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Sample records for amphipathic dna polymers

  1. Amphipathic DNA polymers exhibit antiviral activity against systemic Murine Cytomegalovirus infection

    Directory of Open Access Journals (Sweden)

    Juteau Jean-Marc

    2009-12-01

    Full Text Available Abstract Background Phosphorothioated oligonucleotides (PS-ONs have a sequence-independent, broad spectrum antiviral activity as amphipathic polymers (APs and exhibit potent in vitro antiviral activity against a broad spectrum of herpesviruses: HSV-1, HSV-2, HCMV, VZV, EBV, and HHV-6A/B, and in vivo activity in a murine microbiocide model of genital HSV-2 infection. The activity of these agents against animal cytomegalovirus (CMV infections in vitro and in vivo was therefore investigated. Results In vitro, a 40 mer degenerate AP (REP 9 inhibited both murine CMV (MCMV and guinea pig CMV (GPCMV with an IC50 of 0.045 μM and 0.16 μM, respectively, and a 40 mer poly C AP (REP 9C inhibited MCMV with an IC50 of 0.05 μM. Addition of REP 9 to plaque assays during the first two hours of infection inhibited 78% of plaque formation whereas addition of REP 9 after 10 hours of infection did not significantly reduce the number of plaques, indicating that REP 9 antiviral activity against MCMV occurs at early times after infection. In a murine model of CMV infection, systemic treatment for 5 days significantly reduced virus replication in the spleens and livers of infected mice compared to saline-treated control mice. REP 9 and REP 9C were administered intraperitoneally for 5 consecutive days at 10 mg/kg, starting 2 days prior to MCMV infection. Splenomegaly was observed in infected mice treated with REP 9 but not in control mice or in REP 9 treated, uninfected mice, consistent with mild CpG-like activity. When REP 9C (which lacks CpG motifs was compared to REP 9, it exhibited comparable antiviral activity as REP 9 but was not associated with splenomegaly. This suggests that the direct antiviral activity of APs is the predominant therapeutic mechanism in vivo. Moreover, REP 9C, which is acid stable, was effective when administered orally in combination with known permeation enhancers. Conclusion These studies indicate that APs exhibit potent, well tolerated

  2. Effect of a novel amphipathic ionic liquid on lithium deposition in gel polymer electrolytes

    International Nuclear Information System (INIS)

    Choi, Nam-Soon; Koo, Bonjae; Yeon, Jin-Tak; Lee, Kyu Tae; Kim, Dong-Won

    2011-01-01

    Highlights: · Synthesis of a dimeric ionic liquid. · Gel polymer electrolytes providing uniform lithium deposit pathway. · An amphipathic ionic liquid locates at the interface between an electrolyte-rich phase and a polymer matrix in a gel polymer electrolyte. · The presence of PDMITFSI ionic liquid leads to the suppression of dendritic lithium formation on a lithium metal electrode. - Abstract: A novel dimeric ionic liquid based on imidazolium cation and bis(trifluoromethanesulfonyl) imide (TFSI) anion has been synthesized through a metathesis reaction. Its chemical shift values and thermal properties are identified via 1 H nuclear magnetic resonance (NMR) imaging and differential scanning calorimetry (DSC). The effect of the synthesized dimeric ionic liquid on the interfacial resistance of gel polymer electrolytes is described. Differences in the SEM images of lithium electrodes after lithium deposition with and without the 1,1'-pentyl-bis(2,3-dimethylimidazolium) bis(trifluoromethane-sulfonyl)imide (PDMITFSI) ionic liquid in gel polymer electrolytes are clearly discernible. This occurs because the PDMITFSI ionic liquid with hydrophobic moieties and polar groups modulates lithium deposit pathways onto the lithium metal anode. Moreover, high anodic stability for a gel polymer electrolyte with the PDMITFSI ionic liquid was clearly observed.

  3. Plasminogen activator inhibitor-1 polymers, induced by inactivating amphipathic organochemical ligands

    DEFF Research Database (Denmark)

    Pedersen, Katrine E; Einholm, Anja P; Christensen, Anni

    2003-01-01

    Negatively charged organochemical inactivators of the anti-proteolytic activity of plasminogen activator inhibitor-1 (PAI-1) convert it to inactive polymers. As investigated by native gel electrophoresis, the size of the PAI-1 polymers ranged from dimers to multimers of more than 20 units. As com...

  4. DNA: Polymer and molecular code

    Science.gov (United States)

    Shivashankar, G. V.

    1999-10-01

    The thesis work focusses upon two aspects of DNA, the polymer and the molecular code. Our approach was to bring single molecule micromanipulation methods to the study of DNA. It included a home built optical microscope combined with an atomic force microscope and an optical tweezer. This combined approach led to a novel method to graft a single DNA molecule onto a force cantilever using the optical tweezer and local heating. With this method, a force versus extension assay of double stranded DNA was realized. The resolution was about 10 picoN. To improve on this force measurement resolution, a simple light backscattering technique was developed and used to probe the DNA polymer flexibility and its fluctuations. It combined the optical tweezer to trap a DNA tethered bead and the laser backscattering to detect the beads Brownian fluctuations. With this technique the resolution was about 0.1 picoN with a millisecond access time, and the whole entropic part of the DNA force-extension was measured. With this experimental strategy, we measured the polymerization of the protein RecA on an isolated double stranded DNA. We observed the progressive decoration of RecA on the l DNA molecule, which results in the extension of l , due to unwinding of the double helix. The dynamics of polymerization, the resulting change in the DNA entropic elasticity and the role of ATP hydrolysis were the main parts of the study. A simple model for RecA assembly on DNA was proposed. This work presents a first step in the study of genetic recombination. Recently we have started a study of equilibrium binding which utilizes fluorescence polarization methods to probe the polymerization of RecA on single stranded DNA. In addition to the study of material properties of DNA and DNA-RecA, we have developed experiments for which the code of the DNA is central. We studied one aspect of DNA as a molecular code, using different techniques. In particular the programmatic use of template specificity makes

  5. Programmed Switching of Single Polymer Conformation on DNA Origami

    DEFF Research Database (Denmark)

    Krissanaprasit, Abhichart; Madsen, Mikael; Knudsen, Jakob Bach

    2016-01-01

    -molecule conjugated polymer. The polymer is functionalized with short single-stranded (ss) DNA strands that extend from the backbone of the polymer and serve as handles. The DNA polymer conjugate can be aligned on DNA origami in three well-defined geometries (straight line, left-turned, and right-turned pattern......) by DNA hybridization directed by single-stranded guiding strands and ssDNA tracks extending from the origami surface and polymer handle. We demonstrate switching of a conjugated organic polymer conformation between left- and right-turned conformations of the polymer on DNA origami based on toehold...

  6. Polymer multilayer tattooing for enhanced DNA vaccination

    Science.gov (United States)

    Demuth, Peter C.; Min, Younjin; Huang, Bonnie; Kramer, Joshua A.; Miller, Andrew D.; Barouch, Dan H.; Hammond, Paula T.; Irvine, Darrell J.

    2013-04-01

    DNA vaccines have many potential benefits but have failed to generate robust immune responses in humans. Recently, methods such as in vivo electroporation have demonstrated improved performance, but an optimal strategy for safe, reproducible, and pain-free DNA vaccination remains elusive. Here we report an approach for rapid implantation of vaccine-loaded polymer films carrying DNA, immune-stimulatory RNA, and biodegradable polycations into the immune-cell-rich epidermis, using microneedles coated with releasable polyelectrolyte multilayers. Films transferred into the skin following brief microneedle application promoted local transfection and controlled the persistence of DNA and adjuvants in the skin from days to weeks, with kinetics determined by the film composition. These ‘multilayer tattoo’ DNA vaccines induced immune responses against a model HIV antigen comparable to electroporation in mice, enhanced memory T-cell generation, and elicited 140-fold higher gene expression in non-human primate skin than intradermal DNA injection, indicating the potential of this strategy for enhancing DNA vaccination.

  7. Polymer multilayer tattooing for enhanced DNA vaccination

    Science.gov (United States)

    DeMuth, Peter C.; Min, Younjin; Huang, Bonnie; Kramer, Joshua A.; Miller, Andrew D.; Barouch, Dan H.; Hammond, Paula T.; Irvine, Darrell J.

    2014-01-01

    DNA vaccines have many potential benefits but have failed to generate robust immune responses in humans. Recently, methods such as in vivo electroporation have demonstrated improved performance, but an optimal strategy for safe, reproducible, and pain-free DNA vaccination remains elusive. Here we report an approach for rapid implantation of vaccine-loaded polymer films carrying DNA, immune-stimulatory RNA, and biodegradable polycations into the immune-cell-rich epidermis, using microneedles coated with releasable polyelectrolyte multilayers. Films transferred into the skin following brief microneedle application promoted local transfection and controlled the persistence of DNA and adjuvants in the skin from days to weeks, with kinetics determined by the film composition. These “multilayer tattoo” DNA vaccines induced immune responses against a model HIV antigen comparable to electroporation in mice, enhanced memory T-cell generation, and elicited 140-fold higher gene expression in non-human primate skin than intradermal DNA injection, indicating the potential of this strategy for enhancing DNA vaccination. PMID:23353628

  8. DNA-imprinted polymer nanoparticles with monodispersity and prescribed DNA-strand patterns

    Science.gov (United States)

    Trinh, Tuan; Liao, Chenyi; Toader, Violeta; Barłóg, Maciej; Bazzi, Hassan S.; Li, Jianing; Sleiman, Hanadi F.

    2018-02-01

    As colloidal self-assembly increasingly approaches the complexity of natural systems, an ongoing challenge is to generate non-centrosymmetric structures. For example, patchy, Janus or living crystallization particles have significantly advanced the area of polymer assembly. It has remained difficult, however, to devise polymer particles that associate in a directional manner, with controlled valency and recognition motifs. Here, we present a method to transfer DNA patterns from a DNA cage to a polymeric nanoparticle encapsulated inside the cage in three dimensions. The resulting DNA-imprinted particles (DIPs), which are 'moulded' on the inside of the DNA cage, consist of a monodisperse crosslinked polymer core with a predetermined pattern of different DNA strands covalently 'printed' on their exterior, and further assemble with programmability and directionality. The number, orientation and sequence of DNA strands grafted onto the polymeric core can be controlled during the process, and the strands are addressable independently of each other.

  9. Polymer- and salt-induced toroids of hexagonal DNA.

    OpenAIRE

    Ubbink, J; Odijk, T

    1995-01-01

    A model is proposed for polymer- and salt-induced toroidal condensates of DNA, based on a recent theory of the undulation enhancement of the electrostatic interaction in the bulk hexagonal phase of semiflexible polyions. In a continuum approximation, the thermodynamic potential of a monomolecular toroid may be split up in bulk, surface, and curvature contributions. With the help of an approximate analytical minimization procedure, the optimal torus dimensions are calculated as a function of t...

  10. The inhibition of anti-DNA binding to DNA by nucleic acid binding polymers.

    Directory of Open Access Journals (Sweden)

    Nancy A Stearns

    Full Text Available Antibodies to DNA (anti-DNA are the serological hallmark of systemic lupus erythematosus (SLE and can mediate disease pathogenesis by the formation of immune complexes. Since blocking immune complex formation can attenuate disease manifestations, the effects of nucleic acid binding polymers (NABPs on anti-DNA binding in vitro were investigated. The compounds tested included polyamidoamine dendrimer, 1,4-diaminobutane core, generation 3.0 (PAMAM-G3, hexadimethrine bromide, and a β-cylodextrin-containing polycation. As shown with plasma from patients with SLE, NABPs can inhibit anti-DNA antibody binding in ELISA assays. The inhibition was specific since the NABPs did not affect binding to tetanus toxoid or the Sm protein, another lupus autoantigen. Furthermore, the polymers could displace antibody from preformed complexes. Together, these results indicate that NABPs can inhibit the formation of immune complexes and may represent a new approach to treatment.

  11. Preparation, Single-Molecule Manipulation, and Energy Transfer Investigation of a Polyfluorene-graft-DNA polymer.

    Science.gov (United States)

    Madsen, Mikael; Christensen, Rasmus S; Krissanaprasit, Abhichart; Bakke, Mette R; Riber, Camilla F; Nielsen, Karina S; Zelikin, Alexander N; Gothelf, Kurt V

    2017-08-04

    Conjugated polymers have been intensively studied due to their unique optical and electronic properties combined with their physical flexibility and scalable bottom up synthesis. Although the bulk qualities of conjugated polymers have been extensively utilized in research and industry, the ability to handle and manipulate conjugated polymers at the nanoscale lacks significantly behind. Here, the toolbox for controlled manipulation of conjugated polymers was expanded through the synthesis of a polyfluorene-DNA graft-type polymer (poly(F-DNA)). The polymer possesses the characteristics associated with the conjugated polyfluorene backbone, but the protruding single-stranded DNA provides the material with an exceptional addressability. This study demonstrates controlled single-molecule patterning of poly(F-DNA), as well as energy transfer between two different polymer-DNA conjugates. Finally, highly efficient DNA-directed quenching of polyfluorene fluorescence was shown. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Electrochemical DNA Hybridization Sensors Based on Conducting Polymers

    Science.gov (United States)

    Rahman, Md. Mahbubur; Li, Xiao-Bo; Lopa, Nasrin Siraj; Ahn, Sang Jung; Lee, Jae-Joon

    2015-01-01

    Conducting polymers (CPs) are a group of polymeric materials that have attracted considerable attention because of their unique electronic, chemical, and biochemical properties. This is reflected in their use in a wide range of potential applications, including light-emitting diodes, anti-static coating, electrochromic materials, solar cells, chemical sensors, biosensors, and drug-release systems. Electrochemical DNA sensors based on CPs can be used in numerous areas related to human health. This review summarizes the recent progress made in the development and use of CP-based electrochemical DNA hybridization sensors. We discuss the distinct properties of CPs with respect to their use in the immobilization of probe DNA on electrode surfaces, and we describe the immobilization techniques used for developing DNA hybridization sensors together with the various transduction methods employed. In the concluding part of this review, we present some of the challenges faced in the use of CP-based DNA hybridization sensors, as well as a future perspective. PMID:25664436

  13. Electrochemical DNA Hybridization Sensors Based on Conducting Polymers

    Directory of Open Access Journals (Sweden)

    Md. Mahbubur Rahman

    2015-02-01

    Full Text Available Conducting polymers (CPs are a group of polymeric materials that have attracted considerable attention because of their unique electronic, chemical, and biochemical properties. This is reflected in their use in a wide range of potential applications, including light-emitting diodes, anti-static coating, electrochromic materials, solar cells, chemical sensors, biosensors, and drug-release systems. Electrochemical DNA sensors based on CPs can be used in numerous areas related to human health. This review summarizes the recent progress made in the development and use of CP-based electrochemical DNA hybridization sensors. We discuss the distinct properties of CPs with respect to their use in the immobilization of probe DNA on electrode surfaces, and we describe the immobilization techniques used for developing DNA hybridization sensors together with the various transduction methods employed. In the concluding part of this review, we present some of the challenges faced in the use of CP-based DNA hybridization sensors, as well as a future perspective.

