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Mehran Kianinia, Carlo Bradac, Bernd Sontheimer, Fan Wang, Toan Trong Tran, Minh Nguyen, Sejeong Kim, Zai-Quan Xu, Dayong Jin, Andreas W Schell, Charlene J Lobo, Igor Aharonovich, Milos Toth
Layered van der Waals materials are emerging as compelling two-dimensional platforms for nanophotonics, polaritonics, valleytronics and spintronics, and have the potential to transform applications in sensing, imaging and quantum information processing. Among these, hexagonal boron nitride (hBN) is known to host ultra-bright, room-temperature quantum emitters, whose nature is yet to be fully understood. Here we present a set of measurements that give unique insight into the photophysical properties and level structure of hBN quantum emitters...
February 28, 2018: Nature Communications
Diego Grassi, Shannon Howard, Minghai Zhou, Natalia Diaz-Perez, Nicolai T Urban, Debbie Guerrero-Given, Naomi Kamasawa, Laura A Volpicelli-Daley, Philip LoGrasso, Corinne Ida Lasmézas
Exposure of cultured primary neurons to preformed α-synuclein fibrils (PFFs) leads to the recruitment of endogenous α-synuclein and its templated conversion into fibrillar phosphorylated α-synuclein (pα-synF) aggregates resembling those involved in Parkinson's disease (PD) pathogenesis. Pα-synF was described previously as inclusions morphologically similar to Lewy bodies and Lewy neurites in PD patients. We discovered the existence of a conformationally distinct, nonfibrillar, phosphorylated α-syn species that we named "pα-syn*...
February 27, 2018: Proceedings of the National Academy of Sciences of the United States of America
Rifka Vlijm, Xue Li, Marko Panic, Diana Rüthnick, Shoji Hata, Frank Herrmannsdörfer, Thomas Kuner, Mike Heilemann, Johann Engelhardt, Stefan W Hell, Elmar Schiebel
The centrosome linker proteins C-Nap1, rootletin, and CEP68 connect the two centrosomes of a cell during interphase into one microtubule-organizing center. This coupling is important for cell migration, cilia formation, and timing of mitotic spindle formation. Very little is known about the structure of the centrosome linker. Here, we used stimulated emission depletion (STED) microscopy to show that each C-Nap1 ring at the proximal end of the two centrioles organizes a rootletin ring and, in addition, multiple rootletin/CEP68 fibers...
February 20, 2018: Proceedings of the National Academy of Sciences of the United States of America
S Roy Chowdhury, Jin Cao, Yufan He, H Peter Lu
Manipulating protein conformations for exploring protein structure-function relationship has shown a great promise. Although protein conformational changes under pulling force manipulation have been extensively studied, protein conformation changes under a compressive force have not been explored quantitatively. The latter is even more biologically significant and relevant in revealing the protein functions in living cells, associated with protein crowdedness, distribution fluctuations, and cell osmotic stress...
February 20, 2018: ACS Nano
Thibault Lagache, Alexandre Grassart, Stéphane Dallongeville, Orestis Faklaris, Nathalie Sauvonnet, Alexandre Dufour, Lydia Danglot, Jean-Christophe Olivo-Marin
Elucidating protein functions and molecular organisation requires to localise precisely single or aggregated molecules and analyse their spatial distributions. We develop a statistical method SODA (Statistical Object Distance Analysis) that uses either micro- or nanoscopy to significantly improve on standard co-localisation techniques. Our method considers cellular geometry and densities of molecules to provide statistical maps of isolated and associated (coupled) molecules. We use SODA with three-colour structured-illumination microscopy (SIM) images of hippocampal neurons, and statistically characterise spatial organisation of thousands of synapses...
February 15, 2018: Nature Communications
Anna M Chizhik, Carina Wollnik, Daja Ruhlandt, Narain Karedla, Alexey I Chizhik, Lara Hauke, Dirk Hähnel, Ingo Gregor, Jörg Enderlein, Florian Rehfeldt
We report a novel method, dual color axial nanometric localization by Metal Induced Energy Transfer (dcMIET), and combine it with Förster Resonant Energy Transfer (FRET) for resolving structural details in cells on the molecular level. We demonstrate the capability of this method on cytoskeletal elements and adhesions in human mesenchymal stem cells (hMSCs). Our approach is based on Fluorescence-Lifetime-Imaging Microscopy (FLIM), and allows for precise determination of the 3D architecture of stress fibers anchoring at focal adhesions, thus yielding crucial information to understand cell-matrix mechanics...
