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https://www.readbyqxmd.com/read/28430192/a-monodisperse-transmembrane-%C3%AE-helical-peptide-barrel
#1
Kozhinjampara R Mahendran, Ai Niitsu, Lingbing Kong, Andrew R Thomson, Richard B Sessions, Derek N Woolfson, Hagan Bayley
The fabrication of monodisperse transmembrane barrels formed from short synthetic peptides has not been demonstrated previously. This is in part because of the complexity of the interactions between peptides and lipids within the hydrophobic environment of a membrane. Here we report the formation of a transmembrane pore through the self-assembly of 35 amino acid α-helical peptides. The design of the peptides is based on the C-terminal D4 domain of the Escherichia coli polysaccharide transporter Wza. By using single-channel current recording, we define discrete assembly intermediates and show that the pore is most probably a helix barrel that contains eight D4 peptides arranged in parallel...
May 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28429015/asymmetric-electroosmotic-pumping-across-porous-media-sandwiched-with-perforated-ion-exchange-membranes
#2
A Yaroshchuk, E E Licón, E K Zholkovskiy, M P Bondarenko, T Heldal
To have non-zero net flow in AC electroosmotic pumps, the electroosmosis (EO) has to be non-linear and asymmetric. This can be achieved due to ionic concentration polarization. This is known to occur close to micro-/nano-interfaces provided that the sizes of the nanopores are not too large compared to the Debye screening length. However, operation of the corresponding EO pumps can be quite sensitive to the solution concentration and, thus, unstable in practical applications. Concentration polarization of ion-exchange membranes is much more robust...
April 21, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28426078/an-intravascular-bioartificial-pancreas-device-ibap-with-silicon-nanopore-membranes-snm-for-islet-encapsulation-under-convective-mass-transport
#3
Shang Song, Charles Blaha, Willieford Moses, Jaehyun Park, Nathan Wright, Joey Groszek, William Fissell, Shant Vartanian, Andrew M Posselt, Shuvo Roy
Diffusion-based bioartificial pancreas (BAP) devices are limited by poor islet viability and functionality due to inadequate mass transfer resulting in islet hypoxia and delayed glucose-insulin kinetics. While intravascular ultrafiltration-based BAP devices possess enhanced glucose-insulin kinetics, the polymer membranes used in these devices provide inadequate ultrafiltrate flow rates and result in excessive thrombosis. Here, we report the silicon nanopore membrane (SNM), which exhibits a greater hydraulic permeability and a superior pore size selectivity compared to polymer membranes for use in BAP applications...
April 20, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28426070/controllable-synthesis-of-ferromagnetic-antiferromagnetic-core-shell-nws-with-tunable-magnetic-properties
#4
M Irfan, C J Wang, U Khan, W J Li, X M Zhang, W J Kong, P Liu, C H Wan, Y W Liu, X F Han
Several nanotechnology applications are based on the promising scheme of highly anisotropic magnetic nanomaterials. Using this idea, we investigated the structure, magnetic properties, and interfacial exchange anisotropy effects of the Ni/Cr2O3 and Fe/Cr2O3 core-shell nanowires (NWs) geometry. A template-based strategy was developed to synthesize Ni (Fe)-Cr2O3 core-shell NWs, which combines a wet-chemical route and electrodeposition within the nanopores of the membranes. Structural determination in correlation with magnetic testing shows that the crystalline Cr2O3-nanoshells (NSs) cause an enhanced exchange bias, providing an extra source of anisotropy that leads to their magnetic stability...
April 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28426059/evolution-of-dealloying-induced-strain-in-nanoporous-gold-crystals
#5
Yu-Chen Karen Chen-Wiegart, Ross Harder, David C Dunand, Ian McNulty
We studied the evolution of dealloying-induced strain along the {111} in a Ag-Au nano-crystal in situ, during formation of nanoporous gold at the initial stage of dealloying using Bragg coherent X-ray diffractive imaging. The strain magnitude with maximum probability in the crystal doubled in 10 s of dealloying. Although formation of nano-pores just began at the surface, the greatest strain is located 60-80 nm deep within the crystal. Dealloying induced a compressive strain in this region, indicating volume shrinkage occurred during pore formation...
