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https://www.readbyqxmd.com/read/29166054/modeling-super-resolution-sers-using-a-t-matrix-method-to-elucidate-molecule-nanoparticle-coupling-and-the-origins-of-localization-errors
#1
Charles W Heaps, George C Schatz
A computational method to model diffraction-limited images from super-resolution surface-enhanced Raman scattering microscopy is introduced. Despite significant experimental progress in plasmon-based super-resolution imaging, theoretical predictions of the diffraction limited images remain a challenge. The method is used to calculate localization errors and image intensities for a single spherical gold nanoparticle-molecule system. The light scattering is calculated using a modification of generalized Mie (T-matrix) theory with a point dipole source and diffraction limited images are calculated using vectorial diffraction theory...
June 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166030/dissolution-and-characterization-of-boron-nitride-nanotubes-in-superacid
#2
Olga Kleinerman, Mohammed Adnan, Daniel M Marincel, Anson Wk Ma, E Amram Bengio, Cheol Park, Sang-Hyon Chu, Matteo Pasquali, Yeshayahu Talmon
Boron nitride nanotubes (BNNTs) are of interest for their unique combination of high tensile strength, high electrical resistivity, high neutron cross-section, and low reactivity. The fastest route to employing these properties in composites and macroscopic articles is through solution processing. However, dispersing BNNTs without functionalization or use of a surfactant is challenging. We show here by cryogenic transmission electron microscopy that BNNTs spontaneously dissolve in chlorosulfonic acid as disentangled individual molecules...
November 22, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29165899/quantitative-performance-evaluation-of-a-back-illuminated-scmos-camera-with-95-qe-for-super-resolution-localization-microscopy
#3
Yujie Wang, Lingxi Zhao, Zhe Hu, Yina Wang, Zeyu Zhao, Luchang Li, Zhen-Li Huang
Scientific Complementary Metal Oxide Semiconductor (sCMOS) cameras were introduced into the market in 2009 and are now becoming a major type of commercial cameras for low-light imaging. sCMOS cameras provide simultaneously low read noise, high readout speed, and large pixel array; however, the relatively low quantum efficiency (QE) of sCMOS cameras has been a major limitation for its application in single molecule imaging, especially super-resolution localization microscopy which requires high detection sensitivity...
November 22, 2017: Cytometry. Part A: the Journal of the International Society for Analytical Cytology
https://www.readbyqxmd.com/read/29163610/single-molecule-fluorescence-methods-to-study-plant-hormone-signal-transduction-pathways
#4
Song Song, Jian Chang, Chongjun Ma, Yan-Wen Tan
Plant-hormone-initiated signaling pathways are extremely vital for plant growth, differentiation, development, and adaptation to environmental stresses. Hormonal perception by receptors induces downstream signal transduction mechanisms that lead to plant responses. However, conventional techniques-such as genetics, biochemistry, and physiology methods-that are applied to elucidate these signaling pathways can only provide qualitative or ensemble-averaged quantitative results, and the intrinsic molecular mechanisms remain unclear...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/29163046/rim-binding-protein-2-promotes-a-large-number-of-cav1-3-ca-2-channels-and-contributes-to-fast-synaptic-vesicle-replenishment-at-hair-cell-active-zones
#5
Stefanie Krinner, Tanvi Butola, SangYong Jung, Carolin Wichmann, Tobias Moser
Ribbon synapses of inner hair cells (IHCs) mediate high rates of synchronous exocytosis to indefatigably track the stimulating sound with sub-millisecond precision. The sophisticated molecular machinery of the inner hair cell active zone realizes this impressive performance by enabling a large number of synaptic voltage-gated CaV1.3 Ca(2+)-channels, their tight coupling to synaptic vesicles (SVs) and fast replenishment of fusion competent SVs. Here we studied the role of RIM-binding protein 2 (RIM-BP2)-a multidomain cytomatrix protein known to directly interact with Rab3 interacting molecules (RIMs), bassoon and CaV1...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/29162902/shear-stress-regulates-trpv4-channel-clustering-and-translocation-from-adherens-junctions-to-the-basal-membrane
#6
Sara Baratchi, Markus Knoerzer, Khashayar Khoshmanesh, Arnan Mitchell, Peter McIntyre
Localized Ca(2+) influx via TRPV4 on the surface of endothelial cells greatly influences endothelial adaptation to blood flow, but how mechanical stress from blood flow controls TRPV4 integration into this physiological function is not fully understood. Here, we studied the spatial organization of TRPV4 and its relationship to the adherens junction component β-catenin using single- and dual-color direct stochastic optical reconstruction microscopy (dSTORM). In non-stimulated endothelial cells, TRPV4 is clustered in small protein islands, as is β-catenin...
