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Sample records for based polyelectrolyte complexes

  1. Lyophilized Chitosan/xanthan Polyelectrolyte Complex Based Mucoadhesive Inserts for Nasal Delivery of Promethazine Hydrochloride

    OpenAIRE

    G Dehghan, Mohamed Hassan; Marzuka, Marzuka

    2014-01-01

    The objective of this investigation was the development of chitosan/xanthan polyelectrolyte complex based mucoadhesive nasal insert of promethazine hydrochloride a drug used in the treatment of motion sickness. A 32 factorial design was applied for preparing chitosan/xanthan polyelectrolyte complex and to study the effect of independent variables i.e. concentration of xanthan [X1] and concentration of chitosan [X2] on various responses i.e. viscosity of polyelectrolyte complex solution, water...

  2. Design of Chitosan and Its Water Soluble Derivatives-Based Drug Carriers with Polyelectrolyte Complexes

    Directory of Open Access Journals (Sweden)

    Qing-Xi Wu

    2014-12-01

    Full Text Available Chitosan, the cationic polysaccharide derived from the natural polysaccharide chitin, has been studied as a biomaterial for more than two decades. As a polycationic polymer with favorable properties, it has been widely used to form polyelectrolyte complexes with polyanions for various applications in drug delivery fields. In recent years, a growing number of studies have been focused on the preparation of polyelectrolyte complexes based on chitosan and its water soluble derivatives. They have been considered well-suited as biomaterials for a number of vital drug carriers with targeted/controlled release profiles, e.g., films, capsules, microcapsules. In this work, an overview highlights not only the favorable properties of chitosan and its water soluble derivatives but also the good performance of the polyelectrolyte complexes produced based on chitosan. Their various types of applications as drug carriers are reviewed in detail.

  3. Chitosan Based Polyelectrolyte Complexes as Potential Carrier Materials in Drug Delivery Systems

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    Josias H. Hamman

    2010-04-01

    Full Text Available Chitosan has been the subject of interest for its use as a polymeric drug carrier material in dosage form design due to its appealing properties such as biocompatibility, biodegradability, low toxicity and relatively low production cost from abundant natural sources. However, one drawback of using this natural polysaccharide in modified release dosage forms for oral administration is its fast dissolution rate in the stomach. Since chitosan is positively charged at low pH values (below its pKa value, it spontaneously associates with negatively charged polyions in solution to form polyelectrolyte complexes. These chitosan based polyelectrolyte complexes exhibit favourable physicochemical properties with preservation of chitosan’s biocompatible characteristics. These complexes are therefore good candidate excipient materials for the design of different types of dosage forms. It is the aim of this review to describe complexation of chitosan with selected natural and synthetic polyanions and to indicate some of the factors that influence the formation and stability of these polyelectrolyte complexes. Furthermore, recent investigations into the use of these complexes as excipients in drug delivery systems such as nano- and microparticles, beads, fibers, sponges and matrix type tablets are briefly described.

  4. Microparticles based on chitosan/carboxymethylcellulose polyelectrolyte complexes for colon delivery of vancomycin.

    Science.gov (United States)

    Cerchiara, T; Abruzzo, A; Parolin, C; Vitali, B; Bigucci, F; Gallucci, M C; Nicoletta, F P; Luppi, B

    2016-06-01

    The aim of this work was to prepare polyelectrolyte complexes based on chitosan (CH) and carboxymethylcellulose (CMC) for colon delivery of vancomycin (VM). Various batches of polyelectrolyte complexes, using three different CH/CMC weight ratios (3:1, 1:1 and 1:3), were prepared and collected as microparticles by spray-drying process. Microparticles were characterized in terms of yield, encapsulation efficiency, drug loading, morphology and mucoadhesion properties. Microparticles water-uptake and VM release as well as its protection against gastric pepsin degradation were also investigated. Finally, the antibacterial activity against Staphylococcus aureus, a Gram-positive model strain, was evaluated. The best formulation CH/CMC 1:3 was selected based on the encapsulation efficiency, water-uptake and drug release rate. Moreover, microparticles were able to prevent VM degradation and showed a good antibacterial activity against S. aureus. Finally, to improve the release of VM in the colon the selected formulation was coated with lauric acid. PMID:27083351

  5. Characterization for Soil Fixation by Polyelectrolyte Complex

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong Suk; Kwon, Sang Woon; Yang, Heeman; Lee, Kune Woo; Seo, Bumkyoung; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    According to report, the radioactivity bulk (approx. 95%) is localized within topsoil. Therefore soil surface on topsoil should be fixed to prevent the spreading of the contaminated soils with Cs-137 by wind and water erosion. Many methods have been developing for soil fixation to remove radioactive contaminants in soil and prevent to diffuse radioactive materials. Various materials have been also used as fixatives such as clays, molecular sieves, polymer, and petroleum based products. One of the methods is a soil fixation or solidification using polyelectrolyte. Polyelectrolytes have many ionic groups and make into the polyelectrolyte complex (PEC) due to electrostatic interaction of polyanion and polycation in an aqueous solution. It can be avoids using the chemical cross-linking agents, and reducing the possible toxicity and other undesirable effects of the reagents. PEC can fix soil particles by flocculation and formation of crust between soil. The method can also prevent a spread of radioactive material by floating on a soil surface. Recently, PEC used for the solidification of soil near the Fukushima nuclear power plant in Japan. The decontamination efficiency of the surface soils reached 90%, and dust release was effectively suppressed during the removal of surface soils. In this study, it was investigated the fixation of the soil by PEC to avoid the spread of the contamination in addition to the separation of soil and PEC. The physicochemical properties of polyelectrolyte complex solution and the stability of fixed soil by PEC were investigated. The mode of the addition is important to prepare the polyelectrolytes complex without PAA agglomerate. The concentration of salt in the polyelectrolyte complex solution is a very important parameter for the soil fixation.

  6. Synthesis and characterization of chitosan-based polyelectrolyte complexes, doped by quantum dots

    Science.gov (United States)

    Abuzova, N. V.; Gerasimova, M. A.; Slabko, V. V.; Slyusareva, E. A.

    2015-12-01

    Doping of polymer particles by a fluorophores results in the sensitization within the visible spectral region becoming very promising materials for sensor applications. Colloids of biocompatible chitosan-based polyelectrolyte complexes (PECs) doped with quantum dots (QD) of CdTe and CdSe/ZnS (with sizes of 2.0-2.4 nm) were synthesized and characterized by scanning electron microscopy, dynamic light scattering, ζ-potential measurements, absorption and luminescence (including time-resolved) spectroscopy. The influence of ionic strength (0.02-1.5 M) on absorption and photoluminescence properties of encapsulated into PEC and unencapsulated quantum dots was investigated. The stability of the emission intensity of the encapsulated quantum dots has been shown to be strongly dependent on concentration of quantum dots.

  7. FORMULATION AND EVALUATION OF MATRIX TABLETS BASED ON POLYELECTROLYTE COMPLEX BETWEEN OKRA MUCILAGE AND CHITOSAN

    Directory of Open Access Journals (Sweden)

    Ashwini Rajendra

    2012-02-01

    Full Text Available Recent years there has been greater utilization of natural polymers in the development of delivery systems. The present work is an effort towards development of matrix tablets using polyelectrolyte complex formed between the oppositely charged natural polymers like okra mucilage obtained from pods of Abelmoschus esculentus and chitosan. The effect of pH and polymer volume ratio on yield of polyelectrolyte complex was studied. It was observed that the yield was maximum (96.45% at pH 5 and at polymer volume ratio of 9:1 between okra mucilage and chitosan. The prepared polyelectrolyte complex was also characterised by conductimetry, FTIR, DSC. The results confirmed the formation of polyelectrolyte complex between the natural polymers. The matrix tablets were formulated for model drug diclofenac sodium using the best polyelectrolyte complex at different drug to polymer ratios and compared with formulations containing individual polymers as well as marketed formulation. The prepared formulations showed satisfactory physical parameters. Formulations F2 and F3 extended the drug release for more than 8 h with (83.87± 0.8321% and (77.125± 0.125% drug release respectively in 8 h. The formulations F2 and F3 followed zero order kinetics with anomalous diffusion mechanism. The mean dissolution times were 3.6042 and 3.5935 hrs and the % dissolution efficiency were 54.9467 and 55.7203 % for formulations F2 and F3 respectively. The similarity factor f2 for formulation F2 was 61.6751 and for formulation F3, it was found to be 60.5025.The formulations were found to be stable.

  8. Polyelectrolyte complex micelles by self-assembly of polypeptide-based triblock copolymer for doxorubicin delivery

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    Jeong Hwan Kim

    2014-08-01

    Full Text Available Polyelectrolyte complex micelles were prepared by self-assembly of polypeptide-based triblock copolymer as a new drug carrier for cancer chemotherapy. The triblock copolymer, poly(l-aspartic acid-b-poly(ethylene glycol-b-poly(l-aspartic acid (PLD-b-PEG-b-PLD, spontaneously self-assembled with doxorubicin (DOX via electrostatic interactions to form spherical micelles with a particle size of 60–80 nm (triblock ionomer complexes micelles, TBIC micelles. These micelles exhibited a high loading capacity of 70% (w/w at a drug/polymer ratio of 0.5 at pH 7.0. They showed pH-responsive release patterns, with higher release at acidic pH than at physiological pH. Furthermore, DOX-loaded TBIC micelles exerted less cytotoxicity than free DOX in the A-549 human lung cancer cell line. Confocal microscopy in A-549 cells indicated that DOX-loaded TBIC micelles were transported into lysosomes via endocytosis. These micelles possessed favorable pharmacokinetic characteristics and showed sustained DOX release in rats. Overall, these findings indicate that PLD-b-PEG-b-PLD polypeptide micelles are a promising approach for anti-cancer drug delivery.

  9. Evaluation of polyelectrolyte complex-based scaffolds for mesenchymal stem cell therapy in cardiac ischemia treatment.

    Science.gov (United States)

    Ceccaldi, Caroline; Bushkalova, Raya; Alfarano, Chiara; Lairez, Olivier; Calise, Denis; Bourin, Philippe; Frugier, Celine; Rouzaud-Laborde, Charlotte; Cussac, Daniel; Parini, Angelo; Sallerin, Brigitte; Fullana, Sophie Girod

    2014-02-01

    Three-dimensional (3D) scaffolds hold great potential for stem cell-based therapies. Indeed, recent results have shown that biomimetic scaffolds may enhance cell survival and promote an increase in the concentration of therapeutic cells at the injury site. The aim of this work was to engineer an original polymeric scaffold based on the respective beneficial effects of alginate and chitosan. Formulations were made from various alginate/chitosan ratios to form opposite-charge polyelectrolyte complexes (PECs). After freeze-drying, the resultant matrices presented a highly interconnected porous microstructure and mechanical properties suitable for cell culture. In vitro evaluation demonstrated their compatibility with mesenchymal stell cell (MSC) proliferation and their ability to maintain paracrine activity. Finally, the in vivo performance of seeded 3D PEC scaffolds with a polymeric ratio of 40/60 was evaluated after an acute myocardial infarction provoked in a rat model. Evaluation of cardiac function showed a significant increase in the ejection fraction, improved neovascularization, attenuated fibrosis as well as less left ventricular dilatation as compared to an animal control group. These results provide evidence that 3D PEC scaffolds prepared from alginate and chitosan offer an efficient environment for 3D culturing of MSCs and represent an innovative solution for tissue engineering.

  10. Highly sensitive and fast responsive fiber-optic modal interferometric pH sensor based on polyelectrolyte complex and polyelectrolyte self-assembled nanocoating.

    Science.gov (United States)

    Yin, Mingjie; Gu, Bobo; Zhao, Qiang; Qian, Jinwen; Zhang, Aping; An, Quanfu; He, Sailing

    2011-04-01

    A new fiber-optic pH sensor is demonstrated by coating negatively charged polyelectrolyte complex (PEC(-)) nanoparticles, made of sodium carboxymethyl cellulose and poly(diallyldimethylammonium chloride) (PDDA), and positively charged PDDA on the surface of a thin-core fiber modal interferometer (TCFMI) with a layer-by-layer (LbL) electrostatic self-assembly method. The fabricated TCFMI pH sensor has different transmission dip wavelengths under different pH values and shows high sensitivities of 0.6 nm/pH unit and -0.85 nm/pH unit for acidic and alkaline solutions, respectively, and short response time of 30-50 s. The LbL electrostatic self-assembly process of a PEC(-)/PDDA multilayer is traced by quartz crystal microbalance and shows a fast thickness growth. Atomic force microscopy shows the root mean square (RMS) surface roughness of electrostatic self-assembly nanocoating of polyelectrolyte complex/polyelectrolyte is much higher than that of polyelectrolyte/polyelectrolyte due to the larger size of PEC(-) colloidal nanoparticles. The enhanced RMS surface roughness and thickness of the nanocoating can shorten the response time and raise the sensitivity of the TCFMI pH sensor, respectively. In addition, the TCFMI pH sensor has highly reversible performance and good durability. PMID:21318252

  11. Stereoregularity Drives Precipitation in Polyelectrolyte Complex Formation

    Science.gov (United States)

    Tirrell, Matthew; Perry, Sarah; Leon, Lorraine; Kade, Matthew; Priftis, Dimitris; Black, Katie; Hoffman, Kyle; Whitmer, Jonathan; Qin, Jian; de Pablo, Juan

    2014-03-01

    This study investigates the effect of stereoregularity on the formation of polypeptide-based complex formation and assembly into micelles, hydrogels and ordered phases. We demonstrate that fluid complex coacervate formation (rather than solid complex precipitation) between oppositely charged polypeptides requires at least one racemic partner in order to disrupt backbone hydrogen bonding networks and prevent the hydrophobic collapse of the polymers into compact, fibrillar secondary structures. Computer simulations bear this out and enable visualization of the molecular structure of the complexes. The ability to choose between conditions of fluid phase formation and solid phase formation is a useful tool in developing new self-assembled materials based on polyelectrolyte complex formation. Support from the Argonne National Laboratory Laboratory Research and Development Program (2011-217) is gratefully acknowledged.

  12. Influence of the Hydrophobicity of Polyelectrolytes on Polyelectrolyte Complex Formation and Complex Particle Structure and Shape

    OpenAIRE

    Gudrun Petzold; Andreas Janke; Stefan Zschoche; Simona Schwarz; Mandy Mende

    2011-01-01

    Polyelectrolyte complexes (PECs) were prepared by structural uniform and strongly charged cationic and anionic modified alternating maleic anhydride copolymers. The hydrophobicity of the polyelectrolytes was changed by the comonomers (ethylene, isobutylene and styrene). Additionally, the n−/n+ ratio of the molar charges of the polyelectrolytes and the procedure of formation were varied. The colloidal stability of the systems and the size, shape, and structure of the PEC particles were investi...

  13. Complexation of two oppositely charged polyelectrolytes

    Science.gov (United States)

    Shojaei, Hamidreza; Muthukumar, Murugappan

    Existence of both polycation and polyanion in a solution will lead to complexation. We investigate both dynamics and the steady state solution for complexation of two oppositely charged polyelectrolytes in a salty solution. By use of Smoluchowski equation, both dynamic and steady-state properties of a complexation event occurring were studied.

  14. Nasal inserts containing ondansetron hydrochloride based on Chitosan-gellan gum polyelectrolyte complex: In vitro-in vivo studies.

    Science.gov (United States)

    Sonje, Ashish G; Mahajan, Hitendra S

    2016-07-01

    The aim of this study was the production of ondansetron hydrochloride loaded lyophilized insert for nasal delivery. The nasal insert was prepared by the lyophilisation technique using Chitosan-gellan gum polyelectrolyte complex as the polymer matrix. The ondansetron loaded inserts were evaluated with respect to water uptake, bioadhesion, drug release kinetic study, ex vivo permeation study, and in vivo study. Lyophilised nasal inserts were characterized by differential scanning calorimetry, scanning electron microscopy and X-ray diffraction study. Scanning electron microscopy confirmed the porous sponge like structure of inserts whereas release kinetic model revealed that drug release followed non-fickian case II diffusion. The nasal delivery showed improved bioavailability as compared to oral delivery. In conclusion, the ondansetron containing nasal inserts based on Chitosan-gellan gum complex with potential muco-adhesive potential is suitable for nasal delivery. PMID:27127060

  15. Cationic drug-based self-assembled polyelectrolyte complex micelles: Physicochemical, pharmacokinetic, and anticancer activity analysis.

    Science.gov (United States)

    Ramasamy, Thiruganesh; Poudel, Bijay Kumar; Ruttala, Himabindu; Choi, Ju Yeon; Hieu, Truong Duy; Umadevi, Kandasamy; Youn, Yu Seok; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

    2016-10-01

    Nanofabrication of polymeric micelles through self-assembly of an ionic block copolymer and oppositely charged small molecules has recently emerged as a promising method of formulating delivery systems. The present study therefore aimed to investigate the interaction of cationic drugs doxorubicin (DOX) and mitoxantrone (MTX) with the anionic block polymer poly(ethylene oxide)-block-poly(acrylic acid) (PEO-b-PAA) and to study the influence of these interactions on the pharmacokinetic stability and antitumor potential of the formulated micelles in clinically relevant animal models. To this end, individual DOX and MTX-loaded polyelectrolyte complex micelles (PCM) were prepared, and their physicochemical properties and pH-responsive release profiles were studied. MTX-PCM and DOX-PCM exhibited a different release profile under all pH conditions tested. MTX-PCM exhibited a monophasic release profile with no initial burst, while DOX-PCM exhibited a biphasic release. DOX-PCM showed a higher cellular uptake than that shown by MTX-PCM in A-549 cancer cells. Furthermore, DOX-PCM induced higher apoptosis of cancer cells than that induced by MTX-PCM. Importantly, both MTX-PCM and DOX-PCM showed prolonged blood circulation. MTX-PCM improved the AUCall of MTX 4-fold compared to a 3-fold increase by DOX-PCM for DOX. While a definite difference in blood circulation was observed between MTX-PCM and DOX-PCM in the pharmacokinetic study, both MTX-PCM and DOX-PCM suppressed tumor growth to the same level as the respective free drugs, indicating the potential of PEGylated polymeric micelles as effective delivery systems. Taken together, our results show that the nature of interactions of cationic drugs with the polyionic copolymer can have a tremendous influence on the biological performance of a delivery system. PMID:27318960

  16. Structures of some surfactant–polyelectrolyte complexes

    Indian Academy of Sciences (India)

    Rema Krishnaswamy; V A Raghunathan; A K Sood

    2003-08-01

    Structures of complexes formed in aqueous solutions by some anionic polyelectrolytes (double and single stranded (ds and ss) DNA, poly(vinyl sulfonate) (PVS), and poly(styrene sulfonate) (PSS)) with a cationic surfactant system consisting of cetyltrimethylammonium bromide (CTAB) and sodium 3-hydroxy-2-naphthoate (SHN) have been determined using small angle X-ray diffraction. All complexes are found to have a two-dimensional (2-D) hexagonal structure at low SHN concentrations. Analysis of the diffraction data shows that the ds DNA–CTAB complex has an intercalated structure, with each DNA strand surrounded by three cylindrical micelles. On increasing SHN concentration, DNA–CTAB–SHN complexes exhibit a hexagonal-to-lamellar transition, whereas PVS complexes show a hexagonal → centered rectangular → lamellar transition. PSS complexes show yet another sequence of structures. These results indicate the significant influence of the chemical nature of the polyelectrolyte on the structure of the complexes.

  17. Polyelectrolyte Complex Based Interfacial Drug Delivery System with Controlled Loading and Improved Release Performance for Bone Therapeutics

    Directory of Open Access Journals (Sweden)

    David Vehlow

    2016-03-01

    Full Text Available An improved interfacial drug delivery system (DDS based on polyelectrolyte complex (PEC coatings with controlled drug loading and improved release performance was elaborated. The cationic homopolypeptide poly(l-lysine (PLL was complexed with a mixture of two cellulose sulfates (CS of low and high degree of substitution, so that the CS and PLL solution have around equal molar charged units. As drugs the antibiotic rifampicin (RIF and the bisphosphonate risedronate (RIS were integrated. As an important advantage over previous PEC systems this one can be centrifuged, the supernatant discarded, the dense pellet phase (coacervate separated, and again redispersed in fresh water phase. This behavior has three benefits: (i Access to the loading capacity of the drug, since the concentration of the free drug can be measured by spectroscopy; (ii lower initial burst and higher residual amount of drug due to removal of unbound drug and (iii complete adhesive stability due to the removal of polyelectrolytes (PEL excess component. It was found that the pH value and ionic strength strongly affected drug content and release of RIS and RIF. At the clinically relevant implant material (Ti40Nb similar PEC adhesive and drug release properties compared to the model substrate were found. Unloaded PEC coatings at Ti40Nb showed a similar number and morphology of above cultivated human mesenchymal stem cells (hMSC compared to uncoated Ti40Nb and resulted in considerable production of bone mineral. RIS loaded PEC coatings showed similar effects after 24 h but resulted in reduced number and unhealthy appearance of hMSC after 48 h due to cell toxicity of RIS.

  18. Investigation of metal-polyelectrolyte complex toxicity.

    Science.gov (United States)

    Karahan, Mesut; Mustafaeva, Zeynep; Koç, Rabia Çakır; Bağırova, Melahat; Allahverdiyev, Adil M

    2014-05-01

    Water-soluble binary and ternary copper complexes of polyelectrolytes were synthesized, and the toxicity of these complexes was tested in mouse fibroblast cell line (L929) in vitro. Both the binary and ternary complexes were prepared at the ratio of 0.4 mole copper(II) ions per monomer of acrylic acid and 0.5 mole copper(II) ions per monomer of methyl vinyl ether maleic anhydride, furthermore at the ratio of 1 and 2 mole bovine serum albumin per mole of polyacrylic acid and poly(methyl vinyl ether-co-maleic anhydride), respectively. Compared to binary copper(II)-polyelectrolyte complexes, these ternary complexes have been determined to be of least toxicity. PMID:22914259

  19. A drug-loaded gel based on polyelectrolyte complexes of poly (acrylic acid) with poly (vinylpyrrolidone) and chitosan

    International Nuclear Information System (INIS)

    A drug-loaded gel (CSPP) based on ionic crosslinked chitosan (CS) and polyelectrolyte complexes of poly (acrylic acid) (PAA) with poly (vinylpyrrolidone) (PVP) was prepared by dropping CS solution containing suitable amount of PVP into PAA and trisodium citrate co-existing gelling solution. The surface and cross-section morphology of the gel was observed using scanning electron microscopy, and the observation showed that the CSPP gel had more compact structure than CS gel. In vitro release profiles of model drug from the CSPP gel, which was prepared under different conditions, were investigated in simulative gastric fluid (pH 1.8) using an UV/vis spectrophotometer. The results showed that the rapid release of the model was restrained due to the complex of PVP and PAA, and the CSPP gel could serve as a suitable candidate in drug delivery system such as the site-specific controlled release of the drug in stomach. In addition, the release mechanism of drug was analyzed by fitting the amount of drug released into Peppa's potential equation.

  20. Synthesis of nanosilver loaded chitosan/poly(acrylamide-co-itaconic acid) based inter-polyelectrolyte complex films for antimicrobial applications.

    Science.gov (United States)

    Bajpai, S K; Jyotishi, Pooja; Bajpai, M

    2016-12-10

    In the present work, AgNPs loaded chitosan/poly(acrylamide-co-itaconic acid) inter-polyelectrolyte complex (IPC) films have been prepared for antimicrobial applications. The AgNPs-loaded IPC films have been characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and Surface plasmon resonance (SPR). Particle size of synthesized AgNPs was found to be in the range 10-30nm. These films exhibited a remarkable antibacterial property against strong pathogen E.Coli, thus offering their candidature for antimicrobial applications. PMID:27577913

  1. Theoretical investigation of ordering and complexation in solutions of polyelectrolytes

    OpenAIRE

    Oskolkov, Nikolay

    2007-01-01

    The PhD thesis is dedicated to the theoretical investigation of two effects taking place in the ion-containing polymeric systems, namely, nematic ordering in solutions of rodlike polyelectrolytes and complexation in solutions of oppositely charged polyelectrolytes taking into account the effect of charge inversion (overcharging) of macroions. The correlation free energy of electrostatic interactions in solutions of rodlike polyelectrolytes was calculated within the framework of the Debye-H...

  2. Influence of the Hydrophobicity of Polyelectrolytes on Polyelectrolyte Complex Formation and Complex Particle Structure and Shape

    Directory of Open Access Journals (Sweden)

    Gudrun Petzold

    2011-08-01

    Full Text Available Polyelectrolyte complexes (PECs were prepared by structural uniform and strongly charged cationic and anionic modified alternating maleic anhydride copolymers. The hydrophobicity of the polyelectrolytes was changed by the comonomers (ethylene, isobutylene and styrene. Additionally, the n−/n+ ratio of the molar charges of the polyelectrolytes and the procedure of formation were varied. The colloidal stability of the systems and the size, shape, and structure of the PEC particles were investigated by turbidimetry, dynamic light scattering (DLS and atomic force microscopy (AFM. Dynamic light scattering indicates that beside large PEC particle aggregates distinct smaller particles were formed by the copolymers which have the highest hydrophobicity (styrene. These findings could be proved by AFM. Fractal dimension (D, root mean square (RMS roughness and the surface profiles of the PEC particles adsorbed on mica allow the following conclusions: the higher the hydrophobicity of the polyelectrolytes, the broader is the particle size distribution and the minor is the swelling of the PEC particles. Hence, the most compact particles are formed with the very hydrophobic copolymer.

  3. Modeling competitive substitution in a polyelectrolyte complex

    Science.gov (United States)

    Peng, B.; Muthukumar, M.

    2015-12-01

    We have simulated the invasion of a polyelectrolyte complex made of a polycation chain and a polyanion chain, by another longer polyanion chain, using the coarse-grained united atom model for the chains and the Langevin dynamics methodology. Our simulations reveal many intricate details of the substitution reaction in terms of conformational changes of the chains and competition between the invading chain and the chain being displaced for the common complementary chain. We show that the invading chain is required to be sufficiently longer than the chain being displaced for effecting the substitution. Yet, having the invading chain to be longer than a certain threshold value does not reduce the substitution time much further. While most of the simulations were carried out in salt-free conditions, we show that presence of salt facilitates the substitution reaction and reduces the substitution time. Analysis of our data shows that the dominant driving force for the substitution process involving polyelectrolytes lies in the release of counterions during the substitution.

  4. Modeling competitive substitution in a polyelectrolyte complex

    Energy Technology Data Exchange (ETDEWEB)

    Peng, B.; Muthukumar, M., E-mail: muthu@polysci.umass.edu [Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003 (United States)

    2015-12-28

    We have simulated the invasion of a polyelectrolyte complex made of a polycation chain and a polyanion chain, by another longer polyanion chain, using the coarse-grained united atom model for the chains and the Langevin dynamics methodology. Our simulations reveal many intricate details of the substitution reaction in terms of conformational changes of the chains and competition between the invading chain and the chain being displaced for the common complementary chain. We show that the invading chain is required to be sufficiently longer than the chain being displaced for effecting the substitution. Yet, having the invading chain to be longer than a certain threshold value does not reduce the substitution time much further. While most of the simulations were carried out in salt-free conditions, we show that presence of salt facilitates the substitution reaction and reduces the substitution time. Analysis of our data shows that the dominant driving force for the substitution process involving polyelectrolytes lies in the release of counterions during the substitution.

  5. Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations.

    Science.gov (United States)

    Ou, Zhaoyang; Muthukumar, M

    2006-04-21

    We report a systematic study by Langevin dynamics simulation on the energetics of complexation between two oppositely charged polyelectrolytes of same charge density in dilute solutions of a good solvent with counterions and salt ions explicitly included. The enthalpy of polyelectrolyte complexation is quantified by comparisons of the Coulomb energy before and after complexation. The entropy of polyelectrolyte complexation is determined directly from simulations and compared with that from a mean-field lattice model explicitly accounting for counterion adsorption. At weak Coulomb interaction strengths, e.g., in solvents of high dielectric constant or with weakly charged polyelectrolytes, complexation is driven by a negative enthalpy due to electrostatic attraction between two oppositely charged chains, with counterion release entropy playing only a subsidiary role. In the strong interaction regime, complexation is driven by a large counterion release entropy and opposed by a positive enthalpy change. The addition of salt reduces the enthalpy of polyelectrolyte complexation by screening electrostatic interaction at all Coulomb interaction strengths. The counterion release entropy also decreases in the presence of salt, but the reduction only becomes significant at higher Coulomb interaction strengths. More significantly, in the range of Coulomb interaction strengths appropriate for highly charged polymers in aqueous solutions, complexation enthalpy depends weakly on salt concentration and counterion release entropy exhibits a large variation as a function of salt concentration. Our study quantitatively establishes that polyelectrolyte complexation in highly charged Coulomb systems is of entropic origin.

  6. Structural study of coacervation in protein-polyelectrolyte complexes

    Science.gov (United States)

    Chodankar, S.; Aswal, V. K.; Kohlbrecher, J.; Vavrin, R.; Wagh, A. G.

    2008-09-01

    Coacervation is a dense liquid-liquid phase separation and herein we report coacervation of protein bovine serum albumin (BSA) in the presence of polyelectrolyte sodium polystyrene sulfonate (NaPSS) under varying solution conditions. Small-angle neutron scattering (SANS) measurements have been performed on above protein-polyelectrolyte complexes to study the structural evolution of the process that leads to coacervation and the phase separated coacervate as a function of solution pH , protein-polyelectrolyte ratio and ionic strength. SANS study prior to phase separation on the BSA-NaPSS complex shows a fractal structure representing a necklace model of protein macromolecules randomly distributed along the polystyrene sulfonate chain. The fractal dimension of the complex decreases as pH is shifted away from the isoelectric point (˜4.7) of BSA protein, which indicates the decrease in the compactness of the complex structure due to increase in the charge repulsion between the protein macromolecules bound to the polyelectrolyte. Concentration-dependence studies of the polyelectrolyte in the complex suggest coexistence of two populations of polyelectrolytes, first one fully saturated with proteins and another one free from proteins. Coacervation phase has been obtained through the turbidity measurement by varying pH of the aqueous solution containing protein and polyelectrolyte from neutral to acidic regime to get them to where the two components are oppositely charged. The spontaneous formation of coacervates is observed for pH values less than 4. SANS study on coacervates shows two length scales related to complex aggregations (mesh size and overall extent of the complex) hierarchically branched to form a larger network. The mesh size represents the distance between cross-linked points in the primary complex, which decreases with increase in ionic strength and remains the same on varying the protein-polyelectrolyte ratio. On the other hand, the overall extent of the

  7. Complex coacervation of supercharged proteins with polyelectrolytes.

    Science.gov (United States)

    Obermeyer, Allie C; Mills, Carolyn E; Dong, Xue-Hui; Flores, Romeo J; Olsen, Bradley D

    2016-04-21

    Complexation of proteins with polyelectrolytes or block copolymers can lead to phase separation to generate a coacervate phase or self-assembly of coacervate core micelles. However, many proteins do not coacervate at conditions near neutral pH and physiological ionic strength. Here, protein supercharging is used to systematically explore the effect of protein charge on the complex coacervation with polycations. Four model proteins were anionically supercharged to varying degrees as quantified by mass spectrometry. Proteins phase separated with strong polycations when the ratio of negatively charged residues to positively charged residues on the protein (α) was greater than 1.1-1.2. Efficient partitioning of the protein into the coacervate phase required larger α (1.5-2.0). The preferred charge ratio for coacervation was shifted away from charge symmetry for three of the four model proteins and indicated an excess of positive charge in the coacervate phase. The composition of protein and polymer in the coacervate phase was determined using fluorescently labeled components, revealing that several of the coacervates likely have both induced charging and a macromolecular charge imbalance. The model proteins were also encapsulated in complex coacervate core micelles and micelles formed when the protein charge ratio α was greater than 1.3-1.4. Small angle neutron scattering and transmission electron microscopy showed that the micelles were spherical. The stability of the coacervate phase in both the bulk and micelles improved to increased ionic strength as the net charge on the protein increased. The micelles were also stable to dehydration and elevated temperatures.

  8. Employment of Gibbs-Donnan-based concepts for interpretation of the properties of linear polyelectrolyte solutions

    Science.gov (United States)

    Marinsky, J.A.; Reddy, M.M.

    1991-01-01

    Earlier research has shown that the acid dissociation and metal ion complexation equilibria of linear, weak-acid polyelectrolytes and their cross-linked gel analogues are similarly sensitive to the counterion concentration levels of their solutions. Gibbs-Donnan-based concepts, applicable to the gel, are equally applicable to the linear polyelectrolyte for the accommodation of this sensitivity to ionic strength. This result is presumed to indicate that the linear polyelectrolyte in solution develops counterion-concentrating regions that closely resemble the gel phase of their analogues. Advantage has been taken of this description of linear polyelectrolytes to estimate the solvent uptake by these regions. ?? 1991 American Chemical Society.

  9. Novel porous scaffolds of pH responsive chitosan/carrageenan-based polyelectrolyte complexes for tissue engineering.

    Science.gov (United States)

    Araujo, J V; Davidenko, N; Danner, M; Cameron, R E; Best, S M

    2014-12-01

    Polyelectrolyte complexes (PECs) represent promising materials for drug delivery and tissue engineering applications. These substances are obtained in aqueous medium without the need for crosslinking agents. PECs can be produced through the combination of oppositely charged medical grade polymers, which include the stimuli responsive ones. In this work, three-dimensional porous scaffolds were produced through the lyophilization of pH sensitive PECs made of chitosan (CS) and carrageenan (CRG). CS:CRG molar ratios of 1:1 (CSCRG1), 2:1 (CSCRG2), and 3:1 (CSCRG3) were used. The chemical compositions of the PECs, as well as their influence in the final structure of the scaffolds were meticulously studied. In addition, the pH responsiveness of the PECs in a range including the physiological pH values of 7.4 (simulating normal physiological conditions) and 4.5 (simulating inflammatory response) was assessed. Results showed that the PECs produced were stable at pH values of 7.4 and under but dissolved as the pH increased to nonphysiological values of 9 and 11. However, after dissolution, the PEC could be reprecipitated by decreasing the pH to values close to 4.5. The scaffolds obtained presented large and interconnected pores, being equally sensitive to changes in the pH. CSCRG1 scaffolds appeared to have higher hydrophilicity and therefore higher water absorption capacity. The increase in the CS:CRG molar ratios improved the scaffold mechanical properties, with CSCRG3 presenting the higher compressive modulus under wet conditions. Overall, the PEC scaffolds appear promising for tissue engineering related applications that require the use of pH responsive materials stable at physiological conditions.

  10. Phase Transitions in Nanostructured Polyelectrolyte-Surfactant Complexes

    Science.gov (United States)

    Leonard, Michael; Strey, Helmut

    2001-03-01

    When a water-soluble polyelectrolyte is combined with an oppositely-charged surfactant solution at a stoichiometric charge ratio, self-assembly into highly-ordered, water-insoluble structures occurs. We have prepared such complexes with poly(sodium acrylate)-co-acrylamide, alginic acid, and chitosan, combined with cationic and anionic surfactants. The phases exhibited by these complexes in aqueous solution are highly sensitive to such factors as osmotic pressure, salt type, ionic strength, and polyelectrolyte charge density. In this study, we have used small angle X-ray scattering to examine osmotic stress-induced structural phase transitions in these complexes under these various environmental conditions. The morphological consequences of combining polyelectrolytes with swollen, emulsion-bound surfactant micelles were also investigated. Results of this work, as well as the potential to use these complexes as nanoporous, biocompatible materials, will be discussed.

  11. A molecular simulation study on salt response of polyelectrolyte complexes

    Science.gov (United States)

    Antila, Hanne; van Tassel, Paul; Sammalkorpi, Maria

    2015-03-01

    In aqueous solutions, oppositely charged polymers, polyelectrolytes (PEs) form complexes which are known to be sensitive to added salt with responses ranging from shrinking to full destabilization of the complex. As a specific application of PE complexes, the complex formation of DNA with polycations has been demonstrated to be an effective means of transfecting genetic material in gene therapy. We use all-atom molecular dynamics and coarse-grained Monte Carlo simulations to investigate the effect of excess salt on DNA-polycation complex stability. The detailed all-atom simulations demonstrate the mechanism of polycation and ion species specific salt-driven dissociation involving charge reversal. More generally, other possible mechanisms of salt driven dissociation exist as well. The coarse grained approach, which describes the PE complex as oppositely charged, rigid rods and ions as hard spheres, provides a more complete understanding of PE interactions in salt, and suggests possible mechanisms leading to repulsion between the oppositely charged polyelectrolytes.

  12. Water's Role in the Relaxation of Polyelectrolyte Complexes and Multilayers

    Science.gov (United States)

    Lutkenhaus, Jodie; Zhang, Yanpu; Reid, Dariya; Antila, Hanne; Yildirim, Erol; Zhang, Ran; Sammalkorpi, Maria

    In the last decade, evidence for an intriguing glass-transition-like phase transition has emerged in hydrated polyelectrolyte complex precipitates and polyelectrolyte multilayers. Although the transition is weak, it stimulates large-scale macroscopic phenomena such as multilayer shrinking, swelling, and rearrangement. To date, there is not a clear consensus on what causes this transition, although a growing body of evidence indicates that salt and water are key parameters. Recent simulations of hydrated polyelectrolyte complexes show that water molecules form a stabilizing hydrogen-bonded network and that this network is disrupted by dehydration of the polyanion at the thermal transition, leading to segmental relaxation of polymer chains. If true, this would explain the transition's dependence on water and extrinsic compensation as well as its glass transition-like character. This talk will focus upon water's role in the transition, in which a strong dependence on hydration is observed. Quartz crystal microbalance with dissipation (QCM-D) and modulated differential scanning calorimetry (MDSC) are used to track the transition in polyelectrolytes complexes as a function of hydration.

  13. Complex Coacervation composed of Polyelectrolytes Alginate and Chitosan

    Institute of Scientific and Technical Information of China (English)

    盛楠楠

    2016-01-01

    Alginate sodium (ALG) and chitosan (CHI) can form fiber, films, microspheres, hydrogels and all with a wide range of biomedical applications.Few works have been done as a result of the easily flocculation of chitosan in negatively charged matrix.Complex coacervation composed of polyelectrolytes alginate and chitosan were successfully fabricated.The results showed that the lower molecular weights of the chitosan is better for the fabricated of the complex coacervation.

  14. Mesenchymal stem cell recruitment by stromal derived factor-1-delivery systems based on chitosan/poly(γ-glutamic acid polyelectrolyte complexes

    Directory of Open Access Journals (Sweden)

    RM Gonçalves

    2012-04-01

    Full Text Available Human mesenchymal stem cells (hMSCs have an enormous potential for tissue engineering and cell-based therapies. With a potential of differentiation into multiple lineages and immune-suppression, these cells play a key role in tissue remodelling and regeneration.Here a method of hMSC recruitment is described, based on the incorporation of a chemokine in Chitosan (Ch/Poly(γ-glutamic acid (γ-PGA complexes. Ch is a non-toxic, cationic polysaccharide widely investigated. γ-PGA is a hydrophilic, non-toxic, biodegradable and negatively charged poly-amino acid. Ch and γ-PGA, being oppositely charged, can be combined through electrostatic interactions. These biocompatible structures can be used as carriers for active substances and can be easily modulated in order to control the delivery of drugs, proteins, DNA, etc.Using the layer-by-layer method, Ch and γ-PGA were assembled into polyelectrolyte multilayers films (PEMs with thickness of 120 nm. The chemokine stromal-derived factor-1 (SDF-1 was incorporated in these complexes and was continuously released during 120 h. The method of SDF-1 incorporation is of crucial importance for polymers assembly into PEMs and for the release kinetics of this chemokine. The Ch/γ-PGA PEMs with SDF-1 were able to recruit hMSCs, increasing the cell migration up to 6 fold to a maximum of 16.2 ± 4.9 cells/mm2. The controlled release of SDF-1 would be of great therapeutic value in the process of hMSC homing to injured tissues. This is the first study suggesting Ch/γ-PGA PEMs as SDF-1 reservoirs to recruit hMSCs, describing an efficient method of chemokine incorporation that allows a sustained released up to 5 days and that can be easily scaled-up.

  15. Linear Viscoelasticity and Swelling of Polyelectrolyte Complex Coacervates

    Science.gov (United States)

    Hamad, Fawzi; Colby, Ralph

    2012-02-01

    The addition of near equimolar amounts of poly(diallyldimethylammonium chloride) to poly(isobutylene-alt-maleate sodium), results in formation of a polyelectrolyte complex coacervate. Zeta-potential titrations conclude that these PE-complexes are nearly charge-neutral. Swelling and rheological properties are studied at different salt concentrations in the surrounding solution. The enhanced swelling observed at high salt concentration suggests the system behaves like a polyampholyte gel, and weaker swelling at very low salt concentrations implies polyelectrolyte gel behavior. Linear viscoelastic oscillatory shear measurements indicate that the coacervates are viscoelastic liquids and that increasing ionic strength of the medium weakens the electrostatic interactions between charged units, lowering the relaxation time and viscosity. We use the time-salt superposition idea recently proposed by Spruijt, et al., allowing us to construct master curves for these soft materials. Similar swelling properties observed when varying molecular weights. Rheological measurements reveal that PE-complexes with increasing molecular weight polyelectrolytes form a network with higher crosslink density, suggesting time-molecular weight superposition idea.

  16. Complexation behavior of oppositely charged polyelectrolytes: Effect of charge distribution

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Mingtian; Li, Baohui, E-mail: dliang@pku.edu.cn, E-mail: baohui@nankai.edu.cn [School of Physics and Key Laboratory of Functional Polymer Materials of Ministry of Education, Nankai University, Tianjin 300071 (China); Zhou, Jihan; Su, Cuicui; Niu, Lin; Liang, Dehai, E-mail: dliang@pku.edu.cn, E-mail: baohui@nankai.edu.cn [Beijing National Laboratory for Molecular Sciences and the Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2015-05-28

    Complexation behavior of oppositely charged polyelectrolytes in a solution is investigated using a combination of computer simulations and experiments, focusing on the influence of polyelectrolyte charge distributions along the chains on the structure of the polyelectrolyte complexes. The simulations are performed using Monte Carlo with the replica-exchange algorithm for three model systems where each system is composed of a mixture of two types of oppositely charged model polyelectrolyte chains (EGEG){sub 5}/(KGKG){sub 5}, (EEGG){sub 5}/(KKGG){sub 5}, and (EEGG){sub 5}/(KGKG){sub 5}, in a solution including explicit solvent molecules. Among the three model systems, only the charge distributions along the chains are not identical. Thermodynamic quantities are calculated as a function of temperature (or ionic strength), and the microscopic structures of complexes are examined. It is found that the three systems have different transition temperatures, and form complexes with different sizes, structures, and densities at a given temperature. Complex microscopic structures with an alternating arrangement of one monolayer of E/K monomers and one monolayer of G monomers, with one bilayer of E and K monomers and one bilayer of G monomers, and with a mixture of monolayer and bilayer of E/K monomers in a box shape and a trilayer of G monomers inside the box are obtained for the three mixture systems, respectively. The experiments are carried out for three systems where each is composed of a mixture of two types of oppositely charged peptide chains. Each peptide chain is composed of Lysine (K) and glycine (G) or glutamate (E) and G, in solution, and the chain length and amino acid sequences, and hence the charge distribution, are precisely controlled, and all of them are identical with those for the corresponding model chain. The complexation behavior and complex structures are characterized through laser light scattering and atomic force microscopy measurements. The order

  17. Complexation behavior of oppositely charged polyelectrolytes: Effect of charge distribution

    International Nuclear Information System (INIS)

    Complexation behavior of oppositely charged polyelectrolytes in a solution is investigated using a combination of computer simulations and experiments, focusing on the influence of polyelectrolyte charge distributions along the chains on the structure of the polyelectrolyte complexes. The simulations are performed using Monte Carlo with the replica-exchange algorithm for three model systems where each system is composed of a mixture of two types of oppositely charged model polyelectrolyte chains (EGEG)5/(KGKG)5, (EEGG)5/(KKGG)5, and (EEGG)5/(KGKG)5, in a solution including explicit solvent molecules. Among the three model systems, only the charge distributions along the chains are not identical. Thermodynamic quantities are calculated as a function of temperature (or ionic strength), and the microscopic structures of complexes are examined. It is found that the three systems have different transition temperatures, and form complexes with different sizes, structures, and densities at a given temperature. Complex microscopic structures with an alternating arrangement of one monolayer of E/K monomers and one monolayer of G monomers, with one bilayer of E and K monomers and one bilayer of G monomers, and with a mixture of monolayer and bilayer of E/K monomers in a box shape and a trilayer of G monomers inside the box are obtained for the three mixture systems, respectively. The experiments are carried out for three systems where each is composed of a mixture of two types of oppositely charged peptide chains. Each peptide chain is composed of Lysine (K) and glycine (G) or glutamate (E) and G, in solution, and the chain length and amino acid sequences, and hence the charge distribution, are precisely controlled, and all of them are identical with those for the corresponding model chain. The complexation behavior and complex structures are characterized through laser light scattering and atomic force microscopy measurements. The order of the apparent weight-averaged molar

  18. Complexation behavior of oppositely charged polyelectrolytes: Effect of charge distribution

    Science.gov (United States)

    Zhao, Mingtian; Zhou, Jihan; Su, Cuicui; Niu, Lin; Liang, Dehai; Li, Baohui

    2015-05-01

    Complexation behavior of oppositely charged polyelectrolytes in a solution is investigated using a combination of computer simulations and experiments, focusing on the influence of polyelectrolyte charge distributions along the chains on the structure of the polyelectrolyte complexes. The simulations are performed using Monte Carlo with the replica-exchange algorithm for three model systems where each system is composed of a mixture of two types of oppositely charged model polyelectrolyte chains (EGEG)5/(KGKG)5, (EEGG)5/(KKGG)5, and (EEGG)5/(KGKG)5, in a solution including explicit solvent molecules. Among the three model systems, only the charge distributions along the chains are not identical. Thermodynamic quantities are calculated as a function of temperature (or ionic strength), and the microscopic structures of complexes are examined. It is found that the three systems have different transition temperatures, and form complexes with different sizes, structures, and densities at a given temperature. Complex microscopic structures with an alternating arrangement of one monolayer of E/K monomers and one monolayer of G monomers, with one bilayer of E and K monomers and one bilayer of G monomers, and with a mixture of monolayer and bilayer of E/K monomers in a box shape and a trilayer of G monomers inside the box are obtained for the three mixture systems, respectively. The experiments are carried out for three systems where each is composed of a mixture of two types of oppositely charged peptide chains. Each peptide chain is composed of Lysine (K) and glycine (G) or glutamate (E) and G, in solution, and the chain length and amino acid sequences, and hence the charge distribution, are precisely controlled, and all of them are identical with those for the corresponding model chain. The complexation behavior and complex structures are characterized through laser light scattering and atomic force microscopy measurements. The order of the apparent weight-averaged molar

  19. Effect of Polyelectrolyte Stiffness and Solution pH on the Nanostructure of Complexes Formed by Cationic Amphiphiles and Negatively Charged Polyelectrolytes.

    Science.gov (United States)

    Ram-On, Maor; Cohen, Yachin; Talmon, Yeshayahu

    2016-07-01

    The interaction between amphiphiles and polyelectrolytes has been widely investigated in recent years due to their potential application in industry and medicine, with special focus on gene therapy. The cationic lipid dioleoyl trimethylammonium propane, DOTAP, and the oppositely charged polyelectrolytes, sodium poly(acrylic acid) and sodium poly(styrenesulfonate), form multilamellar complexes in water. Because of the different molecular stiffness of the two polyelectrolytes, they form different nanostructured complexes. Also, because of the different ionization behavior of the two polyelectrolytes, pH differently affects the complexation of the polyelectrolytes with didodecyldimethylammonium bromide (DDAB), another cationic surfactant. We used cryogenic temperature transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS) to compare the nanostructures formed. Our results show that although the basic nanostructures of the complexes are always lamellar (multilamellar or unilamellar) the morphology of the complexes is affected by the polyelectrolyte rigidity and the solution pH. PMID:27049758

  20. Catalytically active cobalt and copper complexes in polyelectrolyte multilayer films

    International Nuclear Information System (INIS)

    In this work an approach to obtain effective and easy reusable heterogeneous catalyst, LbL deposition of polyelectrolytes followed by covalently binding with cobalt (II) and copper (II) ions were described. Immobilization of metal complexes via covalent attachment to insoluble template is an attractive method to facilitate catalyst recovery, recycling. The reaction in the heterogeneous catalysis goes in the interface of catalyst and reaction solution and it is important to create a catalyst with large surface area. We have used polycations as polyethyleneimine (BPEI), quaternized poly(4- vynilpyridine) (QPVP) and polyanions as poly(acrylic acid) (PAA), poly(styrene sulphonate) sodium salt (PSS) and the electrostatic layer-by-layer assembly technique to make uniform thin film coating on SiO2 nanoparticles and glass slides with controllable thickness, roughness and mechanically durability. The stability of metals within multilayers in reaction condition were tested. We compared the amount of metal in PEMs of different polyelectrolytes. The stability constants of complex forming processes of the polymer-metal complexes in water and in alcohol were calculated by modified method of Bjerrum. Catalytic activity of immobilized catalysts was investigated for oxidation of toluene by molecular oxygen. Catalysts were separated from reaction mixture easily and had been used for this reaction five times without significant loss of activity. Key words: catalysis, layer-by-layer (LbL), polymer-metal complexes, oxidation, cobalt and copper immobilization

  1. Formation of Soft Nanoparticles via Polyelectrolyte Complexation: A Viscometric Study

    Directory of Open Access Journals (Sweden)

    Rondon Céline

    2014-05-01

    Full Text Available This paper describes the formation of soft nanoparticles resulting from electrostatically driven complexation of oppositely charged polyelectrolytes. The system was composed of a strong polyanion (polystyrene sulfonate, PSS and a weak polycation (poly(allylamine hydrochloride, PAH in large excess. Soft nanoparticles were obtained by pouring a PSS solution into a PAH one under constant stirring. The polyelectrolyte complexes (PEC were characterized through a viscometric study complemented by Dynamic Light Scattering (DLS, electrophoretic mobility and suspension turbidity measurements. PEC suspensions were centrifuged and by measuring the viscosity of the supernatant, we were able to estimate the free polycation concentration and hence the percentage of complexed polycation. We also measured the relative viscosity of the suspensions; from the estimated contribution of the PEC particles and of the polycation in excess, the average particle volume fraction was estimated. From all viscometric data, we could derive the evolution of the binding stoichiometry in PEC and of the effective particle volume fraction as a function of the mixing ratio (ratio of the cationic to anionic groups and of the pH. Our results emphasize the importance of charge accessibility in controlling both the stoichiometry and packing density of the complexes.

  2. Polyelectrolyte complexes : Preparation, characterization, and use for control of wet and dry adhesion between surfaces

    OpenAIRE

    Ankerfors, Caroline

    2012-01-01

    This thesis examines polyelectrolyte complex (PEC) preparation, adsorption behaviour, and potential use for control of wet and dry adhesion between surfaces. PEC formation was studied using a jet-mixing method not previously used for mixing polyelectrolytes. The PECs were formed using various mixing times, and the results were compared with those for PECs formed using the conventional polyelectrolyte titration method. The results indicated that using the jet mixer allowed the size of the form...

  3. Microgels polyelectrolytes

    OpenAIRE

    Kleinen, Jochen

    2012-01-01

    The formation of complexes from oppositely charged polyelectrolytes are well known. Polyelectrolytes bind to surfaces and can thus be used as flocculants or coating to modify surfaces. Layer-by-layer technique allows tailor made modification of surfaces as well as encapsulation. The modification of inorganic, rigid nanoparticles with polyelectrolytes is an established method while little is known about the modification of porous gel particles with polyelectrolytes. The gel particles are of co...

  4. Polyelectrolyte Complexation: A Field-Theoretic Description of Phase Behavior

    Science.gov (United States)

    Audus, Debra; Fredrickson, Glenn

    2010-03-01

    Our research focuses on a type of polyelectrolyte complexation called complex coacervation where two oppositely charged polymers in solution phase separate to form a dense polymer phase, known as the coacervate, and a supernatant, which typically has very low concentrations of polymer. To understand the effects of various parameters on coacervation, we previously developed a simple analytic theory for flexible polymers and small ions, which reproduces many general experimental trends. However, this theory is only valid for symmetric oppositely charged polymers, which limits its direct applicability to many experimental systems. Consequently, we have extended this theory to describe more complicated experimental systems where salt concentrations are high, pH equilibria shift with the complexation process, polymer concentrations are highly asymmetric, and counterion condensation may play an important role. To validate the modified theory, we compare our predictions with an exhaustive study of the phase behavior of polyacrylic acid and polyallylamine hydrochloride.

  5. Preparation and adsorption of refined polyelectrolyte complex nanoparticles.

    Science.gov (United States)

    Reihs, T; Müller, M; Lunkwitz, K

    2004-03-01

    We report on bulk and surface properties of centrifuged nonstoichiometric polyelectrolyte complex (PEC) dispersions. PECs were prepared by mixing poly(diallyldimethylammonium chloride) (PDADMAC) and sodium poly(maleic acid-co-alpha-methylstyrene) (PMA-MS) at the monomolar mixing ratio of 0.6 and polymer concentration >/=1 mmol/l. Centrifugation of initial PEC dispersions revealed three phases: supernatant (SUP), coacervate (COAC), and an insoluble precipitate. Mass, turbidity, particle hydrodynamic radii (R(h)), and the titratable charge amount were determined for those phases. The turbid COAC phase consisted of 200-nm nanoparticles and carried 60% of the polymer mass and 20% of the titratable charge amount of the initial PEC dispersion. The SUP phase showed no turbidity and no such nanoparticles, but carried 80% of the initial titratable charge amount, presumably caused by excess polycations. Furthermore, linear dependences of turbidity and R(h) on COAC concentration was observed. COAC adsorption was studied at polyelectrolyte multilayer (PEM) modified silicon surfaces in dependence on both adsorption time and concentration using attenuated total-reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The adsorption data were fitted by the simple Langmuir model. Comparison of COAC particles and polystyrene latices revealed similar adsorption features. SEM and AFM measurements resulted in hemispherically shaped adsorbed COAC particles with coverages >/=25%, whose calculated volumes correlated well with those in dispersion obtained by PCS. PMID:14757079

  6. SANS study on the complex of cationic micelles and anionic polyelectrolytes

    International Nuclear Information System (INIS)

    We investigated the complex of cationic micelles and anionic polyelectrolytes. The cationic micelles have the composition of nonionic surfactant, Octa-ethyleneglycol mono n-tetradecyl ether (C14E8) and cationic surfactant, Tetradecyltrimethylammonium Bromide (TTAB), and the polyelectrolyte is Poly Styrene Sulfonic Acid, Sodium Salt (Mw.= 73900, PSS80k). By the charge interaction, they formed the complexes in the aqueous solution. This complex was studied by Small Angle Neutron Scattering (SANS). SANS study showed that the size distribution changed by the cationic surfactant-to-polyelectrolyte charge ratio. The structure of this complex was also studied

  7. Polyelectrolyte-complex nanostructured fibrous scaffolds for tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Devendra [Department of Civil Engineering, North Dakota State University, Fargo, ND 58105 (United States); Katti, Kalpana S., E-mail: Kalpana.Katti@ndsu.edu [Department of Civil Engineering, North Dakota State University, Fargo, ND 58105 (United States); Katti, Dinesh R. [Department of Civil Engineering, North Dakota State University, Fargo, ND 58105 (United States)

    2009-08-31

    In the current work, polyelectrolyte complex (PEC) fibrous scaffolds for tissue engineering have been synthesized and a mechanism of their formation has been investigated. The scaffolds are synthesized using polygalacturonic acid and chitosan using the freeze drying methodology. Highly interconnected pores of sizes in the range of 5-20 {mu}m are observed in the scaffolds. The thickness of the fibers was found to be in the range of 1-2 {mu}m. Individual fibers have a nanogranular structure as observed using AFM imaging. In these scaffolds, PEC nanoparticles assemble together at the interface of ice crystals during freeze drying process. Further investigation shows that the freezing temperature and concentration have a remarkable effect on structure of scaffolds. Biocompatibility studies show that scaffold containing chitosan, polygalacturonic acid and hydroxyapatite promotes cell adhesion and proliferation. On the other hand, cells on scaffolds fabricated without hydroxyapatite nanoparticles showed poor adhesion.

  8. Complex formation between polyelectrolytes and oppositely charged oligoelectrolytes

    Science.gov (United States)

    Zhou, Jiajia; Barz, Matthias; Schmid, Friederike

    2016-04-01

    We study the complex formation between one long polyanion chain and many short oligocation chains by computer simulations. We employ a coarse-grained bead-spring model for the polyelectrolyte chains and model explicitly the small salt ions. We systematically vary the concentration and the length of the oligocation and examine how the oligocations affects the chain conformation, the static structure factor, the radial and axial distribution of various charged species, and the number of bound ions in the complex. At low oligocation concentration, the polyanion has an extended structure. Upon increasing the oligocation concentration, the polyanion chain collapses and forms a compact globule, but the complex still carries a net negative charge. Once the total charge of the oligocations is equal to that of the polyanion, the collapse stops and is replaced by a slow expansion. In this regime, the net charge on the complexes is positive or neutral, depending on the microion concentration in solution. The expansion can be explained by the reduction of the oligocation bridging. We find that the behavior and the structure of the complex are largely independent of the length of oligocations, and very similar to that observed when replacing the oligocations by multivalent salt cations, and conclude that the main driving force keeping the complex together is the release of monovalent counterions and coions. We speculate on the implications of this finding for the problem of controlled oligolyte release and oligolyte substitution.

  9. Counterions release from electrostatic complexes of polyelectrolytes and proteins of opposite charge : a direct measurement

    OpenAIRE

    Gummel, Jérémie; Cousin, Fabrice; Boué, François

    2009-01-01

    Though often considered as one of the main driving process of the complexation of species of opposite charges, the release of counterions has never been experimentally directly measured on polyelectrolyte/proteins complexes. We present here the first structural determination of such a release by Small Angle Neutron Scattering in complexes made of lysozyme, a positively charged protein and of PSS, a negatively charged polyelectrolyte. Both components have the same neutron density length, so th...

  10. Thermal and pH Transitions in Polyelectrolyte Complexes and Multilayers

    Science.gov (United States)

    Lutkenhaus, Jodie

    2015-03-01

    When oppositely charged polymers are mixed in water, they form a polyelectrolyte complex. Analogously at a surface, oppositely charged polymers can be assembled to form a polyelectrolyte multilayer. Complexation is entropically driven, as it results in the release of small counter ions and water molecules into the surrounding media. First, the effect of time and temperature on the formation of polyelectrolyte complexes containing model polyelectrolytes poly(diallyldimethyl ammonium chloride) and poly(styrene sulfonate) is presented. We show that complexation is a time-dependent phenomena, which is consistent with complexes existing in a kinetically trapped state, rather than a thermodynamic equilibrium. Upon heating, a glassy-viscous transition that shows features of an LCST is demonstrated. Second, the effect of pH on polyelectrolyte multilayer microtubes is presented. The microtubes are made of poly(allylamine) and poly(acrylic acid), both of which are weak polyelectrolytes. Modulating the pH induces a nanoporous transition that results in nanoporous microtubes. These results, in summary, show that noncovalent interactions are very sensitive to external stimuli such as temperature and pH.

  11. Soft microcapsules with highly plastic shells formed by interfacial polyelectrolyte-nanoparticle complexation.

    Science.gov (United States)

    Kaufman, Gilad; Nejati, Siamak; Sarfati, Raphael; Boltyanskiy, Rostislav; Loewenberg, Michael; Dufresne, Eric R; Osuji, Chinedum O

    2015-10-14

    Composite microcapsules have been aggressively pursued as designed chemical entities for biomedical and other applications. Common preparations rely on multi-step, time consuming processes. Here, we present a single-step approach to fabricate such microcapsules with shells composed of nanoparticle-polyelectrolyte and protein-polyelectrolyte complexes, and demonstrate control of the mechanical and release properties of these constructs. Interfacial polyelectrolyte-nanoparticle and polyelectrolyte-protein complexation across a water-oil droplet interface results in the formation of capsules with shell thicknesses of a few μm. Silica shell microcapsules exhibited a significant plastic response at small deformations, whereas lysozyme incorporated shells displayed a more elastic response. We exploit the plasticity of nanoparticle incorporated shells to produce microcapsules with high aspect ratio protrusions by micropipette aspiration. PMID:26169689

  12. Complexation of oppositely charged polyelectrolytes in gene delivery and biology

    Science.gov (United States)

    Shklovskii, Boris

    2009-03-01

    Charge inversion of a DNA double helix by a positively charged flexible polymer (polyelectrolyte) is widely used to facilitate DNA contact with negative cell membranes for gene delivery. Motivated by this application in the first part of the talk I study the phase diagram a solution of long polyanions (PA) with a shorter polycations (PC) as a function the ratio of total charges of PC and PA in the solution, x, and the concentration of monovalent salt. Each PA attracts many PCs to form a complex. When x= 1, the complexes are neutral and condense in a macroscopic drop. When x is far away from 1, complexes are strongly charged and stable. PA are overcharged by PC at x > 1 and undercharged by PC at x vegetable viruses from long ss-RNA molecule paying role of scaffold and identical capsid proteins with long positive tails. I show that optimization Coulomb energy of the virus leads to the charge of RNA twice larger than the total charge of the capsid, in agreement with the experimental data. Then I discuss kinetics of the Coulomb complexation driven virus self-assembly. Capsid proteins stick to unassembled chain of ss RNA (which we call ``antenna'') and slide on it towards the assembly site. I show that at excess of capsid proteins such one-dimensional diffusion accelerates self-assembly more than ten times. On the other hand at excess of ss-RNA, antenna slows self-assembly down. Several experiments are proposed to verify the role of ss-RNA antenna in self-assembly.

  13. Complexation and coacervation of like-charged polyelectrolytes inspired by mussels.

    Science.gov (United States)

    Kim, Sangsik; Huang, Jun; Lee, Yongjin; Dutta, Sandipan; Yoo, Hee Young; Jung, Young Mee; Jho, YongSeok; Zeng, Hongbo; Hwang, Dong Soo

    2016-02-16

    It is well known that polyelectrolyte complexes and coacervates can form on mixing oppositely charged polyelectrolytes in aqueous solutions, due to mainly electrostatic attraction between the oppositely charged polymers. Here, we report the first (to the best of our knowledge) complexation and coacervation of two positively charged polyelectrolytes, which provides a new paradigm for engineering strong, self-healing interactions between polyelectrolytes underwater and a new marine mussel-inspired underwater adhesion mechanism. Unlike the conventional complex coacervate, the like-charged coacervate is aggregated by strong short-range cation-π interactions by overcoming repulsive electrostatic interactions. The resultant phase of the like-charged coacervate comprises a thin and fragile polyelectrolyte framework and round and regular pores, implying a strong electrostatic correlation among the polyelectrolyte frameworks. The like-charged coacervate possesses a very low interfacial tension, which enables this highly positively charged coacervate to be applied to capture, carry, or encapsulate anionic biomolecules and particles with a broad range of applications.

  14. Complexation and coacervation of like-charged polyelectrolytes inspired by mussels

    Science.gov (United States)

    Kim, Sangsik; Huang, Jun; Lee, Yongjin; Dutta, Sandipan; Yoo, Hee Young; Jung, Young Mee; Jho, YongSeok; Zeng, Hongbo

    2016-01-01

    It is well known that polyelectrolyte complexes and coacervates can form on mixing oppositely charged polyelectrolytes in aqueous solutions, due to mainly electrostatic attraction between the oppositely charged polymers. Here, we report the first (to the best of our knowledge) complexation and coacervation of two positively charged polyelectrolytes, which provides a new paradigm for engineering strong, self-healing interactions between polyelectrolytes underwater and a new marine mussel-inspired underwater adhesion mechanism. Unlike the conventional complex coacervate, the like-charged coacervate is aggregated by strong short-range cation–π interactions by overcoming repulsive electrostatic interactions. The resultant phase of the like-charged coacervate comprises a thin and fragile polyelectrolyte framework and round and regular pores, implying a strong electrostatic correlation among the polyelectrolyte frameworks. The like-charged coacervate possesses a very low interfacial tension, which enables this highly positively charged coacervate to be applied to capture, carry, or encapsulate anionic biomolecules and particles with a broad range of applications. PMID:26831090

  15. Complex coacervation: A field theoretic simulation study of polyelectrolyte complexation

    Science.gov (United States)

    Lee, Jonghoon; Popov, Yuri O.; Fredrickson, Glenn H.

    2008-06-01

    Using the complex Langevin sampling strategy, field theoretic simulations are performed to study the equilibrium phase behavior and structure of symmetric polycation-polyanion mixtures without salt in good solvents. Static structure factors for the segment density and charge density are calculated and used to study the role of fluctuations in the electrostatic and chemical potential fields beyond the random phase approximation. We specifically focus on the role of charge density and molecular weight on the structure and complexation behavior of polycation-polyanion solutions. A demixing phase transition to form a ``complex coacervate'' is observed in strongly charged systems, and the corresponding spinodal and binodal boundaries of the phase diagram are investigated.

