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"Timing gate"

Xiao-Yu Wang, Cheng-Gang Niu, Li-Juan Guo, Liu-Yin Hu, Sheng-Quan Wu, Guang-Ming Zeng, Fei Li
This paper describes a label-free 17E DNAzyme-based time-gated fluorescence sensor for Pb(2+) detection by unmodified gold nanoparticles (GNPs) and a terbium ternary complex. The fluorophore that used in this paper is a terbium ternary complex. Its signal can be measured in a time-gated manner which could eliminate most of the unspecific fluorescent background. It is well known that unfolded single-stranded DNA (ssDNA) could be adsorbed on GNPs while double-stranded DNA could not. The cleavage of the substrate by the 17E DNAzyme in the presence of Pb(2+) causes the release of ssDNA from the 17E-17S duplex to be absorbed onto GNPs, preventing the aggregation of GNPs and then leading to a fluorescence decrease of terbium ternary complex...
December 1, 2016: Journal of Fluorescence
Orel Shlomi, Eyal Preter, Dexin Ba, Yosef London, Yair Antman, Avi Zadok
Brillouin optical correlation-domain analysis (B-OCDA) allows for distributed measurements of strain and temperature with sub-cm resolution. Time-multiplexing techniques have previously extended B-OCDA to the monitoring of many km of fiber and two million resolution points. Thus far, however, the number of scans of correlation peaks positions, necessary to cover the fiber under test, was restricted to the order of 100 or more. In this work we report a B-OCDA protocol that is able to address an entire fiber using only 11 pairs of position scans per choice of frequency...
November 14, 2016: Optics Express
Amaury Badon, Dayan Li, Geoffroy Lerosey, A Claude Boccara, Mathias Fink, Alexandre Aubry
Multiple scattering of waves in disordered media is a nightmare whether it is for detection or imaging purposes. So far, the best approach to get rid of multiple scattering is optical coherence tomography. This basically combines confocal microscopy and coherence time gating to discriminate ballistic photons from a predominant multiple scattering background. Nevertheless, the imaging-depth range remains limited to 1 mm at best in human soft tissues because of aberrations and multiple scattering. We propose a matrix approach of optical imaging to push back this fundamental limit...
November 2016: Science Advances
A Kaldun, A Blättermann, V Stooß, S Donsa, H Wei, R Pazourek, S Nagele, C Ott, C D Lin, J Burgdörfer, T Pfeifer
Although the time-dependent buildup of asymmetric Fano line shapes in absorption spectra has been of great theoretical interest in the past decade, experimental verification of the predictions has been elusive. Here, we report the experimental observation of the emergence of a Fano resonance in the prototype system of helium by interrupting the autoionization process of a correlated two-electron excited state with a strong laser field. The tunable temporal gate between excitation and termination of the resonance allows us to follow the formation of a Fano line shape in time...
November 11, 2016: Science
Andrew T Frawley, Robert Pal, David Parker
Chiral image contrast is demonstrated using enantiopure Eu(iii) complexes that emit right or left-handed circularly polarised light of opposite sign, at selected wavelengths.
October 27, 2016: Chemical Communications: Chem Comm
Chrystelle Neaime, Maria Amela-Cortes, Fabien Grasset, Yann Molard, Stéphane Cordier, Benjamin Dierre, Michel Mortier, Toshiaki Takei, Kohsei Takahashi, Hajime Haneda, Marc Verelst, Séverine Lechevallier
Bioimaging and cell labeling using red or near infrared phosphors emitting in the "therapeutic window" of biological tissues have recently become some of the most active research fields in modern medical diagnostics. However, because organic and inorganic autofluorophores are omnipresent in nature, very often the background signal from fluorochromes other than targeted probes has to be eliminated. This discrimination could be available using a time-gated luminescence microscopy (TGLM) technique associated with long lifetime phosphorescent nanocomposites...
October 25, 2016: Physical Chemistry Chemical Physics: PCCP
Gregory Roe, Joshua Darrall-Jones, Christopher Black, William Shaw, Kevin Till, Ben Jones
PURPOSE: The purpose of this study was to investigate the validity of timing gates and 10 Hz GPS units (Catapult Optimeye S5) against a criterion measure (50 Hz radar gun) for assessing maximum sprint velocity (Vmax). METHODS: Nine male professional rugby union players performed three maximal 40 m sprints with three minutes rest between each effort with Vmax assessed simultaneously via timing gates, 10 Hz GPSOpen (Openfield software), GPSSprint (Sprint software) and radar gun...
