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https://www.readbyqxmd.com/read/29148799/uniaxial-2d-superlattice-of-fe4-molecular-magnets-on-graphene
#1
Luca Gragnaniello, Fabian Paschke, Philipp Erler, Peter Schmitt, Nicole Barth, Sabina Simon, Harald Brune, Stefano Rusponi, Mikhail Fonin
We demonstrate that electrospray deposition enables the fabrication of highly periodic self-assembled arrays of Fe4H single molecule magnets on graphene/Ir(111). The energetic positions of molecular states are probed by means of scanning tunneling spectroscopy, showing pronounced long- and short-ranged spatial modulations, indicating the presence of both locally varying intermolecular as well as adsorption-site dependent molecule-substrate interactions. From the magnetic field dependence of the X-ray magnetic circular dichroism signal, we infer that the magnetic easy axis of each Fe4H molecule is oriented perpendicular to the sample surface and that after the deposition the value of the uniaxial anisotropy is identical to the one in bulk...
November 17, 2017: Nano Letters
https://www.readbyqxmd.com/read/29148737/site-specific-one-to-one-click-coupling-of-single-proteins-to-individual-carbon-nanotubes-a-single-molecule-approach
#2
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
#3
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/29147545/protein-labeling-for-live-cell-fluorescence-microscopy-with-a-highly-photostable-renewable-signal
#4
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/29146902/single-molecule-multiplexed-nanopore-protein-screening-in-human-serum-using-aptamer-modified-dna-carriers
#5
Jasmine Y Y Sze, Aleksandar P Ivanov, Anthony E G Cass, Joshua B Edel
The capability to screen a range of proteins at the single-molecule level with enhanced selectivity in biological fluids has been in part a driving force in developing future diagnostic and therapeutic strategies. The combination of nanopore sensing and nucleic acid aptamer recognition comes close to this ideal due to the ease of multiplexing, without the need for expensive labelling methods or extensive sample pre-treatment. Here, we demonstrate a fully flexible, scalable and low-cost detection platform to sense multiple protein targets simultaneously by grafting specific sequences along the backbone of a double-stranded DNA carrier...
November 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/29145649/single-molecule-compaction-of-megabase-long-chromatin-molecules-by-multivalent-cations
#6
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/29145633/the-initiation-propagation-and-dynamics-of-crispr-spycas9-r-loop-complex
#7
Yan Zeng, Yang Cui, Yong Zhang, Yanruo Zhang, Meng Liang, Hui Chen, Jie Lan, Guangtao Song, Jizhong Lou
CRISPR-Cas9 system has been widely used for efficient genome editing. Although the structures of Cas9 protein in complex with single-guided RNA (sgRNA) and target DNA have been resolved, the molecular details about the formation of Cas9 endonuclease R-loop structure remain elusive. Here we examine the DNA cleavage activities of Streptococcus pyogenes Cas9 (SpyCas9) and its mutants using various target sequences and study the conformational dynamics of R-loop structure during target binding using single-molecule fluorescence energy transfer (smFRET) technique...
November 14, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/29144729/an-optical-nanoantenna-for-single-molecule-based-detection-of-zika-virus-nucleic-acids-without-molecular-multiplication
#8
Sarah Elisabeth Ochmann, Carolin Vietz, Kateryna Trofymchuk, Guillermo P Acuna, Birka Lalkens, Philip Tinnefeld
Due to the limited signal-to-background ratio, molecular diagnostics requires molecular amplification of the target molecules or molecular signal amplification after target recognition. For direct molecular detection, we demonstrate a purely physical fluorescence enhancement process which can elevate the fluorescence signal of single fluorescent dyes by several orders of magnitude. To this end, DNA origami-based optical antennas with a height of around 125 nm are used, which utilize metallic nanoparticles to create a hotspot where fluorescence signals are enhanced by plasmonic effects...
