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Sample records for poly allylamine synthesized

  1. Targeted Delivery of Docetaxel by Use of Transferrin/Poly(allylamine hydrochloride)-functionalized Graphene Oxide Nanocarrier.

    PubMed

    Nasrollahi, Fatemeh; Varshosaz, Jaleh; Khodadadi, Abbas Ali; Lim, Sierin; Jahanian-Najafabadi, Ali

    2016-06-01

    The exceptional chemical and physical properties of graphene oxide (GO) make it an attractive nanomaterial for biomedical applications, particularly in drug delivery. In this work we synthesized a novel, GO-based nanocarrier for the delivery of docetaxel (DTX), a potent hydrophobic chemotherapy drug. The GO was functionalized with transferrin (Tf)-poly(allylamine hydrochloride) (PAH), which provided targeted and specific accumulation to extracellular Tf receptors and stabilized GO in physiological solutions. Tf was conjugated to PAH via amide covalent linkages, and Tf-PAH coated the surface of DTX-loaded GO through electrostatic interactions. The morphology and structure of the resulting nanostructure, along with its surface modifications, were verified by use of Fourier transform infrared (FT-IR) and UV-vis spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM). DTX was loaded at a relatively high loading capacity of 37% and released in a pH-dependent and sustained manner under physiological conditions. The targeting efficiency and cytotoxicity of this drug delivery system were evaluated on MCF-7 breast cancer cells. Improved efficacy of targeted DTX-loaded nanocarrier was observed compared to nontargeted carrier and free DTX, especially at high drug concentrations. The Tf-PAH-functionalized GO nanocarrier is a promising candidate for targeted delivery and controlled release of DTX. PMID:27158834

  2. Comparative study of layer-by-layer deposition techniques for poly(sodium phosphate) and poly(allylamine hydrochloride)

    PubMed Central

    2013-01-01

    An inorganic short chain polymer, poly(sodium phosphate), PSP, together with poly(allylamine hydrochloride), PAH, is used to fabricate layer-by-layer (LbL) films. The thickness, roughness, contact angle, and optical transmittance of these films are studied depending on three parameters: the precursor solution concentrations (10-3 and 10-4 M), the number of bilayers deposited (20, 40, 60, 80, and 100 bilayers), and the specific technique used for the LbL fabrication (dipping or spraying). In most cases of this experimental study, the roughness of the nanofilms increases with the number of bilayers. This contradicts the basic observations made in standard LbL assemblies where the roughness decreases for thicker coatings. In fact, a wide range of thickness and roughness was achieved by means of adjusting the three parameters mentioned above. For instance, a roughness of 1.23 or 205 nm root mean square was measured for 100 bilayer coatings. Contact angles close to 0 were observed. Moreover, high optical transmittance is also reported, above 90%, for 80 bilayer films fabricated with the 10-4 M solutions. Therefore, these multilayer structures can be used to obtain transparent superhydrophilic surfaces. PMID:24359137

  3. Determination of uric acid level by polyaniline and poly (allylamine): Based biosensor.

    PubMed

    Wathoni, Nasrul; Hasanah, Aliya Nur; Gozali, Dolih; Wahyuni, Yeni; Fauziah, Lia Layusa

    2014-01-01

    The uric acid biosensor has been much developed by immobilizing uricase enzyme into the membrane of conductive polymer and the membrane of polyelectrolyte such as polyaniline (PANI) and poly (allylamine) (PAA) respectively. The purpose of this research was to create a new amperometric uric acid biosensor by immobilization of uricase in combination between PANI and PAA membranes. The working electrode was Pt plate (0.5 mm). The auxiliary and the reference electrode were Pt wire 0.4 mm and Ag/AgCl respectively. Uricase, uric acid, PAA, pyrrole and glutaraldehyde were supplied from Sigma. All other chemical was obtained from Merck. The biosensor was created by immobilizing of uricase by a glutaraldehyde crosslinking procedure on PANI composite film on the surface of a platinum electrode while the polyelectrolyte layer of PAA were prepared via layer-by-layer assembly on the electrode, functioning as H2O2-selective film. Standard of deviation, coefficient of variation (CV) and coefficient of correlation (r) analysis were used in this study. The biosensor had a good linearity with a correlation coefficient of 0.993 and it could be used up to 27 times with the CV value of 3.97%. The presence of other compounds such as glucose and ascorbic acid gave 1.3 ± 1.13% and 3.27 ± 2.29% respectively on the interference effect toward the current response of uric acid biosensor. The polymer combination of PANI and PAA can be used as a selective matrix of uric acid biosensor. PMID:24696812

  4. Enhanced accumulation and visible light-assisted degradation of azo dyes in poly(allylamine hydrochloride)-modified mesoporous silica spheres

    SciTech Connect

    Tao Xia Liu Bing; Hou Qian; Xu Hui; Chen Jianfeng

    2009-02-04

    A new route for the economic and efficient treatment of azo dye pollutants is reported, in which surface-modified organic-inorganic hybrid mesoporous silica (MS) spheres were chosen as microreactors for the accumulation and subsequent photodegradation of pollutants in defined regions. The surface-modified silica materials were prepared by anchoring the polycationic species such as poly(allylamine hydrochloride) on MS spheres via a simple wet impregnation method. The as-synthesized spheres with well-defined porous structures exhibited 15 times of accumulating capacity for orange II and Congo red compared to that of the pure MS spheres. Diffuse reflectance UV-vis spectroscopy and confocal laser scanning microscopy demonstrated that the accumulated orange II and CR in defined MS spheres were rapidly degraded in the presence of Fenton reagent under visible radiation. Kinetics analysis in recycling degradation showed that the as-synthesized materials might be utilized as environment-friendly preconcentrators/microreactors for the remediation of dye wastewater.

  5. Thiophene congeners of morpholine and allylamine type antifungals--syntheses and biological activities.

    PubMed

    Bracher, F; Papke, T

    1995-08-01

    A thiophene analogue 8 of the antifungal drug amorolfine (1) was prepared starting from the alcohol 5. In addition, congeners of naftifine, terbinafine and butenafine, in which the naphthalene ring is replaced by a branched thienylalkyl group, wee synthesized. Of the four drug analogues only compound 9, related to terbinafine, showed significant antifungal activity. PMID:7568314

  6. pH-sensing properties of cascaded long- and short-period fiber grating with poly acrylic acid/poly allylamine hydrochloride thin-film overlays

    NASA Astrophysics Data System (ADS)

    Yang, Ying

    2014-11-01

    Based on coupled-mode theory and transfer matrix method, the mode coupling mechanism and the reflection spectral properties of coated cascaded long- and short-period gratings (CLBG) are discussed. The effects of the thin-film parameters (film refractive index and film thickness) on the reflection spectra of the coated CLBG are simulated. By using electrostatic self-assembly method, poly acrylic acid (PAA) and poly allylamine hydrochloride (PAH) multilayer molecular pH-sensitive thin-films are assembled on the surface of the partial corroded CLBG. When the CLBG coated with PAA/PAH films are used to sense pH values, the resonant wavelengths of the CLBG have almost no shift, whereas the resonance peak reflectivities change with pH values. In addition, the sensitivities of the resonance peak reflectivities responding to pH values are improved by an order of magnitude.

  7. Preparation and characterization of magnetic allylamine modified graphene oxide-poly(vinyl acetate-co-divinylbenzene) nanocomposite for vortex assisted magnetic solid phase extraction of some metal ions.

    PubMed

    Khan, Mansoor; Yilmaz, Erkan; Sevinc, Basak; Sahmetlioglu, Ertugrul; Shah, Jasmin; Jan, Muhammad Rasul; Soylak, Mustafa

    2016-01-01

    Magnetic allylamine modified graphene oxide-poly(vinyl acetate-co-divinylbenzene) (MGO-DVB-VA) was synthesized and used for magnetic solid phase extraction of Pb(II), Cd(II), Cu(II), Ni(II) and Co(II) prior to their determination by flame atomic absorption spectroscopy. The adsorbent surface functional group was characterized by using FT-IR and Raman spectroscopy. XRD pattern was used to determine the layers of GO. Surface morphology and elemental composition of the adsorbent were evaluated by using SEM and EDX analysis. Various parameters, effecting adsorption efficiency like initial solution pH, adsorbent dose, type and volume of eluent, volume of sample and diverse ions effects were optimized. The preconcentration factor (PF) is 40 for all the metals and the limits of detection for Pb, Cd, Cu, Ni and Co are in the range of 0.37-2.39 µg L(-1) and relative standard deviation below 3.1%. The method was validated by using the method for certified reference materials (Tobacco Leaves (INCT-OBTL-5), Tomato Leaves (1573a), Certified Water (SPS-ww2) and Certified Water (TMDA 64-2)). The method was successfully applied for natural water and food samples. PMID:26695244

  8. Impedimetric sensor for toxigenic Penicillium sclerotigenum detection in yam based on magnetite-poly(allylamine hydrochloride) composite.

    PubMed

    Silva, Gilcelia J L; Andrade, Cesar A S; Oliveira, Idjane S; de Melo, Celso P; Oliveira, Maria D L

    2013-04-15

    We describe a new DNA biosensor for the detection of toxigenic Penicillium sclerotigenum in pure culture or infected yams. The P. sclerotigenum detection takes place on a self-assembled monolayer of a (magnetite)/(poly(allylamine hydrochloride)) (Fe3O4-PAH) composite that serves as an anchoring layer for the DNA hybridization interaction. Electrical impedance spectroscopy (EIS) was used to evaluate and quantify the hybridization degree. The Fe3O4-PAH composite is a good platform for the immobilization of biomolecules, due to the presence of many possible binding sites for nucleotides and to its large surface-to-volume ratio and good biocompatibility. The biosensor was capable of not only qualitatively detecting the presence of the fungus genome at low concentrations, but also shown a good quantitative impedimetric response its electrical resistance was monitored along the time of exposure. A Fe3O4-PAH-probe biosensor would require only small volumes and low concentrations of the analyte when used, for instance, in detecting P. sclerotigenum contamination of food, besides presenting many comparative advantages, such as selectivity, specificity and reproducibility, relative to alternative techniques. PMID:23465186

  9. Comparison of the binding mode of plasmid DNA to allylamine plasma polymer and poly(ethylene glycol) surfaces

    NASA Astrophysics Data System (ADS)

    Hook, Andrew L.; Thissen, Helmut; Quinton, Jamie; Voelcker, Nicolas H.

    2008-05-01

    Concomitant with the development of advanced biomaterials and other biodevices, the precise control of biomolecule-surface interactions is becoming increasingly important. Of particular interest are devices presenting functional DNA either for hybridization or for uptake by cells. Such devices are poised to underpin advanced genomic studies and DNA therapy. However, these devices require an in-depth understanding of how specific biomolecules interact with particular surfaces. This report investigates how DNA interacts with two coatings commonly used for the control of protein and cell-surface interactions on biomedical devices, focusing on the nature of the DNA-surface interactions. The coatings were produced by allylamine plasma polymerization (ALAPP) and subsequent high-density grafting of poly(ethylene glycol) (PEG). While the low protein binding nature of such coatings has been shown before, we show here that PEG grafted surfaces also exhibit significantly reduced attachment of double-stranded plasmid DNA with an equilibrium constant of 680 ml/mg as compared with 1600 ml/mg for ALAPP modified surfaces. Given these findings, there is scope to produce two-dimensionally controlled DNA adsorption patterns on spatially patterned ALAPP and PEG chemistries. Significantly, both hydrophobic and electrostatic interactions were shown to contribute to the binding of DNA to the ALAPP film. Finally, the ability to manipulate DNA by applying an electrical bias to these surfaces was also demonstrated.

  10. Electrospun polyamide 6/poly(allylamine hydrochloride) nanofibers functionalized with carbon nanotubes for electrochemical detection of dopamine.

    PubMed

    Mercante, Luiza A; Pavinatto, Adriana; Iwaki, Leonardo E O; Scagion, Vanessa P; Zucolotto, Valtencir; Oliveira, Osvaldo N; Mattoso, Luiz H C; Correa, Daniel S

    2015-03-01

    The use of nanomaterials as an electroactive medium has improved the performance of bio/chemical sensors, particularly when synergy is reached upon combining distinct materials. In this paper, we report on a novel architecture comprising electrospun polyamide 6/poly(allylamine hydrochloride) (PA6/PAH) nanofibers functionalized with multiwalled carbon nanotubes, used to detect the neurotransmitter dopamine (DA). Miscibility of PA6 and PAH was sufficient to form a single phase material, as indicated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), leading to nanofibers with no beads onto which the nanotubes could adsorb strongly. Differential pulse voltammetry was employed with indium tin oxide (ITO) electrodes coated with the functionalized nanofibers for the selective electrochemical detection of dopamine (DA), with no interference from uric acid (UA) and ascorbic acid (AA) that are normally present in biological fluids. The response was linear for a DA concentration range from 1 to 70 μmol L(-1), with detection limit of 0.15 μmol L(-1) (S/N = 3). The concepts behind the novel architecture to modify electrodes can be potentially harnessed in other electrochemical sensors and biosensors. PMID:25644325

  11. Poly(N-isopropylacrylamide-co-allylamine) (PNIPAM-co-ALA) nanospheres for the thermally triggered release of Bacteriophage K.

    PubMed

    Hathaway, Hollie; Alves, Diana R; Bean, Jessica; Esteban, Patricia P; Ouadi, Khadija; Sutton, J Mark; Jenkins, A Toby A

    2015-10-01

    Due to the increased prevalence of resistant bacterial isolates which are no longer susceptible to antibiotic treatment, recent emphasis has been placed on finding alternative modes of treatment of wound infections. Bacteriophage have long been investigated for their antimicrobial properties, yet the utilization of phage therapy for the treatment of wound infections relies on a suitable delivery system. Poly(N-isopropylacrylamide) (PNIPAM) is a thermally responsive polymer which undergoes a temperature dependent phase transition at a critical solution temperature. Bacteriophage K has been successfully formulated with PNIPAM nanospheres copolymerized with allylamine (PNIPAM-co-ALA). By utilizing a temperature responsive polymer it has been possible to engineer the nanospheres to collapse at an elevated temperature associated with a bacterial skin infection. The nanogels were reacted with surface deposited maleic anhydride in order to anchor the nanogels to non-woven fabric. Bacteriophage incorporated PNIPAM-co-ALA nanospheres demonstrated successful bacterial lysis of a clinically relevant bacterial isolate - Staphylococcus aureus ST228 at 37°C, whilst bacterial growth was unaffected at 25°C, thus providing a thermally triggered release of bacteriophage. PMID:26423908

  12. Characterization of charge properties of an ultrafiltration membrane modified by surface grafting of poly(allylamine) hydrochloride.

    PubMed

    Dejeu, J; Lakard, B; Fievet, P; Lakard, S

    2009-05-01

    A polyethersulfone ultrafiltration membrane was functionalized by a cationic polyelectrolyte, the poly(allylamine) hydrochloride (PAH). The influence of the time of adsorption of PAH on the membrane charge properties was studied. Several characterization techniques were used to investigate the membrane modification. Tangential and transmembrane streaming potential measurements were conducted to characterize the outer and inner surfaces of the membrane, respectively. Both techniques indicated that the surface modification of the membrane was efficient. The charge of the outer surface was reversed (from negative values for the unmodified membrane to positive values for the modified membrane) and the charge of the inner surface was neutralized after adsorption of the cationic polyelectrolyte onto the pore walls. The modification of both the outer surface of the membrane and the pore walls was also put in evidence with membrane potential measurements. It was found that the charge of the PAH-modified membrane is affected by the time of immersion in PAH solution. Experimental data seem to show a fast modification of the membrane for the first 15 min; nevertheless, the modification was more pronounced after 24 h of PAH adsorption. Diffusion experiments carried out with unmodified and modified membranes for four salts (KCl, NaCl, MgCl, and CaCl(2)) showed a decrease in the salt permeability after functionalization of the membrane. The permeability decrease was greater for 2:1 salts than for 1:1 salts. This decrease was explained by electrostatic interactions. PMID:19215937

  13. Composite films of poly(allylamine)-capped polydopamine nanoparticles and P8W48 polyoxometalates with electroactive properties.

    PubMed

    Ball, Vincent; Haider, Ali; Kortz, Ulrich

    2016-11-01

    Polyoxometalates (POMs) are often used to functionalize surfaces with photochromic or electroactive compounds. Among the common deposition methods, besides the Langmuir-Blodgett deposition, the layer-by-layer (LBL) deposition method has become more and more popular due to its facility and versatility combined with the polyanionic character of POMs. The LBL deposition of POMs and oppositely charged nanoparticles is however poorly described in the literature. Using polydopamine nanoparticles (PDA) produced in the presence of poly(allylamine) and displaying a hydrodynamic diameter of 25nm, we show that LBL films containing the large, cyclic P8W48 polyanion and the PDA@PAH nanoparticles display reduction currents which are proportional to the number of deposition steps and hence to the film thickness. In addition the obtained films display not only the electrochemical properties of the POM but also that of PDA nanoparticles. Hence we demonstrate the feasibility to build up films based on particles only with the electrochemical behavior of each kind of particles being conserved. PMID:27474813

  14. Formation and Structure of Calcium Carbonate Thin Films and Nanofibers Precipitated in the Presence of Poly(Allylamine Hydrochloride) and Magnesium Ions

    PubMed Central

    2013-01-01

    That the cationic polyelectrolyte poly(allylamine hydrochloride) (PAH) exerts a significant influence on CaCO3 precipitation challenges the idea that only anionic additives have this effect. Here, we show that in common with anionic polyelectrolytes such as poly(aspartic acid), PAH supports the growth of calcite thin films and abundant nanofibers. While investigating the formation of these structures, we also perform the first detailed structural analysis of the nanofibers by transmission electron microscopy (TEM) and selected area electron diffraction. The nanofibers are shown to be principally single crystal, with isolated domains of polycrystallinity, and the single crystal structure is even preserved in regions where the nanofibers dramatically change direction. The formation mechanism of the fibers, which are often hundreds of micrometers long, has been the subject of intense speculation. Our results suggest that they form by aggregation of amorphous particles, which are incorporated into the fibers uniquely at their tips, before crystallizing. Extrusion of polymer during crystallization may inhibit particle addition at the fiber walls and result in local variations in the fiber nanostructure. Finally, we investigate the influence of Mg2+ on CaCO3 precipitation in the presence of PAH, which gives thinner and smoother films, together with fibers with more polycrystalline, granular structures. PMID:24489438

  15. Amperometric Glucose Biosensor Based on Effective Self-Assembly Technology for Preparation of Poly(allylamine hydrochloride)/Au Nanoparticles Multilayers.

    PubMed

    Ye, Yuhang; Xie, Hangqing; Shao, Xiaobao; Wei, Yuan; Liu, Yuhong; Zhao, Wenbo; Xia, Xinyi

    2016-03-01

    Novel nanomaterials and nanotechnology for use in bioassay applications represent a rapidly advancing field. This study developed a novel method to fabricate the glucose biosensor with good gold nanoparticles (AuNPs) fixed efficiency based on effective self-assembly technology for preparation of multilayers composed of poly(allylamine hydrochloride) (PAH) and AuNPs. The electrochemical properties of the biosensor based on (AuNPs/PAH)n/AuNPs/glucose oxide (GOD) with different multilayers were systematically investigated. Among the resulting glucose biosensors, electrochemical properties of the biosensor with three times self-assembly processes ((AuNPs/PAH)3/AuNPs/GOD) is best. The GOD biosensor exhibited a fast amperometric response (5 s) to glucose, a good linear current-time relation over a wide range of glucose concentrations from 0.05 to 162 mM, and a low detection limit of 0.029 mM. The GOD biosensor modified with (AuNPs/PAH)n layers will have essential significance and practical application in future owing to the simple method of fabrication and good performance. PMID:27455628

  16. Exothermic-Endothermic Transition in the Titration of Poly(allylamine chloride) with Sodium Hexametaphoshate Associated with a Change in the Proton Release Regime.

    PubMed

    Maechling, Clarisse; Ball, Vincent

    2016-05-26

    The formation of complexes (aggregates) between oppositely charged macromolecular species or between macromolecular species and multivalent ions is a fascinating fundamental research topic that allows one to understand fundamental processes in biology and in polymer science. In addition interpolyelectrolyte complexes hold by strong interactions and polyelectrolyte coacervates in which the stabilizing interactions are weaker find many applications in food and in colloidal science. The interactions between oppositely charged species are usually investigated as a function of intensive variables like the temperature, the pH, the ionic strength, and parameters related to the charged species themselves (molecular mass, charge density, charge distribution, and so forth). It appeared however in the past few years that the interaction kinetics is also of fundamental importance; a fast mixing of the interacting species can lead to the formation of frozen and out-of-equilibrium structures. The present investigation is aimed to study the interactions between a small polyphosphate (sodium hexametaphosphate) (HMP) and a linear polyamine (poly(allylamine hydrochloride)) (PAH) from both a thermodynamic and kinetic point of view as a function of the ionic strength (in NaCl solutions). It is found, unexpectedly, that the interaction is of biphasic nature with a first exothermic regime followed by an endothermic regime. The transition between both regimes is ionic strength independent between 10 and 2000 mM emphasizing the strong interactions between both species. It occurs at a charge ratio of about 0.4 between the number of negative and positive charges and is correlated with proton release in the exothermic regime and a proton uptake in the endothermic regime. When HMP solutions are titrated in PAH solutions the turbidity of the mixtures is not the same as that obtained during the reverse titration at a given charge ratio, emphasizing the difficulty to establish an "equilibrium

  17. Cellular uptake of poly(allylamine hydrochloride) microcapsules with different deformability and its influence on cell functions.

    PubMed

    Yu, Wei; Zhang, Wenbo; Chen, Ying; Song, Xiaoxue; Tong, Weijun; Mao, Zhengwei; Gao, Changyou

    2016-03-01

    It is important to understand the safety issue and cell interaction pattern of polyelectrolyte microcapsules with different deformability before their use in biomedical applications. In this study, SiO2, poly(sodium-p-styrenesulfonate) (PSS) doped CaCO3 and porous CaCO3 spheres, all about 4μm in diameter, were used as templates to prepare microcapsules with different inner structure and subsequent deformability. As a result, three kinds of covalently assembled poly(allylaminehydrochloride)/glutaraldehyde (PAH/GA) microcapsules with similar size but different deformability under external osmotic pressure were prepared. The impact of different microcapsules on cell viability and functions are studied using smooth muscle cells (SMCs), endothelial cells (ECs) and HepG2 cells. The results demonstrated that viabilities of SMCs, ECs and HepG2 cells were not significantly influenced by either of the three kinds of microcapsules. However, the adhesion ability of SMCs and ECs as well as the mobility of SMCs, ECs and HepG2 cells were significantly impaired after treatment with microcapsules in a deformability dependent manner, especially the microcapsules with lower deformability caused higher impairment on cell functions. The cellular uptake kinetics, uptake pathways, intracellular distribution of microcapsules are further investigated in SMCs to reveal the potential mechanism. The SMCs showed faster uptake rate and exocytosis rate of microcapsules with lower deformability (Cap@CaCO3/PSS and Cap@CaCO3), leading to higher intracellular accumulation of microcapsules with lower deformability and possibly larger retardation of cell functions. The results pointed out that the deformability of microcapsules is an important factor governing the biological performance of microcapsules, which requires careful adjustment for further biomedical applications. PMID:26674230

  18. pH- and sugar-sensitive multilayer films composed of phenylboronic acid (PBA)-modified poly(allylamine hydrochloride) (PBA-PAH) and poly(vinyl alcohol) (PVA): A significant effect of PBA content on the film stability.

    PubMed

    Seno, Masaru; Yoshida, Kentaro; Sato, Katsuhiko; Anzai, Jun-Ichi

    2016-05-01

    Multilayer thin films composed of phenylboronic acid (PBA)-modified poly(allylamine hydrochloride) (PAH), PBA-PAH, with different PBA contents were prepared to study the effect of PBA content on the stability of the films. An alternate deposition of PBA-PAH and poly(vinyl alcohol) (PVA) on the surface of a quartz slide afforded multilayer films through forming boronate ester bonds between PBA-PAH and PVA. The 10-layered (PBA-PAH/PVA)10 films constructed using PBA-PAHs containing 16% and 26% PBA residues were stable in aqueous solutions over the range of pH4.0-10.0, whereas the multilayer films composed of PBA-PAHs with 5.9% and 8.3% PBA decomposed at pH8.0 or lower. The pH-sensitive decomposition of the films was rationalized based on the destabilization of the boronate ester bonds in neutral and acidic solutions. In addition, the (PBA-PAH/PVA)10 films decomposed in glucose and fructose solutions as a result of competitive binding of sugars to PBA-PAH in the films. The sugar response of the films depended on the PBA content in PBA-PAH. The (PBA-PAH/PVA)10 films consisting of 16% and 26% PBA-substituted PBA-PAHs are sensitive to physiological relevant level of glucose at pH7.4 while stable in glucose-free solution, suggesting a potential use of the films in constructing glucose-induced delivery systems. PMID:26952449

  19. Indirect determination of sulfite using a polyphenol oxidase biosensor based on a glassy carbon electrode modified with multi-walled carbon nanotubes and gold nanoparticles within a poly(allylamine hydrochloride) film.

    PubMed

    Sartori, Elen Romão; Vicentini, Fernando Campanhã; Fatibello-Filho, Orlando

    2011-12-15

    The modification of a glassy carbon electrode with multi-walled carbon nanotubes and gold nanoparticles within a poly(allylamine hydrochloride) film for the development of a biosensor is proposed. This approach provides an efficient method used to immobilize polyphenol oxidase (PPO) obtained from the crude extract of sweet potato (Ipomoea batatas (L.) Lam.). The principle of the analytical method is based on the inhibitory effect of sulfite on the activity of PPO, in the reduction reaction of o-quinone to catechol and/or the reaction of o-quinone with sulfite. Under the optimum experimental conditions using the differential pulse voltammetry technique, the analytical curve obtained was linear in the concentration of sulfite in the range from 0.5 to 22 μmol L(-1) with a detection limit of 0.4 μmol L(-1). The biosensor was applied for the determination of sulfite in white and red wine samples with results in close agreement with those results obtained using a reference iodometric method (at a 95% confidence level). PMID:22099673

  20. Plasma Surface Modification of Polyhedral Oligomeric Silsequioxane-Poly(carbonate-urea) Urethane with Allylamine Enhances the Response and Osteogenic Differentiation of Adipose-Derived Stem Cells.

    PubMed

    Chaves, Camilo; Alshomer, Feras; Palgrave, Robert G; Kalaskar, Deepak M

    2016-07-27

    This study present amino functionalization of biocompatible polymer polyhedral oligomeric silsequioxane-poly(carbonate-urea) urethane (POSS-PCU) using plasma polymerization process to induce osteogenic differentiation of adipose derived stem cells (ADSCs). Optimization of plasma polymerization process was carried out keeping cell culture application in mind. Thus, samples were rigorously tested for retention of amino groups under both dry and wet conditions. Physio-chemical characterization was carried out using ninhydrin test, X-ray photon spectroscopy, scanning electron microscopy, and static water contact analysis. Results from physio chemical characterization shows that functionalization of the amino group is not stable under wet conditions and optimization of plasma process is required for stable bonding of amino groups to the POSS-PCU polymer. Optimized samples were later tested in vitro in short and long-term culture to study differentiation of ADSCs on amino modified samples. Short-term cell culture shows that initial cell attachment was significantly (p < 0.001) improved on amine modified samples (NH2-POSS-PCU) compared to unmodified POSS-PCU. NH2-POSS-PCU samples also facilitates osteogenic differentiation of ADSCs as confirmed by immunological staining of cells for extracellular markers such as collagen Type I and osteopontin. Quantification of total collagen and ALP activity also shows significant (p < 0.001) increase on NH2-POSS-PCU samples compared to unmodified POSS-PCU. A pilot study also confirms that these optimized amino modified POSS-PCU samples can further be functionalized using bone inducing peptide such as KRSR using conventional wet chemistry. This further provides an opportunity for biofunctionalization of the polymer for various tissue specific applications. PMID:27384590

  1. Nanosponge formation from organocatalytically-synthesized poly(carbonate) copoplymers

    PubMed Central

    Stevens, David M.; Tempelaar, Sarah; Dove, Andrew P.; Harth, Eva

    2014-01-01

    Advanced organocatalytic synthesis methods were employed to prepare linear poly(carbonate)s with control over functional group incorporation and molecular weight. Pendant allyl or epoxide groups served as reaction partners in thiol-ene click or epoxide–amine reactions with ethylene oxide-containing crosslinking groups to form a panel of six novel poly(carbonate) nanosponges with crosslinking densities ranging from 5%, 10% and 20% via an intermolecular chain-crosslinking approach. PMID:24724044

  2. Inactivation of monoamine oxidase by allylamine does not result in flavin attachment

    SciTech Connect

    Silverman, R.B.; Hiebert, C.K.; Vazquez, M.L.

    1985-11-25

    (1-TH)Allylamine was synthesized by sodium boro(TH)hydride reduction of acrolein followed by direct conversion of the (1-TH)allyl alcohol to N-allylphthalimide with triphenylphosphine, diethylazodicarboxylate, and phthalimide. The protecting group was removed with hydrazine. Inactivation of beef liver mitochondrial monoamine oxidase with (1-TH)allylamine led to incorporation of 1-6 eq of inactivator/active site depending upon the length of incubation time. Inactivation and radioactivity incorporation coincided; however, after 1 eq of tritium was incorporated and 5% enzyme activity remained, additional radioactivity continued to become incorporated into the enzyme. The optical spectrum of the FAD coenzyme changed during inactivation from that of oxidized to reduced flavin. Following dialysis of the inactivated enzyme, the spectrum remained reduced, but denaturation in urea rapidly resulted in reoxidation of the flavin. Under these same denaturing conditions, 96% of the radioactivity associated with the enzyme remained bound, therefore indicating that allylamine attachment is not to the flavin coenzyme but rather to an active site amino acid residue. The adduct also was stable to base and, to a lesser degree, acid treatment. Although allylamine and N-cyclopropylbenzylamine appear to be oxidized by monoamine oxidase to give 3-(amino acid residue) propanal adducts, two different amino acids seem to be involved because of a difference in stability of the adducts. The mechanisms for inactivation of monoamine oxidase by allylamine and reactivation by benzylamine are discussed in relation to previously reported results.

  3. Chemical and biochemical activities of sonochemically synthesized poly(N-isopropyl acrylamide)/silica nanocomposite

    NASA Astrophysics Data System (ADS)

    Chowdhury, Pranesh; Saha, Swadhin Kr; Guha, Arun; Saha, Samar Kr

    2012-11-01

    Poly(N-isopropyl acrylamide) (PNIPA) grafted mesoporous silica nanoparticles (MPSNP) leading to novel inorganic/organic core-shell nanocomposite has been synthesized sonochemically in an aqueous medium without additives like cross-linker, hydrophobic agent, organic solvent. The colloidal stability of MPSNP is enhanced significantly due to encapsulation of the polymer. The composites are characterized by TEM, FTIR and TGA. The chemical and biochemical activities of the sonochemically synthesized materials have been studied in the light of reaction with acid-base, protein adsorption, antimicrobial activity, biocompatibility and nonthrombogenic property. Advantages of sonochemical synthesis compared to other techniques have been evaluated.

  4. Enzyme-synthesized Poly(amine-co-esters) as Non-viral Vectors for Gene Delivery

    PubMed Central

    Liu, Jie; Jiang, Zhaozhong; Zhou, Jiangbing; Zhang, Shengmin; Saltzman, W. Mark

    2010-01-01

    A family of biodegradable poly(amine-co-esters) was synthesized in one step via enzymatic copolymerization of diesters with amino-substituted diols. Diesters of length C4–C12 (i.e., from succinate to dodecanedioate) were successfully copolymerized with diethanolamines with either an alkyl (methyl, ethyl, n-butyl, t-butyl) or an aryl (phenyl) substituent on the nitrogen. Upon protonation at slightly acidic conditions, these poly(amine-co-esters) readily turned to cationic polyelectrolytes, which were capable of condensing with polyanionic DNA to form nanometer-sized polyplexes. In vitro screening with pLucDNA revealed that two of the copolymers, poly(N-methyldiethyleneamine sebacate) (PMSC) and poly(N-ethyldiethyleneamine sebacate) (PESC), possessed comparable or higher transfection efficiencies compared to Lipofectamine 2000. PMSC/pLucDNA and PESC/pLucDNA nanoparticles had desirable particle sizes (40–70 nm) for cellular uptake and were capable of functioning as proton sponges to facilitate endosomal escape after cellular uptake. These polyplex nanoparticles exhibited extremely low cytotoxicity. Furthermore, in vivo gene transfection experiments revealed that PMSC is a substantially more effective gene carrier than PEI in delivering pLucDNAto cells in tumors in mice. All these properties suggest that poly(amine-co-esters) are promising non-viral vectors for safe and efficient DNA delivery in gene therapy. PMID:21171165

  5. Selective Oxytrifluoromethylation of Allylamines with CO2.

    PubMed

    Ye, Jian-Heng; Song, Lei; Zhou, Wen-Jun; Ju, Tao; Yin, Zhu-Bao; Yan, Si-Shun; Zhang, Zhen; Li, Jing; Yu, Da-Gang

    2016-08-16

    Reported is the first oxy-trifluoromethylation of allylamines with carbon dioxide (CO2 ) using copper catalysis, thus leading to important CF3 -containing 2-oxazolidones. It is also the first time CO2 , a nontoxic and easily available greenhouse gas, has been used to tune the difunctionalization of alkenes from amino- to oxy-trifluoromethylation. Of particular note, this multicomponent reaction is highly chemo-, regio-, and diastereoselective under redox-neutral and mild reaction conditions. Moreover, these reactions feature good functional-group tolerance, broad substrate scope, easy scalability and facile product diversification. The important products could also be formed with either spirocycles or two adjacent tetrasubstituted carbon centers. PMID:27411560

  6. Temperature and pH responsiveness of poly-(DMAA-co-unsaturated carboxylic acid) hydrogels synthesized by UV-irradiation

    NASA Astrophysics Data System (ADS)

    Kakinoki, Sachiro; Kaetsu, Isao; Nakayama, Masashi; Sutani, Kouichi; Uchida, Kumao; Yukutake, Kouji

    2003-07-01

    Stimuli-responsive polyampholyte hydrogels were synthesized by the copolymerization of dimethylaminoethyl methacrylate (DMAA) and acrylic acid (AAc) or itaconic acid (IAc) by UV-irradiation. Temperature and pH responsiveness of these hydrogels were studied. The temperature responsiveness of poly-(DMAA-co-AAc, IAc) hydrogels shown in change of water content became dull compared to that of DMAA homo-polymer hydrogel. The water content of the poly-(DMAA-co-AAc, IAc) hydrogels showed a minimum at pH 8, and increased in more acidic and alkaline regions. This fact can be attributed to the coexistence of anions and cations in the poly-(DMAA-co-AAc, IAc) hydrogels. The poly-(DMAA-co-AAc, IAc) hydrogels were polyampholyte having both temperature responsiveness and pH responsiveness.

  7. In vivo biocompatibility studies of poly( n-vinyl 2-pyrrolidone/itaconic acid) hydrogels synthesized by γ-rays

    NASA Astrophysics Data System (ADS)

    Özdemir, S.; Özdemir, E.; Tunca, R.; Hazıroǧlu, R.; Şen, M.; Kantoǧlu, Ö.; Güven, O.

    2003-08-01

    In this study, poly( n-vinyl 2-pyrrolidone/itaconic acid) hydrogels have been synthesized by γ-rays in different compositions and their biocompatibility have been investigated as in vivo and some biochemical parameters of mice serum and histology of their tissues have been examined. By these purposes, poly( n-vinyl 2-pyrrolidone/itaconic acid) (P(VP/IA)) hydrogels were implanted to hypersensitive mice (BALB/c). One and a half months after implantation, hydrogel implanted animals were sacrificed by ether anesthesia and the area hydrogel contacted with tissue was investigated by light microscope for histopathological identification of the tissue. Then the total immunoglobulin E (IgE) level was determined by ELISA. Differential white cell count was also made to better understanding of reaction between hydrogel and tissue. These poly( n-vinyl 2-pyrrolidone/itaconic acid) hydrogels can be directly used as biomedical materials.

  8. Poly(vinyl ester) Block Copolymers Synthesized by Reversible Addition−Fragmentation Chain Transfer Polymerizations

    SciTech Connect

    Lipscomb, Corinne E.; Mahanthappa, Mahesh K.

    2009-07-31

    Homopolymerizations and block copolymerizations of vinyl acetate (VAc), vinyl pivalate (VPv), and vinyl benzoate (VBz) by reversible addition-fragmentation chain transfer (RAFT) polymerization have been studied. Polymerizations of VAc initiated with 2,2{prime}-azobis(isobutyronitrile) (AIBN) at 60 C using two different xanthate RAFT agents C{sub 2}H{sub 5}OC(=S)SR (R = -CH(CH{sub 3})CO{sub 2}C{sub 2}H{sub 5} (1) and -CH(CH{sub 3})O{sub 2}CC(CH{sub 3}){sub 3} (2)) were examined to elucidate the dependence of the polydispersities of the resulting polymers on the RAFT agent leaving group R. RAFT agent 2, in which the leaving R-group mimics a growing vinyl ester polymer chain, consistently yields poly(vinyl acetates) having broader polydispersities than those synthesized using 1 (M{sub n} = 3.6-14 kg/mol and M{sub w}/M{sub n} = 1.15-1.33). While VPv exhibits similar controlled polymerization behavior to VAc, RAFT homopolymerizations of VBz mediated by 1 indicate this electron-deficient vinyl ester requires higher temperatures to effect controlled polymerizations to yield polymers having M{sub n} = 4-14 kg/mol and M{sub w}/M{sub n} = 1.29-1.53. Chain extension reactions from xanthate-terminated vinyl ester homopolymers with VAc, VPv, and VBz proceed with variable efficiencies to furnish block copolymers that microphase separate in the melt state as determined by small-angle X-ray scattering.

  9. Superparamagnetic Fe3O4/Poly(N-isopropyl acrylamide) Nanocomposites Synthesized in Inverse Miniemulsions: Magnetic and Particle Properties.

    PubMed

    Cui, Qinmin; Zhu, Shudi; Yan, Yingjie; Ye, Quanlin; Ziener, Ulrich; Cao, Zhihai

    2015-06-01

    In the present study, superparamagnetic Fe3O4/poly(N-isopropyl acrylamide) nanocomposites were synthesized by one-step inverse miniemulsion copolymerization of N-isopropyl acrylamide and N,N'-methylene diacrylamide. The loading of Fe3O4 nanoparticles in the nanocomposites was 27 wt%, and the saturation moment of the nanocomposites was 12.4 emu x g(-1). Fe3O4 nanoparticles were prepared through a coprecipitation method. The amount of stabilizer (poly(acrylic acid)) significantly influenced the size and size distribution of the Fe3O4 nanoparticles, and, therefore, their magnetic properties. Superparamagnetism of the Fe3O4 nanoparticles was preserved in the nanocomposites. The effects of synthetic parameters on the particle properties, namely surfactant loading, concentration of ferrofluid, type of lipophobe and initiator, and amount of cross-linker were investigated. Nanocomposites of Fe3O4/poly(N-isopropyl acrylamide) displayed a guava-like morphology, which they could retain after being redispersed in polar solvents. PMID:26369088

  10. Biodegradable water absorbent synthesized from bacterial poly(amino acid)s.

    PubMed

    Kunioka, Masao

    2004-03-15

    Biodegradable hydrogels prepared by gamma-irradiation from microbial poly(amino acid)s have been studied. pH-Sensitive hydrogels were prepared by the gamma-irradiation of poly(gamma-glutamic acid) (PGA) produced by Bacillus subtilis and poly(epsilon-lysine) (PL) produced by Streptomyces albulus in aqueous solutions. When the gamma-irradiation dose was 19 kGy or more, and the concentration of PGA in water was 2 wt.-% or more, transparent hydrogels could be produced. For the 19 kGy dose, the produced hydrogel was very weak, however, the specific water content (wt. of absorbed water/wt. of dry hydrogel) of this PGA hydrogel was approximately 3,500. The specific water content decreased to 200, increasing when the gamma-irradiation dose was over 100 kGy. Under acid conditions or upon the addition of electrolytes, the PGA hydrogels shrunk. The PGA hydrogel was pH-sensitive and the change in the volume of the hydrogel depended on the pH value outside the hydrogel in the swelling medium. This PGA hydrogel was hydrodegradable and biodegradable. A new novel purifier reagent (coagulant), made from the PGA hydrogels, for contaminated turbid water has been found and developed by Japanese companies. A very small amount of this coagulant (only 2 ppm in turbid water) with poly(aluminum chloride) can be used for the purification of turbid water. A PL aqueous solution also can change into a hydrogel by gamma-irradiation. The specific water content of the PL hydrogel ranged from 20 to 160 depending on the preparation conditions. Under acid conditions, the PL hydrogel swelled because of the ionic repulsion of the protonated amino groups in the PL molecules. The rate of enzymatic degradation of the respective PL hydrogels by a neutral protease was much faster than the rate of simple hydrolytic degradation. PMID:15468223

  11. Syntheses and properties of poly([6. 2]cyclophane-1,5-diene)s: Electroactive polymers

    SciTech Connect

    Guerrero, D.J.

    1993-01-01

    The synthesis and characterization of (E,E)-[6.2]-(2,5)thiophenophane-1,5-diene (2) is described. Ultraviolet and variable temperature [sup 1]H-nmr spectroscopy were used to deduce structural detail of 2 in solution. Cationic cyclopolymerization of 2 gave polymer 3 which has bridged thiophene rings pendant to the polymer backbone. Structural details of polymer 3 are largely based on comparison with its known benzene analogue (1), poly(2-vinylthiophene) (15) and poly(5-methyl-2-vinylthiophene) (17). The thermal and electronic properties of polymer 3 were compared to those of 15. Polymer 3 exhibited conductivity in the 10[sup [minus]3]-10[sup [minus]4] S/cm range when exposed to iodine vapor. Apparent energies of activation for conductivity in iodine saturated polymers 3 and 15 were calculated from conductivity temperature dependence measurements. Differences in conductivity behavior for iodine saturated polymers 1, 3, and 15 are discussed in terms of both charge generation and mobility. The effects of increasing the electric field on photoconductivity and mobility of 1 and 3 are discussed. Utilization of 1 and 3 in the construction of polymer based chemical sensors for iodine is demonstrated. A novel iodine promoted ring opening polymerization of [2,2]-(2,5)thiophenophane (TPP) is presented. Ft-ir studies of the resulting films revealed formation of a poly ((2,5)-thienylene ethylene) type structure. [2.2]-(2,5)-furanophane and [2.2]-(9,10)-anthracenophane treated similarly also gave the corresponding poly(arylene ethylene) polymers. [2.2]paracyclophane, 4-nitro-[2.2]paracyclophane, anti-[2.2]-(1,4)-naphthalenophane and (E,E)-[6.2]paracyclophane-1,5-diene did not give polymer in the presence of iodine. Electrochemical ring opening polymerization of TPP at a Pt anode suggests a radical cationic intermediate during polymerization.

  12. Self-assembly of brush-like poly[poly(ethylene glycol) methyl ether methacrylate] synthesized via aqueous atom transfer radical polymerization.

    PubMed

    Hussain, Hazrat; Mya, Khine Yi; He, Chaobin

    2008-12-01

    Self-assembly of brush-like well-defined poly[poly(ethylene glycol) methyl ether methacrylate] homopolymers, abbreviated as P(PEGMA-475) and P(PEGMA-1100) is investigated in aqueous solution by employing dynamic/static light scattering (DLS/SLS) and transmission electron microscopy (TEM), whereas 475 and 1100 is molar mass of the respective PEGMA macromonomer. The mentioned brush-like homopolymers are synthesized by aqueous ATRP at room temperature. The critical association concentration (CAC) of the synthesized polymers in water depends on the length of the PEG side chains but not on the overall molar mass of the polymer. Thus, approximately the same CAC of approximately 0.35 mg/mL is estimated for various P(PEGMA-1100) samples, and approximately 0.7 mg/mL is estimated for P(PEGMA-475) series. All the investigated P(PEGMA-1100) samples form multimolecular micelles in aqueous solution, where the hydrodynamic size (Rh) and the aggregation number (Nagg) of micelles decreases as the molecular weight of P(PEGMA-1100) increases. This can be attributed to the increased steric hindrances between the PEG side chains in corona of micelles formed by higher molar mass P(PEGMA-1100). The tendency of micelle formation by samples of P(PEGMA-475) series is significantly lower than that of P(PEGMA-1100) series, as demonstrated by their significantly higher CAC and micelles of lower Nagg. The Rh of micelles does not depend strongly on polymer concentration, which suggests that these micelles are formed via the closed association model. Micelles formed by P(PEGMA-1100) series slightly shrink with increase in temperature from 25 to 60 degrees C, while those of P(PEGMA-475) series are found to be insensitive to the same temperature variation. Finally, TEM is carried out to visualize the formed micelles after transferring the aqueous solution to carbon film. PMID:18986178

  13. Degree of branching in hyperbranched poly(glycerol-co-diacid)s synthesized in toluene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperbranched polymers were synthesized by using a Lewis acid (dibutyltin(IV)oxide) to catalyze the polycondensation of glycerol with either succinic acid (n (aliphatic chain length)=2), glutaric acid (n=3) or azelaic acid (n=7) in toluene. These are the first examples of diacid-glycerol hyperbranc...

  14. Preparation and characterization of poly(vinyl alcohol)/graphene nanofibers synthesized by electrospinning

    NASA Astrophysics Data System (ADS)

    Barzegar, Farshad; Bello, Abdulhakeem; Fabiane, Mopeli; Khamlich, Saleh; Momodu, Damilola; Taghizadeh, Fatemeh; Dangbegnon, Julien; Manyala, Ncholu

    2015-02-01

    We report on the synthesis and characterization of electrospun polyvinyl alcohol (PVA)/graphene nanofibers. The samples produced were characterized by Raman spectroscopy for structural and defect density analysis, scanning electron microscopy (SEM) for morphological analysis, and thermogravimetric (TGA) for thermal analysis. SEM measurements show uniform hollow PVA fibers formation and excellent graphene dispersion within the fibers, while TGA measurements show the improved thermal stability of PVA in the presence of graphene. The synthesized polymer reinforced nanofibers have potential to serve in many different applications such as thermal management, supercapacitor electrodes and biomedical materials for drug delivery.

  15. Temperature-dependent properties of silver-poly(methylmethacrylate) nanocomposites synthesized by in-situ technique

    PubMed Central

    2014-01-01

    Ag/PMMA nanocomposites were successfully synthesized by in-situ technique. Transmission electron microscopy (TEM) images show that the particles are spherical in shape and their sizes are dependent on temperature. The smallest particle achieved high stability as indicated from Zeta sizer analysis. The red shift of surface plasmon resonance (SPR) indicated the increases of particle sizes. X-ray diffraction (XRD) patterns exhibit a two-phase (crystalline and amorphous) structure of Ag/PMMA nanocomposites. The complexation of Ag/PMMA nanocomposites was confirmed using Raman spectroscopy. Fourier transform infrared spectroscopy spectra confirmed that the bonding was dominantly influenced by the PMMA and DMF solution. Finally, thermogravimetric analysis (TGA) results indicate that the total weight loss increases as the temperature increases. PMID:24450850

  16. Structural and optical characteristics of silver/poly(N-vinyl-2-pyrrolidone) nanosystems synthesized by γ-irradiation

    NASA Astrophysics Data System (ADS)

    Jovanović, Željka; Radosavljević, Aleksandra; Šiljegović, Milorad; Bibić, Nataša; Mišković-Stanković, Vesna; Kačarević-Popović, Zorica

    2012-11-01

    Silver nanoparticles (AgNPs) were synthesized in situ by γ-irradiation using poly(N-vinyl-2-pyrrolidone) (PVP) as a capping agent. The concentration, molecular weight and the structure (crosslinked and interpenetrated network) of PVP were varied, in order to determine the influence of the capping agent in the radiolytic synthesis of the Ag/PVP nanosystems. Transmission electron microscopy (TEM) showed that AgNPs obtained from the solutions containing higher PVP concentration and higher molecular weight were spherical in shape, with narrow size distribution and a diameter of˜6 nm, while slightly larger rod-shaped silver agglomerates, with bimodal nanoparticle size distribution and diameters of ˜10 nm and ˜20 nm were obtained from the solutions containing lower PVP concentration and lower molecular weight. Strong plasmon coupling and extending of plasmon resonance was observed by UV-vis spectroscopy, as a result of formation of nanorod-like agglomerates. Crosslinked and interpenetrated network did not affect the structure of synthesized AgNPs. Ag/PVP nanocomposite, in the form of thin film, was obtained by solvent evaporation from Ag/PVP colloid solution with 10 wt% of PVP, and characterized by FTIR spectroscopy. The interactions in Ag/PVP nanocomposite are shown to be the result of the coordination bonding between AgNPs and nitrogen from pyrrolidone ring of PVP. The optical properties of investigated Ag/PVP nanosystems, as measured by the values of optical band gap, Eg, are mainly the consequence of the interparticle distance as a result of the concentration and the structure of surrounding PVP macromolecules.

  17. Preparation, Characterization, and Size Control of Chemically Synthesized CdS Nanoparticles Capped with Poly(ethylene glycol)

    NASA Astrophysics Data System (ADS)

    Seoudi, R.; Allehyani, S. H. A.; Said, D. A.; Lashin, A. R.; Abouelsayed, A.

    2015-10-01

    We prepared cadmium sulfide (CdS) nanoparticles of a specific size via chemical precipitation at room temperature and characterized them using high-resolution transmission electron microscopy, x-ray powder diffraction, ultraviolet-visible spectroscopy, and Fourier-transform infrared (FTIR) measurements. The results showed that the samples were grown with a cubic phase; the particle size could be changed from 2 nm to 4 nm by varying the molar ratios of the precursors (cadmium chloride and sodium sulfide) in the presence of poly(ethylene glycol) (PEG) as an effective capping agent. The optical bandgap of the synthesized nanoparticles was calculated and ranged from 2.73 eV to 2.92 eV depending on the particle size. A large blue-shift from the bulk bandgap (2.42 eV) was observed owing to the quantum size effect. Surface passivation and adsorption of PEG on the CdS nanoparticles was explained on the basis of FTIR measurements; two bands were observed at 476 cm-1 and 622 cm-1, corresponding to cadmium and sulfide stretching vibrations. We conclude that particle size can be controlled by varying the molar ratios of the precursors. Owing to the PEG encapsulation, the as-prepared samples were extremely stable over time.

  18. Modulation of phosphoinositide metabolism in aortic smooth muscle cells by allylamine

    SciTech Connect

    Cox, L.R.; Murphy, S.K.; Ramos, K. )

    1990-08-01

    Aortic smooth muscle cells (SMC) modulate from a contractile to a proliferative phenotype upon subchronic exposure to allylamine. The present studies were designed to determine if this phenotypic modulation is associated with alterations in the metabolism of membrane phosphoinositides. 32P incorporation into phosphatidylinositol 4-phosphate (PIP), phosphatidylinositol 4,5-bisphosphate (PIP2), and phosphatidic acid (PA) was lower by 31, 35, and 22%, respectively, in SMC from allylamine-treated animals relative to controls. In contrast, incorporation of (3H)myoinositol into inositol phosphates did not differ in allylamine cells relative to control cells. Exposure to dibutyryl (db) cAMP (0.2 mM) and theophylline (0.1 mM) reduced 32P incorporation into PIP and PIP2 in SMC from both experimental groups. Under these conditions, a decrease in (3H)myoinositol incorporation into inositol 1-phosphate was only observed in allylamine cells. The effects of db cAMP and theophylline in allylamine and control SMC correlated with a marked decrease in cellular proliferation. These results suggest that alterations in phosphoinositide synthesis and/or degradation contribute to the enhanced proliferation of SMC induced by allylamine. To further examine this concept, the effects of agents which modulate protein kinase C (PKC) activity were evaluated. Sphingosine (125-500 ng/ml), a PKC inhibitor, decreased SMC proliferation in allylamine, but not control cells. 12-O-Tetradecanoylphorbol-13-acetate (1-100 ng/ml), a PKC agonist, stimulated proliferation in control cells, but inhibited proliferation in cells from allylamine-treated animals. We conclude that allylamine-induced phenotypic modulation of SMC is associated with alterations in phosphoinositide metabolism.

  19. Micelles of enzymatically synthesized PEG-poly(amine-co-ester) block copolymers as pH-responsive nanocarriers for docetaxel delivery.

    PubMed

    Zhang, Xiaofang; Liu, Bo; Yang, Zhe; Zhang, Chao; Li, Hao; Luo, Xingen; Luo, Huiyan; Gao, Di; Jiang, Qing; Liu, Jie; Jiang, Zhaozhong

    2014-03-01

    A series of PEGylated poly(amine-co-ester) terpolymers were successfully synthesized in one step via lipase-catalyzed copolymerization of ω-pentadecalactone (PDL), diethyl sebacate (DES), and N-methyldiethanolamine (MDEA) comonomers in the presence of poly(ethylene glycol) methyl ether as a chain-terminating agent. The resultant amphiphilic poly(ethylene glycol)-poly(PDL-co-MDEA-co-sebacate) (PEG-PPMS) block copolymers consisted of hydrophilic PEG chain segments and hydrophobic random PPMS chain segments, which self-assembled in aqueous medium to form stable, nanosized micelles at physiological pH of 7.4. Upon decreasing the medium pH from 7.4 to 5.0, the copolymer micelles swell significantly due to protonation of the amino groups in the micelle PPMS cores. Correspondingly, docetaxel (DTX)-encapsulated PEG2K-PPMS copolymer micelles showed gradual sustained drug release at pH of 7.4, but remarkably accelerated DTX release at acidic pH of 5.0. The drug-loaded micelle particles were readily internalized by SK-BR-3 cancer cells and, compared to free DTX drug, DTX-loaded micelles of the copolymers with optimal compositions exhibited enhanced potency against the cells. Biodegradable PEG-PPMS copolymer micelles represent a new type of promising, pH-responsive nanocarriers for anticancer drug delivery, and the drug release rate from the micelles can be systematically controlled by both pH and the copolymer composition. PMID:24398083

  20. The effect of poly vinyl alcohol (PVA) surfactant on phase formation and magnetic properties of hydrothermally synthesized CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Jalalian, M.; Mirkazemi, S. M.; Alamolhoda, S.

    2016-12-01

    Nanoparticles of CoFe2O4 were synthesized by hydrothermal process at 190 °C with and without poly vinyl alcohol (PVA) addition using treatment durations of 1.5-6 h. The synthesized powders were characterized with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), Field emission scanning electron microscope (FESEM) and vibration sample magnetometer (VSM) techniques. XRD results show presence of CoFe2O4 as the main phase and Co3O4 as the lateral phase in some samples. The results show that in the samples synthesized without PVA addition considerable amount of lateral phase is present after 3 h of hydrothermal treatment while with PVA addition this phase is undetectable in the XRD patterns of the sample synthesized at the same conditions. Microstructural studies represent increasing of particle size with increasing of hydrothermal duration and formation of coarser particles with PVA addition. The highest maximum magnetization (Mmax) values in both of the samples that were synthesized with and without PVA addition are about 59 emu/g that were obtained after 4.5 h of hydrothermal treatment. Intrinsic coercive field (iHc) value of the sample without PVA addition increases from 210 to 430 Oe. While with PVA addition the iHc value changes from 83 Oe to 493 Oe. The mechanism of changes in Mmax and iHc values has been explained.

  1. Improvement of the titanium implant biological properties by coating with poly (ɛ-caprolactone)-based hybrid nanocomposites synthesized via sol-gel

    NASA Astrophysics Data System (ADS)

    Catauro, Michelina; Bollino, Flavia; Papale, Ferdinando

    2016-05-01

    When bioactive coatings are applied to medical implants by means of sol-gel dip coating technique, the biological proprieties of the implant surface can be modified to match the properties of the surrounding tissues. In this study organo-inorganic nanocomposites materials were synthesized via sol-gel. They consisted of an inorganic zirconium-based and silica-based matrix, in which a biodegradable polymer (the poly-ɛ-caprolactone, PCL) was incorporated in different weight percentages. The synthesized materials, in sol phase, were used to dip-coat a substrate of commercially pure titanium grade 4 (CP Ti gr. 4) in order to improve its biological properties. A microstructural analysis of the obtained films was carried out by scanning electron microscopy (SEM) and attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FT-IR). Biological proprieties of the coated substrates were investigated by means of in vitro tests.

  2. Lasalocid acid as a lipophilic carrier ionophore for allylamine: Spectroscopic, crystallographic and microbiological investigation

    NASA Astrophysics Data System (ADS)

    Huczyński, Adam; Janczak, Jan; Rutkowski, Jacek; Łowicki, Daniel; Pietruczuk, Anna; Stefańska, Joanna; Brzezinski, Bogumil; Bartl, Franz

    2009-11-01

    A new complex of lasalocid acid with allylamine (LAS-AM) is synthesised and studied by X-ray, FT-IR, 1H NMR and 13C NMR, ESI MS methods. In the solid state allylamine is protonated and all protons of NH 3+ are hydrogen bonded. We show that in the gas, liquid and solid states lasalocid forms 1:1 complexes with allylamine and that its structures of all states are comparable, which indicates that the complex LAS-AM is very stable. The stability of the LAS-AM complex is achieved by some intra-molecular hydrogen bonds. Due to these interactions the outside of the complex is hydrophobic enabling its transport across the biological membranes. This property of the complex is reflected in its anti-microbial activity, which is discussed.

  3. Chiral Brønsted Acid Catalyzed Enantioselective Phosphonylation of Allylamine via Oxidative Dehydrogenation Coupling.

    PubMed

    Cheng, Ming-Xing; Ma, Ran-Song; Yang, Qiang; Yang, Shang-Dong

    2016-07-01

    A new strategy for the synthesis of chiral α-amino phosphonates by enantioselective C-H phosphonylation of allylamine with phosphite in the presence of a chiral Brønsted acid catalyst has been developed. This protocol successfully integrates direct C-H oxidation with asymmetric phosphonylation and exhibits high enantioselectivity. PMID:27331612

  4. Effects of naftifine and terbinafine, two allylamine antifungal drugs, on selected functions of human polymorphonuclear leukocytes.

    PubMed Central

    Vago, T; Baldi, G; Colombo, D; Barbareschi, M; Norbiato, G; Dallegri, F; Bevilacqua, M

    1994-01-01

    Many antimycotic agents negatively affect the natural immune response. Typically, these drugs impair polymorphonuclear leukocyte (PMN) production of superoxide anion, chemotaxis, or the killing of pathogens. Allylamines are a new class of antimycotic compounds with a new mechanism of antifungal action, i.e., inhibition of the fungal squalene epoxidase. The trial that we describe aimed to evaluate the effects of two allylamines, terbinafine and naftifine, on selected functions of PMNs, i.e., superoxide anion production, chemotaxis, and killing of Candida albicans blastospores. Terbinafine and naftifine on their own did not affect superoxide anion production when they were added to PMNs. When PMNs were preincubated with allylamines and were then stimulated by N-formyl-Met-Leu-Phe or phorbol 12-myristate 13-acetate, superoxide anion production was increased (priming effect). Since intracellular free calcium (Ca2+i) is involved in the control of superoxide anion production, we evaluated the effects of the allylamines on the Ca2+i concentration ([Ca2+]i). In the presence of terbinafine or naftifine, the [Ca2+]i increased in a dose-dependent manner; the source of Ca2+i was not extracellular since it was not affected by extracellular calcium chelation with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. In the presence of terbinafine or naftifine, chemotaxis of PMNs was not impaired. Terbinafine and naftifine slightly but significantly increased the killing of C. albicans blastospores (P < 0.05 at 10 and 100 microM). In conclusion, in contrast to imidazole-like drugs, the allylamine antimycotic compounds terbinafine and naftifine enhance selected functions of PMNs. PMID:7872755

  5. Electro-optical properties of one pot synthesized polyindole in the presence of poly(vinyl acetate)

    NASA Astrophysics Data System (ADS)

    Bhagat, D. J.; Dhokane, G. R.

    2015-05-01

    Polyindole was prepared in the presence of poly(vinyl acetate) through a chemical polymerization technique. The indole monomer was polymerized using ferric chloride as an oxidant. Electrical conductivity measurements were performed through a two probe technique. The prepared composites were analyzed by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), energy dispersive x-ray spectroscopy (EDAX), and ultraviolet-visible (UV-VIS) spectroscopy. The DC conductivity was found to be 4.46 × 10-6 S/cm at 383 K. An attempt has been made to investigate the electrooptical properties of PIN/PVAc composite films.[Figure not available: see fulltext.

  6. Syntheses and physical characterization of new aliphatic triblock poly(L-lactide-b-butylene succinate-b-L-lactide)s bearing soft and hard biodegradable building blocks.

    PubMed

    Ba, Chaoyi; Yang, Jing; Hao, Qinghui; Liu, Xiaoyun; Cao, Amin

    2003-01-01

    This study presents chemical syntheses and physical characterization of a new aliphatic poly(L-lactide-b-butylene succinate-b-L-lactide) triblock copolyester with soft and hard biodegradable building blocks. First, poly(butylene succinate) (PBS) prepolymers terminated with hydroxyl functional groups were synthesized through melt polycondensation from succinic acid and 1,4-butanediol. Further, a series of new PLLA-b-PBS-b-PLLA triblock copolyesters bearing various average PLLA block lengths were prepared via ring opening polymerization of L-lactide with the synthesized hydroxyl capped PBS prepolymer (Mn = 4.9 KDa) and stannous octanoate as the macroinitiator and catalyst, respectively. By means of GPC, NMR, FTIR, DSC, TGA, and wide-angle X-ray diffractometer (WAXD), the macromolecular structures and physical properties were intensively studied for these synthesized PBS prepolymer and PLLA-b-PBS-b-PLLA triblock copolyesters. 13C NMR and GPC experimental results confirmed the formation of sequential block structures without any detectable transesterification under the present experimental conditions, and the molecular weights of triblock copolyesters could be readily regulated by adjusting the feeding molar ratio of L-lactide monomer to the PBS macroinitiator. DSC measurements showed all single glass transitions, and their glass transition temperatures were found to be between those of PLLA and PBS, depending on the lengths of PLLA blocks. It was noteworthy that the segmental flexibilities of the hard PLLA blocks were found to be remarkably enhanced by the more flexible PBS block partner, and the PBS and PLLA building blocks were well mixed in the amorphous regions. Results of TGA analyses indicated that thermal degradation and stabilities of the PLLA blocks strongly depended on the average PLLA block lengths of triblock copolyesters. In addition, FTIR and WAXD results showed the coexistence of the assembled PLLA and PBS crystal structures when the average PLLA block

  7. A facile route to synthesize silver nanoparticles in polyelectrolyte capsules.

    PubMed

    Anandhakumar, S; Raichur, Ashok M

    2011-06-01

    We are reporting a novel green approach to incorporate silver nanoparticles (NPs) selectively in the polyelectrolyte capsule shell for remote opening of polyelectrolyte capsules. This approach involves in situ reduction of silver nitrate to silver NPs using PEG as a reducing agent (polyol reduction method). These nanostructured capsules were prepared via layer by layer (LbL) assembly of poly(allylamine hydrochloride) (PAH) and dextran sulfate (DS) on silica template followed by the synthesis of silver NPs and subsequently the dissolution of the silica core. The size of silver nanoparticles synthesized was 60±20 nm which increased to 100±20 nm when the concentration of AgNO(3) increased from 25 mM to 50 mM. The incorporated silver NPs induced rupture and deformation of the capsules under laser irradiation. This method has advantages over other conventional methods involving chemical agents that are associated with cytotoxicity in biological applications such as drug delivery and catalysis. PMID:21333503

  8. Electrochemical biosensor based on glucose oxidase encapsulated within enzymatically synthesized poly(1,10-phenanthroline-5,6-dione).

    PubMed

    Ciftci, Hakan; Oztekin, Yasemin; Tamer, Ugur; Ramanaviciene, Almira; Ramanavicius, Arunas

    2014-11-01

    This study is focused on the investigation of electrocatalytic effect of glucose oxidase (GOx) immobilized on the graphite rod (GR) electrode. The enzyme modified electrode was prepared by encapsulation of immobilized GOx within enzymatically formed poly(1,10-phenanthroline-5,6-dione) (pPD) film. The electrochemical responses of such enzymatic electrode (pPD/GOx/GR) vs. different glucose concentrations were examined chronoamperometrically in acetate-phosphate buffer solution (A-PBS), pH 6.0, under aerobic or anaerobic conditions. Amperometric signals of the pPD/GOx/GR electrode exhibited well-defined hyperbolic dependence upon glucose concentration. Amperometric signals at 100mM of glucose were 41.17 and 32.27 μA under aerobic and anaerobic conditions, respectively. Amperometric signals of the pPD/GOx/GR electrode decreased by 6% within seven days. The pPD/GOx/GR electrode showed excellent selectivity in the presence of dopamine and uric acid. Furthermore it had a good reproducibility and repeatability with standard deviation of 9.4% and 8.0%, respectively. PMID:25454754

  9. Syntheses, characterizations and photoluminescent properties of two novel coordination polymers constructed by poly-carboxylate and N-heterocyclic ligands

    NASA Astrophysics Data System (ADS)

    Yan, Li; Li, Chuanbi; Wang, Yifei

    2013-03-01

    Two novel coordination compounds constructed from aromatic acid and N-heterocyclic ligands, namely, [Mn(dipt)2(n-BDC)]n (1) [dipt = 2-(2,4-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, n-BDC = 5-nitrobenzene-1,3-dioic acid] and [Cu2(bip)2(m-BDC)2(H2O)3]ṡ2H2O (2) [bip = 2-(4-bromophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, m-BDC = isophthalic acid] have been synthesized by hydrothermal reaction: compounds 1 and 2 were characterized by elemental analysis, infrared spectrum (IR), single crystal X-ray diffraction and thermogravimetric analysis (TGA). In 1, n-BDC anions link the adjacent Mn(II) centers to generate a one-dimensional (1D) zigzag chain. Furthermore, unprecedented intersections of C-H⋯O bonds lead 1D chain into 2D sheet supra-molecular architecture. Differed from 1, 2 exhibits 0D structure, and displays a 2D topology via strong H-bond and π-π stacking interactions. TG analysis shows clear courses of weight loss, which corresponds to the decomposition of different ligands. The structure-related solid-state fluorescence spectra of compounds 1 and 2 have been determined, and the result displays that compounds 1 and 2 are potential luminescent material.

  10. Mononuclear and binuclear sandwich copper(II) complexes with poly(pyrazolyl)borate ligands: Syntheses, structures and properties

    NASA Astrophysics Data System (ADS)

    Xing, Y. H.; Zhang, X. J.; Sun, Z.; Han, J.; Zhang, Y. H.; Zhang, B. L.; Ge, M. F.; Niu, S. Y.

    2007-12-01

    A series of Cu(II) complexes Cu 2[μ-pz] 2[HB(pz) 3] 2 ( 1), Cu[H 2B(pz) 2] 2 ( 2), Cu[HB(pz) 3] 2 ( 3), Cu[HB(pz Me2) 3] 2 ( 4), Cu[B(pz) 4] 2 ( 5) (pz = pyrazole), have been synthesized and characterized by elemental analysis, IR, UV-vis, X-ray diffraction, thermal analysis and theoretical analysis. The IR spectra give the Cu-N vibration modes at 322, 366, 344, 387, and 380 cm -1 in complexes 1- 5, respectively. The UV spectra show all the complexes have same UV absorption at 232 nm; there is another band at 332 nm for complexes 1, 2 and 4, while for complexes 3 and 5, the bands are at 272 and 308 nm, respectively. Complex 1 has a binuclear structure in which two pyrazole ligands bridge two Cu-Tp units. In 2- 5, the Cu(II) centers are coordinated with dihydrobis(pyrazolyl)borate (Bp), hydrotris(pyrazolyl)borate (Tp), hydrotris(3,5-Me2pyrazolyl)borate (Tp'), tetrakis(pyrazolyl)borate (Tkp) respectively to form a mononuclear structure. The results of thermal analysis for complexes 1- 5 are discussed too.

  11. Micron- and nano-sized poly(N-isopropylacrylamide-co-acrylic acid) latex syntheses and their applications for controlled drug release.

    PubMed

    Lue, Shingjiang Jessie; Chen, Bo-Wei; Shih, Chao-Ming; Chou, Feng-Yi; Lai, Jui-Yang; Chiu, Wen-Yen

    2013-08-01

    Thermo-sensitive poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAAm-co-AAc)) latex particles were prepared with and without sodium dodecyl sulfate (SDS) surfactant via an emulsion polymerization method. The P(NIPAAm-co-AAc) latex particle sizes were approximately 1.1 microm without SDS addition and the particle sizes were in the nanometer range (59 nm) with SDS at its critical micelle concentration (CMC) of 8 mM. We propose a scheme to demonstrate how the SDS concentration affects the synthesized latex particle size. The lower critical solution temperature (LCST) was hardly influenced by the SDS level but increased with the AAc concentration. The PNIPAAm-co-AAc latex particles were employed as thermo-sensitive drug carriers and 4-acetamidophenol was loaded to study the drug release rates from the nano-gels. The effective drug diffusion coefficients within the nano-gels varied as a function of particle size, AAc content, and temperature. The smaller or AAc-rich hydrogel particles provided sustainable drug release property and have potential use in biomedical applications. PMID:23882758

  12. Swelling of poly(N-isopropylacrylamide) P(NIPA)-based hydrogels with bacterial-synthesized prodigiosin for localized cancer drug delivery.

    PubMed

    Danyuo, Y; Dozie-Nwachukwu, S; Obayemi, J D; Ani, C J; Odusanya, O S; Oni, Y; Anuku, N; Malatesta, K; Soboyejo, W O

    2016-02-01

    We present the results of swelling experiments on poly(N-isopropylacrylamide) P(NIPA)-based hydrogels. The swelling characteristics of P(NIPA)-based homo-polymer and P(NIPA)-based co-polymers with Acrylamide (AM) and Butyl Methacrylate (BMA), were studied using weight gain experiments. The swelling due to the uptake of biosynthesized cancer drug, prodigiosin (PG), was compared to swelling in controlled environments (distilled water (DW), paclitaxel™ (PT) and bromophenol blue (BB)). PG was synthesized with Serratia marcescens (SM) subsp. marcescens bacteria. The mechanisms of drug diffusion and swelling of P(NIPA)-based hydrogels are also elucidated along with characterizing the heterogeneous porous structure of the P(NIPA)-based hydrogels. High Performance Liquefied Chromatography (HPLC) analysis revealed the purity of the biosynthesized prodigiosin to be 92.8%. PG was then absorbed by P(NIPA)-based hydrogels at temperatures between 28-48°C. This is a temperature range that might be encountered during the implantation of biomedical devices for localized cancer treatment via drug delivery and hyperthermia. The results obtained are shown to provide insights for the design of implantable biomedical devices for the localized treatment of breast cancer. PMID:26652344

  13. Osteoblasts with impaired spreading capacity benefit from the positive charges of plasma polymerised allylamine.

    PubMed

    Kunz, F; Rebl, H; Quade, A; Matschegewski, C; Finke, B; Nebe, J B

    2015-01-01

    Bone diseases such as osteoporosis, osteoarthritis and rheumatoid arthritis, impinge on the performance of orthopaedic implants by impairing bone regeneration. For this reason, the development of effective surface modifications supporting the ingrowth of implants in morbid bone tissue is essential. Our study is designed to elucidate if cells with restricted cell-function limiting adhesion processes benefit from plasma polymer deposition on titanium. We used the actin filament disrupting agent cytochalasin D (CD) as an experimental model for cells with impaired actin cytoskeleton. Indeed, the cell's capacity to adhere and spread was drastically reduced due to shortened actin filaments and vinculin contacts that were smaller. The coating of titanium with a positively charged nanolayer of plasma polymerised allylamine (PPAAm) abrogated these disadvantages in cell adhesion and the CD-treated osteoblasts were able to spread significantly. Interestingly, PPAAm increased spreading by causing enhanced vinculin number and contact length, but without significantly reorganising actin filaments. PPAAm with the monomer allylamine was deposited in a microwave-excited low-pressure plasma-processing reactor. Cell physiology was monitored by flow cytometry and confocal laser scanning microscopy, and the length and number of actin filaments was quantified by mathematical image processing. We showed that biomaterial surface modification with PPAAm could be beneficial even for osteoblasts with impaired cytoskeleton components. These insights into in vitro conditions may be used for the evaluation of future strategies to design implants for morbid bone tissue. PMID:25738585

  14. Increasing binding density of yeast cells by control of surface charge with allylamine grafting to ion modified polymer surfaces.

    PubMed

    Tran, Clara T H; Kondyurin, Alexey; Chrzanowski, Wojciech; Bilek, Marcela M M; McKenzie, David R

    2014-10-01

    Plasma immersion ion implantation (PIII) treatment of polymers creates a biointerface capable of direct covalent immobilization of biomolecules. The immobilization of protein molecules is achieved by covalent bonds formed between embedded radicals on the treated surface and amino acid side chains and cells can be immobilized through cell-wall proteins. The attachment density of negatively charged entities on a PIII treated surface is inhibited by its negative surface charge at neutral pH. To reduce the negative charge of PIII treated surfaces in phosphate buffer (pH 7.4, 11mM), we develop an effective approach of grafting allylamine monomers onto the treated surface. The results reveal reactions between allylamine and radicals on the PIII treated surface. One of these triggers polymerization, increasing the number of amine groups grafted. As a consequence, the PIII treated polystyrene surface after allylamine exposure becomes more hydrophobic and less negatively charged in phosphate buffer. Using yeast cells as an example, we have shown a significant improvement (6-15 times) of cell density immobilized on the PIII treated surface after exposure to allylamine. PMID:25092587

  15. NF-κB and Matrix-Dependent Regulation of Osteopontin Promoter Activity in Allylamine-Activated Vascular Smooth Muscle Cells

    PubMed Central

    Williams, E. Spencer; Wilson, Emily; Ramos, Kenneth S.

