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Atomic force microscopy

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https://www.readbyqxmd.com/read/28230209/direct-observation-of-the-dynamics-of-single-metal-ions-at-the-interface-with-solids-in-aqueous-solutions
#1
Maria Ricci, William Trewby, Clodomiro Cafolla, Kislon Voïtchovsky
The dynamics of ions adsorbed at the surface of immersed charged solids plays a central role in countless natural and industrial processes such as crystal growth, heterogeneous catalysis, electrochemistry, or biological function. Electrokinetic measurements typically distinguish between a so-called Stern layer of ions and water molecules directly adsorbed on to the solid's surface, and a diffuse layer of ions further away from the surface. Dynamics within the Stern layer remain poorly understood, largely owing to a lack of in-situ atomic-level insights...
February 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28230082/tubz-filament-assembly-dynamics-requires-the-flexible-c-terminal-tail
#2
Maria E Fuentes-Pérez, Rafael Núñez-Ramírez, Alejandro Martín-González, David Juan-Rodríguez, Oscar Llorca, Fernando Moreno-Herrero, Maria A Oliva
Cytomotive filaments are essential for the spatial organization in cells, showing a dynamic behavior based on nucleotide hydrolysis. TubZ is a tubulin-like protein that functions in extrachromosomal DNA movement within bacteria. TubZ filaments grow in a helical fashion following treadmilling or dynamic instability, although the underlying mechanism is unclear. We have unraveled the molecular basis for filament assembly and dynamics combining electron and atomic force microscopy and biochemical analyses. Our findings suggest that GTP caps retain the filament helical structure and hydrolysis triggers filament stiffening upon disassembly...
February 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28225570/washless-method-enables-multilayer-coating-of-an-aggregation-prone-nanoparticulate-drug-delivery-system-with-enhanced-yields-colloidal-stability-and-scalability
#3
Lamees Nayef, Rafael Castiello, Maryam Tabrizian
Aggregation is frequently encountered during coating nanoparticles, especially when the core is not solid and the coating polyelectrolytes are weak. Here, the coating of a nanoliposome with two weak polyelectrolytes, alginate and chitosan, is investigated. First, quartz crystal microbalance with dissipation, atomic force microscopy, scanning electron microscopy, and energy dispersive spectroscopy analyses confirm the feasibility of firm adsorption of up to 16 layers of weak polyelectrolytes to the liposomal surface...
February 22, 2017: Macromolecular Bioscience
https://www.readbyqxmd.com/read/28225121/the-local-electronic-properties-of-individual-pt-atoms-adsorbed-on-tio2-110-studied-by-kelvin-probe-force-microscopy-and-first-principles-simulations
#4
Ayhan Yurtsever, Delia Fernández-Torre, Jo Onoda, Masayuki Abe, Seizo Morita, Yoshiaki Sugimoto, Rubén Pérez
Noble metal nanostructures dispersed on metal oxide surfaces have applications in diverse areas such as catalysis, chemical sensing, and energy harvesting. Their reactivity, chemical selectivity, stability, and light absorption properties are controlled by the interactions at the metal/oxide interface. Single-atom metal adsorbates on the rutile TiO2(110)-(1 × 1) surface have become a paradigmatic model to characterize those interactions and to understand the unique electronic properties of these supported nanostructures...
February 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28223315/the-focal-adhesion-targeting-fat-domain-of-p130-crk-associated-substrate-p130cas-confers-mechanosensing-function
#5
Peta M Bradbury, Kylie Turner, Camilla Mitchell, Kaitlyn R Griffin, Shiloh Middlemiss, Loretta Lau, Rebecca Dagg, Elena Taran, Justin Cooper-White, Ben Fabry, Geraldine M O'Neill
The Cas family of focal adhesion proteins contain a highly conserved C-terminal focal adhesion targeting (FAT) domain. To determine the role of the FAT domain we compared wildtype exogenous NEDD9 with a hybrid construct in which the NEDD9 FAT domain is exchanged for the p130Cas FAT domain. Fluorescence recovery after photobleaching (FRAP) revealed significantly slowed exchange of the fusion protein at focal adhesions and significantly slower 2D migration. No differences were detected in cell stiffness measured with Atomic Force Microscopy (AFM) and cell adhesion forces measured with a magnetic tweezer device...
