WorldWideScience

Sample records for anchored amphiphilic polymers

  1. Immobilization of lipid vesicles on polymer support via an amphiphilic peptidic anchor: application to a membrane enzyme.

    Science.gov (United States)

    Percot, A; Zhu, X X; Lafleur, M

    2000-01-01

    To immobilize lipid vesicles on a polymer support, we have used a peptidic anchor with the following sequence: Ala-Ala-Leu-Leu-Leu-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-A la-Ala-Ala-Ala-Ala-Ala-Ala-Trp-Lys-Lys-Lys-Lys-Lys-Lys. This amphiphilic peptide was previously designed in our group to interact spontaneously and strongly with vesicles without perturbing their permeability. At the end of the solid-phase peptide synthesis, the peptide was left on the polymer beads and this novel polymer-peptide system was used for vesicle immobilization. It was shown that this polymer-peptide system could immobilize as much as 200 micromol of lipids per gram of dry resin. The amount of immobilized vesicles was decreased by a reduction of the proportion of the negatively charged lipids in the vesicles, indicating the importance of electrostatic interactions in the immobilization of the vesicles. The integrity of the vesicles was mostly preserved after the immobilization. This new polymer-peptide system was used easily and successfully to immobilize a membrane-bound enzyme, gamma-glutamyl transpeptidase. The activity of the membrane-bound enzyme was studied by monitoring the release of p-nitroaniline. The activity of the enzyme was still retained, even after being re-used eight times, indicating the strong immobilization of the enzyme in its active form. The polymer-peptide support could be regenerated by washing with ethanol and reused.

  2. Nanostructured assemblies from amphiphilic ABC multiblock polymers

    Science.gov (United States)

    Hillmyer, Marc A.

    2012-02-01

    Amphiphilic AB diblock copolymers containing a water compatible segment can self-assemble in aqueous media to give supramolecular structures that include simple spherical micelles and macromolecular vesicles termed polymersomes. Amphiphilic ABA triblocks with hydrophobic end blocks can adopt analogous structures but can also form gels at high polymer concentrations. The structural and chemical diversity demonstrated in block copolymer micelles and gels makes them attractive for applications ranging from drug delivery to personal care products to nanoreactors. The inclusion of a third block in amphiphilic ABC triblock systems can lead to a much wider array of self-assembled structures that depend not only on composition but also on block sequence, architecture and incompatibility considerations. I will present our recent efforts on tuning micelle and gel structure and behavior using controlled architecture ABC triblocks. The combination of diverse polymer segments into a single macromolecule is a powerful method for development of self-assembled structures with both new form and new function.

  3. Amphiphilic vinyl polymers effectively prolong liposome circulation time in vivo.

    Science.gov (United States)

    Torchilin, V P; Shtilman, M I; Trubetskoy, V S; Whiteman, K; Milstein, A M

    1994-10-12

    Newly synthesized amphiphilic polyacrylamide and poly(vinyl pyrrolidone), single terminus-modified with long-chain fatty acyl groups, are able to incorporate into the liposomal membrane, and similar to poly(ethylene glycol) prolong liposome circulation in vivo and decrease liposome accumulation in the liver. Protective efficacy of modified polymers increases with the increase in the length of acyl moiety and decreases for higher molecular weight polymers. The data on amphiphilic polymer-modified liposome biodistribution are presented.

  4. New synthetic amphiphilic polymers for steric protection of liposomes in vivo.

    Science.gov (United States)

    Torchilin, V P; Trubetskoy, V S; Whiteman, K R; Caliceti, P; Ferruti, P; Veronese, F M

    1995-09-01

    Carboxy group-terminated synthetic polymers--branched poly(ethylene glycol), poly(acryloylmorpholine), and poly(vinylpyrrolidone)--were made amphiphilic by derivatization with phosphatidyl ethanolamine via the terminal carboxy group and then incorporated into lecithin-cholesterol liposomes prepared by the detergent dialysis method. Following the biodistribution of liposomes in mice, all three polymers were shown to be effective steric protectors for liposomes and were able to sharply increase liposome circulation times in a concentration-dependent manner. The accumulation of liposomes in the liver decreases. The effects observed are similar to those found for liposomes modified with linear poly(ethylene glycol). At low polymer concentration, amphiphilic branched poly(ethylene glycol) seems to be the most effective liposome protector, most probably, because at the same molar content of anchoring groups, each attachment point carries two polymeric chains and doubles the quantity of liposome-grafted polymer comparing to linear poly(ethylene glycol).

  5. Polymer's anchoring behavior in liquid crystal cells

    Science.gov (United States)

    Cui, Yue

    The current dissertation mainly discusses about the polymers anchoring behavior in liquid crystal cells in two aspects: surface interaction and bulk interaction. The goal of the research is to understand the fundamental physics of anchoring strength and apply the knowledge to liquid crystal display devices. Researchers proposed two main contributors to the surface anchoring strength: the micro grooves generated by external force and the polymer chain's alignment. Both of them has experimental proofs. In the current study, explorations were made to understand the mechanisms of surface anchoring strength and easy axis of surface liquid crystal provided by rubbed polymer alignment layer. The work includes not only the variation of the alignment layer itself such as thickness(Chapter 3) and polymer side chain (Chapter 5), but also the variation of external conditions such as temperature (Chapter 4) and rubbing condition (Chapter 6). To determine the polar and azimuthal anchoring strengths, Rapini-Papoular's expression was applied. However, it was discovered that higher order terms may be required in order to fit the experimental result or theoretically predict unique anchoring behaviors (Chapter 2, Chapter 6). SEM and AFM technologies were introduced to gather the actual structures of polymer alignment layer and extrapolate the alignment of liquid crystal in a micro scale. The result shows that the anchoring strength can be adjusted by the layer thickness, side chain structure, while the easy axis direction can be adjusted by a second rubbing direction. In addition, different anchoring conditions combined with liquid crystal's elastic energy can generate quite different forms of liquid crystals (Chapter 7). In the study of bulk alignment, the main contrition from the current dissertation is applying the understanding of anchoring behavior to optimizing actual switchable devices. Conventional PDLC performance can be tuned with the knowledge of the polymer and the liquid

  6. Revealing Amphiphilic Nanodornains of Anti-Biofouling Polymer Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Amadei, CA; Yang, R; Chiesa, M; Gleason, KK; Santos, S

    2014-04-09

    Undesired bacterial adhesion and biofilm formation on wetted surfaces leads to significant economic and environmental costs in various industries. Amphiphilic coatings with molecular hydrophilic and hydrophobic patches can mitigate such biofouling effectively in an environmentally friendly manner. The coatings are synthesized by copolymerizing (Hydroxyethyl)methacrylate and perfluorodecylacrylate via initiated chemical vapor deposition (iCVD). In previous studies, the size of the patches was estimated to be similar to 1.4-1.75 nm by fitting protein adsorption data to a theoretical model. However, no direct observations of the molecular heterogeneity exist and therefore the origin of the fouling resistance of amphiphilic coatings remains unclear. Here, the amphiphilic nature is investigated by amplitude modulation atomic force microscopy (AM-AFM). High-resolution images obtained by penetrating and oscillating the AFM tip under the naturally present water layer with sub-nanometer amplitudes reveal, for the first time, the existence of amphiphilic nanodomains (1-2 nm(2)). Compositional heterogeneity at the nanoscale is further corroborated by a statistical analysis on the data obtained with dynamic AM-AFM force spectroscopy. Variations in the long range attractive forces, responsible for water affinity, are also identified. These nanoscopic results on the polymers wettability are also confirmed by contact angle measurements (i.e., static and dynamic). The unprecedented ability to visualize the amphiphilic nanodomains as well as sub-nanometer crystalline structures provides strong evidence for the existence of previously postulated nanostructures, and sheds light on the underlying antifouling mechanism of amphiphilic chemistry.

  7. High-Capacity Drug Carriers from Common Polymer Amphiphiles.

    Science.gov (United States)

    Zhou, Zhun; Munyaradzi, Oliver; Xia, Xin; Green, Da'Sean; Bong, Dennis

    2016-09-12

    We report herein a dual-purpose role for polyacidic domains in an aqueous-phase polymer amphiphile assembly. In addition to their typical role as ionized water-solubilizing and self-repulsive motifs, we find that polycarboxylic acid domains uniquely enable high levels of hydrophobic drug encapsulation. By attenuated total reflectance infrared spectroscopy, we find significant differences in the carbonyl stretching region of the nanoparticles formed by polyacidic amphiphiles relative to those in soluble, single-domain poly(acrylic acid), suggesting that stabilization may be derived from limited ionization of the carboxylate groups upon assembly. Acidic-hydrophobic diblock polyacrylates were prepared and coassembled with up to 60 wt % camptothecin (CPT) into nanoparticles, the highest loading reported to date. Controlled release of bioactive CPT from polymer nanoparticles is observed, as well as protection from human serum albumin-induced hydrolysis. Surface protection with PEG limits uptake of the CPT-loaded nanoparticles by MCF-7 breast cancer cells, as expected. Acidic-hydrophobic polymer amphiphiles thus have the hallmarks of a useful and general drug delivery platform and are readily accessible from living radical polymerization of cheap, commercially available monomers. We highlight here the potential utility of this common polymer design in high-capacity, controlled-release polymer nanoparticle systems. PMID:27476544

  8. Function of Amphiphilic Biomolecular Machines: Elastic Protein-based Polymers

    Science.gov (United States)

    Urry, Dan W.

    2000-03-01

    Elastic protein-based polymers function as biomolecular machines due to inverse temperature transitions of hydrophobic folding and assembly. The transitions occur either on raising the temperature from below to above the transition temperature, Tt, or on isothermally lowering Tt from above to below an operating temperature. The inverse temperature transition involves a decrease in entropy of the polymer component of the system on raising the temperature and a larger increase in solvent entropy on hydrophobic association. Tt depends on the quantity of hydrophobic hydration that undergoes transition to bulk water. Designed amphiphilic polymers perform free energy transductions involving the intensive variables of mechanical force, pressure, temperature, chemical potential, electrochemical potential and electromagnetic radiation and define a set of five axioms for their function as machines. The physical basis for these diverse energy conversions is competition for hydration between apolar (hydrophobic) and polar (e.g., charged) moieties. The effectiveness of these Tt-type entropic elastic protein-based machines is due to repeating peptide sequences that form regular, dynamic repeating structures and exhibit damping of backbone torsional oscillations on extension.

  9. Intra-chain organisation of hydrophobic residues controls inter-chain aggregation rates of amphiphilic polymers

    CERN Document Server

    Varilly, Patrick; Kirkegaard, Julius B; Knowles, Tuomas P J; Chandler, David

    2016-01-01

    Aggregation of amphiphiles through the action of hydrophobic interactions is a common feature in soft condensed matter systems and is of particular importance in the context of biophysics as it underlies both the generation of functional biological machinery as well as the formation of pathological misassembled states of proteins. Here we explore the aggregation behaviour of amphiphilic polymers using lattice Monte-Carlo calculations and show that the distribution of hydrophobic residues within the polymer sequence determines the facility with which dry/wet interfaces can be created and that such interfaces drive the aggregation process.

  10. Amphiphilic semi-interpenetrating polymer networks using pulverized rubber

    Science.gov (United States)

    Shahidi, Nima

    Scrap rubber materials provide a significant challenge to either reuse or safe disposal. Every year, millions of tires are discarded to landfills in the United States, consuming a staggering amount of land space, creating a high risk for large fires, breeding mosquitoes that spread diseases, and wasting the planet's natural resources. This situation cannot be sustained. The challenge of reusing scrap rubber materials is mainly due to the crosslinked structure of vulcanized rubber that prevent them from melting and further processing for reuse. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. The production of fine rubber particles is generally accomplished through the use of a cryogenic process that is costly. Therefore, development of a cost effective technology that utilizes a large quantity of the scrap rubber materials to produce high value added materials is an essential element in maintaining a sustainable solution to rubber recycling. In this research, a cost effective pulverization process, solid state shear extrusion (SSSE), was modified and used for continuous pulverization of the rubber into fine particles. In the modified SSSE process, pulverization takes place at high compressive shear forces and a controlled temperature. Furthermore, an innovative particle modification process was developed to enhance the chemical structure and surface properties of the rubber particles for manufacturing of high value added products. Modification of rubber particles was accomplished through the polymerization of a hydrophilic monomer mixture within the intermolecular structure of the hydrophobic rubber particles. The resulting composite particles are considered as amphiphilic particulate phase semi-interpenetrating polymer networks (PPSIPNs). The modified rubber particles are water dispersible and suitable for use in a variety of aqueous media

  11. Single-chain crosslinked star polymers via intramolecular crosslinking of self-folding amphiphilic copolymers in water

    OpenAIRE

    Terashima, Takaya; Sugita, Takanori; Sawamoto, Mitsuo

    2015-01-01

    Single-chain crosslinked star polymers with multiple hydrophilic short arms and a hydrophobic core were created as novel microgel star polymers of single polymer chains. The synthetic process involves the intramolecular crosslinking of self-folding amphiphilic random copolymers in water. For this process, amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic olefin pendants were synthesized by ruthenium-catalyzed living radical copolymerization of PEG m...

  12. MODIFICATION OF PALLADIUM METALLIC CATALYST WITH POLYMER-ANCHORED THIOETHER LIGANDS

    Institute of Scientific and Technical Information of China (English)

    LIU Hanfan; MAO Guoping

    1993-01-01

    A well-dispersed metallic palladium catalyst modified by polymer-anchored thioether ligands was used for the hydrogenation of cyclopentadiene to cyclopentene with high activity and selectivity in ambient condition. The evidences to show the modification of catalytic properties by polymer anchored ligands were given.

  13. Micellar interactions in water-AOT based droplet microemulsions containing hydrophilic and amphiphilic polymers

    Science.gov (United States)

    Appel, Markus; Spehr, Tinka Luise; Wipf, Robert; Moers, Christian; Frey, Holger; Stühn, Bernd

    2013-11-01

    We investigate the influence of addition of hydrophilic and amphiphilic polymer on percolation behavior and micellar interactions in AOT-based water-in-oil droplet microemulsions. We focus on two series of samples having constant molar water to surfactant ratio W = 20 and constant droplet volume fraction Φ = 30%, respectively. From dielectric spectroscopy experiments, we extract the bending rigidity of the surfactant shell by percolation temperature measurements. Depending on droplet size, we find stabilization and destabilization of the surfactant shell upon addition of hydrophilic poly(ethylene glycol) (PEG) (Mn = 3100 g mol-1) and amphiphilic poly(styrene)-b-poly(ethylene glycol) copolymer with comparable length of the hydrophilic block. Complementary small angle X-ray scattering experiments corroborate the finding of stabilization for smaller droplets and destabilization of larger droplets. Subsequent analysis of dielectric spectra enables us to extract detailed information about micellar interactions and clustering by evaluating the dielectric high frequency shell relaxation. We interpret the observed results as a possible modification of the inter-droplet charge transfer efficiency by addition of PEG polymer, while the amphiphilic polymer shows a comparable, but dampened effect.

  14. Hydration-Induced Phase Separation in Amphiphilic Polymer Matrices and its Influence on Voclosporin Release

    Energy Technology Data Exchange (ETDEWEB)

    Khan, I. John [The State Univ. of New Jersey, Piscataway, NJ (United States); Murthy, N. Sanjeeva [The State Univ. of New Jersey, Piscataway, NJ (United States); Kohn, Joachim [The State Univ. of New Jersey, Piscataway, NJ (United States)

    2015-10-30

    Voclosporin is a highly potent, new cyclosporine -- a derivative that is currently in Phase 3 clinical trials in the USA as a potential treatment for inflammatory diseases of the eye. Voclosporin represents a number of very sparingly soluble drugs that are difficult to administer. It was selected as a model drug that is dispersed within amphiphilic polymer matrices, and investigated the changing morphology of the matrices using neutron and x-ray scattering during voclosporin release and polymer resorption. The hydrophobic segments of the amphiphilic polymer chain are comprised of desaminotyrosyl-tyrosine ethyl ester (DTE) and desaminotyrosyl-tyrosine (DT), and the hydrophilic component is poly(ethylene glycol) (PEG). Water uptake in these matrices resulted in the phase separation of hydrophobic and hydrophilic domains that are a few hundred Angstroms apart. These water-driven morphological changes influenced the release profile of voclosporin and facilitated a burst-free release from the polymer. No such morphological reorganization was observed in poly(lactide-co-glycolide) (PLGA), which exhibits an extended lag period, followed by a burst-like release of voclosporin when the polymer was degraded. An understanding of the effect of polymer composition on the hydration behavior is central to understanding and controlling the phase behavior and resorption characteristics of the matrix for achieving long-term controlled release of hydrophobic drugs such as voclosporin.

  15. Amphiphilic block copolymers as efficiency boosters in microemulsions a SANS investigation of the role of polymers

    CERN Document Server

    Endo, H; Mihailescu, M; Monkenbusch, M; Gompper, G; Richter, D; Jakobs, B; Sottmann, T; Strey, R

    2002-01-01

    The effect of amphiphilic block copolymers on ternary microemulsions (water, oil and non-ionic surfactant) is investigated. Small amounts of PEP-PEO block copolymer lead to a dramatic expansion of the one-phase region where water and oil can be solubilized by the mediation of surfactant molecules. Small-angle neutron-scattering experiments employing a high-precision two-dimensional contrast-variation technique demonstrate that the polymer is distributed uniformly on the surfactant membrane, where it modifies the membrane curvature elasticity. Furthermore, a new approach to determine the bending rigidity of an amphiphilic membrane is proposed, which is precise enough to measure the logarithmic scale dependence of the bending rigidity and its universal prefactor in bicontinuous microemulsions. (orig.)

  16. Amphiphilic nanocapsules entangled with organometallic coordination polymers for controlled cargo release.

    Science.gov (United States)

    Liang, Guodong; Ni, Huan; Bao, Suping; Zhu, Fangming; Gao, Haiyang; Wu, Qing; Tang, Ben Zhong

    2014-06-01

    A class of new amphiphilic nanocapsules entangled with organometallic coordination polymers has been developed for the first time. Poly(2-(N,N-dimethyl amino)ethyl methacrylate)-b-polystyrene capped with β-cyclodextrin (β-CD) (CD-PDMAEMA-b-PS) is first synthesized using sequent RAFT polymerization of styrene and 2-(N,N-dimethyl amino)ethyl methacrylate with xanthate modified β-CD as chain transfer agent. The end group of β-CD is allowed to include 4,4'-bipyridine through host-guest inclusion to yield PDMAEMA-b-PS terminated with an inclusion complex of β-CD and bipyridine (bpy-PDMAEMA-b-PS), which is then used as surfactant to prepare emulsion droplets in toluene/water mixture. Upon addition of Ni(II), bipyridine coordinates with Ni(II) to form coordination polymers in the periphery of emulsion droplets, affording amphiphilic capsules entangled with organometallic coordination polymers, as confirmed by GPC, (1)H NMR, SEM, TEM, DLS, and so on. The organometallic coordination polymer capsules are capable of encapsulating organic cargoes. Interestingly, encapsulated cargoes can be extracted from the capsules without damaging the capsules. Such capsules are potential candidates for encapsulating and controlled release of organic cargoes. PMID:24828951

  17. Research developments on amphiphilic hyperbranched polymers%两亲性超支化聚合物研究进展

    Institute of Scientific and Technical Information of China (English)

    强涛涛; 张国国; 王学川

    2013-01-01

    In this paper, the research progress in amphiphilic hyperbranched polymers is overviewed. Synthetic methods of amphiphilic hyperbranched polymers are introduced, which covers the modification of end groups of the hyperbranched polymers with long chain alkyl and polyethylene glycol, and the polymerization of vinyl derivatives through free radical polymerization or ring-opening polymerization, using hyperbranched polymers as macroinitiator. Different structures of amphiphilic hyperbranched polymers have their unique properties in solution, such as core-shell unimolecule micelles and different micellar conformation aggregates. Moreover, the application of amphiphilic hyperbranched polymers, such as drug delivery carrier, material modification, and the encapsulation of dye molecules is also introduced. Then, the development trend of amphiphilic hyperbranched polymers is proposed. The preparation of special properties of amphiphilic hyperbranched polymers and the application of amphiphilic hyperbranched polymers in biological medicine should be the main focus in the development of amphiphilic hyperbranched polymers.%介绍了两亲性超支化聚合物的合成方法,利用长链烷基和聚乙二醇对超支化聚合物端基接枝改性;或者对超支化聚合物改性引入活性位点,再利用其引发乙烯基单体,通过自由基聚合、开环聚合得到两亲性超支化聚合物.阐述了不同结构的两亲性超支化聚合物在溶液中的独特性质,如核壳型单分子胶束以及不同胶束形态的聚集体.详细介绍了两亲性超支化聚合物在药物输送载体、材料改性以及染料分子的封装等领域的应用现状,指出采用新的改性技术、聚合技术制备具有特殊性能的两亲性超支化聚合物以及探索其在生物医药领域的研究为今后的主要发展方向.

  18. STUDIES ON SELF-ASSOCIATIVE BEHAVIOR OF A NOVEL CATION AMPHIPHILIC POLYMER

    Institute of Scientific and Technical Information of China (English)

    Jing Li; Fei-peng Wu; Er-jian Wang

    2009-01-01

    A novel associating polymer P(AEBA) was synthesized by radical polymerization of the cationic amphiphilic monomer, 4-(2-(acryloyloxy)ethoxy)benzyl tri-ethyl ammonium bromide (AEBA), in aqueous solutions. P(AEBA) displays a strong tendency for self-association in aqueous solutions and is sensitive to the external stimulation such as added salt. The associative properties and morphologies of P(AEBA) were studied by fluorescnece probe technique, viscometry and TEM. In dilute salt-free solutions P(AEBA) behaves as polyelectrolyte, while its behavior is similar to that of the polysoap as salt added. Accompanying increasing polymer concentration, polymer aggregation conformation changes from an extended necklace-like structure to a compact globular aggregate corresponding to the viscosity reduction.

  19. A novel durable intelligent fiber reinforced polymer anchor with embedded optical fiber Bragg grating sensors

    Institute of Scientific and Technical Information of China (English)

    HUANG MingHua; ZHOU Zhi; YUE Shuai; HE JianPing; OU JinPing

    2012-01-01

    Anchors are the key members of the geotechnical anchorage engineering,it is urgent to monitor their behavior in service for preventing the potential risks.This paper proposes a novel durable intelligent fiber reinforced polymer (FRP) anchor to understand the behavior of the anchor in the field application.Series of optical fiber Bmgg grating (FBG) sensors were embedded into the central axis along the anchor to sense itself axial strain variations.An evolution model of axial strain was also developed to evaluate the behavior along the anchor.A demonstration test was carried out to test its self-sensing properties in the laboratory.The experimental results indicated that the embedded FBG sensors monitored the behavior,e.g.axial strain/interfacial damage evolutions along the anchor and displacement/applied load at the pulling end effectively,without influence from the interfacial compression and slip effects.

  20. Screening nylon-3 polymers, a new class of cationic amphiphiles, for siRNA delivery.

    Science.gov (United States)

    Nadithe, Venkatareddy; Liu, Runhui; Killinger, Bryan A; Movassaghian, Sara; Kim, Na Hyung; Moszczynska, Anna B; Masters, Kristyn S; Gellman, Samuel H; Merkel, Olivia M

    2015-02-01

    Amphiphilic nucleic acid carriers have attracted strong interest. Three groups of nylon-3 copolymers (poly-β-peptides) possessing different cationic/hydrophobic content were evaluated as siRNA delivery agents in this study. Their ability to condense siRNA was determined in SYBR Gold assays. Their cytotoxicity was tested by MTT assays, their efficiency of delivering Alexa Fluor-488-labeled siRNA intracellularly in the presence and absence of uptake inhibitors was assessed by flow cytometry, and their transfection efficacies were studied by luciferase knockdown in a cell line stably expressing luciferase (H1299/Luc). Endosomal release was determined by confocal laser scanning microscopy and colocalization with lysotracker. All polymers efficiently condensed siRNA at nitrogen-to-phosphate (N/P) ratios of 5 or lower, as reflected in hydrodynamic diameters smaller than that at N/P 1. Although several formulations had negative zeta potentials at N/P 1, G2C and G2D polyplexes yielded >80% uptake in H1299/Luc cells, as determined by flow cytometry. Luciferase knockdown (20-65%) was observed after transfection with polyplexes made of the high molecular weight polymers that were the most hydrophobic. The ability of nylon-3 polymers to deliver siRNA intracellularly even at negative zeta potential implies that they mediate transport across cell membranes based on their amphiphilicity. The cellular uptake route was determined to strongly depend on the presence of cholesterol in the cell membrane. These polymers are, therefore, very promising for siRNA delivery at reduced surface charge and toxicity. Our study identified nylon-3 formulations at low N/P ratios for effective gene knockdown, indicating that nylon-3 polymers are a new, promising type of gene delivery agent. PMID:25437915

  1. Aggregation of amphiphilic polymers in the presence of adhesive small colloidal particles

    Science.gov (United States)

    Baulin, Vladimir A.; Johner, Albert; Avalos, Josep Bonet

    2010-11-01

    The interaction of amphiphilic polymers with small colloids, capable to reversibly stick onto the chains, is studied. Adhesive small colloids in solution are able to dynamically bind two polymer segments. This association leads to topological changes in the polymer network configurations, such as looping and cross-linking, although the reversible adhesion permits the colloid to slide along the chain backbone. Previous analyses only consider static topologies in the chain network. We show that the sliding degree of freedom ensures the dominance of small loops, over other structures, giving rise to a new perspective in the analysis of the problem. The results are applied to the analysis of the equilibrium between colloidal particles and star polymers, as well as to block copolymer micelles. The results are relevant for the reversible adsorption of silica particles onto hydrophilic polymers, used in the process of formation of mesoporous materials of the type SBA or MCM, cross-linked cyclodextrin molecules threading on the polymers and forming the structures known as polyrotaxanes. Adhesion of colloids on the corona of the latter induce micellization and growth of larger micelles as the number of colloids increase, in agreement with experimental data.

  2. Polypeptoids from N -Substituted Glycine N -Carboxyanhydrides: Hydrophilic, Hydrophobic, and Amphiphilic Polymers with Poisson Distribution

    KAUST Repository

    Fetsch, Corinna

    2011-09-13

    Preparation of defined and functional polymers has been one of the hottest topics in polymer science and drug delivery in the recent decade. Also, research on (bio)degradable polymers gains more and more interest, in particular at the interface of these two disciplines. However, in the majority of cases, combination of definition, functionality and degradability, is problematic. Here we present the preparation and characterization (MALDI-ToF MS, NMR, GPC) of nonionic hydrophilic, hydrophobic, and amphiphilic N-substituted polyglycines (polypeptoids), which are expected to be main-chain degradable and are able to disperse a hydrophobic model compound in aqueous media. Polymerization kinetics suggest that the polymerization is well controlled with strictly linear pseudo first-order kinetic plots to high monomer consumption. Moreover, molar mass distributions of products are Poisson-type and molar mass can be controlled by the monomer to initiator ratio. The presented polymer platform is nonionic, backbone degradable, and synthetically highly flexible and may therefore be valuable for a broad range of applications, in particular as a biomaterial. © 2011 American Chemical Society.

  3. Development of controlled release formulations of imidacloprid employing novel nano-ranged amphiphilic polymers.

    Science.gov (United States)

    Adak, Totan; Kumar, Jitendra; Shakil, N A; Walia, S

    2012-01-01

    Amphiphilic copolymers, synthesized from poly (ethylene glycols) and various aliphatic diacids, which self assemble into nano-micellar aggregates in aqueous media, were used to develop controlled release (CR) formulations of imidacloprid [1-(6 chloro-3-pyridinyl methyl)-N-nitro imidazolidin-2-ylideneamine] using encapsulation technique. High solubilisation power and low critical micelle concentration (CMC) of these amphiphilic polymers may increase the efficacy of formulations. Formulations were characterised by Infrared (IR) spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Encapsulation efficiency, loading capacity and stability after accelerated storage test of the developed formulations were checked. The kinetics of imidacloprid release in water from the different formulations was studied. Release from the commercial formulation was faster than the CR formulations. The diffusion exponent (n value) of imidacloprid, in water ranged from 0.22 to 0.37 in the tested formulations. While the time taken for release of 50 % of imidacloprid ranged from 2.32 to 9.31 days for the CR formulations. The developed CR formulations can be used for efficient pest management in different crops. PMID:22375594

  4. Self-Assembling Nanoparticles of Amphiphilic Polymers for In Vitro and In Vivo FRET Imaging.

    Science.gov (United States)

    Garcia-Amorós, Jaume; Tang, Sicheng; Zhang, Yang; Thapaliya, Ek Raj; Raymo, Françisco M

    2016-01-01

    Self-assembling nanoparticles of amphiphilic polymers are viable delivery vehicles for transporting hydrophobic molecules across hydrophilic media. Noncovalent contacts between the hydrophobic domains of their macromolecular components are responsible for their formation and for providing a nonpolar environment for the encapsulated guests. However, such interactions are reversible and, as a result, these supramolecular hosts can dissociate into their constituents amphiphiles to release the encapsulated cargo. Operating principles to probe the integrity of the nanocarriers and the dynamic exchange of their components are, therefore, essential to monitor the fate of these supramolecular assemblies in biological media. The co-encapsulation of complementary chromophores within their nonpolar interior offers the opportunity to assess their stability on the basis of energy transfer and fluorescence measurements. Indeed, the exchange of excitation energy between the entrapped chromophores can only occur if the nanoparticles retain their integrity to maintain donors and acceptors in close proximity. In fact, energy-transfer schemes are becoming invaluable protocols to elucidate the transport properties of these fascinating supramolecular constructs in a diversity of biological preparations and can facilitate the identification of strategies to deliver contrast agents and/or drugs to target locations in living organisms for potential diagnostic and/or therapeutic applications. PMID:26589505

  5. High-performance Polymer Membranes with Multi-functional Amphiphilic Micelles for CO2 Capture.

    Science.gov (United States)

    Kim, Sang Jin; Jeon, Harim; Kim, Dong Jun; Kim, Jong Hak

    2015-11-01

    Herein, we report a high performance polymer membrane with simultaneously large improvements in the CO2 permeability and CO2/N2 selectivity. These improvements are obtained by incorporation of a multi-functional amphiphilic comb copolymer micelle, that is, poly(dimethylsiloxane)-g-poly(oxyethylene methacrylate) (PDMS-g-POEM), into a poly(amide-b-ethylene oxide) (Pebax) matrix. Both CO2 and N2 permeabilities continuously increased with PDMS-g-POEM content, whereas the CO2/N2 selectivity increased up to 40 wt % of PDMS-g-POEM, which enabled the maximum performance to approach the upper bound limit (2008). The membranes with PDMS-g-POEM exhibited greater CO2 permeability and CO2/N2 selectivity than those with a zeolitic imidazolate framework (ZIF-8), a well-known expensive inorganic filler, indicating the effectiveness of PDMS-g-POEM micelles for CO2 capture.

  6. Recent advances in amphiphilic polymers for simultaneous delivery of hydrophobic and hydrophilic drugs.

    Science.gov (United States)

    Martin, Chloe; Aibani, Noorjahan; Callan, John F; Callan, Bridgeen

    2016-01-01

    Nanomedicine has evolved with the use of biological compounds such as proteins, peptides and DNA. These hydrophilic and often highly charged compounds require a delivery system to allow effective transport and release at the site of action. These new biological therapeutics have not replaced the more traditional smaller molecule, but instead are working synergistically to the benefit of the end user. To that end, drug delivery systems are now required to encapsulate both larger hydrophilic compounds as well as the smaller and generally more hydrophobic compound. This review highlights the emerging role in drug delivery of amphiphilic polymers that by their very nature can associate with compounds of differing physicochemical properties, in particular the role of micelles, polymersomes and nanocapsules.

  7. Novel functional materials from renewable lipids: Amphiphilic antimicrobial polymers and latent heat thermal energy storage

    Science.gov (United States)

    Floros, Michael Christopher

    Vegetable oils represent an ideal and renewable feedstock for the synthesis of a variety of functional materials. However, without financial incentive or unique applications motivating a switch, commercial products continue to be manufactured from petrochemical resources. Two different families of high value, functional materials synthesized from vegetable oils were studied. These materials demonstrate superior and unique performance to comparable petrochemical analogues currently on the market. In the first approach, 3 amphiphilic thermoplastic polytriazoles with differing lipophilic segment lengths were synthesized in a polymerization process without solvents or catalysts. Investigation of monomer structure influence on the resultant functional behaviour of these polymers found distinctive odd/even behaviour reliant on the number of carbon atoms in the monomers. Higher concentrations of triazole groups, due to shorter CH2 chains in the monomeric dialkynes, resulted in more brittle polymers, displaying higher tensile strengths but reduced elongation to break characteristics. These polymers had similar properties to commercial petroleum derived thermoplastics. One polymer demonstrated self-assembled surface microstructuring, and displayed hydrophobic properties. Antimicrobial efficacy of the polymers were tested by applying concentrated bacterial solutions to the surfaces, and near complete inhibition was demonstrated after 4 hours. Scanning electron microscope images of killed bacteria showed extensive membrane damage, consistent with the observed impact of other amphiphilic compounds in literature. These polytriazoles are suited for applications in medical devices and implants, where major concerns over antibiotic resistance are prevalent. In the second approach, a series of symmetric, saturated diester phase change materials (PCMs) were also synthesized with superior latent heat values compared to commercial petrochemical analogues. These diesters exhibit

  8. Alkyl Passivation and Amphiphilic Polymer Coating of Silicon Nanocrystals for Diagnostic Imaging

    Science.gov (United States)

    Hessel, Colin M.; Rasch, Michael R.; Hueso, Jose L.; Goodfellow, Brian W.; Akhavan, Vahid A.; Puvanakrishnan, Priyaveena; Tunnell, James W.

    2011-01-01

    We show a method to produce biocompatible polymer-coated silicon (Si) nanocrystals for medical imaging. Silica-embedded Si nanocrystals are formed by HSQ thermolysis. The nanocrystals are then liberated from the oxide and terminated with Si-H bonds by HF etching, followed by alkyl monolayer passivation by thermal hydrosilylation. The Si nanocrystals have an average diameter of 2.1 ± 0.6 nm and photoluminesce (PL) with a peak emission wavelength of 650 nm, which lies within the transmission window of 650–900 nm that is useful for biological imaging. The hydrophobic Si nanocrystals are then coated with an amphiphilic polymer for dispersion in aqueous media with pH ranging between 7 and 10 and ionic strength between 30 mM and 2 M, while maintaining a bright and stable PL and a hydrodynamic radius of only 20 nm. Fluorescence imaging of polymer-coated Si nanocrystals in a biological tissue host is demonstrated, showing the potential for in vivo imaging. PMID:20818646

  9. Highly polarized emission of the liquid crystalline conjugated polymer by controlling the surface anchoring energy

    Science.gov (United States)

    In Jo, Soo; Kim, Youngsik; Baek, Ji-Ho; Yu, Chang-Jae; Kim, Jae-Hoon

    2014-01-01

    We demonstrated a highly polarized organic light-emitting diode (OLED) through the enhancement of the orientational ordering of the emitting polymer with a nematic liquid crystalline (LC) phase. The highly ordered state of the conjugate polymer was obtained by thermal annealing at the nematic temperature and strong azimuthal anchoring energy of the underlying polyimide. The order parameter of the conjugate polymer was analyzed using a second-harmonic generation model and the dichroic ratio was measured to be 22 : 1. Also, we applied our optimized OLED with high optical polarizability to an effective light source for a twisted nematic LC display.

  10. Determination of Concentration of Amphiphilic Polymer Molecules on the Surface of Encapsulated Semiconductor Nanocrystals.

    Science.gov (United States)

    Fedosyuk, Aleksandra; Radchanka, Aliaksandra; Antanovich, Artsiom; Prudnikau, Anatol; Kvach, Maksim V; Shmanai, Vadim; Artemyev, Mikhail

    2016-03-01

    We present a method for the determination of the average number of polymer molecules on the surface of A(II)B(VI) luminescent core-shell nanocrystals (CdSe/ZnS, ZnSe/ZnS quantum dots, and CdS/ZnS nanorods) encapsulated with amphiphilic polymer. Poly(maleic anhydride-alt-1-tetradecene) (PMAT) was quantitatively labeled with amino-derivative of fluorescein and the average amount of PMAT molecules per single nanocrystal was determined using optical absorption of the dye in the visible spectral range. The average amount of PMAT molecules grows linearly with the surface area of all studied nanocrystals. However, the surface density of the monomer units increases nonlinearly with the surface area, because of the increased competition between PMAT molecules for Zn-hexanethiol surface binding sites. The average value of zeta potential (ζ = -35 mV) was found to be independent of the size, shape, and chemical composition of nanocrystals at fixed buffer parameters (carbonate-bicarbonate buffer, pH 9.5 and 5 mM ionic strength). This finding is expected to be useful for the determination of the surface density of remaining carboxyl groups in PMAT-encapsulated nanocrystals. PMID:26866303

  11. Searching for low percolation thresholds within amphiphilic polymer membranes: The effect of side chain branching

    Science.gov (United States)

    Dorenbos, G.

    2015-06-01

    Percolation thresholds for solvent diffusion within hydrated model polymeric membranes are derived from dissipative particle dynamics in combination with Monte Carlo (MC) tracer diffusion calculations. The polymer backbones are composed of hydrophobic A beads to which at regular intervals Y-shaped side chains are attached. Each side chain is composed of eight A beads and contains two identical branches that are each terminated with a pendant hydrophilic C bead. Four types of side chains are considered for which the two branches (each represented as [C], [AC], [AAC], or [AAAC]) are splitting off from the 8th, 6th, 4th, or 2nd A bead, respectively. Water diffusion through the phase separated water containing pore networks is deduced from MC tracer diffusion calculations. The percolation threshold for the architectures containing the [C] and [AC] branches is at a water volume fraction of ˜0.07 and 0.08, respectively. These are much lower than those derived earlier for linear architectures of various side chain length and side chain distributions. Control of side chain architecture is thus a very interesting design parameter to decrease the percolation threshold for solvent and proton transports within flexible amphiphilic polymer membranes.

  12. Searching for low percolation thresholds within amphiphilic polymer membranes: The effect of side chain branching

    Energy Technology Data Exchange (ETDEWEB)

    Dorenbos, G., E-mail: dorenbos@ny.thn.ne.jp [Sano 1107-2, Belle Crea 502, Susono 410-1118 (Japan)

    2015-06-14

    Percolation thresholds for solvent diffusion within hydrated model polymeric membranes are derived from dissipative particle dynamics in combination with Monte Carlo (MC) tracer diffusion calculations. The polymer backbones are composed of hydrophobic A beads to which at regular intervals Y-shaped side chains are attached. Each side chain is composed of eight A beads and contains two identical branches that are each terminated with a pendant hydrophilic C bead. Four types of side chains are considered for which the two branches (each represented as [C], [AC], [AAC], or [AAAC]) are splitting off from the 8th, 6th, 4th, or 2nd A bead, respectively. Water diffusion through the phase separated water containing pore networks is deduced from MC tracer diffusion calculations. The percolation threshold for the architectures containing the [C] and [AC] branches is at a water volume fraction of ∼0.07 and 0.08, respectively. These are much lower than those derived earlier for linear architectures of various side chain length and side chain distributions. Control of side chain architecture is thus a very interesting design parameter to decrease the percolation threshold for solvent and proton transports within flexible amphiphilic polymer membranes.

  13. Release kinetics of an amphiphilic photosensitizer by block-polymer nanoparticles.

    Science.gov (United States)

    Kerdous, Rachid; Sureau, Franck; Bour, Aurélien; Bonneau, Stéphanie

    2015-11-30

    Block-polymer nanoparticles are now well-known candidates for the delivery of various non-soluble drugs to cells. The release of drugs from these nanoparticles is a major concern related to their efficiency as nanovectors and is still not completely deciphered. Various processes have been identified, depending of both the nature of the block-polymer and those of the drugs used. We focused our interest on an amphiphilic photosensitizer studied for photodynamic treatments of cancer, Pheophorbide-a (Pheo). We studied the transfer of Pheo from poly(ethyleneglycol-b-ϵ-caprolactone) nanoparticles (I) to MCF-7 cancer cells and (II) to models of membranes. Altogether, our results suggest that the delivery of the major part of the Pheo by the nanoparticles occurs via a direct transfer of Pheo from the nanoparticles to the membrane, by collision. A minor process may involve the internalization of a small amount of the nanoplatforms by the cells. So, this research illustrates the great care necessary to address the question of the choice of such nanocarriers, in relation with the properties - in particular the relative hydrophobicity - of the drugs encapsulated, and gives elements to predict the mechanism and the efficiency of the delivery. PMID:26387620

  14. Control of the anchoring behavior of polymer-dispersed liquid crystals: effect of branching in the side chains of polyacrylates.

    Science.gov (United States)

    Zhou, Jian; Collard, David M; Park, Jung O; Srinivasarao, Mohan

    2002-08-28

    A temperature-driven anchoring transition in a polymer/nematic fluid composite that is far from the bulk nematic-isotropic transition temperature is reported. A series of poly(methylheptyl acrylates) were studied to probe the subtle effects of the side chain structure of the polymer on control of the anchoring. A polymer-dispersed liquid crystal film made from TL205 and 1-methylheptyl acrylate shows only planar anchoring over the temperature range studied, while the films made from TL205 and each of the other methylheptyl acrylates or n-heptyl acrylate show the homeotropic-to-planar anchoring transition at temperatures between 70 and 78 degrees C. An interfacial model is proposed in which the different conformation of the side chains is suggested as the cause for the dramatic difference in the observed anchoring behavior. PMID:12188649

  15. Synthesis of biodegradable amphiphilic Y-shaped block co-polymers via ring-opening polymerization for drug delivery.

    Science.gov (United States)

    Jia, Lin; Yan, Lifeng; Li, Yang

    2011-01-01

    A series of novel Y-shaped biodegradable block co-polymers of poly(ε-caprolactone) (PCL) and poly(ethyl ethylene phosphate) (PEEP) (PCL-(PEEP)2) were synthesized via ring-opening polymerization (ROP) of EEP with bis-hydroxy-functional ROP initiator (init-PCL-(OH)2). The init-PCL-(OH)2 was synthesized by ROP of CL using 4-hydroxybutyl acrylate (HBA) as initiator and L-tartaric acid as catalyst in bulk, and subsequently the resulting vinyl-terminated PCL was end-capped by acetyl chloride, followed by Michael addition using excess diethanolamine. The Y-shaped co-polymers and their intermediates were characterized by (1)H-, (13)C-, (31)P-NMR, FT-IR and gel-permeation chromatography. The results indicated that the molecular weight of the Y-shaped co-polymers increased with the increasing of the molar ratios of EEP to init-PCL-(OH)2 in the feed, while the PCL chain length was kept constant. The amphiphilic block co-polymers could self-assemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering, (1)H-NMR and atomic force microscopy. A study of controlled release of indomethacin indicated that the amphiphilic block co-polymers could potentially provide novel vehicles for drug delivery.

  16. Porphyrin effect on the surface morphology of amphiphilic polymers as observed by atomic force microscopy.

    Science.gov (United States)

    Kotova, S L; Timofeeva, V A; Belkova, G V; Aksenova, N A; Solovieva, A B

    2012-02-01

    Complexes of porphyrin photosensitizers (PPS) with triblock copolymers of ethylene- and propylene oxide - Pluronics(®) - exhibit markedly increased activity in the generation of singlet oxygen in aqueous media, as compared to pure porphyrins. Pluronics are amphiphilic polymers with surfactant properties suitable for a number of medical applications. PPS-Pluronic systems are considered as promising agents for photodynamic therapy which implies generation of singlet oxygen in the water-based human tissue. Importantly, Pluronics are capable of solubilization of not only water-soluble, but also hydrophobic PPS providing their transfer into the aqueous phase. It has been shown earlier that specific interactions of PPS with Pluronics must play a primary role for the photocatalytic properties of PPS-Pluronic systems. In the process of solubilization of a hydrophobic porphyrin by a Pluronic, both components are dissolved in an organic solvent, which is then removed, and the dry film is re-dissolved in water. Apparently, the initial binding between the porphyrin and the lipophilic part of the polymer takes place already at the stage of the film formation. We applied atomic force microscopy (AFM) to visualize structures formed by Pluronics upon their interactions with meso-tetraphenylporphyrin (TPP). We studied the surface structure of Pluronics(®) F87, F108 and F127 crystallized alone or together with TPP on silicon substrates from chloroform solutions. We found Pluronics to form similar dendritic structures independently of their molecular weight and degree of hydrophobicity. In the presence of TPP, though, we observed formation of distinct convex structures on top of the Pluronic dendrites. These structures appeared to consist of multiple flat layers placed on top of each other. Their sizes varied among the three Pluronics. We believe that TPP aggregates interact with the hydrophobic units of Pluronics causing the polymer chains to pack themselves in a distinct manner

  17. Coordination Chemistry inside Polymeric Nanoreactors: Metal Migration and Cross-Exchange in Amphiphilic Core-Shell Polymer Latexes

    OpenAIRE

    Si Chen; Eric Manoury; Florence Gayet; Rinaldo Poli

    2016-01-01

    A well-defined amphiphilic core-shell polymer functionalized with bis(p-methoxy-phenylphosphino)phenylphosphine (BMOPPP) in the nanogel (NG) core has been obtained by a convergent RAFT polymerization in emulsion. This BMOPPP@NG and the previously-reported TPP@NG (TPP = triphenylphosphine) and core cross-linked micelles (L@CCM; L = TPP, BMOPPP) having a slightly different architecture were loaded with [Rh(acac)(CO)2] or [RhCl(COD)]2 to yield [Rh(acac)(CO)(L@Pol)] or [RhCl(COD)(L@Pol)] (Pol = C...

  18. Synthesis, Characterization, and Evaluation of a Novel Amphiphilic Polymer RGD-PEG-Chol for Target Drug Delivery System

    OpenAIRE

    Shi Zeng; Fengbo Wu; Bo Li; Xiangrong Song; Yu Zheng; Gu He; Cheng Peng; Wei Huang

    2014-01-01

    An amphiphilic polymer RGD-PEG-Chol which can be produced in large scale at a very low cost has been synthesized successfully. The synthesized intermediates and final products were characterized and confirmed by 1H nuclear magnetic resonance spectrum (1H NMR) and Fourier transform infrared spectrum (FT-IR). The paclitaxel- (PTX-) loaded liposomes based on RGD-PEG-Chol were then prepared by film formation method. The liposomes had a size within 100 nm and significantly enhanced the cytotoxicit...

  19. Water-in-water emulsions stabilized by non-amphiphilic interactions: polymer-dispersed lyotropic liquid crystals.

    Science.gov (United States)

    Simon, Karen A; Sejwal, Preeti; Gerecht, Ryan B; Luk, Yan-Yeung

    2007-01-30

    Emulsion systems involving surfactants are mainly driven by the separation of the hydrophobic interactions of the aliphatic chains from the hydrophilic interactions of amphiphilic molecules in water. In this study, we report an emulsion system that does not include amphiphilic molecules but molecules with functional groups that are completely solvated in water. These functional groups give rise to molecular interactions including hydrogen bonding, pi stacking, and salt bridging and are segregated into a dispersion of droplets forming a water-in-water emulsion. This water-in-water emulsion consists of dispersing droplets of a water-solvated biocompatible liquid crystal--disodium cromoglycate (DSCG)--in a continuous aqueous solution containing specific classes of water-soluble polymers. Whereas aqueous solutions of polyols support the formation of emulsions of spherical droplets consisting of lyotropic liquid crystal DSCG with long-term stability (for at least 30 days), aqueous solutions of polyamides afford droplets of DSCG in the shape of prolate ellipsoids that are stable for only 2 days. The DSCG liquid crystal in spherical droplets assumes a radial configuration in which the optical axis of the liquid crystal aligns perpendicular to the surface of the droplets but assumes a tangential configuration in prolate ellipsoids in which the optical axis of the liquid crystal aligns parallel to the surface of the droplet. Other classes of water-soluble polymers including polyethers, polycations, and polyanions do not afford a stable emulsion of DSCG droplets. Both the occurrence and the stability of this unique emulsion system can be rationalized on the basis of the functional groups of the polymer. The different configurations of the liquid crystal (DSCG) droplets were also found to correlate with the strength of the hydrogen bonding that can be formed by the functional groups on the polymer. PMID:17241072

  20. Self-consistent field theoretic simulations of amphiphilic triblock copolymer solutions: Polymer concentration and chain length effects

    Directory of Open Access Journals (Sweden)

    X.-G. Han

    2014-06-01

    Full Text Available Using the self-consistent field lattice model, polymer concentration φP and chain length N (keeping the length ratio of hydrophobic to hydrophilic blocks constant the effects on temperature-dependent behavior of micelles are studied, in amphiphilic symmetric ABA triblock copolymer solutions. When chain length is increased, at fixed φP, micelles occur at higher temperature. The variations of average volume fraction of stickers φcos and the lattice site numbers Ncols at the micellar cores with temperature are dependent on N and φP, which demonstrates that the aggregation of micelles depends on N and φP. Moreover, when φP is increased, firstly a peak appears on the curve of specific heat CV for unimer-micelle transition, and then in addition a primary peak, the secondary peak, which results from the remicellization, is observed on the curve of CV. For a long chain, in intermediate and high concentration regimes, the shape of specific heat peak markedly changes, and the peak tends to be a more broad peak. Finally, the aggregation behavior of micelles is explained by the aggregation way of amphiphilic triblock copolymer. The obtained results are helpful in understanding the micellar aggregation process.

  1. Coordination Chemistry Inside Polymeric Nanoreactors: Interparticle Metal Exchange and Ionic Compound Vectorization in Phosphine-Functionalized Amphiphilic Polymer Latexes.

    Science.gov (United States)

    Chen, Si; Gayet, Florence; Manoury, Eric; Joumaa, Ahmad; Lansalot, Muriel; D'Agosto, Franck; Poli, Rinaldo

    2016-04-25

    Stable latexes of hierarchically organized core-cross-linked polymer micelles that are functionalized at the core with triphenylphosphine (TPP@CCM) have been investigated by NMR spectroscopic analysis at both natural (ca. pH 5) and strongly basic (pH 13.6) pH values after core swelling with toluene. The core-shell interface structuring forces part of the hydrophilic poly(ethylene oxide) (PEO) chains to reside inside the hydrophobic core at both pH values. Loading the particle cores with [Rh(acac)(CO)2 ] (acac=acetylacetonate) at various Rh/P ratios yielded polymer-supported [Rh(acac)(CO)(TPP)] (TPP=triphenylphosphine). The particle-to-particle rhodium migration is very fast at natural pH, but slows down dramatically at high pH, whereas the size distribution of the nanoreactors remains unchanged. The slow migration at pH 13.6 leads to the generation of polymer-anchored [Rh(OH)(CO)(TPP)2 ], which is also generated immediately upon the addition of NaOH to the particles with a [Rh(acac)(CO)] loading of 50 %. Similarly, treatment of the same particles with NaCl yielded polymer-anchored [RhCl(CO)(TPP)2 ]. Interparticle coupling occurs during these rapid processes. These experiments prove that the major contribution to metal migration is direct core-core contact. The slow migration at the high pH value, however, must result from a pathway that does not involve core-core contact. The facile penetration of the polymer cores by NaOH and NaCl results from the presence of shell-linked poly(ethylene oxide) methyl ether functions both outside and inside the polymer core-shell interface. PMID:27001452

  2. Characterization of Fe3O4/P(St-MPEO) Amphiphilic Magnetic Polymer Microspheres

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Amphiphilic magnetic microspheres consisting of styrene and poly(ethylene oxide) macromonomer(MPEO) were prepared by dispersion copolymerization in the presence of Fe3O4 magnetic fluid in an ethanol/water medium. The sizes of the magnetic microspheres and their distribution were characterized by means of scanning electron microscopy(SEM). The surface morphology and the average surface roughness of the microspheres were investigated by virtue of atomic force microscopy(AFM). It was found that the microspheres exhibit microscopic phase-separate and the mean square surface roughness of the microspheres increases with increasing MPEO used in the copolymerization. The amphiphilic magnetic microspheres containing 0.4-3.5 mg/g hydroxyl groups could be prepared from MPEO with different concentrations and styrene.

  3. Sustained release of protein from poly(ethylene glycol) incorporated amphiphilic comb like polymers.

    Science.gov (United States)

    Srividhya, M; Preethi, S; Gnanamani, A; Reddy, B S R

    2006-12-01

    Amphiphilic comb like macromonomer containing hydrophilic poly(ethylene glycol) groups covalently linked to poly(hydromethyl siloxane) (PHMS) were prepared by hydrosilylation reaction. The epoxy reacting sites were introduced to this amphiphilic system by the reaction with allyl epoxy propyl ether (AEPE). Bovine serum albumin (BSA), a model protein drug was loaded to the PEG-PDMS system and very thin membranes were made from this macromonomer adopting solution casting technique. The in vitro protein release studies at various pH conditions showed a controlled release profile without exhibiting any initial burst. The control of the initial burst might be due to the strong linkages of the protein with the membrane and the aggregation of the protein at the surface. The morphology of the membrane before and after the protein release, and the mechanical strength were evaluated. The surface properties of the membrane were studied using the contact angle measurements. PMID:16930885

  4. Screening Nylon-3 Polymers, a New Class of Cationic Amphiphiles, for siRNA Delivery

    OpenAIRE

    Nadithe, Venkatareddy; Liu, Runhui; Killinger, Bryan A.; Movassaghian, Sara; Kim, Na Hyung; Moszczynska, Anna B.; Masters, Kristyn S.; Gellman, Samuel H.; Merkel, Olivia M

    2014-01-01

    Amphiphilic nucleic acid carriers have attracted strong interest. Three groups of nylon-3 copolymers (poly-β-peptides) possessing different cationic/hydrophobic content were evaluated as siRNA delivery agents in this study. Their ability to condense siRNA was determined in SYBR Gold assays. Their cytotoxicity was tested by MTT assays, their efficiency of delivering Alexa Fluor-488-labeled siRNA intracellularly in the presence and absence of uptake inhibitors was assessed by flow cytometry, an...

  5. CONTROLLED SYNTHESIS OF AMPHIPHILIC BLOCK POLYMERS HAVING GLUCOSE RESIDUES AND THEIR STRUCTURE FORMATION

    Institute of Scientific and Technical Information of China (English)

    Takeaki Miyamoto; Masahiko Minoda; Yoshinobu Tsujii

    1999-01-01

    Vinyl ether (VE)-based amphiphilic block copolymers with D-glucose residues as hydrophilic pendants were synthesized by CH3CH(OiBu)Cl/ZnI2-initiated sequential living cationic copolymerization of 3-O-(vinyloxy)ethyl-1, 2:5, 6-di-O-isopropylidene-D-glucofuranose (IGVE) and isobutyl VE (IBVE) and subsequent deprotection. The precursor block copolymers had a narrow molecular weight distribution(Mw/Mn~1.1) and a controlled segmental composition. The solubility characteristics of the amphiphilic copolymer depended strongly on composition. Their solvent-cast thin films were examined, under a transmission electron microscope, and could be seen to exhibit various microphase-separated surface morphologies such as spheres, cylinders, and lamellae, depending on composition. The amphiphilic copolymers with the appropriate segmental composition were found to form a stable monolayer at the airwater interface, which was successfully transferred onto a substrate by the Langmuir-Blodgett (LB)technique. The layered structure of the built-up LB films was controlled by blending the homopolymer.

  6. Self-assembly of CdTe nanocrystals at the water/oil interface by amphiphilic hyperbranched polymers

    International Nuclear Information System (INIS)

    A general strategy for realizing the self-assembly of aqueous CdTe nanocrystals (NCs) at the water/oil interface by means of an amphiphilic core-shell hyperbranched polymer has been proposed. Aqueous CdTe NCs were firstly transferred into the chloroform phase in the presence of palmityl chloride functionalized hyperbranched poly(amidoamine) (HPAMAM-PC), and then self-assembled at the water/chloroform interface by decreasing the pH value of the aqueous phase or introducing α-CDs to the aqueous phase. The resulting CdTe/HPAMAM-PC self-assembly film was characterized by fluorescence microscopy, UV-vis, PL, TEM, EDS, FT-IR, DSC and TGA.

  7. Molecular Differentiated Initiator Reactivity in the Synthesis of Poly(caprolactone-Based Hydrophobic Homopolymer and Amphiphilic Core Corona Star Polymers

    Directory of Open Access Journals (Sweden)

    Eileen Deng

    2015-11-01

    Full Text Available Macromolecules that possess three-dimensional, branched molecular structures are of great interest because they exhibit significantly differentiated application performance compared to conventional linear (straight chain polymers. This paper reports the synthesis of 3- and 4-arm star branched polymers via ring opening polymerisation (ROP utilising multi-functional hydroxyl initiators and Sn(Oct2 as precatalyst. The structures produced include mono-functional hydrophobic and multi-functional amphiphilic core corona stars. The characteristics of the synthetic process were shown to be principally dependent upon the physical/dielectric properties of the initiators used. ROP’s using initiators that were more available to become directly involved with the Sn(Oct2 in the “in-situ” formation of the true catalytic species were observed to require shorter reaction times. Use of microwave heating (MWH in homopolymer star synthesis reduced reaction times compared to conventional heating (CH equivalents, this was attributed to an increased rate of “in-situ” catalyst formation. However, in amphiphilic core corona star formation, the MWH polymerisations exhibited slower propagation rates than CH equivalents. This was attributed to macro-structuring within the reaction medium, which reduced the potential for reaction. It was concluded that CH experiments were less affected by this macro-structuring because it was disrupted by the thermal currents/gradients caused by the conductive/convective heating mechanisms. These gradients are much reduced/absent with MWH because it selectively heats specific species simultaneously throughout the entire volume of the reaction medium. These partitioning problems were overcome by introducing additional quantities of the species that had been determined to selectively heat.

  8. Polymer micelles with hydrophobic core and ionic amphiphilic corona. 1. Statistical distribution of charged and nonpolar units in corona.

    Science.gov (United States)

    Lysenko, Evgeny A; Kulebyakina, Alevtina I; Chelushkin, Pavel S; Rumyantsev, Artem M; Kramarenko, Elena Yu; Zezin, Alexander B

    2012-12-11

    Polymer micelles with hydrophobic polystyrene (PS) core and ionic amphiphilic corona from charged N-ethyl-4-vinylpyridinium bromide (EVP) and uncharged 4-vinylpyridine (4VP) units spontaneously self-assembled from PS-block-poly(4VP-stat-EVP) macromolecules in mixed dimethylformamide/methanol/water solvent. The fraction of statistically distributed EVP units in corona-forming block is β = [EVP]/([EVP]+[4VP]) = 0.3-1. Micelles were transferred into water via dialysis technique, and pH was adjusted to 9, where 4VP is insoluble. Structural characteristics of micelles were investigated both experimentally and theoretically as a function of corona composition β. Methods of dynamic and static light scattering, electrophoretic mobility measurements, sedimentation velocity, transmission electron microscopy, and UV spectrophotometry were applied. All micelles possessed spherical morphology. The aggregation number, structure, and electrophoretic mobility of micelles changed in a jumplike manner near β ~ 0.6-0.75. Below and above this region, micelle characteristics were constant or insignificantly changed upon β. Theoretical dependencies for micelle aggregation number, corona dimensions, and fraction of small counterions outside corona versus β were derived via minimization the micelle free energy, taking into account surface, volume, electrostatic, and elastic contributions of chain units and translational entropy of mobile counterions. Theoretical estimations also point onto a sharp structural transition at a certain corona composition. The abrupt reorganization of micelle structure at β ~ 0.6-0.75 entails dramatic changes in micelle dispersion stability in the presence of NaCl or in the presence of oppositely charged polymeric (sodium polymethacrylate) or amphiphilic (sodium dodecyl sulfate) complexing agents.

  9. Use of hybrid composite particles prepared using alkoxysilane-functionalized amphiphilic polymer precursors for simultaneous removal of various pollutants from water.

    Science.gov (United States)

    Cho, Seulki; Kim, Nahae; Lee, Soonjae; Lee, Hoseok; Lee, Sang-Hyup; Kim, Juyoung; Choi, Jae-Woo

    2016-08-01

    In this study, we present new inorganic-organic hybrid particles and their possible application as an adsorbent for simultaneous removal of hydrophobic and hydrophilic pollutants from water. These hybrid particles were prepared using tailor-made alkoxysilane-functionalized amphiphilic polymer precursors (M-APAS), which have amphiphilic polymers and reactive alkoxysilane groups attached to the same backbone. Through a single conventional sol-gel process, the polymerization of M-APAS and the chemical conjugation of M-APAS onto silica nanoparticles was simultaneous, resulting in the formation of hybrid particles (M-APAS-SiO2) comprised of hyperbranch-like amphiphilic polymers bonded onto silica nanoparticles with a relatively high grafting efficiency. A test for the adsorption of water-soluble dye (organe-16) and water insoluble dye (solvent blue-35) onto the hybrid particles was performed to evaluate the possibility of adsorbing hydrophilic and hydrophobic compound within the same particle. The hybrid particle was also evaluated as an adsorbent for the removal of contaminated water containing various pollutants by wastewater treatment test. The hybrid particle could remove phenolic compounds from wastewater and the azo dye reactive orange-16 from aqueous solutions, and it was easily separated from the treated wastewater because of the different densities involved. These results demonstrate that the hybrid particles are a promising sorbent for hydrophilic and/or hydrophobic pollutants in water. PMID:27179430

  10. Effects of amphiphilic chitosan-g-poly(ε-caprolactone) polymer additives on paclitaxel release from drug eluting implants

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Weibin [Department of General Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092 (China); Gu, Chunhua [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Jiang, Han [Department of General Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092 (China); Zhang, Mengru [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Lang, Meidong, E-mail: mdlang@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2014-12-01

    Bioresorbable polymer stents have been proposed as promising medical implants to avoid long-term safety concerns and other potential issues caused by traditional materials. As an important member, poly(ε-caprolactone) (PCL) was used as the implant matrix with different drug loadings. To better regulate drug release rate, the hydrophilicity of PCL was adjusted by addition of amphiphilic graft copolymers, chitosan-g-poly(ε-caprolactone) (CP). The in vitro release results indicated that the improvement of bulk hydrophilicity could accelerate drug release better than that of surface coating. The optimum additive amount was 25% with CP9. Further study showed that the effect of aspirin molecules displayed no obvious difference to that of CP macromolecules on drug release rate. Moreover, these release profiles were fitted with mathematical models. The similarities were evaluated with similarity factors. Scanning electron microscopy (SEM) images displayed surface/cross-section morphologies of pure PCL and modified implants before and after release. - Highlights: • The improvement of bulk hydrophilicity better accelerated drug release. • The higher weight ratio of CP implants had, the faster the drug released. • The shorter PCL chain in CP graft coploymers, the faster the drug released. • The optimum additive amount was 25% with CP9. • Drug release profile conformed to controllable Fick diffusional release mechanism.

  11. Effects of amphiphilic chitosan-g-poly(ε-caprolactone) polymer additives on paclitaxel release from drug eluting implants

    International Nuclear Information System (INIS)

    Bioresorbable polymer stents have been proposed as promising medical implants to avoid long-term safety concerns and other potential issues caused by traditional materials. As an important member, poly(ε-caprolactone) (PCL) was used as the implant matrix with different drug loadings. To better regulate drug release rate, the hydrophilicity of PCL was adjusted by addition of amphiphilic graft copolymers, chitosan-g-poly(ε-caprolactone) (CP). The in vitro release results indicated that the improvement of bulk hydrophilicity could accelerate drug release better than that of surface coating. The optimum additive amount was 25% with CP9. Further study showed that the effect of aspirin molecules displayed no obvious difference to that of CP macromolecules on drug release rate. Moreover, these release profiles were fitted with mathematical models. The similarities were evaluated with similarity factors. Scanning electron microscopy (SEM) images displayed surface/cross-section morphologies of pure PCL and modified implants before and after release. - Highlights: • The improvement of bulk hydrophilicity better accelerated drug release. • The higher weight ratio of CP implants had, the faster the drug released. • The shorter PCL chain in CP graft coploymers, the faster the drug released. • The optimum additive amount was 25% with CP9. • Drug release profile conformed to controllable Fick diffusional release mechanism

  12. Reversible pH Stimulus-Response Material Based on Amphiphilic Block Polymer Self-Assembly and Its Electrochemical Application

    Directory of Open Access Journals (Sweden)

    Tianyi Wang

    2016-06-01

    Full Text Available Stimulus-responsive microporous solid thin films were successfully fabricated by simple molecular self-assembly via an amphiphilic block polymer, polystryene–b–polyacrylic acid (PS–b–PAA. The solid thin films exhibit different surface morphologies in response to external stimuli, such as environments with different pH values in aqueous solutions. The experiments have successfully applied atomic force microscope (AFM technology to observe in-situ surface morphological changes. There is a reversible evolution of the microstructures in buffer solutions over a pH range of 2.4–9.2. These observations have been explained by positing that there is no conventional PAA swelling but that the PAA chains in the micropores stretch and contract with changes in the pH of the solution environment. The hydrophobicity of the solid thin film surface was transformed into super-hydrophilicity, as captured by optical contact angle measurements. The stimulus-responsive dynamics of pore sizes was described by a two-stage mechanism. A promising electrochemical application of this film is suggested via combination with an electrochemical impedance technique. This study is aimed at strategies for the functionalization of stimulus-responsive microporous solid thin films with reversible tunable surface morphologies, and exploring new smart materials with switch-on/switch-off behavior.

