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fluorescence lifetime imaging microscopy

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https://www.readbyqxmd.com/read/28323249/local-density-of-electromagnetic-states-in-plasmonic-nanotapers-spatial-resolution-limits-with-nitrogen-vacancy-centers-in-diamond-nanospheres
#1
Rafael Salas-Montiel, Martin Berthel, Josslyn Beltrán-Madrigal, Serge Huant, Aurélien Drezet, Sylvain Blaize
One of the most explored single quantum emitters for the development of nanoscale fluorescence lifetime imaging is the nitrogen-vacancy (NV) color center in diamond. Indeed, a NV center does not experience fluorescence bleaching and blinking at room temperature. Furthermore, its optical properties are preserved when embedded into nanodiamond hosts. This letter focuses on the modeling of the local density of states (LDOS) in a plasmonic nanofocusing structure with NV center acting as local illumination sources...
March 21, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28294329/multidie-led-combined-with-homogenizing-optics-to-improve-frequency-response-and-intensity-for-flim-applications
#2
H-T Liu, W-L Lin, Y-L Feng, Y Lin, Y-C Chen
Application of light-emitting diodes (LEDs) in frequency-domain fluorescence lifetime imaging microscopy (FLIM) has been limited by the trade-off between modulation frequency and illumination intensity of LEDs, which affects the signal-to-noise ratio in fluorescence lifetime measurements. To increase modulation frequency without sacrificing output power of LEDs, we propose to use LEDs with multiple dice connected in series. The LED capacitance was reduced with series connection; therefore, the frequency response of multidie LED was significantly increased...
March 15, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28286806/assessment-of-cellular-redox-state-using-nad-p-h-fluorescence-intensity-and-lifetime
#3
Thomas S Blacker, Tunde Berecz, Michael R Duchen, Gyorgy Szabadkai
NADH and NADPH are redox cofactors, primarily involved in catabolic and anabolic metabolic processes respectively. In addition, NADPH plays an important role in cellular antioxidant defence. In live cells and tissues, the intensity of their spectrally-identical autofluorescence, termed NAD(P)H, can be used to probe the mitochondrial redox state, while their distinct enzyme-binding characteristics can be used to separate their relative contributions to the total NAD(P)H intensity using fluorescence lifetime imaging microscopy (FLIM)...
January 20, 2017: Bio-protocol
https://www.readbyqxmd.com/read/28285819/imaging-erk-and-pka-activation-in-single-dendritic-spines-during-structural-plasticity
#4
Shen Tang, Ryohei Yasuda
Extracellular signal-regulated kinase (ERK) and protein kinase A (PKA) play important roles in LTP and spine structural plasticity. While fluorescence resonance energy transfer (FRET)-based sensors for these kinases had previously been developed, they did not provide sufficient sensitivity for imaging small neuronal compartments, such as single dendritic spines in brain slices. Here we improved the sensitivity of FRET-based kinase sensors for monitoring kinase activity under two-photon fluorescence lifetime imaging microscopy (2pFLIM)...
March 22, 2017: Neuron
https://www.readbyqxmd.com/read/28278199/monitoring-integrity-and-localization-of-modified-single-stranded-rna-oligonucleotides-using-ultrasensitive-fluorescence-methods
#5
Philipp Heissig, Waldemar Schrimpf, Philipp Hadwiger, Ernst Wagner, Don C Lamb
Short single-stranded oligonucleotides represent a class of promising therapeutics with diverse application areas. Antisense oligonucleotides, for example, can interfere with various processes involved in mRNA processing through complementary base pairing. Also RNA interference can be regulated by antagomirs, single-stranded siRNA and single-stranded microRNA mimics. The increased susceptibility to nucleolytic degradation of unpaired RNAs can be counteracted by chemical modification of the sugar phosphate backbone...