    2012-01-01

    Repeated cycles of oxidative injury by allylamine in vivo induce a proliferative rat vascular (aortic) smooth muscle cell (vSMC) phenotype characterized by matrix-dependent enhancement of mitogenic sensitivity, changes in cell surface integrin expression, and osteopontin (opn) overexpression. Here, we show that constitutive and mitogen-stimulated NF-κB DNA binding activity is enhanced in allylamine vSMCs. Matrix-specific changes in cellular Rel protein expression were observed in allylamine vSMCs. The NF-κB DNA binding element located at −1943 in the 5′-UTR strongly inhibited opn promoter activity in allylamine vSMCs, and this response was regulated by the extracellular matrix. Constitutive increases in opn promoter activity were only seen when allylamine cells were seeded on a fibronectin substrate, and this response was independent of the NF-κB DNA binding sequence within the regulatory region. Thus, NF-κB functions as a critical regulator of the allylamine-induced proliferative phenotype in vSMCs. PMID:22315656

  16. Aging of plasma-polymerized allylamine nanofilms and the maintenance of their cell adhesion capacity.

    PubMed

    Finke, Birgit; Rebl, Henrike; Hempel, Frank; Schäfer, Jan; Liefeith, Klaus; Weltmann, Klaus-Dieter; Nebe, J Barbara

    2014-11-25

    The long-term stability and γ-sterilisability of bioactive layers is the precondition for the application of implants. Thus, aging processes of a microwave deposited, plasma polymerized allylamine nanofilm (PPAAm) with positively charged amino groups were evaluated concerning physicochemical characteristics and cell adhesion capacity over the course of one year. XPS, FT-IR, surface free energy, and water contact angle measurements elucidated not only the oxidation of the PPAAm film due to atmospheric oxygen reacting with surface free radicals but also the influence of atmospheric moisture during sample storage in ambient air. Surprisingly, within 7 days 70% of the primary amino groups are lost and mostly converted into amides. A positive zeta-potential was verified for half a year and longer. Increasing polar surface groups and a water contact angle shift from 60° to 40° are further indications of altered surface properties. Nevertheless, MG-63 human osteoblastic cells adhered and spread out considerably on aged and additionally γ-sterilized PPAAm layers deposited on polished titanium alloys (Ti-6Al-4V_P). These cell-relevant characteristics were highly significant over the whole period of one year and may not be related to the existence of primary amino groups. Rather, the oxidation products, the chemical amide group, that is, seem to support the attachment of osteoblasts at all times up to one year. PMID:25356776

  17. Magnetic Relaxation Switch Detecting Boric Acid or Borate Ester through One-Pot Synthesized Poly(vinyl alcohol) Functionalized Nanomagnetic Iron Oxide.

    PubMed

    Zhang, Guilong; Lu, Shiyao; Qian, Junchao; Zhong, Kai; Yao, Jianming; Cai, Dongqing; Cheng, Zhiliang; Wu, Zhengyan

    2015-08-01

    We developed a highly efficient magnetic relaxation switch (MRS) system based on poly(vinyl alcohol) functionalized nanomagnetic iron oxide (PVA@NMIO) particles for the detection of boric acid or borate ester (BA/BE). It was found that the addition of BA/BE induced the aggregation of PVA@NMIO particles, resulting in a measurable change in the T2 relaxation time in magnetic resonance measurements. The main mechanism was proposed that the electron-deficient boron atoms of BA/BE caused the aggregation of PVA@NMIO particles through covalent binding to the hydroxyl groups of PVA. This novel detection system displayed excellent selectivity, high sensitivity, and rapid detection for BA/BE. Thus, this system may provide a great application prospect for detection of BA/BE. PMID:26171794

  18. A poly(acrylonitrile)-functionalized porous aromatic framework synthesized by atom-transfer radical polymerization for the extraction of uranium from seawater

    DOE PAGESBeta

    Yue, Yanfeng; Zhang, Chenxi; Tang, Qing; Mayes, Richard T.; Liao, Wei -Po; Liao, Chen; Tsouris, Costas; Stankovich, Joseph J.; Chen, Jihua; Hensley, Dale K.; et al

    2015-10-30

    In order to ensure a sustainable reserve of fuel for nuclear power generation, tremendous research efforts have been devoted to developing advanced sorbent materials for extracting uranium from seawater. In this work, a porous aromatic framework (PAF) was surface-functionalized with poly(acrylonitrile) through atom-transfer radical polymerization (ATRP). Batches of this adsorbent were conditioned with potassium hydroxide (KOH) at room temperature or 80 °C prior to contact with a uranium-spiked seawater simulant, with minimal differences in uptake observed as a function of conditioning temperature. A maximum capacity of 4.81 g-U/kg-ads was obtained following 42 days contact with uranium-spiked filtered environmental seawater, whichmore » demonstrates a comparable adsorption rate. A kinetic investigation revealed extremely rapid uranyl uptake, with more than 80% saturation reached within 14 days. Furthermore, relying on the semiordered structure of the PAF adsorbent, density functional theory (DFT) calculations reveal cooperative interactions between multiple adsorbent groups yield a strong driving force for uranium binding.« less

  19. A poly(acrylonitrile)-functionalized porous aromatic framework synthesized by atom-transfer radical polymerization for the extraction of uranium from seawater

    SciTech Connect

    Yue, Yanfeng; Zhang, Chenxi; Tang, Qing; Mayes, Richard T.; Liao, Wei -Po; Liao, Chen; Tsouris, Costas; Stankovich, Joseph J.; Chen, Jihua; Hensley, Dale K.; Abney, Carter W.; Jiang, De-en; Brown, Suree; Dai, Sheng

    2015-10-30

    In order to ensure a sustainable reserve of fuel for nuclear power generation, tremendous research efforts have been devoted to developing advanced sorbent materials for extracting uranium from seawater. In this work, a porous aromatic framework (PAF) was surface-functionalized with poly(acrylonitrile) through atom-transfer radical polymerization (ATRP). Batches of this adsorbent were conditioned with potassium hydroxide (KOH) at room temperature or 80 °C prior to contact with a uranium-spiked seawater simulant, with minimal differences in uptake observed as a function of conditioning temperature. A maximum capacity of 4.81 g-U/kg-ads was obtained following 42 days contact with uranium-spiked filtered environmental seawater, which demonstrates a comparable adsorption rate. A kinetic investigation revealed extremely rapid uranyl uptake, with more than 80% saturation reached within 14 days. Furthermore, relying on the semiordered structure of the PAF adsorbent, density functional theory (DFT) calculations reveal cooperative interactions between multiple adsorbent groups yield a strong driving force for uranium binding.

  20. Novel pH-responsive polymeric micelles prepared through self-assembly of amphiphilic block copolymer with poly-4-vinylpyridine block synthesized by mechanochemical solid-state polymerization.

    PubMed

    Kondo, Shin-ichi; Asano, Yuna; Koizumi, Natsumi; Tatematsu, Kenjiro; Sawama, Yuka; Sasai, Yasushi; Yamauchi, Yukinori; Kuzuya, Masayuki; Kurosawa, Shigeru

    2015-01-01

    We fabricated polymeric micelles containing 5-fluorouracil (5-FU) or fluorescein using the amphiphilic block copolymer, poly-4-vinylpyridine-b-6-O-methacryloyl galactopyranose. Although the polymeric micelles were stable at pH 7.4, they readily decomposed at pH 5, resulting in near complete release of 5-FU. Uptake of polymeric micelles containing fluorescein by HepG2 and HCT116 cells was also investigated. With both cell types, strong fluorescence was observed after a 12-h incubation, but the fluorescence weakened after 24 h of incubation. The fluorescein incorporated into the polymeric micelles was released into acidic organelles (endosome and/or lysosome), from which it diffused throughout the cell. The cytotoxicity of polymeric micelles containing 5-FU was evaluated against HepG2 cells using a CCK-8 assay. The results suggest that polymeric micelles containing 5-FU are more cytotoxic to HepG2 cells than free 5-FU. PMID:26133065

  1. Synthesis and characterization of poly(D,L-lactide)-poly(ethylene glycol) multiblock poly(ether-ester-urethane)s

    NASA Astrophysics Data System (ADS)

    Haw, Tan Ching; Ahmad, Azizan; Anuar, Farah Hannan

    2015-09-01

    In this study, poly(D,L-lactide)-poly(ethylene glycol) multiblock poly(ether-ester-urethane)s was synthesized in the framework of environmental friendly products to meet the need for highly flexible polymers. Triblock copolymer with poly(ethylene glycol) as center block and poly(D,L-lactide) as side block were first synthesized by ring-opening polymerization of D,L-lactide, followed by chain extension reaction of triblocks using hexamethylene diisocyanate (HMDI). NMR and infra-red spectroscopies were used to determine the molecular composition whereas XRD analysis revealed crystallinity behavior of synthesized multiblock copolymers.

  2. Effect of in situ synthesized Fe2O3 and Co3O4 nanoparticles on electroactive β phase crystallization and dielectric properties of poly(vinylidene fluoride) thin films.

    PubMed

    Thakur, Pradip; Kool, Arpan; Bagchi, Biswajoy; Das, Sukhen; Nandy, Papiya

    2015-01-14

    A simple and low cost in situ process has been developed to synthesize Fe2O3-Co3O4 nanoparticles (NPs) loaded poly(vinylidene fluoride) (PVDF) thin films. The electroactive β phase nucleation mechanism and the dielectric properties of the films have been investigated by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and using an LCR meter. Results confirmed that the electroactive β phase crystallization in the PVDF matrix is due to the fast nucleating or catalytic effect of the in situ NPs. Homogenous dispersion of in situ Fe2O3-Co3O4 NPs in the polymer matrix leads to strong interfacial interaction between the NPs and the polymer resulting in enhanced β phase nucleation in PVDF and a large dielectric constant of the thin films. The observed variation in the electroactive β phase nucleation by NPs (Fe2O3-Co3O4) and the dielectric properties of the thin films have been explained on the basis of surface charge, size, geometrical shape and extent of agglomeration of the NPs in the polymer matrix. PMID:25424552

  3. Palladium-catalyzed cascade cyclization of allylamine-tethered alkylidenecyclopropanes: facile access to iodine/difluoromethylene- and perfluoroalkyl-containing 1-benzazepine scaffolds.

    PubMed

    Yu, Liu-Zhu; Zhu, Zi-Zhong; Hu, Xu-Bo; Tang, Xiang-Ying; Shi, Min

    2016-05-01

    The unprecedented palladium-catalyzed cascade cyclization of allylamine-tethered alkylidenecyclopropanes with an ethyl difluoroiodoacetate or perfluoroalkylated reagent is developed, providing facile access to a variety of synthetically and medicinally valuable iodine/difluoromethylene- and perfluoroalkyl-containing 1-benzazepine frameworks. These reactions exhibited good yields and functional group tolerance via a radical mechanism. PMID:27109032

  4. Magnetic and dielectric properties of sulfonated (S) poly[(styrene)-(ethylene-co-butylene)]-styrene (SEBS) block copolymer/magnetic metal oxide nanocomposites synthesized via an in-situ precipitation method

    NASA Astrophysics Data System (ADS)

    Peddini, Sateesh Kumar

    Block copolymer/magnetic metal oxide nanocomposites were synthesized by growing metal oxide nanoparticles (cobalt ferrite, CoFe2O 4 and iron oxide, alpha-Fe2O3) in sulfonated (s) poly (styrene) (PS) block domains of sulfonated poly [(styrene)-(ethylene-co-butylene)-(styrene)] (SEBS) BCP preformed films via an in-situ precipitation method by dissolving the salts of respective metal chloride (s) in a suitable solvent that selectively swells the sPS regions. Inorganic uptake was determined using thermogravimetric analysis (TGA), and it was observed that none of the samples incorporated more than 5 wt % of the inorganic component. Dynamical mechanical analysis was used to observe the changes in the glass transition temperatures (T g) in both blocks of the BCP by plotting tan delta vs. temperature responses in tensile mode on all samples. The results showed that the T g of the sPS block domains increased with sulfonation level and further increased with the incorporation of both nanoparticles in the same blocks, indicating that growth of nanoparticles takes place only in sPS blocks. The crystalline structure of the nanoparticles was observed using wide angle X-ray diffractometry (WAXD), and it was determined that cobalt iron oxide nanoparticles in 20 mole % sulfonated SEBS exhibited an inverse spinel structure confirming the structure to be CoFe2O4. And with iron oxide nanoparticles in 10 mole % sulfonated SEBS exhibiting a hematite (alpha-Fe2O 3) phase. Transmission electron microscopy (TEM) was used to investigate the particle size and distribution of nanoparticles in sBCP matrices at all sulfonation levels. Select area electron diffraction in TEM was used to determine crystalline structures of individual nanoparticles to compare with the structure observed from WAXD. The changes in thickness of interfaces between the individual PS and EB block domains with increase in sulfonation of PS blocks were investigated semi-quantitatively using tapping mode atomic force

  5. Antiproliferative synergism of the allylamine SF 86-327 and ketoconazole on epimastigotes and amastigotes of Trypanosoma (Schizotrypanum) cruzi.

    PubMed Central

    Urbina, J A; Lazardi, K; Aguirre, T; Piras, M M; Piras, R

    1988-01-01

    We have investigated the growth-inhibitory effects of two ergosterol biosynthesis inhibitors, the dioxolane imidazole ketoconazole and the allylamine SF 86-327, alone and in combination, on the proliferative stages of Trypanosoma (Schizotrypanum) cruzi, the causative agent of Chagas' disease. Proliferation of epimastigotes in liver infusion-tryptose medium at 28 degrees C was immediately arrested by any of these drugs at greater than or equal to 3 x 10(-5) M; cell lysis occurred 24 h later. Below that concentration, SF 86-327 at concentrations down to 1 x 10(-6) M stopped growth after 48 h. In contrast, ketoconazole slowed cell growth only moderately, but proliferation finally stopped and cell lysis occurred after 120 h at 3 x 10(-6) M. Synergistic effects could be observed when the two drugs were used in combination: the concentration of SF 86-327 required to reduce the cell growth to 25% of controls in 144 h was reduced 33-fold in the presence of 1 x 10(-6) M ketoconazole, which by itself reduced growth only by 30%. Amastigotes, proliferating in Vero cells at 37 degrees C, were much more susceptible to both drugs, but ketoconazole was definitely a more potent antiparasitic agent than the allylamine in this system: whereas the concentration of SF 86-327 required to reduce the number of infected cells to 50% of controls was 1 x 10(-7) M and that required to completely eradicate the parasite was 3 x 10(-6) M, for ketoconazole these concentrations were 1 x 10(-10) M and 1 x 10(-8) M, respectively. Again, strong synergistic effects were observed when the drugs were used in combination: the concentration of SF 86-327 required to reduce the number of infected cells to 50% of controls was 100-fold lower in the presence of 10(-11) M ketoconazole, which by itself had no effects on amastigote proliferation. The parasite was completely eradicated when the drugs were used in combination at concentrations as low as 10(-9) M. Synergy of the antiproliferative effects of the

  6. Partial hydrophilic modification of biaxially oriented polypropylene film by an atmospheric pressure plasma jet with the allylamine monomer

    NASA Astrophysics Data System (ADS)

    Chen, W. X.; Yu, J. S.; Hu, W.; Chen, G. L.

    2016-11-01

    In this paper, the partial modification of the biaxially oriented polypropylene (BOPP) film for potential biological and packaging applications was achieved via hydrophilic modification using atmospheric pressure plasma jet (APPJ). In the APPJ system, the allylamine (ALA) monomer was polymerized on the BOPP surface by either the Ar/O2 or the He/O2 plasma. The results showed that plasmatic modification created many micro/nano sized holes on the BOPP film, which increased the surface roughness dramatically and the increased roughness enhanced the combining intensity between the BOPP film and the ALA polymer. However, such a plasmatic modification increased the water vapor permeability. The FTIR and XPS characterizations showed that the amine groups were grafted onto the BOPP film, and the contact angle of the BOPP film decreases from 98.5° to 8°. Compared with the BOPP films treated by the Ar or He plasma, the barrier property of the modified BOPP film increased significantly when the ALA polymer was incorporated. The bio-affinity/toxicity of ALA polymer was illustrated by the attachment of the cultured SMMC-7721 hepatoma cells on the modified BOPP film. The significant enhancement in the cell density indicated that modified BOPP film was highly bio-compatible and non-toxic, especially treated with the Ar/O2/ALA plasma.

  7. Immobilization of DNA aptamers via plasma polymerized allylamine film to construct an endothelial progenitor cell-capture surface.

    PubMed

    Qi, Pengkai; Yan, Wei; Yang, Ying; Li, Yalong; Fan, Yi; Chen, Junying; Yang, Zhilu; Tu, Qiufen; Huang, Nan

    2015-02-01

    The endothelial progenitor cells (EPCs) capture stent has drawn increasing attentions and become one of the most promising concepts for the next generation vascular stent. In this regard, it is of great significance to immobilize a molecule with the ability to bind EPC for rapid in vivo endothelialization with high specificity. In this work, a facile two-step method aimed at constructing a coating with specific EPC capturing aptamers is reported. The processes involves as the first-step deposition of plasma polymerized allylamine (PPAam) on a substrate to introduce amine groups, followed by the electrostatic adsorption of a 34 bases single strand DNA sequence to the PPAam surface as a second step (PPAam-DNA). Grazing incidence attenuated total reflection Fourier transform infrared spectroscopy (GATR-FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed the successful immobilization of the aptamers. Quartz crystal microbalance with dissipation (QCM-D) real time monitoring result shows that about 175 ng/cm(2) aptamers were conjugated onto the PPAam surface. The interactions between the modified surfaces and human umbilical vein endothelial cells (ECs), smooth muscle cells (SMCs), and murine induced EPCs derived from mesenchymal stem cells (MSCs) were also investigated. It was demonstrated that PPAam-DNA samples could capture more EPCs, and present a cellular friendly surface for the proliferation of both EPCs and ECs but no effect on the hyperplasia of SMCs. Also, the co-culture results of 3 types of cells confirmed that the aptamer could specifically bond EPCs rather than ECs and SMCs, suggesting the competitive adhesion advantage of EPCs to ECs and SMCs. These data demonstrate that the EPC aptamer has large potential for designing an EPC captured stent and other vascular grafts with targeted in situ endothelialization. PMID:25575347

  8. Allylamine type xanthone antimycotics.

    PubMed

    Salmoiraghi, I; Rossi, M; Valenti, P; Da Re, P

    1998-06-01

    A number of xanthone derivatives bearing the basic chain of naftifine and butenafine antimycotics in 1, 2, 3, and 4 nuclear positions are described. The in vitro antifungal activity against representative strains of molds and yeasts is reported. Only butenafine xanthone analogues show significant activity against Cryptococcus neoformans, in particular the regioisomer 4d (1.5 micrograms/ml). PMID:9713256

  9. Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes

    PubMed Central

    Yang, Gesheng; Pastorino, Laura

    2016-01-01

    Summary The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA)n stereocomplex and the cores with and without the polymeric (PSS/PAH)n/PLL multilayer precursor (PEM). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) were used to characterize the chemical composition and molecular weight of poly(lactic acid) polymers. Both multilayer structures, with and without polymeric precursor, were firstly fabricated and characterized on planar supports. A quartz crystal microbalance (QCM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and ellipsometry were used to evaluate the thickness and mass of the multilayers. Then, hollow, spherical microcapsules were obtained by the removal of the CaCO3 sacrificial template. The chemical composition of the obtained microcapsules was confirmed by differential scanning calorimetry (DSC) and wide X-ray diffraction (WXRD) analyses. The microcapsule morphology was evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The experimental results confirm the successful fabrication of this innovative system, and its full biocompatibility makes it worthy of further characterization as a promising drug carrier for sustained release. PMID:26925356

  10. Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes.

    PubMed

    Dellacasa, Elena; Zhao, Li; Yang, Gesheng; Pastorino, Laura; Sukhorukov, Gleb B

    2016-01-01

    The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA) n stereocomplex and the cores with and without the polymeric (PSS/PAH) n /PLL multilayer precursor (PEM). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) were used to characterize the chemical composition and molecular weight of poly(lactic acid) polymers. Both multilayer structures, with and without polymeric precursor, were firstly fabricated and characterized on planar supports. A quartz crystal microbalance (QCM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and ellipsometry were used to evaluate the thickness and mass of the multilayers. Then, hollow, spherical microcapsules were obtained by the removal of the CaCO3 sacrificial template. The chemical composition of the obtained microcapsules was confirmed by differential scanning calorimetry (DSC) and wide X-ray diffraction (WXRD) analyses. The microcapsule morphology was evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The experimental results confirm the successful fabrication of this innovative system, and its full biocompatibility makes it worthy of further characterization as a promising drug carrier for sustained release. PMID:26925356

  11. Chemically crosslinked nanogels of PEGylated poly ethyleneimine (l-histidine substituted) synthesized via metal ion coordinated self-assembly for delivery of methotrexate: Cytocompatibility, cellular delivery and antitumor activity in resistant cells.

    PubMed

    Abolmaali, Samira Sadat; Tamaddon, Ali Mohammad; Mohammadi, Samaneh; Amoozgar, Zohreh; Dinarvand, Rasoul

    2016-05-01

    Self-assembled nanogels were engineered by forming Zn(2+)-coordinated micellar templates of PEGylated poly ethyleneimine (PEG-g-PEI), chemical crosslinking and subsequent removal of the metal ion. Creation of stable micellar templates is a crucial step for preparing the nanogels. To this aim, imidazole moieties were introduced to the polymer by Fmoc-l-histidine using carbodiimide chemistry. It was hypothesized the nanogels loaded with methotrexate (MTX), a chemotherapeutic agent, circumvent impaired carrier activity in HepG2 cells (MTX-resistant hepatocellular carcinoma). So, the nanogels were post-loaded with MTX and characterized by (1)H-NMR, FTIR, dynamic light scattering-zeta potential, atomic force microscopy, and drug release experiments. Cellular uptake and the antitumor activity of MTX-loaded nanogels were investigated by flow cytometry and MTT assay. Discrete, spherical and uniform nanogels, with sizes about 77-83 nm and a relatively high drug loading (54 ± 4% w/w), showed a low polydispersity and neutral surface charges. The MTX-loaded nanogels, unlike empty nanogels, lowered viability of HepG2 cells; the nanogels demonstrated cell-cycle arrest and apoptosis comparably higher than MTX as free drug that was shown to be through i) cellular uptake of the nanogels by clathrin-mediated transport and ii) endosomolytic activity of the nanogels in HepG2 cells. These findings indicate the potential antitumor application of this preparation, which has to be investigated in-vivo. PMID:26952497

  12. Syntheses and studies of acetylenic polymers

    SciTech Connect

    Yiwei, Ding

    1994-03-03

    Based on new diiodo aryl compounds a series of novel soluble polymers, poly(2,5-dialkoxy-1,4-phenyleneethynylene)s (PPE polymers) were synthesized using palladium-catalysis. The molecular weights (MW) range from 8,000 to 40,000. Properties such as absorption, fluorescence, and conductivity were studied. A PPE polymer with butoxy side chain exhibits a weak electrical conductivity ({sigma} = 10{sup {minus}3} S/cm) after doping with AsF{sub 5}. Absorption spectra in THF solution at room temperature (RT) show a maximum at 440 nm. However, absorption spectra of PPE polymers in the film state at (RT) show a maximum at 480 nm. PPE polymer-based light emitting diode (LED) devices have been prepared; greenish light from these LED devices can be observed. Poly(ethynylene-p-arylene-ethynylene-silylene)s were synthesized through the same palladium-catalyzed polymerization; MWs are between 6,000 and 82,000. Absorption and fluorescence were studied. Some of these polymers exhibit thermotropic liquid crystalline properties. In addition, nonlinear optical properties were briefly examined. Poly(silylene-ethynylene) homopolymers as well as alternating copolymers were synthesized through a novel palladium-catalyzed polymerization; MWs range from 56 {times} 10{sup 3} to 5.3 {times} 10{sup 3}. Thermal stability of these was also investigated; char yields range from 56 to 83%. One of these polymers exhibits thermotropic liquid crystalline properties.

  13. Azide functionalized poly(3-hexylthiophene) and method of forming same

    DOEpatents

    Qin, Yang; Grubbs, Robert B; Park, Young Suk

    2014-03-25

    The invention relates azide functionalized poly(3-hexylthiophene)s. Various azide functionalized poly(3-hexylthiophene)s and intermediates are disclosed and described, as well as method for making novel monomers that are synthesized and transformed into P3HT-N.sub.mp for use as organic conducting polymers in organic photovoltaic devices.

  14. Portable Speech Synthesizer

    NASA Technical Reports Server (NTRS)

    Leibfritz, Gilbert H.; Larson, Howard K.

    1987-01-01

    Compact speech synthesizer useful traveling companion to speech-handicapped. User simply enters statement on board, and synthesizer converts statement into spoken words. Battery-powered and housed in briefcase, easily carried on trips. Unit used on telephones and face-to-face communication. Synthesizer consists of micro-computer with memory-expansion module, speech-synthesizer circuit, batteries, recharger, dc-to-dc converter, and telephone amplifier. Components, commercially available, fit neatly in 17-by 13-by 5-in. briefcase. Weighs about 20 lb (9 kg) and operates and recharges from ac receptable.

  15. Polyelectrolyte multilayer surface functionalization of poly(dimethylsiloxane) (PDMS) for reduction of yeast cell adhesion in microfluidic devices

    PubMed Central

    Schmolke, Hannah; Demming, Stefanie; Edlich, Astrid; Magdanz, Veronika; Büttgenbach, Stephanus; Franco-Lara, Ezequiel; Krull, Rainer; Klages, Claus-Peter

    2010-01-01

    Polyelectrolyte multilayers (PEMs) based on the combinations poly(diallyldimethylammonium chloride)∕poly(acrylic acid) (PDADMAC∕PAA) and poly(allylamine hydrochloride)∕PAA (PAH∕PAA) were adsorbed on poly(dimethylsiloxane) (PDMS) and tested for nonspecific surface attachment of hydrophobic yeast cells using a parallel plate flow chamber. A custom-made graft copolymer containing poly(ethylene glycol) (PEG) side chains (PAA-g-PEG) was additionally adsorbed on the PEMs as a terminal layer. A suitable PEM modification effectively decreased the adhesion strength of Saccharomyces cerevisiae DSM 2155 to the channel walls. However, a further decrease in initial cell attachment and adhesion strength was observed after adsorption of PAA-g-PEG copolymer onto PEMs from aqueous solution. The results demonstrate that a facile layer-by-layer surface functionalization from aqueous solutions can be successfully applied to reduce cell adhesion strength of S. cerevisiae by at least two orders of magnitude compared to bare PDMS. Therefore, this method is potentially suitable to promote planktonic growth inside capped PDMS-based microfluidic devices if the PEM deposition is completed by a dynamic flow-through process. PMID:21267092

  16. Ideal CO2/Light Gas Separation Performance of Poly(vinylimidazolium) Membranes and Poly(vinylimidazolium)-Ionic Liquid Composite Films

    SciTech Connect

    Carlisle, TK; Wiesenauer, EF; Nicodemus, GD; Gin, DL; Noble, RD

    2013-01-23

    Six vinyl-based, imidazolium room-temperature ionic liquid (RTIL) monomers were synthesized and photopolymerized to form dense poly(RTIL) membranes. The effect of polymer backbone (i.e., poly(ethylene), poly(styrene), and poly(acrylate)) and functional cationic substituent (e.g., alkyl, fluoroalkyl, oligo(ethylene glycol), and disiloxane) on ideal CO2/N-2 and CO2/CH4 membrane separation performance was investigated. The vinyl-based poly(RTIL)s were found to be generally less CO2-selective compared to analogous styrene- and acrylate-based poly(RTIL)s. The CO2 permeability of n-hexyl-(69 barrers) and disiloxane- (130 barrers) substituted vinyl-based poly(RTIL)s were found to be exceptionally larger than that of previously studied styrene and acrylate poly(RTIL)s. The CO2 selectivity of oligo(ethylene glycol)-functionalized vinyl poly(RTIL)s was enhanced, and the CO2 permeability was reduced when compared to the n-hexyl-substituted vinyl-based poly(RTIL). Nominal improvement in CO2/CH4 selectivity was observed upon fluorination of the n-hexyl vinyl-based poly(RTIL), with no observed change in CO2 permeability. However, rather dramatic improvements in both CO2 permeability and selectivity were observed upon blending 20 mol % RTIL (emim Tf2N) into the n-hexyl- and disiloxane-functionalized vinyl poly(RTIL)s to form solid liquid composite films.

  17. Uses of a Vinylpyridine Polymer in Undergraduate Organic Syntheses.

    ERIC Educational Resources Information Center

    Getman, Damon; And Others

    1984-01-01

    Presents a series of syntheses in which poly-4-vinylpyridine is substituted for pyridine or other tertiary amines, avoiding some of the safety problems associated with traditional reagents and providing a readily recoverable and recyclable reactant. Background information, procedures used, and results are included. (JN)

  18. Syntheses and insulin-like activity of phosphorylated galactose derivatives.

    PubMed

    Caro, H N; Martín-Lomas, M; Bernabé, M

    1993-02-24

    The syntheses of the poly-phosphorylated galactosides 6, 8, 10, 13, 16, and 20, isolated as sodium salts, have been performed. The non-phosphorylated disaccharide 17 and trisaccharide 21 have been prepared via glycosylation of the 2-(trimethylsilyl)ethyl galactosides 3 and 2, respectively, and subsequent complete deprotection. Preliminary insulin-like activity of the phosphorylated derivatives is reported. PMID:8458006

  19. Multiplexed chirp waveform synthesizer

    DOEpatents

    Dudley, Peter A.; Tise, Bert L.

    2003-09-02

    A synthesizer for generating a desired chirp signal has M parallel channels, where M is an integer greater than 1, each channel including a chirp waveform synthesizer generating at an output a portion of a digital representation of the desired chirp signal; and a multiplexer for multiplexing the M outputs to create a digital representation of the desired chirp signal. Preferably, each channel receives input information that is a function of information representing the desired chirp signal.

  20. PULSE SYNTHESIZING GENERATOR

    DOEpatents

    Kerns, Q.A.

    1963-08-01

    >An electronlc circuit for synthesizing electrical current pulses having very fast rise times includes several sinewave generators tuned to progressively higher harmonic frequencies with signal amplitudes and phases selectable according to the Fourier series of the waveform that is to be synthesized. Phase control is provided by periodically triggering the generators at precisely controlled times. The outputs of the generators are combined in a coaxial transmission line. Any frequency-dependent delays that occur in the transmission line can be readily compensated for so that the desired signal wave shape is obtained at the output of the line. (AEC)

  1. Wisdom, Intelligence & Creativity Synthesized

    ERIC Educational Resources Information Center

    Sternberg, Robert J.

    2009-01-01

    How is it that smart administrators who want to do a good job often find themselves in situations that degenerate into confrontation and, ultimately, termination? In this article, the author discusses why in terms of a model of leadership--which he refers to it as WICS, an acronym for wisdom, intelligence and creativity synthesized. He describes…

  2. Synthesized night vision goggle

    NASA Astrophysics Data System (ADS)

    Zhou, Haixian

    2000-06-01

    A Synthesized Night Vision Goggle that will be described int his paper is a new type of night vision goggle with multiple functions. It consists of three parts: main observing system, picture--superimposed system (or Cathode Ray Tube system) and Charge-Coupled Device system.

  3. Antifouling poly(β-peptoid)s.

    PubMed

    Lin, Shaohui; Zhang, Bo; Skoumal, Michael J; Ramunno, Brian; Li, Xiaopeng; Wesdemiotis, Chrys; Liu, Lingyun; Jia, Li

    2011-07-11

    A new type of polymer highly resistant to nonspecific protein adsorption is reported. Poly(N-methyl-β-alanine) (PMeA) and poly(N-ethyl-β-alanine) (PEtA) synthesized via cobalt-catalyzed carbonylative polymerization of N-methylaziridine and N-ethylaziridine were end-functionalized with thiol groups and grafted onto Au surfaces. Protein adsorption was studied by the surface plasmon resonance (SPR) method. The amounts of representative single proteins adsorbed onto the PMeA- and PEtA-grafted surfaces were below the detection limit of SPR at the pg/mm(2) level. After exposure to full blood plasma and serum for 10 min, protein adsorption was at the level of ∼ 100 pg/mm(2), similar to the level of protein adsorption on poly(ethylene glycol) surfaces subjected to identical conditions. These poly(β-peptoid)s therefore provide excellent protein resistance comparable to the best antifouling materials known to date. The strong proton-accepting ability when forming hydrogen bonds is suggested to be an important attribute for these poly(β-peptoid)s as well as other poly(tertiary amide)s as antifouling materials. PMID:21585194

  4. Preparation of poly (styrene)-b-poly (acrylic acid)/γ-Fe 2O 3 composites

    NASA Astrophysics Data System (ADS)

    Zhang, L. D.; Liu, W. L.; Xiao, C. L.; Yao, J. S.; Fan, Z. P.; Sun, X. L.; Zhang, X.; Wang, L.; Wang, X. Q.

    2011-12-01

    The use of a block copolymer, poly (styrene)-b-poly (acrylic acid) (PS-b-PAA) to prepare a magnetic nanocomposite was investigated. Poly (styrene)-poly (t-butyl acrylate) block copolymer, being synthesized by atom transfer radical polymerization, was hydrolyzed with hydrochloric acid for obtaining PS-b-PAA. The obtained PS-b-PAA was then compounded with the modified γ-Fe2O3, and subsequently the magnetic nanocomposite was achieved. The products were characterized by 1H NMR, FTIR, gel permeation chromatography, thermogravimetric analysis, transmission electron microscopy and vibrating sample magnetometer. The results showed that the nanocomposites exhibited soft magnetism, with the mean diameter of 100 nm approximately.

  5. Total Syntheses of Perenniporides.

    PubMed

    Morita, Masao; Ohmori, Ken; Suzuki, Keisuke

    2015-11-20

    The total syntheses of perenniporide A (1) and related compounds have been achieved. Starting from 1,3,5-trifluorobenzene (9), difluorodienone 6 was obtained by oxidative dearomatization, which served as a platform for the high-pressure cycloaddition and for the introduction of the C3-methoxy group. The synthesis allowed access to the natural congeners 2 and 3, enabling assignment of the absolute structures of these natural products. PMID:26555442

  6. Studies on protein poly(ADP-ribosylation) using high resolution gel electrophoresis.

    PubMed

    Boulikas, T

    1990-08-25

    Analysis of poly(ADP-ribose) synthesized in cellular lysates or in isolated nuclei on 100-cm-long thin gels of 20% polyacrylamide, 2.5 M urea permits determination of the exact size of poly(ADP-ribose) molecules using labeled oligonucleotides as molecular weight markers. The size and concentration of poly(ADP-ribose) molecules increase at time intervals during its synthesis. Differences in the concentration of poly(ADP-ribose) size classes among cell lines are also shown. Inhibition of poly(ADP-ribose) degradation by ethacridine that directly interacts with the polymer and inhibits its hydrolysis by poly(ADP-ribose) glycohydrolase shows a dramatic increase in both polymer size and concentration. Use of alkaline conditions for the hydrolysis of poly(ADP-ribose)-protein linkages reveals a specific shortening of all size classes of poly(ADP-ribose) compared with its size in preparations obtained by extensive digestion of nuclei with nucleases, RNases, and proteases. PMID:2167322

  7. Synthesizing folded band chaos.

    PubMed

    Corron, Ned J; Hayes, Scott T; Pethel, Shawn D; Blakely, Jonathan N

    2007-04-01

    A randomly driven linear filter that synthesizes Lorenz-like, reverse-time chaos is shown also to produce Rössler-like folded band wave forms when driven using a different encoding of the random source. The relationship between the topological entropy of the random source, dissipation in the linear filter, and the positive Lyapunov exponent for the reverse-time wave form is exposed. The two drive encodings are viewed as grammar restrictions on a more general encoding that produces a chaotic superset encompassing both the Lorenz butterfly and Rössler folded band paradigms of nonlinear dynamics. PMID:17500950

  8. SYNTH: A spectrum synthesizer

    NASA Astrophysics Data System (ADS)

    Hensley, W. K.; McKinnon, A. D.; Miley, H. S.; Panisko, M. E.; Savard, R. M.

    1993-10-01

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma ray spectroscopy experiments. The code, dubbed SYNTH, allows a user to specify physical characteristics of a gamma ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the presence of absorbers, the type and size of the detector, and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function versus energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results are presented.

  9. Programmable electronic synthesized capacitance

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L. (Inventor)

    1987-01-01

    A predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.

  10. Solvent resistant microfluidic DNA synthesizer.

    PubMed

    Huang, Yanyi; Castrataro, Piero; Lee, Cheng-Chung; Quake, Stephen R

    2007-01-01

    We fabricated a microfluidic DNA synthesizer out of perfluoropolyether (PFPE), an elastomer with excellent chemical compatibility which makes it possible to perform organic chemical reactions, and synthesized 20-mer oligonucleotides on chip. PMID:17180201

  11. Method for synthesizing HMX

    SciTech Connect

    McGuire, R.R.; Coon, C.L.; Harrar, J.E.; Pearson, R.K.

    1984-02-21

    A method and apparatus for electrochemically synthesizing N/sub 2/O/sub 5/ includes oxidizing a solution of N/sub 2/O/sub 4//HNO/sub 3/ at an anode, while maintaining a controlled potential between the N/sub 2/O/sub 4//HNO/sub 3/ solution and the anode. A potential of about 1.35 to 2.0 V vs. SCE is preferred, while a potential of about 1.80 V vs. SCE is most preferred. Thereafter, the N/sub 2/O/sub 5/ is reacted with either 1.5-diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DADN) or 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) to form cyclotetramethylenetetraamine (HMX).

  12. Method for synthesizing HMX

    DOEpatents

    McGuire, Raymond R.; Coon, Clifford L.; Harrar, Jackson E.; Pearson, Richard K.

    1984-01-01

    A method and apparatus for electrochemically synthesizing N.sub.2 O.sub.5 cludes oxidizing a solution of N.sub.2 O.sub.4 /HNO.sub.3 at an anode, while maintaining a controlled potential between the N.sub.2 O.sub.4 /HNO.sub.3 solution and the anode. A potential of about 1.35 to 2.0 V vs. SCE is preferred, while a potential of about 1.80 V vs. SCE is most preferred. Thereafter, the N.sub.2 O.sub.5 is reacted with either 1.5-diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DADN) or 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) to form cyclotetramethylenetetraamine (HMX).

  13. Poly(oligonucleotide)

    PubMed Central

    2015-01-01

    Here we report the preparation of poly(oligonucleotide) brush polymers and amphiphilic brush copolymers from nucleic acid monomers via graft-through polymerization. We describe the polymerization of PNA-norbornyl monomers to yield poly-PNA (poly(peptide nucleic acid)) via ring-opening metathesis polymerization (ROMP) with the initiator, (IMesH2)(C5H5N)2(Cl)2RuCHPh.1 In addition, we present the preparation of poly-PNA nanoparticles from amphiphilic block copolymers and describe their hybridization to a complementary single-stranded DNA (ssDNA) oligonucleotide. PMID:25077676

  14. Synthesis, characterization and nanocomposite formation of poly(glycerol succinate-co-maleate) with cellulose nanowhiskers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel biodegradable polymer based on glycerol, succinic anhydride and maleic anhydride, poly(glycerol succinate-co-maleate), poly(GlySAMA), was synthesized by melt polycondensation and tested as a matrix for composites with cellulose nanowhiskers. This glycerol-based polymer is thermally stable as...

  15. Controlled Degradation of Poly(Ethyl Cyanoacrylate-Co-Methyl Methacrylate)(PECA-Co-PMMA) Copolymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper describes a method for modifying poly(ethyl cyanoacrylate) in order to control the degradation and the stability as well as the glass transition temperatures. Copolymers of poly(ethyl cyanoacrylate-co-methyl methacrylate) (PECA-co-PMMA) with various compositions were synthesized by free ...

  16. Doclet To Synthesize UML

    NASA Technical Reports Server (NTRS)

    Barry, Matthew R.; Osborne, Richard N.

    2005-01-01

    The RoseDoclet computer program extends the capability of Java doclet software to automatically synthesize Unified Modeling Language (UML) content from Java language source code. [Doclets are Java-language programs that use the doclet application programming interface (API) to specify the content and format of the output of Javadoc. Javadoc is a program, originally designed to generate API documentation from Java source code, now also useful as an extensible engine for processing Java source code.] RoseDoclet takes advantage of Javadoc comments and tags already in the source code to produce a UML model of that code. RoseDoclet applies the doclet API to create a doclet passed to Javadoc. The Javadoc engine applies the doclet to the source code, emitting the output format specified by the doclet. RoseDoclet emits a Rose model file and populates it with fully documented packages, classes, methods, variables, and class diagrams identified in the source code. The way in which UML models are generated can be controlled by use of new Javadoc comment tags that RoseDoclet provides. The advantage of using RoseDoclet is that Javadoc documentation becomes leveraged for two purposes: documenting the as-built API and keeping the design documentation up to date.

  17. Synthesizing Exoplanet Demographics

    NASA Astrophysics Data System (ADS)

    Clanton, Christian

    2016-01-01

    The discovery of thousands of exoplanets has revealed a large diversity of systems, the majority of which look nothing like our own. On the theoretical side, we are able to make ab initio calculations that make predictions about the properties of exoplanets. However, in order to link these predictions with observations, we must construct a statistical census of exoplanet demographics over as broad a range of parameters as possible. Current constraints on exoplanet demographics are typically constructed using the results of individual surveys using a single detection technique, and thus are incomplete. The only way to derive a statistically-complete census that samples a wide region of exoplanet parameter space is to synthesize the results from surveys employing all of the different discovery methods at our disposal. I present the first studies to demonstrate that this is actually possible, and describe a (mostly) de-biased exoplanet census that is constructed from the synthesis of results from microlensing, radial velocity, and direct imaging surveys. I will also discuss future work that will include the results of transit surveys (in particular, Kepler discoveries) to complete the census of exoplanets in our Galaxy, and describe the application of this census to develop the most comprehensive, observationally-constrained models of planet formation and evolution that have been derived to date.

  18. Synthesis and degradation behavior of poly(ethyl cyanoacrylate)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(ethyl cyanoacrylate) was synthesized using N, N'-dimethyl-p-toulidine (DMPT) as an initiator through anionic/zwitterionic pathway. The degradability and the degradation mechanism of the prepared polymers were carefully examined from various points of views. It was found that the polymers were...

  19. Synthesis of poly(aminoamides)via enzymatic means

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(aminoamides) constitute a subclass of polyamides that are water-soluble and useful for several applications. Commercially they are made via chemical reaction pathways. A review is made in this work of the enzymatic approaches towards their syntheses. Lipases and esterases have been found to ...

  20. Antibacterial activity of poly(vinyl alcohol)-b-poly(acrylonitrile) based micelles loaded with silver nanoparticles.

    PubMed

    Bryaskova, Rayna; Pencheva, Daniela; Kyulavska, Mariya; Bozukova, Dimitriya; Debuigne, Antoine; Detrembleur, Christophe

    2010-04-15

    A new amphiphilic poly(vinyl alcohol)-b-poly(acrylonitrile) (PVOH-b-PAN) copolymer obtained by selective hydrolysis of well-defined poly(vinyl acetate)-b-poly(acrylonitrile) copolymer synthesized by cobalt mediated radical polymerization was used for the preparation of PVOH-b-PAN based micelles with embedded silver nanoparticles. The successful formation of silver loaded micelles has been confirmed by UV-vis, DLS and TEM analysis and their antibacterial activity against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa) and spore solution of Bacillus subtilis (B. subtilis) has been studied. PVOH-b-PAN based micelles with embedded silver nanoparticles showed a strong bactericidal effect against E. coli, S. aureus and P. aeruginosa and the minimum bactericidal concentration for each system (MBC) has been determined. PMID:20074742

  1. Synthesis and surface immobilization of antibacterial hybrid silver-poly(l-lactide) nanoparticles

    NASA Astrophysics Data System (ADS)

    Taheri, Shima; Baier, Grit; Majewski, Peter; Barton, Mary; Förch, Renate; Landfester, Katharina; Vasilev, Krasimir

    2014-08-01

    Infections associated with medical devices are a substantial healthcare problem. Consequently, there has been increasing research and technological efforts directed toward the development of coatings that are capable of preventing bacterial colonization of the device surface. Herein, we report on novel hybrid silver loaded poly(L-lactic acid) nanoparticles (PLLA-AgNPs) with narrowly distributed sizes (17 ± 3 nm) prepared using a combination of solvent evaporation and mini-emulsion technology. These particles were then immobilized onto solid surfaces premodified with a thin layer of allylamine plasma polymer (AApp). The antibacterial efficacy of the PLLA-AgNPs nanoparticles was studied in vitro against both gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria. The minimal inhibitory concentration values against Staphylococcus epidermidis and Escherichia coli were 0.610 and 1.156 μg · mL-1, respectively. The capacity of the prepared coatings to prevent bacterial surface colonization was assessed in the presence of Staphylococcus epidermidis, which is a strong biofilm former that causes substantial problems with medical device associated infections. The level of inhibition of bacterial growth was 98%. The substrate independent nature and the high antibacterial efficacy of coatings presented in this study may offer new alternatives for antibacterial coatings for medical devices.

  2. Microwave-Assisted Azidation Reaction for Rapid Synthesis of Poly(3,3ʹ-Bisazidomethyl Oxetane)

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Li, Jie; Luo, Yun-Jun; Zhai, Bin

    2016-04-01

    We successfully designed and developed a new strategy for synthesizing an energetic material, poly(3,3ʹ-bisazidomethyl oxetane) (PBAMO), by microwave assistance, which dramatically shortened the reaction time and improved the safety of the synthetic process.

  3. Electrospun nanofibers of polyCD/PMAA polymers and their potential application as drug delivery system.

    PubMed

    Oliveira, Michele F; Suarez, Diego; Rocha, Júlio Cézar Barbosa; de Carvalho Teixeira, Alvaro Vianna Novaes; Cortés, Maria E; De Sousa, Frederico B; Sinisterra, Rubén D

    2015-09-01

    Herein, we used an electrospinning process to develop highly efficacious and hydrophobic coaxial nanofibers based on poly-cyclodextrin (polyCD) associated with poly(methacrylic acid) (PMAA) that combines polymeric and supramolecular features for modulating the release of the hydrophilic drug, propranolol hydrochloride (PROP). For this purpose, polyCD was synthesized and characterized, and its biocompatibility was assessed using fibroblast cytotoxicity tests. Moreover, the interactions between the guest PROP molecule and both polyCD and βCD were found to be spontaneous. Subsequently, PROP was encapsulated in uniaxial and coaxial polyCD/PMAA nanofibers. A lower PROP burst effect (reduction of approximately 50%) and higher modulation were observed from the coaxial than from the uniaxial fibers. Thus, the coaxial nanofibers could potentially be a useful strategy for developing a controlled release system for hydrophilic molecules. PMID:26046289

  4. Immobilization of poly(acrylamide) brushes onto poly(caprolactone) surface by combining ATRP and "click" chemistry: Synthesis, characterization and evaluation of protein adhesion

    NASA Astrophysics Data System (ADS)

    Ma, Yuhao; Bian, Xinxiu; He, Liu; Cai, Mengtan; Xie, Xiaoxiong; Luo, Xianglin

    2015-02-01

    Developments of poly(caprolactone) in blood-contacting applications are often restricted due to its intrinsic hydrophobicity. One common way to improve its hemocompatibility is to attach hydrophilic polymers. Here we developed a non-destructive method to graft hydrophilic poly(acrylamide) (PAAm) onto poly(caprolactone) (PCL) surface. In this strategy, azido-ended PCL with low molecular weights was synthesized and blended with PCL to create a surface with "clickable" property. Alkyne-ended poly(acrylamide)s with controlled chain lengths were then synthesized by atom transfer radical polymerization (ATRP), and finally were immobilized onto PCL surface by "click" reaction. The occurrence of immobilization was verified qualitatively by water contact angle measurement and quantitatively by X-ray photoelectron spectroscopy (XPS). The PAAm grafted surface exhibited fouling resistant properties, as demonstrated by reduced bovine serum albumin (BSA) and fibrinogen (Fg) adhesion.

  5. Frequency synthesizers for telemetry receivers

    NASA Astrophysics Data System (ADS)

    Stirling, Ronald C.

    1990-07-01

    The design of a frequency synthesizer is presented for telemetry receivers. The synthesizer contains two phase-locked loops, each with a programmable frequency counter, and incorporates fractional frequency synthesis but does not use a phase accumulator. The selected receiver design has a variable reference loop operating as a part of the output loop. Within the synthesizer, a single VTO generates the output frequency that is voltage-tunable from 375-656 MHz. The single-sideband phase noise is measured with an HP 8566B spectrum analyzer, and the receiver's bit error rate (BER) is measured with a carrier frequency of 250 MHz, synthesized LO at 410 MHz, and the conditions of BPSK, NRZ-L, and 2.3 kHz bit rate. The phase noise measurement limits and the BER performance data are presented in tabular form.

  6. Poly(ester urethane)s consisting of poly[(R)-3-hydroxybutyrate] and poly(ethylene glycol) as candidate biomaterials: characterization and mechanical property study.

    PubMed

    Li, Xu; Loh, Xian Jun; Wang, Ke; He, Chaobin; Li, Jun

    2005-01-01

    Poly(ester urethane)s with poly[(R)-3-hydroxybutyrate] (PHB) as the hard and hydrophobic segment and poly(ethylene glycol) (PEG) as the soft and hydrophilic segment were synthesized from telechelic hydroxylated PHB (PHB-diol) and PEG using 1,6-hexamethylene diisocyanate as a nontoxic coupling reagent. Their chemical structures and molecular characteristics were studied by gel permeation chromatography, 1H NMR, and Fourier transform infrared spectroscopy. Results of differential scanning calorimetry and X-ray diffraction indicated that the PHB segment and PEG segment in the poly(ester urethane)s formed separate crystalline phases with lower crystallinity and a lower melting point than those of their corresponding precursors, except no PHB crystalline phase was observed in those with a relatively low PHB fraction. Thermogravimetric analysis showed that the poly(ester urethane)s had better thermal stability than their precursors. The segment compositions were calculated from the two-step thermal decomposition profiles, which were in good agreement with those obtained from 1H NMR. Water contact angle measurement and water swelling analysis revealed that both surface hydrophilicity and bulk hydrophilicity of the poly(ester urethane)s were enhanced by incorporating the PEG segment into PHB polymer chains. The mechanical properties of the poly(ester urethane)s were also assessed by tensile strength measurement. It was found that the poly(ester urethane)s were ductile, while natural source PHB is brittle. Young's modulus and the stress at break increased with increasing PHB segment length or PEG segment length, whereas the strain at break increased with increasing PEG segment length or decreasing PHB segment length. PMID:16153114

  7. Copper nanocoils synthesized through solvothermal method.

    PubMed

    Liu, Yanjuan; Liu, Xiaowei; Zhan, Yongjie; Fan, Haiming; Lu, Yang

    2015-01-01

    Recently helical nanostructures such as nanosprings and nanocoils have drawn great interests in nanotechnology, due to their unique morphologies and physical properties, and they may be potential building blocks in sorts of electromechanical, magnetic, photoelectronic and plasmonic devices at micro/nanoscales. In this report, multi-turns copper nanocoils were synthesized through a modified solvothermal method, in which the mixture of water and N-methyl-2-pyrrolidone (NMP) were selected as reaction medium and copolymer poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA 64E) as reductant. In the liquid solution, nanosprings could be formed from relaxed nanocoils and demonstrated high elasticity. These nanocoils and nanosprings are of single crystalline structure, with the characteristics wire diameters ranging from tens to a few hundreds of nanometers and the ring/coil diameters mostly ~10-35 microns. Their growth and deformation mechanisms were then investigated and discussed along with that of previously reported single-turn copper nanorings. This work could be of importance for researchers working on synthesis and applications of novel 1-D helical nanomaterials and their functional devices. PMID:26607386

  8. Copper nanocoils synthesized through solvothermal method

    NASA Astrophysics Data System (ADS)

    Liu, Yanjuan; Liu, Xiaowei; Zhan, Yongjie; Fan, Haiming; Lu, Yang

    2015-11-01

    Recently helical nanostructures such as nanosprings and nanocoils have drawn great interests in nanotechnology, due to their unique morphologies and physical properties, and they may be potential building blocks in sorts of electromechanical, magnetic, photoelectronic and plasmonic devices at micro/nanoscales. In this report, multi-turns copper nanocoils were synthesized through a modified solvothermal method, in which the mixture of water and N-methyl-2-pyrrolidone (NMP) were selected as reaction medium and copolymer poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA 64E) as reductant. In the liquid solution, nanosprings could be formed from relaxed nanocoils and demonstrated high elasticity. These nanocoils and nanosprings are of single crystalline structure, with the characteristics wire diameters ranging from tens to a few hundreds of nanometers and the ring/coil diameters mostly ~10-35 microns. Their growth and deformation mechanisms were then investigated and discussed along with that of previously reported single-turn copper nanorings. This work could be of importance for researchers working on synthesis and applications of novel 1-D helical nanomaterials and their functional devices.

  9. Copper nanocoils synthesized through solvothermal method

    PubMed Central

    Liu, Yanjuan; Liu, Xiaowei; Zhan, Yongjie; Fan, Haiming; Lu, Yang

    2015-01-01

    Recently helical nanostructures such as nanosprings and nanocoils have drawn great interests in nanotechnology, due to their unique morphologies and physical properties, and they may be potential building blocks in sorts of electromechanical, magnetic, photoelectronic and plasmonic devices at micro/nanoscales. In this report, multi-turns copper nanocoils were synthesized through a modified solvothermal method, in which the mixture of water and N-methyl-2-pyrrolidone (NMP) were selected as reaction medium and copolymer poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA 64E) as reductant. In the liquid solution, nanosprings could be formed from relaxed nanocoils and demonstrated high elasticity. These nanocoils and nanosprings are of single crystalline structure, with the characteristics wire diameters ranging from tens to a few hundreds of nanometers and the ring/coil diameters mostly ~10–35 microns. Their growth and deformation mechanisms were then investigated and discussed along with that of previously reported single-turn copper nanorings. This work could be of importance for researchers working on synthesis and applications of novel 1-D helical nanomaterials and their functional devices. PMID:26607386

  10. RAMESES publication standards: realist syntheses

    PubMed Central

    2013-01-01

    Background There is growing interest in realist synthesis as an alternative systematic review method. This approach offers the potential to expand the knowledge base in policy-relevant areas - for example, by explaining the success, failure or mixed fortunes of complex interventions. No previous publication standards exist for reporting realist syntheses. This standard was developed as part of the RAMESES (Realist And MEta-narrative Evidence Syntheses: Evolving Standards) project. The project's aim is to produce preliminary publication standards for realist systematic reviews. Methods We (a) collated and summarized existing literature on the principles of good practice in realist syntheses; (b) considered the extent to which these principles had been followed by published syntheses, thereby identifying how rigor may be lost and how existing methods could be improved; (c) used a three-round online Delphi method with an interdisciplinary panel of national and international experts in evidence synthesis, realist research, policy and/or publishing to produce and iteratively refine a draft set of methodological steps and publication standards; (d) provided real-time support to ongoing realist syntheses and the open-access RAMESES online discussion list so as to capture problems and questions as they arose; and (e) synthesized expert input, evidence syntheses and real-time problem analysis into a definitive set of standards. Results We identified 35 published realist syntheses, provided real-time support to 9 on-going syntheses and captured questions raised in the RAMESES discussion list. Through analysis and discussion within the project team, we summarized the published literature and common questions and challenges into briefing materials for the Delphi panel, comprising 37 members. Within three rounds this panel had reached consensus on 19 key publication standards, with an overall response rate of 91%. Conclusion This project used multiple sources to develop and

  11. Strong nonlinear photonic responses from microbiologically synthesized tellurium nanocomposites

    USGS Publications Warehouse

    Liao, K.-S.; Wang, Jingyuan; Dias, S.; Dewald, J.; Alley, N.J.; Baesman, S.M.; Oremland, R.S.; Blau, W.J.; Curran, S.A.

    2010-01-01

    A new class of nanomaterials, namely microbiologically-formed nanorods composed of elemental tellurium [Te(0)] that forms unusual nanocomposites when combined with poly(m-phenylenevinylene-co-2,5-dioctoxy-phenylenevinylene) (PmPV) is described. These bio-nanocomposites exhibit excellent broadband optical limiting at 532 and 1064 nm. Nonlinear scattering, originating from the laser induced solvent bubbles and microplasmas, is responsible for this nonlinear behavior. The use of bacterially-formed Te(0) when combined with an organic chemical host (e.g., PmPV) is a new green method of nanoparticle syntheses. This opens the possibilities of using unique, biologically synthesized materials to advance future nanoelectronic and nanophotonic applications. ?? 2009 Elsevier B.V. All rights reserved.

  12. Strong nonlinear photonic responses from microbiologically synthesized tellurium nanocomposites

    NASA Astrophysics Data System (ADS)

    Liao, Kang-Shyang; Wang, Jun; Dias, Sampath; Dewald, James; Alley, Nigel J.; Baesman, Shaun M.; Oremland, Ronald S.; Blau, Werner J.; Curran, Seamus A.

    2010-01-01

    A new class of nanomaterials, namely microbiologically-formed nanorods composed of elemental tellurium [Te(0)] that forms unusual nanocomposites when combined with poly( m-phenylenevinylene- co-2,5-dioctoxy-phenylenevinylene) (PmPV) is described. These bio-nanocomposites exhibit excellent broadband optical limiting at 532 and 1064 nm. Nonlinear scattering, originating from the laser induced solvent bubbles and microplasmas, is responsible for this nonlinear behavior. The use of bacterially-formed Te(0) when combined with an organic chemical host (e.g., PmPV) is a new green method of nanoparticle syntheses. This opens the possibilities of using unique, biologically synthesized materials to advance future nanoelectronic and nanophotonic applications.

  13. A Family of Bioreducible Poly(disulfide amine)s for Gene Delivery

    PubMed Central

    Ou, Mei; Xu, Rongzuo; Kim, Sun Hwa; Bull, David A.; Kim, Sung Wan

    2009-01-01

    A family of bioreducible poly(disulfide amine)s, which differ in the length of polymethylene spacer [–(CH2)n–] in the main chain and the side chain, has been synthesized. These bioreducible poly(disulfide amine)s exhibit local environment specific degradability and are associated with lower cytotoxicity than branched poly(ethylenimine) (bPEI, 25kDa). These cationic polymers also show higher buffering capacity and protonation degree than bPEI, facilitating the endosomal escape of carried genetic materials. The transfection efficiency of these agents is polymethylene length dependent. Poly(cystaminebisacrylamide-spermine) [poly(CBA-SP);], poly(cystaminebisacrylamide-bis(3-aminopropyl)-1,3-propanediamine) [poly(CBA-APPD);], and poly(cyxtaminebisacrylamide-bis(3-aminopropyl)-ethylenediamine) [ploy(CBA-APED);] with longer propylene [–(CH2)3–] side spacer, demonstrate higher transfection efficacy than the counterpart poly(cystaminebisacrylamide-bis(2-aminoethyl)-1,3-propanediamine) [poly(CBA-AEPD);] and poly(cystaminebisacrylamide-triethylenetetramine) [poly(CBA-TETA);], which have shorter ethylene [–(CH2)2–] side spacer. The poly(CBA-SP), poly(CBA-APPD), poly(CBA-APED) with the main chain spacer of –(CH2)4–, –(CH2)3–, –(CH2)2– demonstrate similar transfection efficiency, indicating the length of polymer main chain spacer has less influence on transfection efficiency. However, with the same short ethylene [–(CH2)2–] side spacer, poly(CBA-AEPD), with the longer main chain oligomethylene units [–(CH2)3–], showed relatively higher transfection efficiency than poly(CBA-TETA), having shorter main chain oligomethylene units [–(CH2)2–]. Of these polymeric carriers, poly(CBA-SP) demonstrated the highest transfection in the C2C12 cell line, while poly(CBA-APED) showed the highest transfection in the Hela cell line. All of these agents showed greater transfection activity than commercialized bPEI 25kDa. The poly(disulfide amine)s are promising

  14. Star-shaped polymers of bio-inspired algae core and poly(acrylamide) and poly(acrylic acid) as arms in dissolution of silica/silicate.

    PubMed

    Chauhan, Kalpana; Patiyal, Priyanka; Chauhan, Ghanshyam S; Sharma, Praveen

    2014-06-01

    Silica, in natural waters (due to weathering of rocks) decreases system performance in water processing industry due to scaling. In view of that, the present work involves the synthesis of novel green star shaped additives of algae core (a bio-inspired material as diatom maintains silicic acid equilibrium in sea water) as silica polymerization inhibitors. Star shaped materials with bio-inspired core and poly(acrylamide) [poly(AAm)] and poly(acrylic acid) [poly(AAc)] arms were synthesized by economical green approach. The proficiency was evaluated in 'mini lab' scale for the synthesized APAAm (Algae-g-poly(AAm)) and APAAc (Algae-g-poly(AAc)) dendrimers (star shaped) in colloidal silica mitigation/inhibition at 35 °C and 55 °C. Synthesized dendrimers were equally proficient in silica inhibition at 12 h and maintains ≥450 ppm soluble silica. However, APAAm dendrimers of generation 0 confirmed better results (≈300 ppm) in contrast to APAAc dendrimers in silica inhibition at 55 °C. Additionally, dendrimers also worked as a nucleator for heterogeneous polymerization to inhibit silica homo-polymerization. APAAm dendrimer test set showed no silica deposit for more than 10 days of inhibition. EDX characterization results support nucleator mechanism with Si content of 6.97%-10.98% by weight in silica deposits (SiO2-APAAm dendrimer composites). PMID:24681378

  15. Poly(cyclohexylethylene)-block-poly(ethylene oxide) block polymers for metal oxide templating

    SciTech Connect

    Schulze, Morgan W.; Sinturel, Christophe

    2015-09-01

    A series of poly(cyclohexylethylene)-block-poly(ethylene oxide) (CEO) diblock copolymers were synthesized through tandem anionic polymerizations and heterogeneous catalytic hydrogenation. Solvent-annealed CEO diblock films were used to template dense arrays of inorganic oxide nanodots via simple spin coating of an inorganic precursor solution atop the ordered film. The substantial chemical dissimilarity of the two blocks enables (i) selective inclusion of the inorganic precursor within the PEO domain and (ii) the formation of exceptionally small feature sizes due to a relatively large interaction parameter estimated from mean-field analysis of the order–disorder transition temperatures of compositionally symmetric samples. UV/ozone treatment following incorporation produces an ordered arrangement of oxide nanodots and simultaneously removes the block polymer template. However, we report the smallest particles (6 ± 1 nm) templated from a selective precursor insertion method to date using a block polymer scaffold.

  16. Synthesis and Properties of Poly(l-lactide)-b-poly (l-phenylalanine) Hybrid Copolymers

    PubMed Central

    Planellas, Marc; Puiggalí, Jordi

    2014-01-01

    Hybrid materials constituted by peptides and synthetic polymers have nowadays a great interest since they can combine the properties and functions of each constitutive block, being also possible to modify the final characteristics by using different topologies. Poly(l-lactide-b-l-phenylalanine) copolymers with various block lengths were synthesized by sequential ring-opening polymerization of l-lactide and the N-carboxyanhydride of l-phenylalanine. The resulting block copolymers were characterized by NMR spectrometry, IR spectroscopy, gel permeation chromatography, MALDI-TOF and UV-vis, revealing the successful incorporation of the polyphenylalanine (PPhe) peptide into the previously formed poly(l-lactide) (PLLA) polymer chain. X-ray diffraction and DSC data also suggested that the copolymers were phase-separated in domains containing either crystalline PLLA or PPhe phases. A peculiar thermal behavior was also found by thermogravimetric analysis when polyphenylalanine blocks were incorporated into polylactide. PMID:25075980

  17. Poly(cyclohexylethylene)-block-poly(ethylene oxide) block polymers for metal oxide templating

    DOE PAGESBeta

    Schulze, Morgan W.; Sinturel, Christophe; Hillmyer, Marc A.

    2015-09-01

    A series of poly(cyclohexylethylene)-block-poly(ethylene oxide) (CEO) diblock copolymers were synthesized through tandem anionic polymerizations and heterogeneous catalytic hydrogenation. Solvent-annealed CEO diblock films were used to template dense arrays of inorganic oxide nanodots via simple spin coating of an inorganic precursor solution atop the ordered film. The substantial chemical dissimilarity of the two blocks enables (i) selective inclusion of the inorganic precursor within the PEO domain and (ii) the formation of exceptionally small feature sizes due to a relatively large interaction parameter estimated from mean-field analysis of the order–disorder transition temperatures of compositionally symmetric samples. UV/ozone treatment following incorporation produces anmore » ordered arrangement of oxide nanodots and simultaneously removes the block polymer template. However, we report the smallest particles (6 ± 1 nm) templated from a selective precursor insertion method to date using a block polymer scaffold.« less

  18. Laboratory Syntheses of Insect Pheromones.

    ERIC Educational Resources Information Center

    Cormier, Russell A.; Hoban, James N.

    1984-01-01

    Provides background information and procedures for the multi-step synthesis of tiger moth and boll weevil pheromones (sex attractants). These syntheses require several laboratory periods. The tiger moth pheromone synthesis is suitable for introductory organic chemistry while the boll weevil pheromone is recommended for an advanced laboratory…

  19. Method of synthesizing pyrite nanocrystals

    DOEpatents

    Wadia, Cyrus; Wu, Yue

    2013-04-23

    A method of synthesizing pyrite nanocrystals is disclosed which in one embodiment includes forming a solution of iron (III) diethyl dithiophosphate and tetra-alkyl-ammonium halide in water. The solution is heated under pressure. Pyrite nanocrystal particles are then recovered from the solution.

  20. Ac conduction in conducting poly pyrrole-poly vinyl methyl ether polymer composite materials

    SciTech Connect

    Saha, S.K.; Mandal, T.K.; Mandal, B.M.; Chakravorty, D.

    1997-03-01

    Composite materials containing conducting polypyrrole and insulating poly (vinyl methyl ether) (PVME) have been synthesized by oxidative polymerization of pyrrole in ethanol using FeCl{sub 3} oxidant in the presence of PVME. The ac conductivity measurements have been carried out in the frequency range of 100 Hz to 10 MHz and in the temperature range of 110 to 350 K. The frequency dependent conductivity has been explained on the basis of a small polaron tunnelling mechanism. {copyright} {ital 1997 American Institute of Physics.}

  1. Synthesis and characterization of β-napthalene sulphonic acid doped poly(o-anisidine)

    NASA Astrophysics Data System (ADS)

    Sangamithirai, D.; Narayanan, V.; Stephen, A.

    2014-04-01

    Poly(o-anisidine) doped with β-napthalene sulphonic acid (β-NSA) was synthesized using ammonium persulphate as an oxidizing agent. The polymer was characterized by using FTIR, XRD and conductivity measurements. The FTIR spectra reveal the presence of functional groups that account for the formation of polymer. The structure was characterized by XRD. The conductivity of the poly(o-anisidine) salt was found to be 2.25 × 10-6 S/m.

  2. Thermoresponse improvement of poly(N-isopropylacrylamide) hydrogels via formation of poly(sodium p-styrenesulfonate) nanophases.

    PubMed

    Li, Jingang; Cong, Houluo; Li, Lei; Zheng, Sixun

    2014-08-27

    The block copolymer networks composed of poly(N-isopropylacrylamide) (PNIPAM) and poly(sodium p-styrenesulfonate) were synthesized via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization with α,ω-didithiobenzoate-terminated poly(sodium p-styrenesulfonate) (PSSNa) as the macromolecular chain transfer agent. It was found that the block copolymer networks were microphase-separated as evidenced by means of transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). In the block copolymer networks, spherical or cylindrical PSSNa microdomains were finely dispersed into continuous PNIPAM matrixes. In comparison with unmodified PNIPAM hydrogel, the nanostructured hydrogels displayed improved thermoresponsive properties. In addition, the swelling ratios of the PSSNa-modified PNIPAM hydrogels were significantly higher than that of plain PNIPAM hydrogel. The improvement of thermoresponse was attributable to the formation of the PSSNa nanophases, which promoted the transportation of water molecules in the cross-linked networks. PMID:25036696

  3. Research Update: Triblock copolymers as templates to synthesize inorganic nanoporous materials

    NASA Astrophysics Data System (ADS)

    Li, Yunqi; Bastakoti, Bishnu Prasad; Yamauchi, Yusuke

    2016-04-01

    This review focuses on the application of triblock copolymers as designed templates to synthesize nanoporous materials with various compositions. Asymmetric triblock copolymers have several advantages compared with symmetric triblock copolymers and diblock copolymers, because the presence of three distinct domains can provide more functional features to direct the resultant nanoporous materials. Here we clearly describe significant contributions of asymmetric triblock copolymers, especially polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (abbreviated as PS-b-P2VP-b-PEO).

  4. Ketimine modifications as a route to novel amorphous and derived semicrystalline poly(arylene ether ketone) homo- and copolymers

    NASA Technical Reports Server (NTRS)

    Mohanty, D. K.; Lowery, R. C.; Lyle, G. D.; Mcgrath, J. E.

    1987-01-01

    A series of amine terminal amorphous poly(arylene ether ketone) oligomers of controlled molecular weights (2-15 K) were synthesized. These oligomers have been found to undergo 'self-crosslinking' reactions upon heating above 220 C, via the reaction of the terminal amine groups with the in-chain keto carbonyl functionalities. The resulting networks are ductile, chemically resistant, and nonporous. The networks obtained via generated ketimine functionality were characterized by solid state NMR. They have also been found to be remarkably stable toward hydrolysis. Ketimine functional bishalide monomers have also been synthesized. Such monomers have been utilized to synthesize a wide variety of amorphous poly(arylene ether) ketimine polymers. A high molecular weight hydroquinone functional poly(arylene ether) ketimine has been acid treated to regenerate a poly(arylene ether ketone) backbone in solution. This novel procedure thus allows for the synthesis of important matrix resins under relatively mild conditions.

  5. Molecular crystals as precursors for poly-nitrogen

    NASA Astrophysics Data System (ADS)

    Borstad, Gustav; Ciezak-Jenkins, Jennifer

    The application of pressure to matter results in dramatic modifications of its properties. The compression of molecular crystals first eliminates ``empty'' space between the molecules. It then alters the electron density distribution, favoring the increase of atomic coordination and the formation of polymers. The polymerization of low-Z compounds into covalently-bonded networks in three dimensions tend to generate materials characterized by superconductivity, super-hardness, and high-energy density.1 Poly-nitrogen (analogous to diamond) has been synthesized under extreme conditions above 100 GPa and 2000 K in diamond anvil cells, but could not be recovered to ambient conditions.2 A useful form of poly-nitrogen would have to be synthesized at low-pressure with enhanced stability at ambient conditions. The changes in the intermolecular and intramolecular interactions with pressure play a crucial role in the synthesizing and stabilizing of the structure as well as in tuning its properties. In this talk, we provide Raman and x-ray diffraction data on nitrogen-containing compound biuret and compare it to work on other possible poly-nitrogen precursors. During this project, coauthor GB was supported in part by an appointment to the Postdoctoral Research Program at the US Army Research Laboratory administered by the Oak Ridge Associated Universities.

  6. Synthesis and Characterization of Multiwalled Carbon Nanotubes/Poly(HEMA-co-MMA) by Utilizing Click Chemistry.

    PubMed

    Bach, Long Giang; Cao, Xuan Thang; Islam, Md Rafiqul; Jeong, Yeon Tae; Kim, Jong Su; Lim, Kwon Taek

    2016-03-01

    The hybrid material consisting of multi walled carbon nanotubes (MWNTs) and poly(2-hydroxyethylmethacrylate-co-methylmethacrylate) [poly(HEMA-co-MMA)] was synthesized by a combination of RAFT and Click chemistry. In the primary stage, the copolymer poly(HEMA-co-MMA) was prepared by applying RAFT technique. Alkynyl side groups were incorporated onto the poly(HEMA-co-MMA) backbone by esterification reaction. Then, MWNTs-N3 was prepared by treating MWNTs with 4-azidobutylamine. The click coupling reaction between azide-functionalized MWNTs (MWNTs-N3) and the alkyne-functionalized random copolymer ((HEMA-co-MMA)-Alkyne) with the Cu(I)-catalyzed [3+2] Huisgen cycloaddition afforded the hybrid compound. The structure and properties of poly(MMA-co-HEMA)-g-MWNTs were investigated by FT-IR, EDX and TGA measurements. The copolymer brushes were observed to be immobilized onto the functionalized MWNTs by SEM and TEM analysis. PMID:27455744

  7. PolyMorphine: an innovative biodegradable polymer drug for extended pain relief

    PubMed Central

    Rosario-Meléndez, Roselin; Harris, Carolyn L.; Delgado-Rivera, Roberto; Yu, Lei; Uhrich, Kathryn E.