  13. Synthesis, Characterization, and Evaluation of a Novel Amphiphilic Polymer RGD-PEG-Chol for Target Drug Delivery System

    Directory of Open Access Journals (Sweden)

    Shi Zeng

    2014-01-01

    Full Text Available An amphiphilic polymer RGD-PEG-Chol which can be produced in large scale at a very low cost has been synthesized successfully. The synthesized intermediates and final products were characterized and confirmed by 1H nuclear magnetic resonance spectrum (1H NMR and Fourier transform infrared spectrum (FT-IR. The paclitaxel- (PTX- loaded liposomes based on RGD-PEG-Chol were then prepared by film formation method. The liposomes had a size within 100 nm and significantly enhanced the cytotoxicity of paclitaxel to B16F10 cell as demonstrated by MTT test (IC50 = 0.079 μg/mL of RGD-modified PTX-loaded liposomes compared to 9.57 μg/mL of free PTX. Flow cytometry analysis revealed that the cellular uptake of coumarin encapsulated in the RGD-PEG-Chol modified liposome was increased for HUVEC cells. This work provides a reasonable, facile, and economic approach to prepare peptide-modified liposome materials with controllable performances and the obtained linear RGD-modified PTX-loaded liposomes might be attractive as a drug delivery system.

  14. Unlocking Chain Exchange in Highly Amphiphilic Block Polymer Micellar Systems: Influence of Agitation

    OpenAIRE

    Murphy, Ryan P.; Kelley, Elizabeth G.; Rogers, Simon A.; Sullivan, Millicent O.; Epps, Thomas H.

    2014-01-01

    Chain exchange between block polymer micelles in highly selective solvents, such as water, is well-known to be arrested under quiescent conditions, yet this work demonstrates that simple agitation methods can induce rapid chain exchange in these solvents. Aqueous solutions containing either pure poly(butadiene-b-ethylene oxide) or pure poly(butadiene-b-ethylene oxide-d 4) micelles were combined and then subjected to agitation by vortex mixing, concentric cylinder Couette flow, or nitrogen gas...

  15. Hydrophobically modified inulin as an amphiphilic carbohydrate polymer for micellar delivery of paclitaxel for intravenous route.

    Science.gov (United States)

    Muley, Pratik; Kumar, Sunny; El Kourati, Fadoua; Kesharwani, Siddharth S; Tummala, Hemachand

    2016-03-16

    Micellization offers several advantages for the delivery of water insoluble drugs including a nanoparticulate 'core-shell' delivery system for drug targeting. Recently, hydrophobically modified polysaccharides (HMPs) are gaining recognition as micelle forming polymers to encapsulate hydrophobic drugs. In this manuscript, for the first time, we have evaluated the self-assembling properties of a lauryl carbamate derivative of the poly-fructose natural polymer inulin (Inutec SP1(®) (INT)) to form paclitaxel (PTX) loaded micelles. INT self-assembled into well-defined micellar structures in aqueous environment with a low critical micellar concentration of 27.8 μg/ml. INT micelles exhibited excellent hemocompatibility and low toxicity to cultured cells. PTX loaded INT micelles exhibited a mean size of 256.37 ± 10.45 nm with excellent drug encapsulation efficiency (95.66 ± 2.25%) and loading (8.69 ± 0.22%). PTX loaded micelles also displayed sustained release of PTX and enhanced anti-cancer efficacy in-vitro in mouse melanoma cells (B16F10) compared to Taxol formulation with Cremophor EL as solvent. In addition, PTX loaded INT micelles exhibited comparable in-vivo antitumor activity in B16F10 allograft mouse model at half the dose of Taxol. In conclusion, INT offers safe, inexpensive and natural alternative to widely used PEG-modified polymers for the formulation of micellar delivery systems for paclitaxel.

  16. Phospholipid-polymer amphiphile hybrid assemblies and their interaction with macrophages.

    Science.gov (United States)

    Panneerselvam, Karthiga; Lynge, Martin E; Riber, Camilla Frich; Mena-Hernando, Sofia; Smith, Anton A A; Goldie, Kenneth N; Zelikin, Alexander N; Städler, Brigitte

    2015-09-01

    Recently, the combination of lipids and block copolymers has become an alternative to liposomes and polymersomes as nano-sized drug carriers. We synthesize novel block copolymers consisting of poly(cholesteryl acrylate) as the hydrophobic core and poly(N-isopropylacrylamide) (PNIPAAm) as the hydrophilic extensions. Their successful phospholipid-assisted assembly into vesicles is demonstrated using the evaporation-hydration method. The preserved thermo-responsive property of the lipid-polymer hybrids is shown by a temperature dependent adsorption behaviour of the vesicles to poly(l lysine) coated surfaces. As expected, the vesicle adsorption is found to be higher at elevated temperatures. The cellular uptake efficiency of hybrids is assessed using macrophages with applied shear stress. The amount of adhering macrophages is affected by the time and level of applied shear stress. Further, it is found that shorter PNIPAAm extensions lead to higher uptake of the assemblies by the macrophages with applied shear stress. No inherent cytotoxicity is observed at the tested conditions. Taken together, this first example of responsive lipid-polymer hybrids, and their positive biological evaluation makes them promising nano-sized drug carrier candidates. PMID:26339330

  17. Strain Measurement Using Embedded Fiber Bragg Grating Sensors Inside an Anchored Carbon Fiber Polymer Reinforcement Prestressing Rod for Structural Monitoring

    DEFF Research Database (Denmark)

    Kerrouche, Abdelfateh; Boyle, William J.O.; Sun, Tong;

    2009-01-01

    Results are reported from a study carried out using a series of Bragg grating based optical fiber sensors written into a very short length (60mm) optical fiber net work and integrated into carbon fiber polymer reinforcement (CFPR) rod. Such rods are used as reinforcements in concrete structures...... from the calibrated force applied by the pulling machine and from a conventional resistive strain gauge mounted on the rod itself is obtained. Calculations from strain to shear stress show a relatively uniform stress distribution along the bar anchor used. The results give confidence to results from...

  18. Neutron reflectivity of supported membranes incorporating terminally anchored polymers: Protrusions vs. blisters

    DEFF Research Database (Denmark)

    Fragneto, Giovanna; Halperin, Avraham; Klösgen-Buchkremer, Beate Maria;

    2013-01-01

    The effect of terminally anchored chains on the structure of lipid bilayers adsorbed at the solid/water interface was characterized by neutron reflectivity. In the studied system, the inner leaflet, closer to the substrate, consisted of head-deuterated 1,2-distearoyl-sn-glycero-3-phosphorylcholin...

  19. Interfacial Rheology of Hydrogen-Bonded Polymer Multilayers Assembled at Liquid Interfaces: Influence of Anchoring Energy and Hydrophobic Interactions.

    Science.gov (United States)

    Le Tirilly, Sandrine; Tregouët, Corentin; Reyssat, Mathilde; Bône, Stéphane; Geffroy, Cédric; Fuller, Gerald; Pantoustier, Nadège; Perrin, Patrick; Monteux, Cécile

    2016-06-21

    We study the 2D rheological properties of hydrogen-bonded polymer multilayers assembled directly at dodecane-water and air-water interfaces using pendant drop/bubble dilation and the double-wall ring method for interfacial shear. We use poly(vinylpyrrolidone) (PVP) as a proton acceptor and a series of polyacrylic acids as proton donors. The PAA series of chains with varying hydrophobicity was fashioned from poly(acrylic acid), (PAA), polymethacrylic acid (PMAA), and a homemade hydrophobically modified polymer. The latter consisted of a PAA backbone covalently grafted with C12 moieties at 1% mol (referred to as PAA-1C12). Replacing PAA with the more hydrophobic PMAA provides a route for combining hydrogen bonding and hydrophobic interactions to increase the strength and/or the number of links connecting the polyacid chains to PVP. This systematic replacement allows for control of the ability of the monomer units inside the absorbed polymer layer to reorganize as the interface is sheared or compressed. Consequently, the interplay of hydrogen bonding and hydrophobic interactions leads to control of the resistance of the polymer multilayers to both shear and dilation. Using PAA-1C12 as the first layer improves the anchoring energy of a few monomers of the chain without changing the strength of the monomer-monomer contact in the complex layer. In this way, the layer does not resist shear but resists compression. This strategy provides the means for using hydrophobicity to control the interfacial dynamics of the complexes adsorbed at the interface of the bubbles and droplets that either elongate or buckle upon compression. Moreover, we demonstrate the pH responsiveness of these interfacial multilayers by adding aliquots of NaOH to the acidic water subphase surrounding the bubbles and droplets. Subsequent pH changes can eventually break the polymer complex, providing opportunities for encapsulation/release applications. PMID:27176147

  20. Amphiphilic dendronized homopolymers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of second generation of amphiphilic dendronized homopolymers are efficiently synthesized,and their thermoresponsiveness in aqueous solutions and secondary structures in methanol solutions are described.These polymers are constructed in each repeat unit with various generations of hydrophobic 4-aminoproline and hydrophilic oligoethylene glycol (OEG)-based dendrons,and their over-all hydrophilicity is tuned by varying these dendron generations.Polymers with or without the first generation of proline dendron show good water solubility at room temperature,but exhibit typical thermoresponsive behaviors at elevated temperatures as characterized by turbidity measurements using UV-vis spectroscopy,while the polymer with the secondary generation of proline dendron is not soluble in water.All polymers show ordered secondary structures as evidenced by the optical rotation and circular dichroism experiments.Finally,assembly of these amphiphilic homopolymers into porous films via breath figure (BF) technique is described,and polymer structures are found to show significant influence on the morphology of porous film.

  1. Preparation of pH-sensitive amphiphilic block star polymers, their self-assembling characteristics and release behavior on encapsulated molecules

    KAUST Repository

    Song, Xiaowan

    2016-05-28

    Poly(ethylene glycol) (PEG), a polymer with excellent biocompatibility, was widely used to form nanoparticles for drug delivery applications. In this paper, based on PEG, a series of pH-sensitive amphiphilic block star polymers of poly(ethylene glycol)-block-poly(ethoxy ethyl glycidyl ether) (PEG-b-PEEGE) with different hydrophobic length were synthesized by living anionic ring-opening polymerization method. The products were characterized using 1H NMR and gel permeation chromatography. These copolymers could self-assemble in aqueous solution to form micellar structure with controlled morphologies. Transmission electron microscopy showed that the nanoparticles are spherical or rodlike with different hydrophilic mass fractions. The pH response of polymeric aggregates from PEG-b-PEEGE was detected by fluorescence probe technique at different pH. A pH-dependent release behavior was observed and pH-responsiveness of PEG-b-PEEGE was affected by the hydrophobic block length. These results demonstrated that star-shaped polymers (PEG-b-PEEGE) are attractive candidates as anticancer drug delivery carriers. © 2016 Springer-Verlag Berlin Heidelberg

  2. Nonlinear viscoelasticity of freestanding and polymer-anchored vertically aligned carbon nanotube foams

    Science.gov (United States)

    Lattanzi, Ludovica; Raney, Jordan R.; De Nardo, Luigi; Misra, Abha; Daraio, Chiara

    2012-04-01

    Vertical arrays of carbon nanotubes (VACNTs) show unique mechanical behavior in compression, with a highly nonlinear response similar to that of open cell foams and the ability to recover large deformations. Here, we study the viscoelastic response of both freestanding VACNT arrays and sandwich structures composed of a VACNT array partially embedded between two layers of poly(dimethylsiloxane) (PDMS) and bucky paper. The VACNTs tested are ˜2 mm thick foams grown via an injection chemical vapor deposition method. Both freestanding and sandwich structures exhibit a time-dependent behavior under compression. A power-law function of time is used to describe the main features observed in creep and stress-relaxation tests. The power-law exponents show nonlinear viscoelastic behavior in which the rate of creep is dependent upon the stress level and the rate of stress relaxation is dependent upon the strain level. The results show a marginal effect of the thin PDMS/bucky paper layers on the viscoelastic responses. At high strain levels (ɛ = 0.8), the peak stress for the anchored CNTs reaches ˜45 MPa, whereas it is only ˜15 MPa for freestanding CNTs, suggesting a large effect of PDMS on the structural response of the sandwich structures.

  3. Bio-inspired Construction of Advanced Fuel Cell Cathode with Pt Anchored in Ordered Hybrid Polymer Matrix

    Science.gov (United States)

    Xia, Zhangxun; Wang, Suli; Jiang, Luhua; Sun, Hai; Liu, Shuang; Fu, Xudong; Zhang, Bingsen; Sheng Su, Dang; Wang, Jianqiang; Sun, Gongquan

    2015-11-01

    The significant use of platinum for catalyzing the cathodic oxygen reduction reactions (ORRs) has hampered the widespread use of polymer electrolyte membrane fuel cells (PEMFCs). The construction of well-defined electrode architecture in nanoscale with enhanced utilization and catalytic performance of Pt might be a promising approach to address such barrier. Inspired by the highly efficient catalytic processes in enzymes with active centers embedded in charge transport pathways, here we demonstrate for the first time a design that allocates platinum nanoparticles (Pt NPs) at the boundaries with dual-functions of conducting both electrons by aid of polypyrrole and protons via Nafion® ionomer within hierarchical nanoarrays. By mimicking enzymes functionally, an impressive ORR activity and stability is achieved. Using this brand new electrode architecture as the cathode and the anode of a PEMFC, a high mass specific power density of 5.23 W mg-1Pt is achieved, with remarkable durability. These improvements are ascribed to not only the electron decoration and the anchoring effects from the Nafion® ionomer decorated PPy substrate to the supported Pt NPs, but also the fast charge and mass transport facilitated by the electron and proton pathways within the electrode architecture.

  4. Synthesis and In Vitro Cancer Cell Targeting of Folate-Functionalized Biodegradable Amphiphilic Dendrimer-Like Star Polymers

    NARCIS (Netherlands)

    Cao, Weiqiang; Zhou, Jing; Wang, Yong; Zhu, Lei

    2010-01-01

    By coupling a well-defined PLLA star polymer with six carboxylic acid-terminated polyester dendrons based on 2,2-bis(hydroxymethyl)propionic acid, a biodegradable dendrimer-like star polymer (DLSP) with multiple carboxylic acid groups at the outer surface was successfully synthesized. Conjugation of

  5. The study of static adsorption of the amphiphilic polymer on rocks and minerals%两亲聚合物在岩石矿物上的静态吸附研究

    Institute of Scientific and Technical Information of China (English)

    康万利; 张磊; 孟令伟; 彭孙宇

    2012-01-01

    The static adsorption of different concentrations of amphiphilic polymer on rocks and minerals is studied by starch-cadmium iodide colorimetric method and the influence of adsorption rules by salinity, temperature and surfactant are discussed. The results showed that the adsorption isotherm of the amphiphi-lic polymer are combined by L style, and H style, having a maximum adsorption peak and showing the characteristics of multilayer adsorption. For different rocks and minerals,the adsorption of amphiphilic pol-ymer on clay (Γmax =11.5 mg/g) is higher than kaolin (Γmax = 10 mg/g) and silica sand (Γmax= 0. 28 mg/g) ;the amount of adsorption of the amphiphilic polymer first decreases slightly and then increa-ses with salinity increasing, and increases with temperature increasing; and surfactant can lead to the de-crease of the original adsorption of amphiphilic polymer.%利用淀粉-碘化镉比色法测定了不同浓度两亲聚合物AP在岩石矿物上的静态吸附量,探讨了矿化度、温度和表面活性剂对其吸附的影响.结果表明,两亲聚合物的吸附等温线由L型和H型构成,存在一个最高吸附峰,具有多层吸附的特征;对于不同岩石矿物,两亲聚合物吸附量大小次序为粘土(Γmax为11.5 mg/g)>高岭土(Γmax为10 mg/g)>石英砂(Γmax为0.28 mg/g);两亲聚合物的吸附量随矿化度的增加先略微降低后又增大,随温度的升高增加;表面活性剂可降低两亲聚合物的吸附量.

  6. Polymer Physics Prize Lecture: Self-assemblies of Giant Molecular Shape Amphiphiles as a New Platform for Engineering Structures with Sub-Nanometer Feature Sizes

    Science.gov (United States)

    Cheng, Stephen Z. D.

    2013-03-01

    Utilizing nano-building blocks rather than atoms to construct and engineer new structures is a fresh approach to design and develop functional materials for the purpose of transferring and amplifying microscopic functionality to macroscopic materials' property. As one of the important elements of these nano-building blocks, giant molecular shape amphiphiles (GMSAs) provide a latest platform for generating self-assembled ordered structures at nanometer scale, which are stabilized by collective physical bonds (such as collective hydrogen bonding). In this talk, two topics will be focused on. First, composed of functionalized hydrophilic molecular nanoparticles as the heads with rigid shape and fixed volume, and tethered polymer chains as the tails (such as giant molecular surfactants and lipids and other topologies), these GMSAs of various architectures can self-assemble into highly diversified, thermodynamically stable microstructures at sub-10 nm length scale in the bulk, thin film and solution states. Second, GMSAs could also be constructed solely from nanoparticles interconnected via different numbers of the rigid linkages in specific symmetry, simulating the overall shapes of small molecules but with sizes that are one-order of magnitude larger in length and three-order of magnitude larger in volume. Giant crystal structures can then be obtained from this class of ``giant molecules'' via supramolecular crystallization. These findings are not only scientifically intriguing in understanding the physical principles underlying their self-assembly, but also technologically relevant in industrial applications.

  7. Amphiphilic Soft Janus Particles as Interfacial Stabilizers

    Science.gov (United States)

    Wang, Wenda; Niu, Sunny; Sosa, Chris; Prud'Homme, Robert; Priestley, Rodney; Priestley Polymer group Team; Prud'homme Research Group Team

    Janus particles, which incorporate two or more ``faces'' with different chemical functionality, have attracted great attention in scientific research. Amphiphilic Janus particles have two faces with distinctly different hydrophobicity. This can be thought of as colloidal surfactants. Theoretical studies on the stabilization of emulsions using Janus particles have confirmed higher efficiency. Herein we synthesize the narrow distributed amphiphilic polymeric Janus particles via Precipitation-Induced Self-Assembly (PISA). The efficiency of the amphiphilic Janus particles are tested on different oil/water systems. Biocompatible polymers can also be used on this strategy and may potentially have wide application for food emulsion, cosmetics and personal products.

  8. Facile Determination of Molecular Structure Trends in Amphiphilic Core Corona Star Polymer Synthesis via Dielectric Property Measurement.

    Science.gov (United States)

    Hild, Frederic; Nguyen, Nam T; Deng, Eileen; Katrib, Juliano; Dimitrakis, Georgios; Lau, Phei-Li; Irvine, Derek J

    2016-08-01

    The use of dielectric property measurements to define specific trends in the molecular structures of poly(caprolactone) containing star polymers and/or the interbatch repeatability of the synthetic procedures used to generate them is demonstrated. The magnitude of the dielectric property value is shown to accurately reflect: (a) the number of functional groups within a series of materials with similar molecular size when no additional intermolecular order is present in the medium, (b) the polymer molecular size for a series of materials containing a fixed core material and so functional group number, and/or (c) the batch to batch repeatability of the synthesis method. The dielectric measurements are validated by comparison to spectroscopic/chromatographic data. PMID:27315130

  9. Facile Determination of Molecular Structure Trends in Amphiphilic Core Corona Star Polymer Synthesis via Dielectric Property Measurement.

    Science.gov (United States)

    Hild, Frederic; Nguyen, Nam T; Deng, Eileen; Katrib, Juliano; Dimitrakis, Georgios; Lau, Phei-Li; Irvine, Derek J

    2016-08-01

    The use of dielectric property measurements to define specific trends in the molecular structures of poly(caprolactone) containing star polymers and/or the interbatch repeatability of the synthetic procedures used to generate them is demonstrated. The magnitude of the dielectric property value is shown to accurately reflect: (a) the number of functional groups within a series of materials with similar molecular size when no additional intermolecular order is present in the medium, (b) the polymer molecular size for a series of materials containing a fixed core material and so functional group number, and/or (c) the batch to batch repeatability of the synthesis method. The dielectric measurements are validated by comparison to spectroscopic/chromatographic data.

  10. Relationship between Surface Properties and In Vitro Drug Release from a Compressed Matrix Containing an Amphiphilic Polymer Material.

    Science.gov (United States)

    Yarce, Cristhian J; Pineda, Diego; Correa, Clara E; Salamanca, Constain H

    2016-01-01

    The performance of compressed tablet drug delivery systems made using polymeric materials depend on multiple factors, such as surface properties like contact angle, surface free energy and water absorption rate, besides the release mechanisms driven by the kind of polymer used. Hence, it should be possible to establish a relationship between the surface properties and the drug release kinetics. Compressed tablets with different proportions of poly(maleic acid-alt-octadecene) potassium salt (0%, 10%, 20%, 30% and 40%) were prepared. Blends of a model drug (ampicillin trihydrate) and the polymer material were analyzed by DSC. The surface properties of the tablets were determined by the sessile drop method, while the surface energy was determined using the semi-empirical Young-Dupre, Neumann and OWRK models. The release profiles were determined simulating in vitro conditions (buffer solutions pH 1.2 and pH 7.4 with ionic strength of 1.5 M at 37 °C (310.15 K)). A kinetic analysis of the dissolution profiles using different models (zero order, first order, Higuchi and Korsmeyer-Peppas) was realized. The results showed a significant effect of the proportion of polymer in both the surface properties of the tablets and the dissolution release, indicating a relationship between the kinetic and thermodynamic properties. PMID:27347979

  11. Polymersomes via Self-Assembly of Amphiphilic β-Cyclodextrin-Centered Triarm Star Polymers for Enhanced Oral Bioavailability of Water-Soluble Chemotherapeutics.

    Science.gov (United States)

    Hu, Mengying; Shen, Yurun; Zhang, Lu; Qiu, Liyan

    2016-03-14

    To date, improving oral bioavailability of water-soluble drugs with poor membrane permeability is still challenging. An example of this includes doxorubicin hydrochloride (DOX·HCl), a widely used chemotherapeutic. We therefore developed a novel DOX·HCl-loaded polymersome (Ps-DOX·HCl) self-assembled by amphiphilic β-cyclodextrin-centered triarm star polymer (mPEG(2k)-PLA(3k))3-CD with the considerable drug loading capability. Using Madin-Darby canine kidney (MDCK) cells trans-well models, it was found that the cellular uptake and absorptive transport of DOX·HCl was significantly increased and the efflux was attenuated when delivered through polymersomes than free drugs. This phenomenon was further verified in mechanistic studies, which was attributed to the change in membrane transport pathway from paracellular route (free DOX·HCl) to active transcellular transport (drug-loaded polymersomes). Moreover, in vivo pharmacokinetic studies in mice demonstrated a significant increase in the oral bioavailability of Ps-DOX·HCl compared with free DOX·HCl (7.32-fold), as well as extended half-life (8.22-fold). This resulted in a substantial anticancer efficacy against mouse sarcoma 180 (S180) tumor in vivo. The cardiotoxicity, which is intrinsically induced by DOX·HCl, and toxicity toward gastrointestinal tissues were avoided according to histological studies. These findings indicate that (mPEG(2k)-PLA(3k))3-CD copolymer displays great potential as a vehicle for the effective oral delivery of water-soluble drugs with low permeability. PMID:26840277

  12. A comparative study on the effects of amphiphilic and hydrophilic polymers on the release profiles of a poorly water-soluble drug.

    Science.gov (United States)

    Irwan, Anastasia W; Berania, Jacqueline E; Liu, Xueming

    2016-03-01

    This paper reports the use of two crystalline polymers, an amphiphilic Pluronic® F-127 (PF-127) and a hydrophilic poly(ethylene glycol) (PEG6000) as drug delivery carriers for improving the drug release of a poorly water-soluble drug, fenofibrate (FEN), via micelle formation and formation of a solid dispersion (SD). In 10% PF-127 (aq.), FEN showed an equilibrium solubility of ca. 0.6 mg/mL, due to micelle formation. In contrast, in 10% PEG6000 (aq.), FEN only exhibited an equilibrium solubility of 0.0037 mg/mL. FEN-loaded micelles in PF-127 were prepared by direct dissolution and membrane dialysis. Both methods only yielded a highest drug loading (DL) of 0.5%. SDs of FEN in PF-127 and PEG6000, at DLs of 5-80%, were prepared by solvent evaporation. In-vitro dissolution testing showed that both micelles and SDs significantly improved FEN's release rate. The SDs of FEN in PF-127 showed significantly faster release than crystalline FEN, when the DL was as high as 50%, whereas SDs of PEG6000 showed similar enhancement in the release rate when the DL was not more than 20%. The DSC thermograms of SDs of PF-127 exhibited a single phase transition peak at ca. 55-57 °C when the DL was not more than 50%, whereas those in PEG6000 exhibited a similar peak at ca. 61-63 °C when the DL was not more than 35%. When the DL exceeded 50% for SDs of PF-127 and 35% for SDs of PEG6000, DSC thermograms showed two melting peaks for the carrier polymer and FEN, respectively. FT-IR studies revealed that PF-127 has a stronger hydrophobic-hydrophobic interaction with FEN than PEG6000. It is likely that both dispersion and micelle formation contributed to the stronger effect of PF-127 on enhancing the release rate of FEN in its SDs. PMID:25496001

  13. A comparative study on the effects of amphiphilic and hydrophilic polymers on the release profiles of a poorly water-soluble drug.

    Science.gov (United States)

    Irwan, Anastasia W; Berania, Jacqueline E; Liu, Xueming

    2016-03-01

    This paper reports the use of two crystalline polymers, an amphiphilic Pluronic® F-127 (PF-127) and a hydrophilic poly(ethylene glycol) (PEG6000) as drug delivery carriers for improving the drug release of a poorly water-soluble drug, fenofibrate (FEN), via micelle formation and formation of a solid dispersion (SD). In 10% PF-127 (aq.), FEN showed an equilibrium solubility of ca. 0.6 mg/mL, due to micelle formation. In contrast, in 10% PEG6000 (aq.), FEN only exhibited an equilibrium solubility of 0.0037 mg/mL. FEN-loaded micelles in PF-127 were prepared by direct dissolution and membrane dialysis. Both methods only yielded a highest drug loading (DL) of 0.5%. SDs of FEN in PF-127 and PEG6000, at DLs of 5-80%, were prepared by solvent evaporation. In-vitro dissolution testing showed that both micelles and SDs significantly improved FEN's release rate. The SDs of FEN in PF-127 showed significantly faster release than crystalline FEN, when the DL was as high as 50%, whereas SDs of PEG6000 showed similar enhancement in the release rate when the DL was not more than 20%. The DSC thermograms of SDs of PF-127 exhibited a single phase transition peak at ca. 55-57 °C when the DL was not more than 50%, whereas those in PEG6000 exhibited a similar peak at ca. 61-63 °C when the DL was not more than 35%. When the DL exceeded 50% for SDs of PF-127 and 35% for SDs of PEG6000, DSC thermograms showed two melting peaks for the carrier polymer and FEN, respectively. FT-IR studies revealed that PF-127 has a stronger hydrophobic-hydrophobic interaction with FEN than PEG6000. It is likely that both dispersion and micelle formation contributed to the stronger effect of PF-127 on enhancing the release rate of FEN in its SDs.

  14. Anchor reinforcements

    Energy Technology Data Exchange (ETDEWEB)

    Levkovich, P.Ye.; Sal' nikov, V.K.; Savich, N.S.

    1980-11-30

    An anchor reinforcement includes an anchor shaft, an elastic jig with a separator wall having compartments placed parallely along it and filled with reinforcement material and a device for destroying the jig wall separator. To quickly put the anchor in place and increase the reliability of the reinforcement by mixing the reinforcement material components better, the device for destroying the jig separator wall was made in the shape of a shovel, fastened to the anchor shaft and the separator wall has a longitudinal hollow for holding the anchor shaft/shovel.

  15. Bioefficacy evaluation of controlled release formulations based on amphiphilic nano-polymer of carbofuran against Meloidogyne incognita infecting tomato.

    Science.gov (United States)

    Pankaj; Shakil, Najam Akhtar; Kumar, Jitendra; Singh, M K; Singh, Khajan

    2012-01-01

    In the present investigation, the bioefficacy of developed carbofuran formulations, with PEG-600 (7a, CP1) & PEG-900 (7b, CP2) @ 5, 10 and 20 ppm, along with commercial formulation of carbofuran 3G (CP0) were evaluated against the root-knot nematode, Meloidogyne incognita infecting tomato (cv. Pusa Ruby) in pot and field conditions. The bioefficacy data indicated that the formulations developed by utilizing polymers having PEG - 900 (7b) as hydrophilic segment were effective even at 14 days post inoculation (dpi) as evident from shoot and root length. Also, the reduction in penetration was found to be maximum with CP2 (3.6 - 4.6 J2s) at all concentrations compared to CP1 (6.6-16.4 J2s) and CP0 (29.3-32.6 J2s). Overall, CP2 was more effective in reducing the number of nematodes up to 14 days, compared to CP1 and CP0. Both the CR formulations (CP1 and CP2) in general significantly reduced the number of galls, when compared to CP0. However, under field conditions, lower concentrations (5, and 10 ppm) of CP2, were less effective in controlling the gall formation whereas, CP2 at 20 ppm, was most effective than other treatments. The study revealed that the developed CR formulations of carbofuran have the potential for effective management of M. incognita in tomato under field conditions.

  16. Influence of polymer size, liposomal composition, surface charge, and temperature on the permeability of pH-sensitive liposomes containing lipid-anchored poly(2-ethylacrylic acid

    Directory of Open Access Journals (Sweden)

    Lu T

    2012-09-01

    Full Text Available Tingli Lu,1 Zhao Wang,2 Yufan Ma,1 Yang Zhang,2 Tao Chen1,21Key Laboratory for Space Bioscience and Biotechnology, School of Life Science, Northwestern Polytechnical University, 2Liposome Research Centre, Xi'an, ChinaBackground: Liposomes containing pH-sensitive polymers are promising candidates for the treatment of tumors and localized infection. This study aimed to identify parameters influencing the extent of contents release from poly(ethylacrylic acid (PEAA vesicles, focusing on the effects of polymer size, lipid composition, vesicle surface charge, and temperature.Methods: Anchored lipid pH-sensitive PEAA was synthesized using PEAA with a molecular weight of 8.4 kDa. PEAA vesicles were prepared by insertion of the lipid-anchored PEAA into preformed large unilamellar vesicles. The preformed liposomes were manipulated by varying the phosphocholine and cholesterol content, and by adding negative or positive charges to the liposomes. A calcein release assay was used to evaluate the effects of polymer size, liposome composition, surface charge, and temperature on liposomal permeability.Results: The release efficiency of the calcein-entrapped vesicles was found to be dependent on the PEAA polymer size. PEAA vesicles containing a phosphatidylcholine to cholesterol ratio of 60:40 (mol/mol released more than 80% of their calcein content when the molecular weight of PEAA was larger than 8.4 kDa. Therefore, the same-sized polymer of 8.4 kDa was used for the rest of study. The calcein release potential was found to decrease as the percentage of cholesterol increased and with an increase in the phosphocholine acyl chain length (DMPC . DPPC . DSPC. Negatively charged and neutral vesicles released similar amounts of calcein, whereas positively charged liposomes released a significant amount of their contents. pH-sensitive release was dependent on temperature. Dramatic content release was observed at higher temperatures.Conclusion: The observed

  17. Perfluorinated Moieties Increase the Interaction of Amphiphilic Block Copolymers with Lipid Monolayers.

    Science.gov (United States)

    Schwieger, Christian; Blaffert, Jacob; Li, Zheng; Kressler, Jörg; Blume, Alfred

    2016-08-16

    The interaction of amphiphilic and triphilic block copolymers with lipid monolayers has been studied. Amphiphilic triblock copolymer PGMA20-PPO34-PGMA20 (GP) is composed of a hydrophobic poly(propylene oxide) (PPO) middle block that is flanked by two hydrophilic poly(glycerol monomethacrylate) (PGMA) side blocks. The attachment of a perfluoro-n-nonyl residue (F9) to either end of GP yields a triphilic polymer with the sequence F9-PGMA20-PPO34-PGMA20-F9 (F-GP). The F9 chains are fluorophilic, i.e., they have a tendency to demix in hydrophilic as well as in lipophilic environments. We investigated (i) the adsorption of both polymers to differently composed lipid monolayers and (ii) the compression behavior of mixed polymer/lipid monolayers. The lipid monolayers are composed of phospholipids with PC or PE headgroups and acyl chains of different length and saturation. Both polymers interact with lipid monolayers by inserting their hydrophobic moieties (PPO, F9). The interaction is markedly enhanced in the presence of F9 chains, which act as membrane anchors. GP inserts into lipid monolayers up to a surface pressure of 30 mN/m, whereas F-GP inserts into monolayers at up to 45 mN/m, suggesting that F-GP also inserts into lipid bilayer membranes. The adsorption of both polymers to lipid monolayers with short acyl chains is favored. Upon compression, a two-step squeeze-out of F-GP occurs, with PPO blocks being released into the aqueous subphase at 28 mN/m and the F9 chains being squeezed out at 48 mN/m. GP is squeezed out in one step at 28 mN/m because of the lack of F9 anchor groups. The liquid expanded (LE) to liquid condensed (LC) phase transition of DPPC and DMPE is maintained in the presence of the polymers, indicating that the polymers can be accommodated in LE- and LC-phase monolayers. These results show how fluorinated moieties can be included in the rational design of membrane-binding polymers. PMID:27442444

  18. Self-assembly of amphiphilic homopolymers bearing ferrocene and carboxyl functionalities: effect of polymer concentration, β-cyclodextrin, and length of alkyl linker.

    Science.gov (United States)

    Feng, Chun; Lu, Guolin; Li, Yongjun; Huang, Xiaoyu

    2013-08-27

    Three new acrylamide monomers containing ferrocene and tert-butyl ester groups were first synthesized via multistep nucleophilic substitution reaction under mild conditions followed by reversible addition-fragmentation chain transfer (RAFT) homopolymerization to give well-defined homopolymers with narrow molecular weight distributions (M(w)/M(n) ≤ 1.36). The target amphiphilic homopolymers were obtained by the acidic hydrolysis of tert-butyoxycarbonyls to carboxyls in every repeating unit using CF3COOH. The self-assembly behaviors of these amphiphilic homopolymers bearing both ferrocene and carboxyl moieties in each repeating unit in aqueous media were investigated by transmission emission microscopy (TEM), dynamic light scattering (DLS), and atomic force microscopy (AFM). Large compound micelles with different morphologies were formed by these amphiphilic homopolymers, which consist of the corona formed by hydrophilic carboxyls and the core containing numerous reverse micelles with hydrophilic islands of carboxyls in continuous hydrophobic phase of ferrocene-based segments. The morphologies of the formed micelles could be tuned by the concentration of amphiphilic homopolymers, pH value of the solution, the length of -CH2 linker between ferrocene group and carboxyl, and the amount of β-cyclodextrin (β-CD). PMID:23977901

  19. Amphiphile nanoarchitectonics: from basic physical chemistry to advanced applications.

    Science.gov (United States)

    Ramanathan, Muruganathan; Shrestha, Lok Kumar; Mori, Taizo; Ji, Qingmin; Hill, Jonathan P; Ariga, Katsuhiko

    2013-07-14

    Amphiphiles, either synthetic or natural, are structurally simple molecules with the unprecedented capacity to self-assemble into complex, hierarchical geometries in nanospace. Effective self-assembly processes of amphiphiles are often used to mimic biological systems, such as assembly of lipids and proteins, which has paved a way for bottom-up nanotechnology with bio-like advanced functions. Recent developments in nanostructure formation combine simple processes of assembly with the more advanced concept of nanoarchitectonics. In this perspective, we summarize research on self-assembly of amphiphilic molecules such as lipids, surfactants or block copolymers that are a focus of interest for many colloid, polymer, and materials scientists and which have become increasingly important in emerging nanotechnology and practical applications, latter of which are often accomplished by amphiphile-like polymers. Because the fundamental science of amphiphiles was initially developed for their solution assembly then transferred to assemblies on surfaces as a development of nanotechnological techniques, this perspective attempts to mirror this development by introducing solution systems and progressing to interfacial systems, which are roughly categorized as (i) basic properties of amphiphiles, (ii) self-assembly of amphiphiles in bulk phases, (iii) assembly on static surfaces, (iv) assembly at dynamic interfaces, and (v) advanced topics from simulation to application. This progression also represents the evolution of amphiphile science and technology from simple assemblies to advanced assemblies to nanoarchitectonics.

  20. 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

  1. The role of amphiphiles

    NARCIS (Netherlands)

    Hoekstra, F.A.; Golovina, E.A.

    2002-01-01

    This paper reviews our work on the partitioning of amphiphilic compounds from the cytoplasm into membranes during drying of plant systems, and discusses how relevant this phenomenon might be for anhydrobiosis. Amphiphilic guest molecules do partition into membranes and oil bodies, as demonstrated by

  2. Change in the Affinity of Ethylene Glycol Methacrylate Phosphate Monomer and Its Polymer Anchored on a Graphene Oxide Platform toward Uranium(VI) and Plutonium(IV) Ions.

    Science.gov (United States)

    Chappa, Sankararao; Singha Deb, Ashish K; Ali, Sk Musharaf; Debnath, A K; Aswal, D K; Pandey, Ashok K

    2016-03-24

    The complexation behavior of the carbonyl and phosphoryl ligating groups bearing ethylene glycol methacrylate phosphate (EGMP) monomer and its polymer fixed on a graphene oxide (GO) platform was studied to understand the coordination ability of segregated EGMP units and polymer chains toward UO2(2+) and Pu(4+) ions. The cross-linked poly(EGMP) gel and EGMP dissolved in solution have a similar affinity toward these ions. UV-initiator induced polymerization was used to graft poly(EGMP) on the GO platform utilizing a double bond of EGMP covalently fixed on it. X-ray photoelectron spectroscopy (XPS) of the GO and GO-EGMP was done to confirm covalent attachment of the EGMP via a -C-O-P- link between GO and EGMP. The extent of poly(EGMP) grafting on GO by thermal analyses was found to be 5.88 wt %. The EGMP units fixed on the graphene oxide platform exhibited a remarkable selectivity toward Pu(4+) ions at high HNO3 conc. where coordination is a dominant mode involved in the sorption of ions. The ratio of distribution coefficients of Pu(IV) to U(VI) (DPu(IV)/DU(VI)) followed a trend as cross-linked poly(EGMP) (0.95) ions with the EGMP molecule anchored on GO in the presence of nitrate ions. This computational modeling suggested that Pu(4+) ion formed a strong coordination complex with phosphoryl and carbonyl ligating groups of the GO-EGMP as compared to UO2(2+) ions. Thus, the nonselective EGMP becomes highly selective to Pu(IV) ions when it interacts as a single unit fixed on a GO platform.

  3. Change in the Affinity of Ethylene Glycol Methacrylate Phosphate Monomer and Its Polymer Anchored on a Graphene Oxide Platform toward Uranium(VI) and Plutonium(IV) Ions.

    Science.gov (United States)

    Chappa, Sankararao; Singha Deb, Ashish K; Ali, Sk Musharaf; Debnath, A K; Aswal, D K; Pandey, Ashok K

    2016-03-24

    The complexation behavior of the carbonyl and phosphoryl ligating groups bearing ethylene glycol methacrylate phosphate (EGMP) monomer and its polymer fixed on a graphene oxide (GO) platform was studied to understand the coordination ability of segregated EGMP units and polymer chains toward UO2(2+) and Pu(4+) ions. The cross-linked poly(EGMP) gel and EGMP dissolved in solution have a similar affinity toward these ions. UV-initiator induced polymerization was used to graft poly(EGMP) on the GO platform utilizing a double bond of EGMP covalently fixed on it. X-ray photoelectron spectroscopy (XPS) of the GO and GO-EGMP was done to confirm covalent attachment of the EGMP via a -C-O-P- link between GO and EGMP. The extent of poly(EGMP) grafting on GO by thermal analyses was found to be 5.88 wt %. The EGMP units fixed on the graphene oxide platform exhibited a remarkable selectivity toward Pu(4+) ions at high HNO3 conc. where coordination is a dominant mode involved in the sorption of ions. The ratio of distribution coefficients of Pu(IV) to U(VI) (DPu(IV)/DU(VI)) followed a trend as cross-linked poly(EGMP) (0.95) theory computations have been performed for the complexation of UO2(2+) and Pu(4+) ions with the EGMP molecule anchored on GO in the presence of nitrate ions. This computational modeling suggested that Pu(4+) ion formed a strong coordination complex with phosphoryl and carbonyl ligating groups of the GO-EGMP as compared to UO2(2+) ions. Thus, the nonselective EGMP becomes highly selective to Pu(IV) ions when it interacts as a single unit fixed on a GO platform. PMID:26926256

  4. Preparation and Characterization of Amphiphilic Triblock Terpolymer-Based Nanofibers as Antifouling Biomaterials

    KAUST Repository

    Cho, Youngjin

    2012-05-14

    Antifouling surfaces are critical for the good performance of functional materials in various applications including water filtration, medical implants, and biosensors. In this study, we synthesized amphiphilic triblock terpolymers (tri-BCPs, coded as KB) and fabricated amphiphilic nanofibers by electrospinning of solutions prepared by mixing the KB with poly(lactic acid) (PLA) polymer. The resulting fibers with amphiphilic polymer groups exhibited superior antifouling performance to the fibers without such groups. The adsorption of bovine serum albumin (BSA) on the amphiphilic fibers was about 10-fold less than that on the control surfaces from PLA and PET fibers. With the increase of the KB content in the amphiphilic fibers, the resistance to adsorption of BSA was increased. BSA was released more easily from the surface of the amphiphilic fibers than from the surface of hydrophobic PLA or PET fibers. We have also investigated the structural conformation of KB in fibers before and after annealing by contact angle measurements, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and coarse-grained molecular dynamics (CGMD) simulation to probe the effect of amphiphilic chain conformation on antifouling. The results reveal that the amphiphilic KB was evenly distributed within as-spun hybrid fibers, while migrated toward the core from the fiber surface during thermal treatment, leading to the reduction in antifouling. This suggests that the antifouling effect of the amphiphilic fibers is greatly influenced by the arrangement of amphiphilic groups in the fibers. © 2012 American Chemical Society.

  5. Amphiphile nanoarchitectonics: from basic physical chemistry to advanced applications

    Energy Technology Data Exchange (ETDEWEB)

    Ramanathan, Nathan Muruganathan [ORNL; Shrestha, Lok Kumar [International Center for Materials Nanoarchitectonics (MANA); Mori, Taizo [International Center for Materials Nanoarchitectonics (MANA); Ji, Dr. Qingmin [National Institute for Materials Science, Tsukuba, Japan; Hill, Dr. Jonathan P [National Institute for Materials Science, Tsukuba, Japan; Ariga, Katsuhiko [National Institute for Materials Science, Tsukuba, Japan

    2013-01-01

    Amphiphiles, either synthetic or natural, are structurally simple molecules with the unprecedented capacity to self-assemble into complex, hierarchical geometries in nanospace. Effective self-assembly processes of amphiphiles are often used to mimic biological systems, such as, assembly of lipids and proteins, which has paved a way for bottom-up nanotechnology with bio-like advanced functions. Recent developments on nanostructure formation combine simple processes of assembly with the more advanced concept of nanoarchitectonics. In this pespective, we summarize research on self-assembly of amphiphilic molecules such as lipids, surfactants or block copolymers that are a focus of interest for many colloid, polymer, and materials scientists and which have become increasingly important in emerging nanotechnology. Because the fundamental science of amphiphiles was initially developed for their solution assembly then transferred to assemblies on surfaces as a development of nanotechnological technique, this perspective attempts to mirro this development by introducing solution systems and progressing to interfacial systems, which are roughly categorized as (i) basic properties of amphiphiles, (ii) self-assembly of amphiphiles in bulk phases, (iii) assembly on static surfaces, (iv) assembly at dynamic interfaces, and (v) advanced topics from simulation to application. This progression also represents the evolution of amphiphile science and technology from simple assemblies to advanced assemblies to nanoarchitectonics.

  6. Release kinetics of controlled release formulations of thiamethoxam employing nano-ranged amphiphilic PEG and diacid based block polymers in soil.

    Science.gov (United States)

    Sarkar, Dhruba Jyoti; Kumar, Jitendra; Shakil, N A; Walia, S

    2012-01-01

    Amphiphilic copolymers, synthesized from poly(ethylene glycols) and various aliphatic and aromatic diacids, which self-assemble into nanomicellar aggregates in aqueous media, were used to develop controlled release (CR) formulations of thiamethoxam (3-(2-chloro-1,3-thiazol-5-ylmethyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro)amine) using encapsulation technique Formulations were characterised by Infrared (IR) spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Encapsulation efficiency, loading capacity and stability after accelerated storage test of the developed formulations were checked. The kinetics of thiamethoxam, released in sandy loam soil from the different formulations was studied. Release from the commercial formulation was faster than the CR formulations. The time taken for release of 50 % of thiamethoxam ranged from 3.56 to 6.07 days for the CR formulations. Although the diffusion exponent (n value) of thiamethoxam in soil ranged from 0.532 to 0.881 in the tested formulations showing non-Fickian transport. These CR formulations may be used in safer, effective and economic crop protection. PMID:22702832

  7. Drug-polymer interactions at water-crystal interfaces and implications for crystallization inhibition: molecular dynamics simulations of amphiphilic block copolymer interactions with tolazamide crystals.

    Science.gov (United States)

    Gao, Yi; Olsen, Kenneth W

    2015-07-01

    A diblock copolymer, poly(ethylene glycol)-block-poly(lactic acid) (PEG-b-PLA), modulates the crystal growth of tolazamide (TLZ), resulting in a crystal morphology change from needles to plates in aqueous media. To understand this crystal surface drug-polymer interaction, we conducted molecular dynamics simulations on crystal surfaces of TLZ in water containing PEG-b-PLA. A 130-ns simulation of the polymer in a large water box was run before initiating 50 ns simulations with each of the crystal surfaces. The simulations demonstrated differentiated drug-polymer interactions that are consistent with experimental studies. Interaction of PEG-b-PLA with the (001) face occurred more rapidly (≤10 ns) and strongly (total interaction energy of -121.1 kJ/mol/monomer) than that with the (010) face (∼35 ns, -85.4 kJ/mol/monomer). There was little interaction with the (100) face. Hydrophobic and van der Waals (VDW) interactions were the dominant forces, accounting for more than 90% of total interaction energies. It suggests that polymers capable of forming strong hydrophobic and VDW interactions might be more effective in inhibiting crystallization of poorly water-soluble and hydrophobic drugs in aqueous media (such as gastrointestinal fluid) than those with hydrogen-bonding capacities. Such in-depth analysis and understanding facilitate the rational selection of polymers in designing supersaturation-based enabling formulations. PMID:26045147

  8. Vers la catalyse d'hydroformylation biphasique au rhodium supportée sur des polymères cœur-coquille amphiphiles

    OpenAIRE

    Cardozo Perez, Andrés Fernando

    2012-01-01

    Ce travail développe une nouvelle approche de la catalyse biphasique aqueuse qui repose sur la construction de micelles réticulées à partir de polymères de type cœur-coquille. Le catalyseur (Rh) doit être incorporé sur les ligands du polymère dans la couche interne lipophile et la coquille hydrophile externe permettra de le séparer aisément du milieu réactionnel organique (oct-1-ène, nonanal, pour la réaction modèle d'hydroformylation choisie). La première partie du projet a donc consisté à p...

  9. Curvature-coupled hydration of Semicrystalline Polymer Amphiphiles yields flexible Worm Micelles but favors rigid Vesicles: polycaprolactone-based block copolymers

    OpenAIRE

    Rajagopal, Karthikan; Mahmud, Abdullah; Christian, David A.; Pajerowski, J. David; Brown, Andre E. X.; Sharon M Loverde; Discher, Dennis E.

    2010-01-01

    Crystallization processes are in general sensitive to detailed conditions, but our present understanding of underlying mechanisms is insufficient. A crystallizable chain within a diblock copolymer assembly is expected to couple curvature to crystallization and thereby impact rigidity as well as preferred morphology, but the effects on dispersed phases have remained unclear. The hydrophobic polymer polycaprolactone (PCL) is semi-crystalline in bulk (Tm = 60°C) and is shown here to generate fle...

  10. Cationic amphiphilic non-hemolytic polyacrylates with superior antibacterial activity.

    Science.gov (United States)

    Punia, Ashish; He, Edward; Lee, Kevin; Banerjee, Probal; Yang, Nan-Loh

    2014-07-01

    Acrylic copolymers with appropriate compositions of counits having cationic charge with 2-carbon and 6-carbon spacer arms can show superior antibacterial activities with concomitant very low hemolytic effect. These amphiphilic copolymers represent one of the most promising synthetic polymer antibacterial systems reported. PMID:24854366

  11. Blends of Amphiphilic, Hyperbranched Polyesters and Different Polyolefins

    NARCIS (Netherlands)

    Schmaljohann, D.; Pötschke, P.; Hässler, R.; Voit, B.I.; Froehling, P.E.; Mostert, B.; Loontjens, J.A.

    1999-01-01

    A hyperbranched polyester based on 3,5-dihydroxybenzoic acid was completely modified with dodecanoyl chloride to result in an amphiphilic, globular polymer, which has a polar core and a nonpolar outer sphere with the ability both to incorporate an organic dye and to interact with a nonpolar matrix.

  12. FRP-to-concrete joint assemblies anchored with multiple FRP anchors: experimental investigation

    OpenAIRE

    Zhang, H.; Smith, ST

    2010-01-01

    Higher strains can be developed in fibre-reinforced polymer (FRP) composites which are bonded to the surfaces of concrete members if the FRP is anchored. Anchors made from FRP (also known as FRP spike anchors but herein referred to as FRP anchors) are a promising type of anchorage as they can be applied to a variety of different shaped structural elements and they have been shown to be effective in en-hancing the strain capacity of externally bonded FRP. Limited research, however, has been co...

  13. New amphiphilic glycopolymers by click functionalization of random copolymers – application to the colloidal stabilisation of polymer nanoparticles and their interaction with concanavalin A lectin

    Directory of Open Access Journals (Sweden)

    Otman Otman

    2010-06-01

    Full Text Available Glycopolymers with mannose units were readily prepared by click chemistry of an azido mannopyranoside derivative and a poly(propargyl acrylate-co-N-vinyl pyrrolidone. These glycopolymers were used as polymer surfactants, in order to obtain glycosylated polycaprolactone nanoparticles. Optimum stabilization for long time storage was achieved by using a mixture of glycopolymers and the non-ionic triblock copolymer Pluronic® F-68. The mannose moieties are accessible at the surface of nanoparticles and available for molecular recognition by concanavalin A lectin. Interaction of mannose units with the lectin were evaluated by measuring the changes in nanoparticles size by dynamic light scattering in dilute media.

  14. Rate of permeabilization of giant vesicles by amphiphilic polyacrylates compared to the adsorption of these polymers onto large vesicles and tethered lipid bilayers.

    Science.gov (United States)

    Vial, F; Cousin, F; Bouteiller, L; Tribet, C

    2009-07-01

    We examined by fluorescence microscopy the permeabilization of giant vesicles by hydrophobically modified polyacrylates (called amphipols). Amphipols trigger permeabilization to FITC-dextran of egg-PC/DPPA vesicles with no breakage of the lipid bilayers. The polyanionic amphipols were passing through bilayers as shown by permeabilization of multilamellar vesicles. Remarkably, the vesicles were not simultaneously permeable but became leaky one after the other. Altogether, our observations suggest a random formation of pores having diameters above a few nanometers. Decreasing pH and increasing ionic strength and polymer concentration were increasing the rate of permeabilization. The rate and efficiency of permeabilization was compared to the rate and density of adsorption of amphipols onto lipid membranes (as estimated by titration calorimetry onto large unilamellar vesicles and neutron reflectivity measurements on tethered bilayers). The polymer adsorption layer is built up in a few minutes. We conclude that the rate-limiting step for permeabilization is not the adsorption from the bulk solution but relates to slow intramembrane reorganizations. PMID:19371041

  15. Amphiphiles Self-Assembly: Basic Concepts and Future Perspectives of Supramolecular Approaches

    Directory of Open Access Journals (Sweden)

    Domenico Lombardo

    2015-01-01

    Full Text Available Amphiphiles are synthetic or natural molecules with the ability to self-assemble into a wide variety of structures including micelles, vesicles, nanotubes, nanofibers, and lamellae. Self-assembly processes of amphiphiles have been widely used to mimic biological systems, such as assembly of lipids and proteins, while their integrated actions allow the performance of highly specific cellular functions which has paved a way for bottom-up bionanotechnology. While amphiphiles self-assembly has attracted considerable attention for decades due to their extensive applications in material science, drug and gene delivery, recent developments in nanoscience stimulated the combination of the simple approaches of amphiphile assembly with the advanced concept of supramolecular self-assembly for the development of more complex, hierarchical nanostructures. Introduction of stimulus responsive supramolecular amphiphile assembly-disassembly processes provides particularly novel approaches for impacting bionanotechnology applications. Leading examples of these novel self-assembly processes can be found, in fact, in biosystems where assemblies of different amphiphilic macrocomponents and their integrated actions allow the performance of highly specific biological functions. In this perspective, we summarize in this tutorial review the basic concept and recent research on self-assembly of traditional amphiphilic molecules (such as surfactants, amphiphile-like polymers, or lipids and more recent concepts of supramolecular amphiphiles assembly which have become increasingly important in emerging nanotechnology.

  16. Interaction between amphiphilic ionic liquid 1-butyl-3-methylimidazolium octyl sulfate and anionic polymer of sodium polystyrene sulfonate in aqueous medium

    Science.gov (United States)

    Barhoumi, Z.; Saini, M.; Amdouni, N.; Pal, A.

    2016-09-01

    The micellization of an aqueous solution of the surface active ionic liquid (SAIL), 1-butyl-3-methylimidazolium octylsufate (C4mim)(C8OSO3) and its interaction with an anionic polymer sodium polystyrene sulfonate, (NaPSS) were studied using conductimetry, tensiometry and fluorimetry. Surface tension profile shows a more dramatic increase in the value of surface tension of aqueous (C4mim)(C8OSO3) before the critical micelle concentration (cmc) of IL. The critical micelle concentration (cmc) value of this surfactant was found out from conductance measurements. The thermodynamic parameters, i.e., Gibb's free energy, enthalpy, and entropy of micellization of the IL in aqueous solution have been calculated. Behavior of fluorescence probe confirms the binding interactions between SAIL and the polyelectrolyte.

  17. Synthesis of antibacterial amphiphilic elastomer based on polystyrene-block-polyisoprene-block-polystyrene via thiol-ene addition

    Energy Technology Data Exchange (ETDEWEB)

    Keleş, Elif, E-mail: elifkelesh@hotmail.com [Department of Chemistry, Bülent Ecevit University, Zonguldak 67100 (Turkey); Hazer, Baki, E-mail: bhazer2@yahoo.com [Department of Chemistry, Bülent Ecevit University, Zonguldak 67100 (Turkey); Cömert, Füsun B. [Department of Microbiology, Faculty of Medicine, Bülent Ecevit University, 67600 Zonguldak (Turkey)

    2013-04-01

    A new type of amphiphilic antibacterial elastomer has been described. Thermoplastic elastomer, polystyrene–block-polyisoprene–block-polystyrene (PS–b-PI–b-PS) triblock copolymer was functionalized in toluene solution by free radical mercaptan addition in order to obtain an amphiphilic antibacterial elastomer. Thiol terminated PEG was grafted through the double bonds of PS–b-PI–b-PS via free radical thiol-ene coupling reaction. The antibacterial properties of the amphiphilic graft copolymers were observed. The original and the modified polymers were used to create microfibers in an electro-spinning process. Topology of the electrospun micro/nanofibers were studied by using scanning electron microscopy (SEM). The chemical structures of the amphiphilic comb type graft copolymers were elucidated by the combination of elemental analysis, {sup 1}H NMR, {sup 13}C NMR, GPC and FTIR. - Graphical abstract: Double bonds of polyisoprene units in polystyrene–block-polyisoprene–block-polystyrene triblock copolymer were partially capped with PEG containing mercapto end group via thiol-ene addition in order to obtain antibacterial amphiphilic elastomer. Nano fibers from amphiphilic graft polymers solution were produced by electrospinning. The PEG grafted copolymer inhibits very effectively bacterial growth. Highlights: ► A commercial synthetic elastomer was grafted with PEG to obtain amphiphilic elastomer. ► Amphiphilic elastomer shows antibacterial properties. ► Electrospun micro fibers of the amphiphilic elastomer tend to globular formation.

  18. Characterization and Synthesis of Rodex-responsive and Amphiphilic Comb-like Block Polymer%还原响应性两亲性梳型聚合物的合成及表征

    Institute of Scientific and Technical Information of China (English)

    赵天靓; 王薇; 刘大军

    2015-01-01

    As an initiator with alkoxyamino polyethylene glycol, we trigger the ring opening polymerization forγ-propargyl -L- carboxy glutamic -N- within anhydride (PLG-NCA) to obtain amphiphilic block copolymer. Based on these steps,we use click method to synthesize disulfide-labeled stimuli-responsive degradation comb-like block copoly-mer. At last, the generated polymer generates degradable and amphipathic micelles with sensitivity by self-assemble. These micelles with sensitivity are used to package,transport and release the cancer drugs. These micelles also have a higher stability and a better drug release. The experiment adopts doxorubicin hydrochloride as the wrapping drug by self-assemble in the solution of PBS of 1/15mol Ph=7.4.%以端氨基功能化的聚乙二醇单甲醚为引发剂,引发γ-炔丙基-L-谷氨酸-N-羧基内酸酐(PLG-NCA)开环聚合反应,获得聚氨基酸聚乙二醇两亲性嵌段共聚物。并以此为基础,用click方法合成带有二硫键标记的还原敏感性的可降解两亲性梳型嵌段聚合物。最后所得的这种聚合物在水溶液中自主装形成可降解的两亲性的敏感性胶束。这种带有敏感性的胶束可以用于抗癌药物的包覆以及运输和适时的释放;这种胶束具有更高的稳定性和更高的药物释放性。实验采用盐酸阿霉素作为包裹药物,在1/15mol pH=7.4的PBS溶液中进行自主装包裹药物。

  19. Large-scale dissipative particle dynamics simulations of self-assembly amphiphilic systems†

    Science.gov (United States)

    Li, Xuejin; Tang, Yu-Hang

    2014-01-01

    We present large-scale simulation results on the self-assembly of amphiphilic systems in bulk solution and under soft confinement. Self-assembled unilamellar and multilamellar vesicles are formed from amphiphilic molecules in bulk solution. The system is simulated by placing amphiphilic molecules inside large unilamellar vesicles (LUVs) and the dynamic soft confinement-induced self-assembled vesicles are investigated. Moreover, the self-assembly of sickle hemoglobin (HbS) is simulated in a crowded and fluctuating intracellular space and our results demonstrate that the HbS self-assemble into polymer fibers causing the LUV shape to be distorted. PMID:24938634

  20. Porous organic polymers with anchored aldehydes: A new platform for post-synthetic amine functionalization en route for enhanced CO2 adsorption properties

    KAUST Repository

    Guillerm, Vincent

    2014-01-01

    A novel porous organic polymer has been synthesized using the molecular building block approach to deliberately encompass aldehyde functionalities amenable to post functionalization. The resultant porous framework allows a facile, one-step quantitative and post-synthetic functionalization by amines, permitting enhanced CO2 sorption properties. © 2014 The Royal Society of Chemistry.

  1. 三元两亲共聚物作乳化剂制备核壳型改性酪素皮革涂饰剂%Synthesis of Core-shell Structural Modified Casein Leather Finishing Agent Based on a Ternary Amphiphilic Polymer

    Institute of Scientific and Technical Information of China (English)

    甘长凤; 徐群娜; 周建华; 马建中

    2013-01-01

    Modified casein leather finishing agents with core - shell structure prepared via emulsifier - free emulsion polymerization were studied, using a ternary amphiphilic polymer as the emulsifier. Effects of adding method and the amount of the emulsifier on the properties of the emulsion ( diluting stability, acid resistance, alkali resistance) and film properties ( water resistance, mechanical properties) were investigated. Latex structure, morphology and particle size were characterized by Infrared Spectrosco-py (FT-IR), Transmission Electron Microscopy (TEM) and Dynamic Laser Light Scattering (DLS), respectively. The best properties of modified casein is obtained when the emulsifier is added after the monomers with the amount 4%. Compared with those of control system (without emulsifiers) , water resistance, tensile strength and breaking elongation of films formed by modified casein based on ternary amphiphilic polymer are increased. The results of FT - IR suggest that ternary amphiphilic polymer successfully graft on modified casein polymer. TEM and DLS show that particles size of modified casein based on ternary amphiphilic polymer are about 40 ~ 50 nm with obvious core - shell structure and uniform distribution.%采用无皂乳液聚合法同时引入三元两亲共聚物作乳化剂,合成具有核壳结构的聚丙烯酸酯改性酪素皮革涂饰剂,考察了乳化剂的加入方式及其用量对乳液性能(稀释稳定性、耐酸性、耐碱性等)及成膜性能(耐水性、机械力学性能)的影响,并分别通过红外光谱(Fr-IR)、透射电镜(TEM)和动态激光光散射(DLS),对乳液结构、形貌和粒径大小进行表征.结果表明:当三元两亲性共聚物在单体后加入,用量为4%时,制备的皮革涂饰剂性能最优.与未采用三元两亲共聚物做乳化剂制备的乳液相比,采用本方法所制备的乳液成膜耐水性、抗张强度和断裂伸长率均有所提高.FT-IR谱图显示三元两亲共聚物成功接

  2. Hypersensitivity to Suture Anchors

    Directory of Open Access Journals (Sweden)

    Masafumi Goto

    2013-01-01

    Full Text Available Hypersensitivity to suture anchor is extremely rare. Herein, we present a case in which hypersensitivity to suture anchor was strongly suspected. The right rotator cuff of a 50-year-old woman was repaired with a metal suture anchor. Three weeks after the surgery, she developed erythema around her face, trunk, and hands, accompanied by itching. Infection was unlikely because no abnormalities were detected by blood testing or by medical examination. Suspicious of a metallic allergy, a dermatologist performed a patch testing 6 months after the first surgery. The patient had negative reactions to tests for titanium, aluminum, and vanadium, which were the principal components of the suture anchor. The anchor was removed 7 months after the first surgery, and the erythema disappeared immediately. When allergic symptoms occur and persist after the use of a metal anchor, removal should be considered as a treatment option even if the patch test result is negative.

  3. Comparison of Facially Amphiphilic versus Segregated Monomers in the Design of Antibacterial Copolymers

    OpenAIRE

    Gabriel, Gregory J.; Maegerlein, Janet A.; Nelson, Christopher F.; Dabkowski, Jeffrey M.; Eren, Tarik; Nüsslein, Klaus; Tew, Gregory N.

    2009-01-01

    A direct comparison of two strategies for designing antimicrobial polymers is presented. Previously, we published several reports on the use of facially amphiphilic (FA) monomers which led to polynorbornenes with excellent antimicrobial activities and selectivities. Our polymers obtained by copolymerization of structurally similar segregated monomers, in which cationic and non-polar moieties reside on separate repeat units, led to polymers with less pronounced activities. A wide range of poly...

  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. Electrochemical redox responsive polymeric micelles formed from amphiphilic supramolecular brushes.

