- and Lifetime-Based Glucose Sensing Using Glucose/Galactose-Binding Protein

    PubMed Central

    Pickup, John C.; Khan, Faaizah; Zhi, Zheng-Liang; Coulter, Jonathan; Birch, David J. S.

    2013-01-01

    We review progress in our laboratories toward developing in vivo glucose sensors for diabetes that are based on fluorescence labeling of glucose/galactose-binding protein. Measurement strategies have included both monitoring glucose-induced changes in fluorescence resonance energy transfer and labeling with the environmentally sensitive fluorophore, badan. Measuring fluorescence lifetime rather than intensity has particular potential advantages for in vivo sensing. A prototype fiber-optic-based glucose sensor using this technology is being tested.Fluorescence technique is one of the major solutions for achieving the continuous and noninvasive glucose sensor for diabetes. In this article, a highly sensitive nanostructured sensor is developed to detect extremely small amounts of aqueous glucose by applying fluorescence energy transfer (FRET). A one-pot method is applied to produce the dextran-fluorescein isothiocyanate (FITC)-conjugating mesoporous silica nanoparticles (MSNs), which afterward interact with the tetramethylrhodamine isothiocyanate (TRITC)-labeled concanavalin A (Con A) to form the FRET nanoparticles (FITC-dextran-Con A-TRITC@MSNs). The nanostructured glucose sensor is then formed via the self-assembly of the FRET nanoparticles on a transparent, flexible, and biocompatible substrate, e.g., poly(dimethylsiloxane). Our results indicate the diameter of the MSNs is 60 ± 5 nm. The difference in the images before and after adding 20 ?l of glucose (0.10 mmol/liter) on the FRET sensor can be detected in less than 2 min by the laser confocal laser scanning microscope. The correlation between the ratio of fluorescence intensity, I(donor)/I(acceptor), of the FRET sensor and the concentration of aqueous glucose in the range of 0.04–4 mmol/liter has been investigated; a linear relationship is found. Furthermore, the durability of the nanostructured FRET sensor is evaluated for 5 days. In addition, the recorded images can be converted to digital images by obtaining the pixels from the resulting matrix using Matlab image processing functions. We have also studied the in vitro cytotoxicity of the device. The nanostructured FRET sensor may provide an alternative method to help patients manage the disease continuously. PMID:23439161

  8. A Practical Solution for 77 K Fluorescence Measurements Based on LED Excitation and CCD Array Detector.

    PubMed

    Lamb, Jacob; Forfang, Kristin; Hohmann-Marriott, Martin

    2015-01-01

    The fluorescence emission spectrum of photosynthetic microorganisms at liquid nitrogen temperature (77 K) provides important insights into the organization of the photosynthetic machinery of bacteria and eukaryotes, which cannot be observed at room temperature. Conventionally, to obtain such spectra, a large and costly table-top fluorometer is required. Recently portable, reliable, and largely maintenance-free instruments have become available that can be utilized to accomplish a wide variety of spectroscopy-based measurements in photosynthesis research. In this report, we show how to build such an instrument in order to record 77K fluorescence spectra. This instrument consists of a low power monochromatic light-emitting diode (LED), and a portable CCD array based spectrometer. The optical components are coupled together using a fiber optic cable, and a custom made housing that also supports a dewar flask. We demonstrate that this instrument facilitates the reliable determination of chlorophyll fluorescence emission spectra for the cyanobacterium Synechocystis sp. PCC 6803, and the green alga Chlamydomonas reinhardtii. PMID:26177548

  9. A Practical Solution for 77 K Fluorescence Measurements Based on LED Excitation and CCD Array Detector

    PubMed Central

    Lamb, Jacob; Forfang, Kristin; Hohmann-Marriott, Martin

    2015-01-01

    The fluorescence emission spectrum of photosynthetic microorganisms at liquid nitrogen temperature (77 K) provides important insights into the organization of the photosynthetic machinery of bacteria and eukaryotes, which cannot be observed at room temperature. Conventionally, to obtain such spectra, a large and costly table-top fluorometer is required. Recently portable, reliable, and largely maintenance-free instruments have become available that can be utilized to accomplish a wide variety of spectroscopy-based measurements in photosynthesis research. In this report, we show how to build such an instrument in order to record 77K fluorescence spectra. This instrument consists of a low power monochromatic light-emitting diode (LED), and a portable CCD array based spectrometer. The optical components are coupled together using a fiber optic cable, and a custom made housing that also supports a dewar flask. We demonstrate that this instrument facilitates the reliable determination of chlorophyll fluorescence emission spectra for the cyanobacterium Synechocystis sp. PCC 6803, and the green alga Chlamydomonas reinhardtii. PMID:26177548

  10. A Cu2+-selective fluorescent chemosensor based on BODIPY with two pyridine ligands and logic gate

    NASA Astrophysics Data System (ADS)

    Huang, Liuqian; Zhang, Jing; Yu, Xiaoxiu; Ma, Yifan; Huang, Tianjiao; Shen, Xi; Qiu, Huayu; He, Xingxing; Yin, Shouchun

    2015-06-01

    A novel near-infrared fluorescent chemosensor based on BODIPY (Py-1) has been synthesized and characterized. Py-1 displays high selectivity and sensitivity for sensing Cu2+ over other metal ions in acetonitrile. Upon addition of Cu2+ ions, the maximum absorption band of Py-1 in CH3CN displays a red shift from 603 to 608 nm, which results in a visual color change from pink to blue. When Py-1 is excited at 600 nm in the presence of Cu2+, the fluorescent emission intensity of Py-1 at 617 nm is quenched over 86%. Notably, the complex of Py-1-Cu2+ can be restored with the introduction of EDTA or S2-. Consequently, an IMPLICATION logic gate at molecular level operating in fluorescence mode with Cu2+ and S2- as chemical inputs can be constructed. Finally, based on the reversible and reproducible system, a nanoscale sequential memory unit displaying "Writing-Reading-Erasing-Reading" functions can be integrated.

  11. Long term response of a Concanavalin-A based fluorescence glucose sensing assay

    NASA Astrophysics Data System (ADS)

    Locke, Andrea K.; Cummins, Brian M.; Abraham, Alexander A.; Coté, Gerard L.

    2015-03-01

    Competitive binding assays comprised of the protein Concanavalin A (ConA) have shown potential for use in continuous glucose monitoring devices. However, its time-dependent, thermal instability can impact the lifetime of these ConA based assays. In an attempt to design sensors with longer in vivo lifetimes, different groups have immobilized the protein to various surfaces. For example, Ballerstadt et al. have shown that immobilizing ConA onto the interior of a micro-dialysis membrane and allowing dextran to be freely suspended within solution allowed for successful in vivo glucose sensing up to 16 days. This work explores the glucose response of an assay comprised of modified ConA and a single fluorescently labeled competing ligand in free solution to increase the in vivo sensing lifetime without immobilization,. The behavior of this assay in the presence of varying glucose concentrations is monitored via fluorescence anisotropy over a 30 day period.

  12. A dansyl based fluorescence chemosensor for Hg(2+) and its application in the complicated environment samples.

    PubMed

    Zhou, Shuai; Zhou, Ze-Quan; Zhao, Xuan-Xuan; Xiao, Yu-Hao; Xi, Gang; Liu, Jin-Ting; Zhao, Bao-Xiang

    2015-09-01

    We have developed a novel fluorescent chemosensor (DAM) based on dansyl and morpholine units for the detection of mercury ion with excellent selectivity and sensitivity. In the presence of Hg(2+) in a mixture solution of HEPES buffer (pH 7.5, 20mM) and MeCN (2/8, v/v) at room temperature, the fluorescence of DAM was almost completely quenched from green to colorless with fast response time. Moreover, DAM also showed its excellent anti-interference capability even in the presence of large amount of interfering ions. It is worth noting that DAM could be used to detect Hg(2+) specifically in the Yellow River samples, which significantly implied the potential applications of DAM in the complicated environment samples. PMID:25911159

  13. A simple birth-death-migration individual-based model for biofilm development

    E-print Network

    Paris-Sud XI, Université de

    A simple birth-death-migration individual-based model for biofilm development Nabil Mabrouk- congnized to play an important role in microbial biofilm formation. In this paper we we investigate using an individual-based model how these processes interplay to yield complex biofilm spatial patterns. 1

  14. Design of a simple high-power-factor rectifier based on the flyback converter

    Microsoft Academic Search

    Robert Erickson; Michael Madigan; Sigmund Singer

    1990-01-01

    An equivalent circuit model for the discontinuous conduction mode flyback converter based on the loss-free resistor concept is presented. This simple model correctly describes the basic power processing properties of the converter, including input port resistor emulation, output port power source characteristics, and control characteristics. Based on this model, steady-state design equations are described and are used in a design

  15. Fluorescence-based sensing of p-nitrophenol and p-nitrophenyl substituent organophosphates.

    PubMed

    Paliwal, Sheetal; Wales, Melinda; Good, Theresa; Grimsley, Janet; Wild, James; Simonian, Aleksandr

    2007-07-16

    A novel detection method for organophosphate neurotoxins has been described, based on the fluorescence quenching of a Coumarin derivative. These dyes are similar in structure to some organophosphates (OPs), and they fluoresce in the blue-green region of the spectra. This methodology has been utilized for the detection of organophosphates whose hydrolysis product is p-nitrophenol by using an enzyme, organophosphorus hydrolase (OPH). Coumarin1 in the presence of p-nitrophenol results in a quenching of fluorescence, providing a direct measure of the concentration of p-nitrophenol present in the sample. The decrease in fluorescence intensity is proportional to the paraoxon concentration in the range of 7.0x10(-7)-1.7x10(-4) M. The specificity of this sensing application for p-nitrophenyl substituent OPs has also been demonstrated. OPs are a class of synthetic organic pesticides which generally have a short residual life and can cause numerous acute and chronic health effects. They have been an integral part of the agricultural industry for the past several decades due to their target specificities and selectable toxicities. The toxic nature of these compounds can be attributed to the species-specific inhibition of acetylcholinesterase (AChE), an important enzyme responsible for the regeneration of neural synaptic function. In addition to their wide agricultural and urban usage, they have also been exploited for the development of neurological chemical warfare agents. Currently available technologies for OP detection include sol-gel thin films, screen printed electrodes, acoustic patterning, gas chromatography-mass spectrometry, and various other intricate techniques that have limited field applicabilities. This optically-based approach promises much simpler and more direct detection capabilities. PMID:17616234

  16. Characterization of the chemical composition of polyisobutylene-based oil-soluble dispersants by fluorescence.

    PubMed

    Pirouz, Solmaz; Wang, Yulin; Chong, J Michael; Duhamel, Jean

    2014-04-10

    A novel methodology based on fluorescence quenching measurements is introduced to determine quantitatively the amine content of polyisobutylene succinimide (PIBSI) dispersants used as engine oil-additives. To this end, a series of five PIBSI dispersants were prepared by reacting 2 mol equiv of polyisobutylene succinic anhydride (PIBSA) with 1 mol equiv of hexamethylenediamine (HMDA), diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine to yield the corresponding b-PIBSI dispersants. After having demonstrated that the presence of hydrogen bonds between the polyamine linker and the succinimide carbonyls of the dispersants prevents the quantitative analysis of the (1)H NMR and FTIR spectra of the dispersants to determine their chemical composition, alternative procedures based on gel permeation chromatography (GPC) and fluorescence quenching were implemented to estimate the amine content of the b-PIBSI dispersants. Taking advantage of the doubling in size that occurs when 2 mol of PIBSA are reacted with 1 mol of HMDA, a combination of GPC and FTIR was employed to follow how the chemical composition and molecular weight distribution of the polymers produced evolved with the reaction of PIBSA and HMDA mixed at different molar ratios. These experiments provided the PIBSA-to-HMDA molar ratio yielding the largest b-PIBSI dispersants and this molar ratio was then selected to prepare the four other dispersants. Having prepared five b-PIBSI dispersants with well-defined secondary amine content, the fluorescence of the succinimide groups was found to decrease with increasing number of secondary amines present in the polyamine linker. This result suggests that fluorescence quenching provides a valid method to determine the chemical composition of b-PIBSI dispersants which is otherwise difficult to characterize by standard (1)H NMR and FTIR spectroscopies. PMID:24628080

  17. Scaling of Space-Based Measurements of Sun Induced Chlorophyll Fluorescence to Global Gross Primary Production

    NASA Astrophysics Data System (ADS)

    Voigt, Maximilian; Guanter, Luis; Jung, Martin

    2015-04-01

    Gross Primary Productivity (GPP) is the amount of atmospheric carbon dioxide taken up by ecosystems via photosynthesis. This is the single largest flux of the global land carbon budget and makes plants an important component of the global climate system. The uncertainties of modeling terrestrial global GPP are large, partly because of lacking direct global measurements. The measurement of sun induced chlorophyll fluorescence (SIF), which is linked to photosynthesis could be therefore of vital importance for the modeling of GPP. The fluorescence signal, whose maximum lies in a spectral range of 650 nm - 800 nm, can be monitored globally with the GOME-2 instrument on board of the Metop-A satellite which has been launched in October 2006. Although the link between photosynthesis and fluorescence at the leaf scale is relatively well known based on lab- and field-experiments, the relationship at the canopy level and for the coarse spatial resolutions provided by space-borne instruments (of the order of 10 km-100 km) is still uninvestigated. An inspection of the functional relationship between remotely sensed SIF and a state of the art statistically upscaled GPP product on grid box basis (0.5° resolution) reveals good linear relations almost everywhere on the globe. However changes of tlhe slopes between pixels are observed, which are expected to be caused by canopy related properties. These can be structural effects, which alter the outgoing fluorescence signal by scattering and reabsorbtion, or changing efficiencies of photosynthesis and fluorescence. As estimates of these quantities are missing on a global scale, a set of meteorological variables (temperature, precipitation, etc.) and the clumping index are used as proxy variables. The changing relationship is then modeled with a model based partitioning algorithm. It can be shown that the model complexity can be drastically reduced without a significant loss of model performance by going from a per-pixel-fitting to the model based partitioning approach. As a result of this study we provide global estimates of GPP based on SIF observation on a monthly basis.

  18. A universal fluorescence sensing strategy based on biocompatible graphene quantum dots and graphene oxide for the detection of DNA

    NASA Astrophysics Data System (ADS)

    Qian, Z. S.; Shan, X. Y.; Chai, L. J.; Ma, J. J.; Chen, J. R.; Feng, H.

    2014-05-01

    A novel and efficient fluorescence sensing platform based on biocompatible graphene quantum dots and graphene oxide was established. It showed high selectivity and sensitivity for DNA detection.A novel and efficient fluorescence sensing platform based on biocompatible graphene quantum dots and graphene oxide was established. It showed high selectivity and sensitivity for DNA detection. Electronic supplementary information (ESI) available: XPS, FTIR spectra and experimental details. See DOI: 10.1039/c3nr06583a

  19. Multipoint parallel excitation and CCD-based imaging system for high-throughput fluorescence detection of biochip micro-arrays

    Microsoft Academic Search

    D. S. Mehta; C. Y. Lee; A. Chiou

    2001-01-01

    We report the development and the characterization of a multipoint parallel excitation and CCD-based imaging system for high-throughput fluorescence detection of biochip micro-arrays. A two-dimensional array of (19×19) points with uniform intensity distribution, generated by a holographic array generator, was used for parallel excitation of two-dimensional micro-arrays of fluorescence samples. A CCD-based imaging system was used for high-throughput parallel detection

  20. Fluorescence-based proxies for lignin in freshwater dissolved organic matter

    USGS Publications Warehouse

    Hernes, Peter J.; Bergamaschi, Brian A.; Eckard, Robert S.; Spencer, Robert G.M.

    2009-01-01

    Lignin phenols have proven to be powerful biomarkers in environmental studies; however, the complexity of lignin analysis limits the number of samples and thus spatial and temporal resolution in any given study. In contrast, spectrophotometric characterization of dissolved organic matter (DOM) is rapid, noninvasive, relatively inexpensive, requires small sample volumes, and can even be measured in situ to capture fine-scale temporal and spatial detail of DOM cycling. Here we present a series of cross-validated Partial Least Squares models that use fluorescence properties of DOM to explain up to 91% of lignin compositional and concentration variability in samples collected seasonally over 2 years in the Sacramento River/San Joaquin River Delta in California, United States. These models were subsequently used to predict lignin composition and concentration from fluorescence measurements collected during a diurnal study in the San Joaquin River. While modeled lignin composition remained largely unchanged over the diurnal cycle, changes in modeled lignin concentrations were much greater than expected and indicate that the sensitivity of fluorescence-based proxies for lignin may prove invaluable as a tool for selecting the most informative samples for detailed lignin characterization. With adequate calibration, similar models could be used to significantly expand our ability to study sources and processing of DOM in complex surface water systems.

  1. Ion track reconstruction in 3D using alumina-based fluorescent nuclear track detectors

    E-print Network

    Niklas, Martin; Akselrod, Mark S; Abollahi, Amir; Jäkel, Oliver; Greilich, Steffen

    2013-01-01

    Fluorescent nuclear track detectors (FNTDs) based on Al2O3:C,Mg single crystal combined with confocal microscopy provide 3D information on ion tracks with a resolution only limited by light diffraction. FNTDs are also ideal substrates to be coated with cells to engineer cell-fluorescent ion track hybrid detectors. This radiobiological tool enables a novel platform linking cell responses to physical dose deposition on a sub-cellular level in proton and heavy ion therapies. To achieve spatial correlation between single ion hits in the cell coating and its biological response the ion traversals have to be reconstructed in 3D using the depth information gained by the FNTD read-out. FNTDs were coated with a confluent human lung adenocarcinoma epithelial cell layer. Carbon ion irradiation of the hybrid detector was performed perpendicular and angular to the detector surface. In-situ imaging of the fluorescently labeled cell layer and the FNTD was performed in a sequential read-out. Making use of the trajectory info...

  2. Optical tweezers and non-ratiometric fluorescent-dye-based studies of respiration in sperm mitochondria

    NASA Astrophysics Data System (ADS)

    Chen, Timothy; Shi, Linda Z.; Zhu, Qingyuan; Chandsawangbhuwana, Charlie; Berns, Michael W.

    2011-04-01

    The purpose of this study is to investigate how the mitochondrial membrane potential affects sperm motility using laser tweezers and a non-ratiometric fluorescent probe, DiOC6(3). A 1064 nm Nd:YVO4 continuous wave laser was used to trap motile sperm at a power of 450 mW in the trap spot. Using customized tracking software, the curvilinear velocity (VCL) and the escape force from the laser tweezers were measured. Human (Homo sapiens), dog (Canis lupis familiaris) and drill (Mandrillus leucophaeus) sperm were treated with DiOC6(3) to measure the membrane potential in the mitochondria-rich sperm midpieces. Sperm from all three species exhibited an increase in fluorescence when treated with the DiOC6(3). When a cyanide inhibitor (CCCP) of aerobic respiration was applied, sperm of all three species exhibited a reduction in fluorescence to pre-dye levels. With respect to VCL and escape force, the CCCP had no effect on dog or human sperm, suggesting a major reliance upon anaerobic respiration (glycolysis) for ATP in these two species. Based on the preliminary study on drill sperm, CCCP caused a drop in the VCL, suggesting potential reliance on both glycolysis and aerobic respiration for motility. The results demonstrate that optical trapping in combination with DiOC6(3) is an effective way to study sperm motility and energetics.

  3. Developing a Fluorescence-based Approach to Screening for Macromolecule Crystallization Conditions

    PubMed Central

    Pusey, Marc L.

    2011-01-01

    Current macromolecule crystallization screening methods rely on the random testing of crystallization conditions, in the hope that one or more will yield positive results, crystals. Most plate outcomes are either clear or precipitated solutions, which results are routinely discarded by the experimenter. However, many of these may in fact be close to crystallization conditions, which fact is obscured by the nature of the apparent outcome. We are developing a fluorescence-based approach to the determination of crystallization conditions, which approach can also be used to assess conditions that may be close to those that would give crystals. The method uses measurements of fluorescence anisotropy and intensity. The method was first tested using model proteins, with likely outcomes as determined by fluorescence measurements where the plate data showed either clear or precipitated solutions being subjected to optimization screening. The results showed a ~83% increase in the number of crystallization conditions. The method was then tried as the sole screening method with a number of test proteins. In every case at least one or more crystallization conditions were found, and it is estimated that ~53% of these would not have been found using a plate screen. PMID:21792347

  4. Fluorescence-based proxies for lignin in freshwater dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Hernes, Peter J.; Bergamaschi, Brian A.; Eckard, Robert S.; Spencer, Robert G. M.

    2009-12-01

    Lignin phenols have proven to be powerful biomarkers in environmental studies; however, the complexity of lignin analysis limits the number of samples and thus spatial and temporal resolution in any given study. In contrast, spectrophotometric characterization of dissolved organic matter (DOM) is rapid, noninvasive, relatively inexpensive, requires small sample volumes, and can even be measured in situ to capture fine-scale temporal and spatial detail of DOM cycling. Here we present a series of cross-validated Partial Least Squares models that use fluorescence properties of DOM to explain up to 91% of lignin compositional and concentration variability in samples collected seasonally over 2 years in the Sacramento River/San Joaquin River Delta in California, United States. These models were subsequently used to predict lignin composition and concentration from fluorescence measurements collected during a diurnal study in the San Joaquin River. While modeled lignin composition remained largely unchanged over the diurnal cycle, changes in modeled lignin concentrations were much greater than expected and indicate that the sensitivity of fluorescence-based proxies for lignin may prove invaluable as a tool for selecting the most informative samples for detailed lignin characterization. With adequate calibration, similar models could be used to significantly expand our ability to study sources and processing of DOM in complex surface water systems.

  5. Sensitivity of Ag:DNA fluorescence to single base mutations of hairpin strands

    NASA Astrophysics Data System (ADS)

    Gwinn, Elisabeth; Hassanzadeh, Rameen; O'Neill, Patrick; Fygenson, Deborah

    2010-03-01

    DNA strands can stabilize fluorescent silver clusters composed of just a few atoms [1]. The small size of these photon emitters and their formation in single-stranded DNA [2] give Ag:DNA emitters promise for use in optically-active, self-assembled DNA nanostructures. Exploiting this promise requires an understanding of how fluorophore color relates to the sequence and conformation of the host DNA strand. Here we examine the optical properties of Ag:DNA solutions for a family of DNA hairpins that differ by single base mutations in the hairpin loop. Specific mutations result in spectral redistribution of the fluorescence and large changes in brightness, pointing to geometric control as a means to select specific emitter species.[4pt] [1] J.T. Petty, J. Zheng, N.V. Hud and R.M. Dickson, ``DNA-templated Ag nanocluster formation,'' J. Am. Chem. Soc, 126, 5207 (2004).[0pt] [2] E.G. Gwinn, P. O'Neill, A. Guerrero, D. Bouwmeester and D.K. Fygenson, ``Sequence-dependent fluorescence from DNA-hosted silver nanoclusters,'' Advanced Materials 20, 279 (2008).

  6. Effectiveness of fluorescence-based methods to detect in situ demineralization and remineralization on smooth surfaces.

    PubMed

    Moriyama, C M; Rodrigues, J A; Lussi, A; Diniz, M B

    2014-01-01

    This study aimed to evaluate the effectiveness of fluorescence-based methods (DIAGNOdent, LF; DIAGNOdent pen, LFpen, and VistaProof fluorescence camera, FC) in detecting demineralization and remineralization on smooth surfaces in situ. Ten volunteers wore acrylic palatal appliances, each containing 6 enamel blocks that were demineralized for 14 days by exposure to a 20% sucrose solution and 3 of them were remineralized for 7 days with fluoride dentifrice. Sixty enamel blocks were evaluated at baseline, after demineralization and 30 blocks after remineralization by two examiners using LF, LFpen and FC. They were submitted to surface microhardness (SMH) and cross-sectional microhardness analysis. The integrated loss of surface hardness (?KHN) was calculated. The intraclass correlation coefficient for interexaminer reproducibility ranged from 0.21 (FC) to 0.86 (LFpen). SMH, LF and LFpen values presented significant differences among the three phases. However, FC fluorescence values showed no significant differences between the demineralization and remineralization phases. Fluorescence values for baseline, demineralized and remineralized enamel were, respectively, 5.4 ± 1.0, 9.2 ± 2.2 and 7.0 ± 1.5 for LF; 10.5 ± 2.0, 15.0 ± 3.2 and 12.5 ± 2.9 for LFpen, and 1.0 ± 0.0, 1.0 ± 0.1 and 1.0 ± 0.1 for FC. SMH and ?KHN showed significant differences between demineralization and remineralization phases. There was a negative and significant correlation between SMH and LF and LFpen in the remineralization phase. In conclusion, LF and LFpen devices were effective in detecting demineralization and remineralization on smooth surfaces provoked in situ. PMID:24902775

  7. Invertase-nanogold clusters decorated plant membranes for fluorescence-based sucrose sensor.

    PubMed

    Bagal-Kestwal, Dipali; Kestwal, Rakesh Mohan; Chiang, Been-Huang

    2015-01-01

    In the present study, invertase-mediated nanogold clusters were synthesized on onion membranes, and their application for sucrose biosensor fabrication was investigated. Transmission electron microscopy revealed free nanoparticles of various sizes (diameter ~5 to 50 nm) along with clusters of nanogold (~95 to 200 nm) on the surface of inner epidermal membranes of onions (Allium cepa L.). Most of the polydispersed nanoparticles were spherical, although some were square shaped, triangular, hexagonal or rod-shaped. Ultraviolet-visible spectrophotometric observations showed the characteristic peak for nanoparticles decorated invertase-onion membrane at approximately 301 nm. When excited at 320 nm in the presence of sucrose, the membranes exhibited a photoemission peak at 348 nm. The fluorescence lifetime of this nanogold modified onion membrane was 6.20 ns, compared to 2.47 ns for invertase-onion membrane without nanogold. Therefore, a sucrose detection scheme comprised of an invertase/nanogold decorated onion membrane was successfully developed. This fluorescent nanogold-embedded onion membrane drop-test sensor exhibited wide acidic to neutral working pH range (4.0-7.0) with a response time 30 seconds (<1 min). The fabricated quenching-based probe had a low detection limit (2x10(-9) M) with a linear dynamic range of 2.25x10(-9) to 4.25x10(-8) M for sensing sucrose. A microplate designed with an enzyme-nanomaterial-based sensor platform exhibited a high compliance, with acceptable percentage error for the detection of sucrose in green tea samples in comparison to a traditional method. With some further, modifications, this fabricated enzyme-nanogold onion membrane sensor probe could be used to estimate glucose concentrations for a variety of analytical samples. Graphical abstract Synthesis and characterization of invertase assisted nanogold clusters on onion membranes and their application for fluorescence-based sucrose sensor. PMID:25886379

  8. A novel fluorescence-based assay for the rapid detection and quantification of cellular deoxyribonucleoside triphosphates

    PubMed Central

    Wilson, Peter M.; LaBonte, Melissa J.; Russell, Jared; Louie, Stan; Ghobrial, Andrew A.; Ladner, Robert D.