    2012-01-01

    Morphine, a potent narcotic analgesic used for the treatment of acute and chronic pain, was chemically incorporated into a poly(anhydride-ester) backbone. The polymer termed “PolyMorphine”, was designed to degrade hydrolytically releasing morphine in a controlled manner to ultimately provide analgesia for an extended time period. PolyMorphine was synthesized via melt-condensation polymerization and its structure was characterized using proton and carbon nuclear magnetic resonance spectroscopies, and infrared spectroscopy. The weight-average molecular weight and the thermal properties were determined. The hydrolytic degradation pathway of the polymer was determined by in vitro studies, showing that free morphine is released. In vitro cytocompatibility studies demonstrated that PolyMorphine is non-cytotoxic towards fibroblasts. In vivo studies using mice showed that PolyMorphine provides analgesia for 3 days, 20 times the analgesic window of free morphine. The animals retained full responsiveness to morphine after being subjected to an acute morphine challenge. PMID:22877734

  8. New aromatic activated dihalides and bisphenol monomers for the preparation of novel poly(arylene ethers)

    NASA Technical Reports Server (NTRS)

    Wolfe, James F.

    1993-01-01

    The goal of this research program was to synthesize a series of unique monomers of type I to be utilized at NASA-Langley in the preparation of new poly(arylene ether ketones), poly(arylene ether ketosulfones), and poly(arylene ether ketophosphine oxides). These A-A and A-B monomer systems, which possess activated aryl halide and/or phenolic end groups, are accessible via condensation reactions of appropriately substituted aryl acetonitrile carbanions with activated aryl dihalides followed by oxidative decyanation.

  9. Frequency Synthesizer For Tracking Filter

    NASA Technical Reports Server (NTRS)

    Randall, Richard L.

    1990-01-01

    Digital frequency-synthesizing subsystem generates trains of pulses, free of jitter, for use as frequency-control signals in tracking filters. Part of assembly of electronic equipment used to measure vibrations in bearings in rotating machinery. Designed to meet requirements for tracking narrow-band cage-rotation and ball-pass components of vibrations, as discussed in "Frequency-Tracking Error Detector" (MFS-29538) and "Ball-Pass Cage-Modulation Detector" (MFS-29539). Synthesizer includes preset counter, output of which controls signal for ball-pass filter. Input to this preset counter updated every 2 microseconds: responds almost immediately, effectively eliminating relatively long response time (lock-in time) and phase jitter.

  10. Catalytic method for synthesizing hydrocarbons

    DOEpatents

    Sapienza, Richard S.; Sansone, Michael J.; Slegeir, William A. R.

    1984-01-01

    A method for synthesizing hydrocarbons from carbon monoxide and hydrogen by contacting said gases with a slurry of a catalyst composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants.

  11. Catalytic method for synthesizing hydrocarbons

    DOEpatents

    Sapienza, R.S.; Sansone, M.J.; Slegeir, W.A.R.

    A method for synthesizing hydrocarbons from carbon monoxide and hydrogen by contacting said gases with a slurry of a catalyst composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants.

  12. Determinism in synthesized chaotic waveforms.

    PubMed

    Corron, Ned J; Blakely, Jonathan N; Hayes, Scott T; Pethel, Shawn D

    2008-03-01

    The output of a linear filter driven by a randomly polarized square wave, when viewed backward in time, is shown to exhibit determinism at all times when embedded in a three-dimensional state space. Combined with previous results establishing exponential divergence equivalent to a positive Lyapunov exponent, this result rigorously shows that such reverse-time synthesized waveforms appear equally to have been produced by a deterministic chaotic system. PMID:18517561

  13. SYNTH - Gamma Ray Spectrum Synthesizer

    Energy Science and Technology Software Center (ESTSC)

    2009-05-18

    SYNTH was designed to synthesize the results of typical gamma-ray spectroscopy experiments. The code allows a user to specify the physical characteristics of a gamma-ray source, the quantity of radionuclides emitting gamma radiation, the source-to-detector distance and the presence and type of any intervening absorbers, the size and type of the gamma-ray detector, and the electronic set-up used to gather the data.

  14. TSS-Thermal Synthesizer System

    NASA Technical Reports Server (NTRS)

    Chimenti, Edward; Rickman, Steven; Vogt, Robert; Longo, Carlos R. Ortiz; Bauman, Noel; Lepore, Joseph; Mackey, Phil; Pavlovsky, James, II; Welch, Mark; Fogerson, Peter; Dawber, Mark; Fong, Cynthia Jone; Hecke, Peter; Morrison, Susan; Castillo, Ernie; Chou, ZU; Fried, Lawrence; Howard, Jerry; Lombardi, Mike; Middleton, Jack

    1996-01-01

    Thermal Synthesizer System (TSS) is integrated set of thermal-analysis application programs designed to solve problems encountered by thermal engineers. Combines functionality of Systems Improved Numerical Differencing Analyzer/Fluid Integrator (SINDA/FLUINT) and radiation analysis with friendly and easily understood user-interface environment coupled with powerful interactive color graphics and geometric modeling capability. Enables thermal engineers to spend more time solving engineering problems instead of laboriously constructing and verifying math models. Written in FORTRAN and C language.

  15. Method for synthesizing powder materials

    DOEpatents

    Buss, R.J.; Ho, P.

    1988-01-21

    A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400/degree/K (127/degree/C). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material. 1 fig.

  16. Poly(3-Hydroxypropionate): a Promising Alternative to Fossil Fuel-Based Materials

    PubMed Central

    Andreeßen, Björn; Taylor, Nicolas

    2014-01-01

    Polyhydroxyalkanoates (PHAs) are storage compounds synthesized by numerous microorganisms and have attracted the interest of industry since they are biobased and biodegradable alternatives to fossil fuel-derived plastics. Among PHAs, poly(3-hydroxypropionate) [poly(3HP)] has outstanding material characteristics and exhibits a large variety of applications. As it is not brittle like, e.g., the best-studied PHA, poly(3-hydroxybutyrate) [poly(3HB)], it can be used as a plasticizer in blends to improve their properties. Furthermore, 3-hydroxypropionic acid (3HP) is considered likely to become one of the new industrial building blocks, and it can be obtained from poly(3HP) by simple hydrolysis. Unfortunately, no natural organism is known to accumulate poly(3HP) so far. Thus, several efforts have been made to engineer genetically modified organisms capable of synthesizing the homopolymer or copolymers containing 3HP. In this review, the achievements made so far in efforts to obtain biomass which has accumulated poly(3HP) or 3HP-containing copolymers, as well as the properties of these polyesters and their applications, are compiled and evaluated. PMID:25149521

  17. Synthesis, characterization and antimicrobial applications of zinc oxide nanoparticles loaded gum acacia/poly(SA) hydrogels.

    PubMed

    Bajpai, S K; Jadaun, Mamta; Tiwari, Seema

    2016-11-20

    In this work, zinc oxide nanoparticles were synthesized in-situ within the gum acacia/poly (acrylate) hydrogel network using hydrothermal approach. The synthesized zinc oxide nanoparticles were characterized by Surface plasmon resonance (SPR), X-Ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscopy (SEM). The water absorption behavior of ZnO/GA/poly(SA) hydrogels was investigated in the phosphate buffer saline (PBS) of pH 7.4 at 37°C. The water uptake data were analyzed with the help of various kinetic models. Finally, the antimicrobial action of nanocomposites was studied using E. coli as model bacteria. PMID:27561472

  18. Injectable polyHIPEs as high-porosity bone grafts.

    PubMed

    Moglia, Robert S; Holm, Jennifer L; Sears, Nicholas A; Wilson, Caitlin J; Harrison, Dawn M; Cosgriff-Hernandez, Elizabeth

    2011-10-10

    Polymerization of high internal phase emulsions (polyHIPEs) is a relatively new method for the production of high-porosity scaffolds. The tunable architecture of these polyHIPE foams makes them attractive candidates for tissue engineered bone grafts. Previously studied polyHIPE systems require either toxic diluents or high cure temperatures which prohibit their use as an injectable bone graft. In contrast, we have developed an injectable polyHIPE that cures at physiological temperatures to a rigid, high-porosity foam. First, a biodegradable macromer, propylene fumarate dimethacrylate (PFDMA), was synthesized that has appropriate viscosity and hydrophobicity for emulsification. The process of surfactant selection is detailed with particular focus on the key structural features of both polymer (logP values, hydrogen bond acceptor sites) and surfactant (HLB values, hydrogen bond donor sites) that enable stable HIPE formation. Incubation of HIPEs at 37 °C was used to initiate radical cross-linking of the unsaturated double bond of the methacrylate groups to polymerize the continuous phase and lock in the emulsion geometry. The resulting polyHIPEs exhibited ~75% porosity, pore sizes ranging from 4 to 29 μm, and an average compressive modulus and strength of 33 and 5 MPa, respectively. These findings highlight the great potential of these scaffolds as injectable, tissue engineered bone grafts. PMID:21861465

  19. Injectable PolyHIPEs as High Porosity Bone Grafts

    PubMed Central

    Moglia, Robert S.; Holm, Jennifer L.; Sears, Nicholas A.; Wilson, Caitlin J.; Harrison, Dawn M.; Cosgriff-Hernandez, Elizabeth

    2011-01-01

    Polymerization of high internal phase emulsions (polyHIPEs) is a relatively new method for the production of high porosity scaffolds. The tunable architecture of these polyHIPE foams make them attractive candidates for tissue engineered bone grafts. Previously studied polyHIPE systems require either toxic diluents or high cure temperatures which prohibit their use as an injectable bone graft. In contrast, we have developed an injectable polyHIPE that cures at physiological temperatures to a rigid, high-porosity foam. First, a biodegradable macromer, propylene fumarate dimethacrylate (PFDMA), was synthesized that has appropriate viscosity and hydrophobicity for emulsification. The process of surfactant selection is detailed with particular focus on the key structural features of both polymer (log P values, hydrogen bond acceptor sites) and surfactant (HLB values, hydrogen bond donor sites) that enable stable HIPE formation. Incubation of HIPEs at 37°C was used to initiate radical crosslinking of the unsaturated double bond of the methacrylate groups to polymerize the continuous phase and lock in the emulsion geometry. The resulting polyHIPEs exhibited ~75% porosity, pore sizes ranging from 4 to 29 μm, and an average compressive modulus and strength of 33 and 5 MPa, respectively. These findings highlight the great potential of these scaffolds as injectable, tissue engineered bone grafts. PMID:21861465

  20. PREPARATION OF BLOCK COPOLYMERS OF POLY(STYRENE) AND POLY(T-BUTYL ACRYLATE) OF VARIOUS MOLECULAR WEIGHTS AND ARCHITECTURES BY ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

    EPA Science Inventory

    Block copolymers of polystyrene and poly(t-butyl acrylate) were prepared using atom transfer radical polymerization techniques. These polymers were synthesized with a CuBr/N,N,N,N

  1. Biodegradable nanoparticles of amphiphilic triblock copolymers based on poly(3-hydroxybutyrate) and poly(ethylene glycol) as drug carriers.

    PubMed

    Chen, Cheng; Yu, Chung Him; Cheng, Yin Chung; Yu, Peter H F; Cheung, Man Ken

    2006-09-01

    New amorphous amphiphilic triblock copolymers of poly(3-hydroxybutyrate)-poly(ethylene glycol)-poly(3-hydroxybutyrate) (PHB-PEG-PHB) were synthesized using the ring-opening copolymerization of beta-butyrolactone monomer. They were characterized by fluorescence, SEM and (1)H NMR. These triblock copolymers can form biodegradable nanoparticles with core-shell structure in aqueous solution. Comparing to the poly(ethylene oxide)-PHB-poly(ethylene oxide) (PEO-PHB-PEO) copolymers, these nanoparticles exhibited much smaller critical micelle concentrations and better drug loading properties, which indicated that the nanoparticles were very suitable for delivery carriers of hydrophobic drugs. The drug release profile monitored by fluorescence showed that the release of pyrene from the PHB-PEG-PHB nanoparticles exhibited the second-order exponential decay behavior. The initial biodegradation rate of the PHB-PEG-PHB nanoparticles was related to the enzyme amount, the initial concentrations of nanoparticle dispersions and the PHB block length. The biodegraded products detected by (1)H NMR contained 3HB monomer, dimer and minor trimer, which were safe to the body. PMID:16740306

  2. Solubilization of docetaxel in poly(ethylene oxide)-block-poly(butylene/styrene oxide) micelles.

    PubMed

    Elsabahy, Mahmoud; Perron, Marie-Eve; Bertrand, Nicolas; Yu, Ga-Er; Leroux, Jean-Christophe

    2007-07-01

    Poly(ethylene oxide)-block-poly(styrene oxide) (PEO-b-PSO) and PEO-b-poly(butylene oxide) (PEO-b-PBO) of different chain lengths were synthesized and characterized for their self-assembling properties in water by dynamic/static light scattering, spectrofluorimetry, and transmission electron microscopy. The resulting polymeric micelles were evaluated for their ability to solubilize and protect the anticancer drug docetaxel (DCTX) from degradation. The drug release kinetics as well as the cytotoxicity of the loaded micelles were assessed in vitro. All polymers formed micelles with a highly viscous core at low critical association concentrations (<10 mg/L). Micelle morphology depended on the nature of the hydrophobic block, with PBO- and PSO-based micelles yielding monodisperse spherical and cylindrical nanosized aggregates, respectively. The maximum solubilization capacity for DCTX ranged from 0.7 to 4.2% and was the highest for PSO micelles exhibiting the longest hydrophobic segment. Despite their high affinity for DCTX, PEO-b-PSO micelles were not able to efficiently protect DCTX against hydrolysis under accelerated stability testing conditions. Only PEO-b-PBO bearing 24 BO units afforded significant protection against degradation. In vitro, DCTX was released slower from the latter micelles, but all formulations possessed a similar cytotoxic effect against PC-3 prostate cancer cells. These data suggest that PEO-b-P(SO/BO) micelles could be used as alternatives to conventional surfactants for the solubilization of taxanes. PMID:17579476

  3. Block poly(ester-urethane)s based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) and poly(3-hydroxyhexanoate-co-3-hydroxyoctanoate).

    PubMed

    Chen, Zhifei; Cheng, Shaoting; Xu, Kaitian

    2009-04-01

    A series of block poly(ester-urethane) poly(3/4HB-HHxHO) urethanes (abbreviated as PUHO) based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB-diol) and poly(3-hydroxyhexanoate-co-3-hydroxyoctanoate) (PHHxHO-diol) segments were synthesized by a facile way of melting polymerization using 1,6-hexamethylene diisocyanate (HDI) as the coupling agent, with different 3HB, 4HB, HHxHO compositions and segment lengths. The chemical structure, molecular weight and distribution were systematically characterized by (1)H, (13)C nuclear magnetic resonance spectrum (NMR), two-dimensional correlation spectroscopy (COSY ((1)H, (13)C) NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The thermal property was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hydrophilicity was investigated by static contact angle of water and CH(2)I(2). DSC revealed that the poly(3/4HB-HHxHO) urethanes are almost amorphous with a little crystallinity (less than 6%) and T(g) from -23 degrees C to -3 degrees C. The polyurethanes are more hydrophobic (water contact angle 88 degrees -117 degrees ) than the P3/4HB and PHHxHO raw materials. The lactate dehydrogenase (LDH) assay and platelet adhesion determination showed that the obtained polyurethanes have much higher platelet adhesion property than raw materials and common biodegradable polymers polylactic acid (PLA) and poly(3-hydroxybutyrate) (PHB). Hydrophobicity and crystallinity degree are important factors to affect the platelet adhesion. All the properties can be tailored by changing the composition and segment length of prepolymers P3/4HB-diol and PHHxHO-diol. PMID:19167751

  4. Poly(Lactic Acid) Hemodialysis Membranes with Poly(Lactic Acid)-block-Poly(2-Hydroxyethyl Methacrylate) Copolymer As Additive: Preparation, Characterization, and Performance.

    PubMed

    Zhu, Lijing; Liu, Fu; Yu, Xuemin; Xue, Lixin

    2015-08-19

    Poly(lactic acid) (PLA) hemodialysis membranes with enhanced antifouling capability and hemocompatibility were developed using poly(lactic acid)-block-poly(2-hydroxyethyl methacrylate) (PLA-PHEMA) copolymers as the blending additive. PLA-PHEMA block copolymers were synthesized via reversible addition-fragmentation (RAFT) polymerization from aminolyzed PLA. Gel permeation chromatography (GPC) and (1)H-nuclear magnetic resonance ((1)H NMR) were applied to characterize the synthesized products. By blending PLA with the amphiphilic block copolymer, PLA/PLA-PHEMA membranes were prepared by nonsolvent induced phase separation (NIPS) method. Their chemistry and structure were characterized with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results revealed that PLA/PLA-PHEMA membranes with high PLA-PHEMA contents exhibited enhanced hydrophilicity, water permeability, antifouling and hemocompatibility. Especially, when the PLA-PHEMA concentration was 15 wt %, the water flux of the modified membrane was about 236 L m(-2) h(-1). Its urea and creatinine clearance was more than 0.70 mL/min, lysozyme clearance was about 0.50 mL/min, BSA clearance was as less as 0.31 mL/min. All the results suggest that PLA-PHEMA copolymers had served as effective agents for optimizing the property of PLA-based membrane for hemodialysis applications. PMID:26222398

  5. Temperature independence of the composition of triglyceride fatty acids synthesized de novo by the mosquito.

    PubMed

    Van Handel, E

    1966-01-01

    The hypothesis that depot fat is more unsaturated when it is synthesized at lower temperatures was tested in the mosquito. Female mosquitoes (Aedes sollicitans) were starved until no triglycerides remained. A single dose of sugar was fed and the mosquitoes were maintained at different temperatures. Approximately the same amount of triglyceride was synthesized per mosquito at each temperature, although at different rates. Mosquitoes maintained at low temperatures did not synthesize more unsaturated triglycerides than those at higher temperatures: the fatty acid composition was essentially the same from 10 to 35 degrees. The triglycerides synthesized from sugar contained no poly-unsaturated fatty acids. Total amounts and composition of phospholipid fatty acids remained unaltered during sugar feeding. When deprived of food, the mosquitoes catabolized triglyceride fatty acids randomly; cold-exposure did not cause selective retention or utilization of any individual fatty acid. PMID:4378885

  6. A novel PLED architecture containing biologically synthesized gold nanoparticles and ultra thin silver layer

    NASA Astrophysics Data System (ADS)

    Pıravadılı Mucur, Selin; Tekin, Emine; San, Sait Eren; Duygulu, Özgür; Öztürk, Hasan Ümit; Utkan, Güldem; Denizci, Aziz Akın

    2015-09-01

    The influences of biologically synthesized gold nanoparticles (bio-GNPs) and ultra thin silver layer (UTSL) on the polymer light emitting diodes (PLEDs) are investigated for the first time. The performance of the fabricated PLEDs is enhanced by embedding of bio-GNPs into the hole transport layer (HTL). Furthermore, the tailored device architecture containing UTSL increases the electron transport through lightning rod effect. Bio-GNPs are successfully produced as spherical shape with size of circa 10.4 nm. Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene (MEH-PPV) and [poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate); (PEDOT:PSS)/bio-GNPs blends are used as an active layer and HTL, respectively. Novel PLEDs fabricated with 0.125 wt% bio-GNPs/PEDOT:PSS and 0.5 nm UTSL exhibit nearly 2.5-fold enhancement in the device efficiency.

  7. Physiologically driven avian vocal synthesizer

    NASA Astrophysics Data System (ADS)

    Sitt, Jacobo D.; Arneodo, Ezequiel M.; Goller, Franz; Mindlin, Gabriel B.

    2010-03-01

    In this work, we build an electronic syrinx, i.e., a programmable electronic device capable of integrating biomechanical model equations for the avian vocal organ in order to synthesize song. This vocal prosthesis is controlled by the bird’s neural instructions to respiratory and the syringeal motor systems, thus opening great potential for studying motor control and its modification by sensory feedback mechanisms. Furthermore, a well-functioning subject-controlled vocal prosthesis can lay the foundation for similar devices in humans and thus provide directly health-related data and procedures.

  8. Method of synthesizing tungsten nanoparticles

    DOEpatents

    Thoma, Steven G; Anderson, Travis M

    2013-02-12

    A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

  9. Record high mobilities for regioregular poly(3-octylthiophene)

    NASA Astrophysics Data System (ADS)

    Sauvé, Geneviève; Liu, Junying; Zhang, Rui; Kowalewski, Tomasz; McCullough, Richard D.

    2007-09-01

    Regioregular poly(3-alkylthiophene)s are promising candidates for plastic electronics. In particular, poly(3- hexylthiophene) (P3HT) has attracted considerable interest due to its excellent field effect mobility. However, not much attention has been given to poly(3-alkylthiophene)s with longer alkyl side chains, mainly because a few studies reported that longer side chain length was detrimental to field effect mobility. However, these past studies used untreated SiO II as the gate dielectric and commercially available polymers synthesized by the Rieke method. Here, all polymers tested were synthesized in house using our quasi-living GRIM method to yield well-defined clean polymers. For our first study, we synthesized P3HT and regioregular poly(3-octylthiohene) (P3OT), both with a high molecular weight (Mn of 40kDa and 35kDa, respectively). Regioregular P3HT required some sonication to dissolve in chloroform, whereas P3OT dissolved readily in chloroform at room temperature. Hole mobility was measured using bottom-contact geometry, with SiO II as gate dielectric. The SiO II surface was either untreated, or chemically treated with octyltrichlorosilane. Average mobility on untreated SiO II was 0.09 cm2/Vs for P3HT and 0.03 cm2/Vs for P3OT. Average mobility on OTS-8 treated SiO II, on the other hand, was 0.13 cm2/Vs for P3HT and 0.19 cm2/Vs for P3OT. The OTS-8 treatment therefore dramatically improved the mobility of P3OT. Both polymers had a maximum mobility of about 0.2 cm2/Vs for channel lengths >=10 μm, and a mobility of 0.22 cm2/Vs was obtained several times for P3OT. To our knowledge, this is by far the highest mobility reported for P3OT.

  10. Synthesis and Structure-Property Relationships of Poly(sulfone)s for Anion Exchange Membranes

    SciTech Connect

    Yan, JL; Moore, HD; Hibbs, MR; Hickner, MA

    2013-10-05

    Membranes based on cationic polymers that conduct anions are important for enabling alkaline membrane fuel cells and other solid-state electrochemical devices that operate at high pH. Anion exchange membranes with poly(arylene ether sulfone) backbones are demonstrated by two routes: chloromethylation of commercially available poly(sulfone)s or radical bromination of benzylmethyl moieties in poly(sulfone)s containing tetramethylbisphenol A monomer residues. Polymers with tethered trimethylbenzyl ammonium moieties resulted from conversion of the halomethyl groups by quaternization with trimethyl amine. The water uptake of the chloromethylated polymers was dependent on the type of poly(sulfone) backbone for a given IEC. Bisphenol A-based Udel (R) poly(sulfone) membranes swelled in water to a large extent while membranes from biphenol-based Radel (R) poly(sulfone), a stiffer backbone than Udel, only showed moderate water uptake. The water uptake of cationic poly(sulfone)s was further reduced by synthesizing tetramethylbisphenol A and 4,4-biphenol-containing poly(sulfone) copolymers where the ionic groups were clustered on the tetramethylbisphenol A residues. The conductivity of all samples scaled with the bulk water uptake. The hydration number of the membranes could be increased by casting membranes from the ionic form polymers versus converting the halomethyl form cast polymers to ionic form in the solid state. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1790-1798, 2013

  11. Synthesis of poly(silanes) and poly(silane)-modified silicones for use as novel initiator systems

    NASA Astrophysics Data System (ADS)

    Goldslager, Barry Andrew

    The development of new methods for the synthesis of polymeric silanes represents an exciting new field in organosilicon chemistry. The synthetic methods developed in this research were used to produce reactive polymeric silanes which in turn were used in applications as photoinitiators/modifiers or as self curing resins. This thesis describes investigations of the synthesis of a variety of reactive polymeric silanes, modification of the polymeric silanes and their use as photoinitiators and self curing resins. The silanes were synthesized by either Wurtz type coupling, which uses a sodium dispersion to couple halogenated silanes together, or by metallocene catalysis, which uses transition metal catalysts to couple silicon hydrides together through dehydrogenative coupling. The resulting materials were demonstrated to be useful as photoinitiators for acrylic/methacrylic systems and that they can be modified for use in other systems. The modification of the polymeric silanes where carried out using a either a hydrosilylation reaction which involves the coupling of an active silicon hydride with an active vinyl group, or a condensation reaction between an active chlorosilane with an active hydroxyl group. Several unique materials were synthesized using these two methods and consist of the following: (1) Linear poly(phenylsdane)-graft-vinyl terminated poly(dimethylsiloxane); (2) Networked poly(phenylisdane)-graft-vinyl terminated poly(dimethylsiloxane); (3) Oligo(methylphenyisilane)-alt-vinyl terminated poly(dimethylsiloxane); (4) Various polymeric silanes. These materials where successfully used as photoinitators for acrylate and methacrylate systems such as isobornyl acrylate, 2-hydroxypropyl acrylate, vinyl terminated polydimethylsiloxane, and self curing resins which showed excellent properties such as nontacky surfaces, high glass transition temperatures, Tgs, and crosslinked materials for use as potting agents. The modified silanes showed good solubility in many

  12. Hydrophilic polymer composites synthesized by electrospinning under dense carbon dioxide

    NASA Astrophysics Data System (ADS)

    Wahyudiono, Okamoto, Koichi; Machmudah, Siti; Kanda, Hideki; Goto, Motonobu

    2015-12-01

    Electrospinning technique is feasible in some applications, it has attracted more attention in recent years. Various polymers have been successfully electrospun into ultrafine fibers in solvent solution and some in melt form. In this work, polyvinylpyrrolidone (PVP) as a hydrophilic polymer would be synthesized by electrospinning under dense carbon dioxide (CO2). The experiments were performed at 40 °C and ˜ 5 MPa. During the electrospinning process, the applied voltage was 10-17 kV and the distance of nozzle and collector was 8 cm. The concentration of PVP solution as a major component was 4 wt%. The results showed that the fibers surface morphology from PVP which blended with poly L-lactide acid (PLLA) were smooth with hollow core fibers at 5 MPa. At the same conditions, PVP-carbon nanotube was also successfully generated into electrospun fiber products with diameter ˜ 2 μm.

  13. Poly(Amido Amine)s Containing Agmatine and Butanol Side Chains as Efficient Gene Carriers.

    PubMed

    Won, Young-Wook; Ankoné, Marc; Engbersen, Johan F J; Feijen, Jan; Kim, Sung Wan

    2016-04-01

    A new type of bioreducible poly(amido amine) copolymer is synthesized by the Michael addition polymerization of cystamine bisacrylamide (CBA) with 4-aminobutylguanidine (agmatine, AGM) and 4-aminobutanol (ABOL). Since the positively charged guanidinium groups of AGM and the hydroxybutyl groups of ABOL in the side chains have shown to improve the overall transfection efficiency of poly(amido amine)s, it is hypothesized that poly(CBA-ABOL/AGM) synthesized at the optimal ratio of both components would result in high transfection efficiency and minimal toxicity. In this study, a series of the poly(CBA-ABOL/AGM) copolymers is synthesized as gene carriers. The polymers are characterized and luciferase transfection efficiencies of the polymers in various cell lines are investigated to select the ideal ratio between AGM and ABOL. The poly(CBA-ABOL/AGM) containing 80% AGM and 20% ABOL has shown the best transfection efficiency with the lowest cytotoxicity, indicating that this polymer is very promising as a potent and nontoxic gene carrier. PMID:26663734

  14. System for synchronizing synthesizers of communication systems

    NASA Technical Reports Server (NTRS)

    Enriquez, E. A. (Inventor); Gookin, R. E.

    1979-01-01

    Frequency synthesizers at first and second stations that communicate with each other via a transmission link having a constant propagation delay time are started and synchronized by transmitting a tone from the first station to the second station via the link. The frequencies derived from the synthesizer at the second station are received at the first station and are combined with the frequencies derived from the synthesizer at the first station to derive a constant beat frequency as the two synthesizers are stepped.

  15. Synthesizing Smart Polymeric and Composite Materials

    NASA Astrophysics Data System (ADS)

    Gong, Chaokun

    Smart materials have been widely investigated to explore new functionalities unavailable to traditional materials or to mimic the multifunctionality of biological systems. Synthetic polymers are particularly attractive as they already possess some of the attributes required for smart materials, and there are vast room to further enhance the existing properties or impart new properties by polymer synthesis or composite formulation. In this work, three types of smart polymer and composites have been investigated with important new applications: (1) healable polymer composites for structural application and healable composite conductor for electronic device application; (2) conducting polymer polypyrrole actuator for implantable medical device application; and (3) ferroelectric polymer and ceramic nanoparticles composites for electrocaloric effect based solid state refrigeration application. These application entail highly challenging materials innovation, and my work has led to significant progress in all three areas. For the healable polymer composites, well known intrinsically healable polymer 2MEP4F (a Diels-Alder crosslinked polymer formed from a monomer with four furan groups and another monomer with two maleimide groups) was first chosen as the matrix reinforced with fiber. Glass fibers were successfully functionalized with maleimide functional groups on their surface. Composites from functionalized glass fibers and 2MEP4F healable polymer were made to compare with composites made from commercial carbon fibers and 2MEP4F polymer. Dramatically improved short beam shear strength was obtained from composite of functionalized glass fibers and 2MEP4F polymer. The high cost of 2MEP4F polymer can potentially limit the large-scale application of the developed healable composite, we further developed a new healable polymer with much lower cost. This new polymer was formed through the Diels-Alder crosslinking of poly(furfuryl alcohol) (PFA) and 1,1'-(Methylenedi-4

  16. Sophorolipid-derived unsaturated and epoxy fatty acid estolides as plasticizers for poly(3-hydroxybutyrate)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Unsaturated and epoxy fatty acid estolides were synthesized from the omega and omega-1 hydroxy fatty acids derived from sophorolipids (SLs) prepared by fermentation from glucose:soybean oil and glucose:oleic acid, respectively. These estolides were utilized as additives in solution-cast poly(3-hydro...

  17. Poly(hydroxyalkanoate) Biosynthesis from Crude Alaskan Pollock (Theragra chalcogramma) Oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Six strains of Pseudomonas were tested for their abilities to synthesize poly(hydroxyalkanoate) (PHA) polymers from crude Pollock oil, a large volume byproduct of the Alaskan fishing industry. All six strains were found to produce PHA polymers from hydrolyzed Pollock oil with productivities (P; the...

  18. Synthesis and structural dependence of the functional properties of new green fluorescent poly(propyleneamine) dendrimers

    NASA Astrophysics Data System (ADS)

    Grabchev, Ivo; Mokreva, Pavlina; Gancheva, Valeria; Terlemezyan, Levon

    2013-04-01

    Two new green fluorescence poly(propyleneamine) dendrimers from second generation, comprising eight 1,8-naphthalimide signaling units in their periphery have been synthesized and investigated. Тheir photophysical characteristics have been determined in organic solvents of different polarity. Particular attention has been paid to the spectral characteristics of the solid dendrimer films. The photostability of the dendrimers has also been studied.

  19. One step synthesis of C-dots by microwave mediated caramelization of poly(ethylene glycol).

    PubMed

    Jaiswal, Amit; Ghosh, Siddhartha Sankar; Chattopadhyay, Arun

    2012-01-11

    A rapid, simple and one step microwave mediated method for synthesizing C-dots using poly(ethylene glycol) (PEG) as a precursor and passivating agent is reported. The C-dots possessed low cytotoxicity, were amenable to separation by electrophoresis, photostable and entered cancer cells, making them suitable candidates for bioimaging and biolabelling. PMID:22075768

  20. Sustained Drug Release on Temperature-Responsive Poly(N-isopropylacrylamide)-Integrated Hydroxyapatite

    SciTech Connect

    Shin, Yongsoon ); Liu, Jun; Chang, Jeong H.; Exarhos, Gregory J. )

    2002-01-01

    A hybrid temperature-responsive hydroxyapatite-poly(N-isopropylacrylamide) (HAP-PNIPAAm) gel has been synthesized by the interpenetration of PNIPAAm into a sintered HAP disk through a radical-initiated polymerization of NIPAAm monomers under N2 atmosphere, and shows sustained positive thermo-responsive drug release profile over a month at PBS buffer.

  1. Cloning and Expression of Poly(hydroxyalkanoate) Synthase Genes from Photosynthetic bacterium Allochromatium vinosum ATCC 35206

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(hydroxyalkanoate) (PHA) synthases catalyze the polymerization of beta-hydroxy fatty acids to form PHA biopolyesters. These enzymes are grouped into four classes (classes I to IV) based on their subunit composition and substrate specificity. Since PHA biopolymers are naturally synthesized by b...

  2. Synthesis of biocompatible poly(ɛ-caprolactone)- block-poly(propylene adipate) copolymers appropriate for drug nanoencapsulation in the form of core-shell nanoparticles

    PubMed Central

    Nanaki, Stavroula G; Pantopoulos, Kostas; Bikiaris, Dimitrios N

    2011-01-01

    Poly(propylene adipate)-block-poly(ɛ-caprolactone) copolymers were synthesized using a combination of polycondensation and ring-opening polymerization of ɛ-caprolactone in the presence of poly(propylene adipate). Gel permeation chromatography was used for molecular weight determination, whereas hydrogen-1 nuclear magnetic resonance and carbon-13 nuclear magnetic resonance spectroscopy were employed for copolymer characterization and composition evaluation. The copolymers were found to be block while their composition was similar to the feeding ratio. They formed semicrystalline structures, while only poly(ɛ-caprolactone) formed crystals, as shown by wide angle X-ray diffraction. Differential scanning calorimetry data suggest that the melting point and heat of fusion of copolymers decreased by increasing the poly(propylene adipate) amount. The synthesized polymers exhibited low cytotoxicity and were used to encapsulate desferrioxamine, an iron-chelating drug. The desferrioxamine nanoparticles were self-assembled into core shell structures, had mean particle size <250 nm, and the drug remained in crystalline form. Further studies revealed that the dissolution rate was mainly related to the melting temperature, as well as to the degree of crystallinity of copolymers. PMID:22162656

  3. Biodegradable poly(ether ester urethane)urea elastomers based on poly(ether ester) triblock copolymers and putrescine: synthesis, characterization and cytocompatibility.

    PubMed

    Guan, Jianjun; Sacks, Michael S; Beckman, Eric J; Wagner, William R

    2004-01-01

    Polymers with elastomeric mechanical properties, tunable biodegradation properties and cytocompatibility would be desirable for numerous biomedical applications. Toward this end a series of biodegradable poly(ether ester urethane)urea elastomers (PEEUUs) based on poly(ether ester) triblock copolymers were synthesized and characterized. Poly(ether ester) triblock copolymers were synthesized by ring-opening polymerization of epsilon-caprolactone with polyethylene glycol (PEG). PEEUUs were synthesized from these triblock copolymers and butyl diisocyanate, with putrescine as a chain extender. PEEUUs exhibited low glass transition temperatures and possessed tensile strengths ranging from 8 to 20MPa and breaking strains from 325% to 560%. Increasing PEG length or decreasing poly(caprolactone) length in the triblock segment increased PEEUU water absorption and biodegradation rate. Human umbilical vein endothelial cells cultured in a medium supplemented with PEEUU biodegradation solution suggested a lack of degradation product cytotoxicity. Endothelial cell adhesion to PEEUUs was less than 60% of tissue culture polystyrene and was inversely related to PEEUU hydrophilicity. Surface modification of PEEUUs with ammonia gas radio-frequency glow discharge and subsequent immobilization of the cell adhesion peptide Arg-Gly-Asp-Ser increased endothelial adhesion to a level equivalent to tissue culture polystyrene. These biodegradable PEEUUs thus possessed properties that would be amenable to applications where high strength and flexibility would be desirable and exhibited the potential for tuning with appropriate triblock segment selection and surface modification. PMID:14580912

  4. Poly(carbonate–amide)s Derived from Bio-Based Resources: Poly(ferulic acid-co-tyrosine)

    PubMed Central

    2015-01-01

    Ferulic acid (FA), a bio-based resource found in fruits and vegetables, was coupled with a hydroxyl-amino acid to generate a new class of monomers to afford poly(carbonate–amide)s with potential to degrade into natural products. l-Serine was first selected as the hydroxyl-amino partner for FA, from which the activated p-nitrophenyl carbonate monomer was synthesized. Unfortunately, polymerizations were unsuccessful, and the elimination product was systematically obtained. To avoid elimination, we revised our strategy and used l-tyrosine ethyl ester, which lacks an acidic proton on the α position of the ethyl ester. Four new monomers were synthesized and converted into the corresponding poly(carbonate–amide)s with specific regioselectivities. The polymers were fully characterized through thermal and spectroscopic analyses. Preliminary fluorescent studies revealed interesting photophysical properties for the monomers and their corresponding poly(carbonate–amide)s, beyond the fluorescence characteristics of l-tyrosine and FA, making these materials potentially viable for sensing and/or imaging applications, in addition to their attractiveness as engineering materials derived from renewable resources. PMID:24839309

  5. Water structure and blood compatibility of poly(tetrahydrofurfuryl acrylate).

    PubMed

    Mochizuki, Akira; Hatakeyama, Tatsuko; Tomono, Yuka; Tanaka, Masaru

    2009-01-01

    We previously reported that poly(2-methoxyethyl acrylate) (PMEA), which has excellent blood compatibility, contains a large amount of freezing bound water. In order to confirm the role of freezing bound water in determining blood compatibility, poly(tetrahydrofurfuryl acrylate) (PTHFA) was newly synthesized and the thermal properties of water in PTHFA were investigated by differential scanning calorimetry (DSC), as freezing bound water was observed as cold crystallization in DSC heating curves. In addition, the blood compatibility of PTHFA, including activations of platelets, the coagulation system and the complement system, was investigated. The temperature of cold crystallization of water in PTHFA was higher than that of water in PMEA; moreover, the amount of freezing bound water in PTHFA was smaller than that in PMEA. The effect of freezing bound water on blood compatibility was investigated by comparing PTHFA, PMEA, poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-methoxyethyl methacrylate) (PMEMA). The latter two samples showed no cold crystallization. Activations of platelets, the coagulation system and the complement system were enhanced in the following order: PMEA < PHEMA < PTHFA < PMEMA, PMEA < PMEMA < PTHFA < PHEMA and PMEA < PTHFA < PMEMA < PHEMA, respectively. The above results were reasonably explained by the amount and/or the stability of freezing bound water. PMID:19323878

  6. Mitigated reactive oxygen species generation leads to an improvement of cell proliferation on poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] functionalized polydimethylsiloxane surfaces.

    PubMed

    Yu, Ling; Shi, ZhuanZhuan; Gao, LiXia; Li, ChangMing

    2015-09-01

    In vitro cell-based analysis is strongly affected by material's surface chemical properties. The cell spreading, migration, and proliferation on a substrate surface are initiated and controlled by successful adhesion, particularly for anchor-dependent cells. Unfortunately, polydimethylsiloxane (PDMS), one of the most used polymeric materials for construction of microfluidic and miniaturized biomedical analytic devices, is not a cell-friendly surface because of its inherent hydrophobic property. Herein, a poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] (poly(GMA-co-pEGMA)) polymer brush was synthesized on a PDMS surface through a surface-initiated atom-transfer radical polymerization method. Contact angle and Fourier transform infrared characterization show that the poly (GMA-co-pEGMA) polymer brush functionalization can increase wettability of PDMS and introduce epoxy, hydroxyl, and ether groups into PDMS surface. In vitro cell growth assay demonstrates that cell adhesion and proliferation on poly(GMA-co-pEGMA) polymer brush-functionalized PDMS (poly(GMA-co-pEGMA)@PDMS) are better than on pristine PDMS. Additionally, immobilization of collagen type I (CI) and fibronectin (FN) on poly(GMA-co-pEGMA)@PDMS is better than direct coating of CI and FN on pristine PDMS to promote cell adhesion. Furthermore, increased intracellular reactive oxygen species and cell mitochondrial membrane depolarization, two indicators of cell oxidative stress, are observed from cells growing on pristine PDMS, but not from those on poly(GMA-co-pEGMA)@PDMS. Collectively, we demonstrate that poly(GMA-co-pEGMA) functionalization can enhance cell adhesion and proliferation on PDMS, and thus can be potentially used for microfluidic cell assay devices for cellular physiology study or drug screening. PMID:25711883

  7. Synthese de champs sonores adaptative

    NASA Astrophysics Data System (ADS)

    Gauthier, Philippe-Aubert

    La reproduction de champs acoustiques est une approche physique au probleme technologique de la spatialisation sonore. Cette these concerne l'aspect physique de la reproduction de champs acoustiques. L'objectif principal est l'amelioration de la reproduction de champs acoustiques par "synthese de champs acoustiques" ("Wave Field Synthesis", WFS), une approche connue, basee sur des hypotheses de champ libre, a l'aide du controle actif par l'ajout de capteurs de l'erreur de reproduction et d'une boucle fermee. Un premier chapitre technique (chapitre 4) expose les resultats d'appreciation objective de la WFS par simulations et mesures experimentales. L'effet indesirable de la salle de reproduction sur les qualites objectives de la WFS fut illustre. Une premiere question de recherche fut ensuite abordee (chapitre 5), a savoir s'il est possible de reproduire des champs progressifs en salle dans un paradigme physique de controle actif: cette possibilite fut prouvee. L'approche technique privilegiee, "synthese de champs adaptative" ("Adaptive Wave Field Synthesis" [AWFS]), fut definie, puis simulee (chapitre 6). Cette approche d'AWFS comporte une originalite en controle actif et en reproduction de champs acoustiques: la fonction cout quadratique representant la minimisation des erreurs de reproduction inclut une regularisation de Tikhonov avec solution a priori qui vient de la WFS. L'etude de l'AWFS a l'aide de la decomposition en valeurs singulieres (chapitre 7) a permis de comprendre les mecanismes propres a l'AWFS. C'est la deuxieme principale originalite de la these. L'algorithme FXLMS (LMS et reference filtree) est modifie pour l'AWFS (chapitre 8). Le decouplage du systeme par decomposition en valeurs singulieres est illustre dans le domaine du traitement de signal et l'AWFS basee sur le controle independant des modes de rayonnement est simulee (chapitre 8). Ce qui constitue la troisieme originalite principale de cette these. Ces simulations du traitement de signal

  8. Effect of heat shock on poly(ADP-ribose) synthetase and DNA repair in Drosophila cells

    SciTech Connect

    Nolan, N.L.; Kidwell, W.R.

    1982-04-01

    Poly(ADP-ribose) synthetase, a chromatin-bound enzyme which attaches polyanionic chains of ADP-ribose to nuclear proteins, was found to be temperature sensitive in intact Drosophila melanogaster cells. The synthetase was completely inactivated by heat-shocking the cells at 37/sup 0/C for 5 min, a condition which had no appreciable effect on the subsequent growth of Drosophila cells at their physiological temperature. The heat-shock effect on synthetase was reversible; enzyme activity began to reappear about 2 hr post heat shock. During the 2-hr interval when poly(ADP-ribose) synthetase was absent, the cells were competent in repair of ..gamma..-ray-induced DNA strand breaks as shown by DNA sedimentation studies on alkaline sucrose gradients. It is thus concluded that poly(ADP-ribose) synthesis is unnecessary for repair of DNA strand breaks introduced by irradiation. The same conclusion was reached from the fact that two inhibitors of poly(ADP-ribose) synthetase 3-aminobenzamide and 5-methylnicotinamide, failed to block repair of ..gamma..-ray-induced DNA chain breaks even though both inhibitors reduced the amount of poly(ADP-ribose) synthesized in cells by 50-75%. Although it was found that the repair of DNA strand breaks is independent of poly(ADP-ribose) synthesis, irradiation does activate the synthetase in control cells, as shown by radioimmunoassay of poly(ADP-ribose) levels.

  9. PolyMetformin combines carrier and anticancer activities for in vivo siRNA delivery

    PubMed Central

    Zhao, Yi; Wang, Wei; Guo, Shutao; Wang, Yuhua; Miao, Lei; Xiong, Yang; Huang, Leaf

    2016-01-01

    Metformin, a widely implemented anti-diabetic drug, exhibits potent anticancer efficacies. Herein a polymeric construction of Metformin, PolyMetformin (PolyMet) is successfully synthesized through conjugation of linear polyethylenimine (PEI) with dicyandiamide. The delocalization of cationic charges in the biguanide groups of PolyMet reduces the toxicity of PEI both in vitro and in vivo. Furthermore, the polycationic properties of PolyMet permits capture of siRNA into a core-membrane structured lipid-polycation-hyaluronic acid (LPH) nanoparticle for systemic gene delivery. Advances herein permit LPH-PolyMet nanoparticles to facilitate VEGF siRNA delivery for VEGF knockdown in a human lung cancer xenograft, leading to enhanced tumour suppressive efficacy. Even in the absence of RNAi, LPH-PolyMet nanoparticles act similarly to Metformin and induce antitumour efficacy through activation of the AMPK and inhibition of the mTOR. In essence, PolyMet successfully combines the intrinsic anticancer efficacy of Metformin with the capacity to carry siRNA to enhance the therapeutic activity of an anticancer gene therapy. PMID:27264609

  10. Reduction biodegradable brushed PDMAEMA derivatives synthesized by atom transfer radical polymerization and click chemistry for gene delivery.

    PubMed

    Liu, Jia; Xu, Yanglin; Yang, Qizhi; Li, Cao; Hennink, Wim E; Zhuo, Renxi; Jiang, Xulin

    2013-08-01

    Novel reducible and degradable brushed poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) derivatives were synthesized and evaluated as non-viral gene delivery vectors. First, alkyne-functionalized poly(aspartic acid) with a disulfide linker between the propargyl group and backbone poly([(propargyl carbamate)-cystamine]-α,β-aspartamide) (P(Asp-SS-AL)) was synthesized. Second, linear low molecular weight (LMW) monoazido-functionalized PDMAEMAs synthesized via atom transfer radical polymerization were conjugated to the polypeptide side-chains of P(Asp-SS-AL) via click chemistry to yield high molecular weight (HMW) polyaspartamide-based disulfide-containing brushed PDMAEMAs (PAPDEs). The PAPDEs were able to condense plasmid DNA to form 100 to 200nm polyplexes with positive ζ-potentials. Moreover, in the presence of dithiothreitol the PAPDEs degraded into LMW PDAMEMA, resulting in disintegration of the PAPDE/DNA polyplexes and subsequent release of plasmid DNA. In vitro experiments revealed that the PAPDEs were less cytotoxic and more effective in gene transfection than control 25kDa poly(ethyleneimine) and HMW linear PDMAEMA. In conclusion, reducible and degradable polycations composed of LMW PDMAEMAs coupled to a polypeptide backbone via reduction-sensitive disulfide bonds are effective gene vectors with an excellent cytocompatibility. PMID:23660547

  11. Synthesizing Diamond from Liquid Feedstock

    NASA Technical Reports Server (NTRS)

    Tzeng, Yonhua

    2005-01-01

    A relatively economical method of chemical vapor deposition (CVD) has been developed for synthesizing diamond crystals and films. Unlike prior CVD methods for synthesizing diamond, this method does not require precisely proportioned flows of compressed gas feedstocks or the use of electrical discharges to decompose the feedstocks to obtain free radicals needed for deposition chemical reactions. Instead, the feedstocks used in this method are mixtures of common organic liquids that can be prepared in advance, and decomposition of feedstock vapors is effected simply by heating. The feedstock used in this method is a solution comprising between 90 and 99 weight percent of methanol and the balance of one or more other oxyhydrocarbons that could include ethanol, isopropanol, and/or acetone. This mixture of compounds is chosen so that dissociation of molecules results in the desired proportions of carbon-containing radicals (principally, CH3) and of OH, H, and O radicals. Undesirably, the CVD temperature and pressure conditions thermodynamically favor the growth of graphite over the growth of diamond. The H radicals are desirable because they help to stabilize the growing surface of diamond by shifting the thermodynamic balance toward favoring the growth of diamond. The OH and O radicals are desirable because they preferentially etch graphite and other non-diamond carbon, thereby helping to ensure the net deposition of pure diamond. The non-methanol compounds are included in the solution because (1) methanol contains equal numbers of C and O atoms; (2) an excess of C over O is needed to obtain net deposition of diamond; and (3) the non-methanol molecules contain multiple carbon atoms for each oxygen atom and thus supply the needed excess carbon A typical apparatus used in this method includes a reservoir containing the feedstock liquid and a partially evacuated stainless-steel reaction chamber. The reservoir is connected to the chamber via tubing and a needle valve or

  12. Balanced Ambipolar Poly(diketopyrrolopyrrole-alt-tetrafluorobenzene) Semiconducting Polymers Synthesized via Direct Arylation Polymerization.

    PubMed

    Wang, Kai; Wang, Guojie; Wang, Mingfeng

    2015-12-01

    The synthesis of an ambipolar π-conjugated copolymer consisting of alternating diketopyrrolopyrrole and tetrafluorobenzene via direct arylation polymerization (DAP) is reported. Two different combinations of monomers are investigated under various catalytic conditions for DAP. The target polymer obtained under an optimized catalytic condition shows minimal structural defects, a number-average molecular weight of 33.2 kDa, and balanced electron and hole mobility of 1 × 10(-2) cm(2) V(-1) S(-1) in the organic field-effect transistors fabricated and tested under ambient conditions. PMID:26421942

  13. Preparation of graphene oxide/poly (3,4-ethylenedioxytriophene): Poly (styrene sulfonate) (PEDOT:PSS) electrospun nanofibers

    NASA Astrophysics Data System (ADS)

    Efelina, Vita; Widianto, Eri; Rusdiana, Dadi; Nugroho, A. A.; Kusumaatmaja, Ahmad; Triyana, Kuwat; Santoso, Iman

    2016-04-01

    Graphene oxide (GO)/Poly (3,4-Ethylenedioxytriophene):Poly (styrene Sulfonate) (PEDOT:PSS) nanofibers have been successfully fabricated by a simple electrospinning technique to develop conductive nanofibers with polyvinyl alcohol (PVA) act as a carrier solution. Graphene oxide has been synthesized by Hummer's method and has been confirmed by Raman Spectroscopy, FTIR and UV-Vis Spectroscopy. GO/PEDOT:PSS composite nanofibers. The structural and morphological properties were characterized by Scanning Electron Microscopy (SEM). The result of SEM show that GO/PEDOT:PSS nanofibers has a relatively uniform morphology nanofiber with diameter between 180 nm - 340 nm with smooth nanofiber surface. The produced nanofibers from this study can be utilized for various applications such as flexible, conductive and transparent electrode.

  14. Preparation of graphene oxide/poly (3,4-ethylenedioxytriophene): Poly (styrene sulfonate) (PEDOT:PSS) electrospun nanofibers

    NASA Astrophysics Data System (ADS)

    Widianto, Eri; Efelina, Vita; Rusdiana, Dadi; Nugroho, A. A.; Kusumaatmaja, Ahmad; Triyana, Kuwat; Santoso, Iman

    2016-04-01

    Graphene oxide (GO)/Poly (3,4-Ethylenedioxytriophene):Poly (styrene Sulfonate) (PEDOT:PSS)nanofibers have been successfully fabricated by a simple electrospinning technique to develop conductive nanofibers with polyvinyl alcohol (PVA) act as a carrier solution. Graphene oxide hasbeen synthesized by Hummer's method and has been confirmed by Raman Spectroscopy, FTIR, and UV-Vis Spectroscopy. The structural and morphological properties of GO/PEDOT:PSS composite nanofiberswere characterized by Scanning Electron Microscopy (SEM). The result of SEM showed that GO/PEDOT:PSS nanofibers have a relatively uniform morphology nanofiber with adiameterof 180 nm - 340 nm with smooth nanofiber surface. The produced nanofibers from this study can be utilized for various applicationssuch as aflexible, conductive and transparent electrode.

  15. Preparation and evaluation of poly(ethylene glycol)-poly(lactide) micelles as nanocarriers for oral delivery of cyclosporine a.

    PubMed

    Zhang, Yanhui; Li, Xinru; Zhou, Yanxia; Wang, Xiaoning; Fan, Yating; Huang, Yanqing; Liu, Yan

    2010-01-01

    A series of monomethoxy poly(ethylene glycol)-poly(lactide) (mPEG-PLA) diblock copolymers were designed according to polymer-drug compatibility and synthesized, and mPEG-PLA micelle was fabricated and used as a nanocarrier for solubilization and oral delivery of Cyclosporine A (CyA). CyA was efficiently encapsulated into the micelles with nanoscaled diameter ranged from 60 to 96 nm with a narrow size distribution. The favorable stabilities of CyA-loaded polymeric micelles were observed in simulated gastric and intestinal fluids. The in vitro drug release investigation demonstrated that drug release was retarded by polymeric micelles. The enhanced intestinal absorption of CyA-loaded polymeric micelles, which was comparable to the commercial formulation of CyA (Sandimmun Neoral®), was found. These suggested that polymeric micelles might be an effective nanocarrier for solubilization of poorly soluble CyA and further improving oral absorption of the drug. PMID:20671795

  16. Preparation and Evaluation of Poly(Ethylene Glycol)-Poly(Lactide) Micelles as Nanocarriers for Oral Delivery of Cyclosporine A

    NASA Astrophysics Data System (ADS)

    Zhang, Yanhui; Li, Xinru; Zhou, Yanxia; Wang, Xiaoning; Fan, Yating; Huang, Yanqing; Liu, Yan

    2010-06-01

    A series of monomethoxy poly(ethylene glycol)-poly(lactide) (mPEG-PLA) diblock copolymers were designed according to polymer-drug compatibility and synthesized, and mPEG-PLA micelle was fabricated and used as a nanocarrier for solubilization and oral delivery of Cyclosporine A (CyA). CyA was efficiently encapsulated into the micelles with nanoscaled diameter ranged from 60 to 96 nm with a narrow size distribution. The favorable stabilities of CyA-loaded polymeric micelles were observed in simulated gastric and intestinal fluids. The in vitro drug release investigation demonstrated that drug release was retarded by polymeric micelles. The enhanced intestinal absorption of CyA-loaded polymeric micelles, which was comparable to the commercial formulation of CyA (Sandimmun Neoral®), was found. These suggested that polymeric micelles might be an effective nanocarrier for solubilization of poorly soluble CyA and further improving oral absorption of the drug.

  17. Hyperproduction of poly(4-hydroxybutyrate) from glucose by recombinant Escherichia coli

    PubMed Central

    2012-01-01

    Background Poly(4-hydroxybutyrate) [poly(4HB)] is a strong thermoplastic biomaterial with remarkable mechanical properties, biocompatibility and biodegradability. However, it is generally synthesized when 4-hydroxybutyrate (4HB) structurally related substrates such as γ-butyrolactone, 4-hydroxybutyrate or 1,4-butanediol (1,4-BD) are provided as precursor which are much more expensive than glucose. At present, high production cost is a big obstacle for large scale production of poly(4HB). Results Recombinant Escherichia coli strain was constructed to achieve hyperproduction of poly(4-hydroxybutyrate) [poly(4HB)] using glucose as a sole carbon source. An engineering pathway was established in E. coli containing genes encoding succinate degradation of Clostridium kluyveri and PHB synthase of Ralstonia eutropha. Native succinate semialdehyde dehydrogenase genes sad and gabD in E. coli were both inactivated to enhance the carbon flux to poly(4HB) biosynthesis. Four PHA binding proteins (PhaP or phasins) including PhaP1, PhaP2, PhaP3 and PhaP4 from R. eutropha were heterologously expressed in the recombinant E. coli, respectively, leading to different levels of improvement in poly(4HB) production. Among them PhaP1 exhibited the highest capability for enhanced polymer synthesis. The recombinant E. coli produced 5.5 g L-1 cell dry weight containing 35.4% poly(4HB) using glucose as a sole carbon source in a 48 h shake flask growth. In a 6-L fermentor study, 11.5 g L-1 cell dry weight containing 68.2% poly(4HB) was obtained after 52 h of cultivation. This was the highest poly(4HB) yield using glucose as a sole carbon source reported so far. Poly(4HB) was structurally confirmed by gas chromatographic (GC) as well as 1H and 13C NMR studies. Conclusions Significant level of poly(4HB) biosynthesis from glucose can be achieved in sad and gabD genes deficient strain of E. coli JM109 harboring an engineering pathway encoding succinate degradation genes and PHB synthase gene

  18. Advanced poly-LED displays

    NASA Astrophysics Data System (ADS)

    Childs, Mark; Nisato, Giovanni; Fish, D.; Giraldo, Andrea; Jenkins, A. J.; Johnson, Mark T.

    2003-05-01

    Philips have been actively developing polymer OLED (poly-LED) displays as a future display technology. Their emissive nature leads to a very attractive visual appearance, with wide viewing angle, high brightness and fast response speed. Whilst the first generation of poly-LED displays are likely to be passive-matrix driven, power reduction and resolution increase will lead to the use of active-matrix poly-LED displays. Philips Research have designed, fabricated and characterized five different designs of active-matrix polymer-LED display. Each of the five displays makes use of a distinct pixel programming- or pixel drive-technique, including current programming, threshold voltage measurement and photodiode feedback. It will be shown that hte simplest voltage-programmed current-source pixel suffers from potentially unacceptable brightness non-uniformity, and that advanced pixel circuits can provide a solution to this. Optical-feedback pixel circuits will be discussed, showing that they can be used to improve uniformity and compensate for image burn-in due to polymer-LED material degradation, improving display lifetime. Philips research has also been active in developing technologies required to implement poly-LED displays on flexible substrates, including materials, processing and testing methods. The fabrication of flexible passive-matrix poly-LED displays will be presented, as well as the ongoing work to assess the suitability of processing flexible next-generation poly-LED displays.

  19. Poly-instanton inflation

    NASA Astrophysics Data System (ADS)

    Cicoli, Michele; Pedro, Francisco G.; Tasinato, Gianmassimo

    2011-12-01

    We propose a new inflationary scenario in type IIB Calabi-Yau compactifications, where the inflaton is a Kähler modulus parameterising the volume of an internal four-cycle. The inflaton potential is generated via poly-instanton corrections to the superpotential which give rise to a naturally flat direction due to their double exponential suppression. Given that the volume mode is kept stable during inflation, all the inflaton-dependent higher dimensional operators are suppressed. Moreover, string loop effects can be shown to be negligible throughout all the inflationary dynamics for natural values of the underlying parameters. The model is characterised by a reheating temperature of the order Trh simeq 106 GeV which requires Ne simeq 54 e-foldings of inflation. All the inflationary observables are compatible with current observations since the spectral index is ns simeq 0.96, while the tensor-to-scalar ratio is r simeq 10-5. The volume of the Calabi-Yau is of order 103 in string units, corresponding to an inflationary scale around 1015 GeV.

  20. Poly-instanton inflation

    SciTech Connect

    Cicoli, Michele; Pedro, Francisco G.; Tasinato, Gianmassimo E-mail: f.pedro1@physics.ox.ac.uk

    2011-12-01

    We propose a new inflationary scenario in type IIB Calabi-Yau compactifications, where the inflaton is a Kähler modulus parameterising the volume of an internal four-cycle. The inflaton potential is generated via poly-instanton corrections to the superpotential which give rise to a naturally flat direction due to their double exponential suppression. Given that the volume mode is kept stable during inflation, all the inflaton-dependent higher dimensional operators are suppressed. Moreover, string loop effects can be shown to be negligible throughout all the inflationary dynamics for natural values of the underlying parameters. The model is characterised by a reheating temperature of the order T{sub rh} ≅ 10{sup 6} GeV which requires N{sub e} ≅ 54 e-foldings of inflation. All the inflationary observables are compatible with current observations since the spectral index is n{sub s} ≅ 0.96, while the tensor-to-scalar ratio is r ≅ 10{sup −5}. The volume of the Calabi-Yau is of order 10{sup 3} in string units, corresponding to an inflationary scale around 10{sup 15} GeV.

  1. Synthesis and self-assembly of poly(3-hexylthiophene)-block-poly(acrylic acid)

    SciTech Connect

    Li, Zicheng; Ono, Robert J.; Wu, Zong-Quan; Bielawski, Christopher W.

    2011-01-01

    A modular and convenient synthesis of ethynyl end functionalized poly(3-hexylthiophene) in high purity is reported; this material facilitated access to poly(3-hexylthiophene)-block-poly(acrylic acid) which self-assembled into hierarchical structures.

  2. Cellular behaviour of hepatocyte-like cells from nude mouse bone marrow-derived mesenchymal stem cells on galactosylated poly(D,L-lactic-co-glycolic acid).

    PubMed

    Roh, Hyun; Yang, Dae Hyeok; Chun, Heung Jae; Khang, Gilson

    2015-07-01

    Previously, the galactosylation of poly(d,l-lactic-co-glycolic acid) (PLGA) surface was accomplished by grafting allylamine (AA), using inductively coupled plasma-assisted chemical vapour deposition (ICP-CVD) and conjugating lactobionic acid (LA) with AA via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide (EDC/NHS) activation for hepatic tissue-engineering purposes. As a continuation study, the cellular behaviour of hepatocyte-like cells (HLCs) on the surface of the galactosylated PLGA were investigated. Nude mouse bone marrow-derived mesenchymal stem cells (MSCs) were cultured under hepatogenic conditions and the differentiated cells were characterized by reverse-transcription polymerase chain reaction (RT-PCR), immunofluorescence and periodic acid-Schiff (PAS) staining. Galactosylated PLGA enhanced the proliferation rate of HLCs compared to the control; HLCs on the surface of the sample became aggregated and formed spheroids after 3 days of culture. A large number of cells on the surface of the sample exhibited increased liver-specific functional activities, such as albumin and urea secretions. In addition, multicellular spheroids in the sample strongly expressed phospholyated focal adhesion kinase (pFAK) (cell-matrix interactions), E-cadherin (cell-cell interactions) and connexin 32 (Cox32; gap junction). PMID:23784953

  3. Length heteroplasmy of the polyC-polyT-polyC stretch in the dog mtDNA control region.

    PubMed

    Verscheure, Sophie; Backeljau, Thierry; Desmyter, Stijn

    2015-09-01

    Previously, the mitochondrial control region of 214 Belgian dogs was sequenced. Analysis of this data indicated length heteroplasmy of the polyT stretch in the polyC-polyT-polyC stretch from positions 16661 to 16674. Nine polyC-polyT-polyC haplotype combinations were observed, consisting of seven major haplotypes (highest signal intensity) combined with minor haplotypes (lower signal intensity) one T shorter than the major haplotype in all but three dogs. The longer the polyT stretch, the smaller was the difference in signal intensity between the major and minor haplotype peaks. Additional sequencing, cloning, and PCR trap experiments were performed to further study the intra-individual variation of this mitochondrial DNA (mtDNA) region. Cloning experiments demonstrated that the proportion of clones displaying the minor haplotypes also increased with the length of the polyT stretch. Clone amplification showed that in vitro polymerase errors might contribute to the length heteroplasmy of polyT stretches with at least 10 Ts. Although major and minor polyC-polyT-polyC haplotypes did not differ intra-individually within and between tissues in this study, interpretation of polyT stretch variation should be handled with care in forensic casework. PMID:25394743

  4. Poly(cyclohexylethylene)-block-Poly(lactide) Oligomers for Ultrasmall Nanopatterning Using Atomic Layer Deposition.

    PubMed

    Yao, Li; Oquendo, Luis E; Schulze, Morgan W; Lewis, Ronald M; Gladfelter, Wayne L; Hillmyer, Marc A

    2016-03-23

    Poly(cyclohexylethylene)-block-poly(lactide) (PCHE-PLA) block polymers were synthesized through a combination of anionic polymerization, heterogeneous catalytic hydrogenation and controlled ring-opening polymerization. Ordered thin films of PCHE-PLA with ultrasmall hexagonally packed cylinders oriented perpendicularly to the substrate surface were prepared by spin-coating and subsequent solvent vapor annealing for use in two distinct templating strategies. In one approach, selective hydrolytic degradation of the PLA domains generated nanoporous PCHE templates with an average pore diameter of 5 ± 1 nm corroborated by atomic force microscopy and grazing incidence small-angle X-ray scattering. Alternatively, sequential infiltration synthesis (SIS) was employed to deposit Al2O3 selectively into the PLA domains of PCHE-PLA thin films. A combination of argon ion milling and O2 reactive ion etching (RIE) enabled the replication of the Al2O3 nanoarray from the PCHE-PLA template on diverse substrates including silicon and gold with feature diameters less than 10 nm. PMID:26954771

  5. Delivery of phytochemical thymoquinone using molecular micelle modified poly(D, L lactide-co-glycolide) (PLGA) nanoparticles

    NASA Astrophysics Data System (ADS)

    Ganea, Gabriela M.; Fakayode, Sayo O.; Losso, Jack N.; van Nostrum, Cornelus F.; Sabliov, Cristina M.; Warner, Isiah M.

    2010-07-01

    Continuous efforts have been made in the development of potent benzoquinone-based anticancer drugs aiming for improved water solubility and reduced adverse reactions. Thymoquinone is a liposoluble benzoquinone-based phytochemical that has been shown to have remarkable antioxidant and anticancer activities. In the study reported here, thymoquinone-loaded PLGA nanoparticles were synthesized and evaluated for physico-chemical, antioxidant and anticancer properties. The nanoparticles were synthesized by an emulsion solvent evaporation method using anionic molecular micelles as emulsifiers. The system was optimized for maximum entrapment efficiency using a Box-Behnken experimental design. Optimum conditions were found for 100 mg PLGA, 15 mg TQ and 0.5% w/v poly(sodium N-undecylenyl-glycinate) (poly-SUG). In addition, other structurally related molecular micelles such as poly(sodium N-heptenyl-glycinate) (poly-SHG), poly(sodium N-undecylenyl-leucinate) (poly-SUL), and poly(sodium N-undecylenyl-valinate) (poly-SUV) were also examined as emulsifiers. All investigated molecular micelles provided excellent emulsifier properties, leading to maximum optimized TQ entrapment efficiency, and monodispersed particle sizes below 200 nm. The release of TQ from molecular micelle modified nanoparticles was investigated by dialysis and reached lower levels than the free drug. The antioxidant activity of TQ-loaded nanoparticles, indicated by IC50 (mg ml - 1 TQ for 50% 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity), was highest for poly-SUV emulsified nanoparticles (0.030 ± 0.002 mg ml - 1) as compared to free TQ. In addition, it was observed that TQ-loaded nanoparticles emulsified with poly-SUV were more effective than free TQ against MDA-MB-231 cancer cell growth inhibition, presenting a cell viability of 16.0 ± 5.6% after 96 h.

  6. Vault-poly-ADP-ribose polymerase in the Octopus vulgaris brain: a regulatory factor of actin polymerization dynamic.

    PubMed

    De Maio, Anna; Natale, Emiliana; Rotondo, Sergio; Di Cosmo, Anna; Faraone-Mennella, Maria Rosaria

    2013-09-01

    Our previous behavioural, biochemical and immunohistochemical analyses conducted in selected regions (supra/sub oesophageal masses) of the Octopus vulgaris brain detected a cytoplasmic poly-ADP-ribose polymerase (more than 90% of total enzyme activity). The protein was identified as the vault-free form of vault-poly-ADP-ribose polymerase. The present research extends and integrates the biochemical characterization of poly-ADP-ribosylation system, namely, reaction product, i.e., poly-ADP-ribose, and acceptor proteins, in the O. vulgaris brain. Immunochemical analyses evidenced that the sole poly-ADP-ribose acceptor was the octopus cytoskeleton 50-kDa actin. It was present in both free, endogenously poly-ADP-ribosylated form (70kDa) and in complex with V-poly-ADP-ribose polymerase and poly-ADP-ribose (260kDa). The components of this complex, alkali and high salt sensitive, were purified and characterized. The kind and the length of poly-ADP-ribose corresponded to linear chains of 30-35 ADP-ribose units, in accordance with the features of the polymer synthesized by the known vault-poly-ADP-ribose polymerase. In vitro experiments showed that V-poly-ADP-ribose polymerase activity of brain cytoplasmic fraction containing endogenous actin increased upon the addition of commercial actin and was highly reduced by ATP. Anti-actin immunoblot of the mixture in the presence and absence of ATP showed that the poly-ADP-ribosylation of octopus actin is a dynamic process balanced by the ATP-dependent polymerization of the cytoskeleton protein, a fundamental mechanism for synaptic plasticity. PMID:23831359

  7. In vitro and in vivo safety evaluation of biodegradable self-assembled monomethyl poly (ethylene glycol)-poly (ε-caprolactone)-poly (trimethylene carbonate) micelles.

    PubMed

    Yang, Xi; Cao, Dan; Wang, Ning; Sun, Lu; Li, Ling; Nie, Shihong; Wu, Qinjie; Liu, Xinyu; Yi, Cheng; Gong, Changyang

    2014-01-01

    Safety evaluation of self-assembled polymeric micelles is important for biomedical involvement in drug delivery systems in the future. In this study, biodegradable monomethyl poly (ethylene glycol)-poly (ε-caprolactone)-poly (trimethylene carbonate) [MPEG-P(CL-co-TMC)] copolymer was synthesized and characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance analysis, and gel permeation chromatography. MPEG-P(CL-co-TMC) micelles were prepared by self-assembly without any organic solvent. The present study was conducted to assess the safety of blank MPEG-P(CL-co-TMC) micelles both in vitro and in vivo. Particle size (30.09 ± 0.06 nm) and zeta potential (0.067 ± 0.027 mV) of obtained micelles were determined by Malvern laser particle size analyzer. The results of in vitro toxicity evaluation implied that the prepared micelles did not cause hemolysis or severely cell toxicity. Meanwhile, we did not observe any toxic response or histopathological changes in the study of in vivo acute toxicity evaluation and histopathological study of MPEG-P(CL-co-TMC) micelles. In conclusion, the maximal tolerance dose of MPEG-P(CL-co-TMC) micelles (100 mg/mL) by intravenous injection was supposed to be greater than 10 g/kg body weight. Therefore, it might have potential applications in biomedical field. PMID:24282070

  8. Preparation and characterization of tri-block poly(lactide)-poly(ethylene glycol)-poly(lactide) nanogels for controlled release of naltrexone.