    Science.gov (United States)

    Feng, Anchao; Yan, Qiang; Zhang, Huijuan; Peng, Liao; Yuan, Jinying

    2014-05-11

    The end-decorated homopolymer poly(ε-caprolactone)-ferrocene threaded onto a β-cyclodextrin-functionalized main-chain polymer can form a class of amphiphilic noncovalent graft copolymers based on the host-guest interactions of the terminal groups on the side chains. These new supramolecular polymer brushes can further self-assemble into micellar aggregates that exhibit reversible assembly and disassembly behavior under an electrochemical redox trigger, which opens up a new route to building dynamic block copolymer topologies. PMID:24681929

  6. Amphiphiles for protein solubilization and stabilization

    Science.gov (United States)

    Gellman, Samuel Helmer; Chae, Pil Seok; Laible, Philip D.; Wander, Marc J.

    2012-09-11

    The invention provides amphiphiles for manipulating membrane proteins. The amphiphiles can feature carbohydrate-derived hydrophilic groups and branchpoints in the hydrophilic moiety and/or in a lipophilic moiety. Such amphiphiles are useful as detergents for solubilization and stabilization of membrane proteins, including photosynthetic protein superassemblies obtained from bacterial membranes.

  7. Susceptibility to anchoring effects

    Directory of Open Access Journals (Sweden)

    Todd McElroy

    2007-02-01

    Full Text Available Previous research on anchoring has shown this heuristic to be a very robust psychological phenomenon ubiquitous across many domains of human judgment and decision-making. Despite the prevalence of anchoring effects, researchers have only recently begun to investigate the underlying factors responsible for how and in what ways a person is susceptible to them. This paper examines how one such factor, the Big-Five personality trait of openness-to-experience, influences the effect of previously presented anchors on participants' judgments. Our findings indicate that participants high in openness-to-experience were significantly more influenced by anchoring cues relative to participants low in this trait. These findings were consistent across two different types of anchoring tasks providing convergent evidence for our hypothesis.

  8. Catalytic activity of Pt anchored onto graphite nanofiber-poly (3,4-ethylenedioxythiophene) composite toward oxygen reduction reaction in polymer electrolyte fuel cells

    International Nuclear Information System (INIS)

    Highlights: • GNF–PEDOT is explored as a catalyst support for PEFCs. • PEDOT bridges the Pt nanoparticles with GNF via π–π interaction. • Binding strength between Pt and GNF is improved and hence mitigates Pt aggregation. • GNF–PEDOT composite enhances ORR activity and durability in fuel cells. -- Abstract: The potential of graphite nanofiber (GNF)–Poly(3,4-ethylenedioxythiophene) (PEDOT) composite is explored as a catalyst support for polymer electrolyte fuel cells (PEFCs). Due to electron accepting nature of GNF and electron donating nature of PEDOT, the monomer EDOT adsorbs on the surface of GNF due to strong electrostatic π–π interaction. Pt nanoparticles are impregnated on GNF–PEDOT composite by ethylene glycol reduction method and their effects on electro catalytic activity for oxygen reduction reaction (ORR) are systemically studied. Pt particles supported on GNF–PEDOT with catalyst loading of 0.2 mg cm−2 exhibit a peak power density of 537 mW cm−2 at a load current density of 1120 mA cm−2, while it was only 338 mW cm−2 at a load current density of 720 mA cm−2 in case of Pt particles supported on pristine GNF. The superior behavior of GNF–PEDOT supported Pt catalyst could be exclusively credited to the high graphitic nature of GNF and their mild functionalization with PEDOT increasing uniform dispersion of Pt. Indeed, the non-destructive functionalization of GNF with conducting polymer, such as PEDOT, makes them promising catalyst-supports for PEFCs

  9. Anchoring visions in organizations

    DEFF Research Database (Denmark)

    Simonsen, Jesper

    1999-01-01

    This paper introduces the term 'anchoring' within systems development: Visions, developed through early systems design within an organization, need to be deeply rooted in the organization. A vision's rationale needs to be understood by those who decide if the vision should be implemented as well...... anchoring is considered to be a main activity, is outlined. The task of anchoring visions is described, and techniques and activities are suggested with respect to those actors that have to act on the visions and the recommendations from a design proposal. The paper concludes that obtaining appropriate...

  10. Anchor Trial Launch

    Science.gov (United States)

    NCI has launched a multicenter phase III clinical trial called the ANCHOR Study -- Anal Cancer HSIL (High-grade Squamous Intraepithelial Lesion) Outcomes Research Study -- to determine if treatment of HSIL in HIV-infected individuals can prevent anal canc

  11. Susceptibility to anchoring effects

    OpenAIRE

    Todd McElroy; Keith Dowd

    2007-01-01

    Previous research on anchoring has shown this heuristic to be a very robust psychological phenomenon ubiquitous across many domains of human judgment and decision-making. Despite the prevalence of anchoring effects, researchers have only recently begun to investigate the underlying factors responsible for how and in what ways a person is susceptible to them. This paper examines how one such factor, the Big-Five personality trait of openness-to-experience, influences the effect of previously p...

  12. Unimolecular micelles of amphiphilic cyclodextrin-core star-like block copolymers for anticancer drug delivery.

    Science.gov (United States)

    Xu, Zhigang; Liu, Shiying; Liu, Hui; Yang, Cangjie; Kang, Yuejun; Wang, Mingfeng

    2015-11-11

    Well-defined star-like amphiphilic polymers composed of a β-cyclodextrin core, from which 21 hydrophobic poly(lactic acid) arms and hydrophilic poly(ethylene glycol) arms are grafted sequentially, form robust and uniform unimolecular micelles that are biocompatible and efficient in the delivery of anticancer drugs. PMID:26121632

  13. Structure of adsorption layers of amphiphilic copolymers on inorganic or organic particle surfaces

    OpenAIRE

    Bulychev, Nikolay; Dervaux, Bart; Dimberger, Klaus; Zubov, Vitali; Du Prez, Filip; Eisenbach, Claus D

    2010-01-01

    The structure of adsorption layers of amphiphilic block and block-like copolymers of poly(isobornyl acrylate) and poly(acrylic acid) on the surface of hydrophilic titanium dioxide and hydrophobic copper phthalocyanine (CuPc) pigments in an aqueous studied by the electrokinetic sonic amplitude (ESA) method. The electroacoustic behaviour of the polyelectrolyte block copolymer-coated particles could be described in the context of the polymer gel layer theory. The polymer layer around the particl...

  14. Synergistic effect of a new wedge-bond-type anchor for CFRP tendons

    Institute of Scientific and Technical Information of China (English)

    谢桂华; 刘荣桂; 陈蓓; 李明君; 石天罡

    2015-01-01

    In order to improve the anchoring force of anchors for carbon fiber reinforced polymer (CFRP) tendons further, a new wedge-bond-type anchor for CFRP tendons was developed. The increment in anchoring force induced by the clamping segment of anchor was studied. Taking the deformation of all parts in clamping segment in the transverse direction into consideration, the calculation formula for the increment of anchoring force was proposed based on the linear elastic hypotheses. The proposed model is verified by experiments and conclusions are drawn that the anchoring force is influenced mainly by the inclination angle of clamping pieces, the length of clamping part and the thickness of bonding medium. Especially, the thickness of bonding medium should be lowered in design to improve the synergistic effect of anchors.

  15. Non-Surface Activity of Cationic Amphiphilic Diblock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, Rati Ranjan; Yamada, Tasuku; Matsuoka, Hideki, E-mail: ratiranjan@immt.res.in, E-mail: matsuoka@star.polym.kyoto-u.ac.jp [Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2011-09-19

    Cationic amphiphilic diblock copolymers containing quaternized poly (2-vinylpyridine) chain as a hydrophilic segment (PIp-b-PNMe2VP) were synthesized by living anionic polymerization. By IR measurement, we confirmed the quaternization of the polymer (PIp-b-PNMe2VP), and determined the degree of quaternization by conductometric titration. The surface tension experiment showed that the polymers are non-surface active in nature. The foam formation of the polymer solutions was also investigated with or without added salt. Almost no foam formation behavior was observed without added salt, while a little foam was observed in the presence of 1M NaCl. The critical micelle concentration (cmc) of the diblock copolymers with 3 different chain lengths was measured by the static light scattering method. The cmc values obtained in this study were much lower than the values obtained for anionic non-surface active diblock polymers studied previously. The hydrodynamic radii of the polymer micelle increased slightly in the presence of 1 M NaCl. The transmission electron microscopic images revealed spherical micelles in pure water. In the presence of salt, the cmc values increased as was the case for anionic polymers, which is unlike conventional surfactant systems but consistent with non-surface active anionic block copolymers. The microviscosity of the micelle core was evaluated using Coumarin-153 as a fluorescent anisotropy probe using steady-sate fluorescence depolarization. Non-surface activity has been proved to be universal for ionic amphiphilic block copolymers both for anionic and cationic. Hence, the origin of non-surface activity is not the charged state of water surface itself, but should be an image charge repulsion at the air/water interface.

  16. Synthesis of Amphiphilic Block Copolymers for Use in Biomedical Applications

    OpenAIRE

    Carmichael-Baranauskas, Anita Yvonne

    2010-01-01

    The research presented in this thesis focuses on the synthesis of three amphiphilic block copolymer systems containing poly(ethylene oxide) (PEO) blocks. The polymer systems were developed for use in biomedical applications. The first of these is a series of poly(ethylene oxide-b¬-oxazoline) (PEO-b-POX) diblock copolymers for use in the progress towards novel non-viral gene transfer vectors. Poly(ethylene oxide-b¬-2-ethyl-2-oxazoline) (PEO-b-PEOX) and poly(ethylene oxide-b¬-2-methyl-2-o...

  17. Monte Carlo simulation for the micellar behavior of amphiphilic comb-like copolymers

    Institute of Scientific and Technical Information of China (English)

    冯莺; 隋家贤; 赵季若; 陈欣方

    2000-01-01

    Micellar behaviors in 2D and 3D lattice models for amphiphilic comb-like copolymers in water phase and in water/oil mixtures were simulated. A dynamical algorithm together with chain reptation movements was used in the simulation. Three-dimension displaying program was pro-grammed and free energy was estimated by Monte Carlo technigue. The results demonstrate that reduced interaction energy influences morphological structures of micelle and emulsion ??stems greatly; 3D simulation showing can display more direct images of morphological structures; the amphiphilic comb-like polymers with a hydrophobic main chain and hydrophilic side chains have lower energy in water than in oil.

  18. PARTITION-OPTIMIZED SINGLE EMULSION PARTICLES IMPROVE SUSTAINED RELEASE OF AMPHIPHILIC BUMPED KINASE INHIBITORS TO CONTROL MALARIA TRANSMISSION

    Directory of Open Access Journals (Sweden)

    Christina Yacoob

    2015-11-01

    Full Text Available Amphiphilic molecules are challenging to be incorporatedinto polymeric particles for sustained release due to their significant solubility in both water and organic solvent used in the fabrication process. Here, we investigated an extensive panel of fabrication methods for the incorporation and release of amphiphilic molecules, in particular, novel amphiphilic bumped kinase inhibitors (BKIs. Previously, BKIswere shown to reduce malaria transmission by blocking of gametocyte exflagellation. Prolonged BKI bioavailability for effective transmission blocking is crucial since infectious gametocytes circulate for several weeks inthe mammalian host, well beyond the half-life of BKIs. So far, delivery systems for sustained release of those BKIs have not been successfully formulated yet. Here we demonstrate that out of several delivery vehicles the partition-optimized single emulsion particles are the ideal system for incorporation and sustained release of amphiphilic BKIs. They increased the incorporation greater than 90% through optimized partitioning of amphiphilic molecules to the polymer phase and sustained release of BKIs up to several weeks with a reduction in the initial burst release. Overall this work provides a method for the incorporation and sustained release of amphiphilic BKIs, and can be adapted for other amphiphilic molecules.

  19. Synthesis of Dumbbell-shaped Hyperbranched Amphiphilic Block Copolymer by Controlled Atom Transfer Radical Polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Kyoung; An, Sung Guk; Cho, Chang Gi [Center for Advanced Functional Polymers, Department of Fiber and Polymer Science, Hanyang University, Seoul (Korea); Noh, Si Tae [Department of Chemical Engineering, Hanyang University, Ansan (Korea)

    2001-04-01

    Amphiphilic block copolymers containing hydrophilic ethylene glycol core and hyperbranched polystyrene (PS) arm were synthesized by atom transfer radical polymerization using hydrophilic macroinitiator and p-chloromethyl styrene (CMS) as AB type monomer. Hydrophilic poly(ethylene glycol)(PEG) macroinitiators with difuntional groups were synthesized by reacting PEG and 2-bromopropionyl bromide. The chemical structure, molecular weight, and polydispersity index of the amphiphilic block copolymer were characterized by {sup 1}H-NMR spectroscopy and GPC analysis. The molecular weight increased as the reaction time increased. Polydispersity index of the obtained polymer was relatively narrow (below 1.39). To control chain density of the hyperbranched PS, styrene and CMS were copolymerized. It was found that amphiphilic block copolymer molecule underwent conformational change in different solvents based on the result for {sup 1}H-NMR spectroscopic analysis. 29 refs., 8 figs., 2 tabs.

  20. Nano-Assemblies of Modified Cyclodextrins and Their Complexes with Guest Molecules: Incorporation in Nanostructured Membranes and Amphiphile Nanoarchitectonics Design

    OpenAIRE

    Leïla Zerkoune; Angelina Angelova; Sylviane Lesieur

    2014-01-01

    A variety of cyclodextrin-based molecular structures, with substitutions of either primary or secondary faces of the natural oligosaccharide macrocycles of α-, β-, or γ-cyclodextrins, have been designed towards innovative applications of self-assembled cyclodextrin nanomaterials. Amphiphilic cyclodextrins have been obtained by chemical or enzymatic modifications of their macrocycles using phospholipidyl, peptidolipidyl, cholesteryl, and oligo(ethylene oxide) anchors as well as variable numb...

  1. Tandem Facial Amphiphiles for Membrane Protein Stabilization

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Gotfryd, Kamil; Pacyna, Jennifer;

    2010-01-01

    We describe a new type of synthetic amphiphile that is intended to support biochemical characterization of intrinsic membrane proteins. Members of this new family displayed favorable behavior with four of five membrane proteins tested, and these amphiphiles formed relatively small micelles....

  2. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Purdy Drew, Kirstin R.; Sanders, Lori K.; Culumber, Zachary W.; Zribi, Olena; Wong, Gerard C.L.; (UIUC)

    2009-06-17

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

  3. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Drew, K.R.Purdy; Sanders, L.K.; Culumber, Z.W.; Zribi, O.; Wong, G.C.L.

    2009-05-21

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

  4. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    International Nuclear Information System (INIS)

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers

  5. Comparison of facially amphiphilic versus segregated monomers in the design of antibacterial copolymers.

    Science.gov (United States)

    Gabriel, Gregory J; Maegerlein, Janet A; Nelson, Christopher F; Dabkowski, Jeffrey M; Eren, Tarik; Nüsslein, Klaus; Tew, Gregory N

    2009-01-01

    A direct comparison of two strategies for designing antimicrobial polymers is presented. Previously, we published several reports on the use of facially amphiphilic (FA) monomers which led to polynorbornenes with excellent antimicrobial activities and selectivities. Our polymers obtained by copolymerization of structurally similar segregated monomers, in which cationic and non-polar moieties reside on separate repeat units, led to polymers with less pronounced activities. A wide range of polymer amphiphilicities was surveyed by pairing a cationic oxanorbornene with eleven different non-polar monomers and varying the comonomer feed ratios. Their properties were tested using antimicrobial assays and copolymers possessing intermediate hydrophobicities were the most active. Polymer-induced leakage of dye-filled liposomes and microscopy of polymer-treated bacteria support a membrane-based mode of action. From these results there appears to be profound differences in how a polymer made from FA monomers interacts with the phospholipid bilayer compared with copolymers from segregated monomers. We conclude that a well-defined spatial relationship of the whole polymer is crucial to obtain synthetic mimics of antimicrobial peptides (SMAMPs): charged and non-polar moieties need to be balanced locally, for example, at the monomer level, and not just globally. We advocate the use of FA monomers for better control of biological properties. It is expected that this principle will be usefully applied to other backbones such as the polyacrylates, polystyrenes, and non-natural polyamides. PMID:19021176

  6. Self-assembly behavior of a linear-star supramolecular amphiphile based on host-guest complexation.

    Science.gov (United States)

    Wang, Juan; Wang, Xing; Yang, Fei; Shen, Hong; You, Yezi; Wu, Decheng

    2014-11-01

    A star polymer, β-cyclodextrin-poly(l-lactide) (β-CD-PLLA), and a linear polymer, azobenzene-poly(ethylene glycol) (Azo-PEG), could self-assemble into a supramolecular amphiphilic copolymer (β-CD-PLLA@Azo-PEG) based on the host-guest interaction between β-CD and azobenzene moieties. This linear-star supramolecular amphiphilic copolymer further self-assembled into a variety of morphologies, including sphere-like micelle, carambola-like micelle, naan-like micelle, shuttle-like lamellae, tube-like fiber, and random curled-up lamellae, by tuning the length of hydrophilic or hydrophobic chains. The variation of morphology was closely related to the topological structure and block ratio of the supramolecular amphiphiles. These self-assembly structures could disassemble upon an ultraviolet (UV) light irradiation. PMID:25310380

  7. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion.

    Science.gov (United States)

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible addition-fragment transfer (RAFT) polymerization, was confirmed by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). While the hydrophilic PMOEP block within the amphiphilic block copolymer strongly binds to the enamel surface, the PMMA block forms a hydrophobic shell to prevent acid attack on tooth enamel, thus preventing/reducing acid erosion. The polymer treatment not only effectively decreased the mineral loss of hydroxyapatite (HAP) by 36-46% compared to the untreated control, but also protected the surface morphology of the enamel specimen following exposure to acid. Additionally, experimental results confirmed that low pH values and high polymer concentrations facilitate polymer binding. Thus, the preliminary data suggests that this new amphiphilic diblock copolymer has the potential to be used as a non-fluoride ingredient for mouth-rinse or toothpaste to prevent/reduce tooth erosion. PMID:25419457

  8. Terpene and dextran renewable resources for the synthesis of amphiphilic biopolymers.

    Science.gov (United States)

    Alvès, Marie-Hélène; Sfeir, Huda; Tranchant, Jean-François; Gombart, Emilie; Sagorin, Gilles; Caillol, Sylvain; Billon, Laurent; Save, Maud

    2014-01-13

    The present work shows the synthesis of amphiphilic polymers based on the hydrophilic dextran and the hydrophobic terpenes as renewable resources. The first step concerns the synthesis of functional terpene molecules by thiol-ene addition chemistry involving amino or carboxylic acid thiols and dihydromyrcenol terpene. The terpene-modified polysaccharides were subsequently synthesized by coupling the functional terpenes with dextran. A reductive amination step produced terpene end-modified dextran with 94% of functionalization, while the esterification step produced three terpene-grafted dextrans with a number of terpene units per dextran of 1, 5, and 10. The amphiphilic renewable grafted polymers were tested as emulsifiers for the stabilization of liquid miniemulsion of terpene droplets dispersed in an aqueous phase. The average hydrodynamic diameter of the stable droplets was observed at about 330 nm.

  9. Amphiphilic block copolymers in oil-water-surfactant mixtures: efficiency boosting, structure, phase behaviour and mechanism

    Science.gov (United States)

    Gompper, G.; Richter, D.; Strey, R.

    2001-10-01

    The effect of amphiphilic block copolymers on the phase behaviour and structure of ternary microemulsions in water, oil and non-ionic surfactant mixtures is reviewed. Recent experiments have revealed that the addition of small amounts of polyethylenepropylene-polyethyleneoxide block copolymer to the ternary systems leads to a dramatic increase in the volumes of oil and water solubilized into a bicontinuous microemulsion for a given surfactant volume fraction. While phase diagrams directly show the power of the amphiphilic block copolymers as efficiency boosters, the theoretical analysis in terms of bending energy discloses the mechanism for the efficiency boosting as due to the variation of the surfactant film curvature elasticity by tethered polymers in the form of mushrooms at the interface. Neutron scattering experiments employing a high-precision two-dimensional contrast variation technique confirm this picture and demonstrate that the polymer molecules uniformly decorate the surfactant film.

  10. Experimental study and mechanism analysis of the anti-pulling behavior of glass fiber reinforced polymer anti-float anchor%玻璃纤维增强聚合物抗浮锚杆抗拔性能试验研究与机制分析

    Institute of Scientific and Technical Information of China (English)

    张明义; 寇海磊; 白晓宇; 张宗强

    2014-01-01

    As a kind of vertical anchoring technique, the anti-float anchor has been widely used in China, whose performance has begun to receive more attentions from researchers. However, steels may be eroded easily by groundwater or chemical solutions, which will cause the reductions of mechanical strength and service life, especially in subway engineering the steel anti-float anchor is forbidden. Glass fiber reinforced polymer (GFRP) anti-float anchor is a new kind of material which is composed of resin matrix and glass fiber. Compared with steel anchor, the GFRP anti-float anchor has higher strength, corrosion-resistance and light weight behavior. The field tests show the feasibility of GFRP anti-float anchor through embedded bare fiber optics sensor technique. According to the test results, the GFRP anti-float anchor stress-strain behaviors, load transfer mechanism and failure mechanism are considered. The test indicates that GFRP anti-float anchor is basically about shear failure and pullout capacity of anchors with28 mm are 250 kN, which can be satisfied with engineering demands. The axial forces of anchors fall gradually with depth, and it will not bear load beyond certain length. Results show that the effect distance of axial forces is about 3.7 m when the length of bond part is in range of 3.95~6.95 m in moderately weathered granite,which indicates that GFRP anti-float anchors also exist critical anchorage depth. The shear stress on interface of anchor is not evenly distributed, which peak value is being driven down, and so as to the zero value. The research results can provide evidence for application of GFRP anti-float anchor.%抗浮锚杆作为一种竖向锚固技术在我国许多地区广泛应用,锚杆作为抗浮结构的核心其性能受到极大关注。但因钢材易腐蚀,传统金属锚杆的耐久性受到质疑,特别是地铁等地下工程存在杂散电流,限制了金属抗浮锚杆的应用。玻璃纤维增强聚合物(GFRP)

  11. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion

    OpenAIRE

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible add...

  12. One-Pot Synthesis, Encaspulation, and Solubilization of Size-Tuned Quantum Dots with Amphiphilic Multidentate Ligands

    OpenAIRE

    Kairdolf, Brad A.; SMITH, ANDREW M.; Nie, Shuming

    2008-01-01

    We report one-pot synthesis, encapsulation, and solubilization of high-quality quantum dots based on the use of amphiphilic and multidentate polymer ligands. In this “all-in-one” procedure, the resulting QDs are first capped by the multidentate ligand, and are then spontaneously encapsulated and solubilized by a second layer of the same multidentate polymer upon exposure to water. In addition to providing better control of nanocrystal nucleation and growth kinetics (including resistance to Os...

  13. Amphiphilic biopolymers (amphibiopols) as new surfactants for membrane protein solubilization

    Science.gov (United States)

    Duval-Terrié, Caroline; Cosette, Pascal; Molle, Gérard; Muller, Guy; Dé, Emmanuelle

    2003-01-01

    The aim of this study was to develop new surfactants for membrane protein solubilization, from a natural, biodegradable polymer: the polysaccharide pullulan. A set of amphiphilic pullulans (HMCMPs), differing in hydrophobic modification ratio, charge ratio, and the nature of the hydrophobic chains introduced, were synthesized and tested in solubilization experiments with outer membranes of Pseudomonas fluorescens. The membrane proteins were precipitated, and then resolubilized with various HMCMPs. The decyl alkyl chain (C10) was the hydrophobic graft that gave the highest level of solubilization. Decyl alkyl chain-bearing HMCMPs were also able to extract integral membrane proteins from their lipid environment. The best results were obtained with an amphiphilic pullulan bearing 18% decyl groups (18C10). Circular dichroism spectroscopy and membrane reconstitution experiments were used to test the structural and functional integrity of 18C10-solubilized proteins (OmpF from Escherichia coli and bacteriorhodopsin from Halobacterium halobium). Whatever their structure type (α or β), 18C10 did not alter either the structure or the function of the proteins analyzed. Thus, HMCMPs appear to constitute a promising new class of polymeric surfactants for membrane protein studies. PMID:12649425

  14. Structure-property relationship in cytotoxicity and cell uptake of poly(2-oxazoline) amphiphiles

    KAUST Repository

    Luxenhofer, Robert

    2011-07-01

    The family of poly(2-oxazoline)s (POx) is being increasingly investigated in the context of biomedical applications. We tested the relative cytotoxicity of POx and were able to confirm that these polymers are typically not cytotoxic even at high concentrations. Furthermore, we report structure-uptake relationships of a series of amphiphilic POx block copolymers that have different architectures, molar mass and chain termini. The rate of endocytosis can be fine-tuned over a broad range by changing the polymer structure. The cellular uptake increases with the hydrophobic character of the polymers and is observed even at nanomolar concentrations. Considering the structural versatility of this class of polymers, the relative ease of preparation and their stability underlines the potential of POx as a promising platform candidate for the preparation of next-generation polymer therapeutics.

  15. Terminal groups control self-assembly of amphiphilic block copolymers in solution

    Science.gov (United States)

    Grzelakowski, M.; Kita-Tokarczyk, K.

    2016-03-01

    The terminal groups of amphiphilic block copolymers are shown to control macromolecular self-assembly in aqueous solutions, in the micellar/lamellar region of the phase diagram. At the same concentration and using the same self-assembly conditions, dramatic differences are observed in polymer hydration and the resulting nano-/microstructure for two series of polymers with identical block chemistry and hydrophilic-lipophilic balance (HLB). This suggests a strong contribution from end groups to the hydration as the initial step of the self-assembly process, and could be conveniently used to guide the particle morphology and size. Additionally, for polymers with those head groups which drive vesicular structures, differences in membrane organization affect their physical properties, such as permeability.The terminal groups of amphiphilic block copolymers are shown to control macromolecular self-assembly in aqueous solutions, in the micellar/lamellar region of the phase diagram. At the same concentration and using the same self-assembly conditions, dramatic differences are observed in polymer hydration and the resulting nano-/microstructure for two series of polymers with identical block chemistry and hydrophilic-lipophilic balance (HLB). This suggests a strong contribution from end groups to the hydration as the initial step of the self-assembly process, and could be conveniently used to guide the particle morphology and size. Additionally, for polymers with those head groups which drive vesicular structures, differences in membrane organization affect their physical properties, such as permeability. Electronic supplementary information (ESI) available: Fig. S1: Particle diameters for hydrated NH2-ABA-NH2 polymers with different degrees of functionalization; Fig. S2: TEM characterization of compound micelles from BA-OH polymer after extrusion; Fig. S3: Cryo-TEM and stopped flow characterization of lipid vesicles; Fig. S4 and S5: NMR spectra for ABA and BA polymers

  16. Epstein on Anchors and Grounds

    Directory of Open Access Journals (Sweden)

    Guala Francesco

    2016-03-01

    Full Text Available The distinction between anchors and grounds is one of the most innovative contributions of The Ant Trap. In this commentary I will argue that the distinction suffers from an ambiguity between tokens and types. This leads Epstein to endorse pluralism about anchors and grounds, a position that is not justified in the book and to which there are plausible alternatives.

  17. Design of a multi-coordinating polymer as a platform for functionalizing metal, metal oxide and semiconductor nanocrystals

    Science.gov (United States)

    Wang, Wentao; Ji, Xin; Kapur, Anshika; Mattoussi, Hedi

    2016-03-01

    We introduce a new set of amphiphilic polymers as multifunctional, metal-coordinating ligands adapted to surfacefunctionalize quantum dots (QDs), iron oxide nanoparticles (IONPs) and gold nanoparticles/nanorods (AuNPs/AuNRs). The ligand design relies on the introduction of several anchoring groups, hydrophilic moieties and reactive functionalities into a polymer chain, via one-step nucleophilic addition reaction. Such synthetic scheme also allows the insertion of target biomolecules during the ligand synthesis. This functionalization strategy yields nanocrystals that exhibit long-term colloidal stability over a broad range of biological conditions, such as pH changes and when mixed with growth media. When zwitterion groups are used as hydrophilic motifs, this provides compact nanocrystals that are compatible with conjugation to proteins via metal-polyhistidine self-assembly. In addition, we show that QDs ligated with these polymers can engage in energy or charge transfer interactions. Furthermore, nanocrystals coated with folic acid-modified polymers could promote the delivery of nanoparticle-conjugates into cancer cells via folate receptormediated endocytosis.

  18. Aminoglycoside-derived amphiphilic nanoparticles for molecular delivery.

    Science.gov (United States)

    Miryala, Bhavani; Godeshala, Sudhakar; Grandhi, Taraka Sai Pavan; Christensen, Matthew D; Tian, Yanqing; Rege, Kaushal

    2016-10-01

    The development of effective drug carriers can lead to improved outcomes in a variety of disease conditions. Aminoglycosides have been used as antibacterial therapeutics, and are attractive as monomers for the development of polymeric materials in various applications. Here, we describe the development of novel aminoglycoside-derived amphiphilic nanoparticles for drug delivery, with an eye towards ablation of cancer cells. The aminoglycoside paromomycin was first cross-linked with resorcinol diglycidyl ether leading to the formation of a poly (amino ether), PAE. PAE molecules were further derivatized with methoxy-terminated poly(ethylene glycol) or mPEG resulting in the formation of mPEG-PAE polymer, which self-assembled to form nanoparticles. Formation of the mPEG-PAE amphiphile was characterized using (1)H NMR, (13)C NMR, gel permeation chromatography (GPC) and FTIR spectroscopy. Self-assembly of the polymer into nanoparticles was characterized using dynamic light scattering, zeta potential analyses, atomic force microscopy (AFM) and the pyrene fluorescence assay. mPEG-PAE nanoparticles were able to carry significant amounts of doxorubicin (DOX), presumably by means of hydrophobic interactions between the drug and the core. Cell-based studies indicated that mPEG-PAE nanoparticles, loaded with doxorubicin, were able to induce significant loss in viabilities of PC3 human prostate cancer, MDA-MB-231 human breast cancer, and MB49 murine bladder cancer cells; empty nanoparticles resulted in negligible losses of cell viability under the conditions investigated. Taken together, our results indicate that the mPEG-PAE nanoparticle platform is attractive for drug delivery in different applications, including cancer. PMID:27472455

  19. Synthesis of Polymer Grafted Magnetite Nanoparticle with the Highest Grafting Density via Controlled Radical Polymerization

    Directory of Open Access Journals (Sweden)

    Babu Kothandapani

    2009-01-01

    Full Text Available Abstract The surface-initiated ATRP of benzyl methacrylate, methyl methacrylate, and styrene from magnetite nanoparticle is investigated, without the use of sacrificial (free initiator in solution. It is observed that the grafting density obtained is related to the polymerization kinetics, being higher for faster polymerizing monomer. The grafting density was found to be nearly 2 chains/nm2for the rapidly polymerizing benzyl methacrylate. In contrast, for the less rapidly polymerizing styrene, the grafting density was found to be nearly 0.7 chain/nm2. It is hypothesized that this could be due to the relative rates of surface-initiated polymerization versus conformational mobility of polymer chains anchored by one end to the surface. An amphiphilic diblock polymer based on 2-hydroxylethyl methacrylate is synthesized from the polystyrene monolayer. The homopolymer and block copolymer grafted MNs form stable dispersions in various solvents. In order to evaluate molecular weight of the polymer that was grafted on to the surface of the nanoparticles, it was degrafted suitably and subjected to gel permeation chromatography analysis. Thermogravimetric analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to confirm the grafting reaction.

  20. Computational Amphiphilic Materials for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Naresh eThota

    2015-10-01

    Full Text Available Amphiphilic materials can assemble into a wide variety of morphologies and have emerged as a novel class of candidates for drug delivery. Along with a large number of experiments reported, computational studies have been also conducted in this field. At an atomistic/molecular level, computations can facilitate quantitative understanding of experimental observations and secure fundamental interpretation of underlying phenomena. This review summarizes the recent computational efforts on amphiphilic copolymers and peptides for drug delivery. Atom-resolution and time-resolved insights are provided from bottom-up to microscopically elucidate the mechanisms of drug loading/release, which are indispensable in the rational screening and design of new amphiphiles for high-efficacy drug delivery.

  1. Prediction on amphiphilicity of hypocrellin derivatives

    Institute of Scientific and Technical Information of China (English)

    谢杰; 马江华; 赵井泉

    2002-01-01

    Hypocrellins are most suitable for photodynamic therapy (PDT) of the diseases occurring in the superficial layer, such as microvascular diseases, because of their special absorption spectral properties. However, hypocrellins and most of their derivatives are basically lipophilic, while the hydrophilic derivatives lose the PDT activity in vivo. Therefore, the key problem for practical application of PDT of microvascular diseases focuses on finding the derivatives which possess optimized amphiphilicity. Herein, we developed a theoretical method to estimate the amphi-philicity of a molecule by the calculated average polarity. Compared with the experimentally measured results, the method is proved to be applicable. Based on the computation and available experimental results, it can be concluded that the derivative must have the polarities around C.22 for optimized amphiphilicity.

  2. Prediction on amphiphilicity of hypocrellin derivatives

    Institute of Scientific and Technical Information of China (English)

    谢杰; 马江华; 赵井泉

    2002-01-01

    Hypocrellins are most suitable for photodynamic therapy (PDT) of the diseases occurring in the superficial layer, such as microvascular diseases, because of their special absorption spectral properties. However, hypocrellins and most of their derivatives are basically lipophilic, while the hydrophilic derivatives lose the PDT activity in vivo. Therefore, the key problem for practical application of PDT of microvascular diseases focuses on finding the derivatives which possess optimized amphiphilicity. Herein, we developed a theoretical method to estimate the amphiphilicity of a molecule by the calculated average polarity. Compared with the experimentally measured results, the method is proved to be applicable. Based on the computation and available experimental results, it can be concluded that the derivative must have the polarities around 0.22 for optimized amphiphilicity.

  3. Inclusion Behavior ofβ-Cyclodextrin and Amphiphilic Telechelic Polymer C-PDMAEMA%β-环糊精和遥爪聚合物C-PDMAEMA的包结行为

    Institute of Scientific and Technical Information of China (English)

    江金强; 姜韬; 张成邦; 成浩; 刘晓亚; 张胜文; 陈明清

    2011-01-01

    A novel photosensitive telechelic polymer C-PDMAEMA was prepared using 2-(dimethylamino) ethyl methacrylate (DAMEMA) as a monomer, azobisisobutyronitrile (AIBN) as inititon, coumarin-containing disulfides (C-S-S-C) as a chain transfer agent in the presence of tributyl phosphine (Bu3P) and water. Characterization was carried out using 1H-nuclear magnetic responance (1H-NMR), gel permeation chromatography (GPC) and Fourier transform infrared (FTIR) spectroscopy. It was found that the coumarin can form a host-guest inclusion complex with j8-CD in aqueous solution. The UV-Vis and fluorescence spectra showed that only a 1:1 complex was formed with an inclusion complex K=(1.270±0.062)x104L? Mol"1. The irradiation experiment showed that this host-guest inclusion might have a very small effect on the photodimerization of coumarin end groups.%以香豆素二硫化物(C-S-S-C)/三丁基膦(Bu3P)复合体系为链转移剂,甲基丙烯酸-N,N-二甲氨基乙酯(DMAEMA)为单体,偶氮二异丁腈(AIBN)为引发剂制备了末端为香豆素光响应基元的双亲性遥爪聚合物(C-PDMAEMA).用傅里叶变换红外(FTIR)光谱仪、凝胶渗透色谱(GPC)、核磁共振氢谱(1H-NMR)等对该聚合物进行了结构表征.并用紫外-可见吸收光谱和荧光光谱及光二聚反应考察了β-环糊精与香豆素端基的包结络合行为.研究表明:β-环糊精与香豆素端基足以1∶1形式进行包结,其包结常数K=(1.270+0.062)x104 L·mol-1;光二聚反应实验表明该包结络合作用处于一快速平衡中,其对香豆素端基光二聚反应的影响甚微.

  4. Bone Anchored Hearing Treatment Procedure

    Medline Plus

    Full Text Available ... skin to allow removal of some of the soft tissue where the screwlike fixture will be anchored. The ... screen, acting as a hinge. Beneath that the soft tissue consisting of fat and some muscle is removed. ...

  5. Bone Anchored Hearing Treatment Procedure

    Medline Plus

    Full Text Available ... The Baha system consists of a bone-anchored titanium fixture that is implanted in the mastoid bone, ... the -- great. I'm going to grab the titanium implant. And what I want you to notice ...

  6. Anchoring: A "Cure" for Epy.

    Science.gov (United States)

    Thalgott, Mary R.

    1986-01-01

    Anchoring, a neurolinguistic programing technique, was successful in helping a sixth grader with learning disabilities reduce his anxiety reaction to math tasks. Other uses for the approach are noted and guidelines offered. (CL)

  7. Synthesis of Hydrophilic and Amphiphilic Acryl Sucrose Monomers and Their Copolymerisation with Styrene, Methylmethacrylate and α- and β-Pinenes

    Directory of Open Access Journals (Sweden)

    Maria Teresa Barros

    2010-04-01

    Full Text Available Herein, we report the synthesis of monomethacryloyl sucrose esters, and their successful free radical homo- and co-polymerisation with styrene, methylmethacrylate, α- and β-pinene. The chemical, physical, structural and surface chemical properties of these polymers, containing a hydrophobic olefin backbone and hydrophilic sugar moieties as side chains, have been investigated. Biodegradation tests of the copolymer samples by a microbial fungal culture (Aspergillus niger method showed good biodegradability. The chemical structure and surface chemistry of the synthesized homo- and co-polymers demonstrate their potential technological relevance as amphiphilic and biodegradable polymers.

  8. Synthesis of an amphiphilic dendrimer-like block copolymer and its application on drug delivery

    KAUST Repository

    Wang, Shuaipeng

    2014-10-27

    Dendrimer-like amphiphilic copolymer is a kind of three-dimensional spherical structure polymer. An amphiphilic dendrimer-like diblock copolymer, PEEGE-G2-b-PEO(OH)12, constituted of a hydrophobic poly(ethoxyethyl glycidol ether) inner core and a hydrophilic poly(ethylene oxide) outer layer, has been successfully synthesized by the living anionic ring-opening polymerization method. The intermediates and targeted products were characterized with 1H NMR spectroscopy and gel permeation chromatography. The application on drug delivery of dendrimer-like diblock copolymer PEEGE-G2-b-PEO(OH)12 using DOX as a model drug was also studied. The drug loading content and encapsulation efficiency were found at 13.07% and 45.75%, respectively. In vitro release experiment results indicated that the drug-loaded micelles exhibited a sustained release behavior under acidic media.

  9. Plasmonic Vesicles of Amphiphilic Nanocrystals: Optically Active Multifunctional Platform for Cancer Diagnosis and Therapy.

    Science.gov (United States)

    Song, Jibin; Huang, Peng; Duan, Hongwei; Chen, Xiaoyuan

    2015-09-15

    Vesicular structures with compartmentalized, water-filled cavities, such as liposomes of natural and synthetic amphiphiles, have tremendous potential applications in nanomedicine. When block copolymers self-assemble, the result is polymersomes with tailored structural properties and built-in releasing mechanisms, controlled by stimuli-responsive polymer building blocks. More recently, chemists are becoming interested in multifunctional hybrid vesicles containing inorganic nanocrystals with unique optical, electronic, and magnetic properties. In this Account, we review our recent progress in assembling amphiphilic plasmonic nanostructures to create a new class of multifunctional hybrid vesicles and applying them towards cancer diagnosis and therapy. Localized surface plasmon resonance (LSPR) gives plasmonic nanomaterials a unique set of optical properties that are potentially useful for both biosensing and nanomedicine. For instance, the strong light scattering at their LSPR wavelength opens up the applications of plasmonic nanostructures in single particle plasmonic imaging. Their superior photothermal conversion properties, on the other hand, make them excellent transducers for photothermal ablation and contrast agents for photoacoustic imaging. Of particular note for ultrasensitive detection is that the confined electromagnetic field resulting from excitation of LSPR can give rise to highly efficient surface enhanced Raman scattering (SERS) for molecules in close proximity. We have explored several ways to combine well-defined plasmonic nanocrystals with amphiphilic polymer brushes of diverse chemical functionalities. In multiple systems, we have shown that the polymer grafts impart amphiphilicity-driven self-assembly to the hybrid nanoparticles. This has allowed us to synthesize well-defined vesicles in which we have embedded plasmonic nanocrystals in the shell of collapsed hydrophobic polymers. The hydrophilic brushes extend into external and interior aqueous

  10. Plasmonic Vesicles of Amphiphilic Nanocrystals: Optically Active Multifunctional Platform for Cancer Diagnosis and Therapy.

    Science.gov (United States)

    Song, Jibin; Huang, Peng; Duan, Hongwei; Chen, Xiaoyuan

    2015-09-15

    Vesicular structures with compartmentalized, water-filled cavities, such as liposomes of natural and synthetic amphiphiles, have tremendous potential applications in nanomedicine. When block copolymers self-assemble, the result is polymersomes with tailored structural properties and built-in releasing mechanisms, controlled by stimuli-responsive polymer building blocks. More recently, chemists are becoming interested in multifunctional hybrid vesicles containing inorganic nanocrystals with unique optical, electronic, and magnetic properties. In this Account, we review our recent progress in assembling amphiphilic plasmonic nanostructures to create a new class of multifunctional hybrid vesicles and applying them towards cancer diagnosis and therapy. Localized surface plasmon resonance (LSPR) gives plasmonic nanomaterials a unique set of optical properties that are potentially useful for both biosensing and nanomedicine. For instance, the strong light scattering at their LSPR wavelength opens up the applications of plasmonic nanostructures in single particle plasmonic imaging. Their superior photothermal conversion properties, on the other hand, make them excellent transducers for photothermal ablation and contrast agents for photoacoustic imaging. Of particular note for ultrasensitive detection is that the confined electromagnetic field resulting from excitation of LSPR can give rise to highly efficient surface enhanced Raman scattering (SERS) for molecules in close proximity. We have explored several ways to combine well-defined plasmonic nanocrystals with amphiphilic polymer brushes of diverse chemical functionalities. In multiple systems, we have shown that the polymer grafts impart amphiphilicity-driven self-assembly to the hybrid nanoparticles. This has allowed us to synthesize well-defined vesicles in which we have embedded plasmonic nanocrystals in the shell of collapsed hydrophobic polymers. The hydrophilic brushes extend into external and interior aqueous

  11. 76 FR 30301 - Commercial Acquisition; Anchor Tenancy

    Science.gov (United States)

    2011-05-25

    ... SPACE ADMINISTRATION 48 CFR Part 1812 RIN 2700-AD64 Commercial Acquisition; Anchor Tenancy AGENCY... multi-year anchor tenancy contracts for commercial space goods or services. Anchor Tenancy means ``an.... Background NASA's FAR Supplement currently includes an incorrect statement that anchor tenancy contracts...

  12. Self-Assembly and Hydrogelation of Peptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Wahyudi Priyono Suwarso

    2012-04-01

    Full Text Available Seven peptide amphiphiles were successfully synthesized using solid phase peptide synthesis method. Peptide amphiphiles were characterized using matrix assisted laser desorption/ionization (MALDI. Atomic force microscopy (AFM study showed that peptide amphiphiles having glycine, valine, or proline as linker, self-assembled into 100-200 nm nanofibers structure. According to our research, both peptide amphiphile with positive and negative charges bear similar self-assembly properties. Peptide amphiphile also showed its capability as low molecular weight gelator (LMWG. Peptide amphiphiles bearing C-16 and C-12 as alkyl showed better hydrogelation properties than C-8 alkyl. Five out of seven peptide amphiphiles have minimum gelation concentration (MGC lower than 1% (w/v.

  13. A comparative study of interaction of ibuprofen with biocompatible polymers.

    Science.gov (United States)

    Khan, Iqrar A; Anjum, Kahkashan; Ali, Mohd Sajid; Kabir-ud Din

    2011-11-01

    In this paper we are reporting the interaction of a non-steroidal anti-inflammatory drug ibuprofen (IBF) with various biocompatible polymers. Being amphiphilic, the drug interacts with the polymers similar to the interaction of surfactants and polymers. Therefore, we have considered the polymer-amphiphile interaction approach using conductimetry. The polymers of different charges (cationic, anionic, and nonionic) have been taken for the study. It was found that the critical aggregation concentration (cac) decreases on increasing the polymer concentrations of cationic as well as nonionic polymers whereas it increases for anionic polymers. The results imply that anionic IBF interacts with cationic and nonionic polymers more strongly as compared to the anionic polymers. A possible anionic-anionic repulsion is responsible for the weak interaction of IBF with anionic polymers. On the other side, the critical micelle concentration (cmc) increases for all polymers which is a usual indication of the interaction between amphiphiles and polymers. Free energies of aggregation (ΔG(agg)) and micellization (ΔG(mic)) were also computed with the help of degrees of micelle ionization obtained from the specific conductivity - [IBF] isotherms.

  14. 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

  15. Designing new symmetrical facial oligothiophene amphiphiles

    NARCIS (Netherlands)

    Janeliunas, Dainius; Eelkema, Rienk; Nieto-Ortega, Belén; Ramírez Aguilar, Francisco J; López Navarrete, Juan T; van der Mee, Lars; Stuart, Marc C A; Casado, Juan; van Esch, Jan H

    2013-01-01

    In this study we designed a new class of symmetrical facial oligothiophene amphiphiles, which could be obtained in fewer steps than for previously reported analogues, but still possess the specific substituent sequence to control their backbone curvature. This novel design allows the late-stage intr

  16. Bola-amphiphile self-assembly

    DEFF Research Database (Denmark)

    Svaneborg, Carsten

    2012-01-01

    Bola-amphiphiles are rod-like molecules where both ends of the molecule likes contact with water, while the central part of the molecule dislikes contact with water. What do such molecules do when they are dissolved in water? They self-assemble into micelles. This is a Dissipartive particle dynam...

  17. Peptide Amphiphiles in Corneal Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Martina Miotto

    2015-08-01

    Full Text Available The increasing interest in effort towards creating alternative therapies have led to exciting breakthroughs in the attempt to bio-fabricate and engineer live tissues. This has been particularly evident in the development of new approaches applied to reconstruct corneal tissue. The need for tissue-engineered corneas is largely a response to the shortage of donor tissue and the lack of suitable alternative biological scaffolds preventing the treatment of millions of blind people worldwide. This review is focused on recent developments in corneal tissue engineering, specifically on the use of self-assembling peptide amphiphiles for this purpose. Recently, peptide amphiphiles have generated great interest as therapeutic molecules, both in vitro and in vivo. Here we introduce this rapidly developing field, and examine innovative applications of peptide amphiphiles to create natural bio-prosthetic corneal tissue in vitro. The advantages of peptide amphiphiles over other biomaterials, namely their wide range of functions and applications, versatility, and transferability are also discussed to better understand how these fascinating molecules can help solve current challenges in corneal regeneration.

  18. Wetting of brushes by polymer melts

    OpenAIRE

    Maas, J

    2001-01-01

    The scientific and practical importance of thin polymer films is evident and in many applications polymer films are required. Hence, studying properties of polymer films is relevant. Adsorption of polymer at liquid/solid interfaces can stabilise particles in a matrix. Homopolymers are often used for steric stabilisation of particles although these polymers can also destabilise the system by bridging. Diblock copolymers with one adsorbing (anchor) block and one non-adsorbing (buoy) block may b...

  19. Pull-out behavior of CFRP single-strap ground anchors

    OpenAIRE

    Fan, Haifeng; Keller, Thomas; Vassilopoulos, Anastasios

    2016-01-01

    Pull-out experiments were performed on four carbon fiber-reinforced polymer (CFRP) ground anchors simulating their applications in rock and soil. The CFRP tendons used in these anchors comprise a single-strap end on both the ground and air sides. On the ground side, the single-strap end is embedded in a cylinder of high-strength grout which fits into the borehole. In rock applications, the ground-side anchor can be used directly without additional confinement, while in the case of soil, an ad...

  20. Formation and Mechanism of Superhydrophobic/Hydrophobic Surfaces Made from Amphiphiles through Droplet-Mediated Evaporation-Induced Self-Assembly.

    Science.gov (United States)

    Dong, Fangyuan; Zhang, Mi; Tang, Wai-Wa; Wang, Yi

    2015-04-23

    Superhydrophobic/hydrophobic surfaces have attracted wide attention because of their broad applications in various regions, including coating, textile, packaging, electronic devices, and bioengineering. Many studies have been focused on the fabrication of superhydrophobic/hydrophobic surfaces using natural materials. In this paper, superhydrophobic/hydrophobic surfaces were formed by an amphiphilic natural protein, zein, using electrospinning. Water contact angle (WCA) and scanning electron microscopy (SEM) were used to characterize the hydrophobicity and surface morphology of the electrospun structures. The highest WCA of the zein electrospun surfaces could reach 155.5 ± 1.4°. To further understand the mechanism of superhydrophobic surface formation from amphiphiles using electrospinning, a synthetic amphiphilic polymer was selected, and also, a method similar to electrospinning, spray drying, was tried. The electrospun amphiphilic polymer surface showed a high hydrophobicity with a WCA of 141.4 ± 0.7°. WCA of the spray-dried zein surface could reach 125.3 ± 2.1°. The secondary structures of the zein in the electrospun film and cast-dried film were studied using ATR-FTIR, showing that α-helix to β-sheet transformation happened during the solvent evaporation in the cast drying process but not in the electrospinning process. A formation mechanism was proposed on the basis of the orientation of the amphiphiles during the solvent evaporation of different fabrication methods. The droplet-based or jet-based evaporation during electrospinning and spray drying led to the formation of the superhydrophobic/hydrophobic surface by the accumulation of the hydrophobic groups of the amphiphiles on the surface, while the surface-based evaporation during cast drying led to the formation of the hydrophilic surface by the accumulation of the hydrophilic groups of the amphiphiles on the surface.

  1. C-Anchor for Strengthening the Connection between Adhesively Bonded Laminates and Concrete Substrates

    Directory of Open Access Journals (Sweden)

    Ghani Razaqpur

    2015-11-01

    Full Text Available A new carbon fiber reinforced polymer (CFRP anchor is developed and tested to delay debonding in reinforced concrete (RC beams externally strengthened with FRP laminate/sheet. The C-shape anchor is made from a commercially available CFRP grid. The anchors legs are 95 mm long while the spacing between the legs is adjustable, depending on FRP laminate and beam widths. Nine full scale RC beams, 3.0 m long, 250 mm wide and 400 mm deep, were strengthened with CFRP laminate/sheet, with and without the C-anchor. The main test parameters were the type and amount of FRP laminate and the presence/absence of the anchor. Test results showed that beams with the anchor had generally 5%–10% higher debonding and failure load, and they reached higher deflection at failure than the companion beams without anchors. Although complete separation of the FRP laminate from the concrete was not observed in any of the beams with anchors, there was noticeable slip at failure at one end of the laminate. A significant outcome of the study is that anchors are effective in limiting the extent of debonding along the laminate, thus contributing to the flexural stiffness of the beam by reducing the extent of cracking and limiting the crack width along the beam. Finally, the anchor allowed the FRP to reach or exceed its theoretically allowable strain computed based on the American Concrete Institute (ACI Committee 440 recommendation while in none of the beams without anchors, the FRP reached its theoretically allowable strain.

  2. Microgravity Drill and Anchor System

    Science.gov (United States)

    Parness, Aaron; Frost, Matthew A.; King, Jonathan P.

    2013-01-01

    This work is a method to drill into a rock surface regardless of the gravitational field or orientation. The required weight-on-bit (WOB) is supplied by a self-contained anchoring mechanism. The system includes a rotary percussive coring drill, forming a complete sampling instrument usable by robot or human. This method of in situ sample acquisition using micro - spine anchoring technology enables several NASA mission concepts not currently possible with existing technology, including sampling from consolidated rock on asteroids, providing a bolt network for astronauts visiting a near-Earth asteroid, and sampling from the ceilings or vertical walls of lava tubes and cliff faces on Mars. One of the most fundamental parameters of drilling is the WOB; essentially, the load applied to the bit that allows it to cut, creating a reaction force normal to the surface. In every drilling application, there is a minimum WOB that must be maintained for the system to function properly. In microgravity (asteroids and comets), even a small WOB could not be supported conventionally by the weight of the robot or astronaut. An anchoring mechanism would be needed to resist the reactions, or the robot or astronaut would push themselves off the surface and into space. The ability of the system to anchor itself to a surface creates potential applications that reach beyond use in low gravity. The use of these anchoring mechanisms as end effectors on climbing robots has the potential of vastly expanding the scope of what is considered accessible terrain. Further, because the drill is supported by its own anchor rather than by a robotic arm, the workspace is not constrained by the reach of such an arm. Yet, if the drill is on a robotic arm, it has the benefit of not reflecting the forces of drilling back to the arm s joints. Combining the drill with the anchoring feet will create a highly mobile, highly stable, and highly reliable system. The drilling system s anchor uses hundreds of

  3. Permanent ground anchors: Nicholson design criteria

    Science.gov (United States)

    Nicholson, P. J.; Uranowski, D. D.; Wycliffe-Jones, P. T.

    1982-09-01

    The methods used by Nicholson Construction Company in the design of permanent ground anchors specifically as related to retaining walls are discussed. Basic soil parameters, design concepts, drilling and grouting methods for ground anchors are discussed. Particular emphasis is placed on anchors founded in soil rather than rock formations. Also, soil properties necessary for the proper design of anchored retaining walls are detailed. The second chapter of the report is devoted to a general discussion of retaining wall and anchor design. In addition, a design example of an anchored retaining wall is presented in a step by step manner.

  4. Peptide nanofibers modified with a protein by using designed anchor molecules bearing hydrophobic and functional moieties.

    Science.gov (United States)

    Miyachi, Ayaka; Takahashi, Tsuyoshi; Matsumura, Sachiko; Mihara, Hisakazu

    2010-06-11

    Self-assembly of peptides and proteins is a key feature of biological functions. Short amphiphilic peptides designed with a beta-sheet structure can form sophisticated nanofiber structures, and the fibers are available as nanomaterials for arranging biomolecules. Peptide FI (H-PKFKIIEFEP-OH) self-assembles into nanofibers with a coiled fine structure, as reported in our previous work. We have constructed anchor molecules that have both a binding moiety for the fiber structure and a functional unit capable of capturing target molecules, with the purpose of arranging proteins on the designed peptide nanofibers. Designed anchors containing an alkyl chain as a binding unit and biotin as a functional moiety were found to bind to peptide fibers FI and F2i (H-ALEAKFAAFEAKLA-NH(2)). The surface-exposed biotin moiety on the fibers could capture an anti-biotin antibody. Moreover, hydrophobic dipeptide anchor units composed of iminodiacetate connected to Phe-Phe or Ile-Ile and a peptide composed of six histidine residues connected to biotin could also connect FI peptide fibers to the anti-biotin antibody through the chelation of Ni(2+) ions. This strategy of using designed anchors opens a novel approach to constructing nanoscale protein arrays on peptide nanomaterials. PMID:20419712

  5. Foams Stabilized by Tricationic Amphiphilic Surfactants

    OpenAIRE

    Heerschap, Seth; Marafino, John N.; McKenna, Kristin; Caran, Kevin L.; Feitosa, Klebert

    2015-01-01

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. Novel surfactant architectures with multi-cephalic and multi-tailed molecules have reportedly enhanced their anti-bacterial activity in connection with tail length and the nature of the head group, but their ability to produce and stabilize foam is mostly unknown. Here we report on experiments with tris-cationic, triple-headed, double- a...

  6. Amphiphilic Fullerenes for Biomedical and Optoelectronical Applications

    OpenAIRE

    Witte, Patrick

    2009-01-01

    Fullerenes have an enormous potential in applications to physics and biology. Specifically [60]fullerene with its unique electronic, optical and structural properties has attracted considerable attention for its application in biomedical materials and optoelectronic devices. In this context the selective functionalization of C60, which allows to combine the parent properties with new attributes like water-solubility or amphiphilicity is still a challenging topic for the synthetic chemist. In ...

  7. Prebiotic Lipidic Amphiphiles and Condensing Agents on the Early Earth

    OpenAIRE

    Michele Fiore; Peter Strazewski

    2016-01-01

    It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of ...

  8. Nano-Assemblies of Modified Cyclodextrins and Their Complexes with Guest Molecules: Incorporation in Nanostructured Membranes and Amphiphile Nanoarchitectonics Design

    Directory of Open Access Journals (Sweden)

    Leïla Zerkoune

    2014-08-01

    Full Text Available A variety of cyclodextrin-based molecular structures, with substitutions of either primary or secondary faces of the natural oligosaccharide macrocycles of α-, β-, or γ-cyclodextrins, have been designed towards innovative applications of self-assembled cyclodextrin nanomaterials. Amphiphilic cyclodextrins have been obtained by chemical or enzymatic modifications of their macrocycles using phospholipidyl, peptidolipidyl, cholesteryl, and oligo(ethylene oxide anchors as well as variable numbers of grafted hydrophobic hydrocarbon or fluorinated chains. These novel compounds may self-assemble in an aqueous medium into different types of supramolecular nanoassemblies (vesicles, micelles, nanorods, nanospheres, and other kinds of nanoparticles and liquid crystalline structures. This review discusses the supramolecular nanoarchitectures, which can be formed by amphiphilic cyclodextrin derivatives in mixtures with other molecules (phospholipids, surfactants, and olygonucleotides. Biomedical applications are foreseen for nanoencapsulation of drug molecules in the hydrophobic interchain volumes and nanocavities of the amphiphilic cyclodextrins (serving as drug carriers or pharmaceutical excipients, anticancer phototherapy, gene delivery, as well as for protection of instable active ingredients through inclusion complexation in nanostructured media.

  9. Amphiphilic Cellulose Ethers Designed for Amorphous Solid Dispersion via Olefin Cross-Metathesis.

    Science.gov (United States)

    Dong, Yifan; Mosquera-Giraldo, Laura I; Taylor, Lynne S; Edgar, Kevin J

    2016-02-01

    The design of cellulose ether-based amphiphiles has been difficult and limited because of the harsh conditions typically required for appending ether moieties to cellulose. Olefin cross-metathesis recently has been shown to be a valuable approach for appending a variety of functional groups to cellulose ethers and esters, provided that an olefin handle for metathesis can be attached. This synthetic pathway gives access to these functional derivatives under very mild conditions and at high efficiency. Modification of ethyl cellulose by metathesis to prepare useful derivatives, for example, for solubility and bioavailability enhancement of drugs by amorphous solid dispersion (ASD), has been limited by the low DS(OH) of commercial ethyl cellulose derivatives. This is problematic because ethyl cellulose is otherwise a very attractive substrate for synthesis of amphiphilic derivatives by olefin metathesis. Herein we explore two methods for opening up this design space for ether-based amphiphiles, for example, permitting synthesis of more hydrophilic derivatives. One approach is to start with the more hydrophilic commercial methyl cellulose, which contains much higher DS(OH) and therefore is better suited for introduction of high DS of olefin metathesis "handles". In another approach, we explored a homogeneous one-pot synthesis methodology from cellulose, where controlled DS of ethyl groups was introduced at the same time as the ω-unsaturated alkyl groups, thereby permitting complete control of DS(OH), DS(Et), and ultimately DS of the functional group added by metathesis. We describe the functionalized derivatives available by these successful approaches. In addition, we explore new methods for reduction of the unsaturation in initial metathesis products to provide robust methods for enhancing product stability against further radical-catalyzed reactions. We demonstrate initial evidence that the products show strong promise as amphiphilic matrix polymers for amorphous

  10. Amphiphilic Cellulose Ethers Designed for Amorphous Solid Dispersion via Olefin Cross-Metathesis.

    Science.gov (United States)

    Dong, Yifan; Mosquera-Giraldo, Laura I; Taylor, Lynne S; Edgar, Kevin J

    2016-02-01

    The design of cellulose ether-based amphiphiles has been difficult and limited because of the harsh conditions typically required for appending ether moieties to cellulose. Olefin cross-metathesis recently has been shown to be a valuable approach for appending a variety of functional groups to cellulose ethers and esters, provided that an olefin handle for metathesis can be attached. This synthetic pathway gives access to these functional derivatives under very mild conditions and at high efficiency. Modification of ethyl cellulose by metathesis to prepare useful derivatives, for example, for solubility and bioavailability enhancement of drugs by amorphous solid dispersion (ASD), has been limited by the low DS(OH) of commercial ethyl cellulose derivatives. This is problematic because ethyl cellulose is otherwise a very attractive substrate for synthesis of amphiphilic derivatives by olefin metathesis. Herein we explore two methods for opening up this design space for ether-based amphiphiles, for example, permitting synthesis of more hydrophilic derivatives. One approach is to start with the more hydrophilic commercial methyl cellulose, which contains much higher DS(OH) and therefore is better suited for introduction of high DS of olefin metathesis "handles". In another approach, we explored a homogeneous one-pot synthesis methodology from cellulose, where controlled DS of ethyl groups was introduced at the same time as the ω-unsaturated alkyl groups, thereby permitting complete control of DS(OH), DS(Et), and ultimately DS of the functional group added by metathesis. We describe the functionalized derivatives available by these successful approaches. In addition, we explore new methods for reduction of the unsaturation in initial metathesis products to provide robust methods for enhancing product stability against further radical-catalyzed reactions. We demonstrate initial evidence that the products show strong promise as amphiphilic matrix polymers for amorphous

  11. ANIONIC SYNTHESIS OF A "CLICKABLE" MIDDLE-CHAIN AZIDEFUNCTIONALIZED POLYSTYRENE AND ITS APPLICATION IN SHAPE AMPHIPHILES

    Institute of Scientific and Technical Information of China (English)

    Kan Yue; Jinlin He; Chang Liu; Mingjun Huang; Xue-Hui Dong; Kai Guo; Peihong Ni

    2013-01-01

    "Click chemistry" is,by definition,a general functionalization methodology (GFM) and its marriage with living anionic polymerization is particularly powerful in precise macromolecular synthesis.This paper reports the synthesis of a "clickable" middle-chain azide-functionalized polystyrene (mPS-N3) by anionic polymerization and its application in the preparation of novel shape amphiphiles based on polyhedral oligomeric silsesquioxane (POSS).The mPS-N3 was synthesized by coupling living poly(styryl)lithium chains (PSLi) with 3-chloropropylmethyldichlorosilane and subsequent nucleophilic substitution of the chloro group in the presence of sodium azide.Excess PSLi was end-capped with ethylene oxide to facilitate its removal by flash chromatography.The mPS-N3 was then derived into a giant lipid-like shape amphiphile in two steps following a sequential "click" strategy.The copper(I)-catalyzed azide-alkyne cycloaddition between mPS-N3 and alkyne-functionalized vinyl-substituted POSS derivative (VPOSS-alkyne) ensured quantitative ligation to give polystyrene with VPOSS tethered at the middle of the chain (mPS-VPOSS).The thiol-ene reaction with 1-thioglycerol transforms the vinyl groups on the POSS periphery to hydroxyls,resulting in an amphiphilic shape amphiphile,mPS-DPOSS.This synthetic approach is highly efficient and modular.It demonstrates the "click" philosophy of facile complex molecule construction from a library of simple building blocks and also suggests that mPS-N3 can be used as a versatile "clickable" motif in polymer science for the precise synthesis of complex macromolecules.

  12. 77 FR 65496 - Commercial Acquisition; Anchor Tenancy

    Science.gov (United States)

    2012-10-29

    ... . SUPPLEMENTARY INFORMATION: A. Background NASA published a proposed rule in the Federal Register at 76 FR 30301... SPACE ADMINISTRATION 48 CFR Part 1812 RIN 2700-AD64 Commercial Acquisition; Anchor Tenancy AGENCY... limited conditions, to issue Anchor Tenancy contracts. Anchor Tenancy means ``an arrangement in which...