  14. Adsorption of amphipathic dendrons on polystyrene nanoparticles.

    Science.gov (United States)

    Sakthivel, T; Florence, A T

    2003-03-18

    Adsorption of dendrons onto nanoparticles may provide new model structures which may be useful in drug and gene delivery. Tritiated amphipathic dendrons having three lipidic (C(14)) chains coupled to branched (dendritic) lysine head groups with 8, 16 or 32 free terminal amino groups have been synthesised by solid phase peptide techniques. The interaction between these tritiated dendrons and 200 nm polystyrene latex nanoparticles was investigated in phosphate buffered saline. The amount of dendron adsorbed increased with increasing concentration of dendrons and then decreased. Maximum adsorption of dendrons per gram of nanoparticles was found to be between 8.2 and 84 x 10(-6)M, the amounts adsorbed being inversely proportional to the number of amino groups present in the molecule. The number of dendron molecules adsorbed per nanoparticle was found to be between 430 and 4421. The degree of adsorption was found to be slightly altered by the temperature. Copyright 2002 Elsevier Science B.V.

  15. Like-charge attraction and opposite-charge decomplexation between polymers and DNA molecules

    OpenAIRE

    Buyukdagli, Sahin

    2016-01-01

    We scrutinize the effect of polyvalent ions on polymer-DNA interactions. We extend a recently developed test charge theory to the case of a stiff polymer interacting with a DNA molecule in an electrolyte mixture. The theory accounts for one-loop level electrostatic correlation effects such as the ionic cloud deformation around the strongly charged DNA molecule as well as image-charge forces induced by the low DNA permittivity. Our model can reproduce and explain various characteristics of the...

  16. Interaction of 18-residue peptides derived from amphipathic helical ...

    Indian Academy of Sciences (India)

    Madhsudhan

    interaction of proteins and peptides with membranes (Segrest ... favour surface activity have been described by Eisenberg et ... amphipathicity and propensity for α-helical conformation ..... Membrane destabilisation occurs due to electrostatic.

  17. DNA immobilization on polymer-modified Si surface by controlling pH

    International Nuclear Information System (INIS)

    Demirel, Goekcen Birlik; Caykara, Tuncer

    2009-01-01

    A novel approach based on polymer-modified Si surface as DNA sensor platforms is presented. The polymer-modified Si surface was prepared by using 3-(methacryloxypropyl)trimethoxysilane [γ-MPS] and poly(acrylamide) [PAAm]. Firstly, a layer of γ-MPS was formed on the hydroxylated silicon surface as a monolayer and then modified with different molecular weight of PAAm to form polymer-modified surface. The polymer-modified Si surface was used for dsDNA immobilization. All steps about formation of layer structure were characterized by ellipsometry, atomic force microscopy (AFM), attenuated total reflectance Fourier transformed infrared (ATR-FTIR), and contact angle (CA) measurements. We found that in this case the amount of dsDNA immobilized onto the surface was dictated by the electrostatic interaction between the substrate surface and the DNA. Our results thus demonstrated that DNA molecules could be immobilized differently onto the polymer-modified support surface via electrostatic interactions.

  18. IFITM3 requires an amphipathic helix for antiviral activity.

    Science.gov (United States)

    Chesarino, Nicholas M; Compton, Alex A; McMichael, Temet M; Kenney, Adam D; Zhang, Lizhi; Soewarna, Victoria; Davis, Matthew; Schwartz, Olivier; Yount, Jacob S

    2017-10-01

    Interferon-induced transmembrane protein 3 (IFITM3) is a cellular factor that blocks virus fusion with cell membranes. IFITM3 has been suggested to alter membrane curvature and fluidity, though its exact mechanism of action is unclear. Using a bioinformatic approach, we predict IFITM3 secondary structures and identify a highly conserved, short amphipathic helix within a hydrophobic region of IFITM3 previously thought to be a transmembrane domain. Consistent with the known ability of amphipathic helices to alter membrane properties, we show that this helix and its amphipathicity are required for the IFITM3-dependent inhibition of influenza virus, Zika virus, vesicular stomatitis virus, Ebola virus, and human immunodeficiency virus infections. The homologous amphipathic helix within IFITM1 is also required for the inhibition of infection, indicating that IFITM proteins possess a conserved mechanism of antiviral action. We further demonstrate that the amphipathic helix of IFITM3 is required to block influenza virus hemagglutinin-mediated membrane fusion. Overall, our results provide evidence that IFITM proteins utilize an amphipathic helix for inhibiting virus fusion. © 2017 The Authors.

  19. Cationic polymers for DNA origami coating - examining their binding efficiency and tuning the enzymatic reaction rates.

    Science.gov (United States)

    Kiviaho, Jenny K; Linko, Veikko; Ora, Ari; Tiainen, Tony; Järvihaavisto, Erika; Mikkilä, Joona; Tenhu, Heikki; Nonappa; Kostiainen, Mauri A

    2016-06-02

    DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The effect of the polymer structure on the binding was investigated and the toxicity of the polymer-origami complexes evaluated. The study shows that all of the analyzed polymers had a suitable binding efficiency irrespective of the block structure. It was also observed that the toxicity of polymer-origami complexes was insignificant at the biologically relevant concentration levels. Besides brick-like DNA origamis, tubular origami carriers equipped with enzymes were also coated with the polymers. By adjusting the amount of cationic polymers that cover the DNA structures, we showed that it is possible to control the enzyme kinetics of the complexes. This work gives a starting point for further development of biocompatible and effective polycation-based block copolymers that can be used in coating different DNA origami nanostructures for various bioapplications.

  20. Precision polymers and 3D DNA nanostructures: emergent assemblies from new parameter space.

    Science.gov (United States)

    Serpell, Christopher J; Edwardson, Thomas G W; Chidchob, Pongphak; Carneiro, Karina M M; Sleiman, Hanadi F

    2014-11-05

    Polymer self-assembly and DNA nanotechnology have both proved to be powerful nanoscale techniques. To date, most attempts to merge the fields have been limited to placing linear DNA segments within a polydisperse block copolymer. Here we show that, by using hydrophobic polymers of a precisely predetermined length conjugated to DNA strands, and addressable 3D DNA prisms, we are able to effect the formation of unprecedented monodisperse quantized superstructures. The structure and properties of larger micelles-of-prisms were probed in depth, revealing their ability to participate in controlled release of their constituent nanostructures, and template light-harvesting energy transfer cascades, mediated through both the addressability of DNA and the controlled aggregation of the polymers.

  1. Enhanced mitochondrial degradation of yeast cytochrome c with amphipathic structures.

    Science.gov (United States)

    Chen, Xi; Moerschell, Richard P; Pearce, David A; Ramanan, Durga D; Sherman, Fred

    2005-02-01

    The dispensable N-terminus of iso-1-cytochrome c (iso-1) in the yeast Saccharomyces cerevisiae was replaced by 11 different amphipathic structures. Rapid degradation of the corresponding iso-1 occurred, with the degree of degradation increasing with the amphipathic moments; and this amphipathic-dependent degradation was designated ADD. ADD occurred with the holo-forms in the mitochondria but not as the apo-forms in the cytosol. The extreme mutant type degraded with a half-life of approximately 12 min, whereas the normal iso-1 was stable over hours. ADD was influenced by the rho+/rho- state and by numerous chromosomal genes. Most importantly, ADD appeared to be specifically suppressed to various extents by deletions of any of the YME1, AFG3, or RCA1 genes encoding membrane-associated mitochondrial proteases, probably because the amphipathic structures caused a stronger association with the mitochondrial inner membrane and its associated proteases. The use of ADD assisted in the differentiation of substrates of different mitochondrial degradation pathways.

  2. Cationic polymers for DNA origami coating - examining their binding efficiency and tuning the enzymatic reaction rates

    Science.gov (United States)

    Kiviaho, Jenny K.; Linko, Veikko; Ora, Ari; Tiainen, Tony; Järvihaavisto, Erika; Mikkilä, Joona; Tenhu, Heikki; Nonappa, Affc; Kostiainen, Mauri A.

    2016-06-01

    DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The effect of the polymer structure on the binding was investigated and the toxicity of the polymer-origami complexes evaluated. The study shows that all of the analyzed polymers had a suitable binding efficiency irrespective of the block structure. It was also observed that the toxicity of polymer-origami complexes was insignificant at the biologically relevant concentration levels. Besides brick-like DNA origamis, tubular origami carriers equipped with enzymes were also coated with the polymers. By adjusting the amount of cationic polymers that cover the DNA structures, we showed that it is possible to control the enzyme kinetics of the complexes. This work gives a starting point for further development of biocompatible and effective polycation-based block copolymers that can be used in coating different DNA origami nanostructures for various bioapplications.DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The

  3. Synthesis and characterization of variable-architecture thermosensitive polymers for complexation with DNA.

    Science.gov (United States)

    Pennadam, Sivanand S; Ellis, James S; Lavigne, Matthieu D; Górecki, Dariusz C; Davies, Martyn C; Alexander, Cameron

    2007-01-02

    Copolymers of N-isopropylacrylamide with a fluorescent probe monomer were grafted to branched poly(ethyleneimine) to generate polycations that exhibited lower critical solution temperature (LCST) behavior. The structures of these polymers were confirmed by spectroscopy, and their phase transitions before and after complexation with DNA were followed using ultraviolet and fluorescence spectroscopy and light scattering. Interactions with DNA were investigated by ethidium bromide displacement assays, while temperature-induced changes in structure of both polymers and polymer-DNA complexes were evaluated by fluorescence spectroscopy, dynamic light scattering, laser Doppler anemometry, and atomic force microscopy (AFM) in water and buffer solutions. The results showed that changes in polymer architecture were mirrored by variations in the architectures of the complexes and that the overall effect of the temperature-mediated changes was dependent on the graft polymer architecture and content, as well as the solvent medium, concentrations, and stoichiometries of the complexes. Furthermore, AFM indicated subtle changes in polymer-DNA complexes at the microstructural level that could not be detected by light scattering techniques. Uniquely, variable-temperature aqueous-phase AFM was able to show that changes in the structures of these complexes were not uniform across a population of polymer-DNA condensates, with isolated complexes compacting above LCST even though the sample as a whole showed a tendency for aggregation of complexes above LCST over time. These results indicate that sample heterogeneities can be accentuated in responsive polymer--DNA complexes through LCST-mediated changes--a factor that is likely to be important in cellular uptake and nucleic acid transport.

  4. Elucidation of polymer induced DNA condensation. Visualisation at the single molecular level

    International Nuclear Information System (INIS)

    Martin, Alison Laura

    2002-01-01

    DNA condensation is a phenomenon that has stimulated interest from biologists, physicists, and polymer chemists for decades. At the cellular level, this process is key to the packing of DNA within the nuclear envelope, and the exposure of the appropriate nucleic acid sequences in order for transcription to occur, and proteins to be produced. The advent of gene therapy has led to an invigoration of this subject area. In order to successfully deliver to, and transfect target cells, many delivery vectors condense the therapeutic DNA into small compact particles. The nature of these particles have a considerable influence on the ultimate expression of the administered nucleic acid material. In addition, at its most fundamental, DNA itself is a classical polyelectrolyte polymer, the behaviour of which has applicability to other charged polymeric systems. There are two core interwound themes to this investigation; the visualisation of DNA condensate morphology at ultra-resolution, and the elucidation of the mechanisms of formation of these structures. The technique of atomic force microscopy is central to these investigations. Methodologies have been devised allowing the visualisation of the tertiary structure and conformational behaviour of individual DNA condensates in near in situ conditions. Condensation of the nucleic acid material has been induced by two classes of cation; small molecular cations, like those found within eukaryotic cells, and a range of cationic polymers. The cationic polymers investigated all have considerable potential as gene delivery vectors. The resultant DNA condensates have been assessed and contrasted in terms of their tertiary morphology, lateral dimensions, and structural volume. Assessments have also been made regarding the influence of the molecular architecture of the cationic moiety and the nature of the input nucleic acid material on the resultant DNA condensates. With regard to the elucidation of the mechanisms of DNA condensate

  5. Role of special cross-links in structure formation of bacterial DNA polymer

    Science.gov (United States)

    Agarwal, Tejal; Manjunath, G. P.; Habib, Farhat; Lakshmi Vaddavalli, Pavana; Chatterji, Apratim

    2018-01-01

    Using data from contact maps of the DNA-polymer of Escherichia coli (E. Coli) (at kilobase pair resolution) as an input to our model, we introduce cross-links between monomers in a bead-spring model of a ring polymer at very specific points along the chain. Via suitable Monte Carlo simulations, we show that the presence of these cross-links leads to a particular organization of the chain at large (micron) length scales of the DNA. We also investigate the structure of a ring polymer with an equal number of cross-links at random positions along the chain. We find that though the polymer does get organized at the large length scales, the nature of the organization is quite different from the organization observed with cross-links at specific biologically determined positions. We used the contact map of E. Coli bacteria which has around 4.6 million base pairs in a single circular chromosome. In our coarse-grained flexible ring polymer model, we used 4642 monomer beads and observed that around 80 cross-links are enough to induce the large-scale organization of the molecule accounting for statistical fluctuations caused by thermal energy. The length of a DNA chain even of a simple bacterial cell such as E. Coli is much longer than typical proteins, hence we avoided methods used to tackle protein folding problems. We define new suitable quantities to identify the large scale structure of a polymer chain with a few cross-links.

  6. DNA immobilization and detection on cellulose paper using a surface grown cationic polymer via ATRP.

    Science.gov (United States)

    Aied, Ahmed; Zheng, Yu; Pandit, Abhay; Wang, Wenxin

    2012-02-01

    Cationic polymers with various structures have been widely investigated in the areas of medical diagnostics and molecular biology because of their unique binding properties and capability to interact with biological molecules in complex biological environments. In this work, we report the grafting of a linear cationic polymer from an atom transfer radical polymerization (ATRP) initiator bound to cellulose paper surface. We show successful binding of ATRP initiator onto cellulose paper and grafting of polymer chains from the immobilized initiator with ATRP. The cellulose paper grafted polymer was used in combination with PicoGreen (PG) to demonstrate detection of nucleic acids in the nanogram range in homogeneous solution and in a biological sample (serum). The results showed specific identification of hybridized DNA after addition of PG in both solutions.