  16. Underwater contact adhesion and microarchitecture in polyelectrolyte complexes actuated by solvent exchange

    Science.gov (United States)

    Zhao, Qiang; Lee, Dong Woog; Ahn, B. Kollbe; Seo, Sungbaek; Kaufman, Yair; Israelachvili, Jacob N.; Waite, J. Herbert

    2016-04-01

    Polyelectrolyte complexation is critical to the formation and properties of many biological and polymeric materials, and is typically initiated by aqueous mixing followed by fluid-fluid phase separation, such as coacervation. Yet little to nothing is known about how coacervates evolve into intricate solid microarchitectures. Inspired by the chemical features of the cement proteins of the sandcastle worm, here we report a versatile and strong wet-contact microporous adhesive resulting from polyelectrolyte complexation triggered by solvent exchange. After premixing a catechol-functionalized weak polyanion with a polycation in dimethyl sulphoxide (DMSO), the solution was applied underwater to various substrates whereupon electrostatic complexation, phase inversion, and rapid setting were simultaneously actuated by water-DMSO solvent exchange. Spatial and temporal coordination of complexation, inversion and setting fostered rapid (~25 s) and robust underwater contact adhesion (Wad >= 2 J m-2) of complexed catecholic polyelectrolytes to all tested surfaces including plastics, glasses, metals and biological materials.

  17. The Effect of Salt on the Complex Coacervation of Vinyl Polyelectrolytes

    Directory of Open Access Journals (Sweden)

    Sarah L. Perry

    2014-06-01

    Full Text Available Complex coacervation is an electrostatically-driven phase separation phenomenon that is utilized in a wide range of everyday applications and is of great interest for the creation of self-assembled materials. Here, we utilized turbidity to characterize the effect of salt type on coacervate formation using two vinyl polyelectrolytes, poly(acrylic acid sodium salt (pAA and poly(allylamine hydrochloride (pAH, as simple models for industrial and biological coacervates. We confirmed the dominant role of salt valence on the extent of coacervate formation, while demonstrating the presence of significant secondary effects, which can be described by Hofmeister-like behavior. These results revealed the importance of ion-specific interactions, which are crucial for the informed design of coacervate-based materials for use in complex ionic environments, and can enable more detailed theoretical investigations on the role of subtle electrostatic and thermodynamic effects in complex coacervation.

  18. Polymer Physics Prize Lecture: Polyelectrolyte complexes: New routes to useful soft materials

    Science.gov (United States)

    Tirrell, Matthew

    2012-02-01

    Mixtures of oppositely charged polyelectrolytes may form precipitates (phase-separated solids) or coacervates (phase-separated fluids). Coacervates have been known for a long time to have interesting properties such as very low interfacial tension with water and a resultant ability to coat surfaces, engulf particles and invade porous media. Most prior work on coacervate complexes has been done with structurally complex (e.g., gum Arabic), biologically derived macromolecules (e.g., gelation). Our work is focusing on phase behavior and self-assembly in classes of structurally simpler polymers. Polypeptides are one such class, where we can produce anionic, cationic and neutral, water-soluble polymers all with the some backbone and varying in small side-group structures. We are able to demonstrate very general patterns in phase behavior over different members of this class of polymers. Coacervate formation is the rule rather than the exception in these materials, with such formation quite strongly peaked at balanced stoichiometry of the polyelectrolyte components. One molar salt is usually sufficient to dissolve the coacervate phases that form. Block copolymer mixtures containing oppositely charged blocks can form self-assembled structures: micelles with diblocks and hydrogels with triblocks. The structure and properties of these assemblies can be tuned based on knowledge of the bulk phase behavior response to molecular weight, stoichiometry and salt concentration. Examples of phase behavior and structure-property relationship will be discussed.

  19. Polyelectrolyte complex nanoparticles from cationised gelatin and sodium alginate for curcumin delivery.

    Science.gov (United States)

    Sarika, P R; James, Nirmala Rachel

    2016-09-01

    Self assembled hybrid polyelectrolyte complex (PEC) nanoparticles are prepared from cationically modified gelatin and sodium alginate (Alg) by electrostatic complexation between the polymers. Cationised gelatin (CG) is prepared by the reaction of gelatin with ethylenediamine. Structural changes in gelatin, after modification with ethylenediamine are investigated by XRD and (1)H NMR spectroscopy. Hybrid polyelectrolyte nanoparticles, labeled CG/Alg, are prepared by simple mixing of CG and Alg. CG/Alg complex shows spherical morphology as confirmed by scanning electron microscopy. These polyelectrolyte complex nanoparticles can be used for the encapsulation and delivery of natural antioxidant curcumin to carcinoma cells. CG/Alg nanoparticles show curcumin encapsulation efficiency of 69% and exhibit sustained release of curcumin in vitro. Anticancer activity of curcumin loaded CG/Alg nanoparticles towards MCF-7 cells is disclosed by MTT assay. Intracellular uptake of the drug encapsulated nanoparticles is confirmed by fluorescent imaging. PMID:27185149

  20. Effect of monovalent salt on the conformation of polyelectrolyte-surfactant complexes

    Science.gov (United States)

    Diehl, A.; Kuhn, P. S.

    2009-01-01

    We study the conformation of polyelectrolyte-surfactant complexes in the presence of monovalent salt. A simple model for the formation of these structures is presented in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, with the hydrophobic interactions between the hydrocarbon tails of surfactant molecules treated in the spirit of van der Waals theory as an effective attraction. The extension of the polyelectrolyte-surfactant complexes is analyzed as a function of the salt concentration and a discrete conformational transition between a compact globule and an elongated coil is found, in agreement with experimental results for the unfolding transition of a DNA-cationic surfactant complex.

  1. Polyelectrolyte complexes: A review of their applicability in drug delivery technology

    Directory of Open Access Journals (Sweden)

    Lankalapalli S

    2009-01-01

    Full Text Available Over the past several years, great advances have been made towards novel drug delivery systems. The phenomena of interpolymer interactions and formation of polyelectrolyte complexes have been the focus of intensive fundamental and applied research. Interpolyelectrolyte complexes combine unique physicochemical properties with high biocompatibility. Studies have been carried out on many different polymer blends and types. Such combinations may possess unique properties that are different from those of individual component. The present review emphasizes on the applicability of polyelectrolyte complexes in drug delivery technology.

  2. Complexation between oppositely charged polyelectrolytes: beyond the Random Phase Approximation

    OpenAIRE

    Castelnovo, Martin; Joanny, Jean-Francois

    2001-01-01

    We consider the phase behavior of polymeric systems by calculating the structure factors beyond the Random Phase Approximation. The effect of this correction to the mean-field RPA structure factor is shown to be important in the case of coulombic systems. Two examples are given: simple electrolytes and mixtures of incompatible oppositely charged polyelectrolytes. In this last case, all former studies predicted an enhancement of compatibility for increasing charge densities; we also describe t...

  3. Cationic and anionic polyelectrolyte complexes of xylan and chitosan. Interaction with lignocellulosic surfaces.

    Science.gov (United States)

    Mocchiutti, Paulina; Schnell, Carla N; Rossi, Gerardo D; Peresin, María S; Zanuttini, Miguel A; Galván, María V

    2016-10-01

    Cationic (CatPECs) and anionic (AnPECs) polyelectrolyte complexes from xylan and chitosan were formed, characterized and adsorbed onto unbleached fibers for improving the papermaking properties. They were prepared at a level of 30% of neutralization charge ratio by modifying the order of addition of polyelectrolytes and the ionic strength (0.01N and 0.1N NaCl). The charge density, colloidal stability and particle size of polyelectrolyte complexes (PECs) was measured using polyelectrolyte titration method, Turbiscan and Zetasizer Nano equipments, respectively. All the complexes were stable even after seven days from PEC formation. DRIFT spectra of complexes were also analyzed. The adsorption behavior of them onto cellulose nanofibrils model surfaces was studied using quartz crystal microbalance with dissipation monitoring, and surface plasmon resonance. It was found that the PEC layers were viscoelastic and highly hydrated. Finally, it is shown that the adsorbed PECs onto cellulosic fibers markedly improved the tensile and crushing strengths of paper. PMID:27312617

  4. Polyelectrolyte Properties in Mono and Multi-Valent Ionic Media: Brushes and Complex Coacervates

    Science.gov (United States)

    Farina, Robert M.

    Materials composed of polyelectrolytes have unique and interesting physical properties resulting primarily from their charged monomer segments. Polyelectrolytes, which exist in many different biological and industrial forms, have also been shown to be highly responsive to external environmental changes. Here, two specific polyelectrolyte systems, brushes and complex coacervates, are discussed in regards to how their properties can be tailored by adjusting the surrounding ionic environment with mono and multi-valent ions. End-tethered polyelectrolyte brushes, which constitute an interesting and substantial portion of polyelectrolyte applications, are well known for their ability to provide excellent lubrication and low friction when coated onto surfaces (e.g. articular cartilage and medical devices), as well as for their ability to stabilize colloidal particles in solution (e.g. paint and cosmetic materials). These properties have been extensively studied with brushes in pure mono-valent ionic media. However, polyelectrolyte brush interactions with multi-valent ions in solution are much less understood, although highly relevant considering mono and multi-valent counterions are present in most applications. Even at very low concentrations of multi-valent ions in solution, dramatic polyelectrolyte brush physical property changes can occur, resulting in collapsed chains which also adhere to one another via multi-valent bridging. Here, the strong polyelectrolyte poly(sodium styrene sulfonate) was studied using the Surface Forces Apparatus (SFA) and electrochemistry in order to investigate brush height and intermolecular interactions between two brushes as a function of multi-valent counterion population inside a brush. Complex coacervates are formed when polyanions and polycations are mixed together in proper conditions of an aqueous solution. This mixing results in a phase separation of a polymer-rich, coacervate phase composed of a chain network held together via

  5. Interaction between immobilized polyelectrolyte complex nanoparticles and human mesenchymal stromal cells

    Directory of Open Access Journals (Sweden)

    Woltmann B

    2014-05-01

    Full Text Available Beatrice Woltmann,1 Bernhard Torger,2,3 Martin Müller,2,3,* Ute Hempel1,*1Dresden University of Technology, Faculty of Medicine Carl Gustav Carus, Institute of Physiological Chemistry, Dresden, Germany; 2Leibniz Institute of Polymer Research Dresden, Department of Polyelectrolytes and Dispersions, Dresden, Germany; 3Dresden University of Technology, Department of Chemistry and Food Chemistry, Dresden, Germany*These authors contributed equally to this workBackground: Implant loosening or deficient osseointegration is a major problem in patients with systemic bone diseases (eg, osteoporosis. For this reason, the stimulation of the regional cell population by local and sustained drug delivery at the bone/implant interface to induce the formation of a mechanical stable bone is promising. The purpose of this study was to investigate the interaction of polymer-based nanoparticles with human bone marrow-derived cells, considering nanoparticles’ composition and surface net charge.Materials and methods: Polyelectrolyte complex nanoparticles (PECNPs composed of the polycations poly(ethyleneimine (PEI, poly(L-lysine (PLL, or (N,N-diethylaminoethyldextran (DEAE in combination with the polyanions dextran sulfate (DS or cellulose sulfate (CS were prepared. PECNPs’ physicochemical properties (size, net charge were characterized by dynamic light scattering and particle charge detector measurements. Biocompatibility was investigated using human mesenchymal stromal cells (hMSCs cultured on immobilized PECNP films (5–50 nmol·cm-2 by analysis for metabolic activity of hMSCs in dependence of PECNP surface concentration by MTS (3-[4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium, inner salt assay, as well as cell morphology (phase contrast microscopy.Results: PECNPs ranging between ~50 nm and 150 nm were prepared. By varying the ratio of polycations and polyanions, PECNPs with a slightly positive (PEC+NP or negative (PEC

  6. Confined polyelectrolytes: The complexity of a simple system.

    Science.gov (United States)

    Nunes, Sandra C C; Skepö, Marie; Pais, Alberto A C C

    2015-08-01

    The interaction between polyelectrolytes and counterions in confined situations and the mutual relationship between chain conformation and ion condensation is an important issue in several areas. In the biological field, it assumes particular relevance in the understanding of the packaging of nucleic acids, which is crucial in the design of gene delivery systems. In this work, a simple coarse-grained model is used to assess the cooperativity between conformational change and ion condensation in spherically confined backbones, with capsides permeable to the counterions. It is seen that the variation on the degree of condensation depends on counterion valence. For monovalent counterions, the degree of condensation passes through a minimum before increasing as the confining space diminishes. In contrast, for trivalent ions, the overall tendency is to decrease the degree of condensation as the confinement space also decreases. Most of the particles reside close to the spherical wall, even for systems in which the density is higher closer to the cavity center. This effect is more pronounced, when monovalent counterions are present. Additionally, there are clear variations in the charge along the concentric layers that cannot be totally ascribed to polyelectrolyte behavior, as shown by decoupling the chain into monomers. If both chain and counterions are confined, the formation of a counterion rich region immediately before the wall is observed. Spool and doughnut-like structures are formed for stiff chains, within a nontrivial evolution with increasing confinement. PMID:26096545

  7. New nanocomposites based on layered aluminosilicate and guanidine containing polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Khashirov, Azamat A.; Zhansitov, Azamat A.; Khashirova, Svetlana Yu. [Kabardino-Balkarian State University a. Kh.M. Berbekov, 173 Chernyshevskogo st., 360004, Nalchik (Russian Federation); Zaikov, Genadiy E. [N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 4, Kosygin St., 119991, Moscow (Russian Federation)

    2014-05-15

    The new functional nanomaterials based on layered aluminosilicate and guanidine containing polyelectrolytes combining high bactericidal activity with an increased ability to bind to heavy metals and organic pollutants were received. To prove the chemical structure of the model compounds (zwitterionic delocalized resonance structures AG/MAG and PAG/PMAG), as well as the presence of such structures in nanocomposites received on their basis and the MMT, IR, {sup 1}H NMR spectroscopy, X-ray diffraction studies and nanoindentation/sclerometry followed by scanning the surface in the area of the indentation were used.

  8. New nanocomposites based on layered aluminosilicate and guanidine containing polyelectrolytes

    International Nuclear Information System (INIS)

    The new functional nanomaterials based on layered aluminosilicate and guanidine containing polyelectrolytes combining high bactericidal activity with an increased ability to bind to heavy metals and organic pollutants were received. To prove the chemical structure of the model compounds (zwitterionic delocalized resonance structures AG/MAG and PAG/PMAG), as well as the presence of such structures in nanocomposites received on their basis and the MMT, IR, 1H NMR spectroscopy, X-ray diffraction studies and nanoindentation/sclerometry followed by scanning the surface in the area of the indentation were used

  9. Counterions release from electrostatic complexes of polyelectrolytes and proteins of opposite charge : a direct measurement

    CERN Document Server

    Gummel, Jérémie; Boué, François

    2009-01-01

    Though often considered as one of the main driving process of the complexation of species of opposite charges, the release of counterions has never been experimentally directly measured on polyelectrolyte/proteins complexes. We present here the first structural determination of such a release by Small Angle Neutron Scattering in complexes made of lysozyme, a positively charged protein and of PSS, a negatively charged polyelectrolyte. Both components have the same neutron density length, so their scattering can be switched off simultaneously in an appropriate "matching" solvent; this enables determination of the spatial distribution of the single counterions within the complexes. The counterions (including the one subjected to Manning condensation) are expelled from the cores where the species are at electrostatic stoichiometry.

  10. Alcohol--Induced Polyelectrolyte-Surfactant Complex Coacervate Systems: Characterization and Applications in Enzyme and Protein Extraction

    Science.gov (United States)

    Nejati Moshtaghin, Mahboubeh

    The focus of this thesis is to achieve a better understanding of the newly discovered surfactant-polyelectrolyte complex coacervate (SPCC) systems induced by fluoroalcohol/acid as well as short chain aliphatic alcohol; and to elucidate their applications in extraction and enrichment of proteins and enzyme. We have discovered that fluoroalcohols and --acids induce complex coacervation and phase separation in the aqueous mixtures of oppositely charged anionic polyelectrolytes; specifically, sodium salts of polyacrylic acid and polymethacrylic acid and cationic surfactant (cetyltrimethylammonium bromide, CTAB) over a broad range of concentrations of mole fractions of the oppositely charged amphiphiles. Accordingly, these new classes of coacervators will significantly broaden the scope and facilitate engineering of new coacervate phases. Toward these goals, we have inspected the formation of surfactant-polyelectrolyte complex coacervates in the presence of fluoroalcohols namely hexafluoroisopropanol (HFIP) and Trifluoroethanol (TFE). Furthermore, the extent of coacervation as a function of concentrations the system components, and charge ratios of the oppositely charged amphiphiles has been investigated. Polyelectrolytes are considered to be milder reagents, as compared to surfactants, regarding proteins denaturation. This highlights the importance of a detailed investigation of the efficiency of our coacervate systems for extraction and preconcentration of proteins and enzymes, especially, when the biological activity of the extracted proteins needs to be maintained based on the objectives mentioned above, the results of the investigations have been organized in four chapters. In Chapter II, the phase behavior of the FA-SPCC will be investigated. The objective is to examine the phase behavior and phase properties with respect to the extent of coacervation in different solution conditions. In particular, the effects of different solution variables such as concentration

  11. Finite size and inner structure controlled by electrostatic screening in globular complexes of proteins and polyelectrolytes

    OpenAIRE

    Gummel, Jérémie; Boué, François; Clemens, Daniel; Cousin, Fabrice

    2010-01-01

    International audience We present an extended structural study of globular complexes made by mixing a positively charge protein (lysozyme) and a negatively charged polyelectrolyte (PSS). We study the influence of all the parameters that may act on the structure of the complexes (charge densities and concentration of the species, partial hydrophobicity of the polyion chain, ionic strength). The structures on a 15 scale range lying from 10Å to 1000Å are measured by SANS. Whatever the conditi...

  12. Fracturing fluid cleanup by controlled release of enzymes from polyelectrolyte complex nanoparticles

    Science.gov (United States)

    Barati Ghahfarokhi, Reza

    Guar-based polymer gels are used in the oil and gas industry to viscosify fluids used in hydraulic fracturing of production wells, in order to reduce leak-off of fluids and pressure, and improve the transport of proppants. After fracturing, the gel and associated filter cake must be degraded to very low viscosities using breakers to recover the hydraulic conductivity of the well. Enzymes are widely used to achieve this but injecting high concentrations of enzyme may result in premature degradation, or failure to gel; denaturation of enzymes at alkaline pH and high temperature conditions can also limit their applicability. In this study, application of polyelectrolyte nanoparticles for entrapping, carrying, releasing and protecting enzymes for fracturing fluids was examined. The objective of this research is to develop nano-sized carriers capable of carrying the enzymes to the filter cake, delaying the release of enzyme and protecting the enzyme against pH and temperature conditions inhospitable to native enzyme. Polyethylenimine-dextran sulfate (PEI-DS) polyelectrolyte complexes (PECs) were used to entrap two enzymes commonly used in the oil industry in order to obtain delayed release and to protect the enzyme from conditions inhospitable to native enzyme. Stability and reproducibility of PEC nanoparticles was assured over time. An activity measurement method was used to measure the entrapment efficiency of enzyme using PEC nanoparticles. This method was confirmed using a concentration measurement method (SDS-PAGE). Entrapment efficiencies of pectinase and a commercial high-temperature enzyme mixture in polyelectrolyte complex nanoparticles were maximized. Degradation, as revealed by reduction in viscoelastic moduli of borate-crosslinked hydroxypropyl guar (HPG) gel by commercial enzyme loaded in polyelectrolyte nanoparticles, was delayed, compared to equivalent systems where the enzyme mixture was not entrapped. This indicates that PEC nanoparticles delay the

  13. Potential of mean force and transient states in polyelectrolyte pair complexation

    Science.gov (United States)

    Xu, Xiao; Kanduč, Matej; Wu, Jianzhong; Dzubiella, Joachim

    2016-07-01

    The pair association between two polyelectrolytes (PEs) of the same size but opposite charge is systematically studied in terms of the potential of mean force (PMF) along their center-of-mass reaction coordinate via coarse-grained, implicit-solvent, explicit-salt computer simulations. The focus is set on the onset and the intermediate transient stages of complexation. At conditions above the counterion-condensation threshold, the PE association process exhibits a distinct sliding-rod-like behavior where the polymer chains approach each other by first stretching out at a critical distance close to their contour length, then "shaking hand" and sliding along each other in a parallel fashion, before eventually folding into a neutral complex. The essential part of the PMF for highly charged PEs can be very well described by a simple theory based on sliding charged "Debye-Hückel" rods with renormalized charges in addition to an explicit entropy contribution owing to the release of condensed counterions. Interestingly, at the onset of complex formation, the mean force between the PE chains is found to be discontinuous, reflecting a bimodal structural behavior that arises from the coexistence of interconnected-rod and isolated-coil states. These two microstates of the PE complex are balanced by subtle counterion release effects and separated by a free-energy barrier due to unfavorable stretching entropy.

  14. POLYMER COLLOIDS FORMED BY POLYELECTROLYTE COMPLEXATION OF VINYL POLYMERS AND POLYSACCHARIDES IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Hui-dan Liu; Takahiro Sato

    2013-01-01

    The polyelectrolyte complex formed from the polyanion and polycation was studied by turbidimetry,static and electrophoretic light scattering,and elementary analysis.Sodium salts of polyacrylate (PA) and heparin (Hep) were chosen as the polyanion,and hydrochloric salts of poly(vinyl amine) (PVA) and chitosan (Chts) as the polycation.Although these vinyl polymers and polysaccharides have remarkably different backbone chemical structures and linear charge densities,all the four combinations PA-PVA,PA-Chts,Hep-PVA,and Hep-Chts provide almost stoichiometric polyelectrolyte complexes which are slightly charged owing to the adsorption of the excess polyelectrolyte component onto the neutral complex.The charges stabilize the complex colloids in aqueous solution of a non-stoichiometric mixture,and the aggregation number of the complex colloids increases with approaching to the stoichiometric mixing ratio.The mixing ratio dependence of the aggregation number for the four complexes is explained by the model proposed in the previous study.

  15. Polyelectrolyte Complex Hydrogels: Self-assembly and the Influence of Charged and Neutral Blocks

    Science.gov (United States)

    Srivastava, Samanvaya; Goldfeld, David; Levi, Adam; Mao, Jun; Chen, Wei; Tirrell, Matthew

    Polyelectrolyte complexes (PEC) form when oppositely charged polyelectrolyte chains spontaneously associate and phase separate in aqueous mediums. Bulk phase separation of the PECs can be evaded by combining one or both of the polyelectrolytes with a neutral polymer, thus engineering pathways for self-assembled PEC micelles and hydrogels. The PEC domains in these assemblies can encapsulate therapeutics as well as genetic materials and thus have tremendous potential in drug delivery and tissue engineering applications. We will present insights on the equilibrium structure and self-assembly kinetics of PEC hydrogels with large-scale ordering of the nanoscale PEC domains through detailed structure characterization and rheology studies of self-assembled materials comprising of functionalized polyallyl glycidyl ethers (PAGE) connected to either single poly(ethylene glycol) (PEG) chain to form diblock copolymers or as functionalized end-groups on a triblock copolymer with a PEG midblock. The effect of key parameters such as polymer concentration, polymer block lengths, salt, ionic strength, and degree of charge mismatch on the equilibrium materials properties will be discussed, with a special emphasis on the structure-defining role of the charged blocks and the structure-directing role of neutral blocks. Additionally, interesting similarities, and differences between structures and dynamics of hydrogels comprising diblock and corresponding triblock polyelectrolytes, respectively, will be discussed.

  16. Rapid polyelectrolyte-based membrane immunoassay for the herbicide butachlor.

    Science.gov (United States)

    Dzantiev, B B; Byzova, N A; Zherdev, A V; Hennion, M C

    2005-01-01

    Oppositely charged water-soluble polyelectrolytes were used in the developed membrane immunoenzyme assay for the herbicide butachlor. High-affinity and rapid binding between polyanion polymethacrylate and polycation poly(N-ethyl-4-vinylpyridinium) was applied to separate reacted and free immunoreactants. Competitive immunoassay format with peroxidase-labeled antigen was realized. The insoluble colored product of the peroxidase reaction was formed by bound labeled immune complexes and was reflectometrically detected. The assay combines short duration (15 min), high sensitivity (0.03 g/mL) and availability for out-of-laboratory testing. Different image processing algorithms were used to determine the herbicide content. Low variation coefficients of the measurements in the proposed quantitative assay, namely 4.8-9.0% for the range of antigen concentrations from 0.1 to 3.0 ng/mL, are evidence of the assay effectiveness. Possibility to control the butachlor content in mineral, artesian, and drinking water was demonstrated.

  17. Born energy, acid-base equilibrium, structure and interactions of end-grafted weak polyelectrolyte layers

    Energy Technology Data Exchange (ETDEWEB)

    Nap, R. J.; Tagliazucchi, M.; Szleifer, I., E-mail: igalsz@northwestern.edu [Department of Biomedical Engineering, Department of Chemistry, and Chemistry of Life Processes Institute, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3100 (United States)

    2014-01-14

    This work addresses the effect of the Born self-energy contribution in the modeling of the structural and thermodynamical properties of weak polyelectrolytes confined to planar and curved surfaces. The theoretical framework is based on a theory that explicitly includes the conformations, size, shape, and charge distribution of all molecular species and considers the acid-base equilibrium of the weak polyelectrolyte. Namely, the degree of charge in the polymers is not imposed but it is a local varying property that results from the minimization of the total free energy. Inclusion of the dielectric properties of the polyelectrolyte is important as the environment of a polymer layer is very different from that in the adjacent aqueous solution. The main effect of the Born energy contribution on the molecular organization of an end-grafted weak polyacid layer is uncharging the weak acid (or basic) groups and consequently decreasing the concentration of mobile ions within the layer. The magnitude of the effect increases with polymer density and, in the case of the average degree of charge, it is qualitatively equivalent to a small shift in the equilibrium constant for the acid-base equilibrium of the weak polyelectrolyte monomers. The degree of charge is established by the competition between electrostatic interactions, the polymer conformational entropy, the excluded volume interactions, the translational entropy of the counterions and the acid-base chemical equilibrium. Consideration of the Born energy introduces an additional energetic penalty to the presence of charged groups in the polyelectrolyte layer, whose effect is mitigated by down-regulating the amount of charge, i.e., by shifting the local-acid base equilibrium towards its uncharged state. Shifting of the local acid-base equilibrium and its effect on the properties of the polyelectrolyte layer, without considering the Born energy, have been theoretically predicted previously. Account of the Born energy leads

  18. Low Molecular Weight Chitosan–Insulin Polyelectrolyte Complex: Characterization and Stability Studies

    Directory of Open Access Journals (Sweden)

    Zakieh I. Al-Kurdi

    2015-03-01

    Full Text Available The aim of the work reported herein was to investigate the effect of various low molecular weight chitosans (LMWCs on the stability of insulin using USP HPLC methods. Insulin was found to be stable in a polyelectrolyte complex (PEC consisting of insulin and LMWC in the presence of a Tris-buffer at pH 6.5. In the presence of LMWC, the stability of insulin increased with decreasing molecular weight of LMWC; 13 kDa LMWC was the most efficient molecular weight for enhancing the physical and chemical stability of insulin. Solubilization of insulin-LMWC polyelectrolyte complex (I-LMWC PEC in a reverse micelle (RM system, administered to diabetic rats, results in an oral delivery system for insulin with acceptable bioactivity.

  19. Mechanical Reinforcement of Wool Fiber through Polyelectrolyte Complexation with Chitosan and Gellan Gum

    OpenAIRE

    Khairul Anuar Mat Amin; Marc in het Panhuis

    2013-01-01

    The formation of polyelectrolyte complex (PEC) wool fibers formed by dipping chitosan or gellan gum-treated wool fibers into biopolymer solutions of opposite charge is reported. Treating wool fibers with chitosan (CH) and gellan gum (GG) solutions containing food dyes resulted in improved mechanical characteristics compared to wool fibers. In contrast, pH modification of the solutions resulted in the opposite effect. The mechanical characteristics of PEC-treated fibers were affected by the or...

  20. Development of a robust pH-sensitive polyelectrolyte ionomer complex for anticancer nanocarriers

    Directory of Open Access Journals (Sweden)

    Lim CM

    2016-02-01

    Full Text Available Chaemin Lim,1,* Yu Seok Youn,2,* Kyung Soo Lee,1 Ngoc Ha Hoang,1 Taehoon Sim,1 Eun Seong Lee,3 Kyung Taek Oh1 1Department of Pharmaceutical Sciences, College of Pharmacy, Chung-Ang University, Seoul, 2Department of Pharmaceutical Sciences, School of Pharmacy, Sungkyunkwan University, Suwon, 3Division of Biotechnology, The Catholic University of Korea, Gyeonggi-do, South Korea *These authors contributed equally to this work Abstract: A polyelectrolyte ionomer complex (PIC composed of cationic and anionic polymers was developed for nanomedical applications. Here, a poly(ethylene glycol–poly(lactic acid–poly(ethylene imine triblock copolymer (PEG–PLA–PEI and a poly(aspartic acid (P[Asp] homopolymer were synthesized. These polyelectrolytes formed stable aggregates through electrostatic interactions between the cationic PEI and the anionic P(Asp blocks. In particular, the addition of a hydrophobic PLA and a hydrophilic PEG to triblock copolyelectrolytes provided colloidal aggregation stability by forming a tight hydrophobic core and steric hindrance on the surface of PIC, respectively. The PIC showed different particle sizes and zeta potentials depending on the ratio of cationic PEI and anionic P(Asp blocks (C/A ratio. The doxorubicin (dox-loaded PIC, prepared with a C/A ratio of 8, demonstrated pH-dependent behavior by the deprotonation/protonation of polyelectrolyte blocks. The drug release and the cytotoxicity of the dox-loaded PIC (C/A ratio: 8 increased under acidic conditions compared with physiological pH, due to the destabilization of the formation of the electrostatic core. In vivo animal imaging revealed that the prepared PIC accumulated at the targeted tumor site for 24 hours. Therefore, the prepared pH-sensitive PIC could have considerable potential as a nanomedicinal platform for anticancer therapy. Keywords: polyelectrolyte ionomer complex, PEG–PLA–PEI, nanomedicine, pH-sensitive, animal imaging

  1. Development of a robust pH-sensitive polyelectrolyte ionomer complex for anticancer nanocarriers.

    Science.gov (United States)

    Lim, Chaemin; Youn, Yu Seok; Lee, Kyung Soo; Hoang, Ngoc Ha; Sim, Taehoon; Lee, Eun Seong; Oh, Kyung Taek

    2016-01-01

    A polyelectrolyte ionomer complex (PIC) composed of cationic and anionic polymers was developed for nanomedical applications. Here, a poly(ethylene glycol)-poly(lactic acid)-poly(ethylene imine) triblock copolymer (PEG-PLA-PEI) and a poly(aspartic acid) (P[Asp]) homopolymer were synthesized. These polyelectrolytes formed stable aggregates through electrostatic interactions between the cationic PEI and the anionic P(Asp) blocks. In particular, the addition of a hydrophobic PLA and a hydrophilic PEG to triblock copolyelectrolytes provided colloidal aggregation stability by forming a tight hydrophobic core and steric hindrance on the surface of PIC, respectively. The PIC showed different particle sizes and zeta potentials depending on the ratio of cationic PEI and anionic P(Asp) blocks (C/A ratio). The doxorubicin (dox)-loaded PIC, prepared with a C/A ratio of 8, demonstrated pH-dependent behavior by the deprotonation/protonation of polyelectrolyte blocks. The drug release and the cytotoxicity of the dox-loaded PIC (C/A ratio: 8) increased under acidic conditions compared with physiological pH, due to the destabilization of the formation of the electrostatic core. In vivo animal imaging revealed that the prepared PIC accumulated at the targeted tumor site for 24 hours. Therefore, the prepared pH-sensitive PIC could have considerable potential as a nanomedicinal platform for anticancer therapy. PMID:26955270

  2. Development of a robust pH-sensitive polyelectrolyte ionomer complex for anticancer nanocarriers

    Science.gov (United States)

    Lim, Chaemin; Youn, Yu Seok; Lee, Kyung Soo; Hoang, Ngoc Ha; Sim, Taehoon; Lee, Eun Seong; Oh, Kyung Taek

    2016-01-01

    A polyelectrolyte ionomer complex (PIC) composed of cationic and anionic polymers was developed for nanomedical applications. Here, a poly(ethylene glycol)–poly(lactic acid)–poly(ethylene imine) triblock copolymer (PEG–PLA–PEI) and a poly(aspartic acid) (P[Asp]) homopolymer were synthesized. These polyelectrolytes formed stable aggregates through electrostatic interactions between the cationic PEI and the anionic P(Asp) blocks. In particular, the addition of a hydrophobic PLA and a hydrophilic PEG to triblock copolyelectrolytes provided colloidal aggregation stability by forming a tight hydrophobic core and steric hindrance on the surface of PIC, respectively. The PIC showed different particle sizes and zeta potentials depending on the ratio of cationic PEI and anionic P(Asp) blocks (C/A ratio). The doxorubicin (dox)-loaded PIC, prepared with a C/A ratio of 8, demonstrated pH-dependent behavior by the deprotonation/protonation of polyelectrolyte blocks. The drug release and the cytotoxicity of the dox-loaded PIC (C/A ratio: 8) increased under acidic conditions compared with physiological pH, due to the destabilization of the formation of the electrostatic core. In vivo animal imaging revealed that the prepared PIC accumulated at the targeted tumor site for 24 hours. Therefore, the prepared pH-sensitive PIC could have considerable potential as a nanomedicinal platform for anticancer therapy. PMID:26955270

  3. Fluorescence array-based sensing of nitroaromatics using conjugated polyelectrolytes.

    Science.gov (United States)

    Wu, Jiatao; Tan, Chunyan; Chen, Zhifang; Chen, Yu Zong; Tan, Ying; Jiang, Yuyang

    2016-05-23

    A sensor array consisting of six cationic fluorescent conjugated polyelectrolytes (CPEs) is reported, which could readily differentiate between nine closely related hydrophilic nitroaromatics (NACs) in separate aqueous solutions by fluorescence pattern recognition and linear discrimination analysis (LDA). PMID:27169808

  4. Formation of intra- and interparticle polyelectrolyte complexes between cationic nanogel and strong polyanion.

    Science.gov (United States)

    Ogawa, Kazuyoshi; Sato, Seigo; Kokufuta, Etsuo

    2005-05-24

    Polyelectrolyte complex formation of a strong polyanion, potassium poly(vinyl alcohol) sulfate (KPVS), with positively charged nanogels was studied at 25 degrees C in aqueous solutions with different KCl concentrations (C(s)) as a function of the polyion-nanogel mixing ratio based on moles of anions versus cations. Used as the gel sample was a polyampholytic nanogel consisting of lightly cross-linked terpolymer chains of N-isopropylacrylamide, acrylic acid, and 1-vinylimidazole; thus, the complexation was performed at pH 3 at which the imidazole groups are fully protonated to generate positive charges. Turbidimetric titration was employed to vary the mixing ratio. Also employed for studies of the resulting complexes at different stages of the titration were dynamic light scattering (DLS) and static light scattering (SLS) techniques. It was found from the titration as well as DLS and SLS that there is a critical mixing ratio (cmr) at which both the size and molar mass of the complexed gel particles abruptly increase. The value of the cmr at C(s) = 0 or 0.01 M (mol/L) was observed at approximately 1:1 mixing ratio of anions versus cations but at lower mixing ratios than the 1:1 ratio under conditions of C(s) = 0.05 and 0.1 M. At the mixing ratios less than the cmr, the molar mass of the complex agrees with that of one gel particle with the calculated amount of the bound KPVS ions, indicating the formation of an "intraparticle" KPVS-nanogel complex, by the aggregation of which an "interparticle" complex is formed at the cmr. During the process of the intraparticle complex formation, both the hydrodynamic radius by DLS and the radius gyration by SLS decreased with increasing mixing ratio, demonstrating the gel collapse due to the complexation. At C(s) = 0 or 0.01 M and under conditions where the amount of KPVS bindings was less than half of the nanogel cations, however, the decrease of the hydrodynamic radius was very small, while the radius gyration fell monotonically

  5. Effects of conformational ordering on protein/polyelectrolyte electrostatic complexation: ionic binding and chain stiffening

    Science.gov (United States)

    Cao, Yiping; Fang, Yapeng; Nishinari, Katsuyoshi; Phillips, Glyn O.

    2016-01-01

    Coupling of electrostatic complexation with conformational transition is rather general in protein/polyelectrolyte interaction and has important implications in many biological processes and practical applications. This work studied the electrostatic complexation between κ-carrageenan (κ-car) and type B gelatin, and analyzed the effects of the conformational ordering of κ-car induced upon cooling in the presence of potassium chloride (KCl) or tetramethylammonium iodide (Me4NI). Experimental results showed that the effects of conformational ordering on protein/polyelectrolyte electrostatic complexation can be decomposed into ionic binding and chain stiffening. At the initial stage of conformational ordering, electrostatic complexation can be either suppressed or enhanced due to the ionic bindings of K+ and I− ions, which significantly alter the charge density of κ-car or occupy the binding sites of gelatin. Beyond a certain stage of conformational ordering, i.e., helix content θ > 0.30, the effect of chain stiffening, accompanied with a rapid increase in helix length ζ, becomes dominant and tends to dissociate the electrostatic complexation. The effect of chain stiffening can be theoretically interpreted in terms of double helix association. PMID:27030165

  6. Effect of polyelectrolyte-surfactant complexation on Marangoni transport at a liquid-liquid interface.

    Science.gov (United States)

    Dunér, Gunnar; Kim, Michelle; Tilton, Robert D; Garoff, Stephen; Przybycien, Todd M

    2016-04-01

    Complexation of surfactants and oppositely charged polyelectrolytes is expected to alter Marangoni transport at a fluid interface compared to either single component system due to altered interfacial tension isotherms and mass transfer rates as well as adsorption irreversibility effects. We investigate Marangoni transport at the oil/water interface by passing mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) and cationic polyelectrolyte poly(3-(2-methylpropionamide)propyl) trimethylammonium chloride-acrylamide (poly[AM-MAPTAC]), or rinsing solutions, over an oil/water interface in a radial, stagnation point flow. The displacements of adsorbed tracer particles are recorded through optical microscopy. The net displacement, defined as the sum of the displacements occurring during the adsorption and desorption stages of one application and rinsing cycle, is up to 10 times greater for complexing surfactant/polymer mixtures compared to either single component system. The enhanced net displacement is largely determined by the enhanced transport upon adsorption, while the reverse displacement that would normally occur upon rinsing is partially suppressed by partially irreversible polymer adsorption at the oil/water interface. In addition to effects of complexation on interfacial tension gradient induced flow, complexation effects on the bulk, and possibly interfacial, viscosity also influence the interfacial transport. PMID:26775240

  7. Temperature induced complex formation-deformation behavior of collagen model peptides and polyelectrolytes in aqueous solution

    OpenAIRE

    Terao, Ken; Kanenaga, Ryoko; Yoshida, Tasuku; Mizuno, Kazunori; Bächinger, Hans Peter

    2015-01-01

    Since the triple-helical collagen model peptides with a free N-terminus have three cationic groups at one end, it may have strong interactions with polyelectrolytes. In this study, complex formation behavior was investigated for sodium carboxymethyl amylose (NaCMA) + H-(Pro-Pro-Gly)10-OH (PPG10), a collagen model peptide, in aqueous NaCl with ionic strength of 10 mM and 100 mM by means of small-angle X-ray scattering (SAXS) and circular dichroism at different temperatures. The previously repo...

  8. Induced Crystallization of Polyelectrolyte-Surfactant Complexes at the Gas-Water Interface

    OpenAIRE

    Vaknin, D; Dahlke, S.; Travesset, A.; Nizri, G.; Magdassi, S.

    2004-01-01

    Synchrotron-X-ray and surface tension studies of a strong polyelectrolyte (PE) in the semi-dilute regime (~ 0.1M monomer-charges) with varying surfactant concentrations show that minute surfactant concentrations induce the formation of a PE-surfactant complex at the gas/solution interface. X-ray reflectivity and grazing angle X-ray diffraction (GIXD) provide detailed information of the top most layer, where it is found that the surfactant forms a two-dimensional liquid-like monolayer, with a ...

  9. Mechanical Reinforcement of Wool Fiber through Polyelectrolyte Complexation with Chitosan and Gellan Gum

    Directory of Open Access Journals (Sweden)

    Khairul Anuar Mat Amin

    2013-10-01

    Full Text Available The formation of polyelectrolyte complex (PEC wool fibers formed by dipping chitosan or gellan gum-treated wool fibers into biopolymer solutions of opposite charge is reported. Treating wool fibers with chitosan (CH and gellan gum (GG solutions containing food dyes resulted in improved mechanical characteristics compared to wool fibers. In contrast, pH modification of the solutions resulted in the opposite effect. The mechanical characteristics of PEC-treated fibers were affected by the order of addition, i.e., dipping GG-treated fibers into chitosan resulted in mechanical reinforcement, whereas the reverse-order process did not.

  10. Molecular Weight and Charge Density Asymmetry in Polyelectrolyte Complexation

    Science.gov (United States)

    Audus, Debra; Fredrickson, Glenn; Duechs, Dominik

    2009-03-01

    We investigate the phase diagram of oppositely charged polymers in a good solvent using a field-theoretic model. Mean-field solutions fail to predict the experimentally observed macroscopic phase separation into a solvent-rich phase and a dense liquid aggregate of polymers - a ``complex coacervate.'' We therefore study the model within a one-loop approximation, which accounts for Gaussian fluctuations in electrostatic and chemical potentials. Our particular focus is the effect of molecular weight, ionic strength, and charge asymmetry on the phase envelope. A set of dimensionless parameters is identified that dictate the size and shape of the two-phase region. Our results should be helpful in guiding experimental studies of coacervation.

  11. Coarse-grained simulations of polyelectrolyte complexes: MARTINI models for poly(styrene sulfonate) and poly(diallyldimethylammonium)

    Science.gov (United States)

    Vögele, Martin; Holm, Christian; Smiatek, Jens

    2015-12-01

    We present simulations of aqueous polyelectrolyte complexes with new MARTINI models for the charged polymers poly(styrene sulfonate) and poly(diallyldimethylammonium). Our coarse-grained polyelectrolyte models allow us to study large length and long time scales with regard to chemical details and thermodynamic properties. The results are compared to the outcomes of previous atomistic molecular dynamics simulations and verify that electrostatic properties are reproduced by our MARTINI coarse-grained approach with reasonable accuracy. Structural similarity between the atomistic and the coarse-grained results is indicated by a comparison between the pair radial distribution functions and the cumulative number of surrounding particles. Our coarse-grained models are able to quantitatively reproduce previous findings like the correct charge compensation mechanism and a reduced dielectric constant of water. These results can be interpreted as the underlying reason for the stability of polyelectrolyte multilayers and complexes and validate the robustness of the proposed models.

  12. Coarse-grained simulations of polyelectrolyte complexes: MARTINI models for poly(styrene sulfonate) and poly(diallyldimethylammonium)

    Energy Technology Data Exchange (ETDEWEB)

    Vögele, Martin [Institute for Computational Physics, University of Stuttgart, Stuttgart (Germany); Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt a. M. (Germany); Holm, Christian; Smiatek, Jens, E-mail: smiatek@icp.uni-stuttgart.de [Institute for Computational Physics, University of Stuttgart, Stuttgart (Germany)

    2015-12-28

    We present simulations of aqueous polyelectrolyte complexes with new MARTINI models for the charged polymers poly(styrene sulfonate) and poly(diallyldimethylammonium). Our coarse-grained polyelectrolyte models allow us to study large length and long time scales with regard to chemical details and thermodynamic properties. The results are compared to the outcomes of previous atomistic molecular dynamics simulations and verify that electrostatic properties are reproduced by our MARTINI coarse-grained approach with reasonable accuracy. Structural similarity between the atomistic and the coarse-grained results is indicated by a comparison between the pair radial distribution functions and the cumulative number of surrounding particles. Our coarse-grained models are able to quantitatively reproduce previous findings like the correct charge compensation mechanism and a reduced dielectric constant of water. These results can be interpreted as the underlying reason for the stability of polyelectrolyte multilayers and complexes and validate the robustness of the proposed models.

  13. Tuning nanoscale viscoelasticity of polyelectrolyte complexes with multiple types of cross-links

    Science.gov (United States)

    Ma, Tianzhu; Han, Biao; Lee, Daeyeon; Han, Lin

    Mechanical properties of hydrogels are manifestation of cross-link type and density, fixed charges and water-polymer interactions. In this study, we revealed how different types of cross-links regulate the nanoscale viscoelasticity of polyelectrolyte networks. Ionically cross-linked PAH/PAA layer-by-layer complexes were modified to include covalent cross-links using EDC. AFM-nanoindentation and force relaxation were performed at various ionic strength (0.01-1M) and pH (1.5-5.5). As-assembled networks, held only by ionic cross-links, underwent >95% relaxation, dominated by cross-link breaking and re-formation. Addition of covalent cross-links increased the instantaneous modulus by 1.6-fold and attenuated relaxation to ~80% of net neutral states (pH >=3.5), as covalent cross-links provide additional elastic components. The network remained stabilized when all ionic cross-links were dissociated at pH poroelasticity. Taken together, this study demonstrates the potential of using multiple cross-linking types to tune the viscoelastic mechanisms in polyelectrolyte complexes.

  14. Needlelike and spherical polyelectrolyte complex nanoparticles of poly(l-lysine) and copolymers of maleic acid.

    Science.gov (United States)

    Müller, M; Reihs, T; Ouyang, W

    2005-01-01

    We report on the bulk and surface properties of dispersions consisting of nonstoichiometric polyelectrolyte complex (PEC) nanoparticles. PEC nanoparticles were prepared by mixing poly(l-lysine) (PLL) or poly(diallyldimethylammonium chloride) (PDADMAC) with poly(maleic acid-co-alpha-methylstyrene) (PMA-MS) or poly(maleic acid-co-propylene) (PMA-P). The monomolar mixing ratio was n-/n+ = 0.6, and the concentration ranged from 1 to 6 mmol/L. Subsequent centrifugation enabled the separation of the excess polycation, resulting in a stable coacervate phase further used in the experiments. The bulk phase parameters turbidity and hydrodynamic radius (R(h)) of the PEC nanoparticles showed a linear dependence on the total polymer content independently of the mixed polyelectrolytes. This can be interpreted by the increased collision probability of the polyelectrolyte chains when the overlap concentration is approached or exceeded. Different morphologies of the cationic PEC nanoparticles, which were solution-cast onto Si supports, were obtained by atomic force microscopy (AFM). The combinations of PLL/PMA-MS and PDADMAC/PMA-MS revealed more or less hemispherical particle shapes, whereas that of PLL/PMA-P revealed an elongated needlelike particle shape. Circular dichroism and attenuated total reflection Fourier transform infrared (ATR-FTIR) measurements proved the alpha-helical conformation for the PEC PLL/PMA-P and the random coil conformation for the PEC PLL/PMA-MS. We conclude that stiff alpha-helical PLL induces anisotropic elongated PEC nanoparticles, whereas randomly coiled PLL forms isotropic spherical PEC nanoparticles. PMID:15620340

  15. New polyelectrolyte complex from pectin/chitosan and montmorillonite clay.

    Science.gov (United States)

    da Costa, Marcia Parente Melo; de Mello Ferreira, Ivana Lourenço; de Macedo Cruz, Mauricio Tavares

    2016-08-01

    A new nanocomposite hydrogel was prepared by forming a crosslinked hybrid polymer network based on chitosan and pectin in the presence of montmorillonite clay. The influence of clay concentration (0.5 and 2% wt) as well as polymer ratios (1:1, 1:2 and 2:1) was investigated carefully. The samples were characterized by different techniques: transmission and scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, swelling degree and compression test. Most samples presented swelling degree above 1000%, which permits characterizing them as superabsorbent material. Images obtained by transmission electron microscopy showed the presence of clay nanoparticles into hydrogel. The hydrogels' morphological properties were evaluated by scanning electron microscope in high and low-vacuum. The micrographs showed that the samples presented porous. The incorporation of clay produced hydrogels with differentiated morphology. Thermogravimetric analysis results revealed that the incorporation of clay in the samples provided greater thermal stability to the hydrogels. The compression resistance also increased with addition of clay.

  16. New polyelectrolyte complex from pectin/chitosan and montmorillonite clay.

    Science.gov (United States)

    da Costa, Marcia Parente Melo; de Mello Ferreira, Ivana Lourenço; de Macedo Cruz, Mauricio Tavares

    2016-08-01

    A new nanocomposite hydrogel was prepared by forming a crosslinked hybrid polymer network based on chitosan and pectin in the presence of montmorillonite clay. The influence of clay concentration (0.5 and 2% wt) as well as polymer ratios (1:1, 1:2 and 2:1) was investigated carefully. The samples were characterized by different techniques: transmission and scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, swelling degree and compression test. Most samples presented swelling degree above 1000%, which permits characterizing them as superabsorbent material. Images obtained by transmission electron microscopy showed the presence of clay nanoparticles into hydrogel. The hydrogels' morphological properties were evaluated by scanning electron microscope in high and low-vacuum. The micrographs showed that the samples presented porous. The incorporation of clay produced hydrogels with differentiated morphology. Thermogravimetric analysis results revealed that the incorporation of clay in the samples provided greater thermal stability to the hydrogels. The compression resistance also increased with addition of clay. PMID:27112858

  17. Synthesis, self-assembly and photoinduced surface-relief gratings of a polyacrylate-based Azo polyelectrolyte

    Science.gov (United States)

    He, Yaning; Wang, Haopeng; Tuo, Xinlin; Deng, Wei; Wang, Xiaogong

    2004-06-01

    A polyacrylate-based azo polyelectrolyte was synthesized and characterized by the spectroscopic methods and thermal analysis. Layer-by-layer self-assembly of the azo polyelectrolyte through electrostatic adsorption was explored. By using a dipping solution of the anionic azo polyelectrolyte in anhydrous DMF, together with an aqueous solution of cationic poly(diallyldimethylammonium chloride) (PDAC), high quality multilayer films were obtained through the sequential deposition of the oppositely charged polyelectrolytes. With interfering illumination of Ar + laser beams (488 nm), significant surface-relief gratings formed on the self-assembled multiplayer films were observed.

  18. Ionizing radiation in the polyelectrolytes technology

    International Nuclear Information System (INIS)

    Gamma ray and accelerated electron beam application in the chemistry of polyelectrolytes is presented. The polyelectrolytes preparation is based on radiation induced polymerization of aqueous solutions containing an appropriate mixture of monomers such as acrylamide, acrylic acid, vinyl acetate, diallyldimethylammonium chloride and certain initiators, complexing agents and chain transfer agents. The effects of absorbed dose, rate of absorbed dose and chemical composition of aqueous solution on the polymerization process are discussed. The results obtained by testing these polyelectrolytes with waste water from food industry are also given. (author)

  19. Polyelectrolyte complexes via desalting mixtures of hyaluronic acid and chitosan-Physicochemical study and structural analysis.

    Science.gov (United States)

    Lalevée, G; Sudre, G; Montembault, A; Meadows, J; Malaise, S; Crépet, A; David, L; Delair, T

    2016-12-10

    Polyelectrolyte complexes (PECs) were prepared from Chitosan (CS) and Hyaluronic Acid (HYA) homogeneous mixtures of aqueous solutions. The method consisted of preparing a homogeneous mixture of the two polysaccharides via charge screening at high salt concentrations. Then, the mixture was dialyzed, leading to the controlled self-assembly of the two polyelectrolytes. Critical parameters like the chitosan degree of acetylation (DA) and molar mass (Mw), the residual salt concentration and the molar charge ratio r=nNH3(+) (CS)/nCOO(-) (HYA) accounted for the transition from homogeneous aqueous solutions to colloidal suspensions (r=0.1) or gel coacervates (r=0.5). The influence of the DA and Mw of CS was evaluated by visual observations, light scattering and rheological measurements. For low values of r, Small Angle X-ray Scattering (SAXS) experiments revealed that the HYA nanostructure was weakly affected by the presence of PECs. On the contrary, the structure was impacted when increasing r, revealing a heterogeneous aggregate morphology with ladder-like chain interactions. PMID:27577900

  20. Bathroom greywater recycling using polyelectrolyte-complex bilayer membrane: Advanced study of membrane structure and treatment efficiency.

    Science.gov (United States)

    Oh, K S; Poh, P E; Chong, M N; Chan, E S; Lau, E V; Saint, C P

    2016-09-01

    Polyelectrolyte-complex bilayer membrane (PCBM) was fabricated using biodegradable chitosan and alginate polymers for subsequent application in the treatment of bathroom greywater. In this study, the properties of PCBMs were studied and it was found that the formation of polyelectrolyte network reduced the molecular weight cut-off (MWCO) from 242kDa in chitosan membrane to 2.71kDa in PCBM. The decrease in MWCO of PCBM results in better greywater treatment efficiency, subsequently demonstrated in a greywater filtration study where treated greywater effluent met the household reclaimed water standard of material in producing clean treated greywater for non-potable applications. PMID:27185127

  1. Chitosan-Based Zwitterionic Polyelectrolytes and Their N-Phosphobetainates: Facile Synthesis and Aqueous Solution Behaviors

    Institute of Scientific and Technical Information of China (English)

    Hongmei Kang; Yuanli Cai; Haijia Zhang; Junjie Deng; Pengsheng Liu

    2005-01-01

    @@ 1Introduction Chitosan has remarkable potential applications in pharmaceutical and cosmetic formulations[1], e.g. for drug delivery systems, tissue engineering, transplant and cell regeneration due to its excellent biocompatibility, biodegradability, mucoadhesion, etc. Its major drawback as considered for pharmaceutical and cosmetic formulations is its poor solubility due to strong hydrogen bonding and compact structures. Considerable efforts were focused on improving its solubility and enforcing its functionality[1]. As well-known that phosphorylcholine (PC), the structural component of cell membrane, is an amphiphile containing the zwitterionic quaternary ammonium and phosphonic acid moieties (phosphobetaine groups). There has been an intensive effort over the past decades to prepare and explore potential applications of the synthetic PC-polymers[2].In this paper, we describe a facile synthesis of chitosan derivatives containing zwitterionic secondary/tertiary amine and phosphonic acid groups and their further N-phosphobetainates. The polyelectrolyte effect and anti-polyelectrolyte effect of the chitosan-based zwitterionic polyelectrolytes were studied.

  2. Electrostatics of Rigid Polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Wong, G.C.L.

    2009-06-04

    The organization of rigid biological polyelectrolytes by multivalent ions and macroions are important for many fundamental problems in biology and biomedicine, such as cytoskeletal regulation and antimicrobial sequestration in cystic fibrosis. These polyelectrolytes have been used as model systems for understanding electrostatics in complex fluids. Here, we review some recent results in theory, simulations, and experiments.

  3. Synergistic strengthening of polyelectrolyte complex membranes by functionalized carbon nanotubes and metal ions.

    Science.gov (United States)

    Liu, Tao; An, Quan-Fu; Zhao, Qiang; Wu, Jia-Kai; Song, Yi-Hu; Zhu, Bao-Ku; Gao, Cong-Jie

    2015-01-01

    Hydrophilic polymers have garnered much attention due to their critical roles in various applications such as molecular separation membranes, bio-interfaces, and surface engineering. However, a long-standing problem is that their mechanical properties usually deteriorate at high relative humidity (RH). Through the simultaneous incorporation of functionalized carbon nanotubes and copper ions (Cu(2+)), this study introduces a facile method to fabricate high strength polyelectrolyte complex nanohybrid membranes resistant to high RH (90%). For example, the tensile strength of the nanohybrid membranes is 55 MPa at 90% RH (80% of the original value at 30% RH). These results are explained by copper ions depressing the swelling degree of the membrane, and functionalized carbon nanotubes promoting stress transfer between the polymer matrix and them. The nanohybrid membranes are efficient in separating water/alcohol mixtures containing relatively high water content (up to 30 wt%), whereas common hydrophilic polymer membranes usually suffer from excessive swelling under this condition. PMID:25586650

  4. Auricularia auricular polysaccharide-low molecular weight chitosan polyelectrolyte complex nanoparticles: Preparation and characterization

    Directory of Open Access Journals (Sweden)

    Wei Xiong

    2016-06-01

    Full Text Available Novel polyelectrolyte complex nanoparticles (AAP/LCS NPs were prepared in this study and these were produced by mixing negatively charged auricularia auricular polysaccharide (AAP with positively charged low molecular weight chitosan (LCS in an aqueous medium. The AAP was extracted and purified from auricularia auricular, and then characterized by micrOTOF-Q mass spectrometry, UV/Vis spectrophotometry, moisture analyzer and SEM. The yield, moisture, and total sugar content of the AAP were 4.5%, 6.2% and 90.12% (w/w, respectively. The AAP sample was water-soluble and exhibited white flocculence. The characteristics of AAP/LCS NPs, such as the particle size, zeta potential, morphology, FT-IR spectra, DSC were investigated. The results obtained revealed that the AAP/LCS NPs had a spherical shape with a diameter of 223 nm and a smooth surface, and the results of the FT-IR spectra and DSC investigations indicated that there was an electrostatic interaction between the two polyelectrolyte polymers. Bovine serum albumin (BSA, pI = 4.8 and bovine hemoglobin (BHb, pI = 6.8 were used as model drugs to investigate the loading and release features of the AAP/LCS NPs. The results obtained showed that the AAP/LCS NPs had a higher entrapment efficiency (92.6% for BHb than for BSA (81.5%. The cumulative release of BSA and BHb from AAP/LCS NPs after 24 h in vitro was 95.4% and 91.9%, respectively. The in vitro release demonstrated that AAP/LCS NPs provided a sustained release matrix suitable for the delivery of protein drugs. These studies demonstrate that AAP/LCS NPs have a very promising potential as a delivery system for protein drugs.

  5. Preparation of polyelectrolyte complex nanoparticles of chitosan and poly(2-acry1amido-2-methylpropanesulfonic acid) for doxorubicin release.

    Science.gov (United States)

    Zhang, Liping; Wang, Jie; Ni, Caihua; Zhang, Yanan; Shi, Gang

    2016-01-01

    A new kind of polyelectrolyte complex (PEC) based on cationic chitosan (CS) and anionic poly(2-acry1amido-2-methylpropanesulfonic acid) (PAMPS) was prepared using a polymer-monomer pair reaction system. Chitosan was mixed with 2-acry1amido-2-methylpropanesulfonic acid) (AMPS) in an aqueous solution, followed by polymerization of AMPS. The complex was formed by electrostatic interaction of NH3(+) groups of CS and SO3(-) groups of AMPS, leading to a formation of complex nanoparticles of CS-PAMPS. A series of nanoparticles were obtained by changing the weight ratio of CS to AMPS, the structure and properties of nanoparticles were investigated. It was observed that the nanoparticles possessed spherical morphologies with average diameters from 255 nm to 390 nm varied with compositions of the nanoparticles. The nanoparticles were used as drug vehicles for doxorubicin, displaying relative high drug loading rate and encapsulation rate. The vitro release profiles revealed that the drug release could be controlled by adjusting pH of the release media. The nanoparticles demonstrated apparent advantages such as simple preparation process, free of organic solvents, size controllable, good biodegradability and biocompatibility, and they could be potentially used in drug controlled release field.

  6. On the effect of temperature on the reentrant condensation in polyelectrolyte-liposome complexation

    OpenAIRE

    Sennato, S.; Truzzolillo, D.; Bordi, F.; Cametti, C.

    2008-01-01

    In systems of highly charged linear polyelectrolytes and oppositely charged colloidal particles, long-lived clusters of polyelectrolyte-decorated particles form in an interval of concentrations around the isoelectric point, where reentrant condensation connected to charge inversion of cluster is observed. The mechanisms that drive the aggregation and stabilize, at the different polymer/particle ratios, a well defined size of the aggregates are not completely understood. Moreover, a central qu...

  7. Hybrid inorganic-organic nano- and microcomposites based on silica sols and synthetic polyelectrolytes

    Directory of Open Access Journals (Sweden)

    2008-02-01

    Full Text Available Interaction between anionic (and cationic colloidal particles of silica having the particles diameters 12 and 22 nm with synthetic cationic (and anionic polyelectrolytes of various nature and structure was studied by potentiometric, conductimetric spectroturbidimetric and viscometric methods in aqueous solution. It was shown that the complexation of silica nanoparticles with linear polyelectrolytes leads to formation of mostly stoichiometric interpolyelectrolyte complexes (IPEC which precipitate from aqueous solution. Casting of water-soluble IPEC followed by thermal treatment gives thin composite films insoluble in water while ‘layer by layer’ (LbL deposition of polyelectrolyte components onto silica sols leads to formation of multilayered nano- and microcomposites. The possible mechanism of formation of LbL multilayers consisting of silica sol (SiO2 ‘cores’ and polyethyeleneimine-polyacrylic acid (PEI-PAA ‘shells’ was suggested. It was found that in diluted aqueous solution the radius of gyration, Rg and hydrodynamic radius, Rhmean of LbL particles are independent on LbL concentration and smaller than 100 nm. The zeta potential values of LbL particles are arranged between –10 and –30 mV. The average size of LbL particles estimated by scanning electron microscopy (SEM is in the range of 200–500 nm. Thermal treatment of LbL multilayers followed by etching of (SiO2 ‘core’ by HF leads to formation of a series of spherical nanocavities and blob-like microcavities.

  8. A two-step process for controlling the surface smoothness of polyelectrolyte-based microcapsules.

    Science.gov (United States)

    Lacík, I; Anilkumar, A V; Wang, T G

    2001-01-01

    Biocompatibility is one of the crucial requirements to be fulfilled when designing devices for immunoisolation of transplanted cells. The quality of the capsule surface (smoothness/roughness) influences the nature of cell overgrowth on it by immunocytes, which eventually may lead to the transplant failure. A microcapsule has been developed based on the polyelectrolyte complexation of the polyanions sodium alginate and cellulose sulphate with the polycation poly(methylene-co-guanidine), which was successfully tested in rodent animal models. Recently, the principles for controlling the surface smoothness of these capsules has been identified. This paper reports on a two-step process used for production of stable capsules with improved surface properties. The methodology involves separating the process of drop shape recovery and precursor capsule formation from the process of membrane formation by applying a two-reactor design. The multi-loop reactors are connected in series, and the process separation is given by the different composition of cation solutions flowing in each reactor. This process enables one to prepare the microcapsule immunoisolation device, which can differ in the extent of surface roughness and, thus, is suitable for studying the effect of surface morphology of the immunoisolation device on cell overgrowth. The effect of this process on the capsule permeability has also been evaluated.

  9. Continuous testing system for Baeyer-Villiger biooxidation using recombinant Escherichia coli expressing cyclohexanone monooxygenase encapsulated in polyelectrolyte complex capsules.

    Science.gov (United States)

    Bučko, Marek; Schenkmayerová, Andrea; Gemeiner, Peter; Vikartovská, Alica; Mihovilovič, Marko D; Lacík, Igor

    2011-08-10

    An original strategy for universal laboratory testing of Baeyer-Villiger monooxygenases based on continuous packed-bed minireactor connected with flow calorimeter and integrated with bubble-free oxygenation is reported. Model enantioselective Baeyer-Villiger biooxidations of rac-bicyclo[3.2.0]hept-2-en-6-one to corresponding lactones (1R,5S)-3-oxabicyclo-[3.3.0]oct-6-en-3-one and (1S,5R)-2-oxabicyclo-[3.3.0]oct-6-en-3-one as important chiral synthons for the synthesis of bioactive compounds were performed in the minireactor equipped with a column packed with encapsulated recombinant cells Escherichia coli overexpressing cyclohexanone monooxygenase. The cells were encapsulated in polyelectrolyte complex capsules formed by reaction of oppositely charged polymers utilizing highly reproducible and controlled encapsulation process. Encapsulated cells tested in minireactor exhibited high operational stability with 4 complete substrate conversions to products and 6 conversions above 80% within 14 repeated consecutive biooxidation tests. Moreover, encapsulated cells showed high enzyme stability during 91 days of storage with substrate conversions above 80% up to 60 days of storage. Furthermore, usable thermometric signal of Baeyer-Villiger biooxidation obtained by flow calorimetry using encapsulated cells was utilized for preparatory kinetic study in order to guarantee sub-inhibitory initial substrate concentration for biooxidation tests.

  10. Larger red-shift in optical emissions obtained from the thin films of globular proteins (BSA, lysozyme) - polyelectrolyte (PAA) complexes

    Science.gov (United States)

    Talukdar, Hrishikesh; Kundu, Sarathi; Basu, Saibal

    2016-09-01

    Globular proteins (lysozyme and BSA) and polyelectrolyte (sodium polyacrylic acid) are used to form protein-polyelectrolyte complexes (PPC). Out-of-plane structures of ≈30-60 nm thick PPC films and their surface morphologies have been studied by using X-ray reflectivity and atomic force microscopy, whereas optical behaviors of PPC and protein conformations have been studied by using UV-vis, photoluminescence and FTIR spectroscopy respectively. Our study reveals that thin films of PPC show a larger red-shift of 23 and 16 nm in the optical emissions in comparison to that of pure protein whereas bulk PPC show a small blue-shift of ≈3 nm. A small amount of peak-shift is found to occur due to the heat treatment or concentration variation of the polyelectrolyte/protein in bulk solution but cannot produce such film thickness independent larger red-shift. Position of the emission peak remains nearly unchanged with the film thickness. Mechanism for such larger red-shift has been proposed.