    2011-01-01

    Current methods for measuring deoxyribonucleoside triphosphates (dNTPs) employ reagent and labor-intensive assays utilizing radioisotopes in DNA polymerase-based assays and/or chromatography-based approaches. We have developed a rapid and sensitive 96-well fluorescence-based assay to quantify cellular dNTPs utilizing a standard real-time PCR thermocycler. This assay relies on the principle that incorporation of a limiting dNTP is required for primer-extension and Taq polymerase-mediated 5–3? exonuclease hydrolysis of a dual-quenched fluorophore-labeled probe resulting in fluorescence. The concentration of limiting dNTP is directly proportional to the fluorescence generated. The assay demonstrated excellent linearity (R2?>?0.99) and can be modified to detect between ?0.5 and 100?pmol of dNTP. The limits of detection (LOD) and quantification (LOQ) for all dNTPs were defined as <0.77 and <1.3?pmol, respectively. The intra-assay and inter-assay variation coefficients were determined to be <4.6% and <10%, respectively with an accuracy of 100?±?15% for all dNTPs. The assay quantified intracellular dNTPs with similar results obtained from a validated LC–MS/MS approach and successfully measured quantitative differences in dNTP pools in human cancer cells treated with inhibitors of thymidylate metabolism. This assay has important application in research that investigates the influence of pathological conditions or pharmacological agents on dNTP biosynthesis and regulation. PMID:21576234

  9. Anion recognition by simple chromogenic and chromo-fluorogenic salicylidene Schiff base or reduced-Schiff base receptors

    NASA Astrophysics Data System (ADS)

    Dalapati, Sasanka; Jana, Sankar; Guchhait, Nikhil

    2014-08-01

    This review contains extensive application of anion sensing ability of salicylidene type Schiff bases and their reduced forms having various substituents with respect to phenolic sbnd OH group. Some of these molecular systems behave as receptor for recognition or sensing of various anions in organic or aqueous-organic binary solvent mixture as well as in the solid supported test kits. Development of Schiff base or reduced Schiff base receptors for anion recognition event is commonly based on the theory of hydrogen bonding interaction or deprotonation of phenolic -OH group. The process of charge transfer (CT) or inhibition of excited proton transfer (ESIPT) or followed by photo-induced electron transfer (PET) lead to naked-eye color change, UV-vis spectral change, chemical shift in the NMR spectra and fluorescence spectral modifications. In this review we have tried to discuss about the anion sensing properties of Schiff base or reduced Schiff base receptors.

  10. Establishment of a New Cell-Based Assay To Measure the Activity of Sweeteners in Fluorescent Food Extracts

    PubMed Central

    2011-01-01

    Taste receptors have been defined at the molecular level in the past decade, and cell-based assays have been developed using cultured cells heterologously expressing these receptors. The most popular approach to detecting the cellular response to a tastant is to measure changes in intracellular Ca2+ concentration using Ca2+-sensitive fluorescent dyes. However, this method cannot be applied to food-derived samples that contain fluorescent substances. To establish an assay system that would be applicable to fluorescent samples, we tested the use of Ca2+-sensitive photoproteins, such as aequorin and mitochondrial clytin-II, as Ca2+ indicators in a human sweet taste receptor assay. Using these systems, we successfully detected receptor activation in response to sweetener, even when fluorescent compounds coexisted. This luminescence-based assay will be a powerful tool to objectively evaluate the sweetness of food-derived samples even at an industry level. PMID:21981007

  11. 5-(Pyren-1-yl)uracil as a base-discriminating fluorescent nucleobase in pyrrolidinyl peptide nucleic acids.

    PubMed

    Boonlua, Chalothorn; Vilaivan, Chotima; Wagenknecht, Hans-Achim; Vilaivan, Tirayut

    2011-12-01

    A pyrene-labeled uridine (U(Py)) monomer for a pyrrolidinyl peptide nucleic acid with an alternating proline/2-aminocyclopentanecarboxylic acid backbone (acpcPNA) was synthesized and incorporated into the PNA. The U(Py) base in acpcPNA could specifically recognize the base A in its complementary DNA strand as determined by thermal denaturation (T(m)) experiments. The fluorescence of the U(Py)-containing single-stranded acpcPNA was very weak in aqueous buffer. In the presence of a complementary DNA target, the fluorescence was enhanced significantly (2.7-41.9 folds, depending on sequences). The fluorescence enhancement was specific to the pairing between U(Py) and dA, making the U(Py)-modified acpcPNA useful as a hybridization-responsive fluorescence probe for DNA-sequence determination. PMID:21976408

  12. A fluorescence-based high throughput assay for the determination of small molecule–human serum albumin protein binding

    PubMed Central

    McCallum, Megan M.; Pawlak, Alan J.; Shadrick, William R.; Simeonov, Anton; Jadhav, Ajit; Yasgar, Adam; Maloney, David J.; Arnold, Leggy A.

    2014-01-01

    Herein, we describe the development of a fluorescence-based high throughput assay to determine the small molecule binding towards human serum albumin (HSA). This innovative competition assay is based on the use of a novel fluorescent small molecule Red Mega 500 with unique spectroscopic and binding properties. The commercially available probe displays a large fluorescence intensity difference between the protein-bound and protein-unbound state. The competition of small molecules for HSA binding in the presence of probe resulted in low fluorescence intensities. The assay was evaluated with the LOPAC small molecule library of 1280 compounds identifying known high protein binders. The small molecule competition of HSA–Red Mega 500 binding was saturable at higher compound concentrations and exhibited IC50 values between 3–24 ?M. The compound affinity towards HSA was confirmed by isothermal titration calorimetry indicating that the new protein binding assay is a valid high throughput assay to determine plasma protein binding. PMID:24390461

  13. Design of ultrasensitive DNA-based fluorescent pH sensitive nanodevices.

    PubMed

    Halder, Saheli; Krishnan, Yamuna

    2015-06-14

    Here we tune the pH sensitivity of a DNA-based conformational switch, called the I-switch, to yield a set of fluorescent pH sensitive nanodevices with a collective, expanded pH sensing regime from 5.3 to 7.5. The expanded pH regime of this new family of I-switches originates from a dramatic improvement in the overall percentage signal change in response to pH of these nanodevices. PMID:25990365

  14. Synthesis and characterization of a novel waterborne stilbene-based polyurethane fluorescent brightener

    Microsoft Academic Search

    Xian Hai Hu; Xing Yuan Zhang; Jia Bin Dai

    2011-01-01

    A novel waterborne stilbene-based polyurethane fluorescent brightener dispersion WPU-VBL was synthesized by incorporating chemically disodium 4,4?-bis[(4-anilino-6-hydroxyethylamino-1,3,5-triazin-2-yl)amino]stilbene-2,2?-disulphonate (VBL) into the polyurethane chain using isophorone diisocyanate, poly(propylene glycol) and 2,2-dimethylol propionic acid. The structure of WPU-VBL was confirmed by means of Fourier transform infrared spectroscopy. The UV–vis absorption analysis showed a hypsochromic shift of 16nm when VBL was blocked into polyurethane chain.

  15. Ratiometric fluorescent chemosensor for fluoride ion based on inhibition of excited state intramolecular proton transfer.

    PubMed

    Gupta, Akul Sen; Paul, Kamaldeep; Luxami, Vijay

    2015-03-01

    ESIPT based benzimidazole derivative has been synthesized and investigated their photophysical behavior towards various anions. The probe 2 has been used for selective estimation of F(-) ions as compared to other anions and signaled the binding event through formation of new absorption band at 360nm and emission band at 420nm. The probe 2 showed fluorescence behavior towards fluoride ions through hydrogen bonding interactions and restricted the ESIPT emission at 540nm from OH to nitrogen of benzimidazole moiety to release its enol emission at 420nm. PMID:25463052

  16. In vivo imaging and biochemical characterization of protease function using fluorescent activity-based probes

    PubMed Central

    Edgington, Laura E.; Bogyo, Matthew

    2013-01-01

    Activity-based probes (ABPs) are reactive small molecules that covalently bind to active enzymes. When tagged with a fluorophore, ABPs serve as powerful tools to investigate enzymatic activity across a wide variety of applications. In this article, we will provide detailed protocols for using fluorescent ABPs to biochemically characterize the activity of proteases in vitro. Furthermore, we will describe how these probes can be applied to image protease activity in live animals and tissues along with subsequent analysis by histology, flow cytometry, and SDS-PAGE. PMID:23788323

  17. Fluorescence Reporting Based on FRET Between Conjugated Polyelectrolyte and Organic Dye for Biosensor Applications

    Microsoft Academic Search

    Kan-Yi Pu; Bin Liu

    \\u000a \\u000a Abstract  Conjugated polyelectrolytes (CPEs), with highly delocalized electronic backbones and charged ionic side chains, are naturally\\u000a robust light-harvesting antenna for fluorescence resonance energy transfer (FRET) applications. This chapter describes FRET-based\\u000a biosensors using CPEs as energy donors from the viewpoint of sensing mechanism, donor–acceptor selection and detection targets.\\u000a Important information on how to design CPE structures and assay schemes is elucidated, and

  18. The Pocketscope: a spatial light modulator based epi-fluorescence microscope for optogenetics

    NASA Astrophysics Data System (ADS)

    Linnenberger, Anna; Peterka, Darcy S.; Quirin, Sean; Yuste, Rafael

    2014-09-01

    Microscopy incorporating spatial light modulators (SLMs) enables three dimensional (3D) excitation and monitoring of the activity of neuronal ensembles, enabling studies of neuronal circuit activity both in vitro and in vivo. In this paper we present a portable (22 cm x 42.5 cm x 30 cm), SLM-based epi-fluorescence upright microscope ("Pocketscope") that enables 3D calcium imaging and photoactivation of neurons in brain slices. Here we describe the implementation of the instrument; quantify the volume over which neural activity can be excited; and demonstrate the use of the system for mapping neural circuits in brain slices.

  19. Synthesis and spectroscopic study of highly fluorescent ?-enaminone based boron complexes

    NASA Astrophysics Data System (ADS)

    Kumbhar, Haribhau S.; Gadilohar, Balu L.; Shankarling, Ganapati S.

    2015-07-01

    The newly synthesized 1, 1, 2-trimethyl-1H benzo[e]indoline based ?-enaminone boron complexes exhibited the intense fluorescence (Fmax = 522-547 nm) in solution as well as in solid state (Fmax = 570-586 nm). These complexes exhibited large stoke shift, excellent thermal and photo stability when compared to the boron dipyrromethene (BODIPY) colorants. Optimized geometry and orbital distribution in ground states were computed by employing density functional theory (DFT). The cyclic voltammetry study revealed the better electron transport ability of these molecules than current electroluminescent materials like tris(8-hydroxyquinoli-nato)-aluminium (Alq3) and BODIPY, which can find application in electroluminescent devices.

  20. A cubic boron nitride film-based fluorescent sensor for detecting Hg2+

    NASA Astrophysics Data System (ADS)

    Liu, W. M.; Zhao, W. W.; Zhang, H. Y.; Wang, P. F.; Chong, Y. M.; Ye, Q.; Zou, Y. S.; Zhang, W. J.; Zapien, J. A.; Bello, I.; Lee, S. T.

    2009-05-01

    Cubic boron nitride (cBN) film-based sensors for detecting Hg2+ ions were developed by surface functionalization with dansyl chloride. To immobilize dansyl chloride, 3-aminopropyltriethoxy silane was modified on hydroxylated cBN surfaces to form an amino-group-terminated self-assembled monolayer. The covalent attachment of the amino groups was confirmed by x-ray photoelectron spectroscopy. The selectivity and sensitivity of the sensors to detect diverse metal cations in ethanol solutions were studied by using fluorescence spectroscopy, revealing a great selectivity to Hg2+ ions. Significantly, the dansyl-chloride-functionalized cBN film sensors were recyclable after the sensing test.

  1. Synchrotron based X-ray fluorescence activities at Indus-2: An overview

    SciTech Connect

    Tiwari, M. K., E-mail: mktiwari@rrcat.gov.in [Indus Synchrotrons Utilisation Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

    2014-04-24

    X-Ray fluorescence (XRF) spectrometry is a powerful non-destructive technique for elemental analysis of materials at bulk and trace concentration levels. Taking into consideration several advantages of the synchrotron based XRF technique and to fulfill the requirements of Indian universities users we have setup a microfocus XRF beamline (BL-16) on Indus-2 synchrotron light source. The beamline offers a wide range of usages – both from research laboratories and industries; and for researchers working in diverse fields. A brief overview of the measured performance of the beamline, design specifications including various attractive features and recent research activities carried out on the BL-16 beamline are presented.

  2. A LED-based method for monitoring NAD(P)H and FAD fluorescence in cell cultures and brain slices.

    PubMed

    Rösner, Jörg; Liotta, Agustin; Schmitz, Dietmar; Heinemann, Uwe; Kovács, Richard

    2013-01-30

    Nicotinamide- and flavine-adenine-dinucleotides (NAD(P)H and FADH?) are electron carriers involved in cellular energy metabolism and in a multitude of enzymatic processes. As reduced NAD(P)H and oxidised FAD molecules are fluorescent, changes in tissue auto-fluorescence provide valuable information on the cellular redox state and energy metabolism. Since fluorescence excitation, by mercury arc lamps (HBO) is inherently coupled to photo-bleaching and photo-toxicity, microfluorimetric monitoring of energy metabolism might benefit from the replacement of HBO lamps by light emitting diodes (LEDs). Here we describe a LED-based custom-built setup for monitoring NAD(P)H and FAD fluorescence at the level of single cells (HEK293) and of brain slices. We compared NAD(P)H bleaching characteristics with two light sources (HBO lamp and LED) as well as sensitivity and signal to noise ratio of three different detector types (multi-pixel photon counter (MPPC), photomultiplier tube (PMT) and photodiode). LED excitation resulted in reduced photo-bleaching at the same fluorescence output in comparison to excitation with the HBO lamp. Transiently increasing LED power resulted in reversible bleaching of NAD(P)H fluorescence. Recovery kinetics were dependent on metabolic substrates indicating coupling of NAD(P)H fluorescence to metabolism. Electrical stimulation of brain slices induced biphasic redox changes, as indicated by NAD(P)H/FAD fluorescence transients. Increasing the gain of PMT and decreasing the LED power resulted in similar sensitivity as obtained with the MPPC and the photodiode, without worsening the signal to noise ratio. In conclusion, replacement of HBO lamp with LED might improve conventional PMT based microfluorimetry of tissue auto-fluorescence. PMID:23142181

  3. High-throughput fluorescent-based NKCC functional assay in adherent epithelial cells

    PubMed Central

    2013-01-01

    Background The kidney-specific NKCC cotransporter isoform NKCC2 is involved in the Na+ reabsorption in the Thich Ascending Limb (TAL) cells and in the regulation of body fluid volume. In contrast, the isoform NKCC1 represents the major pathway for Cl- entry in endothelial cells, playing a crucial role in cell volume regulation and vascular tone. Importantly, both NKCC isoforms are involved in the regulation of blood pressure and represent important potential drug targets for the treatment of hypertension. Results Taking advantage of an existing Thallium (Tl+)-based kit, we set up a Tl+ influx-based fluorescent assay, that can accurately and rapidly measure NKCC transporter activity in adherent epithelial cells using the high-throughput Flex station device. We assessed the feasibility of this assay in the renal epithelial LLC-PK1 cells stably transfected with a previously characterized chimeric NKCC2 construct (c-NKCC2). We demonstrated that the assay is highly reproducible, offers high temporal resolution of NKCC-mediated ion flux profiles and, importantly, being a continuous assay, it offers improved sensitivity over previous endpoint NKCC functional assays. Conclusions So far the screening of NKCC transporters activity has been done by 86Rb+ influx assays. Indeed, a fluorescence-based high-throughput screening method for testing NKCC inhibitors would be extremely useful in the development and characterization of new anti-hypertensive drugs. PMID:23506056

  4. High performance magnesium anode in paper-based microfluidic battery, powering on-chip fluorescence assay.

    PubMed

    Koo, Youngmi; Sankar, Jagannathan; Yun, Yeoheung

    2014-09-01

    A high power density and long-lasting stable/disposable magnesium battery anode was explored for a paper-based fluidic battery to power on-chip functions of various Point of Care (POC) devices. The single galvanic cell with magnesium foil anode and silver foil cathode in Origami cellulose chip provided open circuit potential, 2.2?V, and power density, 3.0 mW/cm(2). A paper-based fluidic galvanic cell was operated with one drop of water (80 ?l) and continued to run until it was dry. To prove the concept about powering on-chip POC devices, two-serial galvanic cells are developed and incorporated with a UV-light emitting diode (??=?365?nm) and fluorescence assay for alkaline phosphatase reaction. Further, detection using smart phones was performed for quantitative measurement of fluorescent density. To conclude, a magnesium-based fluidic battery paper chip was extremely low-cost, required minute sample volumes, was easy to dispose of, light weight, easy to stack, store and transport, easy to fabricate, scalable, and has faster analysis times. PMID:25332741

  5. A novel fluorescence temperature sensor based on a surfactant-free PVA\\/borax\\/2-naphthol hydrogel network system

    Microsoft Academic Search

    Sang Min Lee; Woo Young Chung; Jong Kyu Kim; Dong Hack Suh

    2004-01-01

    This article is a report about the novel fluo- rescence temperature sensor based on a surfactant-free Poly (vinly alcohol)\\/borax\\/2-naphthol hydrogel system. The well-known fluorescence indicator, 2-naphthol, exhibits a change of fluorescence intensity when it is embedded in aqueous PVA\\/borax gel networks at various temperatures. The blue color emission intensity(PL:max 426 nm) of 2-naphthol in a basic hydrogel changed gradually to

  6. Stand-off tissue-based biosensors for the detection of chemical warfare agents using photosynthetic fluorescence induction

    Microsoft Academic Search

    Charlene A. Sanders; Miguel Rodriguez; Elias Greenbaum

    2001-01-01

    Tissue biosensors made from immobilized whole-cell photosynthetic microorganisms have been developed for the detection of airborne chemical warfare agents and simulants. The sensor read-out is based on well-known principles of fluorescence induction by living photosynthetic tissue. Like the cyanobacteria and algae from which they were constructed, the sensors are robust and mobile. The fluorescence signal from the sensors was stable

  7. A Simple System for Observing Dynamic Phase Equilibrium via an Inquiry-Based Laboratory or Demonstration

    ERIC Educational Resources Information Center

    Cloonan, Carrie A.; Andrew, Julie A.; Nichol, Carolyn A.; Hutchinson, John S.

    2011-01-01

    This article describes an activity that can be used as an inquiry-based laboratory or demonstration for either high school or undergraduate chemistry students to provide a basis for understanding both vapor pressure and the concept of dynamic phase equilibrium. The activity includes a simple setup to create a closed system of only water liquid and…

  8. New simple ESPI configurations for deformation studies on large structures based on diffused reference beam

    Microsoft Academic Search

    T. Santhanakrishnan; Nandigana Krishna Mohan; Rajpal S. Sirohi

    1996-01-01

    Two simple Electronic Speckle Pattern Interferometer (ESPI) configurations have been devised based on diffused reference beam which provides out-of-plane displacement data over the whole field. Both configurations use a tiny diffuser to generate the reference beam. This makes the system insensitive to reference beam misalignment, simplifies the construction of ESPI setup and allows larger area of observation unlike the conventional

  9. Efficient scrambling of wavelet-based compressed images: a comparison between simple techniques for mobile applications

    Microsoft Academic Search

    Giaime Ginesu; Tatiana Onali; Daniele D. Giusto

    2006-01-01

    Image scrambling is a fundamental task for several applications, from secure digital content transmission to mutual visual authentication. This paper proposes and evaluates several simple techniques with the aim of being efficient in respect to wavelet compression algorithms and fit for mobile applications. Then, the proposed methods are meant to comply with the average structure of wavelet-based coders and require

  10. A Simple Performance Analysis of Multiple Access RFID Networks Based on the Binary Tree Protocol

    Microsoft Academic Search

    F. Cappelletti; G. Ferrari; R. Raheli

    2006-01-01

    In this paper, we propose a simple performance analysis of radio frequency identification (RFID) networks , based on the binary tree medium access control (MAC) pro- tocol. We evaluate various network performance metrics, such as throughput, delay and average number of packets needed to take a census of the RFID tags. In order to validate our analytical results, we develop

  11. A simple approximation algorithm for WIS based on the approximability in k-partite graphs

    E-print Network

    Paris-Sud XI, Université de

    A simple approximation algorithm for WIS based on the approximability in k-partite graphs J show how an optimum weighted indepen- dent set in bipartite graphs and a -approximation of WIS in k Set; k-partite graphs. 1 Introduction In the Maximum Weighted Independent Set problem (WIS, for short

  12. An open source, web based, simple solution for seismic data dissemination and collaborative research

    Microsoft Academic Search

    Paolo Diviacco

    2005-01-01

    Collaborative research and data dissemination in the field of geophysical exploration need network tools that can access large amounts of data from anywhere using any PC or workstation. Simple solutions based on a combination of Open Source software can be developed to address such requests, exploiting the possibilities offered by the web technologies, and at the same time avoiding the

  13. Sprite: A Simple, Cheat-Proof, Credit-Based System for Mobile Ad-Hoc Networks

    Microsoft Academic Search

    Sheng Zhong; Jiang Chen; Yang Richard Yang

    2003-01-01

    Abstract— Mobile ad hoc networking has been an active research area for several years. How to stimulate cooperation among selfish mobile nodes, however, is not well addressed yet. In this paper, we propose Sprite, a simple, cheat-proof, credit- based system for stimulating cooperation among selfish nodes in mobile ad hoc networks. Our system provides incentive for mobile nodes to cooperate

  14. Sprite: A Simple, Cheat-Proof, Credit-Based System for Mobile Ad-Hoc Networks

    Microsoft Academic Search

    Sheng Zhong; Jiang Chen; Yang Richard Yang

    2002-01-01

    Mobile ad hoc networking has been an active research area for several years. How to stimulate cooperation among selfish mobile nodes, however, is not well addressed yet. In this paper, we propose Sprite, a simple, cheat-proof, credit- based system for stimulating cooperation among selfish nodes in mobile ad hoc networks. Our system provides incentive for mobile nodes to cooperate and

  15. Simple design method for shading devices and passive cooling strategies based on monthly average temperatures

    Microsoft Academic Search

    1983-01-01

    A simple method has been developed to approximate the need for shading and the potential of various passive cooling strategies based on readily available weather data. The method is quick and easy to use and is intended to be an aid in building schematic design. It uses daily maximum and minimum temperatures and mean coincident wet-bulb data for each month

  16. The subject is based upon the simple principles of electronics, but takes it to more exciting

    E-print Network

    Schnaufer, Achim

    The subject is based upon the simple principles of electronics, but takes it to more exciting renewable generation to converting supplies for use in consumer electronics. This is by no means an exhaustive list of the coverage of electronics and electrical engineering, and in today's world it is hard

  17. Design and implementation of a simple data query system based on PHP + TXT database

    Microsoft Academic Search

    Jia Gui-jun; Dong Yu-min; Cai Wen-yi

    2010-01-01

    Starting from practical application,this paper designs a simple data query system, which uses PHP + TXT database technology under Web server environment based on Unix system. The system can be applied to various types of data in WEB real-time online inquiry, and it has extensive application value.

  18. Wordnet creation and extension made simple: A multilingual lexicon-based approach using wiki resources

    E-print Network

    Paris-Sud XI, Université de

    Wordnet creation and extension made simple: A multilingual lexicon-based approach using wiki. Keywords: WordNet, Word Sense Disambiguation, Wiki resources 1. Introduction In recent years, researchers wordnets for a bunch of languages other than En- glish by using wiki resources: Navigli and Ponzetto (2010

  19. A Cognitively Based Simulation of Simple Organizations Ron Sun (rsun@rpi.edu)

    E-print Network

    Varela, Carlos

    A Cognitively Based Simulation of Simple Organizations Ron Sun (rsun@rpi.edu) Isaac Naveh (yizchaknaveh@yahoo.com) Cognitive Science Department Rensselaer Polytechnic Institute Troy, NY 12180, USA Abstract This paper explores cognitively realistic social simula- tions by deploying the CLARION cognitive

  20. A simple explanation for the space-based calculation of lava eruption rates

    E-print Network

    Wright, Robert

    A simple explanation for the space-based calculation of lava eruption rates Robert Wright a, Milton Keynes, UK Received 26 February 2001; accepted 5 July 2001 Abstract Knowing how lava effusion forecasts regarding how far lava will flow. However, problems exist in accurately determining effusion rates

  1. A Simple Stand Growth Model Based on Canopy Dynamics and Biomechanics

    E-print Network

    Cao, Quang V.

    A Simple Stand Growth Model Based on Canopy Dynamics and Biomechanics Thomas J. Dean, Mauricio be expressed in terms of wind drag. From this point of view, biomechanical principles determine the stem cross in a developing stand, biomechanics create a conceptual framework for predicting aboveground stem production

  2. Study of Rb atomic transitions D1,2 lines in strong magnetic field based on fluorescence spectra of sub -micron thin cell

    E-print Network

    Boyer, Edmond

    of a strong narrowing of the fluorescence spectrum of a nanocell with the atomic vapor column thickness L = 0Study of Rb atomic transitions D1,2 lines in strong magnetic field based on fluorescence spectra transitions. Particularly, with the help of fluorescence on 87 Rb, D2 line, Fg = 1 Fe = 3 transitions, three

  3. Coumarin-based 'turn-off' fluorescent chemosensor with high selectivity for Cu2+ in aqueous solution

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Jun; Qi, De-Qiang; You, Jin-Zong; Hu, Fei-Fei; Bian, Jia-Ying; Yang, Chun-Xia; Huang, Juan

    2015-07-01

    Coumarin-based "turn-off" fluorescent chemosensor, 3-acetoacetyl-7-diethylaminocoumarin (1), has been synthesized and structurally characterized by IR, 1H NMR and X-ray crystal structure analysis. The fluorescence behaviors in the presence of various metal ions were investigated in aqueous media. 1 Exhibits highly selective and sensitive absorbance and fluorescence sensing ability for Cu2+ over other metal ions. Addition of Cu2+ to the aqueous solution of 1 gave rise to obvious absorbance change and fluorescence quenching. Other competing ions, such as Mg2+, Ba2+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, Pb2+, Cd2+, Hg2+, induced negligible absorbance and fluorescence changes under the same conditions. The job's plot showed that the stoichiometry between 1 and Cu2+ was estimated to be 1:1. The fluorescence intensity varied almost linearly vs. the concentration of Cu2+ (1.0-7.0 ?M), and the detection limit of Cu2+ was estimated to be 1.81 nM, indicating that 1 can be used as "turn-off" fluorescent chemosensor to selectively detect Cu2+ in aqueous solution.

  4. Gold-nanorod-based colorimetric and fluorescent approach for sensitive and specific assay of disease-related gene and mutation.