    PubMed

    Asadi, H; Rostamizadeh, K; Salari, D; Hamidi, M

    2011-09-15

    Tri-block poly(lactide)-poly(ethylene glycol)-poly(lactide) (PLA-PEG-PLA) copolymers and related acrylated derivative were synthesized and used to prepare micelles and nanogels for controlled release of naltrexone. The resulting copolymers, micelles and nanogels were characterized by various techniques such as proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, fluorescence spectrometry, differential scanning calorimetry, photon correlation spectroscopy and scanning electron microscopy. The nanogels exhibited high encapsulation efficiency around 60% and excellent stability for long periods of time. The drug release profiles of micelles and nanogels were compared and it was found that the naltrexone loaded nanogels offered a steady and long-term release pattern for different periods of time up to 35 days, depending on the crosslinker concentration, compared to the micelles. The size of nanogels could be manipulated easily in the range of 128-200nm by variations in polymer concentration used in the nanogels preparation step. From the results obtained it can be concluded that PLA-PEG-PLA nanogels can be considered as a promising carrier for drug delivery purpose. PMID:21729744

  9. Reversible adsorption of catalase onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogels.

    PubMed

    Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

    2015-05-01

    In this presented study, poly(acrylamide-glycidyl methacrylate) [poly(AAm-GMA)] cryogels were synthesized by cryopolymerization technique at sub-zero temperature. Prepared cryogels were then functionalized with iminodiacetic acid (IDA) and chelated with Fe(3+) ions in order produce the metal chelate affinity matrix. Synthesized cryogels were characterized with FTIR, ESEM and EDX analysis, and it was found that the cryogel had sponge like structure with interconnected pores and their pore diameter was about 200 μm. Fe(3+) chelated poly(AAm-GMA)-IDA cryogels were used for the adsorption of catalase and optimum adsorption conditions were determined by varying the medium pH, initial catalase concentration, temperature and ionic strength. Maximum catalase adsorption onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was found to be 12.99 mg/g cryogel at 25 °C, by using pH 5.0 acetate buffer. Adsorbed catalase was removed from the cryogel by using 1.0M of NaCl solution and desorption yield was found to be 96%. Additionally, reusability profile of the Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was also investigated and it was found that, adsorption capacity of the cryogels didn't decrease significantly at the end of the 40 reuses. Catalase activity studies were also tested and it was demonstrated that desorbed catalase retained 70% of its initial activity. PMID:25746283

  10. Efficient gene transfection using novel cationic polymers poly(hydroxyalkylene imines).

    PubMed

    Zaliauskiene, Lolita; Bernadisiute, Ula; Vareikis, Ausvydas; Makuska, Ricardas; Volungeviciene, Ieva; Petuskaite, Agne; Riauba, Laurynas; Lagunavicius, Arunas; Zigmantas, Sarunas

    2010-09-15

    A series of novel cationic polymers poly(hydroxyalkylene imines) were synthesized and tested for their ability to transfect cells in vitro and in vivo. Poly(hydroxyalkylene imines), in particular, poly(2-hydroxypropylene imine) (pHP), poly(2-hydroxypropylene imine ethylene imine) (pHPE), and poly(hydroxypropylene imine propylene imine) (pHPP) were synthesized by polycondensation reaction from 1,3-diamino-2-propanol and the appropriate dibromide. Electron microscopic examination demonstrated that the resulting polymers condensed DNA into toroid shape complexes of 100-150 nm in size. Transfection studies showed that all three polymers were able to deliver genetic material into the cell, with pHP being superior to pHPP and pHPE. pHP acted as an efficient gene delivery agent in a variety of different cell lines and outcompeted most of the widely used polymer or lipid based transfection reagents. Intravenous administration of pHP-DNA polyplexes in mice followed by the reporter gene analysis showed that the reagent was suitable for in vivo applications. In summary, the results indicate that pHP is a new efficient reagent for gene delivery in vitro and in vivo. PMID:20695432

  11. Overview on poly(ADP-ribose) immuno-biomedicine and future prospects.

    PubMed

    Kanai, Yoshiyuki

    2016-01-01

    Poly(ADP-ribose), identified in 1966 independently by three groups Strassbourg, Kyoto and Tokyo, is synthesized by poly(ADP-ribose) polymerases (PARP) from NAD(+) as a substrate in the presence of Mg(2+). The structure was unique in that it has ribose-ribose linkage. In the early-1970s, however, its function in vivo/in vitro was still controversial and the antibody against it was desired to help clear its significance. Thereupon, the author tried to produce antibody against poly(ADP-ribose) in rabbits and succeeded in it for the first time in the world. Eventually, this success has led to the following two groundbreaking papers in Nature: "Naturally-occurring antibody against poly(ADP-ribose) in patients with autoimmune disease SLE", and "Induction of anti-poly(ADP-ribose) antibody by immunization with synthetic double-stranded RNA, poly(A)·poly(U)".On the way to the publication of the first paper, a reviewer gave me a friendly comment that there is "heteroclitic" fashion as a mechanism of the production of natural antibody. This comment was really a God-send for me, and became a train of power for publication of another paper, as described above. Accordingly, I thought this, I would say, episode is worth describing herein. Because of its importance in biomedical phenomena, a certain number of articles related to "heteroclitic" have become to be introduced in this review, although they were not always directly related to immuno-biological works on poly(ADP-ribose). Also, I tried to speculate on the future prospects of poly(ADP-ribose), product of PARP, as an immuno-regulatory molecule, including either induced or naturally-occurring antibodies, in view of "heteroclitic". PMID:27477457

  12. Controlled synthesis of poly(3-hexylthiophene) in continuous flow

    PubMed Central

    Seyler, Helga; Subbiah, Jegadesan; Jones, David John; Holmes, Andrew Bruce

    2013-01-01

    Summary There is an increasing demand for organic semiconducting materials with the emergence of organic electronic devices. In particular, large-area devices such as organic thin-film photovoltaics will require significant quantities of materials for device optimization, lifetime testing and commercialization. Sourcing large quantities of materials required for the optimization of large area devices is costly and often impossible to achieve. Continuous-flow synthesis enables straight-forward scale-up of materials compared to conventional batch reactions. In this study, poly(3-hexylthiophene), P3HT, was synthesized in a bench-top continuous-flow reactor. Precise control of the molecular weight was demonstrated for the first time in flow for conjugated polymers by accurate addition of catalyst to the monomer solution. The P3HT samples synthesized in flow showed comparable performance to commercial P3HT samples in bulk heterojunction solar cell devices. PMID:23946848

  13. Composites comprising biologically-synthesized nanomaterials

    DOEpatents

    Curran, Seamus; Dias, Sampath; Blau, Werner; Wang, Jun; Oremland, Ronald S; Baesman, Shaun

    2013-04-30

    The present disclosure describes composite materials containing a polymer material and a nanoscale material dispersed in the polymer material. The nanoscale materials may be biologically synthesized, such as tellurium nanorods synthesized by Bacillus selenitireducens. Composite materials of the present disclosure may have optical limiting properties and find use in optical limiting devices.

  14. Pathways to poly-victimization.

    PubMed

    Finkelhor, David; Ormrod, Richard; Turner, Heather; Holt, Melissa

    2009-11-01

    Some children, whom we have labeled poly-victims, experience very high levels of victimizations of different types. This article finds support for a conceptual model suggesting that there may be four distinct pathways to becoming such a poly-victim: (a) residing in a dangerous community, (b) living in a dangerous family, (c) having a chaotic, multiproblem family environment, or (d) having emotional problems that increase risk behavior, engender antagonism, and compromise the capacity to protect oneself. It uses three waves of the Developmental Victimization Survey, a nationally representative sample of children aged 2-17 years. All four hypothesized pathways showed significant independent association with poly-victim onset. For the younger children, the symptom score representing emotional problems was the only significant predictor. For the older children, the other three pathway variables were significant predictors--dangerous communities, dangerous families, and problem families--but not symptom score. Poly-victimization onset was also disproportionately likely to occur in the year prior to children's 7th and 15th birthday, corresponding roughly to the entry into elementary school and high school. The identification of such pathways and the ages of high onset should help practitioners design programs for preventing vulnerable children from becoming poly-victims. PMID:19837972

  15. Star-shaped poly(L-lactide)-b-poly(lactobionamidoethyl methacrylate) with porphyrin core: synthesis, self-assembly, singlet oxygen research and recognition properties.

    PubMed

    Dai, Xiao-Hui; Wang, Zhi-Ming; Pan, Jian-Ming; Yuan, Si-Song; Yan, Yong-sheng; Liu, Dong-Ming; Sun, Lin

    2014-01-01

    Star-shaped porphyrin-cored poly(L-lactide)-b-poly(lactobionamidoethyl methacrylate) block copolymers (SPPLA-b-PLAMA) were synthesized via RAFT of unprotected Lactobionamidoethyl methacrylate (LAMA) in 1-methyl-2-pyrrolidinone (NMP) solution at 70 °C. The structure of this as-synthesized SPPLA-b-PLAMA block copolymer was thoroughly studied by nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), and Fourier transforms infrared. Moreover, under the irradiation, such SPPLA-b-PGAMA copolymer exhibits efficient singlet oxygen generation (0.17) and indicates high fluorescence quantum yields (0.20). Notably, with UV-vis investigation, SPPLA-b-PLAMA showed a very specific recognition with RCA120 lectin. This will not only provide potentially prophyrin-cored star-shaped SPPLA-b-PLAMA block copolymers for targeted photodynamic therapy, but also improve the physical, biodegradation, biocompatibility properties of PLA-based biomaterials. PMID:25138060

  16. Synthesis of Well-Defined Miktoarm Star Copolymer composed of Poly(3-hexylthiophene) and Poly(methyl methacrylate) via combining anionic polymerization and click reaction

    NASA Astrophysics Data System (ADS)

    Park, Jicheol; Moon, Hong Chul; Kim, Jin Kon

    2013-03-01

    We synthesized well-defined miktoarm star copolymer composed of regioregular poly(3-hexylthiophene) and poly(methyl methacrylate) ((P3HT)2- b-PMMA) by combining anionic polymerization and click reaction. First, we synthesized PMMA terminated with 1,3,5-tris(bromomethy)lbenzene (PMMA-(br)2) by anionic polymerization. Then, the bromide end groups transformed to azide group (PMMA-(N3)2) . For the synthesis (P3HT)2- b-PMMA, click reaction between ethynyl-capped P3HT and PMMA-(N3)2 was performed. The optical property and thin film morphology of (P3HT)2- b-PMMA were investigated by using UV-Vis spectra and atomic force microscopy, respectively.

  17. Characterization of poly(diphenylamine)-gold nanocomposites obtained by self-assembly

    NASA Astrophysics Data System (ADS)

    Showkat, Ali Md; Thang Cao, Xuan; Kim, Dong Woo; Rafiqul Islam, Md; Lim, Kwon Taek

    2015-03-01

    Composites of poly (diphenylamine) and gold nanoparticles were chemically prepared from solutions which containing methane sulfonic acid (MSA) with the addition of gold chloride trihydrate as the oxidant as a source for initiation of polymerization and a generation of Au nanoparticles. Poly (diphenylamine) decorated with noble-metal gold nanoparticles were synthesized successfully and exposure of the solutions to caused polymerization of diphenylamine to polymerize with gold salt. The nanocomposites were characterized for the structure, morphology and electronic properties through X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM) and UV-visible spectroscopy.

  18. Synthesis, Characterization, and Size Control of Zinc Sulfide Nanoparticles Capped by Poly(ethylene glycol)

    NASA Astrophysics Data System (ADS)

    Allehyani, S. H. A.; Seoudi, R.; Said, D. A.; Lashin, A. R.; Abouelsayed, A.

    2015-11-01

    Zinc sulfide nanoparticles with controllable size were synthesized by chemical precipitation. Results from transmission electron microscopy and x-ray powder diffraction showed the samples were grown with the cubic phase. Particle size was varied by varying the molar ratio of zinc chloride to sodium sulfide in the presence of poly(ethylene glycol). The optical band gap was calculated on the basis of ultraviolet-visible spectroscopy and ranged from 4.13 to 4.31 eV depending on particle size. Surface passivation and adsorption of poly (ethylene glycol) on the nanoparticles was explained on the basis of Fourier-transform infrared measurements.

  19. Synthesis of poly(1-aminonaphthalene) and poly(1-aminoanthracene) by chemical oxidative polymerization and characterization of the polymers

    SciTech Connect

    Moon, Doo Kyung; Osakada, Kohtaro; Maruyama, Tsukasa; Yamamoto, Takakazu; Kubota, Kenji

    1993-12-06

    Poly(1-aminonaphthalene) and poly(1-aminoanthracene) have been synthesized in high yields (90--96%) by chemical oxidative polymerization of 1-aminonaphthalene and 1-aminoanthracene using H{sub 2}O{sub 2} in the presence of Fe catalyst. The oxidative polymerization of 1-aminonaphthalene and 1-aminoanthracene proceeds via successive coupling that gives the polymer structure similar to polyaniline. The polymers are brown powders and soluble in dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), H{sub 2}SO{sub 4}, and HCOOH. The obtained poly(1-aminonaphthalene) and poly(1-aminoanthracene) show electrical conductivities of 1.7 {times} 10{sup {minus}6} and 1.6 {times} 10{sup {minus}4} S cm{sup {minus}1}, respectively, which increase to 3.8 {times} 10{sup {minus}4}-1.5 {times} 10{sup {minus}3} S cm{sup {minus}1} on doping with HCl or I{sub 2}. Light scattering measurements of the polymers in NMP shows a large degree of depolarization ({rho}{sub v} = 0.33), indicating that the polymers have a linear and stiff structure. The number-average molecular weights (M{sub n}) of poly(1-aminonaphthalene) and poly(1-aminoanthracene) obtained are determined as 4,300 and 4,500, respectively, with narrow molecular weight distribution by gel permeation chromatography (vs polystyrene). The weight-average molecular weight (M{sub b}) of poly(1-aminoanthracene) determined by the light scattering method is 7,000. {sup 1}H NMR spectra of PNA and PAA in DMSO-d{sub 6} give rise to the absorption of the NH hydrogen in the region of {delta} 5--6 ppm, and the NH hydrogen of PNA is exchangeable with the water hydrogen contained in DMSO-d{sub 6} on the NMR time scale with an activation energy of 27 kJ mol{sup {minus}1}. PNA and PAA do not show a distinct absorption peak in the visible region.

  20. Preparation of poly(NIPAAm)-Pluronic F68 as a thermosensitive surfactant for a controlled drug release.

    PubMed

    Choi, Sung-Wook; Lee, Hye Min; Park, Tae-Joon; Kim, Jung-Hyun

    2011-04-01

    This paper describes the synthesis of thermosensitive surfactants by polymerizing N-isopropylacrylamide (NIPAAm) into the Pluronic F68 surfactant and their application for a controlled drug release. Poly(NIPAAm)-Pluronic surfactants with different lengths of the NIPAAm block were synthesized by activating two hydroxyl groups of poly(ethylene oxide) (PEO) at the end of Pluronic F68 using cerium ammonium nitrate (CAN, redox initiator), followed by adding the NIPAAm monomer into a reactor. The resultant poly(NIPAAm)-Pluronic surfactants were characterized by FT-IR and gel filtration chromatography (GPC). It was observed that their critical micellar concentrations increased with an increase in the length of the poly(NIPAAm) block. In addition, poly(D,L-lactide-co-glycolide) (PLGA) microparticles was prepared by an oil-in-water emulsion and solvent evaporation method using the poly(NIPAAm)-Pluronic surfactants in an aqueous continuous phase. At 37°C, nile red (model dye) was released from the PLGA microparticles in a more sustained manner when the length of poly(NIPAAm) was longer due to a thicker layer of shrunken poly(NIPAAm) at the surface of the microparticles. PMID:23071926

  1. Poly(lactide)-block-poly([epsilon]-caprolactone-co-[epsilon]-decalactone)-block-poly(lactide) copolymer elastomers

    SciTech Connect

    Schneiderman, Deborah K.; Hill, Erin M.; Martello, Mark T.; Hillmyer, Marc A.

    2015-08-28

    Batch ring opening transesterification copolymerization of ε-caprolactone and ε-decalactone was used to generate statistical copolymers over a wide range of compositions and molar masses. Reactivity ratios determined for this monomer pair, rCL = 5.9 and rDL = 0.03, reveal ε-caprolactone is added preferentially regardless of the propagating chain end. Relative to poly(ε-caprolactone) the crystallinity and melting point of these statistical copolymers were depressed by the addition of ε-decalactone; copolymers containing greater than 31 mol% (46 wt%) ε-decalactone were amorphous. Poly(lactide)-block-poly(ε-caprolactone-co-ε-decalactone)-block-poly(lactide) triblock polymers were also prepared and used to explore the influence of midblock composition on the temperature dependent Flory-Huggins interaction parameter (χ). In addition, uniaxial extension tests were used to determine the effects of midblock composition, poly(lactide) content, and molar mass on the mechanical properties of these new elastomeric triblocks.

  2. Confined Flocculation of Ionic Pollutants by Poly(L-dopa)-Based Polyelectrolyte Complexes in Hydrogel Beads for Three-Dimensional, Quantitative, Efficient Water Decontamination.

    PubMed

    Yu, Li; Liu, Xiaokong; Yuan, Weichang; Brown, Lauren Joan; Wang, Dayang

    2015-06-16

    The development of simple and recyclable adsorbents with high adsorption capacity is a technical imperative for water treatment. In this work, we have successfully developed new adsorbents for the removal of ionic pollutants from water via encapsulation of polyelectrolyte complexes (PECs) made from positively charged poly(allylamine hydrochloride) (PAH) and negatively charged poly(l-3,4-dihydroxyphenylalanine) (PDopa), obtained via the self-polymerization of l-3,4-dihydroxyphenylalanine (l-Dopa). Given the outstanding mass transport through the hydrogel host matrixes, the PDopa-PAH PEC guests loaded inside can effectively and efficiently remove various ionic pollutants, including heavy metal ions and ionic organic dyes, from water. The adsorption efficiency of the PDopa-PAH PECs can be quantitatively correlated to and tailored by the PDopa-to-PAH molar ratio. Because PDopa embodies one catechol group, one carboxyl group, and one amino group in each repeating unit, the resulting PDopa-PAH PECs exhibit the largest capacity of adsorption of heavy metal ions compared to available adsorbents. Because both PDopa and PAH are pH-sensitive, the PDopa-PAH PEC-loaded agarose hydrogel beads can be easily and completely recovered after the adsorption of ionic pollutants by adjusting the pH of the surrounding media. The present strategy is similar to the conventional process of using PECs to flocculate ionic pollutants from water, while in our system flocculation is confined to the agarose hydrogel beads, thus allowing easy separation of the resulting adsorbents from water. PMID:25981870

  3. Active targeting co-delivery system based on pH-sensitive methoxy-poly(ethylene glycol)2K-poly(ε-caprolactone)4K-poly(glutamic acid)1K for enhanced cancer therapy.

    PubMed

    Li, Nuannuan; Huang, Chunzhi; Luan, Yuxia; Song, Aixin; Song, Yunmei; Garg, Sanjay

    2016-06-15

    In this paper, we successfully synthesized folate-modified pH-sensitive copolymer methoxy-poly(ethylene glycol)2K-poly(ε-caprolactone)4K-poly(glutamic acid)1K (mPEG2K-PCL4K-PGA1K-FA), which could form the polymeric assembly in an aqueous solution, for co-delivering hydrophilic drugs doxorubicin hydrochloride (DOX) and verapamil hydrochloride (VER) (FA-poly(DOX+VER)). Since VER was an effective P-glycoprotein inhibitor, the combination of DOX and VER could reverse the multidrug resistance efficiently and enhance the therapeutic effect. Therefore, the inhibition ratios of MCF-7/ADR resistant cancer cell treated by FA-poly (DOX+VER) were almost more than 30% higher than those of FA-polyDOX after 48h and 72h. Furthermore, the conjugation of FA could lead the co-delivery systems actively targeting into the FA receptor over-expressing cancer cells in addition to the passive accumulation of the assembly in tumor tissues. Importantly, the prepared mPEG2K-PCL4K-PGA1K-FA assembly showed high pH-sensitive property, which made the drugs mostly released in tumor tissue (acid environment) than in physiological environment (neutral environment). In summary, the as-prepared co-delivery system FA-poly(DOX+VER) demonstrated a high efficiency in reversing the multidrug resistance and targeting FA receptor to improve the anticancer effect of DOX in MCF-7/ADR resistant cells. PMID:27016914

  4. Mesoporous CeO2 nanoparticles synthesized by an inverse miniemulsion technique and their catalytic properties in methane oxidation

    NASA Astrophysics Data System (ADS)

    Nabih, Nermeen; Schiller, Renate; Lieberwirth, Ingo; Kockrick, Emanuel; Frind, Robert; Kaskel, Stefan; Weiss, Clemens K.; Landfester, Katharina

    2011-04-01

    Cerium(IV) oxide nanoparticles were synthesized using an inverse miniemulsion technique with cerium nitrate hexahydrate as precursor. The resulting nanocrystallites are as small as 5 nm with a specific surface area of 158 m2 g - 1 after calcination at 400 °C. With the addition of cetyltrimethylammonium bromide (CTAB) or (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)) triblock copolymers (PEO-PPO-PEO) as template in the miniemulsion droplets, the specific surface area can be increased up to 255 m2 g - 1. The miniemulsions were characterized by dynamic light scattering (DLS) and the obtained oxides were examined by x-ray diffraction (XRD), nitrogen sorption (BET and BJH), and transmission electron microscopy (TEM). The catalytic activity of the resulting ceria was investigated for the temperature-programmed oxidation (TPO) of methane.

  5. Biodegradable Poly(aminoester)-Mediated p53 Gene Delivery for Cancer Therapy.

    PubMed

    Shen, He; Liu, Min; Zhang, Zhijun

    2016-03-01

    Gene therapy is a promising strategy in cancer treatment. However, efficient gene translation still remains challenging. In the previous work, a hydrolytically degradable poly(aminoester) with good biocompatibility was synthesized. Herein, the poly(aminoester) was explored as a vector for gene delivery and cancer therapy. The experiments revealed that the poly(aminoester) condensed plasmid DNA into nanosized particles via electrostatic interaction. The pEGFP-N1 and pGL-3 were first used as two reporter genes to study intracellular transfection. The poly(aminoester) showed higher GFP expression (33%) than PEI 25 kDa (21%). Intracellular trafficking of Cy3-labelled pGL-3 also indicated that the poly(aminoester) showed superior DNA delivery ability to nucleus compared to PEI 25 kDa. Furthermore, the therapeutic gene (p53) was translated into the breast cancer cell line (MCF-7), and then induced cell apoptosis. These results suggested that the degradable poly(aminoester) is a promising and efficient gene delivery vector for gene therapeutic applications. PMID:27455620

  6. Regulation of chromatin structure by poly(ADP-ribosyl)ation

    PubMed Central

    Beneke, Sascha

    2012-01-01

    The interaction of DNA with proteins in the context of chromatin has to be tightly regulated to achieve so different tasks as packaging, transcription, replication and repair. The very rapid and transient post-translational modification of proteins by poly(ADP-ribose) has been shown to take part in all four. Originally identified as immediate cellular answer to a variety of genotoxic stresses, already early data indicated the ability of this highly charged nucleic acid-like polymer to modulate nucleosome structure, the basic unit of chromatin. At the same time the enzyme responsible for synthesizing poly(ADP-ribose), the zinc-finger protein poly(ADP-ribose) polymerase-1 (PARP1), was shown to control transcription initiation as basic factor TFIIC within the RNA-polymerase II machinery. Later research focused more on PARP-mediated regulation of DNA repair and cell death, but in the last few years, transcription as well as chromatin modulation has re-appeared on the scene. This review will discuss the impact of PARP1 on transcription and transcription factors, its implication in chromatin remodeling for DNA repair and probably also replication, and its role in controlling epigenetic events such as DNA methylation and the functionality of the insulator protein CCCTC-binding factor. PMID:22969794

  7. Experimental and theoretical studies on inhibition of mild steel corrosion by some synthesized polyurethane tri-block co-polymers

    PubMed Central

    Kumar, Sudershan; Vashisht, Hemlata; Olasunkanmi, Lukman O.; Bahadur, Indra; Verma, Hemant; Singh, Gurmeet; Obot, Ime B.; Ebenso, Eno E.

    2016-01-01

    Polyurethane based tri-block copolymers namely poly(N-vinylpyrrolidone)-b-polyurethane-b-poly(N-vinylpyrrolidone) (PNVP-PU) and poly(dimethylaminoethylmethacrylate)-b-polyurethane-b-poly(dimethylaminoethylmethacrylate) (PDMAEMA-PU) were synthesized through atom transfer radical polymerization (ATRP) mechanism. The synthesized polymers were characterized using nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC) methods. The corrosion inhibition performances of the compounds were investigated on mild steel (MS) in 0.5 M H2SO4 medium using electrochemical measurements, surface analysis, quantum chemical calculations and molecular dynamic simulations (MDS). Potentiodynamic polarization (PDP) measurements revealed that the polymers are mixed-type corrosion inhibitors. Electrochemical impedance spectroscopy (EIS) measurements showed that the polymers inhibit MS corrosion by adsorbing on MS surface to form pseudo-capacitive interface. The inhibitive effects of the polymers increase with increasing concentration and decrease with increasing temperature. The adsorption of both the polymers on MS surface obey the Langmuir adsorption isotherm and involves both physisorption and chemisorption mechanisms. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses showed that the polymers formed protective film on MS surface and shield it from direct acid attack. Quantum chemical calculations and molecular dynamic simulations studies corroborate experimental results. PMID:27515383

  8. Experimental and theoretical studies on inhibition of mild steel corrosion by some synthesized polyurethane tri-block co-polymers.

    PubMed

    Kumar, Sudershan; Vashisht, Hemlata; Olasunkanmi, Lukman O; Bahadur, Indra; Verma, Hemant; Singh, Gurmeet; Obot, Ime B; Ebenso, Eno E

    2016-01-01

    Polyurethane based tri-block copolymers namely poly(N-vinylpyrrolidone)-b-polyurethane-b-poly(N-vinylpyrrolidone) (PNVP-PU) and poly(dimethylaminoethylmethacrylate)-b-polyurethane-b-poly(dimethylaminoethylmethacrylate) (PDMAEMA-PU) were synthesized through atom transfer radical polymerization (ATRP) mechanism. The synthesized polymers were characterized using nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC) methods. The corrosion inhibition performances of the compounds were investigated on mild steel (MS) in 0.5 M H2SO4 medium using electrochemical measurements, surface analysis, quantum chemical calculations and molecular dynamic simulations (MDS). Potentiodynamic polarization (PDP) measurements revealed that the polymers are mixed-type corrosion inhibitors. Electrochemical impedance spectroscopy (EIS) measurements showed that the polymers inhibit MS corrosion by adsorbing on MS surface to form pseudo-capacitive interface. The inhibitive effects of the polymers increase with increasing concentration and decrease with increasing temperature. The adsorption of both the polymers on MS surface obey the Langmuir adsorption isotherm and involves both physisorption and chemisorption mechanisms. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses showed that the polymers formed protective film on MS surface and shield it from direct acid attack. Quantum chemical calculations and molecular dynamic simulations studies corroborate experimental results. PMID:27515383

  9. Nanocalcium-deficient hydroxyapatite-poly (e-caprolactone)-polyethylene glycol-poly (e-caprolactone) composite scaffolds.

    PubMed

    Wang, Zhiwei; Li, Ming; Yu, Baoqing; Cao, Liehu; Yang, Qingsong; Su, Jiacan

    2012-01-01

    A bioactive composite of nano calcium-deficient apatite (n-CDAP) with an atom molar ratio of calcium to phosphate (Ca/P) of 1.50 and poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ-caprolactone) (PCL-PEG-PCL) was synthesized, and a composite scaffold was fabricated. The composite scaffolds with 40 wt% n-CDAP contained well interconnected macropores around 400 μm, and exhibited a porosity of 75%. The weight-loss ratio of the n-CDAP/PCL-PEG-PCL was significantly greater than nano hydroxyapatite (n-HA, Ca/P = 1.67)/PCL-PEG-PCL composite scaffolds during soaking into phosphate-buffered saline (pH 7.4) for 70 days, indicating that n-CDAP-based composite had good degradability compared with n-HA. The viability ratio of MG-63 cells was significantly higher on n-CDAP than n-HA-based composite scaffolds at 3 and 5 days. In addition, the alkaline phosphatase activity of the MG-63 cells cultured on n-CDAP was higher than n-HA-based composite scaffolds at 7 days. Histological evaluation showed that the introduction of n-CDAP into PCL-PEG-PCL enhanced the efficiency of new bone formation when the composite scaffolds were implanted into rabbit bone defects. The results suggested that the n-CDAP-based composite exhibits good biocompatibility, biodegradation, and osteogenesis in vivo. PMID:22848159

  10. Characterization, biodegradability and blood compatibility of poly[(R)-3-hydroxybutyrate] based poly(ester-urethane)s.

    PubMed

    Liu, Qiaoyan; Cheng, Shaoting; Li, Zibiao; Xu, Kaitian; Chen, Guo-Qiang

    2009-09-15

    Poly(ester-urethane)s (PUs) were synthesized using hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) to join short chains (M(n) = 2000) of poly(R-3-hydroxybutyrate) (PHB) diols and poly(epsilon-caprolactone) (PCL) diols with different feed ratios under different reaction conditions. The multiblock copolymers were characterized by nuclear magnetic resonance spectrometer (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). XRD spectra and second DSC heat thermograms of the multiblock copolymers revealed that the crystallization of both PHB and PCL segments was mutually restricted, and, especially, the PCL segment limited the cold crystallization of the PHB segment. The SEM of platelet adhesion experiments showed that the hemocompatibility was affected to some extent by the chain flexibility of the polymers. Hydrolysis studies demonstrated that the hydrolytic degradation of PUs was generated from the scission of their ester bonds or/and urethane bonds. Simultaneously, the rate of ester bond scission was determined to some extent by the crystallization degree, which was further affected by the configuration of polymer chains. These highly elastic multiblock copolymers combining hemocompatibility and biodegradability may be developed into blood contact implant materials for biomedical applications. PMID:18671259

  11. Biodegradable radiopaque iodinated poly(ester urethane)s containing poly(ε-caprolactone) blocks: synthesis, characterization, and biocompatibility.

    PubMed

    Sang, Lin; Wei, Zhiyong; Liu, Keliang; Wang, Xinhui; Song, Kedong; Wang, Hong; Qi, Min

    2014-04-01

    Biodegradable radiopaque iodinated poly(ester-urethane) (I-PU), consisting of poly(ε-caprolactone) (PCL) diol and iodinated bisphenol A (IBPA), has been successfully synthesized via a coupling reaction of PCL-diisocyanate and IBPA with varying compositions. The IBPA with four iodine atoms per molecule was applied as a chain extender to endow the I-PUs with intrinsic X-ray visibility. The chemical structure and molecular weights of I-PUs were characterized by Fourier transform infrared spectroscopy (FT-IR), proton-nuclear magnetic resonance, and gel permeation chromatography (GPC). The effects of IBPA on the physical properties of I-PUs were systematically studied by means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and wide-angle X-ray diffraction (WAXD). The DSC results showed that the crystallization of PCL segments in I-PUs was restrained with increasing amount of IBPA, which was also confirmed by WAXD. In the X-radiography analysis, all the synthesized I-PUs exhibited high radiopacity compared with an aluminum wedge of equivalent thickness. Enzymatic degradation tests showed that the incorporation of IBPA prolonged the degradation of I-PUs and distinct mass loss and degradation happened in the third month. Basic cytocompatibility conducted using rat adipose-derived cells proved that all the I-PUs and their biodegradation products were nontoxic. The radiopaque I-PUs is expected to possess a significant advantage over the traditional polymer counterparts in some related biomedical fields. PMID:23640806

  12. Massachusetts Special Olympics Poly Hockey.

    ERIC Educational Resources Information Center

    Morrissey, Jim

    Poly Hockey is featured in this manual of instructions for coaches and teachers to use with mentally retarded boys and girls of all ages and ability levels. It is noted that the sport has been supported by the Board of Directors of the Special Olympics and has been used in Massachusetts for over 7 years. Explained is use of the game indoors, and…

  13. Leadership, Rhetoric, and the "Polis."

    ERIC Educational Resources Information Center

    Gellis, Mark

    2002-01-01

    Discusses some of the relationships between rhetoric and the concepts of leadership and the "polis" (the active assembly of citizens empowered to discuss and make public policy). Argues that the study of leadership belongs in composition, rhetoric, and communication and that scholars and teachers are more than justified in studying leadership and…

  14. Freestanding doped silicon nanocrystals synthesized by plasma

    NASA Astrophysics Data System (ADS)

    Ni, Zhenyi; Pi, Xiaodong; Ali, Muhammad; Zhou, Shu; Nozaki, Tomohiro; Yang, Deren

    2015-08-01

    Freestanding silicon nanocrystals (Si NCs) have recently gained great popularity largely due to their easily accessible surface and flexible incorporation into device structures. In the past decade plasmas have been increasingly employed to synthesize freestanding Si NCs. As freestanding Si NCs move closer to applications in a variety of fields such as electronics, thermoelectrics and lithium-ion batteries, doping becomes more imperative. Such a context explains the current great interest in plasma-synthesized doped freestanding Si NCs. In this work we review the synthesis of freestanding doped Si NCs by plasma. Doping-induced structural, electronic, optical and oxidation properties of Si NCs are discussed. We also review the applications of plasma-synthesized doped freestanding Si NCs that have been demonstrated so far. The development of freestanding doped Si NCs synthesized by plasma in the future is envisioned.

  15. ORGANIC SYNTHESES USING MICROWAVES AND SUPPORTED REAGENTS

    EPA Science Inventory

    Microwave-accelerated chemical syntheses under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although the use of dedicated MW equipment...

  16. 21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... polymerization of p-methylstyrene. (2) Rubber-modified poly(p-methylstyrene) (CAS Reg. No. 33520-88-6) polymer... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Poly(p-methylstyrene) and rubber-modified poly(p... Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). Poly(p-methylstyrene) and...

  17. Expanding the light absorption of poly(3-hexylthiophene) by end-functionalization with π-extended porphyrins.

    PubMed

    Chevrier, Michèle; Richeter, Sébastien; Coulembier, Olivier; Surin, Mathieu; Mehdi, Ahmad; Lazzaroni, Roberto; Evans, Rachel C; Dubois, Philippe; Clément, Sébastien

    2016-01-01

    Poly(3-hexylthiophene)s end-functionalized with π-extended porphyrins have been synthesized in a one-pot procedure. The polymers show a broad absorption profile extending to 700 nm and a fibrillar microstructure, which can be tuned through judicious selection of the porphyrin molar ratio. PMID:26506849

  18. A novel biobased plasticizer of epoxidized cardanol glycidylether: Synthesis and application in soft poly(vinyl chloride) films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel plasticizer derived from cardanol, epoxied cardanol glycidyl ether (ECGE), was synthesized and characterized by 1H-NMR and 13C-NMR. Effects of the ECGE combined with dioctyl phthalate (DOP), a commercial plasticizer, in soft poly(vinyl chloride) (PVC) films were studied. Dynamic mechanical a...

  19. Stereoregularity of poly (lactic acid) and their model compounds as studied by NMR and quantum chemical calculations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to understand the origin of the tacticity splitting in the NMR spectrum of poly(lactic acid), monomer model compound and dimer model compounds (both isotactic and syndiotactic) were synthesized and their 1H and 13C NMR chemical shifts observed. Two energetically stable conformations were o...

  20. MICROWAVE-ASSISTED SHAPE CONTROLLED BULK SYNTHESIS OF AG AND FE NANORODS IN POLY (ETHYLENE GLYCOL) SOLUTIONS

    EPA Science Inventory

    Bulk syntheses of silver (Ag) and iron (Fe) nanorods using poly (ethylene glycol), PEG, under microwave irradiation (MW) conditions are reported. Favorable conditions to make Ag nanorods were established and can be extended to make Fe nanorods with uniform size and shape. The nan...

  1. Collagen-poly(dialdehyde) guar gum based porous 3D scaffolds immobilized with growth factor for tissue engineering applications.

    PubMed

    Ragothaman, Murali; Palanisamy, Thanikaivelan; Kalirajan, Cheirmadurai

    2014-12-19

    Here we report the preparation of collagen-poly(dialdehyde) guar gum based hybrid functionalized scaffolds covalently immobilized with platelet derived growth factor - BB for tissue engineering applications. Poly(dialdehyde) guar gum was synthesized from selective oxidation of guar gum using sodium periodate. The synthesized poly(dialdehyde) guar gum not only promotes crosslinking of collagen but also immobilizes the platelet derived growth factor through imine bonds. The covalent crosslinking formed in collagen improves thermal, swelling and biodegradation properties of the hybrid scaffolds. The prepared hybrid scaffolds show 3D interconnected honeycomb porous structure when viewed under a microscope. The release of immobilized platelet derived growth factor was seen up to 13th day of incubation thereby proving its sustained delivery. The developed hybrid scaffold leads to a quantum increase in NIH 3T3 fibroblast cell density and proliferation thereby demonstrating its potential for tissue engineering applications. PMID:25263907

  2. Facile Synthesis and Characterization of Well-Defined Rod-Coil Block Copolymers Composed of Regioregular Poly(3-hexyl thiophene)

    NASA Astrophysics Data System (ADS)

    Moon, Hong Chul; Kim, Jin Kon

    2011-03-01

    We synthesized rod-coil block copolymers composed of regioregular poly(3-hexyl thiopene) (P3HT) block via anionic coupling reaction. Three different coil blocks (poly(2-vinyl pyridine) (P2VP) and polyisoprene (PI)) and poly(methyl methacrylate) (PMMA)) were selected. For the synthesis of P2VP- b -P3HT- b -P2VP and P2VP- b -P3HT- b -P2VP, the chain ends of the P3HT were capped by the aldehyde group. On the other hand, phenyl acrylate (PA)-capped P3HT was prepared for coupling reaction with living PMMA anions. When the excess amount of the used living anions was removed by column chromatography, all of the neat block copolymers showed lower PDI without leaving any homopolymers. We also investigated the optical property and thin film morphology of synthesized various block copolymers.

  3. The effect of hard/soft segment composition on radiation stability of poly(ester-urethane)s

    NASA Astrophysics Data System (ADS)

    Walo, Marta; Przybytniak, Grażyna; Łyczko, Krzysztof; Piątek-Hnat, Marta

    2014-01-01

    In this paper studies on the structures and radiation stability of four poly(ester-urethane)s (PUR)s synthesized from oligo(ethylene-butylene adipate)diol of various molecular weights and isophorone diisocyanate/1,4-butanediol are reported. PURs with 40 and 60 wt% soft segments were irradiated at ambient temperature with a high energy electron beam to a dose of 112 kGy. The effect of different segmental compositions on thermal and mechanical properties of polyurethanes, both before and after irradiation, were investigated using mechanical testing and dynamic mechanical thermal analysis. ATR-FTIR spectroscopy was used to study the progress of polycondensation, structure of synthesized polymers and extent of phase separation were determined on a basis of the contribution of hydrogen bonding in poly(ester-urethane)s. Correlation between degree of phase separation and mechanical and thermal properties of poly(ester-urethane)s was found.

  4. Psychoacoustic Analysis of Synthesized Jet Noise

    NASA Technical Reports Server (NTRS)

    Okcu, Selen; Rathsam, Jonathan; Rizzi, Stephen A.

    2013-01-01

    An aircraft noise synthesis capability is being developed so the annoyance caused by proposed aircraft can be assessed during the design stage. To make synthesized signals as realistic as possible, high fidelity simulation is required for source (e.g., engine noise, airframe noise), propagation and receiver effects. This psychoacoustic study tests whether the jet noise component of synthesized aircraft engine noise can be made more realistic using a low frequency oscillator (LFO) technique to simulate fluctuations in level observed in recordings. Jet noise predictions are commonly made in the frequency domain based on models of time-averaged empirical data. The synthesis process involves conversion of the frequency domain prediction into an audible pressure time history. However, because the predictions are time-invariant, the synthesized sound lacks fluctuations observed in recordings. Such fluctuations are hypothesized to be perceptually important. To introduce time-varying characteristics into jet noise synthesis, a method has been developed that modulates measured or predicted 1/3-octave band levels with a (<20Hz) LFO. The LFO characteristics are determined through analysis of laboratory jet noise recordings. For the aft emission angle, results indicate that signals synthesized using a generic LFO are perceived as more similar to recordings than those using no LFO, and signals synthesized with an angle-specific LFO are more similar to recordings than those synthesized with a generic LFO.

  5. Bioengineering Functional Copolymers. IX. Poly[(maleic anhydride-co-hexene-1)-g-poly(ethylene oxide)].

    PubMed

    Mazi, Hidayet; Kibarer, Günay; Emregül, Emel; Rzaev, Zakir M O

    2006-04-12

    Amphiphilic bioengineering copolymers having a combination of hydrophilic/hydrophobic linkages and polyelectrolyte behavior, along with an ability to interact with biomacromolecules, in particular with the invertase enzyme, have been synthesized by (a) complex-radical copolymerization of maleic anhydride (MA, the acceptor) and hexene-1 (H-1, the donor) monomers with benzoyl peroxide as the initiator in 1,4-dioxane at 65 degrees C under high-conversion conditions and (b) subsequent grafting (polyesterification) of synthesized poly(MA-alt-H-1) with alpha-methoxy-omega-hydroxy-poly(ethylene oxide) (PEO). Copolymerizations were also carried out in the steady state, in order to essentially reduce the effect of copolymer composition drift. The values of the monomer reactivity ratios (r(1) and r(2)) determined by using the known terminal models of Fineman-Ross (FR) and Kelen-Tüdös (KT), as well as by nonlinear regression (NLR) analysis, are: r(1) = 0.16 and r(2) = 0.30 (FR), r(1) = 0.14 and r(2) = 0.27 (KT), and r(1) = 0.15 and r(2) = 0.29 (NLR), respectively. All the copolymers and graft copolymers were characterized by FTIR spectroscopy, (1)H{(13)C} NMR spectroscopy, viscometric measurements, and chemical (acid number), thermal (DSC and TGA), and X-ray diffraction analyses. Unlike poly(MA-alt-H-1)s, PEO macrobranched graft copolymers exhibit expressed polyelectrolyte and swelling behavior in diluted and concentrated dioxane solutions, respectively. The copolymer and its PEO hyperbranched derivatives can be used as carriers for enzyme immobilization. PMID:16572476

  6. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    SciTech Connect

    Mahmud, Maznah; Daik, Rusli; Adam, Zainah

    2015-09-25

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels’ network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

  7. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    NASA Astrophysics Data System (ADS)

    Mahmud, Maznah; Daik, Rusli; Adam, Zainah

    2015-09-01

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels' network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

  8. Control of the plasmon resonance from poly-dispersed silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Hyun, Jae Young; Yun, Changhun; Kim, Ki Hyun; Kim, Wan Ho; Jeon, Sie-Wook; Im, Won Bin; Kim, Jae Pil

    2015-02-01

    Poly-dispersed silver nanoparticles (AgNPs) were synthesized through a polyol reaction and separated by a centrifuging process to control the target plasmon resonance frequency. When the ratio between the polar side group of polyvinyl pyrrolidone and silver ions is less than 1, AgNPs of various sizes and a broad extinction spectrum can be obtained through a single process. Following the physical separation of the poly-dispersed AgNPs, both the plasmon resonance and the size distribution can be tuned depending on the centrifuging speed. Fitting the measured absorption spectrum using a Mie calculation confirms that the centrifuging method of poly-dispersed AgNPs is compatible with a simple and reliable form of fabrication for selectively extraction AgNPs with a desired size distribution.

  9. Poly(esterimide) bearing azobenzene units as photoaligning layer for liquid crystals

    NASA Astrophysics Data System (ADS)

    Węgłowski, Rafał; Piecek, Wiktor; Kozanecka-Szmigiel, Anna; Konieczkowska, Jolanta; Schab-Balcerzak, Ewa

    2015-11-01

    The custom synthesized azobenzene side-chain poly(esterimide) was used as an aligning material for nematic liquid crystal molecules. The anisotropy of the poly(esterimide) layer was generated by a linearly polarized UV light, as a consequence of multiple trans-cis-trans isomerization cycles. The photoalignment effect was studied by assembling a twisted nematic cell with a proper liquid crystal mixture and geometry to fulfill Mauguin's limit. The polarizing microscope pictures of the fabricated cells confirmed the twisted arrangement of liquid crystal molecules. The results of electro-optic measurements indicated a stronger anchoring of the liquid crystal molecules by photoaligned poly(esterimide) than that obtained in the case of a rubbed polyimide.

  10. Surface decorated poly(ester-ether-urethane)s nanoparticles: a versatile approach towards clinical translation.

    PubMed

    Piras, Anna Maria; Sandreschi, Stefania; Malliappan, Sivakumar Ponnurengam; Dash, Mamoni; Bartoli, Cristina; Dinucci, Dinuccio; Guarna, Francesco; Ammannati, Enrico; Masa, Marc; Múčková, Marta; Schmidtová, Ludmila; Chiellini, Emo; Chiellini, Federica

    2014-11-20

    Poly(ester-ether-urethane)s copolymers are a resourceful class of biopolymers for the preparation of nanocarriers for drug delivery applications. However, a simple clinical translation for this synthetic material with biological and quality features is still needed. In this view, poly(ε-caprolactone)-co-poly(ethylene glycol) copolymers were synthesized as semi-bulk pilot (Kg) scale under mild conditions in absence of catalyst, bearing functional termini such as fluorescein tag and anticancer targeting moieties. The obtained materials were processed into surface decorated paclitaxel (PTX) loaded nanoparticles (NPs). The NPs were fully characterized in vitro and in vivo biodistribution in healthy mice evidenced no sign of toxicity and lower levels of PTX in lung and spleen, compared to clinically applied PTX dosage form. PMID:25178828

  11. Stereo matching image processing by synthesized color and the characteristic area by the synthesized color

    NASA Astrophysics Data System (ADS)

    Akiyama, Akira; Mutoh, Eiichiro; Kumagai, Hideo

    2014-09-01

    We have developed the stereo matching image processing by synthesized color and the corresponding area by the synthesized color for ranging the object and image recognition. The typical images from a pair of the stereo imagers may have some image disagreement each other due to the size change, missed place, appearance change and deformation of characteristic area. We constructed the synthesized color and corresponding color area with the same synthesized color to make the distinct stereo matching. We constructed the synthesized color and corresponding color area with the same synthesized color by the 3 steps. The first step is making binary edge image by differentiating the focused image from each imager and verifying that differentiated image has normal density of frequency distribution to find the threshold level of binary procedure. We used Daubechies wavelet transformation for the procedures of differentiating in this study. The second step is deriving the synthesized color by averaging color brightness between binary edge points with respect to horizontal direction and vertical direction alternatively. The averaging color procedure was done many times until the fluctuation of averaged color become negligible with respect to 256 levels in brightness. The third step is extracting area with same synthesized color by collecting the pixel of same synthesized color and grouping these pixel points by 4 directional connectivity relations. The matching areas for the stereo matching are determined by using synthesized color areas. The matching point is the center of gravity of each synthesized color area. The parallax between a pair of images is derived by the center of gravity of synthesized color area easily. The experiment of this stereo matching was done for the object of the soccer ball toy. From this experiment we showed that stereo matching by the synthesized color technique are simple and effective.

  12. Synthesize of barium ferrite nanowire array by self-fabricated porous silicon template

    NASA Astrophysics Data System (ADS)

    Zheng, Hui; Han, Mangui; Deng, Jiangxia; Zheng, Liang; Wu, Jun; Deng, Longjiang; Qin, Huibin

    2014-08-01

    In this work, we synthesize barium ferrite (BaFe12O19) nanowire array in porous silicon template. The porous silicon templates are prepared via gold-assisted chemical etching method. The gold (Au) nanoparticles with mean diameter of 30 nm and distance of 100 nm were ordered on the surface of Si substrate through the Polystyrene (510000)-block-poly (2-vinylpyridine) (31000) (PS510000-b-P2VP31000) diblock copolymer. Porous silicon templates with mean diameter of 500 nm and distance between the pores of 500 nm were fabricated by two etching steps. BaFe12O19 nanowires with mean diameter of 200 nm were synthesized into a porous silicon template by a sol-gel method. Magnetic hysteresis loops show an isotropic feature of the BaFe12O19 nanowires array. The coercivity (Hc) and squareness ratio (Mr/Ms) of nanowire arrays are 2560 Oe and 0.6, respectively.

  13. Menthols as Chiral Auxiliaries for Asymmetric Cycloadditive Oligomerization: Syntheses and Studies of β-Proline Hexamers.

    PubMed

    Kudryavtsev, Konstantin V; Ivantcova, Polina M; Muhle-Goll, Claudia; Churakov, Andrei V; Sokolov, Mikhail N; Dyuba, Artem V; Arutyunyan, Alexander M; Howard, Judith A K; Yu, Chia-Chun; Guh, Jih-Hwa; Zefirov, Nikolay S; Bräse, Stefan

    2015-12-18

    To produce a novel class of structurally ordered poly-β-prolines, an emergent method for synthesizing chiral β-peptide molecular frameworks was developed based on 1,3-dipolar cycloaddition chemistry of azomethine ylides. Functionalized short β-peptides with up to six monomeric residues were efficiently synthesized in homochiral forms using a cycloadditive oligomerization approach. X-ray, NMR, and CD structural analyses of the novel β-peptides revealed secondary structure features that were generated primarily by Z/E-β-peptide bond isomerism. Anticancer in cellulo activity of the new β-peptides toward hormone-refractory prostate cancer cells was observed and was dependent on the absolute configuration of the stereogenic centers and the chain length of the β-proline oligomers. PMID:26624275

  14. Anti-nociceptive effect of synthesized di-hydroxy flavones: possible mechanism.

    PubMed

    Girija, K; Reddy, M Kannappa; Viswanathan, S

    2002-11-01

    Renewed interest on the research on the flavonoids is gaining more importance. Earlier literature on flavonoids indicated a significant anti-nociceptive action for flavones and mono-substituted flavones. However, they exhibited a ceiling effect. The present study was undertaken by new synthesizing six disubstituted flavones (DHFs) since poly substituted ones are expected to produce more potent effect. Their anti-nociceptive effect and the role of opioid involvement were studied using acetic acid induced abdominal constriction assay. All the six DHFs administered in elicited a dose related inhibition of abdominal constrictions indicating the presence of the anti-nociceptive response. However, these substances also showed a similar ceiling effect. Like other flavonoid substances, they also utilized opioid pathways. It is suggested that these newly synthesized DHFs can be included along with other flavonoids while attempting clinical trial for analgesic use. PMID:13677638

  15. Poly(ethylene glycol) grafted chitosan as new copolymer material for oral delivery of insulin

    NASA Astrophysics Data System (ADS)

    Ho, Thanh Ha; Thanh Le, Thi Nu; Nguyen, Tuan Anh; Chien Dang, Mau

    2015-09-01

    A new scheme of grafting poly (ethylene glycol) onto chitosan was proposed in this study to give new material for delivery of insulin over oral pathway. First, methoxy poly(ethylene glycol) amine (mPEGa MW 2000) were grafted onto chitosan (CS) through multiples steps to synthesize the grafting copolymer PEG-g-CS. After each synthesis step, chitosan and its derivatives were characterized by FTIR, 1H NMR Then, insulin loaded PEG-g-CS nanoparticles were prepared by cross-linking of CS with sodium tripolyphosphate (TPP). Same insulin loaded nanoparticles using unmodified chitosan were also prepared in order to compare with the modified ones. Results showed better protecting capacity of the synthesized copolymer over original CS. CS nanoparticles (10 nm of size) were gel like and high sensible to temperature as well as acidic environment while PEG-g-CS nanoparticles (200 nm of size) were rigid and more thermo and pH stable.

  16. Chemosynthesis of poly(ε-lysine)-analogous polymers by microwave-assisted click polymerization.

    PubMed

    Guo, Jinshan; Wei, Ying; Zhou, Dongfang; Cai, Pingqiang; Jing, Xiabin; Chen, Xue-Si; Huang, Yubin

    2011-03-14

    Poly(ε-lysine) (ε-PL)-analogous click polypeptides with not only similar α-amino side groups but also similar main chain to ε-PL were chemically synthesized for the first time through click polymerization from aspartic (or glutamic)-acid-based dialkyne and diazide monomers. With microwave-assisting, the reaction time of click polymerization was compressed into 30 min. The polymers were fully characterized by NMR, ATR-FTIR, and SEC-MALLS analysis. The deprotected click polypeptides had similar pK(a) value (7.5) and relatively low cytotoxicity as ε-PL and could be used as substitutes of ε-PL in biomedical applications, especially in endotoxin selective removal. Poly(ethylene glycol) (PEG)-containing alternating copolymers with α-amino groups were also synthesized and characterized. After deprotection, the polymers could be used as functional gene vector with PEG shadowing system and NCA initiator to get amphiphilic graft polymers. PMID:21302898

  17. Synthesis of functionalized poly(ester carbonate) with laminin-derived peptide for promoting neurite outgrowth of PC12 cells.

    PubMed

    Xing, Dongming; Ma, Lie; Gao, Changyou

    2014-10-01

    Maleimide-functionalized poly(ester carbonate)s are synthesized by ring-opening copolymerization of furan-maleimide functionalized trimethylene carbonate (FMTMC) with L-lactide and a subsequent retro Diels-Alder reaction. The maleimide groups on poly(ester carbonate)s are amenable to Michael addition with thiol-containing molecules such as 3-mercapto-1-propanol, 2-aminoethanethiol hydrochloride, and mercaptoacetic acid under mild conditions, enabling the formation of biodegradable materials with various functional groups (e.g., hydroxyl, amine, and carboxyl). In particular, the maleimide-functionalized poly(ester carbonate) is clicked with a laminin-derived peptide CQAASIKVAV. In vitro culture of PC12 cells shows that the maleimide-functionalized polymers, especially the CQAASIKVAV-grafted one, could support cell proliferation and neurite outgrowth. The maleimide-functionalized poly(ester carbonate)s provide a versatile platform for diverse functionalization and have comprehensive potential in biomedical engineering. PMID:24962245

  18. Synthesis of poly(N-isopropylacrylamide) hydrogels by radiation polymerization and cross-linking

    SciTech Connect

    Nagaoka, Noriyasu; Kubota, Hitoshi; Katakai, Ryoichi; Safranj, Agneza; Yoshida, Masaru; Omichi, Hideki

    1993-12-20

    Poly(N-isopropylacrylamide) [poly(NIPAAm)] shows a typical thermal reversibility of phase transition in aqueous solutions. That is, it precipitates from solution above a critical temperature called the lower critical solution temperature (LCST) and dissolves below this temperature. When it is cross-linked, the obtained hydrogel collapses above LCST, while it swells and expands below LCST. This hydrogel has received much attention recently and has been used as a model system to demonstrate the validity of theories describing the coil-globule transition, swelling of networks, and folding and unfolding of biopolymers. It has also been proposed for various applications ranging from controlled drug delivery to solute separation. Poly(NIPAAm) hydrogel is usually synthesized at room temperature from an aqueous solution of the monomer by using a redox initiator composed of ammonium persulfate and N,N,N{prime},N{prime}-tetramethylethylenediamine in the presence of N,N{prime}-methylenebisacrylamide as a cross-linker. Since the LCST of poly(NIPAAm) is around 32 C, the polymerization at room temperature proceeds in a homogeneous solution. Recently, poly(NIPAAm) hydrogels were synthesized by starting the polymerization below the LCST and then elevating the temperature above it, by which method macroporous gels with fast temperature response were obtained. The idea is to apply a radiation--induced polymerization method for the synthesis of poly(NIPAAm) hydrogels. This method offers unique advantages for synthesis: it is a simple and additive-free process at all temperatures, and the degree of cross-linking can be easily controlled by irradiation conditions. Therefore, radiation methods are especially attractive for the synthesis of hydrogels with potential biomedical application where the residual chemical initiators may contaminate the product. It is possible to combine into one step the synthesis and sterilization of the product, and it is economically competitive.

  19. Onium salt structure/property relationships in poly(4-tert-butyloxycarbonyloxystyrene) deep-UV resists

    NASA Astrophysics Data System (ADS)

    Schwartzkopf, George; Niazy, Nagla N.; Das, Siddhartha; Surendran, Geetha; Covington, John B.

    1991-06-01

    A series of sulfonium and iodonium salts was synthesized and the effect of onium slat structure on UV absorbance, thermal stability, and solubility in propylene glycol methyl ether acetate (PGMEA) was assessed. Several of these onium salts gave usable deep UV photoresists when combined with poly(4-tert-butyloxy-carbonloxystyrene). The lithographic sensitivity and latent image stability of these photoresists were strongly influenced by the structure of the incorporated onium salt.

  20. Single-Strand Regions of Poly(G) Act as Templates for Oligo(C) Synthesis

    NASA Technical Reports Server (NTRS)

    Rembold, Hansjorg; Oregel, Leslie E.

    1994-01-01

    Oligonucleotide primers consisting of a sequence of four or more deoxycytidylate residues terminated by a single ribocytidylate residue are extended by reaction with cytidine 5-phosphoro(2-methyl)imidazolide using polyguanylic acid as a template. The efficiency of the reaction decreases as the length of the primer increases. The reaction does not seem to depend on the dissociation of poly(G) tetrahelices but uses as templates single-stranded segments that are already present in enzymatically synthesized polyguanylic acid.

  1. Metallosupramolecular poly[2]pseudorotaxane constructed by metal coordination and crown-ether-based molecular recognition.

    PubMed

    Wei, Peifa; Li, Jinying; Yan, Xuzhou; Zhou, Qizhong

    2014-01-01

    A novel bis(m-phenylene)-32-crown-10 derivative bearing two π-extended pyridyl groups was synthesized, and its host-guest complexation with a paraquat derivative to form a threaded [2]pseudorotaxane was studied. Subsequently, a poly[2]pseudorotaxane was constructed with a metallosupramolecular polymer backbone via metal coordination, which was comprehensively confirmed by the combination of (1)H NMR, (31)P{(1)H} NMR, DOSY NMR, DLS, and EDX techniques. PMID:24328434

  2. Controlled drug release from hydrogel nanoparticle networks.

    PubMed

    Huang, Gang; Gao, Jun; Hu, Zhibing; St John, John V; Ponder, Bill C; Moro, Dan

    2004-02-10

    Monodisperse nanoparticles of poly-N-isopropylacrylamide-co-allylamine (PNIPAM-co-allylamine) and PNIPAM-co-acrylic acid (PNIPAM-co-AA) were synthesized. The close-packed PNIPAM-co-allylamine and PNIPAM-co-AA nanoparticles were converted to three-dimensional gel networks by covalently crosslinking neighboring particles at room temperature and neutral pH using glutaric dialdehyde and adipic acid dihydrazide, respectively. Controlled release studies were conducted using dextran markers of various molecular weights as model macromolecular drugs. Release was quantified under various physical conditions, including a range of temperatures and dextran molecular weights. Dextran, entrapped in cavities in the nanoparticle network, was released with a rate regulated by their molecular weights and cavity size. No release from a conventional bulk PNIPAM gel, with high crosslinking density, was observed. The rate of release from the PNIPAM-co-allylamine network was temperature-dependent, being much faster at room temperature than that at human body temperature. In contrast, release of low molecular weight dextrans from the PNIPAM-co-AA network showed a temperature-independent release profile. These nanoparticle networks have several advantages over conventional bulk gels for controlling the release of high molecular weight biomolecules. PMID:14744482

  3. VCO PLL Frequency Synthesizers for Spacecraft Transponders

    NASA Technical Reports Server (NTRS)

    Smith, Scott; Mysoor, Narayan; Lux, James; Cook, Brian

    2007-01-01

    Two documents discuss a breadboard version of advanced transponders that, when fully developed, would be installed on future spacecraft to fly in deep space. These transponders will be required to be capable of operation on any deepspace- communications uplink frequency channel between 7,145 and 7,235 MHz, and any downlink frequency channel between 8,400 and 8,500 MHz. The document focuses on the design and operation of frequency synthesizers for the receiver and transmitter. Heretofore, frequency synthesizers in deep-space transponders have been based on dielectric resonator oscillators (DROs), which do not have the wide tuning bandwidth necessary to tune over all channels in the uplink or downlink frequency bands. To satisfy the requirement for tuning bandwidth, the present frequency synthesizers are based on voltage-controlled-oscillator (VCO) phase-locked loops (PLLs) implemented by use of monolithic microwave integrated circuits (MMICs) implemented using inGaP heterojunction bipolar transistor (HBT) technology. MMIC VCO PLL frequency synthesizers similar to the present ones have been used in commercial and military applications but, until now, have exhibited too much phase noise for use in deep-space transponders. The present frequency synthesizers contain advanced MMIC VCOs, which use HBT technology and have lower levels of flicker (1/f) phase noise. When these MMIC VCOs are used with high-speed MMIC frequency dividers, it becomes possible to obtain the required combination of frequency agility and low phase noise.

  4. Development of automatic hologram synthesizer for medical use II: hologram synthesizing machine and viewer

    NASA Astrophysics Data System (ADS)

    Suzuki, Masane; Saito, Takayuki

    1992-05-01

    Hologram synthesizing machine as a key component of the automatic hologram synthesizer is developed. Hologram synthesizing machine creates cylindrical multiplex holograms with 400 mm diameter from images displayed on liquid crystal SLM or images on 35 mm cine film. The machine consists of a main body, a controller, and a film processing machine, and performs synthesis and chemical processing of hologram automatically within 4 hours. A viewer which reconstructs original images from a synthesized hologram is also developed. In addition to reconstruction of images, the viewer also can point and measure images.

  5. Stereocomplexation of low molecular weight poly(L-lactic acid) and high molecular weight poly(D-lactic acid), radiation crosslinking PLLA/PDLA stereocomplexes and their characterization

    NASA Astrophysics Data System (ADS)

    Quynh, Tran Minh; Mai, Hoang Hoa; Lan, Pham Ngoc

    2013-02-01

    Poly(L-lactic acid)s (PLLAx) were synthesized from L-lactic acid by polycondensation. Different stereocomplexes were also obtained with equimolar mixtures of synthesized PLLAx and a commercial PDLA. The stereocomplexes were crosslinked with triallyl isocyanurate (TAIC) by gamma irradiation. Crosslinking density increased with radiation doses, the heavier the crosslinking network, the lower its swelling degree. The crosslinking structures were introduced in the stereocomplexes inhibiting the mobility for crystallization of PLLA molecules. Thermal and mechanical properties of PLA stereocomplexes were remarkably enhanced by radiation induced crosslinking. PLA stereocomplex does not seem to be degraded by PLLA degrading microorganisms existing in compost at room temperature, but the synthesized PLLA was significantly degraded.

  6. Synthesis and self-assembly of amphiphilic poly(acrylicacid)-poly(ɛ-caprolactone)-poly(acrylicacid) block copolymer as novel carrier for 7-ethyl-10-hydroxy camptothecin.

    PubMed

    Djurdjic, Beti; Dimchevska, Simona; Geskovski, Nikola; Petrusevska, Marija; Gancheva, Valerya; Georgiev, Georgi; Petrov, Petar; Goracinova, Katerina

    2015-01-01

    The process of molecular self-assembly plays a crucial role in formulation of polymeric nanoparticulated drug delivery carriers as it creates the possibility for enhanced drug encapsulation and carrier surface engineering. This study aimed to develop a novel self-assembled polymeric micelles for targeted delivery in tumor cells in order to overcome not only various drawbacks of 7-ethyl-10-hydroxy camptothecin (SN-38) but also various reported limitations of other drug delivery systems, especially low drug loading and premature release. Custom synthesized amphiphilic triblock copolymer poly(acrylic acid)-poly(ɛ-caprolactone)-poly(acrylic acid) (PAA(13)-PCL(35)-PAA(13)) was used to prepare kinetically stable micelles by nanoprecipitation and modified nanoprecipitation procedure. Core-shell micelles with diameter of 120-140 nm, negative zeta potential and satisfactory drug loading were produced. The prepared formulations were stable in pH range of 3-12 and in media with NaCl concentration <1 mol/l. Screening mixed level factorial 3 × 2(2) design identified that the process temperature as well as the type of organic solvent has influence upon the efficacy of encapsulation, particle size, dissolution rate and burst release. Fourier transform infrared and differential scanning calorimetry analyses confirmed the entrapment of the active substance into the micelles. The kinetic analysis of dissolution studies revealed that the main mechanism of drug release from the prepared formulations is Fickian diffusion. Growth inhibition studies as well as DNA fragmentation assay performed on SW-480 cell lines clearly demonstrated increased growth inhibition effect and presence of fragmented DNA in cells treated with loaded micelles compared to SN-38 solution. Altogether, these results point out to potential biomedical and clinical application of PAA-PCL-PAA systems in the future. PMID:25209880

  7. Poly-3-hydroxy butyric acid interaction with the transgenic flax fibers: FT-IR and Raman spectra of the composite extracted from a GM flax.

    PubMed

    Wróbel-Kwiatkowska, Magdalena; Zuk, Magdalena; Szopa, Jan; Dymińska, Lucyna; Maczka, Mirosław; Hanuza, Jerzy

    2009-07-15

    The FT-IR and FT-Raman studies have been performed on commercial 3-hydroxy-butyric acid, commercial poly-3-hydroxy butyric acid as well as poly-3-hydroxy butyric acid (PHB) produced by bacteria. The data were compared to those obtained for poly-3-hydroxy butyric acid extracted from natural and genetically modified flax. Genetically modified flax was generated by expression of three bacterial genes coding for synthesis of poly-3-hydroxy butyric acid. Thus transgenic flaxes were enhanced with different amount of the PHB. The discussion of polymer structure and vibrational properties has been done in order to get insight into differences among these materials. The interaction between the cellulose of flax fibers and embedded poly-3-hydroxybutyric acid has been also discussed. The spectroscopic data provide evidences for structural changes in cellulose and in PHB when synthesized in fibers. Based on this data it is suggesting that cellulose and PHB interact by hydrogen and ester bonds. PMID:19328737

  8. Poly-3-hydroxy butyric acid interaction with the transgenic flax fibers: FT-IR and Raman spectra of the composite extracted from a GM flax

    NASA Astrophysics Data System (ADS)

    Wróbel-Kwiatkowska, Magdalena; Żuk, Magdalena; Szopa, Jan; Dymińska, Lucyna; Mączka, Mirosław; Hanuza, Jerzy

    2009-07-01

    The FT-IR and FT-Raman studies have been performed on commercial 3-hydroxy-butyric acid, commercial poly-3-hydroxy butyric acid as well as poly-3-hydroxy butyric acid (PHB) produced by bacteria. The data were compared to those obtained for poly-3-hydroxy butyric acid extracted from natural and genetically modified flax. Genetically modified flax was generated by expression of three bacterial genes coding for synthesis of poly-3-hydroxy butyric acid. Thus transgenic flaxes were enhanced with different amount of the PHB. The discussion of polymer structure and vibrational properties has been done in order to get insight into differences among these materials. The interaction between the cellulose of flax fibers and embedded poly-3-hydroxybutyric acid has been also discussed. The spectroscopic data provide evidences for structural changes in cellulose and in PHB when synthesized in fibers. Based on this data it is suggesting that cellulose and PHB interact by hydrogen and ester bonds.

  9. Radiolytic syntheses of nanoparticles in supramolecular assemblies.

    PubMed

    Chen, Qingde; Shen, Xinghai; Gao, Hongcheng

    2010-08-11

    Ionizing radiation is a powerful method in the syntheses of nanoparticles (NPs). The application of ionizing radiation in supramolecular assemblies can afford us more unique conditions to control the composition and morphology of the NPs. So far, most work focused on water-in-oil (W/O) microemulsions or reversed micelles. In this supramolecular organization, it has been proved that the effects of many conditions on the yield of e(aq)(-) play a key role, remarkably different from the mechanism in routine chemical method. Besides, some supramolecular assemblies of cyclodextrins and ionic liquids have been used in the syntheses of NPs by ionizing radiation, and many novel and interesting phenomena appeared. This review is intended to underline the three significant aspects of the radiolytic syntheses of NPs in supramolecular assemblies. PMID:20653087

  10. Investigation of the doping efficiency of poly(styrene sulfonic acid) in poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonic acid) dispersions by capillary electrophoresis.

    PubMed

    Diah, Anang W M; Quirino, Joselito P; Belcher, Warwick; Holdsworth, Clovia I

    2014-07-01

    CE can efficiently separate poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS) complexes and free PSS in dispersions and can be used to estimate the degree of PSS doping. We investigated the doping efficiency of PSS on PEDOT in dispersions using CE and its effect on the conductivity of the resulting PEDOT/PSS films. Results of this study indicate that dispersions containing 1:2.5-3 EDOT:PSS feed ratio (by weight) exhibiting 72-73% PSS doping generate highly processable and highly conductive films. Conductivity can be optimized by limiting the time of reaction to 12 h. At this point of the reaction, the PEDOT/PSS segments, appearing as broad band in the electropherogram, could still exist in an extended coil conformation favoring charge transport resulting in high conductivity. Above a threshold PEDOT length formed at reaction times longer than 12 h, the PEDOT/PSS complex, appearing as spikes in the electropherogram, most likely have undergone a conformational change to coiled core-shell structure restricting charge transport resulting in low conductivity. The optimal conductivity (5.2 S/cm) of films from dispersions synthesized for 12 h is significantly higher than those from its commercial equivalent Clevios P and other reported values obtained under similar conditions without the addition of codopants. PMID:24782292

  11. Water-Soluble Poly(L-serine)s with Elongated and Charged Side-Chains: Synthesis, Conformations and Cell-Penetrating Properties

    PubMed Central

    Tang, Haoyu; Yin, Lichen; Lu, Hua; Cheng, Jianjun

    2012-01-01

    Water-soluble poly(L-serine)s bearing long side-chain with terminal charge groups were synthesized via ring-opening polymerization of O-pentenyl-L-serine N-carboxyanhydride followed by thiol-ene reactions. These side-chain modified poly(L-serine)s adopt β-sheet conformation in aqueous solution with excellent stability against changes in pH and temperature. These water-soluble poly(L-serine) derivatives with charged side-chain functional groups and stable β-sheet conformations showed membrane-penetrating capabilities in different cell lines with low cytotoxicity. PMID:22853191

  12. Infrared properties of electrochemically synthesized PEDOT and PProDOT films

    NASA Astrophysics Data System (ADS)

    Hwang, J.; Tanner, D. B.; Giurgiu, I.; Reynolds, J. R.

    2000-03-01

    We report the infrared properties of electrochemically synthesized poly(3,4-ethlyenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT) thin films on metallic substrates. We study also electrochromic cells of PEDOT. The cell consists of a 1mm ZnSe window, electrolyte gel (ELG) layer, PEDOT film on a multislit gold-Mylar tape, ELG/separating paper/ELG, and poly(3,6-bis(2-(3,4-EDOT))-N-methylcarbazole) film on gold-Mylar tape. The reflectance of the cell shows a large contrast between the neutral and doped forms in the spectral range from 1,900 to 14,000 cm-1. We also report reflectance and transmittance of PEDOT and PProDOT on ITO/Glass substrates and the optical constants of PEDOT and PProDOT from fits to reflectance and tranmittance data. The PEDOT and PProDOT films are similar. The doped films have stronger midinfrared and near-infrared absorptions but weaker visible absorption. We will discuss applications of the electrochromic cells.

  13. Total Syntheses of Periconiasins A-E.

    PubMed

    Tian, Chong; Lei, Xiaoqiang; Wang, Yuanhao; Dong, Zhen; Liu, Gang; Tang, Yefeng

    2016-06-01

    The first and collective total syntheses of periconiasins A-E, a group of naturally occurring cytochalasans, were achieved by a series of rationally designed or bioinspired transformations. Salient features of the syntheses include a tandem aldol condensation/Grob fragmentation to assemble the linear polyketide-amino acid hybrid precursor, a Diels-Alder macrocylization to construct the 9/6/5 tricyclic core of periconiasins A-C, and a transannular carbonyl-ene reaction to forge the polycyclic framework of periconiasins D and E. PMID:27121397

  14. Synthesize, Synthesize, Synthesize.

    ERIC Educational Resources Information Center

    Nugent, Susan Monroe, Ed.

    1987-01-01

    Focusing on synthesis--the ability to recognize and create new ideas that subsume and relate to others--as one of the most sophisticated skills writers can attain, the articles in this journal present many ideas for teaching synthesis and a number of classroom approaches that combine the study of English with other fields. The following titles and…

  15. Complex Polymeric Architectures Synthesized and Functionalized using Robust Chemistries

    NASA Astrophysics Data System (ADS)

    Killops, Kathryn L.

    Niche applications for polymeric materials put stringent requirements on their properties and architecture. Although polymer synthesis techniques have improved significantly to produce well-defined materials with narrow molecular weight distributions from a variety of monomeric precursors, the final materials often require fine-tuning of the structure or functionality to achieve the properties necessary for a given high performance application. The ability to modify and synthesize soft materials in precise and predictable manner requires the use of robust, efficient, and orthogonal chemistries. The highly branched structure of dendrimers provides an ideal platform to rigorously evaluate the ability of a reaction to proceed with quantitative conversion and high specificity. In order to achieve a macromolecular structure having a monodisperse molecular weight of over 10,000 Da, highly efficient reactions must be used. The synthesis of dendrimers up to the fourth generation was accomplished using successive iterations of thiol--ene 'click' chemistry and esterification reactions. The high molecular weight dendrimers were subsequently derivitized at the periphery using a variety of functional groups to demonstrate the orthogonality of the thiol--ene reaction. An extension of this work provided direct comparison of the thermally- and photochemically-initiated thiol--ene reactions, as applied to the functionalization of polymers both along the backbone and at the chain ends. With block copolymers, access to nanoscale features is afforded by the propensity of two chemically-distinct, covalently-linked polymer chains phase separate into discrete domains. These nanoscopic features have important implications for high performance applications like microelectronics and water purification. Precise modification of these structures expands the number of applications that could benefit from their implementation. In the search for a poly(ethylene oxide)-based nanoparticle with

  16. [Removal Congo Red from Aqueous Solution Using Poly (AM-co-DVB)].

