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Sample records for generation-atomic fluorescence detection

  1. Electrochemical hydride generation atomic fluorescence spectrometry for detection of tin in canned foods using polyaniline-modified lead cathode

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Xianjuan [Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Gan Wuer, E-mail: wgan@ustc.edu.cn [Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wan Lingzhong; Deng Yun; Yang Qinghua; He Youzhao [Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2010-12-15

    An electrochemical hydride generation system with polyaniline-modified lead cathode was developed for tin determination by coupling with atomic fluorescence spectrometry. The tin fluorescence signal intensity was improved evidently as the polyaniline membrane could facilitate the transformation process from atomic tin to the SnH{sub 4} and prevent the aggradation of Sn atom on Pb electrode surface. The effects of experimental parameters and interferences have been studied. The limit of detection (LOD) was 1.5 ng mL{sup -1} (3{sigma}) and the relative standard deviation (RSD) was 3.3% for 11 consecutive measurements of 50 ng mL{sup -1} Sn(IV) standard solution.

  2. Electrochemical hydride generation atomic fluorescence spectrometry for detection of tin in canned foods using polyaniline-modified lead cathode.

    Science.gov (United States)

    Jiang, Xianjuan; Gan, Wuer; Wan, Lingzhong; Deng, Yun; Yang, Qinghua; He, Youzhao

    2010-12-15

    An electrochemical hydride generation system with polyaniline-modified lead cathode was developed for tin determination by coupling with atomic fluorescence spectrometry. The tin fluorescence signal intensity was improved evidently as the polyaniline membrane could facilitate the transformation process from atomic tin to the SnH(4) and prevent the aggradation of Sn atom on Pb electrode surface. The effects of experimental parameters and interferences have been studied. The limit of detection (LOD) was 1.5 ng mL(-1) (3σ) and the relative standard deviation (RSD) was 3.3% for 11 consecutive measurements of 50 ng mL(-1) Sn(IV) standard solution. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Multipumping flow system for improving hydride generation atomic fluorescence spectrometric determinations

    International Nuclear Information System (INIS)

    Lopez-Garcia, Ignacio; Ruiz-Alcaraz, Irene; Hernandez-Cordoba, Manuel

    2006-01-01

    The advantages of using membrane micropumps rather than peristaltic pumps to introduce both sample and reagent solutions for hydride generation atomic fluorescence spectrometry are discussed. Arsenic was used as a test analyte to check the performance of the proposed manifold. Sample and reagent consumption was reduced 8-9 fold compared with continuous mode measurements made with peristaltic pumps, with no deterioration in sensitivity. The calibration graph was linear in the 0.05 to 2.5 μg l -1 As range using peak area as the analytical signal and maximum gain in the detector setting. A limit of detection (3σ) of 0.02 μg l -1 and relative standard deviation values close to 2% for 10 independent measurements of a 1 μg l -1 As solution were obtained. The sampling frequency increased from 45 to 102 h -1 with the subsequent saving in carrier gas used and reduction in wastes generated. The instrumental modification, which could be used for other elements currently determined by atomic fluorescence spectrometry, will permit hydride generators of more reduced dimensions to be constructed

  4. Simultaneous determination of arsenic and antimony by hydride generation atomic fluorescence spectrometry with dielectric barrier discharge atomizer

    Energy Technology Data Exchange (ETDEWEB)

    Xing Zhi [Department of Chemistry, Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry, Tsinghua University, Beijing 100084 (China); Kuermaiti, Biekesailike [Department of Chemistry, Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry, Tsinghua University, Beijing 100084 (China); Products Quality Inspection Institute, Yili, Xinjiang 835000 (China); Wang Juan; Han Guojun; Zhang Sichun [Department of Chemistry, Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry, Tsinghua University, Beijing 100084 (China); Zhang Xinrong, E-mail: xrzhang@mail.tsinghua.edu.cn [Department of Chemistry, Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry, Tsinghua University, Beijing 100084 (China)

    2010-12-15

    Simultaneous determination of As and Sb by hydride generation atomic fluorescence spectrometry was developed with the dielectric barrier discharge plasma as the hydride atomizer. The low-temperature and atmospheric-pressure micro-plasma was generated in a quartz cylindrical configuration device, which was constructed by an axial internal electrode and an outer electrode surrounding outside of the tube. The optimization of the atomizer construction and parameters for hydride generation and fluorescence detection systems were carried out. Under the optimized conditions, the detection limits for As and Sb were 0.04 and 0.05 {mu}g L{sup -1}, respectively. In addition, the applicability of the present method was confirmed by the detection of As and Sb in reference materials of quartz sandstone (GBW07106) and argillaceous limestone (GBW07108). The present work provided a new approach to exploit the miniaturized hydride generation dielectric barrier discharge atomic fluorescence spectrometry system for simultaneous multi-element determination.

  5. Simultaneous determination of arsenic and antimony by hydride generation atomic fluorescence spectrometry with dielectric barrier discharge atomizer

    International Nuclear Information System (INIS)

    Xing Zhi; Kuermaiti, Biekesailike; Wang Juan; Han Guojun; Zhang Sichun; Zhang Xinrong

    2010-01-01

    Simultaneous determination of As and Sb by hydride generation atomic fluorescence spectrometry was developed with the dielectric barrier discharge plasma as the hydride atomizer. The low-temperature and atmospheric-pressure micro-plasma was generated in a quartz cylindrical configuration device, which was constructed by an axial internal electrode and an outer electrode surrounding outside of the tube. The optimization of the atomizer construction and parameters for hydride generation and fluorescence detection systems were carried out. Under the optimized conditions, the detection limits for As and Sb were 0.04 and 0.05 μg L -1 , respectively. In addition, the applicability of the present method was confirmed by the detection of As and Sb in reference materials of quartz sandstone (GBW07106) and argillaceous limestone (GBW07108). The present work provided a new approach to exploit the miniaturized hydride generation dielectric barrier discharge atomic fluorescence spectrometry system for simultaneous multi-element determination.

  6. [Research on optimization of mathematical model of flow injection-hydride generation-atomic fluorescence spectrometry].

    Science.gov (United States)

    Cui, Jian; Zhao, Xue-Hong; Wang, Yan; Xiao, Ya-Bing; Jiang, Xue-Hui; Dai, Li

    2014-01-01

    Flow injection-hydride generation-atomic fluorescence spectrometry was a widely used method in the industries of health, environmental, geological and metallurgical fields for the merit of high sensitivity, wide measurement range and fast analytical speed. However, optimization of this method was too difficult as there exist so many parameters affecting the sensitivity and broadening. Generally, the optimal conditions were sought through several experiments. The present paper proposed a mathematical model between the parameters and sensitivity/broadening coefficients using the law of conservation of mass according to the characteristics of hydride chemical reaction and the composition of the system, which was proved to be accurate as comparing the theoretical simulation and experimental results through the test of arsanilic acid standard solution. Finally, this paper has put a relation map between the parameters and sensitivity/broadening coefficients, and summarized that GLS volume, carrier solution flow rate and sample loop volume were the most factors affecting sensitivity and broadening coefficients. Optimizing these three factors with this relation map, the relative sensitivity was advanced by 2.9 times and relative broadening was reduced by 0.76 times. This model can provide a theoretical guidance for the optimization of the experimental conditions.

  7. Automated system for on-line determination of dimethylarsinic and inorganic arsenic by hydride generation-atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Chaparro, L.L.; Leal, L.O. [Renewable Energy and Environmental Protection Department, Advanced Materials Research Center (CIMAV), Chihuahua, Chihuahua (Mexico); Ferrer, L.; Cerda, V. [University of the Balearic Islands, Department of Chemistry, Palma de Mallorca (Spain)

    2012-09-15

    A multisyringe flow-injection approach has been coupled to hydride generation-atomic fluorescence spectrometry (HG-AFS) with UV photo-oxidation for dimethylarsinic (DMA), inorganic As and total As determination, depending on the pre-treatment given to the sample (extraction or digestion). The implementation of a UV lamp allows on-line photo-oxidation of DMA and the following arsenic detection, whereas a bypass leads the flow directly to the HG-AFS system, performing inorganic arsenic determination. DMA concentration is calculated by the difference of total inorganic arsenic and measurement of the photo-oxidation step. The detection limits for DMA and inorganic arsenic were 0.09 and 0.47 {mu}g L{sup -1}, respectively. The repeatability values accomplished were of 2.4 and 1.8 %, whereas the injection frequencies were 24 and 28 injections per hour for DMA and inorganic arsenic, respectively. This method was validated by means of a solid reference material BCR-627 (muscle of tuna) with good agreement with the certified values. Satisfactory results for DMA and inorganic arsenic determination were obtained in several water matrices. The proposed method offers several advantages, such as increasing the sampling frequency, low detection limits and decreasing reagents and sample consumption, which leads to lower waste generation. (orig.)

  8. Antimony speciation analysis in sediment reference materials using high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    Potin-Gautier, M.; Pannier, F.; Quiroz, W.; Pinochet, H.; Gregori, I. de

    2005-01-01

    This work presents the development of suitable methodologies for determination of the speciation of antimony in sediment reference samples. Liquid chromatography with a post-column photo-oxidation step and hydride generation atomic fluorescence spectrometry as detection system is applied to the separation and determination of Sb(III), Sb(V) and trimethylantimony species. Post-column decomposition and hydride generation steps were studied for sensitive detection with the AFS detector. This method was applied to investigate the conditions under which speciation analysis of antimony in sediment samples can be carried out. Stability studies of Sb species during the extraction processes of solid matrices, using different reagents solutions, were performed. Results demonstrate that for the extraction yield and the stability of Sb species in different marine sediment extracts, citric acid in ascorbic acid medium was the best extracting solution for antimony speciation analysis in this matrix (between 55% and 65% of total Sb was recovered from CRMs, Sb(III) being the predominant species). The developed method allows the separation of the three compounds within 6 min with detection limits of 30 ng g -1 for Sb(III) and TMSbCl2 and 40 ng g -1 for Sb(V) in sediment samples

  9. Determination of arsenic speciation in sulfidic waters by Ion Chromatography Hydride-Generation Atomic Fluorescence Spectrometry (IC-HG-AFS).

    Science.gov (United States)

    Keller, Nicole S; Stefánsson, Andri; Sigfússon, Bergur

    2014-10-01

    A method for the analysis of arsenic species in aqueous sulfide samples is presented. The method uses an ion chromatography system connected with a Hydride-Generation Atomic Fluorescence Spectrometer (IC-HG-AFS). With this method inorganic As(III) and As(V) species in water samples can be analyzed, including arsenite (HnAs(III)O3(n-3)), thioarsenite (HnAs(III)S3(n-3)), arsenate (HnAs(V)O4(n-3)), monothioarsenate (HnAs(V)SO3(n-3)), dithioarsenate (HnAs(V)S2O2(n-3)), trithioarsenate (HnAs(V)S3O(n-3)) and tetrathioarsenate (HnAs(V)S4(n-3)). The peak identification and retention times were determined based on standard analysis of the various arsenic compounds. The analytical detection limit was ~1-3 µg L(-1) (LOD), depending on the quality of the baseline. This low detection limit makes this method also applicable to discriminate between waters meeting the drinking water standard of max. 10 µg L(-1) As, and waters that do not meet this standard. The new method was successfully applied for on-site determination of arsenic species in natural sulfidic waters, in which seven species were unambiguously identified. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Determination of arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid in cereals by hydride generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Matos Reyes, M.N. [Department of Analytical Chemistry, University of Valencia, 50 Dr. Moliner Street, 46100 Burjassot, Valencia (Spain); Department of Chemistry, Pontificia Universidade Catolica do Rio de Janeiro, Rua Marques de Sao Vicente, 225, 22453-900, Rio de Janeiro, RJ (Brazil); Cervera, M.L. [Department of Analytical Chemistry, University of Valencia, 50 Dr. Moliner Street, 46100 Burjassot, Valencia (Spain)], E-mail: m.luisa.cervera@uv.es; Campos, R.C. [Department of Chemistry, Pontificia Universidade Catolica do Rio de Janeiro, Rua Marques de Sao Vicente, 225, 22453-900, Rio de Janeiro, RJ (Brazil); Guardia, M. de la [Department of Analytical Chemistry, University of Valencia, 50 Dr. Moliner Street, 46100 Burjassot, Valencia (Spain)

    2007-09-15

    A fast, sensitive and simple non-chromatographic analytical method was developed for the speciation analysis of toxic arsenic species in cereal samples, namely rice and wheat semolina. An ultrasound-assisted extraction of the toxic arsenic species was performed with 1 mol L{sup -1} H{sub 3}PO{sub 4} and 0.1% (m/v) Triton XT-114. After extraction, As(III), As(V), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) concentrations were determined by hydride generation atomic fluorescence spectrometry using a series of proportional equations corresponding to four different experimental reduction conditions. The detection limits of the method were 1.3, 0.9, 1.5 and 0.6 ng g{sup -1} for As(III), As(V), DMA and MMA, respectively, expressed in terms of sample dry weight. Recoveries were always greater than 90%, and no species interconversion occurred. The speciation analysis of a rice flour reference material certified for total arsenic led to coherent results, which were also in agreement with other speciation studies made on the same certified reference material.

  11. Determination of Te in soldering tin using continuous flowing electrochemical hydride generation atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    Jiang Xianjuan; Gan Wuer; Han Suping; He Youzhao

    2008-01-01

    An electrochemical hydride generation system was developed for the detection of Te by coupling an electrochemical hydride generator with atomic fluorescence spectrometry. Since TeH 2 is unstable and easily decomposes in solution, a reticular W filament cathode was used in the present system. The TeH 2 generated on the cathode surface was effectively driven out by sweeping gas from the cathode chamber. In addition, a low temperature electrochemical cell (10 deg. C) was applied to reduce the decomposition of TeH 2 in solution. The limit of detection (LOD) was 2.2 ng ml -1 and the relative standard deviation (RSD) was 3.9% for nine consecutive measurements of standard solution. This method was successfully employed for determination of Te in soldering tin material

  12. Determination of cadmium in seawater by chelate vapor generation atomic fluorescence spectrometry

    Science.gov (United States)

    Sun, Rui; Ma, Guopeng; Duan, Xuchuan; Sun, Jinsheng

    2018-03-01

    A method for the determination of cadmium in seawater by chelate vapor generation (Che-VG) atomic fluorescence spectrometry is described. Several commercially available chelating agents, including ammonium pyrrolidine dithiocarbamate (APDC), sodium dimethyl dithiocarbamate (DMDTC), ammonium dibutyl dithiophosphate (DBDTP) and sodium O,O-diethyl dithiophosphate (DEDTP), are compared with sodium diethyldithiocarbamate (DDTC) for the Che-VG of cadmium, and results showed that DDTC and DEDTP had very good cadmium signal intensity. The effect of the conditions of Che-VG with DDTC on the intensity of cadmium signal was investigated. Under the optimal conditions, 85 ± 3% Che-VG efficiency is obtained for cadmium. The detection limit (3σ) obtained in the optimal conditions was 0.19 ng ml- 1. The relative standard deviation (RSD, %) for ten replicate determinations at 2 ng ml- 1 Cd was 3.42%. The proposed method was successfully applied to the ultratrace determination of cadmium in seawater samples by the standard addition method.

  13. Cloud point extraction for trace inorganic arsenic speciation analysis in water samples by hydride generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shan, E-mail: ls_tuzi@163.com; Wang, Mei, E-mail: wmei02@163.com; Zhong, Yizhou, E-mail: yizhz@21cn.com; Zhang, Zehua, E-mail: kazuki.0101@aliyun.com; Yang, Bingyi, E-mail: e_yby@163.com

    2015-09-01

    A new cloud point extraction technique was established and used for the determination of trace inorganic arsenic species in water samples combined with hydride generation atomic fluorescence spectrometry (HGAFS). As(III) and As(V) were complexed with ammonium pyrrolidinedithiocarbamate and molybdate, respectively. The complexes were quantitatively extracted with the non-ionic surfactant (Triton X-114) by centrifugation. After addition of antifoam, the surfactant-rich phase containing As(III) was diluted with 5% HCl for HGAFS determination. For As(V) determination, 50% HCl was added to the surfactant-rich phase, and the mixture was placed in an ultrasonic bath at 70 °C for 30 min. As(V) was reduced to As(III) with thiourea–ascorbic acid solution, followed by HGAFS. Under the optimum conditions, limits of detection of 0.009 and 0.012 μg/L were obtained for As(III) and As(V), respectively. Concentration factors of 9.3 and 7.9, respectively, were obtained for a 50 mL sample. The precisions were 2.1% for As(III) and 2.3% for As(V). The proposed method was successfully used for the determination of trace As(III) and As(V) in water samples, with satisfactory recoveries. - Highlights: • Cloud point extraction was firstly established to determine trace inorganic arsenic(As) species combining with HGAFS. • Separate As(III) and As(V) determinations improve the accuracy. • Ultrasonic release of complexed As(V) enables complete As(V) reduction to As(III). • Direct HGAFS analysis can be performed.

  14. Redox speciation analysis of antimony in soil extracts by hydride generation atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    Fuentes, Edwar; Pinochet, Hugo; Gregori, Ida de; Potin-Gautier, Martine

    2003-01-01

    A sensitive atomic spectrometric method for the redox speciation analysis of antimony in soils is described. The method is based on the selective generation of stibine from Sb(III) in a continuous flow system using atomic fluorescence spectrometry for detection. Sb(V) is masked by citric or oxalic acid in HCl medium. The procedure was optimized with synthetic solutions of Sb(III) and Sb(V). The effect of carboxylic acid and HCl concentration on the recovery of Sb(III) and Sb(V) species from standard solutions, and on the fluorescence signal were studied. Both species were extracted from soil with H 2 O, 0.05 mol l -1 EDTA and 0.25 mol l -1 H 2 SO 4 . Since the soil samples were collected from sites impacted by copper mining activities, the effect of Cu 2+ on the determination of antimony in synthetic solutions and soil extracts was studied. Cu 2+ decreased the Sb(III) signal, but had no effect on the total antimony determination. Therefore, the selective determination of Sb(III) was carried out in citric acid-HCl medium, using the analyte addition technique. Total antimony in soil extracts was determined using the standard calibration technique after reducing Sb(V) to Sb(III) at room temperature with KI-ascorbic acid. The Sb(V) concentration was calculated from the difference between total antimony and Sb(III). The limits of detection (PS Analytical, Excalibur Millennium model) were 17 and 10 ng l -1 for Sb(III) and total antimony, respectively, and the R.S.D. at the 0.5-μg l -1 level were 2.5 and 2.4%, respectively. The total antimony concentration of soils is in the mg kg -1 range; the Sb recovery from the different soils by the extracting solutions was between less than 0.02% and approximately 10%. Similar recoveries were obtained using EDTA and sulfuric acid solutions. Sb(V) was found to be the main antimony species extracted from soils

  15. Continuous flow hydride generation-atomic fluorescence spectrometric determination and speciation of arsenic in wine

    Energy Technology Data Exchange (ETDEWEB)

    Karadjova, Irina B. [Faculty of Chemistry, University of Sofia, 1 James Bourchier Blvd., Sofia 1164 (Bulgaria); Lampugnani, Leonardo [C.N.R. Istituto per i processi chimico-fisici, Area della Ricerca di Pisa, Via Moruzzi 1, 56124 Pisa (Italy)]. E-mail: lampugnani@ipcf.cnr.it; Onor, Massimo [C.N.R. Istituto per i processi chimico-fisici, Area della Ricerca di Pisa, Via Moruzzi 1, 56124 Pisa (Italy); D' Ulivo, Alessandro [C.N.R. Istituto per i processi chimico-fisici, Area della Ricerca di Pisa, Via Moruzzi 1, 56124 Pisa (Italy); Tsalev, Dimiter L. [Faculty of Chemistry, University of Sofia, 1 James Bourchier Blvd., Sofia 1164 (Bulgaria)

    2005-07-15

    Methods for the atomic fluorescence spectrometric (AFS) determination of total arsenic and arsenic species in wines based on continuous flow hydride generation (HG) with atomization in miniature diffusion flame (MDF) are described. For hydride-forming arsenic, L-cysteine is used as reagent for pre-reduction and complexation of arsenite, arsenate, monomethylarsonate and dimethylarsinate. Concentrations of hydrochloric acid and tetrahydroborate are optimized in order to minimize interference by ethanol. Procedure permits determination of the sum of these four species in 5-10-fold diluted samples with limit of detection (LOD) 0.3 and 0.6 {mu}g l{sup -1} As in white and red wines, respectively, with precision between 2% and 8% RSD at As levels within 0.5-10 {mu}g l{sup -1}. Selective arsine generation from different reaction media is used for non-chromatographic determination of arsenic species in wines: citrate buffer at pH 5.1 for As(III); 0.2 mol l{sup -1} acetic acid for arsenite + dimethylarsinate (DMA); 8 mol l{sup -1} HCl for total inorganic arsenic [As(III) + As(V)]; and monomethylarsonate (MMA) calculated by difference. Calibration with aqueous and ethanol-matched standard solutions of As(III) is used for 10- and 5-fold diluted samples, respectively. The LODs are 0.4 {mu}g l{sup -1} for As(III) and 0.3 {mu}g l{sup -1} for the other three As species and precision is within 4-8% RSDs. Arsenic species in wine were also determined by coupling of ion chromatographic separation on an anion exchange column and HG-flame AFS detection. Methods were validated by means of recovery studies and comparative analyses by HG-AFS and electrothermal atomic absorption spectrometry after microwave digestion. The LODs were 0.12, 0.27, 0.15 and 0.13 {mu}g l{sup -1} (as As) and RSDs were 2-6%, 5-9%, 3-7% and 2-5% for As(III), As(V), MMA and DMA arsenic species, respectively. Bottled red and white wines from Bulgaria, Republic of Macedonia and Italy were analyzed by non

  16. Continuous flow hydride generation-atomic fluorescence spectrometric determination and speciation of arsenic in wine

    International Nuclear Information System (INIS)

    Karadjova, Irina B.; Lampugnani, Leonardo; Onor, Massimo; D'Ulivo, Alessandro; Tsalev, Dimiter L.

    2005-01-01

    Methods for the atomic fluorescence spectrometric (AFS) determination of total arsenic and arsenic species in wines based on continuous flow hydride generation (HG) with atomization in miniature diffusion flame (MDF) are described. For hydride-forming arsenic, L-cysteine is used as reagent for pre-reduction and complexation of arsenite, arsenate, monomethylarsonate and dimethylarsinate. Concentrations of hydrochloric acid and tetrahydroborate are optimized in order to minimize interference by ethanol. Procedure permits determination of the sum of these four species in 5-10-fold diluted samples with limit of detection (LOD) 0.3 and 0.6 μg l -1 As in white and red wines, respectively, with precision between 2% and 8% RSD at As levels within 0.5-10 μg l -1 . Selective arsine generation from different reaction media is used for non-chromatographic determination of arsenic species in wines: citrate buffer at pH 5.1 for As(III); 0.2 mol l -1 acetic acid for arsenite + dimethylarsinate (DMA); 8 mol l -1 HCl for total inorganic arsenic [As(III) + As(V)]; and monomethylarsonate (MMA) calculated by difference. Calibration with aqueous and ethanol-matched standard solutions of As(III) is used for 10- and 5-fold diluted samples, respectively. The LODs are 0.4 μg l -1 for As(III) and 0.3 μg l -1 for the other three As species and precision is within 4-8% RSDs. Arsenic species in wine were also determined by coupling of ion chromatographic separation on an anion exchange column and HG-flame AFS detection. Methods were validated by means of recovery studies and comparative analyses by HG-AFS and electrothermal atomic absorption spectrometry after microwave digestion. The LODs were 0.12, 0.27, 0.15 and 0.13 μg l -1 (as As) and RSDs were 2-6%, 5-9%, 3-7% and 2-5% for As(III), As(V), MMA and DMA arsenic species, respectively. Bottled red and white wines from Bulgaria, Republic of Macedonia and Italy were analyzed by non-chromatographic and chromatographic procedures and the As

  17. Determination of arsenic species in seafood samples from the Aegean Sea by liquid chromatography-(photo-oxidation)-hydride generation-atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Schaeffer, Richard [Department of Applied Chemistry, Corvinus University, Villanyi ut 29-35, 1118 Budapest (Hungary); Soeroes, Csilla [Department of Applied Chemistry, Corvinus University, Villanyi ut 29-35, 1118 Budapest (Hungary); Ipolyi, Ildiko [Department of Applied Chemistry, Corvinus University, Villanyi ut 29-35, 1118 Budapest (Hungary); Fodor, Peter [Department of Applied Chemistry, Corvinus University, Villanyi ut 29-35, 1118 Budapest (Hungary); Thomaidis, Nikolaos S. [Laboratory of Analytical Chemistry, Department of Chemistry, University of Athens, Panepistiomopolis Zografou, 15776 Athens (Greece)]. E-mail: ntho@chem.uoa.gr

    2005-08-15

    In this study arsenic compounds were determined in mussels (Mytulis galloprovincialis), anchovies (Engraulis encrasicholus), sea-breams (Sparus aurata), sea bass (Dicentrarchus labrax) and sardines (Sardina pilchardus) collected from Aegean Sea using liquid chromatography-photo-oxidation-hydride generation-atomic fluorescence spectrometry [LC-(PO)-HG-AFS] system. Twelve arsenicals were separated and determined on the basis of their difference in two properties: (i) the pK {sub a} values and (ii) hydride generation capacity. The separation was carried out both with an anion- and a cation-exchange column, with and without photo-oxidation. In all the samples arsenobetaine, AB was detected as the major compound (concentrations ranging between 2.7 and 23.1 {mu}g g{sup -1} dry weight), with trace amounts of arsenite, As(III), dimethylarsinic acid, DMA and arsenocholine, AC, also present. Arsenosugars were detected only in the mussel samples (in concentrations of 0.9-3.6 {mu}g g{sup -1} dry weight), along with the presence of an unknown compound, which, based on its retention time on the anion-exchange column Hamilton PRP-X100 and a recent communication [E. Schmeisser, R. Raml, K.A. Francesconi, D. Kuehnelt, A. Lindberg, Cs. Soeroes, W. Goessler, Chem. Commun. 16 (2004) 1824], is supposed to be a thio-arsenic analogue.

  18. Hydride generation atomic fluorescence spectrometric determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter using multivariate optimization

    International Nuclear Information System (INIS)

    Moscoso-Perez, Carmen; Moreda-Pineiro, Jorge; Lopez-Mahia, Purificacion; Muniategui-Lorenzo, Soledad; Fernandez-Fernandez, Esther; Prada-Rodriguez, Dario

    2004-01-01

    A highly sensitive and simple method, based on hydride generation and atomic fluorescence detection, has been developed for the determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter samples. Atmospheric particulates matter was collected on glass fiber filters using a medium volume sampler (PM1 particulate matter). Two-level factorial designs have been used to optimise the hydride generation atomic fluorescence spectrometry (HG-AFS) procedure. The effects of several parameters affecting the hydride generation efficiency (hydrochloric acid, sodium tetrahydroborate and potassium iodide concentrations and flow rates) have been evaluated using a Plackett-Burman experimental design. In addition, parameters affecting the hydride measurement (delay, analysis and memory times) have been also investigated. The significant parameters obtained (sodium tetrahydroborate concentration, sodium tetrahydroborate flow rate and analysis time for As; hydrochloric acid concentration and sodium tetrahydroborate flow rate for Se(IV); and sodium tetrahydroborate concentration and sodium tetrahydroborate flow rate for Te(IV)) have been optimized by using 2 n + star central composite design. Hydrochloric acid concentration and sodium tetrahydroborate flow rate were the significant parameters obtained for Sb and Bi determination, respectively. Using a univariate approach these parameters were optimized. The accuracy of methods have been verified by using several certified reference materials: SRM 1648 (urban particulate matter) and SRM 1649a (urban dust). Detection limits in the range of 6 x 10 -3 to 0.2 ng m -3 have been achieved. The developed methods were applied to several atmospheric particulate matter samples corresponding to A Coruna city (NW Spain)

  19. Determination of total Sb,Se Te, and Bi and evaluation of their inorganic species in garlic by hydride-generation-atomic-fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Matos Reyes, M.N.; Cervera, M.L.; Guardia, M. de la [University of Valencia, Department of Analytical Chemistry, Burjassot, Valencia (Spain)

    2009-07-15

    A sensitive and simple analytical method has been developed for determination of Sb(III), Sb(V), Se(IV), Se(VI), Te(IV), Te(VI), and Bi(III) in garlic samples by using hydride-generation-atomic-fluorescence spectrometry (HG-AFS). The method is based on a single extraction of the inorganic species by sonication at room temperature with 1 mol L{sup -1} H{sub 2}SO{sub 4} and washing of the solid phase with 0.1% (w/v) EDTA, followed by measurement of the corresponding hydrides generated under two different experimental conditions directly and after a pre-reduction step. The limit of detection of the method was 0.7 ng g{sup -1} for Sb(III), 1.0 ng g{sup -1} for Sb(V), 1.3 ng g{sup -1} for Se(IV), 1.0 ng g{sup -1} for Se(VI), 1.1 ng g{sup -1} for Te(IV), 0.5 ng g{sup -1} for Te(VI), and 0.9 ng g{sup -1} for Bi(III), in all cases expressed in terms of sample dry weight. (orig.)

  20. A comparative evaluation of different ionic liquids for arsenic species separation and determination in wine varietals by liquid chromatography - hydride generation atomic fluorescence spectrometry.

    Science.gov (United States)

    Castro Grijalba, Alexander; Fiorentini, Emiliano F; Martinez, Luis D; Wuilloud, Rodolfo G

    2016-09-02

    The application of different ionic liquids (ILs) as modifiers for chromatographic separation and determination of arsenite [As(III)], arsenate [As(V)], dimethylarsonic acid (DMA) and monomethylarsonic acid (MMA) species in wine samples, by reversed-phase high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry detection (RP-HPLC-HG-AFS) was studied in this work. Several factors influencing the chromatographic separation of the As species, such as pH of the mobile phase, buffer solution concentration, buffer type, IL concentration and length of alkyl groups in ILs were evaluated. The complete separation of As species was achieved using a C18 column in isocratic mode with a mobile phase composed of 0.5% (v/v) 1-octyl-3-methylimidazolium chloride ([C8mim]Cl) and 5% (v/v) methanol at pH 8.5. A multivariate methodology was used to optimize the variables involved in AFS detection of As species after they were separated by HPLC. The ILs showed remarkable performance for the separation of As species, which was obtained within 18min with a resolution higher than 0.83. The limits of detection for As(III), As(V), MMA and DMA were 0.81, 0.89, 0.62 and 1.00μg As L(-1). The proposed method was applied for As speciation analysis in white and red wine samples originated from different grape varieties. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. [Cloud Point extraction for determination of mercury in Chinese herbal medicine by hydride generation atomic fluorescence spectrometry with optimization using Box-Behnken design].

    Science.gov (United States)

    Wang, Mei; Li, Shan; Zhou, Jian-dong; Xu, Ying; Long, Jun-biao; Yang, Bing-yi

    2014-08-01

    Cloud point extraction (CPE) is proposed as a pre-concentration procedure for the determination of Hg in Chinese herbal medicine samples by hydride generation-atomic fluorescence spectrometry (HG-AFS). Hg2+ was reacted with dithizone to form hydrophobic chelate under the condition of pH. Using Triton X-114, as surfactant, chelate was quantitatively extracted into small volume of the surfactant-rich phase by heating the solution in a water bath for 15 min and centrifuging. Four variables including pH, dithizone concentration, Triton X-114 concentration and equilibrium temperature (T) showed the significant effect on extraction efficiency of total Hg evaluated by single-factor experiment, and Box-Behnken design and response surface method- ology were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum extraction efficiency. The results showed that the binomial was used to fit the response to experimental levels of each variable. ALL linear, quadratic terms of four variables, and interactions between pH and Trion X-114, pH and di- thizone affected the response value(extraction efficiency) significantly at 5% level. The optimum extraction conditions were as follows: pH 5.1, Triton X-114 concentration of 1.16 g x L(-1), dithizone concentration of 4.87 mol x L(-1), and T 58.2 degrees C, the predicted value of fluorescence was 4528.74 under the optimum conditions, and the experimental value had only 2.1% difference with it. Under the conditions, fluorescence was linear to mercury concentration in the range of 1-5 microg x L(-1). The limit of detection obtained was 0.01247 microg x L(-1) with the relative standard deviations (R.S.D.) for six replicate determinations of 1.30%. The proposed method was successfully applied to determination of Hg in morindae Radix, Andrographitis and dried tangerine samples with the recoveries of 95.0%-100.0%. Apparently Box-Behnken design combined with

  2. Determination of inorganic arsenic in algae using bromine halogenation and on-line nonpolar solid phase extraction followed by hydride generation atomic fluorescence spectrometry.

    Science.gov (United States)

    Zhang, Weihong; Qi, Yuehan; Qin, Deyuan; Liu, Jixin; Mao, Xuefei; Chen, Guoying; Wei, Chao; Qian, Yongzhong

    2017-08-01

    Accurate, stable and fast analysis of toxic inorganic arsenic (iAs) in complicated and arsenosugar-rich algae matrix is always a challenge. Herein, a novel analytical method for iAs in algae was reported, using bromine halogenation and on-line nonpolar solid phase extraction (SPE) followed by hydride generation atomic fluorescence spectrometry (HG-AFS). The separation of iAs from algae was first performed by nonpolar SPE sorbent using Br - for arsenic halogenation. Algae samples were extracted with 1% perchloric acid. Then, 1.5mL extract was reduced by 1% thiourea, and simultaneously reacted (for 30min) with 50μL of 10% KBr for converting iAs to AsBr 3 after adding 3.5mL of 70% HCl to 5mL. A polystyrene (PS) resin cartridge was employed to retain arsenicals, which were hydrolyzed, eluted from the PS resin with H 2 O, and categorized as iAs. The total iAs was quantified by HG-AFS. Under optimum conditions, the spiked recoveries of iAs in real algae samples were in the 82-96% range, and the method achieved a desirable limit of detection of 3μgkg -1 . The inter-day relative standard deviations were 4.5% and 4.1% for spiked 100 and 500μgkg -1 respectively, which proved acceptable for this method. For real algae samples analysis, the highest presence of iAs was found in sargassum fusiforme, followed by kelp, seaweed and laver. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Evaluation of a hydride generation-atomic fluorescence system for the determination of arsenic using a dielectric barrier discharge atomizer

    International Nuclear Information System (INIS)

    Zhu Zhenli; Liu Jixin; Zhang Sichun; Na Xing; Zhang Xinrong

    2008-01-01

    A new atomizer based on atmospheric pressure dielectric barrier discharge (DBD) plasma was specially designed for atomic fluorescence spectrometry (AFS) in order to be applied to the measurement of arsenic. The characteristics of the DBD atomizer and the effects of different parameters (power, discharge gas, gas flow rate, and KBH 4 concentration) were discussed in the paper. The DBD atomizer shows the following features: (1) low operation temperature (between 44 and 70 deg. C, depending on the operation conditions); (2) low power consumption; (3) operation at atmospheric pressure. The detection limit of As(III) using hydride generation (HG) with the proposed DBD-AFS was 0.04 μg L -1 . The analytical results obtained by the present method for total arsenic in reference materials, orchard leaves (SRM 1571) and water samples GBW(E) 080390, agree well with the certified values. The present HG-DBD-AFS is more sensitive and reliable for the determination of arsenic. It is a very promising technique allowing for field arsenic analysis based on atomic spectrometry

  4. Arsenic fractionation in agricultural soil using an automated three-step sequential extraction method coupled to hydride generation-atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rosas-Castor, J.M. [Universidad Autónoma de Nuevo León, UANL, Facultad de Ciencias Químicas, Cd. Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66451 Nuevo León (Mexico); Group of Analytical Chemistry, Automation and Environment, University of Balearic Islands, Cra. Valldemossa km 7.5, 07122 Palma de Mallorca (Spain); Portugal, L.; Ferrer, L. [Group of Analytical Chemistry, Automation and Environment, University of Balearic Islands, Cra. Valldemossa km 7.5, 07122 Palma de Mallorca (Spain); Guzmán-Mar, J.L.; Hernández-Ramírez, A. [Universidad Autónoma de Nuevo León, UANL, Facultad de Ciencias Químicas, Cd. Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66451 Nuevo León (Mexico); Cerdà, V. [Group of Analytical Chemistry, Automation and Environment, University of Balearic Islands, Cra. Valldemossa km 7.5, 07122 Palma de Mallorca (Spain); Hinojosa-Reyes, L., E-mail: laura.hinojosary@uanl.edu.mx [Universidad Autónoma de Nuevo León, UANL, Facultad de Ciencias Químicas, Cd. Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66451 Nuevo León (Mexico)

    2015-05-18

    Highlights: • A fully automated flow-based modified-BCR extraction method was developed to evaluate the extractable As of soil. • The MSFIA–HG-AFS system included an UV photo-oxidation step for organic species degradation. • The accuracy and precision of the proposed method were found satisfactory. • The time analysis can be reduced up to eight times by using the proposed flow-based BCR method. • The labile As (F1 + F2) was <50% of total As in soil samples from As-contaminated-mining zones. - Abstract: A fully automated modified three-step BCR flow-through sequential extraction method was developed for the fractionation of the arsenic (As) content from agricultural soil based on a multi-syringe flow injection analysis (MSFIA) system coupled to hydride generation-atomic fluorescence spectrometry (HG-AFS). Critical parameters that affect the performance of the automated system were optimized by exploiting a multivariate approach using a Doehlert design. The validation of the flow-based modified-BCR method was carried out by comparison with the conventional BCR method. Thus, the total As content was determined in the following three fractions: fraction 1 (F1), the acid-soluble or interchangeable fraction; fraction 2 (F2), the reducible fraction; and fraction 3 (F3), the oxidizable fraction. The limits of detection (LOD) were 4.0, 3.4, and 23.6 μg L{sup −1} for F1, F2, and F3, respectively. A wide working concentration range was obtained for the analysis of each fraction, i.e., 0.013–0.800, 0.011–0.900 and 0.079–1.400 mg L{sup −1} for F1, F2, and F3, respectively. The precision of the automated MSFIA–HG-AFS system, expressed as the relative standard deviation (RSD), was evaluated for a 200 μg L{sup −1} As standard solution, and RSD values between 5 and 8% were achieved for the three BCR fractions. The new modified three-step BCR flow-based sequential extraction method was satisfactorily applied for arsenic fractionation in real agricultural

  5. Speciation of the immediately mobilisable As(III), As(V), MMA and DMA in river sediments by high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry following ultrasonic extraction

    International Nuclear Information System (INIS)

    Huerga, A.; Lavilla, I.; Bendicho, C.

    2005-01-01

    In this work, a fast method is developed for the speciation of As(III), As(V), MMA and DMA in the immediately mobilisable fraction of river sediments (i.e. water-soluble and phosphate-exchangeable) by high performance liquid chromatography-hydride generation-atomic fluorescence detection (HPLC-HG-AFD) after extraction using focused ultrasound. The influence of relevant parameters influencing an ion-pairing chromatographic separation following isocratic elution (i.e. amount of MeOH in the mobile phase, ion pair reagent concentration, pH, flow rate) was studied. Focused ultrasound transmitted from an ultrasonic probe provided the same extractable contents as conventional extraction with no changes in the species distribution. The effect of the drying step over extraction of As species was investigated. The following drying procedures were compared: freeze-, oven-, microwave- and air-drying. No influence of the drying operation on the water-extractable fraction was observed. However, freeze- and air-drying yielded significantly higher phosphate-extractable amounts of As(III) and As(V) as compared to oven and microwaves. Detection limits for the As species were in the range 1.3-4.1 ng/g for the water-soluble fraction and 1.6-4.8 ng/g for the phosphate buffer exchangeable fraction. The method was applied to the speciation of immediately mobilisable As(III), As(V), DMA and MMA in 11 sediment samples collected along the beds of the Louro River (southern Galicia, Spain)

  6. Non-chromatographic speciation analysis of mercury by flow injection on-line preconcentration in combination with chemical vapor generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Wu Hong [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Department of Chemistry, Xuzhou Normal University, Xuzhou 221116 (China); Jin Yan [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Han Weiying [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Miao, Qiang [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China); Bi Shuping [School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry and Key Laboratory of MOE for Life Science, Nanjing University, Nanjing 210093 (China)]. E-mail: bisp@nju.edu.cn

    2006-07-15

    A novel non-chromatographic approach for direct speciation of mercury, based on the selective retention inorganic mercury and methylmercury on the inner wall of a knotted reactor by using ammonium diethyl dithiophosphate and dithizone as complexing agents respectively, was developed for flow injection on-line sorption preconcentration coupled with chemical vapor generation non-dispersive atomic fluorescence spectrometry. With the sample pH kept at 2.0, the preconcentration of inorganic mercury on the inner walls of the knotted reactor was carried out based on the exclusive retention of Hg-DDP complex in the presence of methylmercury via on-line merging the sample solution with ammonium diethyl dithiophosphate solution, and selective preconcentration methylmercury was achieved with dithizone instead of ammonium diethyl dithiophosphate. A 15% (v/v) HCl was introduced to elute the retained mercury species and merge with KBH{sub 4} solution for atomic fluorescence spectrometry detection. Under the optimal experimental conditions, the sample throughputs of inorganic mercury and methylmercury were 30 and 20 h{sup -1} with the enhancement factors of 13 and 24. The detection limits were found to be 3.6 ng l{sup -1} for Hg{sup 2+} and 2.0 ng l{sup -1} for CH{sub 3}Hg{sup +}. The precisions (RSD) for the 11 replicate measurements of each 0.2 {mu}g l{sup -1} of Hg{sup 2+} and CH{sub 3}Hg{sup +} were 2.2% and 2.8%, respectively. The developed method was validated by the analysis of certified reference materials (simulated natural water, rice flour and pork) and by recovery measurements on spiked samples, and was applied to the determination of inorganic mercury and methylmercury in biological and environmental water samples.

  7. Non-chromatographic speciation analysis of mercury by flow injection on-line preconcentration in combination with chemical vapor generation atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    Wu Hong; Jin Yan; Han Weiying; Miao, Qiang; Bi Shuping

    2006-01-01

    A novel non-chromatographic approach for direct speciation of mercury, based on the selective retention inorganic mercury and methylmercury on the inner wall of a knotted reactor by using ammonium diethyl dithiophosphate and dithizone as complexing agents respectively, was developed for flow injection on-line sorption preconcentration coupled with chemical vapor generation non-dispersive atomic fluorescence spectrometry. With the sample pH kept at 2.0, the preconcentration of inorganic mercury on the inner walls of the knotted reactor was carried out based on the exclusive retention of Hg-DDP complex in the presence of methylmercury via on-line merging the sample solution with ammonium diethyl dithiophosphate solution, and selective preconcentration methylmercury was achieved with dithizone instead of ammonium diethyl dithiophosphate. A 15% (v/v) HCl was introduced to elute the retained mercury species and merge with KBH 4 solution for atomic fluorescence spectrometry detection. Under the optimal experimental conditions, the sample throughputs of inorganic mercury and methylmercury were 30 and 20 h -1 with the enhancement factors of 13 and 24. The detection limits were found to be 3.6 ng l -1 for Hg 2+ and 2.0 ng l -1 for CH 3 Hg + . The precisions (RSD) for the 11 replicate measurements of each 0.2 μg l -1 of Hg 2+ and CH 3 Hg + were 2.2% and 2.8%, respectively. The developed method was validated by the analysis of certified reference materials (simulated natural water, rice flour and pork) and by recovery measurements on spiked samples, and was applied to the determination of inorganic mercury and methylmercury in biological and environmental water samples

  8. Simultaneous determination of total arsenic and total selenium in Chinese medicinal herbs by hydride generation atomic fluorescence spectrometry in tartaric acid medium

    International Nuclear Information System (INIS)

    Liu Zhanfeng; Sun Hanwen; Shen Shigang; Li Liqing; Shi Hongmei

    2005-01-01

    By HG-AFS, a new method was proposed for simultaneous determination of total arsenic and total selenium existed in the Chinese medicinal herbs in tartaric acid medium. The effects of analytical conditions and coexisting ions on the fluorescence signal intensity of analytes were investigated. The proposed method was provided with linear response ranges above 22 μg l -1 for As and 44 μg l -1 for Se, and the detection limits of 0.13 and 0.12 μg l -1 were obtained for As and Se respectively. The recoveries of 93.8-96.1% for As and 95.3-99.1% for Se, and the precision of 1.2-3.8% and 2.4-5.3% (R.S.D., n = 8) respectively, were obtained via simultaneous determined four samples of Chinese medicinal herbs and three certified botanic reference materials successfully. The proposed method has the advantages of simple operation, high sensitivity and high efficiency

  9. Fluorescence detection of esophageal neoplasia

    Science.gov (United States)

    Borisova, E.; Vladimirov, B.; Avramov, L.

    2008-06-01

    White-light endoscopy is well-established and wide used modality. However, despite the many technological advances that have been occurred, conventional endoscopy is suboptimal and usually detects advanced stage lesions. The limitations of standard endoscopy initiate development of spectroscopic techniques, additional to standard endoscopic equipment. One of the most sensitive approaches is fluorescence spectroscopy of gastrointestinal mucosa for neoplasia detection. In the recent study delta-aminolevulinic acid/Protoporphyrin IX (5-ALA/PpIX) is used as fluorescent marker for dysplasia and tumor detection in esophagus. The 5-ALA is administered per os six hours before measurements at dose 20 mg/kg weight. Excitation source has max of emission at 405 nm and light is delivered by the standard light guide of the endoscopic equipment. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. Spectral features observed during endoscopic investigations could be distinct as the next regions: 450-630 nm region, where tissue autofluorescence is observed; 630-710 nm region, where fluorescence of PpIX is clearly pronounced; 530-580 nm region, where minima in the autofluorescence signal are observed, related to reabsorption of blood. The lack of fluorescence peaks in the red spectral area for normal mucosa is an indication for selective accumulation of 5-ALA/PpIX only in abnormal sites Very good correlation between fluorescence signals and histology examination of the lesions investigated is achieved.

  10. Fluorescence detection of dental calculus

    Science.gov (United States)

    Gonchukov, S.; Biryukova, T.; Sukhinina, A.; Vdovin, Yu

    2010-11-01

    This work is devoted to the optimization of fluorescence dental calculus diagnostics in optical spectrum. The optimal wavelengths for fluorescence excitation and registration are determined. Two spectral ranges 620 - 645 nm and 340 - 370 nm are the most convenient for supra- and subgingival calculus determination. The simple implementation of differential method free from the necessity of spectrometer using was investigated. Calculus detection reliability in the case of simple implementation is higher than in the case of spectra analysis at optimal wavelengths. The use of modulated excitation light and narrowband detection of informative signal allows us to decrease essentially its diagnostic intensity even in comparison with intensity of the low level laser dental therapy.

  11. Preconcentration and in-situ photoreduction of trace selenium using TiO2 nanoparticles, followed by its determination by slurry photochemical vapor generation atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    Yang, Wulin; Wu, Li; Zhu, Xiaofan; Gao, Ying; Hou, Xiandeng; Zheng, Chengbin

    2014-01-01

    We have developed a method for the determination of trace levels of total selenium in water samples. It integrates preconcentration, in-situ photoreduction and slurry photochemical vapor generation using TiO 2 nanoparticles, and the determination of total selenium by AFS. The Se(IV) and Se(VI) species were adsorbed on a slurry of TiO 2 nanoparticles which then were exposed to UV irradiation in the presence of formic acid to form volatile selenium species. The detection limits were improved 17-fold compared to hydride generation and 56-fold compared to photochemical vapor generation, both without any preconcentration. No significant difference was found in the limits of detection (LODs) for Se(IV) and Se(VI). The LOD is as low as 0.8 ng L −1 , the precision is better than 4.5 % (at a level of 0.1 μg L −1 of selenium). The method gave good recoveries when applied to the determination of total selenium in a certified tissue reference material (DORM-3) and in spiked drinking water and wastewater samples containing high concentrations of transition and noble metal ions. It also excels by very low LODs, a significant enhancement of sample throughput, reduced reagent consumption and sample loss, and minimal interference by transition and noble metal ions. (author)

  12. Fluorescence detection of dental calculus

    International Nuclear Information System (INIS)

    Gonchukov, S; Sukhinina, A; Vdovin, Yu; Biryukova, T

    2010-01-01

    This work is devoted to the optimization of fluorescence dental calculus diagnostics in optical spectrum. The optimal wavelengths for fluorescence excitation and registration are determined. Two spectral ranges 620 – 645 nm and 340 – 370 nm are the most convenient for supra- and subgingival calculus determination. The simple implementation of differential method free from the necessity of spectrometer using was investigated. Calculus detection reliability in the case of simple implementation is higher than in the case of spectra analysis at optimal wavelengths. The use of modulated excitation light and narrowband detection of informative signal allows us to decrease essentially its diagnostic intensity even in comparison with intensity of the low level laser dental therapy

  13. Fluorescence detection system for microfluidic droplets

    Science.gov (United States)

    Chen, Binyu; Han, Xiaoming; Su, Zhen; Liu, Quanjun

    2018-05-01

    In microfluidic detection technology, because of the universality of optical methods in laboratory, optical detection is an attractive solution for microfluidic chip laboratory equipment. In addition, the equipment with high stability and low cost can be realized by integrating appropriate optical detection technology on the chip. This paper reports a detection system for microfluidic droplets. Photomultiplier tubes (PMT) is used as a detection device to improve the sensitivity of detection. This system improves the signal to noise ratio by software filtering and spatial filter. The fluorescence intensity is proportional to the concentration of the fluorescence and intensity of the laser. The fluorescence micro droplets of different concentrations can be distinguished by this system.

  14. Molecules for Fluorescence Detection of Specific Chemicals

    Science.gov (United States)

    Fedor, Steve

    2008-01-01

    A family of fluorescent dye molecules has been developed for use in on-off fluorescence detection of specific chemicals. By themselves, these molecules do not fluoresce. However, when exposed to certain chemical analytes in liquid or vapor forms, they do fluoresce (see figure). These compounds are amenable to fixation on or in a variety of substrates for use in fluorescence-based detection devices: they can be chemically modified to anchor them to porous or non-porous solid supports or can be incorporated into polymer films. Potential applications for these compounds include detection of chemical warfare agents, sensing of acidity or alkalinity, and fluorescent tagging of proteins in pharmaceutical research and development. These molecules could also be exploited for use as two-photon materials for photodynamic therapy in the treatment of certain cancers and other diseases. A molecule in this family consists of a fluorescent core (such as an anthracene or pyrene) attached to two end groups that, when the dye is excited by absorption of light, transfer an electron to the core, thereby quenching the fluorescence. The end groups can be engineered so that they react chemically with certain analytes. Upon reaction, electrons on the end groups are no longer available for transfer to the core and, consequently, the fluorescence from the core is no longer quenched. The chemoselectivity of these molecules can be changed by changing the end groups. For example, aniline end groups afford a capability for sensing acids or acid halides (including those contained in chemical warfare agents). Pyridine or bipyridyl end groups would enable sensing of metal ions. Other chemicals that can be selectively detected through suitable choice of end groups include glucose and proteins. Moreover, the fluorescent cores can be changed to alter light-absorption and -emission characteristics: anthracene cores fluoresce at wavelengths around 500 nm, whereas perylene cores absorb and emit at

  15. Detection of Counterfeit Tequila by Fluorescence Spectroscopy

    Directory of Open Access Journals (Sweden)

    José Manuel de la Rosa Vázquez

    2015-01-01

    Full Text Available An ultraviolet (UV light induced fluorescence study to discriminate fake tequila from genuine ones is presented. A portable homemade system based on four light emitting diodes (LEDs from 255 to 405 nm and a miniature spectrometer was used. It has been shown that unlike fake and silver tequila, which produce weak fluorescence signal, genuine mixed, rested, and aged tequilas show high fluorescence emission in the range from 400 to 750 nm. The fluorescence intensity grows with aging in 100% agave tequila. Such fluorescence differences can even be observed with naked eyes. The presented results demonstrate that the fluorescence measurement could be a good method to detect counterfeit tequila.

  16. 21 CFR 872.1745 - Laser fluorescence caries detection device.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Laser fluorescence caries detection device. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.1745 Laser fluorescence caries detection device. (a) Identification. A laser fluorescence caries detection device is a laser, a...

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

    Indian Academy of Sciences (India)

    Yan-Fei Kang

    A fluorescent probe, with simplicity of structure and convenience of synthesis, is capable of detecting ... Yan-Fei Kang et al. .... Pastore A, Federici G, Bertini E and Ptemonte F 2003 ... Urano Y 2010 New Strategies for Fluorescent Probe.

  18. Using Fluorescent Viruses for Detecting Bacteria in Water

    Science.gov (United States)

    Tabacco, Mary Beth; Qian, Xiaohua; Russo, Jaimie A.

    2009-01-01

    A method of detecting water-borne pathogenic bacteria is based partly on established molecular-recognition and fluorescent-labeling concepts, according to which bacteria of a species of interest are labeled with fluorescent reporter molecules and the bacteria can then be detected by fluorescence spectroscopy. The novelty of the present method lies in the use of bacteriophages (viruses that infect bacteria) to deliver the fluorescent reporter molecules to the bacteria of the species of interest.

  19. Optimal Fluorescence Waveband Determination for Detecting Defective Cherry Tomatoes Using a Fluorescence Excitation-Emission Matrix

    Directory of Open Access Journals (Sweden)

    In-Suck Baek

    2014-11-01

    Full Text Available A multi-spectral fluorescence imaging technique was used to detect defective cherry tomatoes. The fluorescence excitation and emission matrix was used to measure for defects, sound surface and stem areas to determine the optimal fluorescence excitation and emission wavelengths for discrimination. Two-way ANOVA revealed the optimal excitation wavelength for detecting defect areas was 410 nm. Principal component analysis (PCA was applied to the fluorescence emission spectra of all regions at 410 nm excitation to determine the emission wavelengths for defect detection. The major emission wavelengths were 688 nm and 506 nm for the detection. Fluorescence images combined with the determined emission wavebands demonstrated the feasibility of detecting defective cherry tomatoes with >98% accuracy. Multi-spectral fluorescence imaging has potential utility in non-destructive quality sorting of cherry tomatoes.

  20. Fluorescence immunoassay for detecting periodontal bacterial pathogens in plaque.

    OpenAIRE

    Wolff, L F; Anderson, L; Sandberg, G P; Aeppli, D M; Shelburne, C E

    1991-01-01

    A particle concentration fluorescence immunoassay has been modified into a bacterial concentration fluorescence immunoassay (BCFIA) to rapidly detect periodontopathic bacteria in human plaque samples. The BCFIA utilizes fluorescently tagged monoclonal antibodies (MAbs) directed against the lipopolysaccharide of selected gram-negative plaque bacteria. Microorganisms closely associated with periodontal disease that can be identified in plaque with the BCFIA include Porphyromonas gingivalis, Bac...

  1. Dual-detection confocal fluorescence microscopy: fluorescence axial imaging without axial scanning.

    Science.gov (United States)

    Lee, Dong-Ryoung; Kim, Young-Duk; Gweon, Dae-Gab; Yoo, Hongki

    2013-07-29

    We propose a new method for high-speed, three-dimensional (3-D) fluorescence imaging, which we refer to as dual-detection confocal fluorescence microscopy (DDCFM). In contrast to conventional beam-scanning confocal fluorescence microscopy, where the focal spot must be scanned either optically or mechanically over a sample volume to reconstruct a 3-D image, DDCFM can obtain the depth of a fluorescent emitter without depth scanning. DDCFM comprises two photodetectors, each with a pinhole of different size, in the confocal detection system. Axial information on fluorescent emitters can be measured by the axial response curve through the ratio of intensity signals. DDCFM can rapidly acquire a 3-D fluorescent image from a single two-dimensional scan with less phototoxicity and photobleaching than confocal fluorescence microscopy because no mechanical depth scans are needed. We demonstrated the feasibility of the proposed method by phantom studies.

  2. Sensitive turn-on fluorescent detection of tartrazine based on fluorescence resonance energy transfer.

    Science.gov (United States)

    Huang, Sheng Tian; Shi, Yan; Li, Nian Bing; Luo, Hong Qun

    2012-01-18

    We introduce a sensitive, rapid, label-free and general fluorescent method for the determination of tartrazine by competitive binding to reduced graphene oxide (rGO) against fluorescein, and the fluorescence recovery upon fluorescein desorption from rGO provides a quantitative readout for tartrazine, giving a detection limit of 0.53 ng mL(-1).

  3. Tomato seeds maturity detection system based on chlorophyll fluorescence

    Science.gov (United States)

    Li, Cuiling; Wang, Xiu; Meng, Zhijun

    2016-10-01

    Chlorophyll fluorescence intensity can be used as seed maturity and quality evaluation indicator. Chlorophyll fluorescence intensity of seed coats is tested to judge the level of chlorophyll content in seeds, and further to judge the maturity and quality of seeds. This research developed a detection system of tomato seeds maturity based on chlorophyll fluorescence spectrum technology, the system included an excitation light source unit, a fluorescent signal acquisition unit and a data processing unit. The excitation light source unit consisted of two high power LEDs, two radiators and two constant current power supplies, and it was designed to excite chlorophyll fluorescence of tomato seeds. The fluorescent signal acquisition unit was made up of a fluorescence spectrometer, an optical fiber, an optical fiber scaffolds and a narrowband filter. The data processing unit mainly included a computer. Tomato fruits of green ripe stage, discoloration stage, firm ripe stage and full ripe stage were harvested, and their seeds were collected directly. In this research, the developed tomato seeds maturity testing system was used to collect fluorescence spectrums of tomato seeds of different maturities. Principal component analysis (PCA) method was utilized to reduce the dimension of spectral data and extract principal components, and PCA was combined with linear discriminant analysis (LDA) to establish discriminant model of tomato seeds maturity, the discriminant accuracy was greater than 90%. Research results show that using chlorophyll fluorescence spectrum technology is feasible for seeds maturity detection, and the developed tomato seeds maturity testing system has high detection accuracy.

  4. Phenylethynylpyrene excimer forming hybridization probes for fluorescence SNP detection

    DEFF Research Database (Denmark)

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

    2009-01-01

    Excimer formation is a unique feature of some fluorescent dyes (e.g., pyrene) which can be used for probing the proximity of biomolecules. Pyrene excimer fluorescence has previously been used for homogeneous detection of single nucleotide polymorphism (SNP) on DNA. 1-Phenylethynylpyrene (1-1-PEPy...

  5. Detection of rheumatoid arthritis in humans by fluorescence imaging

    Science.gov (United States)

    Ebert, Bernd; Dziekan, Thomas; Weissbach, Carmen; Mahler, Marianne; Schirner, Michael; Berliner, Birgitt; Bauer, Daniel; Voigt, Jan; Berliner, Michael; Bahner, Malte L.; Macdonald, Rainer

    2010-02-01

    The blood pool agent indo-cyanine green (ICG) has been investigated in a prospective clinical study for detection of rheumatoid arthritis using fluorescence imaging. Temporal behavior as well as spatial distribution of fluorescence intensity are suited to differentiate healthy and inflamed finger joints after i.v. injection of an ICG bolus.

  6. Design of Fluorescent Compounds for Scintillation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Pla-Dalmau, Anna [Northern Illinois U.

    1990-01-01

    Plastic scintillation detectors for high energy physics applications require the development of new fluorescent compounds to meet the demands set by the future generation of particle accelerators such as the Superconducting Supercollider (SSe). Plastic scintillators are commonly based on a polymer matrix doped with two fluorescent compounds: the primary dopant and the wavelength shifter. Their main characteristics are fast response time and high quantum efficiency. The exposure to larger radiation doses and demands for larger light output questions their survivability in the future experiments. A new type of plastic scintillator - intrinsic scintillator - has been suggested. It uses a single dopant as primary and wavelength shifter, and should be less susceptible to radiation damage....

  7. Dynamic fluorescence imaging with molecular agents for cancer detection

    Science.gov (United States)

    Kwon, Sun Kuk

    Non-invasive dynamic optical imaging of small animals requires the development of a novel fluorescence imaging modality. Herein, fluorescence imaging is demonstrated with sub-second camera integration times using agents specifically targeted to disease markers, enabling rapid detection of cancerous regions. The continuous-wave fluorescence imaging acquires data with an intensified or an electron-multiplying charge-coupled device. The work presented in this dissertation (i) assessed dose-dependent uptake using dynamic fluorescence imaging and pharmacokinetic (PK) models, (ii) evaluated disease marker availability in two different xenograft tumors, (iii) compared the impact of autofluorescence in fluorescence imaging of near-infrared (NIR) vs. red light excitable fluorescent contrast agents, (iv) demonstrated dual-wavelength fluorescence imaging of angiogenic vessels and lymphatics associated with a xenograft tumor model, and (v) examined dynamic multi-wavelength, whole-body fluorescence imaging with two different fluorescent contrast agents. PK analysis showed that the uptake of Cy5.5-c(KRGDf) in xenograft tumor regions linearly increased with doses of Cy5.5-c(KRGDf) up to 1.5 nmol/mouse. Above 1.5 nmol/mouse, the uptake did not increase with doses, suggesting receptor saturation. Target to background ratio (TBR) and PK analysis for two different tumor cell lines showed that while Kaposi's sarcoma (KS1767) exhibited early and rapid uptake of Cy5.5-c(KRGDf), human melanoma tumors (M21) had non-significant TBR differences and early uptake rates similar to the contralateral normal tissue regions. The differences may be due to different compartment location of the target. A comparison of fluorescence imaging with NIR vs. red light excitable fluorescent dyes demonstrates that NIR dyes are associated with less background signal, enabling rapid tumor detection. In contrast, animals injected with red light excitable fluorescent dyes showed high autofluorescence. Dual

  8. A fluorescence quenching test for the detection of flavonoid transformation.

    Science.gov (United States)

    Schoefer, L; Braune, A; Blaut, M

    2001-11-13

    A novel fluorescence quenching test for the detection of flavonoid degradation by microorganisms was developed. The test is based on the ability of the flavonoids to quench the fluorescence of 1,6-diphenyl-1,3,5-hexatriene (DPH). Several members of the anthocyanidins, flavones, isoflavones, flavonols, flavanones, dihydroflavanones, chalcones, dihydrochalcones and catechins were tested with regard to their quenching properties. The anthocyanidins were the most potent quenchers of DPH fluorescence, while the flavanones, dihydroflavanones and dihydrochalcones, quenched the fluorescence only weakly. The catechins had no visible impact on DPH fluorescence. The developed test allows a quick and easy differentiation between flavonoid-degrading and flavonoid-non-degrading bacteria. The investigation of individual reactions of flavonoid transformation with the developed test system is also possible.

  9. Smart phone based bacterial detection using bio functionalized fluorescent nanoparticles

    International Nuclear Information System (INIS)

    Rajendran, Vinoth Kumar; Bakthavathsalam, Padmavathy; Ali, Baquir Mohammed Jaffar

    2014-01-01

    We are describing immunochromatographic test strips with smart phone-based fluorescence readout. They are intended for use in the detection of the foodborne bacterial pathogens Salmonella spp. and Escherichia coli O157. Silica nanoparticles (SiNPs) were doped with FITC and Ru(bpy), conjugated to the respective antibodies, and then used in a conventional lateral flow immunoassay (LFIA). Fluorescence was recorded by inserting the nitrocellulose strip into a smart phone-based fluorimeter consisting of a light weight (40 g) optical module containing an LED light source, a fluorescence filter set and a lens attached to the integrated camera of the cell phone in order to acquire high-resolution fluorescence images. The images were analysed by exploiting the quick image processing application of the cell phone and enable the detection of pathogens within few minutes. This LFIA is capable of detecting pathogens in concentrations as low as 10 5 cfu mL −1 directly from test samples without pre-enrichment. The detection is one order of magnitude better compared to gold nanoparticle-based LFIAs under similar condition. The successful combination of fluorescent nanoparticle-based pathogen detection by LFIAs with a smart phone-based detection platform has resulted in a portable device with improved diagnosis features and having potential application in diagnostics and environmental monitoring. (author)

  10. Recent development of fluorescent imaging for specific detection of tumors

    International Nuclear Information System (INIS)

    Nakata, Eiji; Morii, Takashi; Uto, Yoshihiro; Hori, Hitoshi

    2011-01-01

    Increasing recent studies on fluorescent imaging for specific detection of tumors are described here on strategies of molecular targeting, metabolic specificity and hypoxic circumstance. There is described an instance of a conjugate of antibody and pH-activable fluorescent ligand, which specifically binds to the tumor cells, is internalized in the cellular lysozomes where their pH is low, and then is activated to become fluorescent only in viable tumor cells. For the case of metabolic specificity, excessive loading of the precursor (5-aminolevulinic acid) of protoporphyrin IX (ppIX), due to their low activity to convert ppIX to heme B, results in making tumors observable in red as ppIX emits fluorescence (red, 585 nm) when excited by blue ray of 410 nm. Similarly, imaging with indocyanine green which is accumulated in hepatoma cells is reported in success in detection of small lesion and metastasis when the dye is administered during operation. Reductive reactions exceed in tumor hypoxic conditions, of which feature is usable for imaging. Conjugates of nitroimidazole and fluorescent dye are reported to successfully image tumors by nitro reduction. Authors' UTX-12 is a non-fluorescent nitroaromatic derivative of pH-sensitive fluorescent dye seminaphtharhodafluor (SNARF), and is designed for the nitro group, the hypoxia-responding sensor, to be reduced in tumor hypoxic conditions and then for the aromatic moiety to be cleaved to release free SNARF. Use of hypoxia-inducible factor-1 (HIF-1) for imaging has been also reported in many. As above, studies on fluorescent imaging for specific detection of tumors are mostly at fundamental step but its future is conceivably promising along with advances in other technology like fluorescent endoscopy and multimodal imaging. (author)

  11. Characteristics of subgingival calculus detection by multiphoton fluorescence microscopy

    Science.gov (United States)

    Tung, Oi-Hong; Lee, Shyh-Yuan; Lai, Yu-Lin; Chen, How-Foo

    2011-06-01

    Subgingival calculus has been recognized as a major cause of periodontitis, which is one of the main chronic infectious diseases of oral cavities and a principal cause of tooth loss in humans. Bacteria deposited in subgingival calculus or plaque cause gingival inflammation, function deterioration, and then periodontitis. However, subgingival calculus within the periodontal pocket is a complicated and potentially delicate structure to be detected with current dental armamentaria, namely dental x-rays and dental probes. Consequently, complete removal of subgingival calculus remains a challenge to periodontal therapies. In this study, the detection of subgingival calculus employing a multiphoton autofluorescence imaging method was characterized in comparison with a one-photon confocal fluorescence imaging technique. Feasibility of such a system was studied based on fluorescence response of gingiva, healthy teeth, and calculus with and without gingiva covered. The multiphoton fluorescence technology perceived the tissue-covered subgingival calculus that cannot be observed by the one-photon confocal fluorescence method.

  12. Two-photon excited UV fluorescence for protein crystal detection

    International Nuclear Information System (INIS)

    Madden, Jeremy T.; DeWalt, Emma L.; Simpson, Garth J.

    2011-01-01

    Complementary measurements using SONICC and TPE-UVF allow the sensitive and selective detection of protein crystals. Two-photon excited ultraviolet fluorescence (TPE-UVF) microscopy is explored for sensitive protein-crystal detection as a complement to second-order nonlinear optical imaging of chiral crystals (SONICC). Like conventional ultraviolet fluorescence (UVF), TPE-UVF generates image contrast based on the intrinsic fluorescence of aromatic residues, generally producing higher fluorescence emission within crystals than the mother liquor by nature of the higher local protein concentration. However, TPE-UVF has several advantages over conventional UVF, including (i) insensitivity to optical scattering, allowing imaging in turbid matrices, (ii) direct compatibility with conventional optical plates and windows by using visible light for excitation, (iii) elimination of potentially damaging out-of-plane UV excitation, (iv) improved signal to noise through background reduction from out-of-plane excitation and (v) relatively simple integration into instrumentation developed for SONICC

  13. 5-ALA/PpIX fluorescence detection of gastrointestinal neoplasia

    Science.gov (United States)

    Borisova, Ekaterina G.; Vladimirov, Borislav; Terziev, Ivan; Ivanova, Radina; Avramov, Latchezar

    2009-07-01

    In the recent study delta-ALA/PpIX is used as fluorescent marker for dysplasia and tumor detection in esophagus, stomach and colon. ALA is administered per os six to eight (depending on the lesion location) hours before measurements at dose 20mg/kg weight. High-power light-emitting diode at 405 nm is used as an excitation source. Special opto-mechanical device is built for the LED to use the light guide of standard video-endoscopic system. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. The fluorescence detected from tumor sites has very complex spectral origins. It consists of autofluorescence, fluorescence from exogenous fluorophores and re-absorption from the chromophores accumulated in the tissue investigated. Spectral features observed during endoscopic investigations could be distinct as the next regions: 450-630 nm region, where tissue autofluorescence is observed; 630-710 nm region, where fluorescence of PpIX is clearly pronounced; 530-580 nm region, where minima in the autofluorescence signal are observed, related to re-absorption of oxy-hemoglobin in this spectral area. Endogenous and exogenous fluorescence spectra are used to develop simple but effective algorithm, based on dimensionless ratio of the signals at 560 and 635 nm, for differentiation of normal/abnormal gastrointestinal tissues. Very good correlation between fluorescence signals and histology examination of the lesions investigated is achieved.

  14. Satellite-detected fluorescence reveals global physiology of ocean phytoplankton

    Directory of Open Access Journals (Sweden)

    M. J. Behrenfeld

    2009-05-01

    Full Text Available Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we evaluate the physiological underpinnings of global variations in satellite-based phytoplankton chlorophyll fluorescence. The three dominant factors influencing fluorescence distributions are chlorophyll concentration, pigment packaging effects on light absorption, and light-dependent energy-quenching processes. After accounting for these three factors, resultant global distributions of quenching-corrected fluorescence quantum yields reveal a striking consistency with anticipated patterns of iron availability. High fluorescence quantum yields are typically found in low iron waters, while low quantum yields dominate regions where other environmental factors are most limiting to phytoplankton growth. Specific properties of photosynthetic membranes are discussed that provide a mechanistic view linking iron stress to satellite-detected fluorescence. Our results present satellite-based fluorescence as a valuable tool for evaluating nutrient stress predictions in ocean ecosystem models and give the first synoptic observational evidence that iron plays an important role in seasonal phytoplankton dynamics of the Indian Ocean. Satellite fluorescence may also provide a path for monitoring climate-phytoplankton physiology interactions and improving descriptions of phytoplankton light use efficiencies in ocean productivity models.