    PubMed

    Wang, Wenhong; Zhao, Yina; Jin, Yan

    2013-11-27

    Sensitive and specific detection of disease-related gene and single nucleotide polymorphism (SNP) is of great importance in cancer diagnosis. Here, a colorimetric and fluorescent approach is described for detection of the p53 gene and SNP in homogeneous solution by using gold nanorods (GNRs) as both colorimetric probe and fluorescence quencher. Hairpin oligonucleotide was utilized as DNA probe to ensure highly sequence-specific detection of target DNA. In the presence of target DNA, the formation of DNA duplex greatly changed the electrostatic interaction between GNR and DNAs, leading to an obvious change in fluorescence and colorimetric response. The detection limit of fluorescent and colorimetric assay is 0.26 pM and 0.3 nM, respectively. Both fluorescence and colorimetric strategies were able to effectively discriminate complementary DNA from single-base mismatched DNA, which is meaningful for cancer diagnosis. More important, target DNA can be detected as low as 10 nM by the naked eye. Furthermore, transmission electron microscopy and fluorescence anisotropy measurements demonstrated that the color change as well as fluorescence quenching is ascribed to the DNA hybridization-induced aggregation of GNRs. Therefore, the assay provided a fast, sensitive, cost-effective, and specific sensing platform for detecting disease-related gene and SNP. PMID:24151993

  5. Multiplex competitive microbead-based flow cytometric immunoassay using quantum dot fluorescent labels.

    PubMed

    Yu, Hye-Weon; Kim, In S; Niessner, Reinhard; Knopp, Dietmar

    2012-10-31

    In answer to the ever-increasing need to perform the simultaneous analysis of environmental hazards, microcarrier-based multiplex technologies show great promise. Further integration with biofunctionalized quantum dots (QDs) creates new opportunities to extend the capabilities of multicolor flow cytometry with their unique fluorescence properties. Here, we have developed a competitive microbead-based flow cytometric immunoassay using QDs fluorescent labels for simultaneous detection of two analytes, bringing the benefits of sensitive, rapid and easy-of-manipulation analytical tool for environmental contaminants. As model target compounds, the cyanobacterial toxin microcystin-LR and the polycyclic aromatic hydrocarbon compound benzo[a]pyrene were selected. The assay was carried out in two steps: the competitive immunological reaction of multiple targets using their exclusive sensing elements of QD/antibody detection probes and antigen-coated microsphere, and the subsequent flow cytometric analysis. The fluorescence of the QD-encoded microsphere was thus found to be inversely proportional to target analyte concentration. Under optimized conditions, the proposed assay performed well within 30 min for the identification and quantitative analysis of the two environmental contaminants. For microcystin-LR and benzo[a]pyrene, dose-response curves with IC(50) values of 5 ?g L(-1) and 1.1 ?g L(-1) and dynamic ranges of 0.52-30 ?g L(-1) and 0.13-10 ?g L(-1) were obtained, respectively. Recovery was 92.6-106.5% for 5 types of water samples like bottled water, tap water, surface water and seawater using only filtration as sample pretreatment. PMID:23062440

  6. Fluorescent magnetic bead-based mast cell biosensor for electrochemical detection of allergens in foodstuffs.

    PubMed

    Jiang, Donglei; Zhu, Pei; Jiang, Hui; Ji, Jian; Sun, Xiulan; Gu, Wenshu; Zhang, Genyi

    2015-08-15

    In this study, a novel electrochemical rat basophilic leukemia cell (RBL-2H3) cell sensor, based on fluorescent magnetic beads, has been developed for the detection and evaluation of different allergens in foodstuffs. Fluorescein isothiocyanate (FITC) was successfully fused inside the SiO2 layer of SiO2 shell-coated Fe3O4 nanoparticles, which was superior to the traditional Fe3O4@SiO2@FITC modification process. The as-synthesized fluorescent magnetic beads were then encapsulated with lipidosome to form cationic magnetic fluorescent nanoparticles (CMFNPs) for mast cell magnetofection. The CMFNPs were then characterized by SEM, TEM, VSM, FTIR, and XRD analyses, and transfected into RBL-2H3 cells through a highly efficient, lipid-mediated magnetofection procedure. Magnetic glassy carbon electrode (MGCE), which possesses excellent reproducibility and regeneration qualities, was then employed to adsorb the CMFNP-transfected RBL-2H3 cells activated by an allergen antigen for electrochemical assay. Results show that the exposure of model antigen-dinitrophenol-bovine serum albumin (DNP-BSA) to anti-DNP IgE-sensitized mast cells induced a robust and long-lasting electrochemical impedance signal in a dose-dependent manner. The detection limit was identified at 3.3×10(-4)ng/mL. To demonstrate the utility of this mast cell-based biosensor for detection of real allergens in foodstuffs, Anti-Pen a1 IgE and Anti-PV IgE-activated cells were employed to quantify both shrimp allergen tropomyosin (Pen a 1) and fish allergen parvalbumin (PV). Results show high detection accuracy for these targets, with a limit of 0.03?g/mL (shrimp Pen a 1) and 0.16ng/mL (fish PV), respectively. To this effect, we conclude the proposed method is a facile, highly sensitive, innovative electrochemical method for the evaluation of food allergens. PMID:25889258

  7. Detection of acrylamide in potato chips using a fluorescent sensing method based on acrylamide polymerization-induced distance increase between quantum dots.

    PubMed

    Hu, Qinqin; Xu, Xiahong; Li, Zhanming; Zhang, Ying; Wang, Jianping; Fu, Yingchun; Li, Yanbin

    2014-04-15

    Acrylamide is a neurotoxin and potential carcinogen, but is found in various thermally processed foods such as potato chips, biscuits, and coffee. Simple and sensitive methods for on-line detection of acrylamide are needed to ensure food safety. In this paper, a novel fluorescent sensing method based on acrylamide polymerization-induced distance increase between quantum dots (QDs) was proposed for detecting acrylamide in potato chips. The functional QDs were prepared by their binding with N-acryloxysuccinimide (NAS), which was characterized by Fourier transform infrared (FR-IR) spectra. The carbon-carbon double bonds of NAS modified QDs polymerized with assistance of photo initiator under UV irradiation, leading to QDs getting closer along with fluorescence intensity decreasing. Acrylamide in the sample participated in the polymerization and induced an increase of fluorescence intensity. This method possessed a linear range from 3.5×10(-5) to 3.5 g L(-1) (r(2)=0.94) and a limit of detection of 3.5×10(-5) g L(-1). Although the sensitivity and specificity cannot be compared with standard LC-MS/MS analysis, this new method requires much less time and cost, which is promising for on-line rapid detection of acrylamide in food processing. PMID:24252761

  8. Fluorescence-Based Methods for Detecting Caries Lesions: Systematic Review, Meta-Analysis and Sources of Heterogeneity

    PubMed Central

    Gimenez, Thais; Braga, Mariana Minatel; Raggio, Daniela Procida; Deery, Chris; Ricketts, David N.; Mendes, Fausto Medeiros

    2013-01-01

    Background Fluorescence-based methods have been proposed to aid caries lesion detection. Summarizing and analysing findings of studies about fluorescence-based methods could clarify their real benefits. Objective We aimed to perform a comprehensive systematic review and meta-analysis to evaluate the accuracy of fluorescence-based methods in detecting caries lesions. Data Source Two independent reviewers searched PubMed, Embase and Scopus through June 2012 to identify papers/articles published. Other sources were checked to identify non-published literature. Study Eligibility Criteria, Participants and Diagnostic Methods The eligibility criteria were studies that: (1) have assessed the accuracy of fluorescence-based methods of detecting caries lesions on occlusal, approximal or smooth surfaces, in both primary or permanent human teeth, in the laboratory or clinical setting; (2) have used a reference standard; and (3) have reported sufficient data relating to the sample size and the accuracy of methods. Study Appraisal and Synthesis Methods A diagnostic 2×2 table was extracted from included studies to calculate the pooled sensitivity, specificity and overall accuracy parameters (Diagnostic Odds Ratio and Summary Receiver-Operating curve). The analyses were performed separately for each method and different characteristics of the studies. The quality of the studies and heterogeneity were also evaluated. Results Seventy five studies met the inclusion criteria from the 434 articles initially identified. The search of the grey or non-published literature did not identify any further studies. In general, the analysis demonstrated that the fluorescence-based method tend to have similar accuracy for all types of teeth, dental surfaces or settings. There was a trend of better performance of fluorescence methods in detecting more advanced caries lesions. We also observed moderate to high heterogeneity and evidenced publication bias. Conclusions Fluorescence-based devices have similar overall performance; however, better accuracy in detecting more advanced caries lesions has been observed. PMID:23593215

  9. A novel device based on a fluorescent cross-responsive sensor array for detecting lung cancer related volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Lei, Jin-can; Hou, Chang-jun; Huo, Dan-qun; Luo, Xiao-gang; Bao, Ming-ze; Li, Xian; Yang, Mei; Fa, Huan-bao

    2015-02-01

    In this paper, a novel, simple, rapid, and low-cost detection device for lung cancer related Volatile Organic Compounds (VOCs) was constructed. For this task, a sensor array based on cross-responsive mechanism was designed. A special gas chamber was made to insure sensor array exposed to VOCs sufficiently and evenly, and FLUENT software was used to simulate the performance of the gas chamber. The data collection and processing system was used to detect fluorescent changes of the sensor arrays before and after reaction, and to extract unique patterns of the tested VOCs. Four selected VOCs, p-xylene, styrene, isoprene, and hexanal, were detected by the proposed device. Unsupervised pattern recognition methods, hierarchical cluster analysis and principal component analysis, were used to analyze data. The results showed that the methods could 100% discriminate the four VOCs. What is more, combined with artificial neural network, the correct rate of quantitative detection was up to 100%, and the device obtained responses at concentrations below 50 ppb. In conclusion, the proposed detection device showed excellent selectivity and discrimination ability for the VOCs related to lung cancer. Furthermore, our preliminary study demonstrated that the proposed detection device has brilliant potential application for early clinical diagnosis of lung cancer.

  10. In Vivo Stable Tumor-Specific Painting in Various Colors Using Dehalogenase-Based Protein-Tag Fluorescent Ligands

    PubMed Central

    Kosaka, Nobuyuki; Ogawa, Mikako; Choyke, Peter L.; Karassina, Natasha; Corona, Cesear; McDougall, Mark; Lynch, David; Hoyt, Clifford; Levenson, Richard; Los, Georgyi V.; Kobayashi, Hisataka

    2010-01-01

    In vivo fluorescence cancer imaging is an important tool in understanding tumor growth and therapeutic monitoring and can be performed either with endogenously produced fluorescent proteins or exogenously introduced fluorescent probes bound to targeting molecules. However, endogenous fluorescence proteins cannot be altered after transfection, thus requiring rederivation of cell lines for each desired color, while exogenously targeted fluorescence probes are limited by the heterogeneous expression of naturally occurring cellular targets. In this study, we adapted the dehalogenase-based protein-Tag (HaloTag) system to in vivo cancer imaging. By introducing highly expressed HaloTag receptors (HaloTagR) in cancer cells coupled with an externally injected a range of fluorophore-conjugated dehalogenase-reactive sequences. Tumor nodules arising from a single transfected cell line were stably labeled with fluorescence varying in emission spectra from green to near infrared. After establishing and validating a SHIN3 cell line stably transfected with HaloTagR (HaloTagR-SHIN3), in vivo spectral fluorescence imaging studies were performed in live animals using a peritoneal dissemination model. The tumor nodules arising from HaloTagR-SHIN3 could be successfully labeled by 4 different fluorophore-conjugated HaloTag-ligands each emitting light at different wavelengths. These fluorophores could be alternated on serial imaging sessions permitting assessment of interval growth. Fluorescence was retained in histological specimens after fixation. Thus, this tagging system proves versatile both for in vivo and in vitro imaging without requiring modification of the underlying cell line. Thus, this strategy can overcome some of the limitations associated with the use of endogenous fluorescent proteins and exogenous targeted optical agents in current use. PMID:19514716

  11. Light-emitting diode and laser fluorescence-based devices in detecting occlusal caries

    NASA Astrophysics Data System (ADS)

    Rodrigues, Jonas A.; Hug, Isabel; Neuhaus, Klaus W.; Lussi, Adrian

    2011-10-01

    The aim of this study was to assess the performance of two light-emitting diode (LED)- and two laser fluorescence-based devices in detecting occlusal caries in vitro. Ninety-seven permanent molars were assessed twice by two examiners using two LED- (Midwest Caries - MID and VistaProof - VP) and two laser fluorescence-based (DIAGNOdent 2095 - LF and DIAGNOdent pen 2190 - LFpen) devices. After measuring, the teeth were histologically prepared and classified according to lesion extension. At D1 the specificities were 0.76 (LF and LFpen), 0.94 (MID), and 0.70 (VP); the sensitivities were 0.70 (LF), 0.62 (LFpen), 0.31 (MID), and 0.75 (VP). At D3 threshold the specificities were 0.88 (LF), 0.87 (LFpen), 0.90 (MID), and 0.70 (VP); the sensitivities were 0.63 (LF and LFpen), 0.70 (MID), and 0.96 (VP). Spearman's rank correlations with histology were 0.56 (LF), 0.51 (LFpen), 0.55 (MID), and 0.58 (VP). Inter- and intraexaminer ICC values were high and varied from 0.83 to 0.90. Both LF devices seemed to be useful auxiliary tools to the conventional methods, presenting good reproducibility and better accuracy at D3 threshold. MID was not able to differentiate sound surfaces from enamel caries and VP still needs improvement on the cut-off limits for its use.

  12. A new fundamental parameter based calibration procedure for micro X-ray fluorescence spectrometers

    NASA Astrophysics Data System (ADS)

    Wolff, Timo; Malzer, Wolfgang; Mantouvalou, Ioanna; Hahn, Oliver; Kanngießer, Birgit

    2011-02-01

    Fundamental parameter based quantification of X-ray fluorescence (XRF) measurement data requires an accurate knowledge of the spectrometer parameters, including the spectral distribution of the excitation radiation. In case of micro-XRF where a polycapillary optic is utilized in the excitation channel this distribution is changed due to the transmission properties of the lens. A new calibration procedure, based on fluorescence data of thin standard samples, was developed to determine the excitation spectrum, i.e., the product of the X-ray tube spectrum and the transmission of the used X-ray optic of a micro-XRF setup. The calibration result was validated by the quantitative analyses of certified multi-element reference standards and shows uncertainties in the order of 2% for main components, 10% for minor elements and 25% for trace elements. The influence of secondary order effects like Coster-Kronig transitions and cascade effects is analyzed and the accuracy of fundamental parameters in common databases is discussed.

  13. Pico-projector-based optical sectioning microscopy for 3D chlorophyll fluorescence imaging of mesophyll cells

    NASA Astrophysics Data System (ADS)

    Chen, Szu-Yu; Hsu, Yu John; Yeh, Chia-Hua; Chen, S.-Wei; Chung, Chien-Han

    2015-03-01

    A pico-projector-based optical sectioning microscope (POSM) was constructed using a pico-projector to generate structured illumination patterns. A net rate of 5.8 × 106 pixel/s and sub-micron spatial resolution in three-dimensions (3D) were achieved. Based on the pico-projector’s flexibility in pattern generation, the characteristics of POSM with different modulation periods and at different imaging depths were measured and discussed. With the application of different modulation periods, 3D chlorophyll fluorescence imaging of mesophyll cells was carried out in freshly plucked leaves of four species without sectioning or staining. For each leaf, an average penetration depth of 120 ?m was achieved. Increasing the modulation period along with the increment of imaging depth, optical sectioning images can be obtained with a compromise between the axial resolution and signal-to-noise ratio. After ?30 min imaging on the same area, photodamage was hardly observed. Taking the advantages of high speed and low damages of POSM, the investigation of the dynamic fluorescence responses to temperature changes was performed under three different treatment temperatures. The three embedded blue, green and red light-emitting diode light sources were applied to observe the responses of the leaves with different wavelength excitation.

  14. Characterizing natural colloidal/particulate-protein interactions using fluorescence-based techniques and principal component analysis.

    PubMed

    Peiris, Ramila H; Ignagni, Nicholas; Budman, Hector; Moresoli, Christine; Legge, Raymond L

    2012-09-15

    Characterization of the interactions between natural colloidal/particulate- and protein-like matter is important for understanding their contribution to different physiochemical phenomena like membrane fouling, adsorption of bacteria onto surfaces and various applications of nanoparticles in nanomedicine and nanotoxicology. Precise interpretation of the extent of such interactions is however hindered due to the limitations of most characterization methods to allow rapid, sensitive and accurate measurements. Here we report on a fluorescence-based excitation-emission matrix (EEM) approach in combination with principal component analysis (PCA) to extract information related to the interaction between natural colloidal/particulate- and protein-like matter. Surface plasmon resonance (SPR) analysis and fiber-optic probe based surface fluorescence measurements were used to confirm that the proposed approach can be used to characterize colloidal/particulate-protein interactions at the physical level. This method has potential to be a fundamental measurement of these interactions with the advantage that it can be performed rapidly and with high sensitivity. PMID:22967579

  15. Light-emitting diode and laser fluorescence-based devices in detecting occlusal caries.

    PubMed

    Rodrigues, Jonas A; Hug, Isabel; Neuhaus, Klaus W; Lussi, Adrian

    2011-10-01

    The aim of this study was to assess the performance of two light-emitting diode (LED)- and two laser fluorescence-based devices in detecting occlusal caries in vitro. Ninety-seven permanent molars were assessed twice by two examiners using two LED- (Midwest Caries - MID and VistaProof - VP) and two laser fluorescence-based (DIAGNOdent 2095 - LF and DIAGNOdent pen 2190 - LFpen) devices. After measuring, the teeth were histologically prepared and classified according to lesion extension. At D1 the specificities were 0.76 (LF and LFpen), 0.94 (MID), and 0.70 (VP); the sensitivities were 0.70 (LF), 0.62 (LFpen), 0.31 (MID), and 0.75 (VP). At D(3) threshold the specificities were 0.88 (LF), 0.87 (LFpen), 0.90 (MID), and 0.70 (VP); the sensitivities were 0.63 (LF and LFpen), 0.70 (MID), and 0.96 (VP). Spearman's rank correlations with histology were 0.56 (LF), 0.51 (LFpen), 0.55 (MID), and 0.58 (VP). Inter- and intraexaminer ICC values were high and varied from 0.83 to 0.90. Both LF devices seemed to be useful auxiliary tools to the conventional methods, presenting good reproducibility and better accuracy at D(3) threshold. MID was not able to differentiate sound surfaces from enamel caries and VP still needs improvement on the cut-off limits for its use. PMID:22029365

  16. Identification of olive pollen allergens using a fluorescence-based 2D multiplex method.

    PubMed

    Zienkiewicz, Krzysztof; Alché, Juan de Dios; Zienkiewicz, Agnieszka; Tormo, Alejandro; Castro, Antonio Jesús

    2015-04-01

    Olive (Olea europaea L.) pollen is a major health concern in the Mediterranean countries and some olive growing regions in America and Australia. The molecular variability of pollen allergens constitutes a handicap for commercial extract standardization, which is the base of current diagnosis and vaccination procedures. In this paper, we report a time-saving and plant material saving multiplex detection method for the rapid and simultaneous analysis of Ole e 1, Ole e 2, and Ole e 5 allergen polymorphism on a single blot. This method combines high-resolution 2DE techniques with high-sensitive fluorescence-based detection methods. Using this strategy, we were capable to identify a higher number of allergen forms compared with classical 1D approach. The use of fluorescent probes and the increased resolution of 2D blots avoided overlapping effects, and allow estimating the amount of individual allergen forms. In addition, the pattern and identity of the IgE-reactive proteins of either a population or individual patients allergic to olive pollen was also effortlessly determined in a single additional step. This flexible method might be extended to a higher number of olive allergens and cultivars, and is also applicable to other allergogenic plant species and sources. PMID:25640071

  17. Effect of Clouds on Apertures of Space-based Air Fluorescence Detectors

    NASA Technical Reports Server (NTRS)

    Sokolsky, P.; Krizmanic, J.

    2003-01-01

    Space-based ultra-high-energy cosmic ray detectors observe fluorescence light from extensive air showers produced by these particles in the troposphere. Clouds can scatter and absorb this light and produce systematic errors in energy determination and spectrum normalization. We study the possibility of using IR remote sensing data from MODIS and GOES satellites to delimit clear areas of the atmosphere. The efficiency for detecting ultra-high-energy cosmic rays whose showers do not intersect clouds is determined for real, night-time cloud scenes. We use the MODIS SST cloud mask product to define clear pixels for cloud scenes along the equator and use the OWL Monte Carlo to generate showers in the cloud scenes. We find the efficiency for cloud-free showers with closest approach of three pixels to a cloudy pixel is 6.5% exclusive of other factors. We conclude that defining a totally cloud-free aperture reduces the sensitivity of space-based fluorescence detectors to unacceptably small levels.

  18. Determination of trace aluminum by fluorescence quenching method based on catalysis of potassium chlorate oxidizing alizarin red.

    PubMed

    Shao-Qin, Lin; Xuan, Lin; Shi-Rong, Hu; Li-Qing, Zeng; Yan, Wang; Li, Chen; Jia-Ming, Liu; Long-Di, Li

    2005-11-01

    A new method for the determination of trace aluminum has been proposed. It is based on the fact that alizarin red can emit strong and stable fluorescence at 80 degrees C for 30 min and Al(3+) can effectively catalyze potassium chlorate oxidizing alizarin red to form non-fluorescence complex which cause the fluorescence quenching. The linear dynamic range of this method is 0.040-4.00 ngl(-1) with a detection limit of 5.3 pgl(-1). The regression equation can be expressed as DeltaI(f)=8.731+21.73c(Al(3+)) (ngl(-1)), with the correlation coefficient r=0.9992 (n=6). This sensitive, rapid and accurate method has been applied to the determination of trace aluminum(III) in human hair and tea samples successfully. What is more, the mechanism of catalyzing potassium chlorate oxidizing alizarin red by the fluorescence quenching method is also discussed. PMID:16257769

  19. Determination of trace aluminum by fluorescence quenching method based on catalysis of potassium chlorate oxidizing alizarin red

    NASA Astrophysics Data System (ADS)

    Shao-Qin, Lin; Xuan, Lin; Shi-Rong, Hu; Li-Qing, Zeng; Yan, Wang; Li, Chen; Jia-Ming, Liu; Long-Di, Li

    2005-11-01

    A new method for the determination of trace aluminum has been proposed. It is based on the fact that alizarin red can emit strong and stable fluorescence at 80 °C for 30 min and Al 3+ can effectively catalyze potassium chlorate oxidizing alizarin red to form non-fluorescence complex which cause the fluorescence quenching. The linear dynamic range of this method is 0.040-4.00 ng l -1 with a detection limit of 5.3 pg l -1. The regression equation can be expressed as ? If = 8.731 + 21.73 c (ng l -1), with the correlation coefficient r = 0.9992 ( n = 6). This sensitive, rapid and accurate method has been applied to the determination of trace aluminum(III) in human hair and tea samples successfully. What is more, the mechanism of catalyzing potassium chlorate oxidizing alizarin red by the fluorescence quenching method is also discussed.

  20. Microtubule Affinity Regulating Kinase Activity in Living Neurons Was Examined by a Genetically Encoded Fluorescence Resonance Energy Transfer/Fluorescence Lifetime Imaging-based Biosensor

    PubMed Central

    Timm, Thomas; von Kries, Jens Peter; Li, Xiaoyu; Zempel, Hans; Mandelkow, Eckhard; Mandelkow, Eva-Maria

    2011-01-01

    Protein kinases of the microtubule affinity regulating kinase (MARK)/Par-1 family play important roles in the establishment of cellular polarity, cell cycle control, and intracellular signal transduction. Disturbance of their function is linked to cancer and brain diseases, e.g. lissencephaly and Alzheimer disease. To understand the biological role of MARK family kinases, we searched for specific inhibitors and a biosensor for MARK activity. A screen of the ChemBioNet library containing ?18,000 substances yielded several compounds with inhibitory activity in the low micromolar range and capable of inhibiting MARK activity in cultured cells and primary neurons, as judged by MARK-dependent phosphorylation of microtubule-associated proteins and its consequences for microtubule integrity. Four of the compounds share a 9-oxo-9H-acridin-10-yl structure as a basis that will serve as a lead for optimization of inhibition efficiency. To test these inhibitors, we developed a cellular biosensor for MARK activity based on a MARK target sequence attached to the 14-3-3 scaffold protein and linked to enhanced cyan or teal and yellow fluorescent protein as FRET donor and acceptor pairs. Transfection of the teal/yellow fluorescent protein sensor into neurons and imaging by fluorescence lifetime imaging revealed that MARK was particularly active in the axons and growth cones of differentiating neurons. PMID:21984823

  1. DNA separation and fluorescent detection in an optofluidic chip with sub-base-pair resolution

    NASA Astrophysics Data System (ADS)

    Pollnau, Markus; Hammer, Manfred; Dongre, Chaitanya; Hoekstra, Hugo J.

    2015-03-01

    DNA sequencing in a lab-on-a-chip aims at providing cheap, high-speed analysis of low reagent volumes to, e.g., identify genomic deletions or insertions associated with genetic illnesses. Detecting single base-pair insertions/deletions from DNA fragments in the diagnostically relevant range of 150-1000 base-pairs requires a sizing accuracy of S < 10-3. Here we demonstrate S = 4×10-4. A microfluidic chip was post-processed by femtosecond-laser writing of an optical waveguide. 12 blue-labeled and 23 red-labeled DNA fragments were separated in size by capillary electrophoresis, each set excited by either of two lasers power-modulated at different frequencies, their fluorescence detected by a photomultiplier, and blue/red signals distinguished by Fourier analysis. Different calibration strategies were tested: a) use either set of DNA molecules as reference to calibrate the set-up and identify the base-pair sizes of the other set in the same flow experiment, thereby eliminating variations in temperature, wall-coating and sieving-gel conditions, and actuation voltages; b) use the same molecular set as reference and sample with the same fluorescence label, flown in consecutive experiments; c) perform cross-experiments based on different molecular sets with different labels, flown in consecutive experiments. From the results we conclude: Applying quadratic instead of linear fit functions improves the calibration accuracy. Blue-labeled molecules are separated with higher accuracy. The influence of dye label is higher than fluctuations between two experiments. Choosing a single, suitable dye label combined with reference calibration and sample investigation in consecutive experiments results in S = 4×10-4, enabling detection of single base-pair insertion/deletion in a lab-on-a-chip.

  2. In vitro detection of drug-induced phospholipidosis using gene expression and fluorescent phospholipid based methodologies.