2017: PloS One
https://www.readbyqxmd.com/read/28255707/studying-dynamic-plasma-membrane-binding-of-tcr-cd3-chains-during-immunological-synapse-formation-using-donor-quenching-fret-and-flim-fret
#6
Etienne Gagnon, Audrey Connolly, Jessica Dobbins, Kai W Wucherpfennig
Over the last decade, advancements in the time and space resolution of microscopy technologies have enabled dissection of the molecular events involved in T cell Immunological Synapse (IS) formation. Using a combination of Förster Resonance Energy Transfer (FRET) and Fluorescence Lifetime Imagining Microscopy (FLIM), we have demonstrated dynamic plasma membrane binding by cytoplasmic domains of T cell receptor (TCR)-associated CD3 chains and other T cell transmembrane receptors. We have developed methods for imaging such membrane binding both at steady state and during receptor triggering at the IS...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28252014/revealing-the-sequence-of-interactions-of-puroa-peptide-with-candida-albicans-cells-by-live-cell-imaging
#7
Nadin Shagaghi, Mrinal Bhave, Enzo A Palombo, Andrew H A Clayton
To determine the mechanism(s) of action of antimicrobial peptides (AMPs) it is desirable to provide details of their interaction kinetics with cellular, sub-cellular and molecular targets. The synthetic peptide, PuroA, displays potent antimicrobial activities which have been attributed to peptide-induced membrane destabilization, or intracellular mechanisms of action (DNA-binding) or both. We used time-lapse fluorescence microscopy and fluorescence lifetime imaging microscopy (FLIM) to directly monitor the localization and interaction kinetics of a FITC- PuroA peptide on single Candida albicans cells in real time...
March 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28250053/two-photon-intravital-fluorescence-lifetime-imaging-of-the-kidney-reveals-cell-type-specific-metabolic-signatures
#8
Takashi Hato, Seth Winfree, Richard Day, Ruben M Sandoval, Bruce A Molitoris, Mervin C Yoder, Roger C Wiggins, Yi Zheng, Kenneth W Dunn, Pierre C Dagher
In the live animal, tissue autofluorescence arises from a number of biologically important metabolites, such as the reduced form of nicotinamide adenine dinucleotide. Because autofluorescence changes with metabolic state, it can be harnessed as a label-free imaging tool with which to study metabolism in vivo Here, we used the combination of intravital two-photon microscopy and frequency-domain fluorescence lifetime imaging microscopy (FLIM) to map cell-specific metabolic signatures in the kidneys of live animals...
March 1, 2017: Journal of the American Society of Nephrology: JASN
https://www.readbyqxmd.com/read/28230071/probing-the-molecular-mechanism-of-human-soluble-guanylate-cyclase-activation-by-no-in-vitro-and-in-vivo
#9
Jie Pan, Hong Yuan, Xiaoxue Zhang, Huijuan Zhang, Qiming Xu, Yajun Zhou, Li Tan, Shingo Nagawa, Zhong-Xian Huang, Xiangshi Tan
Soluble guanylate cyclase (sGC) is a heme-containing metalloprotein in NO-sGC-cGMP signaling. NO binds to the heme of sGC to catalyze the synthesis of the second messenger cGMP, which plays a critical role in several physiological processes. However, the molecular mechanism for sGC to mediate the NO signaling remains unclear. Here fluorophore FlAsH-EDT2 and fluorescent proteins were employed to study the NO-induced sGC activation. FlAsH-EDT2 labeling study revealed that NO binding to the H-NOX domain of sGC increased the distance between H-NOX and PAS domain and the separation between H-NOX and coiled-coil domain...
February 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28211922/applying-phasor-approach-analysis-of-multiphoton-flim-measurements-to-probe-the-metabolic-activity-of-three-dimensional-in-vitro-cell-culture-models
#10
Pirmin H Lakner, Michael G Monaghan, Yvonne Möller, Monilola A Olayioye, Katja Schenke-Layland
Fluorescence lifetime imaging microscopy (FLIM) can measure and discriminate endogenous fluorophores present in biological samples. This study seeks to identify FLIM as a suitable method to non-invasively detect a shift in cellular metabolic activity towards glycolysis or oxidative phosphorylation in 3D Caco-2 models of colorectal carcinoma. These models were treated with potassium cyanide or hydrogen peroxide as controls, and epidermal growth factor (EGF) as a physiologically-relevant influencer of cell metabolic behaviour...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28199849/quantitative-flim-fret-microscopy-to-monitor-nanoscale-chromatin-compaction-in%C3%A2-vivo-reveals-structural-roles-of-condensin-complexes
#11
David Llères, Aymeric P Bailly, Aurélien Perrin, David G Norman, Dimitris P Xirodimas, Robert Feil
How metazoan genomes are structured at the nanoscale in living cells and tissues remains unknown. Here, we adapted a quantitative FRET (Förster resonance energy transfer)-based fluorescence lifetime imaging microscopy (FLIM) approach to assay nanoscale chromatin compaction in living organisms. Caenorhabditis elegans was chosen as a model system. By measuring FRET between histone-tagged fluorescent proteins, we visualized distinct chromosomal regions and quantified the different levels of nanoscale compaction in meiotic cells...
