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Guangcan Yang, Yanwei Wang
Dynamic Light Scattering ( DLS ) enables the characterization of sizes and electrokinetic properties of colloids, polymers, macromolecules. DNA is a charged semiflexible polyelectrolyte, which is condensed or compacted by counterions, proteins, and other condensing agents in processes such as chromosome compaction and gene therapeutic applications. DNA condensation is closely related to charge screening, since packaging requires effective neutralization of its surface negative charges. In this chapter, we describe in detail the protocol for DLS of DNA-ligand complexes...
2018: Methods in Molecular Biology
Alexandre Hardy, Cendrine Seguin, Anaïs Brion, Philippe Lavalle, Pierre Schaaf, Sylvie Fournel, Line Bourel-Bonnet, Benoit Frisch, Dr Marcella De Giorgi
Nowadays, the need for therapeutic biomaterials displaying anti-inflammatory properties to fight against inflammation-related diseases is continuously increasing. Compact PolyElectrolyte Complexes (CoPECs) represent a new class of materials obtained by ultracentrifugation of a polyanion/polycation complexes suspension in the presence of salt. Here, a non-cytotoxic β-cyclodextrin-functionalized chitosan/alginate CoPEC was formulated, characterized and described as a promising drug carrier displaying an intrinsic anti-inflammatory property...
August 14, 2018: ACS Applied Materials & Interfaces
Dipak Aryal, Venkat Ganesan
The dynamics of ions and solvent molecules in polyelectrolyte desalination membranes is key to water purification technologies in which selective transport of the different components is desired. Recent experimental and our computational results have shown that nontrivial mechanisms underlie the transport properties of salt ions and water in charged polymer membranes. Explicitly, in polymer electrolytes, we found a reversal in the salt concentration dependence of the mobilities of Na+ , Cl- salt ions and water molecules when compared with aqueous solutions...
August 14, 2018: Journal of Physical Chemistry. B
Junjie Wei, Jie Zhou, Shasha Su, Jinhua Jiang, Jing Feng, Qigang Wang
With the boom of flexible electronic products and wearable devices, flexible energy storage devices, e.g., supercapacitors with high performance, are attracting increasing interest. A flexible water-deactivated polyelectrolyte hydrogel electrolyte with good mechanical properties and high ionic conductivity was prepared using an anionic polymer CMC and a cationic monomer MAPTAC. It was then applied in a supercapacitor with flexible activated carbon electrodes. This flexible supercapacitor possesses a high operating voltage of 2...
August 13, 2018: ChemSusChem
Shohei Shiomoto, Kazuo Yamaguchi, Motoyasu Kobayashi
The microscopic wetting behavior of a water film on the line-patterned surface of a polyelectrolyte brush was directly visualized using an optical microscope by dyeing procedures. Surface line patterns of 5 μm and 5 μm width or 10 μm and 5 μm width for the polyelectrolyte brush and hydrophobic monolayer, respectively, were prepared by a photolithography process, chemical vapor adsorption method, and surface-initiated polymerization. A droplet of water containing dye was placed on the line-patterned surface...
August 13, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Ren Geryak, Elizabeth Quigley, Sunghan Kim, Volodymyr F Korolovych, Rossella Calabrese, David L Kaplan, Vladimir V Tsukruk
Microencapsulation techniques represent a critical step in realizing highly controlled transport of functional materials in multiphase systems. The first demonstration of microcapsules prepared from minimally grafted silk ionomers (silk fibroin modified with cationic/anionic charge groups) are presented here. These tailored biomacromolecules have shown significantly increased biocompatibility over traditional polyelectrolytes and heavily grafted silk ionomers, but the low grafting density had previously limited attempts to fabricate stable microcapsules...
August 13, 2018: Macromolecular Bioscience
Vivekjot Brar, Gurpreet Kaur
OBJECTIVE: Esculin loaded nanoparticles for nasal delivery were prepared by ionic gelation technique using okra gum and chitosan Method: The preparation of nanoparticles was optimized using Box-Behnken experimental design employing particle size, entrapment efficiency and zeta potential as dependable variables. Okra concentration, chitosan concentration, pH and stirring speed were taken as independent variables. RESULTS: The formulations were found to depict particle size in the range of 294...