    PubMed

    Zhang, Luan-luan; Liao, Yun-wen; Gao, He-jun; Wang, Zhong-zhi; Shuai, Chao

    2015-06-01

    Poly(AM-co-DVB) was synthesized by acrylamide(AM) and divinylbenzene(DVB) via the crosslinking reaction. The microscope structure and thermal stability of Poly(AM-co-DVB) were characterized by FT-IR, SEM and TG. Congo red (CR) was used to measure the adsorptive capacity of Poly (AM-co-DVB). The effects of initial pH, contact time and temperature on the adsorption of CR on Poly (AM-co-DVB) were investigated in this work. The kinetics, equilibrium, and thermodynamics of the adsorption process were also discussed. The results showed that the maximum adsorption capacities were 319.1 mg x g(-1) at pH = 7.25 and contact time = 3 h. The adsorption kinetics was well fitted by a pseudo-second-order model and the adsorption isotherms agreed well with the Langmuir model. The adsorption process was spontaneous process. Above all, the adsorption capacity of Poly (AM-co-DVB) on Congo red is significant. PMID:26387325

  17. Magnetic poly(PEGMA-MAA) nanoparticles: photochemical preparation and potential application in drug delivery.

    PubMed

    Sun, Han-Wen; Zhang, Lian-Ying; Zhu, Xin-Jun; Wang, Xin-Fang

    2009-01-01

    Poly(PEGMA-MAA)-coated superparamagnetic nanoparticles were synthesized by in situ photochemical polymerization in magnetite aqueous suspension under UV irradiation. The magnetic poly(PEGMA-MAA) nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), photo correlation spectroscopy (PCS) and vibration sample magnetometry (VSM), respectively. The results indicated that the magnetic poly(PEGMA-MAA) nanoparticles were of regularly spherical shape and remained monodisperse. The average size measured in aqueous media was 96.4 nm, which was much bigger than that in dry state, the nanoparticles behaved superparamagnetic with saturated magnetization of 64.8 emu/g, the zeta potential was -18.3 mV at physiological pH 7.2, and the magnetic poly(PEGMA-MAA) nanoparticles had a high stability in vitro. A typical anti-inflammatory drug, ibuprofen, was used for drug loading, and the release behavior of ibuprofen in a simulated body fluid (SBF, pH 7.4) was studied. The results indicated that these novel magnetic nanoparticles had a high drug-loading capacity and favorable release properties for ibuprofen. The magnetic poly(PEGMA-MAA) nanoparticles are very promising for application in drug delivery. PMID:19723435

  18. Supramolecular gels of poly-α-cyclodextrin and PEO-based copolymers for controlled drug release.

    PubMed

    Simões, Susana M N; Veiga, Francisco; Ribeiro, Ana C F; Figueiras, Ana R; Taboada, Pablo; Concheiro, Angel; Alvarez-Lorenzo, Carmen

    2014-08-01

    The aim of this work was to prepare syringeable supramolecular gels of α-cyclodextrin-polymer (poly-αCD) with various poly(ethylene oxide) (PEO)-based copolymers, which can be suitable to form depots for controlled drug release. A series of water-soluble poly-αCDs was synthesized from αCD by crosslinking with epichlorohydrin in alkaline medium. The chemical composition of the polymers was characterized by NMR (αCD content>53%) and the molecular weight was evaluated using static light scattering (SLS). Supramolecular assemblies occurred by mixing poly-αCD (20-40% w/v) with a PEO-based polymer (i.e., PEG, Pluronic® F127 or Tetronic® 908) (10-15% w/v). Phase separation was observed and the αCD content in each phase was determined by means of the phenol-sulfuric acid colorimetric method. Formation of poly-αCD/PEO-based polymer 3D-supramolecular complexes was confirmed by diffusion-ordered NMR spectroscopy (DOSY) and X-ray diffractometry. The supramolecular assemblies showed good cytocompatibility against SAOS-2 cells and in the HET-CAM test. The supramolecular gels were able to sustain the release of vancomycin for at least 5 days at 37 °C, more efficiently than dispersions of each polymer component in separate. These results open new possibilities in the design of novel controlled delivery systems for the treatment of bone infections. PMID:24769064

  19. Helical Poly(5-alkyl-2,3-thiophene)s: Controlled Synthesis and Structure Characterization

    DOE PAGESBeta

    Zhang, Hong-Hai; Ma, Chuanxu; Bonnesen, Peter V.; Zhu, Jiahua; Sumpter, Bobby G.; Carrillo, Jan-Michael Y.; Yin, Panchao; Wang, Yangyang; Li, An-Ping; Hong, Kunlun

    2016-07-12

    Whereas Poly(3-alkyl-2,5-thiophene)s (P3AT), with many potential applications, have been extensively investigated, their ortho-connected isomers, poly(5-alkyl-2,3-thiophene)s (P5AT), have never been reported because of the difficulty in their syntheses. We herein present the first synthesis of regioregular P5AT via controlled Suzuki cross-coupling polymerization with PEPPSI-IPr as catalyst, affording the polymers with tunable molecular weight, narrow polydispersity (PDI) and well-defined functional end groups at the gram scale. The helical geometry of P5AT was studied by a combination of NMR, small angle x-ray scattering (SAXS) and scanning tunneling microscopy (STM). Particularly, the single polymer chain of poly(5- 2 butyl-2,3-thiophene) (P5BT) on highly oriented pyrolyticmore » graphite (HOPG) substrates with either M or P helical conformation was directly observed by STM. The comparison of UV-vis absorption between poly(5-hexyl-2,3-thiophene) (P5HT) (λ = 345 nm) and poly(3-hexyl-2,5- thiophene) (P3HT) (λ = 450 nm) indicated that the degree of conjugation of the backbone in P5HT is less than in P3HT, which may be a consequence of the helical geometry of the former compared to the more planar geometry of the latter. Moreover, we found that P5HT can emit green fluorescence under UV (λ = 360 nm) irradiation« less

  20. Poly(ADP-ribose) metabolism in young and old cells: response to cellular stresses

    SciTech Connect

    Gracy, R.W.; Sims, J.L.; Cini, J.

    1986-05-01

    The authors have examined the effect of several cellular stresses on poly(ADP-ribose) metabolism in human fibroblasts of low passage number derived from young and old donors. Poly(ADP-ribose) was synthesized in response to alkylation of DNA caused by N-methyl-N'-nitro-N-nitroguanidine and by hyperthermic treatment at 43 /sup 0/C or 45 /sup 0/C. Ethanol is able to potentiate poly(ADP-ribose) accumulation following these treatments. There was little if any difference in the response of young and old cells to these stresses. Amino acid analogs are thought to induce a response in mammalian cells similar to that caused by hyperthermia and ethanol. However, amino acid analogs such as L-azetidine did not produce effects on poly(ADP-ribose) metabolism like those produced by ethanol or hyperthermia. The authors have also examined the poly(ADP-ribose) content of bovine eye lens. Each eye lens contains populations of young and old cells that are distributed in a fixed graduated manner. Thus, the eye lens allows the study of aging cells with identical genetic backgrounds without the complications of serial passage of young cultures in in vitro aging systems.

  1. Hydrophobic poly(alkoxysilane) organogels as sorbent material for oil spill cleanup.

    PubMed

    Ozan Aydin, Gulsah; Bulbul Sonmez, Hayal

    2015-07-15

    In this study, reusable poly(alkoxysilane) organogels with high absorption capacities were synthesized by the condensation of a cyclo aliphatic glycol (UNOXOL™) and altering the chain length of the alkyltriethoxysilanes. The structural and thermal properties of cross-linked poly(alkoxysilane) polymers were determined by FTIR, solid-state (13)C and (29)Si CPMAS NMR and TGA. The oil absorbency of poly(alkoxysilane)s was determined through oil absorption tests, absorption and desorption kinetics. Results showed that the highest oil absorbency capacities were found to be 295% for hexane, 389% for euro diesel, 428% for crude oil, 652% for gasoline, 792% for benzene, 792% for toluene, 868% for tetrahydrofuran, and 1060% for dichloromethane for the poly(alkoxysilane) gels based on UNOXOL™ and dodecyltriethoxysilane. Owing to their hydrophobic structure, the poly(alkoxysilane) organogels can selectively absorb crude oil from water. The reusability of the absorbents was quantitatively investigated, demonstrating that absorbents can be used effectively at least nine times. PMID:26002096

  2. Synthesis, characterization and biological application of four novel metal-Schiff base complexes derived from allylamine and their interactions with human serum albumin: Experimental, molecular docking and ONIOM computational study.

    PubMed

    Kazemi, Zahra; Rudbari, Hadi Amiri; Sahihi, Mehdi; Mirkhani, Valiollah; Moghadam, Majid; Tangestaninejad, Shahram; Mohammadpoor-Baltork, Iraj; Gharaghani, Sajjad

    2016-09-01

    Novel metal-based drug candidate including VOL2, NiL2, CuL2 and PdL2 have been synthesized from 2-hydroxy-1-allyliminomethyl-naphthalen ligand and have been characterized by means of elemental analysis (CHN), FT-IR and UV-vis spectroscopies. In addition, (1)H and (13)C NMR techniques were employed for characterization of the PdL2 complex. Single-crystal X-ray diffraction technique was utilized to characterise the structure of the complexes. The Cu(II), Ni(II) and Pd(II) complexes show a square planar trans-coordination geometry, while in the VOL2, the vanadium center has a distorted tetragonal pyramidal N2O3 coordination sphere. The HSA-binding was also determined, using fluorescence quenching, UV-vis spectroscopy, and circular dichroism (CD) titration method. The obtained results revealed that the HSA affinity for binding the synthesized compounds follows as PdL2>CuL2>VOL2>NiL2, indicating the effect of metal ion on binding constant. The distance between these compounds and HSA was obtained based on the Förster's theory of non-radiative energy transfer. Furthermore, computational methods including molecular docking and our Own N-layered Integrated molecular Orbital and molecular Mechanics (ONIOM) were carried out to investigate the HSA-binding of the compounds. Molecular docking calculation indicated the existence of hydrogen bond between amino acid residues of HSA and all synthesized compounds. The formation of the hydrogen bond in the HSA-compound systems leads to their stabilization. The ONIOM method was utilized in order to investigate HSA binding of compounds more precisely in which molecular mechanics method (UFF) and semi empirical method (PM6) were selected for the low layer and the high layer, respectively. The results show that the structural parameters of the compounds changed along with binding to HSA, indicating the strong interaction between the compounds and HSA. The value of binding constant depends on the extent of the resultant changes. This

  3. Influence of poly(ethylene glycol) as pore-generator on morphology and performance of chitosan/poly(vinyl alcohol) membrane adsorbents

    NASA Astrophysics Data System (ADS)

    Salehi, E.; Madaeni, S. S.

    2014-01-01

    Macroporous chitosan/poly(vinyl alcohol) membrane adsorbents were synthesized by solvent evaporation in the presence of poly(ethylene glycol) which was utilized as porogen. The membranes were applied for Cu(II) ion adsorption from water. SEM, AFM and wettability analyses were performed for membrane characterization. Insertion of poly(ethylene glycol) generated macrovoids in the dense structure of CS/PVA membranes through particulate leaching out mechanism. According to the static adsorption tests, the uptake capacity of the porous membranes is elevated (˜26 mg/g) compared to that of the dense membranes (˜10 mg/g). This phenomenon is attributed to the increase in the density of active sites, water affinity and surface roughness as a result of the porogen effects. The approachability of the ions to the active sites was also affected by these important parameters. Both size and density of the macrovoids increased with increasing PEG content from nil to 5 wt%. Fragility of the resultant porous structures prohibited synthesizing CS/PVA membranes with higher porogen contents. Desorption tests showed that the porous membranes were better regenerated in comparison to the dense membranes using Na2EDTA as eluant. Generally, the results suggested that the CS/PVA membranes, comprising PEG as pore-generator agent, are potential candidates for adsorption and elimination of Cu(II) ions from water.

  4. Synthesizing Diacetylenes With Nonlinear Optical Properties

    NASA Technical Reports Server (NTRS)

    Mcmanus, Samuel P.; Frazier, Donald P.; Paley, Mark S.

    1993-01-01

    Diacetylene compounds being investigated to determine whether they have nonlinear optical properties making them useful for four-wave mixing, generation of third harmonics, phase conjugation, and like. Diacetylene monomers synthesized by sequences of chemical reactions. Monomers polymerized by ultraviolet light, forming potentially useful nonlinear optical materials.

  5. Evaluating Text-to-Speech Synthesizers

    ERIC Educational Resources Information Center

    Cardoso, Walcir; Smith, George; Fuentes, Cesar Garcia

    2015-01-01

    Text-To-Speech (TTS) synthesizers have piqued the interest of researchers for their potential to enhance the L2 acquisition of writing (Kirstein, 2006), vocabulary and reading (Proctor, Dalton, & Grisham, 2007) and pronunciation (Cardoso, Collins, & White, 2012; Soler-Urzua, 2011). Despite their proven effectiveness, there is a need for…

  6. Issues in Synthesizing Research in Education

    ERIC Educational Resources Information Center

    Andrews, Richard; Harlen, Wynne

    2006-01-01

    Background: Systematic reviews of educational research require synthesis of the results from a range of studies. When these studies are diverse in nature and methodological approach, synthesis can be problematic. Purpose: To offer a critique of the process of synthesizing systematic reviews by considering the stages of the process and the problems…

  7. Method and apparatus for synthesizing filamentary structures

    DOEpatents

    Height, Murray J.; Howard, Jack B.; Vandersande, John B.

    2008-02-26

    Method and apparatus for producing filamentary structures. The structures include single-walled nanotubes. The method includes combusting hydrocarbon fuel and oxygen to establish a non-sooting flame and providing an unsupported catalyst to synthesize the filamentary structure in a post-flame region of the flame. Residence time is selected to favor filamentary structure growth.

  8. Digital Frequency Synthesizer For Radar Astronomy

    NASA Technical Reports Server (NTRS)

    Sadr, Ramin; Satorius, Edgar; Robinett, J. Loris, Jr.; Olson, Erlend

    1992-01-01

    Report discusses conceptual digital frequency synthesizer part of programmable local oscillator in radar-astronomy system. Phase must remain continuous during adjustments of frequency, phase noise must be low, and spectral purity must be high. Discusses theory of operation in some mathematical detail and presents new analysis of spectral purity of output.

  9. Syntheses of novel substituted-boranophosphate nucleosides.

    PubMed

    Vyakaranam, Kamesh; Rana, Geeta; Spielvogel, Bernard F; Maguire, John A; Hosmane, Narayan S

    2002-01-01

    A number of substituted (borano) nucleic acids, 3'-[diethylphosphite(cyano, carboxy, or carbamoyl) borano] deoxynucleosides (3a-4c) and 5'-[diethylphosphite(cyano or carboxy) borano] deoxynucleosides (6a-7d) were prepared by a variety of synthetic procedures. The syntheses of the pyrophosphates (2a-2c), as precursors for 3a-4c, are also described. PMID:12484452

  10. Syntheses of Arnottin I and Arnottin II

    PubMed Central

    Moschitto, Matthew J.; Anthony, David R.; Lewis, Chad A.

    2015-01-01

    Short total syntheses of arnottin I and II were accomplished in 5 and 6 steps, respectively. A sesamol-benzyne cycloaddition with a 3-furyl-benzoate followed by regiospecific lactonization provided rapid, large-scale access to the core of arnottin I. Saponification of arnottin I and hypervalent iodide mediated spirocyclization provided an efficient and direct preparation of racemic arnottin II. PMID:25748275

  11. Zwitterionic Poly(amino acid methacrylate) Brushes

    PubMed Central

    2014-01-01

    A new cysteine-based methacrylic monomer (CysMA) was conveniently synthesized via selective thia-Michael addition of a commercially available methacrylate-acrylate precursor in aqueous solution without recourse to protecting group chemistry. Poly(cysteine methacrylate) (PCysMA) brushes were grown from the surface of silicon wafers by atom-transfer radical polymerization. Brush thicknesses of ca. 27 nm were achieved within 270 min at 20 °C. Each CysMA residue comprises a primary amine and a carboxylic acid. Surface zeta potential and atomic force microscopy (AFM) studies of the pH-responsive PCysMA brushes confirm that they are highly extended either below pH 2 or above pH 9.5, since they possess either cationic or anionic character, respectively. At intermediate pH, PCysMA brushes are zwitterionic. At physiological pH, they exhibit excellent resistance to biofouling and negligible cytotoxicity. PCysMA brushes undergo photodegradation: AFM topographical imaging indicates significant mass loss from the brush layer, while XPS studies confirm that exposure to UV radiation produces surface aldehyde sites that can be subsequently derivatized with amines. UV exposure using a photomask yielded sharp, well-defined micropatterned PCysMA brushes functionalized with aldehyde groups that enable conjugation to green fluorescent protein (GFP). Nanopatterned PCysMA brushes were obtained using interference lithography, and confocal microscopy again confirmed the selective conjugation of GFP. Finally, PCysMA undergoes complex base-catalyzed degradation in alkaline solution, leading to the elimination of several small molecules. However, good long-term chemical stability was observed when PCysMA brushes were immersed in aqueous solution at physiological pH. PMID:24884533

  12. Zwitterionic poly(amino acid methacrylate) brushes.

    PubMed

    Alswieleh, Abdullah M; Cheng, Nan; Canton, Irene; Ustbas, Burcin; Xue, Xuan; Ladmiral, Vincent; Xia, Sijing; Ducker, Robert E; El Zubir, Osama; Cartron, Michael L; Hunter, C Neil; Leggett, Graham J; Armes, Steven P

    2014-07-01

    A new cysteine-based methacrylic monomer (CysMA) was conveniently synthesized via selective thia-Michael addition of a commercially available methacrylate-acrylate precursor in aqueous solution without recourse to protecting group chemistry. Poly(cysteine methacrylate) (PCysMA) brushes were grown from the surface of silicon wafers by atom-transfer radical polymerization. Brush thicknesses of ca. 27 nm were achieved within 270 min at 20 °C. Each CysMA residue comprises a primary amine and a carboxylic acid. Surface zeta potential and atomic force microscopy (AFM) studies of the pH-responsive PCysMA brushes confirm that they are highly extended either below pH 2 or above pH 9.5, since they possess either cationic or anionic character, respectively. At intermediate pH, PCysMA brushes are zwitterionic. At physiological pH, they exhibit excellent resistance to biofouling and negligible cytotoxicity. PCysMA brushes undergo photodegradation: AFM topographical imaging indicates significant mass loss from the brush layer, while XPS studies confirm that exposure to UV radiation produces surface aldehyde sites that can be subsequently derivatized with amines. UV exposure using a photomask yielded sharp, well-defined micropatterned PCysMA brushes functionalized with aldehyde groups that enable conjugation to green fluorescent protein (GFP). Nanopatterned PCysMA brushes were obtained using interference lithography, and confocal microscopy again confirmed the selective conjugation of GFP. Finally, PCysMA undergoes complex base-catalyzed degradation in alkaline solution, leading to the elimination of several small molecules. However, good long-term chemical stability was observed when PCysMA brushes were immersed in aqueous solution at physiological pH. PMID:24884533

  13. Preparation and Biophysical Characterization of Poly(amidoamine) Dendrimer-Poly(acrylic acid) Graft.

    PubMed

    Dung, Tran Huu; Do, Le Thanh; Loan, Ta Thi; Yoo, Hoon

    2015-01-01

    A series of PAMAM dendrimer generation 5-poly(acrylic acid) grafts were prepared to evaluate the potential use of dendritic grafts as a drug encapsulated nanocarrier. The structural features of the synthesized polymer graft were identified by FT-IR and 1H-NMR spectra and the biophysical properties were characterized by measuring its particle size and zeta potential. The prepared dendrimer G5-PAA grafts had particle size in the range of 600 to 900 nm and the size increased proportionally with the number of PAA on dendrimer surface. The electrostatic property of the dendrimer G5-PAA, carried out by HPLC reversed phase column analysis and the measurement of zeta potential, revealed that both migration time and zeta potential were dependent on the number of grafted PAA. The number of free amino groups on dendrimer G5-PAA, determined quantitatively by fluorescamine assay, was in a reverse order with the reaction mole ratio of dendrimer to PAA. In addition, dendrimer G5-PAA showed a pH-dependent solubility in aqueous solution with characteristic pH region of solubility, depending on the dendrimer generation. The observed biophysical properties indicate that PAMAM dendrimer G5-PAA is promising as a drug encapsulated nanocarrier. PMID:26328427

  14. A cell-specific poly(ethylene glycol) derivative with a wheat-like structure for efficient gene delivery.

    PubMed

    Li, Hanmei; Sun, Xun; Zhao, Dong; Zhang, Zhirong

    2012-11-01

    A novel anionic PEG derivative with a wheat-like structure, PEG-poly(AGE-Suc), was synthesized. The spikelet part of this polymer consisting of 9.3 pairs of carboxylic acid side chains was conjugated at one end of the PEG chain. The neutral linear PEG(1580) was designed as the stalk part to improve the biocompatibility of the vectors. The obtained polymer PEG-poly(AGE-Suc) was further modified by folate (FA) at the distal end to achieve the cell-specific targeting. It was confirmed that the negatively charged FA-PEG-poly(AGE-Suc) could coat the positively charged PEI 25K/DNA complex and form a ternary complex by electrostatic interaction. The addition of FA-PEG-poly(AGE-Suc) could change the positive charge of PEI 25K/DNA complexes to negative with no influence on the diameter. The ternary complex with the coat of FA-PEG-poly(AGE-Suc) could effectively condense DNA and protect it from degradation by DNase I. The nonspecific interaction between PEI 25K/DNA complexes and blood components was also significantly reduced by the addition of anionic PEG. The ternary complex PEI 25K/DNA/FA-PEG-poly(AGE-Suc) exhibited a 12-fold higher transfection efficiency on 293T cells compared to PEI 25K/DNA in the serum-containing medium. The competitive folate inhibition assay demonstrated that the higher transfection efficiency of PEI 25K/DNA/FA-PEG-poly(AGE-Suc) was attributed to the folate molecule conjugated to the distal end of FA-PEG-poly(AGE-Suc). The ternary complex PEI 25k/DNA/FA-PEG-poly(AGE-Suc) with low side effects and high transfection efficiency may be a novel effective gene delivery system. PMID:22957964

  15. Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid)/Poly(vinyl alcohol) IPN Hydrogel and Its Drug Controlled Release.

    PubMed

    Lu, Jingqiong; Li, Yinhui; Hu, Deng; Chen, Xiaoling; Liu, Yongmei; Wang, Liping; Zhao, Yansheng

    2015-01-01

    Modified poly(aspartic acid)/poly(vinyl alcohol) interpenetrating polymer network (KPAsp/PVA IPN) hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid) grafting 3-aminopropyltriethoxysilane (KH-550) and poly(vinyl alcohol) (PVA) as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability was analyzed by thermogravimetric analysis (TGA). The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN), and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid) and 62.5 wt% at pH = 7.4 (simulated intestinal fluid), respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery. PMID:26351630

  16. Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid)/Poly(vinyl alcohol) IPN Hydrogel and Its Drug Controlled Release

    PubMed Central

    Lu, Jingqiong; Li, Yinhui; Hu, Deng; Chen, Xiaoling; Liu, Yongmei; Wang, Liping; Zhao, Yansheng

    2015-01-01

    Modified poly(aspartic acid)/poly(vinyl alcohol) interpenetrating polymer network (KPAsp/PVA IPN) hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid) grafting 3-aminopropyltriethoxysilane (KH-550) and poly(vinyl alcohol) (PVA) as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability was analyzed by thermogravimetric analysis (TGA). The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN), and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid) and 62.5 wt% at pH = 7.4 (simulated intestinal fluid), respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery. PMID:26351630

  17. A putative interferon induced in hamsters by poly(I) . poly(C).

    PubMed

    Round, E M; Stebbing, N

    1981-01-01

    Encephalomyocarditis (EMC) virus causes lethal infection of hamsters against which poly(I) . poly(C) causes dose-dependent protection. In contrast, no antiviral effects occur with poly(I) . poly(C) against influenza virus infection of hamsters. Serum from poly(I) . poly(C) treated hamsters protects other hamsters against EMC virus infection with maximum protection with serum removed 3h after poly(I) . poly(C) treatment of the donor hamsters. In such assays the factor was found to be inactivated by trypsin and pH 2 and 56 degrees C for 1 hr. The serum factor did not confer protection against EMC virus infection of L-929, BHK, Hak or primary hamster embryo cells. The amount of poly(I) . poly(C) carried over into serum samples of poly(I) . poly(C) treated hamsters was insufficient to account for the antiviral effects. The antiviral serum factor is presumed to be a form of interferon despite the fact that it does not titrate in cell cultures and has a novel set of properties from those which describe known interferons. PMID:6180078

  18. Thermo- and pH-sensitive gel membranes based on poly-(acryloyl- L-proline methyl ester)- graft-poly(acrylic acid) for selective permeation of metal ions

    NASA Astrophysics Data System (ADS)

    Hasegawa, Shin; Ohashi, Hitoshi; Maekawa, Yasunari; Katakai, Ryoichi; Yoshida, Masaru

    2005-04-01

    Thermo- and pH-responsive gel membranes were synthesized by γ-ray grafting of pH-responsive poly(acrylic acid) (AAc) onto thermo-responsive polymer gel of acryloyl- L-proline methyl ester (A-ProOMe). The gel membranes of poly(A-ProOMe) with 15 mol% graft chains of AAc exhibited both thermo- and pH-responses. Under the condition (pH 6.0, 30°C) in which the thermo-sensitive unit shrinks and the pH-sensitive unit swells, the selective permeation of Li ion over Co and Ni ions can be achieved.

  19. Synthesis, characterization and cell compatibility of novel poly(ester urethane)s based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) prepared by melting polymerization.

    PubMed

    Chen, Zhifei; Cheng, Shaoting; Li, Zibiao; Xu, Kaitian; Chen, Guo-Qiang

    2009-01-01

    Novel tailor-made poly(ester urethane)s (PUs) based on microbial polyesters poly(3-hydroxybutyrate-co-4hydroxybutyrate) (P3HB4HB) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) were synthesized by melting polymerization (MP) using 1,6-hexamethylene diisocyanate (HDI) as a coupling agent. A comprehensive characterization using (1)H-NMR, Fourier transform infrared spectroscopy (FT-IR), gel-permeation chromatography (GPC), differential scanning calorimetry (DSC), mechanical properties, static water contact angles, cell proliferation using smooth muscle cells from rabbit aorta (RaSMCs) and immortalized human keratinocytes (HaCat), and blood coagulation behavior were conducted on the synthesized PUs films. DSC showed that PU samples had a low degree of crystallinity at room temperature and became fully amorphous after a melt-quenched process. The series of tailor-made PUs based on different mass ratios of P3HB4HB and PHBHHx revealed a ductile and flexile mechanical property especially for PHBHHx-rich PU, or a hydrophobic property for 4HB-rich PU. A 4 days incubation experiment showed that all PU films had a better cell proliferation than poly(lactic acid) (PLA), polyhydroxybutyrate (PHB), P3HB4HB and PHBHHx. RaSMCs cultured on PU films had a quiescent contractile phenotype, indicating that they were fully functional. HaCat incubated on tailor-made PU films showed a proliferation approximately equal to tissue-culture plates (TCPs). Blood coagulation behavior tests revealed a strong platelet adhesion and a short coagulation time on PU films. This study demonstrated potential medical applications for P3HB4HB and PHBHHx based polyurethane as a hydrophobic wound-healing and hemostatic materials. PMID:19622282

  20. [FTIR study on the synthesis of poly(propylene fumarate) and its copolymer].

    PubMed

    Zhang, Na; Cai, Zhong-yu; Chang, Jun-biao

    2010-01-01

    Poly(propylene fumarate) (PPF) is one kind of linear biodegradable polyester and the unsaturated double bonds along its main chain can be crosslinked with other olefinic monomers to form three-dimensional networks, and the networks can support tissues. In the present paper, firstly, the intermediate oligomer-bis (2-hydroxypropyl) fumarate (PFP) was synthesized, and then the unsaturated linear polyester PPF was synthesized with the oligomer PFP through melting condensation process. Additionally, on the base of the process, the oligomer bis(2-hydroxypropyl) sebacate (PSP) was synthesized by similar method and then a kind of new copolymer named poly(propylene fumarate-co-propylene sebacate) [P(PF-co-PS)] that comprised bis(2-hydroxypropyl) sebacate segments was synthesized with PFP and PSP by melting condensation. During the synthesis process, the structures of bis(2-hdroxypropyl) fumarate, bis(2-hydroxypropyl) sebacate, PPF and P(PF-co-PS) were characterized by FTIR The results shows that with the polymerization going along, oligomer bis (2-hydroxypropyl) fumarate and bis(2-hydroxypropyl) sebacate converted to PPF or P(PF-co-PS) gradually. PMID:20302075

  1. Radiation synthesis of nanosilver nanohydrogels of poly(methacrylic acid)

    NASA Astrophysics Data System (ADS)

    Gupta, Bhuvanesh; Gautam, Deepti; Anjum, Sadiya; Saxena, Shalini; Kapil, Arti

    2013-11-01

    Nanosilver nanohydrogels (nSnH) of poly(methacrylic acid) were synthesized and stabilized using gamma irradiation. The main objective of this study was to develop silver nanoparticles and to evaluate the antimicrobial activity. Radiation helps in the polymerization, crosslinking and reduction of silver nitrate as well. Highly stable and uniformly distributed silver nanoparticles have been obtained within hydrogel network by water in oil nanoemulsion polymerization and were evaluated by dynamic light scattering (DLS) and transmission electron microscopy (TEM) respectively. TEM showed almost spherical and uniform distribution of silver nanoparticles through the hydrogel network. The mean size of silver nanoparticles ranging is 10-50 nm. The nanohydrogels showed good swelling in water. Antibacterial studies of nSnH suggest that it can be a good candidate as coating material in biomedical applications.

  2. Poly(vinylpyrrolidone) for bioconjugation and surface ligand immobilization.

    PubMed

    Zelikin, Alexander N; Such, Georgina K; Postma, Almar; Caruso, Frank

    2007-09-01

    Poly(vinylpyrrolidone) (PVP), a nonionic and nontoxic polymer with antifouling properties, has been synthesized via RAFT polymerization to obtain thiol-terminated PVP. We demonstrate that when the polymer is adsorbed onto the surface of colloidal silica particles, the terminal thiol groups of PVP remain accessible for chemical modification and lend themselves to the immobilization of ligands. We show that ligand attachment onto the surface via conjugation to PVP is reversible, as the polymer can be desorbed from the surface for conjugate and surface recovery. We present the conjugation of a model peptide and an oligonucleotide to PVP via the polymer terminal thiol and demonstrate that conjugates remain functional in molecular recognition assay. The developed technique offers a novel method to functionalize low-fouling surfaces for a variety of biomedical applications and presents opportunities to use PVP as a macromolecular drug carrier. PMID:17715962

  3. Poly(N-isopropylacrylamide) Phase Diagrams: Fifty Years of Research.

    PubMed

    Halperin, Avraham; Kröger, Martin; Winnik, Françoise M

    2015-12-14

    In 1968, Heskins and Guillet published the first systematic study of the phase diagram of poly(N-isopropylacrylamide) (PNIPAM), at the time a "young polymer" first synthesized in 1956. Since then, PNIPAM became the leading member of the growing families of thermoresponsive polymers and of stimuli-responsive, "smart" polymers in general. Its thermal response is unanimously attributed to its phase behavior. Yet, in spite of 50 years of research, a coherent quantitative picture remains elusive. In this Review we survey the reported phase diagrams, discuss the differences and comment on theoretical ideas regarding their possible origins. We aim to alert the PNIPAM community to open questions in this reputably mature domain. PMID:26612195

  4. Synthesis and Characterization of New Poly(silole-fluorene) Copolymers.

    PubMed

    Lee, Yun-Ji; Park, Jeong Cheol; Yun, Hui-Jun; Park, Jong-Man; Kim, Yun-Hi

    2015-02-01

    New poly(silole-fluorene) copolymers were designed and synthesized. Copolymers were obtained by Suzuki coupling reaction with different ratio of fluorene and silole. The obtained copolymers were characterized by the spectroscopic methods such as FT-IR and 1H-NMR spectroscopies. The resulting copolymers were soluble in common organic solvents such as toluene, tetrahydrofurane, chloroform, chlorobenzene, etc. The obtained copolymers showed thermal stabilities, which were characterized by TGA and DSC. PLEDs with device configurations of ITO/PEDOT:PSS/Copolymer I~VI/LiF/AI. The best device performances, with maximum brightness of 231.5 cd/m2 at a current density (J) of 408.3 mA/cm2, and a maximum luminance efficiency of 0.115 cd/A, were achieved in the composition of fluorene and silole moiety (0.9:0.1). PMID:26353724

  5. Crystallization and Solid State Structure of Poly(lactide) Copolymers

    NASA Astrophysics Data System (ADS)

    Baratian, S.; Runt, J.; Hall, E.; Lin, J. S.

    2000-03-01

    A series of random poly(lactide) copolymers was synthesized from L-lactide and D,L lactide using a tin (II) octanoate catalyst. The copolymers contained from 1.7 to 6.2 percent R stereochemical defects in otherwise S stereoisomer chains. Small-angle x-ray scattering experiments were used to determine the final lamellar microstructure of the copolymers. Lamellar thicknesses were strongly dependent on R co-unit concentration and it was concluded that the final structure contains significant pockets of non-crystalline material between spherulite fibrils. Equilibrium melting temperatures were estimated using the Gibbs-Thomson approach and their variation with comonomer content suggests that there is significant exclusion of R stereochemical defects from crystalline regions. Spherulite growth rates of the D-lactide copolymers were found to be larger than L-lactide/meso-lactide copolymers at equivalent optical composition.

  6. Poly(N-arylenbenzimidazoles) via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

    1995-01-01

    Novel poly(N-arylenebenzimidazole)s (PNABIs) are prepared by the aromatic nucleophilic displacement reaction of novel di(hydroxyphenyl-N-arylene benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl N-arylenebenzimidazole) monomers are synthesized by reacting phenyl 4-hydroxybenzoate with bis(2-aminoanilino) arylenes in diphenylsulfone. Moderate molecular weight PNABIs of new chemical structures were prepared that exhibit a favorable combination of physical and mechanical properties. The use of the novel di(hydroxyphenyl N-arylenebenzimidazole)s permits a more economical and easier way to prepare PNABIs than previous routes.

  7. Poly(N-arylenebenzimidazole)s via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Jr., Joseph G. (Inventor)

    1996-01-01

    Novel poly(N-arylenebenzimidazole)s (PNABls) are prepared by the aromatic nucleophilic displacement reaction of novel di(hydroxyphenyl-N-arylene benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl-N-arylenebenzimidazole) monomers are synthesized by reacting phenyl-4-hydroxybenzoate with bis(2-aminoanilino)arylenes in diphenylsulfone. Moderate molecular weight PNABIs of new chemical structures were prepared that exhibit a favorable combination of physical and mechanical properties. The use of the novel di(hydroxyphenyI-N-arylenebenzimidazole)s permits a more economical and easier way to prepare PNABIs than previous routes.

  8. Poly(ethylene oxide) functionalization

    DOEpatents

    Pratt, Russell Clayton

    2014-04-08

    A simple procedure is provided by which the hydroxyl termini of poly(ethylene oxide) can be appended with functional groups to a useful extent by reaction and precipitation. The polymer is dissolved in warmed toluene, treated with an excess of organic base and somewhat less of an excess of a reactive acylating reagent, reacted for several hours, then precipitated in isopropanol so that the product can be isolated as a solid, and salt byproducts are washed away. This procedure enables functionalization of the polymer while not requiring laborious purification steps such as solvent-solvent extraction or dialysis to remove undesirable side products.

  9. Novel symmetric amphiphilic dendritic poly(L-lysine)-b-poly(L-lactide)-b-dendritic poly(L-lysine) with high plasmid DNA binding affinity as a biodegradable gene carrier.

    PubMed

    Li, Yang; Cui, Liang; Li, Qiaobo; Jia, Lin; Xu, Yuhong; Fang, Qiang; Cao, Amin

    2007-05-01

    This study communicates the molecular design, preparation, and biological application of novel symmetric amphiphilic polycationic dendritic poly(L-lysine)-b-poly(L-lactide)-b-dendritic poly(L-lysine) D2-LLA15-D2 bearing two two-generation poly(L-lysine) PLL dendrons D2 and a central hydrophobic biodegradable poly(L-lactide) block LLA15. First, an amino-protected precursor of L1-OH was designed and synthesized and was further employed to prepare L1-LLA15 with an organic 4-(dimethylamino)-pyridine-mediated living-ring-opening polymerization of l-lactide. Subsequently, the hydroxy end-capped L1-LLA15 was coupled to synthesize a new triblock L1-LLA15-L1 with two one-generation amino-protected PLL dendrons L1. Furthermore, with a repeated trifluoroacetic-acid-mediated amino deprotection-protection cycle, new amphiphilic triblock D2-LLA15-D2 was successfully prepared. By means of NMR, mass spectrometry, and gel permeation chromatography, these synthetic precursors and final amphiphilic product were characterized to bear well-defined triblock structures. In addition, this synthesized amphiphilic triblock polycationic macromolecule was applied as a new polycationic plasmid DNA carrier, and its DNA binding affinity was examined via an agarose electrophoresis and a fluorescence titration assay along with two important references of hydrophilic dendritic D2-HEX-D2 and double-hydrophilic D2-PEG-4K-D2 bearing the same two D2 dendrons; much enhanced DNA binding affinity was interestingly revealed for the new amphiphilic structural D2-LLA15-D2. Moreover, the assembled polyplex microparticles of plasmid DNA/polycationic carrier were further analyzed by dynamic light scattering and transmission electron microscopy, indicating their averaged nanoparticle size around 150-200 nm. As for the cytotoxicity of the new D2-LLA15-D2, MTT assays were conducted with a human hepatocellular carcinoma cell line (SMMC-7721), indicating a very low cytotoxicity as compared with commercial linear PLL

  10. Metal silicide/poly-Si Schottky diodes for uncooled microbolometers

    PubMed Central

    2013-01-01

    Nickel silicide Schottky diodes formed on polycrystalline Si 〈P〉 films are proposed as temperature sensors of monolithic uncooled microbolometer infrared focal plane arrays. The structure and composition of nickel silicide/polycrystalline silicon films synthesized in a low-temperature process are examined by means of transmission electron microscopy. The Ni silicide is identified as a multi-phase compound composed of 20% to 40% of Ni3Si, 30% to 60% of Ni2Si, and 10% to 30% of NiSi with probable minor content of NiSi2 at the silicide/poly-Si interface. Rectification ratios of the Schottky diodes vary from about 100 to about 20 for the temperature increasing from 22℃ to 70℃; they exceed 1,000 at 80 K. A barrier of around 0.95 eV is found to control the photovoltage spectra at room temperature. A set of barriers is observed in photo-electromotive force spectra at 80 K and attributed to the Ni silicide/poly-Si interface. Absolute values of temperature coefficients of voltage and current are found to vary from 0.3%℃ to 0.6%/℃ for forward bias and around 2.5%/℃ for reverse bias of the diodes. PMID:23594606

  11. Poly(Limonene Thioether) Scaffold for Tissue Engineering.

    PubMed

    Fischer, Kristin M; Morgan, Kathy Ye; Hearon, Keith; Sklaviadis, Demetra; Tochka, Zachary L; Fenton, Owen S; Anderson, Daniel G; Langer, Robert; Freed, Lisa E

    2016-04-01

    A photocurable thiol-ene network polymer, poly(limonene thioether) (PLT32o), is synthesized, characterized, fabricated into tissue engineering scaffolds, and demonstrated in vitro and in vivo. Micromolded PLT32o grids exhibit compliant, elastomeric mechanical behavior similar to grids made of poly(glycerol sebacate) (PGS), an established biomaterial. Multilayered PL32o scaffolds with regular, geometrically defined pore architectures support heart cell seeding and culture in a manner similar to multilayered PGS scaffolds. Subcutaneous implantation of multilayered PLT32o scaffolds with cultured heart cells provides long-term 3D structural support and retains the exogenous cells, whereas PGS scaffolds lose both their structural integrity and the exogenous cells over 31 d in vivo. PLT32o membrane implants retain their dry mass, whereas PGS implants lose 70 percent of their dry mass by day 31. Macrophages are initially recruited to PLT32o and PGS membrane implants but are no longer present by day 31. Facile synthesis and processing in combination with the capability to support heart cells in vitro and in vivo suggest that PLT32o can offer advantages for tissue engineering applications where prolonged in vivo maintenance of 3D structural integrity and elastomeric mechanical behavior are required. PMID:26890480

  12. Rheological kinetics of thermo-sensitive supramolecular assemblies from poly( N-isopropyl acrylamide) and adenine-functionalized poly(ethylene oxide) stabilized by complementary multiple hydrogen bonds

    NASA Astrophysics Data System (ADS)

    Cui, Hui-Wang; Kuo, Shiao-Wei

    2014-05-01

    In this study, we synthesized a poly( N-isopropylacrylamide) (PNIPAm) through the polymerization of N-isopropylacrylamide in distilled water with azodiisobutyronitrile as the initiator and a bisadenine-functionalized poly(ethylene oxide) (A-PEO-A) from the reaction of adenine with a difunctionalized toluenesulfonyl-PEO. When blended together in distilled water, PNIPAm and A-PEO-A formed supramolecular aggregates stabilized through complementary multiple hydrogen bonds between the amide groups of PNIPAm and the adenine units of A-PEO-A. Agrawal integral equation and rheometry revealed the rheological kinetics of supramolecular assemblies, which were influenced significantly by the spherical micelles, large associated aggregates of spherical micelles, network structures, and toroid structures formed in aqueous solutions.

  13. Oxidation effects of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) electrodes on high-performance organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Jang, Yunseok; Jo, Jeongdai; Choi, Young-Man; Woo, Kyoohee; Kwon, Sin; Kim, Kwang-Young

    2015-06-01

    We adjusted the conductivity of a poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT/PSS) electrode and an injection barrier between the PEDOT/PSS source/drain (S/D) electrode and a pentacene semiconductor by adding HAuCl4 to a PEDOT/PSS solution. Gold in the PEDOT/PSS S/D electrode was synthesized by a redox reaction between PEDOT/PSS and Au ions. This reaction enhances the conductivity of the PEDOT/PSS S/D electrodes and reduces the injection barrier between the PEDOT/PSS S/D electrodes and the pentacene semiconductor, and causes the field-effect mobility to increase by about 230%. As such, it is considered a very useful method of making high-performance organic thin-film transistors (OTFTs).

  14. Studies on biodegradable and crosslinkable poly(castor oil fumarate)/poly(propylene fumarate) composite adhesive as a potential injectable biomaterial.

    PubMed

    Mitha, M K; Jayabalan, M

    2009-12-01

    Biodegradable hydroxyl terminated-poly(castor oil fumarate) (HT-PCF) and poly(propylene fumarate) (HT-PPF) resins were synthesized as an injectable and in situ-cross linkable polyester resins for orthopedic applications. An injectable adhesive formulation containing this resin blend, N-vinyl pyrrolidone (NVP), hydroxy apatite, free radical initiator and accelerator was developed. The Composite adhesives containing the ratio of resin blend and NVP, 2.1:1.5, 2.1:1.2 and 2.1:1.0 set fast with tolerable exothermic temperature as a three dimensionally cross linked toughened material. Crosslink density and mechanical properties of the crosslinked composite increase with increase of NVP. The present crosslinked composite has hydrophilic character and cytocompatibility with L929 fibroblast cells. PMID:18592346

  15. Poly(DL-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate): synthesis, characterization, micellization behavior in aqueous solutions, and encapsulation of the hydrophobic drug dipyridamole.

    PubMed

    Karanikolopoulos, Nikos; Zamurovic, Miljana; Pitsikalis, Marinos; Hadjichristidis, Nikos

    2010-02-01

    We synthesized a series of well-defined poly(dl-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PDLLA-b-PDMAEMA) amphiphilic diblock copolymers by employing a three-step procedure: (a) ring-opening polymerization (ROP) of dl-lactide using n-decanol and stannous octoate, Sn(Oct)(2), as the initiating system, (b) reaction of the PDLLA hydroxyl end groups with bromoisobutyryl bromide, and (c) atom transfer radical polymerization, ATRP, of DMAEMA with the newly created bromoisobutyryl initiating site. The aggregation behavior of the prepared block copolymers was investigated by dynamic light scattering and zeta potential measurements at 25 degrees C in aqueous solutions of different pH values. The hydrophobic drug dipyridamole was efficiently incorporated into the copolymer aggregates in aqueous solutions of pH 7.40. High partition coefficient values were determined by fluorescence spectroscopy. PMID:20041661

  16. (m.n)-Homorubins. Syntheses and Structures

    PubMed Central

    Pfeiffer, William P.

    2014-01-01

    Five new homorubin analogs of bilirubin with their two dipyrrinone components conjoined to (CH2)2, (CH2)3, and (CH2)4 units were synthesized with propionic acid chains shortened to acetic and elongated to butyric, and examined by spectroscopy and molecular mechanics computations for an ability to form conformation-determining hydrogen bonds. With m designating the number of conjoining CH2 units and n indicating the number of CH2 units of the alkanoic acid chains of (m.n)-homorubins, (2.1), (3.2), (4.2), and (4.3) homorubins were prepared and compared with previously synthesized (2.2) and (2.3), which adopt intramolecularly hydrogen bonded conformations in CHCl3. PMID:25544780

  17. Syntheses and studies of organosilicon compounds

    SciTech Connect

    Xie, R.

    1999-02-12

    The syntheses of polycarbosilanes and polysilanes as silicon carbide ceramic precursors have been active research areas in the Barton Research Group. In this thesis, the work is focused on the preparation of polycarbosilanes and polysilanes as stoichiometric silicon carbide precursor polymers. The syntheses of the precursor polymers are discussed and the conversions of these precursors to silicon carbide via pyrolysis are reported. The XRD pattern and elemental analyses of the resulting silicon carbide ceramics are presented. Silicon monoxide is an important intermediate in the production of silicon metal. The existence of silicon monoxide in gap phase has been widely accepted. In the second part of this thesis, the generation of gaseous silicon monoxide in four different reactors and the reactions of gaseous silicon monoxide towards organic compounds are discussed.

  18. Gene Assembly from Chip-Synthesized Oligonucleotides

    PubMed Central

    Eroshenko, Nikolai; Kosuri, Sriram; Marblestone, Adam H; Conway, Nicholas; Church, George M.

    2012-01-01

    De novo synthesis of long double-stranded DNA constructs has a myriad of applications in biology and biological engineering. However, its widespread adoption has been hindered by high costs. Cost can be significantly reduced by using oligonucleotides synthesized on high-density DNA chips. However, most methods for using off-chip DNA for gene synthesis have failed to scale due to the high error rates, low yields, and high chemical complexity of the chip-synthesized oligonucleotides. We have recently demonstrated that some commercial DNA chip manufacturers have improved error rates, and that the issues of chemical complexity and low yields can be solved by using barcoded primers to accurately and efficiently amplify subpools of oligonucleotides. This article includes protocols for computationally designing the DNA chip, amplifying the oligonucleotide subpools, and assembling 500-800 basepair (bp) constructs. PMID:25077042

  19. The microprocessor-based synthesizer controller

    NASA Technical Reports Server (NTRS)

    Wick, M. R.

    1980-01-01

    Implementation and performance of the microprocessor-based controllers and Dana Digiphase Synthesizer (DCO) installed in the Deep Space Network exciter in the 64-meter and 34-meter subnets to support uplink tuning required for the Voyager-Saturn Encounter is discussed. Test data in tests conducted during the production of the controllers verified the design objective for phase control accuracy of 10 to the - 12 power cycles in eight hours during ramping. Tests conducted require a phase error between a theoretical calculated value and the actual phase of no greater than + or - 1 cycle. Tests included (1) a ramp over a period of eight hours using a ramp rate which covers the synthesizer tuning range (40-51 MHz) and (2) a ramp sequence using the maximum rate (+ or kHz/s) over the tuning range.

  20. Genome Mining for Ribosomally Synthesized Natural Products

    PubMed Central

    Velásquez, Juan E.; van der Donk, Wilfred

    2011-01-01

    In recent years, the number of known peptide natural products that are synthesized via the ribosomal pathway has rapidly grown. Taking advantage of sequence homology among genes encoding precursor peptides or biosynthetic proteins, in silico mining of genomes combined with molecular biology approaches has guided the discovery of a large number of new ribosomal natural products, including lantipeptides, cyanobactins, linear thiazole/oxazole-containing peptides, microviridins, lasso peptides, amatoxins, cyclotides, and conopeptides. In this review, we describe the strategies used for the identification of these ribosomally-synthesized and posttranslationally modified peptides (RiPPs) and the structures of newly identified compounds. The increasing number of chemical entities and their remarkable structural and functional diversity may lead to novel pharmaceutical applications. PMID:21095156

  1. Nanocrystalline diamond synthesized from C60

    SciTech Connect

    Dubrovinskaia, N.; Dubrovinsky, L.; Langehorst, F.; Jacobsen, S.; Liebske, C.

    2010-11-30

    A bulk sample of nanocrystalline cubic diamond with crystallite sizes of 5-12 nm was synthesized from fullerene C{sub 60} at 20(1) GPa and 2000 C using a multi-anvil apparatus. The new material is at least as hard as single crystal diamond. It was found that nanocrystalline diamond at high temperature and ambient pressure kinetically is more stable with respect to graphitization than usual diamonds.

  2. Method of synthesizing a low density material

    DOEpatents

    Lorensen, L.E.; Monaco, S.B.

    1987-02-27

    A novel method of synthesizing a polymeric material of low density of the order of 50mg/cc or less. Such a low density material has applications in many areas including laser target fabrication. The method comprises preparing a polymer blend of two incompatible polymers as a major and a minor phase by mixing them and extruding the mixture, and then selectively extracting the major component, to yield a fine, low density structure.

  3. Method for synthesizing ultrafine powder materials

    DOEpatents

    Buss, Richard J.; Ho, Pauline

    1988-01-01

    A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400.degree. K. (127.degree.C.). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material.

  4. A MALDI-TOF MS study of oligomeric poly(m-phenyleneisophthalamide).

    PubMed

    Gies, Anthony P; Nonidez, William K; Ellison, Sparkle T; Ji, Haining; Mays, Jimmy W

    2005-02-01

    MALDI-TOF MS was used to study the end-group distribution of a series of poly(m-phenyleneisophthalamide) oligomers which were synthesized using various mole percent ratios of diamine to diacid chloride (90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, and 10:90) to clarify results obtained in previous work published in this journal. Oligomers synthesized with excess diamine or excess diacid chloride were found to contain abundances of amine or carboxylate end groups, respectively, as expected. Oligomers synthesized with equal molar ratios of reactants produced cyclic species which were also found in a previous publication as an oligomer in commercially produced, high molecular mass Nomex. PMID:15679344

  5. Shock Syntheses of Novel Nitrides and Biomolecules

    NASA Astrophysics Data System (ADS)

    Sekine, Toshimori

    2013-06-01

    High-pressure spinel nitride of Si3N4 was discovered more than 10 years ago. Since then there have been many studies on the spinel nitrides and related materials including oxynitrides. We have developed shock synthesis method to investigate their structural, mechanical, chemical, physical, and optical properties. At the same time we tried to synthesize carbon nitrides from the organic substances. And later we extended to shock synthesis of ammonia through the Haber-Bosch reaction under shock in order to apply geochemical subjects related to the origin of life. The simplest amino acid of glycine, as well as animes (up to propylamine) and carboxylic acids (up to pentanoic acid), has been synthesized successfully in aqueous solutions through meteoritic impact reactions. Recently we are trying to make more complex biomolecules for implications of biomolecule formation for the origin of life through meteorite impacts on early Earth's ocean. These results of shock syntheses may imply significant contributions to materials science and Earth and planetary sciences. This research is collaborated with National Institute for Materials Science and Tohoku University.

  6. Wax ester-synthesizing activity of lipases.

    PubMed

    Tsujita, T; Sumiyoshi, M; Okuda, H

    1999-11-01

    The synthesis/hydrolysis of wax esters was studied in an aqueous solution using purified rat pancreatic lipase, porcine pancreatic carboxylester lipase, and Pseudomonas fluorescens lipase. The equilibrium between wax ester synthesis and hydrolysis favored ester formation at neutral pH. The synthesizing activities were measured using free fatty acid or triacylglycerol as the acyl donor and an equimolar amount of long-chain alcohol as the acyl acceptor. When oleic acid and hexadecanol emulsified with gum arabic were incubated with these lipases, wax ester was synthesized, in a dose- and time-dependent manner, and the apparent equilibrium ratio of palmityl oleate/free oleic acid was about 0.9/0.1. These lipases catalyzed the hydrolysis of palmityl oleate emulsified with gum arabic, and the apparent equilibrium ratio of palmityl oleate/free oleic acid was also about 0.9/0.1. The apparent equilibrium ratio of wax ester/free fatty acid catalyzed by lipase depended on incubation pH and fatty alcohol chain length. When equimolar amounts of trioleoylglycerol and fatty acyl alcohol were incubated with pancreatic lipase, carboxylester lipase, or P. fluorescens lipase, wax esters were synthesized dose-dependently. These results suggest that lipases can catalyze the synthesis of wax esters from free fatty acids or through degradation of triacylglycerol in an aqueous medium. PMID:10606038

  7. Method of synthesizing cubic system boron nitride

    SciTech Connect

    Yuzu, S.; Sumiya, H.; Degawa, J.

    1987-10-13

    A method is described for synthetically growing cubic system boron nitride crystals by using boron nitride sources, solvents for dissolving the boron nitride sources, and seed crystals under conditions of ultra-high pressure and high temperature for maintaining the cubic system boron nitride stable. The method comprises the following steps: preparing a synthesizing vessel having at least two chambers, arrayed in order in the synthesizing vessel so as to be heated according to a temperature gradient; placing the solvents having different eutectic temperatures in each chamber with respect to the boron nitride sources according to the temperature gradient; placing the boron nitride source in contact with a portion of each of the solvents heated at a relatively higher temperature and placing at least a seed crystal in a portion of each of the solvents heated at a relatively lower temperature; and growing at least one cubic system boron nitride crystal in each of the solvents in the chambers by heating the synthesizing vessel for establishing the temperature gradient while maintaining conditions of ultra-high pressure and high temperature.

  8. Sub-5 nm Domains in Ordered Poly(cyclohexylethylene)-block-poly(methyl methacrylate) Block Polymers for Lithography.

    SciTech Connect

    Kennemur, Justin; Yao, Li; Bates, Frank Stephen; Hillmyer, Marc

    2014-01-01

    A series of poly(cyclohexylethylene)-block-poly- (methyl methacrylate) (PCHE PMMA) diblock copolymers with varying molar mass (4.9 kg/mol Mn 30.6 kg/mol) and narrow molar mass distribution were synthesized through a combination of anionic and atom transfer radical polymerization (ATRP) techniques. Heterogeneous catalytic hydrogenation of -(hydroxy)polystyrene (PS-OH) yielded -(hydroxy)poly(cyclohexylethylene) (PCHEOH) with little loss of hydroxyl functionality. PCHE-OH was reacted with -bromoisobutyryl bromide (BiBB) to produce an ATRP macroinitiator used for the polymerization of methyl methacrylate. PCHE PMMA is a glassy, thermally stable material with a large effective segment segment interaction parameter, eff = (144.4 6.2)/T (0.162 0.013), determined by meanfield analysis of order-to-disorder transition temperatures (TODT) measured by dynamic mechanical analysis and differential scanning calorimetry. Ordered lamellar domain pitches (9 D 33 nm) were identified by small-angle X-ray scattering from neat BCPs containing 43 52 vol % PCHE ( f PCHE). Atomic force microscopy was used to show 7.5 nm lamellar features (D = 14.8 nm) which are some of the smallest observed to date. The lowest molar mass sample (Mn = 4.9 kg/mol, f PCHE = 0.46) is characterized by TODT = 173 3 C and sub-5 nm nanodomains, which together with the sacrificial properties of PMMA and the high overall thermal stability place this material at the forefront of high- systems for advanced nanopatterning applications.

  9. Protein release from water-swellable poly(D,L-lactide-PEG)-b-poly(ϵ-caprolactone) implants.

    PubMed

    Stanković, Milica; Hiemstra, Christine; de Waard, Hans; Zuidema, Johan; Steendam, Rob; Frijlink, Henderik W; Hinrichs, Wouter L J

    2015-03-01

    In this study, water-swellable multiblock copolymers composed of semi-crystalline poly(ϵ-caprolactone) [PCL] blocks and amorphous blocks consisting of poly(D,L-lactide) (PDLLA) and poly(ethylene glycol) (PEG) [PDLLA-PEG] were synthesized. The block ratio of these [PDLLA-PEG]-b-[PCL] multiblock copolymers was varied and the degradation of implants prepared of these polymers by hot melt extrusion (HME) was compared with implants prepared of [PCL-PEG]-b-[PCL], a copolymer which has been described previously (Stanković et al., 2014). It was shown that the initial degradation rate of the [PDLLA-PEG]-b-[PCL] multiblock copolymers increased with increasing the content of amorphous [PDLLA-PEG] block and that the degradation rate of these multiblock copolymers was faster than that of the [PCL-PEG]-b-[PCL] multiblock copolymers due to rapid degradation of the [PDLLA-PEG] block. Furthermore, the release of the model proteins lysozyme and bovine serum albumin from polymer implants prepared by HME was studied. It was found that the protein release from [PDLLA-PEG]-b-[PCL] copolymers was incomplete, which is not acceptable for any application of these polymers. Besides, [PCL-PEG]-b-[PCL] copolymers showed slow and continuous release. We hypothesize that the incomplete release is explained by an irreversible interaction between the proteins and polymer degradation products or by entrapment of the protein in the hydrophobic and non-swellable polymer matrix that was left after degradation and loss of the hydrophilic [PDLLA-PEG] blocks from the degrading polymer. PMID:25575472

  10. Localization properties of electronic states in a polaron model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers.

    PubMed

    Yamada, H; Starikov, E B; Hennig, D; Archilla, J F R

    2005-06-01

    We numerically investigate localization properties of electronic states in a static model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers with realistic parameters obtained by quantum-chemical calculation. The randomness in the on-site energies caused by the electron-phonon coupling is completely correlated to the off-diagonal parts. In the single electron model, the effect of the hydrogen-bond stretchings, the twist angles between the base pairs and the finite system size effects on the energy dependence of the localization length and on the Lyapunov exponent are given. The localization length is reduced by the influence of the fluctuations in the hydrogen bond stretchings. It is also shown that the helical twist angle affects the localization length in the poly(dG)-poly(dC) DNA polymer more strongly than in the poly(dA)-poly(dT) one. Furthermore, we show resonance structures in the energy dependence of the localization length when the system size is relatively small. PMID:15906117

  11. Electrochemical properties of electrospun poly(5-cyanoindole) submicron-fibrous electrode for zinc/polymer secondary battery

    NASA Astrophysics Data System (ADS)

    Cai, Zhijiang; Guo, Jie; Yang, Haizheng; Xu, Yi

    2015-04-01

    This study aims to develop an aqueous zinc/electrospun poly(5-cyanoindole) fibers secondary battery system. Zn foil and ZnCl2 are used as anode active materials and the electrolytic solution, respectively. Poly(5-cyanoindole) synthesized by chemical oxidation is electrospun into fibers and used as cathode active materials. FTIR and NMR test are carried out to investigate the chemical structure of poly(5-cyanoindole). Surface properties of electrospun poly(5-cyanoindole) fibers are studied by SEM, TEM, and BET. The performance of zinc/electrospun poly(5-cyanoindole) fibers battery system is evaluated in term of electrical conductivity, cyclic voltammogram, electrochemical impedance spectroscopy, discharge capacity and durability test. The cell achieves 2.0 V electromotive force with about 107-61 Ah Kg-1 discharge capacity at 0.2C-10C rate. At 800th cycle, the discharge capacity remains 80-57 Ah Kg-1 at 0.2C-2C rate, which is about 75-63% of the maximum discharge capacity. These results indicate that the cell has very excellent cyclic properties as well as fast charge/discharge properties. Electrospun poly(5-cyanoindole) fibers have been proved to be a better candidate than polyindole powder as cathode material in zinc/polymer battery.

  12. Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate).

    PubMed

    Kim, Hyun Yul; Ryu, Je Ho; Chu, Chong Woo; Son, Gyung Mo; Jeong, Young-Il; Kwak, Tae-Won; Kim, Do Hyung; Chung, Chung-Wook; Rhee, Young Ha; Kang, Dae Hwan; Kim, Hyung Wook

    2014-01-01

    Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a (1)H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes and their particle sizes were less than 100 nm. In a (1)H-NMR study in D2O, specific peaks of PEG solely appeared while peaks of PHO disappeared, indicating that nanoparticles have core-shell structures. The higher M.W. of PEG decreased loading efficiency and particle size. The higher drug feeding increased drug contents and average size of nanoparticles. In the drug release study, the higher M.W. of PEG block induced the acceleration of drug release rate. The increase in drug contents induced the slow release rate of drug. In an antitumor activity study in vitro, paclitaxel nanoparticles have practically similar anti-proliferation activity against HCT116 human colon carcinoma cells. In an in vivo animal study using HCT116 colon carcinoma cell-bearing mice, paclitaxel nanoparticles have enhanced antitumor activity compared to paclitaxel itself. Therefore, paclitaxel-incorporated nanoparticles of PHO/PEG block copolymer are a promising vehicle for antitumor drug delivery. PMID:25288916

  13. New Poly(dimethylsiloxane)/Poly(perfluorooctylethyl acrylate) Block Copolymers: Structure and Order Across Multiple Length Scales in Thin Films

    SciTech Connect

    E Martinelli; G Galli; S Krishnan; M Paik; C Ober; D Fischer

    2011-12-31

    Three sets of a new class of low surface tension block copolymers were synthesized consisting of a poly(dimethylsiloxane) (PDMS) block and a poly(perfluorooctylethyl acrylate) (AF8) block. The polymers were prepared using a bromo-terminated PDMS macroinitiator, to which was attached an AF8 block grown using atom transfer radical polymerization (ATRP) in such a designed way that the molecular weight and composition of the two polymer blocks were regularly varied. The interplay of both the phase separated microstructure and the mesomorphic character of the fluorinated domains with their effect on surface structure was evaluated using a suite of analytical tools. Surfaces of spin-coated and thermally annealed films were assessed using a combination of X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) studies. Both atomic force microscopy (AFM) measurements and grazing incidence small angle X-ray scattering (GISAXS) studies were carried out to evaluate the microstructure of the thin films. Even in block copolymers in which the PDMS block was the majority component, a significant presence of the lower surface energy AF8 block was detected at the film surface. Moreover, the perfluorooctyl helices of the AF8 repeat units were highly oriented at the surface in an ordered, tilted smectic structure, which was compared with those of the bulk powder samples using wide-angle X-ray powder diffraction (WAXD) studies.

  14. Lyotropic Phase Behavior of Poly(ethylene oxide)-Poly(butadiene) Diblock Copolymers: Evolution of the Random Network Morphology

    SciTech Connect

    Jain, Sumeet; Dyrdahl, Mitchell H.E.; Gong, Xiaobo; Scriven, L.E.; Bates, Frank S.

    2008-10-24

    The phase behavior of poly(ethylene oxide)-poly(butadiene) (PEO-PB) diblock copolymers mixed with water was studied using small-angle X-ray scattering (SAXS), cryogenic scanning electron microscopy (cryo-SEM), cryogenic transmission electron microscopy (cryo-TEM), and dynamic mechanical spectroscopy. Two sets of diblocks were synthesized by adding different lengths of PEO to hydroxy terminated PB with degrees of polymerization N{sub PB} = 46 and 170. Two-component mixtures were investigated as a function of block composition and copolymer molecular weight, between 1 and 100 wt % polymer content. Melt phase behavior is consistent with established theory and known experimental behavior for diblock copolymers. Various lyotropic liquid crystalline structures, notably lamellae (L), hexagonally packed cylinders (H), and spheres (S) arranged on cubic (body-centered cubic, face-centered cubic) lattices, were documented as a function of water content. At the higher molecular weights (N{sub PB} = 170), a random network phase (N) was identified over a sizable portion of the phase portrait, located between hexagonally ordered cylinders and ordered lamellae. This new structure, along with branching of cylindrical micelles in the dilute limit, bear a striking similarity to experimentally observed and theoretically predicted phase behavior in certain ternary water/oil/surfactant systems. These findings demonstrate that block copolymer surfactants are characterized by at least four structural building blocks -- spheres, cylinders, bilayers, and branched cylinders -- above a threshold molecular weight.

  15. Enzymatic synthesis of poly-L-lactide and poly-L-lactide-co-glycolide in an ionic liquid.

    PubMed

    Chanfreau, Sébastien; Mena, Maria; Porras-Domínguez, Jaime R; Ramírez-Gilly, Mariana; Gimeno, Miquel; Roquero, Pedro; Tecante, Alberto; Bárzana, Eduardo

    2010-06-01

    The syntheses of poly-L-lactide (PLLA) and poly-L-lactide-co-glycolide (PLLGA) is reported in the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM][PF(6)] mediated by the enzyme lipase B from Candida antarctica (Novozyme 435). The highest PLLA yield (63%) was attained at 90 degrees C with a molecular weight (M(n)) of 37.8 x 10(3) g/mol determined by size exclusion chromatography. This procedure produced relatively high crystalline polymers (up to 85% PLLA) as determined by DSC. In experiments at 90 degrees C product synthesis also occurred without biocatalyst, however, PLLA synthesis in [HMIM][PF(6)] at 65 degrees C followed only the enzymatic mechanism as ring opening was not observed without the enzyme. In addition, the enzymatic synthesis of PLLGA is first reported here using Novozyme 435 biocatalyst with up to 19% of lactyl units in the resulting copolymer as determined by NMR. Materials were also characterized by TGA, MALDI-TOF-MS, X-ray diffraction, polarimetry and rheology. PMID:19888606

  16. Controlled release of paclitaxel from biodegradable unsaturated poly(ester amide)s/poly(ethylene glycol) diacrylate hydrogels.

    PubMed

    Guo, Kai; Chu, C C

    2007-01-01

    Biodegradable hydrogels (FPBe-G) were synthesized by the photopolymerization of two precursors: FPBe, a fumurate-based unsaturated poly(ester amide) (UPEA), and poly(ethylene glycol) diacrylate (PEG-DA). Depending on the feed ratio of these two precursors, the resultant FPBe-G hydrogels showed different crosslinking levels of network structure, mesh sizes (xi) and matrix morphology. When a lipophilic drug, paclitaxel, was preloaded into FPBe-G hydrogels, the two-month drug-release kinetics from FPBe-G hydrogels in both pure PBS buffer and alpha-chymotrypsin media were measured. The paclitaxel-preloaded FPBe-G hydrogels in a alpha-chymotrypsin solution had significantly faster drug release rate than the corresponding hydrogels in a pure PBS buffer due to an enzyme catalyzed biodegradation of FPBe-G hydrogels. Sustained paclitaxel releases over a two-month period without initial burst release were also achieved by using hydrogels having certain feed ratios of hydrogel precursors. These paclitaxel release data correlated well with the molecular mesh size (xi), molecular weight between cross-links (M(c)) and matrix morphological structure of FPBe-G hydrogels. PMID:17550654

  17. Alternative block polyurethanes based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) and poly(ethylene glycol).

    PubMed

    Pan, Jueyu; Li, Guangyao; Chen, Zhifei; Chen, Xianyu; Zhu, Wenfu; Xu, Kaitian

    2009-06-01

    A series of amphiphilic alternative block polyurethane copolymers based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) and poly(ethylene glycol) (PEG) were synthesized by a coupling reaction between P3/4HB-diol and PEG-diisocyanate, with different 3HB, 4HB, PEG compositions and segment lengths. Stannous octanoate was used as catalyst. The chemical structure, alternative block arrangement, molecular weight and distribution were systematically characterized by FTIR, (1)H NMR, GPC and composition analysis. The thermal property was studied by DSC and TGA. Platelet adhesion study revealed that the alternative block polyurethanes possess excellent hemocompatibility. CCK-8 assay illuminated that the non-toxic block polyurethanes maintain rat aortic smooth muscle cells (RaSMCs) good viability. The in-vitro degradation of the copolymers in PBS buffer solution and in lipase buffer medium was investigated. Results showed that the copolymer films exhibit different degradation patterns in different media from surface erosion to diffusion bulk collapsing. The synthetic methodology for the alternative block polyurethanes provides a way to control the exact structure of the biomaterials and tailor the properties to subtle requirements. PMID:19230967

  18. Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate)

    PubMed Central

    2014-01-01

    Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a 1H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes and their particle sizes were less than 100 nm. In a 1H-NMR study in D2O, specific peaks of PEG solely appeared while peaks of PHO disappeared, indicating that nanoparticles have core-shell structures. The higher M.W. of PEG decreased loading efficiency and particle size. The higher drug feeding increased drug contents and average size of nanoparticles. In the drug release study, the higher M.W. of PEG block induced the acceleration of drug release rate. The increase in drug contents induced the slow release rate of drug. In an antitumor activity study in vitro, paclitaxel nanoparticles have practically similar anti-proliferation activity against HCT116 human colon carcinoma cells. In an in vivo animal study using HCT116 colon carcinoma cell-bearing mice, paclitaxel nanoparticles have enhanced antitumor activity compared to paclitaxel itself. Therefore, paclitaxel-incorporated nanoparticles of PHO/PEG block copolymer are a promising vehicle for antitumor drug delivery. PMID:25288916

  19. Biodegradation of poly(tetramethylene succinate-co-tetramethylene adipate) and poly(tetramethylene succinate) through water-soluble products.

    PubMed

    Kitakuni, E; Yoshikawa, K; Nakano, K; Sasuga, J; Nobiki, M; Naoi, H; Yokota, Y; Ishioka, R; Yakabe, Y

    2001-05-01

    Poly(tetramethylene succinate-co-tetramethylene adipate) (PBSA) and poly(tetramethylenesuccinate) (PBS) were hydrolyzed experimentally into water-soluble oligomers and monomers by Chromobacterium extracellular lipase. The oligomers were identified by high-performance liquid chromatography-mass spectrometry and 1H-nuclear magnetic resonance, which indicated that a total of 28 oligomer species were liberated from PBSA, and that 13 of them were identical to the hydrolysates from PBS. Moreover, 20 of the species were polyester-based compounds of monomer units, and the other 8 species were small amounts of diurethane compounds. Bis(hydroxybutyl) succinate (BSB) and bis(hydroxybutyl) hexamethylene dicarbamate (BHB) were the typical oligomers and were chemically synthesized. Biodegradability of BSB and BHB was examined for 28 d in the activated sludge, and analysis of the results of this study indicated that the final conversion rate of constituent carbon to carbon dioxide was estimated at 80 mol% for BSB and 10 mol% for BHB. The remaining amount of carbon in the undegraded BHB was 20 mol%. In the presence of BSB, the biodegradability of BHB was increased by about 1.5 times. The suggestion was made that BSB induced a growth of microorganisms and helped BHB degradation. This is consistent with the observation that the biodegradation of BHB in native soil for 60 d reached > 60%. PMID:11337881

  20. A thermosensitive hydrogel based on biodegradable amphiphilic poly(ethylene glycol) polycaprolactone poly(ethylene glycol) block copolymers

    NASA Astrophysics Data System (ADS)

    Gong, Chang Yang; Qian, Zhi Yong; Liu, Cai Bing; Juan Huang, Mei; Gu, Ying Chun; Wen, Yan Jun; Kan, Bing; Wang, Ke; Dai, Mei; Li, Xing Yi; Gou, Ma Ling; Tu, Ming Jing; Wei, Yu Quan

    2007-06-01

    A series of low molecular weight poly(ethylene glycol)-polycaprolactone-poly(ethylene glycol) (PEG-PCL-PEG) biodegradable block copolymers were successfully synthesized using isophorone diisocyanate (IPDI) as the coupling agent, and were characterized using 1H NMR and Fourier transform infrared spectroscopy. The aqueous solutions of the PEG-PCL-PEG copolymers displayed a special thermosensitive gel-sol transition when the concentration was above the corresponding critical gel concentration. Gel-sol phase diagrams were recorded using the test-tube-inversion method; they depended on the hydrophilic/hydrophobic balance in the macromolecular structure, as well as some other factors, including the heating history, volume, and the ageing time of the copolymer aqueous solutions and dissolution temperature of the copolymers. As a result, the gel-sol transition temperature range could be altered, which might be very useful for application in injectable drug delivery systems. This work was financially supported by the Chinese Key Basic Research Program (2004CB518800 and 2004CB518807), and the Sichuan Key Project of Science and Technology (06(05SG022-021-02)).

  1. Constructing polyamidoamine dendrons from poly(poly(ethylene glycol) monomethacrylate) brushes grafted from planar silicon hydride surfaces for biomedical applications

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Zheng, Hong-Ning; Yan, Qin; Wang, Cuie; Ma, Yin-Zhou; Tang, Yan-Chun; Xiao, Shou-Jun

    2011-06-01

    A facile approach was established to construct polyamidoamine (PAMAM) dendrons from polymer brushes of poly(poly(ethylene glycol) monomethacrylate) (Si-g-P(PEGMA-OH)) grafted from a planar silicon hydride surface. First the Si-g-P(PEGMA-OH) brushes were grown via surface-initiated atom transfer radical polymerization with robust Si-C links on silicon surfaces. The side-chain hydroxyl groups of Si-g-P(PEGMA-OH) were chlorinated with thionyl chloride and further chlorines were substituted with amino groups of ethylenediamine, giving terminal primary amines. Borrowing the solution synthesis approach, we constructed second and third generations of PAMAM dendrons on-chip by surface-initiated alternative growth of two monomers, methyl acrylate and ethylenediamine. Two applications of silicon-based PAMAM dendrons were shown: the dense amino groups were activated via a cross-linker, N-succinimidyl-6-maleimidylhexanoate, to capture a free-thiol-carrying peptide of oxytocin and the third generation of PAMAM dendrons was used as a platform to on-chip synthesize a three amino acid peptide of Arg-Gly-Asp (RGD). The above conclusions were mainly derived from a home-built multiple transmission-reflection infrared spectroscopy, and complemented by X-ray photoelectron spectroscopy, UV-Vis spectroscopy and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry.

  2. Actuator based on sulfonated comb copolymer of poly (ethylene-co-vinyl alcohol) grafted by poly (ethylene glycol)

    NASA Astrophysics Data System (ADS)

    Gong, Guifen; Li, Lei; Zhang, Yujun

    2007-07-01

    Comb copolymer consisting of poly (ethylene-co-vinyl alcohol) (EVAL) as backbone and poly (ethylene glycol) (PEG) as side chains (EVAL-g-PEG) has been synthesized, then it was sulfonated by 1,3-propane sultone to get the final ionomer (EVAL-g-SPEG), and ionic polymer-metal composite (IPMC) based on EVAL-g-SPEG was prepared through electroless deposition of platinum onto the surfaces of EVAL-g-SPEG membrane. The graft copolymers were characterized with respect to molecular weight using gel permeation chromatography (GPC) and composition using 1H-NMR. The results showed that the No. of PEG graft of the side chains is n=1, 2 and others. Thermal properties were examined by DSC and TG. The melt temperature (T m) and glass transition temperature (T g) of the comb copolymer increase with the increasing length and the number of the side chains. Moreover, the deformation performance of IPMC material was tested and its results show that the starting response voltage of IPMC actuator decreases with the increasing IEC value. On the other hand, the starting response voltage increases with the decreased side chain length. The IPMC with n=2 side chain length of PEG has the maximum tip displacement, and the maximum tip displacement of IPMC membrane generally decreases with the side chain length of EVAL-g-SPEG. This feature may be the reflection of two opposite effects, namely the decreasing ion densities and increasing water sorption of the membrane.

