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Sample records for simple fluorescence based

  1. Specific Fluorescence Probes for Lipid Droplets Based on Simple AIEgens.

    PubMed

    Wang, Zhiming; Gui, Chen; Zhao, Engui; Wang, Jing; Li, Xiaodong; Qin, Anjun; Zhao, Zujin; Yu, Zhenqiang; Tang, Ben Zhong

    2016-04-27

    Lipid droplets (LDs), as dynamic complex organelles, are involved in various physiological processes, and their numbers and activity are related to many diseases, even cancer. Hence, locating and concentration monitoring of LDs are very important to scientific bioresearch and health care. In this work, we prepared two simple luminogens (FAS and DPAS) via very facile synthetic procedures and purification. They feature aggregation-induced emission and excited state intramolecular proton transfer characteristics. They exhibit large Stokes shifts and bright orange and yellow emissions in the aggregated state, and the emissions can be reversibly turned "off" and "on" for many cycles by controlling buffer pH values. Both FAS and DPAS are cytocompatible and can selectively accumulate in and light up the LDs in living cells with superior resolution and high contrast. They also outperform the commercial LD probes in terms of photostability. Combining the advantages of high LD-specificity, good biocompatibility, surperb photostability, and low preparation cost, FAS and DPAS may become powerful tools to the study on LDs-related intracellular activities, such as LDs-based pathology and pharmacology. PMID:27053008

  2. A simple rhodamine hydrazide-based turn-on fluorescent probe for HOCl detection.

    PubMed

    Zhang, Zhen; Zou, Yuan; Deng, Chengquan; Meng, Liesu

    2016-06-01

    Hypochlorous acid (HOCl) plays a crucial role in daily life and mediates a variety of physiological processes, however, abnormal levels of HOCl have been associated with numerous human diseases. It is therefore of significant interest to establish a simple, selective, rapid and sensitive fluorogenic method for the detection of HOCl in environmental and biological samples. A hydrazide-containing fluorescent probe based on a rhodamine scaffold was facilely developed that could selectively detect HOCl over other biologically relevant reactive oxygen species, reactive nitrogen species and most common metal ions in vitro. Via an irreversible oxidation-hydrolysis mechanism, and upon HOCl-triggered opening of the intramolecular spirocyclic ring during detection, the rhodamine hydrazide-based probe exhibited large fluorescence enhancement in the emission spectra with a fast response, low detection limit and comparatively wide pH detection range in aqueous media. The probe was further successfully applied to monitoring trace HOCl in tap water and imaging both exogenous and endogenous HOCl within living cells. It is anticipated that this simple and useful probe might be an efficient tool with which to facilitate more HOCl-related chemical and biological research. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26663414

  3. A simple and sensitive label-free fluorescence sensing of heparin based on Cdte quantum dots.

    PubMed

    Rezaei, B; Shahshahanipour, M; Ensafi, Ali A

    2016-06-01

    A rapid, simple and sensitive label-free fluorescence method was developed for the determination of trace amounts of an important drug, heparin. This new method was based on water-soluble glutathione-capped CdTe quantum dots (CdTe QDs) as the luminescent probe. CdTe QDs were prepared according to the published protocol and the sizes of these nanoparticles were verified through transmission electron microscopy (TEM), X-ray diffraction (XRD) and dynamic light scattering (DLS) with an average particle size of about 7 nm. The fluorescence intensity of glutathione-capped CdTe QDs increased with increasing heparin concentration. These changes were followed as the analytical signal. Effective variables such as pH, QD concentration and incubation time were optimized. At the optimum conditions, with this optical method, heparin could be measured within the range 10.0-200.0 ng mL(-1) with a low limit of detection, 2.0 ng mL(-1) . The constructed fluorescence sensor was also applied successfully for the determination of heparin in human serum. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26542329

  4. 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

  5. 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

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

    PubMed

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

    2014-01-01

    A simple 4-hydroxynaphthalimide-derived colorimetric and ratiometric fluorescent probe (1) containing a receptor of levulinate moiety was designed and synthesized to monitor sulfite. Probe 1 could quantificationally detect sulfite by a ratiometric fluorescence spectroscopy method with high selectivity and sensitivity. Specially, probe 1 exhibited a 100 nm red-shifted absorption spectrum along with the color changes from colorless to yellow, and 103 nm red-shifted emission spectra upon the addition of sulfite. Thus, 1 can serve as a "naked-eye" probe for sulfite. Further, the recognition mechanism of probe 1 for sulfite was confirmed using nuclear magnetic resonance and electrospray ionization mass spectrometry. Also, the preliminary practical application demonstrated that our proposed probe provided a promising method for the determination of sulfite. PMID:24813958

  7. Simple Adhesive-Tape-Based Sampling of Tomato Surfaces Combined with Rapid Fluorescence In Situ Hybridization for Salmonella Detection▿

    PubMed Central

    Bisha, Bledar; Brehm-Stecher, Byron F.

    2009-01-01

    A simple adhesive-tape-based method for sampling of tomato surfaces was combined with fluorescence in situ hybridization for rapid culture-independent detection of Salmonella strains. Tapes could also be placed face-down on selective agar for on-tape enrichment of captured Salmonella cells. Overlay of cell-charged tapes with small volumes of liquid enrichment media enabled subsequent detection of tape-captured Salmonella via flow cytometry. PMID:19124588

  8. 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

  9. 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

  10. Dual-channel detection of Cu2+ and F- with a simple Schiff-based colorimetric and fluorescent sensor

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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 μM) of 1 for Cu2+ is much lower than that (30 μM) 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.

  11. A Simple Fluorescence Probe Based on Aggregation-Induced Emission (AIE) Property for the Detection of Mg(2+) Ions.

    PubMed

    Bian, Yan-Jiang; Wang, Lu-Qiong; Cao, Fu-Xiang; Tang, Li-Jun

    2016-01-01

    A simple aggregation-induced emission-based fluorescence probe (1) for Mg(2+) was synthesized by condensation of benzene-1, 2-diamine with 5-bromo-2-hydroxybenzaldehyde, This compound shows favourable character of the AIE-active molecules. More importantly, after addition of Mg(2+) to probe (1) in acetonitrile, the solution changed from colorless to yellow colour solution under ultraviolet (UV) radiation obtained from hand-held UV lamp, this finding suggested that probe (1) can be used to detect Mg(2+) by colorimetric detection. Detection limit can reach 2.31 × 10(-5) M(-1). The practical value of the selective and sensitive fluorescence indicators was confirmed by its application to detection of magnesium ion in acetonitrile. PMID:26547420

  12. Simple and sensitive fluorescent and electrochemical trinitrotoluene sensors based on aqueous carbon dots.

    PubMed

    Zhang, Lingling; Han, Yujie; Zhu, Jinbo; Zhai, Yanling; Dong, Shaojun

    2015-02-17

    Aqueous N-rich carbon dots (CDs), prepared by the microwave-assisted pyrolysis method, are applied as a dual sensing platform for both the fluorescent and electrochemical detection of 2,4,6-trinitrotoluene (TNT). The fluorescent sensing platform is established on the strong TNT-amino interaction which can quench the photoluminescence of amino functionalized CDs through charge transfer. The resultant linear detection ranges from 10 nM to 1.5 μM with a fast response time of 30 s. Glassy carbon electrode modified with CDs exhibits a fine capability for TNT reduction with the linear range from 5 nM to 30 μM, better than that obtained by the fluorescent method. Moreover, the minimum distinguishable response concentration with respect to these two methods is down to the nanomolar level with a high specificity and sensitivity. PMID:25600090

  13. Highly selective and simple method for determination of polythiols based on liquid chromatography with postcolumn excimer fluorescence derivatization.

    PubMed

    Yoshida, Hideyuki; Sudo, Maki; Todoroki, Kenichiro; Nohta, Hitoshi; Yamaguchi, Masatoshi

    2009-06-01

    An LC postcolumn derivatization method for determination of polythiols has been developed. This method involves separation using reversed-phase LC, postcolumn derivatization with N-(1-pyrenyl)maleimide, and excimer fluorescence detection. Analytes with a polythiol structure were converted into corresponding polypyrene-labeled derivatives, and the derivatives exhibited intramolecular excimer fluorescence (440-520 nm). In this study, dimercaprol and dithiothreitol were used as model polythiols. This polythiol analysis method is simple; it is also highly selective and sensitive and yields good calibration curves. PMID:19531896

  14. Simple and sensitive bacterial quantification by a flow-based kinetic exclusion fluorescence immunoassay.

    PubMed

    Su, Feng-yi; Endo, Yumie; Saiki, Hiroshi; Xing, Xin-Hui; Ohmura, Naoya

    2007-05-15

    A flow-based immunoassay system utilizing secondary-antibody coated microbeads and Cy5-secondary antibody for signal production was successfully developed to quantitate target bacteria with a kinetic exclusion assay (KinExA 3000 Instrument). It directly measured the concentration of unliganded antibody separated from the equilibrated mixture of antibody and bacteria through a 0.2 microm polyethersulfone membrane, enabling it to quantify the concentration of bacteria. The novel method demonstrated the qualities of rapidness, sensitivity, high accuracy and reproducibility, and ease to perform. Detection of Pseudomonas aeruginosa and Staphylococcus aureus was accomplished with low detection limits of 4.10 x 10(6) and 5.20 x l0(4)cells/mL, respectively, with an assay time of less than 15 min. The working ranges for quantification were 4.10 x l0(6) to 1.64 x l0(10)cells/mL for P. aeruginosa, and 5.20 x l0(4) to 1.04 x l0(9)cells/mL for S. aureus. It yielded an assay with at least 10-fold greater sensitivity than ELISA and could correctly assess the concentration of predominant bacterium spiked in the mixture of P. aeruginosa and S. aureus. With this reliable platform, the average amount of antibody bound by one cell in the maximum capability could be further provided: (1.6-2.5) x l0(5) antibodies for one P. aeruginosa cell and (2.2-2.7) x l0(8) antibodies for one S. aureus cell. The KinExA system is flexible to determine different kinds of bacteria conveniently by using anti-mouse IgG as the same immobilizing agent. However, a higher specificity of the antibodies to the target bacteria will be required for the use of this system with higher detection sensitivity. PMID:17097871

  15. A novel and simple fluorescent and colorimetric primary chemosensor based on Congo-Red for sulfite and resultant complex as secondary fluorescent chemosensor towards carbonate ions: Fluorescent probe mimicking INHIBIT logic gate.

    PubMed

    Tavallali, Hossein; Deilamy-Rad, Gohar; Parhami, Abolfath; Lohrasbi, Sajedeh

    2016-03-01

    A simple receptor based on Congo-Red (CR) was prepared by complexation of CR into two equivalents of Cu (II) ([CR-(Cu)2]) and it has been designed for detection of sulfite and carbonate ions. This chemosensor exhibits high sensitivity for sulfite over other anions in aqueous buffer solution. It exhibits colorimetric 'naked eye' and fluorometric responses to SO3(2-) which results from the addition of SO3(2)(-) to CR diazo moiety. Hereupon, CO3(2-) greatly limits the fluorescence of the resultant sulfite-receptor complex via a hydrogen bonding interaction ([CR-(Cu)2]-SO3). This system can be applied for selective detection of CO3(2-) in the presence of other anions. The detection limits of SO3(2-), calculated by the colorimetric and fluorometric methods, were found to be 0.07 and 0.09µmolL(-)(1), respectively. The sulfite-receptor complex also displayed the ability to detect up to 0.06µmolL(-)(1) CO3(2-). The fluorescence output mimicked 'INHIBIT' logic gate function. The output was exhibited by the intramolecular charge transfer of the [CR-(Cu)2] probe, and was provided by chemical inputs (SO3(2-) and CO3(2-)). PMID:26717828

  16. A simple Schiff base fluorescence probe for highly sensitive and selective detection of Hg(2+)and Cu(2.).

    PubMed

    Zhang, Caihong; Gao, Baozhen; Zhang, Qingyan; Zhang, Guomei; Shuang, Shaomin; Dong, Chuan

    2016-07-01

    A new Schiff base fluorescent probe, 2-(4-(diphenylamine)benzylidene) thiosemicarbazide (DPBT), was synthesized and its sensing behavior to metal ions were studied by UV-vis and fluorescence spectra. The results show that DPBT can detect Hg(2+)sensitively and selectively in weakly acidic and neutral conditions, they form a complex with 2:1. The linear range was 0.095-1.14µM and the detection limit was 0.15nM. In weakly alkaline conditions, DPBT can interaction with Hg(2+)and Cu(2+)at the same time. We use "masking" reagent, NaBH4, to reduce Hg(2+)to Hg°, the detection of Cu(2+)were achieved. They formed 1:1 complex with the binding constant of 4×10(4)M(-1), a good linear relationship in 0.45-3.6µM and the detection limit of 0.17µM. The proposed method was used to determine Hg(2+)and Cu(2+)in tap water and waste water samples. PMID:27154675

  17. Simple and Sensitive Molecularly Imprinted Polymer - Mn-Doped ZnS Quantum Dots Based Fluorescence Probe for Cocaine and Metabolites Determination in Urine.

    PubMed

    Chantada-Vázquez, María Pilar; Sánchez-González, Juan; Peña-Vázquez, Elena; Tabernero, María Jesús; Bermejo, Ana María; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

    2016-03-01

    A new molecularly imprinted polymer (MIP)-based fluorescent artificial receptor has been prepared by anchoring a selective MIP for cocaine (COC) on the surface of polyethylene glycol (PEG) modified Mn-doped ZnS quantum dots (QDs). The prepared material combines the high selectivity attributed to MIPs and the sensitive fluorescent property of the Mn-doped ZnS QDs. Simple and low cost methods have therefore been optimized for assessing cocaine abuse in urine by monitoring the fluorescence quenching when the template (COC) and also metabolites from COC [benzoylecgonine (BZE) and ecgonine methyl ester (EME)] are present. Fluorescence quenching was not observed when performing experiments with other drugs of abuse (and their metabolites) or when using nonimprinted polymer (NIP)-coated QDs. Under optimized operating conditions (1.5 mL of 200 mg L(-1) MIP-coated QDs solution, pH 5.5, and 15 min before fluorescence scanning) two analytical methods were developed/validated. One of the procedures (direct method) consisted of urine sample 1:20 dilution before fluorescence measurements. The method has been found to be fast, precise, and accurate, but the standard addition technique for performing the analysis was required because of the existence of matrix effect. The second procedure performed a solid phase extraction (SPE) first, avoiding matrix effect and allowing external calibration. The limits of detection of the methods were 0.076 mg L(-1) (direct method) and 0.0042 mg L(-1) (SPE based method), which are lower than the cutoff values for confirmative conclusions regarding cocaine abuse. PMID:26857857

  18. A simple naphthalene-based fluorescent probe for high selective detection of formaldehyde in toffees and HeLa cells via aza-Cope reaction.

    PubMed

    Xu, Junchao; Zhang, Yue; Zeng, Lintao; Liu, Jinbiao; Kinsella, Joseph M; Sheng, Ruilong

    2016-11-01

    A simple naphthalene-based fluorescent probe (AENO) for formaldehyde (FA) was successfully synthesized, which exhibited a significant fluorescence turn-on response towards FA in aqueous solution. The probe could quantitatively determine the concentration of FA (0-1.0mM) with excellent selectivity, high sensitivity and low limit of detection (0.57µM). The sensing mechanism was proposed as 2-aza-Cope rearrangement for AENO after reaction with FA, which was confirmed by (1)H NMR, HR-MS, FT-IR, UV-vis and fluorescence spectra. The probe has been employed to determine the FA contents in several commercially available toffee samples with satisfactory performance. Thus, AENO might be used as a promising tool for quantitative detection of FA in food. Furthermore, fluorescence imaging of HeLa cells indicated that the probe was cell membrane permeable and could be used for visualizing/imaging the FA trace/transportation in cancer cells. PMID:27591661

  19. A highly selective colorimetric and fluorescent chemosensor for Al(III) based-on simple naphthol in aqueous solution

    NASA Astrophysics Data System (ADS)

    Liu, Zhaodi; Xu, Huajie; Sheng, Liangquan; Chen, Shuisheng; Huang, Deqian; Liu, Jie

    2016-03-01

    A colorimetric and fluorescent chemosensor (L) for Al(III) was synthesized and fully characterized. L could be both used as a colorimetric and fluorescent chemosensor for the detection of Al3 + ions with low detection limit (8.87 × 10- 7 M) in CH3CN-H2O (1:1, v/v) solution. The binding ratio of L-Al3 + was determined from the Job plot (absorption and fluorescence spectra) and MALDI-TOF MS data to be 1:1. The binding constant (Ka) of Al3 + binding to L was calculated to be 4.8 × 105 M- 1 from a Benesi-Hildebrand plot. Moreover, the binding site of L with Al3 + was determined by 1H NMR titration experiment.

  20. A highly selective colorimetric and fluorescent chemosensor for Al(III) based-on simple naphthol in aqueous solution.

    PubMed

    Liu, Zhaodi; Xu, Huajie; Sheng, Liangquan; Chen, Shuisheng; Huang, Deqian; Liu, Jie

    2016-03-15

    A colorimetric and fluorescent chemosensor (L) for Al(III) was synthesized and fully characterized. L could be both used as a colorimetric and fluorescent chemosensor for the detection of Al(3+) ions with low detection limit (8.87×10(-7) M) in CH3CN-H2O (1:1, v/v) solution. The binding ratio of L-Al(3+) was determined from the Job plot (absorption and fluorescence spectra) and MALDI-TOF MS data to be 1:1. The binding constant (Ka) of Al(3+) binding to L was calculated to be 4.8×10(5) M(-1) from a Benesi-Hildebrand plot. Moreover, the binding site of L with Al(3+) was determined by (1)H NMR titration experiment. PMID:26690670

  1. A simple aptamer-based fluorescent assay for the detection of Aflatoxin B1 in infant rice cereal.

    PubMed

    Chen, Lu; Wen, Fang; Li, Ming; Guo, Xiaodong; Li, Songli; Zheng, Nan; Wang, Jiaqi

    2017-01-15

    A fluorescent assay for the rapid, sensitive and specific detection of Aflatoxin B1 (AFB1) was developed in this study. Initially, a DNA/DNA duplex was formed between a fluorescein-labeled AFB1 aptamer and its partially complementary DNA strand containing a quencher moiety, resulting in fluorescence quenching due to the close proximity of fluorophore and quencher. Upon the addition of AFB1, an aptamer/AFB1 complex was generated to release the quencher-modified DNA strand, thus recovered the fluorescence of fluorescein and enabled quantitative detection for AFB1 by monitoring fluorescence enhancement. Under optimized conditions, this assay exhibited a linear response to AFB1 in the range of 5-100ng/mL with a detection limit down to 1.6ng/mL. Trials of this assay in infant rice cereal with satisfactory recovery in the range of 93.0%-106.8%, demonstrate that the new assay could be a potential sensing platform for AFB1 determination in food. PMID:27542489

  2. A novel recombinant cell fluorescence biosensor based on toxicity of pathway for rapid and simple evaluation of DON and ZEN

    PubMed Central

    Ji, Jian; Gu, Wenshu; Sun, Chao; Sun, Jiadi; Jiang, Hui; Zhang, Yinzhi; Sun, Xiulan

    2016-01-01

    During an exposure, humans and animals are most often exposed to a mixture rather than individual mycotoxins. In this study, a Human Embryonic Kidney 293 cell (HEK-293) fluorescence sensor was developed to detect and evaluate mycotoxins, deoxynivalenol (DON) and zearalenone (ZEN) compounds, produced by Fusarium culmorum that are common food contaminants. TRE-copGFP (green fluorescent protein) and ERE-TagRFP (red fluorescent protein) plasmids were constructed and cotransfected into HEK-293 cells through a highly efficient, lipid-mediated, DNA-transfection procedure. Results show that fluorescence intensity was proportional to DON and ZEN concentrations, ranging from 2 to 40 ng/mL and 10 to 100 ng/mL respectively, with a detection limit of 0.75 ng/mL and 3.2 ng/mL respectively. The EC50 of DON and ZEN are 30.13 ng/mL and 76.63 ng/mL respectively. Additionally, ZEN may have a synergistic effect on enhancing AP-1 activity of the toxicity pathway of DON. These data indicate the high sensitivity and effectiveness of our biosensor system in the evaluation of the combined toxicity of ZEN, DON and their derivatives. In addition, this approach is suitable for an early warning method for the detection of ZEN and DON family mycotoxins contamination without higher-priced, conventional analytical chemistry methods. PMID:27498557

  3. A novel recombinant cell fluorescence biosensor based on toxicity of pathway for rapid and simple evaluation of DON and ZEN.

    PubMed

    Ji, Jian; Gu, Wenshu; Sun, Chao; Sun, Jiadi; Jiang, Hui; Zhang, Yinzhi; Sun, Xiulan

    2016-01-01

    During an exposure, humans and animals are most often exposed to a mixture rather than individual mycotoxins. In this study, a Human Embryonic Kidney 293 cell (HEK-293) fluorescence sensor was developed to detect and evaluate mycotoxins, deoxynivalenol (DON) and zearalenone (ZEN) compounds, produced by Fusarium culmorum that are common food contaminants. TRE-copGFP (green fluorescent protein) and ERE-TagRFP (red fluorescent protein) plasmids were constructed and cotransfected into HEK-293 cells through a highly efficient, lipid-mediated, DNA-transfection procedure. Results show that fluorescence intensity was proportional to DON and ZEN concentrations, ranging from 2 to 40 ng/mL and 10 to 100 ng/mL respectively, with a detection limit of 0.75 ng/mL and 3.2 ng/mL respectively. The EC50 of DON and ZEN are 30.13 ng/mL and 76.63 ng/mL respectively. Additionally, ZEN may have a synergistic effect on enhancing AP-1 activity of the toxicity pathway of DON. These data indicate the high sensitivity and effectiveness of our biosensor system in the evaluation of the combined toxicity of ZEN, DON and their derivatives. In addition, this approach is suitable for an early warning method for the detection of ZEN and DON family mycotoxins contamination without higher-priced, conventional analytical chemistry methods. PMID:27498557

  4. A rapid and simple 8-quinolinol-based fluorescent stain of phosphoproteins in polyacrylamide gel after electrophoresis.

    PubMed

    Wang, Xu; Hwang, Sun-Young; Cong, Wei-Tao; Jin, Li-Tai; Choi, Jung-Kap

    2015-10-01

    In order to obtain an easy and rapid protocol to visualize phosphoproteins in SDS-PAGE, a fluorescent detection method named 8-Quinolinol (8-Q) stain is described. 8-Q can form ternary complexes in the gel matrix contributed by the affinity of aluminum ion (Al(3+) ) to the phosphate groups on the proteins and the metal chelating property of 8-Quinolinol, exhibiting strong fluorescence in ultraviolet light. It can visualize as little as 4∼8 ng of α-casein and β-casein, 16∼32 ng of ovalbumin and κ-casein which is more sensitive than Stains-All but less sensitive than Pro-Q Diamond. The protocol of 8-Q requires only 70 min in 0.75 mm mini-size or 1.0 mm large-size gels with five changes of solutions without destaining step; Pro-Q takes at least 250 min with 11 changes of solutions. In addition, the new method was confirmed by the study of dephosphorylation and LC-MS/MS, respectively. The approach to visualize phosphoprotein utilizing 8-Q could be an alternative to simplify the analytical operations for phosphoproteomics research. PMID:26177935

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

    PubMed

    Başoğlu, Aysel; Tosun, Gonca; Ocak, Miraç; Alp, Hakan; Yaylı, 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

  6. Genetic diversity analysis of sugarcane germplasm based on fluorescence-labeled simple sequence repeat markers and a capillary electrophoresis-based genotyping platform

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic diversity analysis, which refers to the elaboration of total extent of genetic characteristics in the genetic makeup of a certain species, constitutes a classical strategy for the study of diversity, population genetic structure, and breeding practices. In this study, fluorescence-labeled se...

  7. A highly selective and simple fluorescent sensor for mercury (II) ion detection based on cysteamine-capped CdTe quantum dots synthesized by the reflux method.

    PubMed

    Ding, Xiaojie; Qu, Lingbo; Yang, Ran; Zhou, Yuchen; Li, Jianjun

    2015-06-01

    Cysteamine (CA)-capped CdTe quantum dots (QDs) (CA-CdTe QDs) were prepared by the reflux method and utilized as an efficient nano-sized fluorescent sensor to detect mercury (II) ions (Hg(2+) ). Under optimum conditions, the fluorescence quenching effect of CA-CdTe QDs was linear at Hg(2+) concentrations in the range of 6.0-450 nmol/L. The detection limit was calculated to be 4.0 nmol/L according to the 3σ IUPAC criteria. The influence of 10-fold Pb(2+) , Cu(2+) and Ag(+) on the determination of Hg(2+) was < 7% (superior to other reports based on crude QDs). Furthermore, the detection sensitivity and selectivity were much improved relative to a sensor based on the CA-CdTe QDs probe, which was prepared using a one-pot synthetic method. This CA-CdTe QDs sensor system represents a new feasibility to improve the detection performance of a QDs sensor by changing the synthesis method. PMID:25263990

  8. A simple but efficient strategy to enhance hydrostability of intensely fluorescent Mg-based coordination polymer (CP) via forming a composite of CP with hydrophobic PVDF.

    PubMed

    Zhai, Lu; Zhang, Wen-Wei; Zuo, Jing-Lin; Ren, Xiao-Ming

    2016-02-28

    A coordination polymer (CP) of Mg(2+) with 1,3,5-benzenetricarboxylate (BTC(3-)) was synthesized using a solvothermal method. The Mg-CP, with a formula of Mg3(BTC)(HCOO)3(DMF)3, crystallizes in the trigonal space group P3[combining macron], with cell parameters of a = b = 13.972(5) Å, c = 8.090(5) Å and V = 1367.6(11) Å(3), and shows a lamella structure built from planar rosette-type hexanuclear architectures. The Mg-CP emits intense blue fluorescence arising from π* → π transition of intra-ligand of BTC(3-) with 21.69% quantum yield, yet it exhibits poor stability to water. The composites of Mg-CP with hydrophobic polyvinylidene fluoride (PVDF) were sequentially prepared by mechanically mixed, tableted and annealed processes, which showed good compatibility between Mg-CP and PVDF, high hydrostability, and intense blue emission. This study suggests a simple but efficient method to solve the drawbacks of some functional CPs unstable to water and to promote them as practical applications in the field of functional materials. PMID:26790523

  9. A simple and sensitive fluorescence based biosensor for the determination of uric acid using H2O2-sensitive quantum dots/dual enzymes.

    PubMed

    Azmi, Nur Ellina; Ramli, Noor Izaanin; Abdullah, Jaafar; Abdul Hamid, Mohammad Azmi; Sidek, Hamidah; Abd Rahman, Samsulida; Ariffin, Nurhayati; Yusof, Nor Azah

    2015-05-15

    A novel optical detection system consisting of combination of uricase/HRP-CdS quantum dots (QDs) for the determination of uric acid in urine sample is described. The QDs was used as an indicator to reveal fluorescence property of the system resulting from enzymatic reaction of uricase and HRP (horseradish peroxidase), which is involved in oxidizing uric acid to allaintoin and hydrogen peroxide. The hydrogen peroxide produced was able to quench the QDs fluorescence, which was proportional to uric acid concentration. The system demonstrated sufficient activity of uricase and HRP at a ratio of 5U:5U and pH 7.0. The linearity of the system toward uric acid was in the concentration range of 125-1000 µM with detection limit of 125 µM. PMID:25113659

  10. Evaluating Sense Codon Reassignment with a Simple Fluorescence Screen.

    PubMed

    Biddle, Wil; Schmitt, Margaret A; Fisk, John D

    2015-12-22

    Understanding the interactions that drive the fidelity of the genetic code and the limits to which modifications can be made without breaking the translational system has practical implications for understanding the molecular mechanisms of evolution as well as expanding the set of encodable amino acids, particularly those with chemistries not provided by Nature. Because 61 sense codons encode 20 amino acids, reassigning the meaning of sense codons provides an avenue for biosynthetic modification of proteins, furthering both fundamental and applied biochemical research. We developed a simple screen that exploits the absolute requirement for fluorescence of an active site tyrosine in green fluorescent protein (GFP) to probe the pliability of the degeneracy of the genetic code. Our screen monitors the restoration of the fluorophore of GFP by incorporation of a tyrosine in response to a sense codon typically assigned another meaning in the genetic code. We evaluated sense codon reassignment at four of the 21 sense codons read through wobble interactions in Escherichia coli using the Methanocaldococcus jannaschii orthogonal tRNA/aminoacyl tRNA synthetase pair originally developed and commonly used for amber stop codon suppression. By changing only the anticodon of the orthogonal tRNA, we achieved sense codon reassignment efficiencies between 1% (Phe UUU) and 6% (Lys AAG). Each of the orthogonal tRNAs preferentially decoded the codon traditionally read via a wobble interaction in E. coli with the exception of the orthogonal tRNA with an AUG anticodon, which incorporated tyrosine in response to both the His CAU and His CAC codons with approximately equal frequencies. We applied our screen in a high-throughput manner to evaluate a 10(9)-member combined tRNA/aminoacyl tRNA synthetase library to identify improved sense codon reassigning variants for the Lys AAG codon. A single rapid screen with the ability to broadly evaluate reassignable codons will facilitate

  11. Highly sensitive and simple fluorescence staining of proteins in sodium dodecyl sulfate-polyacrylamide-based gels by using hydrophobic tail-mediated enhancement of fluorescein luminescence.

