Journal: Methods and Applications in Fluorescence

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IOP Publishing

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ISSN

2050-6120

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2015 - 20204
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Publications 1 - 4 of 4
  • A sensitive near infrared to near-infrared luminescence nanothermometer based on triple doped Ln -Y2O3
    Item type: Journal Article
    Porosnicu, Ioana; Colbea, Claudiu; Baiasu, Flaviu; et al. (2020)
    Methods and Applications in Fluorescence
    In recent years, luminescence nanothermometers with near infrared light (NIR) emission excited in the NIR range have attracted much attention due to their potential in bio applications. Here, we propose a new nanothermometer based on triple doped 1%Ho, 1%Er, 1%Yb - Y2O3 that operates in the second and third biological windows around 1200 and 1530 nm under pulsed excitation at 905 nm. The NIR emissions were analysed in the temperature range of 298-473 K in terms of intensity, shape and dynamics. The nanothermometer performances were described using the luminescent intensity ratio (LIR) corresponding to the 5I6-5I8 and 4I13/2-4I15/2 emissions transitions of Ho and Er, respectively. A maximum relative sensitivity of 1.5% K-1 was achieved at 309 K, which is among the highest five values reported so far for the NIR to NIR downconversion nanothermometers. The thermometer performance for biological application was assessed in terms of nanothermometer reliability and stability as well as emission shape changes induced by water and custom designed optical phantoms. Combination between use of pulsed excitation and identification of Ln doping configuration offering both excitation and emission in the biological windows represent a solid approach that can be easily translated to other hosts to develop a new class of near infrared nanothermometers. © 2020 IOP Publishing Ltd.
  • Single-molecule chemistry. Part I: monitoring oxidation of G in oligonucleotides using CY3 fluorescence
    Item type: Journal Article
    Sobek, Jens; Schmidt, Marco; Grossmann, Jonas; et al. (2020)
    Methods and Applications in Fluorescence
    Single-molecule hybridisation of CY3 dye labelled short oligonucleotides to surface immobilised probes was investigated in zero-mode waveguide nanostructures using a modified DNA sequencer. At longer measuring times, we observed changes of the initial hybridisation fluorescence pulse pattern which we attribute to products created by chemical reactions at the nucleobases. The origin is a charge separated state created by a photoinduced electron transfer from nucleobases to the dye followed by secondary reactions with oxygen and water, respectively. The positive charge can migrate through the hybrid resulting in base modifications at distant sites. Static fluorescence spectra were recorded in order to determine the properties of CY3 stacking to different base pairs, and compared to pulse intensities. A characteristic pulse pattern change was assigned to the oxidation of G to 8-oG besides the formation of a number of secondary products that are not yet identified. Further, we present a method to visualise the degree of chemical reactions to gain an overview of ongoing processes. Our study demonstrates that CY3 is able to oxidise nucleobases in ds DNA, and also in ss overhangs. An important finding is the correlation between nucleobase oxidation potential and fluorescence quenching which explains the intensity changes observed in single molecule measurements. The analysis of fluorescence traces provides the opportunity to track complete and coherent reaction sequences enabling to follow the fate of a single molecule over a long period of time, and to observe chemical reactions in real-time. This opens up the opportunity to analyse reaction pathways, to detect new products and short-lived intermediates, and to investigate rare events due to the large number of single molecules observed in parallel.
  • Single-molecule DNA hybridisation studied by using a modified DNA sequencer: a comparison with surface plasmon resonance data
    Item type: Journal Article
    Sobek, Jens; Rehrauer, Hubert; Schauer, Stefan; et al. (2016)
    Methods and Applications in Fluorescence
  • Dual color single particle tracking via nanobodies
    Item type: Journal Article
    Albrecht, David; Winterflood, Christian M.; Ewers, Helge (2015)
    Methods and Applications in Fluorescence
    Single particle tracking is a powerful tool to investigate the function of biological molecules by following their motion in space. However, the simultaneous tracking of two different species of molecules is still difficult to realize without compromising the length or density of trajectories, the localization accuracy or the simplicity of the assay. Here, we demonstrate a simple dual color single particle tracking assay using small, bright, high-affinity labeling via nanobodies of accessible targets with widely available instrumentation. We furthermore apply a ratiometric step-size analysis method to visualize differences in apparent membrane viscosity.
Publications 1 - 4 of 4