  3. Synthesis and cytotoxicity of brefeldin A conjugated monomethoxy-poly(ethylene glycol)-b-poly(L-lactide) polymeric micelles.

    PubMed

    Liu, Wanyun; Wei, Junchao; Huo, Ping; Lu, Yunhua; Chen, Yiwang; Wei, Yen

    2013-01-01

    A diblock copolymer of monomethoxy-poly(ethylene glycol)-b-poly(L-lactide) (MePEG-PLLA)/brefeldin A (BFA) conjugate was synthesized by the reaction of carboxyl-terminated copolymer MePEG-PLLA with BFA in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine. The conjugation efficiency was found to be 95%. Its structure was confirmed by (1)H nuclear magnetic resonance and gel permeation chromatography. The MePEG-PLLA/BFA conjugate could self-assemble into micelles in aqueous solutions with a low critical micelle concentration of 1.8 × 10(-3 )g/L. Dynamic light scattering and transmission electron microscopy analyses of the MePEG-PLLA/BFA micelles revealed their spherical structure with an average diameter of 120 nm. The release profiles of BFA in PBS were measured by high performance liquid chromatography (HPLC), demonstrating that the controlled release of BFA can be gained for long time. The in vitro antitumor activity of the conjugate micelles against human liver carcinoma HepG2 cells was evaluated by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide method, and the results showed that BFA can be released from the conjugate micelles without losing cytotoxicity. PMID:23647253

  4. Microfluidic synthesis of thermo-responsive poly(N-isopropylacrylamide)-poly(ethylene glycol) diacrylate microhydrogels as chemo-embolic microspheres

    NASA Astrophysics Data System (ADS)

    Duck Seo, Kyoung; Kim, Dong Sung

    2014-08-01

    In this paper, we have successfully synthesized and characterized poly(N-isopropylacrylamide) (PNIPAAm)-poly(ethylene glycol) diacrylate (PEGDA) microhydrogels. Various combinations of PNIPAAm-PEGDA microhydrogels were fabricated by the generation of monodisperse microdroplets whose sizes were comparable to a blood vessel of 260 and 320 µm with the help of a hydrodynamic focusing microfluidic device (HFMD), followed by synthesis of the microhydrogels through UV irradiation to the microdroplets. The thermo-responsive behaviors of the various microhydrogels were investigated by changing the PEGDA crosslinker concentration, which was found to be a dominant factor in tuning the shrinkage ratio in response to temperature change. As an in vitro embolization performance evaluation of the microhydrogels as chemo-embolic microspheres, the deliverability of the microhydrogels through a microcatheter was first confirmed and the compact occlusion of a channel was demonstrated based on a tapered microchannel in response to the temperature increase to physiological temperature of 36 °C. The controlled release behavior of the fluorescent dye from the microhydrogel was also investigated for chemotherapeutic purposes as a proof of concept study. The PNIPAAm-PEGDA microhydrogels could be used widely in embolization procedures based on the advantages of tunable thermo-responsive and controlled release behaviors.

  5. Poly(ethylene glycol)-mediated molar mass control of short-chain- and medium-chain-length poly(hydroxyalkanoates) from Pseudomonas oleovorans.

    PubMed

    Ashby, R D; Solaiman, D K Y; Foglia, T A

    2002-10-01

    Three strains of Pseudomonas oleovorans, a well known poly(hydroxyalkanoate) (PHA) producer, were tested for the ability to control PHA molar mass and end group structure by addition of poly(ethylene glycol) (PEG) to the fermentation medium. Each strain of P. oleovorans - NRRL B-14682 (B-14682), NRRL B-14683 (B-14683), and NRRL B-778 (B-778) - synthesized a different type of PHA from oleic acid when cultured under identical growth conditions. Strain B-14682 produced poly(3-hydroxybutyrate) (PHB), while B-14683 synthesized a medium-chain-length PHA ( mcl-PHA) with a repeat unit composition ranging from C4 to C14 and some mono-unsaturation in the C14 alkyl side chains. Strain B-778 synthesized a mixture of PHB (95 mol%) and mcl-PHA (5 mol%). The addition of 0.5% (v/v) PEG (M(n) =200 g/mol, PEG-200) to the fermentation broth of strains B-14682 and B-778 resulted in chain termination through esterification at the carboxyl terminus of the PHB with PEG chain segments, thus reducing the molar mass by 54% and 23%, respectively. The molar mass of the mcl-PHA produced by strains B-14683 and B-778 also showed a 34% and 47% reduction in the presence of PEG-200, respectively, but no evidence of esterification was present. PEG-400 (M(n) =400 g/mol) had a reduced effect on PHA molar mass. In fact, the molar masses of the mcl-PHA derived from strain B-14683 and both the PHB and mcl-PHA from B-778 were unchanged by PEG-400. In contrast, the PHB produced by B-14682 showed a 35% reduction in molar mass in the presence of PEG-400. PMID:12382057

  6. Polysialic acid on neuropilin-2 is exclusively synthesized by the polysialyltransferase ST8SiaIV and attached to mucin-type o-glycans located between the b2 and c domain.

    PubMed

    Rollenhagen, Manuela; Buettner, Falk F R; Reismann, Marc; Jirmo, Adan Chari; Grove, Melanie; Behrens, Georg M N; Gerardy-Schahn, Rita; Hanisch, Franz-Georg; Mühlenhoff, Martina

    2013-08-01

    Neuropilin-2 (NRP2) is well known as a co-receptor for class 3 semaphorins and vascular endothelial growth factors, involved in axon guidance and angiogenesis. Moreover, NRP2 was shown to promote chemotactic migration of human monocyte-derived dendritic cells (DCs) toward the chemokine CCL21, a function that relies on the presence of polysialic acid (polySia). In vertebrates, this posttranslational modification is predominantly found on the neural cell adhesion molecule (NCAM), where it is synthesized on N-glycans by either of the two polysialyltransferases, ST8SiaII or ST8SiaIV. In contrast to NCAM, little is known on the biosynthesis of polySia on NRP2. Here we identified the polySia attachment sites and demonstrate that NRP2 is recognized only by ST8SiaIV. Although polySia-NRP2 was found on bone marrow-derived DCs from wild-type and St8sia2(-/-) mice, polySia was completely lost in DCs from St8sia4(-/-) mice despite normal NRP2 expression. In COS-7 cells, co-expression of NRP2 with ST8SiaIV but not ST8SiaII resulted in the formation of polySia-NRP2, highlighting distinct acceptor specificities of the two polysialyltransferases. Notably, ST8SiaIV synthesized polySia selectively on a NRP2 glycoform that was characterized by the presence of sialylated core 1 and core 2 O-glycans. Based on a comprehensive site-directed mutagenesis study, we localized the polySia attachment sites to an O-glycan cluster located in the linker region between b2 and c domain. Combined alanine exchange of Thr-607, -613, -614, -615, -619, and -624 efficiently blocked polysialylation. Restoration of single sites only partially rescued polysialylation, suggesting that within this cluster, polySia is attached to more than one site. PMID:23801331

  7. Na+ and Mg2+ ion effect on the stability of a poly I . poly A . poly I triple helix.

    PubMed

    Sorokin, Victor A; Valeev, Vladimir A; Andrus, Elena A; Gladchenko, Galina O; Blagoi, Yuri P

    2004-05-17

    Differential UV spectroscopy was used to study the temperature dependence of the conformational equilibrium in aqueous poly I . poly A . poly I (A2I) solutions containing Na+ (0.1-2 M) and Mg2+ (10(-5)-0.005 M) ions. Over the whole range of the studied Na+ and Mg2+ concentrations, the heating-induced destruction of the triple A2I helix is actually the A2I --> A + I + I (3 --> 1) transition. The rise of the transition temperature with increasing Na+ and Mg2+ contents is well described by Manning's and the "ligand" theories, which makes it possible to estimate the linear charge density on the single-stranded poly I (xi = 1.9 +/- 0.1) and the Mg2+-A2I binding constant (K = 1,250 M(-1) for the zero degree of binding). An analytical expression has been obtained, which correlates the constants of Mg2+ binding to three- and single-stranded polynucleotides (K3 and K1, respectively) and the linear charge density on them. There are only minor distinctions between the K3 values for A2U and A2I because these polynucleotides have similar structures. The difference in the K1 values is also slight as single-stranded poly U, poly I, and poly A have similar conformations. Dependence of the conformational transition temperatures of two triple helices with changing Mg2+ concentration. PMID:15468246

  8. Poly(arylene ether ketone) carrying hyperquaternized pendants: Preparation, stability and conductivity

    NASA Astrophysics Data System (ADS)

    Shen, Kunzhi; Zhang, Zhenpeng; Zhang, Haibo; Pang, Jinhui; Jiang, Zhenhua

    2015-08-01

    A new strategy to synthesize comb-shaped poly(arylene ether ketone) ionomers with hyperquaternized pendants was detailed in this work. Poly(arylene ether ketone) with electron-rich phenyl rings on the side chain was copolymerized. These electron-rich phenyl rings which could be chloromethylated and serve as precursors to cationic sites, are introduced during monomer synthesis. After chloromethylation and quaternization on the side chain, these resulting anion exchange membranes exhibit high conductivities and good dimensional stability, which benefit from the side chain type structure. The highest chloride conductivity of 0.047 S cm-1 was observed in PAEK-QTPM-30 (IEC = 1.58 mmol g-1) and swelling ratio is 31.7% at 80 °C. The structural properties of the synthesized poly(arylene ether ketone)s were investigated by 1H NMR spectroscopy. The anion exchange membranes showed excellent thermal stability up to 200 °C under nitrogen and good chemical stability for high conductivity after treating in alkaline condition up to 30 days. These membranes were studied by IEC, water uptake, dimensional stability. The nano-phase separation from ionic aggregation was confirmed by SAXS. This work implies a viable strategy to improve the performance of anion exchange membranes.

  9. Electrochemical preparation of poly(methylene blue)/graphene nanocomposite thin films

    SciTech Connect

    Erçarıkcı, Elif; Dağcı, Kader; Topçu, Ezgi; Alanyalıoğlu, Murat

    2014-07-01

    Highlights: • Poly(MB)/graphene thin films are prepared by a simple electrochemical approach. • Graphene layers in the film show a broad band in visible region of absorbance spectra. • Morphology of composite films indicates both disordered and ordered regions. • XRD reveals that nanocomposite films include rGO layers after electropolymerization process. • Chemically prepared graphene is better than electrochemically prepared graphene for electrooxidation of nitrite. - Abstract: Poly(methylene blue)/graphene nanocomposite thin films were prepared by electropolymerization of methylene blue in the presence of graphene which have been synthesized by two different methods of a chemical oxidation process and an electrochemical approach. Synthesized nanocomposite thin films were characterized by using cyclic voltammetry, UV–vis. absorption spectroscopy, powder X-ray diffraction, and scanning tunneling microscopy techniques. Electrocatalytical properties of prepared poly(methylene blue)/graphene nanocomposite films were compared toward electrochemical oxidation of nitrite. Under optimized conditions, electrocatalytical effect of nanocomposite films of chemically prepared graphene through electrochemical oxidation of nitrite was better than that of electrochemically prepared graphene.

  10. Thermoresponsive physical hydrogels of poly(lactic acid)/poly(ethylene glycol) stereoblock copolymers tuned by stereostructure and hydrophobic block sequence.

    PubMed

    Mao, Hailiang; Shan, Guorong; Bao, Yongzhong; Wu, Zi Liang; Pan, Pengju

    2016-05-18

    CBABC-type poly(lactic acid) (PLA)/poly(ethylene glycol) (PEG) pentablock copolymers composed of a central PEG block (A) and enantiomeric poly(l-lactic acid) (PLLA, B), poly(d-lactic acid) (PDLA, C) blocks were synthesized. Such pentablock copolymers form physical hydrogels at high concentrations in an aqueous solution, which stem from the aggregation and physical bridging of copolymer micelles. These gels are thermoresponsive and turn into sols upon heating. Physical gelation, gel-to-sol transition, crystalline state, microstructure, rheological behavior, biodegradation, and drug release behavior of PLA/PEG pentablock copolymers and their gels were investigated; they were also compared with PLA-PEG-PLA triblock copolymers containing the isotactic PLLA or atactic poly(d,l-lactide) (PDLLA) endblocks and PLLA-PEG-PLLA/PDLA-PEG-PDLA enantiomeric mixtures. PLA hydrophobic domains in pentablock copolymer gels changed from a homocrystalline to stereocomplexed structure as the PLLA/PDLA block length ratio approached 1/1. The gel of symmetric pentablock copolymer exhibited a wider gelation region, higher gel-to-sol transition temperature, higher hydrophobic domain crystallinity, larger intermicellar distance, higher storage modulus, and slower degradation and drug release rate compared to those of the asymmetric PLA/PEG pentablock copolymers or triblock copolymers. SAXS results indicated that the PLLA/PDLA blocks stereocomplexation in pentablock copolymers facilitated the intermicellar aggregation and bridging. Cylindrical ordered structures were observed in all the gels formed from the PLA/PEG pentablock and triblock copolymers. The stereocomplexation degree and intermicellar distance of the pentablock copolymer gels increased with heating. PMID:27121732

  11. Novel 4-Arm Poly(Ethylene Glycol)-Block-Poly(Anhydride-Esters) Amphiphilic Copolymer Micelles Loading Curcumin: Preparation, Characterization, and In Vitro Evaluation

    PubMed Central

    Shen, Yuanyuan; Li, Min; Xu, Xiaofen; Li, Mingna; Guo, Shengrong; Huang, Shengtang

    2013-01-01

    A novel 4-arm poly(ethylene glycol)-block-poly(anhydride-esters) amphiphilic copolymer (4-arm PEG-b-PAE) was synthesized by esterization of 4-arm poly(ethylene glycol) and poly(anhydride-esters) which was obtained by melt polycondensation of α-, ω-acetic anhydride terminated poly(L-lactic acid). The obtained 4-arm PEG-b-PAE was characterized by 1H-NMR and gel permeation chromatography. The critical micelle concentration of 4-arm PEG-b-PAE was 2.38 μg/mL. The curcumin-loaded 4-arm PEG-b-PAE micelles were prepared by a solid dispersion method and the drug loading content and encapsulation efficiency of the micelles were 7.0% and 85.2%, respectively. The curcumin-loaded micelles were spherical with a hydrodynamic diameter of 151.9 nm. Curcumin was encapsulated within 4-arm PEG-b-PAE micelles amorphously and released from the micelles, faster in pH 5.0 than pH 7.4, presenting one biphasic drug release pattern with rapid release at the initial stage and slow release later. The hemolysis rate of the curcumin-loaded 4-arm PEG-b-PAE micelles was 3.18%, which was below 5%. The IC50 value of the curcumin-loaded micelles against Hela cells was 10.21 μg/mL, lower than the one of free curcumin (25.90 μg/mL). The cellular uptake of the curcumin-loaded micelles in Hela cell increased in a time-dependent manner. The curcumin-loaded micelles could induce G2/M phase cell cycle arrest and apoptosis of Hela cells. PMID:23936812

  12. Physicochemical and morphological properties of poly (acrylamide) and methylcellulose hydrogels: rffects of monomer, crosslinker and polysaccharide compositions, polymer engineering and science

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper describes the physicochemical (mechanical and swelling) and morphological characterization of poly (acrylamide) and methylcellulose (PAAm-MC) hydrogels synthesized with different formulations by the free radical polymerization method. The structure-property relationship of the PAAm-MC hyd...

  13. Clarification of the blood compatibility mechanism by controlling the water structure at the blood-poly(meth)acrylate interface.

    PubMed

    Tanaka, Masaru; Mochizuki, Akira

    2010-01-01

    In previous studies, we reported that poly(2-methoxyethyl acrylate) (PMEA) exhibited excellent blood compatibility, although it has a simple chemical structure. Since then, we have been investigating the reasons for its blood compatibility. In this short review, we consider the reasons for this compatibility by comparing the structure of water in hydrated PMEA to the water structure of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(meth)acrylate analogs as reference polymers. The hydrated water in PMEA could be classified into three types; free water (or freezing water), freezing-bound water (or intermediate water), and non-freezing water (or non-freezing-bound water). We found that hydrated PMEA possessed a unique water structure, observed as cold crystallization of water in differential scanning calorimetry (DSC). Cold crystallization is interpreted as ice formation at low temperature, an attribute of freezing-bound water in PMEA. The cold crystallization peak was observed for hydrated poly(ethylene glycol) (PEG), poly(vinyl methyl ether) (PVME), polyvinylpyrrolidone (PVP), poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), poly(tetrahydrofurfuryl acrylate) (PTHFA), and newly synthesized poly(2-(2-ethoxyethoxy)ethyl acrylate), as well as various proteins and polysaccharides, which are well-known biocompatible polymers. On the other hand, cold crystallization of water was not observed in hydrated PHEMA and PMEA analogous polymers, which do not show excellent blood compatibility. Based on these findings, we hypothesized that freezing-bound water, which prevents the biocomponents from directly contacting the polymer surface or non-freezing water on the polymer surface, plays an important role in the excellent blood compatibility of PMEA. PMID:20699056

  14. A new approach to synthesize nano WC

    NASA Astrophysics Data System (ADS)

    Singh, Harjinder; Pandey, O. P.

    2013-06-01

    Tungsten carbide (WC) is extensively used in cutting and mining tools, dies and in wear resistance parts. The recent application of WC as electrocatalyst in fuel cells to replace costly nobel metal platinum (Pt) has further increased its demand. Its catalytic and mechanical properties are improved with the reduction of particle size in a nanometric range. The nano WC is synthesized from the pure precursor(s) which makes its production costly. In this work, we report a new process to get nano WC directly from the scheelite (CaWO4) ore. The powders were characterized by XRD, SEM and HRTEM.

  15. Evaluating and synthesizing broadcasting satellite systems

    NASA Technical Reports Server (NTRS)

    Knouse, G. H.

    1974-01-01

    A system model and a computer program have been developed which are representative of broadcasting satellite systems employing several types of receiving terminals. The program provides a user-oriented tool for (1) evaluating performance/cost tradeoffs, (2) synthesizing minimum cost systems for a given set of system requirements, and (3) performing sensitivity analyses to identify critical user requirements, system parameters, and technology. The types of systems which can be evaluated are described, and the capabilities of the program are illustrated by means of several examples.

  16. Analog synthesized fast-variable linear load

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    1991-01-01

    A several kilowatt power level, fast-variable linear resistor was synthesized by using analog components to control the conductance of power MOSFETs. Risetimes observed have been as short as 500 ns with respect to the control signal and 1 to 2 microseconds with respect to the power source voltage. A variant configuration of this load that dissipates a constant power set by a control signal is indicated. Replacement of the MOSFETs by static induction transistors (SITs) to increase power handling, speed and radiation hardness is discussed.

  17. (001)-orientation single crystalline Pb(Zr0.3Ti0.7)O3 pyroelectric nanorod array synthesized by hydrothermal reaction

    NASA Astrophysics Data System (ADS)

    Gui Wu, Chuan; Peng, Qiang Xiang; Sun, Xiang Yu; Meng, Jia; Yao, Shuai; Luo, Wen Bo; Li Zhang, Wan

    2015-04-01

    The fabrication and pyroelectric coefficient of Pb(Zr0.3Ti0.7)O3 (PZT) nanorod array on Nb:SrTiO3 (NSTO) substrates were reported. XRD and TEM revealed that PZT nanorods were (001) orientation single crystalline. Dense PZT nanorod array were synthesized on NSTO using optimal 0.8 g/L poly(vinyl alcohol) (PVA) and 3.2 g/L poly(acrylate acid) (PAA). Maximum pyroelectric coefficient, 5.8 × 10-9 C/(cm2·K), was measured for samples synthesized at 230 °C and poled under 5 V. The single crystalline PZT nanorod array material has potential application in small spatial (1-10 µm) infrared detectors, benefiting to achieve distinguished detector performances.

  18. Mechanism of charge transport in poly(2,5-dimethoxyaniline)

    NASA Astrophysics Data System (ADS)

    Singh, Rajiv K.; Kumar, Amit; Singh, Ramadhar

    2010-06-01

    Poly(2,5-dimethoxyaniline) (PDMA) has been synthesized by chemical oxidative polymerization technique using varying ratio of oxidants; ferric chloride (FeCl3) and ammonium persulfate [(NH4)2S2O8], in an inert atmosphere at low temperature ˜278 K. The synthesized samples of PDMA have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and by measuring its dc conductivity (σdc). The temperature dependence of dc conductivity of PDMA samples has been examined in the wide temperature range 6-303 K. The analysis of dc conductivity data reveals that in the temperature range ˜100-303 K, the dc conductivity is predominantly governed by Mott's three-dimensional variable range hopping, however, below 100 K tunneling seems to dominate. Different Mott's parameters such as characteristic temperature (T0), density of states at the Fermi level [N(EF)], the average hopping distance (R ), and the average hopping energy (W) have been estimated for all the PDMA samples and are in good agreement with the values reported earlier for other conjugated polymers.

  19. In vitro gene transfection using dendritic poly(L-lysine).

    PubMed

    Ohsaki, Mio; Okuda, Tatsuya; Wada, Akihiro; Hirayama, Toshiya; Niidome, Takuro; Aoyagi, Haruhiko

    2002-01-01

    Monodispersed dendritic poly(L-lysine)s (DPKs) of several generations were synthesized, and their characteristics as a gene transfection reagent were then investigated. The agarose gel shift and ethidium bromide titration assay proved that the DPKs of the third generation and higher could form a complex with a plasmid DNA, and the degree of compaction of the DNA was increased by the increasing number of the generation. The DPKs of the fifth and sixth generation, which have 64 and 128 amine groups on the surface of the molecule, respectively, showed efficient gene transfection ability into several cultivated cell lines without significant cytotoxity. In addition, the transfection efficiency of the DPK of the sixth generation was not seriously reduced even if serum was added at 50% of the final concentration into the transfection medium. Because we can strictly synthesize various DPK derivatives, which have several types of branch units, terminal cationic groups, and so on, they are expected to be a good object of study regarding the basic information on the detailed mechanism of gene transfection into cells. We also expect to be able to easily construct DPK-based functional gene carriers, e.g., DPKs modified by ligands such as a sugar chain, which can enable advanced gene delivery in vivo. PMID:12009940

  20. Electrochemical Interrogation of G3-Poly(propylene thiophenoimine) Dendritic Star Polymer in Phenanthrene Sensing

    PubMed Central

    Makelane, Hlamulo R.; Tovide, Oluwakemi; Sunday, Christopher E.; Waryo, Tesfaye; Iwuoha, Emmanuel I.

    2015-01-01

    A novel dendritic star-copolymer, generation 3 poly(propylene thiophenoimine) (G3PPT)-co-poly(3-hexylthiophene) (P3HT) star co-polymer on gold electrode (i.e., Au|G3PPT-co-P3HT) was used as a sensor system for the determination of phenanthrene (PHE). The G3PPT-co-P3HT star co-polymer was synthesized via in situ electrochemical co-polymerization of generation 3 poly (propylene thiophenoimine) and poly (3-hexylthiophene) on gold electrode. 1HNMR spectroscopy was used to determine the regioregularity of the polymer composites, whereas Fourier transform infrared spectroscopy and scanning electron microscopy were used to study their structural and morphological properties. Au|G3PPT-co-P3HT in the absence of PHE, exhibited reversible electrochemistry attributable to the oligo (thiophene) ‘pendants’ of the dendrimer. PHE produced an increase in the voltammetric signals (anodic currents) due to its oxidation on the dendritic material to produce catalytic current, thereby suggesting the suitability of the Au|G3PPT-co-P3HT electrode as a PHE sensor. The electrocatalysis of PHE was made possible by the rigid and planar oligo-P3HT species (formed upon the oxidation of the oligo (thiophene) pendants of the star-copolymer), which allowed the efficient capture (binding) and detection (electrocatalytic oxidation) of PHE molecules. PMID:26404296

  1. Synthesis and fabrication of a degradable poly(N-isopropyl acrylamide) scaffold for tissue engineering applications

    PubMed Central

    Galperin, Anna; Long, Thomas J.; Garty, Shai; Ratner, Buddy D.

    2013-01-01

    Biodegradable poly(N-isopropyl acrylamide) (poly-NIPAM) hydrogels with controlled molecular weight of the parent polymer and its degradation products were synthesized by atom transfer radical polymerization in the presence of a polycaprolactone-based di-chlorinated macroinitiator and polycaprolactone dimethacrylate. The phase transition temperature, swelling, hydrolytic degradability, and mechanical properties at 25 and 37°C were explored. A cytocompatibility study showed good NIH3T3 cell response over 5 days culture on the surface of the hydrogels, demonstrated by a consistent increase in cell proliferation detected by an Alamar Blue assay. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazo-lium bromide] results suggested that the hydrogels and their degradation products in the concentration range of 1–25 mg/ mL were not cytotoxic to NIH3T3 cells. A sphere-templating technique was utilized to fabricate biodegradable polyNIPAM scaffolds with monodisperse, pore size. Scaffolds with pore diameter of 48 ± 6 μm were loaded with A-10 smooth muscle cells and then warmed to 37°C entrapping cells in pores approximately 40 μm in diameter, a size we have found to be optimal for angiogenesis and biointegration. Due to their degradable nature, tunable molecular weight, highly interconnected morphology, thermally controlled monodisperse pore size, and temperature-induced volume expansion–contraction, the polyNIPAM-based scaffolds developed in this work will be valuable in tissue engineering. PMID:22961921

  2. Construction of an Immobilized Thermophilic Esterase on Epoxy Support for Poly(ε-caprolactone) Synthesis.

    PubMed

    Ren, Hui; Xing, Zhen; Yang, Jiebing; Jiang, Wei; Zhang, Gang; Tang, Jun; Li, Quanshun

    2016-01-01

    Developing an efficient immobilized enzyme is of great significance for improving the operational stability of enzymes in poly(ε-caprolactone) synthesis. In this paper, a thermophilic esterase AFEST from the archaeon Archaeoglobus fulgidus was successfully immobilized on the epoxy support Sepabeads EC-EP via covalent attachment, and the immobilized enzyme was then employed as a biocatalyst for poly(ε-caprolactone) synthesis. The enzyme loading and recovered activity of immobilized enzyme was measured to be 72 mg/g and 10.4 U/mg using p-nitrophenyl caprylate as the substrate at 80 °C, respectively. Through the optimization of reaction conditions (enzyme concentration, temperature, reaction time and medium), poly(ε-caprolactone) was obtained with 100% monomer conversion and low number-average molecular weight (Mn < 1300 g/mol). Further, the immobilized enzyme exhibited excellent reusability, with monomer conversion values exceeding 75% during 15 batch reactions. Finally, poly(ε-caprolactone) was enzymatically synthesized with an isolated yield of 75% and Mn value of 3005 g/mol in a gram-scale reaction. PMID:27322233

  3. Analysis of poly(ADP-ribose) glycohydrolase activity in nuclear extracts from mammalian cells.

    PubMed

    Bernardi, R; Rossi, L; Poirier, G G; Scovassi, A I

    1997-03-01

    We have analysed poly(ADP-ribose) glycohydrolase, the enzyme responsible for in vivo degradation of ADP-ribose polymers, by means of a biochemical assay based on the capacity of the enzyme to use a synthetic 32P-labelled polymer as a substrate. The visualization of the reaction has been achieved by separation of poly and mono(ADP-ribose) by thin-layer chromatography followed by autoradiography, whereas polymer hydrolysis has been quantified by counting the spots corresponding to poly and mono(ADP-ribose). By addition of the enzyme inhibitor ethacridine to the reaction mixture, we have confirmed the specificity of the procedure we have developed. The protocol has been applied to study the specific activity of glycohydrolase in nuclear extracts from different mammalian cell lines and to an apoptotic experimental system, namely HL60 cells treated with etoposide. We have observed the activation of the enzyme after a two-hour drug treatment, that is concomitant with the activation of poly(ADP-ribose) polymerase, the enzyme which synthesizes the polymer. These data suggest a precise regulation of ADP-ribosylation process during cell death by apoptosis. PMID:9074616

  4. Influence of the operon structure on poly(3-hydroxypropionate) synthesis in Shimwellia blattae.

    PubMed

    Andreeßen, Björn; Johanningmeier, Benjamin; Burbank, Joachim; Steinbüchel, Alexander

    2014-09-01

    Glycerol has become a cheap and abundant carbon source due to biodiesel production at a large scale, and it is available for several biotechnological applications. We recently established poly(3-hydroxypropionate) [poly(3HP)] synthesis in a recombinant Shimwellia blattae strain (Heinrich et al. Appl Environ Microbiol 79:3582-3589, 2013). The major drawbacks of the current strains are (i) low poly(3HP) yields, (ii) low plasmid stability and (iii) insufficient conversion rates. In this study, we demonstrated the influence of alterations of the operon structure, consisting of 1,3-propanediol dehydrogenase (dhaT) and aldehyde dehydrogenase (aldD) of Pseudomonas putida KT2442, propionate:coenzyme A (propionate-CoA) transferase (pct) of Clostridium propionicum X2 and polyhydroxyalkanoate (PHA) synthase (phaC1) of Ralstonia eutropha H16. It was shown that S. blattae ATCC33430/pBBR1MCS-2::dhaT::pct::aldD::phaC1 synthesized up to 14.5 % (wtPHA/wtCDW) in a 2-L fed-batch fermentation process. Furthermore, we overcame the problem of plasmid losses during the fermentation period by engineering a carbon source-dependent plasmid addiction system in a triose phosphate isomerase knockout mutant. An assumed poly(3-hydroxyalkanoic acid) degrading activity of the lipase/esterase YbfF could not be confirmed. PMID:24859521

  5. Structure/property behavior of a segmented poly(ester urethane) containing different hard segment contents

    SciTech Connect

    Orler, E. B.; Wrobleski, Debra A.; Campbell, M. S.

    2001-01-01

    A series of poly(ester urethanes) containing different hard segment contents were synthesized to provide information on the development of hard domain structure. In contrast to previous studies, this work focuses on segmented poly(ester urethanes) containing low hard segment contents. By incrementally increasing the hard segment content, we monitored the development of the hard domain structure using thermal analysis and x-ray diffraction. Rapid quenching of the samples from the melt shows that the hard and soft segments are miscible for all compositions at elevated temperatures. If the Tg of the mixed phase is greater than ambient temperature, the structure is trapped in a metastable mixed phase. Heating the materials above the Tg causes demixing and the Tg of the soft domain decreases. If the mixed phase Tg is below ambient conditions, the hard domains spontaneously phase separate. The alternating copolymer of poly(butylene adipate) (Mn = 1K) soft segment and methylene diisocyanate (MDI) (19% hard segment) shows high poly(butylene adipate) crystallinity. The addition of very small amounts of butanediol chain extender greatly inhibits soft segment crystallization. For hard segment compositions greater than 45%, hard domains crystallize.

  6. Polymer-templated mesoporous carbons synthesized in the presence of nickel nanoparticles, nickel oxide nanoparticles, and nickel nitrate

    NASA Astrophysics Data System (ADS)

    Choma, Jerzy; Jedynak, Katarzyna; Marszewski, Michal; Jaroniec, Mietek

    2012-02-01

    Mesoporous carbon composites, containing nickel and nickel oxide nanoparticles, were obtained by soft-templating method. Samples were synthesized under acidic conditions using resorcinol and formaldehyde as carbon precursors, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock co-polymer Lutrol F127 as a soft template and nickel and nickel oxide nanoparticles, and nickel nitrate as metal precursors. In addition, a one set of samples was obtained by impregnation of mesoporous carbons with a nickel nitrate solution followed by further annealing at 400 °C. Wide angle X-ray powder diffraction along with thermogravimetric analysis proved the presence of nickel nanoparticles in the final composites obtained using nickel and nickel oxide nanoparticles, and Ni(NO3)2 solution. Whereas, the impregnation of carbons with a nickel nitrate solution followed by annealing at 400 °C resulted in needle-like nickel oxide nanoparticles present inside the composites’ pores. Low-temperature (-196 °C) nitrogen physisorption, X-ray powder diffraction, and thermogravimetric analysis confirmed good adsorption and structural properties of the synthesized nickel-carbon composites, in particular, the samples possessed high surface areas (>600 m2/g), large total pore volumes (>0.50 cm3/g), and maxima of pore size distribution functions at circa 7 nm. It was found that the composites were partially graphitized during carbonization process at 850 °C. The samples are stable in an air environment below temperature of 500 °C. All these features make the synthesized nickel-carbon composites attractive materials for adsorption, catalysis, energy storage, and environmental applications.

  7. Decolourization performance in C. I. Vat Yellow 1 aqueous suspension using hydrophobically modified poly(acrylic acid).

    PubMed

    Chen, J; Chen, M C

    2011-01-01

    A series of hydrophobically modified poly(acrylic acid) (PAA), poly(2-phenoxyethyl acrylate-co-acrylic acid) (poly(PHEA-co-AA)), have been synthesized and characterized by Ubbelohde type viscometry, Nuclear Magnetic Resonance (1H NMR) spectrometry and Differential Scanning Calorimetry (DSC). The shear thinning Non-Newtonian fluid behavior of their aqueous solution and the dependence on pH and hydrophobic group contents were found through apparent viscosity and rheological property investigating. Decolourization performance in C. I. Vat Yellow 1 aqueous suspension was evaluated through visible absorbance data. Decolourization performance of hydrophobically associated polymer indicates two times better than that of PAA. The quantitative relationship was mainly studied. PMID:21866762

  8. Synthesis of dendrigraft poly(ϵ-caprolactone)s using side hydroxyl groups for the grafting of branch chains.

    PubMed

    Cheng, Juan; Ling, Xiujun; Zhong, Zhenlin; Zhuo, Renxi

    2011-11-15

    Dendrigraft poly(ϵ-caprolactone)s with high molecular weight and narrow polydispersity are synthesized via a convenient generation-growth approach. Copolymerization of ϵ-caprolactone (CL) and 4-(2-benzoxyethoxy)-ϵ-caprolactone (BECL) with stannous octanoate as a catalyst affords a functionalized poly(ϵ-caprolactone) (PCL) with benzyl-protected hydroxyl side groups. After removal of benzyl groups by palladium-catalyzed hydrogenolysis, the graft copolymerization of CL and BECL onto the hydroxyl-bearing linear polyester (zero-generation) affords the first-generation graft polyester. Further deprotection and graft polymerization cycles led to dendrigraft polyesters. Molecular weights are multiplied in each graft copolymerization. The second-generation dendrigraft poly(ϵ-caprolactone) has an M(w) of 236 000 g·mol(-1) and M(w) /M(n) of 1.53. PMID:21928304

  9. Applications of synthesized reference beam TV holography

    NASA Astrophysics Data System (ADS)

    Kornis, Janos; Nemeth, Attila; Elkahamushi, S.

    1999-08-01

    The synthesized reference beam TV holographic technique is presented in this paper. In this method synthesized reference beams are used for compensating the deformation of the investigated object. The phase-fronts of the reference beams are built from phase shifted plane waves. These phase shifted plane waves can be used periodically, so almost any phase front can be produced. The actual phase-front can be built after the measurement using recorded pictures in the computer memory. Using this technique the sensitivity of the measurement can be changed after the recording, so this feature of the method is extremely valuable in industrial measurements, where the repetition of the measurement is not always an easy task. In this way the fringe density at highly deformed points can be decreased; different components of the complicated fringe pattern can be removed; and the evaluation of the fringe system can be done more easily. This method can help to determine the sign of the deformation. A set of simulations and the results of real measurements are presented.

  10. Biogenic synthesized nanoparticles and their applications

    NASA Astrophysics Data System (ADS)

    Singh, Abhijeet; Sharma, Madan Mohan

    2016-05-01

    In the present scenario, there are growing concerns over the potential impacts of bioengineered nanoparticles in the health sector. However, our understanding of how bioengineered nanoparticles may affect organisms within natural ecosystems, lags far behind our rapidly increasing ability to engineer novel nanoparticles. To date, research on the biological impacts of bioengineered nanoparticles has primarily consisted of controlled lab studies of model organisms with single species in culture media. Here, we described a cost effective and environment friendly technique for green synthesis of silver nanoparticles. Silver nanoparticles were successfully synthesized from 1 mM AgNO3 via a green synthesis process using leaf extract as reducing as well as capping agent. Nanoparticles were characterized with the help of UV-vis absorption spectroscopy, X-ray diffraction and TEM analysis which revealed the size of nanoparticles of 30-40 nm size. Further the nanoparticles synthesized by green route are found highly toxic against pathogenic bacteria and plant pathogenic fungi viz. Escherichia coli, Pseudomonas syringae and Sclerotiniasclerotiorum. The most important outcome of this work will be the development of value-added products and protection of human health from pathogens viz., bacteria, virus, fungi etc.

  11. Synthesizing new, high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Weaver, Claire; Aronson, Meigan

    2015-03-01

    Currently, there is no accepted theory behind type-II, high-temperature superconductors, but there is a distinct relationship between anti-ferromagnetism and superconductivity. Our research focuses on synthesizing new superconducting materials by observing the link between atomic structure and magnetic moments of anti-ferromagnetic compounds and attempting to reproduce the molecular physics of these known materials in new compounds. Consider the square-planar arrangement of the transition metal Fe in the Fe-pnictide superconductors of the ZrCuSiAs ``11 11'' and the ThCr2Si2 ``122'' structure types. We believe that the physics behind this superconductor, where Fe has d6 valence electrons, contributes to the superconducting state, not the presence of Fe itself. For this reason, we are synthesizing materials containing neighboring transition metals, like Mn and Co, combined with other elements in similar crystal lattice arrangements, having ionization properties that hopefully impose d6 valence electrons on the transition metals. This project was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internships Program (SULI).

  12. New Poly(amide-imide)/Nanocomposites Reinforced Silicate Nanoparticles Based on N-pyromellitimido-L-phenyl Alanine Containing Ether Moieties

    NASA Astrophysics Data System (ADS)

    Faghihi, Khalil; Shabanian, Meisam; Dadfar, Ehsan

    2012-02-01

    A series of Poly(amide-imide)/montmorillonite nanocomposites containing N-pyromellitimido-L-phenyl alanine moiety in the main chain were synthesized by a convenient solution intercalation technique. Poly(amide-imide) (PAI) 5 as a source of polymer matrix was synthesized by the direct polycondensation reaction of N-pyromellitimido-L-phenyl alanine 3 with 4,4'-diamino diphenyl ether 4 in the presence of triphenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). The resulting nanocomposite films were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results showed that organo-modified clay was dispersed homogeneously in PAI matrix. TGA indicated an enhancement of thermal stability of new nanocomposites compared with the pure polymer.

  13. Functional Aromatic Poly(1,3,4-Oxadiazole-Ether)s with Benzimidazole Pendants: Synthesis, Thermal and Dielectric Studies

    PubMed Central

    Ganesh, Shimoga D.; Pai, Vasantakumar K.; Kariduraganavar, Mahadevappa Y.; Jayanna, Madhu B.

    2014-01-01

    Poly(1,3,4-oxadiazole-ether) with reactive carboxylic acid pendants was synthesized from solution polymerization via nucleophilic displacement polycondensation among 2,5-bis(4-fluorophenyl)-1,3,4-oxadiazole (BFPOx) and 4,4′-bis(4-hydroxyphenyl) valeric acid (BHPA). Without altering the polymeric segments, benzimidazole modified poly(1,3,4-oxadiazole-ether)s were prepared by varying stoichiometric ratios of 1,2-phenylenediamine. The molecular structural characterization of these polymers was achieved by, FT-IR, NMR, TGA, elemental analysis, and analytical techniques. The weight-average molecular weight of virgin polymer with carboxylic acid functionality was determined by gel permeation chromatography (GPC) and was found to be 22400 (Mw/Mn = 2.07). All the synthesized polyethers were compressed into pellets and electrical contacts were established to perform dielectric properties. PMID:27437448

  14. Thermal and Optical Properties of New Poly(amide-imide)/Nanocomposite Reinforced by Layer Silicate Containing Diphenyl Ether Moieties

    NASA Astrophysics Data System (ADS)

    Faghihi, Khalil; Faramarzi, Ellahe; Shabanian, Meisam

    2011-04-01

    New poly(amide-imide)-montmorillonite reinforced nanocomposites containing Bis(4-N-trimellitylimido) diphenyl ether moiety in the main chain were synthesized by a convenient solution intercalation technique. Poly(amide-imide) (PAI) 4 was synthesized by the direct polycondensation reaction of Bis(4-N-trimellitylimido) diphenyl ether 3 with 4,4'-diamino diphenyl ether 2 in the presence of triphenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PAI-nanocomposite films 4a and 4b with 10 and 20 mass% silicate particles respectively, were characterized by FT-IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The properties of nanocomposites films were investigated by using Uv-vis spectroscopy, thermogravimetric analysis (TGA) and water uptake measurements.

  15. Aqueous size exclusion chromatography in semimicro and micro-columns by newly synthesized monodisperse macroporous hydrophilic beads as a stationary phase.

    PubMed

    Gölgelioğlu, Ciğdem; Bayraktar, Aslıhan; Celebi, Bekir; Uğuzdoğan, Erdal; Tuncel, Ali

    2012-02-10

    A new class of monodisperse macroporous beads in the hydrophilic form were synthesized by seeded microsuspension copolymerization of two acrylic crosslinking agents, glycerol dimethacrylate (GDMA) and glycerol-1,3-diglycerolate diacrylate (GDGDA). The monodisperse porous poly(glycerol dimethacrylate-co-glycerol-1,3-diglycerolate diacrylate), poly(GDMA-co-GDGDA) beads were highly hydrophilic in nature due to hydroxyl functionality resulting from both crosslinking agents. The beads with different particle sizes between 4.5 and 6.7 μm and with different porous properties were obtained by changing the seed latex to monomer ratio. The bead size decreased, the average pore size increased and the specific surface area decreased with increasing seed latex to monomer ratio. Poly(GDMA-co-GDGDA) beads were slurry packed in microbore and semimicro-HPLC columns and successfully used as a stationary phase in aqueous size exclusion chromatography (SEC) mode in a micro-liquid chromatography system. The aqueous SEC runs were performed by using dextran standards in the molecular weight range of 1000-670,000 Da. SEC calibration curves exhibiting linearity in a wider range of molecular weight were obtained with the semi-micro and micro-HPLC columns packed with the poly(GDMA-co-GDGDA) beads synthesized with the seed latex to monomer ratios of 0.038 and 0.058 g/mL. The dextran standards could be eluted in an analysis time shorter than 2 min using micro or semi-micro columns packed with poly(GDMA-co-GDGDA) beads as stationary medium. These packings are suitable for molecular weight determination between 5×10(3) and 5×10(5) Da in the aqueous medium by using mobile phase flow rates in the range of 25-250 μL/min. The average molecular weight determinations of different water soluble polymers, an ionic polymer, poly(2-dimethylaminoethyl methacrylate), a zwitterionic polymer, poly([2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide), and a non-ionic polymer, poly

  16. High temperature-dependent imprint and switching mechanism of poly(vinylidene fluoride-trifluoroethylene) copolymer ultrathin films with electroactive interlayers

    NASA Astrophysics Data System (ADS)

    Zhang, Xiuli; Du, Xiaoli; Liu, Changli; Ji, Xin; Xu, Haisheng

    2015-01-01

    The imprint and switching behaviors at high temperature have been systematically investigated through the study on the poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) films without and with in-situ synthesized poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic) acid, poly(vinyl phosphonic) acid (PVPA), and copper-phthalocyanine as interlayers. The lower imprint rate and the faster switching speed are observed for the sample with PVPA as interlayer even after 107 cycles at 60 °C. Combined with the results for the imprint and switching behaviors at room temperature, the temperature-dependent imprint and switching mechanisms for different electroactive interlayers in this system are proposed. Therefore, the optimum protocol could be designed for FeRAM based on P(VDF-TrFE) film, which would be in favor of the performance and the service life of the related ferroelectric devices even at high temperature.

  17. Synthesis and characterization of sulfonated poly(ether sulfone)s containing mesonaphthobifluorene for polymer electrolyte membrane fuel cell.

    PubMed

    Lim, Youngdon; Seo, Dongwan; Lee, Soonho; Hossain, Md Awlad; Lim, Jinseong; Lee, Sangyoung; Hong, Taehoon; Kim, Whangi

    2014-10-01

    The novel sulfonated poly(ether sulfone)s containing mesonaphthobifluorene (MNF) moiety were synthesized and characterized their properties. The prepared polymers have highly conjugated aromatic structure due to the MNF group which is an allotrope of carbon and one atom thick planar sheets of sp2-bonded carbon atoms. Poly(ether sulfone)s bearing tetraphenylethylene on polymer backbone were synthesized by polycondensation and followed intra-cyclization from tetraphenylethylene to form MNF by Friedel-craft reaction with Lewis acid (FeCl3). The sulfonation was performed selectively on MNF units with conc. sulfuric acid. The structural properties of the sulfonated polymers were investigated by 1H-NMR spectroscopy. The membranes were studied by ion exchange capacity (IEC), water uptake, and proton conductivity. The synthesized polymer electrolyte membranes showed better thermal and dimensional stabilities owing to the inducted highly conjugated aromatic structure in the polymer backbone. The water uptake of the synthesized membranes ranged from 23-52%, compared with 32.13% for Nafion 211 at 80 degrees C. The synthesized membranes exhibited proton conductivities (80 degrees C, RH 90%) of 74.6-100.4 mS/cm, compared with 102.7 mS/cm for Nafion 211. PMID:25942900

  18. Synthesizing a Healable Stretchable Transparent Conductor.

    PubMed

    Li, Junpeng; Qi, Shuhua; Liang, Jiajie; Li, Lu; Xiong, Yan; Hu, Wei; Pei, Qibing

    2015-07-01

    We report the first demonstration of a healable stretchable transparent electrode comprising a silver nanowire (AgNW) network and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT) hybrid layer in the surface of a Diels-Alder elastomer substrate. The thin PEDOT layer solders the silver nanowires and confines the nanowire network in the substrate surface. The bonding between the nanowires and PEDOT is tuned via ethanol-water wetting, which allows for large-strain prestretching of the AgNW network. The composite electrode prepared via such a wetting and prestretching treatment has a figure-of-merit sheet resistance of 15 ohm/sq with 78% transmittance at 550 nm and can be stretched by 100% strain. Damages caused by razor blade cutting on the conductive surface could be healed, and the damaging-healing could be repeated for three times at the same location. The healed electrode exhibits similar resistance-strain response as the fresh electrode because of the PEDOT layer being capable of circumventing broken nanowire sites. Fatigue-induced damages after 100 cycles of 60% strain can also be healed by simple heating. PMID:26062004

  19. Synthesis, characterizations, and biocompatibility of block poly(ester-urethane)s based on biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) and poly(ε-caprolactone).

    PubMed

    Qiu, Handi; Li, Dandan; Chen, Xi; Fan, Kaiyan; Ou, Wenfeng; Chen, Kevin C; Xu, Kaitian

    2013-01-01

    A type of block poly(ester-urethane)s (abbreviated as PUBC) based on bacterial copolyester poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) and biodegradable poly(ε-caprolactone) (PCL) was synthesized by melting polymerization using 1,6-hexamethylene diisocyanate (HDI) as the coupling agent, with different 3HB, 4HB and PCL contents and segment lengths. Stannous octanoate (Sn(Oct)(2)) was used as catalyst. The chemical structure, molecular weight and thermal property were characterized by (1)H NMR, FTIR GPC, DSC and TGA. DSC analysis revealed that the PUBC polyurethanes exhibit amorphous to semi-crystalline (20.9% crystallinity degree) with T(g) range from -39.7 to -21.5 °C. The hydrophilicity was investigated by static contact angle of deionized water and CH(2)I(2). The obtained PUBCs are hydrophobic (water contact angle 73.7-90.2°). Platelet adhesion study and plasma recalcification time revealed that the block polyurethanes possess hemastasis ability. CCK-8 assay illuminated that the no cytotoxic polyurethanes maintain rat aortic smooth muscle cells (RaSMCs) good viability. It was found that the 4HB content in the materials is an important factor to affect the sustainable cell viability. PMID:22826204

  20. Synthesis and characterization of pH-sensitive poly(itaconic acid)-poly(ethylene glycol)-folate-poly(l-histidine) micelles for enhancing tumor therapy and tunable drug release.

    PubMed

    Sun, Yuan; Li, Yapeng; Nan, Shuli; Zhang, Liangzi; Huang, Hailong; Wang, Jingyuan

    2015-11-15

    pH responsive intracellular tumor targeting is increasingly investigated as a pathway to trigger the release of anti-tumor drugs once the drug carrier reached the unique acidic environment of the solid tumors or after the drug carrier has been taken up by cells, resulting in the localization of the micelles in the acidic endosomes and lysosomes. Poly(itaconic acid)-poly(ethylene glycol)-folate-poly(l-histidine) (PIA-PEG-FA-PHIS) was synthesized as a carrier for tumor-targeted drug delivery. The micelles were internalized by receptor-mediated endocytosis, and the combination of active targeting and triggered release resulted in apparent cytotoxicity and antitumor activity. The MTT assay showed DOX-loaded micelles had higher and obvious cytotoxicity against Hela cells at pH 5.0 than that at pH 7.4. Cellular uptake experiments revealed that these pH-responsive PIA-PEG-FA-PHIS micelles were taken up in great amounts by receptor-mediated endocytosis and delivered to lysosomes, triggering release of DOX into the cytoplasm. These indicated that the PIA-PEG-FA-PHIS micelles could be a promising drug delivery system with preeminent stability for targeting the hydrophobic drugs to cancer cells and releasing DOX in to the cells by sensing the acidic environment of the endosomes for cancer therapy. PMID:26210102

  1. Impact of As-Synthesized Ligands and Low-Oxygen Conditions on Silver Nanoparticle Surface Functionalization.

    PubMed

    Johnston, Kathryn A; Smith, Ashley M; Marbella, Lauren E; Millstone, Jill E

    2016-04-26

    Here, we compare the ligand exchange behaviors of silver nanoparticles synthesized in the presence of two different surface capping agents: poly(vinylpyrrolidone) (MW = 10 or 40 kDa) or trisodium citrate, and under either ambient or low-oxygen conditions. In all cases, we find that the polymer capping agent exhibits features of a weakly bound ligand, producing better ligand exchange efficiencies with an incoming thiolated ligand compared to citrate. The polymer capping agent also generates nanoparticles that are more susceptible to reactions with oxygen during both synthesis and ligand exchange. The influence of the original ligand on the outcome of ligand exchange reactions with an incoming thiolated ligand highlights important aspects of silver nanoparticle surface chemistry, crucial for applications ranging from photocatalysis to antimicrobials. PMID:27077550

  2. Nano-biocomposite films with modified cellulose nanocrystals and synthesized silver nanoparticles.

    PubMed

    Fortunati, E; Rinaldi, S; Peltzer, M; Bloise, N; Visai, L; Armentano, I; Jiménez, A; Latterini, L; Kenny, J M

    2014-01-30

    Ternary nano-biocomposite films based on poly(lactic acid) (PLA) with modified cellulose nanocrystals (s-CNC) and synthesized silver nanoparticles (Ag) have been prepared and characterized. The functionalization of the CNC surface with an acid phosphate ester of ethoxylated nonylphenol favoured its dispersion in the PLA matrix. The positive effects of the addition of cellulose and silver on the PLA barrier properties were confirmed by reductions in the water permeability (WVP) and oxygen transmission rate (OTR) of the films tested. The migration level of all nano-biocomposites in contact with food simulants were below the permitted limits in both non-polar and polar simulants. PLA nano-biocomposites showed a significant antibacterial activity influenced by the Ag content, while composting tests showed that the materials were visibly disintegrated after 15 days with the ternary systems showing the highest rate of disintegration under composting conditions. PMID:24299883

  3. Conjugated Polymers with Repeated Sequences of Group 16 Heterocycles Synthesized through Catalyst-Transfer Polycondensation.

    PubMed

    Tsai, Chia-Hua; Fortney, Andria; Qiu, Yunyan; Gil, Roberto R; Yaron, David; Kowalewski, Tomasz; Noonan, Kevin J T

    2016-06-01

    Periodic π-conjugated polymers of the group 16 heterocycles (furan, thiophene, and selenophene) were synthesized with controlled chain lengths and relatively low dispersities using catalyst-transfer polycondensation. The optical gap and redox potentials of these copolymers were fine-tuned by altering the heterocycle sequence, and atomic force microscopy revealed nanofibrillar morphologies for all the materials. Grazing incidence wide-angle X-ray scattering of the thiophene-selenophene copolymers indicated that the π-stacking distance increased with incorporation of the larger heteroatom (from ∼3.7-4.0 Å), while the lamellar spacing decreased (from ∼15.8-15.2 Å). The study also revealed that periodic sequences allow electronic properties to be tuned while retaining nanofibrillar morphologies similar to those observed for poly(3-hexylthiophene). PMID:27104362

  4. Synthesis of poly glycidylmethacrylate grafted azobenzene copolymer: Photosensitivity and nonlinear optical properties

    NASA Astrophysics Data System (ADS)

    Sousani, Abbas; Moghadam, Peyman Najafi; Hasanzadeh, Reza; Motiei, Hamideh; Bagheri, Massoumeh

    2016-01-01

    In this work poly glycidylmethacrylate grafted 4-hydroxy-4‧-methoxy-azobenzene (Azo-PGMA) was synthesized. For this propose firstly 4-hydroxy-4‧-methoxy-azobenzene (AZO) was prepared, then poly glycidylmethacrylate was prepared by free radical polymerization of glycidylmethacrylate in the presence of benzoyl peroxide as initiator under inert atmosphere in dry THF. Finally the homopolymer was functionalized by AZO moieties. The characterization of the synthesized copolymer was carried out by 1H NMR, FT-IR, thermal gravimetric analyze (TGA), differential scanning calorimetry (DSC) and optical polarizing microscope (POM) analysis. The UV-vis studies were carried out on Azo-PGMA copolymer and the results showed that the synthesized Azo-PGMA copolymer has ultra-fast response to UV light and has slow relaxation time. Also the third-order nonlinear optical properties of the Azo-PGMA copolymer and AZO were studied by using Z-scan technique. Nonlinear refraction and absorption coefficients of the above mentioned materials were measured by the closed and open aperture Z-scan method using a continuous wave Nd-YAG laser at 532 nm. The positive nonlinear absorption in Azo-PGMA and AZO was investigated at the wavelength of λ = 532 nm, respectively and the measured values of nonlinear refraction in both of the samples were from the order of 10-8 cm2/W.

  5. A two-stage enzymatic synthesis of conductive poly(3,4-ethylenedioxythiophene).

    PubMed

    Wang, Jing; Fang, Bai-Shan; Chou, Kuang-Ying; Chen, Chien-Chung; Gu, Yesong

    2014-01-10

    The conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), possesses attractive properties that show the potential applications in many fields. In this study, we have proposed a two-stage enzymatic synthesis of conductive PEDOT. Horseradish peroxidase (HRP) acts as the catalyst to promote the generation of EDOT free radicals followed by the polymerization under the room temperature in the presence of poly(sodium 4-styrenesulfonate) (PSS), then a mild heating process is employed for further chain extension. The final PEDOT:PSS is purified with n-butanol and subjected to various characterizations, which indicate that PEDOT with enzymatic approach exhibits a similar molecular structure to that with chemical method. However, the enzymatically synthesized PEDOT:PSS demonstrates advantages, such as stable integration of PEDOT with PSS and better electrochemical properties, suggesting its future prospective applications. PMID:24267567

  6. Effect of epoxidation on 30% poly(methyl methacrylate)-grafted natural rubber polymer electrolytes

    SciTech Connect

    Nazir, Khuzaimah; Aziz, Ahmad Fairoz; Adam, Nurul Ilham; Yahya, Muhd Zu Azhan; Ali, Ab Malik Marwan

    2015-08-28

    Epoxidized 30% poly(methyl methacrylate)-grafted natural rubber (EMG 30) as a polymer host in solid polymer electrolytes (SPEs) has been investigated. EMG30 was synthesized via performicepoxidation method onto 30% poly(methyl methacrylate)-grafted natural rubber (MG30) and the formations of epoxy group were discussed. The EMG30 were characterized by proton nuclear magnetic resonance ({sup 1}HNMR) to investigate their chemical structure and differential scanning calorimeter to determine their crystallinity. A new peak in {sup 1}HNMR spectra (2.71 ppm) confirmed the appearance of epoxy group. SPE based on EMG30 doped with 40 wt% LiCF{sub 3}SO{sub 3} show the highest conductivity. The complexation between EMG30 and LiCF{sub 3}SO{sub 3} were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR)

  7. Multi-responsive magnetic microsphere of poly(N-isopropylacrylamide)/carboxymethylchitosan hydrogel for drug controlled release.

    PubMed

    Rodkate, Nantharak; Rutnakornpituk, Metha

    2016-10-20

    Multi-responsive composite microspheres were synthesized via an in situ free radical polymerization of thermo-responsive poly(N-isopropylacrylamide) (poly(NIPAAm)) in the presence of carboxymethylchitosan (CMC) and magnetite nanoparticles (MNPs) followed by glutaraldehyde crosslinking. Formulation conditions of the composite microspheres were tuned such that spherical microspheres with narrow size distributions were obtained (30.0±1.0μm in diameter). They responded well to an applied magnetic field and showed water swelling responses to the change in solution pH and temperature. The release of an entrapped indomethacin model drug was accelerated when the solution temperature was above its lower critical solution temperature (LCST) (50°C) or when the solution pH was in basic conditions (pH 11). These responsive properties can be used as triggering mechanisms for releases of the entrapped drugs from the microspheres, indicating their great potentials for use in controlled release applications. PMID:27474565

  8. Multifunctional poly (lactide-co-glycolide) nanoparticles for luminescence/magnetic resonance imaging and photodynamic therapy.

    PubMed

    Lee, Dong Jin; Park, Ga Young; Oh, Kyung Taek; Oh, Nam Muk; Kwag, Dong Sup; Youn, Yu Seok; Oh, Young Taik; Park, Jin Woo; Lee, Eun Seong

    2012-09-15

    Poly (lactide-co-glycolide) (PLGA) coupled with methoxy poly (ethylene glycol) (mPEG) or chlorin e6 (Ce6) was synthesized using the Steglich esterification method. PLGA-linked mPEG (PLGA-mPEG), PLGA-linked Ce6 (PLGA-Ce6), and Fe(3)O(4) were utilized to constitute multifunctional PLGA nanoparticles (∼160 nm) via the multi-emulsion W(1)/O/W(2) (water-in-oil-in-water) method. The photo-sensitizing properties of Ce6 molecules anchored to PLGA nanoparticles enabled in vivo luminescence imaging and photodynamic therapy for the tumor site. The encapsulation of Fe(3)O(4) allowed high contrast magnetic resonance (MR) imaging of the tumor in vivo. Overall, PLGA nanoparticles resulted in a significant tumor volume regression for the light-illuminated KB tumor in vivo and enhanced the contrast at the tumor region, compared to that of Feridex(®) (commercial contrast agent). PMID:22664459

  9. Reaction efficiency and retention of poly(styrene-co-maleimide) nanoparticles deposited on fibrillated cellulose surfaces.

    PubMed

    Rastogi, Vibhore Kumar; Stanssens, Dirk; Samyn, Pieter

    2016-05-01

    Surface modification of micro- and nanofibrillated cellulose (MFC and NFC) under aqueous environment was performed by deposition of poly(styrene-co-maleimide) nanoparticles synthesized by imidization of poly(styrene-co-maleic anhydride) in presence of wax and ammonium hydroxide in variable amounts. Specifically, the influences of fiber fibrillation on nanoparticle formation (i.e., reaction efficiency) and permanent nanoparticle deposition on the fiber surface (i.e., retention) were investigated. The surface modification was mainly governed by the fiber diameter, surface charges and amount of wax. As such, the MFC affected the imidization reaction to a smaller extent (i.e., high reaction efficiency) and was more densely deposited by nanoparticles than NFC (i.e., high retention). Moreover, wax protected the fibers against fibrillation and peeling-off at high temperature and favored nanoparticle deposition. As a result, water contact angles of 142° were obtained for modified MFC in parallel with a surface coverage of 92%. PMID:26877019

  10. Thermoresponsive Random Poly(ether urethanes) with Tailorable LCSTs for Anticancer Drug Delivery.

    PubMed

    Sardon, Haritz; Tan, Jeremy P K; Chan, Julian M W; Mantione, Daniele; Mecerreyes, David; Hedrick, James L; Yang, Yi Yan

    2015-10-01

    A new class of thermoresponsive random polyurethanes is successfully synthesized and characterized. Poly(ethylene glycol) diol (Mn = 1500 Da) and 2,2-dimethylolpropionic acid are reacted with isophorone diisocyanate in the presence of methane sulfonic acid catalyst. It is found that these polyurethanes are thermoresponsive in aqueous media and manifest a lower critical solution temperature (LCST) that can be easily tuned from 30 °C to 70 °C by increasing the poly(ethylene glycol) content. Their sharp LCST transitions make these random polyurethanes ideal candidates for stimuli-responsive drug delivery applications. To that end, the ability of these systems to efficiently sequester doxorubicin (up to 36 wt%) by means of a sonication/dialysis method is successfully demonstrated. Additionally, it is also demonstrated that accelerated doxorubicin release kinetics from the nanoparticles can be attained above the LCST. PMID:26260576

  11. Extracellular poly(ADP-ribose) is a pro-inflammatory signal for macrophages

    PubMed Central

    Krukenberg, Kristin A.; Kim, Sujeong; Tan, Edwin S.; Maliga, Zoltan; Mitchison, Timothy J.

    2015-01-01

    Summary Poly(ADP-ribose) polymerase 1 (PARP1) synthesizes poly(ADP-ribose) (PAR), an essential post-translational modification whose function is important in many cellular processes including DNA damage signalling, cell death, and inflammation. All known PAR biology is intracellular, but we suspected it might also play a role in cell-to-cell communication during inflammation. We found that PAR activated cytokine release in human and mouse macrophages, a hallmark of innate immune activation, and determined structure-activity relationships. PAR was rapidly internalized by murine macrophages, while the monomer, ADP-ribose, was not. Inhibitors of TLR2 and TLR4 signaling blocked macrophage responses to PAR, and PAR induced TLR2 and TLR4 signaling in reporter cell lines suggesting it was recognized by these TLRs, much like bacterial pathogens. We propose that PAR acts as an extracellular “Damage Associated Molecular Pattern” (DAMP) that drives inflammatory signaling. PMID:25865309

  12. Synthesis and characterization of poly(ether ketone)s containing phosphorus and fluorine

    SciTech Connect

    Youngman, P.W.; Fitch, J.W.; Cassidy, P.E. |

    1996-10-01

    Because of the excellent properties exhibited by fluorinated poly(ether ketone)s, modifications were sought to further improve this polymer toward atomic oxygen resistance. For this purpose a phosphorous-containing monomer [bis(4-fluorophenyl)phenyl phosphine oxide] was synthesized and incorporated into a poly(ether ketone) backbone by reaction with 2,2-bis[4-(4-fluorobenzoyl)phenyl]hexafluoropropane in varying proportions with bisphenol AF to produce polymers with different amounts of the phosphine oxide repeating unit in the backbone. Colorless, film-forming materials were produced with a slight increase in Tg due to the phosphine oxide function. The incorporation of this moiety also resulted in a very small increase in the dielectric constant and an improved resistance to atomic oxygen ablation.

  13. Effect of epoxidation on 30% poly(methyl methacrylate)-grafted natural rubber polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Nazir, Khuzaimah; Aziz, Ahmad Fairoz; Adam, Nurul Ilham; Yahya, Muhd Zu Azhan; Ali, Ab Malik Marwan

    2015-08-01

    Epoxidized 30% poly(methyl methacrylate)-grafted natural rubber (EMG 30) as a polymer host in solid polymer electrolytes (SPEs) has been investigated. EMG30 was synthesized via performicepoxidation method onto 30% poly(methyl methacrylate)-grafted natural rubber (MG30) and the formations of epoxy group were discussed. The EMG30 were characterized by proton nuclear magnetic resonance (1HNMR) to investigate their chemical structure and differential scanning calorimeter to determine their crystallinity. A new peak in 1HNMR spectra (2.71 ppm) confirmed the appearance of epoxy group. SPE based on EMG30 doped with 40 wt% LiCF3SO3 show the highest conductivity. The complexation between EMG30 and LiCF3SO3 were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR).

  14. Synthesis and characterization of amylose grafted poly(acrylic acid) and its application in ammonia adsorption.

    PubMed

    Chen, Qing; Yu, Haojie; Wang, Li; Abdin, Zain-Ul; Yang, Xinpeng; Wang, Junhua; Zhou, Weidong; Zhang, Hongtao; Chen, Xiao

    2016-11-20

    Amylose grafted poly(acrylic acid) (Am-g-PAA) was synthesized by graft copolymerization of amylose with acrylic acid. The structure of Am-g-PAA was confirmed by (1)H NMR and FT-IR spectra. The morphology, crystallinity and thermal properties of amylose and Am-g-PAA were investigated by SEM, XRD and TGA, respectively. The highest degree of substitution (DS) of carboxyl group was 1.96 which was obtained after reacted for 1h at 60°C. Acrylic acid to anhydroglucose mole ratio for DS was 19.81. It was found that a large number of carboxyl groups were grafted on the backbone of amylose. It was also found that ammonia adsorption capacity of amylose increased by grafting poly(acrylic acid) on the backbone of amylose. PMID:27561514

  15. Poly(aryl ethers) and related polysiloxane copolymer molecular coatings: Preparation and radiation degradation

    NASA Technical Reports Server (NTRS)

    Mcgrath, J. E.

    1982-01-01

    The radiation degradation of poly(arylene ether sulfones) and related materials is studied. These basic studies are important both as a means to developing stronger, more stable matrix resins for composite materials, as well as to improve the data base in regard to chemical structure-physical property relationships. Thirty homo and copolymers were synthesized, at least partially characterized and, in several cases suitable film casting techniques were developed. Four samples were chosen for initial radiation degradation. Poly(dimethyl siloxane) soft bocks/segments can preferentially migrate to the surface of copolymer films. Since siloxanes are utilized as thermal control coatings, this form of 'molecular' coating is of interest. The chemistry for preparing such copolymers with any of the polymers described was demonstrated.

  16. Controlled release of theophylline from poly(vinyl alcohol) hydrogels/porous silicon nanostructured systems

    NASA Astrophysics Data System (ADS)

    Cervantes-Rincón, N.; Medellín-Rodríguez, F. J.; Escobar-Barrios, V. A.; Palestino, G.

    2013-03-01

    In this research, hybrid hydrogels of poly (vinyl alcohol)/ porous silicon (PSi)/theophylline were synthesized by the freezing and thawing method. We evaluated the influence of the synthesis parameters of the poly (vinyl alcohol) (PVA) hydrogels in relation to their ability to swell and drug released. The parameters studied (using an experimental design developed in Minitab 16) were the polymer concentration, the freezing temperature and the number of freezing/thawing (f/t) cycles. Nanostructured porous silicon particles (NsPSi) and theophylline were added within the polymer matrix to increase the drug charge and the polymer mechanical strength. The hybrid hydrogels were characterized by Infrared Spectroscopy Fourier Transform (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC), drug delivery kinetics were engineered according to the desired drug release schedule.

  17. Degradation of imidazolium- and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone) anion exchange membranes.

    PubMed

    Chen, Dongyang; Hickner, Michael A

    2012-11-01

    Imidazolium and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone)s were synthesized successfully with the same degree of cationic functionalization and identical polymer backbones for a comparative study of anion exchange membranes (AEMs) for solid-state alkaline membrane fuel cells (AMFCs). Both anion exchange membranes were synthesized using a new methyl-containing monomer that avoided the use of toxic chloromethylation reagents. The polymer chemical structures were confirmed by ¹H NMR and FTIR. The derived AEMs were fully characterized by water uptake, anion conductivity, stability under aqueous basic conditions, and thermal stability. Interestingly, both the cationic groups and the polymer backbone were found to be degraded in 1 M NaOH solution at 60 °C over 48 h as measured by changes of ion exchange capacity and intrinsic viscosity. Imidazolium-functionalized poly(fluorenyl ether ketone sulfone)s had similar aqueous alkaline stability to quaternary ammonium-functionalized materials at 60 °C but much lower stability at 80 °C. This work demonstrates that quaternary ammonium and imidazolium cationic groups are not stable on poly(arylene ether sulfone) backbones under relatively mild conditions. Additionally, the poly(arylene ether sulfone) backbone, which is one of the most common polymers used in ion exchange membrane applications, is not stable in the types of molecular configurations analyzed. PMID:23067022

  18. Synthesis of the first poly(diaminosulfide)s and an investigation of their applications as drug delivery vehicles

    PubMed Central

    Yoo, Jun; D’Mello, Sheetal R.; Graf, Tyler; Salem, Aliasger K.; Bowden, Ned B.

    2012-01-01

    This paper reports the first examples of poly(diaminosulfide)s that were synthesized by the reaction of a sulfur transfer reagent and several secondary diamines. The diaminosulfide group has the general structure of R2N-S-NR2 and, although it has been used in the synthesis of small molecules, it has never been utilized in the synthesis of macromolecules until this report. A series of poly(diaminosulfide)s were synthesized at elevated temperatures, and the molecular weights of the polymers were as high as 12,400 g mol−1 with conversions for the polymerization reaction up to 99%. The rate constants for the transamination reactions that lead to the polymers were measured in several solvents to provide an understanding the reaction conditions necessary to polymerize the monomers. The degradation of diaminosulfides were studied in D2O, C6D6, CD3OD, CDCl3, and DMSO-d6/D2O to demonstrate that they were very stable in organic solvents but degraded within hours under aqueous conditions. These results clearly demonstrated that diaminosulfides are very stable in organic solvents under ambient conditions. Poly(diaminosulfide)s have sufficient stabilities to be useful for many applications. The ability of these polymers to function as drug delivery vehicles were studied by the fabrication of nanoparticles of a water-insoluble poly(diaminosulfide) with a dye. The microparticles were readily absorbed into human embryonic 293 cells and possessed no measureable toxicity towards these same cells. PMID:22347726

  19. Degradation of Imidazolium- and Quaternary Ammonium-Functionalized Poly(fluorenyl ether ketone sulfone) Anion Exchange Membranes

    SciTech Connect

    Chen, DY; Hickner, MA

    2012-11-01

    Imidazolium and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone)s were synthesized successfully with the same degree of cationic functionalization and identical polymer backbones for a comparative study of anion exchange membranes (AEMs) for solid-state alkaline membrane fuel cells (AMFCs). Both anion exchange membranes were synthesized using a new methyl-containing monomer that avoided the use of toxic chloromethylation reagents. The polymer chemical structures were confirmed by H-1 NMR and FTIR. The derived AEMs were fully characterized by water uptake, anion conductivity, stability under aqueous basic conditions, and thermal stability. Interestingly, both the cationic groups and the polymer backbone were found to be degraded in 1 M NaOH solution at 60 degrees C over 48 h as measured by changes of ion exchange capacity and intrinsic viscosity. Imidazolium-functionalized poly(fluorenyl ether ketone sulfone)s had similar aqueous alkaline stability to quaternary ammonium-functionalized materials at 60 degrees C but much lower stability at 80 degrees C. This work demonstrates that quaternary ammonium and imidazolium cationic groups are not stable on poly(arylene ether sulfone) backbones under relatively mild conditions. Additionally, the poly(arylene ether sulfone) backbone, which is one of the most common polymers used in ion exchange membrane applications, is not stable in the types of molecular configurations analyzed.

  20. A Route to Aliphatic Poly(ester)s with Thiol Pendant Groups: From Monomer Design to Editable Porous Scaffolds.

    PubMed

    Fuoco, Tiziana; Finne-Wistrand, Anna; Pappalardo, Daniela

    2016-04-11

    Biodegradable aliphatic polyesters such as poly(lactide) and poly(ε-caprolactone), largely used in tissue engineering applications, lack suitable functional groups and biological cues to enable interactions with cells. Because of the ubiquity of thiol groups in the biological environment and the pliability of thiol chemistry, we aimed to design and synthesize poly(ester) chains bearing pendant thiol-protected groups. To achieve this, 3-methyl-6-(tritylthiomethyl)-1,4-dioxane-2,5-dione, a lactide-type monomer possessing a pendant thiol-protected group, was synthesized. This molecule, when used as a monomer in controlled ring-opening polymerization in combination with lactide and ε-caprolactone, appeared to be a convenient "building block" for the preparation of functionalized aliphatic copolyesters, which were easily modified further. A polymeric sample bearing pyridyl disulfide groups, able to bind a cysteine-containing peptide, was efficiently obtained from a two-step modification reaction. Porous scaffolds were then prepared by blending this latter copolymer sample with poly(l-lactide-co-ε-caprolactone) followed by salt leaching. A further disulfide exchange reaction performed in aqueous medium formed porous scaffolds with covalently linked arginine-glycine-aspartic acid sequences. The scaffolds were characterized by thermal and mechanical tests, and scanning electron microscopy surface images revealed a highly porous morphology. Moreover, a cytotoxicity test indicated good cell viability. PMID:26915640

  1. Photoinduced bending behavior of cross-linked azobenzene liquid-crystalline polymer films with a poly(oxyethylene) backbone.