    PubMed

    Kang, Chulhun; Kim, Hyun Jung; Kang, Donghoon; Jung, Duk Young; Suh, Myungkoo

    2003-10-01

    Fluorescein has an extremely low luminescence intensity in acidic aqueous media. However, when it was bound to proteins, subsequent increase of luminescence intensity took place. Furthermore, when a hydrophobic tail, such as aliphatic hydrocarbons, was introduced to fluorescein, more dramatic increase of luminescence intensity was observed upon binding to proteins. In the present study, by utilizing this luminescence enhancement, three hydrophobic fluorescein dyes (5-dodecanoyl amino fluorescein, 5-hexadecanoyl amino fluorescein, and 5-octadecanoyl amino fluorescein) were examined as noncovalent fluorescent stains of protein bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Effective incorporation of the dyes to proteins in gels was accomplished either simply by adding dyes at the protein fixation step, or by treating gels with a staining solution after the fixation. The sensitivity of this staining method using the fluorescein derivatives was approximately 1 ng/band for most proteins. For some cases, protein bands containing as low as 0.1 ng were successfully visualized. In addition, the detection sensitivity showed much less protein-to-protein variation than silver staining. This new staining method was also successfully applied to two-dimensional electrophoresis of rat brain proteins. Its overall sensitivity was comparable to that of silver staining. PMID:14595675

  12. 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-μs-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).

  13. 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.

  14. 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.

  15. Selection of fluorescent DNA dyes for real-time LAMP with portable and simple optics.

    PubMed

    Seyrig, Gregoire; Stedtfeld, Robert D; Tourlousse, Dieter M; Ahmad, Farhan; Towery, Keara; Cupples, Alison M; Tiedje, James M; Hashsham, Syed A

    2015-12-01

    Loop-mediated isothermal amplification (LAMP) is increasingly used for point-of-care nucleic acid based diagnostics. LAMP can be monitored in real-time by measuring the increase in fluorescence of DNA binding dyes. However, there is little information comparing the effect of various fluorescent dyes on signal to noise ratio (SNR) or threshold time (Tt). This information is critical for implementation with field deployable diagnostic tools that require small, low power consumption, robust, and inexpensive optical components with reagent saving low volume reactions. In this study, SNR and Tt during real-time LAMP was evaluated with eleven fluorescent dyes. Of all dyes tested, SYTO-82, SYTO-84, and SYTOX Orange resulted in the shortest Tt, and SYTO-81 had the widest range of working concentrations. The optimized protocol detected 10 genome copies of Mycobacterium tuberculosis in less than 10 min, 10 copies of Giardia intestinalis in ~20 min, and 10 copies of Staphylococcus aureus or Salmonella enterica in less than 15 min. Results demonstrate that reaction efficiency depends on both dye type and concentration and the selected polymerase. The optimized protocol was evaluated in the Gene-Z™ device, a hand-held battery operated platform characterized via simple and low cost optics, and a multiple assay microfluidic chip with micron volume reaction wells. Compared to the more conventional intercalating dye (SYBR Green), reliable amplification was only observed in the Gene-Z™ when using higher concentrations of SYTO-81. PMID:26554941

  16. Multiphoton excitation fluorescence correlation spectroscopy of fluorescent DNA base analogs

    NASA Astrophysics Data System (ADS)

    Katilius, Evaldas; Woodbury, Neal W.

    2004-06-01

    Two- and three-photon excitation was used to investigate the properties of two fluorescent DNA base analogs: 2-aminopurine and 6-methylisoxanthopterin. 2-aminopurine is a widely used fluorescent analog of the DNA base adenine. Three-photon excitation of 2-aminopurine is achievable by using intense femtosecond laser pulses in 850-950 nm spectral region. Interestingly, the three-photon excitation spectrum is blue-shifted relative to the three-times-wavelength single-photon excitation spectrum. The maximum of the absorbance band in the UV is at 305 nm, while the three-photon excitation spectrum has a maximum at around 880 nm. Fluorescence correlation measurements were attempted to evaluate the feasibility of using three-photon excitation of 2-aminopurine for DNA-protein interaction studies. However, due to relatively small three-photon absorption cross-section, a good signal-to-noise fluorescence correlation curves take very long time to obtain. Fluorescence properties of 6-methylisoxanthopterin, the fluorescent analog of guanine, were investigated using two-photon excitation. This molecule has the lowest energy absorption band centered around 350 nm, thus, two-photon excitation is attainable using 700 to 760 nm output of Ti-sapphire laser. The excitation spectrum of this molecule in the infrared well matches the doubled-wavelength single-photon excitation spectrum in the UV. The high fluorescence quantum yield of 6-methylisoxanthopterin allows efficient fluorescence correlation measurements and makes this molecule a very good candidate for using in in vitro DNA-protein interaction studies.

  17. Fluorescent sensors based on bacterial fusion proteins

    NASA Astrophysics Data System (ADS)

    Prats Mateu, Batirtze; Kainz, Birgit; Pum, Dietmar; Sleytr, Uwe B.; Toca-Herrera, José L.

    2014-06-01

    Fluorescence proteins are widely used as markers for biomedical and technological purposes. Therefore, the aim of this project was to create a fluorescent sensor, based in the green and cyan fluorescent protein, using bacterial S-layers proteins as scaffold for the fluorescent tag. We report the cloning, expression and purification of three S-layer fluorescent proteins: SgsE-EGFP, SgsE-ECFP and SgsE-13aa-ECFP, this last containing a 13-amino acid rigid linker. The pH dependence of the fluorescence intensity of the S-layer fusion proteins, monitored by fluorescence spectroscopy, showed that the ECFP tag was more stable than EGFP. Furthermore, the fluorescent fusion proteins were reassembled on silica particles modified with cationic and anionic polyelectrolytes. Zeta potential measurements confirmed the particle coatings and indicated their colloidal stability. Flow cytometry and fluorescence microscopy showed that the fluorescence of the fusion proteins was pH dependent and sensitive to the underlying polyelectrolyte coating. This might suggest that the fluorescent tag is not completely exposed to the bulk media as an independent moiety. Finally, it was found out that viscosity enhanced the fluorescence intensity of the three fluorescent S-layer proteins.

  18. A simple dental caries detection system using full spectrum of laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Rocha-Cabral, Renata Maciel; Mendes, Fausto Medeiros; Maldonado, Edison Puig; Zezell, Denise Maria

    2015-06-01

    Objectives: to develop an apparatus for the detection of early caries lesions in enamel using the full extent of the tooth fluorescence spectrum, through the integration of a laser diode, fiber optics, filters and one portable spectrometer connected to a computer, all commercially available; to evaluate the developed device in clinical and laboratory tests, and compare its performance with commercial equipment. Methods: clinical examinations were performed in patients with indication for exodontics of premolars. After examinations, the patients underwent surgery and the teeth were stored individually. The optical measurements were repeated approximately two months after extraction, on the same sites previously examined, then histological analysis was carried out. Results: the spectral detector has presented high specificity and moderate sensitivity when applied to differentiate between healthy and damaged tissues, with no significant differences from the performance of the commercial equipment. The developed device is able to detect initial damages in enamel, with depth of approximately 300 μm. Conclusions: we successfully demonstrated the development of a simple and portable system based in laser-induced fluorescence for caries detection, assembled from common commercial parts. As the spectral detector acquires a complete recording of the spectrum from each tissue, it is possible to use it for monitoring developments of caries lesions.

  19. 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

  20. A simple method for fabrication of enhanced fluorescence substrate on TEM copper grid

    NASA Astrophysics Data System (ADS)

    Dong, Jun; Du, Yabing; Qi, Jianxia; Zhang, Wenwen; Li, Wenyang

    2013-09-01

    A simple method to fabricate enhanced fluorescence substrates was experimentally demonstrated. The fabricated substrate, consisting of silver dendrites, was manufactured by a modified galvanic displacement process between Ag ions and TEM grid at room temperature. Substrate enhancement efficiency, which was evaluated from fluorescence spectrum intensities of the adsorbed Rhodamine 6G (Rh6G) molecules, was found to increase rapidly with reaction time. The observation highlights the importance of strong coupling effects between silver nanobranches and the variation of SEF efficiency can be qualitatively explained with the local surface plasmon resonance model of coupled silver nanostructures. As a result, with a laser, a spectrometer, some second-hand TEM grids, and simple chemical agents, we can easily fabricate the enhanced substrate, which can be applied to study surface enhanced fluorescence, one of the research focuses currently.

  1. A simple and compact fluorescence detection system for capillary electrophoresis and its application to food analysis.

    PubMed

    Zhai, Haiyun; Yuan, Kaisong; Yu, Xiao; Chen, Zuanguang; Liu, Zhenping; Su, Zihao

    2015-10-01

    A novel fluorescence detection system for CE was described and evaluated. Two miniature laser pointers were used as the excitation source. A Y-style optical fiber was used to transmit the excitation light and a four-branch optical fiber was used to collect the fluorescence. The optical fiber and optical filter were imported into a photomultiplier tube without any extra fixing device. A simplified PDMS detection cell was designed with guide channels through which the optical fibers were easily aligned to the detection window of separation capillary. According to different requirements, laser pointers and different filters were selected by simple switching and replacement. The fluorescence from four different directions was collected at the same detecting point. Thus, the sensitivity was enhanced without peak broadening. The fluorescence detection system was simple, compact, low-cost, and highly sensitive, with its functionality demonstrated by the separation and determination of red dyes and fluorescent whitening agents. The detection limit of rhodamine 6G was 7.7 nM (S/N = 3). The system was further applied to determine illegal food dyes. The CE system is potentially eligible for food safety analysis. PMID:26109527

  2. Radiative Transport Based Frequency Domain Fluorescence Tomography

    PubMed Central

    Joshi, Amit; Rasmussen, John C.; Sevick-Muraca, Eva M.; Wareing, Todd A.; McGhee, John

    2011-01-01

    We report the development of radiative transport model based fluorescence optical tomography from frequency domain boundary measurements. The coupled radiative transport model for describing NIR fluorescence propagation in tissue is solved by a novel software based on the established Attila™ particle transport simulation platform. The proposed scheme enables the prediction of fluorescence measurements with non-contact sources and detectors at minimal computational cost. An adjoint transport solution based fluorescence tomography algorithm is implemented on dual grids to efficiently assemble the measurement sensitivity Jacobian matrix. Finally, we demonstrate fluorescence tomography on a realistic computational mouse model to locate nM to μM fluorophore concentration distributions in simulated mouse organs. PMID:18364555

  3. A fluorescence high-temperature sensor based on fluorescence lifetime

    NASA Astrophysics Data System (ADS)

    Wu, Jinling; Wang, Yutian; Wang, Xinian

    2006-11-01

    A kind of fluorescence optic-fiber temperature sensor is devised based on the alexandrite crystal. In this system, a new optic- fiber probe fabrication techniques is proposed. This system is particularly adapted to the temperature measurement in the range of room temperature to 650°C. During the cause of experimentation, using the PLD-PMTR (termed the Pulse Modulated Phase-locked detection with Two References) signal processing scheme. This temperature measurement method is proved to be effective and useful for its highly resolution and precision. It ensured the detected fluorescence signal to noise ratio was high enough to be measurable when the temperature is raised to 650°C.

  4. Fluorescence spectra shape based dynamic thermometry

    NASA Astrophysics Data System (ADS)

    Liu, Liwang; Creten, Sebastiaan; Firdaus, Yuliar; Agustin Flores Cuautle, Jose Jesus; Kouyaté, Mansour; Van der Auweraer, Mark; Glorieux, Christ

    2014-01-01

    An entirely optical, dynamic thermometry technique based on the temperature dependence of a fluorescence spectrum is presented. Different from conventional intensity-based fluorescence thermometry, in this work, neural network recognition is employed to extract the sample temperature from the magnitude and shape of recorded fluorescence spectra. As a demonstration to determine the depth profile of dynamical temperature variations and of the thermal and optical properties of semitransparent samples, in-depth photothermally induced periodical temperature oscillations of a rhodamine B and copper chloride dyed glycerol sample were measured with an accuracy of 4.2 mK.Hz-1/2 and fitted well by a 1D thermal diffusion model.

  5. Carbon Nanoparticle-based Fluorescent Bioimaging Probes

    PubMed Central

    Bhunia, Susanta Kumar; Saha, Arindam; Maity, Amit Ranjan; Ray, Sekhar C.; Jana, Nikhil R.

    2013-01-01

    Fluorescent nanoparticle-based imaging probes have advanced current labelling technology and are expected to generate new medical diagnostic tools based on their superior brightness and photostability compared with conventional molecular probes. Although significant progress has been made in fluorescent semiconductor nanocrystal-based biological labelling and imaging, the presence of heavy metals and the toxicity issues associated with heavy metals have severely limited the application potential of these nanocrystals. Here, we report a fluorescent carbon nanoparticle-based, alternative, nontoxic imaging probe that is suitable for biological staining and diagnostics. We have developed a chemical method to synthesise highly fluorescent carbon nanoparticles 1–10 nm in size; these particles exhibit size-dependent, tunable visible emission. These carbon nanoparticles have been transformed into various functionalised nanoprobes with hydrodynamic diameters of 5–15 nm and have been used as cell imaging probes. PMID:23502324

  6. A simple and general route for monofunctionalization of fluorescent and magnetic nanoparticles using peptides

    NASA Astrophysics Data System (ADS)

    Clarke, Samuel; Tamang, Sudarsan; Reiss, Peter; Dahan, Maxime

    2011-04-01

    Nanoparticles are now utilized in many diverse biological and medical applications. Despite this, it remains challenging to tailor their surface for specific molecular targeting while maintaining high biocompatibility. To address this problem, we evaluate a phytochelatin-related peptide surface coating to produce functional and biocompatible nanoparticles (NPs) based on fluorescent InP/ZnS and CdSe/ZnS or superparamagnetic FePt and Fe3O4. Using a combination of transmission electron microscopy, size-exclusion chromatography and gel electrophoresis (GE), we demonstrate the excellent colloidal properties of the peptide-coated NPs (pNPs) and the compact nature of the coating (~4 nm thickness). We develop a simple protocol for the monofunctionalization of the pNPs with targeting biomolecules, by combining covalent conjugation with GE purification. We then employ functionalized InP/ZnS pNPs in a live-cell, single-molecule imaging application to specifically target and detect individual proteins in the cell membrane. These findings showcase the versatility of the peptides for preparing compact NPs of various compositions and sizes, which are easily functionalized, and suitable for a broad range of biomedical applications.

  7. Multiphoton excitation of fluorescent DNA base analogs

    NASA Astrophysics Data System (ADS)

    Katilius, Evaldas; Woodbury, Neal W.

    2006-07-01

    Multiphoton excitation was used to investigate properties of the fluorescent DNA base analogs, 2-aminopurine (2AP) and 6-methylisoxanthopterin (6MI). 2-aminopurine, a fluorescent analog of adenine, was excited by three-photon absorption. Fluorescence correlation measurements were attempted to evaluate the feasibility of using three-photon excitation of 2AP for DNA-protein interaction studies. However, high excitation power and long integration times needed to acquire high signal-to-noise fluorescence correlation curves render three-photon excitation FCS of 2AP not very useful for studying DNA base dynamics. The fluorescence properties of 6-methylisoxanthopterin, a guanine analog, were investigated using two-photon excitation. The two-photon absorption cross-section of 6MI was estimated to be about 2.5×10-50 cm4s (2.5 GM units) at 700 nm. The two-photon excitation spectrum was measured in the spectral region from 700 to 780 nm; in this region the shape of the two-photon excitation spectrum is very similar to the shape of single-photon excitation spectrum in the near-UV spectral region. Two-photon excitation of 6MI is suitable for fluorescence correlation measurements. Such measurements can be used to study DNA base dynamics and DNA-protein interactions over a broad range of time scales.

  8. a Simple, Cost Effective Raman-Fluorescence Spectrometer for Use in Laboratory and Field Experiments

    NASA Astrophysics Data System (ADS)

    Marshall, Frank E.; Pride, Michael A.; Rojo, Michellle; Brinker, Katelyn R.; Walker, Zachary; Storrie-Lombardi, Michael; Mormile, Melanie R.; Grubbs, G. S., II

    2015-06-01

    Research, design, construction, and operation of a portable mixed Raman and Fluorescence type spectrometer implemented by the Missouri University of Science and Technology's Mars Rover Design Team will be presented. This spectrometer has been built for the team's annual competition. The spectrometer, completely built by undergraduates, is designed to use a 50 mW, 532 nm constant waveform laser to probe a sample of soil to find bacteria or bio-markers. However, initial tests of the spectrometer were carried out in a laboratory environment making the spectrometer also suitable for simple undergraduate physical chemistry or chemical physics laboratory experiments. The final cost of the device is roughly 2100, weighs 1.4 kg, and is 22.9 cm x 22.6 cm in size. Integrating the spectrometer with a computer database, results from the competition, complications of fitting mixed Raman-Fluorescence spectra, and future ideas/improvements will also be discussed.

  9. Paper-based microfluidic device with upconversion fluorescence assay.

    PubMed

    He, Mengyuan; Liu, Zhihong

    2013-12-17

    A paper-based microfluidic device with upconversion fluorescence assay (named as UC-μPAD) is proposed. The device is fabricated on a normal office printing sheet with a simple plotting method. Upconversion phosphors (UCPs) tagged with specific probes are spotted to the test zones on the μPAD, followed by the introduction of assay targets. Upconversion fluorescence measurements are directly conducted on the test zones after the completion of the probe-to-target reactions, without any post-treatments. The UC-μPAD features very easy fabrication and operation, simple and fast detection, low cost, and high sensitivity. UC-μPAD is a promising prospect for a clinical point-of-care test. PMID:24308347

  10. A simple preparation of Ag@graphene nanocomposites for surface-enhanced Raman spectroscopy of fluorescent anticancer drug

    NASA Astrophysics Data System (ADS)

    Meng, Ying; Yan, Xueying; Wang, Yi

    2016-05-01

    A simple method was developed to synthesize Ag@graphene nanocomposites with rough Ag nanoparticles (AgNPs) conjugated with graphene nanosheets, and the nanocomposites could be used as substrates for effective surface-enhanced Raman spectroscopy (SERS) of fluorescent anticancer drug (Dox) since they could not only enhance the Raman signals but also suppress the fluorescent signals.

  11. Simple road detection based on vanishing point

    NASA Astrophysics Data System (ADS)

    Ziyu, Chen; Zhen, He

    2014-05-01

    Vision-based road detection is one of the key techniques of autonomous driving, intelligent vehicles, and visual navigation. At present, methods based on vanishing point perform best with general roads. However, it is difficult for them to meet the needs of a real-time system due to high time consumption. This paper presents a fast detection method, namely simple road detection, which achieves high efficiency by employing sky segmentation and two new optimization schemes-sample convolution and fast voting. The optimizations are based on lookup tables, sample computing, and computing simplification. The interval sampling in sample convolution makes the proposed method flexible to meet various efficiency and accuracy demands by different sample-step values. Mean filter and vote orientation limitation are also proposed to help improve detection accuracy. Experiments have been conducted with a large number of road images under different environmental conditions, and the results demonstrate that our proposed method is efficient and effective in detecting both structured and unstructured roads.

  12. 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.

  13. 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

  14. Preparation of a novel fluorescent nanocomposite: CeO2 / ANS by a simple method

    NASA Astrophysics Data System (ADS)

    Liu, X.; Lian, X.; Li, Y.; Zhang, N.

    2012-03-01

    For the first time, a novel fluorescent material, composed of CeO2/ANS nanocomposites was successfully synthesized by a simple ultrasonic method, using CeO2 nanoparticles and 8-anilino-1-naphthalenesulfonic acid (ANS) as the raw materials. The samples were characterized by scanning electron microscope (SEM), photoluminescence spectroscopy and Fourier transformation infrared spectroscopy (FTIR). The results showed that the PL intensity of the CeO2/ANS nanocomposites was higher than that of both CeO2 nanoparticles and ANS powders, and the peak wavelength was also different from the peak wavelength typical of each of the used materials, which suggests that the chemical reaction occurs between CeO2 nanoparticles and ANS molecules. In addition, the effect of the ANS concentrations on the photoluminescence of the nanocomposites was also investigated.

  15. A Simple and Rapid Protocol for Measuring Neutral Lipids in Algal Cells Using Fluorescence

    PubMed Central

    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

  16. Economic and simple system to combine single-spot photolysis and whole-field fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Jaafari, Nadia; Henson, Mark; Graham, Jeremy; Canepari, Marco

    2013-06-01

    In recent years, the use of light emitting diodes (LEDs) has become commonplace in fluorescence microscopy. LEDs are economical and easy to couple to commercial microscopes, and they provide powerful and stable light that can be triggered by transistor-transistor logic pulses in the range of tens of microseconds or shorter. LEDs are usually installed on the epifluorescence port of the microscope to obtain whole-field illumination, which is ideal for fluorescence imaging. In contrast, photolysis or channelrhodopsin stimulation often requires localized illumination, typically achieved using lasers. Here we show that insertion of a long-pass (>411 nm) filter with an appropriately sized pinhole in the epifluorescence pathway, combined with dual UV/visible illumination, can produce efficient whole-field visible illumination and spot UV illumination of 15 to 20 μm. We tested our system by performing calcium imaging experiments combined with L-glutamate or N-methyl-D-aspartic acid (NMDA) photorelease in hippocampal neurons from brain slices or dissociated cultures, demonstrating the ability to obtain local activation of NMDA receptors exclusively in the illuminated spot. The very inexpensive and simple system that we report here will allow many laboratories with limited budgets to run similar experiments in a variety of physiological applications.

  17. Economic and simple system to combine single-spot photolysis and whole-field fluorescence imaging.

    PubMed

    Jaafari, Nadia; Henson, Mark; Graham, Jeremy; Canepari, Marco

    2013-06-01

    ABSTRACT. In recent years, the use of light emitting diodes (LEDs) has become commonplace in fluorescence microscopy. LEDs are economical and easy to couple to commercial microscopes, and they provide powerful and stable light that can be triggered by transistor-transistor logic pulses in the range of tens of microseconds or shorter. LEDs are usually installed on the epifluorescence port of the microscope to obtain whole-field illumination, which is ideal for fluorescence imaging. In contrast, photolysis or channelrhodopsin stimulation often requires localized illumination, typically achieved using lasers. Here we show that insertion of a long-pass (>411  nm) filter with an appropriately sized pinhole in the epifluorescence pathway, combined with dual UV/visible illumination, can produce efficient whole-field visible illumination and spot UV illumination of 15 to 20 μm. We tested our system by performing calcium imaging experiments combined with L-glutamate or N-methyl-D-aspartic acid (NMDA) photorelease in hippocampal neurons from brain slices or dissociated cultures, demonstrating the ability to obtain local activation of NMDA receptors exclusively in the illuminated spot. The very inexpensive and simple system that we report here will allow many laboratories with limited budgets to run similar experiments in a variety of physiological applications. PMID:23764747

  18. 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

  19. Teaching about photosynthesis with simple equipment: analysis of light-induced changes in fluorescence and reflectance of plant leaves.

    PubMed

    Björn, Lars Olof; Li, Shaoshan

    2013-10-01

    Solar energy absorbed by plants results in either reflection or absorption. The latter results in photosynthesis, fluorescence, or heat. Measurements of fluorescence changes have been used for monitoring processes associated with photosynthesis. A simple method to follow changes in leaf fluorescence and leaf reflectance associated with nonphotochemical quenching and light acclimation of leaves is described. The main equipment needed consists of a green-light emitting laser pointer, a digital camera, and a personal computer equipped with the camera acquisition software and the programs ImageJ and Excel. Otherwise, only commonly available cheap materials are required. PMID:23728512

  20. Fluorescence lifetime-based optical molecular imaging.

    PubMed

    Kumar, Anand T N

    2011-01-01

    Fluorescence lifetime is a powerful contrast mechanism for in vivo molecular imaging. In this chapter, we describe instrumentation and methods to optimally exploit lifetime contrast using a time domain fluorescence tomography system. The key features of the system are the use of point excitation in free-space using ultrashort laser pulses and non-contact detection using a gated, intensified CCD camera. The surface boundaries of the imaging volume are acquired using a photogrammetric camera integrated with the imaging system, and implemented in theoretical models of light propagation in biological tissue. The time domain data are optimally analyzed using a lifetime-based tomography approach, which is based on extracting a tomographic set of lifetimes and decay amplitudes from the long time decay portion of the time domain data. This approach improves the ability to locate in vivo targets with a resolution better than conventional optical methods. The application of time domain lifetime multiplexing and tomography are illustrated using phantoms and tumor bearing mouse model of breast adenocarcinoma. In the latter application, the time domain approach allows an improved detection of fluorescent protein signals from intact nude mice in the presence of background autofluorescence. This feature has potential applications for longitudinal pre-clinical evaluation of drug treatment response as well as to address fundamental questions related to tumor physiology and metastasis. PMID:21153381

  1. Optical fiber-based fluorescent viscosity sensor

    NASA Astrophysics Data System (ADS)

    Haidekker, Mark A.; Akers, Walter J.; Fischer, Derek; Theodorakis, Emmanuel A.

    2006-09-01

    Molecular rotors are a unique group of viscosity-sensitive fluorescent probes. Several recent studies have shown their applicability as nonmechanical fluid viscosity sensors, particularly in biofluids containing proteins. To date, molecular rotors have had to be dissolved in the fluid for the measurement to be taken. We now show that molecular rotors may be covalently bound to a fiber-optic tip without loss of viscosity sensitivity. The optical fiber itself may be used as a light guide for emission light (external illumination of the tip) as well as for both emission and excitation light. Covalently bound molecular rotors exhibit a viscosity-dependent intensity increase similar to molecular rotors in solution. An optical fiber-based fluorescent viscosity sensor may be used in real-time measurement applications ranging from biomedical applications to the food industry.

