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https://www.readbyqxmd.com/read/29792809/thionine-self-assembled-structures-on-graphene-formation-organization-and-doping
#1
Thiago Sousa, Thales Fernando Damasceno Fernandes, Matheus J S Matos, Eduardo Nery Duarte Araujo, Mario S C Mazzoni, Bernardo R A Neves, Flávio Plentz
The association of organic molecules with 2D materials, creating hybrid systems with mutual influences, constitutes an important testbed for both basic science self-assembly studies and perspective applications. Following this concept, in this work, we show a rich phenomenology that is involved in the interaction of thionine with graphene, leading to a hybrid material formed by well-organized self-assembled structures atop graphene. This composite system is investigated by atomic force microscopy, electric transport measurements, and first principles calculations, which show: 1) an interesting time evolution of thionine self-assembled structures atop graphene; 2) the final molecular assembly is highly oriented (in accordance with the underlying graphene surface symmetry); and 3) thionine introduces a strong n-type doping effect in graphene...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29792710/measuring-the-adhesion-forces-for-the-multivalent-binding-of-vancomycin-conjugated-dendrimer-to-bacterial-cell-wall-peptide
#2
Elizabeth Peterson, Christine Joseph, Hannah Peterson, Rachael Bouwman, Shengzhuang Tang, Jayme Cannon, Kumar Sinniah, Seok Ki Choi
Multivalent ligand-receptor interaction provides the fundamental basis for the hypothetical notion that high binding avidity relates to the strong force of adhesion. Despite its increasing importance in the design of targeted nanoconjugates, an understanding of the physical forces underlying the multivalent interaction remains a subject of urgent investigation. In this study, we designed three vancomycin (Van)-conjugated dendrimers G5(Van)n (n = mean valency = 0, 1, 4) for bacterial targeting with generation 5 (G5) poly(amidoamine) dendrimer as a multivalent scaffold, and evaluated both their binding avidity and physical force of adhesion to a bacterial model surface by employing surface plasmon resonance (SPR) spectroscopy and atomic force microscopy (AFM)...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29791160/interaction-of-zwitterionic-and-ionic-monomers-with-graphene-surfaces
#3
Suguna Perumal, Atchudan Raji, In Woo Cheong
Measurement of the interaction force between two materials provides important information on various properties, such as adsorption, binding or compatibility for coatings, adhesion, and composites. The interaction forces of zwitterionic and ionic monomers with graphite platelets (G) and reduced graphene oxide (rGO) surfaces were systematically investigated using atomic force microscopy (AFM) in air and water. The monomers examined were 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (MPC), [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBE), [2-(acryloyloxy)ethyl]trimethylammonium chloride (ATC), and 2-methyl-2-propene-1-sulfonic acid sodium (MSS)...
May 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29790339/highly-oriented-monolayer-graphene-grown-on-a-cu-ni-111-alloy-foil
#4
Ming Huang, Mandakini Biswal, Hyo Ju Park, Sunghwan Jin, Deshun Qu, Seokmo Hong, Zhili Zhu, Lu Qiu, Da Luo, Xiaochi Liu, Zheng Yang, Zhongliu Liu, Yuan Huang, Hyunseob Lim, Won Jong Yoo, Feng Ding, Yeliang Wang, Zonghoon Lee, Rodney S Ruoff
Fast-growth of single crystal monolayer graphene by CVD using methane and hydrogen has been achieved on "homemade" single crystal Cu/Ni(111) alloy foils over large area. Full coverage was achieved in 5 min or less for a particular range of composition (1.3 at.% to 8.6 at.% Ni), as compared to 60 min for a pure Cu(111) foil under identical growth conditions. These are the bulk atomic percentages of Ni, as a superstructure at the surface of these foils with stoichiometry Cu6 Ni1 (for 1.3 to 7.8 bulk at...
May 23, 2018: ACS Nano
https://www.readbyqxmd.com/read/29790208/changes-in-nano-mechanical-properties-of-human-epidermal-cornified-cells-depending-on-their-proximity-to-the-skin-surface
#5
Pascale Milani, Julien Chlasta, Rawad Abdayem, Sanja Kezic, Marek Haftek
During formation of the stratum corneum (SC) barrier, terminally differentiated keratinocytes continue their maturation process within the dead superficial epidermal layer. Morphological studies of isolated human corneocytes have revealed differences between cornified envelopes purified from the deep and superficial SC. We used atomic force microscopy to measure the mechanical properties of native human corneocytes harvested by tape-stripping from different SC depths. Various conditions of data acquisition have been tested and optimized, in order to obtain exploitable and reproducible results...
