The Experts below are selected from a list of 17622 Experts worldwide ranked by ideXlab platform

Joseph R. Lakowicz - One of the best experts on this subject based on the ideXlab platform.

  • enhanced forster resonance energy transfer fret on single metal particle
    Journal of Physical Chemistry C, 2007
    Co-Authors: Jian Zhang, Yi Fu, Joseph R. Lakowicz
    Abstract:

    We examined the effect of a Metallic Silver particle on Forster resonance energy transfer (FRET) between a nearby donor-acceptor pair. A donor- labeled oligonucleotide was chemically bound to a single Silver particle and then an acceptor- labeled complementary oligonucleotide was conjugated by hybridization. The photophysical behavior of FRET between the donor-acceptor pair on the metal particle was investigated using both ensemble emission spectra and single- molecule fluorescence detections. Both the emission intensities and lifetimes indicated an enhanced FRET efficiency due to the metal particle. This interaction led to an increase in the Forster distance for energy transfer from 8.3 to 13 nm. The rate constant of FRET near the Silver particle was 21-fold faster than that of unbound donor-acceptor pair. These results suggest the use of metal-enhanced FRET for measuring proximity of large biomolecules or for energy transfer based assays.

  • effects of Metallic Silver island films on resonance energy transfer between n n dipropyl tetramethyl indocarbocyanine cy3 and n n dipropyl tetramethyl indodicarbocyanine cy5 labeled dna
    Biopolymers, 2003
    Co-Authors: Joanna Malicka, Ignacy Gryczynski, Jozef Kusba, Joseph R. Lakowicz
    Abstract:

    Resonance energy transfer (RET) is typically limited to distances below 60 A, which can be too short for some biomedical assays. We examined a new method for increasing the RET distances by placing donor- and acceptor-labeled DNA oligomers between two slides coated with Metallic Silver particles. A N,N'-(dipropyl)-tetramethylindocarbocyanine donor and a N,N'-(dipropyl)-tetramethylindodicarbocyanine acceptor were covalently bound to opposite 5' ends of complementary 23 base pair DNA oligomers. The transfer efficiency was 25% in the absence of Silver particles or if only one slide was Silvered, and it increased to an average value near 64% between two Silvered slides. The average value of the Forster distance increased from 58 to 77 A. The energy transfer data were analyzed with a model assuming two populations of donor-acceptor pairs: unaffected and affected by Silver island films. In an affected fraction of about 28%, the apparent energy transfer efficiency is near 87% and the Forster distance increases to 119 A. These results suggest the use of Metallic Silver particles to increase the distances over which RET occurs in biomedical and biotechnology assays.

  • enhanced emission of highly labeled dna oligomers near Silver Metallic surfaces
    Analytical Chemistry, 2003
    Co-Authors: Joanna Malicka, Ignacy Gryczynski, Joseph R. Lakowicz
    Abstract:

    Fluorescein is a widely used fluorescent probe in DNA analysis. One difficulty with fluorescein is its self-quenching due to resonance energy transfer between the residues, which results in decreased intensities with increasing labeling density. We examined the emission spectral properties of DNA oligomers labeled with one or five fluorescein residues. The emission intensity of the more highly labeled oligomer was decreased due to self-quenching. The self-quenching was mostly eliminated when this oligomer was held ∼90 A from the surface of Metallic Silver particles. The intensities increased 7- and 19-fold for the oligomers with one or five fluoresceins, respectively. The increased intensity did not result in increased photobleaching. These results suggest the use of substrates coated with Silver particles for increased sensitivity on DNA arrays or for DNA analysis.

  • effects of Metallic Silver particles on the emission properties of ru bpy 3 2
    Chemical Physics Letters, 2003
    Co-Authors: Ignacy Gryczynski, Joanna Malicka, Elisabeth Holde, Nicolas Dicesare, Joseph R. Lakowicz
    Abstract:

    We examined the emission spectral properties of [Ru(bpy)3]2+ in a thin film of polyvinyl alcohol coated on quartz slides or on Metallic Silver particles. The relative intensities were several fold higher on the surface containing Silver particles, and the decay times were several fold smaller. These results are consistent with an approximate 20-fold increase in the radiative decay rate of [Ru(bpy)3]2+ when near Metallic Silver particles. These results suggest the use of Silver particles for increased detectability of the emission from transition metal–ligand complexes.