February 14, 2018: Molecular Biology of the Cell
Carola Gregor, Sven C Sidenstein, Martin Andresen, Steffen J Sahl, Johann G Danzl, Stefan W Hell
The reversibly switchable fluorescent proteins (RSFPs) commonly used for RESOLFT nanoscopy have been developed from fluorescent proteins of the GFP superfamily. These proteins are bright, but exhibit several drawbacks such as relatively large size, oxygen-dependence, sensitivity to low pH, and limited switching speed. Therefore, RSFPs from other origins with improved properties need to be explored. Here, we report the development of two RSFPs based on the LOV domain of the photoreceptor protein YtvA from Bacillus subtilis...
February 9, 2018: Scientific Reports
Xiaohe Tian, Hui Wang, Qiong Zhang, Mingzhu Zhang, Yingzhong Zhu, Yan Chen, Jieying Wu, Yupeng Tian
Probe for dual-site target distinct subcellular compartments from cytosol and nucleus is an attractive approach, however, which was scarcely reported. Herein, a series of small-molecular thiophene pyridium salt derivatives (MitoNuc1-4) possessing water-soluble, high quantum yield and two-photon activity were rationally designed, and their structures were crystallographic confirmed. Systematic photophysical and biological imaging property investigations were carried out for them. It was found that MitoNuc1-4 exhibit two-photon absorption properties in the near infrared region, and MitoNuc1 has membrane permeability and cationic nature, rendering it to be double labelling of mitochondria and nucleolus in living cells with superb photo-stability and non-invasiveness...
May 30, 2018: Analytica Chimica Acta
Waja Wegner, Alexander C Mott, Seth G N Grant, Heinz Steffens, Katrin I Willig
The post-synaptic density (PSD) is an electron dense region consisting of ~1000 proteins, found at the postsynaptic membrane of excitatory synapses, which varies in size depending upon synaptic strength. PSD95 is an abundant scaffolding protein in the PSD and assembles a family of supercomplexes comprised of neurotransmitter receptors, ion channels, as well as signalling and structural proteins. We use superresolution STED (STimulated Emission Depletion) nanoscopy to determine the size and shape of PSD95 in the anaesthetised mouse visual cortex...
January 9, 2018: Scientific Reports
Michael Abadier, Akula Bala Pramod, Sara McArdle, Alex Marki, Zhichao Fan, Edgar Gutierrez, Alex Groisman, Klaus Ley
The adaptive immune response involves T cell differentiation and migration to sites of inflammation. T cell trafficking is initiated by rolling on inflamed endothelium. Tethers and slings, discovered in neutrophils, facilitate cell rolling at high shear stress. Here, we demonstrate that the ability to form tethers and slings during rolling is highly inducible in T helper 1 (Th1), Th17, and regulatory T (Treg) cells but less in Th2 cells. In vivo, endogenous Treg cells rolled stably in cremaster venules at physiological shear stress...
December 26, 2017: Cell Reports
Roderick P Tas, Anaël Chazeau, Bas M C Cloin, Maaike L A Lambers, Casper C Hoogenraad, Lukas C Kapitein
Microtubules are essential for polarized transport in neurons, but how their organization guides motor proteins to axons or dendrites is unclear. Because different motors recognize distinct microtubule properties, we used optical nanoscopy to examine the relationship between microtubule orientations, stability, and modifications. Nanometric tracking of motors to super-resolve microtubules and determine their polarity revealed that in dendrites, stable and acetylated microtubules are mostly oriented minus-end out, while dynamic and tyrosinated microtubules are oriented oppositely...
December 20, 2017: Neuron
Federico M Barabas, Luciano A Masullo, Martín D Bordenave, Sebastián A Giusti, Nicolás Unsain, Damián Refojo, Alfredo Cáceres, Fernando D Stefani
Fluorescence nanoscopy imaging permits the observation of periodic supramolecular protein structures in their natural environment, as well as the unveiling of previously unknown protein periodic structures. Deciphering the biological functions of such protein nanostructures requires systematic and quantitative analysis of large number of images under different experimental conditions and specific stimuli. Here we present a method and an open source software for the automated quantification of protein periodic structures in super-resolved images...
November 22, 2017: Scientific Reports
Xuzhu Zhang, Evangelos Sisamakis, Krzysztof Sozanski, Robert Holyst
Equilibrium and rate constants are key descriptors of complex-formation processes in a variety of chemical and biological reactions. However, these parameters are difficult to quantify, especially in the locally confined, heterogeneous, and dynamically changing living matter. Herein, we address this challenge by combining stimulated emission depletion (STED) nanoscopy with fluorescence correlation spectroscopy (FCS). STED reduces the length-scale of observation to tens of nanometres (2D)/attoliters (3D) and the time-scale to microseconds, with direct, gradual control...