  13. A redox-responsive mesoporous silica nanoparticle capped with amphiphilic peptides by self-assembly for cancer targeting drug delivery

    Science.gov (United States)

    Xiao, Dong; Jia, Hui-Zhen; Ma, Ning; Zhuo, Ren-Xi; Zhang, Xian-Zheng

    2015-05-01

    A redox-responsive mesoporous silica nanoparticle (RRMSN) was developed as a drug nanocarrier by noncovalent functionalization of MSNs with amphiphilic peptides containing the RGD ligand. The alkyl chain stearic acid (C18) with a thiol terminal group was anchored on the surface of MSNs via a disulfide bond, and the amphiphilic peptide (AP) C18-DSDSDSDSRGDS was coated by self-assembly through hydrophobic interactions between the octadecyl groups of MSNs and alkyl chains of AP, which played the role of a gatekeeper collectively. In vitro drug release profiles demonstrated that the anticancer drug (DOX) could be entrapped with nearly no leakage in the absence of dithiothreitol (DTT) or glutathione (GSH). With the addition of DTT or GSH, the entrapped drug released quickly due to the cleavage of the disulfide bond. It was found that after the internalization of MSNs by cancer cells via the receptor-mediated endocytosis, the surface amphiphilic peptides and alkyl chain of RRMSN/DOX were removed to induce rapid drug release intracellularly after the cleavage of the disulfide bond, triggered by GSH secreted in cancer cells. This novel intelligent RRMSN/DOX drug delivery system using self-assembly of amphiphilic peptides around the MSNs provides a facile, but effective strategy for the design and development of smart drug delivery for cancer therapy.A redox-responsive mesoporous silica nanoparticle (RRMSN) was developed as a drug nanocarrier by noncovalent functionalization of MSNs with amphiphilic peptides containing the RGD ligand. The alkyl chain stearic acid (C18) with a thiol terminal group was anchored on the surface of MSNs via a disulfide bond, and the amphiphilic peptide (AP) C18-DSDSDSDSRGDS was coated by self-assembly through hydrophobic interactions between the octadecyl groups of MSNs and alkyl chains of AP, which played the role of a gatekeeper collectively. In vitro drug release profiles demonstrated that the anticancer drug (DOX) could be entrapped with

  14. Foaming behaviour of polymer-surfactant solutions

    International Nuclear Information System (INIS)

    We study the effect of a non-ionic amphiphilic polymer (PEG-100 stearate also called Myrj 59) on the foaming behaviour of aqueous solutions of an anionic surfactant (sodium dodecyl sulfate or SDS). The SDS concentration was kept fixed while the Myrj 59 concentration was varied. Measurements of foamability, surface tension and electrical conductivity were carried out. The results show two opposite effects depending on the polymer concentration: foamability is higher when the Myrj 59 concentration is low; however, it decreases considerably when the polymer concentration is increased. This behaviour is due to the polymer adsorption at the air/liquid interface at lower polymer concentrations, and to the formation of a polymer-surfactant complex in the bulk at higher concentrations. The results are confirmed by surface tension and electrical conductivity measurements, which are interpreted in terms of the microstructure of the polymer-surfactant solutions. The observed behaviour is due to the amphiphilic nature of the studied polymer. The increased hydrophobicity of Myrj 59, compared to that of water-soluble polymers like PEG or PEO, increases its 'reactivity' towards SDS, i.e. the strength of its interaction with this anionic surfactant. Our results show that hydrophobically modified polymers have potential applications as additives in order to control the foaming properties of surfactant solutions

  15. Perfluorocyclobutyl-containing Amphiphilic Block Copolymers Synthesized by RAFT Polymerization

    Institute of Scientific and Technical Information of China (English)

    LI, Yongjun; ZHANG, Sen; FENG, Chun; ZHANG, Yaqin; LI, Qingnuan; LI, Wenxin; HUANG, Xiaoyu

    2009-01-01

    Amphiphilic block copolymers containing hydrophobic perfluorocyclobutyl-based (PFCB) polyacrylate and hydrophilic poly(ethylene glycol) (PEG) segments were prepared via reversible addition-fragmentation chain transfer (RAP-T) polymerization. The PFCB-containing acrylate monomer, p-(2-(p-tolyloxy)perfluorocyclobutoxy)phenyl acrylate, was first synthesized from commercially available compounds in good yields, and this kind of acrylate monomer can be homopolymerized by free radical polymerization or RAFT polymerization. Kinetic study showed the 2,2'-azobis(isobutyronitrile) (AIBN) initiated and cumyl dithiobenzoate (CDB) mediated RAFT polymerization was in a living fashion, as suggested by the fact that the number-average molecular weights (M_n) increased linearly with the conversions of the monomer, while the polydispersity indices kept less than 1.10. The block polymers with narrow molecular weight distributions (M_w/M_n≤1.21) were prepared through RAFT polymerization using PEG monomethyl ether capped with 4-cyanopentanoic acid dithiobenzoate end group as the macro chain transfer agent (mPEG-CTA). The length of the hydrophobic segment can be tuned by the feed ratio of the PFCB-based acrylate monomer and the extending of the polymerization time. The micellization behavior of the block copolymers in aqueous media was investigated by the fluorescence probe technique.

  16. Effect of Amphiphiles on the Rheology of Triglyceride Networks

    Science.gov (United States)

    Seth, Jyoti

    2014-11-01

    Networks of aggregated crystallites form the structural backbone of many products from the food, cosmetic and pharmaceutical industries. Such materials are generally formulated by cooling a saturated solution to yield the desired solid fraction. Crystal nucleation and growth followed by aggregation leads to formation of a space percolating fractal-network. It is understood that microstructural hierarchy and particle-particle interactions determine material behavior during processing, storage and use. In this talk, rheology of suspensions of triglycerides (TAG, like tristearin) will be explored. TAGs exhibit a rich assortment of polymorphs and form suspensions that are evidently sensitive to surface modifying additives like surfactants and polymers. Here, a theoretical framework will be presented for suspensions containing TAG crystals interacting via pairwise potentials. The work builds on existing models of fractal aggregates to understand microstructure and its correlation with material rheology. Effect of amphiphilic additives is derived through variation of particle-particle interactions. Theoretical predictions for storage modulus will be compared against experimental observations and data from the literature and micro structural predictions against microscopy. Such a theory may serve as a step towards predicting short and long-term behavior of aggregated suspensions formulated via crystallization.

  17. Fluctuations and structure of amphiphilic films; Fluctuations et structure de films d`amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Gourier, CH

    1996-07-01

    This thesis is divided in three parts.The first part exposes in a theoretical point of view, how the fluctuations spectrum of an amphiphilic film is governed by its properties and its bidimensional characteristics.The measurements of fluctuations spectra of an interface are accessible with the measurement of intensity that interface diffuses out of the specular angle, we present in the second chapter the principles of the X rays diffusion by a real interface and see how the diffuse diffusion experiments allow to determine the fluctuations spectrum of an amphiphilic film. The second part is devoted to the different experimental techniques that have allowed to realize the study of fluctuation as well as the structural study.The third part is devoted to experimental results concerning the measurements of fluctuations spectra and to the study of the structure of amphiphilic films. We show that it is possible by using an intense source of X rays (ESRF: European Synchrotron Radiation Facility) to measure the water and amphiphilic films fluctuations spectra until molecular scales. The last chapter is devoted to the structural study and film fluctuations made of di-acetylenic molecules. (N.C.)

  18. Water Diffusion Dependence on Amphiphilic Block Design in (Amphiphilic-Hydrophobic) Diblock Copolymer Membranes.

    Science.gov (United States)

    Dorenbos, Gert

    2016-06-30

    Polyelectrolyte membranes (PEMs) are applied in polyelectrolyte fuel cells (PEFC). The proton conductive pathways within PEMs are provided by nanometer-sized water containing pores. Large-scale application of PEFC requires the production of low-cost membranes with high proton conductivity and therefore good connected pore networks. Pore network formation within four alternative model diblock (hydrophobic_amphiphilic) copolymers in the presence of water is studied by dissipative particle dynamics. Each hydrophobic block contains 50 consecutively connected hydrophobic (A) fragments, and amphiphilic blocks contain 40 hydrophobic A beads and 10 hydrophilic C beads. For one amphiphilic block the C beads are distributed uniformly along the backbone. For the other architectures C beads are located at the end of the side chains attached at regular intervals along the backbone. Water diffusion through the pores is modeled by Monte Carlo tracer diffusion through mapped morphologies. Diffusion is highest for the grafted architectures and increases with increase of length of the side chains. A consistent picture emerges in which diffusion strongly increases with the value of ⟨Nbond⟩ within the amphiphilic block, where ⟨Nbond⟩ is the average number of bonds between hydrophobic A beads and the nearest C bead. PMID:27266679

  19. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hung-Yu; Sheng, Yu-Jane, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan (China); Tu, Sheng-Hung [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan (China); Tsao, Heng-Kwong, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical and Materials Engineering and Department of Physics, National Central University, Jhongli 320, Taiwan (China)

    2014-08-07

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n{sup ′}) motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n{sup ′}-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings.

  20. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles.

    Science.gov (United States)

    Chang, Hung-Yu; Tu, Sheng-Hung; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2014-08-01

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n') motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n'-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings.

  1. Glucose-neopentyl glycol (GNG) amphiphiles for membrane protein study

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Rana, Rohini R; Gotfryd, Kamil;

    2013-01-01

    The development of a new class of surfactants for membrane protein manipulation, "GNG amphiphiles", is reported. These amphiphiles display promising behavior for membrane proteins, as demonstrated recently by the high resolution structure of a sodium-pumping pyrophosphatase reported by Kellosalo et...

  2. Incorporation of Amphiphilic Cyclodextrins into Liposomes as Artificial Receptor Units

    NARCIS (Netherlands)

    Kauscher, Ulrike; Stuart, Marc C. A.; Druecker, Patrick; Galla, Hans-Joachim; Ravoo, Bart Jan

    2013-01-01

    In this article, we describe the introduction of amphiphilic beta-cyclodextrins into liposomes to act as artificial receptor units. Using dynamic light scattering, dye encapsulation, and cryogenic transmission electron microscopy, we show that amphiphilic beta-cyclodextrins can be mixed in any propo

  3. Anchoring in numeric judgments of visual stimuli

    Directory of Open Access Journals (Sweden)

    Linda eLangeborg

    2016-02-01

    Full Text Available This article investigates effects of anchoring in age estimation and estimation of quantities, two tasks which to different extents are based on visual stimuli. The results are compared to anchoring in answers to classic general knowledge questions that rely on semantic knowledge. Cognitive load was manipulated to explore possible differences between domains. Effects of source credibility, manipulated by differing instructions regarding the selection of anchor values (no information regarding anchor selection, information that the anchors are randomly generated or information that the anchors are answers from an expert on anchoring were also investigated. Effects of anchoring were large for all types of judgments but were not affected by cognitive load or by source credibility in either one of the researched domains. A main effect of cognitive load on quantity estimations and main effects of source credibility in the two visually based domains indicate that the manipulations were efficient. Implications for theoretical explanations of anchoring are discussed. In particular, because anchoring did not interact with source credibility or cognitive load, the results imply that the process behind anchoring in visual tasks is predominantly automatic and unconscious.

  4. Inconspicuous anchoring effects generated by false information

    Institute of Scientific and Technical Information of China (English)

    Chen Qu; Jun Wang; Yuejia Luo

    2008-01-01

    The impact of false information on numerical judgments was examined on young normal subjects by an event-related potential (ERP) experiment. To imitate the judgments in real world, we ensured the subjects acknowledged of the target task. The behavioral results found that both uncertain information and false information assimilated the final estimates: higher after higher anchors and lower after lower anchors; and false information caused a weaker anchoring bias than uncertain information. ERP results provided further electrophysiological evidence for the mechanism of anchoring. In the early phrase, it was an accessibility-dominated process in which two kinds of anchors elicited an N300 component related to the accessibility of anchors propositions. The knowledge relevant to targets joined the process in the late phrase, which caused a larger amplitude of late positive component (LPC) for implausible lower anchors than that for plausible higher anchors. Source analysis showed that medial frontal gyrus, whose activity was suggested to signal the need of adjustment, was more reliable to explain the LPC elicited by implausible lower anchors. Therefore, we suggest that accessibility is facilitated when the external anchor is consistent with the world knowledge, and adjustment is initiated when the external anchor is inconsistent.

  5. Anchoring in Numeric Judgments of Visual Stimuli.

    Science.gov (United States)

    Langeborg, Linda; Eriksson, Mårten

    2016-01-01

    This article investigates effects of anchoring in age estimation and estimation of quantities, two tasks which to different extents are based on visual stimuli. The results are compared to anchoring in answers to classic general knowledge questions that rely on semantic knowledge. Cognitive load was manipulated to explore possible differences between domains. Effects of source credibility, manipulated by differing instructions regarding the selection of anchor values (no information regarding anchor selection, information that the anchors are randomly generated or information that the anchors are answers from an expert) on anchoring were also investigated. Effects of anchoring were large for all types of judgments but were not affected by cognitive load or by source credibility in either one of the researched domains. A main effect of cognitive load on quantity estimations and main effects of source credibility in the two visually based domains indicate that the manipulations were efficient. Implications for theoretical explanations of anchoring are discussed. In particular, because anchoring did not interact with cognitive load, the results imply that the process behind anchoring in visual tasks is predominantly automatic and unconscious. PMID:26941684

  6. Anchoring in Numeric Judgments of Visual Stimuli.

    Science.gov (United States)

    Langeborg, Linda; Eriksson, Mårten

    2016-01-01

    This article investigates effects of anchoring in age estimation and estimation of quantities, two tasks which to different extents are based on visual stimuli. The results are compared to anchoring in answers to classic general knowledge questions that rely on semantic knowledge. Cognitive load was manipulated to explore possible differences between domains. Effects of source credibility, manipulated by differing instructions regarding the selection of anchor values (no information regarding anchor selection, information that the anchors are randomly generated or information that the anchors are answers from an expert) on anchoring were also investigated. Effects of anchoring were large for all types of judgments but were not affected by cognitive load or by source credibility in either one of the researched domains. A main effect of cognitive load on quantity estimations and main effects of source credibility in the two visually based domains indicate that the manipulations were efficient. Implications for theoretical explanations of anchoring are discussed. In particular, because anchoring did not interact with cognitive load, the results imply that the process behind anchoring in visual tasks is predominantly automatic and unconscious.

  7. Reactive polymers: part I - Novel polystyrene-anchored copper (II), nickel (II), cobalt (II), iron (III), zinc (II), cadmium (II), molybdenum (VI) and uranium (VI) complexes of the chelating resin containing thiosemicarbazone

    International Nuclear Information System (INIS)

    A new chelating resin containing thiosemicarbazone has been synthesized by the reaction of aldehydopolystyrene and thiosemicarbazide. The polystyrene bound thiosemicarbazone reacts with salicylaldehyde leading to the formation of a new Schiff base chelating resin which reacts with sodium monochloroacetate and gives the polymer bound S-acetatothiosemicarbazone. The new chelating resin forms complexes of the types PS-LCuX·S, PS-LNiX·3S, PS-LHNi(acac)2, PS-LCoX·3S, PS-LFeX2·2S, PS-LZnX·S, PS-LCdX·S, PS-LMoO2(acac) and PS-LUO2X·S (where PS-LH = polymeranchored ligand; S = DMF or CH3OH; X=Cl or CH3COO- and acacH = acetylacetone). The chelating resins and complexes have been characterized by elemental analysis, IR and electronic spectra and magnetic measurements. The Cu(II), Ni(II), Co(II), and Fe(III) complexes are paramagnetic while the Zn(II), Cd(II), Mo(VI) and U(VI) complexes are diamagnetic. The IR data indicate the thioenolization of the ligand in the complexes (except in PS-LHNi(acac)2 where it behaves as a neutral bidentate ligand). (author). 24 refs., 2 tabs

  8. Self-assembly of amphiphilic plasmonic micelle-like nanoparticles in selective solvents.

    Science.gov (United States)

    He, Jie; Huang, Xinglu; Li, Yan-Chun; Liu, Yijing; Babu, Taarika; Aronova, Maria A; Wang, Shouju; Lu, Zhongyuan; Chen, Xiaoyuan; Nie, Zhihong

    2013-05-29

    Amphiphilic plasmonic micelle-like nanoparticles (APMNs) composed of gold nanoparticles (AuNPs) and amphiphilic block copolymers (BCPs) structurally resemble polymer micelles with well-defined architectures and chemistry. The APMNs can be potentially considered as a prototype for modeling a higher-level self-assembly of micelles. The understanding of such secondary self-assembly is of particular importance for the bottom-up design of new hierarchical nanostructures. This article describes the self-assembly, modeling, and applications of APMN assemblies in selective solvents. In a mixture of water/tetrahydrofuran, APMNs assembled into various superstructures, including unimolecular micelles, clusters with controlled number of APMNs, and vesicles, depending on the lengths of polymer tethers and the sizes of AuNP cores. The delicate interplay of entropy and enthalpy contributions to the overall free energy associated with the assembly process, which is strongly dependent on the spherical architecture of APMNs, yields an assembly diagram that is different from the assembly of linear BCPs. Our experimental and computational studies suggested that the morphologies of assemblies were largely determined by the deformability of the effective nanoparticles (that is, nanoparticles together with tethered chains as a whole). The assemblies of APMNs resulted in strong absorption in near-infrared range due to the remarkable plasmonic coupling of Au cores, thus facilitating their biomedical applications in bioimaging and photothermal therapy of cancer.

  9. NOVEL AMPHIPHILIC FLUORESCENT GRAFT COPOLYMER: SYNTHESIS,CHARACTERIZATION AND ENCAPSULATION OF A HYDROPHOBIC AGENT

    Institute of Scientific and Technical Information of China (English)

    Zhao-qiang Wu; Shu Yang; Wen-yan Liao; Ling-zhi Meng

    2006-01-01

    Novel amphiphilic fluorescent graft copolymer (PVP-PyAHy) was successfully synthesized by the free radical copolymerization of hydrophobic monomer N-(1-pyrenebutyryl)-N'-acryloyl hydrazide (PyAHy) with hydrophilic precursor polymers of vinyl-functionalized poly(N-vinylpyrrolidone) (PVP) in DMF. The copolymer is amphiphilic and has intrinsic fluorescence. FT-IR, 1H-NMR, TEM, gel permeation chromatography-multi-angle laser light scattering, UV-Vis spectroscopy and fluorescence spectroscopy were used to characterize this copolymer. The TEM observation shows that the copolymer PVP-PyAHy forms micelles in aqueous solution. Results of fluorometric measurements illustrate that the critical micelle concentration (CMC) value of PVP-PyAHy in aqueous solution is about 0.90 mg/mL. To examine the encapsulation ability of the copolymer in aqueous media, methyl yellow was employed as a model hydrophobic agent. The loading level of the polymer to methyl yellow is 8.8 mg/g. The cytotoxicity assays for Madin Darby Canine Kidney (MDCK) cells shows good biocompatibility of PVP-PyAHy in vitro. These results suggest the potential of this copolymer PVP-PyAHy as drugs delivery carrier and fluorescent tracer.

  10. Amphiphilic block copolymers as flexible membrane materials generating structural and functional mimics of green bacterial antenna complexes.

    Science.gov (United States)

    Collins, A M; Timlin, J A; Anthony, S M; Montaño, G A

    2016-08-11

    We describe the ability of a short-chain amphiphilic block copolymer to self-assemble to form an artificial supramolecular light-harvesting system. Specifically, we demonstrate that the 2.5 kDa, poly(ethylene oxide)-block-poly(butadiene) (PEO-b-PBD), exhibits sufficient morphological flexibility as a membrane material and enables generation of mimics of three-dimensional chlorosomes as well as supported membrane bilayers containing energy acceptors. This overall architecture replicates green bacterial light-harvesting function whereby these assemblies exhibit long-range order and three-dimensional morphology similar to native chlorosomes and are capable of energy transfer internally and to external acceptors, located in a supporting biomimetic polymer membrane. Unlike native green bacterial systems that use multiple lipids as a matrix to generate the appropriate environment for chlorosome assembly and function, the described system matrix is comprised entirely of a single polymer amphiphile. This work demonstrates the potential of short-chain amphiphilic block copolymers in generating self-assembled, bio-mimetic membrane architectures, and in doing so, generates scalable, spatial-energetic landscapes for photonic applications. Finally, the results presented provide evidence of minimal requirements to induce chlorosome-like organization and function. PMID:27481550

  11. Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier.

    Science.gov (United States)

    Zhao, Yamei; Tian, Wei; Yang, Guang; Fan, Xiaodong

    2014-01-01

    In this paper, a novel, multifunctional polymer nanocarrier was designed to provide adequate volume for high drug loading, to afford a multiregion encapsulation ability, and to achieve controlled drug release. An amphiphilic, triblock polymer (ABC) with hyperbranched polycarbonsilane (HBPCSi) and β-cyclodextrin (β-CD) moieties were first synthesized by the combination of a two-step reversible addition-fragmentation transfer polymerization into a pseudo-one-step hydrosilylation and quaternization reaction. The ABC then self-assembled into stable micelles with a core-shell structure in aqueous solution. These resulting micelles are multifunctional nanocarriers which possess higher drug loading capability due to the introduction of HBPCSi segments and β-CD moieties, and exhibit controlled drug release based on the diffusion release mechanism. The novel multifunctional nanocarrier may be applicable to produce highly efficient and specialized delivery systems for drugs, genes, and diagnostic agents. PMID:25550733

  12. Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier

    Directory of Open Access Journals (Sweden)

    Yamei Zhao

    2014-11-01

    Full Text Available In this paper, a novel, multifunctional polymer nanocarrier was designed to provide adequate volume for high drug loading, to afford a multiregion encapsulation ability, and to achieve controlled drug release. An amphiphilic, triblock polymer (ABC with hyperbranched polycarbonsilane (HBPCSi and β-cyclodextrin (β-CD moieties were first synthesized by the combination of a two-step reversible addition-fragmentation transfer polymerization into a pseudo-one-step hydrosilylation and quaternization reaction. The ABC then self-assembled into stable micelles with a core–shell structure in aqueous solution. These resulting micelles are multifunctional nanocarriers which possess higher drug loading capability due to the introduction of HBPCSi segments and β-CD moieties, and exhibit controlled drug release based on the diffusion release mechanism. The novel multifunctional nanocarrier may be applicable to produce highly efficient and specialized delivery systems for drugs, genes, and diagnostic agents.

  13. Effect of nanoconfinement on polymer dynamics: surface layers and interphases.

    Science.gov (United States)

    Krutyeva, M; Wischnewski, A; Monkenbusch, M; Willner, L; Maiz, J; Mijangos, C; Arbe, A; Colmenero, J; Radulescu, A; Holderer, O; Ohl, M; Richter, D

    2013-03-01

    We present neutron spin echo experiments that address the much debated topic of dynamic phenomena in polymer melts that are induced by interacting with a confining surface. We find an anchored surface layer that internally is highly mobile and not glassy as heavily promoted in the literature. The polymer dynamics in confinement is, rather, determined by two phases, one fully equal to the bulk polymer and another that is partly anchored at the surface. By strong topological interaction, this phase confines further chains with no direct contact to the surface. These form the often invoked interphase, where the full chain relaxation is impeded through the interaction with the anchored chains. PMID:23521308

  14. Amphiphilic polymeric micelle as pseudostationary phase in electrokinetic chromatography for analysis of eight corticosteroids in cosmetics.

    Science.gov (United States)

    Xu, Xiaojin; Ni, Xinjiong; Cao, Yuhua; Zhuo, Xiaolu; Yang, Xiaoxiao; Cao, Guangqun

    2014-03-01

    Amphiphilic polymeric micelle, as a novel pseudostationary phase in EKC was used to determine eight kinds of corticosteroids namely hydrocortisone, prednisolone, hydrocortisone acetate, prednisone, cortisone acetate, prednisolone acetate, dexamethasone, and triamcinolone acetonide in cosmetics. Amphiphilic random copolymer poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) was micellizated via neutralization in alkaline aqueous solution. The influences of the molar ratio of monomer MMA to MAA, the concentration of polymer and pH on the polymeric micelle microstructure and EKC performances were investigated. As molar ratio of MMA to MAA in P(MMA-co-MAA) increased, both CMC and environmental polarity of the inner core in polymeric micelle decreased dramatically. With increasing monomer ratio, the size of polymeric micelles increased firstly, and then decreased, finally increased again. ζ potential of the micelle had a slight decline trend. As increment of polymer concentration, the size of the polymeric micelle increased steadily. By optimizing the monomer ratio, the polymer concentration, and pH of the running buffer, as well as operation conditions such as separation voltage and temperature, the eight analytes could be separated within 16.5 min using 7.5 mg/mL polymer with the monomer ratio of 7:3 dissolved in pH 9.2 borax buffer as the running buffer. The method has been used for analysis of corticosteroids in cosmetic samples with simple extraction; the recoveries for eight analytes were between 85.9 and 106%. This method was of accuracy, repeatability, pretreatment simplicity, and could be applied to the quality control of cosmetics. PMID:24338855

  15. Amphiphilic polymeric micelle as pseudostationary phase in electrokinetic chromatography for analysis of eight corticosteroids in cosmetics.

    Science.gov (United States)

    Xu, Xiaojin; Ni, Xinjiong; Cao, Yuhua; Zhuo, Xiaolu; Yang, Xiaoxiao; Cao, Guangqun

    2014-03-01

    Amphiphilic polymeric micelle, as a novel pseudostationary phase in EKC was used to determine eight kinds of corticosteroids namely hydrocortisone, prednisolone, hydrocortisone acetate, prednisone, cortisone acetate, prednisolone acetate, dexamethasone, and triamcinolone acetonide in cosmetics. Amphiphilic random copolymer poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) was micellizated via neutralization in alkaline aqueous solution. The influences of the molar ratio of monomer MMA to MAA, the concentration of polymer and pH on the polymeric micelle microstructure and EKC performances were investigated. As molar ratio of MMA to MAA in P(MMA-co-MAA) increased, both CMC and environmental polarity of the inner core in polymeric micelle decreased dramatically. With increasing monomer ratio, the size of polymeric micelles increased firstly, and then decreased, finally increased again. ζ potential of the micelle had a slight decline trend. As increment of polymer concentration, the size of the polymeric micelle increased steadily. By optimizing the monomer ratio, the polymer concentration, and pH of the running buffer, as well as operation conditions such as separation voltage and temperature, the eight analytes could be separated within 16.5 min using 7.5 mg/mL polymer with the monomer ratio of 7:3 dissolved in pH 9.2 borax buffer as the running buffer. The method has been used for analysis of corticosteroids in cosmetic samples with simple extraction; the recoveries for eight analytes were between 85.9 and 106%. This method was of accuracy, repeatability, pretreatment simplicity, and could be applied to the quality control of cosmetics.

  16. Aqueous Foam Stabilized by Tricationic Amphiphilic Surfactants

    Science.gov (United States)

    Heerschap, Seth; Marafino, John; McKenna, Kristin; Caran, Kevin; Feitosa, Klebert; Kevin Caran's Research Group Collaboration

    2015-03-01

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. The development of novel architectures with multi-cephalic/tailed molecules have enhanced their anti-bacterial activity in connection with tail length and the nature of the head group. Here we report on the foamability of two triple head double, tail cationic surfactants (M-1,14,14, M-P, 14,14) and a triple head single tail cationic surfactant (M-1,1,14) and compare them with commercially available single headed, single tailed anionic and cationic surfactants (SDS,CTAB and DTAB). The results show that bubble rupture rate decrease with the length of the carbon chain irrespective of head structure. The growth rate of bubbles with short tailed surfactants (SDS) and longer, single tailed tricationic surfactants (M-1,1,14) was shown to be twice as high as those with longer tailed surfactants (CTAB, M-P,14,14, M-1,14,14). This fact was related to the size variation of bubbles, where the foams made with short tail surfactants exhibited higher polydispersivity than those with short tails. This suggests that foams with tricationic amphiphilics are closed linked to their tail length and generally insensitive to their head structure.

  17. The Behavior of Amphiphile at Oil-Water Interface by Monte Carlo Simulation

    Institute of Scientific and Technical Information of China (English)

    潘海华; 李啸风; 李浩然; 刘迪霞; 韩世钧

    2003-01-01

    A novel simple two-dimensional square-lattice model of amphiphile at oil-water interface is developed,in which oil and water act as solvent and occupy empty sites and amphiphile occupies chains of sites. In this model, the oil-water interface is fixed, And amphiphile molecules will be enriched at the oil-water interface. The interfacial concentration of amphiphile calculated by Monte Carlo method shows that it is easier for the hydrophilic-hydrophobic balanced amphiphile to stay at the interface. And the adsorption of amphiphile increases with the increase of amphiphile concentration and the decrease with temperature.

  18. MOLECULAR DESIGN OF FUNCTIONAL POLYMERS BASED ON UNIQUE PROPERTIES OF POLYMER CHAINS

    Institute of Scientific and Technical Information of China (English)

    Mikiharu Kamachi

    2000-01-01

    The inclusion complex formation of α-CD, β-CD, and γ-CD with various water-soluble polymers has been investigated, and the relationship between the chain cross-sectional areas of the polymers and the diameters of the cavities of cyclodextrins (molecular recognition) was found. Polyrotaxanes and tubular polymers were prepared on the basis of molecular recognition. Several kinds of polymers having tetraphenylporphyrin (TPP) and paramagnetic metallotetraphenylporphyrin (AgTPP, CuTPP, VOTPP or ZnTPP) have been prepared by radical polymerization of the corresponding monomers. Visible spectra of these polymers show hypochromism in the Soret bands of TPP moieties as compared with those of monomers. Polymer effects were observed in the magnetic behavior and oxygen adsorption of paramagnetic metallotetraphenylporphyrin moieties. Moreover, polymer effects on photophysical and photochemical behavior were found in the amphiphilic polymers covalently tethered with small amounts of zinc(Ⅱ)-tetraphenylporphyrin (ZnTPP).

  19. Aggregation and self-assembly of amphiphilic block copolymers in aqueous dispersions of carbon nanotubes.

    Science.gov (United States)

    Shvartzman-Cohen, Rina; Florent, Marc; Goldfarb, Daniella; Szleifer, Igal; Yerushalmi-Rozen, Rachel

    2008-05-01

    The self-assembly (SA) of amphiphilic block copolymers (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)) was investigated in dispersions of single-walled and multiwalled carbon nanotubes (SWNT and MWNT, respectively) as a function of temperature. Differential scanning calorimetry (DSC) was used for characterization of the thermal behavior of the combined polymers-nanostructures system, and spin-probe electron paramagnetic resonance (EPR) was employed for probing the local dynamic and polarity of the polymer chains in the presence of nanostructures. It was found that SWNT and MWNT modify the temperature, enthalpy, and dynamic behavior of polymer SA. In particular, SWNT were found to increase the cooperativity of aggregating chains and dominate aggregate dynamics. MWNT reduced the cooperativity, while colloidal carbon black additives, studied for comparison, did not show similar effects. The experimental observations are consistent with the suggestion that dimensional matching between the characteristic radius of the solvated polymer chains and the dimensions of additives dominate polymer SA in the hybrid system. PMID:18355098

  20. Shifting Nominal Anchors: The Experience of Mexico

    OpenAIRE

    Leonardo Leiderman; Nissan Liviatan; Alfredo Thorne

    1995-01-01

    In the mid-1980’s Mexico successfully brought down its high rate of inflation by using the exchange rate as nominal anchor in combination with strict fiscal discipline, tight monetary policy, and incomes policy. This paper discusses the role of exchange rate policy as nominal anchor in Mexico and develops the inflation target as the monetary framework for anchoring prices. It also describes how Mexico is applying this frame work while shifting to a more flexible exchange regime and discusses ...

  1. A lunar/Martian anchor emplacement system

    Science.gov (United States)

    Clinton, Dustin; Holt, Andrew; Jantz, Erik; Kaufman, Teresa; Martin, James; Weber, Reed

    On the Moon or Mars, it is necessary to have an anchor, or a stable, fixed point able to support the forces necessary to rescue a stuck vehicle, act as a stake for a tent in a Martian gale, act as a fulcrum in the erection of general construction poles, or support tent-like regolith shields. The anchor emplacement system must be highly autonomous. It must supply the energy and stability for anchor deployment. The goal of the anchor emplacement system project is to design and build a prototype anchor and to design a conceptual anchor emplacement system. Various anchors were tested in a 1.3 cubic meter test bed containing decomposed granite. A simulated lunar soil was created by adjusting the moisture and compaction characteristics of the soil. We conducted tests on emplacement torque, amount of force the anchor could withstand before failure, anchor pull out force at various angles, and soil disturbances caused by placing the anchor. A single helix auger anchor performed best in this test bed based on energy to emplace, and the ultimate holding capacity. The anchor was optimized for ultimate holding capacity, minimum emplacement torque, and minimum soil disturbance in sandy soils yielding the following dimensions: helix diameter (4.45 cm), pitch (1.27 cm), blade thickness (0.15 cm), total length (35.56 cm), shaft diameter (0.78 cm), and a weight of 212.62 g. The experimental results showed that smaller diameter, single-helix augers held more force than larger diameter augers for a given depth. The emplacement system consists of a flywheel and a motor for power, sealed in a protective box supported by four legs. The flywheel system was chosen over a gear system based on its increased reliability in the lunar environment.

  2. Capital Asset Pricing Model Adjusted for Anchoring

    OpenAIRE

    Hammad, Siddiqi

    2015-01-01

    I show that adjusting CAPM for anchoring provides a unified explanation for the size, value, and momentum effects. Anchoring adjusted CAPM (ACAPM) predicts that stock splits are associated with positive abnormal returns and an increase in return volatility, whereas the reverse stock-splits are associated with negative abnormal returns and a fall in return volatility. Existing empirical evidence strongly supports these predictions. Anchoring has the effect of pushing up the equity premium, a ...

  3. Anchored Lagrangian submanifolds and their Floer theory

    CERN Document Server

    Fukaya, Kenji; Ohta, Hiroshi; Ono, Kaoru

    2009-01-01

    We introduce the notion of (graded) anchored Lagrangian submanifolds and use it to study the filtration of Floer' s chain complex. We then obtain an anchored version of Lagrangian Floer homology and its (higher) product structures. They are somewhat different from the more standard non-anchored version. The anchored version discussed in this paper is more naturally related to the variational picture of Lagrangian Floer theory and so to the likes of spectral invariants. We also discuss rationality of Lagrangian submanifold and reduction of the coefficient ring of Lagrangian Floer cohomology of thereof.

  4. Fixation of a human rib by an intramedullary telescoping splint anchored by bone cement.

    Science.gov (United States)

    Liovic, Petar; Šutalo, Ilija D; Marasco, Silvana F

    2016-09-01

    A novel concept for rib fixation is presented that involves the use of a bioresorbable polymer intramedullary telescoping splint. Bone cement is used to anchor each end of the splint inside the medullary canal on each side of the fracture site. In this manner, rib fixation is achieved without fixation device protrusion from the rib, making the splint completely intramedullary. Finite element analysis is used to demonstrate that such a splint/cement composite can preserve rib fixation subjected to cough-intensity force loadings. Computational fluid dynamics and porcine rib experiments were used to study the anchor formation process required to complete the fixation. PMID:26733094

  5. A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion

    Directory of Open Access Journals (Sweden)

    William Gibbons

    2013-04-01

    Full Text Available One of the concerns for economical production of ethanol from biomass is the large volume and high cost of the cellulolytic enzymes used to convert biomass into fermentable sugars. The presence of acetyl groups in hemicellulose and lignin in plant cell walls reduces accessibility of biomass to the enzymes and makes conversion a slow process. In addition to low enzyme accessibility, a rapid deactivation of cellulases during biomass hydrolysis can be another factor contributing to the low sugar recovery. As of now, the economical reduction in lignin content of the biomass is considered a bottleneck, and raises issues for several reasons. The presence of lignin in biomass reduces the swelling of cellulose fibrils and accessibility of enzyme to carbohydrate polymers. It also causes an irreversible adsorption of the cellulolytic enzymes that prevents effective enzyme activity and recycling. Amphiphiles, such as surfactants and proteins have been found to improve enzyme activity by several mechanisms of action that are not yet fully understood. Reduction in irreversible adsorption of enzyme to non-specific sites, reduction in viscosity of liquid and surface tension and consequently reduced contact of enzyme with air-liquid interface, and modifications in biomass chemical structure are some of the benefits derived from surface active molecules. Application of some of these amphiphiles could potentially reduce the capital and operating costs of bioethanol production by reducing fermentation time and the amount of enzyme used for saccharification of biomass. In this review article, the benefit of applying amphiphiles at various stages of ethanol production (i.e., pretreatment, hydrolysis and hydrolysis-fermentation is reviewed and the proposed mechanisms of actions are described.

  6. Uplift of Symmetrical Anchor Plates by Using Grid-Fixed Reinforced Reinforcement in Cohesionless Soil

    Institute of Scientific and Technical Information of China (English)

    Hamed Niroumand; Khairul Anuar Kassim

    2014-01-01

    Uplift response of symmetrical anchor plates with and without grid fixed reinforced (GFR) reinforcement was evaluated in model tests and numerical simulations by Plaxis. Many variations of reinforcement layers were used to reinforce the sandy soil over symmetrical anchor plates. In the current research, different factors such as relative density of sand, embedment ratios, and various GFR parameters including size, number of layers, and the proximity of the layer to the symmetrical anchor plate were investigated in a scale model. The failure mechanism and the associated rupture surface were observed and evaluated. GFR, a tied up system made of fiber reinforcement polymer (FRP) strips and end balls, was connected to the geosynthetic material and anchored into the soil. Test results showed that using GFR reinforcement significantly improved the uplift capacity of anchor plates. It was found that the inclusion of one layer of GFR, which rested directly on the top of the anchor plate, was more effective in enhancing the anchor capacity itself than other methods. It was found that by including GFR the uplift response was improved by 29%. Multi layers of GFR proved more effective in enhancing the uplift capacity than a single GFR reinforcement. This is due to the additional anchorage provided by the GFR at each level of reinforcement. In general, the results show that the uplift capacity of symmetrical anchor plates in loose and dense sand can be significantly increased by the inclusion of GFR. It was also observed that the inclusion of GFR reduced the requirement for a large L/D ratio to achieve the required uplift capacity. The laboratory and numerical analysis results are found to be in agreement in terms of breakout factor and failure mechanism pattern.

  7. Facially amphiphilic thiol capped gold and silver nanoparticles

    OpenAIRE

    Bhat, Shreedhar; Maitra, Uday

    2008-01-01

    A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article.

  8. Facially amphiphilic thiol capped gold and silver nanoparticles

    Indian Academy of Sciences (India)

    Shreedhar Bhata; Uday Maitra

    2008-11-01

    A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article.

  9. Rational design of purely peptidic amphiphiles for drug delivery applications

    OpenAIRE

    Bruyn Ouboter, Dirk de

    2011-01-01

    A broad range of new properties is emerging from supramolecular aggregates. Self-assembled structures of purely peptidic amphiphiles exploit these properties to produce biocompatible, biodegradable, smart materials for drug administration. This thesis explores the design, synthesis, purification, characterization of purely peptidic amphiphiles, and evaluates potential applications. The first chapter provides a general introduction to the field of self-assembly, and of drug delivery as com...

  10. Observed Score Equating Using a Mini-Version Anchor and an Anchor with Less Spread of Difficulty: A Comparison Study

    Science.gov (United States)

    Liu, Jinghua; Sinharay, Sandip; Holland, Paul; Feigenbaum, Miriam; Curley, Edward

    2011-01-01

    Two different types of anchors are investigated in this study: a mini-version anchor and an anchor that has a less spread of difficulty than the tests to be equated. The latter is referred to as a midi anchor. The impact of these two different types of anchors on observed score equating are evaluated and compared with respect to systematic error…

  11. Phase behavior and rheological analysis of reverse liquid crystals and W/I2, W/H2 gel emulsions using an amphiphilic block copolymer.

    OpenAIRE

    May Masnou, Anna; Aramaki, Kenji; Gutiérrez González, José María, 1953-

    2011-01-01

    This article reports the phase behavior determi- nation of a system forming reverse liquid crystals and the formation of novel disperse systems in the two-phase region. The studied system is formed by water, cyclohexane, and Pluronic L-121, an amphiphilic block copolymer considered of special interest due to its aggregation and structural proper- ties. This system forms reverse cubic (I2) and reverse hexagonal (H2) phases at high polymer concentrations. These reverse phases are of particular ...

  12. Amphiphilic poly{[α-maleic anhydride-ω-methoxypoly(ethylene glycol)]-co-(ethyl cyanoacrylate)} graft copolymer nanoparticles as carriers for transdermal drug delivery

    OpenAIRE

    Dong, Anjie

    2009-01-01

    Jinfeng Xing, Liandong Deng, Jun Li, Anjie DongDepartment of Polymer Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, People’s Republic of ChinaAbstract: In this study, the transdermal drug delivery properties of D,L-tetrahydropalmatine (THP)-loaded amphiphilic poly{[α-maleic anhydride-ω-methoxy-poly(ethylene glycol)]-co-(ethyl cyanoacrylate)} (PEGECA) graft copolymer nanoparticles (PEGECAT NPs) were evaluated b...

  13. Link Anchors in Images: Is there Truth?

    NARCIS (Netherlands)

    Aly, Robin; McGuinness, Kevin; Kleppe, Martijn; Ordelman, Roeland; O'Connor, Noel; Jong, de Franciska

    2012-01-01

    While automatic linking in text collections is well understood, little is known about links in images. In this work, we investigate two aspects of anchors, the origin of a link, in images: 1) the requirements of users for such anchors, e.g. the things users would like more information on, and 2) pos

  14. Method of fabrication of anchored nanostructure materials

    Science.gov (United States)

    Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

    2013-11-26

    Methods for fabricating anchored nanostructure materials are described. The methods include heating a nano-catalyst under a protective atmosphere to a temperature ranging from about 450.degree. C. to about 1500.degree. C. and contacting the heated nano-catalysts with an organic vapor to affix carbon nanostructures to the nano-catalysts and form the anchored nanostructure material.

  15. Anchors of Religious Commitment in Adolescents

    Science.gov (United States)

    Layton, Emily; Dollahite, David C.; Hardy, Sam A.

    2011-01-01

    This study explores adolescent religious commitment using qualitative data from a religiously diverse (Jewish, Christian, Muslim) sample of 80 adolescents. A new construct, "anchors of religious commitment," grounded in interview data, is proposed to describe what adolescents commit to as a part of their religious identity. Seven anchors of…

  16. Anchoring of proteins to lactic acid bacteria

    NARCIS (Netherlands)

    Leenhouts, K; Buist, Girbe; Kok, Jan

    1999-01-01

    The anchoring of proteins to the cell surface of lactic acid bacteria (LAB) using genetic techniques is an exciting and emerging research area that holds great promise for a wide variety of biotechnological applications. This paper reviews five different types of anchoring domains that have been exp

  17. Suction anchors for floating production systems

    Energy Technology Data Exchange (ETDEWEB)

    Tjelta, T.I.; Rusas, P. [Statoil a.s. (Norway); Edvardsen, G. [HEX a.s. (Norway)

    1996-12-31

    Since the suction anchor is a recent development in its current use, this work provides a brief historical background. It is shown that the suction anchor throughout evolution today is a competitive foundation solution for many applications. Examples from these categories are included in this paper. Also several installation methods are discussed. 3 refs., 7 figs., 2 tabs.

  18. Wetting in mixtures of water, nonionic amphiphiles, and nonpolar solvents

    Science.gov (United States)

    Kahlweit, M.; Busse, G.

    1989-07-01

    As is well known, medium- and long-chain alkanes do not spread across H2O-air interfaces, but shape a lens. In this paper it is shown that the same holds for the upper amphiphile-rich phase in binary H2O-amphiphile mixtures with medium- and long-chain nonionic amphiphiles that show a (closed) miscibility gap with water. This finding is somewhat unexpected because surfactants form monolayers at H2O-air interfaces which should facilitate the spreading of the amphiphile-rich phase. This wetting behavior corresponds to that in ternary H2O-oil-nonionic amphiphile mixtures with a three-phase body, in which the middle amphiphile-rich phase does not spread across the H2O-oil interface. The results may stimulate further studies on critical-point wetting [for a recent review see, e.g., S. Dietrich, in Phase Transitions and Critical Phenomena, edited by C. Domb and J. L. Lebowitz (Academic, London, 1988), Vol. 12, p. 1.], and may also help clarifying the properties of microemulsions [for a recent review see, e.g., M. Kahlweit, R. Strey, P. Firman, D. Haase, J. Jen, and R. Schomäcker, Langmuir 4, 499 (1988)].

  19. Conductive polymer nanocomposites with hierarchical multi-scale structures via self-assembly of carbon-nanotubes on graphene on polymer-microspheres

    Science.gov (United States)

    Tang, Changyu; Long, Gucheng; Hu, Xin; Wong, Ka-Wai; Lau, Woon-Ming; Fan, Meikun; Mei, Jun; Xu, Tao; Wang, Bin; Hui, David

    2014-06-01

    A novel and highly conductive 3-dimensional (3D) hierarchical multi-scale structure is formed by a new, simple, facile, and water-based method that enables practical production of conductive carbon nanofiller/polymer composites. More specifically, the π-π interaction between CNTs and graphene oxide (GO) is exploited to disperse conductive but non-polar CNTs with amphiphilic GO sheets to form a stable aqueous colloidal solution. Aqueous-dispersible latex-polystyrene microspheres are then added to enable the self-assembly processes of anchoring CNTs on GO and wrapping microspheres with GO-stabilized CNTs for the formation of an intriguing 3D hierarchical multi-scale structure. During this process, GO is reduced to conductive reduced-graphene oxide (RGO). The resultant RGO sheets act as ``nano-walls'' to prevent CNTs from randomly diffusing into the polymer bulk during thermal pressing of RGO-CNT/microspheres, which results in the formation of a 3D foam-like network of RGO-CNTs with high quality. The resultant composite with such a structure gives an ultra-low percolation threshold (0.03 vol% RGO-CNTs) and a reasonably high conductivity (153 S m-1 at 4 vol% RGO-CNTs), which could satisfy various applications requiring both transparency and electrical conduction characteristics (e.g. transparent antistatic coatings, capacitive touch-screens, and transparent electronic devices).A novel and highly conductive 3-dimensional (3D) hierarchical multi-scale structure is formed by a new, simple, facile, and water-based method that enables practical production of conductive carbon nanofiller/polymer composites. More specifically, the π-π interaction between CNTs and graphene oxide (GO) is exploited to disperse conductive but non-polar CNTs with amphiphilic GO sheets to form a stable aqueous colloidal solution. Aqueous-dispersible latex-polystyrene microspheres are then added to enable the self-assembly processes of anchoring CNTs on GO and wrapping microspheres with GO

  20. Polydispersity-Driven Block Copolymer Amphiphile Self-Assembly into Prolate-Spheroid Micelles

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Andrew L.; Repollet-Pedrosa, Milton H.; Mahanthappa, Mahesh K. (UW)

    2013-09-26

    The aqueous self-assembly behavior of polydisperse poly(ethylene oxide-b-1,4-butadiene-b-ethylene oxide) (OBO) macromolecular triblock amphiphiles is examined to discern the implications of continuous polydispersity in the hydrophobic block on the resulting aqueous micellar morphologies of otherwise monodisperse polymer surfactants. The chain length polydispersity and implicit composition polydispersity of these samples furnishes a distribution of preferred interfacial curvatures, resulting in dilute aqueous block copolymer dispersions exhibiting coexisting spherical and rod-like micelles with vesicles in a single sample with a O weight fraction, w{sub O}, of 0.18. At higher w{sub O} = 0.51-0.68, the peak in the interfacial curvature distribution shifts and we observe the formation of only American football-shaped micelles. We rationalize the formation of these anisotropically shaped aggregates based on the intrinsic distribution of preferred curvatures adopted by the polydisperse copolymer amphiphiles and on the relief of core block chain stretching by chain-length-dependent intramicellar segregation.

  1. Ringstone anchors from Gujarat, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Sundaresh; Tripati, S.; Bandodkar, S.N.

    of Dwarka and Somanath have yielded several ringstone anchors along with other stone anchors such as triangular and grapnel types. The raw material used for these ring stones comprises basalt, sandstone and limestone. Earlier, these anchors were identified...

  2. Self-Assembly of Amphiphilic Block Copolypeptoids with C 2 -C 5 Side Chains in Aqueous Solution

    KAUST Repository

    Fetsch, Corinna

    2014-12-22

    © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Nowadays, amphiphilic molecules play an important role in our life. In medical applications, amphiphilic block copolymers have attracted much attention as excipients in drug delivery systems. Here, the polymers are used as emulsifiers, micelles, or polymersomes with a hydrophilic corona block and a hydrophobic core or membrane. The aggregation behavior in aqueous solutions of a series of different amphiphilic block copolypeptoids comprising polysarcosine as a hydrophilic part is here reported. The formation of aggregates is investigated with 1H NMR spectroscopy and dynamic light scattering, and the determination of the critical micelle concentration (cmc) is performed using pyrene fluorescence spectroscopy. For the different block copolypeptoids cmc values ranging from 0.6 × 10-6 M to 0.1 × 10-3 M are found. The tendency to form micelles increases with increasing hydrophobicity at the nitrogen side chain in the hydrophobic moiety. Furthermore, in the case of the same hydrophobic side chain, a decreasing hydrophilic/lipophilic balance leads to the formation of larger aggregates. The aggregates formed in the buffer are able to solubilize the hydrophobic model compounds Reichardt\\'s dye and pyrene, and exhibit versatile microenvironments. Final investigations about the cytotoxicity reveal that the block copolypeptoids are well tolerated by mammalian cells up to high concentrations.

  3. Hydrophobic Effect of Amphiphilic Derivatives of Chitosan on the Antifungal Activity against Aspergillus flavus and Aspergillus parasiticus

    Directory of Open Access Journals (Sweden)

    Vera Ap. de Oliveira Tiera

    2013-04-01

    Full Text Available Low molecular weight amphiphilic derivatives of chitosan were synthesized, characterized and their antifungal activities against Aspergillus flavus and Aspergillus parasiticus were tested. The derivatives were synthesized using as starting material a deacetylated chitosan sample in a two step process: the reaction with propyltrimethyl-ammonium bromide (Pr, followed by reductive amination with dodecyl aldehyde. Aiming to evaluate the effect of the hydrophobic modification of the derivatives on the antifungal activity against the pathogens, the degree of substitution (DS1 by Pr groups was kept constant and the proportion of dodecyl (Dod groups was varied from 7 to 29% (DS2. The derivatives were characterized by 1H-NMR and FTIR and their antifungal activities against the pathogens were tested by the radial growth of the colony and minimum inhibitory concentration (MIC methods. The derivatives substituted with only Pr groups exhibited modest inhibition against A. flavus and A. parasiticus, like that obtained with deacetylated chitosan. Results revealed that the amphiphilic derivatives grafted with Dod groups exhibited increasing inhibition indexes, depending on polymer concentration and hydrophobic content. At 0.6 g/L, all amphiphilic derivatives having from 7.0 to 29% of Dod groups completely inhibited fungal growth and the MIC values were found to decrease from 4.0 g/L for deacetylated chitosan to 0.25–0.50 g/L for the derivatives. These new derivatives open up the possibility of new applications and avenues to develop effective biofungicides based on chitosan.

  4. Adsorption and Aqueous Lubricating Properties of Charged and Neutral Amphiphilic Diblock Copolymers at a Compliant, Hydrophobic Interface

    DEFF Research Database (Denmark)

    Røn, Troels; Javakhishvili, Irakli; Jankova Atanasova, Katja;

    2013-01-01

    We have investigated the adsorption and lubricating properties of neutral and charged amphiphilic diblock copolymers at a hydrophobic polydimethylsiloxane (PDMS) interface in an aqueous environment. The diblock copolymers consist of a hydrophilic block of either neutral poly(ethylene glycol) (PEG......) or negatively charged poly(acrylic acid) (PAA) and of a hydrophobic block of polystyrene (PS) or poly(2-methoxyethyl acrylate) (PMEA), thus generating PEG-b-X or PAA-b-X, where X block is either PS or PMEA. The molecular weight ratios were roughly 1:1 with each block ca. 5 kDa. Comparing the neutral PEG...... and charged PAA buoyant blocks with all other conditions identical, the former showed superior adsorption onto nonpolar, hydrophobic PDMS surfaces from a neutral aqueous solution. PEGbased copolymers showed substantial adsorption for both PS and PMEA as the anchoring block, whereas PAA-based copolymers showed...

  5. Chemoenzymatic Synthesis of Amphiphilic Core-Shell TMP-(PCL-b-PGMA2)3 Star-Block Copolymer.

    Science.gov (United States)

    Wang, Shuwei; Li, Yapeng; Zhang, Xiaonan; Chen, Xuesi; Wang, Jingyuan; Zhang, He-Xin; Yoon, Keun-Byoung

    2015-06-01

    A novel well-defined amphiphilic Core-Shell star-block copolymer was synthesized from trimethylolpropane, ε-caprolactone, and glycidyl methacrylate by a combination of enzymatic ring-opening polymerization and atom transfer radical polymerization. The structure and molecular weight of the macroinitiator and the star-block copolymer were confirmed by means of nuclear magnetic resonance and gel permeation chromatography. The effects of the glycidyl methacrylate sequence length on the hydrodynamic diameter and morphology of the polymer micelles were investigated by dynamic light scattering and transmission electron microscopy, respectively. PMID:26369103

  6. Azimuthal anchoring of a nematic liquid crystal on a grooved interface with anisotropic polar anchoring

    Institute of Scientific and Technical Information of China (English)

    Zhou Xuan; Zhang Zhi-Dong; Ye Wen-Jiang; Xuan Li

    2012-01-01

    Zhang Y Jet al.[Zhang Y J,Zhang Z D,Zhu L Z and Xuan L 2011 Liquid Cryst.38 355] investigated the effects of finite polar anchoring on the azimuthal anchoring energy at a grooved interface,in which polar anchoring was isotropic in the local tangent plane of the surface.In this paper,we investigate the effects of both isotropic and anisotropic polar anchoring on the surface anchoring energy in the frame of Fukuda et al.'s theory.The results show that anisotropic polar anchoring strengthens the azimuthal anchoring of grooved surfaces.In the one-elastic-constant approximation (K11 =K22 =K33 =K),the surface-groove-induced azimuthal anchoring energy is entirely consistent with the result of Faetti,and it reduces to the original result of Berreman with an increase in polar anchoring.Moreover,the contribution of the surface-like elastic term to the Rapini-Papoular anchoring energy is zero.

  7. Salt Effect on the Cloud Point Phenomenon of Amphiphilic Drug-Hydroxypropylmethyl Cellulose System

    Directory of Open Access Journals (Sweden)

    Mohd. Sajid Ali

    2014-01-01

    Full Text Available Effect of two amphiphilic drugs (tricyclic antidepressant, nortriptyline hydrochloride (NORT, and nonsteroidal anti-inflammatory drug, sodium salt of ibuprofen (IBF on the cloud point of biopolymer hydroxypropylmethyl cellulose (HPMC was studied. Effect of NaCl was also seen on the CP of HPMC-drug system. CP of HPMC increases uniformly on increasing the (drug. Both drugs, though one being anionic (IBF and other cationic (NORT, affect the CP in almost the same manner but with different extent implying the role of hydrophobicity in the interaction between drug and polymer. Salt affects the CP of the drug in a dramatic way as low concentration of salt was only able to increase the value of the CP, though not affecting the pattern. However, in presence of high concentration of salts, minimum was observed on CP versus (drug plots. Various thermodynamic parameters were evaluated and discussed on the basis of the observed results.

  8. Effects of X-shaped reduction-sensitive amphiphilic block copolymer on drug delivery

    Directory of Open Access Journals (Sweden)

    Xiao H

    2015-08-01

    Full Text Available Haijun Xiao, Lu WangState Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, People’s Republic of ChinaAbstract: To study the effects of X-shaped amphiphilic block copolymers on delivery of docetaxel (DTX and the reduction-sensitive property on drug release, a novel reduction-sensitive amphiphilic copolymer, (PLGA2-SS-4-arm-PEG2000 with a Gemini-like X-shape, was successfully synthesized. The formation of nanomicelles was proved with respect to the blue shift of the emission fluorescence as well as the fluorescent intensity increase of coumarin 6-loaded particles. The X-shaped polymers exhibited a smaller critical micelle concentration value and possessed higher micellar stability in comparison with those of linear ones. The size of X-shaped (PLGA2-SS-4-arm-PEG2000 polymer nanomicelles (XNMs was much smaller than that of nanomicelles prepared with linear polymers. The reduction sensitivity of polymers was confirmed by the increase of micellar sizes as well as the in vitro drug release profile of DTX-loaded XNMs (DTX/XNMs. Cytotoxicity assays in vitro revealed that the blank XNMs were nontoxic against A2780 cells up to a concentration of 50 µg/mL, displaying good biocompatibility. DTX/XNMs were more toxic against A2780 cells than other formulations in both dose- and time-dependent manners. Cellular uptake assay displayed a higher intracellular drug delivery efficiency of XNMs than that of nanomicelles prepared with linear polymers. Besides, the promotion of tubulin polymerization induced by DTX was visualized by immunofluorescence analysis, and the acceleration of apoptotic process against A2780 cells was also imaged using a fluorescent staining method. Therefore, this X-shaped reduction-sensitive (PLGA2-SS-4-arm-PEG2000 copolymer could effectively improve the micellar stability and significantly enhance the therapeutic efficacy of DTX by increasing the cellular uptake and

  9. Anchored nanostructure materials and method of fabrication

    Science.gov (United States)

    Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

    2012-11-27

    Anchored nanostructure materials and methods for their fabrication are described. The anchored nanostructure materials may utilize nano-catalysts that include powder-based or solid-based support materials. The support material may comprise metal, such as NiAl, ceramic, a cermet, or silicon or other metalloid. Typically, nanoparticles are disposed adjacent a surface of the support material. Nanostructures may be formed as anchored to nanoparticles that are adjacent the surface of the support material by heating the nano-catalysts and then exposing the nano-catalysts to an organic vapor. The nanostructures are typically single wall or multi-wall carbon nanotubes.

  10. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    DEFF Research Database (Denmark)

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C.;

    2016-01-01

    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We the...... of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy...... then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients...... with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any...

  11. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Anne-Marie Ellegaard

    2016-07-01

    Full Text Available Non-small cell lung cancer (NSCLC is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy.

  12. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment.

    Science.gov (United States)

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C; Anand, Atul; Cederkvist, Luise; Petersen, Nikolaj H T; Nylandsted, Jesper; Stenvang, Jan; Mellemgaard, Anders; Østerlind, Kell; Friis, Søren; Jäättelä, Marja

    2016-07-01

    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy. PMID:27333030

  13. Surface damping effect of anchored constrained viscoelastic layers on the flexural response of simply supported structures

    Science.gov (United States)

    Karim, K. R.; Chen, G. D.

    2012-02-01

    Viscoelastic (VE) materials are commonly used to control vibration-induced fatigue in airframes and to suppress general vibration in various structures. This study investigates the effects of anchored constrained VE layers on the flexural response of simply supported Euler beams or plate strips under base excitations. Emphasis is placed on the development of two surface damping treatments: one VE layer anchored at one end, and two VE layers anchored at their different ends. Each anchorage is realized with a thin stiff layer in tension, such as a fiber reinforced polymer sheet, bonded to the surface of a VE layer and anchored to one end of the beam for maximum shear deformation in the constrained VE layer. Non-uniform shear deformation in VE layers is taken into account in the new solution formulation. Sensitivity analyses are performed to understand and quantify the effects of various parameters on flexural responses of the structures. The minimum thickness of VE layers is mainly bounded by the relative stiffness between the VE layers and the constraining face layer. The performances of various configurations are compared and the two-end anchored configuration is found most effective in vibration suppression.

  14. Design of nanostructures based on aromatic peptide amphiphiles.

    Science.gov (United States)

    Fleming, Scott; Ulijn, Rein V

    2014-12-01

    Aromatic peptide amphiphiles are gaining popularity as building blocks for the bottom-up fabrication of nanomaterials, including gels. These materials combine the simplicity of small molecules with the versatility of peptides, with a range of applications proposed in biomedicine, nanotechnology, food science, cosmetics, etc. Despite their simplicity, a wide range of self-assembly behaviours have been described. Due to varying conditions and protocols used, care should be taken when attempting to directly compare results from the literature. In this review, we rationalise the structural features which govern the self-assembly of aromatic peptide amphiphiles by focusing on four segments, (i) the N-terminal aromatic component, (ii) linker segment, (iii) peptide sequence, and (iv) C-terminus. It is clear that the molecular structure of these components significantly influences the self-assembly process and resultant supramolecular architectures. A number of modes of assembly have been proposed, including parallel, antiparallel, and interlocked antiparallel stacking conformations. In addition, the co-assembly arrangements of aromatic peptide amphiphiles are reviewed. Overall, this review elucidates the structural trends and design rules that underpin the field of aromatic peptide amphiphile assembly, paving the way to a more rational design of nanomaterials based on aromatic peptide amphiphiles. PMID:25199102

  15. Synthesis of Bioinspired Carbohydrate Amphiphiles that Promote and Inhibit Biofilms.

    Science.gov (United States)

    Dane, Eric L; Ballok, Alicia E; O'Toole, George A; Grinstaff, Mark W

    2014-02-01

    The synthesis and characterization of a new class of bioinspired carbohydrate amphiphiles that modulate Pseudomonas aeruginosa biofilm formation are reported. The carbohydrate head is an enantiopure poly-amido-saccharide (PAS) prepared by a controlled anionic polymerization of β-lactam monomers derived from either glucose or galactose. The supramolecular assemblies formed by PAS amphiphiles are investigated in solution using fluorescence assays and dynamic light scattering. Dried samples are investigated using X-ray, infrared spectroscopy, and transmission electron microscopy. Additionally, the amphiphiles are evaluated for their ability to modulate biofilm formation by the Gram-negative bacterium Pseudomonas aeruginosa. Remarkably, from a library of eight amphiphiles, we identify a structure that promotes biofilm formation and two structures that inhibit biofilm formation. Using biological assays and electron microscopy, we relate the chemical structure of the amphiphiles to the observed activity. Materials that modulate the formation of biofilms by bacteria are important both as research tools for microbiologists to study the process of biofilm formation and for their potential to provide new drug candidates for treating biofilm-associated infections.

  16. A novel route for fabricating metal-polymer composite nanoparticles with phase-separated structures.

    Science.gov (United States)

    Yabu, Hiroshi; Koike, Kazutaka; Motoyoshi, Kiwamu; Higuchi, Takeshi; Shimomura, Masatsugu

    2010-07-15

    Au nanoparticles (NPs) and polymer composite particles with phase-separation structures were prepared based on phase separation structures. Au NPs were successfully synthesized in amphiphilic block-copolymer micelles, and then composite particles were formed by a simple solvent evaporation process from Au NPs and polymer solution. The phase separated structures (Janus and Core-shell) were controlled by changing the combination of polymers having differing hydrophobicity. PMID:21567522

  17. Anchoring Adjusted Capital Asset Pricing Model

    OpenAIRE

    Hammad, Siddiqi

    2015-01-01

    An anchoring adjusted Capital Asset Pricing Model (ACAPM) is developed in which the payoff volatilities of well-established stocks are used as starting points that are adjusted to form volatility judgments about other stocks. Anchoring heuristic implies that such adjustments are typically insufficient. ACAPM converges to CAPM with correct adjustment, so CAPM is a special case of ACAPM. The model provides a unified explanation for the size, value, and momentum effects in the stock market. A ke...

  18. A New Class of Amphiphiles Bearing Rigid Hydrophobic Groups for Solubilization and Stabilization of Membrane Proteins

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Rasmussen, Søren G F; Rana, Rohini R;

    2012-01-01

    Non-traditional amphiphiles: Conferring aqueous solubility on membrane proteins generally requires the use of a detergent or other amphiphilic agent. A new class of amphiphiles was synthesized, based on steroidal lipophilic groups, and evaluated with several membrane proteins. The results show th...

  19. Improving performance by anchoring movement and "nerves".

    Science.gov (United States)

    Iso-Ahola, Seppo E; Dotson, Charles O; Jagodinsky, Adam E; Clark, Lily C; Smallwood, Lorraine L; Wilburn, Christopher; Weimar, Wendi H; Miller, Matthew W

    2016-10-01

    Golf's governing bodies' recent decision to ban all putting styles "anchoring one end of the club against the body" bridges an important practical problem with psychological theory. We report the first experiment testing whether anchoring provides technical and/or psychological advantage in competitive performance. Many "greats" of professional golf from Arnold Palmer and Jack Nicklaus to Tiger Woods have argued against anchoring, believing that it takes "nerves" out of competitive performance and therefore artificially levels the playing field. To shed more light on the issue, we tested participants' performance with anchored and unanchored putters under low and high pressure when controlling for the putter length. We found no statistically significant evidence for a technical advantage due to anchoring but a clear psychological advantage: participants who anchored their putters significantly outperformed unanchored counterparts under high, but not low, pressure. Results provide tentative evidence for the ban's justification from a competitive standpoint. However, before any definite conclusions can be made, more research is needed when using high-level golfers. PMID:27459587

  20. The Use of Comics-Based Cases in Anchored Instruction

    Science.gov (United States)

    Kneller, Matthew F.