    PubMed

    Nioi, Paul; Perry, Brad K; Wang, Er-Jia; Gu, Yi-Zhong; Snyder, Ronald D

    2007-09-01

    Phospholipidosis (PLD) is characterized by the excessive intracellular accumulation of phospholipids. It is well established that a large number of cationic amphiphilic drugs have the potential to induce PLD. In the present study, we describe two facile in vitro methods to determine the PLD-inducing potential of a molecule. The first approach is based on a recent study by (Sawada et al., 2005, Toxicol. Sci. 83, 282-292) in which 17 genes were identified as potential biomarkers of PLD in HepG2 cells. To confirm the utility of this gene panel, we treated HepG2 cells with PLD-positive and -negative compounds and then analyzed gene expression using real-time PCR. Our initial analysis, which used a single dose of each drug, correctly identified five of eight positive compounds and four of four negative compounds. We then increased the doses of the three false negatives (amiodarone, tamoxifen, and loratadine) and found that the changes in gene expression became large enough to correctly identify them as PLD-inducing drugs. Our results suggest that a range of concentrations should be used to increase the accuracy of prediction in this assay. Our second approach utilized a fluorescently labeled phospholipid (LipidTox) which was added to the media of growing HepG2 cells along with compounds positive and negative for PLD. Phospholipid accumulation was determined using confocal microscopy and, more quantitatively, using a 96-well plate assay and a fluorescent plate reader. Using an expanded set of compounds, we show that this assay correctly identified 100% of PLD-positive and -negative compounds. Dose-dependent increases in intracellular fluorescent phospholipid accumulation were observed. We found that this assay was less time consuming, more sensitive, and higher throughput than gene expression analysis. To our knowledge, this study represents the first validation of the use of LipidTox in identifying drugs that can induce PLD. PMID:17567588

  3. A Red Cy3-Based Biarsenical Fluorescent Probe Targeted to a Complementary Binding Peptide

    SciTech Connect

    Cao, Haishi; Xiong, Yijia; Wang, Ting; Chen, Baowei; Squier, Thomas C.; Mayer, M. Uljana

    2007-06-22

    Small-molecule biarsenical multiuse affinity probes (MAPs) FlAsH and ReAsH,1,2 in conjunction with complementary protein tags, are important new tools for analyzing cellular function through live-cell imaging,3,4 targeted protein inactivation,5 and the measurement of protein dynamics and binding.6 In addition, MAPs serve as affinity reagents for isolating intact protein complexes for complementary structural measurements.7 These first-generation MAPs bind to a tetracoordinate arsenic group (TAG) binding motif (i.e., CCXXCC or FlAsHTAG) genetically engineered onto a protein of interest. They are superior to other targeted labeling strategies (such as the Halo-tag, the SNAP tag, and fluorescent proteins) in that the small peptide tag does not disrupt protein protein interactions nor perturb the correct trafficking of tagged proteins.8,9 The conserved interatomic distance (*6 Å) between the two arsenic moieties in FlAsH and ReAsH complicates the selective labeling of multiple proteins with different reporters. To overcome these limitations, we have synthesized a new biarsenical MAP (i.e., AsCy3) based on Cy3, a member of the cyanine dye family, whose well-recognized brightness and photostability facilitate their utility in single-molecule measurements. The large interatomic distance between the two arsenics in AsCy3 (*14.5 Å) coupled with the identification of a complementary high-affinity binding sequence CCKAEAACC (Cy3TAG) permits the simultaneous application of both AsCy3 and FlAsH to selectively label their respective binding TAGs in different proteins. In addition, the fluorescence of FlAsH overlaps with the absorption of AsCy3, which can act as an acceptor of fluorescence resonance energy transfer (FRET) to allow ratiometric measurements of protein association.

  4. BODIPY-based azamacrocyclic ensemble for selective fluorescence detection and quantification of homocysteine in biological applications.

    PubMed

    Li, Zan; Geng, Zhi-Rong; Zhang, Cui; Wang, Xiao-Bo; Wang, Zhi-Lin

    2015-10-15

    Considering the significant role of plasma homocysteine in physiological processes, two ensembles (F465-Cu(2+) and F508-Cu(2+)) were constructed based on a BODIPY (4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene) scaffold conjugated with an azamacrocyclic (1,4,7-triazacyclononane and 1,4,7,10-tetraazacyclododecane) Cu(2+) complex. The results of this effort demonstrated that the F465-Cu(2+) ensemble could be employed to detect homocysteine in the presence of other biologically relevant species, including cysteine and glutathione, under physiological conditions with high selectivity and sensitivity in the turn-on fluorescence mode, while the F508-Cu(2+) ensemble showed no fluorescence responses toward biothiols. A possible mechanism for this homocysteine-specific specificity involving the formation of a homocysteine-induced six-membered ring sandwich structure was proposed and confirmed for the first time by time-dependent fluorescence spectra, ESI-MS and EPR. The detection limit of homocysteine in deproteinized human serum was calculated to be 241.4nM with a linear range of 0-90.0?M and the detection limit of F465 for Cu(2+) is 74.7nM with a linear range of 0-6.0?M (F508, 80.2nM, 0-7.0?M). We have demonstrated the application of the F465-Cu(2+) ensemble for detecting homocysteine in human serum and monitoring the activity of cystathionine ?-synthase in vitro. PMID:25951084

  5. Ion track reconstruction in 3D using alumina-based fluorescent nuclear track detectors.

    PubMed

    Niklas, M; Bartz, J A; Akselrod, M S; Abollahi, A; Jäkel, O; Greilich, S

    2013-09-21

    Fluorescent nuclear track detectors (FNTDs) based on Al2O3: C, Mg single crystal combined with confocal microscopy provide 3D information on ion tracks with a resolution only limited by light diffraction. FNTDs are also ideal substrates to be coated with cells to engineer cell-fluorescent ion track hybrid detectors (Cell-Fit-HD). This radiobiological tool enables a novel platform linking cell responses to physical dose deposition on a sub-cellular level in proton and heavy ion therapies. To achieve spatial correlation between single ion hits in the cell coating and its biological response the ion traversals have to be reconstructed in 3D using the depth information gained by the FNTD read-out. FNTDs were coated with a confluent human lung adenocarcinoma epithelial (A549) cell layer. Carbon ion irradiation of the hybrid detector was performed perpendicular and angular to the detector surface. In situ imaging of the fluorescently labeled cell layer and the FNTD was performed in a sequential read-out. Making use of the trajectory information provided by the FNTD the accuracy of 3D track reconstruction of single particles traversing the hybrid detector was studied. The accuracy is strongly influenced by the irradiation angle and therefore by complexity of the FNTD signal. Perpendicular irradiation results in highest accuracy with error of smaller than 0.10°. The ability of FNTD technology to provide accurate 3D ion track reconstruction makes it a powerful tool for radiobiological investigations in clinical ion beams, either being used as a substrate to be coated with living tissue or being implanted in vivo. PMID:23965401

  6. The Application of Fluorescence Techniques for Mudlogging Analysis of Oil Drilled With Oil-Based Muds

    Microsoft Academic Search

    M. V. Reyes

    1994-01-01

    The Texaco E and P Technology Div. has developed two fluorescence techniques to enhance the detection of crude oil extracted from formation samples and to improve mud logging as a formation evaluation tool. The quantitative fluorescence technique (QFT) is a portable field method that uses a single excitation wavelength and measures fluorescence at a narrow emission range. When plotted vs.

  7. Hardware implementation and calibration of background noise for an integration-based fluorescence lifetime sensing algorithm.

    PubMed

    Li, Day-Uei; Walker, Richard; Richardson, Justin; Rae, Bruce; Buts, Alex; Renshaw, David; Henderson, Robert

    2009-04-01

    A new integration based fluorescence lifetime imaging microscopy (FLIM) called IEM has been proposed to implement lifetime extraction [J. Opt. Soc. Am. A25, 1190 (2008)]. A real-time hardware implementation of the IEM FLIM algorithm suitable for single photon avalanche diode arrays in nanometer-scale CMOS technology is now proposed. The problems of reduced pixel readout bandwidth and background noise are studied and a calibration method suitable for FPGA implementation is introduced. In particular, the relationship between signal-to-noise ratio and background noise is considered based on statistics theory and compared with a rapid lifetime determination method and maximum-likelihood estimator with-without background correction. The results are also compared with Monte Carlo simulations giving good agreement. The performance of the proposed methods has been tested on monoexponential decay experimental data. The high flexibility, wide range, and hardware friendliness make IEM the best candidate for system-on-chip integration to our knowledge. PMID:19340255

  8. Total internal reflection-based module for fluorescence and absorbance detection

    NASA Astrophysics Data System (ADS)

    Verschooten, Tom; Ottevaere, Heidi; Vervaeke, Michael; Van Erps, Jürgen; Thienpont, Hugo

    2014-07-01

    We present a miniaturized polymer-based micro-optical detection unit for ultraviolet and visible laser-induced fluorescence (LIF) and absorbance (ABS) analysis with an interaction length of 3 mm. We use nonsequential optical ray tracing simulations to model the system and to optimize its performance with respect to optical efficiency and system complexity. The design features a compact optical system combining total internal reflection (TIR) mirrors and refractive optics. The detection module is prototyped with deep proton writing in 2-mm-thick polymethylmethacrylate and quantitatively characterized using a three-dimensional coordinate measurement machine. We demonstrate the proof-of-concept of this TIR mirror-based module for coumarin 480 obtaining limits of detection of 50 pM and 500 nM for LIF and ABS, respectively.

  9. Total variation versus wavelet-based methods for image denoising in fluorescence lifetime imaging microscopy.

    PubMed

    Chang, Ching-Wei; Mycek, Mary-Ann

    2012-05-01

    We report the first application of wavelet-based denoising (noise removal) methods to time-domain box-car fluorescence lifetime imaging microscopy (FLIM) images and compare the results to novel total variation (TV) denoising methods. Methods were tested first on artificial images and then applied to low-light live-cell images. Relative to undenoised images, TV methods could improve lifetime precision up to 10-fold in artificial images, while preserving the overall accuracy of lifetime and amplitude values of a single-exponential decay model and improving local lifetime fitting in live-cell images. Wavelet-based methods were at least 4-fold faster than TV methods, but could introduce significant inaccuracies in recovered lifetime values. The denoising methods discussed can potentially enhance a variety of FLIM applications, including live-cell, in vivo animal, or endoscopic imaging studies, especially under challenging imaging conditions such as low-light or fast video-rate imaging. PMID:22415891

  10. Review of Fluorescence-Based Velocimetry Techniques to Study High-Speed Compressible Flows

    NASA Technical Reports Server (NTRS)

    Bathel, Brett F.; Johansen, Criag; Inman, Jennifer A.; Jones, Stephen B.; Danehy, Paul M.

    2013-01-01

    This paper reviews five laser-induced fluorescence-based velocimetry techniques that have been used to study high-speed compressible flows at NASA Langley Research Center. The techniques discussed in this paper include nitric oxide (NO) molecular tagging velocimetry (MTV), nitrogen dioxide photodissociation (NO2-to-NO) MTV, and NO and atomic oxygen (O-atom) Doppler-shift-based velocimetry. Measurements of both single-component and two-component velocity have been performed using these techniques. This paper details the specific application and experiment for which each technique has been used, the facility in which the experiment was performed, the experimental setup, sample results, and a discussion of the lessons learned from each experiment.

  11. High Repetition Rate, LINAC-Based Nuclear Resonance Fluorescence FY 2008 Final Report

    SciTech Connect

    Scott M Watson; Mathew T Kinlaw; James L Jones; Alan W. Hunt; Glen A. Warren

    2008-12-01

    This summarizes the first year of a multi-laboratory/university, multi-year effort focusing on high repetition rate, pulsed LINAC-based nuclear resonance fluorescence (NRF) measurements. Specifically, this FY2008 effort centered on experimentally assessing NRF measurements using pulsed linear electron accelerators, operated at various repetition rates, and identifying specific detection requirements to optimize such measurements. Traditionally, interest in NRF as a detection technology, which continues to receive funding from DHS and DOE/NA-22, has been driven by continuous-wave (CW), Van de Graff-based bremsstrahlung sources. However, in addition to the relatively sparse present-day use of Van de Graff sources, only limited NRF data from special nuclear materials has been presented; there is even less data available regarding shielding effects and photon source optimization for NRF measurements on selected nuclear materials.

  12. A sensitive strategy for the fluorescence detection of DNA methyltransferase activity based on the graphene oxide platform and T7 exonuclease-assisted cyclic signal amplification.

    PubMed

    Ma, Yefei; Chen, Lini; Zhang, Liangliang; Liao, Suqi; Zhao, Jingjin

    2015-06-21

    In this work, a simple fluorescence strategy based on the graphene oxide (GO) platform and T7 exonuclease (T7 Exo)-assisted cyclic signal amplification is developed for the fast and sensitive detection of DNA methyltransferase (MTase) activity and inhibition. In the sensing design, Dam MTase was used as a model analyte. In the presence of Dam MTase, a hairpin probe (HP) was methylated, and then specially recognized and cleaved by Dpn I endonuclease, releasing a ssDNA fragment. The released ssDNA subsequently hybridized with a FAM-labeled signal probe (DP) to form a duplex with a blunt 5'-terminal of DP and a 4-mer overhang at the 5'-end of the released ssDNA. This would trigger the T7 Exo-assisted cyclic signal amplification by repeating the hybridization and digestion of DP, liberating the fluorophore. The liberated fluorophore could not be adsorbed on the GO surface due to low affinity and the fluorescence signal was retained. In contrast, no enzymatic degradation of the DP occurred in the absence of Dam MTase. Thus the intact DP was then adsorbed on the GO surface, resulting in fluorescence quenching. By combining the efficient digestion ability of T7 Exo and the super fluorescence quenching efficiency of GO, the present strategy exhibits a high signal-to-background ratio, providing a satisfying sensitivity for the Dam MTase activity assay. In addition, this method does not require a specific recognition sequence for enzymatic cyclic amplification and dual labels with fluorophore/quencher pairs, making the design easy and low cost. Furthermore, the proposed method was also applied to assay the inhibition of Dam MTase activity. This approach may offer potential applications in clinical diagnostics, drug screening and some other related biomedical research. PMID:25882858

  13. Rapid and quantitative detection of zoonotic influenza A virus infection utilizing coumarin-derived dendrimer-based fluorescent immunochromatographic strip test (FICT).

    PubMed

    Yeo, Seon-Ju; Huong, Dinh Thi; Hong, Nguyen Ngoc; Li, Chun-Ying; Choi, Kyunghan; Yu, Kyoungsik; Choi, Du-Young; Chong, Chom-Kyu; Choi, Hak Soo; Mallik, Shyam Kumar; Kim, Hak Sung; Sung, Haan Woo; Park, Hyun

    2014-01-01

    Great efforts have been made to develop robust signal-generating fluorescence materials which will help in improving the rapid diagnostic test (RDT) in terms of sensitivity and quantification. In this study, we developed coumarin-derived dendrimer-based fluorescent immunochromatographic strip test (FICT) assay with enhanced sensitivity as a quantitative diagnostic tool in typical RDT environments. The accuracy of the proposed FICT was compared with that of dot blot immunoassay techniques and conventional RDTs. Through conjugation of coumarin-derived dendrimers with latex beads, fluorescent emission covering broad output spectral ranges was obtained which provided a distinct advantage of easy discrimination of the fluorescent emission of the latex beads with a simple insertion of a long-pass optical filter away from the excitation wavelength. The newly developed FICT assay was able to detect 100 ng/10 ?L of influenza A nucleoprotein (NP) antigen within 5 minutes, which corresponded to 2.5-fold higher sensitivity than that of the dot blot immunoassay or conventional RDTs. Moreover, the FICT assay was confirmed to detect at least four avian influenza A subtypes (H5N3, H7N1, H7N7, and H9N2). On applying the FICT to the clinical swab samples infected with respiratory viruses, our FICT assay was confirmed to differentiate influenza H1N1 infection from other respiratory viral diseases. These data demonstrate that the proposed FICT assay is able to detect zoonotic influenza A viruses with a high sensitivity, and it enables the quantitation of the infection intensity by providing the numerical diagnostic values; thus demonstrating enhanced detectability of influenza A viruses. PMID:25285172

  14. Rapid and Quantitative Detection of Zoonotic Influenza A Virus Infection Utilizing Coumarin-derived dendrimer-based Fluorescent Immunochromatographic Strip Test (FICT)

    PubMed Central

    Yeo, Seon-Ju; Huong, Dinh Thi; Hong, Nguyen Ngoc; Li, Chun-Ying; Choi, Kyunghan; Yu, Kyoungsik; Choi, Du-Young; Chong, Chom-Kyu; Choi, Hak Soo; Mallik, Shyam Kumar; Kim, Hak Sung; Sung, Haan Woo; Park, Hyun

    2014-01-01

    Great efforts have been made to develop robust signal-generating fluorescence materials which will help in improving the rapid diagnostic test (RDT) in terms of sensitivity and quantification. In this study, we developed coumarin-derived dendrimer-based fluorescent immunochromatographic strip test (FICT) assay with enhanced sensitivity as a quantitative diagnostic tool in typical RDT environments. The accuracy of the proposed FICT was compared with that of dot blot immunoassay techniques and conventional RDTs. Through conjugation of coumarin-derived dendrimers with latex beads, fluorescent emission covering broad output spectral ranges was obtained which provided a distinct advantage of easy discrimination of the fluorescent emission of the latex beads with a simple insertion of a long-pass optical filter away from the excitation wavelength. The newly developed FICT assay was able to detect 100 ng/10 ?L of influenza A nucleoprotein (NP) antigen within 5 minutes, which corresponded to 2.5-fold higher sensitivity than that of the dot blot immunoassay or conventional RDTs. Moreover, the FICT assay was confirmed to detect at least four avian influenza A subtypes (H5N3, H7N1, H7N7, and H9N2). On applying the FICT to the clinical swab samples infected with respiratory viruses, our FICT assay was confirmed to differentiate influenza H1N1 infection from other respiratory viral diseases. These data demonstrate that the proposed FICT assay is able to detect zoonotic influenza A viruses with a high sensitivity, and it enables the quantitation of the infection intensity by providing the numerical diagnostic values; thus demonstrating enhanced detectability of influenza A viruses. PMID:25285172

  15. Chip-scale fluorescence microscope based on a silo-filter complementary metal-oxide semiconductor image sensor

    E-print Network

    Yang, Changhuei

    Chip-scale fluorescence microscope based on a silo-filter complementary metal-oxide semiconductor microscope. The extruded pixel design with metal walls between neighboring pixels guides fluores- cence-based epifluorescence microscopes have long been standard equipment in biological imaging de- spite their inherent

  16. Open flower fluoroimmunoassay: a general method to make fluorescent protein-based immunosensor probes.

    PubMed

    Chung, Chan-I; Makino, Ryoji; Dong, Jinhua; Ueda, Hiroshi

    2015-03-17

    Fluorescence-based probes, especially those that utilize Förster resonance energy transfer (FRET) between fluorescent protein (FP) variants, are widely used to monitor various biological phenomena, most often detecting its ligand-induced conformational change through the receptor domain. While antibody provides a fertile resource of a specific receptor for various biomolecules, its potential has not been fully exploited. An exception is a pair of donor FP-fused VH and acceptor FP-fused VL fragments, which has been proven useful when their association increases in the presence of antigen (open sandwich fluoroimmunoassay, OS-FIA). However, probes for larger proteins such as serum albumin (SA) were difficult to produce, since the interaction between VH and VL of these antibodies is barely affected by the bound antigen. Here, we propose a novel strategy, called open flower fluoroimmunoassay (OF-FIA), using a probe composed of a donor-fused VH and an acceptor-fused VL linked by a disulfide bond between VH and VL (CyPet/YPet-dsFv). The probe gave high FRET efficiency due to the dimerization propensity of the FP pair, while the efficiency got lower as SA concentration increased, probably due to dimer disruption. The constructed probe could detect clinically relevant range of SA, showing its potential as a diagnostic reagent. PMID:25686487

  17. Highly sensitive immunoassay of protein molecules based on single nanoparticle fluorescence detection in a nanowell

    NASA Astrophysics Data System (ADS)

    Han, Jin-Hee; Kim, Hee-Joo; Lakshmana, Sudheendra; Gee, Shirley J.; Hammock, Bruce D.; Kennedy, Ian M.

    2011-03-01

    A nanoarray based-single molecule detection system was developed for detecting proteins with extremely high sensitivity. The nanoarray was able to effectively trap nanoparticles conjugated with biological sample into nanowells by integrating with an electrophoretic particle entrapment system (EPES). The nanoarray/EPES is superior to other biosensor using immunoassays in terms of saving the amounts of biological solution and enhancing kinetics of antibody binding due to reduced steric hindrance from the neighboring biological molecules. The nanoarray patterned onto a layer of PMMA and LOL on conductive and transparent indium tin oxide (ITO)-glass slide by using e-beam lithography. The suspension of 500 nm-fluorescent (green emission)-carboxylated polystyrene (PS) particles coated with protein-A followed by BDE 47 polyclonal antibody was added to the chip that was connected to the positive voltage. The droplet was covered by another ITO-coated-glass slide and connected to a ground terminal. After trapping the particles into the nanowells, the solution of different concentrations of anti-rabbit- IgG labeled with Alexa 532 was added for an immunoassay. A single molecule detection system could quantify the anti-rabbit IgG down to atto-mole level by counting photons emitted from the fluorescent dye bound to a single nanoparticle in a nanowell.

  18. High Repetition Rate, LINAC-based Nuclear Resonance Fluorescence FY 2009 Final Report

    SciTech Connect

    Mathew Kinlaw; Scott Watson; James Johnson; Alan Hunt; Heather Seipel; Edward Reedy

    2009-10-01

    Nuclear Resonance Fluorescence (NRF), which is possible for nuclei with atomic numbers greater than helium (Z=2), occurs when a nuclear level is excited by resonant absorption of a photon and subsequently decays by reemission of a photon. The excited nuclear states can become readily populated, provided the incident photon’s energy is within the Doppler-broadened width of the energy level being excited. Utilizing continuous energy photon spectra, as is characteristic of a bremsstrahlung photon beam, as the inspection source, ensures that at least some fraction of the impinging beam will contribute to the population of the excited energy levels in the material of interest. Upon de-excitation, either to the ground state or to a lower-energy excited state, the emitted fluorescence photon’s energy will correspond to the energy difference between the excited state and the state to which it decays. As each isotope inherently contains unique nuclear energy levels, the NRF states for each isotope are also unique. By exploiting this phenomenon, NRF photon detection provides a well-defined signature for identifying the presence of individual nuclear species. This report summarizes the second year (Fiscal Year [FY] 2009) of a collaborative research effort between Idaho National Laboratory, Idaho State University’s Idaho Accelerator Center, and Pacific Northwest National Laboratory. This effort focused on continuing to assess and optimize NRF-based detection techniques utilizing a slightly modified, commercially available, pulsed medical electron accelerator.

  19. Development of an underwater multispectral fluorescence based oil spill sensor system for the marine environment

    SciTech Connect

    Andrews, J.M.; Lieberman, S.H. [Naval Command, San Diego, CA (United States)

    1997-06-01

    This poster describes the development of an underwater optical fluorescence sensor system to detect the presence of petroleum hydrocarbon contaminants in the marine environment. The system is designed for long term continuous underwater operation and will be used primarily to provide real time notification of the occurrence of a petroleum leak or spill at marine facilities. The sensor utilizes broadband UV excitation from a pulsed xenon lamp to generate fluorescence emission in contaminated sea water. It can detect floating product (surface sheen) from below the surface as well as detect dissolved phase PAHs in the water column. Multispectral emission information is used to distinguish between several possible petroleum classes and also to eliminate false positive interference from non-petroleum based fluorophores such as chlorophyll, cleaning detergents, and sea dye. Real time qualitative identification yields an important advantage in terms of rapidly resolving questions of spill origin or in determining an appropriate response. The design uses the optical energy of the UV excitation source to prevent biofouling on the surface of the optical window thereby greatly extending the usable field lifetime of the {open_quotes}deploy and forget{close_quotes} instrument.

  20. Mesh-based Monte Carlo code for fluorescence modeling in complex tissues with irregular boundaries

    NASA Astrophysics Data System (ADS)

    Wilson, Robert H.; Chen, Leng-Chun; Lloyd, William; Kuo, Shiuhyang; Marcelo, Cynthia; Feinberg, Stephen E.; Mycek, Mary-Ann

    2011-07-01

    There is a growing need for the development of computational models that can account for complex tissue morphology in simulations of photon propagation. We describe the development and validation of a user-friendly, MATLAB-based Monte Carlo code that uses analytically-defined surface meshes to model heterogeneous tissue geometry. The code can use information from non-linear optical microscopy images to discriminate the fluorescence photons (from endogenous or exogenous fluorophores) detected from different layers of complex turbid media. We present a specific application of modeling a layered human tissue-engineered construct (Ex Vivo Produced Oral Mucosa Equivalent, EVPOME) designed for use in repair of oral tissue following surgery. Second-harmonic generation microscopic imaging of an EVPOME construct (oral keratinocytes atop a scaffold coated with human type IV collagen) was employed to determine an approximate analytical expression for the complex shape of the interface between the two layers. This expression can then be inserted into the code to correct the simulated fluorescence for the effect of the irregular tissue geometry.

  1. Noninvasive and Quantitative Assessment of In Vivo Fetomaternal Interface Angiogenesis Using RGD-Based Fluorescence

    PubMed Central

    Keramidas, M.; Lavaud, J.; Sergent, F.; Hoffmann, P.; Brouillet, S.; Feige, J.-J.; Coll, J.-L.; Alfaidy, N.