  11. Formation of nano-hydroxyapatite crystal in situ in chitosan-pectin polyelectrolyte complex network

    International Nuclear Information System (INIS)

    Hydroxyapatite (HA)/polysaccharide composites have been widely used in bone tissue engineering due to their chemical similarity to natural bone. Polymer matrix-mediated synthesis of nano-hydroxyapatite is one of the simplest models for biomimetic. In this article, the nano-hydroxyapatite/chitosan-pectin (nHCP) composites were prepared through in situ mineralization of hydroxyapatite in chitosan-pectin polyelectrolyte complex (PEC) network. The formation processes of nHCP were investigated by X-ray diffraction (XRD) analysis. The interactions between nHA crystal and chitosan-pectin PEC networks were studied using Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The morphology and structure of nHA crystal were characterized by XRD and Transmission Electron Microscope (TEM). Results suggested that the interfacial interactions between nano-hydroxyapatite crystal and chitosan-pectin PEC network assist the site specific nucleation and growth of nHA nanoparticles. The nHA crystals grow along the c-axis. In this process, pH value is the main factor to control the nucleation and growth of nHA crystal in chitosan-pectin PEC networks, because both the interactions' strength between nHA crystal and chitosan-pectin and diffusion rate of inorganic ions depend on the pH value of the reaction system. Apart from the pH value, the chitosan/pectin ratio and [Ca2+] also take important effects on the formation of nHA crystal. An effective way to control the size of nHA crystal is to adjust the content of pectin and [Ca2+]. It is interesting that the Zeta potential of nHCP composites is about - 30 mV when the chitosan/pectin ratio ≤ 1:1, and the dispersion solution of nHCP composites has higher stability, which provides the possibility to prepare 3D porous scaffolds with nHCP for bone tissue engineering.

  12. The preparation of polyelectrolyte complexes carboxymethyl chitosan(CMC)-pectin by reflux method as a Pb (II) metal ion adsorbent

    Science.gov (United States)

    Hastuti, Budi; Mudasir, Siswanta, Dwi; Triyono

    2016-02-01

    Aim of this research is to synthesized a chemically stable polyelectrolyte complexs carboxymetyl chitosan CMC-pectin as Pb(II) ion adsorbent by reflux method. During synthesis process, the optimum mass ratio of CMC and pectin was pre-determined and the active groups of the CMC-pectin complex was characterized by using IR spectrofotometer. Finally, adsorption capacity of the adsorbent material for Pb (II) ions was studied under optimum condition, i.e. adsorbent mass, contact time, and pH. Result shows that CMC could be succesfully combined with pectin to produce CMC-pectin complex. The optimum mass ratio CMC: pectin to form the polyelectrolyte complexs CMC-pectin was 70% : 30%. The active groups identified in the CMC-pectin complex was a hydroxyl (OH) and carboxylate (-COOH) groups. The optimum conditions for Pb (II) ion absoprtion was 10 mg of the adsorbent mass, 75 min of contact time, and pH 5. This material can be effectively used as adsorbents for Pb (II) ions, where up to 91% Pb (II) metal ions was adsorbed from aqueous solution and the adsorption capacity of the adsorbent was 41.63 mg/g.

  13. Polyelectrolyte Complexes of Low Molecular Weight PEI and Citric Acid as Efficient and Nontoxic Vectors for in Vitro and in Vivo Gene Delivery.

    Science.gov (United States)

    Giron-Gonzalez, M Dolores; Salto-Gonzalez, Rafael; Lopez-Jaramillo, F Javier; Salinas-Castillo, Alfonso; Jodar-Reyes, Ana Belen; Ortega-Muñoz, Mariano; Hernandez-Mateo, Fernando; Santoyo-Gonzalez, Francisco

    2016-03-16

    Gene transfection mediated by the cationic polymer polyethylenimine (PEI) is considered a standard methodology. However, while highly branched PEIs form smaller polyplexes with DNA that exhibit high transfection efficiencies, they have significant cell toxicity. Conversely, low molecular weight PEIs (LMW-PEIs) with favorable cytotoxicity profiles display minimum transfection activities as a result of inadequate DNA complexation and protection. To solve this paradox, a novel polyelectrolyte complex was prepared by the ionic cross-linking of branched 1.8 kDa PEI with citric acid (CA). This system synergistically exploits the good cytotoxicity profile exhibited by LMW-PEI with the high transfection efficiencies shown by highly branched and high molecular weight PEIs. The polyectrolyte complex (1.8 kDa-PEI@CA) was obtained by a simple synthetic protocol based on the microwave irradiation of a solution of 1.8 kDa PEI and CA. Upon complexation with DNA, intrinsic properties of the resulting particles (size and surface charge) were measured and their ability to form stable polyplexes was determined. Compared with unmodified PEIs the new complexes behave as efficient gene vectors and showed enhanced DNA binding capability associated with facilitated intracellular DNA release and enhanced DNA protection from endonuclease degradation. In addition, while transfection values for LMW-PEIs are almost null, transfection efficiencies of the new reagent range from 2.5- to 3.8-fold to those of Lipofectamine 2000 and 25 kDa PEI in several cell lines in culture such as CHO-k1, FTO2B hepatomas, L6 myoblasts, or NRK cells, simultaneously showing a negligible toxicity. Furthermore, the 1.8 kDa-PEI@CA polyelectrolyte complexes retained the capability to transfect eukaryotic cells in the presence of serum and exhibited the capability to promote in vivo transfection in mouse (as an animal model) with an enhanced efficiency compared to 25 kDa PEI. Results support the polyelectrolyte complex

  14. A fiber-optic pH sensor based on polyelectrolyte multilayers embedded with gold nanoparticles

    Science.gov (United States)

    Tou, Z. Q.; Chan, C. C.; Leong, Stephanie

    2014-07-01

    We report the fabrication and characterization of an optical fiber pH sensor based on localized surface plasmon resonance. Gold nanoparticles (AuNPs) are embedded in a polyelectrolyte multilayer (PEM) consisting of chitosan and poly(sodium 4-styrenesulfonate). The absorbance and scattering properties of the AuNPs are affected by the pH-dependent swell state of the PEM. Both transmission- and reflection-based sensors are investigated and the measured transmittance/reflectance pH response can be closely fitted with the extended Henderson-Hasselbach equation. The reflection-based sensor can potentially be used for in vivo applications.

  15. A fiber-optic pH sensor based on polyelectrolyte multilayers embedded with gold nanoparticles

    International Nuclear Information System (INIS)

    We report the fabrication and characterization of an optical fiber pH sensor based on localized surface plasmon resonance. Gold nanoparticles (AuNPs) are embedded in a polyelectrolyte multilayer (PEM) consisting of chitosan and poly(sodium 4-styrenesulfonate). The absorbance and scattering properties of the AuNPs are affected by the pH-dependent swell state of the PEM. Both transmission- and reflection-based sensors are investigated and the measured transmittance/reflectance pH response can be closely fitted with the extended Henderson–Hasselbach equation. The reflection-based sensor can potentially be used for in vivo applications. (paper)

  16. Formation of κ-carrageenan-gelatin polyelectrolyte complexes studied by (1)H NMR, UV spectroscopy and kinematic viscosity measurements.

    Science.gov (United States)

    Voron'ko, Nicolay G; Derkach, Svetlana R; Vovk, Mikhail A; Tolstoy, Peter M

    2016-10-20

    The intermolecular interactions between an anionic polysaccharide from the red algae κ-carrageenan and a gelatin polypeptide, forming stoichiometric polysaccharide-polypeptide (bio)polyelectrolyte complexes in the aqueous phase, were examined. The major method of investigation was high-resolution (1)H NMR spectroscopy. Additional data were obtained by UV absorption spectroscopy, light scattering dispersion and capillary viscometry. Experimental data were interpreted in terms of the changing roles of electrostatic interactions, hydrophobic interactions and hydrogen bonds when κ-carrageenan-gelatin complexes are formed. At high temperatures, when biopolymer macromolecules in solution are in the state of random coil, hydrophobic interactions make a major contribution to complex stabilization. At the temperature of gelatin's coil→helix conformational transition and at lower temperatures, electrostatic interactions and hydrogen bonds play a defining role in complex formation. A proposed model of the κ-carrageenan-gelatin complex is discussed. PMID:27474666

  17. Absorption spectra and spectral-kinetic characteristics of the fluorescence of Sanguinarine in complexes with polyelectrolytes and DNA

    Science.gov (United States)

    Motevich, I. G.; Strekal, N. D.; Nowicky, J. W.; Maskevich, S. A.

    2010-07-01

    The absorption spectra and stationary and time resolved fluorescence spectra of the isoquinoline alkaloid sanguinarine are studied in aqueous media and during interactions with synthetic polyelectrolytes (polystyrene sulfonate and polyallylamine) and a natural polyelectrolyte (DNA).

  18. Absorption spectra and spectral-kinetic characteristics of the fluorescence of Sanguinarine in complexes with polyelectrolytes and DNA

    International Nuclear Information System (INIS)

    The absorption spectra and stationary and time resolved fluorescence spectra of the isoquinoline alkaloid sanguinarine are studied in aqueous media and during interactions with synthetic polyelectrolytes (polystyrene sulfonate and polyallylamine) and a natural polyelectrolyte (DNA). (authors)

  19. Complexation of radionuclides with natural polyelectrolytes - proteins, polysaccharides and humic substances

    International Nuclear Information System (INIS)

    Various approaches to the modeling of metal and radionuclide interactions with macromolecular ligands, proteins, polysaccharides and humic substances in particular, their chemical and sorption equilibria, and the techniques used for their investigation are concisely compared. To predict radionuclide mobility in the natural and semi-natural aqueous environment, the estimation of the effective interaction constants, related to specific species of polyelectrolytes which are linked with the absorbancy or absorbancy ratio in their electronic absorption spectra, should probably be preferred and developed as standard. For characterization of the binding sites of specific molecular forms of polyelectrolyte ligands, the Scatchard plot analysis at macroconcentrations of the metal and also, though not so effectively, the two-phase distribution at trace concentrations of radionuclide or metal can be applied. (author)

  20. On the Structure and Dynamics of Polyelectrolyte Gel Systems and Gel-surfactant Complexes

    OpenAIRE

    Råsmark, Per Johan

    2004-01-01

    This thesis describes the results of experimental work on polyelectrolyte gels and their interaction with oppositely charged surfactants, and presents two new algorithms applicable to the simulation of colloid and polymer systems. The model systems investigated were crosslinked poly(acrylate) (PA) and poly(styrene sulphonate) (PSS), and the surfactant was dodecyl trimethylammonium bromide (DoTAB). Pure gel materials were studied using dynamic light scattering. It was shown that the diffusion ...

  1. Complexation Between Weakly Basic Dendrimers and Linear Polyelectrolytes: Effects of Chain Stiffness, Grafts, and pOH

    Science.gov (United States)

    Lewis, Thomas; Pandav, Gunja; Omar, Ahmad; Ganesan, Venkat

    2013-03-01

    The unique architecture and high charge density of dendrimer molecules have attracted interest for their utilization in gene delivery applications. The strong binding affinity of cationic dendrimers to genetic materials make them effective gene delivery vectors not only by shielding the nucleic acid (NA) material from degradative enzymes in the blood stream, but also by reducing the overall negative charge of the dendrimer-NA material complex, which in turn creates more favorable interaction with the anionic cell membrane. However, the high cytotoxicities of cationic dendrimers have motivated the development of polyethylene glycol (PEG) conjugated dendrimer molecules, which have been shown to reduce dendrimer cytotoxicity while still retaining transfection ability. In order to gain insight into how the addition of neutral grafts affects the binding affinity and conformations of dendrimer-NA material complexes, we have developed and numerically solved a Self-Consistent Field Theory approach for both grafted and non-grafted annealed charged dendrimer molecules in the presence of linear polyelectrolyte molecules. Specifically, this work examines the effect of linear polyelectrolyte stiffness, grafting chain length, and solution pOH.

  2. Cell Permeating Nano-Complexes of Amphiphilic Polyelectrolytes Enhance Solubility, Stability, and Anti-Cancer Efficacy of Curcumin.

    Science.gov (United States)

    Fatima, Munazza T; Chanchal, Abhishek; Yavvari, Prabhu S; Bhagat, Somnath D; Gujrati, Mansi; Mishra, Ram K; Srivastava, Aasheesh

    2016-07-11

    Many hydrophobic drugs encounter severe bioavailability issues owing to their low aqueous solubility and limited cellular uptake. We have designed a series of amphiphilic polyaspartamide polyelectrolytes (PEs) that solubilize such hydrophobic drugs in aqueous medium and enhance their cellular uptake. These PEs were synthesized through controlled (∼20 mol %) derivatization of polysuccinimide (PSI) precursor polymer with hydrophobic amines (of varying alkyl chain lengths, viz. hexyl, octyl, dodecyl, and oleyl), while the remaining succinimide residues of PSI were opened using a protonable and hydrophilic amine, 2-(2-amino-ethyl amino) ethanol (AE). Curcumin (Cur) was employed as a representative hydrophobic drug to explore the drug-delivery potential of the resulting PEs. Unprecedented enhancement in the aqueous solubility of Cur was achieved by employing these PEs through a rather simple protocol. In the case of PEs containing oleyl/dodecyl residues, up to >65000× increment in the solubility of Cur in aqueous medium could be achieved without requiring any organic solvent at all. The resulting suspensions were physically and chemically stable for at least 2 weeks. Stable nanosized polyelectrolyte complexes (PECs) with average hydrodynamic diameters (DH) of 150-170 nm (without Cur) and 220-270 nm (after Cur loading) were obtained by using submolar sodium polyaspartate (SPA) counter polyelectrolyte. The zeta potential of these PECs ranged from +36 to +43 mV. The PEC-formation significantly improved the cytocompatibility of the PEs while affording reconstitutable nanoformulations having up to 40 wt % drug-loading. The Cur-loaded PECs were readily internalized by mammalian cells (HEK-293T, MDA-MB-231, and U2OS), majorly through clathrin-mediated endocytosis (CME). Cellular uptake of Cur was directly correlated with the length of the alkyl chain present in the PECs. Further, the PECs significantly improved nuclear transport of Cur in cancer cells, resulting in their

  3. Polyelectrolyte gels

    Energy Technology Data Exchange (ETDEWEB)

    Segalman, D.J.; Witkowski, W.R.

    1995-06-01

    Polyelectrolyte (PE) gels are swollen polymer/solvent networks that undergo a reversible volume collapse/expansion through various types of stimulation. Applications that could exploit this large deformation and solvent expulsion/absorption characteristics include robotic {open_quotes}fingers{close_quotes} and drug delivery systems. The goals of the research were to first explore the feasibility of using the PE gels as {open_quotes}smart materials{close_quotes} - materials whose response can be controlled by an external stimulus through a feedback mechanism. Then develop a predictive capability to simulate the dynamic behavior of these gels. This involved experimentally characterizing the response of well-characterized gels to an applied electric field and other stimuli to develop an understanding of the underlying mechanisms which cause the volume collapse. Lastly, the numerical analysis tool was used to simulate various potential engineering devices based on PE gels. This report discusses the pursuit of those goals through experimental and computational means.

  4. Multifunctional biosensors based on peptide-polyelectrolyte conjugates.

    Science.gov (United States)

    Kogikoski, S; Sousa, C P; Liberato, M S; Andrade-Filho, T; Prieto, T; Ferreira, F F; Rocha, A R; Guha, S; Alves, W A

    2016-01-28

    A novel enzymatic platform for the sensing of H2O2 and glucose that uses L,L-diphenylalanine micro/nanostructures (FF-MNSs) as an enzyme support is shown. This platform is obtained by the self-assembly of poly(allylamine hydrochloride) (PAH), FF-MNSs, and microperoxidase-11 (MP11) anchored onto the peptide matrix, in two different crystal structures of FF-MNSs: hexagonal (P61) and orthorhombic (P22121). The electroactive area of the electrodes increases in the presence of FF-MNSs. We also demonstrate via theoretical calculations that the valence band energy of the orthorhombic structure allows it to be doped, similarly to p-type semiconductors, where PAH acts as a doping agent for the orthorhombic peptide structure, decreasing the band-gap by around 1 eV, which results in a smaller charge transfer resistance. These results are consistent with electrochemical impedance spectroscopy measurements, which further elucidate the role of the band structure of the orthorhombic FF-MNSs in the conductivity and electron transfer rates of the hybrid material. An effective communication between the electrode and the active site of a glucose oxidase enzyme through MP11-protein complexes occurs, paving the way for FF-MNSs in the orthorhombic phase for the future development of bioelectronics sensing devices. PMID:26744288

  5. Diblock Polyelectrolytic Copolymers Containing Cationic Iron and Cobalt Sandwich Complexes: Living ROMP Synthesis and Redox Properties.

    Science.gov (United States)

    Gu, Haibin; Ciganda, Roberto; Hernandez, Ricardo; Castel, Patricia; Zhao, Pengxiang; Ruiz, Jaime; Astruc, Didier

    2016-04-01

    Diblock metallopolymer polyelectrolytes containing the two redox-robust cationic sandwich units [CoCp'Cp](+) and [FeCp'(η(6) -C6 Me6 )](+) (Cp = η(5) -C5 H5 ; Cp' = η(5) -C5 H4 -) as hexafluorophosphate ([PF6 ](-) ) salts are synthesized by ring-opening metathesis polymerization using Grubbs' third generation catalyst. Their electrochemical properties show full chemical and electrochemical reversibilities allowing fine determination of the copolymer molecular weight using Bard-Anson's electrochemical method by cyclic voltammetry. PMID:26841204

  6. Novel polyelectrolytes

    Science.gov (United States)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping Siao (Inventor)

    1978-01-01

    Cationic polyelectrolytes are formed by the polymerization in absence of oxygen of a monomer of the general formula: ##STR1## where x is 3 or more than 6 and Z is I, Br or Cl to form high charge density linear polymers. Segments of the linear polymer may be attached to or formed in the presence of polyfunctional reactive tertiary amines or halogen polymeric substrates or polyfunctional lower molecular reactive polyfunctional substrates to form branched or star polyelectrolytes by a quaternization polymerization reaction.

  7. Effect of temperature on the reentrant condensation in polyelectrolyte-liposome complexation.

    Science.gov (United States)

    Sennato, S; Truzzolillo, D; Bordi, F; Cametti, C

    2008-11-01

    Interactions of oppositely charged macroions in aqueous solution give rise to intriguing aggregation phenomena, resulting in finite-size, long-lived clusters, characterized by a quite narrow size distribution. Particularly, the adsorption of highly charged linear polyelectrolytes on oppositely charged colloidal particles is strongly correlated and some short-range order arises from competing electrostatic interactions between like-charged polymer chains (repulsion) and between polymer chains and particle surface (attraction). In these systems, in an interval of concentrations around the isoelectric point, relatively large clusters of polyelectrolyte-decorated particles form. However, the mechanisms that drive the aggregation and stabilize, at the different polymer/particle ratios, a well-defined size of the aggregates are not completely understood. Nor is clear the role that the correlated polyion adsorption plays in the aggregation, although the importance of "patchy interactions" has been stressed as the possible source of attractive interaction term between colloidal particles. Different models have been proposed to explain the formation of the observed cluster phase. However, a central question still remains unanswered, i.e., whether the clusters are true equilibrium or metastable aggregates. To elucidate this point, in this work, we have investigated the effect of the temperature on the cluster formation. We employed liposomes built up by DOTAP lipids interacting with a simple anionic polyion, polyacrylate sodium salt, over an extended concentration range below and above the isoelectric condition. Our results show that the aggregation process can be described by a thermally activated mechanism. PMID:18831566

  8. Ductile polyelectrolyte macromolecule-complexed zinc phosphate conversion crystal pre-coatings and topcoatings embodying a laminate

    Science.gov (United States)

    Sugama, Toshifumi; Kukacka, L.E.; Carciello, N.R.

    1985-11-05

    This invention relates to a precoat, laminate, and method for ductile coatings on steel and non-ferrous metals which comprises applying a zinc phosphating coating solution modified by a solid polyelectrolyte selected from polyacrylic acid (PAA), polymethacrylic acid (PMA), polyitaconic acid (PIA), and poly-L-glutamic acid. The contacting of the resin with the phosphating solution is made for a period of up to 20 hours at about 80/sup 0/C. The polyelectrolyte or the precoat is present in about 0.5 to 5.0% by weight of the total precoat composition and after application, the precoat base is dried for up to 5 hours at about 150/sup 0/C to desiccate. Also, a laminate may be formed where polyurethane (PU) is applied as an elastomeric topcoating or polyfuran resin is applied as a glassy topcoating. It has been found that the use of PAA at a molecular weight of about 2 x 10/sup 5/ gave improved ductility modulus effect.

  9. The influence of ionic strength and mixing ratio on the colloidal stability of PDAC/PSS polyelectrolyte complexes.

    Science.gov (United States)

    Zhang, Yanpu; Yildirim, Erol; Antila, Hanne S; Valenzuela, Luis D; Sammalkorpi, Maria; Lutkenhaus, Jodie L

    2015-10-01

    Polyelectrolyte complexes (PECs) form by mixing polycation and polyanion solutions together, and have been explored for a variety of applications. One challenge for PEC processing and application is that under certain conditions the as-formed PECs aggregate and precipitate out of suspension over the course of minutes to days. This aggregation is governed by several factors such as electrostatic repulsion, van der Waals attractions, and hydrophobic interactions. In this work, we explore the boundary between colloidally stable and unstable complexes as it is influenced by polycation/polyanion mixing ratio and ionic strength. The polymers examined are poly(diallyldimethylammonium chloride) (PDAC) and poly(sodium 4-styrenesulfonate) (PSS). Physical properties such as turbidity, hydrodynamic size, and zeta potential are investigated upon complex formation. We also perform detailed molecular dynamics simulations to examine the structure and effective charge distribution of the PECs at varying mixing ratios and salt concentrations to support the experimental findings. The results suggest that the colloidally stable/unstable boundary possibly marks the screening effects from added salt, resulting in weakly charged complexes that aggregate. At higher salt concentrations, the complexes initially form and then gradually dissolve into solution.

  10. The influence of ionic strength and mixing ratio on the colloidal stability of PDAC/PSS polyelectrolyte complexes.

    Science.gov (United States)

    Zhang, Yanpu; Yildirim, Erol; Antila, Hanne S; Valenzuela, Luis D; Sammalkorpi, Maria; Lutkenhaus, Jodie L

    2015-10-01

    Polyelectrolyte complexes (PECs) form by mixing polycation and polyanion solutions together, and have been explored for a variety of applications. One challenge for PEC processing and application is that under certain conditions the as-formed PECs aggregate and precipitate out of suspension over the course of minutes to days. This aggregation is governed by several factors such as electrostatic repulsion, van der Waals attractions, and hydrophobic interactions. In this work, we explore the boundary between colloidally stable and unstable complexes as it is influenced by polycation/polyanion mixing ratio and ionic strength. The polymers examined are poly(diallyldimethylammonium chloride) (PDAC) and poly(sodium 4-styrenesulfonate) (PSS). Physical properties such as turbidity, hydrodynamic size, and zeta potential are investigated upon complex formation. We also perform detailed molecular dynamics simulations to examine the structure and effective charge distribution of the PECs at varying mixing ratios and salt concentrations to support the experimental findings. The results suggest that the colloidally stable/unstable boundary possibly marks the screening effects from added salt, resulting in weakly charged complexes that aggregate. At higher salt concentrations, the complexes initially form and then gradually dissolve into solution. PMID:26268471

  11. Fiber Optic Humidity Sensor Based on Self-Assembled Polyelectrolyte Multilayers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Polyelectrolyte multilayers were self-assembled onto planar glass substrates and multimode optic fibers. The multilayer thin films deposited on glass substrates were characterized by using UV-vis spectroscopy and X-ray photoelectron spectroscopy. The multilayer thin films containing hydrophilic side-groups possessed are affinity for water molecules. The adsorption and desorption of free water vapor gave rise to the changes in the refractive index and in the reflectance of the thin films. A multilayer thin film based fiber optic humidity sensor with an LED light source of 0.85 μm was designed. Under certain conditions, the reflected light intensity of the thin film sensor was a function of the humidity of air. About 30 bilayers was optimal for the multilayer thin film sensor working at wavelength of 0.85 μm. This sensor can work over almost the whole relative humidity range with very good sensitivity.

  12. Polyelectrolyte complexes of N,N,N-trimethyl chitosan/heparin obtained at different p H: I. Preparation, characterization and controlled release of heparin

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    N,N,N-trimethyl chitosan (TMC) was synthesized through the N-methylation of chitosan (CHT) and characterized by FTIR spectroscopy. Polyelectrolytes complexes (PECs) based on TMC and Heparin (HP) were prepared at different pHs (5, 8, 10 and 12) and characterized through FTIR spectroscopy, DSC and TGA curves and WAXS profiles. It was verified that the thermal stability of PECs is higher as higher is the pH of feed solution used for PEC formation. At basic conditions the complexation between TMC and HP is more effective and alterations on WAXS profiles of PECs in relation to the precursor (TMC) were clearly observed. Also, WAXS profiles show that the PEC crystallinity depends on the pH used for the complexation. These results match to the FTIR, DSC and TGA data. Due to the more intense electrostatic interactions, at higher pHs the unlike polymers chains (TMC and HP) are closer enough to produce more stable PECs. Through of the delivery curves was showed that PEC8 is a promising material for uses in oral site-specific HP release systems. This fact is directly related to the thermal properties of PEC8. (author)

  13. Polyelectrolyte complexes of N,N,N-trimethyl chitosan/heparin obtained at different p H: I. Preparation, characterization and controlled release of heparin

    International Nuclear Information System (INIS)

    N,N,N-trimethyl chitosan (TMC) was synthesized through the N-methylation of chitosan (CHT) and characterized by FTIR spectroscopy. Polyelectrolytes complexes (PECs) based on TMC and Heparin (HP) were prepared at different pHs (5, 8, 10 and 12) and characterized through FTIR spectroscopy, DSC and TGA curves and WAXS profiles. It was verified that the thermal stability of PECs is higher as higher is the pH of feed solution used for PEC formation. At basic conditions the complexation between TMC and HP is more effective and alterations on WAXS profiles of PECs in relation to the precursor (TMC) were clearly observed. Also, WAXS profiles show that the PEC crystallinity depends on the pH used for the complexation. These results match to the FTIR, DSC and TGA data. Due to the more intense electrostatic interactions, at higher pHs the unlike polymers chains (TMC and HP) are closer enough to produce more stable PECs. Through of the delivery curves was showed that PEC8 is a promising material for uses in oral site-specific HP release systems. This fact is directly related to the thermal properties of PEC8. (author)

  14. STUDY OF THE DIGESTED SLUDGE DEWATERING EFFECTIVENESS USING POLYELECTROLYTE GEL BASED ON ORGANIC POLYMERS

    Directory of Open Access Journals (Sweden)

    Marcin Głodniok

    2016-02-01

    Full Text Available The paper addresses the problems connected with sewage sludge dewatering. The premise of the study was the analysis of whether there are opportunities to increase the efficiency of dewatering sludge, a relatively low-cost involving the use of innovative polymers. The authors analyzed the impact of the new type of polyelectrolyte gel on the effectiveness of dewatering sludge. Laboratory studies were carried out at polyelectrolyte dose selection and laboratory testing on the press chamber designed to simulate the actual operation of sludge dewatering system. Two different doses of polyelectrolyte were tested for dose I – 4 ml/m3 and dose II – 8 ml/m3. The conducted analysis on laboratory press showed an increase of sludge dewatering efficiency by about 2% for dose no. I and by about 13% for dose no. II, in comparison to the test without polyelectrolyte.

  15. Controlled Release of the Indomethacin Microencapsulation Based on Layer-by-layer Assembly by Polyelectrolyte Multilayers

    Institute of Scientific and Technical Information of China (English)

    CHEN You-fang; LIN Xian-fu

    2007-01-01

    Indomethacin has been encapsulated with polyelectrolyte multilayers for controlled release. Gelatin and alginate were alternatively deposited on indomethacin microcrystals. The released amount of indomethacin from coated microcrystals in pH6. 8phosphate buffer solution (PBS) was measured with a UV spectrophometer. The polyelectrolyte multilayer capsule thickness was proved to control the release rate. The effects of osmotic pressure existed during the release process of indomethacin from microcapsules coated by (gelatin/alginate) 4.

  16. Sustained, Controlled and Stimuli-Responsive Drug Release Systems Based on Nanoporous Anodic Alumina with Layer-by-Layer Polyelectrolyte

    Science.gov (United States)

    Porta-i-Batalla, Maria; Eckstein, Chris; Xifré-Pérez, Elisabet; Formentín, Pilar; Ferré-Borrull, J.; Marsal, Lluis F.

    2016-08-01

    Controlled drug delivery systems are an encouraging solution to some drug disadvantages such as reduced solubility, deprived biodistribution, tissue damage, fast breakdown of the drug, cytotoxicity, or side effects. Self-ordered nanoporous anodic alumina is an auspicious material for drug delivery due to its biocompatibility, stability, and controllable pore geometry. Its use in drug delivery applications has been explored in several fields, including therapeutic devices for bone and dental tissue engineering, coronary stent implants, and carriers for transplanted cells. In this work, we have created and analyzed a stimuli-responsive drug delivery system based on layer-by-layer pH-responsive polyelectrolyte and nanoporous anodic alumina. The results demonstrate that it is possible to control the drug release using a polyelectrolyte multilayer coating that will act as a gate.

  17. Functional finishing of aminated polyester using biopolymer-based polyelectrolyte microgels.

    Science.gov (United States)

    Glampedaki, Pelagia; Dutschk, Victoria; Jocic, Dragan; Warmoeskerken, Marijn M C G

    2011-10-01

    This study focuses on a microgel-based functionalization method applicable to polyester textiles for improving their hydrophilicity and/or moisture-management properties, eventually enhancing wear comfort. The method proposed aims at achieving pH-/temperature-controlled wettability of polyester within a physiological pH/temperature range. First, primary amine groups are created on polyester surfaces using ethylenediamine; second, biopolymer-based polyelectrolyte microgels are incorporated using the natural cross-linker genipin. The microgels consist of the pH-responsive natural polysaccharide chitosan and pH/thermoresponsive poly(N-isopropylacrylamide-co-acrylic acid) microparticles. Scanning electron microscopy confirmed the microgel presence on polyester surfaces. X-ray photoelectron spectroscopy revealed nitrogen concentration, supporting increased microscopy results. Electrokinetic analysis showed that functionalized polyester surfaces have a zero-charge point at pH 6.5, close to the microgel isoelectric point. Dynamic wetting measurements revealed that functionalized polyester has shorter total water absorption time than the reference. This absorption time is also pH dependent, based on dynamic contact angle and micro-roughness measurements, which indicated microgel swelling at different pH values. Furthermore, at 40 °C functionalized polyester has higher vapor transmission rates than the reference, even at high relative humidity. This was attributed to the microgel thermoresponsiveness, which was confirmed through the almost 50% decrease in microparticle size between 20 and 40 °C, as determined by dynamic light scattering measurements. PMID:21751392

  18. Insight into fractal self-assembly of poly(diallyldimethylammonium chloride)/sodium carboxymethyl cellulose polyelectrolyte complex nanoparticles.

    Science.gov (United States)

    Zhao, Qiang; An, Quanfu; Qian, Jinwen; Wang, Xuesan; Zhou, Yang

    2011-12-22

    Poly(diallyldimethylammonium chloride)-sodium carboxymethyl cellulose polyelectrolyte complexes (PDDA-CMCNa PECs) solids were prepared and dispersed in NaOH aqueous solution. Self-assembly of PECs nanoparticles during the solvent evaporation was examined by field emission electron microscopy (FESEM), atomic force microscopy (AFM), and fractal dimension analysis. It was found that tree-shaped fractal patterns formed after the solvent (water) was dried at ambient temperatures, and the fractal pattern is composed of needle-shaped PEC aggregate (PECA) nanoparticles. Time-dependent FESEM observation revealed that the fractal pattern started with the formation of initial nucleon and it is growing, during which the diffusion limited aggregation (DLA) mechanism revealed and made the pattern branched. Physical insight into the DLA mechanism was discussed in detail. Effects of PEC concentrations, PEC compositions, solvent evaporation temperatures, pH of PEC dispersion, and chemical structures of PECs on the formation of self-assembled fractal pattern were studied. Generally, it was found that the morphologies, charge characters of PEC particles, and the solvent evaporation conditions play important roles during the fractal self-assembly process. PMID:22098094

  19. Composition and structural transitions of polyelectrolyte-surfactant complexes in the presence of fatty acid studied by NMR and cryo-SEM.

    Science.gov (United States)

    Totland, Christian; Martinez-Santiago, Jose; Ananthapadmanabhan, Kavssery P; Somasundaran, Ponisseril

    2015-02-10

    Insoluble complexes formed when a cationic polyelectrolyte is neutralized by the oppositely charged surfactant sodium dodecylethersulfate (SDES) in the presence and absence of lauric acid (LA) have been examined directly using NMR spectroscopy and cryo-SEM. Below the SDES critical micelle concentration (CMC') the insoluble complex contains about 10 times more water than just above CMC'. This is related to a structural transition of the complex, where water is contained mainly in larger compartments below CMC' and then mainly in narrower compartments above CMC'. The structure of the complex's solid matrix was monitored by recording two-dimensional T2-diffusion correlation spectra of the water proton resonance, which reveal the presence of several different water environments which correspond to different complex structures. Structural features in the micrometer range were confirmed using cryo-SEM. When LA is present, the larger water compartments seen below CMC' are to some extent present in the entire SDES concentration range, which is not the case in the absence of LA. Furthermore, the inclusion of LA into the SDES aggregates above CMC' leads to a lamellar sheetlike organization of the polyelectrolyte-stabilized surfactant phase. In the absence of LA, a stringy network of fibers is seen in cryo-SEM images, indicating a spherical or rodlike SDES phase. Consequently, the complex without LA holds about 1.7-1.9 times more water than the complex with LA above the SDES CMC'. T1 relaxation, (13)C chemical shifts, and (1)H resonance line widths of SDES in the system support the above observations. The combination of MAS NMR, T2-diffusion correlation, and cryo-SEM proved to be an effective method for studying structural transitions in the surfactant-polyelectrolyte(-LA) insoluble complexes.

  20. Two-Phase Electrospinning to Incorporate Polyelectrolyte Complexes and Growth Factors into Electrospun Chitosan Nanofibers.

    Science.gov (United States)

    Place, Laura W; Sekyi, Maria; Taussig, Julia; Kipper, Matt J

    2016-03-01

    Growth factors are potent signaling proteins for tissue engineering, but they are susceptible to loss of activity when exposed to solvents used for polymer processing. This work explores preservation of fibroblast growth factor-2 (FGF-2) activity in chitosan nanofibers using two-phase electrospinning via a compound coaxial needle and from a water-in-oil emulsion FGF-2 in aqueous poly(vinyl alcohol) is added on either the inside (A/O) or the outside (O/A) of an organic chitosan phase, using the compound needle. FGF-2 is further stabilized by complexation to heparin-based nanoparticles. The emulsion method does not result in detectable incorporation of FGF-2. The A/O fibers incorporate the highest amount of FGF-2. Nanoparticle-stabilized FGF-2 in A/O nanofibers is most active toward bone-marrow stromal cells. PMID:26611767

  1. Optical biosensing transducer based on silicon waveguide structure coated with polyelectrolyte nano layers

    Science.gov (United States)

    Haron, Saharudin; Nabok, Alexey V.; Ray, Asim K.

    2003-04-01

    An optical biosensor based on attenuation of the light intensity during multiple reflections in a planar waveguide has been developed for water pollution monitoring. The planar waveguide consists of a 190 nanometer thick silicon nitride (Si3N4) core layer sandwiched between 1.5 micrometer thick silicon dioxide (SiO2) cladding layers. Composite polyelectrolyte self-assembled membranes containing Cyclotetrachromotropylene (CTCT) as an indicator and enzymes, such as Urease or Acetylcholine Esterase (AChE) were deposited on top of silicon nitride core layer within a 4 × 6 mm sensing window. Experimental studies on the light propagation through the planar waveguide show the advantages of this method over conventional UV-visible absorption spectroscopy. It was found that the planar waveguide sensitivity is higher by several orders of magnitude than that for UV-visible absorption spectroscopy. The respective enzyme reactions as well as their inhibition by heavy metal ions were studied by monitoring the light intensity in the planar waveguide. Cadmium (Cd2+) and lead (Pb2+) ions were registered in very low concentrations down to 1 ppb with the planar waveguide transducer. The enzymes used were inhibited differently by the above pollutants, which is promising for the development of enzyme sensor arrays.

  2. Surface Property and Stability of Transparent Superhydrophobic Coating Based on SiO2-Polyelectrolyte Multilayer

    Directory of Open Access Journals (Sweden)

    Sunisa JINDASUWAN

    2016-05-01

    Full Text Available Artificial superhydrophobic films were deposited onto a glass slide by performing layer-by-layer deposition of 3.5 bilayers of poly(allylamine hydrochloride/ poly(acrylic acid polyelectrolyte, followed by a layer of SiO2 nanoparticles of various amounts to enhance the surface roughness and a fluorosilane to reduce the surface free energy. Higher SiO2 content incorporated into the films resulted in rougher surface and higher water contact angle. The total surface free energy determined by using the Owens-Wendt equation dramatically decreased from 31.46 mJ·m-2 for the film having the relatively flat surface to only 1.16 mJ·m-2 for the film having the highest surface roughness of 60.2 ± 1.1 nm. All the films were optically transparent and had excellent adhesion based on the peel test. Indoor and accelerated weathering tests revealed good weathering stability.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.12952

  3. Chitosan-gum arabic polyelectrolyte complex films: physicochemical, mechanical and mucoadhesive properties.

    Science.gov (United States)

    Sakloetsakun, Duangkamon; Preechagoon, Detpon; Bernkop-Schnürch, Andreas; Pongjanyakul, Thaned

    2016-08-01

    By blending chitosan (CS) and gum arabic (GA), a powerful biomaterial complex might be obtained due to the unique properties of CS and the low viscosity and good emulsifying properties of GA. The objectives of this study were to prepare and examine the properties of dispersions and films of CS and GA as a function of the mixing weight ratio, pH value and molecular weight of CS. The dispersions were characterized by turbidity, zeta potential and cytotoxicity and then the dispersions were cast into films. Physicochemical properties of the film were performed. CS-GA dispersions exhibited higher turbidity and a lower zeta potential with an increase in the GA ratio. Continuous films of the CS-GA could be formed at all ratios. CS and GA could molecularly interact via electrostatic forces and intermolecular hydrogen bonding. The CS-GA (1:0.5) films exhibited relatively low water uptake, erosion, water vapor permeability and puncture strength compared to the CS films. Furthermore, the CS-GA films demonstrated good mucoadhesive properties, allowing for adhesion to the mucosal membrane. Based on these results, it could be advantageous to use CS-GA films as film formers for the formulation of coatings and drug delivery systems. PMID:25886079

  4. Effects of Polyelectrolyte Complex Micelles and Their Components on the Enzymatic Activity of Lipase

    NARCIS (Netherlands)

    Lindhoud, Saskia; Norde, Willem; Cohen Stuart, Martien A.

    2010-01-01

    The enzymatic activity of Hl-lipase embedded in complexes of poly-2-methylvinylpyridinium-co-poly(ethylene oxide) (P2MVP41−PEO205) and poly(acrylic acid)(PAA139) is studied as a function of the PAA139 + P2MVP41−PEO205 complex composition. The measurements revealed that there are several factors that

  5. Effects of Polyelectrolyte Complex Micelles and Their Components on the Enzymatic Activity of Lipase

    NARCIS (Netherlands)

    Lindhoud, Saskia; Norde, Willem; Stuart, Martien A. Cohen

    2010-01-01

    The enzymatic activity of Hi-lipase embedded in complexes of poly-2-methylvinylpyridinium-co-poly(ethylene oxide) (P2MVP(41)-PEG(205)) and poly(acrylic acid)(PAA(139)) is studied as a function of the PAA(139) + P2MVP(41) - PEO(205) complex composition. The measurements revealed that there are severa

  6. Effects of polyelectrolyte complex micelles and their components on the enzymatic activity of lipase

    NARCIS (Netherlands)

    Lindhoud, S.; Norde, W.; Cohen Stuart, M.A.

    2010-01-01

    The enzymatic activity of Hl-lipase embedded in complexes of poly-2-methylvinylpyridinium-co-poly(ethylene oxide) (P2MVP41-PEO205) and poly(acrylic acid)(PAA139) is studied as a function of the PAA139 + P2MVP41-PEO205 complex composition. The measurements revealed that there are several factors that

  7. Synthesis and characterisation of polyelectrolytes based on polymers of diallyldimethyl ammonium chloride and poly(styrene-co-butadiene)

    OpenAIRE

    Svensson, David

    2012-01-01

    In printed electronics there are many polyelectrolytes to choose from. While polyelectrolytes such as polystyrene sulfonic acid can fulfill many ofthe desired functionalities of a semiconductor, there is a need for other polyelectrolytes with other functionalities, such as functionality at low airhumidity and better cross-linking possibilities, while still functioning as a good semiconductor.Within this thesis, there is a description of general polyelectrolytes, as well as various usages.The ...

  8. On the phase diagram of reentrant condensation in polyelectrolyte-liposome complexation

    Science.gov (United States)

    Sennato, S.; Bordi, F.; Cametti, C.

    2004-09-01

    Complexation of polyions with oppositely charged spherical liposomes has been investigated by means of dynamic light scattering measurements and a well-defined reentrant condensation has been observed. The phase diagram of charge inversion, recently derived [T. T. Nguyen and B. I. Shklovskii, J. Chem. Phys. 115, 7298 (2001)] for the complexation of DNA with charged spherical macroions, has been employed in order to define the boundaries of the region where polyion-liposome complexes begin to condense, forming larger aggregates, and where aggregates dissolve again, towards isolated polyion-coated-liposome complexes. A reasonable good agreement is observed in the case of complexes formed by negatively charged polyacrylate sodium salt polyions and liposomes built up by cationic lipids (dioleoyltrimethylammoniumpropane), in an extended liposome concentration range.

  9. Interaction of proteins with linear polyelectrolytes and spherical polyelectrolyte brushes in aqueous solution

    OpenAIRE

    Wittemann, Alexander; Ballauff, Matthias

    2006-01-01

    We review recent experiments on the interaction of proteins with anionic polyelectrolytes in aqueous solution. Data from the literature demonstrate that proteins can form soluble complexes with linear polyelectrolytes even on the “wrong side” of the isoelectric point, that is, for pH values above the isoelectric point of the proteins under which the polyelectrolytes and the proteins are like-charged. All data published so far demonstrate that this type of adsorption becomes weaker with increa...

  10. Many facets of the polyelectrolyte and oppositely charged colloidal particle complexation: counterion release and electrical conductivity behavior.

    Science.gov (United States)

    Cametti, C; Truzzolillo, D

    2011-06-01

    The lateral correlated adsorption of polyions onto oppositely charged vesicles, leading to the formation of stable equilibrium clusters of mesoscopic size, is associated to the release of a fraction of counterions, initially condensed on the polyion chains. This ulterior release of counterions provokes an increase of the number of free ions, besides the ones due to the partial ionization of both charged particles and polyions, that can be appropriately monitored by means of electrical conductivity measurements of the whole system. We have investigated this behavior in a suspension of cationic vesicles made up by dioleoyl trimethyl ammonium propane (DOTAP) liposomial vesicles interacting with an anionic polyelectrolyte composed by polyacrylate sodium salt. This system has been in the past extensively studied by us by means of different experimental techniques, and its behavior has been sufficiently characterized, as far as hydrodynamic and electrical properties are concerned. In this note, we report on the dc electrical conductivity behavior during the whole aggregation process, from the single polyion-coated liposomal particles, to polyion-induced liposome clusters, to finally polyion-fully covered liposomes, in polyion excess conditions. We have evaluated the excess of released counterions on the basis of the standard theory of the electrical properties of aqueous charged solutions and compared this quantity with the one predicted by the lateral correlation adsorption model. The agreement is quite good, offering strong experimental evidence of the role played by the release of counterions in the aggregation process. Finally, we have considered a similar liposomial system, where the lateral correlation adsorption was inhibited by structural reasons, having replaced the polyion by a simple electrolyte, whose dissociated ions will adsorb randomly at the particle surface, rather than in a correlated manner. In this case, no counterion release upon complexation occurs

  11. Universal properties of complexes formed by two oppositely charged flexible polyelectrolytes

    International Nuclear Information System (INIS)

    Results of molecular dynamics simulations for systems with two flexible, oppositely charged polymer chains are presented. It is shown that the chains aggregate into densely packed structures. The universal properties of the formed complexes are investigated as a function of chain length and interaction strength. For weakly interacting systems, a chain length-dependent effective interaction strength is obtained which governs the initiation of the aggregation process. At intermediate interaction strengths, the formed complexes exhibit a scaling behaviour with respect to molecular weight typically for chain molecules in a bad solvent. An unusual weak dependence of the radius of gyration on the interaction strength is found in this regime. Finally, for strong interactions, tightly packed globules are obtained. The radii of gyration and the densities of the complexes are discussed

  12. In situ-ATR-FTIR analysis on the uptake and release of streptomycin from polyelectrolyte complex layers

    Science.gov (United States)

    Torger, B.; Müller, M.

    2013-03-01

    In-situ ATR-FTIR spectroscopy and line shape analysis of the diagnostic spectral region was used to quantify the bound amount and release of the antibiotic streptomycin (STRP) at polyelectrolyte (PEL) multilayers (PEM) of poly(ethyleneimine) (PEI) and poly(acrylic acid) (PAA) or PEI and sodium alginate (ALG). Unlike common concepts based on the drug enrichment of the release medium, this analytical concept allowed to measure quantitatively the drug depletion in the delivery matrix. The measured kinetic in situ ATR-FTIR data were analysed by a modified Korsmeyer-Peppas equation based on two characteristic release parameters k and n. As main experimental parameters the number of PEL layers (adsorption steps) z and the STRP/PEL ratio were varied. For z = 8 the STRP/PEL ratio showed the most significant influence on release kinetics, whereby for STRP/PEL = 1:25 slowest (n = 0.77) and lowest (k = 21.4%) and for STRP/PEL = 1:5 most rapid (n = 0.30) and highest (k = 58.6%) drug releases were found. PEM-PEI/ALG-8 (STRP/PEL = 1:5) revealed slower release rates (n = 0.58) and lower released STRP amounts (k = 17.1%) compared to PEI/PAA. UV-VIS data on time dependent STRP enrichment of the release medium showed a similar trend compared to respective ATR-FTIR data on STRP depletion in PEM. Released amounts of around 1-2 mg from the herein introduced PEM films could be determined. The introduced analytical concept will be used as screening tool for other drugs, drug eluting films and bone substituting materials.

  13. New liner and reticular polyelectrolytes based an acetoacetic ehter and acrylic acid: synthesis, structure and stimulating sensitivity characteristics

    International Nuclear Information System (INIS)

    Novel linear and crosslinked poly-carbolytes based on acetoacetic ester and acrylic acid were synthesized for the first time via Michael addition reaction followed by the radical poly-mineralization. The structure and properties of polyelectrolytes were characterized by FTIR, Raman and NMR spectroscopy, TGA, DSC, GPC, viscosimetry, and potentiometric titration. Considerable influence of water content on the swelling rate of hydrogel was established. The swelling-deswelling properties of hydrogels were studied in water-organic solvent mixtures, electric and magnetic fields. (author)

  14. Rodlike Complexes of a Polyelectrolyte (Hyaluronan) and a Protein (Lysozyme) observed by SANS

    CERN Document Server

    Boué, François; Cousin, Fabrice; Grillo, Isabelle; Morfin, Isabelle; 10.1021/bm100861g

    2012-01-01

    We study by Small Angle Neutron Scattering (SANS) the structure of Hyaluronan -Lysozyme complexes. Hyaluronan (HA) is a polysaccharide of 9 nm intrinsic persistence length that bears one negative charge per disaccharide monomer (Mmol = 401.3 g/mol); two molecular weights, Mw = 6000 and 500 000 Da were used. The pH was adjusted at 4.7 and 7.4 so that lysozyme has a global charge of +10 and + 8 respectively. The lysozyme concentration was varied from 3 to 40 g/L, at constant HA concentration (10 g/L). At low protein concentration, samples are monophasic and SANS experiments reveal only fluctuations of concentration although, at high protein concentration, clusters are observed by SANS in the dense phase of the diphasic samples. In between, close to the onset of the phase separation, a distinct original scattering is observed. It is characteristic of a rod-like shape, which could characterize "single" complexes involving one or a few polymer chains. For the large molecular weight (500 000) the rodlike rigid doma...

  15. In-vitro evaluation of the effect of polymer structure on uptake of novel polymer-insulin polyelectrolyte complexes by human epithelial cells.

    Science.gov (United States)

    Ibie, C; Knott, R; Thompson, C J

    2015-02-01

    The biocompatibility and cellular uptake of polymer, insulin polyelectrolyte complexes (PECs) prepared using polyallylamine-based polymers was evaluated in-vitro using Caco-2 cell monolayers as a predictive model for human small intestinal epithelial cells. Poly(allyl amine) (PAA) and Quaternised PAA (QPAA) were thiolated using either carbodiimide mediated conjugation to N-acetylcysteine (NAC) or reaction with 2-iminothiolane hydrochloride yielding their NAC and 4-thiobutylamidine (TBA) conjugates, respectively. The effect of polymer quaternisation and/or thiolation on the IC50 of PAA was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay carried out on Caco-2 cells (with and without a 24 h recovery period after samples were removed). Uptake of PECs by Caco-2 cells was monitored by microscopy using fluorescein isothiocyanate (FITC) labelled insulin and rhodamine-labelled polymers at polymer:insulin ratios (4:5) after 0.5, 1, 2 and 4 h incubation in growth media (±calcium) and following pre-incubation with insulin. MTT results indicated that quaternisation of PAA was associated with an improvement in IC50 values; cells treated with QPAA (0.001-4 mg mL(-1)) showed no signs of toxicity following a 24 h cell recovery period, while thiolation of QPAA resulted in a decrease in the IC50. Cellular uptake studies showed that within 2-4 h, QPAA and QPAA-TBA insulin PECs were taken up intracellularly, with PECs being localised within the perinuclear area of cells. Further investigation showed that uptake of PECs was unaffected when calcium-free media was used, while presaturating insulin receptors affected the uptake of QPAA, insulin PECs, but not QPAA-TBA PECs. The biocompatibility of PAA and uptake of insulin was improved by both thiol and quaternary substitution.

  16. Brownian dynamics simulations of complexes of hyperbranched polymers with linear polyelectrolytes: Effects of the strength of electrostatic interactions on static properties

    International Nuclear Information System (INIS)

    Static/structural characteristics of non-covalent complexes, formed by terminally charged hyperbranched polymers and oppositely charged neutralizing linear polyelectrolytes, are examined by means of Brownian dynamics computer simulations. Excluded-volume, electrostatic and hydrodynamic interactions are taken into account in implicit solvent. Three pairs of complexes consisting of linear chains and hyperbranched molecules each bearing different molecular weight and distinctly diverse topologies are examined under conditions of varying electrostatic interactions. The findings from the present work demonstrate that through an appropriate modification of internal structure and external stimuli, key attributes of such complexes like size, shape and local density distribution, can be tuned at desired levels, rendering them promising candidates for a wide range of pertinent nanoscale applications

  17. Changes in the Activity and Structure of Urease in the Interaction with Polyelectrolytes

    Science.gov (United States)

    Saburova, E. A.; Tikhonenko, S. A.; Dybovskaya, Yu. N.; Sukhorukov, B. I.

    2008-03-01

    The influence of polyelectrolytes on the structural and catalytic characteristics of urease ( Canavalia ensiformis) was studied by the methods of steady-state kinetics, fluorescence spectroscopy, and circular dichroism. It was shown that, of the four polyelectrolytes studied, two of which were negatively charged (polystyrene sulfonate and dextran sulfate) and two were positively charged (polyallylamine (PAA) and polydiallyl dimethylammonium chloride), only PAA was a potent urease inhibitor: 0.5 μg/ml of PAA provided a 50% degree of inhibition for enzyme at neutral pH. It was found that polyelectrolyte did not inhibit urease in the presence of micromolar concentrations of ammonium chloride. Based on the experimental data and the calculated structure of urease from Canavalia ensiformis and on the identity with the amino acid sequence of urease from Bacillus pasteurii, the mechanism of urease inactivation by the PAA polyelectrolyte is discussed. This mechanism does not resemble the inhibiting action of polyelectrolytes on the previously studied oligomeric proteins—lactate dehydrogenase, glutamate dehydrogenase, and hemoglobin. It is proposed that the specific cation-binding sites determining the structural dynamics of the enzyme-polyelectrolyte complex play the regulating role in the urease molecule.

  18. A novel biosensing interfacial design based on the assembled multilayers of the oppositely charged polyelectrolytes

    International Nuclear Information System (INIS)

    A novel biosensing interfacial design strategy has been produced by the alternate adsorption of the oppositely charged polyelectrolytes. A quartz-crystal microbalance (QCM) as a model transducer was modified by use of mercaptoacetic acid (MAA) self-assembled monolayer (SAM) and the adsorption multilayers of the oppositely charged polyelectrolytes. MAA-SAM was first applied to the gold electrode surface of the crystal, and the positively charged chitosan was used as a double-sided linker to attach the negatively charged alginate-HSA antibodies to the negatively charged MAA-SAM layer. The assembly process and conditions were studied using the real-time output device and the surface topologies of the resulting crystals were characterized by atomic force microscopy (AFM) imaging. It is discovered that the optimal pH of immobilizing antibodies was 7.2 and the suited dilution ratio of antibodies was 10:30. The proposed immunosensor in optimal conditions has a linear detection range of 12.3-184.5 μg/mL for HSA detection. Comparing with the direct immobilization method of antibodies, the immunosensor with the proposed immobilization procedure shows some advantages, such as improved sensitivity due to the well-retained antibody activity and the significantly extended detection range. In particular, the regeneration of the developed immunosensor was simple and fast. Analytical results indicate that the developed immobilization procedure is a promising alternative for the immobilization of biorecognition element on the electrode surface

  19. Proton conducting gel polyelectrolytes based on 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Zygadlo-Monikowska, Ewa; Florjanczyk, Zbigniew; Wielgus-Barry, Edyta; Hildebrand, Ewa [Warsaw University of Technology, Faculty of Chemistry, ul. Noakowskiego 3, 00-664 Warszawa (Poland)

    2006-09-13

    Polyelectrolytes of 2-acrylamido-2-methyl-propanesulfonic acid (AMPSA) in the form of crosslinked hydrogels have been obtained. The effect of the amount of crosslinking agent, N,N'-methylene-bis-acrylamide (BAA), and water content on the conductivity and mechanical properties of the gels obtained was studied and the results were compared with those of poly(AMPSA) aqueous solutions. The highest {sigma} values, of the order of 1Scm{sup -1} are reached by systems containing 60-80wt.% of water and 1-2wt.% BAA. These systems form flexible and transparent membranes. Modification of the mechanical properties of hydrogels consisting in the synthesis of structures of mutually interpenetrating polymer networks of poly(vinylidene fluoride) and poly(vinyl alcohol) (PVA) was performed. The thermal properties of these modified gels were studied. (author)

  20. Bulk heterojunction organic photovoltaic based on polythiophene-polyelectrolyte carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Reyes-Reyes, M. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico); Lopez-Sandoval, R. [Advanced Materials Department, IPICYT, Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi 78216 (Mexico); Liu, J.; Carroll, D.L. [Center for Nanotechnology and Molecular Materials, Wake Forest University, Winston-Salem, NC (United States)

    2007-09-22

    It is shown that carbon nanotubes can be used to enhance carrier mobility for efficient removal of the charges in thin film polymer-conjugated/fullerene photovoltaic devices. The fabricated photovoltaic devices consist of poly(3-octylthiophene) (P3OT) polymer blended with undoped multiwalled carbon nanotubes (MWNTs) and carbon nanotubes doped with nitrogen (CNx-MWNTs). Nanophase formation and dispersion problems associated with the use of carbon nanotubes in polymer devices were addressed through the generation of functional groups and electrostatic attaching of the polyelectrolyte poly(dimethyldiallylamine) chloride (PDDA) in both MWNTs and CNx-MWNT systems. The resultant nanophase was highly dispersed allowing for excellent bulk heterojunction formation. Our results indicate that CNx-MWNTs enhance the efficiency of P3OT solar cells in comparison with MWNTs. (author)

  1. Efficient inverted polymer solar cells based on conjugated polyelectrolyte and zinc oxide modified ITO electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Tao; Zhu, Xiaoguang; Tu, Guoli, E-mail: tgl@hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhou, Lingyu [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory of Clean Energy, Dalian 116023 (China); Zhang, Jian, E-mail: jianzhang@guet.edu.cn [Department of Material Science and Engineering, Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China)

    2015-02-23

    Efficient inverted polymer solar cells (PSCs) were constructed by utilizing a conjugated polyelectrolyte PF{sub EO}SO{sub 3}Na and zinc oxide to modify the indium tin oxide (ITO) electrode. The ITO electrode modified by PF{sub EO}SO{sub 3}Na and zinc oxide possesses high transparency, increased electron mobility, smoothened surface, and lower work function. PTB7:PC{sub 71}BM inverted PSCs containing the modified ITO electrode achieved a high power conversion efficiency (PCE) of 8.49%, exceeding that of the control device containing a ZnO modified ITO electrode (7.48%). Especially, PCE-10:PC{sub 71}BM inverted polymer solar cells achieved a high PCE up to 9.4%. These results demonstrate a useful approach to improve the performance of inverted polymer solar cells.

  2. Coencapsulation of oxygen carriers and glucose oxidase in polyelectrolyte complex capsules for the enhancement of D-gluconic acid and delta-gluconolactone production.

    Science.gov (United States)

    Bucko, Marek; Gemeiner, Peter; Vikartovská, Alica; Mislovicová, Danica; Lacík, Igor; Tkác, Ján

    2010-04-01

    A novel encapsulated oxidative biocatalyst comprising glucose oxidase (GOD) coencapsulated with oxygen carriers within polyelectrolyte complex capsules was developed for the production of D-gluconic acid and delta-gluconolactone. The capsules containing immobilized GOD were produced by polyelectrolyte complexation with sodium alginate (SA) and cellulose sulfate (CS) as polyanions, poly(methylene-co-guanidine) (PMCG) as the polycation, CaCl(2) as the gelling agent and NaCl as the antigelling agent (GOD-SA-CS/PMCG capsules). Poly(dimethylsiloxane) (PDMS) and an emulsion of n-dodecane (DOD) or perfluorodecaline (PFD) with PDMS were used as the oxygen carriers and MnO(2) was used as a hydrogen peroxide decomposition catalyst. Water-soluble PDMS was found to act as both an oxygen carrier and an emulsifier of water-insoluble DOD and PFD. Stable microcapsules could be produced with concentrations of up to 4% (w/w) of PDMS, 10% (w/w) of DOD and PFD, and 25% (w/w) of MnO(2) in the polyanion solution of SA and CS. Roughly a two-fold increase in the GOD activity from 21.0+/-1.1 to 38.4+/-2.0 U*g(-1) and product space-time yields (STY) from 44.3+/-2.0 to 83.4+/-3.4 g*H*day(-1) could be achieved utilizing coencapsulated oxygen carriers compared to GOD encapsulated in the absence of oxygen carriers. This enhanced production does not significantly depend on the selected oxygen carrier under the conditions used in this study.

  3. STUDY ON PHOTODYNAMIC AND PHOTORESPONSIVE AZO POLYELECTROLYTES

    Institute of Scientific and Technical Information of China (English)

    Xiao-gong Wang; Li-feng Wu; Qi-xiang Zhou; Lian Li; Srinivasan Balasubraminian; Jayant Kumar; Sukant K. Tripathy

    2000-01-01

    Several kinds of novel azobenzene-containing polyelectrolytes with special molecular design have been developed from acryloyl chloride or epoxy based precursor polymers. The acryloyl chloride based precursor polymer, poly(acryloyl chloride), was prepared by free radical polymerization of acryloyl chloride. The azo polyelectrolytes were prepared by an esterification reaction between the precursor polymer and corresponding azo chromophores containing a reactive hydroxyl group, followed by hydrolysis of the unreacted acyl chloride groups. The epoxy based precursor polymer was prepared by the reaction between 1,4-cyclohexanedimethanol diglycidyl ether and aniline, and postfunctionalized by azo coupling reaction to form azo polymers containing chromophores with ionizable groups. The polyelectrolytes were characterized by elemental analysis, 1H-NMR, IR and UV-Vis spectroscopy. The photodynamic and photoresponsive properties, as well as self-assembly ofthese azo polyelectrolytes are reported in this paper[1].

  4. Charged colloids, polyelectrolytes and biomolecules viewed as strongly coupled Coulomb systems

    CERN Document Server

    Löwen, H; Likos, C N; Blaak, R; Dzubiella, J; Jusufi, A; Hoffmann, N; Harreis, H M

    2003-01-01

    A brief review is given on recent studies of charged soft matter solutions, as modelled by the 'primitive' approach of strongly coupled Coulomb systems, where the solvent just enters as a dielectric background. These include charged colloids, biological macromolecules such as proteins and DNA, polyelectrolytes and polyelectrolyte stars. Also some original results are presented on colloid-polyelectrolyte complex formation near walls and on the anomalous fluid structure of polyelectrolyte stars as a function of increasing concentration.

  5. Charged colloids, polyelectrolytes and biomolecules viewed as strongly coupled Coulomb systems

    International Nuclear Information System (INIS)

    A brief review is given on recent studies of charged soft matter solutions, as modelled by the 'primitive' approach of strongly coupled Coulomb systems, where the solvent just enters as a dielectric background. These include charged colloids, biological macromolecules such as proteins and DNA, polyelectrolytes and polyelectrolyte stars. Also some original results are presented on colloid-polyelectrolyte complex formation near walls and on the anomalous fluid structure of polyelectrolyte stars as a function of increasing concentration

  6. Microstructure of polyelectrolyte nanoaggregates studied by fluorescence probe method.

    Science.gov (United States)

    Vasilescu, Marilena; Angelescu, Daniel G; Bandula, Rodica; Staikos, Georgios

    2011-11-01

    The microstructure of water soluble nanoaggregates based on polyelectrolyte complex formed by the cationic comb-type copolymer poly(acrylamide -co-[3- (methacryloyl-amino)propyl] trimethylammonium chloride)-graft- polyacrylamide [P(AM-co-MAPTAC)-g-PAM] and the anionic linear polyelectrolyte sodium polyacrylate (NaPA) was investigated using the fluorescence probe technique. The fluorescence probe were 1-anilinonaphthalene-8-sulfonic acid (ANS), pyrene (Py) and 1,10-bis(1-pyrene) decane (PD). The fluorescence properties in polyelectrolyte complex solutions, which are sensitive to either micropolarity (ANS, Py) or microviscosity (PD), were related to the quantities obtained in different pure or mixed solvents. Micropolarities were quantified utilizing the polarity common index (Reichardt) E(T)(30). ANS and Py showed a variation of the micropolarity with the charge ratio of the two polymers, with the lowest polarity reached at the complex neutralization. The PD probe, by its excimer-to-monomer fluorescence intensities ratio, enabled us to evidence the effect of the composition and the comb-type copolymer grafting density on the microviscosity of the interpolyelectrolytes aggregates. It has been found that the microviscosity increased with the density of the grafting PAM chains. PMID:21688051

  7. Nanohybrid conjugated polyelectrolytes: highly photostable and ultrabright nanoparticles

    Science.gov (United States)

    Darwish, Ghinwa H.; Karam, Pierre

    2015-09-01

    We present a general and straightforward one-step approach to enhance the photophysical properties of conjugated polyelectrolytes. Upon complexation with an amphiphilic polymer (polyvinylpyrrolidone), an anionic conjugated polyelectrolyte (poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene]) was prepared into small nanoparticles with exceptional photostability and brightness. The polymer fluorescence intensity was enhanced by 23 -fold and could be easily tuned by changing the order of addition. Single molecule experiments revealed a complete suppression of blinking. In addition, after only losing 18% of the original intensity, a remarkable amount of photons were emitted per particle (~109, on average). This number is many folds greater than popular organic fluorescent dyes. We believe that an intimate contact between the two polymers is shielding the conjugated polyelectrolyte from the destructive photooxidation. The prepared nanohybrid particles will prove instrumental in single particle based fluorescent assays and can serve as a probe for the current state-of-the-art bioimaging fluorescence techniques.We present a general and straightforward one-step approach to enhance the photophysical properties of conjugated polyelectrolytes. Upon complexation with an amphiphilic polymer (polyvinylpyrrolidone), an anionic conjugated polyelectrolyte (poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene]) was prepared into small nanoparticles with exceptional photostability and brightness. The polymer fluorescence intensity was enhanced by 23 -fold and could be easily tuned by changing the order of addition. Single molecule experiments revealed a complete suppression of blinking. In addition, after only losing 18% of the original intensity, a remarkable amount of photons were emitted per particle (~109, on average). This number is many folds greater than popular organic fluorescent dyes. We believe that an intimate contact between the two polymers is shielding the

  8. Surface-active properties of composite systems based on synthetic polyelectrolytes and non-ionic surfactants in saline medium

    Directory of Open Access Journals (Sweden)

    Kainzhamal Omarova

    2014-12-01

    Full Text Available For intensification of the imbibition process of porous systems and for displacing liquids by other liquids, particularly in secondary oil production, the polycomplexes based on synthetic polyelectrolytes and non-ionic surfactants are of interest. The surface activity of solutions of composite systems based on polyethyleneimine (PEI and ethoxylated isooctylphenol (OP-10, PEI and ethylene and propylene oxide block copolymer in pure and mineralized water at the water/air, water/oil interfaces have been studied. In comparison with pure water, a medium salinity causes the increase of solutions surface tension of the surfactants and their mixtures with PEI by 2-4 mJ/m2. The surface tension value increases weakly (by 1-4 mJ/m2 under the mineralization of water. At increased relative concentration of OP-10, ethylene and propylene oxide block copolymer, patterns of surface tension change are similar to those ones in pure water. The wetting action of salt solutions of PEI and block copolymer on the oil substrate formed on the glass plate surface was established.