November 16, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29144454/dynamics-of-p-type-atpase-transport-revealed-by-single-molecule-fret
#9
Mateusz Dyla, Daniel S Terry, Magnus Kjaergaard, Thomas L-M Sørensen, Jacob Lauwring Andersen, Jens Peter Andersen, Charlotte Rohde Knudsen, Roger B Altman, Poul Nissen, Scott C Blanchard
Phosphorylation-type (P-type) ATPases are ubiquitous primary transporters that pump cations across cell membranes through the formation and breakdown of a phosphoenzyme intermediate. Structural investigations suggest that the transport mechanism is defined by conformational changes in the cytoplasmic domains of the protein that are allosterically coupled to transmembrane helices so as to expose ion binding sites to alternate sides of the membrane. Here, we have used single-molecule fluorescence resonance energy transfer to directly observe conformational changes associated with the functional transitions in the Listeria monocytogenes Ca(2+)-ATPase (LMCA1), an orthologue of eukaryotic Ca(2+)-ATPases...
November 16, 2017: Nature
https://www.readbyqxmd.com/read/29144410/evaluation-of-different-single-walled-carbon-nanotube-surface-coatings-for-single-particle-tracking-applications-in-biological-environments
#10
Zhenghong Gao, Noémie Danné, Antoine Guillaume Godin, Brahim Lounis, Laurent Cognet
Fluorescence imaging of biological systems down to the single-molecule level has generated many advances in cellular biology. For applications within intact tissue, single-walled carbon nanotubes (SWCNTs) are emerging as distinctive single-molecule nanoprobes, due to their near-infrared photoluminescence properties. For this, SWCNT surfaces must be coated using adequate molecular moieties. Yet, the choice of the suspension agent is critical since it influences both the chemical and emission properties of the SWCNTs within their environment...
November 16, 2017: Nanomaterials
https://www.readbyqxmd.com/read/29143447/investigation-of-the-interactions-between-aptamer-and-misfolded-proteins-from-monomer-and-oligomer-to-fibril-by-single-molecule-force-spectroscopy
#11
Yan Zheng, Qing Wang, Xiaohai Yang, Zhiping Li, Lei Gao, Hua Zhang, Wenyan Nie, Xiuhua Geng, Kemin Wang
Increasing knowledge on the understanding interactions of aptamer with misfolded proteins (including monomer, oligomer, and amyloid fibril) is crucial for development of aggregation inhibitors and diagnosis of amyloid diseases. Herein, the interactions of lysozyme monomer-, oligomer-, and amyloid fibril-aptamer were investigated using single-molecule force spectroscopy. The results revealed that the aptamer screened against lysozyme monomer could also bind to oligomer and amyloid fibril, in spite of the recognition at a lower binding probability...
November 16, 2017: Journal of Molecular Recognition: JMR
https://www.readbyqxmd.com/read/29143332/accurate-prediction-and-elucidation-of-drug-resistance-based-on-the-robust-and-reproducible-chemoresponse-communities
#12
Enyu Dai, Jing Wang, Feng Yang, Xu Zhou, Qian Song, Shuyuan Wang, Xuexin Yu, Dianming Liu, Qian Yang, Hong Dai, Wei Jiang, Hong Ling
Selecting the available treatment for each cancer patient from genomic context is a core goal of precision medicine, but innovative approaches with mechanism interpretation and improved performance are still highly needed. Through utilizing in vitro chemotherapy response data coupled with gene and miRNA expression profiles, we applied a network-based approach that identified markers not as individual molecules but as functional groups extracted from the integrated transcription factor and miRNA regulatory network...
November 16, 2017: International Journal of Cancer. Journal International du Cancer
https://www.readbyqxmd.com/read/29141419/development-and-application-of-a-2-electron-reduced-density-matrix-approach-to-electron-transport-via-molecular-junctions
#13
Erik P Hoy, David A Mazziotti, Tamar Seideman
Can an electronic device be constructed using only a single molecule? Since this question was first asked by Aviram and Ratner in the 1970s [Chem. Phys. Lett. 29, 277 (1974)], the field of molecular electronics has exploded with significant experimental advancements in the understanding of the charge transport properties of single molecule devices. Efforts to explain the results of these experiments and identify promising new candidate molecules for molecular devices have led to the development of numerous new theoretical methods including the current standard theoretical approach for studying single molecule charge transport, i...
