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Sample records for amphiphilic hyperbranched fluoropolymers

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. THE AMPHIPHILIC MULTIARM COPOLYMERS BASED ON HYPERBRANCHED POLYESTER AND LYSINE: SYNTHESIS AND SELF-ASSEMBLY

    Institute of Scientific and Technical Information of China (English)

    Jing Wang; Yuan Yao; Bing Ji; Wei Huang; Yong-feng Zhou; De-yue Yan

    2011-01-01

    The amphiphilic multiarm copolymers were synthesized through the modification of commercially available hyperbranched polyesters (Boltom H40) with N-ε-carbobenzoxy-L-Lysine N-carboxyanhydride (ZLys-NCA). After being condensed with N-Boc-phenylalanine (Boc-NPhe) and deprotected the Boc-groups in trifluoroacetic acid (TFA), the original terminal hydroxyl groups were transformed into the amino groups and then initiated the ring-opening polymerization of ZLys-NCA. The hydrophilic poly(L-lysine) was grafted to the surface of Boltorn H40 successfully after the protecting benzyl groups were removed by the HBr solution in glacial acetic acid (33 wt%). The resulting multiarm copolymers were characterized by the 1H-NMR, GPC and FTIR. The arm length calculated by NMR and GPC analysis was about 3 and 13 lysine-units for H40-Phe-PLysl and H40-Phe-PLys2 respectively. Due to the amphiphilic molecular structure, they displayed ability to self-assemble into spherical micelles in aqueous solution with the average diameter in the range from 70 nm to 250 nm. The CMC of H40-Phe-PLysl and H40-Phe-PLys2 was 0.013 mg/mL and 0.028 mg/mL, respectively,indicating that H40-Phe-PLysl with shorter arm length is easier to self-assemble than H40-Phe-PLys2 with longer arm length.

  8. 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.

  9. Bioreducible unimolecular micelles based on amphiphilic multiarm hyperbranched copolymers for triggered drug release

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel type of bioreducible amphiphilic multiarm hyperbranched copolymer (H40-star-PLA-SS-PEG) based on Boltorn H40 core,poly(L-lactide) (PLA) inner-shell,and poly(ethylene glycol) (PEG) outer-shell with disulfide-linkages between the hydrophobic and hydrophilic moieties was developed as unimolecular micelles for controlled drug release triggered by reduction.The obtained H40-star-PLA-SS-PEG was characterized in detail by nuclear magnetic resonance (NMR),Fourier transform infrared (FTIR),gel permeation chromatography (GPC),differential scanning calorimeter (DSC),and thermal gravimetric analysis (TGA).Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses suggested that H40-star-PLA-SS-PEG formed stable unimolecular micelles in aqueous solution with an average diameter of 19 nm.Interestingly,these micelles aggregated into large particles rapidly in response to 10 mM dithiothreitol (DTT),most likely due to shedding of the hydrophilic PEG outer-shell through reductive cleavage of the disulfide bonds.As a hydrophobic anticancer model drug,doxorubicin (DOX) was encapsulated into these reductive unimolecular micelles.In vitro release studies revealed that under the reduction-stimulus,the detachment of PEG outer-shell in DOX-loaded micelles resulted in a rapid drug release.Flow cytometry and confocal laser scanning microscopy (CLSM) measurements indicated that these DOX-loaded micelles were easily internalized by living cells.Methyl tetrazolium (MTT) assay demonstrated a markedly enhanced drug efficacy of DOX-loaded H40-star-PLA-SS-PEG micelles as compared to free DOX.All of these results show that these bioreducible unimolecular micelles are promising carriers for the triggered intracellular delivery of hydrophobic anticancer drugs.

  10. Hyperbranched Polysiloxysilanes

    Institute of Scientific and Technical Information of China (English)

    Masa-aki Kakimoto

    2005-01-01

    @@ 1Introduction Hyperbranched polymers have been paid attention because of their unique structures. Especially, they have many terminals whose number is the same as that of repeating units as far as they are synthesized from AB2 type monomers. These characteristics of the hyperbranched polymers make them new functionalized polymers. Polysiloxanes have unique properties such as low Tg, high decomposition temperature, water repulsion, and good dielectric property. They are widely fabricated from liquid (oil) to solid (resin) by changing the extent of crosslinking. We have studied dendrimers and hyperbrached polymers possessing polysiloxane structure. These materials have the amphiphilic nature when they have amine functional group at the terminal position.

  11. Dissipative particle dynamics simulation study on self-assembly of amphiphilic hyperbranched multiarm copolymers with different degrees of branching.

    Science.gov (United States)

    Tan, Haina; Wang, Wei; Yu, Chunyang; Zhou, Yongfeng; Lu, Zhongyuan; Yan, Deyue

    2015-11-21

    Hyperbranched multiarm copolymers (HMCs) have shown great potential to be excellent precursors in self-assembly to form various supramolecular structures in all scales and dimensions in solution. However, theoretical studies on the self-assembly of HMCs, especially the self-assembly dynamics and mechanisms, have been greatly lagging behind the experimental progress. Herein, we investigate the effect of degree of branching (DB) on the self-assembly structures of HMCs by dissipative particle dynamics (DPD) simulation. Our simulation results demonstrate that the self-assembly morphologies of HMCs can be changed from spherical micelles, wormlike micelles, to vesicles with the increase of DBs, which are qualitatively consistent with the experimental observations. In addition, both the self-assembly mechanisms and the dynamic processes for the formation of these three aggregates have been systematically disclosed through the simulations. These self-assembly details are difficult to be shown by experiments and are very useful to fully understand the self-assembly behaviors of HMCs. PMID:26364696

  12. 手性两亲超支化嵌段共聚物PG-b-PBTQMO-b-PG的合成%Synthesis of chiral amphiphilic hyperbranched block copolymer PG-b-PBTQMO-b-PG

    Institute of Scientific and Technical Information of China (English)

    蒋伟伟; 李胜夏; 郭素珍; 胡志国

    2013-01-01

    以叠氮基修饰的超支化共聚物PG-b-PBAMO-b-PG和10,11-二氢化奎宁为原料,通过“click”化学反应合成了一种新型侧链含有奎宁的光学活性两亲超支化嵌段共聚物PG-b-PBTQMO-b-PG.用傅里叶转变红外光谱(FT-IR)和核磁共振氢谱(1HNMR)对产物结构和组成进行了表征,并利用圆二色谱法研究了手性共聚物的光学活性.%A new optically active amphiphilic hyperbranehed block copolymer bearing quinine pendants pol-yglyeerol-b-poly [3,3-bis(triazolyl-L-quinine) methyl oxetane]-b-polyglycerol (PG-b-PBTQMO-b-PG) was synthesized by" click" reaction of azido-modified polyglycerol-b-poly(3,3-bis(azidomethyl) oxetane)-b-polyglycerol (PG-b-PBAMO-b-PG) hyperbranched eopolymer and 10,11-didehydro quinine.The Fourier transform infrared spectrum(FT-IR) and 1H nuclear magnetic resonance spectroscopy(1HNMR)were used to confirm its structure and composition.Additionally,the solution properties of this chiral copolymer were stu-died by circular dichroism(CD) spectroscopy.

  13. New Phase Transfer Agent for Dye:Application for Hyperbranched Poly(ester-amine)

    Institute of Scientific and Technical Information of China (English)

    Teng QIU; Li Ming TANG; Xin Lin TUO; De Shan LIU

    2004-01-01

    Hydrophilic hyperbranched poly(ester-amine) (HPEA) synthesized from diethanolamine and methyl acrylate was used as phase transfer agent for the first time to transfer methyl orange (MO) from water into chloroform.This process was quantified by UV-Vis spectra.A possible mechanism was put forward based on the formation of amphiphilic aggregates.

  14. Overview of the Development of the Fluoropolymer Industry

    Directory of Open Access Journals (Sweden)

    Hongxiang Teng

    2012-05-01

    Full Text Available The present review briefly describes the development of the fluoropolymer industry in the past 70 years. Discussed are industrial fluoropolymers including polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidenefluoride, polyvinylfluoride, ETFE, ECTFE, FEP, PFA, THV, Teflon AF and Cytop. Nafion is included as a special functional fluoropolymer material. These industrial fluoropolymers are introduced in the order of their discovery or time of first production, included are their chemical structures, thermal properties, mechanical properties, electrical and electronic properties, optical properties, chemical resistance, oxidative stabilities, weather stabilities, processabilities and their general applications. The main manufacturing companies for the different types of fluoropolymer products are also mentioned.

  15. Synthesis of fluoropolymers in supercritical carbon dioxide

    International Nuclear Information System (INIS)

    Fluoropolymers are used in many technologically demanding applications because of their balance of high-performance properties. A significant impediment to the synthesis of variants of commercially available amorphous fluoropolymers is their general insolubility in most solvents except chlorofluorocarbons (CFCs). The environmental concerns about CFCs can be circumvented by preparing these technologically important materials in supercritical fluids. The homogeneous solution polymerization of highly fluorinated acrylic monomers can be achieved in supercritical carbon dioxide by using free radical methods. In addition, detailed decomposition rates and efficiency factors were measured for azobisisobutyronitrile in supercritical carbon dioxide and were compared to those obtained with conventional liquid solvents

  16. Hyperbranched urethane-acrylates

    Directory of Open Access Journals (Sweden)

    Tasić Srba

    2004-01-01

    Full Text Available The synthesis, characterization and UV-curing of hyperbranched urethaneacrylates (HB-UA were investigated in this study. They were evaluated as oli-gomers in model UV curable coatings. HB-UAs were synthesized by reaction of an aliphatic hyperbranched polyester of the second generation (HBRG2 and an isocyanate adduct, obtained by the reaction of isophoronediisocyana-te and different hydroxy alkyl acrylates. Their thermal properties and viscosities depend on the degree of modification of HBRG2 and the type of hydroxy alkyl acrylate used. The introduction of a flexible alkoxylated spacer between the HBP core and acrylate end groups reduces steric hindrance by moving the cross linkable acrylate groups away from the HBP core and increase its reactivity. Due to the presence of abstractable H-atoms in the α-position to the ether links, HB-UAs based on poly(ethylene oxide monoacrylate are very reactive and do not show oxygen inhibition. The obtained coatings combine a high cross linking density with flexible segments between the cross links, which results in a good compromise between hardness and flexibility and have the potential to be used in different UV-curing applications.

  17. Optoelectronic devices incorporating fluoropolymer compositions for protection

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xuming; Chum, Pak-Wing S.; Howard, Kevin E.; Lopez, Leonardo C.; Sumner, William C.; Wu, Shaofu

    2015-12-22

    The fluoropolymer compositions of the present invention generally incorporate ingredients comprising one or more fluoropolymers, an ultraviolet light protection component (hereinafter UV protection component), and optionally one or more additional ingredients if desired. The UV protection component includes a combination of at least one hindered tertiary amine (HTA) compound having a certain structure and a weight average molecular weight of at least 1000. This tertiary amine is used in combination with at least one organic, UV light absorbing compound (UVLA compound) having a weight average molecular weight greater than 500. When the HTA compound and the UVLA compound are selected according to principles of the present invention, the UV protection component provides fluoropolymer compositions with significantly improved weatherability characteristics for protecting underlying materials, features, structures, components, and/or the like. In particular, fluoropolymer compositions incorporating the UV protection component of the present invention have unexpectedly improved ability to resist blackening, coloration, or other de gradation that may be caused by UV exposure. As a consequence, devices protected by these compositions would be expected to have dramatically improved service life. The compositions have a wide range of uses but are particularly useful for forming protective layers in optoelectronic devices.

  18. Characteristics and durability of fluoropolymer thin films

    OpenAIRE

    Cheneler, David; Bowen, James; Evans, Stephen D.; Górzny, Marcin; Adams, Michael J; Ward, Michael C.L.

    2011-01-01

    The use of plasma-polymerised fluoropolymer (CFxOy) thin films in the manufacture of microelectromechanical systems (MEMS) devices is well-established, being employed in the passivation step of the deep reactive ion etching (DRIE) process, for example. This paper presents an investigation of the effect of exposure to organic and aqueous liquid media on plasma polymerised CFxOy thin films. Atomic force microscopy (AFM), scanning electron microscopy (SEM), ellipsometry, X-ray photoelectron spec...

  19. Hyperbranched: a universal conjugated polymer platform.

    Science.gov (United States)

    Tolosa, Juan; Kub, Chris; Bunz, Uwe H F

    2009-01-01

    Out on a limb: Sonogashira coupling of a suitable AB(2) monomer containing two iodine and one alkyne group forms a hyperbranched conjugated polymer that is studded with iodine end groups (see picture: I purple). These iodine groups are a perfect handle for convenient, efficient, and high-yielding post-functionalization to access hyperbranched, fluorescent poly(phenyleneethynylene)s. PMID:19373821

  20. A supramolecular Janus hyperbranched polymer and its photoresponsive self-assembly of vesicles with narrow size distribution.

    Science.gov (United States)

    Liu, Yong; Yu, Chunyang; Jin, Haibao; Jiang, Binbin; Zhu, Xinyuan; Zhou, Yongfeng; Lu, Zhongyuan; Yan, Deyue

    2013-03-27

    Herein, we report a novel Janus particle and supramolecular block copolymer consisting of two chemically distinct hyperbranched polymers, which is coined as Janus hyperbranched polymer. It is constructed by the noncovalent coupling between a hydrophobic hyperbranched poly(3-ethyl-3-oxetanemethanol) with an apex of an azobenzene (AZO) group and a hydrophilic hyperbranched polyglycerol with an apex of a β-cyclodextrin (CD) group through the specific AZO/CD host-guest interactions. Such an amphiphilic supramolecular polymer resembles a tree together with its root very well in the architecture and can further self-assemble into unilamellar bilayer vesicles with narrow size distribution, which disassembles reversibly under the irradiation of UV light due to the trans-to-cis isomerization of the AZO groups. In addition, the obtained vesicles could further aggregate into colloidal crystal-like close-packed arrays under freeze-drying conditions. The dynamics and mechanism for the self-assembly of vesicles as well as the bilayer structure have been disclosed by a dissipative particle dynamics simulation. PMID:23464832

  1. EFFECT OF IRRADIATION TEMPERATURE ON GENERAL EQUATION OF SOL FRACTION-DOSE RELATIONSHIP FOR FLUOROPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wanxi; XU Jun

    1992-01-01

    In this paper, the effect of irradiation temperature on sol fraction-dose relationship of fluoropolymers was studied. It was found that the increasing of irradiation temperature can result in the decreasing of β value of fluoropolymer , which increases the crosslinking probability of fluoropolymer. The relationship between crosslinking parameter β and irradiation temperature (Ti)of fluoropolymer is established as follows:β=2.2 × 10-3Tg +4×10-4 (Tg-Ti )+0.206.β values of some fluoropolymers calculated from the above expression are in agreement with the experimental values.

  2. Carboxylated Polyurethanes Containing Hyperbranched Polyester Soft Segments

    Directory of Open Access Journals (Sweden)

    Žigon, M.

    2006-09-01

    Full Text Available hyperbranched polyester soft segments (HB PU with functional carboxylic groups in order to enable the preparation of stable HB PU dispersions. Carboxylated hyperbranched polyurethanes were synthesized using a hyperbranched polyester based on 2,2-bis(methylolpropionic acid of the fourth pseudo-generation (Boltorn H40 and hexamethylene (HDI or isophorone diisocyanate (IPDI. The reactivity of hyperbranched polyester with HDI was lower than expected, possibly due to the presence of less reactive hydroxyl groups in the linear repeat units. A gel was formed at mole ratios rNCO/OH = 1:2 or 1:4. The synthesis of HB PU was performed with partly esterified hyperbranched polyester with lowered hydroxyl functionality. The carboxyl groups were incorporated in the HB PU backbone by reaction of residual hydroxyl groups with cis-1,2-cyclohexanedicarboxylic anhydride. HB PU aqueous dispersions were stable at least for two months, although their films were brittle. The tensile strength and Young's modulus of blends of linear and HB PU decreased with increasing content of HB PU whereas elongation at break remained nearly constant, which was explained in terms of looser chain packing due to more open tree-like hyperbranched structures.

  3. Hyperbranched polyglycerols at the biointerface

    Science.gov (United States)

    Moore, Eli; Thissen, Helmut; Voelcker, Nicolas H.

    2013-08-01

    The control over biointerfacial interactions is the key to a broad range of biomedical applications, ranging from implantable devices to drug delivery and nanomedicine. In many of these applications, coatings are required that reduce or prevent non-specific interactions with the biological environment, while at the same time presenting specific bioactive signals. Whilst surface coatings based on polymers such as poly(ethylene glycol) (PEG) have been used successfully, many limitations persist in regard to the biocompatibility, stability and functionality of state-of-the-art polymer coatings. Most of these limitations are related to the fact that, typically, linear polymers are used with associated limited chemical functionality. Here, we examine the development of hyperbranched polyglycerols (HPGs) as promising candidates for the replacement of traditional linear polymers, such as the chemically analogous PEG, for the control of biointerfacial interactions. HPGs are highly branched globular molecules that exhibit a high valency, allow easy access to a variety of functionalities and can present biologically active signals. In this review, a comprehensive overview is provided with respect to the history, synthetic strategies, modifications and applications of HPGs.

  4. 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

  5. RHEOLOGY OF CONCENTRATED SOLUTIONS OF HYPERBRANCHED POLYESTERS

    Science.gov (United States)

    The solution rheology of different generations of hyperbranched polyesters in N-methyl-2- pyrrolidinone (NMP) solvent was examined in this study. The solutions exhibited Newtonian behavior over a wide range of polyester concentrations. Also, the relative viscosities of poly(amido...

  6. Superior performance of multilayered fluoropolymer films in low voltage electrowetting

    OpenAIRE

    Papageorgiou, Dimitrios P.; Tserepi, Angeliki; Boudouvis, Andreas G.; Papathanasiou, Athanasios G.

    2011-01-01

    The requirement for low operational voltage in electrowetting devices, met using thin dielectrics, is usually connected with serious material failure issues. Dielectric breakdown (visible as electrolysis) is frequently evident slightly beyond the onset of the contact angle saturation. Here, plasma enhanced chemical vapor deposition (PECVD) is used to deposit thin fluorocarbon films prior to the spin-coating of Teflon\\textregistered amorphous fluoropolymer on tetraethoxysilane (TEOS) substrate...

  7. Thermo-/pH-dual responsive properties of hyperbranched polyethylenimine grafted by phenylalanine.

    Science.gov (United States)

    Chen, Jie; Xia, Jialiang; Tian, Huayu; Tang, Zhaohui; He, Chaoliang; Chen, Xuesi

    2014-01-01

    Novel thermo- and pH-dual responsive amphiphilic copolymers were synthesized based on hyperbranched polyethylenimine (PEI) by grafting L-phenylalanine. The phenylalanine-modified PEI exhibited lower cytotoxicity than commercial PEI. These copolymers showed the phenomena of phase transitions in response to pH and temperature. The dilute copolymer solution at lower pH displayed the higher LCST. Furthermore, LCST increased with the increasing of phenylalanine grafting density. LCST of these copolymers were tunable from 7.2 to 59.6 °C by the degree of amidation and pH of solution. DLS and TEM experiments certified that the copolymer chains aggregated to form small size particles as increasing the temperature above LCST. For these reasons, the obtained smart copolymers were considered to be potential gene/drug carriers in biomedical field.

  8. A liquid xenon ionization chamber in an all-fluoropolymer vessel

    CERN Document Server

    LePort, F; Baussan, E; Breidenbach, M; Conley, R; DeVoe, R; Diez, M M; Fairbank, W; Farine, J; Fierlinger, P; Flatt, B; Gratta, G; Green, M; Hall, C; Hall, K; Hallman, D; Hargrove, C K; Hodgson, J; Jeng, S; Koffas, T; Leonard, D S; Mackay, D; Martin, Y; Neilson, R; O'Sullivan, K; Odian, A; Ounalli, L; Piepke, A; Pocar, A; Prescott, C Y; Rowson, P C; Schenker, D; Sinclair, D; Skarpaas, K V; Stekhanov, V; Strickland, V; Virtue, C; Vuilleumier, J L; Vuilleumier, J M; Waldman, S J; Wamba, K; Weber, P; Wodin, J; Woisard, D

    2006-01-01

    A novel technique has been developed to build vessels for liquid xenon ionization detectors entirely out of ultra-clean fluoropolymer. We describe the advantages in terms of low radioactivity contamination, provide some details of the construction techniques, and show the energy resolution achieved with a prototype all-fluoropolymer ionization detector.

  9. Thermal stability of aliphatic hyperbranched polyesters

    Directory of Open Access Journals (Sweden)

    Vuković Jasna

    2002-01-01

    Full Text Available The influence of the molar mass (generation, number and type of end groups on the thermal stability of aliphatic hyperbranched polyesters are presented in this study. Different end groups were obtained by modification of the samples with chlorides of propionic acid and stearic acid. The thermal stability of the hyperbranched polyesters was determined by thermogravimetry using a NET-ZSCH TG 209 instrument in nitrogen atmosphere at a heating rate of 10°C/min. A comparison of the temperatures obtained for mass losses of 5 20 and 40 wt% for unmodified samples showed that the thermal stability increased up to the fourth generation and then remained practically constant. An increase in the thermal stability of modified samples of the second, third and fourth generation was observed.

  10. Novel Hyperbranched Polyurethane Brushes for Biomedical Applications

    Institute of Scientific and Technical Information of China (English)

    Ton; Loontjens; Bart; Plum

    2007-01-01

    1 Results The objective was to make hyperbranched (HB) polyurethane brushes with reactive end groups, to coat biomedical devices and to enable the introduction of various functionalities that are needed to fulfill biomedical tasks.Biomedical materials should fulfill at least three requirements: (1) good mechanical properties, (2) good biocompatibility and (3) provided with functionalities to perform the required tasks. Since polyurethanes are able to fulfill the first 2 requirements we focused in this w...

  11. Fluoropolymer - TiO2 coatings and their superhydrophilicity

    DEFF Research Database (Denmark)

    Søgaard, Erik Gydesen; Simonsen, Morten Enggrob; Jepsen, Henrik;

    of a statistical planning procedure. The dip coating of object glass with 24 different mixtures created the basis for the investigation. A water droplet was put on the surface of each coating and in total 1900 images of its contact angle were taken as function of time. Hardness of the coatings were measured......In this work the superhydrophilicity of coatings on fluoropolymer were investigated. The different coatings were prepared by help of P25 Degussa TiO2 powder, titaniumisopropoxide, Lumiflon® and two different curing agents (BL 3175 and Cymel 303). The investigations were performed by help...

  12. Towards Enhanced Gas Sensor Performance with Fluoropolymer Membranes

    Directory of Open Access Journals (Sweden)

    Thorsten Graunke

    2016-09-01

    Full Text Available In this paper we report on how to increase the selectivity of gas sensors by using fluoropolymer membranes. The mass transport of polar and non-polar gases through a polymer membrane matrix was studied by systematic selection of polymers with different degrees of fluorination, as well as polymers whose monomers have ether groups (-O- in addition to fluorine groups (-F. For the study, a set of application-relevant gases including H2, CO, CO2, NO2, methane, ethanol, acetone, and acetaldehyde as well as various concentrations of relative humidity were used. These gases have different functional groups and polarities, yet have a similar kinetic diameter and are therefore typically difficult to separate. The concentrations of the gases were chosen according to international indicative limit values (TWA, STEL. To measure the concentration in the feed and permeate, we used tin-dioxide-based metal oxide gas sensors with palladium catalyst (SnO2:Pd, catalytic sensors (also SnO2:Pd-based and thermal conductivity sensors. This allows a close examination of the interdependence of diffusion and physicochemical operating principle of the sensor. Our goal is to increase the selectivity of gas sensors by using inexpensive fluoropolymer membranes. The measurements showed that through membranes with low polarity, preferably non-polar gases are transported. Furthermore, the degree of crystallization influences the permeability and selectivity of a polymer membrane. Basically the polar polymers showed a higher permeability to water vapor and polar substances than non-polar polymer membranes.

  13. Synthesis and Characterization of Aliphatic-Aromatic Hyperbranched Polyesters

    Institute of Scientific and Technical Information of China (English)

    唐黎明; 张晓龙; 邱藤; 刘德山

    2002-01-01

    Hyperbranched polymers possess special architectures and have potential applications in various areas. In this study, two AB2 monomers, dipropyl 5-(hydroxyethoxy) isophthalate (I) and 5-hydroxyethoxyisophthaic acid (II), were prepared. By bulk polycondensation of each monomer, two aliphatic-aromatic hyperbranched polyesters were prepared and characterized by 1H-nuclear magnetic resonance (1H-NMR), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and scanning electron microscopy (SEM). Compared with all-aromatic hyperbranched polyesters, the prepared polymers showed lower glass transition temperatures in connection with the moderate decrease in their decomposition temperatures.

  14. Vapor deposition of cross-linked fluoropolymer barrier coatings onto pre-assembled microfluidic devices.

    Science.gov (United States)

    Riche, Carson T; Marin, Brandon C; Malmstadt, Noah; Gupta, Malancha

    2011-09-21

    The interior surfaces of pre-assembled poly(dimethylsiloxane) (PDMS) microfluidic devices were modified with a cross-linked fluoropolymer barrier coating that significantly increased the chemical compatibility of the devices. PMID:21850298

  15. Study of high-speed interaction processes between fluoropolymer projectiles and aluminum-based targets

    Institute of Scientific and Technical Information of China (English)

    Evgeny A. KHMELNIKOV; Alexey V. STYROV; Konstantin V. SMAGIN; Natalia S. KRAVCHENKO; Valery L. RUDENKO; Vladimir I. FALALEEV; Sergey S. SOKOLOV; Artem V. SVIDINSKY; Natalia F. SVIDINSKAYA

    2015-01-01

    The experimental results and numerical modeling of penetration process of fluoropolymer projectiles in aluminum-based targets are pre-sented. Analysis of mathematical models for interaction of elastoplastic projectile and target without taking additional energy released during interaction of fluoropolymer and aluminum into consideration is carried out. Energy fraction which is spent effectively on the increase in cavity volume is determined. The experimental and calculated results of penetration by combined and inert projectiles are compared.

  16. Preparation of lotus-like superhydrophobic fluoropolymer films

    International Nuclear Information System (INIS)

    Styrene and 2,2,3,4,4,4-hexafluorobutyl methacrylate copolymers were synthesized by bulk polymerization, and the superhydrophobic copolymer films were prepared subsequently using phase separation technique. The copolymer was dissolved in tetrahydrofuran, and then added ethanol into the solution thereafter, to induce phase separation. The microstructures of the polymer films were controlled by the degree of phase separation, which was enhanced properly by the concentration of ethanol. The surface morphology of the films, observed by environmental scanning electron microscope, is similar to that of the lotus leaf. The contact angle and sliding angle were measured as 154.3 deg. and 5.8 deg., respectively. The excellent superhydrophobic property demonstrated that the phase separation technique is useful for preparing lotus-like fluoropolymer films.

  17. Hyperbranched Polyurethane Acrylate Applied to UV Curable Flame Retardant Coatings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ UV curable hyperbranched prepolymers based on amine-ester, ester-amide and ether-amide started with AB2-type monomers have been prepared by the authors[1~3]. A se-ries of work on allyl ether maleate hyperbranched polyesters for UV curing coatings by Hult and his colleagues has been reported[4]. However, the UV cured films from those materials are all flammable when attached to fire without addition of flame retardants.

  18. Miktoarms hyperbranched polymer brushes:One-step fast synthesis by parallel click chemistry and hierarchical self-assembly

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Spherical molecular brushes with amphiphilic heteroarms were facilely synthesized by grafting the arms of hydrophobic 2-azidoethyle palmitate and hydrophilic monoazide-terminated poly(ethylene glycol) onto the core of alkyne-modified hyperbranched polyglycerol (HPG) with high molecular weight (Mn=122 kDa) via one-pot parallel click chemistry.The parallel click grafting strategy was demonstrated to be highly efficient (~100%),very fast (~ 2 h) and well controllable to the amphilicity of molecular brushes.Through adjusting the feeding ratio of hydrophobic and hydrophilic arms,a series of brushes with different arm ratios were readily obtained.The resulting miktoarms hyperbranched polymer brushes (HPG-g-C16/PEG350) were characterized by hydrogen-nuclear magnetic resonance (1H NMR),Fourier transform infrared (FT-IR) spectroscopy,gel permeation chromatography (GPC),and differential scanning calorimetry (DSC) measurements.The spherical molecular brushes showed high molecular weights up to 230 kDa,and thus could be visualized by atomic force microscopy (AFM).AFM and dynamic laser light scattering (DLS) were employed to investigate the self-assembly properties of amphiphilic molecular brushes with closed proportion of hydrophobic and hydrophilic arms.The brushes could self-assemble hierarchically into spherical micelles,and network-like fibre structures,and again spherical micelles by addition of n-hexane into the dichloromethane or chloroform solution of brushes.In addition,this kind of miktoarms polymer brush also showed the ability of dye loading via host-guest encapsulation,which promises the potential application of spherical molecular brushes in supramolecular chemistry.

  19. SOLUTION RHEOLOGY OF HYPERBRANCHED POLYESTERS AND THEIR BLENDS WITH LINEAR POLYMERS

    Science.gov (United States)

    In this study, the rheological properties of different generations of hyperbranched polyesters in 1-methyl-2-pyrrolidinone solvent and their blends with poly(2-hydroxyethyl methacrylate) have ben investigated. All the hyperbranched polyester solutions exhibited Newtonian behavior...

  20. Local orientational mobility in regular hyperbranched polymers

    CERN Document Server

    Dolgushev, Maxim; Fürstenberg, Florian; Guérin, Thomas

    2016-01-01

    We study the dynamics of local bond orientation in regular hyperbranched polymers modeled by Vicsek fractals. The local dynamics is investigated through the temporal autocorrelation functions of single bonds and the corresponding relaxation forms of the complex dielectric susceptibility. We show that the dynamic behavior of single segments depends on their remoteness from the periphery rather than on the size of the whole macromolecule. Remarkably, the dynamics of the core segments (which are most remote from the periphery) shows a scaling behavior that differs from the dynamics obtained after structural average. We analyze the most relevant processes of single segment motion and provide an analytic approximation for the corresponding relaxation times. Furthermore, we describe an iterative method to calculate the orientational dynamics in the case of very large macromolecular sizes.

  1. Crosslinked polyurethanes based on hyperbranched polymers

    Directory of Open Access Journals (Sweden)

    Vuković Jasna

    2008-01-01

    Full Text Available In this paper, two samples of polyurethane (PU crosslinked with hydroxy -functonal hyperbranched aliphatic polyester of the second pseudo generation were investigated. For the synthesis of these crosslinked PUs two different macrodiols were used: poly(tetramethyleneoxide (PTMO for PUPTMO and ethylene oxide-poly(dimethylsiloxane-ethylene oxide (PDMS-EO for PUPDMS-EO sample. Synthesized samples behave as elastomers and have yellow color. Obtained results show that swelling degree of the sample PUPDMS-EO in N-methyl-2-pyrrolidinon (NMP determined at room temperature is higher than for the sample PUPTMO. It has been also observed that thermal properties of these polyurethane networks can be changed by incorporation of siloxane sequences in their structure.

  2. POROUS AMORPHOUS FLUOROPOLYMER FILMS WITH ULTRALOW DIELECTRIC CONSTANT

    Institute of Scientific and Technical Information of China (English)

    DING SHI-JIN; WANG PENG-FEI; ZHANG WEI; WANG JI-TAO; WEI WILLIAM LEE; ZHANG YE-WEN; KIA ZHONG-FU

    2000-01-01

    With the development of ultralarge scale integrated circuit, new interlayer dielectrics with low dielectric constant for multilevel interconnections are required, instead of conventional SiO2 films. For the sake of seeking perfect dielectrics, amorphous fluoropolymer (AF) thin film with a thickness of about 0.9μm has been prepared by spin-coating method, following the principle of phase separation. By capacitance-voltage (C-V) measurements the dielectric constant of the thin film is equal to 1.57 at 1 MHz, which is attributed to numerous pores contained in the film matrix. X-ray photoelectron spectroscopy (XPS) spectra show that after annealing, about 71% CFa groups in the AF film have decomposed into CF2, CF, etc. This leads to the increase of CF2 groups by three times and CF groups by 8% in the AF film. In a word, compared with the film without being annealed, about 25% carbon, 7% fluorine and 12% oxygen atoms will be lost after annealing at 400℃ for 30min.

  3. Surface and thermomechanical characterization of polyurethane networks based on poly(dimethylsiloxane and hyperbranched polyester

    Directory of Open Access Journals (Sweden)

    M. V. Pergal

    2013-10-01

    Full Text Available Two series of polyurethane (PU networks based on Boltorn® hyperbranched polyester (HBP and hydroxyethoxy propyl terminated poly(dimethylsiloxane (EO-PDMS or hydroxy propyl terminated poly(dimethylsiloxane (HPPDMS, were synthesized. The effect of the type of soft PDMS segment on the properties of PUs was investigated by Fourier transform infrared spectroscopy (FTIR, contact angle measurements, surface free energy determination, X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM, atomic force microscopy (AFM, dynamic mechanical thermal analysis (DMTA and differential scanning calorimetry (DSC. The surface characterization of PUs showed existence of slightly amphiphilic character and it revealed that PUs based on HP-PDMS have lower surface free energy, more hydrophobic surface and better waterproof performances than PUs based on EO-PDMS. PUs based on HPPDMS had higher crosslinking density than PUs based on EO-PDMS. DSC and DMTA results revealed that these newlysynthesized PUs exhibit the glass transition temperatures of the soft and hard segments. DMTA, SEM and AFM results confirmed existence of microphase separated morphology. The results obtained in this work indicate that PU networks based on HBP and PDMS have improved surface and thermomechanical properties.

  4. 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.

  5. SYNTHESIS OF AN EPOXY-TERMINATED HYPERBRANCHED AROMATIC POLYESTER

    Institute of Scientific and Technical Information of China (English)

    Xia Wang; W.J. Feast

    2002-01-01

    An epoxy-terminated hyperbranched aromatic polyester (P3) was synthesized from a hyperbranched aromaticpolyester containing carboxylic acid end groups (P1), which was derived from the condensation polymerization of the AB2monomer, 5-acetoxyisophthalic acid. Polymer P1 was converted into the polymeric acid chloride by reaction with thionylchloride. The acid chloride was reacted with ethanol and glycidol to form a poly(ethyl ester) (P2) and an epoxy terminatedmaterial (P3), respectively. The reaction conditions in each step of these processes had to be controlled very carefully toavoid unwanted cross-linking reactions. The characterization of products and intermediates, including molecular weightdistributions and thermal properties, are reported.

  6. Dynamics of Hyperbranched Polymers under Confinement

    Science.gov (United States)

    Androulaki, Krystallenia; Chrissopoulou, Kiriaki; Anastasiadis, Spiros H.; Prevosto, Daniele; Labardi, Massimiliano

    2015-03-01

    The effect of severe confinement on the dynamics of three different generations of hyperbranched polyesters (Boltorns) is investigated by Dielectric Spectroscopy. The polymers are intercalated within the galleries of natural Na+-MMT, thus, forming 1nm polymer films confined between solid walls. The Tg's of the polymers determined by DSC show a clear dependence on the generation whereas the transition is completely suppressed when all the polymer chains are intercalated. The dynamic investigation of the bulk polymers reveals two sub-Tg processes, with similar behavior for the three polymers with the segmental relaxation observed above the Tg of each. For the nanocomposites, where all polymers are severely confined, the dynamics show significant differences compared to that of the bulk polymers. The sub-Tg processes are similar for the three generations but significantly faster and with weaker temperature dependence than those in the bulk. The segmental process appears at temperatures below the bulk polymer Tg, it exhibits an Arrhenius temperature dependence and shows differences for the three generations. A slow process that appears at higher temperatures is due to interfacial polarization. Co-financed by the EU and Greek funds through the Operational Program ``Education and Lifelong Learning'' of the NSRF-Research Funding Program: THALES-Investing in knowledge society through the Eur. Social Fund (MIS 377278) and COST Action MP0902-COINAPO.

  7. Thermal evaporated hyperbranched Ag nanostructure as an effective secondary-electron trapping surface coating

    OpenAIRE

    Y. N. He; W. B. Peng; W. Z. Cui; Ye, M.; Zhao, X L; Wang, D.; Hu, T. C.; Wang, R.; Li, Y.

    2016-01-01

    We study secondary electron yield (SEY) suppression of silver using a hyperbranched nanostructure obtained by thermal evaporation. First, we perform thermal evaporation at different residual gas pressures for studying the influence of pressure on surface morphologies. A self-assembled hyperbranched Ag nanostructure has been achieved at 100 Pa. Then, we further investigate the detailed formation process of the self-assembled hyperbranched Ag nanostructure qualitatively and find it to be domina...

  8. 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.

  9. Ultra-thin fluoropolymer buffer layer as an anode stabilizer of organic light emitting devices

    International Nuclear Information System (INIS)

    We have investigated the effect of thin fluoro-acrylic polymer as an anode stabilizer on the lifetime of an organic light emitting device (OLED). Surface chemical properties of commercial fluoropolymer, FC-722 (Fluorad(TM) of 3M), on indium-tin oxide (ITO) were characterized by x-ray photoemission spectroscopy. An OLED with 1 nm thick fluoropolymeric film showed identical brightness and efficiency behaviour and improved operational stability compared with the reference device with UV-O3 treated ITO. The improvement in the lifetime was accompanied by the suppression of the voltage increase at the initial stage of constant-current driving, which can be attributed to the action of the FC-722 layer by smoothing the ITO surface. Fluoropolymer coating, therefore, improves the lifetime of the small molecular OLED by the simple and reliable anode-stabilizing process

  10. Ultra-thin fluoropolymer buffer layer as an anode stabilizer of organic light emitting devices

    Science.gov (United States)

    Yang, Nam Chul; Lee, Jaeho; Song, Myung-Won; Ahn, Nari; Kim, Mu-Hyun; Lee, Songtaek; Doo Chin, Byung

    2007-08-01

    We have investigated the effect of thin fluoro-acrylic polymer as an anode stabilizer on the lifetime of an organic light emitting device (OLED). Surface chemical properties of commercial fluoropolymer, FC-722 (Fluorad™ of 3M), on indium-tin oxide (ITO) were characterized by x-ray photoemission spectroscopy. An OLED with 1 nm thick fluoropolymeric film showed identical brightness and efficiency behaviour and improved operational stability compared with the reference device with UV-O3 treated ITO. The improvement in the lifetime was accompanied by the suppression of the voltage increase at the initial stage of constant-current driving, which can be attributed to the action of the FC-722 layer by smoothing the ITO surface. Fluoropolymer coating, therefore, improves the lifetime of the small molecular OLED by the simple and reliable anode-stabilizing process.

  11. Stimulus responsive fluorescent hyperbranched polymers and their applications

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Fluorescent hyperbranched polymers (FHBPs),which combine the versatile fluorescent property with unique characteristics of hyperbranched architecture,are desirable candidates for stimulus responsive materials.This review demonstrates the structure and environment-dependent emission behaviors of a series of FHBPs.AEE active FHBPs showing opposite performance to ACQ effect are used to sensitively detect explosives and a superamplification effect is found.Specially designed FHBPs can complex with metal ions,leading to fluorescence turn-off due to complex quenching effect.The protonation of amino-containing FHBPs exhibits pH-dependent fluorescence responses to solution acidity.Some FHBPs containing responsive moieties are photo-and thermo-sensitive,and show potential applications as smart materials.

  12. Modification of polylactide bioplastic using hyperbranched polymer based nanostructures

    Science.gov (United States)

    Bhardwaj, Rahul

    Polylactide (PLA) is the most well known renewable resource based biodegradable polymer. The inherent brittleness and poor processability of PLA pose considerable technical challenges and limit its range of commercial applications. The broad objective of this research was to investigate novel pathways for polylactide modification to enhance its mechanical and rheological properties. The focus of this work was to tailor the architecture of a dendritic hyperbranched polymer (HBP) and study its influence on the mechanical and rheological properties of PLA bioplastic. The hyperbranched polymers under consideration are biodegradable aliphatic hydroxyl-functional hyperbranched polyesters having nanoscale dimensions, unique physical properties and high peripheral functionalities. This work relates to identifying a new and industrially relevant research methodology to develop PLA based nanoblends having outstanding stiffness-toughness balance. In this approach, a hydroxyl functional hyperbranched polymer was crosslinked in-situ with a polyanhydride (PA) in the PLA matrix during melt processing, leading to the generation of new nanoscale hyperbranched polymer based domains in the PLA matrix. Transmission electron microscopy and atomic force microscopy revealed the "sea-island" morphology of PLA-crosslinked HBP blends. The domain size of a large portion of the crosslinked HBP particles in PLA matrix was less than 100 nm. The presence of crosslinked hyperbranched polymers exhibited more than 500% and 800% improvement in the tensile toughness and elongation at break values of PLA, respectively, with a minimal sacrifice of tensile strength and modulus as compared to unmodified PLA. The toughening mechanism of PLA in the presence of crosslinked HBP particles was comprised of shear yielding and crazing. The volume fraction of crosslinked HBP particles and matrix ligament thickness (inter-particle distance) were found to be the critical parameters for the toughening of PLA. The

  13. Immobilization of antimicrobial peptide IG-25 onto fluoropolymers via fluorous interactions and click chemistry

    OpenAIRE

    Santos, Catherine M.; Kumar, Amit; Kolar, Satya S.; Contreras-Caceres, Rafael; McDermott, Alison; Cai, Chengzhi

    2013-01-01

    We report a practical method for biofunctionalization of fluoropolymers based on non-covalent, fluorous interactions and click chemistry which allows incorporation of biomolecules under physiological solutions. We demonstrate the method by immobilization of an antimicrobial peptide (AMP) on fluorous thin films and fluorosilicone contact lens. The fluorous surfaces were dip-coated with fluorous-tagged oligo(ethylene) chain terminated with a reactive group, such as an alkynyl group. This simple...

  14. Portable smartphone quantitation of prostate specific antigen (PSA) in a fluoropolymer microfluidic device

    OpenAIRE

    Barbosa, Ana I.; Gehlot, Poonam; Sidapra, Kalpita; Edwards, Alexander D.; Reis, Nuno M.

    2015-01-01

    We present a new, power-free and flexible detection system named MCFphone for portable colorimetric and fluorescence quantitative sandwich immunoassay detection of prostate specific antigen (PSA). The MCFphone is composed by a smartphone integrated with a magnifying lens, a simple light source and a miniaturised immunoassay platform, the Microcapillary Film (MCF). The excellent transparency and flat geometry of fluoropolymer MCF allowed quantitation of PSA in the range 0.9 to 60 ng/ml with < ...

  15. Hyperbranched Polymer-Based Electrolyte for Lithium Polymer Batteries

    Institute of Scientific and Technical Information of China (English)

    Takahito Itoh

    2005-01-01

    @@ 1Introduction Solid polymer electrolytes have attracted much attention as electrolyte materials for all solid-state recharge able lithium batteries, and poly ( ethylene oxide) ( PEO)-based polymer electrolytes are among the most intensively studied systems[1-3]. Hyperbranched polymers have unique properties such as completely amorphous, highly soluble in common organic solvent and processible because of the highly branched nature[4,5].