    2014-01-01

    Angiogenesis is a key process for proper placental development and for the success of pregnancy. Although numerous in vitro methods have been developed for the assessment of this process, relatively few reliable in vivo methods are available to evaluate this activity throughout gestation. Here we report an in vivo technique that specifically measures placental neovascularization. The technique is based on the measurement of a fluorescent alpha v beta 3 (?v?3) integrin-targeting molecule called Angiolone-Alexa-Fluor 700. The ?v?3 integrin is highly expressed by endothelial cells during the neovascularization and by trophoblast cells during their invasion of the maternal decidua. Angiolone was injected to gravid mice at 6.5 and 11.5 days post coitus (dpc). The fluorescence was analyzed one day later at 7.5 and 12.5?dpc, respectively. We demonstrated that (i) Angiolone targets ?v?3 protein in the placenta with a strong specificity, (ii) this technique is quantitative as the measurement was correlated to the increase of the placental size observed with increasing gestational age, and (iii) information on the outcome is possible, as abnormal placentation could be detected early on during gestation. In conclusion, we report the validation of a new noninvasive and quantitative method to assess the placental angiogenic activity, in vivo. PMID:25110672

  2. An efficient rhodamine thiospirolactam-based fluorescent probe for detection of Hg2+ in aqueous samples.

    PubMed

    Gong, Yi-Jun; Zhang, Xiao-Bing; Chen, Zhuo; Yuan, Yuan; Jin, Zhen; Mei, Lei; Zhang, Jing; Tan, Weihong; Shen, Guo-Li; Yu, Ru-Qin

    2012-02-21

    This paper described the optimized design, synthesis and application of a novel rhodamine thiospirolactam derivative as an 'off-on' fluorescent probe for the detection of Hg(2+) in aqueous samples. The 'off-on' fluorescence and color signal change of the probe is based on an Hg(2+)-triggered domino reaction which brings on the opened-ring form of the rhodamine spirolactam to regain the conjugated system of the rhodamine skeleton. In the well designed probe, the thiospirolactam serves as both Hg(2+) binding unit and electron-defect carbon centre, a phenolic hydroxyl with very strong nucleophilicity after deprotonation is chosen as the attacking unit, and a benzene ring is introduced on the linker to afford steric effects, which benefits an efficient nucleophilic reaction, with a high sensitivity towards Hg(2+). It exhibits a stable response for Hg(2+) from 1.0 × 10(-8) to 1.0 × 10(-6) M, with a detection limit of 3.0 × 10(-9) M. The response of the probe to Hg(2+) is highly selective and pH-insensitive, with a fast response time. All these unique features make it particularly favorable for cellular Hg(2+) imaging applications. It has been preliminarily used for highly sensitive monitoring of Hg(2+) levels in living cells with satisfying resolution. PMID:22179782

  3. A homogeneous, high-throughput fluorescence anisotropy-based DNA supercoiling assay.

    PubMed

    Shapiro, Adam; Jahic, Haris; Prasad, Swati; Ehmann, David; Thresher, Jason; Gao, Ning; Hajec, Laurel

    2010-10-01

    The degree of supercoiling of DNA is vital for cellular processes, such as replication and transcription. DNA topology is controlled by the action of DNA topoisomerase enzymes. Topoisomerases, because of their importance in cellular replication, are the targets of several anticancer and antibacterial drugs. In the search for new drugs targeting topoisomerases, a biochemical assay compatible with automated high-throughput screening (HTS) would be valuable. Gel electrophoresis is the standard method for measuring changes in the extent of supercoiling of plasmid DNA when acted upon by topoisomerases, but this is a low-throughput and laborious method. A medium-throughput method was described previously that quantitatively distinguishes relaxed and supercoiled plasmids by the difference in their abilities to form triplex structures with an immobilized oligonucleotide. In this article, the authors describe a homogeneous supercoiling assay based on triplex formation in which the oligonucleotide strand is labeled with a fluorescent dye and the readout is fluorescence anisotropy. The new assay requires no immobilization, filtration, or plate washing steps and is therefore well suited to HTS for inhibitors of topoisomerases. The utility of this assay is demonstrated with relaxation of supercoiled plasmid by Escherichia coli topoisomerase I, supercoiling of relaxed plasmid by E. coli DNA gyrase, and inhibition of gyrase by fluoroquinolones and nalidixic acid. PMID:20930214

  4. Calixarene-Based Fluorescent Sensors for Cesium Cations Containing BODIPY Fluorophore.

    PubMed

    Depauw, Alexis; Kumar, Naresh; Ha-Thi, Minh-Huong; Leray, Isabelle

    2015-06-11

    New fluorescent molecular sensors based on a calix[4]arene biscrown-6 ether as coordination site and BODIPY derivative as signaling unit were synthesized, and their photophysical properties were characterized. The complexation properties of these sensors with potassium and cesium cations were investigated using both steady-state and time-resolved fluorescence methods. The studies show that the sensitivity with cations depends upon the position of substituted coordination site on the BODIPY core. The complexation with cations does not have much effect on the absorption and emission wavelength when the coordination site (calix[4]arene biscrown-6 ether) is introduced at the meso position of the BODIPY core. In contrast, the same calix[4]arene biscrown-6 ether attached via a styryl linker to the ?-position of BODIPY core leads to a sensitive sensor for alkali cations thanks to the better conjugation between the coordination site and the BODIPY core. The complexation of cations induces a hypsochromic shift of the absorption and emission maximums due to the diminution of donor character of the oxygen atoms in the coordination site. The stability constants of complexes with potassium and cesium ion were measured. PMID:25636436

  5. Isotopic imaging via nuclear resonance fluorescence with laser-based Thomson radiation

    DOEpatents

    Barty, Christopher P. J. (Hayward, CA); Hartemann, Frederic V. (San Ramon, CA); McNabb, Dennis P. (Alameda, CA); Pruet, Jason A. (Brentwood, CA)

    2009-07-21

    The present invention utilizes novel laser-based, high-brightness, high-spatial-resolution, pencil-beam sources of spectrally pure hard x-ray and gamma-ray radiation to induce resonant scattering in specific nuclei, i.e., nuclear resonance fluorescence. By monitoring such fluorescence as a function of beam position, it is possible to image in either two dimensions or three dimensions, the position and concentration of individual isotopes in a specific material configuration. Such methods of the present invention material identification, spatial resolution of material location and ability to locate and identify materials shielded by other materials, such as, for example, behind a lead wall. The foundation of the present invention is the generation of quasimonochromatic high-energy x-ray (100's of keV) and gamma-ray (greater than about 1 MeV) radiation via the collision of intense laser pulses from relativistic electrons. Such a process as utilized herein, i.e., Thomson scattering or inverse-Compton scattering, produces beams having diameters from about 1 micron to about 100 microns of high-energy photons with a bandwidth of .DELTA.E/E of approximately 10E.sup.-3.

  6. Miniature fiber optic spectrometer-based quantitative fluorescence resonance energy transfer measurement in single living cells

    NASA Astrophysics Data System (ADS)

    Chai, Liuying; Zhang, Jianwei; Zhang, Lili; Chen, Tongsheng

    2015-03-01

    Spectral measurement of fluorescence resonance energy transfer (FRET), spFRET, is a widely used FRET quantification method in living cells today. We set up a spectrometer-microscope platform that consists of a miniature fiber optic spectrometer and a widefield fluorescence microscope for the spectral measurement of absolute FRET efficiency (E) and acceptor-to-donor concentration ratio (RC) in single living cells. The microscope was used for guiding cells and the spectra were simultaneously detected by the miniature fiber optic spectrometer. Moreover, our platform has independent excitation and emission controllers, so different excitations can share the same emission channel. In addition, we developed a modified spectral FRET quantification method (mlux-FRET) for the multiple donors and multiple acceptors FRET construct (mD˜nA) sample, and we also developed a spectra-based 2-channel acceptor-sensitized FRET quantification method (spE-FRET). We implemented these modified FRET quantification methods on our platform to measure the absolute E and RC values of tandem constructs with different acceptor/donor stoichiometries in single living Huh-7 cells.

  7. Mismatching base-pair dependence of the kinetics of DNA–DNA hybridization studied by surface plasmon fluorescence spectroscopy

    PubMed Central

    Tawa, Keiko; Knoll, Wolfgang

    2004-01-01

    Two single-stranded DNAs consisting of complementary base pairs except for one mismatching base pair (MM1) can form double-stranded DNA by molecular recognition. This type of duplex is not as stable as that formed by MM0. In order to add to a better understanding of the physical mechanism of the hybridization and dissociation processes at sensor (chip) surfaces, we studied the kinetics of the MM1 hybridization by surface plasmon fluorescence spectroscopy. Target DNA strands labelled with a fluorescent molecule Cy5 at the 5? end and hybridizing with the surface-attached probe DNA can be excited by the strong optical field of a surface plasmon resonance mode. The emitted fluorescence can be detected with high sensitivity. The affinity of a duplex was found to depend on the chemical nature, i.e. G–G, G–T etc., and on the position of the mismatching base pair along the 15mer duplex. PMID:15115799

  8. A carbon dot-based "off-on" fluorescent probe for highly selective and sensitive detection of phytic acid.

    PubMed

    Gao, Zhao; Wang, Libing; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

    2015-08-15

    We herein report a facile, one-step pyrolysis synthesis of photoluminescent carbon dots (CDs) using citric acid as the carbon source and lysine as the surface passivation reagent. The as-prepared CDs show narrow size distribution, excellent blue fluorescence and good photo-stability and water dispersivity. The fluorescence of the CDs was found to be effectively quenched by ferric (Fe(III)) ions with high selectivity via a photo-induced electron transfer (PET) process. Upon addition of phytic acid (PA) to the CDs/Fe(III) complex dispersion, the fluorescence of the CDs was significantly recovered, arising from the release of Fe(III) ions from the CDs/Fe(III) complex because PA has a higher affinity for Fe(III) ions compared to CDs. Furthermore, we developed an "off-on" fluorescence assay method for the detection of phytic acid using CDs/Fe(III) as a fluorescent probe. This probe enables the selective detection of PA with a linear range of 0.68-18.69?M and a limit of detection (signal-to-noise ratio is 3) of 0.36?M. The assay method demonstrates high selectivity, repeatability, stability and recovery ratio in the detection of the standard and real PA samples. We believe that the facile operation, low-cost, high sensitivity and selectivity render this CD-based "off-on" fluorescent probe an ideal sensing platform for the detection of PA. PMID:25829220

  9. Ultrashort fluorescence lifetimes of hydrogen-bonded base pairs of guanosine and cytidine in solution.

    PubMed

    Schwalb, Nina K; Michalak, Thomas; Temps, Friedrich

    2009-12-24

    The optically excited electronic states of hydrogen-bonded homo- and heterodimers of guanosine (G) and deoxycytidine (C) were investigated by femtosecond fluorescence up-conversion spectroscopy. The base pairs were prepared in CHCl(3) solution by employing tert-butyldimethylsilyl (TBDMS) groups at the OH positions of the ribose (G) or deoxyribose (C) moieties to enhance the solubilities of the nucleosides in organic solvents. The H-bonded complexes that were obtained were characterized by FTIR spectroscopy. Fluorescence lifetime measurements were performed following electronic excitation at a series of UV wavelengths from lambda(pump) = 294 nm, close to the electronic origins of the bases, to lambda(pump) = 262 nm, where significant excess vibronic energy is deposited in the molecules, at nucleoside concentrations of c(0) = 0.1 and 1.0 mM. The experimental results revealed the existence of an ultrafast deactivation pathway for the optically prepared electronically excited state(s) of the G.C Watson-Crick base pair, which was found to have a lifetime of tau(GC) = 0.30(3) ps (with 2sigma error limits) irrespective of the pump wavelength. A similar short decay time, tau(GG) = 0.32(2) ps, was observed for the respective excited G.G homodimer. In contrast, the excited G monomer displayed a significantly longer-lived and wavelength-dependent deactivation, requiring three time constants, between 0.43(6) ps < or = tau(G,1) < or = 1.2(1) ps, 4.2(8) ps < or = tau(G,2) < or = 8(1) ps, and tau(G,3) = 195(32) ps. Self-complexation of C, on the other hand, led to a longer-lived excited state with a lifetime estimated between 1 ps < or = tau(CC) < or = 10 ps, compared to the dominant initial subpicosecond decay time of the C monomer of tau(C,1) = 0.80(4) ps. PMID:19947627

  10. A simple approximation algorithm for WIS based on the approximability in k-partite

    E-print Network

    Paris-Sud XI, Université de

    A simple approximation algorithm for WIS based on the approximability in k-partite graphs Jérôme}@lamsade.dauphine.fr Cahiers du LAMSADE 1 #12;1 Introduction In the Maximum Weighted Independent Set problem (WIS, for short of vertices, we denote by w(S) = vS w(v) the sum of the weights of the elements in S. The goal of WIS

  11. A simple extraction method suitable for PCR-based analysis of plant, fungal, and bacterial DNA

    Microsoft Academic Search

    George S. Mahuku

    2004-01-01

    A simple and easy protocol for extracting high-quality DNA from microorganisms and plants is presented. The method involves\\u000a inactivating proteins by using SDS\\/proteinase K and precipitating polysaccharides in the presence of high salt. Further purification\\u000a is based on differential solubility of DNA and high-molecular-weight polysaccharides in aqueous media. The procedure does\\u000a not use the toxic and potentially hazardous phenol and

  12. A simple three-input DNA-based system works as a full-subtractor

    PubMed Central

    Lin, Hung-Yin; Chen, Jian-Zhou; Li, Hao-Yi; Yang, Chia-Ning

    2015-01-01

    Over the past decade, DNA has demonstrated remarkable potential in fabrication of molecular logic and arithmetic systems. In this work, a simple DNA-based system mimicking a full-subtractor that handles three inputs including one minuend and two subtrahends for eight input/output conditions is successfully designed. The whole system is established by one gate molecule and three input sequences, all made of single-stranded DNA sequences. PMID:26095534

  13. A simple spreadsheet-based, MIAME-supportive format for microarray data: MAGE-TAB

    Microsoft Academic Search

    Tim F. Rayner; Philippe Rocca-serra; Paul T. Spellman; Helen C. Causton; Anna Farne; Ele Holloway; Rafael A. Irizarry; Junmin Liu; Donald S Maier; Michael Miller; Kjell Petersen; John Quackenbush; Gavin Sherlock; Christian J. Stoeckert Jr.; Joseph White; Patricia L. Whetzel; Farrell Wymore; Helen E. Parkinson; Ugis Sarkans; Catherine A. Ball; Alvis Brazma

    2006-01-01

    Background: Sharing of microarray data within the research community has been greatly facilitated by the development of the disclosure and communication standards MIAME and MAGE- ML by the MGED Society. However, the complexity of the MAGE-ML format has made its use impractical for laboratories lacking dedicated bioinformatics support. Results: We propose a simple tab-delimited, spreadsheet-based format, MAGE-TAB, which will become

  14. Mobile display-based manipulation: an intuitive and interactive technique for manipulating simple robots

    Microsoft Academic Search

    Kazuhiro Hosoi; Vinh Ninh Dao; Akihiro Mori; Masanori Sugimoto

    2008-01-01

    In this paper, we propose the Mobile Display-based Manipulation (MDM) technique for manipulating simple robots such as automated cleaning robots. By capturing images of robots with a camera-attached mobile display and moving it in a three-dimensional space, a user can easily and intuitively manipulate the robots. To verify the validity and effects of the MDM technique, we developed two prototype

  15. A simple three-input DNA-based system works as a full-subtractor.

    PubMed

    Lin, Hung-Yin; Chen, Jian-Zhou; Li, Hao-Yi; Yang, Chia-Ning

    2015-01-01

    Over the past decade, DNA has demonstrated remarkable potential in fabrication of molecular logic and arithmetic systems. In this work, a simple DNA-based system mimicking a full-subtractor that handles three inputs including one minuend and two subtrahends for eight input/output conditions is successfully designed. The whole system is established by one gate molecule and three input sequences, all made of single-stranded DNA sequences. PMID:26095534

  16. PLGA-based microparticles: elucidation of mechanisms and a new, simple mathematical model quantifying drug release

    Microsoft Academic Search

    N. Faisant; J. Siepmann; J. P. Benoit

    2002-01-01

    The two major aims of this study were: (i) to elucidate the underlying release mechanisms from drug-loaded, erodible microparticles based on poly(lactic-co-glycolic acid) (PLGA) showing biphasic drug release behavior: an initial ‘burst’ effect, followed by a zero order release phase; and (ii) to develop a new, simple mathematical model that allows the quantitative description of the observed in vitro drug

  17. Electrochemical immobilization of Fluorescent labelled probe molecules on a FTO surface for affinity detection based on photo-excited current

    NASA Astrophysics Data System (ADS)

    Haruyama, Tetsuya; Wakabayashi, Ryo; Cho, Takeshi; Matsuyama, Sho-taro

    2011-10-01

    Photo-excited current can be generated at a molecular interface between a photo-excited molecules and a semi-conductive material in appropriate condition. The system has been recognized for promoting photo-energy devices such as an organic dye sensitized solar-cell. The photo-current generated reactions are totally dependent on the interfacial energy reactions, which are in a highly fluctuated interfacial environment. The authors investigated the photo-excited current reaction to develop a smart affinity detection method. However, in order to perform both an affinity reaction and a photo-excited current reaction at a molecular interface, ordered fabrications of the functional (affinity, photo-excitation, etc.) molecules layer on a semi-conductive surface is required. In the present research, we would like to present the fabrication and functional performance of photo-excited current-based affinity assay device and its application for detection of endocrine disrupting chemicals. On the FTO surface, fluorescent pigment labelled affinity peptide was immobilized through the EC tag (electrochemical-tag) method. The modified FTO produced a current when it was irradiated with diode laser light. However, the photo current decreased drastically when estrogen (ES) coexisted in the reaction solution. In this case, immobilized affinity probe molecules formed a complex with ES and estrogen receptor (ER). The result strongly suggests that the photo-excited current transduction between probe molecule-labelled cyanine pigment and the FTO surface was partly inhibited by a complex that formed at the affinity oligo-peptide region in a probe molecule on the FTO electrode. The bound bulky complex may act as an impediment to perform smooth transduction of photo-excited current in the molecular interface. The present system is new type of photo-reaction-based analysis. This system can be used to perform simple high-sensitive homogeneous assays.

  18. A simple routine for quantitative analysis of light and dark kinetics of photochemical and non-photochemical quenching of chlorophyll fluorescence in intact leaves.

    PubMed

    Vredenberg, Wim

    2015-04-01

    Paper describes principles and application of a novel routine that enables the quantitative analysis of the photochemical O-J phase of the variable fluorescence F v associated with the reversible photo-reduction of the secondary electron acceptor QA of photosystem II (PSII) in algae and intact leaves. The kinetic parameters that determine the variable fluorescence F (PP)(t) associated with the release of photochemical quenching are estimated from 10 µs time-resolved light-on and light-off responses of F v induced by two subsequent light pulses of 0.25 (default) and 1000 ms duration, respectively. Application of these pulses allows estimations of (i) the actual value of the rate constants k L and k AB of the light excitation (photoreduction of QA) and of the dark re-oxidation of photoreduced QA ([Formula: see text]), respectively, (ii) the actual maximal normalized variable fluorescence [nF v] associated with 100 % photoreduction of QA of open RCs, and (iii) the actual size ? of RCs in which the re-oxidation of [Formula: see text] is largely suppressed (QB-nonreducing RC with k AB ~ 0). The rate constants of the dark reversion of Fv associated with the release of photo-electrochemical quenching F (PE) and photo-electric stimulation F (CET) in the successive J-I and I-P parts of the thermal phase are in the range of (100 ms)(-1) and (1 s)(-1), respectively. The kinetics of fluorescence changes during and after the I-P phase are given special attention in relation to the hypothesis on the involvement of a ?µ H+-dependent effect during this phase and thereafter. Paper closes with author's personal view on the demands that should be fulfilled for chlorophyll fluorescence methods being a correct and unchallenged signature of photosynthesis in algae and plants. PMID:25739901

  19. Fluorescent refrigeration

    DOEpatents

    Epstein, R.I.; Edwards, B.C.; Buchwald, M.I.; Gosnell, T.R.

    1995-09-05

    Fluorescent refrigeration is based on selective radiative pumping, using substantially monochromatic radiation, of quantum excitations which are then endothermically redistributed to higher energies. Ultimately, the populated energy levels radiatively deexcite emitting, on the average, more radiant energy than was initially absorbed. The material utilized to accomplish the cooling must have dimensions such that the exciting radiation is strongly absorbed, but the fluorescence may exit the material through a significantly smaller optical pathlength. Optical fibers and mirrored glasses and crystals provide this requirement. 6 figs.

  20. Bright or dark immune complexes of anti-TAMRA antibodies for adapted fluorescence-based bioanalysis.

    PubMed

    Eisold, Ursula; Sellrie, Frank; Schenk, Jörg A; Lenz, Christine; Stöcklein, Walter F M; Kumke, Michael U

    2015-05-01

    Fluorescence labels, for example fluorescein or rhodamin derivatives, are widely used in bioanalysis applications including lateral-flow assays, PCR, and fluorescence microscopy. Depending on the layout of the particular application, fluorescence quenching or enhancement may be desired as the detection principle. Especially for multiplexed applications or high-brightness requirements, a tunable fluorescence probe can be beneficial. The alterations in the photophysics of rhodamine derivatives upon binding to two different anti-TAMRA antibodies were investigated by absorption and fluorescence-spectroscopy techniques, especially determining the fluorescence decay time and steady-state and time-resolved fluorescence anisotropy. Two monoclonal anti-TAMRA antibodies were generated by the hybridoma technique. Although surface-plasmon-resonance measurements clearly proved the high affinity of both antibodies towards 5-TAMRA, the observed effects on the fluorescence of rhodamine derivatives were very different. Depending on the anti-TAMRA antibody either a strong fluorescence quenching (G71-DC7) or a distinct fluorescence enhancement (G71-BE11) upon formation of the immune complex was observed. Additional rhodamine derivatives were used to gain further information on the binding interaction. The data reveal that such haptens as 5-TAMRA could generate different paratopes with equal binding affinities but different binding interactions, which provide the opportunity to adapt bioanalysis methods including immunoassays for optimized detection principles for the same hapten depending on the specific requirements. PMID:25711988

  1. Intrinsic fluorescent recognition ligand scaffold based on chaperonins and water-soluble semiconductor quantum dots

    NASA Astrophysics Data System (ADS)

    Xie, Hongzhi; Swanson, Basil I.; Kawaga, Hiromi K.; Trent, Jonathan D.; Kumara, Mudalige; Ippolito, Thomas; Cotlet, Mircea

    2009-02-01

    We describe genetic engineering of a novel protein-nanoparticle hybrid system with great potential for patterning of various types of nanoparticles and for biosensing applications. The hybrid system is based on a genetically-modified chaperonin protein from the hyperthermophilic archaeon Sulfolobus shibatae. This chaperonin is an 18-subunit double ring, which self-assembles in the presence of Mg ions and ATP. We describe a chaperonin mutant (His-?- loopless:HBLL), with increased access to the central cavity and His-tags on each subunit extending into the central cavity. This mutant binds water-soluble semiconductor quantum dots, creating a protein-encapsulated fluorescent nanoparticle. By adding selective binding sites to the solvent-exposed regions of the chaperonin, this proteinnanoparticle bioconjugate becomes a sensor for specific targets. Using a combination of biochemical and spectroscopic assays, we characterize the formation, stoichiometry, affinity and stability of these novel sensors.

  2. High efficiency fluorescent excimer lamps: An alternative to mercury based UVC lamps

    NASA Astrophysics Data System (ADS)

    Masoud, N. M.; Murnick, D. E.

    2013-12-01

    A high efficiency xenon excimer lamp radiating at 172 nm, with an internal phosphor coating shifting to UVC has been demonstrated, showing the feasibility of a cost effective alternative to UVC mercury lamps. Fluorescent lamps so designed can be fabricated in various geometries with high efficiency. Unlike other xenon excimer lamps based on dielectric barrier discharges this new system is highly compatible with existing and proposed phosphors as it operates in an inert gas environment at modest temperature and is subject only to 172 nm primary radiation. Using a lamp coated with a UVC phosphor we have demonstrated the feasibility of germicidal and curing lamps with 40% energy conversion efficiency and high power density. These lamps are rapidly switchable, have long projected lifetimes and are compatible with dimmers.

  3. High efficiency fluorescent excimer lamps: an alternative to mercury based UVC lamps.

    PubMed

    Masoud, N M; Murnick, D E

    2013-12-01

    A high efficiency xenon excimer lamp radiating at 172 nm, with an internal phosphor coating shifting to UVC has been demonstrated, showing the feasibility of a cost effective alternative to UVC mercury lamps. Fluorescent lamps so designed can be fabricated in various geometries with high efficiency. Unlike other xenon excimer lamps based on dielectric barrier discharges this new system is highly compatible with existing and proposed phosphors as it operates in an inert gas environment at modest temperature and is subject only to 172 nm primary radiation. Using a lamp coated with a UVC phosphor we have demonstrated the feasibility of germicidal and curing lamps with 40% energy conversion efficiency and high power density. These lamps are rapidly switchable, have long projected lifetimes and are compatible with dimmers. PMID:24387421

  4. Synthesis, characterization and fluorescence studies of novel bi-phenyl based acrylate and methacrylate

    NASA Astrophysics Data System (ADS)

    Baskar, R.; Subramanian, K.

    2011-09-01

    4-[(1 E)-3-(biphenyl-4-yl)buta-1,3-dien-1-yl]phenyl prop-2-enoate ( ACH) and 4-[(1 E)-3-(biphenyl-4-yl)buta-1,3-dien-1-yl]phenyl 2-methylprop-2-enoate ( MCH) was synthesized from biphenyl in three steps and their structures were confirmed by elemental analysis, IR, NMR ( 1H, 13C, DEPT135, 1H- 1H COSY, 1H- 13C HSQC and 1H- 13C HMBC) spectroscopic techniques. In this present study, various physicochemical characteristics we demonstrate solubility, color, absorbance and fluorescence property of novel biphenyl based acrylate and methacrylate measured in different solvents like benzene, dichloromethane, tetrahydrofuran, acetonitrile, dimethylsulfoxide and ethanol.

  5. Synthesis, characterization and fluorescence studies of novel bi-phenyl based acrylate and methacrylate.

    PubMed

    Baskar, R; Subramanian, K

    2011-09-01

    4-[(1E)-3-(biphenyl-4-yl)buta-1,3-dien-1-yl]phenyl prop-2-enoate (ACH) and 4-[(1E)-3-(biphenyl-4-yl)buta-1,3-dien-1-yl]phenyl 2-methylprop-2-enoate (MCH) was synthesized from biphenyl in three steps and their structures were confirmed by elemental analysis, IR, NMR (1H, 13C, DEPT135, 1H-1H COSY, 1H-13C HSQC and 1H-13C HMBC) spectroscopic techniques. In this present study, various physicochemical characteristics we demonstrate solubility, color, absorbance and fluorescence property of novel biphenyl based acrylate and methacrylate measured in different solvents like benzene, dichloromethane, tetrahydrofuran, acetonitrile, dimethylsulfoxide and ethanol. PMID:21703915

  6. Carbazole-based organogel as a scaffold to construct energy transfer arrays with controllable fluorescence emission.

    PubMed

    Yang, Xinchun; Lu, Ran; Xue, Pengchong; Li, Bin; Xu, Defang; Xu, Tinghua; Zhao, Yingying

    2008-12-01

    A diaryldiketopyrrolopyrrole derivative functionalized with phenothiazine moieties (DPPP) was synthesized and introduced into the ordered 4-(3,6-di-tert-butyl-9H-carbazol-9-yl)benzamide (TBCB) organogel system. It was found that TBCB-based gel became a scaffold to make DPPP molecules line up along the gel fibers, resulting in new self-assembled arrays, whose XRD patterns were quite different from those of the neat TBCB gel and DPPP crystal. In the composite gel, the occurrence of a partial energy transfer from the excited light-harvesting antenna of TBCB to the DPPP acceptor was confirmed on the basis of time-dependent and time-resolved fluorescence investigations. Remarkably, the composite gel could emit intense red light or purplish white light by tuning the excitation wavelength. Such ordered soft materials with color-tunable emission may possess potential applications in sensor and photonic devices. PMID:18980355

  7. A liposomal fluorescence assay to study permeation kinetics of drug-like weak bases across the lipid bilayer.

    PubMed

    Eyer, Klaus; Paech, Franziska; Schuler, Friedrich; Kuhn, Phillip; Kissner, Reinhard; Belli, Sara; Dittrich, Petra S; Krämer, Stefanie D

    2014-01-10

    Lipid bilayer permeation is considered the major route for in vivo barrier passage of drugs. Despite this fact, no technique is currently available to measure the kinetics of permeation across a single lipid bilayer of structurally unrelated drug-like solutes. We developed a liposomal fluorescence assay capable to determine permeation kinetics of basic drug-like solutes across lipid bilayers. The assay is based on the hypothesis that permeation of a weak base along a concentration gradient results in net proton release at the cis-side and net proton capture at the trans-side of the bilayer. The resulting pH changes were monitored with pH-sensitive fluorophores: Test compounds were incubated with liposomes containing a pH-sensitive fluorophore at the bilayer surfaces or in the aqueous lumen and fluorescence changes were monitored with a stopped-flow apparatus in solution or by total internal reflection fluorescence microscopy with surface-captured liposomes on a microfluidic platform. Incubation with lipophilic basic drugs resulted in the expected fluorescence changes while incubation with compounds without basic functionality or high polarity did not affect fluorescence. Kinetics of fluorescence changes followed bi-exponential functions. Logarithmic permeation coefficients (logPermapp) determined in solution and by microfluidics technology showed a good correlation (r(2)=0.94, n=7) and logPermapp increased with increasing lipophilicity. Neither diffusion in the aqueous phase nor partitioning into the bilayer was rate-limiting. PEGylation of 2% of the liposomal lipids reduced Permapp by a factor ~300. In conclusion, the presented liposomal fluorescence assay is capable to determine permeation kinetics of weak basic drug-like solutes across lipid bilayers. The method is adaptable to microfluidics technology for high-throughput measurements and can potentially be modified to work for weak acid solutes. PMID:24211703

  8. Pulse filtering and correction for CZT detectors using simple digital algorithms based on the wavelet transform

    SciTech Connect

    Perez, J.M. [CIEMAT, Madrid (Spain); Garcia-Belmonte, G. [Univ. Jaume 1, Castellon (Spain). Dept. de Ciencies Experimentals

    1998-12-31

    The authors report an approach to double gaussian filtering used in classical works as dual parameter pulse processing. This technique has been implemented by creating a bank of gaussian-like digital filters based on wavelet transforms. A simple method to correct for the charge loss inherent to room temperature semiconductor gamma detectors has been developed. This method is based on multi-resolution signal analysis. Results are reported from tests of these algorithms on commercial CZT detectors and two trapped hole charge correction levels are compared. Finally, the advantages and limitations of this new approach to detector pulse processing are discussed.