April 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28425518/dynamic-manipulation-of-the-local-ph-within-a-nanopore-triggered-by-surface-induced-phase-transition
#6
Akira Koyama, Kazuhiro Fukami, Yujin Imaoka, Atsushi Kitada, Tetsuo Sakka, Takeshi Abe, Kuniaki Murase, Masahiro Kinoshita
Manipulating the local pH within nanoconfinement is essential in nanofluidics technology and its applications. Since the conventional strategy utilizes the overlapping of an electric double layer formed for charge compensation by protons near a negatively charged pore-wall surface, pH variation within a pore is limited to the acidic side. To achieve the variation at the alkaline side, we developed a system comprising a hydrophobic pore-wall surface and aqueous solution containing hydrophobic cations. Beyond a threshold cation concentration, a nanopore is filled with the second phase where the cations are remarkably enriched due to surface-induced phase transition (SIFT) originating from the hydrophobic effect...
April 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28425293/cosensitized-porphyrin-system-for-high-performance-solar-cells-with-tof-sims-analysis
#7
Wenjun Wu, Huaide Xiang, Wei Fan, Jinglin Wang, Haifeng Wang, Xin Hua, Zhaohui Wang, Yi-Tao Long, He Tian, Wei-Hong Zhu
Up to date, development of organic sensitizers has been predominately focused on light harvesting, HOMO and LUMO energy levels, and electron transferring process. In contrast, their adsorption mode as well as dynamic loading behaviour onto nanoporous TiO2 is rarely considered. Herein we have employed the time of flight secondary ion mass spectrometry (TOF-SIMS) to take insight into the competitive dye adsorption mode and kinetics in cosensitized porphyrin system. Using the novel porphyrin dye FW-1 and D-A-π-A featured dye WS-5, the different bond-breaking mode in TOF-SIMS and dynamic dye-loading amount during the coadsorption process are well compared with two different anchoring groups such as benzoic acid and cyanoacrylic acid...
April 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28424207/a-distributed-solute-model-an-extended-two-pore-model-with-application-to-the-glomerular-sieving-of-ficoll
#8
Carl M Öberg, Joseph J Groszek, Shuvo Roy, William H Fissell, Bengt Rippe
One of the many unresolved questions regarding the permeability of the glomerular filtration barrier is the reason behind the marked difference in permeability between albumin and polysaccharide probe molecules such as Ficoll and dextran of the same molecular size. Although the differences in permeability have been mainly attributed to charge effects, we have previously shown that this would require a highly charged filtration barrier, having a charge density that is ~10 times more than that on the albumin molecule...
April 19, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28422400/sequence-specific-covalent-capture-coupled-with-high-contrast-nanopore-detection-of-a-disease-derived-nucleic-acid-sequence
#9
Maryam Imani Nejad, Ruicheng Shi, Xinyue Zhang, Li-Qun Gu, Kent S Gates
Hybridization-based methods for the detection of nucleic acid sequences are important in research and medicine. Short probes provide sequence specificity, but may not provide a durable signal. Sequence-specific covalent cross-link formation can anchor probes to target DNA and also may provide an additional layer of target selectivity. Here we develop a new cross-linking reaction for the covalent capture of specific nucleic acid sequences. This process involves reaction of an abasic site in a probe strand with an adenine residue in the target strand and was used for the detection of a disease-relevant T→A mutation at position 1799 of the human BRAF kinase gene sequence...
April 19, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28422265/nanoporous-poly-3-hexylthiophene-thin-film-structures-from-self-organization-of-a-tunable-molecular-bottlebrush-scaffold
#10
Suk-Kyun Ahn, Jan-Michael Y Carrillo, Jong K Keum, Jihua Chen, David Uhrig, Bradley S Lokitz, Bobby G Sumpter, S Michael Kilbey
The ability to widely tune the design of macromolecular bottlebrushes provides access to self-assembled nanostructures formed by microphase segregation in melt, thin film and solution that depart from structures adopted by simple linear copolymers. A series of random bottlebrush copolymers containing poly(3-hexylthiophene) (P3HT) and poly(d,l-lactide) (PLA) side chains grafted on a poly(norbornene) backbone were synthesized via ring-opening metathesis polymerization (ROMP) using the grafting through approach...