May 22, 2018: Journal of Molecular Recognition: JMR
https://www.readbyqxmd.com/read/29788718/morphology-and-physical-properties-of-hydrophilic-polymer-modified-lipids-in-supported-lipid-bilayers
#6
Yasuhiro Kakimoto, Yoshihiro Tachihara, Yoshiaki Okamoto, Keisuke Miyazawa, Takeshi Fukuma, Ryugo Tero
Lipid molecules such as glycolipids which are modified with hydrophilic biopolymers participate in the biochemical reactions occurring on cell membranes. Their functions and efficiency are determined by the formation of microdomains and their physical properties. We investigated the morphology and properties of domains induced by the hydrophilic-polymer-modified lipid applying poly-ethylene glycol (PEG)-modified lipid as a model modified lipid. We formed supported lipid bilayers (SLBs) using a 0-10 mol % range of PEG-modified lipid concentration (CPEG)...
May 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29788158/cell-wall-bound-silicon-optimizes-ammonium-uptake-and-metabolism-in-rice-cells
#7
Huachun Sheng, Jie Ma, Junbao Pu, Lijun Wang
Background and Aims: Turgor-driven plant cell growth depends on cell wall structure and mechanics. Strengthening of cell walls on the basis of an association and interaction with silicon (Si) could lead to improved nutrient uptake and optimized growth and metabolism in rice (Oryza sativa). However, the structural basis and physiological mechanisms of nutrient uptake and metabolism optimization under Si assistance remain obscure. Methods: Single-cell level biophysical measurements, including in situ non-invasive micro-testing (NMT) of NH4+ ion fluxes, atomic force microscopy (AFM) of cell walls, and electrolyte leakage and membrane potential, as well as whole-cell proteomics using isobaric tags for relative and absolute quantification (iTRAQ), were performed...
May 16, 2018: Annals of Botany
https://www.readbyqxmd.com/read/29786838/edible-gum-phenolic-lipid-incorporated-gluten-films-for-food-packaging
#8
Rui Liu, Xu Cong, Yingshi Song, Tao Wu, Min Zhang
The aim of this investigation was to improve the barrier and mechanical properties of gluten films and further explore their application in the packaging of seasonings. The effects of flaxseed gum (FG), oligomeric procyanidins (OPCs), and lauric acid (LA) on the water vapor permeability (WVP), mechanical properties, and peroxide value (POV) were determined. FG and OPCs improved the WVP properties of the gluten films, whereas LA significantly improved the oxygen-barrier properties. The FG/OPCs/LA/GP composite film was then optimized, and the morphological, microstructural, and thermal properties of the composite gluten film were investigated by scanning electron microscopy, atomic force microscopy, surface hydrophobicity analysis; Fourier transform infrared spectroscopy; thermal gravimetric analysis, respectively...
May 22, 2018: Journal of Food Science
https://www.readbyqxmd.com/read/29785538/stress-phase-angle-regulates-differentiation-of-human-adipose-derived-stem-cells-toward-endothelial-phenotype
#9
Shahrokh Shojaei, Mohammad Tafazzoli-Shadpour, Mohammad Ali Shokrgozar, Nooshin Haghighipour, Fatemeh Hejazi Jahromi
Endothelial cells are subjected to cyclic shear by pulsatile blood flow and pressures due to circumferential stresses. Although most of the researches on this topic have considered the effects of these two biomechanical forces separately or concurrently, few studies have noticed the interaction of these cyclic loadings on endothelial behavior. Negative temporal stress phase angle, defined by the phase lag between cyclic shear and tensile stresses, is an established parameter which is known to have substantial effects on blood vessel remodeling and progression of some serious cardiovascular diseases...
May 21, 2018: Progress in Biomaterials
https://www.readbyqxmd.com/read/29785105/development-and-blood-compatibility-assessment-of-electrospun-polyvinyl-alcohol-blended-with-metallocene-polyethylene-and-plectranthus-amboinicus-pva-mpe-pa-for-bone-tissue-engineering
#10
Jie Qi, Huang Zhang, Yingzhou Wang, Mohan Prasath Mani, Saravana Kumar Jaganathan
Introduction: Currently, the design of extracellular matrix (ECM) with nanoscale properties in bone tissue engineering is challenging. For bone tissue engineering, the ECM must have certain properties such as being nontoxic, highly porous, and should not cause foreign body reactions. Materials and methods: In this study, the hybrid scaffold based on polyvinyl alcohol (PVA) blended with metallocene polyethylene (mPE) and plectranthus amboinicus (PA) was fabricated for bone tissue engineering via electrospinning...