  16. Effect of Pigmentation in Particulate Formation from Fluoropolymer Thermodegradation in Microgravity

    Science.gov (United States)

    Srivastava, Rajiv; McKinnon, J. Thomas; Todd, Paul

    1998-01-01

    Fires aboard spacecraft have occurred as a result of overheated electrical wires and thermodegradation of their insulation, which is composed of fluoropolymers. The particulate products of polymer thermodegradation are only 20-50 run in diameter and are thought to play a role in "polymer fume fever". Therefore an experimental study of the particulates produced by intense ohmic heating of various fluoropolymer-insulated 20 AWG copper wire (representative of spacecraft materials) was undertaken in normal gravity and in microgravity. The 2.2 s drop facility at NASA LeRC and 1.5 s drop facility at the Colorado School of Mines were used to achieve low gravity conditions. Thermophoretic sampling was used for particulate collection. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to characterize the smoke particulates. It was found that the color of PTFE (Polytetrafluoroethylene) insulation has an overwhelming effect on the size, shape, morphology and, composition of the particulates. Size distributions and shape analyses using computerized image analysis showed that particle size distributions were also dependent on the pigment of the fluoropolymer insulation. The influence of pigment was observed in experiments under both normal and microgravity. Under microgravity conditions, owing to the lack of natural convective transport of particulates, much more particle aggregation was observed, and the nature of the aggregates was dependent on the color of the insulation.

  17. Triazatruxene-containing hyperbranched polymers:Microwave-assisted synthesis and optoelectronic properties

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Hyperbranched polymer structures represent a class of high-functionality building blocks with excellent three-dimensional topology for the construction of highly substituted conjugated polymers.In this contribution,an efficient microwave synthesis protocol toward the synthesis of conjugated hyperbranched polymers is presented.A novel series of soluble hyperbranched polyfluorenes (PTF1-PTF3) incorporating triazatruxene moiety as the branch units with various branching degrees have thus been successfully constructed with good yields and high molecular weight via a facile "A2+B2+C3" approach.The structures of the hyperbranched polymers were confirmed by NMR and GPC.Their thermal,optical,and electrochemical properties of the hyperbranched polymers were also investigated.The results showed that introduction of triazatruxene units into the hyperbranched structure endowed the polymer with good thermal stability and highly amorphous properties.Photophysical investigation of PTFx revealed strong blue emission in both solution and solid states.Hyperbranched polymers with higher degree of branching and proper content of linear fluorene units exhibited better photophysical properties in terms of narrow emission spectra and relatively high quantum efficiency as well as improved thermal spectral stability.The triazatruxene branching unit also played a role in raising the HOMO energy levels relative to those of polyfluorenes that would help to improve the charge injection and transport properties.The incorporation of triazatruxene unit into hyperbranched polymers has thus explored an effective avenue for constructing optoelectronic polymers with improved functional characteristics.

  18. SYNTHESIS AND CHARACTERIZATION OF SURFACE-HYPERBRANCHED MAGNETITE NANOPARTICLE FOR BOVINE SERUM ALBUMIN IMMOBILIZATION

    Institute of Scientific and Technical Information of China (English)

    Bifeng Pan; Feng Gao; Hongchen Gu

    2004-01-01

    A hyperbranched polyamidoamine polymer was synthesized on the surface of magnetite nanoparticles to enhance bovine serum albumin (BSA) immobilization efficiency. The amount of immobilized bovine serum albumin (BSA)on the surface-hyperbranched magnetite nanoparticle was up to 2.5 times as much as that of magnetite nanoparticle modified with only amino silane.

  19. Self-healing hyperbranched poly(aroyltriazole)s

    Science.gov (United States)

    Wei, Qiang; Wang, Jian; Shen, Xiaoyuan; Zhang, Xiao A.; Sun, Jing Zhi; Qin, Anjun; Tang, Ben Zhong

    2013-01-01

    The research on self-healing polymers has been a hot topic. The encapsulated-monomer/catalyst, supramolecular self-assembly, and reversible or dynamic covalent bond formation are the prevailingly adopted strategies. The alternative of irreversible covalent bond formation is, however, to be further developed. In this contribution, self-healing hyperbranched poly(aroyltriazole)s of PI and PII sharing such mechanism were developed. The polymers were synthesized by our developed metal-free click polymerizations of bis(aroylacetylene)s and triazide. They are processible and have excellent film-forming ability. High quality homogeneous films and sticks free from defects could be obtained by casting. The scratched films could be self-repaired upon general heating. The cut films and sticks could be healed by stacking or pressing the halves together at elevated temperature. Thus, these hyperbranched polymers could find broad applications in diverse areas, and our design concept for self-healing materials should be generally applicable to other hyperbranched polymers with reactive groups on their peripheries.

  20. HYPERBRANCHED CONJUGATIVE MACROMOLECULES CONSTRUCTED FROM TRIPLE-BOND BUILDING BLOCKS

    Institute of Scientific and Technical Information of China (English)

    Matthias H(a)uβler; Hong-chen Dong; Jacky Wing Yip Lam; Rong-hua Zheng; An-jun Qin; Ben-zhong Tang

    2005-01-01

    Polycyclotrimerization and polycoupling of acetylenic monomers respectively furnish hyperbranched polyarylenes and polyynes with high molecular weights (up to 1 × 106) in high yields (up to 99.9%). The polymers possess low intrinsic viscosities and high thermal stabilities, losing little of their weights when heated to > 400℃. Upon pyrolysis at > 800℃, the polymers graphitize with high char yields (up to 86%). Hyperbranched polyarylenes efficiently emit deep-blue to blue-green lights with fluorescence quantum yields up to 98% and strongly attenuate intense laser pulses with optical power-limiting performances superior to that of C60, a well-known optical limiter. Poly(alkenephenylenes), poly(aroylarylenes) and polyynes are readily cross-linkable by UV irradiation, serving as excellent photoresist materials for the generation of patterns with nanometer resolution. Thin films of hyperbranched polyynes exhibit very high refractive indexes (n up to 1.86). The internal and terminal acetylene moieties of the polyynes readily form complexes with cobalt carbonyls, which can be transformed into soft ferromagnetic ceramics with high magnetic susceptibilities (Ms up to ca. 118 emu/g) and near-zero magnetic losses.

  1. Improving of Mechanical and Shape-Memory Properties in Hyperbranched Epoxy Shape-Memory Polymers

    Science.gov (United States)

    Santiago, David; Fabregat-Sanjuan, Albert; Ferrando, Francesc; De la Flor, Silvia

    2016-03-01

    A series of shape-memory epoxy polymers were synthesized using an aliphatic amine and two different commercial hyperbranched poly(ethyleneimine)s with different molecular weights as crosslinking agents. Thermal, mechanical, and shape-memory properties in materials modified with different hyperbranched polymers were analyzed and compared in order to establish the effect of the structure and the molecular weight of the hyperbranched polymers used. The presence of hyperbranched polymers led to more heterogeneous networks, and the crosslinking densities of which increase as the hyperbranched polymer content increases. The transition temperatures can be tailored from 56 to 117 °C depending on the molecular weight and content of the hyperbranched polymer. The mechanical properties showed excellent values in all formulations at room temperature and, specially, at T_{g}^{{E^' with stress at break as high as 15 MPa and strain at break as high as 60 %. The shape-memory performances revealed recovery ratios around 95 %, fixity ratios around 97 %, and shape-recovery velocities as high as 22 %/min. The results obtained in this study reveal that hyperbranched polymers with different molecular weights can be used to enhance the thermal and mechanical properties of epoxy-based SMPs while keeping excellent shape-memory properties.

  2. Hyperbranched polymer-cored star polyfluorenes as blue light-emitting materials

    Institute of Scientific and Technical Information of China (English)

    HAN Yang; SUN MingHao; FEI ZhuPing; BO ZhiShan

    2008-01-01

    Hyperbranched polymer-cored star polyfluorenes with high molecular weights and narrow molecular weight distribution were prepared by palladium-catalyzed one-pot Suzuki polycondensation of multi-functional cores and an AB-type monomer. The optical, electrochemical and thermal properties of the hyperbranched polymer-cored star polymers were investigated. These polymers exhibited good ther-mal and color stability in solid state, and there was no significant blue-green emission after the poly-mers had been annealed in air for 2.5 h. Their three-dimensional hyperbranched structures could ef-fectively reduce the aggregation of the peripheral rigid linear conjugated polyfluorene chains.

  3. Hyperbranched polymer stars with Gaussian chain statistics revisited.

    Science.gov (United States)

    Polińska, P; Gillig, C; Wittmer, J P; Baschnagel, J

    2014-02-01

    Conformational properties of regular dendrimers and more general hyperbranched polymer stars with Gaussian statistics for the spacer chains between branching points are revisited numerically. We investigate the scaling for asymptotically long chains especially for fractal dimensions df = 3 (marginally compact) and df = 2.5 (diffusion limited aggregation). Power-law stars obtained by imposing the number of additional arms per generation are compared to truly self-similar stars. We discuss effects of weak excluded-volume interactions and sketch the regime where the Gaussian approximation should hold in dense solutions and melts for sufficiently large spacer chains. PMID:24574057

  4. 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....

  5. POLYCYCLOTRIMERIZATION OF DIYNES, A NEW APPROACH TO HYPERBRANCHED POLYPHENYLENES

    Institute of Scientific and Technical Information of China (English)

    Kai-tian Xu; Ben-zhong Tang

    1999-01-01

    Polycyclotrimerization of diynes was explored as a new route to hyperbranched polymers in this investigation.Polymerization of terminal diynes of 1,8-nonadiyne and 1,9-decadiyne was studied using TaCl5, NbCl5, Mo(CO)4(nbd) and [Mo(CO)3cp]2 as catalysts (where nbd = 2,5-norbornadiene, cp = cyclo-pentadiene). A soluble polymer was obtained when the polymerization of 1,9-decadiyne was initiated by TaCl5 at low temperature (0℃). The polymer, however, became partially soluble after purification, possibly due to the postpolymerization-induced crosslinking. NbCl5-catalyzed polymerization of 1,9-bis(trimethylsilyl)-1,8-nonadiyne gave a completely soluble polymer. Soluble polymers were also obtained from the polymerization of 3,9-dodecadiyne initiated by NbCl5, Mo(CO)4(nbd), [Mo(CO)3cp]2, PdCl2-ClSiMe3 and Pd/C-ClSiMe3. IR, UV, and NMR spectroscopic analysis revealed that different catalysts gave polymers with different structures, ranging from linear polyenes to hyperbranched polyphenylenes. The polymers absorb UV light at around 250 nm and emit fluorescence at 340 nm when they are excited at 248 nm.

  6. Using 2D NMR to determine the degree of branching of complicated hyperbranched polymers

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Degree of branching (DB) is a crucial structure parameter of hyperbranched polymers, which can be determined by 1H NMR, quantitative 13C NMR, degradative method, etc. However, for complicated hy-perbranched polymers, intricate structure and severe overlap of spectral signals hinder the determina-tion of DB using traditional methods. In this work, the architecture of complicated hyperbranched polymers has been elucidated with the help of 2D NMR techniques. Using such a method, overlapped NMR signals can be well separated into a two-dimensional space, and additional structural information is also available. Correspondingly, quantitative analysis for complicated systems can be realized. De-termination of DBs for three types of complicated hyperbranched polymers synthesized from step-polymerization, self-condensation vinyl polymerization and self-condensation ring-opening po-lymerization is shown as examples.

  7. A room temperature cured low dielectric hyperbranched epoxy adhesive with high mechanical strength

    Indian Academy of Sciences (India)

    Bibekananda De; Niranjan Karak

    2014-05-01

    A low dielectric constant hyperbranched epoxy thermoset with excellent adhesive and mechanical strength is the demand for advanced electronics and engineering applications. The present investigation provided a room temperature, curable hyperbranched epoxy, obtained by an A2 + B3 polycondensation reaction. The synthesized hyperbranched epoxy was cured by a combined hardener system consisting of a commercial poly(amido-amine) and a first generation aliphatic poly(amido-amine) dendrimer (PAD) prepared by Michael addition reaction of methyl acrylate and aliphatic amines. The thermoset exhibited high mechanical strength, excellent adhesive strength, low dielectric constant, good thermal stability and excellent weather resistance along with very good moisture resistance. The results showed the influence of the amount of PAD on the performance of the thermoset. Thus, the study revealed that the combined poly(amido-amine) cured hyperbranched epoxy has high potential in advanced electrical packaging and microelectronic devices.

  8. Transparent superhydrophobic/translucent superamphiphobic coatings based on silica-fluoropolymer hybrid nanoparticles.

    Science.gov (United States)

    Lee, Seung Goo; Ham, Dong Seok; Lee, Dong Yun; Bong, Hyojin; Cho, Kilwon

    2013-12-01

    This paper describes a simple approach to prepare a transparent superhydrophobic coating and a translucent superamphiphobic coating via spraying silica-fluoropolymer hybrid nanoparticles (SFNs) without any pre- or post-treatment of substrates; these nanoparticles create both microscale and nanoscale roughness, and fluoropolymer acts as a low surface energy binder. We also demonstrate the effects of varying the concentration of the SFN sol on the water and hexadecane repellency and on the transparency of the coated glass substrates. An increase in the concentration of the sol facilitates the transition between the superhydrophobic/transparent and superamphiphobic/translucent states. This transition results from an increase in the discontinuities in the three-phase (solid-liquid-gas) contact line and in the light scattering properties due to micropapillae tuned by varying the concentration of the sol. This versatile and controllable approach can be applied to a variety of substrates over large areas and may provide a wide range of applications for self-cleaning coatings of optoelectronics, liquid-repellent coatings, and microfluidic systems.

  9. Transparent superhydrophobic/translucent superamphiphobic coatings based on silica-fluoropolymer hybrid nanoparticles.

    Science.gov (United States)

    Lee, Seung Goo; Ham, Dong Seok; Lee, Dong Yun; Bong, Hyojin; Cho, Kilwon

    2013-12-01

    This paper describes a simple approach to prepare a transparent superhydrophobic coating and a translucent superamphiphobic coating via spraying silica-fluoropolymer hybrid nanoparticles (SFNs) without any pre- or post-treatment of substrates; these nanoparticles create both microscale and nanoscale roughness, and fluoropolymer acts as a low surface energy binder. We also demonstrate the effects of varying the concentration of the SFN sol on the water and hexadecane repellency and on the transparency of the coated glass substrates. An increase in the concentration of the sol facilitates the transition between the superhydrophobic/transparent and superamphiphobic/translucent states. This transition results from an increase in the discontinuities in the three-phase (solid-liquid-gas) contact line and in the light scattering properties due to micropapillae tuned by varying the concentration of the sol. This versatile and controllable approach can be applied to a variety of substrates over large areas and may provide a wide range of applications for self-cleaning coatings of optoelectronics, liquid-repellent coatings, and microfluidic systems. PMID:24224524

  10. Convenient Synthesis and Enhanced Second-order Nonlinear Optical Property of a Novel Hyperbranched Polymer

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhi-Chao; LI Zhong-An; LI Qian-Qian; ZENG Qi; LI Zhen; YE Cheng; QIN Jin-Gui

    2007-01-01

    A novel hyperbranched polymer (3) was prepared by copolymerization of tri-aldehyde moieties with azo chromophores having two active methelene groups, from "A2+B3" approach based on simple Kneovenagel reaction.For comparison, its analogue linear polymer (5) was also synthesized. The two polymers are soluble in common organic solvents, and exhibit good thermal stability. Interestingly, the hyperbranched polymer demonstrates dramatically enhanced second-order nonlinear optical property with comparison to its linear analogue.

  11. Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

    OpenAIRE

    Francesco Trotta; Fabrizio Caldera; Roberta Cavalli; Andrea Mele; Carlo Punta; Lucio Melone; Franca Castiglione; Barbara Rossi (Duke); Monica Ferro; Vincenza Crupi; Domenico Majolino; Valentina Venuti; Dominique Scalarone

    2014-01-01

    A new hyper-branched water-soluble polymer was synthesized by reacting β-cyclodextrin with pyromellitic dianhydride beyond the critical conditions that allow the phenomenon of gelation to occur. The molar ratio between the monomers is a crucial parameter that rules the gelation process. Nevertheless, the concentration of monomers in the solvent phase plays a key role as well. Hyper-branched β-cyclodextrin-based polymers were obtained performing the syntheses with excess of solvent and cross-l...

  12. Hyperbranched poly(ester amides) - New solubilization enhancers for poorly water-soluble slimepiride

    OpenAIRE

    Reven, Sebastjan; Grdadolnik, Jože; Žagar, Ema; Kristl, Julijana

    2015-01-01

    We considered poly(esteramide) hyperbranched polymers (trade names: Hybrane S1200 and Hybrane HA1690) as enhancers of glimepiride solubility and therewithassociated dissolution rate. We prepared solid dispersions (SD) of glimepiride with hyperbranched polymers (HB) and compared their solubility with those of crystalline and amorphous glimepiride as well as with the solubility of SD of glimepridie with conventional linear polymers, i.ie. Poly(ethylene glycol) and Gelucire (stearoyl macroglycer...

  13. Hyperbranched poly(esteramides) as solubility enhancers for poorly water-soluble drug glimepiride

    OpenAIRE

    Reven, Sebastjan; Grdadolnik, Jože; Žagar, Ema; Kristl, Julijana

    2015-01-01

    The aim of this work was to study the feasibility of using hyperbranched polymers with highly branched structure and a large number of functional groups as solubilization enhancers for poorly water-soluble drugs. Antidiabetic drug glimepiride was used as a model drug and commercially available hyperbranched poly(esteramide)s as drug carriers. The results of in vitro dissolution studies showed significantly enhanced aqueous-solubility of glimepiride in the form of solid dispersions with hyperb...

  14. Preparation of fluorescent hyperbranched polymer materials by end-capping approach

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two kinds of novel fluorescent hyperbranched polymers were synthesized by the end-capping approach.The fluorescent hyperbranched polyether (FPEOTM) was obtained by end capping the hyperbranched poly(hydroxyl ether) (PEOTM) with guest molecules N,N- dimethylaminobenzaldehyde (DMABA).In addition,in the presence of triethylamine,the hyperbranched polysulfone-amine with terminal double bonds (HPSA) was synthesized by polyaddition of a new AB2 type monomer (SAP,sulfone amine piperazine) at 40℃ for 60 h in chloroform solution.Then the fluorescent hyperbranched polysulfone-amine (FHPSA) was prepared by addition of guest molecules N,N-dimethylaminoanilines (DMAA) with the terminal double bonds of HPSA.The two resulting polymers fluoresce yellow-green color in both solid and solution states.The maximum emission wavelength is (460±10) nm and (470±10) nm,respectively.A novel "complex quenching effect" for hyperbranched polymer was observed.The fluorescence can be quenched by transition metal cations such as Ag+,Cu2+ and Fe3+,while alkali and alkaline earth metal cations almost have no influence on the fluorescence intensity.

  15. Nanoplugging Performance of Hyperbranched Polyamine as Nanoplugging Agent in Oil-Based Drilling Fluid

    Directory of Open Access Journals (Sweden)

    Gang Xie

    2015-01-01

    Full Text Available A hyperbranched polyamine was synthesized by self-condensing vinyl polymerization with divinyl sulfone, N-phenyl-p-phenylenediamine, by A2 + BB2' approach. The hyperbranched polyamine was characterized by FT-IR, TGA, and phase analysis light scanning. Average grain diameter of hyperbranched polyamine was 36.7 nm. Hyperbranched polyamine has good thermal stability. Hyperbranched polyamine (HBPA was employed successfully as nanoplugging agent in oil-based drilling fluid system, which could plug nanopore formation in shale formation. HBPA has a little effect on rheological properties of oil-based drilling fluid and the FLAPI and FLHTHP decreased dramatically with an increase of hyperbranched polyamine. Emulsion-breaking voltage has a slight increase, which is beneficial to maintain stability of oil-based drilling fluid. When the HBPA concentration is greater than 1 wt%, plugging rate of oil-based drilling fluid for artificial core is close to 100% and the permeability recovery value can reach 99.7% after adding 1 wt% HBPA, which prove that HBPA has an excellent plugging performance.

  16. Direct Synthesis of Hyperbranched Poly(acrylic acid-co-3-hydroxypropionate

    Directory of Open Access Journals (Sweden)

    Efkan Çatıker

    2015-01-01

    Full Text Available Hyperbranched poly(acrylic acid-co-3-hydroxypropionate (PAcHP was synthesized by base-catalyzed hydrogen transfer polymerization of acrylic acid through one step. The copolymers obtained through solution and bulk polymerization were insoluble in water and all organic solvents tried. Structural and compositional characterizations of hyperbranched PAcHP were performed by using FTIR, solid 13C-NMR, TGA, and titrimetric analysis. Acrylate fraction of the hyperbranched PAcHP obtained via bulk polymerization was determined as 60–65% by comparing TGA curves of hyperbranched PAcHP and pure poly(3-hydroxy propionate (PHP. However, analytical titration of the same sample revealed that acrylic acid units were about 47.3%. The results obtained from TGA and analytical titration were used to evaluate the chemical structure of the copolymer. Hyperbranched PAcHP exhibited hydrogel properties. Swelling behavior of the copolymer was investigated at a wide pH range and ionic strength. The dynamic swelling profiles of hyperbranched PAcHP exhibited a fast swelling behavior in the first hour and achieved the equilibrium state within 12 h in PBS. Depending on the conditions, the copolymers exhibited swelling ratios up to 2100%. As the copolymer has easily biodegradable propionate and versatile functional acrylic acid units, it can be used as not only biodegradable material in medical applications but also raw material in personal care commodities.

  17. 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

  18. 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.

  19. Patterning and biofunctionalization of antifouling hyperbranched polyglycerol coatings.

    Science.gov (United States)

    Moore, Eli; Delalat, Bahman; Vasani, Roshan; Thissen, Helmut; Voelcker, Nicolas H

    2014-07-14

    We demonstrate the patterned biofunctionalization of antifouling hyperbranched polyglycerol (HPG) coatings on silicon and glass substrates. The ultralow fouling HPG coatings afforded straightforward chemical handles for rapid bioconjugation of amine containing biomolecular species. This was achieved by sodium periodate oxidation of terminal HPG diols to yield reactive aldehyde groups. Patterned microprinting of sodium periodate and cell adhesion mediating cyclic peptides containing the RGD sequence resulted in an array of covalently immobilized bioactive signals. When incubated with mouse fibroblasts, the HPG background resisted cell attachment whereas high density cell attachment was observed on the peptide spots, resulting in high-contrast cell microarrays. We also demonstrated single-step, in situ functionalization of the HPG coatings by printing periodate and peptide concurrently. Our results demonstrate the effectiveness of antifouling and functionalized HPG graft polymer coatings and establish their use in microarray applications for the first time. PMID:24956414

  20. The improvement of corrosion resistance of fluoropolymer coatings by SiO2/poly(styrene-co-butyl acrylate) nanocomposite particles

    Science.gov (United States)

    Chen, L.; Song, R. G.; Li, X. W.; Guo, Y. Q.; Wang, C.; Jiang, Y.

    2015-10-01

    The effects of nano-silica particles on the anticorrosion properties of fluoropolymer coatings on mild steel have been investigated in this paper. In order to enhance the dispersibility of nano-silica in fluoropolymer coatings, we treated the surface of nano-silica with poly(styrene-co-butyl acrylate) (P(St-BA)). The surface grafting of P(St-BA) on the nanoparticles were detected using Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric analyzer (TGA), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The surface of nanocomposite coatings and the coating-substrates bond texture were detected by FE-SEM. We also used energy-dispersive X-ray spectroscopy (EDS) to analyze whether the nanocomposite particles were added into the fluoropolymer coatings. In addition, the influences of various nanoparticles on the corrosion resistance of fluoropolymer-coated steel were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results shown that nanocomposite particles can be dispersed better in fluoropolymer coatings, and the electrochemical results clearly shown the improvement of the protective properties of the nanocomposite coatings when 4 wt.% SiO2/P(St-BA) was added to the fluoropolymer coatings.

  1. Adhesion of silver/polypyrrole nanocomposite coating to a fluoropolymer substrate

    Science.gov (United States)

    Horváth, Barbara; Kawakita, Jin; Chikyow, Toyohiro

    2016-10-01

    This paper describes the adhesive interface between a conducting polymer/metal composite and a polytetrafluoroethylene (PTFE) substrate. Strong adhesion was observed from using a Ag/polypyrrole (Ag/PPy) composite on a fluoropolymer substrate, which in most cases has a very low adhesion to different materials. To clarify the adhesion mechanism between the Ag/PPy composite and the PTFE substrate, the interfacial structure was studied by the use of transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Our results show that Ag/PPy composite is absorbed inside the nano-sized pores of PTFE and the composite mechanically interlocks after solidifying, which causes the nanocomposite to stick strongly to the substrate. The use of Ag/PPy coating could be a novel technique for developing electrodes, antennae or other high performance applications as this metal/conductive polymer composite has excellent adhesion properties on various plastics.

  2. The Positive Effects of Hydrophobic Fluoropolymers on the Electrical Properties of MoS2 Transistors

    Directory of Open Access Journals (Sweden)

    Somayyeh Rahimi

    2016-08-01

    Full Text Available We report the improvement of the electrical performance of field effect transistors (FETs fabricated on monolayer chemical vapor deposited (CVD MoS2, by applying an interacting fluoropolymer capping layer (Teflon-AF. The electrical characterizations of more than 60 FETs, after applying Teflon-AF cap, show significant improvement of the device properties and reduced device to device variation. The improvement includes: 50% reduction of the average gate hysteresis, 30% reduction of the subthreshold swing and about an order of magnitude increase of the current on-off ratio. These favorable changes in device performance are attributed to the reduced exposure of MoS2 channels to the adsorbates in the ambient which can be explained by the polar nature of Teflon-AF cap. A positive shift in the threshold voltage of all the measured FETs is observed, which translates to the more desirable enhancement mode transistor characteristics.

  3. Atmospheric vapor phase deposition of nanometer-thick anti-stiction fluoropolymer coatings for silicon surfaces

    Science.gov (United States)

    Itoh, Shintaro; Takahashi, Kazuhiro; Morita, Hiroyuki; Fukuzawa, Kenji; Zhang, Hedong

    2016-06-01

    Anti-stiction coatings for silicon surfaces are a key technology to prevent the failure of nanoelectromechanical systems (NEMS) during operation and improve the forming accuracy in nanoimprint technology. In this study, we propose an atmospheric vapor phase deposition method to coat a silicon surface with fluoropolymers such as the perfluoropolyethers Fomblin Zdol 2000 and Zdol 4000. Thickness distributions, surface energies, coverages, and stiction forces for the deposited films were evaluated experimentally. The proposed method resulted in over 90% coverage with a film thickness of about 1 nm. The film thickness uniformity was around 0.1 nm over an area of 5 × 5 mm2. This coating effectively reduced the stiction forces by half compared with a bare silicon surface.

  4. Self-Healing Superhydrophobic Fluoropolymer Brushes as Highly Protein-Repellent Coatings.

    Science.gov (United States)

    Wang, Zhanhua; Zuilhof, Han

    2016-06-28

    Superhydrophobic surfaces with micro/nanostructures are widely used to prevent nonspecific adsorption of commercial polymeric and/or biological materials. Herein, a self-healing superhydrophobic and highly protein-repellent fluoropolymer brush was grafted onto nanostructured silicon by surface-initiated atom transfer radical polymerization (ATRP). Both the superhydrophobicity and antifouling properties (as indicated for isolated protein solutions and for 10% blood plasma) are well repaired upon serious chemical degradation (by e.g. air plasma). This brush still maintains excellent superhydrophobicity and good antifouling properties even after 5 damage-repair cycles, which opens a new door to fabricate long-term antifouling coatings on various substrates that can be used in harsh environments. PMID:27305351

  5. Morphological change of self-organized protrusions of fluoropolymer surface by ion beam irradiation

    Science.gov (United States)

    Kitamura (Ogawa), Akane; Kobayashi, Tomohiro; Satoh, Takahiro; Koka, Masashi; Kamiya, Tomihiro; Suzuki, Akihiro; Terai, Takayuki

    2013-07-01

    Polytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP) are typical fluoropolymers displaying several desirable technological properties such as electrical insulation and high chemical resistance. When their surfaces are irradiated with ion beams, dense micro-protrusions formed after the emergence and spread of micropores across the entire irradiated area, allowing culture cells to spread on the top of the protrusions. In this study, we investigate the morphological changes introduced in the fluoropolymer surfaces by ion beams as the energy of the beams is increased. When an FEP sample was irradiated with a nitrogen ion beam with an energy of less than 350 keV at 1.0 μA/cm2, protrusions were formed with a density between 2 × 107/cm2 and 2 × 108/cm2. However, at energies higher than 350 keV, the protrusions became sparse, and the density dropped to 5 × 102/cm2. Protrusions appeared sporadically during irradiation at high energies, and the top of the protrusions appeared as spots inside the sample, which were difficult to etch and became elongated as the erosion of the surface progressed. Erosion was caused by sputtering of FEP molecules and evaporation at notably elevated temperatures on the surface. Analysis based on attenuated total reflectance/Fourier transform infrared spectroscopy showed the presence of Cdbnd C bonds as well as -COOH, -Cdbnd O, and -OH bonds on all irradiated samples. Their concentration on the surface densely covered with micro-protrusions was higher than that on the surface with sparse protrusions after irradiation at energies exceeding 350 keV. Thus, we determined a suitable range for the ion energy for creating FEP surfaces densely covered with protrusions.

  6. Synthesis and nonlinear optical properties of a peripherally functionalized hyperbranched polymer by DR1 chromophores.

    Science.gov (United States)

    Scarpaci, Annabelle; Blart, Errol; Montembault, Véronique; Fontaine, Laurent; Rodriguez, Vincent; Odobel, Fabrice

    2009-08-01

    The first peripheral postfunctionalization of a hyperbranched polyimide by nonlinear optic chromophores (DR1 derivative) was achieved using two different routes. The first one consists in the esterification of the terminal carboxylic acid groups, whereas the second is based on copper-catalyzed Huisgen reaction of the terminal propargylic ester groups. The resulting polymers display good solubility in classical organic solvents and good filmability because thick films can be prepared (up to 2.7 mum). The second-order nonlinear optical properties were measured by SHG at 1064 nm and we show that these hyperbranched polymers exhibit good poling efficiency and good thermal stability since the electro-optic activity remains stable up to 130 degrees C. These results illustrate the potential of hyperbranched polymers to host second-order nonlinear optical chromophores to replace dendrimers or classical linear polymers generally used in this area. PMID:20355797

  7. Perfluoroalkyl-Functionalized Hyperbranched Polyglycerol as Pore Forming Agents and Supramolecular Hosts in Polymer Microspheres

    Directory of Open Access Journals (Sweden)

    Olaf Wagner

    2015-08-01

    Full Text Available Perfluoroalkyl-functionalized, hyperbranched polyglycerols that produce stable microbubbles are integrated into a microfluidic emulsion to create porous microspheres. In a previously-presented work a dendrimer with a perfluorinated shell was used. By replacing this dendrimer core with a hyperbranched core and evaluating different core sizes and degrees of fluorinated shell functionalization, we optimized the process to a more convenient synthesis and higher porosities. The new hyperbranched polyglycerol porogens produced more pores and can be used to prepare microspheres with porosity up to 12% (v/v. The presented preparation forms pores with a perfluoroalkyl-functionalized surface that enables the resulting microspheres to act as supramolecular host systems. The microspheres can incorporate gases into the pores and actives in the polymer matrix, while the perfluoroalkylated pore surface can be used to immobilize perfluoro-tagged molecules onto the pores by fluorous-fluorous interaction.

  8. Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

    Directory of Open Access Journals (Sweden)

    Francesco Trotta

    2014-11-01

    Full Text Available A new hyper-branched water-soluble polymer was synthesized by reacting β-cyclodextrin with pyromellitic dianhydride beyond the critical conditions that allow the phenomenon of gelation to occur. The molar ratio between the monomers is a crucial parameter that rules the gelation process. Nevertheless, the concentration of monomers in the solvent phase plays a key role as well. Hyper-branched β-cyclodextrin-based polymers were obtained performing the syntheses with excess of solvent and cross-linking agent, and the conditions for critical dilution were determined experimentally. A hyper-branched polymer with very high water solubility was obtained and fully characterized both as for its chemical structure and for its capability to encapsulate substances. Fluorescein was used as probe molecule to test the complexation properties of the new material.

  9. Graphene oxide and hyperbranched polymer-toughened hydrogels with improved absorption properties and durability

    DEFF Research Database (Denmark)

    Yu, Yang; De Andrade, Leandro Carvalho Xavier; Fang, Liming;

    2015-01-01

    Hyperbranched polymers or/and graphene oxide nanosheets were used to synthesize poly(acrylic acid)-based hybrid hydrogels with high water absorption ability, excellent mechanical properties, and environmental remediation abilities through a novel one-step, cost-effective, and environmentally...... friendly method. The combination of hyperbranched polymers and graphene oxide nanosheets had synergistic effects on the final hybrid hydrogel, especially on the mechanical behaviors of the hydrogels, with Young's modulus, tensile strength at break and elongation at break increasing by 69, 308, and 848...

  10. SYNTHESIS AND CHARACTERIZATION OF HYPERBRANCHED POLYURETHANE-BENZYLTETRAZOLE

    Institute of Scientific and Technical Information of China (English)

    Li-gen Qiao; Wen-fang Shi

    2011-01-01

    A series of hyperbranched polyurethane-benzyltetrazoles (H-PBTZs) with different linkage structures were synthesized via the polycondensation of hexamethylenediisocyanate as an A2 type monomer with (4-(1H-tetrazol-5-yl)benzyl)-diethanolamine (TBDEA) as a BB'2 type monomer in the absence of catalyst at different temperatures.The FTIR,and 13C and 1H-NMR spectroscopy were used to characterize the molecular structures of TBDEA and H-PBTZs as well as the counterpart linear polyurethane-benzyltetrazole (L-PBTZ).The molecular composition was determined by the reaction selectivity that the isocyanate group reacted with the hydroxyl group in diethanolamine segment or the active hydrogen atom on tetrazole ring.Raising reaction temperature was propitious to the reaction of isocyanate group with the active hydrogen atom on tetrazole ring.The degrees of branching (DB) for H-PBTZs obtained from the 1H-NMR spectra increased with raising reaction temperature.The wider molecular weight distribution of 1.7-2.9 for H-PBTZs was obtained via GPC analysis.TGA results showed that H-PBTZs had high thermal stability compared with L-PBTZ.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Mesomorphic ionic hyperbranched polymers: effect of structural parameters on liquid-crystalline properties and on the formation of gold nanohybrids

    Science.gov (United States)

    Nguyen, Hong Hanh; Serrano, Clara Valverde; Lavedan, Pierre; Goudounèche, Dominique; Mingotaud, Anne-Françoise; Viguerie, Nancy Lauth-De; Marty, Jean-Daniel

    2014-03-01

    Branched thermotropic liquid crystals were successfully obtained from ionic interactions between hyperbranched polyamidoamine and sodium dodecylsulfate. These complexes present columnar rectangular and lamellar thermotropic mesophases as demonstrated by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The relationships between the structural characteristics of the polymers (size of the hyperbranched core, hyperbranched or dendritic nature of the core, and substitution ratio) and the mesomorphic properties were studied. In situ formation of gold nanoparticles was then performed. The templating effect of the liquid crystal mesophase resulted in the formation of isotropic nanoparticles, the size of which was dictated by the local organization of the mesophase and by the molar mass of the hyperbranched complex.Branched thermotropic liquid crystals were successfully obtained from ionic interactions between hyperbranched polyamidoamine and sodium dodecylsulfate. These complexes present columnar rectangular and lamellar thermotropic mesophases as demonstrated by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The relationships between the structural characteristics of the polymers (size of the hyperbranched core, hyperbranched or dendritic nature of the core, and substitution ratio) and the mesomorphic properties were studied. In situ formation of gold nanoparticles was then performed. The templating effect of the liquid crystal mesophase resulted in the formation of isotropic nanoparticles, the size of which was dictated by the local organization of the mesophase and by the molar mass of the hyperbranched complex. Electronic supplementary information (ESI) available: NMR, DSC, POM and SAXS data for hyperbranched complexes and associated hybrids. See DOI: 10.1039/c3nr05913h

  16. Synthesis of hyperbranched copolymers by combining enzymatic ring-opening polymerization and A TRP from a novel bifunctional initiator

    Institute of Scientific and Technical Information of China (English)

    Al Peng; CHEN Liang; HU Dehua; CHEN Yanhua; LI Dongshuang; ZHANG Bao; SHA Ke; WANG Jingyuan

    2006-01-01

    The hyperbranched aliphatic polyester P(ε-CL) was synthesized by means of Novozyme435-catalyzed ring-opening polymerization (ROP) of BHB (2, 2-bis(hydroxymethyl) butyric acid). The chains ended with hydroxyl of P(ε-CL) were modified by the esterification of α-bromopropionyl bromide to obtain hyperbranched difunctional macroinitiator, which was used in the ATRP of St. CuCI/HMTETA was used as the catalyst system in the reaction of ATRP to acquire the hyperbranched copolymers polystyrene-blockpoly(2,2-bis(hydroxymethyl) butyric acid). The copolymer was confirmed by NMR and GPC.

  17. High lubrication performance of tribologically oriented fluoropolymer molecules analyzed by polarized infrared microspectroscopy

    Science.gov (United States)

    Sugimoto, Iwao; Miyake, Shojiro

    1990-05-01

    The molecular structural changes induced in sputtered fluoropolymer film by tribological effects is pursued using polarized micro-Fourier-transform-infrared (micro-FTIR) spectroscopy. Hydrogenation of the carbon radicals produced by CF or CC bond cleavage is detected in the mildly rubbed region, together with C■C bond formation. Polarization measurements reveal that a rigid C■C-bond-rich framework is oriented along the sliding direction in a hardly rubbed region. This rigid carbon framework involves CF bonds with low polarizability. This structure greatly contributes to stable lubrication with a low friction coefficient, after the fluctuating lubrication characteristics that occur in the early rubbing stage have stabilized. These molecular structures are decomposed into C 3/4 C and C■C■C bonds through further elimination of CF moieties by abrasive hard rubbing by all means. Finally, they extremely decompose into amorphous carbon and metal carbide under severe conditions involving the reactive metals which appear after the film molecules are worn out.

  18. Morphologies and Superhydrophobicity of Hybrid Film Surfaces Based on Silica and Fluoropolymer

    Institute of Scientific and Technical Information of China (English)

    Ailan QU; Xiufang WEN; Pihui PI; Jiang CHENG; Zhuoru YANG

    2008-01-01

    Fluoropolymer and different kinds of silica particles were used for controlling surface chemistry and morphology,respectively. A superhydrophobic surface originated from strawberry-like or quincunx-shaped composite silica particles was obtained. The dual size particles are obtained by utilizing the graft of different modified silica particles with epoxy functional group and amine functional group. This makes the surface of film form a composite interface to have irregular binary structure which plays an essential role in trapping air between the substrate surface and the liquid droplets to be necessary for high contact angle and low contact anglehysteresis. The maximum contact angle for water on the hybrid film is about 174±2° and the contact angle hysteresis is less than 2°. The surface morphologies, roughness and the wettability on the surface of films containing different structural silica particles were compared. It was shown that the hierarchical irregularly structure with a low roughness factor and high air-trapped ratio is indispensable for superhydrophobic surface.Although this structural surfaces based on composite silica particles play a vital role in governing the surface wettability, it is necessary to combine with a low surface energy to make the surface superhydrophobic.

  19. Solvent-resistant photocurable liquid fluoropolymers for microfluidic device fabrication [corrected].

    Science.gov (United States)

    Rolland, Jason P; Van Dam, R Michael; Schorzman, Derek A; Quake, Stephen R; DeSimone, Joseph M

    2004-03-01

    We report the first fabrication of a solvent-compatible microfluidic device based on photocurable "Liquid Teflon" materials. The materials are highly fluorinated functionalized perfluoropolyethers (PFPEs) that have liquidlike viscosities that can be cured into tough, highly durable elastomers that exhibit the remarkable chemical resistance of fluoropolymers such as Teflon. Poly(dimethylsiloxane) (PDMS) elastomers have rapidly become the material of choice for many recent microfluidic device applications. Despite the advantages of PDMS in relation to microfluidics technology, the material suffers from a serious drawback in that it swells in most organic solvents. The swelling of PDMS-based devices in organic solvents greatly disrupts the micrometer-sized features and makes it impossible for fluids to flow inside the channels. Our approach to this problem has been to replace PDMS with photocurable perfluoropolyethers. Device fabrication and valve actuation were accomplished using established procedures for PDMS devices. The additional advantage of photocuring allows fabrication time to be decreased from several hours to a matter of minutes. The PFPE-based device exhibited mechanical properties similar to those of Sylgard 184 before and after curing as well as remarkable resistance to organic solvents. This work has the potential to expand the field of microfluidics to many novel applications.

  20. EFFECT OF COMPOSITION AND PROCESSING CONDITION ON MICROSTRUCTURAL PROPERTIES AND DURABILITY OF FLUOROPOLYMER/ACRYLIC BLENDS

    Institute of Scientific and Technical Information of China (English)

    Li-Piin Sung; Xiaohong Gu; Derek L. Ho; Forrest. A. Landis; Diep Nguyenc

    2009-01-01

    Fluoropolymer blends have been widely used as binders for exterior coatings because of their excellent resistance to ultra-violet (UV) radiation as well as to many corrosive chemical agents.It is known that the fluorinated component usually has a lower glass transition temperature and easily crystallizes in the final structure depending upon the blend composition and sample annealing condition.We investigated the effect of blend composition and annealing process (slow and fast cooling) on the surface morphology and microstructure a poly(vinylidene fluoride)/poly(methyl methacrylate)(PVDF/PMMA) blend before and after UV exposure.Surface and subsurface microstructures were studied by atomic force microscopy (AFM) and laser scanning confocal microscopy (LSCM).Bulk microstructure of PVDF-coatings before and after UV exposure were characterized using small angle neutron and light scattering.Higher PVDF content and a slow cooling process result in larger spherulite crystallite structure and rougher surface morphology.Significant ordering in the spherulite crystallite structure has been observed on the surface and the bulk films after UV exposure.