  9. 3D solid supported inter-polyelectrolyte complexes obtained by the alternate deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate).

    Science.gov (United States)

    Guzmán, Eduardo; Maestro, Armando; Llamas, Sara; Álvarez-Rodríguez, Jesús; Ortega, Francisco; Maroto-Valiente, Ángel; Rubio, Ramón G

    2016-01-01

    This work addresses the formation and the internal morphology of polyelectrolyte layers obtained by the layer-by-layer method. A multimodal characterization showed the absence of stratification of the films formed by the alternate deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate). Indeed the final organization might be regarded as three-dimensional solid-supported inter-polyelectrolyte films. The growth mechanism of the multilayers, followed using a quartz crystal microbalance, evidences two different growth trends, which show a dependency on the ionic strength due to its influence onto the polymer conformation. The hydration state does not modify the multilayer growth, but it contributes to the total adsorbed mass of the film. The water associated with the polyelectrolyte films leads to their swelling and plastification. The use of X-ray photoelectron spectroscopy has allowed for deeper insights on the internal structure and composition of the polyelectrolyte multilayers. PMID:26977377

  10. 3D solid supported inter-polyelectrolyte complexes obtained by the alternate deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate)

    Science.gov (United States)

    Maestro, Armando; Llamas, Sara; Álvarez-Rodríguez, Jesús; Ortega, Francisco; Maroto-Valiente, Ángel

    2016-01-01

    Summary This work addresses the formation and the internal morphology of polyelectrolyte layers obtained by the layer-by-layer method. A multimodal characterization showed the absence of stratification of the films formed by the alternate deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate). Indeed the final organization might be regarded as three-dimensional solid-supported inter-polyelectrolyte films. The growth mechanism of the multilayers, followed using a quartz crystal microbalance, evidences two different growth trends, which show a dependency on the ionic strength due to its influence onto the polymer conformation. The hydration state does not modify the multilayer growth, but it contributes to the total adsorbed mass of the film. The water associated with the polyelectrolyte films leads to their swelling and plastification. The use of X-ray photoelectron spectroscopy has allowed for deeper insights on the internal structure and composition of the polyelectrolyte multilayers. PMID:26977377

  11. Spin-Coated Polyelectrolyte Coacervate Films.

    Science.gov (United States)

    Kelly, Kristopher D; Schlenoff, Joseph B

    2015-07-01

    Thin films of complexes made from oppositely charged polyelectrolytes have applications as supported membranes for separations, cell growth substrates, anticorrosion coatings, biocompatible coatings, and drug release media, among others. The relatively recent technique of layer-by-layer assembly reliably yields conformal coatings on substrates but is impractically slow for films with thickness greater than about 1 μm, even when accelerated many fold by spraying and/or spin assembly. In the present work, thin, uniform, smooth films of a polyelectrolyte complex (PEC) are rapidly made by spin-coating a polyelectrolyte coacervate, a strongly hydrated viscoelastic liquidlike form of PEC, on a substrate. While the apparatus used to deposit the PEC film is conventional, the behavior of the coacervate, especially the response to salt concentration, is highly nontraditional. After glassification by immersion in water, spun-on films may be released from their substrates to yield free-standing membranes of thickness in the micrometer range.

  12. Reorganization of the 3D matrix of polyelectrolytes complexes of chitosan/chondroitin sulfate swollen in different conditions of pH and immersion time

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, Andre R.; Piai, Juliana F.; Rubira, Adley F.; Muniz, Edvani C., E-mail: ecmuniz@uem.b [Universidade Estadual de Maringa (DG/UEM), PR (Brazil). Dept. de Quimica. Grupo de Materiais Polimericos e Compositos

    2009-07-01

    The chitosan (CT), a polysaccharide that has excellent properties for use as biomaterials, shows cationic nature and properties of high charge density in acidic solutions, thus CT can form complex polyelectrolyte (PEC) with polyanionic moieties such as the chondroitin sulfate (CS), a key component of cartilage matrix. We studied the reorganization of chains on 3D matrix of CT/CS PEC at swollen state in different conditions of pH and immersion time. It was verified that this PEC (QT/CS) has the capacity to reorganize its 3D matrix but it depends of the pH of the medium in which it is swelled and the time that remains immersed. The reorganization of the 3D matrix is caused by the reordering of the chains forming the PEC after the release of the CS, that occurs mainly at pH values higher than or close to the pKa of CT (pKa CT) . Such reorganization was detected by X-ray diffraction profiles and allows an increase in crystallinity, thermal stability and pore size of the PEC. This shows that the PEC produced can be processed to suit its use as bio material, applied i.e. as drugs release devices. (author)

  13. Interaction of actinide cations with synthetic polyelectrolytes

    International Nuclear Information System (INIS)

    The binding of Am+3, Th+4 and UO2+2 to polymaleic acid, polyethylenemaleic acid and polymethylvinylethermaleic acid has been measured by a solvent extraction technique at 250C and either 0.02 or 0.10 M ionic strength. The solutions were buffered over a pH range such that the percent of carboxylate groups ionized ranged from 25 to 74%. The binding was described by two constants, β1 and β2, which were evaluated after correction for complexation of the actinide cations by acetate and hydrolysis. For comparable degrees of ionization, all three polyelectrolytes showed similar binding strengths. In general, these results indicated that the binding of actinides to these synthetic polyelectrolytes is basically similar to that of natural polyelectrolytes such as humic and fulvic acids. (orig.)

  14. Molecular Dynamics Simulation for the Effect of Chain Length of Spacer and Tail of Cationic Gemini Surfactant on the Complex with Anionic Polyelectrolyte%连接基团与尾链长度对阳离子Gemini表面活性剂与阴离子聚电解质复合物影响的分子动力学模拟

    Institute of Scientific and Technical Information of China (English)

    徐毅; 冯剑; 尚亚卓; 刘洪来

    2007-01-01

    Interaction of anionic polyelectrolyte with cationic gemini surfactant has been investigated by coarse-grained molecular dynamics simulation. Polyelectrolyte facilitates the oppositely charged ionic surfactants to aggregate by suppressing the electrostatic repulsion between ionic head groups leading to the formation of micellar complex. With addition of surfactant, the conformation of polyion chain changes from stretched to random coiled to spherical, and at the same time more free micelles are formed by surfactants in mixtures. Increasing the length of spacer or tail chain in gemini surfactant will weaken its interaction with polyelectrolyte and simultaneously strengthen its tendency to self-assemble. The simulation results are consistent with experimental observations and reveal that the electrostatic interaction plays an important role in the interaction of polyelectrolyte with gemini surfactant.

  15. Diffusion of polyelectrolytes in polyelectrolyte gels

    Science.gov (United States)

    Rahalkar, Anand; Muthukumar, Murugappan

    2015-03-01

    Using dynamic light scattering, we have investigated the diffusion coefficient of sodium poly(styrene sulfonate) in a matrix of poly(acrylamide-co-acrylate) gels. The diffusion coefficient of the probe polyelectrolyte exhibits a crossover behavior from a particle-diffusion to entropic-barrier dominated diffusion, as the molecular weight is increased. The effect of electrostatics, by varying the charge density of the matrix, on probe diffusion constant will be presented.

  16. Interactions of cellulose-based comb polyelectrolyte with oppositely charged surfactant dodecyl-trimethylammonium bromide.

    Science.gov (United States)

    Pan, Hong; Chen, Pei-Yao; Liu, Hai-Xue; Chen, Yu; Wei, Yu-Ping; Zhang, Ming-Jie; Cheng, Fa

    2012-07-01

    A comb ethyl cellulose-g-sodium polyacrylate (EC-g-SPA) was synthesized by atom transfer radical polymerization. The amphiphilic properties of the EC-g-SPA were determined by surface tension measurements. The interactions between EC-g-SPA and the cationic surfactant dodecyl-trimethylammonium bromide (C12TAB) were investigated by surface tension, turbidity, dynamic light scattering and transmission electron microscopy (TEM). The results revealed that the critical aggregate concentration (CAC) of the complexes was 0.8mM. When the C12TAB concentration was lower than the CAC, the hydrodynamic diameter (Dh) of the complexes decreased as the surfactant concentration was increased. As the C12TAB concentration was increased above the CAC, the Dh initially increased slightly, followed by a sharp decrease. The changes in the sizes and shapes of the aggregates were studied by TEM. The interactions between two species and the structure of the EC-g-SPA/C12TAB complexes were also discussed. PMID:24750878

  17. Intracellular interactions of electrostatically mediated layer-by-layer assembled polyelectrolytes based sorafenib nanoparticles in oral cancer cells.

    Science.gov (United States)

    Poojari, Radhika; Kini, Sudarshan; Srivastava, Rohit; Panda, Dulal

    2016-07-01

    In this paper, we report the preparation of LbL-nanoSraf (100-300nm) comprising of layer-by-layer (LbL) assembled polyelectrolytes dextran-sulfate/poly-l-arginine, with a multikinase inhibitor sorafenib (Sraf) encapsulated calcium carbonate (CaCO3) nanoparticles for oral cancer therapy in vitro. The zeta potential of LbL-nanoSraf exhibited a negative charge of the polyanionic dextran sulfate, which alternated with a positive charge of polycationic poly-l-arginine indicating a successful LbL assembly of the two polyelectrolyte bilayers on the CaCO3 nanoparticles. The LbL-nanoSraf exhibited an encapsulation efficiency of 61±4%. The LbL-nanoSraf was characterized using field-emission gun scanning electron microscopy, X-ray powder diffraction, atomic force microscopy and confocal laser scanning microscopy. Confocal laser scanning microscopy, flow cytometry and transmission electron microscopic investigations showed the internalization of LbL-nanoSraf in human oral cancer (KB) cells. The LbL-nanoSraf exhibited more potent antiproliferative, apoptotic and antimigratory activities in KB cells than the free drug Sraf. The findings could promote the application of nano-sized LbL assembled polyelectrolytes for the delivery of Raf-kinase inhibitors and provide mechanistic insights for oral cancer therapy. PMID:26998875

  18. Dynamics of polyelectrolyte solutions under a constant gradient of base concentration

    Science.gov (United States)

    Okuzono, Tohru; Seki, Tomotaka; Toyotama, Akiko; Yamanaka, Junpei

    2015-08-01

    Phase-separation dynamics of weakly charged polyacid solutions under a constant gradient of base concentration is studied both theoretically and numerically. The time-evolution equation of polymer volume fraction is derived by assuming that the chemical equilibrium of the dissociation reaction is locally established. Numerical simulations of the system in contact with two reservoirs in which the base concentrations differ are performed. The numerical results show that the polymer volume fraction can be transported by the concentration gradient of the base, which leads to the dynamic behavior of mesophase domain structures.

  19. Structure and "surfactochromic" properties of conjugated polyelectrolyte (CPE): surfactant complexes between a cationic polythiophene and SDS in water

    OpenAIRE

    Knaapila, Matti; Evans, Rachel C.; Garamus, Vasil M.; Almásy, László; Székely, Noémi K.; Gutacker, Andrea; Scherf, Ullrich; Burrows, Hugh D.

    2011-01-01

    We report on the phase transitions, solution structure, and consequent effect on the photophysical properties of poly[3-(6-trimethylammoniumhexyl)thiophene] bromide (P3TMAHT) in aqueous sodium dodecylsulfate (SDS). Polythiophene was mixed with SDS or deuterated SDS to form P3TMAHT(SDS)x complex (x = the molar ratio of surfactant over monomer units) in D₂O and studied by small-angle neutron and X-ray scattering (SANS/SAXS) and optical spectroscopy. At room temperature, P3TMAHT forms charged ag...

  20. A highly performing electrochemiluminescent biosensor for glucose based on a polyelectrolyte-chitosan modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Dai Hong [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety (Fuzhou University) and Department of Chemistry, Fuzhou University, 523 Gongye Road, Fuzhou, Fujian 350002 (China); Wu Xiaoping [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety (Fuzhou University) and Department of Chemistry, Fuzhou University, 523 Gongye Road, Fuzhou, Fujian 350002 (China)], E-mail: wapple@fzu.edu.cn; Xu Huifeng; Wang Youmei; Chi Yuwu [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety (Fuzhou University) and Department of Chemistry, Fuzhou University, 523 Gongye Road, Fuzhou, Fujian 350002 (China); Chen Guonan [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety (Fuzhou University) and Department of Chemistry, Fuzhou University, 523 Gongye Road, Fuzhou, Fujian 350002 (China)], E-mail: gnchen@fzu.edu.cn

    2009-07-30

    A highly performing ECL glucose biosensor was developed by immobilizing glucose oxidase (GOD) onto a membrane modified glassy carbon electrode, which was prepared by using poly(diallyldimethylammonium chloride) (PDDA) doped with chitosan. In order to obtain the optimal performance of the ECL biosensor, the composition of modified membranes and a series of measurement conditions were investigated. Under the optimal conditions, this ECL biosensor was able to detect glucose in the range of 0.5-4.0 x 10{sup 4} nM with a detection limit of 0.1 nM (defined as the concentration that could be detected at the signal-to-noise ratio of 3). The relative standard deviation was 0.99% for 5 x 10{sup -8} mol/L glucose in repetitive measurements in the primary 12 potential cycles. This ECL biosensor offered the effectively improved stability of the electron transfer mediator and exhibited excellent properties for the ultrasensitive and selective determination of glucose with good reproducibility and stability. The present biosensor has also been used to determine the glucose concentrations in real serum samples. The recovery value for the assay of glucose ranged from 96.2 to 107% in the serum samples. The present biosensor displayed both specificity for glucose and retention of signal response even in a complex environment. Therefore, it provided an approach to the sensitive determination of glucose.

  1. Metallosupramolecular coordination polyelectrolytes investigated by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Metallosupramolecular coordination polyelectrolytes (MEPEs) based on rigid and flexible ditopic bis-terpyridine ligands and Fe(II) ions are investigated by Moessbauer spectroscopy. We demonstrate the influence of mechanical stress induced by grinding on the structure of MEPE as well as the ability of MEPE to self-repair through recrystallisation.

  2. Thermo-responsive hydrogels from cellulose-based polyelectrolytes and catanionic vesicles for biomedical application.

    Science.gov (United States)

    Milcovich, Gesmi; Antunes, Filipe; Golob, Samuel; Farra, Rossella; Grassi, Mario; Voinovich, Dario; Grassi, Gabriele; Asaro, Fioretta

    2016-07-01

    In this study, negatively charged catanionic vesicles/hydrophobically modified hydroxyethylcellulose polymers thermo-responsive hydrogels have been fabricated. Vesicular aggregates were found to act as multifunctional junctions for networking of modified-cellulose water solutions. The contributions of the electrostatic and hydrophobic interactions were evaluated by changing either vesicles composition or the polymer hydrophobic substitution. Thermal-induced size and lamellarity of hydrogel-enclosed vesicles were detected, with further polygonal shape changes induced by cellulose-based polymer addition. The thermal transition was also found to tune hydrogel mechanical behaviour. The network formation was further assessed through molecular insights, which allow to determine the arrangement of the polymer chains on the vesicles' surface. The examined systems exhibited interesting thermo-responsive characteristics. Thus, vesicularly cross-linked hydrogels herein presented can offer a wide variety of applications, i.e. in biomedical field, as multi-drug delivery systems, thanks to their ability to provide for different environments to guest molecules, comprising bulk water, vesicles' interior and bilayers, sites on polymeric chains. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1668-1679, 2016. PMID:26939864

  3. Development of Highly-Conductive Polyelectrolytes for Lithium Batteries

    Science.gov (United States)

    Shriver, D. F.; Ratner, M. A.; Vaynman, S.; Annan, K. O.; Snyder, J. F.

    2003-01-01

    Future NASA and Air Force missions require reliable and safe sources of energy with high specific energy and energy density that can provide thousands of charge-discharge cycles at more than 40% depth- of-discharge and that can operate at low temperatures. All solid-state batteries have substantial advantages with respect to stability, energy density, storage fife and cyclability. Among all solid-state batteries, those with flexible polymer electrolytes offer substantial advantages in cell dimensionality and commensurability, low temperature operation and thin film design. The above considerations suggest that lithium-polymer electrolyte systems are promising for high energy density batteries and should be the systems of choice for NASA and US Air Force applications. Polyelectrolytes (single ion conductors) are among most promising avenues for achieving a major breakthrough 'in the applicability of polymer- based electrolyte systems. Their major advantages include unit transference number for the cation, reduced cell polarization, minimal salt precipitation, and favorable electrolyte stability at interfaces. Our research is focused on synthesis, modeling and cell testing of single ion carriers, polyelectrolytes. During the first year of this project we attempted the synthesis of two polyelectrolytes. The synthesis of the first one, the poly(ethyleneoxide methoxy acrylateco-lithium 1,1,2-trifluorobutanesulfonate acrylate, was attempted few times and it was unsuccessful. We followed the synthetic route described by Cowie and Spence. The yield was extremely low and the final product could not be separated from the impurities. The synthesis of this polyelectrolyte is not described in this report. The second polyelectrolyte, comb polysiloxane polyelectrolyte containing oligoether and perfluoroether sidechains, was synthesized in sufficient quantity to study the range of properties such as thermal stability, Li- ion- conductivity and stability toward lithium metal. Also

  4. Conjugated polyelectrolytes fundamentals and applications

    CERN Document Server

    Liu, Bin

    2013-01-01

    This is the first monograph to specifically focus on fundamentals and applications of polyelectrolytes, a class of molecules that gained substantial interest due to their unique combination of properties. Combining both features of organic semiconductors and polyelectrolytes, they offer a broad field for fundamental research as well as applications to analytical chemistry, optical imaging, and opto-electronic devices. The initial chapters introduce readers to the synthesis, optical and electrical properties of various conjugated polyelectrolytes. This is followed by chapters on the applica

  5. Static and ultrafast optical properties of nanolayered composites. Gold nanoparticles embedded in polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Kiel, Mareike

    2012-08-16

    In the course of this thesis gold nanoparticle/polyelectrolyte multilayer structures were prepared, characterized, and investigated according to their static and ultrafast optical properties. Using the dip-coating or spin-coating layer-by-layer deposition method, gold-nanoparticle layers were embedded in a polyelectrolyte environment with high structural perfection. Typical structures exhibit four repetition units, each consisting of one gold-particle layer and ten double layers of polyelectrolyte (cationic+anionic polyelectrolyte). The structures were characterized by X-ray reflectivity measurements, which reveal Bragg peaks up to the seventh order, evidencing the high stratification of the particle layers. In the same measurements pronounced Kiessig fringes were observed, which indicate a low global roughness of the samples. Atomic force microscopy (AFM) images verified this low roughness, which results from the high smoothing capabilities of polyelectrolyte layers. This smoothing effect facilitates the fabrication of stratified nanoparticle/polyelectrolyte multilayer structures, which were nicely illustrated in a transmission electron microscopy image. The samples' optical properties were investigated by static spectroscopic measurements in the visible and UV range. The measurements revealed a frequency shift of the reflectance and of the plasmon absorption band, depending on the thickness of the polyelectrolyte layers that cover a nanoparticle layer. When the covering layer becomes thicker than the particle interaction range, the absorption spectrum becomes independent of the polymer thickness. However, the reflectance spectrum continues shifting to lower frequencies (even for large thicknesses). The range of plasmon interaction was determined to be in the order of the particle diameter for 10 nm, 20 nm, and 150 nm particles. The transient broadband complex dielectric function of a multilayer structure was determined experimentally by ultrafast pump

  6. Curvature elasticity of a grafted polyelectrolyte brush

    Science.gov (United States)

    Lei, Zhen; Miao, Bing; Yang, Shuang; Chen, Er-Qiang

    2015-06-01

    The curvature elasticity of a polyelectrolyte brush monolayer attached to curved surface is investigated theoretically. An analytical method based on the strong-stretching theory for a Gaussian chain is developed to calculate the elastic modulus induced by a polyelectrolyte brush. In particular, the scaling relations for the bending or Gaussian modulus with respect to system parameters related to the electrostatic interaction (degree of ionization and salt concentration) are derived. Using the numerical self-consistent-field theory, the inner structural, free-energy, and elastic moduli are computed for the polyelectrolyte brush with excluded-volume interactions. Compared to the analytical result, the curvature elasticity has a weaker dependence on the system parameters, which is attributed to the linearization for the Poisson-Boltzmann equation in the analytical treatment. Furthermore, our results are compared to the curvature elasticity of a bare charged surface, wherefrom the unique polyelectrolyte brush effect on the surface elasticity is clarified clearly. The scaling relations derived in our paper can serve as a guide to experimental studies on the related systems.

  7. Polyelectrolyte-based electrochemiluminescence enhancement for Ru(bpy)₃²⁺ loaded by SiO₂ nanoparticle carrier and its high sensitive immunoassay.

    Science.gov (United States)

    Ge, Zhi-Li; Song, Tian-Mei; Chen, Zhe; Guo, Wu-Run; Xie, Hong-Ping; Xie, Lian

    2015-03-01

    In this paper the strong electrochemiluminescence (ECL) nanoparticles have been prepared based on the anionic polyelectrolyte sodium polyacrylate (PAA)-ECL enhancement for Ru(bpy)3(2+), which were loaded by the carrier of SiO2 nanoparticle. There were two kinds of Ru(bpy)3(2+) for the as-prepared nanoparticles, the doped one and the exchanged one. The former was loaded inside the ECL nanoparticles by doping, in a form of ion-pair macromolecules PAA-Ru(bpy)3(2+). The corresponding ECL was enhanced about 2 times owing to the doping increase of Ru(bpy)3(2+). The latter was loaded on the PAA-doped Nafion membrane by ion exchange. The corresponding ECL was enhanced about 3 times owing to the ion-exchanging increase of Ru(bpy)3(2+). At the same time, ECL intensity of the doped-inside Ru(bpy)3(2+) was further enhanced 13 times because polyelectrolyte PAA in the doped membrane could obviously enhance electron transfer between the doped Ru(bpy)3(2+) and the working electrode. Furthermore, based on hydrophobic regions of the doped membrane antibody labeling could be easily realized by the as-prepared nanoparticles and then a high sensitive ECL immunoassay for HBsAg was developed. The linear range was between 1.0 and 100 pg mL(-1) (R(2)=0.9912). The detection limit could be as low as 0.11 pg mL(-1) (signal-to-noise ratio=3). PMID:25682425

  8. Proton binding by linear, branched, and hyperbranched polyelectrolytes

    OpenAIRE

    Koper, G.J.M.; Borkovec, M.

    2010-01-01

    This article reviews our understanding of ionization processes of weak polyelectrolytes. The emphasis is put on a general introduction to site binding models, which are able to account for many experimental features of linear and branched polyelectrolytes, including dendrimers. These models are fully compatible with the classical description of acid-base equilibria. The review further discusses the nature of the site-site interaction and role of conformational equilibria. Experimental chargin...

  9. Supramolecular Langmuir monolayers and multilayered vesicles of self-assembling DNA–lipid surface structures and their further implications in polyelectrolyte-based cell transfections

    Energy Technology Data Exchange (ETDEWEB)

    Demirsoy, Fatma Funda Kaya [Ankara University, The Central Laboratory of The Institute of Biotechnology (Turkey); Eruygur, Nuraniye [Gazi University, Department of Pharmacognosy, Faculty of Pharmacy (Turkey); Süleymanoğlu, Erhan, E-mail: erhans@mail.ru [Gazi University, Department of Pharmaceutical Chemistry, Faculty of Pharmacy (Turkey)

    2015-01-15

    The basic interfacial characteristics of DNA–lipid recognitions have been studied. The complex structures of individual unbound DNA molecules and their binary and ternary complexes with zwitterionic lipids and divalent cations were followed by employing lipid monolayers at the air–liquid interfaces, as well as by performing various microscopic, spectroscopic, and thermodynamic measurements with multilayered vesicles. The pressure-area isotherms depicted that Mg{sup 2+}-ions increase the surface pressure of lipid films and thus give rise to electrostatic and hydrophobic lipid–DNA interactions in terms of DNA adsorption, adhesion, and compaction. These features were further approached by using multilamellar vesicles with a mean diameter of 850 nm, where a metal ion-directed nucleic acid compaction and condensation effects were shown. The data obtained show the effectiveness of Langmuir monolayers and lipid multilayers in studying nucleic acid–lipid recognitions. The data provide with further details and support previous reports on mainly structural features of these recognitions. Biomolecular surface recognition events were presented in direct link with spectral and thermodynamic features of lipid vesicle–polynucleotide complex formations. The results serve to build a theoretical model considering the use of neutral lipids in lipoplex designs as a polyelectrolyte alternatives to the currently employed cytotoxic cationic liposomes. The supramolecular structures formed and their possible roles in interfacial electrostatic and hydrophobic mechanisms of endosomal escape in relevant cell transfection assays are particularly emphasized.

  10. A self-healing hydrogel formation strategy via exploiting endothermic interactions between polyelectrolytes.

    Science.gov (United States)

    Ren, Ying; Lou, Ruyun; Liu, Xiaocen; Gao, Meng; Zheng, Huizhen; Yang, Ting; Xie, Hongguo; Yu, Weiting; Ma, Xiaojun

    2016-05-01

    We report a strategy to synthesize self-healing hydrogels via exploiting endothermic interactions between polyelectrolytes. Natural polysaccharides and their derivatives were used to form reversible polyelectrolyte complexes by selecting appropriately charged chemical groups and counterions. This simple and effective method to fabricate self-healing hydrogels will find applications in diverse fields such as surface coating and 3D printing. PMID:27078585

  11. Scaling Laws of Polyelectrolyte Adsorption

    OpenAIRE

    Borukhov, I.; Andelman, D.; Orland, H.

    1997-01-01

    Adsorption of charged polymers (polyelectrolytes) from a semi-dilute solution to a charged surface is investigated theoretically. We obtain simple scaling laws for (i) the amount of polymer adsorbed to the surface, Gamma, and (ii) the width of the adsorbed layer D, as function of the fractional charge per monomer p and the salt concentration c_b. For strongly charged polyelectrolytes (p

  12. Synthesis of fluorene-based polyelectrolytes tethering different counterions for single-component white light-emitting electrochemical cells

    Science.gov (United States)

    Yang, Sheng-Hsiung; Tsai, Chia-Sheng; Liu, Bo-Cun; Su, Hai-Ching

    2013-09-01

    A series of polyfluorene (PF) electrolytes bearing Br-, BF4 -, or PF6 - counterions were synthesized and characterized. 2,1,3-benzoselenadiazole moieties were incorporated into polymer main chains to produce single-component white lightemitting polymers. The thermal stability of Br-containing ionic PF was decreased because of the Hofmann elimination occurred at higher temperature. By replacing Br- with BF4 - or PF6 - counterions, the thermal stability of polymers was significantly improved. The emission intensity around 550 nm was decreased for ionic polyelectrolytes. The optimized spin-coated light-emitting electrochemical cell (LEC) with the configuration of ITO/PEDOT/polymer/Ag showed a maximum luminescence efficiency of 1.56 lm/W at a low operation bias of 3 V. The single-component LEC device exhibited pure white light emission with CIE'1931 coordinates approaching (0.33, 0.33) and high color rendering index (CRI < 85), referring to its potential use in solid-state-lighting application.

  13. NIR photoregulated chemo- and photodynamic cancer therapy based on conjugated polyelectrolyte-drug conjugate encapsulated upconversion nanoparticles

    Science.gov (United States)

    Yuan, Youyong; Min, Yuanzeng; Hu, Qinglian; Xing, Bengang; Liu, Bin

    2014-09-01

    The design of nanoplatforms with target recognition and near-infrared (NIR) laser photoregulated chemo- and photodynamic therapy is highly desirable but remains challenging. In this work, we have developed such a system by taking advantage of a conjugated polyelectrolyte (CPE)-drug conjugate and upconversion nanoparticles (UCNPs). The poly(ethylene glycol) (PEG) grafted CPE not only serves as a polymer matrix for UCNP encapsulation, but also as a fluorescent imaging agent, a photosensitizer as well as a carrier for chemotherapeutic drug doxorubicin (DOX) through a UV-cleavable ortho-nitrobenzyl (NB) linker. Upon 980 nm laser irradiation, the UCNPs emit UV and visible light. The up-converted UV light is utilized for controlled drug release through the photocleavage of the ortho-nitrobenzyl linker, while the up-converted visible light is used to initiate the polymer photosensitizer to produce reactive oxygen species (ROS) for photodynamic therapy. The NIR photo-regulated UCNP@CPE-DOX showed high efficiency of ROS generation and controlled drug release in cancer cells upon single laser irradiation. In addition, the combination therapy showed enhanced inhibition of U87-MG cell growth as compared to sole treatments. As two light sources with different wavelengths are always needed for traditional photodynamic therapy and photoregulated drug release, the adoption of UCNPs as an NIR light switch is highly beneficial to combined chemo- and photodynamic therapy with enhanced therapeutic effects.

  14. Polyelectrolyte-based electrochemiluminescence enhancement for Ru(bpy){sub 3}{sup 2+} loaded by SiO{sub 2} nanoparticle carrier and its high sensitive immunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Zhi-Li; Song, Tian-Mei; Chen, Zhe [College of Pharmaceutical Science, Soochow University, Suzhou 215123 (China); Guo, Wu-Run [College of Pharmaceutical Science, Soochow University, Suzhou 215123 (China); College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002 (China); Xie, Hong-Ping, E-mail: hpxie@suda.edu.cn [College of Pharmaceutical Science, Soochow University, Suzhou 215123 (China); Xie, Lian, E-mail: xielian@suda.edu.cn [College of Pharmaceutical Science, Soochow University, Suzhou 215123 (China)

    2015-03-03

    Highlights: • Preparation of strong ECL nanoparticles PAA–Ru@SiO{sub 2}/[PAA⋯Ru&Nafion⋯Ru]. • Ion-pair macromolecule PAA–Ru formed to greatly increase the doping amount. • PAA&Nafion membrane increased the amount of ion-exchanged Ru(bpy){sub 3}{sup 2+}. • PAA&Nafion membrane enhanced the ability of electron transfer. • Realized antibody labeling and established a high-sensitive immunoassay. - Abstract: In this paper the strong electrochemiluminescence (ECL) nanoparticles have been prepared based on the anionic polyelectrolyte sodium polyacrylate (PAA)-ECL enhancement for Ru(bpy){sub 3}{sup 2+}, which were loaded by the carrier of SiO{sub 2} nanoparticle. There were two kinds of Ru(bpy){sub 3}{sup 2+} for the as-prepared nanoparticles, the doped one and the exchanged one. The former was loaded inside the ECL nanoparticles by doping, in a form of ion-pair macromolecules PAA–Ru(bpy){sub 3}{sup 2+}. The corresponding ECL was enhanced about 2 times owing to the doping increase of Ru(bpy){sub 3}{sup 2+}. The latter was loaded on the PAA-doped Nafion membrane by ion exchange. The corresponding ECL was enhanced about 3 times owing to the ion-exchanging increase of Ru(bpy){sub 3}{sup 2+}. At the same time, ECL intensity of the doped-inside Ru(bpy){sub 3}{sup 2+} was further enhanced 13 times because polyelectrolyte PAA in the doped membrane could obviously enhance electron transfer between the doped Ru(bpy){sub 3}{sup 2+} and the working electrode. Furthermore, based on hydrophobic regions of the doped membrane antibody labeling could be easily realized by the as-prepared nanoparticles and then a high sensitive ECL immunoassay for HBsAg was developed. The linear range was between 1.0 and 100 pg mL{sup −1} (R{sup 2} = 0.9912). The detection limit could be as low as 0.11 pg mL{sup −1} (signal-to-noise ratio = 3)

  15. Bioresorbable polyelectrolytes for smuggling drugs into cells.

    Science.gov (United States)

    Jaganathan, Sripriya

    2016-06-01

    There is ample evidence that biodegradable polyelectrolyte nanocapsules are multifunctional vehicles which can smuggle drugs into cells, and release them upon endogenous activation. A large number of endogenous stimuli have already been tested in vitro, and in vivo research is escalating. Thus, the interest in the design of intelligent polyelectrolyte multilayer (PEM) drug delivery systems is clear. The need of the hour is a systematic translation of PEM-based drug delivery systems from the lab to clinical studies. Reviews on multifarious stimuli that can trigger the release of drugs from such systems already exist. This review summarizes the available literature, with emphasis on the recent progress in PEM-based drug delivery systems that are receptive in the presence of endogenous stimuli, including enzymes, glucose, glutathione, pH, and temperature, and addresses different active and passive drug targeting strategies. Insights into the current knowledge on the diversified endogenous approaches and methodological challenges may bring inspiration to resolve issues that currently bottleneck the successful implementation of polyelectrolytes into the catalog of third-generation drug delivery systems. PMID:25961363

  16. Improving Photocatalytic Activity through Electrostatic Self-Assembly: Polyelectrolytes as Tool for Solar Energy Conversion?

    Science.gov (United States)

    Groehn, Franziska

    2015-03-01

    With regard to the world's decreasing energy resources, developing strategies to exploit solar energy become more and more important. One approach is to take advantage of photocatalysis. Inspired by natural systems such as assemblies performing photosynthesis, it is highly promising to self-assemble synthetic functional species to form more effective or tailored supramolecular units. In this contribution, a new type of photocatalytically active self-assembled nanostructures in aqueous solution will be presented: supramolecular nano-objects obtained through self-assembly of macroions and multivalent organic or inorganic counterions. Polyelectrolyte-porphyrin nanoscale assemblies exhibit up to 10-fold higher photocatalytic activity than the corresponding porphyrins without polymeric template. Other self-assembled catalysts based on polyelectrolytes can exhibit expressed selectivity in a photocatalytic model reaction or even allow catalytic reactions in solution that are not possible with the building blocks only. Further, current results on combining different functional units at the polyelectrolyte template represent a next step towards more complex supramolecular structures for solar energy conversion.

  17. Aggregation dynamics of rigid polyelectrolytes

    Science.gov (United States)

    Tom, Anvy Moly; Rajesh, R.; Vemparala, Satyavani

    2016-01-01

    Similarly charged polyelectrolytes are known to attract each other and aggregate into bundles when the charge density of the polymers exceeds a critical value that depends on the valency of the counterions. The dynamics of aggregation of such rigid polyelectrolytes are studied using large scale molecular dynamics simulations. We find that the morphology of the aggregates depends on the value of the charge density of the polymers. For values close to the critical value, the shape of the aggregates is cylindrical with height equal to the length of a single polyelectrolyte chain. However, for larger values of charge, the linear extent of the aggregates increases as more and more polymers aggregate. In both the cases, we show that the number of aggregates decrease with time as power laws with exponents that are not numerically distinguishable from each other and are independent of charge density of the polymers, valency of the counterions, density, and length of the polyelectrolyte chain. We model the aggregation dynamics using the Smoluchowski coagulation equation with kernels determined from the molecular dynamics simulations and justify the numerically obtained value of the exponent. Our results suggest that once counterions condense, effective interactions between polyelectrolyte chains short-ranged and the aggregation of polyelectrolytes are diffusion-limited.

  18. Poor-solvent polyelectrolytes

    International Nuclear Information System (INIS)

    Using extensive molecular dynamics simulations we study the behaviour of polyelectrolytes (PEs) in poor solvents, explicitly taking the counterions into account. The resulting pearl-necklace structures are subject to strong conformational fluctuations. These lead to small signatures in the form factor and the force-extension relation, which is a severe obstacle to experimental observations. In addition, we study how the necklace collapses as a function of the Bjerrum length. Finally, we demonstrate that the position of the first peak in the inter-chain structure factor varies with the monomer density as ∼ ρm0.35 for all densities, which shows a pertinent different behaviour as compared to that of PE solutions in good solvent

  19. Ion transport through electrolyte/polyelectrolyte multi-layers

    Science.gov (United States)

    Femmer, Robert; Mani, Ali; Wessling, Matthias

    2015-06-01

    Ion transport of multi-ionic solutions through layered electrolyte and polyelectrolyte structures are relevant in a large variety of technical systems such as micro and nanofluidic devices, sensors, batteries and large desalination process systems. We report a new direct numerical simulation model coined EnPEn: it allows to solve a set of first principle equations to predict for multiple ions their concentration and electrical potential profiles in electro-chemically complex architectures of n layered electrolytes E and n polyelectrolytes PE. EnPEn can robustly capture ion transport in sub-millimeter architectures with submicron polyelectrolyte layers. We proof the strength of EnPEn for three yet unsolved architectures: (a) selective Na over Ca transport in surface modified ion selective membranes, (b) ion transport and water splitting in bipolar membranes and (c) transport of weak electrolytes.

  20. Specific counterion repercussions on the thermal, pH-response, and electrochemical properties of side-chain leucine based chiral polyelectrolytes.

    Science.gov (United States)

    Narayanan, Amal; Bauri, Kamal; Ruidas, Bhuban; Pradhan, Goutam; Banerjee, Sanjib; De, Priyadarsi

    2014-11-11

    Effects of counterions of side chain amino acid based polyelectrolytes (PEs) on the solubility in aqueous medium, pH responsiveness, thermal properties, and ionic conductivities have been appraised. Deprotection of the tert-butyl carbamate (Boc) group from poly(Boc-l-leucine methacryloyloxyethyl ester) [P(Boc-l-Leu-HEMA)] was carried out to produce PE with trifluoroacetate as an associative counteranion (1a). PEs with bis(trifluoromethylsulfonyl)imide and hexafluorophosphate counteranion were prepared through anion exchange reactions of 1a. Protonation of the neutralized polymer (2) obtained from 1a, followed by anion exchange, leads to the production of miscellaneous PEs bearing different counteranions, such as tetrafluoroborate, trifluoromethanesulfonate, chloride, and nitrate. Differential scanning calorimetry traces of the PEs reveal that the comparatively larger and weakly coordinated counteranions require less thermal energy to dissociate, and thus, the glass transition temperature (Tg) of the PEs fall off with an increase in the size of the counteranion. A remarkable conductivity of 2.1 mS/cm was obtained in deionized water when Cl(-) acted as the counteranion. Steric and electronic factors of the counteranion induce a change of transition pH in different PEs, although the chiroptical nature was retained, as confirmed by circular dichroism spectroscopy. PMID:25333268

  1. Fabrication of polyelectrolyte multilayered nano-capsules using a continuous layer-by-layer approach.

    Science.gov (United States)

    Elizarova, Iuliia S; Luckham, Paul F

    2016-05-15

    The layer-by-layer approach is a highly versatile method for the fabrication of multilayered polymeric films and capsules. It has been widely investigated in research for various polyelectrolyte pairs and core template particles. However, the fabrication of nano-sized capsules at the larger scale is difficult and time consuming, due to the necessity of washing and centrifugation steps before the deposition of each polyelectrolyte layer. This results not only in a very long fabrication time, but also in the partial loss of particles during those intermediate steps. In this study, we introduced a continuous approach for the fabrication of multilayer polyelectrolyte based nano-capsules using calcium phosphate core nanoparticles and a tubular flow type reactor with the potential for synthesizing tens of milligrams of capsules per hour. Adsorption of the polyelectrolyte layer occurred in the tubing where particles and polyelectrolyte solution of choice were mixed, creating a layer of polyelectrolyte on the particles. After this, these newly surfaced-modified particles passed into the next segment of tubing, where they were mixed with a second polyelectrolyte of opposite charge. This process can be continuously repeated until the desired number of layers is achieved. One potential problem with this method concerned the presence of any excess polyelectrolyte in the tubing, so careful control of the amount of polymer added was crucial. It was found that slightly under dosing the amount of added polyelectrolyte ensured that negligible unadsorbed polyelectrolyte remained in solution. The particles created at each deposition step were stable, as they all had a zeta potential of greater than ±25mV. Furthermore the zeta potential measurements showed that charge reversal occurred at each stage. Having achieved the necessary number of polyelectrolyte layers, the calcium phosphate cores were easily removed via dissolution in either hydrochloric or acetic acid. PMID:26939072

  2. Ion binding by humic and fulvic acids: A computational procedure based on functional site heterogeneity and the physical chemistry of polyelectrolyte solutions

    International Nuclear Information System (INIS)

    Ion binding equilibria for humic and fulvic acids are examined from the point of view of functional site heterogeneity and the physical chemistry of polyelectrolyte solutions. A detailed explanation of the potentiometric properties of synthetic polyelectrolytes and ion-exchange gels is presented first to provide the basis for a parallel consideration of the potentiometric properties exhibited by humic and fulvic acids. The treatment is then extended to account for functional site heterogeneity. Sample results are presented for analysis of the ion-binding reactions of a standard soil fulvic acid (Armadale Horizons Bh) with this approach to test its capability for anticipation of metal ion removal from solution. The ultimate refined model is shown to be adaptable, after appropriate consideration of the heterogeneity and polyelectrolyte factors, to programming already available for the consideration of ion binding by inorganics in natural waters. (orig.)

  3. Donor Schiff Base Polymeric Complexes

    Directory of Open Access Journals (Sweden)

    Shubhangi N. Kotkar

    2013-01-01

    Full Text Available A series of new polymeric complexes of Mn(II, Co(II, Ni(II, Cu(II, and Zn(II were prepared with a Schiff base ligand derived from condensation of 2,4-dihydroxy acetophenone and p-phenylene diamine and characterized by elemental analysis and IR and NMR spectral data. The antimicrobial activity of the Schiff base and its polymeric complexes have been studied.

  4. Dynamic Ordering Transitions of Liquid Crystals Driven by Interfacial Complexes Formed Between Polyanions and Amphiphilic Polyamines

    OpenAIRE

    Kinsinger, Michael I.; Buck, Maren E.; de Campos, Fernando; Lynn, David M.; Abbott, Nicholas L.

    2008-01-01

    We report the design of an amphiphilic polyamine based on poly(2-alkenyl azlactone) (polymer 1) that strongly couples the formation of polyelectrolyte complexes at aqueous/liquid crystal (LC) interfaces to ordering transitions in the LC. We demonstrate that the addition of a strong anionic polyelectrolyte to aqueous solutions in contact with polymer 1-laden LC interfaces (prepared by Langmuir-Schaefer transfer of monolayers of polymer 1 onto micrometer-thick films of nematic LC) triggers orde...

  5. Polyelectrolyte (PE) induced interactions between Charged and zwitterionic Colloids

    Science.gov (United States)

    Pryamitsyn, Victor; Ganesan, Venkat

    2014-03-01

    A numerical self-consistent field (SCF) theory approach was developed for studying mixture of polyelectrolytes with charged and uncharged nanoparticles. Such an approach was used to analyze within the mean-field limit the polyelectrolyte-mediated effective interactions between the particles. The system considered allows for the local PE and particle charges to be defined by the local concentration of ionizable on groups on the particles and polyelectrolytes, ambient conditions like pH and the local electrostatic potential. Calculation of the free energy of a system of one, two and three particles in the polyelectrolyte solution allowdd us to calculate the particle insertion free energy, two and three body particle-particle interactions as a function of the properties of solution, polymer-particle interactions and the particle size. For the situation involving acidic PE and a base type positively charged particles, the PE mediated particle-particle interaction is purely repulsive for the larger particle-particle distances at low polymer concentrations. At short-particle particle distances and/or higher polyelectrolyte concentrations the particle-particle interaction becomes a depletion-type attraction. For Zwitterionic positively chaged paticles particles we have found a a range

  6. Water Dispersible and Biocompatible Porphyrin-Based Nanospheres for Biophotonics Applications: A Novel Surfactant and Polyelectrolyte-Based Fabrication Strategy for Modifying Hydrophobic Porphyrins.

    Science.gov (United States)

    Sheng, Ning; Zong, Shenfei; Cao, Wei; Jiang, Jianzhuang; Wang, Zhuyuan; Cui, Yiping

    2015-09-01

    The hydrophobility of most porphyrin and porphyrin derivatives has limited their applications in medicine and biology. Herein, we developed a novel and general strategy for the design of porphyrin nanospheres with good biocompatibility and water dispersibility for biological applications using hydrophobic porphyrins. In order to display the generality of the method, we used two hydrophobic porphyrin isomers as starting material which have different structures confirmed by an X-ray technique. The porphyrin nanospheres were fabricated through two main steps. First, the uniform porphyrin nanospheres stabilized by surfactant were prepared by an interfacially driven microemulsion method, and then the layer-by-layer method was used for the synthesis of polyelectrolyte-coated porphyrin nanospheres to reduce the toxicity of the surfactant as well as improve the biocompatibility of the nanospheres. The newly fabricated porphyrin nanospheres were characterized by TEM techniques, the electronic absorption spectra, photoluminescence emission spectra, dynamic light scattering, and cytotoxicity examination. The resulting nanospheres demonstrated good biocompatibility, excellent water dispersibility and low toxicity. In order to show their application in biophotonics, these porphyrin nanospheres were successfully applied in targeted living cancer cell imaging. The results showed an effective method had been explored to prepare water dispersible and highly stable porphyrin nanomaterial for biophotonics applications using hydrophobic porphyrin. The approach we reported shows obvious flexibility because the surfactants and polyelectrolytes can be optionally selected in accordance with the characteristics of the hydrophobic material. This strategy will expand the applications of hydrophobic porphyrins owning excellent properties in medicine and biology.

  7. Accumulation of small protein molecules in a macroscopic complex coacervate

    NARCIS (Netherlands)

    Lindhoud, S.; Claessens, M.M.A.E.

    2016-01-01

    To obtain insight into the accumulation of proteins into macroscopic complex coacervate phases, the lysozyme concentration in complex coacervates containing the cationic polyelectrolyte poly-(N,N dimethylaminoethyl methacrylate) and the anionic polyelectrolyte polyacrylic acid was investigated as a

  8. Biological and Biomimetic Comb Polyelectrolytes

    Directory of Open Access Journals (Sweden)

    Aristeidis Papagiannopoulos

    2010-05-01

    Full Text Available Some new phenomena involved in the physical properties of comb polyelectrolyte solutions are reviewed. Special emphasis is given to synthetic biomimetic materials, and the structures formed by these molecules are compared with those of naturally occurring glycoprotein and proteoglycan solutions. Developments in the determination of the structure and dynamics (viscoelasticity of comb polymers in solution are also covered. Specifically the appearance of multi-globular structures, helical instabilities, liquid crystalline phases, and the self-assembly of the materials to produce hierarchical comb morphologies is examined. Comb polyelectrolytes are surface active and a short review is made of some recent experiments in this area that relate to their morphology when suspended in solution. We hope to emphasize the wide variety of phenomena demonstrated by the vast range of naturally occurring comb polyelectrolytes and the challenges presented to synthetic chemists designing biomimetic materials.

  9. Multilayered polyelectrolyte microcapsules: interaction with the enzyme cytochrome C oxidase.

    Directory of Open Access Journals (Sweden)

    Laura Pastorino

    Full Text Available Cell-sized polyelectrolyte capsules functionalized with a redox-driven proton pump protein were assembled for the first time. The interaction of polyelectrolyte microcapsules, fabricated by electrostatic layer-by-layer assembly, with cytochrome c oxidase molecules was investigated. We found that the cytochrome c oxidase retained its functionality, that the functionalized microcapsules interacting with cytochrome c oxidase were permeable and that the permeability characteristics of the microcapsule shell depend on the shell components. This work provides a significant input towards the fabrication of an integrated device made of biological components and based on specific biomolecular functions and properties.

  10. CONJUGATED POLYMERS AND POLYELECTROLYTES IN SOLAR PHOTOCONVERSION, Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Schanze, Kirk S [University of Florida

    2014-08-05

    This DOE-supported program investigated the fundamental properties of conjugated polyelectrolytes, with emphasis placed on studies of excited state energy transport, self-assembly into conjugated polyelectroyte (CPE) based films and colloids, and exciton transport and charge injection in CPE films constructed atop wide bandgap semiconductors. In the most recent grant period we have also extended efforts to examine the properties of low-bandgap donor-acceptor conjugated polyelectrolytes that feature strong visible light absorption and the ability to adsorb to metal-oxide interfaces.

  11. Self-Assembly of Polyoxometalate and Polyelectrolyte Macroions into Mechanically Strong Supramolecular Hydrogels

    Science.gov (United States)

    Jing, Benxin; Zhu, Y. Elaine

    Polyoxometalate (POM) macroions are the nanoclusters of transition metal oxide with size 1-10 nm and well-defined structure at the atom level. Because of their stoichiometric surface groups and high solubility in polar solvents to form thermodynamically stable solution, POMs are studied as excellent model macroions at nanoscale. In this work, we explore the electrostatic controlled self-assembly of anionic POMs and cationic or zwitterionic polyelectrolytes (PEs) in aqueous solution. Specifically we examine the complex formation of zwitterionic poly (3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide) (PSBMA) and cationic poly(diallyldimethylammonium chloride) (PDADMAC) with tungstate based POMs of varied valence. The phase diagram of POM/polyelectrolyte complexes is determined with varied POM/PE charge ratios. It is interesting to observe the coacervation of POMs with PSBMA. With cationic PDADMAC, hybrid POM-PDADMAC hydrogels can be formed. Nevertheless, POM-PDADMAC complexes exhibit much enhanced mechanical properties in comparison to polymer hydrogel. The viscoelastic properties of hybrid macroion complexes strongly depend on PDADMAC concentration, POM-to-PDADMAC molar ratio, the size and valence of POMs. At the intermediate range of POM-to-PDADMAC concentration ratio, shear thickening and strain hardening are observed with soft supramolecular hydrogels, which is resulted from the non-Gaussian stretching of polymer chains.

  12. Macrojunctions ordering in polyelectrolyte hydrogels

    Science.gov (United States)

    Török, Gy; Lebedev, V. T.; Cser, L.; Buyanov, A. L.; Revelskaya, L. G.

    2000-03-01

    We studied the structure of polyelectrolyte hydrogels of sodium polyacrylate cross-linked by macromolecular allyldextran (supergels). Using high-resolution SANS we have found the specific ordering of macrojunctions (structure's period ∼130 nm) that may be reliable for the network's anomaly swelling.

  13. Building Highly Flexible Polyelectrolyte Nanotubes

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ Flexibility of polyelectrolyte nanotubes is necessary if they are to be exploited in applications such as developing photoelectric devices with strong mechanical properties. In a recent attempt, high flexibility has been observed from such nanotubes prepared by a research team headed by Prof. Li Junbai of the CAS Institute of Chemistry (ICCAS).

  14. Polyelectrolytes Ability in Reducing Atrazine Concentration in Water: Surface Effects

    NARCIS (Netherlands)

    Mohd Amin, M.F.; Heijman, S.G.J.; Lopes, S.I.C.; Rietveld, L.C.

    2014-01-01

    This paper reports on the direct ability of two positively charged organic polyelectrolytes (natural-based and synthetic) to reduce the atrazine concentration in water. The adsorption study was set up using multiple glass vessels with different polymer dosing levels followed by ultrafiltration with

  15. Organic and Inorganic Dyes in Polyelectrolyte Multilayer Films

    Directory of Open Access Journals (Sweden)

    Vincent Ball

    2012-12-01

    Full Text Available Polyelectrolyte multilayer films are a versatile functionalization method of surfaces and rely on the alternated adsorption of oppositely charged species. Among such species, charged dyes can also be alternated with oppositely charged polymers, which is challenging from a fundamental point of view, because polyelectrolytes require a minimal number of charges, whereas even monovalent dyes can be incorporated during the alternated adsorption process. We will not only focus on organic dyes but also on their inorganic counterparts and on metal complexes. Such films offer plenty of possible applications in dye sensitized solar cells. In addition, dyes are massively used in the textile industry and in histology to stain textile fibers or tissues. However, the excess of non bound dyes poses serious environmental problems. It is hence of the highest interest to design materials able to adsorb such dyes in an almost irreversible manner. Polyelectrolyte multilayer films, owing to their ion exchange behavior can be useful for such a task allowing for impressive overconcentration of dyes with respect to the dye in solution. The actual state of knowledge of the interactions between charged dyes and adsorbed polyelectrolytes is the focus of this review article.

  16. Plasma-based surface modifications of polyester fabrics and their interaction with cationic polyelectrolytes and anionic dyes

    OpenAIRE

    Salem, Tarek Sayed Mohamed

    2012-01-01

    Plasma-based surface modifications offer many interesting possibilities for the production of high value-added polymeric materials. In this work, different plasma-based synthetic concepts were employed to endow poly(ethylene terephthalate) (PET) fabrics with accessible amine functionalities. These concepts were compared to find out the appropriate engineering methods, which can be further accepted by textile industries to overcome the limited reactivity of PET fabric surfaces, while the bulk ...

  17. BINDING OF IONIC SURFACTANTS ON OPPOSITELY CHARGED POLYELECTROLYTES OBSERVED BY FLUORESCENCE METHODS

    Institute of Scientific and Technical Information of China (English)

    Zhen Tong; Chao-yang Wang; Bi-ye Ren; Xin-xing Liu; Fang Zeng

    2003-01-01

    Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observed with fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB),dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C12E8) were allowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalene labeled copolymers. The relative excimer emission intensity IE/IM of a cationic probe 1-pyrenemethylamine hydrochloride were chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescence results, nonionic surfactant C12E8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted the micelle formation for C12E8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyl labeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymersurfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.

  18. Field-Theoretic Studies of Nanostructured Triblock Polyelectrolyte Gels

    Science.gov (United States)

    Audus, Debra; Fredrickson, Glenn

    2012-02-01

    Recently, experimentalists have developed nanostructured, reversible gels formed from triblock polyelectrolytes (Hunt et al. 2011, Lemmers et al. 2010, 2011). These gels have fascinating and tunable properties that reflect a heterogeneous morphology with domains on the order of tens of nanometers. The complex coacervate domains, aggregated oppositely charged end-blocks, are embedded in a continuous aqueous matrix and are bridged by uncharged, hydrophilic polymer mid-blocks. We report on simulation studies that employ statistical field theory models of triblock polyelectrolytes, and we explore the equilibrium self-assembly of these remarkable systems. As the charge complexation responsible for the formation of coacervate domains is driven by electrostatic correlations, we have found it necessary to pursue full ``field-theoretic simulations'' of the models, as opposed to the familiar self-consistent field theory approach. Our investigations have focused on morphological trends with mid- and end-block lengths, polymer concentration, salt concentration and charge density.

  19. Investigation of complexing ability of ionites with various groups to some heavy and transition metal ions

    OpenAIRE

    Yedil Yergozhin; B. Taussarova; R. Ashkeyeva; L. Tugelbayeva

    2013-01-01

    The physico-chemical and complexing properties of the sorbent based on chloromethylated styrene and divinylbenzene copolymer with nicotinamide groups and copolymers based on metacryloilaminobenzene acids with 2-methyl-5-vinylpyridineisomers are studied. By potentiometric titration method the constant of polyelectrolytes functional groups ionization, the composition and strength of the resulting complexes with ions of some heavy and transition metals are determined.

  20. Formation of redox-active self-assembled polyelectrolyte-surfactant complexes integrating glucose oxidase on electrodes: Influence of the self-assembly solvent on the signal generation.

    Science.gov (United States)

    Cortez, M Lorena; Ceolín, Marcelo; Azzaroni, Omar; Battaglini, Fernando

    2015-10-01

    In this work the effects of the self-assembly solvent on the structure and electrochemical behavior of redox-active polyelectrolyte–surfactant complexes cast on electrode supports from aqueous and DMF solutions are presented. The complex studied is formed by complexation of osmium complex-modified polyallylamine (OsPA) with dodecyl sulfate (DS) surfactants. The structure of the films was characterized by GISAXS, showing that films present a lamellar mesostructure. However, when they are exposed to humid environments, films cast from aqueous solutions (OsPA–DSaq) undergo a structural transition that ultimately leads to the disappearance of the mesostructural order. On the other hand, OsPA–DS films cast from DMF solutions (OsPA–DSorg) revealed no significant changes upon exposure to humid environments. Both types of films were exposed to glucose oxidase (GOx), showing similar adsorption characteristics. Notwithstanding these similarities in GOx and content, OsPA–DSaq films revealed a more sensitive bioelectrocatalytical response to glucose as compared to OsPA–DSorg films. PMID:26094060

  1. A small-angle X-ray scattering study of complexes formed in mixtures of a cationic polyelectrolyte and an anionic surfactant

    DEFF Research Database (Denmark)

    Bergström, M.; Kjellin, U.R.M.; Claesson, P.M.;

    2002-01-01

    from a=47.7 Angstrom (MAPTAC, 100% charge density) to 58.5 Angstrom (AM-MAPTAC, 30% charge density). The unit cell length in the lamellar SDS/PVAm complex (a=36.1 Angstrom) is significantly smaller than for the different hexagonal structures. It is conjectured that the cylinders in the hexagonal...

  2. Amphiphile Adsorption on Rigid Polyelectrolytes

    OpenAIRE

    Kuhn, Paulo S.; Levin, Yan; Barbosa, Marcia C.; Ravazzolo, Ana Paula

    2007-01-01

    A theory is presented which quantitatively accounts for the cooperative adsorption of cationic surfactants to anionic polyelectrolytes. For high salt concentration we find that the critical adsorption concentration (CAC) is a bilinear function of the polyion monomer and salt concentrations, with the coefficients dependent only on the type of surfactant used. The results presented in the paper might be useful for designing more efficient gene delivery systems.

  3. Conductivity study of solid polyelectrolytes based on hydroiodide salt of poly(4-vinyl pyridine-co-butylmethacrylate), poly(4-vinyl pyridine-co-butylacrylate)

    Indian Academy of Sciences (India)

    Samadrita Goswami; Aradhana Dutta

    2013-08-01

    The chain flexibility of poly(4-vinylpyridine) was tried to increase by lowering its glass transition temperature (g) and by increasing its amorphous region by copolymerizing with butyl methacrylate and butylacrylate which act as internal plasticizer. The copolymers were prepared in five different feed molar ratios to optimize the required properties such as higher room temperature conductivity and better film-forming capacity. The conductivity and conduction behaviour of the copolymers, as well as their hydroiodide salts have been reported. There was about 103–104-fold increase in room temperature conductivity of these plasticized polyelectrolytes.

  4. On the difference in ionization properties between planar interfaces and linear polyelectrolytes

    OpenAIRE

    Borkovec, Michal; Daicic, John; Koper, Ger J. M.

    1997-01-01

    Ionizable planar interfaces and linear polyelectrolytes show markedly different proton-binding behavior. Planar interfaces protonate in a single broad step, whereas polyelectrolytes mostly undergo a two-step protonation. Such contrasting behavior is explained using a discrete-charge Ising model. This model is based on an approximation of the ionizable groups by point charges that are treated within a linearized Poisson–Boltzmann approximation. The underlying reason as ...

  5. Shell formation in short like-charged polyelectrolytes in a harmonic trap

    OpenAIRE

    Dutta, Sandipan; Jho, Y. S.

    2015-01-01

    Inspired by recent experiments and simulations on pattern formation in biomolecules by optical tweezers, a theoretical description based on reference interaction site model (RISM) integral equation method is developed to calculate the equilibrium density profiles of small polyelectrolytes in an external potential. The formalism is applied to the specific case of a finite number of polyelectrolytes trapped in a harmonic potential. The density profiles of flexible Gaussian and rigid rod-like po...

  6. Shell formation in short like-charged polyelectrolytes in a harmonic trap

    Science.gov (United States)

    Dutta, Sandipan; Jho, Y. S.

    2016-01-01

    Inspired by recent experiments and simulations on pattern formation in biomolecules by optical tweezers, a theoretical description based on the reference interaction site model (RISM) is developed to calculate the equilibrium density profiles of small polyelectrolytes in an external potential. The formalism is applied to the specific case of a finite number of Gaussian and rodlike polyelectrolytes trapped in a harmonic potential. The density profiles of the polyelectrolytes are studied over a range of lengths and numbers of polyelectrolytes in the trap, and the strength of the trap potential. For smaller polymers we recover the results for point charges. In the mean field limit the longer polymers, unlike point charges, form a shell at the boundary layer. When the interpolymer correlations are included, the density profiles of the polymers show sharp shells even at weaker trap strengths. The implications of these results are discussed.

  7. Guided wave sensing of polyelectrolyte multilayers

    DEFF Research Database (Denmark)

    Horvath, R.; Pedersen, H.C.; Cuisinier, F.J.G.

    2006-01-01

    A planar optical waveguide configuration is proposed to monitor the buildup of thick polyelectrolyte multilayers on the surface of the waveguide in aqueous solutions. Instead of detecting the layer by the electromagnetic evanescent field the polyelectrolyte layer acts as an additional waveguiding...

  8. Fibrillar films obtained from sodium soap fibers and polyelectrolyte multilayers.

    Science.gov (United States)

    Zawko, Scott A; Schmidt, Christine E

    2011-08-01

    An objective of tissue engineering is to create synthetic polymer scaffolds with a fibrillar microstructure similar to the extracellular matrix. Here, we present a novel method for creating polymer fibers using the layer-by-layer method and sacrificial templates composed of sodium soap fibers. Soap fibers were prepared from neutralized fatty acids using a sodium chloride crystal dissolution method. Polyelectrolyte multilayers (PEMs) of polystyrene sulfonate and polyallylamine hydrochloride were deposited onto the soap fibers, crosslinked with glutaraldehyde, and then the soap fibers were leached with warm water and ethanol. The morphology of the resulting PEM structures was a dense network of fibers surrounded by a nonfibrillar matrix. Microscopy revealed that the PEM fibers were solid structures, presumably composed of polyelectrolytes complexed with residual fatty acids. These fibrillar PEM films were found to support the attachment of human dermal fibroblasts.

  9. Cathodic electrodeposition of cobalt oxide films using polyelectrolytes

    International Nuclear Information System (INIS)

    Composite films consisting of cobalt hydroxide and polyelectrolytes, such as poly(diallyldimethylammonium chloride) (PDDA) and polyethylenimine (PEI), were obtained by electrodeposition. In the proposed method, electrophoretic deposition of PDDA macromolecules or PEI-Co2+ complexes has been combined with cathodic electrosynthesis of cobalt hydroxide. By varying the concentration of the polyelectrolytes in solutions, the deposition time and the current density, the amount of deposited material and its composition can be varied. The composite deposits have been studied by scanning, transmission and atomic force microscopy, X-ray diffraction and thermogravimetric analysis. The obtained results have been compared with the results of investigation of pure cobalt hydroxide films. Heat treatment of the deposits resulted in decomposition of the hydroxide precursor and burning out of polymer to form cobalt oxide films. This method enables the formation of thick nanostructured oxide films

  10. Flexible polyelectrolyte conformation in the presence of cationic and anionic surfactants

    Science.gov (United States)

    Passos, C. B.; Kuhn, P. S.; Diehl, A.

    2015-11-01

    In this work we have studied the conformation of flexible polyelectrolyte chains in the presence of cationic and anionic surfactant molecules. We developed a simple theoretical model for the formation of the polyelectrolyte-cationic surfactant complexes and mixed micelles formed by cationic and anionic surfactant molecules, in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, with the hydrophobic interaction included explicitly as an effective short-ranged attraction between the surfactant hydrocarbon tails. This simple model allows us to calculate the extension of the polyelectrolyte-cationic surfactant complexes as a function of the anionic surfactant concentration, for different types of cationic and anionic surfactant molecules. A discrete conformational transition from a collapsed state to an elongated coil was found, for all surfactant chain lengths we have considered, in agreement with the experimental observations for the unfolding of ​DNA-cationic surfactant complexes.

  11. Complexity measurement based on information theory and kolmogorov complexity.

    Science.gov (United States)

    Lui, Leong Ting; Terrazas, Germán; Zenil, Hector; Alexander, Cameron; Krasnogor, Natalio

    2015-01-01

    In the past decades many definitions of complexity have been proposed. Most of these definitions are based either on Shannon's information theory or on Kolmogorov complexity; these two are often compared, but very few studies integrate the two ideas. In this article we introduce a new measure of complexity that builds on both of these theories. As a demonstration of the concept, the technique is applied to elementary cellular automata and simulations of the self-organization of porphyrin molecules.

  12. Mechanical properties of polyelectrolyte multilayer microcapsules

    International Nuclear Information System (INIS)

    Polyelectrolyte multilayer microcapsules were recently suggested as a new type of nanoengineered microstructures and are potentially important in many areas of science and technology. The present review focuses on the mechanics of these microstructures, emphasizing novel experimental approaches and the main experimental observations. Methods based on confocal and atomic force microscopy-osmotic buckling, osmotic swelling, and compression experiments-are detailed. Also covered is the preparation of multilayer microcapsules and various encapsulation techniques. A discussion of the theoretical models suggested is given. Special emphasis is given to the analysis of experimental data. This covers regimes of deformations, the roles of elasticity and permeability in determining the capsule stiffness, the effects of ageing, molecular weight, pH, salt concentration, and organic solvent on the multilayer shell properties, a contribution from encapsulated (charged and neutral) polymers, and more. (topical review)

  13. Preparation and Evaluation of Diclofenac Sodium Tablet Coated with Polyelectrolyte Multilayer Film Using Hypromellose Acetate Succinate and Polymethacrylates for pH-Dependent, Modified Release Drug Delivery.