  • increased resonance energy transfer between fluorophores bound to dna in proximity to Metallic Silver particles
    Analytical Biochemistry, 2003
    Co-Authors: Joanna Malicka, Ignacy Gryczynski, Jozef Kusba, Jiyu Fang, Joseph R. Lakowicz
    Abstract:

    We examined the effects of Metallic Silver particles on resonance energy transfer (RET) between fluorophores covalently bound to DNA. A coumarin donor and a Cy3 acceptor were positioned at opposite ends of a 23-bp double helical DNA oligomer. In the absence of Silver particles the extent of RET is near 9%, consistent with a Forster distance R0 near 50 A and a donor to acceptor distance near 75 A. The transfer efficiency increased when the solution of AMCA-DNA-Cy3 was placed between two quartz plates coated with Silver island films to near 64%, as determined by both steady-state and time-resolved measurements. The apparent R0 in the presence of Silver island films increases to about 110 A. These values of the transfer efficiency and R0 represent weighted averages for donor-acceptor pairs near and distant from the Metallic surfaces, so that the values at an optimal distance are likely to be larger. The increased energy transfer is observed only between two sandwiched Silvered slides. When we replaced one Silvered slide with a quartz plate the effect vanished. Also, the increased energy transfer was not observed for Silvered slides separated more than a few micrometers. These results suggest the use of metal-enhanced RET in PCR, hybridization, and other DNA assays, and the possibility of controlling energy transfer by the distance between Silver surfaces.

Yihang Guo - One of the best experts on this subject based on the ideXlab platform.

  • one pot solvothermal preparation and enhanced photocatalytic activity of Metallic Silver and graphene co doped bivo4 ternary systems
    Applied Surface Science, 2015
    Co-Authors: Yongge Wei, Yihang Guo, Wa Guo, Yingna Guo
    Abstract:

    Abstract A series of Metallic Silver and graphene (GR) co-doped monoclinic BiVO 4 ternary systems (Ag/GR/BiVO 4 ) are demonstrated by a single-step solvothermal method. The phase and chemical structure, morphology, textural and optical absorption properties of the Ag/GR/BiVO 4 ternary systems are well characterized, and then their simulated sunlight and visible-light photocatalytic activity were evaluated by the degradation of a typical dye pollutant, rhodamine B (RhB). For comparison, binary systems of Ag/BiVO 4 and GR/BiVO 4 as well as solitary BiVO 4 are also tested under the same conditions. Meanwhile, the separation and transportation of the photogenerated carriers in the simulated sunlight-irradiating Ag/GR/BiVO 4 ternary systems are studied by photoelectrochemistry experiments, and the active species generated during the process of photodegradation are investigated by free radical and hole scavenging experiments. On the basis of the above results, mechanism of photocatalytic degradation of RhB over the Ag/GR/BiVO 4 ternary system is revealed. Finally, the reusability of the catalyst was evaluated by five consecutive catalytic runs.

  • photocatalytic degradation of an aqueous sulfamethoxazole over the Metallic Silver and keggin unit codoped titania nanocomposites
    Applied Surface Science, 2012
    Co-Authors: Geriletu Wang, Yahui Zhao, Yihang Guo, Xia Yang
    Abstract:

    Abstract A series of Metallic Silver and Keggin unit codoped titania nanocomposites (H 3 PW 12 O 40 /Ag–TiO 2 ) were prepared through a single step sol–gel-hydrothermal method. The composites mainly exhibited an anatase phase, featuring micro–meso dual porosity with Metallic Ag nanoparticles homogeneously dispersed on the surface of the H 3 PW 12 O 40 /Ag–TiO 2 ; meanwhile, they showed photoresponses to both the UV- and visible-light regions. As the novel composite photocatalysts, the materials were used to degrade a light-insensitive target compound, sulfamethoxazole (SMZ), under Xe lamp irradiation (320 nm  λ 3 PW 12 O 40 /Ag–TiO 2 were studied; additionally, the photocatalytic degradation pathway of an aqueous SMZ over H 3 PW 12 O 40 /Ag–TiO 2 was proposed by analyzing the reaction intermediates and final products identified during the photcatalytic process. Finally, the recyclability of the photocatalyst was evaluated.