  1. FTIR-ATR Monitoring and SEC/RI/MALLS characterization of ATRP synthesized hyperbranched polyacrylates

    OpenAIRE

    Gonçalves, Miguel; Costa, Mário Rui; Dias, Rolando

    2009-01-01

    This work reports the synthesis at 1 L scale of hyperbranched polyacrylates based upon acrylate/diacrylate monomers such as n-butyl acrylate (nBA)/1,6-hexanediol diacrylate (HDDA) and using atom transfer radical polymerization (ATRP). A FTIR-ATR immersion probe was used to monitor the polymerization reaction. FCT

  2. Production of CaCO3/hyperbranched polyglycidol hybrid films using spray-coating technique.

    Science.gov (United States)

    Malinova, Kalina; Gunesch, Manfred; Montero Pancera, Sabrina; Wengeler, Robert; Rieger, Bernhard; Volkmer, Dirk

    2012-05-15

    Biomineralizing organisms employ macromolecules and cellular processing strategies in order to produce highly complex composite materials such as nacre. Bionic approaches translating this knowledge into viable technical production schemes for a large-scale production of biomimetic hybrid materials have met with limited success so far. Investigations presented here thus focus on the production of CaCO(3)/polymer hybrid coatings that can be applied to huge surface areas via reactive spray-coating. Technical requirements for simplicity and cost efficiency include a straightforward one-pot synthesis of low molecular weight hyperbranched polyglycidols (polyethers of 2,3-epoxy-1-propanol) as a simple mimic of biological macromolecules. Polymers functionalized with phosphate monoester, sulfate or carboxylate groups provide a means of controlling CaCO(3) particle density and morphology in the final coatings. We employ reactive spray-coating techniques to generate CaCO(3)/hybrid coatings among which vaterite composites can be prepared in the presence of sulfate-containing hyperbranched polyglycidol. These coatings show high stability and remained unchanged for periods longer than 9 months. By employing carboxylate-based hyperbranched polyglycidol, it is possible to deposit vaterite-calcite composites, whereas phosphate-ester-based hyperbranched polyglycidol leads to calcite composites. Nanoindentation was used to study mechanical properties, showing that coatings thus obtained are slightly harder than pure calcite. PMID:22386308

  3. Hyperbranched red light-emitting phosphorescent polymers based on iridium complex as the core

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Ting; Yu, Lei; Yang, Yong; Li, Yanhu; Tao, Yun [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China); Hou, Qiong [School of Chemistry & Environment, South China Normal University, Guangzhou 510006 (China); Ying, Lei, E-mail: msleiying@scut.edu.cn [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China); Yang, Wei; Wu, Hongbin; Cao, Yong [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China)

    2015-11-15

    A series of hyperbranched π-conjugated light-emitting polymers containing an iridium complex as the branched core unit and polyfluorene or poly(fluorene-alt-carbazole) as the branched segments were synthesized via a palladium catalyzed Suzuki polymerization. Apparent Förster energy transfer in the photoluminescent spectra as thin films was observed, while no discernible characteristic absorbance and photoluminescence of the iridium complex can be realized in dilute solutions. Copolymers based on poly(fluorene-alt-carbazole) as the branched segments demonstrated enhanced highest occupied molecular orbital energy levels relative to those based on polyfluorene. The electroluminescent spectra of these copolymers exclusively showed the characteristic emission of the iridium complex, with corresponding CIE coordinates of (0.67±0.01, 0.31). All devices exhibited relatively slow roll-off of efficiency, and the best device performance with the maximum luminous efficiency of 5.33 cd A{sup −1} was attained by using PFCzTiqIr3 as the emissive layer. These results indicated that the hyperbranched conjugated architectures can be a promising molecular design strategy for efficient electrophosphorescent light-emitting polymers. - Highlights: • Hyperbranched red light-emitting polymers are synthesized. • Red light-emitting iridium complex is used as the branched core unit. • Hyperbranched polymers based on PFCz exhibit higher luminescence. • The highest luminous efficiency of 5.33 cd A{sup −1} is attained.

  4. Production of CaCO3/hyperbranched polyglycidol hybrid films using spray-coating technique.

    Science.gov (United States)

    Malinova, Kalina; Gunesch, Manfred; Montero Pancera, Sabrina; Wengeler, Robert; Rieger, Bernhard; Volkmer, Dirk

    2012-05-15

    Biomineralizing organisms employ macromolecules and cellular processing strategies in order to produce highly complex composite materials such as nacre. Bionic approaches translating this knowledge into viable technical production schemes for a large-scale production of biomimetic hybrid materials have met with limited success so far. Investigations presented here thus focus on the production of CaCO(3)/polymer hybrid coatings that can be applied to huge surface areas via reactive spray-coating. Technical requirements for simplicity and cost efficiency include a straightforward one-pot synthesis of low molecular weight hyperbranched polyglycidols (polyethers of 2,3-epoxy-1-propanol) as a simple mimic of biological macromolecules. Polymers functionalized with phosphate monoester, sulfate or carboxylate groups provide a means of controlling CaCO(3) particle density and morphology in the final coatings. We employ reactive spray-coating techniques to generate CaCO(3)/hybrid coatings among which vaterite composites can be prepared in the presence of sulfate-containing hyperbranched polyglycidol. These coatings show high stability and remained unchanged for periods longer than 9 months. By employing carboxylate-based hyperbranched polyglycidol, it is possible to deposit vaterite-calcite composites, whereas phosphate-ester-based hyperbranched polyglycidol leads to calcite composites. Nanoindentation was used to study mechanical properties, showing that coatings thus obtained are slightly harder than pure calcite.

  5. 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.

  6. 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

  7. 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...

  8. 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.

  9. Nuclear entry of hyperbranched polylysine nanoparticles into cochlear cells

    Directory of Open Access Journals (Sweden)

    Weikai Zhang

    2011-03-01

    Full Text Available Weikai Zhang1, Ya Zhang1, Marian Löbler2, Klaus-Peter Schmitz2, Aqeel Ahmad3, Ilmari Pyykkö1, Jing Zou11Department of Otolaryngology, University of Tampere, Medical School, Tampere, Finland; 2University of Rostock, Institute for Biomedical Engineering, Rostock, Germany; 3Department of Biomedical Engineering and Computational Science, Aalto University, Espoo, FinlandBackground: Gene therapy is a potentially effective therapeutic modality for treating sensorineural hearing loss. Nonviral gene delivery vectors are expected to become extremely safe and convenient, and nanoparticles are the most promising types of vectors. However, infrequent nuclear localization in the cochlear cells limits their application for gene therapy. This study aimed to investigate the potential nuclear entry of hyperbranched polylysine nanoparticles (HPNPs for gene delivery to cochlear targets.Methods: Rat primary cochlear cells and cochlear explants generated from newborn rats were treated with different concentrations of HPNPs. For the in vivo study, HPNPs were administered to the rats' round window membranes. Subcellular distribution of HPNPs in different cell populations was observed with confocal microscope 24 hours after administration.Results: Nuclear entry was observed in various cochlear cell types in vitro and in vivo. In the primary cochlear cell culture, concentration-dependent internalization was observed. In the cochlear organotypic culture, abundant HPNPs were found in the modiolus, including the spiral ganglion, organ of Corti, and lateral wall tissues. In the in vivo study, a gradient distribution of HPNPs through different layers of the round window membrane was observed. HPNPs were also distributed in the cells of the middle ear tissue. Additionally, efficient internalization of HPNPs was observed in the organ of Corti and spiral ganglion cells. In primary cochlear cells, HPNPs induced higher transfection efficiency than did Lipofectamine

  10. Novel hot-melting hyperbranched poly(ester-amine) bearing self-complementary quadruple hydrogen bonding units

    Institute of Scientific and Technical Information of China (English)

    Yi Peng Qiu; Li Ming Tang; Yu Wang; Shi You Guan

    2008-01-01

    Hyperbranched poly(amine-ester)s bearing serf-complementary quadruple hydrogen bonding units display excellent mechanical and temperature-dependent melt rheological properties,which make them suitable as novel hot-melting materials.

  11. Novel epoxy-silica hybrid coatings by using ethoxysilyl-modified hyperbranched poly(ethyleneimine) with improved scratch resistance

    OpenAIRE

    Acebo Gorostiza, Cristina; Fernández Francos, Xavier; Messori, Massimo; Ramis Juan, Xavier; Serra Albet, Àngels

    2014-01-01

    A new hyperbranched poly(ethyleneimine) with ethoxysilyl groups at the chain ends has been synthesized and characterized and then used in epoxy formulations to generate new organic/inorganic hybrid materials. Formulations of different proportions of diglycidylether of bisphenol A and the prepared ethoxysilylated hyperbranched poly(ethyleneimine) were maintained in a thermostatized controlled humidity chamber to form the inorganic silica network by a sol-gel process and then the epoxy resin wa...

  12. Amine-catalyzed polycyclotrimerization of arylene bipropiolate:A metal-free and regioselective route to hyperbranched polymer

    Institute of Scientific and Technical Information of China (English)

    JIM; Cathy; K; W; LAM; Jacky; W; Y; HAEUSSLER; Matthias

    2008-01-01

    This paper presents a new synthetic route to hyperbranched polymer. An arylene bipropiolate monomer,dimethylmethylenebis(1,4-phenylene) bipropiolate,was prepared by a one-step esterification reaction of bisphenol A with propiolic acid. Polycyclotrimrtization of the monomer was effected by reflux in dimethylformamide(DMF),producing a soluble hyperbranched poly(aroxycarbonylphenylene) in a good yield. The polymer was perfectly branched with a degree of branching of 100%.

  13. Stability of radicals in electron-irradiated fluoropolymer film for the preparation ofgraft copolymer fuel cell electrolyte membranes

    DEFF Research Database (Denmark)

    Larsen, Mikkel Juul; Ma, Yue; Qian, Huan;

    2010-01-01

    The content of radicals in the base polymer film before and after grafting is an important issue in theproduction and use of membranes for electrochemical devices by radiation grafting. In this work a methodhas been developed for determination of relative radical content in fluoropolymer films...... temperature which decreases polymerchain mobility. At room temperature decay of radicals in the crystallites too is indicated, although at a lowerrate. In order to obtain reasonable grafting yield storage should therefore be as short or cold as possible. Allradicals have been found to disappear...

  14. 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...

  15. 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 ...

  16. 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 ...

  17. DEGREE OF BRANCHING OF THE HYPERBRANCHED POLYMERS RESULTED FROM AB2 POLYCONDENSATION WITH SUBSTITUTION EFFECT

    Institute of Scientific and Technical Information of China (English)

    Zhi-ping Zhou; De-yue Yan

    2011-01-01

    The analytical expressions of the various structural units and the average degree of branching for the hyperbranched polymers resulted from AB2 polycondensation with substitution effect were derived by the kinetic mechanism.The reactivity difference between the B group in linear unit and that in terminal group has great effect on the molecular parameters of the products obtained.The concentration of terminal units has a maximum with the increase of the conversion of A groups (x).The higher the reactivity ratio (r) of linear B group to branched one is,the later the maximum appears and the larger it is.The degree of branching of the hyperbranched polymers obtained is controllable by adjusting the parameters ofr andx,which increases with increasing both x and r.

  18. Hyperbranched polycarbonate-based multimolecular micelle with enhanced stability and loading efficiency.

    Science.gov (United States)

    Su, Wei; Luo, Xiao-Hua; Wang, Hua-Fen; Li, Lei; Feng, Jun; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2011-02-16

    We herein develop a facile catalyst-free method to prepare hyperbranched hydroxyl-enriched aliphatic polycarbonate according to SCROP strategy. PEG-attached multiarm hyperbranched copolymer HEHDO-star-mPEG was further designed. It was found that HEHDO-star-mPEG can self-assemble into supramolecular multimolecular micelles in water. HEHDO-star-mPEG micelle showed excellent stability with respect to micellar size upon dilution, and displayed good cell-biocompatibility. An anticancer drug of doxorubicin with hydrogen-bonding functionality was incorporated into obtained micelles to establish a drug delivery system model. A high drug-loading content as well as sustained release pattern for HEHDO-star-mPEG based delivery system was achieved.

  19. An infrared spectroscopic study of H-bond network in hyperbranched polyester polyol

    Science.gov (United States)

    Žagar, Ema; Grdadolnik, Jože

    2003-10-01

    A FTIR study of aliphatic hyperbranched polyester of the fourth generation Boltorn H40 (BH40) is presented. In order to properly assign the main vibrational bands in infrared spectrum temperature measurements, hydration and H/D exchange experiments were performed. Beside these experiments, difference spectroscopy, 2D generalized correlation infrared spectroscopy (2-DGCS) and band fitting procedure were employed to study the main interactions in polymer. On the basis of the detected interactions between various groups the structure of a H-bond network in hyperbranched polyester is proposed. Three main H-bond interactions were detected. Besides CO⋯HO and HO⋯HO a third type of H-bond is present (CO⋯HO⋯HO). A minor type of interactions represent the hydrogen bond formed with the carboxyl COOH group and impurities, which may be present in lower concentration.

  20. Novel Method of Hyperbranched Polymer Modified Nano-SiO2-Grafting Hyperbranched Poly (amide-ester) from Nano-SiO2 by One-Step Polycondensation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; LI Jie; SUN Rui-min; LUO Yun-jun

    2008-01-01

    A new method of surface chemical modification of nano-SiO2 is proposed in this paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano-SiO2 reacted with AB2-type monomer (N, N-dihydroxyethyl-3-amino methyl propionate) by one-step polycondensation. And the product's Fourer transform infrared (FTIR) graphs and transmission electron microscopy(TEM) images proved that hyperbranched poly (amine-ester) was grafted on nano-SiO2 surface successfully. Results show that the modified nano-SiO2 exhibits excellent dispersion and stability in some solvents such as alcohol and chloroform.

  1. Effect of a hyperbranched polymer over the thermal curing and the photocuring of an epoxy resin

    OpenAIRE

    Morancho Llena, José María; Cadenato Matia, Ana María; Ramis Juan, Xavier; Fernández Francos, Xavier; Flores, Marjorie; Salla Tarragó, José María

    2011-01-01

    In this study, the authors study by calorimetry the influence of hyperbranched polyester Boltron®H40 on the thermal curing and the photocuring of a diglycidyl ether of bisphenol epoxy resin (DGEBA) using ytterbium (III) trifluoromethanesulfonate and triarylsulfonium hexafluorantimonate as thermal and photo cationic initiators, respectively. In the dynamic thermal curing at different heating rates, the authors have seen a decelerating effect when H40 is added to DGEBA, the system with 10% of H...

  2. Low-Stress UV-Curable Hyperbranched Polymer Nanocomposites for High-Precision Devices

    OpenAIRE

    Geiser, Valérie

    2010-01-01

    The aim of this thesis was to investigate the process-structure-property relationships of UV-curable hyperbranched polymer (HBP)/silica nanocomposites. Special attention was paid to the interplay between photo-conversion, rheological behavior, shrinkage, and stress dynamics. This knowledge was used to maximize the shape fidelity and dimensional stability of imprinted nano-patterns made with these nanocomposites. Two different processing routes, ...

  3. Hyperbranched Aromatic Polyesters and Their Application in Blends of Linear Polyamides

    OpenAIRE

    Fan, Zhirong

    2009-01-01

    In the last two decades, hyperbranched (hb) polymers have drawn much attention and obtained intensive research activities both from industry and academia. They are known to have unique and interesting properties which derive from their three dimensional structure and the large number of functional groups. These structural characteristics provide high possibilities for controlling functional group interactions and modifications of other polymers in blends and therefore, they are expected to re...

  4. Spiro-linked hyperbranched architecture in electrophosphorescent conjugated polymers for tailoring triplet energy back transfer.

    Science.gov (United States)

    Shao, Shiyang; Ma, Zhihua; Ding, Junqiao; Wang, Lixiang; Jing, Xiabin; Wang, Fosong

    2012-04-17

    A spiro-linked hyperbranched architecture has been incorporated into electrophosphorescent conjugated polymers for the first time, aiming at simultaneously tailoring the intra- and intermolecular triplet energy back transfer from the phosphorescent guest to the conjugated polymer host. Based on a prototype with this unique structure, slower decay of triplet excitons, and 5-8 fold enhancement of device efficiencies are obtained compared with the conventional blending counterpart.

  5. Molecular dynamics simulation studies of hyperbranched polyglycerols and their encapsulation behaviors of small drug molecules.

    Science.gov (United States)

    Yu, Chunyang; Ma, Li; Li, Ke; Li, Shanlong; Liu, Yannan; Zhou, Yongfeng; Yan, Deyue

    2016-08-10

    Hyperbranched polyglycerol (HPG) is one of the most important hyperbranched polymers (HBPs) due to its interesting properties and applications. Herein, the conformation of HPGs depending on the degree of polymerization (DP) and the degree of branching (DB) is investigated explicitly by molecular dynamics simulations. This study shows that the radius of gyration (Rg) scales as Rg ∼ DP(1/3), which is in close agreement with the result of the SANS experiment. For HPGs with the same DP, the radius of gyration, asphericities and solvent accessible surface area all monotonically decrease with the increase of DB; while for HPGs with the same DB, the molecular anisotropy decreases with the increase of DP. The radial density investigation discloses that the cavities are randomly distributed in the interior of the HPG core to support the "dendritic box effect", which can be used to encapsulate the guest molecules. Interestingly, the terminal groups of HPGs with a high Wiener index (WI) are more favorable to fold back into the interiors than those with the low WI when in water. For the hyperbranched multi-arm copolymer with a HPG core and many polyethylene glycol (PEG) arms, drug encapsulation studies show that the PEG caps can not only effectively prevent tamoxifen from leaving the HPG core, but also encapsulate tamoxifen inside the PEG chains. These simulation results have provided more details for understanding the structure-property relationships of HPGs in water. PMID:27465863

  6. Metal catalyzed synthesis of hyperbranched ethylene and/or .alpha.-olefin polymers

    Science.gov (United States)

    Sen, Ayusman; Kim, Jang Sub; Pawlow, James H.; Murtuza, Shahid; Kacker, Smita; Wojcinski, III, Louis M.

    2001-01-01

    Oily hyperbranched polymers derived from ethylene, propylene, butene and/or a C.sub.5 -C.sub.24 .alpha.-olefin, and a method for their synthesis, are disclosed. The polymers have non-regular microstructures and are characterized by a ratio ({character pullout})of methyl hydrogens centered around 0.85 ppm on the 1H-NMR spectra of the polymers relative to total aliphatic hydrogens of from about 0.40 to about 0.65 for polymers derived from ethylene or butene, and a ratio ({character pullout})of from greater than 0.50 to about 0.65 for polymers derived from propylene. A method for grafting hyperbranched polymers derived from ethylene, propylene, butene and/or a C.sub.5 -C.sub.24 .alpha.-olefin onto aromatic rings in organic molecules and polymers, and the resulting grafted materials, are also disclosed. The hyperbranched polymers and grafted materials are useful, for example, as lubricants and lubricant additives.

  7. 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.)

  8. 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

  9. 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...

  10. 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.

  11. 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

  12. HBP Builder: A Tool to Generate Hyperbranched Polymers and Hyperbranched Multi-Arm Copolymers for Coarse-grained and Fully Atomistic Molecular Simulations

    Science.gov (United States)

    Yu, Chunyang; Ma, Li; Li, Shanlong; Tan, Haina; Zhou, Yongfeng; Yan, Deyue

    2016-05-01

    Computer simulation has been becoming a versatile tool that can investigate detailed information from the microscopic scale to the mesoscopic scale. However, the crucial first step of molecular simulation is model building, particularly for hyperbranched polymers (HBPs) and hyperbranched multi-arm copolymers (HBMCs) with complex and various topological structures. Unlike well-defined polymers, not only the molar weight of HBPs/HBMCs with polydispersity, but the HBPs/HBMCs with the same degree of polymerization (DP) and degree of branching (DB) also have many possible topological structures, thus making difficulties for user to build model in molecular simulation. In order to build a bridge between model building and molecular simulation of HBPs and HBMCs, we developed HBP Builder, a C language open source HBPs/HBMCs building toolkit. HBP Builder implements an automated protocol to build various coarse-grained and fully atomistic structures of HBPs/HBMCs according to user’s specific requirements. Meanwhile, coarse-grained and fully atomistic output structures can be directly employed in popular simulation packages, including HOOMD, Tinker and Gromacs. Moreover, HBP Builder has an easy-to-use graphical user interface and the modular architecture, making it easy to extend and reuse it as a part of other program.

  13. Enhancement-mode operation of multilayer MoS2 transistors with a fluoropolymer gate dielectric layer

    Science.gov (United States)

    Yoo, Geonwook; Choi, Sol Lea; Lee, Suelbe; Yoo, Byungwook; Kim, Sunkook; Oh, Min Suk

    2016-06-01

    Enhancement-mode multilayer molybdenum disulfide (MoS2) field-effect transistors (FETs), which are an immensely important component toward low-power electronics based on a two-dimensional layered semiconductor, are demonstrated using the fluoropolymer CYTOP as a gate dielectric. The fabricated devices exhibit threshold voltage (VTH) of ˜5.7 V with field-effect mobility (μFE) of up to 82.3 cm2/V s, and the characteristics are compared with the depletion-mode characteristics of MoS2 FETs with the cross-linked Poly(4-vinylphenol) gate dielectric (VTH ˜ -7.8 V). UV photoelectron spectroscopy analysis indicates that increased surface potential due to the surface dipole effect of the fluorine group influences the positive VTH shift.

  14. A Versatile Strategy to Synthesize Perfluoropolyether-Based Thermoplastic Fluoropolymers by Alkyne-Azide Step-Growth Polymerization.

    Science.gov (United States)

    Lopez, Gérald; Ameduri, Bruno; Habas, Jean-Pierre

    2016-04-01

    Perfluoropolyether (PFPE)-based thermoplastic fluoropolymers are synthesized by A2 + B2 step-growth polymerization between PFPE-diyne and fluorinated diazides. This versatile method allows synthesizing PFPE-based materials with tunable physicochemical properties depending on the exact nature of the fluorinated segment of the diazide precursor. Semicrystalline or amorphous materials endowed with high thermostability (≈300 °C under air) and low glass transition temperature (≈-100 °C) are obtained, as confirmed by differential scanning calorimetry, thermogravimetry, and rheometry. Step-growth polymerizations can be copper-catalyzed but also thermally activated in some cases, thus avoiding the presence of copper residues in the final materials. This strategy opens up new opportunities to easily access PFPE-based materials on an industrial scale. Furthermore, a plethora of developments can be envisioned (e.g., by adding a third trifunctional component to the formulations for the synthesis of PFPE-based elastomers).

  15. Synthesis and characterization of the B3-monomer and hyperbranched poly(aryl ether ketone)s

    Institute of Scientific and Technical Information of China (English)

    Mu Jianxin; Zhang Chunling; Wang Zou; Chen Jie; Jiang Zhenhua

    2006-01-01

    Hyperbranched poly(aryl ether ketone)s were prepared by polymerization of hydroquinone(A2)and 1,3,5-tris[4-(4-fluorobenzoyl)phenoxy]benzene (B3).The gelation of hyperbranched poly(aryl ether ketone)s was effectively avoided.Hydroxyl-terminated(HPAEK-OH)and fluoro-terminated (HPAEK-F) hyperbranched poly(aryl ether ketone)s were prepared by using different A2/B3 mass ratio.The structure of the B3 monomer was confirmed by MS,1H NMR/IR.The glass transition temperatures of the HPAEK-F and HPAEK-OH are 114℃ and 162℃ respectively.Thermal stability of HPAEK-F is higher than HPAEK-OH.

  16. Synthesis of Hyperbranched Glycoconjugates by the Combined Action of Potato Phosphorylase and Glycogen Branching Enzyme from Deinococcus geothermalis

    Directory of Open Access Journals (Sweden)

    Katja Loos

    2012-02-01

    Full Text Available Potato phosphorylase is able to synthesize linear polyglucans from maltoheptaose primers. By coupling maltoheptaose to butane diamine, tris(2-aminoethylamine and amine functionalized amine functionalized poly ethyleneglycol (PEG, new primer molecules became available. The resulting di-, tri- and macro-primers were incubated with potato phosphorylase and glycogen branching enzyme from Deinococcus geothermalis. Due to the action of both enzymes, hyperbranched polyglucan arms were grown from the maltoheptaose derivatives with a maximum degree of branching of 11%. The size of the synthesized hyperbranched polyglucans could be controlled by the ratio monomer over primer. About 60%–80% of the monomers were incorporated in the glycoconjugates. The resulting hyperbranched glycoconjugates were subjected to Dynamic Light Scattering (DLS measurements in order to determine the hydrodynamic radius and it became obvious that the structures formed agglomerates in the range of 14–32 nm.

  17. 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.

  18. 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.

  19. 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.

  20. FTIR-ATR monitoring and SEC/RI/MALLS characterization of ATRP synthesized hyperbranched polyacrylates

    OpenAIRE

    Gonçalves, Miguel; Pinto, Virgínia; Dias, Rolando; Costa, Mário Rui

    2010-01-01

    This work reports the synthesis at 1 L scale of hyperbranched polyacrylates based upon acrylate/diacrylate monomers such as n-butyl acrylate (nBA)/1,6-hexanediol diacrylate (HDDA) and using atom transfer radical polymerization (ATRP). A FTIR-ATR immersion probe was used to monitor the polymerization reaction. The dynamics of the build-up of polymer structure was studied by off-line analysis of samples at different reaction times by size exclusion chromatography (SEC) with detection of refract...

  1. HYPERBRANCHED EPOXY RESINS PREPARED BY PROTON TRANSFER POLYMERIZATION FROM AN A2 + B3 SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Li-jie Ma; Hai-qiao Wang; Li fan He; Xiao-yu Li

    2011-01-01

    Epoxy-terminated hyperbranched polymers (EHBPs) were prepared by proton transfer polymerization and characterized by FT-IR, 1H-NMR and GPC. The solution and thermal properties of the uncured samples and mechanical properties of cured samples were examined. The thermo-stable products had good solubility in polar solvents, low solution viscosity and Tgs ranging from 15℃ to 33℃ depending on their molecular weights. The mechanical properties of cured films were studied and compared with those of a bisphenol-A type epoxy resin. The films of EHBPs had good impact resistance and high gloss values without sacrificing hardness and adhesion.

  2. A novel chain-extended urea containing hyperbranched polymer used as toughening modifier for epoxy resin

    Institute of Scientific and Technical Information of China (English)

    LU Shao-rong; WEI Chun; YANG Xiao-wang

    2006-01-01

    A new kind of reactive toughening accelerator for epoxy resin,amine-teminated hyperbranched polymer (H2O-NMe2) was synthesized and characterized by FT-IR spectroscopy. Dynamic mechanical analysis (DMA) was used to study the glass transition temperature (Tg),loss factor (tanδ) and activation energy (Ea) by using multiplexing frequency. The results show that the Ea at glassy relaxation process of modified system is about 70-80 kJ/mol higher than that of unmodified system,and the high modulus and good thermal properties are still maintained.

  3. Using of Hyperbranched Poly(amidoamine as Pretanning Agent for Leather

    Directory of Open Access Journals (Sweden)

    Amal Amin Ibrahim

    2013-01-01

    Full Text Available Although chrome is considered as the major tanning agent in the production of all types of hides and leather worldwide, it represents a serious source of environmental pollution. Therefore, polyamidoamine hyperbranched polymer (HPAM was involved in pretanning of the depickled hides to enhance the chromium uptake during the tanning process. The key parameters which affect the exhaustion and fixation of chrome tan including shrinkage temperature of the tanned leather were studied. The results showed a significant improvement in the chrome exhaustion, the shrinkage temperature, and the texture and softness of the leather treated by HPAM.

  4. 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.

  5. 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.

  6. Application research progress of hyperbranched polyesteramide%超支化聚酰胺酯应用研究进展

    Institute of Scientific and Technical Information of China (English)

    张新荔; 张可青

    2009-01-01

    Hyperbranched polyesteramide(PEA) was applied in many fields due to their unique structure and performances, and was one of commercialized hyperbranched polymers (HBP) at present. The application research progresses of hyperbranched PEA were reviewed in coat bonding, fibre dyeing, plastic modified and pigment dispersing. Meanwhile,the research directions of hyperbranched PEA was expected for the future.%超支化聚酰胺酯(PEA)因其独特的结构和性能特点,已成为目前商业化生产的超支化聚合物(HBP)之一,并已在许多领域中获得应用.综述了超支化PEA在涂层粘接、纤维染色、塑料改性和颜料分散等方面的应用研究进展,同时对超支化PEA今后的研究方向作了展望.

  7. Straightforward synthesis of hyperbranched polymer/graphene nanocomposites from graphite oxide via in situ grafting from approach

    Indian Academy of Sciences (India)

    Qiuhong Xu; Yiwen Gong; Yuan Fang; Guohua Jiang; Yin Wang; Xinke Sun; Rijing Wang

    2012-10-01

    The grafting of graphite oxide (GO) with cyclic ether monomers, directly affords grafting with hyperbranched polymers. The resulting nanocomposites show good solubility in the solvents of polymers, exfoliation of graphene in the polymer matrix and excellent mechanical properties and robustness under bending.

  8. 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...

  9. 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.

  10. 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)].

  11. 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.

  12. Design of amphiphilic nanocapsules based on hyperbranched star-block copolymers for the encapsulation and the controlled release of olfactory compounds

    OpenAIRE

    Ternat, Céline

    2007-01-01

    Effective encapsulation of small, volatile, weakly water-soluble molecules such as flavors and fragrances is necessary to protect them from degradation, to increase their lifetime, and to improve their water dispersion and fixation depending on the substrate of interest. The aim of this project has been to improve encapsulation and release in order to optimize the performance of fragrance molecules in water-based household (detergents, softeners, etc.) and body care applications (shampoos, lo...

  13. Hyperbranched quasi-1D nanostructures for solid-state dye-sensitized solar cells.

    Science.gov (United States)

    Passoni, Luca; Ghods, Farbod; Docampo, Pablo; Abrusci, Agnese; Martí-Rujas, Javier; Ghidelli, Matteo; Divitini, Giorgio; Ducati, Caterina; Binda, Maddalena; Guarnera, Simone; Li Bassi, Andrea; Casari, Carlo Spartaco; Snaith, Henry J; Petrozza, Annamaria; Di Fonzo, Fabio

    2013-11-26

    In this work we demonstrate hyperbranched nanostructures, grown by pulsed laser deposition, composed of one-dimensional anatase single crystals assembled in arrays of high aspect ratio hierarchical mesostructures. The proposed growth mechanism relies on a two-step process: self-assembly from the gas phase of amorphous TiO2 clusters in a forest of tree-shaped hierarchical mesostructures with high aspect ratio; oriented crystallization of the branches upon thermal treatment. Structural and morphological characteristics can be optimized to achieve both high specific surface area for optimal dye uptake and broadband light scattering thanks to the microscopic feature size. Solid-state dye sensitized solar cells fabricated with arrays of hyperbranched TiO2 nanostructures on FTO-glass sensitized with D102 dye showed a significant 66% increase in efficiency with respect to a reference mesoporous photoanode and reached a maximum efficiency of 3.96% (among the highest reported for this system). This result was achieved mainly thanks to an increase in photogenerated current directly resulting from improved light harvesting efficiency of the hierarchical photoanode. The proposed photoanode overcomes typical limitations of 1D TiO2 nanostructures applied to ss-DSC and emerges as a promising foundation for next-generation high-efficiency solid-state devices comprosed of dyes, polymers, or quantum dots as sensitizers.

  14. Incorporation of Hyperbranched Supramolecules into Nafion Ionic Domains via Impregnation and In-Situ Photopolymerization

    Directory of Open Access Journals (Sweden)

    Hiruto Kudo

    2011-11-01

    Full Text Available Nafion membranes were impregnated with photocurable supramolecules, viz., hyperbranched polyester having pendant functional carboxylic acid groups (HBPEAc-COOH by swelling in methanol and subsequently photocured in-situ after drying. Structure-property relationships of the HBPEAc-COOH impregnated Nafion membranes were analyzed on the basis of Fourier transform infrared (FTIR spectroscopy, solid-state nuclear magnetic resonance (SSNMR and dynamic mechanical analysis (DMA. FTIR and SSNMR investigations revealed that about 7 wt % of HBPEAc-COOH was actually incorporated into the ionic domains of Nafion. The FTIR study suggests possible complexation via inter-species hydrogen bonding between the carboxylic groups of HBPEAc-COOH and the sulfonate groups of Nafion. The α-relaxation peak corresponding to the glass transition temperature of the ionic domains of the neat Nafion-acid form was found to increase from ~100 to ~130 °C upon impregnation with enhanced modulus afforded by the cured polyester network within the ionic domains. The AC impedance fuel cell measurement of the impregnated membrane exhibited an increasing trend of proton conductivity with increasing temperature, which eventually surpassed that of neat Nafion above 100 °C. Of particular importance is that the present paper is the first to successfully incorporate polymer molecules/networks into the Nafion ionic domains by means of impregnation with hyperbranched supramolecules followed by in-situ photopolymerization.

  15. Succinate Functionalization of Hyperbranched Polyglycerol-Coated Magnetic Nanoparticles as a Draw Solute During Forward Osmosis.

    Science.gov (United States)

    Yang, Hee-Man; Choi, Hye Min; Jang, Sung-Chan; Han, Myeong Jin; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo

    2015-10-01

    Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPG-MNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes.

  16. Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications.

    Science.gov (United States)

    Robinson, Joshua W; Zhou, Yan; Bhattacharya, Priyanka; Erck, Robert; Qu, Jun; Bays, J Timothy; Cosimbescu, Lelia

    2016-01-01

    We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acids (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated an improved viscosity index and reduced friction coefficient, validating the basic approach.

  17. Magnetorheological fluids based on a hyperbranched polycarbosilane matrix and iron microparticles

    Science.gov (United States)

    Vasiliev, V. G.; Sheremetyeva, N. A.; Buzin, M. I.; Turenko, D. V.; Papkov, V. S.; Klepikov, I. A.; Razumovskaya, I. V.; Muzafarov, A. M.; Kramarenko, E. Yu

    2016-05-01

    Magnetorheological fluids (MFs) based on hyperbranched polycarbosilanes as a carrier medium and micron-sized carbonyl iron particles as filler have been synthesized for the first time. Their magnetorheological (MR) behavior has been studied in steady-state flow regime and under dynamic torsion oscillations on a commercial rheometer. At zero magnetic field, in spite of a rather high molecular mass, the hyperbranched polymers as well as their magnetic compositions with up to 72 mass% of magnetic filler demonstrate Newtonian behavior, and their viscosity considerably increases with magnetic filler content. In magnetic fields MFs show a huge MR response. Namely, in steady-state flow experiments a five orders of magnitude increase in viscosity was observed accompanied by magnetic-field-induced well-pronounced non-Newtonian behavior and a non-zero yield stress. Dynamic experiments demonstrate the transition from liquid-like to solid-like behavior of MFs with a large increase in both the storage and loss moduli under application of a magnetic field. In magnetic fields, the rheological behavior of the obtained MF resembles that of soft MR elastomers being mainly determined by the magnetic particle network formed due to magnetic interactions. In particular, like MR elastomers the MFs exhibit the Payne effect, i.e. dependence of the dynamic modulus on the strain amplitude.

  18. Release of Ftorafur from pH-sensitive hydrogels with hyperbranched poly(4-vinylbenzyl chloride) moieties

    International Nuclear Information System (INIS)

    Drug release behavior of a hydrogel is related to its transport mechanism, which is dominated by structure of the hydrogel. Therefore, we prepared pH-sensitive poly(4-vinylpyridine) (P4VP) hydrogels with hyperbranched poly(4-vinylbenzyl chloride) (PVBC; Mn = 2391 g/mol, PDI = 1.87, the minimum percent linearity = 12.4%) moieties (P4VP-PVBC) by atom transfer radical polymerizations (ATRP) in two steps. A PVBC moiety provides the hydrogel with a microenvironment, which may encapsulate guest molecules like drug. The presence of the microenvironment could affect drug transport in the hydrogel matrices. To understand this, we used Ftorafur as drug molecule, and investigated release behavior of the P4VP-based hydrogels. Diffusion and transport mechanism of Ftorafur in the P4VP-based hydrogels was analyzed by early-time and late-time approximation diffusion coefficients. It was found that the transport behavior of Ftorafur was related to the presence of the PVBC moiety and external pH. The presence of the PVBC moiety could sustain release of Ftorafur. - Highlights: ► pH-sensitive P4VP hydrogels with hyperbranched PVBC moieties was prepared by ATRP. ► The PVBC moieties may encapsulate guest molecules like drug. ► Diffusion and transport mechanism of Ftorafur in the P4VP hydrogels was analyzed. ► The presence of PVBC moieties could sustain release of Ftorafur from the hydrogel.

  19. Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications

    Science.gov (United States)

    Robinson, Joshua W.; Zhou, Yan; Bhattacharya, Priyanka; Erck, Robert; Qu, Jun; Bays, J. Timothy; Cosimbescu, Lelia

    2016-01-01

    We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acids (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated an improved viscosity index and reduced friction coefficient, validating the basic approach.

  20. Synthesis of New Hyperbranched α-Glucans from Sucrose by Lactobacillus reuteri 180 Glucansucrase Mutants.

    Science.gov (United States)

    Meng, Xiangfeng; Dobruchowska, Justyna M; Pijning, Tjaard; Gerwig, Gerrit J; Dijkhuizen, Lubbert

    2016-01-20

    α-Glucans produced by glucansucrase enzymes of lactic acid bacteria attract strong attention as novel ingredients and functional biopolymers in the food industry. In the present study, α-helix 4 amino acid residues D1085, R1088, and N1089 of glucansucrase GTF180 of Lactobacillus reuteri 180 were targeted for mutagenesis both jointly and separately. Analysis of the mutational effects on enzyme function revealed that all D1085 and R1088 mutants catalyzed the synthesis of hyperbranched α-glucans with 15-22% branching (α1→3,6) linkages, compared to 13% in the wild-type GTF180. In addition, besides native (α1→6) and (α1→3) linkages, all of the mutations introduced a small amount of (α1→4) linkages (5% at most) in the polysaccharides produced. We conclude that α-helix 4 residues, especially D1085 and R1088, constituting part of the +2 acceptor binding subsite, are important determinants for the linkage specificity. The new hyperbranched α-glucans provide very interesting structural diversities and may find applications in the food industry.

  1. Controlled synthesis of hyper-branched inorganic nanocrystals withrich three-dimensional structures

    Energy Technology Data Exchange (ETDEWEB)

    Kanaras, Antonios G.; Sonnichsen, Carsten; Liu, Haitao; Alivisatos, A. Paul

    2005-07-27

    Studies of crystal growth kinetics are tightly integrated with advances in the creation of new nanoscale inorganic building blocks and their functional assemblies 1-11. Recent examples include the development of semiconductor nanorods which have potential uses in solar cells 12-17, and the discovery of a light driven process to create noble metal particles with sharp corners that can be used in plasmonics 18,19. In the course of studying basic crystal growth kinetics we developed a process for preparing branched semiconductor nanocrystals such as tetrapods and inorganic dendrimers of precisely controlled generation 20,21. Here we report the discovery of a crystal growth kinetics regime in which a new class of hyper-branched nanocrystals are formed. The shapes range from 'thorny balls', to tree-like ramified structures, to delicate 'spider net'-like particles. These intricate shapes depend crucially on a delicate balance of branching and extension. The multitudes of resulting shapes recall the diverse shapes of snowflakes 22.The three dimensional nature of the branch points here, however, lead to even more complex arrangements than the two dimensionally branched structures observed in ice. These hyper-branched particles not only extend the available three-dimensional shapes in nanoparticle synthesis ,but also provide a tool to study growth kinetics by carefully observing and modeling particle morphology.

  2. SYNTHESIS AND MAGNETIC PROPERTIES OF COMPLEXES OF A CONJUGATED HYPERBRANCHED POLYMER CONTAINING BITHIAZOLE RINGS

    Institute of Scientific and Technical Information of China (English)

    Neng-wen Ding; Wei-lin Sun; Yan Lin; Zhi-quan Shen

    2012-01-01

    A novel conjugated hyperbranched polymer containing bithiazole rings (PBTADB) was synthesized by polycondensation of 1,3,5-benzenetricarboxaldehyde and 2,2′-diamino-4,4′-bithiazole (DABT).The structure of the hyperbranched polymer was confirmed by FT-IR and 1H-NMR.PBTADB dissolved in organic polar solvents such as DMSO and NMP.Bithiazole rings were introduced to provide bidentate N-donor sites for binding metal ions.The metal complexes were prepared by chelation of the polymer with Co2+ and Sm3+.The magnetic behavior of coordination compounds was measured as a function of magnetic field strength (0-4.8 × l06 A/m) at 5 K and as a function of temperature (5-300 K) at magnetic field strength of 2.4 × 106 A/m.The magnetic hysteresis loops of PBTADB-Sm3+ and PBTADB-Co2+ showed the typical ‘S' shape at 5 K with the Curie-Weiss temperature Tθ =96 K and 41 K respectively.The results show that they exhibit properties of soft ferromagnetic materials.

  3. Hyperbranched Aliphatic Polyester Modified Activated Carbon Particles with Homogenized Surface Groups

    Science.gov (United States)

    Liu, Peng; Zhang, Liuxue

    The hyperbranched aliphatic polyester grafted activated carbon (HAPE-AC), was successfully prepared by the simple "one-pot" method. The surface functional groups of commercial activated carbon particles were homogenized to hydroxyl groups by being oxidized with nitric acid and then reduced with lithium tetrahydroaluminate (LiAlH4) at first. Secondly, the surface hydroxyl groups were used as the active sites for the solution polycondensation of the AB2 monomer, 2, 2-bis(hydroxymethyl)propionic acid (bis-MPA), with the catalysis of p-toluenesulfonic acid (p-TSA). The homogenization of the surface groups of the activated carbon particles and the graft polymerization of the hyperbranched aliphatic polyester were investigated by X-ray photoelectron spectroscopy (XPS) technique. The products were also characterized with Fourier transform infrared (FT-IR) and scanning electron microscope (SEM). The competitive adsorption properties of the products toward the heavy metal ions (Cu(II), Hg(II), Zn(II), and Cd(II)) also proved the translations of the surface groups.

  4. Synthesis and intrinsic blue fluorescence study of hyperbranched poly(ester-amide-ether)

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of hyperbranched poly(ester-amide-ether)s (H-PEAEs) were synthesized via the A2+CB3 approach by the self-transesterification of ethyl ester-amide-ethers end-capped with three hydroxyl groups and ethyl ester group at two terminals.The molecular structures were characterized with 1H NMR and FT-IR spectroscopy.The number average molecular weights were estimated by GPC analysis to possess bimodal wide distribution from 1.57 to 2.09.The strong inherent blue fluorescence was observed at 330 nm for excitation and 390 nm for emission.Moreover,the emission intensity and fluorescence quantum yield increased along with the incorporated ether chain length,as well as almost linearly with the H-PEAE concentration in an aqueous solution.For comparing the fluorescence performance,the linear poly(ester-amide-ether) (L-PEAE) and hyperbranched poly(ester-amide) (H-PEA) were synthesized.The results showed that the coexistence of ether bond and carboxyl group in the molecular chain was essential for generating the strong fluorescence.However,the compact backbone of H-PEAE would be propitious to the enhancement of fluorescence properties.