  15. Performance evaluation of spot detection algorithms in fluorescence microscopy images

    CSIR Research Space (South Africa)

    Mabaso, M

    2012-10-01

    Full Text Available triggered the development of a highly sophisticated imaging tool known as fluorescence microscopy. This is used to visualise and study intracellular processes. The use of fluorescence microscopy and a specific staining method make biological molecules... was first used in astronomical applications [2] to detect isotropic objects, and was then introduced to biological applications [3]. Olivio-Marin[3] approached the problem of feature extraction based on undecimated wavelet representation of the image...

  16. Detection of Salmonella typhi utilizing bioconjugated fluorescent polymeric nanoparticles

    International Nuclear Information System (INIS)

    Jain, Swati; Chattopadhyay, Sruti; Jackeray, Richa; Abid, Zainul; Singh, Harpal

    2016-01-01

    Present work demonstrates effective utilization of functionalized polymeric fluorescent nanoparticles as biosensing probe for the detection of Salmonella typhi bacteria on modified polycarbonate (PC) filters in about 3 h. Antibody modified-PC membranes were incubated with contaminated bacterial water for selective capturing which were detected by synthesized novel bioconjugate probe. Core–shell architecture of polymeric nanoparticles endows them with aqueous stabilization and keto-enolic functionalities making them usable for covalently linking S. typhi antibodies without any crosslinker or activator. Bradford analysis revealed that one nanoparticle has an average of 3.51 × 10"−"1"9 g or 21 × 10"4 bound S. typhi Ab molecules. Analysis of the regions of interest (ROI) in fluorescent micrographs of modified fluoroimmunoassay showed higher detection sensitivity of 5 × 10"2 cells/mL due to signal amplification unlike conventional naked dye FITC-Ab conjugate. Fluorescence of pyrene dye remained same on immobilization of biomolecules and nanoparticles showed stable fluorescent intensity under prolong exposure to laser owing to protective polymeric layer allowing accurate identification of bacteria. Surface-functionalized PC matrix and fluorescent label NPs permit covalent interactions among biomolecules enhancing signal acquisitions showing higher detection efficiency as compared to conventional microtiter plate-based system. Our novel immunoassay has the potential to be explored as rapid detection method for identifying S. typhi contaminations in water.Graphical Abstract

  17. Detection of Salmonella typhi utilizing bioconjugated fluorescent polymeric nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Swati, E-mail: swatijain.iitd@gmail.com; Chattopadhyay, Sruti, E-mail: sruticiitd@gmail.com; Jackeray, Richa; Abid, Zainul; Singh, Harpal, E-mail: harpal2000@yahoo.com [Centre for Biomedical Engineering, Indian Institute of Technology-Delhi (India)

    2016-05-15

    Present work demonstrates effective utilization of functionalized polymeric fluorescent nanoparticles as biosensing probe for the detection of Salmonella typhi bacteria on modified polycarbonate (PC) filters in about 3 h. Antibody modified-PC membranes were incubated with contaminated bacterial water for selective capturing which were detected by synthesized novel bioconjugate probe. Core–shell architecture of polymeric nanoparticles endows them with aqueous stabilization and keto-enolic functionalities making them usable for covalently linking S. typhi antibodies without any crosslinker or activator. Bradford analysis revealed that one nanoparticle has an average of 3.51 × 10{sup −19} g or 21 × 10{sup 4} bound S. typhi Ab molecules. Analysis of the regions of interest (ROI) in fluorescent micrographs of modified fluoroimmunoassay showed higher detection sensitivity of 5 × 10{sup 2} cells/mL due to signal amplification unlike conventional naked dye FITC-Ab conjugate. Fluorescence of pyrene dye remained same on immobilization of biomolecules and nanoparticles showed stable fluorescent intensity under prolong exposure to laser owing to protective polymeric layer allowing accurate identification of bacteria. Surface-functionalized PC matrix and fluorescent label NPs permit covalent interactions among biomolecules enhancing signal acquisitions showing higher detection efficiency as compared to conventional microtiter plate-based system. Our novel immunoassay has the potential to be explored as rapid detection method for identifying S. typhi contaminations in water.Graphical Abstract.

  18. Fluorescence detection of oral squamous cell carcinoma using Hyperflav

    Science.gov (United States)

    Melnik, Ivan S.; Dets, Sergiy M.; Rawicz, Andrew H.; Zhang, Lewei

    2000-05-01

    A novel hypericin-based drug HyperflavTM has been evaluated for light-induced fluorescence detection of oral cancer. Squamous cell carcinoma was induced with carcinogenic agent in right pouches of forty hamsters (20/20 males/females). Solution of HyperflavTM was sprinkled into stomach with a single dose 0.2 - 4 mg of pure hypericin per kg b.w. and 4 - 8 hours before fluorescence analysis. In two animal groups with cancer symptoms the autofluorescence and hypericin-induced fluorescence were taken under 442 nm excitation. The buccal mucosa and adjacent areas were measured fiberoptically in-vivo and in-vitro using orange/green ratio (610/540). The in-vivo fluorescence imaging of malignant areas was conducted to assist the biopsy guidance and to compare with white-light images. Histological and morphological analyses were performed from biopsies. Oral squamous cell carcinoma in its early stage demonstrated specific higher 610/540 ratio for 37 tested hamsters. Advanced state involved another higher fluorescence maximum around 640 nm that in our opinion caused by strong porphyrin-induced native fluorescence. Such deformation of fluorescence spectra may lead to inadequate perception of diseased tissue area. To avoid this problem the autofluorescence spectra & images were added. HyperflavTM application is promising for demarcation of early oral cancer when combined with autofluorescence measurements.

  19. Molecular engineering and fluorescence for the detection of toxic cations

    International Nuclear Information System (INIS)

    Souchon, V.

    2007-11-01

    This work is a part of the 'Toxicologie Nucleaire Environnementale' program which aims at studying the effects on the living of heavy metals or radionuclides involved in nuclear industry. Most particularly, it deals with the design of new fluorescent sensors for the selective detection of Pb 2+ , Cd 2+ and Cs + in biological media. Several fluorescent calixarenes possessing nitrogen atoms were synthesized and their properties as potential lead sensors were investigated. One of them could be used in experimental conditions close to biological media and new target compounds with amide functional groups were proposed. Many approaches were considered for the design of selective fluorescent sensors for cadmium. On the basis of literature results, many chelating compounds incorporating sulfur atoms were synthesized but showed no significant affinity towards cadmium. On the opposite, compounds functionalized with several pyridine-2'-yl-1,2,3-triazol fluorescent moieties linked to a β-cyclodextrin or a calix[4]arene showed good affinity for cadmium in methanol, but the selectivity was found to be insufficient. In contrast, very satisfying results in terms of both selectivity and sensitivity could be obtained with the commercial calcium sensor Rhod-5N in an aqueous medium at neutral pH. Lastly, micromolar detection limits for the selective detection of caesium were reached in an aqueous medium at neutral pH thanks to a new sulfonated fluorescent calixarene with two appended crown-ethers. An original complexation mechanism was proposed and validated by molecular modelling (DFT). (author)

  20. Detection of intaoral lesions using a fluorescence camera

    Science.gov (United States)

    Thoms, Michael

    2006-02-01

    Optical methods for the detection of carious lesions, calculus and plaque have the advantage of being minimally invasive. The use of endogeneous fluorescence markers like porphyrins could simplify the application of fluorescence techniques in the dental practice. It is known that porphyrins are produced by some of the bacterial species that are present in the oral cavity. Since porphyrins have an excitation band at about 400nm they have the potential to be used as fluorescent markers of locations in the oral cavity where the production of bacteria is out of the limits of healthy regions. Further, modern and efficient GaN-based semiconductor diodes emit light in this spectral range and thus make the implementation of fluorescence sensors with excitation at this wavelength easy. Carious lesions, calculus and plaque have been measured using a self build fluorescence camera using GaN-diodes for illumination at 405nm. Further, emission spectra under this excitation were recorded. For the latter purpose freshly extracted teeth were used. It has been found that already in the case of an initial carious lesion red porphyrin-fluorescence is emitted whereas it is absent in healthy enamel. In already brown coloured carious lesions the emission bands of porphyrin are present but the observed overall fluorescence intensity is lower, probably due to the absorption of the fluorescence by the carious defect itself. In dental calculus, dental plaque and subgingival concrements porphyrin originated luminescence was found as well. Since in these cases the emission spectra differ slightly it can be concluded that they originate from different types of porphyrins and thus also from different bacteria. These results show that this fluorescence technique can be a promising method to diagnose carious lesions, calculus and plaque.

  1. Research of the absorbance detection and fluorescence detection for multifunctional nutrition analyzer

    Science.gov (United States)

    Ni, Zhengyuan; Yan, Huimin; Ni, Xuxiang; Zhang, Xiuda

    2017-10-01

    The research of the multifunctional analyzer which integrates absorbance detection, fluorescence detection, time-resolved fluorescence detection, biochemical luminescence detection methods, can make efficient detection and analysis for a variety of human body nutrients. This article focuses on the absorbance detection and fluorescence detection system. The two systems are modular in design and controlled by embedded system, to achieve automatic measurement according to user settings. In the optical path design, the application of confocal design can improve the optical signal acquisition capability, and reduce the interference. A photon counter is used for detection, and a high performance counter module is designed to measure the output of photon counter. In the experiment, we use neutral density filters and potassium dichromate solution to test the absorbance detection system, and use fluorescein isothiocyanate FITC for fluorescence detection system performance test. The experimental results show that the absorbance detection system has a detection range of 0 4OD, and has good linearity in the detection range, while the fluorescence detection system has a high sensitivity of 1pmol/L concentration.

  2. Detection of oxidative hair treatment using fluorescence microscopy.

    Science.gov (United States)

    Witt, Silvana; Wunder, Cora; Paulke, Alexander; Verhoff, Marcel A; Schubert-Zsilavecz, Manfred; Toennes, Stefan W

    2016-08-01

    In assessing abstinence from drug or alcohol abuse, hair analysis plays an important role. Cosmetic hair treatment influences the content of deposited drugs which is not always detectable during analysis. Since oxidation of melanin leads to an increase in fluorescence, a microscopic method was developed to distinguish natural from cosmetically treated hair. For validation, natural hair samples were treated with different types of cosmetics and inspected by fluorescence microscopy. Hair samples from 20 volunteers with documented cosmetic treatment and as a proof of concept 100 hair samples from forensic cases were analyzed by this method. Apart from autofluorescence with excitation at 365 nm, no obvious fluorescence was observed in untreated hair samples. Tinting and a natural plant product had no influence on fluorescence, but dyeing procedures including oxidation led to a marked increase in fluorescence. Proof of cosmetic treatment was achieved in hair samples from the 20 volunteers. In 100 forensic cases, 13 samples were characterized as oxidatively treated, which was in accordance with the respective disclosure except for one case where treatment was not admitted. This fluorescence microscopic procedure proved to be fast, easy, and reliable to identify oxidatively treated hair samples, which must be considered especially in evaluating cases of negative drug results. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  3. Laser-induced fluorescence in the detection of esophageal carcinoma

    Science.gov (United States)

    Wang, Kenneth K.; Gutta, Kumar; Laukka, Mark A.; Densmore, John

    1995-01-01

    Laser induced fluorescence (LIF) is a technique which can perform an 'optical biopsy' of gastrointestinal mucosa. LIF was performed in resected specimens using a pulsed N2-laser coupled fiberoptically to a probe. Fluorescence was measured using a 0.2 meter spectroscope with an intensified photodiode array. Measurements were made on fresh (esophagus, and adenocarcinoma. Each tissue section was examined using an optical probe consisting of a central fiber for delivering the excitation energy and a 6 fiber bundle surrounding the central fiber for detection of the fluorescence. An excitation wavelength of 337 nm was used which generated 3-ns pulses while fluorescence intensities were acquired from 300-800 nm. Spectra were obtained from each section in a standardized fashion and background spectra subtracted. Fluorescence readings were taken from 54 normal esophageal sections and 32 sections of adenocarcinoma. A fluorescence index obtained from the tumor sections was 0.68+/- 0.01 compared with 0.51+/- 0.01 for the normal sections (pesophagus with good accuracy.

  4. Contraband Detection with Nuclear Resonance Fluorescence: Feasibility and Impact

    International Nuclear Information System (INIS)

    Pruet, J; Lange, D

    2007-01-01

    In this report they show that cargo interrogation systems developed to thwart trafficking of illicit nuclear materials could also be powerful tools in the larger fight against contraband smuggling. In particular, in addition to detecting special nuclear materials, cargo scanning systems that exploit nuclear resonance fluorescence to detect specific isotopes can be used to help find: chemical weapons; some drugs as well as some chemicals regulated under the controlled substances act; precious metals; materials regulated under export control laws; and commonly trafficked fluorocarbons

  5. Fluorescence-Based Multiplex Protein Detection Using Optically Encoded Microbeads

    Directory of Open Access Journals (Sweden)

    Dae Hong Jeong

    2012-03-01

    Full Text Available Potential utilization of proteins for early detection and diagnosis of various diseases has drawn considerable interest in the development of protein-based multiplex detection techniques. Among the various techniques for high-throughput protein screening, optically-encoded beads combined with fluorescence-based target monitoring have great advantages over the planar array-based multiplexing assays. This review discusses recent developments of analytical methods of screening protein molecules on microbead-based platforms. These include various strategies such as barcoded microbeads, molecular beacon-based techniques, and surface-enhanced Raman scattering-based techniques. Their applications for label-free protein detection are also addressed. Especially, the optically-encoded beads such as multilayer fluorescence beads and SERS-encoded beads are successful for generating a large number of coding.

  6. A novel portable fluorescence detection system for microfluidic card

    International Nuclear Information System (INIS)

    Shen, B; Xie, Y; Irawan, R

    2008-01-01

    Fluorescence based sensors are widely used in the field of biochemistry and medicine due to their high sensitivity and accuracy. But the cost and time required for each sample to be tested is high. If the diagnostic tools could be miniaturized, made simple to use and much less expensive, and readily available at the point of need such as emergency diagnosis, millions of people would be benefited from it. In this paper, we design a prototype of portable fluorescence detection system based on Fluorescence Filter Block and DAQ card which can emulate signal collection and processing functionalities. After the introduction of system structure and functional modules, we use a resolution approximation method to investigate the system performance. The evaluation shows that our prototype system has the sensitivity of 0.01 mMol/L (333.306 μg/mL) which meets most of the medical requirements.

  7. Detecting crop population growth using chlorophyll fluorescence imaging.

    Science.gov (United States)

    Wang, Heng; Qian, Xiangjie; Zhang, Lan; Xu, Sailong; Li, Haifeng; Xia, Xiaojian; Dai, Liankui; Xu, Liang; Yu, Jingquan; Liu, Xu

    2017-12-10

    For both field and greenhouse crops, it is challenging to evaluate their growth information on a large area over a long time. In this work, we developed a chlorophyll fluorescence imaging-based system for crop population growth information detection. Modular design was used to make the system provide high-intensity uniform illumination. This system can perform modulated chlorophyll fluorescence induction kinetics measurement and chlorophyll fluorescence parameter imaging over a large area of up to 45  cm×34  cm. The system can provide different lighting intensity by modulating the duty cycle of its control signal. Results of continuous monitoring of cucumbers in nitrogen deficiency show the system can reduce the judge error of crop physiological status and improve monitoring efficiency. Meanwhile, the system is promising in high throughput application scenarios.

  8. Snapshot imaging Fraunhofer line discriminator for detection of plant fluorescence

    Science.gov (United States)

    Gupta Roy, S.; Kudenov, M. W.

    2015-05-01

    Non-invasive quantification of plant health is traditionally accomplished using reflectance based metrics, such as the normalized difference vegetative index (NDVI). However, measuring plant fluorescence (both active and passive) to determine photochemistry of plants has gained importance. Due to better cost efficiency, lower power requirements, and simpler scanning synchronization, detecting passive fluorescence is preferred over active fluorescence. In this paper, we propose a high speed imaging approach for measuring passive plant fluorescence, within the hydrogen alpha Fraunhofer line at ~656 nm, using a Snapshot Imaging Fraunhofer Line Discriminator (SIFOLD). For the first time, the advantage of snapshot imaging for high throughput Fraunhofer Line Discrimination (FLD) is cultivated by our system, which is based on a multiple-image Fourier transform spectrometer and a spatial heterodyne interferometer (SHI). The SHI is a Sagnac interferometer, which is dispersion compensated using blazed diffraction gratings. We present data and techniques for calibrating the SIFOLD to any particular wavelength. This technique can be applied to quantify plant fluorescence at low cost and reduced complexity of data collection.

  9. Hemoglobin detection using carbon dots as a fluorescence probe.

    Science.gov (United States)

    Barati, Ali; Shamsipur, Mojtaba; Abdollahi, Hamid

    2015-09-15

    Herein, we have described the application of high fluorescent carbon dots (CDs) without any surface modification as a simple and fast responding fluorescence probe for sensitive and selective determination of hemoglobin (Hb) in the presence of H2O2. Although Hb itself was able to quench the fluorescence of CDs, based on the inner filter effect (IFE) of the protein that affects both excitation and emission spectra of CDs, the presence of H2O2 resulted in further improvement of the sensitivity of Hb detection. The assay is based on the reaction of Hb with H2O2 that generates reactive oxygen species including hydroxyl (OH•) and superoxide (O2(•-)) radicals under heme degradation and/or iron release from Hb and the subsequent reaction of hydroxyl radicals, as strong oxidizing agents, with CDs resulting in high fluorescence quenching. The proposed probe was used for determination of Hb in concentration range of 1-100 nM with a detection limit of 0.4 nM. The method was successfully applied to the determination of Hb in human blood samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Parallel detection experiment of fluorescence confocal microscopy using DMD.

    Science.gov (United States)

    Wang, Qingqing; Zheng, Jihong; Wang, Kangni; Gui, Kun; Guo, Hanming; Zhuang, Songlin

    2016-05-01

    Parallel detection of fluorescence confocal microscopy (PDFCM) system based on Digital Micromirror Device (DMD) is reported in this paper in order to realize simultaneous multi-channel imaging and improve detection speed. DMD is added into PDFCM system, working to take replace of the single traditional pinhole in the confocal system, which divides the laser source into multiple excitation beams. The PDFCM imaging system based on DMD is experimentally set up. The multi-channel image of fluorescence signal of potato cells sample is detected by parallel lateral scanning in order to verify the feasibility of introducing the DMD into fluorescence confocal microscope. In addition, for the purpose of characterizing the microscope, the depth response curve is also acquired. The experimental result shows that in contrast to conventional microscopy, the DMD-based PDFCM system has higher axial resolution and faster detection speed, which may bring some potential benefits in the biology and medicine analysis. SCANNING 38:234-239, 2016. © 2015 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

  11. Pollution detection using the spectral fluorescent signatures (SFS technique

    Directory of Open Access Journals (Sweden)

    Mª Del Carmen Martín

    2014-06-01

    Full Text Available This work has been developed in the Applied Physics Department at the University of Vigo within the line of research based on the treatment of the degraded water by pollutants through the use of microalgae, reducing the emissions of greenhouse gases through the absorption of CO2 in the process and the reuse of biomass as biofuel. Remote sensing techniques have contributed to a great extent to the development of oil pollution monitoring systems. However, the available detection methods, mainly designed for spaceborne and airborne long distance inspection, are too expensive and complex to be used in an operational way by relatively unskilled personnel. In the framework of DEOSOM project (European AMPERA project, an innovative water monitoring method was proposed, in two steps: early oil spill detection using a portable shipborne laser-induced fluorescence LIDAR (LIF/LIDAR, and analysis of suspicious water samples in laboratory using the Spectral Fluorescent Signature (SFS technique. This work is focused on the second technique. This system aims to optimize the production of microalgae for biofuel and contaminant cleaning applications and was developed and tested in photo-bioreactors in the University of Vigo within the EnerBioAlgae project (SUDOE. In this project, the SFS technique was used as a diagnostic tool employing the fluorescence analyzer INSTANT-SCREENER M53UVC. The Spectral Fluorescence Signature technique (SFS is based on compounds fluorescence properties. The fluorescence intensity of a sample is measured at different excitation and emission wavelengths to produce a 3-dimensional fluorescence matrix, which can also be presented as a 2-dimensional color image where the color shows the intensity of the fluorescence. These matrices offer qualitative and quantitative information, since they can be useful for the identification of different substances from their characteristic excitation and emission spectra of fluorescence. They also

  12. A nanocluster-based fluorescent sensor for sensitive hemoglobin detection.

    Science.gov (United States)

    Yang, Dongqin; Meng, Huijie; Tu, Yifeng; Yan, Jilin

    2017-08-01

    In this report, a fluorescence sensor for sensitive detection of hemoglobin was developed. Gold nanoclusters were first synthesized with bovine serum albumin. It was found that both hydrogen peroxide and hemoglobin could weakly quench the fluorescence from the gold nanoclusters, but when these two were applied onto the nanolcusters simultaneously, a much improved quenching was resulted. This enhancing effect was proved to come from the catalytic generation of hydroxyl radical by hemoglobin. Under an optimized condition, the quenching linearly related to the concentration of hemoglobin in the range of 1-250nM, and a limit of detection as low as 0.36nM could be obtained. This provided a sensitive means for the quantification of Hb. The sensor was then successfully applied for blood analyses with simple sample pretreatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Fluorescence diffuse tomography for tumor detection and monitoring

    Science.gov (United States)

    Balalaeva, Irina V.; Orlova, Anna G.; Shirmanova, Marina V.; Kibraeva, Elena A.; Zagainova, Elena V.; Turchin, Ilya V.

    2007-05-01

    Strong light scattering and absorption limit visualization of the internal structure of biological tissue. Only special tools for turbid media imaging, such as optical diffuse tomography, enable noninvasive investigation of the internal biological tissues, including visualization and intravital monitoring of deep tumors. In this work the preliminary results of fluorescence diffuse tomography (FDT) of small animals are presented. Using of exogenous fluorophores, targeted specifically at tumor cells, and fluorescent proteins expressed endogenously can significantly increase the contrast of obtained images. Fluorescent compounds of different nature, such as sulphonated aluminium phthalocyanine (Photosens), red fluorescing proteins and CdTe/CdSe-core/shell nanocrystals (quantum dots) were applied. The animal was scanned in the transilluminative configuration by low-frequency modulated light (1 kHz) from Nd:YAG laser with second harmonic generation at the wavelength of 532 nm or semiconductor laser at the wavelength of 655 nm. Photosens was injected intravenously into linear mice with metastazing Lewis lung carcinoma in dose 4 mg/kg. Quantum dots (5x10 -11 M) or protein DsRed2 (1-5x10 -6 M) in glass capsules (inner diameter 2-3 mm) were placed inside the esophagus of 7-day-old hairless rats (18-20 g) to simulate marked tumors. Cells of HEK-293 Phoenix line, transitory transfected with Turbo-RFP protein gene, were injected hypodermically to immunodeficient mice. This work demonstrates potential capabilities of FDT method for detection and monitoring of deep fluorescent-labeled tumors in animal models. Strong advantages of fluorescent proteins and quantum dots over the traditional photosensitizer for FDT imaging are shown.

  14. Multicolor fluorescent biosensor for multiplexed detection of DNA.

    Science.gov (United States)

    Hu, Rong; Liu, Tao; Zhang, Xiao-Bing; Huan, Shuang-Yan; Wu, Cuichen; Fu, Ting; Tan, Weihong

    2014-05-20

    Development of efficient methods for highly sensitive and rapid screening of specific oligonucleotide sequences is essential to the early diagnosis of serious diseases. In this work, an aggregated cationic perylene diimide (PDI) derivative was found to efficiently quench the fluorescence emission of a variety of anionic oligonucleotide-labeled fluorophores that emit at wavelengths from the visible to NIR region. This broad-spectrum quencher was then adopted to develop a multicolor biosensor via a label-free approach for multiplexed fluorescent detection of DNA. The aggregated perylene derivative exhibits a very high quenching efficiency on all ssDNA-labeled dyes associated with biosensor detection, having efficiency values of 98.3 ± 0.9%, 97 ± 1.1%, and 98.2 ± 0.6% for FAM, TAMRA, and Cy5, respectively. An exonuclease-assisted autocatalytic target recycling amplification was also integrated into the sensing system. High quenching efficiency combined with autocatalytic target recycling amplification afforded the biosensor with high sensitivity toward target DNA, resulting in a detection limit of 20 pM, which is about 50-fold lower than that of traditional unamplified homogeneous fluorescent assay methods. The quencher did not interfere with the catalytic activity of nuclease, and the biosensor could be manipulated in either preaddition or postaddition manner with similar sensitivity. Moreover, the proposed sensing system allows for simultaneous and multicolor analysis of several oligonucleotides in homogeneous solution, demonstrating its potential application in the rapid screening of multiple biotargets.

  15. In Vivo Dual Fluorescence Imaging to Detect Joint Destruction.

    Science.gov (United States)

    Cho, Hongsik; Bhatti, Fazal-Ur-Rehman; Lee, Sangmin; Brand, David D; Yi, Ae-Kyung; Hasty, Karen A

    2016-10-01

    Diagnosis of cartilage damage in early stages of arthritis is vital to impede the progression of disease. In this regard, considerable progress has been made in near-infrared fluorescence (NIRF) optical imaging technique. Arthritis can develop due to various mechanisms but one of the main contributors is the production of matrix metalloproteinases (MMPs), enzymes that can degrade components of the extracellular matrix. Especially, MMP-1 and MMP-13 have main roles in rheumatoid arthritis and osteoarthritis because they enhance collagen degradation in the process of arthritis. We present here a novel NIRF imaging strategy that can be used to determine the activity of MMPs and cartilage damage simultaneously by detection of exposed type II collagen in cartilage tissue. In this study, retro-orbital injection of mixed fluorescent dyes, MMPSense 750 FAST (MMP750) dye and Alexa Fluor 680 conjugated monoclonal mouse antibody immune-reactive to type II collagen, was administered in the arthritic mice. Both dyes were detected with different intensity according to degree of joint destruction in the animal. Thus, our dual fluorescence imaging method can be used to detect cartilage damage as well as MMP activity simultaneously in early stage arthritis. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  16. Novel DNA sequence detection method based on fluorescence energy transfer

    International Nuclear Information System (INIS)

    Kobayashi, S.; Tamiya, E.; Karube, I.

    1987-01-01

    Recently the detection of specific DNA sequence, DNA analysis, has been becoming more important for diagnosis of viral genomes causing infections disease and human sequences related to inherited disorders. These methods typically involve electrophoresis, the immobilization of DNA on a solid support, hybridization to a complementary probe, the detection using labeled with /sup 32/P or nonisotopically with a biotin-avidin-enzyme system, and so on. These techniques are highly effective, but they are very time-consuming and expensive. A principle of fluorescene energy transfer is that the light energy from an excited donor (fluorophore) is transferred to an acceptor (fluorophore), if the acceptor exists in the vicinity of the donor and the excitation spectrum of donor overlaps the emission spectrum of acceptor. In this study, the fluorescence energy transfer was applied to the detection of specific DNA sequence using the hybridization method. The analyte, single-stranded DNA labeled with the donor fluorophore is hybridized to a probe DNA labeled with the acceptor. Because of the complementary DNA duplex formation, two fluorophores became to be closed to each other, and the fluorescence energy transfer was occurred

  17. Selective Detection of Neurotransmitters by Fluorescence and Chemiluminescence Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ziqiang Wang; Edward S. Yeung

    2001-08-06

    In recent years, luminescence imaging has been widely employed in neurochemical analysis. It has a number of advantages for the study of neuronal and other biological cells: (1) a particular molecular species or cellular constituent can be selectively visualized in the presence of a large excess of other species in a heterogeneous environment; (2) low concentration detection limits can be achieved because of the inherent sensitivity associated with fluorescence and chemiluminescence; (3) low excitation intensities can be used so that long-term observation can be realized while the viability of the specimen is preserved; and (4) excellent spatial resolution can be obtained with the light microscope so subcellular compartments can be identified. With good sensitivity, temporal and spatial resolution, the flux of ions and molecules and the distribution and dynamics of intracellular species can be measured in real time with specific luminescence probes, substrates, or with native fluorescence. A noninvasive detection scheme based on glutamate dehydrogenase (GDH) enzymatic assay combined with microscopy was developed to measure the glutamate release in cultured cells from the central nervous system (CNS). The enzyme reaction is very specific and sensitive. The detection limit with CCD imaging is down to {micro}M levels of glutamate with reasonable response time. They also found that chemiluminescence associated with the ATP-dependent reaction between luciferase and luciferin can be used to image ATP at levels down to 10 nM in the millisecond time scale. Similar imaging experiments should be feasible in a broad spectrum of biological systems.

  18. Community detection for fluorescent lifetime microscopy image segmentation

    Science.gov (United States)

    Hu, Dandan; Sarder, Pinaki; Ronhovde, Peter; Achilefu, Samuel; Nussinov, Zohar

    2014-03-01

    Multiresolution community detection (CD) method has been suggested in a recent work as an efficient method for performing unsupervised segmentation of fluorescence lifetime (FLT) images of live cell images containing fluorescent molecular probes.1 In the current paper, we further explore this method in FLT images of ex vivo tissue slices. The image processing problem is framed as identifying clusters with respective average FLTs against a background or "solvent" in FLT imaging microscopy (FLIM) images derived using NIR fluorescent dyes. We have identified significant multiresolution structures using replica correlations in these images, where such correlations are manifested by information theoretic overlaps of the independent solutions ("replicas") attained using the multiresolution CD method from different starting points. In this paper, our method is found to be more efficient than a current state-of-the-art image segmentation method based on mixture of Gaussian distributions. It offers more than 1:25 times diversity based on Shannon index than the latter method, in selecting clusters with distinct average FLTs in NIR FLIM images.

  19. Chemical point detection using differential fluorescence from molecularly imprinted polymers

    Science.gov (United States)

    Pestov, Dmitry; Anderson, John E.; Nelson, Jean; Tepper, Gary C.

    2004-12-01

    Fluorescence represents one of the most attractive approaches for chemical sensing due to the abundant light produced by most fluorophores, resulting in excellent detection sensitivity. However, the broad and overlapping emission spectra of target and background species have made it difficult to perform species identification in a field instrument because of the need to perform spectral decomposition and analysis. This paper describes a new chemical sensing strategy based on differential fluorescence measurements from molecularly imprinted polymers, which eliminates the need to perform any spectral analysis. Species identification is accomplished by measuring the differential light output from a pair of polymers-one imprinted to a target species and the other identical, but not imprinted. The imprinted polymer selectively concentrates the target molecule and controls the energy (wavelength) of the emitted fluorescence signal and the differential output eliminates common mode signals associated with non-specific background interference. Because no spectral analysis is required, the sensors can be made extremely small and require very little power. Preliminary performance parameters from a prototype sensor are presented and discussed.

  20. Single photon counting fluorescence lifetime detection of pericellular oxygen concentrations.

    Science.gov (United States)

    Hosny, Neveen A; Lee, David A; Knight, Martin M

    2012-01-01

    Fluorescence lifetime imaging microscopy offers a non-invasive method for quantifying local oxygen concentrations. However, existing methods are either invasive, require custom-made systems, or show limited spatial resolution. Therefore, these methods are unsuitable for investigation of pericellular oxygen concentrations. This study describes an adaptation of commercially available equipment which has been optimized for quantitative extracellular oxygen detection with high lifetime accuracy and spatial resolution while avoiding systematic photon pile-up. The oxygen sensitive fluorescent dye, tris(2,2'-bipyridyl)ruthenium(II) chloride hexahydrate [Ru(bipy)(3)](2+), was excited using a two-photon excitation laser. Lifetime was measured using a Becker & Hickl time-correlated single photon counting, which will be referred to as a TCSPC card. [Ru(bipy)(3)](2+) characterization studies quantified the influences of temperature, pH, cellular culture media and oxygen on the fluorescence lifetime measurements. This provided a precisely calibrated and accurate system for quantification of pericellular oxygen concentration based on measured lifetimes. Using this technique, quantification of oxygen concentrations around isolated viable chondrocytes, seeded in three-dimensional agarose gel, revealed a subpopulation of cells that exhibited significant spatial oxygen gradients such that oxygen concentration reduced with increasing proximity to the cell. This technique provides a powerful tool for quantifying spatial oxygen gradients within three-dimensional cellular models.

  1. Microbial biofilm detection on food contact surfaces by macro-scale fluorescence imaging

    Science.gov (United States)

    Hyperspectral fluorescence imaging methods were utilized to evaluate the potential of multispectral fluorescence methods for detection of pathogenic biofilm formations on four types of food contact surface materials: stainless steel, high density polyethylene (HDPE) commonly used for cutting boards,...

  2. Protein- protein interaction detection system using fluorescent protein microdomains

    Science.gov (United States)

    Waldo, Geoffrey S.; Cabantous, Stephanie

    2010-02-23

    The invention provides a protein labeling and interaction detection system based on engineered fragments of fluorescent and chromophoric proteins that require fused interacting polypeptides to drive the association of the fragments, and further are soluble and stable, and do not change the solubility of polypeptides to which they are fused. In one embodiment, a test protein X is fused to a sixteen amino acid fragment of GFP (.beta.-strand 10, amino acids 198-214), engineered to not perturb fusion protein solubility. A second test protein Y is fused to a sixteen amino acid fragment of GFP (.beta.-strand 11, amino acids 215-230), engineered to not perturb fusion protein solubility. When X and Y interact, they bring the GFP strands into proximity, and are detected by complementation with a third GFP fragment consisting of GFP amino acids 1-198 (strands 1-9). When GFP strands 10 and 11 are held together by interaction of protein X and Y, they spontaneous association with GFP strands 1-9, resulting in structural complementation, folding, and concomitant GFP fluorescence.

  3. Integrated Micro-Optical Fluorescence Detection System for Microfluidic Electrochromatography

    International Nuclear Information System (INIS)

    ALLERMAN, ANDREW A.; ARNOLD, DON W.; ASBILL, RANDOLPH E.; BAILEY, CHRISTOPHER G.; CARTER, TONY RAY; KEMME, SHANALYN A.; MATZKE, CAROLYN M.; SAMORA, SALLY; SWEATT, WILLIAM C.; WARREN, MIAL E.; WENDT, JOEL R.

    1999-01-01

    The authors describe the design and microfabrication of an extremely compact optical system as a key element in an integrated capillary-channel electrochromatograph with laser induced fluorescence detection. The optical design uses substrate-mode propagation within the fused silica substrate. The optical system includes a vertical cavity surface-emitting laser (VCSEL) array, two high performance microlenses and a commercial photodetector. The microlenses are multilevel diffractive optics patterned by electron beam lithography and etched by reactive ion etching in fused silica. Two generations of optical subsystems are described. The first generation design is integrated directly onto the capillary channel-containing substrate with a 6 mm separation between the VCSEL and photodetector. The second generation design separates the optical system onto its own module and the source to detector length is further compressed to 3.5 mm. The systems are designed for indirect fluorescence detection using infrared dyes. The first generation design has been tested with a 750 nm VCSEL exciting a 10(sup -4) M solution of CY-7 dye. The observed signal-to-noise ratio of better than 100:1 demonstrates that the background signal from scattered pump light is low despite the compact size of the optical system and meets the system sensitivity requirements

  4. Fluorescence spectroscopy for throat cancer detection using human saliva

    Science.gov (United States)

    Kumar, Pavan; Singh, Ashutosh; Zaffar, Mohammad; Pradhan, Asima

    2018-02-01

    Throat precancer detection using fluorescence from human saliva is reported here. It may be noted that accessing the throat for investigation is cumbersome and use of saliva as a diagnostic medium may ease the process. The study has been conducted on three groups of patients: oral squamous cell carcinoma (OSCC), dysplasia, and normal (control). An in-house developed compact set-up has been used for fluorescence measurements. The compact system consist of a 375 nm laser diode, collimating lens, long pass filter, fibers, and cuvette holder. Major and minor bands of flavin adenine dinucleotide (FAD) and porphyrin are observed in the spectra. A receiver operating characteristic (ROC) analysis has been used to evaluate the diagnostic performance. Area under the spectra has been chosen for discrimination among the groups and is able to differentiate OSCC to normal, dysplasia to normal, and OSCC to dysplasia with sensitivities 100% (48/48), 92% (32/35), 77% (37/48), and specificities 96% (50/52), 96% (50/52), 89% (31/35) with the accuracy of 98%, 94% and 82% respectively. Sensitivity and specificity, when differentiating OSCC to normal and dysplasia to normal, are significantly large, which indicates that human saliva may be an excellent diagnostic medium for early detection of throat cancer.

  5. Native Fluorescence Detection Methods, Devices, and Systems for Organic Compounds

    Science.gov (United States)

    Hug, William F. (Inventor); Bhartia, Rohit (Inventor); Reid, Ray D. (Inventor); Lane, Arthur L. (Inventor)

    2018-01-01

    Naphthalene, benzene, toluene, xylene, and other volatile organic compounds VOCs have been identified as serious health hazards. Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined.

  6. Colorectal cancer detection by hyperspectral imaging using fluorescence excitation scanning

    Science.gov (United States)

    Leavesley, Silas J.; Deal, Joshua; Hill, Shante; Martin, Will A.; Lall, Malvika; Lopez, Carmen; Rider, Paul F.; Rich, Thomas C.; Boudreaux, Carole W.

    2018-02-01

    Hyperspectral imaging technologies have shown great promise for biomedical applications. These techniques have been especially useful for detection of molecular events and characterization of cell, tissue, and biomaterial composition. Unfortunately, hyperspectral imaging technologies have been slow to translate to clinical devices - likely due to increased cost and complexity of the technology as well as long acquisition times often required to sample a spectral image. We have demonstrated that hyperspectral imaging approaches which scan the fluorescence excitation spectrum can provide increased signal strength and faster imaging, compared to traditional emission-scanning approaches. We have also demonstrated that excitation-scanning approaches may be able to detect spectral differences between colonic adenomas and adenocarcinomas and normal mucosa in flash-frozen tissues. Here, we report feasibility results from using excitation-scanning hyperspectral imaging to screen pairs of fresh tumoral and nontumoral colorectal tissues. Tissues were imaged using a novel hyperspectral imaging fluorescence excitation scanning microscope, sampling a wavelength range of 360-550 nm, at 5 nm increments. Image data were corrected to achieve a NIST-traceable flat spectral response. Image data were then analyzed using a range of supervised and unsupervised classification approaches within ENVI software (Harris Geospatial Solutions). Supervised classification resulted in >99% accuracy for single-patient image data, but only 64% accuracy for multi-patient classification (n=9 to date), with the drop in accuracy due to increased false-positive detection rates. Hence, initial data indicate that this approach may be a viable detection approach, but that larger patient sample sizes need to be evaluated and the effects of inter-patient variability studied.

  7. Detection of dengue group viruses by fluorescence in situ hybridization

    Directory of Open Access Journals (Sweden)

    Raquin Vincent

    2012-10-01

    Full Text Available Abstract Background Dengue fever (DF and dengue hemorrhagic fever (DHF represent a global challenge in public health. It is estimated that 50 to 100 million infections occur each year causing approximately 20,000 deaths that are usually linked to severe cases like DHF and dengue shock syndrome. The causative agent of DF is dengue virus (genus Flavivirus that comprises four distinct serotypes (DENV-1 to DENV-4. Fluorescence in situ hybridization (FISH has been used successfully to detect pathogenic agents, but has not been implemented in detecting DENV. To improve our understanding of DENV infection and dissemination in host tissues, we designed specific probes to detect DENV in FISH assays. Methods Oligonucleotide probes were designed to hybridize with RNA from the broadest range of DENV isolates belonging to the four serotypes, but not to the closest Flavivirus genomes. Three probes that fit the criteria defined for FISH experiments were selected, targeting both coding and non-coding regions of the DENV genome. These probes were tested in FISH assays against the dengue vector Aedes albopictus (Diptera: Culicidae. The FISH experiments were led in vitro using the C6/36 cell line, and in vivo against dissected salivary glands, with epifluorescence and confocal microscopy. Results The three 60-nt oligonucleotides probes DENV-Probe A, B and C cover a broad range of DENV isolates from the four serotypes. When the three probes were used together, specific fluorescent signals were observed in C6/36 infected with each DENV serotypes. No signal was detected in either cells infected with close Flavivirus members West Nile virus or yellow fever virus. The same protocol was used on salivary glands of Ae. albopictus fed with a DENV-2 infectious blood-meal which showed positive signals in the lateral lobes of infected samples, with no significant signal in uninfected mosquitoes. Conclusion Based on the FISH technique, we propose a way to design and use

  8. [Fluorescence Resonance Energy Transfer Detection of Cobalt Ions by Silver Triangular Nanoplates and Rhodamine 6G].

    Science.gov (United States)

    Zhang, Xiu-qing; Peng, Jun; Ling, Jian; Liu, Chao-juan; Cao, Qiu-e; Ding, Zhong-tao

    2015-04-01

    In the present paper, the authors studied fluorescence resonance energy transfer (FRET) phenomenon between silver triangular nanoplates and bovine serum albumin (BSA)/Rhodamine 6G fluorescence complex, and established a fluorescence method for the detection of cobalt ions. We found that when increasing the silver triangular nanoplates added to certain concentrations of fluorescent bovine serum albumin (BSA)/Rhodamine 6G complex, the fluorescence of Rhodamine 6G would be quenched up to 80% due to the FRET between the quencher and donor. However, in the presence of cobalt ions, the disassociation of the fluorescent complex from silver triangular nanoplates occurred and the fluorescence of the Rhodamine 6G recovered. The recovery of fluorescence intensity rate (I/I0) has a good relationship with the cobalt ion concentration (cCO2+) added. Thus, the authors developed a fluorescence method for the detection of cobalt ions based on the FRET of silver triangular nanoplates and Rhodamine 6G.

  9. Microcystin Detection Characteristics of Fluorescence Immunochromatography and High Performance Liquid Chromatography

    International Nuclear Information System (INIS)

    Pyo, Dong Jin; Park, Geun Young; Choi, Jong Chon; Oh, Chang Suk

    2005-01-01

    Different detection characteristics of fluorescence immunochromatography method and high performance liquid chromatography (HPLC) method for the analysis of cyanobacterial toxins were studied. In particular, low and high limits of detection, detection time and reproducibility and detectable microcystin species were compared when fluorescence immunochromatography method and high performance liquid chromatography method were applied for the detection of microcystin (MC), a cyclic peptide toxin of the freshwater cyanobacterium Microcystis aeruginosa. A Fluorescence immunochromatography assay system has the unique advantages of short detection time and low detection limit, and high performance liquid chromatography detection method has the strong advantage of individual quantifications of several species of microcystins

  10. Self-organized fluorescent nanosensors for ratiometric Pb2+ detection.

    Science.gov (United States)

    Arduini, Maria; Mancin, Fabrizio; Tecilla, Paolo; Tonellato, Umberto

    2007-07-31

    Silica nanoparticles (60 nm diameter) doped with fluorescent dyes and functionalized on the surface with thiol groups have been proved to be efficient fluorescent chemosensors for Pb2+ ions. The particles can detect a 1 microM metal ion concentration with a good selectivity, suffering only interference from Cu2+ ions. Analyte binding sites are provided by the simple grafting of the thiol groups on the nanoparticles. Once bound to the particles surface, the Pb2+ ions quench the emission of the reporting dyes embedded. Sensor performances can be improved by taking advantage of the ease of production of multishell silica particles. On one hand, signaling units can be concentrated in the external shells, allowing a closer interaction with the surface-bound analyte. On the other, a second dye can be buried in the particle core, far enough from the surface to be unaffected by the Pb2+ ions, thus producing a reference signal. In this way, a ratiometric system is easily prepared by simple self-organization of the particle components.

  11. Detection of vitellogenin incorporation into zebrafish oocytes by FITC fluorescence

    Directory of Open Access Journals (Sweden)

    Yokoi Hayato

    2011-04-01

    Full Text Available Abstract Background Large volumes of lymph can be collected from the eye-sacs of bubble-eye goldfish. We attempted to induce vitellogenin (Vtg in the eye-sac lymph of bubble-eye goldfish and develop a method for visualizing Vtg incorporation by zebrafish oocytes using FITC-labeling. Methods Estrogen efficiently induced Vtg in the eye-sac lymph of goldfish. After FITC-labeled Vtg was prepared, it was injected into mature female zebrafish. Results Incorporation of FITC-labeled Vtg by zebrafish oocytes was detected in in vivo and in vitro experiments. The embryos obtained from zebrafish females injected with FITC-labeled Vtg emitted FITC fluorescence from the yolk sac and developed normally. Conclusion This method for achieving Vtg incorporation by zebrafish oocytes could be useful in experiments related to the development and endocrinology of zebrafish oocytes.

  12. An eco-friendly molecularly imprinted fluorescence composite material based on carbon dots for fluorescent detection of 4-nitrophenol

    International Nuclear Information System (INIS)

    Hao, Tongfan; Wei, Xiao; Nie, Yijing; Zhou, Zhiping; Xu, Yeqing; Yan, Yongsheng

    2016-01-01

    We on report an eco-friendly molecularly imprinted material based on carbon dots (C-dots) via a facile and efficient sol–gel polymerization for selective fluorescence detection of 4-nitrophenol (4-NP). The amino-modified C-dots were firstly synthesized by a hydrothermal process using citric acid as the carbon source and poly(ethyleneimine) as the surface modifier, and then after a sol–gel molecular imprinting process, the molecularly imprinted fluorescence material was obtained. The material (MIP-C-dots) showed strong fluorescence from C-dots and high selectivity due to the presence of a molecular imprint. After the detection conditions were optimized, the relative fluorescence intensity (F_0/F) of MIP-C-dots presented a good linearity with 4-NP concentrations in the linear range of 0.2 − 50 μmol L"-"1 with a detection limit (3σ/k) of 0.06 μmol L"-"1. In addition, the correlation coefficient was 0.9978 and the imprinting factor was 2.76. The method was applicable to the determination of trace 4-NP in Yangtze River water samples and good recoveries from 92.6–107.3 % were obtained. The present study provides a general strategy to fabricate materials based on C-dots with good fluorescence property for selective fluorescence detection of organic pollutants. (author)

  13. Early Detection of Breast Cancer by Fluorescence Molecular Tomography

    National Research Council Canada - National Science Library

    Ntziachristos, Vasilis

    2007-01-01

    .... We have successfully completed all goals and achieved the three major aims of the proposal, i.e. i) the development of appropriate fluorescence imaging methods for highly reliable and quantitative fluorescence imaging ii...

  14. Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

    Science.gov (United States)

    Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

    1993-01-01

    A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

  15. Mechanical Damage Detection of Indonesia Local Citrus Based on Fluorescence Imaging

    Science.gov (United States)

    Siregar, T. H.; Ahmad, U.; Sutrisno; Maddu, A.

    2018-05-01

    Citrus experienced physical damage in peel will produce essential oils that contain polymethoxylated flavone. Polymethoxylated flavone is fluorescence substance; thus can be detected by fluorescence imaging. This study aims to study the fluorescence spectra characteristic and to determine the damage region in citrus peel based on fluorescence image. Pulung citrus from Batu district, East Java, as a famous citrus production area in Indonesia, was used in the experiment. It was observed that the image processing could detect the mechanical damage region. Fluorescence imaging can be used to classify the citrus into two categories, sound and defect citruses.

  16. Protein assisted fluorescence enhancement of a dansyl containing fluorescent reagent: detection of Hg+ ion in aqueous medium.

    Science.gov (United States)

    Srivastava, Priyanka; Shahid, Mohammad; Misra, Arvind

    2011-07-21

    Intramolecular charge transfer (ICT) based fluorescent reagents containing a dansyl fluorophore have been synthesized and characterized. The reagent 1 and its complex, 1+Hg(2+) in sodium acetate buffer (pH 6.7) revealed considerable fluorescence enhancement (switched-on) in the presence of bovine serum albumin (BSA) with 10 ppb detection sensitivity. (1)H NMR spectral analysis suggests complexation between 1 and Hg(2+) ion involving the N,N-dimethylamino and carboxylic functions.

  17. Fluorescence-Based Bioassays for the Detection and Evaluation of Food Materials

    OpenAIRE

    Nishi, Kentaro; Isobe, Shin-Ichiro; Zhu, Yun; Kiyama, Ryoiti

    2015-01-01

    We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based mi...

  18. Fluorescence detection of natural RNA using rationally designed "clickable" oligonucleotide probes

    DEFF Research Database (Denmark)

    Okholm, Anders; Kjems, Jørgen; Astakhova, Kira

    2014-01-01

    Herein a reliable approach to the design of effective fluorescent probes for RNA detection is described. The fluorescence signalling of hybridization by internally positioned polyaromatic hydrocarbons and rhodamine dyes was achieved with a low fluorescence background signal, high fluorescence qua...... quantum yields at ambient and elevated temperature, high selectivity and signal specificity of the probes when binding to miR-7 and circRNA targets....

  19. Ultrasensitive fluorescence immunoassay for detection of ochratoxin A using catalase-mediated fluorescence quenching of CdTe QDs

    Science.gov (United States)

    Huang, Xiaolin; Zhan, Shengnan; Xu, Hengyi; Meng, Xianwei; Xiong, Yonghua; Chen, Xiaoyuan

    2016-04-01

    Herein, for the first time we report an improved competitive fluorescent enzyme linked immunosorbent assay (ELISA) for the ultrasensitive detection of ochratoxin A (OTA) by using hydrogen peroxide (H2O2)-induced fluorescence quenching of mercaptopropionic acid-modified CdTe quantum dots (QDs). In this immunoassay, catalase (CAT) was labeled with OTA as a competitive antigen to connect the fluorescence signals of the QDs with the concentration of the target. Through the combinatorial use of H2O2-induced fluorescence quenching of CdTe QDs as a fluorescence signal output and the ultrahigh catalytic activity of CAT to H2O2, our proposed method could be used to perform a dynamic linear detection of OTA ranging from 0.05 pg mL-1 to 10 pg mL-1. The half maximal inhibitory concentration was 0.53 pg mL-1 and the limit of detection was 0.05 pg mL-1. These values were approximately 283- and 300-folds lower than those of horseradish peroxidase (HRP)-based conventional ELISA, respectively. The reported method is accurate, highly reproducible, and specific against other mycotoxins in agricultural products as well. In summary, the developed fluorescence immunoassay based on H2O2-induced fluorescence quenching of CdTe QDs can be used for the rapid and highly sensitive detection of mycotoxins or haptens in food safety monitoring.Herein, for the first time we report an improved competitive fluorescent enzyme linked immunosorbent assay (ELISA) for the ultrasensitive detection of ochratoxin A (OTA) by using hydrogen peroxide (H2O2)-induced fluorescence quenching of mercaptopropionic acid-modified CdTe quantum dots (QDs). In this immunoassay, catalase (CAT) was labeled with OTA as a competitive antigen to connect the fluorescence signals of the QDs with the concentration of the target. Through the combinatorial use of H2O2-induced fluorescence quenching of CdTe QDs as a fluorescence signal output and the ultrahigh catalytic activity of CAT to H2O2, our proposed method could be used to

  20. Fluorescent Receptor Binding Assay for Detecting Ciguatoxins in Fish.

    Science.gov (United States)

    Hardison, D Ransom; Holland, William C; McCall, Jennifer R; Bourdelais, Andrea J; Baden, Daniel G; Darius, H Taiana; Chinain, Mireille; Tester, Patricia A; Shea, Damian; Quintana, Harold A Flores; Morris, James A; Litaker, R Wayne

    2016-01-01

    Ciguatera fish poisoning is an illness suffered by > 50,000 people yearly after consumption of fish containing ciguatoxins (CTXs). One of the current methodologies to detect ciguatoxins in fish is a radiolabeled receptor binding assay (RBA(R)). However, the license requirements and regulations pertaining to radioisotope utilization can limit the applicability of the RBA(R) in certain labs. A fluorescence based receptor binding assay (RBA(F)) was developed to provide an alternative method of screening fish samples for CTXs in facilities not certified to use radioisotopes. The new assay is based on competition binding between CTXs and fluorescently labeled brevetoxin-2 (BODIPY®-PbTx-2) for voltage-gated sodium channel receptors at site 5 instead of a radiolabeled brevetoxin. Responses were linear in fish tissues spiked from 0.1 to 1.0 ppb with Pacific ciguatoxin-3C (P-CTX-3C) with a detection limit of 0.075 ppb. Carribean ciguatoxins were confirmed in Caribbean fish by LC-MS/MS analysis of the regional biomarker (C-CTX-1). Fish (N = 61) of six different species were screened using the RBA(F). Results for corresponding samples analyzed using the neuroblastoma cell-based assay (CBA-N2a) correlated well (R2 = 0.71) with those of the RBA(F), given the low levels of CTX present in positive fish. Data analyses also showed the resulting toxicity levels of P-CTX-3C equivalents determined by CBA-N2a were consistently lower than the RBA(F) affinities expressed as % binding equivalents, indicating that a given amount of toxin bound to the site 5 receptors translates into corresponding lower cytotoxicity. Consequently, the RBA(F), which takes approximately two hours to perform, provides a generous estimate relative to the widely used CBA-N2a which requires 2.5 days to complete. Other RBA(F) advantages include the long-term (> 5 years) stability of the BODIPY®-PbTx-2 and having similar results as the commonly used RBA(R). The RBA(F) is cost-effective, allows high sample

  1. Fluorescent Receptor Binding Assay for Detecting Ciguatoxins in Fish.

    Directory of Open Access Journals (Sweden)

    D Ransom Hardison

    Full Text Available Ciguatera fish poisoning is an illness suffered by > 50,000 people yearly after consumption of fish containing ciguatoxins (CTXs. One of the current methodologies to detect ciguatoxins in fish is a radiolabeled receptor binding assay (RBA(R. However, the license requirements and regulations pertaining to radioisotope utilization can limit the applicability of the RBA(R in certain labs. A fluorescence based receptor binding assay (RBA(F was developed to provide an alternative method of screening fish samples for CTXs in facilities not certified to use radioisotopes. The new assay is based on competition binding between CTXs and fluorescently labeled brevetoxin-2 (BODIPY®-PbTx-2 for voltage-gated sodium channel receptors at site 5 instead of a radiolabeled brevetoxin. Responses were linear in fish tissues spiked from 0.1 to 1.0 ppb with Pacific ciguatoxin-3C (P-CTX-3C with a detection limit of 0.075 ppb. Carribean ciguatoxins were confirmed in Caribbean fish by LC-MS/MS analysis of the regional biomarker (C-CTX-1. Fish (N = 61 of six different species were screened using the RBA(F. Results for corresponding samples analyzed using the neuroblastoma cell-based assay (CBA-N2a correlated well (R2 = 0.71 with those of the RBA(F, given the low levels of CTX present in positive fish. Data analyses also showed the resulting toxicity levels of P-CTX-3C equivalents determined by CBA-N2a were consistently lower than the RBA(F affinities expressed as % binding equivalents, indicating that a given amount of toxin bound to the site 5 receptors translates into corresponding lower cytotoxicity. Consequently, the RBA(F, which takes approximately two hours to perform, provides a generous estimate relative to the widely used CBA-N2a which requires 2.5 days to complete. Other RBA(F advantages include the long-term (> 5 years stability of the BODIPY®-PbTx-2 and having similar results as the commonly used RBA(R. The RBA(F is cost-effective, allows high sample

  2. A low-cost 2D fluorescence detection system for mm sized beads on-chip

    NARCIS (Netherlands)

    Segerink, Loes Irene; Koster, Maarten J.; Sprenkels, A.J.; van den Berg, Albert

    2012-01-01

    In this paper we describe a compact fluorescence detection system for on-chip analysis of beads, comprising a low-cost optical HD-DVD pickup. The complete system consists of a fluorescence detection unit, a control unit and a microfluidic chip containing microchannels and optical markers. With these

  3. Sensitive detection of nucleic acids by PNA hybridization directed co-localization of fluorescent beads

    DEFF Research Database (Denmark)

    Shiraishi, Takehiko; Deborggraeve, Stijn; Büscher, Philippe

    2011-01-01

    )avidin-coated fluorescent beads, differing in size and color [green beads (1 µm) and red beads (5.9 µm)], thereby allowing distinct detection of each PNA probe by conventional fluorescence microscopy. These two PNA beads showed easily detectable co-localization when simultaneously hybridizing to a target nucleic acid...

  4. A fluorescence model of the murine lung for optical detection of pathogenic bacteria

    Science.gov (United States)

    Durkee, Madeleine S.; Cirillo, Jeffrey D.; Maitland, Kristen C.

    2017-07-01

    We present a computer model of intravital excitation and external fluorescence detection in the murine lungs validated with a three-dimensional lung tissue phantom. The model is applied to optical detection of pulmonary tuberculosis infection.

  5. A Fluorescence Based Miniaturized Detection Module for Toxin Producing Algae

    Science.gov (United States)

    Zieger, S. E.; Mistlberger, G.; Troi, L.; Lang, A.; Holly, C.; Klimant, I.

    2016-12-01

    Algal blooms are sensitive to external environmental conditions and may pose a serious threat to marine and human life having an adverse effect on the ecosystem. Harmful algal blooms can produce different toxins, which can lead to massive fish kills or to human disorders. Facing these problems, miniaturized and low-cost instrumentation for an early detection and identification of harmful algae classes has become more important over the last years. 1,2Based on the characteristic pigment pattern of different algae classes, we developed a miniaturized detection module, which is able to detect and identify algae classes after analyzing their spectral behavior. Our device combines features of a flow-cytometer and fluorimeter and is build up as a miniaturized and low-cost device of modular design. Similar to a fluorimeter, it excites cells in the capillary with up to 8 different excitation wavelengths recording the emitted fluorescence at 4 different emission channels. Furthermore, the device operates in a flow-through mode similar to a flow-cytometer, however, using only low-cost elements such as LEDs and photodiodes. Due to its miniaturized design, the sensitivity and selectivity increase, whereas background effects are reduced. With a sampling frequency of 140 Hz, we try to detect and count particular cell events even at a concentration of 2 cells / 7.3 µL illuminated volume. Using a self-learning multivariate algorithm, the data are evaluated autonomously on the device enabling an in-situ analysis. The flexibility in choosing excitation and emission wavelengths as well as the high sampling rate enables laboratory applications such as measuring induction kinetics. However, in its first application, the device is part of an open and modular monitoring system enabling the sensing of chemical compounds such as toxic and essential Hg, Cd, Pb, As and Cu trace metal species, nutrients and species related to the carbon cycle, VOCs and potentially toxic algae classes (FP7

  6. Spectral and physiological information from chlorophyll fluorescence signals in the detection of pine damage

    Energy Technology Data Exchange (ETDEWEB)

    Meinander, O. [Finnish Meteorological Inst., Helsinki (Finland). Air Quality Dept.; Somersalo, S. [Helsinki Univ., Helsinki (Finland). Dept. of Plant Biology

    1995-12-31

    Photosynthesis is often among the first targets of the air pollution stress of plants. As chlorophyll fluorescence is a process competing with photosynthetic electron transport it can be employed to study the potential photosynthetic capacity and to detect damage to the photosynthetic apparatus. Many previous studies have shown that chlorophyll fluorescence can be a powerful tool in the detection of forest damage. In this preliminary study, singular value analysis of the fluorescence induction curves was used together with the traditional way of analyzing fluorescence measurements. The experimental data were collected from ozone and carbon dioxide fumigated Scots pine saplings. (author)

  7. Spectral and physiological information from chlorophyll fluorescence signals in the detection of pine damage

    Energy Technology Data Exchange (ETDEWEB)

    Meinander, O [Finnish Meteorological Inst., Helsinki (Finland). Air Quality Dept.; Somersalo, S [Helsinki Univ., Helsinki (Finland). Dept. of Plant Biology

    1996-12-31

    Photosynthesis is often among the first targets of the air pollution stress of plants. As chlorophyll fluorescence is a process competing with photosynthetic electron transport it can be employed to study the potential photosynthetic capacity and to detect damage to the photosynthetic apparatus. Many previous studies have shown that chlorophyll fluorescence can be a powerful tool in the detection of forest damage. In this preliminary study, singular value analysis of the fluorescence induction curves was used together with the traditional way of analyzing fluorescence measurements. The experimental data were collected from ozone and carbon dioxide fumigated Scots pine saplings. (author)

  8. Cutaneous porphyrins exhibit anti-stokes fluorescence that is detectable in sebum (Conference Presentation)

    Science.gov (United States)

    Tian, Giselle; Zeng, Haishan; Zhao, Jianhua; Wu, Zhenguo; Al Jasser, Mohammed; Lui, Harvey; Mclean, David I.

    2016-02-01

    Porphyrins produced by Propionibacterium acnes represent the principal fluorophore associated with acne, and appear as orange-red luminescence under the Wood's lamp. Assessment of acne based on Wood's lamp (UV) or visible light illumination is limited by photon penetration depth and has limited sensitivity for earlier stage lesions. Inducing fluorescence with near infrared (NIR) excitation may provide an alternative way to assess porphyrin-related skin disorders. We discovered that under 785 nm CW laser excitation PpIX powder exhibits fluorescence emission in the shorter wavelength range of 600-715 nm with an intensity that is linearly dependent on the excitation power. We attribute this shorter wavelength emission to anti-Stokes fluorescence. Similar anti-Stokes fluorescence was also detected focally in all skin-derived samples containing porphyrins. Regular (Stokes) fluorescence was present under UV and visible light excitation on ex vivo nasal skin and sebum from uninflamed acne, but not on nose surface smears or sebum from inflamed acne. Co-registered CW laser-excited anti-Stokes fluorescence and fs laser-excited multi-photon fluorescence images of PpIX powder showed similar features. In the skin samples because of the anti-Stokes effect, the NIR-induced fluorescence was presumably specific for porphyrins since there appeared to be no anti-Stokes emission signals from other typical skin fluorophores such as lipids, keratins and collagen. Anti-Stokes fluorescence under NIR CW excitation is more sensitive and specific for porphyrin detection than UV- or visible light-excited regular fluorescence and fs laser-excited multi-photon fluorescence. This approach also has higher image contrast compared to NIR fs laser-based multi-photon fluorescence imaging. The anti-Stokes fluorescence of porphyrins within sebum could potentially be applied to detecting and targeting acne lesions for treatment via fluorescence image guidance.

  9. Application of fluorescence spectroscopy and imaging in the detection of a photosensitizer in photodynamic therapy

    Science.gov (United States)

    Zang, Lixin; Zhao, Huimin; Zhang, Zhiguo; Cao, Wenwu

    2017-02-01

    Photodynamic therapy (PDT) is currently an advanced optical technology in medical applications. However, the application of PDT is limited by the detection of photosensitizers. This work focuses on the application of fluorescence spectroscopy and imaging in the detection of an effective photosenzitizer, hematoporphyrin monomethyl ether (HMME). Optical properties of HMME were measured and analyzed based on its absorption and fluorescence spectra. The production mechanism of its fluorescence emission was analyzed. The detection device for HMME based on fluorescence spectroscopy was designed. Ratiometric method was applied to eliminate the influence of intensity change of excitation sources, fluctuates of excitation sources and photo detectors, and background emissions. The detection limit of this device is 6 μg/L, and it was successfully applied to the diagnosis of the metabolism of HMME in the esophageal cancer cells. To overcome the limitation of the point measurement using fluorescence spectroscopy, a two-dimensional (2D) fluorescence imaging system was established. The algorithm of the 2D fluorescence imaging system is deduced according to the fluorescence ratiometric method using bandpass filters. The method of multiple pixel point addition (MPPA) was used to eliminate fluctuates of signals. Using the method of MPPA, SNR was improved by about 30 times. The detection limit of this imaging system is 1.9 μg/L. Our systems can be used in the detection of porphyrins to improve the PDT effect.

  10. Detection of hepatocarcinoma in rats by integration of the fluorescence spectrum: Experimental model

    Science.gov (United States)

    Marcassa, J. C.; Ferreira, J.; Zucoloto, S.; Castro E Silva, O., Jr.; Marcassa, L. G.; Bagnato, V. S.

    2006-05-01

    The incorporation of spectroscopic techniques into diagnostic procedures may greatly improve the chances for precise diagnostics. One promising technique is fluorescence spectroscopy, which has recently been used to detect many different types of diseases. In this work, we use laser-induced tissue fluorescence to detect hepatocarcinoma in rats using excitation light at wavelengths of 443 and 532 nm. Hepatocarcinoma was induced chemically in Wistar rats. The collected fluorescence spectrum ranges from the excitation wavelength up to 850 nm. A mathematical procedure carried out on the spectrum determines a figure of merit value, which allows the detection of hepatocarcinoma. The figure of merit involves a procedure which evaluates the ratio between the backscattered excitation wavelength and the broad emission fluorescence band. We demonstrate that a normalization allowed by integration of the fluorescence spectra is a simple operation that may allow the detection of hepatocarcinoma.

  11. Compact point-detection fluorescence spectroscopy system for quantifying intrinsic fluorescence redox ratio in brain cancer diagnostics

    Science.gov (United States)

    Liu, Quan; Grant, Gerald; Li, Jianjun; Zhang, Yan; Hu, Fangyao; Li, Shuqin; Wilson, Christy; Chen, Kui; Bigner, Darell; Vo-Dinh, Tuan

    2011-03-01

    We report the development of a compact point-detection fluorescence spectroscopy system and two data analysis methods to quantify the intrinsic fluorescence redox ratio and diagnose brain cancer in an orthotopic brain tumor rat model. Our system employs one compact cw diode laser (407 nm) to excite two primary endogenous fluorophores, reduced nicotinamide adenine dinucleotide, and flavin adenine dinucleotide. The spectra were first analyzed using a spectral filtering modulation method developed previously to derive the intrinsic fluorescence redox ratio, which has the advantages of insensitivty to optical coupling and rapid data acquisition and analysis. This method represents a convenient and rapid alternative for achieving intrinsic fluorescence-based redox measurements as compared to those complicated model-based methods. It is worth noting that the method can also extract total hemoglobin concentration at the same time but only if the emission path length of fluorescence light, which depends on the illumination and collection geometry of the optical probe, is long enough so that the effect of absorption on fluorescence intensity due to hemoglobin is significant. Then a multivariate method was used to statistically classify normal tissues and tumors. Although the first method offers quantitative tissue metabolism information, the second method provides high overall classification accuracy. The two methods provide complementary capabilities for understanding cancer development and noninvasively diagnosing brain cancer. The results of our study suggest that this portable system can be potentially used to demarcate the elusive boundary between a brain tumor and the surrounding normal tissue during surgical resection.

  12. Engineering of near IR fluorescent albumin nanoparticles for in vivo detection of colon cancer

    Directory of Open Access Journals (Sweden)

    Cohen Sarit

    2012-08-01

    Full Text Available Abstract Background The use of near-infrared (NIR fluorescence imaging techniques has gained great interest for early detection of cancer because water and other intrinsic biomolecules display negligible absorption or autofluorescence in this region. Novel fluorescent nanoparticles with potential to improve neoplasm detection sensitivity may prove to be a valuable tool in early detection of colon tumors. Methods The present study describes the synthesis and use of NIR fluorescent albumin nanoparticles as a diagnostic tool for detection of colon cancer. These fluorescent nanoparticles were prepared by a precipitation process of human serum albumin (HSA in aqueous solution in the presence of a carboxylic acid derivative of the NIR dye IR-783 (CANIR. Tumor-targeting ligands such as peanut agglutinin (PNA, anti-carcinoembryonic antigen antibodies (anti-CEA and tumor associated glycoprotein-72 monoclonal antibodies (anti-TAG-72 were covalently conjugated to the albumin nanoparticles via the surface carboxylate groups by using the carbodiimide activation method. Results and discussion Leakage of the encapsulated dye into PBS containing 4% HSA or human bowel juice was not detected. This study also demonstrates that the encapsulation of the NIR fluorescent dye within the HSA nanoparticles reduces the photobleaching of the dye significantly. Specific colon tumor detection in a mouse model was demonstrated for PNA, anti-CEA and anti-TAG-72 conjugated NIR fluorescent HSA nanoparticles. These bioactive NIR fluorescent albumin nanoparticles also detected invisible tumors that were revealed as pathological only subsequent to histological analysis. Conclusions These results may suggest a significant advantage of NIR fluorescence imaging using NIR fluorescent nanoparticles over regular colonoscopy. In future work we plan to broaden this study by encapsulating cancer drugs, such as paclitaxel and doxorubicin, within these biodegradable NIR fluorescent HSA

  13. Engineering of near IR fluorescent albumin nanoparticles for in vivo detection of colon cancer.

    Science.gov (United States)

    Cohen, Sarit; Margel, Shlomo

    2012-08-14

    The use of near-infrared (NIR) fluorescence imaging techniques has gained great interest for early detection of cancer because water and other intrinsic biomolecules display negligible absorption or autofluorescence in this region. Novel fluorescent nanoparticles with potential to improve neoplasm detection sensitivity may prove to be a valuable tool in early detection of colon tumors. The present study describes the synthesis and use of NIR fluorescent albumin nanoparticles as a diagnostic tool for detection of colon cancer. These fluorescent nanoparticles were prepared by a precipitation process of human serum albumin (HSA) in aqueous solution in the presence of a carboxylic acid derivative of the NIR dye IR-783 (CANIR). Tumor-targeting ligands such as peanut agglutinin (PNA), anti-carcinoembryonic antigen antibodies (anti-CEA) and tumor associated glycoprotein-72 monoclonal antibodies (anti-TAG-72) were covalently conjugated to the albumin nanoparticles via the surface carboxylate groups by using the carbodiimide activation method. Leakage of the encapsulated dye into PBS containing 4% HSA or human bowel juice was not detected. This study also demonstrates that the encapsulation of the NIR fluorescent dye within the HSA nanoparticles reduces the photobleaching of the dye significantly. Specific colon tumor detection in a mouse model was demonstrated for PNA, anti-CEA and anti-TAG-72 conjugated NIR fluorescent HSA nanoparticles. These bioactive NIR fluorescent albumin nanoparticles also detected invisible tumors that were revealed as pathological only subsequent to histological analysis. These results may suggest a significant advantage of NIR fluorescence imaging using NIR fluorescent nanoparticles over regular colonoscopy. In future work we plan to broaden this study by encapsulating cancer drugs, such as paclitaxel and doxorubicin, within these biodegradable NIR fluorescent HSA nanoparticles, in order to use them for both detection as well as therapy of colon

  14. Homogenization optics to improve detectability of a fluorescence response to a single laser pulse: Detection of feces on apples

    Science.gov (United States)

    Fecal contamination of produce is a known food safety risk. Measuring fluorescence responses to UV excitation is an established method for detecting such contamination. One measurement system utilizes a pulsed UV laser to induce a fluorescence response from fecal material and a gated intensified cam...

  15. Detecting aromatic compounds on planetary surfaces using ultraviolet time-resolved fluorescence spectroscopy

    Science.gov (United States)

    Eshelman, E.; Daly, M. G.; Slater, G.; Cloutis, E.