  2. Antibody-based fluorescent and fluorescent ratiometric indicators for detection of phosphotyrosine.

    PubMed

    Huynh Nhat, Kim Phuong; Watanabe, Takayoshi; Yoshikoshi, Kensuke; Hohsaka, Takahiro

    2016-08-01

    Fluorescent indicators for protein phosphorylation are very important in not only fundamental biology but also biomedical applications. In this study, we developed novel fluorescent and fluorescent ratiometric indicators for detection of phosphotyrosine (pTyr) derivatives. A single-chain antibody variable fragment (scFv) against phosphotyrosine was fluorescent-labeled by incorporation of tetramethylrhodamine (TAMRA)-linked nonnatural amino acid at the N- or C-terminus. The TAMRA-labeled scFv showed fluorescence enhancement upon addition of pTyr-containing peptides based on antigen-dependent fluorescence quenching effect on TAMRA. The TAMRA-labeled scFv was further fused with enhanced green fluorescent protein (EGFP) to generate a double-labeled scFv for pTyr. In the absence of antigen, fluorescence resonance energy transfer (FRET) occurred from EGFP to TAMRA but TAMRA was quenched. The antigen-binding removed the quenching of TAMRA while FRET occurred without altering its efficiency. As a result of the FRET and antigen-dependent fluorescence quenching effect, the double-labeled scFv exhibited fluorescence ratio enhancement upon the antigen-binding. The fluorescent and fluorescent ratiometric indicators obtained in this study will become a novel tool for analysis of protein phosphorylation. Moreover, this strategy utilizes antibody derivatives, and therefore, can be easily applied to other antigen-antibody pairs to generate fluorescent ratiometric indicators for various target molecules. PMID:26896314

  3. A Simple BODIPY-Based Viscosity Probe for Imaging of Cellular Viscosity in Live Cells.

    PubMed

    Su, Dongdong; Teoh, Chai Lean; Gao, Nengyue; Xu, Qing-Hua; Chang, Young-Tae

    2016-01-01

    Intracellular viscosity is a fundamental physical parameter that indicates the functioning of cells. In this work, we developed a simple boron-dipyrromethene (BODIPY)-based probe, BTV, for cellular mitochondria viscosity imaging by coupling a simple BODIPY rotor with a mitochondria-targeting unit. The BTV exhibited a significant fluorescence intensity enhancement of more than 100-fold as the solvent viscosity increased. Also, the probe showed a direct linear relationship between the fluorescence lifetime and the media viscosity, which makes it possible to trace the change of the medium viscosity. Furthermore, it was demonstrated that BTV could achieve practical applicability in the monitoring of mitochondrial viscosity changes in live cells through fluorescence lifetime imaging microscopy (FLIM). PMID:27589762

  4. Multispectral excitation based multiple fluorescent targets resolving in fluorescence molecular tomography

    NASA Astrophysics Data System (ADS)

    Zhou, Yuan; Guang, Huizhi; Pu, Huangsheng; Zhang, Jiulou; Bai, Jing; Luo, Jianwen

    2016-04-01

    Fluorescence molecular tomography (FMT) can visualize biological activities at cellular and molecular levels in vivo, and has been extensively used in drug delivery and tumor detection research of small animals. The ill-posedness of the FMT inverse problem makes it difficult to reconstruct and resolve multiple adjacent fluorescent targets that have different functional features but are labeled with the same fluorochrome. An algorithm based on independent component analysis (ICA) for multispectral excited FMT is proposed to resolve multiple fluorescent targets in this study. Fluorescent targets are excited by multispectral excitation, and the three-dimensional distribution of fluorescent yields under the excitation spectrum is reconstructed by an iterative Tikhonov regularization algorithm. Subsequently, multiple fluorescent targets are resolved from mixed fluorescence signals by employing ICA. Simulations were performed and the results demonstrate that multiple adjacent fluorescent targets can be resolved if the number of excitation wavelengths is not smaller than that of fluorescent targets with different concentrations. The algorithm obtains both independent components that provide spatial information of different fluorescent targets and spectral courses that reflect variation trends of fluorescent yields along with the excitation spectrum. By using this method, it is possible to visualize the metabolism status of drugs in different structure organs, and quantitatively depict the variation trends of fluorescent yields of each functional organ under the excitation spectrum. This method may provide a pattern for tumor detection, drug delivery and treatment monitoring in vivo.

  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. Site-specific analysis of protein hydration based on unnatural amino acid fluorescence.

    PubMed

    Amaro, Mariana; Brezovský, Jan; Kováčová, Silvia; Sýkora, Jan; Bednář, David; Němec, Václav; Lišková, Veronika; Kurumbang, Nagendra Prasad; Beerens, Koen; Chaloupková, Radka; Paruch, Kamil; Hof, Martin; Damborský, Jiří

    2015-04-22

    Hydration of proteins profoundly affects their functions. We describe a simple and general method for site-specific analysis of protein hydration based on the in vivo incorporation of fluorescent unnatural amino acids and their analysis by steady-state fluorescence spectroscopy. Using this method, we investigate the hydration of functionally important regions of dehalogenases. The experimental results are compared to findings from molecular dynamics simulations. PMID:25815779

  7. Fluorescent Protein Based FRET Pairs with Improved Dynamic Range for Fluorescence Lifetime Measurements.

    PubMed

    George Abraham, Bobin; Sarkisyan, Karen S; Mishin, Alexander S; Santala, Ville; Tkachenko, Nikolai V; Karp, Matti

    2015-01-01

    Fluorescence Resonance Energy Transfer (FRET) using fluorescent protein variants is widely used to study biochemical processes in living cells. FRET detection by fluorescence lifetime measurements is the most direct and robust method to measure FRET. The traditional cyan-yellow fluorescent protein based FRET pairs are getting replaced by green-red fluorescent protein variants. The green-red pair enables excitation at a longer wavelength which reduces cellular autofluorescence and phototoxicity while monitoring FRET. Despite the advances in FRET based sensors, the low FRET efficiency and dynamic range still complicates their use in cell biology and high throughput screening. In this paper, we utilized the higher lifetime of NowGFP and screened red fluorescent protein variants to develop FRET pairs with high dynamic range and FRET efficiency. The FRET variations were analyzed by proteolytic activity and detected by steady-state and time-resolved measurements. Based on the results, NowGFP-tdTomato and NowGFP-mRuby2 have shown high potentials as FRET pairs with large fluorescence lifetime dynamic range. The in vitro measurements revealed that the NowGFP-tdTomato has the highest Förster radius for any fluorescent protein based FRET pairs yet used in biological studies. The developed FRET pairs will be useful for designing FRET based sensors and studies employing Fluorescence Lifetime Imaging Microscopy (FLIM). PMID:26237400

  8. A simple and sensitive UFLC-fluorescence method for endocrine disrupters determination in marine waters.

    PubMed

    Lisboa, Normando S; Fahning, Cristiane S; Cotrim, Gabriel; dos Anjos, Jeancarlo P; de Andrade, Jailson B; Hatje, Vanessa; da Rocha, Gisele O

    2013-12-15

    The present study proposes a fast and simple analytical methodology employing C18 SPE cartridges (for preconcentration and clean-up), and a ultra-fast liquid chromatography coupled to fluorescence detector (UFLC-FLD) for determination of the following endocrine disrupters (ED): bisphenol A (BPA), 4-n-nonylphenol (4NNP), 4-n-octylphenol (4NOP), 4-t-octylphenol (4TOP), estriol (E3), estrone (E1), 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) in seawater. The proposed method was developed, optimized and validated. Separation was done by a total running time of 10 min in a Shim-pack XR-ODS C-18 (2.0 mm ID × 50 mm) chromatographic column, mobile phases were acetonitrile/ultra-pure water under gradient programming; eluent flow rate at 0.120 mL min(-1); column temperature set at 60 °C; emission wavelength of 306 nm and excitation wavelength of 280 nm. The method was validated through assessment of the following parameters: linear range, linearity, selectiveness, precision, recovery test, limit of detection (LOD), and limit of quantification (LOQ). Recoveries ranged from 91% (for EE2) to 104% (for 4NNP) and also was found a suitable repeatability (RSD <4.5%) for all considered compounds. LOD and LOQ ranged from 2.0 ng L(-1) (EE2) to 23 ng L(-1) (E1) and 9.3 ng L(-1) (EE2) to 96 ng L(-1) (E1), respectively. The analytical method using SPE UFLC-FLD was applied to seawater samples collected from Todos os Santos Bay (BTS), Brazil to determine the concentration of eight ED. PMID:24209326

  9. A simple model-free method for direct assessment of fluorescent ligand binding by linear spectral summation.

    PubMed

    Gasymov, Oktay K; Abduragimov, Adil R; Glasgow, Ben J

    2014-01-01

    Fluorescent tagged ligands are commonly used to determine binding to proteins. However, bound and free ligand concentrations are not directly determined. Instead the response in a fluorescent ligand titration experiment is considered to be proportional to the extent of binding and, therefore, the maximum value of binding is scaled to the total protein concentration. Here, a simple model-free method is presented to be performed in two steps. In the first step, normalized bound and free spectra of the ligand are determined. In the second step, these spectra are used to fit composite spectra as the sum of individual components or linear spectral summation. Using linear spectral summation, free and bound 1-Anilinonaphthalene-8-Sulfonic Acid (ANS) fluorescent ligand concentrations are directly calculated to determine ANS binding to tear lipocalin (TL), an archetypical ligand binding protein. Error analysis shows that the parameters that determine bound and free ligand concentrations were recovered with high certainty. The linear spectral summation method is feasible when fluorescence intensity is accompanied by a spectral shift upon protein binding. Computer simulations of the experiments of ANS binding to TL indicate that the method is feasible when the fluorescence spectral shift between bound and free forms of the ligand is just 8 nm. Ligands tagged with environmentally sensitive fluorescent dyes, e.g., dansyl chromophore, are particularly suitable for this method. PMID:24043458

  10. A Simple Model-Free Method for Direct Assessment of Fluorescent Ligand Binding by Linear Spectral Summation

    PubMed Central

    Gasymov, Oktay K.; Abduragimov, Adil R.; Glasgow, Ben J.

    2013-01-01

    Fluorescent tagged ligands are commonly used to determine binding to proteins. However, bound and free ligand concentrations are not directly determined. Instead the response in a fluorescent ligand titration experiment is considered to be proportional to the extent of binding and, therefore, the maximum value of binding is scaled to the total protein concentration. Here, a simple model-free method is presented to be performed in two steps. In the first step, normalized bound and free spectra of the ligand are determined. In the second step, these spectra are used to fit composite spectra as the sum of individual components or linear spectral summation. Using linear spectral summation, free and bound 1-Anilinonaphthalene-8-Sulfonic Acid (ANS) fluorescent ligand concentrations are directly calculated to determine ANS binding to tear lipocalin (TL), an archetypical ligand binding protein. Error analysis shows that the parameters that determine bound and free ligand concentrations were recovered with high certainty. The linear spectral summation method is feasible when fluorescence intensity is accompanied by a spectral shift upon protein binding. Computer simulations of the experiments of ANS binding to TL indicate that the method is feasible when the fluorescence spectral shift between bound and free forms of the ligand is just 8 nm. Ligands tagged with environmentally sensitive fluorescent dyes, e.g., dansyl chromophore, are particularly suitable for this method. PMID:24043458

  11. A reliable non-separation fluorescence quenching assay for total glycated serum protein: a simple alternative to nitroblue tetrazolium reduction.

    PubMed

    Blincko, S; Colbert, D; John, W G; Edwards, R

    2000-05-01

    A simple non-separation assay for the measurement of total glycated serum protein is described. It was found that the fluorescence intensity of a solution of a fluorescein-boronic acid derivative was quenched in proportion to the amount of serum added. This led to the development of an assay in which 10 microL of serum is added to 4 mL of a solution of the fluorescein-boronic acid derivative and the fluorescence intensity is measured after 15 min. The results, as measured by drop in fluorescence intensity, calibrated by a single standard, were compared with the results for nitroblue tetrazolium (NBT) reduction of fructosamine and showed good correlation (r=0.936, n=114). The intra-assay precision (seven samples each measured 10 times) was less than 2.1% (concentration range 190-660 micromol/L); inter-assay precision for seven samples in 10 assays was less than 2.5% (over the same concentration range). Dilution of serum that had a high concentration of total glycated protein showed the assay to be linear. Serum samples (with low, medium and high total glycated protein concentrations) showed less than 2.1% difference from base results with added glucose (up to 60 mmol/L), less than 9.7% difference with added bilirubin (up to 250 micromol/L) and less than 6.9% with added triglycerides (up to 50 mmol/L). Addition of haemoglobin (up to 0.9 g/dL) with high glycation (11.7% HbA1c) to plasma (298 micromol/L total glycated protein) showed less than 10% difference from the base result. Assays performed over a range of temperatures (12-34 degrees C) showed no significant differences in the results. The assay gives similar results to the currently used NTB method but with significantly less susceptibility to interferences. As such the method should be a useful aid in the management of diabetes. PMID:10817254

  12. 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

  13. SIMPLE SURFACE PLASMON RESONANCE-BASED DOSEMETER.

    PubMed

    Urbonavičius, Benas Gabrielis; Adlienė, Diana

    2016-06-01

    The interest to application of various surface plasmon resonance (SPR)-based sensors for the investigation of chemical and biological processes in thin layers deposited on the grating's surface/media is developing. Characterisation of processes as well as specimen's features might be performed analysing variations in optical properties (refraction index) of these thin layers. SPR sensors by default are characterised by high resolution and small uncertainties, and measurements might be performed in situ High-resolution, low-cost, SPR-based dosemeter concept has been proposed and realised depositing dose-sensitive nPAG gel layer onto diffraction grating's surface. The experimental set-up and method for information read out from the sensor were developed and implemented. Obtained results show a potential application of SPR-based dosemeter for dose measurements/mapping in steep gradient fields and/or large area fields. PMID:26535002

  14. A FLUORESCENCE BASED ASSAY FOR DNA DAMAGE: INDUCED BY RADIATION, CHEMICALS AND ENZYMES

    EPA Science Inventory

    A simple and rapid assay to detect DNA damage is reported. This assay is based on the ability of certain dyes to fluoresce upon intercalation with dsDNA. Damage caused by ultraviolet (UV) radiation, chemicals or restriction enzymes is detected using this assay. UV radiation at...

  15. A FLUORESCENCE BASED ASSAY FOR DNA DAMAGE INDUCED BY RADIATION, CHEMICAL MUTAGENS AND ENZYMES

    EPA Science Inventory

    A simple and rapid assay to detect DNA damage is reported. This novel assay is based on changes in melting/annealing behavior and facilitated using certain dyes that increase their fluorescence upon association with double stranded (ds)DNA. Damage caused by ultraviolet (UV) ra...

  16. Development of a fluorescence based flux sensor for thin film growth and nanoparticle deposition.

    PubMed

    De Roo, Bert; Vervaele, Mattias; Rajala, Markku; Miller, Toni; Guillon, Herve; Seo, Jin Won; Locquet, Jean-Pierre

    2016-07-01

    An optical flux sensor, based on the fluorescence properties of materials and nanoparticles, has been developed to control the deposition rate in thin film deposition systems. Using a simple diode laser and a photomultiplier tube with a light filter, we report the detection of gallium atoms and CdSe-ZnS quantum dots. This setup has a high sensitivity and reproducibility. PMID:27475600

  17. 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...

  18. Development of a fluorescence based flux sensor for thin film growth and nanoparticle deposition

    NASA Astrophysics Data System (ADS)

    De Roo, Bert; Vervaele, Mattias; Rajala, Markku; Miller, Toni; Guillon, Herve; Seo, Jin Won; Locquet, Jean-Pierre

    2016-07-01

    An optical flux sensor, based on the fluorescence properties of materials and nanoparticles, has been developed to control the deposition rate in thin film deposition systems. Using a simple diode laser and a photomultiplier tube with a light filter, we report the detection of gallium atoms and CdSe-ZnS quantum dots. This setup has a high sensitivity and reproducibility.

  19. Fluorescent nanoparticles based on AIE fluorogens for bioimaging

    NASA Astrophysics Data System (ADS)

    Yan, Lulin; Zhang, Yan; Xu, Bin; Tian, Wenjing

    2016-01-01

    Fluorescent nanoparticles (FNPs) have recently attracted increasing attention in the biomedical field because of their unique optical properties, easy fabrication and outstanding performance in imaging. Compared with conventional molecular probes including small organic dyes and fluorescent proteins, FNPs based on aggregation-induced emission (AIE) fluorogens have shown significant advantages in tunable emission and brightness, good biocompatibility, superb photo- and physical stability, potential biodegradability and facile surface functionalization. In this review, we summarize the latest advances in the development of fluorescent nanoparticles based on AIE fluorogens including polymer nanoparticles and silica nanoparticles over the past few years, and the various biomedical applications based on these fluorescent nanoparticles are also elaborated.

  20. Two simple micromixers based on silicon

    NASA Astrophysics Data System (ADS)

    Koch, M.; Chatelain, D.; Evans, A. G. R.; Brunnschweiler, A.

    1998-06-01

    This paper reports modelling, fabrication and testing of two micromixers. The principle of mixing used for the devices was diffusion because of the small value of the Reynolds number in microcapillaries. The first mixer separates the main flow into partial flows, which are laterally alternated in order to increase the boundary surface between the liquids. The second mixer superposes two fluids by injection of one liquid into the other. The fabrication technology is based on etching of silicon and anodically bonding with Pyrex glass. The performance of the mixers has been verified by mixing phenolphthalein solution and ammonia dissolved in water. Reasonable mixing was achieved at pressures of around 4 kPa (lateral mixing) and 7 kPa (vertical mixing) with flow rates of approximately 1 0960-1317/8/2/020/img2. The measurements were compared with diffusive mixing simulations with a CFD simulator and agreement of both was observed.

  1. Development of Highly Fluorescent Materials Based on Thiophenylimidazole Dyes

    NASA Technical Reports Server (NTRS)

    Santos, Javier; Bu, Xiu R.; Mintz, Eric A.; Meador, Michael A. (Technical Monitor)

    2000-01-01

    Organic fluorescent materials are expected to find many potential applications in optical devices and photo-functionalized materials. Although many investigations have been focused on heterocyclic compounds such as coumarins, bipyridines, rhodamines, and pyrrole derivatives, little is known for fluorescent imidazole materials. We discovered that one particular class of imidazole derivatives is highly fluorescent. A series of monomeric and polymeric based fluorescent dyes were prepared containing a thiophene unit at the second position of the imidazole ring. Dependence of fluorescence efficiency on parameters such as solvent polarity and substituent groups has been investigated. It was found that a formyl group at the 2-position of the thiophene ring dramatically enhance fluorescence properties. Ion recognition probes indicated their potential as sensor materials. These fluorophores have flexibility for introduction of versatile substituent groups that could improve the fluorescence efficiency and sensor properties.

  2. Green Fluorescent Protein with Anionic Tryptophan-Based Chromophore and Long Fluorescence Lifetime

    PubMed Central

    Sarkisyan, Karen S.; Goryashchenko, Alexander S.; Lidsky, Peter V.; Gorbachev, Dmitry A.; Bozhanova, Nina G.; Gorokhovatsky, Andrey Yu.; Pereverzeva, Alina R.; Ryumina, Alina P.; Zherdeva, Victoria V.; Savitsky, Alexander P.; Solntsev, Kyril M.; Bommarius, Andreas S.; Sharonov, George V.; Lindquist, Jake R.; Drobizhev, Mikhail; Hughes, Thomas E.; Rebane, Aleksander; Lukyanov, Konstantin A.; Mishin, Alexander S.

    2015-01-01

    Spectral diversity of fluorescent proteins, crucial for multiparameter imaging, is based mainly on chemical diversity of their chromophores. Recently we have reported, to our knowledge, a new green fluorescent protein WasCFP—the first fluorescent protein with a tryptophan-based chromophore in the anionic state. However, only a small portion of WasCFP molecules exists in the anionic state at physiological conditions. In this study we report on an improved variant of WasCFP, named NowGFP, with the anionic form dominating at 37°C and neutral pH. It is 30% brighter than enhanced green fluorescent protein (EGFP) and exhibits a fluorescence lifetime of 5.1 ns. We demonstrated that signals of NowGFP and EGFP can be clearly distinguished by fluorescence lifetime in various models, including mammalian cells, mouse tumor xenograft, and Drosophila larvae. NowGFP thus provides an additional channel for multiparameter fluorescence lifetime imaging microscopy of green fluorescent proteins. PMID:26200874

  3. A simple integrated microfluidic device for the multiplexed fluorescence-free detection of Salmonella enterica.

    PubMed

    Strachan, Briony C; Sloane, Hillary S; Houpt, Eric; Lee, Jacob C; Miranian, Daniel C; Li, Jingyi; Nelson, Daniel A; Landers, James P

    2016-02-01

    Rapid, inexpensive and simplistic nucleic acid testing (NAT) is pivotal in delivering biotechnology solutions at the point-of-care (POC). We present a poly(methylmethacrylate) (PMMA) microdevice where on-board infrared-mediated PCR amplification is seamlessly integrated with a particle-based, visual DNA detection for specific detection of bacterial targets in less than 35 minutes. Fluidic control is achieved using a capillary burst valve laser-ablated in a novel manner to confine the PCR reagents to a chamber during thermal cycling, and a manual torque-actuated pressure system to mobilize the fluid from the PCR chamber to the detection reservoir containing oligonucleotide-adducted magnetic particles. Interaction of amplified products specific to the target organism with the beads in a rotating magnetic field allows for near instantaneous (<30 s) detection based on hybridization-induced aggregation (HIA) of the particles and simple optical analysis. The integration of PCR with this rapid, sequence-specific DNA detection method on a single microdevice presents the possibility of creating POC NAT systems that are low cost, easy-to-use, and involve minimal external hardware. PMID:26658961

  4. Disposable nitrate-selective optical sensor based on fluorescent dye

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, disposable thin-film optical nitrate sensor was developed. The sensor was fabricated by applying a nitrate-selective polymer membrane on the surface of a thin polyester film. The membrane was composed of polyvinylchloride (PVC), plasticizer, fluorescent dye, and nitrate-selective ionophore...

  5. Phytoplankton photocompensation from space-based fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Morrison, J. Ruairidh; Goodwin, Deborah S.

    2010-03-01

    Recent satellite-derived observations linked global scale phytoplankton fluorescence variability with iron stress and hinted at photophysiological responses associated with changing light levels. These photocompensation reactions, the sum of photoacclimation and photoadaptation, were examined with climatological data for the Gulf of Maine. Significant seasonal variability was observed in the fluorescence quantum yield that was unrelated to patterns of biomass. Up to 89% of the variability in the fluorescence quantum yield was explained by a physiology-based photocompensation model. Spatial variability in seasonal patterns was associated with differing hydrodynamic regimes. This variability in the quantum yield demonstrates that satellite-based fluorescence is inappropriate for phytoplankton biomass determinations. More importantly, the work presented here provides the modeling foundation for fluorescence-based investigations of temporal and spatial variability in phytoplankton physiology associated with growth irradiance. These space-based physiological observations have the potential to decrease uncertainties in future ocean color derived primary productivity estimates.

  6. 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

  7. A Simple and Effective Ratiometric Fluorescent Probe for the Selective Detection of Cysteine and Homocysteine in Aqueous Media.

    PubMed

    Na, Risong; Zhu, Meiqing; Fan, Shisuo; Wang, Zhen; Wu, Xiangwei; Tang, Jun; Liu, Jia; Wang, Yi; Hua, Rimao

    2016-01-01

    Biothiols such as cysteine (Cys) and homocysteine (Hcy) are essential biomolecules participating in molecular and physiological processes in an organism. However, their selective detection remains challenging. In this study, ethyl 2-(3-formyl-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate (NL) was synthesized as a ratiometric fluorescent probe for the rapid and selective detection of Cys and Hcy over glutathione (GSH) and other amino acids. The fluorescence intensity of the probe in the presence of Cys/Hcy increased about 3-fold at a concentration of 20 equiv. of the probe, compared with that in the absence of these chemicals in aqueous media. The limits of detection of the fluorescent assay were 0.911 μM and 0.828 μM of Cys and Hcy, respectively. ¹H-NMR and MS analyses indicated that an excited-state intramolecular proton transfer is the mechanism of fluorescence sensing. This ratiometric probe is structurally simple and highly selective. The results suggest that it has useful applications in analytical chemistry and diagnostics. PMID:27527138

  8. 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

  9. A simple-structured acridine derivative as a fluorescent enhancement chemosensor for the detection of Pd2+ in aqueous media

    NASA Astrophysics Data System (ADS)

    Zhou, Yanmei; Huang, Qi; Zhang, Qingyou; Min, Yinghao; Wang, Enze

    2015-02-01

    4,5-Bis(hydroxymethyl) acridine (sensor 1) has been discovered and synthesized as a simple-structured Pd2+ fluorescent probe. Sensor 1 showed highly selective recognition toward Pd2+ over other examined metal ions in aqueous solution. Under the optimized condition, fluorescence intensity was linearly proportional to the concentration of Pd2+ in the 0-1 μM concentration range with detection limits of 0.021 μM. The EDTA-adding and stoichiometry experiments indicated that sensor 1 was a reversible chemosensor for Pd2+ with a 2:1 ligand/metal complex at neutral pH. Moreover, the sensor 1 was also successfully applied to determination of Pd2+ in water samples and palladium-containing catalyst, which made it attractive for sensing applications.

  10. Radiative transport-based frequency-domain fluorescence tomography

    NASA Astrophysics Data System (ADS)

    Joshi, Amit; Rasmussen, John C.; Sevick-Muraca, Eva M.; Wareing, Todd A.; McGhee, John

    2008-04-01

    We report the development of radiative transport model-based fluorescence optical tomography from frequency-domain boundary measurements. The coupled radiative transport model for describing NIR fluorescence propagation in tissue is solved by a novel software based on the established Attila™ particle transport simulation platform. The proposed scheme enables the prediction of fluorescence measurements with non-contact sources and detectors at a minimal computational cost. An adjoint transport solution-based fluorescence tomography algorithm is implemented on dual grids to efficiently assemble the measurement sensitivity Jacobian matrix. Finally, we demonstrate fluorescence tomography on a realistic computational mouse model to locate nM to µM fluorophore concentration distributions in simulated mouse organs.

  11. A sensitive fluorescent sensor for selective determination of dichlorvos based on the recovered fluorescence of carbon dots-Cu(II) system.

    PubMed

    Hou, Juying; Dong, Guangjuan; Tian, Zhengbin; Lu, Jiutian; Wang, Qianqian; Ai, Shiyun; Wang, Minglin

    2016-07-01

    In this paper, a simple and sensitive fluorescent sensor for dichlorvos was first constructed based on carbon dots-Cu(II) system. These carbon dots were obtained by simple hydrothermal reaction of feather. The fluorescence of these carbon dots can be selectively quenched by Cu(2+) ion. When acetylcholinesterase and acetylthiocholine were introduced into the system, thiocholine came into being, which can react with Cu(2+) ion and restore the fluorescence of the system. The reaction mechanism between Cu(2+) ion and thiocholine was confirmed by X-ray photoelectron spectroscopy. As one kind of acetylcholinesterase inhibitor, organophosphorus pesticides can be detected based on this sensing system. As an example of organophosphorus pesticides, dichlorvos was detected with a linear range of 6.0×10(-9)-6.0×10(-8)M. This sensing system has been successfully used for the analysis of cabbage and fruit juice samples. PMID:26920268

  12. Eco-friendly carbon-nanodot-based fluorescent paints for advanced photocatalytic systems.

    PubMed

    Park, So Young; Lee, Hyun Uk; Lee, Young-Chul; Choi, Saehae; Cho, Dae Hyun; Kim, Hee Sik; Bang, Sunghee; Seo, Soonjoo; Lee, Soon Chang; Won, Jonghan; Son, Byung-Chul; Yang, Mino; Lee, Jouhahn

    2015-01-01

    Fluorescent carbon nanomaterials, especially zero-dimensional (0D) carbon nanodots (CDs), are widely used in broad biological and optoelectronic applications. CDs have unique characteristics such as strong fluorescence, biocompatibility, sun-light response, and capability of mass-production. Beyond the previous green CD obtained from harmful natural substances, we report a new type of fluid-based fluorescent CD paints (C-paints) derived from polyethylene glycol (PEG; via simple ultrasound irradiation at room temperatures) and produced in quantum yields of up to ~14%. Additionally, C-paints possess a strong, UV- and visible-light-responsive photoluminescent (PL) property. Most especially, C-paints, by incorporation into a photocatalytic system, show additional roles in the emission of fluorescent light for activation of TiO2 nanoparticles (NPs) and the resultant detoxification of most organic dyes, thus further enabling embarkation in advanced water purification. PMID:26201431

  13. Eco-friendly carbon-nanodot-based fluorescent paints for advanced photocatalytic systems

    NASA Astrophysics Data System (ADS)

    Young Park, So; Uk Lee, Hyun; Lee, Young-Chul; Choi, Saehae; Hyun Cho, Dae; Sik Kim, Hee; Bang, Sunghee; Seo, Soonjoo; Chang Lee, Soon; Won, Jonghan; Son, Byung-Chul; Yang, Mino; Lee, Jouhahn

    2015-07-01

    Fluorescent carbon nanomaterials, especially zero-dimensional (0D) carbon nanodots (CDs), are widely used in broad biological and optoelectronic applications. CDs have unique characteristics such as strong fluorescence, biocompatibility, sun-light response, and capability of mass-production. Beyond the previous green CD obtained from harmful natural substances, we report a new type of fluid-based fluorescent CD paints (C-paints) derived from polyethylene glycol (PEG; via simple ultrasound irradiation at room temperatures) and produced in quantum yields of up to ~14%. Additionally, C-paints possess a strong, UV- and visible-light-responsive photoluminescent (PL) property. Most especially, C-paints, by incorporation into a photocatalytic system, show additional roles in the emission of fluorescent light for activation of TiO2 nanoparticles (NPs) and the resultant detoxification of most organic dyes, thus further enabling embarkation in advanced water purification.