  5. Hard and flexible nanocomposite coatings using nanoclay-filled hyperbranched polymers.

    Science.gov (United States)

    Fogelström, Linda; Malmström, Eva; Johansson, Mats; Hult, Anders

    2010-06-01

    The combination of hardness, scratch resistance, and flexibility is a highly desired feature in many coating applications. The aim of this study is to achieve this through the introduction of an unmodified nanoclay, montmorillonite (Na(+)MMT), in a polymer resin based on the hyperbranched polyester Boltorn H30. Smooth and transparent films were prepared from both the neat and the nanoparticle-filled hyperbranched resins. X-ray diffraction (XRD) and transmission electron microscopy (TEM) corroborated a mainly exfoliated structure in the nanocomposite films, which was also supported by results from dynamic mechanical analysis (DMA). Furthermore, DMA measurements showed a 9-16 degrees C increase in Tg and a higher storage modulus-above and below the T(g)-both indications of a more cross-linked network, for the clay-containing film. Thermogravimetric analysis (TGA) demonstrated the influence of the nanofiller on the thermal properties of the nanocomposites, where a shift upward of the decomposition temperature in oxygen atmosphere is attributed to the improved barrier properties of the nanoparticle-filled materials. Conventional coating characterization methods demonstrated an increase in the surface hardness, scratch resistance and flexibility, with the introduction of clay, and all coatings exhibited excellent chemical resistance and adhesion.

  6. Drug release property of a pH-responsive double-hydrophilic hyperbranched graft copolymer

    Institute of Scientific and Technical Information of China (English)

    SUN XiaoYi; ZHOU YongFeng; YAN DeYue

    2009-01-01

    In this paper, we report the synthesis and self-assembly of double-hydrophilie hyperbranched graft copolymers of HPG-g-PDMAEMA, which consist of a hyperbranched polyglycerol (HPG) core and several grafted poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) arms. HPG was synthesized by cationic polymerization. Then HPG-Br macroinitiator was obtained by esterification of HPG with 2-bromoisobutyryl bromide, which was subsequently used in the preparation of HPG-g-PDMAEMA graft copolymers through atom transfer radical polymerization (ATRP) of DMAEMA monomers. The molecular structures were studied by 1H NMR arid GPC. The pyrene-based fluorescent probe method, 1H NMR and DLS were used to study the self-assembly behavior of HPG-g-PDMAEMA. The drug loading and pH-responsive release properties of HPG-g-PDMAEMA were also investigated by using coumarin 102 as a model drug. The results show that the HPG-g-PDMAEMA micelles can continuously release and re-encapsulate coumarin 102 as the pH continuously changes from 11.5 to 2.5; however, this process is not totally reversible.

  7. Drug release property of a pH-responsive double-hydrophilic hyperbranched graft copolymer

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, we report the synthesis and self-assembly of double-hydrophilic hyperbranched graft copolymers of HPG-g-PDMAEMA, which consist of a hyperbranched polyglycerol (HPG) core and several grafted poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) arms. HPG was synthesized by cationic polymerization. Then HPG-Br macroinitiator was obtained by esterification of HPG with 2-bromoisobutyryl bromide, which was subsequently used in the preparation of HPG-g-PDMAEMA graft copolymers through atom transfer radical polymerization (ATRP) of DMAEMA monomers. The molecular structures were studied by 1H NMR and GPC. The pyrene-based fluorescent probe method, 1H NMR and DLS were used to study the self-assembly behavior of HPG-g-PDMAEMA. The drug loading and pH-responsive release properties of HPG-g-PDMAEMA were also investigated by using coumarin 102 as a model drug. The results show that the HPG-g-PDMAEMA micelles can continuously release and re-encapsulate coumarin 102 as the pH continuously changes from 11.5 to 2.5; however, this process is not totally reversible.

  8. Synthesis and swelling behavior of polyurethane networks based on hyperbranched polymer

    Directory of Open Access Journals (Sweden)

    Džunuzović Jasna V.

    2011-01-01

    Full Text Available A series of six polyurethane (PU networks was synthesized from BoltornR hydroxy-functional hyperbranched polyester (HBP of the second pseudo generation as a crosslinking agent, α,ω- dihydroxy-(ethylene oxide-poly(dimethylsiloxane-ethylene oxide (EO-PDMS-EO and 4,4’- methylenediphenyl diisocyanate, by a two-step polymerization in solution. Each sample of the prepared PUs had different EO-PDMS-EO content. The chemical structure of the synthesized networks was analyzed by FTIR spectroscopy. The influence of the EO-PDMS-EO content and type of the solvent on the swelling behavior of the PUs in 2-propanol and toluene was investigated. During the swelling measurements certain amount of sol fractions was extracted from the PUs by solvents. According to the 1H NMR results, sol fractions are mainly composed of the soluble hyperbranched PU, formed during the polymerization by partial modification of the end hydroxyl groups of HBP with NCO-terminated prepolymer synthesized in the first step of the reaction. Chains of the so reacted prepolymer can then fold back and form cyclic products by reaction of the free -NCO group from the NCO-terminated prepolymer with free -OH group of HBP. As the EO-PDMS-EO content increases the amount of the sol fractions and swelling degree also increased, indicating that networks with lower EO-PDMS-EO content are more crosslinked and have higher solvent resistance.

  9. Effect of support structure on CO2 adsorption properties of pore-expanded hyperbranched aminosilicas

    KAUST Repository

    Drese, Jeffrey H.

    2012-03-01

    Hyperbranched aminosilica (HAS) CO 2 adsorbents are prepared by the ring-opening polymerization of aziridine from SBA-15 mesoporous silica, as in the original synthesis of HAS materials, as well as over an array of new support materials with substantially larger average pore diameters to elucidate the effect of support porosity on final adsorbent properties. Pore-expanded hyperbranched aminosilica (PEHAS) CO 2 adsorbents are prepared from several different pore-expanded, ordered mesoporous silicas including pore-expanded SBA-15, mesocellular foam, and a large-pore commercial silica. The effect of the nature of the silica support is determined by examining the degree of aziridine polymerization and the CO 2 adsorption kinetics and capacities of the resulting organic/inorganic hybrid materials. Comparisons are made to non-pore-expanded SBA-15 based HAS adsorbents, reported previously, where pores become blocked at higher amine loadings. The PEHAS materials unexpectedly possess lower amine loadings than the previously reported HAS materials and do not exhibit pore blocking. The use of acetic acid as a catalyst during PEHAS synthesis only marginally increases amine loading. The adsorption kinetics of PEHAS adsorbents are similar to HAS adsorbents with low amine loadings and do not show the detrimental effects of pore-blocking. However, the inability to synthesize PEHAS adsorbents with high amine loadings via this approach limits the total amount of CO 2 captured per gram of material, compared to HAS adsorbents with high amine loadings. © 2011 Elsevier Inc. All rights reserved.

  10. Thermodynamics of coil-hyperbranched poly(styrene-b-acrylated epoxidized soybean oil) block copolymers

    Science.gov (United States)

    Lin, Fang-Yi; Hohmann, Austin; Hernández, Nacú; Cochran, Eric

    Here we present the phase behavior of a new type of coil-hyperbranched diblock copolymer: poly(styrene- b-acrylated epoxidized soybean oil), or PS-PAESO. PS-PAESO is an example of a biorenewable thermoplastic elastomer (bio-TPE). To date, we have shown that bio-TPEs can be economical commercial substitutes for their petrochemically derived analogues--such as poly(styrene- b-butadiene- b-styrene) (SBS)--in a range of applications including pressure sensitive adhesives and bitumen modification. From a polymer physics perspective, PS-PAESO is an interesting material in that it couples a linear coil-like block with a highly branched block. Thus in contrast to the past five decades of studies on linear AB diblock copolymers, coil-hyperbranched block copolymers are relatively unknown to the community and can be expected to deviate substantially from the standard ``universal'' phase behavior in the AB systems. To explore these new materials, we have constructed a library of PS-PAESO materials spanning a range of molecular weight and composition values. The phase transition behavior and the morphology information will be interpreted by isochronal temperature scanning in dynamic shear rheology, small angle X-ray scattering and the corresponding transmission electron microscopy.

  11. Synthesis and Gas Transport Properties of Hyperbranched Polyimide–Silica Hybrid/Composite Membranes

    Directory of Open Access Journals (Sweden)

    Masako Miki

    2013-12-01

    Full Text Available Hyperbranched polyimide–silica hybrids (HBPI–silica HBDs and hyperbranched polyimide–silica composites (HBPI–silica CPTs were prepared, and their general and gas transport properties were investigated to clarify the effect of silica sources and preparation methods. HBPI–silica HBDs and HBPI–silica CPTs were synthesized by two-step polymerization of A2 + B3 monomer system via polyamic acid as precursor, followed by hybridizing or blending silica sources. Silica components were incorporated by the sol-gel reaction with tetramethoxysilane (TMOS or the addition of colloidal silica. In HBPI-silica HBDs, the aggregation of silica components is controlled because of the high affinity of HBPI and silica caused by the formation of covalent bonds between HBPI and silica. Consequently, HBPI-silica HBDs had good film formability, transparency, and mechanical properties compared with HBPI-silica CPTs. HBPI-silica HBD and CPT membranes prepared via the sol-gel reaction with TMOS showed specific gas permeabilities and permselectivities for CO2/CH4 separation, that is, both CO2 permeability and CO2/CH4 selectivity increased with increasing silica content. This result suggests that gas transport can occur through a molecular sieving effect of the porous silica network derived from the sol-gel reaction and/or through the narrow interfacial region between the silica networks and the organic matrix.

  12. Cross-linking high-k fluoropolymer gate dielectrics enhances the charge mobility in rubrene field effect transistors

    Science.gov (United States)

    Adhikari, Jwala; Gadinski, Matthew; Wang, Qing; Gomez, Enrique

    2015-03-01

    Polymer dielectrics are promising materials where the chemical flexibility enables gate insulators with desired properties. For example, polar groups can be introduced to enhance the dielectric constant, although fluctuations in chain conformations at the semiconductor-dielectric interface can introduce energetic disorder and limit charge mobilities in thin-film transistors. Here, we demonstrate a photopatternable high-K fluoropolymer, poly(vinylidene fluoride-bromotrifluoroethylene) P(VDF-BTFE), with a dielectric constant between 8 and 11. The bromotrifluoroethylene moiety enables photo-crosslinking and stabilization of gate insulator films while also significantly enhancing the population of trans torsional conformations of the chains. Using rubrene single crystals as the active layer, charge mobilities exceeding 10 cm2/Vs are achieved in thin film transistors with cross-linked P(VDF-BTFE) gate dielectrics. We hypothesize that crosslinking reduces energetic disorder at the dielectric-semiconductor interface by suppressing segmental motion and controlling chain conformations of P(VDF-BTFE), thereby leading to approximately a three-fold enhancement in the charge mobility of rubrene thin-film transistors over devices incorporating uncross-linked dielectrics or silicon oxide. Center for Flexible Electronic, Penn State; The Dow Chemical Company.

  13. Evaluating the impact of a fluoropolymer plant on a river macrobenthic community by a combined chemical, ecological and genetic approach.

    Science.gov (United States)

    Rusconi, Marianna; Marziali, Laura; Stefani, Fabrizio; Valsecchi, Sara; Bettinetti, Roberta; Mazzoni, Michela; Rosignoli, Federica; Polesello, Stefano

    2015-12-15

    Effect-based monitoring is a recommended approach suggested in European Guidelines to assess the response of ecosystem affected by a pollution source, considering the effects at community, population, individual but also at suborganism level. A combined chemical, ecological and genetic approach was applied in order to assess the impact of a fluoropolymer plant on the macrobenthic community of the Northern Italian river Bormida (Piedmont region). The macrobenthic community living downstream of the industrial discharge was chronically exposed to a mixture of perfluoroalkyl substances (PFAS), with perfluorooctanoic acid as the main compound, at concentrations up to several μgL(-1). Ecological assessment proved that the downstream community was not substantially different from that living upstream of the pollution source. The impact on community is not quantifiable with the traditional monitoring methods used for ecological classification under European regulation because macrobenthic communities showed only slight differences in their structure. In order to highlight effects on genetic variability of the native population, a subcellular analysis by using the AFLP (Amplified Fragment Length Polymorphism) genetic technique was applied to genotype of individuals of a selected species (Hydropsyche modesta, Trichoptera) collected in the two sampling sites. Percentage of variation between the two populations was 6.8%, a threshold compatible with a genetic drift induced in the downstream population. The genetic study carried out in field identified a significant divergence between exposed and non-exposed populations, but at present it is not possible to associate this divergence to a specific effect induced by PFAS.

  14. 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...

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. 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...

  20. 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

  1. 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.

  2. 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.

  3. 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)

  4. Effect of Hyperbranched Polyester on Modification of Epoxy Resins Cured with Anhydride

    Institute of Scientific and Technical Information of China (English)

    Xiu Xia WANG; Zhi Gang JIANG; Yi Feng ZHANG

    2006-01-01

    The synthesis and characterization of hyperbranched polyester (HBP) with different molecular weight are studied. The effect of HBP on the modification of epoxy resins cured with anhydride is mainly discussed. The characteristics of HBP and the morphologies of cured system are determined by nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and scanning electron microscope (SEM). The impact strength of cured system is detected and Fourier transform infrared (FTIR) measurements were used to pursue the curing process. The investigation shows that HBP can improve the toughness by forming copolymer networks between epoxy resins, HBP and anhydride. Moreover, when the molecular weight of HBP is 1342g/mol the toughening effect is the best, and the changes of toughness are small with the increase of molecular weight of HBP to 3500 g/mol.

  5. An efficient nonviral gene-delivery vector based on hyperbranched cationic glycogen derivatives

    Directory of Open Access Journals (Sweden)

    Liang X

    2014-01-01

    Full Text Available Xuan Liang,1,* Xianyue Ren,2,* Zhenzhen Liu,1 Yingliang Liu,1 Jue Wang,2 Jingnan Wang,2 Li-Ming Zhang,1 David YB Deng,2 Daping Quan,1 Liqun Yang1 1Institute of Polymer Science, School of Chemistry and Chemical Engineering, Key Laboratory of Designed Synthesis and Application of Polymer Material, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-Sen University, Guangzhou, People's Republic of China; 2Research Center of Translational Medicine, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, People's Republic of China *Both these authors contributed equally to this work Background: The purpose of this study was to synthesize and evaluate hyperbranched cationic glycogen derivatives as an efficient nonviral gene-delivery vector. Methods: A series of hyperbranched cationic glycogen derivatives conjugated with 3-(dimethylamino-1-propylamine (DMAPA-Glyp and 1-(2-aminoethyl piperazine (AEPZ-Glyp residues were synthesized and characterized by Fourier-transform infrared and hydrogen-1 nuclear magnetic resonance spectroscopy. Their buffer capacity was assessed by acid–base titration in aqueous NaCl solution. Plasmid deoxyribonucleic acid (pDNA condensation ability and protection against DNase I degradation of the glycogen derivatives were assessed using agarose gel electrophoresis. The zeta potentials and particle sizes of the glycogen derivative/pDNA complexes were measured, and the images of the complexes were observed using atomic force microscopy. Blood compatibility and cytotoxicity were evaluated by hemolysis assay and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, respectively. pDNA transfection efficiency mediated by the cationic glycogen derivatives was evaluated by flow cytometry and fluorescence microscopy in the 293T (human embryonic kidney and the CNE2 (human nasopharyngeal carcinoma cell lines. In vivo delivery of pDNA in model animals (Sprague Dawley

  6. Surface modification of multi-wall carbon nanotube with ultraviolet-curable hyperbranched polymer

    International Nuclear Information System (INIS)

    Surface modification is a general and efficient approach to improve the compatibility of carbon nanotube (CNT) with various matrixes. Here we report the modification of multi-wall carbon nanotube (MWCNT) with hyperbranched polymer which contains UV reactive functional groups. The modification promotes the incorporation of CNT into UV-curable resin, and when cured under UV irradiation to form a homogeneous film, the CNT will be chemically bonded with the matrix by crosslinking photopolymerization. For the unique mechanical properties of CNT, the mechanical properties of the cured MWCNT/UV-curable resin film were greatly improved compared with pure resin film as indicated by the increasing of Young's modulus, tensile strength, and toughness

  7. The Time Evolution of the Surface Segregation of Hyperbranched Molecules from a Linear Matrix

    Science.gov (United States)

    Swader, Onome; Dadmun, Mark; Hutchings, Lian; Thompson, Richard

    2010-03-01

    Modification of a surface by the selective surface segregation of an additive in a mixture is a process with many commercial applications including biocompatibility, wettability, and anti-fouling in coatings. In a blend of branched and linear polymers, there exists an entropic driving force for the selective surface segregation of the branched polymer. Unfortunately, a systematic study of the impact of the branched copolymer structure on the dynamics and thermodynamics of this surface segregation is not currently available. Neutron reflectivity experiments that seek to fill this void have been completed and will be discussed. High molecular weight poly(styrene) (PS) hyperbranched molecules, hypermacs (HM) and dendrimacs (DM), with 10 % HM or DM and 90 % deuterated PS are the model systems studied. Reflectivity profiles for all blends were obtained as a function of annealing time from 30 minutes up to 48 hours.

  8. Non-enzymatic glucose biosensor based on hyperbranched pine-like gold nanostructure.

    Science.gov (United States)

    Heli, H; Amirizadeh, O

    2016-06-01

    Hyperbranched pine-like gold nanostructure was electrodeposited on the polycrystalline gold surface at 0 mV (vs. AgCl) with the assistance of histidine as a soft template. The nanostructure was then applied as a highly sensitive nonenzymatic sensor for glucose. The catalytic activity and sensitivity of the gold nanostructure toward the electrooxidation of glucose was excellent without surface fouling and deterioration effects. The current related to the oxidation of glucose rapidly and linearly depended on its concentration with a sensitivity of 776.8 μA cm(-2)mmol(-1)dm(3), a detection limit of 3.39 μmol dm(-3) with a relative standard deviation of 2.32%. PMID:27040206

  9. Reaction and characterization of crosslinking hyperbranched poly(amine-ester) with succine anhydride

    Institute of Scientific and Technical Information of China (English)

    XIAO Ling; WEI Xiuzhen; ZHU Baoku

    2007-01-01

    Basing on hydroxyl terminated hyperbranched poly(amine-ester)s (HPAEs),the cross-linking reactions and preparation of ester-crosslinked HPAE films were investigated using succine anhydride (SA) as crosslink reagent.It was proved that the cross-linking reaction between HPAE and SA followed a two-step mechanism.This mechanism provides an efficient route to prepare HPAE/SA cross-linked films,in which,the precursor films were prepared by casting HPAE/SA solution at a lower temperature,and then curing the films at a higher temperature.By varying SA content,the solid HPAE/SA films with different cross-linking degrees were prepared successfully.The highest tensile strength of the cross-linked film could reach 59.60 MPa.With all water contact angle smaller than 74.3°,the crosslinked films demonstrated good hydrophilic properties.

  10. Hyperbranched Acrylated Aromatic Polyester Used as a Modifier in UV-Curable Epoxy Acrylate Resins

    Institute of Scientific and Technical Information of China (English)

    KOU,Hui-Guang; ASIF,Anila; SHI,Wen-Fang

    2003-01-01

    The viscosity, the shrinkage degree and the photoplymerization rate of the epoxy acrylate (EB600 ) blended with hyperbranched acrylated aromatic polyester ( HAAPE ) were investigated. The addition of HAAPE into EB600 largely reduces the viscosity of the blend formulation and the shrinkage degree. For example, EB600resin with 50% weight fraction of HAAPE has the 1250 cps of the viscosity and 2.0% of shrinkage degree, while the pure EB600 resin has 3000 cps of the viscosity and 10.5% of shrinkage degree. The photopolymerization rate of the rein is also promoted by HAAPE addition. The good miscibility between HAAPE and EB600 was also observed from the dynamic mechanical analysis. The tensile, flexural and compressive strength, and the thermal properties of the UVcured films are greatly improved.

  11. Synthesis and liquid crystalline properties of hyperbranched aromatic polyesters consisting of azoxybenzene mesogens and polymethylene spacers

    International Nuclear Information System (INIS)

    A new series of hyperbranched aromatic polyesters containing azoxybenzene mesogens and polymethylene spacers were prepared by polymerizing AB2 type monomers that have the isophthaloyl dicarboxylic acid terminal at one end and the p-oxyphenol terminal at the other end. The monomers contain a built-in azoxybenzene mesogen that is linked to the terminal groups through polymethylene spacers. The polyesters prepared were characterized by solution viscosity , differential scanning calorimetry, X-ray diffractometry and polarizing microscopy. All of the polyesters were found to be thermotropic (nematic). Their glass-transition temperatures and mesophase temperature ranges were very sensitive to the length of the two spacers existing in the repeating unit. The degree of branching of one of the polyesters was determined by the NMR spectroscopy and found to be 0.56

  12. The effects of hyperbranched poly(siloxysilane)s on conductive polymer aluminum solid electrolytic capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Nogami, Katsunori [Graduate School of Tokyo Institute Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Nippon Chemi-Con Co., 185-1, Marunouchi, Yabuki-machi, Nishi-Shirakawa-gun, Fukushima 969-0235 (Japan); Sakamoto, Kiyoshi [Nippon Chemi-Con Co., 185-1, Marunouchi, Yabuki-machi, Nishi-Shirakawa-gun, Fukushima 969-0235 (Japan); Hayakawa, Teruaki; Kakimoto, Masa-aki [Graduate School of Tokyo Institute Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2007-04-15

    An aluminum solid electrolytic capacitor, using poly-(3,4-ethylenedioxythiophene) (PEDOT) as a counter electrode, was prepared with hyperbranched poly(siloxysilane)s (HBPSi) that has a large number of vinyl groups to improve the interfacial properties between aluminum oxide and PEDOT. Capacitance and equivalent series resistance (Rs) were significantly improved compared to untreated oxide film and vinyl terminated polydimethylsiloxane coated interfaces. From electrochemical measurement of the withstand voltage, damage to the oxide film from chemical polymerization of PEDOT was less with the HBPSi treatment. Frequency characteristics and electrical conductivity measurements of the polymer indicated that the resistance inside the etched porous layer was greatly reduced. These results show that the HBPSi pre-coating layer inhibited degradation of the oxide film by chemical polymerization of PEDOT and the conductivity of PEDOT in the etched porous oxide layer, and also enlarges the contact area by improving interfacial adhesion. (author)

  13. Negatively Charged Hyperbranched Polyglycerol Grafted Membranes for Osmotic Power Generation from Municipal Wastewater

    KAUST Repository

    Li, Xue

    2015-11-18

    Osmotic power holds great promise as a clean, sustainable and largely unexploited energy resource. Recent membrane development for pressure-retarded osmosis (PRO) is making the osmotic power generation more and more realistic. However, severe performance declines have been observed because the porous layer of PRO membranes is fouled by the feed stream. To overcome it, a negatively charged antifouling PRO hollow fiber membrane has been designed and studied in this work. An antifouling polymer, derived from hyperbranched polyglycerol and functionalized by α-lipoic acid and succinic anhydride, was synthesized and grafted onto the polydopamine (PDA) modified poly(ether sulfone) (PES) hollow fiber membranes. In comparison to unmodified membranes, the charged hyperbranched polyglycerol (CHPG) grafted membrane is much less affected by organic deposition, such as bovine serum albumin (BSA) adsorption, and highly resistant to microbial growths, demonstrated by E. coli adhesion and S. aureus attachment. CHPG-g-TFC was also examined in PRO tests using a concentrated wastewater as the feed. Comparing to the plain PES-TFC and non-charged HPG-g-TFC, the newly developed membrane exhibits not only the smallest decline in water flux but also the highest recovery rate. When using 0.81 M NaCl and wastewater as the feed pair in PRO tests at 15 bar, the average power density remains at 5.6 W/m2 in comparison to an average value of 3.6 W/m2 for unmodified membranes after four PRO runs. In summary, osmotic power generation may be sustained by properly designing and anchoring the functional polymers to PRO membranes.

  14. Negatively charged hyperbranched polyglycerol grafted membranes for osmotic power generation from municipal wastewater.

    Science.gov (United States)

    Li, Xue; Cai, Tao; Chen, Chunyan; Chung, Tai-Shung

    2016-02-01

    Osmotic power holds great promise as a clean, sustainable and largely unexploited energy resource. Recent membrane development for pressure-retarded osmosis (PRO) is making the osmotic power generation more and more realistic. However, severe performance declines have been observed because the porous layer of PRO membranes is fouled by the feed stream. To overcome it, a negatively charged antifouling PRO hollow fiber membrane has been designed and studied in this work. An antifouling polymer, derived from hyperbranched polyglycerol and functionalized by α-lipoic acid and succinic anhydride, was synthesized and grafted onto the polydopamine (PDA) modified poly(ether sulfone) (PES) hollow fiber membranes. In comparison to unmodified membranes, the charged hyperbranched polyglycerol (CHPG) grafted membrane is much less affected by organic deposition, such as bovine serum albumin (BSA) adsorption, and highly resistant to microbial growths, demonstrated by Escherichia coli adhesion and Staphylococcus aureus attachment. CHPG-g-TFC was also examined in PRO tests using a concentrated wastewater as the feed. Comparing to the plain PES-TFC and non-charged HPG-g-TFC, the newly developed membrane exhibits not only the smallest decline in water flux but also the highest recovery rate. When using 0.81 M NaCl and wastewater as the feed pair in PRO tests at 15 bar, the average power density remains at 5.6 W/m(2) in comparison to an average value of 3.6 W/m(2) for unmodified membranes after four PRO runs. In summary, osmotic power generation may be sustained by properly designing and anchoring the functional polymers to PRO membranes. PMID:26630043

  15. Poly(urethane-siloxanes based on hyperbranched polyester as crosslinking agent: Synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Pergal Marija V.

    2012-01-01

    Full Text Available A series of novel polyurethane crosslinked structures (PUs was prepared from α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane-ethylene oxide (EO-PDMS-EO, 4,4’-methylenediphenyl diisocyanate and Boltorn® hyperbranched polyester of the third pseudo generation. The hydroxyfunctional hyperbranched aliphatic polyester with 26 end groups was used as crosslinking agent. In order to improve the compatibility of all reactants during the synthesis, PU samples were prepared by a step-growth polymerization in two stages in solution. The soft EO-PDMS-EO segment content was varied in the range from 15 to 40 wt.%. The influence of the EO-PDMS-EO content on the swelling behavior, crosslinking density, hardness, thermal and surface properties of the synthesized PUs was investigated. The structure of the synthesized polyurethanes was confirmed by the presence of specific bands in Fourier transform infrared spectra. Swelling studies were carried out to determine the crosslinking density and polyurethane networks with lower EOPDMS- EO content revealed higher crosslinking density. The glass transition temperature of the synthesized PUs, determined by differential scanning calorimetry, slightly increased from 50 to 58°C by decreasing EO-PDMS-EO content as a consequence of higher crosslinking density of samples. The increase of EO-PDMS-EO content leads to the better thermal stability, as it was confirmed by the value of the starting temperature of thermal degradation. The surface of the polyurethane networks became more hydrophobic with increasing EO-PDMS-EO content. The surface morphology of synthesized polyurethanes was analyzed by scanning electron microscopy.

  16. Controlled Synthesis of Uniform Cobalt Phosphide Hyperbranched Nanocrystals Using Tri- n -octylphosphine Oxide as a Phosphorus Source

    KAUST Repository

    Zhang, Haitao

    2011-01-12

    A new method to produce hyperbranched Co 2P nanocrystals that are uniform in size, shape, and symmetry was developed. In this reaction tri-n-octylphosphine oxide (TOPO) was used as both a solvent and a phosphorus source. The reaction exhibits a novel monomer-saturation-dependent tunability between Co metal nanoparticle (NP) and Co 2P NP products. The morphology of Co 2P can be controlled from sheaflike structures to hexagonal symmetric structures by varying the concentration of the surfactant. This unique product differs significantly from other reported hyperbranched nanocrystals in that the highly anisotropic shapes can be stabilized as the majority shape (>84%). This is the first known use of TOPO as a reagent as well as a coordinating background solvent in NP synthesis. © 2011 American Chemical Society.

  17. Influence of nanoclay particles modification by polyester-amide hyperbranched polymer on the corrosion protective performance of the epoxy nanocomposite

    International Nuclear Information System (INIS)

    Highlights: • Nanoclay particles were modified with polyester-amide hyperbranched polymer. • Epoxy/clay nanocomposites were prepared using modified clay particles. • Surface modification enhanced the clay particles exfoliation properties. • Surface modified clay particles enhanced corrosion resistance of the epoxy coating. - Abstract: Surface modification of nanoclay particles was carried out by various amounts of polyester-amide hyperbranched polymer (HBP). Thermal gravimetric analysis and X-ray diffraction analysis were performed to estimate the efficiency of the HPB grafting on the clay particles. Epoxy/clay nanocomposites were prepared by addition of 1 wt.% unmodified and modified clays. The corrosion protection properties of the nanocomposites were evaluated by electrochemical impedance spectroscopy (EIS). Results revealed that surface modification of the clay particles by HBP caused significant enhancement of the epoxy coating corrosion resistance especially when the ‘polymer/clay’ ratios were 10/1 and 5/1

  18. Comparison of Properties among Dendritic and Hyperbranched Poly(ether ether ketones and Linear Poly(ether ketones

    Directory of Open Access Journals (Sweden)

    Atsushi Morikawa

    2016-02-01

    Full Text Available Poly(ether ether ketone dendrimers and hyperbranched polymers were prepared from 3,5-dimethoxy-4′-(4-fluorobenzoyldiphenyl ether and 3,5-dihydroxy-4′-(4-fluorobenzoyldiphenyl ether through aromatic nucleophilic substitution reactions. 1-(tert-Butyldimethylsiloxy-3,5-bis(4-fluorobenzoylbenzene was polycondensed with bisphenols, followed by cleavage of the protective group to form linear poly(ether ketones having the same hydroxyl groups in the side chains as the chain ends of the dendrimer and hyperbranched polymers. Their properties, such as solubilities, reduced viscosities, and thermal properties, were compared with one another. Similar comparisons were also carried out among the corresponding methoxy group polymers, and the size of the molecules was shown to affect the properties.

  19. Influence of end groups in hyperbranched polyesters used as modifiers in the characteristics of epoxy thermosets cured by adipic dihydrazide

    OpenAIRE

    Serra, A; A. M. Tomuta; X. Ramis; S. De la Flor

    2013-01-01

    Mixtures of diglycidylether of bisphenol A (DGEBA) resin and different ratios of aliphatic-aromatic hyperbranched polyester (HBP) were cured by a latent curing agent, adipic dihydrazide (AH). The HBPs prepared have hydroxyl groups or 10-undecenoyl or allyl groups as chain ends. The curing mixtures were investigated by differential scanning calorimetry (DSC) to study the curing process and to evaluate the kinetic parameters of the different formulations. These studies suggest that HBPs decreas...

  20. A New Epoxy-Based Layered Silicate Nanocomposite Using a Hyperbranched Polymer: Study of the Curing Reaction and Nanostructure Development

    OpenAIRE

    Pilar Cortés; Iria Fraga; Yolanda Calventus; Frida Román; John M. Hutchinson; Francesc Ferrando

    2014-01-01

    Polymer layered silicate (PLS) nanocomposites have been prepared with diglycidyl ether of bisphenol-A (DGEBA) epoxy resin as the matrix and organically modified montmorillonite (MMT) as the clay nanofiller. Resin-clay mixtures with different clay contents (zero, two, five and 10 wt%) were cured, both isothermally and non-isothermally, using a poly(ethyleneimine) hyperbranched polymer (HBP), the cure kinetics being monitored by differential scanning calorimetry (DSC). The nanostructure of the ...

  1. Study on the morphology and thermomechanical properties of poly(urethane-siloxane) networks based on hyperbranched polyester

    OpenAIRE

    Pergal Marija V.; Džunuzović Jasna V.; Špírková Milena; Poręba Rafal; Steinhart Miloš; Pergal Miodrag M.; Ostojić Sanja

    2013-01-01

    Two series of polyurethane films based on hyperbranched polyester of the second pseudogeneration (Boltorn®), 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO) and α,ω-dihydroxypropyl-poly(dimethylsiloxane) (HP-PDMS), were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomec...

  2. Highly efficient hybrid photovoltaics based on hyperbranched three-dimensional TiO2 electron transporting materials

    KAUST Repository

    Mahmood, Khalid

    2015-03-23

    A 3D hyperbranched TiO2 electron transporting material is demonstrated, which exhibits superior carrier transport and lifetime, as well as excellent infiltration, leading to highly efficient mesostructured hybrid solar cells, such as lead-halide perovskites (15.5%) and dye-sensitized solar cells (11.2%). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Stimuli-Responsive Biodegradable Hyperbranched Polymer-Gadolinium Conjugates as Efficient and Biocompatible Nanoscale Magnetic Resonance Imaging Contrast Agents.

    Science.gov (United States)

    Sun, Ling; Li, Xue; Wei, Xiaoli; Luo, Qiang; Guan, Pujun; Wu, Min; Zhu, Hongyan; Luo, Kui; Gong, Qiyong

    2016-04-27

    The efficacy and biocompatibility of nanoscale magnetic resonance imaging (MRI) contrast agents depend on optimal molecular structures and compositions. Gadolinium [Gd(III)] based dendritic macromolecules with well-defined and tunable nanoscale sizes are excellent candidates as multivalent MRI contrast agents. Here, we propose a novel alternate preparation of biodegradable hyperbranched polymer-gadolinium conjugates via a simple strategy and report potentially efficient and biocompatible nanoscale MRI contrast agents for cancer diagnosis. The enzyme-responsive hyperbranched poly(oligo-(ethylene glycol) methacrylate)-gadolinium conjugate (HB-POEGMA-Gd) was prepared via one-step reversible addition-fragmentation chain transfer (RAFT) polymerization and Gd(III) chelating, and the cRGDyK functionalized polymer (HB-POEGMA-cRGD-Gd) was obtained via click chemistry. By using an enzyme similar to lysosomal cathepsin B, hyperbranched conjugates of high molecular weights (MW) (180 and 210 kDa) and nanoscale sizes (38 and 42 nm) were degraded into low MW (25 and 30 kDa) and smaller products (4.8 and 5.2 nm) below the renal threshold. Conjugate-based nanoscale systems had three-fold more T1 relaxivity compared to clinical agent diethylenediaminepentaacetic acid (DTPA)-Gd. Animal studies with the nanoscale system offered greater tumor accumulation and enhanced signal intensity (SI) in mouse U87 tumors of which the greatest activity was conferred by the cRGDyK moiety functionalized hyperbranched conjugate. In vitro cytotoxicity, hemocompatibility and in vivo toxicity studies confirmed no adverse events. This design strategy for multifunctional Gd(III)-labeled biodegradable dendritic macromolecules may have significant potential as future efficient, biocompatible polymeric nanoscale MRI diagnostic contrast agents for cancer.

  4. Effect of Hyperbranched Poly(amine-ester) Grafted Nano-SiO2 on Reinforcement and Toughness of PVC

    Institute of Scientific and Technical Information of China (English)

    LI Jie; ZHAO Hui; SUN Rui-min; LUO Yun-jun

    2008-01-01

    Nano-SiO2 was modified using silane coupling agent (KH-550) and hyperbranched poly(amine-ester) respectively, and Poly(vinyl chloride) (PVC)/modified nano-SiO2 composites were made by melt-blending. The composites' structures andmechanical properties were characterized by transmission electron microscopy(TEM), sanning electronic microscopy(SEM) and electronic universal testing machine. The results show that nano-SiO2 grafted by hyperbranched poly (amine-ester) increases obviously in dispersion in PVC matrix, and mechanical properties of PVC are effectively improved. Moreover, it was found that mechanical properties of PVC/nano-SiO2 composites reach the best when weight percent of nano-SiO2 in PVC matrix is 1%. Compared with crude PVC, the tensile strength of hyperbranched poly (amine-ester) grafted nano-SiO2/PVC composite increases by 24.68% and its break elongation, flexural strength and impact strength increase by 15.73%, 4.07% and 1841.84%, respectively. Moreover, the processing of the composites is improved.

  5. Tissue coverage of a hydrophilic polymer-coated zotarolimus-eluting stent vs. a fluoropolymer-coated everolimus-eluting stent at 13-month follow-up: an optical coherence tomography substudy from the RESOLUTE All Comers trial

    DEFF Research Database (Denmark)

    Gutiérrez-Chico, Juan Luis; van Geuns, Robert Jan; Regar, Evelyn;

    2011-01-01

    To compare the tissue coverage of a hydrophilic polymer-coated zotarolimus-eluting stent (ZES) vs. a fluoropolymer-coated everolimus-eluting stent (EES) at 13 months, using optical coherence tomography (OCT) in an 'all-comers' population of patients, in order to clarify the mechanism of eventual...

  6. 超支化聚合物在熔体静电纺丝中的应用%Application of Hyperbranched Polymer in Melt Electrospinning

    Institute of Scientific and Technical Information of China (English)

    夏令涛; 刘勇; 丁玉梅; 苑会林; 杨卫民

    2012-01-01

    Different molecular weights,different amounts of hyperbranched polyester modified polypropylene,the effect of hyperbranched polymer on polypropylene melt electrospun fiber diameter was studied. The results showed that hyperbranched polyester could significantly reduce the diameter of the polypropylene fiber, hyperbranched polymers of different molecular weight had a different impact on polypropylene fiber diameter, when adding eight hyperbranched polyester H203 ( relative to the mass of 100 copies of the polypropylene) ,the diameter of polypropylene fiber was 1-2 μm,and distributed uniformly.%采用不同分子量、不同含量的超支化聚酯对聚丙烯进行改性,研究超支化聚合物对聚丙烯熔体电纺纤维直径的影响.结果表明:超支化聚酯可以显著降低聚丙烯纤维直径,不同分子量的超支化聚合物对聚丙烯纤维直径影响有较大差异,当加入8份超支化聚酯H203(相对于质量为100份的聚丙烯)时,聚丙烯纤维直径可达到1~2μm,且分布均匀.

  7. 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

  8. 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

  9. 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

  10. 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 ...

  11. 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

  12. 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

  13. 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

  14. One-pot synthesis of hyperbranched poly(amido amine) clicked with a sugar shell via Michael addition polymerization and thiol click reaction

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper reports the production of glycopolymers via a simple and flexible method.A novel glycopolymer with a hyperbranched poly(amido amine) core and a sugar shell (HPAA-GLc) was synthesized by using thiol-ene click reaction via facile one-pot method.Hyperbranched poly(amido amine) with vinyl terminals was first synthesized by Michael addition polymerization of N,N’-methylene bisacrylamide (MBA) with 1-(2-aminoethyl) piperazine (AEPZ).Subsequently,thiol-ene click reaction between vinyl units of hyperbranched poly(amido amine) and thio-glucose was performed in situ.Based on the NMR result,all the vinyl groups reacted with thiol-glucose in 120 min.Strong photoluminescence emission was observed from the aqueous solution of HPAA-GLc.

  15. 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.

  16. 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.

  17. Bisphenol-A epoxy resin reinforced and toughened by hyperbranched epoxy resin

    Institute of Scientific and Technical Information of China (English)

    ZHANG Daohong; JIA Demin; HUANG Xianbo

    2007-01-01

    The study on toughening and reinforcing of bisphenol-A epoxy resin is one of important developmental direction in the field.This paper reports a one-pot synthesis of aromatic polyester hyperbranched epoxy resin HTDE-2,an effect of HTDE-2 content on the mechanical and thermal performance of the bisphenol-A (E51)/HTDE-2 hybrid resin in detail.Fourier transform infrared (FT-IR) spectrometer,scanning electronic microscopy (SEM),differential scanning calorimetry (DSC),thermogravimetric analysis (TGA),dynamic mechanical thermal analysis (DMA) and molecular simulation technology are used to study the structure of HTDE-2,performance and toughening and reinforcing mechanism of the HTDE-2/E51 hybrid resin.It has been shown that the content of HTDE-2 has an important effect on the performance of the hybrid resin,and the performance of the HTDE-2/E51 blends has maximum with the increase in HTDE-2 content.The impact strength and fracture toughness of the hybrid resin with 9 wt-% HTDE-2 are almost 3.088 and 1.749 times of E51 performance respectively,furthermore,the tensile and flexural strength can also be enhanced about 20.7% and 14.2%,respectively.The glass transition temperature and thermal degradation temperature,however,are found to decrease to some extent.

  18. Composite Electrolyte Membranes from Partially Fluorinated Polymer and Hyperbranched, Sulfonated Polysulfone

    Directory of Open Access Journals (Sweden)

    Surya Subianto

    2013-12-01

    Full Text Available Macromolecular modification of poly(vinylidene fluoride-co-hexafluoropropylene (PVDF was done with various proportions of sulfonic acid terminated, hyperbranched polysulfone (HPSU with a view to prepare ion conducting membranes. The PVDF-co-HFP was first chemically modified by dehydrofluorination and chlorosulfonation in order to make the membrane more hydrophilic as well as to introduce unsaturation, which would allow crosslinking of the PVDF-co-HFP matrix to improve the stability of the membrane. The modified samples were characterized for ion exchange capacity, morphology, and performance. The HPSU modified S-PVDF membrane shows good stability and ionic conductivity of 5.1 mS cm−1 at 80 °C and 100% RH for blends containing 20% HPSU, which is higher than the literature values for equivalent blend membranes using Nafion. SEM analysis of the blend membranes containing 15% or more HPSU shows the presence of spherical domains with a size range of 300–800 nm within the membranes, which are believed to be the HPSU-rich area.

  19. Multivalent anchored and crosslinked hyperbranched polyglycerol monolayers as antifouling coating for titanium oxide surfaces.

    Science.gov (United States)

    Wei, Qiang; Krysiak, Stefanie; Achazi, Katharina; Becherer, Tobias; Noeske, Paul-Ludwig Michael; Paulus, Florian; Liebe, Hendrik; Grunwald, Ingo; Dernedde, Jens; Hartwig, Andreas; Hugel, Thorsten; Haag, Rainer

    2014-10-01

    A set of new catecholic monolayer coatings was developed to improve the antifouling performance of TiO2 surfaces. To solve the problem of the weak charge-transfer interaction between a single catechol anchor and TiO2, multiple catechol groups were combined with hyperbranched polyglycerol (hPG) which is a distinct dendritic scaffold that exposes its multivalent anchor groups on the surface. Thus, multivalent catecholic hPGs can be easily prepared for surface modification. The immobilization of the compounds was monitored by quartz crystal microbalance with dissipation monitoring. Surface properties of the coatings were analyzed by water contact angle, X-ray photoelectron spectroscopy, and atomic force microscopy. The antifouling ability and stability were investigated by protein adsorption and cell adhesion. By increasing the number of catechol groups on the hPG scaffold, the stability and surface coverage could be significantly enhanced. Moreover, the inner-layer crosslinking of the coatings by grafting and initiating vinyl groups clearly improved their long-term stability. As a result, hPG with a catecholic functional degree of 10% (hPG-Cat10) and hPG with both catecholic and vinylic functional degree of 5% (hPG-Cat5-V5) were identified as the best catecholic hPGs to prepare bioinert and stable monolayer coatings on TiO2. PMID:25189471

  20. Isolation and characterization of a hyperbranched proteoglycan from Ganoderma lucidum for anti-diabetes.

    Science.gov (United States)

    Pan, Deng; Wang, Linqiang; Chen, Congheng; Hu, Bingwen; Zhou, Ping

    2015-03-01

    Presently, an efficient protein tyrosine phosphatase 1B (PTP1B) inhibitor, named FYGL-n, was isolated from Ganoderma Lucidum and characterized for its structure and bioactivity. Structure and chain conformation of FYGL-n based on both chemical and spectroscopic analysis showed that FYGL-n was a hyperbranched heteropolysaccharide bonded with protein via both serine and threonine residues by O-type glycoside, and showed a sphere observed by AFM. Specifically, monosaccharide composition indicated that FYGL-n consisted of D-arabinose, D-galactose, L-rhamnose and D-glucose in a mole ratio of 0.08:0.21:0.24:0.47, with a molecular mass of 72.9 kDa. The analysis of amino acids in FYGL-n indicated that there were 16 common amino acids, among which aspartic acid, glycine, serine, alanine, glutamic acid and threonine were the dominant components. Also it was demonstrated that FYGL-n could inhibit the PTP1B activity on a competitive mechanism in vitro.

