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Daniel Jaeger, Christian Pilger, Henning Hachmeister, Elina Oberländer, Robin Wördenweber, Julian Wichmann, Jan H Mussgnug, Thomas Huser, Olaf Kruse
Oleaginous photosynthetic microalgae hold great promise as non-food feedstocks for the sustainable production of bio-commodities. The algal lipid quality can be analysed by Raman micro-spectroscopy, and the lipid content can be imaged in vivo in a label-free and non-destructive manner by coherent anti-Stokes Raman scattering (CARS) microscopy. In this study, both techniques were applied to the oleaginous microalga Monoraphidium neglectum, a biotechnologically promising microalga resistant to commonly applied lipid staining techniques...
October 21, 2016: Scientific Reports
Aram Hong, Heeseon Jang, Changseop Jeong, Myoung Choul Choi, Jiyoung Heo, Nam Joon Kim
We obtained resonant two-photon ionization circular dichroism (R2PICD) spectra of jet-cooled phenylalanine (Phe) and its hydrated clusters (Phe(H2O)n, n=1-2) near the origin band of the S0-S1 transition. The R2PICD spectra of Phe exhibit well-resolved CD bands of six different conformers present in the jet, which vary in sign and magnitude depending on their conformations. We revised the previous structural assignments of the Phe conformers based on the comparison between the experimental and theoretical CD signs, infrared spectra, and rotational band contours...
October 21, 2016: Journal of Physical Chemistry Letters
Hong Sheng Quah, Li Ting Ng, Bruno Donnadieu, Geok Kheng Tan, Jagadese J Vittal
Five lanthanide MOFs with pcu topology have been exfoliated into nanoplatelets of two-dimensional structures via sonication in the dimethylacetamide solvent. These nanosheets are fluorescent under two-photon excitation dominated by the ligand, indicating energy upconversion ability.
October 20, 2016: Inorganic Chemistry
Markus Seeger, Angelos Karlas, Dominik Soliman, Jaroslav Pelisek, Vasilis Ntziachristos
Carotid artery atherosclerosis is a main cause of stroke. Understanding atherosclerosis biology is critical in the development of targeted prevention and treatment strategies. Consequently, there is demand for advanced tools investigating atheroma pathology. We consider hybrid optoacoustic and multiphoton microscopy for the integrated and complementary interrogation of plaque tissue constituents and their mutual interactions. Herein, we visualize human carotid plaque using a hybrid multimodal imaging system that combines optical resolution optoacoustic (photoacoustic) microscopy, second and third harmonic generation microscopy, and two-photon excitation fluorescence microscopy...
September 2016: Photoacoustics
Verónica Pérez-Schuster, Anirudh Kulkarni, Morgane Nouvian, Sebastián A Romano, Konstantinos Lygdas, Adrien Jouary, Mario Dippopa, Thomas Pietri, Mathieu Haudrechy, Virginie Candat, Jonathan Boulanger-Weill, Vincent Hakim, Germán Sumbre
Following moving visual stimuli (conditioning stimuli, CS), many organisms perceive, in the absence of physical stimuli, illusory motion in the opposite direction. This phenomenon is known as the motion aftereffect (MAE). Here, we use MAE as a tool to study the neuronal basis of visual motion perception in zebrafish larvae. Using zebrafish eye movements as an indicator of visual motion perception, we find that larvae perceive MAE. Blocking eye movements using optogenetics during CS presentation did not affect MAE, but tectal ablation significantly weakened it...
October 18, 2016: Cell Reports
Wen-Shuo Kuo, Chia-Yuan Chang, Hua-Han Chen, Chih-Li Lilian Hsu, Jiu-Yao Wang, Hui-Fang Kao, Lawrence Chao-Shan Chou, Yi-Chun Chen, Shean-Jen Chen, Wen-Tsan Chang, Shih-Wen Tseng, Ping-Ching Wu, Ying-Chih Pu
A graphene quantum dot (GQD) used as the photosensitizer with high two-photon absorption in the near-infrared region, a large absolute cross section of two-photon excitation (TPE), strong two-photon luminescence and impressive two-photon stability could be used for dual modality two-photon photodynamic therapy (PDT) and two-photon bioimaging with an ultrashot pulse laser (or defined as TPE). In this study, a GQD efficiently generated reactive oxygen species coupled with TPE, which highly increased the effective PDT ability of both gram-positive and -negative bacteria, with ultra-low energy and an extremely short photoexcitation time generated by TPE...