    Science.gov (United States)

    Jeganathan, Balamurugan; Prakya, Vijayalakshmi; Deshmukh, Abhijit

    2016-06-01

    Polyelectrolyte multilayer (PEM) film formed due to the electrostatic interaction between oppositely charged polyelectrolytes is of considerable interest because of their potential applications as both drug carriers and surface-modifying agents. In this study, in vitro studies were carried out on polyelectrolyte complexes formulated with Eudragit E (EE) and hypromellose acetate succinate (HPMCAS). The complexes of EE and HPMCAS were formulated by non-stoichiometric method. The prepared IPCs were investigated using Fourier transform infrared spectroscopy. Diclofenac sodium (DS) tablets were prepared and were coated with polymer solution of HPMCAS and EE to achieve pH-dependent and sustained-release tablets. Tablets were evaluated for their physical characteristics and in vitro drug release. The results of pharmacokinetic studies in rabbits showed that the selected formulation (F6) exhibited a delayed peak plasma concentration and marked sustained-release effect of drug in the in vivo drug release in comparison with marketed tablet. The suitable combination of PEM film based on EE and HPMCAS demonstrated potential candidate for targeted release of DS in the lower part of the gastrointestinal (GI) tract. PMID:26283195

  14. A comparison of f-element dissociation kinetics from synthetic polyelectrolytes and humic acid

    International Nuclear Information System (INIS)

    Due to their large complexing capacities, natural humic substances have been proposed as scavengers of toxic metals in aquatic systems. We studied f-element dissociation rates from naturally occurring and well characterized synthetic polyelectrolytes as a function of ph, aging time of the metal complex, and polyacid molecular weight

  15. Microgel-based engineered nanostructures and their applicability with template-directed layer-by-layer polyelectrolyte assembly in protein encapsulation.

    Science.gov (United States)

    Shenoy, Dinesh B; Sukhorukov, Gleb B

    2005-05-23

    A novel strategy for the fabrication of microcapsules is elaborated by employing biomacromolecules and a dissolvable template. Calcium carbonate (CaCO(3)) microparticles were used as sacrificial templates for the two-step deposition of polyelectrolyte coatings by surface controlled precipitation (SCP) followed by the layer-by-layer (LbL) adsorption technique to form capsule shells. When sodium alginate was used for inner shell assembly, template decomposition with an acid resulted in simultaneous formation of microgel-like structures due to calcium ion-induced gelation. An extraction of the calcium after further LbL treatment resulted in microcapsules filled with the biopolymer. The hollow as well as the polymer-filled polyelectrolyte capsules were characterized using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), and scanning force microscopy (SFM). The results demonstrated multiple functionalities of the CaCO(3) core - as supporting template, porous core for increased polymer accommodation/immobilization, and as a source of shell-hardening material. The LbL treatment of the core-inner shell assembly resulted in further surface stabilization of the capsule wall and supplementation of a nanostructured diffusion barrier for encapsulated material. The polymer forming the inner shell governs the chemistry of the capsule interior and could be engineered to obtain a matrix for protein/drug encapsulation or immobilization. The outer shell could be used to precisely tune the properties of the capsule wall and exterior. [Diagram: see text] Confocal laser scanning microscopy (CLSM) image of microcapsules (insert is after treating with rhodamine 6G to stain the capsule wall).

  16. Polyelectrolytes Ability in Reducing Atrazine Concentration in Water: Surface Effects

    OpenAIRE

    2014-01-01

    This paper reports on the direct ability of two positively charged organic polyelectrolytes (natural-based and synthetic) to reduce the atrazine concentration in water. The adsorption study was set up using multiple glass vessels with different polymer dosing levels followed by ultrafiltration with a 1 kDa membrane. The addition of polymers exhibited a capability in reducing the atrazine concentration up to a maximum of 60% in surface-to-volume ratio experiments. In the beginning, the theoret...

  17. Screening of hydrodynamic interactions for polyelectrolytes in salt solution

    OpenAIRE

    Smiatek, Jens; Schmid, Friederike

    2008-01-01

    We provide numerical evidence that hydrodynamic interactions are screened for charged polymers in salt solution on time scales below the Zimm time. At very short times, a crossover to hydrodynamic behavior is observed. Our conclusions are drawn from extensive coarse-grained computer simulations of polyelectrolytes in explicit solvent and explicit salt, and discussed in terms of analytical arguments based on the Debye-Hueckel approximation.

  18. The Design of Polyelectrolyte Multilayers Using Galactosylated Chitosan

    OpenAIRE

    Arca, Hale Cigdem

    2012-01-01

    A major challenge in hepatic tissue engineering is that liver cells rapidly lose their phenotype in in vitro cell culture systems. For this reason, it is necessary to design biomaterials that can support and enhance hepatic functions. Hepatocytes have a surface protein, called the asialoglycoprotein receptor (ASGP-R), which interacts with galactose via a specific receptor-ligand interaction. Polyelectrolyte multilayers (PEMs) were prepared by the layer by layer method, which is based on elect...

  19. Polyelectrolytes to produce nanosized polydopamine.

    Science.gov (United States)

    Mateescu, Mihaela; Metz-Boutigue, Marie-Hélène; Bertani, Philippe; Ball, Vincent

    2016-05-01

    "Polydopamine" (PDA) is the oxidation product of dopamine and can be obtained as thin films covering the surface of all kinds of known materials and simultaneously as insoluble and useless precipitates from dopamine solutions in the presence of appropriate oxidants. The valorization of such precipitates to obtain stable suspensions of functional nanomaterials is highly desirable owing to the chemical and optical properties of PDA. We show that a vast repertoire of polyelectrolytes polycations as well as polyanions, allow to control the size of PDA particles in the 10-100nm size range. Simultaneously to the production of smaller nanoparticles, a progressive inhibition of PDA deposition on the surface of quartz plates (as well as on the surface of the reaction vessel) is found as the concentration of the polyelectrolytes is increased in the dopamine solution. The mechanism of size control-inhibition of film deposition is investigated in the particular case of poly(allylamine) but remains not understood in the case of polyanions. PMID:26890383

  20. Adsorption of dispersing polyelectrolytes: stabilization of drilling fluids; Adsorption de polyelectrolytes dispersants: stabilisation des fluides de forage

    Energy Technology Data Exchange (ETDEWEB)

    Balastre, M.

    1999-11-10

    Instabilities of concentrated colloidal suspensions are a source of many industrial problems, as in drilling fluid formulations where aggregation and severe settling phenomena can occur. Low molecular weight polyelectrolyte dispersants are used to solve these problems, but their optimal use requires a better understanding of the phenomena that are involved. After materials characterization, adsorption mechanisms of two anionic polyelectrolytes (PANa, PSSNa) on a soluble substrate model, barium sulfate powder are studied. Barium sulfate is the principal additive used to adapt the density of drilling fluids. A simple model allows us to propose a distribution of the microscopic species at the interface. Presence of divalent ions induces the formation of a strong complex with the polyelectrolyte. Adsorption and electro-kinetic data are presented and exchange equilibrium are examined in relation with the surface uptake. The binding mechanism and the surface speciation of the polymer groups are deduced from the ion exchange analysis. The macroscopic behavior of suspensions on different conditions (volume fraction, ionic strength, dispersant concentration) is studied by settling and rheological measurements. The macroscopic properties are connected to structural aspects, and we show that dispersing effects are mostly related to electro-steric repulsion. The dispersion state depends on two principal factors adsorbed amounts and adsorbed layer properties, especially the excess charge, and the molecules conformation. (author)

  1. Superhydrophilic Polyelectrolyte Brush Layers with Imparted Anti-Icing Properties

    DEFF Research Database (Denmark)

    Chernyy, Sergey; Järn, Mikael; Shimizu, Kyoko;

    2014-01-01

    This work demonstrates the feasibility of superhydrophilic polyelectrolyte brush coatings for anti-icing applications. Five different types of ionic and nonionic polymer brush coatings of 25-100 nm thickness were formed on glass substrates using silane chemistry for surface premodification follow......) that is enhanced in the presence of highly hydrated ions at the interface. It is suggested that the ability of ions to coordinate water is directly related to the efficiency of a given anti-icing coating based on the polyelectrolyte brush concept.......(-), SO4(2-), and C12SO3(-) ions. By consecutive measurements of the strength of ice adhesion toward ion-incorporated polymer brushes on glass it was found that Li(+) ions reduce ice adhesion by 40% at -18 °C and 70% at -10 °C. Ag(+) ions reduce ice adhesion by 80% at -10 °C relative to unmodified glass...

  2. Proton and metal ion binding to natural organic polyelectrolytes-I. Studies with synthetic model compounds

    Science.gov (United States)

    Marinsky, J.A.; Reddy, M.M.

    1984-01-01

    A unified physico-chemical model, based on a modified Henderson-Hasselbalch equation, for the analysis of ion complexation reactions involving charged polymeric systems is presented and verified. In this model pH = pKa+p(??Ka) + log(??/1 - ??) where Ka is the intrinsic acid dissociation constant of the ionizable functional groups on the polymer, ??Ka is the deviation of the intrinsic constant due to electrostatic interaction between the hydrogen ion and the polyanion, and alpha (??) is the polyacid degree of ionization. Using this approach pKa values for repeating acidic units of polyacrylic (PAA) and polymethacrylic (PMA) acids were found to be 4.25 ?? 0.03 and 4.8 ?? 0.1, respectively. The polyion electrostatic deviation term derived from the potentiometric titration data (i.e. p(??Ka)) is used to calculate metal ion concentration at the complexation site on the surface of the polyanion. Intrinsic cobalt-polycarboxylate binding constants (7.5 for PAA and 5.6 for PMA), obtained using this procedure, are consistent with the range of published binding constants for cobalt-monomer carboxylate complexes. In two phase systems incorporation of a Donnan membrane potential term allows determination of the intrinsic pKa of a cross-linked PMA gel, pKa = 4.83, in excellent agreement with the value obtained for the linear polyelectrolyte and the monomer. Similarly, the intrinsic stability constant for cobalt ion binding to a PMA-gel (??CoPMA+ = 11) was found to be in agreement with the linear polyelectrolyte analogue and the published data for cobalt-carboxylate monodentate complexes. ?? 1984.

  3. Complex Wavelet Based Modulation Analysis

    DEFF Research Database (Denmark)

    Luneau, Jean-Marc; Lebrun, Jérôme; Jensen, Søren Holdt

    2008-01-01

     because only the magnitudes are taken into account and the phase data is often neglected. We remedy this problem with the use of a complex wavelet transform as a more appropriate envelope and phase processing tool. Complex wavelets carry both magnitude and phase explicitly with great sparsity and preserve well...... polynomial trends. Moreover an analytic Hilbert-like transform is possible with complex wavelets implemented as an orthogonal filter bank. By working in an alternative transform domain coined as “Modulation Subbands”, this transform shows very promising denoising capabilities and suggests new approaches for joint...

  4. Dynamic Ordering Transitions of Liquid Crystals Driven by Interfacial Complexes Formed Between Polyanions and Amphiphilic Polyamines

    Science.gov (United States)

    Kinsinger, Michael I.; Buck, Maren E.; Campos, Fernando

    2011-01-01

    We report the design of an amphiphilic polyamine based on poly(2-alkenyl azlactone) (polymer 1) that strongly couples the formation of polyelectrolyte complexes at aqueous/liquid crystal (LC) interfaces to ordering transitions in the LC. We demonstrate that the addition of a strong anionic polyelectrolyte to aqueous solutions in contact with polymer 1-laden LC interfaces (prepared by Langmuir-Schaefer transfer of monolayers of polymer 1 onto micrometer-thick films of nematic LC) triggers ordering transitions in the LCs. We further demonstrate that changes in the ordering of the LCs (i) are driven by electrostatic interactions between the polyelectrolytes, (ii) involve multivalent interactions between the polyelectrolytes, and (iii) are triggered by reorganization of the hydrophobic side chains of amphiphilic polymer 1 upon formation of the interfacial complexes. The results presented in this paper lead us to conclude that ordering transitions in LCs can be used to provide insights into the structure and dynamics of interfacial complexes formed between polyelectrolytes. PMID:18991416

  5. Effect of Moisture on the Electrorheological Properties of Chitosan and Chitosan-Cu2+ Complex Polyelectrolyte Particles%水分对甲壳胺类高分子聚电解质的 电流变剪切性能的影响

    Institute of Scientific and Technical Information of China (English)

    张建华; 陶德华; 张直明

    2001-01-01

    The effect of moisture on the electrorheological (ER) propertiesof polyelectrolyte suspensions of chitosan and chitosan-Cu2+ complex particles dispersed in castor oil was investigated. It has been found that the polyelectrolyte suspensions did not show ER effect in the absence of moisture. The value of shear stress (τ) or apparent shear stress (Δτ) increased with the increase of moisture content and no saturated phenomenon was observed. When the moisture content came to about 12.5% of the dispersed particle content, a sharp increase in the leaking current density (J) appeared. Furthermore, the action mechanism of moisture in the polyelectrolyte suspensions of chitosan and chitosan-Cu2+ complex particles dispersed in castor oil is governed by its content therein and the compositions of the suspensions. Under the action of electric field or moisture, the -NH2 of chitoson or chitoson-Cu2+ complex particles are easy to dissociate from the polyelectrolytes bond to form the movable ions (-NH3+). When the moisture content is lower, the number of -NH3+ increases with the increase of its content. The ER effect is enhanced because -NH3+ can enlarge the induced-dipoile of the solid particles. On the other hand, for the suspension compositional molecules having hydrogen bond (—OH), when the moisture content is higher, the hydrogen bond action is stronger and thus it is easy to form “hydrogen bond bridge” with the co-action of the electric field. So the higher of the moisture, the larger the number of -NH3+ or hydrogen bond bridges in the suspension compositional molecules, the stronger the ER properties. The effect of moisture on the J is also elucidated by the same action mechanism. When moisture content is lower, the main action of -NH3+ is to enhance the induced dipolar interaction of the polyelectrolyte particles and there are ont any transit particles, so the value of J is lower. Which moisture content is higher, the “free water” in the suspensions will

  6. Durer-pentagon-based complex network

    Directory of Open Access Journals (Sweden)

    Rui Hou

    2016-04-01

    Full Text Available A novel Durer-pentagon-based complex network was constructed by adding a centre node. The properties of the complex network including the average degree, clustering coefficient, average path length, and fractal dimension were determined. The proposed complex network is small-world and fractal.

  7. Estudo das interações entre o complexo polieletrolítico trimetilquitosana/carboximetilcelulose e Cu+2, ácido húmico e atrazina em solução aquosa Study of the interactions between the polyelectrolyte complex trimethylchitosan/carboxymethylcellulose and Cu+2, humic acid and atrazine in aqueous solution

    Directory of Open Access Journals (Sweden)

    Sergio P. Campana-Filho

    2009-01-01

    Full Text Available The polyelectrolyte complex (PEC resulting from the reaction of sodium carboxymethylcellulose (CMC and N,N,N-trimethylchitosan hydrochloride (TMQ was prepared and then characterized by infrared spectroscopy and energy dispersive X rays analysis. The interactions involving the PEC and Cu2+ ions, humic acid and atrazine in aqueous medium were studied. From the adsorption isotherms the maximum amount adsorbed (Xmax was determined as 61 mg Cu2+/g PEC, 171 mg humic acid/g PEC and 5 mg atrazine/g PEC. The results show that the CMC/TMQ complex has a high affinity for the studied species, indicating its potential application to remove them from aqueous media.

  8. Responsive polyelectrolyte hydrogels and soft matter micromanipulation

    NARCIS (Netherlands)

    Glazer, P.J.

    2013-01-01

    This dissertation describes experimental studies on the mechanisms underlying the dynamic response of polyelectrolyte hydrogels when submitted to an external electric potential. In addition, we explore the possibilities of miniaturization and manipulation of responsive gels and other soft matter sys

  9. Functionalized conjugated polyelectrolytes design and biomedical applications

    CERN Document Server

    Wang, Shu

    2013-01-01

    Functionalized Conjugated Polyelectrolytes presents a comprehensive review of these polyelectrolytes and their biomedical applications. Basic aspects like molecular design and optoelectronic properties are covered in the first chapter. Emphasis is placed on the various applications including sensing (chemical and biological), disease diagnosis, cell imaging, drug/gene delivery and disease treatment. This book explores a multi-disciplinary topic of interest to researchers working in the fields of chemistry, materials, biology and medicine. It also offers an integrated perspective on both basic

  10. Waste-moulding dusts modified with polyelectrolytes

    OpenAIRE

    A. Baliński

    2010-01-01

    In the article described problems of the influence of advanced oxidizing process, the supersonic tooling of waste - moulding dusts and their modification with polyelectrolytes, on the technological proprieties of the moulding sands prepared with their participation.Physicochemical characterization of the used polyelectrolytes PSS (poli 4-styreno sodium sulfonate) and PEI (poli etyleno imine), in theaspect of their modificatory influences on the waste - moulding dust, was described. Defined th...

  11. Nonlinear Elasticity of Single Collapsed Polyelectrolytes

    OpenAIRE

    Wada, Hirofumi; Murayama, Yoshihiro; Sano, Masaki

    2004-01-01

    Nonlinear elastic responses of short and stiff polyelectrolytes are investigated by dynamic simulations on a single molecule level. When a polyelectrolyte condensate undergoes a mechanical unfolding, two types of force-extension curves, i.e., a force plateau and a stick-release pattern, are observed depending on the strength of the electrostatic interaction. We provide a physical interpretation of such force-extension behavior in terms of intramolecular structures of the condensates. We also ...

  12. Pegylated polyelectrolyte nanoparticles containing paclitaxel as a promising candidate for drug carriers for passive targeting.

    Science.gov (United States)

    Szczepanowicz, Krzysztof; Bzowska, Monika; Kruk, Tomasz; Karabasz, Alicja; Bereta, Joanna; Warszynski, Piotr

    2016-07-01

    Targeted drug delivery systems are of special importance in cancer therapies, since serious side effects resulting from unspecific accumulation of highly toxic chemotherapeutics in healthy tissues can restrict effectiveness of the therapy. In this work we present the method of preparing biocompatible, polyelectrolyte nanoparticles containing the anticancer drug that may serve as a vehicle for passive tumor targeting. The nanoparticles were prepared via direct encapsulation of emulsion droplets in a polyelectrolyte multilayer shell. The oil cores that contained paclitaxel were stabilized by docusate sodium salt/poly-l-lysine surface complex (AOT/PLL) and were encapsulated in shells formed by the LbL adsorption of biocompatible polyelectrolytes, poly-L-glutamic acid (PGA) and PLL up to 5 or 6 layers. The surface of the nanoparticles was pegylated through the adsorption of the pegylated polyelectrolyte (PGA-g-PEG) as the outer layer to prolong the persistence of the nanocarriers in the circulation. The synthesized nanoparticles were stable in cell culture medium containing serum and their average size was 100nm, which makes them promising candidates for passive targeted drug delivery. This notion was further confirmed by the results of studying the biological effects of nanoformulations on two tumor cell lines: mouse colon carcinoma cell line CT26-CEA and the mouse mammary carcinoma cell line 4T1. The empty polyelectrolyte nanoparticles did not affect the viability of the tested cells, whereas encapsulated paclitaxel retained its strong cytotoxic/cytostatic activity. PMID:27037784

  13. Influence of Higher Valence Ions on Flexible Polyelectrolytes Stiffness and Counter-ion Distribution

    Science.gov (United States)

    Chremos, Alexandros; Douglas, Jack F.

    We investigate the influence of counter-ion valency on the flexibility of highly charged flexible polymer chains by molecular dynamics simulations that include both salt and an explicit solvent. A theoretical understanding of solutions of these molecules (e.g., DNA, RNA, and sulfonate polyestyrene) has been slow to develop due to the complex coupling between the polyelectrolyte conformation and the ionic species in solution due to their long range Coulomb interactions. As observed experimentally, we find that divalent counter-ions greatly reduce the chain persistence length, in comparison to monovalent counter-ions, an effect correlated with the tendency of the polyelectrolyte chain to become distorted by divalent counter-ions. We rationalize these results by with the substantial increase of counter-ion population at the interface with the polyelectrolyte, which not only leads to a more effective screening of the bare charge, but also leads to charge inversion in the trivalent counter-ion case. These conformational changes with counter-ion valency are also associated with a drastic increase of the number of contacts the counter-ions have at the interface with polyelectrolyte, an effect associated with polyelectrolyte chain ``coiling'' around the counter-ions. NIST Postdoctoral Fellowship.

  14. Polyelectrolyte adsorption onto like-charged surfaces mediated by trivalent counterions: A Monte Carlo simulation study

    Science.gov (United States)

    Luque-Caballero, Germán; Martín-Molina, Alberto; Quesada-Pérez, Manuel

    2014-05-01

    Both experiments and theory have evidenced that multivalent cations can mediate the interaction between negatively charged polyelectrolytes and like-charged objects, such as anionic lipoplexes (DNA-cation-anionic liposome complexes). In this paper, we use Monte Carlo simulations to study the electrostatic interaction responsible for the trivalent-counterion-mediated adsorption of polyelectrolytes onto a like-charged planar surface. The evaluation of the Helmholtz free energy allows us to characterize both the magnitude and the range of the interaction as a function of the polyelectrolyte charge, surface charge density, [3:1] electrolyte concentration, and cation size. Both polyelectrolyte and surface charge favor the adsorption. It should be stressed, however, that the adsorption will be negligible if the surface charge density does not exceed a threshold value. The effect of the [3:1] electrolyte concentration has also been analyzed. In certain range of concentrations, the counterion-mediated attraction seems to be independent of this parameter, whereas very high concentrations of salt weaken the adsorption. If the trivalent cation diameter is doubled the adsorption moderates due to the excluded volume effects. The analysis of the integrated charge density and ionic distributions suggests that a delicate balance between charge inversion and screening effects governs the polyelectrolyte adsorption onto like-charged surfaces mediated by trivalent cations.

  15. Changes of Resistance During Polyelectrolyte-enhanced Stirred Batch Ultrafiltration

    Institute of Scientific and Technical Information of China (English)

    ZHU Xin-Sheng; Kwang-Ho CHOO

    2007-01-01

    The permeation flux or the resistance in the ultrafiltration process is mainly limited by osmotic pressure,and it may originate from various kinds of polymer interactions. However, the real origin of permeation resistance hasn't been clarified yet in the light of polymer solution nature. The removal of nitrate contamination by polyelectrolytes was carried out with stirred batch ultrafiltration. The polyelectrolyte concentrations both in permeate and retentate were analyzed with total organic carbon analyzer and permeate mass was acquired by electronic balance connected with computer. The total resistance was calculated and interpreted based on the osmotic pressures in three concentration regimes. In the dilute region, the resistance was proportional to polymer concentration; in the semidilute region, the resistance depended on polymer concentration in the parabolic relationship; in the highly concentrated solution regime, the osmotic pressure factor (OPF) would dominate the total resistance; and the deviation from OPF control could come from the electrostatic repulsion between the tightly compacted and charged polyelectrolyte particles at extremely concentrated solution regime. It was first found that dilute and semidilute concentration regions can be easily detected by plotting the log-log curves of the polymer concentration versus the ratio of the total resistance to polymer concentration. The new concept OPF was defined and did work well at highly concentrated regime.

  16. Charge correlation effects on ionization of weak polyelectrolytes

    International Nuclear Information System (INIS)

    Ionization curves of weak polyelectrolytes were obtained as a function of the charge coupling strength from Monte Carlo simulations. In contrast to many earlier studies, the present work treats counterions explicitly, thus allowing the investigation of charge correlation effects at strong couplings. For conditions representing typical weak polyelectrolytes in water near room temperature, ionization is suppressed because of interactions between nearby dissociated groups, as also seen in prior work. A novel finding here is that, for stronger couplings, relevant for non-aqueous environments in the absence of added salt, the opposite behavior is observed-ionization is enhanced relative to the behavior of the isolated groups due to ion-counterion correlation effects. The fraction of dissociated groups as a function of position along the chain also behaves non-monotonically. Dissociation is highest near the ends of the chains for aqueous polyelectrolytes and highest at the chain middle segments for non-aqueous environments. At intermediate coupling strengths, dissociable groups appear to behave in a nearly ideal fashion, even though chain dimensions still show strong expansion effects due to ionization. These findings provide physical insights on the impact of competition between acid/base chemical equilibrium and electrostatic attractions in ionizable systems.

  17. Charge correlation effects on ionization of weak polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Panagiotopoulos, A Z, E-mail: azp@princeton.ed [Department of Chemical Engineering and Institute for the Science and Technology of Materials, Princeton University, Princeton, NJ 08544 (United States)

    2009-10-21

    Ionization curves of weak polyelectrolytes were obtained as a function of the charge coupling strength from Monte Carlo simulations. In contrast to many earlier studies, the present work treats counterions explicitly, thus allowing the investigation of charge correlation effects at strong couplings. For conditions representing typical weak polyelectrolytes in water near room temperature, ionization is suppressed because of interactions between nearby dissociated groups, as also seen in prior work. A novel finding here is that, for stronger couplings, relevant for non-aqueous environments in the absence of added salt, the opposite behavior is observed-ionization is enhanced relative to the behavior of the isolated groups due to ion-counterion correlation effects. The fraction of dissociated groups as a function of position along the chain also behaves non-monotonically. Dissociation is highest near the ends of the chains for aqueous polyelectrolytes and highest at the chain middle segments for non-aqueous environments. At intermediate coupling strengths, dissociable groups appear to behave in a nearly ideal fashion, even though chain dimensions still show strong expansion effects due to ionization. These findings provide physical insights on the impact of competition between acid/base chemical equilibrium and electrostatic attractions in ionizable systems.

  18. Charge-regularization effects on polyelectrolytes

    Science.gov (United States)

    Muthukumar, Murugappan

    2012-02-01

    When electrically charged macromolecules are dispersed in polar solvents, their effective net charge is generally different from their chemical charges, due to competition between counterion adsorption and the translational entropy of dissociated counterions. The effective charge changes significantly as the experimental conditions change such as variations in solvent quality, temperature, and the concentration of added small electrolytes. This charge-regularization effect leads to major difficulties in interpreting experimental data on polyelectrolyte solutions and challenges in understanding the various polyelectrolyte phenomena. Even the most fundamental issue of experimental determination of molar mass of charged macromolecules by light scattering method has been difficult so far due to this feature. We will present a theory of charge-regularization of flexible polyelectrolytes in solutions and discuss the consequences of charge-regularization on (a) experimental determination of molar mass of polyelectrolytes using scattering techniques, (b) coil-globule transition, (c) macrophase separation in polyelectrolyte solutions, (c) phase behavior in coacervate formation, and (d) volume phase transitions in polyelectrolyte gels.

  19. Effect of Protein Supercharging on Interaction with Polyelectrolytes

    Science.gov (United States)

    Olsen, Bradley; Obermeyer, Allie; Mills, Carolyn; Dong, Xuehui

    Complexation of proteins with polyelectrolytes can lead to a liquid-liquid phase separation to generate a viscous complex coacervate phase rich in protein and polyelectrolyte. However, many proteins do not readily coacervate at conditions near neutral pH and physiological ionic strength. Here, protein supercharging is used to systematically explore the effect of protein charge on the complex coacervation with polycations. Four model proteins were chemically modified to generate a panel of proteins with varying surface charge, with both the average charge and charge distribution quantified by mass spectrometry. Proteins phase separated with the qP4VP and qPDMAEMA polycations when the ratio of negatively charged residues to positively charged residues was greater than 1.1-1.2. Efficient partitioning of the protein into the coacervate phase required larger charge ratio (1.5-2.0). The model proteins were also encapsulated in complex coacervate core micelles. Dynamic light scattering was used to assess the formation of micelles with POEGMA- b-qP4VP and revealed micellar hydrodynamic radii of approximately 25-30 nm. Small angle neutron scattering and transmission electron microscopy were used to confirm the formation of spherical micelles.

  20. An Introduction to Polyelectrolytes via the Physical Chemistry Laboratory.

    Science.gov (United States)

    Ander, Paul

    1979-01-01

    Polyelectrolytes are discussed with regard to their importance to the undergraduate science major enrolled in a physical chemistry course. Suggests the importance of the solution behavior of polyelectrolytes to scientific disciplines and many industries. (Author/SA)

  1. EFFECTS OF SYNTHETIC POLYELECTROLYTES ON SELECTED AQUATIC ORGANISMS

    Science.gov (United States)

    The acute toxicity of several polyelectrolytes to daphnids (Daphnia magna), fathead minnows (Pimephales promelas), gammarids (Gammarus pseudolimnaeus) and midges (Paratanytarsus parthenogeneticus) was tested. Most nonionic and anionic polyelectrolytes were not toxic at 100 mg/l w...

  2. Adaptive Beamforming Based on Complex Quaternion Processes

    Directory of Open Access Journals (Sweden)

    Jian-wu Tao

    2014-01-01

    Full Text Available Motivated by the benefits of array signal processing in quaternion domain, we investigate the problem of adaptive beamforming based on complex quaternion processes in this paper. First, a complex quaternion least-mean squares (CQLMS algorithm is proposed and its performance is analyzed. The CQLMS algorithm is suitable for adaptive beamforming of vector-sensor array. The weight vector update of CQLMS algorithm is derived based on the complex gradient, leading to lower computational complexity. Because the complex quaternion can exhibit the orthogonal structure of an electromagnetic vector-sensor in a natural way, a complex quaternion model in time domain is provided for a 3-component vector-sensor array. And the normalized adaptive beamformer using CQLMS is presented. Finally, simulation results are given to validate the performance of the proposed adaptive beamformer.

  3. Study of Physical and Colloid-Chemical Properties of Acrylic Polyelectrolytes of “M-PAA” Series and Their Modification

    OpenAIRE

    N.O Dzhakipbekova; A. B. Isa; M. F Fatkullina; E. O Dzhakipbekov

    2015-01-01

    The aim of this study is to search for the best basic technology to replace the base in the metallization of dielectrics. We studied conducting polymers – acrylic polyelectrolytes. Polyelectrolytes include high molecular weight compounds containing macromolecules and ionogenic groups. Experimental studies have shown that the rational use of HSP for the regulation of colloid-chemical processes in the production should take into account the functional structure of the polymer, its conformatio...

  4. Layer-by-layer self-assembly of polyelectrolyte functionalized MoS2 nanosheets.

    Science.gov (United States)

    Shen, Jianfeng; Pei, Yu; Dong, Pei; Ji, Jin; Cui, Zheng; Yuan, Junhua; Baines, Robert; Ajayan, Pulickel M; Ye, Mingxin

    2016-05-01

    Few-layered polyelectrolyte functionalized MoS2 nanosheets were obtained for the first time through in situ polymerization of MoS2 nanosheets with poly(acrylic acid) and poly(acrylamide), both of which demonstrated excellent dispersibility and stability in water. After designing and optimizing the components of this series of polyelectrolyte functionalized MoS2 nanosheets, by exploiting the electrostatic interactions present in the modified MoS2 nanosheets, we further created a series of layer-by-layer (LBL) self-assembling MoS2-based films. To this end, uniform MoS2 nanosheet-based LBL films were precisely deposited on substrates such as quartz, silicon, and ITO. The polyelectrolyte functionalized MoS2 nanosheet assembled LBL film-modified electrodes demonstrated enhanced electrocatalytic activity for H2O2. As such, they are conducive to efficient sensors and advanced biosensing systems.

  5. Reorganization of hydrogen bond network makes strong polyelectrolyte brushes pH-responsive

    Science.gov (United States)

    Wu, Bo; Wang, Xiaowen; Yang, Jun; Hua, Zan; Tian, Kangzhen; Kou, Ran; Zhang, Jian; Ye, Shuji; Luo, Yi; Craig, Vincent S. J.; Zhang, Guangzhao; Liu, Guangming

    2016-01-01

    Weak polyelectrolytes have found extensive practical applications owing to their rich pH-responsive properties. In contrast, strong polyelectrolytes have long been regarded as pH-insensitive based on the well-established fact that the average degree of charging of strong polyelectrolyte chains is independent of pH. The possible applications of strong polyelectrolytes in smart materials have, thus, been severely limited. However, we demonstrate that almost all important properties of strong polyelectrolyte brushes (SPBs), such as chain conformation, hydration, stiffness, surface wettability, lubricity, adhesion, and protein adsorption are sensitive to pH. The pH response originates from the reorganization of the interchain hydrogen bond network between the grafted chains, triggered by the pH-mediated adsorption-desorption equilibrium of hydronium or hydroxide with the brushes. The reorganization process is firmly identified by advanced sum-frequency generation vibrational spectroscopy. Our findings not only provide a new understanding of the fundamental properties of SPBs but also uncover an extensive family of building blocks for constructing pH-responsive materials.

  6. Systematic modification of the rheological properties of colloidal suspensions with polyelectrolyte multilayers.

    Science.gov (United States)

    Hess, Andreas; Pretzl, Melanie; Heymann, Lutz; Fery, Andreas; Aksel, Nuri

    2011-09-01

    Tailoring rheological properties of colloidal suspensions with the adsorption of polyelectrolyte multilayers (PEMs) is based on the idea of controlling macroscopic mechanical properties by modifying the particle surface in a reproducible and well-understood manner. With layer-by-layer self-assembly, monodisperse polystyrene particles are coated with up to ten layers of the oppositely charged strong polyelectrolytes: poly(diallyl dimethyl ammonium chloride) and poly(styrene sulfonate). The conformation of the adsorbed polyelectrolyte is controlled by the ionic strength of the used aqueous polyelectrolyte solution. For 1M NaCl solution, a brushlike adsorption of the polyelectrolyte is expected. The ability of PEMs to serve on a nanoscale level as surface modifiers and influence macroscopic rheological properties like viscoelasticity, yield stress, and shear banding is discussed. The mechanical behavior of these suspensions is qualitatively described by the theory of Derjaguin-Landau-Verwey-Overbeek with short-range repulsion and long-range attraction. A scaling rule is proposed which distinguishes between the precusor and the multilayer regime.

  7. Monte Carlo simulations of hydrophobic polyelectrolytes. Evidence for a structural transition in response to increasing chain ionization

    International Nuclear Information System (INIS)

    Monte Carlo simulation has been used to study the configurational properties of a lattice-model isolated polyelectrolyte with attractive segment--segment interaction potentials. This model provides a simple representation of a hydrophobic polyelectrolyte. Configurational properties were investigated as a function of chain ionization, Debye screening length, and segment--segment potential. For chains with highly attractive segment--segment potentials (i.e., hydrophobic chains), large, global changes in polymer dimensions were observed with increasing ionization. The transformation from a collapsed chain at low ionization to an expanded chain at high ionization becomes increasingly sharp (i.e., occurs over a smaller range of ionization) with increasing chain hydrophobicity. The ionization-induced structural transitions for this model hydrophobic polyelectrolyte are analogous to pH-induced transitions seen in real polyelectrolytes and gels. These studies suggest a simple explanation for such transitions based on competing hydrophilic and hydrophobic interactions

  8. Energy conversion in polyelectrolyte hydrogels

    Science.gov (United States)

    Olvera de La Cruz, Monica; Erbas, Aykut; Olvera de la Cruz Team

    Energy conversion and storage have been an active field of research in nanotechnology parallel to recent interests towards renewable energy. Polyelectrolyte (PE) hydrogels have attracted considerable attention in this field due to their mechanical flexibility and stimuli-responsive properties. Ideally, when a hydrogel is deformed, applied mechanical work can be converted into electrostatic, elastic and steric-interaction energies. In this talk, we discuss the results of our extensive molecular dynamics simulations of PE hydrogels. We demonstrate that, on deformation, hydrogels adjust their deformed state predominantly by altering electrostatic interactions between their charged groups rather than excluded-volume and bond energies. This is due to the hydrogel's inherent tendency to preserve electro-neutrality in its interior, in combination with correlations imposed by backbone charges. Our findings are valid for a wide range of compression ratios and ionic strengths. The electrostatic-energy alterations that we observe in our MD simulations may induce pH or redox-potential changes inside the hydrogels. The resulting energetic difference can be harvested, for instance, analogously to a Carnot engine, or facilitated for sensor applications. Center for Bio-inspired Energy Science (CBES).

  9. Swelling of biological and semiflexible polyelectrolytes

    International Nuclear Information System (INIS)

    We have developed a theoretical model of swelling of semiflexible (biological) polyelectrolytes in salt solutions. Our approach is based on separation of length scales which allowed us to split a chain's electrostatic energy into two parts that describe local and remote electrostatic interactions along the polymer backbone. The local part takes into account interactions between charged monomers that are separated by distances along the polymer backbone shorter than the chain's persistence length. These electrostatic interactions renormalize chain persistence length. The second part includes electrostatic interactions between remote charged pairs along the polymer backbone located at distances larger than the chain persistence length. These interactions are responsible for chain swelling. In the framework of this approach we calculated effective chain persistence length and chain size as a function of the Debye screening length, chain degree of ionization, bare persistence length and chain degree of polymerization. Our crossover expression for the effective chain's persistence length is in good quantitative agreement with the experimental data on DNA. We have been able to fit experimental datasets by using two adjustable parameters: DNA ionization degree (α = 0.15-0.17) and a bare persistence length (lp = 40-44 nm).

  10. Waste-moulding dusts modified with polyelectrolytes

    Directory of Open Access Journals (Sweden)

    A. Baliński

    2010-04-01

    Full Text Available In the article described problems of the influence of advanced oxidizing process, the supersonic tooling of waste - moulding dusts and their modification with polyelectrolytes, on the technological proprieties of the moulding sands prepared with their participation.Physicochemical characterization of the used polyelectrolytes PSS (poli 4-styreno sodium sulfonate and PEI (poli etyleno imine, in theaspect of their modificatory influences on the waste - moulding dust, was described. Defined the influence of adsorption proprieties ofthe polyelectrolyte PEI on the surface of small parts of the waste - dust, on technological proprieties of the sandmix. Ascertained theprofitable influence of this electrolyte on mechanical proprieties of the moulding sands, that is to say the increase in value of thecompression strength (about 10% and tensile strenght (about 13%, comparatively to analogous proprieties of the moulding sandsprepared with the participation of the not modified waste- dust.

  11. Simulation of annealed polyelectrolytes in poor solvents

    International Nuclear Information System (INIS)

    We present (semi-)grand canonical Monte Carlo simulations on annealed polyelectrolytes in poor solvent. Increasing the chemical potential of the charges, which is equal to the pH of the solution except for a trivial additive constant, in rather poor solvents, we find the first-order phase transition between a weakly charged globule and a highly charged extended chain predicted by theory. In the close-to-Q -point regime, we investigate under which conditions pearl-necklace structures are stable. Most of the pearl-necklace parameters are found to obey the scaling relations predicted for quenched polyelectrolytes. However, similarly to the behavior known for this class of polyelectrolytes we obtain large fluctuations in pearl number and size. In agreement with theoretical predictions we find a non-uniform charge distribution between pearls and strings

  12. Molecular Thermodynamic Model for Polyelectrolyte Solutions with Added Salts

    Institute of Scientific and Technical Information of China (English)

    ZHANGBo; CAIJun; 等

    2002-01-01

    A molecular thermodynamic model of polyelectrolyte developed previously was extended to polyelectrolyte solutions with added salts.Thermodynamic properties,such as activity coefficients of polyelectrolytes or added salts and osmotic coefficients of solvent, of a number of aqueous mixtures of polyelectrolytes and salts are analyzed with the proposed model.Successful correlation is obtained in the range of moderate or higher polyion concentration.For the same sample,thermodynamic properties of polyelectrolytes with and without simple electrolytes can be predicted mutually using parameters from regression data.

  13. Synthesis and Characterization of Photoresponsive Azo Polyelectrolytes

    Institute of Scientific and Technical Information of China (English)

    WU Lifeng; PENG Huagen; WANG Xiaogong; LIU Deshan; ZHOU Qixiang

    2001-01-01

    Optical active azo polymers are very important functional materials because of their photoresponsive properties.This paper investigates three kinds of aromatic azo polyelectrolytes synthesized by chemical modification of poly(acryloyl chloride)which was prepared by free radical polymerization.Poly was esterified with three different kinds of aromatic azo compounds containing hydroxyl groups to give polymeric intermediates,which were used to prepare the azo polyelectrolytes by hydrolysis.The products were characterized by elementary analysis,IR,1H-NMR,and UV-Vis spectrography.

  14. A Blocking Technique for Emulating Very Large Polyelectrolytes

    CERN Document Server

    Peterson, C; Söderberg, B

    1995-01-01

    A new Monte Carlo method for computing thermodynamical properties of very large polyelectrolytes is presented. It is based on a renormalization group relating the original polymer to a smaller system, where in addition to the naively rescaled forces, a corrective nearest-neighbor interaction originating from the short distance Coulomb cutoff is introduced. The method is derived for low T but is in the unscreened case valid for all T. Large polymers with N monomers are emulated by Monte Carlo calculations on smaller systems, K=N/Q. The computational gain of the method is Q^3. It is explored with emphasis on room temperature. Results for N=10000 are presented.

  15. Separation and Characterization of Synthetic Polyelectrolytes and Polysaccharides with Capillary Electrophoresis

    OpenAIRE

    Thevarajah, Joel J.; Marianne Gaborieau; Patrice Castignolles

    2014-01-01

    The development of macromolecular engineering and the need for renewable and sustainable polymer sources make polymeric materials progressively more sophisticated but also increasingly complex to characterize. Size-exclusion chromatography (SEC or GPC) has a monopoly in the separation and characterization of polymers, but it faces a number of proven, though regularly ignored, limitations for the characterization of a number of complex samples such as polyelectrolytes and polysaccharides. Free...

  16. Self-organized nanoparticles based on drug-interpolyelectrolyte complexes as drug carriers

    Energy Technology Data Exchange (ETDEWEB)

    Palena, M. C.; Manzo, R. H.; Jimenez-Kairuz, A. F., E-mail: alvaro@fcq.unc.edu.ar [Universidad Nacional de Cordoba, UNITEFA-CONICET, Departamento de Farmacia, Facultad de Ciencias Quimicas (Argentina)

    2012-06-15

    Potential applications in drug delivery from nanostructures composed of two oppositely charged polymethacrylates, eudragit{sup Registered-Sign} L100 (EL) and eudragit{sup Registered-Sign} EPO (EE), loaded with three model basic drugs (D), atenolol, propranolol, and metroclopramide were evaluated. The self-organized nanoparticles based on drug-interpolyelectrolyte complexes (DIPEC), (EL-D{sub 50})-EE{sub X}, were obtained by mixing the aqueous dispersions of both polyelectrolytes at room temperature in an ultrasound bath. Dispersions of (EL-D{sub 50}) neutralized with increasing proportions of EE exhibited a rise of turbidity, particle sizes in the range of 150-400 nm, and high negative zeta potential. The sign of zeta potential was shifted from negative to positive by changes in composition of DIPEC. Freeze dried DIPEC were easily redispersed in water yielding nearly the same parameters of fresh dispersions. In vitro release experiments using Franz cells showed that DIPEC systems behave as a drug reservoir that slowly releases the drug as water is placed in the receptor compartment. The release rate was raised by ionic exchange with counterions present in simulated physiological fluids placed in the receptor media. Delivery of D from DIPEC exhibited a remarkable robustness toward simulated physiological media of different pH. The DIPEC systems exhibit interesting properties to design nanoparticulate drug delivery systems for oral and/or topical routes.

  17. Nanoparticle-based membrane assembly and silicification in coacervate microdroplets as a route to complex colloidosomes.

    Science.gov (United States)

    Fothergill, James; Li, Mei; Davis, Sean A; Cunningham, John A; Mann, Stephen

    2014-12-01

    The chemical construction of complex colloidosomes consisting of a molecularly crowded polyelectrolyte-enriched interior surrounded by a continuous shell of closely packed silica nanoparticles is studied using optical and fluorescence microscopy, high-resolution X-ray microcomputed tomography, and synchrotron radiation X-ray tomographic microscopy. The colloidosomes are prepared by addition of partially hydrophobic silica nanoparticles to dodecane dispersions of positively or negatively charged coacervate microdroplets consisting of aqueous mixtures of poly(diallyldimethylammonium chloride) (PDDA) and adenosine 5'-triphosphate (ATP) or PDDA and poly(acrylic acid) (PAA), respectively. Interfacial assembly of the nanoparticles produces a polydisperse population of well-defined PDDA/PAA droplets with diameters ranging from 50 to 950 μm. In contrast, reconstruction of the PDDA/ATP coacervate interior occurs on addition of the silica nanoparticles to produce a nanoparticle-stabilized oil-in-coacervate-in-oil multiphase emulsion. Transfer of the coacervate-containing colloidosomes into water and replication of their internal structure are achieved by addition of tetramethoxysilane, which serves as both a cross-linking and silicification agent to produce mineralized PDDA/PAA or PDDA/ATP microstructures with a uniform solidified texture or multichambered interior, respectively. The integration of colloidosome and coacervate technologies offers a route to a new type of multifunctional microcompartmentalized system based on the membrane-mediated incarceration of molecularly crowded chemical environments.

  18. Polyelectrolyte hydrogels and methods of their preparation

    International Nuclear Information System (INIS)

    This invention relates to polyelectrolyte polymers which are water insoluble but water swellable, and methods for producing them. More particularly, it relates to cross-linked, random copolymers comprised of an acrylate salt and acrylamide and methods of producing them by means of a controlled dose and controlled intensity of ionizing radiation. (author)

  19. Spherical Polyelectrolyte Brushes and Their Films

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Nano-sized spherical polyelectrolyte brushes (SPB), which consist of a solid polystyrene core and linear poly(acrylic acid) (PAA) chains covalently attached on the core surface by one end with different lengths and grafting densities, were prepared by photo-emulsion polymerization and thermo- controlled emulsion polymerization.

  20. Surface-induced layer formation in polyelectrolytes

    OpenAIRE

    Solis, F. J.; de la Cruz, M. Olvera

    1998-01-01

    We analyze, by means of an RPA calculation, the conditions under which a mixture of oppositely charged polyelectrolytes can micro-segregate in the neighborhood of a charged surface creating a layered structure. A number of stable layers can be formed if the surface is sufficiently strongly charged even at temperatures at which the bulk of the mixture is homogeneous.

  1. Polyelectrolytes in Solution - Recent Computer Simulations

    OpenAIRE

    Holm, Christian; Kremer, Kurt

    1998-01-01

    We present a short overview over recent MD simulations of systems of fully flexible polyelectrolyte chains with explicitly treated counter ions using the full Coulomb potential. The main emphasis is given on the conformational properties of the polymers, with a short discussion on counter ion condensation.

  2. Investigation of complexing ability of ionites with various groups to some heavy and transition metal ions

    Directory of Open Access Journals (Sweden)

    Yedil Yergozhin

    2013-05-01

    Full Text Available The physico-chemical and complexing properties of the sorbent based on chloromethylated styrene and divinylbenzene copolymer with nicotinamide groups and copolymers based on metacryloilaminobenzene acids with 2-methyl-5-vinylpyridineisomers are studied. By potentiometric titration method the constant of polyelectrolytes functional groups ionization, the composition and strength of the resulting complexes with ions of some heavy and transition metals are determined.

  3. Phenalenyl-based mononuclear dysprosium complexes.

    Science.gov (United States)

    Lan, Yanhua; Magri, Andrea; Fuhr, Olaf; Ruben, Mario

    2016-01-01

    The phenalenyl-based dysprosium complexes [Dy(PLN)2(HPLN)Cl(EtOH)] (1), [Dy(PLN)3(HPLN)]·[Dy(PLN)3(EtOH)]·2EtOH (2) and [Dy(PLN)3(H2O)2]·H2O (3), HPLN being 9-hydroxy-1H-phenalen-1-one, have been synthesized. All compounds were fully characterized by means of single crystal X-ray analysis, paramagnetic (1)H NMR, MALDI-TOF mass spectrometry, UV-vis spectrophotometry and magnetic measurements. Both static (dc) and dynamic (ac) magnetic properties of these complexes have been investigated, showing slow relaxation of magnetization, indicative of single molecule magnet (SMM) behavior. Attempts to synthesize sublimable phenalenyl-based dysprosium complexes have been made by implementing a synthetic strategy under anhydrous conditions. The sublimed species were characterized and their thermal stability was confirmed. This opens up the possibility to deposit phenalenyl-based lanthanides complexes by sublimation onto surfaces, an important prerequisite for ongoing studies in molecular spintronics. PMID:27547617

  4. Influence of anionic and cationic polyelectrolytes on the conductivity and morphology of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) films

    International Nuclear Information System (INIS)

    Conductivity of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) strongly depends on the film morphology, which can be altered by the presence of polyelectrolytes. Aqueous dispersion of PEDOT:PSS was studied with anionic sodium polyacrylate (PA) and cationic poly(dimethyldiallylammonium chloride) (pDADMAC) polyelectrolytes that are typically used in papermaking as retention aids and dispersing agents in the paper pigment coating formulations. Spin-coated PEDOT:PSS films on a PA coated glass formed non-uniform layers with lowered conductivity compared to the reference PEDOT:PSS films on a clean glass substrate. On contrary, spin-coated PEDOT:PSS on a pDADMAC coated glass formed uniform layers with good conductivity. These results point out the importance of surface chemistry when using renewable and recyclable paper-based substrates with the PEDOT:PSS films. - Highlights: • PEDOT:PSS polymer was studied in the presence of polyelectrolytes. • Uniform layers of PEDOT:PSS and polyelectrolytes were spin-coated on glass. • Cationic polyelectrolyte was found to be more susceptible to humidity. • Cationic polyelectrolyte improves the conductivity of PEDOT:PSS. • PEDOT:PSS forms non-uniform layers on anionic polyelectrolyte coated glass

  5. Influence of anionic and cationic polyelectrolytes on the conductivity and morphology of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) films

    Energy Technology Data Exchange (ETDEWEB)

    Valtakari, Dimitar, E-mail: dimitar.valtakari@abo.fi [Abo Akademi University, Laboratory of Paper Coating and Converting, Center for Functional Materials at Biological Interfaces (FUNMAT), Porthansgatan 3, FI-20500 Åbo/Turku (Finland); Bollström, Roger [Omya International AG, CH 4665 Oftringen (Switzerland); Toivakka, Martti; Saarinen, Jarkko J. [Abo Akademi University, Laboratory of Paper Coating and Converting, Center for Functional Materials at Biological Interfaces (FUNMAT), Porthansgatan 3, FI-20500 Åbo/Turku (Finland)

    2015-09-01

    Conductivity of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) strongly depends on the film morphology, which can be altered by the presence of polyelectrolytes. Aqueous dispersion of PEDOT:PSS was studied with anionic sodium polyacrylate (PA) and cationic poly(dimethyldiallylammonium chloride) (pDADMAC) polyelectrolytes that are typically used in papermaking as retention aids and dispersing agents in the paper pigment coating formulations. Spin-coated PEDOT:PSS films on a PA coated glass formed non-uniform layers with lowered conductivity compared to the reference PEDOT:PSS films on a clean glass substrate. On contrary, spin-coated PEDOT:PSS on a pDADMAC coated glass formed uniform layers with good conductivity. These results point out the importance of surface chemistry when using renewable and recyclable paper-based substrates with the PEDOT:PSS films. - Highlights: • PEDOT:PSS polymer was studied in the presence of polyelectrolytes. • Uniform layers of PEDOT:PSS and polyelectrolytes were spin-coated on glass. • Cationic polyelectrolyte was found to be more susceptible to humidity. • Cationic polyelectrolyte improves the conductivity of PEDOT:PSS. • PEDOT:PSS forms non-uniform layers on anionic polyelectrolyte coated glass.

  6. Novel application of polyelectrolyte multilayers as nanoscopic closures with hermetic sealing.

    Science.gov (United States)

    Marcott, Stephanie A; Ada, Sena; Gibson, Phillip; Camesano, Terri A; Nagarajan, R

    2012-03-01

    Closure systems for personnel protection applications, such as protective clothing or respirator face seals, should provide effective permeation barrier to toxic gases. Currently available mechanical closure systems based on the hook and loop types (example, Velcro) do not provide adequate barrier to gas permeation. To achieve hermetic sealing, we propose a nonmechanical, nanoscopic molecular closure system based on complementary polyelectrolyte multilayers, one with a polycation outermost layer and the other with a polyanion outermost layer. The closure surfaces were prepared by depositing polyelectrolyte multilayers under a variety of deposition conditions, on conformable polymer substrates (thin films of polyethylene teraphthalate, PET or polyimide, PI). The hermetic sealing property of the closures was evaluated by measuring the air flow resistance using the dynamic moisture permeation cell (DMPC) at different humidity conditions. The DMPC measurements show that the polyelectrolyte multilayer closures provide significantly large resistance to air flow, approximately 20-800 times larger than that possible with conventional hook and loop type closure systems, at all humidity levels (from 5 to 95% relative humidity). Hence, from the point of view of providing a hermetic seal against toxic gas permeation, the polyelectrolyte multilayer closures are viable candidates for further engineering development. However, the adhesive strength of the multilayer closures measured by atomic force microscopy suggests that the magnitude of adhesion is much smaller than what is possible with mechanical closures. Therefore, we envisage the development of a composite closure system combining the mechanical closure to provide strong adhesion and the multilayer closure to provide hermetic sealing. PMID:22391415

  7. Bicontinuous Fluid Structure with Low Cohesive Energy: Molecular Basis for Exceptionally Low Interfacial Tension of Complex Coacervate Fluids.

    Science.gov (United States)

    Huang, Kuo-Ying; Yoo, Hee Young; Jho, YongSeok; Han, Songi; Hwang, Dong Soo

    2016-05-24

    An exceptionally low interfacial tension of a dense fluid of concentrated polyelectrolyte complexes, phase-separated from a biphasic fluid known as complex coacervates, represents a unique and highly sought-after materials property that inspires novel applications from superior coating to wet adhesion. Despite extensive studies and broad interest, the molecular and structural bases for the unique properties of complex coacervates are unclear. Here, a microphase-separated complex coacervate fluid generated by mixing a recombinant mussel foot protein-1 (mfp-1) as the polycation and hyaluronic acid (HA) as the polyanion at stoichiometric ratios was macroscopically phase-separated into a dense complex coacervate and a dilute supernatant phase to enable separate characterization of the two fluid phases. Surprisingly, despite up to 4 orders of magnitude differing density of the polyelectrolytes, the diffusivity of water in these two phases was found to be indistinguishable. The presence of unbound, bulk-like, water in the dense fluid can be reconciled with a water population that is only weakly perturbed by the polyelectrolyte interface and network. This hypothesis was experimentally validated by cryo-TEM of the macroscopically phase-separated dense complex coacervate phase that was found to be a bicontinuous and biphasic nanostructured network, in which one of the phases was confirmed by staining techniques to be water and the other polyelectrolyte complexes. We conclude that a weak cohesive energy between water-water and water-polyelectrolytes manifests itself in a bicontinuous network, and is responsible for the exceptionally low interfacial energy of this complex fluid phase with respect to virtually any surface within an aqueous medium.

  8. Bicontinuous Fluid Structure with Low Cohesive Energy: Molecular Basis for Exceptionally Low Interfacial Tension of Complex Coacervate Fluids.

    Science.gov (United States)

    Huang, Kuo-Ying; Yoo, Hee Young; Jho, YongSeok; Han, Songi; Hwang, Dong Soo

    2016-05-24

    An exceptionally low interfacial tension of a dense fluid of concentrated polyelectrolyte complexes, phase-separated from a biphasic fluid known as complex coacervates, represents a unique and highly sought-after materials property that inspires novel applications from superior coating to wet adhesion. Despite extensive studies and broad interest, the molecular and structural bases for the unique properties of complex coacervates are unclear. Here, a microphase-separated complex coacervate fluid generated by mixing a recombinant mussel foot protein-1 (mfp-1) as the polycation and hyaluronic acid (HA) as the polyanion at stoichiometric ratios was macroscopically phase-separated into a dense complex coacervate and a dilute supernatant phase to enable separate characterization of the two fluid phases. Surprisingly, despite up to 4 orders of magnitude differing density of the polyelectrolytes, the diffusivity of water in these two phases was found to be indistinguishable. The presence of unbound, bulk-like, water in the dense fluid can be reconciled with a water population that is only weakly perturbed by the polyelectrolyte interface and network. This hypothesis was experimentally validated by cryo-TEM of the macroscopically phase-separated dense complex coacervate phase that was found to be a bicontinuous and biphasic nanostructured network, in which one of the phases was confirmed by staining techniques to be water and the other polyelectrolyte complexes. We conclude that a weak cohesive energy between water-water and water-polyelectrolytes manifests itself in a bicontinuous network, and is responsible for the exceptionally low interfacial energy of this complex fluid phase with respect to virtually any surface within an aqueous medium. PMID:27152954

  9. Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

    CERN Document Server

    Voisin, D

    2002-01-01

    Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each po...

  10. Molecular dynamics simulation study of polyelectrolyte adsorption on cellulose surfaces

    OpenAIRE

    Biermann, Oliver

    2002-01-01

    The adsorption of two polyelectrolyte ((carboxy methyl) cellulose and poly(acrylate) in water on crystalline cellulose is studied in this work. The multi-component problem has been splitted up into simulations of solutions of the polyelectrolyte (polyanions including sodium counterions) in water, into simulations of the interface of crystalline cellulose towards water. Finally polyelectrolyte-cellulose systems were studied. Molecular dynamics simulations of diluted (_ 2:5 weight percent) aque...

  11. Generation of Functionalized and Robust Semiconducting Polymer Dots with Polyelectrolytes

    OpenAIRE

    Jin, Yuhui; Ye, Fangmao; Wu, Changfeng; Chan, Yang-Hsiang; Chiu, Daniel T.

    2012-01-01

    We describe a facile method to functionalize semiconducting polymer dots (Pdots) with polyelectrolytes. The polyelectrolyte coating dramatically improves the colloidal stability of the Pdots in solutions which are either of high ionic strength or contain bivalent metal ions: This feature allows Pdots to be used under physiologically relevant environments without losing their functionality. We conjugated the polyelectrolyte-coated Pdots with streptavidin to demonstrate their application in spe...

  12. Responsive block copolymer photonics triggered by protein-polyelectrolyte coacervation.

    Science.gov (United States)

    Fan, Yin; Tang, Shengchang; Thomas, Edwin L; Olsen, Bradley D

    2014-11-25

    Ionic interactions between proteins and polyelectrolytes are demonstrated as a method to trigger responsive transitions in block copolymer (BCP) photonic gels containing one neutral hydrophobic block and one cationic hydrophilic block. Poly(2-vinylpyridine) (P2VP) blocks in lamellar poly(styrene-b-2-vinylpyridine) block copolymer thin films are quaternized with primary bromides to yield swollen gels that show strong reflectivity peaks in the visible range; exposure to aqueous solutions of various proteins alters the swelling ratios of the quaternized P2VP (QP2VP) gel layers in the PS-QP2VP materials due to the ionic interactions between proteins and the polyelectrolyte. Parameters such as charge density, hydrophobicity, and cross-link density of the QP2VP gel layers as well as the charge and size of the proteins play significant roles on the photonic responses of the BCP gels. Differences in the size and pH-dependent charge of proteins provide a basis for fingerprinting proteins based on their temporal and equilibrium photonic response. The results demonstrate that the BCP gels and their photonic effect provide a robust and visually interpretable method to differentiate different proteins.

  13. Hybrid particle-field molecular dynamics simulation for polyelectrolyte systems.

    Science.gov (United States)

    Zhu, You-Liang; Lu, Zhong-Yuan; Milano, Giuseppe; Shi, An-Chang; Sun, Zhao-Yan

    2016-04-14

    To achieve simulations on large spatial and temporal scales with high molecular chemical specificity, a hybrid particle-field method was proposed recently. This method is developed by combining molecular dynamics and self-consistent field theory (MD-SCF). The MD-SCF method has been validated by successfully predicting the experimentally observable properties of several systems. Here we propose an efficient scheme for the inclusion of electrostatic interactions in the MD-SCF framework. In this scheme, charged molecules are interacting with the external fields that are self-consistently determined from the charge densities. This method is validated by comparing the structural properties of polyelectrolytes in solution obtained from the MD-SCF and particle-based simulations. Moreover, taking PMMA-b-PEO and LiCF3SO3 as examples, the enhancement of immiscibility between the ion-dissolving block and the inert block by doping lithium salts into the copolymer is examined by using the MD-SCF method. By employing GPU-acceleration, the high performance of the MD-SCF method with explicit treatment of electrostatics facilitates the simulation study of many problems involving polyelectrolytes. PMID:27001709

  14. Responsive block copolymer photonics triggered by protein-polyelectrolyte coacervation.

    Science.gov (United States)

    Fan, Yin; Tang, Shengchang; Thomas, Edwin L; Olsen, Bradley D

    2014-11-25

    Ionic interactions between proteins and polyelectrolytes are demonstrated as a method to trigger responsive transitions in block copolymer (BCP) photonic gels containing one neutral hydrophobic block and one cationic hydrophilic block. Poly(2-vinylpyridine) (P2VP) blocks in lamellar poly(styrene-b-2-vinylpyridine) block copolymer thin films are quaternized with primary bromides to yield swollen gels that show strong reflectivity peaks in the visible range; exposure to aqueous solutions of various proteins alters the swelling ratios of the quaternized P2VP (QP2VP) gel layers in the PS-QP2VP materials due to the ionic interactions between proteins and the polyelectrolyte. Parameters such as charge density, hydrophobicity, and cross-link density of the QP2VP gel layers as well as the charge and size of the proteins play significant roles on the photonic responses of the BCP gels. Differences in the size and pH-dependent charge of proteins provide a basis for fingerprinting proteins based on their temporal and equilibrium photonic response. The results demonstrate that the BCP gels and their photonic effect provide a robust and visually interpretable method to differentiate different proteins. PMID:25393374

  15. Treatment of wastewater from a paint industry using polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Kori, M.M.; Gupta, S.K. [Indian Inst. of Tech., Bombay (India). Centre for Environmental Science and Engineering

    1994-12-31

    Eleven polyelectrolytes were tried separately to treat the wastewater from a paint manufacturing industry. Among these, Zetag 66, a cationic polyelectrolyte was found to be most effective. A dosage of 5 mg/L of this polyelectrolyte was found to be adequate to achieve 65% COD removal, 97% suspended solids removal, and 90% heavy metals removal. The use of this polyelectrolyte assumes significant importance as it eliminates the use of alum completely. This elimination of alum consumption results in considerable reduction of effluent treatment plant (ETP) sludge, which is a hazardous waste. The savings that results in the primary treatment is an added advantage.

  16. Novel formulations of vitamins and insulin by nanoengineering of polyelectrolyte multilayers around microcrystals.

    Science.gov (United States)

    Dai, Zhifei; Heilig, Anne; Zastrow, Heidi; Donath, Edwin; Möhwald, Helmuth

    2004-12-01

    Microcapsules loaded with vitamin K3 (VK3), biotin, or insulin were prepared by using a novel coating technology based on the layer-by-layer (LbL) deposition of oppositely charged polyelectrolytes onto microcrystal templates. This produced multilayered, polymeric shells of varying thickness around the crystalline cores. Dissolution of the core material (VK3 with ethanol, biotin with basic solution, and insulin with acidic solution), resulted in its release through the shells. Microelectrophoresis was employed to monitor the microcrystal coating process; confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) were used to verify multilayer coating and the formation of hollow polymer shells following removal of the microcrystal templates. The release rates of both VK3 and insulin decreased as the wall thickness (the number of polyelectrolyte layers deposited onto the microcrystal cores), increased. The release time could be varied by a factor of more than ten, depending on the number of polyelectrolyte layers applied. Following the addition of 70 mass % ethanol, the solubility of VK3 increased by as much as 170-fold, resulting in an increased rate of VK3 release. By selecting appropriate polymer materials for the shells, and by controlling the number of polyelectrolyte layers applied, shells of various thickness, stiffness, aqueous solubility, dispersibility, biocompatibility, and permeability can be constructed. PMID:15532049

  17. PREPARATION OF POLYELECTROLYTE MULTILAYER COATED MICROBUBBLES FOR USE AS ULTRASOUND CONTRAST AGENT

    Institute of Scientific and Technical Information of China (English)

    Zhan-wen Xing; Heng-te Ke; Shao-qin Liu; Zhi-fei Dai; Jin-rui Wang; Ji-bin Liu

    2008-01-01

    Objective To prepare and characterize polyelectrolyte multilayer film coated microbubbles for use as ultrasound contrast agent (UCA) and evaluate its effects in ultrasonic imaging on normal rabbit's fiver parenchyma.Methoda Pcrfluorocarbon (PFC)-containing microbubbles (ST68-PFC) were prepared by sonication based on surfactant ( Span 60 and Tween 80). Subsequently, the resulting ST68-PFC microbnbbles were coated using oppositely charged polyclectrolytes by microbubble-templated layer-by-layer self-assembly technique via electrostatic interaction.The enhancement effects in ultrasonic imaging on normal rabbit's liver parenchyma were assessed.Results The obtained microbubbles exhibited a narrow size distribution. The polyelectrolytes were successfully assembled onto the surface of ST68-PFC microbubbles. In vivo experiment showed that polyelectrolyte multilayer film coated UCA effectively enhanced the imaging of rabbit's liver parenchyma.Conclnsions The novel microbubbles UCA coated with polyelectrolyte multilayer, when enabled more function,has no obvious difference in enhancement effects compared with the pre-modified microbnbbles. The polymers with chemically active groups ( such as amino group and carboxyl group) can be used as the outermost layer for attachment of targeting ligands onto microbubbles, allowing selective targeting of the microbubbles to combine with desired sites.

  18. Cationic β-cyclodextrin polymer applied to a dual cyclodextrin polyelectrolyte multilayer system.

    Science.gov (United States)

    Junthip, Jatupol; Tabary, Nicolas; Leclercq, Laurent; Martel, Bernard

    2015-08-01

    A polyelectrolyte multilayer film (PEM) based on cationic and anionic β-cyclodextrin polyelectrolytes was coated onto a textile substrate for future drug delivery purposes. We firstly synthesized a novel cationic β-cyclodextrin polymer (polyEPG-CD) by crosslinking β-cyclodextrin (βCD) with epichlorohydrin (EP) under basic conditions, in the presence of glycidyltrimetrylammonium chloride (GTMAC) as cationizing group. The influence of preparation conditions has been investigated in order to preferably obtain a water soluble fraction whose charge density and molecular weights were optimal for the layer-by-layer (LbL) deposition process. The different cationic cyclodextrin polymers obtained were characterized by FTIR, NMR, colloidal titration, conductimetry, thermogravimetric analysis and size exclusion chromatography. Besides, the counterpart polyelectrolyte was a β-cyclodextrin polymer crosslinked with citric acid, polyCTR-CD, whose synthesis and characterization have been previously reported. Finally we realized the Layer by Layer (LbL) build-up of the PEM coating onto the textile support, using the dip coating method, by alternatively soaking it in cationic polyEPG-CD and anionic polyCTR-CD solutions. This multilayer self-assembly was monitored by SEM, gravimetry and OWLS in function of both polyelectrolytes concentrations and ratios. Solutions parameters such as pH, ionic strenght were also discussed.

