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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
Zhong-Xiao Man, Yun-Jie Xia, Nguyen Ba An
We theoretically study wave-particle duality of two entangled photons in the spirit of quantum version of delayed-choice experiments using Hadamard gate controlled by the quantum state of an ancilla and show that the two photons may globally exhibit particle-like, wave-like or simultaneously both particle-like and wave-like behavior. We prove that the obtained results cannot be satisfactorily explained by any hidden-variable theory. We also propose an efficient and experimentally feasible scheme without using any ancilla and controlled-gates to directly (i...
February 13, 2017: Scientific Reports
Zhen Zhao, Tanja Vajen, Ela Karshovska, Annemiek Dickhout, Martin M Schmitt, Remco T A Megens, Philipp von Hundelshausen, Thomas A Koeppel, Tilman M Hackeng, Christian Weber, Rory R Koenen
Platelets play an important role in the pathogenesis of vascular remodelling after injury. Junctional adhesion molecule A (JAM-A) was recently described to regulate platelet activation. Specific deletion of JAM-A from platelets resulted in increased reactivity and in accelerated progression of atherosclerosis. The aim of this study was to investigate the specific contribution of platelet-derived JAM-A to neointima formation after vascular injury. Mice with or without platelet-specific (tr)JAM-A-deficiency in an apolipoprotein e (apoe(-/-) ) background underwent wire-induced injury of the common carotid artery...
February 17, 2017: Journal of Cellular and Molecular Medicine
Maciej Modzel, Frederik W Lund, Daniel Wüstner
Cellular cholesterol homeostasis relies on precise control of the sterol content of organelle membranes. Obtaining insight into cholesterol trafficking pathways and kinetics by live-cell imaging relies on two conditions. First, one needs to develop suitable analogs that resemble cholesterol as closely as possible with respect to their biophysical and biochemical properties. Second, the cholesterol analogs should have good fluorescence properties. This interferes, however, often with the first requirement, such that the imaging instrumentation must be optimized to collect photons from suboptimal fluorophores, but good cholesterol mimics, such as the intrinsically fluorescent sterols, cholestatrienol (CTL) or dehydroergosterol (DHE)...
2017: Methods in Molecular Biology
M Gabriele Bixel, Anjali P Kusumbe, Saravana K Ramasamy, Kishor K Sivaraj, Stefan Butz, Dietmar Vestweber, Ralf H Adams
Measurements of flow velocities at the level of individual arterial vessels and sinusoidal capillaries are crucial for understanding the dynamics of hematopoietic stem and progenitor cell homing in the bone marrow vasculature. We have developed two complementary intravital two-photon imaging approaches to determine blood flow dynamics and velocities in multiple vessel segments by capturing the motion of red blood cells. High-resolution spatiotemporal measurements through a cranial window to determine short-time dynamics of flowing blood cells and repetitive centerline scans were used to obtain a detailed flow-profile map with hemodynamic parameters...
February 14, 2017: Cell Reports
Daniel R Richardson, Sukesh Roy, James R Gord
Two-photon, planar laser-induced fluorescence (TP-PLIF) of carbon monoxide was performed in steady and driven flames using femtosecond (fs) laser pulses at 1 kHz. Excitation radiation at 230.1 nm (full-width at half-maximum bandwidth of 270  cm<sup>-1</sup>) was used to pump many rovibrational two-photon transitions in the B<sup>1</sup>∑<sup>+</sup>←X<sup>1</sup>∑<sup>+</sup> system. Visible fluorescence in the range 362-516 nm was captured using an image intensifier and high-speed camera...
February 15, 2017: Optics Letters
Liang Yang, Dongdong Qian, Chen Xin, Zhijiang Hu, Shengyun Ji, Dong Wu, Yanlei Hu, Jiawen Li, Wenhao Huang, Jiaru Chu
In this Letter, superposed Bessel beams (SBBs) are realized by alternatively imprinting holograms of opposite-order Bessel beams along the radial direction on a spatial light modulator. The propagation invariance and non-rotation properties of SBBs are theoretically predicted and experimentally demonstrated. The focusing property of SBBs with a high numerical aperture (NA) objective is investigated with the Debye vectorial diffraction theory. Near the focal plane, a circularly distributed multiple foci pattern is achieved...