  • mixed phase titania nanocomposite codoped with Metallic Silver and vanadium oxide new efficient photocatalyst for dye degradation
    Journal of Hazardous Materials, 2010
    Co-Authors: Xia Yang, Yingna Guo, Mingxi Huo, Yihang Guo
    Abstract:

    Abstract Titania nanocomposite codoped with Metallic Silver and vanadium oxide was prepared by a one-step sol–gel–solvothermal method in the presence of a triblock copolymer surfactant (P123). The resulting Ag/V–TiO 2 three-component junction system exhibited an anatase/rutile (weight ratio of 73.8:26.2) mixed phase structure, narrower band gap (2.25 eV), and extremely small particle sizes (ca. 12 nm) with Metallic Ag particles well distributed on the surface of the composite. The Ag/V–TiO 2 nanocomposite was used as the visible- and UV-light-driven photocatalyst to degrade dyes rhodamine B (RB) and coomassie brilliant blue G-250 (CBB) in an aqueous solution. At 1.8% Ag and 4.9% V doping, the Ag/V–TiO 2 system exhibited the highest visible- as well as UV-light photocatalytic activity; additionally, the activity of the three-component system exceeded that of Degussa P25, pure TiO 2 , single-doped TiO 2 system (Ag/TiO 2 or V–TiO 2 ) as well as P123-free-Ag/V–TiO 2 codoped system. The reasons for this enhanced photocatalytic activity were revealed.

Yingna Guo - One of the best experts on this subject based on the ideXlab platform.

  • one pot solvothermal preparation and enhanced photocatalytic activity of Metallic Silver and graphene co doped bivo4 ternary systems
    Applied Surface Science, 2015
    Co-Authors: Yongge Wei, Yihang Guo, Wa Guo, Yingna Guo
    Abstract:

    Abstract A series of Metallic Silver and graphene (GR) co-doped monoclinic BiVO 4 ternary systems (Ag/GR/BiVO 4 ) are demonstrated by a single-step solvothermal method. The phase and chemical structure, morphology, textural and optical absorption properties of the Ag/GR/BiVO 4 ternary systems are well characterized, and then their simulated sunlight and visible-light photocatalytic activity were evaluated by the degradation of a typical dye pollutant, rhodamine B (RhB). For comparison, binary systems of Ag/BiVO 4 and GR/BiVO 4 as well as solitary BiVO 4 are also tested under the same conditions. Meanwhile, the separation and transportation of the photogenerated carriers in the simulated sunlight-irradiating Ag/GR/BiVO 4 ternary systems are studied by photoelectrochemistry experiments, and the active species generated during the process of photodegradation are investigated by free radical and hole scavenging experiments. On the basis of the above results, mechanism of photocatalytic degradation of RhB over the Ag/GR/BiVO 4 ternary system is revealed. Finally, the reusability of the catalyst was evaluated by five consecutive catalytic runs.

  • mixed phase titania nanocomposite codoped with Metallic Silver and vanadium oxide new efficient photocatalyst for dye degradation
    Journal of Hazardous Materials, 2010
    Co-Authors: Xia Yang, Yingna Guo, Mingxi Huo, Yihang Guo
    Abstract:

    Abstract Titania nanocomposite codoped with Metallic Silver and vanadium oxide was prepared by a one-step sol–gel–solvothermal method in the presence of a triblock copolymer surfactant (P123). The resulting Ag/V–TiO 2 three-component junction system exhibited an anatase/rutile (weight ratio of 73.8:26.2) mixed phase structure, narrower band gap (2.25 eV), and extremely small particle sizes (ca. 12 nm) with Metallic Ag particles well distributed on the surface of the composite. The Ag/V–TiO 2 nanocomposite was used as the visible- and UV-light-driven photocatalyst to degrade dyes rhodamine B (RB) and coomassie brilliant blue G-250 (CBB) in an aqueous solution. At 1.8% Ag and 4.9% V doping, the Ag/V–TiO 2 system exhibited the highest visible- as well as UV-light photocatalytic activity; additionally, the activity of the three-component system exceeded that of Degussa P25, pure TiO 2 , single-doped TiO 2 system (Ag/TiO 2 or V–TiO 2 ) as well as P123-free-Ag/V–TiO 2 codoped system. The reasons for this enhanced photocatalytic activity were revealed.

Xia Yang - One of the best experts on this subject based on the ideXlab platform.