  14. Hyperspectral fluorescence microscopy based on compressed sensing

    NASA Astrophysics Data System (ADS)

    Studer, Vincent; Bobin, Jérome; Chahid, Makhlad; Mousavi, Hamed; Candes, Emmanuel; Dahan, Maxime

    2012-03-01

    In fluorescence microscopy, one can distinguish two kinds of imaging approaches, wide field and raster scan microscopy, differing by their excitation and detection scheme. In both imaging modalities the acquisition is independent of the information content of the image. Rather, the number of acquisitions N, is imposed by the Nyquist-Shannon theorem. However, in practice, many biological images are compressible (or, equivalently here, sparse), meaning that they depend on a number of degrees of freedom K that is smaller that their size N. Recently, the mathematical theory of compressed sensing (CS) has shown how the sensing modality could take advantage of the image sparsity to reconstruct images with no loss of information while largely reducing the number M of acquisition. Here we present a novel fluorescence microscope designed along the principles of CS. It uses a spatial light modulator (DMD) to create structured wide field excitation patterns and a sensitive point detector to measure the emitted fluorescence. On sparse fluorescent samples, we could achieve compression ratio N/M of up to 64, meaning that an image can be reconstructed with a number of measurements of only 1.5 % of its pixel number. Furthemore, we extend our CS acquisition scheme to an hyperspectral imaging system.

  15. 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.

  16. Molecular spies for bioimaging--fluorescent protein-based probes.

    PubMed

    Miyawaki, Atsushi; Niino, Yusuke

    2015-05-21

    Convergent advances in optical imaging and genetic engineering have fueled the development of new technologies for biological visualization. Those technologies include genetically encoded indicators based on fluorescent proteins (FPs) for imaging ions, molecules, and enzymatic activities "to spy on cells," as phrased by Roger Tsien, by sneaking into specific tissues, cell types, or subcellular compartments, and reporting on specific intracellular activities. Here we review the current range of unimolecular indicators whose working principle is the conversion of a protein conformational change into a fluorescence signal. Many of the indicators have been developed from fluorescence resonance energy transfer- and single-FP-based approaches. PMID:26000848

  17. Reversible "off-on" fluorescent chemosensor for Hg 2+ based on rhodamine derivative

    NASA Astrophysics Data System (ADS)

    Liu, Weimin; Chen, Jianhong; Xu, Liwei; Wu, Jiasheng; Xu, Haitao; Zhang, Hongyan; Wang, Pengfei

    2012-01-01

    A novel and simple fluorescent chemosensor based on rhodamine was designed and synthesized to detect Hg 2+ with high selectivity. The structure of chemosensor 1 was characterized by IR, 1H NMR, and HRMS spectroscopies. Chemosensor 1 exhibited distinct fluorescent and colorimetric changes toward Hg 2+ in an ethanol/water (80/20, v/v) solution, which resulted in the formation of 1/Hg 2+ complex with the Hg 2+-induced ring opening of the spirolactam ring in rhodamine. The reversibility of chemosensor 1 was verified through its spectral response toward Hg 2+ ions and TBAI (tetrabutylammonium iodide) titration experiments.

  18. Selective recognition iodide in aqueous solution based on fluorescence enhancement chemosensor

    NASA Astrophysics Data System (ADS)

    Lin, Li-Rong; Fang, Wei; Yu, Yun; Huang, Rong-Bin; Zheng, Lan-Sun

    2007-08-01

    A novel and simple fluorescence enhancement method for selectively sensing iodide was proposed based on metal complex formation between mercuric(II) ion with fluorophore ( p-((dimethylamino)benzylidene)thiosemicarbazide, 1) and with anion in aqueous solution. The 1-Hg complex was found to show selectively and sensitively fluorescence enhancement response toward iodide over than S 2-, EDTA, SCN -, CH 3CO 2-, Br -, Cl -, F -, H 2PO 4- and SO 42-, which was attributed to the higher stability of inorganic complex between iodide and mercuric(II).

  19. Cannula-based computational fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Kim, Ganghun; Nagarajan, Naveen; Capecchi, Mario R.; Menon, Rajesh

    2015-06-01

    We converted a solid-glass cannula into a high-resolution widefield fluorescence microscope. Calibrating the space-variant point-spread functions of the cannula and applying a nonlinear optimization algorithm to reconstruct object details enable this development. The resolution of our system is ˜1 μm, and fluorophore position is determined to a precision of ˜20 nm. Images of microglia from fixed slices of mouse brains at various post-natal development stages were also obtained.

  20. 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…

  1. Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions

    NASA Astrophysics Data System (ADS)

    Sharifzadeh, Mohsen; Bernstein, Paul S.; Gellermann, Werner

    2006-10-01

    We have developed a CCD-camera-based nonmydriatic instrument that detects fluorescence from retinal lipofuscin chromophores ("autofluorescence") as a means to indirectly quantify and spatially image the distribution of macular pigment (MP). The lipofuscin fluorescence intensity is reduced at all retinal locations containing MP, since MP has a competing absorption in the blue-green wavelength region. Projecting a large diameter, 488 nm excitation spot onto the retina, centered on the fovea, but extending into the macular periphery, and comparing lipofuscin fluorescence intensities outside and inside the foveal area, it is possible to spatially map out the distribution of MP. Spectrally selective detection of the lipofuscin fluorescence reveals an important wavelength dependence of the obtainable image contrast and deduced MP optical density levels, showing that it is important to block out interfering fluorescence contributions in the detection setup originating from ocular media such as the lens. Measuring 70 healthy human volunteer subjects with no ocular pathologies, we find widely varying spatial extent of MP, distinctly differing distribution patterns of MP, and strongly differing absolute MP levels among individuals. Our population study suggests that MP imaging based on lipofuscin fluorescence is useful as a relatively simple, objective, and quantitative noninvasive optical technique suitable to rapidly screen MP levels and distributions in healthy humans with undilated pupils.

  2. Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions

    PubMed Central

    Sharifzadeh, Mohsen; Bernstein, Paul S.; Gellermann, Werner

    2011-01-01

    We have developed a CCD-camera-based nonmydriatic instrument that detects fluorescence from retinal lipofuscin chromophores (“autofluorescence”) as a means to indirectly quantify and spatially image the distribution of macular pigment (MP). The lipofuscin fluorescence intensity is reduced at all retinal locations containing MP, since MP has a competing absorption in the blue–green wavelength region. Projecting a large diameter, 488 nm excitation spot onto the retina, centered on the fovea, but extending into the macular periphery, and comparing lipofuscin fluorescence intensities outside and inside the foveal area, it is possible to spatially map out the distribution of MP. Spectrally selective detection of the lipofuscin fluorescence reveals an important wavelength dependence of the obtainable image contrast and deduced MP optical density levels, showing that it is important to block out interfering fluorescence contributions in the detection setup originating from ocular media such as the lens. Measuring 70 healthy human volunteer subjects with no ocular pathologies, we find widely varying spatial extent of MP, distinctly differing distribution patterns of MP, and strongly differing absolute MP levels among individuals. Our population study suggests that MP imaging based on lipofuscin fluorescence is useful as a relatively simple, objective, and quantitative noninvasive optical technique suitable to rapidly screen MP levels and distributions in healthy humans with undilated pupils. PMID:16985523

  3. A ratiometric fluorescent quantum dots based biosensor for organophosphorus pesticides detection by inner-filter effect.

    PubMed

    Yan, Xu; Li, Hongxia; Han, Xiaosong; Su, Xingguang

    2015-12-15

    In this work, we develop a novel and sensitive sensor for the detection of organophosphorus pesticides based on the inner-filter effect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent quantum dots (RF-QDs). The RF-QDs has been designed by hybridizing two differently colored CdTe QDs, in which the red emissive QDs entrapped in the silica sphere acting as the reference signal, and the green emissive QDs covalently attached on the silica surface serving as the response signal.The fluorescence of RF-QDs could be quenched by AuNPs based on IFE. Protamine could effectively turn on the fluorescence due to the electrostatic attraction between protamine and AuNPs. Trypsin can easily hydrolyze protamine, leading to the quench of the fluorescence. Then, the fluorescence could be recovered again by the addition of parathion-methyl (PM) which could inhibit the activity of trypsin. By measuring the fluorescence of RF-QDs, the inhibition efficiency of PM to trypsin activity was evaluated. Under the optimized conditions, the inhibition efficiency was proportional to the logarithm of PM concentration in the range of 0.04-400 ng mL(-1), with a detection limit of 0.018 ng mL(-1). Furthermore, the simple and convenient method had been used for PM detection in environmental and agricultural samples with satisfactory results. PMID:26143468

  4. Innovative molecular-based fluorescent nanoparticles for multicolor single particle tracking in cells

    NASA Astrophysics Data System (ADS)

    Daniel, Jonathan; Godin, Antoine G.; Palayret, Matthieu; Lounis, Brahim; Cognet, Laurent; Blanchard-Desce, Mireille

    2016-03-01

    Based on an original molecular-based design, we present bright and photostable fluorescent organic nanoparticles (FONs) showing excellent colloidal stability in various aqueous environments. Complementary near-infrared emitting and green emitting FONs were prepared using a simple, fast and robust protocol. Both types of FONs could be simultaneously imaged at the single-particle level in solution as well as in biological environments using a monochromatic excitation and a dual-color fluorescence microscope. No evidence of acute cytotoxicity was found upon incubation of live cells with mixed solutions of FONs, and both types of nanoparticles were found internalized in the cells where their motion could be simultaneously tracked at video-rate up to minutes. These fluorescent organic nanoparticles open a novel non-toxic alternative to existing nanoparticles for imaging biological structures, compatible with live-cell experiments and specially fitted for multicolor single particle tracking.

  5. Fluorescence biosensing strategy based on energy transfer between fluorescently labeled receptors and a metallic surface.

    PubMed

    Pérez-Luna, Víctor H; Yang, Saipeng; Rabinovich, Emmanuil M; Buranda, Tione; Sklar, Larry A; Hampton, Philip D; López, Gabriel P

    2002-01-01

    A new fluorescence-based biosensor is presented. The biosensing scheme is based on the fact that a fluorophore in close proximity to a metal film (<100 A) experiences strong quenching of fluorescence and a dramatic reduction in the lifetime of the excited state. By immobilizing the analyte of interest (or a structural analog of the analyte) to a metal surface and exposing it to a labeled receptor (e.g. antibody), the fluorescence of the labeled receptor becomes quenched upon binding because of the close proximity to the metal. Upon exposure to free analyte, the labeled receptor dissociates from the surface and diffuses into the bulk of the solution. This increases its separation from the metal and an increase of fluorescence intensity and/or lifetime of the excited state is observed that indicates the presence of the soluble analyte. By enclosing this system within a small volume with a semipermeable membrane, a reversible device is obtained. We demonstrate this scheme using a biotinylated self-assembled monolayer (SAM) on gold as our surface immobilized analyte analog, fluorescently labeled anti-biotin as a receptor, and a solution of biotin in PBS as a model analyte. This scheme could easily be extended to transduce a wide variety of protein-ligand interactions and other biorecognition phenomena (e.g. DNA hybridization) that result in changes in the architecture of surface immobilized biomolecules such that a change in the separation distance between fluorophores and the metal film is obtained. PMID:11742737

  6. 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…

  7. 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.

  8. Simple refractometer based on in-line fiber interferometers

    NASA Astrophysics Data System (ADS)

    Esteban, Ó.; Martínez Manuel, R.; Shlyagin, M. G.

    2015-09-01

    A very simple but accurate optical fiber refractometer based on the Fresnel reflection in the fiber tip and two in-line low-reflective mirrors for light intensity referencing is reported. Each mirror was generated by connecting together 2 fiber sections with FC/PC and FC/APC connectors using the standard FC/PC mating sleeve. For the sensor interrogation, a standard DFB diode laser pumped with a sawtooth-wave current was used. A resolution of 6 x 10-4 was experimentally demonstrated using different liquids. A simple sensor construction and the use of low cost components make the reported system interesting for many applications.

  9. Simple, rapid detection of influenza A (H1N1) viruses using a highly sensitive peptide-based molecular beacon.

    PubMed

    Lim, Eun-Kyung; Guk, Kyeonghye; Kim, Hyeran; Chung, Bong-Hyun; Jung, Juyeon

    2016-01-01

    A peptide-based molecular beacon (PEP-MB) was prepared for the simple, rapid, and specific detection of H1N1 viruses using a fluorescence resonance energy transfer (FRET) system. The PEP-MB exhibited minimal fluorescence in its "closed" hairpin structure. However, in the presence of H1N1 viruses, the specific recognition of the hemagglutinin (HA) protein of H1 strains by the PEP-MB causes the beacon to assume an "open" structure that emits strong fluorescence. The PEP-MB could detect H1N1 viruses within 15 min or even 5 min and can exhibit strong fluorescence even at low viral concentrations, with a detection limit of 4 copies. PMID:26509476

  10. 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.

  11. A simple Chalcone-based ratiometric chemosensor for silver ion.

    PubMed

    Velmurugan, K; Suresh, S; Santhoshkumar, S; Saranya, M; Nandhakumar, R

    2016-05-01

    Herein, we report the selective binding of Ag(+) ion by the anthracene-based chalcone receptor 1. Receptor 1 behaves as a selective and sensitive chemosensor for the recognition of Ag(+) over other heavy and transition metal ions without any interference and is capable of detecting the metal ion down to 0.15 × 10(-6) M. Receptor 1 on binding with Ag(+) ions exhibits a ratiometric fluorescence enhancement, which is due to the inhibition of photoinduced electron transfer along with the intramolecular charge transfer mechanism. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26333533

  12. A graphene oxide-peptide fluorescence sensor tailor-made for simple and sensitive detection of matrix metalloproteinase 2.

    PubMed

    Feng, Duan; Zhang, Yangyang; Feng, Tingting; Shi, Wen; Li, Xiaohua; Ma, Huimin

    2011-10-14

    A graphene oxide-peptide based fluorescence sensor has been developed for matrix metalloproteinase 2 (MMP2), and its applicability has been demonstrated by monitoring the concentration of MMP2 secreted by HeLa cells, revealing that HeLa cells with a density of 5.48 × 10(5) cells per mL can produce 22 nM in cell culture media in 24 h. PMID:21892449

  13. Radioiodine detector based on laser induced fluorescence

    DOEpatents

    McDonald, Jimmie R.; Baronavski, Andrew P.

    1980-01-01

    The invention involves the measurement of the concentration of the radioisotope .sup.129 I.sub.2 in the presence of a gas. The invention uses a laser to excite a sample of the .sup.129 I.sub.2 in a sample gas chamber and a reference sample of a known concentration of .sup.129 I.sub.2 in a reference gas chamber. The .sup.129 I.sub.2 in the sample and reference gas chamber each gives off fluorescence emissions which are received by photomultipliers which provide signals to a detector. The detector uses a ratioing technique to determine the concentration of .sup.129 I.sub.2 in the sample gas chamber.

  14. A simple turn on fluorescent sensor for the selective detection of thiamine using coconut water derived luminescent carbon dots.

    PubMed

    Purbia, Rahul; Paria, Santanu

    2016-05-15

    In this study microwave-assisted hydrothermal method was used to prepare highly luminescent carbon dots (1-6 nm size) within a minute from tender coconut (Cocos nucifera) water. The synthesized carbon dots (C-dots) exhibit emission of blue and green lights while excited at 390 and 450 nm wavelengths, respectively. As an application, these C-dots were tested for a simple "turn on" fluorescent sensor for rapid detection of thiamine (vitamin B1). The detection of thiamine in human body is very important to prevent various diseases such as beriberi, neurological disorders, optic neuropathy, etc. The fluorescence emission intensity of C-dots quenches after addition of Cu(2+) ion and then again increases selectively (turn on) after the addition of thiamine. The fluorescence emission intensity enhancement of Cu(2+) ion modified C-dots in the presence of thiamine exhibits a linear relationship within the thiamine concentration range of 10-50 μM. The limit of detection was found to be 280 nM from this study. The selectivity of the detection was also tested in the presence of different organic molecules and inorganic ions (Ca(2+), Mg(2+), Na(+), K(+), Cl(-), SO4(2-), and NO3(-)) which are present in blood serum and urine and found to be almost no interference in the detection. Finally, to see the applicability in real samples a commercial vitamin capsule was tested and found less than 3% error in the detected concentration. The C-dots were also used for bioimaging of fungus and the results show they are also suitable for this application too. PMID:26745793

  15. A homogeneous fluorescence-based method to measure antibody internalization in tumor cells.

    PubMed

    Gong, Haibiao; Urlacher, Teresa

    2015-01-15

    We have developed a simple fluorescence-based method to monitor antibody internalization. Panitumumab was dual-labeled with the fluorophore IRDye 800CW and quencher IRDye QC-1 to yield the biomolecular probe Pan800QC. The fluorescence of IRDye 800CW is quenched by IRDye QC-1 on the same intact antibody. After incubation with epidermal growth factor receptor (EGFR)-expressing cells, internalization of Pan800QC was detected by an increase in fluorescence signal due to enzymatic digestion of the antibody and separation of IRDye 800CW and IRDye QC-1. By optimizing reaction conditions, a signal-to-background ratio of 8.5 was obtained. This homogeneous assay can be applied in the characterization and screening of internalizing antibodies. PMID:25245185

  16. Visual and fluorescent detection of acetamiprid based on the inner filter effect of gold nanoparticles on ratiometric fluorescence quantum dots.

    PubMed

    Yan, Xu; Li, Hongxia; Li, Yang; Su, Xingguang

    2014-12-10

    In this work, we develop a simple and rapid sensing method for the visual and fluorescent detection of acetamiprid (AC) based on the inner-filter effect (IFE) of gold nanoparticles (AuNPs) on ratiometric fluorescent quantum dots (RF-QDs). The RF-QDs based dual-emission nanosensor was fabricated by assembling green emissive QDs (QDs539nm, λem=539 nm) on the surface of red emissive QDs (QDs661nm, λem=661 nm)-doped silica microspheres. The photoluminescence (PL) intensity of RF-QDs could be quenched by AuNPs based on IFE. Acetamiprid can adsorb on the surface of AuNPs due to its cyano group that has good affinity with gold, which could induce the aggregation of AuNPs accompanying color change from red to blue. Thus, the IFE of AuNPs on RF-QDs was weakened and the PL intensity of RF-QDs was recovered accordingly. Under the optimized conditions, the PL intensity of the RF-QDs/AuNPs system was proportional to the concentration of AC in the range of 0.025-5.0 μg mL(-1), with a detection limit of 16.8 μg L(-1). The established method had been used for AC detection in environmental and agricultural samples with satisfactory results. PMID:25441897

  17. Simple method of DNA stretching on glass substrate for fluorescence image and spectroscopy

    NASA Astrophysics Data System (ADS)

    Neupane, Guru P.; Dhakal, Krishna P.; Lee, Hyunsoo; Guthold, Martin; Joseph, Vincent S.; Hong, Jong-Dal; Kim, Jeongyong

    2013-05-01

    Study of biological molecule DNA has contributed to developing many breaking thoughts and wide applications in multidisciplinary fields, such as genomic, medical, sensing and forensic fields. Stretching of DNA molecules is an important supportive tool for AFM or spectroscopic studies of DNA in a single molecular level. In this article, we established a simple method of DNA stretching (to its full length) that occurred on a rotating negatively-charged surface of glass substrate. The isolation of a single DNA molecule was attained by the two competitive forces on DNA molecules, that is, the electrostatic attraction developed between the positively charged YOYO-1 stained DNA and the negatively charged substrate, and the centrifugal force of the rotating substrate, which separates the DNA aggregates into the single molecule. Density of stretched DNA molecules was controlled by selecting the specific parameters such as spinning time and rates, loading volume of DNA-dye complex solution etc. The atomic force microscopy image exhibited a single DNA molecule on the negatively-charged substrate in an isolated state. Further, the photoluminescence spectra of a single DNA molecule stained with YOYO-1 were achieved using the method developed in the present study, which is strongly believed to effectively support the spectroscopic analysis of DNA in a single molecular level.

  18. Photophysical properties of pyrrolocytosine, a cytosine fluorescent base analogue.

    PubMed

    Nguyen, Quynh L; Spata, Vincent A; Matsika, Spiridoula

    2016-07-27

    The photophysical behavior of pyrrolocytosine (PC), a fluorescent base analogue of cytosine, has been investigated using theoretical approaches. The similarities between the PC and cytosine structures allow PC to maintain the pseudo-Watson-Crick base-pairing arrangement with guanine. Cytosine, similar to the other natural nucleobases, is practically non-fluorescent, because of ultrafast radiationless decay occurring through conical intersections. PC displays a much higher fluorescence quantum yield than cytosine, making it an effective fluorescent marker to study the structure, function, and dynamics of DNA/RNA complexes. Similar to 2-aminopurine, a constitutional isomer of adenine that base-pairs with thymine, PC's fluorescence is quenched when it is incorporated into a dinucleotide or a trinucleotide. In this work we examine the photophysical properties of isolated PC, microhydrated PC, as well as, complexes where PC is either base-stacked or hydrogen-bonded with guanine. Our results indicate that hydration affects the radiationless decay pathways in PC by destabilizing conical intersections. The calculations of dimers and trimers show that the radiative decay is affected by π stacking, while the presence of charge transfer states between PC and guanine may contribute to radiationless decay. PMID:27251599

  19. Cobalt oxyhydroxide nanoflake based fluorescence sensing platform for label-free detection of DNA.

    PubMed

    Chang, Yaqing; Zhang, Zhe; Liu, Huiqing; Wang, Nan; Tang, Jilin

    2016-08-01

    Detection of specific DNA sequences is critical in life science. In this study, we investigated the interaction of cobalt oxyhydroxide (CoOOH) nanoflakes with DNA and their fluorescence quenching mechanism of a FAM-labeled single-stranded DNA (ssDNA) probe. ssDNA could adsorb on the CoOOH surface via electrostatic interactions and therefore the fluorescence of FAM was quenched. However, upon addition of targets, ssDNA was hybridized with target DNA and the formed double-stranded DNA (dsDNA) had much weaker affinity to CoOOH, resulting in the retaining of fluorescence. Based on the affinity difference of CoOOH nanoflakes to ssDNA and dsDNA and fluorescence resonance energy transfer based fluorescence quenching, a mix-and-detect method was proposed for homogeneous detection of DNA. The proposed method is simple and can be finished in a few minutes with high sensitivity. Furthermore, it displays a wide linear range from 1 to 50 nM with a detection limit of 0.5 nM and is capable of detecting DNA in real biological samples. PMID:27251111

  20. Red Fluorescent Carbon Nanoparticle-Based Cell Imaging Probe.

    PubMed

    Ali, Haydar; Bhunia, Susanta Kumar; Dalal, Chumki; Jana, Nikhil R

    2016-04-13

    Fluorescent carbon nanoparticle-based probes with tunable visible emission are biocompatible, environment friendly and most suitable for various biomedical applications. However, synthesis of red fluorescent carbon nanoparticles and their transformation into functional nanoparticles are very challenging. Here we report red fluorescent carbon nanoparticle-based nanobioconjugates of <25 nm hydrodynamic size and their application as fluorescent cell labels. Hydrophobic carbon nanoparticles are synthesized via high temperature colloid-chemical approach and transformed into water-soluble functional nanoparticles via coating with amphiphilic polymer followed by covalent linking with desired biomolecules. Following this approach, carbon nanoparticles are functionalized with polyethylene glycol, primary amine, glucose, arginine, histidine, biotin and folic acid. These functional nanoparticles can be excited with blue/green light (i.e., 400-550 nm) to capture their emission spanning from 550 to 750 nm. Arginine and folic acid functionalized nanoparticles have been demonstrated as fluorescent cell labels where blue and green excitation has been used for imaging of labeled cells. The presented method can be extended for the development of carbon nanoparticle-based other bioimaging probes. PMID:27011336

  1. Simple super-resolution live-cell imaging based on diffusion-assisted Förster resonance energy transfer

    PubMed Central

    Cho, Sangyeon; Jang, Jaeduck; Song, Chaeyeon; Lee, Heeyoung; Ganesan, Prabhakar; Yoon, Tae-Young; Kim, Mahn Won; Choi, Myung Chul; Ihee, Hyotcherl; Heo, Won Do; Park, YongKeun

    2013-01-01

    Despite the recent development of several super-resolution fluorescence microscopic techniques, there are still few techniques that can be readily employed in conventional imaging systems. We present a very simple, rapid, general and cost-efficient super-resolution imaging method, which can be directly employed in a simple fluorescent imaging system with general fluorophores. Based on diffusion-assisted Förster resonance energy transfer (FRET), fluorescent donor molecules that label specific target structures can be stochastically quenched by diffusing acceptor molecules, thereby temporally separating otherwise spatially overlapped fluorescence signals and allowing super-resolution imaging. The proposed method provides two- to three-fold-enhancement in spatial resolution, a significant optical sectioning property, and favorable temporal resolution in live-cell imaging. We demonstrate super-resolution live-cell dynamic imaging using general fluorophores in a standard epi-fluorescence microscope with light-emitting diode (LED) illumination. Due to the simplicity of this approach, we expect that the proposed method will prove an attractive option for super-resolution imaging. PMID:23383376

  2. 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 τ1=0.28ns and τ2=0.60ns (representing free NADH) and the longer lifetime of τ3=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.

  3. A Simple Fluorescence Quenching Method for the Determination of Vanillin Using TGA-capped CdTe/ZnS Nanoparticles as Probes.

    PubMed

    Li, Li; Zhang, Qiaolin; Ding, Yaping; Lu, Yaxiang; Cai, Xiaoyong; Yu, Lurong

    2015-07-01

    Based on the quenching of the fluorescence intensity of thioglycolic acid (TGA)-capped core-shell CdTe/ZnS nanoparticles (NPs) by vanillin, a novel, simple and rapid method for the determination of vanillin was proposed. In aqueous medium, the functionalized core-shell CdTe/ZnS NPs were successfully synthesized with TGA as the capping ligand. TGA-capped core-shell CdTe/ZnS NPs were characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. Factors affecting the vanillin detection were investigated, and the optimum conditions were also determined. Under the optimum conditions, the relative fluorescence intensity of CdTe/ZnS NPs was linearly proportional to vanillin over a concentration range from 9.4 × 10(-7) to 5.2 × 10(-4) M with a correlation coefficient of 0.998 and a detection limit of 2.6 × 10(-7) M. The proposed method was also employed to detect trace vanillin in cookies with satisfactory results. PMID:25911548

  4. A virus-MIPs fluorescent sensor based on FRET for highly sensitive detection of JEV.

    PubMed

    Liang, Caishuang; Wang, Huan; He, Kui; Chen, Chunyan; Chen, Xiaoming; Gong, Hang; Cai, Changqun

    2016-11-01

    Major stumbling blocks in the recognition and detection of virus are the unstable biological recognition element or the complex detection means. Here a fluorescent sensor based on virus-molecular imprinted polymers (virus-MIPs) was designed for specific recognition and highly sensitive detection of Japanese encephalitis virus (JEV). The virus-MIPs were anchored on the surface of silica microspheres modified by fluorescent dye, pyrene-1-carboxaldehyde (PC). The fluorescence intensity of PC can be enhanced by the principle of fluorescence resonance energy transfer (FRET), where virus acted as energy donor and PC acted as energy acceptor. The enhanced fluorescence intensity was proportional to the concentration of virus in the range of 24-960pM, with a limit of detection (LOD, 3σ) of 9.6pM, and the relative standard deviation was 1.99%. In additional, the specificity study confirmed the resultant MIPs has high-selectivity for JEV. This sensor would become a new key for the detection of virus because of its high sensitive, simple operation, high stability and low cost. PMID:27591625

  5. A Cell-Based Fluorescent Assay to Detect the Activity of Shiga Toxin and Other Toxins That Inhibit Protein Synthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli O157:H7, a major cause of food-borne illness, produces Shiga toxins that block protein synthesis by inactivating the ribosome. In this chapter we describe a simple cell-based fluorescent assay to detect Shiga toxins and inhibitors of toxin activity. The assay can also be used to d...