  9. Effects of communication and utility-based decision making in a simple model of evacuation

    NASA Astrophysics Data System (ADS)

    Smyrnakis, M.; Galla, T.

    2012-11-01

    We present a simple cellular automaton based model of decision making during evacuation. Evacuees have to choose between two different exit routes, resulting in a strategic decision making problem. Agents take their decisions based on utility functions, these can be revised as the evacuation proceeds, leading to complex interaction between individuals and to jamming transitions. The model also includes the possibility to communicate and exchange information with distant agents, information received may affect the decision of agents. We show that under a wider range of evacuation scenarios performance of the model system as a whole is optimal at an intermediate fraction of evacuees with access to communication.

  10. A water-soluble fluorescent fluoride ion probe based on Alizarin Red S-Al(III) complex

    NASA Astrophysics Data System (ADS)

    Sai Sathish, R.; Ravi Kumar, M.; Nageswara Rao, G.; Anil Kumar, K.; Janardhana, C.

    2007-02-01

    A new water-soluble fluorescent fluoride ion signaling system has been developed based on the ligand exchange mechanism in aqueous medium. This procedure is based on the exchange of two Alizarin Red S (ARS) molecules coordinated to Al(III) by fluoride ion without interference from other common anions. The binary complex of ARS with Al(III) provides a sensitive signaling system for fluoride ion in the concentration range from 5 × 10 -6 to 3 × 10 -4 M. The ligand exchange reaction of ARS-Al(III) complex with fluoride ion has been investigated by UV-vis and fluorescence spectroscopies combined with the AM1 semi-empirical quantum chemical calculations. The pale orange fluorescence ( ?max = 575 nm) exhibited by the complex upon excitation at 435 nm decreases in intensity with fluoride addition with a detection limit of 0.1 mg L -1.

  11. Intravascular atherosclerotic imaging with combined fluorescence and optical coherence tomography probe based on a double-clad fiber combiner

    PubMed Central

    Liang, Shanshan; Saidi, Arya; Jing, Joe; Liu, Gangjun; Li, Jiawen; Zhang, Jun; Sun, Changsen; Narula, Jagat; Chen, Zhongping

    2012-01-01

    Abstract. We developed a multimodality fluorescence and optical coherence tomography probe based on a double-clad fiber (DCF) combiner. The probe is composed of a DCF combiner, grin lens, and micromotor in the distal end. An integrated swept-source optical coherence tomography and fluorescence intensity imaging system was developed based on the combined probe for the early diagnoses of atherosclerosis. This system is capable of real-time data acquisition and processing as well as image display. For fluorescence imaging, the inflammation of atherosclerosis and necrotic core formed with the annexin V–conjugated Cy5.5 were imaged. Ex vivo imaging of New Zealand white rabbit arteries demonstrated the capability of the combined system. PMID:22894457

  12. Determination of benzimidazolic fungicides in fruits and vegetables by supramolecular solvent-based microextraction/liquid chromatography/fluorescence detection.

    PubMed

    Moral, Antonia; Sicilia, María Dolores; Rubio, Soledad

    2009-09-21

    A supramolecular solvent consisting of vesicles, made up of equimolecular amounts of decanoic acid (DeA) and tetrabutylammonium decanoate (Bu4NDe), dispersed in a continuous aqueous phase, is proposed for the extraction of benzimidazolic fungicides (BFs) from fruits and vegetables. Carbendazim (CB), thiabendazole (TB) and fuberidazole (FB) were extracted in a single step and no clean-up or concentration of extracts was needed. The high extraction efficiency obtained for BFs was a result of the different types of interactions provided by the supramolecular solvent (e.g. hydrophobic and hydrogen bonds) and the high number of solubilisation sites it contains. Besides simple and efficient, the proposed extraction approach was rapid, low-cost, environment friendly and it was implemented using conventional lab equipments. The target analytes were determined in the supramolecular extract by LC/fluorescence detection. They were separated in a Kromasil C18 (5 microm, 150 mm x 4.6 mm) column using isocratic elution [mobile phase: 60:40 (v/v) 50 mM phosphate buffer (pH 4)/methanol] and quantified at 286/320 nm (CB) and 300/350 nm (TB and FB) excitation/emission wavelengths, respectively. Quantitation limits provided by the supramolecular solvent-based microextraction (SUSME)/LC/fluorescence detection proposed method for the determination of CB, TB and FB in fruits and vegetables were 14.0, 1.3 and 0.03 microg kg(-1), respectively, values far below the current maximum residue levels (MRLs) established by the European Union, i.e. 100-2000 microg kg(-1) for CB, 50-5000 microg kg(-1) for TB and 50 microg kg(-1) for FB. The precision of the method, expressed as relative standard deviation, for inter-day measurements (n=13) was 3.3% for CB (50 microg kg(-1)), 3.5% for TB (10 microg kg(-1)) and 2.8% for FB (0.5 microg kg(-1)) and recoveries for fruits (oranges, tangerines, lemons, limes, grapefruits, apples, pears and bananas) and vegetables (potatoes and lettuces) fortified at the microg kg(-1) level were in the interval 93-102%. PMID:19720194

  13. A SIMPLE AND EFFICIENT WAVELET-BASED DENOISING ALGORITHM USING JOINT INTER-AND INTRASCALE STATISTICS ADAPTIVELY

    E-print Network

    Mirchandani, Gagan

    A SIMPLE AND EFFICIENT WAVELET-BASED DENOISING ALGORITHM USING JOINT INTER- AND INTRASCALE The University of Vermont Burlington, Vermont 05405, USA ABSTRACT We propose a simple and eÆcient image denoising of thresholding in signal denoising. The general procedure for wavelet-based denoising algorithms consists

  14. Improved conditions for periodate/Schiff's base-based fluorescent staining of glycoproteins with dansylhydrazine in SDS-PAGE.

    PubMed

    Zhou, Xuan; Hong, Guo-Ying; Huang, Bin-Bin; Duan, Yuan-Meng; Shen, Jia-Yi; Ni, Mao-Wei; Cong, Wei-Tao; Jin, Li-Tai

    2014-05-01

    An improved periodate/Schiff's base based fluorescent stain with dansylhydrazine (DH) for glycoproteins in 1D and 2D SDS-PAGE was described. Down to 4-8 ng of glycoproteins can be selectively detected within 2 h, which is approximately 16-fold higher than that of original protocol, but similar to that of Pro-Q Emerald 488 stain (Invitrogen, Carlsbad, USA). Furthermore, subsequent study of deglycosylation, glycoprotein affinity isolation, and LC-MS/MS analysis were performed to confirm the specificity of the improved method. As a result, improved DH stain may provide a new choice for selective, economic, MS compatible, and convenient visualization of gel-separated glycoproteins. PMID:24591039

  15. Fifth Graders' Learning About Simple Machines Through Engineering Design-Based Instruction Using LEGO™ Materials

    NASA Astrophysics Data System (ADS)

    Marulcu, Ismail; Barnett, Mike

    2012-12-01

    This study is part of a 5-year National Science Foundation-funded project, Transforming Elementary Science Learning Through LEGO™ Engineering Design. In this study, we report on the successes and challenges of implementing an engineering design-based and LEGO™-oriented unit in an urban classroom setting and we focus on the impact of the unit on students' content understanding of simple machines. The LEGO™ engineering-based simple machines module, which was developed for fifth graders by our research team, was implemented in an urban school in a large city in the Northeastern region of the USA. Thirty-three fifth grade students participated in the study, and they showed significant growth in content understanding. We measured students' content knowledge by using identical paper tests and semistructured interviews before and after instruction. Our paired t test analysis results showed that students significantly improved their test and interview scores (t = -3.62, p < 0.001 for multiple-choice items and t = -9.06, p < 0.000 for the open-ended items in the test and t = -12.11, p < 0.000 for the items in interviews). We also identified several alternative conceptions that are held by students on simple machines.

  16. A self-adaptive trust region method with line search based on a simple subproblem model

    NASA Astrophysics Data System (ADS)

    Sang, Zhaoyang; Sun, Qingying

    2009-10-01

    In this paper, based on a simple model of the trust region subproblem, we propose a new self-adaptive trust region method with a line search technique for solving unconstrained optimization problems. By use of the simple subproblem model, the new method needs less memory capacitance and computational complexity. And the trust region radius is adjusted with a new self-adaptive adjustment strategy which makes full use of the information at the current point. When the trial step results in an increase in the objective function, the method does not resolve the subproblem, but it performs a line search technique from the failed point. Convergence properties of the method are proved under certain conditions. Numerical experiments show that the new method is effective and attractive for large-scale optimization problems.

  17. A simple filter-based approach to surface enhanced Raman spectroscopy for trace chemical detection.

    PubMed

    Yu, Wei W; White, Ian M

    2012-03-01

    We demonstrate an extremely simple and practical surface enhanced Raman spectroscopy (SERS) technique for trace chemical detection. Filter membranes first trap silver nanoparticles to form a SERS-active substrate and then concentrate analytes from a mL-scale sample into a ?L-scale detection volume. We demonstrate a significant improvement in detection limit as compared to colloidal SERS for the pesticide malathion and the food contaminant melamine. The measured SERS intensity exhibits low variation relative to traditional SERS techniques, and the data can be closely fit with a Langmuir isotherm. Thus, due to the simple procedure, the low-cost of the substrates, the quantitative results, and the performance improvement due to analyte concentration, our technique enables SERS to be practical for a broad range of analytical applications, including field-based detection of toxins in large-volume samples. PMID:22282766

  18. Polyethylenimine-based transfection method as a simple and effective way to produce recombinant lentiviral vectors.

    PubMed

    Toledo, Jorge R; Prieto, Yanet; Oramas, Nayrobis; Sánchez, Oliberto

    2009-06-01

    HIV-1-derived lentiviral vectors (LvV) are within the most attractive gene delivery vehicles in the context of both dividing and quiescent cells. LvV is currently produced by the conventional calcium phosphate precipitation method. Nevertheless, this procedure is highly susceptible to variations in pH and impurities, which lead to inconsistencies in LvV production. Here, we present a simple and robust procedure for LvV production using branched 25 kDa polyethylenimine, with a transfection efficiency of over 90% and viral titer yields of about 1 x 10(7) infective lentiviral particles per milliliter. The procedure outlined is simple, consistent, and as inexpensive as the CaPO(4)-based method. PMID:19089654

  19. Integrated fluorescent light source for optofluidic applications

    NASA Astrophysics Data System (ADS)

    Vezenov, Dmitri V.; Mayers, Brian T.; Wolfe, Daniel B.; Whitesides, George M.

    2005-01-01

    This letter describes a simple fluidic light source for use "on-chip" in integrated microsystems. It demonstrates the feasibility of light sources based on liquid-core, liquid-cladding (L2) microchannel waveguides, with liquid cores containing fluorescent dyes. These fluorescent light sources, using both miscible and two-phase systems, are tunable in terms of the beam size, intensity and spectral content. The observed output intensity from fluorescent L2 light sources is comparable to standard fiber optic spectrophotometer light sources. Integration of fluorescent light sources during device fabrication removes both the need for insertion and alignment of conventional, optical-fiber light sources and the constraints on channel size imposed by fiber optics, albeit at the cost of establishing a microfluidic infrastructure.

  20. Fluorescent sensor for selective detection of Al3+ based on quinoline-coumarin conjugate

    NASA Astrophysics Data System (ADS)

    Qin, Jing-can; Li, Tian-rong; Wang, Bao-dui; Yang, Zheng-yin; Fan, Long

    2014-12-01

    A fluorescence probe, 8-formyl-7-hydroxyl-4-methyl coumarin - (2?-methylquinoline-4-formyl) hydrazone (L) has been synthesized. The chemosensor is found preferential binding to Al3+ in presence of other competitive ions with associated changes in its optical and fluorescence spectra behavior. Upon addition of Al3+ to a solution of L, it shows 200-fold enhancement of fluorescence intensity which might be attributed to form a 2:1 stoichiometry of the binding mode of Lsbnd Al(III) and the chelation enhanced fluorescence (CHEF) process at 479 nm in ethanol. The lowest detection limit for Al3+ is determined as 8.2 × 10-7 M.

  1. Detection of Fingerprints Based on Elemental Composition Using Micro-X-Ray Fluorescence.

    SciTech Connect

    Worley, C. G. (Christopher G.); Wiltshire, S. (Sara); Miller, T. C. (Thomasin C.); Havrilla, G. J. (George J.); Majidi, V. (Vahid)

    2005-01-01

    A method was developed to detect fingerprints using a technique known as micro-X-ray fluorescence. The traditional method of detecting fingerprints involves treating the sample with certain powders, liquids, or vapors to add color to the fingerprint so that it can be easily seen and photographed for forensic purposes. This is known as contrast enhancement, and a multitude of chemical processing methods have been developed in the past century to render fingerprints visible. However, fingerprints present on certain substances such as fibrous papers and textiles, wood, leather, plastic, adhesives, and human skin can sometimes be difficult to detect by contrast enhancement. Children's fingerprints are also difficult to detect due to the absence of sebum on their skin, and detection of prints left on certain colored backgrounds can sometimes be problematic. Micro-X-ray fluorescence (MXRF) was studied here as a method to detect fingerprints based on chemical elements present in fingerprint residue. For example, salts such as sodium chloride and potassium chloride excreted in sweat are sometimes present in detectable quantities in fingerprints. We demonstrated that MXRF can be used to detect this sodium, potassium, and chlorine from such salts. Furthermore, using MXRF, each of these elements (and many other elements if present) can be detected as a function of location on a surface, so we were able to 'see' a fingerprint because these salts are deposited mainly along the patterns present in a fingerprint (traditionally called friction ridges in forensic science). MXRF is not a panacea for detecting all fingerprints; some prints will not contain enough detectable material to be 'seen'; however, determining an effective means of coloring a fingerprint with traditional contrast enhancement methods can sometimes be an arduous process with limited success. Thus, MXRF offers a possible alternative for detecting fingerprints, and it does not require any additional chemical treatment steps which can be time consuming and permanently alter the sample. Additionally, MXRF is noninvasive, so a fingerprint analyzed by this method is left pristine for examination by other methods (eg. DNA extraction). To the best of the author's knowledge, no studies have been published to date concerning the detection of fingerprints by micro-X-ray fluorescence. Some studies have been published in which other spectroscopic methods were employed to examine the chemical composition of fingerprints (eg. IR, SEM/EDX, and Auger), but very few papers discuss the actual detection and imaging of a complete fingerprint by any spectroscopic method. Thus, this work is unique.

  2. Simple and rapid HPLC method for determination of amlodipine in human serum with fluorescence detection and its use in pharmacokinetic studies

    Microsoft Academic Search

    Gh Bahrami; Sh Mirzaeei

    2004-01-01

    A fast, sensitive and specific high performance liquid chromatographic method using fluorescence detection is described for analysis of amlodipine in human serum. Amlodipine is extracted from serum by ethyl acetate and involves precolumn derivatization with 4-chloro-7-nitrobenzofurazan (NBD-Cl) and reverse-phase chromatography on C18 column. The mobile phase was sodium phosphate buffer (pH 2.5) containing 1ml\\/l triethylamine and methanol at flow rate

  3. Automatic analyzer for highly polar carboxylic acids based on fluorescence derivatization-liquid chromatography.

    PubMed

    Todoroki, Kenichiro; Nakano, Tatsuki; Ishii, Yasuhiro; Goto, Kanoko; Tomita, Ryoko; Fujioka, Toshihiro; Min, Jun Zhe; Inoue, Koichi; Toyo'oka, Toshimasa

    2015-03-01

    A sensitive, versatile, and reproducible automatic analyzer for highly polar carboxylic acids based on a fluorescence derivatization-liquid chromatography (LC) method was developed. In this method, carboxylic acids were automatically and fluorescently derivatized with 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride by adopting a pretreatment program installed in an LC autosampler. All of the DBD-PZ-carboxylic acid derivatives were separated on the ODS column within 30 min by gradient elution. The peak of DBD-PZ did not interfere with the separation and the quantification of all the acids with the exception of lactic acid. From the LC-MS/MS analysis, we confirmed that lactic acid was converted to an oxytriazinyl derivative, which was further modified with a dimethoxy triazine group of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). We detected this oxytriazinyl derivative to quantify lactic acid. The detection limits (signal-to-noise ratio = 3) for the examined acids ranged from 0.19 to 1.1 µm, which correspond to 95-550 fmol per injection. The intra- and inter-day precisions of typical, highly polar carboxylic acids were all <9.0%. The developed method was successfully applied to the comprehensive analysis of carboxylic acids in various samples, which included fruit juices, red wine and media from cultured tumor cells. PMID:25082081

  4. Highly sensitive and selective fluorescent detection of cerebral lead(II) based on graphene quantum dot conjugates.

    PubMed

    Qi, Yan-Xia; Zhang, Min; Fu, Qian-Qian; Liu, Ran; Shi, Guo-Yue

    2013-11-21

    A novel probe based on graphene quantum dot conjugates was developed for fluorescent detection of Pb(2+) (LOD: 9 pM) and furthermore for monitoring Pb(2+) in the striatum of rat, combined with microdialysis sampling in vivo. PMID:24091904

  5. Time-resolved fluorescence of 2-aminopurine as a probe of base flipping in M.HhaI–DNA complexes

    PubMed Central

    Neely, Robert K.; Daujotyte, Dalia; Grazulis, Saulius; Magennis, Steven W.; Dryden, David T. F.; Klimašauskas, Saulius; Jones, Anita C.

    2005-01-01

    DNA base flipping is an important mechanism in molecular enzymology, but its study is limited by the lack of an accessible and reliable diagnostic technique. A series of crystalline complexes of a DNA methyltransferase, M.HhaI, and its cognate DNA, in which a fluorescent nucleobase analogue, 2-aminopurine (AP), occupies defined positions with respect the target flipped base, have been prepared and their structures determined at higher than 2 ? resolution. From time-resolved fluorescence measurements of these single crystals, we have established that the fluorescence decay function of AP shows a pronounced, characteristic response to base flipping: the loss of the very short (?100 ps) decay component and the large increase in the amplitude of the long (?10 ns) component. When AP is positioned at sites other than the target site, this response is not seen. Most significantly, we have shown that the same clear response is apparent when M.HhaI complexes with DNA in solution, giving an unambiguous signal of base flipping. Analysis of the AP fluorescence decay function reveals conformational heterogeneity in the DNA–enzyme complexes that cannot be discerned from the present X-ray structures. PMID:16340006

  6. Phasor-based single-molecule fluorescence lifetime imaging using a wide-field photon-counting detector

    E-print Network

    Michalet, Xavier

    Phasor-based single-molecule fluorescence lifetime imaging using a wide- field photon in terms of signal level (and therefore limited frame rate). Recently, the phasor approach has been-molecule experiments. Here we discuss the advantages of combining phasor analysis with a new type of FLIM acquisition

  7. Development of a Cell-Based Fluorescence Resonance Energy Transfer Reporter for Bacillus anthracis Lethal Factor Protease

    SciTech Connect

    Kimura, R H; Steenblock, E R; Camarero, J A

    2007-03-22

    We report the construction of a cell-based fluorescent reporter for anthrax lethal factor (LF) protease activity using the principle of fluorescence resonance energy transfer (FRET). This was accomplished by engineering an Escherichia coli cell line to express a genetically encoded FRET reporter and LF protease. Both proteins were encoded in two different expression plasmids under the control of different tightly controlled inducible promoters. The FRET-based reporter was designed to contain a LF recognition sequence flanked by the FRET pair formed by CyPet and YPet fluorescent proteins. The length of the linker between both fluorescent proteins was optimized using a flexible peptide linker containing several Gly-Gly-Ser repeats. Our results indicate that this FRET-based LF reporter was readily expressed in E. coli cells showing high levels of FRET in vivo in the absence of LF. The FRET signal, however, decreased 5 times after inducing LF expression in the same cell. These results suggest that this cell-based LF FRET reporter may be used to screen genetically encoded libraries in vivo against LF.

  8. A turn-on fluorescence probe for imaging iodide in living cells based on an elimination reaction.

    PubMed

    Kong, Fanpeng; Meng, Xiaoyue; Chu, Ranran; Xu, Kehua; Tang, Bo

    2015-04-25

    Based on a unique elimination reaction prompted by the iodide ion, a novel turn-on fluorescence probe (HCy-OMe-Br) has been developed for the first time. The probe emits in the near infrared region with a large Stokes shift, and can respond rapidly to iodide with high selectivity and sensitivity. PMID:25794327

  9. Design and Field Testing of a Fiber Laser Based Formaldehyde Laser-Induced Fluorescence Instrument During BEARPEX 2009

    Microsoft Academic Search

    Joshua Digangi; Joshua Paul; Samuel Henry; Aster Kammrath; Frank Keutsch

    2010-01-01

    The oxidation of volatile organic compounds (VOCs) is central to the production of tropospheric ozone and the formation of secondary organic aerosol (SOA). Formaldehyde (HCHO) is one of the most ubiquitous VOC oxidation products and thus an important tracer of VOC oxidation. We have developed a laser-induced fluorescence (LIF) instrument for fast, high-sensitivity measurements of HCHO based on a novel

  10. Telegrapher-based fluorescence-enhanced optical tomography in small volume

    NASA Astrophysics Data System (ADS)

    Roy, Ranadhir

    2010-02-01

    Accurate modeling of photon propagation in small animals is critical to quantitatively obtain accurate tomographic images. The diffusion approximation is used for biomedical optical diagnostic techniques in turbid large media where absorption is low compared to scattering system. This approximation has considerable limitations to accurately predict radiative transport in turbid small media and also in a media where absorption is high compared to scattering systems. A radiative transport equation (RTE) is best suited for photon propagation in human tissues. However, such models are quite expensive computationally. To alleviate the problems of the high computational cost of RTE and inadequacies of the diffusion equation in a small volume, we use telegrapher equation (TE) in the frequency domain for fluorescence-enhanced optical tomography problems. The telegrapher equation can accurately and efficiently predict ballistic as well as diffusion-limited transport regimes which could simultaneously exist in small animals. The telegrapher-based model is tested by comparing with the diffusion-based model using stimulated data in a small volume. This work shows the telegrapher-based model is appropriate in small animal optical tomography problems.

  11. Development of Ta-based Superconducting Tunnel Junction X-ray Detectors for Fluorescence XAS

    SciTech Connect

    Friedrich, Stephan; Drury, Owen B. [Lawrence Livermore National Lab, Advanced Detector Group, 7000 East Ave., L-188, Livermore, CA 94550 (United States); Hall, John; Cantor, Robin [STAR Cryoelectronics, 25-A Bisbee Court, Santa Fe, NM 87508 (United States)

    2010-06-23

    We are developing superconducting tunnel junction (STJ) soft X-ray detectors for chemical analysis of dilute samples by fluorescence-detected X-ray absorption spectroscopy (XAS). Our 36-pixel Nb-based STJ spectrometer covers a solid angle {Omega}/4{pi}{approx_equal}10{sup -3}, offers an energy resolution of {approx}10-20 eV FWHM for energies up to {approx}1 keV, and can be operated at total count rates of {approx}10{sup 6} counts/s. For increased quantum efficiency and cleaner response function, we have now started the development of Ta-based STJ detector arrays. Initial devices modeled after our Nb-based STJs have an energy resolution below 10 eV FWHM for X-ray energies below 1 keV, and pulse rise time discrimination can be used to improve their response function for energies up to several keV. We discuss the performance of the Ta-STJs and outline steps towards the next-generation of large STJ detector arrays with higher sensitivity.

  12. Highly selective and sensitive fluorescence chemosensor for the detection of palladium species based on Tsuji-Trost reaction.

    PubMed

    Xu, Zhong-Yong; Li, Jing; Guan, Su; Zhang, Lei; Dong, Chang-Zhi

    2015-09-01

    A new chemosensor 7-nitro-2,1,3-benzoxadiazole-4-allyl-N-(thiophen-2-ylmethyl)carbamate (NBDTC) was synthesized and utilized for palladium detection based on the Tsuji-Trost reaction. NBDTC displayed specific and ratiometric fluorescent responses toward palladium species. The chemosensor showed more than 50-fold enhancement in fluorescence intensity with the presence of PEG400 and palladium because NBDTC can be transformed to NBDT under palladium-catalyzing Tsuji-Trost reaction. NBDTC displayed high selectivity and sensitivity for palladium species with the detection limit of 1.13×10(-9)M. PMID:25863454

  13. A new fluorescent probe for Al(3+) based on rhodamine 6G and its application to bioimaging.

    PubMed

    Fu, Yan; Jiang, Xiu-Juan; Zhu, Yan-Yan; Zhou, Bing-Jiang; Zang, Shuang-Quan; Tang, Ming-Sheng; Zhang, Hong-Yan; Mak, Thomas C W

    2014-09-01

    A water-soluble rhodamine-based derivative (L) has been rationally designed for selective recognition of Al(3+) in aqueous medium with good sensitivity. The addition of Al(3+) to the aqueous solution of L induces a remarkable fluorescence enhancement along with obvious color change detected by the naked eye, due to the ring-opening mechanism of the rhodamine spirolactam, which has been proved by single crystal diffraction analyses directly. The recognizing behavior has been investigated both experimentally and computationally. Furthermore, the fluorescent probe can also be used as a bioimaging reagent for detection of Al(3+) in living cells. PMID:25007919

  14. Enhancing analysis of cells and proteins by fluorescence imaging on silk-based biomaterials: modulating the autofluorescence of silk.

    PubMed

    Neo, Puay Yong; Tan, Daryl Jian-An; Shi, Pujiang; Toh, Siew Lok; Goh, James Cho-Hong

    2015-02-01

    Silk is a versatile and established biomaterial for various tissue engineering purposes. However, it also exhibits strong autofluorescence signals-thereby hindering fluorescence imaging analysis of cells and proteins on silk-derived biomaterials. Sudan Black B (SB) is a lysochrome dye commonly used to stain lipids in histology. It has also been reported to be able to quench autofluorescence of tissues in histology and has been tested on artificial biomedical polymers in recent years. It was hypothesized that SB would exert similar quenching effects on silk, modulating the autofluorescence signals, and thereby enabling improved imaging analysis of cells and molecules of interests. The quenching effect of SB on the intrinsic fluorescence properties of silk and on commercial fluorescent dyes were first investigated in this study. SB was then incorporated into typical fluorescence-based staining protocols to study its effectiveness in improving fluorescence-based imaging of the cells and proteins residing with the silk-based biomaterials. Silk processed into various forms of biomaterials (e.g., films, sponges, fibers, and electrospun mats) was seeded with cells and cultured in vitro. At sacrificial time points, specimens were harvested, fixed, and prepared for fluorescence staining. SB, available commercially as a powder, was dissolved in 70% ethanol (0.3% [w/v]) to form staining solutions. SB treatment was introduced at the last step of typical immunofluorescence staining protocols for 15-120?min. For actin staining protocols by phalloidin toxin, SB staining solutions were added before and after permeabilization with Triton-X for 15-30?min. Results showed that ideal SB treatment duration is about 15?min. Apart from being able to suppress the autofluorescence of silk, this treatment duration was also not too long to adversely affect the fluorescent labeling probes used. The relative improvement brought about by SB treatment was most evident in the blue and green emission wavelengths compared with the red emission wavelength. This study has showed that the use of SB is a cost and time effective approach to enhance fluorescence-based imaging analyses of cell-seeded silk biomaterials, which otherwise would have been hindered by the unmodulated autofluorescence signals. PMID:25050876

  15. Highly selective and sensitive fluorescence chemosensor for the detection of palladium species based on Tsuji-Trost reaction

    NASA Astrophysics Data System (ADS)

    Xu, Zhong-Yong; Li, Jing; Guan, Su; Zhang, Lei; Dong, Chang-Zhi

    2015-09-01

    A new chemosensor 7-nitro-2,1,3-benzoxadiazole-4-allyl-N-(thiophen-2-ylmethyl)carbamate (NBDTC) was synthesized and utilized for palladium detection based on the Tsuji-Trost reaction. NBDTC displayed specific and ratiometric fluorescent responses toward palladium species. The chemosensor showed more than 50-fold enhancement in fluorescence intensity with the presence of PEG400 and palladium because NBDTC can be transformed to NBDT under palladium-catalyzing Tsuji-Trost reaction. NBDTC displayed high selectivity and sensitivity for palladium species with the detection limit of 1.13 × 10-9 M.