February 21, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28222259/band-alignment-at-gan-single-layer-wse2-interface
#6
Malleswararao Tangi, Pawan Mishra, Chien-Chih Tseng, Tien Khee Ng, Mohamed Nejib Hedhili, Dalaver H Anjum, Mohd Sharizal Alias, Nini Wei, Lain-Jong Li, Boon S Ooi
We study the band discontinuity at the GaN/single-layer (SL) WSe2 heterointerface. The GaN thin layer is epitaxially grown by molecular beam epitaxy on chemically vapor deposited SL-WSe2/c-sapphire. We confirm that the WSe2 was formed as an SL from structural and optical analyses using atomic force microscopy, scanning transmission electron microscopy, micro-Raman, absorbance, and micro-photoluminescence spectra. The determination of band offset parameters at the GaN/SL-WSe2 heterojunction is obtained by high-resolution x-ray photoelectron spectroscopy, electron affinities and the electronic bandgap values of SL-WSe2 and GaN...
February 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28221704/in-plane-2h-1t-mote2-homojunctions-synthesized-by-flux-controlled-phase-engineering
#7
Youngdong Yoo, Zachary P DeGregorio, Yang Su, Steven J Koester, James E Johns
The fabrication of in-plane 2H-1T' MoTe2 homojunctions by the flux-controlled, phase-engineering of few-layer MoTe2 from Mo nanoislands is reported. The phase of few-layer MoTe2 is controlled by simply changing Te atomic flux controlled by the temperature of the reaction vessel. Few-layer 2H MoTe2 is formed with high Te flux, while few-layer 1T' MoTe2 is obtained with low Te flux. With medium flux, few-layer in-plane 2H-1T' MoTe2 homojunctions are synthesized. As-synthesized MoTe2 is characterized by Raman spectroscopy and X-ray photoelectron spectroscopy...
February 21, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28221026/nanomechanics-of-ph-responsive-drug-loaded-bi-layered-polymer-grafts
#8
Prathima Chandra Nalam, Hyun-Su Lee, Nupur Bhatt, Robert W Carpick, David M Eckmann, Russell J Composto
Stimuli-responsive polymer films play an important role in the development of smart antibacterial coatings. In this study, we consider complementary architectures of polyelectrolyte films including a thin chitosan layer (CH), poly (acrylic acid) (PAA) brushes and a bilayer structure of CH grafted to PAA brushes (CH/PAA) as possible candidates for targeted drug delivery platforms. Atomic force microscopy (AFM) was employed to study the structure-mechanical property relationship for these mono- and bi- layered polymer grafts at pH 7...
February 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28220836/nucleobindin-1-binds-to-multiple-types-of-pre-fibrillar-amyloid-and-inhibits-fibrillization
#9
Alessandra Bonito-Oliva, Shahar Barbash, Thomas P Sakmar, W Vallen Graham
During amyloid fibril formation, amyloidogenic polypeptides misfold and self assemble into soluble pre-fibrillar aggregates, i.e., protofibrils, which elongate and mature into insoluble fibrillar aggregates. An emerging class of chaperones, chaperone-like amyloid binding proteins (CLABPs), has been shown to interfere with aggregation of particular misfolded amyloid peptides or proteins. We have discovered that the calcium-binding protein nuclebindin-1 (NUCB1) is a novel CLABP. We show that NUCB1 inhibits aggregation of islet-amyloid polypeptide associated with type 2 diabetes mellitus, a-synuclein associated with Parkinson's disease, transthyretin V30M mutant associated with familial amyloid polyneuropathy, and Aβ42 associated with Alzheimer's disease by stabilizing their respective protofibril intermediates...
February 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28220757/photoexfoliation-of-two-dimensional-materials-through-continuous-uv-irradiation
#10
Wai-Chen Lin, Ming-Kai Chuang, Muchamed L Keshtov, Ganesh D Sharma, Fang-Chung Chen
This paper describes the preparation of fluorinated graphene nanosheets (FGNs) through photoexfoliation of fluorinated graphite (FG) in the liquid phase. We discovered that UV irradiation of FG dispersions in N-methyl-2-pyrolidone facilitated exfoliation to give FGNs. Transmission electron microscopy and atomic force microscopy revealed that the average thickness of the FGNs was approximately 3 nm; they were considerably thinner than the nanosheets prepared using a conventional sonication approach. Furthermore, when the FGNs were deposited uniformly onto substrates (through spin coating), they formed effective cathode interlayers for polymer solar cells (PSCs), the efficiency of which was 60% greater than that of PSCs containing FGNs prepared through ultrasonication...