    2018-02-01

    Many aromatic organic molecules exhibit strong and characteristic fluorescence when excited with ultraviolet radiation. As laser excitation in the ultraviolet generates both fluorescence and resonantly enhanced Raman scattering of aromatic vibrational modes, combined Raman and fluorescence instruments have been proposed to search for organic compounds on Mars. In this work the time-resolved fluorescence of a suite of 24 compounds composed of 2-5 ringed alternant, non-alternant, and heterocyclic PAHs was measured. Fluorescence instrumentation with similar specifications to a putative flight instrument was capable of observing the fluorescence decay of these compounds with a sub-ns resolution. Incorporating time-resolved capabilities was also found to increase the ability to discriminate between individual PAHs. Incorporating time-resolved fluorescence capabilities into an ultraviolet gated Raman system intended for a rover or lander can increase the ability to detect and characterize PAHs on planetary surfaces.

  16. Laser induced fluorescence technique for detecting organic matter in East China Sea

    Science.gov (United States)

    Chen, Peng; Wang, Tianyu; Pan, Delu; Huang, Haiqing

    2017-10-01

    A laser induced fluorescence (LIF) technique for fast diagnosing chromophoric dissolved organic matter (CDOM) in water is discussed. We have developed a new field-portable laser fluorometer for rapid fluorescence measurements. In addtion, the fluorescence spectral characteristics of fluorescent constituents (e.g., CDOM, chlorophyll-a) were analyzed with a spectral deconvolution method of bi-Gaussian peak function. In situ measurements by the LIF technique compared well with values measured by conventional spectrophotometer method in laboratory. A significant correlation (R2 = 0.93) was observed between fluorescence by the technique and absorption by laboratory spectrophotometer. Influence of temperature variation on LIF measurement was investigated in lab and a temperature coefficient was deduced for fluorescence correction. Distributions of CDOM fluorescence measured using this technique in the East China Sea coast were presented. The in situ result demonstrated the utility of the LIF technique for rapid detecting dissolved organic matter.

  17. Detection of Pathogenic Biofilms with Bacterial Amyloid Targeting Fluorescent Probe, CDy11

    DEFF Research Database (Denmark)

    Kim, Jun Young; Sahu, Srikanta; Yau, Yin Hoe

    2016-01-01

    Bacterial biofilms are responsible for a wide range of persistent infections. In the clinic, diagnosis of biofilm-associated infections relies heavily on culturing methods, which fail to detect nonculturable bacteria. Identification of novel fluorescent probes for biofilm imaging will greatly...... facilitate diagnosis of pathogenic bacterial infection. Herein, we report a novel fluorescent probe, CDy11 (compound of designation yellow 11), which targets amyloid in the Pseudomonas aeruginosa biofilm matrix through a diversity oriented fluorescent library approach (DOFLA). CDy11 was further demonstrated...

  18. Screen-printed fluorescent sensors for rapid and sensitive anthrax biomarker detection

    International Nuclear Information System (INIS)

    Lee, Inkyu; Oh, Wan-Kyu; Jang, Jyongsik

    2013-01-01

    Highlights: •We fabricated flexible anthrax sensors with a simple screen-printing method. •The sensors selectively detected B. anthracis biomarker. •The sensors provide the visible alarm against anthrax attack. -- Abstract: Since the 2001 anthrax attacks, efforts have focused on the development of an anthrax detector with rapid response and high selectivity and sensitivity. Here, we demonstrate a fluorescence sensor for detecting anthrax biomarker with high sensitivity and selectivity using a screen-printing method. A lanthanide–ethylenediamine tetraacetic acid complex was printed on a flexible polyethersulfone film. Screen-printing deposition of fluorescent detecting moieties produced fluorescent patterns that acted as a visual alarm against anthrax

  19. Development of laser-induced fluorescence detection to assay DNA damage

    International Nuclear Information System (INIS)

    Sharma, M.; Freund, H.G.

    1991-01-01

    A precolumn derivation method has been developed for high performance liquid chromatographic (HPLC) analysis of DNA damage using fluorescence detection. The modified nucleotide, having excised enzymatically from the exposed DNA, is enriched from the normal nucleotides and labeled with a fluorescent reagent. The labeling procedure involves phosphoramidation of the nucleotide with ethylenediamine (EDA) followed by conjugation of the free amino end of the phosphoramidate with 5-dimethylaminonaphthalene 1-sulfonyl chloride, commonly known as Dansyl chloride. The dansylated nucleotide can be analyzed with a sub-picomole limit of detection (LOD) by conventional HPLC using a conventional fluorescence detector. By combining microbore HPLC with laser-induced fluorescence (LIF) detection, the authors present the development of an analytical system that has sub-femtomole LOD for real-time analysis of the dansylated nucleotide. In this paper the application of the developed system in fluorescence postlabeling assay of a small alkyl-modified nucleotide (5-methyl CMP) in calf-thymus DNA is discussed

  20. Poly(o-phenylenediamine) colloid-quenched fluorescent oligonucleotide as a probe for fluorescence-enhanced nucleic acid detection.

    Science.gov (United States)

    Tian, Jingqi; Li, Hailong; Luo, Yonglan; Wang, Lei; Zhang, Yingwei; Sun, Xuping

    2011-02-01

    In this Letter, we demonstrate that chemical oxidation polymerization of o-phenylenediamine (OPD) by potassium bichromate at room temperature results in the formation of submicrometer-scale poly(o-phenylenediamine) (POPD) colloids. Such colloids can absorb and quench dye-labeled single-stranded DNA (ssDNA) very effectively. In the presence of a target, a hybridization event occurs, which produces a double-stranded DNA (dsDNA) that detaches from the POPD surface, leading to recovery of dye fluorescence. With the use of an oligonucleotide (OND) sequence associated with human immunodeficiency virus (HIV) as a model system, we demonstrate the proof of concept that POPD colloid-quenched fluorescent OND can be used as a probe for fluorescence-enhanced nucleic acid detection with selectivity down to single-base mismatch.

  1. Fluorescence in situ hybridization on human metaphase chromosomes detected by near-field scanning optical microscopy

    NARCIS (Netherlands)

    Moers, M.H.P.; Moers, M.H.P.; Kalle, W.H.J.; Kalle, W.H.J.; Ruiter, A.G.T.; Wiegant, J.C.A.G.; Raap, A.K.; Greve, Jan; de Grooth, B.G.; van Hulst, N.F.

    1996-01-01

    Fluorescence in situ hybridization o­n human metaphase chromosomes is detected by near-field scanning optical microscopy. This combination of cytochemical and scanning probe techniques enables the localization and identification of several fluorescently labelled genomic DNA fragments o­n a single

  2. Multispectral fluorescence imaging for detection of bovine feces on Romaine lettuce and baby spinach leaves

    Science.gov (United States)

    Hyperspectral fluorescence imaging with ultraviolet-A excitation was used to evaluate the feasibility of two-waveband fluorescence algorithms for the detection of bovine fecal contaminants on the abaxial and adaxial surfaces of Romaine lettuce and baby spinach leaves. Correlation analysis was used t...

  3. Detection of fecal residue on poultry carcasses by laser induced fluorescence imaging techniques

    Science.gov (United States)

    The potential use of laser-induced fluorescence imaging techniques was investigated for the detection of diluted fecal matters from various parts of the digestive tract, including colon, ceca, small intestine, and duodenum, on poultry carcasses. One of the challenges for using fluorescence imaging f...

  4. Multispectral fluorescence image algorithms for detection of frass on mature tomatoes

    Science.gov (United States)

    A multispectral algorithm derived from hyperspectral line-scan fluorescence imaging under violet LED excitation was developed for the detection of frass contamination on mature tomatoes. The algorithm utilized the fluorescence intensities at five wavebands, 515 nm, 640 nm, 664 nm, 690 nm, and 724 nm...

  5. Using Quenching to Detect Corrosion on Sculptural Metalwork: A Real-World Application of Fluorescence Spectroscopy

    Science.gov (United States)

    Hensen, Cory; Clare, Tami Lasseter; Barbera, Jack

    2018-01-01

    Fluorescence spectroscopy experiments are a frequently taught as part of upper-division teaching laboratories. To expose undergraduate students to an applied fluorescence technique, a corrosion detection method, using quenching, was adapted from authentic research for an instrumental analysis laboratory. In the experiment, students acquire…

  6. Fluorescence imaging in the upper gastrointestinal tract for the detection of dysplasic changes

    Science.gov (United States)

    Sukowski, Uwe; Ebert, Bernd; Ortner, Marianne; Mueller, Karsten; Voderholzer, W.; Weber-Eibel, J.; Dietel, M.; Lochs, Herbert; Rinneberg, Herbert H.

    2001-10-01

    During endoscopy of the esophagus fluorescence images were recorded at a delay of 20 ns after pulsed laser excitation simultaneously with conventional reflected white light images. To label malignant cells (dysplasia, tumor) 5-aminolaevulinic acid was applied prior to fluorescence guided bi-opsy. In this way pre-malignant and malignant lesions were detected not seen previously during routine endoscopy.

  7. Diagnostic accuracy of fluorescence microlymphography for detecting limb lymphedema.

    Science.gov (United States)

    Keo, H H; Husmann, M; Groechenig, E; Willenberg, T; Gretener, S B

    2015-04-01

    Fluorescence microlymphography (FML) is a minimally invasive technique for visualization of the cutaneous lymphatic network. The aim of the study was to assess the accuracy and safety of FML in patients with unilateral lymphedema. This was a cross sectional study. Patients with unilateral leg swelling were assessed and compared with the unaffected contralateral limb. FML was performed in all index legs and the contralateral leg by injecting 0.1 mL of fluorescein isothiocyanate (FITC)-labeled dextran intradermally in both limbs at the same level. The most prominent swelling of the affected limb was the anatomical reference. The spread of the dye in the lymphatic capillaries of the skin was measured in all dimensions by epiluminator intravital microscopy and the maximum dye spread value 10 min after injection was used for statistical analysis. The contralateral leg served as control. Test accuracy and receiver operator characteristic (ROC) analysis was performed to assess threshold values that best predict lymphedema. Between March 2008 and February 2014 seventy patients with unilateral chronic leg swelling were clinically diagnosed with lymphedema. The median age was 45 (IQR 27-56) years. Of those, 46 (65.7%) were female and 71.4% had primary and 28.6% secondary lymphedema. Sensitivity, specificity, positive and negative likelihood ratio, and positive and negative predictive value were 94.3%, 78.6%, 4.40, 0.07, 81.5%, and 93.2% for the 12 mm cut off level and 91.4%, 85.7%, 6.40, 0.10, 86.5%, and 90.9% for the 14 mm cut off level, respectively. The area under the ROC curve was 0.89 (95% CI: 0.83-0.95). No major adverse events were observed. FML is an almost atraumatic and safe technique for detecting lymphedema in patients with leg swelling. In this series the greatest accuracy was observed at a cut off level of ≥14 mm maximum spread. Copyright © 2015 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

  8. Development of a new light collection and detection system optimized for ion beam induced fluorescence microscopy

    International Nuclear Information System (INIS)

    Vanga, Sudheer Kumar; Mi, Zhaohong; Koh, Long Cheng; Tao, Ye; Bettiol, Andrew A.; Watt, Frank

    2015-01-01

    Ion beam induced fluorescence microscopy is a new imaging technique which has the potential to achieve sub-50 nm spatial resolution fluorescence images. Currently the resolution of the technique has been limited to around 150 nm mainly because of inefficient collection and detection of emitted photons from the sample. To overcome this limitation, a new light collection system based on a custom made parabolic mirror is employed to enhance the fluorescence collection. The custom made mirror is designed so as to obtain both structural (scanning transmission ion microscopy) and ion beam induced fluorescence imaging simultaneously. The design and characterization of the parabolic mirror is discussed in detail

  9. Molecular engineering and fluorescence for the detection of toxic cations; Ingenierie moleculaire et fluorescence pour la reconnaissance de cations toxiques

    Energy Technology Data Exchange (ETDEWEB)

    Souchon, V

    2007-11-15

    This work is a part of the 'Toxicologie Nucleaire Environnementale' program which aims at studying the effects on the living of heavy metals or radionuclides involved in nuclear industry. Most particularly, it deals with the design of new fluorescent sensors for the selective detection of Pb{sup 2+}, Cd{sup 2+} and Cs{sup +} in biological media. Several fluorescent calixarenes possessing nitrogen atoms were synthesized and their properties as potential lead sensors were investigated. One of them could be used in experimental conditions close to biological media and new target compounds with amide functional groups were proposed. Many approaches were considered for the design of selective fluorescent sensors for cadmium. On the basis of literature results, many chelating compounds incorporating sulfur atoms were synthesized but showed no significant affinity towards cadmium. On the opposite, compounds functionalized with several pyridine-2'-yl-1,2,3-triazol fluorescent moieties linked to a {beta}-cyclodextrin or a calix[4]arene showed good affinity for cadmium in methanol, but the selectivity was found to be insufficient. In contrast, very satisfying results in terms of both selectivity and sensitivity could be obtained with the commercial calcium sensor Rhod-5N in an aqueous medium at neutral pH. Lastly, micromolar detection limits for the selective detection of caesium were reached in an aqueous medium at neutral pH thanks to a new sulfonated fluorescent calixarene with two appended crown-ethers. An original complexation mechanism was proposed and validated by molecular modelling (DFT). (author)

  10. A PDMS-based cylindrical hybrid lens for enhanced fluorescence detection in microfluidic systems.

    Science.gov (United States)

    Lin, Bor-Shyh; Yang, Yu-Ching; Ho, Chong-Yi; Yang, Han-Yu; Wang, Hsiang-Yu

    2014-02-13

    Microfluidic systems based on fluorescence detection have been developed and applied for many biological and chemical applications. Because of the tiny amount of sample in the system; the induced fluorescence can be weak. Therefore, most microfluidic systems deploy multiple optical components or sophisticated equipment to enhance the efficiency of fluorescence detection. However, these strategies encounter common issues of complex manufacturing processes and high costs. In this study; a miniature, cylindrical and hybrid lens made of polydimethylsiloxane (PDMS) to improve the fluorescence detection in microfluidic systems is proposed. The hybrid lens integrates a laser focusing lens and a fluorescence collecting lens to achieve dual functions and simplify optical setup. Moreover, PDMS has advantages of low-cost and straightforward fabrication compared with conventional optical components. The performance of the proposed lens is first examined with two fluorescent dyes and the results show that the lens provides satisfactory enhancement for fluorescence detection of Rhodamine 6G and Nile Red. The overall increments in collected fluorescence signal and detection sensitivity are more than 220% of those without lens, and the detection limits of Rhodamine 6G and Nile red are lowered to 0.01 μg/mL and 0.05 μg/mL, respectively. The hybrid lens is further applied to the detection of Nile red-labeled Chlorella vulgaris cells and it increases both signal intensity and detection sensitivity by more than 520%. The proposed hybrid lens also dramatically reduces the variation in detected signal caused by the deviation in incident angle of excitation light.

  11. Hybrid phosphorescence and fluorescence native spectroscopy for breast cancer detection.

    Science.gov (United States)

    Alimova, Alexandra; Katz, A; Sriramoju, Vidyasagar; Budansky, Yuri; Bykov, Alexei A; Zeylikovich, Roman; Alfano, R R

    2007-01-01

    Fluorescence and phosphorescence measurements are performed on normal and malignant ex vivo human breast tissues using UV LED and xenon lamp excitation. Tryptophan (trp) phosphorescence intensity is higher in both normal glandular and adipose tissue when compared to malignant tissue. An algorithm based on the ratio of trp fluorescence intensity at 345 nm to phosphorescence intensity at 500 nm is successfully used to separate normal from malignant tissue types. Normal specimens consistently exhibited a low I(345)I(500) ratio (15). The ratio analysis correlates well with histopathology. Intensity ratio maps with a spatial resolution of 0.5 mm are generated in which local regions of malignancy could be identified.

  12. New fluorescent probes for detection and characterization of amyloid fibrils

    Science.gov (United States)

    Gorbenko, Galyna; Trusova, Valeriya; Kirilova, Elena; Kirilov, Georgiy; Kalnina, Inta; Vasilev, Aleksey; Kaloyanova, Stefka; Deligeorgiev, Todor

    2010-08-01

    The applicability of the novel fluorescent probes, aminoderivative of benzanthrone ABM, squaraine dye SQ-1 and polymethine dye V2 to identification and structural analysis of amyloid fibrils has been evaluated using the lysozyme model system in which fibrillar aggregates have been formed in concentrated ethanol solution. The association constant, binding stoichiometry and molar fluorescence of the bound dye have been determined. ABM was found to surpass classical amyloid marker ThT in the sensitivity to the presence of fibrillar aggregates. Resonance energy transfer measurements involving ABM-SQ-1 and SQ-1-V2 donor-acceptor pairs yielded the limits for fractal-like dimension of lysozyme fibrils.

  13. Sensitive detection and separation of fluorescent derivatives using capillary electrophoresis with laser-induced fluorescence detection with 532nm Nd:YAG laser

    International Nuclear Information System (INIS)

    Vrabel, Patrik; Taborsky, Petr; Ryvolova, Marketa; Havel, Josef; Preisler, Jan

    2006-01-01

    Capillary electrophoresis with laser-induced fluorescence detection (CELIF) is a powerful tool for separation and sensitive determination of fluorescent species. Biologically active compounds, such as amino acids, peptides and proteins may exhibit native fluorescence, which is however often low and/or an expensive laser is required for excitation in UV. Therefore, labelling of the analytes with a fluorescent dye is usually necessary. In this work, a home-built CELIF instrument with diode pumped frequency-doubled continuous wave Nd:YAG excitation laser with feedback power regulation (532nm) was constructed. The suitability of this type of laser for LIF detection in a separation method was found excellent. A limit of detection (LOD) (S/N=3) of 2x10 -13 mol/l was achieved with rhodamine B, which is comparable to those obtained using similar instruments with Ar + laser [Y.F. Cheng, N.J. Dovichi, Science 242 (1988) 562, E.S. Yeung et al., J. Chromatogr. 608 (1992) 73]. LOD of a protein derivatized according to modified procedures [M.J. Little et al., Anal. Chim. Acta 339 (1997) 279, A. Chersi et al., Biochim. Biophys. Acta 1336 (1997) 83] was determined. Detection of the derivatives was found to be limited by insufficient reaction recovery at low analyte concentration, chemical noise, separation efficiency and quality of the derivatizing reagent rather than by the detector performance. As a consequence, a huge gap between the detection ability of CELIF instruments and LOD determined in real samples is revealed

  14. Selective detection of heavy metal ions by calixarene-based fluorescent molecular sensors

    Science.gov (United States)

    Zhang, Haitao; Faye, Djibril; Zhang, Han; Lefevre, Jean-Pierre; Delaire, J. A.; Leray, Isabelle

    2012-06-01

    The synthesis, spectroscopic characterization and complexing properties of calixarene-based fluorescent sensors are reported. The calixarene bearing four dansyl fluorophores (Calix-DANS4) exhibits a very high affinity for the detection of lead. A fluorimetric micro-device based on the use of a Y-shape microchannel was developed and allows lead detection with a 5 ppb detection limit. For mercury detection, a fluorescent molecular sensor containing a calixarene anchored with four 8-quinolinoloxy groups (Calix-Q) has been synthesized. The absorption and fluorescence spectra of this sensor are sensitive to the presence of metal cations. An efficient fluorescence quenching is observed upon mercury complexation because of a photoinduced electron transfer from the fluorophore to the bound mercury. Calix-Q shows a high selectivity towards Hg2+ over interfering cations (Na+, K+, Ca2+, Cu2+, Zn2+, Cd2+ and Pb2+) and a 70 ppb sensitivity.

  15. DETECTION OF BACTERIAL BIOFILM ON STAINLESS STEEL BY HYPERSPECTRAL FLUORESCENCE IMAGING

    Science.gov (United States)

    In this study, hyperspectral fluorescence imaging techniques were investigated for detection of microbial biofilm on stainless steel plates typically used to manufacture food processing equipment. Stainless steel coupons were immersed in bacterium cultures consisting of nonpathogenic E. coli, Pseudo...

  16. Design of a confocal microfluidic particle sorter using fluorescent photon burst detection

    NARCIS (Netherlands)

    Kunst, B.H.; Schots, A.; Visser, A.J.W.G.

    2004-01-01

    An instrumental system is described for detecting and sorting single fluorescent particles such as microspheres, bacteria, viruses, or even smaller macromolecules in a flowing liquid. The system consists of microfluidic chips (biochips), computer controlled high voltage power supplies, and a

  17. Highly selective and sensitive fluorescent chemosensor for femtomolar detection of silver ion in aqueous medium

    OpenAIRE

    Arulraj, Abraham Daniel; Devasenathipathy, Rajkumar; Chen, Shen-Ming; Vasantha, Vairathevar Sivasamy; Wang, Sea-Fue

    2015-01-01

    The chemical sensing for the trace level detection of silver ion in aqueous solution still remains a challenge using simple, rapid, and inexpensive method. We report that thionine can be used as a fluorescent probe for the detection of Ag+ ion. The successive addition of Ag+ ion to the solution containing thionine quenches (turns-off) the fluorescence intensity of thionine. Association and quenching constants have been estimated by the Benesi–Hildebrand method and Stern–Volmer plot, respectiv...

  18. A novel fluorescent in situ hybridization technique for detection of Rickettsia spp. in archival samples

    DEFF Research Database (Denmark)

    Svendsen, Claus Bo; Boye, Mette; Struve, Carsten

    2009-01-01

    A novel, sensitive and specific method for detecting Rickettsia spp. in archival samples is described. The method involves the use of fluorescently marked oligonucleotide probes for in situ hybridization. Specific hybridization of Ricekttsia was found without problems of cross-reactions with bact......A novel, sensitive and specific method for detecting Rickettsia spp. in archival samples is described. The method involves the use of fluorescently marked oligonucleotide probes for in situ hybridization. Specific hybridization of Ricekttsia was found without problems of cross...

  19. Performance of LED fluorescence microscopy for the detection of ...

    African Journals Online (AJOL)

    Introduction: Ziehl-Neelsen (ZN) bright-field microscopy is time-consuming, with poor sensitivity, even under optimal conditions. Introduction of Primo Star iLED fluorescent microscopy (FM) may improve TB case finding at referral hospitals in Rwanda. The study aimed to determine the acceptability and effectiveness of iLED ...

  20. Beta-induced fluorescence detection in liquid chromatography

    International Nuclear Information System (INIS)

    Malcolme-Lawes, D.J.; Massey, S.; Warwick, P.

    1981-01-01

    A theoretical analysis of beta-induced fluorescence is used to determine the factors which influence the sensitivity of the technique as applied to liquid chromatography. Equations are presented for detector response and for signal-to-noise ratios and the theoretical response for a typical detector is compared with experimentally determined values. (author)

  1. Detection of vegetation stress from laser-induced fluorescence signatures

    International Nuclear Information System (INIS)

    Subhash, N.

    1995-01-01

    The in vivo laser-induced fluorescence (LIF) signatures of UV irradiated Salvia splendens plants were measured using an Optical Multichannel Analyser (OMA) system with Nitrogen laser excitation. The LIF spectra which consisted of the blue-green and the red chlorophyll bands were analysed with a non-linear interactive procedure using Gaussian spectral functions. The fluorescence intensity ratios of the various bands obtained from curve fitted parameters were found to be more sensitive to changes in the photosynthetic activity of the plant. The variation in the intensity ratio for the chlorophyll bands for nutrient stressed sunflower, cotton and groundnut plants as well as the nutrient and water stressed rice plants are also presented. It is observed that vegetation stress not only changes the fluorescence intensity ratios and the vitality index of the plant but also changes the peak position of the emission bands, in some cases. It is also seen that analysis of the fluorescence spectra in vegetation remote sensing applications would require a deconvolution procedure to evaluate the exact contribution of each band in the total spectra. (author). 23 refs, 8 figs, 5 tabs

  2. Quantitative wavelenght-resolved fluorescence detection for microchip capillary electrophoresis

    NARCIS (Netherlands)

    Götz, S.

    2006-01-01

    This thesis describes the development and application of a new wavelengthresolved CCD-based fluorescence detector for microchip separations. In recent years, miniaturization has been one of the major trends in the development of new analytical separation systems. As the manipulated sample amounts

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

    Science.gov (United States)

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

    2011-04-01

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

  4. Sentinel lymph nodes detection with an imaging system using Patent Blue V dye as fluorescent tracer

    Science.gov (United States)

    Tellier, F.; Steibel, J.; Chabrier, R.; Rodier, J. F.; Pourroy, G.; Poulet, P.

    2013-03-01

    Sentinel lymph node biopsy is the gold standard to detect metastatic invasion from primary breast cancer. This method can help patients avoid full axillary chain dissection, thereby decreasing the risk of morbidity. We propose an alternative to the traditional isotopic method, to detect and map the sentinel lymph nodes. Indeed, Patent Blue V is the most widely used dye in clinical routine for the visual detection of sentinel lymph nodes. A Recent study has shown the possibility of increasing the fluorescence quantum yield of Patent Blue V, when it is bound to human serum albumin. In this study we present a preclinical fluorescence imaging system to detect sentinel lymph nodes labeled with this fluorescent tracer. The setup is composed of a black and white CCD camera and two laser sources. One excitation source with a laser emitting at 635 nm and a second laser at 785 nm to illuminate the region of interest. The prototype is operated via a laptop. Preliminary experiments permitted to determine the device sensitivity in the μmol.L-1 range as regards the detection of PBV fluorescence signals. We also present a preclinical evaluation performed on Lewis rats, during which the fluorescence imaging setup detected the accumulation and fixation of the fluorescent dye on different nodes through the skin.

  5. Fluorescent Gold Nanoprobes for the Sensitive and Selective Detection for Hg2+

    Directory of Open Access Journals (Sweden)

    Chai Fang

    2010-01-01

    Full Text Available Abstract A simple, cost-effective yet rapid and sensitive sensor for on-site and real-time Hg2+ detection based on bovine serum albumin functionalized fluorescent gold nanoparticles as novel and environmentally friendly fluorescent probes was developed. Using this probe, aqueous Hg2+ can be detected at 0.1 nM in a facile way based on fluorescence quenching. This probe was also applied to determine the Hg2+ in the lake samples, and the results demonstrate low interference and high sensitivity.

  6. A novel dansyl-based fluorescent probe for highly selective detection of ferric ions.

    Science.gov (United States)

    Yang, Min; Sun, Mingtai; Zhang, Zhongping; Wang, Suhua

    2013-02-15

    A novel dansyl-based fluorescent probe was synthesized and characterized. It exhibits high selectivity and sensitivity towards Fe(3+) ion. This fluorescent probe is photostable, water soluble and pH insensitive. The limit of detection is found to be 0.62 μM. These properties make it a good fluorescent probe for Fe(3+) ion detection in both chemical and biological systems. Spike recovery test confirms its practical application in tap water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Fluorescence detection of a protein-bound 2Fe2S cluster.

    Science.gov (United States)

    Hoff, Kevin G; Goodlitt, Rochelle; Li, Rui; Smolke, Christina D; Silberg, Jonathan J

    2009-03-02

    A fluorescent biosensor is described for 2Fe2S clusters that is composed of green fluorescent protein (GFP) fused to glutaredoxin 2 (Grx2), as illustrated here. 2Fe2S detection is based on the reduction of GFP fluorescence upon the 2Fe2S-induced dimerization of GFP-Grx2. This assay is sufficiently sensitive to detect submicromolar changes in 2Fe2S levels, thus making it suitable for high-throughput measurements of metallocluster degradation and synthesis reactions.

  8. A ratiometric nanoprobe based on silver nanoclusters and carbon dots for the fluorescent detection of biothiols

    Science.gov (United States)

    Zhang, Shuming; Lin, Bixia; Yu, Ying; Cao, Yujuan; Guo, Manli; Shui, Lingling

    2018-04-01

    Ratiometric fluorescent probes could eliminate the influence from experimental factors and improve the detection accuracy. In this article, a ratiometric nanoprobe was constructed based on silver nanoclusters (AgNCs) with nitrogen-doped carbon dots (NCDs) and used for the detection of biothiols. The fluorescence peak of AgNCs was observed at 650 nm with excitation wavelength at 370 nm. In order to construct the ratiometric fluorescent probe, NCDs with the excitation and emission wavelengths at 370 nm and 450 nm were selected. After adding AgNCs, the fluorescence of NCDs was quenched. The mechanism of the fluorescence quenching was studied by fluorescence, UV-Vis absorption and the fluorescence lifetime spectra. The results indicated that the quenching could be ascribed to the inner filter effect (IFE). With the addition of biothiols, the fluorescence of AgNCs at 650 nm decreased due to the breakdown of AgNCs, and the fluorescence of NCDs at 450 nm recovered accordingly. Thus, the relationship between the ratio of the fluorescence intensities (I450/I650) and biothiol concentration was used to establish the determination method for biothiols. Cysteine (Cys) was taken as the model of biothiols, and the working curve for Cys was I450/I650 = 0.60CCys - 1.86 (CCys: μmol/L) with the detection limit of 0.14 μmol/L (S/N = 3). Then, the method was used for the detection of Cys in human urine and serum samples with satisfactory accuracy and recovery ratios. Furthermore, the probe could be applied for the visual semi-quantitative determination of Cys by naked eyes.

  9. Sensitive detection of alkaline phosphatase by switching on gold nanoclusters fluorescence quenched by pyridoxal phosphate.

    Science.gov (United States)

    Halawa, Mohamed Ibrahim; Gao, Wenyue; Saqib, Muhammad; Kitte, Shimeles Addisu; Wu, Fengxia; Xu, Guobao

    2017-09-15

    In this work, we designed highly sensitive and selective luminescent detection method for alkaline phosphatase using bovine serum albumin functionalized gold nanoclusters (BSA-AuNCs) as the nanosensor probe and pyridoxal phosphate as the substrate of alkaline phosphatase. We found that pyridoxal phosphate can quench the fluorescence of BSA-AuNCs and pyridoxal has little effect on the fluorescence of BSA-AuNCs. The proposed mechanism of fluorescence quenching by PLP was explored on the basis of data obtained from high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), UV-vis spectrophotometry, fluorescence spectroscopy, fluorescence decay time measurements and circular dichroism (CD) spectroscopy. Alkaline phosphatase catalyzes the hydrolysis of pyridoxal phosphate to generate pyridoxal, restoring the fluorescence of BSA-AuNCs. Therefore, a recovery type approach has been developed for the sensitive detection of alkaline phosphatase in the range of 1.0-200.0U/L (R 2 =0.995) with a detection limit of 0.05U/L. The proposed sensor exhibit excellent selectivity among various enzymes, such as glucose oxidase, lysozyme, trypsin, papain, and pepsin. The present switch-on fluorescence sensing strategy for alkaline phosphatase was successfully applied in human serum plasma with good recoveries (100.60-104.46%), revealing that this nanosensor probe is a promising tool for ALP detection. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. A zinc fluorescent sensor used to detect mercury (II) and hydrosulfide.

    Science.gov (United States)

    Jung, Jae Min; Lee, Jae Jun; Nam, Eunju; Lim, Mi Hee; Kim, Cheal; Harrison, Roger G

    2017-05-05

    A zinc sensor based on quinoline and morpholine has been synthesized. The sensor selectively fluoresces in the presence of Zn 2+ , while not for other metal ions. Absorbance changes in the 350nm region are observed when Zn 2+ binds, which binds in a 1:1 ratio. The sensor fluoresces due to Zn 2+ above pH values of 6.0 and in the biological important region. The Zn 2+ -sensor complex has the unique ability to detect both Hg 2+ and HS - . The fluorescence of the Zn 2+ -sensor complex is quenched when it is exposed to aqueous solutions of Hg 2+ with sub-micromolar detection levels for Hg 2+ . The fluorescence of the Zn 2+ -sensor complex is also quenched by aqueous solutions of hydrosulfide. The sensor was used to detect Zn 2+ and Hg 2+ in living cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Fluorescent QDs-polystyrene composite nanospheres for highly efficient and rapid protein antigen detection

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Changhua; Mao, Mao [Henan University, Key Laboratory for Special Functional Materials of the Ministry of Education (China); Yuan, Hang [Tsinghua University, Life Science Division, Graduate School at Shenzhen (China); Shen, Huaibin [Henan University, Key Laboratory for Special Functional Materials of the Ministry of Education (China); Wu, Feng; Ma, Lan, E-mail: malan@sz.tsinghua.edu.cn [Tsinghua University, Life Science Division, Graduate School at Shenzhen (China); Li, Lin Song, E-mail: lsli@henu.edu.cn [Henan University, Key Laboratory for Special Functional Materials of the Ministry of Education (China)

    2013-09-15

    In this paper, high-quality carboxyl-functionalized fluorescent (red, green, and blue emitting) nanospheres (46-103 nm) consisting of hydrophobic quantum dots (QDs) and polystyrene were prepared by a miniemulsion polymerization approach. This miniemulsion polymerization approach induced a homogeneous distribution and high aqueous-phase transport efficiency of fluorescent QDs in composite nanospheres, which proved the success of our encoding QDs strategy. The obtained fluorescent nanospheres exhibited high stability in aqueous solution under a wide range of pH, different salt concentrations, PBS buffer, and thermal treatment at 80 Degree-Sign C. Based on the red emitting composite nanosphere, we performed fluorescent lateral flow immunoassay (LFIA) strips for high-sensitivity and rapid alpha-fetal protein detection. The detection limit reached 0.1 ng/mL, which was 200 times higher than commercial colloidal gold-labeled LFIA strips, and it reached similar detection level in enzyme-linked immunosorbent assay kit.

  12. Detection of mechanical and disease stresses in citrus plants by fluorescence spectroscopy

    Science.gov (United States)

    Belasque, J., Jr.; Gasparoto, M. C. G.; Marcassa, L. G.

    2008-04-01

    We have investigated the detection of mechanical and disease stresses in citrus plants (Citrus limonia [L.] Osbeck) using laser-induced fluorescence spectroscopy. Due to its economic importance we have chosen to investigate the citrus canker disease, which is caused by the Xanthomonas axonopodis pv. citri bacteria. Mechanical stress was also studied because it plays an important role in the plant's infection by such bacteria. A laser-induced fluorescence spectroscopy system, composed of a spectrometer and a 532 nm10 mW excitation laser was used to perform fluorescence spectroscopy. The ratio of two chlorophyll fluorescence bands allows us to detect and discriminate between mechanical and disease stresses. This ability to discriminate may have an important application in the field to detect citrus canker infected trees.

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

    Science.gov (United States)

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

    2018-02-01

    Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H 2 O 2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H 2 O 2 . We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H 2 O 2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

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

    Science.gov (United States)

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

    2018-02-01

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

  15. Automated detection of fluorescent cells in in-resin fluorescence sections for integrated light and electron microscopy.

    Science.gov (United States)

    Delpiano, J; Pizarro, L; Peddie, C J; Jones, M L; Griffin, L D; Collinson, L M

    2018-04-26

    Integrated array tomography combines fluorescence and electron imaging of ultrathin sections in one microscope, and enables accurate high-resolution correlation of fluorescent proteins to cell organelles and membranes. Large numbers of serial sections can be imaged sequentially to produce aligned volumes from both imaging modalities, thus producing enormous amounts of data that must be handled and processed using novel techniques. Here, we present a scheme for automated detection of fluorescent cells within thin resin sections, which could then be used to drive automated electron image acquisition from target regions via 'smart tracking'. The aim of this work is to aid in optimization of the data acquisition process through automation, freeing the operator to work on other tasks and speeding up the process, while reducing data rates by only acquiring images from regions of interest. This new method is shown to be robust against noise and able to deal with regions of low fluorescence. © 2018 The Authors. Journal of Microscopy published by JohnWiley & Sons Ltd on behalf of Royal Microscopical Society.

  16. Intermolecular G-quadruplex structure-based fluorescent DNA detection system.

    Science.gov (United States)

    Zhou, Hui; Wu, Zai-Sheng; Shen, Guo-Li; Yu, Ru-Qin

    2013-03-15

    Adopting multi-donors to pair with one acceptor could improve the performance of fluorogenic detection probes. However, common dyes (e.g., fluorescein) in close proximity to each other would self-quench the fluorescence, and the fluorescence is difficult to restore. In this contribution, we constructed a novel "multi-donors-to-one acceptor" fluorescent DNA detection system by means of the intermolecular G-quadruplex (IGQ) structure-based fluorescence signal enhancement combined with the hairpin oligonucleotide. The novel IGQ-hairpin system was characterized using the p53 gene as the model target DNA. The proposed system showed an improved assay performance due to the introduction of IGQ-structure into fluorescent signaling probes, which could inhibit the background fluorescence and increase fluorescence restoration amplitude of fluoresceins upon target DNA hybridization. The proof-of-concept scheme is expected to provide new insight into the potential of G-quadruplex structure and promote the application of fluorescent oligonucleotide probes in fundamental research, diagnosis, and treatment of genetic diseases. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Synthesis and characterization of near IR fluorescent albumin nanoparticles for optical detection of colon cancer

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Sarit; Pellach, Michal [Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900 (Israel); Kam, Yossi [Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, P.O. Box 12065, Jerusalem 91120 (Israel); Grinberg, Igor; Corem-Salkmon, Enav [Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900 (Israel); Rubinstein, Abraham [Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, P.O. Box 12065, Jerusalem 91120 (Israel); Margel, Shlomo, E-mail: shlomo.margel@mail.biu.ac.il [Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900 (Israel)

    2013-03-01

    Near IR (NIR) fluorescent human serum albumin (HSA) nanoparticles hold great promise as contrast agents for tumor diagnosis. HSA nanoparticles are considered to be biocompatible, non-toxic and non-immunogenic. In addition, NIR fluorescence properties of these nanoparticles are important for in vivo tumor diagnostics, with low autofluorescence and relatively deep penetration of NIR irradiation due to low absorption of biomatrices. The present study describes the synthesis of new NIR fluorescent HSA nanoparticles, by entrapment of a NIR fluorescent dye within the HSA nanoparticles, which also significantly increases the photostability of the dye. Tumor-targeting ligands such as peanut agglutinin (PNA) and anti-carcinoembryonic antigen antibodies (anti-CEA) were covalently conjugated to the NIR fluorescent albumin nanoparticles, increasing the potential fluorescent signal in tumors with upregulated corresponding receptors. Specific colon tumor detection by the NIR fluorescent HSA nanoparticles was demonstrated in a chicken embryo model and a rat model. In future work we also plan to encapsulate cancer drugs such as doxorubicin within the NIR fluorescent HSA nanoparticles for both colon cancer imaging and therapy. - Highlights: Black-Right-Pointing-Pointer Near IR human serum albumin nanoparticles were synthesized and characterized. Black-Right-Pointing-Pointer Nanoparticles were shown to be physically and chemically stable and photostable. Black-Right-Pointing-Pointer Tumor-targeting ligands were covalently conjugated to the nanoparticles. Black-Right-Pointing-Pointer Specific colon cancer tumor detection was demonstrated in chicken-embryo and rat models.

  18. Synthesis and characterization of near IR fluorescent albumin nanoparticles for optical detection of colon cancer

    International Nuclear Information System (INIS)

    Cohen, Sarit; Pellach, Michal; Kam, Yossi; Grinberg, Igor; Corem-Salkmon, Enav; Rubinstein, Abraham; Margel, Shlomo

    2013-01-01

    Near IR (NIR) fluorescent human serum albumin (HSA) nanoparticles hold great promise as contrast agents for tumor diagnosis. HSA nanoparticles are considered to be biocompatible, non-toxic and non-immunogenic. In addition, NIR fluorescence properties of these nanoparticles are important for in vivo tumor diagnostics, with low autofluorescence and relatively deep penetration of NIR irradiation due to low absorption of biomatrices. The present study describes the synthesis of new NIR fluorescent HSA nanoparticles, by entrapment of a NIR fluorescent dye within the HSA nanoparticles, which also significantly increases the photostability of the dye. Tumor-targeting ligands such as peanut agglutinin (PNA) and anti-carcinoembryonic antigen antibodies (anti-CEA) were covalently conjugated to the NIR fluorescent albumin nanoparticles, increasing the potential fluorescent signal in tumors with upregulated corresponding receptors. Specific colon tumor detection by the NIR fluorescent HSA nanoparticles was demonstrated in a chicken embryo model and a rat model. In future work we also plan to encapsulate cancer drugs such as doxorubicin within the NIR fluorescent HSA nanoparticles for both colon cancer imaging and therapy. - Highlights: ► Near IR human serum albumin nanoparticles were synthesized and characterized. ► Nanoparticles were shown to be physically and chemically stable and photostable. ► Tumor-targeting ligands were covalently conjugated to the nanoparticles. ► Specific colon cancer tumor detection was demonstrated in chicken-embryo and rat models.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-15

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

  20. A new miniaturized multiarray biosensor system for fluorescence detection

    International Nuclear Information System (INIS)

    Tibuzzi, A; Rea, G; Pezzotti, G; Esposito, D; Johanningmeier, U; Giardi, M T

    2007-01-01

    A miniaturized biosensor-based optical instrument has been designed and fabricated for multiarray fluorescence measurements of several biomediators in series, with applications in environmental monitoring and agrofood analysis. It is a multicell system featuring two arrays of five static cells (1 x 1 x 2 cm 3 ) which are sealed to avoid contamination. Every cell is made up by two modular sections: the bottom compartment with optical LED light excitations and a photodiode detector for fluorescence emission capture, and the top biocompatible compartment where the biosample is deposited. The system (0.250 kg without batteries and case, 100 x 100 x 150 mm 3 internal case dimensions) is equipped with electronic control boards, a flash memory card for automatic data storage, and internal batteries, thus being portable and versatile. The instrument allows one to perform simultaneous and multiparametric analyses and offers a large applicability in biosensor technology. The first prototype has been implemented with genetically modified oxygenic photosynthetic algae that were employed in the instrument experimental testing by monitoring pesticide pollution in water. Pesticides modify the photosystem II (PSII) activity in terms of fluorescence quenching. The PSII complex features a natural nanostructure and can be considered a sophisticated molecular device. Results from measurements employing several PSII mutants and six different pesticides at increasing concentrations and incubation times are presented and discussed

  1. Chair-side detection of Prevotella Intermedia in mature dental plaque by its fluorescence.

    Science.gov (United States)

    Nomura, Yoshiaki; Takeuchi, Hiroaki; Okamoto, Masaaki; Sogabe, Kaoru; Okada, Ayako; Hanada, Nobuhiro

    2017-06-01

    Prevotella intermedia/nigrescens is one of the well-known pathogens causing periodontal diseases, and the red florescence excited by the visible blue light caused by the protoporphyrin IX in the bacterial cells could be useful for the chair-side detection. The aim of this study was to evaluated levels of periodontal pathogen, especially P. intermedia in clinical samples of red fluorescent dental plaque. Thirty two supra gingival plaque samples from six individuals were measured its fluorescence at 640nm wavelength excited by 409nm. Periodontopathic bacteria were counted by the Invader PLUS PCR assay. Co-relations the fluorescence intensity and bacterial counts were analyzed by Person's correlation coefficient and simple and multiple regression analysis. Positive and negative predictive values of the fluorescence intensities for with or without P. intermedia in supragingival plaque was calculated. When relative fluorescence unit (RFU) were logarithmic transformed, statistically significant linear relations between RFU and bacterial counts were obtained for P. intermedia, Porphyromonas gingivalis and Tannerella forsythia. By the multiple regression analysis, only P. intermedia had statistically significant co-relation with fluorescence intensities. All of the fluorescent dental plaque contained P. intermedia m. In contrast, 28% of non-fluorescent plaques contained P. intermedia. To check the fluorescence dental plaque in the oral cavity could be the simple chair-side screening of the mature dental plaque before examining the periodontal pathogens especially P. intermedia by the PCR method. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Fluorescence hyperspectral imaging technique for foreign substance detection on fresh-cut lettuce.

    Science.gov (United States)

    Mo, Changyeun; Kim, Giyoung; Kim, Moon S; Lim, Jongguk; Cho, Hyunjeong; Barnaby, Jinyoung Yang; Cho, Byoung-Kwan

    2017-09-01

    Non-destructive methods based on fluorescence hyperspectral imaging (HSI) techniques were developed to detect worms on fresh-cut lettuce. The optimal wavebands for detecting the worms were investigated using the one-way ANOVA and correlation analyses. The worm detection imaging algorithms, RSI-I (492-626)/492 , provided a prediction accuracy of 99.0%. The fluorescence HSI techniques indicated that the spectral images with a pixel size of 1 × 1 mm had the best classification accuracy for worms. The overall results demonstrate that fluorescence HSI techniques have the potential to detect worms on fresh-cut lettuce. In the future, we will focus on developing a multi-spectral imaging system to detect foreign substances such as worms, slugs and earthworms on fresh-cut lettuce. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

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

    Science.gov (United States)

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

    2014-07-01

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

  4. DNA-hosted copper nanoclusters/graphene oxide based fluorescent biosensor for protein kinase activity detection.

    Science.gov (United States)

    Wang, Mengke; Lin, Zihan; Liu, Qing; Jiang, Shan; Liu, Hua; Su, Xingguang

    2018-07-05

    A novel fluorescent biosensor for protein kinase activity (PKA) detection was designed by applying double-strands DNA-hosted copper nanoclusters (dsDNA-CuNCs) and graphene oxide (GO). One DNA strand of the dsDNA consisted of two domains, one domain can hybridize with another complementary DNA strand to stabilize the fluorescent CuNCs and another domain was adenosine 5'-triphosphate (ATP) aptamer. ATP aptamer of the dsDNA-CuNCs would be spontaneously absorbed onto the GO surface through π-π stacking interactions. Thus GO can efficiently quench the fluorescence (FL) of dsDNA-CuNCs through fluorescence resonance energy transfer (FRET). In the present of ATP, ATP specifically combined with ATP aptamer to form ATP-ATP aptamer binding complexes, which had much less affinity to GO, resulting in the fluorescence recovery of the system. Nevertheless, in the presence of PKA, ATP could be translated into ADP and ADP could not combine with ATP aptamer resulting in the fluorescence quenching of dsDNA-CuNCs again. According to the change of the fluorescence signal, PKA activity could be successfully monitored in the range of 0.1-5.0 U mL -1 with a detection limit (LOD) of 0.039 U mL -1 . Besides, the inhibitory effect of H-89 on PKA activity was studied. The sensor was performed for PKA activity detection in cell lysates with satisfactory results. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Oligonucleotide-stabilized fluorescent silver nanoclusters for the specific and sensitive detection of biotin.

    Science.gov (United States)

    Xiong, Xiaoli; Tang, Yan; Zhao, Jingjin; Zhao, Shulin

    2016-02-21

    A novel biotin fluorescent probe based on oligonucleotide-stabilized silver nanoclusters (DNA-AgNCs) was synthesized by employing a biotinylated cytosine-rich sequence as a synthesized template. The fluorescence properties of the DNA-AgNCs are related to the modified position of the DNA. When biotin is linked to the middle thymine base of the DNA sequence, the DNA-AgNCs emit the strongest fluorescence. Moreover, the stability of the DNA-AgNCs was affected by avidin through biotin-avidin binding, quenching the fluorescence of the DNA-AgNCs. In contrast, if free biotin is further introduced into this system, the quenching is apparently weakened by competition, leading to the restoration of fluorescence. This phenomenon can be utilized for the detection of biotin. Under the optimal conditions, the fluorescence recovery is linearly proportional to the concentration of biotin in the range of 10 nM-1.0 μM with a detection limit of 6.0 nM. This DNA-AgNCs probe with excellent fluorescent properties is sensitive and selective for the detection of biotin and has been applied for the determination of biotin in wheat flour.

  6. Intraoperative Detection of Superficial Liver Tumors by Fluorescence Imaging Using Indocyanine Green and 5-aminolevulinic Acid.

    Science.gov (United States)

    Kaibori, Masaki; Matsui, Kosuke; Ishizaki, Morihiko; Iida, Hiroya; Okumura, Tadayoshi; Sakaguchi, Tatsuma; Inoue, Kentaro; Ikeura, Tsukasa; Asano, Hiroaki; Kon, Masanori

    2016-04-01

    Indocyanine green (ICG) and the porphyrin precursor 5-aminolevulinic acid (5-ALA) have been approved as fluorescence imaging agents in the clinical setting. This study evaluated the usefulness of fluorescence imaging with both ICG and 5-ALA for intraoperative identification of latent small liver tumors. There were 48 patients who had main tumors within 5 mm of the liver surface. 5-ALA hydrochloride was orally administered to patients 3 h before surgery. ICG had been intravenously injected within 14 days prior to surgery. Intraoperatively, after visual inspection, manual palpation and ultrasonography fluorescence images of the liver surface were obtained with ICG and 5-ALA prior to resection. With ICG, the sensitivity, specificity and accuracy for detecting the preoperatively identified main tumors were 96%, 50% and 94%, respectively. Twelve latent small tumors were newly detected on the liver surface using ICG, five of which proved to be carcinomas. With 5-ALA, the sensitivity, specificity and accuracy for detecting the main tumors were 57%, 100% and 58%, respectively. Five latent small tumors were newly detected using 5-ALA; all were carcinomas. Overall, five new tumors were detected by both ICG and 5-ALA fluorescence imaging; two were hepatocellular carcinomas (HCCs) and three were metastases of colorectal cancer. The sensitivity and specificity of ICG fluorescence imaging for main tumor detection were relatively high and low, respectively, but the opposite was true of 5-ALA imaging. Fluorescence imaging using 5-ALA may provide greater specificity in the detection of surface-invisible malignant liver tumors than using ICG fluorescence imaging alone. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  7. High-performance fluorescence-encoded magnetic microbeads as microfluidic protein chip supports for AFP detection

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Xiaoqun [School of Life Sciences, Tianjin Engineering Center of Micro-Nano Biomaterials and Detection-Treatment Technology, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300072 (China); Yan, Huan; Yang, Jiumin [Department of Laboratory Medicine, Tianjin Medical University General Hospital, Tianjin, 300052 (China); Wu, Yudong; Zhang, Jian; Yao, Yingyi [School of Life Sciences, Tianjin Engineering Center of Micro-Nano Biomaterials and Detection-Treatment Technology, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300072 (China); Liu, Ping [Bioscience (Tianjin) Diagnostic Technology CO., LTD, Tianjin, 300300 (China); Wang, Huiquan [Department of Biomedical Engineering, School of Electronics and Information Engineering, Tianjin Polytechnic University, Tianjin, 300387 (China); Hu, Zhidong, E-mail: huzhidong27@163.com [Department of Laboratory Medicine, Tianjin Medical University General Hospital, Tianjin, 300052 (China); Chang, Jin, E-mail: jinchang@tju.edu.cn [School of Life Sciences, Tianjin Engineering Center of Micro-Nano Biomaterials and Detection-Treatment Technology, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300072 (China)

    2016-10-05

    Fluorescence-encoded magnetic microbeads (FEMMs), with the fluorescence encoding ability of quantum dots (QDs) and magnetic enrichment and separation functions of Fe{sub 3}O{sub 4} nanoparticles, have been widely used for multiple biomolecular detection as microfluidic protein chip supports. However, the preparation of FEMMs with long-term fluorescent encoding and immunodetection stability is still a challenge. In this work, we designed a novel high-temperature chemical swelling strategy. The QDs and Fe{sub 3}O{sub 4} nanoparticles were effectively packaged into microbeads via the thermal motion of the polymer chains and the hydrophobic interaction between the nanoparticles and microbeads. The FEMMs obtained a highly uniform fluorescent property and long-term encoding and immunodetection stability and could be quickly magnetically separated and enriched. Then, the QD-encoded magnetic microbeads were applied to alpha fetoprotein (AFP) detection via sandwich immunoreaction. The properties of the encoded microspheres were characterized using a self-designed detecting apparatus, and the target molecular concentration in the sample was also quantified. The results suggested that the high-performance FEMMs have great potential in the field of biomolecular detection. - Graphical abstract: We designed a novel strategy to prepare a kind of high-performance fluorescence-encoded magnetic microbeads as microfluidic protein chip support with long-time fluorescent encoding and immunodetection stability for AFP detection. - Highlights: • A novel strategy combined the high temperature with chemical swelling technology is designed. • Based on hydrophobic interaction and polymer thermal motion, QDs and Fe{sub 3}O{sub 4} were effectively packaged into microbeads. • The fluorescence-encoded magnetic microbeads show long-term fluorescent encoding and immunodetection stability.

  8. Ratiometric fluorescent nanosensor based on carbon dots for the detection of mercury ion

    Science.gov (United States)

    Ma, Yusha; Mei, Jing; Bai, Jianliang; Chen, Xu; Ren, Lili

    2018-05-01

    A novel ratiometric fluorescent nanosensor based on carbon dots has been synthesized via bonding rhodamine B hydrazide to the carbon dots surface by an amide reaction. The ratiometric fluorescent nanosensor showed only a single blue fluorescence emission around 450 nm. While, as mercury ion was added, due to the open-ring of rhodamine moiety bonded on the CDs surface, the orange emission of the open-ring rhodamine would increase obviously according to the concentration of mercury ion, resulting in the distinguishable dual emissions at 450 nm and 575 nm under a single 360 excitation wavelength. Meanwhile, the ratiometric fluorescent nanosensor based on carbon dots we prepared is more sensitive to qualitative and semi-quantitative detection of mercury ion in the range of 0–100 μM, because fluorescence changes gradually from blue to orange emission under 365 nm lamp with the increasing of mercury ion in the tested solution.

  9. Combining electrophoresis with detection under ultraviolet light and multiple ultrafiltration for isolation of humic fluorescence fractions.

    Science.gov (United States)

    Trubetskaya, Olga E; Shaloiko, Lubov A; Demin, Dmitrii V; Marchenkov, Victor V; Proskuryakov, Ivan I; Coelho, Christian; Trubetskoj, Oleg A

    2011-04-01

    Polyacrylamide gel electrophoresis of chernozem soil humic acids (HAs) followed by observation under UV (312 nm) excitation light reveals new low molecular weight (MW) fluorescent fractions. Ultrafiltration of HAs sample in 7 M urea on a membrane of low nominal MW retention (NMWR, 5 kDa) was repetitively used for separation of fluorescent and non-fluorescent species. Thirty ultrafiltrates and the final retentate R were obtained. Fluorescence maxima of separate ultrafiltrates were different and non-monotonously changed in the range of 475-505 nm. Fluorescence maxima of less than 490 nm were detected only in the four first utrafiltrates. For further physical-chemical analyses all utrafiltrates were combined into a fraction called UFchernozem soil HAs complex. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Enhancing early bladder cancer detection with fluorescence-guided endoscopic optical coherence tomography

    Science.gov (United States)

    Pan, Y. T.; Xie, T. Q.; Du, C. W.; Bastacky, S.; Meyers, S.; Zeidel, M. L.

    2003-12-01

    We report an experimental study of the possibility of enhancing early bladder cancer diagnosis with fluorescence-image-guided endoscopic optical coherence tomography (OCT). After the intravesical instillation of a 10% solution of 5-aminolevulinic acid, simultaneous fluorescence imaging (excitation of 380-420 nm, emission of 620-700 nm) and OCT are performed on rat bladders to identify the photochemical and morphological changes associated with uroepithelial tumorigenesis. The preliminary results of our ex vivo study reveal that both fluorescence and OCT can identify early uroepithelial cancers, and OCT can detect precancerous lesions (e.g., hyperplasia) that fluorescence may miss. This suggests that a cystoscope combining 5-aminolevulinic acid fluorescence and OCT imaging has the potential to enhance the efficiency and sensitivity of early bladder cancer diagnosis.

  11. A fluorescent optical fibre chemosensor for mercury detection

    Science.gov (United States)

    Wren, Stephen P.; Sun, Tong; Grattan, Kenneth T. V.

    2015-09-01

    A proof-of-concept mercury probe was developed based on covalent attachment of a chemical coating to optical fibre. The sensing element comprised a dansyl derivative and crown ether moiety, acting as fluorophore and metal ion chelator respectively. An ON-OFF type fluorescence (quench) occurred upon binding of mercury ions, via an intramolecular charge transfer mechanism, in aqueous solution in the 909nM-90.9μM (247 ppb -24.7 ppm) concentration range. A washing protocol was identified for sensor regeneration allowing the probe to be re-used.

  12. Fluorescent detection of C-reactive protein using polyamide beads

    Science.gov (United States)

    Jagadeesh, Shreesha; Chen, Lu; Aitchison, Stewart

    2016-03-01

    Bacterial infection causes Sepsis which is one of the leading cause of mortality in hospitals. This infection can be quantified from blood plasma using C - reactive protein (CRP). A quick diagnosis at the patient's location through Point-of- Care (POC) testing could give doctors the confidence to prescribe antibiotics. In this paper, the development and testing of a bead-based procedure for CRP quantification is described. The size of the beads enable them to be trapped in wells without the need for magnetic methods of immobilization. Large (1.5 mm diameter) Polyamide nylon beads were used as the substrate for capturing CRP from pure analyte samples. The beads captured CRP either directly through adsorption or indirectly by having specific capture antibodies on their surface. Both methods used fluorescent imaging techniques to quantify the protein. The amount of CRP needed to give a sufficient fluorescent signal through direct capture method was found suitable for identifying bacterial causes of infection. Similarly, viral infections could be quantified by the more sensitive indirect capture method. This bead-based assay can be potentially integrated as a disposable cartridge in a POC device due to its passive nature and the small quantities needed.

  13. A benzothiazole-based fluorescent probe for hypochlorous acid detection and imaging in living cells

    Science.gov (United States)

    Nguyen, Khac Hong; Hao, Yuanqiang; Zeng, Ke; Fan, Shengnan; Li, Fen; Yuan, Suke; Ding, Xuejing; Xu, Maotian; Liu, You-Nian

    2018-06-01

    A benzothiazole-based turn-on fluorescent probe with a large Stokes shift (190 nm) has been developed for hypochlorous acid detection. The probe displays prompt fluorescence response for HClO with excellent selectivity over other reactive oxygen species as well as a low detection limit of 0.08 μM. The sensing mechanism involves the HClO-induced specific oxidation of oxime moiety of the probe to nitrile oxide, which was confirmed by HPLC-MS technique. Furthermore, imaging studies demonstrated that the probe is cell permeable and can be applied to detect HClO in living cells.

  14. A turn-on fluorescent rhodamine-acyl hydrazide for selective detection of Cu"2"+ ions

    International Nuclear Information System (INIS)

    Yoon, Jung Won; Jeong, Hyuk; Lee, Min Hee

    2017-01-01

    We present a rhodamine-based probe that can detect Cu"2"+ ions via Cu"2"+-promoted hydrolysis in aqueous solutions. In solution, the probe is non-fluorescent and colorless, but gives a strong fluorescence at 586 nm and shows a color change to pink on the addition of Cu"2"+ ions. We demonstrate that the rhodamine-based probe undergoes Cu"2"+-promoted hydrolysis with a moderate reaction time (within 3 min) and provides a fluorescence off–on change, even in the presence of other competitive metal ions. The rhodamine-based probe shows a linear correlation between increasing fluorescence at 586 nm and the Cu"2"+ concentration, and can detect Cu"2"+ at nanomolar levels (10 nM) in CH_3CN:H_2O (v/v, 90:10)

  15. Early detection of tumor masses by in vivo hematoporphyrin-mediated fluorescence imaging

    International Nuclear Information System (INIS)

    Autiero, Maddalena; Celentano, Luigi; Cozzolino, Rosanna; Laccetti, Paolo; Marotta, Marcello; Mettivier, Giovanni; Cristina Montesi, Maria; Quarto, Maria; Riccio, Patrizia; Roberti, Giuseppe; Russo, Paolo

    2007-01-01

    We investigated the capability of fluorescence reflectance imaging (FRI) for the early detection of surface tumors in mice. We used a hematoporphyrin (HP) compound (HP dichlorohydrate) as a red fluorescent marker and a low noise, high sensitivity, digital CCD camera for fluorescence imaging. In this preliminary study, highly malignant anaplastic human thyroid carcinoma cells were implanted subcutaneously in one mouse and their growth was monitored daily for 5 days by FRI. The selective HP uptake by the tumor tissues was successfully observed: we observed the fluorescence of tumor only 3 days after cancer cells injection, i.e. when the tumor mass was neither visible (to the naked eye) or palpable. These measurements indicate that FRI is a suitable technique to detect minute subcutaneous tumor masses. This FRI system will be coupled to a radionuclide imaging system based on a CdTe detector for in vivo multimodal imaging in mice

  16. Interpenetrated Binary Supramolecular Nanofibers for Sensitive Fluorescence Detection of Six Classes of Explosives.

    Science.gov (United States)

    Xiong, Wei; Zhu, Qijian; Gong, Yanjun; Wang, Chen; Che, Yanke; Zhao, Jincai

    2018-04-03

    In this work, we develop a sequential self-assembly approach to fabricate interpenetrated binary supramolecular nanofibers consisting of carbazole oligomer 1-cobalt(II) (1-Co 2+ ) coordination nanofibers and oligomer 2 nanofibers for the sensitive detection of six classes of explosives. When exposed to peroxide explosives (e.g., H 2 O 2 ), Co 2+ in 1-Co 2+ coordination nanofibers can be reduced to Co + that can transfer an electron to the excited 2 nanofibers and thereby quench their fluorescence. On the other hand, when exposed to the other five classes of explosives, the excited 2 nanofibers can transfer an electron to explosives to quench their fluorescence. On the basis of the distinct fluorescence quenching mechanisms, six classes of explosives can be sensitively detected. Herein, we provide a new strategy to design broad-band fluorescence sensors for a rich identification of threats.

  17. Improvement of the qualitative and quantitative detection of simultaneously present fluorescent tracers by systematic sample treatment

    International Nuclear Information System (INIS)

    Behrens, H.

    1982-01-01

    The selective instrumental detection of individual fluorescent tracers in mixtures containing further fluorescent dyes is limited by spectral interferences. Therefore additional separations or other suitable procedures have to be included into the analytic technique. With the method described below, the respective tracer to be detected remains with its initial concentration in the sample and is analysed under the appropriate conditions, whereas the interfering tracers are separated or suppressed. The techniques applied for this base on the facts that 1) the fluorescence intensity of the tracers varies differently when the pH-value changes; 2) the tracers show different absorption behaviour and 3) they provide different degrees of light sensitivity. The procedures permit for example to detect uranin when eosin is present in a higher concentration or to detect eosin when amidorhodamin G is present. (orig.) [de

  18. Sentinel lymph nodes fluorescence detection and imaging using Patent Blue V bound to human serum albumin

    Science.gov (United States)

    Tellier, Franklin; Steibel, Jérôme; Chabrier, Renée; Blé, François Xavier; Tubaldo, Hervé; Rasata, Ravelo; Chambron, Jacques; Duportail, Guy; Simon, Hervé; Rodier, Jean-François; Poulet, Patrick

    2012-01-01

    Patent Blue V (PBV), a dye used clinically for sentinel lymph node detection, was mixed with human serum albumin (HSA). After binding to HSA, the fluorescence quantum yield increased from 5 × 10−4 to 1.7 × 10−2, which was enough to allow fluorescence detection and imaging of its distribution. A detection threshold, evaluated in scattering test objects, lower than 2.5 nmol × L−1 was obtained, using a single-probe setup with a 5-mW incident light power. The detection sensitivity using a fluorescence imaging device was in the µmol × L−1 range, with a noncooled CCD camera. Preclinical evaluation was performed on a rat model and permitted to observe inflamed nodes on all animals. PMID:23024922

  19. Fluorescence hyperspectral imaging technique for the foreign substance detection on fresh-cut lettuce

    Science.gov (United States)

    Nondestructive methods based on fluorescence hyperspectral imaging (HSI) techniques were developed in order to detect worms on fresh-cut lettuce. The optimal wavebands for detecting worms on fresh-cut lettuce were investigated using the one-way ANOVA analysis and correlation analysis. The worm detec...

  20. Micromotor-based on-off fluorescence detection of sarin and soman simulants.

    Science.gov (United States)

    Singh, Virendra V; Kaufmann, Kevin; Orozco, Jahir; Li, Jinxing; Galarnyk, Michael; Arya, Gaurav; Wang, Joseph

    2015-06-30

    Self-propelled micromotor-based fluorescent "On-Off" detection of nerve agents is described. The motion-based assay utilizes Si/Pt Janus micromotors coated with fluoresceinamine toward real-time "on-the-fly" field detection of sarin and soman simulants.

  1. Determination of acetylsalicylic acid and salicylic acid in foods, using HPLC with fluorescence detection.

    NARCIS (Netherlands)

    Venema, D.P.; Hollman, P.C.H.; Janssen, P.L.T.M.K.; Katan, M.B.

    1996-01-01

    We developed a specific and sensitive HPLC method with fluorescence detection for the determination of free acetylsalicylic acid, free salicylic acid, and free salicylic acid plus salicylic acid after alkaline hydrolysis (free-plus-bound) in foods. Acetylsalicylic acid was detected after postcolumn

  2. Electrophoresis microchip with integrated waveguides for simultaneous native UV fluorescence and absorbance detection

    DEFF Research Database (Denmark)

    Ohlsson, Pelle Daniel; Sala, Olga Ordeig; Mogensen, Klaus Bo

    2009-01-01

    Simultaneous label-free detection of UV absorbance and native UV-excited fluorescence in an electrophoresis microchip is presented. UV transparent integrated waveguides launch light at a wavelength of 254 nm from a mercury lamp along the length of a 1-mm. long detection cell. Transmitted UV light...

  3. Detecting Kerogen as a Biosignature Using Colocated UV Time-Gated Raman and Fluorescence Spectroscopy.

    Science.gov (United States)

    Shkolyar, Svetlana; Eshelman, Evan J; Farmer, Jack D; Hamilton, David; Daly, Michael G; Youngbull, Cody

    2018-04-01

    The Mars 2020 mission will analyze samples in situ and identify any that could have preserved biosignatures in ancient habitable environments for later return to Earth. Highest priority targeted samples include aqueously formed sedimentary lithologies. On Earth, such lithologies can contain fossil biosignatures as aromatic carbon (kerogen). In this study, we analyzed nonextracted kerogen in a diverse suite of natural, complex samples using colocated UV excitation (266 nm) time-gated (UV-TG) Raman and laser-induced fluorescence spectroscopies. We interrogated kerogen and its host matrix in samples to (1) explore the capabilities of UV-TG Raman and fluorescence spectroscopies for detecting kerogen in high-priority targets in the search for possible biosignatures on Mars; (2) assess the effectiveness of time gating and UV laser wavelength in reducing fluorescence in Raman spectra; and (3) identify sample-specific issues that could challenge rover-based identifications of kerogen using UV-TG Raman spectroscopy. We found that ungated UV Raman spectroscopy is suited to identify diagnostic kerogen Raman bands without interfering fluorescence and that UV fluorescence spectroscopy is suited to identify kerogen. These results highlight the value of combining colocated Raman and fluorescence spectroscopies, similar to those obtainable by SHERLOC on Mars 2020, to strengthen the confidence of kerogen detection as a potential biosignature in complex natural samples. Key Words: Raman spectroscopy-Laser-induced fluorescence spectroscopy-Mars Sample Return-Mars 2020 mission-Kerogen-Biosignatures. Astrobiology 18, 431-453.

  4. Highly selective ratiometric fluorescent detection of Fe{sup 3+} with a polyphenyl derivative

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhan-Xian, E-mail: lizx@zzu.edu.cn [The College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhou, Wan; Zhang, Li-Feng; Yuan, Rui-Li; Liu, Xing-Jiang; Wei, Liu-He [The College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Yu, Ming-Ming, E-mail: yumm@zzu.edu.cn [The College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China)

    2013-04-15

    Compared with other fluorescent probes, ratiometric fluorescence responses are more attractive because the ratio between the two emission intensities can be used to measure the analyte concentration and provide a built-in correction for environmental effects. A highly selective and sensitive ratiometric fluorescent probe for Fe{sup 3+} was synthesized, which exhibits an enhanced fluorescence with a large red-shift in emission from 361 to 455 nm upon addition of Fe{sup 3+}. The red-shift of the emission peak can be ascribed to the reformed orbital, and the increase of emission intensity may be ascribed to the inhibition of the rotation of C–C bonds between each two aromatic rings. -- Graphical abstract: A highly selective and sensitive ratiometric fluorescent probe for Fe{sup 3+} was synthesized, which exhibits an enhanced fluorescence with a large red-shift in emission from 361 to 455 nm upon addition of Fe{sup 3+}. Highlights: ► A ratiometric fluorescent probe for Fe{sup 3+} was synthesized. ► The probe exhibits an enhanced fluorescence with a red-shift upon addition of Fe{sup 3+}. ► Inhibition of the rotation of C–C bonds was possible detection mechanism for Fe{sup 3+}.

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

    Science.gov (United States)

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

    2005-01-01

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

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

    Science.gov (United States)

    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. Copyright © 2016. Published by Elsevier B.V.

  7. Ultra-sensitive and selective Hg{sup 2+} detection based on fluorescent carbon dots

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ruihua; Li, Haitao; Kong, Weiqian; Liu, Juan [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Tong, Cuiyan, E-mail: tongcy959@nenu.edu.cn [Chemisty Department, Northeast Normal University, Changchun 130024 (China); Zhang, Xing [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)

    2013-07-15

    Graphical abstract: Fluorescent carbon dots were efficiently synthesized by one-step sodium hydroxide-assisted reflux method from PEG and demonstrated to show high selectivity toward Hg2+ ions detection. - Highlights: • FCDs were synthesized by one-step sodium hydroxide-assisted reflux method from PEG. • The FCDs emit blue photoluminescence and have upconversion fluorescent property. • The FCDs show ultra-sensitive detective ability for Hg{sup 2+} ions. - Abstract: Fluorescent carbon dots (FCDs) were efficiently synthesized by one-step sodium hydroxide-assisted reflux method from poly(ethylene glycol) (PEG). The obtained FCDs exhibit excellent water-solubility and high stability. Under the UV irradiation, the FCDs could emit bright blue photoluminescence, and also they were found to show excellent up-conversion fluorescence. It was further demonstrated that such FCDs can serve as effective fluorescent sensing platform for Hg{sup 2+} ions detection with ultra-sensitivity and selectivity. The sensing system achieved a limit of detection as low as 1 fM, which is much lower than all the previous reported sensing systems for Hg{sup 2+} ions detection. This FCDs sensing system has been successfully applied for the analysis of Hg{sup 2+} ions in water samples from river, lake, and tap water, showing good practical feasibility.