  6. Performance validation of EMCCD and ICCD based near-infrared fluorescence imaging systems on a fluorescence solid phantom

    NASA Astrophysics Data System (ADS)

    Zhu, Banghe; Sevick-Muraca, Eva M.

    2012-03-01

    Near infrared (NIR) fluorescence imaging has been successfully applied for non-invasive assessment of both lymphatic architecture and function as well as potential disease markers of lymphatic dysfunction in clinical studies with intradermal injection of indocyanine green (ICG). For new "first-in-humans" NIR fluorescence imaging agents that need to be employed at far lower quantities, NIR fluorescence imaging devices with high measurement sensitivity are most favorable. However, the measurement sensitivity of NIR fluorescence imaging devices is limited by various parameters, including quantum efficiency of CCD chip, noise sources in the CCD camera, and the leakage of excitation light through optical filters. In this contribution, we present a quantum dot-based fluorescence solid phantom and its use for characterization of excitation light leakage and measurement sensitivity in both the intensified CCD (ICCD) and Electron Multiplying CCD (EMCCD) based NIR fluorescence imaging devices. The stability of the constructed quantum dot-based fluorescence solid phantom was first demonstrated and used to demonstrate higher measurement sensitivity compared of the ICCD as opposed to the EMCCD based NIR fluorescence imaging device when integration time were maintained less than 1.0 s. The phantom was used to assess the calculated transmission ratio, R, to minimize noise owing to excitation light leakage and show optimized filtering capabilities. The constructed quantum dot based solid phantom and the methodology for measuring parameters of transmission ratio and SNR can be used as a standard and quantifiable metric for installation and operational qualification of all NIR fluorescence imaging devices.

  7. VCSEL-based flexible opto-fluidic fluorescence sensors

    NASA Astrophysics Data System (ADS)

    Kang, Dongseok; Gai, Boju; Yoon, Jongseung

    2016-03-01

    Flexible opto-fluidic fluorescence sensors based on microscale vertical cavity surface emitting lasers (micro-VCSELs) and silicon photodiodes (Si-PDs) are demonstrated, where arrays of 850 nm micro-VCSELs and thin film Si-PDs are heterogeneously integrated on a polyethylene terephthalate (PET) substrate by transfer printing, in conjunction with elastomeric fluidic channel. Enabled with optical isolation trenches together with wavelength- and angle-selective spectral filters implemented to suppress the absorption of excitation light, the integrated flexible fluorescence sensors exhibited significantly enhanced signal-to-background ratio, resulting in a maximum sensitivity of 5 × 10-5 wt% of infrared-absorbing organic dyes.

  8. Fluorescent blood glucose monitor by hemin-functionalized graphene quantum dots based sensing system.

    PubMed

    He, Yuezhen; Wang, Xiaoxun; Sun, Jian; Jiao, Shoufeng; Chen, Hongqi; Gao, Feng; Wang, Lun

    2014-01-31

    In the present work, a highly sensitive and specific fluorescent biosensor for blood glucose monitoring is developed based on hemin-functionalized graphene quantum dots (GQDs) and glucose oxidase (GOx) system. The GQDs which are simply prepared by pyrolyzing citric acid exhibit strong fluorescence and good water-solubility. Due to the noncovalent assembly between hemin and GQDs, the addition of hemin can make hydrogen peroxide (H2O2) to destroy the passivated surface of GQDs, leading to significant fluorescence quenching of GQDs. Based on this effect, a novel fluorescent platform is proposed for the sensing of glucose. Under the optimized conditions, the linear range of glucose is from 9 to 300μM, and the limit of detection is 0.1μM. As unique properties of GQDs, the proposed biosensor is green, simple, cost-efficient, and it is successfully applied to the determination of glucose in human serum. In addition, the proposed method provides a new pathway to further design the biosensors based on the assembly of GQDs with hemin for detection of biomolecules. PMID:24439507

  9. Fluorescence based explosive detection: from mechanisms to sensory materials.

    PubMed

    Sun, Xiangcheng; Wang, Ying; Lei, Yu

    2015-11-21

    The detection of explosives is one of the current pressing concerns in global security. In the past few decades, a large number of emissive sensing materials have been developed for the detection of explosives in vapor, solution, and solid states through fluorescence methods. In recent years, great efforts have been devoted to develop new fluorescent materials with various sensing mechanisms for detecting explosives in order to achieve super-sensitivity, ultra-selectivity, as well as fast response time. This review article starts with a brief introduction on various sensing mechanisms for fluorescence based explosive detection, and then summarizes in an exhaustive and systematic way the state-of-the-art of fluorescent materials for explosive detection with a focus on the research in the recent 5 years. A wide range of fluorescent materials, such as conjugated polymers, small fluorophores, supramolecular systems, bio-inspired materials and aggregation induced emission-active materials, and their sensing performance and sensing mechanism are the centerpiece of this review. Finally, conclusions and future outlook are presented and discussed. PMID:26335504

  10. Optical fiber sensor for nitroaromatic explosives based on fluorescence quenching

    NASA Astrophysics Data System (ADS)

    Chu, Fenghong

    2010-10-01

    The detection of explosives and related compounds is important in both forensic and environmental applications. In this paper, we report on the preparation of novel plastic optical fiber explosive sensor based on fluorescence quenching. A low priced LED light source and PIN detector were used in this sensor system, a U-shaped plastic optical fiber with high sensitivity act as sensor head. We use amplifying fluorescent polymers (AFP) MEH-PPV as fluorescence indictor. MEHPPV was dip coated on to the surface of the U-shaped plastic optical fiber. For the first time as far as we know we detected the fluorescence lifetime by the phase-fluorometry method to measure the concentration of TNT, which has a merit of immunity to fluctuation of the light source and is more reliable than measuring intensity alone. In the experimental set-up the phase shift between excitation light and fluorescence is calculated by correlation method. Two degree phase difference was measured when the sensor head was exposed to TNT vapor and air in primary experiments.

  11. Magnetite nanoparticles for biosensor model based on bacteria fluorescence

    NASA Astrophysics Data System (ADS)

    Poita, A.; Creanga, D.-E.; Airinei, A.; Tupu, P.; Goiceanu, C.; Avadanei, O.

    2009-06-01

    Fluorescence emission of pyoverdine - the siderophore synthesized by iron scavenger bacteria - was studied using in vitro cultures of Pseudomonas aeruginosa with the aim to design a biosensor system for liquid sample iron loading. Diluted suspensions of colloidal magnetite nanoparticles were supplied in the culture medium (10 microl/l and 100 microl/l) to simulate magnetic loading with iron oxides of either environmental waters or human body fluids. The electromagnetic exposure to radiofrequency waves of bacterial samples grown in the presence of magnetic nanoparticles was also carried out. Cell density diminution but fluorescence stimulation following 10 microl/l ferrofluid addition and simultaneous exposure to radiofrequency waves was evidenced. The inhibitory influence of 100 microl/l ferrofluid combined with RF exposure was evidenced by fluorescence data. Mathematical model was proposed to approach quantitatively the dynamics of cell density and fluorescence emission in relation with the consumption of magnetite nanoparticle supplied medium. The biosensor scheme was shaped based on the response to iron loading of bacterial sample fluorescence.

  12. Advanced Fluorescence Protein-Based Synapse-Detectors.

    PubMed

    Lee, Hojin; Oh, Won Chan; Seong, Jihye; Kim, Jinhyun

    2016-01-01

    The complex information-processing capabilities of the central nervous system emerge from intricate patterns of synaptic input-output relationships among various neuronal circuit components. Understanding these capabilities thus requires a precise description of the individual synapses that comprise neural networks. Recent advances in fluorescent protein engineering, along with developments in light-favoring tissue clearing and optical imaging techniques, have rendered light microscopy (LM) a potent candidate for large-scale analyses of synapses, their properties, and their connectivity. Optically imaging newly engineered fluorescent proteins (FPs) tagged to synaptic proteins or microstructures enables the efficient, fine-resolution illumination of synaptic anatomy and function in large neural circuits. Here we review the latest progress in fluorescent protein-based molecular tools for imaging individual synapses and synaptic connectivity. We also identify associated technologies in gene delivery, tissue processing, and computational image analysis that will play a crucial role in bridging the gap between synapse- and system-level neuroscience. PMID:27445785

  13. Advanced Fluorescence Protein-Based Synapse-Detectors

    PubMed Central

    Lee, Hojin; Oh, Won Chan; Seong, Jihye; Kim, Jinhyun

    2016-01-01

    The complex information-processing capabilities of the central nervous system emerge from intricate patterns of synaptic input-output relationships among various neuronal circuit components. Understanding these capabilities thus requires a precise description of the individual synapses that comprise neural networks. Recent advances in fluorescent protein engineering, along with developments in light-favoring tissue clearing and optical imaging techniques, have rendered light microscopy (LM) a potent candidate for large-scale analyses of synapses, their properties, and their connectivity. Optically imaging newly engineered fluorescent proteins (FPs) tagged to synaptic proteins or microstructures enables the efficient, fine-resolution illumination of synaptic anatomy and function in large neural circuits. Here we review the latest progress in fluorescent protein-based molecular tools for imaging individual synapses and synaptic connectivity. We also identify associated technologies in gene delivery, tissue processing, and computational image analysis that will play a crucial role in bridging the gap between synapse- and system-level neuroscience. PMID:27445785

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

    PubMed

    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

  15. 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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, rapid, and high-throughput fluorescent polarization immunoassay (FPIA) for simultaneous determination of organophosphorus pesticides (OPs) was developed. Three haptens were labeled with a fluorescein probe and used as tracers to develop a homogenous FPIA using a broad-specificity monoclon...

  17. Simple, Rapid Mycobacterium ulcerans Disease Diagnosis from Clinical Samples by Fluorescence of Mycolactone on Thin Layer Chromatography

    PubMed Central

    Wadagni, Anita; Frimpong, Michael; Phanzu, Delphin Mavinga; Ablordey, Anthony; Kacou, Emmanuel; Gbedevi, Mirabelle; Marion, Estelle; Xing, Yalan; Babu, Vaddela Sudheer; Phillips, Richard Odame; Wansbrough-Jones, Mark; Kishi, Yoshito; Asiedu, Kingsley

    2015-01-01

    Introduction Mycobacterium ulcerans infection, known as Buruli ulcer, is a disease of the skin and subcutaneous tissues which is an important but neglected tropical disease with its major impact in rural parts of West and Central Africa where facilities for diagnosis and management are poorly developed. We evaluated fluorescent thin layer chromatography (f-TLC) for detection of mycolactone in the laboratory using samples from patients with Buruli ulcer and patients with similar lesions that gave a negative result on PCR for the IS2404 repeat sequence of M. ulcerans Methodology/Principal findings Mycolactone and DNA extracts from fine needle aspiration (FNA), swabs and biopsy specimen were used to determine the sensitivity and specificity of f-TLC when compared with PCR for the IS2404. For 71 IS2404 PCR positive and 28 PCR negative samples the sensitivity was 73.2% and specificity of 85.7% for f-TLC. The sensitivity was similar for swabs (73%), FNAs (75%) and biopsies (70%). Conclusions We have shown that mycolactone can be detected from M. ulcerans infected skin tissue by f-TLC technique. The technique is simple, easy to perform and read with minimal costs. In this study it was undertaken by a member of the group from each endemic country. It is a potentially implementable tool at the district level after evaluation in larger field studies. PMID:26583925

  18. The development of simple and sensitive small-molecule fluorescent probes for the detection of serum proteins after native polyacrylamide gel electrophoresis.

    PubMed

    Wang, Fangfang; Huang, Lingyun; Na, Na; He, Dacheng; Sun, Dezhi; Ouyang, Jin

    2012-05-21

    In this paper, a simple and sensitive small-molecule fluorescent probe, 2,5-dihydroxy-4'-dimethylaminochalcone (DHDMAC), was designed and synthesized for the detection of human serum proteins via hydrophobic interactions after polyacrylamide gel electrophoresis (PAGE). This probe produced lower fluorescence emission in the absence of proteins, and the emission intensity was significantly increased after the interaction with serum proteins. To demonstrate the imaging performance of this probe as a fluorescent dye, a series of experiments was conducted that included sensitivity comparison and 2D-PAGE. The results indicated that the sensitivity of DHDMAC staining is comparable to that of the most widely used fluorescent dye, SYPRO Ruby, and more protein spots (including thyroxine-binding globulin, angiotensinogen, afamin, zinc-α-2-glycoprotein and α-1-antichymotrypsin) were detected after 2D-PAGE. Therefore, DHDMAC is a good protein reporter due to its fast staining procedure, low detection limits and high resolution. PMID:22475746

  19. A fluorescence-based assay for Core 1 β3galactosyltransferase (T-synthase) activity.

    PubMed

    Ju, Tongzhong; Cummings, Richard D

    2013-01-01

    Mucin-type O-glycans on glycoproteins in animal cells play important roles in many biological processes. Core 1 β3galactosyltransferase (Core 1 β3GalT, T-synthase) is a key enzyme in the O-glycan biosynthetic pathway. Emerging evidence has shown the importance of O-glycans and the absolute requirement of T-synthase in this pathway. The assessment of the T-synthase activity has historically been conducted using a radioactive method. Here we describe a fluorescence-based assay procedure for T-synthase activity. T-synthase utilizes the acceptor substrate 4-methylumbelliferone-α-GalNAc (GalNAcα-(4-MU)) and the donor substrate UDP-Gal to synthesize the disaccharide product Galβ1,3GalNAcα-(4-MU) structure. This product is specifically hydrolyzed by endo-α-N-acetylgalactosaminidase (O-glycosidase) releasing free 4-MU. Free 4-MU is highly fluorescent at pH 9.6-10 and can be easily measured by a fluorescent detector (Ex: 355 nm; Em: 460 nm). This fluorescence-based T-synthase assay is simple, sensitive, reproducible, not affected by enzyme source, and adaptable for high-throughput assays. PMID:23765650

  20. The Fluorescence Enhancement of Mercury Detected in Food Based on Rhodamine Derivatives.

    PubMed

    Fan, Cai-ling; Xie, Pu-hui; Cui, Shu-min; Yang, Li-na; Sun, Qing; Ai, Zhi-lu

    2015-05-01

    Recently, the problem of food security is more and more serious, and people pay attention to mercury because of the toxic of it. A new approach for the determination of mercury content in foodstuff is devised. In this paper, first, we design and synthesis a new kind of fluorescent probe whose matrix based on rhodamine B, hydrazine hydrate and hydroxy benzaldehyde. Through the analysis of H-NMR spectra of the synthesized product L1, we confirm that the synthetic substance is the adjacent carboxyl benzaldehyde hydrazone structure generation of rhodamine B. Then, we measure the fluorescence signal intensity of the probe with different concentrations of mercury ions fully upon complexation by fluorescence spectrometer and we can study the relationship between the mercury ion concentration and the fluorescence intensity and draw the standard working curve. Following, It's time to discuss the microwave digestion processing of tea, after digestion we use the synthetic probe Li for determination of mercury content in tea. The experimental results show that the maximum excitation wavelength of the probe and coordination compound are 568. 05 and 560. 00 nm, the maximum emission wavelength are 587. 94 and 580. 00 nm. Then we can find the best testing conditions to improve the degree of accuracy, that is: room temperature, 50% the methanol solution, 3. 0 mL pH 4. 0 buffer solution, in the extent of 30 min. The experimental results show that Na+, K+, Ca2+, Cu2+, Zn2+, Al3+ have little impact on the fluorescence intensity of the:probe. Fe3+, Mg2+, Ba2+ has a weak enhancement to the fluorescence intensity of the probe. While a low concentrations of Hg2+ have an obviously enhanced effect on the fluorescence intensity of the probe. In contrast to other metal ions, the probe for Hg2+ has a good selectivity. Linear relationship between the magnitude of increase in fluorescence intensity and concentration of mercury ion was in the range of 5~20 ng . L-1 with detection limit (3S/N) of

  1. 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 82 nM and 78 nM, 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

  2. A Simple and Selective Fluorescent Sensor for Zn(2+) and H(+) Ions in Aqueous Solution with OR Logic Gate Function.

    PubMed

    Algi, Melek Pamuk

    2016-05-01

    The synthesis and properties of a new compound, viz., (N,N'-[1,10-phenanthroline-4,7-diyldi((E)methylylidene)]bis(1,10-phenanthrolin-5-amine) (1), is described. Compound 1 can be used as a selective fluorescent Zn(2+) sensor in buffered solution. Furthermore, 1 induces turn on fluorogenic response to H(+) ions. Finally, it is shown that an OR logic gate can be constructed with 1 by using Zn(2+) and H(+) as two-inputs. Graphical Abstract In this paper, the design, synthesis and physicochemical properties of a new compound 1 based on 1,10-phenanthroline scaffold, is reported. It is noted that 1 can be used as a selective fluorescent Zn(2+) sensor in 0.01 M HEPES buffer containing DMF (2 % v/v, pH = 7.4) at room temperature. Furthermore, the spectrophotometric results suggest that compound 1 can be used as a pH reporter in highly acidic conditions (pH < 5). Finally, it was also shown that an OR logic gate can be constructed with 1 by using Zn(2+) and H(+) as two-inputs. PMID:27048222

  3. Simple, Scalable, Script-Based Science Processor (S4P)

    NASA Technical Reports Server (NTRS)

    Lynnes, Christopher; Vollmer, Bruce; Berrick, Stephen; Mack, Robert; Pham, Long; Zhou, Bryan; Wharton, Stephen W. (Technical Monitor)

    2001-01-01

    The development and deployment of data processing systems to process Earth Observing System (EOS) data has proven to be costly and prone to technical and schedule risk. Integration of science algorithms into a robust operational system has been difficult. The core processing system, based on commercial tools, has demonstrated limitations at the rates needed to produce the several terabytes per day for EOS, primarily due to job management overhead. This has motivated an evolution in the EOS Data Information System toward a more distributed one incorporating Science Investigator-led Processing Systems (SIPS). As part of this evolution, the Goddard Earth Sciences Distributed Active Archive Center (GES DAAC) has developed a simplified processing system to accommodate the increased load expected with the advent of reprocessing and launch of a second satellite. This system, the Simple, Scalable, Script-based Science Processor (S42) may also serve as a resource for future SIPS. The current EOSDIS Core System was designed to be general, resulting in a large, complex mix of commercial and custom software. In contrast, many simpler systems, such as the EROS Data Center AVHRR IKM system, rely on a simple directory structure to drive processing, with directories representing different stages of production. The system passes input data to a directory, and the output data is placed in a "downstream" directory. The GES DAAC's Simple Scalable Script-based Science Processing System is based on the latter concept, but with modifications to allow varied science algorithms and improve portability. It uses a factory assembly-line paradigm: when work orders arrive at a station, an executable is run, and output work orders are sent to downstream stations. The stations are implemented as UNIX directories, while work orders are simple ASCII files. The core S4P infrastructure consists of a Perl program called stationmaster, which detects newly arrived work orders and forks a job to run the

  4. 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.

  5. Colorimetric Fluorescent Nanosensor Based on Hexamethylene Diisocyanate for Fluorescent Responses and Adsorption of Heavy Metal Ions.

    PubMed

    Xu, Yaohui; Zhou, Yang; Li, Ruixing

    2016-03-01

    An inorganic-organic hybrid material based on magnetic Fe3O4@SiO2 nanoparticles was synthesized for fluorescent responses and removal of heavy metal ions, in which superparamagnetic Fe3O4@SiO2 nanoparticles were firstly prepared and modified with hexamethylene diisocyanate (HDI) instead of 3-isocyanatopropyltriethoxysilane (IPTES) as the organic coupling agent, and then a rhodamine derivative with spirolactam structure (Rho-en) was conjugated on the HDI functionalized Fe3O4@SiO2 nanoparticles through isocyanate groups. Both of functionalized Fe3O4@SiO2 nanoparticles based on IPTES and HDI were characterized by FT-IR and XPS, and the results indicated that HDI was a good alternative as chemical bridge for surface modification on the surface of Fe3O4@SiO2 nanoparticles. The inorganic-organic hybrid composites synthesized based HDI showed naked-eye color changes and fluorescent responses towards Zn2+, Cd2+, Mn2+, Pb2+, Hg2+ and Fe3+, which could serve as the available proofs for the qualitative analysis. Moreover, the as-obtained composites not only had excellent adsorption capability for Pb2+ and Hg2+, but also showed strong magnetic sensitivity, which could help to the removal and separation of functionalized magnetic nanocomposites after capturing the heavy metal ions. In addition, the plausible interaction mode of functionalized Fe3O4@SiO2 nanoparticles with heavy metal ions was discussed. PMID:27455720

  6. Synthesis and fluorescence characteristics of ATP-based FRET probes.

    PubMed

    Hardt, Norman; Hacker, Stephan M; Marx, Andreas

    2013-12-28

    Adenosine triphosphate (ATP) analogues labelled with two dyes suitable for undergoing Förster Resonance Energy Transfer (FRET) have the potential to be valuable tools to continuously study the enzymatic activity of ATP consuming enzymes. Here, we present a synthesis strategy that allows obtaining these ATP analogues in a straight-forward manner. Earlier studies indicate that modifying ATP at the O2'- and the γ-position is a very promising starting point for the design of these probes. We synthesized probes modified with five different combinations of dyes attached to these positions and investigated their fluorescence characteristics in the non-cleaved state as well as after enzymatic hydrolysis. All presented probes largely change their fluorescence characteristics upon cleavage. They include ratiometric FRET probes as well as dark quenched analogues. For typical in vitro applications a combination of the sulfonated polymethine dyes Sulfo-Cy3 and Sulfo-Cy5 seems to be most promising due to their excellent solubility in aqueous buffer and a large change of fluorescence characteristics upon cleavage. For this combination of dyes we also synthesized analogues modified at the γ- and the C2- or the O3'-position, respectively, as these attachment sites are also well accepted by certain ATP consuming enzymes. These analogues show comparably large changes in fluorescence characteristics. Overall, we present new ATP-based FRET probes that have the potential to enable monitoring the enzymatic activity of ATP consuming enzymes. PMID:24173528

  7. Dextran-based fluorescent nanoprobes for sentinel lymph node mapping.

    PubMed

    Dai, Tingting; Zhou, Shuyan; Yin, Chuyang; Li, Shengli; Cao, Weigang; Liu, Wei; Sun, Kang; Dou, Hongjing; Cao, Yilin; Zhou, Guangdong

    2014-09-01

    Biopsy of sentinel lymph node (SLN) has become a common practice to predict whether tumor metastasis has occurred, so proper SLN positioning tracers are highly required. Due to many drawbacks of SLN tracers currently used, developing ideal, biosafe SLN imaging agents is always an urgent issue. The current study designed a novel fluorescent nanoprobe for accurate SLN mapping. Dextran-based nanogel (DNG) was prepared through a highly efficient self-assembly assisted approach and serves as a multi-functional platform for conjugating wide spectra emitting fluorescent agents. The newly fabricated fluorescent DNG (FDNG) could be designed with optimum size and stable fluorescent intensity for specific SLN imaging. Furthermore, a long-term dynamic course in vivo (from 1 min to 72 h) revealed the satisfactory specificity, sensitivity, and stability for SLN mapping. Most importantly, both in vitro and in vivo evaluations indicated that FDNG had fine biosafety and biocompatibility with lymphatic endothelial cells. All these results supported that FDNG could be used as highly efficient molecular imaging probes for specific, sensitive, stable, non-invasive, and safe SLN mapping, which provides efficient and accurate location for SLN biopsy and thus predicts tumor metastasis as well as directs therapies. Besides, our recent studies further demonstrated that DNG could also serve as a specific and controllable drug carrier, indicating a potential application for specific therapies of various lymph-associated diseases. PMID:24957293

  8. Immunosensor systems with the Langmuir-film-based fluorescence detection

    SciTech Connect

    Chudinova, G K; Nagovitsyn, I A; Savranskii, V V; Karpov, R E

    2003-09-30

    A method is developed for detecting protein antigens for fluorescent immunoassay using a model system based on the technique for preparation of Langmuir films. Fluorescein isothiocyanate and donor-acceptor energy-transfer pairs of markers (the Yb complex of tetraphenyl porphyrin - benzoyl trifluoroacetoneisothiocyanate and derivatives of tetra(carboxyphenyl) porphyrin - cyanine dye containing a five-membered polyene chain), which were nor studied earlier, were used as markers for detecting the binding of an antigen on the surface of Langmuir films of antibodies. Fluorescence was detected in the near-IR region (for the first pair) and in the visible spectral range (for the second pair). To reduce the nonspecific sorption of a protein (antigen), a method was proposed for the preparation of a nonpolar surface by applying an even number of layers of stearic acid as a substrate for the Langmuir - Blodgett film. A high sensitivity of model systems to a protein antigen in solution was achieved ({approx}10{sup -11} M), the assay time being 6 - 8 min. The model system with the first donor - acceptor pair was tested in analysis of the blood plasma. The fluorescence of the Dy{sup 3+}, Tm{sup 3+}, and Yb{sup 3+} complexes of tetraphenyl porphyrin sensitised by diketonate complexes of lanthanides was studied for the first time and the enhancement of the IR fluorescence of these complexes in a Langmuir film was demonstrated. (papers devoted to the memory of academician a m prokhorov)

  9. Label-free fluorescent molecular beacon based on a small fluorescent molecule non-covalently bound to the intentional gap site in the stem moiety.

    PubMed

    Gao, Qiang; Lin, Kai; Zhang, Hongge; Qi, Honglan; Zhang, Chengxiao

    2010-12-15

    A label-free fluorescent molecular beacon (MB) based on a fluorescent molecule, 5,6,7-trimethyl-1,8-naphthyridin-2-ylamine (ATMND) which is non-covalently bound to the intentional gap site in the stem moiety of the label-free MB, was developed. In the absence of a cDNA, ATMND fluorescence is significantly quenched because it binds to the unpaired cytosine at the gap site by hydrogen bonding. As a result, the label-free MB shows almost no fluorescence. Upon hybridization with cDNA, the label-free MB undergoes a conformational change to destroy the gap site. This results in an effective fluorescent enhancement because of the release of the ATMND from the gap site to the solution. Fluorescence titration shows that ATMND strongly binds to the cytosine at the gap site (K(11)>10(6)). Circular-dichroism spectroscopy indicates that the binding of ATMND at the gap site of the stem moiety does not induce a significant conformational change to the hairpin DNA. Under optimal conditions, the fluorescent intensity of the label-free MB increases with an increase in cDNA concentration from 50 nM to 1.5 μM. A detection limit of 20 nM cDNA was achieved. A single mismatched target ss-DNA can be effectively discriminated from cDNA. The advantage of the label-free MB is that both its ends can be left free to introduce other useful functionalities. In addition, the label-free MB synthesis introduced in this paper is relatively simple and inexpensive because no label is required. PMID:21111170

  10. Patch-based anisotropic diffusion scheme for fluorescence diffuse optical tomography—part 2: image reconstruction

    NASA Astrophysics Data System (ADS)

    Correia, Teresa; Koch, Maximilian; Ale, Angelique; Ntziachristos, Vasilis; Arridge, Simon

    2016-02-01

    Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regularisation tends to either oversmooth or generate very noisy reconstructions, depending on the regularisation strength. Edge preserving methods, such as anisotropic diffusion regularisation (AD), can preserve important features in the fluorescence image and smooth out noise. However, AD has limited ability to distinguish an edge from noise. We propose a patch-based anisotropic diffusion regularisation (PAD), where regularisation strength is determined by a weighted average according to the similarity between patches around voxels within a search window, instead of a simple local neighbourhood strategy. However, this method has higher computational complexity and, hence, we wavelet compress the patches (PAD-WT) to speed it up, while simultaneously taking advantage of the denoising properties of wavelet thresholding. Furthermore, structural information can be incorporated into the image reconstruction with PAD-WT to improve image quality and resolution. In this case, the weights used to average voxels in the image are calculated using the structural image, instead of the fluorescence image. The regularisation strength depends on both structural and fluorescence images, which guarantees that the method can preserve fluorescence information even when it is not structurally visible in the anatomical images. In part 1, we tested the method using a denoising problem. Here, we use simulated and in vivo mouse fDOT data to assess the algorithm performance. Our results show that the proposed PAD-WT method provides high quality and noise free images, superior to those obtained using AD.