    2009-01-01

    The primary purpose of this research was to understand how comics fulfill the role of anchor in an anchored instruction learning environment. Anchored instruction addresses the inert knowledge problem through the use of realistic multimedia stories, or "anchors," that embed a problem and the necessary data to solve it within the narrative. In the…

  1. Redox-controllable amphiphilic [2]rotaxanes.

    Science.gov (United States)

    Tseng, Hsian-Rong; Vignon, Scott A; Celestre, Paul C; Perkins, Julie; Jeppesen, Jan O; Di Fabio, Alberto; Ballardini, Roberto; Gandolfi, M Teresa; Venturi, Margherita; Balzani, Vincenzo; Stoddart, J Fraser

    2004-01-01

    With the fabrication of molecular electronic devices (MEDs) and the construction of nanoelectromechanical systems (NEMSs) as incentives, two constitutionally isomeric, redox-controllable [2]rotaxanes have been synthesized and characterized in solution. Therein, they both behave as near-perfect molecular switches, that is, to all intents and purposes, these two rotaxanes can be switched precisely by applying appropriate redox stimuli between two distinct chemomechanical states. Their dumbbell-shaped components are composed of polyether chains interrupted along their lengths by i) two pi-electron rich recognition sites-a tetrathiafulvalene (TTF) unit and a 1,5-dioxynaphthalene (DNP) moiety-with ii) a rigid terphenylene spacer placed between the two recognition sites, and then terminated by iii) a hydrophobic tetraarylmethane stopper at one end and a hydrophilic dendritic stopper at the other end of the dumbbells, thus conferring amphiphilicity upon these molecules. A template-directed protocol produces a means to introduce the tetracationic cyclophane, cyclobis(paraquat-p-phenylene) (CBPQT(4+)), which contains two pi-electron accepting bipyridinium units, mechanically interlocked around the dumbbell-shaped components. Both the TTF unit and the DNP moiety are potential stations for CBPQT(4+), since they can establish charge-transfer and hydrogen bonding interactions with the bipyridinium units of the cyclophane, thereby introducing bistability into the [2]rotaxanes. In both constitutional isomers, (1)H NMR and absorption spectroscopies, together with electrochemical investigations, reveal that the CBPQT(4+) ring is predominantly located on the TTF unit, leading to the existence of a single translational isomer (co-conformation) in both cases. In addition, a model [2]rotaxane, incorporating hydrophobic tetraarylmethane stoppers at both ends of its dumbbell-shaped component, has also been synthesized as a point of reference. Molecular synthetic approaches were used to

  2. Magnetic Amphiphilic Composites Applied for the Treatment of Biodiesel Wastewaters

    Directory of Open Access Journals (Sweden)

    Bruno R. S. Lemos

    2012-05-01

    Full Text Available In this work, new magnetic amphiphilic composites were prepared by chemical vapor deposition with ethanol on the surface of hydrophilic natural chrysotile matrix containing Fe catalyst. XRD, Raman, Mössbauer and SEM analyses suggest the formation of a complex nanostructured material composed of hydrophobic carbon nanotubes/nanofibers grown on the hydrophilic surface of the MgSi fiber mineral and the presence of Fe metallic nanoparticles coated by carbon. These nanostructured particles show amphiphilic properties and interact very well with both oil and aqueous phases. When added to emulsions the amphiphilic particles locate on the oil/water interface and, under a magnetic field, the oil droplets collapsed leading to the separation of the aqueous and oil phases. Preliminary work showed excellent results on the use of these particles to break wastewater emulsions in the biodiesel process.

  3. Competitive Binding of Natural Amphiphiles with Graphene Derivatives

    Science.gov (United States)

    Radic, Slaven; Geitner, Nicholas K.; Podila, Ramakrishna; Käkinen, Aleksandr; Chen, Pengyu; Ke, Pu Chun; Ding, Feng

    2013-07-01

    Understanding the transformation of graphene derivatives by natural amphiphiles is essential for elucidating the biological and environmental implications of this emerging class of engineered nanomaterials. Using rapid discrete-molecular-dynamics simulations, we examined the binding of graphene and graphene oxide with peptides, fatty acids, and cellulose, and complemented our simulations by experimental studies of Raman spectroscopy, FTIR, and UV-Vis spectrophotometry. Specifically, we established a connection between the differential binding and the conformational flexibility, molecular geometry, and hydrocarbon content of the amphiphiles. Importantly, our dynamics simulations revealed a Vroman-like competitive binding of the amphiphiles for the graphene oxide substrate. This study provides a mechanistic basis for addressing the transformation, evolution, transport, biocompatibility, and toxicity of graphene derivatives in living systems and the natural environment.

  4. Synthesis of silver nanoparticles in melts of amphiphilic polyesters

    International Nuclear Information System (INIS)

    The current work presents a one-step procedure for the synthesis of amphiphilic silver nanoparticles suitable for production of silver-filled polymeric materials. This solvent free synthesis via reduction of Tollens’ reagent as silver precursor in melts of amphiphilic polyesters consisting of hydrophilic poly(ethylene glycol) blocks and hydrophobic alkyl chains allows the production of silver nanoparticles without any by-product formation. This makes them especially interesting for the production of medical devices with antimicrobial properties. In this article the influences of the chain length of the hydrophobic block in the amphiphilic polyesters and the process temperature on the particle size distribution (PSD) and the stability of the particles against agglomeration are discussed. According to the results of spectroscopic and viscosimetric investigations the silver precursor is reduced to elemental silver nanoparticles by a single electron transfer process from the poly(ethylene glycol) chain to the silver ion. (paper)

  5. Synthesis and characterization of polymer layers for control of fluid transport

    Science.gov (United States)

    Vatansever, Fehime

    The level of wetting of fiber surface with liquids is an important characteristic of fibrous materials. It is related to fiber surface energy and the structure of the material. Surface energy can be changed by surface modification via the grafting methodologies that have been reported for introducing new and stable functionality to fibrous substrates without changing bulk properties. Present work is dedicated to synthesis and characterization of macromolecular layers grafted to fiber surface in order to achieve directional liquid transport for the modified fabric. Modification technique used here is based on formation of stable polymer layer on fabric surface using "grafting to" technique. Specifically, modification of fabric with wettability gradient for facilitated one way-liquid transport, and pointed modification of yarn-based channels on textile microfluidic device for directional liquid transport are reported here. First, fabric was activated with alkali (NaOH) solution. Second, poly (glycidyl methacrylate) (PGMA) was deposited on fabric as an anchoring layer. Finally, polymers of interest were grafted to surface through the epoxy functionality of PGMA. Effect of polymer grafting on the wicking property of the fabric has been evaluated by vertical wicking technique at the each step of surface modification. The results shows that wicking performance of fabric can be altered by grafting of a thin nanoscale polymeric film. For the facilitated liquid transport, the gradient polymer coating was created using "grafting to" technique and its dependence on the grafting temperature. Wettability gradient from hydrophilic to hydrophobic (change in water contact angle from 0 to 140 degrees on fabric) was achieved by grafting of polystyrene (PS) and polyacrylic acid (PAA) sequentially with concentration gradient. This study proposes that fabric with wettability gradient property can be used to transfer sweat from skin and support moisture management when it is used in a

  6. Photosensitizer enhanced disassembly of amphiphilic micelle for ROS-response targeted tumor therapy in vivo.

    Science.gov (United States)

    Dai, Liangliang; Yu, Yonglin; Luo, Zhong; Li, Menghuan; Chen, Weizhen; Shen, Xinkun; Chen, Feng; Sun, Qiang; Zhang, Qingfeng; Gu, Hao; Cai, Kaiyong

    2016-10-01

    This study reports a reactive oxygen species (ROS) sensitive drug delivery system based on amphiphilic polymer of poly(propylene sulfide)-polyethylene glycol-serine-folic acid (PPS-mPEG-Ser-FA). The polymer could form homogeneous micelles with an average diameter of around 80 nm through self-assembly, which would then be loaded with the singlet oxygen-generating photosensitizer of zinc phthalocyanine (ZNPC) and anti-cancer drug of DOX. The disassembly of micelles could be triggered by the hydrophobic to hydrophilic transition of the PPS core in response to ROS-induced oxidation in vitro. ZNPC molecules are capable of producing ROS under laser irradiation, which results in the rapid disassembly of micelles and releasing of the anti-tumor drug for tumor therapy under physiological condition otherwise. Moreover, the excessive ROS production deriving from ZNPC synergically induces cells apoptosis. Furthermore, the DOX loaded amphiphilic micelles could be internalized by tumor cells via FA receptor-mediated endocytosis to effectively inhibit the tumor growth in vivo, while with only minimal toxic side effects. The results in vitro and in vivo consistently demonstrate that the light-responsive micelle is a promising biodegradable nanocarrier for on-command drug release and targeted tumor therapy. PMID:27423095

  7. Synthesis and Characterization of Biodegradable Amphiphilic Star and Y-Shaped Block Copolymers as Potential Carriers for Vinorelbine

    Directory of Open Access Journals (Sweden)

    Fatemeh Bahadori

    2014-01-01

    Full Text Available Two amphiphilic block copolymers using hydrophobic poly(ε-caprolactone (PCL and hydrophilic poly(ethylene glycol (PEG were successfully synthesized. One of them is an (A-b-B4 type star polymer [(PCL-b-PEG4] and the other one is a Y-shaped PEG–(PCL2. A star-shaped polymer (PCL-b-PEG4 was prepared by ring-opening polymerization (ROP of ε-caprolactone continued by click reaction of (PCL-azide4 and PEG-alkyne. The synthesis of Y-shaped PEG–(PCL2 block copolymer was carried out via Diels-Alder click reaction of a furan protected maleimide end-functionalized PEG (PEG-MI with an anthracene end-functionalized PCL following the ROP of ε-caprolactone. The characterization of micelles is carried out using both materials in aqueous media as drug delivery vehicles, which showed satisfying results and enhanced the cytotoxic effect of the anti-cancer drug vinorelbine (VLB. However, micelles consisted of Y-shaped unimers were found to be more convenient for delivery of hydrophobic drugs such as VLB because they formed in lower concentration, carrying a higher amount of drugs and owing a monomodal distribution. We concluded that the free tails of hydrophobic chains in Y-shaped block copolymer facilitate the assembly of amphiphilic material in water to form micelles.

  8. Anchors as Semantic Primes in Value Construction: An EEG Study of the Anchoring Effect.

    Directory of Open Access Journals (Sweden)

    Qingguo Ma

    Full Text Available Previous research regarding anchoring effects has demonstrated that human judgments are often assimilated to irrelevant information. Studies have demonstrated that anchors influence the economic valuation of various products and experiences; however, the cognitive explanations of this effect remain controversial, and its neural mechanisms have rarely been explored. In the current study, we conducted an electroencephalography (EEG experiment to investigate the anchoring effect on willingness to accept (WTA for an aversive hedonic experience and the role of anchors in this judgment heuristic. The behavioral results demonstrated that random numbers affect participants' WTA for listening to pieces of noise. The participants asked for higher pay after comparing their WTA with higher numbers. The EEG results indicated that anchors also influenced the neural underpinnings of the valuation process. Specifically, when a higher anchor number was drawn, larger P2 and late positive potential amplitudes were elicited, reflecting the anticipation of more intensive pain from the subsequent noise. Moreover, higher anchors induced a stronger theta band power increase compared with lower anchors when subjects listened to the noises, indicating that the participants felt more unpleasant during the actual experience of the noise. The levels of unpleasantness during both anticipation and experience were consistent with the semantic information implied by the anchors. Therefore, these data suggest that a semantic priming process underlies the anchoring effect in WTA. This study provides proof for the robustness of the anchoring effect and neural evidence of the semantic priming model. Our findings indicate that activated contextual information, even seemingly irrelevant, can be embedded in the construction of economic value in the brain.

  9. Anchors as Semantic Primes in Value Construction: An EEG Study of the Anchoring Effect.

    Science.gov (United States)

    Ma, Qingguo; Li, Diandian; Shen, Qiang; Qiu, Wenwei

    2015-01-01

    Previous research regarding anchoring effects has demonstrated that human judgments are often assimilated to irrelevant information. Studies have demonstrated that anchors influence the economic valuation of various products and experiences; however, the cognitive explanations of this effect remain controversial, and its neural mechanisms have rarely been explored. In the current study, we conducted an electroencephalography (EEG) experiment to investigate the anchoring effect on willingness to accept (WTA) for an aversive hedonic experience and the role of anchors in this judgment heuristic. The behavioral results demonstrated that random numbers affect participants' WTA for listening to pieces of noise. The participants asked for higher pay after comparing their WTA with higher numbers. The EEG results indicated that anchors also influenced the neural underpinnings of the valuation process. Specifically, when a higher anchor number was drawn, larger P2 and late positive potential amplitudes were elicited, reflecting the anticipation of more intensive pain from the subsequent noise. Moreover, higher anchors induced a stronger theta band power increase compared with lower anchors when subjects listened to the noises, indicating that the participants felt more unpleasant during the actual experience of the noise. The levels of unpleasantness during both anticipation and experience were consistent with the semantic information implied by the anchors. Therefore, these data suggest that a semantic priming process underlies the anchoring effect in WTA. This study provides proof for the robustness of the anchoring effect and neural evidence of the semantic priming model. Our findings indicate that activated contextual information, even seemingly irrelevant, can be embedded in the construction of economic value in the brain.

  10. Methotrexate-Loaded Four-Arm Star Amphiphilic Block Copolymer Elicits CD8+ T Cell Response against a Highly Aggressive and Metastatic Experimental Lymphoma.

    Science.gov (United States)

    Hira, Sumit Kumar; Ramesh, Kalyan; Gupta, Uttam; Mitra, Kheyanath; Misra, Nira; Ray, Biswajit; Manna, Partha Pratim

    2015-09-16

    We have synthesized a well-defined four-arm star amphiphilic block copolymer [poly(DLLA)-b-poly(NVP)]4 [star-(PDLLA-b-PNVP)4] that consists of D,L-lactide (DLLA) and N-vinylpyrrolidone (NVP) via the combination of ring-opening polymerization (ROP) and xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. Synthesis of the polymer was verified by 1H NMR spectroscopy and gel permeation chromatography (GPC). The amphiphilic four-arm star block copolymer forms spherical micelles in water as demonstrated by transmission electron microscopy (TEM) and 1H NMR spectroscopy. Pyrene acts as a probe to ascertain the critical micellar concentration (cmc) by using fluorescence spectroscopy. Methotrexate (MTX)-loaded polymeric micelles of star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer were prepared and characterized by fluorescence and TEM studies. Star-(PDLLA15-b-PNVP10)4 copolymer was found to be significantly effective with respect to inhibition of proliferation and lysis of human and murine lymphoma cells. The amphiphilic block copolymer causes cell death in parental and MTX-resistant Dalton lymphoma (DL) and Raji cells. The formulation does not cause hemolysis in red blood cells and is tolerant to lymphocytes compared to free MTX. Therapy with MTX-loaded star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer micelles prolongs the life span of animals with neoplasia by reducing the tumor load, preventing metastasis and augmenting CD8+ T cell-mediated adaptive immune responses. PMID:26323031

  11. Cationic Antimicrobial Polymers and Their Assemblies

    Directory of Open Access Journals (Sweden)

    Ana Maria Carmona-Ribeiro

    2013-05-01

    Full Text Available Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs. The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications.

  12. Monitoring ground anchor using non-destructive ground anchor integrity test (NDT-GRANIT)

    Energy Technology Data Exchange (ETDEWEB)

    Robbany, Z., E-mail: zdrobbany@gmail.com; Handayani, G., E-mail: gunawanhandayani@gmail.com [Earth Physics and Complex System Laboratory, Department of Physics, Institut Teknologi Bandung, Ganesha 10 Bandung, Indonesia 40132 (Indonesia)

    2015-09-30

    Monitoring at ground anchor commonly uses a pull out test method, therefor we developing a non-destructive ground anchor integrity testing (NDT-GRANIT). NDT-GRANIT using the principle of seismic waves that have been modified into form of sweep signal, the signal will be demodulated, filtered, and Fourier transformation (inverse discrete Fourier transform) so the data can be interpreted reflected wave from the ground anchor. The method was applied to determine whether the ground anchor still gripped in the subsurface by looking the attenuation of the wave generated sources. From the result we can see that ground anchor does not grip. To validate the results of the comparison method of measurement used pile integrity test.

  13. Polymer dynamics in nanoconfinement: Interfaces and interphases

    Directory of Open Access Journals (Sweden)

    Krutyeva Margarita

    2015-01-01

    Full Text Available The dynamics of polymers in nanoconfinement was studied by using neutron spectroscopy. A number of pronounced effects on different time and length scales for the polymers confined in nanopores of anodic aluminium oxide were observed. Local segmental dynamics was found to be dependent on the type of the interaction between the solid pore wall and polymer: attractive interactions lead to the formation of a surface layer with the dynamics slowed down as compared to the dynamics of pure polymer; neutral/repulsive interaction do not change the local dynamics. Attractive interactions cause anchoring of polymer segments on the surface creating an interphase between the polymer in close vicinity to the solid surface and pure polymer. In addition, at strong confinement conditions the dilution of the entanglement network is observed.

  14. Spin-Casting Polymer Brush Films for Stimuli-Responsive and Anti-Fouling Surfaces.

    Science.gov (United States)

    Xu, Binbin; Feng, Chun; Hu, Jianhua; Shi, Ping; Gu, Guangxin; Wang, Lei; Huang, Xiaoyu

    2016-03-01

    Surfaces modified with amphiphilic polymers can dynamically alter their physicochemical properties in response to changes of their environmental conditions; meanwhile, amphiphilic polymer coatings with molecular hydrophilic and hydrophobic patches, which can mitigate biofouling effectively, are being actively explored as advanced coatings for antifouling materials. Herein, a series of well-defined amphiphilic asymmetric polymer brushes containing hetero side chains, hydrophobic polystyrene (PS) and hydrophilic poly(ethylene glycol) (PEG), was employed to prepare uniform thin films by spin-casting. The properties of these films were investigated by water contact angle, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and quartz crystal microbalance (QCM). AFM showed smooth surfaces for all films with the roughness less than 2 nm. The changes in water contact angle and C/O ratio (XPS) evidenced the enrichment of PEG or PS chains at film surface after exposed to selective solvents, indicative of stimuli- responsiveness. The adsorption of proteins on PEG functionalized surface was quantified by QCM and the results verified that amphiphilic polymer brush films bearing PEG chains could lower or eliminate protein-material interactions and resist to protein adsorption. Cell adhesion experiments were performed by using HaCaT cells and it was found that polymer brush films possess good antifouling ability. PMID:26905980

  15. Langmuir monolayer formation of metal complexes from polymerizable amphiphilic ligands

    NARCIS (Netherlands)

    Werkman, PJ; Schouten, AJ

    1996-01-01

    The monolayer behaviour of 4-(10,12-pentacosadiynoicamidomethyl)-pyridine at the air-water interface was studied by measuring the surface pressure-area isotherms. The amphiphile formed stable monolayers with a clear liquid-expanded (LE) to liquid-condensed phase transition at various temperatures. U

  16. Effects of perfluorinated amphiphiles on backward swimming in Paramecium caudatum

    International Nuclear Information System (INIS)

    PFOS and PFOA are ubiquitous contaminants in the environment. We investigated the effects of fluorochemicals on calcium currents in Paramecium caudatum using its behavioral changes. Negatively charged amphiphiles prolonged backward swimming (BWS) of Paramecium. PFOS significantly prolonged BWS, while PFOA was less potent (EC5: 29.8 ± 4.1 and 424.1 ± 124.0 μM, respectively). The BWS prolongation was blocked by cadmium, indicating that the cellular calcium conductance had been modified. The positively charged amphiphile FOSAPrTMA shortened BWS (EC5: 19.1 ± 17.3). Nonionic amphiphiles did not affect BWS. The longer-chain perfluorinated carboxylates PFNA and PFDA were more potent than PFOA (EC5: 98.7 ± 20.1 and 60.4 ± 10.1 μM, respectively). However, 1,8-perfluorooctanedioic acid and 1,10-perfluorodecanedioic acid did not prolong BWS. The critical micelle concentration (CMC) and BWS prolongation for negatively charged amphiphiles showed a clear correlation (r 2 = 0.8008, p < 0.001). In summary, several perfluorochemicals and PFOS and PFOA had similar effects in Paramecium, while chain length, CMC, and electric charge were major determinants of BWS duration

  17. Bio-based amphiphilic materials development and applications

    Science.gov (United States)

    Farm-based raw materials are increasingly used in the development of amphiphilic materials that have potential applications in the production of a variety of consumer and industrial products, including lubricants. Raw materials of interest include: starches, proteins, fats, oils, and sugars. These ...

  18. Amphiphiles containing aromatic groups in the hydrophobic part

    NARCIS (Netherlands)

    Visscher, Inge

    2004-01-01

    Aggregation processes are essential for life on this planet. For example, the membranes of all living cells are bilayered aggregates, consisting of lipid molecules, proteins and steroids. In many biological processes, aggregates play a role. The main driving force for aggregation of amphiphiles is h

  19. Microphase separation of diblock copolymers with amphiphilic segment

    NARCIS (Netherlands)

    Kriksin, Yury A.; Khalatur, Pavel G.; Erukhimovich, Igor Ya.; ten Brinke, Gerrit; Khokhlov, Alexei R.

    2009-01-01

    We present a statistical mechanical approach for predicting the self-assembled morphologies of amphiphilic diblock copolymers in the melt. We introduce two conformationally asymmetric linear copolymer models with a local structural asymmetry, one of a "comb-tail'' type and another that we call "cont

  20. Self-assembly of fibronectin mimetic peptide-amphiphile nanofibers

    Science.gov (United States)

    Rexeisen, Emilie Lynn

    Many therapeutic strategies incorporate peptides into their designs to mimic the natural protein ligands found in vivo. A few examples are the short peptide sequences RGD and PHSRN that mimic the primary and synergy-binding domains of the extracellular matrix protein, fibronectin, which is recognized by the cell surface receptor, alpha5beta 1 integrin. Even though scaffold modification with biomimetic peptides remains one of the most promising approaches for tissue engineering, the use of these peptides in therapeutic tissue-engineered products and drug delivery systems available on the commercial market is limited because the peptides are not easily able to mimic the natural protein. The design of a peptide that can effectively target the alpha5beta1 integrin would greatly increase biomimetic scaffold therapeutic potential. A novel peptide containing both the RGD primary binding domain and PHSRN synergy-binding domain for fibronectin joined with the appropriate linker should bind alpha 5beta1 integrin more efficiently and lead to greater cell adhesion over RGD alone. Several fibronectin mimetic peptides were designed and coupled to dialkyl hydrocarbon tails to make peptide-amphiphiles. The peptides contained different linkers connecting the two binding domains and different spacers separating the hydrophobic tails from the hydrophilic headgroups. The peptide-amphiphiles were deposited on mica substrates using the Langmuir-Blodgett technique. Langmuir isotherms indicated that the peptide-amphiphiles that contained higher numbers of serine residues formed a more tightly packed monolayer, but the increased number of serines also made transferring the amphiphiles to the mica substrate more difficult. Atomic force microscopy (AFM) images of the bilayers showed that the headgroups might be bent, forming small divots in the surface. These divots may help expose the PHSRN synergy-binding domain. Parallel studies undertaken by fellow group members showed that human

  1. Biomedical applications of glycosylphosphatidylinositol-anchored proteins

    Science.gov (United States)

    Heider, Susanne; Dangerfield, John A.

    2016-01-01

    Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) use a unique posttranslational modification to link proteins to lipid bilayer membranes. The anchoring structure consists of both a lipid and carbohydrate portion and is highly conserved in eukaryotic organisms regarding its basic characteristics, yet highly variable in its molecular details. The strong membrane targeting property has made the anchors an interesting tool for biotechnological modification of lipid membrane-covered entities from cells through extracellular vesicles to enveloped virus particles. In this review, we will take a closer look at the mechanisms and fields of application for GPI-APs in lipid bilayer membrane engineering and discuss their advantages and disadvantages for biomedicine. PMID:27542385

  2. Fibre-Reinforced Adhesive for Structure Anchoring

    Science.gov (United States)

    Barnat, J.; Bajer, M.

    2015-11-01

    The topic of this paper is the glue-concrete interface of bonded anchors loaded by tension force. The paper is closely focused on bond strength experiments using high strength concrete up to class C50/60 or higher together with pure epoxy resin and fibre-reinforced resin. The goal of this research is to find the limits of the effective use of such glue types in high performance concrete, and also to verify the most commonly used design methods for bonded anchors. The presented research includes experimental analysis of the glue-concrete interface and the influence of its parameters on anchor behaviour. The presented analysis shows some problems of the 'separated failure modes' approach and also presents experimentally verified bond strength values obtained for the currently most widespread glue types. Results of fibre reinforced epoxy resin are also presented in this paper.

  3. Polymer films

    Science.gov (United States)

    Granick, Steve; Sukhishvili, Svetlana A.

    2008-12-30

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  4. Self-Assembly of Amphiphilic Block Copolypeptoids – Micelles, Worms and Polymersomes

    Science.gov (United States)

    Fetsch, Corinna; Gaitzsch, Jens; Messager, Lea; Battaglia, Giuseppe; Luxenhofer, Robert

    2016-01-01

    Polypeptoids are an old but recently rediscovered polymer class with interesting synthetic, physico-chemical and biological characteristics. Here, we introduce new aromatic monomers, N-benzyl glycine N-carboxyanhydride and N-phenethyl glycine N-carboxyanhydride and their block copolymers with the hydrophilic polysarcosine. We compare their self-assembly in water and aqueous buffer with the self-assembly of amphiphilic block copolypeptoids with aliphatic side chains. The aggregates in water were investigated by dynamic light scattering and electron microscopy. We found a variety of morphologies, which were influenced by the polymer structure as well as by the preparation method. Overall, we found polymersomes, worm-like micelles and oligo-lamellar morphologies as well as some less defined aggregates of interconnected worms and vesicles. Such, this contribution may serve as a starting point for a more detailed investigation of the self-assembly behavior of the rich class of polypeptoids and for a better understanding between the differences in the aggregation behavior of non-uniform polypeptoids and uniform peptoids. PMID:27666081

  5. Synthesis and characterization of an elastin-mimetic amphiphilic block copolymer protein

    Science.gov (United States)

    Lee, Terrence Anita-Talley

    2000-10-01

    The overall goal in material science is to be able to control the molecular architecture of a material and thus its end properties. There is no method that offers greater control than the biological synthesis of proteins. From the DNA sequence to the final synthesized protein, the entire process is finitely controlled. This present work describes methods developed and used to synthesize protein polymers by manipulating this process. From the initial DNA sequence chosen, the end properties that the protein polymer will have are dictated. An amphiphilic diblock copolymer was designed based on environmentally responsive elastin-mimetic peptide sequences [(Val/Ile)-Pro-Gly-Xaa-Gly] (Xaa = Ala or Glu for the hydrophilic block, Val or Phe for the hydrophobic block) and synthesized using a genetic engineering approach. Differential scanning calorimetry measurements in aqueous solution revealed that reversible hydrophobic folding and assembly of the copolymer occurs above the inverse temperature transition, Tt, of the hydrophobic block. This process results in the formation of 50 nm protein-based micellar aggregates, which were characterized by electron microscopy and temperature-dependent dynamic light scattering techniques. The distribution of micellar aggregates can be altered reproducibly through variation of environmental conditions including pH and temperature. The uniform and defined macromolecular architecture of this protein copolymer permits greater control over the physical properties of the micelles, which therefore may facilitate applications in controlled release of small molecules.

  6. ANCHORING EFFECT ANALYSIS OF TENSIONED BOLTS

    Institute of Scientific and Technical Information of China (English)

    夏建中

    1997-01-01

    The paper analyses quantitatively the anchoring effect of tensioned bolts on surrounding rock strength, and defines two concepts: one is the surrounding rock strength increased amount △τ13 and the other is the strength influence factor k. The anchoring effect of tensioned bolts is considered to increase a strength increased amount △τ13 where △τ13 is the product k and tensioned load p, i. e. △τ13= kp, where k is a function of two variables x and y. The distributive properties both △τ13 and k are also discussed in the paper, obtaining some useful results for designing bolting support parameters.

  7. Starting point anchoring effects in choice experiments

    DEFF Research Database (Denmark)

    Ladenburg, Jacob; Olsen, Søren Bøye

    Anchoring is acknowledged as a potential source of considerable bias in Dichotomous Choice Contingent Valuation studies. Recently, another stated preference method known as Choice Experiments has gained in popularity as well as the number of applied studies. However, as the elicitation of prefere......Anchoring is acknowledged as a potential source of considerable bias in Dichotomous Choice Contingent Valuation studies. Recently, another stated preference method known as Choice Experiments has gained in popularity as well as the number of applied studies. However, as the elicitation...

  8. Substrate-anchored and degradation-sensitive anti-inflammatory coatings for implant materials

    Science.gov (United States)

    Wu, Duo; Chen, Xingyu; Chen, Tianchan; Ding, Chunmei; Wu, Wei; Li, Jianshu

    2015-06-01

    Implant materials need to be highly biocompatible to avoid inflammation in clinical practice. Although biodegradable polymeric implants can eliminate the need for a second surgical intervention to remove the implant materials, they may produce acidic degradation products in vivo and cause non-bacterial inflammation. Here we show the strategy of “substrate-anchored and degradation-sensitive coatings” for biodegradable implants. Using poly(lactic acid)/hydroxyapatite as an implant material model, we constructed a layer-by-layer coating using pH-sensitive star polymers and dendrimers loaded with an anti-inflammatory drug, which was immobilised through a hydroxyapatite-anchored layer. The multifunctional coating can effectively suppress the local inflammation caused by the degradation of implant materials for at least 8 weeks in vivo. Moreover, the substrate-anchored coating is able to modulate the degradation of the substrate in a more homogeneous manner. The “substrate-anchored and degradation-sensitive coating” strategy therefore exhibits potential for the design of various self-anti-inflammatory biodegradable implant materials.

  9. Monogenean anchor morphometry: systematic value, phylogenetic signal, and evolution.

    Science.gov (United States)

    Khang, Tsung Fei; Soo, Oi Yoon Michelle; Tan, Wooi Boon; Lim, Lee Hong Susan

    2016-01-01

    Background. Anchors are one of the important attachment appendages for monogenean parasites. Common descent and evolutionary processes have left their mark on anchor morphometry, in the form of patterns of shape and size variation useful for systematic and evolutionary studies. When combined with morphological and molecular data, analysis of anchor morphometry can potentially answer a wide range of biological questions. Materials and Methods. We used data from anchor morphometry, body size and morphology of 13 Ligophorus (Monogenea: Ancyrocephalidae) species infecting two marine mugilid (Teleostei: Mugilidae) fish hosts: Moolgarda buchanani (Bleeker) and Liza subviridis (Valenciennes) from Malaysia. Anchor shape and size data (n = 530) were generated using methods of geometric morphometrics. We used 28S rRNA, 18S rRNA, and ITS1 sequence data to infer a maximum likelihood phylogeny. We discriminated species using principal component and cluster analysis of shape data. Adams's K mult was used to detect phylogenetic signal in anchor shape. Phylogeny-correlated size and shape changes were investigated using continuous character mapping and directional statistics, respectively. We assessed morphological constraints in anchor morphometry using phylogenetic regression of anchor shape against body size and anchor size. Anchor morphological integration was studied using partial least squares method. The association between copulatory organ morphology and anchor shape and size in phylomorphospace was used to test the Rohde-Hobbs hypothesis. We created monogeneaGM, a new R package that integrates analyses of monogenean anchor geometric morphometric data with morphological and phylogenetic data. Results. We discriminated 12 of the 13 Ligophorus species using anchor shape data. Significant phylogenetic signal was detected in anchor shape. Thus, we discovered new morphological characters based on anchor shaft shape, the length between the inner root point and the outer root

  10. The "Anchor" Method: Principle and Practice.

    Science.gov (United States)

    Selgin, Paul

    This report discusses the "anchor" language learning method that is based upon derivation rather than construction, using Italian as an example of a language to be learned. This method borrows from the natural process of language learning as it asks the student to remember whole expressions that serve as vehicles for learning both words and rules,…

  11. International Lunar Network (ILN) Anchor Nodes

    Science.gov (United States)

    Cohen, Barbara A.

    2009-01-01

    This slide presentation reviews the United States' contribution to the International Lunar Network (ILN) project, the Anchor Nodes project. The ILN is an initiative of 9 national space agencies to establish a set of robotic geophysical monitoring stations on the surface of the Moon. The project is aimed at furthering the understanding of the lunar composition, and interior structure.

  12. Anchor Stress Checking of Security Injection Tank

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The intention of the calculating is to check the anchor stresses of the security injection tank to know whether the stress is satisfied the code requirements on the basis of all the reaction forces gained in the static, seismic and thermal stress results.

  13. The bone-anchored hearing aid

    DEFF Research Database (Denmark)

    Foghsgaard, Søren

    2014-01-01

    The bone-anchored hearing aid (Baha) was introduced in 1977 by Tjellström and colleagues and has now been used clinically for over 30 years. Generally, the outcomes are good, and several studies have shown improved audiological- and quality of life outcomes. The principle of the Baha is, that sound...

  14. Finding Chemical Anchors in the Kitchen

    Science.gov (United States)

    Haim, Liliana

    2005-01-01

    ''The Chemistry Kitchen'', a unit composed of five activities with kitchen elements for elementary students ages 9-11, introduces the children to the skills and chemical working ideas to be used later as anchors for chemical concepts. These activities include kitchen elements, determining the relative mass and so on.

  15. Predicting Anchor Links between Heterogeneous Social Networks

    CERN Document Server

    Sajadmanesh, Sina; Khodadadi, Ali

    2016-01-01

    People usually get involved in multiple social networks to enjoy new services or to fulfill their needs. Many new social networks try to attract users of other existing networks to increase the number of their users. Once a user (called source user) of a social network (called source network) joins a new social network (called target network), a new inter-network link (called anchor link) is formed between the source and target networks. In this paper, we concentrated on predicting the formation of such anchor links between heterogeneous social networks. Unlike conventional link prediction problems in which the formation of a link between two existing users within a single network is predicted, in anchor link prediction, the target user is missing and will be added to the target network once the anchor link is created. To solve this problem, we use meta-paths as a powerful tool for utilizing heterogeneous information in both the source and target networks. To this end, we propose an effective general meta-pat...

  16. Anchoring the Panic Disorder Severity Scale

    Science.gov (United States)

    Keough, Meghan E.; Porter, Eliora; Kredlow, M. Alexandra; Worthington, John J.; Hoge, Elizabeth A.; Pollack, Mark H.; Shear, M. Katherine; Simon, Naomi M.

    2012-01-01

    The Panic Disorder Severity Scale (PDSS) is a clinician-administered measure of panic disorder symptom severity widely used in clinical research. This investigation sought to provide clinically meaningful anchor points for the PDSS both in terms of clinical severity as measured by the Clinical Global Impression-Severity Scale (CGI-S) and to extend…

  17. Periodically Grafted Amphiphilic Copolymers: Effects of Steric Crowding and Reversal of Amphiphilicity.

    Science.gov (United States)

    Mandal, Joydeb; Ramakrishnan, S

    2015-06-01

    Two series of periodically clickable polyesters were prepared; one of them carries alkylene segments along its backbone, whereas the other carries poly(ethylene glycol) (PEG) segments. These polyesters were clicked with either MPEG-350 azide or docosyl (C22) azide to yield periodically grafted amphiphilic copolymers (PGACs) carrying either flexible hydrophilic or crystallizable hydrophobic backbone segments. The immiscibility between hydrocarbon and PEG segments causes both of these systems to fold in either a zigzag or hairpin-like conformation; the hairpin-like conformation appears to be preferred when flexible PEG segments are present in the backbone. The folded chains further reorganize in the solid state to develop a lamellar morphology that permits the collocation of the PEG and hydrocarbon (HC) segments within alternate domains; evidence for the self-segregation was gained from DSC, SAXS, and AFM studies. SAXS studies revealed the formation of an extended lamellar structure, whereas AFM images showed uniform layered morphology with layer heights that matched reasonably well with the interlamellar spacing obtained from the SAXS study. Labeling one representative PGAC, carrying crystallizable long alkylene segments in the backbone and pendant PEG-350 side chains, with a small mole fraction of pyrene fluorophore permitted the examination of the conformational transition that occurs upon going from a good to a poor solvent; this single-chain folded conformation, we postulate, is the intermediate that organizes into the lamellar morphology.

  18. Stone anchors from the Okhamandal region, Gujarat Coast, India

    Digital Repository Service at National Institute of Oceanography (India)

    Sundaresh; Gaur, A.S.; Gudigar, P.; Tripati, S.; Vora, K.H.; Bandodkar, S.N.

    During marine archaeological explorations since 1983, off Dwarka, a large number of stone anchors were discovered and dated to 1400 BC, comparing with anchors found in Mediterranean waters. In recent archaeological explorations off Dwarka, Bet...

  19. Susceptibility to anchoring effects: How openness-to-experience influences responses to anchoring cues

    OpenAIRE

    Todd McElroy; Keith Dowd

    2007-01-01

    Previous research on anchoring has shown this heuristic to be a very robust psychological phenomenon ubiquitous across many domains of human judgment and decision-making. Despite the prevalence of anchoring effects, researchers have only recently begun to investigate the underlying factors responsible for how and in what ways a person is susceptible to them. This paper examines how one such factor, the Big-Five personality trait of openness-to-experience, influences the effect of previously p...

  20. Anchoring energy enhancement and pretilt angle control of liquid crystal alignment on polymerized surfaces

    Directory of Open Access Journals (Sweden)

    Libo Weng

    2015-09-01

    Full Text Available We demonstrate enhanced surface anchoring energy and control of pretilt angle in a nematic liquid crystal cell with vertical alignment and polymerized surfaces (PS-VA. The polymerized surfaces are formed by ultraviolet (UV irradiation-induced phase separation of a minute amount of a reactive monomer in the vertical-aligned nematic liquid crystal. By introducing a bias voltage during UV curing, surface-localized polymer protrusions with a dimension of 100nm and a field-induced pretilt angle are observed. Experimental evidences and theoretical analyses validate that PS-VA has increased surface anchoring strength by two folds and pretilt angle has been changed from 89° to 86° compared to those of a VA cell. The enabling PS-VA cell technique with excel electro-optical properties such as very good dark state, high optical contrast, and fast rise and decay times may lead to development of a wide range of applications.

  1. Career Paths, Images and Anchors: A Study with Brazilian Professionals

    Science.gov (United States)

    Kilimnik, Zelia Miranda; de Oliveira, Luiz Claudio Vieira; Sant'anna, Anderson De Souza; Barros, Delba Teixeira Rodrigues

    2011-01-01

    This article analyses career anchors changes associated to images and professionals trajectories. Its main question: Do anchors careers change through time? We conducted twelve interviews involving professionals from the Administration Area, applying Schein's Career Anchors Inventory (1993). We did the same two years later. In both of them, the…

  2. Students' Anchoring Predisposition: An Illustration from Spring Training Baseball

    Science.gov (United States)

    Mohrweis, Lawrence C.

    2014-01-01

    The anchoring tendency results when decision makers anchor on initial values and then make final assessments that are adjusted insufficiently away from the initial values. The professional literature recognizes that auditors often risk falling into the judgment trap of anchoring and adjusting (Ranzilla et al., 2011). Students may also be unaware…

  3. Synthesis, characterization and comparative evaluation of phenoxy ring containing long chain gemini imidazolium and pyridinium amphiphiles.

    Science.gov (United States)

    Bhadani, Avinash; Kataria, Hardeep; Singh, Sukhprit

    2011-09-01

    Two series of phenoxy ring containing long chain imidazolium and pyridinium based gemini amphiphiles have been synthesized from renewable cardanol oil having different spacers (i. e. -S-(CH(2))(n)-S-, where n is 2, 3, 4 & 6). Critical micelle concentration (cmc) of these new gemini amphiphiles has been determined by conductivity method. Further, these new cationic amphiphiles have been evaluated for their DNA binding capability by agarose gel electrophoresis, ethidium bromide exclusion experiments and transmission electron microscopy (TEM). The cytotoxicity of these new amphiphiles have been evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Comparative studies of these phenoxy ring containing long chain gemini imidazolium amphiphiles and their pyridinium analogues depicted low cmc values of the later but greater DNA interaction capability and low cytotoxicity of the former series of amphiphiles. PMID:21676409

  4. Real-time monitoring of the penetration of amphiphilic acrylate copolymer in leather using a fluorescent copolymer as tracer.

    Science.gov (United States)

    Du, Jin-Xia; Shi, Lu; Peng, Bi-Yu

    2015-12-01

    A fluorescent tracer, poly (acrylic-co-stearyl acrylate-co-3-acryloyl fluorescein) [poly (AA-co-SA-co-Ac-Flu)], used for real-time monitoring the penetration of amphiphilic acrylate copolymer, poly (acrylic-co-stearyl acrylate) [poly (AA-co-SA)], in leather was synthesized by radical polymerization of acrylic, stearyl acrylate and fluorescent monomer, 3-acryloyl fluorescein (Ac-Flu). The structure, molecular weight, introduced fluorescent group content and fluorescent characteristics of the fluorescent tracer and target copolymer, amphiphilic acrylate copolymer, were also characterized. The results show that the tracer presents the similar structural characteristics to the target and enough fluorescence intensity with 1.68 wt % of the fluorescent monomer introduced amount. The vertical section of the leather treated with the target copolymer mixing with 7% of the tracer exhibits evident fluorescence, and the change of fluorescence intensity along with the vertical section with treating time increasing can reflect the penetration depth of the target copolymer. The introduction of the fluorescent group in polymer structure through copolymerization with a limited amount of fluorescent monomer, Ac-Flu, is an effective way to make a tracer to monitor the penetration of the target in leather, which provides a new thought for the penetration research of syntans such as vinyl copolymer materials in leather manufacture.

  5. Strategies for encapsulation of small hydrophilic and amphiphilic drugs in PLGA microspheres: State-of-the-art and challenges.

    Science.gov (United States)

    Ramazani, Farshad; Chen, Weiluan; van Nostrum, Cornelis F; Storm, Gert; Kiessling, Fabian; Lammers, Twan; Hennink, Wim E; Kok, Robbert J

    2016-02-29

    Poly(lactide-co-glycolide) (PLGA) microspheres are efficient delivery systems for controlled release of low molecular weight drugs as well as therapeutic macromolecules. The most common microencapsulation methods are based on emulsification procedures, in which emulsified droplets of polymer and drug solidify into microspheres when the solvent is extracted from the polymeric phase. Although high encapsulation efficiencies have been reported for hydrophobic small molecules, encapsulation of hydrophilic and/or amphiphilic small molecules is challenging due to the partitioning of drug from the polymeric phase into the external phase before solidification of the particles. This review addresses formulation-related aspects for efficient encapsulation of small hydrophilic/amphiphilic molecules into PLGA microspheres using conventional emulsification methods (e.g., oil/water, water/oil/water, solid/oil/water, water/oil/oil) and highlights novel emulsification technologies such as microfluidics, membrane emulsification and other techniques including spray drying and inkjet printing. Collectively, these novel microencapsulation technologies afford production of this type of drug loaded microspheres in a robust and well controlled manner. PMID:26795193

  6. Stealth Amphiphiles: Self-Assembly of Polyhedral Boron Clusters.

    Science.gov (United States)

    Ďorďovič, Vladimír; Tošner, Zdeněk; Uchman, Mariusz; Zhigunov, Alexander; Reza, Mehedi; Ruokolainen, Janne; Pramanik, Goutam; Cígler, Petr; Kalíková, Květa; Gradzielski, Michael; Matějíček, Pavel

    2016-07-01

    This is the first experimental evidence that both self-assembly and surface activity are common features of all water-soluble boron cluster compounds. The solution behavior of anionic polyhedral boranes (sodium decaborate, sodium dodecaborate, and sodium mercaptododecaborate), carboranes (potassium 1-carba-dodecaborate), and metallacarboranes {sodium [cobalt bis(1,2-dicarbollide)]} was extensively studied, and it is evident that all the anionic boron clusters form multimolecular aggregates in water. However, the mechanism of aggregation is dependent on size and polarity. The series of studied clusters spans from a small hydrophilic decaborate-resembling hydrotrope to a bulky hydrophobic cobalt bis(dicarbollide) behaving like a classical surfactant. Despite their pristine structure resembling Platonic solids, the nature of anionic boron cluster compounds is inherently amphiphilic-they are stealth amphiphiles. PMID:27287067

  7. Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles

    Science.gov (United States)

    Qiu, Huibin; Hudson, Zachary M.; Winnik, Mitchell A.; Manners, Ian

    2015-03-01

    Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but on a longer length scale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side by side or end to end in nonsolvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and one-dimensional (1D) or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicrometer-length scale, features that are generally only found in natural materials.

  8. Passivation of nanocrystalline TiO2 junctions by surface adsorbed phosphinate amphiphiles enhances the photovoltaic performance of dye sensitized solar cells

    KAUST Repository

    Wang, Mingkui

    2009-01-01

    We report a new class of molecular insulators that electronically passivate the surface of nanocrystalline titania films for high performance dye sensitized solar cells (DSC). Using electrical impedance measurements we demonstrate that co-adsorption of dineohexyl bis-(3,3-dimethyl-butyl)-phosphinic acid (DINHOP), along with the amphiphilic ruthenium sensitizer Z907Na increased substantially the power output of the cells mainly due to a retardation of interfacial recombination of photo-generated charge carriers. The use of phosphinates as anchoring groups opens up new avenues for modification of the surface by molecular insulators, sensitizers and other electro-active molecules to realize the desired optoelectronic performance of devices based on oxide junctions. © 2009 The Royal Society of Chemistry.

  9. Prebiotic Lipidic Amphiphiles and Condensing Agents on the Early Earth.

    Science.gov (United States)

    Fiore, Michele; Strazewski, Peter

    2016-01-01

    It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of vesicles that, in principle, could have compartmented first biological processes on early Earth, including the emergence of self-replicating systems. For a competitive selection of the best performing molecular replicators to become operative, some kind of bounded units capable of harboring them are indispensable. Without the competition between dynamic populations of different compartments, life itself could not be distinguished from an otherwise disparate array or network of molecular interactions. In this review, we describe experiments that demonstrate how different prebiotically-available building blocks can become precursors of phospholipids that form vesicles. We discuss the experimental conditions that resemble plausibly those of the early Earth (or elsewhere) and consider the analytical methods that were used to characterize synthetic products. Two brief sections focus on phosphorylating agents, catalysts and coupling agents with particular attention given to their geochemical context. In Section 5, we describe how condensing agents such as cyanamide and urea can promote the abiotic synthesis of phospholipids. We conclude the review by reflecting on future studies of phospholipid compartments, particularly, on evolvable chemical systems that include giant vesicles composed of different lipidic amphiphiles. PMID:27043635

  10. Prebiotic Lipidic Amphiphiles and Condensing Agents on the Early Earth

    Directory of Open Access Journals (Sweden)

    Michele Fiore

    2016-03-01

    Full Text Available It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of vesicles that, in principle, could have compartmented first biological processes on early Earth, including the emergence of self-replicating systems. For a competitive selection of the best performing molecular replicators to become operative, some kind of bounded units capable of harboring them are indispensable. Without the competition between dynamic populations of different compartments, life itself could not be distinguished from an otherwise disparate array or network of molecular interactions. In this review, we describe experiments that demonstrate how different prebiotically-available building blocks can become precursors of phospholipids that form vesicles. We discuss the experimental conditions that resemble plausibly those of the early Earth (or elsewhere and consider the analytical methods that were used to characterize synthetic products. Two brief sections focus on phosphorylating agents, catalysts and coupling agents with particular attention given to their geochemical context. In Section 5, we describe how condensing agents such as cyanamide and urea can promote the abiotic synthesis of phospholipids. We conclude the review by reflecting on future studies of phospholipid compartments, particularly, on evolvable chemical systems that include giant vesicles composed of different lipidic amphiphiles.

  11. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    OpenAIRE

    Shrestha, Sanjib K.; Cheng-Wei T Chang; Meissner, Nicole; Oblad, John; Shrestha, Jaya P.; Sorensen, Kevin N.; Michelle M. Grilley; Jon Y Takemoto

    2014-01-01

    K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20′s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were de...

  12. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    OpenAIRE

    Shrestha, Sanjib K.; Cheng-Wei Tom Chang; Nicole eMeissner; John eOblad; Shrestha, Jaya P.; Sorensen, Kevin N.; Michelle M. Grilley; Jon Y Takemoto

    2014-01-01

    K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20’s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were d...

  13. Relation between structure and organisation properties of new amphiphilic cyclodextrins

    International Nuclear Information System (INIS)

    Since a number of years, special attention and efforts have been made to prepare amphiphilic cyclodextrins (CDs) with the objective to use them to obtain supramolecular assemblies as such or in the presence of preformed lipidic structures. The aim of these investigation is in both cases to combine the size specificity of cyclodextrins for guests and the transport properties of phospho-lipidic structures. The final objects could be of importance to transport or target biologically relevant molecules such as drugs using new galenic formulations. In a first step, a new family of amphiphilic CDs was prepared from a pure phospholipids (DMPE) onto cyclodextrins or methylated derivatives through a spacing arm. The afforded compounds (phospholipidyl-cyclodextrins) were fully characterized by high field NMR and high resolution mass spectrometry. The methylated derivatives were shown to self-organize in water with low CMC to form fluctuating micellar fibers retaining the inclusion capacity of the cyclodextrin cavities. The interactions of these compounds with membrane systems were investigated as black films using X-ray reflectivity and by evaluation of their detergent power towards model DMPC liposomes. Their ability to cross over the Blood Brain Barrier was evidenced by a new approach making use of novel immuno-enzymatic assays. In a second step, a new class of amphiphilic cyclodextrins was considered (peptidolipidyl-cyclodextrins). Although they are structurally similar to phospholipidyl-CDs, their preparation overcomes the tedious steps of the later and lead to a considerable versatility in terms of the number of possible molecules to be prepared. Moreover, the stability problems encountered with phospholipids are avoided. Several examples have been prepared, fully characterized and their organization properties investigated by the determination of CMC and by deuterium NMR on a pure and homogeneous mixed peptidolipidyl-CD / DMPC lamellar phase. This novel class of

  14. From Vesicles to Protocells: The Roles of Amphiphilic Molecules

    OpenAIRE

    Yuka Sakuma; Masayuki Imai

    2015-01-01

    It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhes...

  15. A defect mediated lamellar to isotropic transition of amphiphile bilayers

    OpenAIRE

    Pal, Antara; Pabst, Georg; Raghunathan, V. A.

    2011-01-01

    We report the observation of a novel isotropic phase of amphiphile bilayers in a mixed system consisting of the ionic surfactant, sodium docecylsulphate (SDS), and the organic salt p-toludine hydrochloride (PTHC). This system forms a collapsed lamellar ($L_\\alpha$) phase over a wide range of water content, which transforms into an isotropic phase on heating. This transition is not observed in samples without excess water, where the $L_\\alpha$ phase is stable at higher temperatures. Our observ...

  16. The lamellar-to-isotropic transition in ternary amphiphilic systems

    OpenAIRE

    Schwarz, U. S.; Swamy, K.; Gompper, G.

    1996-01-01

    We study the dependence of the phase behavior of ternary amphiphilic systems on composition and temperature. Our analysis is based on a curvature elastic model of the surfactant film with sufficiently large spontaneous curvature and sufficiently negative saddle-splay modulus that the stable phases are the lamellar phase and a droplet microemulsion. In addition to the curvature energy, we consider the contributions to the free energy of the long-ranged van der Waals interaction and of the undu...

  17. Purely peptidic amphiphiles : understanding and controlling their self-assembled structures

    OpenAIRE

    Schuster, Thomas Bernhard

    2011-01-01

    Amphiphilic molecules spontaneously self-assemble into a variety of structures in solution. The term amphiphilic indicates that one part of the molecule is attracted to the solvent, while the other is not. Interactions such as between solute-solvent and solute-solute thus determine the organization. Understanding the self-assembly means understanding those interactions and their driving forces. In the first chapter an overview of the self-organization of amphiphilic molecules into supermolecu...

  18. A STUDY ON LOAD CAPACITY OF HORIZONTAL AND INCLINED PLATE ANCHORS IN SANDY SOILS

    OpenAIRE

    BALESHWAR SINGH; BIRJUKUMAR MISTRI

    2011-01-01

    Foundations of structures which are subjected to uplift loading require anchoring systems to resist pullout loads. Such anchors can be broadly classified as gravity anchors, pile anchors and plate anchors. Plate anchors can be circular, square or strip in shape. The loading applied on plate anchors can be vertical, inclined or horizontal depending on the anchor orientation. In this study, various experimental, theoretical and numerical approaches for estimation of load capacity of horizontal ...

  19. Supramolecular Packing Controls H₂ Photocatalysis in Chromophore Amphiphile Hydrogels.

    Science.gov (United States)

    Weingarten, Adam S; Kazantsev, Roman V; Palmer, Liam C; Fairfield, Daniel J; Koltonow, Andrew R; Stupp, Samuel I

    2015-12-01

    Light harvesting supramolecular assemblies are potentially useful structures as components of solar-to-fuel conversion materials. The development of these functional constructs requires an understanding of optimal packing modes for chromophores. We investigated here assembly in water and the photocatalytic function of perylene monoimide chromophore amphiphiles with different alkyl linker lengths separating their hydrophobic core and the hydrophilic carboxylate headgroup. We found that these chromophore amphiphiles (CAs) self-assemble into charged nanostructures of increasing aspect ratio as the linker length is increased. The addition of salt to screen the charged nanostructures induced the formation of hydrogels and led to internal crystallization within some of the nanostructures. For linker lengths up to seven methylenes, the CAs were found to pack into 2D crystalline unit cells within ribbon-shaped nanostructures, whereas the nine methylene CAs assembled into long nanofibers without crystalline molecular packing. At the same time, the different molecular packing arrangements after charge screening led to different absorbance spectra, despite the identical electronic properties of all PMI amphiphiles. While the crystalline CAs formed electronically coupled H-aggregates, only CAs with intermediate linker lengths showed evidence of high intermolecular orbital overlap. Photocatalytic hydrogen production using a nickel-based catalyst was observed in all hydrogels, with the highest turnovers observed for CA gels having intermediate linker lengths. We conclude that the improved photocatalytic performance of the hydrogels formed by supramolecular assemblies of the intermediate linker CA molecules likely arises from improved exciton splitting efficiencies due to their higher orbital overlap. PMID:26593389

  20. Cationic amphiphiles with fatty acyl chain asymmetry of coconut oil deliver genes selectively to mouse lung.

    Science.gov (United States)

    Chandrashekhar, Voshavar; Srujan, Marepally; Prabhakar, Rairala; Reddy, Rakesh C; Sreedhar, Bojja; Rentam, Kiran K R; Kanjilal, Sanjit; Chaudhuri, Arabinda

    2011-03-16

    Recent structure-activity studies have revealed a dramatic influence of hydrophobic chain asymmetry in enhancing gene delivery efficacies of synthetic cationic amphiphiles (Nantz, M. H. et al. Mol. Pharmaceutics2010, 7, 786-794; Koynova, R. et al. Mol. Pharmaceutics2009, 6, 951-958). The present findings demonstrate for the first time that such a transfection enhancing influence of asymmetric hydrocarbon chains observed in pure synthetic cationic amphiphiles also works for cationic amphiphiles designed with natural, asymmetric fatty acyl chains of a food-grade oil. Herein, we demonstrate that cationic amphiphiles designed with the natural fatty acyl chain asymmetry of food-grade coconut oil are less cytotoxic and deliver genes selectively to mouse lung. Despite lauroyl chains being the major fatty acyl chains of coconut oil, both the in vitro and In vivo gene transfer efficiencies of such cationic amphiphiles were found to be remarkably superior (>4-fold) to those of their pure dilauroyl analogue. Mechanistic studies involving the technique of fluorescence resonance energy transfer (FRET) revealed higher biomembrane fusibility of the cationic liposomes of the coconut amphiphiles than that of the symmetric dilauroyl analogue. AFM study revealed pronounced fusogenic nonlamellar structures of the liposomes of coconut amphiphiles. Findings in the FRET and cellular uptake study, taken together, support the notion that the higher cellular uptake resulting from the more fusogenic nature of the liposomes of coconut amphiphiles 1 are likely to play a dominant role in making the coconut amphiphiles transfection competent.

  1. Self-assembly of amphiphilic molecules:A review on the recent computer simulation results

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We provided a short review on the recent progresses in computer simulations of adsorption and self-assembly of amphiphilic molecules.Owing to the extensive applications of amphiphilic molecules,it is very important to understand thoroughly the effects of the detailed chemistry,solid surfaces and the degree of confinement on the aggregate morphologies and kinetics of self-assembly for amphiphilic systems.In this review we paid special attention on(i) morphologies of adsorbed surfactants on solid surfaces,(ii) self-assembly in confined systems,and(iii) kinetic processes involving amphiphilic molecules.

  2. Stable and robust polymer nanotubes stretched from polymersomes

    OpenAIRE

    Reiner, Joseph E.; Jeffrey M. Wells; Kishore, Rani B.; Pfefferkorn, Candace; Helmerson, Kristian

    2006-01-01

    We create long polymer nanotubes by directly pulling on the membrane of polymersomes using either optical tweezers or a micropipette. The polymersomes are composed of amphiphilic diblock copolymers, and the nanotubes formed have an aqueous core connected to the aqueous interior of the polymersome. We stabilize the pulled nanotubes by subsequent chemical cross-linking. The cross-linked nanotubes are extremely robust and can be moved to another medium for use elsewhere. We demonstrate the abili...

  3. Geodesic defect anchoring on nematic shells.

    Science.gov (United States)

    Mirantsev, Leonid V; Sonnet, André M; Virga, Epifanio G

    2012-08-01

    Nematic shells are colloidal particles coated with nematic liquid crystal molecules, which may freely glide and rotate on the colloid's surface while keeping their long axis on the local tangent plane. Molecular dynamics simulations on a nanoscopic spherical shell indicate that under appropriate adhesion conditions for the molecules on the equator, the equilibrium nematic texture exhibits at each pole a pair of +1/2 defects so close to one another to be treated as one +1 defect. Spirals connect the polar defects, though the continuum limit of the interaction potential would not feature any elastic anisotropy. A molecular averaging justifies an anchoring defect energy that feels the geodesics emanating from the defect. All our observations are explained by such a geodesic anchoring, which vanishes on flat manifolds. PMID:23005713

  4. Composite materials formed with anchored nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

    2015-03-10

    A method of forming nano-structure composite materials that have a binder material and a nanostructure fiber material is described. A precursor material may be formed using a mixture of at least one metal powder and anchored nanostructure materials. The metal powder mixture may be (a) Ni powder and (b) NiAl powder. The anchored nanostructure materials may comprise (i) NiAl powder as a support material and (ii) carbon nanotubes attached to nanoparticles adjacent to a surface of the support material. The process of forming nano-structure composite materials typically involves sintering the mixture under vacuum in a die. When Ni and NiAl are used in the metal powder mixture Ni.sub.3Al may form as the binder material after sintering. The mixture is sintered until it consolidates to form the nano-structure composite material.

  5. An Analytical Method for Positioning Drag Anchors in Seabed Soils

    Institute of Scientific and Technical Information of China (English)

    张炜; 刘海笑; 李新仲; 李清平; 曹静

    2015-01-01

    Positioning drag anchors in seabed soils are strongly influenced not only by the properties of the anchor and soil, but also by the characteristics of the installation line. The investigation on the previous prediction methods related to anchor positioning demonstrates that the prediction of the anchor position during dragging has inevitably introduced some key and unsubstantiated hypotheses and the applicability of these methods is limited. In the present study, the interactional system between the drag anchor and installation line is firstly introduced for the analysis of anchor positioning. Based on the two mechanical models for embedded lines and drag anchors, the positioning equations for drag anchors have been derived both for cohesive and noncohesive soils. Since the drag angle at the shackle is the most important parameter in the positioning equations, a novel analytical method that can predict both the variation and the exact value of the drag angle at the shackle is proposed. The analytical method for positioning drag anchors which combines the interactional system between the drag anchor and the installation line has provided a reasonable theoretic approach to investigate the anchor behaviors in soils. By comparing with the model flume experiments, the sensitivity, effectiveness and veracity of the positioning method are well verified.

  6. Recent Study of Drag Embedment Plate Anchors in China

    Institute of Scientific and Technical Information of China (English)

    Haixiao Liu

    2012-01-01

    Experimental and theoretical studies of drag embedment plate anchors recently carried out in Tianjin University are summarized in this research paper,which involve a series of important topics relevant to the study of drag anchors.The techniques for measuring the trajectory and movement direction of drag anchors in soils,the techniques for measuring the moving embedment point and reverse catenary shape of the embedded drag line,the penetration mechanism and kinematic behavior of drag anchors,the ultimate embedment depth of drag anchors,the movement direction of the anchor with an arbitrary fluke section,the reverse catenary properties of the embedded drag line,the interactional properties between drag anchor and installation line,the kinematic model of drag anchors in seabed soils,and the analytical method for predicting the anchor trajectory in soils will all be examined.The present work remarkably reduces the uncertainties in design and analysis of drag embedment plate anchors,and is beneficial to improving the application of this new type of drag anchor in offshore engineering.

  7. The Effect of Molecular Anchoring and Curvature on Confined Liquid Crystals

    Science.gov (United States)

    Ondris-Crawford, Renate Johanna

    of the liquid crystal material. The investigation of stable nematic director-fields in supramicrometer droplets with tangential (bipolar droplets) and homeotropic anchoring (axial and radial droplet) encompassed simulating optical birefringence patterns computed from Frank elastic theory and comparing these to the observed textures of polymer dispersed liquid crystal droplets.

  8. Vertical and lateral capacity of screw anchor piles

    Energy Technology Data Exchange (ETDEWEB)

    Law, D.J.; Tweedie, R.W.; Harris, M.C. [Thurber Engineering Ltd., Edmonton, AB (Canada); Niedermaier, J. [Alberta Anchor Inc., Calgary, AB (Canada)

    1996-09-01

    Test programs were conducted to investigate the deformation behaviour of screw anchors during loading. Screw anchors are used in foundation applications for transmission towers and retaining walls, as well as for foundation elements for buildings, pipe racks, storage tanks and equipment. Screw anchor piles were installed at a site near Fort Saskatchewan, at a site underlain by typical stiff glacial soils. Single and multi-helix screw anchors with helix diameters up to 381 mm were tested in compression and tension. Lateral load tests were conducted on screw anchors with shaft diameters ranging from 114 mm to 273 mm. Results from the study showed that vertical and horizontal loads can be carried by screw anchor piles that are comparable with those achieved with driven steel piles, but screw anchors are easier to install, and can be more cost effective in some cases. 4 refs., 3 tabs., 4 figs.

  9. Anchoring properties of substrate with a grating surface

    Institute of Scientific and Technical Information of China (English)

    Ye Wen-Jiang; Xing Hong-Yu; Yang Guo-Chen

    2007-01-01

    The anchoring properties of substrate with a grating surface are investigated analytically. The alignment of nematic liquid crystal (NLC) in a grating surface originates from two mechanisms, thus the anchoring energy consists of two parts. One originates from the interaction potential between NLC molecules and the molecules on the substrate surface,and the other stems from the increased elastic strain energy. Based on the two mechanisms, the expression of anchoring energy per unit area of a projected plane of this grating surface is deduced and called the equivalent anchoring energy formula. Both the strength and the easy direction of equivalent anchoring energy are a function of the geometrical parameters (amplitude and pitch) of a grating surface. By using this formula, the grating surface can be replaced by its projected plane and its anchoring properties can be described by the equivalent anchoring energy formula.