February 15, 2017: Optics Letters
Huihong Lin, Ting Yu, Gongxun Bai, Qinyuan Zhang, Jianhua Hao
Near-infrared-to-near-infrared (NIR-to-NIR) anti-Stokes luminescence from Cr<sup>3+</sup> singly doped Ca<sub>3</sub>Ga<sub>2</sub>Ge<sub>3</sub>O<sub>12</sub> (CGGG) occurs under the excitation of an 808 nm diode laser. The anti-Stokes processes vary from one photon to two photon, depending on the Cr<sup>3+</sup> content (x) in Ca<sub>3</sub>Ga<sub>2-x</sub>Cr<sub>x</sub>Ge<sub>3</sub>O<sub>12</sub>...
February 15, 2017: Optics Letters
Yejun Wang, Cade Capps, Waruna D Kulatilaka
Ultrashort-pulse (femtosecond-duration) two-photon laser-induced fluorescence (fs-TPLIF) of an inert gas tracer krypton (Kr) is investigated. A detailed spectroscopic study of fluorescence channels followed by the 5p<sup>'</sup>←←4p excitation of Kr at 204.1 nm is reported. The experimental line positions in the 750-840 nm emission region agree well with the NIST Atomic Spectra Database. The present work provides an accurate listing of relative line strengths in this spectral region. In the range of laser pulse energies investigated, a quadratic dependence was observed between the Kr-TPLIF signal and the laser pulse energy...
February 15, 2017: Optics Letters
Yu Shu, Tonghui Xu
Chronic stress is associated with occurrence of many mental disorders. Previous studies have shown that dendrites and spines of pyramidal neurons of the prefrontal cortex undergo drastic reorganization following chronic stress experience. So the prefrontal cortex is believed to play a key role in response of neural system to chronic stress. However, how stress induces dynamic structural changes in neural circuit of prefrontal cortex remains unknown. In the present study, we examined the effects of chronic social defeat stress on dendritic spine structural plasticity in the mouse frontal association (FrA) cortex in vivo using two-photon microscopy...
2017: Neural Plasticity
Yun Ma, Shujuan Liu, Huiran Yang, Yi Zeng, Pengfei She, Nianyong Zhu, Cheuk-Lam Ho, Qiang Zhao, Wei Huang, Wai-Yeung Wong
It is well-known that the variation of noncovalent interactions of luminophores, such as π-π interaction, metal-to-metal interaction, and hydrogen-bonding interaction, can regulate their emission colors. Electrostatic interaction is also an important noncovalent interaction. However, very few examples of luminescence color tuning induced by electrostatic interaction were reported. Herein, a series of Zn(II)-bis(terpyridine) complexes (Zn-AcO, Zn-BF4, Zn-ClO4, and Zn-PF6) containing different anionic counterions were reported, which exhibit counterion-dependent emission colors from green-yellow to orange-red (549 to 622 nm) in CH2Cl2 solution...
February 14, 2017: Inorganic Chemistry
Siyu Lu, Laizhi Sui, Junjun Liu, Shoujun Zhu, Anmin Chen, Mingxing Jin, Bai Yang
A facile, high-output strategy is developed for fabricating near-infrared-emissive polymer-carbon nanodots (PCNDs). The PCNDs emit at a wavelength of 710 nm with a QY of 26.28%, which is promising for deep biological imaging and luminescent devices. Moreover, the PCNDs possess two-photon fluorescence and. In vivo bioimaging and red light emitting diodes based on these PCNDs are demonstrated.
February 13, 2017: Advanced Materials
Baocun Zhu, Ping Li, Wei Shu, Xin Wang, Caiyun Liu, Yue Wang, Zuokai Wang, Yawei Wang, Bo Tang
Hypochlorous acid (HOCl) acts as a weak acid distributed mainly in acidic organelle lysosomes of phagocytes and plays a crucial role in the immune defense. The elaborate interrelation between the variations of HOCl levels in lysosomes and different physiological and pathological processes remains unclear. Thus, the accurate determination of lysosomal HOCl in living cells and in vivo is very important. Because of extremely low concentration and difficulty in distinguishing HOCl from OCl(-) under the physiological environment, it is still a great challenge to specifically monitor the intracellular intrinsic HOCl levels without exogenous stimulation, which impedes an exact understanding of its biological roles...
December 20, 2016: Analytical Chemistry
Wanying Li, Bingqing Fang, Ming Jin, Yang Tian
Zinc ion (Zn(2+)) not only plays an important function in the structural, catalytic, transcription, and regulatory of proteins, but is also an essential ionic signal to regulate brain neurotransmitters pass process. In this work, we designed and synthesized an intramolecular charge transfer-based ratiometric two-photon fluorescence probe, P-Zn, for imaging and biosensing of Zn(2+) in live cell, hippocampal tissue, and zebrafish. The developed probe demonstrated high two-photon absorption cross section (δ) of 516 ± 77 GM, which increased to 958 ± 144 GM after the probe was coordinated with Zn(2+)...
