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Polyelectrolyte

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https://www.readbyqxmd.com/read/30514188/control-of-aggregation-coaggregation-and-liquid-droplet-of-proteins-using-small-additives
#1
Kazuki Iwashita, Masahiro Mimura, Kentaro Shiraki
This review article presents the concepts of aggregates, coaggregates, and liquid droplet of proteins and compares the concentrated states in the presence of small additives to control their formation and dissociation. The aggregates composed of single protein molecules result mainly from hydrophobic interactions between unfolded protein molecules. Thus, the aggregation of protein can be effectively suppressed by small additives that increase the solubility of hydrophobic solutes, typically arginine (Arg) and chaotropes...
December 3, 2018: Current Pharmaceutical Biotechnology
https://www.readbyqxmd.com/read/30513320/alginate-based-delivery-systems-for-bevacizumab-local-therapy-in-vitro-stuctural-features-and-release-properties
#2
Natália Noronha Ferreira, Bruno Leonardo Caetano, Fernanda Isadora Boni, Flávia Sousa, Marina Magnani, Bruno Sarmento, Beatriz Stringhetti Ferreira Cury, Maria Palmira Daflon Gremião
Alginate-based polyelectrolytes complexes (PECs) and hydrogel were engineered as platforms for local bevacizumab (BVZ) therapy. This study provides deep comprehension on the microstructures of such systems, and their correlation with drug release patterns. PECs and hydrogel were characterized using Fourier transform infrared spectroscopy (FTIR), small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and porosimetry. Structural investigations indicated that PECs are formed by supramolecular interactions, resulting in physically crosslinked polymer networks, while the bevacizumab-loaded hydrogel has a more compact and rigid structure, promoting better entrapment of BVZ...
December 1, 2018: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/30511865/thermodynamics-of-the-air-water-interface-of-mixtures-of-surfactants-with-polyelectrolytes-oligoelectrolytes-and-multivalent-metal-electrolytes
#3
Robert K Thomas, Jeffrey Penfold
A full comparison of results from binding isotherms and surface tension (ST) measurements on polyelectrolyte (PE)-surfactant (S) mixtures, especially the polymer dependence, shows up clear distinctions between the behaviour of two representative PE-S systems, poly(sodium styrenesulfonate) (NaPSS) with dodecyltrimethylammonium bromide (C12 TAB) and poly(dimethyl-diallyl-ammonium chloride) (PDMDAAC) with sodium dodecylsulfate (SDS) in 100 mM NaCl. The surfactant-monomer binding constant in NaPSS-C12 TAB is an order of magnitude greater than that in the PDMDAAC-SDS system...
December 4, 2018: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/30511062/layer-by-layer-deposition-of-chitosan-nanoparticles-as-drug-release-coatings-for-pcl-nanofibers
#4
Steffen Sydow, Dominik de Cassan, Robert Hänsch, Thomas R Gengenbach, Christopher D Easton, Helmut Thissen, Henning Menzel
Nanogels were prepared by ionotropic gelation of chitosan (CS) with tripolyphosphate (TPP). The use of such nanogels to prepare coatings by layer-by-layer deposition (LbL) was studied. The nanogels were characterized in terms of particle size, zeta-potential and stability. Nanogel suspensions were used to build polyelectrolyte multilayers on silicon wafers and on PCL fiber mats by LbL-deposition. Three different polysaccharides were used as polyanions, namely chondroitin sulfate, alginate and hyaluronic acid...
December 4, 2018: Biomaterials Science
https://www.readbyqxmd.com/read/30500521/encapsulation-of-ciprofloxacin-within-modified-xanthan-gum-chitosan-based-hydrogel-for-drug-delivery
#5
Demiana H Hanna, Gamal R Saad
The aim of the present work was to investigate the preparation of polyelectrolyte hydrogel as potential drug carrier for antibacterial Ciprofloxacin drug (CFX), intended for controlled release formulation. Hydrogel of N-trimehtyl chitosan (TMC)/sodium carboxymethyl xanthan gum (CMXG) was prepared and ciprofloxacin was employed as a model drug to investigate the loading and release performance of the prepared hydrogel. FTIR, DSC, TGA and SEM analysis were used to characterize the TMC/CMXG hydrogel and its CFX loaded hydrogel...