  10. Anchoring in a novel bimanual coordination pattern.

    Science.gov (United States)

    Maslovat, Dana; Lam, Melanie Y; Brunke, Kirstin M; Chua, Romeo; Franks, Ian M

    2009-02-01

    Anchoring in cyclical movements has been defined as regions of reduced spatial or temporal variability [Beek, P. J. (1989). Juggling dynamics. PhD thesis. Amsterdam: Free University Press] that are typically found at movement reversal points. For in-phase and anti-phase movements, synchronizing reversal points with a metronome pulse has resulted in decreased anchor point variability and increased pattern stability [Byblow, W. D., Carson, R. G., & Goodman, D. (1994). Expressions of asymmetries and anchoring in bimanual coordination. Human Movement Science, 13, 3-28; Fink, P. W., Foo, P., Jirsa, V. K., & Kelso, J. A. S. (2000). Local and global stabilization of coordination by sensory information. Experimental Brain Research, 134, 9-20]. The present experiment examined anchoring during acquisition, retention, and transfer of a 90 degrees phase-offset continuous bimanual coordination pattern (whereby the right limb lags the left limb by one quarter cycle), involving horizontal flexion about the elbow. Three metronome synchronization strategies were imposed: participants either synchronized maximal flexion of the right arm (i.e., single metronome), both flexion and extension of the right arm (i.e., double metronome within-limb), or flexion of each arm (i.e., double metronome between-limb) to an auditory metronome. In contrast to simpler in-phase and anti-phase movements, synchronization of additional reversal points to the metronome did not reduce reversal point variability or increase pattern stability. Furthermore, practicing under different metronome synchronization strategies did not appear to have a significant effect on the rate of acquisition of the pattern. PMID:18842313

  11. Anchoring Heuristic and the Equity Premium Puzzle

    OpenAIRE

    Siddiqi, Hammad

    2015-01-01

    What happens when the anchoring and adjustment heuristic of Tversky and Kahneman (1974) is incorporated in the standard consumption-based capital asset pricing model (CCAPM)? The surprising finding is that it not only resolves the high equity-premium and low risk-free rate puzzles with a low risk-aversion coefficient, but also provides a unified framework for understanding countercyclical equity-premium, excess volatility, size, value, and momentum effects, and abnormal returns and volatiliti...

  12. Anchor Toolkit - a secure mobile agent system

    OpenAIRE

    Mudumbai, Srilekha S.; Johnston, William; Essiari, Abdelilah

    2008-01-01

    Mobile agent technology facilitates intelligent operation in software systems with less human interaction. Major challenge to deployment of mobile agents include secure transmission of agents and preventing unauthorized access to resources between interacting systems, as either hosts, or agents, or both can act maliciously. The Anchor toolkit, designed by LBNL, handles the transmission and secure management of mobile agents in a heterogeneous distributed computing environment. It provide...

  13. Test Score Equating Using a Mini-Version Anchor and a Midi Anchor: A Case Study Using SAT[R] Data

    Science.gov (United States)

    Liu, Jinghua; Sinharay, Sandip; Holland, Paul W.; Curley, Edward; Feigenbaum, Miriam

    2011-01-01

    This study explores an anchor that is different from the traditional miniature anchor in test score equating. In contrast to a traditional "mini" anchor that has the same spread of item difficulties as the tests to be equated, the studied anchor, referred to as a "midi" anchor (Sinharay & Holland), has a smaller spread of item difficulties than…

  14. Anchored design of protein-protein interfaces.

    Directory of Open Access Journals (Sweden)

    Steven M Lewis

    Full Text Available BACKGROUND: Few existing protein-protein interface design methods allow for extensive backbone rearrangements during the design process. There is also a dichotomy between redesign methods, which take advantage of the native interface, and de novo methods, which produce novel binders. METHODOLOGY: Here, we propose a new method for designing novel protein reagents that combines advantages of redesign and de novo methods and allows for extensive backbone motion. This method requires a bound structure of a target and one of its natural binding partners. A key interaction in this interface, the anchor, is computationally grafted out of the partner and into a surface loop on the design scaffold. The design scaffold's surface is then redesigned with backbone flexibility to create a new binding partner for the target. Careful choice of a scaffold will bring experimentally desirable characteristics into the new complex. The use of an anchor both expedites the design process and ensures that binding proceeds against a known location on the target. The use of surface loops on the scaffold allows for flexible-backbone redesign to properly search conformational space. CONCLUSIONS AND SIGNIFICANCE: This protocol was implemented within the Rosetta3 software suite. To demonstrate and evaluate this protocol, we have developed a benchmarking set of structures from the PDB with loop-mediated interfaces. This protocol can recover the correct loop-mediated interface in 15 out of 16 tested structures, using only a single residue as an anchor.

  15. Polymer fractionation

    Energy Technology Data Exchange (ETDEWEB)

    Hadermann, A. F.

    1985-04-09

    Soluble polymers are fractionated according to molecular weight by cryogenically comminuting the polymer and introducing the polymer particles, while still in the active state induced by cryogenic grinding, into a liquid having a solvent power selected to produce a coacervate fraction containing high molecular weight polymer species and a dilute polymer solution containing lower molecular weight polymer species. The coacervate may be physically separated from the solution and finds use in the production of antimisting jet fuels and the like.

  16. Impact of Photo-Induced Surface Adsorption of Azo-Dyes on the Liquid Crystal Anchoring Conditions

    Science.gov (United States)

    Statman, David

    2013-03-01

    Using optical techniques, we measured the anchoring conditions of azo-dye doped nematic liquid crystals on rubbed polyimide surfaces. Linearly polarized light induces the formation of a second easy axis on the polymer surface oriented toward the polarization direction of the pump laser beam. This additional easy axis is the result of photo-induced adsorption of the cis isomer of the azo dye. An effective easy axis is the weighted average of the original easy axis and this new easy axis.

  17. Interaction of multiple biomimetic antimicrobial polymers with model bacterial membranes

    Energy Technology Data Exchange (ETDEWEB)

    Baul, Upayan, E-mail: upayanb@imsc.res.in; Vemparala, Satyavani, E-mail: vani@imsc.res.in [The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai 600113 (India); Kuroda, Kenichi, E-mail: kkuroda@umich.edu [Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan 48109 (United States)

    2014-08-28

    Using atomistic molecular dynamics simulations, interaction of multiple synthetic random copolymers based on methacrylates on prototypical bacterial membranes is investigated. The simulations show that the cationic polymers form a micellar aggregate in water phase and the aggregate, when interacting with the bacterial membrane, induces clustering of oppositely charged anionic lipid molecules to form clusters and enhances ordering of lipid chains. The model bacterial membrane, consequently, develops lateral inhomogeneity in membrane thickness profile compared to polymer-free system. The individual polymers in the aggregate are released into the bacterial membrane in a phased manner and the simulations suggest that the most probable location of the partitioned polymers is near the 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) clusters. The partitioned polymers preferentially adopt facially amphiphilic conformations at lipid-water interface, despite lacking intrinsic secondary structures such as α-helix or β-sheet found in naturally occurring antimicrobial peptides.

  18. FragAnchor: A Large-Scale Predictor of Glycosylphosphatidylinositol Anchors in Eukaryote Protein Sequences by Qualitative Scoring

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A glycosylphosphatidylinositol (GPI) anchor is a common but complex C-terminal post-translational modification of extracellular proteins in eukaryotes. Here we investigate the problem of correctly annotating GPI-anchored proteins for the growing number of sequences in public databases. We developed a computational system, called FragAnchor, based on the tandem use of a neural network (NN) and a hidden Markov model (HMM). Firstly, NN selects potential GPI-anchored proteins in a dataset, then HMM parses these potential GPI signals and refines the prediction by qualitative scoring. FragAnchor correctly predicted 91% of all the GPI-anchored proteins annotated in the Swiss-Prot database.In a large-scale analysis of 29 eukaryote proteomes, FragAnchor predicted that the percentage of highly probable GPI-anchored proteins is between 0.21% and 2.01%. The distinctive feature of FragAnchor, compared with other systems,is that it targets only the C-terminus of a protein, making it less sensitive to the background noise found in databases and possible incomplete protein sequences. Moreover, FragAnchor can be used to predict GPI-anchored proteins in all eukaryotes. Finally, by using qualitative scoring, the predictions combine both sensitivity and information content. The predictor is publicly available at http: // navet. ics. hawaii.edu/~fraganchor/NNHMM/NNHMM.html.

  19. Robotic Ankle for Omnidirectional Rock Anchors

    Science.gov (United States)

    Parness, Aaron; Frost, Matthew; Thatte, Nitish

    2013-01-01

    Future robotic exploration of near-Earth asteroids and the vertical and inverted rock walls of lava caves and cliff faces on Mars and other planetary bodies would require a method of gripping their rocky surfaces to allow mobility without gravitational assistance. In order to successfully navigate this terrain and drill for samples, the grippers must be able to produce anchoring forces in excess of 100 N. Additionally, the grippers must be able to support the inertial forces of a moving robot, as well gravitational forces for demonstrations on Earth. One possible solution would be to use microspine arrays to anchor to rock surfaces and provide the necessary load-bearing abilities for robotic exploration of asteroids. Microspine arrays comprise dozens of small steel hooks supported on individual suspensions. When these arrays are dragged along a rock surface, the steel hooks engage with asperities and holes on the surface. The suspensions allow for individual hooks to engage with asperities while the remaining hooks continue to drag along the surface. This ensures that the maximum possible number of hooks engage with the surface, thereby increasing the load-bearing abilities of the gripper. Using the microspine array grippers described above as the end-effectors of a robot would allow it to traverse terrain previously unreachable by traditional wheeled robots. Furthermore, microspine-gripping robots that can perch on cliffs or rocky walls could enable a new class of persistent surveillance devices for military applications. In order to interface these microspine grippers with a legged robot, an ankle is needed that can robotically actuate the gripper, as well as allow it to conform to the large-scale irregularities in the rock. The anchor serves three main purposes: deploy and release the anchor, conform to roughness or misalignment with the surface, and cancel out any moments about the anchor that could cause unintentional detachment. The ankle design contains a

  20. Dehydration-induced redistribution of amphiphilic molecules between cytoplasm and lipids is associated with desiccation tolerance in seeds

    NARCIS (Netherlands)

    Buitink, J.; Leprince, O.; Hoekstra, F.A.

    2000-01-01

    This study establishes a relationship between desiccation tolerance and the transfer of amphiphilic molecules from the cytoplasm into lipids during drying, using electron paramagnetic resonance spectroscopy of amphiphilic spin probes introduced into imbibed radicles of pea (Pisum sativum) and cucumb

  1. Self-assembled amphiphilic polyhedral oligosilsesquioxane (POSS) grafted poly(vinyl alcohol) (PVA) nanoparticles

    International Nuclear Information System (INIS)

    In the present study, spherical nanoparticles (NPs) containing polyhedral oligosilsesquioxane (POSS) as an inner hydrophobic core and poly(vinyl alcohol) PVA as a hydrophilic outer shell were prepared by dialysis approach. Preparation of amphiphilic POSS-grafted-PVA co-polymer was characterized by 1H NMR and FT-IR. The results indicated urethane linkage between monoisocyanate group of POSS macromer and the hydroxyl groups of PVA. The dynamic light scattering (DLS) and electrophoretic light scattering (ELS) of the NPs revealed that they have an average hydrodynamic diameter and negative zeta (ζ)-potential of 215 nm and - 161 mV, respectively. Atomic force microscopy (AFM) and bio-transmission electron microscope (BIO-TEM) have shown unagglomerated NPs within a diameter range of 60-90 nm. The prepared NPs were investigated to improve the control release of anticancer drug; paclitaxel as a model drug. Due to drug loading, the hydrodynamic diameter and negative zeta (ζ)-potential have changed to 325 nm and - 14 mV, respectively. In addition, in-vitro drug release experiments were conducted; the obtained results explicated continuous release for over 40 days. However, in case of using pure drug only, the drug completely released within 1 h.

  2. Dynamic performance of concrete undercut anchors for Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Mahrenholtz, Christoph, E-mail: christoph@mahrenholtz.net; Eligehausen, Rolf

    2013-12-15

    Graphical abstract: - Highlights: • Behavior of undercut anchors under dynamic actions simulating earthquakes. • First high frequency load and crack cycling tests on installed concrete anchors ever. • Comprehensive review of anchor qualification for Nuclear Power Plants. - Abstract: Post-installed anchors are widely used for structural and nonstructural connections to concrete. In many countries, concrete anchors used for Nuclear Power Plants have to be qualified to ensure reliable behavior even under extreme conditions. The tests required for qualification of concrete anchors are carried out at quasi-static loading rates well below the rates to be expected for dynamic actions deriving from earthquakes, airplane impacts or explosions. To investigate potentially beneficial effects of high loading rates and cycling frequencies, performance tests on installed undercut anchors were conducted. After introductory notes on anchor technology and a comprehensive literature review, this paper discusses the qualification of anchors for Nuclear Power Plants and the testing carried out to quantify experimentally the effects of dynamic actions on the load–displacement behavior of undercut anchors.

  3. Analysis of Glenoid Inter-anchor Distance with an All-Suture Anchor System

    Science.gov (United States)

    Kramer, Jonathan; Robinson, Sean; Dutton, Pascual; Dickinson, Ephraim; Rodriguez, John Paul; Camisa, William; Leasure, Jeremi M.; Montgomery, William H.

    2016-01-01

    Objectives: Arthroscopic shoulder stabilization using suture anchors are commonly used techniques. More recently developed all-suture systems employ smaller diameter anchors, which increase repair contact area and allow greater placement density on narrow surfaces such as the glenoid. Our goal is investigate the strength characteristics of various inter-anchor distances in a human glenoid model. Methods: Twelve fresh-frozen human cadaveric glenoids were potted after the labrum was excised. The glenoids were then implanted with 1.4 mm all-suture anchors (Juggerknot, Biomet, Warsaw, IN) at varying inter-anchor distances. Anchors were implanted adjacent to one another or at 2 mm, 3 mm, or 5 mm distances using a template with pre-drilled holes. The glenoids were then underwent single cycle pullout testing using a test frame (Instron 8521, Instron Inc., Norwood, MA). A 5 N preload was applied to the construct and the actuator was driven away from the shoulder at a rate of 12.5mm/s as seen in Figure 1. Force and displacement were collected from the test frame actuator at a rate of 500 Hz. The primary outcomes were failure strength and stiffness. Stiffness was calculated from the initial linear region of the force displacement curve. Failure strength was defined as the first local maximum inflection point in the force displacement curve. Results: During load to fail testing, all but three of the specimens had both anchors pull out of the glenoid. The other mode of failure included one or both of the sutures failing. Stiffness was 13.52 ± 3.8, 17.97 ± 5.02, 17.59 ± 4.65 and 18.95 ± 4.67 N/mm for the adjacent, 2 mm, 3 mm and 5 mm treatment groups as shown Table 1. The adjacent group had a significantly lower stiffness compared to the other treatment groups. Failure strength was 48.68 ± 20.64, 76.16 ± 23.78, 73.19 ± 35.83 and 87.04 ± 34.67 N for the adjacent, 2 mm, 3 mm and 5 mm treatment groups as shown in Table 1. The adjacent group had a significantly lower

  4. Composition and method for self-assembly and mineralization of peptide-amphiphiles

    Science.gov (United States)

    Stupp, Samuel I.; Beniash, Elia; Hartgerink, Jeffrey D.

    2012-02-28

    The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

  5. Composition and method for self-assembly and mineralization of peptide amphiphiles

    Science.gov (United States)

    Stupp, Samuel I.; Beniash, Elia; Hartgerink, Jeffrey D.

    2009-06-30

    The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

  6. Stable Vesicles Composed of Mono- or Dicarboxylic Fatty Acids and Trimethylammonium Amphiphiles

    DEFF Research Database (Denmark)

    Caschera, Filippo; Bernardino de la Serna, Jorge; Löffler, Philipp M. G.;

    2011-01-01

    The self-assembly of cationic and anionic amphiphile mixtures into vesicles in aqueous media was studied using two different systems: i) decanoic acid and trimethyldecylammonium bromide ii) hexadecanedioic acid (a simple bola-amphiphile) and trimethyldecylammonium bromide. The resulting vesicles ...

  7. Phosphate bioisostere containing amphiphiles: a novel class of squaramide-based lipids.

    Science.gov (United States)

    Saha, Abhishek; Panda, Subhankar; Paul, Saurav; Manna, Debasis

    2016-07-19

    We describe a novel class of amphiphiles with squaramide moiety as a phosphate bioisostere. Most synthesized squaramide-based amphiphiles have the favorable physicochemical properties of lipids, such as: formation of stable liposomes or giant unilamellar vesicles in aqueous solution, high phase-transition temperature, low vesicle leakage and phospholipase resistance properties. PMID:27377058

  8. Sliding planar anchoring and viscous surface torque in a cholesteric liquid crystal

    Science.gov (United States)

    Oswald, Patrick; Dequidt, Alain; Żywociński, Andrzej

    2008-06-01

    We propose a surface treatment allowing one to obtain a sliding planar anchoring of nematic (or cholesteric) liquid crystals. It consists of depositing a thin layer of the polymercaptan hardener of an epoxy resin on an isotropic substrate (bare or ITO-coated glass plates). Microscopic observations of defect annihilations and capacitance measurements show that the molecules align parallel to the surface and slide viscously on it when they change orientation, which implies a zero (or extremely small) azimuthal anchoring energy. In contrast, the zenithal anchoring energy Wθ is found to be larger than 3×10-5J/m2 . We also measured the liquid crystal rotational surface viscosity γS by a thermo-optical method using the large temperature variation of the pitch of a compensated cholesteric mixture. We found that the sliding length γS/γ1 (where γ1 is the bulk rotational viscosity) is very large in comparison with the length of a liquid crystal molecule. This result is explained by a simple model which takes into account the diffusion of the liquid crystal within the polymer layer.

  9. Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Isabelle Vroman

    2009-04-01

    Full Text Available Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources or from biological resources (renewable resources. In general natural polymers offer fewer advantages than synthetic polymers. The following review presents an overview of the different biodegradable polymers that are currently being used and their properties, as well as new developments in their synthesis and applications.

  10. Polymer electronics

    CERN Document Server

    Hsin-Fei, Meng

    2013-01-01

    Polymer semiconductor is the only semiconductor that can be processed in solution. Electronics made by these flexible materials have many advantages such as large-area solution process, low cost, and high performance. Researchers and companies are increasingly dedicating time and money in polymer electronics. This book focuses on the fundamental materials and device physics of polymer electronics. It describes polymer light-emitting diodes, polymer field-effect transistors, organic vertical transistors, polymer solar cells, and many applications based on polymer electronics. The book also disc

  11. From Vesicles to Protocells: The Roles of Amphiphilic Molecules

    Directory of Open Access Journals (Sweden)

    Yuka Sakuma

    2015-03-01

    Full Text Available It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life.

  12. From vesicles to protocells: the roles of amphiphilic molecules.

    Science.gov (United States)

    Sakuma, Yuka; Imai, Masayuki

    2015-01-01

    It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures) and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life. PMID:25738256

  13. Identification of new members within suites of amphiphilic marine siderophores

    OpenAIRE

    Vraspir, Julia M.; Holt, Pamela D.; Butler, Alison

    2010-01-01

    Marine bacterial isolates Vibrio sp. HC0601C5 and Halomonas meridiana str. HC4321C1 were isolated off the coast of southern California and were found to produce an expanded suite of previously identified amphiphilic siderophores. Specifically two new members of the amphibactin family, amphibactins S and T, which have a C14:1 ω-7 fatty acid and a saturated C12 fatty acid, respectively, were produced by Vibrio sp. HC0601C5. These siderophores are produced in addition to a number of previously d...

  14. Endocytosis of glycosylphosphatidylinositol-anchored proteins

    Directory of Open Access Journals (Sweden)

    Sabharanjak Shefali

    2009-10-01

    Full Text Available Abstract Glycosylphosphatidylinositol-anchored proteins (GPI-APs represent an interesting amalgamation of the three basic kinds of cellular macromolecules viz. proteins, carbohydrates and lipids. An unusually hybrid moiety, the GPI-anchor is expressed in a diverse range of organisms from parasites to mammalian cells and serves to anchor a large number of functionally diverse proteins and has been the center of attention in scientific debate for some time now. Membrane organization of GPI-APs into laterally-organized cholesterol-sphingolipid ordered membrane domains or "rafts" and endocytosis of GPI-APs has been intensely debated. Inclusion into or exclusion from these membrane domains seems to be the critical factor in determining the endocytic mechanisms and intracellular destinations of GPI-APs. The intracellular signaling as well as endocytic trafficking of GPI-APs is critically dependent upon the cell surface organization of GPI-APs, and the associations with these lipid rafts play a vital role during these processes. The mechanism of endocytosis for GPI-APs may differ from other cellular endocytic pathways, such as those mediated by clathrin-coated pits (caveolae, and is necessary for unique biological functions. Numerous intracellular factors are involved in and regulate the endocytosis of GPI-APs, and these may be variably dependent on cell-type. The central focus of this article is to describe the significance of the endocytosis of GPI-APs on a multitude of biological processes, ranging from nutrient-uptake to more complex immune responses. Ultimately, a thorough elucidation of GPI-AP mediated signaling pathways and their regulatory elements will enhance our understanding of essential biological processes and benefit as components of disease intervention strategies.

  15. Chain length dependence of non-surface activity and micellization behavior of cationic amphiphilic diblock copolymers.

    Science.gov (United States)

    Ghosh, Arjun; Yusa, Shin-ichi; Matsuoka, Hideki; Saruwatari, Yoshiyuki

    2014-04-01

    The cationic and anionic amphiphilic diblock copolymers with a critical chain length and block ratio do not adsorb at the air/water interface but form micelles in solution, which is a phenomenon called "non-surface activity". This is primarily due to the high charge density of the block copolymer, which creates a strong image charge effect at the air/water interface preventing adsorption. Very stable micelle formation in bulk solution could also play an important role in the non-surface activity. To further confirm these unique properties, we studied the adsorption and micellization behavior of cationic amphiphilic diblock copolymers of poly(n-butyl acrylate)-b-poly(3-(methacryloyloxy)ethyl)trimethylammonium chloride) (PBA-b-PDMC) with different molecular weights of hydrophobic blocks but with the same ionic block length. These block copolymers were successfully prepared via consecutive reversible addition-fragmentation chain transfer (RAFT) polymerization. The block copolymer with the shortest hydrophobic block length was surface-active; the solution showed surface tension reduction and foam formation. However, above the critical block ratio, the surface tension of the solution did not decrease with increasing polymer concentration, and there was no foam formation, indicating lack of surface activity. After addition of 0.1 M NaCl, stable foam formation and slight reduction of surface tension were observed, which is reminiscent of the electrostatic nature of the non-surface activity. Fluorescence and dynamic and static light scattering measurements showed that the copolymer with the shortest hydrophobic block did not form micelles, while the block copolymers formed spherical micelles having radii of 25-30 nm. These observations indicate that micelle formation is also important for non-surface activity. Upon addition of NaCl, cmc did not decrease but rather increased as observed for non-surface-active block copolymers previously studied. The micelles formed were

  16. Adsorption phenomena and anchoring energy in nematic liquid crystals

    CERN Document Server

    Barbero, Giovanni

    2005-01-01

    Despite the large quantity of phenomenological information concerning the bulk properties of nematic phase liquid crystals, little is understood about the origin of the surface energy, particularly the surface, interfacial, and anchoring properties of liquid crystals that affect the performance of liquid crystal devices. Self-contained and unique, Adsorption Phenomena and Anchoring Energy in Nematic Liquid Crystals provides an account of new and established results spanning three decades of research into the problems of anchoring energy and adsorption phenomena in liquid crystals.The book contains a detailed discussion of the origin and possible sources of anchoring energy in nematic liquid crystals, emphasizing the dielectric contribution to the anchoring energy in particular. Beginning with fundamental surface and anchoring properties of liquid crystals and the definition of the nematic phase, the authors explain how selective ion adsorption, dielectric energy density, thickness dependence, and bias voltage...

  17. Anchor Toolkit - a secure mobile agent system

    Energy Technology Data Exchange (ETDEWEB)

    Mudumbai, Srilekha S.; Johnston, William; Essiari, Abdelilah

    1999-05-19

    Mobile agent technology facilitates intelligent operation insoftware systems with less human interaction. Major challenge todeployment of mobile agents include secure transmission of agents andpreventing unauthorized access to resources between interacting systems,as either hosts, or agents, or both can act maliciously. The Anchortoolkit, designed by LBNL, handles the transmission and secure managementof mobile agents in a heterogeneous distributed computing environment. Itprovides users with the option of incorporating their security managers.This paper concentrates on the architecture, features, access control anddeployment of Anchor toolkit. Application of this toolkit in a securedistributed CVS environment is discussed as a case study.

  18. Rheological Properties of Associative Star Polymers in Aqueous Solutions: Effect of Hydrophobe Length and Polymer Topology

    DEFF Research Database (Denmark)

    Hietala, Sami; Strandman, Satu; Jarvi, Paula;

    2009-01-01

    Rheological properties of aqueous solutions of well-defined four-armed amphiphilic star block copolymers, poly(acrylic acid)-block-polystyrene (PAA-b-PS)(4), were investigated as a function of the length of the PS blocks, polymer concentration, and temperature and compared with a corresponding...... triblock copolymer. These polymers, synthesized by atom transfer radical polymerization (ATRP), were found to form hydrogels due to intermolecular association originating from the PS blocks. The increasing length of the PS block was observed to lead to more elastic networks due to increased hydrophobic...... interaction. Polymers bearing shorter PS blocks gave gels with relatively long linear response followed by strain hardening before shear thinning while the longer PS blocks lead to formation of elastic but brittle gels with limited linear regime before shear thinning. Star-block copolymers showed more elastic...

  19. Anchor-induced chondral damage in the hip

    Science.gov (United States)

    Matsuda, Dean K.; Bharam, Srino; White, Brian J.; Matsuda, Nicole A.; Safran, Marc

    2015-01-01

    The purpose of this study is to investigate the outcomes from anchor-induced chondral damage of the hip, both with and without frank chondral penetration. A multicenter retrospective case series was performed of patients with chondral deformation or penetration during initial hip arthroscopic surgery. Intra-operative findings, post-surgical clinical courses, hip outcome scores and descriptions of arthroscopic treatment in cases requiring revision surgery and anchor removal are reported. Five patients (three females) of mean age 32 years (range, 16–41 years) had documented anchor-induced chondral damage with mean 3.5 years (range, 1.5–6.0 years) follow-up. The 1 o'clock position (four cases) and anterior and mid-anterior portals (two cases each) were most commonly implicated. Two cases of anchor-induced acetabular chondral deformation without frank penetration had successful clinical and radiographic outcomes, while one case progressed from deformation to chondral penetration with clinical worsening. Of the cases that underwent revision hip arthroscopy, all three had confirmed exposed hard anchors which were removed. Two patients have had clinical improvement and one patient underwent early total hip arthroplasty. Anchor-induced chondral deformation without frank chondral penetration may be treated with close clinical and radiographic monitoring with a low threshold for revision surgery and anchor removal. Chondral penetration should be treated with immediate removal of offending hard anchor implants. Preventative measures include distal-based portals, small diameter and short anchors, removable hard anchors, soft suture-based anchors, curved drill and anchor insertion instrumentation and attention to safe trajectories while visualizing the acetabular articular surface. PMID:27011815

  20. The impact of anchoring bias in the UK equity market

    OpenAIRE

    Koskinen, Matti

    2013-01-01

    PURPOSE OF THE STUDY The purpose of this thesis is to study how the anchoring bias, a cognitive bias, affects equity analysts' forecasts and what kind of implications this bias has for investors and managers of listed companies in the UK stock market. I test whether industry median forecast earnings per share can work as an anchor when analysts are estimating companies' future earnings and how this potential anchoring affects forecast errors, future stock returns, earnings surprises and s...

  1. Decoding Cytoskeleton-Anchored and Non-Anchored Receptors from Single-Cell Adhesion Force Data.

    Science.gov (United States)

    Sariisik, Ediz; Popov, Cvetan; Müller, Jochen P; Docheva, Denitsa; Clausen-Schaumann, Hauke; Benoit, Martin

    2015-10-01

    Complementary to parameters established for cell-adhesion force curve analysis, we evaluated the slope before a force step together with the distance from the surface at which the step occurs and visualized the result in a two-dimensional density plot. This new tool allows detachment steps of long membrane tethers to be distinguished from shorter jumplike force steps, which are typical for cytoskeleton-anchored bonds. A prostate cancer cell line (PC3) immobilized on an atomic-force-microscopy sensor interacted with three different substrates: collagen-I (Col-I), bovine serum albumin, and a monolayer of bone marrow-derived stem cells (SCP1). To address PC3 cells' predominant Col-I binding molecules, an antibody-blocking β1-integrin was used. Untreated PC3 cells on Col-I or SCP1 cells, which express Col-I, predominantly showed jumps in their force curves, while PC3 cells on bovine-serum-albumin- and antibody-treated PC3 cells showed long membrane tethers. The probability density plots thus revealed that β1-integrin-specific interactions are predominately anchored to the cytoskeleton, while the nonspecific interactions are mainly membrane-anchored. Experiments with latrunculin-A-treated PC3 cells corroborated these observations. The plots thus reveal details of the anchoring of bonds to the cell and provide a better understanding of receptor-ligand interactions. PMID:26445433

  2. Stone anchors of India: Findings, classification and significance.

    Digital Repository Service at National Institute of Oceanography (India)

    Tripati, S.

    Virdi, Kodinar); Maharashtra (Dabhol, Vijaydurg, Sindhudurg); Goa (Baga, Grande Island, Sunchi Reef); Kerala (Kannur); Lakshadweep (Minicoy Island); Tamil Nadu (Gulf of Mannar, Tuticorin and Fig. 1 Map showing the stone anchor sites in India. (Sila...-Arabian type from Grande Island (Fig. 3f) and a pyramidal type of stone anchor from Baga waters (Sila Tripati et al., 2013). At first glance, the Baga stone anchor appears like an Indo-Arabian type (Fig. 3g). All these anchors of Goa are chance finds...

  3. Calculation of prestressed anchor segment by 3D infiniteelement

    Institute of Scientific and Technical Information of China (English)

    Yanfen WANG; Hongyang XIE; Yuanhan WANG

    2009-01-01

    Based on 1D infinite element theory, the coordinate transformation and shape function of 3D point-radiation 4-node infinite elements were derived.They were coupled with 8-node finite elements to compute the compressive deformation of the prestressed anchor segment. The results indicate that when the prestressed force acts on the anchor segment, the stresses and displacements in the rock around the anchor segment are concentrated in the zone center with the anchor axis and are subjected to exponential decay. Therefore, the stresses and the displacement spindles are formed. The calculation results of the infinite element are close to the theoretical results.

  4. AUV Load Separation Motion with Constraint of Anchor Chain

    Institute of Scientific and Technical Information of China (English)

    SHAO Cheng; SONG Bao-wei; DU Xiao-xu; WANG Peng; LI Jia-wang

    2009-01-01

    Motion equations of AUV(autonomous underwater vehicle) load separation with the constraint of anchor chain is derived. Based on proper engineering assumptions for anchor chain,system viewpoint is used to found the motion equations, and the D'Alembert principle is used to eliminate the constraint force of anchor chain. Based on the equations, the motion simulation is carried out to a certain AUV, which reflects the actual condition, and is used for the reference of resrarching AUV load separation motion with the constraint of anchor chain.

  5. Moody experts --- How mood and expertise influence judgmental anchoring

    Directory of Open Access Journals (Sweden)

    Birte Englich

    2009-02-01

    Full Text Available Anchoring effects, the assimilation of numerical estimates to previously considered standards, are highly robust. Two studies examined whether mood and expertise jointly moderate the magnitude of anchoring. Previous research has demonstrated that happy mood induces judges to process information in a less thorough manner than sad mood, which means that happy judges tend to be more susceptible to unwanted influences. However, this may not be true for anchoring effects. Because anchoring results from an elaborate process of selective knowledge activation, more thorough processing should lead to more anchoring; as a result, sad judges should show stronger anchoring effects than happy judges and happy judges may even remain uninfluenced by the given anchors. Because information processing of experts may be relatively independent of their mood, however, mood may influence anchoring only in non-experts. Results of two studies on legal decision-making (Study 1 and numeric estimates (Study 2 are consistent with these expectations. These findings suggest that, at least for non-experts, positive mood may eliminate the otherwise robust anchoring effect.

  6. Anchor Fitted with Special Fin for Soil Reinforcement

    Directory of Open Access Journals (Sweden)

    Abdul Ghani A.N.

    2014-01-01

    Full Text Available In order to ensure that anchored soil retention systems are more stable and free from failure, suitable anchors are required. A new technique using anchors with fins were investigated, particularly for mechanically stabilized earth. An experimental laboratory investigation on the behaviour of anchors with fins by using various shapes, sizes, arrangements and lengths were presented. The main purpose of this study is to investigate the load-displacement relationship of pullout anchors with fins embedded in sand. A rectangular model tank with dimensions 0.6 m length, 0.5 m width and 0.3 m high was designed. Models of 15 types of anchors of different lengths (0.3 m, 0.4 m and 0.5 m with fins using different and various types of lengths, sizes and arrangements embedded in sand, were experimented with . The testing program included 45 tests embedded in dry sand. The experiment was conducted in a soil laboratory at a scale of 1:10. The fin was placed at the end of the anchor shaft that abuts the failing structure which prevents further movement. It was concluded that the size, shape and angle of the fin influenced the pullout capacity of the anchor. Finally, selected anchors were recommended based on their superior performance.

  7. Nanostructured Amphiphilic Star-Hyperbranched Block Copolymers for Drug Delivery.

    Science.gov (United States)

    Seleci, Muharrem; Seleci, Didem Ag; Ciftci, Mustafa; Demirkol, Dilek Odaci; Stahl, Frank; Timur, Suna; Scheper, Thomas; Yagci, Yusuf

    2015-04-21

    A robust drug delivery system based on nanosized amphiphilic star-hyperbranched block copolymer, namely, poly(methyl methacrylate-block-poly(hydroxylethyl methacrylate) (PMMA-b-PHEMA) is described. PMMA-b-PHEMA was prepared by sequential visible light induced self-condensing vinyl polymerization (SCVP) and conventional vinyl polymerization. All of the synthesis and characterization details of the conjugates are reported. To accomplish tumor cell targeting property, initially cell-targeting (arginylglycylaspactic acid; RGD) and penetrating peptides (Cys-TAT) were binding to each other via the well-known EDC/NHS chemistry. Then, the resulting peptide was further incorporated to the surface of the amphiphilic hyperbranched copolymer via a coupling reaction between the thiol (-SH) group of the peptide and the hydroxyl group of copolymer by using N-(p-maleinimidophenyl) isocyanate as a heterolinker. The drug release property and targeting effect of the anticancer drug (doxorobucin; DOX) loaded nanostructures to two different cell lines were evaluated in vitro. U87 and MCF-7 were chosen as integrin αvβ3 receptor positive and negative cells for the comparison of the targeting efficiency, respectively. The data showed that drug-loaded copolymers exhibited enhanced cell inhibition toward U87 cells in compared to MCF-7 cells because targeting increased the cytotoxicity of drug-loaded copolymers against integrin αvβ3 receptor expressing tumor cells. PMID:25816726

  8. Preparation and Properties of Vesicles from Condensable Amphiphilic Amino Acids

    Institute of Scientific and Technical Information of China (English)

    熊向源; 何巍; 李子臣; 李福绵

    2001-01-01

    Three double-chain amphiphiles with amino acid groups as hydrphilic moiety were synthesized. These amphiphiles can be easily dispersed in buffer solution to form transparent dispersion. Examination of the dispersion by transmission electron microscopy (TEM) showed the formation of stable vesicular aggregates, which was also confirmed by the ability to encapsulate water-soluble dyes. Since amino acid groups are located on the surface of the vesicles, water-soluble carbodiimide can induce the condensation of these groups to form peptide. The phase transition temperatures of these vesicles were estimated by differential scanning calorimetry (DSC), and a decrease of phase transition temperature was observed after polycondensation due to the disturbance of the ordered arrangement of the hydrophobic chains. The leakage rate of the vesicles before and after condensation was studied by monitoring the increase of fluorescence intensity of water-soluble dye. These vesicles belong to the least permeable ones and the leakage rate can be controlled by varying the degree of condensation or the temperature.

  9. DEFORMATION OF COPOLYMER MICELLES INDUCED BY AMPHIPHILIC DIMER PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Xiao-chun Qin; Chun-lai Ren

    2012-01-01

    Combining self-consistent-field theory and density-functional theory,we systematically study the deformation of copolymer micelles induced by the presence of amphiphilic dimer particles.Due to the amphiphilic nature,dimer particles tend to accumulate onto the interface of the copolymer micelle.With increasing concentration of the symmetric dimer particles,which are made of two identical spherical particles,the micelle deforms from the initial sphere to ellipse,dumbbell,and finally separates into two micelles.Furthermore,asymmetric dimer particles,composed by two particles with different sizes,are considered to investigate the influence of geometry of dimer particles on the deformation of the micelle.It is found that the micelle inclines to deform into dumbbell due to the additional curvature originating in the gathering of asymmetric dimer particles onto the interface of the micelle.The present study on the deformation of micelles is useful to understand the possible shape variation in the course of cell division/fusion.

  10. Lipophosphoramidate-based bipolar amphiphiles: their syntheses and transfection properties.

    Science.gov (United States)

    Berchel, Mathieu; Le Gall, Tony; Lozach, Olivier; Haelters, Jean-Pierre; Montier, Tristan; Jaffrès, Paul-Alain

    2016-03-14

    Six new cationic bolaamphiphiles (also called bipolar amphiphiles, bolaform amphiphiles, or bolalipids) were readily prepared by a thiol-ene click reaction that engaged a mercapto-alcohol (mercapto-ethanol or mercapto-hexanol) and a cationic based lipophosphoramidate. The cationic lipophosphoramidates contain two lipid chains that end in an alkene group and a selected cationic polar head group (trimethylammonium, dimethyl hydroxyethyl ammonium, or methylimidazolium). These compounds were formulated in water (with or without DOPE as a colipid) to produce supramolecular aggregates. These aggregates, before (i.e. bolasomes) and after (i.e. bolaplexes) mixing with plasmid DNA (pDNA) at various charge ratios, were characterized with regard to their sizes and zeta potentials. In the case of bolasomes, the suspensions were unstable since precipitation occurred after only a few hours at room temperature. On the other hand, bolaplex formulations exhibited clearly a better colloidal stability. Then, the gene delivery properties of the cationic bolasomes were investigated using two human-derived epithelial cell lines (A549 and 16HBE). Compared to the commercially available lipofection reagent (Lipofectamine), most of the cationic bolaamphiphiles were able to efficiently transfect these cells when they were formulated with DOPE in a 1 : 1 molar ratio. We report herein that bolaamphiphiles possessing a trimethylammonium or a dimethyl hydroxyethyl ammonium head group were the most efficient in terms of transfection efficiency while exhibiting no significant cytotoxicity. PMID:26864681

  11. Synthesis and evaluation of amphiphilic peptides as nanostructures and drug delivery tools

    Science.gov (United States)

    Sayeh, Naser Ali

    Intracellular delivery of cell-impermeable compounds in a variety cells using delivery systems have been extensively studied in recent years. Obtaining desirable cellular uptake levels often requires the administration of high quantities of drugs to achieve the expected intracellular biological effect. Thus, improving the translocation process across the plasma membrane will significantly reduce the quantity of required administered drug and consequently minimize the side effects in most of the cases. Efficient delivery of these molecules to the cells and tissues is a difficult challenge. Compounds with low cellular permeability are commonly considered to be of limited therapeutic value. Over the past few decades, several biomedical carriers, such as polymers, nanospheres, nanocapsules, liposomes, micelles, peptides and dendrimers have been widely used to deliver therapeutic and diagnostic agents to the cells. Biomaterials generated from nano-scale compounds have shown some promising data for delivery of many compounds in a number of diseases, such as viral infections, cancer, and genetic disorders. Although much progress has been achieved in this field, many challenges still remain, such as toxicity and limited stability. Liposomes suffer from poor stability in the bloodstream and leakage during storage. They tend to aggregate and fuse with or leak entrapped drugs, especially highly hydrophilic small molecules. For solid lipid nanoparticles (SLNs), drug expulsion after polymorphic transition during storage, inadequate loading capacity, and relatively high water content of the dispersions have been observed. Poly(lactic-coglycolic acid (PLGA) degrades in the body producing its original monomers of lactic acid and glycolic acid, which are the by-products of various metabolic pathways. However, this acidic microenvironment that occurs during degradation could negatively affect the stability of the loaded compound. Dendrimers can carry drugs as complexes or as

  12. Translocation of a stiff polymer in a microchannel

    OpenAIRE

    Ten Bosch, Alexandra; Cheyssac, Pierre

    2009-01-01

    International audience The voltage-driven dynamics of a stiff polymer through a nanopore are treated with a bend elastic model. In contrast to flexible polymers described by a stretch elasticity, bend elastic chains can be oriented in an external field, here the anchoring field created by the pore atoms. The trajectory of the chain is calculated using the Langevin equation of motion. The dynamical equation is solved by a normal mode analysis of the elastic curve with free ends. Interaction...

  13. The Behavior of Amphiphile at Oil-Water Interface by Monte Carlo Simulation%双亲分子在油水界面的行为研究

    Institute of Scientific and Technical Information of China (English)

    潘海华; 李啸风; 李浩然; 刘迪霞; 韩世钧

    2003-01-01

    A novel simple two-dimensional square-lattice model of amphiphile at oil-water interface is developed,in which oil and water act as solvent and occupy empty sites and amphiphile occupies chains of sites. In thismodel, the oil-water interface is fixed, And amphiphile molecules will be enriched at the oil-water interface. Theinterfacial concentration of amphiphile calculated by Monte Carlo method shows that it is easier for the hydrophilic-hydrophobic balanced amphiphile to stay at the interface. And the adsorption of amphiphile increases with theincrease of amphiphile concentration and the decrease with temperature.

  14. Laser Propagation in Biaxial Liquid Crystal Polymers

    OpenAIRE

    Choate, Eric P.; Zhou, Hong

    2011-01-01

    We examine the propagation of a laser beam through a liquid crystal polymer (LCP) layer using the finite-difference time-domain (FDTD) method. Anchoring conditions on supporting glass plates induce an orientational structure in the LCP between the plates. The orientation can deflect energy away from the direction of propagation of the incident beam when the optical axis or major director of a uniaxial medium is neither parallel nor orthogonal to the incident beam. The maximum e...

  15. Self-assembly behavior of amphiphilic C₆₀-end-capped poly(vinyl ether)s in water and dissociation of the aggregates by the complexing of the C₆₀ moieties with externally added γ-cyclodextrins.

    Science.gov (United States)

    Motoyanagi, Jin; Kurata, Akihiro; Minoda, Masahiko

    2015-03-01

    C60-end-capped polymers consisting of an amphiphilic poly(2-methoxyethyl vinyl ether) (PMOVE) main chain were synthesized by living cationic polymerization using a C60-functionalized initiator (C60VE-TFA) in the presence of EtAlCl2 as an activator and dioxane as an added base. The obtained polymers (C60-PMOVE) dissolved in a wide range of solvents including water and exhibited solvatochromism depending on the polarity of the media employed. This phenomenon was attributed to self-assembly in polar media due to hydrophobicity of the C60 moieties at the terminus of the amphiphilic polymer chain. Furthermore, the addition of γ-cyclodextrin (γ-CD), a strong host molecule for fullerenes, to the self-assembled system brought about the dissociation of the aggregates into molecularly dispersed free polymer chains. Titration of the aqueous solution of the self-assembly of C60-PMOVE with γ-CD indicated the possible formation of inclusion complexes of C60-PMOVE and γ-CD, and this binding process occurs in a positive cooperative manner. PMID:25658224

  16. Multifunctional Composites Obtained by Incorporating Nanocrystals into Decorated PVK Polymers

    Directory of Open Access Journals (Sweden)

    Haizhu Sun

    2007-01-01

    Full Text Available Poly(vinylcarbazole (PVK was decorated with surfactant group to achieve amphiphilic polymer with luminescent property. The composition and properties of the polymers were systematically investigated using FTIR, EA, TGA, UV-Vis, and PL characterizations. Different CdTe nanocrystals (NCs prepared in aqueous medium were directly transferred to organic phase using the PVK-based polymers. The quantum yield of NCs in the composites had been improved by 50% compared with their parent aqueous solution due to the short distance from carbazole moieties to NCs, which facilitated the Förster resonant energy transfer (FRET between them. Moreover, efficient electron transfer at the interface of NCs and polymers had been confirmed which also indicated the application in photovoltaic cell for such composites.

  17. Synthesis of Polymerizable Amphiphiles with Systematic Variation of Critical Packing Parameters

    Institute of Scientific and Technical Information of China (English)

    M. H. Li; W. L. Yang; J. Qian; C. C. Wang; S. K. Fu

    2005-01-01

    @@ 1Introduction An amphiphile is a molecule composed of hydrophilic part and hydrophobic part, which are incompatible and tend to separate from each other. The tendency of separation is often promoted by addition of water and sometimes also oil. Under balanced conditions the mixtures form macroscopically homogeneous phases, including isotropic solution phases and liquid crystalline phases. Correlation of the amphiphile structure with its preferred phases could be understood with a simple geometric model[1], which defines a dimensionless Critical Packing Parameter (CPP) to describe the relative bulkiness of the hydrophobic part and the hydrophilic part in an amphiphile. With CPP increasing from a small value to a high value the amphiphile changes from hydrophilic to hydrophobic, its preferred phase structure from direct structures via lamellar structure to reverse structures. This model provides a basis for the molecular design of amphiphiles. To immobilize the microstructure of the phases formed by amphiphiles is a challenge for current material chemists. Techniques of both inorganic polymerization[2] and organic polymerization[3] have been developed. With organic polymerization the molecular design of polymerizable amphiphiles is critical for the successful immobilization of the vulnerable precursor microstructures.

  18. Electron paramagnetic resonance study of amphiphiles partitioning behavior in desiccation-tolerant moss during dehydration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Desiccation tolerance is a crucial characteristic for desert moss surviving in arid regions. Desiccation procedure always induces amphiphiles transferring from the polar cytoplasm into lipid bodies. The behavior of amphiphiles transferring can contribute to the enhancement of desiccation tolerance and the reduction of plasma membrane integrity simultaneously. The effects of amphiphiles partitioning into the lipid phase during water loss has been studied for pollen and seeds using electron paramagnetic resonance (EPR) spectroscopy. However, desiccation-tolerant high plants occur among mosses, several angiosperms and higher plants seeds or pollens. They have different strategies for survival in dehydration and rehydration. A desiccation-tolerant moss Tortula desertorurn was used to investigate the behaviors of amphiphilic molecules during drying by spin label technology. There are small amount of amphiphilic probes partitioning into membrane during moss leaves dehydration, comparing with that in higher plants. Cytoplasm viscosity changed from 1.14 into glass state only dehydration less than 60 min. Moss leaves lost plasma membrane integrity slightly,from 0.115 to 0.237, occurred simultaneously with amphiphiles partition. The results showed the more advantages of mosses than higher plants in adapting fast dehydration. We propose that EPR spin label is feasible for studying the amphiphiles partitioning mechanisms in membrane protection and damage for desiccation-tolerant mosses.(C) 2007 Yan Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  19. Self-assembly of phosphate amphiphiles in mixtures of prebiotically plausible surfactants.

    Science.gov (United States)

    Albertsen, A N; Duffy, C D; Sutherland, J D; Monnard, P-A

    2014-06-01

    The spontaneous formation of closed bilayer structures from prebiotically plausible amphiphiles is an essential requirement for the emergence of early cells on prebiotic Earth. The sources of amphiphiles could have been both endo- and exogenous (accretion of meteorite carbonaceous material or interstellar dust particles). Among all prebiotic possible amphiphile candidates, those containing phosphate are the least investigated species because their self-assembly occurs in a seemingly too narrow range of conditions. The self-assembly of simple phosphate amphiphiles should, however, be of great interest, as contemporary membranes predominantly contain phospholipids. In contrast to common expectations, we show that these amphiphiles can be easily synthesized under prebiotically plausible environmental conditions and can efficiently form bilayer structures in the presence of various co-surfactants across a large range of pH values. Vesiculation was even observed in crude reaction mixtures that contained 1-decanol as the amphiphile precursor. The two best co-surfactants promoted vesicle formation over the entire pH range in aqueous solutions. Expanding the pH range where bilayer membranes self-assemble and remain intact is a prerequisite for the emergence of early cell-like compartments and their preservation under fluctuating environmental conditions. These mixed bilayers also retained small charged solutes, such as dyes. These results demonstrate that alkyl phosphate amphiphiles might have played a significant role as early compartment building blocks.

  20. Stable and robust nanotubes formed from self-assembled polymer membranes

    Science.gov (United States)

    Helmerson, Kristian; Reiner, Joseph E.; Kishore, Rani B.; Jofre, Ana; Allegrini, Maria; Pfefferkorn, Candace; Wells, Jeffrey M.

    2006-08-01

    We create long polymer nanotubes by directly pulling on the membrane of polymersomes using either optical tweezers or a micropipette. The polymersomes are composed of amphiphilic diblock copolymers and the nanotubes formed have an aqueous core connected to the aqueous interior of the polymersome. We stabilize the pulled nanotubes by subsequent chemical cross-linking. The cross-linked nanotubes are extremely robust and can be moved to another medium for use elsewhere. We demonstrate the ability to form networks of polymer nanotubes and polymersomes by optical manipulation. The aqueous core of the polymer nanotubes together with their robust character makes them interesting candidates for nanofluidics and other applications in biotechnology.

  1. Neutron reflectivity measurement of polymer monolayer and brush at the air/water interface

    International Nuclear Information System (INIS)

    We have been studied on amphiphilic polymer monolayer structure at the air/water interface by X-ray and neutron reflectometry. By complemently use of X-ray and neutron reflectometry, we have found (1) the existence of carpet layer in ionic polymer brush in monolayer system and (2) characteristic structural change in polymer/subphase interface. Furthermore, interesting experiment on small ion distribution was carried out by NR with contrast variation method. With our experimental examples, characteristic points in the neutron reflectivity measurement at the air/water interface and further possibility in this research area are discussed. (author)

  2. Novel polystyrene-anchored zinc complex:Efficient catalyst for phenol oxidation

    Institute of Scientific and Technical Information of China (English)

    Alekha Kumar Sutar a; Yasobanta Das ab; Sasmita Pattnaik a; Anita Routaray a; Nibedita Nath a; Prasanta Rath b; Tungabidya Maharana c

    2014-01-01

    The novel recyclable free -ONNO- tetradentate Schiff base ligand N,N′-bis(2-hydroxy-3-methox-ybenzaldehyde)4-methylbenzene-1,2-diamine (3-MOBdMBn) was synthesized. Complexation of this ligand with zinc (3-MOBdMBn-Zn) was performed, and the catalytic activity of the complex was evaluated. The polymer-supported analog of this complex (P-3-MOBdMBn-Zn) was synthesized, and its catalytic activity was studied. These free and polymer-anchored zinc complexes were prepared by the reactions of metal solutions with one molar equivalent of unsupported 3-MOBdMBn or P-3-MOBdMBn in methanol under nitrogen. The catalytic activity of 3-MOBdMBn-Zn and P-3-MOBdMBn-Zn was evaluated in phenol oxidation. The activity of P-3-MOBdMBn-Zn was signif-icantly affected by the polymer support, and the rate of phenol conversion was around 50%for polystyrene-supported 3-MOBdMBn. The experimental results indicated that the reaction rate was affected by the polymer support, and the rate of phenol conversion was 1.64 μmol/(L·s) in the presence of polystyrene-supported 3-MOBdMBn.

  3. Amphiphilic copolymers based on polyoxazoline and grape seed vegetable oil derivatives: self-assemblies and dynamic light scattering

    International Nuclear Information System (INIS)

    The self-assembly in solution of original structures of amphiphilic partially natural copolymers based on polyoxazoline [more precisely poly(2-methyl-2-oxazoline) (POx)] and grape seed vegetable oil derivatives (linear, T-, and trident-structure) is investigated. The results show that such systems are found, using dynamic light scattering (DLS), to spontaneously self-organize into monomodal, narrow-size, and stable nanoparticles in aqueous medium. The obtained hydrodynamic diameters (Dh) range from 8.6 to 32.5 nm. Specifically, such size increases strongly with increasing natural block (i.e., lipophilic species) length due to higher hydrophobic interactions (from 10.1 nm for C19 to 19.2 nm for C57). Furthermore, increasing the polyoxazoline (i.e., hydrophilic block) length leads to a moderate linear increase of the Dh-values. Therefore, the first-order size effect comes from the natural lipophilic block, whereas the characteristic size can be tuned more finely (i.e., in a second-order) by choosing appropriately the polyoxazoline length. The DLS results in terms of characteristic size are corroborated using nanoparticle tracking analysis (NTA), and also by atomic force microscopy (AFM) and transmission electron microscopy (TEM) imaging where well-defined spherical and individual nanoparticles exhibit a very good mechanical resistance upon drying. Moreover, changing the lipophilic block architecture from linear to T-shape, while keeping the same molar mass, generates a branching and thus a shrinking by a factor of 2 of the nanoparticle volume, as observed by DLS. In this paper, it is clearly shown that the self-assemblies of amphiphilic block copolymer obtained from grape seed vegetable oil derivatives (sustainable renewable resources) as well as their tunability are of great interest for biomass valorization at the nanoscale level [continuation of the article by Stemmelen et al. (Polym Chem 4:1445–1458, 2013)].Graphical AbstractAmphiphilic copolymers based on

  4. Amphiphilic copolymers based on polyoxazoline and grape seed vegetable oil derivatives: self-assemblies and dynamic light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Travelet, Christophe, E-mail: Christophe.Travelet@cermav.cnrs.fr [Universite Joseph Fourier (UJF), Institut de Chimie Moleculaire de Grenoble (ICMG-FR 2607 CNRS), PolyNat Carnot institute, Arcane LabEx, domaine universitaire de Grenoble, Centre de Recherches sur les Macromolecules Vegetales - CERMAV-UPR 5301 CNRS (France); Stemmelen, Mylene; Lapinte, Vincent [Universite de Montpellier II, Institut Charles Gerhardt Montpellier (UMR 5253 CNRS-UM2-UM1-ENSCM), equipe ingenierie et architectures macromoleculaires (France); Dubreuil, Frederic [Universite Joseph Fourier (UJF), Institut de Chimie Moleculaire de Grenoble (ICMG-FR 2607 CNRS), PolyNat Carnot institute, Arcane LabEx, domaine universitaire de Grenoble, Centre de Recherches sur les Macromolecules Vegetales - CERMAV-UPR 5301 CNRS (France); Robin, Jean-Jacques [Universite de Montpellier II, Institut Charles Gerhardt Montpellier (UMR 5253 CNRS-UM2-UM1-ENSCM), equipe ingenierie et architectures macromoleculaires (France); and others

    2013-06-15

    The self-assembly in solution of original structures of amphiphilic partially natural copolymers based on polyoxazoline [more precisely poly(2-methyl-2-oxazoline) (POx)] and grape seed vegetable oil derivatives (linear, T-, and trident-structure) is investigated. The results show that such systems are found, using dynamic light scattering (DLS), to spontaneously self-organize into monomodal, narrow-size, and stable nanoparticles in aqueous medium. The obtained hydrodynamic diameters (D{sub h}) range from 8.6 to 32.5 nm. Specifically, such size increases strongly with increasing natural block (i.e., lipophilic species) length due to higher hydrophobic interactions (from 10.1 nm for C{sub 19} to 19.2 nm for C{sub 57}). Furthermore, increasing the polyoxazoline (i.e., hydrophilic block) length leads to a moderate linear increase of the D{sub h}-values. Therefore, the first-order size effect comes from the natural lipophilic block, whereas the characteristic size can be tuned more finely (i.e., in a second-order) by choosing appropriately the polyoxazoline length. The DLS results in terms of characteristic size are corroborated using nanoparticle tracking analysis (NTA), and also by atomic force microscopy (AFM) and transmission electron microscopy (TEM) imaging where well-defined spherical and individual nanoparticles exhibit a very good mechanical resistance upon drying. Moreover, changing the lipophilic block architecture from linear to T-shape, while keeping the same molar mass, generates a branching and thus a shrinking by a factor of 2 of the nanoparticle volume, as observed by DLS. In this paper, it is clearly shown that the self-assemblies of amphiphilic block copolymer obtained from grape seed vegetable oil derivatives (sustainable renewable resources) as well as their tunability are of great interest for biomass valorization at the nanoscale level [continuation of the article by Stemmelen et al. (Polym Chem 4:1445-1458, 2013)].Graphical AbstractAmphiphilic

  5. Degradable copolymer based on amphiphilic N-octyl-N-quatenary chitosan and low-molecular weight polyethylenimine for gene delivery

    Directory of Open Access Journals (Sweden)

    Liu CC

    2012-10-01

    Full Text Available Chengchu Liu,1,2,* Qing Zhu,1,* Wenhui Wu,1 Xiaolin Xu,1 Xiaoyu Wang,3 Shen Gao,3 Kehai Liu11Department of Biopharmaceutics, College of Food Science and Technology, Shanghai Ocean University, Shanghai, China; 2Shanghai Engineering Research Center of Aquatic-Product Processing and Preservation, Shanghai, China; 3Department of Pharmaceutics, Changhai Hospital, Second Military Medical University, Shanghai China*The first two authors contributed equally to this workBackground: Chitosan shows particularly high biocompatibility and fairly low cytotoxicity. However, chitosan is insoluble at physiological pH. Moreover, it lacks charge, so shows poor transfection. In order to develop a new type of gene vector with high transfection efficiency and low cytotoxicity, amphiphilic chitosan was synthesized and linked with low-molecular weight polyethylenimine (PEI.Methods: We first synthesized amphiphilic chitosan – N-octyl-N-quatenary chitosan (OTMCS, then prepared degradable PEI derivates by cross-linking low-molecular weight PEI with amphiphilic chitosan to produce a new polymeric gene vector (OTMCS–PEI. The new gene vector was characterized by various physicochemical methods. We also determined its cytotoxicity and gene transfecton efficiency in vitro and in vivo.Results: The vector showed controlled degradation. It was very stable and showed excellent buffering capacity. The particle sizes of the OTMCS–PEI/DNA complexes were around 150–200 nm with proper zeta potentials from 10 mV to 30 mV. The polymer could protect plasmid DNA from being digested by DNase I at a concentration of 2.25 U DNase I/µg DNA. Furthermore, they were resistant to dissociation induced by 50% fetal bovine serum and 1100 µg/mL sodium heparin. OTMCS–PEI revealed lower cytotoxicity, even at higher doses. Compared with PEI 25 KDa, the OTMCS–PEI/DNA complexes also showed higher transfection efficiency in vitro and in vivo.Conclusion: OTMCS–PEI was a potential candidate as

  6. 30 CFR 57.9311 - Anchoring stationary sizing devices.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Anchoring stationary sizing devices. 57.9311 Section 57.9311 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Dumping Sites § 57.9311 Anchoring stationary sizing devices. Grizzlies and other stationary sizing...

  7. 30 CFR 56.9311 - Anchoring stationary sizing devices.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Anchoring stationary sizing devices. 56.9311 Section 56.9311 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Dumping Sites § 56.9311 Anchoring stationary sizing devices. Grizzlies and other stationary sizing...

  8. Understanding Rasch Measurement: Partial Credit Model and Pivot Anchoring.

    Science.gov (United States)

    Bode, Rita K.

    2001-01-01

    Describes the Rasch measurement partial credit model, what it is, how it differs from other Rasch models, and when and how to use it. Also describes the calibration of instruments with increasingly complex items. Explains pivot anchoring and illustrates its use and describes the effect of pivot anchoring on step calibrations, item hierarchy, and…

  9. Proteomic analysis of GPI-anchored membrane proteins

    DEFF Research Database (Denmark)

    Jung, Hye Ryung; Jensen, Ole Nørregaard

    2006-01-01

    Glycosyl-phosphatidyl-inositol-anchored proteins (GPI-APs) represent a subset of post-translationally modified proteins that are tethered to the outer leaflet of the plasma membrane via a C-terminal GPI anchor. GPI-APs are found in a variety of eukaryote species, from pathogenic microorganisms...

  10. Cucurbit[7]uriI-Based Vesicles Formed by Self-assembly of Supramolecular Amphiphiles

    Institute of Scientific and Technical Information of China (English)

    李佳锡; 周黎鹏; 罗全; 王永国; 张春秋; 卢伟; 徐家云; 刘俊秋

    2012-01-01

    Cucurbituril (CB), a well-known macrocyclic cavitand, has been used extensively to construct supramolecular aggregates. Based on host-guest intertactions, an adamantanyl derivative guest molecule was designed and syn- thesized to prepare a supramolecular amphiphile with cucurbit[7]uril. In aqueous solution, the cucurbit[7]uril based supramolecular amphiphiles self-assemble into well-defined vesicles, and their disassembly can be achieved by addition of excess competitive agent 1-adamantanamine hydrochloride. This vesicle functions as a new nanocapsule to encapsulate molecules within its hollow cavity. Through competitive disassembly of supramolecular amphiphiles, the vesicles behave as a novel drug delivery carrier.

  11. Syntheses, Characterization, Physical and Biological Properties of Long-chain, Water-soluble, Dendritic Amphiphiles

    OpenAIRE

    Williams, André Arvin

    2008-01-01

    In this project, we have designed and synthesized a new series of long-chain, water-soluble, dendritic, anionic amphiphiles [3CAmn, RCONHC(CH2CH2COOH)3, R= CnH2n+1] to alleviate the low aqueous solubility of fatty acids. The dendritic-tricarboxlyato headgroup improves aqueous solubility and allows us to measure the intrinsic biological activity of our amphiphiles without the potential hindrance of low aqueous solubility. The aqueous solubilities of the anionic amphiphiles have been measured...

  12. Where surface physics and fluid dynamics meet: rupture of an amphiphile layer by fluid flow

    OpenAIRE

    Bandi, Mahesh; Goldburg, Walter; Cressman Jr., John; Kellay, Hamid

    2006-01-01

    We investigate the fluctuating pattern created by a jet of fluid impingent upon an amphiphile-covered surface. This microscopically thin layer is initially covered with 50 $\\mu$m floating particles so that the layer can be visualized. A vertical jet of water located below the surface and directed upward drives a hole in this layer. The hole is particle-free and is surrounded by the particle-laden amphiphile region. The jet ruptures the amphiphile layer creating a particle-free region that is ...

  13. Electrically insulated MLI and thermal anchor

    Science.gov (United States)

    Kamiya, Koji; Furukawa, Masato; Hatakenaka, Ryuta; Miyakita, Takeshi; Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Koidea, Yoshihiko; Yoshida, Kiyoshi

    2014-01-01

    The thermal shield of JT-60SA is kept at 80 K and will use the multilayer insulation (MLI) to reduce radiation heat load to the superconducting coils at 4.4 K from the cryostat at 300 K. Due to plasma pulse operation, the MLI is affected by eddy current in toroidal direction. The MLI is designed to suppress the current by electrically insulating every 20 degree in the toroidal direction by covering the MLI with polyimide films. In this paper, two kinds of designs for the MLI system are proposed, focusing on a way to overlap the layers. A boil-off calorimeter method and temperature measurement has been performed to determine the thermal performance of the MLI system. The design of the electrical insulated thermal anchor between the toroidal field (TF) coil and the thermal shield is also explained.