  19. Reversible multi polyelectrolyte layers on gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Djoumessi Lekeufack, Diane; Brioude, Arnaud, E-mail: arnaud.brioude@univ-lyon1.fr [UMR CNRS 5615, Universite Claude Bernard Lyon 1, Laboratoire des Multimateriaux et Interfaces (LMI) (France); Lalatonne, Yoann; Motte, Laurence [UMR 7244 CNRS, Universite Paris 13, Laboratoire CSPBAT (France); Coleman, Anthony W.; Miele, Philippe [UMR CNRS 5615, Universite Claude Bernard Lyon 1, Laboratoire des Multimateriaux et Interfaces (LMI) (France)

    2012-06-15

    Gold nanoparticles surface can be easily modified by different molecules such as polyelectrolytes. In a typical multilayer system made of polyethyleneimine and poly(styrene sulfonate)sodium alternated layers around gold nanoparticles, we have evaluated the interactions between the different layers and the relative strength of interfacial properties. By means of UV-Visible and FTIR spectroscopies, we have shown that due to its amine functionalities, the bonding of polyethyleneimine to gold particles is stronger than the one implied with the sulfonate anion in the PSS inducing a clean removal of this latter after the last polyethyleneimine deposition. Considering that polyethyleneimine is cytotoxic and that only weak covalent bonds are concerned in polyelectrolyte multilayer, this last point is of main importance since external degradation thus exposing polyethyleneimine sub-layer of multilayer films to in vivo tissue cells can occur by many ways.

  20. Salt-induced aggregation of stiff polyelectrolytes

    International Nuclear Information System (INIS)

    Molecular dynamics simulation techniques are used to study the process of aggregation of highly charged stiff polyelectrolytes due to the presence of multivalent salt. The dominant kinetic mode of aggregation is found to be the case of one end of one polyelectrolyte meeting others at right angles, and the kinetic pathway to bundle formation is found to be similar to that of flocculation dynamics of colloids as described by Smoluchowski. The aggregation process is found to favor the formation of finite bundles of 10-11 filaments at long times. Comparing the distribution of the cluster sizes with the Smoluchowski formula suggests that the energy barrier for the aggregation process is negligible. Also, the formation of long-lived metastable structures with similarities to the raft-like structures of actin filaments is observed within a range of salt concentration.

  1. Scaling and Scale Breaking in Polyelectrolyte

    CERN Document Server

    Peterson, C; Söderberg, B; Peterson, Carsten; Sommelius, Ola

    1996-01-01

    We consider the thermodynamics of a uniformly charged polyelectrolyte with harmonic bonds. For such a system there is at high temperatures an approximate scaling of global properties like the end-to-end distance and the interaction energy with the chain-length divided by the temperature. This scaling is broken at low temperatures by the ultraviolet divergence of the Coulomb potential. By introducing a renormalization of the strength of the nearest- neighbour interaction the scaling is restored, making possible an efficient blocking method for emulating very large polyelectrolytes using small systems. The high temperature behaviour is well reproduced by the analytical high-$T$ expansions even for fairly low temperatures and system sizes. In addition, results from low-$T$ expansions, where the coefficients have been computed numerically, are presented. These results approximate well the corresponding Monte Carlo results at realistic temperatures. A corresponding analysis of screened chains is performed. The sit...

  2. On the effective charge of hydrophobic polyelectrolytes

    OpenAIRE

    Chepelianskii, Alexei; Mohammad-Rafiee, Farshid; Raphael, Elie

    2008-01-01

    In this paper we analyze the behavior of hydrophobic polyelectrolytes. It has been proposed that this system adopts a pearl-necklace structure reminiscent of the Rayleigh instability of a charged droplet. Using a Poisson-Boltzmann approach, we calculate the counterion distribution around a given pearl assuming the latter to be penetrable for the counterions. This allows us to calculate the effective electric charge of the pearl as a function of the chemical charge. Our predictions are in very...

  3. Swelling characteristics of acrylic acid polyelectrolyte hydrogel in a dc electric field

    Science.gov (United States)

    Jabbari, Esmaiel; Tavakoli, Javad; Sarvestani, Alireza S.

    2007-10-01

    A novel application of environmentally sensitive polyelectrolytes is in the fabrication of BioMEMS devices as sensors and actuators. Poly(acrylic acid) (PAA) gels are anionic polyelectrolyte networks that exhibit volume expansion in aqueous physiological environments. When an electric field is applied to PAA polyelectrolyte gels, the fixed anionic polyelectrolyte charges and the requirement of electro-neutrality in the network generate an osmotic pressure, above that in the absence of the electric field, to expand the network. The objective of this research was to investigate the effect of an externally applied dc electric field on the volume expansion of the PAA polyelectrolyte gel in a simulated physiological solution of phosphate buffer saline (PBS). For swelling studies in the electric field, two platinum-coated plates, as electrodes, were wrapped in a polyethylene sheet to protect the plates from corrosion and placed vertically in a vessel filled with PBS. The plates were placed on a rail such that the distance between the two plates could be adjusted. The PAA gel was synthesized by free radical crosslinking of acrylic acid monomer with ethylene glycol dimethacrylate (EGDMA) crosslinker. Our results demonstrate that volume expansion depends on the intensity of the electric field, the PAA network density, network homogeneity, and the position of the gel in the field relative to positive/negative electrodes. Our model predictions for PAA volume expansion, based on the dilute electrolyte concentration in the gel network, is in excellent agreement with the experimental findings in the high-electric-field regime (250-300 Newton/Coulomb).

  4. Hydrophobically modified polyelectrolytes synthesis, properties and interactions with surfactants.

    NARCIS (Netherlands)

    Nieuwkerk, A.C.

    1998-01-01

    Hydrophobically modified polyelectrolytes can form micelle-like aggregates, so-called microdomains, in aqueous solution. The hydrophobic side chains constitute the apolar inner part of these microdomains and the hydrophilic groups on the polyelectrolyte backbone are at the surface of the microdomain

  5. COMPARATIVE TOXICITY OF POLYELECTROLYTES TO SELECTED AQUATIC ANIMALS

    Science.gov (United States)

    Although polyelectrolytes are widely used to control solids in potable water and municipal wastewater, very few studies have been made to assess their toxicity to aquatic animals. Consequently, the authors tested the acute toxicity of several polyelectrolytes to rainbow trout, la...

  6. ANALYTICAL TECHNIQUES FOR POLYELECTROLYTES IN WASTEWATER: A REVIEW

    Science.gov (United States)

    Interest has been increasing regarding development of methods for the analysis of water soluble polyelectrolytes at trace levels in wastewater effluents and ambient waters. To that end a literature search was undertaken. The effort resulted in a total of 22 polyelectrolyte analyt...

  7. Advances in polyelectrolyte multilayer nanofilms as tunable drug delivery systems

    Directory of Open Access Journals (Sweden)

    Bingbing Jiang

    2009-08-01

    Full Text Available Bingbing Jiang1, John B Barnett2,3, Bingyun Li1,4,5#1Biomaterials, Bioengineering and Nanotechnology Laboratory, Department of Orthopaedics, School of Medicine, 2Department of Microbiology, Immunology, and Cell Biology, 3Center for Immunopathology and Microbial Pathogenesis, School of Medicine, 5Department of Chemical Engineering, College of Engineering and Mineral Resources, West Virginia University, Morgantown, WV, USA; 4WVNano Initiative, Morgantown, WV, USA; #Aided by a grant from Osteosynthesis and Trauma Care (OTC FoundationAbstract: There has been considerable interest in polyelectrolyte multilayer nanofilms, which have a variety of applications ranging from optical and electrochemical materials to biomedical devices. Polyelectrolyte multilayer nanofilms are constructed from aqueous solutions using electrostatic layer-by-layer self-assembly of oppositely-charged polyelectrolytes on a solid substrate. Multifunctional polyelectrolyte multilayer nanofilms have been studied using charged dyes, metal and inorganic nanoparticles, DNA, proteins, and viruses. In the past few years, there has been increasing attention to developing polyelectrolyte multilayer nanofilms as drug delivery vehicles. In this mini-review, we present recent developments in polyelectrolyte multilayer nanofilms with tunable drug delivery properties, with particular emphasis on the strategies in tuning the loading and release of drugs in polyelectrolyte multilayer nanofilms as well as their applications.Keywords: nanofilm, polyelectrolyte multilayer, drug delivery, electrostatic layer-by-layer self-assembly, biomedical device, surface modification

  8. Dynamics of ion exchange between self-assembled redox polyelectrolyte multilayer modified electrode and liquid electrolyte.

    Science.gov (United States)

    Grumelli, Doris E; Garay, Fernando; Barbero, Cesar A; Calvo, Ernesto J

    2006-08-10

    A probe beam deflection (PBD) study of ion exchange between an electroactive polymer poly(allylamine)-bipyridyl-pyridine osmium complex film and liquid electrolyte is reported. The PBD measurements were made simultaneously to chronoamperometric oxidation-reduction cycles, to be able to detect kinetic effects in the ion exchange. Layer-by-layer (LbL) self-assembled redox polyelectrolyte films with osmium bipyridyl complex covalently attached to poly(allylamine) (PAH-Os) and poly(styrene sulfonate) (PSS) have been built by alternate electrostatic adsorption from soluble polyelectrolytes. The ionic exchange during initial conditioning of the film ("break-in") undergoing oxidation-reduction cycles and recovery after equilibration in the reduced state have shown an exchange of anions and cations with time lag between them. The effect of the nature of cation on the ionic exchange has been investigated with dilute HCl, LiCl, NaCl, and CsCl electrolytes. The ratio of anion to cation exchanged at the film-electrolyte interface has a strong dependence on the nature of charge in the topmost layer, that is, when negatively charged PSS is the capping layer, a larger proportion of cation exchange is observed. This demonstrates that the electrical potential distribution at the redox polyelectrolyte multilayer (PEM)/electrolyte interface determines the ionic flux in response to charge injection in the film. PMID:16884254

  9. Layer-by-layer self-assembly of polyelectrolyte functionalized MoS2 nanosheets

    Science.gov (United States)

    Shen, Jianfeng; Pei, Yu; Dong, Pei; Ji, Jin; Cui, Zheng; Yuan, Junhua; Baines, Robert; Ajayan, Pulickel M.; Ye, Mingxin

    2016-05-01

    Few-layered polyelectrolyte functionalized MoS2 nanosheets were obtained for the first time through in situ polymerization of MoS2 nanosheets with poly(acrylic acid) and poly(acrylamide), both of which demonstrated excellent dispersibility and stability in water. After designing and optimizing the components of this series of polyelectrolyte functionalized MoS2 nanosheets, by exploiting the electrostatic interactions present in the modified MoS2 nanosheets, we further created a series of layer-by-layer (LBL) self-assembling MoS2-based films. To this end, uniform MoS2 nanosheet-based LBL films were precisely deposited on substrates such as quartz, silicon, and ITO. The polyelectrolyte functionalized MoS2 nanosheet assembled LBL film-modified electrodes demonstrated enhanced electrocatalytic activity for H2O2. As such, they are conducive to efficient sensors and advanced biosensing systems.Few-layered polyelectrolyte functionalized MoS2 nanosheets were obtained for the first time through in situ polymerization of MoS2 nanosheets with poly(acrylic acid) and poly(acrylamide), both of which demonstrated excellent dispersibility and stability in water. After designing and optimizing the components of this series of polyelectrolyte functionalized MoS2 nanosheets, by exploiting the electrostatic interactions present in the modified MoS2 nanosheets, we further created a series of layer-by-layer (LBL) self-assembling MoS2-based films. To this end, uniform MoS2 nanosheet-based LBL films were precisely deposited on substrates such as quartz, silicon, and ITO. The polyelectrolyte functionalized MoS2 nanosheet assembled LBL film-modified electrodes demonstrated enhanced electrocatalytic activity for H2O2. As such, they are conducive to efficient sensors and advanced biosensing systems. Electronic supplementary information (ESI) available: SEM, AFM and TEM characterization of PAA-MoS2 and PAM-MoS2 nanocomposites. More characterization and electrochemical properties of LBL films

  10. Polyelectrolyte decomplexation via addition of salt: charge correlation driven zipper.

    Science.gov (United States)

    Antila, Hanne S; Sammalkorpi, Maria

    2014-03-20

    We report the first atomic scale studies of polyelectrolyte decomplexation. The complex between DNA and polylysine is shown to destabilize and spontaneously open in a gradual, reversible zipper-like mechanism driven by an increase in solution salt concentration. Divalent CaCl2 is significantly more effective than monovalent NaCl in destabilizing the complex due to charge correlations and water binding capability. The dissociation occurs accompanied by charge reversal in which charge correlations and ion binding chemistry play a key role. Our results are in agreement with experimental work on complex dissociation but in addition show the underlying microstructural correlations driving the behavior. Comparison of our full atomic level detail and dynamics results with theoretical works describing the PEs as charged, rigid rods reveals that although charge correlation involved theories provide qualitatively similar responses, considering also specific molecular chemistry and molecular level water contributions provides a more complete understanding of PE complex stability and dynamics. The findings may facilitate controlled release in gene delivery and more in general tuning of PE membrane permeability and mechanical characteristics through ionic strength.

  11. Polyelectrolyte decomplexation via addition of salt: charge correlation driven zipper.

    Science.gov (United States)

    Antila, Hanne S; Sammalkorpi, Maria

    2014-03-20

    We report the first atomic scale studies of polyelectrolyte decomplexation. The complex between DNA and polylysine is shown to destabilize and spontaneously open in a gradual, reversible zipper-like mechanism driven by an increase in solution salt concentration. Divalent CaCl2 is significantly more effective than monovalent NaCl in destabilizing the complex due to charge correlations and water binding capability. The dissociation occurs accompanied by charge reversal in which charge correlations and ion binding chemistry play a key role. Our results are in agreement with experimental work on complex dissociation but in addition show the underlying microstructural correlations driving the behavior. Comparison of our full atomic level detail and dynamics results with theoretical works describing the PEs as charged, rigid rods reveals that although charge correlation involved theories provide qualitatively similar responses, considering also specific molecular chemistry and molecular level water contributions provides a more complete understanding of PE complex stability and dynamics. The findings may facilitate controlled release in gene delivery and more in general tuning of PE membrane permeability and mechanical characteristics through ionic strength. PMID:24559400

  12. Characterization of polyelectrolyte behavior of the polysaccharides chitosan, heparin, and hyaluronan, by light scattering and viscometry.

    Science.gov (United States)

    Boddohi, Soheil; Yonemura, Susan; Kipper, Matt

    2008-03-01

    This study on the polyelectrolyte behavior of polysaccharides in solution is motivated by our recent work in development of nanostructured polysaccharide-based surface coatings. Chitosan behaves as a weak polycation, and hyaluronan behaves as a weak polyanion, while heparin behaves as a strong polyanion. The ability to control the conformation of these polysaccharides in solution, by changing the solution ionic strength and pH may offer the opportunity to further tune the nanoscale features of polysaccharide-based surface coatings assembled from solution. In the work reported here, the solution conformation of these polymers is determined from gel permeation chromatography coupled to differential refractive index, light scattering, and viscometry detection. These results are related to the nanostructure of chitosan-heparin and chitosan-hyaluronan surface coatings based on polyelectrolyte multilayers.

  13. Interactions between hairy rod anionic conjugated polyelectrolytes and nonionic alkyloxyethylene surfactants in aqueous solution: Observations from cloud point behaviour

    OpenAIRE

    Fonseca, Sofia M.; Eusébio, M. Ermelinda; Castro, Ricardo; Burrows, Hugh D.; Tapia, Maria José; Olsson, Ulf

    2007-01-01

    The effect of three anionic, hairy-rod fluorene based conjugated polyelectrolytes on the cloud points of the alkyloxyethylene surfactants C10E3, C12E4, C12E5, and C12E6 has been studied in aqueous solution. Although the association behaviour of these rigid polymers with surfactants is different from that of more flexible polyelectrolytes, both types of polymers are seen to increase the cloud points, probably as a consequence of associative interactions. The possible importance of Coulombic in...

  14. Study of Physical and Colloid-Chemical Properties of Acrylic Polyelectrolytes of “M-PAA” Series and Their Modification

    Directory of Open Access Journals (Sweden)

    N.O Dzhakipbekova

    2015-12-01

    Full Text Available The aim of this study is to search for the best basic technology to replace the base in the metallization of dielectrics. We studied conducting polymers – acrylic polyelectrolytes. Polyelectrolytes include high molecular weight compounds containing macromolecules and ionogenic groups. Experimental studies have shown that the rational use of HSP for the regulation of colloid-chemical processes in the production should take into account the functional structure of the polymer, its conformational state of macromolecules in solution, the degree of association, dissociation of functional groups, and other factors, which necessitates studying the physical and colloidal chemical characteristics of HSP solutions depending on the concentration.

  15. Investigating forces between charged particles in the presence of oppositely charged polyelectrolytes with the multi-particle colloidal probe technique.

    Science.gov (United States)

    Borkovec, Michal; Szilagyi, Istvan; Popa, Ionel; Finessi, Marco; Sinha, Prashant; Maroni, Plinio; Papastavrou, Georg

    2012-11-01

    Direct force measurements are used to obtain a comprehensive picture of interaction forces acting between charged colloidal particles in the presence of oppositely charged polyelectrolytes. These measurements are achieved by the multi-particle colloidal probe technique based on the atomic force microscope (AFM). This novel extension of the classical colloidal probe technique offers three main advantages. First, the technique works in a colloidal suspension with a huge internal surface area of several square meters, which simplifies the precise dosing of the small amounts of the polyelectrolytes needed and makes this approach less sensitive to impurities. Second, the particles are attached in-situ within the fluid cell, which avoids the formation of nanobubbles on the latex particles used. Third, forces between two similar particles from the same batch are being measured, which allows an unambiguous determination of the surface potential due to the symmetry of the system. Based on such direct force measurements involving positively and negatively charged latex particles and different polyelectrolytes, we find the following forces to be relevant. Repulsive electrostatic double-layer forces and attractive van der Waals forces as described by the theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO) are both important in these systems, whereby the electrostatic forces dominate away from the isoelectric point (IEP), while at this point they vanish. Additional non-DLVO attractive forces are operational, and they have been identified to originate from the electrostatic interactions between the patch-charge heterogeneities of the adsorbed polyelectrolyte films. Highly charged polyelectrolytes induce strong patch-charge attractions, which become especially important at low ionic strengths and high molecular mass. More weakly charged polyelectrolytes seem to form more homogeneous films, whereby patch-charge attractions may become negligible. Individual bridging events

  16. Interpretation with a Donnan-based concept of the influence of simple salt concentration on the apparent binding of divalent ions to the polyelectrolytes polystyrenesulfonate and dextran sulfate

    Science.gov (United States)

    Marinsky, J.A.; Baldwin, Robert F.; Reddy, M.M.

    1985-01-01

    It has been shown that the apparent enhancement of divalent metal ion binding to polyions such as polystyrenesulfonate (PSS) and dextran sulfate (DS) by decreasing the ionic strength of these mixed counterion systems (M2+, M+, X-, polyion) can be anticipated with the Donnan-based model developed by one of us (J.A.M.). Ion-exchange distribution methods have been employed to measure the removal by the polyion of trace divalent metal ion from simple salt (NaClO4)-polyion (NaPSS) mixtures. These data and polyion interaction data published earlier by Mattai and Kwak for the mixed counterion systems MgCl2-LiCl-DS and MgCl2-CsCl-DS have been shown to be amenable to rather precise analysis by this model. ?? 1985 American Chemical Society.

  17. Polyelectrolytes-promoted Forward Osmosis Processes

    KAUST Repository

    Ge, Q.C.

    2012-11-07

    The development of the forward osmosis (FO) process has been constrained by the slow development of appropriate draw solutions. Two significant concerns related to draw solutions are the draw solute leakage and intensive-energy requirement in recycling draw solutes after the FO process. FO would be much attractive if there is no draw solute leakage and the recycle of draw solutes is easy and economic.In this study, polyelectrolytes of a series of polyacrylic acid sodium salts (PAA-Na), were explored as draw solutes in the FO process. The characteristics of high solubility in water and flexibility in structural configuration ensure the suitability of PAA-Na as draw solutes and their relative ease in recycle through pressure-driven ultrafiltration (UF) membrane processes. The high water flux with insignificant salt leakage in the FO process and the high salt rejection in UF recycle processes reveal the superiority of PAA-Na to conventional ionic salts, such as NaCl, when comparing their FO performance via the same membranes. The repeatable performance of PAA-Na after recycle indicates the absence of any aggregation problems. The overall performance demonstrates that polyelectrolytes of PAA-Na series are promising as draw solutes, and the new concept of using polyelectrolytes as draw solutes in FO processes is applicable. The magnetic nanoparticle draw solutes can generate reasonably high osmotic pressure in FO system due to the functional groups on the nanoparticles surface and they can be regenerated through magnetic field and reused as draw solutes. Thermo-responsive magnetic nanoparticles are able to be regenerated with high efficiency as the thermo-responsive property can assist the regeneration in a low-strength magnetic field.

  18. Molecular base of biochemical complex I deficiency.

    NARCIS (Netherlands)

    Hoefs, S.J.G.; Rodenburg, R.J.T.; Smeitink, J.A.M.; Heuvel, L.P.W.J. van den

    2012-01-01

    The oxidative phosphorylation (OXPHOS) system, consisting of five enzyme complexes (I-V) together with 2 electron carriers, has an important role in the energy metabolism of the cell. With 45 subunits, complex I is the first and largest complex of the respiratory chain. It is under bigenomic control

  19. Chain Collapse and Counterion Condensation in Dilute Polyelectrolyte Solutions

    OpenAIRE

    Brilliantov, N. V.; Kuznetsov, D. V.; Klein, R.

    1998-01-01

    A new quantitative theory for polyelectrolytes in salt free dilute solutions is developed. Depending on the electrostatic interaction strength, polyelectrolytes in solutions can undergo strong stretching (with polyelectrolyte dimension R_g\\sim l_B^{1/3}N, where l_B is the Bjerrum length and N is the number of the chain segments) or strong compression (with R_g\\sim l_B^{-1/2}N^{1/3}). A strong polymer collapse occurs as a first-order phase transition due to accompanying counterion condensation.

  20. Investigation of multilayered polyelectrolyte thin films by means of refractive index measurements, FT-IR spectroscopy and SEM

    Science.gov (United States)

    Bodurov, I.; Vlaeva, I.; Exner, G.; Uzunova, Y.; Russev, S.; Pilicheva, B.; Viraneva, A.; Yovcheva, T.; Grancharova, Ts; Sotirov, S.; Marudova, M.

    2016-02-01

    Multilayered polyelectrolyte films are promising structures in the biomedical field. In order to meet the demands for biomedical applications, the structures have to be built from biocompatible and/or biodegradable, nontoxic starting materials, possessing some specific functional properties, depending on the particular application. In the present study, the multilayered polyelectrolyte films with potential use as buccal bioadhesive drug delivery systems were investigated. They were prepared via layer-by-layer deposition of successive nanolayers onto substrate. Three different biopolymers were used. The substrate, from poly(lactic acid), was solvent casted. After that, it was subjected to corona treatment, which ensures surface charge excess for the multilayer deposition. The nanolayers were prepared either from 0.01 g/L solutions of chitosan or 0.05 g/L xanthan. Acetate buffer (pH 4.5 and ionic strength 1 M) was used as a solvent. The substrate was dipped successively into one of the solutions, allowing formation of polyelectrolyte complexes of chitosan (polycation) and xanthan (polyanion). The substrates was treated in negative corona. The multilayered structures consisted of 8, 9, 14, 15 or 20 nanolayers. Number of techniques, such refractive index measurements, FT- IR spectroscopy and SEM morphology were employed in order to monitor the properties of the so prepared multilayered polyelectrolyte films.

  1. Ratiometric fluorescent ion detection in water with high sensitivity via aggregation-mediated fluorescence resonance energy transfer using a conjugated polyelectrolyte as an optical platform.

    Science.gov (United States)

    Le, Van Sang; Kim, Boram; Lee, Wonho; Jeong, Ji-Eun; Yang, Renqiang; Woo, Han Young

    2013-05-14

    A cationic conjugated polyelectrolyte was designed and synthesized based on poly(fluorene-co-phenylene) containing 5 mol% benzothiadiazole (BT) as a low energy trap and 15-crown-5 as a recognizing group for potassium ions. A potassium ion can form a sandwich-type 2:1 Lewis acid-based complex with 15-crown-5, to cause the intermolecular aggregation of polymers. This facilitates inter-chain fluorescence resonance energy transfer (FRET) to a low-energy BT segment, resulting in fluorescent signal amplification, even at dilute analyte concentrations. Highly sensitive and selective detection of K(+) ions was demonstrated in water. The linear response of ratiometric fluorescent signal as a function of [K(+) ] allows K(+) quantification in a range of nanomolar concentrations with a detection limit of ≈0.7 × 10(-9) M. PMID:23417971

  2. Interest of Polyelectrolyte Multilayer thin Films in Tissue Engineering:Application to Vascular Allograft

    Institute of Scientific and Technical Information of China (English)

    Halima KERDJOUDJ; Cedric BOURA; Vanessa MOBY; Dominique DUMAS; Luc MARCHAL; Jean-Claude VOEGEL; Jean-Fran(c)ois STOLTZ; Patrick MENU

    2005-01-01

    @@ 1 Introduction Obstructive atherosclerosis vascular disease remains one of the greatest public health threats in the world. Surgical treatment to replace diseased blood vessels is usually done using major human allografts (veins or arteries) or synthetic prosthesis ( PTFE, Dacron). However, these substitutes have not a good pateney, because of the lack of endothelial cells (ECs) layer, which prevents thrombus formation. The challenge of tissue engineering vessels is to build-up blood/substitute interface near native vessels.In order to improve ECs adhesion, it is necessary to precoat the intra-luminal vessel. Recently, a new surface modification technique arose, based on the alternate adsorption of oppositely charged polyelectrolytes. Our objective was to favour the endothelialization of the cryo-preserved allografts, treated with a thin polyelectrolyte multilayered film, made of PSS (poly (sodium-4-styrenesulfonate) ) or PAH (poly (allylamine hydrochloride) ).

  3. Coronene-based charge-transfer complexes.

    Science.gov (United States)

    Yoshida, Yukihiro; Isomura, Kazuhide; Kumagai, Yoshihide; Maesato, Mitsuhiko; Kishida, Hideo; Mizuno, Motohiro; Saito, Gunzi

    2016-08-01

    Recent developments in the arena of charge-transfer complexes composed of the D 6h-symmetric polycyclic aromatic hydrocarbon, coronene, are highlighted with emphasis on the structural and physical properties of these complexes. Because of the dual electron-donating and -accepting abilities of coronene, this group involves structurally-defined four cation salts and three anion salts. The Jahn-Teller distortions and in-plane motion of coronene molecules in the solids, both of which are closely associated with the high symmetry of coronene molecules, and syntheses of clathrate-type complexes are also presented. PMID:27294380

  4. IONIC SELF-ASSEMBLY AND HUMIDITY SENSITIVITY OF POLYELECTROLYTE MULTILAYERS

    Institute of Scientific and Technical Information of China (English)

    Hai-hu Yu; De-sheng Jiang

    2002-01-01

    Multilayer thin films of alternately adsorbed layers of polyelectrolytes PDDA and PS-119 were formed on both planar silica substrates and optical fibers through the ionic self-assembly technique. Intrinsic Fabry-Perot cavities were fabricated by stepwise assembling the polyelectrolytes onto the ends of optical fibers for the purposes of fiber optical device and sensor development. Ionically assembled polyelectrolyte multilayer thin films, in whichthere are hydrophilic side groups with strong affinity towards water molecules, are a category of humidity-sensitive functional materials. The polyelectrolyte multilayer thin film Fabry-Perot cavity-type fiber optical humidity sensor can work over a wide range from about 0% RH to about 100% RH with a response time less than 1 s.

  5. Boroxine ring compounds as dissociation enhancers in gel polyelectrolytes

    International Nuclear Information System (INIS)

    In order to combine the advantages of both traditional gel electrolytes and polyelectrolytes, a novel polyelectrolyte which incorporates a boroxine ring-containing anion-trapping agent has been explored. Poly(lithium 2-acrylamido-2-methyl-1-propanesulfonate) (PAMPSLi), ethylene carbonate (EC) and tri(methoxyethoxyethoxyethoxy)boroxine (TME3Bx) were combined to prepare various gel systems. The thermal properties and conductivities of these gels have been investigated. A conductivity of 10-3.6 S cm-1 at 20 deg. C has been achieved in a gel polyelectrolyte system with a molar ratio of [EC]:[TME3Bx]:[Li+]=24:1.7:1. Temperature-dependent NMR measurements indicated that a significant interaction exists between the boroxine ring and the polyelectrolyte

  6. Polyelectrolytes polarization in non-uniform electric fields

    OpenAIRE

    Farahpour, Farnoush; Varnik, Fathollah; Ejtehadi, Mohammad Reza

    2014-01-01

    Stretching dynamics of polymers in microfluidics is of particular interest for polymer scientists. As a charged polymer, a polyelectrolyte can be deformed from its coiled equilibrium configuration to an extended chain by applying uniform or non-uniform electric fields. By means of hybrid lattice Boltzmann-molecular dynamics simulations, we investigate how the condensed counterions around the polyelectrolyte contribute to the polymer stretching in inhomogeneous fields. As an application, we di...

  7. Anisotropic Diffusion of Polyelectrolyte Chains within Multi-layer Films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Li [Stevens Institute of Technology, Hoboken, New Jersey; Kozlovskaya, Veronika [University of Alabama, Birmingham; Kharlampieva, Eugenia [University of Alabama, Birmingham; Ankner, John Francis [ORNL; Sukhishvili, Prof. Svetlana A. [Stevens Institute of Technology, Hoboken, New Jersey

    2012-01-01

    We found diffusion of polyelectrolyte chains within multilayer films to be highly anisotropic, with the preferential chain motion parallel to the substrate. The degree of anisotropy was quantified by a combination of fluorescence recovery after photobleaching and neutron reflectometry, probing chain diffusion in directions parallel and perpendicular to the substrate, respectively. Chain mobility was controlled by ionic strength of annealing solutions and steric hindrance to ionic pairing of interacting polyelectrolytes.

  8. Tailoring fibre and paper properties using physical adsorption of polyelectrolytes

    OpenAIRE

    Marais, Andrew

    2012-01-01

    The adsorption of polyelectrolytes, both as monolayers and as multilayers, was investigated as an easy and non-expensive way of producing lignocellulosic fibrous materials with enhanced mechanical properties. In the first part of the work described in this thesis, the adsorption of a polyelectrolyte monolayer onto the surface of unbleached and unbeaten kraft pulp fibres with different kappa numbers was investigated. Adsorption isotherms were obtained in order to determine the amounts of polym...

  9. Interaction forces between surfaces coated with highly branched polyelectrolytes

    OpenAIRE

    Pericet-Cámara, Ramón; Borkovec, Michal

    2007-01-01

    In this thesis, interactions between surfaces with adsorbed highly branched polyelectrolytes were studied with the colloidal probe technique. By studying the adsorption behavior of highly branched polyelectrolytes, the lateral distribution of the surface charge could be tuned by the appropriate adsorption conditions. By choosing different polyelecrtrolytes, namely highly branched poly(ethylenimine) (PEI) and poly(amido amine) (PAMAM) dendrimers, it was possible to investigate the forces betwe...

  10. Adsorption of polyelectrolytes on silica and gold surfaces

    OpenAIRE

    Altamirano, M. A. Balderas; Camacho, R.; E. Pérez; Goicochea, A. Gama

    2016-01-01

    The results of a study that helps understand the mechanisms of adsorption of polyelectrolytes on particles, using numerical simulation methods, specifically the one known as dissipative particle dynamics are reported here. The adsorption of cationic polyelectrolytes of two different polymerization degrees interacting with two types of surfaces, one made of gold and the other of silica is predicted and compared. We find that a more negatively charged wall does not necessarily adsorb more catio...

  11. Effect of cationic polyelectrolytes addition in cement cohesion

    OpenAIRE

    Edison Albert Zuluaga-Hernández; Bibian A Hoyos

    2014-01-01

    Here is studied the variation in cohesion of cement main phase (C-S-H) as a result of cationic polyelectrolytes addition (quaternary amines spermine and norspermidine). Cohesion study was carried out by molecular simulation techniques (Monte Carlo) using a primitive model in a canonical ensemble (NVT). The proposed model takes into account the influence of ionic size of each particle and the addition of polyelectrolytes with different charge number and separation. The results obtained show th...

  12. Interaction forces between surfaces coated with highly branched polyelectrolytes

    OpenAIRE

    Pericet-Cámara, Ramón

    2006-01-01

    In this thesis, interactions between surfaces with adsorbed highly branched polyelectrolytes were studied with the colloidal probe technique. By studying the adsorption behavior of highly branched polyelectrolytes, the lateral distribution of the surface charge could be tuned by the appropriate adsorption conditions. By choosing different polyelecrtrolytes, namely highly branched poly(ethylenimine) (PEI) and poly(amido amine) (PAMAM) dendrimers, it was possible to investigate the forces betwe...

  13. Evaluation of shape complexity based on STL data

    OpenAIRE

    B. Valentan; T. Brajlih; I. Drstvensek; J. Balic

    2006-01-01

    Purpose: Purpose of this paper is to present a part complexity, based on basic information of the STL data.Design/methodology/approach: This paper presents a few methods of evaluating the complexity of the shape, based on the parts STL data. Methods vary from very simple based on the number of triangles in STL file and the parts volume, to the more complex mathematical determination based on the relations of the basic STL data.Findings: We discovered that evaluation of shape complexity based ...

  14. Preferential enhancement of reverse dermal Arthus reaction by polyelectrolytes: in vivo and in vitro evidence for mediation by oxygen-derived radicals and their metabolites

    International Nuclear Information System (INIS)

    The ability of cationic and anionic polyelectrolytes (polyhistidine, histone, poly-arginine and polyanetholsulfonate) to modulate an acute immune complex (IgG-BSA) mediated inflammatory response was studied. Tissue injury elicited in rats by the reverse dermal Arthus reaction was increased 20-60% by complexing the antibody and polyelectrolye prior to intradermal injection. Intravenous administration of polyethylene glycol-coupled (PEG) superoxide dismutase (4125 U) produced a 30-70% suppression of this tissue injury. PEG-catalase (2000 U) had no suppressive effect. Concomitant in vitro functional studies (enzyme release, O2- and H2O2 generation and chemiluminescence) of rat neutrophils stimulated with preformed immune complexes modified with polyelectrolytes demonstrated 2-fold increase in O2- generation, modest increases in H2O2 generation and large increases in chemiluminescence. There was no change in enzyme (β-glucuronidase) secretion. The polyelectrolytes employed in this study did not alter the capacity of preformed IgG-BSA complexes to fix complement. These studies suggest that immune complexes modified with either cationic or anionic polyelectrolytes have increased phlogistic potential that is at least in part mediated by enhanced generation of oxygen-derived metabolites and not by increased enzyme secretion or by increased fixation of complement

  15. Polyelectrolyte-versus membrane-coated electrodes for energy production by capmix salinity exchange methods

    Science.gov (United States)

    Fernández, M. M.; Wagterveld, R. M.; Ahualli, S.; Liu, F.; Delgado, A. V.; Hamelers, H. V. M.

    2016-01-01

    In this paper we analyze the energy and power achievable by means of a recently proposed salinity gradient technique for energy production. The method, denominated soft electrode or SE, is based on the potential difference that can be generated between two porous electrodes coated with cationic and anionic polyelectrolytes. It is related to the Capacitive Donnan Potential (CDP) technique, where the electrical potential variations are mostly related to the Donnan potential, of ion-selective membranes in the case of CDP, and of the polyelectrolyte coating in SE. It is found that although SE is comparable to CDP in terms of energy production, it presents slower rates of voltage change, and lower achieved power. The separate analysis of the response of positively and negatively coated electrodes shows that the latter produces most of the voltage rise and also of the response delay. These results, together with electrokinetic techniques, give an idea on how the two types of polyelectrolytes adsorb on the carbon surface and affect differently the diffusion layer. It is possible to suggest that the SE technique is a promising one, and it may overcome the drawbacks associated to the use of membranes in CDP.

  16. Electrophoresis of a polyelectrolyte through a nanopore

    CERN Document Server

    Ghosal, S

    2006-01-01

    A hydrodynamic model for determining the electrophoretic speed of a polyelectrolyte through a nanopore is presented. It is assumed that the speed is determined by a balance of electrical and viscous forces arising from within the pore and that classical continuum electrostatics and hydrodynamics may be considered applicable. An explicit formula for the translocation speed as a function of the pore geometry and other physical parameters is obtained and is shown to be consistent with experimental measurements on DNA translocation through nanopores in silicon membranes. Experiments also show a weak dependence of the translocation speed on polymer length that is not accounted for by the present model. It is hypothesized that this is due to secondary effects that are neglected here.

  17. The influence of charged-induced variations in the local permittivity on the static and dynamic properties of polyelectrolyte solutions

    Science.gov (United States)

    Fahrenberger, Florian; Hickey, Owen A.; Smiatek, Jens; Holm, Christian

    2015-12-01

    There is a large body of literature investigating the static and dynamic properties of polyelectrolytes due both to their widespread application in industrial processes and their ubiquitous presence in biology. Because of their highly charged nature, polyelectrolytes tend to alter the local dielectric permittivity of the solution within a few nanometers of their backbone. This effect has, however, been almost entirely ignored in both simulations and theoretical work. In this article, we apply our recently developed electrostatic solver based on Maxwell's equations to examine the effects of the permittivity reduction in the vicinity of the polyelectrolyte. We first verify our new approach by calculating and comparing ion distributions around a linear fixed polyelectrolyte and find both quantitative and qualitative changes in the ion distribution. Further simulations with an applied electric field show that the reduction in the local dielectric constant increases the mobility of the chains by approximately ten percent. More importantly, variations in the local dielectric constant lead to qualitatively different behavior of the conductivity.

  18. Layer-by-layer deposition of oppositely charged polyelectrolytes on the surface of condensed DNA particles.

    Science.gov (United States)

    Trubetskoy, V S; Loomis, A; Hagstrom, J E; Budker, V G; Wolff, J A

    1999-08-01

    DNA can be condensed with an excess of poly-cations in aqueous solutions forming stable particles of submicron size with positive surface charge. This charge surplus can be used to deposit alternating layers of polyanions and polycations on the surface surrounding the core of condensed DNA. Using poly-L-lysine (PLL) and succinylated PLL (SPLL) as polycation and polyanion, respectively, we demonstrated layer-by-layer architecture of the particles. Polyanions with a shorter carboxyl/backbone distance tend to disassemble binary DNA/PLL complexes by displacing DNA while polyanions with a longer carboxyl/backbone distance effectively formed a tertiary complex. The zeta potential of such complexes became negative, indicating effective surface recharging. The charge stoichiometry of the DNA/PLL/SPLL complex was found to be close to 1:1:1, resembling poly-electrolyte complexes layered on macrosurfaces. Recharged particles containing condensed plasmid DNA may find applications as non-viral gene delivery vectors.

  19. Adsorption of a synthetic heparinoid polyelectrolyte on an ion-exchanging surface

    NARCIS (Netherlands)

    Froehling, Peter E.; Bantjes, Adriaan; Kolar, Z.

    1977-01-01

    The adsorption of a synthetic heparinoid polyelectrolyte on poly(vinylchloride) previously treated with tridodecylmethylammonium chloride (TDMAC) was studied using radiotracer techniques to provide a more quantitative picture of antithrombogenic surface coatings. 125I-labeled polyelectrolyte was use

  20. A Complexity measure based on Requirement Engineering Document

    CERN Document Server

    Sharma, Ashish

    2010-01-01

    Research shows, that the major issue in development of quality software is precise estimation. Further this estimation depends upon the degree of intricacy inherent in the software i.e. complexity. This paper attempts to empirically demonstrate the proposed complexity which is based on IEEE Requirement Engineering document. It is said that a high quality SRS is pre requisite for high quality software. Requirement Engineering document (SRS) is a specification for a particular software product, program or set of program that performs some certain functions for a specific environment. The various complexity measure given so far are based on Code and Cognitive metrics value of software, which are code based. So these metrics provide no leverage to the developer of the code. Considering the shortcoming of code based approaches, the proposed approach identifies complexity of software immediately after freezing the requirement in SDLC process. The proposed complexity measure compares well with established complexity...

  1. Capturing Complex Multidimensional Data in Location-Based Data Warehouses

    DEFF Research Database (Denmark)

    Timko, Igor; Pedersen, Torben Bach

    2004-01-01

    Motivated by the increasing need to handle complex multidimensional data inlocation-based data warehouses, this paper proposes apowerful data model that is able to capture the complexities of such data. The model provides a foundation for handling complex transportationinfrastructures and the att...... and the attached static and dynamic content,and performing queries on this data. The model is motivated with a comprehensive real-world case study, basedon our collaboration with a leading Danish vendor of location-based services....

  2. Multilayered Polyelectrolyte Films:A Tool for Biomaterial Coatings and Tissue Engineering?

    Institute of Scientific and Technical Information of China (English)

    Jean-Claude; VOEGEL; Joёlle; OGIER; Catherine; PICART; Nadia; JESSEL; Philippe; LAVALLE; Vincent; BALL; Bernard; SENGER; Pierre; SCHAAF

    2005-01-01

    1 Physicochemical aspects of multilayered polyelectrolyte films Multilayered polyelectrolyte films are obtained by alternated depositions on a solid surface of polyanions and polycations~([1]). The driving force for the build-up results from the charge excess which appears on the top of the film after each new polyelectrolyte adsorption. The film top becomes thus positively (respectively negatively) charged when the film is ending by a polycation (respectively polyanion). Various polyelectrolyte systems hav...

  3. Proton and metal ion binding to natural organic polyelectrolytes-II. Preliminary investigation with a peat and a humic acid

    Science.gov (United States)

    Marinsky, J.A.; Reddy, M.M.

    1984-01-01

    We summarize here experimental studies of proton and metal ion binding to a peat and a humic acid. Data analysis is based on a unified physico-chemical model for reaction of simple ions with polyelectrolytes employing a modified Henderson-Hasselbalch equation. Peat exhibited an apparent intrinsic acid dissociation constant of 10-4.05, and an apparent intrinsic metal ion binding constant of: 400 for cadmium ion; 600 for zinc ion; 4000 for copper ion; 20000 for lead ion. A humic acid was found to have an apparent intrinsic proton binding constant of 10-2.6. Copper ion binding to this humic acid sample occurred at two types of sites. The first site exhibited reaction characteristics which were independent of solution pH and required the interaction of two ligands on the humic acid matrix to simultaneously complex with each copper ion. The second complex species is assumed to be a simple monodentate copper ion-carboxylate species with a stability constant of 18. ?? 1984.

  4. Complex System Optimization Using Biogeography-Based Optimization

    Directory of Open Access Journals (Sweden)

    Dawei Du

    2013-01-01

    Full Text Available Complex systems are frequently found in modern industry. But with their multisubsystems, multiobjectives, and multiconstraints, the optimization of complex systems is extremely hard. In this paper, a new algorithm adapted from biogeography-based optimization (BBO is introduced for complex system optimization. BBO/Complex is the combination of BBO with a multiobjective ranking system, an innovative migration approach, and effective diversity control. Based on comparisons with three complex system optimization algorithms (multidisciplinary feasible (MDF, individual discipline feasible (IDF, and collaborative optimization (CO on four real-world benchmark problems, BBO/Complex demonstrates competitive performance. BBO/Complex provides the best performance in three of the benchmark problems and the second best in the fourth problem.

  5. Multifunctional polyelectrolyte multilayers as nanofiltration membranes and as sacrificial layers for easy membrane cleaning

    NARCIS (Netherlands)

    Ilyas, Shazia; Grooth, de Joris; Nijmeijer, Kitty; Vos, de Wiebe M.

    2015-01-01

    This manuscript investigates the modification of an ultra-filtration (UF) membrane support with polyelectrolyte multilayers (PEMs) consisting of the weak polyelectrolytes poly(allyl amine) hydrochloride (PAH) and poly(acrylic acid) (PAA). These prepared polyelectrolyte multilayer membranes have a du

  6. Coacervation in Symmetric Mixtures of Oppositely Charged Rodlike Polyelectrolytes

    Science.gov (United States)

    Kumar, Rajeev; Fredrickson, Glenn

    2010-03-01

    Phase separation in the salt-free symmetric mixtures of oppositely charged rodlike polyelectrolytes is studied using quasi-analytical calculations. Stability analyses for the isotropic-isotropic and the isotropic-nematic phase transitions in the symmetric mixtures are carried out. It is shown that electrostatics favor nematic ordering. Also, the coexistence curves for the symmetric mixtures are computed, and the effects of the linear charge density and the electrostatic interaction strength on the phase boundaries are studied. It is found that the counterions are uniformly distributed in the coexisting phases for low electrostatic interaction strengths characterized by the linear charge density of the polyelectrolytes and the Bjerrum's length. However, the counterions also phase separate along with the rodlike polyelectrolytes with an increase in the electrostatic interaction strength. It is shown that the number density of the counterions is higher in the concentrated (or coacervate) phase than in the dilute (or supernatant) phase. In contrast to the rodlike mixtures, flexible polyelectrolyte mixtures can undergo only isotropic-isotropic phase separation. A comparison of the coexistence curves for the weakly charged rodlike with the flexible polyelectrolyte mixtures reveals that the electrostatic driving force for the isotropic-isotropic phase separation is stronger in the flexible mixtures.

  7. Salt Effect on Osmotic Pressure of Polyelectrolyte Solutions: Simulation Study

    Directory of Open Access Journals (Sweden)

    Jan-Michael Y. Carrillo

    2014-07-01

    Full Text Available Abstract: We present results of the hybrid Monte Carlo/molecular dynamics simulations of the osmotic pressure of salt solutions of polyelectrolytes. In our simulations, we used a coarse-grained representation of polyelectrolyte chains, counterions and salt ions. During simulation runs, we alternate Monte Carlo and molecular dynamics simulation steps. Monte Carlo steps were used to perform small ion exchange between simulation box containing salt ions (salt reservoir and simulation box with polyelectrolyte chains, counterions and salt ions (polyelectrolyte solution. This allowed us to model Donnan equilibrium and partitioning of salt and counterions across membrane impermeable to polyelectrolyte chains. Our simulations have shown that the main contribution to the system osmotic pressure is due to salt ions and osmotically active counterions. The fraction of the condensed (osmotically inactive counterions first increases with decreases in the solution ionic strength then it saturates. The reduced value of the system osmotic coefficient is a universal function of the ratio of the concentration of osmotically active counterions and salt concentration in salt reservoir. Simulation results are in a very good agreement with osmotic pressure measurements in sodium polystyrene sulfonate, DNA, polyacrylic acid, sodium polyanetholesulfonic acid, polyvinylbenzoic acid, and polydiallyldimethylammonium chloride solutions.

  8. Electrostatic Self-Assembled Multilayers from Side Chain Azo Polyelectrolytes

    Institute of Scientific and Technical Information of China (English)

    庹新林; 陈峥; 邓永红; 王晓工; 刘德山

    2002-01-01

    Photoresponsive behavior and self-assembly properties of three side chain azo polyelectrolytes, poly (2-(4-phenylazophenoxy) ethanol-co-acrylic acid) (PPAPE), poly (2-(4-(4′-nitrophenylazo) phenoxy) ethanol-co-acrylic acid) (PNAPE), and poly (2-(4-(4′-ethoxyphenylazo) phenoxy) ethanol-co-acrylic acid) (PEAPE), were studied. These polyelectrolytes with different degrees of functionalization of azo chromophores were fabricated into nano-composite multilayers using two types of dipping solutions through a layer-by-layer electrostatic self-assembling process. Results show that the ratio between tetrahydrofuran (THF) and H2O significantly influences the photoresponsive behavior of PNAPE in THF-H2O mixture. The THF-H2O dipping solution, used in this work for self-assembly of hydrophobic polyelectrolytes, is proved to be as applicable as aqueous dipping solution for normal self-assembly of hydrophobic polyelectrolytes. However, significant differences in the multilayer growth between the two systems were also observed, which resulted from the remarkable difference of the existing forms of the polyelectrolytes in these two dipping solutions.

  9. Changes of the molecular structure in polyelectrolyte multilayers under stress.

    Science.gov (United States)

    Früh, Johannes; Köhler, Ralf; Möhwald, Helmuth; Krastev, Rumen

    2010-10-01

    Polyelectrolyte multilayers (PEMs) produced by layer-by-layer (LbL) self-assembly find different applications. Often the PEMs are exposed to mechanical stress which they have to sustain. A correlation of the mechanical properties of PEM on macroscopic level with the ordering of polyelectrolyte molecules on molecular level is of interest. Our study is focused on the changes of orientation of the polyelectrolyte molecules when the PEM is under lateral mechanical stress. The PEM was prepared from pyrene (PY) labeled polystyrene sulfonate (PSS-PY) and poly(diallyldimethylammonium) chloride (PDDA) on sheets of polydimethylsiloxane (PDMS) rubber used as substrates. The LbL dipping technique was used for the formation of PEMs. A special stretching device was constructed which allows the fluorescence of the films under stress to be observed. The change in the fluorescence spectra which can be attributed to a PY ordering change from the PEM under stress of up to 10% was monitored. We observed that PEMs undergo a plastic deformation under external mechanical stretching. We conclude that under mechanical stress the polyelectrolyte molecules organized in polyelectrolyte multilayers experience an irreversible transition from the coiled to decoiled state. PMID:20809658

  10. Nuclear magnetic relaxation studies on polyelectrolytes with water

    International Nuclear Information System (INIS)

    Studies on the longitudinal and transverse relaxation times (T1 and T2) of 1H and 23Na in water-polyelectrolytes systems were carried out. The polyelectrolyte samples used were sodium polystyrene sulfonate, sodium lignosulfonate and sodium cellulose sulfate. The water content (Wc's) of the samples was varied from 0 to 2.0 (grams of water per gram of polyelectrolyte). A minimum value for 1HT1 values of water in the system was observed at a temperature ranging from -25 to -40 degree C. The temperature where the 1HT1 minimum value was observed depended on Wc, corresponding to the crystallization of water in each system. From 1HT1 two groups of water molecules (bound and free water) are considered to exist in water-polyelectrolyte systems. The calculated τc values of bound water increased with decreasing temperature from the order of 10-7 sec to 10-6 sec. The observed 23Na in the water-polyelectrolyte systems relaxed with a single T1. 23NaT2 values showed that the relaxation process was separated into two fractions

  11. A Memristor-Based Hyperchaotic Complex Lü System and Its Adaptive Complex Generalized Synchronization

    Directory of Open Access Journals (Sweden)

    Shibing Wang

    2016-02-01

    Full Text Available This paper introduces a new memristor-based hyperchaotic complex Lü system (MHCLS and investigates its adaptive complex generalized synchronization (ACGS. Firstly, the complex system is constructed based on a memristor-based hyperchaotic real Lü system, and its properties are analyzed theoretically. Secondly, its dynamical behaviors, including hyperchaos, chaos, transient phenomena, as well as periodic behaviors, are explored numerically by means of bifurcation diagrams, Lyapunov exponents, phase portraits, and time history diagrams. Thirdly, an adaptive controller and a parameter estimator are proposed to realize complex generalized synchronization and parameter identification of two identical MHCLSs with unknown parameters based on Lyapunov stability theory. Finally, the numerical simulation results of ACGS and its applications to secure communication are presented to verify the feasibility and effectiveness of the proposed method.

  12. Evaluation of shape complexity based on STL data

    Directory of Open Access Journals (Sweden)

    B. Valentan

    2006-04-01

    Full Text Available Purpose: Purpose of this paper is to present a part complexity, based on basic information of the STL data.Design/methodology/approach: This paper presents a few methods of evaluating the complexity of the shape, based on the parts STL data. Methods vary from very simple based on the number of triangles in STL file and the parts volume, to the more complex mathematical determination based on the relations of the basic STL data.Findings: We discovered that evaluation of shape complexity based only on basic data of STL data gives us some basic view on part complexity.Research limitations/implications: For parts with large block volume/part volume ratio and thinner parts with free form surfaces only the first method is suitable and gives suitable results.Practical implications: The complexity of the shape of a part is an important factor for all manufacturing procedures. When using conventional machining, the parts complexity presents a key factor in determining the optimal way of manufacturing. Also, when using rapid tooling (for example silicon rubber moulding the complexity of the part determines the parting plane layout and eventual tool construction (inserts, cores, etc.. Even when using certain rapid prototyping procedures, the support material consumption depends highly on the complexity of the part and together with the problem of optimal orientation and position of the part, significantly influences the manufacturing costs. At the end of the article a few test method are presented that try to determine the complexity regarding to the procedure by which the part will be manufactured.Originality/value: Choosing maximum efficient manufacturing processes on base of part complexity is a new perspective in manufacturing, which, properly evolved and complied can cause revolution in manufacturing optimization, especially in hybrid manufacturing processes.

  13. Polyelectrolyte multilayer films: A sponge for insulin?

    Science.gov (United States)

    Ladhari, Nadia; Hemmerlé, Joseph; Haikel, Youssef; Voegel, Jean-Claude; Ball, Vincent

    2010-01-01

    Considering restrictive diabetes treatments, new insulin administration strategies constitute a huge medical challenge. This study aimed at developing a new support for insulin reservoirs, using polyelectrolyte multilayer films (PEM films), and thus studying this hormone release in a progressive manner. At first, insulin was loaded in (PDADMAC-PAA)n films, by immerging them for various periods of time (2, 14 and 24 h) in a solution containing this protein. Confocal laser scanning microscopy (CLSM) revealed that insulin-FITC could diffuse inside the film with a bigger concentration in the upper part of the film (after 2 and 14 h in contact with the polypeptide solution), and then in the whole film (after 24 h) from a solution at pH=4.3 (below insulin's isolelectric point). Environmental scanning electron microscopy (ESEM) and CLSM showed that the film swells upon insulin loading. We finally investigated the insulin release by ATR-FTIR spectroscopy. It revealed that a loaded (PDADMAC-PAA)15 film, immerged in distilled water, showed no measurable insulin release. In contrast, a slow unloading was observed in the presence of a NaCl 0.15 M solution (salinity close to physiological serum). This study could open the route for a new way of insulin delivery. PMID:20930331

  14. Polyelectrolyte/surfactant films spread from neutral aggregates.

    Science.gov (United States)

    Campbell, Richard A; Tummino, Andrea; Noskov, Boris A; Varga, Imre

    2016-06-28

    We describe a new methodology to prepare loaded polyelectrolyte/surfactant films at the air/water interface by exploiting Marangoni spreading resulting from the dynamic dissociation of hydrophobic neutral aggregates dispensed from an aqueous dispersion. The system studied is mixtures of poly(sodium styrene sulfonate) with dodecyl trimethylammonium bromide. Our approach results in the interfacial confinement of more than one third of the macromolecules in the system even though they are not even surface-active without the surfactant. The interfacial stoichiometry of the films was resolved during measurements of surface pressure isotherms in situ for the first time using a new implementation of neutron reflectometry. The interfacial coverage is determined by the minimum surface area reached when the films are compressed beyond a single complete surface layer. The films exhibit linear ripples on a length scale of hundreds of micrometers during the squeezing out of material, after which they behave as perfectly insoluble membranes with consistent stoichiometric charge binding. We discuss our findings in terms of scope for the preparation of loaded membranes for encapsulation applications and in deposition-based technologies. PMID:27221521

  15. Polyelectrolytes Ability in Reducing Atrazine Concentration in Water: Surface Effects

    Directory of Open Access Journals (Sweden)

    Mohamad Faiz Mohd Amin

    2014-01-01

    Full Text Available This paper reports on the direct ability of two positively charged organic polyelectrolytes (natural-based and synthetic to reduce the atrazine concentration in water. The adsorption study was set up using multiple glass vessels with different polymer dosing levels followed by ultrafiltration with a 1 kDa membrane. The addition of polymers exhibited a capability in reducing the atrazine concentration up to a maximum of 60% in surface-to-volume ratio experiments. In the beginning, the theoretical L-type of the isotherm of Giles’ classification was expected with an increase in the dosage of the polymer. However, in this study, the conventional type of isotherm was not observed. It was found that the adsorption of the cationic polymer on the negatively charged glass surface was necessary and influential for the removal of atrazine. Surface-to-volume ratio adsorption experiments were performed to elucidate the mechanisms and the polymer configuration. The glass surface area was determined to be a limiting parameter in the adsorption mechanism.

  16. A complexity lower bound based on software engineering concepts

    OpenAIRE

    Rojas Paredes, Andrés

    2013-01-01

    We consider the problem of polynomial equation solving also known as quantifier elimination in Effective Algebraic Geometry. The complexity of the first elimination algorithms were double exponential, but a considerable progress was carried out when the polynomials were represented by arithmetic circuits evaluating them. This representation improves the complexity to pseudo–polynomial time. The question is whether the actual asymptotic complexity of circuit– based elimination algorithms ma...

  17. Comprehensive Complexity-Based Failure Modeling for Maintainability and Serviceability

    OpenAIRE

    Meselhy, K. T.; ElMaraghy, H. A.; ElMaraghy, W. H.

    2009-01-01

    Failures are the primary triggers for repair and maintenance actions. A clear definition of failure events is important in order to improve maintainability and serviceability. A comprehensive complexity-based mathematical definition of failure is introduced. The applicability of the developed failure model to different complexity definitions is discussed. A new metric is introduced to capture the change in complexity associated with function degradation. A case study is present...

  18. New software engineering paradigm based on complexity science

    CERN Document Server

    Xiong, Jay

    2011-01-01

    This book describes a complete revolution in software engineering based on complexity science through the establishment of NSE -- Nonlinear Software Engineering paradigm which complies with the essential principles of complexity science, including the Nonlinearity principle, the Holism principle, the Complexity Arises From Simple Rules principle, the Initial Condition Sensitivity principle, the Sensitivity to Change principle, the Dynamics principle, the Openness principle, the Self-organization principle, and the Self-adaptation principle. The aims of this book are to offer revolutionary solu

  19. A novel, biodegradable and reversible polyelectrolyte platform for topical-colonic delivery of pentosan polysulphate.

    Science.gov (United States)

    Shah, Hardik K; Conkie, Jim A; Tait, Robert C; Johnson, James R; Wilson, Clive G

    2011-02-14

    The goal of the present work was to develop a swellable hydrogel colonic delivery system, which would maximise the availability of the therapeutic agent at a site of inflammation, especially where the water is scarce. A novel method was developed to manufacture a biodegradable and reversible polyelectrolyte complex (PEC) containing chitosan and poly acrylic-acid (PAA). The PEC was analysed using FTIR and DSC, which confirmed the formation of non-permanent swollen gel-network at an alkaline pH. Pentosan polysulphate (PPS) was incorporated in a PEC and an activated partial thromboplastin time assay was developed to measure the release of PPS from PEC. In vitro studies suggested that the release of PPS was dependent on the initial drug loading and the composition of the PEC. The gel strength of the swollen network, determined using a texture analyser, was dependent on polymer composition and the amount of PPS incorporated. Bacterial enzymes were collected from the rat caecum and colon for the digestion studies and characterised for glucosidase activity, glucuronidase activity and protein content. The digestion of the reversible polyelectrolyte complexes was measured using a dinitro salicylic acid assay and an increased release of drug was also confirmed in the presence of bacterial enzymes.

  20. A novel, biodegradable and reversible polyelectrolyte platform for topical-colonic delivery of pentosan polysulphate.

    Science.gov (United States)

    Shah, Hardik K; Conkie, Jim A; Tait, Robert C; Johnson, James R; Wilson, Clive G

    2011-02-14

    The goal of the present work was to develop a swellable hydrogel colonic delivery system, which would maximise the availability of the therapeutic agent at a site of inflammation, especially where the water is scarce. A novel method was developed to manufacture a biodegradable and reversible polyelectrolyte complex (PEC) containing chitosan and poly acrylic-acid (PAA). The PEC was analysed using FTIR and DSC, which confirmed the formation of non-permanent swollen gel-network at an alkaline pH. Pentosan polysulphate (PPS) was incorporated in a PEC and an activated partial thromboplastin time assay was developed to measure the release of PPS from PEC. In vitro studies suggested that the release of PPS was dependent on the initial drug loading and the composition of the PEC. The gel strength of the swollen network, determined using a texture analyser, was dependent on polymer composition and the amount of PPS incorporated. Bacterial enzymes were collected from the rat caecum and colon for the digestion studies and characterised for glucosidase activity, glucuronidase activity and protein content. The digestion of the reversible polyelectrolyte complexes was measured using a dinitro salicylic acid assay and an increased release of drug was also confirmed in the presence of bacterial enzymes. PMID:21093555

  1. pH and Salt Effects on the Associative Phase Separation of Oppositely Charged Polyelectrolytes

    Directory of Open Access Journals (Sweden)

    Prateek K. Jha

    2014-05-01

    Full Text Available The classical Voorn-Overbeek thermodynamic theory of complexation and phase separation of oppositely charged polyelectrolytes is generalized to account for the charge accessibility and hydrophobicity of polyions, size of salt ions, and pH variations. Theoretical predictions of the effects of pH and salt concentration are compared with published experimental data and experiments we performed, on systems containing poly(acrylic acid (PAA as the polyacid and poly(N,N-dimethylaminoethyl methacrylate (PDMAEMA or poly(diallyldimethyl ammonium chloride (PDADMAC as the polybase. In general, the critical salt concentration below which the mixture phase separates, increases with degree of ionization and with the hydrophobicity of polyelectrolytes. We find experimentally that as the pH is decreased below 7, and PAA monomers are neutralized, the critical salt concentration increases, while the reverse occurs when pH is raised above 7. We predict this asymmetry theoretically by introducing a large positive Flory parameter (= 0.75 for the interaction of neutral PAA monomers with water. This large positive Flory parameter is supported by molecular dynamics simulations, which show much weaker hydrogen bonding between neutral PAA and water than between charged PAA and water, while neutral and charged PDMAEMA show similar numbers of hydrogen bonds. This increased hydrophobicity of neutral PAA at reduced pH increases the tendency towards phase separation despite the reduction in charge interactions between the polyelectrolytes. Water content and volume of coacervate are found to be a strong function of the pH and salt concentration.

  2. Electrokinetics in polyelectrolyte grafted nanofluidic channels modulated by the ion partitioning effect.

    Science.gov (United States)

    Poddar, Antarip; Maity, Debonil; Bandopadhyay, Aditya; Chakraborty, Suman

    2016-07-01

    The effects of ion partitioning on the electrokinetics in a polyelectrolyte grafted nanochannel, which is the representative of a soft nanochannel, are analyzed. Earlier studies in this regard have considered low polyelectrolyte layer (PEL) grafting density at the rigid nanochannel wall and, hence, an equal permittivity inside and outside the grafted layer. In order to overcome this shortcoming, the concept of Born energy is revisited. The coupled system of the modified Poisson-Boltzmann and Navier-Stokes equation is solved numerically, going beyond the widely employed Debye-Hückel linearization and low PEL densities. The complex interplay between the hydrodynamics and charge distribution, modulated by the ion partitioning effect, along with their consequent effects on the streaming potential and electrokinetic energy conversion efficiency (EKEC) have been systemically investigated. It has been observed that the ion partitioning effect reduces the EKEC in comparison to the case with equal permittivity up to a certain electrical double layer thickness after which it increases the EKEC. For a high concentration of mobile charges within the PEL, the net gain in the maximum EKEC due to the ion partitioning effect is about 10 fold that of the case when the ion partitioning effect is not considered. We delve into the various scaling regimes in the streaming potential and intriguingly point out the exact location of peaks in efficiency. The present study also reveals the possibility of improvement in streaming potential mediated energy conversion by the use of polyelectrolyte materials, which possess substantially lower dielectric permittivity than the bulk electrolyte. PMID:27306568

  3. On the mesoscopic origins of high viscosities in some polyelectrolyte-surfactant mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Ingo, E-mail: ingo.hoffmann@tu-berlin.de [Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin (Germany); Institut Max von Laue-Paul Langevin (ILL), F-38042 Grenoble Cedex 9 (France); Farago, Bela; Schweins, Ralf; Falus, Peter; Sharp, Melissa [Institut Max von Laue-Paul Langevin (ILL), F-38042 Grenoble Cedex 9 (France); Prévost, Sylvain [Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin (Germany); Helmholtz-Zentrum Berlin, D-14109 Berlin (Germany); Gradzielski, Michael, E-mail: michael.gradzielski@tu-berlin.de [Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin (Germany)

    2015-08-21

    the dynamics especially of the polyelectrolyte within the complexes.

  4. On the mesoscopic origins of high viscosities in some polyelectrolyte-surfactant mixtures

    International Nuclear Information System (INIS)

    the dynamics especially of the polyelectrolyte within the complexes

  5. Enhancing synchronization based on complex gradient networks.

    Science.gov (United States)

    Wang, Xingang; Lai, Ying-Cheng; Lai, Choy Heng

    2007-05-01

    The ubiquity of scale-free networks in nature and technological applications and the finding that such networks may be more difficult to synchronize than homogeneous networks pose an interesting phenomenon for study in network science. We argue and demonstrate that, in the presence of some proper gradient fields, scale-free networks can be more synchronizable than homogeneous networks. The gradient structure can in fact arise naturally in any weighted and asymmetrical networks; based on this we propose a coupling scheme that permits effective synchronous dynamics on the network. The synchronization scheme is verified by eigenvalue analysis and by direct numerical simulations using networks of nonidentical chaotic oscillators. PMID:17677146

  6. An entropy based measure for comparing distributions of complexity

    Science.gov (United States)

    Rajaram, R.; Castellani, B.