February 21, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28219250/luminometric-nanoparticle-based-assay-for-high-sensitivity-detection-of-%C3%AE-amyloid-aggregation
#11
Sari Pihlasalo, Takahiro Deguchi, Maria Virtamo, Jenna Jacobino, Karthik Chary, Francisco R López-Picón, Gerda Brunhofer-Bolzer, Roope Huttunen, Adyary Fallarero, Pia Vuorela, Harri Härmä
A nanoparticle-based assay utilizing time-resolved luminescence resonance energy transfer (TR-LRET) was developed for the detection of β-amyloid aggregation. The assay is based on the competitive adsorption of the sample and the acceptor-labeled protein to donor europium(III) polystyrene nanoparticles. The performance of the assay was demonstrated by following the fibrillization of β-amyloid peptide 1-42 (Aβ42) as a function of time and by comparing to the reference methods atomic force microscopy (AFM) and thioflavin T (ThT) assay...
February 21, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28219033/using-a-facile-experimental-manipulation-to-fabricate-and-tune-a-polyoxometalate-cholesterol-hybrid-material
#12
Hai-Kuan Yang, Ling-Ling Liu, Xin Yuan, Shi-Mei Wu
In this work, we describe how the toluene and DMF addition order influences the gelation behaviors and supramolecular structures of a self-assembled polyoxometalate-cholesterol hybrid. Morphological studies of the dried xerogel samples were performed with transmission electron microscopy and atomic force microscopy, revealing that the order of solvent addition directed the self-assembly of polyoxometalate-cholesterol hybrids toward the formation of organogels with different supramolecular structures. In the case of organogel 1, which was formed by adding DMF dropwise into a hybrid-containing toluene solution, the characteristic organogel morphology contained a three-dimensional fibrous network structure...
February 14, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28218833/atomic-force-microscopy-thermally-assisted-microsampling-with-atmospheric-pressure-temperature-ramped-thermal-desorption-ionization-mass-spectrometry-analysis
#13
William D Hoffmann, Vilmos Kertesz, Bernadeta R Srijanto, Gary J Van Berkel
The use of atomic force microscopy controlled nanothermal analysis probes for reproducible spatially resolved thermally assisted sampling of micrometer-sized areas (ca. 11 × 17 μm wide × 2.4 μm deep) from relatively low number-average molecular weight (Mn < 3000) polydisperse thin films of poly(2-vinylpyridine) (P2VP) is presented. Following sampling, the nanothermal analysis probes were moved up from the surface and the probe temperature ramped to liberate the sampled materials into the gas phase for atmospheric pressure chemical ionization and mass spectrometric analysis...
February 20, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28218510/exceptional-dewetting-of-organic-semiconductor-films-the-case-of-dinaphthothienothiophene-dntt-at-dielectric-interfaces
#14
Tobias Breuer, Andrea Karthäuser, Hagen W Klemm, Francesca Genuzio, Gina Peschel, Alexander Fuhrich, Thomas Schmidt, Gregor Witte
The novel organic semiconductor dinaphthothienothiophene (DNTT) has gained considerable interest because its large charge carrier mobility and distinct chemical robustness enable the fabrication of organic field effect transistors with remarkable long-term stability under ambient conditions. Structural aspects of DNTT films and their control, however, remain so far largely unexplored. Interestingly, the crystalline structure of DNTT is rather similar to that of the prototypical pentacene, for which the molecular orientation in crystalline thin films can be controlled by means of interface-mediated growth...
February 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28217790/nanotribological-properties-of-nanostructured-poly-cysteine-methacrylate-brushes
#15
Omed Al-Jaf, Abdullah Alswieleh, Steven P Armes, Graham J Leggett
The nanomechanical properties of zwitterionic poly(cysteine methacrylate) (PCysMA) brushes grown from planar surfaces by atom transfer radical polymerisation have been characterised by friction force microscopy (FFM). FFM provides quantitative insights into polymer structure-property relationships and in particular illuminates the dependence of brush swelling on chain packing in nanostructured materials. In ethanol, which is a poor solvent for PCysMA, a linear friction-load relationship is observed, indicating that energy dissipation occurs primarily through ploughing...
