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https://www.readbyqxmd.com/read/28646758/thermo-responsive-diblock-and-triblock-cationic-copolymers-at-the-silica-aqueous-interface-a-qcm-d-and-afm-study
#1
Saeed Zajforoushan Moghaddam, Kaizheng Zhu, Bo Nyström, Esben Thormann
The properties of synthesized diblock poly(N-isopropylacrylamide)-poly((3-acrylamidopropyl)trimethylammonium chloride) and triblock methoxy-poly(ethylene glycol)-poly(N-isopropylacrylamide)-poly((3-acrylamidopropyl)trimethylammonium chloride) cationic copolymers at the silica/aqueous interface are investigated using quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). Moreover, dynamic light scattering is employed to assess the copolymers in terms of the hydrodynamic size and interchain aggregation...
June 15, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28646437/cytotoxic-and-genotoxic-effects-of-silver-nanoparticle-carboxymethyl-cellulose-on-allium-cepa
#2
Aline A Becaro, Maria Célia Siqueira, Fernanda C Puti, Marcia Regina de Moura, Daniel S Correa, José Manoel Marconcini, Luiz H C Mattoso, Marcos David Ferreira
Several mutagenic agents may be present in substances released in the environment, which may cause serious environmental impacts. Among these substances, there is a special concern regarding the widespread use of silver nanoparticles (AgNP) in several products due to their widely known bactericidal properties, including in the medical field and the food industry (e.g., active packaging). The assessment of the effects of AgNP released in the environment, having different concentrations, sizes, and being associated or not to other types of materials, including polymers, is therefore essential...
July 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28646435/eco-friendly-synthesis-of-silver-nanoparticles-using-green-algae-caulerpa-serrulata-reaction-optimization-catalytic-and-antibacterial-activities
#3
Eman F Aboelfetoh, Rania A El-Shenody, Mohamed M Ghobara
Stable colloidal silver nanoparticles (AgNPs) were synthesized using Caulerpa serrulata (green marine algae) aqueous extract as an efficient reducing and stabilizing agent. This method is considered to be a sustainable alternate to the more complicated chemical procedures. To achieve the optimization synthesis of AgNPs, several effects such as extract concentration, contact time, pH values, and temperature were examined. The synthesized AgNPs were characterized by UV-Vis spectroscopy, FT-IR, XRD, and HR-TEM...
July 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28645045/hydra-amphiphiles-using-three-heads-and-one-tail-to-influence-aggregate-formation-and-to-kill-pathogenic-bacteria
#4
Tara M Gallagher, John N Marafino, Brenden K Wimbish, Brandi Volkers, Gabriel Fitzgerald, Kristin McKenna, Jason Floyd, Nicholas T Minahan, Brenna Walsh, Kirstie Thompson, David Bruno, Monica Paneru, Sybelle Djikeng, Stephanie Masters, Suma Haji, Kyle Seifert, Kevin L Caran
Hydra amphiphiles mimic the morphology of the mythical multi-headed creatures for which they are named. Likewise, when faced with a pathogenic bacterium, some hydra derivatives are as destructive as their fabled counterparts were to their adversaries. This report focuses on eight new tricephalic (triple-headed), single-tailed amphiphiles. Each amphiphile has a mesitylene (1,3,5-trimethylbenzene) core, two benzylic trimethylammonium groups and one dimethylalkylammonium group with a linear hydrophobe ranging from short (C8H17) to ultralong (C22H45)...
June 10, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28645036/influence-of-surface-states-on-blinking-characteristics-of-single-colloidal-cdse-cds-zns-core-multishell-quantum-dot
#5
Hao Xu, Hjalmar Brismar, Ying Fu
We carefully characterized the fluorescence blinking of single colloidal CdSe-CdS/ZnS core-multishell quantum dots (QDs) with different surface modifications, including octadecylamine (ODA) coated QDs dispersed in chloroform, aqueous 3-mercaptopropionic acids (3MPA) coated QDs in HEPES solution treated by Ca(2+) ions and ethylene glycol tetraacetic acid (EGTA, Ca(2+) chelator), and aqueous 3MPA-QDs treated by glycerol. It was found that the on- and off-state probability density distributions displayed different rules...