  11. Simple-random-sampling-based multiclass text classification algorithm.

    PubMed

    Liu, Wuying; Wang, Lin; Yi, Mianzhu

    2014-01-01

    Multiclass text classification (MTC) is a challenging issue and the corresponding MTC algorithms can be used in many applications. The space-time overhead of the algorithms must be concerned about the era of big data. Through the investigation of the token frequency distribution in a Chinese web document collection, this paper reexamines the power law and proposes a simple-random-sampling-based MTC (SRSMTC) algorithm. Supported by a token level memory to store labeled documents, the SRSMTC algorithm uses a text retrieval approach to solve text classification problems. The experimental results on the TanCorp data set show that SRSMTC algorithm can achieve the state-of-the-art performance at greatly reduced space-time requirements. PMID:24778587

  12. A simple intensity modulation based fiber-optic accelerometer

    NASA Astrophysics Data System (ADS)

    Guozhen, Yao; Yongqian, Li; Zhi, Yang

    2016-05-01

    A fiber-optic accelerometer with simple structure and high performance based on intensity modulation is proposed. Using only a length of single mode fiber compressed by a cantilever, the intensity of reflected light is modulated by the vibration acceleration applied to it. The effects of the fiber location, the dimension parameters of the cantilever on frequency response and sensitivity are investigated. The experimental results demonstrate that the accelerometer has a flat frequency response over a 4700 Hz bandwidth and a sensitivity of 21.24 mV/g with a cantilever dimension of 30 × 8 × 1.6 mm3 and a distance of 5 mm between the fiber location and the suspended cantilever end; the coefficient of determination is better than 0.999. In addition, the effect of temperature and the stability of the sensing system are investigated.

  13. Simple-Random-Sampling-Based Multiclass Text Classification Algorithm

    PubMed Central

    Liu, Wuying; Wang, Lin; Yi, Mianzhu

    2014-01-01

    Multiclass text classification (MTC) is a challenging issue and the corresponding MTC algorithms can be used in many applications. The space-time overhead of the algorithms must be concerned about the era of big data. Through the investigation of the token frequency distribution in a Chinese web document collection, this paper reexamines the power law and proposes a simple-random-sampling-based MTC (SRSMTC) algorithm. Supported by a token level memory to store labeled documents, the SRSMTC algorithm uses a text retrieval approach to solve text classification problems. The experimental results on the TanCorp data set show that SRSMTC algorithm can achieve the state-of-the-art performance at greatly reduced space-time requirements. PMID:24778587

  14. A coumarin-indole based colorimetric and 'turn on' fluorescent probe for cyanide

    NASA Astrophysics Data System (ADS)

    Xu, Yu; Dai, Xi; Zhao, Bao-Xiang

    2015-03-01

    A novel coumarin-indole based chemodosimeter with a simple structure was designed and prepared via a condensation reaction in high yield. The probe exhibited very high selectivity towards cyanide on both fluorescence and UV-vis spectra, which allowed it to quantitatively detect and imaging cyanide ions in organic-aqueous solution by either fluorescence enhancement or colorimetric changes. Confirmed by 1H NMR and HRMS spectra, the detection mechanism was proved to be related with the Michael addition reaction induced by cyanide ions, which blocked the intramolecular charge transfer (ICT) of the probe. Moreover, the probe was able to be utilized efficiently in a wide pH range (7.5-10) with negligible interference from other anions and a low detection limit of 0.51 μM. Application in 5 kinds of natural water source and accurate detection of cyanide in tap water solvent system also indicated the high practical significance of the probe.

  15. Paper-based upconversion fluorescence resonance energy transfer biosensor for sensitive detection of multiple cancer biomarkers

    NASA Astrophysics Data System (ADS)

    Xu, Sai; Dong, Biao; Zhou, Donglei; Yin, Ze; Cui, Shaobo; Xu, Wen; Chen, Baojiu; Song, Hongwei

    2016-03-01

    A paper-based upconversion fluorescence resonance energy transfer assay device is proposed for sensitive detection of CEA. The device is fabricated on a normal filter paper with simple nano-printing method. Upconversion nanoparticles tagged with specific antibodies are printed to the test zones on the test paper, followed by the introduction of assay antigen. Upconversion fluorescence measurements are directly conducted on the test zones after the antigen-to-antibody reactions. Furthermore, a multi-channel test paper for simultaneous detection of multiple cancer biomarkers was established by the same method and obtained positive results. The device showed high anti-interfere, stability, reproducible and low detection limit (0.89 ng/mL), moreover it is very easy to fabricate and operate, which is a promising prospect for a clinical point-of-care test.

  16. Paper-based upconversion fluorescence resonance energy transfer biosensor for sensitive detection of multiple cancer biomarkers

    PubMed Central

    Xu, Sai; Dong, Biao; Zhou, Donglei; Yin, Ze; Cui, Shaobo; Xu, Wen; Chen, Baojiu; Song, Hongwei

    2016-01-01

    A paper-based upconversion fluorescence resonance energy transfer assay device is proposed for sensitive detection of CEA. The device is fabricated on a normal filter paper with simple nano-printing method. Upconversion nanoparticles tagged with specific antibodies are printed to the test zones on the test paper, followed by the introduction of assay antigen. Upconversion fluorescence measurements are directly conducted on the test zones after the antigen-to-antibody reactions. Furthermore, a multi-channel test paper for simultaneous detection of multiple cancer biomarkers was established by the same method and obtained positive results. The device showed high anti-interfere, stability, reproducible and low detection limit (0.89 ng/mL), moreover it is very easy to fabricate and operate, which is a promising prospect for a clinical point-of-care test. PMID:27001460

  17. Phenotyping transgenic embryos: a rapid 3-D screening method based on episcopic fluorescence image capturing.

    PubMed

    Weninger, Wolfgang Johann; Mohun, Timothy

    2002-01-01

    We describe a technique suitable for routine three-dimensional (3-D) analysis of mouse embryos that is based on episcopic fluorescence images captured during serial sectioning of wax-embedded specimens. We have used this procedure to describe the cardiac phenotype and associated blood vessels of trisomic 16 (Ts16) and Cited2-null mutant mice, as well as the expression pattern of an Myf5 enhancer/beta-galactosidase transgene. The consistency of the images and their precise alignment are ideally suited for 3-D analysis using video animations, virtual resectioning or commercial 3-D reconstruction software packages. Episcopic fluorescence image capturing (EFIC) provides a simple and powerful tool for analyzing embryo and organ morphology in normal and transgenic embryos. PMID:11743576

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

    SciTech Connect

    Tan, W.; Yeung, E.S. |; Parpura, V.; Haydon, P.G.

    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.

  19. Determination of adenine based on the fluorescence recovery of the L-Tryptophan-Cu2+ complex

    NASA Astrophysics Data System (ADS)

    Duan, Ruilin; Li, Chunyan; Liu, Shaopu; Liu, Zhongfang; Li, Yuanfang; Yuan, Yusheng; Hu, Xiaoli

    2016-01-01

    A simple and sensitive method for determination of adenine was developed based on fluorescence quenching and recovery of L-Tryptophan (L-Trp). The fluorescence of L-Trp could efficiently quenched by copper ion compared with other common metal ions. Upon addition of adenine (Ade) in L-Trp-Cu(II) system, the fluorescence was reoccurred. Under the optimum conditions, the recovery fluorescence intensity was linearly correlated with the concentration of adenine in the range from 0.34 to 25.0 μmol L-1, with a correlation coefficient (R2) of 0.9994. The detection limit (3σ/k) was 0.046 μmol L-1, indicating that this method could applied to detect trace adenine. In this study, amino acids including L-Trp, D-Trp, L-Tyr, D-Tyr, L-Phe, D-Phe were investigated and only L-Trp could well chelated copper ion. Additionally, the mechanism of quench and recovery also were discussed and the method was successfully applied to detect the adenine in DNA with satisfactory results.

  20. Construction of an off-on fluorescence system based on carbon dots for trace pyrophosphate sensing.

    PubMed

    Yue, Qiaoli; Hou, Yining; Yue, Shuzhen; Du, Kaimin; Shen, Tongfei; Wang, Lei; Xu, Shuling; Li, Haibo; Liu, Jifeng

    2015-05-01

    A novel and simple fluorescence Off-On system is proposed for selective pyrophosphate (PPi) sensing in an aqueous solution. The method is constructed based on the strong blue emission of carbon dots (CDs) owing to its outstanding photoluminescence and easy synthesis, which has shown exciting potential in analytical and biological field. The fluorescence of CDs can be remarkably quenched by some transition metal ions such as Cu(2+), Ni(2+), Mn(2+) and Co(2+) due to the coordination reaction between metal ions and the carboxylic groups on the surface of CDs. When PPi was introduced to CDs-metal ion system the fluorescence of CDs was recovered regularly. The increment of fluorescence intensity was proportional with the concentration of PPi in the range of 1-200 μM and correspondingly the limit of detection was calculated as 0.32 μM according to the recommendation of IUPAC as 3.29 S B/m. The possible mechanism was discussed for the detection of PPi and the quenching reaction between CDs and metal ions. Furthermore, the proposed system was successfully used to monitor the content of PPi in water samples from artificial wetland. PMID:25731813

  1. 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

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

    PubMed

    Hnyluchová, Zuzana; Bjalončíková, Petra; Karas, Pavel; Mravec, Filip; Halasová, Tereza; Pekař, Miloslav; Kubala, Lukáš; Víteček, 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 μl. 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

  3. A simple microviscometric approach based on Brownian motion tracking

    NASA Astrophysics Data System (ADS)

    Hnyluchová, Zuzana; Bjalončíková, Petra; Karas, Pavel; Mravec, Filip; Halasová, Tereza; Pekař, Miloslav; Kubala, Lukáš; Víteček, 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 μl. 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).

  4. 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

  5. A novel fluorescence-based cellular permeability assay.

    PubMed

    Chandra, Ankur; Barillas, Samuel; Suliman, Ahmed; Angle, Niren

    2007-04-10

    Vascular permeability is a pathologic process in many disease states ranging from metastatic progression of malignancies to ischemia-reperfusion injury. In order to more precisely study tissue, and more specifically cell layer permeability, our goal was to create a fluorescence-based assay which could quantify permeability without radioactivity or electrical impedance measurements. Human aortic endothelial cells were grown in monolayer culture on Costar-Transwell clear polyester membrane 6-well cell culture inserts. After monolayer integrity was confirmed, vascular endothelial growth factor (VEGF(165)) at varying concentrations with a fixed concentration of yellow-green fluorescent 0.04 microm carboxylate-modified FluoSpheres microspheres were placed in the luminal chamber and incubated for 24 h. When stimulated with VEGF(165) at 20, 40, 80, and 100 ng/ml, this assay system was able to detect increases in trans-layer flux of 8.2+/-2.4%, 16.0+/-3.7%, 41.5+/-4.9%, and 58.6+/-10.1% for each concentration, respectively. This represents the first fluorescence-based permeability assay with the sensitivity to detect changes in the permeability of a cell layer to fluid flux independent of protein flux; as well as being simpler and safer than previous radioactive-and impedance-based permeability assays. With the application of this in vitro assay to a variety of pathologic conditions, both the dynamics and physiology relating to cellular permeability can be more fully investigated. PMID:16962665

  6. A simple plasmid-based transient gene expression method using High Five cells.

    PubMed

    Shen, Xiao; Pitol, Ana K; Bachmann, Virginie; Hacker, David L; Baldi, Lucia; Wurm, Florian M

    2015-12-20

    The High Five (H5) cell line, derived from the lepidopteran Trichoplusia ni, is one of the major insect cell hosts for the production of recombinant proteins using the baculovirus expression vector system (BEVS). Here, we describe a simple polyethylenimine (PEI)-based transient gene expression (TGE) process for the rapid production of recombinant proteins from suspension-adapted H5 cells. The method was optimized using two model proteins, enhanced green fluorescent protein (EGFP) and human tumor necrosis factor receptor-Fc fusion protein (TNFR-Fc). After screening several promoter and enhancer combinations for high levels of TNFR:Fc production, an expression vector containing the Autographa californica multicapsid nucleopolyhedrovirus immediate early 1 (ie1) promoter and homologous region 5 (hr5) enhancer was selected. Cells were transfected at a density of 2×10(6) cells/mL by direct addition of DNA and PEI. Under optimized conditions, a 90% transfection efficiency (percentage of EGFP-positive cells) was obtained. In addition, we observed volumetric TNFR-Fc yields over 150μg/mL within 4 days of transfection. The method was found to be reproducible and scalable to 300mL. This plasmid-based transient transfection process is a simple and efficient alternative to the BEVS for recombinant protein production in H5 cells. PMID:26476358

  7. Simple, Defensible Sample Sizes Based on Cost Efficiency

    PubMed Central

    Bacchetti, Peter; McCulloch, Charles E.; Segal, Mark R.

    2009-01-01

    Summary The conventional approach of choosing sample size to provide 80% or greater power ignores the cost implications of different sample size choices. Costs, however, are often impossible for investigators and funders to ignore in actual practice. Here, we propose and justify a new approach for choosing sample size based on cost efficiency, the ratio of a study’s projected scientific and/or practical value to its total cost. By showing that a study’s projected value exhibits diminishing marginal returns as a function of increasing sample size for a wide variety of definitions of study value, we are able to develop two simple choices that can be defended as more cost efficient than any larger sample size. The first is to choose the sample size that minimizes the average cost per subject. The second is to choose sample size to minimize total cost divided by the square root of sample size. This latter method is theoretically more justifiable for innovative studies, but also performs reasonably well and has some justification in other cases. For example, if projected study value is assumed to be proportional to power at a specific alternative and total cost is a linear function of sample size, then this approach is guaranteed either to produce more than 90% power or to be more cost efficient than any sample size that does. These methods are easy to implement, based on reliable inputs, and well justified, so they should be regarded as acceptable alternatives to current conventional approaches. PMID:18482055

  8. A Simple, Scalable, Script-based Science Processor

    NASA Technical Reports Server (NTRS)

    Lynnes, Christopher

    2004-01-01

    The production of Earth Science data from orbiting spacecraft is an activity that takes place 24 hours a day, 7 days a week. At the Goddard Earth Sciences Distributed Active Archive Center (GES DAAC), this results in as many as 16,000 program executions each day, far too many to be run by human operators. In fact, when the Moderate Resolution Imaging Spectroradiometer (MODIS) was launched aboard the Terra spacecraft in 1999, the automated commercial system for running science processing was able to manage no more than 4,000 executions per day. Consequently, the GES DAAC developed a lightweight system based on the popular Per1 scripting language, named the Simple, Scalable, Script-based Science Processor (S4P). S4P automates science processing, allowing operators to focus on the rare problems occurring from anomalies in data or algorithms. S4P has been reused in several systems ranging from routine processing of MODIS data to data mining and is publicly available from NASA.

  9. Smartphone-based fluorescence detector for mHealth.

    PubMed

    Balsam, Joshua; Bruck, Hugh Alan; Rasooly, Avraham

    2015-01-01

    We describe here a compact smartphone-based fluorescence detector for mHealth. A key element to achieving high sensitivity using low sensitivity phone cameras is a capillary array, which increases sensitivity by 100×. The capillary array was combined with a white LED illumination system to enable wide spectra fluorescent excitation in the range of 450-740 nm. The detector utilizes an orthographic projection system to form parallel light projection images from the capillaries at a close distance via an object-space telecentric lens configuration that reduces the total lens-to-object distance while maintaining uniformity in measurement between capillaries. To further increase the limit of detection (LOD), a computational image processing approach was employed to decrease the level of noise. This enables an additional 5-10× decrease in LOD. This smartphone-based detector was used to measure serial dilutions of fluorescein with a LOD of 1 nM with image stacking and 10 nM without image stacking, similar to the LOD obtained with a commercial plate reader. Moreover, the capillary array required a sample volume of less than 10 μl, which is an order of magnitude less than the 100 μl required for the plate reader.As fluorescence detection is widely used in sensitive biomedical assays, the approach described here has the potential to increase mHealth clinical utility, especially for telemedicine and for resource-poor settings in global health applications. PMID:25626543

  10. A New Fluorescent Sensor Based on Bisindolizine Derivative.

    PubMed

    I, Anitha; M, Sheela Gopal; Thomas, Divya

    2016-03-01

    A fluorescent sensor based on 1,2,1',2'- Tetra(methoxycarbonyl)- 3,3'- bis(p-methylbenzoyl)- 7,7'-bisindolizine (MBI) showing excellent selectivity towards Fe(3+) ions was developed. Under optimized experimental conditions, the fluorescence intensity of 1,2,1',2'- Tetramethoxycarbonyl- 3,3'- bis(p-methylbenzoyl)- 7,7'-bisindolizine was quenched linearly by Fe(3+) ions in the range of 2.00 × 10(-2) to 4.76 × 10(-3) M. The limit of detection was found to be 3.17 × 10(-3) M. The mechanism for quenching was investigated. The developed sensor was applied for the determination of Fe(3+) in pharmaceutical samples. PMID:26758054

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

    PubMed Central

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

    2015-01-01

    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 yellow fluorescent protein between yeast methionine sulfoxide reductases and thioredoxins. The two sensors, named MetSOx and MetROx for their ability to detect S and R-forms of MetO, respectively, were utilized 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

  12. Hybridization assay based on evanescent fluorescence excitation and collection

    NASA Astrophysics Data System (ADS)

    Sumner, James J.; Mmerole, Robert U.; Stratis-Cullum, Dimitra N.; Yi, Hyunmin; Bentley, William E.; Gillespie, James B.

    2003-08-01

    There is a great need for high throughput and sensitive sensors for genetic analysis. These sensors can be used for varied purposes from monitoring gene expression in organims to speciation of possible pathogens. Consequently, an instrument capable of these tasks would be a great benefit for food and water safety, medical diagnostics and defense of military and civilian populations from biological threats. This work examines the development of a hybridization-based biosensor using a novel tapered fiber optic rpobe. The immobilization of single-stranded, synthetic ologinucleotides utilizing aminoproplytriethoxysilane and glutaraldehyde was implemented on the fiber optic sensor. Hybridization takes place with a complementary analyte sequence followed by a fluorescent, labeled signaling probe to form a sandwich assay. Following hybridization, the fiber is interrogated with a diode laser source and the resulting fluorescence signal is detected using a miniature spectrometer.

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

    PubMed

    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%. PMID:25485987

  14. 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%.

  15. 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.

  16. Chemical Cytometry: Fluorescence-Based Single-Cell Analysis

    NASA Astrophysics Data System (ADS)

    Cohen, Daniella; Dickerson, Jane A.; Whitmore, Colin D.; Turner, Emily H.; Palcic, Monica M.; Hindsgaul, Ole; Dovichi, Norman J.

    2008-07-01

    Cytometry deals with the analysis of the composition of single cells. Flow and image cytometry employ antibody-based stains to characterize a handful of components in single cells. Chemical cytometry, in contrast, employs a suite of powerful analytical tools to characterize a large number of components. Tools have been developed to characterize nucleic acids, proteins, and metabolites in single cells. Whereas nucleic acid analysis employs powerful polymerase chain reaction-based amplification techniques, protein and metabolite analysis tends to employ capillary electrophoresis separation and ultrasensitive laser-induced fluorescence detection. It is now possible to detect yoctomole amounts of many analytes in single cells.

  17. 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.; Schoeman, Monique A.E.; Oudshoorn, Ineke B.; Beusekom, Mara M. van; Mol, Isabel M.; Kaijzel, Eric L.; Löwik, Clemens W.G.M.; Rooij, Karien E. de

    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.

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

    PubMed Central

    Siegel, Nisan; Storrie, Brian; Bruce, Marc

    2016-01-01

    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. PMID:26839443

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

    PubMed

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

    2016-05-30

    We have designed and synthesized a simple but effective fluorescent probe for sensing glutathione (GSH) by PET process based on coumarin and quinone, which worked as fluorophore and reaction site, respectively. The probe could discriminate GSH from cysteine and homocysteine within 1 min in PBS-buffered solution. The sensing mechanism was confirmed by density functional theory (DFT), viscosity test, fluorescence spectrum analysis and HRMS, respectively. The probe has a low limit of detection (0.1 μM) and finally been used in cell imaging successfully. PMID:27154833

  20. A colorimetric and fluorescent cyanide chemosensor based on dicyanovinyl derivatives: Utilization of the mechanism of intramolecular charge transfer blocking

    NASA Astrophysics Data System (ADS)

    Li, Qiao; Cai, Yi; Yao, Hong; Lin, Qi; Zhu, Yuan-Rong; Li, Hui; Zhang, You-Ming; Wei, Tai-Bao

    2015-02-01

    Chemosensor (CS1) was designed and synthesized by simple green chemistry procedure. CS1 exhibited both colorimetric and fluorescence turn-off responses for cyanide (CN-) ion in aqueous solution. The probe showed an immediate visible color changes from yellow to colorless and green fluorescence disappearance when CN- was added. The mechanism of chemosensor reaction with CN- was studied using 1HH NMR and 13C NMR spectroscopies and mass spectrometry. Moreover, test strips based on the sensor were fabricated, which served as convenient and efficient CN- test kits.

  1. A colorimetric and fluorescent cyanide chemosensor based on dicyanovinyl derivatives: utilization of the mechanism of intramolecular charge transfer blocking.

    PubMed

    Li, Qiao; Cai, Yi; Yao, Hong; Lin, Qi; Zhu, Yuan-Rong; Li, Hui; Zhang, You-Ming; Wei, Tai-Bao

    2015-02-01

    Chemosensor (CS1) was designed and synthesized by simple green chemistry procedure. CS1 exhibited both colorimetric and fluorescence turn-off responses for cyanide (CN(-)) ion in aqueous solution. The probe showed an immediate visible color changes from yellow to colorless and green fluorescence disappearance when CN(-) was added. The mechanism of chemosensor reaction with CN(-) was studied using (1)HH NMR and (13)C NMR spectroscopies and mass spectrometry. Moreover, test strips based on the sensor were fabricated, which served as convenient and efficient CN(-) test kits. PMID:25459631

  2. A simple enzyme based biosensor on flexible plastic substrate

    NASA Astrophysics Data System (ADS)

    Kanakamedala, Senaka K.; Alshakhouri, Haidar T.; Agarwal, Mangilal; Fang, Ji; DeCoster, Mark A.

    2010-08-01

    An enzyme based biosensor was fabricated by employing a simple, inexpensive and rapid xurography fabrication process. The electrodes and channel were made from the conducting polymer poly(3,4-ethyelenedioxythiphene) poly(styrene sulfonate) (PEDOT:PSS). PEDOT:PSS was selectively deposited using a polyimide tape mask. The tape mask was peeled off from the substrate after annealing the polymer in vacuum. Polymer wells of defined dimensions were made and were attached to the device to accommodate the solutions. This sensor utilizes the change in current as a parameter to measure different analyte concentrations. Initial experiments were done by using the sensor for glucose detection. The sensor is able to detect the glucose concentrations approximately from 1 μM to 10 mM range covering glucose in human saliva (8-210 μM). The glucose oxidase activity was independently measured using colorimetric method and the results indicate that the sensor retains the enzyme activity and can be used as a biosensor to detect various analytes. The analyte of interest can be measured by preloading the corresponding enzyme into the wells.

  3. A ratiometric fluorescent probe for sensitive, selective and reversible detection of copper (II) based on riboflavin-stabilized gold nanoclusters.

    PubMed

    Zhang, Min; Le, Huynh-Nhu; Jiang, Xiao-Qin; Guo, Su-Miao; Yu, Hai-Jun; Ye, Bang-Ce

    2013-12-15

    Most of the copper (II) fluorescent probes are based on the measurement of fluorescence at a single wavelength, which may be influenced by variations in the sample environment. To the end, the ratiometric fluorescent measurement, which involves the simultaneous measurement of two fluorescence signals at different wavelengths followed by calculation of their intensity ratio, can effectively eliminate the adverse effects on fluorescence signals and give greater precision to the data analysis relative to single-channel detection. In this work, we prepared novel luminescent gold nanoclusters (AuNCs) utilizing vitamin B2 (riboflavin) as stabilizer by a simple, rapid and one-pot green (low-toxicity materials use) procedure. The as-prepared riboflavin-AuNCs (Ri-AuNCs) solution can be luminescent exhibiting two fluorescence emission peaks at 530 nm and around 840 nm with excitation at 375 nm, however, in the presence of Cu(2+), the fluorescence of the Ri-AuNCs was found to be quenched at around 840 nm and enhanced at 530 nm by Cu(2+). The resultant ratiometric fluorescent response can provide a novel sensory probe for the determination of Cu(2+). The present probe had excellent selectivity in the presence of several cations. The probe revealed a detection limit of 0.9 μM of Cu(2+). Moreover, our proposed probe can reversibly switch between the "on" and "off" states through the addition of Cu(2+) and EDTA, which is reusable in practical application. Results and method reported here provide a unique strategy for performance of ratiometric assays demonstrated with a AuNCs-based fluorescent probe, which expands the application of AuNCs. PMID:24209359

  4. Cyanine-based probe\\tag-peptide pair fluorescence protein imaging and fluorescence protein imaging methods

    DOEpatents

    Mayer-Cumblidge, M. Uljana; Cao, Haishi

    2013-01-15

    A molecular probe comprises two arsenic atoms and at least one cyanine based moiety. A method of producing a molecular probe includes providing a molecule having a first formula, treating the molecule with HgOAc, and subsequently transmetallizing with AsCl.sub.3. The As is liganded to ethanedithiol to produce a probe having a second formula. A method of labeling a peptide includes providing a peptide comprising a tag sequence and contacting the peptide with a biarsenical molecular probe. A complex is formed comprising the tag sequence and the molecular probe. A method of studying a peptide includes providing a mixture containing a peptide comprising a peptide tag sequence, adding a biarsenical probe to the mixture, and monitoring the fluorescence of the mixture.