  8. Bioconjugated fluorescent silica nanoparticles for the rapid detection of Entamoeba histolytica.

    Science.gov (United States)

    Hemadi, Ahmad; Ekrami, Alireza; Oormazdi, Hormozd; Meamar, Ahmad Reza; Akhlaghi, Lame; Samarbaf-Zadeh, Ali Reza; Razmjou, Elham

    2015-05-01

    Rapid detection of Entamoeba histolytica based on fluorescent silica nanoparticle (FSNP) indirect immunofluorescence microscopy was evaluated. Silica nanoparticles were synthesized using Stöber's method, with their surface activated to covalently bind to, and immobilize, protein A. For biolabeling, FSNP was added to conjugated E. histolytica trophozoites with monoclonal anti-E. histolytica IgG1 for microscopic observation of fluorescence. Fluorescent silica nanoparticle sensitivity was determined with axenically cultured E. histolytica serially diluted to seven concentrations. Specificity was evaluated using other intestinal protozoa. Fluorescent silica nanoparticles detected E. histolytica at the lowest tested concentration with no cross-reaction with Entamoeba dispar, Entamoeba moshkovskii, Blastocystis sp., or Giardia lamblia. Visualization of E. histolytica trophozoites with anti-E. histolytica antibody labeled with fluorescein isothiocyanate (FITC) was compared with that using anti-E. histolytica antibody bioconjugated FSNP. Although FITC and FSNP produced similar results, the amount of specific antibody required for FITC to induce fluorescence of similar intensity was fivefold that for FSNP. Fluorescent silica nanoparticles delivered a rapid, simple, cost-effective, and highly sensitive and specific method of detecting E. histolytica. Further study is needed before introducing FSNP for laboratory diagnosis of amoebiasis. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Highly selective detection of glutathione using a NIP/Cu2+ complex fluorescent probe

    International Nuclear Information System (INIS)

    Liang Wenrui; Zhao Zhi; Zhang Yang; Wang Qiusheng; Zhao Xin; Ouyang Jie

    2012-01-01

    A novel fluorescent compound, 4-(trimethyl ammonium chloride)acetamide-2-(1H-naphtho[2,3-d]imidazol-2-yl)phenol (TMACA-NIP), was synthesized and used as a fluorescent probe for detecting glutathione reduced (GSH). The new NIP-based probe exhibited high fluorescence in water, which was quenched during the presence of copper (II) due to the complexation between TMACA-NIP and Cu 2+ . But after adding GSH into the TMACA-NIP and Cu 2+ system, the fluorescence of TMACA-NIP was recovered because the binding force between GSH and Cu 2+ is stronger than that between TMACA-NIP and Cu 2+ , which destroys the equilibrium between NIP and copper (II) ions and releases the fluorescence probe of TMACA-NIP. This three-component competing system of NIP/Cu 2+ /GSH can be used to detect GSH simply and rapidly. - Highlights: ► A novel fluorescence probe was developed to detect GSH that operates in aqueous solution. ► TMACA-NIP was synthesized and employed as “read-out” units of NIP/Cu 2+ /GSH. ► NIP-based probe shows high selectivity over other sulfhydryl compounds.

  11. Molecular Detection of Bladder Cancer by Fluorescence Microsatellite Analysis and an Automated Genetic Analyzing System

    Directory of Open Access Journals (Sweden)

    Sarel Halachmi

    2007-01-01

    Full Text Available To investigate the ability of an automated fluorescent analyzing system to detect microsatellite alterations, in patients with bladder cancer. We investigated 11 with pathology proven bladder Transitional Cell Carcinoma (TCC for microsatellite alterations in blood, urine, and tumor biopsies. DNA was prepared by standard methods from blood, urine and resected tumor specimens, and was used for microsatellite analysis. After the primers were fluorescent labeled, amplification of the DNA was performed with PCR. The PCR products were placed into the automated genetic analyser (ABI Prism 310, Perkin Elmer, USA and were subjected to fluorescent scanning with argon ion laser beams. The fluorescent signal intensity measured by the genetic analyzer measured the product size in terms of base pairs. We found loss of heterozygocity (LOH or microsatellite alterations (a loss or gain of nucleotides, which alter the original normal locus size in all the patients by using fluorescent microsatellite analysis and an automated analyzing system. In each case the genetic changes found in urine samples were identical to those found in the resected tumor sample. The studies demonstrated the ability to detect bladder tumor non-invasively by fluorescent microsatellite analysis of urine samples. Our study supports the worldwide trend for the search of non-invasive methods to detect bladder cancer. We have overcome major obstacles that prevented the clinical use of an experimental system. With our new tested system microsatellite analysis can be done cheaper, faster, easier and with higher scientific accuracy.

  12. Discriminative detection of bivalent Cu by dual-emission ZnSe quantum dot fluorescence sensing via ratiometric fluorescence measurements

    International Nuclear Information System (INIS)

    Wang, Chunlei; Zhou, Shujie; Xu, Shuhong; Wang, Zhuyuan; Cui, Yiping

    2014-01-01

    In this work, we showed that 1-thioglycerol (TG)-capped ZnSe quantum dots (QDs) with dual-emission could perform ideal QD fluorescence sensing for ratiometric fluorescence measurements. By comparing the fluorescence ratios at two emission peaks before and after the addition of cations, the discriminative detection of Cu(II) was realized, even in the case of co-existing with large amounts of other sensitive cations, such as Ag(I). The discriminative detection of Cu(II) is accurate with co-existing Ag(I) below 10 μmol L −1 . By a joint investigation of the ionic diffuse dynamics and carrier recombination dynamics, we found that the adsorbed layer of QDs plays a key role in the discriminative detection of Cu(II) from Ag(I) or other sensitive cations. The moderate adsorption capacity with a QD adsorbed layer makes Cu(II) capable of travelling across the QD double-layer structure, following a surface doping process via chemical reactions between Cu(II) and the QD surface atoms. As a result of Cu(II) doping, there were three major carrier recombination channels: the non-radiation recombination between the QD conduction band to the Cu(II) energy level, together with the non-radiation recombination and radiation recombination between the trap state energy levels and the Cu(II) energy level. As for Ag(I) and other sensitive cations, they have a strong adsorption capacity with the QD adsorbed layer, making them mainly present on the adsorbed layer. Due to the blocking of the ligand layer, we only observed weak coupling of the ZnSe conduction band with the Ag(I) energy level via a non-radiation recombination channel. (paper)

  13. Fluorescence ELISA for sensitive detection of ochratoxin A based on glucose oxidase-mediated fluorescence quenching of CdTe QDs

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yi [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang 330047 (China); Huang, Xiaolin [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Yu, Ruijin [College of Science, Northwest A& F University, Yangling, Shaanxi 712100 (China); Zhou, Yaofeng [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Xiong, Yonghua, E-mail: yhxiongchen@163.com [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang 330047 (China)

    2016-09-14

    The present study described a novel fluorescence enzyme-linked immunosorbent assay (ELISA) used to detect ochratoxin A (OTA) by using the glucose oxidase (GOx)-mediated fluorescence quenching of mercaptopropionic acid-capped CdTe quantum dots (MPA-QDs), in which GOx was used as an alternative to horseradish peroxidase (HRP) for the oxidization of glucose into hydrogen peroxide (H{sub 2}O{sub 2}) and gluconic acid. The MPA-QDs were used as a fluorescent signal output, whose fluorescence variation was extremely sensitive to the presence of H{sub 2}O{sub 2} or hydrogen ions in the solution. Under the optimized conditions, the proposed fluorescence ELISA demonstrated a good linear detection of OTA in corn extract from 2.4 pg mL{sup −1} to 625 pg mL{sup −1} with a limit of detection of 2.2 pg mL{sup −1}, which was approximately 15-fold lower than that of conventional HRP-based ELISA. Our developed fluorescence immunoassay was also similar to HRP-based ELISA in terms of selectivity, accuracy, and reproducibility. In summary, this study was the first to use the GOx-mediated fluorescence quenching of QDs in immunoassay to detect OTA, offering a new possibility for the analysis of other mycotoxins and biomolecules. - Highlights: • A novel fluorescence ELISA was first developed for the detection of OTA by using GOx-mediated fluorescence quenching of QDs. • The pH- and H{sub 2}O{sub 2}-sensitive MPA-capped CdTe QDs were used as a fluorescent signal output to improve the detection sensitivity. • This novel method open up a different vision to detect other mycotoxins and biomolecules.

  14. Fluorescence ELISA for sensitive detection of ochratoxin A based on glucose oxidase-mediated fluorescence quenching of CdTe QDs

    International Nuclear Information System (INIS)

    Liang, Yi; Huang, Xiaolin; Yu, Ruijin; Zhou, Yaofeng; Xiong, Yonghua

    2016-01-01

    The present study described a novel fluorescence enzyme-linked immunosorbent assay (ELISA) used to detect ochratoxin A (OTA) by using the glucose oxidase (GOx)-mediated fluorescence quenching of mercaptopropionic acid-capped CdTe quantum dots (MPA-QDs), in which GOx was used as an alternative to horseradish peroxidase (HRP) for the oxidization of glucose into hydrogen peroxide (H_2O_2) and gluconic acid. The MPA-QDs were used as a fluorescent signal output, whose fluorescence variation was extremely sensitive to the presence of H_2O_2 or hydrogen ions in the solution. Under the optimized conditions, the proposed fluorescence ELISA demonstrated a good linear detection of OTA in corn extract from 2.4 pg mL"−"1 to 625 pg mL"−"1 with a limit of detection of 2.2 pg mL"−"1, which was approximately 15-fold lower than that of conventional HRP-based ELISA. Our developed fluorescence immunoassay was also similar to HRP-based ELISA in terms of selectivity, accuracy, and reproducibility. In summary, this study was the first to use the GOx-mediated fluorescence quenching of QDs in immunoassay to detect OTA, offering a new possibility for the analysis of other mycotoxins and biomolecules. - Highlights: • A novel fluorescence ELISA was first developed for the detection of OTA by using GOx-mediated fluorescence quenching of QDs. • The pH- and H_2O_2-sensitive MPA-capped CdTe QDs were used as a fluorescent signal output to improve the detection sensitivity. • This novel method open up a different vision to detect other mycotoxins and biomolecules.

  15. Rapid and sensitive detection of ketamine in blood using novel fluorescence genosensor.

    Science.gov (United States)

    Ding, Yanjun; Li, Xingmei; Guo, Yadong; Yan, Jie; Ling, Jiang; Li, Weichen; Lan, Lingmei; Chang, Yunfeng; Cai, Jifeng; Zha, Lagabaiyla

    2017-12-01

    In recent years, drug abuse has been considered as a most challenging social problem that aroused public attention. Ketamine has increased in unregulated use as a 'recreational drug' in teenagers. However, there is no suitable and maneuverable detection method for ketamine in situ at the moment. Fluorescence sensor technique, with predominant recognition and simple operation, is a good potential application in drug detection. Here, we first reported a highly sensitive and selective fluorescence genosensor for rapid detection of ketamine based on DNA-templated silver nanoclusters (DNA-AgNCs) probes, in which the DNA sequence could specially recognize ketamine with high affinity. Parameters affecting detection efficiency were investigated and optimized. Under optimum conditions, the as-prepared genosensor can allow for the determination of ketamine in the concentration range of 0.0001-20 μg/mL with two linear equations: one is y = 2.84x-7.139 (R 2 = 0.987) for 0.0001-0.1 μg/mL, and the other is y = 1.87x-0.091 (R 2 = 0.962) for 0.1-20 μg/mL, and the estimated detection limit of ketamine is 0.06 ng/mL. Moreover, the feasibility of this proposed method was also demonstrated by analyzing forensic blood samples. Compared with official gas chromatography/mass spectrometry (GC/MS), this fluorescence genosensor is simple, rapid, and accurate for quantitative determination of ketamine in blood for pharmaceutical and forensic analysis. Overall, it is the first report on a fluorescence genosensor for detecting ketamine directly in blood. This research may provide a new insight for the analyst to band fluorescence genosensor technology together with drug monitoring in the battle against drug abuse and forensic examination. Graphical abstract High selectively detection of ketamine using a novel fluorescence genosensor based on DNA-AgNCs probe.

  16. Detection of bacterial infection of agave plants by laser-induced fluorescence

    Science.gov (United States)

    Cervantes-Martinez, Jesus; Flores-Hernandez, Ricardo; Rodriguez-Garay, Benjamin; Santacruz-Ruvalcaba, Fernando

    2002-05-01

    Greenhouse-grown plants of Agave tequilana Weber var. azul were inoculated with Erwinia carotovora, the causal agent of stem soft rot. We investigated the laser-induced fluorescence (LIF) of agave plants to determine whether LIF can be used as a noninvasive sensing tool for pathological studies. The LIF technique was also investigated as a means of detecting the effect of the polyamine biosynthesis inhibitor beta-hydroxyethylhydrazine as a bactericide against the pathogenic bacterium Erwinia carotovora. A He-Ne laser at 632.8 nm was used as the excitation source, and in vivo fluorescence emission spectra were recorded in the 660-790-range. Fluorescence maxima were at 690 and 740 nm. The infected plants that were untreated with the bactericide showed a definite increase in fluorescence intensity at both maxima within the first three days after infection. Beginning on the fifth day, a steady decrease in fluorescence intensity was observed, with a greater effect at 740 than at 690 nm. After 30 days there was no fluorescence. The infected plants that had been treated with the bactericide showed no significant change in fluorescence compared with that of the uninfected plants. The ratio of fluorescence intensities was determined to be F 690 nm/F 740 nm for all treatments. These studies indicate that LIF measurements of agave plants may be used for the early detection of certain types of disease and for determining the effect of a bactericide on bacteria. The results also showed that fluorescence intensity ratios can be used as a reliable indicator of the progress of disease.

  17. Fiber optic fluorescence detection of low-level porphyrin concentrations in preclinical and clinical studies

    Science.gov (United States)

    Mang, Thomas S.; McGinnis, Carolyn; Khan, S.

    1990-07-01

    A significant clinical problem in the local treatment of cutaneous metastases of breast cancer (by any modality--surgery, radiation therapy or photodynainic therapy) is the fact that the disease almost always extends beyond the boundary of visible lesions in the form of microscopic deposits. These deposits may be distant from the site of visible disease but are often in close proximity to it and are manifested sooner or later by the development of recurrent lesions at the border of the treated area, thus the "marginal miss" in radiation therapy, the "rim recurrence" in photodynamic therapy, and the "incisional recurrence" following surgical excision. More intelligent use of these treatment modalities demands the ability to detect microscopic deposits of tumor cells using non-invasive methodology. In vivo fluorescence measurements have been made possible by the development of an extremely sensitive fiber optic in vivo fluorescence photometer. The instrument has been used to verify that fluorescence correlated with injected porphyrin levels in various tissues. The delivery of light to excite and detect background fluorescence as well as photosensitizer fluorescence in tissues has been accomplished using two HeNe lasers emitting at 632.8 nm and 612 nm delivered through a single quartz fiber optic. Chopping at different frequencies, contributions of fluorescence may be separated. Fluorescence is picked up via a 400 micron quartz fiber optic positioned appropriately near the target tissue. Validation of these levels was made by extraction of the drug from the tissues with resultant quantitation. Recently, an extensive study was undertaken to determine if fluorescence could be used for the detection of occult, clinically non-palpable metastases in the lymph node of rats. This unique model allowed for the detection of micrometastases in lymph nodes using very low injected doses of the photosensitizer Photofrin II. Data obtained revealed the ability to detect on the order

  18. Hybridization chain reaction amplification for highly sensitive fluorescence detection of DNA with dextran coated microarrays.

    Science.gov (United States)

    Chao, Jie; Li, Zhenhua; Li, Jing; Peng, Hongzhen; Su, Shao; Li, Qian; Zhu, Changfeng; Zuo, Xiaolei; Song, Shiping; Wang, Lianhui; Wang, Lihua

    2016-07-15

    Microarrays of biomolecules hold great promise in the fields of genomics, proteomics, and clinical assays on account of their remarkably parallel and high-throughput assay capability. However, the fluorescence detection used in most conventional DNA microarrays is still limited by sensitivity. In this study, we have demonstrated a novel universal and highly sensitive platform for fluorescent detection of sequence specific DNA at the femtomolar level by combining dextran-coated microarrays with hybridization chain reaction (HCR) signal amplification. Three-dimensional dextran matrix was covalently coated on glass surface as the scaffold to immobilize DNA recognition probes to increase the surface binding capacity and accessibility. DNA nanowire tentacles were formed on the matrix surface for efficient signal amplification by capturing multiple fluorescent molecules in a highly ordered way. By quantifying microscopic fluorescent signals, the synergetic effects of dextran and HCR greatly improved sensitivity of DNA microarrays, with a detection limit of 10fM (1×10(5) molecules). This detection assay could recognize one-base mismatch with fluorescence signals dropped down to ~20%. This cost-effective microarray platform also worked well with samples in serum and thus shows great potential for clinical diagnosis. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Fluorescence turn-on detection of target sequence DNA based on silicon nanodot-mediated quenching.

    Science.gov (United States)

    Zhang, Yanan; Ning, Xinping; Mao, Guobin; Ji, Xinghu; He, Zhike

    2018-05-01

    We have developed a new enzyme-free method for target sequence DNA detection based on the dynamic quenching of fluorescent silicon nanodots (SiNDs) toward Cy5-tagged DNA probe. Fascinatingly, the water-soluble SiNDs can quench the fluorescence of cyanine (Cy5) in Cy5-tagged DNA probe in homogeneous solution, and the fluorescence of Cy5-tagged DNA probe can be restored in the presence of target sequence DNA (the synthetic target miRNA-27a). Based on this phenomenon, a SiND-featured fluorescent sensor has been constructed for "turn-on" detection of the synthetic target miRNA-27a for the first time. This newly developed approach possesses the merits of low cost, simple design, and convenient operation since no enzymatic reaction, toxic reagents, or separation procedures are involved. The established method achieves a detection limit of 0.16 nM, and the relative standard deviation of this method is 9% (1 nM, n = 5). The linear range is 0.5-20 nM, and the recoveries in spiked human fluids are in the range of 90-122%. This protocol provides a new tactic in the development of the nonenzymic miRNA biosensors and opens a promising avenue for early diagnosis of miRNA-associated disease. Graphical abstract The SiND-based fluorescent sensor for detection of S-miR-27a.

  20. A fluorescent sensor for selective detection of cyanide using mesoporous graphitic carbon(IV) nitride.

    Science.gov (United States)

    Lee, Eun Zoo; Lee, Sun Uk; Heo, Nam-Su; Stucky, Galen D; Jun, Young-Si; Hong, Won Hi

    2012-04-25

    A turn-on fluorescence sensor, Cu(2+)-c-mpg-C(3)N(4), was developed for detection of CN(-) in aqueous solution by simply mixing cubic mesoporous graphitic carbon nitride (c-mpg-C(3)N(4)) and aqueous solution of Cu(NO(3))(2). The highly sensitive detection of CN(-) with a detection limit of 80 nM is not only possible in aqueous solution but also in human blood serum.

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

    Science.gov (United States)

    Chen, Qing; Fang, Zhijie

    2018-03-01

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

  2. Fluorescent Silica Nanoparticles in the Detection and Control of the Growth of Pathogen

    International Nuclear Information System (INIS)

    Chitra, K.; Annadurai, G.

    2013-01-01

    In this present study the bio conjugated fluorescent silica nanoparticles give an efficient fluorescent-based immunoassay for the detection of pathogen. The synthesized silica nanoparticles were poly dispersed and the size of the silica nanoparticles was in the range of 114-164 nm. The energy dispersive X-ray spectrophotometer showed the presence of silica at 1.8 keV and the selected area diffractometer showed amorphous nature of silica nanoparticles. The FTIR spectrum confirmed the attachment of dye and carboxyl group onto the silica nanoparticles surface. The fluorescent silica nanoparticles showed highly efficient fluorescence and the fluorescent emission of silica nanoparticles occurred at 536 nm. The SEM image showed the aggregation of nanoparticles and bacteria. The growth of the pathogenic E. coli was controlled using silica nanoparticles; therefore silica nanoparticles could be used in food packaging material, biomedical material, and so forth. This work provides a rapid, simple, and accurate method for the detection of pathogen using fluorescent-based immunoassay.

  3. Rapid and sensitive detection of clenbuterol using a fluorescence nanosensor based on diazo coupling mechanism

    Science.gov (United States)

    Thanh Hop Tran, Thi; Huong Do, Thi Mai; Hoang, Mai Ha; Tuyen Nguyen, Duc; Le, Quang Tuan; Nghia Nguyen, Duc; Ngo, Trinh Tung

    2015-01-01

    In this paper, the fluorescence resonance energy transfer (FRET) effect has been used for fabrication of nanosensor for the detection of clenbuterol. In the nanosensor, the CdTe quantum dots (QDs) are the donors while the acceptor is the super-macromolecule formed by the diazoation coupling mechanism between diazo clenbuterol and naphthylethylene diamine. Changes in fluorescence intensities of nanosensor were used to determine the clenbuterol concentration. We have successfully fabricated a nanosensor for detection of clenbuterol sensible to clenbuterol concentration of 10-12 g ml-1.

  4. Highly Sensitive Fluorescence Probe Based on Functional SBA-15 for Selective Detection of Hg2+

    Directory of Open Access Journals (Sweden)

    Wang Xiaoyu

    2010-01-01

    Full Text Available Abstract An inorganic–organic hybrid fluorescence chemosensor (DA/SBA-15 was prepared by covalent immobilization of a dansylamide derivative into the channels of mesoporous silica material SBA-15 via (3-aminopropyltriethoxysilane (APTES groups. The primary hexagonally ordered mesoporous structure of SBA-15 was preserved after the grafting procedure. Fluorescence characterization shows that the obtained inorganic–organic hybrid composite is highly selective and sensitive to Hg2+ detection, suggesting the possibility for real-time qualitative or quantitative detection of Hg2+ and the convenience for potential application in toxicology and environmental science.

  5. Method for detecting binding events using micro-X-ray fluorescence spectrometry

    Science.gov (United States)

    Warner, Benjamin P.; Havrilla, George J.; Mann, Grace

    2010-12-28

    Method for detecting binding events using micro-X-ray fluorescence spectrometry. Receptors are exposed to at least one potential binder and arrayed on a substrate support. Each member of the array is exposed to X-ray radiation. The magnitude of a detectable X-ray fluorescence signal for at least one element can be used to determine whether a binding event between a binder and a receptor has occurred, and can provide information related to the extent of binding between the binder and receptor.

  6. Detection of Sn(II) ions via quenching of the fluorescence of carbon nanodots

    International Nuclear Information System (INIS)

    Mohd Yazid, S.N.A.; Chin, S.F.; Pang, S.C.; Ng, S.M.

    2013-01-01

    We report that fluorescent carbon nanodots (C-dots) can act as an optical probe for quantifying Sn(II) ions in aqueous solution. C-dots are synthesized by carbonization and surface oxidation of preformed sago starch nanoparticles. Their fluorescence is significantly quenched by Sn(II) ions, and the effect can be used to determine Sn(II) ions. The highest fluorescence intensity is obtained at a concentration of 1.75 mM of C-dots in aqueous solution. The probe is highly selective and hardly interfered by other ions. The quenching mechanism appears to be predominantly of the static (rather than dynamic) type. Under optimum conditions, there is a linear relationship between fluorescence intensity and Sn(II) ions concentration up to 4 mM, and with a detection limit of 0.36 μM. (author)

  7. In vivo fluorescent detection of Fe-S clusters coordinated by human GRX2.

    Science.gov (United States)

    Hoff, Kevin G; Culler, Stephanie J; Nguyen, Peter Q; McGuire, Ryan M; Silberg, Jonathan J; Smolke, Christina D

    2009-12-24

    A major challenge to studying Fe-S cluster biosynthesis in higher eukaryotes is the lack of simple tools for imaging metallocluster binding to proteins. We describe the first fluorescent approach for in vivo detection of 2Fe2S clusters that is based upon the complementation of Venus fluorescent protein fragments via human glutaredoxin 2 (GRX2) coordination of a 2Fe2S cluster. We show that Escherichia coli and mammalian cells expressing Venus fragments fused to GRX2 exhibit greater fluorescence than cells expressing fragments fused to a C37A mutant that cannot coordinate a metallocluster. In addition, we find that maximal fluorescence in the cytosol of mammalian cells requires the iron-sulfur cluster assembly proteins ISCU and NFS1. These findings provide evidence that glutaredoxins can dimerize within mammalian cells through coordination of a 2Fe2S cluster as observed with purified recombinant proteins. Copyright 2009 Elsevier Ltd. All rights reserved.

  8. Metal Nanoparticles/Porous Silicon Microcavity Enhanced Surface Plasmon Resonance Fluorescence for the Detection of DNA

    Directory of Open Access Journals (Sweden)

    Jiajia Wang

    2018-02-01

    Full Text Available A porous silicon microcavity (PSiMC with resonant peak wavelength of 635 nm was fabricated by electrochemical etching. Metal nanoparticles (NPs/PSiMC enhanced fluorescence substrates were prepared by the electrostatic adherence of Au NPs that were distributed in PSiMC. The Au NPs/PSiMC device was used to characterize the target DNA immobilization and hybridization with its complementary DNA sequences marked with Rhodamine red (RRA. Fluorescence enhancement was observed on the Au NPs/PSiMC device substrate; and the minimum detection concentration of DNA ran up to 10 pM. The surface plasmon resonance (SPR of the MC substrate; which is so well-positioned to improve fluorescence enhancement rather the fluorescence enhancement of the high reflection band of the Bragg reflector; would welcome such a highly sensitive in biosensor.

  9. Metal Nanoparticles/Porous Silicon Microcavity Enhanced Surface Plasmon Resonance Fluorescence for the Detection of DNA.

    Science.gov (United States)

    Wang, Jiajia; Jia, Zhenhong

    2018-02-23

    A porous silicon microcavity (PSiMC) with resonant peak wavelength of 635 nm was fabricated by electrochemical etching. Metal nanoparticles (NPs)/PSiMC enhanced fluorescence substrates were prepared by the electrostatic adherence of Au NPs that were distributed in PSiMC. The Au NPs/PSiMC device was used to characterize the target DNA immobilization and hybridization with its complementary DNA sequences marked with Rhodamine red (RRA). Fluorescence enhancement was observed on the Au NPs/PSiMC device substrate; and the minimum detection concentration of DNA ran up to 10 pM. The surface plasmon resonance (SPR) of the MC substrate; which is so well-positioned to improve fluorescence enhancement rather the fluorescence enhancement of the high reflection band of the Bragg reflector; would welcome such a highly sensitive in biosensor.

  10. The detection of melamine base on a turn-on fluorescence of DNA-Ag nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Peisi [Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, Fuzhou University, Fuzhou 350002 (China); State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong (China); Zhan, Yuanjin; Wu, Mei; Guo, Longhua; Lin, Zhenyu [Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, Fuzhou University, Fuzhou 350002 (China); Qiu, Bin, E-mail: summer328cn@163.com [Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, Fuzhou University, Fuzhou 350002 (China); Chen, Guonan [Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, Fuzhou University, Fuzhou 350002 (China); Cai, Zongwei [State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong (China)

    2017-06-15

    A label-free, ultra-sensitive and turn-on fluorescence method to detect melamine has been developed. The strategy uses the DNA-Ag nanoclusters (DNA-AgNCs) as the fluorescence probe. The fluorescence of DNA-AgNCs can be quenched in presence of Hg{sup 2+}. However, When Hg{sup 2+} and melamine were reacted for 15 min at 1000 rmp then introduced into DNA-AgNCs solution, a strong fluorescence recovery could be found. Based on this methodology, the changing fluorescent intensity has a linear relationship with melamine in the range of 0.2 μM to 4 μM (R{sup 2}=0.997). The detection limit down to 0.1 μM was obtained, which is 200 times lower than the melamine safety limit of 20 μM estimated by the US Food and Drug Administration. In addition, we had been successfully applied this method to detect melamine in milk powder and raw milk.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

    In this paper, enhanced fluorescence emissions were firstly investigated based on SnO 2 nanomaterial, and its application in the detection of DNA hybridization was also demonstrated. The microarray of SnO 2 nanomaterial was fabricated by the vapour phase transport method catalyzed by patterned Au nanoparticles on a silicon substrate. A probe DNA was immobilized on the substrate with patterned SnO 2 nanomaterial, respectively, by covalent and non-covalent linking schemes. When a fluorophore labelled target DNA was hybridized with a probe DNA on the substrate, fluorescence emissions were only observed on the surface of SnO 2 nanomaterial, which indicated the property of enhancing fluorescence signals from the SnO 2 nanomaterial. By comparing the different fluorescence images from covalent and non-covalent linking schemes, the covalent method was confirmed to be more effective for immobilizing a probe DNA. With the combined use of SnO 2 nanomaterial and the covalent linking scheme, the target DNA could be detected at a very low concentration of 10 fM. And the stability of SnO 2 nanomaterial under the experimental conditions was also compared with silicon nanowires. The findings strongly suggested that SnO 2 nanomaterial could be extensively applied in detections of biological samples with enhancing fluorescence property and high stability

  12. Tools for the quantitative analysis of sedimentation boundaries detected by fluorescence optical analytical ultracentrifugation.

    Directory of Open Access Journals (Sweden)

    Huaying Zhao

    Full Text Available Fluorescence optical detection in sedimentation velocity analytical ultracentrifugation allows the study of macromolecules at nanomolar concentrations and below. This has significant promise, for example, for the study of systems of high-affinity protein interactions. Here we describe adaptations of the direct boundary modeling analysis approach implemented in the software SEDFIT that were developed to accommodate unique characteristics of the confocal fluorescence detection system. These include spatial gradients of signal intensity due to scanner movements out of the plane of rotation, temporal intensity drifts due to instability of the laser and fluorophores, and masking of the finite excitation and detection cone by the sample holder. In an extensive series of experiments with enhanced green fluorescent protein ranging from low nanomolar to low micromolar concentrations, we show that the experimental data provide sufficient information to determine the parameters required for first-order approximation of the impact of these effects on the recorded data. Systematic deviations of fluorescence optical sedimentation velocity data analyzed using conventional sedimentation models developed for absorbance and interference optics are largely removed after these adaptations, resulting in excellent fits that highlight the high precision of fluorescence sedimentation velocity data, thus allowing a more detailed quantitative interpretation of the signal boundaries that is otherwise not possible for this system.

  13. ISS Ammonia Leak Detection Through X-Ray Fluorescence

    Science.gov (United States)

    Camp, Jordan; Barthelmy, Scott; Skinner, Gerry

    2013-01-01

    Ammonia leaks are a significant concern for the International Space Station (ISS). The ISS has external transport lines that direct liquid ammonia to radiator panels where the ammonia is cooled and then brought back to thermal control units. These transport lines and radiator panels are subject to stress from micrometeorites and temperature variations, and have developed small leaks. The ISS can accommodate these leaks at their present rate, but if the rate increased by a factor of ten, it could potentially deplete the ammonia supply and impact the proper functioning of the ISS thermal control system, causing a serious safety risk. A proposed ISS astrophysics instrument, the Lobster X-Ray Monitor, can be used to detect and localize ISS ammonia leaks. Based on the optical design of the eye of its namesake crustacean, the Lobster detector gives simultaneously large field of view and good position resolution. The leak detection principle is that the nitrogen in the leaking ammonia will be ionized by X-rays from the Sun, and then emit its own characteristic Xray signal. The Lobster instrument, nominally facing zenith for its astrophysics observations, can be periodically pointed towards the ISS radiator panels and some sections of the transport lines to detect and localize the characteristic X-rays from the ammonia leaks. Another possibility is to use the ISS robot arm to grab the Lobster instrument and scan it across the transport lines and radiator panels. In this case the leak detection can be made more sensitive by including a focused 100-microampere electron beam to stimulate X-ray emission from the leaking nitrogen. Laboratory studies have shown that either approach can be used to locate ammonia leaks at the level of 0.1 kg/day, a threshold rate of concern for the ISS. The Lobster instrument uses two main components: (1) a microchannel plate optic (also known as a Lobster optic) that focuses the X-rays and directs them to the focal plane, and (2) a CCD (charge

  14. Fluorescent carbon nanoparticle-based lateral flow biosensor for ultrasensitive detection of DNA.

    Science.gov (United States)

    Takalkar, Sunitha; Baryeh, Kwaku; Liu, Guodong

    2017-12-15

    We report a fluorescent carbon nanoparticle (FCN)-based lateral flow biosensor for ultrasensitive detection of DNA. Fluorescent carbon nanoparticle with a diameter of around 15nm was used as a tag to label a detection DNA probe, which was complementary with the part of target DNA. A capture DNA probe was immobilized on the test zone of the lateral flow biosensor. Sandwich-type hybridization reactions among the FCN-labeled DNA probe, target DNA and capture DNA probe were performed on the lateral flow biosensor. In the presence of target DNA, FCNs were captured on the test zone of the biosensor and the fluorescent intensity of the captured FCNs was measured with a portable fluorescent reader. After systematic optimizations of experimental parameters (the components of running buffers, the concentration of detection DNA probe used in the preparation of FCN-DNA conjugates, the amount of FCN-DNA dispensed on the conjugate pad and the dispensing cycles of the capture DNA probes on the test-zone), the biosensor could detect a minimum concentration of 0.4 fM DNA. This study provides a rapid and low-cost approach for DNA detection with high sensitivity, showing great promise for clinical application and biomedical diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. An integrated fluorescence detection system in poly(dimethylsiloxane) for microfluidic applications.

    Science.gov (United States)

    Chabinyc, M L; Chiu, D T; McDonald, J C; Stroock, A D; Christian, J F; Karger, A M; Whitesides, G M

    2001-09-15

    This paper describes a prototype of an integrated fluorescence detection system that uses a microavalanche photodiode (microAPD) as the photodetector for microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS). The prototype device consisted of a reusable detection system and a disposable microfluidic system that was fabricated using rapid prototyping. The first step of the procedure was the fabrication of microfluidic channels in PDMS and the encapsulation of a multimode optical fiber (100-microm core diameter) in the PDMS; the tip of the fiber was placed next to the side wall of one of the channels. The optical fiber was used to couple light into the microchannel for the excitation of fluorescent analytes. The photodetector, a prototype solid-state microAPD array, was embedded in a thick slab (1 cm) of PDMS. A thin (80 microm) colored polycarbonate filter was placed on the top of the embedded microAPD to absorb scattered excitation light before it reached the detector. The microAPD was placed below the microchannel and orthogonal to the axis of the optical fiber. The close proximity (approximately 200 microm) of the microAPD to the microchannel made it unnecessary to incorporate transfer optics; the pixel size of the microAPD (30 microm) matched the dimensions of the channels (50 microm). A blue light-emitting diode was used for fluorescence excitation. The microAPD was operated in Geiger mode to detect the fluorescence. The detection limit of the prototype (approximately 25 nM) was determined by finding the minimum detectable concentration of a solution of fluorescein. The device was used to detect the separation of a mixture of proteins and small molecules by capillary electrophoresis; the separation illustrated the suitability of this integrated fluorescence detection system for bioanalytical applications.

  16. A novel fluorescent biosensor for adrenaline detection and tyrosinase inhibitor screening.

    Science.gov (United States)

    Liu, Ziping; Liu, Shasha

    2018-04-17

    In this work, a novel simple fluorescent biosensor for the highly sensitive and selective detection of adrenaline was established. Firstly, water-soluble CuInS 2 quantum dots (QDs) capped by L-Cys were synthesized via a hydrothermal synthesis method. Then, the positively charged adrenaline was assembled on the surface of CuInS 2 QDs due to the electrostatic interactions and hydrogen bonding, which led to the formation of adrenaline-CuInS 2 QD (Adr-CuInS 2 QD) electrostatic complexes. Tyrosinase (TYR) can catalyze adrenaline to generate H 2 O 2 , and additionally oxidize the adrenaline to adrenaline quinone. Both the H 2 O 2 and the adrenaline quinone can quench the fluorescence of the CuInS 2 QDs through the electron transfer (ET) process. Thus, the determination of adrenaline could be facilely achieved by taking advantage of the fluorescence "turn off" feature of CuInS 2 QDs. Under the optimum conditions, the fluorescence quenching ratio I f /I f0 (I f and I f0 were the fluorescence intensity of Adr-CuInS 2 QDs in the presence and absence of TYR, respectively) was proportional to the logarithm of adrenaline concentration in the range of 1 × 10 -8 -1 × 10 -4  mol L -1 with the detection limit of 3.6 nmol L -1 . The feasibility of the proposed biosensor in real sample assay was also studied and satisfactory results were obtained. Significantly, the proposed fluorescent biosensor can also be utilized to screen TYR inhibitors. Graphical abstract Schematic illustration of the fluorescent biosensor for adrenaline detection (A) and tyrosinase inhibitor screening (B).

  17. Distributed Sensor Particles for Remote Fluorescence Detection of Trace Analytes: UXO/CW; TOPICAL

    International Nuclear Information System (INIS)

    SINGH, ANUP K.; GUPTA, ALOK; MULCHANDANI, ASHOK; CHEN, WILFRED; BHATIA, RIMPLE B.; SCHOENIGER, JOSEPH S.; ASHLEY, CAROL S.; BRINKER, C. JEFFREY; HANCE, BRADLEY G.; SCHMITT, RANDAL L.; JOHNSON, MARK S.; HARGIS JR. PHILIP J.; SIMONSON, ROBERT J.

    2001-01-01

    This report summarizes the development of sensor particles for remote detection of trace chemical analytes over broad areas, e.g residual trinitrotoluene from buried landmines or other unexploded ordnance (UXO). We also describe the potential of the sensor particle approach for the detection of chemical warfare (CW) agents. The primary goal of this work has been the development of sensor particles that incorporate sample preconcentration, analyte molecular recognition, chemical signal amplification, and fluorescence signal transduction within a ''grain of sand''. Two approaches for particle-based chemical-to-fluorescence signal transduction are described: (1) enzyme-amplified immunoassays using biocompatible inorganic encapsulants, and (2) oxidative quenching of a unique fluorescent polymer by TNT

  18. Development of a dielectrophoresis-assisted surface plasmon resonance fluorescence biosensor for detection of bacteria

    Science.gov (United States)

    Kuroda, Chiaki; Iizuka, Ryota; Ohki, Yoshimichi; Fujimaki, Makoto

    2018-05-01

    To detect biological substances such as bacteria speedily and accurately, a dielectrophoresis-assisted surface plasmon resonance (SPR) fluorescence biosensor is being developed. Using Escherichia coli as a target organism, an appropriate voltage frequency to collect E. coli cells on indium tin oxide quadrupole electrodes by dielectrophoresis is analyzed. Then, E. coli is stained with 4‧,6-diamidino-2-phenylindole (DAPI). To clearly detect fluorescence signals from DAPI-stained E. coli cells, the sensor is optimized so that we can excite SPR on Al electrodes by illuminating 405 nm photons. As a result, the number of fluorescence signals is increased on the electrodes by the application of a low-frequency voltage. This indicates that E. coli cells with a lower permittivity than the surrounding water are collected by negative dielectrophoresis onto the electrodes where the electric field strength is lowest.

  19. Fluorescence correlation spectroscopy: Ultrasensitive detection in clear and turbid media

    Science.gov (United States)

    Tahari, Abdel Kader

    In this work, I describe the development of a simple, inexpensive, and powerful alternative technique to detect and analyze, without enrichment, extremely low concentrations of cells, bacteria, viruses, and protein aggregates in turbid fluids for clinical and biotechnological applications. The anticipated applications of this technique are many. They range from the determination of the somatic cell count in milk for the dairy industry, to the enumeration and characterization of microorganisms in environmental microbiology and the food industry, and to the fast and ultrasensitive detection of protein aggregates for the diagnosis of Alzheimer's and other neurodegenerative diseases in clinical medicine. A prototype instrument has been built and allowed the detection and quantification of particles down to a few per milliliter in short scanning times. It consists of a small microscope that has a horizontal geometry and a mechanical instrument that holds a cylindrical cuvette (1 cm in diameter) with two motors that provide a rotational and a slower vertical inversion motions. The illumination focus is centered about 200 mum from the wall of the cuvette inside the sample. The total volume that is explored is large (˜1ml/min for bright particles). The data is analyzed with a correlation filter program based on particle passage pattern recognition. I will also describe further work on improving the sensitivity of the technique, expanding it for multiple-species discrimination and enumeration, and testing the prototype device in actual clinical and biotechnological applications. The main clinical application of this project seeks to establish conditions and use this new technique to quantify and size-analyze oligomeric complexes of the Alzheimer's disease beta-peptide in cerebrospinal fluid and other body fluids as a molecular biomarker for persons at risk of Alzheimer's disease dementia. The technology could potentially be extended to the diagnosis and therapeutic

  20. CARIES DETECTION WITH LASER FLUORESCENCE DEVICES. LIMITATIONS OF THEIR USE

    Directory of Open Access Journals (Sweden)

    Andreas Spaveras

    2017-03-01

    Data synthesis: DD and DDPen are useful devices for caries detection on the occlusal tooth surfaces. Their main advantages are the very high reproducibility of measurements (>0.90, the ease of handling and the quantification and monitoring capacity. Their main limitations are the relatively low specificity for enamel lesions, the necessity of unstained surfaces and absence of plaque and pastes during measurements and the absence of a universal, clinically functional calibration value (COV. Conclusion: Further studies are required for more reliable data analysis and clinical interpretation of the relevant results.

  1. Multiplexed Detection of Attomoles of Nucleic Acids Using Fluorescent Nanoparticle Counting Platform.

    Science.gov (United States)

    Pei, Xiaojing; Yin, Haoyan; Lai, Tiancheng; Zhang, Junlong; Liu, Feng; Xu, Xiao; Li, Na

    2018-01-16

    The sensitive multiplexed detection of nucleic acids in a single sample by a simple manner is of pivotal importance for the diagnosis and therapy of human diseases. Herein, we constructed an automatic fluorescent nanoparticle (FNP) counting platform with a common fluorescence microscopic imaging setup for nonamplification multiplexed detection of attomoles of nucleic acids. Taking the advantages of the highly bright, multicolor emitting FNPs and magnetic separation, the platform enables sensitive multiplexed detection without the need for extra fluorescent labels. Quantification for multiplex DNAs, multiplex microRNAs (miRNA), as well as a DNA and miRNA mixture was achieved with a similar dynamic range, a limit of detection down to 5 amol (5 μL detection volume), and a 81-115% spike recovery from different biological sample matrices. In particular, the sensitivity for multiplex miRNA is by far among the highest without using amplification or the lock nucleic acid hybridization enhancement strategy. Results regarding miRNA-141 from four different cell lines were agreeable with those of the quantitative reverse transcription polymerase chain reaction. Simultaneous detection of miRNA-141 and miRNA-21 in four different cell lines yielded consistent results with publications, indicating the potential for monitoring multiplex miRNA expression associated with the collaborative regulation of important cellular events. This work expands the rule set of multiplex nucleic acid detection strategies and shows promising potential application in clinical diagnosis.

  2. Peptide-assembled graphene oxide as fluorescent turn-on sensor for ultrasensitive Lipopolysaccharide (Endotoxin detection

    Directory of Open Access Journals (Sweden)

    Seng Koon Lim

    2014-06-01

    Full Text Available Introduction: Lipopolysaccharide (LPS, or endotoxin, a major component in the outer cell membrane of Gram-negative bacteria is a very powerful and toxic inflammatory stimulator, resulting in sepsis or septic shock, a significant medical problem affecting about 700 000 patients and causing 250 000 casualties annually in the United States itself. The detection of LPS is highly importance. However, the currently used enzymatic limulus amebocyte lysate assay is highly susceptible to changes in temperature and pH, interference factors, and requires cumbersome sample preparation. A more cost-effective, sensitive and robust detection method is needed. Objective: To design and develop biosensor for LPS detection by assembling a LPS-binding peptide (as LPS receptor with graphene oxide (GO, as fluorescence quencher. Methods: GO was synthesized using a modified Hummer’s method. A synthetic LPS-binding peptide was designed, fluorescent labelled, and assembled with GO in PBS buffer solution. The fluorescence recovery of the peptide-GO was measured upon addition of LPS from Gram negative bacteria: E. coli, K. pneumoniae, Samonella Thyphosa, P. aeruginosa, as well as living pathogenic bacteria. Specificity tests were conducted with various biological molecules to evaluate the sensing performance. Results & Discussion: Specific binding of LPS with peptide release the peptides from GO, resulting in fluorescence recovery, allowing ultrasensitive detection of LPS with the limit of detection of 130 pM, the most sensitive synthetic LPS sensors to-date. The LPS sensor is highly selective to LPS than other biological species. Conclusion: We developed a peptide-GO assembled fluorescence sensor for ultrasensitive and specific LPS/endotoxin detection. This is the most sensitive synthetic LPS sensor reported in the world.

  3. Improved detection of urothelial carcinoma in situ with hexaminolevulinate fluorescence cystoscopy.

    NARCIS (Netherlands)

    Schmidbauer, J.; Witjes, J.A.; Schmeller, N.; Donat, R.; Susani, M.; Marberger, M.

    2004-01-01

    PURPOSE: In this European multicenter study we compared hexaminolevulinate (HAL) fluorescence cystoscopy and standard white light cystoscopy for the detection of carcinoma in situ (CIS) in patients suspected of having high risk bladder cancer. MATERIALS AND METHODS: This study was a prospective

  4. Detection of Helicobacter pylori in the Gastric Mucosa by Fluorescence In Vivo Hybridization

    DEFF Research Database (Denmark)

    Fontenete, Silvia; Leite, Marina; Figueiredo, Céu

    2017-01-01

    In this chapter, we describe a fluorescence in vivo hybridization (FIVH) protocol, using nucleic acid probes, for the detection of the bacterium Helicobacter pylori in the gastric mucosa of an infected C57BL/6 mouse model. This protocol should be easily extended to other microorganisms not only...

  5. Improved detection of soma location and morphology in fluorescence microscopy images of neurons.

    Science.gov (United States)

    Kayasandik, Cihan Bilge; Labate, Demetrio

    2016-12-01

    Automated detection and segmentation of somas in fluorescent images of neurons is a major goal in quantitative studies of neuronal networks, including applications of high-content-screenings where it is required to quantify multiple morphological properties of neurons. Despite recent advances in image processing targeted to neurobiological applications, existing algorithms of soma detection are often unreliable, especially when processing fluorescence image stacks of neuronal cultures. In this paper, we introduce an innovative algorithm for the detection and extraction of somas in fluorescent images of networks of cultured neurons where somas and other structures exist in the same fluorescent channel. Our method relies on a new geometrical descriptor called Directional Ratio and a collection of multiscale orientable filters to quantify the level of local isotropy in an image. To optimize the application of this approach, we introduce a new construction of multiscale anisotropic filters that is implemented by separable convolution. Extensive numerical experiments using 2D and 3D confocal images show that our automated algorithm reliably detects somas, accurately segments them, and separates contiguous ones. We include a detailed comparison with state-of-the-art existing methods to demonstrate that our algorithm is extremely competitive in terms of accuracy, reliability and computational efficiency. Our algorithm will facilitate the development of automated platforms for high content neuron image processing. A Matlab code is released open-source and freely available to the scientific community. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Detection of Water Contamination Events Using Fluorescence Spectroscopy and Alternating Trilinear Decomposition Algorithm

    Directory of Open Access Journals (Sweden)

    Jie Yu

    2017-01-01

    Full Text Available The method based on conventional index and UV-vision has been widely applied in the field of water quality abnormality detection. This paper presents a qualitative analysis approach to detect the water contamination events with unknown pollutants. Fluorescence spectra were used as water quality monitoring tools, and the detection method of unknown contaminants in water based on alternating trilinear decomposition (ATLD is proposed to analyze the excitation and emission spectra of the samples. The Delaunay triangulation interpolation method was used to make the pretreatment of three-dimensional fluorescence spectra data, in order to estimate the effect of Rayleigh and Raman scattering; ATLD model was applied to establish the model of normal water sample, and the residual matrix was obtained by subtracting the measured matrix from the model matrix; the residual sum of squares obtained from the residual matrix and threshold was used to make qualitative discrimination of test samples and distinguish drinking water samples and organic pollutant samples. The results of the study indicate that ATLD modeling with three-dimensional fluorescence spectra can provide a tool for detecting unknown organic pollutants in water qualitatively. The method based on fluorescence spectra can be complementary to the method based on conventional index and UV-vision.

  7. Red to far-red multispectral fluorescence image fusion for detection of fecal contamination on apples

    Science.gov (United States)

    This research developed a multispectral algorithm derived from hyperspectral line-scan fluorescence imaging under violet/blue LED excitation for detection of fecal contamination on Golden Delicious apples. Using a hyperspectral line-scan imaging system consisting of an EMCCD camera, spectrograph, an...

  8. Determination of ammonium on an integrated microchip with LED-induced fluorescence detection.

    Science.gov (United States)

    Xue, Shuhua; Uchiyama, Katsumi; Li, Hai-Fang

    2012-01-01

    A simply fabricated microfluidic device integrated with a fluorescence detection system has been developed for on-line determination of ammonium in aqueous samples. A 365-nm light-emitting diode (LED) as an excitation source and a minor band pass filter were mounted into a polydimethylsiloxane (PDMS)-based microchip for the purpose of miniaturization of the entire analytical system. The ammonium sample reacted with o-phthaldialdehyde (OPA) on-chip with sodium sulfite as reducing reagent to produce a fluorescent isoindole derivative, which can emit fluorescence signal at about 425 nm when excited at 365 nm. Effects of pH, flow rate of solutions, concentrations of OPA-reagent, phosphate and sulfite salt were investigated. The calibration curve of ammonium in the range of 0.018-1.8 microg/mL showed a good linear relationship with R2 = 0.9985, and the detection limit was (S/N = 3) 3.6 x 10(-4) microg/mL. The relative standard deviation was 2.8% (n = 11) by calculating at 0.18 microg/mL ammonium for repeated detection. The system was applied to determine the ammonium concentration in rain and river waters, even extent to other analytes fluorescence detection by the presented device.

  9. Detection of chromosome abnormalities by quantitative fluorescent PCR in ectopic pregnancies

    NARCIS (Netherlands)

    Goddijn, Mariette; van Stralen, Marja; Schuring-Blom, Heleen; Redeker, Bert; van Leeuwen, Liesbeth; Repping, Sjoerd; Leschot, Nico; van der Veen, Fulco

    2005-01-01

    Objective: To evaluate the potential value of quantitative fluorescent polymerase chain reaction (QF-PCR) in the detection of chromosome abnormalities in ectopic pregnancies. Methods: Seventy chorionic villi samples of ectopic pregnancies were studied by QF-PCR. Primers for chromosomes 16, 21, X and

  10. Fluorescence detection of flavonols in HPLC by postcolumn chelation with aluminum

    NARCIS (Netherlands)

    Hollman, Peter C H; Van Trijp, J. M P; Buysman, Michel N C P

    1996-01-01

    Flavonols are dietary antioxidants which may prevent coronary heart disease. To be able to study absorption of flavonols in humans, we developed a postcolumn derivatization with aluminum for HPLC with fluorescence detection. Variables governing postcolumn chelation, such as water content, buffer,

  11. Enzyme-enhanced fluorescence detection of DNA on etched optical fibers.

    Science.gov (United States)

    Niu, Shu-yan; Li, Quan-yi; Ren, Rui; Zhang, Shu-sheng

    2009-05-15

    A novel DNA biosensor based on enzyme-enhanced fluorescence detection on etched optical fibers was developed. The hybridization complex of DNA probe and biotinylated target was formed on the etched optical fiber, and was then bound with streptavidin labeled horseradish peroxidase (streptavidin-HRP). The target DNA was quantified through the fluorescent detection of bi-p,p'-4-hydroxyphenylacetic acid (DBDA) generated from the substrate 4-hydroxyphenylacetic acid (p-HPA) under the catalysis of HRP, with a detection limit of 1 pM and a linear range from 1.69 pM to 169 pM. It is facile to regenerate this sensor through surface treatment with concentrated urea solution. It was discovered that the sensor can retain 70% of its original activity after three detection-regeneration cycles.

  12. Bio-inspired photonic-crystal microchip for fluorescent ultratrace detection.

    Science.gov (United States)

    Hou, Jue; Zhang, Huacheng; Yang, Qiang; Li, Mingzhu; Song, Yanlin; Jiang, Lei

    2014-06-02

    Ultratrace detection attracts great interest because it is still a challenge to the early diagnosis and drug testing. Enriching the targets from highly diluted solutions to the sensitive area is a promising method. Inspired by the fog-collecting structure on Stenocara beetle's back, a photonic-crystal (PC) microchip with hydrophilic-hydrophobic micropattern was fabricated by inkjet printing. This device was used to realize high-sensitive ultratrace detection of fluorescence analytes and fluorophore-based assays. Coupled with the fluorescence enhancement effect of a PC, detection down to 10(-16) mol L(-1) was achieved. This design can be combined with biophotonic devices for the detection of drugs, diseases, and pollutions of the ecosystem. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    DEFF Research Database (Denmark)

    Miotke, Laura; Maity, Arindam; Ji, Hanlee

    2015-01-01

    BACKGROUND: Rapid reliable diagnostics of DNA mutations are highly desirable in research and clinical assays. Current development in this field goes simultaneously in two directions: 1) high-throughput methods, and 2) portable assays. Non-enzymatic approaches are attractive for both types...... 1000-fold above the potential detection limit. CONCLUSION: Overall, the novel assay we describe could become a new approach to rapid, reliable and enzyme-free diagnostics of cancer or other associated DNA targets. Importantly, stoichiometry of wild type and mutant targets is conserved in our assay...... of methods since they would allow rapid and relatively inexpensive detection of nucleic acids. Modern fluorescence microscopy is having a huge impact on detection of biomolecules at previously unachievable resolution. However, no straightforward methods to detect DNA in a non-enzymatic way using fluorescence...

  14. Red fluorescence imaging for dental plaque detection and quantification: pilot study

    Science.gov (United States)

    Liu, Zhao; Gomez, Juliana; Khan, Soniya; Peru, Debbie; Ellwood, Roger

    2017-09-01

    The red fluorescence of dental plaque originating from porphyrins in oral bacteria may allow visualization, detection, and scoring of plaque without disclosing agents. Two studies were conducted. The first included 24 healthy participants who abstained from oral hygiene for 24 h. Dental plaque was collected from tooth surfaces, and a 10% solution was prepared. These were scanned by a molecular spectrometer to identify the optimum excitation and emission wavelengths of plaque for developing a red fluorescence imaging system. Fourteen healthy subjects completed the second study. After a washout period (1 week), participants had a prophylaxis at baseline and abstained from oral hygiene during the study. They were monitored using the fluorescence imaging system at baseline, 24 h, and 48 h. A dentist clinically assessed plaque after disclosing and on red fluorescence images. Three descriptors were extracted from images and a RUSBoost classifier derived computer fluorescence scores through cross-validation. Red fluorescence plaque levels increased during the 48-h accumulation. Plaque progression was identified by dentist assessment and computer analysis, presenting significant differences between visits at tooth and subject levels (phygiene assessment.

  15. Sensitive and selective detection of adenine using fluorescent ZnS nanoparticles

    International Nuclear Information System (INIS)

    Meerabai Devi, L; Negi, Devendra P S

    2011-01-01

    We have used fluorescent ZnS nanoparticles as a probe for the determination of adenine. A typical 2 x 10 -7 M concentration of adenine quenches 39.3% of the ZnS fluorescence. The decrease in ZnS fluorescence as a function of adenine concentration was found to be linear in the concentration range 5 x 10 -9 -2 x 10 -7 M. The limit of detection (LOD) of adenine by this method is 3 nM. Among the DNA bases, only adenine quenched the fluorescence of ZnS nanoparticles in the submicromolar concentration range, thus adding selectivity to the method. The amino group of adenine was important in determining the quenching efficiency. Steady-state fluorescence experiments suggest that one molecule of adenine is sufficient to quench the emission arising from a cluster of ZnS consisting of about 20 molecules. Time-resolved fluorescence measurements indicate that the adenine molecules block the sites on the surface of ZnS responsible for emission with the longest lifetime component. This method may be applied for the determination of adenine in biological samples since the measurements have been carried out at pH 7.

  16. Spectroscopic detection of fluorescent protein marker gene activity in genetically modified plants

    Science.gov (United States)

    Liew, O. W.; Chong, Jenny P. C.; Asundi, Anand K.

    2005-04-01

    This work focuses on developing a portable fibre optic fluorescence analyser for rapid identification of genetically modified plants tagged with a fluorescent marker gene. Independent transgenic tobacco plant lines expressing the enhanced green fluorescence protein (EGFP) gene were regenerated following Agrobacterium-mediated gene transfer. Molecular characterisation of these plant lines was carried out at the DNA level by PCR screening to confirm their transgenic status. Conventional transgene expression analysis was then carried out at the RNA level by RT-PCR and at the protein level by Western blotting using anti-GFP rabbit antiserum. The amount of plant-expressed EGFP on a Western blot was quantified against known amounts of purified EGFP by scanning densitometry. The expression level of EGFP in transformed plants was found to range from 0.1 - 0.6% of total extractable protein. A comparison between conventional western analysis of transformants and direct spectroscopic quantification using the fibre optic fluorescence analyser was made. The results showed that spectroscopic measurements of fluorescence emission from strong EGFP expressors correlated positively with Western blot data. However, the fluorescence analyser was also able to identify weakly expressing plant transformants below the detection limit of colorimetric Western blotting.

  17. Сomparative Analysis of 0.266 and 0.355 µm Fluorescence Excitation Wavelengths for Laser Fluores-Cence Monitoring of Oil Pollution Detection

    Directory of Open Access Journals (Sweden)

    M. L. Belov

    2017-01-01

    Full Text Available The on-line detection of pipeline spillage is really essential for the fast oil spill response to the ecological and economical consequences. However existing on-line pipelines spillage detection systems have a sensibility of 0.2 – 1 % of pipe flow and do not detect the smaller-sized spillages.For unpeopled or sparsely populated regions an advanced technique for detection of pipeline spillages (including low-intensity ones is to monitor oil pollution (petroleum spills on the earth surface along the pipeline using, for example, an air drone.The laser remote sensing method is an effective method to detect the pipelines spillage.The paper is dedicated to development of laser fluorescence detection method of oil pollution. The remote sensing laser method to monitor oil pollution is based on the fluorescence excitation of oil in UV spectral band and on the data record of the earth surface laser-induced fluorescence radiation.For laser fluorescence method of monitoring oil pollution the paper presents a comparative analysis  of 0.266 and 0.355 µm wavelengths of the fluorescence excitation in terms of earth atmosphere propagation, eye-safety, laser characteristics, and petroleum fluorescence excitation efficiency.It is shown that in terms of eye-safety, laser characteristics, and propagation in the earth atmosphere a 0.355 µm laser wavelength of the fluorescence excitation has a sure advantage.In the context of petroleum fluorescence excitation efficiency a 0.266 µm laser wavelength of the fluorescence excitation has the advantage, but this advantage depends heavily on the petroleum base. For low-sulfur (sweet oil for instance,  it is not that big.At large, in solving the task of oil pollution detection because of the oil pipeline spillages the 0.355 µm wavelength of fluorescence excitation ought to be preferable. However, when creating a monitoring system for the pipeline with a specific petroleum base the irreversible decision depends on the

  18. In-vivo optical detection of cancer using chlorin e6 – polyvinylpyrrolidone induced fluorescence imaging and spectroscopy

    International Nuclear Information System (INIS)

    Chin, William WL; Thong, Patricia SP; Bhuvaneswari, Ramaswamy; Soo, Khee Chee; Heng, Paul WS; Olivo, Malini

    2009-01-01

    Photosensitizer based fluorescence imaging and spectroscopy is fast becoming a promising approach for cancer detection. The purpose of this study was to examine the use of the photosensitizer chlorin e6 (Ce6) formulated in polyvinylpyrrolidone (PVP) as a potential exogenous fluorophore for fluorescence imaging and spectroscopic detection of human cancer tissue xenografted in preclinical models as well as in a patient. Fluorescence imaging was performed on MGH human bladder tumor xenografted on both the chick chorioallantoic membrane (CAM) and the murine model using a fluorescence endoscopy imaging system. In addition, fiber optic based fluorescence spectroscopy was performed on tumors and various normal organs in the same mice to validate the macroscopic images. In one patient, fluorescence imaging was performed on angiosarcoma lesions and normal skin in conjunction with fluorescence spectroscopy to validate Ce6-PVP induced fluorescence visual assessment of the lesions. Margins of tumor xenografts in the CAM model were clearly outlined under fluorescence imaging. Ce6-PVP-induced fluorescence imaging yielded a specificity of 83% on the CAM model. In mice, fluorescence intensity of Ce6-PVP was higher in bladder tumor compared to adjacent muscle and normal bladder. Clinical results confirmed that fluorescence imaging clearly captured the fluorescence of Ce6-PVP in angiosarcoma lesions and good correlation was found between fluorescence imaging and spectral measurement in the patient. Combination of Ce6-PVP induced fluorescence imaging and spectroscopy could allow for optical detection and discrimination between cancer and the surrounding normal tissues. Ce6-PVP seems to be a promising fluorophore for fluorescence diagnosis of cancer

  19. Detection of Bacterial Endospores in Soil by Terbium Fluorescence

    Directory of Open Access Journals (Sweden)

    Andrea Brandes Ammann

    2011-01-01

    Full Text Available Spore formation is a survival mechanism of microorganisms when facing unfavorable environmental conditions resulting in “dormant” states. We investigated the occurrence of bacterial endospores in soils from various locations including grasslands (pasture, meadow, allotment gardens, and forests, as well as fluvial sediments. Bacterial spores are characterized by their high content of dipicolinic acid (DPA. In the presence of terbium, DPA forms a complex showing a distinctive photoluminescence spectrum. DPA was released from soil by microwaving or autoclaving. The addition of aluminium chloride reduced signal quenching by interfering compounds such as phosphate. The highest spore content (up to 109 spores per gram of dry soil was found in grassland soils. Spore content is related to soil type, to soil depth, and to soil carbon-to-nitrogen ratio. Our study might provide a basis for the detection of “hot spots” of bacterial spores in soil.

  20. Capillary array electrophoresis using laser-excited confocal fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Huang, X.C.; Quesada, M.A.; Mathies, R.A. [Univ. of California, Berkeley, CA (United States)

    1992-04-15

    Capillary electrophoresis (CE) has found widespread application in analytical and biomedical research, and the scope and sophistication of CE is still rapidly advancing. Gel-filled capillaries have been employed for the rapid separation and analysis of synthetic polynucleotides, DNA sequencing fragments, and DNA restriction fragments. Open-tube capillary electrophoresis has attained subattomole detection levels in amino acid separations 14 and proven its utility for the separation of proteins, viruses, and bacteria. Separation of the optical isomers of dansyl amino acids has also been successfully demonstrated. Micellar electrokinetic capillary chromatography, isoelectric focusing, and on-column derivatization can all be performed on CE columns, demonstrating the utility of capillary electrophoresis as an analytical and micropreparative tool. 29 refs., 6 figs., 1 tab.

  1. Specific detection of Vibrio parahaemolyticus by fluorescence quenching immunoassay based on quantum dots.

    Science.gov (United States)

    Wang, Ling; Zhang, Junxian; Bai, Haili; Li, Xuan; Lv, Pintian; Guo, Ailing

    2014-07-01

    In this study, anti-Vibrio parahaemolyticus polyclonal and monoclonal antibodies were prepared through intradermal injection immune and lymphocyte hybridoma technique respectively. CdTe quantum dots (QDs) were synthesized at pH 9.3, 98 °C for 1 h with stabilizer of 2.7:1. The fluorescence intensity was 586.499, and the yield was 62.43%. QD probes were successfully prepared under the optimized conditions of pH 7.4, 37 °C for 1 h, 250 μL of 50 mg/mL EDC · HCl, 150 μL of 4 mg/mL NHS, buffer system of Na2HPO4-citric acid, and 8 μL of 2.48 mg/mL polyclonal antibodies. As gold nanoparticles could quench fluorescence of quantum dots, the concentration of V. parahaemolyticus could be detected through measuring the reduction of fluorescence intensity in immune sandwich reaction composed of quantum dot probe, gold-labeled antibody, and the sample. For pure culture, fluorescence intensity of the system was proportional with logarithm concentration of antigen, and the correlation coefficient was 99.764%. The fluorescence quenching immunoassay based on quantum dots is established for the first time to detect Vibrio parahaemolyticus. This method may be used as rapid testing procedure due to its high simplicity and sensitivity.

  2. Detection of association and fusion of giant vesicles using a fluorescence-activated cell sorter.

    Science.gov (United States)

    Sunami, Takeshi; Caschera, Filippo; Morita, Yuuki; Toyota, Taro; Nishimura, Kazuya; Matsuura, Tomoaki; Suzuki, Hiroaki; Hanczyc, Martin M; Yomo, Tetsuya

    2010-10-05

    We have developed a method to evaluate the fusion process of giant vesicles using a fluorescence-activated cell sorter (FACS). Three fluorescent markers and FACS technology were used to evaluate the extent of association and fusion of giant vesicles. Two fluorescent markers encapsulated in different vesicle populations were used as association markers; when these vesicles associate, the two independent markers should be observed simultaneously in a single detection event. The quenched fluorescent marker and the dequencher, which were encapsulated in separate vesicle populations, were used as the fusion marker. When the internal aqueous solutions mix, the quenched marker is liberated by the dequencher and emits the third fluorescent signal. Although populations of pure POPC vesicles showed no detectable association or fusion, the same populations, oppositely charged by the exogenous addition of charged amphiphiles, showed up to 50% association and 30% fusion upon population analysis of 100,000 giant vesicles. Although a substantial fraction of the vesicles associated in response to a small amount of the charged amphiphiles (5% mole fraction compared to POPC alone), a larger amount of the charged amphiphiles (25%) was needed to induce vesicle fusion. The present methodology also revealed that the association and fusion of giant vesicles was dependent on size, with larger giant vesicles associating and fusing more frequently.

  3. Intrinsic fluorescence for cervical precancer detection using polarized light based in-house fabricated portable device

    Science.gov (United States)

    Meena, Bharat Lal; Singh, Pankaj; Sah, Amar Nath; Pandey, Kiran; Agarwal, Asha; Pantola, Chayanika; Pradhan, Asima

    2018-01-01

    An in-house fabricated portable device has been tested to detect cervical precancer through the intrinsic fluorescence from human cervix of the whole uterus in a clinical setting. A previously validated technique based on simultaneously acquired polarized fluorescence and polarized elastic scattering spectra from a turbid medium is used to extract the intrinsic fluorescence. Using a diode laser at 405 nm, intrinsic fluorescence of flavin adenine dinucleotide, which is the dominant fluorophore and other contributing fluorophores in the epithelium of cervical tissue, has been extracted. Different grades of cervical precancer (cervical intraepithelial neoplasia; CIN) have been discriminated using principal component analysis-based Mahalanobis distance and linear discriminant analysis. Normal, CIN I and CIN II samples have been discriminated from one another with high sensitivity and specificity at 95% confidence level. This ex vivo study with cervix of whole uterus samples immediately after hysterectomy in a clinical environment indicates that the in-house fabricated portable device has the potential to be used as a screening tool for in vivo precancer detection using intrinsic fluorescence.

  4. A miniaturised image based fluorescence detection system for point-of-care-testing of cocaine abuse

    Science.gov (United States)

    Walczak, Rafał; Krüger, Jan; Moynihan, Shane

    2015-08-01

    In this paper, we describe a miniaturised image-based fluorescence detection system and demonstrate its viability as a highly sensitive tool for point-of-care-analysis of drugs of abuse in human sweat with a focus on monitor individuals for drugs of abuse. Investigations of miniaturised and low power optoelectronic configurations and methodologies for real-time image analysis were successfully carried out. The miniaturised fluorescence detection system was validated against a reference detection system under controlled laboratory conditions by analysing spiked sweat samples in dip stick and then strip with sample pad. As a result of the validation studies, a 1 ng mL-1 limit of detection of cocaine in sweat and full agreement of test results with the reference detection system can be reported. Results of the investigations open the way towards a detection system that integrates a hand-held fluorescence reader and a wearable skinpatch, and which can collect and in situ analyse sweat for the presence of cocaine at any point for up to tenths hours.

  5. Integrated three-dimensional optical MEMS for chip-based fluorescence detection

    Science.gov (United States)

    Hung, Kuo-Yung; Tseng, Fan-Gang; Khoo, Hwa-Seng

    2009-04-01

    This paper presents a novel fluorescence sensing chip for parallel protein microarray detection in the context of a 3-in-1 protein chip system. This portable microchip consists of a monolithic integration of CMOS-based avalanche photo diodes (APDs) combined with a polymer micro-lens, a set of three-dimensional (3D) inclined mirrors for separating adjacent light signals and a low-noise transformer-free dc-dc boost mini-circuit to power the APDs (ripple below 1.28 mV, 0-5 V input, 142 V and 12 mA output). We fabricated our APDs using the planar CMOS process so as to facilitate the post-CMOS integration of optical MEMS components such as the lenses. The APD arrays were arranged in unique circular patterns appropriate for detecting the specific fluorescently labelled protein spots in our study. The array-type APDs were designed so as to compensate for any alignment error as detected by a positional error signal algorithm. The condenser lens was used as a structure for light collection to enhance the fluorescent signals by about 25%. This element also helped to reduce the light loss due to surface absorption. We fabricated an inclined mirror to separate two adjacent fluorescent signals from different specimens. Excitation using evanescent waves helped reduce the interference of the excitation light source. This approach also reduced the number of required optical lenses and minimized the complexity of the structural design. We achieved detection floors for anti-rabbit IgG and Cy5 fluorescent dye as low as 0.5 ng/µl (~3.268 nM). We argue that the intrinsic nature of point-to-point and batch-detection methods as showcased in our chip offers advantages over the serial-scanning approach used in traditional scanner systems. In addition, our system is low cost and lightweight.

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

    Science.gov (United States)

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

    2018-08-15

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

  7. Detection of rheumatoid arthritis by evaluation of normalized variances of fluorescence time correlation functions

    Science.gov (United States)

    Dziekan, Thomas; Weissbach, Carmen; Voigt, Jan; Ebert, Bernd; MacDonald, Rainer; Bahner, Malte L.; Mahler, Marianne; Schirner, Michael; Berliner, Michael; Berliner, Birgitt; Osel, Jens; Osel, Ilka

    2011-07-01

    Fluorescence imaging using the dye indocyanine green as a contrast agent was investigated in a prospective clinical study for the detection of rheumatoid arthritis. Normalized variances of correlated time series of fluorescence intensities describing the bolus kinetics of the contrast agent in certain regions of interest were analyzed to differentiate healthy from inflamed finger joints. These values are determined using a robust, parameter-free algorithm. We found that the normalized variance of correlation functions improves the differentiation between healthy joints of volunteers and joints with rheumatoid arthritis of patients by about 10% compared to, e.g., ratios of areas under the curves of raw data.

  8. Supramolecular assembly affording a ratiometric two-photon fluorescent nanoprobe for quantitative detection and bioimaging.