February 14, 2017: Cell Reports
https://www.readbyqxmd.com/read/28198734/new-frontiers-in-intravital-microscopy-of-the-kidney
#12
Andrew M Hall, Claus D Schuh, Dominik Haenni
PURPOSE OF REVIEW: Intravital imaging with multiphoton microscopy enables the detailed study of dynamic cellular processes within functioning organs in living animals, in ways that would not otherwise be possible. It therefore represents a powerful tool in translational kidney research. In this article, we will discuss several new technical developments that have significantly increased the capabilities of kidney imaging. RECENT FINDINGS: Important contemporary advances in biomedical imaging technology include longer wavelength excitation lasers, far-red emitting fluorescent reporters, highly sensitive detectors, fluorescence lifetime measurements, adaptive optics, microendoscopes, high-throughput automated analysis algorithms and tissue clearing techniques...
February 13, 2017: Current Opinion in Nephrology and Hypertension
https://www.readbyqxmd.com/read/28193235/dynamic-presenilin-1-and-synaptotagmin-1-interaction-modulates-exocytosis-and-amyloid-%C3%AE-production
#13
Katarzyna Marta Zoltowska, Masato Maesako, Iryna Lushnikova, Shuko Takeda, Laura J Keller, Galina Skibo, Bradley T Hyman, Oksana Berezovska
BACKGROUND: Alzheimer's disease (AD)-linked protein, presenilin 1 (PS1), is present at the synapse, and the knock-out of presenilin in mice leads to synaptic dysfunction. On the other hand, synaptic activity was shown to influence PS1-dependent generation of distinct amyloid β (Aβ) species. However, the precise nature of these regulations remains unclear. The current study reveals novel role of PS1 at the synapse, and deciphers how PS1 and synaptic vesicle-associated protein, synaptotagmin 1 (Syt1) modulate each other functions in neurons via direct activity-triggered interaction...
February 13, 2017: Molecular Neurodegeneration
https://www.readbyqxmd.com/read/28168255/do-grain-boundaries-dominate-non-radiative-recombination-in-ch3nh3pbi3-perovskite-thin-films
#14
Mengjin Yang, Yining Zeng, Zhen Li, Dong Hoe Kim, Chun-Sheng Jiang, Jao van de Lagemaat, Kai Zhu
Here, we examine grain boundaries (GBs) with respect to non-GB regions (grain surfaces (GSs) and grain interiors (GIs)) in high-quality micrometer-sized perovskite CH3NH3PbI3 (or MAPbI3) thin films using high-resolution confocal fluorescence-lifetime imaging microscopy in conjunction with kinetic modeling of charge-transport and recombination processes. We show that, contrary to previous studies, GBs in our perovskite MAPbI3 thin films do not lead to increased recombination but that recombination in these films happens primarily in the non-GB regions (i...
February 7, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28134273/imaging-tumor-microscopic-viscosity-in-vivo-using-molecular-rotors
#15
Lyubov' E Shimolina, Maria Angeles Izquierdo, Ismael López-Duarte, James A Bull, Marina V Shirmanova, Larisa G Klapshina, Elena V Zagaynova, Marina K Kuimova
The microscopic viscosity plays an essential role in cellular biophysics by controlling the rates of diffusion and bimolecular reactions within the cell interior. While several approaches have emerged that have allowed the measurement of viscosity and diffusion on a single cell level in vitro, the in vivo viscosity monitoring has not yet been realized. Here we report the use of fluorescent molecular rotors in combination with Fluorescence Lifetime Imaging Microscopy (FLIM) to image microscopic viscosity in vivo, both on a single cell level and in connecting tissues of subcutaneous tumors in mice...