  1. Temperature-Responsive Biocompatible Copolymers Incorporating Hyperbranched Polyglycerols for Adjustable Functionality

    Directory of Open Access Journals (Sweden)

    Alan J. House

    2011-08-01

    Full Text Available Temperature-triggered copolymers are proposed for a number of bio-applications but there is no ideal material platform, especially for injectable drug delivery. Options are needed for degradable biomaterials that not only respond to temperature but also easily accommodate linkage of active molecules. A first step toward realizing this goal is the design and synthesis of the novel materials reported herein. A multifunctional macromer, methacrylated hyperbranched polyglycerol (HPG-MA with an average of one acrylate unit per copolymer, was synthesized and copolymerized with N-isopropylacrylamide (NIPAAm, hydroxyethyl methacrylate-polylactide (HEMAPLA and acrylic acid (AAc. The potential to fully exploit the copolymers by modification of the multiple HPG hydroxyl groups will not be discussed here. Instead, this report focuses on the thermoresponsive, biocompatible, and degradation properties of the material. Poly(NIPAAm-co-HEMAPLA-co-AAc-co-HPG-MA displayed increasing lower critical solution temperatures (LCST as the HPG content increased over a range of macromer ratios. For the copolymer with the maximum HPG incorporation (17%, the LCST was ~30 °C. In addition, this sample showed no toxicity when human uterine fibroid cells were co-cultured with the copolymer for up to 72 h. This copolymer lost approximately 92% of its mass after 17 hours at 37 °C. Thus, the reported biomaterials offer attractive properties for the design of drug delivery systems where orthogonally triggered mechanisms of therapeutic release in relatively short time periods would be attractive.

  2. Molecular Mobility in Hyperbranched Polymers and Their Interaction with an Epoxy Matrix

    Directory of Open Access Journals (Sweden)

    Frida Román

    2016-03-01

    Full Text Available The molecular mobility related to the glass transition and secondary relaxations in a hyperbranched polyethyleneimine, HBPEI, and its relaxation behaviour when incorporated into an epoxy resin matrix are investigated by dielectric relaxation spectroscopy (DRS and dynamic mechanical analysis (DMA. Three systems are analysed: HBPEI, epoxy and an epoxy/HBPEI mixture, denoted ELP. The DRS behaviour is monitored in the ELP system in three stages: prior to curing, during curing, and in the fully cured system. In the stage prior to curing, DRS measurements show three dipolar relaxations: γ, β and α, for all systems (HBPEI, epoxy and ELP. The α-relaxation for the ELP system deviates significantly from that for HBPEI, but superposes on that for the epoxy resin. The fully cured thermoset displays both β- and α-relaxations. In DMA measurements, both α- and β-relaxations are observed in all systems and in both the uncured and fully cured systems, similar to the behaviour identified by DRS.

  3. Hyperbranched polyglycidol assisted green synthetic protocols for the preparation of multifunctional metal nanoparticles.

    Science.gov (United States)

    Li, Haiqing; Jo, Jung Kyu; Zhang, Li Dong; Ha, Chang-Sik; Suh, Hongsuk; Kim, Il

    2010-12-01

    Biocompatible hyperbranched polyglycidol (HBP) has been demonstrated to be an effective reducing and stabilizing agent for the synthesis of highly water-soluble monometallic (Au, Ag, Pt, Pd, and Ru) and bimetallic (Au/Pt, Au/Pd, and Au/Ru) nanoparticles (NPs), which provides a general and green protocol to fabricate metal NPs. The HBP-assisted reduction of metal ions follows an analogous polyol process. The reduction reaction rate increases sharply by increasing the temperature and the molecular weight of HBP. The size of NPs is controllable simply by changing the concentration of the metal precursor. High molecular weight HBP is favorable for the formation of NPs with uniform size and improved stability. By utilizing hydroxyl groups in the HBP-passivation layer of Au NPs, TiO(2)/Au, GeO(2)/Au, and SiO(2)/Au nanohybrids are also fabricated via sol-gel processes, which sets a typical example for the creation of versatile metal NPs/inorganic oxide hybrids based on the as-prepared multifunctional NPs. PMID:21047097

  4. Solid, double-metal cyanide catalysts for synthesis of hyperbranched polyesters and aliphatic polycarbonates

    Indian Academy of Sciences (India)

    Joby Sebastian; Srinivas Darbha

    2014-03-01

    Fe-Zn and Co-Zn double-metal cyanide (DMC) complexes exhibit highly efficient and selective catalytic activity for synthesis of hyperbranched polyesters (glycerol-succinic acid (G-SA) and glycerol-adipic acid (G-AA)) and aliphatic polycarbonates (via., alternative co-polymerization of cyclohexene oxide and CO2), respectively. The influence of method of preparation of DMC, in particular the mode of addition of reagents, on its physicochemical and catalytic properties was investigated. Co-Zn DMC was found highly selective for polycarbonate (than polyethers) formation. Catalysts prepared using tert-butanol and PEG-4000 as complexing and co-complexing agents, respectively, were found superior to those prepared without these agents. Apart from its role as a coordinating ligand, tert-butanol activated the Lewis acidic Zn2+ sites for reactions in polyester and polycarbonate formation. Hydrophobicity, micro-mesoporosity, acid strength and the amount of coordinated complexing agent are some of the crucial factors influenced the catalytic activity of DMC complexes.

  5. Non-isothermal crystallization kinetics of polypropylene and hyperbranched polyester blends☆

    Institute of Scientific and Technical Information of China (English)

    Qingchun Fan; Feihong Duan; Huaibing Guo; Tian Wu

    2015-01-01

    Polypropylene (PP) with different contents of the second generation hyperbranched polyester (HBP) is prepared by melt blending method. The non-isothermal crystallization kinetics of PP and PP/HBP blends is investigated under differential scanning calorimetry (DSC). The Mo equation is used to analyze the DSC data. The results show that the Mo theory is suitable for crystal ization kinetics of the blends. Fast cooling rate is not good for crys-tallizing and nucleating. The values of half crystal ization time (t1/2), crystal ization enthalpy (ΔHc) and temper-ature range (ΔT) of PP/HBP blends decrease when HBP is added. The required cooling rate of PP is higher than that of PP/HBP blends in order to reach the same relative crystal inity. Crystallization rate increases with the ad-dition of HBP. The crystallization rate reaches a maximum when the content of HBP is 5%. In addition, the activa-tion energies of PP and PP/HBP blends are calculated by Kissinger equation, revealing that the content of HBP has a little effect on the crystallization activation energy.

  6. 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

  7. 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

  8. 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.

  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. Peroxidase-like activity of gold nanoparticles stabilized by hyperbranched polyglycidol derivatives over a wide pH range

    Science.gov (United States)

    Drozd, Marcin; Pietrzak, Mariusz; Parzuchowski, Paweł; Mazurkiewicz-Pawlicka, Marta; Malinowska, Elżbieta

    2015-12-01

    The aim of this work was to carry out comparative studies on the peroxidase-like activity of gold nanoparticles (AuNPs) stabilized with low molecular weight hyperbranched polyglycidol (HBPG-OH) and its derivative modified with maleic acid residues (HBPG-COOH). The influence of the stabilizer to gold precursor ratio on the size and morphology of nanoparticles obtained was checked, and prepared nanoparticles were characterized by means of transmission electron microscopy and UV-Vis spectroscopy. The results indicated the divergent effect of increasing the concentration of stabilizers (HBPG-OH or HBPG-COOH) on the size of the nanostructures obtained. The gold nanoparticles obtained were characterized as having intrinsic peroxidase-like activity and the mechanism of catalysis in acidic and alkaline mediums was consistent with the standard Michaelis-Menten kinetics, revealing a strong affinity of AuNPs with 2, 2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 3, 3‧, 5, 5‧-tetramethylbenzidine (TMB), and significantly lower affinity towards phenol. By comparing the kinetic parameters, a negligible effect of polymeric ligand charge on activity against various types of substrates (anionic or cationic) was indicated. The superiority of steric stabilization via the application of tested low-weight hyperbranched polymers over typical stabilizers in preventing salt-induced aggregation and maintaining high catalytic activity in time was proved. The applied hyperbranched stabilizers provide a good tool for manufacturing gold-based nanozymes, which are highly stable and active over a wide pH range.

  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. 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

  1. 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.

  2. 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.

  3. 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.

  4. Tuning the thermoresponsive properties of Hyperbranched Poly(ester amide)s based on diisopropanolamine and cyclic dicarboxylic anhydrides

    OpenAIRE

    Kelland, Malcolm

    2011-01-01

    A range of water-soluble hyperbranched poly(ester amide)s has been synthesized with a view to studying their thermoresponsive behavior in water. Poly(ester amide)s with lower critical solution temperature (LCST) values around physiological temperatures are of interest for biological and medical applications, whereas poly(ester amide)s with high LCST values may be useful as kinetic hydrate inhibitors for high salinity produced fluids in the oil and gas industry. The LCST of these p...

  5. In situ preparation of fluorescent CdTe quantum dots with small thiols and hyperbranched polymers as co-stabilizers

    OpenAIRE

    Shi, Yunfeng; Ma, Zhimin; Cui, Ningning; Liu, Yanli; Hou, Xiaoyu; Du, Weimin; Liu, Lin; Gangsheng, Tong

    2014-01-01

    A new strategy for in situ preparation of highly fluorescent CdTe quantum dots (QDs) with 3-mercaptopropionic acid (MPA) and hyperbranched poly(amidoamine)s (HPAMAM) as co-stabilizers was proposed in this paper. MPA and HPAMAM were added in turn to coordinate Cd2+. After adding NaHTe and further microwave irradiation, fluorescent CdTe QDs stabilized by MPA and HPAMAM were obtained. Such a strategy avoids the aftertreatment of thiol-stabilized QDs in their bioapplication and provides an opport...

  6. Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide

    DEFF Research Database (Denmark)

    Liu, Shuiping; Gu, Tianxun; Fu, Jiajia;

    2014-01-01

    In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolates...... as NO donors, respectively. The nanospheres have spherical outline with dimension of ~ 127 nm. The data of systematic characterization demonstrated that the mHP-based hybrid nanosphere vehicles (QDs-mHP-NO) can release and real-time detect NO with the low limit of 25 nM, based on fluorescence quenching...

  7. Synthesis of Aromatic Hyperbranched Polyesters and Modification of Their End-groups%全芳型超支化聚酯的合成及端基改性

    Institute of Scientific and Technical Information of China (English)

    唐黎明

    2001-01-01

    Soluble aromatic hyperbranched polyesters with controlled viscosities have been preparedby melt polycondensation of sililated 5-acetoxyisophathalic acid with sililated p-tert-butyl benzoic acidin various molar ratios. By further reaction with thionyl chloride and propargyl alcohol successively,the endgroups of the crude polyester were transferred into ethynylic groups in 78. 2% yield as calculat-ed by 1H NMR spectra.

  8. Photovoltaics: Highly Efficient Hybrid Photovoltaics Based on Hyperbranched Three-Dimensional TiO 2 Electron Transporting Materials (Adv. Mater. 18/2015)

    KAUST Repository

    Mahmood, Khalid

    2015-05-01

    Solution-processed hybrid photovoltaics are a potentially disruptive third-generation solar cell technology. On page 2859, A. Amassian and co-workers demonstrate that an electrospun hyperbranched electron-transporting material is capable of achieving highly efficient hybrid solar cells across different platforms, including lead-halide perovskites (15.5%) and dye-sensitized solar cells (11.2%).

  9. 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

  10. Progesterone binding nano-carriers based on hydrophobically modified hyperbranched polyglycerols

    Science.gov (United States)

    Alizadeh Noghani, M.; Brooks, D. E.

    2016-02-01

    Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The results provide evidence to justify more detailed studies of interactions with biological systems, both single cells and in animal models.Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The

  11. Novel Low-Density Ablators Containing Hyperbranched Poly(azomethine)s

    Science.gov (United States)

    Tigelaar, Dean

    2011-01-01

    An ablative composite is low-density (0.25 to 0.40 g/cu cm), easy to fabricate, and superior to the current state-of-the-art ablator (phenolic impregnated carbon ablator, PICA) in terms of decomposition temperature, char yield, and mechanical strength. Initial ablative testing with a CO2 laser under high-heat-flux (1,100 W/sq cm) conditions showed these new ablators are over twice as effective as PICA in terms of weight loss, as well as transfer of heat through the specimen. The carbon fiber/poly(azomethine) composites have the same density as PICA, but are 8 to 11 times stronger to irreversible breaking by tensile compression. In addition, polyazomethine char yields by thermogravimetric analysis are 70 to 80 percent at 1,000 C. This char yield is 10 to 20 percent higher than phenolic resins, as well as one of the highest char yields known for any polymer. A high char yield holds the composite together better toward shearing forces on reentry, as well as reradiates high heat fluxes. This innovative composite is stronger than PICA, so multiple pieces can be sealed together without fracture. Researchers have also studied polyazomethines before as linear polymers. Due to poor solubility, these polymers precipitate from the polymerization solvent as a low-molecular-weight (2 to 4 repeat units) powder. The only way found to date to keep linear polyazomethines in solution is by adding solubilizing side groups. However, these groups sacrifice certain polymer properties. These hyperbranched polyazomethines are high molecular weight and fully aromatic.

  12. Antimicrobial hyperbranched poly(ester amide)/polyaniline nanofiber modified montmorillonite nanocomposites

    International Nuclear Information System (INIS)

    There has been growing interest in the use of nanomaterials featuring potent of antimicrobial activity in the biomedical domain. It still remains a challenge for the researchers to develop an efficient nanocomposite possessing antimicrobial efficacy against broad spectrum microbes including bacteria, fungi as well as algal consortium, posing serious challenges for the human survival. In addressing the above problem, we report the fabrication of bio-based hyperbranched poly(ester amide) (HBPEA)/polyaniline nanofiber modified montmorillonite (MMT) nanocomposites by an ex-situ polymerization technique at varied weight percentages (1, 2.5, 5 wt.%) of the modified MMT (nanohybrid). The Fourier transform infrared spectroscopy confirmed the structural changes upon interaction of the nanohybrid with HBPEA. A probable mechanism is proposed for the formation of nanocomposites with partially exfoliated nanoplatelet structure, which was further confirmed from the high resolution transmission electron microscopic analyses. The prepared nanocomposites exhibited potent efficacy against gram positive bacteria like Bacillus subtilis and Staphylococcus aureus as compared to the gram negative ones like Pseudomonas aeruginosa and Escherichia coli. The nanocomposites showed significant antifungal activity against Aspergillus niger, Fusarium oxysporum and Coleotricum capcii and antialgal activity against algal consortium comprising of Chlorella, Hormidium and Cladophorella species. The formation of thermosetting nanocomposites resulted in the acceptable improvement of desired physico-chemical and mechanical properties including thermostability. Thus pronounced antimicrobial activity of the nanocomposites against a spectrum of bacterial and fungal strains as well as a consortium of algal species along with other desired performance vouched them as potent antimicrobial materials in the realm of health and biomedical industry. - Highlights: • A possible approach for fabrication of the

  13. 188Re-LABELED HYPERBRANCHED POLYSULFONAMINE AS A ROBUST TOOL FOR TARGETED CANCER DIAGNOSIS AND RADIOIMMUNOTHERAPY

    Institute of Scientific and Technical Information of China (English)

    Nan Li; Yue Jin; Li-zhe Xue; Pei-yong Li; De-yue Yan; Xin-yuan Zhu

    2013-01-01

    Hyperbranched polysulfonamine (HPSA) is a promising biomaterial due to its highly branched spherical architecture and efficient intracellular translocation.To realize the functionalization of HPSA,both N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) for tethering the human-mouse chimeric monoclonal antibody CH12 and N-hydroxy succinimidyl S-acetylmercaptoacetyltriglycinate (NHS-MAG3) for labeling 188Re were sequentially grafted onto the primary amine terminals of HPSA via covalent linkages,attaining the SPDP-HPSA-MAG3 intermediate.In order to reserve the structural integrity of CH12,the fragment crystallizable (Fc) region was also processed by oxidation of oligosaccharide moieties with sodium periodate and then reacted with N-(κ-maleimidoundecanoic acid) hydrazide (KMUH).After chelating 188Re with MAG3 group,the SPDP was reduced to PDP and connected onto the maleinimide group at the Fc region.As a result,both the epidermal growth factor receptor vIII (EGFRvIII) targeted monoclonal antibody CH12 and the radionuclide 188Re were conjugated to the HPSA-based vehicles,forming the 188Re-labeled and CH12-tethered HPSA (CH12-HPSA-188Re).The molecular weight and in vitro stability of CH12-HPSA-l88Re were evaluated by gel electrophoresis and paper chromatography.On one hand,the CH12-HPSA-188Re could specifically bind to the EGFRvIII-positive human hepatocarcinoma cells in vitro.On the other hand,it could also target at the tumor tissue of nude mice in vivo.Hence,the CH12-HPSA-188Re could effectively target at the human hepatocarcinoma and facilitate the tumor detection and targeted radioimmunotherapy.

  14. Antimicrobial hyperbranched poly(ester amide)/polyaniline nanofiber modified montmorillonite nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Pramanik, Sujata [Advanced Polymer and Nanomaterial Laboratory, Department of Chemical Sciences, Tezpur University, Tezpur 784028 (India); Bharali, Pranjal; Konwar, B.K. [Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur 784028 (India); Karak, Niranjan, E-mail: karakniranjan@yahoo.com [Advanced Polymer and Nanomaterial Laboratory, Department of Chemical Sciences, Tezpur University, Tezpur 784028 (India)

    2014-02-01

    There has been growing interest in the use of nanomaterials featuring potent of antimicrobial activity in the biomedical domain. It still remains a challenge for the researchers to develop an efficient nanocomposite possessing antimicrobial efficacy against broad spectrum microbes including bacteria, fungi as well as algal consortium, posing serious challenges for the human survival. In addressing the above problem, we report the fabrication of bio-based hyperbranched poly(ester amide) (HBPEA)/polyaniline nanofiber modified montmorillonite (MMT) nanocomposites by an ex-situ polymerization technique at varied weight percentages (1, 2.5, 5 wt.%) of the modified MMT (nanohybrid). The Fourier transform infrared spectroscopy confirmed the structural changes upon interaction of the nanohybrid with HBPEA. A probable mechanism is proposed for the formation of nanocomposites with partially exfoliated nanoplatelet structure, which was further confirmed from the high resolution transmission electron microscopic analyses. The prepared nanocomposites exhibited potent efficacy against gram positive bacteria like Bacillus subtilis and Staphylococcus aureus as compared to the gram negative ones like Pseudomonas aeruginosa and Escherichia coli. The nanocomposites showed significant antifungal activity against Aspergillus niger, Fusarium oxysporum and Coleotricum capcii and antialgal activity against algal consortium comprising of Chlorella, Hormidium and Cladophorella species. The formation of thermosetting nanocomposites resulted in the acceptable improvement of desired physico-chemical and mechanical properties including thermostability. Thus pronounced antimicrobial activity of the nanocomposites against a spectrum of bacterial and fungal strains as well as a consortium of algal species along with other desired performance vouched them as potent antimicrobial materials in the realm of health and biomedical industry. - Highlights: • A possible approach for fabrication of the

  15. 超支化聚己内酯的制备与表征%Preparation and Characterization of Hyperbranched Polycaprolactone

    Institute of Scientific and Technical Information of China (English)

    刘啸天; 范洪波; 刘传生; 罗群

    2014-01-01

    This work is directed to developing a method for the synthesis and characterisation of hyperbranched polymers combining enzymatic Ring-opening Polymerization ( ROP) and self-condensing vinyl polymerization ( SCVP) .Macromer is pre-pared by Novozyme 435 catalyzed ROP of ε-CL, and subsequently converted to AB* macroinimer by the esterification with α-bromoisobutyryl bromide .The target of hyperbranched polycaprolactone is obtained by SCVP of AB * macroinimer via atom transfer radical polymerization ( ATRP) .%在Novozyme 435固定化脂肪酶催化下,甲基丙烯酸羟乙酯( HEMA)引发己内酯(ε-CL)开环聚合反应,得到分别以双键和羟基封端的直链聚己内酯( PCL )产物;利用α-溴代异丁酰溴与开环聚合产物的端羟基发生酯化反应,得到大分子型AB*单体;再以CuCl/bpy (联吡啶)为催化体系,令大分子型AB*单体通过自缩合乙烯基聚合反应(利用原子转移自由基聚合反应形式),成功合成了超支化聚己内酯目标产物。

  16. Synthesis and Characterization of the Hyperbranched Polyester%超支化聚酯的合成与表征

    Institute of Scientific and Technical Information of China (English)

    曹胜光; 翁家宝

    2001-01-01

    The one-step synthesis of a hyperbranched polyester based upon 3,5-dihydroxy benzoic acid and 3,5-dihydroxy toluene has succeeded in getting hybranched polyester. This kind of hyperbranched polymer has showed to exhibit the properties of low viscosity and high solubility.%以3,5二羟基甲苯和3,5二羟基苯甲酸为原料,采用“一锅煮”的方法合成了超支化聚酯.通过不同的原料配比来控制超支化的向外的链扩展,每个分子形成大约2,4,8个酯结构的超支化臂.该超支化聚合物具有一定刚性的二维结构,不会产生分子链的缠结,而且显示出低粘度、低熔点和良好的溶解性等特点.

  17. 4-Dimethylaminopyridine promoted interfacial polymerization between hyperbranched polyesteramide and trimesoyl chloride for preparing ultralow-pressure reverse osmosis composite membrane.

    Science.gov (United States)

    Qin, Jiaxu; Lin, Saisai; Song, Shuqin; Zhang, Lin; Chen, Huanlin

    2013-07-24

    We have presented a concept of ultralow-pressure reverse osmosis membrane based on hyperbranched polyesteramide through interfacial reaction promoted by pyridine derivate. In this strategy, a key catalyst of 4-dimethylaminopyridine, which can both eliminate the steric hindrance of acyl transfer reaction and facilitate the phase transfer in interfacial polymerization, is adopted to drive the formation of a thin film composite membrane from the hyperbranched polyesteramide and trimesoyl chloride. The results of the characterization demonstrate that a dense, rough, and hydrophilic active layer with a thickness of about 100 nm is formed when the 4-dimethylaminopyridine catalyst is used. The salt rejections for Na2SO4, NaCl, and MgSO4 of the as-prepared composite membrane are higher than 92%, especially for Na2SO4 with 98% rejection. The water fluxes reach about 30-40 L·m(-2)·h(-1) even at an operation pressure of 0.6 MPa. The membrane exhibits good chlorine-resistance ability but poor resistance abilities to acidic and alkaline solutions in the physical-chemical stability experiment. It is also found that the resultant membrane possesses excellent separation performance for PEG-200, showing a promising way to separate small organic molecules from water.

  18. 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.

  19. 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.

  20. 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 ...

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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...

  6. 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...

  7. 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

  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. Application of hyperbranched rolling circle amplification for direct detection of mycobacterium tuberculosis in clinical sputum specimens.

    Directory of Open Access Journals (Sweden)

    Yang Liu

    Full Text Available BACKGROUND: Global tuberculosis (TB control is encumbered by the lack of a rapid and simple detection method for diagnosis, especially in low-resource areas. An isothermal amplification method, hyperbranched rolling circle amplification (HRCA, was optimized to detect Mycobacterium tuberculosis (Mtb in clinical sputum specimens. METHODS: A clinical validation study was performed to assess the diagnostic accuracy of HRCA. In order to analyze the detection limit of HRCA under optimal conditions, the method was initially used to detect purified H37Rv strain DNA and culture suspensions. Next, three strains of Mycobacterium tuberculosis complex (MTC and eight strains of non-tuberculosis mycobacterium (NTM were analyzed in order to evaluate specificity. Sputum specimens from 136 patients with diagnosed pulmonary TB, 38 lung cancer patients, and 34 healthy donors were tested by HRCA to validate the clinical application of HRCA for the rapid detection of Mtb. RESULTS: The detection limit of HRCA for purified H37Rv DNA and culture suspensions was 740 aM and 200cfu/ml, respectively. The results of all MTC strains were positive in contrast to the NTM specimens which were all negative. The detection sensitivity for the 136 sputum specimens from TB patients was 77.2% (105/136, which was slightly lower than that of quantitative real-time PCR(79.4%, 108/136 and culture (80.9%,110/136. The sensitivity of all three methods was statistically higher than smear microscopy (44.9%, 61/136. The overall specificity of HRCA was 98.6% (71/72 which was similar to that of quantitative real-time PCR (qRT-PCR and smear/culture methods (100%, 72/72. CONCLUSIONS: Use of the HRCA assay for detection of Mtb within clinical sputum specimens was demonstrated to be highly sensitive and specific. Moreover, the performance of HRCA is simple and cost-effective compared with qRT-PCR and is less time consuming than culture. Therefore, HRCA is a promising TB diagnostic tool that can be

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Bio-based hyperbranched thermosetting polyurethane/triethanolamine functionalized multi-walled carbon nanotube nanocomposites as shape memory materials.

    Science.gov (United States)

    Kalita, Hemjyoti; Karak, Niranjan

    2014-07-01

    Here, bio-based shape memory polymers have generated immense interest in recent times. Here, Bio-based hyperbranched polyurethane/triethanolamine functionalized multi-walled carbon nanotube (TEA-f-MWCNT) nanocomposites were prepared by in-situ pre-polymerization technique. The Fourier transform infrared spectroscopy and the transmission electron microscopic studies showed the strong interfacial adhesion and the homogeneous distribution of TEA-f-MWCNT in the polyurethane matrix. The prepared epoxy cured thermosetting nanocomposites exhibited enhanced tensile strength (6.5-34.5 MPa), scratch hardness (3.0-7.5 kg) and thermal stability (241-288 degrees C). The nanocomposites showed excellent shape fixity and shape recovery. The shape recovery time decreases (24-10 s) with the increase of TEA-f-MWCNT content in the nanocomposites. Thus the studied nanocomposites have potential to be used as advanced shape memory materials. PMID:24758045

  17. Water- and organo-dispersible gold nanoparticles supported by using ammonium salts of hyperbranched polystyrene: preparation and catalysis.

    Science.gov (United States)

    Gao, Lei; Nishikata, Takashi; Kojima, Keisuke; Chikama, Katsumi; Nagashima, Hideo

    2013-12-01

    Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles.

  18. Synthesis of cationic hyperbranched multiarm copolymer and its application in self-reducing and stabilizing gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel hyperbranched multiarm copolymer of HBPO-star-PDEAEMA with a hydrophobic poly(3-ethyl-3-(hydroxymethyl) oxetane)(HBPO) core and many cationic poly(2-(N,N-diethylamino) ethyl methacrylate)(PDEAEMA) arms has been synthesized through an atom transfer radical polymerization(ATRP) method,and been applied to spontaneously reduce and stabilize gold nanoparticles(AuNPs) in water without other additional agents.The size of the nanoparticles could be effectively controlled at about 4 nm,and the nanoparticles are extremely stable in solution without aggregation even for one year.It was found that solution pH and the molar ratio of N/Au have certain effects on the size and stability of AuNPs.This work provides a simple method for the synthesis of uniform and highly stable AuNPs.

  19. Influence of end groups in hyperbranched polyesters used as modifiers in the characteristics of epoxy thermosets cured by adipic dihydrazide

    Directory of Open Access Journals (Sweden)

    A. Serra

    2013-07-01

    Full Text Available Mixtures of diglycidylether of bisphenol A (DGEBA resin and different ratios of aliphatic-aromatic hyperbranched polyester (HBP were cured by a latent curing agent, adipic dihydrazide (AH. The HBPs prepared have hydroxyl groups or 10-undecenoyl or allyl groups as chain ends. The curing mixtures were investigated by differential scanning calorimetry (DSC to study the curing process and to evaluate the kinetic parameters of the different formulations. These studies suggest that HBPs decrease the curing rate of epoxy/AH in the case of vinyl terminated HPB, whereas OH terminated HBP accelerates the first stages and delays the lasts. The thermosets obtained showed an improvement in microhardness and impact strength without any reduction of the Tg and thermal parameters. Microparticle phase separation was observed with the undecenoyl HBP derivatives or when a 10% of allyl HBP derivative was in the formulation.

  20. 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.

  1. 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...

  2. 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 ...

  3. 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

  4. Effect and origin of the structure of hyperbranched polysiloxane on the surface and integrated performances of grafted Kevlar fibers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongrui; Yuan, Li [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Liang, Guozheng, E-mail: lgzheng@suda.edu.cn [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); National Engineering Laboratory for Modern Silk, Suzhou 215123 (China); Gu, Aijuan, E-mail: ajgu@suda.edu.cn [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China)

    2014-11-30

    Highlights: • Four new hyperbranched polysiloxanes (HPSis) with various structures were prepared. • HPSis have different molecular weights and contents of active groups. • Four grafted Kevlar fibers (HPSi-g-KFs) were facilely prepared with different HPSis. • The structure and properties of HPSi-g-KF depend on the structure of HPSi. • The origin behind greatly improved integrated properties of HPSi-g-KF is discussed. - Abstract: Four hyperbranched polysiloxanes (HPSis) with different molecular weights and concentration ratios of double bonds to epoxy groups (1:6.5–1:0.7) were synthesized and characterized. Each HPSi was facilely grafted onto surfaces of Kevlar fibers (KFs) to develop novel modified fibers (HPSi-g-KFs). The structures and integrated properties of HPSi-g-KFs as well as the origin behind were systematically investigated. Results show that HPSi-g-KFs have much rougher surface morphologies, and their surface free energies are as high as about 1.7 times that of KFs, showing greatly improved wettability. Besides, HPSi-g-KFs have excellent UV resistance after 168 h UV irradiation, the retentions of tenacity, energy to break, modulus and break extension are as high as 92, 86, 95 and 96%, respectively, while those of KFs are 66–85%. In addition, compared with KFs, HPSi-g-KFs have higher tensile tenacity and energy to break with similar modulus and break extension, much better thermal stability and flame retardancy. The nature of HPSi has different influence on different property of fibers, the HPSi with smaller molecular weight and more epoxy groups is beneficial to prepare HPSi-g-KFs with better wettability, while that with larger molecular weight and more double bonds tends to prepare HPSi-g-KF with better flame retardancy and UV resistance.

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

    International Nuclear Information System (INIS)

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

  6. Thermal Analyses of Blends of Hyperbranched Linear Low-density Polyethylene (LLDPE) with High-density Polyethylene and LLDPE Prepared by Dissolving Method

    OpenAIRE

    Triinu POLTIMÄE; Elvira TARASOVA; Andres KRUMME; Jaan ROOTS; Anti VIIKNA

    2011-01-01

    Blends of high-density polyethylene (HDPE), moderate and hyper-branched LLDPEs (LLDPE and HbPE, respectively) have attained widespread commercial applications, though the understanding of the mechanical and melt-flow properties of such blends has been handicapped by the absence of a consensus concerning the degrees of mixing of the components. Moreover, usually the blends are obtained by melt blending, which may not ensure the initial homogeneity of the components. In our work the mixtures we...

  7. SYNTHESIS OF A HYPERBRANCHED POLY(AROYLARYLENE) CONTAINING TRIAZOLE AND FLUORENE FUNCTIONALITIES BY CLICK CHEMISTRY AND METAL-FREE, REGIOSELECTIVE POLYCYCLOTRIMERIZATION

    Institute of Scientific and Technical Information of China (English)

    An-jun Qin; Cathy,K. W. Jim; Jacky,W. Y. Lam; Jing-zhi Sun; Ben Zhong Tang

    2009-01-01

    A new bis(aroylacetylene) containing tfiazole and fluorene moieties is synthesized by click chemistry.Polycyclotrimerization of the monomer is catalyzed by piperidine in refluxed dioxane,furnishing a regioregular poly(aroylarylene) in a satisfactory yield.The hyperbranched structure of the polymer is characterized spectroscopically with satisfactory results.The polymer enjoys no metal detriment and is soluble in common organic solvents such as tetrahydrofuran (THF), chloroform, dichloromethane (DCM), and N,N-dimethylformamide (DMF).

  8. Synthesis and properties of fluorine-containing hyperbranched polyester%含氟超支化聚酯的合成及其性能研究

    Institute of Scientific and Technical Information of China (English)

    孙义明; 谢霞; 毕小云

    2013-01-01

    利用十三氟辛酸对超支化聚酯进行端基改性,得到了含氟超支化聚酯.采用傅里叶变换红外光谱仪、差示扫描量热分析仪等对聚合物进行了表征和分析.结果表明:十三氟酸成功接枝到超支化聚酯上,含氟超支化聚醋的玻璃化转变温度为-20.5℃,含氟超支化聚酯溶液在固含量高达70%时仍具有较低的黏度,该聚合物成膜性好,涂膜的附着力为1级,柔韧性为1mm,铅笔硬度2H,抗冲击强度4.9 J/cm2,与水的接触角为105°,具有良好的表面疏水性.%The fluoride-containing hyperbranched polyester was prepared by the terminal group modification of hyperbranched polyester with tridecafluorooctanoic acid. The polymer was characterized and analyzed by Fourier transform infrared spectrometry and differential scanning calorimetry. The results showed that tridecafluorooctanoic acid was successfully grafted on hyperbranched polyester; the fluoride-containing hyperbranched polyester had the glass transition temperature of -20.5 ℃ and the solution thereof exhibited low viscosity and good film forming ability as the solid content was up to 70% ; and the film had adhesion grade 1, flexibility 1 mm, pencil hardness 2 H, anti-impact strength 4.9 J/cm2, water contact angle 105° and favorable surface hydrophobicity.

  9. 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.

  10. [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

  11. 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

  12. 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)

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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...

  1. 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

  2. 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

  3. 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...

  4. 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.

  5. 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...

  6. 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

  7. Simultaneous determination of iron and nickel in fluoropolymers by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry.

    Science.gov (United States)

    Soares, Bruno M; Santos, Rafael F; Bolzan, Rodrigo C; Muller, Edson I; Primel, Ednei G; Duarte, Fabio A

    2016-11-01

    This paper reports the development of a method of simultaneous determination of iron and nickel in fluoropolymers by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) with direct solid sampling. In order to carry out simultaneous measurements, both the main resonance line of nickel (232.003nm) and the adjacent secondary line of iron (232.036nm) were monitored in the same spectral window. The proposed method was optimized with a perfluoroalkoxy (PFA) sample and was applied to the determination of iron and nickel in fluorinated ethylene propylene (FEP) and modified polytetrafluoroethylene (PTFE-TFM) samples. Pyrolysis and atomization temperatures, as well as the use of Pd and H2 (during pyrolysis) as chemical modifiers, were carefully investigated. Compromise temperatures for pyrolysis and atomization of both analytes were achieved at 800 and 2300°C, respectively, using only 0.5Lmin(-1) H2 as chemical modifier during pyrolysis. Calibration curves were performed with aqueous standards by using a single solution which contained both analytes. Limits of detection were 221 and 9.6ngg(-1) for iron and nickel, respectively. Analyte concentrations in all samples ranged from 3.53 to 12.4µgg(-1) for iron and from 37 to 78ngg(-1) for nickel, with relative standard deviation less than 19%. Accuracy was evaluated by comparing these results with those obtained by inductively coupled plasma mass spectrometry after sample digestion by microwave-induced combustion and no significant statistical difference was observed. PMID:27591638

  8. 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.

  9. 超支化水煤浆分散剂的合成与性能研究%Synthesis of hyperbranched dispersant from coal water slurry and its chemical properties

    Institute of Scientific and Technical Information of China (English)

    张光华; 韩文静; 强轶; 刘龙; 尚婷; 赵方

    2012-01-01

    In this article, we have introduced a new type of disper-sant we have gained from the high-concentrated coal water slurry (CWS). To be exact, we have synthesized lower-generation hyper-branched molecular skeletons from the methanol solvent out of raw materials of dehydroabietylamine, methyl acrylate, and ethylenedi-amine through the divergent analysis. The actual products we have developed can be stated as follows: firstly, we have synthesized 0.5 generation hyperbranched organic molecules via Michael addition reaction with dehydroabietylamine as the principal acrylate raw material . Secondly, we have synthesized the 1.0 generation hyperbranched organic molecules through amidation condensation reaction by taking 0.5 generation hyperbranched molecule and ethylenediamine as the o- riginal materials. And, finally, the lower generation hyperbranched molecular skeleton can further be found to result in 1.0 generation hyperbranched organic molecules. The new-type dispersant of rosin hyperbranched from the coal water slurry has been synthetically made by using skeleton as initiator by making it react with the chloroactic acid. And, after that, we have applied infrared spectroscope and hydrogen nuclear magnetic resonance spectroscope to characterization of the 0.5 generation and 1.0 generation organic molecules and rosin hyperbranched dispersants. Moreover, we have done the slurry performance test with Shenfu coal for their viscosity, Zeta potential and static stability of the slurry. The results of our investigation indicate that the rosin hyperbranched dispersant has ability in reducing the viscosity of the coal slurry for this purpose at lower dosages. When the slurry concentration is lowered to 67% , and the dosage of the rosin hyperbranched dispersant was 0.4% ( quantity fraction) of the slurry, its viscosity tends to be only at 980 mPa · s. This shows that the rosin hyperbranched dispersant helps to improve the behavior of coal water slurry, enhance the static

  10. Conjugation of cytochrome c with ferrocene-terminated hyperbranched polymer and its influence on protein structure, conformation and function

    Science.gov (United States)

    Xiao, Fengjuan; Yue, Lin; Li, Song; Li, Xinxin

    2016-06-01

    Interaction mechanism of a new hyperbranched polyurethane-based ferrocene (HPU-Fc) with cytochrome c (cyt c) and cyt c structure and conformation change induced by HPU-Fc were investigated using cyclic voltammogram(CV), differential pulse voltammetry (DPV), circular dichroism (CD), fluorescence, synchronous fluorescence and absorbance spectroscopy technique. The peroxidase activity of cyt c in the presence of HPU-Fc was also studied. The structure and conformation of protein are relatively stable at moderate concentration of HPU-Fc without obvious perturbation of the heme pocket and significant changes in protein secondary structure. Conjugation of cyt c with excessive HPU-Fc (over about 3 times of cyt c) slightly changed the α-helix structure in protein, disturbed the microenvironment around heme as well as away from the heme crevice, which caused the changes of the electrochemical behavior and the absorption spectra. Reasonable amount of HPU-Fc has no significant influence on the protein enzymatic activity, while excess HPU-Fc may cause a conformation not suitable for H2O2 activation and guaiacol oxidation. The interaction of HPU-Fc with cyt c and the conservation of protein function at suitable HPU-Fc amount make prepared complex promising for the synergistic anticancer therapy. CV curves of 10 μM HPU-Fc, 10 μM cyt c and HPU-Fc/cyt c complex (n HPU-Fc: n cyt c = 3.5:1) in 0.5 M KCl (versus SCE) at a sweep rate of 100 mV ṡ s- 1 (b). Interaction mechanism of a new hyperbranched polyurethane-based ferrocene (HPU-Fc) with cytochrome c (cyt c) and cyt c structure and conformation change induced by HPU-Fc were investigated. The structure and conformation of protein are relatively stable at moderate concentration of HPU-Fc. Conjugation of cyt c with excessive HPU-Fc (over about 3 times of cyt c) slightly changed the α-helix structure in protein, disturbed the microenvironment around heme as well as away from the heme crevice, which caused the changes of the

  11. Progress on Application of the Substitutes for PFOA in Fluoro-polymers Synthesis%PFOA替代物在含氟聚合物中的应用研究进展

    Institute of Scientific and Technical Information of China (English)

    王佩刚; 方敏; 关旸; 傅公维; 许远远

    2013-01-01

    This review introduced the substitutes for PFOA as follow: the policy background and status of the development on the substitutes for PFOA, the progress on application of the substitutes for PFOA in fluoropolymer at home and abroad, the advantages and disadvantages of the application performance in fluoropolymer of the different substitutes for PFOA, and the trends of applied research of the substitutes for PFOA in fluoro-polymers.%简要介绍了PFOA替代物开发的政策背景;综述了国内外PFOA替代物的开发现状及其在含氟聚合物中的应用研究进展;比较了不同PFOA替代物在含氟聚合物中应用性能的优缺点;指出了PFOA替代物在含氟聚合物中应用研究的发展趋势。

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. Synthesis, Characterization and Self-Assembly of Amphiphilic Aromatic Hyperbranched Polyesters%两亲性芳香族超支化聚酯的合成、表征及自组装研究

    Institute of Scientific and Technical Information of China (English)

    李天亮; 韩生; 蔺华林; 周永丰

    2015-01-01

    以1,2,4-苯三酸酐和聚乙二醇(聚乙二醇300、聚乙二醇400、聚乙二醇600)为反应单体,首次通过缩聚法合成了一系列两亲性芳香族超支化聚酯.通过FT-IR、1H NMR、GPC、DSC、TGA对超支化聚酯的结构和性能进行了表征,结果表明,利用缩聚法成功合成了两亲性超支化聚酯,并且两亲性超支化聚酯的热性能稳定.两亲性超支化聚酯在水中自组装成囊泡,可以用作微反应器和药物封装等.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuiping; Gu, Tianxun; Fu, Jiajia [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China); Li, Xiaoqiang, E-mail: leecaiwei@163.com [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China); Technical University of Denmark, DTU Food, Søltofts plads, B227, 2800 Kgs. Lyngby (Denmark); Chronakis, Ioannis S. [Technical University of Denmark, DTU Food, Søltofts plads, B227, 2800 Kgs. Lyngby (Denmark); Ge, Mingqiao [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China)

    2014-12-01

    In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolates as NO donors, respectively. The nanospheres have spherical outline with dimension of ∼ 127 nm. The data of systematic characterization demonstrated that the mHP-based hybrid nanosphere vehicles (QDs-mHP-NO) can release and real-time detect NO with the low limit of 25 nM, based on fluorescence quenching mechanism. The low cell-toxicity of QDs-mHP-NO nanospheres was verified by means of MTT assay on L929 cells viability. The QDs-mHP-NO nanospheres provide perspectives for designing a new class of biocompatible NO donating and imaging systems. - Highlights: • QDs-mHP-NO fluorescent probe was prepared. • The QDs-mHP-NO probe is capable of releasing NO. • The QDs-mHP-NO probe can quantitatively detecting the release of NO in real time. • The low cell-toxicity of QDs-mHP-NO nanospheres was verified.