April 19, 2017: Nanoscale
https://www.readbyqxmd.com/read/28422203/a-nanoporous-ag-i-coordination-polymer-for-selective-adsorption-of-carcinogenic-dye-acid-red-26
#11
Cheng-Peng Li, Hang Zhou, Si Wang, Hong-Han Yuan, Su-Zhen Zhang, Miao Du
A cationic Ag(i) coordination polymer with 1D nanoporous channels (ca. 1.22 nm diameter) shows the selective and complete removal of carcinogenic dye Acid Red 26 from aqueous solution upon the size-exclusion and charge-matching effect.
April 19, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28422171/nanoporous-microsphere-assembly-of-iodine-functionalised-silver-nanoparticles-as-a-novel-mini-substrate-for-enriching-and-sensing
#12
X-L Wu, H Wu, Z-M Wang, H Aizawa, J Guo, Y-H Chu
Herein, debris particulates of nanoporous silver (np-Ag) were synthesised by a dealloying method, and their integration behaviour and surface-enhanced Raman scattering (SERS) properties during iodine functionalisation were examined. It was found that the dealloyed np-Ag debris particulates gradually assembled to form rigid nanoporous microspheres comprising Ag nano-ligaments due to mechanical collisions during iodine treatment. High-resolution transmission electron microscopy and X-ray photoelectron microscopy clearly showed the iodide surface of np-Ag, which was dotted with iodine or iodide 'nanoislands'...
April 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28421749/design-of-multi-functional-nanogate-in-response-to-multiple-external-stimuli-using-amphiphilic-diblock-copolymer
#13
Kai Huang, Igal Szleifer
Nature uses the interplay between hydrophobic and electrostatic interactions of disordered proteins to orchestrate complicated molecular gate such as the nuclear pore complex to control the transport of biological masses. Inspired by nature, we here theoretically show that well-defined gate shape, sensitive response to pH and salt concentration, and selectivity in cargo transport can be simultaneously achieved by grafting amphiphilic diblock copolymers made of sequence-controlled hydrophobic and ionizable monomers on the inner surface of solid-state nanopore...
April 19, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28418651/electrodeposition-of-highly-porous-pt-nanoparticles-studied-by-quantitative-3d-electron-tomography-influence-of-growth-mechanisms-and-potential-cycling-on-the-active-surface-area
#14
Jon Ustarroz, Bart Geboes, Hans Vanrompay, Kadir Sentosun, Sara Bals, Tom Breugelmans, Annick Hubin
Nanoporous Pt nanoparticles (NPs) are promising fuel cell catalysts due to their large surface area and increased electrocatalytic activity towards the oxygen reduction reaction (ORR). Herein, we report on the influence of the growth mechanisms on the surface properties of electrodeposited Pt dendritic NPs with large surface areas. The electrochemically active surface was studied by hydrogen underpotential deposition (H UPD) and compared for the first time to high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) quantitative 3D electron tomography of individual nanoparticles...
April 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28418201/chemoinformatics-at-ifp-energies-nouvelles-applications-in-the-fields-of-energy-transport-and-environment
#15
REVIEW
Benoit Creton
The objective of the present paper is to summarize chemoinformatics based research, and more precisely, the development of quantitative structure property relationships performed at IFP Energies nouvelles (IFPEN) during the last decade. A special focus is proposed on research activities performed in the "Thermodynamics and Molecular Simulation" department, i. e. the use of multiscale molecular simulation methods in responses to projects. Molecular simulation techniques can be envisaged to supplement dataset when experimental information lacks, thus the review includes a section dedicated to molecular simulation codes, development of intermolecular potentials, and some of their possible applications...