  16. A Fluorescence-Quenching Platform based on Biomineralized Hydroxyapatite from Natural Seashell and Applied to Cancer Cell Detection

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Liu, Wei; Banks, Craig E.; Liu, Fei; Li, Mao; Xia, Fan; Yang, Xiangliang

    2014-12-01

    As a typical biomineral, hydroxyapatite (HAp) is widely applied in bone implants and other related fields. However, the inherent nature of HAp can potentially be altered through restricting its fabrication conditions. Here, HAp fabricated by a hydrothermal treatment of pieces of natural seashell is demonstrated to have the capability of fluorescence quenching. To the best of the author's knowledge, this is the first time that this new property of HAp has been reported. Consequently, we assembled a fluorescence-quenching platform based on the biomineralized HAp substrate following a hydrothermal treatment and associated with a DNA molecular beacon and applied to cancer cell detection by the transformation from ``OFF state'' (fluorescence quenching) to ``ON state'' (fluorescence recovery). Herein, we found that the outer surface of HAp material after hydrothermal biomineralization for 5 days has considerable capability for both fluorescence quenching and recovery. These results may also have implications in the further detection of various targets such as cancer cells with other special surface antigens, significant biological small molecules or disease related microRNA, just by changing the sequence of the nucleic acid beacon according to the corresponding aptamer.

  17. A highly selective fluorescent probe for sulfide ions based on aggregation of Cu nanocluster induced emission enhancement.

    PubMed

    Li, Zenghe; Guo, Song; Lu, Chao

    2015-04-21

    In this study, S(2-) ions were found to enhance the fluorescence of cysteine-capped Cu nanoclusters (Cu NCs). High resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy-energy dispersive X-ray (SEM-EDX) measurements, zeta potential and X-ray photoelectron spectroscopy (XPS) measurements demonstrated that the S(2-) ion-induced aggregation of the Cu NCs contributed to the fluorescence enhancement of the dispersed Cu NCs. Based on these findings, a highly selective fluorescent probe was developed for the determination of H2S using the S(2-) ion-enhanced fluorescence of the as-prepared Cu NCs. The relative fluorescence intensity was proportional to the concentration of S(2-) in the range from 0.2 to 50 ?M. The detection limit (S/N = 3) was 42 nM. The proposed method has been successfully applied to determine H2S produced from toys called "Fart Bomb" with recoveries of 97.6-101.8%. The results of the proposed method were in good agreement with those determined by a standard methylene blue method. This work is not only of importance for a better understanding of the aggregation induced emission (AIE) properties of the Cu NCs but also of great potential to find extensive biological applications for H2S. PMID:25697240

  18. High Power, Computer-Controlled, LED-Based Light Sources for Fluorescence Imaging and Image-Guided Surgery

    PubMed Central

    Gioux, Sylvain; Kianzad, Vida; Ciocan, Razvan; Gupta, Sunil; Oketokoun, Rafiou; Frangioni, John V.

    2009-01-01

    Optical imaging requires appropriate light sources. For image-guided surgery, and in particular fluorescence-guided surgery, high fluence rate, long working distance, computer control, and precise control of wavelength are required. In this study, we describe the development of light emitting diode (LED)-based light sources that meet these criteria. These light sources are enabled by a compact LED module that includes an integrated linear driver, heat-dissipation technology, and real-time temperature monitoring. Measuring only 27 mm W by 29 mm H, and weighing only 14.7 g, each module provides up to 6500 lx of white (400-650 nm) light and up to 157 mW of filtered fluorescence excitation light, while maintaining an operating temperature ? 50°C. We also describe software that can be used to design multi-module light housings, and an embedded processor that permits computer control and temperature monitoring. With these tools, we constructed a 76-module, sterilizable, 3-wavelength surgical light source capable of providing up to 40,000 lx of white light, 4.0 mW/cm2 of 670 nm near-infrared (NIR) fluorescence excitation light, and 14.0 mW/cm2 of 760 nm NIR fluorescence excitation light over a 15-cm diameter field-of-view. Using this light source, we demonstrate NIR fluorescence-guided surgery in a large animal model. PMID:19723473

  19. Injectable hydrogel microbeads for fluorescence-based in vivo continuous glucose monitoring

    PubMed Central

    Shibata, Hideaki; Heo, Yun Jung; Okitsu, Teru; Matsunaga, Yukiko; Kawanishi, Tetsuro; Takeuchi, Shoji

    2010-01-01

    Fluorescent microbeads hold great promise for in vivo continuous glucose monitoring with wireless transdermal transmission and long-lasting activity. The full potential of fluorescent microbeads has yet to be realized due to insufficient intensity for transdermal transmission and material toxicity. This paper illustrates the highly-sensitive, biostable, long-lasting, and injectable fluorescent microbeads for in vivo continuous glucose monitoring. We synthesized a fluorescent monomer composed of glucose-recognition sites, a fluorogenic site, spacers, and polymerization sites. The spacers are designed to be long and hydrophilic for increasing opportunities to bind glucose molecules; consequently, the fluorescent monomers enable high-intensive responsiveness to glucose. We then fabricated injectable-sized fluorescent polyacrylamide hydrogel beads with high uniformity and high throughput. We found that our fluorescent beads provide sufficient intensity to transdermally monitor glucose concentrations in vivo. The fluorescence intensity successfully traced the blood glucose concentration fluctuation, indicating our method has potential uses in highly-sensitive and minimally invasive continuous blood glucose monitoring. PMID:20921374

  20. Analysis of protein-based binding media found in paintings using laser induced fluorescence spectroscopy

    Microsoft Academic Search

    Austin Nevin; Sharon Cather; Demetrios Anglos; Costas Fotakis

    2006-01-01

    Laser induced fluorescence (LIF) spectroscopy of intrinsic fluorophores from organic media found in paintings (casein, animal glue and egg proteins) provides novel non-invasive means of characterisation of general classes of media on the basis of fluorescence emission arising from the presence of certain amino acids and their degradation byproducts. Proteins from traditionally employed binding media include collagen, casein, albumin and

  1. Wide and scalable field-of-view Talbot-grid-based fluorescence microscopy

    E-print Network

    Yang, Changhuei

    microscopy (FTM), which utilizes the Talbot self-imaging effect to enable efficient fluorescence imaging over a large and directly scalable FOV. The FTM prototype has a resolution of 1.2 m and an FOV of 3.9 mm × 3.5 mm. We demonstrate the imaging capability of FTM on fluorescently labeled breast cancer cells (SK

  2. New simple ESPI configurations for deformation studies on large structures based on diffused reference beam

    NASA Astrophysics Data System (ADS)

    Santhanakrishnan, T.; Krishna Mohan, Nandigana K.; Sirohi, Rajpal S.

    1996-07-01

    Two simple Electronic Speckle Pattern Interferometer (ESPI) configurations have been devised based on diffused reference beam which provides out-of-plane displacement data over the whole field. Both configurations use a tiny diffuser to generate the reference beam. This makes the system insensitive to reference beam misalignment, simplifies the construction of ESPI setup and allows larger area of observation unlike the conventional ESPI system. Thermal deflection studies on a cantilever plate have been carried out. Experimental results and features over the conventional ESPI system are discussed.

  3. Latest results of 5-ALA-based fluorescence diagnosis and other medical disciplines

    NASA Astrophysics Data System (ADS)

    Baumgartner, Reinhold

    1999-02-01

    Preclinical and clinical studies on 5-aminolevulinic acid (5- ALA) induced Protoporphyrin IX (PPIX) are performed in various departments now following promising clinical results for the detection of bladder cancer in urology. This paper provides an overview on the progress of 5-ALA assisted fluorescence diagnosis in urology, pulmonology, neurosurgery, gynecology and ENT coordinated by the Laser Research Laboratory of the Ludwig-Maximilians-University in Munich. 5-ALA can be applied either topically or systematically to induce an intracellular accumulation of fluorescing PPIX. With appropriate dosage of 5-ALA, malignant tissue can be stained selectively, and irradiation with violet light excites a bright red fluorescence of the tumor visible with naked eyes. Optical properties of the tissue tend to hamper the precise identification and demarcation of suspect areas in fluorescence images. Multicolor remission and fluorescence imaging, therefore, should improve tumor localization in future.

  4. Time-resolved two-photon excited fluorescence spectroscopy based on a streak camera

    NASA Astrophysics Data System (ADS)

    Liu, Lixin; Qu, Junle; Chen, Danni; Lin, Ziyang; Xu, Gaixia; Guo, Baoping; Niu, Hanben

    2006-09-01

    Combination of fluorescence spectral and temporal resolutions can improve the sensitivity and specificity of biomedical diagnostics. In this paper, we present the development of a time resolved two-photon excited fluorescence spectroscopy system that consists of a Ti: Sapphire femtosecond laser, a fluorescence microscope objective, a prism spectrophotometer and a high repetition rate picosecond streak camera. The streak camera and the time-resolved fluorescence spectroscopy system. have been calibrated with an F-P etalon and a spectral line lamp respectively. Validation experiment of the system is also performed on two standard fluorescent dyes (Rhodamine 6G and Coumarin 314), and the results agree well with those reported in the literatures. Preliminary experimental results on autofluorescence spectra and lifetimes of freshly picked leaves and in vivo human skin are also presented, which demonstrates the potential applications of this system in tissue discrimination and clinical diagnostics.

  5. Determination of proteins by fluorescence quenching of erythrosin B

    Microsoft Academic Search

    Chun Qi Ma; Ke An Li; Shen Yang Tong

    1996-01-01

    Erythrosin B (EB) binding to proteins causes a decrease in the fluorescence maximum of EB at 550 nm. Based on this, a new, fast and simple fluorescence quenching method for the determination of proteins is developed. The linear range of this assay is 1.36–20.4 ?g ml?1. The method has very few interferences, most of which can be minimized by dilution.

  6. Luminescent quantum dots fluorescence resonance energy transfer-based probes for enzymatic activity and enzyme inhibitors.

    PubMed

    Shi, Lifang; Rosenzweig, Nitsa; Rosenzweig, Zeev

    2007-01-01

    The paper describes the development and characterization of analytical properties of quantum dot-based probes for enzymatic activity and for screening enzyme inhibitors. The luminescent probes are based on fluorescence resonance energy transfer (FRET) between luminescent quantum dots that serve as donors and rhodamine acceptors that are immobilized to the surface of the quantum dots through peptide linkers. Peptide-coated CdSe/ZnS quantum dots were prepared using a one-step ligand exchange process in which RGDC peptide molecules replace trioctylphosphine oxide (TOPO) molecules as the capping ligands of the quantum dots. The peptide molecules were bound to the surface of the CdSe/ZnS quantum dots through the thiol group of the peptide cysteine residue. The peptide-coated quantum dots were labeled with rhodamine to form the FRET probes. The emission quantum yield of the quantum dot FRET probes was 4-fold lower than the emission quantum yield of TOPO-capped quantum dots. However, the quantum dot FRET probes were sufficiently bright to enable quantitative enzyme and enzyme inhibition assays. The probes were used first to test the enzymatic activity of trypsin in solution based on FRET signal changes of the quantum dot-based enzymatic probes in the presence of proteolytic enzymes. For example, exposure of the quantum dot FRET probes to 500 microg/mL trypsin for 15 min resulted in 60% increase in the photoluminescence of the quantum dots and a corresponding decrease in the emission of the rhodamine molecules. These changes resulted from the release of rhodamine molecules from the surface of the quantum dots due to enzymatic cleavage of the peptide molecules. The quantum dot FRET-based probes were used to monitor the enzymatic activity of trypsin and to screen trypsin inhibitors for their inhibition efficiency. PMID:17194141

  7. A Non-Templated Approach for Tuning the Spectral Properties of cyanine-based Fluorescent NanoGUMBOS

    PubMed Central

    Das, Susmita; Bwambok, David; El-Zahab, Bilal; Monk, Joshua; de Rooy, Sergio L; Challa, Santhosh; Li, Min; Hung, Francisco R.; Baker, Gary A.; Warner, Isiah M

    2010-01-01

    Template free controlled aggregation and spectral properties in fluorescent organic nanoparticles (FONs) is highly desirable for various applications. Herein, we report a non-templated method for controlling the aggregation in NIR cyanine-based nanoparticles derived from a Group of Uniform Materials Based on Organic salts (GUMBOS). The cationic heptamethine cyanine dye, 1,1?,3,3,3?,3?-hexamethylindotricarbocyanine (HMT), was coupled with five different anions viz. [NTf2?], [BETI?], [TFPB], [AOT?] and [TFP4B] by ion exchange method to obtain the respective GUMBOS. The nanoGUMBOS obtained via a reprecipitation method were primarily amorphous and spherical (30-100 nm) as suggested by selected area electron diffraction (SAED) and transmission electron micrographs (TEM). The formation of tunable self-assemblies within the nanoGUMBOS was characterized using absorption and fluorescence spectroscopy, in conjunction with molecular dynamic simulations. Counterion controlled spectral properties observed in the nanoGUMBOS were attributed to variations in J/H ratios with different anions. Association with the anion [AOT?] afforded predominant J-aggregation enabling highest fluorescence intensity, while [TFP4B?] disabled the fluorescence due to predominant H-aggregation in the nanoparticles. Analyses of the stacking angle of the cations based on molecular dynamic simulation results in [HMT][NTf2], [HMT][BETI] and [HMT][AOT] dispersed in water and visual analysis of representative simulation snapshots also imply that the type of aggregation was controlled through the counterion associated with the dye cation. PMID:20583774

  8. RNA-Based Fluorescent Biosensors for Live Cell Imaging of Second Messenger Cyclic di-AMP.

    PubMed

    Kellenberger, Colleen A; Chen, Chen; Whiteley, Aaron T; Portnoy, Daniel A; Hammond, Ming C

    2015-05-27

    Cyclic di-AMP (cdiA) is a second messenger predicted to be widespread in Gram-positive bacteria, some Gram-negative bacteria, and Archaea. In the human pathogen Listeria monocytogenes, cdiA is an essential molecule that regulates metabolic function and cell wall homeostasis, and decreased levels of cdiA result in increased antibiotic susceptibility. We have generated fluorescent biosensors for cdiA through fusion of the Spinach2 aptamer to ligand-binding domains of cdiA riboswitches. The biosensor was used to visualize intracellular cdiA levels in live L. monocytogenes strains and to determine the catalytic domain of the phosphodiesterase PdeA. Furthermore, a flow cytometry assay based on this biosensor was used to screen for diadenylate cyclase activity and confirmed the enzymatic activity of DisA-like proteins from Clostridium difficile and Methanocaldococcus jannaschii. Thus, we have expanded the development of RNA-based biosensors for in vivo metabolite imaging in Gram-positive bacteria and have validated the first dinucleotide cyclase from Archaea. PMID:25965978

  9. Fluorescence-enhanced imaging using a novel hand-held based optical imager: phantom studies

    NASA Astrophysics Data System (ADS)

    Ge, Jiajia; Zhu, Banghe; Regalado, Steven; Godavarty, Anuradha

    2008-02-01

    Near-infrared (NIR) optical imaging is an emerging noninvasive modality for breast cancer diagnosis. The currently available optical imaging systems towards tomography studies are limited either by instrument portability, patient comfort, or flexibility to image any given tissue volume. Hence, a novel hand-held probe based gain modulated intensified CCD camera imaging system is developed such that it can possibly overcome some of the above limitations. The unique features of this hand-held probe based optical imaging system are: (i) to perform simultaneous multiple point illumination and detection, thus decreasing the total imaging time and improving overall signal strength; (ii) to adapt to the tissue contours, thus decreasing the light leakage at contact surface; and (iii) to obtain trans-illumination measurements apart from reflectance measurements, thus improving the depth information. Phantom studies are performed to demonstrate the feasibility of performing fluorescence optical imaging under different target depths using cubical phantoms (10×6.5×10 cc). The effect of simultaneous multiple point illumination over sequential single point illumination is demonstrated from experimental phantom studies.

  10. Microfluidic-based metal enhanced fluorescence for capillary electrophoresis by Ag nanorod arrays

    NASA Astrophysics Data System (ADS)

    Xiao, Chenyu; Cao, Zhen; Deng, Junhong; Huang, Zhifeng; Xu, Zheng; Fu, Junxue; Yobas, Levent

    2014-06-01

    As metal nanorods show much higher metal enhanced fluorescence (MEF) than metal nanospheres, microfluidic-based MEF is first explored with Ag nanorod (ND) arrays made by oblique angle deposition. By measuring the fluorescein isothiocyanate (FITC) solution sandwiched between the Ag NDs and a piece of cover slip, the enhancement factors (EFs) are found as 3.7 ± 0.64 and 6.74 ± 2.04, for a solution thickness at 20.8 ?m and 10 ?m, respectively. Because of the strong plasmonic coupling between the adjacent Ag NDs, only the emission of the fluorophores present in the three-dimensional NDs array gets enhanced. Thus, the corresponding effective enhancement factors (EEFs) are revealed to be relatively close, 259 ± 92 and 340 ± 102, respectively. To demonstrate the application of MEF in microfluidic systems, a multilayer of SiO2 NDs/Ag NDs is integrated with a capillary electrophoresis device. At a microchannel depth of 10 ?m, an enhancement of 6.5 fold is obtained for amino acids separation detection. These results are very encouraging and open the possibility of MEF applications for the Ag ND arrays decorated microchannels. With the miniaturization of microfluidic devices, microfluidic-based MEF by Ag ND arrays will likely find more applications with further enhancement.

  11. Development of a Fluorescent Quenching Based High Throughput Assay to Screen for Calcineurin Inhibitors

    PubMed Central

    Mukherjee, Abhisek; Syeb, Kathleen; Concannon, John; Callegari, Keri; Soto, Claudio; Glicksman, Marcie A.

    2015-01-01

    Currently there is no effective treatment available for major neurodegenerative disorders associated to protein misfolding, including Alzheimer’s and Parkinson's disease. One of most promising therapeutic approaches under development focuses on inhibiting the misfolding and aggregation pathway. However, it is likely that by the time clinical symptoms appear, there is a large accumulation of misfolded aggregates and a very substantial damage to the brain. Thus, it seems that at the clinical stage of the disease it is necessary also to develop strategies aiming to prevent the neuronal damage produced by already formed misfolded aggregates. Chronic activation of calcineurin (CaN), a type IIB phosphatase, has been implicated as a pivotal molecule connecting synaptic loss and neuronal damage to protein misfolding. The fact that the crystal structure of CaN is also well established makes it an ideal target for drug discovery. CaN activity assays for High Throughput Screening (HTS) reported so far are based on absorbance. In this article we report the development of a fluorescent quenching based CaN activity assay suitable for robotic screening of large chemical libraries to find novel inhibitors. The assay yielded a Z score of 0.84 with coefficient of variance ? 15%. Our results also show that this assay can be used to identify CaN inhibitors with a wide range of potencies. PMID:26176772

  12. Cell-based fluorescence assay for evaluation of new-drugs potential for phospholipidosis in an early stage of drug development

    Microsoft Academic Search

    Hisako Fujimura; Eriha Dekura; Michie Kurabe; Noriko Shimazu; Mieko Koitabashi; Wataru Toriumi

    2007-01-01

    To evaluate new-drugs potential for phospholipidosis (PL), we developed a cell-based fluorescence assay using a fluorescent-labeled phospholipid analogue (NBD-PE). CHL\\/IU cells derived from newborn hamster lung were exposed to positive reference compounds (amiodarone, imipramine, chloroquine, propranolol, chlorpromazine and amantadine) in the presence of NBD-PE, and the level of PL, as indicated by accumulation of fluorescent inclusions in the cytoplasm, was

  13. Achieving high power efficiency and low roll-off OLEDs based on energy transfer from thermally activated delayed excitons to fluorescent dopants.

    PubMed

    Wang, Shipan; Zhang, Yuewei; Chen, Weiping; Wei, Jinbei; Liu, Yu; Wang, Yue

    2015-07-14

    Achieving high power efficiencies at high-brightness levels is still an important issue for organic light-emitting diodes (OLEDs) based on the thermally activated delayed fluorescence (TADF) mechanism. Herein, enhanced electroluminescence efficiencies were achieved in fluorescent OLEDs using a TADF molecule, (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN), as a host and quinacridone derivatives (QA) as fluorescent dopants. PMID:26120606

  14. Fluorescence-based high-throughput functional profiling of ligand-gated ion channels at the level of single cells.

    PubMed

    Talwar, Sahil; Lynch, Joseph W; Gilbert, Daniel F

    2013-01-01

    Ion channels are involved in many physiological processes and are attractive targets for therapeutic intervention. Their functional properties vary according to their subunit composition, which in turn varies in a developmental and tissue-specific manner and as a consequence of pathophysiological events. Understanding this diversity requires functional analysis of ion channel properties in large numbers of individual cells. Functional characterisation of ligand-gated channels involves quantitating agonist and drug dose-response relationships using electrophysiological or fluorescence-based techniques. Electrophysiology is limited by low throughput and high-throughput fluorescence-based functional evaluation generally does not enable the characterization of the functional properties of each individual cell. Here we describe a fluorescence-based assay that characterizes functional channel properties at single cell resolution in high throughput mode. It is based on progressive receptor activation and iterative fluorescence imaging and delivers >100 dose-responses in a single well of a 384-well plate, using ?1-3 homomeric and ?? heteromeric glycine receptor (GlyR) chloride channels as a model system. We applied this assay with transiently transfected HEK293 cells co-expressing halide-sensitive yellow fluorescent protein and different GlyR subunit combinations. Glycine EC50 values of different GlyR isoforms were highly correlated with published electrophysiological data and confirm previously reported pharmacological profiles for the GlyR inhibitors, picrotoxin, strychnine and lindane. We show that inter and intra well variability is low and that clustering of functional phenotypes permits identification of drugs with subunit-specific pharmacological profiles. As this method dramatically improves the efficiency with which ion channel populations can be characterized in the context of cellular heterogeneity, it should facilitate systems-level analysis of ion channel properties in health and disease and the discovery of therapeutics to reverse pathological alterations. PMID:23520514

  15. X-ray absorption spectroscopy: A fluorescence detection system based on a plastic scintillator

    NASA Astrophysics Data System (ADS)

    Tourillon, G.; Guay, D.; Lemonnier, M.; Bartol, F.; Badeyan, M.

    1990-09-01

    A fluorescence detection system based on a plastic scintillator is presented that can be used for both X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) spectroscopy. Its counting rate is limited by the pulsation frequency of the synchrotron radiation (3.16×10 6 counts s -1), and can be theoretically extended to roughly 5×10 7 counts s -1 if used on a multibunch storage ring synchrotron radiation source. Its physical characteristics (fluorescence decay time and fast electronics) are such that the dead-time correction is entirely defined by the revolution period of the charged particles in the storage ring. It shows a broad spectral response and is particularly well adapted to the measurement of hard X-rays (from 6 to 25 keV). Its volume is small (diameter 60 mm; height 240 mm), and filters of small dimensions are used to preferentially remove the scattered radiation. The entrance window of the detector is placed at 2-3 mm above the top of the sample, and a solid angle of collection of nearly 50% of 2? sr is achieved. The shape of the plastic scintillator can be easily modified to fit various geometries. It operates in both horizontal and vertical planes. It is about ten times less expensive than an energy-dispersive detection system based on a single Ge solid-state detector. The detector presents a high sensitivity. It is possible to obtain the entire EXAFS spectrum of an electrochemically (under potential deposition) deposited monolayer of Cu atoms on gold, with acquisition time of less than one hour (compared to 25 h for a Ge solid-state detector). Orientation-dependent X-ray absorption spectroscopy was performed on thin (800 Å) copper phthalocyanine film, and the spectra of diluted Cu 2+ ions in aqueous solution (18 ppm) and Co atoms in YBa 2Cu 3O 7 powder (230 ppm) were also measured to assess the sensitivity of the detector.

  16. A new infeasible interior-point algorithm with full step for linear optimization based on a simple function

    Microsoft Academic Search

    Lipu Zhang; Yinghong Xu

    2011-01-01

    In this paper, we design and analyse an infeasible interior-point algorithm based on a simple function for linear optimization. The infeasible algorithm contains two types of search directions: the feasibility search direction and the centrality search direction. Both of the directions are determined by the simple function. The algorithm uses full step, thus no need to perform the line-search procedure.

  17. Compression-based distance (CBD): a simple, rapid, and accurate method for microbiota composition comparison

    PubMed Central

    2013-01-01

    Background Perturbations in intestinal microbiota composition have been associated with a variety of gastrointestinal tract-related diseases. The alleviation of symptoms has been achieved using treatments that alter the gastrointestinal tract microbiota toward that of healthy individuals. Identifying differences in microbiota composition through the use of 16S rRNA gene hypervariable tag sequencing has profound health implications. Current computational methods for comparing microbial communities are usually based on multiple alignments and phylogenetic inference, making them time consuming and requiring exceptional expertise and computational resources. As sequencing data rapidly grows in size, simpler analysis methods are needed to meet the growing computational burdens of microbiota comparisons. Thus, we have developed a simple, rapid, and accurate method, independent of multiple alignments and phylogenetic inference, to support microbiota comparisons. Results We create a metric, called compression-based distance (CBD) for quantifying the degree of similarity between microbial communities. CBD uses the repetitive nature of hypervariable tag datasets and well-established compression algorithms to approximate the total information shared between two datasets. Three published microbiota datasets were used as test cases for CBD as an applicable tool. Our study revealed that CBD recaptured 100% of the statistically significant conclusions reported in the previous studies, while achieving a decrease in computational time required when compared to similar tools without expert user intervention. Conclusion CBD provides a simple, rapid, and accurate method for assessing distances between gastrointestinal tract microbiota 16S hypervariable tag datasets. PMID:23617892

  18. [Molecular bases of the fluorescence method in the determination of binding capacity of serum albumin].