June 16, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28644033/direct-indirect-nature-of-the-bandgap-in-lead-free-perovskite-nanocrystals
#6
Yuhai Zhang, Jun Yin, Manas R Parida, Ghada H Ahmed, Jun Pan, Osman M Bakr, Jean-Luc Bredas, Omar F Mohammed
With record efficiencies achieved in lead halide perovskite-based photovoltaics, urgency has shifted towards finding alternative materials that are stable and less-toxic. Bismuth-based perovskite materials are currently one of the most promising candidates amongst those alternatives. However, the band structures of these materials, including the nature of the bandgaps, remain elusive due to extremely low photoluminescence quantum yield (PLQY) and scattering issues in their thin-film or bulk form. Here, we overcome those limitations and reveal the specific nature of the material's electronic transitions by realizing monodisperse colloidal nanocrystals (NCs) of hexagonal-phase Cs3Bi2X9 perovskites, which afford well-resolved PL features...
June 23, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28644018/the-role-of-the-crystal-structure-in-cation-exchange-reactions-involving-colloidal-cu2se-nanocrystals
#7
Graziella Gariano, Vladimir Lesnyak, Rosaria Brescia, Giovanni Bertoni, Zhiya Dang, Roberto Gaspari, Luca De Trizio, Liberato Manna
Stoichiometric Cu2Se nanocrystals were synthesized in either cubic or hexagonal (metastable) crystal structures and used as the host material in cation exchange reactions with Pb2+ ions. Even if the final product of the exchange, in both cases, was rock-salt PbSe nanocrystals, we show here that the crystal structure of the starting nanocrystals has a strong influence on the exchange pathway. The exposure of cubic Cu2Se nanocrystals to Pb2+ cations led to the initial formation of PbSe unselectively on the overall surface of the host nanocrystals, generating Cu2Se@PbSe core@shell nano-heterostructures...
June 23, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28643833/modelling-critical-casimir-force-induced-self-assembly-experiments-on-patchy-colloidal-dumbbells
#8
Arthur C Newton, T Anh Nguyen, Sandra J Veen, Daniela J Kraft, Peter Schall, Peter G Bolhuis
Colloidal particles suspended in a binary liquid mixture can interact via solvent mediated interactions, known as critical Casimir forces. For anisotropic colloids this interaction becomes directional, which leads to rich phase behavior. While experimental imaging and particle tracking techniques allow determination of isotropic effective potentials via Boltzmann inversion, the modeling of effective interaction in anisotropic systems is non-trivial precisely because of this directionality. Here we extract effective interaction potentials for non-spherical dumbbell particles from observed radial and angular distributions, by employing reference interaction site model (RISM) theory and direct Monte Carlo simulations...
June 23, 2017: Soft Matter
https://www.readbyqxmd.com/read/28641543/zein-based-nanocarriers-as-potential-natural-alternatives-for-drug-and-gene-delivery-focus-on-cancer-therapy
#9
Ahmed Elzoghby, May Freag, Hadeer Mamdouh, Kadria Elkhodairy
Protein nanocarriers possess unique merits including minimal cytotoxicity, numerous renewable sources, and high drug-binding capability. In opposition to delivery carriers utilizing hydrophilic animal proteins, hydrophobic plant proteins (e.g, zein) have great tendency in fabricating controlled-release particulate carriers without additional chemical modification to stiffen them, which in turn evades the use of toxic chemical crosslinkers. Moreover, zein is related to a class of alcohol-soluble prolamins and generally recognized as safe (GRAS) carrier for drug delivery...
June 22, 2017: Current Pharmaceutical Design
https://www.readbyqxmd.com/read/28641424/the-role-of-multivalency-in-the-association-kinetics-of-patchy-particle-complexes
#10
Arthur C Newton, Jan Groenewold, Willem K Kegel, Peter G Bolhuis
Association and dissociation of particles are elementary steps in many natural and technological relevant processes. For many such processes, the presence of multiple binding sites is essential. For instance, protein complexes and regular structures such as virus shells are formed from elementary building blocks with multiple binding sites. Here we address a fundamental question concerning the role of multivalency of binding sites in the association kinetics of such complexes. Using single replica transition interface sampling simulations, we investigate the influence of the multivalency on the binding kinetics and the association mechanism of patchy particles that form polyhedral clusters...