    Science.gov (United States)

    Wang, Peng; Zhang, Cheng; Liu, Hong-Wen; Xiong, Mengyi; Yin, Sheng-Yan; Yang, Yue; Hu, Xiao-Xiao; Yin, Xia; Zhang, Xiao-Bing; Tan, Weihong

    2017-12-01

    Fluorescence quantitative analyses for vital biomolecules are in great demand in biomedical science owing to their unique detection advantages with rapid, sensitive, non-damaging and specific identification. However, available fluorescence strategies for quantitative detection are usually hard to design and achieve. Inspired by supramolecular chemistry, a two-photon-excited fluorescent supramolecular nanoplatform ( TPSNP ) was designed for quantitative analysis with three parts: host molecules (β-CD polymers), a guest fluorophore of sensing probes (Np-Ad) and a guest internal reference (NpRh-Ad). In this strategy, the TPSNP possesses the merits of (i) improved water-solubility and biocompatibility; (ii) increased tissue penetration depth for bioimaging by two-photon excitation; (iii) quantitative and tunable assembly of functional guest molecules to obtain optimized detection conditions; (iv) a common approach to avoid the limitation of complicated design by adjustment of sensing probes; and (v) accurate quantitative analysis by virtue of reference molecules. As a proof-of-concept, we utilized the two-photon fluorescent probe NHS-Ad-based TPSNP-1 to realize accurate quantitative analysis of hydrogen sulfide (H 2 S), with high sensitivity and good selectivity in live cells, deep tissues and ex vivo -dissected organs, suggesting that the TPSNP is an ideal quantitative indicator for clinical samples. What's more, TPSNP will pave the way for designing and preparing advanced supramolecular sensors for biosensing and biomedicine.

  9. Chemodosimeter-based fluorescent detection of L-cysteine after extracted by molecularly imprinted polymers.

    Science.gov (United States)

    Cai, Xiaoqiang; Li, Jinhua; Zhang, Zhong; Wang, Gang; Song, Xingliang; You, Jinmao; Chen, Lingxin

    2014-03-01

    A chemodosimeter-based fluorescent detection method coupled with molecularly imprinted polymers (MIPs) extraction was developed for determination of L-cysteine (L-Cys) by combining molecular imprinting technique with fluorescent chemodosimeter. The MIPs prepared by precipitation polymerization with L-Cys as template, possessed high specific surface area of 145 m(2)/g and good thermal stability without decomposition lower than 300 °C, and were successfully applied as an adsorbent with excellent selectivity for L-Cys over other amino acids, and enantioselectivity was also demonstrated. A novel chemodosimeter, rhodamine B1, was synthesized for discriminating L-Cys from its structurally similar homocysteine and glutathione as well as various possibly co-existing biospecies in aqueous solutions with notable fluorescence enhancement when adding L-Cys. As L-Cys was added with increasing concentrations, an emission band peaked at 580 nm occurred and significantly increased in fluorescence intensity, by which the L-Cys could be sensed optically. High detectability up to 12.5 nM was obtained. An excellent linearity was found within the wide range of 0.05-50 μM (r=0.9996), and reasonable relative standard deviations ranging from 0.3% to 3.5% were attained. Such typical features as high selectivity, high sensitivity, easy operation and low cost enabled this MIPs-fluorometry to be potentially applicable for routine detection of trace L-Cys. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Concentrations of Nicotinamide in Plasma by RP-HPLC With Fluorescence Detection

    Directory of Open Access Journals (Sweden)

    Pan Zhipeng

    2016-01-01

    Full Text Available The purpose of this study is to establish a new method for detecting nicotinamide concentration in plasma. In the experiment, the high performance liquid chromatography (HPLC method was used, with a fluorescence detector. The nicotinamide in the plasma was first converted to N1- methylnicotinamide, then reacted with acetophenone under certain conditions to produce fluorescent derivatives for testing. The method is a kind of highly sensitive detection, of which the lower limit is 10 ng/mL, the recovery rate is between 92.75% and 105.13%, and the relative standard deviation (RSD is between 3.76% and 4.43%. The results showed that this measurement method is accurate, sensitive and rapid. It meets the requirements of the experiment, and applies to the detection of nicotinamide concentration in plasma.

  11. Design of a smartphone-camera-based fluorescence imaging system for the detection of oral cancer

    Science.gov (United States)

    Uthoff, Ross

    Shown is the design of the Smartphone Oral Cancer Detection System (SOCeeDS). The SOCeeDS attaches to a smartphone and utilizes its embedded imaging optics and sensors to capture images of the oral cavity to detect oral cancer. Violet illumination sources excite the oral tissues to induce fluorescence. Images are captured with the smartphone's onboard camera. Areas where the tissues of the oral cavity are darkened signify an absence of fluorescence signal, indicating breakdown in tissue structure brought by precancerous or cancerous conditions. With this data the patient can seek further testing and diagnosis as needed. Proliferation of this device will allow communities with limited access to healthcare professionals a tool to detect cancer in its early stages, increasing the likelihood of cancer reversal.

  12. Detection of biological warfare agents using ultra violet-laser induced fluorescence LIDAR.

    Science.gov (United States)

    Joshi, Deepti; Kumar, Deepak; Maini, Anil K; Sharma, Ramesh C

    2013-08-01

    This review has been written to highlight the threat of biological warfare agents, their types and detection. Bacterial biological agent Bacillus anthracis (bacteria causing the disease anthrax) which is most likely to be employed in biological warfare is being discussed in detail. Standoff detection of biological warfare agents in aerosol form using Ultra violet-Laser Induced Fluorescence (UV-LIF) spectroscopy method has been studied. Range-resolved detection and identification of biological aerosols by both nano-second and non-linear femto-second LIDAR is also discussed. Calculated received fluorescence signal for a cloud of typical biological agent Bacillus globigii (Simulants of B. anthracis) at a location of ~5.0 km at different concentrations in presence of solar background radiation has been described. Overview of current research efforts in internationally available working UV-LIF LIDAR systems are also mentioned briefly. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Interactions of Insolation and Shading on Ability to Use Fluorescence Imaging to Detect Fecal Contaminated Spinach

    Directory of Open Access Journals (Sweden)

    Alan M. Lefcourt

    2017-10-01

    Full Text Available Fecal contamination of produce in fields is a recognized food safety risk, and it is a requirement that fields be surveyed for evidence of fecal contamination. It may be possible to increase the efficacy of such surveys using imaging techniques that rely on detection of fluorescence responses of fecal material to UV excitation. However, fluorescence responses are easily masked by ambient illumination. This study investigated the potential of using a shroud to reduce the impact of ambient illumination on responses measured using relatively inexpensive optical components. During periods of near peak insolation, even with full shrouding, results indicate that reliable detection would be problematic. Towards dusk, effective imaging could be accomplished even with a gap of 250 cm at the bottom of the shroud. Results suggest that imaging using relatively inexpensive components could provide the basis for detection of fecal contamination in produce fields if surveys were conducted during dawn or dusk, or at night.

  14. Protein A Detection Based on Quantum Dots-Antibody Bioprobe Using Fluorescence Coupled Capillary Electrophoresis

    Directory of Open Access Journals (Sweden)

    Lin Qiu

    2014-01-01

    Full Text Available In this report, fluorescence detection coupled capillary electrophoresis (CE-FL was used to detect Protein A. Antibody was first labeled with Cy5 and then mixed with quantum dots (QDs to form QDs-antibody bioprobe. Further, we observed fluorescence resonance energy transfer (FRET from QDs donor to Cy5 acceptor. The bioprobe was formed and brought QDs and Cy5 close enough to allow FRET to occur. After adding protein A, the FRET system was broken and caused the FRET signal to decrease. Thus, a new method for the determination of protein A was proposed based on the FRET signal changes. This study provides a new trail of thought for the detection of protein.

  15. Rapid fluorescence detection of pathogenic bacteria using magnetic enrichment technique combined with magnetophoretic chromatography.

    Science.gov (United States)

    Che, Yulan; Xu, Yi; Wang, Renjie; Chen, Li

    2017-08-01

    A rapid and sensitive analytical method was developed to detect pathogenic bacteria which combined magnetic enrichment, fluorescence labeling with polyethylene glycol (PEG) magnetophoretic chromatography. As pathogenic bacteria usually exist in complex matrixes at low concentration, an efficient enrichment is essential for diagnosis. In order to capture series types of pathogenic bacteria in samples, amino-modified magnetic nanoparticles (Fe 3 O 4 @SiO 2 -NH 2 ) were prepared for efficient enrichment by the electrostatic interaction with pathogenic bacteria. It was shown that the capture efficiency reached up to 95.4% for Escherichia coli (E. coli). Furthermore, quantitative analysis of the bacteria was achieved by using acridine orange (AO) as a fluorescence probe for the captured E. coli due to its ability of staining series types of bacteria and rapid labeling. In order to remove the free magnetic nanoparticles and redundant fluorescent reagent, the labeled suspension was poured into a PEG separation column and was separated by applying an external magnetic field. The presence of 100 cfu mL -1 E. coli could be detected for semi-quantitative analysis by observing the separation column with the naked eye, and the concentration could be further evaluated by fluorescence detection. All the above processes were finished within 80 min. It was demonstrated that a good linear relationship existed between the fluorescence intensity and the concentration of E. coli ranging from 10 2 to 10 6  cfu mL -1 , with a detection limit of 100 cfu mL -1 when E. coli acted as target bacteria. The recovery rate of E. coli was 93.6∼102.0% in tap water and cooked meat samples, and the RSD was lower than 7% (n = 6); the result coincided with the conventional plate count method. Graphical abstract ᅟ.

  16. The use of fluorescent intrabodies to detect endogenous gankyrin in living cancer cells

    International Nuclear Information System (INIS)

    Rinaldi, Anne-Sophie; Freund, Guillaume; Desplancq, Dominique; Sibler, Annie-Paule; Baltzinger, Mireille; Rochel, Natacha; Mély, Yves; Didier, Pascal; Weiss, Etienne

    2013-01-01

    Expression of antibody fragments in mammalian cells (intrabodies) is used to probe the target protein or interfere with its biological function. We previously described the in vitro characterisation of a single-chain Fv (scFv) antibody fragment (F5) isolated from an intrabody library that binds to the oncoprotein gankyrin (GK) in solution. Here, we have isolated several other scFvs that interact with GK in the presence of F5 and tested whether they allow, when fused to fluorescent proteins, to detect by FRET endogenous GK in living cells. The binding of pairs of scFvs to GK was analysed by gel filtration and the ability of each scFv to mediate nuclear import/export of GK was determined. Binding between scFv-EGFP and RFP-labelled GK in living cells was detected by fluorescence lifetime imaging microscopy (FLIM). After co-transfection of two scFvs fused to EGFP and RFP, respectively, which form a tri-molecular complex with GK in vitro, FRET signal was measured. This system allowed us to observe that GK is monomeric and distributed throughout the cytoplasm and nucleus of several cancer cell lines. Our results show that pairs of fluorescently labelled intrabodies can be monitored by FLIM–FRET microscopy and that this technique allows the detection of lowly expressed endogenous proteins in single living cells. Highlights: ► Endogenous GK in living cells was targeted with pairs of fluorescently-tagged scFvs. ► Tri-molecular complexes containing two scFvs and one molecule GK were formed. ► GK was detected using fluorescence lifetime-based FRET imaging. ► GK is monomeric and homogeneously distributed in several cancer cell lines. ► This technique may have many applications in live-cell imaging of endogenous proteins

  17. The use of fluorescent intrabodies to detect endogenous gankyrin in living cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldi, Anne-Sophie; Freund, Guillaume; Desplancq, Dominique; Sibler, Annie-Paule; Baltzinger, Mireille [Ecole Supérieure de Biotechnologie de Strasbourg, UMR 7242, CNRS/Université de Strasbourg, boulevard Sébastien Brant, 67412 Illkirch (France); Rochel, Natacha [Institut de Génétique et de Biologie Moléculaire et Cellulaire, UMR 7104, CNRS/INSERM/Université de Strasbourg, rue Laurent Fries, 67404 Illkirch (France); Mély, Yves; Didier, Pascal [Faculté de Pharmacie, UMR 7213, CNRS/Université de Strasbourg, route du Rhin, 67401 Illkirch (France); Weiss, Etienne, E-mail: eweiss@unistra.fr [Ecole Supérieure de Biotechnologie de Strasbourg, UMR 7242, CNRS/Université de Strasbourg, boulevard Sébastien Brant, 67412 Illkirch (France)

    2013-04-01

    Expression of antibody fragments in mammalian cells (intrabodies) is used to probe the target protein or interfere with its biological function. We previously described the in vitro characterisation of a single-chain Fv (scFv) antibody fragment (F5) isolated from an intrabody library that binds to the oncoprotein gankyrin (GK) in solution. Here, we have isolated several other scFvs that interact with GK in the presence of F5 and tested whether they allow, when fused to fluorescent proteins, to detect by FRET endogenous GK in living cells. The binding of pairs of scFvs to GK was analysed by gel filtration and the ability of each scFv to mediate nuclear import/export of GK was determined. Binding between scFv-EGFP and RFP-labelled GK in living cells was detected by fluorescence lifetime imaging microscopy (FLIM). After co-transfection of two scFvs fused to EGFP and RFP, respectively, which form a tri-molecular complex with GK in vitro, FRET signal was measured. This system allowed us to observe that GK is monomeric and distributed throughout the cytoplasm and nucleus of several cancer cell lines. Our results show that pairs of fluorescently labelled intrabodies can be monitored by FLIM–FRET microscopy and that this technique allows the detection of lowly expressed endogenous proteins in single living cells. Highlights: ► Endogenous GK in living cells was targeted with pairs of fluorescently-tagged scFvs. ► Tri-molecular complexes containing two scFvs and one molecule GK were formed. ► GK was detected using fluorescence lifetime-based FRET imaging. ► GK is monomeric and homogeneously distributed in several cancer cell lines. ► This technique may have many applications in live-cell imaging of endogenous proteins.

  18. Biosynthesis of CdS nanoparticles: A fluorescent sensor for sulfate-reducing bacteria detection.

    Science.gov (United States)

    Qi, Peng; Zhang, Dun; Zeng, Yan; Wan, Yi

    2016-01-15

    CdS nanoparticles were synthesized with an environmentally friendly method by taking advantage of the characteristic metabolic process of sulfate-reducing bacteria (SRB), and used as fluorescence labels for SRB detection. The presence of CdS nanoparticles was observed within and immediately surrounded bacterial cells, indicating CdS nanoparticles were synthesized both intracellularly and extracellularly. Moreover, fluorescent properties of microbial synthesized CdS nanoparticles were evaluated for SRB detection, and a linear relationship between fluorescence intensity and the logarithm of bacterial concentration was obtained in the range of from 1.0×10(2) to 1.0×10(7)cfu mL(-1). The proposed SRB detection method avoided the use of biological bio-recognition elements which are easy to lose their specific recognizing abilities, and the bacterial detection time was greatly shortened compared with the widely used MPN method which would take up to 15 days to accomplish the detection process. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Ratio-metric sensor to detect riboflavin via fluorescence resonance energy transfer with ultrahigh sensitivity

    Science.gov (United States)

    Wang, Jilong; Su, Siheng; Wei, Junhua; Bahgi, Roya; Hope-Weeks, Louisa; Qiu, Jingjing; Wang, Shiren

    2015-08-01

    In this paper, a novel fluorescence resonance energy transfer (FRET) ration-metric fluorescent probe based on heteroatom N, S doped carbon dots (N, S-CDs) was developed to determine riboflavin in aqueous solutions. The ratio of two emission intensities at different wavelengths is applied to determine the concentration of riboflavin (RF). This method is more effective in reducing the background interference and fluctuation of diverse conditions. Therefore, this probe obtains high sensitivity with a low limit of detection (LOD) of 1.9 nM (0.7 ng/ml) which is in the highest level of all riboflavin detection approaches and higher than single wavelength intensity detection (1.9 μM). In addition, this sensor has a high selectivity of detecting riboflavin in deionized water (pH=7) with other biochemical like amino acids. Moreover, riboflavin in aqueous solution is very sensitive to sunlight and can be degraded to lumiflavin, which is toxic. Because the N, S doped carbon dots cannot serve as an energy donor for N, S doped carbon dots and lumiflavin system, this system makes it easy to determine whether the riboflavin is degraded or not, which is first to be reported. This platform may provide possibilities to build a new and facile fluorescence resonance energy transfer based sensor to detect analytes and metamorphous analytes in aqueous solution.

  20. Direct fluorescence detection of VirE2 secretion by Agrobacterium tumefaciens

    Science.gov (United States)

    Yaakov, Noga; Barak, Yoav; Pereman, Idan; Christie, Peter J.; Elbaum, Michael

    2017-01-01

    VirE2 is a ssDNA binding protein essential for virulence in Agrobacterium tumefaciens. A tetracysteine mutant (VirE2-TC) was prepared for in vitro and in vivo fluorescence imaging based on the ReAsH reagent. VirE2-TC was found to be biochemically active as it binds both ssDNA and the acidic secretion chaperone VirE1. It was also biologically functional in complementing virE2 null strains transforming Arabidopsis thaliana roots and Nicotiana tabacum leaves. In vitro experiments demonstrated a two-color fluorescent complex using VirE2-TC/ReAsH and Alexa Fluor 488 labeled ssDNA. In vivo, fluorescent VirE2-TC/ReAsH was detected in bacteria and in plant cells at time frames relevant to transformation. PMID:28403156

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

    Science.gov (United States)

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

    2018-01-01

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

  2. Detection of ultra-low oxygen concentration based on the fluorescence blinking dynamics of single molecules

    Science.gov (United States)

    Wu, Ruixiang; Chen, Ruiyun; Zhou, Haitao; Qin, Yaqiang; Zhang, Guofeng; Qin, Chengbing; Gao, Yan; Gao, Yajun; Xiao, Liantuan; Jia, Suotang

    2018-01-01

    We present a sensitive method for detection of ultra-low oxygen concentrations based on the fluorescence blinking dynamics of single molecules. The relationship between the oxygen concentration and the fraction of time spent in the off-state, stemming from the population and depopulation of triplet states and radical cationic states, can be fitted with a two-site quenching model in the Stern-Volmer plot. The oxygen sensitivity is up to 43.42 kPa-1 in the oxygen partial pressure region as low as 0.01-0.25 kPa, which is seven times higher than that of the fluorescence intensity indicator. This method avoids the limitation of the sharp and non-ignorable fluctuations that occur during the measurement of fluorescence intensity, providing potential applications in the field of low oxygen-concentration monitoring in life science and industry.

  3. Detection of potassium deficiency on palm oil tree (Elaeis guineensis (jacq)) by laser induced fluorescence

    International Nuclear Information System (INIS)

    Diomande, K.; Konate, A.; Krou Adjo, V.; Soro, A.; Ebby, N.; Ballo, K.

    1998-02-01

    The potassium is the main nutrient element which plays a significant role on oil palm tree (Elaeis guineensis (jacq)) production and its resistance to the dry season. One can observe 30% decrease of the production in case of potassium deficiency. The potassium nutrition control of an oil palm tree field is a very important activity and leads to the fertilization policy. The Laser Induced Fluorescence (L.I.F.) is a fast and simple method compared to the classical one, ''Diagnostic Foliaire'', usually used in agronomy. We used the L.I.F. method to detect the oil palm tree stress caused by potassium deficiency, analysing the fluorescence spectrum of the chlorophyll a. We proved that the intensity ratio of the fluorescence spectrum R=F690/F73S is superior to 0.5 when the tree is under stress and its value is around 0.4 in case of intact tree. (author)

  4. Salicylimine-Based Colorimetric and Fluorescent Chemosensor for Selective Detection of Cyanide in Aqueous Buffer

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Jin Young; Hwang, In Hong; Kim, Hyun; Song, Eun Joo; Kim, Kyung Beom; Kim, Cheal [Seoul National Univ., Seoul (Korea, Republic of)

    2013-07-15

    A simple colorimetric and fluorescent anion sensor 1 based on salicylimine showed a high selectivity and sensitivity for detection of cyanide in aqueous solution. The receptor 1 showed high selectivity toward CN{sup -} ions in a 1:1 stoichiometric manner, which induces a fast color change from colorless to orange and a dramatic enhancement in fluorescence intensity selectively for cyanide anions over other anions. Such selectivity resulted from the nucleophilic addition of CN{sup -} to the carbon atom of an electron-deficient imine group. The sensitivity of the fluorescence-based assay (0.06 μM) is below the 1.9 μM suggested by the World Health Organization (WHO) as the maximum allowable cyanide concentration in drinking water, capable of being a practical system for the monitoring of CN. concentrations in aqueous samples.

  5. Multiplex and high-throughput DNA detection using surface plasmon mediated fluorescence

    Science.gov (United States)

    Mei, Zhong

    The overall objective of this research project was to develop a user-friendly and sensitive biosensor for nucleic acid aptamers with multiplexing and high-throughput capability. The sensing was based on the fluorescence signals emitted by the fluorophores coupling with plamonic nanoparticle (gold nanorod) deposited on a patterned substrate. Gold nanorods (GNRs) were synthesized using a binary mixture of hexadecyltrimethylammonium bromide (CTAB) and sodium oleate (NaOL) in seed mediated growth method. Polytetrafluoroethylene (PTFE) printed glass slides were selectively coated with a gold thin-film to define hydrophilic areas for GNR deposition. Due to the wettablity contrast, GNR solution dropped on the slide was induced to assemble exclusively in the hydrophilic spots. By controlling temperature and humidity of the evaporation process, vertically-standing GNR arrays were achieved on the pattered slide. Fluorescence was conjugated to GNR surface via DNA double strand with tunable length. Theoretical simulation predicted a flat layer ( 30 nm thick) of uniform "hot spots" presented on the GNR tips, which could modify the nearby fluorescence. Experimentally, the vertical GNR arrays yielded metallic enhanced fluorescence (MEF) effect, which was dependent on the spectrum overlap and GNR-fluorophore distance. Specifically, the maximum enhancement of Quasar 670 and Alexa 750 was observed when it was coupled with GNR664 (plasmonic wavelength 664 nm) and GNR778 respectively at a distance of 16 nm, while the carboxyfluorescein (FAM) was at maximal intensity when attached to gold nanosphere520. This offers an opportunity for multiplexed DNA sensing. Based on this, we developed a novel GNR mediated fluorescence biosensor for DNA detection. Fluorescence labeled haipin-DNA probes were introduced to designated spots of GNR array with the matching LSPR wavelengths on the substrate. The fluorescence was quenched originally because of Forster resonance energy transfer (FRET) effect

  6. Metal plasmon-coupled fluorescence imaging and label free coenzyme detection in cells

    International Nuclear Information System (INIS)

    Zhang, Jian; Fu, Yi; Li, Ge; Zhao, Richard Y.

    2012-01-01

    Highlights: ► Metal nanoparticle for fluorescence cell imaging. ► Non-invasive emission detection of coenzyme in cell on time-resolved confocal microscope. ► Near-field interaction of flavin adenine dinucleotide with silver substrate. ► Isolation of emissions by coenzymes from cellular autofluorescence on fluorescence cell imaging. -- Abstract: Flavin adenine dinucleotide (FAD) is a key metabolite in cellular energy conversion. Flavin can also bind with some enzymes in the metabolic pathway and the binding sites may be changed due to the disease progression. Thus, there is interest on studying its expression level, distribution, and redox state within the cells. FAD is naturally fluorescent, but it has a modest extinction coefficient and quantum yield. Hence the intrinsic emission from FAD is generally too weak to be isolated distinctly from the cellular backgrounds in fluorescence cell imaging. In this article, the metal nanostructures on the glass coverslips were used as substrates to measure FAD in cells. Particulate silver films were fabricated with an optical resonance near the absorption and the emission wavelengths of FAD which can lead to efficient coupling interactions. As a result, the emission intensity and quantum yield by FAD were greatly increased and the lifetime was dramatically shortened resulting in less interference from the longer lived cellular background. This feature may overcome the technical limits that hinder the direct observation of intrinsically fluorescent coenzymes in the cells by fluorescence microscopy. Fluorescence cell imaging on the metallic particle substrates may provide a non-invasive strategy for collecting the information of coenzymes in cells.

  7. Metal plasmon-coupled fluorescence imaging and label free coenzyme detection in cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian, E-mail: jian@cfs.bioment.umaryland.edu [Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, MD 21201 (United States); Fu, Yi [Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, MD 21201 (United States); Li, Ge [Division of Molecular Pathology, Department of Pathology, University of Maryland School of Medicine, 10 South Pine Street, Baltimore, MD 21201 (United States); Zhao, Richard Y. [Division of Molecular Pathology, Department of Pathology, University of Maryland School of Medicine, 10 South Pine Street, Baltimore, MD 21201 (United States); Department of Microbiology-Immunology, University of Maryland School of Medicine, 10 South Pine Street, Baltimore, MD 21201 (United States); Institute of Human Virology, University of Maryland School of Medicine, 10 South Pine Street, Baltimore, MD 21201 (United States)

    2012-08-31

    Highlights: Black-Right-Pointing-Pointer Metal nanoparticle for fluorescence cell imaging. Black-Right-Pointing-Pointer Non-invasive emission detection of coenzyme in cell on time-resolved confocal microscope. Black-Right-Pointing-Pointer Near-field interaction of flavin adenine dinucleotide with silver substrate. Black-Right-Pointing-Pointer Isolation of emissions by coenzymes from cellular autofluorescence on fluorescence cell imaging. -- Abstract: Flavin adenine dinucleotide (FAD) is a key metabolite in cellular energy conversion. Flavin can also bind with some enzymes in the metabolic pathway and the binding sites may be changed due to the disease progression. Thus, there is interest on studying its expression level, distribution, and redox state within the cells. FAD is naturally fluorescent, but it has a modest extinction coefficient and quantum yield. Hence the intrinsic emission from FAD is generally too weak to be isolated distinctly from the cellular backgrounds in fluorescence cell imaging. In this article, the metal nanostructures on the glass coverslips were used as substrates to measure FAD in cells. Particulate silver films were fabricated with an optical resonance near the absorption and the emission wavelengths of FAD which can lead to efficient coupling interactions. As a result, the emission intensity and quantum yield by FAD were greatly increased and the lifetime was dramatically shortened resulting in less interference from the longer lived cellular background. This feature may overcome the technical limits that hinder the direct observation of intrinsically fluorescent coenzymes in the cells by fluorescence microscopy. Fluorescence cell imaging on the metallic particle substrates may provide a non-invasive strategy for collecting the information of coenzymes in cells.

  8. Detection of {alpha} particles with the aid of a fluorescence counter; Detection des particules {alpha} a l'aide d'un compteur a fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Koechlin, Y

    1951-07-01

    The operation principle of the fluorescence counter, used as {alpha} particles detector, is analyzed in the first part. Detection can be done in two ways: by counting the pulses due to each {alpha} particle, or by integrating all pulses and measuring the average current obtained. In the second part, three series of measurements are presented: 1 - two fluorescent substances (zinc sulfate and anthracene) are placed in front of the photocathode of three types of photomultipliers (RCA 931A, EMI 4588, and EMI 5311). These substances are bombarded with the {alpha} radiations of a Po source and then irradiated by the {beta} and {gamma} radiations of a Ra source in order to study the light emission of these thin film substances when submitted to the three types of radiations. The results show that thanks to the amplitude of the emitted light pulses, the fluorescence counter, when submitted to the three types of radiations, allows to distinguish between the {alpha} radiations of the polonium and the {beta} and {gamma} radiations of the radium source. The output current of a 931A, when measured with a galvanometer, allows to detect Po sources with an intensity of about 10{sup -6} curie. This is observed when its photocathode receives the light from a ZnS-Ag coating bombarded by the {alpha} particles of Po. The quantum efficiency of the counter is close to 100% for the {alpha} particles of Po. This efficiency is evaluated by comparison with the efficiency of a thin wall Geiger-Mueller counter. Moreover, when a thin crystal of anthracene is used as detector, the energy of the incident particles can be measured with a 2% preciseness. (J.S.)

  9. Real-time label-free quantitative fluorescence microscopy-based detection of ATP using a tunable fluorescent nano-aptasensor platform.

    Science.gov (United States)

    Shrivastava, Sajal; Sohn, Il-Yung; Son, Young-Min; Lee, Won-Il; Lee, Nae-Eung

    2015-12-14

    Although real-time label-free fluorescent aptasensors based on nanomaterials are increasingly recognized as a useful strategy for the detection of target biomolecules with high fidelity, the lack of an imaging-based quantitative measurement platform limits their implementation with biological samples. Here we introduce an ensemble strategy for a real-time label-free fluorescent graphene (Gr) aptasensor platform. This platform employs aptamer length-dependent tunability, thus enabling the reagentless quantitative detection of biomolecules through computational processing coupled with real-time fluorescence imaging data. We demonstrate that this strategy effectively delivers dose-dependent quantitative readouts of adenosine triphosphate (ATP) concentration on chemical vapor deposited (CVD) Gr and reduced graphene oxide (rGO) surfaces, thereby providing cytotoxicity assessment. Compared with conventional fluorescence spectrometry methods, our highly efficient, universally applicable, and rational approach will facilitate broader implementation of imaging-based biosensing platforms for the quantitative evaluation of a range of target molecules.

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

    Science.gov (United States)

    Harbater, Osnat; Gannot, Israel

    2014-03-01

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

  11. Breaking the color barrier - a multi-selective antibody reporter offers innovative strategies of fluorescence detection.

    Science.gov (United States)

    Gallo, Eugenio; Jarvik, Jonathan W

    2017-08-01

    A novel bi-partite fluorescence platform exploits the high affinity and selectivity of antibody scaffolds to capture and activate small-molecule fluorogens. In this report, we investigated the property of multi-selectivity activation by a single antibody against diverse cyanine family fluorogens. Our fluorescence screen identified three cell-impermeant fluorogens, each with unique emission spectra (blue, green and red) and nanomolar affinities. Most importantly, as a protein fusion tag to G-protein-coupled receptors, the antibody biosensor retained full activity - displaying bright fluorogen signals with minimal background on live cells. Because fluorogen-activating antibodies interact with their target ligands via non-covalent interactions, we were able to perform advanced multi-color detection strategies on live cells, previously difficult or impossible with conventional reporters. We found that by fine-tuning the concentrations of the different color fluorogen molecules in solution, a user may interchange the fluorescence signal (onset versus offset), execute real-time signal exchange via fluorogen competition, measure multi-channel fluorescence via co-labeling, and assess real-time cell surface receptor traffic via pulse-chase experiments. Thus, here we inform of an innovative reporter technology based on tri-color signal that allows user-defined fluorescence tuning in live-cell applications. © 2017. Published by The Company of Biologists Ltd.

  12. Conditional-sampling spectrograph detection system for fluorescence measurements of individual airborne biological particles

    Science.gov (United States)

    Nachman, Paul; Pinnick, R. G.; Hill, Steven C.; Chen, Gang; Chang, Richard K.; Mayo, Michael W.; Fernandez, Gilbert L.

    1996-03-01

    We report the design and operation of a prototype conditional-sampling spectrograph detection system that can record the fluorescence spectra of individual, micrometer-sized aerosols as they traverse an intense 488-nm intracavity laser beam. The instrument's image-intensified CCD detector is gated by elastic scattering or by undispersed fluorescence from particles that enter the spectrograph's field of view. It records spectra only from particles with preselected scattering-fluorescence levels (a fiber-optic-photomultiplier subsystem provides the gating signal). This conditional-sampling procedure reduces data-handling rates and increases the signal-to-noise ratio by restricting the system's exposures to brief periods when aerosols traverse the beam. We demonstrate these advantages by reliably capturing spectra from individual fluorescent microspheres dispersed in an airstream. The conditional-sampling procedure also permits some discrimination among different types of particles, so that spectra may be recorded from the few interesting particles present in a cloud of background aerosol. We demonstrate such discrimination by measuring spectra from selected fluorescent microspheres in a mixture of two types of microspheres, and from bacterial spores in a mixture of spores and nonfluorescent kaolin particles.

  13. Highly selective and reversible chemosensor for Pd(2+) detected by fluorescence, colorimetry, and test paper.

    Science.gov (United States)

    Wang, Mian; Liu, Xiaomei; Lu, Huizhe; Wang, Hongmei; Qin, Zhaohai

    2015-01-21

    A "turn-on" fluorescent and colorimetric chemosensor (RBS) for Pd(2+) has been designed and synthesized through introduction of sulfur as a ligand atom to Rhodamine B. RBS exhibits high selectivity (freedom from the interference of Hg(2+ )in particular) and sensitivity toward Pd(2+) with a detection limit as low as 2.4 nM. RBS is also a reversible sensor, and it can be made into test paper to detect Pd(2+) in pure water. Compared to the chemosensors that introduced phosphorus to Rhodamine to detect Pd(2+), RBS can be synthesized more simply and economically.

  14. Highly sensitive rapid fluorescence detection of protein residues on surgical instruments

    International Nuclear Information System (INIS)

    Kovalev, Valeri I; Bartona, James S; Richardson, Patricia R; Jones, Anita C

    2006-01-01

    There is a risk of contamination of surgical instruments by infectious protein residues, in particular, prions which are the agents for Creutzfeldt-Jakob Disease in humans. They are exceptionally resistant to conventional sterilization, therefore it is important to detect their presence as contaminants so that alternative cleaning procedures can be applied. We describe the development of an optimized detection system for fluorescently labelled protein, suitable for in-hospital use. We show that under optimum conditions the technique can detect ∼10 attomole/cm 2 with a scan speed of ∼3-10 cm 2 /s of the test instrument's surface. A theoretical analysis and experimental measurements will be discussed

  15. Quaternary ammonium promoted ultra selective and sensitive fluorescence detection of fluoride ion in water and living cells.

    Science.gov (United States)

    Li, Long; Ji, Yuzhuo; Tang, Xinjing

    2014-10-21

    Highly selective and sensitive fluorescent probes with a quaternary ammonium moiety have been rationally designed and developed for fast and sensitive fluorescence detection of fluoride ion (F(-) from NaF, not TBAF) in aqueous solution and living cells. With the sequestration effect of quaternary ammonium, the detection time was less than 2 min and the detection limit of fluoride ion was as low as 0.57 ppm that is among the lowest detection limits in aqueous solutions of many fluoride fluorescence probes in the literature.

  16. Real-time label-free quantitative fluorescence microscopy-based detection of ATP using a tunable fluorescent nano-aptasensor platform

    Science.gov (United States)

    Shrivastava, Sajal; Sohn, Il-Yung; Son, Young-Min; Lee, Won-Il; Lee, Nae-Eung

    2015-11-01

    Although real-time label-free fluorescent aptasensors based on nanomaterials are increasingly recognized as a useful strategy for the detection of target biomolecules with high fidelity, the lack of an imaging-based quantitative measurement platform limits their implementation with biological samples. Here we introduce an ensemble strategy for a real-time label-free fluorescent graphene (Gr) aptasensor platform. This platform employs aptamer length-dependent tunability, thus enabling the reagentless quantitative detection of biomolecules through computational processing coupled with real-time fluorescence imaging data. We demonstrate that this strategy effectively delivers dose-dependent quantitative readouts of adenosine triphosphate (ATP) concentration on chemical vapor deposited (CVD) Gr and reduced graphene oxide (rGO) surfaces, thereby providing cytotoxicity assessment. Compared with conventional fluorescence spectrometry methods, our highly efficient, universally applicable, and rational approach will facilitate broader implementation of imaging-based biosensing platforms for the quantitative evaluation of a range of target molecules.Although real-time label-free fluorescent aptasensors based on nanomaterials are increasingly recognized as a useful strategy for the detection of target biomolecules with high fidelity, the lack of an imaging-based quantitative measurement platform limits their implementation with biological samples. Here we introduce an ensemble strategy for a real-time label-free fluorescent graphene (Gr) aptasensor platform. This platform employs aptamer length-dependent tunability, thus enabling the reagentless quantitative detection of biomolecules through computational processing coupled with real-time fluorescence imaging data. We demonstrate that this strategy effectively delivers dose-dependent quantitative readouts of adenosine triphosphate (ATP) concentration on chemical vapor deposited (CVD) Gr and reduced graphene oxide (r

  17. Speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li Xun [Department of Chemistry, Beijing Normal University, Beijing 100875 (China); Department of Chemistry and Life Science, Gannan Teachers College, Ganzhou 341000 (China); Jia Jing [Department of Chemistry, Beijing Normal University, Beijing 100875 (China); Wang Zhenghao [Department of Chemistry, Beijing Normal University, Beijing 100875 (China)]. E-mail: zhwang@bnu.edu.cn

    2006-02-23

    A simple procedure was developed for the speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry (EcHG-AAS), without pre-reduction of As(V). Glassy carbon was selected as cathode material in the flow cell. An optimum catholyte concentration for simultaneous generation of arsine from As(III) and As(V) was 0.06 mol l{sup -1} H{sub 2}SO{sub 4}. Under the optimized conditions, adequate sensitivity and difference in ratio of slopes of the calibration curves for As(III) and As(V) can be achieved at the electrolytic currents of 0.6 and 1 A. The speciation of inorganic arsenic can be performed by controlling the electrolytic currents, and the concentration of As(III) and As(V) in the sample can be calculated according to the equations of absorbance additivity obtained at two selected electrolytic currents. The calibration curves were linear up to 50 ng ml{sup -1} for both As(III) and As(V) at 0.6 and 1 A. The detection limits of the method were 0.2 and 0.5 ng ml{sup -1} for As(III) and As(V) at 0.6 A, respectively. The relative standard deviations were of 2.1% for 20 ng ml{sup -1} As(III) and 2.5% for 20 ng ml{sup -1} As(V). The method was validated by the analysis of human hair certified reference material and successfully applied to speciation of soluble inorganic arsenic in Chinese medicine.

  18. Speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Li Xun; Jia Jing; Wang Zhenghao

    2006-01-01

    A simple procedure was developed for the speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry (EcHG-AAS), without pre-reduction of As(V). Glassy carbon was selected as cathode material in the flow cell. An optimum catholyte concentration for simultaneous generation of arsine from As(III) and As(V) was 0.06 mol l -1 H 2 SO 4 . Under the optimized conditions, adequate sensitivity and difference in ratio of slopes of the calibration curves for As(III) and As(V) can be achieved at the electrolytic currents of 0.6 and 1 A. The speciation of inorganic arsenic can be performed by controlling the electrolytic currents, and the concentration of As(III) and As(V) in the sample can be calculated according to the equations of absorbance additivity obtained at two selected electrolytic currents. The calibration curves were linear up to 50 ng ml -1 for both As(III) and As(V) at 0.6 and 1 A. The detection limits of the method were 0.2 and 0.5 ng ml -1 for As(III) and As(V) at 0.6 A, respectively. The relative standard deviations were of 2.1% for 20 ng ml -1 As(III) and 2.5% for 20 ng ml -1 As(V). The method was validated by the analysis of human hair certified reference material and successfully applied to speciation of soluble inorganic arsenic in Chinese medicine

  19. Optical Reflectance and Fluorescence for Detecting Nitrogen Needs in Zea mays L.

    Science.gov (United States)

    McMurtrey, J. E.; Middleton, E. M.; Corp. L. A.; Campbell, P. K. Entcheva; Butcher, L. M.; Daughtry, C. S. T.

    2003-01-01

    Nitrogen (N) status in field grown corn (Zea mays L.) was assessed using spectral techniques. Passive reflectance remote sensing and, both passive and active fluorescence sensing methods were investigated. Reflectance and fluorescence methods are reported to detect changes in the primary plant pigments (chlorophylls a and b; carotenoids) in higher plant species. As a general rule, foliar chlorophyll a (Chl a) and chlorophyll b (Chl b) usually exist in approx.3:l ratio. In plants under stress, Chl b content is affected before Chl a reductions occur. For reflectance, a version of the chlorophyll absorption in reflectance index (CARI) method was tested with narrow bands from the Airborne Imaging Spectroradiometer for Applications (ASIA). CARI minimizes the effects of soil background on the signal from green canopies. A modified CARI (MCARI) was used to track total Chl a levels in the red dip of the spectrum from the corn canopy. A second MCARI was used to track the auxiliary plant pigments (Chl b and the carotenoids) in the yellow/orange/red edge part of the reflectance spectrum. The difference between these two MCARI indices detected variations in N levels across the field plot canopies using ASIA data. At the leaf level, ratios of fluorescence emissions in the blue, green, red and far-red wavelengths sensed responses that were associated with the plant pigments, and were indicative of energy transfer in the photosynthetic process. N stressed corn stands could be distinguish from those with optimally applied N with fluorescence emission spectra obtained from individual corn leaves. Both reflectance and fluorescence methods are sensitive in detecting corn N needs and may be especially powerful in monitoring crop conditions if both types of information can be combined.

  20. Fluorescent cadmium sulfide nanoparticles for selective and sensitive detection of toxic pesticides in aqueous medium

    International Nuclear Information System (INIS)

    Walia, Shanka; Acharya, Amitabha

    2014-01-01

    The detection of pesticide residues in ground water, food, or soil samples is extremely important. The currently available laboratory techniques have several drawbacks and needs to be replaced. Fluorescent chemosensors for pesticide detection were reported in the literature, with few reports published on quantum dot-based pesticide sensors, but none of these were focused toward differentiating organophosphorus and organochlorine pesticides specifically. In this respect, glutathione-coated CdS nanoparticles were synthesized and characterized. The TEM studies of the nanoparticles suggested mostly monodispersed spherical particles, with size in the range of 11.5±1 nm. The prepared fluorescent nanoparticles were found to selectively recognize organochlorine pesticide dicofol among all the other pesticides studied, by increasing the fluorescence intensity of the nanoparticles ∼ 2.5 times. Similar studies carried out with organophosphorous pesticide dimethoate did not result any change in the fluorescence intensity of the nanoparticles. Further studies carried out with commercially available pesticide solutions, also confirmed similar results. The TEM, SEM, and DLS studies suggested aggregation of the nanoparticles in the presence of dicofol. Control experiments suggested possible role of both amine and carboxylic acid functional groups of glutathione in the recognition of dicofol. The limit of detection of dicofol was found to be ∼ 55±11 ppb.Graphical AbstractGlutathione-coated CdS nanoparticles selectively recognize organochlorine pesticide dicofol among all the other pesticides studied, by increasing the fluorescence intensity of the nanoparticles. The TEM, SEM, and DLS studies suggested aggregation of the nanoparticles in the presence of dicofol

  1. Fluorescent cadmium sulfide nanoparticles for selective and sensitive detection of toxic pesticides in aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Walia, Shanka; Acharya, Amitabha, E-mail: amitabhachem@gmail.com [CSIR-Institute of Himalayan Bioresource Technology, Biotechnology Division (India)

    2014-12-15

    The detection of pesticide residues in ground water, food, or soil samples is extremely important. The currently available laboratory techniques have several drawbacks and needs to be replaced. Fluorescent chemosensors for pesticide detection were reported in the literature, with few reports published on quantum dot-based pesticide sensors, but none of these were focused toward differentiating organophosphorus and organochlorine pesticides specifically. In this respect, glutathione-coated CdS nanoparticles were synthesized and characterized. The TEM studies of the nanoparticles suggested mostly monodispersed spherical particles, with size in the range of 11.5±1 nm. The prepared fluorescent nanoparticles were found to selectively recognize organochlorine pesticide dicofol among all the other pesticides studied, by increasing the fluorescence intensity of the nanoparticles ∼ 2.5 times. Similar studies carried out with organophosphorous pesticide dimethoate did not result any change in the fluorescence intensity of the nanoparticles. Further studies carried out with commercially available pesticide solutions, also confirmed similar results. The TEM, SEM, and DLS studies suggested aggregation of the nanoparticles in the presence of dicofol. Control experiments suggested possible role of both amine and carboxylic acid functional groups of glutathione in the recognition of dicofol. The limit of detection of dicofol was found to be ∼ 55±11 ppb.Graphical AbstractGlutathione-coated CdS nanoparticles selectively recognize organochlorine pesticide dicofol among all the other pesticides studied, by increasing the fluorescence intensity of the nanoparticles. The TEM, SEM, and DLS studies suggested aggregation of the nanoparticles in the presence of dicofol.

  2. Automatic segmentation of lesions for the computer-assisted detection in fluorescence urology

    Science.gov (United States)

    Kage, Andreas; Legal, Wolfgang; Kelm, Peter; Simon, Jörg; Bergen, Tobias; Münzenmayer, Christian; Benz, Michaela

    2012-03-01

    Bladder cancer is one of the most common cancers in the western world. The diagnosis in Germany is based on the visual inspection of the bladder. This inspection performed with a cystoscope is a challenging task as some kinds of abnormal tissues do not differ much in their appearance from their surrounding healthy tissue. Fluorescence Cystoscopy has the potential to increase the detection rate. A liquid marker introduced into the bladder in advance of the inspection is concentrated in areas with high metabolism. Thus these areas appear as bright "glowing". Unfortunately, the fluorescence image contains besides the glowing of the suspicious lesions no more further visual information like for example the appearance of the blood vessels. A visual judgment of the lesion as well as a precise treatment has to be done using white light illumination. Thereby, the spatial information of the lesion provided by the fluorescence image has to be guessed by the clinical expert. This leads to a time consuming procedure due to many switches between the modalities and increases the risk of mistreatment. We introduce an automatic approach, which detects and segments any suspicious lesion in the fluorescence image automatically once the image was classified as a fluorescence image. The area of the contour of the detected lesion is transferred to the corresponding white light image and provide the clinical expert the spatial information of the lesion. The advantage of this approach is, that the clinical expert gets the spatial and the visual information of the lesion together in one image. This can save time and decrease the risk of an incomplete removal of a malign lesion.

  3. Fluorescent sensors for selective detection of thiols: expanding the intramolecular displacement based mechanism to new chromophores.

    Science.gov (United States)

    Niu, Li-Ya; Zheng, Hai-Rong; Chen, Yu-Zhe; Wu, Li-Zhu; Tung, Chen-Ho; Yang, Qing-Zheng

    2014-03-21

    Biological thiols, including cysteine (Cys), homocystein (Hcy) and glutathione (GSH), play crucial roles in maintaining the appropriate redox status of biological systems. An abnormal level of biothiols is associated with different diseases, therefore, the discrimination between them is of great importance. Herein, we present two fluorescent sensors for selective detection of biothiols based on our recently reported intramolecular displacement mechanism. We expanded this mechanism to commercially available chromophores, 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) and heptamethine cyanine dye IR-780. The sensors operate by undergoing displacement of chloride by thiolate. The amino groups of Cys/Hcy further replace the thiolate to form amino-substituted products, which exhibit dramatically different photophysical properties compared to sulfur-substituted products from the reaction with GSH. NBD-Cl is highly selective towards Cys/Hcy and exhibits significant fluorescence enhancement. IR-780 showed a variation in its fluorescence ratio towards Cys over other thiols. Both of the sensors can be used for live-cell imaging of Cys. The wide applicability of the mechanism may provide a powerful tool for developing novel fluorescent sensors for selective detection of biothiols.

  4. Detection of nitrite based on fluorescent carbon dots by the hydrothermal method with folic acid

    Science.gov (United States)

    Lin, Haitao; Ding, Liyun; Zhang, Bingyu; Huang, Jun

    2018-05-01

    A fluorescent carbon dots probe for the detection of aqueous nitrite was fabricated by a one-pot hydrothermal method, and the transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer were used to study the property of carbon dots. The fluorescent property of carbon dots influenced by the concentration of aqueous nitrite was studied. The interaction between the electron-donating functional groups and the electron-accepting nitrous acid could account for the quenching effect on carbon dots by adding aqueous nitrite. The products of the hydrolysis of aqueous nitrite performed a stronger quenching effect at lower pH. The relationship between the relative fluorescence intensity of carbon dots and the concentration of nitrite was described by the Stern-Volmer equation (I0/I - 1 = 0.046[Q]) with a fine linearity (R2 = 0.99). The carbon dots-based probe provides a convenient method for the detection of nitrite concentration.

  5. Nitrogen-Doped Carbon Quantum Dots as Fluorescent Probes for Sensitive and Selective Detection of Nitrite

    Directory of Open Access Journals (Sweden)

    Zhibiao Feng

    2017-11-01

    Full Text Available Nitrites are the upstream precursors of the carcinogenic nitrosamines, which are widely found in the natural environment and many food products. It is important to develop a simple and sensitive sensor for detecting nitrites. In this work, a fluorescence probe based on nitrogen-doped carbon quantum dots (N-CQDs was developed for the sensitive and selective determination of nitrites. At pH 2, the fluorescence of N-CQDs can be selectively quenched by nitrite due to the fact N-nitroso compounds can be formed in the reaction of amide groups with nitrous acid, which results in fluorescence static quenching. Under optimal conditions, fluorescence intensity quenching upon addition of nitrite gives a satisfactory linear relationship covering the linear range of 0.2–20 μM, and the limit of detection (LOD is 40 nM. Moreover, this method has been successfully applied to the determination of nitrites in tap water, which indicates its great potential for monitoring of nitrites in environmental samples.

  6. Fluorescent nanoscale detection of biotin-streptavidin interaction using near-field scanning optical microscopy

    International Nuclear Information System (INIS)

    Park, Hyun Kyu; Chung, Bong Hyun; Gokarna, Anisha; Hulme, John P; Park, Hyun Gyu

    2008-01-01

    We describe a nanoscale strategy for detecting biotin-streptavidin binding using near-field scanning optical microscopy (NSOM) that exploits the fluorescence properties of single polydiacetylene (PDA) liposomes. NSOM is more useful to observe nanomaterials having optical properties with the help of topological information. We synthesized amine-terminated 10,12-pentacosadiynoic acid (PCDA) monomer (PCDA-NH 2 ) and used this derivatized monomer to prepare PCDA liposomes. PCDA-NH 2 liposomes were immobilized on an aldehyde-functionalized glass surface followed by photopolymerization by using a 254 nm light source. To measure the biotin-streptavidin binding, we conjugated photoactivatable biotin to immobilized PCDA-NH 2 liposomes by UV irradiation (365 nm) and subsequently allowed them to interact with streptavidin. We analyzed the fluorescence using a fluorescence scanner and observed single liposomes using NSOM. The average height and NSOM signal observed in a single liposome after binding were ∼31.3 to 8.5 ± 0.5 nm and 0.37 to 0.16 ± 0.6 kHz, respectively. This approach, which has the advantage of not requiring a fluorescent label, could prove highly beneficial for single molecule detection technology

  7. Assessment of variable fluorescence fluorometry as an approach for rapidly detecting living photoautotrophs in ballast water

    Science.gov (United States)

    First, Matthew R.; Robbins-Wamsley, Stephanie H.; Riley, Scott C.; Drake, Lisa A.

    2018-03-01

    Variable fluorescence fluorometry, an analytical approach that estimates the fluorescence yield of chlorophyll a (F0, a proximal measure of algal concentration) and photochemical yield (FV/FM, an indicator of the physiological status of algae) was evaluated as a means to rapidly assess photoautotrophs. Specifically, it was used to gauge the efficacy of ballast water treatment designed to reduce the transport and delivery of potentially invasive organisms. A phytoflagellate, Tetraselmis spp. (10-12 μm) and mixed communities of ambient protists were examined in both laboratory experiments and large-scale field trials simulating 5-d hold times in mock ballast tanks. In laboratory incubations, ambient organisms held in the dark exhibited declining F0 and FV/FM measurements relative to organisms held under lighted conditions. In field experiments, increases and decreases in F0 and FV/FM over the tank hold time corresponded to those of microscope counts of organisms in two of three trials. In the third trial, concentrations of organisms ≥ 10 and protists) increased while F0 and FV/FM decreased. Rapid and sensitive, variable fluorescence fluorometry is appropriate for detecting changes in organism concentrations and physiological status in samples dominated by microalgae. Changes in the heterotrophic community, which may become more prevalent in light-limited ballast tanks, would not be detected via variable fluorescence fluorometry, however.

  8. Fluorescent molecularly imprinted polymer based on Navicula sp. frustules for optical detection of lysozyme.

    Science.gov (United States)

    Lim, Guat Wei; Lim, Jit Kang; Ahmad, Abdul Latif; Chan, Derek Juinn Chieh

    2016-03-01

    The direct correlation between disease and lysozyme (LYZ) levels in human body fluids makes the sensitive and convenient detection of LYZ the focus of scientific research. Fluorescent molecularly imprinted polymer has emerged as a new alternative for LYZ detection in order to resolve the limitation of immunoassays, which are expensive, unstable, require complex preparation, and are time consuming. In this study, a novel fluorescence molecularly imprinted polymer based on Navicula sp. frustules (FITC-MIP) has been synthesized via post-imprinting treatment for LYZ detection. Navicula sp. frustules were used as supported material because of their unique properties of moderate surface area, reproducibility, and biocompatibility, to address the drawbacks of nanoparticle core material with low adsorption capacity. The FITC acts as recognition signal and optical readout, whereas MIP provides LYZ selectivity. The synthesized FITC-MIP showed a response time as short as 5 min depending on the concentration of LYZ. It is found that the LYZ template can significantly quench the fluorescence intensity of FITC-MIP linearly within a concentration range of 0 to 0.025 mg mL(-1), which is well described by Stern-Volmer equation. The FITC-MIP can selectively and sensitively detect down to 0.0015 mg mL(-1) of LYZ concentration. The excellent sensing performance of FITC-MIP suggests that FITC-MIP is a potential biosensor in clinical diagnosis applications.

  9. Fluorescence in situ hybridisation in chromosome aberration detection in subjects occupationally exposed to ionising radiation

    International Nuclear Information System (INIS)

    Zeljezic, D.; Garaj-Vrhovac, V.

    2005-01-01

    For more than two decades, chromosomal aberration analysis has been used to detect structural chromosomal aberrations as sensitive biodosimeters of occupational exposure to ionising radiation. Its use is also recommended by the World Health Organisation. Changes in chromosome structure detected by that method are considered to be early biomarkers of a possible malignant disease. Aberrations detected by the method are unstable and can be found in the lymphocytes of irradiated personnel only within a limited time after exposure. To detect stable chromosomal aberrations, which persist after exposure, multicolour fluorescent in situ hybridisation has to be used. Using DNA probes labelled with different fluorochromes, it dyes each pair of chromosomes with different colour. Due to the dynamic of unstable aberration formation, chromosomal aberration analysis is more suitable in genome damage assessment of recent exposures. On the other hand, fluorescence in situ hybridisation gives the information on chromosome instability caused by long-term occupational exposure to ionising radiation. Considering the high costs of fluorescence in situ hybridisation and the uncertainty of the result, it should be used in biodosimetry only when it is absolutely necessary.(author)

  10. Smart detection of microRNAs through fluorescence enhancement on a photonic crystal.

    Science.gov (United States)

    Pasquardini, L; Potrich, C; Vaghi, V; Lunelli, L; Frascella, F; Descrovi, E; Pirri, C F; Pederzolli, C

    2016-04-01

    The detection of low abundant biomarkers, such as circulating microRNAs, demands innovative detection methods with increased resolution, sensitivity and specificity. Here, a biofunctional surface was implemented for the selective capture of microRNAs, which were detected through fluorescence enhancement directly on a photonic crystal. To set up the optimal biofunctional surface, epoxy-coated commercially available microscope slides were spotted with specific anti-microRNA probes. The optimal concentration of probe as well as of passivating agent were selected and employed for titrating the microRNA hybridization. Cross-hybridization of different microRNAs was also tested, resulting negligible. Once optimized, the protocol was adapted to the photonic crystal surface, where fluorescent synthetic miR-16 was hybridized and imaged with a dedicated equipment. The photonic crystal consists of a dielectric multilayer patterned with a grating structure. In this way, it is possible to take advantage from both a resonant excitation of fluorophores and an angularly redirection of the emitted radiation. As a result, a significant fluorescence enhancement due to the resonant structure is collected from the patterned photonic crystal with respect to the outer non-structured surface. The dedicated read-out system is compact and based on a wide-field imaging detection, with little or no optical alignment issues, which makes this approach particularly interesting for further development such as for example in microarray-type bioassays. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2018-04-01

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

  12. Improvement of LOD in Fluorescence Detection with Spectrally Nonuniform Background by Optimization of Emission Filtering.

    Science.gov (United States)

    Galievsky, Victor A; Stasheuski, Alexander S; Krylov, Sergey N

    2017-10-17

    The limit-of-detection (LOD) in analytical instruments with fluorescence detection can be improved by reducing noise of optical background. Efficiently reducing optical background noise in systems with spectrally nonuniform background requires complex optimization of an emission filter-the main element of spectral filtration. Here, we introduce a filter-optimization method, which utilizes an expression for the signal-to-noise ratio (SNR) as a function of (i) all noise components (dark, shot, and flicker), (ii) emission spectrum of the analyte, (iii) emission spectrum of the optical background, and (iv) transmittance spectrum of the emission filter. In essence, the noise components and the emission spectra are determined experimentally and substituted into the expression. This leaves a single variable-the transmittance spectrum of the filter-which is optimized numerically by maximizing SNR. Maximizing SNR provides an accurate way of filter optimization, while a previously used approach based on maximizing a signal-to-background ratio (SBR) is the approximation that can lead to much poorer LOD specifically in detection of fluorescently labeled biomolecules. The proposed filter-optimization method will be an indispensable tool for developing new and improving existing fluorescence-detection systems aiming at ultimately low LOD.

  13. Oil leakage detection for electric power equipment based on ultraviolet fluorescence effect

    Science.gov (United States)

    Zhang, Jing; Wang, Jian-hui; Xu, Bin; Huang, Zhi-dong; Huang, Lan-tao

    2018-03-01

    This paper presents a method to detect the oil leakage of high voltage power equipment based on ultraviolet fluorescence effect. The method exploits the principle that the insulating oil has the fluorescent effect under the irradiation of specific ultraviolet light. The emission spectrum of insulating oil under excitation light with different wavelengths is measured and analyzed first. On this basis, a portable oil leakage detective device for high voltage power equipment is designed and developed with a selected 365 nm ultraviolet as the excitation light and the low light level camera as the fluorescence image collector. Then, the feasibility of the proposed method and device in different conditions is experimentally verified in the laboratory environment. Finally, the developed oil leakage detective device is applied to 500 kV Xiamen substation and Quanzhou substation. And the results show that the device can detect the oil leakage of high voltage electrical equipment quickly and conveniently even under the condition of a slight oil leakage especially in the low light environment.

  14. Detection of microbial biofilms on food processing surfaces: hyperspectral fluorescence imaging study

    Science.gov (United States)

    Jun, Won; Kim, Moon S.; Chao, Kaunglin; Lefcourt, Alan M.; Roberts, Michael S.; McNaughton, James L.

    2009-05-01

    We used a portable hyperspectral fluorescence imaging system to evaluate biofilm formations on four types of food processing surface materials including stainless steel, polypropylene used for cutting boards, and household counter top materials such as formica and granite. The objective of this investigation was to determine a minimal number of spectral bands suitable to differentiate microbial biofilm formation from the four background materials typically used during food processing. Ultimately, the resultant spectral information will be used in development of handheld portable imaging devices that can be used as visual aid tools for sanitation and safety inspection (microbial contamination) of the food processing surfaces. Pathogenic E. coli O157:H7 and Salmonella cells were grown in low strength M9 minimal medium on various surfaces at 22 +/- 2 °C for 2 days for biofilm formation. Biofilm autofluorescence under UV excitation (320 to 400 nm) obtained by hyperspectral fluorescence imaging system showed broad emissions in the blue-green regions of the spectrum with emission maxima at approximately 480 nm for both E. coli O157:H7 and Salmonella biofilms. Fluorescence images at 480 nm revealed that for background materials with near-uniform fluorescence responses such as stainless steel and formica cutting board, regardless of the background intensity, biofilm formation can be distinguished. This suggested that a broad spectral band in the blue-green regions can be used for handheld imaging devices for sanitation inspection of stainless, cutting board, and formica surfaces. The non-uniform fluorescence responses of granite make distinctions between biofilm and background difficult. To further investigate potential detection of the biofilm formations on granite surfaces with multispectral approaches, principal component analysis (PCA) was performed using the hyperspectral fluorescence image data. The resultant PCA score images revealed distinct contrast between

  15. Engineering of near infrared fluorescent proteinoid-poly(L-lactic acid) particles for in vivo colon cancer detection.

    Science.gov (United States)

    Kolitz-Domb, Michal; Grinberg, Igor; Corem-Salkmon, Enav; Margel, Shlomo

    2014-08-12

    The use of near-infrared (NIR) fluorescence imaging techniques has gained great interest for early detection of cancer owing to the negligible absorption and autofluorescence of water and other intrinsic biomolecules in this region. The main aim of the present study is to synthesize and characterize novel NIR fluorescent nanoparticles based on proteinoid and PLLA for early detection of colon tumors. The present study describes the synthesis of new proteinoid-PLLA copolymer and the preparation of NIR fluorescent nanoparticles for use in diagnostic detection of colon cancer. These fluorescent nanoparticles were prepared by a self-assembly process in the presence of the NIR dye indocyanine green (ICG), a FDA-approved NIR fluorescent dye. Anti-carcinoembryonic antigen antibody (anti-CEA), a specific tumor targeting ligand, was covalently conjugated to the P(EF-PLLA) nanoparticles through the surface carboxylate groups using the carbodiimide activation method. The P(EF-PLLA) nanoparticles are stable in different conditions, no leakage of the encapsulated dye into PBS containing 4% HSA was detected. The encapsulation of the NIR fluorescent dye within the P(EF-PLLA) nanoparticles improves significantly the photostability of the dye. The fluorescent nanoparticles are non-toxic, and the biodistribution study in a mouse model showed they evacuate from the body over 24 h. Specific colon tumor detection in a chicken embryo model and a mouse model was demonstrated for anti-CEA-conjugated NIR fluorescent P(EF-PLLA) nanoparticles. The results of this study suggest a significant advantage of NIR fluorescence imaging using NIR fluorescent P(EF-PLLA) nanoparticles over colonoscopy. In future work we plan to broaden this study by encapsulating cancer drugs such as paclitaxel and/or doxorubicin, within these biodegradable NIR fluorescent P(EF-PLLA) nanoparticles, for both detection and therapy of colon cancer.

  16. Rapid determination of ampicillin in bovine milk by liquid chromatography with fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Ang, C.Y.W.; Luo, Wenhong [National Center for Toxicological Research, Jefferson, AR (United States)

    1997-01-01

    A rapid and sensitive liquid chromatographic (LC) method was developed for the determination of ampicillin residues in raw bovine milk, processed skim milk, and pasteurized, homogenized whole milk with vitamin D. Milk samples were deproteinized with trichloroacetic acid (TCA) and acetonictrile. After centrifugation, the clear supernatant was reacted with formaldehyde and TCA under heat. The major fluorescent derivative of ampicillin was then determined by reversed-phase LC with fluorescence detection. Average recoveries of ampicillin fortified at 5, 10, and 20 ppb (ng/mL) were all >85% with coefficients of variation <10%. Limits of detection ranged from 0.31 to 0.51 ppb and limits of quantitation, from 0.66 to 1.2 ppb. After appropriate validation, this method should be suitable for rapid analysis of milk for ampicillin residues at the tolerance level of 10 ppb. 16 refs., 4 figs., 3 tabs.

  17. Three-dimensional fluorescent microscopy via simultaneous illumination and detection at multiple planes.

    Science.gov (United States)

    Ma, Qian; Khademhosseinieh, Bahar; Huang, Eric; Qian, Haoliang; Bakowski, Malina A; Troemel, Emily R; Liu, Zhaowei

    2016-08-16

    The conventional optical microscope is an inherently two-dimensional (2D) imaging tool. The objective lens, eyepiece and image sensor are all designed to capture light emitted from a 2D 'object plane'. Existing technologies, such as confocal or light sheet fluorescence microscopy have to utilize mechanical scanning, a time-multiplexing process, to capture a 3D image. In this paper, we present a 3D optical microscopy method based upon simultaneously illuminating and detecting multiple focal planes. This is implemented by adding two diffractive optical elements to modify the illumination and detection optics. We demonstrate that the image quality of this technique is comparable to conventional light sheet fluorescent microscopy with the advantage of the simultaneous imaging of multiple axial planes and reduced number of scans required to image the whole sample volume.

  18. Organic solvents as interferents in arsenic determination by hydride generation atomic absorption spectrometry with flame atomization

    Czech Academy of Sciences Publication Activity Database

    Karadjova, I.B.; Lampugnani, L.; Dědina, Jiří; D'Ulivo, A.; Onor, M.; Tsalev, D.L.

    2006-01-01

    Roč. 61, č. 5 (2006), s. 525-531 ISSN 0584-8547 R&D Projects: GA AV ČR IAA400310507 Institutional research plan: CEZ:AV0Z40310501 Keywords : hydride generation * atomic absorption spectrometry * interferences Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.092, year: 2006

  19. Dielectric barrier discharge plasma atomizer for hydride generation atomic absorption spectrometry-Performance evaluation for selenium

    Czech Academy of Sciences Publication Activity Database

    Duben, Ondřej; Boušek, J.; Dědina, Jiří; Kratzer, Jan

    2015-01-01

    Roč. 111, SEP (2015), s. 57-63 ISSN 0584-8547 Grant - others:GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation-atomic absorption spectrometry * selenium Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.289, year: 2015

  20. COMPREHENSIVE ANALYSIS OF BIOLOGICALLY RELEVANT ARSENICALS BY PH-SELECTIVE HYDRIDE GENERATION-ATOMIC ABSORPTION SPECTROMETRY

    Science.gov (United States)

    A method based on pH-selective generation and separation of arsines is commonly used for analysis of inorganic, methylated, and dimethylated trivalent and pentavalent arsenicals by hydride generation-atomic absorption spectrometry (HG-AAS). We have optimized this method to pe...

  1. Liquid nitrogen-assisted synthesis of fluorescent carbon dots from Blueberry and their performance in Fe3+ detection

    Science.gov (United States)

    Aslandaş, Ayşe Merve; Balcı, Neslihan; Arık, Mustafa; Şakiroğlu, Halis; Onganer, Yavuz; Meral, Kadem

    2015-11-01

    Fluorescent carbon dots (C-dots) were synthesized by a facile method containing liquid N2 treatment and centrifuge processes. The photophysical properties of the C-dots in an aqueous solution were examined at various conditions such as concentration, temperature, pH and excitation wavelength by using UV-vis absorption, fluorescence and time-resolved fluorescence spectroscopies. The C-dots emitted a broad fluorescence between approximately 350-550 nm and their fluorescence was tuned by changing excitation wavelength. The as-prepared C-dots were applied to Fe3+ detection from aqueous solution. Spectroscopic data revealed that the as-prepared C-dots were used to detect Fe3+ in the range of 12.5 μM to 100 μM as a fluorescence sensor.

  2. Naked eye and smartphone applicable detection of toxic mercury ions using fluorescent carbon nanodots

    OpenAIRE

    BAÇ, BURCU; GENÇ, RÜKAN

    2017-01-01

    Chitosan passivated carbon nanodots (C-Dots$_{CHIT})$ were synthesized from expired molasses via a simple and green thermal synthesis procedure. As-synthesized C-Dots were nitrogen-doped (NC-Dots$_{CHIT})$ by posttreatment with liquid ammonia and used as nanoprobes for fluorometric detection of mercury ions (Hg(II)$_{aq.})$. Fluorescence response of NC-Dots$_{CHIT}$ in the presence of mercury was evaluated and compared with that of the polyethylene glycol passivated C-Dots$_{PEG}$. This sensi...

  3. Fundus auto fluorescence and spectral domain ocular coherence tomography in the early detection of chloroquine retinopathy

    OpenAIRE

    Megan B. Goodman; Ari Ziskind

    2015-01-01

    Purpose: To determine the sensitivity of spectral domain ocular coherence tomography (SD-OCT) and fundus auto fluorescence (FAF) images as a screening test to detect early changes in the retina prior to the onset of chloroquine retinopathy. Method: The study was conducted using patients taking chloroquine (CQ), referred by the Rheumatology Department to the Ophthalmology Department at Tygerberg Academic Hospital. Group A consisted of 59 patients on CQ for less than 5 years, and Group B co...

  4. A highly sensitive and selective fluorescent sensor for detection of sulfide anion based on the steric hindrance effect

    Science.gov (United States)

    Chen, Guanfan; Tang, Mengzhuo; Fu, Xiufang; Cheng, Fenmin; Zou, Xianghua; Wang, Jingpei; Zeng, Rongjin

    2018-01-01

    Sulfide anions are not only generated as a byproduct from industrial processes but also as a crucial kind of element in biological systems. Therefore, fluorescent probes for detecting sulfide anion with sensitive and selective characters are highly popular. In this study, we report a highly sensitive and selective fluorescent sensor M1 for detection of sulfide anion based on the steric hindrance effect, where the recognition unit, dinitrobenzenesulfonate ester group is linked to aromatic ortho-position in the porphyrin, and correspondingly the fluorescence of fluorescein is efficiently quenched. Compared with the sensors with recognition unit linked to the other aromatic positions, the fluorescent sensor M1 has a lower fluorescence background. Furthermore, the corresponding fluorescence responses (F/F0) of M1 for mercapto amino-acid GSH, Hcy and Cys, were all far lower than the relative fluorescence ratio F/F0 values for S2-. It means that M1 is sensitive and selective to detection of S2-, and has an anti-disturbance ability to the biologically-relevant thiols, GSH, Hcy and Cys, and has the prospect of application in the exact detection of sulfide anions in living organisms. This approach offers some useful insights for realizing sensitive and selective fluorescent turn-on sensing in the detection assays for other analytes.

  5. Detection of carcinoembryonic antigen using functional magnetic and fluorescent nanoparticles in magnetic separators

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H. Y., E-mail: annetsai@csmu.edu.tw [Chung Shan Medical University, Department of Applied Chemistry (China); Chang, C. Y.; Li, Y. C.; Chu, W. C.; Viswanathan, K.; Bor Fuh, C., E-mail: cbfuh@ncnu.edu.tw [National Chi Nan University, Department of Applied Chemistry (China)

    2011-06-15

    We combined a sandwich immunoassay, anti-CEA/CEA/anti-CEA, with functional magnetic ({approx}80 nm) and fluorescent ({approx}180 nm) nanoparticles in magnetic separators to demonstrate a detection method for carcinoembryonic antigen (CEA). Determination of CEA in serum can be used in clinical diagnosis and monitoring of tumor-related diseases. The CEA concentrations in samples were deduced and determined based on the reference plot using the measured fluorescent intensity of sandwich nanoparticles from the sample. The linear range of CEA detection was from 18 ng/mL to 1.8 pg/mL. The detection limit of CEA was 1.8 pg/mL. In comparison with most other detection methods, this method had advantages of lower detection limit and wider linear range. The recovery was higher than 94%. The CEA concentrations of two serum samples were determined to be 9.0 and 55 ng/mL, which differed by 6.7% (9.6 ng/mL) and 9.1% (50 ng/mL) from the measurements of enzyme-linked immunosorbent assay (ELISA), respectively. The analysis time can be reduced to one third of ELISA. This method has good potential for other biomarker detections and biochemical applications.

  6. Post-PCR detection of nucleic acids using metalloporphyrin labels and time-resolved fluorescence

    International Nuclear Information System (INIS)

    O'Shea, Desmond J.; O'Sullivan, Paul J.; Ponomarev, Gelii V.; Papkovsky, Dmitri B.