  7. A look at the effect of sequence complexity on pressure destabilisation of DNA polymers.

    Science.gov (United States)

    Rayan, Gamal; Macgregor, Robert B

    2015-04-01

    Our previous studies on the helix-coil transition of double-stranded DNA polymers have demonstrated that molar volume change (ΔV) accompanying the thermally-induced transition can be positive or negative depending on the experimental conditions, that the pressure-induced transition is more cooperative than the heat-induced transition [Rayan and Macgregor, J Phys Chem B2005, 109, 15558-15565], and that the pressure-induced transition does not occur in the absence of water [Rayan and Macgregor, Biophys Chem, 2009, 144, 62-66]. Additionally, we have shown that ΔV values obtained by pressure-dependent techniques differ from those obtained by ambient pressure techniques such as PPC [Rayan et al. J Phys Chem B2009, 113, 1738-1742] thus shedding light on the effects of pressure on DNA polymers. Herein, we examine the effect of sequence complexity, and hence cooperativity on pressure destabilisation of DNA polymers. Working with Clostridium perfringes DNA under conditions such that the estimated ΔV of the helix-coil transition corresponds to -1.78 mL/mol (base pair) at atmospheric pressure, we do not observe the pressure-induced helix-coil transition of this DNA polymer, whereas synthetic copolymers poly[d(A-T)] and poly[d(I-C)] undergo cooperative pressure-induced transitions at similar ΔV values. We hypothesise that the reason for the lack of pressure-induced helix-coil transition of C. perfringens DNA under these experimental conditions lies in its sequence complexity. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. DNA-inspired hierarchical polymer design: electrostatics and hydrogen bonding in concert.

    Science.gov (United States)

    Hemp, Sean T; Long, Timothy E

    2012-01-01

    Nucleic acids and proteins, two of nature's biopolymers, assemble into complex structures to achieve desired biological functions and inspire the design of synthetic macromolecules containing a wide variety of noncovalent interactions including electrostatics and hydrogen bonding. Researchers have incorporated DNA nucleobases into a wide variety of synthetic monomers/polymers achieving stimuli-responsive materials, supramolecular assemblies, and well-controlled macromolecules. Recently, scientists utilized both electrostatics and complementary hydrogen bonding to orthogonally functionalize a polymer backbone through supramolecular assembly. Diverse macromolecules with noncovalent interactions will create materials with properties necessary for biomedical applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Structuring polymers for delivery of DNA-based therapeutics: updated insights.

    Science.gov (United States)

    Gupta, Madhu; Tiwari, Shailja; Vyas, Suresh

    2012-01-01

    Gene therapy offers greater opportunities for treating numerous incurable diseases from genetic disorders, infections, and cancer. However, development of appropriate delivery systems could be one of the most important factors to overcome numerous biological barriers for delivery of various therapeutic molecules. A number of nonviral polymer-mediated vectors have been developed for DNA delivery and offer the potential to surmount the associated problems of their viral counterpart. To address the concerns associated with safety issues, a wide range of polymeric vectors are available and have been utilized successfully to deliver their therapeutics in vivo. Today's research is mainly focused on the various natural or synthetic polymer-based delivery carriers that protect the DNA molecule from degradation, which offer specific targeting to the desired cells after systemic administration, have transfection efficiencies equivalent to virus-mediated gene delivery, and have long-term gene expression through sustained-release mechanisms. This review explores an updated overview of different nonviral polymeric delivery system for delivery of DNA-based therapeutics. These polymeric carriers have been evaluated in vitro and in vivo and are being utilized in various stages of clinical evaluation. Continued research and understanding of the principles of polymer-based gene delivery systems will enable us to develop new and efficient delivery systems for the delivery of DNA-based therapeutics to achieve the goal of efficacious and specific gene therapy for a vast array of clinical disorders as the therapeutic solutions of tomorrow.

  10. POLYSACCHARIDES AND eDNA AID BACTERIAL ATTACHMENT TO POLYMER BRUSH COATINGS (PLL-g-PEG)

    DEFF Research Database (Denmark)

    Zeng, Guanghong; Ogaki, Ryosuke; Regina, Viduthalai R.

    measured the adsorption of peptides, polysaccharides and DNA to these coatings, as they represent bacterial adhesins with very different properties. While protein adsorption was minimized, we found considerable adsorption of polysaccharides, and exposure to DNA resulted in complete desorption...... of the conventional coating. These results explain why S. epidermidis, which produces polysaccharides and extracellular DNA, could successfully colonize the conventional PLL-g-PEG coatings. The ability of high-density PLL-g-PEG to resist polysaccharides, DNA, and bacterial adhesion of all strains is thus highly......Polymer brush coatings of poly(ethylene glycol) are considered the gold standard for nonfouling surfaces, but nevertheless, a few bacteria manage to attach and initiate biofilm formation on these coatings. To achieve robust resistance against bacterial adhesion and biofilm formation, grafting...

  11. Highly sensitive polymer-based cantilever-sensors for DNA detection

    International Nuclear Information System (INIS)

    Calleja, M.; Nordstroem, M.; Alvarez, M.; Tamayo, J.; Lechuga, L.M.; Boisen, A.

    2005-01-01

    We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel polymer material SU-8. The low Young's modulus of the polymer, 40 times lower than that of silicon, enables to improve the sensitivity of the sensor device for target detection. The mechanical properties of SU-8 cantilevers, such as spring constant, resonant frequency and quality factor are characterized as a function of the dimensions and the medium. The devices have been tested for measurement of the adsorption of single stranded DNA and subsequent interstitial adsorption of lateral spacer molecules. We demonstrate that sensitivity is enhanced by a factor of six compared to that of commercial silicon nitride cantilevers

  12. Highly sensitive polymer-based cantilever-sensors for DNA detection

    Energy Technology Data Exchange (ETDEWEB)

    Calleja, M. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain) and Mikroelektronics Centret, Technical University of Denmark, 345E, DK-2800, Lyngby (Denmark)]. E-mail: mcalleja@imm.cnm.csic.es; Nordstroem, M. [Mikroelektronics Centret, Technical University of Denmark, 345E, DK-2800, Lyngby (Denmark); Alvarez, M. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain); Tamayo, J. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain); Lechuga, L.M. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain); Boisen, A. [Mikroelektronics Centret, Technical University of Denmark, 345E, DK-2800, Lyngby (Denmark)

    2005-11-15

    We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel polymer material SU-8. The low Young's modulus of the polymer, 40 times lower than that of silicon, enables to improve the sensitivity of the sensor device for target detection. The mechanical properties of SU-8 cantilevers, such as spring constant, resonant frequency and quality factor are characterized as a function of the dimensions and the medium. The devices have been tested for measurement of the adsorption of single stranded DNA and subsequent interstitial adsorption of lateral spacer molecules. We demonstrate that sensitivity is enhanced by a factor of six compared to that of commercial silicon nitride cantilevers.

  13. Light-Induced Local Heating for Thermophoretic Manipulation of DNA in Polymer Micro- and Nanochannels

    DEFF Research Database (Denmark)

    Thamdrup, Lasse Højlund; Larsen, Niels Bent; Kristensen, Anders

    2010-01-01

    We present a method for making polymer chips with a narrow-band near-infrared absorber layer that enables light-induced local heating of liquids inside fluidic micro- and nanochannels fabricated by thermal imprint in polymethyl methacrylate. We have characterized the resulting liquid temperature...... profiles in microchannels using the temperature dependent fluorescence of the complex [Ru(bpy)3]2+. We demonstrate thermophoretic manipulation of individual YOYO-1 stained T4 DNA molecules inside micro- and nanochannels....

  14. Amphipathic α-Helices in Apolipoproteins Are Crucial to the Formation of Infectious Hepatitis C Virus Particles

    Science.gov (United States)

    Nakamura, Shota; Ono, Chikako; Shiokawa, Mai; Yamamoto, Satomi; Motomura, Takashi; Okamoto, Toru; Okuzaki, Daisuke; Yamamoto, Masahiro; Saito, Izumu; Wakita, Takaji; Koike, Kazuhiko; Matsuura, Yoshiharu

    2014-01-01

    Apolipoprotein B (ApoB) and ApoE have been shown to participate in the particle formation and the tissue tropism of hepatitis C virus (HCV), but their precise roles remain uncertain. Here we show that amphipathic α-helices in the apolipoproteins participate in the HCV particle formation by using zinc finger nucleases-mediated apolipoprotein B (ApoB) and/or ApoE gene knockout Huh7 cells. Although Huh7 cells deficient in either ApoB or ApoE gene exhibited slight reduction of particles formation, knockout of both ApoB and ApoE genes in Huh7 (DKO) cells severely impaired the formation of infectious HCV particles, suggesting that ApoB and ApoE have redundant roles in the formation of infectious HCV particles. cDNA microarray analyses revealed that ApoB and ApoE are dominantly expressed in Huh7 cells, in contrast to the high level expression of all of the exchangeable apolipoproteins, including ApoA1, ApoA2, ApoC1, ApoC2 and ApoC3 in human liver tissues. The exogenous expression of not only ApoE, but also other exchangeable apolipoproteins rescued the infectious particle formation of HCV in DKO cells. In addition, expression of these apolipoproteins facilitated the formation of infectious particles of genotype 1b and 3a chimeric viruses. Furthermore, expression of amphipathic α-helices in the exchangeable apolipoproteins facilitated the particle formation in DKO cells through an interaction with viral particles. These results suggest that amphipathic α-helices in the exchangeable apolipoproteins play crucial roles in the infectious particle formation of HCV and provide clues to the understanding of life cycle of HCV and the development of novel anti-HCV therapeutics targeting for viral assembly. PMID:25502789

  15. Comparative DNA isolation behaviours of silica and polymer based sorbents in batch fashion: monodisperse silica microspheres with bimodal pore size distribution as a new sorbent for DNA isolation.

    Science.gov (United States)

    Günal, Gülçin; Kip, Çiğdem; Eda Öğüt, S; İlhan, Hasan; Kibar, Güneş; Tuncel, Ali

    2018-02-01

    Monodisperse silica microspheres with bimodal pore-size distribution were proposed as a high performance sorbent for DNA isolation in batch fashion under equilibrium conditions. The proposed sorbent including both macroporous and mesoporous compartments was synthesized 5.1 μm in-size, by a "staged shape templated hydrolysis and condensation method". Hydrophilic polymer based sorbents were also obtained in the form of monodisperse-macroporous microspheres ca 5.5 μm in size, with different functionalities, by a developed "multi-stage microsuspension copolymerization" technique. The batch DNA isolation performance of proposed material was comparatively investigated using polymer based sorbents with similar morphologies. Among all sorbents tried, the best DNA isolation performance was achieved with the monodisperse silica microspheres with bimodal pore size distribution. The collocation of interconnected mesoporous and macroporous compartments within the monodisperse silica microspheres provided a high surface area and reduced the intraparticular mass transfer resistance and made easier both the adsorption and desorption of DNA. Among the polymer based sorbents, higher DNA isolation yields were achieved with the monodisperse-macroporous polymer microspheres carrying trimethoxysilyl and quaternary ammonium functionalities. However, batch DNA isolation performances of polymer based sorbents were significantly lower with respect to the silica microspheres.

  16. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, J.P.; Gilchrist, P.J. [Univ. of Edinburgh (United Kingdom); Duff, K.C. [Univ. of Edinburgh Medical School (United Kingdom); Saxena, A.M. [Brookhaven National Laboratory, Upton, NY (United States)

    1994-12-31

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein.

  17. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    International Nuclear Information System (INIS)

    Bradshaw, J.P.; Gilchrist, P.J.; Duff, K.C.; Saxena, A.M.

    1994-01-01

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein

  18. Smart DNA vectors based on cyclodextrin polymers: compaction and endosomal release.

    Science.gov (United States)

    Wintgens, Véronique; Leborgne, Christian; Baconnais, Sonia; Burckbuchler, Virginie; Le Cam, Eric; Scherman, Daniel; Kichler, Antoine; Amiel, Catherine

    2012-02-01

    Neutral β-cyclodextrin polymers (polyβCD) associated with cationic adamantyl derivatives (Ada) can be used to deliver plasmid DNA into cells. In absence of an endosomolytic agent, transfection efficiency remains low because most complexes are trapped in the endosomal compartment. We asked whether addition of an imidazole-modified Ada can increase efficiency of polyβCD/cationic Ada-based delivery system. We synthesized two adamantyl derivatives: Ada5, which has a spacer arm between the Ada moiety and a bi-cationic polar head group, and Ada6, which presents an imidazole group. Strength of association between polyβCD and Ada derivatives was evaluated by fluorimetric titration. Gel mobility shift assay, zeta potential, and dark field transmission electron microscopy experiments demonstrated the system allowed for efficient DNA compaction. In vitro transfection experiments performed on HepG2 and HEK293 cells revealed the quaternary system polyβCD/Ada5/Ada6/DNA has efficiency comparable to cationic lipid DOTAP. We successfully designed fine-tuned DNA vectors based on cyclodextrin polymers combined with two new adamantyl derivatives, leading to significant transfection associated with low toxicity.

  19. Protein-based polymers that bond to DNA : design of virus-like particles and supramolecular nanostructures

    NARCIS (Netherlands)

    Hernandez Garcia, A.