2018: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/29784964/high-speed-photothermal-off-resonance-atomic-force-microscopy-reveals-assembly-routes-of-centriolar-scaffold-protein-sas-6
#11
Adrian P Nievergelt, Niccolò Banterle, Santiago H Andany, Pierre Gönczy, Georg E Fantner
The self-assembly of protein complexes is at the core of many fundamental biological processes 1 , ranging from the polymerization of cytoskeletal elements, such as microtubules 2 , to viral capsid formation and organelle assembly 3 . To reach a comprehensive understanding of the underlying mechanisms of self-assembly, high spatial and temporal resolutions must be attained. This is complicated by the need to not interfere with the reaction during the measurement. As self-assemblies are often governed by weak interactions, they are especially difficult to monitor with high-speed atomic force microscopy (HS-AFM) due to the non-negligible tip-sample interaction forces involved in current methods...
May 21, 2018: Nature Nanotechnology
https://www.readbyqxmd.com/read/29784951/tomographic-and-multimodal-scattering-type-scanning-near-field-optical-microscopy-with-peak-force-tapping-mode
#12
Haomin Wang, Le Wang, Devon S Jakob, Xiaoji G Xu
Scattering-type scanning near-field optical microscopy (s-SNOM) enables nanoscale spectroscopic imaging and has been instrumental for many nano-photonic discoveries and in situ studies. However, conventional s-SNOM techniques with atomic force microscopy tapping mode operation and lock-in detections do not provide direct tomographic information with explicit tip-sample distance. Here, we present a non-traditional s-SNOM technique, named peak force scattering-type scanning near-field optical microscopy (PF-SNOM), by combination of peak force tapping mode and time-gated light detection...
May 21, 2018: Nature Communications
https://www.readbyqxmd.com/read/29784272/design-and-synthesis-of-new-antitumor-agents-with-the-1-7-epoxycyclononane-framework-study-of-their-anticancer-action-mechanism-by-a-model-compound
#13
Ángel M Montaña, Julia Lorenzo, Stefano Ponzano, Maria-Filomena Sanasi
This article describes the design, synthesis and biological evaluation of a new family of antitumor agents having the 1,7-epoxycyclononane framework. We have developed a versatile synthetic methodology that allows the preparation of a chemical library with structural diversity and in good yield. The synthetic methodology has been scaled up to the multigram level and can be developed in an enantioselective fashion. The study in vitro of a model compound, in front of the cancer cell lines HL-60 and MCF-7, showed a growth inhibitory effect better than that of cisplatin...
May 18, 2018: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/29783839/doping-zno-electron-transport-layers-with-mos2-nanosheets-enhances-the-efficiency-of-polymer-solar-cells
#14
Yi-Jiun Huang, Hsiu-Cheng Chen, Hsi-Kuei Lin, Kung-Hwa Wei
In this study, we incorporated molybdenum disulfide (MoS2) nanosheets into sol-gel processing of zinc oxide (ZnO) to form ZnO:MoS2 composites for use as electron transport layers (ETLs) in inverted polymer solar cells featuring a binary bulk heterojunction active layer. We could effectively tune the energy band of the ZnO:MoS2 composite film from 4.45 to 4.22eV by varying the content of MoS2 up to 0.5 wt%, such that the composite was suitable for use in bulk heterojunction photovoltaic devices based on poly[bis(5-(2-ethylhexyl)thien-2-yl)benzodithiophene-alt-(4-(2-ethylhexyl)-3-fluorothienothiophene)-2-carboxylate-2,6-diyl)] (PTB7-TH):phenyl-C71-butryric acid methyl ester (PC71BM)...
May 22, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29783836/a-y-shaped-three-arm-structure-for-probing-bivalent-interactions-between-protein-receptor-ligand-using-afm-and-spr
#15
Subhadip Senapati, Sudipta Biswas, Saikat Manna, Robert Ros, Stuart Lindsay, Peiming Zhang
The goal of this research was to develop linkage chemistry for the study of bivalent interactions between a receptor and its ligand using atomic force microscopy (AFM) and surface plasmon resonance (SPR). We conceived a three-arm structure composed of flexible chains connected to a large rigid core with orthogonal functional groups at their ends for formation and attachment (or immobilization) of bivalent ligands. To demonstrate the principle, we chose the well-known biotin-streptavidin interaction as a model system...