November 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29162870/hdl-particles-incorporate-into-lipid-bilayers-a-combined-afm-and-single-molecule-fluorescence-microscopy-study
#7
Birgit Plochberger, Clemens Röhrl, Johannes Preiner, Christian Rankl, Mario Brameshuber, Josef Madl, Robert Bittman, Robert Ros, Erdinc Sezgin, Christian Eggeling, Peter Hinterdorfer, Herbert Stangl, Gerhard J Schütz
The process, how lipids are removed from the circulation and transferred from high density lipoprotein (HDL) - a main carrier of cholesterol in the blood stream - to cells, is highly complex. HDL particles are captured from the blood stream by the scavenger receptor, class B, type I (SR-BI), the so-called HDL receptor. The details in subsequent lipid-transfer process, however, have not yet been completely understood. The transfer has been proposed to occur directly at the cell surface across an unstirred water layer, via a hydrophobic channel in the receptor, or after HDL endocytosis...
November 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29161995/carbon-capture-from-natural-gas-using-multi-walled-cnts-based-mixed-matrix-membranes
#8
Abid Hussain, Sarah Farrukh, Arshad Hussain, Muhammad Ayoub
Most of the pure polymers and their blends, utilized in carbon capture membranes are costly but cellulose acetate (CA) being inexpensive, is a lucrative choice. In this research polymeric and mixed matrix membranes (MMMs) have been fabricated to carbon capture from Natural gas. Polyethylene glycol (PEG) has been utilized in the fabrication of these membranes to modify the chain flexibility of polymers which in turn amends the permeability of different gases through these polymers. Whereas multi-wall carbon nanotubes (MWCNTs) provide mechanical strength, thermal stability, an extra free path for CO2 molecules and augment CO2/CH4 selectivity...
November 22, 2017: Environmental Technology
https://www.readbyqxmd.com/read/29160067/molecular-tension-probes-for-imaging-forces-at-the-cell-surface
#9
Yang Liu, Kornelia Galior, Victor Pui-Yan Ma, Khalid Salaita
Mechanical forces are essential for a variety of biological processes ranging from transcription and translation to cell adhesion, migration, and differentiation. Through the activation of mechanosensitive signaling pathways, cells sense and respond to physical stimuli from the surrounding environment, a process widely known as mechanotransduction. At the cell membrane, many signaling receptors, such as integrins, cadherins and T- or B-cell receptors, bind to their ligands on the surface of adjacent cells or the extracellular matrix (ECM) to mediate mechanotransduction...
November 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29159501/a-fundamental-study-of-photoluminescence-modulation-from-dna-wrapped-single-walled-carbon-nanotubes
#10
Shusuke Oura, Masahiro Ito, Yoshikazu Homma, Kazuo Umemura
In this study, we investigated the interaction of base sequence-assigned single-stranded DNA (ssDNA) molecules with the surfaces of single-walled carbon nanotube (SWNT)-thymine (T30)/cytosine (C30) hybrids (T30/C30-SWNT), by measuring the modulation of near-infrared (NIR) photoluminescence (PL). Significant PL shifts were observed when T30/C30-SWNTs were reacted with 30-mers of adenine (A30)/guanine (G30). In contrast, when non-complementary ssDNA was used, no significant energy shift was observed in the PL modulation except when T30-SWNTs were reacted with G30...
November 20, 2017: European Biophysics Journal: EBJ
https://www.readbyqxmd.com/read/29157577/single-molecule-imaging-of-gpcr-interactions
#11
REVIEW
Davide Calebiro, Titiwat Sungkaworn
G protein-coupled receptors (GPCRs) constitute the largest family of membrane receptors and are of great interest as pharmacological targets. Although the occurrence of GPCR signaling nanodomains has long been hypothesized based on indirect evidence, this and other fundamental aspects of GPCR signaling have been difficult to prove. The advent of single-molecule microscopy methods, which allow direct visualization of individual membrane proteins with unprecedented spatiotemporal resolution, provides unique opportunities to address several of these open questions...