October 18, 2016: ACS Applied Materials & Interfaces
Yonglei Li, Yangfu Fang, Jiao Wang, Lu Wang, Shiwei Tang, Chunping Jiang, Lirong Zheng, Yongfeng Mei
Miniaturization of functional devices and systems demands new design and fabrication approaches for lab-on-a-chip application and optical integrative systems. By using a direct laser writing (DLW) technique based on two-photon polymerization (TPP), a highly integrative optofluidic refractometer is fabricated and demonstrated based on tubular optical microcavities coupled with waveguides. Such tubular devices can support high quality factor (Q-factor) up to 3600 via fiber taper coupling. Microtubes with various diameters and wall thicknesses are constructed with optimized writing direction and conditions...
October 18, 2016: Lab on a Chip
Alexei Smolyaninov, Mu-Han Yang, Lin Pang, Yeshaiahu Fainman
A high-density array of plasmonic coaxial nanoantennas is used to enhance the two-photon absorption (TPA) process in a conventional silicon photodetector from a mode-locked 76 MHz Ti:sapphire laser over a spectral range from 1340 to 1550 nm. This enhanced TPA was used to generate an interferometric autocorrelation trace of a 150 fs laser pulse. Unlike second-harmonic generation, this technique does not require phase matching or a bulky crystal and can be used on a low-cost integrated silicon platform over a wide range of near-IR wavelengths compatible with modern commercial tunable femtosecond sources...
October 1, 2016: Optics Letters
K M Naga Srinivas Nadella, Hana Roš, Chiara Baragli, Victoria A Griffiths, George Konstantinou, Theo Koimtzis, Geoffrey J Evans, Paul A Kirkby, R Angus Silver
Understanding how neural circuits process information requires rapid measurements of activity from identified neurons distributed in 3D space. Here we describe an acousto-optic lens two-photon microscope that performs high-speed focusing and line scanning within a volume spanning hundreds of micrometers. We demonstrate its random-access functionality by selectively imaging cerebellar interneurons sparsely distributed in 3D space and by simultaneously recording from the soma, proximal and distal dendrites of neocortical pyramidal cells in awake behaving mice...
October 17, 2016: Nature Methods
Je-Hyung Kim, Christopher J K Richardson, Richard P Leavitt, Edo Waks
Interactions between solid-state quantum emitters and cavities are important for a broad range of applications in quantum communication, linear optical quantum computing, nonlinear photonics, and photonic quantum simulation. These applications often require combining many devices on a single chip with identical emission wavelengths in order to generate two-photon interference, the primary mechanism for achieving effective photon-photon interactions. Such integration remains extremely challenging due to inhomogeneous broadening and fabrication errors that randomize the resonant frequencies of both the emitters and cavities...
October 17, 2016: Nano Letters
Raf Donders, Kathleen Sanen, Rik Paesen, Eli Slenders, Wilfried Gyselaers, Piet Stinissen, Marcel Ameloot, Niels Hellings
In situ detection of MSCs remains difficult and warrants additional methods to aid with their characterization in vivo. Two-photon confocal laser scanning microscopy (TPM) and second harmonic generation (SHG) could fill this gap. Both techniques enable the detection of cells and extracellular structures, based on intrinsic properties of the specific tissue and intracellular molecules under optical irradiation. TPM imaging and SHG imaging have been used for label-free monitoring of stem cells differentiation, assessment of their behavior in biocompatible scaffolds, and even cell tracking in vivo...
2016: Stem Cells International
Sunggu Yang, Mariton D Santos, Cha-Min Tang, Jae Geun Kim, Sungchil Yang
Synaptic plasticity is a fundamental component of information processing in the brain. Presynaptic facilitation in response to repetitive stimuli, often referred to as paired-pulse facilitation (PPF), is a dominant form of short-term synaptic plasticity. Recently, an additional cellular mechanism for short-term facilitation, short-term postsynaptic plasticity (STPP), has been proposed. While a dendritic mechanism was described in hippocampus, its expression has not yet been demonstrated at the levels of the spine...
2016: Frontiers in Cellular Neuroscience
Luke McKenzie, Igor Sazanovich, Elizabeth Baggaley, Mickaële Bonneau, Véronique Guerchais, Gareth Williams, Julia Weinstein, Helen E Bryant
Photodynamic therapy (PDT) uses photosensitizers (PS) which only become cytotoxic upon light-irradiation. Transition metal complexes are highly promising PS due to long excited state lifetimes, and photostability. However, these complexes usually absorb higher-energy UV/Visible light, whilst the optimal tissue transparency is in the lower-energy NIR region. Two-photon excitation (TPE) can overcome this dichotomy, with simultaneous absorption of two lower-energy NIR-photons populating the same PS-active excited state as one higher-energy photon...