    2016-07-01

    This paper is part of a series addressing the empirical/statistical distribution of the diversity of complexity within and amongst complex systems. Here, we consider the problem of measuring the diversity of complexity in a system, given its ordered range of complexity types i and their probability of occurrence pi, with the understanding that larger values of i mean a higher degree of complexity. To address this problem, we introduce a new complexity measure called case-based entropyCc - a modification of the Shannon-Wiener entropy measure H. The utility of this measure is that, unlike current complexity measures-which focus on the macroscopic complexity of a single system-Cc can be used to empirically identify and measure the distribution of the diversity of complexity within and across multiple natural and human-made systems, as well as the diversity contribution of complexity of any part of a system, relative to the total range of ordered complexity types.

  7. Radius of gyration and intrinsic viscosity of polyelectrolyte solutions

    Energy Technology Data Exchange (ETDEWEB)

    Milas, M.; Borsali, R.; Rinaudo, M. [CNRS, Cedex (France)

    1993-12-31

    Relatively low molecular weights polyelectrolytes (10{sup 4}-10{sup 6}) behave as worm-like chain when electrostatic repulsions are assumed to govern the excluded volume parameter. Under such conditions, predictions of chain expansion and effect of polyelectrolyte concentrations are made assuming that unperturbed dimensions could be obtained at infinite salt content. Experimental studies of an ionic polysaccharide, namely the Na-hyaluronate, were done and the values obtained for the radius of gyration as well as the intrinsic viscosity at different charge densities are in good agreement with the predictions.

  8. Adsorption of highly charged Gaussian polyelectrolytes onto oppositely charged surfaces

    Science.gov (United States)

    Dutta, Sandipan; Jho, Y. S.

    2016-03-01

    In many biological processes highly charged biopolymers are adsorbed onto oppositely charged surfaces of macroions and membranes. They form strongly correlated structures close to the surface which cannot be explained by the conventional Poisson-Boltzmann theory. In this work strong coupling theory is used to study the adsorption of highly charged Gaussian polyelectrolytes. Two cases of adsorptions are considered, when the Gaussian polyelectrolytes are confined (a) by one charged wall, and (b) between two charged walls. The effects of salt and the geometry of the polymers on their adsorption-depletion transitions in the strong coupling regime are discussed.

  9. Comparative Analysis of EEG Signals Based on Complexity Measure

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The aim of this study is to identify the functions and states of the brains according to the values of the complexity measure of the EEG signals. The EEG signals of 30 normal samples and 30 patient samples are collected. Based on the preprocessing for the raw data, a computational program for complexity measure is compiled and the complexity measures of all samples are calculated. The mean value and standard error of complexity measure of control group is as 0.33 and 0.10, and the normal group is as 0.53 an...

  10. Complexity Measurement of Large-Scale Software System Based on Complex Network

    Directory of Open Access Journals (Sweden)

    Dali Li

    2014-05-01

    Full Text Available With the increase of software system complexity, the traditional measurements can not meet the requirements, for the reason that the developers need control the software quality effectively and guarantee the normal operation of software system. Hence how to measure the complexity of large-scale software system has been a challenge problem. In order to solve this problem, the developers have to obtain a good method to measure the complexity of software system first. Only through this work, the software quality and the software structure could be controlled and optimized. Note that the complex network theory has offered a new theoretical understanding and a new perspective to solve this kind of complexity problem, this work discusses the complexity phenomenon in large-scale software system. Based on this, some complexity measurements of large-scale software system are put forward from static structure and dynamic structure perspectives. Furthermore, we find some potential complexity characteristics in large-scale software networks through the numerical simulations. The proposed measurement methods have a guiding significance on the development for today's large-scale software system. In addition, this paper presents a new technique for the structural complexity measurements of large-scale software system

  11. High-Permittivity Conjugated Polyelectrolyte Interlayers for High-Performance Bulk Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Kesters, Jurgen; Govaerts, Sanne; Pirotte, Geert; Drijkoningen, Jeroen; Chevrier, Michèle; Van den Brande, Niko; Liu, Xianjie; Fahlman, Mats; Van Mele, Bruno; Lutsen, Laurence; Vanderzande, Dirk; Manca, Jean; Clément, Sébastien; Von Hauff, Elizabeth; Maes, Wouter

    2016-03-16

    Conjugated polyelectrolyte (CPE) interfacial layers present a powerful way to boost the I-V characteristics of organic photovoltaics. Nevertheless, clear guidelines with respect to the structure of high-performance interlayers are still lacking. In this work, impedance spectroscopy is applied to probe the dielectric permittivity of a series of polythiophene-based CPEs. The presence of ionic pendant groups grants the formation of a capacitive double layer, boosting the charge extraction and device efficiency. A counteracting effect is the diminishing affinity with the underlying photoactive layer. To balance these two effects, we found copolymer structures containing nonionic side chains to be beneficial. PMID:26927416

  12. Wigner crystal model of counterion induced bundle formation of rod-like polyelectrolytes

    OpenAIRE

    Shklovskii, B. I.

    1998-01-01

    A simple electrostatic theory of condensation of rod-like polyelectrolytes under influence of polyvalent ions is proposed. It is based on the idea that Manning condensation of ions results in formation of the Wigner crystal on a background of a bundle of rods. It is shown that, depending on a single dimensionless parameter, this can be the densely packed three-dimensional Wigner crystal or the two-dimensional crystal on the rod surfaces. For DNA the location of charge on the spiral results in...

  13. Layer-by-layer coating of textile with two oppositely charged cyclodextrin polyelectrolytes for extended drug delivery.

    Science.gov (United States)

    Junthip, Jatupol; Tabary, Nicolas; Chai, Feng; Leclercq, Laurent; Maton, Mickael; Cazaux, Frederic; Neut, Christel; Paccou, Laurent; Guinet, Yannick; Staelens, Jean-Noel; Bria, Marc; Landy, David; Hédoux, Alain; Blanchemain, Nicolas; Martel, Bernard

    2016-06-01

    The coating of a nonwoven textile by polyelectrolyte multilayer film (PEM) issued from cationic and anionic β-cyclodextrin (βCD) polyelectrolytes according to the layer-by-layer (LbL) technique was successfully attempted. The tert-butyl benzoic acid (TBBA) was used as drug model to evaluate the loading capacity and sustained release properties of this PEM system. The build-up of the multilayer assembly was monitored in situ by optical waveguide lightmode spectroscopy (OWLS) on the one hand, and was assessed by gravimetry on the other hand when applied onto the textile substrate. In parallel, the complexation study of TBBA with both CD polyelectrolytes was also investigated by nuclear magnetic resonance (NMR) and isothermal titration calorimetry (ITC). The influence of thermal crosslinking of the multilayered coating on its stability and on TBBA release kinetics in phosphate buffered saline (PBS) at 37°C was studied. Finally, biological and microbiological tests were performed to investigate the cytocompatibility and the intrisic antibacterial activity of multilayer assemblies. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1408-1424, 2016. PMID:26833891

  14. Forming Reversible Gels with Triblock Polyelectrolytes: a Field-theoretic Study

    Science.gov (United States)

    Audus, Debra; Fredrickson, Glenn

    2011-03-01

    Recently, two research groups have formed reversible gels using triblock polyelectrolytes (Lemmers et al. 2010; Hunt et al., in preparation). This gel formation is driven by a phenomenon called complex coacervation, in which two oppositely charged homopolymers in solution phase separate into a polymer rich phase, known as a coacervate, and a solution phase. If instead, the polymers are triblocks with a neutral midblock and charged end blocks, under appropriate conditions they will microphase separate into micelles with cores of coacervated charged groups and coronas of neutral midblocks. These neutral midblocks act as bridges between the micelles, thereby creating a gel. One of the advantages of forming gels in this way is that the coacervate domains, and thus the gel, can be easily tuned by varying parameters such as pH, salt concentration and temperature. In order to understand the microstructures and solution sensitivity of these reversible gels, we have numerically simulated field-theoretic models of triblock polyelectrolyte mixtures in an implicit solvent. Because coacervation is driven by charge correlations, the usual mean-field assumption fails, and it is necessary to study the model beyond the level of SCFT.

  15. Multiscale Modeling of Dendrimers and Their Interactions with Bilayers and Polyelectrolytes

    Directory of Open Access Journals (Sweden)

    Ronald G. Larson

    2009-01-01

    Full Text Available Recent advances in molecular dynamics simulation methodologies and computational power have allowed accurate predictions of dendrimer size, shape, and interactions with bilayers and polyelectrolytes with modest computational effort. Atomistic and coarse-grained (CG models show strong interactions of cationic dendrimers with lipid bilayers. The CG simulations with explicit lipid and water capture bilayer penetration and pore formation, showing that pore formation is enhanced at high dendrimer concentration, but suppressed at low temperature and high salt concentration, in agreement with experiments. Cationic linear polymers have also been simulated, but do not perforate membranes, evidently because by deforming into a pancake, the charges on a linear polymer achieve intimate contact with a single bilayer leaflet. The relatively rigid dendrimers, on the other hand, penetrate the bilayer, because only by interacting with both leaflets can they achieve a similar degree of contact between charged groups. Also, a “dendrimer-filled vesicle” structure for the dendrimer-membrane interaction is predicted by mesoscale thermodynamic simulations, in agreement with a picture derived from experimental observations. In simulations of complexes of dendrimer and polyelectrolyte, anionic linear chains wrap around the cationic dendrimer and penetrate inside it. Overall, these new results indicate that simulations can now provide predictions in excellent agreement with experimental observations, and provide atomic-scale insights into dendrimer structure and dynamics.

  16. Microstructure and Phase Behavior of Cationic Gemini/Anionic Polyelectrolyte/Water Ternary System

    Institute of Scientific and Technical Information of China (English)

    皮瑛瑛; 尚亚卓; 彭昌军; 刘洪来

    2006-01-01

    The microstructure of cationic gemini surfactant 1,6-bis(dodecyldimethylammonium) hexane dibromide [C12H25(CH3)2N-(CH2)6-N(CH3)2C12H25·2Br] (12-6-12·2Br-) and oppositely charged polyelectrolyte poly(acrylic acid,sodium salt) (NaPA) in aqueous solution has been studied by using fluorescence, conductivity measurement, freeze-etching and TEM. The data obtained from fluorescence and conductivity measurement show that micelle-like or complex can form between the gemini surfactant (12-6-12.2Br-) and polyelectrolyte NaPA due to the static electric interaction and hydrophobic forces. Through freeze-etching and TEM, the microstructure of the mixture solution has been studied, which is consistent with the result from micropolarity. Comparing the fluorescence spectrum of system of dodecyltrimethylammonium bromide (DTAB) and NaPA with that of system of gemini surfactant (12-6-12.2Br-) and NaPA, it can be found that the interaction of (12-6-12.2Br-) and NaPA in aqueous solution has also been detected. It can be shown that the precipitate will transform into gel in higher NaPA concentration.

  17. Formation of surface-attached microstructured polyelectrolyte brushes

    Institute of Scientific and Technical Information of China (English)

    Hai Ning Zhang

    2008-01-01

    Surface-attached micropatterned polyelectrolyte brushes on planar solid surfaces are generated using free radical polymerization photo-initiated by self-assembled initiator monolayers. It is shown that the formed patterns can be either negative or positive with different patterning processes.

  18. Polyelectrolyte microcapsules for sustained delivery of water-soluble drugs

    International Nuclear Information System (INIS)

    Polyelectrolyte capsules composed of weak polyelectrolytes are introduced as a simple and efficient system for spontaneous encapsulation of low molecular weight water-soluble drugs. Polyelectrolyte capsules were prepared by layer-by-layer (LbL) assembling of weak polyelectrolytes, poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMA) on polystyrene sulfonate (PSS) doped CaCO3 particles followed by core removal with ethylene-diaminetetraacetic acid (EDTA). The loading process was observed by confocal laser scanning microscopy (CLSM) using tetramethylrhodamineisothiocyanate labeled dextran (TRITC-dextran) as a fluorescent probe. The intensity of fluorescent probe inside the capsule decreased with increase in cross-linking time. Ciprofloxacin hydrochloride (a model water-soluble drug) was spontaneously deposited into PAH/PMA capsules and their morphological changes were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The quantitative study of drug loading was also elucidated which showed that drug loading increased with initial drug concentration, but decreased with increase in pH. The loaded drug was released in a sustained manner for 6 h, which could be further extended by cross-linking the capsule wall. The released drug showed significant antibacterial activity against E. coli. These findings indicate that such capsules can be potential carriers for water-soluble drugs in sustained/controlled drug delivery applications.

  19. Humidity Sensitive Properties of a Silicone-containing Polyelectrolyte Material

    Institute of Scientific and Technical Information of China (English)

    Mu Jie YANG; Zong Wu YAO; You Si CHEN; Yang LI

    2006-01-01

    Resistive-type film humidity sensors were prepared with a silicone-containing polyelectrolyte (Si-PE) and their humidity sensitive properties have been investigated. The sensors so obtained show high sensitivity to humidity variation over a wide range of RH (20-96%).In addition, they exhibit high reversibility, quick response and well long-term stability.

  20. Polyelectrolyte microcapsules for sustained delivery of water-soluble drugs

    Energy Technology Data Exchange (ETDEWEB)

    Anandhakumar, S.; Debapriya, M. [Department of Materials Engineering, Indian Institute of Science, Bangalore, 560012 (India); Nagaraja, V. [Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012 (India); Raichur, Ashok M., E-mail: amr@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science, Bangalore, 560012 (India)

    2011-03-12

    Polyelectrolyte capsules composed of weak polyelectrolytes are introduced as a simple and efficient system for spontaneous encapsulation of low molecular weight water-soluble drugs. Polyelectrolyte capsules were prepared by layer-by-layer (LbL) assembling of weak polyelectrolytes, poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMA) on polystyrene sulfonate (PSS) doped CaCO{sub 3} particles followed by core removal with ethylene-diaminetetraacetic acid (EDTA). The loading process was observed by confocal laser scanning microscopy (CLSM) using tetramethylrhodamineisothiocyanate labeled dextran (TRITC-dextran) as a fluorescent probe. The intensity of fluorescent probe inside the capsule decreased with increase in cross-linking time. Ciprofloxacin hydrochloride (a model water-soluble drug) was spontaneously deposited into PAH/PMA capsules and their morphological changes were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The quantitative study of drug loading was also elucidated which showed that drug loading increased with initial drug concentration, but decreased with increase in pH. The loaded drug was released in a sustained manner for 6 h, which could be further extended by cross-linking the capsule wall. The released drug showed significant antibacterial activity against E. coli. These findings indicate that such capsules can be potential carriers for water-soluble drugs in sustained/controlled drug delivery applications.

  1. Iterative Soft Decision Based Complex K-best MIMO Decoder

    Directory of Open Access Journals (Sweden)

    Mehnaz Rahman

    2015-11-01

    Full Text Available This paper presents an iterative soft decision based complex multiple input multiple output (MIMO decoding algorithm, which reduces the complexity of Maximum Likelihood (ML detector. We develop a novel iterative complex K-best decoder exploiting the techniques of lattice reduction for 8×8 MIMO. Besides list size, a new adjustable variable has been introduced in order to control the on-demand child expansion. Following this method, we obtain 6.9 to 8.0 dB improvement over real domain K-best decoder and 1.4 to 2.5 dB better performance compared to iterative conventional complex decoder for 4th iteration and 64-QAM modulation scheme. We also demonstrate the significance of new parameter on bit error rate. The proposed decoder not only increases the performance, but also reduces the computational complexity to a certain level.

  2. Metal-Organic-Framework-Templated Polyelectrolyte Nanocapsules for the Encapsulation and Delivery of Small-Molecule-Polymer Conjugates.

    Science.gov (United States)

    Liu, Shuo; Chen, Jianbin; Bao, Xiaojia; Li, Tao; Ling, Yunyang; Li, Chunxiang; Wu, Chuanliu; Zhao, Yibing

    2016-06-21

    Herein, we report a strategy for exploiting nanoscale metal-organic frameworks (nano-MOFs) as templates for the layer-by-layer (LbL) assembly of polyelectrolytes. Because small-molecule drugs or imaging agents cannot be efficiently encapsulated by polyelectrolyte nanocapsules, we investigated two promising and biocompatible polymers (comb-shaped polyethylene glycol (PEG) and hyperbranched polyglycerol-based PEG) for the conjugation of model drugs and imaging agents, which were then encapsulated inside the nano-MOF-templated nanocapsules. Furthermore, we also systemically explored the release kinetics of the encapsulated conjugates, and examined how the encapsulation and/or release processes could be controlled by varying the composition and architecture of the polymers. We envision that our nano-MOFs-templated nanocapsules, through combining with small-molecule-polymer conjugates, will represent a new type of delivery system that could open up new opportunities for biomedical applications. PMID:27123998

  3. A fluorescence-Raman dual-imaging platform based on complexes of conjugated polymers and carbon nanotubes.

    Science.gov (United States)

    Liu, Yun; Huang, Jun; Sun, Min-Jie; Yu, Ji-Cheng; Chen, Yu-Lei; Zhang, Yu-Qi; Jiang, Shao-Jun; Shen, Qun-Dong

    2014-01-01

    The present study describes a flexible nanoplatform based on electrostatic assembly of conjugated polyelectrolytes (CPEs) and carboxylated multi-walled carbon nanotubes (cMWNTs). It is demonstrated that the obtained nanocomposites inherit intrinsic optical properties of CPEs and characteristic Raman vibration modes of MWNTs, providing a fluorescence-Raman dual-imaging method for intracellular tracking and locating of MWNTs. We suggest that the cellular internalization of the CPE-cMWNT nanocomposites is a surface charge-dependent process. The strengths of this nanoplatform include satisfying biocompatibility, enhanced protein-repellent property, and ease of implementation, making it available for both in vitro and in vivo applications.

  4. Towards a Complexity Theory of Randomized Search Heuristics: Ranking-Based Black-Box Complexity

    CERN Document Server

    Doerr, Benjamin

    2011-01-01

    Randomized search heuristics are a broadly used class of general-purpose algorithms. Analyzing them via classical methods of theoretical computer science is a growing field. A big step forward would be a useful complexity theory for such algorithms. We enrich the two existing black-box complexity notions due to Wegener and other authors by the restrictions that not actual objective values, but only the relative quality of the previously evaluated solutions may be taken into account by the algorithm. Many randomized search heuristics belong to this class of algorithms. We show that the new ranking-based model gives more realistic complexity estimates for some problems, while for others the low complexities of the previous models still hold.

  5. Safety control program for complex system based on behavior science

    Institute of Scientific and Technical Information of China (English)

    LIANG Mei-jian; YANG Guang; CHEN Da-wei

    2008-01-01

    To control complex system's safety effectively, safety control program was supported based on the principles of behavioral science that shapes organizational be-havior, and organizational behavior produced individual behavior. The program can be structured into a model that consists of three modules including individual behavior rectifi-cation, organization behavior diagnosis and model of safety culture. The research result not only reveals the deep cause of complex system accidents but also provides structural descriptions with the accidents cause.

  6. Safety control program for complex system based on behavior science

    Institute of Scientific and Technical Information of China (English)

    LIANG Mei-jian; YANG Guang; CHEN Da-wei

    2008-01-01

    To control complex system's safety effectively,safety control program was supported based on the principles of behavioral science that shapes organizational behavior,and organizational behavior produced individual behavior.The program can be structured into a model that consists of three modules including individual behavior rectification,organization behavior diagnosis and model of safety culture.The research result not only reveals the deep cause of complex system accidents but also provides structural descriptions with the accidents cause.

  7. EPR spectra of four gadolinium complexes with Schiff bases

    Institute of Scientific and Technical Information of China (English)

    姚克敏; 陈德余; 封子先; 李冬成; 冯亚菲; 何玲

    1995-01-01

    EPR spectra of four new gadolinium complexes with Schiff bases in polycrystalline powder and those of these complexes in three organic solvents were investigated at different temperatures. It has been observed for the first time that their freezing solution spectra are quite different from each other. In THF one peak was observed only, but there were three peaks and typical "U" spectral features appearing in DMF and DMSO at low temperatures. On the basis of spin Hamiltonian of S = 7/2 system, the correlations between crystal field strength in complexes and local symmetry around Gd3+ ions are discussed.

  8. Synthesis, characterization and antimicrobial studies of Schiff base complexes

    Science.gov (United States)

    Zafar, Hina; Ahmad, Anis; Khan, Asad U.; Khan, Tahir Ali

    2015-10-01

    The Schiff base complexes, MLCl2 [M = Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by the template reaction of respective metal ions with 2-acetylpyrrole and 1,3-diaminopropane in 1:2:1 M ratio. The complexes have been characterized by elemental analyses, ESI - mass, NMR (1H and 13C), IR, XRD, electronic and EPR spectral studies, magnetic susceptibility and molar conductance measurements. These studies show that all the complexes have octahedral arrangement around the metal ions. The molar conductance measurements of all the complexes in DMSO indicate their non-electrolytic nature. The complexes were screened for their antibacterial activity in vitro against Gram-positive (Streptococcus pyogenes) and Gram-negative (Klebsiella pneumoniae) bacteria. Among the metal complexes studied the copper complex [CuLCl2], showed highest antibacterial activity nearly equal to standard drug ciprofloxacin. Other complexes also showed considerable antibacterial activity. The relative order of activity against S. Pyogenes is as Cu(II) > Zn(II) > Co(II) = Fe(II) > Ni(II) and with K. Pneumonia is as Cu(II) > Co(II) > Zn(II) > Fe(II) > Ni(II).

  9. Pathway-based Analysis Tools for Complex Diseases: A Review

    Directory of Open Access Journals (Sweden)

    Lv Jin

    2014-10-01

    Full Text Available Genetic studies are traditionally based on single-gene analysis. The use of these analyses can pose tremendous challenges for elucidating complicated genetic interplays involved in complex human diseases. Modern pathway-based analysis provides a technique, which allows a comprehensive understanding of the molecular mechanisms underlying complex diseases. Extensive studies utilizing the methods and applications for pathway-based analysis have significantly advanced our capacity to explore large-scale omics data, which has rapidly accumulated in biomedical fields. This article is a comprehensive review of the pathway-based analysis methods—the powerful methods with the potential to uncover the biological depths of the complex diseases. The general concepts and procedures for the pathway-based analysis methods are introduced and then, a comprehensive review of the major approaches for this analysis is presented. In addition, a list of available pathway-based analysis software and databases is provided. Finally, future directions and challenges for the methodological development and applications of pathway-based analysis techniques are discussed. This review will provide a useful guide to dissect complex diseases.

  10. Recent advances in agent-based complex automated negotiation

    CERN Document Server

    Ito, Takayuki; Zhang, Minjie; Fujita, Katsuhide; Robu, Valentin

    2016-01-01

    This book covers recent advances in Complex Automated Negotiations as a widely studied emerging area in the field of Autonomous Agents and Multi-Agent Systems. The book includes selected revised and extended papers from the 7th International Workshop on Agent-Based Complex Automated Negotiation (ACAN2014), which was held in Paris, France, in May 2014. The book also includes brief introductions about Agent-based Complex Automated Negotiation which are based on tutorials provided in the workshop, and brief summaries and descriptions about the ANAC'14 (Automated Negotiating Agents Competition) competition, where authors of selected finalist agents explain the strategies and the ideas used by them. The book is targeted to academic and industrial researchers in various communities of autonomous agents and multi-agent systems, such as agreement technology, mechanism design, electronic commerce, related areas, as well as graduate, undergraduate, and PhD students working in those areas or having interest in them.

  11. Local algorithm for computing complex travel time based on the complex eikonal equation.

    Science.gov (United States)

    Huang, Xingguo; Sun, Jianguo; Sun, Zhangqing

    2016-04-01

    The traditional algorithm for computing the complex travel time, e.g., dynamic ray tracing method, is based on the paraxial ray approximation, which exploits the second-order Taylor expansion. Consequently, the computed results are strongly dependent on the width of the ray tube and, in regions with dramatic velocity variations, it is difficult for the method to account for the velocity variations. When solving the complex eikonal equation, the paraxial ray approximation can be avoided and no second-order Taylor expansion is required. However, this process is time consuming. In this case, we may replace the global computation of the whole model with local computation by taking both sides of the ray as curved boundaries of the evanescent wave. For a given ray, the imaginary part of the complex travel time should be zero on the central ray. To satisfy this condition, the central ray should be taken as a curved boundary. We propose a nonuniform grid-based finite difference scheme to solve the curved boundary problem. In addition, we apply the limited-memory Broyden-Fletcher-Goldfarb-Shanno technology for obtaining the imaginary slowness used to compute the complex travel time. The numerical experiments show that the proposed method is accurate. We examine the effectiveness of the algorithm for the complex travel time by comparing the results with those from the dynamic ray tracing method and the Gauss-Newton Conjugate Gradient fast marching method.

  12. Local algorithm for computing complex travel time based on the complex eikonal equation.

    Science.gov (United States)

    Huang, Xingguo; Sun, Jianguo; Sun, Zhangqing

    2016-04-01

    The traditional algorithm for computing the complex travel time, e.g., dynamic ray tracing method, is based on the paraxial ray approximation, which exploits the second-order Taylor expansion. Consequently, the computed results are strongly dependent on the width of the ray tube and, in regions with dramatic velocity variations, it is difficult for the method to account for the velocity variations. When solving the complex eikonal equation, the paraxial ray approximation can be avoided and no second-order Taylor expansion is required. However, this process is time consuming. In this case, we may replace the global computation of the whole model with local computation by taking both sides of the ray as curved boundaries of the evanescent wave. For a given ray, the imaginary part of the complex travel time should be zero on the central ray. To satisfy this condition, the central ray should be taken as a curved boundary. We propose a nonuniform grid-based finite difference scheme to solve the curved boundary problem. In addition, we apply the limited-memory Broyden-Fletcher-Goldfarb-Shanno technology for obtaining the imaginary slowness used to compute the complex travel time. The numerical experiments show that the proposed method is accurate. We examine the effectiveness of the algorithm for the complex travel time by comparing the results with those from the dynamic ray tracing method and the Gauss-Newton Conjugate Gradient fast marching method. PMID:27176428

  13. Local algorithm for computing complex travel time based on the complex eikonal equation

    Science.gov (United States)

    Huang, Xingguo; Sun, Jianguo; Sun, Zhangqing

    2016-04-01

    The traditional algorithm for computing the complex travel time, e.g., dynamic ray tracing method, is based on the paraxial ray approximation, which exploits the second-order Taylor expansion. Consequently, the computed results are strongly dependent on the width of the ray tube and, in regions with dramatic velocity variations, it is difficult for the method to account for the velocity variations. When solving the complex eikonal equation, the paraxial ray approximation can be avoided and no second-order Taylor expansion is required. However, this process is time consuming. In this case, we may replace the global computation of the whole model with local computation by taking both sides of the ray as curved boundaries of the evanescent wave. For a given ray, the imaginary part of the complex travel time should be zero on the central ray. To satisfy this condition, the central ray should be taken as a curved boundary. We propose a nonuniform grid-based finite difference scheme to solve the curved boundary problem. In addition, we apply the limited-memory Broyden-Fletcher-Goldfarb-Shanno technology for obtaining the imaginary slowness used to compute the complex travel time. The numerical experiments show that the proposed method is accurate. We examine the effectiveness of the algorithm for the complex travel time by comparing the results with those from the dynamic ray tracing method and the Gauss-Newton Conjugate Gradient fast marching method.

  14. Polyelectrolytes Multilayers to Modulate Cell Adhesion: A Study of the Influence of Film Composition and Polyelectrolyte Interdigitation on the Adhesion of the A549 Cell Line.

    Science.gov (United States)

    Muzzio, Nicolás E; Pasquale, Miguel A; Gregurec, Danijela; Diamanti, Eleftheria; Kosutic, Marija; Azzaroni, Omar; Moya, Sergio E

    2016-04-01

    Polyelectrolyte multilayers (PEMs) with different polycation/polyanion pairs are fabricated by the layer-by-layer technique employing synthetic, natural, and both types of polyelectrolytes. The impact of the chemical composition of PEMs on cell adhesion is assessed by studying cell shape, spreading area, focal contacts, and cell proliferation for the A549 cell line. Cells exhibit good adhesion on PEMs containing natural polycations and poly(sodium 4-styrenesulfonate) (PSS) as polyanion, but limited adhesion is observed on PEMs fabricated from both natural polyelectrolytes. PEMs are then assembled, depositing a block of natural polyelectrolytes on top of a stiffer block with PSS as polyanion. Cell adhesion is enhanced on top of the diblock PEMs compared to purely natural PEMs. This fact could be explained by the interdigitation between polyelectrolytes from the two blocks. Diblock PEM assembly provides a simple means to tune cell adhesion on biocompatible PEMs. PMID:26663657

  15. Build-up of an antimicrobial multilayer coating on a textile support based on a methylene blue–poly(cyclodextrin) complex

    International Nuclear Information System (INIS)

    The aim of this work was to develop an antibacterial multilayer coating activated with methylene blue (MB) and based on chitosan (CHT) and cyclodextrin polyelectrolyte (polyCD) onto a non-woven polyethylene terephthalate (PET) textile support. The MB-free and MB-loaded systems were built-up by applying the dip-coating technique, alternating soak cycles of the PET textile preliminarily modified with carboxylate groups in CHT and in polyCD or polyCD/MB complex solutions. The layer-by-layer assembly build-up was followed by optical waveguide lightmode spectroscopy on the one hand and by gravimetry once it was applied on the textile substrate on the other hand. Two chitosan grades were used, low molecular weight (CHT-L) and medium molecular weight (CHT-M). The influence of the molar ratio CD/MB in the polyCD solutions was varied and finally the system underwent a post reticulation with genipin. Such parameters influences were investigated with regard to the loading capacity in MB of the systems, the release kinetics profiles of MB in pure water, phosphate buffer and MEM media, and the degradation of the self-assembled coating in the same media. Finally, biological and microbiological tests were performed to demonstrate the cytocompatibility of the systems and their ability to display a sustained antibacterial effect of the device through the MB prolonged release. (paper)

  16. An MAS-Based ETL Approach for Complex Data

    CERN Document Server

    Boussaïd, Omar; Darmont, Jérôme

    2008-01-01

    In a data warehousing process, the phase of data integration is crucial. Many methods for data integration have been published in the literature. However, with the development of the Internet, the availability of various types of data (images, texts, sounds, videos, databases...) has increased, and structuring such data is a difficult task. We name these data, which may be structured or unstructured, "complex data". In this paper, we propose a new approach for complex data integration, based on a Multi-Agent System (MAS), in association to a data warehousing approach. Our objective is to take advantage of the MAS to perform the integration phase for complex data. We indeed consider the different tasks of the data integration process as services offered by agents. To validate this approach, we have actually developed an MAS for complex data integration.

  17. Monte Carlo simulation and equation of state for flexible charged hard-sphere chain fluids: Polyampholyte and polyelectrolyte solutions

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Hao; Adidharma, Hertanto, E-mail: adidharm@uwyo.edu [Soft Materials Laboratory, Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie, Wyoming 82071-3295 (United States)

    2014-11-07

    The thermodynamic modeling of flexible charged hard-sphere chains representing polyampholyte or polyelectrolyte molecules in solution is considered. The excess Helmholtz energy and osmotic coefficients of solutions containing short polyampholyte and the osmotic coefficients of solutions containing short polyelectrolytes are determined by performing canonical and isobaric-isothermal Monte Carlo simulations. A new equation of state based on the thermodynamic perturbation theory is also proposed for flexible charged hard-sphere chains. For the modeling of such chains, the use of solely the structure information of monomer fluid for calculating the chain contribution is found to be insufficient and more detailed structure information must therefore be considered. Two approaches, i.e., the dimer and dimer-monomer approaches, are explored to obtain the contribution of the chain formation to the Helmholtz energy. By comparing with the simulation results, the equation of state with either the dimer or dimer-monomer approach accurately predicts the excess Helmholtz energy and osmotic coefficients of polyampholyte and polyelectrolyte solutions except at very low density. It also well captures the effect of temperature on the thermodynamic properties of these solutions.

  18. Structure formation of soil dispersions in the presence of polyelectrolytes on the basis of allyl alcohol and acryl acid derivatives

    Directory of Open Access Journals (Sweden)

    Amankait Asanov

    2015-09-01

    Full Text Available Some changes of structural composition and surface properties of soil dispersions in the presence of polyelectrolytes, based on allyl alcohol and acryl acid derivatives, have been studied. The results show, that the changes in the structure of soil dispersions composition are connected with the added concentration and pH value, that depend on mole ratio and nature of functional groups, as well as on the nature of counterions and concomitant electrolytes, changing with the conditions of polymer analogous conversion and neutralization reaction. Experimental data show, that the change in the conformational state and the length of the macromolecule has a significant impact on the structure-forming effect and the amount of polyelectrolyte, needed to achieve the same degree of structure-forming effect of soil dispersions. The causes for the revealed reasons are shown on the basis of the results of the experiment. Along with this, it was found that particular changes of structural composition and surface properties of the soil dispersions depend on the type and concentration of the added polyelectrolyte.

  19. An electrochemical aptasensor for chiral peptide detection using layer-by-layer assembly of polyelectrolyte-methylene blue/polyelectrolyte-graphene multilayer

    Energy Technology Data Exchange (ETDEWEB)

    Qin Haixia; Liu Jiyang; Chen Chaogui [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Wang Jiahi, E-mail: jhwang@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Wang Erkang, E-mail: ekwang@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer An electrochemical aptasensor for selective detection of peptide is constructed. Black-Right-Pointing-Pointer This aptasensor is based on grapheme multilayer via layer-by-layer assembly. Black-Right-Pointing-Pointer Such multilayer facilitates electron transfer and provides more adsorption sites. - Abstract: Here we demonstrate for the first time that by physically adsorbing aptamer onto conductive film assembled via alternate adsorption of graphene/polyelectrolyte and methylene blue/polyelectrolyte, a label-free electrochemical aptasensor with high sensitivity and selectivity for peptide detection is constructed. Graphene multilayer derived from layer-by-layer assembly has played significant roles in this sensing strategy: allowing accumulation of methylene blue, facilitating electron transfer and providing much more adsorption site. As compared to previous electrochemical aptasensors, the current sensor based on graphene multilayer alternated with electroactive molecule layer offers extremely high capability for sensitive detection of target without interference of environmental surrounding. This electroactive probe-confined graphene multilayer confers great flexibility to combine with differential pulse voltammetry (DPV) together. In the presence of target D entiomer of arginine vasopressin (D-VP), the binding of peptide to aptamer block the electron transfer process of MB, leading to decreased current peak of DPV. By this way, this electrochemical aptasensor based on electroactive molecule-intercalated graphene multilayer provide highly sensitive and specific detection of D-VP with the lowest detectable concentration of 1 ng mL{sup -1} and a wide detection range from 1 to 265 ng mL{sup -1}.

  20. Self-assembled systems of water soluble metal 8-hydroxyquinolates with surfactants and conjugated polyelectrolytes.

    Science.gov (United States)

    Burrows, Hugh D; Costa, Telma; Ramos, M Luisa; Valente, Artur J M; Stewart, Beverly; Justino, Licinia L G; Almeida, Aline I A; Catarina, Nathanny Lessa; Mallavia, Ricardo; Knaapila, Matti

    2016-06-22

    We have studied the interaction of 8-hydroxyquinoline-5-sulfonate (8-HQS) with the metal ions Al(iii) and Zn(ii) in aqueous solution in the presence of tetraalkylammonium surfactants using UV/vis absorption, fluorescence, NMR spectroscopy and electrical conductivity measurements, complemented by DFT calculations and molecular dynamics (MD) simulations. Under appropriate conditions, complexes between 8-HQS and metal ions form rapidly, and have similar electronic, spectroscopic and photophysical properties to the corresponding metal quinolates, such as Alq3. These interact with the cationic surfactants, leading to marked increases in fluorescence intensity. However, significant differences are seen in the behavior of the two metal ions. With aluminium, a stable [Al(8-QS)3](3-) anion is formed, and interacts, predominantly through electrostatic interactions, with the surfactant, without disrupting the metal ion coordination sphere. In contrast, with Zn(ii), there is a competition between the metal ion and surfactants in the interaction with 8-HQS, although the [Zn(8-QS)2(H2O)2](2-) species is stable at appropriate pH and surfactant concentration. The studies are extended to systems with the conjugated polyelectrolyte (CPE) poly-(9,9-bis(6-N,N,N-trimethylammonium)hexyl)-fluorene-phenylene bromide (HTMA-PFP), which has a similar alkylammonium chain to the surfactants. Mixing metal salt, 8-HQS and HTMA-PFP in the presence of a nonionic surfactant leads to the formation of a metal complex/CPE supramolecular assembly between the conjugated polyelectrolyte and the metal/8-HQS complex, as demonstrated by electronic energy transfer. The potential of these systems in sensing, light harvesting, and electron injection/transport layers in organic semiconductor devices is discussed. PMID:26817700

  1. Novel insights in agent-based complex automated negotiation

    CERN Document Server

    Lopez-Carmona, Miguel; Ito, Takayuki; Zhang, Minjie; Bai, Quan; Fujita, Katsuhide

    2014-01-01

    This book focuses on all aspects of complex automated negotiations, which are studied in the field of autonomous agents and multi-agent systems. This book consists of two parts. I: Agent-Based Complex Automated Negotiations, and II: Automated Negotiation Agents Competition. The chapters in Part I are extended versions of papers presented at the 2012 international workshop on Agent-Based Complex Automated Negotiation (ACAN), after peer reviews by three Program Committee members. Part II examines in detail ANAC 2012 (The Third Automated Negotiating Agents Competition), in which automated agents that have different negotiation strategies and are implemented by different developers are automatically negotiated in the several negotiation domains. ANAC is an international competition in which automated negotiation strategies, submitted by a number of universities and research institutes across the world, are evaluated in tournament style. The purpose of the competition is to steer the research in the area of bilate...

  2. Disaster Rescue Simulation based on Complex Adaptive Theory

    Directory of Open Access Journals (Sweden)

    Feng Jiang

    2013-05-01

    Full Text Available Disaster rescue is one of the key measures of disaster reduction. The rescue process is a complex process with the characteristics of large scale, complicate structure, non-linear. It is hard to describe and analyze them with traditional methods. Based on complex adaptive theory, this paper analyzes the complex adaptation of the rescue process from seven features: aggregation, nonlinearity, mobility, diversity, tagging, internal model and building block. With the support of Repast platform, an agent-based model including rescue agents and victim agents was proposed. Moreover, two simulations with different parameters are employed to examine the feasibility of the model. As a result, the proposed model has been shown that it is efficient in dealing with the disaster rescue simulation and can provide the reference for making decisions.

  3. Synthesis of Chiral Metal Complexes of Unsymmetrical Schiff Bases

    Institute of Scientific and Technical Information of China (English)

    SONG; Bo

    2001-01-01

    Recently, in asymmetric catalyst research the great developments of chiral Salen complexes have been made, but the report on unsymmetrical schiff bases is deficient. The unsymmetrical schiff bases complexes are an effective system in catalytically selective Olefin-epoxidations1. At the same time, unsymmetrical schiff bases was immobilized onto polymer supports for heterogenization2. The potential benefits of the catalyst include facilitation of catalyst separation from reagents, simplification of methods for catalyst recycle, and the possible adaptation of the immobilized catalyst to continuous-flow processes. A series of new unsymmetrical schiff bases was synthesized to study the relations between unsymmetry and enantioselectivity and select better catalyst. The following is the route:  ……

  4. The solvation and ion condensation properties for sulfonated polyelectrolytes in different solvents : a computational study

    OpenAIRE

    Smiatek, Jens; Wohlfarth, Andreas; Holm, Christian

    2014-01-01

    In contrast to the broad knowledge about aqueous polyelectrolyte solutions, less is known about the properties in aprotic and apolar solvents. We therefore investigate the behavior of sulfonated polyelectrolytes in sodium form in the presence of different solvents via all-atom molecular dynamics simulations. The results clearly reveal strong variations in ion condensation constants and polyelectrolyte conformations for different solvents like water, dimethyl sulfoxide (DMSO) and chloroform. T...

  5. Fluctuations and interactions of semi-flexible polyelectrolytes in columnar assemblies

    OpenAIRE

    Lee, D.J.; Leikin, S; Wynveen, A.

    2010-01-01

    We have developed a statistical theory for columnar aggregates of semi-flexible polyelectrolytes. The applicability of previous, simplified theories was limited to polyelectrolytes with unrealistically high effective charge and, hence, with strongly suppressed thermal undulations. To avoid this problem, we utilized more consistent approximations for short-range image-charge forces and steric confinement, resulting in new predictions for polyelectrolytes with more practically important, lower ...

  6. The effect of polyelectrolytes and their mixtures on flocculation of kaolin suspensions

    OpenAIRE

    R. Taubayeva; Zh. Lakhbayeva; G. Balykbayeva

    2014-01-01

    The effect of the concentration and charge of the water-soluble polyelectrolytes on the kinetics of aggregation of kaolin particles was studied. It has been shown that the rate of stirring affects formation, size and strength of flocs. The rate of aggregation and the size of the mineral particle forming floccules increase with the increase of reagent concentration and the charge density of the polyelectrolyte. At low concentrations (2.75-3.8 mg/g) of individual polyelectrolytes (FO 4800 SSH, ...

  7. A SHARC based ROB Complex : design and measurement results

    CERN Document Server

    Boterenbrood, H; Kieft, G; Scholte, R; Slopsema, R; Vermeulen, J C

    2000-01-01

    ROB hardware, based on and exploiting the properties of the SHARC DSP and of FPGAs, and the associated software are described. Results from performance measurements and an analysis of the results for a single ROBIn as well as for a ROB Complex with up to 4 ROBIns are presented.

  8. Model-based safety architecture framework for complex systems

    NARCIS (Netherlands)

    Schuitemaker, K.; Rajabalinejad, M.; Braakhuis, J.G.; Podofilini, Luca; Sudret, Bruno; Stojadinovic, Bozidar; Zio, Enrico; Kröger, Wolfgang

    2015-01-01

    The shift to transparency and rising need of the general public for safety, together with the increasing complexity and interdisciplinarity of modern safety-critical Systems of Systems (SoS) have resulted in a Model-Based Safety Architecture Framework (MBSAF) for capturing and sharing architectural

  9. Polyelectrolyte coated multilayered liposomes (nanocapsules) for the treatment of Helicobacter pylori infection.

    Science.gov (United States)

    Jain, Parul; Jain, Sanyog; Prasad, K N; Jain, S K; Vyas, Suresh P

    2009-01-01

    Helicobacter pylori infection is one of the major causes of gastric cancers. A number of systems have already been reported, but 100% eradication has never been achieved. The present invention designs a gastro-retentive drug delivery system incorporated with amoxicillin and metronidazole, specifically suited for the eradication of Helicobacter pylori infections due to its mucoadhesiveness in the presence of polyelectrolyte polymers. The system possesses the advantages of both vesicular and particulate carriers, and it was prepared by alternative coating of polyanion (poly(acrylic acid), PAA) and polycation (poly(allylamine hydrochloride), PAH) using liposomes as the core. Compared with the conventional liposomes, the polyelectrolyte based multilayered system (nanocapsules) gave prolonged drug release in simulated gastric fluid, which is well suited for drug delivery against H. pylori infection in the stomach. In vitro growth inhibition study, agglutination assay, and in situ adherence assay in cultured H. pylori suggested the successful in vitro activity and binding propensity of the system. In vivo bacterial clearance study carried out in a H. pylori infected mouse model finally confirmed the success of the developed novel nanocapsule system. Thus, the newly developed composite nanocapsules along with the use of combination therapy proved to have commendable potential in Helicobacter pylori eradication as compared to already existing conventional and novel drug delivery systems. PMID:19718807

  10. Encapsulation of the herbicide picloram by using polyelectrolyte biopolymers as layer-by-layer materials.

    Science.gov (United States)

    Wang, Xiaojing; Zhao, Jing

    2013-04-24

    Microcapsules of the herbicide picloram (PLR) were formulated by a layer-by-layer (LbL) self-assembly method using the polyelectrolyte biopolymers of biocompatible chitosan (CS) and the UV-absorbent sodium lignosulfonate (SL) as shell materials. The herbicide PLR was recrystallized and characterized using XRD analysis. The obtained PLR-loaded microcapsules were characterized by using SEM, FTIR, CLSM, and ζ-potential measurements. The herbicide loading and encapsulation efficiency were also analyzed for the PLR-loaded microcapsules. The influence of LbL layer numbers on herbicide release and photodegradation rates was investigated in vitro. The results showed that the release rates and photodegradation rates of PLR in microcapsules decreased with increasing number of CS/SL self-assembly layers. The results demonstrated that polyelectrolyte biopolymer-based LbL multilayer microcapsules can be a promising approach for the controlled release of PLR as well as other pesticides with poor photostability or short half-release time.

  11. Nanoporous polyelectrolyte vaccine microcarriers. A formulation platform for enhancing humoral and cellular immune responses.

    Science.gov (United States)

    De Koker, Stefaan; Fierens, Kaat; Dierendonck, Marijke; De Rycke, Riet; Lambrecht, Bart N; Grooten, Johan; Remon, Jean Paul; De Geest, Bruno G

    2014-12-10

    In this paper we report on the design, characterization and immuno-biological evaluation of nanoporous polyelectrolyte microparticles as vaccine carrier. Relative to soluble antigen, formulation of antigen as a sub-10 μm particle can strongly enhance antigen-specific cellular immune responses. The latter is crucial to confer protective immunity against intracellular pathogens and for anti-cancer vaccines. However, a major bottleneck in microparticulate vaccine formulation is the development of generic strategies that afford antigen encapsulation under benign and scalable conditions. Our strategy is based on spray drying of a dilute aqueous solution of antigen, oppositely charged polyelectrolytes and mannitol as a pore-forming component. The obtained solid microparticles can be redispersed in aqueous medium, leading to leaching out of the mannitol, thereby creating a highly porous internal structure. This porous structure enhances enzymatic processing of encapsulated proteins. After optimizing the conditions to process these microparticles we demonstrate that they strongly enhance cross-presentation in vitro by dendritic cells to CD8 T cells. In vivo experiments in mice confirm that this vaccine formulation technology is capable of enhancing cellular immune responses.

  12. Self-Assembled Polyelectrolyte Nanoparticles as Fluorophore-Free Contrast Agents for Multicolor Optical Imaging

    Directory of Open Access Journals (Sweden)

    Da Hye Shin

    2015-03-01

    Full Text Available In this work, we describe the fabrication of self-assembled polyelectrolyte nanoparticles that provide a multicolor optical imaging modality. Poly(γ-glutamic acid(γ-PGA formed self-assembled nanoparticles through electrostatic interactions with two different cationic polymers: poly(L-lysine(PLL and chitosan. The self-assembled γ-PGA/PLL and γ-PGA/chitosan nanoparticles were crosslinked by glutaraldehyde. Crosslinking of the ionic self-assembled nanoparticles with glutaraldehyde not only stabilized the nanoparticles but also generated a strong autofluorescence signal. Fluorescent Schiff base bonds (C=N and double bonds (C=C were generated simultaneously by crosslinking of the amine moiety of the cationic polyelectrolytes with monomeric glutaraldehyde or with polymeric glutaraldehyde. The unique optical properties of the nanoparticles that resulted from the crosslinking by glutaraldehyde were analyzed using UV/Vis and fluorescence spectroscopy. We observed that the fluorescence intensity of the nanoparticles could be regulated by adjusting the crosslinker concentration and the reaction time. The nanoparticles also exhibited high performance in the labeling and monitoring of therapeutic immune cells (macrophages and dendritic cells. These self-assembled nanoparticles are expected to be a promising multicolor optical imaging contrast agent for the labeling, detection, and monitoring of cells.

  13. On the scattering properties of polyelectrolyte gels

    Science.gov (United States)

    Barrat, Jean-Louis; Joanny, Jean-François; Pincus, Phil

    1992-08-01

    We present a simple model for scattering properties of polyelectrolyte gels at swelling equilibrium. In the weak screening limit where the Debye-Hückel screening length is larger than the mesh size of the gel, the direct electrostatic interactions are negligible and the swelling is driven by the osmotic pressure of the counterions. The tension created by this pressure is transmitted through the crosslinks to the elastic chains which behave as isolated chains with an applied force at their end points. The structure factor of the gel can be split into a frozen component due to the average concentration heterogeneities and a thermodynamic component due to concentration fluctuations. The frozen component has a peak at a wavevector of the order of the mesh size of the gel, the thermodynamic component has a peak at a higher wavevector of the order of the inverse transverse radius of the chains. At infinite times the dynamic structure factor relaxes towards the frozen component of the static structure factor. In the limit of small wavevectors the relaxation is diffusive with a diffusion constant equal to the Stokes diffusion constant of the Pincus blobs of the stretched chains. The diffusion constant shows a minimum at a wavevector of the order of the inverse transverse radius of the chains. Nous présentons un modèle simple pour étudier la diffusion de rayonnement par des gels polylectrolytes à l'équilibre de gonflement. Dans la limite d'écrantage faible où la longueur d'écran de Debye-Hückel est plus grande que la maille du gel, les interactions électrostatiques directes sont négligeables et le gonflement est dû à la pression osmotique des contreions. La tension créée par cette pression est transmise par les noeuds du gel aux chaines élastiques qui se comportent comme des chaines isolées avec une force extérieure appliquée aux extrémités. Le facteur de structure du gel est la somme d'une composante gelée due aux hétérogénéités de concentration

  14. Tribological behavior of in situ Ag nanoparticles/polyelectrolyte composite molecular deposition films

    International Nuclear Information System (INIS)

    Multilayer polyelectrolyte films containing silver ions were obtained by molecular deposition method on a glass plate or a quartz substrate. The in situ Ag nanoparticles were synthesized in the multilayer polyelectrolyte films which were put into fresh NaBH4 aqueous solution. The structure and surface morphology of composite molecular deposition films were observed by UV-vis spectrophotometer, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Tribological characteristic was investigated by AFM and micro-tribometer. It was found that the in situ Ag nanoparticles/polyelectrolyte composite molecular deposition films have lower coefficient of friction and higher anti-wear life than pure polyelectrolyte molecular deposition films.

  15. Explicit-ion Effects in the Coil-Globule Transition of Weak Polyelectrolytes

    Science.gov (United States)

    Sikora, Benjamin J.; Whitmer, Jonathan K.

    The first-order coil-globule transition in weak (annealed) polyelectrolytes involves a subtle balance of pH, charge strength, and solvation forces. In this work, we utilize a coarse-grain hybrid grand-canonical Monte Carlo and Molecular Dynamics approach to explore the free energetic topography of a model hydrophobic polybase [representing poly(2-vinylpyridine) (P2VP)] and explore the role of salt concentration/valency in influencing polyelectrolyte conformations using both an implicit Debye-Hückel and explicit salt approach. Our simulations reproduce the experimentally measured behavior for dilute annealed polyelectrolytes, and present a solid foundation for understanding pH responsive polyelectrolyte materials.

  16. Asynchronous Complex Pipeline Design Based on ARM Instruction Set

    Institute of Scientific and Technical Information of China (English)

    WANG Bing; WANG Qin; PENG Rui-hua; FU Yu-zhuo

    2008-01-01

    This paper proposes an asynchronous complex pipeline based on ARM-V3 instruction set. Muller pipeline structure is used as prototype, and the factors which may affect pipeline performance are analyzed. To balance the difficulty of asynchronous design and performance analysis, both complete asynchronous and partial asynchronous structures aere designed and compared. Results of comparison with the well-Rnown industrial product ARM922T verify that about 30% and 40% performance improvement of the partial and complete asynchronous complex pipelines can be obtained respectively. The design methodologies can also be used in the design of other asynchronous pipelines.

  17. Disk-like Tiles Derived from Complex Bases

    Institute of Scientific and Technical Information of China (English)

    Jun LUO; Zuo Ling ZHOU

    2004-01-01

    For each positive integer k, the radix representation of the complex numbers in the base-k + i gives rise to a lattice self-affine tile Tk in the plane, which consists of all the complex numbers that can be expressed in the form ∑j≥1 dj(-k + i)-j, where dj ∈ {0, 1,2,……,k2}. We prove that Tk is homeomorphic to the closed unit disk {z ∈ C: |z| ≤ 1} if and only if k ≠ 2.

  18. Multifunctional polyelectrolyte microcapsules as a contrast agent for photoacoustic imaging in blood.

    Science.gov (United States)

    Yashchenok, Alexey M; Jose, Jithin; Trochet, Philippe; Sukhorukov, Gleb B; Gorin, Dmitry A

    2016-08-01

    The polyelectrolyte microcapsules that can be accurate either visualized in biological media or in tissue would enhance their further in vivo application both as a carrier of active payloads and as a specific sensor. The immobilization of active species, for instance fluorescent dyes, quantum dots, metal nanoparticles, in polymeric shell enables visualization of capsules by optical imaging techniques in aqueous solution. However, for visualization of capsules in complex media an instrument with high contrast modality requires. Herein, we show for the first time photoacoustic imaging (PAI) of multifunctional microcapsules in water and in blood. The microcapsules exhibit greater photoacoustic intensity compare to microparticles with the same composition of polymeric shell presumably their higher thermal expansion. Photoacoustic intensity form microcapsules dispersed in blood displays an enhancement (2-fold) of signal compare to blood. Photoacoustic imaging of microcapsules might contribute to non-invasive carrier visualization and further their in vivo distribution.

  19. Novel measures based on the Kolmogorov complexity for use in complex system behavior studies and time series analysis

    CERN Document Server

    Mihailovic, Dragutin T; Nikolic-Djoric, Emilija; Arsenic, Ilija

    2013-01-01

    We have proposed novel measures based on the Kolmogorov complexity for use in complex system behavior studies and time series analysis. We have considered background of the Kolmogorov complexity and also we have discussed meaning of the physical as well as other complexities. To get better insights into the complexity of complex systems and time series analysis we have introduced the three novel measures based on the Kolmogorov complexity: (i) the Kolmogorov complexity spectrum, (ii) the Kolmogorov complexity spectrum highest value and (iii) the overall Kolmogorov complexity. The characteristics of these measures have been tested using a generalized logistic equation. Finally, the proposed measures have been applied on different time series originating from: the model output (the biochemical substance exchange in a multi-cell system), four different geophysical phenomena (dynamics of: river flow, long term precipitation, indoor 222Rn concentration and UV radiation dose) and economy (stock prices dynamics). Re...

  20. Relation between a Screened Polyelectrolyte and a Field Theory

    CERN Document Server

    Söderberg, B

    1996-01-01

    There exists a generic relationship between the thermodynamics of a continuous polymer with a generic self-interaction and the two-point function of an interacting field-theory. In addition, the (2N)-point function of the resulting field theory is similarly related to a system of N interacting polymers. In the present paper, this relation is explored for the special case of a polyelectrolyte, characterized by a screened Coulomb pair potential. The corresponding field theory can be recast in a particularly simple form, corresponding to a quantum-mechanical particle, self-interacting via the emission and absorption of a massive scalar field. This is particularly useful in a perturbative treatment: perturbative expansions for the polyelectrolyte can be simply derived from the loop expansion for the related field-theoretical two-point function, for which established computational methods exist.

  1. Weak Polyelectrolyte-Clay Assemblies: Physical Mechanisms of Biological Response

    Science.gov (United States)

    Sukhishvili, Svetlana; Pavlukhina, Svetlana; Zhuk, Iryna

    2014-03-01

    We report on a highly efficient, non-leachable antibacterial coating, consisting of an ultrathin nanocomposite hydrogel capable of hosting, protecting and delivering antibiofilm agents in response to bacterial infection. Constructed using layer-by-layer (LbL) deposition of clay nanoplatelets and a weak polyelectrolyte and loaded with an antimicrobial agent (AmA), the coatings was highly resistant to colonization by Staphylococcus aureus. The high antibiofilm activity of the coating results from a combination of highly localized, bacteria-triggered AmA release and hydrogel swelling, as well as retention of AmA by clay nanoplatelets. We discuss the dependence of rheological and swelling properties of weak polyelectrolyte-clay assemblies on film thickness, clay platelet orientation and environmental pH.

  2. Porphyrin Diacid-Polyelectrolyte Assemblies: Effective Photocatalysts in Solution

    Directory of Open Access Journals (Sweden)

    Sabine Frühbeißer

    2016-05-01

    Full Text Available Developing effective and versatile photocatalytic systems is of great potential in solar energy conversion. Here we investigate the formation of supramolecular catalysts by electrostatic self-assembly in aqueous solution: Combining positively charged porphyrins with negatively charged polyelectrolytes leads to nanoscale assemblies where, next to electrostatic interactions, π–π interactions also play an important role. Porphyrin diacid-polyelectrolyte assemblies exhibit a substantially enhanced catalytic activity for the light-driven oxidation of iodide. Aggregates with the hexavalent cationic porphyrin diacids show up to 22 times higher catalytic activity than the corresponding aggregates under neutral conditions. The catalytic activity can be increased by increasing the valency of the porphyrin and by choice of the loading ratio. The structural investigation of the supramolecular catalysts took place via atomic force microscopy and small angle neutron scattering. Hence, a new facile concept for the design of efficient and tunable self-assembled photocatalysts is presented.

  3. Determination of three characteristic regimes of weakly charged polyelectrolytes monolayers

    International Nuclear Information System (INIS)

    We have demonstrated that monolayer films of randomly charged polystyrene sulfonated acid (PSSA) can be produced by the Langmuir technique, and observed the micro-domain structures, produced by the phase separation of electrostatically charged moieties and the hydrophobic moieties. Using atomic force microscopy and Langmuir isotherm, we found three specific regimes for the polyelectrolytes with various degrees of sulfonation (4-35%); very low charged PSSA (4-5%) in the hydrophobic regime, moderately charged PSSA (6-16%) which possessed a well-balanced nature between electrostatic and the hydrophobic interactions, and strongly amphiphilic nature of PSSA (6-16%) in the ionomer regime. Finally, we could categorize PSSA 35% in the polyelectrolyte regime, due to the dominance of the electrostatic interactions over the hydrophobic interactions

  4. Aqueous dispersions of silver nanoparticles in polyelectrolyte solutions

    Indian Academy of Sciences (India)

    Dan Donescu; Raluca Somoghi; Marius Ghiurea; Raluca Ianchis; Cristian Petcu; Stefania Gavriliu; Magdalena Lungu; Claudia Groza; Carmen R Ionescu; Carmen Panzaru

    2013-03-01

    In this report, we present the versatile and effective technique, using environmental friendly reductant glucose, to prepare stable silver nanodispersions by reduction of Ag+ ions. Alternant copolymers of maleic anhydride with vinyl acetate and styrene sulphonate sodium acid salt polyelectrolytes were synthesized in aqueous solution and used as stabilizers. The formation of nano silver particles was confirmed by UV-Vis spectrophotometry and TEM measurements. Dynamic Light Scattering (DLS) measurements were needed to study how the reagents and their concentrations influence particle size. SEM images show the nanostructure of the hybrid films and indicate a strong interaction between the polyelectrolyte and the silver NPs. Moreover, the silver NPs could be stored for one year without observation of aggregates or sedimentation. The final solid products obtained after evaporating to dryness can be used to produce stable dispersions upon mixing with water. Few of the final products were found to exhibit a high antibacterial and antifungal activity.

  5. Interaction of Fluorocarbon Containing Hydrophobically Modified Polyelectrolyte with Nonionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    GUO,Jin-Feng(郭金峰); ZHUANG,Dong-Qing(庄东青); ZHOU,Hui(周晖); ZHANG,Yun-Xiang(章云祥)

    2002-01-01

    The interaction of fluorocarbon containing hydrophobically modified polyelectrolyte (FMPAANa) with two kinds of nonionic surfactants (hydrogenated and fluorinated) in a semidilute (0.5 wt% ) aqueous solution had been studied by rheological measurements. Association behavior was found in both systems. The hydrophobic interaction of FMPAANa with fluorinated surfactant (FC171) is much stronger than that with hydrogenated surfactant (NP7.5) at low surfactant concentrations. The interaction is strengthened by surfactants being added for the density of active junctions increased. Whereas distinct phenomena for FC171 and NP7. 5 start to be found as the surfactants added over their respective certain concentration. The interaction of polyelectrolyte with fluorinated surfactant increases dramatical ly while that with hydrogenated surfactant decreases.

  6. Entering and exiting the protein-polyelectrolyte coacervate phase via nonmonotonic salt dependence of critical conditions.

    Science.gov (United States)

    Antonov, Margarita; Mazzawi, Malek; Dubin, Paul L

    2010-01-11

    Critical conditions for coacervation of poly(dimethyldiallylammonium chloride) (PDADMAC) with bovine serum albumin were determined as a function of ionic strength, pH, and protein/polyelectrolyte stoichiometry. The resultant phase boundaries, clearly defined with this narrow molecular weight distribution PDADMAC sample, showed nonmonotonic ionic strength dependence, with the pH-induced onset of coacervation (at pH(phi)) occurring most readily at 20 mM NaCl. The corresponding onset of soluble complex formation, pH(c), determined using high-precision turbidimetry sensitive to changes of less than 0.1% transmittance units, mirrored the ionic strength dependence of pH(phi). This nonmonotonic binding behavior is attributable to simultaneous screening of short-range attraction and long-range repulsion. The similarity of pH(c) and pH(phi) was explained by the effect of salt on protein binding, and consequently on the number of bound proteins relative to that required for charge neutralization of the complex, a requirement for phase separation. Expansion of the coacervation regime with chitosan, a polycation with charge spacing similar to that of PDADMAC, could be due to either the charge mobility or chain stiffness of the former. The pH(phi) versus I phase boundary for PDADMAC correctly predicted entrance into and egress from the coacervation region by addition of either salt or water. The ability to induce or suppress coacervation via protein/polyelectrolyte stoichiometry r was found to be consistent with the proposed model. The results indicate that the conjoint effects of I, r, and pH on coacervation could be represented by a three-dimensional phase boundary.

  7. A new entropy based method for computing software structural complexity

    CERN Document Server

    Roca, J L

    2002-01-01

    In this paper a new methodology for the evaluation of software structural complexity is described. It is based on the entropy evaluation of the random uniform response function associated with the so called software characteristic function SCF. The behavior of the SCF with the different software structures and their relationship with the number of inherent errors is investigated. It is also investigated how the entropy concept can be used to evaluate the complexity of a software structure considering the SCF as a canonical representation of the graph associated with the control flow diagram. The functions, parameters and algorithms that allow to carry out this evaluation are also introduced. After this analytic phase follows the experimental phase, verifying the consistency of the proposed metric and their boundary conditions. The conclusion is that the degree of software structural complexity can be measured as the entropy of the random uniform response function of the SCF. That entropy is in direct relation...

  8. Theory of volume transition in polyelectrolyte gels with charge regularization

    OpenAIRE

    Hua, Jing; Mitra, Mithun K; Muthukumar, M.

    2012-01-01

    We present a theory for polyelectrolyte gels that allow the effective charge of the polymer backbone to self-regulate. Using a variational approach, we obtain an expression for the free energy of gels that accounts for the gel elasticity, free energy of mixing, counterion adsorption, local dielectric constant, electrostatic interaction among polymer segments, electrolyte ion correlations, and self-consistent charge regularization on the polymer strands. This free energy is then minimized to p...

  9. Electrochemical metal speciation in natural and model polyelectrolyte systems.

    OpenAIRE

    Hoop, van den, M.A.G.T.

    1994-01-01

    The purpose of the research described in this thesis was to examine the applicability of electro-analytical techniques in obtaining information on the speciation of metals, i.e. their distribution over different physico-chemical forms, in aquatic systems containing charged macromolecules. In chapter 1 a general introduction is given to (i) metal speciation in aquatic systems, (ii) (bio)polyelectrolytes and their counterion distributions and (iii) electrochemical methods emphasizing their apll...

  10. Hydration of polyelectrolytes studied by molecular dynamics simulation

    OpenAIRE

    Biermann, Oliver; Haedicke, Erich; Koltzenburg, Sebastian; Seufert, Michael; Mueller-Plathe, Florian

    2001-01-01

    Molecular dynamics simulations of diluted (~2.5 weight percent) aqueous solutions of two polyelectrolytes, namely sodium carboxy methyl cellulose (CMC) and sodium poly(acrylate) (PAA) have been performed. Water and counterions were taken into account explicitly. For CMC the substitution pattern and starting conformation is all-important. Two simulations of CMC oligomers resulted in different structures: One molecule takes a stretched conformation, while the second one keeps a globule-like, to...

  11. Foaming binary solution mixtures of low molecular surfactant and polyelectrolyte

    OpenAIRE

    Aidarova, S. B.; Musabekov, K. B.; Ospanova, Z. B.; Güden, Mustafa

    2006-01-01

    The lifetime of water solution foams of sodium dodecylsulfate (DDS, low molecular weight surfactant) and sodium carboxymethylcellulose (SCMC, polyelectrolyte) and their binary mixtures was experimentally investigated. The effects of ionic strength and acidity on the foam life were also determined. In binary solutions, a synergic effect of DDS and SCMC on the surface tension reduction, most likely resulting from the interaction of the surfactant with polymer, was found. The addition of NaCl in...

  12. Structure of strongly interacting polyelectrolyte diblock copolymer micelles

    OpenAIRE

    Korobko, A.V.; Jesse, W.; Lapp, A.; Egelhaaf, S. U.; van der Maarel, J. R. C.