  14. Synthesis of polymer-biohybrids: from small to giant surfactants.

    Science.gov (United States)

    Reynhout, Irene C; Cornelissen, Jeroen J L M; Nolte, Roeland J M

    2009-06-16

    Amphiphiles or surfactants, more popularly known as soaps, are among the oldest known chemical compounds used by man. Written text on a clay tablet dated to 2200 B.C. indicates that the Babylonians were familiar with soap-like substances. According to the Ebers papyrus (1550 B.C.), the ancient Egyptians bathed regularly in a mixture of animal oils, vegetable extracts, and alkaline salts, and a soap factory with bars of scented soap was found in the ruins of Pompeii (79 A.D.). In modern times, the use of soap has become universal, and we now understand reasonably well what happens when soap molecules are dispersed in aqueous solution and how the cleaning properties of soap work. The latter is related to the surface-active behavior of soap molecules, which is a result of their amphiphilic, also called amphipathic, character. Although the cleaning aspect is still an important issue, scientists are increasingly focusing on other properties of soaps, for example, self-assembling behavior and how this can be used in the design and non-covalent synthesis of new (macro)molecular architectures. These new molecules can be employed in nanotechnology and drug delivery, among other applications. This Account will focus on three different classes of amphiphiles. The first is the low molecular weight amphiphiles, also called classical amphiphiles in this context. A short overview will be given on the research carried out by our group and others on the self-assembly behavior and properties of these compounds; in particular, we focus on the ones that can be stabilized by polymerization (polymerized vesicles). Next, we will introduce the still relatively young field of superamphiphiles, macromolecules consisting of a hydrophobic and a hydrophilic polymeric block. Finally, and this constitutes the main part of this Account, we will provide an overview of a new class of amphiphiles, the so-called giant amphiphiles. These macromolecules have an enzyme or protein as the polar head group

  15. Synthesis of polymer-biohybrids: from small to giant surfactants.

    Science.gov (United States)

    Reynhout, Irene C; Cornelissen, Jeroen J L M; Nolte, Roeland J M

    2009-06-16

    Amphiphiles or surfactants, more popularly known as soaps, are among the oldest known chemical compounds used by man. Written text on a clay tablet dated to 2200 B.C. indicates that the Babylonians were familiar with soap-like substances. According to the Ebers papyrus (1550 B.C.), the ancient Egyptians bathed regularly in a mixture of animal oils, vegetable extracts, and alkaline salts, and a soap factory with bars of scented soap was found in the ruins of Pompeii (79 A.D.). In modern times, the use of soap has become universal, and we now understand reasonably well what happens when soap molecules are dispersed in aqueous solution and how the cleaning properties of soap work. The latter is related to the surface-active behavior of soap molecules, which is a result of their amphiphilic, also called amphipathic, character. Although the cleaning aspect is still an important issue, scientists are increasingly focusing on other properties of soaps, for example, self-assembling behavior and how this can be used in the design and non-covalent synthesis of new (macro)molecular architectures. These new molecules can be employed in nanotechnology and drug delivery, among other applications. This Account will focus on three different classes of amphiphiles. The first is the low molecular weight amphiphiles, also called classical amphiphiles in this context. A short overview will be given on the research carried out by our group and others on the self-assembly behavior and properties of these compounds; in particular, we focus on the ones that can be stabilized by polymerization (polymerized vesicles). Next, we will introduce the still relatively young field of superamphiphiles, macromolecules consisting of a hydrophobic and a hydrophilic polymeric block. Finally, and this constitutes the main part of this Account, we will provide an overview of a new class of amphiphiles, the so-called giant amphiphiles. These macromolecules have an enzyme or protein as the polar head group

  16. Anchoring submersible ultrasonic receivers in river channels with stable substrate

    Science.gov (United States)

    Bettoli, Phillip William; Scholten, G.D.; Hubbs, D.

    2010-01-01

    We developed an anchoring system for submersible ultrasonic receivers (SURs) that we placed on the bottom of the riverine reaches of three main-stem reservoirs in the upper Tennessee River. Each anchor consisted of a steel tube (8.9 x 35.6 cm) welded vertically to a round plate of steel (5.1 x 40.6 cm). All seven SURs and their 57-kg anchors were successfully deployed and retrieved three times over 547 d by a dive team employing surface air-breathing equipment and a davit-equipped boat. All of the anchors and their SURs remained stationary over two consecutive winters on the hard-bottom, thalweg sites where they were deployed. The SUR and its anchor at the most downriver site experienced flows that exceeded 2,100 m(3)/s and mean water column velocities of about 0.9 m/s.

  17. Grapnel stone anchors from Saurashtra: Remnants of Indo-Arab trade on the Indian coast

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Sundaresh; Tripati, S.

    Stone anchors have been used as a primary source of information on ancient navigation by marine archaeologists since long. These anchors used by ancient mariners are often noticed underwater at various places across the world. Stone anchors are also...

  18. Pyramidal anchor stone from Baga waters of Goa, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Tripati, S.

    Underwater exploration in the coastal region off Baga (Goa, India) led to the recovery of an isolated stone artefact, which resembles a pyramidal type of anchor stone. This anchor stone is unlike to other pyramidal anchor stones found elsewhere...

  19. Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor

    OpenAIRE

    Rajesh Munirathinam; Roberto Ricciardi; Egberink, Richard J.M.; Jurriaan Huskens; Michael Holtkamp; Herbert Wormeester; Uwe Karst; Willem Verboom

    2013-01-01

    Polystyrene sulfonate polymer brushes, grown on the interior of the microchannels in a microreactor, have been used for the anchoring of gallium as a Lewis acid catalyst. Initially, gallium-containing polymer brushes were grown on a flat silicon oxide surface and were characterized by FTIR, ellipsometry, and X-ray photoelectron spectroscopy (XPS). XPS revealed the presence of one gallium per 2–3 styrene sulfonate groups of the polymer brushes. The catalytic activity of the Lewis acid-function...

  20. The Use of Two Anchors in Nonequivalent Groups with Anchor Test (NEAT) Equating. Research Report. ETS RR-10-23

    Science.gov (United States)

    Moses, Tim; Deng, Weiling; Zhang, Yu-Li

    2010-01-01

    In the equating literature, a recurring concern is that equating functions that utilize a single anchor to account for examinee groups' nonequivalence are biased when the groups are extremely different and/or when the anchor only weakly measures what the tests measure. Several proposals have been made to address this equating bias by incorporating…

  1. Formation of nanoscale networks: selectively swelling amphiphilic block copolymers with CO2-expanded liquids

    Science.gov (United States)

    Gong, Jianliang; Zhang, Aijuan; Bai, Hua; Zhang, Qingkun; Du, Can; Li, Lei; Hong, Yanzhen; Li, Jun

    2013-01-01

    Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO2-expanded liquid (CXL), CO2-methanol. The phase behavior of the CO2-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO2, forming homogeneous CXL under the experimental conditions. When treated with the CO2-methanol system, the spin cast compact PS-b-P4VP film was transformed into a network with interconnected pores, in a pressure range of 12-20 MPa and a temperature range of 45-60 °C. The formation mechanism of the network, involving plasticization of PS and selective swelling of P4VP, was proposed. Because the diblock copolymer diffusion process is controlled by the activated hopping of individual block copolymer chains with the thermodynamic barrier for moving PVP segments from one to another, the formation of the network structures is achieved in a short time scale and shows ``thermodynamically restricted'' character. Furthermore, the resulting polymer networks were employed as templates, for the preparation of polypyrrole networks, by an electrochemical polymerization process. The prepared porous polypyrrole film was used to fabricate a chemoresistor-type gas sensor which showed high sensitivity towards ammonia.Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO2-expanded liquid (CXL), CO2-methanol. The phase behavior of the CO2-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO2, forming homogeneous CXL under the experimental conditions. When treated with the CO2-methanol system, the spin cast compact PS-b-P4VP film was transformed into a network with interconnected pores, in a pressure range of 12-20 MPa and a

  2. Bulk modification of PDMS microchips by an amphiphilic copolymer.

    Science.gov (United States)

    Xiao, Yan; Yu, Xiao-Dong; Xu, Jing-Juan; Chen, Hong-Yuan

    2007-09-01

    A simple and rapid bulk-modification method based on adding an amphiphilic copolymer during the fabrication process was employed to modify PDMS microchips. Poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) was used as the additive substance. Compared to the native PDMS microchips, both the contact angle and the EOF of the bulk-modified PDMS microchips decreased. The effects of the additive loading and the pH on the EOF were investigated in detail. The bulk-modified PDMS microchips exhibited reproducible and stable EOF behavior. The application of the bulk-modified PDMS microchips was also studied and the results indicated that they could be successfully used to separate amino acids and to suppress protein adsorption.

  3. [Study of novel artificial lung surfactants incorporating partially fluorinated amphiphiles].

    Science.gov (United States)

    Nakahara, Hiromichi

    2012-01-01

    Lung surfactants (LS), a complex of ∼90 wt% lipids (mainly dipalmitoylphosphatidylcholine or DPPC) and ∼10 wt% surfactant proteins (SP-A, -B, -C, and -D), adsorb to an air-alveolar fluid interface and then lower its surface tension down to near zero during expiration. Intratracheal instillation of exogenous LS preparations can effectively compensate for surfactant deficiency in premature infants with respiratory distress syndrome (RDS). Surfacten® (Mitsubishi Tanabe Pharma Corporation, Osaka, Japan), a modified bovine lung extract and an effective surfactant replacement in treatment for RDS patients, is supplemented with DPPC, palmitic acid, and tripalmitin. For the premature infants suffering from RDS, instillation of Surfacten® leads to a dramatic improvement in lung function and compliance. Herein, the author reviews potential use of newly designed preparations containing a mimicking peptide of SP-B and also introduces the current research on the preparations incorporated with partially fluorinated amphiphiles to improve their efficacy. PMID:22790027

  4. Supramolecular chirality in self-assembled peptide amphiphile nanostructures.

    Science.gov (United States)

    Garifullin, Ruslan; Guler, Mustafa O

    2015-08-11

    Induced supramolecular chirality was investigated in the self-assembled peptide amphiphile (PA) nanosystems. Having shown that peptide chirality can be transferred to the covalently-attached achiral pyrene moiety upon PA self-assembly, the chiral information is transferred to molecular pyrene via weak noncovalent interactions. In the first design of a supramolecular chiral system, the chromophore was covalently attached to a peptide sequence (VVAGH) via an ε-aminohexanoic acid spacer. Covalent attachment yielded a PA molecule self-assembling into nanofibers. In the second design, the chromophore was encapsulated within the hydrophobic core of self-assembled nanofibers of another PA consisting of the same peptide sequence attached to lauric acid. We observed that supramolecular chirality was induced in the chromophore by PA assembly into chiral nanostructures, whether it was covalently attached, or noncovalently bound. PMID:26146021

  5. Structure and reactivity in amphiphile-water micelles

    International Nuclear Information System (INIS)

    Following a review of the general properties of micelles, this report contains two parts: - A structural study of octylphosphate micelles. Important structural changes have been evidenced by mean of small angle neutron scattering as the electrical charge of the interface is varied. The NMR relaxation study of the conformation of the hydrocarbon chains has shown that the micellar core is disordered in contrast with the interface which is rather structured. The diffusion motions in the interface and the segmental motions of the chains are fast. - Studies on the reactivity in micelles have been carried out. A large micellar effect on the complexation of transition ions by amphiphilic ligands is evidenced. The problem of solute localization in micelles is developed with few examples. (author)

  6. Amphiphilic siderophore production by oil-associating microbes.

    Science.gov (United States)

    Kem, Michelle P; Zane, Hannah K; Springer, Stephen D; Gauglitz, Julia M; Butler, Alison

    2014-06-01

    The Deepwater Horizon oil spill in 2010 released an unprecedented amount of oil into the ocean waters of the Gulf of Mexico. As a consequence, bioremediation by oil-degrading microbes has been a topic of increased focus. One factor limiting the rate of hydrocarbon degradation by microbial communities is the availability of necessary nutrients, including iron. The siderophores produced from two Vibrio spp. isolated from the Gulf of Mexico following the Deepwater Horizon oil spill, along with the well-studied oil-degrading microbe, Alcanivorax borkumensis SK2, are studied under iron-limiting conditions. Here we report the amphiphilic amphibactin siderophores produced by the oil-associated bacteria, Vibrio sp. S1B, Vibrio sp. S2A and Alcanivorax borkumensis SK2. These findings provide insight into oil-associating microbial iron acquisition. PMID:24663669

  7. Photoaddressable Polymers

    Science.gov (United States)

    Bieringer, T.

    Polymers are the perfect materials for a variety of applications in almost every field of technical as well as human life. Because of their macromolecular architecture there are a lot of degrees of freedom in the synthesis of polymers. Owing to the change of their functional composition, they can be tailored even for quite difficult demands. Since a whole industry deals with the processing of polymers, cheap production lines have been developed for almost every polymer. This is the reason why not only the molecular composition but even the price of polymers has been optimized. Therefore these materials can be considered as encouraging components even in highly sophisticated areas of applications.

  8. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    Directory of Open Access Journals (Sweden)

    Sanjib K. Shrestha

    2014-12-01

    Full Text Available K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20’s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were determined. Effects on Cryptococcus neoformans H-99 infectivity were determined with a preventive murine lung infection model. The antifungal mechanism of action was studied using intact fungal cells, yeast lipid mutants, and small unilamellar lipid vesicles. K20 exhibited broad-spectrum in vitro antifungal activities but not antibacterial activities. Pulmonary, single dose-administration of K20 reduced C. neoformans lung infection rates 4-fold compared to controls. Hemolysis and half-maximal cytotoxicities of mammalian cells occurred at concentrations that were 10 to 32-fold higher than fungicidal MICs. With fluorescein isothiocyanate, 20 to 25 mg/L K20 caused staining of >95% of C. neoformans and Fusarium graminearum cells and at 31.3 mg/L caused rapid leakage (30 to 80% in 15 min of calcein from preloaded small unilamellar lipid vesicles. K20 appears to be a broad-spectrum fungicide, capable of reducing the infectivity of C. neoformans, and exhibits low hemolytic activity and mammalian cell toxicity. It perturbs the plasma membrane by mechanisms that are lipid modulated. K20 is a novel amphiphilic aminoglycoside amenable to scalable production and a potential lead antifungal for therapeutic and crop protection applications.

  9. Globules of annealed amphiphilic copolymers: Surface structure and interactions

    Science.gov (United States)

    Jarkova, E.; Johner, A.; Maresov, E. A.; Semenov, A. N.

    2006-12-01

    A mean-field theory of globules of random amphiphilic copolymers in selective solvents is developed for the case of an annealed copolymer sequence: each unit can be in one of two states, H (insoluble) or P (soluble or less insoluble). The study is focussed on the regime when H and P units tend to form long blocks, and when P units dominate in the dilute phase, but are rare in the globule core. A first-order coil-to-globule transition is predicted at some T = Tcg. The globule core density at the transition point increases as the affinity of P units to the solvent, tildeɛ, is increased. Two collapse transitions, coil → “loose” globule and “loose” globule → “dense” globule, are predicted if tildeɛ is high enough and P units are marginally soluble or weakly insoluble. H and P concentration profiles near the globule surface are obtained and analyzed in detail. It is shown that the surface excess of P units rises as tildeɛ is increased. The surface tension decreases in parallel. Considering the interaction between close enough surfaces of two globules, we show that they always attract each other at a complete equilibrium. It is pointed out, however, that such equilibrium may be difficult to reach, so that partially equilibrium structures (defined by the condition that a chain forming one globule does not penetrate into the core of the other globule) are relevant. It is shown that at such partial equilibrium the interaction is repulsive, so the globules may be stabilized from aggregation. The strongest repulsion is predicted at the coil-to-globule transition point Tcg: the repulsion force decreases with the distance between the surfaces according to a power law. In the general case (apart from Tcg) the force vs. distance decay becomes exponential; the decay length ξ diverges as T → Tcg. The developed theory explains certain anomalous properties observed for globules of amphiphilic homopolymers.

  10. Effect of polymer matrix on structure of Se particles formed in aqueous solutions during redox process

    Energy Technology Data Exchange (ETDEWEB)

    Suvorova, E. I., E-mail: suvorova@ns.crys.ras.ru; Klechkovskaya, V. V. [Shubnikov Institute of Crystallography of Russian Academy of Sciences (Russian Federation)

    2010-12-15

    Transmission electron microscopy and X-ray energy dispersive microanalysis study of the structure of particles formed during the reduction of Se(IV) to Se(0) in aqueous solutions in the presence of amphiphilic polymers showed the formation of Se/polymer composite particles. The content of carbon inside the particles can be as large as 80 at %. Polymers deeply influence the structure of particles. Depending on polymers, the composite particles may be unstable with time and they spontaneously evolve from Se/polymer composite particles to crystalline particles of monoclinic Se. For the stable ones, addition of bacterial cellulose Acetobacter xylinum gel-film can induce crystallization in the particles which expel the polymeric material. The Se/polymer composite particles and Se crystalline particles exhibit different sensitivity to electron irradiation and stiffness.

  11. Amphiphilic macromolecule nanoassemblies suppress smooth muscle cell proliferation and platelet adhesion.

    Science.gov (United States)

    Chan, Jennifer W; Lewis, Daniel R; Petersen, Latrisha K; Moghe, Prabhas V; Uhrich, Kathryn E

    2016-04-01

    While the development of second- and third-generation drug-eluting stents (DES) have significantly improved patient outcomes by reducing smooth muscle cell (SMC) proliferation, DES have also been associated with an increased risk of late-stent thrombosis due to delayed re-endothelialization and hypersensitivity reactions from the drug-polymer coating. Furthermore, DES anti-proliferative agents do not counteract the upstream oxidative stress that triggers the SMC proliferation cascade. In this study, we investigate biocompatible amphiphilic macromolecules (AMs) that address high oxidative lipoprotein microenvironments by competitively binding oxidized lipid receptors and suppressing SMC proliferation with minimal cytotoxicity. To determine the influence of nanoscale assembly on proliferation, micelles and nanoparticles were fabricated from AM unimers containing a phosphonate or carboxylate end-group, a sugar-based hydrophobic domain, and a hydrophilic poly(ethylene glycol) domain. The results indicate that when SMCs are exposed to high levels of oxidized lipid stimuli, nanotherapeutics inhibit lipid uptake, downregulate scavenger receptor expression, and attenuate scavenger receptor gene transcription in SMCs, and thus significantly suppress proliferation. Although both functional end-groups were similarly efficacious, nanoparticles suppressed oxidized lipid uptake and scavenger receptor expression more effectively compared to micelles, indicating the relative importance of formulation characteristics (e.g., higher localized AM concentrations and nanotherapeutic stability) in scavenger receptor binding as compared to AM end-group functionality. Furthermore, AM coatings significantly prevented platelet adhesion to metal, demonstrating its potential as an anti-platelet therapy to treat thrombosis. Thus, AM micelles and NPs can effectively repress early stage SMC proliferation and thrombosis through non-cytotoxic mechanisms, highlighting the promise of nanomedicine for

  12. Nucleoside, nucleotide and oligonucleotide based amphiphiles: a successful marriage of nucleic acids with lipids.

    Science.gov (United States)

    Gissot, Arnaud; Camplo, Michel; Grinstaff, Mark W; Barthélémy, Philippe

    2008-04-21

    Amphiphilic molecules based on nucleosides, nucleotides and oligonucleotides are finding more and more biotechnological applications. This Perspective highlights their synthesis, supramolecular organization as well as their applications in the field of biotechnology.

  13. Amphiphile regulation of ion channel function by changes in the bilayer spring constant

    DEFF Research Database (Denmark)

    Lundbæk, Jens August; Koeppe, R.E.; Andersen, Oluf Sten

    2010-01-01

    effect of amphiphiles, at concentrations often used in biological research, on the bilayer elastic response to a change in the hydrophobic length of an embedded protein. The effects of structurally diverse amphiphiles can be described by changes in a phenomenological bilayer spring constant (H......Many drugs are amphiphiles that, in addition to binding to a particular target protein, adsorb to cell membrane lipid bilayers and alter intrinsic bilayer physical properties (e. g., bilayer thickness, monolayer curvature, and elastic moduli). Such changes can modulate membrane protein function......-B) that summarizes the bilayer elastic properties, as sensed by a bilayer-spanning protein. Amphiphile-induced changes in H-B, measured using gA channels of a particular length, quantitatively predict changes in lifetime for channels of a different length-as well as changes in the inactivation of voltage...

  14. Amphiphilic organoplatinum(II) complexes: Self-assembly in solution and at interfaces

    Science.gov (United States)

    Maran, Umamageswaran

    Organoplatinum(II) gemini amphiphiles with three different chain lengths and a predefined angle of 60° are synthesized. Self-organization at the air-water interface is investigated as a function of chain length and reduction in surface area, by using Langmuir-trough techniques. The atomic force microscopy (AFM) images of the transferred Langmuir-Schaefer (LS) films reveals wormlike aggregates for the organoplatinum(II) gemini amphiphiles, possessing hexyloxy- and dodecyloxy-chains. A neutral crown ether functionalized [1+1] facial amphiphile was self-assembled from a flexible 32-membered dibenzo crown ether and a diplatinum acceptor clip. A homologous series of charged triangle-shaped amphiphilic metallomacrocyles was self-assembled from stoichiometric amounts of organoplatinum(II) gemini amphiphiles and bipyridyl donor molecules in quantitative yields. The amphiphilic triangular scaffolds were characterized by multinuclear NMR and ESI-MS. A new amphiphilic organoplatinum(II) precursor with a predefined angle of 90° was synthesized. The precursor was mixed in stoichiometric ratios with two different 3-substituted pyridines and a rigid bipyridyl ligand to construct three charged amphiphilic metallomacrocyles. The computational calculations on the assemblies constructed from flexible 3-substituted pyridines indicate that the assemblies exist largely as chair isomers. The self-organization of the hexacationic triangular amphiphiles at liquid-liquid, air-water and solid-air interfaces was studied using confocal microscopy, in situ Raman spectroscopy, Langmuir-trough techniques, fluorescence spectroscopy and AFM. The amphiphilic triangle with octadecyloxy-chains was found to form a bicontinuous coacervate with pores in a chloroform/water solvent mixture. The pressure-area isotherms revealed formation of surface aggregates at the air-water interface. Fluid AFM studies on the transferred LS layers reveal ridge-like patterns with a flat top. Models were constructed to

  15. Amphiphilic oligoethyleneimine-β-cyclodextrin "click" clusters for enhanced DNA delivery.

    Science.gov (United States)

    Martínez, Álvaro; Bienvenu, Céline; Jiménez Blanco, José L; Vierling, Pierre; Mellet, Carmen Ortiz; García Fernández, José M; Di Giorgio, Christophe

    2013-08-16

    Monodisperse amphiphilic oligoethyleneimine (OEI)-β-cyclodextrin (βCD) clusters have been prepared, and their potential as gene delivery systems has been evaluated in comparison with a nonamphiphilic congener. The general prototype incorporates tetraethyleneimine segments linked to the primary rim of βCD through either triazolyl or thioureidocysteaminyl connectors. Transfection efficiency data for the corresponding CD:pDNA nanocomplexes (CDplexes) in BNL-CL2 murine hepatocytes evidenced the strong beneficial effect of facial amphiphilicity. PMID:23859761

  16. Long-Circulating 15 nm Micelles Based on Amphiphilic 3-Helix Peptide-PEG Conjugates

    OpenAIRE

    Dong, He; Dube, Nikhil; Shu, Jessica Y.; Seo, Jai W.; Mahakian, Lisa M; Ferrara, Katherine W.; Xu, Ting

    2012-01-01

    Generating stable, multi-functional organic nanocarriers will have a significant impact on drug formulation. However, it remains a significant challenge to generate organic nanocarriers with a long circulation half-life, effective tumor penetration and efficient clearance of metabolites. We have advanced this goal by designing a new family of amphiphiles based on coiled-coil 3-helix bundle forming peptide-poly(ethylene glycol) conjugates. The amphiphiles self-assemble into monodisperse micell...

  17. Synthesis and aggregation properties of amphiphilic mono and bisadducts of fullerene in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Pu Zhang; Zhi Xin Guo; Shuang Lv

    2008-01-01

    New amphiphilic[60]fullerene monoadduet TPF and bisadducts BTPF were synthesized and well-characterized. Their aggregation properties in aqueous solution was investigated by UV-vis and TEM methods. In aqueous solution, monoadduct TPF forms irregularly shaped and some rod-like aggregates, whereas bisadducts BTPF gives spherical aggregates with diameters of 50-150 nm. It indicated that the aggregation properties of amphiphilic fullerene derivatives depend on the number of hydrophilic appendage on the C60 cage.

  18. SYNTHESIS OF AMPHIPHILIC COMB-SHAPED COPOLYMERS USED FOR SURFACE MODIFICATION OF PVDF MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    徐又一

    2009-01-01

    The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4- hydroxyphenyl) maleimide)(SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate(PEGMA) side groups was achieved by atom transfer radical polymerization(ATRP).The amphiphilic copolymers were characterized by ~1H-NMR, Fourier transform infrared(FTIR) spectroscopy and gel permeation chromatography(GPC).From thermogravimetric analysis (TGA),the decomposition temperature of SHMI-g-PEGMA is low...

  19. Distributed localization for anchor-free sensor networks

    Institute of Scientific and Technical Information of China (English)

    Cui Xunxue; Shan Zhiguan; Liu Jianjun

    2008-01-01

    Geographic location of nodes is very useful in a sensor network. Previous localization algorithms assume that there exist some anchor nodes in this kind of network, and then other nodes are estimated to create their coordinates. Once there are not anchors to be deployed, those localization algorithms will be invalidated. Many papers in this field focus on anchor-based solutions. The use of anchors introduces many limitations, since anchors require external equipments such as global position system, cause additional power consumption. A novel positioning algorithm is proposed to use a virtual coordinate system based on a new concept-virtual anchor. It is executed in a distributed fashion according to the connectivity of a node and the measured distances to its neighbors. Both the adjacent member information and the ranging distance result are combined to generate the estimated position of a network, one of which is independently adopted for localization previously. At the position refinement stage the intermediate estimation of a node begins to be evaluated on its reliability for position mutation; thus the positioning optimization process of the whole network is avoided falling into a local optimal solution. Simulation results prove that the algorithm can resolve the distributed localization problem for anchor-free sensor networks, and is superior to previous methods in terms of its positioning capability under a variety of circumstances.

  20. Amphiphile self-assemblies in supercritical CO2 and ionic liquids.

    Science.gov (United States)

    Zhang, Jianling; Peng, Li; Han, Buxing

    2014-08-28

    Supercritical (sc) CO2 and ionic liquids (ILs) are very attractive green solvents with tunable properties. Using scCO2 and ILs as alternatives of conventional solvents (water and oil) for forming amphiphile self-assemblies has many advantages. For example, the properties and structures of the amphiphile self-assemblies in these solvents can be easily modulated by tuning the properties of solvents; scCO2 has excellent solvation power and mass-transfer characteristics; ILs can dissolve both organic and inorganic substances and their properties are designable to satisfy the requirements of various applications. Therefore, the amphiphile self-assemblies in scCO2 and ILs have attracted considerable attention in recent years. This review describes the advances of using scCO2 or/and ILs as amphiphile self-assembly media in the last decade. The amphiphile self-assemblies in scCO2 and ILs are first reviewed, followed by the discussion on combination of scCO2 and ILs in creating microemulsions or emulsions. Some future directions on the amphiphile self-assemblies in scCO2 and ILs are highlighted. PMID:25000970

  1. Neurostimulation leads, intrathecal catheters and anchoring devices evolution

    Directory of Open Access Journals (Sweden)

    Laura Demartini

    2015-03-01

    Full Text Available Many scientific studies highlight the usefulness of spinal cord stimulation and intrathecal therapy for the management of chronic pain syndromes resistant to pharmacological or less invasive interventional therapies. One of the possible complications of these techniques, reported in literature, is migration of the lead or catheter; thus the use of an anchoring system is considered mandatory. Every company that produces devices for neurostimulation or neuromodulation provides various anchoring devices evolved over time. In the study, the authors discuss about the most common anchoring devices based on their clinical experience.

  2. Amphiphilic star block copolymers as gene carrier Part I: Synthesis via ATRP using calix[4]resorcinarene-based initiators and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Anna; Xue, Yan; Wei, Dafu [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Guan, Yong, E-mail: yguan@ecust.edu.cn [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Xiao, Huining [Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3 (Canada)

    2013-01-01

    In this work, a cationic star polymer [poly(2-dimethylamino)ethyl methacrylate (PDMAEMA)] was prepared via atom transfer radical polymerization (ATRP), using brominated calix[4]resorcinarene as an initiator. Hydrophobic moieties, methyl methacrylate (MMA) and butyl acrylate (BA), were further incorporated via 'one-pot' method. Well-defined eight-armed star block copolymers bearing hydrophilic blocks inside and hydrophobic blocks outside were synthesized. The molecular weight, particle size, electrophoretic mobility and apparent charge density were determined by gel permeation chromatography (GPC), dynamic light scattering (DLS), phase analysis light scattering (PALS) and colloidal titration, respectively. The zeta potentials and apparent charge densities of the products exhibited the characteristics of polyelectrolyte. The incorporation of hydrophobic moieties generated electrostatic screening effect. The as-synthesized amphiphilic star copolymer is promising as a thermo-sensitive gene carrier for gene therapy. Highlights: Black-Right-Pointing-Pointer Amphiphilic cationic star block copolymers with well-controlled structures were prepared via ATRP. Black-Right-Pointing-Pointer The molecular structures and properties of the initiator and copolymers were systematically characterized. Black-Right-Pointing-Pointer The products exhibited the positive charged character, and hydrophobic moieties generated electrostatic screening effect.

  3. Material Testing for Robotic Omnidirectional Anchor

    Science.gov (United States)

    Witkoe, Kevin S.

    2012-01-01

    To successfully explore near-Earth Asteroids the question of mobility emerges as the key issue for any robotic mission. When small bodies have extremely low escape velocities, traditional methods, such as wheels, would send the robot hurtling off of the asteroid's surface. To solve this problem, JPL has developed an omni-directional anchoring mechanism for use in microgravity that utilizes microspine technology. These microspines are placed in circular arrays with 16 independent carriages biasing the surface of the rock. The asperities in the surface allow the gripper to hold nearly 150N in all directions. While the gripper has been proven successful on consolidated rocks, it had yet to be tested on a variety of other surfaces that are suspected to separate the large boulders on an asteroid. Since asteroid surfaces vary widely, from friable rocks to lose ponds of regolith, the gripper was tested in a large variety of materials such as, bonded pumice, sand, gravel, and loose rocks. The forces are applied tangent, at 45 degrees, and normal to the surface of the material. The immediate results from this experiment will give insight into the gripper's effectiveness across the wide spectrum of materials found on asteroids.

  4. Polymer Chemistry

    Science.gov (United States)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  5. Stable and robust polymer nanotubes stretched from polymersomes

    Science.gov (United States)

    Reiner, Joseph E.; Wells, Jeffrey M.; Kishore, Rani B.; Pfefferkorn, Candace; Helmerson, Kristian

    2006-01-01

    We create long polymer nanotubes by directly pulling on the membrane of polymersomes using either optical tweezers or a micropipette. The polymersomes are composed of amphiphilic diblock copolymers, and the nanotubes formed have an aqueous core connected to the aqueous interior of the polymersome. We stabilize the pulled nanotubes by subsequent chemical cross-linking. The cross-linked nanotubes are extremely robust and can be moved to another medium for use elsewhere. We demonstrate the ability to form networks of polymer nanotubes and polymersomes by optical manipulation. The aqueous core of the polymer nanotubes together with their robust character makes them interesting candidates for nanofluidics and other applications in biotechnology. cross-link | optical tweezers | nanofluidics | vesicles

  6. Liquid crystal director fluctuations and surface anchoring by molecular simulation

    OpenAIRE

    Andrienko, D.; Germano, G; Allen, M. P.

    2002-01-01

    We propose a simple and reliable method to measure the liquid crystal surface anchoring strength by molecular simulation. The method is based on the measurement of the long-range fluctuation modes of the director in confined geometry. As an example, molecular simulations of a liquid crystal in slab geometry between parallel walls with homeotropic anchoring have been carried out using the Monte Carlo technique. By studying different slab thicknesses, we are able to calculate separately the pos...

  7. Evaluation of the stability of anchor-reinforced slopes

    OpenAIRE

    Lee, CF; Zhu, DY; Chan, DH; Jiang, HD

    2005-01-01

    The conventional methods of slices are commonly used for the analysis of slope stability. When anchor loads are involved, they are often treated as point loads, which may lead to abrupt changes in the normal stress distribution on the potential slip surface. As such abrupt changes are not reasonable and do not reflect reality in the field, an alternative approach based on the limit equilibrium principle is proposed for the evaluation of the stability of anchor-reinforced slopes. With this app...

  8. Mechanical behaviour of adhesive anchors installed in concrete

    OpenAIRE

    Zavliaris, K.D.

    1990-01-01

    The thesis presents the main characteristics of the mechanical behaviour of adhesive anchors installed in concrete. They are the mechanisms of failure, the relationship between applied pull-out'loadand slip of the anchor and the stresses and strains in each of the three components (steel-resin'-concrete). The study is-primarily-experimental--but theoretical and finite element analyses are also included. These main characteristics are dependent on the'adhesion and wetting phenomena across the ...

  9. Transosseous Acetabular Labral Repair as an Alternative to Anchors

    OpenAIRE

    Pérez-Carro, Luis; Cabello, Andres Gonzalez; Rakha, Mohamed Ibrahim; Patnaik, Sarthak; Centeno, Elias; Miranda, Victor; Fernández, Ana Alfonso

    2015-01-01

    Labral tears are the most common pathology in patients undergoing hip arthroscopy and the most common cause of mechanical hip symptoms. Labral repair techniques have been described in the literature using suture anchors placed as close as possible to the acetabular rim without penetrating the articular surface. Optimal surgical technique for labral repair is very important, and an inappropriate entry point and guide angulation may lead to intra-articular penetration of the anchor, chondral da...

  10. The Effect of Anchoring Sutures on Medicinal Leech Mortality

    OpenAIRE

    Davila, Victor J.; Hoppe, Ian C.; Landi, Rocco; Ciminello, Frank S.

    2009-01-01

    Objective: The implementation of leech therapy for surgical flaps is not always logistically easy or comfortable for patients or healthcare providers. We examine different methods of placing sutures in the medicinal leech, Hirudo medicinalis, to make the implementation of leech therapy easier. Methods: Sixteen leeches were randomly divided into 3 groups: a control group, a deep anchoring suture group, and a superficial anchoring suture group. The leeches were observed to determine if either o...

  11. Biomimetic anchors applied to the host-guest antifouling functionalization of titanium substrates.

    Science.gov (United States)

    Cai, Xiao Yan; Li, Ning Ning; Chen, Jiu Cun; Kang, En-Tang; Xu, Li Qun

    2016-08-01

    A biomimetic strategy was developed for the construction of antifouling titanium oxide (Ti(oxide)) surfaces based on host-guest interactions. Two catecholic derivatives, dopamine 4-(phenylazo)benzamide (AZODopa) and dopamine 1-adamantanecarboxamide (AdaDopa) were synthesized and immobilized onto the Ti(oxide) surfaces. The guest molecules-anchored Ti(oxide) surfaces were further functionalized with zwitterionic heptakis[6-deoxy-6-(N-3-sulfopropyl-N,N-dimethylammonium ethyl sulfanyl)]-β-cyclodextrin (SBCD) and hydrophilic β-CD polymer (CDP). The surface elemental compositions and hydrophobic/hydrophilic properties of the Ti(oxide) surfaces before and after modification were characterized by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements, respectively. The antifouling properties of the modified Ti(oxide) surfaces were evaluated by the protein adsorption and bacterial adhesion assays. The zwitterionic SBCD- and hydrophilic CDP-functionalized Ti(oxide) surfaces can reduce the adsorption of bovine plasma fibrinogen and adhesion of Escherichia coli, as compared to the pristine and guest molecules-anchored Ti(oxide) surfaces. PMID:27135943

  12. Covalent Anchoring of Chloroperoxidase and Glucose Oxidase on the Mesoporous Molecular Sieve SBA-15

    Directory of Open Access Journals (Sweden)

    Martin Hartmann

    2010-02-01

    Full Text Available Functionalization of porous solids plays an important role in many areas, including heterogeneous catalysis and enzyme immobilization. In this study, large-pore ordered mesoporous SBA-15 molecular sieves were synthesized with tetraethyl orthosilicate (TEOS in the presence of the non-ionic triblock co-polymer Pluronic P123 under acidic conditions. These materials were grafted with 3 aminopropyltrimethoxysilane (ATS, 3-glycidoxypropyltrimethoxysilane (GTS and with 3 aminopropyltrimethoxysilane and glutaraldehyde (GA-ATS in order to provide covalent anchoring points for enzymes. The samples were characterized by nitrogen adsorption, powder X-ray diffraction, solid-state NMR spectroscopy, elemental analysis, diffuse reflectance fourier transform infrared spectroscopy and diffuse reflectance UV/Vis spectroscopy. The obtained grafted materials were then used for the immobilization of chloroperoxidase (CPO and glucose oxidase (GOx and the resulting biocatalysts were tested in the oxidation of indole. It is found that enzymes anchored to the mesoporous host by the organic moieties can be stored for weeks without losing their activity. Furthermore, the covalently linked enzymes are shown to be less prone to leaching than the physically adsorbed enzymes, as tested in a fixed-bed reactor under continuous operation conditions.

  13. Dilational surface rheology of polymer solutions

    Science.gov (United States)

    Noskov, B. A.; Bykov, A. G.

    2015-06-01

    The review concerns main achievements in dilational rheology of polymer adsorption films at the gas/liquid interfaces reported in the last fifteen years. The theoretical foundations of methods of surface rheology and the key results obtained in studies of solutions of amphiphilic nonionic polymers, polyelectrolytes, proteins and their complexes with low-molecular-mass surfactants are discussed. Interest in the surface dilational rheology is mainly caused by a small number of available experimental methods for investigation of the surface of liquids, by the fact that traditional methods of measurement of the surface tension that are widely used in studies of solutions of low-molecular-mass surfactants provide little information when applied to polymer solutions owing to very slow establishment of equilibrium as well as by weak dependence of the surface tension on the polymer concentration. Progress in the surface rheology is driven by the recent studies of the stability of foams and emulsions that demonstrated a key role of the dilational surface rheological properties in the dynamics of liquid-phase disperse systems. The bibliography includes 191 references.

  14. Anchor stud monotonic and cyclic shear tests. Final report

    International Nuclear Information System (INIS)

    In a prestressed concrete reactor vessel (PCRV), the main cavity liner and other cavity liners with large diameter/thickness (D/t) ratios are anchored to the concrete by anchor studs. These anchor studs are subject to shear loading resulting from prestressing, pressurization, temperature, and creep of the PCRV. The test program discussed in this report consists of both monotonic and cyclic testing of models simulating the prototype anchor stud/concrete assembly. The tests determined the shear stiffness characteristics of the 3/4-in.-diameter, one-piece Nelson anchor stud embedded in concrete and established its low-cycle fatigue life under displacement-controlled loading. The previously obtained results of Phase I and Phase II tests on two-piece anchor studs, along with high-cyclic fatigue data taken from the literature, are discussed and are plotted with the current, Phase III, results to form a displacement versus cycles to failure curve covering a useful range of design applications

  15. Anchor Plates in Two-Layered Cohesion Less Soils

    Directory of Open Access Journals (Sweden)

    Hamed Niroumand

    2010-01-01

    Full Text Available Problem statement: During the past few years a great number of experimental model and numerical analysis results on the uplift resistance of anchor plate embedded in homogeneous cohesion less soil has been reported by many researchers. A review of related literature shows that not much research has been done to analyze the performance of anchor plates in layered soils a problem, which is often encountered by the professional engineers in the field. Approach: This study presented the performance of the anchor plates in the cohesion less soil by different researchers. It was based on different previous researches, from the earliest till the most recent ones. The main aim of this research was focused on the prediction of the anchor plates behavior and the force in the layered cohesion less soils. Few laboratory studies were conducted to investigate the uplift capacity behavior of cohesion less soil by previous researchers. Results: The experimental and numerical investigation included uplift test on cohesion less soil by last researchers. The embedment ratio and the effect of density on uplift response were evaluated. This analysis was investigated experimentally and numerically behavior of anchor plates buried in two layered cohesion less soil. Although earlier researchers developed experimentally expressions to estimate the uplift capacity of irregular anchor plates in layered cohesion less soils. Conclusion: The study observed that the ultimate uplift capacity is dependent on the relative strength of the two layers, the depth ratio of embedment and the upper layer thickness ratio.

  16. Poor anchoring limits dyslexics' perceptual, memory, and reading skills.

    Science.gov (United States)

    Oganian, Yulia; Ahissar, Merav

    2012-07-01

    The basic deficits underlying the severe and persistent reading difficulties in dyslexia are still highly debated. One of the major topics of debate is whether these deficits are language specific, or affect both verbal and non-verbal stimuli. Recently, Ahissar and colleagues proposed the "anchoring-deficit hypothesis" (Ahissar, Lubin, Putter-Katz, & Banai, 2006), which suggests that dyslexics have a general difficulty in automatic extraction of stimulus regularities from auditory inputs. This hypothesis explained a broad range of dyslexics' verbal and non-verbal difficulties. However, it was not directly tested in the context of reading and verbal memory, which poses the main stumbling blocks to dyslexics. Here we assessed the abilities of adult dyslexics to efficiently benefit from ("anchor to") regularities embedded in repeated tones, orally presented syllables, and written words. We also compared dyslexics' performance to that of individuals with attention disorder (ADHD), but no reading disability. We found an anchoring effect in all groups: all gained from stimulus repetition. However, in line with the anchoring-deficit hypothesis, controls and ADHD participants showed a significantly larger anchoring effect in all tasks. This study is the first that directly shows that the same domain-general deficit, poor anchoring, characterizes dyslexics' performance in perceptual, working memory and reading tasks.

  17. Evaluation of mitral valve replacement anchoring in a phantom

    Science.gov (United States)

    McLeod, A. Jonathan; Moore, John; Lang, Pencilla; Bainbridge, Dan; Campbell, Gordon; Jones, Doug L.; Guiraudon, Gerard M.; Peters, Terry M.

    2012-02-01

    Conventional mitral valve replacement requires a median sternotomy and cardio-pulmonary bypass with aortic crossclamping and is associated with significant mortality and morbidity which could be reduced by performing the procedure off-pump. Replacing the mitral valve in the closed, off-pump, beating heart requires extensive development and validation of surgical and imaging techniques. Image guidance systems and surgical access for off-pump mitral valve replacement have been previously developed, allowing the prosthetic valve to be safely introduced into the left atrium and inserted into the mitral annulus. The major remaining challenge is to design a method of securely anchoring the prosthetic valve inside the beating heart. The development of anchoring techniques has been hampered by the expense and difficulty in conducting large animal studies. In this paper, we demonstrate how prosthetic valve anchoring may be evaluated in a dynamic phantom. The phantom provides a consistent testing environment where pressure measurements and Doppler ultrasound can be used to monitor and assess the valve anchoring procedures, detecting pararvalvular leak when valve anchoring is inadequate. Minimally invasive anchoring techniques may be directly compared to the current gold standard of valves sutured under direct vision, providing a useful tool for the validation of new surgical instruments.

  18. Probing into the Supramolecular Driving Force of an Amphiphilic β-Cyclodextrin Dimer in Various Solvents: Host-Guest Recognition or Hydrophilic-Hydrophobic Interaction?

    Science.gov (United States)

    Bai, Yang; Fan, Xiao-dong; Yao, Hao; Yang, Zhen; Liu, Ting-ting; Zhang, Hai-tao; Zhang, Wan-bin; Tian, Wei

    2015-09-01

    Tuning of the morphology and size of supramolecular self-assemblies is of theoretical and practical significance. To date, supramolecular driving forces in different solvents remain unclear. In this study, we first synthesized an amphiphilic β-cyclodextrin (β-CD) dimer that consists of one hydrophobic ibuprofen (Ibu) and two hydrophilic β-CD moieties (i.e., Ibu-CD2). Ibu-CD2 possesses double supramolecular driving forces, namely, the host-guest recognition and hydrophilic-hydrophobic interaction. The host-guest interaction of Ibu-CD2 induced the formation of branched supramolecular polymers (SPs) in pure water, whereas the hydrophilic-hydrophobic interaction generated spherical or irregular micelles in water/organic mixtures. The SP size increased with the increase in Ibu-CD2 concentration in pure water. By contrast, the size of micelles decreased with the increase in volume ratio of water in mixtures. PMID:26301920

  19. Polymers & People

    Science.gov (United States)

    Lentz, Linda; Robinson, Thomas; Martin, Elizabeth; Miller, Mary; Ashburn, Norma

    2004-01-01

    Each Tuesday during the fall of 2002, teams of high school students from three South Carolina counties conducted a four-hour polymer institute for their peers. In less than two months, over 300 students visited the Charleston County Public Library in Charleston, South Carolina, to explore DNA, nylon, rubber, gluep, and other polymers. Teams of…

  20. Polymer Informatics

    Science.gov (United States)

    Adams, Nico

    Polymers are arguably the most important set of materials in common use. The increasing adoption of both combinatorial as well as high-throughput approaches, coupled with an increasing amount of interdisciplinarity, has wrought tremendous change in the field of polymer science. Yet the informatics tools required to support and further enhance these changes are almost completely absent. In the first part of the chapter, a critical analysis of the challenges facing modern polymer informatics is provided. It is argued, that most of the problems facing the field today are rooted in the current scholarly communication process and the way in which chemists and polymer scientists handle and publish data. Furthermore, the chapter reviews existing modes of representing and communicating polymer information and discusses the impact, which the emergence of semantic technologies will have on the way in which scientific and polymer data is published and transmitted. In the second part, a review of the use of informatics tools for the prediction of polymer properties and in silico design of polymers is offered.

  1. Photochemical Isomerization and Topochemical Polymerization of the Programmed Asymmetric Amphiphiles

    Science.gov (United States)

    Kim, Dae-Yoon; Lee, Sang-A.; Jung, Daseal; Jeong, Kwang-Un

    2016-06-01

    For the advancement in multi-stimuli responsive optical devices, we report the elaborate molecular engineering of the dual photo-functionalized amphiphile (abbreviated as AZ1DA) containing both a photo-isomerizable azobenzene and a photo-polymerizable diacetylene. To achieve the efficient photochemical reactions in thin solid films, the self-assembly of AZ1DA molecules into the ordered phases should be precisely controlled and efficiently utilized. First, the remote-controllable light shutter is successfully demonstrated based on the reversible trans-cis photo-isomerization of azobenzene group in the smectic A mesophase. Second, the self-organized monoclinic crystal phase allows us to validate the photo-polymerization of diacetylene moiety for the photo-patterned thin films and the thermo-responsible color switches. From the demonstrations of optically tunable thin films, it is realized that the construction of strong relationships between chemical structures, molecular packing structures and physical properties of the programmed molecules is the core research for the development of smart and multifunctional soft materials.

  2. Tissue Regeneration through Self-Assembled Peptide Amphiphile Nanofibers

    Directory of Open Access Journals (Sweden)

    Hossein Hosseinkhani

    2006-01-01

    Full Text Available Introduction: In the present study, we hypothesized that a novelapproach to promote vascularization would be to create injectablethree dimensional (3-D scaffolds within growth factor that enhancethe sustained release of growth factor and induce the angiogenesis.Material and Methods: We demonstrate that a 3-D scaffold can beformed by mixing of peptide-amphiphile (PA aqueous solution withhepatocyte growth factor (HGF solution. PA was synthesized bystandard solid phase chemistry that ends with the alkylation of theNH2 terminus of the peptide. The sequence of arginine-glycineasparticacid (RGD was included in peptide design as well. A 3-Dnetwork of nanofibers was formed by mixing HGF suspensions withdilute aqueous solution of PA.Results: Scanning electron microscopy (SEM examination revealedthe formation of fibrous assemblies with an extremely high aspectratio and high surface areas with mean diameter of less than 200 nm.In vitro HGF release profile of 3-D nanofibers was investigated whileangiogenesis induced by the released HGF was being assessed. Invivo potential ability of PA nanofibers to induce angiogenesis wasassessed through subcutaneous injection of PA solution, HGFsolution, and PA in combination with HGF solutions. Injection of PAwith HGF induced significant angiogenesis around the injected site,in marked contrast to HGF injection alone and PA injection alone.Conclusion: The combination of HGF-induced angiogenesis is apromising procedure to improve tissue regeneration.

  3. Synthesis, aggregation, and chiroptical properties of chiral, amphiphilic dendrimers.

    Science.gov (United States)

    Laufersweiler, M J; Rohde, J M; Chaumette, J L; Sarazin, D; Parquette, J R

    2001-09-21

    The syntheses of amphiphilic dendrimers based on 3,5-dihydroxybenzyl alcohol containing tri- or tetrafunctional chiral central cores and allyl ester termini are described. Water solubility is imparted to the dendrimers via a palladium-catalyzed deprotection of the peripheral allyl esters. This method affords complete deprotection of the carboxylate surface because, in contrast to the basic hydrolysis of methyl ester termini, the solubility of partially hydrolyzed intermediates is maintained throughout the course of the deprotection, thereby avoiding precipitation during the reaction. Chiroptical analysis indicates that the structure of the dendrimers collapses in water, resulting in an increased steric effect upon the central core that is manifested by lower optical rotatory power. However, contributions to the chiroptical properties from the dendron branch segments were not evident in water or organic media, suggesting that chiral substructures were not developing in the branch segments of the dendrimers. Multiangle light scattering studies revealed that the dendrimers experienced significant aggregation in aqueous media that decreased at higher generations. This behavior could be rationalized by a change in conformational preference from a disklike conformation at low generations to a more globular conformation at higher generations. PMID:11559197

  4. Amphiphilic self-assembly of alkanols in protic ionic liquids.

    Science.gov (United States)

    Jiang, Haihui Joy; FitzGerald, Paul A; Dolan, Andrew; Atkin, Rob; Warr, Gregory G

    2014-08-21

    Strong cohesive forces in protic ionic liquids (PILs) can induce a liquid nanostructure consisting of segregated polar and apolar domains. Small-angle X-ray scattering has shown that these forces can also induce medium chain length n-alkanols to self-assemble into micelle- and microemulsion-like structures in ethylammonium (EA(+)) and propylammonium (PA(+)) PILs, in contrast to their immiscibility with both water and ethanolammonium (EtA(+)) PILs. These binary mixtures are structured on two distinct length scales: one associated with the self-assembled n-alkanol aggregates and the other with the underlying liquid nanostructure. This suggests that EA(+) and PA(+) enable n-alkanol aggregation by acting as cosurfactants, which EtA(+) cannot do because its terminating hydroxyl renders the cation nonamphiphilic. The primary determining factor for miscibility and self-assembly is the ratio of alkyl chain lengths of the alkanol and PIL cation, modulated by the anion type. These results show how ILs can support the self-assembly of nontraditional amphiphiles and enable the creation of new forms of soft matter. PMID:25068766

  5. Optimization of hypocrellin B derivative amphiphilicity and biological activity

    Institute of Scientific and Technical Information of China (English)

    LIU Xin; XIE Jie; ZHANG LuYong; CHEN HongXia; GU Ying; ZHAO JingQuan

    2009-01-01

    To satisfy the dual requirements of the fluent transportation in blood and the affinity to the target tissues of vascular diseases, hypocrellin derivatives with optimized amphiphilicity are expected. In this work, 3-amino-1-propanesulfonic acid and 4-amino-1-butanesulfonic acid substituted hypocrellin B,named compounds 1 and 2, were designed, synthesized in high yields and characterized. Besides greatly strengthened red absorption, the maximum solubility of compound 2 in phosphate buffered saline (PBS) is 4.2 mg/mL which is just enough to prepare an aqueous solution for intravenous injection in clinically acceptable concentration, while the partition coefficient between n-octanol and PBS,5.6, benefits the cell-uptake and biological activity as well. Furthermore, EPR measurements reveal that the photosensitization activities of the two compounds to generate semiquinone anion radicals, superoxide anion radicals and singlet oxygen are a little bit higher than those of taurine substituted hypocrellin B (THB), but the photodynamic activities to human lung cancer A549 cells are several times that of THB, mainly due to increases in lipophilicity and cell-uptake.

  6. Synthesis and Bioactivities of Kanamycin B-Derived Cationic Amphiphiles.

    Science.gov (United States)

    Fosso, Marina Y; Shrestha, Sanjib K; Green, Keith D; Garneau-Tsodikova, Sylvie

    2015-12-10

    Cationic amphiphiles derived from aminoglycosides (AGs) have been shown to exhibit enhanced antimicrobial activity. Through the attachment of hydrophobic residues such as linear alkyl chains on the AG backbone, interesting antibacterial and antifungal agents with a novel mechanism of action have been developed. Herein, we report the design and synthesis of seven kanamycin B (KANB) derivatives. Their antibacterial and antifungal activities, along with resistance/enzymatic, hemolytic, and cytotoxicity assays were also studied. Two of these compounds, with a C12 and C14 aliphatic chain attached at the 6″-position of KANB through a thioether linkage, exhibited good antibacterial and antifungal activity, were poorer substrates than KANB for several AG-modifying enzymes, and could delay the development of resistance in bacteria and fungi. Also, they were both relatively less hemolytic than the known membrane targeting antibiotic gramicidin and the known antifungal agent amphotericin B and were not toxic at their antifungal MIC values. Their oxidation to sulfones was also demonstrated to have no effect on their activities. Moreover, they both acted synergistically with posaconazole, an azole currently used in the treatment of human fungal infections. PMID:26592740

  7. Self-assembly of ssDNA-amphiphiles into micelles, nanotapes and nanotubes

    Science.gov (United States)

    Pearce, Timothy R.

    The field of DNA nanotechnology utilizes DNA as a construction material to create functional supramolecular and multi-dimensional structures like two-dimensional periodic lattices and three-dimensional polyhedrons with order on the nanometer scale for many nanotechnology applications including molecular templating, nanosensors, and drug delivery. Single-stranded DNA (ssDNA) is often used to create these nanostructures as the DNA bases provide an intrinsic molecular code that can be exploited to allow for the programmed assembly of structures based upon Watson-Crick base-pairing. However, engineering these complex structures from biopolymers alone requires careful design to ensure that the intrinsic forces responsible for organizing the materials can produce the desired structures. Additional control over supramolecular assembly can be achieved by chemically modifying the ssDNA with hydrophobic moieties to create amphiphilic molecules, which adds the hydrophobic interaction to the list of contributing forces that drive the self-assembly process. We first explored the self-assembly behavior of a set of ssDNA aptamer-amphiphiles composed of the same hydrophobic tail and hydrophilic ssDNA aptamer headgroup but with different spacer molecules linking these groups together. Through the use of cryo-transmission electron microscopy (cryo-TEM), small angle x-ray scattering (SAXS), and circular dichroism (CD) we show that the aptamer-amphiphiles can assemble into a variety of structures depending on the spacer used. We demonstrated, for the first time, the creation of self-assembled aptamer-amphiphile nanotape structures and show that the choice of the spacer used in the design of aptamer-amphiphiles can influence their supramolecular self-assembly as well as the secondary structure of the aptamer headgroup. We next explored the role of the ssDNA headgroup on the amphiphile self-assembly behavior by designing amphiphiles with headgroups of multiple lengths and nucleotides

  8. Polymer supported nickel complex: Synthesis, structure and catalytic application

    Indian Academy of Sciences (India)

    Alekha Kumar Sutar; Tungabidya Maharana; Yasobanta Das; Prasanta Rath

    2014-11-01

    In the present investigation, a new synthetic route for a novel recyclable free [3-MOBdMBn-Ni] and polystyrene-anchored [P-3-MOBdMBn-Ni] nickel complexes is presented. The free and polymer-anchored metal complexes were synthesized by the reaction of nickel (II) with one molar equivalent of unsupported N N′-bis (2-Hydroxy-3-methoxybenzaldehyde) 4-Methylbenzene-1,2-diamine (3-MOBdMBn) or polymersupported (P-3-MOBdMBn) Schiff-base ligand in methanol under nitrogen atmosphere. The advantages of these polymer-supported catalysts are the low cost of catalyst and recyclability up to six times, due to easy availability of materials and simple synthetic route. The higher efficiency of complexation of nickel on the polymer-anchored 3-MOBdMBn Schiff base than the unsupported analogue is another advantage of this catalyst system. The structural study reveals that nickel(II) complex of 3-MOBdMBn is square planar in geometry. The catalytic activity of nickel complex towards the oxidation of phenol was investigated in the presence of hydrogen peroxide. Experimental results indicate that the reactivity of P-3-MOBdMBn-Ni was dramatically affected by the polymer support compared to free 3-MOBdMBn-Ni. The rates of oxidation (R) for unsupported and supported catalysts are 1.37 × 10-6 mole dm-3 s-1 and 2.33 × 10-6 mole dm-3 s-1 respectively.

  9. Cholesterol-Targeted Anticancer and Apoptotic Effects of Anionic and Polycationic Amphiphilic Cyclodextrin Nanoparticles.

    Science.gov (United States)

    Varan, Gamze; Öncül, Selin; Ercan, Ayşe; Benito, Juan M; Ortiz Mellet, Carmen; Bilensoy, Erem

    2016-10-01

    Amphiphilic cyclodextrins (CDs) are biocompatible derivatives of natural CDs and are able to form nanoparticles or polyplexes spontaneously. In this study, nanoparticles prepared from nonionic (6OCaproβCD) or cationic amphiphilic CD (PC βCDC6) were used comparatively to develop nanoparticles intended for breast cancer therapy. The characterization of these nanoparticles was performed both by in vitro and cell culture studies. Furthermore, the apoptotic and cytotoxic effects of blank amphiphilic CDs were demonstrated by various mechanistic methods including Caspase-8 activity, lipid peroxidation assay, TUNEL assay, Tali(®)-based image analysis, cholesterol assay, and gene expression studies. Blank nanoparticles exerted cytotoxicity against a variety of cancer cells (MCF-7, HeLa, HepG2, and MB49) but none to healthy cells (L929, G/G). Interestingly, blank 6OCaproβCD and blank PC βCDC6 derivatives were found to be intrinsically effective on cell number and membrane integrity of MCF-7 cells in apoptosis studies. Further in-depth studies were performed to elucidate the selective mechanism of anticancer action in MCF-7 cells caused by these amphiphilic CDs. In conclusion, blank amphiphilic CD nanoparticles induced apoptosis through mitochondrial pathway targeted to cholesterol microdomains in cancer cell membrane. PMID:27488900

  10. Fluorinated amphiphiles control the insertion of α-hemolysin pores into lipid bilayers.

    Science.gov (United States)

    Raychaudhuri, Pinky; Li, Qiuhong; Mason, Amy; Mikhailova, Ellina; Heron, Andrew J; Bayley, Hagan

    2011-03-15

    The insertion of fully folded and assembled ion channels and pores into planar lipid bilayers for electrical recording has been facilitated by the use of conventional detergents at a final concentration below the critical micelle concentration (CMC). After the desired number of channels or pores (often one) has been incorporated into a bilayer, it is important to prevent further insertion events, which is often done by awkward techniques such as perfusion. Here, we show that the addition of single-chain fluorinated amphiphiles (F-amphiphiles) with zwitterionic, simple neutral, and neutral oligomeric headgroups at a concentration above the CMC prevents the further insertion of staphylococcal α-hemolysin pores, MspA pores, and Kcv potassium channels into lipid bilayers. We found the commercially available F(6)FC (fluorinated fos-choline with a C(6)F(13)C(2)H(4) chain) to be the least perturbing and most effective agent for this purpose. Bilayers are known to be resistant to F-amphiphiles, which in this case we suppose sequester the pores and channels within amphiphile aggregates. We suggest that F-amphiphiles might be useful in the fabrication of bilayer arrays for nanopore sensor devices and the rapid screening of membrane proteins. PMID:21275394

  11. Protein Modification with Amphiphilic Block Copoly(2-oxazoline)s as a New Platform for Enhanced Cellular Delivery

    KAUST Repository

    Tong, Jing

    2010-08-02

    Several homopolymers, random copolymers and block copolymers based on poly(2-oxazoline)s (POx) were synthesized and conjugated to horseradish peroxidase (HRP) using biodegradable and nonbiodegradable linkers. These conjugates were characterized by amino group titration, polyacrylamide gel electrophoresis (PAGE), isoelectric focusing, enzymatic activity assay and conformation analysis. The conjugates contained on average from about one to two polymer chains per enzyme. From 70% to 90% of enzymatic activity was retained in most cases. Circular dichroism (CD) analysis revealed that HRP modification affected the secondary structure of the apoprotein but did not affect the tertiary structure and heme environment. Enhanced cellular uptake was found in the conjugates of two block copolymers using both MDCK cells and Caco-2 cells, but not in the conjugates of random copolymer and homopolymer. Conjugation with a block copolymer of 2-methyl-2-oxazoline and 2-butyl-2-oxazoline led to the highest cellular uptake as compared to other conjugates. Our data indicates that modification with amphiphilic POx has the potential to modulate and enhance cellular delivery of proteins.

  12. Magnetic core–bilayer shell complex of magnetite nanoparticle stabilized with mPEG–polyester amphiphilic block copolymer

    International Nuclear Information System (INIS)

    In this article, we report the synthesis of magnetite nanoparticles (Fe3O4) coated with methoxy poly(ethylene glycol) (mPEG)–polyester amphiphilic block copolymers. The coating polymer layer contains a hydrophobic inner layer of polyester and a hydrophilic corona of mPEG. The copolymers were first prepared via a direct condensation between diacid, diol compounds and mPEG oligomer to obtain a hydrophobic polyester block and hydrophilic mPEG block and then “grafted onto” a magnetite nanoparticle surface. The copolymer composition was varied by changing the structure of the diacid, diol, and the molecular weight ( M-bar n ) of the mPEG such that particles with good dispersibility and stability in water were obtained. It was found that the copolymer prepared from 1,6-hexanediol can effectively stabilize the particles in water regardless of the types of diacid and M-bar n of mPEG used. The particle size was approximately 10 nm in diameter, and the particle dispersibility in water was quite dependent on the type and concentration of the copolymer used. Thermogravimetric analysis revealed the presence of less than 37 % Fe3O4 and about 48–53 % of the copolymer in the complexes. The percent entrapment efficiency and loading efficiency of indomethacin model drug in the copolymer-coated magnetite nanoparticles were 19 and 77 %, respectively

  13. Preparation of amphiphilic glycopolymers with flexible long side chain and their use as stabilizer for emulsion polymerization.

    Science.gov (United States)

    Alvárez-Paino, Marta; Juan-Rodríguez, Rafael; Cuervo-Rodríguez, Rocío; Muñoz-Bonilla, Alexandra; Fernández-García, Marta

    2014-03-01

    A glycomonomer was synthesized from poly(ethylene glycol) methacrylate (PEGMA). The terminal hydroxyl moieties were activated with ester groups and subsequently the glucosamine was incorporated forming urethane linkages. The obtained glycomonomer was copolymerized with methyl acrylate by free radical polymerization varying the initial feed composition to produce different amphiphilic glycopolymers. The glycopolymers were then characterized and compared with the homologous glycopolymers based on 2-{[(D-glucosamin-2-N-yl)carbonyl]oxy}ethyl methacrylate. Both series of glycopolymers were used in emulsion polymerization of methyl acrylate as stabilizers without the addition of any cosurfactant. Although high conversions were not achieved with any of the employed surfactant, the glycopolymers provide good colloidal stability, spherical, monodisperse and small latex particles in comparison with the surfactant-free emulsion polymerization. The latex particles stabilized with the glycosurfactant based on PEGMA, containing a flexible spacer between the backbone and the glucosamine, lead to smooth films whereas the short side chain surfactant from 2-hydroxyethyl methacrylate (HEMA), with higher glass transition temperature, restricts the coalescence of particles and, therefore, the film formation. Moreover, the surface bioactivity of these polymer coatings was examined by analyzing their specific interaction with the lectin, Concanavalin A, Canavalia ensiformis. The specific and successful binding to the Concanavalin A was demonstrated by fluorescence microscopy for both series being more intense with increasing amount of glycounits in the glycopolymer stabilizers. Interestingly, the incorporation of a flexible spacer in the glycopolymer structures enhances the binding activity.

  14. ULTRAFILTRATION AS PRETREATMENT OF REVERSE OSMOSIS: LOW FOULING ULTRAFILTRATION MEMBRANE PREPARED FROM POLYETHERSULFONE–AMPHIPHILIC BLOCK COPOLYMER BLEND

    Directory of Open Access Journals (Sweden)

    Heru Susanto

    2012-02-01

    Full Text Available This paper demonstrates the preparation of polyethersulfone (PES ultrafiltration (UF membranes via wet phase inversion method using either poly(ethylene oxide-b-poly(propylene oxide-b- poly(ethylene oxide (Pluronic®, Plu or polyethylene glycol (PEG as hydrophilic modifier. Their effects on membrane structure as well as the resulting membrane performance and their stability in membrane polymer matrix were systematically investigated. The investigated membrane characteristics include surface hydrophilicity (by contact angle, surface chemistry (by FTIR spectroscopy and water flux measurement. Visualization of membrane surface and cross section morphology was also done by scanning electron microscopy. The membrane performance was examined by investigation of adsorptive fouling and ultrafiltration using solution of bovine serum albumin as the model system. The stability of additive was examined by incubating the membrane in water (40oC for up to 10 days. The results show that modification effects on membrane characteristic and low fouling behavior were clearly observed. Further, amphiphilic Pluronic generally showed better performance than PEG.   