February 7, 2017: Analytical Chemistry
Mahdi Karimi, Parham Sahandi Zangabad, Soodeh Baghaee-Ravari, Mahdi Ghazizadeh, Hamed Mirshekari, Michael R Hamblin
Nanotechnology has begun to play a remarkable role in various fields of science and technology. In biomedical applications, nanoparticles have opened new horizons, especially for biosensing, targeted delivery of therapeutics, etc. Among drug delivery systems (DDSs), smart nanocarriers that can respond to specific stimuli in their local environment represent a growing field. Nanoplatforms that can be activated by an external application of light, can be used for a wide variety of photo-activated therapies, (especially light-triggered DDSs) relying on photo-isomerization, photo-crosslinking/uncrosslinking, photo-reduction, etc...
February 13, 2017: Journal of the American Chemical Society
Xuefeng Shi, Jad Barchini, Hector Acaron Ledesma, David Koren, Yanjiao Jin, Xiaorong Liu, Wei Wei, Jianhua Cang
Detecting visual features in the environment, such as motion direction, is crucial for survival. The circuit mechanisms that give rise to direction selectivity in a major visual center, the superior colliculus (SC), are entirely unknown. We optogenetically isolate the retinal inputs that individual direction-selective SC neurons receive and find that they are already selective as a result of precisely converging inputs from similarly tuned retinal ganglion cells. The direction-selective retinal input is linearly amplified by intracollicular circuits without changing its preferred direction or level of selectivity...
February 13, 2017: Nature Neuroscience
Dipankar Mondal, Debabrata Goswami
Multiphoton absorbing dye-coated trapped spherical bead at the focal plane of femtosecond optical tweezers shows nonlinear optical (NLO) phenomena. One such NLO process of two-photon fluorescence (TPF) has been used for the background-free imaging of a femtosecond laser-trapping event. Due to the high peak powers of femtosecond laser pulses with low average powers, it is possible to not only trap single nanospheres, but encourage optically directed self-assembly. The TPF signatures of trapped particles show evidence of such a directed self-assembly process which, in turn, can provide information about the structural dynamics during the process of cluster formation...
October 7, 2016: Methods and Applications in Fluorescence
Pamela T Wong, Edward W Roberts, Shengzhuang Tang, Jhindan Mukherjee, Jayme Cannon, Alyssa J Nip, Kaitlin Corbin, Matthew F Krummel, Seok Ki Choi
The use of coumarin caged molecules has been well documented in numerous photocaging applications including for the spatiotemporal control of Cre-estrogen receptor (Cre-ERT2) recombinase activity. In this article, we report that 4-hydroxytamoxifen (4OHT) caged with coumarin via a conventional ether linkage led to an unexpected photo-Claisen rearrangement which significantly competed with the release of free 4OHT. The basis for this unwanted reaction appears to be related to the coumarin structure and its radical-based mechanism of uncaging as it did not occur in ortho-nitrobenzyl (ONB) caged 4OHT that was otherwise linked in the same manner...
February 13, 2017: ACS Chemical Biology
Xuan Liang, Magdalene Michael, Guillermo A Gomez
The cortical actomyosin cytoskeleton is found in all non-muscle cells where a key function is to control mechanical force (Salbreux et al., 2012). When coupled to E-cadherin cell-cell adhesion, cortical actomyosin generates junctional tension that influences many aspects of tissue function, organization and morphogenesis (Lecuit and Yap, 2015). Uncovering the molecular mechanisms underlying the generation of junctional tension requires tools for measuring it in live cells with a high spatio-temporal resolution...
December 20, 2016: Bio-protocol
Mehmet F Keleş, Mark A Frye
Many animals rely on vision to detect objects such as conspecifics, predators, and prey. Hypercomplex cells found in feline cortex and small target motion detectors found in dragonfly and hoverfly optic lobes demonstrate robust tuning for small objects, with weak or no response to larger objects or movement of the visual panorama [1-3]. However, the relationship among anatomical, molecular, and functional properties of object detection circuitry is not understood. Here we characterize a specialized object detector in Drosophila, the lobula columnar neuron LC11 [4]...
January 30, 2017: Current Biology: CB
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