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Two photon microscopy

Hanna Thomsen, Fabrice E Graf, Anne Farewell, Marica B Ericson
One pertinent complication in bacterial infection is the growth of biofilms, i.e., communities of surface-adhered bacteria resilient to antibiotics. Photodynamic inactivation has been proposed as an alternative to antibiotic treatment; however, novel techniques complementing standard efficacy measures are required. Herein, we present an approach employing multiphoton microscopy complemented with Airyscan super-resolution microscopy, to visualize the distribution of curcumin in Staphylococcus epidermidis biofilms...
May 21, 2018: Journal of Biophotonics
Bingqiong Wang, Yameng Sun, Jialing Zhou, Xiaoning Wu, Shuyan Chen, Shanshan Wu, Hui Liu, Tailing Wang, Xiaojuan Ou, Jidong Jia, Hong You
Hepatitis B (HBV)-related fibrosis can be reversed after effective antiviral therapy. However, detailed changes of collagen characteristics during fibrosis regression remain unclear. Paired biopsy samples obtained from chronic hepatitis B patients were imaged with second harmonic generation/two photon excitation fluorescence (SHG/TPEF)-based microscopy to identify and quantify collagen features in portal, septal, and fibrillar areas. According to the changes of Ishak stage and qFibrosis score, a total of 117 patients with paired liver biopsy appeared to have four different outcomes after 78-week antiviral therapy: fast reverse (9%), reverse (63%), stable (15%), or progress (13%) on fibrosis...
May 21, 2018: Modern Pathology: An Official Journal of the United States and Canadian Academy of Pathology, Inc
James R Eles, Alberto L Vazquez, Takashi D Y Kozai, X Tracy Cui
Implantable electrode devices enable long-term electrophysiological recordings for brain-machine interfaces and basic neuroscience research. Implantation of these devices, however, leads to neuronal damage and progressive neural degeneration that can lead to device failure. The present study uses in vivo two-photon microscopy to study the calcium activity and morphology of neurons before, during, and one month after electrode implantation to determine how implantation trauma injures neurons. We show that implantation leads to prolonged, elevated calcium levels in neurons within 150 μm of the electrode interface...
May 7, 2018: Biomaterials
Mattias Bood, Anders F Füchtbauer, Moa S Wranne, Jong Jin Ro, Sangamesh Sarangamath, Afaf H El-Sagheer, Déborah L M Rupert, Rachel S Fisher, Steven W Magennis, Anita C Jones, Fredrik Höök, Tom Brown, Byeang Hyean Kim, Anders Dahlén, L Marcus Wilhelmsson, Morten Grøtli
Emissive base analogs are powerful tools for probing nucleic acids at the molecular level. Herein we describe the development and thorough characterization of pentacyclic adenine (pA), a versatile base analog with exceptional fluorescence properties. When incorporated into DNA, pA pairs selectively with thymine without perturbing the B-form structure and is among the brightest nucleobase analogs reported so far. Together with the recently established base analog acceptor qAnitro , pA allows accurate distance and orientation determination via Förster resonance energy transfer (FRET) measurements...
April 14, 2018: Chemical Science
Nancy I Lewis, Jennifer L Wolny, John Claude Achenbach, Lee Ellis, Joseph S Pitula, Cheryl Rafuse, Detbra S Rosales, Pearse McCarron
Benthic dinoflagellates of the toxigenic genus Coolia Meunier (Dinophyceae) are known to have a global distribution in both tropical and temperate waters. The type species, C. monotis, has been reported from the Mediterranean Sea, the NE Atlantic and from Rhode Island, USA in the NW Atlantic, whereas other species in the genus have been reported from tropical locations. Coolia cells were observed in algal drift samples collected at seven sites in Nova Scotia, Canada. Clonal isolates were established from four of these locations and identified with light and scanning electron microscopy, then confirmed with genetic sequencing to be C...
May 2018: Harmful Algae
Sourav Sahoo, Sucheta Mondal, Gwilym Williams, Andrew May, Sam Ladak, Anjan Barman
Three-dimensional magnetic nanostructures are now attracting intense interest due to their potential as ultrahigh density future magnetic storage devices. Here, we report on the study of ultrafast magnetization dynamics of a complex three-dimensional magnetic nanostructure. Arrays of magnetic tetrapod structures were fabricated using a combination of two-photon lithography (TPL) and electrodeposition. All-optical time-resolved magneto-optical Kerr microscopy was exploited to probe the spin-wave modes from the junction of a single tetrapod structure...