November 17, 2017: Trends in Pharmacological Sciences
https://www.readbyqxmd.com/read/29153085/an-ultra-sensitive-fluorescent-turn-on-biosensor-for-glutathione-and-its-application-in-living-cells
#12
Wei Wang, Xiaoshan Hou, Xin Li, Chen Chen, Xiliang Luo
In this work, an effective controlled-release biosensor based on Au nanocages (AuNCs) capped with disulfide-containing DNA molecular gates was developed for ultra-sensitive and highly selective detection of glutathione (GSH). Oligonucleotides containing the S-S bonds were assembled on the surface of the AuNCs by means of electrostatic interactions in order to inhibit the release of fluorescent molecules such as Rhodamine B (RhB) loaded by AuNCs. In the presence of GSH, due to the specific cleavage of S-S bonds in disulfide-containing single-stranded DNAs (ssDNAs) as well as their subsequent departure from the surface of AuNCs, the pores could be opened, and then the dye molecules would be released from AuNCs...
January 15, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29148737/site-specific-one-to-one-click-coupling-of-single-proteins-to-individual-carbon-nanotubes-a-single-molecule-approach
#13
Mark Freeley, Harley Worthy, Rochelle Ahmed, Ben Bowen, Daniel Watkins, John Emyr Macdonald, Ming Zheng, Darran Dafydd Jones, Matteo Palma
We report the site-specific coupling of single proteins to individual carbon nanotubes (CNTs) in solution and with single-molecule control. Using an orthogonal Click reaction, Green Fluorescent Protein (GFP) was engineered to contain a genetically encoded azide group and then bound to CNT ends in different configurations: in close proximity or at longer distances from the GFP's functional centre. Atomic force microscopy and fluorescence analysis in solution and on surfaces at the single-protein level confirmed the importance of bioengineering optimal protein attachment sites to achieve direct protein-nanotube communication and bridging...
November 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29148550/two-dimensional-2d-self-assembly-of-oligo-phenylene-ethynylene-molecules-and-their-triangular-platinum-ii-diimine-complexes-studied-using-stm
#14
Siqi Zhang, Yanfang Geng, Yuanpeng Fan, Wubiao Duan, Ke Deng, Dahui Zhao, Qingdao Zeng
In this investigation, the two-dimensional (2D) self-assembly nanostructures of a series of cyclic oligo(phenylene-ethynylene) (OPE) molecules (L1, L2-6 and L2-12) at the 1-phenyloctane/highly oriented pyrolytic graphite (HOPG) interface were thoroughly studied using scanning tunneling microscopy (STM). Comparative STM studies with their triangular Pt(ii) diimine complexes (C1, C2-6 and C2-12) were also carried out. Based on careful measurements on single molecule level STM images and density functional theory (DFT) calculations, the formation mechanisms of the nanoarrays formed were revealed...
November 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29147547/multi-dimensional-charge-transport-in-supramolecular-helical-foldamer-assemblies
#15
Alejandro Méndez-Ardoy, Nagula Markandeya, Xuesong Li, Yu-Tang Tsai, Gilles Pecastaings, Thierry Buffeteau, Victor Maurizot, Luca Muccioli, Frédéric Castet, Ivan Huc, Dario M Bassani
Aromatic foldamers are bioinspired architectures whose potential use in materials remains largely unexplored. Here we report our investigation of vertical and horizontal charge transport over long distances in helical oligo-quinolinecarboxamide foldamers organized as single monolayers on Au or SiO2. Conductive atomic force microscopy showed that vertical conductivity is efficient and that it displays a low attenuation with foldamer length (0.06 Å(-1)). In contrast, horizontal charge transport is found to be negligible, demonstrating the strong anisotropy of foldamer monolayers...