June 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28641183/size-partitioning-and-mixing-behavior-of-trace-metals-and-dissolved-organic-matter-in-a-south-china-estuary
#11
Wenhao Wang, Min Chen, Laodong Guo, Wen-Xiong Wang
The Jiulong River estuary, located in the southeastern China, suffered from metal pollution due to industrial effluent releases. Mixing of effluent and estuarine water may have significantly affected the size distribution of trace metals and their environmental fate. In the present study, colloidal size distribution of organic matter and selected metals were quantified using asymmetric flow field-flow fractionation (AF4) and ICP-MS. We demonstrated a dominance of dissolved metals in the 1-10kDa fraction, and metals such as Cu, Zn, Ni, Co, Pb, Cd and Mn were mostly regulated by terrestrial fulvic acid...
June 19, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28641182/unraveling-the-complexities-of-the-velocity-dependency-of-e-coli-retention-and-release-parameters-in-saturated-porous-media
#12
Salini Sasidharan, Scott A Bradford, Saeed Torkzaban, Xueyan Ye, Joanne Vanderzalm, Xinqiang Du, Declan Page
Escherichia coli transport and release experiments were conducted to investigate the pore-water velocity (v) dependency of the sticking efficiency (α), the fraction of the solid surface area that contributed to retention (Sf), the percentage of injected cells that were irreversibly retained (Mirr), and cell release under different (10-300mM) ionic strength (IS) conditions. Values of α, Sf, and Mirr increased with increasing IS and decreasing v, but the dependency on v was greatest at intermediate IS (30 and 50mM)...
June 19, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28641089/combined-time-lapse-magnetic-resonance-imaging-and-modeling-to-investigate-colloid-deposition-and-transport-in-porous-media
#13
Alizée P Lehoux, Pamela Faure, François Lafolie, Stéphane Rodts, Denis Courtier-Murias, Philippe Coussot, Eric Michel
Colloidal particles can act as vectors of adsorbed pollutants in the subsurface, or be themselves pollutants. They can reach the aquifer and impair groundwater quality. The mechanisms of colloid transport and deposition are often studied in columns filled with saturated porous media. Time-lapse profiles of colloid concentration inside the columns have occasionally been derived from magnetic resonance imaging (MRI) data recorded in transport experiments. These profiles are valuable, in addition to particle breakthrough curves (BTCs), for testing and improving colloid transport models...
June 14, 2017: Water Research
https://www.readbyqxmd.com/read/28640995/colloidal-gold-nanoparticles-induce-changes-in-cellular-and-subcellular-morphology
#14
Xiaowei Ma, Raimo Hartmann, Dorleta Jimenez de Aberasturi, Fang Yang, Stefaan J H Soenen, Bella B Manshian, Jonas Franz, Daniel Valdeperez, Beatriz Pelaz, Neus Feliu, Norbert Hampp, Christoph Riethmüller, Henning Vieker, Natalie Frese, Armin Gölzhäuser, Michael Simonich, Robert L Tanguay, Xing-Jie Liang, Wolfgang J Parak
Exposure of cells to colloidal nanoparticles (NPs) can have concentration-dependent harmful effects. Mostly, such effects are monitored with biochemical assays or probes from molecular biology, i.e. viability assays, gene expression profiles, etc., neglecting that the presence of NPs can also drastically affect cellular morphology. In the case of polymer-coated Au NPs we demonstrate that upon NP internalization, cells undergo lysosomal swelling, alterations in mitochondrial morphology, disturbances in actin and tubulin cytoskeleton and associated signaling, and reduction of focal adhesion contact area and number of filopodia...
June 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28640019/mini-fluid-challenge-of-100-ml-of-crystalloid-predicts-fluid-responsiveness-in-the-operating-room
#15
Matthieu Biais, Hugues de Courson, Romain Lanchon, Bruno Pereira, Guillaume Bardonneau, Marion Griton, Musa Sesay, Karine Nouette-Gaulain
BACKGROUND: Mini-fluid challenge of 100 ml colloids is thought to predict the effects of larger amounts of fluid (500 ml) in intensive care units. This study sought to determine whether a low quantity of crystalloid (50 and 100 ml) could predict the effects of 250 ml crystalloid in mechanically ventilated patients in the operating room. METHODS: A total of 44 mechanically ventilated patients undergoing neurosurgery were included. Volume expansion (250 ml saline 0...