October 13, 2016: International Journal of Sports Physiology and Performance
Yao Yao, Chen Kong, Liang Yin, Atul D Jain, Kiira Ratia, Gregory R Thatcher, Terry W Moore, Tom Driver, Lawrence W Miller
Herein, we report the design, synthesis and characterization of a lanthanide(III) complex-based probe for the time-gated luminescence detection of hydrogen sulfide (H₂S) in aqueous media. The probe's unique sensing mechanism relies on the selective reduction of azide to amine by sulfide, followed by intramolecular cyclization to form a quinolinone. The quinolinone is a sensitizer that absorbs near-UV light and transfers excitation energy to coordinated Tb(III) or Eu(III) ions to trigger a strong "turn-on" luminescence response with ms-scale lifetimes characteristic of lanthanide complexes...
October 12, 2016: Chemistry: a European Journal
Blanca Del Rosal, Dirk H Ortgies, Nuria Fernández, Francisco Sanz-Rodríguez, Daniel Jaque, Emma Martín Rodríguez
The always present and undesired contribution of autofluorescence is here completely avoided by combining a simple time gating technology with long lifetime neodymium doped infrared-emitting nanoparticles.
October 6, 2016: Advanced Materials
Ali Mohamadi, Lawrence W Miller
The synthesis, photophysical properties, and kinetic stability of a series of water-soluble, highly emissive Tb(III) and Eu(III) complexes featuring triethylenetetraamine hexaacetic acid (TTHA) and cyclohexyl triethylenetetraamine hexaacetic acid (cyTTHA) chelator scaffolds and carbostyril sensitizers are reported. The unique and modular design of the chelators gives rise to striking quantum yields of emission in aqueous solutions (up to 54%) as well as the characteristic lanthanides' photophysical properties (long excited-state lifetimes, large effective Stokes shifts, and narrow emission peaks)...
October 3, 2016: Bioconjugate Chemistry
Erin Finley, Angelica Cobb, Anna Duke, Andrew Paterson, Jakoah Brgoch
Inorganic persistent luminescent phosphors are an excellent class of optical reporters for enabling sensitive point-of-care diagnostics, particularly with smartphone-based biosensing devices in testing formats such as the lateral flow assay (LFA). Here, the development of persistent phosphors for this application is focused on the solid solution (Sr1-δBaδ)2MgSi2O7:Eu(2+),Dy(3+) (δ = 0, 0.125, 0.25, 0.375), which is prepared using a high-temperature solid-state reaction as confirmed by synchrotron X-ray powder diffraction...
October 12, 2016: ACS Applied Materials & Interfaces
Alina Theisen, Bin Yan, Jeffery M Brown, Michael Morris, Bruno Bellina, Perdita E Barran
We demonstrate the capabilities of a laser-coupled ion mobility mass spectrometer for analysis of peptide sequence and structure showing ultraviolet photodissociation (UVPD) spectra of mass and mobility selected ions. A Synapt G2-S mass spectrometer has been modified to allow photointeraction of ions post the mobility cell. For this work, we have employed a single wavelength laser, which irradiates at 266 nm. We present the unique capabilities of this instrument and demonstrate several key features. Irradiation of luteinizing hormone releasing hormone (LHRH), growth hormone releasing hexapeptide (GHRP-6), and TrpCage (sequence NLYIQWLKDGGPSSGRPPPS) yields extensive b- and y-type fragmentation as well as a- and c-type ions...
October 3, 2016: Analytical Chemistry
Albert Redo-Sanchez, Barmak Heshmat, Alireza Aghasi, Salman Naqvi, Mingjie Zhang, Justin Romberg, Ramesh Raskar
Spatial resolution, spectral contrast and occlusion are three major bottlenecks for non-invasive inspection of complex samples with current imaging technologies. We exploit the sub-picosecond time resolution along with spectral resolution provided by terahertz time-domain spectroscopy to computationally extract occluding content from layers whose thicknesses are wavelength comparable. The method uses the statistics of the reflected terahertz electric field at subwavelength gaps to lock into each layer position and then uses a time-gated spectral kurtosis to tune to highest spectral contrast of the content on that specific layer...
2016: Nature Communications
Nima Sayyadi, Irene Justiniano, Russell E Connally, Run Zhang, Bingyang Shi, Liisa Kautto, Arun V Everest-Dass, Jingli Yuan, Bradley J Walsh, Dayong Jin, Robert D Willows, James A Piper, Nicolle H Packer
We describe the application of a synthetically developed tetradentate β-diketonate-europium chelate with high quantum yield (39%), for sensitive immunodetection of prostate cancer cells (DU145). MIL38 antibody, a mouse monoclonal antibody against Glypican 1, conjugated directly to the chelate via lysine residues, resulted in soluble (hydrophilic) and stable immunoconjugates. Indirect labeling of the antibody by a europium chelated secondary polyclonal antibody and a streptavidin/biotin pair was also performed...