May 21, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29781612/the-role-of-melatonin-in-affecting-cell-wall-disassembly-and-chilling-tolerance-in-cold-stored-peach-fruit
#16
Shifeng Cao, Kun Bian, Liyu Shi, Hsiao-Hang Chung, Wei Chen, Zhenfeng Yang
Melatonin reportedly increased chilling tolerance in postharvest peach fruit during cold storage but information on its effect on cell wall disassembly in chilling injured peaches is limited. In this study, we investigated the role of cell wall depolymerization in chilling tolerance induction in melatonin-treated peaches. Treatment with melatonin at 100 µM alleviated chilling symptom (mealiness) characterized by decrease in fruit firmness and increase in juice extractability in treated peaches during storage...
May 21, 2018: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/29781007/inorganic-janus-nanosheets-bearing-two-types-of-covalently-bound-organophosphonate-groups-via-regioselective-surface-modification-of-k-4-nb-6-o-17-%C3%A2-3h-2-o
#17
Ryoko Suzuki, Mitsuhito Sudo, Megumi Hirano, Naokazu Idota, Masashi Kunitake, Taisei Nishimi, Yoshiyuki Sugahara
Janus nanosheets were prepared from K4Nb6O17·3H2O by modifying surfaces of their two distinct interlayers in a regioselective and sequential manner and subsequent exfoliation. The surface properties of nanosheets were investigated by phase atomic force microscopy imaging and two types of surfaces were discriminated, indicating that Janus nanosheets were successfully prepared.
May 21, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29780473/understanding-the-charge-transport-properties-of-redox-active-metal-organic-conjugated-wires
#18
Donglei Bu, Yingqi Xiong, Ying Ning Tan, Miao Meng, Paul J Low, Dai-Bin Kuang, Chun Y Liu
Layer-by-layer assembly of the dirhodium complex [Rh2 (O2 CCH3 )4 ] (Rh2 ) with linear N , N '-bidentate ligands pyrazine (LS ) or 1,2-bis(4-pyridyl)ethene (LL ) on a gold substrate has developed two series of redox active molecular wires, (Rh2 LS ) n @Au and (Rh2 LL ) n @Au ( n = 1-6). By controlling the number of assembling cycles, the molecular wires in the two series vary systematically in length, as characterized by UV-vis spectroscopy, cyclic voltammetry and atomic force microscopy. The current-voltage characteristics recorded by conductive probe atomic force microscopy indicate a mechanistic transition for charge transport from voltage-driven to electrical field-driven in wires with n = 4, irrespective of the nature and length of the wires...
April 14, 2018: Chemical Science
https://www.readbyqxmd.com/read/29778476/glycation-of-whey-protein-with-dextrans-of-different-molar-mass-effect-on-immunoglobulin-e-binding-capacity-with-blood-sera-obtained-from-patients-with-cow-milk-protein-allergy
#19
Lei Xu, Yuansheng Gong, James E Gern, Shinya Ikeda, John A Lucey
A growing concern around the world is the number of people who are suffering from food protein allergies. One potential approach to decrease protein allergenicity is to block IgE-binding epitopes of the protein allergen by attachment of polysaccharides via the Maillard reaction (i.e., glycation). Protein glycation has been extensively studied to modify various functional properties. We wanted to examine whether glycates could reduce IgE binding in patients with cow milk protein allergy and to explore how the size (molar mass; MW ) of the polysaccharide affects this IgE-binding capacity...
May 16, 2018: Journal of Dairy Science
https://www.readbyqxmd.com/read/29776548/a-label-free-electrochemical-biosensor-for-direct-detection-of-rack-1-by-using-disposable-low-cost-and-reproducible-ito-based-electrode
#20
Hakan Törer, Elif Burcu Aydın, Mustafa Kemal Sezgintürk
In this study we designed an ultrasensitive electrochemical immunosensor for RACK 1 detection using 11-cyanoundecyltrimethoxysilane (11-CUTMS) as a immobilization matrix to immobilize biorecognition element. The used silane agent (11-CUTMS) provides a favorable platform for efficient loading of anti-RACK 1 antibody. The effective loading of the biorecognition element on the 11-CUTMS matrix was monitored by scanning electron microscopy (SEM), atomic force microscopy (AFM) images and fourier transform infrared spectroscopy (FTIR) spectra...
September 18, 2018: Analytica Chimica Acta
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