June 21, 2017: Anesthesiology
https://www.readbyqxmd.com/read/28638903/adsorption-versus-aggregation-of-nipam-nanogels-new-insight-into-their-behaviour-at-the-air-water-interface-as-a-function-of-concentration
#16
Katarzyna Zielińska, Richard A Campbell, Ali Zarbakhsh, Marina Resmini
We have used neutron reflectivity (NR) measurements in combination with dynamic light scattering (DLS), surface tension and ellipsometry, to study the adsorption behaviour at the air/water interface of N-isopropylacrylamide-based nanogels as a function of concentration. The data provide clear evidence that the nanogels are adsorbed at the interface in a strongly deformed shape and forming a multi-layer where the thickness increases with nanogel concentration in the bulk. The combination of surface characterisation techniques and bulk studies indicate that interfacial film formation is preferred over bulk aggregation...
June 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28638177/highly-luminescent-water-dispersible-nir-emitting-wurtzite-cuins2-zns-core-shell-colloidal-quantum-dots
#17
Chenghui Xia, Johannes D Meeldijk, Hans C Gerritsen, Celso de Mello Donega
Copper indium sulfide (CIS) quantum dots (QDs) are attractive as labels for biomedical imaging, since they have large absorption coefficients across a broad spectral range, size- and composition-tunable photoluminescence from the visible to the near-infrared, and low toxicity. However, the application of NIR-emitting CIS QDs is still hindered by large size and shape dispersions and low photoluminescence quantum yields (PLQYs). In this work, we develop an efficient pathway to synthesize highly luminescent NIR-emitting wurtzite CIS/ZnS QDs, starting from template Cu2-x S nanocrystals (NCs), which are converted by topotactic partial Cu(+) for In(3+) exchange into CIS NCs...
June 13, 2017: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/28636398/ultrafast-carrier-trapping-in-thick-shell-colloidal-quantum-dots
#18
Ankit Jain, Oleksandr Voznyy, Marek Korkusinski, Pawel Hawrylak, Edward H Sargent
It has previously been found that Auger processes can lead to femtosec- ond carrier trapping in quantum dots, limiting their performance in opto- electronic applications that rely on radiative recombination. Here, using atomistic simulations, we investigate whether a shell can protect carriers from Auger-assisted trapping. For these studies we investigate CdSe/CdS core-shell quantum dots having total diameters reaching up to 10 nm. We find trapping lifetimes as fast as 1 ps for 2 nm shells, and we report that shells as thick as 6 nm are required to suppress trapping fully...
June 21, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28636318/inverse-photonic-glasses-by-packing-bi-disperse-hollow-microspheres-with-uniform-cores
#19
Seung-Hyun Kim, Sofia Magkiriadou, Do Kyung Rhee, Doo Sung Lee, Pil J Yoo, Vinothan N Manoharan, Gi-Ra Yi
A major fabrication challenge is producing disordered photonic materials with angle-independent structural red color. Theoretical work has shown that such color can be produced by fabricating inverse photonic glasses with monodisperse, non-touching voids in a silica matrix. Here we demonstrate a route toward such materials and show that they have angle-independent red color. We first synthesize monodisperse hollow silica particles with precisely controlled shell thickness, then make glassy colloidal structures by mixing two types of hollow particles with the same core size and different shell thicknesses...
June 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28635413/the-high-responder-a-review-of-pathophysiology-and-outcomes-during-ivf-treatment
#20
Mariano Mascarenhas, Adam H Balen
This review attempts to summarize the known literature on high responders to ovarian stimulation during assisted reproductive techniques (ART). Response to gonadotrophins is subject to significant interindividual and intercycle variation, thus carrying a risk of high response or poor response to ovarian stimulation regimens. The main risk for high responders is the development of ovarian hyperstimulation syndrome (OHSS) which is associated with significant morbidity. Hence, the definition of high responders in the literature has primarily focussed on risk factors for OHSS...
February 28, 2017: Human Fertility: Journal of the British Fertility Society
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