    PubMed

    Lv, Jiu-an; Wang, Weiru; Xu, Jixiang; Ikeda, Tomiki; Yu, Yanlei

    2014-07-01

    Cross-linked azobenzene liquid-crystalline polymer films with a poly(oxyethylene) backbone are synthesized by photoinitiated cationic copolymerization. Azobenzene moieties in the film surface toward the light source are simultaneously photoaligned during photopolymerization with unpolarized 436 nm light and thus form a splayed alignment in the whole film. The prepared films show reversible photoinduced bending behavior with opposite bending directions when different surfaces of one film face to ultraviolet light irradiation. PMID:24771514

  2. A new synthesis of lamellar-mesostructured silica by using poly(ethylene glycol) distearate as template

    SciTech Connect

    Zhang Huanzhi; Jin Zhengwei; Wang Xiaodong

    2008-11-03

    A lamellar-mesostructured silica has been synthesized by using poly(ethylene glycol) distearate as template in ethanol solution. Highly ordered lamellar mesostructure was confirmed by X-ray diffraction pattern, transmission electronic microscopy, and nitrogen adsorption-desorption isotherm. The material obtained in this work has a large interlayer distance, and good thermal and mechanical stabilities, which can favor the preparation of the in situ polymerized nanocomposites based on intercalation of polymers in the lamellar-mesostructured silica.

  3. Algorithm That Synthesizes Other Algorithms for Hashing

    NASA Technical Reports Server (NTRS)

    James, Mark

    2010-01-01

    An algorithm that includes a collection of several subalgorithms has been devised as a means of synthesizing still other algorithms (which could include computer code) that utilize hashing to determine whether an element (typically, a number or other datum) is a member of a set (typically, a list of numbers). Each subalgorithm synthesizes an algorithm (e.g., a block of code) that maps a static set of key hashes to a somewhat linear monotonically increasing sequence of integers. The goal in formulating this mapping is to cause the length of the sequence thus generated to be as close as practicable to the original length of the set and thus to minimize gaps between the elements. The advantage of the approach embodied in this algorithm is that it completely avoids the traditional approach of hash-key look-ups that involve either secondary hash generation and look-up or further searching of a hash table for a desired key in the event of collisions. This algorithm guarantees that it will never be necessary to perform a search or to generate a secondary key in order to determine whether an element is a member of a set. This algorithm further guarantees that any algorithm that it synthesizes can be executed in constant time. To enforce these guarantees, the subalgorithms are formulated to employ a set of techniques, each of which works very effectively covering a certain class of hash-key values. These subalgorithms are of two types, summarized as follows: Given a list of numbers, try to find one or more solutions in which, if each number is shifted to the right by a constant number of bits and then masked with a rotating mask that isolates a set of bits, a unique number is thereby generated. In a variant of the foregoing procedure, omit the masking. Try various combinations of shifting, masking, and/or offsets until the solutions are found. From the set of solutions, select the one that provides the greatest compression for the representation and is executable in the

  4. Unprecedented acetoacetyl-coenzyme A synthesizing enzyme of the thiolase superfamily involved in the mevalonate pathway.

    PubMed

    Okamura, Eiji; Tomita, Takeo; Sawa, Ryuichi; Nishiyama, Makoto; Kuzuyama, Tomohisa

    2010-06-22

    Acetoacetyl-CoA is the precursor of 3-hydroxy-3-methylglutaryl (HMG)-CoA in the mevalonate pathway, which is essential for terpenoid backbone biosynthesis. Acetoacetyl-CoA is also the precursor of poly-beta-hydroxybutyrate, a polymer belonging to the polyester class produced by microorganisms. The de novo synthesis of acetoacetyl-CoA is usually catalyzed by acetoacetyl-CoA thiolase via a thioester-dependent Claisen condensation reaction between two molecules of acetyl-CoA. Here, we report that nphT7, found in the mevalonate pathway gene cluster from a soil-isolated Streptomyces sp. strain, encodes an unusual acetoacetyl-CoA synthesizing enzyme. The recombinant enzyme overexpressed in Escherichia coli catalyzes a single condensation of acetyl-CoA and malonyl-CoA to give acetoacetyl-CoA and CoA. Replacement of malonyl-CoA with malonyl-(acyl carrier protein) resulted in loss of the condensation activity. No acetoacetyl-CoA synthesizing activity was detected through the condensation of two molecules of acetyl-CoA. Based on these properties of NphT7, we propose to name this unusual enzyme of the thiolase superfamily acetoacetyl-CoA synthase. Coexpression of nphT7 with the HMG-CoA synthase gene and the HMG-CoA reductase gene in a heterologous host allowed 3.5-fold higher production of mevalonate than when only the HMG-CoA synthase and HMG-CoA reductase genes were expressed. This result suggests that nphT7 can be used to significantly increase the concentration of acetoacetyl-CoA in cells, eventually leading to the production of useful terpenoids and poly-beta-hydroxybutyrate. PMID:20534558

  5. Poly(silylene)vinylenes from ethynylhydridosilanes

    DOEpatents

    Barton, Thomas J.; Ijadi-Maghsoodi, Sina

    1992-11-10

    Catalytic polymerization of dialkyl-, alkylaryl- or diaryldiethynylhydridosilanes cleanly affords soluble poly(silylene)vinylenes which can be shaped as fibers, films and bulk objects and thermally converted to silicon carbide.

  6. Poly(silyl silane) homo and copolymers

    DOEpatents

    Zeigler, J.K.

    1991-08-13

    Poly(silyl silanes) have been prepared. They have high photosensitivity and excellent resistance to oxygen-reactive ion etching processes. They are useful as photodepolymerizable photoresists, barrier layers, etc.

  7. Poly(silyl silane) homo and copolymers

    DOEpatents

    Zeigler, John K.

    1991-01-01

    Poly(silyl silanes) have been prepared. They have high photosensitivity and excellent resistance to oxygen-reactive ion etching processes. They are useful as photodepolymerizable photoresists, barrier layers, etc.

  8. Simplification of Methods for PET Radiopharmaceutical Syntheses

    SciTech Connect

    Kilbourn, Michael, R.

    2011-12-27

    In an attempt to develop simplified methods for radiochemical synthesis of radiopharmaceuticals useful in Positron Emission Tomography (PET), current commercially available automated synthesis apparati were evaluated for use with solid phase synthesis, thin-film techniques, microwave-accelerated chemistry, and click chemistry approaches. Using combinations of these techniques, it was shown that these automated synthesis systems can be simply and effectively used to support the synthesis of a wide variety of carbon-11 and fluorine-18 labeled compounds, representing all of the major types of compounds synthesized and using all of the common radiochemical precursors available. These techniques are available for use to deliver clinically useful amounts of PET radiopharmaceuticals with chemical and radiochemical purities and high specific activities, suitable for human administration.

  9. Synthesizing Biomolecule-based Boolean Logic Gates

    PubMed Central

    Miyamoto, Takafumi; Razavi, Shiva; DeRose, Robert; Inoue, Takanari

    2012-01-01

    One fascinating recent avenue of study in the field of synthetic biology is the creation of biomolecule-based computers. The main components of a computing device consist of an arithmetic logic unit, the control unit, memory, and the input and output devices. Boolean logic gates are at the core of the operational machinery of these parts, hence to make biocomputers a reality, biomolecular logic gates become a necessity. Indeed, with the advent of more sophisticated biological tools, both nucleic acid- and protein-based logic systems have been generated. These devices function in the context of either test tubes or living cells and yield highly specific outputs given a set of inputs. In this review, we discuss various types of biomolecular logic gates that have been synthesized, with particular emphasis on recent developments that promise increased complexity of logic gate circuitry, improved computational speed, and potential clinical applications. PMID:23526588

  10. Method and apparatus for synthesizing hydrocarbons

    DOEpatents

    Colmenares, C.A.; Somorjai, G.A.; Maj, J.J.

    1983-06-21

    A method and apparatus for synthesizing a mixture of hydrocarbons having five carbons or less is disclosed. An equal molar ratio of CO and H/sub 2/ gases is caused to pass through a ThO/sub 2/ catalyst having a surface area of about 80 to 125 m/sup 2//g. The catalyst further includes Na present as a substitutional cation in an amount of about 5 to 10 atom %. At a temperature of about 340 to 360/sup 0/C, and at pressures of about 20 to 50 atm, CH/sub 3/OH is produced in an amount of about 90 wt % of the total hydrocarbon mixture, and comprised 1 mole % of the effluent gas.

  11. Methods for synthesizing metal oxide nanowires

    DOEpatents

    Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

    2016-08-09

    A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

  12. Digital frequency synthesizer for radar astronomy

    NASA Technical Reports Server (NTRS)

    Sadr, R.; Satorius, E.; Robinett, L.; Olson, E.

    1990-01-01

    The digital frequency synthesizer (DFS) is an integral part of the programmable local oscillator (PLO) which is being developed for the NASA's Deep Space Network (DSN) and radar astronomy. Here, the theory of operation and the design of the DFS are discussed, and the design parameters in application for the Goldstone Solar System Radar (GSSR) are specified. The spectral purity of the DFS is evaluated by analytically evaluating the output spectrum of the DFS. A novel architecture is proposed for the design of the DFS with a frequency resolution of 1/2(exp 48) of the clock frequency (0.35 mu Hz at 100 MHz), a phase resolution of 0.0056 degrees (16 bits), and a frequency spur attenuation of -96 dBc.

  13. Molecular scale electronics: syntheses and testing

    NASA Astrophysics Data System (ADS)

    Reinerth, William A.; Jones, LeRoy, II; Burgin, Timothy P.; Zhou, Chong-wu; Muller, C. J.; Deshpande, M. R.; Reed, Mark A.; Tour, James M.

    1998-09-01

    This paper describes four significant breakthroughs in the syntheses and testing of molecular scale electronic devices. The 16-mer of oligo(2-dodecylphenylene ethynylene) was prepared on Merrifields resin using the iterative divergent/convergent approach which significantly streamlines the preparation of this molecular scale wire. The formation of self-assembled monolayers and multilayers on gold surfaces of rigid rod conjugated oligomers that have thiol, 0957-4484/9/3/016/img11-dithiol, thioacetyl, or 0957-4484/9/3/016/img11-dithioacetyl end groups have been studied. The direct observation of charge transport through molecules of benzene-1, 4-dithiol, which have been self-assembled onto two facing gold electrodes, has been achieved. Finally, we report initial studies into what effect varying the molecular alligator clip has on the molecule scale wire's conductivity.

  14. Method and apparatus for synthesizing hydrocarbons

    DOEpatents

    Colmenares, C.A.; Somorjai, G.A.; Maj, J.J.

    1985-04-16

    A method and apparatus for synthesizing a mixture of aliphatic alcohols having five carbons or less is disclosed. An equal molar ratio of CO and H/sub 2/ gases is caused to pass through a ThO/sub 2/ catalyst having a surface area of about 80 to 125 m/sup 2//g. The catalyst further optionally includes Na ions present as substitutional cations in an amount of about 5 to 10 atom %. At a temperature of about 570 to 630/sup 0/K, and at pressures of about 20 to 50 atm, methanol and isobutanol are the predominant products and are produced in amounts of about 90 wt % of the total hydrocarbon mixture. 6 figs.

  15. Syntheses and degradations of fluorinated heterocyclics

    NASA Technical Reports Server (NTRS)

    Paciorek, K. L.; Kratzer, R. H.; Kaufman, J.; Rosser, R. W.

    1975-01-01

    The relative stability of two ring systems, the triazine rings and 1,2,4-oxadiazoles, which offer potential crosslinks useful for curing perfluoroalkyl ether elastomers, has been investigated. Tris (perfluoro-n-heptyl)-s-triazine, the perfluoroether substituted-s-triazine, 1,4-bis/(5-perfluoro-n-heptyl)-1,2,4-oxadiazolyl/benzene, its perfluoroalkyl ether substituted analog, and 3,5-bis-(perfluoro-n-heptyl)-1,2,4-oxadiazole were synthesized and subjected to thermal and oxidative degradation at 235 and 325 C and to hydrolytic degradation at 235 C. The perfluoroalkyl ether substituted triazine and 3,5-bis(perfluoro-n-heptyl)-1,2,4-oxadiazole were found to be stable under all conditions investigated.

  16. Synthesizing Earth's geochemical data for hydrogeochemical analysis

    NASA Astrophysics Data System (ADS)

    Brantley, S. L.; Kubicki, J.; Miller, D.; Richter, D.; Giles, L.; Mitra, P.

    2007-12-01

    For over 200 years, geochemical, microbiological, and chemical data have been collected to describe the evolution of the surface earth. Many of these measurements are data showing variations in time or in space. To forward predict hydrologic response to changing tectonic, climatic, or anthropogenic forcings requires synthesis of these data and utilization in hydrogeochemical models. Increasingly, scientists are attempting to synthesize such data in order to make predictions for new regions or for future time periods. However, to make such complex geochemical data accessible requires development of sophisticated cyberinfrastructures that both invite uploading as well as usage of data. Two such cyberinfrastructure (CI) initiatives are currently developing, one to invite and promote the use of environmental kinetics data (laboratory time course data) through ChemxSeer, and the other to invite and promote the use of spatially indexed geochemical data for the Earth's Critical Zone through CZEN.org. The vision of these CI initiatives is to provide cyber-enhanced portals that encourage domain scientists to upload their data before publication (in private cyberspace), and to make these data eventually publicly accessible (after an embargo period). If the CI can be made to provide services to the domain specialist - e.g. to provide data analysis services or data comparison services - we envision that scientists will upload data. In addition, the CI can promote the use and comparison of datasets across disciplines. For example, the CI can facilitate the use of spatially indexed geochemical data by scientists more accustomed to dealing with time-course data for hydrologic flow, and can provide user-friendly interfaces with CI established to facilitate the use of hydrologic data. Examples of the usage of synthesized data to predict soil development over the last 13ky and its effects on active hydrological flow boundaries in surficial systems will be discussed for i) a N

  17. Synthesized Bistatic Echo Imaging Using Phased Arrays

    NASA Astrophysics Data System (ADS)

    Soumekh, Mehrdad

    1990-01-01

    An object illuminated by a source produces a scattered signal; this signal depends upon both the source and the physical properties of the object. The problem of deducing coordinates, shape and/or certain physical properties of the object from the measurements of the returned signal is an inverse problem called echo imaging. The problem of echo imaging arises in medical imaging, remote sensing (radar; sonar; geophysical exploration), and non-destructive testing. In this paper, we address the problem of imaging an object form its returned signals using a phased array. Our approach is to exploit the array's various radiation patterns and the recordable portion of the returned signal's spectrum to generate the data base for this echo imaging system. Rapid steering of a phased array's radiation patterns can be achieved electronically. These steered waves can be utilized to synthesize waves with varying angles of propagation. In this case, the recorded returned signal for each direction of propagation can be viewed as data obtained by a bistatic array configuration. We first formulate the imaging problem for a plane wave source in a bistatic configuration. We utilize the two-way propagation time and amplitude of the returned signal to relate the object's properties, reflectivity function and coordinates, to the measured data (system modeling). This relationship is the basis for deducing the object's reflectivity function from the recorded data (inverse problem). We then extend these results for an arbitrary radiation pattern and synthesized radiation patterns generated by an array capable of beam steering in cross-range. We show that the recorded returned signals can be related to the spatial frequency contents of the reflectivity function. We also show that these array processing principles can be utilized to formulate a system model and inversion for synthetic aperture radar (SAR) imaging that incorporates wavefront curvature.

  18. A large-molecular-weight polyanion, synthesized via ring-opening metathesis polymerization, as a lubricant for human articular cartilage.

    PubMed

    Wathier, Michel; Lakin, Benjamin A; Bansal, Prashant N; Stoddart, Stephanie S; Snyder, Brian D; Grinstaff, Mark W

    2013-04-01

    A large-molecular-weight polyanion is found to possess lubricating properties for cartilage. The polyanion, sodium poly(7-oxanorbornene-2-carboxylate), is synthesized by ring-opening metathesis polymerization of methyl 5-oxanorbornene-2-carboxylate. When dissolved in aqueous solution and applied to the surface of human cartilage it reduces the friction at the interface and acts as a lubricant. Its performance is similar to that of synovial fluid and superior to those of saline and Synvisc in an ex vivo human cartilage plug-on-plug model. The polymer is also not readily degraded by hyaluronidase or cytotoxic to human chondrocytes in vitro. As such, this polymer is a new type of viscosupplement, and the results provide insight into the design requirements for synthesizing highly efficacious synthetic biolubricants. PMID:23496043

  19. Room temperature synthesized rutile TiO2 nanoparticles induced by laser ablation in liquid and their photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Liu, Peisheng; Cai, Weiping; Fang, Ming; Li, Zhigang; Zeng, Haibo; Hu, Jinlian; Luo, Xiangdong; Jing, Weiping

    2009-07-01

    TiO2 nanoparticles were prepared by one-step pulsed laser ablation of a titanium target immersed in a poly-(vinylpyrrolidone) solution at room temperature. The products were systematically characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy and x-ray photoelectron spectroscopy (XPS). The results indicated that the rutile TiO2 nanocrystalline particles were one-step synthesized at room temperature and the mean size in diameter is about 50 nm with a narrow size distribution. A probable formation process was proposed on the basis of the microstructure and the instantaneous plasma plume induced by the laser. Photocatalytic activity was monitored by degradation of a methylene blue solution. The as-prepared rutile TiO2 nanoparticles demonstrate a good photocatalytic performance. This work shows that pulsed laser ablation in liquid media is a good method to synthesize some nanosized materials which are difficult to produce by other conventional methods.

  20. Phenylethynl-terminated poly(arylene ethers)

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J. (Inventor); Bryant, Robert G. (Inventor); Hergenrother, Paul M. (Inventor)

    1993-01-01

    Phenylethynyl-terminated poly(arylene ethers) are prepared in a wide range of molecular weights by adjusting monomer ratio and adding an appropriate amount of 4-fluoro- 4'-phenylethynyl benzophenone during polymer synthesis. The resulting phenylethynyl-terminated poly(arylene ethers) react and crosslink upon curing for one hour at 350 C to provide materials with improved solvent resistance, higher modulus, and better high temperature properties than the linear, uncrosslinked polymers.

  1. Folic acid conjugated δ-valerolactone-poly(ethylene glycol) based triblock copolymer as a promising carrier for targeted doxorubicin delivery.

    PubMed

    Nair K, Lekha; Jagadeeshan, Sankar; Nair S, Asha; Kumar, G S Vinod

    2013-01-01

    The aim of this study is to test the hypothesis that the newly synthesized poly(δ-valerolactone)/poly(ethylene glycol)/poly(δ-valerolactone) (VEV) copolymer grafted with folic acid would impart targetability and further enhance the anti-tumor efficacy of doxorubicin (DOX). Here, folic acid conjugated VEV (VEV-FOL) was synthesized by a modified esterification method and characterized using IR and NMR. DOX loaded VEV-FOL micelles were synthesized using a novel solvent evaporation method and were obtained with a mean diameter of 97 nm with high encapsulation efficiency and sustained in vitro release profile. Comparative studies of polymer micelles with and without folate for cellular uptake and cytotoxicity were done on folate receptor-positive breast cancer cell line, MDAMB231. The intracellular uptake tests showed significant increase in folate micellar uptake when compared to non-folate-mediated micelles. MTT assay followed by apoptosis assays clearly indicated that folate decorated micelles showed significantly better cytotoxicity (IC50 = 0.014 µM) and efficiency to induce apoptosis than other treated groups. Moreover, a significant G2/M arrest was induced by DOX loaded VEV-FOL micelles at a concentration where free drug failed to show any activity. Thus, our results show that the folic acid-labeled VEV copolymer is a promising biomaterial with controlled and sustainable tumor targeting ability for anticancer drugs which can open new frontiers in the area of targeted chemotherapy. PMID:23990912

  2. Folic Acid Conjugated δ-Valerolactone-Poly(ethylene glycol) Based Triblock Copolymer as a Promising Carrier for Targeted Doxorubicin Delivery

    PubMed Central

    Nair K, Lekha; Jagadeeshan, Sankar; Nair S, Asha; Kumar, G. S. Vinod

    2013-01-01

    The aim of this study is to test the hypothesis that the newly synthesized poly(δ-valerolactone)/poly(ethylene glycol)/poly(δ-valerolactone) (VEV) copolymer grafted with folic acid would impart targetability and further enhance the anti-tumor efficacy of doxorubicin (DOX). Here, folic acid conjugated VEV (VEV-FOL) was synthesized by a modified esterification method and characterized using IR and NMR. DOX loaded VEV-FOL micelles were synthesized using a novel solvent evaporation method and were obtained with a mean diameter of 97 nm with high encapsulation efficiency and sustained in vitro release profile. Comparative studies of polymer micelles with and without folate for cellular uptake and cytotoxicity were done on folate receptor-positive breast cancer cell line, MDAMB231. The intracellular uptake tests showed significant increase in folate micellar uptake when compared to non-folate-mediated micelles. MTT assay followed by apoptosis assays clearly indicated that folate decorated micelles showed significantly better cytotoxicity (IC50 = 0.014 µM) and efficiency to induce apoptosis than other treated groups. Moreover, a significant G2/M arrest was induced by DOX loaded VEV-FOL micelles at a concentration where free drug failed to show any activity. Thus, our results show that the folic acid-labeled VEV copolymer is a promising biomaterial with controlled and sustainable tumor targeting ability for anticancer drugs which can open new frontiers in the area of targeted chemotherapy. PMID:23990912

  3. New Linear and Star-Shaped Thermogelling Poly([R]-3-hydroxybutyrate) Copolymers.

    PubMed

    Barouti, Ghislaine; Liow, Sing Shy; Dou, Qingqing; Ye, Hongye; Orione, Clément; Guillaume, Sophie M; Loh, Xian Jun

    2016-07-18

    The synthesis of multi-arm poly([R]-3-hydroxybutyrate) (PHB)-based triblock copolymers (poly([R]-3-hydroxybutyrate)-b-poly(N-isopropylacrylamide)-b-[[poly(methyl ether methacrylate)-g-poly(ethylene glycol)]-co-[poly(methacrylate)-g-poly(propylene glycol)

  4. Investigation of anti-corrosive properties of poly(aniline-co-2-pyridylamine-co-2,3-xylidine) and its nanocomposite poly(aniline-co-2-pyridylamine-co-2,3-xylidine)/ZnO on mild steel in 0.1 M HCl

    NASA Astrophysics Data System (ADS)

    Alam, Ruman; Mobin, Mohammad; Aslam, Jeenat

    2016-04-01

    A soluble terpolymer of aniline (AN), 2-pyridylamine (PA) and 2,3-xylidine (XY), poly(AN-co-PA-co-XY) and its nanocomposite with ZnO nanoparticles namely, poly(AN-co-PA-co-XY)/ZnO were synthesized by chemical oxidative polymerization employing ammonium persulfate as an oxidant. Nanocomposites of homopolymers, polyaniline/ZnO, poly(XY)/ZnO and poly(PA)/ZnO were also synthesized by following similar synthesis route. FTIR, XRD and SEM techniques were used to characterize the synthesized compounds. The synthesized compounds were chemically deposited on mild steel specimens by solvent evaporation method using N-methyl-2-pyrrolidone (NMP) as solvent and 10% epoxy resin (by weight) as binder. Anticorrosive properties of homopolymer nanocomposites, terpolymer and its nanocomposite coatings were studied in 0.1 M HCl by subjecting them to various corrosion tests which includes: free corrosion potential measurement (OCP), weight loss measurements, potentiodynamic polarization, and AC impedance technique. The surface morphology of the corroded and uncorroded coated steel specimens was evaluated using SEM. The corrosion protection performance of terpolymer nanocomposite coating was compared to the terpolymer and individual homopolymers nanocomposites coatings after 30 days immersion in corrosive medium.

  5. Recyclable magnetic nanocluster crosslinked with poly(ethylene oxide)-block-poly(2-vinyl-4,4-dimethylazlactone) copolymer for adsorption with antibody.

    PubMed

    Prai-In, Yingrak; Boonthip, Chatchai; Rutnakornpituk, Boonjira; Wichai, Uthai; Montembault, Véronique; Pascual, Sagrario; Fontaine, Laurent; Rutnakornpituk, Metha

    2016-10-01

    Surface modification of magnetic nanoparticle (MNP) with poly(ethylene oxide)-block-poly(2-vinyl-4,4-dimethylazlactone) (PEO-b-PVDM) diblock copolymers and its application as recyclable magnetic nano-support for adsorption with antibody were reported herein. PEO-b-PVDM copolymers were first synthesized via a reversible addition-fragmentation chain-transfer (RAFT) polymerization using poly(ethylene oxide) chain-transfer agent as a macromolecular chain transfer agent to mediate the RAFT polymerization of VDM. They were then grafted on amino-functionalized MNP by coupling with some azlactone rings of the PVDM block to form magnetic nanoclusters with tunable cluster size. The nanocluster size could be tuned by adjusting the chain length of the PVDM block. The nanoclusters were successfully used as efficient and recyclable nano-supports for adsorption with anti-rabbit IgG antibody. They retained higher than 95% adsorption of the antibody during eight adsorption-separation-desorption cycles, indicating the potential feasibility in using this novel hybrid nanocluster as recyclable support in cell separation applications. PMID:27287124

  6. Electrospinning of novel biodegradable poly(ester urethane)s and poly(ester urethane urea)s for soft tissue-engineering applications.

    PubMed

    Caracciolo, Pablo C; Thomas, Vinoy; Vohra, Yogesh K; Buffa, Fabián; Abraham, Gustavo A

    2009-10-01

    The development of biomimetic highly-porous scaffolds is essential for successful tissue engineering. Segmented poly(ester urethane)s and poly(ester urethane urea)s have been infrequently used for the fabrication of electrospun nanofibrous tissues, which is surprising because these polymers represent a very large variety of materials with tailored properties. This study reports the preparation of new electrospun elastomeric polyurethane scaffolds. Two novel segmented polyurethanes (SPU), synthesized from poly(epsilon-caprolactone) diol, 1,6-hexamethylene diisocyanate, and diester-diphenol or diurea-diol chain extenders, were used (Caracciolo et al. in J Mater Sci Mater Med 20:145-155, 2009). The spinnability and the morphology of the electrospun SPU scaffolds were investigated and discussed. The electrospinning parameters such as solution properties (polymer concentration and solvent) and processing parameters (applied electric field, needle to collector distance and solution flow rate) were optimized to achieve smooth, uniform bead-free fibers with diameter (~700 nm) mimicking the protein fibers of native extracellular matrix (ECM). The obtained elastomeric polyurethane scaffolds could be appropriate for soft tissue-engineering applications. PMID:19434481

  7. Synthesis of Externally Initiated Poly(3-alkylthiophene)s via Kumada Catalyst Transfer Polymerization

    NASA Astrophysics Data System (ADS)

    D'Avanzo, Antonella

    The ability of chemists to design and synthesize pi conjugated organic polymers with precise control over their physical and electronic properties remains the key to technological breakthroughs using polymeric material in electronic and photonic devices. Kumada catalyst transfer polymerization (KCTP) technique and Grignard metathesis (GRIM) method have enabled the synthesis of highly regioregular polymers with controlled molecular weights, narrow polydispersity index and uniform end groups. Applying this technique toward external initiation of polymers would enable the preparation of sophisticated and beneficial polymer architectures such as surface grafted polymers. This work presents an investigation of various mechanistic parameters for external initiation of poly(3-alkylthiophene). The effects of binding ligand variation on the Nickel catalyst were investigated utilizing a novel methodology allowing facile screening of ligands. Poly(3-hexylthiophene) was synthesized with high percentage initiator headgroup incorporation with triphenylphosphine ligand while the use of bidentate ligands such as diphenylphosphinopropane only resulted in quantitative initiation when ligand exchange followed initiation with the more active species. A variety of functionally substituted aryl and thiophene halides were explored for their potential to act as external small molecule initiators and the reaction intermediates were characterized via spectroscopic techniques as well as theoretical calculations. Aryl halides were found to be more stable than thiophene halides and the type and position of the initiator functionality has played a deciding role in the polymerization mechanism. Ortho substitution stabilized the aryl-Ni intermediate complex via favorable orbital overlap and kinetic effects as a result of steric hindrance were demonstrated to affect the success of the external initiation. Surface-grafted poly(3-methylthiophene) thin films were synthesized from indium tin oxide

  8. Self-associating poly(ethylene oxide)-b-poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) block copolymer for the solubilization of STAT-3 inhibitor cucurbitacin I.

    PubMed

    Mahmud, Abdullah; Patel, Sarthak; Molavi, Ommoleila; Choi, Phillip; Samuel, John; Lavasanifar, Afsaneh

    2009-03-01

    An increase in the degree of chemical compatibility between drug and polymeric structure in the core has been shown to raise the encapsulation efficiency and lower the rate of drug release from polymeric micelles. In this study, to achieve an optimized polymeric micellar delivery system for the solubilization and controlled delivery of cucurbitacin I (CuI), the Flory-Huggins interaction parameter (chi(sc)) between CuI and poly(epsilon-caprolactone) (PCL), poly(alpha-benzylcarboxylate-epsilon-caprolactone) (PBCL) and poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) (PChCL) structures was calculated by group contribution method (GCM) as an indication for the degree of chemical compatibility between different micellar core structures and CuI. The results pointed to a better compatibility between CuI and PChCL core rationalizing the synthesis of self-associating methoxy poly(ethylene oxide)-b-poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) block copolymer (MePEO-b-PChCL). Novel block copolymer of MePEO-b-PChCL was synthesized through, first, preparation of substituted monomer, that is, alpha-cholesteryl carboxylate-epsilon-caprolactone, and further ring opening polymerization of this monomer by methoxy PEO (5000 g mol(-1)) using stannous octoate as catalyst. Synthesized block copolymers were characterized for their molecular weight and polydispersity by (1)H NMR and gel permeation chromatography. Self-assembled MePEO-b-PChCL micelles were characterized for their size, morphology, critical micellar concentration (CMC), capacity for the physical encapsulation of CuI, and mode of CuI release in comparison to MePEO-b-PCL and MePEO-b-PBCL micelles. Overall, the experimental order for the level of CuI encapsulation in different polymeric micellar formulations was consistent with what was predicted by the Flory-Huggins interaction parameter. Although MePEO-b-PChCL micelles exhibited the highest level of CuI loading, this structure did not show any significant

  9. Preparation and characterization of pH-sensitive and antifouling poly(vinylidene fluoride) microfiltration membranes blended with poly(methyl methacrylate-2-hydroxyethyl methacrylate-acrylic acid).

    PubMed

    Ju, Junping; Wang, Chao; Wang, Tingmei; Wang, Qihua

    2014-11-15

    Functional terpolymer of poly(methyl methacrylate-2-hydroxyethyl methacrylate-acrylic acid) (P(MMA-HEMA-AA)) was synthesized via a radical polymerization method. The terpolymer could be directly blended with poly(vinylidene fluoride) (PVDF) to prepare the microfiltration (MF) membranes via phase separate process. The synthesized polymers were characterized by Fourier transform infrared (FTIR), the nuclear magnetic resonance proton spectra ((1)H NMR). The membrane had the typical asymmetric structure and the hydrophilic side chains tended to aggregate on the membrane surface. The surface enrichment of amphiphilic copolymer and morphology of MF membranes were characterized by Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR) and scanning electron microscopy (SEM). The contact angle (CA) and water uptake were also tested to assess the hydrophilicity and wetting characteristics of the polymer surface. The water filtration properties were measured. It was found the modified membranes showed excellent pH-sensitivity and pH-reversibility behavior. Furthermore, the hydrophilicity of the blended membranes increased, and the membranes showed good protein antifouling property. PMID:25203908

  10. Synthesis and characterization of biodegradable poly(ethylene glycol)-block-poly(5-benzyloxy-trimethylene carbonate) copolymers for drug delivery.

    PubMed

    Zeng, Faquan; Liu, Jubo; Allen, Christine

    2004-01-01

    Amphiphilic diblock copolymers with various block compositions were synthesized with monomethoxy-terminated poly(ethylene glycol) (MePEG) as the hydrophilic block and poly(5-benzyloxy-trimethylene carbonate) (PBTMC) as the hydrophobic block. When the copolymerization was conducted using MePEG as a macroinitiator and stannous 2-ethylhexanoate (Sn(Oct)2) as a catalyst, the molecular weight of the second block was uncontrollable, and the method only afforded a mixture of homopolymer and copolymer with a broad molecular weight distribution. By contrast, the use of the triethylaluminum-MePEG initiator yielded block copolymers with controllable molecular weight and a more narrow molecular weight distribution than the copolymers obtained using Sn(Oct)2. GPC and 1H NMR studies confirmed that the macroinitiator was consumed and the copolymer composition was as predicted. Two of the newly synthesized MePEG-b-PBTMC copolymers were evaluated in terms of properties primarily relating to their use in micellar drug delivery. MePEG-b-PBTMC micelles with a narrow monomodal size distribution were prepared using a high-pressure extrusion technique. The MePEG-b-PBTMC copolymers were also confirmed to be biodegradable and noncytotoxic. PMID:15360292

  11. Adsorption of biopolymers on SWCNT: ordered poly(rC) and disordered poly(rI).

    PubMed

    Karachevtsev, Maksym V; Gladchenko, Galina O; Plokhotnichenko, Alexander M; Leontiev, Victor S; Karachevtsev, Victor A

    2013-03-01

    Polymer adsorption onto single-walled carbon nanotubes (SWCNTs) depends on its rigidity/flexibility. The adsorption properties of two related homopolynucleotides poly(rI) and poly(rC) but of different rigidities were compared, employing absorption spectroscopy and molecular dynamics simulation. It was shown that adsorption of the poor base stacked poly(rI) onto the nanotube is less effective than that of the strong base stacked poly(rC), the chain of which is of higher rigidity. Analysis of UV absorption spectra of polymer:nanotube suspension at heating until 90 °C, which leads to partial nanotube aggregation because of the weakly bound polymer sliding from the tube surface, revealed that the percent of precipitated nanotubes in suspension with poly(rI) is larger than that in suspension with poly(rC) (16% vs 7%). This fact indicates the higher stability of SWCNT:poly(rC) hybrid in comparison with SWCNT:poly(rI). Less effective adsorption of poly(rI) is confirmed with a weaker hypochromic effect of nanotubes covered with poly(rI) than with poly(rC), which originates from π-π stacking of nitrogen bases with the nanotube surface. Spontaneous adsorption of oligomers on the nanotube simulated by the molecular dynamics showed that oligomer r(I)25 has a weaker energy of binding to the carbon nanotube surface than r(C)25. The oligomer with ordered bases has a tendency to form the stretched conformation along the nanotube, which provides a higher binding energy, while more flexible r(I)25 forms the stable loop spaced away from the nanotube surface, the stability of which is strengthened with H-bonding between bases. PMID:23402540

  12. Hydration effects and antifouling properties of poly(vinyl chloride-co-PEGMA) membranes studied using molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Shaikh, Abdul Rajjak; Rajabzadeh, Saeid; Matsuo, Ryuichi; Takaba, Hiromitsu; Matsuyama, Hideto

    2016-04-01

    Polyvinyl chloride (PVC) membranes are widely used in water treatment because of their low cost and chemical stability. However, PVC membranes can become fouled, and this restricts their applications in membrane technology. In order to enhance the antifouling property of PVC membranes, copolymers such as poly(vinyl chloride-co-poly(ethylene glycol)methyl ether methacrylate) (poly(VC-co-PEGMA)) with different PEGMA segment percentages were synthesized in our previous work. Experimentally, it was observed that the poly(VC-co-PEGMA) copolymer has better antifouling properties than those of PVC membranes. Here, we explore effect of the PEGMA segment percentage on the surface hydration properties of poly(VC-co-PEGMA) copolymers. Density functional theory calculations and molecular dynamics simulations were carried out to understand the interactions between PVC and PEGMA. Model structures of these systems were validated by comparing the simulated values of their volumetric properties with the experimental values. MD studies showed that increasing PEGMA percentage in the copolymer increases the interaction with water molecules, leading to improved resistance to fouling. The antifouling mechanism is also discussed with respect to surface hydration and water dynamicity. This study could form a basis for the systematic studies of polymeric membranes as well as their stability from the extent of solvent-polymer, solvent-solvent, and polymer-polymer interactions.

  13. The XRCC1 phosphate-binding pocket binds poly (ADP-ribose) and is required for XRCC1 function

    PubMed Central

    Breslin, Claire; Hornyak, Peter; Ridley, Andrew; Rulten, Stuart L.; Hanzlikova, Hana; Oliver, Antony W.; Caldecott, Keith W.

    2015-01-01

    Poly (ADP-ribose) is synthesized at DNA single-strand breaks and can promote the recruitment of the scaffold protein, XRCC1. However, the mechanism and importance of this process has been challenged. To address this issue, we have characterized the mechanism of poly (ADP-ribose) binding by XRCC1 and examined its importance for XRCC1 function. We show that the phosphate-binding pocket in the central BRCT1 domain of XRCC1 is required for selective binding to poly (ADP-ribose) at low levels of ADP-ribosylation, and promotes interaction with cellular PARP1. We also show that the phosphate-binding pocket is required for EGFP-XRCC1 accumulation at DNA damage induced by UVA laser, H2O2, and at sites of sub-nuclear PCNA foci, suggesting that poly (ADP-ribose) promotes XRCC1 recruitment both at single-strand breaks globally across the genome and at sites of DNA replication stress. Finally, we show that the phosphate-binding pocket is required following DNA damage for XRCC1-dependent acceleration of DNA single-strand break repair, DNA base excision repair, and cell survival. These data support the hypothesis that poly (ADP-ribose) synthesis promotes XRCC1 recruitment at DNA damage sites and is important for XRCC1 function. PMID:26130715

  14. The XRCC1 phosphate-binding pocket binds poly (ADP-ribose) and is required for XRCC1 function.

    PubMed

    Breslin, Claire; Hornyak, Peter; Ridley, Andrew; Rulten, Stuart L; Hanzlikova, Hana; Oliver, Antony W; Caldecott, Keith W

    2015-08-18

    Poly (ADP-ribose) is synthesized at DNA single-strand breaks and can promote the recruitment of the scaffold protein, XRCC1. However, the mechanism and importance of this process has been challenged. To address this issue, we have characterized the mechanism of poly (ADP-ribose) binding by XRCC1 and examined its importance for XRCC1 function. We show that the phosphate-binding pocket in the central BRCT1 domain of XRCC1 is required for selective binding to poly (ADP-ribose) at low levels of ADP-ribosylation, and promotes interaction with cellular PARP1. We also show that the phosphate-binding pocket is required for EGFP-XRCC1 accumulation at DNA damage induced by UVA laser, H2O2, and at sites of sub-nuclear PCNA foci, suggesting that poly (ADP-ribose) promotes XRCC1 recruitment both at single-strand breaks globally across the genome and at sites of DNA replication stress. Finally, we show that the phosphate-binding pocket is required following DNA damage for XRCC1-dependent acceleration of DNA single-strand break repair, DNA base excision repair, and cell survival. These data support the hypothesis that poly (ADP-ribose) synthesis promotes XRCC1 recruitment at DNA damage sites and is important for XRCC1 function. PMID:26130715

  15. Novel synthesis and DC electrical studies of polyindole/poly(vinyl acetate) composite films

    NASA Astrophysics Data System (ADS)

    Bhagat, D. J.; Dhokane, G. R.

    2015-01-01

    Novel one pot synthesis of polyindole/poly(vinyl acetate) composite films was prepared chemically. The monomer indole was polymerized using oxidant cupric chloride. As-synthesized composites were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscope equipped with energy dispersive X-ray spectroscopy. The DC conductivity measurements were done through two probe technique. The DC conductivity value was found to be 8.648 × 10-6 S/cm at 383 K. The transference number measurement shows that ionic conductivity was dominant over electronic conductivity.

  16. Hybridizing Poly(ε-caprolactone) and Plasmonic Titanium Nitride Nanoparticles for Broadband Photoresponsive Shape Memory Films.

    PubMed

    Ishii, Satoshi; Uto, Koichiro; Niiyama, Eri; Ebara, Mitsuhiro; Nagao, Tadaaki

    2016-03-01

    Plasmonic nanoparticles can confine light in nanoscale and locally heat the surrounding. Here we use titanium nitride (TiN) nanoparticles as broadband plasmonic light absorbers and synthesized a highly photoresponsive hybrid cross-linked polymer from shape memory polymer poly(ε-caprolactone) (PCL). The TiN-PCL hybrid is responsive to sunlight and the threshold irradiance was among the lowest when compared with other photoresponsive shape memory polymers studied previously. Sunlight heating with TiN NPs can be applied to other heat responsive smart polymers, thereby contributing to energy-saving smart polymers research for a sustainable society. PMID:26890263

  17. Photoelectrical, optical, and transport properties of poly (3-hexylthiophene)-zinc sulfide hybrid nanocomposites

    SciTech Connect

    Singh, Beerandra; Kaur, Amarjeet

    2014-08-14

    We have synthesized nanocomposites of poly (3-hexylthiophene) (P3HT) at 273 K and zinc sulfide (ZnS) nanoparticles at 353 K by the chemical route method. The synthesis of these nanocomposites is confirmed by UV-visible, high resolution transmission electron microscope, and Raman spectroscopy. We have measured photocurrent of P3HT using 50 W tungsten lamp. The photoconductivity increases with concentration of ZnS in P3HT-ZnS composite. Temperature dependent dc conductivity of P3HT and its nanocomposites have been thoroughly investigated in light of Mott's variable range hopping.

  18. Lipase-catalyzed synthesis of hyperbranched poly-L-lactide in an ionic liquid.

    PubMed

    Mena, María; López-Luna, Alberto; Shirai, Keiko; Tecante, Alberto; Gimeno, Miquel; Bárzana, Eduardo

    2013-03-01

    Hyperbranched poly-L-lactides have been synthesized by eROP in [C4MIM][PF6] media. The bis(hydroxymethyl)butyric acid molecule was used as the AB2 core co-monomer and immobilized lipase B from Candida antarctica as biocatalyst. The degree of branching could be controlled by the reaction conditions, with the maximum achieved being 0.21. The successful achievement of the hyperbranched structure is attributed to the high solvent power of substrates and products in the ionic liquid besides sustained lipase activity. PMID:22869004

  19. Synthesis and Luminescent Properties of Poly(9-(3-vinyl-phenyl)-phenanthrene).

    PubMed

    Yang, Garam; Lee, Hayoon; Lee, Suji; Jung, Hyocheol; Shin, Hwangyu; Lee, Jaehyun; Park, Jongwook

    2016-02-01

    Recently, interest of polymer light-emitting diode (PLED) fabricated from conjugated polymer has augmented because PLED has advantage property that is well-suited to flexible lighting and solution processed device. In this presentation, we suggest a new polymer host based on phenanthrene, poly(9-(3-Vinyl-phenyl)-phenanthrene) (PVPP). It can be easily synthesized through simple synthetic methods which are Suzuki and Wittig reactions. PVPP film can be obtained from spin coating with solution used by common solvent. It exhibited PL maximum value of 381 nm and broad PL spectrum. Energy transfer smoothly occurred when the three dopants for green, red and yellow were used in PVPP. PMID:27433663

  20. Physiology and molecular genetics of poly(beta-hydroxy-alkanoic acid) synthesis in Alcaligenes eutrophus.

    PubMed

    Steinbüchel, A; Schlegel, H G

    1991-03-01

    The Alcaligenes eutrophus genes for beta-ketothiolase, NADPH-dependent acetoacetyl-CoA reductase and poly(beta-hydroxybutyric acid) synthase (PHB synthase) which comprise the three-step PHB-biosynthetic pathway, were cloned. Molecular studies revealed that these genes are organized in a single operon. The A. eutrophus PHB-biosynthetic genes are readily expressed in other bacteria, and DNA fragments harbouring the operon can be used as a cartridge to confer to other bacteria the ability to synthesize PHB from acetyl-CoA. The biochemical and physiological capabilities of A. eutrophus for the synthesis of a wide variety of polyhydroxyalkanoates are discussed. PMID:2046547

  1. The Relationship Between Water Structure and Blood Compatibility in Poly(2-methoxyethyl Acrylate) (PMEA) Analogues.

    PubMed

    Sato, Kazuhiro; Kobayashi, Shingo; Kusakari, Miho; Watahiki, Shogo; Oikawa, Masahiko; Hoshiba, Takashi; Tanaka, Masaru

    2015-09-01

    Six types of poly(2-methoxyethyl acrylate) (PMEA) analogues were synthesized and the water structure in the hydrated polymers was characterized using differential scanning calorimetry (DSC). The hydrated PMEA analogues exhibited the different amounts of intermediate water. Non-thrombogenicity evaluation was performed on PMEA analogues for platelet adhesion and protein adsorption. Platelet adhesion was suppressed on PMEA analogues. In addition, the protein adsorption and deformation were suppressed by increasing the amount of intermediate water. This study demonstrates that the amount of intermediate water might play a key role in expressing the blood compatibility of polymeric materials. PMID:26017931

  2. Influence of poly(aminoquinone) on corrosion inhibition of iron in acid media

    NASA Astrophysics Data System (ADS)

    Jeyaprabha, C.; Sathiyanarayanan, S.; Phani, K. L. N.; Venkatachari, G.

    2005-11-01

    The inhibitor performance of chemically synthesized water soluble poly(aminoquinone) (PAQ) on iron corrosion in 0.5 M sulphuric acid was studied in relation to inhibitor concentration using potentiodynamic polarization and electrochemical impedance spectroscopy measurements. On comparing the inhibition performance of PAQ with that of the monomer o-phenylenediamine (OPD), the OPD gave an efficiency of 80% for 1000 ppm while it was 90% for 100 ppm of PAQ. PAQ was found to be a mixed inhibitor. Besides, PAQ was able to improve the passivation tendency of iron in 0.5 M H 2SO 4 markedly.

  3. A novel fluorescent sensor for Cr 3+ based on rhodamine-cored poly (amidoamine) dendrimer

    NASA Astrophysics Data System (ADS)

    Lei, Yonglin; Su, Yuanqiang; Huo, Jichuan

    2011-12-01

    A novel poly (amidoamine) (PAMAM) dendrimer, comprising rhodamine B unit in the core and 1-phenyl-3-methyl-5-pyrazolone unit at the periphery, has been synthesized and characterized. The dendrimer shows dramatic increase in its fluorescence intensity in the presence of proton and metal cations, especially in the presence of Cr 3+. The complex formed by dendrimer and Cr 3+ in ethanol solution has also been studied, considering the potential application for Cr 3+ fluorescent sensor. The influence of the unique chemical structure and resulted photoinduced electron transfer, as well as spirolactam ring-opening on the photophysical properties of the product has been investigated.

  4. Synthesis of poly(anilineboronic acid) nanofibers for electrochemical detection of glucose.

    PubMed

    Li, Guicun; Li, Yingmei; Peng, Hongrui; Chen, Kezheng

    2011-08-01

    Poly(anilineboronic acid) (PABA) nanofibers with U-shaped and ring-shaped morphologies have been synthesized successfully by chemical polymerization of 3-aminophenylboronic acid (APBA) in the presence of cetyltrimethylammonium bromide (CTAB) and NaF. The morphologies and sizes of PABA nanofibers can be controlled by adjusting the synthetic parameters, such as the concentrations of CTAB and APBA. The U-shaped PABA nanofibers exhibit excellent electrochemical redox activity and high sensitive detection of D-glucose in phosphate-buffered saline stock solution (pH 7.4) because of their high effective surface area as well as the high density of boronic acid groups. PMID:21692122

  5. The poly(A) polymerase GLD2 is required for spermatogenesis in Drosophila melanogaster

    PubMed Central

    Sartain, Caroline V.; Cui, Jun; Meisel, Richard P.; Wolfner, Mariana F.

    2011-01-01

    The DNA of a developing sperm is normally inaccessible for transcription for part of spermatogenesis in many animals. In Drosophila melanogaster, many transcripts needed for late spermatid differentiation are synthesized in pre-meiotic spermatocytes, but are not translated until later stages. Thus, post-transcriptional control mechanisms are required to decouple transcription and translation during spermatogenesis. In the female germline, developing germ cells accomplish similar decoupling through poly(A) tail alterations to ensure that dormant transcripts are not prematurely translated: a transcript with a short poly(A) tail will remain untranslated, whereas elongating the poly(A) tail permits protein production. In Drosophila, the ovary-expressed cytoplasmic poly(A) polymerase WISPY is responsible for stage-specific poly(A) tail extension in the female germline. Here, we examine the possibility that a recently derived testis-expressed WISPY paralog, GLD2, plays a similar role in the Drosophila male germline. We show that knockdown of Gld2 transcripts causes male sterility, as GLD2-deficient males do not produce mature sperm. Spermatogenesis up to and including meiosis appears normal in the absence of GLD2, but post-meiotic spermatid development rapidly becomes abnormal. Nuclear bundling and F-actin assembly are defective in GLD2 knockdown testes and nuclei fail to undergo chromatin reorganization in elongated spermatids. GLD2 also affects the incorporation of protamines and the stability of dynamin and transition protein transcripts. Our results indicate that GLD2 is an important regulator of late spermatogenesis and is the first example of a Gld-2 family member that plays a significant role specifically in male gametogenesis. PMID:21427144

  6. Poly(A) polymerase-based poly(A) length assay

    PubMed Central

    Patil, Deepak P.; Bakthavachalu, Baskar; Schoenberg, Daniel R.

    2013-01-01

    Summary mRNA polyadenylation functions in nuclear export, translation and stability. We describe an efficient protocol designed to assess poly(A) tail length that is based on 3' tailing by yeast poly(A) polymerase and product analysis to single-nucleotide resolution by capillary electrophoresis. PMID:24590776

  7. SYNTHESES OF CROSSLINKABLE POLY(CARBOSILANE/SILOXANE)S BY HYDROSILATION IN TOLUENE AND SUPERCRITICAL CARBON DIOXIDE. (R825503)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  8. Mechanism of Cis-Inhibition of PolyQ Fibrillation by PolyP: PPII Oligomers and the Hydrophobic Effect

    PubMed Central

    Darnell, Gregory D.; Derryberry, JohnMark; Kurutz, Josh W.; Meredith, Stephen C.

    2009-01-01

    Abstract PolyQ peptides teeter between polyproline II (PPII) and β-sheet conformations. In tandem polyQ-polyP peptides, the polyP segment tips the balance toward PPII, increasing the threshold number of Gln residues needed for fibrillation. To investigate the mechanism of cis-inhibition by flanking polyP segments on polyQ fibrillation, we examined short polyQ, polyP, and tandem polyQ-polyP peptides. These polyQ peptides have only three glutamines and cannot form β-sheet fibrils. We demonstrate that polyQ-polyP peptides form small, soluble oligomers at high concentrations (as shown by size exclusion chromatography and diffusion coefficient measurements) with PPII structure (as shown by circular dichroism spectroscopy and 3JHN-Cα constants of Gln residues from constant time correlation spectroscopy NMR). Nuclear Overhauser effect spectroscopy and molecular modeling suggest that self-association of these peptides occurs as a result of both hydrophobic and steric effects. Pro side chains present three methylenes to solvent, favoring self-association of polyP through the hydrophobic effect. Gln side chains, with two methylene groups, can adopt a conformation similar to that of Pro side chains, also permitting self-association through the hydrophobic effect. Furthermore, steric clashes between Gln and Pro side chains to the C-terminal side of the polyQ segment favor adoption of the PPII-like structure in the polyQ segment. The conformational adaptability of the polyQ segment permits the cis-inhibitory effect of polyP segments on fibrillation by the polyQ segments in proteins such as huntingtin. PMID:19843462

  9. Chemical syntheses of inulin and levan structures.

    PubMed

    Oscarson, Stefan; Sehgelmeble, Fernando W

    2002-11-29

    A fructofuranosyl thiglycoside donor, ethyl 6-O-acetyl-3-O-benzyl-1,4-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)-2-thio-beta-D-fructofuranoside (11), designed to yield stereospecifically beta-linkages and also to allow subsequent elongation in the 6- and/or 1-positions, was prepared and used in syntheses of levan and inulin structures. DMTST-promoted glycosylation between 11 (1.3 mol equiv) and methyl beta-D-fructofuranoside 6-OH and 1-OH acceptors (3 and 6) gave stereospecifically the protected methyl levanobioside 12 and inulinobioside 17 in excellent yields (80 and 86%), respectively. Protecting group manipulations on these afforded new disaccharide 6'-OH and 1'-OH acceptors (13 and 19), which were coupled again with donor 11 (1.0 mol equiv) to yield methyl levanotrioside 14 and inulinotrioside 20 in high yields, 65 and 67%, respectively. These were transformed into new acceptors and also fully deprotected to afford the methyl glycosides of levanotriose and inulinotriose, all structures that have earlier not been accessible by chemical synthesis. PMID:12444625

  10. Multistep sintering to synthesize fast lithium garnets

    NASA Astrophysics Data System (ADS)

    Xu, Biyi; Duan, Huanan; Xia, Wenhao; Guo, Yiping; Kang, Hongmei; Li, Hua; Liu, Hezhou

    2016-01-01

    A multistep sintering schedule is developed to synthesize Li7La3Zr2O12 (LLZO) doped with 0.2 mol% Al3+. The effect of sintering steps on phase, relative density and ionic conductivity of Al-doped LLZO has been evaluated using powder X-Ray diffraction (XRD), scanning electron microscopy (SEM), 27Al magic spinning nuclear magnetic resonance (NMR) spectroscopy and electrochemical impedance spectroscopy (EIS). The results show that by holding the sample at 900 °C for 6 h, the mixture of tetragonal and cubic garnet phases are obtained; by continuously holding at 1100 °C for 6 h, the tetragonal phase completely transforms into cubic phase; by holding at 1200 °C, the relative density increases without decomposition of the cubic phase. The Al-LLZO pellets after multistep sintering exhibit cubic phase, relative density of 94.25% and ionic conductivity of 4.5 × 10-4 S cm-1 at room temperature. Based on the observation, a sintering model is proposed and discussed.

  11. Multilayer graphane synthesized under high hydrogen pressure

    DOE PAGESBeta

    Antonov, V. E.; Bashkin, I. O.; Bazhenov, A. V.; Bulychev, B. M.; Fedotov, V. K.; Fursova, T. N.; Kolesnikov, A. I.; Kulakov, V. I.; Lukashev, R. V.; Matveev, D. V.; et al

    2015-12-19

    A new hydrocarbon – hydrographite – with the composition close to CH is shown to form from graphite and gaseous hydrogen at pressures above 2 GPa and temperatures from 450 to 700 °C. Hydrographite is a black solid thermally stable under ambient conditions. When heated in vacuum, it decomposes into graphite and molecular hydrogen at temperatures from 500 to 650 °C. Powder X-ray diffraction characterizes hydrographite as a multilayer “graphane II” phase predicted by ab initio calculations [Wen X-D et al. PNAS 2011; 108:6833] and consisting of graphane sheets in the chair conformation stacked along the hexagonal c axis inmore » the -ABAB- sequence. The crystal structure of the synthesized phase belongs to the P63mc space group. Moreover, the unit cell parameters are a = 2.53(1) Å and c = 9.54(1) Å and therefore exceed the corresponding parameters of graphite by 2.4(2)% and 42.0(3)%. Stretching vibrations of C–H groups on the surface of the hydrographite particles are examined by infrared spectroscopy.« less

  12. Multilayer graphane synthesized under high hydrogen pressure

    SciTech Connect

    Antonov, V. E.; Bashkin, I. O.; Bazhenov, A. V.; Bulychev, B. M.; Fedotov, V. K.; Fursova, T. N.; Kolesnikov, A. I.; Kulakov, V. I.; Lukashev, R. V.; Matveev, D. V.; Sakharov, M. K.; Shulga, Y. M.

    2015-12-19

    A new hydrocarbon – hydrographite – with the composition close to CH is shown to form from graphite and gaseous hydrogen at pressures above 2 GPa and temperatures from 450 to 700 °C. Hydrographite is a black solid thermally stable under ambient conditions. When heated in vacuum, it decomposes into graphite and molecular hydrogen at temperatures from 500 to 650 °C. Powder X-ray diffraction characterizes hydrographite as a multilayer “graphane II” phase predicted by ab initio calculations [Wen X-D et al. PNAS 2011; 108:6833] and consisting of graphane sheets in the chair conformation stacked along the hexagonal c axis in the -ABAB- sequence. The crystal structure of the synthesized phase belongs to the P63mc space group. Moreover, the unit cell parameters are a = 2.53(1) Å and c = 9.54(1) Å and therefore exceed the corresponding parameters of graphite by 2.4(2)% and 42.0(3)%. Stretching vibrations of C–H groups on the surface of the hydrographite particles are examined by infrared spectroscopy.

  13. Legionella bozemanae synthesizes phosphatidylcholine from exogenous choline.

    PubMed

    Palusinska-Szysz, Marta; Janczarek, Monika; Kalitynski, Rafal; Dawidowicz, Andrzej L; Russa, Ryszard

    2011-02-20

    The phospholipid class and fatty acid composition of Legionella bozemanae were determined using thin-layer chromatography, gas-liquid chromatography, and matrix-assisted laser desorption ionization-time of flight mass spectrometry. Phosphatidylcholine, phosphatidylethanolamine, and diphosphatidylglycerol were the predominant phospholipids, while phosphatidyl-N-monomethylethanolamine, phosphatidylglycerol, and phosphatidyl-N,N-dimethylethanolamine were present at low concentrations. With the use of the LC/MS technique, PC16:0/15:0, PC17:/15:0, and PE16:1/15:0 were shown to be the dominant phospholipid constituents, which may be taxonomically significant. Two independent phosphatidylcholine synthesis pathways (the three-step methylation and the one-step CDP-choline pathway) were present and functional in L. bozemanae. In the genome of L. bozemanae, genes encoding two potential phosphatidylcholine forming enzymes, phospholipid N-methyl transferase (PmtA) and phosphatidylcholine synthase (Pcs), homologous to L. longbeachae, L. drancourtii, and L. pneumophila pmtA and pcs genes were identified. Genes pmtA and pcs from L. bozemanae were sequenced and analyzed on nucleotide and amino acid levels. Bacteria grown on an artificial medium with labelled choline synthesized phosphatidylcholine predominantly via the phosphatidylcholine synthase pathway, which indicates that L. bozemanae phosphatidylcholine, similarly as in other bacteria associated with eukaryotes, is an important determinant of host-microbe interactions. PMID:20338739

  14. Efficacy of some synthesized thiazoles against dermatophytes.

    PubMed

    Ouf, S A; Taleb, A M Abu; Tharwat, N A; Geweely, N S

    2013-12-01

    Twelve thiazoles and their fused derivatives were tested for their antimicrobial activity against Trichophyton rubrum, T. terrestre, Epidermophyton floccosum, and Microsporum gypseum. Most of the synthesized compounds were inhibitory to the tested fungi. The most effective compound was 5-(4-ethoxybenzylidene-4,5-dihydro-4-oxothiazol-2-yl)-N,3-diphenylbut-2-namide (3c) followed by 2-(4-oxo-4,5-dihydrothiazol-2-yl)-3-phenyl-but-2-enoic acid-(3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-amide (2b). These compounds were more efficacious than terbinafine, the reference drug. The tested compounds caused variable reduction in the activity of keratinase of the dermatophytes, depending on the azole derivative and the test fungus. Thiazole derivatives (2b) and (3c) exhibited the highest efficacy in decreasing ergosterol biosynthesis of the tested dermatophytes. The treatment of guinea pigs with compound (3c) induced complete curing in the case of all the test dermatophytes 30days post-treatment. The percent curing for compounds (3c) and (2b) was better than the reference drug. PMID:24129248

  15. Oligodendrocyte Precursor Cells Synthesize Neuromodulatory Factors

    PubMed Central

    Sakry, Dominik; Yigit, Hatice; Dimou, Leda; Trotter, Jacqueline

    2015-01-01

    NG2 protein-expressing oligodendrocyte progenitor cells (OPC) are a persisting and major glial cell population in the adult mammalian brain. Direct synaptic innervation of OPC by neurons throughout the brain together with their ability to sense neuronal network activity raises the question of additional physiological roles of OPC, supplementary to generating myelinating oligodendrocytes. In this study we investigated whether OPC express neuromodulatory factors, typically synthesized by other CNS cell types. Our results show that OPC express two well-characterized neuromodulatory proteins: Prostaglandin D2 synthase (PTGDS) and neuronal Pentraxin 2 (Nptx2/Narp). Expression levels of the enzyme PTGDS are influenced in cultured OPC by the NG2 intracellular region which can be released by cleavage and localizes to glial nuclei upon transfection. Furthermore PTGDS mRNA levels are reduced in OPC from NG2-KO mouse brain compared to WT cells after isolation by cell sorting and direct analysis. These results show that OPC can contribute to the expression of these proteins within the CNS and suggest PTGDS expression as a downstream target of NG2 signaling. PMID:25966014

  16. Sequence determination of synthesized chondroitin sulfate dodecasaccharides.

    PubMed

    Shioiri, Tatsumasa; Tsuchimoto, Jun; Watanabe, Hideto; Sugiura, Nobuo

    2016-06-01

    Chondroitin sulfate (CS) is a linear acidic polysaccharide composed of repeating disaccharide units of glucuronic acid and N-acetyl-d-galactosamine. The polysaccharide is modified with sulfate groups at different positions by a variety of sulfotransferases. CS chains exhibit various biological and pathological functions by interacting with cytokines and growth factors and regulating their signal transduction. The fine structure of the CS chain defines its specific biological roles. However, structural analysis of CS has been restricted to disaccharide analysis, hampering the understanding of the structure-function relationship of CS chains. Here, we chemo-enzymatically synthesized CS dodecasaccharides having various sulfate modifications using a bioreactor system of bacterial chondroitin polymerase mutants and various CS sulfotransferases. We developed a sequencing method for CS chains using the CS dodecasaccharides. The method consists of (i) labeling a reducing end with 2-aminopyridine (PA), (ii) partial digestion of CS with testicular hyaluronidase, followed by separation of PA-conjugated oligosaccharides with different chain lengths, (iii) limited digestion of these oligosaccharides with chondroitin lyase AC II into disaccharides, followed by labeling with 2-aminobenzamide, (iv) CS disaccharide analysis using a dual-fluorescence HPLC system (reversed-phase ion-pair and ion-exchange chromatography), and (v) estimation of the composition by calculating individual disaccharide ratios. This CS chain sequencing allows characterization of CS-modifying enzymes and provides a useful tool toward understanding the structure-function relationship of CS chains. PMID:26791444

  17. Signal Enhancement of Abiotically-Synthesized RNA Oligonucleotides and other Biopolymers using Unmodified Fused Silica in MALDI-MS

    NASA Astrophysics Data System (ADS)

    Cassidy, Lauren M.; Dong, Yingying; Joshi, Prakash C.; Aldersley, Michael F.; Ferris, James P.; McGown, Linda B.

    2011-06-01

    Metal is the standard desorption platform for MALDI-MS but other surfaces have been shown to offer advantages for particular types of analytes or applications. One such substrate is fused silica, which has been employed for matrix-free detection of low mass analytes and for affinity MALDI-MS in which binding ligands are immobilized at the fused silica surface. The present work reports improved MALDI-MS detection of RNA oligonucleotides, including polyA, polyU, and polyA/U, at the high end of the mass range when unmodified fused silica is used instead of stainless steel as the MALDI target. The RNA oligonucleotides were abiotically synthesized from activated monomers on catalytic clay surfaces. Further investigation found enhanced signals as well for other anionic biopolymers, including DNA oligonucleotides and heparin. Enhancement also was observed for dextran, which is neutral, indicating that the effect is not restricted to anionic biopolymers. Among more general analytical applications, the results are particularly relevant to rapid screening of abiotic RNA polymerization toward elucidating pathways to life on Earth.

  18. Thermodynamics of Polymer Adsorption onto Nanoporous Silica and its Application in the Large Scale Purification of Poly(styrene)-block-Poly(alkyl methacrylate) Diblock Copolymers

    NASA Astrophysics Data System (ADS)

    Abdulahad, Asem Irfan

    As a result of unavoidable inconsistencies in their synthesis via controlled radical polymerization techniques, block copolymers inherently have distributions in chemical composition and molecular weight in each block that can have significant impact on their viscoelastic properties as well as their ability to self-assemble into ordered phases. High performance liquid chromatography is routinely utilized for determining the average molecular weight distribution that exist in synthetic polymers and is becoming increasingly popular for the fractionation and purification of chemically diverse complex polymer materials such as diblock copolymers. However, the inability of HPLC fractionation to provide meaningful quantities of purified complex polymers makes this method extremely inefficient and limits the ability to characterize purified fractions further. Overall, this dissertation work can be digested in two distinct parts. In the first part, high performance liquid chromatography was used as a tool for studying the influential parameters affecting the critical adsorption point of poly(styrene) and poly(alkyl methacrylate) homopolymers. The understanding gained in the first portion was depended on for the development of large scale fractionation procedures. In the second part, a chemically diverse variety of poly(alkyl methacrylate)-block-poly(styrene) diblock copolymers synthesized by atom transfer radical polymerization and anionic polymerization were purified by large scale adsorption-based fractionation procedures that included chromatographic filtration and the sequential adsorption/desorption of bulk diblock copolymer materials. The impact of diblock copolymer purification is addressed by comparing the molecular weight distribution, chemical composition distribution, viscoelastic properties, and small-angle X-ray scattering profiles.

  19. TiO2/PCL hybrid materials synthesized via sol-gel technique for biomedical applications.

    PubMed

    Catauro, M; Bollino, F; Papale, F; Marciano, S; Pacifico, S

    2015-02-01

    The aim of the present work has been the synthesis of organic/inorganic hybrid materials based on titanium dioxide and poly(ε-caprolactone) (PCL) to be used in the biomedical field. Several materials have been synthesized using sol-gel methods by adding different amounts of polymer to the inorganic sol. The obtained gels have been characterized using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The FT-IR data allowed us to hypothesize that the structure formed was that of an interpenetrating network, realized by hydrogen bonds between TiOH groups in the sol-gel intermediate species and carbonyl groups in the polymer repeating units. SEM and AFM analyses highlighted that the obtained materials were nanostructurated hybrids. To evaluate the biological properties of the hybrids, their bioactivity and cytotoxicity were investigated as a function of the PCL amount. The bioactivity of the synthesized systems was proven by the formation of a hydroxyapatite layer on the surface of samples soaked in a fluid simulating human blood plasma (SBF). MTT cytotoxicity tests and Trypan Blue dye exclusion tests were carried out exposing NIH-3T3 mouse embryonic fibroblasts for 24 and 48h to extracts from the investigated hybrid materials. The results showed that all the hybrids had a non-cytotoxic effect on target cells. PMID:25492181

  20. Chitosan grafted methoxy poly(ethylene glycol)-poly(ε-caprolactone) nanosuspension for ocular delivery of hydrophobic diclofenac

    PubMed Central

    Shi, Shuai; Zhang, Zhaoliang; Luo, Zichao; Yu, Jing; Liang, Renlong; Li, Xingyi; Chen, Hao

    2015-01-01

    This study aimed to develop a cationic nanosuspension of chitosan (CS) and methoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) for ocular delivery of diclofenac (DIC). MPEG-PCL-CS block polymer was synthesized by covalent coupling of MPEG-PCL with CS. The critical micelle concentration of the MPEG-PCL-CS block polymer was 0.000692 g/L. DIC/MPEG-PCL-CS nanosuspension (mean particle size = 105 nm, zeta potential = 8 mV) was prepared and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry. The nanosuspension was very stable without apparent physical property changes after storage at 4 °C or 25 °C for 20 days, but it was unstable in the aqueous humor solution after 24 h incubation. Sustained release of the encapsulated DIC from the nanosuspension occurred over 8 h. Neither a blank MPEG-PCL-CS nanosuspension nor a 0.1% (mass fraction) DIC/MPEG-PCL-CS nanosuspension caused ocular irritation after 24 h of instillation. Enhanced penetration and retention in corneal tissue was achieved with a Nile red/MPEG-PCL-CS nanosuspension compared with a Nile red aqueous solution. In vivo pharmacokinetics studies showed enhanced pre-corneal retention and penetration of the DIC/MPEG-PCL-CS nanosuspension, which resulted in a higher concentration of DIC (Cmax) in the aqueous humor and better bioavailability compared with commercial DIC eye drops (P < 0.01). PMID:26067670

  1. Reducible poly(2-dimethylaminoethyl methacrylate): synthesis, cytotoxicity, and gene delivery activity.

    PubMed

    You, Ye-Zi; Manickam, Devika Soundara; Zhou, Qing-Hui; Oupický, David

    2007-10-01

    Reducible polycations represent promising carriers of therapeutic nucleic acids. Oligomers of 2-dimethylaminoethyl methacrylate (DMAEMA) containing terminal thiol groups were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization using difunctional chain transfer agent. Reducible poly(DMAEMA) (rPDMAEMA) was synthesized by oxidation of the terminal thiol groups, forming a polymer with disulfide bonds in the backbone. Physico-chemical properties of DNA polyplexes of rPDMAEMA were evaluated by dynamic and static light scattering methods, revealing lower structural density and DNA content than control PDMAEMA polyplexes. Cytotoxicity and transfection activity of rPDMAEMA-based DNA polyplexes were evaluated in vitro. In comparison with control PDMAEMA, only minimum toxic effects of rPDMAEMA were observed in a panel of cell lines. Transfection activity was tested in B16F10 mouse melanoma and six human pancreatic cancer cell lines. rPDMAEMA polyplexes showed a comparable or better activity than control PDMAEMA polyplexes. PMID:17574292

  2. Reducible poly(2-dimethylaminoethyl methacrylate): Synthesis, cytotoxicity, and gene delivery activity

    PubMed Central

    Zhou, Qing-Hui; Oupický, David

    2007-01-01

    Reducible polycations represent promising carriers of therapeutic nucleic acids. Oligomers of 2-dimethylaminoethyl methacrylate (DMAEMA) containing terminal thiol groups were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization using difunctional chain transfer agent. Reducible poly(DMAEMA) (rPDMAEMA) was synthesized by oxidation of the terminal thiol groups, forming a polymer with disulfide bonds in the backbone. Physico-chemical properties of DNA polyplexes of rPDMAEMA were evaluated by dynamic and light scattering methods, revealing lower structural density and DNA content than control PDMAEMA polyplexes. Cytotoxicity and transfection activity of rPDMAEMA-based DNA polyplexes were evaluated in vitro. In comparison with control PDMAEMA, only minimum toxic effects of rPDMAEMA were observed in a panel of cell lines. Transfection activity was tested in B16F10 mouse melanoma and six human pancreatic cancer cell lines. rPDMAEMA polyplexes showed a comparable or better activity than control PDMAEMA polyplexes. PMID:17574292

  3. Improved electrical and optical properties of Poly(3,4-ethylenedioxythiophene) via ordered microstructure

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Li, Yu; Wu, Jun; Noda, Hideki; Fujii, Akihiko; Ozaki, Masanori; Yoshino, Katsumi

    2007-05-01

    Poly(3,4-ethylenedioxythiophene) (PEDOT) nanorods (80-150 nm in diameter) and nanospheres were synthesized through a self-assembly method using ferric chloride (FeCl3) and ammonium persulfate (APS) as oxidants, respectively, and camphorsulfonic acid (CSA) as the dopant. The PEDOT nanorods showed broader absorption bands, higher crystallinity and much higher room-temperature conductivity (approximately 300 S cm-1) than the PEDOT nanospheres. Such obviously distinct properties of these products were considered to be due to the much lower rate of polymerization with FeCl3 than APS, which made the growth of PEDOT according to the suggested cylinder micelles more moderate and regular; as a result, the morphology of the microstructure changed and the crystallinity, the doping level, the molecular orderliness and the conductivity of PEDOT synthesized under lower rate of polymerization improved intensely at the same time.

  4. Characterization of CrO2-poly-vinyl pyrrolidone magnetic nanofluid

    NASA Astrophysics Data System (ADS)

    Singh, D. K.; Pandey, D. K.; Yadav, R. R.; Singh, Devraj

    2012-11-01

    Crystalline CrO2 nanoparticles were synthesized using chemical methods. Nanofluids were synthesized by the dispersion of CrO2 nanoparticles in poly-vinyl pyrrolidone solution by an ultrasonicator. The structural properties of the nanoparticles were studied with the help of X-ray diffraction. The magnetic properties of the powdered CrO2 were measured with a vibrating sample magnetometer. The magneto-resistance and ultrasonic parameters of the nanofluid were characterized. The (a) effect of calcination temperature on crystalinity of CrO2 nanoparticles, (b) influence of sonication time on the nature of the magneto-resistance for the nanofluid, and (c) governing factor/mechanisms responsible to the ultrasonic properties are discussed.