May 17, 2018: Nanoscale
Kenneth Squire, Xianming Kong, Paul LeDuff, Gregory L Rorrer, Alan X Wang
Fluorescence biosensing is one of the most established biosensing methods, particularly fluorescence spectroscopy and microscopy. These are two highly sensitive techniques but require high grade electronics and optics to achieve the desired sensitivity. Efforts have been made to implement these methods using consumer grade electronics and simple optical setups for applications such as point-of-care diagnostics, but the sensitivity inherently suffers. Sensing substrates, capable of enhancing fluorescence are thus needed to achieve high sensitivity for such applications...
May 16, 2018: Journal of Biophotonics
Hui Cai, Bin Chen, Mark Blei, Shery L Y Chang, Kedi Wu, Houlong Zhuang, Sefaattin Tongay
Akin to the enormous number of discoveries made through traditional semiconductor alloys, alloying selected 2D semiconductors enables engineering of their electronic structure for a wide range of new applications. 2D alloys have been demonstrated when two components crystallized in the same phase, and their bandgaps displayed predictable monotonic variation. By stabilizing previously unobserved compositions and phases of GaSe1-x Te x at nanoscales on GaAs(111), we demonstrate abnormal band bowing effects and phase instability region when components crystallize in different phases...
May 15, 2018: Nature Communications
Minhaeng Cho
Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams...
May 14, 2018: Journal of Chemical Physics
Kyo Koizumi, Masatoshi Inoue, Srikanta Chowdhury, Haruhiko Bito, Akihiro Yamanaka, Toru Ishizuka, Hiromu Yawo
To investigate how the functional architecture is organized in layer 5 (L5) of the somatosensory cortex of a mouse in vivo, the input-output relationship was investigated using an all-optical approach. The neural activity in L5 was optically recorded using a Ca2+ sensor, R-CaMP2, through a microprism inserted in the cortex under two-photon microscopy, while the L5 was regionally excited using optogenetics. The excitability was spread around the blue-light irradiated region, but the horizontal propagation was limited to within a certain distance (λ < 130 μm from the center of the illumination spot)...
May 14, 2018: Journal of Physiological Sciences: JPS
Shu Wang, Huiping Du, Bingbing Lin, Chenxi Liao, Xiaoqin Zhu, Xingfu Wang, Hong Chen, Shuangmu Zhuo, Liwei Jiang, Lianhuang Li, Haohua Tu, Jianxin Chen
Ischemic stroke is a leading cause of death and permanent disability worldwide. Middle cerebral artery occlusion (MCAO) of variable duration times could be anticipated to result in varying degrees of injury that evolve spatially over time. Therefore, investigations following strokes require information concerning the spatiotemporal dimensions of the ischemic core as well as of perilesional areas. In the present study, multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) was applied to image such pathophysiological events...
May 1, 2018: Biomedical Optics Express
Kriti Charan, Bo Li, Mengran Wang, Charles P Lin, Chris Xu
Deep tissue multiphoton imaging requires high peak power to enhance signal and low average power to prevent thermal damage. Both goals can be advantageously achieved through laser repetition rate tuning instead of simply adjusting the average power. We show that the ideal repetition rate for deep two-photon imaging in the mouse brain is between 1 and 10 MHz, and we present a fiber-based source with an arbitrarily tunable repetition rate within this range. The performance of the new source is compared to a mode-locked Ti:Sapphire (Ti:S) laser for in vivo imaging of mouse brain vasculature...
May 1, 2018: Biomedical Optics Express
M Kaufmann, M L Hupfer, T Sachse, F Herrmann-Westendorf, D Weiß, B Dietzek, R Beckert, M Presselt
HYPOTHESIS: Supramolecular structures determine properties of optoelectronically active materials and can be tailored via the Langmuir-Blodgett (LB) technique. Interactions between dyes can cause high crystallinities of Langmuir monolayers, thus rendering retaining their integrity during the LB-deposition challenging. However, increasing degrees of freedom exclusively at the polar anchoring moieties of dyes might improve processability without perturbing the dye's optoelectronic properties nor the function-determining crystallinity of the layer...
April 30, 2018: Journal of Colloid and Interface Science
Paul Shin, WooJhon Choi, JongYoon Joo, Wang-Yuhl Oh
Functional hyperemia in the rat cortex was investigated using high-speed optical coherence tomography (OCT) angiography and Doppler OCT. OCT angiography (OCTA) was performed to image the hemodynamic stimulus-response over a wide field of view. Temporal changes in vessel diameters in different vessel compartments, which were determined as the diameters of erythrocyte flows in OCT angiograms, were measured in order to monitor localized hemodynamic changes. Our results showed that the dilation of arterioles at the site of activation was accompanied by the dilation of upstream arteries...