    2014-01-01

    In this thesis it is demonstrated that it is possible to use Protein-based Polymers (PbPs) as synthetic binders of DNA (or any other negatively charged polyelectrolyte). The PbPs co-assemble with their DNA templates to form highly organized virus-like particles and supramolecular structures. A

  20. A versatile palindromic amphipathic repeat coding sequence horizontally distributed among diverse bacterial and eucaryotic microbes

    Directory of Open Access Journals (Sweden)

    Glass John I

    2010-07-01

    Full Text Available Abstract Background Intragenic tandem repeats occur throughout all domains of life and impart functional and structural variability to diverse translation products. Repeat proteins confer distinctive surface phenotypes to many unicellular organisms, including those with minimal genomes such as the wall-less bacterial monoderms, Mollicutes. One such repeat pattern in this clade is distributed in a manner suggesting its exchange by horizontal gene transfer (HGT. Expanding genome sequence databases reveal the pattern in a widening range of bacteria, and recently among eucaryotic microbes. We examined the genomic flux and consequences of the motif by determining its distribution, predicted structural features and association with membrane-targeted proteins. Results Using a refined hidden Markov model, we document a 25-residue protein sequence motif tandemly arrayed in variable-number repeats in ORFs lacking assigned functions. It appears sporadically in unicellular microbes from disparate bacterial and eucaryotic clades, representing diverse lifestyles and ecological niches that include host parasitic, marine and extreme environments. Tracts of the repeats predict a malleable configuration of recurring domains, with conserved hydrophobic residues forming an amphipathic secondary structure in which hydrophilic residues endow extensive sequence variation. Many ORFs with these domains also have membrane-targeting sequences that predict assorted topologies; others may comprise reservoirs of sequence variants. We demonstrate expressed variants among surface lipoproteins that distinguish closely related animal pathogens belonging to a subgroup of the Mollicutes. DNA sequences encoding the tandem domains display dyad symmetry. Moreover, in some taxa the domains occur in ORFs selectively associated with mobile elements. These features, a punctate phylogenetic distribution, and different patterns of dispersal in genomes of related taxa, suggest that the

  1. A proline-hinge alters the characteristics of the amphipathic α-helical AMPs.

    Science.gov (United States)

    Lee, Jong Kook; Gopal, Ramamourthy; Park, Seong-Cheol; Ko, Hyun Sook; Kim, Yangmee; Hahm, Kyung-Soo; Park, Yoonkyung

    2013-01-01

    HP (2-20) is a 19-aa, amphipathic, α-helical peptide with antimicrobial properties that was derived from the N-terminus of Helicobacter pylori ribosomal protein L1. We previously showed that increasing the net hydrophobicity of HP (2-20) by substituting Trp for Gln(17) and Asp(19) (Anal 3) increased the peptide's antimicrobial activity. In hydrophobic medium, Anal 3 forms an amphipathic structure consisting of an N-terminal random coil region (residues 2-5) and an extended helical region (residues 6-20). To investigate the structure-activity relationship of Anal 3, we substituted Pro for Glu(9) (Anal 3-Pro) and then examined the new peptide's three-dimensional structure, antimicrobial activity and mechanism of action. Anal 3-Pro had an α-helical structure in the presence of trifluoroethanol (TFE) and sodium dodecyl sulfate (SDS). NMR spectroscopic analysis of Anal 3-Pro's tertiary structure in SDS micelles confirmed that the kink potential introduced by Pro(10) was responsible for the helix distortion. We also found that Anal 3-Pro exhibited about 4 times greater antimicrobial activity than Anal 3. Fluorescence activated flow cytometry and confocal fluorescence microscopy showed that incorporating a Pro-hinge into Anal 3 markedly reduced its membrane permeability so that it accumulated in the cytoplasm without remaining in the cell membrane. To investigate the translocation mechanism, we assessed its ability to release of FITC-dextran. The result showed Anal 3-Pro created a pore Candida albicans revealed that Anal 3-Pro and buforin II exert similar effects on cell membranes, whereas magainin 2 exerts a different, more damaging, effect. In addition, Anal 3-Pro assumed a helix-hinge-helix structure in the presence of biological membranes and formed micropores in both bacterial and fungal membranes, through which it entered the cytoplasm and tightly bound to DNA. These results indicate that the bending region of Anal 3- Pro peptide is prerequisite for effective

  2. A proline-hinge alters the characteristics of the amphipathic α-helical AMPs.

    Directory of Open Access Journals (Sweden)

    Jong Kook Lee

    Full Text Available HP (2-20 is a 19-aa, amphipathic, α-helical peptide with antimicrobial properties that was derived from the N-terminus of Helicobacter pylori ribosomal protein L1. We previously showed that increasing the net hydrophobicity of HP (2-20 by substituting Trp for Gln(17 and Asp(19 (Anal 3 increased the peptide's antimicrobial activity. In hydrophobic medium, Anal 3 forms an amphipathic structure consisting of an N-terminal random coil region (residues 2-5 and an extended helical region (residues 6-20. To investigate the structure-activity relationship of Anal 3, we substituted Pro for Glu(9 (Anal 3-Pro and then examined the new peptide's three-dimensional structure, antimicrobial activity and mechanism of action. Anal 3-Pro had an α-helical structure in the presence of trifluoroethanol (TFE and sodium dodecyl sulfate (SDS. NMR spectroscopic analysis of Anal 3-Pro's tertiary structure in SDS micelles confirmed that the kink potential introduced by Pro(10 was responsible for the helix distortion. We also found that Anal 3-Pro exhibited about 4 times greater antimicrobial activity than Anal 3. Fluorescence activated flow cytometry and confocal fluorescence microscopy showed that incorporating a Pro-hinge into Anal 3 markedly reduced its membrane permeability so that it accumulated in the cytoplasm without remaining in the cell membrane. To investigate the translocation mechanism, we assessed its ability to release of FITC-dextran. The result showed Anal 3-Pro created a pore <1.8 nm in diameter, which is similar to buforin II. Notably, scanning electron microscopic observation of Candida albicans revealed that Anal 3-Pro and buforin II exert similar effects on cell membranes, whereas magainin 2 exerts a different, more damaging, effect. In addition, Anal 3-Pro assumed a helix-hinge-helix structure in the presence of biological membranes and formed micropores in both bacterial and fungal membranes, through which it entered the cytoplasm and tightly

  3. Conducting polymer based DNA biosensor for the detection of the Bacillus cereus group species

    Science.gov (United States)

    Velusamy, Vijayalakshmi; Arshak, Khalil; Korostynska, Olga; Oliwa, Kamila; Adley, Catherine

    2009-05-01

    Biosensor designs are emerging at a significant rate and play an increasingly important role in foodborne pathogen detection. Conducting polymers are excellent tools for the fabrication of biosensors and polypyrrole has been used in the detection of biomolecules due to its unique properties. The prime intention of this paper was to pioneer the design and fabrication of a single-strand (ss) DNA biosensor for the detection of the Bacillus cereus (B.cereus) group species. Growth of B. cereus, results in production of several highly active toxins. Therefore, consumption of food containing >106 bacteria/gm may results in emetic and diarrhoeal syndromes. The most common source of this bacterium is found in liquid food products, milk powder, mixed food products and is of particular concern in the baby formula industry. The electrochemical deposition technique, such as cyclic voltammetry, was used to develop and test a model DNA-based biosensor on a gold electrode electropolymerized with polypyrrole. The electrically conducting polymer, polypyrrole is used as a platform for immobilizing DNA (1μg) on the gold electrode surface, since it can be more easily deposited from neutral pH aqueous solutions of pyrrolemonomers. The average current peak during the electrodeposition event is 288μA. There is a clear change in the current after hybridization of the complementary oligonucleotide (6.35μA) and for the noncomplementary oligonucleotide (5.77μA). The drop in current after each event was clearly noticeable and it proved to be effective.

  4. The Statistical Segment Length of DNA: Opportunities for Biomechanical Modeling in Polymer Physics and Next-Generation Genomics.

    Science.gov (United States)

    Dorfman, Kevin D

    2018-02-01

    The development of bright bisintercalating dyes for deoxyribonucleic acid (DNA) in the 1990s, most notably YOYO-1, revolutionized the field of polymer physics in the ensuing years. These dyes, in conjunction with modern molecular biology techniques, permit the facile observation of polymer dynamics via fluorescence microscopy and thus direct tests of different theories of polymer dynamics. At the same time, they have played a key role in advancing an emerging next-generation method known as genome mapping in nanochannels. The effect of intercalation on the bending energy of DNA as embodied by a change in its statistical segment length (or, alternatively, its persistence length) has been the subject of significant controversy. The precise value of the statistical segment length is critical for the proper interpretation of polymer physics experiments and controls the phenomena underlying the aforementioned genomics technology. In this perspective, we briefly review the model of DNA as a wormlike chain and a trio of methods (light scattering, optical or magnetic tweezers, and atomic force microscopy (AFM)) that have been used to determine the statistical segment length of DNA. We then outline the disagreement in the literature over the role of bisintercalation on the bending energy of DNA, and how a multiscale biomechanical approach could provide an important model for this scientifically and technologically relevant problem.

  5. Characterization of polymer, DNA-based, and silk thin film resistivities and of DNA-based films prepared for enhanced electrical conductivity

    Science.gov (United States)

    Yaney, Perry P.; Ouchen, Fahima; Grote, James G.

    2009-08-01

    DC resistivity studies were carried out on biopolymer films of DNA-CTMA and silk fibroin, and on selected traditional polymer films, including PMMA and APC. Films of DNA-CTMA versus molecular weight and with conductive dopants PCBM, BAYTRON P and ammonium tetrachloroplatinate are reported. The films were spin coated on glass slides configured for measurements of volume dc resistance. The measurements used the alternating polarity method to record the applied voltage-dependent current independent of charging and background currents. The Arrhenius equation plus a constant was fitted to the conductivity versus temperature data of the polymers and the non-doped DNA-based biopolymers with activation energies ranging from 0.8 to 1.4 eV.

  6. Biogenesis and the growth of DNA-like polymer chains: a computer simulation

    International Nuclear Information System (INIS)

    Herrmann, H.J.; Tsallis, C.

    1987-01-01

    We study, through computer simulation, a crucial step of Biogenesis, namely the growth of self-replicating codified DNA-like polymers starting from a mixture of oligomers. We have adopted the growth scheme that has been recently proposed by Ferreira and Tsallis which incorporates usual ideas of autocatalysis through complementary pairs and within which a central role is played by the hydrogen-like links (characterized by the probabilities p AT and p CG of chemical bonding of the A-T and C-G pairs respectively) between the two chains of the growing polymer. We find that the average equilibrium polymeric length ξ diverges, for any fixed ratio (1-p AT )/(1-p sub (CG)), as ξ ∝ 1/r1-p AT . Selection of patterns may happen at all stages and in particular at chemical equilibrium. Selection occurs via two different mechanisms: (i) away from the critical point p AT = p CG = 1 if p AT ≠ p CG ; (ii) both on and away from the critical point if the initial concentrations of nucleotides (A, T, C and G or their precursors) are different. (author) [pt

  7. Role of amphipathic helix of a herpesviral protein in membrane deformation and T cell receptor downregulation.

    Directory of Open Access Journals (Sweden)

    Chan-Ki Min

    2008-11-01

    Full Text Available Lipid rafts are membrane microdomains that function as platforms for signal transduction and membrane trafficking. Tyrosine kinase interacting protein (Tip of T lymphotropic Herpesvirus saimiri (HVS is targeted to lipid rafts in T cells and downregulates TCR and CD4 surface expression. Here, we report that the membrane-proximal amphipathic helix preceding Tip's transmembrane (TM domain mediates lipid raft localization and membrane deformation. In turn, this motif directs Tip's lysosomal trafficking and selective TCR downregulation. The amphipathic helix binds to the negatively charged lipids and induces liposome tubulation, the TM domain mediates oligomerization, and cooperation of the membrane-proximal helix with the TM domain is sufficient for localization to lipid rafts and lysosomal compartments, especially the mutivesicular bodies. These findings suggest that the membrane-proximal amphipathic helix and TM domain provide HVS Tip with the unique ability to deform the cellular membranes in lipid rafts and to downregulate TCRs potentially through MVB formation.

  8. Anti-plasmodial action of de novo-designed, cationic, lysine-branched, amphipathic, helical peptides

    Directory of Open Access Journals (Sweden)

    Kaushik Naveen K

    2012-08-01

    Full Text Available Abstract Background A lack of vaccine and rampant drug resistance demands new anti-malarials. Methods In vitro blood stage anti-plasmodial properties of several de novo-designed, chemically synthesized, cationic, amphipathic, helical, antibiotic peptides were examined against Plasmodium falciparum using SYBR Green assay. Mechanistic details of anti-plasmodial action were examined by optical/fluorescence microscopy and FACS analysis. Results Unlike the monomeric decapeptides {(Ac-GXRKXHKXWA-NH2 (X = F,ΔF (Fm, ΔFm IC50 >100 μM}, the lysine-branched,dimeric versions showed far greater potency {IC50 (μM Fd 1.5 , ΔFd 1.39}. The more helical and proteolytically stable ΔFd was studied for mechanistic details. ΔFq, a K-K2 dendrimer of ΔFm and (ΔFm2 a linear dimer of ΔFm showed IC50 (μM of 0.25 and 2.4 respectively. The healthy/infected red cell selectivity indices were >35 (ΔFd, >20 (ΔFm2 and 10 (ΔFq. FITC-ΔFd showed rapid and selective accumulation in parasitized red cells. Overlaying DAPI and FITC florescence suggested that ΔFd binds DNA. Trophozoites and schizonts incubated with ΔFd (2.5 μM egressed anomalously and Band-3 immunostaining revealed them not to be associated with RBC membrane. Prematurely egressed merozoites from peptide-treated cultures were found to be invasion incompetent. Conclusion Good selectivity (>35, good resistance index (1.1 and low cytotoxicity indicate the promise of ΔFd against malaria.

  9. Nanoshaving and Nanografting of Water Soluble Polymers on Glass and Silicon Dioxide Surfaces with Applications to DNA Localization

    Science.gov (United States)

    Davis, Brian; Conley, Hiram; Ochoa, Rosie; Hurd, Katie; Linford, Matthew R.; Davis, Robert C.

    2008-10-01

    Chemical surface patterning at the nanoscale is a critical component of chemically directed assembly of nanoscale devices or sensitive biological molecules onto surfaces. Here we present a scanning probe lithography technique that allows for patterning of aqueous polymers on glass or silicon dioxide surfaces. The surfaces were functionalized by covalently bonding a silane monolayer with a known surface charge to either a glass slide or a silicon wafer. A polymer layer less then 2 nm in thickness was electrostatically bound to the silane layer, passivating the functionalized surface. An Atomic Force Microscope (AFM) probe was used to remove a portion of the polymer layer, exposing the functional silane layer underneath. Employing this method we made chemically active submicron regions. These regions were backfilled with a fluorescent polymer and Lambda-DNA. Chemical differentiation was verified through tapping mode AFM and optical fluorescent microscopy. Lines with a pitch as small as 20nm were observed with AFM height and phase mode data.

  10. Zwitterionic peptide anchored to conducting polymer PEDOT for the development of antifouling and ultrasensitive electrochemical DNA sensor.

    Science.gov (United States)

    Wang, Guixiang; Han, Rui; Su, Xiaoli; Li, Yinan; Xu, Guiyun; Luo, Xiliang

    2017-06-15

    Zwitterionic peptides were anchored to a conducting polymer of citrate doped poly(3,4-ethylenedioxythiophene) (PEDOT) via the nickel cation coordination, and the obtained peptide modified PEDOT, with excellent antifouling ability and good conductivity, was further used for the immobilization of a DNA probe to construct an electrochemical biosensor for the breast cancer marker BRCA1. The DNA biosensor was highly sensitive (with detection limit of 0.03fM) and selective, and it was able to detect BRCA1 in 5% (v/v) human plasma with satisfying accuracy and low fouling. The marriage of antifouling and biocompatible peptides with conducting polymers opened a new avenue to construct electrochemical biosensors capable of assaying targets in complex biological media with high sensitivity and without biofouling. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Precise Coating of a Wide Range of DNA Templates by a Protein Polymer with a DNA Binding Domain

    NARCIS (Netherlands)

    Hernandez-Garcia, Armando; Estrich, Nicole A.; Werten, Marc W.T.; Maarel, van der Johan R.C.; Labean, Thomas H.; Wolf, de Frits A.; Cohen Stuart, Martien A.; Vries, de Renko

    2017-01-01

    Emerging DNA-based nanotechnologies would benefit from the ability to modulate the properties (e.g., solubility, melting temperature, chemical stability) of diverse DNA templates (single molecules or origami nanostructures) through controlled, self-assembling coatings. We here introduce a DNA

  12. Rectangular coordination polymer nanoplates: large-scale, rapid synthesis and their application as a fluorescent sensing platform for DNA detection.