  5. Parallel combinatorial chemical synthesis using single-layer poly(dimethylsiloxane) microfluidic devices

    PubMed Central

    Dexter, Joseph P.; Parker, William

    2009-01-01

    Improving methods for high-throughput combinatorial chemistry has emerged as a major area of research because of the importance of rapidly synthesizing large numbers of chemical compounds for drug discovery and other applications. In this investigation, a novel microfluidic chip for performing parallel combinatorial chemical synthesis was developed. Unlike past microfluidic systems designed for parallel combinatorial chemistry, the chip is a single-layer device made of poly(dimethylsiloxane) that is extremely easy and inexpensive to fabricate. Using the chip, a 2×2 combinatorial series of amide-formation reactions was performed. The results of this combinatorial synthesis indicate that the new device is an effective platform for running parallel organic syntheses at significantly higher throughput than with past methodologies. Additionally, a design algorithm for scaling up the 2×2 combinatorial synthesis chip to address more complex cases was developed. PMID:20216962

  6. Immobilization of poly(ɛ-caprolactone)-poly(ethylene oxide)-poly(ɛ-caprolactone) triblock copolymer on poly(lactide- co-glycolide) surface and dual biofunctional effects

    NASA Astrophysics Data System (ADS)

    Zhu, Aiping; Lu, Ping; Wu, Hao

    2007-01-01

    Poly(ɛ-caprolactone)-poly(ethylene oxide)-poly(ɛ-caprolactone) (PCL-PEG-PCL) triblock copolymer was covalently immobilized onto poly(lactide- co-glycolide) (PLGA) surface with the precursor of photopolymerizable and biodegradable PCL-PEG-PCL diacrylates. Argon plasma technique was exploited to obtain hydrophilic PLGA surface (HPLGA). The surface properties were characterized by Water contact angle and X-ray photoelectron spectroscopy (XPS) techniques. PCL-PEG-PCL surface modified hydrophobic PLGA and hydrophilic PLGA results in different surface physicochemical properties. PCL-PEG-PCL modified hydrophobic PLGA surface (PLGA-PCL-PEG-PCL) demonstrates excellent inhibition of platelet adhesion and activation; while PCL-PEG-PCL modified hydrophilic PLGA surface (HPLGA-PCL-PEG-PCL) results in good cytocompatibility. The possible mechanism was discussed and the driven force was ascribed to the different assembly behavior of PCL-PEG-PCL on PLGA surface dependant on the hydrophilic/hydrophobic property of PLGA. This simple and effective surface engineering method is also suitable for the other biomaterials such as polyurethane (PU), silicon rubber and poly(ethylene terephthalate) (PET) to obtain the enhanced biocompatibility.

  7. Poly(hydroxy acids) in drug delivery.

    PubMed

    Juni, K; Nakano, M

    1987-01-01

    Poly(hydroxy acids) so far have been examined for use in drug delivery in limited number, while the advantageous use of the polymers has been recognized due to their biodegradability and biocompatibility. Homo- and copolymers of lactic acid and glycolic acid have been studied in drug delivery by many workers, while homo- and copolymers of epsilon-caprolactone have been studied by only one group of workers. Although poly-hydroxybutyric acid had been found to be a naturally occurring polymer, examination as to the use of the polymer in drug delivery is rather recent and reports are still limited. In the present article, the use of poly(hydroxy acids) including homo- and copolymers of lactic acid and glycolic acid, polycaprolactone, and poly-beta-hydroxybutyric acid in drug delivery is reviewed. Physicochemical properties, biodegradability, and biocompatibility of the polymers, and evaluations in vitro and in vivo of specific dosage forms using the polymers, are included. The most recent work in our laboratories on the use of polyactic acid and poly-beta-hydroxybutyric acid is also included. PMID:3549007

  8. Biodegradable block poly(ester-urethane)s based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymers.

    PubMed

    Ou, Wenfeng; Qiu, Handi; Chen, Zhifei; Xu, Kaitian

    2011-04-01

    A series of block poly(ester-urethane)s (abbreviated as PU3/4HB) based on biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) segments were synthesized by a facile way of melting polymerization using 1,6-hexamethylene diisocyanate (HDI) as the coupling agent and stannous octanoate (Sn(Oct)(2)) as catalyst, with different 4HB contents and segment lengths. The chemical structure, molecular weight and distribution were systematically characterized by (1)H nuclear magnetic resonance spectrum (NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The thermal property was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hydrophilicity was investigated by static contact angle of deionized water and CH(2)I(2). DSC curves revealed that the PU3/4HB polyurethanes have their T(g) from -25.6 °C to -4.3 °C, and crystallinity from 2.5% to 25.3%, being almost amorphous to semi-crystalline. The obtained PU3/4HBs are hydrophobic (water contact angle 77.4°-95.9°), and their surface free energy (SFE) were studied. The morphology of platelets adhered on the polyurethane film observed by scanning electron microscope (SEM) showed that platelets were activated on the PU3/4HB films which would lead to blood coagulation. The lactate dehydrogenase (LDH) assay revealed that the PU3/4HBs displayed higher platelet adhesion property than raw materials and biodegradable polymer polylactic acid (PLA) and would be potential hemostatic materials. Crystallinity degree, hydrophobicity, surface free energy and urethane linkage content play important roles in affecting the LDH activity and hence the platelet adhesion. CCK-8 assay showed that the PU3/4HB is non-toxic and well for cell growth and proliferation of mouse fibroblast L929. It showed that the hydrophobicity is an important factor for cell growth while 3HB content of the PU3/4HB is important for the cell proliferation. Through changing the

  9. Self-assembled micelles of amphiphilic poly(l-phenylalanine)-b-poly(l-serine) polypeptides for tumor-targeted delivery

    PubMed Central

    Zhao, Ziming; Wang, Yu; Han, Jin; Wang, Keli; Yang, Dan; Yang, Yihua; Du, Qian; Song, Yuanjian; Yin, Xiaoxing

    2014-01-01

    The aim of this work was to design, synthesize, and characterize self-assembled micelles based on polypeptides as a potential antitumor drug carrier. Amphiphilic poly(l-phenylalanine)-b-poly(l-serine) (PFS) polypeptides were obtained through the polymerization of N-carboxyanhydride. As a novel hydrophilic segment, poly(l-serine) was utilized to enhance tumor targeting due to a large demand of tumors for serine. PFS could self-assemble into micelles with an average diameter of 110–240 nm and a slightly negative charge. PFS polypeptides adopted random coil in pH 7.4 phosphate-buffered saline and could partly transform to α-helix induced by trifluoroethanol. PFS micelles with a low critical micelle concentration of 4.0 μg mL−1 were stable in pH 5–9 buffers and serum albumin solution. PFS micelles had a loading capacity of 3.8% for coumarin-6 and exhibited a sustained drug release. Coumarin-6 loaded rhodamine B isothiocyanate-labeled PFS micelles were incubated with Huh-7 tumor cells to study the correlation between drugs and carriers during endocytosis. The uptake of drugs was consistent with the micelles, illustrating that the intracellular transport of drugs highly depended on the micelles. PFS micelles diffused in whole cytoplasm while coumarin-6 assumed localized distribution, suggesting that the micelles could release the loaded drugs in particular areas. The internalization mechanism of PFS micelles was involved with clathrin-mediated endocytosis and macropinocytosis. Excess serine inhibited the uptake of PFS micelles, which demonstrated that serine receptors played a positive role in the internalization of PFS. The more interesting thing was that the uptake inhibition impacted on normal cells but not on tumor cells at the physiological concentration of serine. The difference in the uptake of PFS micelles was fourfold as high between the tumor cells and the normal cells, which indicated that PFS micelles had good tumor targeting in vitro. In conclusion

  10. Green polymer chemistry: Synthesis of poly(disulfide) polymers and networks

    NASA Astrophysics Data System (ADS)

    Rosenthal-Kim, Emily Quinn

    The disulfide group is unique in that it presents a covalent bond that is easily formed and cleaved under certain biological conditions. While the ease of disulfide bond cleavage is often harnessed as a method of biodegradation, the ease of disulfide bond formation as a synthetic strategy is often overlooked. The objective this research was to synthesize poly(disulfide) polymers and disulfide crosslinked networks from a green chemistry approach. The intent of the green chemistry approach was to take advantage of the mild conditions applicable to disulfide bond synthesis from thiols. With anticipated use as biomaterials, it was also desired that the polymer materials could be degraded under biological conditions. Here, a new method of poly(disulfide) polymer synthesis is introduced which was inspired by the reaction conditions and reagents found in Nature. Ambient temperatures and aqueous mixtures were used in the new method. Hydrogen peroxide, one of the Nature's most powerful oxidizing species was used as the oxidant in the new polymerization reaction. The dithiol monomer, 3,6-dioxa-1,8-octanedithiol was first solubilized in triethylamine, which activated the thiol groups and made the monomer water soluble. At room temperature, the organic dithiol/amine solution was then mixed with dilute aqueous hydrogen peroxide (3% by weight) to make the poly(disulfide) polymers. The presence of a two phase system (organic and aqueous phases) was critical to the polymerization reaction. As the reaction progresses, a third, polymer phase appeared. At ambient temperatures and above, this phase separated from the reaction mixture and the polymer product was easily removed from the reaction solution. These polymers reach Mn > 250,000 g/mol in under two hours. Molecular weight distributions were between 1.5 and 2.0. Reactions performed in an ice bath which remain below room temperature contain high molecular weight polymers with Mn ≈ 120,000 g/mol and have a molecular weight

  11. Miscibility and degradability of poly(lactic acid)poly(ethylene oxide)/poly(ethylene glycol) blends

    SciTech Connect

    Yue, C.L.; Dave, V.; Gross, R.A.; McCarthy, S.P.

    1995-12-01

    Poly(lactic acid) [PLA] was melt blended with polyethylene(oxide) [PEG] and poly(ethylene glycol) [PEG] in different compositions to form blown films. It was determined that PLA was miscible with PEO in all compositions. Based on Gordon-Taylor equation, it was determined that the interactions between PLA and PEO is stronger than PEG. The addition of low molecular weight PEG improved the elongation and tear strength of the blends. Enzymatic degradation results shows that the weight loss of all the samples was more than 80% of the initial weight in 48 hours.

  12. Long-term in vivo biostability of poly(dimethylsiloxane)/poly(hexamethylene oxide) mixed macrodiol-based polyurethane elastomers.

    PubMed

    Simmons, Anne; Hyvarinen, Jari; Odell, Ross A; Martin, Darren J; Gunatillake, Pathiraja A; Noble, Kathryn R; Poole-Warren, Laura A

    2004-09-01

    The long-term biostability of a novel thermoplastic polyurethane elastomer (Elast-Eon 2 80A) synthesized using poly(hexamethylene oxide) (PHMO) and poly(dimethylsiloxane) (PDMS) macrodiols has been studied using an in vivo ovine model. The material's biostability was compared with that of three commercially available control materials, Pellethane 2363-80A, Pellethane 2363-55D and Bionate 55D, after subcutaneous implantation of strained compression moulded flat sheet dumbbells in sheep for periods ranging from 3 to 24 months. Scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to assess changes in the surface chemical structure and morphology of the materials. Gel permeation chromatography, differential scanning calorimetry and tensile testing were used to examine changes in bulk characteristics of the materials. The results showed that the biostability of the soft flexible PDMS-based test polyurethane was significantly better than the control material of similar softness, Pellethane 80A, and as good as or better than both of the harder commercially available negative control polyurethanes, Pellethane 55D and Bionate 55D. Changes observed in the surface of the Pellethane materials were consistent with oxidation of the aliphatic polyether soft segment and hydrolysis of the urethane bonds joining hard to soft segment with degradation in Pellethane 80A significantly more severe than that observed in Pellethane 55D. Very minor changes were seen on the surfaces of the Elast-Eon 2 80A and Bionate 55D materials. There was a general trend of molecular weight decreasing with time across all polymers and the molecular weights of all materials decreased at a similar relative rate. The polydispersity ratio, Mw/Mn, increased with time for all materials. Tensile tests indicated that UTS increased in Elast-Eon 2 80A and Bionate 55D following implantation under strained conditions

  13. Facile synthesis of brush poly(phosphoamidate)s via one-pot tandem ring-opening metathesis polymerization and atom transfer radical polymerization.

    PubMed

    Ding, Liang; Qiu, Jun; Wei, Jun; Zhu, Zhenshu

    2014-09-01

    Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA)-based brush poly(phosphoamidate)s are successfully synthesized by a combination of ring-opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP) following either a commutative two-step procedure or a straightforward one-pot process using Grubbs ruthenium-based catalysts for tandem catalysis. Compared with the traditional polymerization method, combining ROMP and ATRP in a one-pot process allows the preparation of brush copolymers characterized by a relatively moderate molecular weight distribution and quantitative conversion of monomer. Moreover, the surface morphologies and aggregation behaviors of these polymers are studied by AFM and TEM measurements. PMID:24729161

  14. Tailoring the degradation kinetics of poly(ester carbonate urethane)urea thermoplastic elastomers for tissue engineering scaffolds.

    PubMed

    Hong, Yi; Guan, Jianjun; Fujimoto, Kazuro L; Hashizume, Ryotaro; Pelinescu, Anca L; Wagner, William R

    2010-05-01

    Biodegradable elastomeric scaffolds are of increasing interest for applications in soft tissue repair and regeneration, particularly in mechanically active settings. The rate at which such a scaffold should degrade for optimal outcomes, however, is not generally known and the ability to select from similar scaffolds that vary in degradation behavior to allow such optimization is limited. Our objective was to synthesize a family of biodegradable polyurethane elastomers where partial substitution of polyester segments with polycarbonate segments in the polymer backbone would lead to slower degradation behavior. Specifically, we synthesized poly(ester carbonate)urethane ureas (PECUUs) using a blended soft segment of poly(caprolactone) (PCL) and poly(1,6-hexamethylene carbonate) (PHC), a 1,4-diisocyanatobutane hard segment and chain extension with putrescine. Soft segment PCL/PHC molar ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 were investigated. Polymer tensile strengths varied from 14 to 34 MPa with breaking strains of 660-875%, initial moduli of 8-24 MPa and 100% recovery after 10% strain. Increased PHC content was associated with softer, more distensible films. Scaffolds produced by salt leaching supported smooth muscle cell adhesion and growth in vitro. PECUU in aqueous buffer in vitro and subcutaneous implants in rats of PECUU scaffolds showed degradation slower than comparable poly(ester urethane)urea and faster than poly(carbonate urethane)urea. These slower degrading thermoplastic polyurethanes provide opportunities to investigate the role of relative degradation rates for mechanically supportive scaffolds in a variety of soft tissue repair and reconstructive procedures. PMID:20188411

  15. The Dielectric Properties of Poly

    NASA Astrophysics Data System (ADS)

    Bello, Alfredo

    The dielectric properties of poly(vinylidene fluoride) (PVF(,2)) are discussed in this work. A review of the literature concerning the five known dielectric relaxations of PVF(,2) is presented and the general theory of dielectric relaxations in polymers is summarized. The real and imaginary parts of the dielectric constant of several samples of PVF(,2) were measured as a function of frequency, temperature and pressure. In the temperature experiment covering the range from 5 K to 380 K at five audio frequencies (100 Hz to 10 KHz), four relaxations were found: (alpha), (beta), (delta) and (epsilon). The (alpha) relaxation at temperatures between 345 and 370 K at 1000 Hz, was found to be dependent on the history and preparation method of the sample and also to have a Debye like behavior. The (beta) relaxation around 250 K at 1000 Hz was found to be related to the glass transition of PVF(,2) and its behavior is parametrized by using the Williams-Landel-Ferry (WLF) model. The (delta) relaxation around 76 K at 1000 Hz was found to be Debye like and associated with the (alpha)-phase of PVF(,2). The (epsilon) relaxation was found in (beta)-phase PVF(,2) at 14.5 K at 1000 Hz. Evidence of the relaxation was found also in (alpha)-phase PVF(,2). In the pressure experiments the (beta) relaxation was studied in the temperature range from 240 to 360 K and at pressures from 0.0001 to 0.6 GPa. The behavior was explained by using the WLF free volume model and comparison between the calculated glass transition temperature parameter in the WLF equation and the experimental peak temperature is made. It was found that even though the WLF equation mathematically describes the (beta) relaxation, the T(,g) parameter does not represent the real transition temperature behavior with pressure. The peak temperature of the (beta) relaxation, was found to be a better guide to the behavior of the real T(,g).

  16. Damage to the protein synthesizing apparatus in mouse liver in vivo by magnetocytolysis in the presence of hepatospecific magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Halbreich, Avraham; Groman, Ernest V.; Raison, Danielle; Bouchaud, Claude; Paturance, Sébastien

    2002-07-01

    In the previous work, we incubated THP1 cells and macrophages in vitro with unsubstituted ferrofluid (FF) and placed them in an alternating magnetic field. This resulted in the destruction of the cells (magnetocytolysis). Cell-specific magnetocytolysis in vitro was achieved in MCF7 human breast cancer cells incubated with tamoxifen-bound FF and treated in an alternating magnetic field. In this work, in a search of a model for magnetocytolysis in vivo, we injected mice intravenously with hepatospecific magnetic nanoparticles (HS-USPIO) and subjected the mice to magnetocytolysis in an alternating magnetic field (1 h at 200 A/m). This treatment resulted in a prolongation of blood coagulation time due to depletion of protein coagulation factors that are synthesized exclusively in the liver. The attendant derangement of liver protein synthesis was characterized in cell-free preparations by an inhibition of the endogenously coded protein synthesis coupled with an enhancement of phenylalanine polymerization directed by polyuridylic acid (Poly U). This indication of polyribosome dispersion was confirmed by electron microscopy. Magnetocytolysis did not cause liver necrosis and was neither accompanied by any increase in body or liver temperature, nor damage to any other tissue. The effects of magnetocytolysis were proportional to the amount of injected HS-USPIO, field strength and its application time. Magnetocytolysis did not occur when non-magnetic PolyGalactoseGold particles were substituted for HS-USPIO. PolyGalactoseGold particles were employed to measure asialoglycoprotein receptor (ASGP-R) activity in liver using neutron activation analysis. Injection of PolyGalactoseGold particles to mice, pre-treated by HS-USPIO driven magnetocytolysis, revealed a transient diminution of hepatic ASGP-R. Liver damage from magnetocytolysis was followed by liver regeneration, manifested by the appearance of thymidylate kinase activity, diminution of ASGP-R and return to normal blood

  17. A study on the combustion characteristics of PVC, poly(styrene), poly(ethylene), and poly(propylene) particles under high heating rates

    SciTech Connect

    Panagiotou, T.; Levendis, Y. . Dept. of Mechanical Engineering)

    1994-10-01

    The combustion characteristics of four commonly encountered plastics: poly(styrene), PVC, poly(ethylene) and poly(propylene) were studied under conditions pertinent to incinerators, that is, high heating rates (in the order of 10,000 K/s) and elevated gas temperatures (1,200--1,500 K). Batches of spherical and monodisperse particles of these plastics were generated in the size range of 53--300 [mu]m. Combustion of single particles, of known size and mass, was conducted in a laminar-flow drop-tube furnace, at controlled atmospheres. The radiation emitted from burning particles was monitored, along their flight path, by simultaneous three-color optical pyrometry and high-speed cinematography. Results indicate that polymer particles (plastics) burned expediently with burntimes similar to those of light oil drops such as kerosene, hexadecane, etc. Both PVC and poly(styrene) burned with very luminous yellow flames, which were attributed to high soot loadings. The flame combustion of PVC was the brightest and fastest with steadily decreasing temperature and flame diameter, while that of poly(styrene) occurred mostly at constant flame diameter and mildly decreasing temperature. Combustion of both poly(ethylene) and poly(propylene) was dimmer and somewhat lengthier. Furthermore, in this temperature region, it is argued herein that the combustion of poly(styrene), poly(ethylene), and poly(propylene) occurred concurrently with, and was partially controlled by, pyrolysis reactions. PVC seemed to undergo significant pyrolysis prior to ignition; thereafter, combustion occurred in a premixed-like flame mode and, finally, dimly glowing combustion of the remaining char was observed. PVC exhibited the highest soot volume fraction in its flame, followed by poly(styrene); poly(propylene), and poly(ethylene). Moreover, it was observed that the rate of burning was the highest for PVC particles and the lowest for poly(ethylene).

  18. Syntheses of dopa glycosides using glucosidases.

    PubMed

    Sivakumar, Ramaiah; Ponrasu, Thangavel; Divakar, Soundar

    2009-02-01

    Syntheses of L: -dopa 1a glucoside 10a,b and DL: -dopa 1b glycosides 10-18 with D: -glucose 2, D: -galactose 3, D: -mannose 4, D: -fructose 5, D: -arabinose 6, lactose 7, D: -sorbitol 8 and D: -mannitol 9 were carried out using amyloglucosidase from Rhizopus mold, beta-glucosidase isolated from sweet almond and immobilized beta-glucosidase. Invariably, L: -dopa and DL: -dopa gave low to good yields of glycosides 10-18 at 12-49% range and only mono glycosylated products were detected through glycosylation/arylation at the third or fourth OH positions of L: -dopa 1a and DL: -dopa 1b. Amyloglucosidase showed selectivity with D: -mannose 4 to give 4-O-C1beta and D: -sorbitol 8 to give 4-O-C6-O-arylated product. beta-Glucosidase exhibited selectivity with D: -mannose 4 to give 4-O-C1beta and lactose 7 to give 4-O-C1beta product. Immobilized beta-glucosidase did not show any selectivity. Antioxidant and angiotensin converting enzyme inhibition (ACE) activities of the glycosides were evaluated glycosides, out of which L: -3-hydroxy-4-O-(beta-D: -galactopyranosyl-(1'-->4)beta-D: -glucopyranosyl) phenylalanine 16 at 0.9 +/- 0.05 mM and DL: -3-hydroxy-4-O-(beta-D: -glucopyranosyl) phenylalanine 11b,c at 0.98 +/- 0.05 mM showed the best IC(50) values for antioxidant activity and DL: -3-hydroxy-4-O-(6-D: -sorbitol)phenylalanine 17 at 0.56 +/- 0.03 mM, L: -dopa-D: -glucoside 10a,b at 1.1 +/- 0.06 mM and DL: -3-hydroxy-4-O-(D: -glucopyranosyl)phenylalanine 11a-d at 1.2 +/- 0.06 mM exhibited the best IC(50) values for ACE inhibition. PMID:18712474

  19. Syntheses and electronic structures of decamethylmetallocenes

    SciTech Connect

    Robbins, J.L.

    1981-04-01

    The synthesis of decamethylmanganocene ((eta-C/sub 5/(CH/sub 3/)/sub 5/)/sub 2/Mn or (Me/sub 5/Cp)/sub 2/Mn)) is described. Magnetic susceptibility and electron paramagnetic resonance (EPR) studies show that (Me/sub 5/Cp)/sub 2/Mn is a low-spin, 17-electron compound with an orbitally degenerate, /sup 2/E/sub 2g/ (e/sub 2g//sup 3/ a/sub 1g//sup 2/) ground state. An x-ray crystallographic study of (Me/sub 5/Cp)/sub 2/Mn shows that it is a monomeric, D/sub 5d/ decamethylmetallocene with metal to ring carbon distances that are about 0.3 A shorter than those determined for high-spin manganocenes. The syntheses of new (Me/sub 5/Cp)/sub 2/M (M = Mg,V,Cr,Co, and Ni) and ((Me/sub 5/Cp)/sub 2/M)PF/sub 6/ (M = Cr,Co, and Ni) compounds are described. In addition, a preparative route to a novel, dicationic decamethylmetallocene, ((Me/sub 5/Cp)/sub 2/Ni)(PF/sub 6/)/sub 2/ is reported. Infrared, nuclear magnetic resonance, magnetic susceptibility, and/or x-ray crystallographic studies indicate that all the above compounds are D/sub 5d/ or D/sub 5h/ decamethylmetallocenes with low-spin electronic configurations. Cyclic voltammetry studies verify the reversibility and the one-electron nature of the (Me/sub 5/Cp)/sub 2/M ..-->.. ((Me/sub 5/Cp)/sub 2/M)/sup +/ (M = Cr,Mn,Fe,Co,Ni), ((Me/sub 5/Cp)/sub 2/Mn)/sup -/ ..-->.. (Me/sub 5/Cp)/sub 2/Mn and ((Me/sub 5/Cp)/sub 2/Ni)/sup +/ ..-->.. (Me/sub 5/Cp)/sub 2/Ni)/sup 2 +/ redox reactions. These studies reveal that the neutral decamethylmetallocenes are much more easily oxidized than their metallocene counterparts. This result attests to the electron-donating properties of the ten substituent methyl groups. Proton and carbon-13 NMR data are reported for the diamagnetic Mg(II), Mn(I), Fe(II), Co(III), and Ni(IV) decamethylmetallocenes and for ((Me/sub 5/Cp)/sub 2/V(CO)/sub 2/)/sup +/. The uv-visible absorption spectra of the 15-, 18- and 20- electron decamethylmetallocenes are also reported.

  20. Voltammetric studies of poly(carbon disulfide)

    SciTech Connect

    Geng, L.; Xu, J.; Prasad, S.; Skotheim, T.A.; Lee, H.S.; McBreen, J.

    1992-12-31

    Poly(carbon disulfide) was studied by cyclic voltammetry using glassy carbon and platinum macro- and microdisk electrodes. The electron transfer kinetics is significantly faster at glassy carbon electrodes than at Pt electrodes. It is chemically reversible with moderate electron transfer rates. Voltammetric results of poly(carbon disulfide) are in good agreement with battery testing data. The k{sup 0} value measured at a Pt microdisk electrode is 7{times}10{sup 3} cm/sec. Electrochemical data suggest that PCS can be a potential cathode material for low current density lithium batteries.

  1. Precision frequency synthesizing sources with excellent time/frequency performances

    NASA Technical Reports Server (NTRS)

    Zhou, Liren; Lin, Hai

    1994-01-01

    Precision frequency synthesizing sources are needed in the time / frequency measuring system, atomic frequency standards, telemetry, communication, and radar systems. This kind of frequency synthesizing source possesses high frequency accuracy and excellent long term and short term frequency stability. Several precision frequency synthesizing sources developed by Beijing Institute of Radio Metrology and Measurement (BIRMM) which have been successfully applied to the time / frequency measuring system, atomic frequency standards system, and radar system are described. In addition, the working principle, implementation approach, and the main technical specifications of the frequency synthesizing sources are also given.

  2. VERO cells harbor a poly-ADP-ribose belt partnering their epithelial adhesion belt

    PubMed Central

    Vilchez Larrea, Salomé C.; Kun, Alejandra

    2014-01-01

    Poly-ADP-ribose (PAR) is a polymer of up to 400 ADP-ribose units synthesized by poly-ADP-ribose-polymerases (PARPs) and degraded by poly-ADP-ribose-glycohydrolase (PARG). Nuclear PAR modulates chromatin compaction, affecting nuclear functions (gene expression, DNA repair). Diverse defined PARP cytoplasmic allocation patterns contrast with the yet still imprecise PAR distribution and still unclear functions. Based on previous evidence from other models, we hypothesized that PAR could be present in epithelial cells where cadherin-based adherens junctions are linked with the actin cytoskeleton (constituting the adhesion belt). In the present work, we have examined through immunofluorescence and confocal microscopy, the subcellular localization of PAR in an epithelial monkey kidney cell line (VERO). PAR was distinguished colocalizing with actin and vinculin in the epithelial belt, a location that has not been previously reported. Actin filaments disruption with cytochalasin D was paralleled by PAR belt disruption. Conversely, PARP inhibitors 3-aminobenzamide, PJ34 or XAV 939, affected PAR belt synthesis, actin distribution, cell shape and adhesion. Extracellular calcium chelation displayed similar effects. Our results demonstrate the existence of PAR in a novel subcellular localization. An initial interpretation of all the available evidence points towards TNKS-1 as the most probable PAR belt architect, although TNKS-2 involvement cannot be discarded. Forthcoming research will test this hypothesis as well as explore the existence of the PAR belt in other epithelial cells and deepen into its functional implications. PMID:25332845

  3. A Low Protein Binding Cationic Poly(2-oxazoline) as Non-Viral Vector

    PubMed Central

    He, Zhijian; Miao, Lei; Jordan, Rainer; S-Manickam, Devika; Luxenhofer, Robert; Kabanov, Alexander V

    2015-01-01

    Developing safe and efficient non-viral gene delivery systems remains a major challenge. We present a new cationic poly(2-oxazoline) (CPOx) block copolymer for gene therapy that was synthesized by sequential polymerization of non-ionic 2-methyl-2-oxazoline and a new 2-oxazoline monomer, 2-(N-methyl, N-Boc-amino)-methyl-2-oxazoline, followed by deprotection of the pendant secondary amine groups. Upon mixing with plasmid DNA (pDNA), CPOx forms small (diameter ≈ 80 nm) and narrowly dispersed polyplexes (PDI < 0.2), which are stable upon dilution in saline and against thermal challenge. These polyplexes exhibited low plasma protein binding and very low cytotoxicity in vitro compared to the polyplexes of pDNA and poly(ethylene glycol)-b-poly(l-lysine) (PEG-b-PLL). CPOx/pDNA polyplexes at N/P = 5 bound considerably less plasma protein compared to polyplexes of PEG-b-PLL at the same N/P ratio. This is a unique aspect of the developed polyplexes emphasizing their potential for systemic delivery in vivo. The transfection efficiency of the polyplexes in B16 murine melanoma cells was low after 4 h but increased significantly for 10 h exposure time, indicative of slow internalization of polyplexes. Addition of Pluronic P85 boosted the transfection using CPOx/pDNA polyplexes considerably. The low protein binding of CPOx/pDNA polyplexes is particularly interesting for the future development of targeted gene delivery. PMID:25846127

  4. Synthesis of Poly Linear shRNA Expression Cassettes Through Branch-PCR.

    PubMed

    Liu, Jianbing; Xi, Zhen

    2016-01-01

    A facile and universal strategy to construct the poly linear small hairpin RNA (shRNA) expression cassettes with multiple shRNA transcription templates through polymerase chain reaction with flexible branched primers (branch-PCR) is described in this protocol. Double-stranded RNA (dsRNA) is not stable enough for the study of RNA interference (RNAi) delivery in mammalian cells. Therefore, the more stable shRNA transcription template is employed to produce the endogenous transcribed dsRNA. Then, the covalent crosslinked linear shRNA expression cassettes are constructed through the branch-PCR for the long-lasting RNAi effect in this protocol. The branched primer pair is efficiently synthesized through classic click chemistry. In one step of PCR, the much more stable poly linear shRNA expression cassettes can be produced in large scale. This strategy of efficient synthesis of the poly linear gene expression cassettes can also be applied in the field for other target gene delivery. © 2016 by John Wiley & Sons, Inc. PMID:27584702

  5. Does inhibition of poly(ADP-ribose) polymerase prevent energy overconsumption under microgravity?

    NASA Astrophysics Data System (ADS)

    Dobrota, C.; Piso, M. I.; Keul, A.

    When plants are exposed to a stress signal they expend a lot of energy and exhibit enhanced respiration rates This is partially due to a breakdown in the NAD pool caused by the enhanced activity PARP which uses NAD as a substrate to synthesize polymers of ADP-ribose Stress-induced depletion of NAD results in a similar depletion of energy since ATP molecules are required to resynthesize the depleted NAD It seems that plants with lowered poly ADP ribosyl ation activity appear tolerant to multiple stresses Inhibiting PARP activity prevents energy overconsumption under stress allowing normal mitochondrial respiration We intend to study if the microgravity is perceived by plants as a stress factor and if experimental inhibition of poly ADP-ribose polymerase may improve the energetic level of the cells References DeBlock M Verduyn C De Brouwer D and Cornelissen M 2005 Poly ADP-ribose polymerase in plants affects energy homeostasis cell death and stress tolerance The Plant Journal 41 95--106 Huang S Greenway H Colmerm T D and Millar A H 2005 Protein synthesis by rice coleoptiles during prolonged anoxia Implications for glycolysis growth and energy utilization Annals of Botany 96 703--715 Mittler R Vanderauwera S Gollery M and Van Breusegem F 2005 Reactive oxygen gene network of plants Trends in Plant Science 9 10 490-498

  6. Carbon nanotubes with small and tunable diameters from poly(ferrocenylsilane)-block-polysiloxane diblock copolymers.

    PubMed

    Lu, Jennifer Q; Rider, David A; Onyegam, Emanuel; Wang, Hai; Winnik, Mitchell A; Manners, Ian; Cheng, Qian; Fu, Qiang; Liu, Jie

    2006-05-23

    Iron-containing nanostructures produced from various self-assembled poly(ferrocenylsilane)-block-polysiloxane thin films are catalytically active for the initiation and growth of high density, small diameter carbon nanotubes (CNTs). Moreover, the tube diameter and density can be tuned by adjusting the chain lengths of the block copolymer. Iron-containing nanostructures from poly(ferrocenylmethylethylsilane)-b-poly(methylvinylsiloxane) polymer with 25 repeat units of an iron-containing segment and 265 repeat units of a non-iron-containing segment are able to produce CNTs with diameters around or less than 1 nm. Lithographically selective growth of CNTs across a large surface area has been demonstrated using this polymer system. Under the same growth condition, it has been found that the yield of defect-free CNTs varies with the size of the catalytically active nanostructures, which are dictated by the chain lengths of the two blocks. This result indicates that, for a specific-sized catalyst nanocluster, a unique set of growth conditions is required for synthesizing high yield, defect-free CNTs. This finding further addresses the importance of using uniform-sized catalyst-containing nanostructures for consistently achieving high-yield and high-quality CNTs with a minimum number of defects and amount of amorphous carbon. PMID:16700610

  7. Pt silicide/poly-Si Schottky diodes as temperature sensors for bolometers

    SciTech Connect

    Yuryev, V. A. Chizh, K. V.; Chapnin, V. A.; Mironov, S. A.; Dubkov, V. P.; Uvarov, O. V.; Kalinushkin, V. P.; Senkov, V. M.; Nalivaiko, O. Y.; Novikau, A. G.; Gaiduk, P. I.

    2015-05-28

    Platinum silicide Schottky diodes formed on films of polycrystalline Si doped by phosphorus are demonstrated to be efficient and manufacturable CMOS-compatible temperature sensors for microbolometer detectors of radiation. Thin-film platinum silicide/poly-Si diodes have been produced by a CMOS-compatible process on artificial Si{sub 3}N{sub 4}/SiO{sub 2}/Si(001) substrates simulating the bolometer cells. Layer structure and phase composition of the original Pt/poly-Si films and the Pt silicide/poly-Si films synthesized by a low-temperature process have been studied by means of the scanning transmission electron microscopy; they have also been explored by means of the two-wavelength X-ray structural phase analysis and the X-ray photoelectron spectroscopy. Temperature coefficient of voltage for the forward current of a single diode is shown to reach the value of about −2%/ °C in the temperature interval from 25 to 50 °C.

  8. From Waste to Plastic: Synthesis of Poly(3-Hydroxypropionate) in Shimwellia blattae

    PubMed Central

    Heinrich, Daniel; Andreessen, Björn; Madkour, Mohamed H.; Al-Ghamdi, Mansour A.; Shabbaj, Ibrahim I.

    2013-01-01

    In recent years, glycerol has become an attractive carbon source for microbial processes, as it accumulates massively as a by-product of biodiesel production, also resulting in a decline of its price. A potential use of glycerol in biotechnology is the synthesis of poly(3-hydroxypropionate) [poly(3HP)], a biopolymer with promising properties which is not synthesized by any known wild-type organism. In this study, the genes for 1,3-propanediol dehydrogenase (dhaT) and aldehyde dehydrogenase (aldD) of Pseudomonas putida KT2442, propionate-coenzyme A (propionate-CoA) transferase (pct) of Clostridium propionicum X2, and polyhydroxyalkanoate (PHA) synthase (phaC1) of Ralstonia eutropha H16 were cloned and expressed in the 1,3-propanediol producer Shimwellia blattae. In a two-step cultivation process, recombinant S. blattae cells accumulated up to 9.8% ± 0.4% (wt/wt [cell dry weight]) poly(3HP) with glycerol as the sole carbon source. Furthermore, the engineered strain tolerated the application of crude glycerol derived from biodiesel production, yielding a cell density of 4.05 g cell dry weight/liter in a 2-liter fed-batch fermentation process. PMID:23542629

  9. Poly(aspartic acid) (PAA) hydrolases and PAA biodegradation: current knowledge and impact on applications.

    PubMed

    Hiraishi, Tomohiro

    2016-02-01

    Thermally synthesized poly(aspartic acid) (tPAA) is a bio-based, biocompatible, biodegradable, and water-soluble polymer that has a high proportion of β-Asp units and equivalent moles of D- and L-Asp units. Poly(aspartic acid) (PAA) hydrolase-1 and hydrolase-2 are tPAA biodegradation enzymes purified from Gram-negative bacteria. PAA hydrolase-1 selectively cleaves amide bonds between β-Asp units via an endo-type process, whereas PAA hydrolase-2 catalyzes the exo-type hydrolysis of the products of tPAA hydrolysis by PAA hydrolase-1. The novel reactivity of PAA hydrolase-1 makes it a good candidate for a biocatalyst in β-peptide synthesis. This mini-review gives an overview of PAA hydrolases with emphasis on their biochemical and functional properties, in particular, PAA hydrolase-1. Functionally related enzymes, such as poly(R-3-hydroxybutyrate) depolymerases and β-aminopeptidases, are compared to PAA hydrolases. This mini-review also provides findings that offer an insight into the catalytic mechanisms of PAA hydrolase-1 from Pedobacter sp. KP-2. PMID:26695157

  10. Thermal responsive hydrogels based on semi interpenetrating network of poly(NIPAm) and cellulose nanowhiskers.

    PubMed

    Hebeish, A; Farag, S; Sharaf, S; Shaheen, Th I

    2014-02-15

    A hybrid hydrogel nanocomposite was developed based on semi interpenetrating network that was formed as a result of concurrent free radical polymerization of N-isopropylacrylamide (NIPAm) and methylenebis acrylamide (MBA) crosslinker along with cellulose nanowhiskers (CNWs). CNWs were synthesized through sulfuric acid hydrolysis and used in preparation of semi interpenetrating network (IPN). CNWs have considered as reinforcement materials for poly(NIPAm) because CNWs were distributed as strengthening entities in Poly(NIPAm). N-isopropylacrylamide was polymerized in presence of methylenebis acrylamide crosslinking agent using K2S2O8 as initiator at 700 C for 1h. The resulting hydrogel's structure, morphology, thermal sensitive property and swelling behavior were investigated. It was found that introducing CNWs into Poly(NIPAm) causes a huge increase in the value of equilibrium swelling ratio (ESR) as compared with the pure PNIPAm. The ESR ranges from 21.6g/g to 5 g/g as the swelling temperature changes from 310 °C to 340 °C; hence, the hydrogel exhibits a good responsive temperature at about 320 °C. PMID:24507268

  11. Multi-technique characterization of poly-L-lysine dendrigrafts-Cu(II) complexes for biocatalysis.

    PubMed

    Rossi, Jean-Christophe; Maret, Barbara; Vidot, Kevin; Francoia, Jean-Patrick; Cangiotti, Michela; Lucchi, Susanna; Coppola, Concetta; Ottaviani, Maria Francesca

    2015-02-01

    Poly-L-lysine is a biocompatible polymer used for drug or gene delivery, for transport through cellular membranes, and as nanosized magnetic resonance imaging contrast agents. Cu(II)-poly-L-lysine complexes are of particular interest for their role in biocatalysis. In this study, poly-L-lysine dendrigrafts (DGLs) at different generations (G2, G3, and G4) are synthesized and characterized in absence and presence of Cu(II) by means of electron paramagnetic resonance (EPR), UV-Vis, potentiometric titration and circular dichroism (CD). The analysis is performed as a function of the [Cu(II)]/[Lys] (=R) molar ratio, pH and generation by identifying differently flexible complexes in different dendrimer regions. The amine sites in the lateral chains become increasingly involved with the increase of pH. The good agreement and complementarity of the results from the different techniques provide an integrate view of the structural and dynamic properties of Cu(II)-DGL complexes implementing their use as biocatalysts. PMID:25330467

  12. Pt silicide/poly-Si Schottky diodes as temperature sensors for bolometers

    NASA Astrophysics Data System (ADS)

    Yuryev, V. A.; Chizh, K. V.; Chapnin, V. A.; Mironov, S. A.; Dubkov, V. P.; Uvarov, O. V.; Kalinushkin, V. P.; Senkov, V. M.; Nalivaiko, O. Y.; Novikau, A. G.; Gaiduk, P. I.

    2015-05-01

    Platinum silicide Schottky diodes formed on films of polycrystalline Si doped by phosphorus are demonstrated to be efficient and manufacturable CMOS-compatible temperature sensors for microbolometer detectors of radiation. Thin-film platinum silicide/poly-Si diodes have been produced by a CMOS-compatible process on artificial Si3N4/SiO2/Si(001) substrates simulating the bolometer cells. Layer structure and phase composition of the original Pt/poly-Si films and the Pt silicide/poly-Si films synthesized by a low-temperature process have been studied by means of the scanning transmission electron microscopy; they have also been explored by means of the two-wavelength X-ray structural phase analysis and the X-ray photoelectron spectroscopy. Temperature coefficient of voltage for the forward current of a single diode is shown to reach the value of about -2%/ °C in the temperature interval from 25 to 50 °C.

  13. Poly(U) RNA-templated synthesis of AppA

    PubMed Central

    Puthenvedu, Deepa; Janas, Teresa; Majerfeld, Irene; Illangasekare, Mali; Yarus, Michael

    2015-01-01

    Simple nucleotide templating activities are of interest as potential primordial reactions. Here we describe the acceleration of 5′-5′ AppA synthesis by 3′-5′ poly(U) under normal solution conditions. This reaction is apparently templated via complementary U:A base-pairing, despite the involvement of two different RNA backbones, because poly(U), unlike other polymers, significantly stimulates AppA synthesis. These interactions occur in moderate (K+) and (Mg2+) and are temperature sensitive, being more efficient at 10°C than at 4°C, but absent at 20°C. The reaction is only slightly pH sensitive, despite potentially relevant substrate pKa’s. Kinetic data explicitly support production of AppA by interaction of stacked 2MeImpA and pA nucleotides paired with a single molecule of U template. At a lower rate, AppA can also be produced by a chemical reaction between 2MeImpA and pA, without participation of poly(U). Molecular modeling suggests that 5′-5′ joining between stacked or concurrently paired A's can occur without major departures from normal U-A helical coordinates. So, coenzyme-like 5′-5′ purine dinucleotides might be readily synthesized from 3′-5′ RNAs with complementary sequences. PMID:26272215

  14. Study on Cluster Formation of Poly 2-HYDROXYETHYL Methacrylate Functionalized Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Ashok Kumar, Nanjundan; Kim, Sung Hun; Kim, Jong Tae; Lim, Kwon Taek; Jeong, Yeon Tae

    Cluster-like network structures of single-walled carbon nanotubes (SWNTs) were synthesized by chemical grafting poly 2-hydroxyethyl methacrylate (polyHEMA) to the sidewalls of SWNTs. Acid chloride-functionalized tubes were coupled with commercially available HEMA monomer, which was in turn polymerized using a radical initiator. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to identify the surface changes on the nanocomposites. Microscopic observations of the nanotube complexes by field emission scanning electron microscopy (FE-SEM) show that the tubes were dispersed and formed cluster-like network, branched structures with less bundling, thus, strongly suggesting a firm coating of the polymer on nanotube walls. The coating was further confirmed by transmission electron microscopy. The thermal properties of the nanotube complex as studied by thermal gravimetric analysis (TGA) revealed that coating enhanced stability of the complex, when compared to that of bulk polyHEMA and pristine SWNTs. The nanotube complexes showed excellent suspension stability when dispersed in organic solvent.

  15. Morphologies of ABC Triblock Terpolymer Melts Containing Poly(Cyclohexadiene): Effects of Conformational Asymmetry

    SciTech Connect

    Kumar, Rajeev; Sides, Scott W.; Goswami, Monojoy; Sumpter, Bobby G.; Hong, Kunlun; Wu, Xiaodong; Russell, Thomas P.; Gido, Samuel P.; Misichronis, Konstantinos; Rangou, Sofia; Avgeropoulos, Apostolos; Tsoukatos, Thodoris; Hadjichristidis, Nikos; Beyer, Frederick L.; Mays, Jimmy W.

    2013-02-12

    We have synthesized linear ABC triblock terpolymers containing poly(1,3-cyclohexadiene), PCHD, as an end block and characterized their morphologies in the melt. Specifically, we have studied terpolymers containing polystyrene (PS), polybutadiene (PB), and polyisoprene (PI) as the other blocks. Systematically varying the ratio of 1,2- /1,4-microstructures of poly(1,3-cyclohexadiene), we have studied the effects of conformational asymmetry among the three blocks on the morphologies using transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and self-consistent field theory (SCFT) performed with PolySwift++. Our work reveals that the triblock terpolymer melts containing a high percentage of 1,2-microstructures in the PCHD block are disordered at 110 °C for all the samples, independent of sequence and volume fraction of the blocks. In contrast, the triblock terpolymer melts containing a high percentage of 1,4-microstructure form regular morphologies known from the literature. The accuracy of the SCFT calculations depends on calculating the χ parameters that quantify the repulsive interactions between different monomers. Simulations using χ values obtained from solubility parameters and group contribution methods are unable to reproduce the morphologies as seen in the experiments. However, SCFT calculations accounting for the enhancement of the χ parameter with an increase in the conformational asymmetry lead to an excellent agreement between theory and experiments. These results highlight the importance of conformational asymmetry in tuning the χ parameter and, in turn, morphologies in block copolymers.

  16. Synthesis and Properties of Poly[p-(2,5-dihydroxy)-phenylenebenzobisoxazole] Fiber

    PubMed Central

    Lin, Hong; Huang, Yu-Dong; Wang, Feng

    2008-01-01

    The novel polymer poly[p-(2,5-dihydroxy)-phenylenebenzobisoxazole] (PBOH) fiber was synthesized in the presence of 2,5-dihydroxyterephthalicacid (DHTA) and 4,6-diamino-1,3-benzenediol in poly(phosphoric acid) (PPA) using typical polycondensation conditions. The crystalline solutions of liquid PBOH in PPA were spun into fibers using dry-jet wet spinning. Furthermore, the thermostability and mechanical properties of PBOH were compared with poly(p-phenylene-2,6-benzoxazole) (PBO) in order to investigate the relationship between the chain structure and properties. The results indicated that the thermal degradation temperature of PBOH was above 750K and the tensile strength of the PBOH fiber was 3.1GPa, which were much lower than those of PBO fiber. The compressive strength of PBOH fiber was 331 M Pa, which was slightly higher than that of PBO fiber. In addition, molecular simulation was employed to explain why the compressive strength of PBOH fiber did not increase significantly compared to PBO fiber. PMID:19330065

  17. Transgene Delivery using Poly(amino ether)-Gold Nanorod Assemblies

    PubMed Central

    Ramos, James; Rege, Kaushal

    2012-01-01

    Gold nanorods (GNRs) have emerged as promising nanomaterials for biosensing, imaging, photothermal treatment and therapeutic delivery for several diseases, including cancer. We have generated poly(amino ether)-functionalized gold nanorods (PAE-GNRs) using a layer-by-layer deposition approach; polymers from a poly(amino ether) library recently synthesized in our laboratory were employed to generate the PAE-GNR assemblies. PAE-GNR assemblies demonstrate long-term colloidal stability as well as the capacity to bind plasmid DNA by means of electrostatic interactions. Sub-toxic concentrations of PAE-GNRs were employed to deliver plasmid DNA to prostate cancer cells in vitro. PAE-GNRs generated using 1,4C-1,4Bis, a cationic polymer from our laboratory demonstrated significantly higher transgene expression and exhibited lower cytotoxicities when compared to similar assemblies generated using 25 kDa poly(ethylene imine) (PEI25k-GNRs), a current standard for polymer-mediated gene delivery. The roles of polyelectrolyte chemistry and zeta-potential in determining transgene expression efficacies of PAE-GNR assemblies were investigated. Our results indicate that stable and effective PAE-GNR assemblies are a promising engineered platform for transgene delivery. PAE-GNRs also have the potential to be used simultaneously for photothermal ablation, photothermally enhanced drug and gene delivery, and biological imaging, thus making them a powerful theranostic platform. PMID:22170455

  18. Novel stimuli responsive gellan gum-graft-poly(DMAEMA) hydrogel as adsorbent for anionic dye.

    PubMed

    Karthika, J S; Vishalakshi, B

    2015-11-01

    In this study, gellan gum-grafted-poly((2-dimethylamino) ethyl methacrylate) (GG-g-poly(DMAEMA)) hydrogel was made by free radical polymerization in aqueous media employing microwave irradiation technique. Ammonium persulfate (APS)/N,N,N',N'-tetramethylethylenediamine (TMEDA) were used as initiator-accelerator pair. N,N'-methylenebisacrylamide (MBA) has been used as crosslinker. The gel was characterized by FTIR, XRD, TGA, DSC and SEM techniques. The characteristic peaks at 1724, 2630, 1147, 1650 and 1535cm(-1) in the IR spectrum confirms grafting and gel formation. The TGA data reveals that synthesized gels were thermally more stable than gellan gum. The XRD studies confirm the crystalline nature of the synthesized material. Swelling behaviour of the hydrogel under different temperatures and pH conditions was investigated. The results indicated drastic changes in swelling around pH 7.0 and 50°C. The gels were evaluated as an adsorbent to remove an anionic dye, methyl orange (MO), from aqueous solution. The pH conditions for maximum adsorption were optimized, the adsorption data is observed to fit best to the Freundlich isotherm model and the maximum adsorption capacity was found to be 25.8mgg(-1). The kinetic analysis revealed a second-order adsorption process. The thermodynamic parameters showed the adsorption to be exothermic and non-spontaneous at high temperatures. PMID:26325677

  19. Synthesis and characterization of carboxymethyl xylan-g-poly(propylene oxide) and its application in films.

    PubMed

    Peng, Pai; Zhai, Meizhi; She, Diao; Gao, Yuefang

    2015-11-20

    Carboxymethyl xylan-g-poly(propylene oxide) (CMX-g-PPO) was successfully synthesized by grafting poly(propylene oxide) chains onto xylan from bamboo using the Al(Oi-Pr)3 initiated ring-opening polymerization of propylene oxides, followed by carboxymethylation with sodium chloroacetate under microwave irradiation. The synthesized CMX-g-PPO was well characterized by FT-IR, (13)C NMR, and AFM. The AFM imaging showed that the average sizes of xylan were 422.1×67.4×1.2nm, while the average sizes of grafting branches PPO were 128.0×38.5×5.1nm, which firstly provided an irrefutable and visual evidence for the structure of grafted xylan at single molecular level. Subsequently, a serial of CMX-g-PPO/CS films were prepared without addition of any plasticizers. The surface morphologies, wettability, water vapor barrier properties, mechanical properties, and thermal stabilities of the obtained films were characterized and compared with those of the control films by AFM, contact angle, WVP, tensile testing, and TGA, respectively. PMID:26344263

  20. Sulfonated poly(ether sulfone)s containing pyridine moiety for PEMFC.

    PubMed

    Jang, Hohyoun; Islam, Md Monirul; Lim, Youngdon; Hossain, Md Awlad; Cho, Younggil; Joo, Hyunho; Kim, Whangi; Jeon, Heung-Seok

    2014-10-01

    Sulfonated poly(ether sulfone)s with varied degree of sulfonation (DS) were prepared via post-sulfonation of synthesized pyridine based poly(ether sulfone) (PPES) using concentrated sulfuric acid as sulfonating agent. The DS was varied with different mole ratio of 4,4'-(2,2-diphenylethenylidene)diphenol, DHTPE in the polymer unit. PPES copolymers were synthesized by direct polycondensation of pyridine unit with bis-(4-fluorophenyl)-sulfone, 4, 4'-sulfonyldiphenol and DHTPE. The structure of the resulting PPES copolymer membranes with different sulfonated units were studied by 1H NMR spectroscopy and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymer with water. The ion exchange capacity (IEC) and proton conductivity were evaluated according to the increase of DS. The water uptake (WU) of the resulting membranes was in the range of 17-58%, compared to that of Nafion 211 28%. The membranes provided proton conductivities of 65-95 mS/cm in contrast to 103 mS/cm of Nafion 211. PMID:25942869

  1. Synthesis, Characterization and Application of Thermoresponsive Polyhydroxyalkanoate-graft-Poly(N-isopropylacrylamide).

    PubMed

    Ma, Yi-Ming; Wei, Dai-Xu; Yao, Hui; Wu, Lin-Ping; Chen, Guo-Qiang

    2016-08-01

    A thermoresponsive graft copolymer polyhydroxyalkanoate-g-poly(N-isopropylacrylamide) or short as PHA-g-PNIPAm, was successfully synthesized via a three-step reaction. First, PNIPAm oligomer with a trithiocarbonate-based chain transfer agent (CTA), short as PNIPAm-CTA, with designed polymerization degree was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Subsequently, the PNIPAm-CTA was treated with n-butylamine for aminolysis in order to obtain a pendant thiol group at the end of the chain (PNIPAm-SH). Finally, the PNIPAm-SH was grafted onto unsaturated P(3HDD-co-3H10U), a random copolymer of 3-hydroxydodecanoate (3HDD) and 3-hydroxy-10-undecylenate (3H10U), via a thiol-ene click reaction. Enhanced hydrophilicity and thermoresponsive property of the resulted PHA-g-PNIPAm were confirmed by water contact angle studies. The biocompatibility of PHA-g-PNIPAm was comparable to poly-3-hydroxybutyrate (PHB). The graft copolymer PHA-g-PNIPAm based on biopolyester PHA could be a promising material for biomedical applications. PMID:27350125

  2. Functional end-capped conducting poly (3,4-ethylenedioxythiophene)

    NASA Astrophysics Data System (ADS)

    Sabatini, V.; Farina, H.; Ortenzi, Marco A.

    2016-05-01

    Methacrylate-terminated Poly(3,4-Ethylenedioxythiophene) (PEDOT) polymers with controlled degree of polymerization were successfully prepared by direct oxidative polycondensation between Ethylenedioxythiophene (EDOT) and a cross-linkable methacrylate end-capper monomer, obtained via Friedel Crafts acylation starting from EDOT and Methacryloyl chloride. The new polymer was synthesized in order to overcome the well-known technical problems of PEDOT, i.e. difficult processability and patterning, due to its poor solubility in common organic and inorganic solvents. The chemical structure and the degree of polymerization of the end-capped polymers were determined by 1H NMR spectra. A new synthesis of Methacrylate end-capped PEDOT with controlled degree of polymerization, soluble in common organic and chlorinated solvents and with improved conductivity, 210 S/cm, was performed. This method includes: direct oxidative polycondensation of 3,4-Ethylenedioxythiophene (EDOT) in the presence of a cross-linkable end-capper, i.e. Methacrylate end-capped EDOT prepared via Friedel Crafts acylation with Methacryloyl chloride and oxidant species, i.e. ferric sulfate. Furthermore, the oxidative polycondensation of EDOT monomer and Methacrylate end-capped EDOT in the presence of Sulfonated Polyethersulfone (SPES)- characterized by different degree of Sulfonation (DS)- as dopant agent was performed, leading to functional end-capped conducting PEDOT, easy to process and pattern, with conductivity of 210 S/cm, 50 S/cm higher than the one of commercial PEDOT.

  3. Self-healing hyperbranched poly(aroyltriazole)s

    PubMed Central

    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.

  4. On imparting radiopacity to a poly(urethane urea).

    PubMed

    James, Nirmala R; Jayakrishnan, A

    2007-07-01

    A poly(urethane urea) (PUU) synthesized from 2,4-toluene diisocyanate (TDI) and polyethylene glycol (PEG) with ethylenediamine (ED) as the chain extender was rendered radiopaque by attaching 3,4,5-triiodobenzoic acid (TIB) onto the polymer backbone. The radiopaque polyurethane obtained was characterized by infra red (IR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-radiography. By optimizing the reaction conditions, it was possible to carry out the modification without adversely affecting the properties of the starting polymer significantly. IR spectral evidence suggested that the hydrogen bonded structure of PUU remained undisrupted even after modification. However, the product exhibited altered thermal characteristics when compared to the parent polymer. Degradation characteristics as observed from the TGA remained unchanged, while one of the glass transitions got shifted to a lower temperature. The observed changes in thermal characteristics were explained on the basis of possible inter-phase mixing and the changes in the close packing of the polymer chains by the introduction of bulky iodine atoms. PMID:17445880

  5. Synthesis, Characterization, and Electroluminescence Properties of Poly(fluorenevinylene benzobisthiazoles)

    SciTech Connect

    Intemann, Jeremy J.; Mike, Jared F.; Cai, Min; Barnes, Charles A.; Xiao, Teng; Roggers, Robert A.; Shinar, Joseph; Shinar, Ruth; Jeffries-EL, Malika

    2012-11-26

    A series of vinylene-linked copolymers based on electron-deficient benzobisthiazole and electron-rich fluorene moieties were synthesized via Horner–Wadsworth–Emmons polymerization. Three different polymers P1, P2, and P3, were prepared bearing octyl, 3,7-dimethyloctyl, and 2-(2-ethoxy)ethoxyethyl side chains, respectively. The polymers all possessed moderate molecular weights, good solubility in aprotic organic solvents, and high fluorescence quantum efficiencies in dilute solutions. P2, which bore branched 3,7-dimethyloctyl side chains, exhibited better solubility than the other polymers, but also exhibited the lowest thermal decomposition temperature of all polymers. Overall, the impact of the side chains on the polymers optical properties in solution was negligible as all three polymers gave similar absorption and emission spectra in both solution and film. Guest-host light-emitting diodes using dilute blends of the polymers in a poly(N-vinylcarbazole) host gave blue-green emission with P2 exhibiting the highest luminous efficiency, 0.61 Cd/A at ~500 nm. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

  6. Poly(arylene ether)s containing pendent ethynyl groups

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M. (Inventor); Jensen, Brian J. (Inventor)

    1996-01-01

    Poly(arylene ether)s containing pendent ethynyl and substituted ethynyl groups and poly(arylene ether) copolymers containing pendent ethynyl and substituted ethynyl groups are readily prepared from bisphenols containing ethynyl and substituted ethynyl groups. The resulting polymers are cured up to 350.degree. C. to provide crosslinked poly(arylene ether)s with good solvent resistance, high strength and modulus.

  7. Role of β-hydroxybutyrate, its polymer poly-β-hydroxybutyrate and inorganic polyphosphate in mammalian health and disease

    PubMed Central

    Dedkova, Elena N.; Blatter, Lothar A.

    2014-01-01

    We provide a comprehensive review of the role of β-hydroxybutyrate (β-OHB), its linear polymer poly-β-hydroxybutyrate (PHB), and inorganic polyphosphate (polyP) in mammalian health and disease. β-OHB is a metabolic intermediate that constitutes 70% of ketone bodies produced during ketosis. Although ketosis has been generally considered as an unfavorable pathological state (e.g., diabetic ketoacidosis in type-1 diabetes mellitus), it has been suggested that induction of mild hyperketonemia may have certain therapeutic benefits. β-OHB is synthesized in the liver from acetyl-CoA by β-OHB dehydrogenase and can be used as alternative energy source. Elevated levels of PHB are associated with pathological states. In humans, short-chain, complexed PHB (cPHB) is found in a wide variety of tissues and in atherosclerotic plaques. Plasma cPHB concentrations correlate strongly with atherogenic lipid profiles, and PHB tissue levels are elevated in type-1 diabetic animals. However, little is known about mechanisms of PHB action especially in the heart. In contrast to β-OHB, PHB is a water-insoluble, amphiphilic polymer that has high intrinsic viscosity and salt-solvating properties. cPHB can form non-specific ion channels in planar lipid bilayers and liposomes. PHB can form complexes with polyP and Ca2+ which increases membrane permeability. The biological roles played by polyP, a ubiquitous phosphate polymer with ATP-like bonds, have been most extensively studied in prokaryotes, however polyP has recently been linked to a variety of functions in mammalian cells, including blood coagulation, regulation of enzyme activity in cancer cells, cell proliferation, apoptosis and mitochondrial ion transport and energy metabolism. Recent evidence suggests that polyP is a potent activator of the mitochondrial permeability transition pore in cardiomyocytes and may represent a hitherto unrecognized key structural and functional component of the mitochondrial membrane system. PMID

  8. [gamma]-Irradiation-induced grafting of poly(styrenesulfonate) to poly(tetrafluoroethylene) shielded microelectrodes

    SciTech Connect

    Ramos, B.L.; Blubaugh, E.A.; Ridgway, T.H.; Heineman, W.R. )

    1994-06-01

    A new method for the fabrication and polymer modification of microelectrodes is described. These electrodes are constructed by heat sealing the electroactive material in dual shrink/melt poly(tetrafluoroethylene) (PTFE) under vacuum. The PTFE shield may be activated to provide a support upon which polymers of interest may be grafted. [gamma]-Irradiation was used to graft polymerize styrene to the surface. The poly-(styrene) was subsequently sulfonated with chlorosulfonic acid to form poly(styrenesulfonate). Scanning electron microscopy and Raman microspectroscopy provide evidence that the poly-(styrenesulfonate) film has been formed and extends over the electrode material. Voltammetry indicates that hexaammine-ruthenium(III) cation is preconcentrated and stabilized via an association with the polymer film. 24 refs., 8 figs., 2 tabs.

  9. A Z-like form of poly(dA-dC).poly(dG-dT) in solution?

    PubMed Central

    Vorlíckovă, M; Kypr, J; Stokrová, S; Sponar, J

    1982-01-01

    Circular dichroism was used to study changes in conformation of poly(dA-dC).poly(dG-dT) caused by a high concentration of various monovalent salts. It was found that CsF induced the gradual appearance of a negative band in the long wavelength part of the CD spectrum of poly(dA-dC).poly(dG-dT), which might reflect a transition of this DNA toward a Z-like structure. PMID:7063415

  10. Mg2+ ion effect on conformational equilibrium of poly A . 2 poly U and poly A poly U in aqueous solutions.

    PubMed

    Sorokin, Victor A; Valeev, Vladimir A; Gladchenko, Galina O; Degtiar, Marina V; Karachevtsev, Victor A; Blagoi, Yuri P

    2003-01-15

    Differential UV spectroscopy and thermal denaturation were used to study the Mg(2+) ion effect on the conformational equilibrium in poly A.2 poly U (A2U) and poly A . poly U (AU) solutions at low (0.01 M Na(+)) and high (0.1 M Na(+)) ionic strengths. Four complete phase diagrams were obtained for Mg(2+)-polynucleotide complexes in ranges of temperatures 20-96 degrees C and concentrations (10(-5)-10(-2)) M Mg(2+). Three of them have a 'critical' point at which the type of the conformational transition changes. The value of the 'critical' concentration ([Mg(t)(2+)](cr)=(4.5+/-1.0) x 10(-5) M) is nearly independent of the initial conformation of polynucleotides (AU, A2U) and of Na(+) contents in the solution. Such a value is observed for Ni(2+) ions too. The phase diagram of the (A2U+Mg(2+)) complex with 0.01 M Na(+) has no 'critical' point: temperatures of (3-->2) and (2-->1) transitions increase in the whole Mg(2+) range. In (AU+Mg(2+)) phase diagram at 0.01 M Na(+) the temperature interval in which triple helices are formed and destroyed is several times larger than at 0.1 M Na(+). Using the ligand theory, a qualitative thermodynamic analysis of the phase diagrams was performed. PMID:12568931

  11. The Cal Poly aircraft design program

    NASA Technical Reports Server (NTRS)

    Sandlin, Doral R.; Van't Riet, Robert

    1993-01-01

    Discussed is the aircraft design program at Cal Poly, SLO. The history of the program and the impact of the NASA/USRA ADP are presented. Examples of student design accomplishments are included. Questions on how the aircraft design education process can be improved are postulated.

  12. Poly(aniline) in corrosion resistant coatings

    SciTech Connect

    McAndrew, T.P.; Miller, S.A.; Gilicinski, A.G.; Robeson, L.M.

    1996-10-01

    During the past two decades, one of the most active fields of solid-state science has been electrically conductive polymers. These are polymers which are insulators as prepared, but which can be converted to polymers having many or all the properties of a metal, by virtue of appropriate chemical/electrochemical oxidation or reduction. Typically, applications examined for electrically conductive polymers have been in areas such as rechargeable batteries and charge dissipative coatings. Recently it has been reported that poly(aniline), in its electrically conductive, protonated form, shows excellent performance as a coating for preventing the corrosion of carbon steel. The present research has shown that in fact, the non-conductive, unprotonated form of poly(aniline) shows even better performance in corrosion prevention than the conductive form. Moreover, it has been shown that poly(aniline) can be blended with other polymers to improve their corrosion resistance performance (e.g., polyimides), or used as a hardener for epoxides or diisocyanates, to give very good corrosion resistant coatings. Poly(aniline) performance is explained in terms of its ability to form dense, adherent films, and create a basic surface on carbon steel surfaces.

  13. TOPICAL REVIEW Engineering of poly(ethylene glycol) chain-tethered surfaces to obtain high-performance bionanoparticles

    NASA Astrophysics Data System (ADS)

    Nagasaki, Yukio

    2010-10-01

    A poly(ethylene glycol)-b-poly[2-(N,N-dimethylamino)ethyl methacrylate] block copolymer possessing a reactive acetal group at the end of the poly(ethylene glycol) (PEG) chain, that is, acetal-PEG-b-PAMA, was synthesized by a proprietary polymerization technique. Gold nanoparticles (GNPs) were prepared using the thus-synthesized acetal-PEG-b-PAMA block copolymer. The PEG-b-PAMA not only acted as a reducing agent of aurate ions but also attached to the nanoparticle surface. The GNPs obtained had controlled sizes and narrow size distributions. They also showed high dispersion stability owing to the presence of PEG tethering chains on the surface. The same strategy should also be applicable to the fabrication of semiconductor quantum dots and inorganic porous nanoparticles. The preparation of nanoparticles in situ, i.e. in the presence of acetal-PEG-b-PAMA, gave the most densely packed polymer layer on the nanoparticle surface; this was not observed when coating preformed nanoparticles. PEG/polyamine block copolymer was more functional on the metal surface than PEG/polyamine graft copolymer, as confirmed by angle-dependent x-ray photoelectron spectroscopy. We successfully solubilized the C60 fullerene into aqueous media using acetal-PEG-b-PAMA. A C60/acetal-PEG-b-PAMA complex with a size below 5 nm was obtained by dialysis. The preparation and characterization of these materials are described in this review.

  14. Polymer-additive extraction via pressurized fluids and organic solvents of variously cross-linked poly(methylmethacrylates).

    PubMed

    Nazem, N; Taylor, L T

    2002-04-01

    Variously cross-linked poly(methylmethacrylates) (PMMAs) are synthesized with three additives incorporated at theoretically 1000 microg of the additive per gram of prepared polymer. The additives are Irganox 1010, Irganox 1076, and Irgafos 168. The in-house" synthesized polyacrylates are then subjected to supercritical fluid extraction (SFE) to determine if additive recovery is a function of percent cross-linking. Although considerable work in this regard has been performed with non-cross-linked polyolefins, the literature is lacking regarding polyacrylates. Some additive degradation apparently occurs during the synthesis, as judged by the increased complexity of the extract high-performance liquid chromatographic trace and the low percent recoveries observed especially for the Irganoxes. For low polymer cross-linking (1%), it appears that both PMMA synthetic reproducibility and readily observed polymer swelling during SFE are serious issues that adversely affect additive percent recovery and precision of results. Higher percent cross-linking yields more consistent analytical data than low percent cross-linking, even though the amount of additive extracted in all PMMA samples (regardless of cross-linking percentage) is essentially the same whether the extraction is via SFE or liquid-solid extraction with methylene chloride. Results for comparably cross-linked poly(ethylmethacrylate) and poly(butylmethacrylate) are similar to PMMA. PMID:12004935

  15. Biosynthesis of poly(glycolate-co-lactate-co-3-hydroxybutyrate) from glucose by metabolically engineered Escherichia coli.

    PubMed

    Li, Zheng-Jun; Qiao, Kangjian; Shi, Weichao; Pereira, Brian; Zhang, Haoran; Olsen, Bradley D; Stephanopoulos, Gregory

    2016-05-01

    Metabolically engineered Escherichia coli strains were constructed to effectively produce novel glycolate-containing biopolymers from glucose. First, the glyoxylate bypass pathway and glyoxylate reductase were engineered such as to generate glycolate. Second, glycolate and lactate were activated by the Megasphaera elsdenii propionyl-CoA transferase to synthesize glycolyl-CoA and lactyl-CoA, respectively. Third, β-ketothiolase and acetoacetyl-CoA reductase from Ralstonia eutropha were introduced to synthesize 3-hydroxybutyryl-CoA from acetyl-CoA. At last, the Ser325Thr/Gln481Lys mutant of polyhydroxyalkanoate (PHA) synthase from Pseudomonas sp. 61-3 was over-expressed to polymerize glycolyl-CoA, lactyl-CoA and 3-hydroxybutyryl-CoA to produce poly(glycolate-co-lactate-co-3-hydroxybutyrate). The recombinant E. coli was able to accumulate the novel terpolymer with a titer of 3.90g/l in shake flask cultures. The structure of the resulting polymer was chemically characterized by proton NMR analysis. Assessment of thermal and mechanical properties demonstrated that the produced terpolymer possessed decreased crystallinity and improved toughness, in comparison to poly(3-hydroxybutyrate) homopolymer. This is the first study reporting efficient microbial production of poly(glycolate-co-lactate-co-3-hydroxybutyrate) from glucose. PMID:26778413

  16. The Electronic Music Synthesizer and the Physics of Music

    ERIC Educational Resources Information Center

    Hartmann, W. M.

    1975-01-01

    Describes the principal modules of analog electronic music synthesizers and discusses some ways that a synthesizer has been used in demonstrations, in psychophysical experiments, and in an undergraduate laboratory course in the physics of music and acoustics. Considers the synthesis of both steady and transitory auditory phenomena. (Author/MLH)

  17. 21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) (CAS Reg. No. 24936-41-2) polymer produced by the polymerization of p-methylstyrene. (2) Rubber... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Poly(p-methylstyrene) and rubber-modified poly(p... Components of Single and Repeated Use Food Contact Surfaces § 177.1635 Poly(p-methylstyrene) and...

  18. MECHANICAL PROPERTIES OF BLENDS OF PAMAM DENDRIMERS WITH POLY(VINYL CHLORIDE) AND POLY(VINYL ACETATE)

    EPA Science Inventory

    Hybrid blends of poly(amidoamine) PAMAM dendrimers with two linear high polymers, poly(vinyl chloride), PVC, and poly(vinyl acetate), PVAc, are reported. The interaction between the blend components was studied using dynamic mechanical analysis, xenon nuclear magnetic resonacne ...

  19. Phosphoproteomic Approach to Characterize Protein Mono- and Poly(ADP-ribosyl)ation Sites from Cells

    PubMed Central

    2015-01-01

    Poly(ADP-ribose), or PAR, is a cellular polymer implicated in DNA/RNA metabolism, cell death, and cellular stress response via its role as a post-translational modification, signaling molecule, and scaffolding element. PAR is synthesized by a family of proteins known as poly(ADP-ribose) polymerases, or PARPs, which attach PAR polymers to various amino acids of substrate proteins. The nature of these polymers (large, charged, heterogeneous, base-labile) has made these attachment sites difficult to study by mass spectrometry. Here we propose a new pipeline that allows for the identification of mono(ADP-ribosyl)ation and poly(ADP-ribosyl)ation sites via the enzymatic product of phosphodiesterase-treated ADP-ribose, or phospho(ribose). The power of this method lies in the enrichment potential of phospho(ribose), which we show to be enriched by phosphoproteomic techniques when a neutral buffer, which allows for retention of the base-labile attachment site, is used for elution. Through the identification of PARP-1 in vitro automodification sites as well as endogenous ADP-ribosylation sites from whole cells, we have shown that ADP-ribose can exist on adjacent amino acid residues as well as both lysine and arginine in addition to known acidic modification sites. The universality of this technique has allowed us to show that enrichment of ADP-ribosylated proteins by macrodomain leads to a bias against ADP-ribose modifications conjugated to glutamic acids, suggesting that the macrodomain is either removing or selecting against these distinct protein attachments. Ultimately, the enrichment pipeline presented here offers a universal approach for characterizing the mono- and poly(ADP-ribosyl)ated proteome. PMID:24920161

  20. Quantitative proteomics profiling of the poly(ADP-ribose)-related response to genotoxic stress

    PubMed Central

    Gagné, Jean-Philippe; Pic, Émilie; Isabelle, Maxim; Krietsch, Jana; Éthier, Chantal; Paquet, Éric; Kelly, Isabelle; Boutin, Michel; Moon, Kyung-Mee; Foster, Leonard J.; Poirier, Guy G.

    2012-01-01

    Upon DNA damage induction, DNA-dependent poly(ADP-ribose) polymerases (PARPs) synthesize an anionic poly(ADP-ribose) (pADPr) scaffold to which several proteins bind with the subsequent formation of pADPr-associated multiprotein complexes. We have used a combination of affinity-purification methods and proteomics approaches to isolate these complexes and assess protein dynamics with respect to pADPr metabolism. As a first approach, we developed a substrate trapping strategy by which we demonstrate that a catalytically inactive Poly(ADP-ribose) glycohydrolase (PARG) mutant can act as a physiologically selective bait for the isolation of specific pADPr-binding proteins through its macrodomain-like domain. In addition to antibody-mediated affinity-purification methods, we used a pADPr macrodomain affinity resin to recover pADPr-binding proteins and their complexes. Second, we designed a time course experiment to explore the changes in the composition of pADPr-containing multiprotein complexes in response to alkylating DNA damage-mediated PARP activation. Spectral count clustering based on GeLC-MS/MS analysis was complemented with further analyses using high precision quantitative proteomics through isobaric tag for relative and absolute quantitation (iTRAQ)- and Stable isotope labeling by amino acids in cell culture (SILAC)-based proteomics. Here, we present a valuable resource in the interpretation of systems biology of the DNA damage response network in the context of poly(ADP-ribosyl)ation and provide a basis for subsequent investigations of pADPr-binding protein candidates. PMID:22669911