    2005-01-01

    Phosphorescent platinum(II)-coproporphyrin label (PtCP) was evaluated in post-PCR detection of nucleic acids by time-resolved fluorescence (TR-F) using three common formats. PtCP-labelled oligonucleotide primers and PtCP-dUTP were incorporated in a PCR to produce labelled amplified target -173 or 305 bp DNA. Alternatively, aminoallyl-dUTP was incorporated in a PCR and the product was subsequently labelled with PtCP. The resulting PCR mixtures containing labelled dsDNA were separated on 1.5% agarose gels and then analysed by ethidium bromide staining and by direct detection of PtCP label on a commercial TR-F plate reader Victor 2 (Perkin Elmer Life Sciences) used in scanning mode. In all cases label incorporation and high yields of amplified DNA were observed. Direct TR-F detection of PtCP-labelled DNA from a gel provided high sensitivity and signal to noise ratio, with limits of detection in the range of 9-22 pg for all three formats. The sensitivity achieved with PtCP label was considerably better than that achieved with ethidium bromide staining (∼1 ng of dsDNA) or with conventional fluorescent label FITC. Neither the FITC label nor ethidium bromide staining interfered with PtCP detection, thus allowing multiplexed detection

  7. Fluorescent probe encapsulated hydrogel microsphere for selective and reversible detection of Hg{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Song, Zhenhu; Wang, Fang; Qiang, Jian; Zhang, Zhijie; Chen, Yahui; Wang, Yong; Zhang, Wei; Chen, Xiaoqiang

    2017-03-15

    We developed a simple and sensitive hydrogel sensor in the form of microspheres by using fluorescence probe encapsulated within a hydrogel matrix for the detection of Hg{sup 2+}. The traditional fluorescence probes suspended in solution are not transportable and recoverable. To overcome these disadvantages, we devised poly(ethylene glycol) diacrylate-based hydrogel microspheres in which fluorescence probe (R19S) was embedded at high density. The functionalized hydrogel microspheres were prepared by combining a microfluidic device with UV light. The hydrogel microspheres-based sensor exhibited good selectivity to Hg{sup 2+} among various metal ions and high sensitivity with a detection limit of 90 nM. Furthermore, after binding with Hg{sup 2+}, the R19S encapsulated hydrogel microspheres can be separated from testing samples easily and treated with the solution containing KI to remove Hg{sup 2+} and realize reusable detection. The current work may offer a new method for Hg{sup 2+} recognition with a more efficient manner.

  8. Highly selective and sensitive fluorescent chemosensor for femtomolar detection of silver ion in aqueous medium

    Directory of Open Access Journals (Sweden)

    Abraham Daniel Arulraj

    2015-12-01

    Full Text Available The chemical sensing for the trace level detection of silver ion in aqueous solution still remains a challenge using simple, rapid, and inexpensive method. We report that thionine can be used as a fluorescent probe for the detection of Ag+ ion. The successive addition of Ag+ ion to the solution containing thionine quenches (turns-off the fluorescence intensity of thionine. Association and quenching constants have been estimated by the Benesi–Hildebrand method and Stern–Volmer plot, respectively. From the plot, the nature of the fluorescence quenching was confirmed as static quenching. An important feature of our chemosensor is high selectivity towards the determination of silver ion in aqueous solution over the other competitive metal ions. The detection limit of the sensor achieved 5 fM for Ag+ ion, which is superior to all previously reported chemosensors. The NMR and FT-IR studies were also carried out to support the complex formation between thionine and Ag+ ion. The practicality of the proposed chemosensor for determination of Ag+ ion was carried in untreated water samples.

  9. A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

    Directory of Open Access Journals (Sweden)

    Stefanie Wolfram

    2014-10-01

    Full Text Available Molecular probes are widely used tools in chemical biology that allow tracing of bioactive metabolites and selective labeling of proteins and other biomacromolecules. A common structural motif for such probes consists of a reporter that can be attached by copper(I-catalyzed 1,2,3-triazole formation between terminal alkynes and azides to a reactive headgroup. Here we introduce the synthesis and application of the new thiazole-based, azide-tagged reporter 4-(3-azidopropoxy-5-(4-bromophenyl-2-(pyridin-2-ylthiazole for fluorescence, UV and mass spectrometry (MS detection. This small fluorescent reporter bears a bromine functionalization facilitating the automated data mining of electrospray ionization MS runs by monitoring for its characteristic isotope signature. We demonstrate the universal utility of the reporter for the detection of an alkyne-modified small molecule by LC–MS and for the visualization of a model protein by in-gel fluorescence. The novel probe advantageously compares with commercially available azide-modified fluorophores and a brominated one. The ease of synthesis, small size, stability, and the universal detection possibilities make it an ideal reporter for activity-based protein profiling and functional metabolic profiling.

  10. Direct and indirect fluorescent detection of tetracyclines using dually emitting carbon dots

    International Nuclear Information System (INIS)

    Qu, Fei; Sun, Zhe; Liu, Dongya; Zhao, Xianen; You, Jinmao

    2016-01-01

    The authors describe dual-emission carbon nanodots containing blue emitters (BE; peak emission at 385 nm under 315 nm excitation) and yellow emitters (YE; peak emission at 530 nm under 365 nm excitation), and how they can be applied to direct and indirect determination of tetracyclines (TCs). The direct detection scheme is based on the finding that tetracycline (TET), oxytetracycline, chlortetracycline and doxycycline quench the two emissions of the carbon dots. While direct determination is rapid and convenient, it cannot differentiate between TCs. The indirect detection scheme, in contrast, is based on the finding that Al (III) ions enhance the fluorescence of the YE in the carbon dots, and that they cause a blue shift in emission. It is, however, known that TET forms a strong complex with Al (III), and this can inhibit the interaction between Al (III) and the YE, so that the fluorescence of YE is not enhanced and blue-shifted by Al (III) in the presence of TET. This finding is exploited in a fluorescence turn-on/off assay for TET that can distinguish TET from other TCs. The linear range of indirect determination for TET extends from 1 nM to 30 μM, and the limit of detection is 0.52 nM. The indirect method was successfully applied to the determination of TET in spiked milk, fish and pork, and recoveries ranged from 91.7 to 102 %. (author)

  11. Light emitting diode, photodiode-based fluorescence detection system for DNA analysis with microchip electrophoresis.

    Science.gov (United States)

    Hall, Gordon H; Glerum, D Moira; Backhouse, Christopher J

    2016-02-01

    Electrophoretic separation of fluorescently end-labeled DNA after a PCR serves as a gold standard in genetic diagnostics. Because of their size and cost, instruments for this type of analysis have had limited market uptake, particularly for point-of-care applications. This might be changed through a higher level of system integration and lower instrument costs that can be realized through the use of LEDs for excitation and photodiodes for detection--if they provide sufficient sensitivity. Here, we demonstrate an optimized microchip electrophoresis instrument using polymeric fluidic chips with fluorescence detection of end-labeled DNA with a LOD of 0.15 nM of Alexa Fluor 532. This represents orders of magnitude improvement over previously reported instruments of this type. We demonstrate the system with an electrophoretic separation of two PCR products and their respective primers. We believe that this is the first LED-induced fluorescence microchip electrophoresis system with photodiode-based detection that could be used for standard applications of PCR and electrophoresis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Blue emitting copper nanoclusters as colorimetric and fluorescent probe for the selective detection of bilirubin

    Science.gov (United States)

    R. S., Aparna; J. S., Anjali Devi; John, Nebu; Abha, K.; S. S., Syamchand; George, Sony

    2018-06-01

    Hurdles to develop point of care diagnostic methods restrict the translation of progress in the health care sector from bench side to bedside. In this article a simple, cost effective fluorescent as well as colorimetric nanosensor was developed for the early and easy detection of hyperbilirubinemia. A stable, water soluble bovine serum albumin stabilised copper nanocluster (BSA CuNC) was used as the fluorescent probe which exhibited strong blue emission (404 nm) upon 330 nm excitation. The fluorescence of the BSA CuNC can be effectively quenched by the addition of bilirubin by the formation of copper-bilirubin complex. Meanwhile the copper-bilirubin complex resulted in an observable colour change from pale violet to green facilitating colorimetric detection. The prepared sensor displayed good selectivity and sensitivity over other co-existing molecules, and can be used for quantifying bilirubin with a detection limit down to 257 fM. Additionally, the as-prepared probe was coated on a paper strip to develop a portable paper strip sensor of bilirubin. Moreover, the method was successfully applied in real sample analysis and obtained promising result.

  13. Detecting thermal phase transitions in corneal stroma by fluorescence micro-imaging analysis

    Science.gov (United States)

    Matteini, P.; Rossi, F.; Ratto, F.; Bruno, I.; Nesi, P.; Pini, R.

    2008-02-01

    Thermal modifications induced in corneal stroma were investigated by the use of fluorescence microscopy. Freshly extracted porcine corneas were immersed for 5 minutes in a water bath at temperatures in the 35-90°C range and stored in formalin. The samples were then sliced in 200-μm-thick transversal sections and analyzed under a stereomicroscope to assess corneal shrinkage. Fluorescence images of the thermally treated corneal samples were acquired using a slow-scan cooled CCD camera, after staining the slices with Indocyanine Green (ICG) fluorescent dye which allowed to detect fluorescence signal from the whole tissue. All measurements were performed using an inverted epifluorescence microscope equipped with a mercury lamp. The thermally-induced modifications to the corneal specimens were evaluated by studying the grey level distribution in the fluorescence images. For each acquired image, Discrete Fourier Transform (DFT) and entropy analyses were performed. The spatial distribution of DFT absolute value indicated the spatial orientation of the lamellar planes, while entropy was used to study the image texture, correlated to the stromal structural transitions. As a result, it was possible to indicate a temperature threshold value (62°C) for high thermal damage, resulting in a disorganization of the lamellar planes and in full agreement with the measured temperature for corneal shrinkage onset. Analysis of the image entropy evidenced five strong modifications in stromal architecture at temperatures of ~45°C, 53°C, 57°C, 66°C, 75°C. The proposed procedure proved to be an effective micro-imaging method capable of detecting subtle changes in corneal tissue subjected to thermal treatment.

  14. Detection of protease activity by fluorescent protein FRET sensors: from computer simulation to live cells

    Science.gov (United States)

    Goryashchenko, Alexander S.; Khrenova, Maria G.; Savitsky, Alexander P.

    2018-04-01

    Förster resonance energy transfer (FRET) sensors are widely used for the detection of protease activity in vitro and in vivo. Usually they consist of a FRET pair connected with a polypeptide linker containing a specific cleavage site for the relevant protease. Use of the fluorescent proteins as components of the FRET pair allows genetic encoding of such sensors and solves the problem of their delivery into live cells and animals. There are several ways to improve the properties of such sensors, mainly to increase FRET efficiency and therefore the dynamic range. One of the ways to achieve this is to use a non-fluorescent chromoprotein as an acceptor. Molecular dynamic simulations may assist in the construction of linker structures connecting donor and acceptor molecules. Estimation of the orientation factor κ 2 can be obtained by methods based on quantum theory and combined quantum mechanics/molecular mechanics approaches. The linker can be structured by hydrophobic interactions, bringing it into a closed conformation that shortens the distance between donor and acceptor and, consequently, increases FRET efficiency. We analyzed the effects of different linker structures on the detection of caspase-3 activity using a non-fluorescent acceptor. Also we have constructed the Tb3+- TagRFP sensor in which a complex of the terbium ion and terbium-binding peptide is used as a donor. This allowed us to use the unique property of lanthanide ions—fluorescence lifetime up to milliseconds—to perform measurements with time delay and exclude the nanosecond-order fluorescence. Using our systems as a starting point, by changing the recognition site in the linker it is possible to perform imaging of different protease activity in vitro or in vivo.

  15. Versatile single-molecule multi-color excitation and detection fluorescence setup for studying biomolecular dynamics

    KAUST Repository

    Sobhy, M. A.

    2011-11-07

    Single-molecule fluorescence imaging is at the forefront of tools applied to study biomolecular dynamics both in vitro and in vivo. The ability of the single-molecule fluorescence microscope to conduct simultaneous multi-color excitation and detection is a key experimental feature that is under continuous development. In this paper, we describe in detail the design and the construction of a sophisticated and versatile multi-color excitation and emission fluorescence instrument for studying biomolecular dynamics at the single-molecule level. The setup is novel, economical and compact, where two inverted microscopes share a laser combiner module with six individual laser sources that extend from 400 to 640 nm. Nonetheless, each microscope can independently and in a flexible manner select the combinations, sequences, and intensities of the excitation wavelengths. This high flexibility is achieved by the replacement of conventional mechanical shutters with acousto-optic tunable filter (AOTF). The use of AOTF provides major advancement by controlling the intensities, duration, and selection of up to eight different wavelengths with microsecond alternation time in a transparent and easy manner for the end user. To our knowledge this is the first time AOTF is applied to wide-field total internal reflection fluorescence (TIRF) microscopy even though it has been commonly used in multi-wavelength confocal microscopy. The laser outputs from the combiner module are coupled to the microscopes by two sets of four single-mode optic fibers in order to allow for the optimization of the TIRF angle for each wavelength independently. The emission is split into two or four spectral channels to allow for the simultaneous detection of up to four different fluorophores of wide selection and using many possible excitation and photoactivation schemes. We demonstrate the performance of this new setup by conducting two-color alternating excitation single-molecule fluorescence resonance energy

  16. Fluorescent quenching immune chromatographic strips with quantum dots and upconversion nanoparticles as fluorescent donors for visual detection of sulfaquinoxaline in foods of animal origin

    International Nuclear Information System (INIS)

    Hu, Gaoshuang; Sheng, Wei; Li, Jingmin; Zhang, Yan; Wang, Junping; Wang, Shuo

    2017-01-01

    In this study, two novel fluorescence quenching immune chromatographic strips (FQICS) were developed to detect sulfaquinoxaline (SQX) in foods of animal origin. These proposed FQICSs were based on fluorescence resonance energy transfer (FRET) from fluorescence donors (quantum dots or upconversion nanoparticles) to fluorescence acceptors (colloidal gold nanoparticles). Compared with traditional colloidal gold-based immune chromatographic strips (ICS), these FQICSs showed positive correlation between the fluorescent signals and the targets, and allowed user to get test results from weak fluorescent signals. The visual detection limits of these two FQICSs were both 1 ng mL −1 in standard solution and 8 μg kg −1 in samples, while the visual detection limit of the colloidal gold-based ICS was 10 ng mL −1 in standard solution and 80 μg kg −1 in samples. Besides, the results we obtained by the use of FQICS showed high agreement with those obtained by the use of commercial ELISA kits, indicating the good accuracy of these strips. As a conclusion, these proposed FQICS based on quantum dots and upconversion nanoparticles can be applied in sensitive, rapid and on-site detection of SQX in foods of animal origin. - Highlights: • Two novel FQICS based on FRET were developed for the first time. • QDs and UCNPs were used as fluorescent donors in the FQICS. • The proposed FQICS showed low LOD compared with traditional ICS. • The proposed FQICS were applied in real samples analysis. • The proposed FQICS were verified by commercial ELISA kits.

  17. Detection of residual rifampicin in urine via fluorescence quenching of gold nanoclusters on paper.

    Science.gov (United States)

    Chatterjee, Krishnendu; Kuo, Chiung Wen; Chen, Ann; Chen, Peilin

    2015-06-26

    Rifampicin or rifampin (R) is a common drug used to treat inactive meningitis, cholestatic pruritus and tuberculosis (TB), and it is generally prescribed for long-term administration under regulated dosages. Constant monitoring of rifampicin is important for controlling the side effects and preventing overdose caused by chronic medication. In this study, we present an easy to use, effective and less costly method for detecting residual rifampicin in urine samples using protein (bovine serum albumin, BSA)-stabilized gold nanoclusters (BSA-Au NCs) adsorbed on a paper substrate in which the concentration of rifampicin in urine can be detected via fluorescence quenching. The intensity of the colorimetric assay performed on the paper-based platforms can be easily captured using a digital camera and subsequently analyzed. The decreased fluorescence intensity of BSA-Au NCs in the presence of rifampicin allows for the sensitive detection of rifampicin in a range from 0.5 to 823 µg/mL. The detection limit for rifampicin was measured as 70 ng/mL. The BSA-Au NCs were immobilized on a wax-printed paper-based platform and used to conduct real-time monitoring of rifampicin in urine. We have developed a robust, cost-effective, and portable point-of-care medical diagnostic platform for the detection of rifampicin in urine based on the ability of rifampicin to quench the fluorescence of immobilized BSA-Au NCs on wax-printed papers. The paper-based assay can be further used for the detection of other specific analytes via surface modification of the BSA in BSA-Au NCs and offers a useful tool for monitoring other diseases.

  18. Fluorescence/depolarization lidar for mid-range stand-off detection of biological agents

    Science.gov (United States)

    Mierczyk, Z.; Kopczyński, K.; Zygmunt, M.; Wojtanowski, J.; Młynczak, J.; Gawlikowski, A.; Młodzianko, A.; Piotrowski, W.; Gietka, A.; Knysak, P.; Drozd, T.; Muzal, M.; Kaszczuk, M.; Ostrowski, R.; Jakubaszek, M.

    2011-06-01

    LIDAR system for real-time standoff detection of bio-agents is presented and preliminary experimental results are discussed. The detection approach is based on two independent physical phenomena: (1) laser induced fluorescence (LIF), (2) depolarization resulting from elastic scattering on non-spherical particles. The device includes three laser sources, two receiving telescopes, depolarization component and spectral signature analyzing spectrograph. It was designed to provide the stand-off detection capability at ranges from 200 m up to several kilometers. The system as a whole forms a mobile platform for vehicle or building installation. Additionally, it's combined with a scanning mechanics and advanced software, which enable to conduct the semi-automatic monitoring of a specified space sector. For fluorescence excitation, 3-rd (355 nm) and 4-th (266 nm) harmonics of Nd:YAG pulsed lasers are used. They emit short (~6 ns) pulses with the repetition rate of 20 Hz. Collecting optics for fluorescence echo detection and spectral content analysis includes 25 mm diameter f/4 Newton telescope, Czerny Turner spectrograph and 32-channel PMT. Depending on the grating applied, the spectral resolution from 20 nm up to 3 nm per channel can be achieved. The system is also equipped with an eye-safe (1.5 μm) Nd:YAG OPO laser for elastic backscattering/depolarization detection. The optical echo signal is collected by Cassegrain telescope with aperture diameter of 12.5 mm. Depolarization detection component based on polarizing beam-splitter serves as the stand-off particle-shape analyzer, which is very valuable in case of non-spherical bio-aerosols sensing.

  19. A fluorescence detection of D-penicillamine based on Cu(2+)-induced fluorescence quenching system of protein-stabilized gold nanoclusters.

    Science.gov (United States)

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

    2015-01-25

    In this contribution, a luminescent gold nanoclusters which were synthesized by bovine serum albumin as novel fluorescent probes were successfully utilized for the determination of D-penicillamine for the first time. Cupric ion was employed to quench the strong fluorescence of the gold nanoclusters, whereas the addition of D-penicillamine caused obvious restoration of fluorescence intensity of the Cu(2+)-gold nanoclusters system. Under optimum conditions, the increment in fluorescence intensity of Cu(2+)-gold nanoclusters system caused by D-penicillamine was linearly proportional to the concentration of D-penicillamine in the range of 2.0×10(-5)-2.39×10(-4) M. The detection limit for D-penicillamine was 5.4×10(-6) M. With the off-on fluorescence signal at 650 nm approaching the near-infrared region, the present sensor for D-penicillamine detection had high sensitivity and low spectral interference. Furthermore, the novel gold nanoclusters-based fluorescent sensor has been applied to the determination of D-penicillamine in real biological samples with satisfactory results. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. A rapid-screening approach to detect and quantify microplastics based on fluorescent tagging with Nile Red

    Science.gov (United States)

    Maes, Thomas; Jessop, Rebecca; Wellner, Nikolaus; Haupt, Karsten; Mayes, Andrew G.

    2017-03-01

    A new approach is presented for analysis of microplastics in environmental samples, based on selective fluorescent staining using Nile Red (NR), followed by density-based extraction and filtration. The dye adsorbs onto plastic surfaces and renders them fluorescent when irradiated with blue light. Fluorescence emission is detected using simple photography through an orange filter. Image-analysis allows fluorescent particles to be identified and counted. Magnified images can be recorded and tiled to cover the whole filter area, allowing particles down to a few micrometres to be detected. The solvatochromic nature of Nile Red also offers the possibility of plastic categorisation based on surface polarity characteristics of identified particles. This article details the development of this staining method and its initial cross-validation by comparison with infrared (IR) microscopy. Microplastics of different sizes could be detected and counted in marine sediment samples. The fluorescence staining identified the same particles as those found by scanning a filter area with IR-microscopy.

  1. New concepts of fluorescent probes for specific detection of DNA sequences: bis-modified oligonucleotides in excimer and exciplex detection.

    Science.gov (United States)

    Gbaj, A; Bichenkova, Ev; Walsh, L; Savage, He; Sardarian, Ar; Etchells, Ll; Gulati, A; Hawisa, S; Douglas, Kt

    2009-12-01

    The detection of single base mismatches in DNA is important for diagnostics, treatment of genetic diseases, and identification of single nucleotide polymorphisms. Highly sensitive, specific assays are needed to investigate genetic samples from patients. The use of a simple fluorescent nucleoside analogue in detection of DNA sequence and point mutations by hybridisation in solution is described in this study. The 5'-bispyrene and 3'-naphthalene oligonucleotide probes form an exciplex on hybridisation to target in water and the 5'-bispyrene oligonucleotide alone is an adequate probe to determine concentration of target present. It was also indicated that this system has a potential to identify mismatches and insertions. The aim of this work was to investigate experimental structures and conditions that permit strong exciplex emission for nucleic acid detectors, and show how such exciplexes can register the presence of mismatches as required in SNP analysis. This study revealed that the hybridisation of 5'-bispyrenyl fluorophore to a DNA target results in formation of a fluorescent probe with high signal intensity change and specificity for detecting a complementary target in a homogeneous system. Detection of SNP mutations using this split-probe system is a highly specific, simple, and accessible method to meet the rigorous requirements of pharmacogenomic studies. Thus, it is possible for the system to act as SNP detectors and it shows promise for future applications in genetic testing.

  2. A cubic boron nitride film-based fluorescent sensor for detecting Hg2+

    Science.gov (United States)

    Liu, W. M.; Zhao, W. W.; Zhang, H. Y.; Wang, P. F.; Chong, Y. M.; Ye, Q.; Zou, Y. S.; Zhang, W. J.; Zapien, J. A.; Bello, I.; Lee, S. T.

    2009-05-01

    Cubic boron nitride (cBN) film-based sensors for detecting Hg2+ ions were developed by surface functionalization with dansyl chloride. To immobilize dansyl chloride, 3-aminopropyltriethoxy silane was modified on hydroxylated cBN surfaces to form an amino-group-terminated self-assembled monolayer. The covalent attachment of the amino groups was confirmed by x-ray photoelectron spectroscopy. The selectivity and sensitivity of the sensors to detect diverse metal cations in ethanol solutions were studied by using fluorescence spectroscopy, revealing a great selectivity to Hg2+ ions. Significantly, the dansyl-chloride-functionalized cBN film sensors were recyclable after the sensing test.

  3. Fluorescence-based bioassays for the detection and evaluation of food materials.

    Science.gov (United States)

    Nishi, Kentaro; Isobe, Shin-Ichiro; Zhu, Yun; Kiyama, Ryoiti

    2015-10-13

    We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based microarrays/biochips, such as antibody/protein microarrays, bead/suspension arrays, capillary/sensor arrays, DNA microarrays/polymerase chain reaction (PCR)-based arrays, glycan/lectin arrays, immunoassay/enzyme-linked immunosorbent assay (ELISA)-based arrays, microfluidic chips and tissue arrays, have been developed and used for the assessment of allergy/poisoning/toxicity, contamination and efficacy/mechanism, and quality control/safety. DNA microarray assays have been used widely for food safety and quality as well as searches for active components. DNA microarray-based gene expression profiling may be useful for such purposes due to its advantages in the evaluation of pathway-based intracellular signaling in response to food materials.

  4. Fluorescence-Based Bioassays for the Detection and Evaluation of Food Materials

    Directory of Open Access Journals (Sweden)

    Kentaro Nishi

    2015-10-01

    Full Text Available We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based microarrays/biochips, such as antibody/protein microarrays, bead/suspension arrays, capillary/sensor arrays, DNA microarrays/polymerase chain reaction (PCR-based arrays, glycan/lectin arrays, immunoassay/enzyme-linked immunosorbent assay (ELISA-based arrays, microfluidic chips and tissue arrays, have been developed and used for the assessment of allergy/poisoning/toxicity, contamination and efficacy/mechanism, and quality control/safety. DNA microarray assays have been used widely for food safety and quality as well as searches for active components. DNA microarray-based gene expression profiling may be useful for such purposes due to its advantages in the evaluation of pathway-based intracellular signaling in response to food materials.

  5. Detection of Colorectal Cancer by a Quantitative Fluorescence Determination of DNA Amplification in Stool

    Directory of Open Access Journals (Sweden)

    Daniele Calistri

    2004-09-01

    Full Text Available DNA amplification of exfoliated cells in stool repre sents an inexpensive and rapid test, but has only 50% to 60% sensitivity. A new quantitative method, calle( fluorescence long DNA, was developed and validate( in our laboratory on stool obtained from 86 patient., with primary colorectal cancer and from 62 health individuals. It consists of the amplification of stoo DNA with fluorescence primers and the quantification of the amplification using a standard curve. Results are arbitrarily expressed in nanograms. The potential of thi new method compared to the conventional approact was analyzed in a subgroup of 94 individuals (51 patients and 38 healthy volunteers. In the presen series, DNA amplification analysis showed a specific ity of 97% and a sensitivity of only 50%. Conversely fluorescence DNA evaluation, using the best cutoff o 25 ng, showed a sensitivity of about 76% and a spec ificity of 93%. Similar sensitivity was observed regard less of Dukes stage, tumor location, and size, thu., also permitting the detection of early-stage tumors The present study seems to indicate that quantitative fluorescence DNA determination in stool successfully identifies colorectal cancer patients with a sensitivity comparable, if not superior, to that of multiple gene analysis but at a lower cost and in a shorter time.

  6. Ratiometric fluorescent detection of chromium(VI) in real samples based on dual emissive carbon dots.

    Science.gov (United States)

    Ma, Yunxia; Chen, Yonglei; Liu, Juanjuan; Han, Yangxia; Ma, Sudai; Chen, Xingguo

    2018-08-01

    As we know, hexavalent chromium (Cr(VI)) was usually used as an additive to improve the color fastness during the printing and dyeing process, and thus posing tremendous threat to our health and living quality. In this work, the dual emissive carbon dots (DECDs) were synthesized through hydrothermal treatment of m-aminophenol and oxalic acid. The obtained DECDs not only exhibited dual emission fluorescence peaks (430 nm, 510 nm) under the single excitation wavelength of 380 nm, but also possessed good water solubility and excellent fluorescence stability. A ratiometric fluorescent method for the determination of Cr(VI) was developed using the DECDs as a probe. Under the optimal conditions, a linear range was obtained from 2 to 300 μM with a limit of detection of 0.4 μM. Furthermore, the proposed ratiometric fluorescent method was applied to the analysis of Cr(VI) in textile, steel, industrial wastewater and chromium residue samples with satisfactory recoveries (88.4-106.8%). Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Selective fluorescence detection of Cu{sup 2+} in aqueous solution and living cells

    Energy Technology Data Exchange (ETDEWEB)

    Saleem, Muhammad; Lee, Ki-Hwan, E-mail: khlee@kongju.ac.kr

    2014-01-15

    A rhodamine B semicarbazide 3 was synthesized by the reaction of rhodamine B acid chloride 2 with hydrazine carboxamide hydrochloride under reflux with triethyl amine in acetonitrile. It was used as selective fluorescent and colorimetric sensor for visual detection of Cu{sup 2+} over competitive ions (Fe{sup 3+},Fe{sup 2+}, Cr{sup 3+}, Cd{sup 2+}, Pb{sup 2+}, Zn{sup 2+}, Hg{sup 2+}, Co{sup 2+}, Ni{sup 2+}, Ca{sup 2+}, Mg{sup 2+}, Ag{sup 2+}, Mn{sup 2+}, Sr{sup 2+}, Cs{sup 2+}, Na{sup +}, K{sup +}, Li{sup +}) in aqueous methanol (1:1, v/v), exhibiting a fast response time, less than few second and a detection limit of 1.6×10{sup −7} mol/L at neutral pH. The proposed sensing system can be successfully applicable for determination of Cu{sup 2+} in waste water samples showing turn on fluorescence response and for further monitoring of intracellular Cu{sup 2+} levels in living cells with high sensitivity and selectivity at micro molar level concentrations using confocal fluorescence spectroscopy. The synthesis of probe 3 was confirmed by {sup 1}H NMR, {sup 13}C NMR and mass spectrometric analysis. -- Highlights: • New chemosensor rhodamine B semicarbazide 3 was synthesized. • Addition of Cu{sup +2} ion into aqueous solution of probe 3 gave visual color changes as well as fluorescent off/on observations. • The proposed spirolactam ring opening mechanism of the synthesized probe triggered by copper ion was revealed by using mass spectrum. • High selectivity and sensitivity of probe 3 towards Cu{sup +2} are excellent enough to detect micromolar level of Cu{sup +2} ion even in aqueous media and living cells.

  8. Native fluorescence detection of biomolecular and pharmaceutical compounds in capillary electrophoresis: detector designs, performance and applications: A review

    NARCIS (Netherlands)

    de Kort, B.J.; de Jong, G.J.; Somsen, G.W.

    2013-01-01

    This review treats the coupling of capillary electrophoresis (CE) with fluorescence detection (Flu) for the analysis of natively fluorescent biomolecular and pharmaceutical compounds. CE-Flu combines the excellent separation efficiency of CE with the high selectivity and sensitivity of Flu. In

  9. Aptamer-based turn-on fluorescent four-branched quaternary ammonium pyrazine probe for selective thrombin detection.

    Science.gov (United States)

    Yan, Shengyong; Huang, Rong; Zhou, Yangyang; Zhang, Ming; Deng, Minggang; Wang, Xiaolin; Weng, Xiaocheng; Zhou, Xiang

    2011-01-28

    In this thrombin detection system, the bright fluorescence of TASPI is almost eliminated by the DNA aptamer TBA (turn-off); however, in the presence of thrombin, it specifically binds to TBA by folding unrestricted TBA into an anti-parallel G-quadruplex structure and then releasing TASPI molecules, resulting in vivid and facile fluorescence recovery (turn-on).

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

    Science.gov (United States)

    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. Copyright © 2015 John Wiley & Sons, Ltd.

  11. Simultaneous fluorescent detection of multiple metal ions based on the DNAzymes and graphene oxide.

    Science.gov (United States)

    Yun, Wen; Wu, Hong; Liu, Xingyan; Fu, Min; Jiang, Jiaolai; Du, Yunfeng; Yang, Lizhu; Huang, Yu

    2017-09-15

    A novel fluorescent detection strategy for simultaneous detection of Cu 2+ , Pb 2+ and Mg 2+ based on DNAzyme branched junction structure with three kinds of DNAzymes and graphene oxide (GO) was presented. Three fluorophores labeled DNA sequences consisted with enzyme-strand (E-DNA) and substrate strand (S-DNA) were annealed to form DNAzyme branched junction structure. In the presence of target metal ion, the DNAzyme was activated to cleave the fluorophore labeled S-DNA. The S-DNA fragments were released and adsorbed onto GO surface to quench the fluorescent signal. The detection limit was calculated to be 1 nM for Cu 2+ , 200 nM for Mg 2+ , and 0.3 nM for Pb 2+ , respectively. This strategy was successfully used for simultaneous detection of Cu 2+ , Mg 2+ and Pb 2+ in human serum. Moreover, it had potential application for simultaneous detection of multiple metal ions in environmental and biological samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Development of narrow-band fluorescence index for the detection of aflatoxin contaminated corn

    Science.gov (United States)

    Yao, Haibo; Hruska, Zuzana; Kincaid, Russell; Ononye, Ambrose; Brown, Robert L.; Bhatnagar, Deepak; Cleveland, Thomas E.

    2011-06-01

    Aflatoxin is produced by the fungus Aspergillus flavus when the fungus invades developing corn kernels. Because of its potent toxicity, the levels of aflatoxin are regulated by the Food and Drug Administration (FDA) in the US, allowing 20 ppb (parts per billion) limits in food, and feed intended for interstate commerce. Currently, aflatoxin detection and quantification methods are based on analytical tests. These tests require the destruction of samples, can be costly and time consuming, and often rely on less than desirable sampling techniques. Thus, the ability to detect aflatoxin in a rapid, non-invasive way is crucial to the corn industry in particular. This paper described how narrow-band fluorescence indices were developed for aflatoxin contamination detection based on single corn kernel samples. The indices were based on two bands extracted from full wavelength fluorescence hyperspectral imagery. The two band results were later applied to two large sample experiments with 25 g and 1 kg of corn per sample. The detection accuracies were 85% and 95% when 100 ppb threshold was used. Since the data acquisition period is significantly lower for several image bands than for full wavelength hyperspectral data, this study would be helpful in the development of real-time detection instrumentation for the corn industry.

  13. Native Fluorescence Detection Methods and Detectors for Naphthalene and/or Other Volatile Organic Compound Vapors

    Science.gov (United States)

    Hug, William F. (Inventor); Bhartia, Rohit (Inventor); Reid, Ray D. (Inventor); Lane, Arthur L. (Inventor)

    2014-01-01

    Naphthalene, benzene, toluene, xylene, and other volatile organic compounds have been identified as serious health hazards. This is especially true for personnel working with JP8 jet fuel and other fuels containing naphthalene as well as other hazardous volatile organic compounds (VOCs). Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to naphthalene or other hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined. The badges employ a new native fluorescence based detection method to identify and differentiate VOCs. The particular focus of some embodiments are the detection and identification of naphthalene while other embodiments are directed to detection and identification of other VOCs like aromatic hydrocarbons such as benzene, toluene, and xylene.

  14. Smart Drug Delivery System-Inspired Enzyme-Linked Immunosorbent Assay Based on Fluorescence Resonance Energy Transfer and Allochroic Effect Induced Dual-Modal Colorimetric and Fluorescent Detection.

    Science.gov (United States)

    Miao, Luyang; Zhu, Chengzhou; Jiao, Lei; Li, He; Du, Dan; Lin, Yuehe; Wei, Qin

    2018-02-06

    Numerous analytical techniques have been undertaken for the detection of protein biomarkers because of their extensive and significant applications in clinical diagnosis, whereas there are few strategies to develop dual-readout immunosensors to achieve more accurate results. To the best of our knowledge, inspired by smart drug delivery system (DDS), a novel pH-responsive modified enzyme-linked immunosorbent assay (ELISA) was innovatively developed for the first time, realizing dual-modal colorimetric and fluorescent detection of cardiac troponin I (cTnI). Curcumin (CUR) was elaborately selected as a reporter molecule, which played the same role of drugs in DDS based on the following considerations: (1) CUR can be used as a kind of pH indicator by the inherited allochroic effect induced by basic pH value; (2) the fluorescence of CUR can be quenched by certain nanocarriers as the acceptor because of the occurrence of fluorescence resonance energy transfer (FRET), while recovered by the stimuli of basic pH value, which can produce "signal-on" fluorescence detection. Three-dimensional MoS 2 nanoflowers (3D-MoS 2 NFs) were employed in immobilizing CUR to constitute a nanoprobe for the determination of cTnI by virtue of good biocompatibility, high absorption capacity, and fluorescence quench efficiency toward CUR. The proposed DDS-inspired ELISA offered dual-modal colorimetric and fluorescent detection of cTnI, thereby meeting the reliable and precise analysis requirements. We believe that the developed dual-readout ELISA will create a new avenue and bring innovative inspirations for biological detections.

  15. Fluorescence detection of pesticides using quantum dot materials – A review

    Energy Technology Data Exchange (ETDEWEB)

    Nsibande, S.A.; Forbes, P.B.C., E-mail: patricia.forbes@up.ac.za

    2016-11-16

    High pesticide use, especially in agriculture, can lead to environmental pollution and potentially adverse health effects. As result, pesticide residues end up in different media, including water and food products, which may serve as direct routes for human exposure. There is thus a continuous drive to develop analytical methods for screening and quantification of these compounds in the different environmental media in which they may occur. Development of quantum dot (QD) based sensors for monitoring pesticides has gained momentum in recent years. QD materials have excellent and unique optical properties and have high fluorescence quantum yields compared to other fluorophores. They have thus been used in numerous studies for the development of probes for organic pollutants. In this paper we specifically review their application as fluorescence probes for pesticide detection in different media including water and in fruits and vegetables. The low detection limits reported demonstrate the potential use of these methods as alternatives to expensive and time-consuming conventional techniques. We also highlight potential limitations that these probes may present when it comes to routine application. Finally we discuss possible future improvements to enhance the selectivity and robustness of these sensors. We note that there is still a need for researchers to develop standardized QD based sensors which could lead to their commercialization and routine application. - Highlights: • Application of quantum dots as fluorescence probes in pesticide detection. • Recognition elements and modification strategies towards selective pesticide detection. • Sensitive detection below regulatory limits in various matrices. • Challenges and possible solutions towards standardization of quantum dot based analytical methods.

  16. Detection of visible and latent fingerprints using micro-X-ray fluorescence elemental imaging.

    Science.gov (United States)

    Worley, Christopher G; Wiltshire, Sara S; Miller, Thomasin C; Havrilla, George J; Majidi, Vahid

    2006-01-01

    Using micro-X-ray fluorescence (MXRF), a novel means of detecting fingerprints was examined in which the prints were imaged based on their elemental composition. MXRF is a nondestructive technique. Although this method requires a priori knowledge about the approximate location of a print, it offers a new and complementary means for detecting fingerprints that are also left pristine for further analysis (including potential DNA extraction) or archiving purposes. Sebaceous fingerprints and those made after perspiring were detected based on elements such as potassium and chlorine present in the print residue. Unique prints were also detected including those containing lotion, saliva, banana, or sunscreen. This proof-of-concept study demonstrates the potential for visualizing fingerprints by MXRF on surfaces that can be problematic using current methods.

  17. Detection of fecal contamination on beef meat surfaces using handheld fluorescence imaging device (HFID)

    Science.gov (United States)

    Oh, Mirae; Lee, Hoonsoo; Cho, Hyunjeong; Moon, Sang-Ho; Kim, Eun-Kyung; Kim, Moon S.

    2016-05-01

    Current meat inspection in slaughter plants, for food safety and quality attributes including potential fecal contamination, is conducted through by visual examination human inspectors. A handheld fluorescence-based imaging device (HFID) was developed to be an assistive tool for human inspectors by highlighting contaminated food and food contact surfaces on a display monitor. It can be used under ambient lighting conditions in food processing plants. Critical components of the imaging device includes four 405-nm 10-W LEDs for fluorescence excitation, a charge-coupled device (CCD) camera, optical filter (670 nm used for this study), and Wi-Fi transmitter for broadcasting real-time video/images to monitoring devices such as smartphone and tablet. This study aimed to investigate the effectiveness of HFID in enhancing visual detection of fecal contamination on red meat, fat, and bone surfaces of beef under varying ambient luminous intensities (0, 10, 30, 50 and 70 foot-candles). Overall, diluted feces on fat, red meat and bone areas of beef surfaces were detectable in the 670-nm single-band fluorescence images when using the HFID under 0 to 50 foot-candle ambient lighting.

  18. Laser-induced fluorescence detection platform for point-of-care testing

    Science.gov (United States)

    Berner, Marcel; Hilbig, Urs; Schubert, Markus B.; Gauglitz, Günter

    2017-08-01

    Point-of-care testing (POCT) devices for continuous low-cost monitoring of critical patient parameters require miniaturized and integrated setups for performing quick high-sensitivity analyses, away from central clinical laboratories. This work presents a novel and promising laser-induced fluorescence platform for measurements in direct optical test formats that leads towards such powerful POCT devices based on fluorescence-labeled immunoassays. Ultimate sensitivity of thin film photodetectors, integrated with microfluidics, and a comprehensive optimization of all system components aim at low-level signal detection in the targeted biosensor application. The setup acquires fluorescence signals from the volume of a microfluidic channel. An innovative sandwiching process forms a flow channel in the microfluidic chips by embedding laser-cut double-sided adhesive tapes. The custom fit of amorphous silicon based photodiode arrays to the geometry of the flow channel enables miniaturization, fully adequate for POCT devices. A free-beam laser excitation with line focus provides excellent alignment stability, allows for easy and reliable swapping of the disposable microfluidic chips, and therewith greatly improves the ease of use of the resulting integrated device. As a proof-of-concept of this novel in-volume measurement approach, the limit of detection for the dye DY636-COOH in pure water as a model fluorophore is examined and found to be 26 nmol l-1 .

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

    Directory of Open Access Journals (Sweden)

    Wenting Li

    2016-01-01

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

  20. Portable hyperspectral fluorescence imaging system for detection of biofilms on stainless steel surfaces

    Science.gov (United States)

    Jun, Won; Lee, Kangjin; Millner, Patricia; Sharma, Manan; Chao, Kuanglin; Kim, Moon S.

    2008-04-01

    A rapid nondestructive technology is needed to detect bacterial contamination on the surfaces of food processing equipment to reduce public health risks. A portable hyperspectral fluorescence imaging system was used to evaluate potential detection of microbial biofilm on stainless steel typically used in the manufacture of food processing equipment. Stainless steel coupons were immersed in bacterium cultures, such as E. coli, Pseudomonas pertucinogena, Erwinia chrysanthemi, and Listeria innocula. Following a 1-week exposure, biofilm formations were assessed using fluorescence imaging. In addition, the effects on biofilm formation from both tryptic soy broth (TSB) and M9 medium with casamino acids (M9C) were examined. TSB grown cells enhance biofilm production compared with M9C-grown cells. Hyperspectral fluorescence images of the biofilm samples, in response to ultraviolet-A (320 to 400 nm) excitation, were acquired from approximately 416 to 700 nm. Visual evaluation of individual images at emission peak wavelengths in the blue revealed the most contrast between biofilms and stainless steel coupons. Two-band ratios compared with the single-band images increased the contrast between the biofilm forming area and stainless steel coupon surfaces. The 444/588 nm ratio images exhibited the greatest contrast between the biofilm formations and stainless coupon surfaces.

  1. Capillary electrophoresis hyphenated with UV-native-laser induced fluorescence detection (CE/UV-native-LIF).

    Science.gov (United States)

    Couderc, François; Ong-Meang, Varravaddheay; Poinsot, Véréna

    2017-01-01

    Native laser-induced fluorescence using UV lasers associated to CE offers now a large related literature, for now 30 years. The main works have been performed using very expensive Ar-ion lasers emitting at 257 and 275 nm. They are not affordable for routine analyses, but have numerous applications such as protein, catecholamine, and indolamine analysis. Some other lasers such as HeCd 325 nm have been used but only for few applications. Diode lasers, emitting at 266 nm, cheaper, are extensively used for the same topics, even if the obtained sensitivity is lower than the one observed using the costly UV-Ar-ion lasers. This review presents various CE or microchips applications and different UV lasers used for the excitation of native fluorescence. We showed that CE/Native UV laser induced fluorescence detection is very sensitive for detection as well as small aromatic biomolecules than proteins containing Trp and Tyr amino acids. Moreover, it is a simple way to analyze biomolecules without derivatization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Fiber optic-based fluorescence detection system for in vivo studies of exogenous chromophore pharmacokinetics

    Science.gov (United States)

    Doiron, Daniel R.; Dunn, J. B.; Mitchell, W. L.; Dalton, Brian K.; Garbo, Greta M.; Warner, Jon A.

    1995-05-01

    The detection and quantification of the concentration of exogenous chromophores in-vivo by their fluorescence is complicated by many physical and geometrical parameters. Measurement of such signals is advantageous in determining the pharmacokinetics of photosensitizers such as those used in photodynamic therapy (PDT) or to assist in the diagnosis of tissue histological state. To overcome these difficulties a ratio based fiber optic contact fluorometer has been developed. This fluorescence detection system (FDS) uses the ratio of the fluorescence emission peak of the exogenous chromophore to that of endogenous chromophores, i.e. autofluorescence, to correct for a variety of parameters affecting the magnitude of the measured signals. By doing so it also minimizes the range of baseline measurements prior to exogenous drug injection, for various tissue types. Design of the FDS and results of its testing in animals and patients using the second generation photosensitizer Tin ethyletiopurpurin (SnET2) are presented. These results support the feasibility and usefulness of the Ratio FDS system.

  3. Selective fluorescence sensors for detection of nitroaniline and metal Ions based on ligand-based luminescent metal-organic frameworks

    International Nuclear Information System (INIS)

    Yu, Zongchao; Wang, Fengqin; Lin, Xiangyi; Wang, Chengmiao; Fu, Yiyuan; Wang, Xiaojun; Zhao, Yongnan; Li, Guodong

    2015-01-01

    Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)–based metal-organic frameworks, Zn_3L_3(DMF)_2 (1) and Zn_3L_3(DMA)_2(H_2O)_3 (2) (L=4,4′-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe"3"+ and Al"3"+ by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significant fluorescence quenching effect for Fe"3"+. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity. - Graphical abstract: Two MOFs have been selected as the fluorescence sensing materials for selectively sensing mitroaromatic compounds and metal ions. The high selectivity makes them promising fluorescence sensors for detecting and recognizing nitroaniline and Fe"3"+ or Al"3"+.

  4. Development of a new detection device using a glass clip emitting infrared fluorescence for laparoscopic surgery of gastric cancer

    International Nuclear Information System (INIS)

    Inada, Shunko Albano; Mori, Kensaku; Fuchi, Shingo; Hasegawa, Junichi; Misawa, Kazunari; Nakanishi, Hayao

    2015-01-01

    In conventional method, to identify location of the tumor intraperitoneally for extirpation of the gastric cancer, charcoal ink is injected around the primary tumor. However, in the time of laparoscopic operation, it is difficult to estimate specific site of primary tumor. In this study we developed a glass phosphors was realized with Yb 3+ , Nd 3+ doped to Bi 2 O 3 -B 2 O 3 based glasses, which have central emission wavelength of 1020 nm and 100 nm of FWHM. Using this glass phosphor, we developed a fluorescent clip and the laparoscopic fluorescent detection system for clip-derived near-infrared light. To evaluated clinical performance of a fluorescent clip and the laparoscopic detection system, we used resected stomach from the patients. Fluorescent clip was fixed on the gastric mucosa, and an excitation light (wavelength: 808nm) was irradiated from outside of stomach for detection of fluorescent through stomach wall. As a result, fluorescent emission from the clip was successfully detected. These results indicate that the glass fluorescent clip in combination with laparoscopic detection system is a very useful method to identify the exact location of the primary gastric cancer. (paper)

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

    Science.gov (United States)

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

    2016-01-19

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

  6. Fluorescence-based methods for the detection of pressure-induced spore germination and inactivation

    Science.gov (United States)

    Baier, Daniel; Reineke, Kai; Doehner, Isabel; Mathys, Alexander; Knorr, Dietrich

    2011-03-01

    The application of high pressure (HP) provides an opportunity for the non-thermal preservation of high-quality foods, whereas highly resistant bacterial endospores play an important role. It is known that the germination of spores can be initiated by the application of HP. Moreover, the resistance properties of spores are highly dependent on their physiological states, which are passed through during the germination. To distinguish between different physiological states and to detect the amount of germinated spores after HP treatments, two fluorescence-based methods were applied. A flow cytometric method using a double staining with SYTO 16 as an indicator for germination and propidium iodide as an indicator for membrane damage was used to detect different physiological states of the spores. During the first step of germination, the spore-specific dipicolinic acid (DPA) is released [P. Setlow, Spore germination, Curr. Opin. Microbiol. 6 (2003), pp. 550-556]. DPA reacts with added terbium to form a distinctive fluorescent complex. After measuring the fluorescence intensity at 270 nm excitation wavelength in a fluorescence spectrophotometer, the amount of germinated spores can be determined. Spores of Bacillus subtilis were treated at pressures from 150 to 600 MPa and temperatures from 37 °C to 60 °C in 0.05 M ACES buffer solution (pH 7) for dwell times of up to 2 h. During the HP treatments, inactivation up to 2log 10 cycles and thermal sensitive populations up to 4log 10 cycles could be detected by plate counts. With an increasing number of thermal sensitive spores, an increased proportion of spores in germinated states was detected by flow cytometry. Also the released amount of DPA increased during the dwell times. Moreover, a clear pressure-temperature-time-dependency was shown by screening different conditions. The fluorescence-based measurement of the released DPA can provide the opportunity of an online monitoring of the germination of spores under HP inside

  7. Self-interference fluorescence microscopy with three-phase detection for depth-resolved confocal epi-fluorescence imaging.

    Science.gov (United States)

    Braaf, Boy; de Boer, Johannes F

    2017-03-20

    Three-dimensional confocal fluorescence imaging of in vivo tissues is challenging due to sample motion and limited imaging speeds. In this paper a novel method is therefore presented for scanning confocal epi-fluorescence microscopy with instantaneous depth-sensing based on self-interference fluorescence microscopy (SIFM). A tabletop epi-fluorescence SIFM setup was constructed with an annular phase plate in the emission path to create a spectral self-interference signal that is phase-dependent on the axial position of a fluorescent sample. A Mach-Zehnder interferometer based on a 3 × 3 fiber-coupler was developed for a sensitive phase analysis of the SIFM signal with three photon-counter detectors instead of a spectrometer. The Mach-Zehnder interferometer created three intensity signals that alternately oscillated as a function of the SIFM spectral phase and therefore encoded directly for the axial sample position. Controlled axial translation of fluorescent microsphere layers showed a linear dependence of the SIFM spectral phase with sample depth over axial image ranges of 500 µm and 80 µm (3.9 × Rayleigh range) for 4 × and 10 × microscope objectives respectively. In addition, SIFM was in good agreement with optical coherence tomography depth measurements on a sample with indocyanine green dye filled capillaries placed at multiple depths. High-resolution SIFM imaging applications are demonstrated for fluorescence angiography on a dye-filled capillary blood vessel phantom and for autofluorescence imaging on an ex vivo fly eye.

  8. Determination of Ivermectin in Medicated Feeds by Liquid Chromatography with Fluorescence Detection

    Science.gov (United States)

    2013-01-01

    A labour- and time-effective analytical procedure for determination of ivermectin in medicated feed at recommended level of 2.0 mg kg−1 has been developed and validated. The analyte was extracted from grinded feed samples with acetonitrile and derivatisated with N-methylimidazole and trifluoracetic anhydride. The fluorescent derivatives were analysed by liquid chromatography method using C8 column. The isocratic conditions using acetonitrile, methanol, water, and tetrahydrofuran were applied. Fluorescence detection was performed at 365 nm (excitation) and 475 nm (emission) wavelengths. The total analysis time was 10 min. The validation results of the method (within-laboratory reproducibility 4.0% CV, mean recovery 100.1%) confirm the appropriate precision and accuracy of the developed method. PMID:24453835

  9. A rhodamine B-based fluorescent sensor toward highly selective mercury (II) ions detection.

    Science.gov (United States)

    Jiao, Yang; Zhang, Lei; Zhou, Peng

    2016-04-01

    This work presented the design, syntheses and photophysical properties of a rhodamine B-based fluorescence probe, which exhibited a sensitive and selective recognition towards mercury (II). The chemosensor RA (Rhodamine- amide- derivative) contained a 5-aminoisophthalic acid diethyl ester and a rhodamine group, and the property of spirolactone of this chemosensor RA was detected by X-ray crystal structure analyses. Chemosensor RA afforded turn-on fluorescence enhancement and displayed high brightness for Hg(2+), which leaded to the opening of the spirolactone ring and consequently caused the appearance of strong absorption at visible range, moreover, the obvious and characteristic color changed from colorless to pink was observed. We envisioned that the chemosensor RA exhibited a considerable specificity with two mercury (II) ions which was attributed to the open of spirolactone over other interference metal ions. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. A conformation-induced fluorescence method for microRNA detection

    DEFF Research Database (Denmark)

    Aw, Sherry S; Tang, Melissa Xm; Teo, Yin Nah

    2016-01-01

    and quantify microRNAs may aid research into novel aspects of microRNA biology and contribute to the development of diagnostics. By introducing an additional stem loop into the fluorescent RNA Spinach and altering its 3' and 5' ends, we have generated a new RNA, Pandan, that functions as the basis for a micro......MicroRNAs play important roles in a large variety of biological systems and processes through their regulation of target mRNA expression, and show promise as clinical biomarkers. However, their small size presents challenges for tagging or direct detection. Innovation in techniques to sense......RNA sensor. Pandan contains two sequence-variable stem loops that encode complementary sequence for a target microRNA of interest. In its sensor form, it requires the binding of a target microRNA in order to reconstitute the RNA scaffold for fluorophore binding and fluorescence. Binding of the target micro...

  11. Label-free tungsten disulfide quantum dots as a fluorescent sensing platform for highly efficient detection of copper (II) ions

    International Nuclear Information System (INIS)

    Zhao Xuan; He Da-Wei; Wang Yong-Sheng; Hu Yin; Fu Chen; Li Xue

    2017-01-01

    A fluorescent probe for the sensitive and selective determination of copper ion (Cu 2+ ) is presented. It is based on the use of tungsten disulfide quantum dots (WS 2 QDs) which is independent of the pH of solution and emits strong blue fluorescence. Copper ions could cause aggregation of the WS 2 QDs and lead to fluorescence quenching of WS 2 QDs. The change of fluorescence intensity is proportional to the concentration of Cu 2+ , and the limit of detection is 0.4 μM. The fluorescent probe is highly selective for Cu 2+ over some potentially interfering ions. These results indicate that WS 2 QDs, as a fluorescent sensing platform, can meet the selective requirements for biomedical and environmental application. (paper)

  12. Intrinsic Tryptophan Fluorescence in the Detection and Analysis of Proteins: A Focus on Förster Resonance Energy Transfer Techniques

    Directory of Open Access Journals (Sweden)

    Amar B. T. Ghisaidoobe

    2014-12-01

    Full Text Available F resonance energy transfer (FRET occurs when the distance between a donor fluorophore and an acceptor is within 10 nm, and its application often necessitates fluorescent labeling of biological targets. However, covalent modification of biomolecules can inadvertently give rise to conformational and/or functional changes. This review describes the application of intrinsic protein fluorescence, predominantly derived from tryptophan (\\(\\uplambda_{\\textsc{ex}}\\sim\\ nm, \\(\\uplambda_{\\textsc{em}}\\sim\\ 350 nm, in protein-related research and mainly focuses on label-free FRET techniques. In terms of wavelength and intensity, tryptophan fluorescence is strongly influenced by its (or the proteinlocal environment, which, in addition to fluorescence quenching, has been applied to study protein conformational changes. Intrinsic F resonance energy transfer (iFRET, a recently developed technique, utilizes the intrinsic fluorescence of tryptophan in conjunction with target-specific fluorescent probes as FRET donors and acceptors, respectively, for real time detection of native proteins.

  13. SERS and fluorescence-based ultrasensitive detection of mercury in water.

    Science.gov (United States)

    Makam, Pandeeswar; Shilpa, Rohilla; Kandjani, Ahmad Esmaielzadeh; Periasamy, Selvakannan R; Sabri, Ylias Mohammad; Madhu, Chilakapati; Bhargava, Suresh Kumar; Govindaraju, Thimmaiah

    2018-02-15

    The development of reliable and ultrasensitive detection marker for mercury ions (Hg 2+ ) in drinking water is of great interest for toxicology assessment, environmental protection and human health. Although many Hg 2+ detection methods have been developed, only few offer sensitivities below 1pM. Herein, we describe a simple histidine (H) conjugated perylene diimide (PDI) bolaamphiphile (HPH) as a dual-responsive optical marker to develop highly selective and sensitive probe as visible (sol-to-gel transformation), fluorescence and SERS-based Hg 2+ sensor platform in the water. Remarkably, HPH as a SERS marker supported on Au deposited monodispersed nanospheres monolayers (Au-MNM) of polystyrene offers an unprecedented selectivity and the best ever reported detection limit (LOD) of 60 attomolar (aM, 0.01 parts-per-quadrillion (ppq)) for Hg 2+ in water. This is ten orders of magnitude lower than the United States Environmental Protection Agency (USEPA) tolerance limit of Hg 2+ in drinking water (10nM, 2 ppb). This simple and effective design principle of host-guest interactions driven fluorescence and SERS-based detection may inspire the future molecular engineering strategies for the development of ultrasensitive toxic analyte sensor platforms. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Nitrogen-doped graphene quantum dots-based fluorescence molecularly imprinted sensor for thiacloprid detection.

    Science.gov (United States)

    Liu, Yang; Cao, Nan; Gui, Wenying; Ma, Qiang

    2018-06-01

    In this paper, a test strip-based sensor was developed for thiacloprid quantitative detection based on PDA molecularly imprinted polymer (MIP) and nitrogen-doped graphene quantum dots (N-GQDs). Thiacloprid is a new type of nicotine insecticide, which can block the normal neurotransmitter delivery process in insects. In the sensing system, N-GQDs were immersed into filter paper at first. Then, dopamine (DA) with thiacloprid can be self-polymerized on test strip surface to form the uniform PDA film. After removed thiacloprid template, the established poly dopamine (PDA) MIP can selectively recognize thiacloprid. As a result, captured thiacloprid can enhance the fluorescence intensity of N-GQDs into the test strip. As a result, the fluorescence intensity of N-GQDs can be linearly related within a certain range of thiacloprid concentration. Under the optimum conditions, the proposed sensor for thiacloprid detection exhibited a linear ranging from 0.1 mg/L to 10 mg/L with a low detection limit of 0.03 mg/L. The N-GQDs based test strip-based sensor for thiaclopridis reported for the first time. The sensing system has high selectivity to thiacloprid and provides new opportunities in the pesticide detection. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. A sensitive fluorescence quenching method for the detection of tartrazine with acriflavine in soft drinks.

    Science.gov (United States)

    Yang, Huan; Ran, Guihua; Yan, Jingjing; Zhang, Hui; Hu, Xiaoli

    2018-03-01

    In this work, a simple, rapid, sensitive, selective spectrofluorimetric method was applied to detect tartrazine. The fluorescence of acriflavine could be efficiently quenched by tartrazine. The method manifested real time response as well as presented satisfied linear relationship to tartrazine. The linear response range of tartrazine (R 2 = 0.9995) was from 0.056 to 5 μmol L -1 . The detection limit (3σ/k) was 0.017 μmol L -1 , indicating that this method could be applied to detect traces of tartrazine. The accuracy and precision of the method was further assured by recovery studies via a standard addition method, with percentage recoveries in the range of 96.0% to 103.0%. Moreover, a quenching mechanism was investigated systematically by the linear plots at varying temperatures based on the Stern-Volmer equation, fluorescence lifetime and UV-visible absorption spectra, all of which proved to be static quenching. This sensitive, selective assay possessed a great application prospect for the food industry owing to its simplicity and rapidity for the detection of tartrazine. Copyright © 2017 John Wiley & Sons, Ltd.

  16. Development and application of a fluorescence protein microarray for detecting serum alpha-fetoprotein in patients with hepatocellular carcinoma.

    Science.gov (United States)

    Zhang, Aiying; Yin, Chengzeng; Wang, Zhenshun; Zhang, Yonghong; Zhao, Yuanshun; Li, Ang; Sun, Huanqin; Lin, Dongdong; Li, Ning

    2016-12-01

    Objective To develop a simple, effective, time-saving and low-cost fluorescence protein microarray method for detecting serum alpha-fetoprotein (AFP) in patients with hepatocellular carcinoma (HCC). Method Non-contact piezoelectric print techniques were applied to fluorescence protein microarray to reduce the cost of prey antibody. Serum samples from patients with HCC and healthy control subjects were collected and evaluated for the presence of AFP using a novel fluorescence protein microarray. To validate the fluorescence protein microarray, serum samples were tested for AFP using an enzyme-linked immunosorbent assay (ELISA). Results A total of 110 serum samples from patients with HCC ( n = 65) and healthy control subjects ( n = 45) were analysed. When the AFP cut-off value was set at 20 ng/ml, the fluorescence protein microarray had a sensitivity of 91.67% and a specificity of 93.24% for detecting serum AFP. Serum AFP quantified via fluorescence protein microarray had a similar diagnostic performance compared with ELISA in distinguishing patients with HCC from healthy control subjects (area under receiver operating characteristic curve: 0.906 for fluorescence protein microarray; 0.880 for ELISA). Conclusion A fluorescence protein microarray method was developed for detecting serum AFP in patients with HCC.

  17. Development of graphite carbon nitride based fluorescent immune sensor for detection of alpha fetoprotein

    Science.gov (United States)

    Li, Yike; Dong, Lingyu; Wang, Xiangfeng; Liu, Yuan; Liu, Hailing; Xie, Mengxia

    2018-05-01

    A novel fluorescent immunosensor for determination of alpha fetoprotein (AFP) in serum samples has been developed based on the nano graphite carbon nitride (g-C3N4) as fluorophore and immunomagnetic beads (MBs) as separation material. The bulk g-C3N4 was obtained by thermal polymerization of melamine, and then carboxylated and exfoliated to acquire the carboxylated nano g-C3N4 (c-n-g-C3N4), which has been characterized and the results showed that it had excellent fluorescent properties. The antibodies of AFP (Ab1, Ab2) were conjugated to the MBs and the c-n-g-C3N4, respectively. In assay of AFP detection, the magnetic part of the immunosensor, MBs-Ab1, would form the sandwich type complex with the signal part of the sensor, c-n-g-C3N4-Ab2. The developed immunosensor could simplify the process of separation due to the MBs. The results illustrated that proposed approach held a good linearity between the fluorescence intensity of the sensor and the AFP concentration ranging from 5-600 ng/mL with the limit of detection as low as 0.43 ng/mL, and its spiking recoveries ranged from 98.2% to 105.9% with RSD from 2.1% to 3.5%. The fabricated fluorescent immunosensor possesses the merits of good sensitivity, excellent selectivity, high biocompatibility and low cost, and the results provide a novel clue to develop immunosensor for determination of the biomarkers in complex matrices.

  18. A novel fluorescent DNA sensor for ultrasensitive detection of Helicobacter pylori.

    Science.gov (United States)

    Liu, Ziping; Su, Xingguang

    2017-01-15

    In this work, a novel fluorescent DNA sensor for ultrasensitive detection of Helicobacter pylori (H. pylori) DNA was developed. This strategy took advantage of DNA hybridization between single-stranded DNA (ssDNA, which had been designed as an aptamer specific for H. pylori DNA) and the complementary target H. pylori DNA, and the feature that ssDNA bound to graphene oxide (GO) with significantly higher affinity than double-stranded DNA (dsDNA). ssDNA were firstly covalent conjugated with CuInS 2 quantum dots (QDs) by reaction between the carboxy group of QDs and amino group modified ssDNA, forming ssDNA-QDs genosensor. In the absence of the complementary target H. pylori DNA, GO could adsorb ssDNA-QDs DNA sensor and efficiently quench the fluorescence of ssDNA-QDs. While the complementary target H. pylori DNA was introduced, the ssDNA-QDs preferentially bound with the H. pylori DNA. The formation of dsDNA would alter the conformation of ssDNA and disturb the interaction between ssDNA and GO. Thus, the dsDNA-QDs/GO system exhibited a stronger fluorescence emission than that of the ssDNA-QDs/GO system. Under the optimized conditions, a linear correlation was established between the fluorescence intensity ratio I/I 0 and the concentration of H. pylori DNA in the range of 1.25-875pmolL -1 with a detection limit of 0.46pmolL -1 . The proposed method was applied to the determination of H. pylori DNA sequence in milk samples with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Quantification of confocal fluorescence microscopy for the detection of cervical intraepithelial neoplasia.

    Science.gov (United States)

    Sheikhzadeh, Fahime; Ward, Rabab K; Carraro, Anita; Chen, Zhao Yang; van Niekerk, Dirk; Miller, Dianne; Ehlen, Tom; MacAulay, Calum E; Follen, Michele; Lane, Pierre M; Guillaud, Martial

    2015-10-24

    Cervical cancer remains a major health problem, especially in developing countries. Colposcopic examination is used to detect high-grade lesions in patients with a history of abnormal pap smears. New technologies are needed to improve the sensitivity and specificity of this technique. We propose to test the potential of fluorescence confocal microscopy to identify high-grade lesions. We examined the quantification of ex vivo confocal fluorescence microscopy to differentiate among normal cervical tissue, low-grade Cervical Intraepithelial Neoplasia (CIN), and high-grade CIN. We sought to (1) quantify nuclear morphology and tissue architecture features by analyzing images of cervical biopsies; and (2) determine the accuracy of high-grade CIN detection via confocal microscopy relative to the accuracy of detection by colposcopic impression. Forty-six biopsies obtained from colposcopically normal and abnormal cervical sites were evaluated. Confocal images were acquired at different depths from the epithelial surface and histological images were analyzed using in-house software. The features calculated from the confocal images compared well with those features obtained from the histological images and histopathological reviews of the specimens (obtained by a gynecologic pathologist). The correlations between two of these features (the nuclear-cytoplasmic ratio and the average of three nearest Delaunay-neighbors distance) and the grade of dysplasia were higher than that of colposcopic impression. The sensitivity of detecting high-grade dysplasia by analysing images collected at the surface of the epithelium, and at 15 and 30 μm below the epithelial surface were respectively 100, 100, and 92 %. Quantitative analysis of confocal fluorescence images showed its capacity for discriminating high-grade CIN lesions vs. low-grade CIN lesions and normal tissues, at different depth of imaging. This approach could be used to help clinicians identify high-grade CIN in clinical

  20. A novel approach for the detection of early gastric cancer: fluorescence spectroscopy of gastric juice.

    Science.gov (United States)

    Deng, Kai; Zhou, Li Ya; Lin, San Ren; Li, Yuan; Chen, Mo; Geng, Qiu Ming; Li, Yu Wen

    2013-06-01

    This study aimed to investigate the efficacy of fluorescence spectroscopy of gastric juice for early gastric cancer (EGC) screening. Gastric juice was collected from 101 participants who underwent endoscopy in the Outpatient Endoscopy Center of Peking University Third Hospital. The participants were divided into three groups: the normal mucosa or chronic non-atrophic gastritis (NM-CNAG) group (n = 35), advanced gastric cancer (AGC) group (n = 33) and EGC group (n = 33). Fluorescence spectroscopic analysis was performed in all the gastric juice samples and the maximum fluorescence intensity of the first peak (P1 FI) was measured. The mean fluorescence intensity of P1 FI of gastric juice in AGC (92.1 ± 10.7) and EGC (90.8 ± 12.0) groups was significantly higher than that in the NM-CNAG group (55.7 ± 7.5) (AGC vs NM-CNAG, P = 0.006 and EGC vs NM-CNAG, P = 0.015, respectively). The areas under the receiver operating characteristic curves for the detection of AGC and EGC were 0.681 (95% confidence interval [CI] 0.553-0.810, P = 0.010) and 0.655 (95% CI 0.522-0.787, P = 0.028). With the P1 FI of ≥47.7, the sensitivity, specificity and accuracy for detecting EGC were 69.7%, 57.1% and 63.2%, respectively. The enhancement of P1 FI of gastric juice occurs at the early stage of gastric cancer. Fluorescence spectroscopy of gastric juice may be used as a novel screening tool for the early detection of gastric cancer. © 2013 The Authors. Journal of Digestive Diseases © 2013 Wiley Publishing Asia Pty Ltd and Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine.

  1. Application of silver nanoparticles in the detection of SYBR Green I by surface enhanced Raman and surface-enhanced fluorescence

    Science.gov (United States)

    Guo, Wei; Wu, Jian; Wang, Chunyan; Zhang, Tian; Chen, Tao

    2018-05-01

    Silver nanomaterials have remarkable application in biomedical detection due to their unique surface plasmon resonance (SPR) characteristics. It can be used for surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF). Current research elaborates a technique for improvement of SYBR Green I detection obtained from surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) by silver nanoparticles with the average size about 70 nm. Primarily, SYBR Green I is an important fluorescent dye used in polymerase chain reaction (PCR). It is found that both Raman and fluorescence can be used for detection of this dye. Furthermore, the enhanced efficiency of the Raman and fluorescence by SERS and SEF is observed in this study, the enhancement factor for Raman signals is 3.2 × 103, and the fluorescence intensity bincreased two times by SEF. The quantitative detection of SYBR Green I by SERS and SEF can be achieved. The present work can be used to improve the detection of SYBR Green I by SERS and SEF. It would also be employed for high-sensitive detection of other materials in the future.

  2. Fluorescence detection of single molecules using pulsed near-field optical excitation and time correlated photon counting

    International Nuclear Information System (INIS)

    Ambrose, W.P.; Goodwin, P.M.; Martin, J.C.; Keller, R.A.

    1994-01-01

    Pulsed excitation, time correlated single photon counting and time gated detection are used in near-field optical microscopy to enhance fluorescence images and measure the fluorescence lifetimes of single molecules of Rhodamine 6G on silica surfaces. Time gated detection is used to reject prompt scattered background and to improve the image signal to noise ratio. The excited state lifetime of a single Rhodamine 6G molecule is found to depend on the position of the near-field probe. We attribute the lifetime variations to spontaneous emission rate alterations by the fluorescence reflected from and quenching by the aluminum coated probe

  3. A Graphene Oxide-Based Fluorescent Aptasensor for the Turn-on Detection of CCRF-CEM.

    Science.gov (United States)

    Tan, Jie; Lai, Zongqiang; Zhong, Liping; Zhang, Zhenghua; Zheng, Rong; Su, Jing; Huang, Yong; Huang, Panpan; Song, Hui; Yang, Nuo; Zhou, Sufang; Zhao, Yongxiang

    2018-04-01

    A convenient, low-cost, and highly sensitive fluorescent aptasensor for detection of leukemia has been developed based on graphene oxide-aptamer complex (GO-apt). Graphene oxide (GO) can absorb carboxyfluorescein-labeled Sgc8 aptamer (FAM-apt) by π-π stacking and quench the fluorescence through fluorescence resonance energy transfer (FRET). In the absence of Sgc8 target cell CCRF-CEM, the fluorescence is almost all quenched. Conversely, when the CCRF-CEM cells are added, the quenched fluorescence can be recovered rapidly and significantly. Therefore, based on the change of fluorescence signals, we can detect the number of CCRF-CEM cells in a wide range from 1 × 10 2 to 1 × 10 7  cells/mL with a limit of detection (LOD) of 10 cells/mL. Therefore, this strategy of graphene oxide-based fluorescent aptasensor may be promising for the detection of cancer.