April 18, 2017: Molecular Informatics
https://www.readbyqxmd.com/read/28417122/frequency-control-of-protein-translocation-across-an-oscillating-nanopore
#16
Fabio Cecconi, Muhammad Adnan Shahzad, Umberto Marini Bettolo Marconi, Angelo Vulpiani
The translocation of a lipid binding protein (LBP) is studied using a phenomenological coarse-grained computational model that simplifies both chain and pore geometry. We investigated via molecular dynamics the interplay between transport and unfolding in the presence of a nanopore whose section oscillates periodically in time with a frequency ω, a motion often referred to as the radial breathing mode (RBM). We found that the LPB when mechanically pulled into the vibrating nanopore exhibits a translocation dynamics that in some frequency range is accelerated and shows a frequency locking to the pore dynamics...
April 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28416888/tailoring-pore-size-and-chemical-interior-of-near-1-nm-sized-pores-in-a-nanoporous-polymer-based-on-a-discotic-liquid-crystal
#17
Subham Bhattacharjee, Jody A M Lugger, Rint P Sijbesma
A triazine based disc shaped molecule with two hydrolyzable units, imine and ester groups, was polymerized via acyclic diene metathesis in the columnar hexagonal (Colhex) LC phase. Fabrication of a cationic nanoporous polymer (pore diameter ∼1.3 nm) lined with ammonium groups at the pore surface was achieved by hydrolysis of the imine linkage. Size selective aldehyde uptake by the cationic porous polymer was demonstrated. The anilinium groups in the pores were converted to azide as well as phenyl groups by further chemical treatment, leading to porous polymers with neutral functional groups in the pores...
April 11, 2017: Macromolecules
https://www.readbyqxmd.com/read/28415504/in-vitro-evaluation-of-hydroxyapatite-coatings-with-002-crystallographic-texture-deposited-by-micro-plasma-spraying
#18
Yiming Wang, Xiaomei Liu, Tingting Fan, Zhen Tan, Zheng Zhou, Dingyong He
Hydroxyapatite (HA) coatings are usually deposited on the metallic implant to increase the biocompatibility and protect the bloodstream from harmful metal ions. Atmospheric plasma spray (APS) is known as a cost effective deposition method. However, the low crystallinity of APS deposited coating accelerates its dissolution in body fluid. We used micro-plasma spray (MPS) to develop chemically stable HA coatings, and performed APS as reference. Results showed that MPS deposited coatings exhibited (002) crystallographic texture while the reference sample did not...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28415486/surface-modification-of-thin-film-composite-membrane-by-nanoporous-titanate-nanoparticles-for-improving-combined-organic-and-inorganic-antifouling-properties
#19
D Emadzadeh, M Ghanbari, W J Lau, M Rahbari-Sisakht, D Rana, T Matsuura, B Kruczek, A F Ismail
In this study, nanoporous titanate (NT) nanoparticle synthesized by the solvothermal method was used to modify polyamide layer of thin film composite membranes with the aim of improving membrane resistances against organic and inorganic fouling. Thin film nanocomposite membranes (NMs) were synthesized by adding mNTs (modified nanoparticles) into polyamide selective layer followed by characterization using different analytical instruments. The results of XPS and XRD confirmed the presence of mNTs in the polyamide layer of NMs, while FESEM, AFM, zeta potential and contact angle measurement further supported the changes in physical and chemical properties of the membrane surface upon mNTs incorporation...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28415458/nanopatterned-polystyrene-b-poly-acrylic-acid-surfaces-to-modulate-cell-material-interaction
#20
Erlantz Lizundia, Míriam Sáenz-Pérez, David Patrocinio, Iskander Aurrekoetxea, Maria dM Vivanco, José Luis Vilas
In this work we explore the effect of surface nanoarchitecture of polystyrene (PS) and polystyrene-b-poly(acrylic acid) (PS-b-PAA) diblock copolymer films on cell viability. PS and PS-b-PAA have been nanopatterned at temperatures of 110, 120 and 140°C using nanoporous aluminium oxide membranes (AAO) as a template. Surface architecture strongly depends on the infiltration temperature and the nature of the infiltrated polymer. High patterning temperatures yield hollow fibre shape architecture at the nanoscale level, which substantially modifies the surface hydrophobicity of the resulting materials...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
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