  9. Cure Kinetics of DGEBA with Hyperbranched Poly(3-hydroxyphenyl) Phosphate as Curing Agent Studied by Non-isothermal DSC

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The cure kinetics of diglycidyl ether of bisphenol A(DGEBA) with hyperbranched poly(3-hydroxyphenyl) phosphate(HHPP) as the curing agent was investigated by means of non-isothermal differential scanning calorimetry(DSC) at various heating rates. The results were compared with the corresponding results by using 1,3-dihydroxybenzene(DHB) as a model compound. The results show that HHPP can enhance the cure reaction of DGEBA, resulting in the decrease of the peak temperature of the curing curve as well as the decrease of the activation energy because of the flexible -P-O- groups in the backbone of HHPP. However, both the activation energy of the cured polymer and the peak temperature of the curing curve are increased with DHB as a curing agent. The cure kinetics of the DGEBA/HHPP system was calculated by using the isoconversional method given by Málek. It was found that the two-parameter autocatalytic model(esták-Berggren equation) is the most adequate one to describe the cure kinetics of the studied system at various heating rates. The obtained non-isothermal DSC curves from the experimental data show the results being accordant with those theoretically calculated.

  10. Solution-Stable Colloidal Gold Nanoparticles via Surfactant-Free, Hyperbranched Polyglycerol-b-polystyrene Unimolecular Templates.

    Science.gov (United States)

    Iocozzia, James; Lin, Zhiqun

    2016-07-19

    Hyperbranched polyglycerol-block-polystyrene copolymers, denoted HPG-b-PS, are synthesized and employed as a new and effective unimolecular template for synthesizing colloidal gold (Au) nanoparticles. The coordination of noble metal precursors with polyether within the inner HPG core and subsequent in situ reduction enables the formation of well-dispersed and stable PS-capped Au nanoparticles. The inner HPG core is produced via ring opening multibranching polymerization (ROMBP) and subsequently converted into atom transfer radical polymerization (ATRP) macroinitiators for the controlled growth of polystyrene (PS) arms possessing low polydispersity (PDI < 1.31). An initial investigation into the templating parameters of HPG-b-PS was undertaken by producing templates with different arm numbers (98 and 117) and different PS chain lengths (i.e., molecular weight = 3500-13400 g/mol). It was found that the PS chain length and solvent conditions affect the quality of the resulting PS-capped colloidal Au nanoparticles. This work demonstrates, for the first time, a simple, lower-cost approach for templating nonpolar solvent-soluble PS-capped Au nanoparticles on the order of 10-30 nm in diameter.

  11. Solution-Stable Colloidal Gold Nanoparticles via Surfactant-Free, Hyperbranched Polyglycerol-b-polystyrene Unimolecular Templates.

    Science.gov (United States)

    Iocozzia, James; Lin, Zhiqun

    2016-07-19

    Hyperbranched polyglycerol-block-polystyrene copolymers, denoted HPG-b-PS, are synthesized and employed as a new and effective unimolecular template for synthesizing colloidal gold (Au) nanoparticles. The coordination of noble metal precursors with polyether within the inner HPG core and subsequent in situ reduction enables the formation of well-dispersed and stable PS-capped Au nanoparticles. The inner HPG core is produced via ring opening multibranching polymerization (ROMBP) and subsequently converted into atom transfer radical polymerization (ATRP) macroinitiators for the controlled growth of polystyrene (PS) arms possessing low polydispersity (PDI numbers (98 and 117) and different PS chain lengths (i.e., molecular weight = 3500-13400 g/mol). It was found that the PS chain length and solvent conditions affect the quality of the resulting PS-capped colloidal Au nanoparticles. This work demonstrates, for the first time, a simple, lower-cost approach for templating nonpolar solvent-soluble PS-capped Au nanoparticles on the order of 10-30 nm in diameter. PMID:27357478

  12. Preparation of complementary glycosylated hyperbranched polymer/poly(ethylene glycol) brushes and their selective interactions with hepatocytes.

    Science.gov (United States)

    Liang, Su; Yu, Shan; Gao, Changyou

    2016-09-01

    Selective cell adhesion and migration, which mimics the natural biological events in vivo, is very important for the right repair of damaged tissues. In this study, glycosylated hyperbranched polymers (LA-HPMA) were synthesized, and were grafted on glass slide through dopamine deposition with different densities adjusted by co-grafting of poly(ethylene glycol) (PEG). The LA-HPMA and PEG molecular brushes were characterized by X-ray photoelectron spectroscopy (XPS), quartz crystal microbalance with dissipation (QCM-d) and ellipsometry. The adhesion of human hepatoma (HepG2) cells was promoted on the surface of a higher LA-HPMA density, and the migration rate was accelerated from 6.4μm/h on PEG surface to 12.7μm/h on 75% LA-HPMA surface. By contrast, the density and spreading area of mouse embryonic fibroblast (NIH3T3) cells were not significantly influenced by the LA-HPMA density, and the migration rate did not change significantly on all types of surfaces either. Therefore, the specific interactions of carbohydrate-protein can be used to modulate cell behaviors in vitro, for example the selective adhesion and migration of HepG2 cells. PMID:27209383

  13. Fabrication of magnetic water-soluble hyperbranched polyol functionalized graphene oxide for high-efficiency water remediation.

    Science.gov (United States)

    Hu, Lihua; Li, Yan; Zhang, Xuefei; Wang, Yaoguang; Cui, Limei; Wei, Qin; Ma, Hongmin; Yan, Liangguo; Du, Bin

    2016-01-01

    Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG < 0, ΔH < 0, ΔS < 0) implied that the adsorption process of MB, MV and Pb(II) was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where π-π stacking interactions, H-bonding interaction and electrostatic attraction dominated the adsorption of MB/MV and chelation and electrostatic attraction dominated the adsorption of Pb(II). In addition, the excellent reproducibility endowed MWHPO-GO with the potential for application in water remediation. PMID:27354318

  14. Fabrication of magnetic water-soluble hyperbranched polyol functionalized graphene oxide for high-efficiency water remediation

    Science.gov (United States)

    Hu, Lihua; Li, Yan; Zhang, Xuefei; Wang, Yaoguang; Cui, Limei; Wei, Qin; Ma, Hongmin; Yan, Liangguo; Du, Bin

    2016-01-01

    Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG < 0, ΔH < 0, ΔS < 0) implied that the adsorption process of MB, MV and Pb(II) was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where π-π stacking interactions, H-bonding interaction and electrostatic attraction dominated the adsorption of MB/MV and chelation and electrostatic attraction dominated the adsorption of Pb(II). In addition, the excellent reproducibility endowed MWHPO-GO with the potential for application in water remediation. PMID:27354318

  15. A New Epoxy-Based Layered Silicate Nanocomposite Using a Hyperbranched Polymer: Study of the Curing Reaction and Nanostructure Development

    Directory of Open Access Journals (Sweden)

    Pilar Cortés

    2014-03-01

    Full Text Available Polymer layered silicate (PLS nanocomposites have been prepared with diglycidyl ether of bisphenol-A (DGEBA epoxy resin as the matrix and organically modified montmorillonite (MMT as the clay nanofiller. Resin-clay mixtures with different clay contents (zero, two, five and 10 wt% were cured, both isothermally and non-isothermally, using a poly(ethyleneimine hyperbranched polymer (HBP, the cure kinetics being monitored by differential scanning calorimetry (DSC. The nanostructure of the cured nanocomposites was characterized by small angle X-ray scattering (SAXS and transmission electron microscopy (TEM, and their mechanical properties were determined by dynamic mechanical analysis (DMA and impact testing. The results are compared with an earlier study of the structure and properties of the same DGEBA-MMT system cured with a polyoxypropylene diamine, Jeffamine. There are very few examples of the use of HBP as a curing agent in epoxy PLS nanocomposites; here, it is found to enhance significantly the degree of exfoliation of these nanocomposites compared with those cured with Jeffamine, with a corresponding enhancement in the impact energy for nanocomposites with the low clay content of 2 wt%. These changes are attributed to the different cure kinetics with the HBP, in which the intra-gallery homopolymerization reaction is accelerated, such that it occurs before the bulk cross-linking reaction.

  16. Surface-initiated hyperbranched polyglycerol as an ultralow-fouling coating on glass, silicon, and porous silicon substrates.

    Science.gov (United States)

    Moore, Eli; Delalat, Bahman; Vasani, Roshan; McPhee, Gordon; Thissen, Helmut; Voelcker, Nicolas H

    2014-09-10

    Anionic ring-opening polymerization of glycidol was initiated from activated glass, silicon, and porous silicon substrates to yield thin, ultralow-fouling hyperbranched polyglycerol (HPG) graft polymer coatings. Substrates were activated by deprotonation of surface-bound silanol functionalities. HPG polymerization was initiated upon the addition of freshly distilled glycidol to yield films in the nanometer thickness range. X-ray photoelectron spectroscopy, contact angle measurements, and ellipsometry were used to characterize the resulting coatings. The antifouling properties of HPG-coated surfaces were evaluated in terms of protein adsorption and the attachment of mammalian cells. The adsorption of bovine serum albumin and collagen type I was found to be reduced by as much as 97 and 91%, respectively, in comparison to untreated surfaces. Human glioblastoma and mouse fibroblast attachment was reduced by 99 and 98%, respectively. HPG-grafted substrates outperformed polyethylene glycol (PEG) grafted substrates of comparable thickness under the same incubation conditions. Our results demonstrate the effectiveness of antifouling HPG graft polymer coatings on a selected range of substrate materials and open the door for their use in biomedical applications. PMID:25137525

  17. Study on the morphology and thermomechanical properties of poly(urethane-siloxane networks based on hyperbranched polyester

    Directory of Open Access Journals (Sweden)

    Pergal Marija V.

    2013-01-01

    Full Text Available Two series of polyurethane films based on hyperbranched polyester of the second pseudogeneration (Boltorn®, 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane-ethylene oxide (EO-PDMS-EO and α,ω-dihydroxypropyl-poly(dimethylsiloxane (HP-PDMS, were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomechanical and surface properties of the synthesized polyurethanes was studied by atomic force microscopy (AFM, small-angle X-ray scattering (SAXS, scanning electron microscopy (SEM, dynamic mechanical thermal analysis (DMTA and water absorption measurements. It was found that these techniques confirmed existence of microphase separated morphology. Synthesized polyurethanes exhibited two glass transition temperatures and one second relaxation process. The results showed that polyurethanes based on HP-PDMS had higher surface roughness, better microphase separation and waterproof performances. Samples synthesized with lower PDMS content had less hydrophobic surface, but higher crosslinking density and better thermomechanical properties. (Projekat Ministarstva nauke Republike Srbije, br. 172062

  18. Photoresponsive layer-by-layer ultrathin films prepared from a hyperbranched azobenzene-containing polymeric diazonium salt

    International Nuclear Information System (INIS)

    In this work, a hyperbranched diazonium salt (HB-DAS), prepared through azo-coupling reaction of an AB2 monomer (N, N-bis[2-(4-aminobenzoyloxy)ethyl]aniline), was used to prepare self-assembled multilayers and ultrathin films. Multilayer films were fabricated by dipping substrates in HB-DAS and other polyelectrolyte solutions alternately in a layer-by-layer (LBL) manner. It was somewhat surprising to observe that HB-DAS forms multilayer films with either a polyanion (poly(styrenesulfonate sodium salt), PSS) or a polycation (poly(diallyldimethylammonium chloride), PDAC) through alternate deposition in the solutions. Ultrathin films were formed in a sequential growth manner by dipping the substrates in the HB-DAS solution, washing with deionized water and drying repeatedly. In all the processes, the absorbance and thickness of the thin films linearly increase as the number of the dipping cycle increases. HB-DAS/PSS multilayer possesses an obviously larger bilayer thickness and lower density compared with the other two counterparts. The drying step after each deposition is necessary for the HB-DAS ultrathin film growth through the repeated dip-coating of HB-DAS. The multilayer and ultrathin films prepared by the above methods all show high resistance to erosion by organic solvents. The multilayers and ultrathin films exhibit photoinduced dichroism upon the irradiation of a polarized Ar+ laser beam

  19. Investigation on the interactions between fullerene and β-CD-g-hyperbranched polyglycerol to produce water-soluble fullerene

    Science.gov (United States)

    Eskandari, Mohammad; Najdian, Atena; Soleyman, Rouhollah

    2016-06-01

    Developing a successful way to solubilize C60 in water is a longstanding, critical, and challenging issue in nanotechnology, biological, and medicine applications because of the great potential of fullerene derivatives in anti-viral therapy. In the current study, an efficient strategy for the preparing of water-soluble C60 at room temperature has been developed by complexion of C60 with hyperbranched polyglycerol linked to the β-cyclodextrin core (β-CD-g-HPG). The interactions between C60 and β-CD-g-HPG were investigated using a range of analytical techniques such as FTIR, NMR, UV-vis spectroscopy as well as visual techniques including SEM and AFM images. The particle size for a 1:2 (C60: β-CD-g-HPG) complex was also determined to be monodisperse ∼60 nm from DLS, and it was appropriately matched with the size obtained from SEM pictures. The results show our synthesized hybrid nanomaterials will hopefully find interesting applications in biomedicine.

  20. Facile synthesis of titania/hyperbranched polyglycidol nanohybrids with controllable morphologies: from solid spheres, capsules to tubes

    Energy Technology Data Exchange (ETDEWEB)

    Li Haiqing; Zhang Lin; Jo, Jung Kyu; Ha, Chang-Sik; Shchipunov, Yury A.; Kim, Il, E-mail: ilkim@pusan.ac.kr [Pusan National University, WCU Center for Synthetic Polymer Bioconjugate Hybrid Materials, Department of Polymer Science and Engineering (Korea, Republic of)

    2011-05-15

    Titania/Hyperbranched polyglycidol (HBP) nanohybrids with tunable morphologies have been synthesized via a sol-gel process at ambient temperature. One-shot addition of varied amounts of titanium precursor tetraisopropoxide (TTIP) yields spherical titania/HBP solid particles with tunable size, while a controlled addition of TTIP results in spherical titania/HBP capsules. The average outer and inner diameters of the resultant capsules are also controllable according to the amount of TTIP via an Oswald ripening process. In addition, the modality of additional water supplied in the reaction systems can tune the morphologies of the resulting titania/HBP particles from nanocapsules to nanotubes owing to the accelerated hydrolysis rate of TTIP. The tunability in morphologies of the titania/HBP nanostructures ranging from solid spheres, capsules to tubes could be attributed to the self-assembly of a large amount of titania/HBP aggregates in a rapid, controlled and anisotropic manner, respectively. Surprisingly, by means of HBP contained in the resulting titania/HBP nanostructures, the gold nanoparticles are in situ generated and encapsulated into titania/HBP matrix in the absence of additional reducing agent. The as-prepared gold nanoparticles functionalized titania/HBP hybrids exhibit excellent catalytic function toward the reduction of 4-nitrophenol. This strategy demonstrates a typical example for functionalizing the titania/HBP hybrids targeted to specific applications.

  1. Effect and origin of the structure of hyperbranched polysiloxane on the surface and integrated performances of grafted Kevlar fibers

    Science.gov (United States)

    Zhang, Hongrui; Yuan, Li; Liang, Guozheng; Gu, Aijuan

    2014-11-01

    Four hyperbranched polysiloxanes (HPSis) with different molecular weights and concentration ratios of double bonds to epoxy groups (1:6.5-1:0.7) were synthesized and characterized. Each HPSi was facilely grafted onto surfaces of Kevlar fibers (KFs) to develop novel modified fibers (HPSi-g-KFs). The structures and integrated properties of HPSi-g-KFs as well as the origin behind were systematically investigated. Results show that HPSi-g-KFs have much rougher surface morphologies, and their surface free energies are as high as about 1.7 times that of KFs, showing greatly improved wettability. Besides, HPSi-g-KFs have excellent UV resistance after 168 h UV irradiation, the retentions of tenacity, energy to break, modulus and break extension are as high as 92, 86, 95 and 96%, respectively, while those of KFs are 66-85%. In addition, compared with KFs, HPSi-g-KFs have higher tensile tenacity and energy to break with similar modulus and break extension, much better thermal stability and flame retardancy. The nature of HPSi has different influence on different property of fibers, the HPSi with smaller molecular weight and more epoxy groups is beneficial to prepare HPSi-g-KFs with better wettability, while that with larger molecular weight and more double bonds tends to prepare HPSi-g-KF with better flame retardancy and UV resistance.

  2. Fabrication of magnetic water-soluble hyperbranched polyol functionalized graphene oxide for high-efficiency water remediation

    Science.gov (United States)

    Hu, Lihua; Li, Yan; Zhang, Xuefei; Wang, Yaoguang; Cui, Limei; Wei, Qin; Ma, Hongmin; Yan, Liangguo; Du, Bin

    2016-06-01

    Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG < 0, ΔH < 0, ΔS < 0) implied that the adsorption process of MB, MV and Pb(II) was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where π-π stacking interactions, H-bonding interaction and electrostatic attraction dominated the adsorption of MB/MV and chelation and electrostatic attraction dominated the adsorption of Pb(II). In addition, the excellent reproducibility endowed MWHPO-GO with the potential for application in water remediation.

  3. pH-Mediated Fluorescent Polymer Particles and Gel from Hyperbranched Polyethylenimine and the Mechanism of Intrinsic Fluorescence.

    Science.gov (United States)

    Liu, Shi Gang; Li, Na; Ling, Yu; Kang, Bei Hua; Geng, Shuo; Li, Nian Bing; Luo, Hong Qun

    2016-02-23

    We report that fluorescence properties and morphology of hyperbranched polyethylenimine (hPEI) cross-linked with formaldehyde are highly dependent on the pH values of the cross-linking reaction. Under acidic and neutral conditions, water-soluble fluorescent copolymer particles (CPs) were produced. However, under basic conditions, white gels with weak fluorescence emission would be obtained. The water-soluble hPEI-formaldehyde (hPEI-F) CPs show strong intrinsic fluorescence without the conjugation to any classical fluorescent agents. By the combination of spectroscopy and microscopy techniques, the mechanism of fluorescence emission was discussed. We propose that the intrinsic fluorescence originates from the formation of a Schiff base in the cross-linking process between hPEI and formaldehyde. Schiff base bonds are the fluorescence-emitting moieties, and the compact structure of hPEI-F CPs plays an important role in their strong fluorescence emission. The exploration on fluorescence mechanism may provide a new strategy to prepare fluorescent polymer particles. In addition, the investigation shows that the hPEI-F CPs hold potential as a fluorescent probe for the detection of copper ions in aqueous media. PMID:26829461

  4. Facile synthesis of titania/hyperbranched polyglycidol nanohybrids with controllable morphologies: from solid spheres, capsules to tubes

    International Nuclear Information System (INIS)

    Titania/Hyperbranched polyglycidol (HBP) nanohybrids with tunable morphologies have been synthesized via a sol–gel process at ambient temperature. One-shot addition of varied amounts of titanium precursor tetraisopropoxide (TTIP) yields spherical titania/HBP solid particles with tunable size, while a controlled addition of TTIP results in spherical titania/HBP capsules. The average outer and inner diameters of the resultant capsules are also controllable according to the amount of TTIP via an Oswald ripening process. In addition, the modality of additional water supplied in the reaction systems can tune the morphologies of the resulting titania/HBP particles from nanocapsules to nanotubes owing to the accelerated hydrolysis rate of TTIP. The tunability in morphologies of the titania/HBP nanostructures ranging from solid spheres, capsules to tubes could be attributed to the self-assembly of a large amount of titania/HBP aggregates in a rapid, controlled and anisotropic manner, respectively. Surprisingly, by means of HBP contained in the resulting titania/HBP nanostructures, the gold nanoparticles are in situ generated and encapsulated into titania/HBP matrix in the absence of additional reducing agent. The as-prepared gold nanoparticles functionalized titania/HBP hybrids exhibit excellent catalytic function toward the reduction of 4-nitrophenol. This strategy demonstrates a typical example for functionalizing the titania/HBP hybrids targeted to specific applications.

  5. Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide

    International Nuclear Information System (INIS)

    In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolates as NO donors, respectively. The nanospheres have spherical outline with dimension of ∼ 127 nm. The data of systematic characterization demonstrated that the mHP-based hybrid nanosphere vehicles (QDs-mHP-NO) can release and real-time detect NO with the low limit of 25 nM, based on fluorescence quenching mechanism. The low cell-toxicity of QDs-mHP-NO nanospheres was verified by means of MTT assay on L929 cells viability. The QDs-mHP-NO nanospheres provide perspectives for designing a new class of biocompatible NO donating and imaging systems. - Highlights: • QDs-mHP-NO fluorescent probe was prepared. • The QDs-mHP-NO probe is capable of releasing NO. • The QDs-mHP-NO probe can quantitatively detecting the release of NO in real time. • The low cell-toxicity of QDs-mHP-NO nanospheres was verified

  6. Sirtuin 1 evaluation with a novel immunoassay approach based on TiO2-Au label and hyperbranched polymer hybrid.

    Science.gov (United States)

    An, Yarui

    2016-08-15

    Accurate and highly sensitive evaluation of the sirtuin 1 (SirT1) level is becoming increasingly important for understanding the contribution of SirT1 in metabolism pathways. Here, a novel electrochemical immunoassay of SirT1 based on crosslinked hyperbranched azo-polymer decorated with gold colloids (Au-HAP) as sensing platform and titanium dioxide (TiO2)-Au nanocomposites to immobilize secondary antibody-horseradish peroxidase (Ab2-HRP) as electrochemical labels has been designed. Greatly enhanced sensitivity was achieved by exploiting the excellent conductivity of Au nanoparticle, the amplification effect of Au-HAP and TiO2-Au, and the favorable catalytic ability of HRP. The nanocomposites of Au-HAP and TiO2-Au could attach numerous capture antibodies on the surface for significant immune recognition efficiency. Meanwhile, the TiO2-Au-labeled Ab2-HRP using an HRP-thionine-H2O2 (hydrogen peroxide) detection system could further induce signal readout. Under optimal conditions, the signal intensity was linearly related to the concentration of SirT1 in the range of 1-500 ng ml(-1), and the limit of detection was 0.28 ng ml(-1). The developed biosensor exhibits attractive performance for the analysis of SirT1, with rapid response, high sensitivity, and high accuracy, and could become a promising technique for protein detection. PMID:27264194

  7. Fabrication of magnetic water-soluble hyperbranched polyol functionalized graphene oxide for high-efficiency water remediation

    Science.gov (United States)

    Hu, Lihua; Li, Yan; Zhang, Xuefei; Wang, Yaoguang; Cui, Limei; Wei, Qin; Ma, Hongmin; Yan, Liangguo; Du, Bin

    2016-06-01

    Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG adsorption process of MB, MV and Pb(II) was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where π-π stacking interactions, H-bonding interaction and electrostatic attraction dominated the adsorption of MB/MV and chelation and electrostatic attraction dominated the adsorption of Pb(II). In addition, the excellent reproducibility endowed MWHPO-GO with the potential for application in water remediation.

  8. Vegetable-Oil-Based Hyperbranched Polyester-Styrene Copolymer Containing Silver Nanoparticle as Antimicrobial and Corrosion-Resistant Coating Materials

    Directory of Open Access Journals (Sweden)

    Manawwer Alam

    2013-01-01

    Full Text Available Pongamia oil (PO was converted to Pongamia oil hydroxyl (POH via epoxidation process. The esterification of POH with linolenic acid was carried out to form hyperbranched polyester (HBPE, and further styrenation was performed at the conjugated double bond in the chain of linolenic acid. After styrenation, silver nanoparticle was added in different weight percentages (0.1–0.4 wt%. The structural elucidation of POH, HBPE, and HBPE-St was carried out by FT-IR, 1H-NMR, and 13C-NMR spectroscopic techniques. Physicochemical and physicomechanical analyses were performed by standard method. Thermal behavior of the HBPE-St was analyzed by using thermogravimetric analysis (TGA and differential scanning calorimetry (DSC. The coatings of HBPE-St were prepared on mild steel strips. The anticorrosive behavior of HBPE-St resin-based coatings in acid, saline, and tap water was evaluated, and the molecular weight of HBPE-St was determined by gel permeation chromatography (GPC. The antibacterial activities of the HBPE-St copolymers were tested in vitro against bacteria and fungi by disc diffusion method. The HBPE-St copolymers exhibited good antibacterial activities and can be used as antimicrobial and corrosion-resistant coating materials.

  9. Hyperbranched poly(glycidol)/poly(ethylene oxide) crosslinked hydrogel for tissue engineering scaffold using e-beams.

    Science.gov (United States)

    Haryanto; Singh, Deepti; Huh, Pil Ho; Kim, Seong Cheol

    2016-01-01

    A microporous hydrogel scaffold was developed from hyperbranched poly(glycidol) (HPG) and poly(ethylene oxide) (PEO) using electron beam (e-beam) induced cross-linking for tissue engineering applications. In this study, HPG was synthesized from glycidol using trimethylol propane as a core initiator and cross-linked hydrogels were made using 0, 10, 20, and 30% HPG with respect to PEO. The effects of %-HPG on the swelling ratio, cross-linking density, mechanical properties, morphology, degradation, and cytotoxicity of the hydrogel scaffolds were then investigated. Increasing the HPG content increased the pore size of the hydrogel scaffold, as well as the porosity, elongation at break, degree of degradation and swelling ratio. In contrast, the presence of HPG decreased the cross-linking density of the hydrogel. There was no significant difference in compressive modulus and tensile strength of all compositions. The pore size of hydrogel scaffolds could be easily tailored by controlling the content of HPG in the polymer blend. Evaluation of the cytotoxicity demonstrated that HPG/PEO hydrogel scaffold has potential for use as a matrix for cellular attachment and proliferation. These results indicate that cross-linked HPG/PEO hydrogel can function as a potential material for tissue engineering scaffolds. Moreover, a facile method to prepare hydrogel microporous scaffolds for tissue engineering by e-beam irradiation was developed.

  10. Change in size, morphology and stability of DNA polyplexes with hyperbranched poly(ethyleneimines) containing bulky maltose units.

    Science.gov (United States)

    Rumschöttel, Jens; Kosmella, Sabine; Prietzel, Claudia; Appelhans, Dietmar; Koetz, Joachim

    2016-02-01

    Polyplexes between Salmon DNA and non-modified hyperbranched poly(ethyleneimines) of varying molar mass, i.e., PEI(5 k) with 5000 g/mol and PEI(25 k) with 25,000 g/mol, and modified PEI(5 k) with maltose units (PEI-Mal) were investigated in dependence on the molar N/P ratio by using dynamic light scattering (DLS), zeta potential measurements, micro differential scanning calorimetry (μ-DSC), scanning-transmission electron microscopy (STEM), and cryo-scanning electron microscopy (cryo-SEM). A reloading of the polyplexes can be observed by adding the unmodified PEI samples of different molar mass. In excess of PEI a morphological transition from core-shell particles (at N/P 8) to loosely packed onion-like polyplexes (at N/P 40) is observed. The shift of the DSC melting peak from 88 °C to 76 °C indicates a destabilization of the DNA double helix due to the complexation with the unmodified PEI. Experiments with the maltose-modified PEI show a reloading already at a lower N/P ratio. Due to the presence of the sugar units in the periphery of the polycation electrostatic interactions between DNA become weaker, but cooperative H-bonding forces are reinforced. The resulting less-toxic, more compact polyplexes in excess of the PEI-Mal with two melting points and well distributed DNA segments are of special interest for extended gene delivery experiments.

  11. 电活性超支化聚合物的合成与性质%Synthesis and Properties of Electroactive Hyperbranched Polymer

    Institute of Scientific and Technical Information of China (English)

    晁单明; 姚雷; 陈大鹏; 何立兵; 贾晓腾; 刘洪涛; 王策

    2011-01-01

    通过分子设计,利用A2+B3反应合成了一种新型电活性超支化聚合物材料.该材料在保持聚苯胺的电活性基础上,还具有超支化聚合物特有的低黏度(其特性黏度为0.33 dL/g)、低结晶性及良好的溶解性.利用紫外-可见光谱对聚合物的氧化过程进行了监测.热失重分析显示,该材料具有较好的热稳定性,失重10%时的温度高达517℃.该材料具有较高的介电常数,有望成为一种具有实际应用价值的高介电材料.%We prepared an electroactive hyperbranched polymer containing phenyl-capped aniline tetramer segment in the chains by integration of A2 + B3 strategy with oxidative coupling polymerization. The structure of hyperbranched polymer was characterized by FTIR, 1H NMR spectra, and gel permeation chromatography (GPC). A reversible electrochemical property like common oligoanilines was found. The thermal properties and dielectric properties were also investigated. With an exciting structure, reversible electrochemical properties and dielectric properties, the electroactive hyperbranched polymer would be used as electromagnetic interference ( EMI) shielding and microwave absorbing materials in the future.

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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

  17. Supercontinuum generation and filamentation of ultrashort laser pulses in hybrid silicate nanocomposite materials on the basis of polysaccharides and hyperbranched polyglycidols

    Energy Technology Data Exchange (ETDEWEB)

    Kul' chin, Yurii N; Golik, S S; Proshenko, D Yu; Chekhlenok, A A; Postnova, I V; Maior, A Yu; Shchipunov, Yurii A

    2013-04-30

    The possibility of using hybrid silicate nanocomposite materials on the basis of polysaccharides and hyperbranched polyglycidols for efficient conversion of pulsed radiation of a femtosecond Ti : sapphire laser at the wavelength 800 nm into supercontinuum in the range from 400 to 1000 nm is experimentally demonstrated. It is established that the addition of a small concentration of Au and CdS nanoparticles to the studied materials essentially affects the efficiency of conversion of the laser radiation energy into the supercontinuum spectrum. (extreme light fields and their applications)

  18. Facile preparation of highly luminescent CdTe quantum dots within hyperbranched poly(amidoamine)s and their application in bio-imaging

    OpenAIRE

    Shi, Yunfeng; Liu, Lin; Pang, Huan; Zhou, Hongli; Zhang, Guanqing; Ou, Yangyan; Zhang, Xiaoyin; Du, Jimin; Xiao, Wangchuan

    2014-01-01

    A new strategy for facile preparation of highly luminescent CdTe quantum dots (QDs) within amine-terminated hyperbranched poly(amidoamine)s (HPAMAM) was proposed in this paper. CdTe precursors were first prepared by adding NaHTe to aqueous Cd2+ chelated by 3-mercaptopropionic sodium (MPA-Na), and then HPAMAM was introduced to stabilize the CdTe precursors. After microwave irradiation, highly fluorescent and stable CdTe QDs stabilized by MPA-Na and HPAMAM were obtained. The CdTe QDs showed a h...

  19. 端羟基超支化聚合物的合成与改性%Synthesis and modification of hydroxyl-terminated hyperbranched polymer

    Institute of Scientific and Technical Information of China (English)

    强涛涛; 张国国; 王学川

    2012-01-01

    An intermediate 4 - (bis(2 - hydroxy ethyl) imine) -4 -oxy butyric acid (hereinafter refers to as AB2) was synthesized from succinic anhydride and diethanol amine as starting materials. The AB2 was further reacted with trihydroxymethyl propane with p - toluene sulfonic acid as catalyst and toluene as water stripping agent to obtain hydroxyl - terminated hyperbranched poly ( amine - ester). Then the latter was modified with palmitoyl chloride to obtain hyperbranched polymer surfactant. On the basis of single - factor experiments, the optimum synthesis conditions for hydroxyl —terminated hyperbranched poly (amine - ester) were determined as follows;esterification reaction temperature, 120 ℃ ;reaction time,8 h;dosage of catalyst,3% (based on total mass of AB2 monomer). The molecular structure of the hydroxy — terminated hyperbranched poly ( amine — ester) products, both before and after the palmitoyl chloride modification were characterized by FTIR and 1HNMR. The surface activity of the final product was investigated by surface tension instruments, and the final product shows properties of a typical surfactant.%以丁二酸酐和二乙醇胺为起始原料通过加成反应合成AB2单体,将其与三羟甲基丙烷反应,在对甲苯磺酸催化下,甲苯为带水剂,通过酯化反应得到三代端羟基超支化聚(胺-酯),再以棕榈酰氯对其进行改性得到超支化聚(胺-酯)表面活性剂.通过单因素实验筛选出合成端羟基超支化聚合物较佳反应条件:反应温度120℃,反应时间8h,催化剂用量为3%(相对于AB2单体质量).利用FTIR和1HNMR对改性前后超支化聚(胺-酯)的分子结构进行了表征.通过表面张力仪对产物的表面活性进行了研究,结果表明合成的产物具有典型表面活性剂的性质.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. A label-free and high sensitive aptamer biosensor based on hyperbranched polyester microspheres for thrombin detection

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Chong [Jiangsu Key Laboratory of Biofunctional Materials, Biomedical Functional Materials Collaborative Innovation Center, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014 (China); Han, Qiaorong [Jiangsu Key Laboratory of Biofunctional Materials, Biomedical Functional Materials Collaborative Innovation Center, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Wang, Daoying; Xu, Weimin [Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014 (China); Wang, Weijuan [Jiangsu Key Laboratory of Biofunctional Materials, Biomedical Functional Materials Collaborative Innovation Center, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhao, Wenbo, E-mail: zhaowenbo@njnu.edu.cn [Jiangsu Key Laboratory of Biofunctional Materials, Biomedical Functional Materials Collaborative Innovation Center, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhou, Min, E-mail: zhouminnju@126.com [Department of Vascular Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China)

    2014-11-19

    Highlights: • A label-free thrombin aptamer biosensor applied in whole blood has been developed. • The aptamer biosensor showed a wide detection range and a low detection limit. • The antibiofouling idea utilized for biosensor is significant for diagnostics. - Abstract: In this paper, we have synthesized hyperbranched polyester microspheres with carboxylic acid functional groups (HBPE-CA) and developed a label-free electrochemical aptamer biosensor using thrombin-binding aptamer (TBA) as receptor for the measurement of thrombin in whole blood. The indium tin oxide (ITO) electrode surface modified with HBPE-CA microspheres was grafted with TBA, which has excellent binding affinity and selectivity for thrombin. Binding of the thrombin at the modified ITO electrode surface greatly restrained access of electrons for a redox probe of [Fe(CN){sub 6}]{sup 3−/4−}. Moreover, the aptamer biosensor could be used for detection of thrombin in whole blood, a wide detection range (10 fM–100 nM) and a detection limit on the order of 0.90 fM were demonstrated. Control experiments were also carried out by using bull serum albumin (BSA) and lysozyme in the absence of thrombin. The good stability and repeatability of this aptamer biosensor were also proved. We expect that this demonstration will lead to the development of highly sensitive label-free sensors based on aptamer with lower cost than current technology. The integration of the technologies, which include anticoagulant, sensor and nanoscience, will bring significant input to high-performance biosensors relevant to diagnostics and therapy of interest for human health.

  10. A label-free and high sensitive aptamer biosensor based on hyperbranched polyester microspheres for thrombin detection

    International Nuclear Information System (INIS)

    Highlights: • A label-free thrombin aptamer biosensor applied in whole blood has been developed. • The aptamer biosensor showed a wide detection range and a low detection limit. • The antibiofouling idea utilized for biosensor is significant for diagnostics. - Abstract: In this paper, we have synthesized hyperbranched polyester microspheres with carboxylic acid functional groups (HBPE-CA) and developed a label-free electrochemical aptamer biosensor using thrombin-binding aptamer (TBA) as receptor for the measurement of thrombin in whole blood. The indium tin oxide (ITO) electrode surface modified with HBPE-CA microspheres was grafted with TBA, which has excellent binding affinity and selectivity for thrombin. Binding of the thrombin at the modified ITO electrode surface greatly restrained access of electrons for a redox probe of [Fe(CN)6]3−/4−. Moreover, the aptamer biosensor could be used for detection of thrombin in whole blood, a wide detection range (10 fM–100 nM) and a detection limit on the order of 0.90 fM were demonstrated. Control experiments were also carried out by using bull serum albumin (BSA) and lysozyme in the absence of thrombin. The good stability and repeatability of this aptamer biosensor were also proved. We expect that this demonstration will lead to the development of highly sensitive label-free sensors based on aptamer with lower cost than current technology. The integration of the technologies, which include anticoagulant, sensor and nanoscience, will bring significant input to high-performance biosensors relevant to diagnostics and therapy of interest for human health

  11. Development of hyperbranched polymers with non-covalent interactions for extraction and determination of aflatoxins in cereal samples.

    Science.gov (United States)

    Liu, Xiaoyan; Li, Huihui; Xu, Zhigang; Peng, Jialin; Zhu, Shuqiang; Zhang, Haixia

    2013-10-01

    A novel approach for assembling homogeneous hyperbranched polymers based on non-covalent interactions with aflatoxins was developed; the polymers were used to evaluate the extraction of aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2) in simulant solutions. The results showed that the extraction efficiencies of three kinds of synthesized polymers for the investigated analytes were not statistically different; as a consequence, one of the representative polymers (polymer I) was used as the solid-phase extraction (SPE) sorbent to evaluate the influences of various parameters, such as desorption conditions, pH, ionic strength, concentration of methanol in sample solutions, and the mass of the sorbent on the extraction efficiency. In addition, the extraction efficiencies for these aflatoxins were compared between the investigated polymer and the traditional sorbent C18. The results showed that the investigated polymer had superior extraction efficiencies. Subsequently, the proposed polymer for the SPE packing material was employed to enrich and analyze four aflatoxins in the cereal powder samples. The limits of detection (LODs) at a signal-to-noise (S/N) ratio of 3 were in the range of 0.012-0.120 ng g(-1) for four aflatoxins, and the limits of quantification (LOQs) calculated at S/N=10 were from 0.04 to 0.40 ng g(-1) for four aflatoxins. The recoveries of four aflatoxins from cereal powder samples were in the range of 82.7-103% with relative standard deviations (RSDs) lower than 10%. The results demonstrate the suitability of the SPE approach for the analysis of trace aflatoxins in cereal powder samples.

  12. Development of hyperbranched polymers with non-covalent interactions for extraction and determination of aflatoxins in cereal samples.

    Science.gov (United States)

    Liu, Xiaoyan; Li, Huihui; Xu, Zhigang; Peng, Jialin; Zhu, Shuqiang; Zhang, Haixia

    2013-10-01

    A novel approach for assembling homogeneous hyperbranched polymers based on non-covalent interactions with aflatoxins was developed; the polymers were used to evaluate the extraction of aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2) in simulant solutions. The results showed that the extraction efficiencies of three kinds of synthesized polymers for the investigated analytes were not statistically different; as a consequence, one of the representative polymers (polymer I) was used as the solid-phase extraction (SPE) sorbent to evaluate the influences of various parameters, such as desorption conditions, pH, ionic strength, concentration of methanol in sample solutions, and the mass of the sorbent on the extraction efficiency. In addition, the extraction efficiencies for these aflatoxins were compared between the investigated polymer and the traditional sorbent C18. The results showed that the investigated polymer had superior extraction efficiencies. Subsequently, the proposed polymer for the SPE packing material was employed to enrich and analyze four aflatoxins in the cereal powder samples. The limits of detection (LODs) at a signal-to-noise (S/N) ratio of 3 were in the range of 0.012-0.120 ng g(-1) for four aflatoxins, and the limits of quantification (LOQs) calculated at S/N=10 were from 0.04 to 0.40 ng g(-1) for four aflatoxins. The recoveries of four aflatoxins from cereal powder samples were in the range of 82.7-103% with relative standard deviations (RSDs) lower than 10%. The results demonstrate the suitability of the SPE approach for the analysis of trace aflatoxins in cereal powder samples. PMID:24050668

  13. Sensing of environmental pollutant by conductive composite from prepared from hyperbranched polymer-grafted carbon black and crystalline polymer

    International Nuclear Information System (INIS)

    Complete text of publication follows. The hyperbranched (HB) polymer-grafted (PG) carbon blacks (CB) have the possibility of utilizing as a support of catalyst and enzyme, and a curing agent of epoxy resin, because they have much terminal amino or hydroxyl groups. The postgrafting of crystalline polymer onto HB PG CB and the sensing of environmental pollutant by the conductive composite prepared from the polymer-postgrafted CB was discussed. The grafting of poly(amidoamide) onto CB surface was achieved by repeating either Michael addition of methyl acrylate to amino group on the surface or the amidation of the resulting terminal methyl ester group with ethylene diamine. HB polyester onto CB surface was grafted by stepwise growth of 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) from surface carboxyl and hydroxyl groups on CB as a core in the presence of p-toluenesulfonic acid (p-TSA). The one-pot grafting of HB polyester onto CB as core was also achieved by the polycondensation of bis-MPA in the presence of p-TSA. Postgrafting of crystalline polymer onto HB polymer-grafted CB was achieved by the reaction of terminal amino or hydroxyl groups of grafted chain with COCl-terminated crystalline polymer. The electric resistance of the composite prepared from crystalline polymer-postgrafted CB was found to increase drastically in hexane, containing environmental pollutant, such as chloroform and trichloroethane, and returned immediately to the initial resistance when it was transferred into pure hexane. Based on the above results, it is concluded that the composite can be used as a novel sensor for environmental pollutant in solution

  14. 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

  15. 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

  16. 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

  17. 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

  18. Fabrication of glucose biosensor for whole blood based on Au/hyperbranched polyester nanoparticles multilayers by antibiofouling and self-assembly technique

    International Nuclear Information System (INIS)

    Highlight: •A novel method for detection of glucose in whole blood has been developed. •The method based on antibiofouling and self-assembly technology was investigated. •The antibiofouling technique utilized for sensor is significant for diagnostics. -- Abstract: Acknowledging the benefits of hyperbranched polymers and their nanoparticles, herein we report the design and synthesis of sulfonic acid group functionalized hydroxyl-terminated hyperbranched polyester (H30-SO3H) nanoparticles and their biomedical application. The H30-SO3H nanoparticles were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy (1H NMR). The good hemocompatibility of H30-SO3H nanoparticles was also investigated by coagulation tests, complement activation and platelet activation. The novel glucose biosensor was fabricated by immobilizing the positively charged Au nanoparticles, H30-SO3H nanoparticles and glucose oxidase (GOx) onto the surface of glassy carbon electrode (GCE). It can be applied in whole blood directly, which was based on the good hemocompatibility and antibiofouling property of H30-SO3H nanoparticles. The biosensor had good electrocatalytic activity toward glucose with a wide linear range (0.2–20 mM), a low detection limit 1.2 × 10−5 M in whole blood and good anti-interference property. The development of materials science will offer a novel platform for application to substance detection in whole blood

  19. Study on Modification of Hyperbranched Polyester Boltorn H20%超支化聚酯Boltorn H20的改性研究

    Institute of Scientific and Technical Information of China (English)

    王芳; 贾晓辉; 武亚新; 廖云

    2015-01-01

    The hyperbranched polyester Boltorn H20 contains a lot of hydroxyl groups,the reflux condensation method was adopted,some hydroxyl groups of H20 was modified with maleic anhydride,thereby some carboxyl groups were introduced in the H20. The effect of different solvents and modified hydroxyl number on the reaction time were discussed. Reac-tion end point was determined with FTIR,NMR spectroscopy confirmed that Boltorn H20 was successfully modified with maleic anhydride, this may be usefull for further study of hyperbranched polyester application on waterborne coatings.%超支化聚酯Boltorn H20分子末端含有很多羟基,采用回流冷凝法,用顺丁烯二酸酐将H20部分端羟基进行改性,从而在H20分子上引入了端羧基。主要讨论了溶剂和改性不同端羟基数目对反应的影响,反应终点采用红外光谱来确定。核磁共振谱图证实了Boltorn H20被成功改性,这为进一步研究超支化聚酯在水性涂料中的应用奠定了基础。

  20. Hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction for measurement of ibuprofen and naproxen in hair and waste water samples.