  4. Alpha-fetoprotein detection by using a localized surface plasmon coupled fluorescence fiber-optic biosensor

    Science.gov (United States)

    Chang, Ying-Feng; Chen, Ran-Chou; Li, Ying-Chang; Yu, Chih-Jen; Hsieh, Bao-Yu; Chou, Chien

    2007-11-01

    Alpha-fetoprotein (AFP) detection by using a localized surface plasmon coupled fluorescence (LSPCF) fiber-optic biosensor is setup and experimentally demonstrated. It is based on gold nanoparticle (GNP) and coupled with localized surface plasmon wave on the surface of GNP. In this experiment, the fluorophores are labeled on anti-AFP which are bound to protein A conjugated GNP. Thus, LSPCF is excited with high efficiency in the near field of localized surface plasmon wave. Therefore, not only the sensitivity of LSPCF biosensor is enhanced but also the specific selectivity of AFP is improved. Experimentally, the ability of real time measurement in the range of AFP concentration from 0.1ng/ml to 100ng/ml was detected. To compare with conventional methods such as enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA), the LSPCF fiber-optic biosensor performs higher or comparable detection sensitivity, respectively.

  5. Highly sensitive rapid fluorescence detection of protein residues on surgical instruments

    Energy Technology Data Exchange (ETDEWEB)

    Kovalev, Valeri I [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Bartona, James S [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Richardson, Patricia R [School of Chemistry, University of Edinburgh, Edinburgh, EH9 3JJ (United Kingdom); Jones, Anita C [School of Chemistry, University of Edinburgh, Edinburgh, EH9 3JJ (United Kingdom)

    2006-07-15

    There is a risk of contamination of surgical instruments by infectious protein residues, in particular, prions which are the agents for Creutzfeldt-Jakob Disease in humans. They are exceptionally resistant to conventional sterilization, therefore it is important to detect their presence as contaminants so that alternative cleaning procedures can be applied. We describe the development of an optimized detection system for fluorescently labelled protein, suitable for in-hospital use. We show that under optimum conditions the technique can detect {approx}10 attomole/cm{sup 2} with a scan speed of {approx}3-10 cm{sup 2}/s of the test instrument's surface. A theoretical analysis and experimental measurements will be discussed.

  6. A recombinant estrogen receptor fragment-based homogeneous fluorescent assay for rapid detection of estrogens.

    Science.gov (United States)

    Wang, Dan; Xie, Jiangbi; Zhu, Xiaocui; Li, Jinqiu; Zhao, Dongqin; Zhao, Meiping

    2014-05-15

    In this work, we demonstrate a novel estrogenic receptor fragment-based homogeneous fluorescent assay which enables rapid and sensitive detection of 17β-estradiol (E2) and other highly potent estrogens. A modified human estrogenic receptor fragment (N-His × 6-hER270-595-C-Strep tag II) has been constructed that contains amino acids 270-595 of wild-type human estrogenic receptor α (hER270-595) and two specific tags (6 × His and Strep tag II) fused to the N and C terminus, respectively. The designed receptor protein fragment could be easily produced by prokaryotic expression with high yield and high purity. The obtained protein exhibits high binding affinity to E2 and the two tags greatly facilitate the application of the recombinant protein. Taking advantage of the unique spectroscopic properties of coumestrol (CS), a fluorescent phytoestrogen, a CS/hER270-595-based fluorescent assay has been developed which can sensitively respond to E2 within 1.0 min with a linear working range from 0.1 to 20 ng/mL and a limit of detection of 0.1 ng/mL. The assay was successfully applied for rapid detection of E2 in the culture medium of rat hippocampal neurons. The method also holds great potential for high-throughput monitoring the variation of estrogen levels in complex biological fluids, which is crucial for investigation of the molecular basis of various estrogen-involved processes. Copyright © 2013 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2018-04-05

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

  8. Improved Diffuse Fluorescence Flow Cytometer Prototype for High Sensitivity Detection of Rare Circulating Cells In Vivo

    Science.gov (United States)

    Pestana, Noah Benjamin

    Accurate quantification of circulating cell populations is important in many areas of pre-clinical and clinical biomedical research, for example, in the study of cancer metastasis or the immune response following tissue and organ transplants. Normally this is done "ex-vivo" by drawing and purifying a small volume of blood and then analyzing it with flow cytometry, hemocytometry or microfludic devices, but the sensitivity of these techniques are poor and the process of handling samples has been shown to affect cell viability and behavior. More recently "in vivo flow cytometry" (IVFC) techniques have been developed where fluorescently-labeled cells flowing in a small blood vessel in the ear or retina are analyzed, but the sensitivity is generally poor due to the small sampling volume. To address this, our group recently developed a method known as "Diffuse Fluorescence Flow Cytometry" (DFFC) that allows detection and counting of rare circulating cells with diffuse photons, offering extremely high single cell counting sensitivity. In this thesis, an improved DFFC prototype was designed and validated. The chief improvements were three-fold, i) improved optical collection efficiency, ii) improved detection electronics, and iii) development of a method to mitigate motion artifacts during in vivo measurements. In combination, these improvements yielded an overall instrument detection sensitivity better than 1 cell/mL in vivo, which is the most sensitive IVFC system reported to date. Second, development and validation of a low-cost microfluidic device reader for analysis of ocular fluids is described. We demonstrate that this device has equivalent or better sensitivity and accuracy compared a fluorescence microscope, but at an order-of-magnitude reduced cost with simplified operation. Future improvements to both instruments are also discussed.

  9. Use of x-ray fluorescence for in-situ detection of metals

    Science.gov (United States)

    Elam, W. T. E.; Whitlock, Robert R.; Gilfrich, John V.

    1995-01-01

    X-ray fluorescence (XRF) is a well-established, non-destructive method of determining elemental concentrations at ppm levels in complex samples. It can operate in atmosphere with no sample preparation, and provides accuracies of 1% or better under optimum conditions. This report addresses two sets of issues concerning the use of x-ray fluorescence as a sensor technology for the cone penetrometer, for shipboard waste disposal, or for other in-situ, real- time environmental applications. The first issue concerns the applicability of XRF to these applications, and includes investigation of detection limits and matrix effects. We have evaluated the detection limits and quantitative accuracy of a sensor mock-up for metals in soils under conditions expected in the field. In addition, several novel ways of improving the lower limits of detection to reach the drinking water regulatory limits have been explored. The second issue is the engineering involved with constructing a spectrometer within the 1.75 inch diameter of the penetrometer pipe, which is the most rigorous physical constraint. Only small improvements over current state-of-the-art are required. Additional advantages of XRF are that no radioactive sources or hazardous materials are used in the sensor design, and no reagents or any possible sources of ignition are involved.

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

    Science.gov (United States)

    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.

  11. Portable detection system of vegetable oils based on laser induced fluorescence

    Science.gov (United States)

    Zhu, Li; Zhang, Yinchao; Chen, Siying; Chen, He; Guo, Pan; Mu, Taotao

    2015-11-01

    Food safety, especially edible oils, has attracted more and more attention recently. Many methods and instruments have emerged to detect the edible oils, which include oils classification and adulteration. It is well known than the adulteration is based on classification. Then, in this paper, a portable detection system, based on laser induced fluorescence, is proposed and designed to classify the various edible oils, including (olive, rapeseed, walnut, peanut, linseed, sunflower, corn oils). 532 nm laser modules are used in this equipment. Then, all the components are assembled into a module (100*100*25mm). A total of 700 sets of fluorescence data (100 sets of each type oil) are collected. In order to classify different edible oils, principle components analysis and support vector machine have been employed in the data analysis. The training set consisted of 560 sets of data (80 sets of each oil) and the test set consisted of 140 sets of data (20 sets of each oil). The recognition rate is up to 99%, which demonstrates the reliability of this potable system. With nonintrusive and no sample preparation characteristic, the potable system can be effectively applied for food detection.

  12. Highly sensitive immunoassay of protein molecules based on single nanoparticle fluorescence detection in a nanowell

    Science.gov (United States)

    Han, Jin-Hee; Kim, Hee-Joo; Lakshmana, Sudheendra; Gee, Shirley J.; Hammock, Bruce D.; Kennedy, Ian M.

    2011-03-01

    A nanoarray based-single molecule detection system was developed for detecting proteins with extremely high sensitivity. The nanoarray was able to effectively trap nanoparticles conjugated with biological sample into nanowells by integrating with an electrophoretic particle entrapment system (EPES). The nanoarray/EPES is superior to other biosensor using immunoassays in terms of saving the amounts of biological solution and enhancing kinetics of antibody binding due to reduced steric hindrance from the neighboring biological molecules. The nanoarray patterned onto a layer of PMMA and LOL on conductive and transparent indium tin oxide (ITO)-glass slide by using e-beam lithography. The suspension of 500 nm-fluorescent (green emission)-carboxylated polystyrene (PS) particles coated with protein-A followed by BDE 47 polyclonal antibody was added to the chip that was connected to the positive voltage. The droplet was covered by another ITO-coated-glass slide and connected to a ground terminal. After trapping the particles into the nanowells, the solution of different concentrations of anti-rabbit- IgG labeled with Alexa 532 was added for an immunoassay. A single molecule detection system could quantify the anti-rabbit IgG down to atto-mole level by counting photons emitted from the fluorescent dye bound to a single nanoparticle in a nanowell.

  13. Investigation of common fluorophores for the detection of nitrated explosives by fluorescence quenching

    International Nuclear Information System (INIS)

    Meaney, Melissa S.; McGuffin, Victoria L.

    2008-01-01

    Previous studies have indicated that nitrated explosives may be detected by fluorescence quenching of pyrene and related compounds. The use of pyrene, however, invokes numerous health and waste disposal hazards. In the present study, ten safer fluorophores are identified for quenching detection of target nitrated compounds. Initially, Stern-Volmer constants are measured for each fluorophore with nitrobenzene and 4-nitrotoluene to determine the sensitivity of the quenching interaction. For quenching constants greater than 50 M -1 , sensitivity and selectivity are investigated further using an extended set of target quenchers. Nitromethane, nitrobenzene, 4-nitrotoluene, and 2,6-dinitrotoluene are chosen to represent nitrated explosives and their degradation products; aniline, benzoic acid, and phenol are chosen to represent potential interfering compounds. Among the fluorophores investigated, purpurin, malachite green, and phenol red demonstrate the greatest sensitivity and selectivity for nitrated compounds. Correlation of the quenching rate constants for these fluorophores to Rehm-Weller theory suggests an electron-transfer quenching mechanism. As a result of the large quenching constants, purpurin, malachite green, and phenol red are the most promising for future detection of nitrated explosives via fluorescence quenching

  14. Pancreatic tumor detection using hypericin-based fluorescence spectroscopy and cytology

    Science.gov (United States)

    Lavu, Harish; Geary, Kevin; Fetterman, Harold R.; Saxton, Romaine E.

    2005-04-01

    Hypericin is a novel, highly fluorescent photosensitizer that exhibits selective tumor cell uptake properties and is particularly resistant to photobleaching. In this study, we have characterized hypericin uptake in human pancreatic tumor cells with relation to incubation time, cell number, and drug concentration. Ex vivo hypericin based fluorescence spectroscopy was performed to detect the presence of MIA PaCa-2 pancreatic tumor cells in the peritoneal cavity of BALB/c nude mice, as well as to quantify gross tumor burden. Hypericin based cytology of peritoneal lavage samples, using both one and two photon laser confocal microscopy, demonstrated more than a two-fold increase in fluorescence emission of pancreatic tumor cells as compared to control samples. In vitro treatment of pancreatic cancer cells with hypericin based photodynamic therapy showed tumor cell cytotoxicity in a drug dose, incident laser power, and time dependent manner. For these experiments, a continuous wavelength solid-state laser source (532 nm) was operated at power levels in the range of 100-400 mW. Potential applications of hypericin in tumor diagnosis, staging, and therapy will be presented.

  15. Adaptive Spot Detection With Optimal Scale Selection in Fluorescence Microscopy Images.

    Science.gov (United States)

    Basset, Antoine; Boulanger, Jérôme; Salamero, Jean; Bouthemy, Patrick; Kervrann, Charles

    2015-11-01

    Accurately detecting subcellular particles in fluorescence microscopy is of primary interest for further quantitative analysis such as counting, tracking, or classification. Our primary goal is to segment vesicles likely to share nearly the same size in fluorescence microscopy images. Our method termed adaptive thresholding of Laplacian of Gaussian (LoG) images with autoselected scale (ATLAS) automatically selects the optimal scale corresponding to the most frequent spot size in the image. Four criteria are proposed and compared to determine the optimal scale in a scale-space framework. Then, the segmentation stage amounts to thresholding the LoG of the intensity image. In contrast to other methods, the threshold is locally adapted given a probability of false alarm (PFA) specified by the user for the whole set of images to be processed. The local threshold is automatically derived from the PFA value and local image statistics estimated in a window whose size is not a critical parameter. We also propose a new data set for benchmarking, consisting of six collections of one hundred images each, which exploits backgrounds extracted from real microscopy images. We have carried out an extensive comparative evaluation on several data sets with ground-truth, which demonstrates that ATLAS outperforms existing methods. ATLAS does not need any fine parameter tuning and requires very low computation time. Convincing results are also reported on real total internal reflection fluorescence microscopy images.

  16. Detection of vegetation LUE based on chlorophyll fluorescence separation algorithm from Fraunhofer line

    Science.gov (United States)

    Liu, Liangyun; Zhang, Bing

    2009-09-01

    Photosynthetic efficiency is very important, and not yet generally assessable by remote sensing. Much research has proved the possibility of the separation of solar-induced chlorophyll fluorescence (ChlF) from the reflected hyperspectral data. As the 'probe' of plant photosynthesis, it is possible to detect photosynthetic light use efficiency (LUE) by the separated solar-induced ChlF. A diurnal experiment was carried out on winter wheat on Apr. 18, 2008, and the canopy radiance spectra and leaf LUE data were measured synchronously. The solar-induced chlorophyll fluorescence signals at 760nm and 688nm were separated from the reflected radiance spectral based on Fraunhofer lines in two oxygen absorption bands. The result showed that LUE was negatively correlated to the separated chlorophyll signals. The statistical models for LUE based on the solar-induced chlorophyll fluorescence values at 688 nm and 760 nm bands had correlation coefficients (R2) of 0.64 and 0.78, respectively. In addition, photochemical reflectance index (PRI) was also linked to LUE, and a statistical model for LUE based on PRI has a correlation coefficient (R2) of 0.66. The presented method provides a novel solution for monitoring LUE from remote sensing data.

  17. Liquid chromatographic determination with fluorescence detection of B6 vitamers and riboflavin in milk and pharmaceuticals

    International Nuclear Information System (INIS)

    Gatti, R.; Gioia, M.G.

    2005-01-01

    A simple, reliable and selective high performance liquid chromatographic method with fluorescence detection at different programmed wavelengths has been developed for the simultaneous analysis of B 6 vitamers (pyridoxal 5'-phosphate, 4-pyridoxic acid, pyridoxal, pyridoxine and pyridoxamine) and Vitamin B 2 in commercial vitaminized milk and in woman milk. The chromatographic separations were performed on a reversed phase octyl column by using a mobile phase consisting of sodium pentanesulfonate in 1% acetic acid-methanol-tetrahydrofuran under gradient elution conditions. The fluorescence intensity of pyridoxal 5'-phosphate was enhanced by post-column photochemical conversion, giving significantly different fluorescence spectra by a on-line photoreactor switched OFF and ON under irradiation at 254 nm. In addition, a simple and rapid method in isocratic conditions without the need of photochemical conversion was proposed for the analysis of Vitamin B 6 and Vitamin B 2 in pharmaceuticals. Linearity, precision, recovery, selectivity and sensitivity were found satisfactory for each analysed compound. Quantitation limits ranged from 26 to 240 fmol

  18. Multispectral fluorescence imaging of human ovarian and Fallopian tube tissue for early stage cancer detection

    Science.gov (United States)

    Tate, Tyler; Baggett, Brenda; Rice, Photini; Watson, Jennifer; Orsinger, Gabe; Nymeyer, Ariel C.; Welge, Weston A.; Keenan, Molly; Saboda, Kathylynn; Roe, Denise J.; Hatch, Kenneth; Chambers, Setsuko; Black, John; Utzinger, Urs; Barton, Jennifer

    2015-03-01

    With early detection, five year survival rates for ovarian cancer are over 90%, yet no effective early screening method exists. Emerging consensus suggests that perhaps over 50% of the most lethal form of the disease, high grade serous ovarian cancer, originates in the Fallopian tube. Cancer changes molecular concentrations of various endogenous fluorophores. Using specific excitation wavelengths and emissions bands on a Multispectral Fluorescence Imaging (MFI) system, spatial and spectral data over a wide field of view can be collected from endogenous fluorophores. Wavelength specific reflectance images provide additional information to normalize for tissue geometry and blood absorption. Ratiometric combination of the images may create high contrast between neighboring normal and abnormal tissue. Twenty-six women undergoing oophorectomy or debulking surgery consented the use of surgical discard tissue samples for MFI imaging. Forty-nine pieces of ovarian tissue and thirty-two pieces of Fallopian tube tissue were collected and imaged with excitation wavelengths between 280 nm and 550 nm. After imaging, each tissue sample was fixed, sectioned and HE stained for pathological evaluation. Comparison of mean intensity values between normal, benign, and cancerous tissue demonstrate a general trend of increased fluorescence of benign tissue and decreased fluorescence of cancerous tissue when compared to normal tissue. The predictive capabilities of the mean intensity measurements are tested using multinomial logistic regression and quadratic discriminant analysis. Adaption of the system for in vivo Fallopian tube and ovary endoscopic imaging is possible and is briefly described.

  19. Detection of wood cell wall porosity using small carbohydrate molecules and confocal fluorescence microscopy.

    Science.gov (United States)

    Donaldson, L A; Kroese, H W; Hill, S J; Franich, R A

    2015-09-01

    A novel approach to nanoscale detection of cell wall porosity using confocal fluorescence microscopy is described. Infiltration of cell walls with a range of nitrophenyl-substituted carbohydrates of different molecular weights was assessed by measuring changes in the intensity of lignin fluorescence, in response to the quenching effect of the 4-nitrophenyl group. The following carbohydrates were used in order of increasing molecular weight; 4-nitrophenyl β-D-glucopyrano-side (monosaccharide), 4-nitrophenyl β-D-lactopyranoside (disaccharide), 2-chloro-4-nitrophenyl β-D-maltotrioside (trisaccharide), and 4-nitrophenyl α-D-maltopentaoside (pentasaccharide). This technique was used to compare cell wall porosity in wood which had been dewatered to 40% moisture content using supercritical CO2, where cell walls remain fully hydrated, with kiln dried wood equilibrated to 12% moisture content. Infiltration of cell walls as measured by fluorescence quenching, was found to decrease with increasing molecular weight, with the pentasaccharide being significantly excluded compared to the monosaccharide. Porosity experiments were performed on blocks and sections to assess differences in cell wall accessibility. Dewatered and kiln dried wood infiltrated as blocks showed similar results, but greater infiltration was achieved by using sections, indicating that not all pores were easily accessible by infiltration from the lumen surface. In wood blocks infiltrated with 4-nitrophenyl α-D-maltopentaoside, quenching of the secondary wall was quite variable, especially in kiln dried wood, indicating limited connectivity of pores accessible from the lumen surface. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  20. Smartphone Cortex Controlled Real-Time Image Processing and Reprocessing for Concentration Independent LED Induced Fluorescence Detection in Capillary Electrophoresis.

    Science.gov (United States)

    Szarka, Mate; Guttman, Andras

    2017-10-17

    We present the application of a smartphone anatomy based technology in the field of liquid phase bioseparations, particularly in capillary electrophoresis. A simple capillary electrophoresis system was built with LED induced fluorescence detection and a credit card sized minicomputer to prove the concept of real time fluorescent imaging (zone adjustable time-lapse fluorescence image processor) and separation controller. The system was evaluated by analyzing under- and overloaded aminopyrenetrisulfonate (APTS)-labeled oligosaccharide samples. The open source software based image processing tool allowed undistorted signal modulation (reprocessing) if the signal was inappropriate for the actual detection system settings (too low or too high). The novel smart detection tool for fluorescently labeled biomolecules greatly expands dynamic range and enables retrospective correction for injections with unsuitable signal levels without the necessity to repeat the analysis.

  1. In-vacuum scattered light reduction with black cupric oxide surfaces for sensitive fluorescence detection.

    Science.gov (United States)

    Norrgard, E B; Sitaraman, N; Barry, J F; McCarron, D J; Steinecker, M H; DeMille, D

    2016-05-01

    We demonstrate a simple and easy method for producing low-reflectivity surfaces that are ultra-high vacuum compatible, may be baked to high temperatures, and are easily applied even on complex surface geometries. Black cupric oxide (CuO) surfaces are chemically grown in minutes on any copper surface, allowing for low-cost, rapid prototyping, and production. The reflective properties are measured to be comparable to commercially available products for creating optically black surfaces. We describe a vacuum apparatus which uses multiple blackened copper surfaces for sensitive, low-background detection of molecules using laser-induced fluorescence.

  2. Flame Front Detection Using Formaldehyde Laser Induced Fluorescence In Turbulent Lean Premixed Flames

    Energy Technology Data Exchange (ETDEWEB)

    Schenker, S.; Tylli, N.; Bombach, R.

    2005-03-01

    The present work aims at suggesting the excitation-detection scheme best suited for laser-induced fluorescence measurements of formaldehyde in turbulent lean premixed flames. In the literature, three different excitation schemes within the A{sup 1} X{sup 1} electronic transition have been suggested, with excitation into the 2{sup 1}{sub 0} 4{sup 1}{sub 0} , 4{sup 1}{sub 0} , and 4{sup 0}{sub 1} vibratoric bands, respectively. These excitation schemes were tested systematically and both advantages and disadvantages for each scheme are discussed. (author)

  3. InP/ZnS Nanocrystals as Fluorescent Probes for the Detection of ATP

    OpenAIRE

    Massadeh, Salam; Nann, Thomas

    2014-01-01

    This article reports on a study on fluorescence adenosine triphosphate (ATP) detection by InP/ZnS quantum dots (QDs). We present a spectroscopic analysis displaying the effect of enzymatic reactions of glucose oxidase (GOX) and hexokinase (HEX) on the InP/ZnS quantum dots at physiological pH. The InP/ZnS quantum dots act as glucose sensors in the presence of GOX, Glu and ATP, and their luminescence quenches during the release of hydrogen peroxide from the reaction. However, in the presence of...

  4. Surface extended x-ray absorption fine structure of low-Z absorbates using fluorescence detection

    International Nuclear Information System (INIS)

    Stoehr, J.; Kollin, E.B.; Fischer, D.A.; Hastings, J.B.; Zaera, F.; Sette, F.

    1985-05-01

    Comparison of x-ray fluorescence yield (FY) and electron yield surface extended x-ray absorption fine structure spectra above the S K-edge for c(2 x 2) S on Ni(100) reveals an order of magnitude higher sensitivity of the FY technique. Using FY detection, thiophene (C 4 H 4 S) chemisorption on Ni(100) is studied with S coverages down to 0.08 monolayer. The molecule dissociates at temperatures as low as 100K by interaction with fourfold hollow Ni sites. Blocking of these sites by oxygen leaves the molecule intact

  5. Reaction rate constant of HO2+O3 measured by detecting HO2 from photofragment fluorescence

    Science.gov (United States)

    Manzanares, E. R.; Suto, Masako; Lee, Long C.; Coffey, Dewitt, Jr.

    1986-01-01

    A room-temperature discharge-flow system investigation of the rate constant for the reaction 'HO2 + O3 yields OH + 2O2' has detected HO2 through the OH(A-X) fluorescence produced by photodissociative excitation of HO2 at 147 nm. A reaction rate constant of 1.9 + or - 0.3 x 10 to the -15th cu cm/molecule per sec is obtained from first-order decay of HO2 in excess O3; this agrees well with published data.

  6. A novel and sensitive fluorescence sensor for glutathione detection by controlling the surface passivation degree of carbon quantum dots.

    Science.gov (United States)

    Pan, Jiahong; Zheng, Zengyao; Yang, Jianying; Wu, Yaoyu; Lu, Fushen; Chen, Yaowen; Gao, Wenhua

    2017-05-01

    A novel fluorescence sensor based on controlling the surface passivation degree of carbon quantum dots (CQDs) was developed for glutathione (GSH) detection. First, we found that the fluorescence intensity of the CQDs which was obtained by directly pyrolyzing citric acid would increased largely after the surface passivation treatment by 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC). In the light of this phenomenon, we designed a simple, rapid and selective fluorescence sensor based on the surface passivated CQDs. A certain and excess amount of EDC were mixed with GSH, part of EDC would form a stable complex with GSH owing to the exposed sulfhydryl group of GSH. As the synthesized CQDs were added into the above mixture solution, the fluorescence intensity of the (EDC/GSH)/CQDs mixture solution could be directly related to the amount of GSH. Compared to other fluorescence analytical methods, the fluorescence sensor we design is neither the traditional fluorescent "turn on" probes nor "turn off" probes. It is a new fluorescence analytical method that target object indirectly control the surface passivation degree of CQDs so that it can realize the detection of the target object. Moreover, the proposed method manifested great advantages including short analysis time, low cost and ease of operation. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Detection of NT-pro BNP using fluorescent protein modified by streptavidin as a label in immunochromatographic assay

    Directory of Open Access Journals (Sweden)

    Haixia Li

    2016-12-01

    Full Text Available A novel fluorescent immunochromatographic assay for the detection of NT-proBNP in human serum has been developed. Based on a sandwich-type immunoassay format, analytes in samples were captured by one monoclonal antibody labeled with fluorescent protein and “sandwiched” by another monoclonal antibody immobilized on the nitrocellulose membrane, the fluorescence and concentration of analytes were measured and then calculated by fluoroanalyzer. The fluorescent protein is a fusion protein and was prepared through the application of Streptavidin gene SA, β subunit cpcB of Phycocyanin, lyase alr0617, and phycoerythrobilin synthetase gene ho1, pebA, pebB for covalent binding. It is characterized with higher stability, good solubility in water and it is not easy to quench fluorescence. Take the advantages of fluorescent protein, the immunochromatographic assay exhibited a wide linear range for NT-proBNP from 200 pg ml−1 to 26,000 pg ml−1, with a detection limit of 47 pg ml−1 under optimal conditions. Compared with chemiluminescence immunoassay (CLIA, 131 human serum samples were analyzed and the correlation coefficient of the developed immunoassay was 0.978. These results demonstrated that fluorescent immunochromatographic assay is a more rapid, sensitive, specific method and could be developed into a platform for more biomarkers determination in clinical practice. Keywords: NT-pro BNP, Fluorescent protein, Immunochromatographic assay

  8. Folic acid functionalized silver nanoparticles with sensitivity and selectivity colorimetric and fluorescent detection for Hg2+ and efficient catalysis.

    Science.gov (United States)

    Su, Dongyue; Yang, Xin; Xia, Qingdong; Zhang, Qi; Chai, Fang; Wang, Chungang; Qu, Fengyu

    2014-09-05

    In this research, folic acid functionalized silver nanoparticles (FA-AgNPs) were selected as a colorimetric and a 'turn on' fluorescent sensor for detecting Hg(2+). After being added into Hg(2+), AgNPs can emit stable fluorescence at 440 nm when the excitation wavelength is selected at 275 nm. The absorbance and fluorescence of the FA-AgNPs could reflect the concentration of the Hg(2+) ions. Thus, we developed a simple, sensitive analytical method to detect Hg(2+) based on the colorimetric and fluorescence enhancement of FA-AgNPs. The sensor exhibits two linear response ranges between absorbance and fluorescence intensity with Hg(2+) concentration, respectively. Meanwhile, a detection limit of 1 nM is estimated based on the linear relationship between responses with a concentration of Hg(2+). The high specificity of Hg(2+) with FA-AgNPs interactions provided the excellent selectivity towards detecting Hg(2+) over other metal ions (Pb(2+), Mg(2+), Zn(2+), Ni(2+), Cu(2+), Co(2+), Ca(2+), Mn(2+), Fe(2+), Cd(2+), Ba(2+), Cr(6+) and Cr(3+)). This will provide a simple, effective and multifunctional colorimetric and fluorescent sensor for on-site and real-time Hg(2+) ion detection. The proposed method can be applied to the analysis of trace Hg(2+) in lake water. Additionally, the FA-AgNPs can be used as efficient catalyst for the reduction of 4-nitrophenol and potassium hexacyanoferrate (III).

  9. Comparative study of protoporphyrin IX fluorescence image enhancement methods to improve an optical imaging system for oral cancer detection

    Science.gov (United States)

    Jiang, Ching-Fen; Wang, Chih-Yu; Chiang, Chun-Ping

    2011-07-01

    Optoelectronics techniques to induce protoporphyrin IX fluorescence with topically applied 5-aminolevulinic acid on the oral mucosa have been developed to noninvasively detect oral cancer. Fluorescence imaging enables wide-area screening for oral premalignancy, but the lack of an adequate fluorescence enhancement method restricts the clinical imaging application of these techniques. This study aimed to develop a reliable fluorescence enhancement method to improve PpIX fluorescence imaging systems for oral cancer detection. Three contrast features, red-green-blue reflectance difference, R/B ratio, and R/G ratio, were developed first based on the optical properties of the fluorescence images. A comparative study was then carried out with one negative control and four biopsy confirmed clinical cases to validate the optimal image processing method for the detection of the distribution of malignancy. The results showed the superiority of the R/G ratio in terms of yielding a better contrast between normal and neoplastic tissue, and this method was less prone to errors in detection. Quantitative comparison with the clinical diagnoses in the four neoplastic cases showed that the regions of premalignancy obtained using the proposed method accorded with the expert's determination, suggesting the potential clinical application of this method for the detection of oral cancer.

  10. Fluorometric detection of nitroaromatics by fluorescent lead complexes: A spectroscopic assessment of detection mechanism

    Science.gov (United States)

    Chattopadhyay, Tanmay; Chatterjee, Sourav; Majumder, Ishani; Ghosh, Soumen; Yoon, Sangee; Sim, Eunji

    2018-04-01

    Three Schiff base ligands such as 2-[(2-Hydroxy-3-methoxy-benzylidene)-amino]-2-hydroxymethyl-propane-1,3-diol (HL1), 2-[(2-Hydroxy-benzylidene)-amino]-2-hydroxymethyl-propane-1,3-diol (HL2), 2-[(3,5-Dichloro-2-hydroxy-benzylidene)-amino]-2-hydroxymethyl-propane-1,3-diol (HL3) have been synthesized by condensation of aldehydes (such as 3,5-Dichloro-2-hydroxy benzaldehyde, 2-Hydroxy-benzaldehyde, and 2-Hydroxy-3-methoxy-benzaldehyde) with Tris-(hydroxymethyl)amino methane and characterized by IR, UV-vis and 1H NMR spectroscopy. Then all these three ligands have been used to prepare Pb(II) complexes by reaction with lead(II) acetate tri-hydrate in methanol. In view of analytical and spectral (IR, UV-vis and Mass) studies, it has been concluded that, except HL2, other two ligands form 1:1 metal complexes (1 and 3) with lead. Between two complexes, complex 3 is highly fluorescent and this property has been used to identify the pollutant nitroaromatics. Finally, the quenching mechanism has been established by means of spectroscopic investigation.

  11. Micro-Droplet Detection Method for Measuring the Concentration of Alkaline Phosphatase-Labeled Nanoparticles in Fluorescence Microscopy

    Directory of Open Access Journals (Sweden)

    Rufeng Li

    2017-11-01

    Full Text Available This paper developed and evaluated a quantitative image analysis method to measure the concentration of the nanoparticles on which alkaline phosphatase (AP was immobilized. These AP-labeled nanoparticles are widely used as signal markers for tagging biomolecules at nanometer and sub-nanometer scales. The AP-labeled nanoparticle concentration measurement can then be directly used to quantitatively analyze the biomolecular concentration. Micro-droplets are mono-dispersed micro-reactors that can be used to encapsulate and detect AP-labeled nanoparticles. Micro-droplets include both empty micro-droplets and fluorescent micro-droplets, while fluorescent micro-droplets are generated from the fluorescence reaction between the APs adhering to a single nanoparticle and corresponding fluorogenic substrates within droplets. By detecting micro-droplets and calculating the proportion of fluorescent micro-droplets to the overall micro-droplets, we can calculate the AP-labeled nanoparticle concentration. The proposed micro-droplet detection method includes the following steps: (1 Gaussian filtering to remove the noise of overall fluorescent targets, (2 a contrast-limited, adaptive histogram equalization processing to enhance the contrast of weakly luminescent micro-droplets, (3 an red maximizing inter-class variance thresholding method (OTSU to segment the enhanced image for getting the binary map of the overall micro-droplets, (4 a circular Hough transform (CHT method to detect overall micro-droplets and (5 an intensity-mean-based thresholding segmentation method to extract the fluorescent micro-droplets. The experimental results of fluorescent micro-droplet images show that the average accuracy of our micro-droplet detection method is 0.9586; the average true positive rate is 0.9502; and the average false positive rate is 0.0073. The detection method can be successfully applied to measure AP-labeled nanoparticle concentration in fluorescence microscopy.

  12. Micro-Droplet Detection Method for Measuring the Concentration of Alkaline Phosphatase-Labeled Nanoparticles in Fluorescence Microscopy.

    Science.gov (United States)

    Li, Rufeng; Wang, Yibei; Xu, Hong; Fei, Baowei; Qin, Binjie

    2017-11-21

    This paper developed and evaluated a quantitative image analysis method to measure the concentration of the nanoparticles on which alkaline phosphatase (AP) was immobilized. These AP-labeled nanoparticles are widely used as signal markers for tagging biomolecules at nanometer and sub-nanometer scales. The AP-labeled nanoparticle concentration measurement can then be directly used to quantitatively analyze the biomolecular concentration. Micro-droplets are mono-dispersed micro-reactors that can be used to encapsulate and detect AP-labeled nanoparticles. Micro-droplets include both empty micro-droplets and fluorescent micro-droplets, while fluorescent micro-droplets are generated from the fluorescence reaction between the APs adhering to a single nanoparticle and corresponding fluorogenic substrates within droplets. By detecting micro-droplets and calculating the proportion of fluorescent micro-droplets to the overall micro-droplets, we can calculate the AP-labeled nanoparticle concentration. The proposed micro-droplet detection method includes the following steps: (1) Gaussian filtering to remove the noise of overall fluorescent targets, (2) a contrast-limited, adaptive histogram equalization processing to enhance the contrast of weakly luminescent micro-droplets, (3) an red maximizing inter-class variance thresholding method (OTSU) to segment the enhanced image for getting the binary map of the overall micro-droplets, (4) a circular Hough transform (CHT) method to detect overall micro-droplets and (5) an intensity-mean-based thresholding segmentation method to extract the fluorescent micro-droplets. The experimental results of fluorescent micro-droplet images show that the average accuracy of our micro-droplet detection method is 0.9586; the average true positive rate is 0.9502; and the average false positive rate is 0.0073. The detection method can be successfully applied to measure AP-labeled nanoparticle concentration in fluorescence microscopy.

  13. A fluorescence high throughput screening method for the detection of reactive electrophiles as potential skin sensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Avonto, Cristina; Chittiboyina, Amar G. [National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, The University of Mississippi, University, MS 38677 (United States); Rua, Diego [The Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD 20740 (United States); Khan, Ikhlas A., E-mail: ikhan@olemiss.edu [National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, The University of Mississippi, University, MS 38677 (United States); Division of Pharmacognosy, Department of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS 38677 (United States)

    2015-12-01

    Skin sensitization is an important toxicological end-point in the risk assessment of chemical allergens. Because of the complexity of the biological mechanisms associated with skin sensitization, integrated approaches combining different chemical, biological and in silico methods are recommended to replace conventional animal tests. Chemical methods are intended to characterize the potential of a sensitizer to induce earlier molecular initiating events. The presence of an electrophilic mechanistic domain is considered one of the essential chemical features to covalently bind to the biological target and induce further haptenation processes. Current in chemico assays rely on the quantification of unreacted model nucleophiles after incubation with the candidate sensitizer. In the current study, a new fluorescence-based method, ‘HTS-DCYA assay’, is proposed. The assay aims at the identification of reactive electrophiles based on their chemical reactivity toward a model fluorescent thiol. The reaction workflow enabled the development of a High Throughput Screening (HTS) method to directly quantify the reaction adducts. The reaction conditions have been optimized to minimize solubility issues, oxidative side reactions and increase the throughput of the assay while minimizing the reaction time, which are common issues with existing methods. Thirty-six chemicals previously classified with LLNA, DPRA or KeratinoSens™ were tested as a proof of concept. Preliminary results gave an estimated 82% accuracy, 78% sensitivity, 90% specificity, comparable to other in chemico methods such as Cys-DPRA. In addition to validated chemicals, six natural products were analyzed and a prediction of their sensitization potential is presented for the first time. - Highlights: • A novel fluorescence-based method to detect electrophilic sensitizers is proposed. • A model fluorescent thiol was used to directly quantify the reaction products. • A discussion of the reaction workflow

  14. In-vivo fluorescence detection of breast cancer growth factor receptors by fiber-optic probe

    Science.gov (United States)

    Bustamante, Gilbert; Wang, Bingzhi; DeLuna, Frank; Sun, LuZhe; Ye, Jing Yong

    2018-02-01

    Breast cancer treatment options often include medications that target the overexpression of growth factor receptors, such as the proto-oncogene human epidermal growth factor receptor 2 (HER2/neu) and epidermal growth factor receptor (EGFR) to suppress the abnormal growth of cancerous cells and induce cancer regression. Although effective, certain treatments are toxic to vital organs, and demand assurance that the pursued receptor is present at the tumor before administration of the drug. This requires diagnostic tools to provide tumor molecular signatures, as well as locational information. In this study, we utilized a fiber-optic probe to characterize in vivo HER2 and EGFR overexpressed tumors through the fluorescence of targeted dyes. HER2 and EGFR antibodies were conjugated with ICG-Sulfo-OSu and Alexa Fluor 680, respectively, to tag BT474 (HER2+) and MDA-MB-468 (EGFR+) tumors. The fiber was inserted into the samples via a 30-gauge needle. Different wavelengths of a supercontinuum laser were selected to couple into the fiber and excite the corresponding fluorophores in the samples. The fluorescence from the dyes was collected through the same fiber and quantified by a time-correlated single photon counter. Fluorescence at different antibody-dye concentrations was measured for calibration. Mice with subcutaneous HER2+ and/or EGFR+ tumors received intravenous injections of the conjugates and were later probed at the tumor sites. The measured fluorescence was used to distinguish between tumor types and to calculate the concentration of the antibody-dye conjugates, which were detectable at levels as low as 40 nM. The fiber-optic probe presents a minimally invasive instrument to characterize the molecular signatures of breast cancer in vivo.

  15. A fluorescence high throughput screening method for the detection of reactive electrophiles as potential skin sensitizers

    International Nuclear Information System (INIS)

    Avonto, Cristina; Chittiboyina, Amar G.; Rua, Diego; Khan, Ikhlas A.

    2015-01-01

    Skin sensitization is an important toxicological end-point in the risk assessment of chemical allergens. Because of the complexity of the biological mechanisms associated with skin sensitization, integrated approaches combining different chemical, biological and in silico methods are recommended to replace conventional animal tests. Chemical methods are intended to characterize the potential of a sensitizer to induce earlier molecular initiating events. The presence of an electrophilic mechanistic domain is considered one of the essential chemical features to covalently bind to the biological target and induce further haptenation processes. Current in chemico assays rely on the quantification of unreacted model nucleophiles after incubation with the candidate sensitizer. In the current study, a new fluorescence-based method, ‘HTS-DCYA assay’, is proposed. The assay aims at the identification of reactive electrophiles based on their chemical reactivity toward a model fluorescent thiol. The reaction workflow enabled the development of a High Throughput Screening (HTS) method to directly quantify the reaction adducts. The reaction conditions have been optimized to minimize solubility issues, oxidative side reactions and increase the throughput of the assay while minimizing the reaction time, which are common issues with existing methods. Thirty-six chemicals previously classified with LLNA, DPRA or KeratinoSens™ were tested as a proof of concept. Preliminary results gave an estimated 82% accuracy, 78% sensitivity, 90% specificity, comparable to other in chemico methods such as Cys-DPRA. In addition to validated chemicals, six natural products were analyzed and a prediction of their sensitization potential is presented for the first time. - Highlights: • A novel fluorescence-based method to detect electrophilic sensitizers is proposed. • A model fluorescent thiol was used to directly quantify the reaction products. • A discussion of the reaction workflow

  16. Comparison of supervised machine learning algorithms for waterborne pathogen detection using mobile phone fluorescence microscopy

    Science.gov (United States)

    Ceylan Koydemir, Hatice; Feng, Steve; Liang, Kyle; Nadkarni, Rohan; Benien, Parul; Ozcan, Aydogan

    2017-06-01

    Giardia lamblia is a waterborne parasite that affects millions of people every year worldwide, causing a diarrheal illness known as giardiasis. Timely detection of the presence of the cysts of this parasite in drinking water is important to prevent the spread of the disease, especially in resource-limited settings. Here we provide extended experimental testing and evaluation of the performance and repeatability of a field-portable and cost-effective microscopy platform for automated detection and counting of Giardia cysts in water samples, including tap water, non-potable water, and pond water. This compact platform is based on our previous work, and is composed of a smartphone-based fluorescence microscope, a disposable sample processing cassette, and a custom-developed smartphone application. Our mobile phone microscope has a large field of view of 0.8 cm2 and weighs only 180 g, excluding the phone. A custom-developed smartphone application provides a user-friendly graphical interface, guiding the users to capture a fluorescence image of the sample filter membrane and analyze it automatically at our servers using an image processing algorithm and training data, consisting of >30,000 images of cysts and >100,000 images of other fluorescent particles that are captured, including, e.g. dust. The total time that it takes from sample preparation to automated cyst counting is less than an hour for each 10 ml of water sample that is tested. We compared the sensitivity and the specificity of our platform using multiple supervised classification models, including support vector machines and nearest neighbors, and demonstrated that a bootstrap aggregating (i.e. bagging) approach using raw image file format provides the best performance for automated detection of Giardia cysts. We evaluated the performance of this machine learning enabled pathogen detection device with water samples taken from different sources (e.g. tap water, non-potable water, pond water) and achieved a

  17. Comparison of supervised machine learning algorithms for waterborne pathogen detection using mobile phone fluorescence microscopy

    KAUST Repository

    Ceylan Koydemir, Hatice

    2017-06-14

    Giardia lamblia is a waterborne parasite that affects millions of people every year worldwide, causing a diarrheal illness known as giardiasis. Timely detection of the presence of the cysts of this parasite in drinking water is important to prevent the spread of the disease, especially in resource-limited settings. Here we provide extended experimental testing and evaluation of the performance and repeatability of a field-portable and cost-effective microscopy platform for automated detection and counting of Giardia cysts in water samples, including tap water, non-potable water, and pond water. This compact platform is based on our previous work, and is composed of a smartphone-based fluorescence microscope, a disposable sample processing cassette, and a custom-developed smartphone application. Our mobile phone microscope has a large field of view of ~0.8 cm2 and weighs only ~180 g, excluding the phone. A custom-developed smartphone application provides a user-friendly graphical interface, guiding the users to capture a fluorescence image of the sample filter membrane and analyze it automatically at our servers using an image processing algorithm and training data, consisting of >30,000 images of cysts and >100,000 images of other fluorescent particles that are captured, including, e.g. dust. The total time that it takes from sample preparation to automated cyst counting is less than an hour for each 10 ml of water sample that is tested. We compared the sensitivity and the specificity of our platform using multiple supervised classification models, including support vector machines and nearest neighbors, and demonstrated that a bootstrap aggregating (i.e. bagging) approach using raw image file format provides the best performance for automated detection of Giardia cysts. We evaluated the performance of this machine learning enabled pathogen detection device with water samples taken from different sources (e.g. tap water, non-potable water, pond water) and achieved

  18. Comparison of supervised machine learning algorithms for waterborne pathogen detection using mobile phone fluorescence microscopy

    Directory of Open Access Journals (Sweden)

    Ceylan Koydemir Hatice

    2017-06-01

    Full Text Available Giardia lamblia is a waterborne parasite that affects millions of people every year worldwide, causing a diarrheal illness known as giardiasis. Timely detection of the presence of the cysts of this parasite in drinking water is important to prevent the spread of the disease, especially in resource-limited settings. Here we provide extended experimental testing and evaluation of the performance and repeatability of a field-portable and cost-effective microscopy platform for automated detection and counting of Giardia cysts in water samples, including tap water, non-potable water, and pond water. This compact platform is based on our previous work, and is composed of a smartphone-based fluorescence microscope, a disposable sample processing cassette, and a custom-developed smartphone application. Our mobile phone microscope has a large field of view of ~0.8 cm2 and weighs only ~180 g, excluding the phone. A custom-developed smartphone application provides a user-friendly graphical interface, guiding the users to capture a fluorescence image of the sample filter membrane and analyze it automatically at our servers using an image processing algorithm and training data, consisting of >30,000 images of cysts and >100,000 images of other fluorescent particles that are captured, including, e.g. dust. The total time that it takes from sample preparation to automated cyst counting is less than an hour for each 10 ml of water sample that is tested. We compared the sensitivity and the specificity of our platform using multiple supervised classification models, including support vector machines and nearest neighbors, and demonstrated that a bootstrap aggregating (i.e. bagging approach using raw image file format provides the best performance for automated detection of Giardia cysts. We evaluated the performance of this machine learning enabled pathogen detection device with water samples taken from different sources (e.g. tap water, non-potable water, pond

  19. Comparison of supervised machine learning algorithms for waterborne pathogen detection using mobile phone fluorescence microscopy

    KAUST Repository

    Ceylan Koydemir, Hatice; Feng, Steve; Liang, Kyle; Nadkarni, Rohan; Benien, Parul; Ozcan, Aydogan

    2017-01-01

    Giardia lamblia is a waterborne parasite that affects millions of people every year worldwide, causing a diarrheal illness known as giardiasis. Timely detection of the presence of the cysts of this parasite in drinking water is important to prevent the spread of the disease, especially in resource-limited settings. Here we provide extended experimental testing and evaluation of the performance and repeatability of a field-portable and cost-effective microscopy platform for automated detection and counting of Giardia cysts in water samples, including tap water, non-potable water, and pond water. This compact platform is based on our previous work, and is composed of a smartphone-based fluorescence microscope, a disposable sample processing cassette, and a custom-developed smartphone application. Our mobile phone microscope has a large field of view of ~0.8 cm2 and weighs only ~180 g, excluding the phone. A custom-developed smartphone application provides a user-friendly graphical interface, guiding the users to capture a fluorescence image of the sample filter membrane and analyze it automatically at our servers using an image processing algorithm and training data, consisting of >30,000 images of cysts and >100,000 images of other fluorescent particles that are captured, including, e.g. dust. The total time that it takes from sample preparation to automated cyst counting is less than an hour for each 10 ml of water sample that is tested. We compared the sensitivity and the specificity of our platform using multiple supervised classification models, including support vector machines and nearest neighbors, and demonstrated that a bootstrap aggregating (i.e. bagging) approach using raw image file format provides the best performance for automated detection of Giardia cysts. We evaluated the performance of this machine learning enabled pathogen detection device with water samples taken from different sources (e.g. tap water, non-potable water, pond water) and achieved

  20. A novel fluorescence biosensor for sensitivity detection of tyrosinase and acid phosphatase based on nitrogen-doped graphene quantum dots.

    Science.gov (United States)

    Qu, Zhengyi; Na, Weidan; Liu, Xiaotong; Liu, Hua; Su, Xingguang

    2018-01-02

    In this paper, we developed a sensitive fluorescence biosensor for tyrosinase (TYR) and acid phosphatase (ACP) activity detection based on nitrogen-doped graphene quantum dots (N-GQDs). Tyrosine could be catalyzed by TYR to generate dopaquinone, which could efficiently quench the fluorescence of N-GQDs, and the degree of fluorescence quenching of N-GQDs was proportional to the concentration of TYR. In the presence of ACP, l-Ascorbic acid-2-phosphate (AAP) was hydrolyzed to generate ascorbic acid (AA), and dopaquinone was reduced to l-dopa, resulting in the fluorescence recovery of the quenched fluorescence by dopaquinone. Thus, a novel fluorescence biosensor for the detection of TYR and ACP activity based on N-GQDs was constructed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of TYR and ACP in the range of 0.43-3.85 U mL -1 and 0.04-0.7 mU mL -1 with a detection limit of 0.15 U mL -1 and 0.014 mU mL -1 , respectively. The feasibility of the proposed biosensor in real samples assay was also studied and satisfactory results were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

    Science.gov (United States)

    Baran, Timothy M; Foster, Thomas H

    2011-08-01

    We present a new Monte Carlo model of cylindrical diffusing fibers that is implemented with a graphics processing unit. Unlike previously published models that approximate the diffuser as a linear array of point sources, this model is based on the construction of these fibers. This allows for accurate determination of fluence distributions and modeling of fluorescence generation and collection. We demonstrate that our model generates fluence profiles similar to a linear array of point sources, but reveals axially heterogeneous fluorescence detection. With axially homogeneous excitation fluence, approximately 90% of detected fluorescence is collected by the proximal third of the diffuser for μ(s)'∕μ(a) = 8 in the tissue and 70 to 88% is collected in this region for μ(s)'∕μ(a) = 80. Increased fluorescence detection by the distal end of the diffuser relative to the center section is also demonstrated. Validation of these results was performed by creating phantoms consisting of layered fluorescent regions. Diffusers were inserted into these layered phantoms and fluorescence spectra were collected. Fits to these spectra show quantitative agreement between simulated fluorescence collection sensitivities and experimental results. These results will be applicable to the use of diffusers as detectors for dosimetry in interstitial photodynamic therapy.

  2. Efficient fluorescence energy transfer system between CdTe-doped silica nanoparticles and gold nanoparticles for turn-on fluorescence detection of melamine.

    Science.gov (United States)

    Gao, Feng; Ye, Qingqing; Cui, Peng; Zhang, Lu

    2012-05-09

    We here report an efficient and enhanced fluorescence energy transfer system between confined quantum dots (QDs) by entrapping CdTe into the mesoporous silica shell (CdTe@SiO₂) as donors and gold nanoparticles (AuNPs) as acceptors. At pH 6.50, the CdTe@SiO₂-AuNPs assemblies coalesce to form larger clusters due to charge neutralization, leading to the fluorescence quenching of CdTe@SiO₂ as a result of energy transfer. As compared with the energy transfer system between unconfined CdTe and AuNPs, the maximum fluorescence quenching efficiency of the proposed system is improved by about 27.0%, and the quenching constant, K(sv), is increased by about 2.4-fold. The enhanced quenching effect largely turns off the fluorescence of CdTe@SiO₂ and provides an optimal "off-state" for sensitive "turn-on" assay. In the present study, upon addition of melamine, the weak fluorescence system of CdTe@SiO₂-AuNPs is enhanced due to the strong interactions between the amino group of melamine and the gold nanoparticles via covalent bond, leading to the release of AuNPs from the surfaces of CdTe@SiO₂; thus, its fluorescence is restored. A "turn-on" fluorimetric method for the detection of melamine is proposed based on the restored fluorescence of the system. Under the optimal conditions, the fluorescence enhanced efficiency shows a linear function against the melamine concentrations ranging from 7.5 × 10⁻⁹ to 3.5 × 10⁻⁷ M (i.e., 1.0-44 ppb). The analytical sensitivity is improved by about 50%, and the detection limit is decreased by 5.0-fold, as compared with the analytical results using the CdTe-AuNPs system. Moreover, the proposed method was successfully applied to the determination of melamine in real samples with excellent recoveries in the range from 97.4 to 104.1%. Such a fluorescence energy transfer system between confined QDs and AuNPs may pave a new way for designing chemo/biosensing.

  3. A Model System for Concurrent Detection of Antigen and Antibody Based on Immunological Fluorescent Method

    Directory of Open Access Journals (Sweden)

    Yuan-Cheng Cao

    2015-01-01

    Full Text Available This paper describes a combined antigen/antibody immunoassay implemented in a 96-well plate using fluorescent spectroscopic method. First, goat anti-human IgG was used to capture human IgG (model antigen; goat anti-human IgG (Cy3 or FITC was used to detect the model antigen; a saturating level of model antigen was then added followed by unlabelled goat anti-human IgG (model antibody; finally, Cy3 labelled rabbit anti-goat IgG was used to detect the model antibody. Two approaches were applied to the concomitant assay to analyze the feasibility. The first approach applied FITC and Cy3 when both targets were present at the same time, resulting in 50 ng/mL of the antibody detection limit and 10 ng/mL of antigen detection limit in the quantitative measurements of target concentration, taking the consideration of FRET efficiency of 68% between donor and acceptor. The sequential approach tended to lower the signal/noise (S/N ratio and the detection of the model antigen (lower than 1 ng/mL had better sensitivity than the model antibody (lower than 50 ng/mL. This combined antigen/antibody method might be useful for combined detection of antigens and antibodies. It will be helpful to screen for both antigen and antibody particularly in the situations of the multiserotype and high-frequency mutant virus infections.

  4. A highly selective chemosensor for colorimetric detection of Hg2+ and fluorescence detection of pH changes in aqueous solution

    International Nuclear Information System (INIS)

    Kavitha, Ramasamy; Stalin, Thambusamy

    2014-01-01

    A naturally existing and unmodified simple chemosensor, 2-hydroxy-1,4-naphthoquinone (2HNQ), was identified and used for both the colorimetric detection of Hg 2+ and the fluorescent (on-off) detection of pH. The distinct color change and quenching of fluorescence emission was visible to the naked eye. More importantly, the chemosensor was used in combination with β-cyclodextrin (β-CD), which enabled the sensor to be solubilized and stabilized in aqueous solutions. The sensor selectively detected Hg 2+ via the stable 1:1 complexation of the CåO and OH groups with Hg 2+ and reflected pH changes in the range from 6 to 12 via a fluorescence on–off response resulting from the deprotonation of the hydroxyl group in 2HNQ. - Highlights: • The 2-Hydroxy-1,4-Naphthoquinone (2HNQ) chemosensor is capable of both colorimetric detection of Hg 2+ and a fluorescence on-off response to pH. • The distinct color change and quenching of fluorescence emission are detectable with the naked eye. • The on– off fluorescence response in the pH range from 6– to 12 is due to the deprotonation of the hydroxyl group in 2HNQ

  5. One-pot synthesis of gold nanoclusters with bright red fluorescence and good biorecognition abilities for visualization fluorescence enhancement detection of E. coli.

    Science.gov (United States)

    Liu, Jiali; Lu, Lili; Xu, Suying; Wang, Leyu

    2015-03-01

    A facile one-pot strategy was developed for the synthesis of lysozyme functionalized fluorescence gold nanoclusters (AuNCs). The lysozymes added to reduce Au(3+) ions and stabilize the AuNCs during the synthesis were coated on the AuNCs surface and retained their specific recognition ability for bacteria such as Escherichia coli (E. coli). Based on such ability, these AuNCs were specifically attached onto the surface of E. coli, which resulted in great red fluorescence enhancement. Nevertheless, the bovine serum albumin (BSA) stabilized AuNCs could not recognize E. coli and no fluorescence enhancement was observed. Upon the addition of E. coli, the red fluorescence intensity of lysozyme-AuNCs was enhanced linearly over the range of 2.4×10(4) -6.0×10(6) CFU/mL of E. coli with high sensitivity (LOD=2.0×10(4) CFU/mL, S/N=3). The visualization fluorescence evolution may enable the rapid and real-time detection of bacteria. This study may be extended to other functional proteins such as antibody, enzyme, and peptide functionalized nanoclusters while retaining the bioactivity of coating proteins and find wide applications in the fields of biochemistry and biomedicine. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Detection of Organic Matter in Greenland Ice Cores by Deep-UV Fluorescence

    Science.gov (United States)

    Willis, M.; Malaska, M.; Wanger, G.; Bhartia, R.; Eshelman, E.; Abbey, W.; Priscu, J. C.

    2017-12-01

    The Greenland Ice Sheet is an Earthly analog for icy ocean worlds in the outer Solar System. Future missions to such worlds including Europa, Enceladus, and Titan may potentially include spectroscopic instrumentation to examine the surface/subsurface. The primary goal of our research is to test deep UV/Raman systems for in the situ detection and localization of organics in ice. As part of this effort we used a deep-UV fluorescence instrument able to detect naturally fluorescent biological materials such as aromatic molecules found in proteins and whole cells. We correlated these data with more traditional downstream analyses of organic material in natural ices. Supraglacial ice cores (2-4 m) were collected from several sites on the southwest outlet of the Greenland Ice Sheet using a 14-cm fluid-free mechanical coring system. Repeat spectral mapping data were initially collected longitudinally on uncut core sections. Cores were then cut into 2 cm thick sections along the longitudinal axis, slowly melted and analyzed for total organic carbon (TOC), total dissolved nitrogen (TDN), and bacterial density. These data reveal a spatial correlation between organic matter concentration, cell density, and the deep UV fluorescence maps. Our results provide a profile of the organics embedded within the ice from the top surface into the glacial subsurface, and the TOC:TDN data from the clean interior of the cores are indicative of a biological origin. This work provides a background dataset for future work to characterize organic carbon in the Greenland Ice Sheet and validation of novel instrumentation for in situ data collection on icy bodies.

  7. Non-Invasive Detection of Lung Inflammation by Near-Infrared Fluorescence Imaging Using Bimodal Liposomes.

    Science.gov (United States)

    Desu, Hari R; Wood, George C; Thoma, Laura A

    2016-01-01

    Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome results in respiratory obstruction and severe lung inflammation. Critical characteristics of ALI are alveolar edema, infiltration of leukocytes (neutrophils and monocytes), release of pro-inflammatory cytokines and chemokines into broncho-alveolar lavage fluid, and activation of integrin receptors. The purpose of the study was to demonstrate non-invasive detection of lung inflammation using integrin receptor targeted fluorescence liposomes. An inflammation similar to that observed in ALI was elicited in rodents by intra-tracheal instillation of interleukin-1beta (IL-1beta). Cyclic arginine glycine-(D)-aspartic acid-peptide (cRGD-peptide) grafted fluorescence liposomes were administered to ALI induced male Sprague-Dawley rats for targeting lung integrin receptors. Near-infrared fluorescence imaging (NIRFI) was applied for visualization and quantitation of lung inflammation. NIRFI signals were correlated with inflammatory cellular and biochemical markers of lungs. A positive correlation was observed between NIRF signals and lung inflammation markers. Compared to control group, an intense NIRF signal was observed in ALI induced rats in the window 6-24 h post-IL-1beta instillation. Interaction of integrin receptors with targeted liposomes was assumed to contribute to intense NIRF signal. RT-PCR studies showed an elevated lung expression of alphavbeta5 integrin receptors, 12 h post-IL-1beta instillation. In vitro studies demonstrated integrin receptor specificity of targeted liposomes. These targeted liposomes showed binding to alphavbeta5 integrin receptors expressed on alveolar cells. Non-invasive detection of lung inflammation was demonstrated using a combination of integrin receptor targeting and NIRFI.

  8. Selective detection of Mg2+ ions via enhanced fluorescence emission using Au–DNA nanocomposites

    Directory of Open Access Journals (Sweden)

    Tanushree Basu

    2017-04-01

    Full Text Available The biophysical properties of DNA-modified Au nanoparticles (AuNPs have attracted a great deal of research interest for various applications in biosensing. AuNPs have strong binding capability to the phosphate and sugar groups in DNA, rendering unique physicochemical properties for detection of metal ions. The formation of Au–DNA nanocomposites is evident from the observed changes in the optical absorption, plasmon band, zeta potential, DLS particle size distribution, as well as TEM and AFM surface morphology analysis. Circular dichroism studies also revealed that DNA-functionalized AuNP binding caused a conformational change in the DNA structure. Due to the size and shape dependent plasmonic interactions of AuNPs (33–78 nm with DNA, the resultant Au–DNA nanocomposites (NCs exhibit superior fluorescence emission due to chemical binding with Ca2+, Fe2+ and Mg2+ ions. A significant increase in fluorescence emission (λex = 260 nm of Au–DNA NCs was observed after selectively binding with Mg2+ ions (20–800 ppm in an aqueous solution where a minimum of 100 ppm Mg2+ ions was detected based on the linearity of concentration versus fluorescence intensity curve (λem = 400 nm. The effectiveness of Au–DNA nanocomposites was further verified by comparing the known concentration (50–120 ppm of Mg2+ ions in synthetic tap water and a real life sample of Gelusil (300–360 ppm Mg2+, a widely used antacid medicine. Therefore, this method could be a sensitive tool for the estimation of water hardness after careful preparation of a suitably designed Au–DNA nanostructure.

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

    Science.gov (United States)

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

    2018-03-01

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

  10. Detection of ethanol in alcoholic beverages or vapor phase using fluorescent molecules embedded in a nanofibrous polymer.

    Science.gov (United States)

    Akamatsu, Masaaki; Mori, Taizo; Okamoto, Ken; Komatsu, Hirokazu; Kumagai, Ken; Shiratori, Seimei; Yamamura, Masaki; Nabeshima, Tatsuya; Sakai, Hideki; Abe, Masahiko; Hill, Jonathan P; Ariga, Katsuhiko

    2015-03-25

    An alcohol sensor was developed using the solid-state fluorescence emission of terphenyl-ol (TPhOH) derivatives. Admixtures of TPhOH and sodium carbonate exhibited bright sky-blue fluorescence in the solid state upon addition of small quantities of ethanol. A series of terphenol derivatives was synthesized, and the effects of solvent polarities and the structures of these π-conjugated systems on their fluorescence were systematically investigated by using fluorescence spectroscopy. In particular, π-extended TPhOHs and TPhOHs containing electron-withdrawing groups exhibited significant solvatochromism, and fluorescence colors varied from blue to red. Detection of ethanol contents in alcohol beverages (detection limit ∼ 5 v/v %) was demonstrated using different TPhOHs revealing the effect of molecular structure on sensing properties. Ethanol contents in alcoholic beverages could be estimated from the intensity of the fluorescence elicited from the TPhOHs. Moreover, when terphenol and Na2CO3 were combined with a water-absorbent polymer, ethanol could be detected at lower concentrations. Detection of ethanol vapor (8 v/v % in air) was also accomplished using a nanofibrous polymer scaffold as the immobilized sensing film.

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

    Science.gov (United States)

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

    2015-05-20

    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.

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

    Directory of Open Access Journals (Sweden)

    Piotr Wargocki

    2015-05-01

    Full Text Available 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.

  13. [Determination of emamectin benzoate residue in vegetables by high performance liquid chromatography with fluorescence detection].

    Science.gov (United States)

    Zhang, Yan; Wu, Yinliang; Hu, Jiye; Wang, Hongwei; Pan, Canping; Liu, Fengmao

    2008-01-01

    A method was developed for the determination of emamectin benzoate residue in cabbage and mushroom using solid-phase extraction (SPE) and high performance liquid chromatography (HPLC) with fluorescence detection. The sample was extracted with ethyl acetate. Further cleanup was performed on a propylsulfonic acid solid phase extraction cartridge, followed by the derivatization with trifluoroacetic anhydride in the presence of N-methylimidazole. The amount of derivatized emamectin benzoate was determined by fluorescence detector after separation by HPLC. The detection limit was 0.10 microg/kg for cabbage and mushroom samples. The recoveries of emamectin benzoate in cabbage and mushroom samples were 78.6%-84.9%. The inter-day relative standard deviation (RSD) and intra-day RSD were 2.7%-6.0% and 3.1%-8.9%, respectively, at the fortified levels of 1.0-20.0 microg/kg. The calibration curve of emamectin benzoate in vegetables at the concentration range of 0.002 mg/L to 0.10 mg/L was linear (r = 0.9999).

  14. Determination of aristolochic acids by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Wang, Yinan; Chan, Wan

    2014-06-25

    Nephrotoxic and carcinogenic aristolochic acids (AAs) are naturally occurring nitrophenanthrene carboxylic acids in the herbal genus Aristolochia. The misuse of AA-containing herbs in preparing slimming drugs has caused hundred of cases of kidney disease in Belgium women in a slimming regime in the early 1990s. Accumulating evidence also suggested that prolong dietary intake of AA-contaminated food is one of the major causes to the Balkan endemic nephropathy that was first observed in the late 1950s. Therefore, analytical methods of high sensitivity are extremely important for safeguarding human exposure to AA-containing herbal medicines, herbal remedies, and food composites. In this paper, we describe the development of a new high-performance liquid chromatography coupled fluorescence detector (HPLC-FLD) method for the sensitive determination of AAs. The method makes use of a novel cysteine-induced denitration reaction that "turns on" the fluorescence of AAs for fluorometric detections. Our results showed that the combination of cysteine-induced denitration and HPLC-FLD analysis allows for sensitive quantification of AA-I and AA-II at detection limits of 27.1 and 25.4 ng/g, respectively. The method was validated and has been successfully applied in quantifying AAs in Chinese herbal medicines.

  15. Rapid Detection of Glycogen Synthase Kinase-3 Activity in Mouse Sperm Using Fluorescent Gel Shift Electrophoresis

    Directory of Open Access Journals (Sweden)

    Hoseok Choi

    2016-04-01

    Full Text Available Assaying the glycogen synthase kinase-3 (GSK3 activity in sperm is of great importance because it is closely implicated in sperm motility and male infertility. While a number of studies on GSK3 activity have relied on labor-intensive immunoblotting to identify phosphorylated GSK3, here we report the simple and rapid detection of GSK3 activity in mouse sperm using conventional agarose gel electrophoresis and a fluorescent peptide substrate. When a dye-tethered and prephosphorylated (primed peptide substrate for GSK3 was employed, a distinct mobility shift in the fluorescent bands on the agarose was observed by GSK3-induced phosphorylation of the primed peptides. The GSK3 activity in mouse testes and sperm were quantifiable by gel shift assay with low sample consumption and were significantly correlated with the expression levels of GSK3 and p-GSK3. We suggest that our assay can be used for reliable and rapid detection of GSK3 activity in cells and tissue extracts.

  16. Fluorescence in situ hybridization detection of cytogenetic abnormalities and prognosis in multiple myeloma

    Directory of Open Access Journals (Sweden)

    Zhou Xu

    2015-01-01

    Full Text Available We evaluated the prognosis of patients with newly diagnosed multiple myeloma (MM and attempted to find a suitable treatment strategy for them. Interphase fluorescence in situ hybridization (FISH detection was performed on 57 patients with MM. The following probes: IgH, p53, 1q21, RB1, and D13S319 specific for the rearrangements of 14q32, 17p13, 1q21 and 13q14 were used. Fluorescent hybridization signals were observed using an Olympus BX60 epifluorescence microscope equipped with filters for detecting fluoroisothiocyanate (FITC, Texas red, and 4'-6-Diamidino-2-phenylindole (DAPI. Triple color clone-specific images were captured using a Quips XL genetic workstation. The mortalities in patients with moderate prognosis (66.7% and poor prognosis (50% were significantly higher compared with that in patients with good prognosis (15%, P<0.05. All the patients in good and moderate prognosis groups achieved complete remission (CR/very good partial remission (VGPR/partial remission (PR, whereas only half of the cases in the poor prognosis group reached this level. Patients 2 supported by autologous hematopoietic stem-cell transplantation presented CR/PR and long survival. For those with poor prognosis, a proper therapeutic regimen and timely transplantation, especially tandem transplantation, was necessary due to the rapid progression and complications.

  17. Sensitive detection of copper ions via ion-responsive fluorescence quenching of engineered porous silicon nanoparticles

    Science.gov (United States)

    Hwang, Jangsun; Hwang, Mintai P.; Choi, Moonhyun; Seo, Youngmin; Jo, Yeonho; Son, Jaewoo; Hong, Jinkee; Choi, Jonghoon

    2016-10-01

    Heavy metal pollution has been a problem since the advent of modern transportation, which despite efforts to curb emissions, continues to play a critical role in environmental pollution. Copper ions (Cu2+), in particular, are one of the more prevalent metals that have widespread detrimental ramifications. From this perspective, a simple and inexpensive method of detecting Cu2+ at the micromolar level would be highly desirable. In this study, we use porous silicon nanoparticles (NPs), obtained via anodic etching of Si wafers, as a basis for undecylenic acid (UDA)- or acrylic acid (AA)-mediated hydrosilylation. The resulting alkyl-terminated porous silicon nanoparticles (APS NPs) have enhanced fluorescence stability and intensity, and importantly, exhibit [Cu2+]-dependent quenching of fluorescence. After determining various aqueous sensing conditions for Cu2+, we demonstrate the use of APS NPs in two separate applications - a standard well-based paper kit and a portable layer-by-layer stick kit. Collectively, we demonstrate the potential of APS NPs in sensors for the effective detection of Cu2+.

  18. A novel polymer probe for Zn(II) detection with ratiometric fluorescence signal

    Science.gov (United States)

    Diao, Haipeng; Guo, Lixia; Liu, Wen; Feng, Liheng

    2018-05-01

    A conjugated polymer probe comprised of fluorene, quinolone and benzothiazole units was designed and synthesized by the Suzuki coupling reaction. Through the studies of photophysical and thermal properties, the polymer displays blue-emitting feature and good thermal stability. A ratiometric fluorescence signal of the probe for Zn(II) was observed in ethanol with a new emission peak at 555 nm. The probe possesses a high selectivity and sensitivity for Zn(II) during familiar metal ions in ethanol. The detection limit of the probe for Zn (II) is up to 10-8 mol/L. The electron distributions of the polymer before and after bonding with Zn (II) were investigated by the Gaussian 09 software, which agreed with the experimental results. Noticeably, based on the color property of the probe with Zn(II), a series of color test paper were developed for visual detecting Zn(II) ions. This work helps to provide a platform or pattern for the development of polymer fluorescence probe in the chemosensor field.

  19. Stepwise multiphoton activation fluorescence reveals a new method of melanin detection

    Science.gov (United States)

    Lai, Zhenhua; Kerimo, Josef; Mega, Yair; DiMarzio, Charles A.

    2013-06-01

    The stepwise multiphoton activated fluorescence (SMPAF) of melanin, activated by a continuous-wave mode near infrared (NIR) laser, reveals a broad spectrum extending from the visible spectra to the NIR and has potential application for a low-cost, reliable method of detecting melanin. SMPAF images of melanin in mouse hair and skin are compared with conventional multiphoton fluorescence microscopy and confocal reflectance microscopy (CRM). By combining CRM with SMPAF, we can locate melanin reliably. However, we have the added benefit of eliminating background interference from other components inside mouse hair and skin. The melanin SMPAF signal from the mouse hair is a mixture of a two-photon process and a third-order process. The melanin SMPAF emission spectrum is activated by a 1505.9-nm laser light, and the resulting spectrum has a peak at 960 nm. The discovery of the emission peak may lead to a more energy-efficient method of background-free melanin detection with less photo-bleaching.