November 22, 2018: Bioorganic Chemistry
https://www.readbyqxmd.com/read/30487401/effect-of-polyelectrolyte-mono-and-bilayer-formation-on-the-colloidal-stability-of-layered-double-hydroxide-nanoparticles
#6
Zoltán Somosi, Marko Pavlovic, István Pálinkó, István Szilágyi
Sequential adsorption of polyelectrolytes on nanoparticles is a popular method to obtain thin films after deposition. However, the effect of polyelectrolyte multilayer formation on the colloidal stability of the nanoparticles has not been studied in detail. In the present work, layered double hydroxides (LDH) were synthesized and interaction with oppositely and like-charged polyelectrolytes was investigated. Electrophoretic and light scattering measurements revealed that colloidal stability of LDH can be tuned by adsorption of poly(styrene sulfonate) (PSS) on the oppositely charged LDH surface in appropriate doses and thus, unstable or stable dispersions can be designed...
November 28, 2018: Nanomaterials
https://www.readbyqxmd.com/read/30486979/oral-delivery-of-pingyangmycin-by-layer-by-layer-lbl-self-assembly-polyelectrolyte-grafted-nano-graphene-oxide
#7
Yu Liu, Jiajing Han, Hao Pan, Dechao Jia, Lijiang Chen, Xiaoyang Yang
With the increasing development in scientific technology, building a nanocarrier system for cancer drugs has become a bliss for cancer patients. To allow for the oral administration of hydrophilic drugs, a nanocarrier that was based on negatively charged graphene oxide (GO) and prepared through the Layer-by-Layer (LbL) self-assembly of poly(acrylic acid)-cysteine (PAA-cys) and poly(allylamine hydrochloride) (PAH) was established. In the present study, we demonstrated the excellent biological properties of GO, the biological adhesiveness of PAA-cys, and the protection and controlled release profiles of polyelectrolyte...
April 1, 2019: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/30486501/manipulation-of-p-n-type-thermoelectric-thin-films-through-a-layer-by-layer-assembled-carbonaceous-multilayer-structure
#8
Wonjun Jang, Hyun A Cho, Kyungwho Choi, Yong Tae Park
Recently, with the miniaturization of electronic devices, problems with regard to the size and capacity of batteries have arisen. Energy harvesting is receiving significant attention to solve these problems. In particular, the thermoelectric generator (TEG) is being studied for its ability to harvest waste heat energy. However, studies on organic TEGs conducted thus far have mostly used conductive polymers, making the application range of TEGs relatively narrow. In this study, we fabricated organic TEGs using carbonaceous nanomaterials (i...
November 28, 2018: Micromachines
https://www.readbyqxmd.com/read/30481539/thermodynamics-and-site-stoichiometry-of-dna-binding-by-a-large-antiviral-hairpin-polyamide
#9
Yang Song, Jacquelyn Niederschulte, Kristin N Bales, James K Bashkin, Cynthia M Dupureur
PA1: (dIm-PyPyβPyPyPy-γ-PyPyβPyPyPyPyβ-Ta) is a large (14-ring) hairpin polyamide that was designed to recognize the DNA sequence 5'-W2 GW7 -3', where W is either A or T. As is common among the smaller 6-8-ring hairpin PAs, it binds its target recognition sequence with low nM affinity. However, in addition to its large size, it is distinct from these more extensively characterized in its high tolerance for mismatches and antiviral properties. In ongoing attempts to understand the basis for these distinctions, we conducted thermodynamics studies of PA1-DNA interactions...
November 24, 2018: Biochimie
https://www.readbyqxmd.com/read/30476882/surface-regeneration-and-reusability-of-label-free-dna-biosensors-based-on-weak-polyelectrolyte-modified-capacitive-field-effect-structures
#10
Thomas S Bronder, Arshak Poghossian, Max P Jessing, Michael Keusgen, Michael J Schöning
The reusability of capacitive field-effect electrolyte-insulator-semiconductor (EIS) sensors modified with a cationic weak polyelectrolyte (poly(allylamine hydrochloride) (PAH)) for the label-free electrical detection of single-stranded DNA (ssDNA), in-solution- and on-chip-hybridized double-stranded DNA (dsDNA) has been studied. It has been demonstrated that via simply regeneration of the gate surface of the EIS sensor by means of an electrostatic adsorption of a new PAH layer, the same biosensor can be reused for at least five DNA-detection measurements...