    PubMed

    Miller, Iu I; Dobretsov, G E

    1994-01-01

    A fluorescent method for assessment of albumin capacity to bind low-molecular metabolites, toxins, or drugs in blood serum, making use of fluorescent probe K-35, was recently suggested. The paper presents results of investigation of molecular basis of the method and of principles of interaction between fluorescent test molecules with albumin molecules in the blood serum. Molecules of fluorescent probe K-35 in blood serum plasma or serum are binding to albumin centers transporting low-molecular ligands (metabolites, toxins, drugs, etc.). Virtually the total intensity of K-35 fluorescence is due to the very molecules of the probe which are situated in these albumin centers. K-35 occupies two types of albumin centers, both of them equally contributing to total fluorescence intensity. Appearance of metabolites filling albumin centers and competing with K-35 probe results in reduction of the probe fluorescence. It is observed both in simulation experiments and in disease. It is possible that, besides the competitive mechanism, other mechanisms of blocking albumin centers in disease exist, to which K-35 is similarly sensitive. K-35 probe may be also used to measure effective albumin concentration. PMID:7850229

  19. A simple system for the identification of fluorescent dyes capable of reporting differences in secondary structure and hydrophobicity among amyloidogenic protein oligomers

    NASA Astrophysics Data System (ADS)

    Yates, Emma

    2012-02-01

    Thioflavin T and Congo Red are fluorescent dyes that are commonly used to identify the presence of amyloid structures, ordered protein aggregates. Despite the ubiquity of their use, little is known about their mechanism of interaction with amyloid fibrils, or whether other dyes, whose photophysics indicate that they may be more responsive to differences in macromolecular secondary structure and hydrophobicity, would be better suited to the identification of pathologically relevant oligomeric species in amyloid diseases. In order to systematically address this question, we have designed a strategy that discretely introduces differences in secondary structure and hydrophobicity amidst otherwise identical polyamino acids. This strategy will enable us to quantify and compare the affinities of Thioflavin T, Congo Red, and other, incompletely explored, fluorescent dyes for different secondary structural elements and hydrophobic motifs. With this information, we will identify dyes that give the most robust and quantitative information about structural differences among the complex population of oligomeric species present along an aggregation pathway between soluble monomers and amyloid fibrils, and correlate the resulting structural information with differential oligomeric toxicity.

  20. Simple methods of exploiting the underlying structure of rule-based systems

    NASA Technical Reports Server (NTRS)

    Hendler, James

    1986-01-01

    Much recent work in the field of expert systems research has aimed at exploiting the underlying structures of the rule base for reasons of analysis. Such techniques as Petri-nets and GAGs have been proposed as representational structures that will allow complete analysis. Much has been made of proving isomorphisms between the rule bases and the mechanisms, and in examining the theoretical power of this analysis. In this paper we describe some early work in a new system which has much simpler (and thus, one hopes, more easily achieved) aims and less formality. The technique being examined is a very simple one: OPS5 programs are analyzed in a purely syntactic way and a FSA description is generated. In this paper we describe the technique and some user interface tools which exploit this structure.

  1. Simple, filter-based PCR detection of Thelohania solenopsae (Microspora) in fire ants (Solenopsis invicta).

    PubMed

    Snowden, Karen F; Logan, Kathleen S; Vinson, S Bradleigh

    2002-01-01

    Thelohania solenopsae is a microsporidian parasite that may serve as a biological control agent for the red imported fire ant, Solenopsis invicta. A rapid, filter-based PCR amplification method detecting a portion of the small-subunit ribosomal RNA gene was developed to facilitate field studies detecting the parasite in fire ants. Processing ant homogenates with a commercially available membrane-based system, FTA Classic Card technology, compared favorably with traditional DNA extraction and PCR amplification methods. As few as 100 spores were detected. The FTA membrane system is a simple, extraction-free method for detecting T. solenopsae in fire ants, and allows for easy archival storage of DNA samples. PMID:12503678

  2. A simple spectrophotometric method for determination of zirconium or hafnium in selected molybdenum-base alloys

    NASA Technical Reports Server (NTRS)

    Dupraw, W. A.

    1972-01-01

    A simple analytical procedure is described for accurately and precisely determining the zirconium or hafnium content of molybdenum-base alloys. The procedure is based on the reaction of the reagent Arsenazo III with zirconium or hafnium in strong hydrochloric acid solution. The colored complexes of zirconium or hafnium are formed in the presence of molybdenum. Titanium or rhenium in the alloy have no adverse effect on the zirconium or hafnium complex at the following levels in the selected aliquot: Mo, 10 mg; Re, 10 mg; Ti, 1 mg. The spectrophotometric measurement of the zirconium or hafnium complex is accomplished without prior separation with a relative standard deviation of 1.3 to 2.7 percent.

  3. Coumarin-Based Turn-On Fluorescence Probe for Specific Detection of Glutathione over Cysteine and Homocysteine.

    PubMed

    He, Longwei; Xu, Qiuyan; Liu, Yong; Wei, Haipeng; Tang, Yonghe; Lin, Weiying

    2015-06-17

    We have prepared a turn-on fluorescent probe for biothiols based on bromoketo coumarin (KC-Br). The emission intensity of the coumarin chromophore is modulated by both the heavy atom effect and internal charge transfer (ICT) process. The probe KC-Br is intrinsically nonfluorescent; however, after being reacted with thiols, the bromide moiety is substituted by the -SH group, which elicits a significant fluorescence increase. We surmised the free -NH2 group would further react with carbonyl in the Cys/Hcy-substituted intermediate product yielding to Schiff base compound KC-Cys/KC-Hcy, but not in compound KC-GSH. The ICT effect has a stronger influence in compound KC-GSH than that in compound KC-Cys/KC-Hcy, resulting in compound KC-GSH having a stronger fluorescence. Thus, the probe has a good selectivity for GSH over other various biologically relevant species and even two other similar biothiols (Cys/Hcy) and could image glutathione (GSH) in living cells. We expect the design concept presented in this work would be widely used for the design of fluorescent probes for distinguishing among biothiols. PMID:26016515

  4. Up-conversion fluorescence "off-on" switch based on heterogeneous core-satellite assembly for thrombin detection.

    PubMed

    Zhao, Xueli; Li, Si; Xu, Liguang; Ma, Wei; Wu, Xiaoling; Kuang, Hua; Wang, Libing; Xu, Chuanlai

    2015-08-15

    NaGdF4: Yb, Er nanoparticles, with up-conversion (UC) fluorescence, were used for the first time to build an "off-on" switch based on Au core-UC satellites for thrombin detection. We fabricated the fluorescence sensor using thrombin aptamer modified Au core and complementary sequence modified UC satellites in liquid phase. With optimized assembled conditions, the yield of Au core-UC satellites achieved 80%. The fluorescence of UC nanoparticles quenched when satellite NP attached to Au core NP. Thrombin aptamer on the surface of Au core would bind to targets when thrombin existed in the system, then UC satellites were released and the quenched fluorescence recovered. The sensor showed high specificity for thrombin compared with other biomolecules and the limit of detection reached 3.5fg/mL. Application of this sensor to detect targets in human serum also achieved satisfactory results. The purpose of this work was to build an ultrasensitive sensor based on Au core-UC satellites for thrombin detection in human serum to achieve diagnosis of diseases. PMID:25845329

  5. Gold nanocluster-based fluorescent probes for near-infrared and turn-on sensing of glutathione in living cells.

    PubMed

    Tian, Dahui; Qian, Zhangsheng; Xia, Yunsheng; Zhu, Changqing

    2012-02-28

    In this study, a novel Au nanocluster (NC)-based fluorescent sensor has been designed for near-infrared (NIR) and turn-on sensing of glutathione (GSH) in both living cells and human blood samples. The large Stokes-shifted (140 nm) fluorescent Au NCs with NIR emission and long-wavelength excitation have been rapidly synthesized for 2 h by means of a microwave-assisted method in aqueous solution. The addition of Hg(II) leads to an almost complete emission quenching (98%) of Au NCs because of the interaction of Hg(II) and Au(I) on the surface of Au NCs. After introducing GSH to the Au NC-Hg(II) system, a more than 20 times fluorescent enhancement is obtained because of the preferable affinity of GSH with Hg(II). Under optimum conditions, the fluorescence recovery is linearly proportional to the concentration of GSH between 0.04 and 16.0 ?M and the detection limit is as low as 7.0 nM. This Au NC-based sensor with high sensitivity and low spectral interference has been proven to facilitate biosensing applications. PMID:22303958

  6. Community-Based Prevention Using Simple, Low-Cost, Evidence-Based Kernels and Behavior Vaccines

    ERIC Educational Resources Information Center

    Embry, Dennis D.

    2004-01-01

    A paradox exists in community prevention of violence and drugs. Good research now exists on evidence-based programs, yet extensive expenditures on prevention have not produced community-level results. Various multiproblems are quite prevalent in the United States, such as violence, Attention Deficit Hyperactivity Disorder (ADHD), conduct problems,…

  7. Simple, state-based approaches to program-based anomaly detection

    Microsoft Academic Search

    Christoph C. Michael; Anup K. Ghosh

    2002-01-01

    This article describes variants of two state-based intrusion detection algorithms from Michael and Ghosh [2000] and Ghosh et al. [2000], and gives experimental results on their performance. The algorithms detect anomalies in execution audit data. One is a simply constructed finite-state machine, and the other two monitor statistical deviations from normal program behavior. The performance of these algorithms is evaluated

  8. Novel anthracene-based fluorescent sensor for selective recognition of acetate anions in protic media

    NASA Astrophysics Data System (ADS)

    Xu, Kuoxi; Kong, Huajie; Li, Qian; Song, Pan; Dai, Yanpeng; Yang, Li

    2015-02-01

    Novel 9-substituted anthracene derivatives were synthesized and characterized by IR, HRMS, 1H and 13C NMR. The fluorescence titration experiments were explored to study the interaction between the compounds and some anions, such as H2PO4-, P2O74-, F-, Cl-, Br-, I-, AcO- in H2O (0.01 M HEPES, pH = 7.4) under imitated physiological conditions. One of these compounds, bearing a phenylalaninol unit, showed specific fluorescence enhancement with acetate anion. The sensor L1 was found to present good selective fluorescence sensing ability to acetate anion through photoinduced electron-transfer mechanism in protic media.

  9. A new fluorescent chemosensor for copper ions based on tripeptide glycyl-histidyl-lysine (GHK).

    PubMed

    Zheng, Y; Huo, Q; Kele, P; Andreopoulos, F M; Pham, S M; Leblanc, R M

    2001-10-18

    [structure: see text]. A new fluorescent chemosensor for Cu2+ ions was synthesized by modifying the tripeptide glycyl-histidyl-lysine (GHK) with 9-carbonylanthracene via the standard Fmoc solid-phase peptide synthesis method. While significant fluorescence quenching was observed from the molecule upon binding with Cu2+, addition of Fe2+, Co2+, Ni2+, and Zn2+ to the peptide solution caused a minimum fluorescence emission spectral change, indicating a high specificity of this chemosensor for Cu2+ ions. Effects of pH were also investigated. PMID:11594813

  10. Pencil-drawn paper supported electrodes as simple electrochemical detectors for paper-based fluidic devices.

    PubMed

    Dossi, Nicolò; Toniolo, Rosanna; Pizzariello, Andrea; Impellizzieri, Flavia; Piccin, Evandro; Bontempelli, Gino

    2013-07-01

    A simple procedure for preparing inexpensive paper-based three-electrode electrochemical cells is described here. They consist of small circular pads of hydrophilic paper defined by hydrophobic barriers printed on paper with wax-based ink. The back face of these pads is insulated by thermally laminating a polyethylene layer and working, reference and counter electrodes are drawn on paper by using commercial pencil leads. At last, a controlled volume of sample containing a supporting electrolyte was laid to soak in paper channels. Their performance was evaluated by assaying these devices as both simple cells suitable for recording voltammograms on static samples and low-cost detectors for flowing systems. Voltammetric tests, conducted by using potassium hexacyanoferrate(II) as model prototype, were also exploited for identifying the brand and softness of graphite sticks enabling paper to be marked with lines displaying the best conductivity. By taking advantage of the satisfactory information thus gained, pencil drawn electrodes were tested as amperometric detectors for the separation of ascorbic acid and sunset yellow, which were chosen as prototype electroactive analytes because they are frequently present concomitantly in several food matrices, such as soft drinks and fruit juices. This separation was performed by planar thin layer chromatography conducted on microfluidic paper-based devices prepared by patterning on filter paper two longitudinal hydrophobic barriers, once again printed with wax-based ink. Factors affecting both separation and electrochemical detection were examined and optimised, with best performance achieved by using a 20 mM acetate running buffer (pH 4.5) and by applying a detection potential of 0.9 V. Under these optimum conditions, the target analytes could be separated and detected within 6 min. The recorded peaks were well separated and characterized by good repeatability and fairly good sensitivity, thus proving that this approach is indeed suitable for rapidly assembling inexpensive and reliable electrochemical detectors for flow analysis systems. PMID:23161669

  11. A turn-on near-infrared fluorescent chemosensor for selective detection of lead ions based on a fluorophore-gold nanoparticle assembly.

    PubMed

    Wang, Shaozhen; Sun, Junyong; Gao, Feng

    2015-06-21

    A turn-on fluorescent chemosensor of Pb(2+) in the near-infrared (NIR) region, which is based on the Pb(2+)-tuned restored fluorescence of a weakly fluorescent fluorophore-gold nanoparticle (AuNPs) assembly, has been reported. In this fluorophore-AuNP assembly, NIR fluorescent dye brilliant cresyl blue (BCB) molecules act as fluorophores and are used for signal transduction of fluorescence, while AuNPs act as quenchers to quench the nearby fluorescent BCB molecules via electron transfer. In the presence of Pb(2+), fluorescent BCB molecules detached from AuNPs and restored their fluorescence due to the formation of a chelating complex between Pb(2+) and glutathione confined on AuNPs. Under the optimal conditions, the present BCB-AuNP assembly is capable of detecting Pb(2+) with a concentration ranging from 7.5 × 10(-10) to 1 × 10(-8) mol L(-1) (0.16-2.1 ng mL(-1)) and a detection limit of 0.51 nM (0.11 ng mL(-1)). The present BCB-AuNP assembly can be used in aqueous media for the determination of Pb(2+) unlike common organic fluorescent reagents, and also shows advantages of NIR fluorescence spectrophotometry such as less interference, lower detection limit, and higher sensitivity. Moreover, the present method was successfully applied for the detection of Pb(2+) in water samples with satisfactory results. PMID:25919909

  12. A Novel Fluorescence-based Genetic Strategy Identifies Mutants of Saccharomyces cerevisiae Defective for Nuclear Pore Complex Assembly

    PubMed Central

    Bucci, Mirella; Wente, Susan R.

    1998-01-01

    Nuclear pore complexes (NPCs) are large proteinaceous portals for exchanging macromolecules between the nucleus and the cytoplasm. Revealing how this transport apparatus is assembled will be critical for understanding the nuclear transport mechanism. To address this issue and to identify factors that regulate NPC formation and dynamics, a novel fluorescence-based strategy was used. This approach is based on the functional tagging of NPC proteins with the green fluorescent protein (GFP), and the hypothesis that NPC assembly mutants will have distinct GFP-NPC signals as compared with wild-type (wt) cells. By fluorescence-activated cell sorting for cells with low GFP signal from a population of mutagenized cells expressing GFP-Nup49p, three complementation groups were identified: two correspond to mutant nup120 and gle2 alleles that result in clusters of NPCs. Interestingly, a third group was a novel temperature-sensitive allele of nup57. The lowered GFP-Nup49p incorporation in the nup57-E17 cells resulted in a decreased fluorescence level, which was due in part to a sharply diminished interaction between the carboxy-terminal truncated nup57pE17 and wt Nup49p. Interestingly, the nup57-E17 mutant also affected the incorporation of a specific subset of other nucleoporins into the NPC. Decreased levels of NPC-associated Nsp1p and Nup116p were observed. In contrast, the localizations of Nic96p, Nup82p, Nup159p, Nup145p, and Pom152p were not markedly diminished. Coincidentally, nuclear import capacity was inhibited. Taken together, the identification of such mutants with specific perturbations of NPC structure validates this fluorescence-based strategy as a powerful approach for providing insight into the mechanism of NPC biogenesis. PMID:9725905

  13. Fluorescence-based recombination assay for sensitive and specific detection of genotoxic carcinogens in human cells.

    PubMed

    Ireno, Ivanildce C; Baumann, Cindy; Stöber, Regina; Hengstler, Jan G; Wiesmüller, Lisa

    2014-05-01

    In vitro genotoxicity tests are known to suffer from several shortcomings, mammalian cell-based assays, in particular, from low specificities. Following a novel concept of genotoxicity detection, we developed a fluorescence-based method in living human cells. The assay quantifies DNA recombination events triggered by DNA double-strand breaks and damage-induced replication fork stalling predicted to detect a broad spectrum of genotoxic modes of action. To maximize sensitivities, we engineered a DNA substrate encompassing a chemoresponsive element from the human genome. Using this substrate, we screened various human tumor and non-transformed cell types differing in the DNA damage response, which revealed that detection of genotoxic carcinogens was independent of the p53 status but abrogated by apoptosis. Cell types enabling robust and sensitive genotoxicity detection were selected for the generation of reporter clones with chromosomally integrated DNA recombination substrate. Reporter cell lines were scrutinized with 21 compounds, stratified into five sets according to the established categories for identification of carcinogenic compounds: genotoxic carcinogens ("true positives"), non-genotoxic carcinogens, compounds without genotoxic or carcinogenic effect ("true negatives") and non-carcinogenic compounds, which have been reported to induce chromosomal aberrations or mutations in mammalian cell-based assays ("false positives"). Our results document detection of genotoxic carcinogens in independent cell clones and at levels of cellular toxicities <60 % with a sensitivity of >85 %, specificity of ?90 % and detection of false-positive compounds <17 %. Importantly, through testing cyclophosphamide in combination with primary hepatocyte cultures, we additionally provide proof-of-concept for the identification of carcinogens requiring metabolic activation using this novel assay system. PMID:24671466

  14. Automatic choroid cells segmentation and counting based on approximate convexity and concavity of chain code in fluorescence microscopic image

    NASA Astrophysics Data System (ADS)

    Lu, Weihua; Chen, Xinjian; Zhu, Weifang; Yang, Lei; Cao, Zhaoyuan; Chen, Haoyu

    2015-03-01

    In this paper, we proposed a method based on the Freeman chain code to segment and count rhesus choroid-retinal vascular endothelial cells (RF/6A) automatically for fluorescence microscopy images. The proposed method consists of four main steps. First, a threshold filter and morphological transform were applied to reduce the noise. Second, the boundary information was used to generate the Freeman chain codes. Third, the concave points were found based on the relationship between the difference of the chain code and the curvature. Finally, cells segmentation and counting were completed based on the characteristics of the number of the concave points, the area and shape of the cells. The proposed method was tested on 100 fluorescence microscopic cell images, and the average true positive rate (TPR) is 98.13% and the average false positive rate (FPR) is 4.47%, respectively. The preliminary results showed the feasibility and efficiency of the proposed method.

  15. Exploring the possibility of early cataract diagnostics based on tryptophan fluorescence.

    PubMed

    Gakamsky, Dmitry M; Dhillon, Bal; Babraj, John; Shelton, Matthew; Smith, S Desmond

    2011-11-01

    A novel route for early cataract diagnostics is investigated based on the excitation of tryptophan fluorescence (TF) at the red edge of its absorption band at 317 nm. This allows penetration through the cornea and aqueous humour to provide excitation of the ocular lens. The steepness of the red edge gives the potential of depth control of the lens excitation. Such wavelength selection targets the population of tryptophan residues, side chains of which are exposed to the polar aqueous environment. The TF emissions around 350 nm of a series of UV-irradiated as well as control lenses were observed. TF spectra of the UV cases were red-shifted and the intensity decreased with the radiation dose. In contrast, intensity of non-tryptophan emission with maximum at 435 nm exhibited an increase suggesting photochemical conversion of the tryptophan population to 435 nm emitting molecules. We demonstrate that the ratio of intensities at 435 nm to that around 350 nm can be used as a measure of early structural changes caused by UV irradiation in the lens by comparison with images from a conventional slit-lamp, which can only detect defects of optical wavelength size. Such diagnostics at a molecular level could aid research on cataract risk investigation and possible pharmacological research as well as assisting surgical lens replacement decisions. PMID:21508010

  16. Fluorescence Imaging Enabled Urethane-Doped Citrate-Based Biodegradable Elastomers

    PubMed Central

    Zhang, Yi; Tran, Richard T.; Qattan, Ibrahim; Tsai, Yi-ting; Tang, Liping; Liu, Chao; Yang, Jian

    2013-01-01

    The field of tissue engineering and drug delivery calls for new measurement tools, non-invasive real-time assays, and design methods for the next wave of innovations. Based on our recent progress in developing intrinsically biodegradable photoluminescent polymers (BPLPs) without conjugating organic dyes or quantum dots, in this paper, we developed a new type urethane-doped biodegradable photoluminescent polymers (UBPLPs) that could potentially serve as a new tool to respond the above call for innovations. Inherited from BPLPs, UBPLPs demonstrated strong inherent photoluminescence and excellent cytocompatibility in vitro. Crosslinked UBPLPs (CUBPLPs) showed soft, elastic, but strong mechanical properties with a tensile strength as high as 49.41±6.17 MPa and a corresponding elongation at break of 334.87±26.31%. Porous triphasic CUBPLP vascular scaffolds showed a burst pressure of 769.33±70.88 mmHg and a suture retention strength of 1.79±0.11 N. Stable but photoluminescent nanoparticles with average size of 103 nm were also obtained by nanoprecipitation. High loading efficiency (91.84%) and sustained release of 5-fluorouracil (up to 120 h) were achieved from UBPLP nanoparticles. With a quantum yield as high as 38.65%, both triphasic scaffold and nanoparticle solutions could be non-invasively detected in vivo. UBPLPs represent an innovation in fluorescent biomaterial design and may offer great potential in advancing the field of tissue engineering and drug delivery where bioimaging has gained increasing interest. PMID:23465824

  17. Delivery and subcellular targeting of dendrimer-based fluorescent pH sensors in living cells.

    PubMed

    Albertazzi, Lorenzo; Storti, Barbara; Marchetti, Laura; Beltram, Fabio

    2010-12-29

    Synthesis and targeted delivery of dendrimer-based fluorescent biosensors in living HeLa cells are reported. Following electroporation dendrimers are shown to display specific subcellular localization depending on their size and surface charge and this property is preserved when they are functionalized with sensing moieties. We analyze the case of double dendrimer conjugation with pH-sensitive and pH-insensitive molecules leading to the realization of ratiometric pH sensors that are calibrated in vitro and in living cells. By tuning the physicochemical properties of the dendrimer scaffold sensors can be targeted to specific cellular compartments allowing selective pH measurements in different organelles in living cells. In order to demonstrate the modularity of this approach we present three different pH sensors with tuned H(+) affinity by appropriately choosing the pH-sensitive dye. We argue that the present methodology represents a general approach toward the realization of targetable ratiometric sensors suitable to monitor biologically relevant ions or molecules in living cells. PMID:21141854

  18. A Platform for Combined DNA and Protein Microarrays Based on Total Internal Reflection Fluorescence

    PubMed Central

    Asanov, Alexander; Zepeda, Angélica; Vaca, Luis

    2012-01-01

    We have developed a novel microarray technology based on total internal reflection fluorescence (TIRF) in combination with DNA and protein bioassays immobilized at the TIRF surface. Unlike conventional microarrays that exhibit reduced signal-to-background ratio, require several stages of incubation, rinsing and stringency control, and measure only end-point results, our TIRF microarray technology provides several orders of magnitude better signal-to-background ratio, performs analysis rapidly in one step, and measures the entire course of association and dissociation kinetics between target DNA and protein molecules and the bioassays. In many practical cases detection of only DNA or protein markers alone does not provide the necessary accuracy for diagnosing a disease or detecting a pathogen. Here we describe TIRF microarrays that detect DNA and protein markers simultaneously, which reduces the probabilities of false responses. Supersensitive and multiplexed TIRF DNA and protein microarray technology may provide a platform for accurate diagnosis or enhanced research studies. Our TIRF microarray system can be mounted on upright or inverted microscopes or interfaced directly with CCD cameras equipped with a single objective, facilitating the development of portable devices. As proof-of-concept we applied TIRF microarrays for detecting molecular markers from Bacillus anthracis, the pathogen responsible for anthrax. PMID:22438738

  19. Irradiation Induced Fluorescence Enhancement in PEGylated Cyanine-based NIR Nano- and Meso-scale GUMBOS

    PubMed Central

    Lu, Chengfei; Das, Susmita; Magut, Paul K. S.; Li, Min; El Zahab, Bilal; Warner, Isiah M.

    2014-01-01

    We report on the synthesis and characterization of a PEGylated IR786 GUMBOS (Group of Uniform Materials Based on Organic Salts). The synthesis of this material was accomplished using a three step protocol: (1) substitution of chloride on the cyclohexenyl ring in the heptamethine chain of IR786 by 6-aminohexanoic acid, (2) grafting of methoxy poly ethyleneglycol (MeOPEG) onto the 6-aminohexanoic acid via an esterification reaction, and (3) anion exchange between [PEG786][I] and lithium bis(trifluoromethylsulfonyl)imide (LiNTf2) or sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in order to obtain PEG786 GUMBOS. Examination of spectroscopic data for this PEG786 GUMBOS indicates a large stokes shift (122 nm). It was observed that this PEG786 GUMBOS associates in aqueous solution to form nano-and meso-scale self-assemblies with sizes ranging from 100 to 220 nm. These nano- and meso-scale GUMBOS are also able to resist nonspecific binding to proteins. PEGylation of the original IR786 leads to reduced cytotoxicity. In addition, it was noted that anions, such as NTf2 and AOT, play a significant role in improving the photostability of PEG786 GUMBOS. Irradiation-induced J aggregation in [PEG786][NTf2] and to some extent in [PEG786][AOT] produced enhanced photostability. This observation was supported by use of both steady state and time-resolved fluorescence measurements. PMID:22957476

  20. Irradiation induced fluorescence enhancement in PEGylated cyanine-based NIR nano- and mesoscale GUMBOS.

    PubMed

    Lu, Chengfei; Das, Susmita; Magut, Paul K S; Li, Min; El-Zahab, Bilal; Warner, Isiah M

    2012-10-01

    We report on the synthesis and characterization of a PEGylated IR786 GUMBOS (Group of Uniform Materials Based on Organic Salts). The synthesis of this material was accomplished using a three step protocol: (1) substitution of chloride on the cyclohexenyl ring in the heptamethine chain of IR786 by 6-aminohexanoic acid, (2) grafting of methoxy polyethylene glycol (MeOPEG) onto the 6-aminohexanoic acid via an esterification reaction, and (3) anion exchange between [PEG786][I] and lithium bis(trifluoromethylsulfonyl)imide (LiNTf(2)) or sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in order to obtain PEG786 GUMBOS. Examination of spectroscopic data for this PEG786 GUMBOS indicates a large stokes shift (122 nm). It was observed that this PEG786 GUMBOS associates in aqueous solution to form nano- and mesoscale self-assemblies with sizes ranging from 100 to 220 nm. These nano- and mesoscale GUMBOS are also able to resist nonspecific binding to proteins. PEGylation of the original IR786 leads to reduced cytotoxicity. In addition, it was noted that anions, such as NTf(2) and AOT, play a significant role in improving the photostability of PEG786 GUMBOS. Irradiation-induced J-aggregation in [PEG786][NTf(2)] and to some extent in [PEG786][AOT] produced enhanced photostability. This observation was supported by use of both steady state and time-resolved fluorescence measurements. PMID:22957476