  5. Fluorescence based Aptasensors for the determination of hepatitis B virus e antigen.

    PubMed

    Huang, Rongrong; Xi, Zhijiang; Deng, Yan; He, Nongyue

    2016-01-01

    This research is aimed at selecting specific aptamer of hepatitis B e antigen by SELEX and its applications. Hepatitis B e antigen (HBeAg) seroconversion is used as an indicator of virological response when treating patients suffering from chronic hepatitis B. HBeAg also indicates a high viremia and high infectivity in untreated patients. With HBeAg modified magnetic beads as targets, three groups of aptamers are successfully selected. These are the first reported DNA aptamers that can specifically bind to HBeAg. Based on the property that the conformation changes upon binding to its target, aptamer has emerged as ideal candidate in a variety of sensing applications. In this study, we present a simple strategy for aptamer-based fluorescence biosensors for the quantitative detection of HBeAg, in which a fluorescence labeled HBeAg aptamer serves as the molecular recognition element and a short DNA molecule that is complementary to the aptamer serves as the competitor. The LOD for HBeAg is 609 ng/mL. Later, the fluorescence system is deployed in HBeAg positive and negative blood serum (p < 0.05). The total detection assay could be completed in 2 min. These newly isolated aptamers could assist the diagnosis of chronic hepatitis B. PMID:27499342

  6. A fluorescence-based assay for human type II phospholipase A2.

    PubMed

    Blanchard, S G; Harris, C O; Parks, D J

    1994-11-01

    A fluorescence assay for quantitation of human Type II Phospholipase A2 activity is described. Hydrolysis of 1-Acyl-2-(N-4-nitrobenzo-2-oxo-1,3-diazole)aminododecanoyl Phosphatidylethanolamine is accompanied by an increase in fluorescence intensity that is linearly proportional to enzyme activity. Substrate is prepared in the absence of detergents as a sonicated dispersion in aqueous buffer. Hydrolysis of the corresponding phosphatidylcholine derivative is more than an order of magnitude slower under identical assay conditions. A plot of initial rate versus substrate concentration could be fit to a simple Michaelis-Menten relationship with Km = 13 microM. In contrast to commonly used radiochemical assays for this enzyme, the method described here is continuous and allows estimation of enzyme activity without separation of substrate from product. Thus, the method is suitable for both kinetic analysis and large-scale screening using automated readers for 96-well tissue culture plates. The fluorescence-based assay displays advantages over other continuous assays for human Type II Phospholipase A2 based on (a) high sensitivity and (b) the use of a commercially available substrate. PMID:7864369

  7. Fluorescence based Aptasensors for the determination of hepatitis B virus e antigen

    PubMed Central

    Huang, Rongrong; Xi, Zhijiang; Deng, Yan; He, Nongyue

    2016-01-01

    This research is aimed at selecting specific aptamer of hepatitis B e antigen by SELEX and its applications. Hepatitis B e antigen (HBeAg) seroconversion is used as an indicator of virological response when treating patients suffering from chronic hepatitis B. HBeAg also indicates a high viremia and high infectivity in untreated patients. With HBeAg modified magnetic beads as targets, three groups of aptamers are successfully selected. These are the first reported DNA aptamers that can specifically bind to HBeAg. Based on the property that the conformation changes upon binding to its target, aptamer has emerged as ideal candidate in a variety of sensing applications. In this study, we present a simple strategy for aptamer-based fluorescence biosensors for the quantitative detection of HBeAg, in which a fluorescence labeled HBeAg aptamer serves as the molecular recognition element and a short DNA molecule that is complementary to the aptamer serves as the competitor. The LOD for HBeAg is 609 ng/mL. Later, the fluorescence system is deployed in HBeAg positive and negative blood serum (p < 0.05). The total detection assay could be completed in 2 min. These newly isolated aptamers could assist the diagnosis of chronic hepatitis B. PMID:27499342

  8. Feasibility of a simple microsieve-based immunoassay platform.

    PubMed

    Zweitzig, Daniel R; Tibbe, Arjan G; Nguyen, Ai T; van Rijn, Cees J M; Kopnitsky, Mark J; Cichonski, Kathleen; Terstappen, Leon W M M

    2016-10-01

    The intrinsic properties of silicon microsieves, such as an optically flat surface, high overall porosity, and low flow resistance have led to an increasing number of biotechnology applications. In this report, the feasibility of creating a microsieve-based immunoassay platform was explored. Microsieves containing 5μm pores were coupled with poly-acrylic acid chains, and then mounted into a plastic holder to enable rapid reagent exchanges via a wicking mechanism. The mounted microsieves were coated with infectious disease-related antigens at [2.5 and 25μg/mL], [20 and 50μg/mL], and [20 and 100μg/mL] to facilitate detection of serum-derived human antibodies against Rubella (3-day measles), B. burgdorferi (Lyme disease), or T. pallidum (syphilis), respectively. The prototype microsieve-based immunoassay platform was able to distinguish positive control sera containing antibodies against Rubella, T. pallidum, and B. burgdorferi from negative control sera with similar qualitative results as FDA-approved ELISA tests. Testing of a WHO IgG syphilitic standard at 0.3, 0.15, 0.075, 0.0375, and 0.01875IU/mL demonstrated that the T. pallidum microsieve assay is able to distinguish disease-specific IgG signal from background signal at similar, and possibly lower, levels than the corresponding ELISA. The T. pallidum microsieve assay prototype also differentiated positive clinical serum samples from negative donor samples, and the results were in good agreement with ELISA (R(2)=0.9046). These feasibility studies demonstrate the potential for utilizing microsieves, along with a reagent wicking device, as a simple diagnostic immunoassay platform. PMID:27448458

  9. 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

  10. A VBA-based Simulation for Teaching Simple Linear Regression

    ERIC Educational Resources Information Center

    Jones, Gregory Todd; Hagtvedt, Reidar; Jones, Kari

    2004-01-01

    In spite of the name, simple linear regression presents a number of conceptual difficulties, particularly for introductory students. This article describes a simulation tool that provides a hands-on method for illuminating the relationship between parameters and sample statistics.

  11. Cell-Based Lipid Flippase Assay Employing Fluorescent Lipid Derivatives.

    PubMed

    Jensen, Maria S; Costa, Sara; Günther-Pomorski, Thomas; López-Marqués, Rosa L

    2016-01-01

    P-type ATPases in the P4 subfamily (P4-ATPases) are transmembrane proteins unique for eukaryotes that act as lipid flippases, i.e., to translocate phospholipids from the exofacial to the cytofacial monolayer of cellular membranes. While initially characterized as aminophospholipid translocases, studies of individual P4-ATPase family members from fungi, plants, and animals show that P4-ATPases differ in their substrate specificities and mediate transport of a broader range of lipid substrates. Here, we describe an assay based on fluorescent lipid derivatives to monitor and characterize lipid flippase activities in the plasma membrane of cells, using yeast as an example. PMID:26695048

  12. Homogeneous plate based antibody internalization assay using pH sensor fluorescent dye.

    PubMed

    Nath, Nidhi; Godat, Becky; Zimprich, Chad; Dwight, Stephen J; Corona, Cesear; McDougall, Mark; Urh, Marjeta

    2016-04-01

    Receptor-mediated antibody internalization is a key mechanism underlying several anti-cancer antibody therapeutics. Delivering highly toxic drugs to cancer cells, as in the case of antibody drug conjugates (ADCs), efficient removal of surface receptors from cancer cells and changing the pharmacokinetics profile of the antibody drugs are some of key ways that internalization impacts the therapeutic efficacy of the antibodies. Over the years, several techniques have been used to study antibody internalization including radiolabels, fluorescent microscopy, flow cytometry and cellular toxicity assays. While these methods allow analysis of internalization, they have limitations including a multistep process and limited throughput and are generally endpoint assays. Here, we present a new homogeneous method that enables time and concentration dependent measurements of antibody internalization. The method uses a new hydrophilic and bright pH sensor dye (pHAb dye), which is not fluorescent at neutral pH but becomes highly fluorescent at acidic pH. For receptor mediated antibody internalization studies, antibodies against receptors are conjugated with the pHAb dye and incubated with the cells expressing the receptors. Upon binding to the receptor, the dyes conjugated to the antibody are not fluorescent because of the neutral pH of the media, but upon internalization and trafficking into endosomal and lysosomal vesicles the pH drops and dyes become fluorescent. The enabling attributes of the pHAb dyes are the hydrophilic nature to minimize antibody aggregation and bright fluorescence at acidic pH which allows development of simple plate based assays using a fluorescent reader. Using two different therapeutic antibodies--Trastuzumab (anti-HER2) and Cetuximab (anti-EGFR)--we show labeling with pHAb dye using amine and thiol chemistries and impact of chemistry and dye to antibody ration on internalization. We finally present two new approaches using the pHAb dye, which will be

  13. Expression-Enhanced Fluorescent Proteins Based on Enhanced Green Fluorescent Protein for Super-resolution Microscopy.

    PubMed

    Duwé, Sam; De Zitter, Elke; Gielen, Vincent; Moeyaert, Benjamien; Vandenberg, Wim; Grotjohann, Tim; Clays, Koen; Jakobs, Stefan; Van Meervelt, Luc; Dedecker, Peter

    2015-10-27

    "Smart fluorophores", such as reversibly switchable fluorescent proteins, are crucial for advanced fluorescence imaging. However, only a limited number of such labels is available, and many display reduced biological performance compared to more classical variants. We present the development of robustly photoswitchable variants of enhanced green fluorescent protein (EGFP), named rsGreens, that display up to 30-fold higher fluorescence in E. coli colonies grown at 37 °C and more than 4-fold higher fluorescence when expressed in HEK293T cells compared to their ancestor protein rsEGFP. This enhancement is not due to an intrinsic increase in the fluorescence brightness of the probes, but rather due to enhanced expression levels that allow many more probe molecules to be functional at any given time. We developed rsGreens displaying a range of photoswitching kinetics and show how these can be used for multimodal diffraction-unlimited fluorescence imaging such as pcSOFI and RESOLFT, achieving a spatial resolution of ∼70 nm. By determining the first ever crystal structures of a negative reversibly switchable FP derived from Aequorea victoria in both the "on"- and "off"-conformation we were able to confirm the presence of a cis-trans isomerization and provide further insights into the mechanisms underlying the photochromism. Our work demonstrates that genetically encoded "smart fluorophores" can be readily optimized for biological performance and provides a practical strategy for developing maturation- and stability-enhanced photochromic fluorescent proteins. PMID:26308583

  14. BODIPY-conjugated thermoresponsive copolymer as a fluorescent thermometer based on polymer microviscosity.

    PubMed

    Wang, Dongping; Miyamoto, Ryo; Shiraishi, Yasuhiro; Hirai, Takayuki

    2009-11-17

    A simple copolymer, poly(NIPAM-co-BODIPY), consisting of N-isopropylacrylamide (NIPAM) and boradiazaindacene (BODIPY) units, behaves as a fluorescent thermometer in water. The copolymer exhibits weak fluorescence at <23 degrees C, but the intensity increases with a rise in temperature up to 35 degrees C, enabling an accurate indication of the solution temperature at 23-35 degrees C. The heat-induced fluorescence enhancement is driven by an increase in the polymer microviscosity, associated with a phase transition of the polymer from the coil to globule state. The viscous domain formed inside the globule-state polymer suppresses the rotation of the meso-pyridinium group of the excited-state BODIPY units, resulting in heat-induced fluorescence enhancement. The polymer shows reversible fluorescence enhancement/quenching regardless of the heating/cooling process and displays high reusability with a simple recovery process. PMID:19821567

  15. Novel Spectrofluorimetric Method for the Determination of Perindopril Erbumine Based on Fluorescence Quenching of Rhodamine B.

    PubMed

    Fael, Hanan; Sakur, Amir Al-Haj

    2015-11-01

    A novel, simple and specific spectrofluorimetric method was developed and validated for the determination of perindopril erbumine (PDE). The method is based on the fluorescence quenching of Rhodamine B upon adding perindopril erbumine. The quenched fluorescence was monitored at 578 nm after excitation at 500 nm. The optimization of the reaction conditions such as the solvent, reagent concentration, and reaction time were investigated. Under the optimum conditions, the fluorescence quenching was linear over a concentration range of 1.0-6.0 μg/mL. The proposed method was fully validated and successfully applied to the analysis of perindopril erbumine in pure form and tablets. Statistical comparison of the results obtained by the developed and reference methods revealed no significant differences between the methods compared in terms of accuracy and precision. The method was shown to be highly specific in the presence of indapamide, a diuretic that is commonly combined with perindopril erbumine. The mechanism of rhodamine B quenching was also discussed. PMID:26438658

  16. 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 76 nM. 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

  17. Patch-based anisotropic diffusion scheme for fluorescence diffuse optical tomography—part 1: technical principles

    NASA Astrophysics Data System (ADS)

    Correia, Teresa; Arridge, Simon

    2016-02-01

    Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regularisation tends to either oversmooth or generate very noisy reconstructions, depending on the regularisation strength. Edge preserving methods, such as anisotropic diffusion regularisation (AD), can preserve important features in the fluorescence image and smooth out noise. However, AD has limited ability to distinguish an edge from noise. In this two-part paper, we propose a patch-based anisotropic diffusion regularisation (PAD), where regularisation strength is determined by a weighted average according to the similarity between patches around voxels within a search window, instead of a simple local neighbourhood strategy. However, this method has higher computational complexity and, hence, we wavelet compress the patches (PAD-WT) to speed it up, while simultaneously taking advantage of the denoising properties of wavelet thresholding. The proposed method combines the nonlocal means (NLM), AD and wavelet shrinkage methods, which are image processing methods. Therefore, in this first paper, we used a denoising test problem to analyse the performance of the new method. Our results show that the proposed PAD-WT method provides better results than the AD or NLM methods alone. The efficacy of the method for fDOT image reconstruction problem is evaluated in part 2.

  18. Highly photoluminescent polysilsesquioxane hybrids based on weakly fluorescent 1,8-naphthalic anhydride derivatives

    NASA Astrophysics Data System (ADS)

    Pan, Fei; Huang, Miao; Song, Jianhui; Wu, Meng; Xu, Min

    2016-07-01

    A series of highly fluorescent polysilsesquioxane materials based on 1,8-naphthalic anhydride derivatives(XNA) have been prepared. The XNAs were chemically bonded with the polysiloxane. Though the fluorescent intensities of the solution of XNAs with different substitutes make a great difference, some of them are even very weakly emissive, the fluorescent intensities of the corresponding solid polysilsesquioxane materials are strong. In this case, the electronic effect of the substitute became non-important. With restricted molecular motion and J-aggregation, some traditionally weakly fluorescent or non-fluorescent chromophoric organics due to the substituent effect may be used to prepare highly fluorescent materials.

  19. Introducing a fluorescence-based standard to quantify protein partitioning into membranes.

    PubMed

    Thomas, Franziska A; Visco, Ilaria; Petrášek, Zdeněk; Heinemann, Fabian; Schwille, Petra

    2015-11-01

    The affinity of peripheral membrane proteins for a lipid bilayer can be described using the partition coefficient (KP). Although several methods to determine KP are known, all possess limitations. To address some of these issues, we developed both: a versatile method based on single molecule detection and fluorescence imaging for determining KP, and a simple measurement standard employing hexahistidine-tagged enhanced green fluorescent protein (eGFP-His6) and free standing membranes of giant unilamellar vesicles (GUVs) functionalized with NTA(Ni) lipids as binding sites. To ensure intrinsic control, our method features two measurement modes. In the single molecule mode, fluorescence correlation spectroscopy (FCS) is applied to quantify free and membrane associated protein concentrations at equilibrium and calculate KP. In the imaging mode, confocal fluorescence images of GUVs are recorded and analyzed with semi-automated software to extract protein mean concentrations used to derive KP. Both modes were compared by determining the affinity of our standard, resulting in equivalent KP values. As observed in other systems, eGFP-His6 affinity for membranes containing increasing amounts of NTA(Ni) lipids rises in a stronger-than-linear fashion. We compared our dual approach with a FCS-based assay that uses large unilamellar vesicles (LUVs), which however fails to capture the stronger-than-linear trend for our NTA(Ni)-His6 standard. Hence, we determined the KP of the MARCKS effector domain with our FCS approach on GUVs, whose results are consistent with previously published data using LUVs. We finally provide a practical manual on how to measure KP and understand it in terms of molecules per lipid surface. PMID:26342678

  20. 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 <μg/ml levels. Stability studies showed that affinity vesicles could be stored for weeks at 4°C or freeze-dried with no significant loss of binding capacity. Using an in-house fiber optic 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.

  1. Miniature fiber optic sensor based on fluorescence energy transfer

    NASA Astrophysics Data System (ADS)

    Meadows, David L.; Schultz, Jerome S.

    1992-04-01

    Optical fiber biosensors based on fluorescence assays have several distinct advantages when measuring biological analytes such as metabolites, cofactors, toxins, etc. Not only are optical signals immune to electronic interferences, but the polychromatic nature of most fluorochemical assays provides more potentially useful data about the system being studied. One of the most common difficulties normally encountered with optical biosensors is the inability to routinely recalibrate the optical and electronic components of the system throughout the life of the sensor. With this in mind, we present an optical fiber assay system for glucose based on a homogeneous singlet/singlet energy transfer assay along with the electronic instrumentation built to support the sensor system. In the sensor probe, glucose concentrations are indirectly measured from the level of fluorescence quenching caused by the homogeneous competition assay between TRITC labeled concanavalin A (receptor) and FITC labeled Dextran (ligand). The FITC signal is used to indicate glucose concentrations and the TRITC signal is used for internal calibration. Data is also presented on a protein derivatization procedure that was used to prevent aggregation of the receptor protein in solution. Also, a molecular model is described for the singlet/singlet energy transfer interactions that can occur in a model system composed of a monovalent ligand (FITC labeled papain) and a monovalent receptor (TRITC labeled concanavalin A).

  2. Development of a DMD-based fluorescence microscope

    NASA Astrophysics Data System (ADS)

    Chakrova, Nadya; Rieger, Bernd; Stallinga, Sjoerd

    2015-03-01

    We present a versatile fluorescence microscope, built by complementing a conventional fluorescence microscope with a digital micro-mirror device (DMD) in the illumination path. Arbitrary patterns can be created on the DMD and projected onto the sample. This patterned illumination can be used to improve lateral and axial resolution over the resolution of a wide-field microscope, as well as to reduce the illumination dose. Different illumination patterns require different reconstruction strategies and result in an image quality similar to confocal or structured illumination microscopy. We focus on the optical design and characterization of a DMD-based microscope. Estimation of the optical quality of the microscope has been carried out by measuring the modulation transfer function from edge profiles. We have obtained optically sectioned images by applying multi-spot illumination patterns followed by digital pinholing. The sectioning capabilities of our DMD-based microscope were estimated from the dependence of the signal-to-background and signalto-noise ratios on the pitch of the projected multi-spot patterns and the size of the digital pinhole. In addition, we provide an outlook on the use of pseudo-random illumination patterns for achieving both sectioning and resolution enhancement.

  3. Fluorescence array-based sensing of nitroaromatics using conjugated polyelectrolytes.

    PubMed

    Wu, Jiatao; Tan, Chunyan; Chen, Zhifang; Chen, Yu Zong; Tan, Ying; Jiang, Yuyang

    2016-05-23

    A sensor array consisting of six cationic fluorescent conjugated polyelectrolytes (CPEs) is reported, which could readily differentiate between nine closely related hydrophilic nitroaromatics (NACs) in separate aqueous solutions by fluorescence pattern recognition and linear discrimination analysis (LDA). PMID:27169808

  4. Physically-based in silico light sheet microscopy for visualizing fluorescent brain models

    PubMed Central

    2015-01-01

    Background We present a physically-based computational model of the light sheet fluorescence microscope (LSFM). Based on Monte Carlo ray tracing and geometric optics, our method simulates the operational aspects and image formation process of the LSFM. This simulated, in silico LSFM creates synthetic images of digital fluorescent specimens that can resemble those generated by a real LSFM, as opposed to established visualization methods producing visually-plausible images. We also propose an accurate fluorescence rendering model which takes into account the intrinsic characteristics of fluorescent dyes to simulate the light interaction with fluorescent biological specimen. Results We demonstrate first results of our visualization pipeline to a simplified brain tissue model reconstructed from the somatosensory cortex of a young rat. The modeling aspects of the LSFM units are qualitatively analysed, and the results of the fluorescence model were quantitatively validated against the fluorescence brightness equation and characteristic emission spectra of different fluorescent dyes. AMS subject classification Modelling and simulation PMID:26329404

  5. Simplified and optimized multispectral imaging for 5-ALA-based fluorescence diagnosis of malignant lesions.

    PubMed

    Minamikawa, Takeo; Matsuo, Hisataka; Kato, Yoshiyuki; Harada, Yoshinori; Otsuji, Eigo; Yanagisawa, Akio; Tanaka, Hideo; Takamatsu, Tetsuro

    2016-01-01

    5-aminolevulinic acid (5-ALA)-based fluorescence diagnosis is now clinically applied for accurate and ultrarapid diagnosis of malignant lesions such as lymph node metastasis during surgery. 5-ALA-based diagnosis evaluates fluorescence intensity of a fluorescent metabolite of 5-ALA, protoporphyrin IX (PPIX); however, the fluorescence of PPIX is often affected by autofluorescence of tissue chromophores, such as collagen and flavins. In this study, we demonstrated PPIX fluorescence estimation with autofluorescence elimination for 5-ALA-based fluorescence diagnosis of malignant lesions by simplified and optimized multispectral imaging. We computationally optimized observation wavelength regions for the estimation of PPIX fluorescence in terms of minimizing prediction error of PPIX fluorescence intensity in the presence of typical chromophores, collagen and flavins. By using the fluorescence intensities of the optimized wavelength regions, we verified quantitative detection of PPIX fluorescence by using chemical mixtures of PPIX, flavins, and collagen. Furthermore, we demonstrated detection capability by using metastatic and non-metastatic lymph nodes of colorectal cancer patients. These results suggest the potential and usefulness of the background-free estimation method of PPIX fluorescence for 5-ALA-based fluorescence diagnosis of malignant lesions, and we expect this method to be beneficial for intraoperative and rapid cancer diagnosis. PMID:27149301

  6. Simplified and optimized multispectral imaging for 5-ALA-based fluorescence diagnosis of malignant lesions

    PubMed Central

    Minamikawa, Takeo; Matsuo, Hisataka; Kato, Yoshiyuki; Harada, Yoshinori; Otsuji, Eigo; Yanagisawa, Akio; Tanaka, Hideo; Takamatsu, Tetsuro

    2016-01-01

    5-aminolevulinic acid (5-ALA)-based fluorescence diagnosis is now clinically applied for accurate and ultrarapid diagnosis of malignant lesions such as lymph node metastasis during surgery. 5-ALA-based diagnosis evaluates fluorescence intensity of a fluorescent metabolite of 5-ALA, protoporphyrin IX (PPIX); however, the fluorescence of PPIX is often affected by autofluorescence of tissue chromophores, such as collagen and flavins. In this study, we demonstrated PPIX fluorescence estimation with autofluorescence elimination for 5-ALA-based fluorescence diagnosis of malignant lesions by simplified and optimized multispectral imaging. We computationally optimized observation wavelength regions for the estimation of PPIX fluorescence in terms of minimizing prediction error of PPIX fluorescence intensity in the presence of typical chromophores, collagen and flavins. By using the fluorescence intensities of the optimized wavelength regions, we verified quantitative detection of PPIX fluorescence by using chemical mixtures of PPIX, flavins, and collagen. Furthermore, we demonstrated detection capability by using metastatic and non-metastatic lymph nodes of colorectal cancer patients. These results suggest the potential and usefulness of the background-free estimation method of PPIX fluorescence for 5-ALA-based fluorescence diagnosis of malignant lesions, and we expect this method to be beneficial for intraoperative and rapid cancer diagnosis. PMID:27149301

  7. A new turn-off fluorescence probe based on graphene quantum dots for detection of Au(III) ion

    NASA Astrophysics Data System (ADS)

    Amjadi, Mohammad; Shokri, Roghayeh; Hallaj, Tooba

    2016-01-01

    In this work, a new turn-off fluorescence probe based on the graphene quantum dots (GQDs) was designed for detection and quantification of Au(III) ion. GQDs were prepared by two simple carbonization methods using glucose (g-GQDs) and citric acid (c-GQDs) as carbon sources. The effect of some metal ions on the fluorescence intensity of the prepared GQDs was studied. It was found that the fluorescence of both GQDs is significantly quenched by Au(III) ions but the sensitivity and analytical performances are different for two prepared GQDs. Using g-GQDs, a new analytical method was developed for the determination of Au(III) in the concentration range of 1.0-80 μM, with a detection limit of 0.5 μM. The developed method was applied to the determination of Au(III) in water and plasma samples with satisfactory results.

  8. Glycol Chitosan-Based Fluorescent Theranostic Nanoagents for Cancer Therapy

    PubMed Central

    Rhee, Jin-Kyu; Park, Ok Kyu; Lee, Aeju; Yang, Dae Hyeok; Park, Kyeongsoon

    2014-01-01

    Theranostics is an integrated nanosystem that combines therapeutics with diagnostics in attempt to develop new personalized treatments with enhanced therapeutic efficacy and safety. As a promising therapeutic paradigm with cutting-edge technologies, theranostic agents are able to simultaneously deliver therapeutic drugs and diagnostic imaging agents and also monitor the response to therapy. Polymeric nanosystems have been intensively explored for biomedical applications to diagnose and treat various cancers. In recent years, glycol chitosan-based nanoagents have been developed as dual-purpose materials for simultaneous diagnosis and therapy. They have shown great potential in cancer therapies, such as chemotherapeutics and nucleic acid and photodynamic therapies. In this review, we summarize the recent progress and potential applications of glycol chitosan-based fluorescent theranostic nanoagents for cancer treatments and discuss their possible underlying mechanisms. PMID:25522316

  9. Wafer-scale aluminum plasmonics for fluorescence based biodetection

    NASA Astrophysics Data System (ADS)

    Farhang, Arash; George, Matthew C.; Williamson, Brent; Black, Mike; Wangensteen, Ted; Fraser, James; Petrova, Rumyana; Prestgard, Kent

    2015-08-01

    Moxtek has leveraged existing capabilities in wafer-scale patterning of sub-wavelength wire grid polarizers into the fabrication of 1D and 2D periodic aluminum plasmonic structures. This work will discuss progress in 200 mm diameter wafer-scale fabrication, with detailed emphasis within the realm of microarray based fluorescence detection. Aluminum nanohole arrays in a hexagonal lattice are first numerically investigated. The nanohole array geometry and periodicity are specifically tuned to coincide both with the excitation of the fluorophore Cy3, and to provide a high field enhancement within the nanoholes where labeled biomolecules are captured. This is accomplished through numerical modelling, nanofabrication, SEM imaging, and optical characterization. A 200mm diameter wafer, patterned with the optically optimized nanohole array, is cut into standard 1x3 inch microscope slide pieces and then subsequently printed with various antigens at 9 different concentrations. A sandwich bioassay is then carried out, using the corresponding conjugate antibodies in order to demonstrate specificity. The nanohole array exhibit a 3-4 times total fluorescence enhancement of Cy3, when compared to a leading commercial microarray glass slide.

  10. Direct detection of martian microorganisms based on fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Kawasaki, Y.

    1999-01-01

    The direct detection of microorganisms and their traces using optical microscopes is one of the most promising techniques to obtain the decisive evidences for extraterrestrial life. The most significant points of this technique are high sensitivity and spatial information with a resolution of 0.2mm. Besides, information on local environments and microscopic ecology can also be obtained. Many difficulties, however, must be solved to get reliable results. We have started to develop a noble technique based on the fluorescence microscopy with special interest to the detection of microorganisms in extreme environments including Mars. The principle is to detect molecules/subcellular organs which are responsible for the three basic characteristics of life; genetic information, metabolism, and discrimination of self from non-self. We have screened fluorescence probes and found several are applicable. We could detect almost all the microorganisms already identified. Discrimination of viable from dead cells was possible. The terrestrial microfossils, some of the artificial primitive microorganism-like-objects, dried bacteria and polycyclic aromatic hydrocarbons mixed with simulated Martian sand could be detected. We are now designing a compact detection hardware.

  11. MIDP-based Realization of a Simple Phone Contact Book

    NASA Astrophysics Data System (ADS)

    Niu, Yan; Xia, Heng; Huan, Lele

    This paper describes the architecture of J2ME and MIDP specification, use the Java language to implement a simple cell phone contact book system, to complete a contact to add, delete, modify, query functions. Different from existing phone contacts, it can run any MIDP-enabled mobile phones, avoid the question of using tool software into and out of phone contact book after user change phone.

  12. Simple, benign, aqueous-based amination of polycarbonate surfaces

    DOE PAGESBeta

    VanDelinder, Virginia; Wheeler, David R.; Small, Leo J.; Brumbach, Michael T.; Spoerke, Erik D.; Henderson, Ian; Bachand, George D.

    2015-03-18

    Here we report a simple, safe, environmentally-friendly aqueous method that uses diamines to functionalize a polycarbonate surface with amino groups. We demonstrate the ability of this facile method to serve as a foundation upon which other functionalities may be attached, including anti-fouling coatings and oriented membrane proteins. The use of water as the solvent for the functionalization ensures that solvent induced swelling does not affect the optical or mechanical properties of the polycarbonate.

  13. 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

  14. Frequency-domain flow cytometry: fluorescence-lifetime-based sensing technology for analyzing cells and chromosomes labeled with fluorescent probes

    NASA Astrophysics Data System (ADS)

    Steinkamp, John A.; Crissman, Harry A.; Lehnert, Bruce E.; Lehnert, Nancy M.; Deka, Chiranjit

    1997-05-01

    A flow cytometer has been developed that combines flow cytometry (FCM) and fluorescence lifetime spectroscopy measurement principles to provide unique capabilities for making frequency-domain, excited-state lifetime measurements on cells/chromosomes labeled with fluorescent probes, while preserving conventional FCM capabilities. Cells are analyzed as they intersect a high-frequency, intensity-modulated (sine-wave) laser excitation beam. Fluorescence signals are processed by (1) low-pass filtering to obtain conventional FCM dc-excited signals and (2) phase-sensitive detection electronics to resolve heterogeneous fluorescence based on differences in lifetimes expressed as phase-shifts and to quantify fluorescence lifetimes in real time. Processed signals are displayed as frequency distribution histograms and bivariate contour diagrams. Recent examples of biological applications include: (1) lifetime histograms recorded on autofluorescent human lung fibroblasts, murine thymus cells labeled with antibodies conjugated to fluorophores for studying fluorescence quenching as a function of antibody dilution and F/P ratio, and on cultured cells, nuclei, and chromosomes stained with DNA-binding fluorochromes and (2) phase-resolved, fluorescence signal- intensity histograms recorded on autofluorescent HLFs labeled with immunofluorescence markers and on murine thymus cells labeled with Red 613-antiThy 1.2 and propidium iodide (PI positive `dead' cells) to demonstrate the resolution of signals from highly overlapping emission spectra. This technology will increase the number of fluorescent markers usable in multilabeling studies and lifetimes can be used as spectroscopic probes to study the interaction of markers with their targets, each other, and the surrounding microenvironment.