November 15, 2018: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/30471376/fabrication-of-the-polyphosphates-patched-cellulose-sulfate-chitosan-hydrochloride-microcapsules-and-as-vehicles-for-sustained-drug-release
#11
Ting Su, Qing-Xi Wu, Yan Chen, Jin Zhao, Xiao-Du Cheng, Juan Chen
Polyphosphates are important polyanionic electrolytes that play a major role in stabilization and consolidation of colloids surface and interior microstructures. In this study, the polyelectrolyte complexes (PEC) microcapsules (sodium cellulose sulfate -chitosan hydrochloride, sample 1), and the patched ones via sodium tripolyphosphate (sample 2), sodium pyrophosphate (sample 3) and sodium hexametaphosphate (sample 4) were fabricated under mild conditions. The effects of polyphosphates on the formation of the PEC microcapsules were investigated systematically...
November 21, 2018: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/30469118/voltage-controlled-ion-transport-and-selectivity-in-a-conical-nanopore-functionalized-with-ph-tunable-polyelectrolyte-brushes
#12
Jyh-Ping Hsu, Shu-Tuan Yang, Chih-Yuan Lin, Shiojenn Tseng
Chemically functionalized bioinspired nanopores are widely adopted to control the ionic transport for various purposes. A detailed understanding of the underlying mechanisms is not only desirable but also necessary for device design and experimental data interpretation. Here, the conductance and the ion selectivity of a conical nanopore surface modified by a polyelectrolyte (PE) layer are studied through adjusting the pH, the bulk salt concentration, and the level of the applied potential bias. Possible mechanisms are proposed and discussed in detail...
November 13, 2018: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/30468444/computer-study-of-the-solubilization-of-polymer-chains-in-polyelectrolyte-complex-cores-of-polymeric-nanoparticles-in-aqueous-media
#13
Karel Šindelka, Zuzana Limpouchová, Karel Procházka
The formation and structure of nanoparticles containing non-polar polymer chains solubilized in interpolyelectrolyte complex (IPC) cores and the partitioning of non-polar chains between bulk solvent and IPC cores were studied by coarse-grained computer simulations. The choice of the model system was inspired by experimental results published by van der Burgh et al. (Langmuir, 2004, 20, 1073-1084). The dissipative particle dynamics (DPD) simulations reproduced the structure and basic features of co-assembled nanoparticles described by experimentalists well at the semi-quantitative coarse-grained level and revealed new properties of co-assembled particles...
November 23, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30468390/impact-of-the-solid-interface-on-proton-conductivity-in-nafion-thin-films
#14
Yudai Ogata, Tatsuki Abe, Shigeki Yonemori, Norifumi L Yamada, Daisuke Kawaguchi, Keiji Tanaka
Proton conductivity of polyelectrolytes in the interfacial region with a solid is a key for the performance of polyelectrolyte-based fuel cells. The proton conductivity of Nafion thin films was examined as a function of the thickness along both directions, normal and parallel to the interface. Neutron reflectivity measurements revealed that a water-containing multilamellar structure was formed at the substrate interface. The presence of the interfacial layer, or the two-dimensional proton-conductive pathway, suppressed and enhanced the out-of-plane and in-plane proton conductivity, respectively...
November 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/30466268/a-transport-model-and-constitutive-equation-for-oppositely-charged-polyelectrolyte-mixtures-with-application-to-layer-by-layer-assembly
#15
Ali Salehi, Ronald G Larson
We develop a general framework for transport of polyions, solvent and salt, with intended application to Layer-by-Layer (LbL) assembly of polyelectrolyte monolayers (PEMs). The formulation for the first time includes electrostatics, chemical potential gradients, and mechanical stress gradients as driving forces for mass transport. The general model allows all species to be mobile throughout the process and avoids the assumptions of stepwise instantaneous equilibrium and/or immobilized structures typical of previous approaches, while reducing to these models in appropriate limits...