October 4, 2016: Analytical Chemistry
Petr Fomin, Dmitry Zhelondz, Christian Kargel
For the production of high-quality parts from recycled plastics, a very high purity of the plastic waste to be recycled is mandatory. The incorporation of fluorescent tracers ("markers") into plastics during the manufacturing process helps overcome typical problems of non-tracer based optical classification methods. Despite the unique emission spectra of fluorescent markers, the classification becomes difficult when the host plastics exhibit (strong) autofluorescence that spectrally overlaps the marker fluorescence...
August 29, 2016: Applied Spectroscopy
Nathan R Gemmell, Aongus McCarthy, Michele M Kim, Israel Veilleux, Timothy C Zhu, Gerald S Buller, Brian C Wilson, Robert H Hadfield
This paper presents a novel compact fiberoptic based singlet oxygen near-infrared luminescence probe coupled to an InGaAs/InP single photon avalanche diode (SPAD) detector. Patterned time gating of the single-photon detector is used to limit unwanted dark counts and eliminate the strong photosensitizer luminescence background. Singlet oxygen luminescence detection at 1270 nm is confirmed through spectral filtering and lifetime fitting for Rose Bengal in water, and Photofrin in methanol as model photosensitizers...
July 25, 2016: Journal of Biophotonics
Xiangyou Liu, Gary B Braun, Haizheng Zhong, David J Hall, Wenlong Han, Mingde Qin, Chuanzhen Zhao, Meina Wang, Zhi-Gang She, Chuanbao Cao, Michael J Sailor, William B Stallcup, Erkki Ruoslahti, Kazuki N Sugahara
The rapid development of fluorescence imaging technologies requires concurrent improvements in the performance of fluorescent probes. Quantum dots have been extensively used as an imaging probe in various research areas because of their inherent advantages based on unique optical and electronic properties. However, their clinical translation has been limited by the potential toxicity especially from cadmium. Here, a versatile bioimaging probe is developed by using highly luminescent cadmium-free CuInSe2/ZnS core/shell quantum dots conjugated with CGKRK (Cys-Gly-Lys-Arg-Lys) tumor-targeting peptides...
January 13, 2016: Advanced Functional Materials
Mir Irfanullah, Navneet Bhardwaj, Arindam Chowdhury
Water dispersible citrate-capped LaF3:Eu(5%) nanocrystals (NCs) have been partially surface-functionalized by 1,10-phenanthroline (phen) via a ligand exchange method to produce novel water dispersed citrate/phen-capped LaF3:Eu(5%) NCs in which citrate ligands preserve the water dispersibility of the NCs and phen ligands act as sensitizers of surface Eu(3+)-dopant sites. The partial ligand exchange and the formation of water dispersed NCs have been monitored by (1)H NMR spectroscopy, as well as luminescence measurements at different time intervals during the reaction...
August 2, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Shujuan Liu, Yangliu Zhang, Hua Liang, Zejing Chen, Ziyu Liu, Qiang Zhao
Time-resolved luminescence imaging of intracellular oxygen levels has been demonstrated based on long-lived phosphorescent signal. A phosphorescent dinuclear iridium(III) complex Ir1 has been designed and synthesized, which exhibits excellent optical properties, such as high quantum yields, large Stokes shift, high photostability and long emission lifetime. The phosphorescent intensity and lifetime of complex are very sensitive to oxygen levels. Thus, the application of Ir1 for monitoring intracellular oxygen levels has been realized successfully...
July 11, 2016: Optics Express
Sean P Kearney, Daniel R Guildenbecher
We apply ultrafast pure-rotational coherent anti-Stokes Raman scattering (CARS) for temperature and relative oxygen concentration measurements in the plume emanating from a burning, aluminized ammonium-perchlorate propellant strand. Combustion of these metal-based propellants is a particularly hostile environment for laser-based diagnostics, with intense background luminosity and scattering from hot metal particles as large as several hundred micrometers in diameter. CARS spectra that were previously obtained using nanosecond pulsed lasers in an aluminum-particle-seeded flame are examined and are determined to be severely impacted by nonresonant background, presumably as a result of the plasma formed by particulate-enhanced laser-induced breakdown...
June 20, 2016: Applied Optics
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