    Directory of Open Access Journals (Sweden)

    Yingwei Zhang

    Full Text Available In this paper, we report on the large-scale, rapid synthesis of uniform rectangular coordination polymer nanoplates (RCPNs assembled from Cu(II and 4,4'-bipyridine for the first time. We further demonstrate that such RCPNs can be used as a very effective fluorescent sensing platform for multiple DNA detection with a detection limit as low as 30 pM and a high selectivity down to single-base mismatch. The DNA detection is accomplished by the following two steps: (1 RCPN binds dye-labeled single-stranded DNA (ssDNA probe, which brings dye and RCPN into close proximity, leading to fluorescence quenching; (2 Specific hybridization of the probe with its target generates a double-stranded DNA (dsDNA which detaches from RCPN, leading to fluorescence recovery. It suggests that this sensing system can well discriminate complementary and mismatched DNA sequences. The exact mechanism of fluorescence quenching involved is elucidated experimentally and its use in a human blood serum system is also demonstrated successfully.

  13. Release of DNA from polyelectrolyte multilayers fabricated using 'charge-shifting' cationic polymers: tunable temporal control and sequential, multi-agent release.

    Science.gov (United States)

    Sun, Bin; Lynn, David M

    2010-11-20

    We report an approach to the design of multilayered polyelectrolyte thin films (or 'polyelectrolyte multilayers', PEMs) that can be used to provide tunable control over the release of plasmid DNA (or multiple different DNA constructs) from film-coated surfaces. Our approach is based upon methods for the layer-by-layer assembly of DNA-containing thin films, and exploits the properties of a new class of cationic 'charge-shifting' polymers (amine functionalized polymers that undergo gradual changes in net charge upon side chain ester hydrolysis) to provide control over the rates at which these films erode and release DNA. We synthesized two 'charge-shifting' polymers (polymers 1 and 2) containing different side chain structures by ring-opening reactions of poly(2-alkenyl azlactone)s with two different tertiary amine functionalized alcohols (3-dimethylamino-1-propanol and 2-dimethylaminoethanol, respectively). Subsequent characterization revealed large changes in the rates of side chain ester hydrolysis for these two polymers; whereas the half-life for the hydrolysis of the esters in polymer 1 was ~200 days, the half-life for polymer 2 was ~6 days. We demonstrate that these large differences in side chain hydrolysis make possible the design of PEMs that erode and promote the surface-mediated release of DNA either rapidly (e.g., over ~3 days for films fabricated using polymer 2) or slowly (e.g., over ~1 month for films fabricated using polymer 1). We demonstrate further that it is possible to design films with release profiles that are intermediate to these two extremes by fabricating films using solutions containing different mixtures of these two polymers. This approach can thus expand the usefulness of these two polymers and achieve a broader range of DNA release profiles without the need to synthesize polymers with new structures or properties. Finally, we demonstrate that polymers 1 and 2 can be used to fabricate multilayered films with hierarchical structures that

  14. Amphipathic motifs in BAR domains are essential for membrane curvature sensing

    DEFF Research Database (Denmark)

    Bhatia, Vikram K; Madsen, Kenneth L; Bolinger, Pierre-Yves

    2009-01-01

    BAR (Bin/Amphiphysin/Rvs) domains and amphipathic alpha-helices (AHs) are believed to be sensors of membrane curvature thus facilitating the assembly of protein complexes on curved membranes. Here, we used quantitative fluorescence microscopy to compare the binding of both motifs on single...... nanosized liposomes of different diameters and therefore membrane curvature. Characterization of members of the three BAR domain families showed surprisingly that the crescent-shaped BAR dimer with its positively charged concave face is not able to sense membrane curvature. Mutagenesis on BAR domains showed...... that membrane curvature sensing critically depends on the N-terminal AH and furthermore that BAR domains sense membrane curvature through hydrophobic insertion in lipid packing defects and not through electrostatics. Consequently, amphipathic motifs, such as AHs, that are often associated with BAR domains...

  15. One-step polymer surface modification for minimizing drug, protein, and DNA adsorption in microanalytical systems

    DEFF Research Database (Denmark)

    Larsen, Esben Kjær Unmack; Larsen, Niels Bent

    2013-01-01

    The non-specific adsorption of dissolved analytes strongly reduces the sensitivity and reliability in polymer microanalytical systems. Here, a one-step aqueous phase procedure modifies polymer material surfaces to strongly reduce their non-specific adsorption of a broad range of organic analytes ...

  16. Highly Sensitive Polymer-based Cantilever-sensors for DNA Detection

    DEFF Research Database (Denmark)

    Gomez, Montserrat; Nordström, Maria; Alvarez, M.

    2005-01-01

    We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel...... polymer material SU-8. The low Young's modulus of the polymer, 40 times lower than that of silicon, enables to improve the sensitivity of the sensor device for target detection. The mechanical properties of SU-8 cantilevers, such as spring constant, resonant frequency and quality factor are characterized...

  17. Carbon nanotube/polymer composite electrodes for flexible, attachable electrochemical DNA sensors.

    Science.gov (United States)

    Li, Jianfeng; Lee, Eun-Cheol

    2015-09-15

    All-solution-processed, easily-made, flexible multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS)-based electrodes were fabricated and used for electrochemical DNA sensors. These electrodes could serve as a recognition layer for DNA, without any surface modification, through π-π interactions between the MWCNTs and DNA, greatly simplifying the fabrication process for DNA sensors. The electrodes were directly connected to an electrochemical analyzer in the differential pulse voltammetry (DPV) and cyclic voltammetry (CV) measurements, where methylene blue was used as a redox indicator. Since neither functional groups nor probe DNA were immobilized on the surfaces of the electrodes, the sensor can be easily regenerated by washing these electrodes with water. The limit of detection was found to be 1.3 × 10(2)pM (S/N=3), with good DNA sequence differentiation ability. Fast fabrication of a DNA sensor was also achieved by cutting and attaching the MWCNT-PDMS composite electrodes at an analyte solution-containable region. Our results pave the way for developing user-fabricated easily attached DNA sensors at low costs. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. The synthesis of amphipathic prodrugs of 1,2-diol drugs with saccharide conjugates by high regioselective enzymatic protocol.

    Science.gov (United States)

    Quan, Jing; Chen, Zhichun; Han, Chengyou; Lin, Xianfu

    2007-02-15

    A facile, high regioselective enzymatic synthesis approach for the preparation of amphipathic prodrugs with saccharides of mephenesin and chlorphenesin was developed. Firstly, transesterification of two drugs with divinyl dicarboxylates with different carbon chain length was performed under the catalysis of Candida antarctica lipase acrylic resin and Lipozyme in anhydrous acetone at 50 degrees C, respectively. A series of lipophilic derivatives with vinyl groups of mephenesin and chlorphenesin were prepared. The influences of different organic solvents, enzyme sources, reaction time, and the acylation reagents on the synthesis of vinyl esters were investigated. And then, protease-catalyzed high regioselective acylation of D-glucose and D-mannose with vinyl esters of mephenesin and chlorphenesin gave drug-saccharide derivatives in good yields. The studies of lipophilicity and hydrolysis in vitro of prodrugs verified that drug-saccharide derivatives had amphipathic properties, and both lipophilic and amphipathic drug derivatives had obvious controlled release characteristics.

  19. Lipid Binding of the Amphipathic Helix Serving as Membrane Anchor of Pestivirus Glycoprotein Erns.

    Science.gov (United States)

    Aberle, Daniel; Oetter, Kay-Marcus; Meyers, Gregor

    2015-01-01

    Pestiviruses express a peculiar protein named Erns representing envelope glycoprotein and RNase, which is important for control of the innate immune response and persistent infection. The latter functions are connected with secretion of a certain amount of Erns from the infected cell. Retention/secretion of Erns is most likely controlled by its unusual membrane anchor, a long amphipathic helix attached in plane to the membrane. Here we present results of experiments conducted with a lipid vesicle sedimentation assay able to separate lipid-bound from unbound protein dissolved in the water phase. Using this technique we show that a protein composed of tag sequences and the carboxyterminal 65 residues of Erns binds specifically to membrane vesicles with a clear preference for compositions containing negatively charged lipids. Mutations disturbing the helical folding and/or amphipathic character of the anchor as well as diverse truncations and exchange of amino acids important for intracellular retention of Erns had no or only small effects on the proteins membrane binding. This result contrasts the dramatically increased secretion rates observed for Erns proteins with equivalent mutations within cells. Accordingly, the ratio of secreted versus cell retained Erns is not determined by the lipid affinity of the membrane anchor.

  20. Lipid Binding of the Amphipathic Helix Serving as Membrane Anchor of Pestivirus Glycoprotein Erns.

    Directory of Open Access Journals (Sweden)

    Daniel Aberle

    Full Text Available Pestiviruses express a peculiar protein named Erns representing envelope glycoprotein and RNase, which is important for control of the innate immune response and persistent infection. The latter functions are connected with secretion of a certain amount of Erns from the infected cell. Retention/secretion of Erns is most likely controlled by its unusual membrane anchor, a long amphipathic helix attached in plane to the membrane. Here we present results of experiments conducted with a lipid vesicle sedimentation assay able to separate lipid-bound from unbound protein dissolved in the water phase. Using this technique we show that a protein composed of tag sequences and the carboxyterminal 65 residues of Erns binds specifically to membrane vesicles with a clear preference for compositions containing negatively charged lipids. Mutations disturbing the helical folding and/or amphipathic character of the anchor as well as diverse truncations and exchange of amino acids important for intracellular retention of Erns had no or only small effects on the proteins membrane binding. This result contrasts the dramatically increased secretion rates observed for Erns proteins with equivalent mutations within cells. Accordingly, the ratio of secreted versus cell retained Erns is not determined by the lipid affinity of the membrane anchor.

  1. Light-switchable polymer from cationic to zwitterionic form: synthesis, characterization, and interactions with DNA and bacterial cells.

    Science.gov (United States)

    Sobolčiak, Patrik; Spírek, Mário; Katrlík, Jaroslav; Gemeiner, Peter; Lacík, Igor; Kasák, Peter

    2013-04-25

    A novel cationic polymer poly(N,N-dimethyl-N-[3-(methacroylamino) propyl]-N-[2-[(2-nitrophenyl)methoxy]-2-oxo-ethyl]ammonium chloride) is synthesized by free-radical polymerization of N-[3-(dimethylamino)propyl] methacrylamide and subsequent quaternization with o-nitrobenzyl 2-chloroacetate. The photolabile o-nitrobenzyl carboxymethyl pendant moiety is transformed to the zwitterionic carboxybetaine form upon the irradiation at 365 nm. This feature is used to condense and, upon the light irradiation, to release double-strand DNA tested by gel electrophoresis and surface plasmon resonance experiments as well as to switch the antibacterial activity to non-toxic character demonstrated for Escherichia coli bacterial cells in solution and at the surface using the self-assembled monolayers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Stretching DNA in polymer nanochannels fabricated by thermal imprint in PMMA

    DEFF Research Database (Denmark)

    Thamdrup, Lasse Højlund; Klukowska, A.; Kristensen, Anders

    2008-01-01

    . The stamp is compatible with molecular vapor deposition ( MVD), used for applying a durable chlorosilane based antistiction coating, and allows for imprint up to a temperature of 270 degrees C. The extension of YOYO-1 stained T4 GT7 bacteriophage DNA inside the PMMA nanochannels has been experimentally...

  3. A polymer, random walk model for the size-distribution of large DNA fragments after high linear energy transfer radiation

    Science.gov (United States)

    Ponomarev, A. L.; Brenner, D.; Hlatky, L. R.; Sachs, R. K.

    2000-01-01

    DNA double-strand breaks (DSBs) produced by densely ionizing radiation are not located randomly in the genome: recent data indicate DSB clustering along chromosomes. Stochastic DSB clustering at large scales, from > 100 Mbp down to simulations and analytic equations. A random-walk, coarse-grained polymer model for chromatin is combined with a simple track structure model in Monte Carlo software called DNAbreak and is applied to data on alpha-particle irradiation of V-79 cells. The chromatin model neglects molecular details but systematically incorporates an increase in average spatial separation between two DNA loci as the number of base-pairs between the loci increases. Fragment-size distributions obtained using DNAbreak match data on large fragments about as well as distributions previously obtained with a less mechanistic approach. Dose-response relations, linear at small doses of high linear energy transfer (LET) radiation, are obtained. They are found to be non-linear when the dose becomes so large that there is a significant probability of overlapping or close juxtaposition, along one chromosome, for different DSB clusters from different tracks. The non-linearity is more evident for large fragments than for small. The DNAbreak results furnish an example of the RLC (randomly located clusters) analytic formalism, which generalizes the broken-stick fragment-size distribution of the random-breakage model that is often applied to low-LET data.

  4. A New FRET-Based Sensitive DNA Sensor for Medical Diagnostics using PNA Probe and Water-Soluble Blue Light Emitting Polymer

    Directory of Open Access Journals (Sweden)

    Nidhi Mathur

    2008-01-01

    Full Text Available A reliable, fast, and low-cost biosensor for medical diagnostics using DNA sequence detection has been developed and tested for the detection of the bacterium “Bacillus anthracis.” In this sensor, Poly [9,9-di (6,6′- N, N′ trimethylammonium hexylfluorenyl-2, 7-diyl-alt-co- (1,4-phenylene] dibromide salt (PFP has been taken as cationic conjugated polymer (CCP and PNA attached with fluorescein dye (PNAC∗ as a probe. The basic principle of this sensor is that when a PNAC∗ probe is hybridized with a single strand DNA (ssDNA having complementary sequence, Forster resonance energy transfer (FRET may take place from PFP to the PNAC∗/DNA complex. If the FRET is efficient, the photoluminescence from the PFP will be highly quenched and that from PNAC∗ will be enhanced. On the other hand, if the DNA sequence is noncomplementary to PNA, FRET will not occur.

  5. BAR domains, amphipathic helices and membrane-anchored proteins use the same mechanism to sense membrane curvature

    DEFF Research Database (Denmark)

    Madsen, Kenneth Lindegaard; Bhatia, V K; Gether, U

    2010-01-01

    /ensemble liposome samples of different mean diameter. Next, we describe two different MCS protein motifs (amphipathic helices and BAR domains) and suggest that in both cases curvature sensitive membrane binding results from asymmetric insertion of hydrophobic amino acids in the lipid membrane. This mechanism can...

  6. Amphipathic lignin derivatives to accelerate simultaneous saccharification and fermentation of unbleached softwood pulp for bioethanol production.