November 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29141223/gradients-of-rac1-nanoclusters-support-spatial-patterns-of-rac1-signaling
#14
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/29141138/differential-effects-of-strand-asymmetry-on-the-energetics-and-structural-flexibility-of-dna-internal-loops
#15
Thao Tran, Brian Cannon
Internal loops within structured nucleic acids disrupt local base-stacking and destabilize neighboring helical domains; however, these structural motifs also expand the conformational and functional capabilities for structured nucleic acids. Variations in size, distribution of loop nucleotides on opposing strands (strand asymmetry), and sequence alter their biophysical properties. Here, the thermodynamics and structural flexibility of poly(T)-rich DNA internal loops were systematically investigated in terms of loop size and strand asymmetry...
November 15, 2017: Biochemistry
https://www.readbyqxmd.com/read/29141068/new-insight-into-the-pathophysiology-of-hair-loss-trigger-a-paradigm-shift-in-the-treatment-approach
#16
Neil S Sadick, Valerie D Callender, Leon H Kircik, Sophia Kogan
<p>Hair loss affects millions of men and women of all ages and ethnicities, impacting appearance, social interactions, and psycho-emotional well-being. Although a number of options are available, they are limited, carry a potential risk of side effects, and none have proven to be comprehensive for treatment of hair loss. Across the spectrum of hair loss disorders, there has long been a segmentation into distinct mechanisms, driving the main trend in current therapeutics to focus on targeting single molecules or pathways...
November 1, 2017: Journal of Drugs in Dermatology: JDD
https://www.readbyqxmd.com/read/29140702/influence-of-the-carotenoid-composition-on-the-conformational-dynamics-of-photosynthetic-light-harvesting-complexes
#17
Marijonas Tutkus, Jevgenij Chmeliov, Danielis Rutkauskas, Alexander V Ruban, Leonas Valkunas
Non-photochemical quenching (NPQ) is the major self-regulatory mechanism of green plant, performed on a molecular level to protect them from an over-excitation 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 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29139483/surface-enhanced-raman-spectroscopy-bottlenecks-and-future-directions
#18
Rajapandiyan Panneerselvam, Guo-Kun Liu, Yao-Hui Wang, Jun-Yang Liu, Song-Yuan Ding, Jian-Feng Li, De-Yin Wu, Zhong-Qun Tian
In this feature article, we discuss in detail developmental bottleneck issues in Raman spectroscopy in its early stages and surface-enhanced Raman spectroscopy (SERS) in the past four decades. We divide SERS research into two different directions with different targets. Fundamental research is extending the limits of SERS to single-molecule, sub-nanometer resolution and femtosecond processes. In contrast, practical research is expanding the range of applications with the aim of providing versatile analytical tools for surface, materials, life, environmental, forensic and food sciences and also commercial instruments for use in daily life...
November 15, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29138775/microsecond-resolved-single-molecule-fret-time-series-measurements-based-on-the-line-confocal-optical-system-combined-with-hybrid-photodetectors
#19
Hiroyuki Oikawa, Takumi Takahashi, Supawich Kamonprasertsuk, Satoshi Takahashi
Single-molecule (sm) fluorescence time series measurements based on the line confocal optical system are a powerful strategy for the investigation of the structure, dynamics, and heterogeneity of biological macromolecules. This method enables the detection of more than several thousands of fluorescence photons per millisecond from single fluorophores, implying that the potential time resolution for measurements of the fluorescence resonance energy transfer (FRET) efficiency is 10 μs. However, the necessity of using imaging photodetectors in the method limits the time resolution in the FRET efficiency measurements to approximately 100 μs...
November 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29138465/fine-tuning-the-energy-barrier-of-molecular-nanomagnets-via-lattice-solvent-molecules
#20
Cai-Ming Liu, De-Qing Zhang, Dao-Ben Zhu
Solvents play important roles in our lives, they are also of interest in molecular materials, especially for molecular magnets. The solvatomagnetic effect is generally used for trigger and/or regulation of magnetic properties in molecule-based systems, however, molecular nanomagnets showing solvatomagnetic effects are very difficult to obtain. Here we report four 3d-4f heterometallic cluster complexes containing ROH lattice solvent molecules, [Cu3Tb2(H3L)2(OAc)2(hfac)4]∙2ROH {H6L = 1,3-Bis[tris(hydroxymethyl)methylamino]propane, hfac(-) = hexafluoroacetylacetonate; R = CH3, 1; R = C2H5, 2; R = C3H7, 3; R = H, 4}...
November 14, 2017: Scientific Reports
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