    Science.gov (United States)

    Rezaeifar, Zohreh; Es'haghi, Zarrin; Rounaghi, Gholam Hossein; Chamsaz, Mahmoud

    2016-09-01

    A new design of hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction (HBP/GO -HF-SLPME) coupled with high performance liquid chromatography used for extraction and determination of ibuprofen and naproxen in hair and waste water samples. The graphene oxide first synthesized from graphite powders by using modified Hummers approach. The surface of graphene oxide was modified using hyperbranched polyglycerol, through direct polycondensation with thionyl chloride. The ready nanocomposite later wetted by a few microliter of an organic solvent (1-octanol), and then applied to extract the target analytes in direct immersion sampling mode.After the extraction process, the analytes were desorbed with methanol, and then detected via high performance liquid chromatography (HPLC). The experimental setup is very simple and highly affordable. The main factors influencing extraction such as; feed pH, extraction time, aqueous feed volume, agitation speed, the amount of functionalized graphene oxide and the desorption conditions have been examined in detail. Under the optimized experimental conditions, linearity was observed in the range of 5-30,000ngmL(-1) for ibuprofen and 2-10,000ngmL(-1) for naproxen with correlation coefficients of 0.9968 and 0.9925, respectively. The limits of detection were 2.95ngmL(-1) for ibuprofen and 1.51ngmL(-1) for naproxen. The relative standard deviations (RSDs) were found to be less than 5% (n=5). PMID:27428449

  1. Fabrication of glucose biosensor for whole blood based on Au/hyperbranched polyester nanoparticles multilayers by antibiofouling and self-assembly technique

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Chong [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Key Laboratory for Soft Chemistry and Functional Materials of Ministry of Education, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Chen, Xiaohan; Han, Qiaorong [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhou, Min [Department of Vascular Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China); Mao, Chun, E-mail: maochun127@yahoo.cn [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhu, Qinshu [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Shen, Jian, E-mail: jshen@njnu.edu.cn [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China)

    2013-05-07

    Highlight: •A novel method for detection of glucose in whole blood has been developed. •The method based on antibiofouling and self-assembly technology was investigated. •The antibiofouling technique utilized for sensor is significant for diagnostics. -- Abstract: Acknowledging the benefits of hyperbranched polymers and their nanoparticles, herein we report the design and synthesis of sulfonic acid group functionalized hydroxyl-terminated hyperbranched polyester (H30-SO{sub 3}H) nanoparticles and their biomedical application. The H30-SO{sub 3}H nanoparticles were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy ({sup 1}H NMR). The good hemocompatibility of H30-SO{sub 3}H nanoparticles was also investigated by coagulation tests, complement activation and platelet activation. The novel glucose biosensor was fabricated by immobilizing the positively charged Au nanoparticles, H30-SO{sub 3}H nanoparticles and glucose oxidase (GOx) onto the surface of glassy carbon electrode (GCE). It can be applied in whole blood directly, which was based on the good hemocompatibility and antibiofouling property of H30-SO{sub 3}H nanoparticles. The biosensor had good electrocatalytic activity toward glucose with a wide linear range (0.2–20 mM), a low detection limit 1.2 × 10{sup −5} M in whole blood and good anti-interference property. The development of materials science will offer a novel platform for application to substance detection in whole blood.

  2. Achieving high performance electric field induced strain: a rational design of hyperbranched aromatic polyamide functionalized graphene-polyurethane dielectric elastomer composites.

    Science.gov (United States)

    Chen, Tian; Qiu, Jinhao; Zhu, Kongjun; Li, Jinhuan; Wang, Jingwen; Li, Shuqin; Wang, Xiaoliang

    2015-03-26

    Dielectric elastomers have great potentials as flexible actuators in micro-electromechanical systems (MEMS) due to their large deformation, light weight, mechanical compliancy, and low cost. The low dielectric constant of these elastomers requires a rather high voltage electric field, which has greatly limited their applications. In this work, a diaphragm-type flexible microactuator comprising a hyperbranched aromatic polyamide functionalized graphene (HAPFG) filler embedded into the polyurethane (PU) dielectric elastomer matrix is described. The rational designed HAPFG sheets exhibits uniform dispersion in PU matrix and strong adhesion with the matrix by hydrogen-bond coupling. Consequently, the HAPFG-PU composites possess high dielectric performance and low loss modulus. The effect of hyperbranched aromatic polyamide functionalized graphene on high voltage electric field induced strain was experimentally investigated using the Fotonic sensor. The high electric field response of the composite was discussed by applying different kinds of alternating-current field. In addition, a comparison of the breakdown strength between the HAPFG-PU composite and the pure PU was carried out. PMID:25741878

  3. Competitive and synergistic effects between excimer VUV radiation and O radicals on the etching mechanisms of polyethylene and fluoropolymer surfaces treated by atmospheric He-O$_2$ post-discharge

    CERN Document Server

    Dufour, Thierry; Vandencasteele, Nicolas; Viville, Pascal; Lazzaroni, Roberto; Reniers, François

    2016-01-01

    Among various surface modification techniques, plasma can be used as a source for tailoring the surface properties of diverse materials. HDPE and fluoropolymer surfaces have been treated by the post-discharge of an atmospheric RF-plasma torch supplied with helium and oxygen gases. The plasma-treated surfaces were characterized by measurements of mass losses, water contact angles, x-ray photoelectron spectroscopy and atomic force microscopy. This experimental approach correlated with an optical characterization of the plasma phase allowed us to propose etching mechanisms occurring at the post-discharge/polymer interface. We discuss how competitive and synergistic effects can result from the oxidation and/or the roughening of the surface but also from the excimer VUV radiation, the He metastable species and the O radicals reaching the plasma-polymer interface.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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)

  9. 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

  10. 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...

  11. 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...

  12. 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

  13. 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...

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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.

  19. Large organized surface domains self-assembled from nonpolar amphiphiles.

    Science.gov (United States)

    Krafft, Marie Pierre

    2012-04-17

    For years, researchers had presumed that Langmuir monolayers of small C(n)F(2n+1)C(m)H(2m+1) (FnHm) diblock molecules (such as F8H16) consisted of continuous, featureless films. Recently we have discovered that they instead form ordered arrays of unusually large (~30-60 nm), discrete self-assembled surface domains or hemimicelles both at the surface of water and on solid substrates. These surface micelles differ in several essential ways from all previously reported or predicted molecular surface aggregates. They self-assemble spontaneously, even at zero surface pressure, depending solely on a critical surface concentration. They are very large (~100 times the length of the diblock) and involve thousands of molecules (orders of magnitude more than classical micelles). At the same time, the surface micelles are highly monodisperse and self-organize in close-packed hexagonal patterns (two-dimensional crystals). Their size is essentially independent from pressure, and they do not coalesce and are unexpectedly sturdy for soft matter (persisting even beyond surface film collapse). We and other researchers have observed large surface micelles for numerous diblocks, using Langmuir-Blodgett (LB) transfer, spin-coating and dip-coating techniques, or expulsion from mixed monolayers, and on diverse supports, establishing that hemimicelle formation and ordering are intrinsic properties of (perfluoroalkyl)alkanes. Notably, they involve "incomplete" surfactants with limited amphiphilic character, which further illustrates the outstanding capacity for perfluoroalkyl chains to promote self-assembly and interfacial film structuring. Using X-ray reflectivity, we determined a perfluoroalkyl-chain-up orientation. Theoretical investigations assigned self-assembly and hemimicelle stability to electrostatic dipole-dipole interactions at the interface between Fn- and Hm-sublayers. Grazing-incidence small-angle X-ray scattering (GISAXS) data collected directly on the surface of water

  20. Structure and reactions in some amphiphilic association systems

    Science.gov (United States)

    Guo, Rong

    1999-06-01

    surfactant CTAB system with various co-surfactants: n-pentanol, n-octanol, n-valeric acid, and n-caproic acid, but not in SDS or Triton X-100 systems. Presence of VC stabilizes both W/O and O/W microemulsions but destabilizes the lamellar liquid crystalline phase. Hence, the "phase transition" from the lamellar liquid crystalline phase to the isotropic phase of O/W, W/O and bicontinuous structure phase occurs with the addition of VC. The hydrotropic action of VC has been used in sunscreens to increase the solubility of sunscreen E 557. The UV absorption spectra of E557 in various media surprisingly had a dependence on the colloid structure. A new method, the preparation of water-soluble nanoparticles, has been found by employing the effect of the penetration of solvent from water layer to amphiphilic layer in lamellar liquid crystals on the solubility of inorganic salts. Water-insoluble nanoparticles have been synthesized by the reaction of two water-soluble inorganic salts in the lamellar liquid crystal. The particle size is less than 10nm and can be controlled by the thickness of the solvent layer in the lamellar liquid crystal. The lamellar liquid crystalline phase of the Triton X-100/decanol/water system has been chosen as a medium because of its large lamellar liquid crystal region and its stability when inorganic salts are added.

  1. Adsorption of phthalic acid esters (PAEs) by amphiphilic polypropylene nonwoven from aqueous solution: the study of hydrophilic and hydrophobic microdomain.

    Science.gov (United States)

    Zhou, Xiangyu; Wei, Junfu; Zhang, Huan; Liu, Kai; Wang, Han

    2014-05-30

    A kind of amphiphilic polypropylene nonwoven with hydrophilic and hydrophobic microdomain was prepared through electron beam induced graft polymerization and subsequent ring opening reaction and then utilized in the adsorption of phthalic acid esters (PAEs). To elucidate the superiority of such amphiphilic microdomain, a unique structure without hydrophilic part was constructed as comparison. In addition, the adsorption behaviors including adsorption kinetics, isotherms and pH effect were systematically investigated. The result indicated that the amphiphilic structure and the synergy between hydrophilic and hydrophobic microdomain could considerably improve the adsorption capacities, rate and affinity. Particularly the existence of hydrophilic microdomain could reduce the diffusion resistance and energy barrier in the adsorption process. These adsorption results showed that the amphiphilic PP nonwoven have the potential to be used in environmental application.

  2. 新型超支化环氧丙烯酸酯的合成及表征%Synthesis and characterization of a novel hyperbranched epoxy acrylate

    Institute of Scientific and Technical Information of China (English)

    靳奇峰; 薛蕾; 陈欣; 佟丽娜; 姜冬月

    2015-01-01

    采用质子转移聚合法成功制备了超支化环氧树脂,并通过丙烯酸对其端基进行化学改性合成了一种新型的超支化环氧丙烯酸酯,采用 FTIR、1 H NMR 对产物结构进行了表征。通过控制投料比及测定产物酸值来监测反应进行的程度,使生成的超支化环氧丙烯酸酯中既含有环氧基又含有碳碳双键,使之兼具阳离子型光聚合与自由基型光聚合的协同作用。测试了超支化聚合物在氯仿中的紫外-可见光谱和荧光发射光谱,超支化环氧树脂和超支化环氧丙烯酸酯的荧光发射波谱出峰位置分别为314 nm 和311 nm。研究表明,超支化聚合物具有较强的荧光性能,作为光固化材料在光学、医疗器件、防伪等领域具有潜在的应用价值。%Hyperbranched epoxy resin(HBEP)was synthesized by proton transfer polymerization. And a novel structure hyperbranched epoxy acrylate(HBEA)containing both epoxy group and carbon-carbon double bond was synthesized by acrylic modified the HBEP. The structures of the polymer were character-ized by FTIR and 1 H NMR. The extent of the reaction was monitored by controlling the molar ratio and measuring the acid value. The results showed that the HBEA contained both epoxy group and carbon-car-bon double bond which can improve the performance of the material by the synergistic effect of the cation-ic photopolymerization and the radical photopolymerization. Hyperbranched polymers were characterized in chloroform by UV-Vis spectra and fluorescence emission spectra. The photoluminescent behavior renders these materials highly interesting as UV curing films in optical devices like light-emitting diodes and UV light detection systems as well as in anticounterfeiting applications.

  3. Photophysical and photochemical studies of a novel amphiphilic zinc phthalocyanine and its interaction with calf thymus DNA

    Science.gov (United States)

    Yuan, Linxin; Gui, Li; Wang, Yue; Zhang, Quanquan; Zhou, Lin; Wei, Shaohua

    2016-04-01

    β-tetra (aminophenoxy) sulfonic substituted zinc phthalocyanines (SNZnPc), a novel amphiphilic zinc phthalocyanine (Pc), was synthesized. The photophysical, photochemical, and photobiology properties were studied. Results indicated that the synthesized SNZnPc has good amphiphilic property and high reactive oxygen species (ROSs) generation ability. Furthermore, SNZnPc has strong affinity to calf thymus DNA (CT-DNA) through intercalation ways and can effectively cleavage CT-DNA after irradiation by light with appropriate wavelength.

  4. 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...

  5. Synthesis of a new generation of amphiphiles with multi-cryptand headgroups: A comparative study at air–water interface

    Indian Academy of Sciences (India)

    B Sarkar; R K Gupta; R A Singh; P K Bharadwaj

    2008-06-01

    A laterally non-symmetric aza cryptand has been derivatized with two hydrophobic chains to afford amphiphiles with one cryptand headgroup and two hydrophobic tails. Three such units readily attach to 1,3,5-benzenetricarbonyl trichloride, to form a new generation of amphiphilic molecules with three cryptand headgroups and six hydrophobic chains. These molecules are studied at the air–water interface in a Langmuir trough. They readily form LB-films on a number of substrates that are characterized.

  6. Photophysical and photochemical studies of a novel amphiphilic zinc phthalocyanine and its interaction with calf thymus DNA.

    Science.gov (United States)

    Yuan, Linxin; Gui, Li; Wang, Yue; Zhang, Quanquan; Zhou, Lin; Wei, Shaohua

    2016-04-01

    β-tetra (aminophenoxy) sulfonic substituted zinc phthalocyanines (SNZnPc), a novel amphiphilic zinc phthalocyanine (Pc), was synthesized. The photophysical, photochemical, and photobiology properties were studied. Results indicated that the synthesized SNZnPc has good amphiphilic property and high reactive oxygen species (ROSs) generation ability. Furthermore, SNZnPc has strong affinity to calf thymus DNA (CT-DNA) through intercalation ways and can effectively cleavage CT-DNA after irradiation by light with appropriate wavelength.

  7. Adsorption of phthalic acid esters (PAEs) by amphiphilic polypropylene nonwoven from aqueous solution: The study of hydrophilic and hydrophobic microdomain

    International Nuclear Information System (INIS)

    Highlights: • Amphiphilic PP-g-GMA-OA nonwoven was prepared and characterized. • Synergy between hydrophilic and hydrophobic microdomain was elucidated. • The effects of hydrophilic microdomain on diffusion resistance and energy barrier were elucidated. • Adsorbent material with amphiphilic structures showed faster adsorption rate and lager adsorption capacity. - Abstract: A kind of amphiphilic polypropylene nonwoven with hydrophilic and hydrophobic microdomain was prepared through electron beam induced graft polymerization and subsequent ring opening reaction and then utilized in the adsorption of phthalic acid esters (PAEs). To elucidate the superiority of such amphiphilic microdomain, a unique structure without hydrophilic part was constructed as comparison. In addition, the adsorption behaviors including adsorption kinetics, isotherms and pH effect were systematically investigated. The result indicated that the amphiphilic structure and the synergy between hydrophilic and hydrophobic microdomain could considerably improve the adsorption capacities, rate and affinity. Particularly the existence of hydrophilic microdomain could reduce the diffusion resistance and energy barrier in the adsorption process. These adsorption results showed that the amphiphilic PP nonwoven have the potential to be used in environmental application

  8. 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.

  9. Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene.

    Science.gov (United States)

    Lumholdt, Ludmilla; Fourmentin, Sophie; Nielsen, Thorbjørn T; Larsen, Kim L

    2014-01-01

    Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances) were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixture containing multiple pollutants. The volatile organic compounds are known to form stable inclusion complexes with cyclodextrins. Six different amphiphilic cyclodextrin derivatives were synthesised in order to elucidate whether or not the uptake abilities of the coating depend on the structure of the derivative. Headspace gas chromatography was used for quantification of the uptake exploiting the volatile nature of benzene and its derivatives. The capacity was shown to increase beyond the expected stoichiometries of guest-host complexes with ratios of up to 16:1. PMID:25550739

  10. 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.

  11. Trapping of polycyclic aromatic hydrocarbons by amphiphilic cyclodextrin functionalized polypropylene nonwovens

    DEFF Research Database (Denmark)

    Lumholdt, Ludmilla; Nielsen, Ronnie Bo Højstrup; Larsen, Kim Lambertsen

    Recently, there has been an augmented focus on the increasing amount of pesticides, drug residues and endocrine disruptors present in waste and drinking water1. These pollutants represent a challenge in water purification since they may be hazardous to human health even in low doses2. Cyclodextrins...... of the textile fibers. In this study we present the ability of amphiphilic CD coated polypropylene nonwovens to trap 8 different polycyclic aromatic hydrocarbons/endocrine disruptors from aqueous solutions thus demonstrating the potential of using the amphiphilic cyclodextrins for water purification....... (CDs) are known to be able to form inclusion complexes with a large range of the unwanted pollutantse.g. 3 but in order to utilise this ability to purify water, the CDs must be immobilised on a surface, for instance, a membrane filter. We have developed a simple and fast method...

  12. 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

  13. REVIEWS OF TOPICAL PROBLEMS: Supermolecular liquid-crystalline structures in solutions of amphiphilic molecules

    Science.gov (United States)

    Vedenov, A. A.; Levchenko, E. B.

    1983-09-01

    This paper reviews the physical properties of liquid-crystalline phases arising in solutions containing molecules of amphiphilic substances. The basic characteristics of micelle formation in dilute solutions, models of sphere-disk or sphere-cylinder structural transformations, as well as phase transitions related to the appearance of lyotropic mesophases in the system, including nematic, lamellar, hexagonal, and others, are examined. The results of experimental and theoretical investigation of "solvation" forces acting between micelles in the solvent, as well as recently studied models of swelling of lamellar phases are presented. The phenomena occurring near the inversion point of microemulsions in amphiphile-oil-water systems are examined briefly. The role of liquid-crystalline ordering in some biological systems is discussed.

  14. 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.

  15. Micelle assembly. Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles.

    Science.gov (United States)

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

    2015-03-20

    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. PMID:25792323

  16. Super-resolution microscopy reveals structural diversity in molecular exchange among peptide amphiphile nanofibres

    Science.gov (United States)

    da Silva, Ricardo M. P.; van der Zwaag, Daan; Albertazzi, Lorenzo; Lee, Sungsoo S.; Meijer, E. W.; Stupp, Samuel I.

    2016-05-01

    The dynamic behaviour of supramolecular systems is an important dimension of their potential functions. Here, we report on the use of stochastic optical reconstruction microscopy to study the molecular exchange of peptide amphiphile nanofibres, supramolecular systems known to have important biomedical functions. Solutions of nanofibres labelled with different dyes (Cy3 and Cy5) were mixed, and the distribution of dyes inserting into initially single-colour nanofibres was quantified using correlative image analysis. Our observations are consistent with an exchange mechanism involving monomers or small clusters of molecules inserting randomly into a fibre. Different exchange rates are observed within the same fibre, suggesting that local cohesive structures exist on the basis of β-sheet discontinuous domains. The results reported here show that peptide amphiphile supramolecular systems can be dynamic and that their intermolecular interactions affect exchange patterns. This information can be used to generate useful aggregate morphologies for improved biomedical function.

  17. AMPHIPHILIC STAR-BLOCK COPOLYMERS BY IODIDE-MEDIATED RADICAL POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Amphiphilic star-block copolymers composed of polystyrene and poly(acrylic acid) were synthesized by iodidemediated radical polymerization. Firstly, free radical polymerization of styrene was carried out with AIBN as initiator and 1,1,1-trimethyolpropane tri(2-iodoisobutyrate) as chain transfer agent, giving iodine atom ended star-shaped polystyrene with three arm chains, R(polystyrene)3. Secondly, tert-butyl acrylate was polymerization using polystyrene obtained as macro-chain transfer agent, and star-block copolymer, R(polystyrene-b-poly(tert-butyl acrylate))3 with controlled molecular weight was obtained. Finally, amphiphilic star-block copolymer, R(polystyrene-b-poly(acrylic acid))3 was obtained by hydrolysis of R(polystyrene-b-poly(tert-butyl acrylate))3 under acidic condition.

  18. 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.

  19. Replication of simulated prebiotic amphiphile vesicles controlled by experimental lipid physicochemical properties

    International Nuclear Information System (INIS)

    We present a new embodiment of the graded autocatalysis replication domain (GARD) for the growth, replication and evolution of lipid vesicles based on a semi-empirical foundation using experimentally measured kinetic values of selected extant lipid species. Extensive simulations using this formalism elucidated the details of the dependence of the replication and properties of the vesicles on the physicochemical properties and concentrations of the lipids, both in the environment and in the vesicle. As expected, the overall concentration and number of amphiphilic components strongly affect average replication time. Furthermore, variations in acyl chain length and unsaturation of vesicles also influence replication rate, as do the relative concentrations of individual lipid types. Understanding of the dependence of replication rates on physicochemical parameters opens a new direction in the study of prebiotic vesicles and lays the groundwork for future studies involving the competition between lipid vesicles for available amphiphilic monomers

  20. 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).

  1. 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.)

  2. 超支化聚酯季铵盐的合成与表征%Synthesis and characterization of quaternary ammonium salt of hyperbranched polyester

    Institute of Scientific and Technical Information of China (English)

    杜英英; 陈倩兰; 邢彦军; 戴瑾瑾

    2011-01-01

    In the presence of alkaline catalyst sodium hydroxide, quaternary ammonium salt of hyperbranched polyester (GTA-H20) was prepared by the modification of hyperbranched polyester Boltorn H20 with glycidyltrimethylammonium chloride (GTA).The influences of reaction conditions on the yield of product were studied.The results showed that under the conditions of n(H20):n(GTA)=1 :16, n(NaOH)/n(H20-OH)=0.5, 50 ℃ of reaction temperature and 24 h of reaction time, the product 61.11 % of yield was obtained.The element analysis indicated that the substitution degree of GTA was 22.32%, and the structure of the product was characterized by iH NMH,FT-IR and 13C NMR.%在氢氧化钠催化条件下,利用缩水甘油三甲基氯化铵(GTA)对端羟基超支化聚酯Boltom H20进行季铵化改性,得到了超支化聚酯季铵盐GTA-H20,研究了反应条件对产率的影晌,结果表明:当n(H20):n(GTA)=1:16,n(NaOH)/n(H20-OH)=0.5,50℃反应24h,产率为61.11%.元素分析结果表明:此时GTA的取代度为22.32%,并用(1)H NMR、FF-IR和(13)C NMR谱图对GTA-H20进行了表征.

  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. 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

  5. Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene

    OpenAIRE

    Ludmilla Lumholdt; Sophie Fourmentin; Nielsen, Thorbjørn T; Larsen, Kim L.

    2014-01-01

    Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances) were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixt...

  6. Amphiphilic zein hydrolysate as a novel nano-delivery vehicle for curcumin.

    Science.gov (United States)

    Wang, Yong-Hui; Wang, Jin-Mei; Yang, Xiao-Quan; Guo, Jian; Lin, Yuan

    2015-08-01

    In this paper, we developed amphiphilic zein hydrolysate (ZH) as a novel delivery vehicle, which could be used for preparing curcumin (Cur) nanocomplexes. These ZH-Cur nanocomplexes exhibited spherical morphology with a monodisperse size distribution (oil-water interface, as confirmed by micelle formation and dynamic interfacial adsorption respectively. Fluorescence titration and FTIR results indicated the existence of strong hydrophobic interactions between ZH and Cur, which was responsible for the complexation. PMID:26134524

  7. 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...

  8. Extracellular matrix formation in self-assembled minimalistic bioactive hydrogels based on aromatic peptide amphiphiles

    OpenAIRE

    ZHOU, MI; Ulijn, Rein V.; Gough, Julie E

    2014-01-01

    The hitherto inconsistency in clinical performance for engineered skin drives the current development of novel cell-scaffolding materials; one challenge is to only extract essential characteristics from the complex native ECM (extracellular matrix) and incorporate them into a scaffold with minimal complexity to support normal cell functions. This study involved small-molecule-based bioactive hydrogels produced by the co-assembly of two aromatic peptide amphiphiles: Fmoc-FF (Fluorenylmethoxyca...

  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. Langmuir-Blodgett Films and Calcium Ion Coordination of Biliverdin and Its Amphiphilic Derivatives

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Monolayer formation and LB film fabrication of amphiphilic derivative of biliverdin 1,diododecyl biliverdinamide [B(CONHC12H25)2,2] at an air-water interface on pure water subphase and subphase containing calcium ion were investigated and compared with 1.The coordination in ordered molecular films is much different from that in bulk solution.The formation of ligand-calcium complex was confirmed by X-ray photoelectron spectroscopy.

  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. 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...

  13. Aggregate of Amphiphilic Block Copolymer as a Pseudo-Stationary Phase in Capillary Electrophoresis

    OpenAIRE

    Nakamura, Tohru; OHKI, Akira; Mishiro, Masaki; Tsuyashima, Osamu; Maeda, Shigeru; ナカムラ, トオル; オオキ, アキラ; ミシロ, マサキ; ツヤシマ, オサム; マエダ, シゲル; 中村, 透; 大木, 章; 艶島, 修; 前田, 滋

    1999-01-01

    The use of an aggregate of amphiphilic block copolymer 1, which consists of poly[(N-acetylimino)ethylene] and poly[(N-pentanoylimino)ethylene], for a pseudo-stationary phase in capillary electrophoresis has been examined. From gel-filtration chromatography, the aggregate from 1 (1-AG) was found to incorporate phenol. When the running solution contains 1-AG and sodium dodecyl sulfate (SDS), the electrophoretic mobility becomes nearly zero. Thus, it is found that when 1-AG and SDS are added to ...

  14. Synthesis, Characterization, and Aqueous Lubricating Properties of Amphiphilic Graft Copolymers Comprising 2-Methoxyethyl Acrylate

    DEFF Research Database (Denmark)

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

    2014-01-01

    reversible addition–fragmentation chain transfer (RAFT) polymerization, copper-mediated atom transfer radical polymerization (ATRP), and a selective deprotection reaction. Initially, multifunctional ATRP macroinitiators based on PHEMA backbone are prepared by RAFT polymerization. Then ATRP......Amphiphilic anionic and cationic graft copolymers possessing poly(2-hydroxyethyl methacrylate) (PHEMA) backbone and poly(methacrylic acid), poly(2-methoxyethyl acrylate-co-methacrylic acid), and poly(2-methoxyethyl acrylate-co-2-(dimethylamino)ethyl methacrylate) grafts are constructed by merging...

  15. Synthesis and self-assembly of multiple thermoresponsive amphiphilic block copolymers

    OpenAIRE

    Weiß, Jan

    2011-01-01

    In the present thesis, the self-assembly of multi thermoresponsive block copolymers in dilute aqueous solution was investigated by a combination of turbidimetry, dynamic light scattering, TEM measurements, NMR as well as fluorescence spectroscopy. The successive conversion of such block copolymers from a hydrophilic into a hydrophobic state includes intermediate amphiphilic states with a variable hydrophilic-to-lipophilic balance. As a result, the self-organization is not following an all-or-...

  16. Novel amphiphilic diblock copolymers by RAFT-polymerization, their self-organization and surfactant properties

    OpenAIRE

    Garnier, Sébastien

    2006-01-01

    The Reversible Addition Fragmentation Chain Transfer (RAFT) process using the new RAFT agent benzyldithiophenyl acetate is shown to be a powerful polymerization tool to synthesize novel well-defined amphiphilic diblock copolymers composed of the constant hydrophobic block poly(butyl acrylate) and of 6 different hydrophilic blocks with various polarities, namely a series of non-ionic, non-ionic comb-like, anionic and cationic hydrophilic blocks. The controlled character of the polymerizations ...

  17. Exploring single chain amphiphile self-assembly and their possible roles in light transduction

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain

    2011-01-01

    Self-assembled structures of single-chain amphiphiles have been used as hosts for biochemical, and chemical reactions. Their use as models for protocells (i.e., precursors to the first biological cells) has been extensively researched by various groups because the availability of single chain amp...... network. References 1 Cape, J., et al. (2011) Chem. Sci., 2 (4), 661-667. 2 Maurer, S. E., et al. (2009) Astrobiology, 9, 979-987. 3 Caschera, F., et al. Langmuir, In press....

  18. 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...

  19. Elisapterosin F: a polycyclic gorgonian-derived diterpene with a facially amphiphilic structure

    Science.gov (United States)

    Rodríguez, Ileana I.; Rodríguez, Abimael D.

    2009-01-01

    Analysis of the terpene metabolites of Pseudopterogorgia elisabethae collected in San Andrés island, Colombia has resulted in the discovery of a novel metabolite, elisapterosin F (1). The tangled molecular structure of 1, which was elucidated after extensive spectroscopic data interpretation, possesses hydrophilic and hydrophobic groups located on two opposite faces, rather than at two ends as in the more conventional head/tail amphiphiles. PMID:20161151

  20. Carboxymethyl chitosan-graft-phosphatidylethanolamine : amphiphilic matrices for controlled drug delivery

    OpenAIRE

    Prabaharan, M.; Reis, R. L.; Mano, J. F.

    2007-01-01

    Modified carboxymethyl chitosan (CMC) containing phosphatidylethanolamine (PEA) groups were synthesized by a 1- ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)-mediated coupling reaction. The structure of the modified CMC exhibiting an amphiphilic character was analysed by FT-IR and 1H NMR. CMC-g-PEA beads were prepared with sodium tripolyphosphate (TPP) by ionic-crosslinking. The beads sizes were in range from 800 to 1200 lm and encapsulation efficiencies of drug were more than...

  1. 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.

  2. A comparative study of the physicochemical properties of perfluorinated and hydrogenated amphiphiles.

    Science.gov (United States)

    Blanco, Elena; González-Pérez, Alfredo; Ruso, Juan M; Pedrido, Rosa; Prieto, Gerardo; Sarmiento, Félix

    2005-08-01

    In this work we studied and compared the physicochemical properties of perfluorinated (sodium perfluoroheptanoate, C7FONa, and perfluorooctanoate, C8FONa) and hydrogenated (sodium octanoate, C8HONa, decanoate, C10HONa, and dodecanoate, C12HONa) amphiphiles. First, we determined their Krafft points to study the solubility and appropriate temperature range of micellization of these compounds. The critical micelle concentration (cmc) and ionization degree of micellization (beta) as a function of temperature (T) were estimated from conductivity data. Plots of cmc vs T appear to follow the typical U-shaped curve with a minimum T(min). The results show that the surfactants with CF2/CH2 ratio of 1.5 between alkyl chains (C12HONa-C8FONa and C10HONa-C7FONa) have nearly the same minimum value for cmc against temperature. The comparison between the cmc of hydrogenated amphiphiles and the corresponding perfluorinated amphiphiles must be done at this point. Thermodynamic functions of micellization were obtained by applying different theoretical models and choosing the one that best fit our experimental data. Although perfluorinated and hydrogenated amphiphiles present similar thermodynamic behavior, we have found a variation of 1.3 to 1.7 in the CF2/CH2 ratio, which did not remain constant with temperature. In the second part of this study the apparent molar volumes and adiabatic compressibilities were determined from density and ultrasound velocity measurements. Apparent molar volumes at infinite dilution presented the ratio 1.5 between alkyl chains again. However, apparent molar volumes upon micellization for sodium perfluoroheptanoate indicated a different aggregation pattern.

  3. 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.

  4. Ultrasound-driven secondary self-assembly of amphiphilic β-cyclodextrin dimers.

    Science.gov (United States)

    Zhang, Hai-tao; Fan, Xiao-dong; Tian, Wei; Suo, Rong-tian; Yang, Zhen; Bai, Yang; Zhang, Wan-bin

    2015-03-23

    The controlled secondary self-assembly of amphiphilic molecules in solution is theoretically and practically significant in amphiphilic molecular applications. An amphiphilic β-cyclodextrin (β-CD) dimer, namely LA-(CD)2 , has been synthesized, wherein one lithocholic acid (LA) unit is hydrophobic and two β-CD units are hydrophilic. In an aqueous solution at room temperature, LA-(CD)2 self-assembles into spherical micelles without ultrasonication. The primary micelles dissociates and then secondarily form self-assemblies with branched structures under ultrasonication. The branched aggregates revert to primary micelles at high temperature. The ultrasound-driven secondary self-assembly is confirmed by transmission electron microscopy, dynamic light scattering, (1) H NMR spectroscopy, and Cu(2+) -responsive experiments. Furthermore, 2D NOESY NMR and UV/Vis spectroscopy results indicate that the formation of the primary micelles is driven by hydrophilic-hydrophobic interactions, whereas host-guest interactions promote the formation of the secondary assemblies. Additionally, ultrasonication is shown to be able to effectively destroy the primary hydrophilic-hydrophobic balances while enhancing the host-guest interaction between the LA and β-CD moieties at room temperature. PMID:25581876

  5. Self-Assembly of Discrete Metal Complexes in Aqueous Solution via Block Copolypeptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Timothy J. Deming

    2013-01-01

    Full Text Available The integration of discrete metal complexes has been attracting significant interest due to the potential of these materials for soft metal-metal interactions and supramolecular assembly. Additionally, block copolypeptide amphiphiles have been investigated concerning their capacity for self-assembly into structures such as nanoparticles, nanosheets and nanofibers. In this study, we combined these two concepts by investigating the self-assembly of discrete metal complexes in aqueous solution using block copolypeptides. Normally, discrete metal complexes such as [Au(CN2]−, when molecularly dispersed in water, cannot interact with one another. Our results demonstrated, however, that the addition of block copolypeptide amphiphiles such as K183L19 to [Au(CN2]− solutions induced one-dimensional integration of the discrete metal complex, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Transmission electron microscopy (TEM showed a fibrous nanostructure with lengths and widths of approximately 100 and 20 nm, respectively, which grew to form advanced nanoarchitectures, including those resembling the weave patterns of Waraji (traditional Japanese straw sandals. This concept of combining block copolypeptide amphiphiles with discrete coordination compounds allows the design of flexible and functional supramolecular coordination systems in water.

  6. 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

  7. Intrinsically disordered amphiphilic peptides as potential targets in drug delivery vehicles.

    Science.gov (United States)

    Vincenzi, Marian; Accardo, Antonella; Costantini, Susan; Scala, Stefania; Portella, Luigi; Trotta, Annamaria; Ronga, Luisa; Guillon, Jean; Leone, Marilisa; Colonna, Giovanni; Rossi, Filomena; Tesauro, Diego

    2015-11-01

    Intrinsically disordered proteins/peptides play a crucial role in many physiological and pathological events and may assume a precise conformation upon binding to a specific target. Recently, we have described the conformational and functional properties of two linear ester peptides provided with the following sequences: Y-G-E-C-P-C-K-OAllyl (PepK) and Y-G-E-C-P-C-E-OAllyl (PepE). Both peptides are characterized by the presence of the "CPC" motif together with a few amino acids able to promote disorder. The CPC sequence is a binding motif for the CXCR4 receptor that represents a well-known target for cancer therapies. In this paper, we report on synthetic amphiphilic peptides that consist of lipophilic derivatives of PepE and PepK bearing two stearic alkyl chains and/or an ethoxylic spacer. These peptide amphiphiles form stable supramolecular aggregates; they present conformational features that are typical of intrinsically disordered molecules as shown by CD spectroscopy. Solution fluorescence and DLS studies have been performed to evaluate Critical Micellar Concentrations and the dimension of supramolecular aggregates. Moreover, preliminary in vitro cell-based assays have been conducted to investigate the molecular recognition processes involving the CXCR4 receptor. In the end, the results obtained have been compared with the previous data generated by the corresponding non-amphiphilic peptides (PepE and PepK). PMID:26263446

  8. New Amphiphilic Polypyridyl Ruthenium(Ⅱ) Sensitizer and Its Application in Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    KONG Fan-Tai; DAI Song-Yuan; WANG Kong-Jia

    2007-01-01

    Amphiphilic polypyridyl ruthenium(Ⅱ) complex cis-di(isothiocyanato)(4,4'-di-tert-butyl-2,2'-bipyridyl)(4,4'-dicarboxy-2,2'-bipyridyl)ruthenium(Ⅱ) (K005) has been synthesized and characterized by cyclic voltammetry, 1H NMR, UV-Vis, and FT-IR spectroscopies. The sensitizer sensitizes TiO2 over a notably broad spectral range due to its intense metal-to-ligand charge-transfer (MLCT) bands at 537 and 418 nm. The photophysical and photochemical studies of K005 were contrasted with those of cis-Ru(dcbpy)2(NCS)2, known as the N3 dye, and the amphiphilic ruthenium(Ⅱ) dye Z907. A reversible couple at E1/2=0.725 V vs. saturated calomel electrode (SCE) with a separation of 0.08 V between the anodic and cathodic peaks, was observed due to the RuⅡ/Ⅲ couple by cyclic voltammetry.Furthermore, this amphiphilic ruthenium complex was successfully used as sensitizers for dye-sensitized solar cells with the efficiency of 3.72% at the 100 mW·cm-2 irradiance of air mass 1.5 simulated sunlight without optimization of TiO2 films and the electrolyte.

  9. 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.

  10. A Phytic Acid Induced Super-Amphiphilic Multifunctional 3D Graphene-Based Foam.

    Science.gov (United States)

    Song, Xinhong; Chen, Yiying; Rong, Mingcong; Xie, Zhaoxiong; Zhao, Tingting; Wang, Yiru; Chen, Xi; Wolfbeis, Otto S

    2016-03-14

    Surfaces with super-amphiphilicity have attracted tremendous interest for fundamental and applied research owing to their special affinity to both oil and water. It is generally believed that 3D graphenes are monoliths with strongly hydrophobic surfaces. Herein, we demonstrate the preparation of a 3D super-amphiphilic (that is, highly hydrophilic and oleophilic) graphene-based assembly in a single-step using phytic acid acting as both a gelator and as a dopant. The product shows both hydrophilic and oleophilic intelligence, and this overcomes the drawbacks of presently known hydrophobic 3D graphene assemblies. It can absorb water and oils alike. The utility of the new material was demonstrated by designing a heterogeneous catalytic system through incorporation of a zeolite into its amphiphilic 3D scaffold. The resulting bulk network was shown to enable efficient epoxidation of alkenes without prior addition of a co-solvent or stirring. This catalyst also can be recovered and re-used, thereby providing a clean catalytic process with simplified work-up. PMID:26890034

  11. The search for new amphiphiles: synthesis of a modular, high-throughput library

    Directory of Open Access Journals (Sweden)

    George C. Feast

    2014-07-01

    Full Text Available Amphiphilic compounds are used in a variety of applications due to their lyotropic liquid-crystalline phase formation, however only a limited number of compounds, in a potentially limitless field, are currently in use. A library of organic amphiphilic compounds was synthesised consisting of glucose, galactose, lactose, xylose and mannose head groups and double and triple-chain hydrophobic tails. A modular, high-throughput approach was developed, whereby head and tail components were conjugated using the copper-catalysed azide–alkyne cycloaddition (CuAAC reaction. The tails were synthesised from two core alkyne-tethered intermediates, which were subsequently functionalised with hydrocarbon chains varying in length and degree of unsaturation and branching, while the five sugar head groups were selected with ranging substitution patterns and anomeric linkages. A library of 80 amphiphiles was subsequently produced, using a 24-vial array, with the majority formed in very good to excellent yields. A preliminary assessment of the liquid-crystalline phase behaviour is also presented.

  12. Intrinsically disordered amphiphilic peptides as potential targets in drug delivery vehicles.

    Science.gov (United States)

    Vincenzi, Marian; Accardo, Antonella; Costantini, Susan; Scala, Stefania; Portella, Luigi; Trotta, Annamaria; Ronga, Luisa; Guillon, Jean; Leone, Marilisa; Colonna, Giovanni; Rossi, Filomena; Tesauro, Diego

    2015-11-01

    Intrinsically disordered proteins/peptides play a crucial role in many physiological and pathological events and may assume a precise conformation upon binding to a specific target. Recently, we have described the conformational and functional properties of two linear ester peptides provided with the following sequences: Y-G-E-C-P-C-K-OAllyl (PepK) and Y-G-E-C-P-C-E-OAllyl (PepE). Both peptides are characterized by the presence of the "CPC" motif together with a few amino acids able to promote disorder. The CPC sequence is a binding motif for the CXCR4 receptor that represents a well-known target for cancer therapies. In this paper, we report on synthetic amphiphilic peptides that consist of lipophilic derivatives of PepE and PepK bearing two stearic alkyl chains and/or an ethoxylic spacer. These peptide amphiphiles form stable supramolecular aggregates; they present conformational features that are typical of intrinsically disordered molecules as shown by CD spectroscopy. Solution fluorescence and DLS studies have been performed to evaluate Critical Micellar Concentrations and the dimension of supramolecular aggregates. Moreover, preliminary in vitro cell-based assays have been conducted to investigate the molecular recognition processes involving the CXCR4 receptor. In the end, the results obtained have been compared with the previous data generated by the corresponding non-amphiphilic peptides (PepE and PepK).

  13. 超支化嗪胺化合物的合成及其作为防水剂在纺织品上的应用%Synthesis of hyperbranched triazine polymers and application in water repellency finishing of textiles

    Institute of Scientific and Technical Information of China (English)

    苏勇; 叶林宇; 刘波; 吴阿亮

    2016-01-01

    采用三聚氯氰为核,对称二元胺为连接单元,棕榈基仲胺为外围改性基团合成具有拒水性能的超支化嗪胺化合物,并通过1H NMR和13C NMR对其结构进行表征,研究了其在棉织物上的防水效果,经聚乙二醇改性的二代超支化聚合物13在棉织物上的拒水性能可达4级以上。%The hyperbranched polymers containing triazine with water repel ency were synthesized using cyanuric chloride as core, diamine as linkage unit and palmityls as the periphery modifying group. And the structure of the hyperbranched polymer was determined by 1H NMR and 13C NMR. The application of the hy⁃perbranched polymers in water repel ency finishing of textile was studied. The results showed that the hydro⁃philic group MPEG modified hyperbranched polymers showing good water repel ency performance (grade 4) on cotton fabric.