    Science.gov (United States)

    Cheng, Ningning; Yamamoto, Yoko; Koda, Keiichi; Tamai, Yutaka; Uraki, Yasumitsu

    2014-12-01

    Amphipathic lignin derivatives (A-LDs) were already demonstrated to improve enzymatic saccharification of lignocellulose. Based on this knowledge, two kinds of A-LDs prepared from black liquor of soda pulping of Japanese cedar were applied to a fed-batch simultaneous saccharification and fermentation (SSF) process for unbleached soda pulp of Japanese cedar to produce bioethanol. Both lignin derivatives slightly accelerated yeast fermentation of glucose but not inhibited it. In addition, ethanol yields based on the theoretical maximum ethanol production in the fed-batch SSF process was increased from 49% without A-LDs to 64% in the presence of A-LDs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. The mismatch repair and meiotic recombination endonuclease Mlh1-Mlh3 is activated by polymer formation and can cleave DNA substrates in trans.

    Science.gov (United States)

    Manhart, Carol M; Ni, Xiaodan; White, Martin A; Ortega, Joaquin; Surtees, Jennifer A; Alani, Eric

    2017-04-01

    Crossing over between homologs is initiated in meiotic prophase by the formation of DNA double-strand breaks that occur throughout the genome. In the major interference-responsive crossover pathway in baker's yeast, these breaks are resected to form 3' single-strand tails that participate in a homology search, ultimately forming double Holliday junctions (dHJs) that primarily include both homologs. These dHJs are resolved by endonuclease activity to form exclusively crossovers, which are critical for proper homolog segregation in Meiosis I. Recent genetic, biochemical, and molecular studies in yeast are consistent with the hypothesis of Mlh1-Mlh3 DNA mismatch repair complex acting as the major endonuclease activity that resolves dHJs into crossovers. However, the mechanism by which the Mlh1-Mlh3 endonuclease is activated is unknown. Here, we provide evidence that Mlh1-Mlh3 does not behave like a structure-specific endonuclease but forms polymers required to generate nicks in DNA. This conclusion is supported by DNA binding studies performed with different-sized substrates that contain or lack polymerization barriers and endonuclease assays performed with varying ratios of endonuclease-deficient and endonuclease-proficient Mlh1-Mlh3. In addition, Mlh1-Mlh3 can generate religatable double-strand breaks and form an active nucleoprotein complex that can nick DNA substrates in trans. Together these observations argue that Mlh1-Mlh3 may not act like a canonical, RuvC-like Holliday junction resolvase and support a novel model in which Mlh1-Mlh3 is loaded onto DNA to form an activated polymer that cleaves DNA.

  8. Deep Subseafloor Fungi as an Untapped Reservoir of Amphipathic Antimicrobial Compounds.

    Science.gov (United States)

    Navarri, Marion; Jégou, Camille; Meslet-Cladière, Laurence; Brillet, Benjamin; Barbier, Georges; Burgaud, Gaëtan; Fleury, Yannick

    2016-03-10

    The evolving global threat of antimicrobial resistance requires a deep renewal of the antibiotic arsenal including the isolation and characterization of new drugs. Underexplored marine ecosystems may represent an untapped reservoir of novel bioactive molecules. Deep-sea fungi isolated from a record-depth sediment core of almost 2000 m below the seafloor were investigated for antimicrobial activities. This antimicrobial screening, using 16 microbial targets, revealed 33% of filamentous fungi synthesizing bioactive compounds with activities against pathogenic bacteria and fungi. Interestingly, occurrence of antimicrobial producing isolates was well correlated with the complexity of the habitat (in term of microbial richness), as higher antimicrobial activities were obtained at specific layers of the sediment core. It clearly highlights complex deep-sea habitats as chemical battlefields where synthesis of numerous bioactive compounds appears critical for microbial competition. The six most promising deep subseafloor fungal isolates were selected for the production and extraction of bioactive compounds. Depending on the fungal isolates, antimicrobial compounds were only biosynthesized in semi-liquid or solid-state conditions as no antimicrobial activities were ever detected using liquid fermentation. An exception was made for one fungal isolate, and the extraction procedure designed to extract amphipathic compounds was successful and highlighted the amphiphilic profile of the bioactive metabolites.

  9. Amphipaths Differentially Modulate Membrane Surface Deformation in Rat Peritoneal Mast Cells During Exocytosis

    Directory of Open Access Journals (Sweden)

    Itsuro Kazama

    2013-04-01

    Full Text Available Background/Aims: Salicylate and chlorpromazine exert differential effects on the chemokine release from mast cells. Since these drugs are amphiphilic and preferentially partitioned into the lipid bilayers of the plasma membranes, they would induce some morphological changes in mast cells and thus affect the process of exocytosis. Methods: Employing the standard patch-clamp whole-cell recording technique, we examined the effects of salicylate and chlorpromazine on the membrane capacitance (Cm during exocytosis in rat peritoneal mast cells. Using confocal imaging of a water-soluble fluorescent dye, lucifer yellow, we also examined their effects on plasma membrane deformation of the cells. Results: Salicylate dramatically accelerated the GTP-γ-S-induced increase in the Cm immediately after its application, whereas chlorpromazine significantly suppressed the increase. Treatment with salicylate increased the trapping of the dye on the cell surface, while treatment with chlorpromazine completely washed it out, indicating that both drugs induced membrane surface deformation in mast cells. Conclusion: This study demonstrated for the first time that membrane amphipaths, such as salicylate and chlorpromazine, may oppositely modulate the process of exocytosis in mast cells, as detected by the changes in the Cm. The plasma membrane deformation induced by the drugs was thought to be responsible for their differential effects.

  10. Rigid amphipathic fusion inhibitors demonstrate antiviral activity against African swine fever virus.

    Science.gov (United States)

    Hakobyan, Astghik; Galindo, Inmaculada; Nañez, Almudena; Arabyan, Erik; Karalyan, Zaven; Chistov, Alexey A; Streshnev, Philipp P; Korshun, Vladimir A; Alonso, Covadonga; Zakaryan, Hovakim

    2018-01-01

    Rigid amphipathic fusion inhibitors (RAFIs) are a family of nucleoside derivatives that inhibit the infectivity of several enveloped viruses by interacting with virion envelope lipids and inhibiting fusion between viral and cellular membranes. Here we tested the antiviral activity of two RAFIs, 5-(Perylen-3-ylethynyl)-arabino-uridine (aUY11) and 5-(Perylen-3-ylethynyl)uracil-1-acetic acid (cm1UY11) against African swine fever virus (ASFV), for which no effective vaccine is available. Both compounds displayed a potent, dose-dependent inhibitory effect on ASFV infection in Vero cells. The major antiviral effect was observed when aUY11 and cm1UY11 were added at early stages of infection and maintained during the complete viral cycle. Furthermore, virucidal assay revealed a significant extracellular anti-ASFV activity for both compounds. We also found decrease in the synthesis of early and late viral proteins in Vero cells treated with cm1UY11. Finally, the inhibitory effect of aUY11 and cm1UY11 on ASFV infection in porcine alveolar macrophages was confirmed. Overall, our study has identified novel anti-ASFV compounds with potential for future therapeutic developments.

  11. Optimization of simultaneous saccharification and fermentation conditions with amphipathic lignin derivatives for concentrated bioethanol production.

    Science.gov (United States)

    Cheng, Ningning; Koda, Keiichi; Tamai, Yutaka; Yamamoto, Yoko; Takasuka, Taichi E; Uraki, Yasumitsu

    2017-05-01

    Amphipathic lignin derivatives (A-LDs) prepared from the black liquor of soda pulping of Japanese cedar are strong accelerators for bioethanol production under a fed-batch simultaneous enzymatic saccharification and fermentation (SSF) process. To improve the bioethanol production concentration, conditions such as reaction temperature, stirring program, and A-LDs loadings were optimized in both small scale and large scale fed-batch SSF. The fed-batch SSF in the presence of 3.0g/L A-LDs at 38°C gave the maximum ethanol production and a high enzyme recovery rate. Furthermore, a jar-fermenter equipped with a powerful mechanical stirrer was designed for 1.5L-scale fed-batch SSF to achieve rigorous mixing during high substrate loading. Finally, the 1.5L fed-batch SSF with a substrate loading of 30% (w/v) produced a high ethanol concentration of 87.9g/L in the presence of A-LDs under optimized conditions. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. [Verification of a decrease in the rigidity of the phage lambda DNA polymeric chain in low ionic strength aqueous solutions by testing the polymer-polymer interlink interactions].

    Science.gov (United States)

    Arutiunian, A V; Ivanova, M A; Kurliand, D I; Kapshin, Iu S; Landa, S B; Poshekhonov, S T; Drobchenko, E A; Shevelev, I V

    2011-01-01

    Changes in the rigidity of the polymetric chain of phage lambda double-strand DNA have been studied by laser correlation spectroscopy. It was shown that, as the ionic strength increases, the effect of the screening of the hydrodynamic interaction of the links of the polymeric chain specific for polymeric coils arises in a DNA solution. It is assumed that the screening occurs when the threshold of the overlapping of DNA coils is achieved. The overlapping of coils is the result of a previously observed significant rise of DNA coil size from abnormally small DNA coils in low ionic strength buffers (about 10(-2) M Na+ or less) to maximum possible large coils in the 5SSC and 5SSC-like buffers. Further analysis of the far interlink interactions in linear lambda phage DNA coils in similar buffers at pH 7 and 4 confirms the earlier proposal about the role of H+ ions in the appearance of abnormally small DNA coils. The abnormal decrease in the DNA coil size in low ionic strength buffers is not a specific feature of lambda phage DNA only.

  13. In situ analysis of Bacillus licheniformis biofilms: amyloid-like polymers and eDNA are involved in the adherence and aggregation of the extracellular matrix.

    Science.gov (United States)

    Randrianjatovo-Gbalou, I; Rouquette, P; Lefebvre, D; Girbal-Neuhauser, E; Marcato-Romain, C-E

    2017-05-01

    This study attempts to determine which of the exopolymeric substances are involved in the adherence and aggregation of a Bacillus licheniformis biofilm. The involvement of extracellular proteins and eDNA were particularly investigated using DNase and proteinase K treatment. The permeability of the biofilms increased fivefold after DNase I treatment. The quantification of the matrix components showed that, irrespective to the enzyme tested, eDNA and amyloid-like polymers were removed simultaneously. Size-exclusion chromatography analyses supported these observations and revealed the presence of associated nucleic acid and protein complexes in the biofilm lysates. These data suggest that some extracellular DNA and amyloid-like proteins were closely interlaced within the matrix. Finally, confocal laser scanning microscopy imaging gave supplementary clues about the 3D organization of the biofilms, confirming that eDNA and exoproteins were essentially layered under and around the bacterial cells, whereas the amyloid-like fractions were homogeneously distributed within the matrix. These results confirm that some DNA-amyloid complexes play a key role in the modulation of the mechanical resistance of B. licheniformis biofilms. The study highlights the need to consider the whole structure of biofilms and to target the interactions between matrix components. A better understanding of B. licheniformis biofilm physiology and the structural organization of the matrix will strengthen strategies of biofilm control. © 2017 The Society for Applied Microbiology.

  14. Green synthesis of amphipathic graphene aerogel constructed by using the framework of polymer-surfactant complex for water remediation

    Science.gov (United States)

    Cao, Jingjing; Wang, Ziyuan; Yang, Xianhou; Tu, Jing; Wu, Ronglan; Wang, Wei

    2018-06-01

    Graphene aerogels have been extensively studied in water treatment and oil remediation. We report a mild and green method to prepare a 3D-columnar graphene aerogel. The aerogel was synthesized by using polyvinyl alcohol (PVA) and stearic acid (SA) as crosslinking agents to construct a framework of reduced graphene oxide (RGO). The interaction between PVA, SA, and stacked RGO sheets created a mechanically very robust aerogel. The aerogel possesses ultra-light performance with the destiny ranging from 4.9 to 10 mg cm-3. The aerogel also demonstrated ultrafast oil absorption, good fire-resistance, and excellent mechanical properties. The adsorptive capacities are in the range of 105-250 times of its original weight for various organic liquids after the absorption. The aerogel also exhibited a strong durability and reusability, and after ten cycles of absorbing-squeezing, the adsorptive capacity is nearly unchanged, indicating potential application in practical oil remediation.

  15. Fluorescent strategy based on cationic conjugated polymer fluorescence resonance energy transfer for the quantification of 5-(hydroxymethyl)cytosine in genomic DNA.

    Science.gov (United States)

    Hong, Tingting; Wang, Tianlu; Guo, Pu; Xing, Xiwen; Ding, Fei; Chen, Yuqi; Wu, Jinjun; Ma, Jingwei; Wu, Fan; Zhou, Xiang

    2013-11-19

    DNA methylation is dynamically reprogrammed during early embryonic development in mammals. It can be explained partially by the discovery of 5-(hydroxymethyl)cytosine (5-hmC), 5-formylcytosine (5-fC), and 5-carboxylcytosine (5-caC), which are identified as key players involved in both active and passive demethylation pathways. As one of the ten-eleven translocation oxidation products, 5-hmC was found relatively abundant in neuron cells and embryonic stem cells. Herein we report a new method for 5-hmC quantification in genomic DNA based on CCP-FRET (cationic conjugated polymers act as the energy donor and induce fluorescence resonance energy transfer) assay combined with KRuO4 oxidation. 5-hmC in genomic DNA can be selectively transformed into 5-fC by the oxidation of KRuO4 and then labeled with hydroxylamine-BODIPY (BODIPY = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) fluorophore through the reaction between 5-fC and hydroxylamine-BODIPY. After the fluorescently labeled DNA was captured by CCP through electrostatic interactions, a significant FRET between CCP and hydroxylamine-BODIPY fluorophore was observed. This CCP-FRET-based assay benefits from light-harvesting, large Stokes shift, and optical signal amplification properties of the CCP. Furthermore, this CCP-FRET-based assay was quite successfully demonstrated for the 5-hmC quantification in three types of cells (mESc, HeLa, HEK 293T), providing a much more convenient choice for 5-hmC quantification in genomic DNA.

  16. DNA barcoding via counterstaining with AT/GC sensitive ligands in injection-molded all-polymer nanochannel devices

    DEFF Research Database (Denmark)

    Østergaard, Peter Friis; Matteucci, Marco; Reisner, Walter

    2013-01-01

    Nanochannel technology, coupled with a suitable DNA labeling chemistry, is a powerful approach for performing high-throughput single-molecule mapping of genomes. Yet so far nanochannel technology has remained inaccessible to the broader research community due to high fabrication cost and/or requi......Nanochannel technology, coupled with a suitable DNA labeling chemistry, is a powerful approach for performing high-throughput single-molecule mapping of genomes. Yet so far nanochannel technology has remained inaccessible to the broader research community due to high fabrication cost and...... AT and GC variation along DNA sequences....