February 20, 2017: Soft Matter
https://www.readbyqxmd.com/read/28217547/a-study-of-the-formation-of-magnetically-active-solid-dispersions-of-phenacetin-using-atomic-and-magnetic-force-microscopy
#16
Liana Stanislavovna Usmanova, Marat Akhmedovich Ziganshin, Valery Vilenovich Gorbatchuk, Sufia Askhatovna Ziganshina, Dmitry Anatolevich Bizyaev, Anastas Akhmetovich Bukharaev, Timur Anvarovich Mukhametzyanov, Alexander Vladimirovich Gerasimov
A lot of pharmaceutical substances have a poor solubility that limits their absorption and distribution to the targeted sites to elicit the desired action without causing untoward effects on healthy cells or tissues. For such drugs, new modes of delivery have to be developed for efficient and effective delivery of the drug to the target site. Formation of magnetically active solid dispersion of such drugs could be a useful approach to addressing this problem because they combine targeted delivery and good solubility...
January 2017: Journal of Advanced Pharmaceutical Technology & Research
https://www.readbyqxmd.com/read/28216672/enhancement-of-local-photovoltaic-current-at-ferroelectric-domain-walls-in-bifeo3
#17
Ming-Min Yang, Akash Bhatnagar, Zheng-Dong Luo, Marin Alexe
Domain walls, which are intrinsically two dimensional nano-objects exhibiting nontrivial electronic and magnetic behaviours, have been proven to play a crucial role in photovoltaic properties of ferroelectrics. Despite this recognition, the electronic properties of domain walls under illumination until now have been accessible only to macroscopic studies and their effects upon the conduction of photovoltaic current still remain elusive. The lack of understanding hinders the developing of nanoscale devices based on ferroelectric domain walls...
February 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28216572/in-vitro-characterization-of-the-two-stage-non-classical-reassembly-pathway-of-s-layers
#18
Andreas Breitwieser, Jagoba Iturri, Jose-Luis Toca-Herrera, Uwe B Sleytr, Dietmar Pum
The recombinant bacterial surface layer (S-layer) protein rSbpA of Lysinibacillus sphaericus CCM 2177 is an ideal model system to study non-classical nucleation and growth of protein crystals at surfaces since the recrystallization process may be separated into two distinct steps: (i) adsorption of S-layer protein monomers on silicon surfaces is completed within 5 min and the amount of bound S-layer protein sufficient for the subsequent formation of a closed crystalline monolayer; (ii) the recrystallization process is triggered-after washing away the unbound S-layer protein-by the addition of a CaCl₂ containing buffer solution, and completed after approximately 2 h...
February 14, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28215921/role-of-myocardial-collagen-in-severe-aortic-stenosis-with-preserved-ejection-fraction-and-symptoms-of-heart-failure
#19
Kattalin Echegaray, Ion Andreu, Ane Lazkano, Iñaki Villanueva, Alberto Sáenz, María Reyes Elizalde, Tomás Echeverría, Begoña López, Asier Garro, Arantxa González, Elena Zubillaga, Itziar Solla, Iñaki Sanz, Jesús González, Alberto Elósegui-Artola, Pere Roca-Cusachs, Javier Díez, Susana Ravassa, Ramón Querejeta
INTRODUCTION AND OBJECTIVES: We investigated the anatomical localization, biomechanical properties, and molecular phenotype of myocardial collagen tissue in 40 patients with severe aortic stenosis with preserved ejection fraction and symptoms of heart failure. METHODS: Two transmural biopsies were taken from the left ventricular free wall. Mysial and nonmysial regions of the collagen network were analyzed. Myocardial collagen volume fraction (CVF) was measured by picrosirius red staining...
February 16, 2017: Revista Española de Cardiología
https://www.readbyqxmd.com/read/28215536/gel-gel-phase-separation-within-milk-sphingomyelin-domains-revealed-at-the-nanoscale-using-atomic-force-microscopy
#20
Fanny Guyomarc'h, Maohui Chen, Oumaima Et-Thakafy, Shan Zou, Christelle Lopez
The milk sphingomyelin (MSM) is involved in the formation of ordered lipid domains in the biological milk fat globule membrane (MFGM), where it accounts for about 30% of the polar lipids. Moreover, MSM exhibits a large variety in saturated acyl chain lengths (from C16:0 to C24:0-SM) compared to other natural sphingomyelins, which may impact the packing of MSM molecular species in the gel phase domains and the topography of the MFGM. To investigate this, supported lipid bilayers of synthetic sphingomyelins or of MSM-containing mixtures, including a MFGM polar lipid extract, were imaged at temperatures below the Tm of MSM (i...
February 16, 2017: Biochimica et Biophysica Acta
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