  20. BMVC test, an improved fluorescence assay for detection of malignant pleural effusions

    International Nuclear Information System (INIS)

    Lin, I-Ting; Tsai, Yu-Lin; Kang, Chi-Chih; Huang, Wei-Chun; Wang, Chiung-Lin; Lin, Mei-Ying; Lou, Pei-Jen; Shih, Jin-Yuan; Wang, Hao-Chien; Wu, Huey-Dong; Tsai, Tzu-Hsiu; Jan, I-Shiow; Chang, Ta-Chau

    2014-01-01

    The diagnosis of malignant pleural effusions is an important issue in the management of malignancy patients. Generally, cytologic examination is a routine diagnostic technique. However, morphological interpretation of cytology is sometimes inconclusive. Here an ancillary method named BMVC test is developed for rapid detection of malignant pleural effusion to improve the diagnostic accuracy at low cost. A simple assay kit is designed to collect living cells from clinical pleural effusion and a fluorescence probe, 3,6-Bis(1-methyl-4-vinylpyridinium) carbazole diiodide (BMVC), is used to illuminate malignant cells. The fluorescence intensity is quantitatively analyzed by ImageJ program. This method yields digital numbers for the test results without any grey zone or ambiguities in the current cytology tests due to intra-observer and inter-observer variability. Comparing with results from double-blind cytologic examination, this simple test gives a good discrimination between malignant and benign specimens with sensitivity of 89.4% (42/47) and specificity of 93.3% (56/60) for diagnosis of malignant pleural effusion. BMVC test provides accurate results in a short time period, and the digital output could assist cytologic examination to become more objective and clear-cut. This is a convenient ancillary tool for detection of malignant pleural effusions

  1. Rapid Detection of Glycogen Synthase Kinase-3 Activity in Mouse Sperm Using Fluorescent Gel Shift Electrophoresis

    Science.gov (United States)

    Choi, Hoseok; Choi, Bomi; Seo, Ju Tae; Lee, Kyung Jin; Gye, Myung Chan; Kim, Young-Pil

    2016-01-01

    Assaying the glycogen synthase kinase-3 (GSK3) activity in sperm is of great importance because it is closely implicated in sperm motility and male infertility. While a number of studies on GSK3 activity have relied on labor-intensive immunoblotting to identify phosphorylated GSK3, here we report the simple and rapid detection of GSK3 activity in mouse sperm using conventional agarose gel electrophoresis and a fluorescent peptide substrate. When a dye-tethered and prephosphorylated (primed) peptide substrate for GSK3 was employed, a distinct mobility shift in the fluorescent bands on the agarose was observed by GSK3-induced phosphorylation of the primed peptides. The GSK3 activity in mouse testes and sperm were quantifiable by gel shift assay with low sample consumption and were significantly correlated with the expression levels of GSK3 and p-GSK3. We suggest that our assay can be used for reliable and rapid detection of GSK3 activity in cells and tissue extracts. PMID:27092510

  2. Fabrication of high performance microlenses for an integrated capillary channel electrochromatograph with fluorescence detection

    International Nuclear Information System (INIS)

    Wendt, J. R.; Warren, M. E.; Sweatt, W. C.; Bailey, C. G.; Matzke, C. M.; Arnold, D. W.; Allerman, A. A.; Carter, T. R.; Asbill, R. E.; Samora, S.

    1999-01-01

    We describe the microfabrication of an extremely compact optical system as a key element in an integrated capillary channel electrochromatograph with fluorescence detection. The optical system consists of a vertical cavity surface-emitting laser (VCSEL), two high performance microlenses, and a commercial photodetector. The microlenses are multilevel diffractive optics patterned by electron beam lithography and etched by reactive ion etching in fused silica. The design uses substrate-mode propagation within the fused silica substrate. Two generations of optical subsystems are described. The first generation design has a 6 mm optical length and is integrated directly onto the capillary channel-containing substrate. The second generation design separates the optical system onto its own substrate module and the optical path length is further compressed to 3.5 mm. The first generation design has been tested using direct fluorescence detection with a 750 nm VCSEL pumping a 10 -4 M solution of CY-7 dye. The observed signal-to-noise ratio of better than 100:1 demonstrates that the background signal from scattered pump light is low despite the compact size of the optical system and is adequate for system sensitivity requirements. (c) 1999 American Vacuum Society

  3. Impact of laser excitation intensity on deep UV fluorescence detection in microchip electrophoresis.

    Science.gov (United States)

    Schulze, Philipp; Ludwig, Martin; Belder, Detlev

    2008-12-01

    A high intensity 266 nm continuous wave (cw-) laser developed for material processing was utilised as an excitation source for sensitive native fluorescence detection of unlabelled compounds in MCE. This 120 mW laser was attached via an optical fibre into a commercial epifluorescence microscope. With this MCE set-up we evaluated the impact of laser power on the S/N of aromatic compounds as well as of proteins. Compared with a previous work which used a 4 mW pulsed laser for excitation, improved S/N for small aromatics and to a lesser extent for proteins could be attained. The LOD of the system was determined down to 24 ng/mL for serotonin (113 nM), 24 ng/mL for propranolol (81 nM), 80 ng/mL for tryptophan (392 nM) and 80 ng/mL for an aromatic diol (475 nM). Sensitive protein detection was obtained at concentrations of 5 microg/mL for lysocyme, trypsinogen and chymotrypsinogen (340, 208 and 195 nM, respectively). Finally, a comparison of the cw- with a pulsed 266 nm laser, operating at the same average power, showed a higher attainable sensitivity of the cw-laser. This can be attributed to fluorescence saturation and photobleaching effects of the pulsed laser at high pulse energies.

  4. New Concepts of Fluorescent Probes for Specific Detection of DNA Sequences: Bis-Modified Oligonucleotides in Excimer and Exciplex Detection

    Directory of Open Access Journals (Sweden)

    Gbaj A

    2009-01-01

    Full Text Available The detection of single base mismatches in DNA is important for diagnostics, treatment of genetic diseases, and identification of single nucleotide polymorphisms. Highly sensitive, specific assays are needed to investigate genetic samples from patients. The use of a simple fluorescent nucleoside analogue in detection of DNA sequence and point mutations by hybridisation in solution is described in this study. The 5’-bispyrene and 3’-naphthalene oligonucleotide probes form an exciplex on hybridisation to target in water and the 5’-bispyrene oligonucleotide alone is an adequate probe to determine concentration of target present. It was also indicated that this system has a potential to identify mismatches and insertions. The aim of this work was to investigate experimental structures and conditions that permit strong exciplex emission for nucleic acid detectors, and show how such exciplexes can register the presence of mismatches as required in SNP analysis. This study revealed that the hybridisation of 5'-bispyrenyl fluorophore to a DNA target results in formation of a fluorescent probe with high signal intensity change and specificity for detecting a complementary target in a homogeneous system. Detection of SNP mutations using this split-probe system is a highly specific, simple, and accessible method to meet the rigorous requirements of pharmacogenomic studies. Thus, it is possible for the system to act as SNP detectors and it shows promise for future applications in genetic testing.

  5. Simple fluorescence-based detection of protein kinase A activity using a molecular beacon probe.

    Science.gov (United States)

    Ma, Changbei; Lv, Xiaoyuan; Wang, Kemin; Jin, Shunxin; Liu, Haisheng; Wu, Kefeng; Zeng, Weimin

    2017-11-02

    Protein kinase A was detected by quantifying the amount of ATP used after a protein kinase reaction. The ATP assay was performed using the T4 DNA ligase and a molecular beacon (MB). In the presence of ATP, DNA ligase catalyzed the ligation of short DNA. The ligation product then hybridized to MB, resulting in a fluorescence enhancement of the MB. This assay was capable of determining protein kinase A in the range of 12.5∼150 nM, with a detection limit of 1.25 nM. Furthermore, this assay could also be used to investigate the effect of genistein on protein kinase A. It was a universal, non-radioisotopic, and homogeneous method for assaying protein kinase A.

  6. A highly flexible polymerization technique to prepare fluorescent nanospheres for trace ammonia detection

    International Nuclear Information System (INIS)

    Waich, K.; Sandholzer, M.; Mayr, T.; Slugovc, C.; Klimant, I.

    2010-01-01

    The preparation of pH-sensitive nanospheres by emulsion polymerization for the detection of trace levels of ammonia is described. A fluorescent, polymerizable xanthene dye was copolymerized with styrene, crosslinkers and further copolymers aimed at enhancing the sensitivity to obtain materials for sensing of ammonia. A half-seeded technique was used to obtain stable emulsions of the monomers which were cured to obtain nanospheres with covalently attached active components. The nanospheres were embedded in a silicon matrix and the sensor films obtained were investigated regarding their response to ammonia at concentrations between 25 and 1,000 ppb. Sensors containing polystyrene nanospheres crosslinked with divinylbenzene showed the best performance in ammonia measurements exhibiting detection limits (LODs) of less than 25 ppb ammonia.

  7. Dual emission fluorescent silver nanoclusters for sensitive detection of the biological coenzyme NAD+/NADH.

    Science.gov (United States)

    Yuan, Yufeng; Huang, Kehan; Chang, Mengfang; Qin, Cuifang; Zhang, Sanjun; Pan, Haifeng; Chen, Yan; Xu, Jianhua

    2016-02-01

    Fluorescent silver nanoclusters (Ag NCs) displaying dual-excitation and dual-emission properties have been developed for the specific detection of NAD(+) (nicotinamide adenine dinucleotide, oxidized form). With the increase of NAD(+) concentrations, the longer wavelength emission (with the peak at 550 nm) was gradually quenched due to the strong interactions between the NAD(+) and Ag NCs, whereas the shorter wavelength emission (peaking at 395 nm) was linearly enhanced. More important, the dual-emission intensity ratio (I395/I550), fitting by a single-exponential decay function, can efficiently detect various NAD(+) levels from 100 to 4000 μM, as well as label NAD(+)/NADH (reduced form of NAD) ratios in the range of 1-50. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Fluorescence hyper-spectral imaging to detecting faecal contamination on fresh tomatoes

    Directory of Open Access Journals (Sweden)

    Roberto Romaniello

    2016-03-01

    Full Text Available Faecal contamination of fresh fruits represents a severe danger for human health. Thus some techniques based on microbiological testing were developed to individuate faecal contaminants but those tests do not results efficient because their non-applicability on overall vegetable unity. In this work a methodology based on hyper-spectral fluorescence imaging was developed and tested to detecting faecal contamination on fresh tomatoes. Two image-processing methods were performed to maximise the contrast between the faecal contaminant and tomatoes skin: principal component analysis and band image ratio (BRI. The BRI method allows classifying correctly 70% of contaminated area, with no false-positives in all examined cases. Thus, the developed methodology can be employed for a fast and effective detection of faecal contamination on fresh tomatoes.

  9. Confined detection volume of fluorescence correlation spectroscopy by bare fiber probes.

    Science.gov (United States)

    Lu, Guowei; Lei, Franck H; Angiboust, Jean-François; Manfait, Michel

    2010-04-01

    A fiber-tip-based near-field fluorescence correlation spectroscopy (FCS) has been developed for confining the detection volume to sub-diffraction-limited dimensions. This near-field FCS is based on near-field illumination by coupling a scanning near-field optical microscope (SNOM) to a conventional confocal FCS. Single-molecule FCS analysis at 100 nM Rhodamine 6G has been achieved by using bare chemically etched, tapered fiber tips. The detection volume under control of the SNOM system has been reduced over one order of magnitude compared to that of the conventional confocal FCS. Related factors influencing the near-field FCS performance are investigated and discussed in detail. In this proof-of-principle study, the preliminary experimental results suggest that the fiber-tip-based near-field FCS might be a good alternative to realize localized analysis at the single-molecule level.

  10. Sensitive fluorescence on-off probes for the fast detection of a chemical warfare agent mimic.

    Science.gov (United States)

    Khan, Muhammad Shar Jhahan; Wang, Ya-Wen; Senge, Mathias O; Peng, Yu

    2018-01-15

    Two highly sensitive probes bearing a nucleophilic imine moiety have been utilized for the selective detection of chemical warfare agent (CWA) mimics. Diethyl chlorophosphate (DCP) was used as mimic CWAs. Both iminocoumarin-benzothiazole-based probes not only demonstrated a remarkable fluorescence ON-OFF response and good recognition, but also exhibited fast response times (10s) along with color changes upon addition of DCP. Limits of detection for the two sensors 1 and 2 were calculated as 0.065μM and 0.21μM, respectively, which are much lower than most other reported probes. These two probes not only show high sensitivity and selectivity in solution, but can also be applied for the recognition of DCP in the gas state, with significant color changes easily observed by the naked eye. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Amplified fluorescent aptasensor through catalytic recycling for highly sensitive detection of ochratoxin A.

    Science.gov (United States)

    Wei, Yin; Zhang, Ji; Wang, Xu; Duan, Yixiang

    2015-03-15

    This paper describes a novel approach utilizing nano-graphite-aptamer hybrid and DNase I for the amplified detection of ochratoxin A (OTA) for the first time. Nano-graphite can effectively quench the fluorescence of carboxyfluorescein (FAM) labeled OTA specific aptamer due to their strong π-π; stacking interactions; while upon OTA addition, it will bind with aptamer to fold into an OTA-aptamerG-quadruplex structure, which does not adsorb on the surface of nano-graphite and thus retains the dye fluorescence. Meanwhile, the G-quadruplex structure can be cleaved by DNase I, and in such case OTA is delivered from the complex. The released OTA then binds other FAM-labeled aptamers on the nano-graphite surface, and touches off another target recycling, resulting in the successive release of dye-labeled aptamers from the nano-graphite, which leads to significant amplification of the signal. Under the optimized conditions, the present amplified sensing system exhibits high sensitivity toward OTA with a limit of detection of 20nM (practical measurement), which is about 100-fold higher than that of traditional unamplified homogeneous assay. Our developed method also showed high selectivity against other interference molecules and can be applied for the detection of OTA in real red wine samples. The proposed assay is simple, cost-effective, and might open a door for the development of new assays for other biomolecules. This aptasensor is of great practical importance in food safety and could be widely extended to the detection of other toxins by replacing the sequence of the recognition aptamer. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Highly sensitive ratiometric detection of heparin and its oversulfated chondroitin sulfate contaminant by fluorescent peptidyl probe.

    Science.gov (United States)

    Mehta, Pramod Kumar; Lee, Hyeri; Lee, Keun-Hyeung

    2017-05-15

    The selective and sensitive detection of heparin, an anticoagulant in clinics as well as its contaminant oversulfated chondroitin sulfate (OSCS) is of great importance. We first reported a ratiometric sensing method for heparin as well as OSCS contaminants in heparin using a fluorescent peptidyl probe (Pep1, pyrene-GSRKR) and heparin-digestive enzyme. Pep1 exhibited a highly sensitive ratiometric response to nanomolar concentration of heparin in aqueous solution over a wide pH range (2~11) and showed highly selective ratiometric response to heparin among biological competitors such as hyaluronic acid and chondroitin sulfate. Pep1 showed a linear ratiometric response to nanomolar concentrations of heparin in aqueous solutions and in human serum samples. The detection limit for heparin was calculated to be 2.46nM (R 2 =0.99) in aqueous solutions, 2.98nM (R 2 =0.98) in 1% serum samples, and 3.43nM (R 2 =0.99) in 5% serum samples. Pep1 was applied to detect the contaminated OSCS in heparin with heparinase I, II, and III, respectively. The ratiometric sensing method using Pep1 and heparinase II was highly sensitive, fast, and efficient for the detection of OSCS contaminant in heparin. Pep1 with heparinase II could detect as low as 0.0001% (w/w) of OSCS in heparin by a ratiometric response. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Detection and Interpretation of Fluorescence Signals Generated by Excitable Cells and Tissues

    Science.gov (United States)

    Costantino, Anthony J.

    Part 1: High-Sensitivity Amplifiers for Detecting Fluorescence . Monitoring electrical activity and Cai 2+ transients in biological tissues and individual cells increasingly utilizes optical sensors based on voltage-dependent and Cai 2+-dependent fluorescent dyes. However, achieving satisfactory signal-to-noise ratios (SNR) often requires increased illumination intensities and/or dye concentrations, which results in photo-toxicity, photo-bleaching and other adverse effects limiting the utility of optical recordings. The most challenging are the recordings from individual cardiac myocytes and neurons. Here we demonstrate that by optimizing a conventional transimpedance topology one can achieve a 10-20 fold increase of sensitivity with photodiode-based recording systems (dependent on application). We provide a detailed comparative analysis of the dynamic and noise characteristics of different transimpedance amplifier topologies as well as the example(s) of their practical implementation. Part 2: Light-Scattering Models for Interpretation of Fluorescence Data. Current interest in understanding light transport in cardiac tissue has been motivated in part by increased use of voltage-sensitive and Ca i2+-sensitive fluorescent probes to map electrical impulse propagation and Cai2+-transients in the heart. The fluorescent signals are recorded using such probes represent contributions from different layers of myocardial tissue and are greatly affected by light scattering. The interpretation of these signals thus requires deconvolution which would not be possible without detailed models of light transport in the respective tissue. Which involves the experimental measurements of the absorption, scattering, and anisotropy coefficients, mua, mu s, and g respectively. The aim of the second part of our thesis was to derive a new method for deriving these parameters from high spatial resolution measurements of forward-directed flux (FDF). To this end, we carried out high spatial

  14. A turn-on fluorescent rhodamine-acyl hydrazide for selective detection of Cu{sup 2+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jung Won; Jeong, Hyuk; Lee, Min Hee [Dept. of Chemistry, Sookmyung Women' s University, Seoul (Korea, Republic of)

    2017-03-15

    We present a rhodamine-based probe that can detect Cu{sup 2+} ions via Cu{sup 2+}-promoted hydrolysis in aqueous solutions. In solution, the probe is non-fluorescent and colorless, but gives a strong fluorescence at 586 nm and shows a color change to pink on the addition of Cu{sup 2+} ions. We demonstrate that the rhodamine-based probe undergoes Cu{sup 2+}-promoted hydrolysis with a moderate reaction time (within 3 min) and provides a fluorescence off–on change, even in the presence of other competitive metal ions. The rhodamine-based probe shows a linear correlation between increasing fluorescence at 586 nm and the Cu{sup 2+} concentration, and can detect Cu{sup 2+} at nanomolar levels (10 nM) in CH{sub 3}CN:H{sub 2}O (v/v, 90:10)

  15. Highly selective and sensitive detection of Cu2+ with lysine enhancing bovine serum albumin modified-carbon dots fluorescent probe.

    Science.gov (United States)

    Liu, Jia-Ming; Lin, Li-ping; Wang, Xin-Xing; Lin, Shao-Qin; Cai, Wen-Lian; Zhang, Li-Hong; Zheng, Zhi-Yong

    2012-06-07

    Based on the ability of lysine (Lys) to enhance the fluorescence intensity of bovine serum albumin modified-carbon dots (CDs-BSA) to decrease surface defects and quench fluorescence of the CDs-BSA-Lys system in the presence of Cu(2+) under conditions of phosphate buffer (PBS, pH = 5.0) at 45 °C for 10 min, a sensitive Lys enhancing CDs-BSA fluorescent probe was designed. The environment-friendly, simple, rapid, selective and sensitive fluorescent probe has been utilized to detect Cu(2+) in hair and tap water samples and it achieved consistent results with those obtained by inductively coupled plasma mass spectroscopy (ICP-MS). The mechanism of the proposed assay for the detection of Cu(2+) is discussed.

  16. Turn-on fluorescence sensor based on single-walled-carbon-nanohorn-peptide complex for the detection of thrombin.

    Science.gov (United States)

    Zhu, Shuyun; Liu, Zhongyuan; Hu, Lianzhe; Yuan, Yali; Xu, Guobao

    2012-12-14

    Proteases play a central role in several widespread diseases. Thus, there is a great need for the fast and sensitive detection of various proteolytic enzymes. Herein, we have developed a carbon nanotube (CNT)-based protease biosensing platform that uses peptides as a fluorescence probe for the first time. Single-walled carbon nanohorns (SWCNHs) and thrombin were used to demonstrate this detection strategy. SWCNHs can adsorb a fluorescein-based dye (FAM)-labeled peptide (FAM-pep) and quench the fluorescence of FAM. In contrast, thrombin can cleave FAM-pep on SWCNHs and recover the fluorescence of FAM, which allows the sensitive detection of thrombin. This biosensor has a high sensitivity and selectivity toward thrombin, with a detection limit of 100 pM. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Selective detection of Co2+ by fluorescent nano probe: Diagnostic approach for analysis of environmental samples and biological activities

    Science.gov (United States)

    Mahajan, Prasad G.; Dige, Nilam C.; Desai, Netaji K.; Patil, Shivajirao R.; Kondalkar, Vijay V.; Hong, Seong-Karp; Lee, Ki Hwan

    2018-06-01

    Nowadays scientist over the world are engaging to put forth improved methods to detect metal ion in an aqueous medium based on fluorescence studies. A simple, selective and sensitive method was proposed for detection of Co2+ ion using fluorescent organic nanoparticles. We synthesized a fluorescent small molecule viz. 4,4‧-{benzene-1,4-diylbis-[(Z)methylylidenenitrilo]}dibenzoic acid (BMBA) to explore its suitability as sensor for Co2+ ion and biocompatibility in form of nanoparticles. Fluorescence nanoparticles (BMBANPs) prepared by simple reprecipitation method. Aggregation induced enhanced emission of BMBANPs exhibits the narrower particle size of 68 nm and sphere shape morphology. The selective fluorescence quenching was observed by addition of Co2+ and does not affected by presence of other coexisting ion solutions. The photo-physical properties, viz. UV-absorption, fluorescence emission, and lifetime measurements are in support of ligand-metal interaction followed by static fluorescence quenching phenomenon in emission of BMBANPs. Finally, we develop a simple analytical method for selective and sensitive determination of Co2+ ion in environmental samples. The cell culture E. coli, Bacillus sps., and M. tuberculosis H37RV strain in the vicinity of BMBANPs indicates virtuous anti-bacterial and anti-tuberculosis activity which is of additional novel application shown by prepared nanoparticles.

  18. A “turn-on” fluorescent microbead sensor for detecting nitric oxide

    Directory of Open Access Journals (Sweden)

    Yang LH

    2014-12-01

    Full Text Available Lan-Hee Yang,1,2 Dong June Ahn,3 Eunhae Koo1 1Advanced Materials Convergence Division, Korea Institute of Ceramic Engineering and Technology, Seoul, Republic of Korea; 2Department of Biomicrosystem Technology, Korea University, Seoul, Republic of Korea; 3Departments of Biomicrosystem Technology, Chemical & Biological Engineering, KU-KIST Graduate School, Korea University, Seoul, Republic of Korea Abstract: Nitric oxide (NO is a messenger molecule involved in numerous physical and pathological processes in biological systems. Therefore, the development of a highly sensitive material able to detect NO in vivo is a key step in treating cardiovascular and a number of types of cancer-related diseases, as well as neurological dysfunction. Here we describe the development of a fluorescent probe using microbeads to enhance the fluorescence signal. Microbeads are infused with the fluorophore, dansyl-piperazine (Ds-pip, and quenched when the fluorophore is coordinated with a rhodium (Rh-complex, ie, Rh2(AcO-4(Ds-pip. In contrast, they are able to fluoresce when the transition-metal complex is replaced by NO. To confirm the “on/off” mechanism for detecting NO, we investigated the structural molecular properties using the Fritz Haber Institute ab initio molecular simulations (FHI-AIMS package. According to the binding energy calculation, NO molecules bind more strongly and rapidly with the Rh-core of the Rh-complex than with Ds-pip. This suggests that NO can bond strongly with the Rh-core and replace Ds-pip, even though Ds-pip is already near the Rh-core. However, the recovery process takes longer than the quenching process because the recovery process needs to overcome the energy barrier for formation of the transition state complex, ie, NO-(AcO-4-(Ds-pip. Further, we confirm that the Rh-complex with the Ds-pip structure has too small an energy gap to give off visible light from the highest unoccupied molecular orbital/lowest unoccupied molecular

  19. A Fluorescent Molecular Probe for the Detection of Hydrogen Based on Oxidative Addition Reactions with Crabtree-Type Hydrogenation Catalysts.

    Science.gov (United States)

    Kos, Pavlo; Plenio, Herbert

    2015-11-02

    A Crabtree-type Ir(I) complex tagged with a fluorescent dye (bodipy) was synthesized. The oxidative addition of H2 converts the weakly fluorescent Ir(I) complex (Φ=0.038) into a highly fluorescent Ir(III) species (Φ=0.51). This fluorogenic reaction can be utilized for the detection of H2 and to probe the oxidative addition step in the catalytic hydrogenation of olefins. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Functionalization of embedded thiol-ene waveguides for evanescent wave induced fluorescence detection in a microfluidic device

    DEFF Research Database (Denmark)

    Feidenhans'l, Nikolaj Agentoft; Jensen, Thomas Glasdam; Lafleur, Josiane P.

    2013-01-01

    We demonstrate the use of functional surface groups inherently present on off-stoichiometric thiol−ene polymers, for site-specific immobilization of biomolecules and detection by evanescent wave-induced fluorescence. An optofluidic chip featuring an embedded thiol−ene waveguide was selectively...... functionalized with biotin using photografting. The biotin was used for immobilization of fluorescently labelled streptavidin, and experiments revealed a linear correlation between streptavidin concentration and fluorescent intensity. To further demonstrate the attractiveness of using thiol−ene for optofluidic...

  1. Comment on ’Single Pentacene Molecules Detected by Fluorescence Excitation in a P-Terphenyl Crystal’

    Science.gov (United States)

    1990-12-10

    8217 NO 11 TITLE (include Security Classification) Comment on "Single Pentacene Molecules Detected by Fluorescence Excitation in a p-Terphenyl Crystal" 12...8217 {Continue on reverse it necessary and identify by block numboer) Using h--,Ihly efficient Fluorescence excitation spectroscov of individual pentacene ...molecular impurities in p-terphenvl crystals, we have observed that some pentacene defects exhibit spcntaneous spectral jumps in their resonance frequency at

  2. Palladium Nanoparticles-Based Fluorescence Resonance Energy Transfer Aptasensor for Highly Sensitive Detection of Aflatoxin M₁ in Milk.

    Science.gov (United States)

    Li, Hui; Yang, Daibin; Li, Peiwu; Zhang, Qi; Zhang, Wen; Ding, Xiaoxia; Mao, Jin; Wu, Jing

    2017-10-13

    A highly sensitive aptasensor for aflatoxin M₁ (AFM₁) detection was constructed based on fluorescence resonance energy transfer (FRET) between 5-carboxyfluorescein (FAM) and palladium nanoparticles (PdNPs). PdNPs (33 nm) were synthesized through a seed-mediated growth method and exhibited broad and strong absorption in the whole ultraviolet-visible (UV-Vis) range. The strong coordination interaction between nitrogen functional groups of the AFM₁ aptamer and PdNPs brought FAM and PdNPs in close proximity, which resulted in the fluorescence quenching of FAM to a maximum extent of 95%. The non-specific fluorescence quenching caused by PdNPs towards fluorescein was negligible. After the introduction of AFM₁ into the FAM-AFM₁ aptamer-PdNPs FRET system, the AFM₁ aptamer preferentially combined with AFM₁ accompanied by conformational change, which greatly weakened the coordination interaction between the AFM₁ aptamer and PdNPs. Thus, fluorescence recovery of FAM was observed and a linear relationship between the fluorescence recovery and the concentration of AFM₁ was obtained in the range of 5-150 pg/mL in aqueous buffer with the detection limit of 1.5 pg/mL. AFM₁ detection was also realized in milk samples with a linear detection range from 6 pg/mL to 150 pg/mL. The highly sensitive FRET aptasensor with simple configuration shows promising prospect in detecting a variety of food contaminants.

  3. Design of near-infrared fluorescent bioactive conjugated functional iron oxide nanoparticles for optical detection of colon cancer

    Directory of Open Access Journals (Sweden)

    Corem-Salkmon E

    2012-10-01

    Full Text Available Enav Corem-Salkmon, Benny Perlstein, Shlomo MargelThe Institute of Nanotechnology and Advanced Materials, Department of Chemistry, Bar-Ilan University, Ramat-Gan, IsraelBackground: Colon cancer is one of the major causes of death in the Western world. Early detection significantly improves long-term survival for patients with the disease. Near-infrared (NIR fluorescent nanoparticles hold great promise as contrast agents for tumor detection. NIR offers several advantages for bioimaging compared with fluorescence in the visible spectrum, ie, lower autofluorescence of biological tissues, lower absorbance, and consequently deeper penetration into biomatrices.Methods and results: NIR fluorescent iron oxide nanoparticles with a narrow size distribution were prepared by nucleation, followed by controlled growth of thin iron oxide films onto cyanine NIR dye conjugated gelatin-iron oxide nuclei. For functionalization, and in order to increase the NIR fluorescence intensity, the NIR fluorescent iron oxide nanoparticles obtained were coated with human serum albumin containing cyanine NIR dye. Leakage of the NIR dye from these nanoparticles into phosphate-buffered saline solution containing 4% albumin was not detected. The work presented here is a feasibility study to test the suitability of iron oxide-human serum albumin NIR fluorescent nanoparticles for optical detection of colon cancer. It demonstrates that encapsulation of NIR fluorescent dye within these nanoparticles significantly reduces photobleaching of the dye. Tumor-targeting ligands, peanut agglutinin and anticarcinoembryonic antigen antibodies (αCEA, were covalently conjugated with the NIR fluorescent iron oxide-human serum albumin nanoparticles via a poly(ethylene glycol spacer. Specific colon tumor detection was demonstrated in chicken embryo and mouse models for both nonconjugated and the peanut agglutinin-conjugated or αCEA-conjugated NIR fluorescent iron oxide-human serum albumin

  4. A graphene oxide-based fluorescent aptasensor for the turn-on detection of epithelial tumor marker mucin 1.

    Science.gov (United States)

    He, Yue; Lin, Yi; Tang, Hongwu; Pang, Daiwen

    2012-03-21

    Mucin 1 (MUC1) which presents in epithelial malignancies, is a well-known tumor biomarker. In this paper, a highly sensitive and selective fluorescent aptasensor for Mucin 1 (MUC1) detection is constructed, utilizing graphene oxide (GO) as a quencher which can quench the fluorescence of single-stranded dye-labeled MUC1 specific aptamer. In the absence of MUC1, the adsorption of the dye-labeled aptamer on GO brings the dyes in close proximity to the GO surface resulting in high efficiency quenching of dye fluorescence. Therefore, the fluorescence of the designed aptasensor is completely quenched by GO, and the system shows very low background fluorescence. Conversely, and very importantly, upon the adding of MUC1, the quenched fluorescence is recovered significantly, and MUC1 can be detected in a wide range of 0.04-10 μM with a detection limit of 28 nM and good selectivity. Moreover, the results have also been verified for real sample application by testing 2% serum containing buffer solution spiked with a series of concentrations of MUC1. This journal is © The Royal Society of Chemistry 2012

  5. Real-Time Fluorescence Loop Mediated Isothermal Amplification for the Detection of Acinetobacter baumannii

    Science.gov (United States)

    Wang, Qinqin; Zhou, Yanbin; Li, Shaoli; Zhuo, Chao; Xu, Siqi; Huang, Lixia; Yang, Ling; Liao, Kang

    2013-01-01

    Background Detection of Acinetobacter baumannii has been relying primarily on bacterial culture that often fails to return useful results in time. Although DNA-based assays are more sensitive than bacterial culture in detecting the pathogen, the molecular results are often inconsistent and challenged by doubts on false positives, such as those due to system- and environment-derived contaminations. In addition, these molecular tools require expensive laboratory instruments. Therefore, establishing molecular tools for field use require simpler molecular platforms. The loop-mediated isothermal amplification method is relatively simple and can be improved for better use in a routine clinical bacteriology laboratory. A simple and portable device capable of performing both the amplification and detection (by fluorescence) of LAMP in the same platform has been developed in recent years. This method is referred to as real-time loop-mediated isothermal amplification. In this study, we attempted to utilize this method for rapid detection of A. baumannii. Methodology and Significant Findings Species-specific primers were designed to test the utility of this method. Clinical samples of A. baumannii were used to determine the sensitivity and specificity of this system compared to bacterial culture and a polymerase chain reaction method. All positive samples isolated from sputum were confirmed to be the species of Acinetobacter by 16S rRNA gene sequencing. The RealAmp method was found to be simpler and allowed real-time detection of DNA amplification, and could distinguish A. baumannii from Acinetobacter calcoaceticus and Acinetobacter genomic species 3. DNA was extracted by simple boiling method. Compared to bacterial culture, the sensitivity and specificity of RealAmp in detecting A. baumannii was 98.9% and 75.0%, respectively. Conclusion The RealAmp assay only requires a single unit, and the assay positivity can be verified by visual inspection. Therefore, this assay has

  6. Censoring: a new approach for detection limits in total-reflection X-ray fluorescence

    International Nuclear Information System (INIS)

    Pajek, M.; Kubala-Kukus, A.; Braziewicz, J.

    2004-01-01

    It is shown that the detection limits in the total-reflection X-ray fluorescence (TXRF), which restrict quantification of very low concentrations of trace elements in the samples, can be accounted for using the statistical concept of censoring. We demonstrate that the incomplete TXRF measurements containing the so-called 'nondetects', i.e. the non-measured concentrations falling below the detection limits and represented by the estimated detection limit values, can be viewed as the left random-censored data, which can be further analyzed using the Kaplan-Meier (KM) method correcting for nondetects. Within this approach, which uses the Kaplan-Meier product-limit estimator to obtain the cumulative distribution function corrected for the nondetects, the mean value and median of the detection limit censored concentrations can be estimated in a non-parametric way. The Monte Carlo simulations performed show that the Kaplan-Meier approach yields highly accurate estimates for the mean and median concentrations, being within a few percent with respect to the simulated, uncensored data. This means that the uncertainties of KM estimated mean value and median are limited in fact only by the number of studied samples and not by the applied correction procedure for nondetects itself. On the other hand, it is observed that, in case when the concentration of a given element is not measured in all the samples, simple approaches to estimate a mean concentration value from the data yield erroneous, systematically biased results. The discussed random-left censoring approach was applied to analyze the TXRF detection-limit-censored concentration measurements of trace elements in biomedical samples. We emphasize that the Kaplan-Meier approach allows one to estimate the mean concentrations being substantially below the mean level of detection limits. Consequently, this approach gives a new access to lower the effective detection limits for TXRF method, which is of prime interest for

  7. Performance of a Cyanobacteria Whole Cell-Based Fluorescence Biosensor for Heavy Metal and Pesticide Detection

    Directory of Open Access Journals (Sweden)

    Salmijah Surif

    2013-05-01

    Full Text Available Whole cell biosensors always face the challenge of low stability of biological components and short storage life. This paper reports the effects of poly(2-hydroxyethyl methacrylate (pHEMA immobilization on a whole cell fluorescence biosensor for the detection of heavy metals (Cu, Pb, Cd, and pesticides (dichlorophenoxyacetic acid (2,4-D, and chlorpyrifos. The biosensor was produced by entrapping the cyanobacterium Anabaena torulosa on a cellulose membrane, followed by applying a layer of pHEMA, and attaching it to a well. The well was then fixed to an optical probe which was connected to a fluorescence spectrophotometer and an electronic reader. The optimization of the biosensor using several factors such as amount of HEMA and drying temperature were undertaken. The detection limits of biosensor without pHEMA for Cu, Cd, Pb, 2,4-D and chlorpyrifos were 1.195, 0.027, 0.0100, 0.025 and 0.025 µg/L respectively. The presence of pHEMA increased the limits of detection to 1.410, 0.250, 0.500, 0.235 and 0.117 µg/L respectively. pHEMA is known to enhance the reproducibility of the biosensor with average relative standard deviation (RSD of ±1.76% for all the pollutants tested, 48% better than the biosensor without pHEMA (RSD = ±3.73%. In storability test with Cu 5 µg/L, the biosensor with pHEMA performed 11.5% better than the test without pHEMA on day-10 and 5.2% better on day-25. pHEMA is therefore a good candidate to be used in whole cell biosensors as it increases reproducibility and enhances biosensor storability.

  8. Detection of Biomass in New York City Aerosols: Light Scattering and Optical Fluorescence Techniques

    Science.gov (United States)

    Niebauer, M.; Alimova, A.; Katz, A.; Xu, M.; Rudolph, E.; Steiner, J.; Alfano, R. R.

    2005-12-01

    Optical spectroscopy is an ideal method for detecting bacteria and spores in real time. Optical fluorescence spectroscopy examination of New York City aerosols is used to quantify the mass of bacteria spores present in air masses collected at 14 liters/minute onto silica fiber filters, and on silica fiber ribbons using an Environmental Beta Attenuation Monitor manufactured by MetOne Instruments configured for the PM2.5 fraction. Dipicolinic acid (DPA), a molecule found primarily in bacterial spores, is the most characteristic component of spores in trial experiments on over 200 collected aerosol samples. DPA is extracted from the spores using a heat bath and chelated with Terbium. The DPA:Tb is detected by measuring its characteristic fluorescence with emission bands at 490, 545 and 585 nm for 270 nm excitation. Light scattering also measures the size distribution for a number of a variety of bacteria - Bacillus subtilis (rod shaped), Staphylococcus aureus (spherical) and Pseudomonas aeruginosa (short rods) establishing that optical techniques satisfactorily distinguish populations based on their variable morphology. Size and morphology are obtained by applying a variation of the Gaussian Ray Approximation theory of anomalous diffraction theory to an analysis of the transmission spectra in the range of 0.4 to 1.0 microns. In test experiments, the refractive index of the inner spore core of Bacillus subtilis decreases from 1.51 to 1.39 while the spore radius enlarges from 0.38 to 0.6 micrometers. Optical determinations are verified by oil-immersion techniques and by scanning electron microscope measurements. Characterization of spores, germinating spore materials, and bacteria is considered vital to tracing bacteria in the environment, for the development of life-detection systems for planetary exploration, monitoring pathogens in environmental systems, and for the preparation of anti-terrorism strategies.

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

    Science.gov (United States)

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

    2012-07-03

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

  10. Detection and Analysis of Enamel Cracks by Quantitative Light-induced Fluorescence Technology.

    Science.gov (United States)

    Jun, Mi-Kyoung; Ku, Hye-Min; Kim, Euiseong; Kim, Hee-Eun; Kwon, Ho-Keun; Kim, Baek-Il

    2016-03-01

    The ability to accurately detect tooth cracks and quantify their depth would allow the prediction of crack progression and treatment success. The aim of this in vitro study was to determine the capabilities of quantitative light-induced fluorescence (QLF) technology in the detection of enamel cracks. Ninety-six extracted human teeth were selected for examining naturally existing or suspected cracked teeth surfaces using a photocuring unit. QLF performed with a digital camera (QLF-D) images were used to assess the ability to detect enamel cracks based on the maximum fluorescence loss value (ΔFmax, %), which was then analyzed using the QLF-D software. A histologic evaluation was then performed in which the samples were sectioned and observed with the aid of a polarized light microscope. The relationship between ΔFmax and the histology findings was assessed based on the Spearman rank correlation. The sensitivity and specificity were calculated to evaluate the validity of using QLF-D to analyze enamel inner-half cracks and cracks extending to the dentin-enamel junction. There was a strong correlation between the results of histologic evaluations of enamel cracks and the ΔFmax value, with a correlation coefficient of 0.84. The diagnostic accuracy of QLF-D had a sensitivity of 0.87 and a specificity of 0.98 for enamel inner-half cracks and a sensitivity of 0.90 and a specificity of 1.0 for cracks extending to the dentin-enamel junction. These results indicate that QLF technology would be a useful clinical tool for diagnosing enamel cracks, especially given that this is a nondestructive method. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  11. Censoring approach to the detection limits in X-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Pajek, M.; Kubala-Kukus, A.

    2004-01-01

    We demonstrate that the effect of detection limits in the X-ray fluorescence analysis (XRF), which limits the determination of very low concentrations of trace elements and results in appearance of the so-called 'nondetects', can be accounted for using the statistical concept of censoring. More precisely, the results of such measurements can be viewed as the left random censored data, which can further be analyzed using the Kaplan-Meier method correcting the data for the presence of nondetects. Using this approach, the results of measured, detection limit censored concentrations can be interpreted in a nonparametric manner including the correction for the nondetects, i.e. the measurements in which the concentrations were found to be below the actual detection limits. Moreover, using the Monte Carlo simulation technique we show that by using the Kaplan-Meier approach the corrected mean concentrations for a population of the samples can be estimated within a few percent uncertainties with respect of the simulated, uncensored data. This practically means that the final uncertainties of estimated mean values are limited in fact by the number of studied samples and not by the correction procedure itself. The discussed random-left censoring approach was applied to analyze the XRF detection-limit-censored concentration measurements of trace elements in biomedical samples

  12. Fluorescence In Situ Hybridization for MicroRNA Detection in Archived Oral Cancer Tissues

    Directory of Open Access Journals (Sweden)

    Zonggao Shi

    2012-01-01

    Full Text Available The noncoding RNA designated as microRNA (miRNA is a large group of small single-stranded regulatory RNA and has generated wide-spread interest in human disease studies. To facilitate delineating the role of microRNAs in cancer pathology, we sought to explore the feasibility of detecting microRNA expression in formalin-fixed paraffin-embedded (FFPE tissues. Using FFPE materials, we have compared fluorescent in situ hybridization (FISH procedures to detect miR-146a with (a different synthetic probes: regular custom DNA oligonucleotides versus locked nucleic acid (LNA incorporated DNA oligonucleotides; (b different reporters for the probes: biotin versus digoxigenin (DIG; (c different visualization: traditional versus tyramide signal amplification (TSA system; (d different blocking reagents for endogenous peroxidase. Finally, we performed miR-146a FISH on a commercially available oral cancer tissue microarray, which contains 40 cases of oral squamous cell carcinoma (OSCC and 10 cases of normal epithelia from the human oral cavity. A sample FISH protocol for detecting miR-146a is provided. In summary, we have established reliable in situ hybridization procedures for detecting the expression of microRNA in FFPE oral cancer tissues. This method is an important tool for studies on the involvement of microRNA in oral cancer pathology and may have potential prognostic or diagnostic value.

  13. High sensitivity detection of selenium by laser excited atomic fluorescence spectrometry using electrothermal atomization

    International Nuclear Information System (INIS)

    Heitmann, U.; Hese, A.; Schoknecht, G.; Gries, W.

    1995-01-01

    The high sensitivity detection of the trace element selenium is reported. The analytical method applied is Laser Excited Atomic Fluorescence Spectrometry using Electrothermal Atomization within a graphite furnace atomizer. For the production of tunable laser radiation in the VUV spectral region a laser system was developed which consists of two dye lasers pumped by a Nd:YAG laser. The laser radiations are subsequently frequency doubled and sum frequency mixed by nonlinear optical KDP or BBO crystals, respectively. The system works with a repetition rate of 20 Hz and provides output energies of up to 100 μJ in the VUV at a pulse duration of 5 ns. The analytical investigations were focused on the detection of selenium in aqueous solutions and samples of human whole blood. From measurements on aqueous standards detection limits of 1.5 ng/l for selenium were obtained, with corresponding absolute detected masses of only 15 fg. The linear dynamic range spanned six orders of magnitude and good precision was achieved. In case of human whole blood samples the recovery was found to be within the range of 96% to 104%. The determination of the selenium content yielded medians of [119.5 ± 17.3] μg/l for 200 frozen blood samples taken in 1988 and [109.1 ± 15.6] μg/l for 103 fresh blood samples. (author)

  14. Development and Testing of an Air Fluorescence Imaging System for the Detection of Radiological Contamination

    International Nuclear Information System (INIS)

    Inrig, Elizabeth; Koslowsky, Vern; Andrews, Bob; Dick, Michael; Forget, Patrick; Ing, Harry; Hugron, Roger; Wong, Larry

    2011-01-01

    Detection of radionuclides emitting short-range radiation, such as α and low-energy β particles, has always presented a challenge, particularly when such radionuclides are dispersed over a wide area. In this situation, conventional detection methods require the area of interest to be surveyed using a fragile probe at very close range--a slow, error-prone, and potentially dangerous process that may take many hours for a single room. The instrument under development uses a novel approach by imaging radiation-induced fluorescence in the air surrounding a contaminated area, rather than detecting the radiation directly. A robust and portable system has been designed and built that will allow contaminated areas to be rapidly detected and delineated. The detector incorporates position-sensitive photo-multiplier tubes, UV filters, a fast electronic shutter and an aspherical phase mask that significantly increases the depth-of-field. Preliminary tests have been conducted using sealed 241 Am sources of varying activities and surface areas. The details of the instrument design will be described and the results of recent testing will be presented.

  15. Graphitic Carbon Nitride Nanosheets-Based Ratiometric Fluorescent Probe for Highly Sensitive Detection of H2O2 and Glucose.

    Science.gov (United States)

    Liu, Jin-Wen; Luo, Ying; Wang, Yu-Min; Duan, Lu-Ying; Jiang, Jian-Hui; Yu, Ru-Qin

    2016-12-14

    Graphitic carbon nitride (g-C 3 N 4 ) nanosheets, an emerging graphene-like carbon-based nanomaterial with high fluorescence and large specific surface areas, hold great potential for biosensor applications. Current g-C 3 N 4 nanosheets based fluorescent biosensors majorly rely on single fluorescent intensity reading through fluorescence quenching interactions between the nanosheets and metal ions. Here we report for the first time the development of a novel g-C 3 N 4 nanosheets-based ratiometric fluorescence sensing strategy for highly sensitive detection of H 2 O 2 and glucose. With o-phenylenediamine (OPD) oxidized by H 2 O 2 in the presence of horseradish peroxidase (HRP), the oxidization product can assemble on the g-C 3 N 4 nanosheets through hydrogen bonding and π-π stacking, which effectively quenches the fluorescence of g-C 3 N 4 while delivering a new emission peak. The ratiometric signal variations enable robust and sensitive detection of H 2 O 2 . On the basis of the glucose converting into H 2 O 2 through the catalysis of glucose oxidase, the g-C 3 N 4 -based ratiometric fluorescence sensing platform is also exploited for glucose assay. The developed strategy is demonstrated to give a detection limit of 50 nM for H 2 O 2 and 0.4 μM for glucose, at the same time, it has been successfully used for glucose levels detection in human serum. This strategy may provide a cost-efficient, robust, and high-throughput platform for detecting various species involving H 2 O 2 -generation reactions for biomedical applications.

  16. Development of new photon detection device for Cherenkov and fluorescence radiation

    Directory of Open Access Journals (Sweden)

    Tinti A.

    2013-06-01

    Full Text Available Recent progress on the development of a new solid state detector allowed the use of finely pixelled photocathodes obtained from silicon semiconductors. SiPM detectors seem to be an ideal tool for the detection of Cherenkov and fluorescence light in spite of their not yet resolved criticism for operating temperature and intrinsic noise. The main disadvantage of SiPM in this case is the poor sensitivity in the wavelength range 300-400 nm, where the Cherenkov light and fluorescence radiation are generated. We report on the possibility to realize a new kind of pixelled photodetector based on the use of silicon substrate with carbon nanotube compounds, more sensitive to the near UV radiation. Also if at the very beginning, the development of such detector appears very promising and useful for astroparticle physics, both in the ground based arrays and in the space experiments. The detectors are ready to be operated in conditions of measurements without signal amplification.

  17. Fluorescence detection, enumeration and characterization of single circulating cells in vivo: technology, applications and future prospects

    Science.gov (United States)

    Hartmann, Carolin; Patil, Roshani; Lin, Charles P.; Niedre, Mark

    2018-01-01

    There are many diseases and biological processes that involve circulating cells in the bloodstream, such as cancer metastasis, immunology, reproductive medicine, and stem cell therapies. This has driven significant interest in new technologies for the study of circulating cells in small animal research models and clinically. Most currently used methods require drawing and enriching blood samples from the body, but these suffer from a number of limitations. In contrast, ‘in vivo flow cytometry’ (IVFC) refers to set of technologies that allow study of cells directly in the bloodstream of the organism in vivo. In recent years the IVFC field has grown significantly and new techniques have been developed, including fluorescence microscopy, multi-photon, photo-acoustic, and diffuse fluorescence IVFC. In this paper we review recent technical advances in IVFC, with emphasis on instrumentation, contrast mechanisms, and detection sensitivity. We also describe key applications in biomedical research, including cancer research and immunology. Last, we discuss future directions for IVFC, as well as prospects for broader adoption by the biomedical research community and translation to humans clinically.

  18. Easy and Rapid Detection of Mumps Virus by Live Fluorescent Visualization of Virus-Infected Cells.

    Directory of Open Access Journals (Sweden)

    Tadanobu Takahashi

    Full Text Available Mumps viruses show diverse cytopathic effects (CPEs of infected cells and viral plaque formation (no CPE or no plaque formation in some cases depending on the viral strain, highlighting the difficulty in mumps laboratory studies. In our previous study, a new sialidase substrate, 2-(benzothiazol-2-yl-4-bromophenyl 5-acetamido-3,5-dideoxy-α-D-glycero-D-galacto-2-nonulopyranosidonic acid (BTP3-Neu5Ac, was developed for visualization of sialidase activity. BTP3-Neu5Ac can easily and rapidly perform histochemical fluorescent visualization of influenza viruses and virus-infected cells without an antiviral antibody and cell fixation. In the present study, the potential utility of BTP3-Neu5Ac for rapid detection of mumps virus was demonstrated. BTP3-Neu5Ac could visualize dot-blotted mumps virus, virus-infected cells, and plaques (plaques should be called focuses due to staining of infected cells in this study, even if a CPE was not observed. Furthermore, virus cultivation was possible by direct pick-up from a fluorescent focus. In conventional methods, visible appearance of the CPE and focuses often requires more than 6 days after infection, but the new method with BTP3-Neu5Ac clearly visualized infected cells after 2 days and focuses after 4 days. The BTP3-Neu5Ac assay is a precise, easy, and rapid assay for confirmation and titration of mumps virus.

  19. Indirect fluorescence detection of native amino acids in capillary zone electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Kuhr, W.G.; Yeung, E.S.

    1988-09-01

    Amino acids are but one of several important classes of small chemical compounds in biological chemistry that have an inherent lack of analytically useful physical properties. Amino acids, peptides, fatty acids, sugars, many mono-, di-, and tricarboxylic acids, and phosphorylated intermediates in glycolysis and metabolism show little, if any, UV or visible absorption, fluorescence, or electrochemical activity. As the emphasis of biochemical research shifts to smaller samples where, for example, picomolar quantities of amino acids are analyzed in gas phase protein sequencing or in microliter samples of the extracellular fluid of the mammalian brain, the analytical problem becomes even more challenging due to the small volume of sample available for analysis. In this work, laser-induced fluorescence spectroscopy is performed on-column to detect the bands separated with capillary zone electrophoresis (CZE). CZE is an instrumental form of zone electrophoresis where chemical species are separated purely on the basis of their electrophoretic mobility, since no supporting gel is utilized. Both anions and cations can be separated in the same run because of the large electroosmotic flow generated in small diameter capillaries. This technique has already been used successfully in the rapid, efficient separation of dansyl-amino acids.

  20. Determination of the carbohydrates from Notopterygium forbesii Boiss by HPLC with fluorescence detection.

    Science.gov (United States)

    Zhang, Shijuan; Li, Chunli; Zhou, Guoying; Che, Guodong; You, Jinmao; Suo, Yourui

    2013-09-12

    A sensitive pre-column derivatization method was developed for analysis of carbohydrates by HPLC with fluorescence detection. The introduction of 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) with excellent fluorescence property into the molecules of monosaccharides greatly enhanced the HPLC sensitivity of the analytes. Meanwhile, derivatization with BAAH also greatly increased the hydrophobicity of the monosaccharides and made them elute at increased retention times. The monosaccharides with similar properties therefore could be completely separated due to the increased interaction between the analytes and the column. Component monosaccharides of the polysaccharides obtained from the roots, stems and leaves of Notopterygium forbesii Boiss (NF) were analyzed by the developed method. The results indicated that the polysaccharides of NF were mainly composed of d-galactose and d-glucose. This is the first systematic study of the sugar composition of the polysaccharides of NF. It will be helpful for the quality control of NF. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Mesoporous structured MIPs@CDs fluorescence sensor for highly sensitive detection of TNT.

    Science.gov (United States)

    Xu, Shoufang; Lu, Hongzhi

    2016-11-15

    A facile strategy was developed to prepare mesoporous structured molecularly imprinted polymers capped carbon dots (M-MIPs@CDs) fluorescence sensor for highly sensitive and selective determination of TNT. The strategy using amino-CDs directly as "functional monomer" for imprinting simplify the imprinting process and provide well recognition sites accessibility. The as-prepared M-MIPs@CDs sensor, using periodic mesoporous silica as imprinting matrix, and amino-CDs directly as "functional monomer", exhibited excellent selectivity and sensitivity toward TNT with detection limit of 17nM. The recycling process was sustainable for 10 times without obvious efficiency decrease. The feasibility of the developed method in real samples was successfully evaluated through the analysis of TNT in soil and water samples with satisfactory recoveries of 88.6-95.7%. The method proposed in this work was proved to be a convenient and practical way to prepare high sensitive and selective fluorescence MIPs@CDs sensors. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Detection of Thrombin Based on Fluorescence Energy Transfer between Semiconducting Polymer Dots and BHQ-Labelled Aptamers

    Directory of Open Access Journals (Sweden)

    Yizhang Liu

    2018-02-01

    Full Text Available Carboxyl-functionalized semiconducting polymer dots (Pdots were synthesized as an energy donor by the nanoprecipitation method. A black hole quenching dye (BHQ-labelled thrombin aptamers was used as the energy acceptor, and fluorescence resonance energy transfer between the aptamers and Pdots was used for fluorescence quenching of the Pdots. The addition of thrombin restored the fluorescence intensity. Under the optimized experimental conditions, the fluorescence of the system was restored to the maximum when the concentration of thrombin reached 130 nM, with a linear range of 0–50 nM (R2 = 0.990 and a detection limit of 0.33 nM. This sensor was less disturbed by impurities, showing good specificity and signal response to thrombin, with good application in actual samples. The detection of human serum showed good linearity in the range of 0–30 nM (R2 = 0.997, with a detection limit of 0.56 nM and a recovery rate of 96.2–104.1%, indicating that this fluorescence sensor can be used for the detection of thrombin content in human serum.

  3. A sensitive turn on fluorescent probe for detection of biothiols using MnO2@carbon dots nanocomposites

    Science.gov (United States)

    Garg, Dimple; Mehta, Akansha; Mishra, Amit; Basu, Soumen

    2018-03-01

    Presently, the combination of carbon quantum dots (CQDs) and metal oxide nanostructures in one frame are being considered for the sensing of purine compounds. In this work, a combined system of CQDs and MnO2 nanostructures was used for the detection of anticancer drugs, 6-Thioguanine (6-TG) and 6-Mercaptopurine (6-MP). The CQDs were synthesized through microwave synthesizer and the MnO2 nanostructures (nanoflowers and nanosheets) were synthesized using facile hydrothermal technique. The CQDs exhibited excellent fluorescence emission at 420 nm when excited at 320 nm wavelength. By combining CQDs and MnO2 nanostructures, quenching of fluorescence was observed which was attributed to fluorescence resonance energy transfer (FRET) mechanism, where CQDs act as electron donor and MnO2 act as acceptor. This fluorescence quenching behaviour disappeared on the addition of 6-TG and 6-MP due to the formation of Mn-S bond. The detection limit for 6-TG (0.015 μM) and 6-MP (0.014 μM) was achieved with the linear range of concentration (0-50 μM) using both MnO2 nanoflowers and nanosheets. Moreover, the as-prepared fluorescence-sensing technique was successfully employed for the detection of bio-thiol group in enapril drug. Thus a facile, cost-effective and benign chemistry approach for biomolecule detection was designed.

  4. A Dansyl-Rhodamine Based Fluorescent Probe for Detection of Hg2+ and Cu2.

    Science.gov (United States)

    Yuan, Shizhuang; Su, Wei; Wang, Enju

    2017-09-01

    A novel fluorescent probe based on dansyl-appended rhodamine B was developed. The probe can selectively recognize and sense Hg2+ and Cu2+ from other common metal ions by showing unique fluorescence and absorption characteristics. In MeCN/HEPES buffer solution, the probe gives a ratiometric fluorescent response to Hg2+, which was ascribed to the fluorescence resonance energy transfer from dansyl moiety to the ring-opened rhodamine B moiety, while the presence of Cu2+ causes fluorescence quenching. Beside the fluorescence change, the presence of Cu2+ and Hg2+ can induce intensive absorption at about 555 nm, which resulted in a color change from colorless to pink.

  5. Rapid Simultaneous Amplification and Detection of the MBR/JH Chromosomal Translocation by Fluorescence Melting Curve Analysis

    Science.gov (United States)

    Bohling, Sandra D.; King, Thomas C.; Wittwer, Carl T.; Elenitoba-Johnson, Kojo S. J.

    1999-01-01

    Polymerase chain reaction (PCR) amplification and product analysis for the detection of chromosomal translocations, such as the t(14;18), has traditionally been a two-step process. PCR product detection has generally entailed gel electrophoresis and/or hybridization or sequencing for confirmation of assay specificity. Using a microvolume fluorimeter integrated with a thermal cycler and a PCR-compatible double-stranded DNA (dsDNA) binding fluorescent dye (SYBR Green I), we investigated the feasibility of simultaneous thermal amplification and detection of MBR/JH translocation products by fluorescence melting curve analysis. We analyzed DNA from 30 cases of lymphoproliferative disorders comprising 19 cases of previously documented MBR/JH-positive follicle center lymphoma and 11 reactive lymphadenopathies. The samples were coded and analyzed blindly for the presence of MBR/JH translocations by fluorescence melting curve analysis. We also performed dilutional assays using the MBR/JH-positive cell line SUDHL-6. Multiplex PCR for MBR/JH and β-globin was used to simultaneously assess sample adequacy. All (100%) of the 19 cases previously determined to be MBR/JH positive by conventional PCR analysis showed a characteristic sharp decrease in fluorescence at ∼90°C by melting curve analysis after amplification. Fluorescence melting peaks obtained by plotting the negative derivative of fluorescence over temperature (−dF/dT) versus temperature (T) showed melting temperatures (Tm) at 88.85 ± 1.15°C. In addition, multiplex assays using both MBR/JH and β-globin primers yielded easily distinguishable fluorescence melting peaks at ∼90°C and 81.2°C, respectively. Dilutional assays revealed that fluorescence melting curve analysis was more sensitive than conventional PCR and agarose gel electrophoresis with ultraviolet transillumination by as much as 100-fold. Simultaneous amplification and fluorescence melting curve analysis is a simple, reliable, and sensitive method

  6. Detection of Bacteria by Fluorescence in Situ Hybridization in Culture-Negative Soft Tissue Filler Lesions

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Tolker-Nielsen, Tim; Givskov, Michael

    2009-01-01

    BACKGROUND Adverse reactions to polyacrylamide gel occur as swellings or nodules, and controversy exists whether these are due to bacterial infection or an autoimmune reaction to the filler. OBJECTIVES Biopsies from culture-negative long-lasting nodules after injection with different types...... of polyacrylamide gel were examined with a combination of Gram stain and fluorescence in situ hybridization. RESULTS Bacteria were detected in biopsies from seven of eight patients. They inhabited gel and intervening tissue and tended to lie in aggregates. CONCLUSION This study supports the assumption...... that infection with bacteria in aggregates causes culture-negative late adverse reactions to polyacrylamide gel, suggesting a biofilm environment. The authors have indicated no significant interest with commercial supporters....

  7. Structure and dynamics of olefin radical cation aggregates. Time-resolved fluorescence detected magnetic resonance

    International Nuclear Information System (INIS)

    Desrosiers, M.F.; Trifunac, A.D.

    1986-01-01

    The time-resolved EPR spectra and thus the structure and dynamics of transient hydrocarbon radical cations are obtained by the pulse radiolysis-fluorescence detected magnetic resonance (FDMR) technique. Here the authors report the observation of short-lived radical cations from olefins. FDMR-EPR spectra of radical cations from tetramethylethylene and cyclohexadiene are illustrated. The olefin radical cations, FDMR spectra are concentration-dependent, since dimerization with neutral molecules takes place at higher (>10 -2 M) olefin concentration. Rate constants for the dimerization reaction are derived and the effect of solvent viscosity on aggregate formation is demonstrated. By monitoring the further reactions of dimer cations the authors have obtained EPR evidence for previously unobserved higher-order (multimer) radical cation aggregates of olefins. 16 references, 5 figures

  8. Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Su, Hui [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, the author introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties of suitably designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, they demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm2 for 40-μm wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection. In the second part of this dissertation, the author used laser-induced native fluorescence coupled with capillary electrophoresis (LINF-CE) and microscope imaging to study the single cell degranulation. On the basis of good temporal correlation with events observed through an optical microscope, they have identified individual peaks in the fluorescence electropherograms as serotonin released from the granular core on contact with the surrounding fluid.

  9. Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Su, Hui [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, we introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties of suitably designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, we demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm2 for 40-μm wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection.

  10. Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

    International Nuclear Information System (INIS)

    Hui Su

    2001-01-01

    Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, we introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties of suitably designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, we demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm(sub 2) for 40-(micro)m wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection

  11. Detection of rhodopsin dimerization in situ by PIE-FCCS, a time-resolved fluorescence spectroscopy.

    Science.gov (United States)

    Smith, Adam W

    2015-01-01

    Rhodopsin self-associates in the plasma membrane. At low concentrations, the interactions are consistent with a monomer-dimer equilibrium (Comar et al., J Am Chem Soc 136(23):8342-8349, 2014). At high concentrations in native tissue, higher-order clusters have been observed (Fotiadis et al., Nature 421:127-128, 2003). The physiological role of rhodopsin dimerization is still being investigated, but it is clear that a quantitative assessment is essential to determining the function of rhodopsin clusters in vision. To quantify rhodopsin interactions, I will outline the theory and methodology of a specialized time-resolved fluorescence spectroscopy for measuring membrane protein-protein interactions called pulsed-interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS). The strength of this technique is its ability to quantify rhodopsin interactions in situ (i.e., a live cell plasma membrane). There are two reasons for restricting the scope to live cell membranes. First, the compositional heterogeneity of the plasma membrane creates a complex milieu with thousands of lipid, protein, and carbohydrate species. This makes it difficult to infer quaternary interactions from detergent solubilized samples or construct a model phospholipid bilayer that recapitulates all of the interactions present in native membranes. Second, organizational structure and dynamics is a key feature of the plasma membrane, and fixation techniques like formaldehyde cross-linking and vitrification will modulate the interactions. PIE-FCCS is based on two-color fluorescence imaging with time-correlated single-photon counting (TCSPC) (Becker et al., Rev Sci Instrum 70:1835-1841, 1999). By time-tagging every detected photon, the data can be analyzed as a fluorescence intensity distribution, fluorescence lifetime histogram, or fluorescence (cross-)correlation spectra (FCS/FCCS) (Becker, Advanced time-correlated single-photon counting techniques, Springer, Berlin, 2005). These

  12. Ratiometric Fluorescent Detection of Pb2+ by FRET-Based Phthalocyanine-Porphyrin Dyads.

    Science.gov (United States)

    Zhang, Dongli; Zhu, Mengliang; Zhao, Luyang; Zhang, Jinghui; Wang, Kang; Qi, Dongdong; Zhou, Yang; Bian, Yongzhong; Jiang, Jianzhuang

    2017-12-04

    Sensitive and selective detection of Pb 2+ is a very worthwhile endeavor in terms of both human health and environmental protection, as the heavy metal is fairly ubiquitous and highly toxic. In this study, we designed phthalocyanine-porphyrin (Pc-Por) heterodyads, namely, H 2 Pc-α-ZnPor (1) and H 2 Pc-β-ZnPor (2), by connecting a zinc(II) porphyrin moiety to the nonperipheral (α) or peripheral (β) position of a metal-free phthalocyanine moiety. Upon excitation at the porphyrin Soret region (420 nm), both of the dyads exhibited not only a porphyrin emission (605 nm) but also a phthalocyanine emission (ca. 700 nm), indicating the occurrence of intramolecular fluorescence resonance energy transfer (FRET) processes from the porphyrin donor to the phthalocyanine acceptor. The dyads can selectively bind Pb 2+ in the phthalocyanine core leading to a red shift of the phthalocyanine absorption and thus a decrease of spectral overlap between the porphyrin emission and phthalocyanine absorption, which in turn suppresses the intramolecular FRET. In addition, the binding of Pb 2+ can highly quench the emission of phthalocyanine by heavy-metal ion effects. The synergistic coupled functions endow the dyads with remarkable ratiometric fluorescent responses at two distinct wavelengths (F 605 /F 703 for 1 and F 605 /F 700 for 2). The emission intensity ratio increased as a linear function to the concentration of Pb 2+ in the range of 0-4.0 μM, whereas the detection limits were determined to be 3.4 × 10 -9 and 2.2 × 10 -8 M for 1 and 2, respectively. Furthermore, by comparative study of 1 and 2, the effects of distance and relative orientation between Pc and ZnPor fluorophores on the FRET efficiency and sensing performance were highlighted, which is helpful for further optimizing such FRET systems.

  13. Sensitivity and specificity of fluorescence microlymphography for detecting lymphedema of the lower extremity.

    Science.gov (United States)

    Keo, Hong H; Schilling, Marianne; Büchel, Roland; Gröchenig, Ernst; Engelberger, Rolf P; Willenberg, Torsten; Baumgartner, Iris; Gretener, Silvia B

    2013-06-01

    Fluorescence microlymphography (FML) is used to visualize the lymphatic capillaries. A maximum spread of the fluorescence dye of ≥ 12 mm has been suggested for the diagnosis of lymphedema. However, data on sensitivity and specificity are lacking. The aim of this study was to investigate the accuracy of FML for diagnosing lymphedema in patients with leg swelling. Patients with lower extremity swelling were clinically assessed and separated into lymphedema and non-lymphatic edema groups. FML was studied in all affected legs and the maximum spread of lymphatic capillaries was measured. Test accuracy and receiver operator characteristic (ROC) analysis was performed to assess possible threshold values that predict lymphedema. Between March 2008 and August 2011 a total of 171 patients (184 legs) with a median age of 43.5 (IQR 24, 54) years were assessed. Of those, 94 (51.1%) legs were diagnosed with lymphedema. The sensitivity, specificity, positive and negative likelihood ratio and positive and negative predictive value were 87%, 64%, 2.45, 0.20, 72% and 83% for the 12-mm cut-off level and 79%, 83%, 4.72, 0.26, 83% and 79% for the 14-mm cut-off level, respectively. The area under the ROC curve was 0.82 (95% CI: 0.76, 0.88). Sensitivity was higher in the secondary versus primary lymphedema (95.0% vs 74.3%, p = 0.045). No major adverse events were observed. In conclusion, FML is a simple and safe technique for detecting lymphedema in patients with leg swelling. A cut-off level of ≥ 14-mm maximum spread has a high sensitivity and high specificity of detecting lymphedema and should be chosen.

  14. A rapid and cost-effective fluorescence detection in tube (FDIT) method to analyze protein phosphorylation.

    Science.gov (United States)

    Jin, Xiao; Gou, Jin-Ying

    2016-01-01

    Protein phosphorylation is one of the most important post-translational modifications catalyzed by protein kinases in living organisms. The advance of genome sequencing provided the information of protein kinase families in many organisms, including both model and non-model plants. The development of proteomics technologies also enabled scientists to efficiently reveal a large number of protein phosphorylations of an organism. However, kinases and phosphorylation targets are still to be connected to illustrate the complicated network in life. Here we adapted Pro-Q ® Diamond (Pro-Q ® Diamond Phosphoprotein Gel Stain), a widely used phosphoprotein gel-staining fluorescence dye, to establish a rapid, economical and non-radioactive fluorescence detection in tube (FDIT) method to analyze phosphorylated proteins. Taking advantages of high sensitivity and specificity of Pro-Q ® diamond, the FDIT method is also demonstrated to be rapid and reliable, with a suitable linear range for in vitro protein phosphorylation. A significant and satisfactory protein kinase reaction was detected as fast as 15 min from Wheat Kinase START 1.1 (WKS1.1) on a thylakoid ascorbate peroxidase (tAPX), an established phosphorylation target in our earlier study. The FDIT method saves up to 95% of the dye consumed in a gel staining method. The FDIT method is remarkably quick, highly reproducible, unambiguous and capable to be scaled up to dozens of samples. The FDIT method could serve as a simple and sensitive alternative procedure to determine protein kinase reactions with zero radiation exposure, as a supplementation to other widely used radioactive and in-gel assays.

  15. A rapid and cost-effective fluorescence detection in tube (FDIT method to analyze protein phosphorylation

    Directory of Open Access Journals (Sweden)

    Xiao Jin

    2016-11-01

    Full Text Available Abstract Background Protein phosphorylation is one of the most important post-translational modifications catalyzed by protein kinases in living organisms. The advance of genome sequencing provided the information of protein kinase families in many organisms, including both model and non-model plants. The development of proteomics technologies also enabled scientists to efficiently reveal a large number of protein phosphorylations of an organism. However, kinases and phosphorylation targets are still to be connected to illustrate the complicated network in life. Results Here we adapted Pro-Q® Diamond (Pro-Q® Diamond Phosphoprotein Gel Stain, a widely used phosphoprotein gel-staining fluorescence dye, to establish a rapid, economical and non-radioactive fluorescence detection in tube (FDIT method to analyze phosphorylated proteins. Taking advantages of high sensitivity and specificity of Pro-Q® diamond, the FDIT method is also demonstrated to be rapid and reliable, with a suitable linear range for in vitro protein phosphorylation. A significant and satisfactory protein kinase reaction was detected as fast as 15 min from Wheat Kinase START 1.1 (WKS1.1 on a thylakoid ascorbate peroxidase (tAPX, an established phosphorylation target in our earlier study. Conclusion The FDIT method saves up to 95% of the dye consumed in a gel staining method. The FDIT method is remarkably quick, highly reproducible, unambiguous and capable to be scaled up to dozens of samples. The FDIT method could serve as a simple and sensitive alternative procedure to determine protein kinase reactions with zero radiation exposure, as a supplementation to other widely used radioactive and in-gel assays.

  16. Non-Covalent Fluorescent Labeling of Hairpin DNA Probe Coupled with Hybridization Chain Reaction for Sensitive DNA Detection.

    Science.gov (United States)

    Song, Luna; Zhang, Yonghua; Li, Junling; Gao, Qiang; Qi, Honglan; Zhang, Chengxiao

    2016-04-01

    An enzyme-free signal amplification-based assay for DNA detection was developed using fluo