  17. Fish DNA-modified clays: Towards highly flame retardant polymer nanocomposite with improved interfacial and mechanical performance

    Science.gov (United States)

    Zabihi, Omid; Ahmadi, Mojtaba; Khayyam, Hamid; Naebe, Minoo

    2016-12-01

    Deoxyribonucleic Acid (DNA) has been recently found to be an efficient renewable and environmentally-friendly flame retardant. In this work, for the first time, we have used waste DNA from fishing industry to modify clay structure in order to increase the clay interactions with epoxy resin and take benefit of its additional thermal property effect on thermo-physical properties of epoxy-clay nanocomposites. Intercalation of DNA within the clay layers was accomplished in a one-step approach confirmed by FT-IR, XPS, TGA, and XRD analyses, indicating that d-space of clay layers was expanded from ~1.2 nm for pristine clay to ~1.9 nm for clay modified with DNA (d-clay). Compared to epoxy nanocomposite containing 2.5%wt of Nanomer I.28E organoclay (m-clay), it was found that at 2.5%wt d-clay loading, significant enhancements of ~14%, ~6% and ~26% in tensile strength, tensile modulus, and fracture toughness of epoxy nanocomposite can be achieved, respectively. Effect of DNA as clay modifier on thermal performance of epoxy nanocomposite containing 2.5%wt d-clay was evaluated using TGA and cone calorimetry analysis, revealing significant decreases of ~4000 kJ/m2 and ~78 kW/m2 in total heat release and peak of heat release rate, respectively, in comparison to that containing 2.5%wt of m-clay.

  18. Simultaneous membrane interaction of amphipathic peptide monomers, self-aggregates and cargo complexes detected by fluorescence correlation spectroscopy.

    Science.gov (United States)

    Vasconcelos, Luís; Lehto, Tõnis; Madani, Fatemeh; Radoi, Vlad; Hällbrink, Mattias; Vukojević, Vladana; Langel, Ülo

    2018-02-01

    Peptides able to translocate cell membranes while carrying macromolecular cargo, as cell-penetrating peptides (CPPs), can contribute to the field of drug delivery by enabling the transport of otherwise membrane impermeable molecules. Formation of non-covalent complexes between amphipathic peptides and oligonucleotides is driven by electrostatic and hydrophobic interactions. Here we investigate and quantify the coexistence of distinct molecular species in multiple equilibria, namely peptide monomer, peptide self-aggregates and peptide/oligonucleotide complexes. As a model for the complexes, we used a stearylated peptide from the PepFect family, PF14 and siRNA. PF14 has a cationic part and a lipid part, resembling some characteristics of cationic lipids. Fluorescence correlation spectroscopy (FCS) and fluorescence cross-correlation spectroscopy (FCCS) were used to detect distinct molecular entities in solution and at the plasma membrane of live cells. For that, we labeled the peptide with carboxyrhodamine 6G and the siRNA with Cyanine 5. We were able to detect fluorescent entities with diffusional properties characteristic of the peptide monomer as well as of peptide aggregates and peptide/oligonucleotide complexes. Strategies to avoid peptide adsorption to solid surfaces and self-aggregation were developed and allowed successful FCS measurements in solution and at the plasma membrane. The ratio between the detected molecular species was found to vary with pH, peptide concentration and the proximity to the plasma membrane. The present results suggest that the diverse cellular uptake mechanisms, often reported for amphipathic CPPs, might result from the synergistic effect of peptide monomers, self-aggregates and cargo complexes, distributed unevenly at the plasma membrane. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Comparative mode of action of novel hybrid peptide CS-1a and its rearranged amphipathic analogue CS-2a.

    Science.gov (United States)

    Joshi, Seema; Bisht, Gopal S; Rawat, Diwan S; Maiti, Souvik; Pasha, Santosh

    2012-10-01

    Cell selective, naturally occurring, host defence cationic peptides present a good template for the design of novel peptides with the aim of achieving a short length with improved antimicrobial potency and selectivity. A novel, short peptide CS-1a (14 residues) was derived using a sequence hybridization approach on sarcotoxin I (39 residues) and cecropin B (35 residues). The sequence of CS-1a was rearranged to enhance amphipathicity with the help of a Schiffer-Edmundson diagram to obtain CS-2a. Both peptides showed good antibacterial activity in the concentration range 4-16 μg·mL(-1) against susceptible as well as drug-resistant bacterial strains, including the clinically relevant pathogens Acenatobacter sp. and methicillin-resistant Staphylococcus aureus. The major thrust of these peptides is their nonhaemolytic activity against human red blood cells up to a high concentration of 512 μg·mL(-1). Compared to CS-1a, amphipathic peptide CS-2a showed a more pronounced α-helical conformation, along with a better membrane insertion depth in bacterial mimic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) small unilamellar vesicles. With equivalent lipid-binding affinity, the two peptides assumed different pathways of membrane disruption, as demonstrated by calcein leakage and the results of transmission electron microscopy on model bacterial mimic large unilamellar vesicles. Extending the work from model membranes to intact Escherichia coli cells, differences in membrane perturbation were visible in microscopic images of peptide-treated E. coli. The present study describes two novel short peptides with potent activity, cell selectivity and divergent modes of action that will aid in the future design of peptides with better therapeutic potential. © 2012 The Authors Journal compilation © 2012 FEBS.

  20. Residue-and-polymer-free graphene transfer: DNA-CTMA/graphene/GaN bio-hybrid photodiode for light-sensitive applications

    Science.gov (United States)

    Reddy, M. Siva Pratap; Park, Herie; Lee, Jung-Hee

    2018-02-01

    In this work, we present a residue-and-polymer-free graphene transfer method by using the adhesive force between graphene and a target substrate, the hydrophobic property of graphene, and the surface tension of the solutions. We used an n-type GaN substrate as the target substrate to make a photodiode (PD). Recently, the inclusion of biomolecules in photodetection technology has attracted considerable attention in the electronics and photonics research, particularly due to the rapid evolution of organic-inorganic bio-hybrid PDs (Bio-HPDs). This report presents a significant photoresponse of the bioinspired graphene-based PD fabricated with deoxyribonucleic acid-cetyltrimetylammonium chloride (DNA-CTMA) biomolecules on the n-type GaN substrate. Bio-HPDs respond to the infrared, visible, and ultraviolet wavelengths. Moreover, the Bio-HPDs show photosensitivities (Iphoto/Idark) of 21, 143, and 1194 for infrared, visible, and ultraviolet wavebands, respectively, which can be attributed to the integration of high-mobility graphene and photosensitive DNA-CTMA biomolecules. In addition, the corresponding charge transfer mechanisms in the PDs are explained by energy band diagrams.

  1. In Vivo Imaging of the Stability and Sustained Cargo Release of an Injectable Amphipathic Peptide-Based Hydrogel.

    Science.gov (United States)

    Oyen, Edith; Martin, Charlotte; Caveliers, Vicky; Madder, Annemieke; Van Mele, Bruno; Hoogenboom, Richard; Hernot, Sophie; Ballet, Steven

    2017-03-13

    Hydrogels are promising materials for biomedical applications such as tissue engineering and controlled drug release. In the past two decades, the peptide hydrogel subclass has attracted an increasing level of interest from the scientific community because of its numerous advantages, such as biocompatibility, biodegradability, and, most importantly, injectability. Here, we report on a hydrogel consisting of the amphipathic hexapeptide H-FEFQFK-NH 2 , which has previously shown promising in vivo properties in terms of releasing morphine. In this study, the release of a small molecule, a peptide, and a protein cargo as representatives of the three major drug classes is directly visualized by in vivo fluorescence and nuclear imaging. In addition, the in vivo stability of the peptide hydrogel system is investigated through the use of a radiolabeled hydrogelator sequence. Although it is shown that the hydrogel remains present for several days, the largest decrease in volume takes place within the first 12 h of subcutaneous injection, which is also the time frame wherein the cargos are released. Compared to the situation in which the cargos are injected in solution, a prolonged release profile is observed up to 12 h, showing the potential of our hydrogel system as a scaffold for controlled drug delivery. Importantly, this study elucidates the release mechanism of the peptide hydrogel system that seems to be based on erosion of the hydrogel providing a generally applicable controlled release platform for small molecule, peptide, and protein drugs.

  2. An Amphipathic Helix Directs Cellular Membrane Curvature Sensing and Function of the BAR Domain Protein PICK1.

    Science.gov (United States)

    Herlo, Rasmus; Lund, Viktor K; Lycas, Matthew D; Jansen, Anna M; Khelashvili, George; Andersen, Rita C; Bhatia, Vikram; Pedersen, Thomas S; Albornoz, Pedro B C; Johner, Niklaus; Ammendrup-Johnsen, Ina; Christensen, Nikolaj R; Erlendsson, Simon; Stoklund, Mikkel; Larsen, Jannik B; Weinstein, Harel; Kjærulff, Ole; Stamou, Dimitrios; Gether, Ulrik; Madsen, Kenneth L

    2018-05-15

    BAR domains are dimeric protein modules that sense, induce, and stabilize lipid membrane curvature. Here, we show that membrane curvature sensing (MCS) directs cellular localization and function of the BAR domain protein PICK1. In PICK1, and the homologous proteins ICA69 and arfaptin2, we identify an amphipathic helix N-terminal to the BAR domain that mediates MCS. Mutational disruption of the helix in PICK1 impaired MCS without affecting membrane binding per se. In insulin-producing INS-1E cells, super-resolution microscopy revealed that disruption of the helix selectively compromised PICK1 density on insulin granules of high curvature during their maturation. This was accompanied by reduced hormone storage in the INS-1E cells. In Drosophila, disruption of the helix compromised growth regulation. By demonstrating size-dependent binding on insulin granules, our finding highlights the function of MCS for BAR domain proteins in a biological context distinct from their function, e.g., at the plasma membrane during endocytosis. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

  3. The N-terminal tail of hERG contains an amphipathic α-helix that regulates channel deactivation.

    Directory of Open Access Journals (Sweden)

    Chai Ann Ng

    Full Text Available The cytoplasmic N-terminal domain of the human ether-a-go-go related gene (hERG K+ channel is critical for the slow deactivation kinetics of the channel. However, the mechanism(s by which the N-terminal domain regulates deactivation remains to be determined. Here we show that the solution NMR structure of the N-terminal 135 residues of hERG contains a previously described Per-Arnt-Sim (PAS domain (residues 26-135 as well as an amphipathic α-helix (residues 13-23 and an initial unstructured segment (residues 2-9. Deletion of residues 2-25, only the unstructured segment (residues 2-9 or replacement of the α-helix with a flexible linker all result in enhanced rates of deactivation. Thus, both the initial flexible segment and the α-helix are required but neither is sufficient to confer slow deactivation kinetics. Alanine scanning mutagenesis identified R5 and G6 in the initial flexible segment as critical for slow deactivation. Alanine mutants in the helical region had less dramatic phenotypes. We propose that the PAS domain is bound close to the central core of the channel and that the N-terminal α-helix ensures that the flexible tail is correctly orientated for interaction with the activation gating machinery to stabilize the open state of the channel.

  4. The N-terminal amphipathic helix of the topological specificity factor MinE is associated with shaping membrane curvature.

    Directory of Open Access Journals (Sweden)

    Yu-Ling Shih

    Full Text Available Pole-to-pole oscillations of the Min proteins in Escherichia coli are required for the proper placement of the division septum. Direct interaction of MinE with the cell membrane is critical for the dynamic behavior of the Min system. In vitro, this MinE-membrane interaction led to membrane deformation; however, the underlying mechanism remained unclear. Here we report that MinE-induced membrane deformation involves the formation of an amphipathic helix of MinE(2-9, which, together with the adjacent basic residues, function as membrane anchors. Biochemical evidence suggested that the membrane association induces formation of the helix, with the helical face, consisting of A2, L3, and F6, inserted into the membrane. Insertion of this helix into the cell membrane can influence local membrane curvature and lead to drastic changes in membrane topology. Accordingly, MinE showed characteristic features of protein-induced membrane tubulation and lipid clustering in in vitro reconstituted systems. In conclusion, MinE shares common protein signatures with a group of membrane trafficking proteins in eukaryotic cells. These MinE signatures appear to affect membrane curvature.

  5. Polymer films

    Science.gov (United States)

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

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

  6. A conserved degron containing an amphipathic helix regulates the cholesterol-mediated turnover of human squalene monooxygenase, a rate-limiting enzyme in cholesterol synthesis.

    Science.gov (United States)

    Chua, Ngee Kiat; Howe, Vicky; Jatana, Nidhi; Thukral, Lipi; Brown, Andrew J

    2017-12-08

    Cholesterol biosynthesis in the endoplasmic reticulum (ER) is tightly controlled by multiple mechanisms to regulate cellular cholesterol levels. Squalene monooxygenase (SM) is the second rate-limiting enzyme in cholesterol biosynthesis and is regulated both transcriptionally and post-translationally. SM undergoes cholesterol-dependent proteasomal degradation when cholesterol is in excess. The first 100 amino acids of SM (designated SM N100) are necessary for this degradative process and represent the shortest cholesterol-regulated degron identified to date. However, the fundamental intrinsic characteristics of this degron remain unknown. In this study, we performed a series of deletions, point mutations, and domain swaps to identify a 12-residue region (residues Gln-62-Leu-73), required for SM cholesterol-mediated turnover. Molecular dynamics and circular dichroism revealed an amphipathic helix within this 12-residue region. Moreover, 70% of the variation in cholesterol regulation was dependent on the hydrophobicity of this region. Of note, the earliest known Doa10 yeast degron, Deg1, also contains an amphipathic helix and exhibits 42% amino acid similarity with SM N100. Mutating SM residues Phe-35/Ser-37/Leu-65/Ile-69 into alanine, based on the key residues in Deg1, blunted SM cholesterol-mediated turnover. Taken together, our results support a model whereby the amphipathic helix in SM N100 attaches reversibly to the ER membrane depending on cholesterol levels; with excess, the helix is ejected and unravels, exposing a hydrophobic patch, which then serves as a degradation signal. Our findings shed new light on the regulation of a key cholesterol synthesis enzyme, highlighting the conservation of critical degron features from yeast to humans. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  7. Amphipathic alpha-helices and putative cholesterol binding domains of the influenza virus matrix M1 protein are crucial for virion structure organisation.

    Science.gov (United States)

    Tsfasman, Tatyana; Kost, Vladimir; Markushin, Stanislav; Lotte, Vera; Koptiaeva, Irina; Bogacheva, Elena; Baratova, Ludmila; Radyukhin, Victor

    2015-12-02

    The influenza virus matrix M1 protein is an amphitropic membrane-associated protein, forming the matrix layer immediately beneath the virus raft membrane, thereby ensuring the proper structure of the influenza virion. The objective of this study was to elucidate M1 fine structural characteristics, which determine amphitropic properties and raft membrane activities of the protein, via 3D in silico modelling with subsequent mutational analysis. Computer simulations suggest the amphipathic nature of the M1 α-helices and the existence of putative cholesterol binding (CRAC) motifs on six amphipathic α-helices. Our finding explains for the first time many features of this protein, particularly the amphitropic properties and raft/cholesterol binding potential. To verify these results, we generated mutants of the A/WSN/33 strain via reverse genetics. The M1 mutations included F32Y in the CRAC of α-helix 2, W45Y and W45F in the CRAC of α-helix 3, Y100S in the CRAC of α-helix 6, M128A and M128S in the CRAC of α-helix 8 and a double L103I/L130I mutation in both a putative cholesterol consensus motif and the nuclear localisation signal. All mutations resulted in viruses with unusual filamentous morphology. Previous experimental data regarding the morphology of M1-gene mutant influenza viruses can now be explained in structural terms and are consistent with the pivotal role of the CRAC-domains and amphipathic α-helices in M1-lipid interactions. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Nanostructures via DNA scaffold metallization

    OpenAIRE

    Ning, C.; Zinchenko, A.; Baigl, D.; Pyshkina, O.; Sergeyev, V.; Endo, Kazunaka; Yoshikawa, K.