November 21, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/30457144/tuning-the-collapse-transition-of-weakly-charged-polymers-by-ion-specific-screening-and-adsorption
#16
Richard Chudoba, Jan Heyda, Joachim Dzubiella
The experimentally observed swelling and collapse response of weakly charged polymers to the addition of specific salts displays quite convoluted behavior that is not easy to categorize. Here we use a minimalistic implicit-solvent/explicit-salt simulation model with a focus on ion-specific interactions between ions and a single weakly charged polyelectrolyte to qualitatively explain the observed effects. In particular, we demonstrate ion-specific screening and bridging effects cause collapse at low salt concentrations whereas the same strong ion-specific direct interactions drive re-entrant swelling at high concentrations...
December 5, 2018: Soft Matter
https://www.readbyqxmd.com/read/30453614/development-of-pectin-type-b-gelatin-polyelectrolyte-complex-for-curcumin-delivery-in-anticancer-therapy
#17
Fu-Ying Shih, Ih-Jen Su, Li-Lun Chu, Xiaojie Lin, Sheng-Chu Kuo, Yu-Chi Hou, Yi-Ting Chiang
Curcumin has been proven to be a potent agent in colon cancer treatment. However, its hydrophobicity and low oral bioavailability hampered its clinical application. These limitations could be improved through appropriate formulations such as using polyelectrolyte complexes (PECs). PECs were self-assembled with polycations and polyanions in polar solvents. In this study, a novel pectin-type B gelatin PEC was developed for use in curcumin formulation. At pH 4.0, natural polyanions pectin and polycations type B gelatin spontaneously formed PECs in ethanol/water solution, whereas under mimetic gastrointestinal tract (GI tract) conditions, at pH 2...
November 17, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/30452265/shedding-light-on-the-dark-corners-of-mof-thin-films-growth-and-structural-stability-of-zif-8-layers-probed-by-optical-waveguide-spectroscopy
#18
Juan Alejandro Allegretto, Jakub Dostalek, Matías Rafti, Bernhard Menges, Omar Azzaroni, Wolfgang Knoll
Due to its many features and possible applications, metal-organic frameworks have attracted increasing attention in recent years. Within this type of materials, hydrophobic zeolitic imidazolate framework constituted of Zn2+ metal centers, coordinated by 2-methylimidazolate organic linkers (ZIF-8); has proved to be a highly versatile porous support compatible with diverse applications ranging from sensing platforms to electronics or energy-related devices. However, the study of a crucial parameter such as their structural stability towards exposure to different aqueous environments (relevant for a wide range of applications), remains only partially addressed and constitutes one of the main goals of the present work...
November 19, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/30450523/a-study-of-the-cytotoxic-effect-of-microcapsules-and-their-constituent-polymers-on-macrophages-and-tumor-cells
#19
A A Naumov, A V Dubrovskii, E V Musin, A L Kim, M M Potselueva, S A Tikhonenko
We studied the effect of different concentrations of polyelectrolytes poly(allylamine hydrochloride) (PAH) and polystyrene sulfonate (PSS) as well as the effects of microcapsules coated with these polymers on survival of Ehrlich ascites carcinoma cells and mouse peritoneal macrophages and on ROS production by phagocytes. PAH reduced viability of Ehrlich ascites carcinoma in a concentration-dependent manner (LD50 =12-15 μg/ml). This effect was presumably determined by its ability to bind phosphates, thereby depleting the culture medium...
November 2018: Bulletin of Experimental Biology and Medicine
https://www.readbyqxmd.com/read/30448237/layer-by-layer-adsorption-factors-affecting-the-choice-of-substrates-and-polymers
#20
REVIEW
Iuliia S Elizarova, Paul F Luckham
The electrostatic layer-by-layer technique for fabrication of multi-layered structures of various sizes and shapes using flat and colloidal templates coupled with polyelectrolyte layer-forming materials has attracted significant interest among both academic and industrial researchers due to its versatility and relative simplicity of the procedures involved in its execution. Fabrication of the multi-layered structures using the electrostatic layer-by-layer method involves several distinct stages each of which holds great importance when considering the production of a high-quality product...
December 2018: Advances in Colloid and Interface Science
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