  • large scale ultra adhesive and mechanically flexible Silver grids transparent electrodes by solution process
    Organic Electronics, 2018
    Co-Authors: Qingxia Wang, Xia Yang, Xiaotian Hu, Xiangchuan Meng, Yingbo Xiao, Yiwang Chen
    Abstract:

    Abstract Metal grids have great potential in flexible transparent electrodes (FTEs) due to the high transmittance and conductivity. In addition, mechanical characteristic and adhesion are also crucial issues for commercial application. Here ultra-adhesive and mechanically robust metal grids FTEs were fabricated by in-situ growth Metallic Silver (s-Ag) film on polydopamine (PDA) adhesive-aid poly(ethylene terephthalate) (PET) substrate and electrospun polyacrylonitrile (PAN) fibers mask assisted acid etching, consequently generating s-Ag grids@PDA/PET. Transfer-free Silver grids mainly offer high conductivity whereas the powerfully adhesive PDA can supply the mechanical flexibility. The s-Ag grids@PDA/PET possesses superior mechanical robustness and maintains high conductivity under harsh conditions. Further, the brightness of light-emitting diode (LED) connected the large-scale (3 × 3 cm2) s-Ag grids@PDA/PET is stable under continuously mechanical attack. A power conversion efficiency of 6.4% has been achieved for s-Ag grids@PDA/PET used as an anode in polymer solar cells with 1.01 cm2 effective area, which is comparable to the commercialized ITO/PET electrode. These results show that s-Ag grids@PDA/PET can improve the adhesion and mechanical property of conventional metal electrode.

  • photocatalytic degradation of an aqueous sulfamethoxazole over the Metallic Silver and keggin unit codoped titania nanocomposites
    Applied Surface Science, 2012
    Co-Authors: Geriletu Wang, Yahui Zhao, Yihang Guo, Xia Yang
    Abstract:

    Abstract A series of Metallic Silver and Keggin unit codoped titania nanocomposites (H 3 PW 12 O 40 /Ag–TiO 2 ) were prepared through a single step sol–gel-hydrothermal method. The composites mainly exhibited an anatase phase, featuring micro–meso dual porosity with Metallic Ag nanoparticles homogeneously dispersed on the surface of the H 3 PW 12 O 40 /Ag–TiO 2 ; meanwhile, they showed photoresponses to both the UV- and visible-light regions. As the novel composite photocatalysts, the materials were used to degrade a light-insensitive target compound, sulfamethoxazole (SMZ), under Xe lamp irradiation (320 nm  λ 3 PW 12 O 40 /Ag–TiO 2 were studied; additionally, the photocatalytic degradation pathway of an aqueous SMZ over H 3 PW 12 O 40 /Ag–TiO 2 was proposed by analyzing the reaction intermediates and final products identified during the photcatalytic process. Finally, the recyclability of the photocatalyst was evaluated.

  • mixed phase titania nanocomposite codoped with Metallic Silver and vanadium oxide new efficient photocatalyst for dye degradation
    Journal of Hazardous Materials, 2010
    Co-Authors: Xia Yang, Yingna Guo, Mingxi Huo, Yihang Guo
    Abstract:

    Abstract Titania nanocomposite codoped with Metallic Silver and vanadium oxide was prepared by a one-step sol–gel–solvothermal method in the presence of a triblock copolymer surfactant (P123). The resulting Ag/V–TiO 2 three-component junction system exhibited an anatase/rutile (weight ratio of 73.8:26.2) mixed phase structure, narrower band gap (2.25 eV), and extremely small particle sizes (ca. 12 nm) with Metallic Ag particles well distributed on the surface of the composite. The Ag/V–TiO 2 nanocomposite was used as the visible- and UV-light-driven photocatalyst to degrade dyes rhodamine B (RB) and coomassie brilliant blue G-250 (CBB) in an aqueous solution. At 1.8% Ag and 4.9% V doping, the Ag/V–TiO 2 system exhibited the highest visible- as well as UV-light photocatalytic activity; additionally, the activity of the three-component system exceeded that of Degussa P25, pure TiO 2 , single-doped TiO 2 system (Ag/TiO 2 or V–TiO 2 ) as well as P123-free-Ag/V–TiO 2 codoped system. The reasons for this enhanced photocatalytic activity were revealed.

Joanna Malicka - One of the best experts on this subject based on the ideXlab platform.

  • effects of Metallic Silver island films on resonance energy transfer between n n dipropyl tetramethyl indocarbocyanine cy3 and n n dipropyl tetramethyl indodicarbocyanine cy5 labeled dna
    Biopolymers, 2003
    Co-Authors: Joanna Malicka, Ignacy Gryczynski, Jozef Kusba, Joseph R. Lakowicz
    Abstract:

    Resonance energy transfer (RET) is typically limited to distances below 60 A, which can be too short for some biomedical assays. We examined a new method for increasing the RET distances by placing donor- and acceptor-labeled DNA oligomers between two slides coated with Metallic Silver particles. A N,N'-(dipropyl)-tetramethylindocarbocyanine donor and a N,N'-(dipropyl)-tetramethylindodicarbocyanine acceptor were covalently bound to opposite 5' ends of complementary 23 base pair DNA oligomers. The transfer efficiency was 25% in the absence of Silver particles or if only one slide was Silvered, and it increased to an average value near 64% between two Silvered slides. The average value of the Forster distance increased from 58 to 77 A. The energy transfer data were analyzed with a model assuming two populations of donor-acceptor pairs: unaffected and affected by Silver island films. In an affected fraction of about 28%, the apparent energy transfer efficiency is near 87% and the Forster distance increases to 119 A. These results suggest the use of Metallic Silver particles to increase the distances over which RET occurs in biomedical and biotechnology assays.