    2004-01-01

    The structure of spherical micelles of the diblock poly(styrene-block-acrylic acid) [PS-b-PA] copolymer in water was investigated up to concentrations where the polyelectrolyte coronal layers have to shrink and/or interpenetrate in order to accommodate the micelles in the increasingly crowded volume. We obtained the partial structure factors pertaining to the core and corona density correlations with small angle neutron scattering (SANS) and contrast matching in the water. The counterion stru...

  13. Antifouling Properties of Smooth and Structured Polyelectrolyte Thin Films

    OpenAIRE

    Cao, Xinyu

    2008-01-01

    The goal of this thesis is the development of smooth and structured polyelectrolyte surfaces and to correlate the surface properties with their antifouling performance. Strategies in antifouling are focused on two aspects: surface chemistry and surface topography. Therefore, two types of surfaces, polysaccharide coatings with different chemistries and poly(acrylic acid)/polyethylenimine multilayers with different topographies, have been studied in this thesis. Three polysaccharides, hyaluroni...

  14. Salt-Induced Counterion-Mobility Anomaly in Polyelectrolyte Electrophoresis

    OpenAIRE

    Fischer, Sebastian; Naji, Ali; Netz, Roland R.

    2009-01-01

    We study the electrokinetics of a single polyelectrolyte chain in salt solution using hydrodynamic simulations. The salt-dependent chain mobility compares well with experimental DNA data. The mobility of condensed counterions exhibits a salt-dependent change of sign, an anomaly that is also reflected in the counterion excess conductivity. Using Green's function techniques this anomaly is explained by electrostatic screening of the hydrodynamic interactions between chain and counterions.

  15. Kinetics of swelling of polyelectrolyte gels: Fixed degree of ionization

    Science.gov (United States)

    Sen, Swati; Kundagrami, Arindam

    2015-12-01

    The swelling kinetics of uncharged and charged polymer (polyelectrolyte) gels in salt-free conditions is studied in one dimension by solving the constitutive equation of motion (Newton's law for the elementary gel volume) of the displacement variable by two theoretical methods: one in which the classical definition of stress is used with the bulk modulus taken as a parameter, and the other in which a phenomenological expression of the osmotic stress as a function of polymer density and degree of ionization is taken as an input to the dynamics. The time-evolution profiles for spatially varying polymer density and stress, along with the location of the gel-solvent interface, are obtained from the two methods. We show that both the polymer density (volume fraction) and stress inside the gel follow expected behaviours of being maximum for the uniformly shrunken gel, and relaxing slowly to the lowest values as the gel approaches equilibrium. We further show that, by comparing the temporal profiles of the gel-solvent interface and other variables between the two methods, one may attempt to assign an effective bulk modulus to the polyelectrolyte gel as a function of the degree of ionization and other parameters of the gel such as hydrophobicity, cross-link density, and the temperature. The major result we get is that the effective bulk modulus of a polyelectrolyte gel increases monotonically with its degree of ionization. In the process of identifying the parameters for a monotonic swelling, we calculated using a well-known expression of the free energy the equilibrium results of two-phase co-existence and the critical point of a polyelectrolyte gel with a fixed degree of ionization.

  16. Kinetics of swelling of polyelectrolyte gels: Fixed degree of ionization

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Swati; Kundagrami, Arindam, E-mail: arindam@iiserkol.ac.in [Department of Physical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur 741246, West Bengal (India)

    2015-12-14

    The swelling kinetics of uncharged and charged polymer (polyelectrolyte) gels in salt-free conditions is studied in one dimension by solving the constitutive equation of motion (Newton’s law for the elementary gel volume) of the displacement variable by two theoretical methods: one in which the classical definition of stress is used with the bulk modulus taken as a parameter, and the other in which a phenomenological expression of the osmotic stress as a function of polymer density and degree of ionization is taken as an input to the dynamics. The time-evolution profiles for spatially varying polymer density and stress, along with the location of the gel-solvent interface, are obtained from the two methods. We show that both the polymer density (volume fraction) and stress inside the gel follow expected behaviours of being maximum for the uniformly shrunken gel, and relaxing slowly to the lowest values as the gel approaches equilibrium. We further show that, by comparing the temporal profiles of the gel-solvent interface and other variables between the two methods, one may attempt to assign an effective bulk modulus to the polyelectrolyte gel as a function of the degree of ionization and other parameters of the gel such as hydrophobicity, cross-link density, and the temperature. The major result we get is that the effective bulk modulus of a polyelectrolyte gel increases monotonically with its degree of ionization. In the process of identifying the parameters for a monotonic swelling, we calculated using a well-known expression of the free energy the equilibrium results of two-phase co-existence and the critical point of a polyelectrolyte gel with a fixed degree of ionization.

  17. The effects of self-assembly in solutions of polyelectrolytes

    OpenAIRE

    Limberger, Roman E.

    2004-01-01

    The PhD thesis "The Effects of Self-Assembly in Solutions of Polyelectrolytes" written by Roman E. Limberger contains the introduction, the literature review, two original parts, the consequences, the acknowledgements, the list of references and four appendices. In the introduction the relevance of the present thesis is explained. The literature review is divided into two parts. The first part is dedicated to the consideration of the main theoretical models and the results in the study of...

  18. Critical Adsorption of Polyelectrolytes onto Charged Spherical Colloids

    OpenAIRE

    Winkler, R. G.; Cherstvy, A. G.

    2006-01-01

    The adsorption of a flexible polyelectrolyte in a salt solution onto an oppositely charged spherical surface is investigated. An analytical solution is derived, which is valid for any sphere radius and consistently recovers the result of a planar surface in the limit of large sphere radii, by substituting the Debye-Huckel potential via the Hulthen potential. Expressions for critical quantities such as the critical radius and the critical surface charge density are provide. A comparison of our...

  19. Interactions of microfibrillated cellulose and cellulosic fines with cationic polyelectrolytes

    OpenAIRE

    Taipale, Tero

    2010-01-01

    The overall aim of this work was to produce and characterize different types of cellulosic fines and microfibrillated cellulose; to study their interactions with high molar mass cationic polyelectrolytes; and to demonstrate novel examples of their utilization. The work was performed, and its results discussed mainly from papermaking point of view, but the results are also well applicable in other fields of industry. Cellulosic fines are an essential component of papermaking fiber suspens...

  20. Adsorption of highly charged Gaussian polyelectrolytes to oppositely charged surfaces

    OpenAIRE

    Dutta, Sandipan; Jho, Y. S.

    2015-01-01

    In many biological processes highly charged biomolecules are adsorbed into oppositely charged surfaces of macroions and membranes. They form strongly correlated structures close to the surface which can not be explained by the conventional Poisson-Boltzmann theory. Many of the flexible biomolecules can be described by Gaussian polymers. In this work strong coupling theory is used to study the adsorption of highly charged Gaussian polyelectrolytes. Two cases of adsorptions are considered, when...

  1. A Modified Random Phase Approximation of Polyelectrolyte Solutions

    OpenAIRE

    Ermoshkin, A. V.; de la Cruz, M. Olvera

    2002-01-01

    We compute the phase diagram of salt-free polyelectrolyte solutions using a modified Debye-Huckel Approach. We introduce the chain connectivity via the Random Phase Approximation with two important modifications. We modify the electrostatic potential at short distances to include a bound on the electrostatic attractions at the distance of closest approach between charges. This modification is shown to act as a hard core in the phase diagram of electrolyte solutions. We also introduce a cut-of...

  2. Polyelectrolytes in the presence of multivalent ions: gelation versus segregation

    OpenAIRE

    Ermoshkin, A. V.; de la Cruz, M. Olvera

    2002-01-01

    We analyze solutions of strongly charged chains bridged by linkers such as multivalent ions. The gelation induced by the strong short range electrostatic attractions is dramatically suppressed by the long range electrostatic correlations due to the charge along the uncrosslinked monomers and ions. A modified Debye-Huckel approach of crosslinked clusters of charged chains is used to determined the mean field gelation transition self-consistently. Highly dilute polyelectrolyte solutions tend to...

  3. Highly active antibody-modified magnetic polyelectrolyte capsules.

    Science.gov (United States)

    Valdepérez, Daniel; Del Pino, Pablo; Sánchez, Lourdes; Parak, Wolfgang J; Pelaz, Beatriz

    2016-07-15

    Polyelectrolyte hollow capsules are versatile platforms typically used for encapsulation of a wide variety of macromolecules in their cavity. The polymer shell of these capsules as composed by alternating layers of oppositely charged polyelectrolytes also allows for adding additional functionalities. The properties of the shell can be for example engineered by trapping different nanoparticles in-between the shell layers and/or by attaching bioactive molecules such as antibodies to the outermost layer. Herein, iron oxide NPs were inmobilized into the shell of polyelectrolyte capsules and the outermost layer of the shell was covalently modified with anti peroxidase antibodies. These capsules act as prototype model system, aiming to obtain a microstructure with the potential capability to specifically recognize and separate macromolecules. Due to the magnetic nanoparticles in the capsule shell, the capsules together with the attached target might be extracted by magnetic field gradients. Here we verified this approach by extracting horseradish peroxidase from a solution through magnetic separation with capsules bearing antibodies against horseradish peroxidase. The bioactivity of the capsules and the high degree of specific antibody functionalization were confirmed and quantified through an enzymatic reaction mediated by the extracted horseradish peroxidase. PMID:27089014

  4. DLVO theory for like-charged polyelectrolyte and surface interactions

    International Nuclear Information System (INIS)

    The mechanism of adsorption of charged polymers onto like-charged surfaces has been a matter of debates in recent years. We propose a mean-field theory for the interactions of like-charged polyelectrolyte and a plane surface in the presence of 1:1 and 2:1 electrolyte, which takes into account long-range van der Waals and double-layer forces. The theory is able to predict the optimum conditions, such as solvent composition, pH and temperature, for polyelectrolyte adsorption on like-charged surfaces as well as to account for the conformational properties of a polymer at the surfaces. An excellent agreement of the predictions of the theory with the available experimental data suggests that it can be used as a simple tool for predicting the optimum conditions for studying various polyelectrolyte properties, including their biological activity, at the surfaces. Particularly simple expressions for the polymer/surface interaction energy have been obtained in the Debye-Huckel limit. The applicability of this approximation to the biological molecules at the surfaces is discussed

  5. Charged colloids and polyelectrolytes: from statics to electrokinetics

    International Nuclear Information System (INIS)

    A review is given on recent studies of charged colloidal suspensions and polyelectrolytes both in static and non-equilibrium situations. As far as static equilibrium situations are concerned, we discuss three different problems: 1) Sedimentation density profiles in charged suspensions are shown to exhibit a stretched non-bariometric wing at large heights and binary suspensions under gravity can exhibit an analog of the brazil-nut effect known from granular matter, i.e. the heavier particles settle on top of the lighter ones. 2) Soft polyelectrolyte systems like polyelectrolyte stars and microgels show an ultra-soft effective interaction and this results into an unusual equilibrium phase diagram including reentrant melting transitions and stable open crystalline lattices. 3) The freezing transition in bilayers of confined charged suspensions is discussed and a reentrant behaviour is obtained. As far as nonequilibrium problems are concerned, we discuss an interface instability in oppositely driven colloidal mixtures and discuss possible approaches to simulate electrokinetic effects in charged suspensions

  6. Exploration of polyelectrolytes as draw solutes in forward osmosis processes

    KAUST Repository

    Ge, Qingchun

    2012-03-01

    The development of the forward osmosis (FO) process has been constrained by the slow development of appropriate draw solutions. Two significant concerns related to draw solutions are the draw solute leakage and intensiveenergy requirement in recycling draw solutes after the FO process. FO would be much attractive if there is no draw solute leakage and the recycle of draw solutes is easy and economic. In this study, polyelectrolytes of a series of polyacrylic acid sodium salts (PAA-Na), were explored as draw solutes in the FO process. The characteristics of high solubility in water and flexibility in structural configuration ensure the suitability of PAA-Na as draw solutes and their relative ease in recycle through pressure-driven membrane processes. The high water flux with insignificant salt leakage in the FO process and the high salt rejection in recycle processes reveal the superiority of PAA-Na to conventional ionic salts, such as NaCl, when comparing their FO performance via the same membranes. The repeatable performance of PAA-Na after recycle indicates the absence of any aggregation problems. The overall performance demonstrates that polyelectrolytes of PAA-Na series are promising as draw solutes, and the new concept of using polyelectrolytes as draw solutes in FO processes is applicable. © 2011 Elsevier Ltd.

  7. Complex-wave retrieval based on blind signal separation

    Institute of Scientific and Technical Information of China (English)

    Xiaodong Chai; Chengpeng Zhou; Zhaoyan Feng; Yinhua Wang; Yansheng Zuo

    2006-01-01

    In the process of the reconstruction of digital holography, the traditional methods of diffraction and filtration are commonly adopted to recover the original complex-wave signal. Influenced by twin-image and zero-order terms, the above-mentioned methods, however, either limit the field of vision or result in the loss of the amplitude and phase. A new method for complex-wave retrieval is presented, which is based on blind signal separation. Three frames of holograms are captured by a charge coupled device (CCD)camera to form an observation signal. The term containing only amplitude and phase of complex-wave is separated, by means of independent component analysis, from the observation signal, which effectively eliminates the zero-order term. Finally, the complex-wave retrieval of pure phase wavefront is achieved.Experimental results show that this method can better recover the amplitude and phase of the original complex-wave even when there is a frequency spectrum mixture in the hologram.

  8. Influence of polyelectrolyte multilayer coating on the degree and type of biofouling in freshwater environment.

    Science.gov (United States)

    Frueh, Johannes; Gai, Meiyu; Yang, Zhibo; He, Qiang

    2014-06-01

    Biofouling is one of the biggest problems of water-borne systems. Since not only marine but also freshwater-based structures are affected, the biofouling in this environment is studied. The focus of this study lies on the antifouling properties of novel coating materials like polyelectrolyte multilayers (PEM) compared with currently used silicon rubber (PDMS) based fouling release coatings. The following article contains the results of a systematical screening of the mechanical, surface charge and surface nano-heterogeneous properties of the investigated PEM and PDMS systems. The results show that negatively charged non crosslinked and crosslinked PEM coated PDMS can surpass current PDMS based fouling release coatings. The PEM films are not only able to reduce the biofouling, but are additionally able to control the type of settled bacteria (gram positive or negative). The negative terminated surfaces inhibit the settlement of gram positive bacteria, whereby the positive terminated surfaces inhibit the settlement of gram negative bacteria. PMID:24738394

  9. Low-Complexity Geometry-Based MIMO Channel Simulation

    Directory of Open Access Journals (Sweden)

    Christoph W. Ueberhuber

    2007-01-01

    Full Text Available The simulation of electromagnetic wave propagation in time-variant wideband multiple-input multiple-output mobile radio channels using a geometry-based channel model (GCM is computationally expensive. Due to multipath propagation, a large number of complex exponentials must be evaluated and summed up. We present a low-complexity algorithm for the implementation of a GCM on a hardware channel simulator. Our algorithm takes advantage of the limited numerical precision of the channel simulator by using a truncated subspace representation of the channel transfer function based on multidimensional discrete prolate spheroidal (DPS sequences. The DPS subspace representation offers two advantages. Firstly, only a small subspace dimension is required to achieve the numerical accuracy of the hardware channel simulator. Secondly, the computational complexity of the subspace representation is independent of the number of multipath components (MPCs. Moreover, we present an algorithm for the projection of each MPC onto the DPS subspace in 𝒪(1 operations. Thus the computational complexity of the DPS subspace algorithm compared to a conventional implementation is reduced by more than one order of magnitude on a hardware channel simulator with 14-bit precision.

  10. Dynamics of polyelectrolyte adsorption on surfaces: Applications in the detection of iron in water

    Science.gov (United States)

    Gammana, Madhira N.

    presented in this thesis. It was found that the amount and rate of Fe3+ uptake was dependent on the relative size of each block in the polymer and the degree of reaction of DFB with the adsorbed layer. In particular, higher amounts and higher rates were obtained when the density of DFB was lowered. This shows that the DFB was sterically hindered from forming a hexacoordinate complex with Fe3+ by the presence of neighboring DFB molecules. This is a key factor that needs to be considered in developing Fe3+ detection systems based on siderophores anchored to surfaces.

  11. Complexity and agent-based modelling in urban research

    DEFF Research Database (Denmark)

    Fertner, Christian

    Urbanisation processes are results of a broad variety of actors or actor groups and their behaviour and decisions based on different experiences, knowledge, resources, values etc. The decisions done are often on a micro/individual level but resulting in macro/collective behaviour. In urban research...... influence on the bigger system. Traditional scientific methods or theories often tried to simplify, not accounting complex relations of actors and decision-making. The introduction of computers in simulation made new approaches in modelling, as for example agent-based modelling (ABM), possible, dealing...... of complexity for a majority of science, there exists a huge number of scientific articles, books, tutorials etc. to these topics which doesn’t make it easy for a novice in the field to find the right literature. The literature used gives an optimistic outlook for the future of this methodology, although ABM...

  12. Audiovisual Quality Fusion based on Relative Multimodal Complexity

    DEFF Research Database (Denmark)

    You, Junyong; Korhonen, Jari; Reiter, Ulrich

    2011-01-01

    In multimodal presentations the perceived audiovisual quality assessment is significantly influenced by the content of both the audio and visual tracks. Based on our earlier subjective quality test for finding the optimal trade-off between audio and video quality, this paper proposes a novel method...... for relative multimodal complexity analysis to derive the fusion parameter in objective audiovisual quality metrics. Audio and video qualities are first estimated separately using advanced quality models, and then they are combined into the overall audiovisual quality using a linear fusion. Based on carefully...... designed auditory and visual features, the relative complexity analysis model across sensory modalities is proposed for deriving the fusion parameter. Experimental results have demonstrated that the content adaptive fusion parameter can improve the prediction accuracy of objective audiovisual quality...

  13. Next frontier in agent-based complex automated negotiation

    CERN Document Server

    Ito, Takayuki; Zhang, Minjie; Robu, Valentin

    2015-01-01

    This book focuses on automated negotiations based on multi-agent systems. It is intended for researchers and students in various fields involving autonomous agents and multi-agent systems, such as e-commerce tools, decision-making and negotiation support systems, and collaboration tools. The contents will help them to understand the concept of automated negotiations, negotiation protocols, negotiating agents’ strategies, and the applications of those strategies. In this book, some negotiation protocols focusing on the multiple interdependent issues in negotiations are presented, making it possible to find high-quality solutions for the complex agents’ utility functions. This book is a compilation of the extended versions of the very best papers selected from the many that were presented at the International Workshop on Agent-Based Complex Automated Negotiations.

  14. Complexation Between Cationic Diblock Copolymers and Plasmid DNA

    Science.gov (United States)

    Jung, Seyoung; Reineke, Theresa; Lodge, Timothy

    Deoxyribonucleic acids (DNA), as polyanions, can spontaneously bind with polycations to form polyelectrolyte complexes. When the polycation is a diblock copolymer with one cationic block and one uncharged hydrophilic block, the polyelectrolyte complexes formed with plasmid DNA (pDNA) are often colloidally stable, and show great promise in the field of polymeric gene therapy. While the resulting properties (size, stability, and toxicity to biological systems) of the complexes have been studied for numerous cationic diblocks, the fundamentals of the pDNA-diblock binding process have not been extensively investigated. Herein, we report how the cationic block content of a diblock influences the pDNA-diblock interactions. pDNA with 7164 base pairs and poly(2-deoxy-2-methacrylamido glucopyranose)-block-poly(N-(2-aminoethyl) methacrylamide) (PMAG-b-PAEMA) are used as the model pDNA and cationic diblock, respectively. To vary the cationic block content, two PMAG-b-PAEMA copolymers with similar PMAG block lengths but distinct PAEMA block lengths and a PAEMA homopolymer are utilized. We show that the enthalpy change from pDNA-diblock interactions is dependent on the cationic diblock composition, and is closely associated with both the binding strength and the pDNA tertiary structure.

  15. Recognition of protein complexation based on hydrophobicity distribution

    OpenAIRE

    Banach, Mateusz; Roterman, Irena

    2009-01-01

    The identification of the surface area able to generate the protein-protein complexation ligand and ion ligation is critical for the recognition of the biological function of particular proteins. The technique based on the analysis of the irregularity of hydrophobicity distribution is used as the criterion for the recognition of the interaction regions. Particularly, the exposure of hydrophobic residues on the surface of protein as well as the localization of the hydrophilic residues in the h...

  16. Clustering based segmentation of text in complex color images

    Institute of Scientific and Technical Information of China (English)

    毛文革; 王洪滨; 张田文

    2004-01-01

    We propose a novel scheme based on clustering analysis in color space to solve text segmentation in complex color images. Text segmentation includes automatic clustering of color space and foreground image generation. Two methods are also proposed for automatic clustering: The first one is to determine the optimal number of clusters and the second one is the fuzzy competitively clustering method based on competitively learning techniques. Essential foreground images obtained from any of the color clusters are combined into foreground images. Further performance analysis reveals the advantages of the proposed methods.

  17. A BRB Based Fault Prediction Method of Complex Electromechanical Systems

    Directory of Open Access Journals (Sweden)

    Bangcheng Zhang

    2015-01-01

    Full Text Available Fault prediction is an effective and important approach to improve the reliability and reduce the risk of accidents for complex electromechanical systems. In order to use the quantitative information and qualitative knowledge efficiently to predict the fault, a new model is proposed on the basis of belief rule base (BRB. Moreover, an evidential reasoning (ER based optimal algorithm is developed to train the fault prediction model. The screw failure in computer numerical control (CNC milling machine servo system is taken as an example and the fault prediction results show that the proposed method can predict the behavior of the system accurately with combining qualitative knowledge and some quantitative information.

  18. Trajectory-Based Complexity (TBX): A Modified Aircraft Count to Predict Sector Complexity During Trajectory-Based Operations

    Science.gov (United States)

    Prevot, Thomas; Lee, Paul U.

    2011-01-01

    In this paper we introduce a new complexity metric to predict -in real-time- sector complexity for trajectory-based operations (TBO). TBO will be implemented in the Next Generation Air Transportation System (NextGen). Trajectory-Based Complexity (TBX) is a modified aircraft count that can easily be computed and communicated in a TBO environment based upon predictions of aircraft and weather trajectories. TBX is scaled to aircraft count and represents an alternate and additional means to manage air traffic demand and capacity with more consideration of dynamic factors such as weather, aircraft equipage or predicted separation violations, as well as static factors such as sector size. We have developed and evaluated TBX in the Airspace Operations Laboratory (AOL) at the NASA Ames Research Center during human-in-the-loop studies of trajectory-based concepts since 2009. In this paper we will describe the TBX computation in detail and present the underlying algorithm. Next, we will describe the specific TBX used in an experiment at NASA's AOL. We will evaluate the performance of this metric using data collected during a controller-inthe- loop study on trajectory-based operations at different equipage levels. In this study controllers were prompted at regular intervals to rate their current workload on a numeric scale. When comparing this real-time workload rating to the TBX values predicted for these time periods we demonstrate that TBX is a better predictor of workload than aircraft count. Furthermore we demonstrate that TBX is well suited to be used for complexity management in TBO and can easily be adjusted to future operational concepts.

  19. Implementation of non-uniform FFT based Ewald summation in Dissipative Particle Dynamic method

    CERN Document Server

    Wang, Yong-Lei; Lu, Zhong-Yuan; 10.1016/j.jcp.2012.09.023

    2013-01-01

    The ENUF method, i.e., Ewald summation based on the Non-Uniform FFT technique (NFFT), is implemented in Dissipative Particle Dynamics (DPD) simulation scheme to fast and accurately calculate the electrostatic interactions at mesoscopic level. In a simple model electrolyte system, the suitable ENUF-DPD parameters, including the convergence parameter $\\alpha$, the NFFT approximation parameter $p$, and the cut-offs for real and reciprocal space contributions, are carefully determined. With these optimized parameters, the ENUF-DPD method shows excellent efficiency and scales as $\\mathcal{O}(N\\log N)$. The ENUF-DPD method is further validated by investigating the effects of charge fraction of polyelectrolyte, ionic strength and counterion valency of added salts on polyelectrolyte conformations. The simulations in this paper, together with a separately published work of dendrimer-membrane complexes, show that the ENUF-DPD method is very robust and can be used to study charged complex systems at mesoscopic level.

  20. Adsorption et rhéologie interfaciale de complexes polyélectrolytes-tensioactifs

    OpenAIRE

    Monteux, Cécile

    2004-01-01

    The first part of this thesis is an experimental study of the adsorption of oppositely charged surfactant/polyelectrolyte complexes at the air-water interface using ellipsometry, surface tension and observation of foam-film drainage. The complexes can form hydrophobic globules that adsorb in heterogeneous and thick layers rearranging very slowly. The structure and thickness of these layers depends on the ratio of surfactant to polyelectrolyte concentrations as well as the hydrophobicity of th...

  1. Adsorption of polyelectrolytes at liquid-liquid interfaces and its effect on

    NARCIS (Netherlands)

    Boehm, J.T.C.

    1974-01-01

    In this study we have investigated the adsorption behaviour of a number of synthetic polyelectrolytes at the paraffin oil-water interface and the properties of paraffin oil-in-water emulsions stabilized by these polyelectrolytes.Polyacrylic acid (PAA), polymethacrylic acid (PMA) and the copolymers o

  2. Inferring drug-disease associations based on known protein complexes.

    Science.gov (United States)

    Yu, Liang; Huang, Jianbin; Ma, Zhixin; Zhang, Jing; Zou, Yapeng; Gao, Lin

    2015-01-01

    Inferring drug-disease associations is critical in unveiling disease mechanisms, as well as discovering novel functions of available drugs, or drug repositioning. Previous work is primarily based on drug-gene-disease relationship, which throws away many important information since genes execute their functions through interacting others. To overcome this issue, we propose a novel methodology that discover the drug-disease association based on protein complexes. Firstly, the integrated heterogeneous network consisting of drugs, protein complexes, and disease are constructed, where we assign weights to the drug-disease association by using probability. Then, from the tripartite network, we get the indirect weighted relationships between drugs and diseases. The larger the weight, the higher the reliability of the correlation. We apply our method to mental disorders and hypertension, and validate the result by using comparative toxicogenomics database. Our ranked results can be directly reinforced by existing biomedical literature, suggesting that our proposed method obtains higher specificity and sensitivity. The proposed method offers new insight into drug-disease discovery. Our method is publicly available at http://1.complexdrug.sinaapp.com/Drug_Complex_Disease/Data_Download.html.

  3. Field theoretic simulations of the interfacial properties of complex coacervates

    Science.gov (United States)

    Riggleman, Robert; Fredrickson, Glenn

    2011-03-01

    Many biological processes and emerging technologies, such as wet adhesives and biosensors, rely on the association between oppositely charged polyelectrolytes. Such association is driven not only by the electrostatic interactions between the polyelectrolytes, but there is also a substantial entropy gain associated with counterion release upon complexation. In some cases, the association between oppositely charged polymers can lead to a solid precipitate while others can result in a fluid phase rich in polyelectrolytes (coacervate phase) coexisting with a polyelectrolyte-dilute solvent phase. For many of the applications seeking to exploit coacervation, characterization of the interface between the solvent phase and the coacervate is of paramount importance. In this talk, we will present the results of field-theoretic simulations for a coarse-grained polyelectrolyte model that exhibits complex coacervation. Our simulations sample the fully-fluctuating fields in three-dimensions and provide a detailed characterization of the interface between the solvent and the coacervate phase for symmetric polyelectrolytes (where both the polycations and the polyanions carry identical charge densities) as a function of salt concentration and strength of the electrostatic fields. Finally, we characterize the interfacial properties for a select set of asymmetric conditions.

  4. Tuning the properties of conjugated polyelectrolytes and application in a biosensor platform

    Science.gov (United States)

    Chen, Liaohai

    2004-05-18

    The present invention provides a method of detecting a biological agent including contacting a sample with a sensor including a polymer system capable of having an alterable measurable property from the group of luminescence, anisotropy, redox potential and uv/vis absorption, the polymer system including an ionic conjugated polymer and an electronically inert polyelectrolyte having a biological agent recognition element bound thereto, the electronically inert polyelectrolyte adapted for undergoing a conformational structural change upon exposure to a biological agent having affinity for binding to the recognition element bound to the electronically inert polyelectrolyte, and, detecting the detectable change in the alterable measurable property. A chemical moiety being the reaction product of (i) a polyelectrolyte monomer and (ii) a biological agent recognition element-substituted polyelectrolyte monomer is also provided.

  5. Colloid stabilization by polyelectrolytes. Application to decontamination processes of nuclear reactors

    International Nuclear Information System (INIS)

    Sodium salts of the following anionic polyelectrolytes were evaluated as particle stabilizers: polyacrylic acid, polymethacrylic acid, poly (methyl vinyl ether/maleic anhydride), sulfonated polymers. A cationic polyelectrolyte, a polyamine, was also evaluated. An active and an inactive oxidized carbon steel sample were treated in the same experimental set-up with the decontaminating reagent and with or without the polyelectrolyte. Activity pick-up by the inactive sample was measured. When no polyelectrolyte was added, 15% of the Co-60 activity was redeposited. With polyelectrolyte addition in the 5-450 mg kg-1 range, the Co60 activity redeposition ranged from 8.5 down to 0.8%. Polyacrylic acid was the most effective reagent. The transfer of the magnetite outer oxide crystals from the active to the inactive surfaces was identified on SEM micrographs. (author)

  6. Temperature-induced changes in polyelectrolyte films at the solid-liquid interface

    CERN Document Server

    Steitz, R; Tauer, K; Khrenov, Yu V; Klitzing, K V

    2002-01-01

    Polyelectrolyte multilayers (film thickness 30-60 nm) were built on top of silicon substrates by layer-by-layer deposition of oppositely charged polyelectrolytes from aqueous solutions. Three kinds of films were investigated: (A) films of a homo-polyelectrolyte and a diblock copolymer with a thermosensitive poly(N-isopropyl-acrylamide) block and (B) and (C) two reference systems built solely from homo-polyelectrolytes of opposite charges. Thermal behavior and subsequent structural changes of the functionalized films against D sub 2 O were investigated by neutron reflectometry. All films showed irreversible annealing effects upon heating. In addition, the thermosensitive films showed a decrease in thickness at elevated temperature (>30 C) while the reference samples, composed of thermo-insensitive polyelectrolytes only, did not. (orig.)

  7. Synthesis and Reactivity of Tripodal Complexes Containing Pendant Bases

    Energy Technology Data Exchange (ETDEWEB)

    Blacquiere, Johanna M.; Pegis, Michael L.; Raugei, Simone; Kaminsky, Werner; Forget, Amelie; Cook, Sarah; Taguchi, Taketo; Borovik, Andrew S.; Mayer, James M.

    2014-09-02

    The synthesis of a new tripodal ligand family is reported, with tertiary-amine groups in the second-coordination sphere. The ligands are tris(amido)amine derivatives, with the pendant amines attached via a peptide coupling strategy. They were designed to be used in new catalysts for the oxygen reduction reaction (ORR), in which the pendant acid/base group could improve catalyst performance. Two members of the new ligand family were each metallated with Co(II) and Zn(II) to afford trigonal monopyramidal complexes. Reaction of the cobalt complexes, [Co(L)]-, with dioxygen reversibly generates a small amount of a Co(III)-superoxo species, which was characterized by EPR. Protonation of the zinc complex Zn[N{CH2CH2NC(O)CH2N(CH2Ph)2}3)-– ([Zn(TNBn)]-) with one equivalent of acid occurs with displacement and dissociation of an amide ligand. Addition of excess acid to the any of the complexes [M(L)]- results in complete proteolysis and formation of the ligands H3L. This decomposition limits the use of these complexes as catalysts for the ORR. An alternative ligand with two pyridyl arms was also prepared but could not be metallated. These studies highlight the importance of stability of the primary-coordination sphere of ORR electrocatalysts to both oxidative and acidic conditions. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  8. A Knowledge base model for complex forging die machining

    CERN Document Server

    Mawussi, Kwamiwi; 10.1016/j.cie.2011.02.016

    2011-01-01

    Recent evolutions on forging process induce more complex shape on forging die. These evolutions, combined with High Speed Machining (HSM) process of forging die lead to important increase in time for machining preparation. In this context, an original approach for generating machining process based on machining knowledge is proposed in this paper. The core of this approach is to decompose a CAD model of complex forging die in geometric features. Technological data and topological relations are aggregated to a geometric feature in order to create machining features. Technological data, such as material, surface roughness and form tolerance are defined during forging process and dies design. These data are used to choose cutting tools and machining strategies. Topological relations define relative positions between the surfaces of the die CAD model. After machining features identification cutting tools and machining strategies currently used in HSM of forging die, are associated to them in order to generate mac...

  9. Complexation study of cadmium with a schiff base vanillin trisbuffer

    International Nuclear Information System (INIS)

    Polarographic study of complexation of cadmium with a Schiff base derived from vanillin and trisbuffer was carried out in DMF-water media of three different compositions (viz. 0%, 30% and 50% v/v of DMF). 1:1, 1:2 and 1:3 complex species are present in the solution. Overall stability constants were calculated using DeFord and Hume treatment at three different temperatures (viz. 300, 400 and 500). Free energy change ΔG, enthalpy change ΔH and entropy change ΔS were also calculated for all the three media. A new, methamatical model, recently developed by Mihailov, to calculate stability constants from nbar values was used to check the data obtained from DeFord and Hume method. (author)

  10. Efficient target control of complex networks based on preferential matching

    CERN Document Server

    Zhang, Xizhe; Lv, Tianyang

    2016-01-01

    Controlling a complex network towards a desire state is of great importance in many applications. Existing works present an approximate algorithm to find the driver nodes used to control partial nodes of the network. However, the driver nodes obtained by this algorithm depend on the matching order of nodes and cannot get the optimum results. Here we present a novel algorithm to find the driver nodes for target control based on preferential matching. The algorithm elaborately arrange the matching order of nodes in order to minimize the size of the driver nodes set. The results on both synthetic and real networks indicate that the performance of proposed algorithm are better than the previous one. The algorithm may have various application in controlling complex networks.

  11. Langmuir-Blodgett Films from Schiff Base Aluminium ( Ⅲ ) Complex

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The characteristics of the LB films of Schiff base aluminium( Ⅲ ), tris(2-hydroxy-5-nitro N-dodecyl-benzylideneaminato) aluminium ( Ⅲ ) [Al (TA 12) 3], were studied. The surface pres sure-area(r-A) isotherm of Al(TA12)3 in the pure water subphase was investigated. The molec ular area, 0.48 nm2, is one-third of the expected value that indicates the formation of an aggre gate. The Langmuir-Blodgett (LB) films of Al(TA12) 3 were transferred and characterized. The UV-Vis spectra and the AFM image both confirmed that the J-aggregates formed. The polarized UV-Vis spectra indicated that the complex plane had to be oriented with an angle of about 30° to the substrate surface. The IR spectra suggested that the complexation took place between aluminium ions and the oxygen atoms of the ligand rather than the nitrogen atom.

  12. Design of ANSYS-based Cathode with Complex Groove

    Institute of Scientific and Technical Information of China (English)

    范植坚; 赵刚刚; 张丽娟

    2012-01-01

    The profile of cathode with complex groove needs to be modified time after time during design of electrochemical machining (ECM) cathode.A design scheme using finite element method (FEM) for cathode with complex profile is put forward to shorten the period of cathode design.Based on Laplace equation,the potential distribution on parameter-transformation model was calculated by using ANSYS,which is compared to the potential distribution calculated by substituting conductivity and current efficiency into Laplace equation.According to the difference between the results calculated and simulated by ANSYS,the cathode profile was modified by adjusting the cathode boundary.The experiments show that the dimensions and shape of workpiece machined by numerically simulated cathode conform well with the blueprint.

  13. H.264 SVC Complexity Reduction Based on Likelihood Mode Decision

    Directory of Open Access Journals (Sweden)

    L. Balaji

    2015-01-01

    Full Text Available H.264 Advanced Video Coding (AVC was prolonged to Scalable Video Coding (SVC. SVC executes in different electronics gadgets such as personal computer, HDTV, SDTV, IPTV, and full-HDTV in which user demands various scaling of the same content. The various scaling is resolution, frame rate, quality, heterogeneous networks, bandwidth, and so forth. Scaling consumes more encoding time and computational complexity during mode selection. In this paper, to reduce encoding time and computational complexity, a fast mode decision algorithm based on likelihood mode decision (LMD is proposed. LMD is evaluated in both temporal and spatial scaling. From the results, we conclude that LMD performs well, when compared to the previous fast mode decision algorithms. The comparison parameters are time, PSNR, and bit rate. LMD achieve time saving of 66.65% with 0.05% detriment in PSNR and 0.17% increment in bit rate compared with the full search method.

  14. Combined voltammetric and spectroscopic investigation of binding interaction between nifedipine and human serum albumin on polyelectrolyte modified ITO electrode

    International Nuclear Information System (INIS)

    Highlights: • The polyelectrolyte coated ITO surface was used as working electrode. • HSA was bounded onto modified electrode surface. • The interaction of nifedipine with HSA was studied. • Electrochemical and fluorescence techniques were used for characterization. -- Abstract: The binding interaction between the drug molecule, nifedipine (Nf), and the human serum albumin (HSA) on polyelectrolyte modified indium tin oxide (ITO) electrode has been investigated by the combination of electrochemical and fluorescence spectroscopy techniques. Surface modification has also been characterized by scanning electron microscopy (SEM) and Contact Angle (CA) measurements in each step. The cyclic voltammetry, electrochemical impedance parameters (peak potential difference (ΔEp)), peak current difference (ΔIp) and charge-transfer resistance (Rct) indicate that nifedipine strongly interacted with human serum albumin molecule on the polyelectrolyte modified ITO electrode surface. Stern–Volmer quenching constant Ka is inversely correlated with the temperature, which indicates that the probable quenching mechanism of the nifedipine-human serum albumin binding reaction is initiated by complex formation. The results obtained from these techniques showed that Nf could bind to HSA. The binding constant (Kb) and the number of binding sites (n) of the drug with HSA at different temperatures were determined. At 298 K, Kb was found as 4.04 × 10−3 and n was 1.08 for Nf-HSA. According to the van’t Hoff equation, the thermodynamic parameters, ΔG, ΔH and ΔS, were obtained, showing the involvement of hydrophobic and electrostatic force in this interaction

  15. Increased complexity of gene structure and base composition in vertebrates

    Institute of Scientific and Technical Information of China (English)

    Ying Wu; Huizhong Yuan; Shengjun Tan; Jian-Qun Chen; Dacheng Tian; Haiwang Yang

    2011-01-01

    How the structure and base composition of genes changed with the evolution of vertebrates remains a puzzling question. Here we analyzed 895 orthologous protein-coding genes in six multicellular animals: human, chicken, zebrafish, sea squirt, fruit fly, and worm. Our analyses reveal that many gene regions, particularly intron and 3' UTR, gradually expanded throughout the evolution of vertebrates from their invertebrate ancestors, and that the number of exons per gene increased. Studies based on all protein-coding genes in each genome provide consistent results.We also find that GC-content increased in many gene regions (especially 5' UTR) in the evolution of endotherms, except in coding-exons.Analysis of individual genomes shows that 3′ UTR demonstrated stronger length and CC-content correlation with intron than 5' UTR, and gene with large intron in all six species demonstrated relatively similar GC-content. Our data indicates a great increase in complexity in vertebrate genes and we propose that the requirement for morphological and functional changes is probably the driving force behind the evolution of structure and base composition complexity in multicellular animal genes.

  16. Airworthiness Compliance Verification Method Based on Simulation of Complex System

    Institute of Scientific and Technical Information of China (English)

    XU Haojun; LIU Dongliang; XUE Yuan; ZHOU Li; MIN Guilong

    2012-01-01

    A study is conducted on a new airworthiness compliance verification method based on pilot-aircraft-environment complex system simulation.Verification scenarios are established by “block diagram” method based on airworthiness criteria..A pilot-aircraft-environment complex model is set up and a virtual flight testing method based on connection of MATLAB/Simulink and Flightgear is proposed.Special researches are conducted on the modeling of pilot manipulation stochastic parameters and manipulation in critical situation.Unfavorable flight factors of certain scenario are analyzed,and reliability modeling of important system is researched.A distribution function of small probability event and the theory on risk probability measurement are studied.Nonlinear function is used to depict the relationship between the cumulative probability and the extremum of the critical parameter.A synthetic evaluation model is set up,modified genetic algorithm (MGA) is applied to ascertaining the distribution parameter in the model,and amore reasonable result is obtained.A clause about vehicle control functions (VCFs) verification in MIL-HDBK-516B is selected as an example to validate the practicability of the method.

  17. Electrically driven ion separations and nanofiltration through membranes coated with polyelectrolyte multilayers

    Science.gov (United States)

    White, Nicholas

    Polyelectrolyte multilayer (PEM) films deposited using the layer-by-layer (LBL) method are attractive for their simple deposition, tailorable nature, scalability, and charge or size-based selectivity for solutes. This dissertation explores ion separations in electrodialysis (ED) and solute removal through nanofiltration with PEMs deposited on polymer membranes. ED membranes typically exhibit modest selectivities between monovalent and divalent ions. In contrast, this work shows that K+/Mg 2+ ED selectivities reach values >1000 when using Nafion 115 cation-exchange membranes coated with multilayer poly(4-styrenesulfonate) (PSS)/protonated poly(allylamine) (PAH) films. For comparison, the corresponding K+ /Mg2+ selectivity of bare Nafion 115 is 20,000, presumably because the applied current is below the limiting value for K+ and H+ transport is negligible at this high K+ concentration. The high selectivities of these membranes may enable electrodialysis applications such as purification of salts that contain divalent or trivalent ions. The high ED selectivities of (PAH/PSS)5PAH-coated Nafion membranes translate to separations with Li+/Co2+ and K +/La3+. Even with adsorption of only 3 polyelectrolyte layers, Nafion membranes exhibit a Li+/Co2+ selectivity >23. However, the resistance to monovalent-ion passage does not decrease significantly with fewer polyelectrolyte layers. At overlimiting currents, hydroxides from water splitting form insoluble metal hydroxides to foul the membrane. With 0.1 M source-phase salt concentrations, transference numbers for monovalent cations approach unity and selectivities are >5000 because the diffusion-limited K+ or Li+ currents exceed the applied current. However, ED selectivities gradually decline with time. Thus, future research should aim to increase membrane stability and limiting currents to fully exploit the remarkable selectivity of these membranes. PEMs deposited on commercial ultrafiltration (UF) membranes also show high

  18. p-cymene based ruthenium complexes as catalysts

    OpenAIRE

    Fonseca, Joel David Avelino

    2011-01-01

    Tese de mestrado em Química Tecnológica (Química Tecnológica e Qualidade), apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2011 p-Cymene based ruthenium complexes were employed in the alkylation of tbutylamine with phenethyl alcohol by redox neutral alkylation and in the reduction of acetophenone and benzaldehyde by transfer hydrogenation. A range of in situ generated catalysts formed by [RuX2(p-cymene)]2 dimers (X=Cl or I) with dppf, DPEPhos, dippf or P(i- Bu)3 and...

  19. Intelligent Transportation Control based on Proactive Complex Event Processing

    Directory of Open Access Journals (Sweden)

    Wang Yongheng

    2016-01-01

    Full Text Available Complex Event Processing (CEP has become the key part of Internet of Things (IoT. Proactive CEP can predict future system states and execute some actions to avoid unwanted states which brings new hope to intelligent transportation control. In this paper, we propose a proactive CEP architecture and method for intelligent transportation control. Based on basic CEP technology and predictive analytic technology, a networked distributed Markov decision processes model with predicting states is proposed as sequential decision model. A Q-learning method is proposed for this model. The experimental evaluations show that this method works well when used to control congestion in in intelligent transportation systems.

  20. Smart electronic yarns and wearable fabrics for human biomonitoring made by carbon nanotube coating with polyelectrolytes.

    Science.gov (United States)

    Shim, Bong Sup; Chen, Wei; Doty, Chris; Xu, Chuanlai; Kotov, Nicholas A

    2008-12-01

    The idea of electronic yarns and textiles has appeared for quite some time, but their properties often do not meet practical expectations. In addition to chemicallmechanical durability and high electrical conductivity, important materials qualifications include weavablity, wearability, light weight, and "smart" functionalities. Here we demonstrate a simple process of transforming general commodity cotton threads into intelligent e-textiles using a polyelectrolyte-based coating with carbon nanotubes (CNTs). Efficient charge transport through the network of nanotubes (20 omega/cm) and the possibility to engineer tunneling junctions make them promising materials for many high-knowledge-content garments. Along with integrated humidity sensing, we demonstrate that CNT-cotton threads can be used to detect albumin, the key protein of blood, with high sensitivity and selectivity. Notwithstanding future challenges, these proof-of-concept demonstrations provide a direct pathway for the application of these materials as wearable biomonitoring and telemedicine sensors, which are simple, sensitive, selective, and versatile. PMID:19367926

  1. Self-consistent field theory of adsorption of flexible polyelectrolytes onto an oppositely charged sphere

    International Nuclear Information System (INIS)

    The adsorption of flexible polyelectrolyte (PE) with the smeared charge distribution onto an oppositely charged sphere immersed in a PE solution is studied numerically with the continuum self-consistent field theory. The power law scaling relationships between the boundary layer thickness and the surface charge density and the charge fraction of PE chains revealed in the study are in good agreement with the existing analytical result. The curvature effect on the degree of charge compensation of the total amount of charges on the adsorbed PE chains over the surface charges is examined, and a clear understanding of it based on the dependences of the degree of charge compensation on the surface charge density and the charge fraction of PE chains is established

  2. Visualization of Complex Networks Based on Dyadic Curvelet Transform

    Directory of Open Access Journals (Sweden)

    Kaoru Hirota

    2006-07-01

    Full Text Available A visualization method is proposed for understanding the structure of complex networks based on an extended Curvelet transform named Dyadic Curvelet Transform (DClet. The proposed visualization method comes to answer specific questions about structures of complex networks by mapping data into orthogonal localized events with a directional component via the Cartesian sampling sets of detail coefficients. It behaves in the same matter as human visual system, seeing in terms of segments and distinguishing them by scale and orientation. Compressing the network is another fact. The performance of the proposed method is evaluated by two different networks with structural properties of small world networks with N = 16 vertices, and a globally coupled network with size N = 1024 and 523 776 edges. As the most large scale real networks are not fully connected, it is tested on the telecommunication network of Iran as a real extremely complex network with 92 intercity switching vertices, 706 350 E1 traffic channels and 315 525 transmission channels. It is shown that the proposed method performs as a simulation tool for successfully design of network and establishing the necessary group sizes. It can clue the network designer in on all structural properties that network has.

  3. Conformational thermodynamics of biomolecular complexes: The histogram-based method

    Science.gov (United States)

    Das, Amit; Sikdar, Samapan; Ghosh, Mahua; Chakrabarti, J.

    2015-09-01

    Conformational changes in biomacromolecules govern majority of biological processes. Complete characterization of conformational contributions to thermodynamics of complexation of biomacromolecules has been challenging. Although, advances in NMR relaxation experiments and several computational studies have revealed important aspects of conformational entropy changes, efficient and large-scale estimations still remain an intriguing facet. Recent histogram-based method (HBM) offers a simple yet rigorous route to estimate both conformational entropy and free energy changes from same set of histograms in an efficient manner. The HBM utilizes the power of histograms which can be generated as accurately as desired from an arbitrarily large sample space from atomistic simulation trajectories. Here we discuss some recent applications of the HBM, using dihedral angles of amino acid residues as conformational variables, which provide good measure of conformational thermodynamics of several protein-peptide complexes, obtained from NMR, metal-ion binding to an important metalloprotein, interfacial changes in protein-protein complex and insight to protein function, coupled with conformational changes. We conclude the paper with a few future directions worth pursuing.

  4. Nanocapsules templated on liquid cores stabilized by graft amphiphilic polyelectrolytes

    Science.gov (United States)

    Szafraniec, Joanna; Janik, Małgorzata; Odrobińska, Joanna; Zapotoczny, Szczepan

    2015-03-01

    A surfactant-free method of preparation of nanocapsules templated on liquid cores using amphiphilic graft polyelectrolytes was developed. A model photoactive copolymer, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate) with grafted poly(vinylnaphthalene) chains (PAMPS-graft-PVN) was used to stabilize toluene droplets in an aqueous emulsion. The macromolecules, due to their amphiphilic character and the presence of strong ionic groups, tend to undergo intramolecular aggregation in water but at the water-oil interface less compact conformation is preferred with PVN grafts anchoring in the oil phase and the charged PAMPS main chains residing in the aqueous phase, thus stabilizing the nanoemulsion droplets. Formation of such nanocapsules was confirmed by dynamic light scattering measurements as well as SEM and cryo-TEM imaging. Grafting density and content of the chromophores in the graft copolymers were varied in order to achieve high stability of the coated nanodroplets. It was shown that the capsules are better stabilized by the copolymers with many short hydrophobic grafts than with fewer but longer ones. Use of photoactive polyelectrolytes enabled spectroscopic investigation of the relationship between conformation of the macromolecules and stabilization of the oil-core nanocapsules. Long-term stability of the nanocapsules was achieved and further increased by multilayer shell formation using polyelectrolytes deposited via the layer-by-layer approach. The obtained capsules served as efficient nanocontainers for a hydrophobic fluorescent probe. The proposed strategy of nanocapsule preparation may be easily extended to biologically relevant polymers and applied to fabricate liquid core nanodelivery systems without the need of using low molecular weight additives which may have adverse effects in numerous biomedical applications.A surfactant-free method of preparation of nanocapsules templated on liquid cores using amphiphilic graft polyelectrolytes was developed

  5. Polyelectrolyte-mediated bridging interactions: columnar macromolecular phases

    Energy Technology Data Exchange (ETDEWEB)

    Licer, Matjaz [Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, SI-1000 Ljubljana (Slovenia); Podgornik, Rudolf [Department of Physics, Faculty of Mathematics and Physics, and Institute of Biophysics, School of Medicine, University of Ljubljana, SI-1000 Ljubljana (Slovenia)

    2010-10-20

    We present a mean-field theory for charged polymer chains in an external electrostatic field in the weak and strong coupling limits. We apply the theory to describe the statistical mechanics of flexible polyelectrolyte chains in a hexagonal columnar lattice of stiff cylindrical macroions, such as DNA, in a bathing solution of a uni-univalent salt (e.g. NaCl). The salt effects are first described in the Debye-Hueckel framework. This yields the macroion electrostatic field in the screened Coulomb form, which we take to represent the mean field into which the chains are immersed. We introduce the Green's function for the polyelectrolyte chains and derive the corresponding Edwards equation which we solve numerically in the Wigner-Seitz cylindrical cell using the ground state dominance ansatz. The solutions indicate the presence of polyelectrolyte bridging, which results in a like-charge attraction between stiff macroions. Then we reformulate the Edwards theory for the strong coupling case and use the standard Poisson-Boltzmann picture to describe the salt solution. We begin with the free energy which we minimize to obtain the Euler-Lagrange equations. The solutions yield self-consistently determined monomer density and electrostatic fields. We furthermore calculate the free energy density as well as the total osmotic pressure in the system. We again show that bridging implicates like-charge attractions of entropic origin between stiff cylindrical macroions. By analyzing the osmotic pressure we demonstrate that, in certain parts of the parameter space, a phase transition occurs between two phases of the same hexagonal symmetry.

  6. SVD-based digital image watermarking using complex wavelet transform

    Indian Academy of Sciences (India)

    A Mansouri; A Mahmoudi Aznaveh; F Torkamani Azar

    2009-06-01

    A new robust method of non-blind image watermarking is proposed in this paper. The suggested method is performed by modification on singular value decomposition (SVD) of images in Complex Wavelet Transform (CWT) domain while CWT provides higher capacity than the real wavelet domain. Modification of the appropriate sub-bands leads to a watermarking scheme which favourably preserves the quality. The additional advantage of the proposed technique is its robustness against the most of common attacks. Analysis and experimental results show much improved performance of the proposed method in comparison with the pure SVD-based as well as hybrid methods (e.g. DWT-SVD as the recent best SVD-based scheme).

  7. Tailor-made polyelectrolyte microcapsules: from multilayers to smart containers.

    Science.gov (United States)

    Peyratout, Claire S; Dähne, Lars

    2004-07-19

    This review addresses the fabrication and properties of novel polyelectrolyte microcapsules, with an emphasis on their mechanical and permeability properties. Ease of preparation through layer-by-layer self assembly, accurate control over wall thickness as well as flexibility in the choice of constituents make these capsules very promising for numerous applications in materials and life science. Moreover, by engineering the inner and outer interfaces, these capsules can be used as microreactors for precipitation, crystallization, and polymerization reactions, as well as enzymatic, and heterogeneous catalysis.

  8. Functionalized Conjugated Polyelectrolytes for Biological Sensing and Imaging.

    Science.gov (United States)

    Zhan, Ruoyu; Liu, Bin

    2016-06-01

    Conjugated polyelectrolytes (CPEs) are macromolecules with highly delocalized π-conjugated backbones and charged side chains, which are unique types of active materials, with wide applications in optoelectronics, sensing, imaging, and therapy. By attaching specific groups (e.g., recognition elements, magnetic resonance (MR) contrast agents, gene carriers, and drugs) to the side chain or backbone of CPEs, functionalized CPEs have been developed and used for specific biological applications. In this account, we summarize the recent progress of functionalized CPEs with respect to their synthesis and biomedical applications. Future perspectives are also discussed at the end. PMID:27230631

  9. Importance of Varying Permittivity on the Conductivity of Polyelectrolyte Solutions

    Science.gov (United States)

    Fahrenberger, Florian; Hickey, Owen A.; Smiatek, Jens; Holm, Christian

    2015-09-01

    Dissolved ions can alter the local permittivity of water; nevertheless most theories and simulations ignore this fact. We present a novel algorithm for treating spatial and temporal variations in the permittivity and use it to measure the equivalent conductivity of a salt-free polyelectrolyte solution. Our new approach quantitatively reproduces experimental results unlike simulations with a constant permittivity that even qualitatively fail to describe the data. We can relate this success to a change in the ion distribution close to the polymer due to the buildup of a permittivity gradient.

  10. Advantage of Fluorescence Correlation Spectroscopy for the Study of Polyelectrolytes

    Institute of Scientific and Technical Information of China (English)

    贾鹏翔; 宫永宽; 王生勤; 赵江

    2012-01-01

    The advantage of fluorescence correlation spectroscopy to study single chain behavior of polyelectrolytes has been demonstrated by checking the coil-to-globule transition ofpoly 2-vinylpyridine with the change ofpH value in aqueous solution. The ultra-high sensitivity of FCS allows measurement at extreme dilution where the effect of electrostatic interaction between the chains is greatly suppressed. The results exposed first-order conformation tran- sition of P2VP as detected by FCS while inter-chain aggregation occurred in the experiments of dynamic light scat- tering.

  11. Electrochemical analysis of metal complexes.

    OpenAIRE

    Jong, de, J.

    1987-01-01

    The present study is concerned with the electroanalytical chemistry of complexes of metals with large ligands. The main purpose was to develop quantitative descriptions of the voltammetric current-potential relation of metal complex systems with different diffusion coefficients of the species involved and of the conductometric response of metal/polyelectrolyte systems at various metal-to-ligand ratios. A further goal was to illustrate the theoretical treatments with some experiments on model ...

  12. Complexity

    CERN Document Server

    Gershenson, Carlos

    2011-01-01

    The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.

  13. Influence of higher valent ions on flexible polyelectrolyte stiffness and counter-ion distribution.

    Science.gov (United States)

    Chremos, Alexandros; Douglas, Jack F

    2016-04-28

    We investigate the influence of counter-ion valency on the flexibility of highly charged flexible polymer chains using molecular dynamics simulations that include both salt and an explicit solvent. As observed experimentally, we find that divalent counter-ions greatly reduce the chain persistence length, lp, in comparison with monovalent counter-ions. On the other hand, polyelectrolyte chains having trivalent counter-ions adopt a much more compact conformation than polyelectrolytes having monovalent and divalent counter-ions. We demonstrate that the tendency of polyelectrolyte chains to become deformed by proximal high valence counter-ions is due to chain "coiling" around the counter-ions. In particular, we find that the number of contacts that the proximal counter-ions have with the polyelectrolyte dictates the extent of chain coiling. This ion-binding induced coiling mechanism influences not only the conformational properties of the polyelectrolyte, but also the counter-ion distribution around the chain. Specifically, we find that higher valent counter-ions lead both to a counter-ion enrichment in close proximity to the polyelectrolyte and to a significant reduction in the spatial extent of the diffuse counter-ion cloud around the polyelectrolyte.

  14. Influence of higher valent ions on flexible polyelectrolyte stiffness and counter-ion distribution

    Science.gov (United States)

    Chremos, Alexandros; Douglas, Jack F.

    2016-04-01

    We investigate the influence of counter-ion valency on the flexibility of highly charged flexible polymer chains using molecular dynamics simulations that include both salt and an explicit solvent. As observed experimentally, we find that divalent counter-ions greatly reduce the chain persistence length, lp, in comparison with monovalent counter-ions. On the other hand, polyelectrolyte chains having trivalent counter-ions adopt a much more compact conformation than polyelectrolytes having monovalent and divalent counter-ions. We demonstrate that the tendency of polyelectrolyte chains to become deformed by proximal high valence counter-ions is due to chain "coiling" around the counter-ions. In particular, we find that the number of contacts that the proximal counter-ions have with the polyelectrolyte dictates the extent of chain coiling. This ion-binding induced coiling mechanism influences not only the conformational properties of the polyelectrolyte, but also the counter-ion distribution around the chain. Specifically, we find that higher valent counter-ions lead both to a counter-ion enrichment in close proximity to the polyelectrolyte and to a significant reduction in the spatial extent of the diffuse counter-ion cloud around the polyelectrolyte.

  15. The processing of polyelectrolyte-covered magnetite nanoparticles in the form of nanostructured thin films

    Energy Technology Data Exchange (ETDEWEB)

    Marangoni, Valeria S. [Universidade de Sao Paulo, Instituto de Fisica de Sao Carlos (Brazil); Martins, Marccus Victor A.; Souza, Jose A. [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas (Brazil); Oliveira, Osvaldo N.; Zucolotto, Valtencir [Universidade de Sao Paulo, Instituto de Fisica de Sao Carlos (Brazil); Crespilho, Frank N., E-mail: frankcrespilho@gmail.com [Instituto de Quimica de Sao Carlos, CP 780, Universidade de Sao Paulo (Brazil)

    2012-03-15

    Magnetic nanoparticles are promising for a variety of applications, such as biomedical devices, spin electronics, magnetic data storage media, to name a few. However, these goals may only be reached if stable and organized structures are fabricated. In this article, we report on a single-step synthetic route with the coprecipitation method, in which iron oxide magnetic nanoparticles (Fe{sub 3}O{sub 4} NPs) were stabilized in aqueous media using the poly(diallyldimethylammonium chloride) (PDAC) polyelectrolyte. The Fe{sub 3}O{sub 4} NPs had a diameter of ca. 5 nm, according to transmission electron microscopy (TEM) images, being arranged in an inverse spinel structure typical of magnetite. An investigation with infrared spectroscopy indicated that the mechanisms of stabilization in the polymer matrix were based on the interaction between quaternary amide groups from PDAC and the nanoparticle surface. The Fe{sub 3}O{sub 4}-PDAC NPs exhibited considerable magnetic susceptibility, with a monotonic increase in the magnetization with decreasing temperature. These Fe{sub 3}O{sub 4}-PDAC NPs were immobilized in layer-by-layer (LbL) films, being alternated with layers of poly(vinylsulfonic acid) (PVS). The LbL films were much rougher than typical films made with polyelectrolytes, and Fe{sub 3}O{sub 4}-PDAC NPs have been responsible for the high electrocatalytic activity toward H{sub 2}O{sub 2} reduction, with an overpotential shift of 0.69 V. Overall, the stability, magnetic properties and film-forming ability indicate that the Fe{sub 3}O{sub 4}-PDAC NPs may be used for nanoelectronics and bioelectrochemical devices requiring reversible and magnetic redox materials.

  16. Potential Use of Polyelectrolyte Multilayer thin Films in Vascular Tissue Engineering:Evaluation of the Viability and Adhesion of Endothelial Cells

    Institute of Scientific and Technical Information of China (English)

    Cédric; BOURA; Halima; KERDJOUDJ; Vanessa; MOBY; Pierre; SCHAAJ; Jean; Claude; VOEGEL; Jean-Franois; STOLTZ; Patrick; MENU

    2005-01-01

    1 IntroductionA method in vascular tissue engineering to obtain hemocompatible synthetic prosthesis consists to cover the luminal surface by a monolayer of endothelial cells (ECs). Nevertheless, the surface of current prosthesis does not favour the development of an ECs monolayer. Recently, a new versatile method of self-assembled architectures based on the alternate adsorption of polycations and polyanions has been developed to lead to the build-up of multilayered polyelectrolyte films (MPF). This new type...

  17. Condensation of nonstochiometric DNA/polycation complexes by divalent cations.

    Science.gov (United States)

    Budker, Vladimir; Trubetskoy, Vladimir; Wolff, Jon A

    2006-12-15

    This study found that divalent cations induced the further condensation of partially condensed DNA within nonstochiometric polycation complexes. The addition of a few mmol of a divalent cation such as calcium reduced by half the inflection point at which DNA became fully condensed by poly-L-lysine (PLL) and a variety of other polycations. The effect on DNA condensation was initially observed using a new method, which is based on the concentration-dependent self-quenching of fluorescent moieties (e.g., rhodamine) covalently linked to the DNA backbone at relatively high densities. Additional analyses, which employed ultracentrifugation, dynamic light scattering, agarose gel electrophoresis, and atomic force microscopy, confirmed the effect of divalent cations. These results provide an additional accounting of the process by which divalent cations induce greater chromatin compaction that is based on the representation of chromatin fibers as a nonstoichiometric polyelectrolyte complex. They also offer a new approach to assemble nonviral vectors for gene therapy.

  18. ON THE COMPLEXITY OF THE NORMAL BASES VIA PRIME GAUSS PERIOD OVER FINITE FIELDS

    Institute of Scientific and Technical Information of China (English)

    Qunying LIAO; Keqin FENG

    2009-01-01

    A formula on the complexity of the normal bases generated by prime Gauss period over finite fields is presented in terms of cyclotomic numbers. Then, the authors determine explicitly the complexity of such normal bases and their dual bases in several cases where the related cyclotomic numbers have been calculated. Particularly, the authors find several series of such normal bases with low complexity.

  19. Impact of thermal annealing on wettability and antifouling characteristics of alginate poly-l-lysine polyelectrolyte multilayer films.

    Science.gov (United States)

    Diamanti, Eleftheria; Muzzio, Nicolas; Gregurec, Danijela; Irigoyen, Joseba; Pasquale, Miguel; Azzaroni, Omar; Brinkmann, Martin; Moya, Sergio Enrique

    2016-09-01

    Polyelectrolyte multilayers (PEMs) of poly-l-lysine (PLL) and alginic acid sodium salt (Alg) are fabricated applying the layer by layer technique and annealed at a constant temperature; 37, 50 and 80°C, for 72h. Atomic force microscopy reveals changes in the topography of the PEM, which is changing from a fibrillar to a smooth surface. Advancing contact angle in water varies from 36° before annealing to 93°, 77° and 95° after annealing at 37, 50 and 80°C, respectively. Surface energy changes after annealing were calculated from contact angle measurements performed with organic solvents. Quartz crystal microbalance with dissipation, contact angle and fluorescence spectroscopy measurements show a significant decrease in the adsorption of the bovine serum albumin protein to the PEMs after annealing. Changes in the physical properties of the PEMs are interpreted as a result of the reorganization of the polyelectrolytes in the PEMs from a layered structure into complexes where the interaction of polycations and polyanions is enhanced. This work proposes a simple method to endow bio-PEMs with antifouling characteristics and tune their wettability. PMID:27209385

  20. Removal and recovery of furfural, 5-hydroxymethylfurfural, and acetic acid from aqueous solutions using a soluble polyelectrolyte.

    Science.gov (United States)

    Carter, Brian; Gilcrease, Patrick C; Menkhaus, Todd J

    2011-09-01

    In the cellulosic ethanol process, furfural, 5-hydroxymethylfurfural (HMF), and acetic acid are formed during the high temperature acidic pretreatment step needed to convert biomass into fermentable sugars. These compounds can inhibit cellulase enzymes and fermentation organisms at relatively low concentrations (≥ 1 g/L). Effective removal of these inhibitory compounds would allow the use of more severe pretreatment conditions to improve sugar yields and lead to more efficient fermentations; if recovered and purified, they could also be sold as valuable by-products. This study investigated the separation of aldhehydes (furfural and HMF) and organic acid (acetic acid) inhibitory compounds from simple aqueous solutions by using polyethyleneimene (PEI), a soluble cationic polyelectrolyte. PEI added to simple solutions of each inhibitor at a ratio of 1 mol of functional group to 1 mol inhibitor removed up to 89.1, 58.6, and 81.5 wt% of acetic acid, HMF, and furfural, respectively. Furfural and HMF were recovered after removal by washing the polyelectrolyte/inhibitor complex with dilute sulfuric acid solution. Recoveries up to 81.0 and 97.0 wt% were achieved for furfural and HMF, respectively. The interaction between PEI and acetic acid was easily disrupted by the addition of chloride ions, sulfate ions, or hydroxide ions. The use of soluble polymers for the removal and recovery of inhibitory compounds from biomass slurries is a promising approach to enhance the efficiency and economics of an envisioned biorefinery. PMID:21455937