January 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28129796/two-photon-flim-of-nad-p-h-and-fad-in-mesenchymal-stem-cells-undergoing-either-osteogenic-or-chondrogenic-differentiation
#16
Aleksandra V Meleshina, Varvara V Dudenkova, Alena S Bystrova, Daria S Kuznetsova, Marina V Shirmanova, Elena V Zagaynova
BACKGROUND: Metabolic plasticity and the versatility of different lineages of stem cells as they satisfy their energy demands are not completely understood. In this study we investigated the metabolic changes in mesenchymal stem cells (MSCs) undergoing differentiation in two directions, osteogenic and chondrogenic, using two-photon fluorescence microscopy combined with FLIM. METHODS: Differentiation was induced by incubating the human bone marrow MSCs in osteogenic or chondrogenic mediums...
January 28, 2017: Stem Cell Research & Therapy
https://www.readbyqxmd.com/read/28125231/improved-fluorescent-protein-contrast-and-discrimination-by-optically-controlling-dark-state-lifetimes
#17
Yen-Cheng Chen, Robert M Dickson
Modulation and optical control of photoswitchable fluorescent protein (PS-FP) dark state lifetimes drastically improves sensitivity and selectivity in fluorescence imaging. The dark state population of PS-FPs generates an out-of-phase fluorescence component relative to the sinusoidally modulated 488 nm laser excitation. Because this apparent phase advanced emission results from slow recovery to the fluorescent manifold, we hasten recovery and, therefore, modulation frequency by varying coillumination intensity at 405 nm...
February 16, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28115230/time-resolved-fluorescence-microscopy-flim-as-an-analytical-tool-in-skin-nanomedicine
#18
REVIEW
Ulrike Alexiev, Pierre Volz, Alexander Boreham, Robert Brodwolf
The emerging field of nanomedicine provides new approaches for the diagnosis and treatment of diseases, for symptom relief, and for monitoring of disease progression. Topical application of drug-loaded nanoparticles for the treatment of skin disorders is a promising strategy to overcome the stratum corneum, the upper layer of the skin, which represents an effective physical and biochemical barrier. The understanding of drug penetration into skin and enhanced penetration into skin facilitated by nanocarriers requires analytical tools that ideally allow to visualize the skin, its morphology, the drug carriers, drugs, their transport across the skin and possible interactions, as well as effects of the nanocarriers within the different skin layers...
January 21, 2017: European Journal of Pharmaceutics and Biopharmaceutics
https://www.readbyqxmd.com/read/28114413/visualization-of-bri1-and-serk3-bak1-nanoclusters-in-arabidopsis-roots
#19
Stefan J Hutten, Danny S Hamers, Marije Aan den Toorn, Wilma van Esse, Antsje Nolles, Christoph A Bücherl, Sacco C de Vries, Johannes Hohlbein, Jan Willem Borst
Brassinosteroids (BRs) are plant hormones that are perceived at the plasma membrane (PM) by the ligand binding receptor BRASSINOSTEROID-INSENSITIVE1 (BRI1) and the co-receptor SOMATIC EMBRYOGENESIS RECEPTOR LIKE KINASE 3/BRI1 ASSOCIATED KINASE 1 (SERK3/BAK1). To visualize BRI1-GFP and SERK3/BAK1-mCherry in the plane of the PM, variable-angle epifluorescence microscopy (VAEM) was employed, which allows selective illumination of a thin surface layer. VAEM revealed an inhomogeneous distribution of BRI1-GFP and SERK3/BAK1-mCherry at the PM, which we attribute to the presence of distinct nanoclusters...
2017: PloS One
https://www.readbyqxmd.com/read/28096507/de-novo-phosphorylation-and-conformational-opening-of-the-tyrosine-kinase-lck-act-in-concert-to-initiate-t-cell-receptor-signaling
#20
Lars Philipsen, Amarendra V Reddycherla, Roland Hartig, Janine Gumz, Matthias Kästle, Andreas Kritikos, Mateusz P Poltorak, Yury Prokazov, Evgeny Turbin, André Weber, Werner Zuschratter, Burkhart Schraven, Luca Simeoni, Andreas J Müller
The enzymatic activity of the Src family tyrosine kinase p56(Lck) (Lck) is tightly controlled by differential phosphorylation of two tyrosine residues, Tyr(394) and Tyr(505) Phosphorylation of Tyr(394) and the conformational opening of Lck are believed to activate the kinase, whereas Tyr(505) phosphorylation is thought to generate a closed, inactive conformation of Lck. We investigated whether the conformation of Lck and its phosphorylation state act in concert to regulate the initiation of T cell receptor (TCR) signaling...
January 17, 2017: Science Signaling
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