October 14, 2016: Chemistry: a European Journal
Idan Elbaz, David Zada, Adi Tovin, Tslil Braun, Tali Lerer-Goldshtein, Gordon Wang, Philippe Mourrain, Lior Appelbaum
Sleep is tightly regulated by the circadian clock and homeostatic mechanisms. Although the sleep/wake cycle is known to be associated with structural and physiological synaptic changes that benefit the brain, the function of sleep is still debated. The hypothalamic hypocretin/orexin (Hcrt) neurons regulate various functions including feeding, reward, sleep, and wake. Continuous imaging of single neuronal circuits in live animals is vital to understanding the role of sleep in regulating synaptic dynamics, and the transparency of the zebrafish model enables time-lapse imaging of single synapses during both day and night...
October 12, 2016: Molecular Neurobiology
Christian Chunzi Archer-Zhang, Warren B Foster, Ryan D Downey, Christopher L Arrasmith, David L Dickensheets
No abstract text is available yet for this article.
December 1, 2016: Journal of Biomedical Optics
Gary Razinskas, Deirdre Kilbane, Pascal Melchior, Peter Geisler, Enno Krauss, Stefan Mathias, Bert Hecht, Martin Aeschlimann
The design of noble-metal plasmonic devices and nanocircuitry requires a fundamental understanding and control of the interference of plasmonic modes. Here we report the first visualization of the propagation and interference of guided modes in a showcase plasmonic nanocircuit using normal-incidence nonlinear two-photon photoemission electron microscopy (PEEM). We demonstrate that in contrast to the commonly used grazing-incidence illumination scheme, normal-incidence PEEM provides a direct image of the structure's near-field intensity distribution due to the absence of beating patterns and despite the transverse character of the plasmonic modes...
October 10, 2016: Nano Letters
S Sanyal, A Painelli, S K Pati, F Terenziani, C Sissa
We present a theoretical investigation of small aggregates of quadrupolar (A-π-D-π-A or D-π-A-π-D) charge-transfer dyes, with attention focused on the role of intermolecular interactions in determining their optical properties. We tackle the theoretical issue by adopting essential-state models (ESMs), which describe an isolated molecule in terms of a minimal number of electronic states, corresponding to the resonance structures. ESMs quite naturally describe intermolecular interactions relaxing the dipolar approximation and accounting for molecular polarizabilities...
October 12, 2016: Physical Chemistry Chemical Physics: PCCP
Yun Hak Lee, Yonghe Tang, Peter Verwilst, Weiying Lin, Jong Seung Kim
A biotin appended formaldehyde sensor was found to specifically visualise both exogenous and endogenous levels of formaldehyde in biotin receptor positive cells over biotin negative cells by means of one- and two-photon excitation. The probe furthermore visualised endogenous levels of formaldehyde in tumour tissue slices up to 70 μm depth.
September 13, 2016: Chemical Communications: Chem Comm
Hong-Wen Liu, Shuai Xu, Peng Wang, Xiao-Xiao Hu, Jing Zhang, Lin Yuan, Xiao-Bing Zhang, Weihong Tan
A promising two-photon fluorescent probe MNAH for detecting (1)O2 during the PDT process in mitochondria was proposed for the first time. MNAH was successfully applied for two-photon imaging of (1)O2 in living cells and tissues during the PDT process with deep-tissue imaging depth. MNAH can be a powerful molecular tool for studying (1)O2 generation in mitochondria during the PDT process.
October 11, 2016: Chemical Communications: Chem Comm
N-H Nguyen, N Bogliotti, R Chennoufi, E Henry, P Tauc, E Salas, L J Roman, A Slama-Schwok, E Deprez, J Xie
A new series of photoactivable NADPH mimics bearing one or two O-carboxymethyl groups on the adenosine moiety have been readily synthesized using click chemistry. These compounds display interesting one- or two-photon absorption properties. Their fluorescence emission wavelength and quantum yields (Φ) are dependent on the solvent polarity, with a red-shift in a more polar environment (λmax,em = 460-467 nm, Φ > 0.53 in DMSO, and λmax,em = 475-491 nm, Φ < 0.17 in Tris). These compounds show good binding affinity towards the constitutive nNOS and eNOS, confirming for the first time that the carboxymethyl group can be used as a surrogate of phosphate...
October 12, 2016: Organic & Biomolecular Chemistry
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