  • enhanced emission of highly labeled dna oligomers near Silver Metallic surfaces
    Analytical Chemistry, 2003
    Co-Authors: Joanna Malicka, Ignacy Gryczynski, Joseph R. Lakowicz
    Abstract:

    Fluorescein is a widely used fluorescent probe in DNA analysis. One difficulty with fluorescein is its self-quenching due to resonance energy transfer between the residues, which results in decreased intensities with increasing labeling density. We examined the emission spectral properties of DNA oligomers labeled with one or five fluorescein residues. The emission intensity of the more highly labeled oligomer was decreased due to self-quenching. The self-quenching was mostly eliminated when this oligomer was held ∼90 A from the surface of Metallic Silver particles. The intensities increased 7- and 19-fold for the oligomers with one or five fluoresceins, respectively. The increased intensity did not result in increased photobleaching. These results suggest the use of substrates coated with Silver particles for increased sensitivity on DNA arrays or for DNA analysis.

  • effects of Metallic Silver particles on the emission properties of ru bpy 3 2
    Chemical Physics Letters, 2003
    Co-Authors: Ignacy Gryczynski, Joanna Malicka, Elisabeth Holde, Nicolas Dicesare, Joseph R. Lakowicz
    Abstract:

    We examined the emission spectral properties of [Ru(bpy)3]2+ in a thin film of polyvinyl alcohol coated on quartz slides or on Metallic Silver particles. The relative intensities were several fold higher on the surface containing Silver particles, and the decay times were several fold smaller. These results are consistent with an approximate 20-fold increase in the radiative decay rate of [Ru(bpy)3]2+ when near Metallic Silver particles. These results suggest the use of Silver particles for increased detectability of the emission from transition metal–ligand complexes.

  • increased resonance energy transfer between fluorophores bound to dna in proximity to Metallic Silver particles
    Analytical Biochemistry, 2003
    Co-Authors: Joanna Malicka, Ignacy Gryczynski, Jozef Kusba, Jiyu Fang, Joseph R. Lakowicz
    Abstract:

    We examined the effects of Metallic Silver particles on resonance energy transfer (RET) between fluorophores covalently bound to DNA. A coumarin donor and a Cy3 acceptor were positioned at opposite ends of a 23-bp double helical DNA oligomer. In the absence of Silver particles the extent of RET is near 9%, consistent with a Forster distance R0 near 50 A and a donor to acceptor distance near 75 A. The transfer efficiency increased when the solution of AMCA-DNA-Cy3 was placed between two quartz plates coated with Silver island films to near 64%, as determined by both steady-state and time-resolved measurements. The apparent R0 in the presence of Silver island films increases to about 110 A. These values of the transfer efficiency and R0 represent weighted averages for donor-acceptor pairs near and distant from the Metallic surfaces, so that the values at an optimal distance are likely to be larger. The increased energy transfer is observed only between two sandwiched Silvered slides. When we replaced one Silvered slide with a quartz plate the effect vanished. Also, the increased energy transfer was not observed for Silvered slides separated more than a few micrometers. These results suggest the use of metal-enhanced RET in PCR, hybridization, and other DNA assays, and the possibility of controlling energy transfer by the distance between Silver surfaces.

  • effects of Metallic Silver particles on resonance energy transfer between fluorophores bound to dna
    Journal of Fluorescence, 2003
    Co-Authors: Joseph R. Lakowicz, Joanna Malicka, Jozef Kuśba, Yibing She, Sabato Dauria, Zygmu Gryczynski, Ignacy Gryczynski
    Abstract:

    We examined the effects of Metallic Silver island films on resonance energy transfer (RET) between a donor and acceptor bound to double helical DNA. The donor was 48,6-diamidino-2-phenylindole (DAPI) and the acceptor was propidium iodide (PI). Proximity of the labeled DNA to the Silver particles resulted in a dramatic increase in RET as seen from the emission spectra and the donor