December 7, 2017: Journal of Physical Chemistry Letters
Jan Philip Kraack
Ultrafast, multi-dimensional infrared (IR) spectroscopy has been advanced in recent years to a versatile analytical tool with a broad range of applications to elucidate molecular structure on ultrafast timescales, and it can be used for samples in a many different environments. Following a short and general introduction on the benefits of 2D IR spectroscopy, the first part of this chapter contains a brief discussion on basic descriptions and conceptual considerations of 2D IR spectroscopy. Outstanding classical applications of 2D IR are used afterwards to highlight the strengths and basic applicability of the method...
October 25, 2017: Topics in Current Chemistry (Journal)
Sofia D'Abrantes, Sarah Gratton, Pamela Reynolds, Verena Kriechbaumer, Joseph McKenna, Stephen Barnard, Dave Clarke, Stanley W Botchway
Genomic deoxyribonucleic acid (DNA) is continuously being damaged by endogenous processes such as metabolism or by exogenous events such as radiation. The specific phosphorylation of histone H2AX on serine residue 139, described as γ-H2AX, is an excellent indicator or marker of DNA double-strand breaks (DSBs). The yield of γ-H2AX (foci) is shown to have some correlation with the dose of radiation or other DSB-causing agents. However, there is some discrepancy in the DNA DSB foci yield among imaging and other methods such as gel electrophoresis...
October 20, 2017: Radiation Research
Qiuqiang Zhan, Haichun Liu, Baoju Wang, Qiusheng Wu, Rui Pu, Chao Zhou, Bingru Huang, Xingyun Peng, Hans Ågren, Sailing He
Stimulated emission depletion microscopy provides a powerful sub-diffraction imaging modality for life science studies. Conventionally, stimulated emission depletion requires a relatively high light intensity to obtain an adequate depletion efficiency through only light-matter interaction. Here we show efficient emission depletion for a class of lanthanide-doped upconversion nanoparticles with the assistance of interionic cross relaxation, which significantly lowers the laser intensity requirements of optical depletion...
October 20, 2017: Nature Communications
Stefan Mastel, Mark B Lundeberg, Pablo Alonso-González, Yuanda Gao, Kenji Watanabe, Takashi Taniguchi, James Hone, Frank H L Koppens, Alexey Y Nikitin, Rainer Hillenbrand
We developed THz-resonant scanning probe tips, yielding strongly enhanced and nanoscale confined THz near fields at their tip apex. The tips with length in the order of the THz wavelength (λ = 96.5 μm) were fabricated by focused ion beam (FIB) machining and attached to standard atomic force microscopy (AFM) cantilevers. Measurements of the near-field intensity at the very tip apex (25 nm radius) as a function of tip length, via graphene-based (thermoelectric) near-field detection, indicate their first and second order geometrical antenna resonances for tip length of 33 and 78 μm, respectively...
October 30, 2017: Nano Letters
Dongyu Li, Wei Qin, Bin Xu, Jun Qian, Ben Zhong Tang
Stimulated emission depletion (STED) nanoscopy is a typical super-resolution imaging technique that has become a powerful tool for visualizing intracellular structures on the nanometer scale. Aggregation-induced emission (AIE) luminogens are ideal fluorescent agents for bioimaging. Herein, long-term super-resolution fluorescence imaging of cancer cells, based on STED nanoscopy assisted by AIE nanoparticles (NPs) is realized. 2,3-Bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TTF), a typical AIE luminogen, is doped into colloidal mesoporous silica to form fluorescent NPs...
October 4, 2017: Advanced Materials
Ben E Urban, Lei Xiao, Biqin Dong, Siyu Chen, Yevgenia Kozorovitskiy, Hao F Zhang
Visualizing fine neuronal structures deep inside strong light-scattering brain tissue remains a challenge in neuroscience. Recent nanoscopy techniques have reached the necessary resolution, but often suffer from limited imaging depth, long imaging time, or high light fluence requirements. Here, we present two-photon Super-resolution Patterned Excitation Reconstruction (2P-SuPER) microscopy for three-dimensional imaging of dendritic spine dynamics at a maximum demonstrated imaging depth of 130 μm in living brain tissue with approximately 100 nm spatial resolution...
October 4, 2017: Journal of Biophotonics
Ashish Bhattarai, Alan G Joly, Wayne P Hess, Patrick Z El-Khoury
Tip-enhanced Raman scattering (TERS) can be used to image plasmon-enhanced local electric fields on the nanoscale. This is illustrated through ambient TERS measurements recorded using silver atomic force microscope tips coated with 4-mercaptobenzonitrile molecules and used to image step edges on an Au(111) surface. The observed two-dimensional TERS images uniquely map electric fields localized at Au(111) step edges following 671 nm excitation. We establish that our measurements are not only sensitive to spatial variations in the enhanced electric fields but also to their vector components...
October 5, 2017: Nano Letters
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