  15. Magnetic core–bilayer shell complex of magnetite nanoparticle stabilized with mPEG–polyester amphiphilic block copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Mekkapat, Supachai; Thong-On, Bandit; Rutnakornpituk, Boonjira; Wichai, Uthai; Rutnakornpituk, Metha, E-mail: methar@nu.ac.th [Naresuan University, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science (Thailand)

    2013-11-15

    In this article, we report the synthesis of magnetite nanoparticles (Fe{sub 3}O{sub 4}) coated with methoxy poly(ethylene glycol) (mPEG)–polyester amphiphilic block copolymers. The coating polymer layer contains a hydrophobic inner layer of polyester and a hydrophilic corona of mPEG. The copolymers were first prepared via a direct condensation between diacid, diol compounds and mPEG oligomer to obtain a hydrophobic polyester block and hydrophilic mPEG block and then “grafted onto” a magnetite nanoparticle surface. The copolymer composition was varied by changing the structure of the diacid, diol, and the molecular weight ( M-bar {sub n} ) of the mPEG such that particles with good dispersibility and stability in water were obtained. It was found that the copolymer prepared from 1,6-hexanediol can effectively stabilize the particles in water regardless of the types of diacid and M-bar {sub n} of mPEG used. The particle size was approximately 10 nm in diameter, and the particle dispersibility in water was quite dependent on the type and concentration of the copolymer used. Thermogravimetric analysis revealed the presence of less than 37 % Fe{sub 3}O{sub 4} and about 48–53 % of the copolymer in the complexes. The percent entrapment efficiency and loading efficiency of indomethacin model drug in the copolymer-coated magnetite nanoparticles were 19 and 77 %, respectively.

  16. Perceptual anchoring in preschool children: not adultlike, but there.

    Directory of Open Access Journals (Sweden)

    Karen Banai

    Full Text Available BACKGROUND: Recent studies suggest that human auditory perception follows a prolonged developmental trajectory, sometimes continuing well into adolescence. Whereas both sensory and cognitive accounts have been proposed, the development of the ability to base current perceptual decisions on prior information, an ability that strongly benefits adult perception, has not been directly explored. Here we ask whether the auditory frequency discrimination of preschool children also improves when given the opportunity to use previously presented standard stimuli as perceptual anchors, and whether the magnitude of this anchoring effect undergoes developmental changes. METHODOLOGY/PRINCIPAL FINDINGS: Frequency discrimination was tested using two adaptive same/different protocols. In one protocol (with-reference, a repeated 1-kHz standard tone was presented repeatedly across trials. In the other (no-reference, no such repetitions occurred. Verbal memory and early reading skills were also evaluated to determine if the pattern of correlations between frequency discrimination, memory and literacy is similar to that previously reported in older children and adults. Preschool children were significantly more sensitive in the with-reference than in the no-reference condition, but the magnitude of this anchoring effect was smaller than that observed in adults. The pattern of correlations among discrimination thresholds, memory and literacy replicated previous reports in older children. CONCLUSIONS/SIGNIFICANCE: The processes allowing the use of context to form perceptual anchors are already functional among preschool children, albeit to a lesser extent than in adults. Nevertheless, immature anchoring cannot fully account for the poorer frequency discrimination abilities of young children. That anchoring is present among the majority of typically developing preschool children suggests that the anchoring deficits observed among individuals with dyslexia represent a

  17. Tea stains-inspired initiator primer for surface grafting of antifouling and antimicrobial polymer brush coatings.

    Science.gov (United States)

    Pranantyo, Dicky; Xu, Li Qun; Neoh, Koon-Gee; Kang, En-Tang; Ng, Ying Xian; Teo, Serena Lay-Ming

    2015-03-01

    Inspired by tea stains, plant polyphenolic tannic acid (TA) was beneficially employed as the primer anchor for functional polymer brushes. The brominated TA (TABr) initiator primer was synthesized by partial modification of TA with alkyl bromide functionalities. TABr with trihydroxyphenyl moieties can readily anchor on a wide range of substrates, including metal, metal oxide, polymer, glass, and silicon. Concomitantly, the alkyl bromide terminals serve as initiation sites for atom transfer radical polymerization (ATRP). Cationic [2-(methacryloyloxy)ethyl]trimethylammonium chloride (META) and zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) and N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine (SBMA) were graft-polymerized from the TABr-anchored stainless steel (SS) surface. The cationic polymer brushes on the modified surfaces are bactericidal, while the zwitterionic coatings exhibit resistance against bacterial adhesion. In addition, microalgal attachment (microfouling) and barnacle cyprid settlement (macrofouling) on the functional polymer-grafted surfaces were significantly reduced, in comparison to the pristine SS surface. Thus, the bifunctional TABr initiator primer provides a unique surface anchor for the preparation of functional polymer brushes for inhibiting both microfouling and macrofouling. PMID:25650890

  18. Redox-sensitive micelles assembled from amphiphilic mPEG-PCL-SS-DTX conjugates for the delivery of docetaxel.

    Science.gov (United States)

    Zhang, Huiyuan; Wang, Kaiming; Zhang, Pei; He, Wenxiu; Song, Aixin; Luan, Yuxia

    2016-06-01

    Docetaxel (DTX) can produce anti-tumor effects by inhibiting cell growth and inducing apoptosis. However, the poor solubility of DTX restricts its application and its clinical formulation has caused serious adverse reaction due to the use of Tween-80. In the present study, DTX was conjugated to an amphiphilic di-block polymer to solve these problems. Methoxy poly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) was selected as the polymer skeleton and a redox sensitive disulfide bond was used as the linker between DTX and mPEG-PCL. The synthesized mPEG-PCL-SS-DTX conjugates were characterized by (1)H-nuclear magnetic resonance ((1)H NMR) and Fourier transform infrared spectroscopy (FTIR). Interestingly, the mPEG-PCL-SS-DTX conjugates could self-assemble into micelles in aqueous solution. The critical micelle concentration (CMC) of mPEG-PCL-SS-DTX micelles was about 2.3mgL(-1) determined using pyrene molecule fluorescent probe method while the size of mPEG-PCL-SS-DTX micelles was determined to be ca. 17.6nm and 116.0nm with a bimodal distribution by dynamic light scattering (DLS). The in vitro release results indicated that the as-prepared micelles exhibited a sustained release profile with good redox sensitive properties. In particular, the hemolytic toxicity test indicated the as-prepared mPEG-PCL-SS-DTX micelles had negligible hemolytic activity, demonstrating their safety in drug delivery system. Cytotoxicity assay of the mPEG-PCL-SS-DTX micelles verified their highly enhanced cytotoxicity to MCF-7/A and A549 cells. These results thus demonstrated that the present redox-sensitive mPEG-PCL-SS-DTX micelle was an efficient and safe sustained drug delivery system in the biomedical area.

  19. Effect of gelatin on micellization and microstructural behavior of amphiphilic amitriptyline hydrochloride drug solution: A detailed study

    International Nuclear Information System (INIS)

    Highlights: • Interaction between (AMT + gelatin) mixtures has been investigated. • The cac, psp, Nagg and ΔGagg are evaluated. • Interaction of AMT and gelatin forms highly surface active complex as disclosed by decreasing of ST of gelatin solution. • The 1H NMR spectroscopy was used to probe the molecular investigation between (drug + gelatin) mixtures. • CD spectra confirmed the electrostatic interactions between AMT and binding sites of gelatin. - Abstract: Herein we have investigated the dealings between amphiphilic antidepressant drug amitriptyline hydrochloride (AMT) and gelatin interaction using different proposed techniques. AMT is used for the treatment of mental/mood problems such as depression. Gelatin interacts with this drug alike fashions to the interaction of polymers and surfactants i.e., critical aggregation concentration (cac) and polymer saturation point (psp) were together achieved significantly. AMT and gelatin interaction starts due to the highly surface active complex formation as disclosed by decreasing of surface tension of gelatin solution by adding of AMT. It was uncovered from results that cac decreases on increasing the gelatin concentrations, whereas psp increases which is a sign of the attraction between AMT and gelatin. Thermodynamic parameters were also evaluated and discussed in detail. Fluorescence measurements were used to find the values of average aggregation numbers (Nagg) and various other parameters like Stern–Volmer constant (Ksv) and micropolarity. The nuclear magnetic resonance (1H NMR) data suggested that AMT interacts with gelatin by the means of hydrophobic interaction. The 1H NMR experiments explain that the extent of chemical shifts (δ) and line width (lw) increases with the increase in gelatin concentration. Secondary structure of gelatin was also examined via circular dichroism (CD) technique at different concentration of AMT. CD results confirmed that with increasing drug concentration the random

  20. An Analysis for Cross Beam-Ground Anchor Reinforcement

    Institute of Scientific and Technical Information of China (English)

    Xu Yingzi; Zhang Baiqing; Tang Huiming

    2005-01-01

    With the rapid development of water facilities, hydroelectric projects, highways and railways in China, beam-anchor reinforcement has been widely used to stabilize slopes in recent years. But the theory for the design of beam-anchor reinforcement is far behind the application. Cross beam-ground anchor reinforcement is a combination of beams and anchors forming a new structure to prevent slope sliding. The forces in the beams are discussed using theoretical analysis and numerical modeling. The Winkler model is used to analyze the beams, and reasonable values of λ, length, spacing and cantilevered length for the beams are determined through a theoretical analysis. A three-dimensional finite element method is adopted to model the interaction of the beams and soils and a structure analysis is applied to treat the beams and to study the stress distribution in external and internal beams. The analytical results show that it is better to satisfy λ≥2π, the spacing between anchors ls should be lsλ<π/2 and cantilever length should be (0.3-0.5)ls for the optimum design. The numerical results show that the same design can be used for all beams in different directions, including the internal and external beams. The application of the analytical method for reinforcement beam analysis is acceptable. It is better to choose a safety coefficient of 1.3 for design based on the analytical method for safety.

  1. Anchoring a Leviathan: How the Nuclear Membrane Tethers the Genome.

    Science.gov (United States)

    Czapiewski, Rafal; Robson, Michael I; Schirmer, Eric C

    2016-01-01

    It is well established that the nuclear envelope has many distinct direct connections to chromatin that contribute to genome organization. The functional consequences of genome organization on gene regulation are less clear. Even less understood is how interactions of lamins and nuclear envelope transmembrane proteins (NETs) with chromatin can produce anchoring tethers that can withstand the physical forces of and on the genome. Chromosomes are the largest molecules in the cell, making megadalton protein structures like the nuclear pore complexes and ribosomes seem small by comparison. Thus to withstand strong forces from chromosome dynamics an anchoring tether is likely to be much more complex than a single protein-protein or protein-DNA interaction. Here we will briefly review known NE-genome interactions that likely contribute to spatial genome organization, postulate in the context of experimental data how these anchoring tethers contribute to gene regulation, and posit several hypotheses for the physical nature of these tethers that need to be investigated experimentally. Significantly, disruption of these anchoring tethers and the subsequent consequences for gene regulation could explain how mutations in nuclear envelope proteins cause diseases ranging from muscular dystrophy to lipodystrophy to premature aging progeroid syndromes. The two favored hypotheses for nuclear envelope protein involvement in disease are (1) weakening nuclear and cellular mechanical stability, and (2) disrupting genome organization and gene regulation. Considerable experimental support has been obtained for both. The integration of both mechanical and gene expression defects in the disruption of anchoring tethers could provide a unifying hypothesis consistent with both.

  2. Tuning peptide amphiphile supramolecular structure for biomedical applications

    Science.gov (United States)

    Pashuck, Eugene Thomas, III

    The use of biomaterials in regenerative medicine has been an active area of research for more than a decade. Peptide amphiphiles, which are short peptide sequences coupled to alkyl tails, have been studied in the Stupp group since the beginning of the decade and been used for a variety of biomedical applications. Most of the work has focused on the bioactive epitopes places on the periphery of the PA molecules, but the interior amino acids, known as the beta-sheet region, give the PA nanofiber gel much of its mechanical strength. To study the important parameters in the beta-sheet region, six PA molecules were constructed to determine the influence of beta-sheet length and order of the amino acids in the beta-sheet. It was found that having beta-sheet forming amino acids near the center of the fiber improves PA gel stiffness, and that having extra amino acids that have preferences for other secondary structures, like alpha-helix decreased the gels stiffness. Using FTIR and circular dichroism it was found that the mechanical properties are influenced by the amount of twist in the beta-sheet, and PAs that have more twisted beta-sheets form weaker gels. The effect amino acid properties have on peptide amphiphile self-assembly where studied by synthesizining molecules with varying side group size and hydrophobicity. It was found that smaller amino acids lead to stiffer gels and when two amino acids had the same size the amino acid with the larger beta-sheet propensity lead to a stiffer gel. Furthermore, small changes in peptide structure were found to lead to big changes in nanostructure, as leucine and isoleucine, which have the same size but slightly different structures, form flat ribbons and cylindrical nanofibers, respectively. Phenylalanine and alanine were studied more indepth because they represent the effects of adding an aromatic group to amino acids in the beta-sheet regon. These phenylalanine PAs formed short, twisted ribbons when freshly dissolved in water

  3. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    Giuseppina Raffaini

    2015-12-01

    Full Text Available Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a “bottom up” approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD, which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties.

  4. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations.

    Science.gov (United States)

    Raffaini, Giuseppina; Mazzaglia, Antonino; Ganazzoli, Fabio

    2015-01-01

    Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a "bottom up" approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD), which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties. PMID:26734094

  5. Biomimetic Self-Templated Hierarchical Structures of Collagen-Like Peptide Amphiphiles.

    Science.gov (United States)

    Jin, Hyo-Eon; Jang, Jaein; Chung, Jinhyo; Lee, Hee Jung; Wang, Eddie; Lee, Seung-Wuk; Chung, Woo-Jae

    2015-10-14

    Developing hierarchically structured biomaterials with tunable chemical and physical properties like those found in nature is critically important to regenerative medicine and studies on tissue morphogenesis. Despite advances in materials synthesis and assembly processes, our ability to control hierarchical assembly using fibrillar biomolecules remains limited. Here, we developed a bioinspired approach to create collagen-like materials through directed evolutionary screening and directed self-assembly. We first synthesized peptide amphiphiles by coupling phage display-identified collagen-like peptides to long-chain fatty acids. We then assembled the amphiphiles into diverse, hierarchically organized, nanofibrous structures using directed self-assembly based on liquid crystal flow and its controlled deposition. The resulting structures sustained and directed the growth of bone cells and hydroxyapatite biominerals. We believe these self-assembling collagen-like amphiphiles could prove useful in the structural design of tissue regenerating materials. PMID:26392232

  6. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

    Science.gov (United States)

    Mazzaglia, Antonino; Ganazzoli, Fabio

    2015-01-01

    Summary Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a “bottom up” approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD), which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties. PMID:26734094

  7. High Selective Performance of Designed Antibacterial and Anticancer Peptide Amphiphiles.

    Science.gov (United States)

    Chen, Cuixia; Chen, Yucan; Yang, Cheng; Zeng, Ping; Xu, Hai; Pan, Fang; Lu, Jian Ren

    2015-08-12

    Short designed peptide amphiphiles are attractive at killing bacteria and inhibiting cancer cell growth, and the flexibility in their structural design offers a great potential for improving their potency and biocompatibility to mammalian host cells. Amino acid sequences such as G(IIKK)nI-NH2 (n≥3) have been shown to be membrane lytic, but terminal amino acid modifications could impose a huge influence on their performance. We report in this work how terminal amino acid modifications to G(IIKK)3I-NH2 influence its α-helical structure, membrane penetrating ability, and selective actions against different cell types. Deletion of an N-terminal Gly or a C-terminal Ile did not affect their antibacterial activity much, an observation consistent with their binding behavior to negatively charged membrane lipid monolayers. However, the cytotoxicity against mammalian cells was much worsened by the N-terminal Gly deletion, consistent with an increase in its helical content. Despite little impact on the antibacterial activity of G(IIKK)3I-NH2, deletion of both terminal amino acids greatly reduced its antitumor activity. Cholesterol present in tumor cell membrane-mimic was thought to constrain (IIKK)3-NH2 from penetrating into the cancerous membranes, evident from its lowest surface physical activity at penetrating model lipid membranes. On the other hand, its low toxicity to normal mammalian cells and high antibacterial activity in vitro and in vivo made it an attractive antibacterial agent. Thus, terminal modifications can help rebalance the different interactions involved and are highly effective at manipulating their selective membrane responses.

  8. Self-assembly mechanisms of nanofibers from peptide amphiphiles in solution and on substrate surfaces

    Science.gov (United States)

    Liao, Hsien-Shun; Lin, Jing; Liu, Yang; Huang, Peng; Jin, Albert; Chen, Xiaoyuan

    2016-08-01

    We report the investigation of the self-assembly mechanism of nanofibers, using a small peptide amphiphile (NapFFKYp) as a model. Combining experimental and simulation methods, we identify the self-assembly pathways in the solution and on the substrates, respectively. In the solution, peptide amphiphiles undergo the nucleation process to grow into nanofibers. The nanofibers can further twist into high-ordered nanofibers with aging. On the substrates, peptide amphiphiles form nanofibers and nanosheet structures simultaneously. This surface-induced nanosheet consists of rod-like structures, and its thickness is substrate-dependent. Most intriguingly, water can transform the nanosheet into the nanofiber. Molecular dynamic simulation suggests that hydrophobic and ion-ion interactions are dominant forces during the self-assembly process.We report the investigation of the self-assembly mechanism of nanofibers, using a small peptide amphiphile (NapFFKYp) as a model. Combining experimental and simulation methods, we identify the self-assembly pathways in the solution and on the substrates, respectively. In the solution, peptide amphiphiles undergo the nucleation process to grow into nanofibers. The nanofibers can further twist into high-ordered nanofibers with aging. On the substrates, peptide amphiphiles form nanofibers and nanosheet structures simultaneously. This surface-induced nanosheet consists of rod-like structures, and its thickness is substrate-dependent. Most intriguingly, water can transform the nanosheet into the nanofiber. Molecular dynamic simulation suggests that hydrophobic and ion-ion interactions are dominant forces during the self-assembly process. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr04672j

  9. Sacrificial amphiphiles: Eco-friendly chemical herders as oil spill mitigation chemicals.

    Science.gov (United States)

    Gupta, Deeksha; Sarker, Bivas; Thadikaran, Keith; John, Vijay; Maldarelli, Charles; John, George

    2015-06-01

    Crude oil spills are a major threat to marine biota and the environment. When light crude oil spills on water, it forms a thin layer that is difficult to clean by any methods of oil spill response. Under these circumstances, a special type of amphiphile termed as "chemical herder" is sprayed onto the water surrounding the spilled oil. The amphiphile forms a monomolecular layer on the water surface, reducing the air-sea surface tension and causing the oil slick to retract into a thick mass that can be burnt in situ. The current best-known chemical herders are chemically stable and nonbiodegradable, and hence remain in the marine ecosystem for years. We architect an eco-friendly, sacrificial, and effective green herder derived from the plant-based small-molecule phytol, which is abundant in the marine environment, as an alternative to the current chemical herders. Phytol consists of a regularly branched chain of isoprene units that form the hydrophobe of the amphiphile; the chain is esterified to cationic groups to form the polar group. The ester linkage is proximal to an allyl bond in phytol, which facilitates the hydrolysis of the amphiphile after adsorption to the sea surface into the phytol hydrophobic tail, which along with the unhydrolyzed herder, remains on the surface to maintain herding action, and the cationic group, which dissolves into the water column. Eventual degradation of the phytol tail and dilution of the cation make these sacrificial amphiphiles eco-friendly. The herding behavior of phytol-based amphiphiles is evaluated as a function of time, temperature, and water salinity to examine their versatility under different conditions, ranging from ice-cold water to hot water. The green chemical herder retracted oil slicks by up to ~500, 700, and 2500% at 5°, 20°, and 35°C, respectively, during the first 10 min of the experiment, which is on a par with the current best chemical herders in practice. PMID:26601197

  10. Fusiogenic activity of natural amphiphiles, 5-n-alkylresorcinols in a yeast protoplast system.

    Science.gov (United States)

    Kozubek, A; Skała, J

    1995-01-01

    Two homologues of cereal grain resorcinolic lipids, 5-n-heptadecylresorcinol and 5-n-heptadecenylresorcinol studied in the system employing yeast cell protoplasts showed marked fusiogenic activity. The frequency of hybrid formation induced by studied amphiphiles was significantly higher than that obtained with the use of 40% (w/v) polyethylene glycol 4000. The resorcinolic lipids as fusion-inducing agents did not affect regeneration of the cellular wall. The fusiogenic activity of resorcinolic lipids lost when calcium ions were absent in the medium. Fusiogenic activity of studied amphiphiles is related to their ability to induce non-bilayer structures within the cellular membranes. PMID:8579682

  11. Synthesis of amphiphilic aminated inulin via 'click chemistry' and evaluation for its antibacterial activity.

    Science.gov (United States)

    Dong, Fang; Zhang, Jun; Yu, Chunwei; Li, Qing; Ren, Jianming; Wang, Gang; Gu, Guodong; Guo, Zhanyong

    2014-09-15

    Inulins are a group of abundant, water-soluble, renewable polysaccharides, which exhibit attractive bioactivities and natural properties. Improvement such as chemical modification of inulin is often performed prior to further utilization. We hereby presented a method to modify inulin at its primary hydroxyls to synthesize amphiphilic aminated inulin via 'click chemistry' to facilitate its chemical manipulation. Additionally, its antibacterial property against Staphylococcus aureus (S. aureus) was also evaluated and the best inhibitory index against S. aureus was 58% at 1mg/mL. As the amphiphilic aminated inulin is easy to prepare and exhibits improved bioactivity, this material may represent as an attractive new platform for chemical modifications of inulin.

  12. Robust conductance of dumbbell molecular junctions with fullerene anchoring groups

    DEFF Research Database (Denmark)

    Markussen, Troels; Settnes, Mikkel; Thygesen, Kristian Sommer

    2011-01-01

    The conductance of a molecular wire connected to metallic electrodes is known to be sensitive to the atomic structure of the molecule-metal contact. This contact is to a large extent determined by the anchoring group linking the molecular wire to the metal. It has been found experimentally...... that a dumbbell construction with C60 molecules acting as anchors yields more well-defined conductances as compared to the widely used thiol anchoring groups. Here, we use density functional theory to investigate the electronic properties of this dumbbell construction. The conductance is found to be stable...... support the original motivation to achieve conductance values more stable towards changes in the structure of the molecule-metal contact leading to larger reproducibility in experiments. © 2011 American Institute of Physics....

  13. Optical Fiber Grating Sensor for Force Measurement of Anchor Cable

    Institute of Scientific and Technical Information of China (English)

    JIANG Desheng; FU Jinghua; LIU Shengchun; SUI Lingfeng; FU Rong

    2006-01-01

    The development of the sensor suitable for measuring large load stress to the anchor cable becomes an important task in bridge construction and maintenance. Therefore, a new type of optical fiber sensor was developed in the laboratory - optical fiber grating sensor for force measurement of anchor cable (OFBFMAC). No similar report about this kind of sensor has been found up to now in China and other countries. This sensor is proved to be an effective way of monitoring in processes of anchor cable installation, cable cutting, cable force regulation, etc, with the accurate and repeatable measuring results. Its successful application in the tie bar cable force safety monitoring for Wuhan Qingchuan bridge is a new exploration of optical fiber grating sensing technology in bridge tie bar monitoring system.

  14. Controlling molecular ordering in solution-state conjugated polymers.

    Science.gov (United States)

    Zhu, J; Han, Y; Kumar, R; He, Y; Hong, K; Bonnesen, P V; Sumpter, B G; Smith, S C; Smith, G S; Ivanov, I N; Do, C

    2015-10-01

    Rationally encoding molecular interactions that can control the assembly structure and functional expression in a solution of conjugated polymers hold great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with the desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.

  15. Experience-based, body-anchored qualitative research interviewing

    DEFF Research Database (Denmark)

    Stelter, Reinhard

    2010-01-01

    Two theoretical constructs that lay the foundation for experience-based, body-anchored interviewing are presented: the first-person perspective and the concept of meaning. These theoretical concepts are concretized, first, by means of a methodological framework for experience-based, body......-anchored interviewing, and second, by an interview guide that explores a research participant's personal experience with mindfulness meditation. An excerpt from an interview is discussed to illustrate the advantages of this interview form, namely its value as a methodological instrument for qualitative research...... in areas such as traditional and holistic medicine, Western alternative and complementary medicine, nursing, psychotherapy, coaching, physiotherapy, movement arts, and physical education....

  16. Experience-based, body-anchored qualitative research interviewing.

    Science.gov (United States)

    Stelter, Reinhard

    2010-06-01

    Two theoretical constructs that lay the foundation for experience-based, body-anchored interviewing are presented: the first-person perspective and the concept of meaning. These theoretical concepts are concretized, first, by means of a methodological framework for experience-based, body-anchored interviewing, and second, by an interview guide that explores a research participant's personal experience with mindfulness meditation. An excerpt from an interview is discussed to illustrate the advantages of this interview form, namely its value as a methodological instrument for qualitative research in areas such as traditional and holistic medicine, Western alternative and complementary medicine, nursing, psychotherapy, coaching, physiotherapy, movement arts, and physical education.

  17. Addition of lipid substituents of mammalian protein glycosylphosphoinositol anchors.

    OpenAIRE

    Singh, N.; Zoeller, R A; Tykocinski, M. L.; Lazarow, P B; Tartakoff, A M

    1994-01-01

    A single metabolic path leading to synthesis of ether lipids is known in animal cells, the major products of which are plasmalogens. To learn whether this peroxisomal path is also responsible for the synthesis of base-resistant lipid components of glycosylphosphoinositol (GPI)-anchored membrane proteins, we have investigated the structure of anchor precursor mannolipids both in wild-type cells (CHO-K1 and a macrophage-like line, RAW 264.7) and in two corresponding mutant cells in which ether ...

  18. PULLOUT CAPACITY OF HORIZONTAL AND INCLINED PLATE ANCHORS IN CLAYEY SOILS

    Directory of Open Access Journals (Sweden)

    BALESHWAR SINGH

    2011-11-01

    Full Text Available Soil anchors are required to withstand uplift or lateral forces acting on the foundations of structures constructed both in land and offshore sites. Plate anchoring system is being increasingly used to moor floating structures for the exploration and development of oil and gas fields. In this study, various experimental,theoretical and numerical approaches for estimation of pullout capacity of horizontal and inclined plate anchors in clayey soils are reviewed. A comparative analysis of the ultimate capacity is then carried out for plate anchors embedded in clayey soils by varying embedment ratio for horizontal anchors and by varying inclination angle for inclined plate anchors.

  19. Arrangement of anchor reinforcement in roadway for fully mechanized sublevel caving

    Institute of Scientific and Technical Information of China (English)

    勾攀峰; 陈启永; 芦付松

    2003-01-01

    Bolting of mining roadway for fully mechanized sublevel caving has been practised successfully in Hebi mining area.It provides a new method for roadway support and settles the problem of support difficulty radically for sublevel caving in Hebi mining area.Where anchor reinforcement holds an important station in roadway support.This article brings forward the arrangement project of anchor based on theoretic analysis.Compared with arranged in the middle of the entry, anchor arranged in the vertex of the entry can reduces the length of anchor,shortens the anchor installation time,and heightens the reliability of anchor installation.

  20. Thermal conductivity of polymer composites with oriented boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Hong Jun; Eoh, Young Jun [Department of Materials Engineering, Kyonggi University, Suwon (Korea, Republic of); Park, Sung Dae [Electronic Materials and Device Research Center, Korea Electronics Technology Institute, Seongnam (Korea, Republic of); Kim, Eung Soo, E-mail: eskim@kyonggi.ac.kr [Department of Materials Engineering, Kyonggi University, Suwon (Korea, Republic of)

    2014-08-20

    Highlights: • Thermal conductivity depended on the orientation of BN in the polymer matrices. • Hexagonal boron nitride (BN) particles were treated by C{sub 27}H{sub 27}N{sub 3}O{sub 2} and C{sub 14}H{sub 6}O{sub 8}. • Amphiphilic-agent-treated BN particles are more easily oriented in the composite. • BN/PVA composites with C{sub 14}H{sub 6}O{sub 8}-treated BN showed the highest thermal conductivity. • Thermal conductivity of the composites was compared with several theoretical models. - Abstract: Thermal conductivity of boron nitride (BN) with polyvinyl alcohol (PVA) and/or polyvinyl butyral (PVB) was investigated as a function of the degree of BN orientation, the numbers of hydroxyl groups in the polymer matrices and the amphiphilic agents used. The composites with in-plane orientation of BN showed a higher thermal conductivity than the composites with out-of-plane orientation of BN due to the increase of thermal pathway. For a given BN content, the composites with in-plane orientation of BN/PVA showed higher thermal conductivity than the composites with in-plane orientation of BN/PVB. This result could be attributed to the improved degree of orientation of BN, caused by a larger number of hydroxyl groups being present. Those treated with C{sub 14}H{sub 6}O{sub 8} amphiphilic agent demonstrated a higher thermal conductivity than those treated by C{sub 27}H{sub 27}N{sub 3}O{sub 2}. The measured thermal conductivity of the composites was compared with that predicted by the several theoretical models.

  1. Thermal conductivity of polymer composites with oriented boron nitride

    International Nuclear Information System (INIS)

    Highlights: • Thermal conductivity depended on the orientation of BN in the polymer matrices. • Hexagonal boron nitride (BN) particles were treated by C27H27N3O2 and C14H6O8. • Amphiphilic-agent-treated BN particles are more easily oriented in the composite. • BN/PVA composites with C14H6O8-treated BN showed the highest thermal conductivity. • Thermal conductivity of the composites was compared with several theoretical models. - Abstract: Thermal conductivity of boron nitride (BN) with polyvinyl alcohol (PVA) and/or polyvinyl butyral (PVB) was investigated as a function of the degree of BN orientation, the numbers of hydroxyl groups in the polymer matrices and the amphiphilic agents used. The composites with in-plane orientation of BN showed a higher thermal conductivity than the composites with out-of-plane orientation of BN due to the increase of thermal pathway. For a given BN content, the composites with in-plane orientation of BN/PVA showed higher thermal conductivity than the composites with in-plane orientation of BN/PVB. This result could be attributed to the improved degree of orientation of BN, caused by a larger number of hydroxyl groups being present. Those treated with C14H6O8 amphiphilic agent demonstrated a higher thermal conductivity than those treated by C27H27N3O2. The measured thermal conductivity of the composites was compared with that predicted by the several theoretical models

  2. Process for depositing strong adherend polymer coating onto an electrically conductive surface

    OpenAIRE

    Bertrand, Olivier; Jérôme, Robert; Gautier, Sandrine; Maquet, Véronique; Detrembleur, Christophe; Jérôme, Christine; Voccia, Samuel; Claes, Michaël; Lou, Xudong; Labaye, David-Emmanuel

    2002-01-01

    Process for depositing by electrografting a strong adherent polymer coating onto an electrically conductive surface comprising an electrochemical grafting at the surface of an active monomer for forming a primer coating P onto said surface and having as general formula: X0 (meth)acrylate wherein X is either part of a preformed polymer or is an intermediate agent for polyaddition reaction or is an anchoring group for attachment of a molecule having at least one complementary reactive group. Su...

  3. Removal and recovery of toxic metal ions from aqueous waste sites using polymer pendant ligands

    Energy Technology Data Exchange (ETDEWEB)

    Fish, D. [Lawrence Berkeley National Lab., CA (United States)

    1996-10-01

    The purpose of this project is to investigate the use of polymer pendant ligand technology to remove and recover toxic metal ions from DOE aqueous waste sites. Polymer pendant lgiands are organic ligands, anchored to crosslinked, modified divinylbenzene-polystyrene beads, that can selectively complex metal ions. The metal ion removal step usually occurs through a complexation or ion exchange phenomena, thus recovery of the metal ions and reuse of the beads is readily accomplished.

  4. Current status of frameless anchored IUD for immediate intracesarean insertion.

    Science.gov (United States)

    Wildemeersch, Dirk; Goldstuck, Norman D; Hasskamp, Thomas

    2016-01-01

    Immediate postpartum intrauterine device (IUD) insertion deserves great attention as it can provide immediate, timely and convenient contraception plus the added benefit of preventing repeat unintended pregnancies. Although women post vaginal delivery can benefit from immediate post-placenta contraception, women undergoing Cesarean section clearly need contraception, as an inter-delivery interval shorter than 18 months places them at a high risk for uterine rupture. The main drawback of currently available framed IUD devices for immediate postpartum insertion of an IUD is their high expulsion and displacement rates when inserted immediately postpartum after both vaginal and Cesarean delivery. Current research suggests that a brief window of opportunity exists of 10 minutes for insertion of conventional IUDs after which time expulsion rates both immediately and over time are greatly enhanced. This paper summarizes the current research conducted to overcome the expulsion problems associated with conventional T-shaped devices as well as through the use of an anchored frameless device. In the 1970s and 1980s, attempts were made to solve the expulsion problem by modifying existing devices, such as adding absorbable sutures (Delta-T) or additional appendages. These attempts proved to be clinically unsuccessful as the catgut suture added to the transverse arms did not provide sufficient resistance to prevent downward displacement and expulsion. An anchoring technique to suspend a copper IUD to the fundus of the uterus was developed in Belgium in the 1980s and has been the subject of extensive ongoing clinical research since 1985. Recently the frameless copper releasing anchor IUD, GyneFix, has been tested for postplacental insertion. Initially, the anchor was modified by the inclusion of a biodegradable cone which was added below the anchoring knot. Clinical studies confirmed the adequacy of this approach suggesting that it was technically possible to anchor an IUD

  5. Star polymer unimicelles on graphene oxide flakes.

    Science.gov (United States)

    Choi, Ikjun; Kulkarni, Dhaval D; Xu, Weinan; Tsitsilianis, Constantinos; Tsukruk, Vladimir V

    2013-08-01

    We report the interfacial assembly of amphiphilic heteroarm star copolymers (PSnP2VPn and PSn(P2VP-b-PtBA)n (n = 28 arms)) on graphene oxide flakes at the air-water interface. Adsorption, spreading, and ordering of star polymer micelles on the surface of the basal plane and edge of monolayer graphene oxide sheets were investigated on a Langmuir trough. This interface-mediated assembly resulted in micelle-decorated graphene oxide sheets with uniform spacing and organized morphology. We found that the surface activity of solvated graphene oxide sheets enables star polymer surfactants to subsequently adsorb on the presuspended graphene oxide sheets, thereby producing a bilayer complex. The positively charged heterocyclic pyridine-containing star polymers exhibited strong affinity onto the basal plane and edge of graphene oxide, leading to a well-organized and long-range ordered discrete micelle assembly. The preferred binding can be related to the increased conformational entropy due to the reduction of interarm repulsion. The extent of coverage was tuned by controlling assembly parameters such as concentration and solvent polarity. The polymer micelles on the basal plane remained incompressible under lateral compression in contrast to ones on the water surface due to strongly repulsive confined arms on the polar surface of graphene oxide and a preventive barrier in the form of the sheet edges. The densely packed biphasic tile-like morphology was evident, suggesting the high interfacial stability and mechanically stiff nature of graphene oxide sheets decorated with star polymer micelles. This noncovalent assembly represents a facile route for the control and fabrication of graphene oxide-inclusive ultrathin hybrid films applicable for layered nanocomposites.

  6. SELF-ASSEMBLING AMPHIPHILIC POLYELECTROLYTES AND THEIR NANOSTRUCTURES

    Institute of Scientific and Technical Information of China (English)

    Yotaro Morishima

    2000-01-01

    The self-assembling behavior of random copolymers of sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS)and hydrophobic comonomers possessing dodecyl groups linked by various spacer bonds was discussed with a focus on the effect of the spacer. The characterization of association behavior of such polymers in water using quasielastic light scattering,capillary electrophoresis, NMR relaxation, various fluorescence, and viscoelastic methods was described. These copolymers form a variety of self-assembled nanostructures depending on the type of the spacer. Random copolymers of AMPS and Ndodecylmethacrylamide show a strong preference for intrapolymer self-association even in concentrated aqueous solutions forming single-macromolecular self-assemblies (unimolecular micelles). In contrast, random copolymers of AMPS and dodecyl methacrylate are prone to undergo interpolymer associations yielding multipolymer micelles. In random copolymers of AMPS and a methacrylate substituted a nonionic surfactant (HO(CH2CH2O)25C12H25) (C12E25), dodecyl groups are much less restricted by the polymer backbone because they are linked via a long, flexible hydrophilic spacer. Thus, the polymerbound C12E25 surfactant moieties form micelles similar to those formed by discrete surfactants, but they are bridged by polymer chains forming a network structure.

  7. [Dactylogyrids (Monogenea: Dactylogyridea) with an unusual number of anchors, their origin and phylogenetic significance. Reference data].

    Science.gov (United States)

    Gerasev, P I

    2002-01-01

    It is considered that in Anacanthorinae, Markewitschiana and Pseudacolpenteron pavlovskii (Dactylogyridae s. s.) the anchors are absent originally. In the other dactylogyrids (s. l.) without anchors (Pseudacolpenteron ignotus; Acolpenteron; Anonchohaptor-Icelanchohaptor; Kritskyia-Telethecium-Pavanelliela) these structures are lost. In related genera Rhinoxenus and Nanotrema the dorsal pair of anchors is transformed into the "spikes"; in Heteronchocleidinae there is one anchor; in Trinigyrus and Schilbetrematoides are two anchors; and in Urogyrus three anchors are reduced. But in Rhinonaster, Cacatyocotyle, Callceostomella, Neocalseostoma elongatum and Pseudodactylogyridae the presence of one pair of ventral "peduncular" or "haptoral" anchors appear to be the original state. For Anacanthorinae and Dactylogyridae s. s. the presence of 18-16 hooks, original lacking of anchors, appearance of one pair of them, evolutionary development and subsequent reduction of these structures are characteristic. In the dactylogyrids (s. l.) having two pairs of anchors and 14 hooks, one pair of the anchors is present originally, then usually the second dorsal pair grows up, and finally, the reduction of a part of anchors or all the anchors is possible. In the 16-hooked dactylogyrids (s. l.) having two pairs of anchors (Tetraonchinea, Amphibdellainea, Neodactylodiscinea) the original lacking or reduction of the anchors is not reported. The author considers, that it is unwarranted to unite all dactylogyrids (s. l.) without anchors into the superorder Ananchorea Malmberg, 1990 or to postulate the original presence of the two pairs of ventral anchors in this group. It is also impossible to unit all dactylogyrids (s. l.) having 0-4 anchors and 18-14 hooks into Dactylogyridae sensu Boeger et Kritsky, 1993. PMID:12070963

  8. Self-assembling peptide amphiphile nanostructures for cancer therapy

    Science.gov (United States)

    Soukasene, Stephen

    The application of nanotechnology to cancer therapy shows great promise for reducing the burden of the disease. By virtue of their size, nanoscale objects preferentially accumulate in tumor tissue through an enhanced permeability and retention (EPR) effect. However, to fully overcome the issues that limit current cancer treatments, viable nanostructures must also impart multifunctionality and be fully compatible with their biological surrounds. The self-assembling peptide amphiphile (PA) materials studied extensively in the Stupp Research Group form very biocompatible high aspect ratio nanostructures that meet these criteria. This thesis investigates the development of PA nanostructures designed to treat cancer. We first look to use the PA as a drug delivery vehicle by entrapping a small hydrophobic anti-cancer drug, camptothecin, in the core of the nanostructures. Using a solvent evaporation technique to load the drug into the PA nanofibers, we are able to improve the aqueous solubility of the molecule by nearly 30-fold. TEM and AFM studies show that entrapment of drug molecules does not disrupt the self-assembled morphology of the nanofiber. In vitro and in vivo studies are also conducted to demonstrate the bioactivity of the drug after its entrapment. As a potential platform for novel therapeutics, we next develop techniques for using light irradiation to trigger self-assembly inside the confined space of liposomes. We encapsulate PA monomers that assemble under acidic conditions along with a photoacid generator inside liposomes. Upon exposure to 254 nm light, the PA monomers self assemble inside the liposome to form nanostructures, which we observe through a quick freeze/deep etch technique that allows us to look inside the liposomes by SEM and TEM. Last of all, the development and discovery of epitopes for targeting PA nanostructures to tumors are explored. Using phage display technology we generate two groups of peptide sequences, one of which can potentially

  9. Resilient self-assembling hydrogels from block copolypeptide amphiphiles

    Science.gov (United States)

    Nowak, Andrew Paul

    The ability to produce well defined synthetic polypeptides has been greatly improved by the discovery of transition metal species that mediate the controlled polymerization of N-carboxyanhydrides (NCAs). These metal species create a living polymerization system by producing control over chain length, low polydispersities, and the ability to form complex block architectures. We have applied this system to the synthesis of block copolypeptide amphiphiles. Initial block copolymers synthesized were composed of hydrophilic, cationic poly(L-Lysine) combined with hydrophobic, alpha-helical poly(L-Leucine). These Lysine- block-Leucine copolypeptides were found to form stiff, clear hydrogels at low concentration (˜1 wt%) in low ionic strength water. Based on this unexpected result we used the flexibility of our transition metal polymerization chemistry to better understand the nature and mechanisms of gel formation in these materials. Systematic changes to the original Lysine-block-Leucine copolypeptides were made by altering overall chain size, relative block length, polyelectrolyte charge, and hydrophobic secondary structure. Rheological characterization revealed that the strength of these hydrogels was primarily dependent on degree of polymerization, relative block length, and a well ordered secondary structure in the hydrophobic segment. The Lysine-block-Leucine hydrogels were formed by direct addition of water to dry polypeptide material which swelled to homogeneously fill the entire volume of liquid with no special processing. CryoTEM showed a percolating cellular network at ˜100nm that appears to be comprised of both membranes and fibers. Larger length scales studied with Laser Scanning Confocal Microscopy revealed a spontaneously formed microporous network with large (˜10mum) water rich voids. These hydrogels also displayed interesting mechanical properties including rapid recovery of solid like behavior after being sheared to a liquid and mechanical stability

  10. Self-Assembling Peptide Amphiphiles for Targeted Drug Delivery

    Science.gov (United States)

    Moyer, Tyson

    The systemic delivery of therapeutics is currently limited by off-target side effects and poor drug uptake into the cells that need to be treated. One way to circumvent these issues is to target the delivery and release of therapeutics to the desired location while limiting systemic toxicity. Using self-assembling peptide amphiphiles (PAs), this work has investigated supramolecular nanostructures for the development of targeted therapies. Specifically, the research has focused on the interrelationships between presentation of targeting moeities and the control of nanostructure morphology in the context of systemic delivery for targeting cancer and vascular injuries. The self-assembly region of the PA was systematically altered to achieve control of nanostructure widths, from 100 nm to 10 nm, by the addition of valine-glutamic acid dimers into the chemical structure, subsequently increasing the degree of nanostructure twist. For the targeting of tumors, a homing PA was synthesized to include a dimeric, cyclic peptide sequence known to target the cancer-specific, death receptor 5 (DR5) and initiate apoptosis through the oligomerization of DR5. This PA presented a multivalent display of DR5-binding peptides, resulting in improved binding affinity measured by surface plasmon resonance. The DR5-targeting PA also showed enhanced efficacy in both in vitro and in vivo tumor models relative to non-targeted controls. Alternative modifications to the PA-based antitumor therapies included the use of a cytotoxic, membrane-lytic PA coassembled with a pegylated PA, which showed enhanced biodistribution and in vivo activity after coassembly. The functionalization of the hydrophobic core was also accomplished through the encapsulation of the chemotherapy camptothecin, which was shown to be an effective treatment in vivo. Additionally, a targeted PA nanostructure was designed to bind to the site of vascular intervention by targeting collagen IV. Following balloon angioplasty

  11. SNP Discovery and Chromosome Anchoring Provide the First Physically-Anchored Hexaploid Oat Map and Reveal Synteny with Model Species.

    OpenAIRE

    Rebekah E Oliver; Tinker, Nicholas A.; Lazo, Gerard R.; Shiaoman Chao; Jellen, Eric N.; Martin L. Carson; Rines, Howard W; Donald E Obert; Lutz, Joseph D.; Irene Shackelford; Korol, Abraham B.; Charlene P. Wight; Gardner, Kyle M.; Jiro Hattori; Beattie, Aaron D

    2013-01-01

    A physically anchored consensus map is foundational to modern genomics research; however, construction of such a map in oat (Avena sativa L., 2n = 6x = 42) has been hindered by the size and complexity of the genome, the scarcity of robust molecular markers, and the lack of aneuploid stocks. Resources developed in this study include a modified SNP discovery method for complex genomes, a diverse set of oat SNP markers, and a novel chromosome-deficient SNP anchoring strategy. These resources wer...

  12. Tuning the sphere-to-rod transition in the self-assembly of thermoresponsive polymer hybrids.

    Science.gov (United States)

    Lee, Jangwook; Park, Honghyun; Jeong, Eun Ju; Kwark, Young-Je; Lee, Kuen Yong

    2015-12-01

    Nano-scale drug delivery systems have undergone extensive development, and control of size and structure is critical for regulation of their biological responses and therapeutic efficacy. Amphiphilic polymers that form self-assembled structures in aqueous media have been investigated and used for the diagnosis and therapy of various diseases, including cancer. Here, we report the design and fabrication of thermoresponsive polymeric micelles from alginate conjugated with poly(N-isopropylacrylamide) (PNIPAAm). Alginate-PNIPAAm hybrids formed self-aggregated structures in response to temperature changes near body temperature. A structural transition from micellar spheres to rods of alginate-PNIPAAm hybrids was observed depending on the molecular weight of PNIPAAm and the polymer concentration. Additionally, hydrogels with nanofibrous structures were formed by simply increasing the polymer concentration. This approach to controlling the structure of polymer micelles from nanoparticles to fibrous hydrogels may be useful in applications in drug delivery and tissue engineering.

  13. Dissipative Particle Dynamics Study on Aggregation of MPEG- PAE-PLA Block Polymer Micelles Loading Doxorubicine

    Institute of Scientific and Technical Information of China (English)

    杨楚芬; 孙尧; 章莉娟; 朱国典; 张灿阳; 钱宇

    2012-01-01

    To guide the molecular design of the pH-sensitive triblock amphiphilic polymer MPEG-PAE-PLA and the for- mula design of its doxorubicine (DOX)-loaded micelles, dissipative particle dynamics (DPD) simulations are em- ployed to investigate the aggregation behaviors of the DOX-loaded micelles. The simulation results showed that the aggregate morphologies of micelles and DOX distribution are influenced by degree of polymerization of blocks, and the proposed structure of polymer is MPEG44-PAE3-PLA4. With different contents of polymer or DOX, differ- ent aggregate morphologies of the micelles, like microsphere, spindle/column, reticulation or lamella are observed. To prepare the micro-spherical DOX-loaded micelles, the polymer content is proposed as 10%--15%, and the DOX content less than 10%.

  14. Cloud point, fluorimetric and 1H NMR studies of ibuprofen-polymer systems

    Science.gov (United States)

    Khan, Iqrar Ahmad; Anjum, Kahkashan; Koya, P. Ajmal; Qadeer, Atiytul; Kabir-ud-Din

    2014-01-01

    Influence of six polymers viz. hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP), sodium carboxy methyl cellulose (NaCMC) and dextran sulfate (DxS) on solution properties of amphiphilic drug ibuprofen (IBF) has been described in this work. As only HPMC showed the clouding behavior (among the polymers employed herein), its cloud point (CP) was studied in detail in presence of varying amounts of IBF containing different fixed concentrations of inorganic salts (NaCl, NaNO3, Na2SO4, KBr and KNO3). Presence of all these salts had CP reducing effect. By means of steady state fluorescence quenching studies, average aggregation number of IBF aggregates (Nagg) in the presence of varying amounts of the mentioned polymers were evaluated and discussed. 1H NMR studies show that the magnitude of chemical shifts (δ) varies with the nature of the polymer.

  15. Phosphorylcholine substituted polyolefins: New syntheses, solution assemblies, and polymer vesicles

    Science.gov (United States)

    Kratz, Katrina A.

    This thesis describes the synthesis and applications of a new series of amphiphilic homopolymers and copolymers consisting of hydrophobic polyolefin backbone and hydrophilic phosphorylcholine (PC) pendant groups. These polymers are synthesized by ring opening metathesis polymerization (ROMP) of a novel PC- cyclooctene monomer, and copolymerization of various functionalized cyclooctene comonomers. Incorporation of different comonomers into the PC-polyolefin backbone affords copolymers with different functionalities, including crosslinkers, fluorophores, and other reactive groups, that tune the range of applications of these polymers, and their hydrophobic/hydrophilic balance. The amphiphilic nature of PC-polyolefins was exploited in oil-water interfacial assembly, providing robust polymer capsules to encapsulate and deliver nanoparticles to damaged regions of a substrate in a project termed `repair-and-go.' In repair-and-go, a flexible microcapsule filled with a solution of nanoparticles probes an imperfection-riddled substrate as it rolls over the surface. The thin capsule wall allows the nanoparticles to escape the capsules and enter into the cracks, driven in part by favorable interactions between the nanoparticle ligands and the cracked surface (i.e., hydrophobic-hydrophobic interactions). The capsules then continue their transport along the surface, filling more cracks and depositing particles into them. The amphiphilic nature of PC-polyolefins was also exploited in aqueous assembly, forming novel polymer vesicles in water. PC-polyolefin vesicles ranged in size from 50 nm to 30 µm. The mechanical properties of PC-polyolefin vesicles were measured by micropipette aspiration techniques, and found to be more robust than conventional liposomes or polymersomes prepared from block copolymers. PC-polyolefin vesicles have potential use in drug delivery; it was found that the cancer drug doxorubicin could be encapsulated efficiently in PC-polyolefin vesicles. In

  16. Engineering Polymer Informatics

    OpenAIRE

    Adams, Nico; Ryder, Jennifer; Jessop, David M; Corbett, Peter; Murray-Rust, Peter

    2007-01-01

    The poster describes a strategy of for the development of polymer informatics. In particular, the development of polymer markup language, a polymer ontology and natural language processing tools for polymer literature.

  17. Macroscale Janus polymer single crystal film and its wettability analysis

    Science.gov (United States)

    Qi, Hao; Wang, Wenda; Zhou, Tian; Li, Christopher

    2014-03-01

    Liquid-liquid interface between two immiscible solvents is crucial to studying amphiphile and colloidal self-assembly. It can also guide chain folding during the crystallization process. In this presentation, we show that crystallization of dicarboxy end functionalized poly(ɛ-caprolactone) at water/pentyl acetate interface result in millimeter scale, uniform polymer single crystal (PSC) film. Due to the asymmetric nature at the liquid-liquid interface, the PSC film exhibit Janus property - a hydrophobic side and a hydrophilic side, which is confirmed by in-situ nano-condensation experiment using an environmental scanning electron microscope. The thickness of the PSC film changes with different polymer solution concentration, revealing a surface tension dominated crystallization process.

  18. Antimocrobial Polymer

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, William F. (Utica, OH); Huang, Zhi-Heng (Walnut Creek, CA); Wright, Stacy C. (Columbus, GA)

    2005-09-06

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from quaternary ammonium compounds, gentian violet compounds, substituted or unsubstituted phenols, biguanide compounds, iodine compounds, and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A)3P wherein A is hydroxyalkyl; and the antimicrobial agent is chlorhexidine, dimethylchlorophenol, cetyl pyridinium chloride, gentian violet, triclosan, thymol, iodine, and mixtures thereof.

  19. Antimicrobial Polymer

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, William F. (Utica, OH); Wright, Stacy C. (Flint, MI); Taylor, Andrew C. (Ann Arbor, MI)

    2004-09-28

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The polymeric composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from metals, metal alloys, metal salts, metal complexes and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one example embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl; and the metallic antimicrobial agent is selected from chelated silver ions, silver metal, chelated copper ions, copper metal, chelated zinc ions, zinc metal and mixtures thereof.

  20. The encapsulation of an amphiphile into polystyrene microspheres of narrow size distribution

    Directory of Open Access Journals (Sweden)

    Pellach Michal

    2011-12-01

    Full Text Available Abstract Encapsulation of compounds into nano- or microsized organic particles of narrow size distribution is of increasing importance in fields of advanced imaging and diagnostic techniques and drug delivery systems. The main technology currently used for encapsulation of molecules within uniform template particles while retaining their size distribution is based on particle swelling methodology, involving penetration of emulsion droplets into the particles. The swelling method, however, is efficient for encapsulation only of hydrophobic compounds within hydrophobic template particles. In order to be encapsulated, the molecules must favor the hydrophobic phase of an organic/aqueous biphasic system, which is not easily achieved for molecules of amphiphilic character. The following work overcomes this difficulty by presenting a new method for encapsulation of amphiphilic molecules within uniform hydrophobic particles. We use hydrogen bonding of acid and base, combined with a pseudo salting out effect, for the entrapment of the amphiphile in the organic phase of a biphasic system. Following the entrapment in the organic phase, we demonstrated, using fluorescein and (antibiotic tetracycline as model molecules, that the swelling method usually used only for hydrophobes can be expanded and applied to amphiphilic molecules.

  1. Bilayer Vesicles of Amphiphilic Cyclodextrins: Host Membranes That Recognize Guest Molecules

    NARCIS (Netherlands)

    Falvey, Patrick; Lim, Choon Woo; Darcy, Raphael; Revermann, Tobias; Karst, Uwe; Giesbers, Marcel; Marcelis, Antonius T.M.; Lazar, Adina; Coleman, Anthony W.; Reinhoudt, David N.; Ravoo, Bart Jan

    2005-01-01

    A family of amphiphilic cyclodextrins (6, 7) has been prepared through 6-S-alkylation (alkyl=n-dodecyl and n-hexadecyl) of the primary side and 2-O-PEGylation of the secondary side of a-, B-, and Y-cyclodextrins (PEG=poly(ethylene glycol)). These cyclodextrins form nonionic bilayer vesicles in aqueo

  2. New carbon-carbon linked amphiphilic carboranyl-porphyrins as boron neutron capture agents

    International Nuclear Information System (INIS)

    Novel amphiphilic carboranyl-porphyrins have been synthesized for Boron Neutron Capture Therapy (BNCT). These compounds have carbon-carbon bonds between the carborane residues and the porphyrin meso-phenyl groups, and contain 28-31% boron by weight . (author)

  3. Preparation of Vesicles and Nanoparticles of Amphiphilic Cyclodextrins Containing Labile Disulfide Bonds

    NARCIS (Netherlands)

    Nolan, Darren; Darcy, Raphael; Ravoo, Bart Jan

    2003-01-01

    Amphiphilic cyclodextrin derivatives were prepared in which a disulfide bond connects the hydrophobic substituents to the macrocycle. These compounds were obtained by 1,3-dicyclohexylcarbodiimide-mediated coupling reactions of heptakis(6-amino-6-deoxy)-B-cyclodextrins and disulfide-containing carbox

  4. Synthesis of Novel Amphiphilic Azobenzenes and X-ray Scattering Studies of Their Langmuir Monolayers

    DEFF Research Database (Denmark)

    Sørensen, Thomas Just; Kjær, Kristian; Breiby, Dag Werner;

    2008-01-01

    air-water interface, the amphiphilic azobenzenes form noncrystalline but stable Langmuir films that display an unusual reversible monolayer collapse close to 35 mN/m. The structures and phase transitions were studied by X-ray reflectivity (XR) and grazing-incidence X-ray diffraction, both utilizing...

  5. Gold Nanoparticles Protected with Thiol-Derivatized Amphiphilic Poly(epsilon-caprolactone)-b-poly(acrylic acid)

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Hvilsted, Søren

    2009-01-01

    Amphiphilic poly(epsilon-caprolactone)-b-poly(acrylic acid) (HS-PCL-b-PAA) with a thiol functionality in the PCL terminal has been prepared in a novel synthetic cascade. Initially, living anionic ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) employing the difunctional...

  6. Tunable Hydrophobicity in DNA Micelles : Design, Synthesis, and Characterization of a New Family of DNA Amphiphiles

    NARCIS (Netherlands)

    Anaya, Milena; Kwak, Minseok; Musser, Andrew J.; Muellen, Klaus; Herrmann, Andreas; Müllen, Klaus

    2010-01-01

    This work describes the synthesis and characterization of a new family of DNA amphiphiles containing modified nucleobases. The hydrophobicity was imparted by the introduction of a dodec-1-yne chain at the 5-position of the uracil base, which allowed precise and simple tuning of the hydrophobic prope

  7. Self-assembly of block copolymer-based ionic supramolecules based upon multi-tail amphiphiles

    DEFF Research Database (Denmark)

    Asad Ayoubi, M.; Almdal, Kristoffer; Zhu, K.;

    2015-01-01

    Utilising simple acid-base titration chemistry, a new family of Linear-b-Amphiphilic Comb (L-b-AC) ionic supramolecules [Soft Matter 2013, 9, 1540-1555] featuring multi-tail side-chains have been synthesized and examined by synchrotron SAXS. To three different parent diblock copolymers of poly(st...

  8. Inducing spin crossover in metallo-supramolecular polyelectrolytes through an amphiphilic phase transition.

    Science.gov (United States)

    Bodenthin, Yves; Pietsch, Ullrich; Möhwald, Helmuth; Kurth, Dirk G

    2005-03-01

    A phase transition in an amphiphilic mesophase is explored to deliberately induce mechanical strain in an assembly of tightly coupled metal ion coordination centers. Melting of the alkyl chains in the amphiphilic mesophase causes distortion of the coordination geometry around the central transition metal ion. As a result, the crystal field splitting of the d-orbital subsets decreases resulting in a spin transition from a low-spin to a high-spin state. The diamagnetic-paramagnetic transition is reversible. This concept is demonstrated in a metallo-supramolecular coordination polyelectrolyte-amphiphile complex self-assembled from ditopic bis-terpyridines, Fe(II) as central transition metal, and dialkyl phosphates as amphiphiles. The magnetic properties are studied in a Langmuir-Blodgett multilayer. The modularity of this concept provides extensive control of structure and function from molecular to macroscopic length scales and gives access to a wide range of new molecular magnetic architectures such as nanostructures, thin films, and liquid crystals. PMID:15740150

  9. Transfection of small numbers of human endothelial cells by electroporation and synthetic amphiphiles

    NARCIS (Netherlands)

    van Leeuwen, E B; van der Veen, A Y; Hoekstra, D; Engberts, J B; Halie, M R; van der Meer, J; Ruiters, M H

    1999-01-01

    OBJECTIVES: This study compared the efficiency of electroporation and synthetic amphiphiles. (SAINT-2pp/DOPE) in transfecting small numbers of human endothelial cells. METHODS AND RESULTS: Optimal transfection conditions were tested and appeared to be 400 V and 960 microF for electroporation and a 1

  10. Oxidized potato starch based thermoplastic films : Effect of combination of hydrophilic and amphiphilic plasticizers

    NARCIS (Netherlands)

    Niazi, Muhammad Bilal Khan; Broekhuis, Antonius A.

    2016-01-01

    Different combinations of hydrophilic (glycerol and water) and amphiphilic (isoleucine) plasticizers were studied in the production of thermoplastic starch (TPS) powders and films from oxidized potato starch. All powder samples had an irregular and shrivelled morphology. In all mixtures containing i

  11. Bilayer vesicles of amphiphilic cyclodextrines: host membranes that recognize guest molecules

    NARCIS (Netherlands)

    Falvey, P.; Lim, C.W.; Darcy, R.; Revermann, T.; Karst, U.; Marcelis, A.T.M.; Coleman, A.W.; Reinhoudt, D.N.; Ravoo, B.J.

    2005-01-01

    A family of amphiphilic cyclodextrins (6, 7) has been prepared through 6-S-alkylation (alkyl=n-dodecyl and n-hexadecyl) of the primary side and 2-O-PEGylation of the secondary side of alpha-, beta-, and gamma-cyclodextrins (PEG=poly(ethylene glycol)). These cyclodextrins form nonionic bilayer vesicl

  12. SYNTHESIS OF AMPHIPHILIC COMB-SHAPED COPOLYMERS USED FOR SURFACE MODIFICATION OF PVDF MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    Jian-hua Li; You-yi Xu; Jian-hua Wang; Chun-hui Du

    2009-01-01

    The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4-hydroxyphenyl) maleimide) (SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate (PEGMA) side groups was achieved by atom transfer radical polymerization (ATRP). The amphiphilic copolymers were characterized by ~1H-NMR, Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). From thermogravimetric analysis (TGA), the decomposition temperature of SHMI-g-PEGMA is lower than that of SHMI, and the graft ratio of PEGMA in the SHMI is 18.6%. The experimental results of solubilities showed that SHMI, SHMI-Br and SHMI-g-PEGMA had excellent solubility in polar solvents, such as DMF, DMSO and NMP. SHMI-g-PEGMA had higher solubilities in H_2O and methanol, while lower solubility in CHCl_3 than SHMI and SHMI-Br. PVDF blend membranes were prepared via the standard immersion precipitation phase inversion process, using amphiphilic SHMI-g-PEGMA copolymer as additives. The morphology and hydrophilicity of the blend membrane surfaces were characterized by SEM and water contact angle. It is demonstrated that the blend membranes display enhanced hydrophilicity compared to unmodified PVDF membranes. Finally, the permeation and anti-fouling properties were investigated. The result shows that amphiphilic SHMI-g-PEGMA copolymer increases the permeatability and anti-fouling property of PVDF membranes greatly.

  13. Geological significance of stone anchors from Dwarka waters, Gujarat, India

    Digital Repository Service at National Institute of Oceanography (India)

    Iyer, S.D.; Vora, K.H.; Gaur, A.S.

    A number of underwater man-made stone structures have been noted, that may be the remains of an ancient jetty, as a large number of stone anchors have been recovered off Dwarka, Gujarat. The archaeological importance of these artefacts is postulated...

  14. Impact of Enhanced Anchored Instruction in Inclusive Math Classrooms

    Science.gov (United States)

    Bottge, Brian A.; Toland, Michael D.; Gassaway, Linda; Butler, Mark; Choo, Sam; Griffen, Ann Katherine; Ma, Xin

    2015-01-01

    The Common Core State Standards for Mathematics will place more pressure on special education and math teachers to raise the skill levels of all students, especially those with disabilities in math (MD). The purpose of this study was to assess the effects of enhanced anchored instruction (EAI) on students with and without MD in co-taught general…

  15. Almost Lie structures on an anchored Banach bundle

    CERN Document Server

    Cabau, Patrick

    2011-01-01

    Under appropriate assumptions, we generalize the concept of linear almost Poisson struc- tures, almost Lie algebroids, almost differentials in the framework of Banach anchored bundles and the relation between these objects. We then obtain an adapted formalism for mechanical systems which is illustrated by the evolutionary problem of the "Hilbert snake"

  16. Ten Anchor Points for Teaching Principles of Marketing

    Science.gov (United States)

    Tomkovick, Chuck

    2004-01-01

    Effective marketing instructors commonly share a love for their students, an affinity for the subject matter, and a devotion to continuous quality improvement. The purpose of this article is to highlight 10 anchor points for teaching Principles of Marketing, which are designed to better engage students in the learning process. These anchor…

  17. Fullerene-based Anchoring Groups for Molecular Electronics

    DEFF Research Database (Denmark)

    Martin, Christian A.; Ding, Dapeng; Sørensen, Jakob Kryger;

    2008-01-01

    We present results on a new fullerene-based anchoring group for molecular electronics. Using lithographic mechanically controllable break junctions in vacuum we have determined the conductance and stability of single-molecule junctions of 1,4-bis(fullero[c]pyrrolidin-1-yl)benzene. The compound can...

  18. Analytical Model for Hook Anchor Pull-out

    DEFF Research Database (Denmark)

    Brincker, Rune; Ulfkjær, J. P.; Adamsen, P.;

    A simple analytical model for the pull-out of a hook anchor is presented. The model is based on a simplified version of the fictitious crack model. It is assumed that the fracture process is the pull-off of a cone shaped concrete part, simplifying the problem by assuming pure rigid body motions...

  19. Analytical Model for Hook Anchor Pull-Out

    DEFF Research Database (Denmark)

    Brincker, Rune; Ulfkjær, J. P.; Adamsen, P.;

    1995-01-01

    A simple analytical model for the pull-out of a hook anchor is presented. The model is based on a simplified version of the fictitious crack model. It is assume that the fracture process is the pull-off of a cone shaped concrete part, simplifying the problem by assuming pure rigid body motions...

  20. A Proteomics Investigation of Anchored PKA-RI Signaling

    NARCIS (Netherlands)

    Kovanich, D.

    2013-01-01

    Compartmentalization of kinases and phosphatases plays an important role in the specificity of second messenger mediated signaling events. Localization of the cAMP-dependent protein kinase is mediated by interaction of its regulatory subunit (PKA-R) with the versatile family of A-kinase anchoring pr