January 1, 2018: Journal of Cerebral Blood Flow and Metabolism
Won Hyuk Jang, Soonjae Kwon, Sehwan Shim, Won-Suk Jang, Jae Kyung Myung, Sejung Yang, Sunhoo Park, Ki Hean Kim
Cutaneous radiation injury (CRI) is a skin injury caused by high dose exposure of ionizing radiation (IR). For proper treatment, early detection of CRI before clinical symptoms is important. Optical microscopic techniques such as reflectance confocal microscopy (RCM) and two-photon microscopy (TPM) have been tested as the early diagnosis method by detecting cellular changes. In this study, RCM and TPM were compared in the detection of cellular changes caused by CRI in an in-vivo mouse model. CRI was induced on the mouse hindlimb skin with various IR doses and the injured skin regions were imaged longitudinally by both modalities until the onset of clinical symptoms...
May 12, 2018: Journal of Biophotonics
Clément Ricard, Erica D Arroyo, Cynthia X He, Carlos Portera-Cailliau, Gabriel Lepousez, Marco Canepari, Daniel Fiole
Imaging the brain of living laboratory animals at a microscopic scale can be achieved by two-photon microscopy thanks to the high penetrability and low phototoxicity of the excitation wavelengths used. However, knowledge of the two-photon spectral properties of the myriad fluorescent probes is generally scarce and, for many, non-existent. In addition, the use of different measurement units in published reports further hinders the design of a comprehensive imaging experiment. In this review, we compile and homogenize the two-photon spectral properties of 280 fluorescent probes...
May 11, 2018: Brain Structure & Function
Rui Chen, Shuhao Shen, Nanguang Chen
A spatiotemporal phase modulator (STPM) is theoretically investigated using the vectorial diffraction theory. The STPM is equivalent to a time-dependent phase-only pupil filter that alternates between a homogeneous filter and a stripe-shaped filter with a sinusoidal phase distribution. It is found that two-photon focal modulation microscopy (TPFMM) using this STPM can significantly suppress the background contribution from out-of-focus ballistic excitation and achieve almost the same resolution as two-photon microscopy...
May 2018: Journal of Biomedical Optics
Sang A Park, Young Ho Choe, Eunji Park, Young-Min Hyun
Neutrophils are highly motile innate immune cells; they actively migrate in response to inflammatory signals. Using two-photon intravital microscopy, we discovered that neutrophils form stable clusters upon phototoxicity at a certain threshold. Without significant damage to the collagen structure of mouse dermis, neutrophils aggregated together with nearby neutrophils. Surprisingly, this in situ neutrophil clustering resulted in rigorous changes of migratory direction. The density of residing neutrophils was also a critical factor affecting clustering...
May 7, 2018: Cell Adhesion & Migration
Norbert Kiss, Dóra Haluszka, Kende Lőrincz, Enikő Kuroli, Judit Hársing, Balázs Mayer, Sarolta Kárpáti, György Fekete, Róbert Szipőcs, Norbert Wikonkál, Márta Medvecz
Ehlers-Danlos syndrome (EDS) is the name for a heterogenous group of rare genetic connective tissue disorders with an overall incidence of 1 in 5000. The histological characteristics of EDS have been previously described in detail in the late 1970s and early 1980s. Since that time, the classification of EDS has undergone significant changes, yet the description of the histological features of collagen morphology in different EDS subtypes has endured the test of time. Nonlinear microscopy techniques can be utilized for non-invasive in vivo label-free imaging of the skin...
May 3, 2018: Archives of Dermatological Research
Nicole Reichenbach, Andrea Delekate, Björn Breithausen, Kevin Keppler, Stefanie Poll, Theresa Schulte, Jan Peter, Monika Plescher, Jan N Hansen, Nelli Blank, Armin Keller, Martin Fuhrmann, Christian Henneberger, Annett Halle, Gabor C Petzold
Astrocytic hyperactivity is an important contributor to neuronal-glial network dysfunction in Alzheimer's disease (AD). We have previously shown that astrocyte hyperactivity is mediated by signaling through the P2Y1 purinoreceptor (P2Y1R) pathway. Using the APPPS1 mouse model of AD, we here find that chronic intracerebroventricular infusion of P2Y1R inhibitors normalizes astroglial and neuronal network dysfunction, as measured by in vivo two-photon microscopy, augments structural synaptic integrity, and preserves hippocampal long-term potentiation...
May 3, 2018: Journal of Experimental Medicine
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