  14. Peptide-based gemini amphiphiles: phase behavior and rheology of wormlike micelles.

    Science.gov (United States)

    Shrestha, Rekha Goswami; Nomura, Kazuyuki; Yamamoto, Masashi; Yamawaki, Yukio; Tamura, Yoshinaga; Sakai, Kenichi; Sakamoto, Kazutami; Sakai, Hideki; Abe, Masahiko

    2012-11-01

    Aqueous binary phase behavior of a peptide-based gemini amphiphile with glutamic acid and lysine as spacer group, acylglutamyllysilacylglutamate (m-GLG-m where m = 12, 14, and 16), has been reported over a wide range of concentration and temperature. Lauroylglutamyllysillauroylglutamate, 12-GLG-12, self-assembles into spherical micelles above critical micelle concentration (CMC). The micellar region extends up to 32 wt %, and an ordering of spherical micelles into micellar cubic phase, I(1), takes place at 33 wt % at 25 °C. The phase transition, I(1) - hexagonal liquid crystal, (H(1)) - lamellar liquid crystal, (L(α)) has been observed with further increase in concentration; moreover, mixed phases are also observed between the pure liquid crystal domains. Similar phases were observed with 16-GLG-16 above 50 °C (Krafft temperature). The partial ternary phase behavior shows that the micellar solutions of m-GLG-m can solubilize a large amount of cationic amphiphile, alkyltrimethylammonium bromide, C(n)TAB, (where n = 14 (TTAB) and 16 (CTAB)) at 25 °C. An addition of C(n)TAB to the aqueous solutions of 16-GLG-16 in a dilute region forms a transparent solution of viscoelastic wormlike micelles at very low concentration (0.25 wt %) even at ambient condition. A mixture of oppositely charged amphiphiles, m-GLG-m and C(n)TAB, exhibits synergism as a result the amphiphile layer curvature, becomes less positive, and favors the transition from sphere to rod to transient networks (wormlike micelles). The gemini amphiphile, 16-GLG-16, forms wormlike micelles at relatively low concentrations compared to others reported so far. Viscosity increases by six orders of magnitude compared to that of pure solvent. The hydrophobic chain length of m-GLG-m and coamphiphile affects the rheology; the maximum viscosity achieved with 16-GLG-16/H(2)O/CTAB is higher than that of 14-GLG-14/H(2)O/CTAB, 12-GLG-12/H(2)O/CTAB, and 16-GLG-16/H(2)O/TTAB systems. These temperature-sensitive systems

  15. Construction of amphiphilic segments on polypropylene nonwoven surface and its application in removal of endocrine disrupting compounds (EDCs) from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kai [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Wei, Junfu, E-mail: junfuwei1963@163.com [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Zhou, Xiangyu [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Liu, Nana [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China)

    2015-05-15

    Highlights: • The amphiphilic segments on polypropylene nonwoven surface were constructed successfully. • The adsorption behavior for EDCs of the amphiphilic adsorption materials was systematically studied. • The novel amphiphilic adsorption materials have broad application prospects in EDCs removal from aqueous solution. - Abstract: The amphiphilic segments on polypropylene nonwoven (PP nonwoven) surface were constructed using the ultraviolet (UV) irradiation graft polymerization for the removal of endocrine disrupting compounds (EDCs) with different polarity from aqueous solution. The stearyl acrylate (SA) as hydrophobic functional monomer was introduced onto the surface of PP nonwoven fabric at first stage and then the hydroxyethyl acrylate (HEA) as hydrophilic functional monomer was introduced subsequently. The effect of functional monomer concentration and UV irradiation time on grafting ratio was studied and discussed. The novel amphiphilic structure was designed and constructed based on adsorption capacity for the target micropollutants. The structure and composition of the amphiphilic adsorption materials were characterized by Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle (CA). The adsorption behaviors for EDCs of the amphiphilic adsorption materials were studied and the results indicated that the adsorption capacity and adsorption rate were superior to single SA grafted PP nonwoven (PP-g-SA) and single HEA grafted PP nonwoven (PP-g-HEA). The novel amphiphilic adsorption material was efficient for the removal of EDCs with different polarity and could be utilized as a potential adsorption material for removing EDCs from aqueous solution.

  16. Tipping the Scale from Disorder to Alpha-helix: Folding of Amphiphilic Peptides in the Presence of Macroscopic and Molecular Interfaces

    OpenAIRE

    Cahit Dalgicdir; Christoph Globisch; Christine Peter; Mehmet Sayar

    2015-01-01

    RESEARCH ARTICLE Tipping the Scale from Disorder to Alpha-helix: Folding of Amphiphilic Peptides in the Presence of Macroscopic and Molecular Interfaces Cahit Dalgicdir1, Christoph Globisch2, Christine Peter2*, Mehmet Sayar1* 1 College of Engineering, Koç University, Istanbul, Turkey, 2 Theoretical Chemistry, University of Konstanz, Konstanz, Germany * (CP); (MS) Abstract Secondary amphiphilicity is inherent to the...

  17. 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

  18. Micro- and nanophase separations in hierarchical self-assembly of strongly amphiphilic block copolymer-based ionic supramolecules

    DEFF Research Database (Denmark)

    Ayoubi, Mehran Asad; Zhu, Kaizheng; Nyström, Bo;

    2013-01-01

    block), a class of ionic supramolecules are successfully synthesized whose molecular architecture consists of a poly(styrene) PS block (Linear block) covalently connected to a strongly amphiphilic comb-like block (AmphComb block), i.e. Linear-b-AmphComb. In the melt state, these ionic supramolecules can......By a selective complexation between different alkyltrimethylammonium amphiphiles (C8, C12 and C16) and three different diblock copolymer systems of poly(styrene)-b-poly(methacrylic acid) at various grafting densities X (X = number of alkyl chains per acidic group of the poly(methacrylic acid) PMAA...... supramolecules, based on complexation between a homopolymer of PMAA and the various alkyltrimethylammonium amphiphiles, were prepared, which nanophase separated into S (C8) or C (C12 and C16) domains....

  19. 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.

  20. Synthesis of Thermoresponsive Amphiphilic Polyurethane Gel as a New Cell Printing Material near Body Temperature.

    Science.gov (United States)

    Tsai, Yi-Chun; Li, Suming; Hu, Shiaw-Guang; Chang, Wen-Chi; Jeng, U-Ser; Hsu, Shan-hui

    2015-12-23

    Waterborne polyurethane (PU) based on poly(ε-caprolactone) (PCL) diol and a second oligodiol containing amphiphilic blocks was synthesized in this study. The microstructure was characterized by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and rheological measurement of the PU dispersion. The surface hydrophilicity measurement, infrared spectroscopy, wide-angle X-ray diffraction, mechanical and thermal analyses were conducted in solid state. It was observed that the presence of a small amount of amphiphilic blocks in the soft segment resulted in significant changes in microstructure. When 90 mol % PCL diol and 10 mol % amphiphilic blocks of poly(l-lactide)-poly(ethylene oxide) (PLLA-PEO) diol were used as the soft segment, the synthesized PU had a water contact angle of ∼24° and degree of crystallinity of ∼14%. The dispersion had a low viscosity below room temperature. As the temperature was raised to body temperature (37 °C), the dispersion rapidly (∼170 s) underwent sol-gel transition with excellent gel modulus (G' ≈ 6.5 kPa) in 20 min. PU dispersions with a solid content of 25-30% could be easily mixed with cells in sol state, extruded by a 3D printer, and deposited layer by layer as a gel. Cells remained alive and proliferating in the printed hydrogel scaffold. We expect that the development of novel thermoresponsive PU system can be used as smart injectable hydrogel and applied as a new type of bio-3D printing ink.

  1. Structural transformation of peptide amphiphile self-assembly induced by headgroup charge and size regulation

    Science.gov (United States)

    Gao, Changrui; Bedzyk, Michael; Olvera, Monica; Kewalramani, Sumit; Palmer, Liam

    The ability to control the nano and the meso-scale architecture of molecular assemblies is one of the major challenges in nanoscience. Significantly, structural transformations of amphiphilic aggregates induced by variations in environmental conditions have attracted attention due to their biotechnological relevance. Here, we study the assembly in aqueous solution for a modular series of peptide amphiphiles with 3, 2 or 1 lysine groups conjugated to a C16 carbon tail (C16K3, C16K2 and C16K1) . This system design allow us to probe how the equilibrium structure of the self-assembly can be tuned by controlling the coupling between steric (via choice of headgroup: K3, K2, or K1) and electrostatic (via solution pH) interactions. Solution small- and wide-angle X-ray scattering (SAXS/WAXS) and transmission electron microscopy (TEM) studies reveal that depending on pH and number of lysines in the lipid headgroup, amphiphiles can assemble into a range of structures: spherical micelles, bilayer ribbons and vesicles. We also perform detailed phase space mapping of pH-and headgroup size dependency of the structures of assembly over 0.1-100 nm length scales via SAXS/WAXS. The experimental results in conjunction with molecular dynamics (MD) simulations deduce quantitative relations between pH-dependent molecular charges, steric constraints and self-assembly morphologies, which is significant for developing experimental routes to obtain assembly structures with specific nano- and meso-scale features through controlled external stimuli.

  2. Nonionic amphiphile nanoarchitectonics: self-assembly into micelles and lyotropic liquid crystals

    Science.gov (United States)

    Shrestha, Lok Kumar; Strzelczyk, Karolina Maria; Goswami Shrestha, Rekha; Ichikawa, Kotoko; Aramaki, Kenji; Hill, Jonathan P.; Ariga, Katsuhiko

    2015-05-01

    Amphiphiles, molecules that possess both hydrophilic and hydrophobic moieties, are architecturally simple molecules that can spontaneously self-assemble into complex hierarchical structures from lower to higher dimensions either in the bulk phase or at an interface. Recent developments in multifunctional nanostructure design using the advanced concept of nanoarchitectonics utilize this simple process of assembly. Amphiphilic self-assemblies involving lipids or proteins mimic the structure of biological systems, thus highlighting the necessity of a fundamental physical understanding of amphiphilic self-assembly towards a realization of the complex mechanisms operating in nature. Herein, we describe self-assembled microstructures of biocompatible and biodegradable tetraglycerol lauryl ether (C12G4) nonionic surfactant in an aqueous solvent system. Temperature-composition analyses of equilibrium phases identified by using small-angle x-ray scattering (SAXS) provide strong evidence of various spontaneously self-assembled mesostructures, such as normal micelles (Wm), hexagonal liquid crystal (H1), and reverse micelles (Om). In contrast to conventional poly(oxyethylene) nonionic surfactants, C12G4 did not exhibit the clouding phenomenon at higher temperatures (phase separation was not observed up to 100 °C), demonstrating the greater thermal stability of the self-assembled mesophases. Generalized indirect Fourier transformation (GIFT) evaluation of the SAXS data confirmed the formation of core-shell-type spherical micelles with a maximum dimension ca. 8.7 nm. The shape and size of the C12G4 micelles remained apparently unchanged over a wide range of concentrations (up to 20%), but intermicellar interactions increased and could be described by the Percus-Yevick (PY) theory (after Carnahan and Starling), which provides a very accurate analytical expression for the osmotic pressure of a monodisperse hard sphere.

  3. Self-assembling Behavior of Amphiphilic Copolymer Containing Cross-linked Hydrophilic Block in Ethanol

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The self-assembly behavior of the amphiphilic block copolymer poly( methyl methacrylate)-block-poly( lead dimethacrylate) (PMMA-b-PLDMA) with cross-linked hydrophilic block (PLDMA) in ethanol was investigated. The results show that the size and morphology of the resulting micelle or micellar aggregates are ascribed to the content of ethanol and the nature of the solvent mixture. PbS nanoparticles were formed in the micelle by in situ reaction with H2S gas. The morphology and size of the self-assembly objects were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  4. Mobilization and biodegradation of 2-methylnaphthalene by amphiphilic polyurethane nano-particle.

    Science.gov (United States)

    Kim, Young-Bum; Kim, Ju-Young; Kim, Eun-ki

    2009-10-01

    Amphiphilic polyurethane (APU) nano-particle enhanced the mobilization of 2-methylnaphthalene (2-MNPT) in soil. Significant increase in the solubility of 2-MNPT was achieved. The molar solubilization ratio was 0.4 (mole 2-MNPT/mole APU). Simple precipitation of APU particle by 2 N CaCl(2) recovered 95% of APU particle and 92% of 2-MNPT simultaneously. Also, 2-MNPT, which was entrapped inside the APU particle, was directly degraded by Acinetobacter sp. as same efficiency as without APU particle. These results showed the potentials of APU particle in the mobilization and biodegradation of hydrophobic compounds from soil. PMID:19214790

  5. Lattice-Gas Simulations of Ternary Amphiphilic Fluid Flow in Porous Media

    CERN Document Server

    Coveney, P V; Wilson, J L; Fowler, P W; Al-Mushadani, O; Boghosian, B M

    1998-01-01

    We develop our existing two-dimensional lattice-gas model to simulate the flow of single-phase, binary-immiscible and ternary-amphiphilic fluids. This involves the inclusion of fixed obstacles on the lattice, together with the inclusion of ``no-slip'' boundary conditions. Here we report on preliminary applications of this model to the flow of such fluids within model porous media. We also construct fluid invasion boundary conditions, and the effects of invading aqueous solutions of surfactant on oil-saturated rock during imbibition and drainage are described.

  6. 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

  7. 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

  8. Control of structure and growth of polymorphic crystalline thin films of amphiphilic molecules on liquid surfaces

    DEFF Research Database (Denmark)

    Weinbach, S.P.; Kjær, K.; Bouwman, W.G.;

    1994-01-01

    The spontaneous formation and coexistence of crystalline polymorphic trilayer domains in amphiphilic films at air-liquid interfaces is demonstrated by grazing incidence synchrotron x-ray diffraction. These polymorphic crystallites may serve as models for the early stages of crystal nucleation and...... growth, helping to elucidate the manner in which additives influence the progress of crystal nucleation, growth, and polymorphism and suggesting ways of selectively generating and controlling multilayers on liquid surfaces. Auxiliary molecules have been designed to selectively inhibit development of the...

  9. Water-repellent textile via decorating fibers with amphiphilic Janus particles.

    Science.gov (United States)

    Synytska, Alla; Khanum, Rina; Ionov, Leonid; Cherif, Chokri; Bellmann, C

    2011-04-01

    We investigated morphology and wetting properties of textiles modified by chemically immobilized amphiphilic micrometer and submicrometer large Janus particles. The Janus particles bind by their reactive side to the textile surface, while their hydrophobic side faces the environment. It was found that the character of immobilization of the Janus particles on textile depends on their size: larger particles bind between fibers, while smaller ones bind to the fiber surface. In both cases, immobilization of Janus particles results in the hydrophobization of the hydrophilic textile surface. Finally, we demonstrated that submicrometer large Janus particles are very efficient for the design of water-repellent textiles. PMID:21366338

  10. Novel self-associative and multiphase nanostructured soft carriers based on amphiphilic hyaluronic acid derivatives

    DEFF Research Database (Denmark)

    Eenschooten, Corinne; Vaccaro, Andrea; Delie, Florence;

    2012-01-01

    The purpose of the present study was to investigate the physicochemical properties in aqueous media of amphiphilic hyaluronic acid (HA) derivatives obtained by reaction of HA’s hydroxyl groups with octenyl succinic anhydride (OSA). The self-associative properties of the resulting octenyl succinic...... anhydridemodified hyaluronic acid (OSA-HA) derivatives were studied by fluorescence spectroscopy using Nile Red as fluorophore. The morphology, size and surface charge of the OSA-HA assemblies were determined by transmission electron microscopy, dynamic light scattering and by measuring their electrophoretic...

  11. Synthesis, Characterization, Critical Micelle Concentration and Biological Activity of two-Headed Amphiphiles

    OpenAIRE

    Actis, Marcelo

    2008-01-01

    In this project, we synthesized a new homologous series of five long-chain, two-headed amphiphiles [2CAm13, 2CAm15, 2CAm17, 2CAm19, 2CAm21; CH3(CH2)n-1CONHC(CH3)(CH2CH2COOH)2, n = 13, 15, 17, 19, 21]. The synthesis of the 2CAmn series was accomplished in four steps. The first step involves a reaction of nitroethane and two equivalents of tert-butyl acrylate to create the nitrodiester synthon [O2NC(CH3)(CH2CH2COOtBu)2] by successive Michael additions. The second step in the synthesi...

  12. Amphiphilic copolymer coated upconversion nanoparticles for near-infrared light-triggered dual anticancer treatment

    Science.gov (United States)

    Yang, Shun; Li, Najun; Liu, Zhuang; Sha, Wenwei; Chen, Dongyun; Xu, Qingfeng; Lu, Jianmei

    2014-11-01

    The light-triggered controlled release of anticancer drugs accompanied with NIR-responsive photodynamic therapy was prepared via a self-assembly process. Firstly, Mn2+-doped upconversion nanoparticles (UCNPs) were coated with a mesoporous silica shell and modified with photosensitizer (Chlorin e6) and long alkyl chains. And then the NIR light-responsive amphiphilic copolymer containing 9,10-dialkoxyanthracene groups was synthesized and then coated as the outermost layer. Upon irradiation with a 980 nm laser, the CCUCNPs@PM would absorb and then convert the NIR light to higher-energy visible red light (660 nm) via the UCNPs-based core, which could excite Chlorin e6 (Ce-6) to produce singlet oxygen (1O2). Then the 1O2-sensitive dialkoxyanthracene group in the amphiphilic copolymer would be degraded and detach from the surface of the CCUCNPs@PM, followed by the controlled release of the pre-loaded drugs and the photodynamic therapy for cancer cells caused by the excess 1O2. In vitro and in vivo experiments also demonstrated that the drug-loaded CCUCNPs@PM possessed better therapeutic efficacy compared with vacant ones. Therefore, the NIR light-controlled chemotherapy and photodynamic therapy could be realized simultaneously by CCUCNPs@PM.The light-triggered controlled release of anticancer drugs accompanied with NIR-responsive photodynamic therapy was prepared via a self-assembly process. Firstly, Mn2+-doped upconversion nanoparticles (UCNPs) were coated with a mesoporous silica shell and modified with photosensitizer (Chlorin e6) and long alkyl chains. And then the NIR light-responsive amphiphilic copolymer containing 9,10-dialkoxyanthracene groups was synthesized and then coated as the outermost layer. Upon irradiation with a 980 nm laser, the CCUCNPs@PM would absorb and then convert the NIR light to higher-energy visible red light (660 nm) via the UCNPs-based core, which could excite Chlorin e6 (Ce-6) to produce singlet oxygen (1O2). Then the 1O2-sensitive

  13. Mobilization and biodegradation of 2-methylnaphthalene by amphiphilic polyurethane nano-particle.

    Science.gov (United States)

    Kim, Young-Bum; Kim, Ju-Young; Kim, Eun-ki

    2009-10-01

    Amphiphilic polyurethane (APU) nano-particle enhanced the mobilization of 2-methylnaphthalene (2-MNPT) in soil. Significant increase in the solubility of 2-MNPT was achieved. The molar solubilization ratio was 0.4 (mole 2-MNPT/mole APU). Simple precipitation of APU particle by 2 N CaCl(2) recovered 95% of APU particle and 92% of 2-MNPT simultaneously. Also, 2-MNPT, which was entrapped inside the APU particle, was directly degraded by Acinetobacter sp. as same efficiency as without APU particle. These results showed the potentials of APU particle in the mobilization and biodegradation of hydrophobic compounds from soil.

  14. Probing the interaction of ferrocene containing hyperbranched poly-ester with model plasma protein: Effect on the interaction mechanism and conformational change

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Fengjuan, E-mail: xfj66@126.com; Gu, Muqing; Liang, Ye; Li, Lanlan; Yu, Xiaolei; Wu, Xiangfeng

    2014-05-01

    Interaction mechanism and conformational change of model plasma protein-bovine serum albumin (BSA) induced by ferrocenyl-functionalized hyperbranched polyester (HBPE-Fc) were investigated using cyclicvoltammetry (CV), differential pulsed voltammetry (DPV), fluorescence, UV–vis absorption spectrometry and circular dichroism (CD). Some complicated interactions occurred between BSA and HBPE-Fc and the new redox centers appeared in the BSA/HBPE-Fc complex that changed and hindered the electron transfer of Fe/Fe{sup 2+}. Fluorescence quenching data showed that the fluorescence of BSA was statically quenched by HBPE-Fc, which implied that ground state complex formed between BSA and HBPE-Fc. van der Waals force and hydrogen bond played major roles in the interaction of HBPE-Fc with BSA. The binding constant Ka for HBPE-Fc–protein interaction is in the order of 10{sup 6} at room temperature indicates that there is a strong interaction between HBPE-Fc and BSA. Synchronous, three-dimensional fluorescence and CD studies indicated that the interaction of BSA with HBPE-Fc induced conformational changes in BSA with overall decrease in the α-helical structure and increase in β-pleated sheet structure. The molecular model of the interaction between HBPE-Fc and BSA was also presented according to the results in this study. - Highlights: • A novel ferrocenyl-functionalized hyperbranched polymer (HBPE-Fc) with potential anticancer effects. • New redox centers appear in the BSA/HBPE-Fc complex that changed and hindered the electron transfer of Fe/Fe{sup 2+}. • BSA fluorescence was statically quenched by HBPE-Fc. • BSA/HBPE-Fc ground state complex was mainly formed by the hydrogen bonds and van der Waals force. • HBPE-Fc induced conformational changes in BSA with overall decrease in the α-helical structure and increase in β-pleated sheet structure. • The molecular model of the interaction was presented according to the results in this study.

  15. NMR investigations of the conformation of new cyclodextrin-based amphiphilic transporters for hydrophobic drugs: molecular lollipops

    Science.gov (United States)

    Bellanger, Nathalie; Perly, Bruno

    1992-10-01

    Amphiphilic compounds, obtained by grafting aliphatic acids onto a modified cyclodextrin, have been synthesized and studied by solution NMR. The large chain-length dependence of the NMR spectra in aqueous media is explained by the possible formation of auto-inclusion complexes. This process has been evidenced by extensive NMR experiments and by competition with potential guests. This new class of molecules ("lollipops") provides important information for the optimization of a design for amphiphilic transporters to be included in organized phases such as micelles or liposomes.

  16. A designed amphiphilic peptide containing the silk fibroin motif as a potential carrier of hydrophobic drugs

    Institute of Scientific and Technical Information of China (English)

    Qinghan Zhou; Juan Lin; Jing Wang; Feng Li; Fushan Tang; Xiaojun Zhao

    2009-01-01

    The amphiphilic peptide is becoming attractive as a potential drug carder to improve the dissolvability of hydrophobic drugs in an aqueous system; thus, facilitating drug uptake by target cells. Here, we report a novel designed amphiphilic peptide, Ac-RADAGAGA-RADAGAGA-NH_2, which was able to stabilize pyrene, a hydrophobic model drug we chose to study in aqueous solution. This designed peptide formed a colloidal suspension by encapsulating pyrene inside the peptide-pyrene complex. Egg phosphatidylcholine (EPC) ves-icles were used to mimic cell bilayer membranes. We found that pyrene was released from the peptide coating into the EPC vesicles by mixing the colloidal suspension with EPC vesicles, which was followed by steady fluorescence spectra as a function of time. A calibration curve for the amount of pyrene released into the EPC vesicles at a given time was used to determine the final concentration of pyrene released into the lipid vesicles from the peptide-pyrene complex. The release rate of the peptide pyrene complex was calculated to quan-tify the transfer of pyrene into EPC vesicles.

  17. 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

  18. Progress in developing amphiphilic cyclodextrin-based nanodevices for drug delivery.

    Science.gov (United States)

    Yaméogo, Josias B G; Géze, Annabelle; Choisnard, Luc; Putaux, Jean-Luc; Semdé, Rasmané; Wouessidjewe, Denis

    2014-01-01

    Nowadays, colloidal drug carriers represent an alternative to solve drug bioavailabily problems. During the past two decades, colloidal drug carriers have proved to improve the therapeutic index of drugs and thus increase their efficacy and/or reduce their toxicity. However, the major challenge in the development of these drug carriers remains the search for materials able to self-organize into stable nanoscale systems. In particular, amphiphilic α-, β- and γ-cyclodextrins (CDs), grafted on their secondary or primary side with different aliphatic chains, have been investigated as drug delivery vehicles due to their ability to self-assemble and form various stable colloidal systems such as micellar aggregates, nanoreservoirs or nanoparticles exhibiting a matricial, multilamellar or hexagonal supramolecular organization. These self-assembled CD-based nanodevices show some advantages in terms of stability, good ability to associate lipophilic drugs and good in vivo tolerance. This review focuses on the potential of the structured nanoparticles obtained from nonionic amphiphilic CDs in drug delivery and targeting. We discuss the synthesis and characterization of the building blocks as well as the preparation and characterization of colloidal particles made from these materials. We also considered some pharmaceutical applications and identified opportunities for an optimum use of this CD-based nanotechnology approach in addressing worldwide priority health problems. PMID:24354667

  19. Biodegradable amphiphilic block copolymers containing functionalized PEO blocks:Controlled synthesis and biomedical potentials

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of controllable amphiphilic block copolymers composed of poly(ethylene oxide)(PEO) as the hydrophilic block and poly(ε-caprolactone)(PCL) as the hydrophobic block with the amino terminal group at the end of the PEO chain(PCL-b-PEO-NH2) were synthesized.Based on the further reaction of reactive amino groups,diblock copolymers with functional carboxyl groups(PCL-b-PEO-COOH) and functional compounds RGD(PCL-b-PEO-RGD) as well as the triblock copolymers with thermosensitive PNIPAAm blocks(PCL-b-PEO-b-PNIPAAM) were synthesized.The well-controlled structures of these copolymers with functional groups and blocks were characterized by gel permeation chromatography(GPC) and 1H NMR spectroscopy.These copolymers with functionalized hydrophilic blocks were fabricated into microspheres for the examination of biofunctions via cell culture experiments and in vitro drug release.The results indicated the significance of introducing functional groups(e.g.,NH2,COOH and RGD) into the end of the hydrophilic block of amphiphilic block copolymers for biomedical potentials in tissue engineering and controlled drug release.

  20. Preparation of pH-responsive membranes with amphiphilic copolymers by surface segregation method☆

    Institute of Scientific and Technical Information of China (English)

    Yanlei Su; Yuan Liu; Xueting Zhao; Yafei Li; Zhongyi Jiang

    2015-01-01

    Novel pH-responsive membranes were prepared by blending pH-responsive amphiphilic copolymers with pol-yethersulfone (PES) via a nonsolvent-induced phase separation (NIPS) technique. The amphiphilic copolymers bearing Pluronic F127 and poly(methacrylic acid) (PMAA) segments, abbreviated as PMAAn–F127–PMAAn, were synthesized by free radical polymerization. The physical and chemical properties of the blend membranes were evaluated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrum, water con-tact angle, Zeta potential and X-ray photoelectron spectroscopy (XPS). The enrichment of hydrophilic PMAA seg-ments on the membrane surfaces was attributed to surface segregation during the membrane preparation process. The blend membranes had significant pH-responsive properties due to the conformational changes of surface-segregated PMAA segments under different pH values of feed solutions. Fluxes of the blend membranes were larger at low pH values of feed solutions than that at high pH values. The pH-responsive ability of the mem-branes was enhanced with the increase of the degree of PMAA near-surface coverage.

  1. Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene

    Directory of Open Access Journals (Sweden)

    Ludmilla Lumholdt

    2014-11-01

    Full Text Available Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixture containing multiple pollutants. The volatile organic compounds are known to form stable inclusion complexes with cyclodextrins. Six different amphiphilic cyclodextrin derivatives were synthesised in order to elucidate whether or not the uptake abilities of the coating depend on the structure of the derivative. Headspace gas chromatography was used for quantification of the uptake exploiting the volatile nature of benzene and its derivatives. The capacity was shown to increase beyond the expected stoichiometries of guest–host complexes with ratios of up to 16:1.

  2. 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

  3. The non-peptidic part determines the internalization mechanism and intracellular trafficking of peptide amphiphiles.

    Directory of Open Access Journals (Sweden)

    Dimitris Missirlis

    Full Text Available BACKGROUND: Peptide amphiphiles (PAs are a class of amphiphilic molecules able to self-assemble into nanomaterials that have shown efficient in vivo targeted delivery. Understanding the interactions of PAs with cells and the mechanisms of their internalization and intracellular trafficking is critical in their further development for therapeutic delivery applications. METHODOLOGY/PRINCIPAL FINDINGS: PAs of a novel, cell- and tissue-penetrating peptide were synthesized possessing two different lipophilic tail architectures and their interactions with prostate cancer cells were studied in vitro. Cell uptake of peptides was greatly enhanced post-modification. Internalization occurred via lipid-raft mediated endocytosis and was common for the two analogs studied. On the contrary, we identified the non-peptidic part as the determining factor of differences between intracellular trafficking and retention of PAs. PAs composed of di-stearyl lipid tails linked through poly(ethylene glycol to the peptide exhibited higher exocytosis rates and employed different recycling pathways compared to ones consisting of di-palmitic-coupled peptides. As a result, cell association of the former PAs decreased with time. CONCLUSIONS/SIGNIFICANCE: Control over peptide intracellular localization and retention is possible by appropriate modification with synthetic hydrophobic tails. We propose this as a strategy to design improved peptide-based delivery systems.

  4. Synthesis of an amphiphilic rhodamine derivative and characterization of its solution and thin film properties

    Energy Technology Data Exchange (ETDEWEB)

    Aviv, Hagit [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel); Harazi, Sivan [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Department of Physics, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel); Schiff, Dillon [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel); Ramon, Yoni [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Department of Physics, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel); Tischler, Yaakov R., E-mail: yrt@biu.ac.il [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel)

    2014-08-01

    Here we present characterization of solution and thin film properties of Lissamine rhodamine B sulfonyl didodecyl amine (LRSD), an amphiphilic derivative of rhodamine. LRSD was synthesized by functionalizing Lissamine rhodamine B sulfonyl chloride (LRSC) with didodecylamine via a straightforward sulfonylation reaction. LRSD's long alkane chains make it highly soluble in chloroform, with a marked increase in brightness compared to the starting material. LRSD is shown to form well-defined robust micelles in water, without the addition of a co-surfactant and stable monolayers at the air–water interface. The greater lipophilicity of LRSD also enables doping into non-polar polymeric host matrices such as polystyrene with less aggregation and hence higher fluorescence quantum yield than LRSC or even rhodamine B. The monolayers of LRSD were prepared via Langmuir–Blodgett deposition and showed shifts in the photoluminescence peak from 575 nm to 595 nm, as the surface pressure is varied from 3 mN/m to 11 mN/m. - Highlights: • Lissamine rhodamine B sulfonyl didodecyl amine (LRSD) is soluble in chloroform. • LRSD shows robust quantum yield in solution and as a dopant in thin film. • LRSD is an amphiphilic rhodamine dye that forms compact fluorescent micelles. • LRSD forms a stable isotherm when spread at the air–water interface.

  5. Amphiphilic Beads as Depots for Sustained Drug Release Integrated into Fibrillar Scaffolds

    Science.gov (United States)

    Gaharwar, Akhilesh K.; Mihaila, Silvia M.; Kulkarni, Ashish A.; Patel, Alpesh; Di Luca, Andrea; Reis, Rui L.; Gomes, Manuela E.; van Blitterswijk, Clemens; Moroni, Lorenzo; Khademhosseini, Ali

    2014-01-01

    Native extracellular matrix (ECM) is a complex fibrous structure loaded with bioactive cues that affects the surrounding cells. A promising strategy to mimicking native tissue architecture for tissue engineering applications is to engineer fibrous scaffolds using electrospinning. By loading appropriate bioactive cues within these fibrous scaffolds, various cellular functions such as cell adhesion, proliferation and differentiation can be regulated. Here, we report on the encapsulation and sustained release of model hydrophobic drug (dexamethasone (Dex)) within beaded fibrillar scaffold of poly(ethylene oxide terephthalate)-poly(butylene terephthalate) (PEOT/PBT), a polyether-ester multiblock copolymer to direct differentiation of human mesenchymal stem cells (hMSCs). The amphiphilic beads act as depots for sustained drug release that is integrated into the fibrillar scaffolds. The entrapment of Dex within the beaded structure results in sustained release of drug over the period of 28 days. This is mainly attributed to the diffusion driven release of Dex from the amphiphilic electrospun scaffolds. In vitro results indicate that hMSCs cultured on Dex containing beaded fibrillar scaffolds exhibit an increase in osteogenic differentiation potential, as evidenced by increased alkaline phosphatase (ALP) activity, compared to the direct infusion of Dex in culture medium. The formation of mineralized matrix is also significantly enhanced due to the controlled Dex release from the fibrous scaffolds. This approach can be used to engineer scaffolds with appropriate chemical cues to direct tissue regeneration. PMID:24794894

  6. Preparation and Microbiological Evaluation of Amphiphilic Kanamycin-Lipoamino Acid Ion-Pairs

    Directory of Open Access Journals (Sweden)

    Rosario Pignatello

    2014-05-01

    Full Text Available Amphiphilic ion-pairs of kanamycin (KAN were prepared by evaporation of a water-ethanol co-solution of KAN base and a lipoamino acid bearing a 12-carbon atoms alkyl side chain (LAA12, at different molar ratios. Infrared spectroscopy confirmed the structure of ion-pairs, while differential scanning calorimetry (DSC and powder X-ray diffractometry (PXRD studies supported the formation of new saline species with a different crystalline structure than the starting components. The solubility pattern shown in a range of both aqueous and organic solvents confirmed that the ion-pairs possess an amphiphilic character. The LAA12 counter-ion showed not to improve the antibacterial activity of KAN, suggesting that such chemical strategy is not able to favor the penetration of this drug inside the bacteria cells. Nevertheless, a slight improving, i.e., a one-fold dilution, was observed in E. coli. The present study can also serve as the basis for a further evaluation of LAA ion-pairing of antibiotics, as a means to improve the loading of hydrophilic drugs into lipid-based nanocarriers.

  7. 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

  8. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    International Nuclear Information System (INIS)

    Fullerene C60 sub-colloidal particle with diameter ∼1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C60 fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent molecules—water retardation—in the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the “dangling” –OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some “dry” regions of C60 are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique

  9. Using amphiphilic nanostructures to enable long-range ensemble coalescence and surface rejuvenation in dropwise condensation.

    Science.gov (United States)

    Anderson, David M; Gupta, Maneesh K; Voevodin, Andrey A; Hunter, Chad N; Putnam, Shawn A; Tsukruk, Vladimir V; Fedorov, Andrei G

    2012-04-24

    Controlling coalescence events in a heterogeneous ensemble of condensing droplets on a surface is an outstanding fundamental challenge in surface and interfacial sciences, with a broad practical importance in applications ranging from thermal management of high-performance electronic devices to moisture management in high-humidity environments. Nature-inspired superhydrophobic surfaces have been actively explored to enhance heat and mass transfer rates by achieving favorable dynamics during dropwise condensation; however, the effectiveness of such chemically homogeneous surfaces has been limited because condensing droplets tend to form as pinned Wenzel drops rather than mobile Cassie ones. Here, we introduce an amphiphilic nanostructured surface, consisting of a hydrophilic base with hydrophobic tips, which promotes the periodic regeneration of nucleation sites for small droplets, thus rendering the surface self-rejuvenating. This unique amphiphilic nanointerface generates an arrangement of condensed Wenzel droplets that are fluidically linked by a wetted sublayer, promoting previously unobserved coalescence events where numerous droplets simultaneously merge, without direct contact. Such ensemble coalescences rapidly create fresh nucleation sites, thereby shifting the overall population toward smaller droplets and enhancing the rates of mass and heat transfer during condensation.

  10. 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.

  11. Oligonucleotide delivery with cell surface binding and cell penetrating Peptide amphiphile nanospheres.

    Science.gov (United States)

    Mumcuoglu, Didem; Sardan, Melis; Tekinay, Turgay; Guler, Mustafa O; Tekinay, Ayse B

    2015-05-01

    A drug delivery system designed specifically for oligonucleotide therapeutics can ameliorate the problems associated with the in vivo delivery of these molecules. The internalization of free oligonucleotides is challenging, and cytotoxicity is the main obstacle for current transfection vehicles. To develop nontoxic delivery vehicles for efficient transfection of oligonucleotides, we designed a self-assembling peptide amphiphile (PA) nanosphere delivery system decorated with cell penetrating peptides (CPPs) containing multiple arginine residues (R4 and R8), and a cell surface binding peptide (KRSR), and report the efficiency of this system in delivering G-3129, a Bcl-2 antisense oligonucleotide (AON). PA/AON (peptide amphiphile/antisense oligonucleotide) complexes were characterized with regards to their size and secondary structure, and their cellular internalization efficiencies were evaluated. The effect of the number of arginine residues on the cellular internalization was investigated by both flow cytometry and confocal imaging, and the results revealed that uptake efficiency improved as the number of arginines in the sequence increased. The combined effect of cell penetration and surface binding property on the cellular internalization and its uptake mechanism was also evaluated by mixing R8-PA and KRSR-PA. R8 and R8/KRSR decorated PAs were found to drastically increase the internalization of AONs compared to nonbioactive PA control. Overall, the KRSR-decorated self-assembled PA nanospheres were demonstrated to be noncytotoxic delivery vectors with high transfection rates and may serve as a promising delivery system for AONs. PMID:25828697

  12. Rapidly recovering hydrogel scaffolds from self-assembling diblock copolypeptide amphiphiles

    Science.gov (United States)

    Nowak, Andrew P.; Breedveld, Victor; Pakstis, Lisa; Ozbas, Bulent; Pine, David J.; Pochan, Darrin; Deming, Timothy J.

    2002-05-01

    Protein-based hydrogels are used for many applications, ranging from food and cosmetic thickeners to support matrices for drug delivery and tissue replacement. These materials are usually prepared using proteins extracted from natural sources, which can give rise to inconsistent properties unsuitable for medical applications. Recent developments have utilized recombinant DNA methods to prepare artificial protein hydrogels with specific association mechanisms and responsiveness to various stimuli. Here we synthesize diblock copolypeptide amphiphiles containing charged and hydrophobic segments. Dilute solutions of these copolypeptides would be expected to form micelles; instead, they form hydrogels that retain their mechanical strength up to temperatures of about 90°C and recover rapidly after stress. The use of synthetic materials permits adjustment of copolymer chain length and composition, which we varied to study their effect on hydrogel formation and properties. We find that gelation depends not only on the amphiphilic nature of the polypeptides, but also on chain conformations-α-helix, β-strand or random coil. Indeed, shape-specific supramolecular assembly is integral to the gelation process, and provides a new class of peptide-based hydrogels with potential for applications in biotechnology.

  13. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    Energy Technology Data Exchange (ETDEWEB)

    Varanasi, S. R., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de; John, A. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Guskova, O. A., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Sommer, J.-U. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Institut für Theoretische Physik, Technische Universität Dresden, Zellescher Weg 17, Dresden D-01069 (Germany)

    2015-06-14

    Fullerene C{sub 60} sub-colloidal particle with diameter ∼1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C{sub 60} fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent molecules—water retardation—in the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the “dangling” –OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some “dry” regions of C{sub 60} are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique.

  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. 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.

  16. Effect of headgroup-substrate interactions on the thermal behavior of long-chain amphiphiles

    Science.gov (United States)

    Singla, Saranshu; Zhu, He; Dhinojwala, Ali

    The structure of amphiphilic molecules at liquid/solid and solid/solid interfaces is relevant in understanding lubrication, colloid stabilization, chromatography, and nucleation. Here, we characterize the interfacial structures of long chain amphiphilic molecules with different head groups (OH, COOH, NH2) using interface-sensitive sum frequency generation (SFG) spectroscopy. The behavior of these self-assembled monolayers (SAMs) on sapphire substrate is recorded in situ as a function of temperature (above and below bulk Tm) using SFG. Previous studies using synchrotron X-ray reflectivity and SFG show that the melting point of an ordered hexadecanol monolayer is around 30°C above its bulk Tm. The thermal stability of the monolayer is explained due to strong hydrogen bonding interactions between the head-group and the sapphire substrate. The strength of these hydrogen-bonding interactions between substrate and different head groups is calculated using the Badger-Bauer equation. Below Tm, the ordered monolayer influenced the structure of the interfacial crystalline layer, and the transition from monolayer to the bulk crystalline phases. The results with different head groups will be presented.

  17. Design of amphiphilic oligopeptides as models for fine tuning peptide assembly with plasmid DNA.

    Science.gov (United States)

    Goparaju, Geetha N; Gupta, Pardeep K

    2014-08-01

    We discuss the design of novel amphiphilic oligopeptides with hydrophobic and cationic amino acids to serve as models to understand peptide-DNA assembly. Biophysical and thermodynamic characterization of interaction of these amphiphilic peptides with plasmid DNA is presented. Peptides with at least +4 charges favor stable complex formation. Surface potential is dependent on the type of hydrophobic amino acid for a certain charge. Thermodynamically it is a spontaneous interaction between most of the peptides and plasmid DNA. Lys(7) and Tyr peptides with +4/+5 charges indicate cooperative binding with pDNA without saturation of interaction while Val(2)-Gly-Lys(4), Val-Gly-Lys(5), and Phe-Gly-Lys(5) lead to saturation of interaction indicating condensed pDNA within the range of N/Ps studied. We show that the biophysical properties of DNA-peptide complexes could be modulated by design and the peptides presented here could be used as building blocks for creating DNA-peptide complexes for various biomedical applications, mainly nucleic acid delivery.

  18. 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

  19. 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.

  20. First-order phase transition during displacement of amphiphilic biomacromolecules from interfaces by surfactant molecules.

    Science.gov (United States)

    Ettelaie, Rammile; Dickinson, Eric; Pugnaloni, Luis

    2014-11-19

    The adsorption of surfactants onto a hydrophobic interface, already laden with a fixed number of amphiphilic macromolecules, is studied using the self consistent field calculation method of Scheutjens and Fleer. For biopolymers having unfavourable interactions with the surfactant molecules, the adsorption isotherms show an abrupt jump at a certain value of surfactant bulk concentration. Alternatively, the same behaviour is exhibited when the number of amphiphilic chains on the interface is decreased. We show that this sudden jump is associated with a first-order phase transition, by calculating the free energy values for the stable and the metastable states at both sides of the transition point. We also observe that the transition can occur for two approaching surfaces, from a high surfactant coverage phase to a low surfactant coverage one, at sufficiently close separation distances. The consequence of this finding for the steric colloidal interactions, induced by the overlap of two biopolymer + surfactant films, is explored. In particular, a significantly different interaction, in terms of its magnitude and range, is predicted for these two phases. We also consider the relevance of the current study to problems involving the competitive displacement of proteins by surfactants in food colloid systems.