October 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29147545/protein-labeling-for-live-cell-fluorescence-microscopy-with-a-highly-photostable-renewable-signal
#16
Nina G Bozhanova, Mikhail S Baranov, Natalia V Klementieva, Karen S Sarkisyan, Alexey S Gavrikov, Ilia V Yampolsky, Elena V Zagaynova, Sergey A Lukyanov, Konstantin A Lukyanov, Alexander S Mishin
We present protein-PAINT - the implementation of the general principles of PAINT (Point Accumulation for Imaging in Nanoscale Topography) for live-cell protein labeling. Our method employs the specific binding of cell-permeable fluorogenic dyes to genetically encoded protein tags. We engineered three mutants of the bacterial lipocalin Blc that possess different affinities to a fluorogenic dye and exhibit a strong increase in fluorescence intensity upon binding. This allows for rapid labeling and washout of intracellular targets on a time scale from seconds to a few minutes...
October 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29145649/single-molecule-compaction-of-megabase-long-chromatin-molecules-by-multivalent-cations
#17
Anatoly Zinchenko, Nikolay V Berezhnoy, Sai Wang, William M Rosencrans, Nikolay Korolev, Johan R C van der Maarel, Lars Nordenskiöld
To gain insight into the conformational properties and compaction of megabase-long chromatin molecules, we reconstituted chromatin from T4 phage DNA (165 kb) and recombinant human histone octamers (HO). The unimolecular compaction, induced by divalent Mg2+ or tetravalent spermine4+ cations, studied by single-molecule fluorescence microscopy (FM) and dynamic light scattering (DLS) techniques, resulted in the formation of 250-400 nm chromatin condensates. The compaction on this scale of DNA size is comparable to that of chromatin topologically associated domains (TAD) in vivo...
November 14, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/29141403/lipogels-for-encapsulation-of-hydrophilic-proteins-and-hydrophobic-small-molecules
#18
Celia C Homyak, Ann Fernandez, Mollie A Touve, Bo Zhao, Francesca Anson, Jeanne A Hardy, Richard W Vachet, Nathan C Gianneschi, Jennifer L Ross, S Thayumanavan
Lipid-polymer hybrid materials have the potential to exhibit enhanced stability and loading capabilities in comparison to parent liposome or polymer materials. However, complexities lie in formulating and characterizing such complex nanomaterials. Here we describe a lipid-coated polymer gel (lipogel) formulated using a one-pot methodology, where self-assembling liposomes template a UV-curable polymer gel core. Using fluorescently-labeled lipids, protein, and hydrophobic molecules, we have characterized their formation, purification, stability, and encapsulation efficiency via common instrumentation methods such as dynamic light scattering (DLS), matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS), UV-Visible spectroscopy, fluorescence spectroscopy, and single particle total internal reflection fluorescence (TIRF) microscopy...
November 15, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/29141223/gradients-of-rac1-nanoclusters-support-spatial-patterns-of-rac1-signaling
#19
Amanda Remorino, Simon De Beco, Fanny Cayrac, Fahima Di Federico, Gaetan Cornilleau, Alexis Gautreau, Maria Carla Parrini, Jean-Baptiste Masson, Maxime Dahan, Mathieu Coppey
Rac1 is a small RhoGTPase switch that orchestrates actin branching in space and time and protrusion/retraction cycles of the lamellipodia at the cell front during mesenchymal migration. Biosensor imaging has revealed a graded concentration of active GTP-loaded Rac1 in protruding regions of the cell. Here, using single-molecule imaging and super-resolution microscopy, we show an additional supramolecular organization of Rac1. We find that Rac1 partitions and is immobilized into nanoclusters of 50-100 molecules each...
November 14, 2017: Cell Reports
https://www.readbyqxmd.com/read/29140702/influence-of-the-carotenoid-composition-on-the-conformational-dynamics-of-photosynthetic-light-harvesting-complexes
#20
Marijonas Tutkus, Jevgenij Chmeliov, Danielis Rutkauskas, Alexander V Ruban, Leonas Valkunas
Nonphotochemical quenching (NPQ) is the major self-regulatory mechanism of green plants, performed on a molecular level to protect them from an overexcitation during the direct sunlight. It is believed that NPQ becomes available due to conformational dynamics of the light-harvesting photosynthetic complexes and involves a direct participation of carotenoids. In this work, we perform a single-molecule microscopy on major light-harvesting complexes (LHCII) from different Arabidopsis thaliana mutants exhibiting various carotenoid composition...
November 21, 2017: Journal of Physical Chemistry Letters
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