August 13, 2018: Pharmaceutical Nanotechnology
Cen Lin, Erwin R Stedronsky, Luke R Jordan, Nathan J Wittenberg, Steven L Regen
A plug and socket approach for tightening polyelectrolyte multilayers is introduced based on the use pendant β-cyclodextrin groups. Prototypical multilayers derived from poly(sodium 4-styrene sulfonate) and β-cyclodextrin-containing poly(4-vinylbenzyltrimethylammonium chloride) are described. Evidence for tightened multilayers has been obtained from gas permeation, swelling and quartz crystal microbalance with dissipation (QCM-D) measurements.
August 13, 2018: Chemical Communications: Chem Comm
Juan Liu, Congming Xiao
Lay-by-layer (LbL) assembly among water-soluble chitosan (WSC), sodium alginate (SA) and copper ion was applied to form polysaccharide-based flame retardant coating on polyester fabric. Thermogravimetric analysis (TGA) results indicated the thermal decomposition temperature of the surface-modified sample was higher than that of the original one, and increased with increasing the layers. Microscale combustion calorimetry (MCC) measurements exhibited that the heat release rate (HRR) values of the samples containing various layers were lower than that of unmodified sample and decreased as increasing layers...
August 9, 2018: International Journal of Biological Macromolecules
Nilesh B Karalkar, Steven A Benner
'Grand Challenges' offer ways to discover flaws in existing theory without first needing to guess what those flaws are. Our grand challenge here is to reproduce the Darwinism of terran biology, but on molecular platforms different from standard DNA. Access to Darwinism distinguishes the living from the non-living state. However, theory suggests that any biopolymer able to support Darwinism must (a) be able to form Schrödinger's `aperiodic crystal', where different molecular components pack into a single crystal lattice, and (b) have a polyelectrolyte backbone...
August 8, 2018: Current Opinion in Chemical Biology
Xiao Xu, Stefano Angioletti-Uberti, Yan Lu, Joachim Dzubiella, Matthias Ballauff
We discuss recent investigations of the interaction of polyelectrolytes with proteins. In particular, we review our recent studies on the interaction of simple proteins as human serum albumin (HSA) or lysozyme with linear polyelectrolytes, charged dendrimers, charged networks, and polyelectrolyte brushes. In all cases discussed here we combined experimental work with molecular dynamics (MD) simulations and meanfield theories. In particular, isothermal titration calorimetry (ITC) has been employed to obtain the respective binding constants Kb and the Gibbs free energy of binding...
August 10, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Hande E Cingil, Nicky C H Meertens, Ilja K Voets
Responsive materials, which can adapt and operate autonomously under dynamic conditions, are a stepping stone towards functional, life-like systems inspired by fueled self-assembly processes in nature. Complex coacervate core micelles (C3Ms) comprising oppositely charged macromolecules constitute a novel class of polymeric micelles ideally suited for use as responsive nanoscopic delivery vehicles of hydrophilic and hydrophobic cargo. To fully exploit their potential, it is important that the C3Ms form and fall apart in an autonomous fashion as orchestrated by dynamic cues in their environment...
August 10, 2018: Small
Xiaojie Lv, Wenchang Zhang, Yunen Liu, Yan Zhao, Jinsong Zhang, Mingxiao Hou
Polyelectrolyte complex (PECs) hydrogels with high hygroscopicity modulation ability were successfully prepared based on carboxymethyl chitosan (CMCS)/alginate. The swelling ratio of the hydrogels could be tuned from 1 to 450 simply by changing the weight ratio of CMCS to alginate, and superabsorbent hydrogels were obtained when the weight ratio of CMCS to alginate was below 1/1. Also, the swelling kinetics and water diffusion mechanism in the hydrogels were discussed. In vitro cytotoxicity results indicated that hydrogels had excellent cytocompatibility...
October 15, 2018: Carbohydrate Polymers
Marcia P M Costa, Letícia M Prates, Leonardo Baptista, Maurício T M Cruz, Ivana L M Ferreira
The formation of a polyelectrolyte complex through dimers of alginate and chitosan in the presence of sodium cations (SA/CS), and its interaction with the glyphosate herbicide, has been investigated at the DFT level (B3LYP/6‒311+G(d,p)). The lowest energy structure for SA/CS presents one Na+ cation coordinated to both dimers and formation of two H-bonds involving COO- and NH3 + . The coordination energy of Na+ contributes with about 40% of the total complex stabilization energy. LMOEDA method indicates important contribution of covalent nature to stabilization of SA/CS...