  15. Development of fluorescence-based high-throughput screening assays: choice of appropriate instrumentation

    NASA Astrophysics Data System (ADS)

    Burns, David J.; Alder, Elisabeth; Fan, Yi-Hong; McKeegan, Evelyn; Warrior, Usha; Beutel, Bruce

    1998-04-01

    Fluorescence-based assays have become increasingly popular in high throughput screening for a variety of reasons (e.g. sensitivity). However, new screening technologies are pushing the limits of conventional fluorescence plate readers. For example, instruments that have optical sensitivities beyond most of the commercially available plate readers are required to reproducibly measure the fluorescence generated by the green fluorescent protein (GFP)--a novel reporter gene. Also, miniaturization of screening formats (with densities higher than the conventional 96-well plate) requires high resolution instrumentation to measure fluorescence. Several assays based on optical fluorescence measurements have been developed and screened in our Biological Screening group. These assays include various fluorescence-based protease assays (standard end-point and kinetic modes) and a functional cell-based screen using the green fluorescent protein as a reporter gene. The choice of instrumentation was the critical factor in the performance and success of each of these arrays. Data will be presented for the cell- based reporter assay including the type of instrumentation (fluorescence plate readers; fluorescence imaging systems) used for detection of GFP fluorescence.

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

    PubMed

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

    2015-07-01

    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

  17. A simple and sensitive fluorescence method for the determination of trace ozone in air using acridine red as a probe.

    PubMed

    Liu, Qingye; Lin, Chenyin; Zhang, Xinghui; Wen, Guiqing; Liang, Aihui

    2014-12-01

    The ozone in an air sample was trapped by H3 BO3 -LK solution to produce iodine (I2) that interacted with excess I(-) to form I3(-). In pH 4.0 acetate buffer solutions, the I3(-) reacted with acridine red to form acridine red-I3 ion association particles that resulted in the fluorescence peak decreased at 553 nm. The decreased value ΔF553 nm is linear to the O3 concentration in the range 0.08-53.3 × 10(-6) mol/L, with a detection limit of 4 × 10(-8) mol/L. This fluorescence method was used to determine ozone in air samples, and the results were in agreement with that of indigo carmine spectrophotometry. PMID:24733669

  18. 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

  19. 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

  20. A simple highly efficient non invasive EMG-based HMI.

    PubMed

    Vitiello, N; Olcese, U; Oddo, C M; Carpaneto, J; Micera, S; Carrozza, M C; Dario, P

    2006-01-01

    Muscle activity recorded non-invasively is sufficient to control a mobile robot if it is used in combination with an algorithm for its asynchronous analysis. In this paper, we show that several subjects successfully can control the movements of a robot in a structured environment made up of six rooms by contracting two different muscles using a simple algorithm. After a small training period, subjects were able to control the robot with performances comparable to those achieved manually controlling the robot. PMID:17945773

  1. A naphthalimide-based fluorescent sensor for halogenated solvents.

    PubMed

    Dai, Li; Wu, Di; Qiao, Qinglong; Yin, Wenting; Yin, Jun; Xu, Zhaochao

    2016-02-01

    A fluorescent sensor for halogenated solvents termed AMN is reported. AMN shows strong fluorescence in most halogenated solvents (QE > 0.1) but weak fluorescence (QE<0.01) in most non-halogenated solvents. In chlorinated solvents, the fluorescence intensity decreased with the reduction of chlorine content. On the contrary, in brominated solvents the fluorescence intensity increased with the reduction of bromine content. It is worth mentioning that AMN displayed fluorescence emission centered at 520 nm in CCl4 with a quantum yield of 0.607, at 556 nm in CHCl3 with a quantum yield of 0.318, at 584 nm in CH2Cl2 with a quantum yield of 0.128, whereas in CHBr3 was centered at 441 nm with a quantum yield of 0.012. AMN was shown to have the ability to differentiate CCl4, CHCl3, CH2Cl2 and CHBr3 halogenated solvents. PMID:26691881

  2. Fluorogen-based reporters for fluorescence imaging: a review

    NASA Astrophysics Data System (ADS)

    Jullien, Ludovic; Gautier, Arnaud

    2015-12-01

    Fluorescence bioimaging has recently jumped into a new area of spatiotemporal resolution and sensitivity thanks to synergistic advances in both optical physics and probe/biosensor design. This review focuses on the recent development of genetically encodable fluorescent reporters that bind endogenously present or exogenously applied fluorogenic chromophores (so-called fluorogens) and activate their fluorescence. We highlight the innovative engineering and design that gave rise to these new natural and synthetic fluorescent reporters, and describe some of the emerging applications in imaging and biosensing.

  3. 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.

  4. Direct Georeferencing of Uav Data Based on Simple Building Structures

    NASA Astrophysics Data System (ADS)

    Tampubolon, W.; Reinhardt, W.

    2016-06-01

    Unmanned Aerial Vehicle (UAV) data acquisition is more flexible compared with the more complex traditional airborne data acquisition. This advantage puts UAV platforms in a position as an alternative acquisition method in many applications including Large Scale Topographical Mapping (LSTM). LSTM, i.e. larger or equal than 1:10.000 map scale, is one of a number of prominent priority tasks to be solved in an accelerated way especially in third world developing countries such as Indonesia. As one component of fundamental geospatial data sets, large scale topographical maps are mandatory in order to enable detailed spatial planning. However, the accuracy of the products derived from the UAV data are normally not sufficient for LSTM as it needs robust georeferencing, which requires additional costly efforts such as the incorporation of sophisticated GPS Inertial Navigation System (INS) or Inertial Measurement Unit (IMU) on the platform and/or Ground Control Point (GCP) data on the ground. To reduce the costs and the weight on the UAV alternative solutions have to be found. This paper outlines a direct georeferencing method of UAV data by providing image orientation parameters derived from simple building structures and presents results of an investigation on the achievable results in a LSTM application. In this case, the image orientation determination has been performed through sequential images without any input from INS/IMU equipment. The simple building structures play a significant role in such a way that geometrical characteristics have been considered. Some instances are the orthogonality of the building's wall/rooftop and the local knowledge of the building orientation in the field. In addition, we want to include the Structure from Motion (SfM) approach in order to reduce the number of required GCPs especially for the absolute orientation purpose. The SfM technique applied to the UAV data and simple building structures additionally presents an effective tool

  5. 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.

  6. 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.

  7. Upconversion Nanoparticles and Monodispersed Magnetic Polystyrene Microsphere Based Fluorescence Immunoassay for the Detection of Sulfaquinoxaline in Animal-Derived Foods.

    PubMed

    Hu, Gaoshuang; Sheng, Wei; Zhang, Yan; Wang, Junping; Wu, Xuening; Wang, Shuo

    2016-05-18

    A novel fluorescence immunoassay for detecting sulfaquinoxaline (SQX) in animal-derived foods was developed using NaYF4:Yb/Tm upconversion nanoparticles (UCNPs) conjugated with antibodies as fluorescence signal probes, and monodisperse magnetic polystyrene microspheres (MMPMs) modified with coating antigen as immune-sensing capture probes for trapping and separating the signal probes. Based on a competitive immunoassay format, the detection limit of the proposed method for detecting SQX was 0.1 μg L(-1) in buffer and 0.5 μg kg(-1) in food samples. The recoveries of SQX in spiked samples ranged from 69.80 to 133.00%, with coefficients of variation of 0.24-25.06%. The extraction procedure was fast, simple, and environmentally friendly, requiring no organic solvents. In particular, milk samples can be analyzed directly after simple dilution. This method has appealing properties, such as sensitive fluorescence response, a simple and fast extraction procedure, and environmental friendliness, and could be applied to detecting SQX in animal-derived foods. PMID:27134048

  8. Rapid and quantitative detection of 4(5)-methylimidazole in caramel colours: A novel fluorescent-based immunochromatographic assay.

    PubMed

    Wu, Xinlan; Huang, Minghui; Yu, Shujuan; Kong, Fansheng

    2016-01-01

    A novel fluorescence-based immunochromatographic assay (ICA) for rapid detecting 4(5)-methylimidazole (4-MI) is presented in this study. In our work, the conjugates of fluorescent microspheres (FMs) and 4-MI monoclonal antibody were used as probe for ICA. Under optimal conditions, a standard curve of ICA-based detection of 4-MI was developed, linear detection ranged from 0.50 to 32.0 mg/L. The cross-reactivities were observed less than 3.93% by detecting 6 selected structural analogues of 4-MI. The recoveries of 4-MI in caramels detection were ranged from 82.85% to 102.31%, with the coefficient of variation (n = 3) below 9.06%. Quantitative comparison of the established fluorescence-based ICA with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) analysis of real caramel colour samples indicated a good correlation among the methods. Therefore, our developed fluorescence-based ICA method shows great potential for simple, rapid, sensitive, and cost-effective quantitative detection of 4-MI in food safety control. PMID:26213047

  9. Fluorescent glutathione probe based on MnO2-phenol formaldehyde resin nanocomposite.

    PubMed

    Wang, Xudong; Wang, Dan; Guo, Yali; Yang, Chengduan; Liu, Xiaoyu; Iqbal, Anam; Liu, Weisheng; Qin, Wenwu; Yan, Dan; Guo, Huichen

    2016-03-15

    MnO2-phenol formaldehyde resin (MnO2-PFR) nanocomposite is successfully prepared by a simple chemical reduction process. The resultant MnO2-PFR nanocomposite is well characterized. The absorption band of non-fluorescent MnO2 nanosheets overlaps well with the fluorescence emission of PFR nanoparticles. The green fluorescence of PFR in this nanocomposite can be effectively quenched by fluorescence resonance energy transfer from PFR to MnO2. In the presence of glutathione (GSH), the fluorescence of PFR could be recovered due to MnO2 was reduced to Mn(2+) by GSH. The nanocomposite can be use for detecting glutathione in blood serum. PMID:26426853

  10. Carbon dots-based fluorescent probe for "off-on" sensing of Hg(II) and I⁻.

    PubMed

    He, Jiangling; Zhang, Haoran; Zou, Jinliang; Liu, Yingliang; Zhuang, Jianle; Xiao, Yong; Lei, Bingfu

    2016-05-15

    Herein, we report a simple, one-step reflux method for synthesis of photoluminescent carbon dots (CDs) using citric acid as the carbon source and diethylenetriamine (DETA) as the surface passivation reagent along with a high quantum yield (82.40%), the fluorescence intensity of the CDs was found to be effectively quenched by Hg(II) ions. Upon addition of I(-) to the CDs/Hg(II) complex dispersion, the fluorescence intensity of the CDs was significantly recovered. Furthermore, we developed an "off-on" fluorescence assay for the detection of I(-) using CDs/Hg(II) as a fluorescence probe. This probe enables the selective detection of Hg(II) with a linear range of 0-80 μM and a limit of detection is 0.201 µM and a limit of detection about I(-) is 0.234 µM with a linear range of 0-70 μM. Most importantly, the sensors can be successfully applied to the determination of Hg(II) and I(-) in real lake water and urine of cattles, the "off-on" sensor demonstrates high selectivity, repeatability, stability, which offer this CDs-based "off-on" fluorescent sensor a promising platform for environmental and biological sensing applications. PMID:26748370

  11. A simple chip free-flow electrophoresis for monosaccharide sensing via supermolecule interaction of boronic acid functionalized quencher and fluorescent dye.

    PubMed

    Yin, Xiao-Yang; Dong, Jing-Yu; Wang, Hou-Yu; Li, Si; Fan, Liu-Yin; Cao, Cheng-Xi

    2013-08-01

    Here, a simple micro free-flow electrophoresis (μFFE) was developed for fluorescence sensing of monosaccharide via supermolecule interaction of synthesized boronic acid functionalized benzyl viologen (ο-BBV) and fluorescent dye. The μFFE contained two open electrode cavities and an ion-exchange membrane was sandwiched between two polymethylmethacrylate plates. The experiments demonstrated the following merits of developed μFFE: (i) up to 90.5% of voltage efficiency due to high conductivity of ion-exchange membrane; (ii) a strong ability against influence of bubble produced in two electrodes due to open design of electrode cavities; and (iii) reusable and washable separation chamber (45 mm × 17 mm × 100 μm, 77 μL) avoiding the discard of μFFE due to blockage of solute precipitation in chamber. Remarkably, the μFFE was first designed for the sensing of monosaccharide via the supermolecule interaction of synthesized ο-BBV, fluorescent dye, and monosaccharide. Under the optimized conditions, the minimum concentration of monosaccharide that could be detected was 1 × 10(-11) M. Finally, the developed device was used for the detection of 0.3 mM glucose spiked in human urine. All of the results demonstrated the feasibility of monosaccharide detection via the μFFE. PMID:23712879

  12. Unusual non-fluorescent broad spectrum siderophore activity (SID EGYII) by Pseudomonas aeruginosa strain EGYII DSM 101801 and a new insight towards simple siderophore bioassay.

    PubMed

    Embaby, Amira M; Heshmat, Yasmin; Hussein, Ahmed

    2016-03-01

    Present study highlights an unusual non-fluorescent hydroxamate broad spectrum siderophore (SID EGYII) activity from Pseudomonas aeruginosa strain EGYII DSM 101801, a soil bacterial isolate, along with simple low cost effective siderophore bioassay. Detection of SID EGYII activity qualitatively was proved by masking this activity against Erwinia amylovora strain EGY1 DSM 101800, an indicator strain, in well-cut diffusion assay containing 100 µM FeCl3. SID EGYII activity was expressed quantitatively as arbitrary units [Siderophore arbitrary units (SAU)] 380 SAU/mL against E. amylovora strain EGY1 DSM 101800. Maximal SID EGYII activity was achieved upon growing P. aeruginosa strain EGYII DSM 101801 in PYB broth at 180 rpm for 24 h. SID EGYII displayed a broad spectrum antimicrobial activity against some human pathogens (i.e., Gram-positive bacteria, Gram-negative bacteria and yeasts) and a fireblight plant pathogen. Interestingly, transformants of Escherichia coli JM109 (DE3)pSID/EGYII harboring P. aeruginosa strain EGYII DSM 101801 plasmid demonstrated a perceivable antimicrobial activity against E. amylovora strain EGY1 DSM 101800. The broad spectrum antimicrobial activity of the unusual non-fluorescent SID EGYII would underpin its high potential in targeting bacterial pathogens posing probable threats to human health and agricultural economy. The present simple low cost effective bioassay is a new insight towards an alternative to the expensive cumbersome siderophore Chrome Azurol S assay. PMID:27015845

  13. A simple one-step method to prepare fluorescent carbon dots and their potential application in non-invasive glioma imaging

    NASA Astrophysics Data System (ADS)

    Ruan, Shaobo; Qian, Jun; Shen, Shun; Zhu, Jianhua; Jiang, Xinguo; He, Qin; Gao, Huile

    2014-08-01

    Fluorescent carbon dots (CD) possess impressive potential in bioimaging because of their low photobleaching, absence of optical blinking and good biocompatibility. However, their relatively short excitation/emission wavelengths restrict their application in in vivo imaging. In the present study, a kind of CD was prepared by a simple heat treatment method using glycine as the only precursor. The diameter of CD was lower than 5 nm, and the highest emission wavelength was 500 nm. However, at 600 nm, there was still a relatively strong fluorescent emission, suggesting CD could be used for in vivo imaging. Additionally, several experiments demonstrated that CD possessed good serum stability and low cytotoxicity. In vitro, CD could be taken up into C6 glioma cells in a time- and concentration-dependent manner, with both endosomes and mitochondria involved. In vivo, CD could be used for non-invasive glioma imaging because of its high accumulation in the glioma site of the brain, which was demonstrated by both in vivo imaging and ex vivo tissue imaging. Furthermore, the fluorescent distribution in tissue slices also showed CD distributed in glioma with high intensity, while with a low intensity in normal brain tissue. In conclusion, CD were prepared using a simple method with relatively long excitation and emission wavelengths and could be used for non-invasive glioma imaging.Fluorescent carbon dots (CD) possess impressive potential in bioimaging because of their low photobleaching, absence of optical blinking and good biocompatibility. However, their relatively short excitation/emission wavelengths restrict their application in in vivo imaging. In the present study, a kind of CD was prepared by a simple heat treatment method using glycine as the only precursor. The diameter of CD was lower than 5 nm, and the highest emission wavelength was 500 nm. However, at 600 nm, there was still a relatively strong fluorescent emission, suggesting CD could be used for in vivo imaging

  14. 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

  15. 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

  16. Latest methods of fluorescence-based protein crystal identification

    SciTech Connect

    Meyer, Arne; Betzel, Christian

    2015-01-28

    Fluorescence, whether intrinsic or by using trace fluorescent labeling, can be a powerful aid in macromolecule crystallization. Its use in screening for crystals is discussed here. 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.

  17. Synthesis of fluorescent probes based on the pyochelin siderophore scaffold.

    PubMed

    Noël, Sabrina; Guillon, Laurent; Schalk, Isabelle J; Mislin, Gaëtan L A

    2011-03-01

    Pyochelin is a siderophore common to several pathogenic bacterial strains. Two conjugates, 1 and 2, between the NBD (4-nitro-benzo[1,2,5]oxadiazole) fluorophore and an N3''-functionalized pyochelin were synthesized. These fluorescent probes unexpectedly increased their fluorescence in an aqueous medium in the presence of iron(III) and were transported into bacterial cells. PMID:21294578

  18. A Simple and Sensitive Method for Auramine O Detection Based on the Binding Interaction with Bovin Serum Albumin.

    PubMed

    Yan, Jingjing; Huang, Xin; Liu, Shaopu; Yang, Jidong; Yuan, Yusheng; Duan, Ruilin; Zhang, Hui; Hu, Xiaoli

    2016-01-01

    A simple, rapid and effective method for auramine O (AO) detection was proposed by fluorescence and UV-Vis absorption spectroscopy. In the BR buffer system (pH 7.0), AO had a strong quenching ability to the fluorescence of bovin serum albumin (BSA) by dynamic quenching. In terms of the thermodynamic parameters calculated as ΔH > 0 and ΔS > 0, the resulting binding of BSA and AO was mainly attributed to the hydrophobic interaction forces. The linearity of this method was in the concentration range from 0.16 to 50 μmol L(-1) with a detection limit of 0.05 μmol L(-1). Based on fluorescence resonance energy transfer (FRET), the distance r (1.36 nm) between donor (BSA) and acceptor (AO) was obtained. Furthermore, the effects of foreign substances and ionic strength were evaluated under the optimum reaction conditions. BSA as a selective probe could be applied to the analysis of AO in medicines with satisfactory results. PMID:27506706

  19. Novel Chalcone-Based Fluorescent Human Histamine H3 Receptor Ligands as Pharmacological Tools

    PubMed Central

    Tomasch, Miriam; Schwed, J. Stephan; Weizel, Lilia; Stark, Holger

    2012-01-01

    Novel fluorescent chalcone-based ligands at human histamine H3 receptors (hH3R) have been designed, synthesized, and characterized. Compounds described are non-imidazole analogs of ciproxifan with a tetralone motif. Tetralones as chemical precursors and related fluorescent chalcones exhibit affinities at hH3R in the same concentration range like the reference antagonist ciproxifan (hH3R pKi value of 7.2). Fluorescence characterization of our novel ligands shows emission maxima about 570 nm for yellow fluorescent chalcones and ≥600 nm for the red fluorescent derivatives. Interferences to cellular autofluorescence could be excluded. All synthesized chalcone compounds could be used to visualize hH3R proteins in stably transfected HEK-293 cells using confocal laser scanning fluorescence microscopy. These novel fluorescent ligands possess high potential to be used as pharmacological tools for hH3R visualization in different tissues. PMID:22470321

  20. Rapid, simple and inexpensive production of custom 3D printed equipment for large-volume fluorescence microscopy

    PubMed Central

    Tyson, Adam L.; Hilton, Stephen T.; Andreae, Laura C.

    2015-01-01

    The cost of 3D printing has reduced dramatically over the last few years and is now within reach of many scientific laboratories. This work presents an example of how 3D printing can be applied to the development of custom laboratory equipment that is specifically adapted for use with the novel brain tissue clearing technique, CLARITY. A simple, freely available online software tool was used, along with consumer-grade equipment, to produce a brain slicing chamber and a combined antibody staining and imaging chamber. Using standard 3D printers we were able to produce research-grade parts in an iterative manner at a fraction of the cost of commercial equipment. 3D printing provides a reproducible, flexible, simple and cost-effective method for researchers to produce the equipment needed to quickly adopt new methods. PMID:25797056

  1. Rapid, simple and inexpensive production of custom 3D printed equipment for large-volume fluorescence microscopy.

    PubMed

    Tyson, Adam L; Hilton, Stephen T; Andreae, Laura C

    2015-10-30

    The cost of 3D printing has reduced dramatically over the last few years and is now within reach of many scientific laboratories. This work presents an example of how 3D printing can be applied to the development of custom laboratory equipment that is specifically adapted for use with the novel brain tissue clearing technique, CLARITY. A simple, freely available online software tool was used, along with consumer-grade equipment, to produce a brain slicing chamber and a combined antibody staining and imaging chamber. Using standard 3D printers we were able to produce research-grade parts in an iterative manner at a fraction of the cost of commercial equipment. 3D printing provides a reproducible, flexible, simple and cost-effective method for researchers to produce the equipment needed to quickly adopt new methods. PMID:25797056

  2. Fluorescence-Based Assessment of Plasma-Induced Hydrophilicity in Microfluidic Devices via Nile Red Adsorption and Depletion

    PubMed Central

    2015-01-01

    We present a simple method, called fluorescence-based assessment of plasma-induced hydrophilicity (FAPH), that enables spatial mapping of the local hydrophilicity of surfaces normally inaccessible by traditional contact angle measurement techniques. The method leverages the change in fluorescence of a dye, Nile Red, which is adsorbed on an oxygen plasma-treated surface, and its correlation with the contact angle of water. Using FAPH, we explored the effect of microchannel geometries on the penetration distance of oxygen plasma into a microchannel and found that entrance effects prevent uniform treatment. We showed that these variations have a significant impact on cell culture, and thus the design of cell-based microfluidic assays must consider this phenomenon to obtain repeatable and homogeneous results. PMID:25032783

  3. Label-free fluorescence turn-on detection of uracil DNA glycosylase activity based on G-quadruplex formation.

    PubMed

    Ma, Changbei; Wu, Kefeng; Liu, Haisheng; Xia, Kun; Wang, Kemin; Wang, Jun

    2016-11-01

    We have developed a new methodology for fluorescence turn-on detection of uracil DNA glycosylase (UDG) activity based on G-quadruplex formation using a thioflavin T probe. In the presence of UDG, it catalyzed the hydrolysis of the uracil bases in the duplex DNA, resulting in the dissociation of the duplex DNA owing to their low melting temperature. Then, the probe DNA can be recognized quickly by the ThT dye and resulting in an increase in fluorescence. This approach is highly selective and sensitive with a detection limit of 0.01U/mL. It is simple and cost effective without requirement of labeling with a fluorophore-quencher pair. This new method could be used to evaluate the inhibition effect of 5-fluorouracil on UDG activity, and become a useful tool in biomedical research. PMID:27591637

  4. Fluorescent zinc and copper complexes for detection of adrafinil in paper-based microfluidic devices.

    PubMed

    Caglayan, Mehmet Gokhan; Sheykhi, Sara; Mosca, Lorenzo; Anzenbacher, Pavel

    2016-07-01

    Recognition of electroneutral Lewis bases and anions in aqueous media is extremely difficult. We show that fluorescent coordinatively unsaturated metal complexes can recognize various Lewis bases while providing an easy-to-detect fluorescence response. This approach is applied to the detection of adrafinil, a banned performance-enhancing drug. PMID:27293080

  5. 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.

  6. Complexation induced fluorescence and acid-base properties of dapoxyl dye with γ-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 γ-cyclodextrin (γ-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 γ-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 γ-CD. PMID:26028009

  7. Simple hobby computer-based off-gas analysis system

    SciTech Connect

    Forrest, E.H.; Jansen, N.B.; Flickinger, M.C.; Tsao, G.T.

    1981-02-01

    An Apple II computer has been adapted to monitor fermentation offgas in laboratory and pilot scale fermentors. It can calculate oxygen uptake rates, carbon dioxide evolution rates, respiratory quotient as well as initiating recalibration procedures. In this report the computer-based off-gas analysis system is described.

  8. Indocyanine green-based fluorescent angiography in breast reconstruction

    PubMed Central

    Chae, Michael P.; Rozen, Warren Matthew

    2016-01-01

    Background Fluorescent angiography (FA) has been useful for assessing blood flow and assessing tissue perfusion in ophthalmology and other surgical disciplines for decades. In plastic surgery, indocyanine green (ICG) dye-based FA is a relatively novel imaging technology with high potential in various applications. We review the various FA detector systems currently available and critically appraise its utility in breast reconstruction. Methods A review of the published English literature dating from 1950 to 2015 using databases, such as PubMed, Medline, Web of Science, and EMBASE was undertaken. Results In comparison to the old fluorescein dye, ICG has a superior side effect profile and can be accurately detected by various commercial devices, such as SPY Elite (Novadaq, Canada), FLARE (Curadel LLC, USA), PDE-Neo (Hamamatsu Photonics, Japan), Fluobeam 800 (Fluoptics, France), and IC-View (Pulsion Medical Systems AG, Germany). In breast reconstruction, ICG has established as a safer, more accurate tracer agent, in lieu of the traditional blue dyes, for detection of sentinel lymph nodes with radioactive isotopes (99m-Technetium). In prosthesis-based breast reconstruction, intraoperative assessment of the mastectomy skin flap to guide excision of hypoperfused areas translates to improved clinical outcomes. Similarly, in autologous breast reconstructions, FA can be utilized to detect poorly perfused areas of the free flap, evaluate microvascular anastomosis for patency, and assess SIEA vascular territory for use as an alternative free flap with minimal donor site morbidity. Conclusions ICG-based FA is a novel, useful tool for various applications in breast reconstruction. More studies with higher level of evidence are currently lacking to validate this technology. PMID:27047782

  9. Development of a quantitative fluorescence-based ligand-binding assay

    PubMed Central

    Breen, Conor J.; Raverdeau, Mathilde; Voorheis, H. Paul

    2016-01-01

    A major goal of biology is to develop a quantitative ligand-binding assay that does not involve the use of radioactivity. Existing fluorescence-based assays have a serious drawback due to fluorescence quenching that accompanies the binding of fluorescently-labeled ligands to their receptors. This limitation of existing fluorescence-based assays prevents the number of cellular receptors under investigation from being accurately measured. We have developed a method where FITC-labeled proteins bound to a cell surface are proteolyzed extensively to eliminate fluorescence quenching and then the fluorescence of the resulting sample is compared to that of a known concentration of the proteolyzed FITC-protein employed. This step enables the number of cellular receptors to be measured quantitatively. We expect that this method will provide researchers with a viable alternative to the use of radioactivity in ligand binding assays. PMID:27161290

  10. Development of a quantitative fluorescence-based ligand-binding assay.

    PubMed

    Breen, Conor J; Raverdeau, Mathilde; Voorheis, H Paul

    2016-01-01

    A major goal of biology is to develop a quantitative ligand-binding assay that does not involve the use of radioactivity. Existing fluorescence-based assays have a serious drawback due to fluorescence quenching that accompanies the binding of fluorescently-labeled ligands to their receptors. This limitation of existing fluorescence-based assays prevents the number of cellular receptors under investigation from being accurately measured. We have developed a method where FITC-labeled proteins bound to a cell surface are proteolyzed extensively to eliminate fluorescence quenching and then the fluorescence of the resulting sample is compared to that of a known concentration of the proteolyzed FITC-protein employed. This step enables the number of cellular receptors to be measured quantitatively. We expect that this method will provide researchers with a viable alternative to the use of radioactivity in ligand binding assays. PMID:27161290