October 15, 2018: Carbohydrate Polymers
Leoncio Garrido, Inmaculada Aranaz, Alberto Gallardo, Carolina García, Nuria García, Esperanza Benito, Julio Guzman
The conductive and diffusional behavior of electrolytes in media with different dielectric and viscoelastic properties is investigated. A revised model to separate the contribution of dissociated and non-dissociated species to the diffusion coefficients determined with NMR is proposed. Impedance spectroscopy is used to measure the ionic conductivity of lithium salts in aqueous medium, ionic liquids in aprotic solvents and hydrogel polyelectrolytes. The diffusion coefficients of the species of interest in those systems are determined with multinuclear pulsed-gradient spin-echo (PGSE) NMR...
August 9, 2018: Journal of Physical Chemistry. B
Jong Keun Park, Jieqian Zhang, Raghunath Roy, Shouren Ge, Phillip D Hustad
Polyelectrolyte multilayer films (PEMs) are conventionally prepared by a layer-by-layer (LbL) deposition of alternating polycation and polyanion solutions. We introduce herein a block copolymer (BCP) approach employing a BCP with an H-bond acceptor block and a protected H-donor block as a masked polyampholyte to form new types of PEMs.
August 8, 2018: Chemical Communications: Chem Comm
Muge Kilicarslan, Miray Ilhan, Ozge Inal, Kaan Orhan
In this study, Clindamycin phosphate loaded adhesive polyelectrolyte complex films for local periodontal therapy were prepared with alginate and chitosan. The thickness, content uniformity, structure, swelling, adhesion and in vitro drug release with release kinetics of formulations were evaluated. The effects of the varying concentration and molecular weight of polymers used and the volume of the polymer solutions on the characteristics of the films were investigated. Increasing the concentration of sodium alginate in total content of polymer mixture caused to higher adhesiveness...
August 4, 2018: European Journal of Pharmaceutical Sciences
Maelenn Chevreuil, Didier Law-Hine, Jingzhi Chen, Stéphane Bressanelli, Sophie Combet, Doru Constantin, Jéril Degrouard, Johannes Möller, Mehdi Zeghal, Guillaume Tresset
The survival of viruses partly relies on their ability to self-assemble inside host cells. Although coarse-grained simulations have identified different pathways leading to assembled virions from their components, experimental evidence is severely lacking. Here, we use time-resolved small-angle X-ray scattering to uncover the nonequilibrium self-assembly dynamics of icosahedral viral capsids packaging their full RNA genome. We reveal the formation of amorphous complexes via an en masse pathway and their relaxation into virions via a synchronous pathway...
August 6, 2018: Nature Communications
Xin Xu, Mark Billing, Marina Ruths, Harm-Anton Klok, Jing Yu
The unique functionalities of polyelectrolyte brushes depend on several types of specific interactions, including solvent structure effects, hydrophobic forces, electrostatic interactions, and specific ion interactions. Subtle variations in the solution environment can lead to conformational and surface structural changes of the polyelectrolyte brushes, which is discussed mainly from a surface interaction perspective in this review. A brief overview is given of recent theoretical and experimental progress on the structure of polyelectrolyte brushes in various environments...
August 6, 2018: Chemistry, An Asian Journal
Sebastijan Kovacic, Nina Drasinac, Albin Pintar, Ema Žagar
This work merges the fields of highly porous polymers (PolyHIPEs) and synthetic cationic polyelectrolytes, and introduces a new approach toward the synthesis of highly porous cationic polyelectrolytes. Cationic polyelectrolytes based on (3-acrylamidopropyl)-trimethylammonium chloride (AMPTMA) were synthesized directly through the oil-in-water (O/W) high internal phase emulsions (HIPEs). The resulting polyelectrolyte-based polyHIPEs are distinguished by the highly porous morphology as well as high concentration and accessibility of the cationic N-quaternized functional groups...
August 6, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
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