    2005-01-01

    The critical role of polymers in process of noble metals nanostructures formation is well known, however, the use of DNA chain template in this process is yet largely unknown. In this study we demonstrate different ways of silver deposition on DNA template and report the influence of silver nanostructures formation on DNA conformational state. Metallization of DNA chain proceeds by two different scenarios depending on DNA conformation. If DNA chain is unfolded (elongated) chain, silver reduct...

  9. Biodegradable Polymers

    OpenAIRE

    Vroman, Isabelle; Tighzert, Lan

    2009-01-01

    Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources) or from biological resources (renewable resources). In general natural polymers offer fewer advantages than synthetic polymers. ...

  10. Structure-activity relationship study of Aib-containing amphipathic helical peptide-cyclic RGD conjugates as carriers for siRNA delivery.

    Science.gov (United States)

    Wada, Shun-Ichi; Takesada, Anna; Nagamura, Yurie; Sogabe, Eri; Ohki, Rieko; Hayashi, Junsuke; Urata, Hidehito

    2017-12-15

    The conjugation of Aib-containing amphipathic helical peptide with cyclo(-Arg-Gly-Asp-d-Phe-Cys-) (cRGDfC) at the C-terminus of the helix peptide (PI) has been reported to be useful for constructing a carrier for targeted siRNA delivery into cells. In order to explore structure-activity relationships for the development of potential carriers for siRNA delivery, we synthesized conjugates of Aib-containing amphipathic helical peptide with cRGDfC at the N-terminus (PII) and both the N- and C-termini (PIII) of the helical peptide. Furthermore, to examine the influence of PI helical chain length on siRNA delivery, truncated peptides containing 16 (PIV), 12 (PV), and 8 (PVI) amino acid residues at the N-terminus of the helical chain were synthesized. PII and PIII, as well as PI, could deliver anti-luciferase siRNA into cells to induce the knockdown of luciferase stably expressed in cells. In contrast, all of the truncated peptides were unlikely to transport siRNA into cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Peptides, polypeptides and peptide-polymer hybrids as nucleic acid carriers.

    Science.gov (United States)

    Ahmed, Marya

    2017-10-24

    Cell penetrating peptides (CPPs), and protein transduction domains (PTDs) of viruses and other natural proteins serve as a template for the development of efficient peptide based gene delivery vectors. PTDs are sequences of acidic or basic amphipathic amino acids, with superior membrane trespassing efficacies. Gene delivery vectors derived from these natural, cationic and cationic amphipathic peptides, however, offer little flexibility in tailoring the physicochemical properties of single chain peptide based systems. Owing to significant advances in the field of peptide chemistry, synthetic mimics of natural peptides are often prepared and have been evaluated for their gene expression, as a function of amino acid functionalities, architecture and net cationic content of peptide chains. Moreover, chimeric single polypeptide chains are prepared by a combination of multiple small natural or synthetic peptides, which imparts distinct physiological properties to peptide based gene delivery therapeutics. In order to obtain multivalency and improve the gene delivery efficacies of low molecular weight cationic peptides, bioactive peptides are often incorporated into a polymeric architecture to obtain novel 'polymer-peptide hybrids' with improved gene delivery efficacies. Peptide modified polymers prepared by physical or chemical modifications exhibit enhanced endosomal escape, stimuli responsive degradation and targeting efficacies, as a function of physicochemical and biological activities of peptides attached onto a polymeric scaffold. The focus of this review is to provide comprehensive and step-wise progress in major natural and synthetic peptides, chimeric polypeptides, and peptide-polymer hybrids for nucleic acid delivery applications.

  12. Controlled Release from Recombinant Polymers

    Science.gov (United States)

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-01-01

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

  13. Polymer compound

    NARCIS (Netherlands)

    1995-01-01

    A Polymer compound comprising a polymer (a) that contains cyclic imidesgroups and a polymer (b) that contains monomer groups with a 2,4-diamino-1,3,5-triazine side group. According to the formula (see formula) whereby themole percentage ratio of the cyclic imides groups in the polymer compoundwith

  14. Polymer electronics

    CERN Document Server

    Hsin-Fei, Meng

    2013-01-01

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

  15. Septal membrane localization by C-terminal amphipathic α-helices of MinD in Bacillus subtilis mutant cells lacking MinJ or DivIVA.

    Science.gov (United States)

    Ishikawa, Kazuki; Matsuoka, Satoshi; Hara, Hiroshi; Matsumoto, Kouji

    2017-10-18

    The Min system, which inhibits assembly of the cytokinetic protein FtsZ, is largely responsible for positioning the division site in rod-shaped bacteria. It has been reported that MinJ, which bridges DivIVA and MinD, is targeted to the cell poles by an interaction with DivIVA, and that MinJ in turn recruits MinCD to the cell poles. MinC, however, is located primarily at active division sites at mid-cell when expressed from its native promoter. Surprisingly, we found that Bacillus subtilis MinD is located at nascent septal membranes and at an asymmetric site on lateral membranes between nascent septal membranes in filamentous cells lacking MinJ or DivIVA. Bacillus subtilis MinD has two amphipathic α-helices rich in basic amino acid residues at its C-terminus; one of these, named MTS1 here, is the counterpart of the membrane targeting sequence (MTS) in Escherichia coli MinD while the other, named MTS-like sequence (MTSL), is the nearest helix to MTS1. These amphipathic helices were located independently at nascent septal membranes in cells lacking MinJ or DivIVA, whereas elimination of the helices from the wild type protein reduced its localization considerably. MinD variants with altered MTS1 and MTSL, in which basic amino acid residues were replaced with proline or acidic residues, were not located at nascent septal membranes, indicating that the binding to the nascent septal membranes requires basic residues and a helical structure. The septal localization of MTSL, but not of MTS1, was dependent on host cell MinD. These results suggest that MinD is targeted to nascent septal membranes via its C-terminal amphipathic α-helices in B. subtilis cells lacking MinJ or DivIVA. Moreover, the diffuse distribution of MinD lacking both MTSs suggests that only a small fraction of MinD depends on MinJ for its localization to nascent septal membranes.

  16. DNA nanotechnology: On-command molecular Trojans

    Science.gov (United States)

    Niemeyer, Christof M.

    2017-12-01

    Lipid-motif-decorated DNA nanocapsules filled with photoresponsive polymers are capable of delivering signalling molecules into target organisms for biological perturbations at high spatiotemporal resolution.

  17. Fluorescence Microscopy of Nanochannel-Confined DNA.

    Science.gov (United States)

    Westerlund, Fredrik; Persson, Fredrik; Fritzsche, Joachim; Beech, Jason P; Tegenfeldt, Jonas O

    2018-01-01

    Stretching of DNA in nanoscale confinement allows for several important studies. The genetic contents of the DNA can be visualized on the single DNA molecule level and both the polymer physics of confined DNA and also DNA/protein and other DNA/DNA-binding molecule interactions can be explored. This chapter describes the basic steps to fabricate the nanostructures, perform the experiments and analyze the data.

  18. PHOTOREFRACTIVE POLYMERS

    NARCIS (Netherlands)

    Morichere, D; Malliaras, G.G; Krasnikov, V.V.; Bolink, H.J; Hadziioannou, G

    The use of polymers as photorefractive materials offers many advantages : flexibility in synthesis, doping, processing and low cost. The required functionalities responsible for photorefractivity, namely charge generation, transport, trapping and linear electrooptic effect are given in the polymer

  19. Photorefractive polymers

    NARCIS (Netherlands)

    Bolink, Hendrik Jan; Hadziioannou, G

    1997-01-01

    This thesis describes the synthesis and properties of photorefractive polymers. Photorefractive polymers are materials in which the refractive index can be varied by the interaction with light. Unlike in numerous other photosensitive materials, in photorefractive materials this occurs via

  20. Polymer Brushes

    NARCIS (Netherlands)

    Vos, de W.M.; Kleijn, J.M.; Keizer, de A.; Cosgrove, T.; Cohen Stuart, M.A.

    2010-01-01

    A polymer brush can be defined as a dense array of polymers end-attached to an interface that stretch out into the surrounding medium. Polymer brushes have been investigated for the past 30 years and have shown to be an extremely useful tool to control interfacial properties. This review is intended

  1. Polymer crowding and shape distributions in polymer-nanoparticle mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Wei Kang; Denton, Alan R., E-mail: alan.denton@ndsu.edu [Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050 (United States)

    2014-09-21

    Macromolecular crowding can influence polymer shapes, which is important for understanding the thermodynamic stability of polymer solutions and the structure and function of biopolymers (proteins, RNA, DNA) under confinement. We explore the influence of nanoparticle crowding on polymer shapes via Monte Carlo simulations and free-volume theory of a coarse-grained model of polymer-nanoparticle mixtures. Exploiting the geometry of random walks, we model polymer coils as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor. Accounting for the entropic cost of a nanoparticle penetrating a larger polymer coil, we compute the crowding-induced shift in the shape distributions, radius of gyration, and asphericity of ideal polymers in a theta solvent. With increased nanoparticle crowding, we find that polymers become more compact (smaller, more spherical), in agreement with predictions of free-volume theory. Our approach can be easily extended to nonideal polymers in good solvents and used to model conformations of biopolymers in crowded environments.

  2. Polymer crowding and shape distributions in polymer-nanoparticle mixtures

    International Nuclear Information System (INIS)

    Lim, Wei Kang; Denton, Alan R.

    2014-01-01

    Macromolecular crowding can influence polymer shapes, which is important for understanding the thermodynamic stability of polymer solutions and the structure and function of biopolymers (proteins, RNA, DNA) under confinement. We explore the influence of nanoparticle crowding on polymer shapes via Monte Carlo simulations and free-volume theory of a coarse-grained model of polymer-nanoparticle mixtures. Exploiting the geometry of random walks, we model polymer coils as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor. Accounting for the entropic cost of a nanoparticle penetrating a larger polymer coil, we compute the crowding-induced shift in the shape distributions, radius of gyration, and asphericity of ideal polymers in a theta solvent. With increased nanoparticle crowding, we find that polymers become more compact (smaller, more spherical), in agreement with predictions of free-volume theory. Our approach can be easily extended to nonideal polymers in good solvents and used to model conformations of biopolymers in crowded environments

  3. Elasticity of semiflexible polymers in two dimensions

    Science.gov (United States)

    Prasad, Ashok; Hori, Yuko; Kondev, Jané

    2005-10-01

    We study theoretically the entropic elasticity of a semiflexible polymer, such as DNA, confined to two dimensions. Using the worm-like-chain model we obtain an exact analytical expression for the partition function of the polymer pulled at one end with a constant force. The force-extension relation for the polymer is computed in the long chain limit in terms of Mathieu characteristic functions. We also present applications to the interaction between a semiflexible polymer and a nematic field, and derive the nematic order parameter and average extension of the polymer in a strong field.

  4. Polymer Directed Protein Assemblies

    Directory of Open Access Journals (Sweden)

    Patrick van Rijn

    2013-05-01

    Full Text Available Protein aggregation and protein self-assembly is an important occurrence in natural systems, and is in some form or other dictated by biopolymers. Very obvious influences of biopolymers on protein assemblies are, e.g., virus particles. Viruses are a multi-protein assembly of which the morphology is dictated by poly-nucleotides namely RNA or DNA. This “biopolymer” directs the proteins and imposes limitations on the structure like the length or diameter of the particle. Not only do these bionanoparticles use polymer-directed self-assembly, also processes like amyloid formation are in a way a result of directed protein assembly by partial unfolded/misfolded biopolymers namely, polypeptides. The combination of proteins and synthetic polymers, inspired by the natural processes, are therefore regarded as a highly promising area of research. Directed protein assembly is versatile with respect to the possible interactions which brings together the protein and polymer, e.g., electrostatic, v.d. Waals forces or covalent conjugation, and possible combinations are numerous due to the large amounts of different polymers and proteins available. The protein-polymer interacting behavior and overall morphology is envisioned to aid in clarifying protein-protein interactions and are thought to entail some interesting new functions and properties which will ultimately lead to novel bio-hybrid materials.

  5. Routing of individual polymers in designed patterns

    DEFF Research Database (Denmark)

    Knudsen, Jakob Bach; Liu, Lei; Kodal, Anne Louise Bank

    2015-01-01

    Synthetic polymers are ubiquitous in the modern world, but our ability to exert control over the molecular conformation of individual polymers is very limited. In particular, although the programmable self-assembly of oligonucleotides and proteins into artificial nanostructures has been...... demonstrated, we currently lack the tools to handle other types of synthetic polymers individually and thus the ability to utilize and study their single-molecule properties. Here we show that synthetic polymer wires containing short oligonucleotides that extend from each repeat can be made to assemble...... into arbitrary routings. The wires, which can be more than 200 nm in length, are soft and bendable, and the DNA strands allow individual polymers to self-assemble into predesigned routings on both two- and three-dimensional DNA origami templates. The polymers are conjugated and potentially conducting, and could...

  6. Routing of individual polymers in designed patterns

    Science.gov (United States)

    Knudsen, Jakob Bach; Liu, Lei; Bank Kodal, Anne Louise; Madsen, Mikael; Li, Qiang; Song, Jie; Woehrstein, Johannes B.; Wickham, Shelley F. J.; Strauss, Maximilian T.; Schueder, Florian; Vinther, Jesper; Krissanaprasit, Abhichart; Gudnason, Daniel; Smith, Anton Allen Abbotsford; Ogaki, Ryosuke; Zelikin, Alexander N.; Besenbacher, Flemming; Birkedal, Victoria; Yin, Peng; Shih, William M.; Jungmann, Ralf; Dong, Mingdong; Gothelf, Kurt V.

    2015-10-01

    Synthetic polymers are ubiquitous in the modern world, but our ability to exert control over the molecular conformation of individual polymers is very limited. In particular, although the programmable self-assembly of oligonucleotides and proteins into artificial nanostructures has been demonstrated, we currently lack the tools to handle other types of synthetic polymers individually and thus the ability to utilize and study their single-molecule properties. Here we show that synthetic polymer wires containing short oligonucleotides that extend from each repeat can be made to assemble into arbitrary routings. The wires, which can be more than 200 nm in length, are soft and bendable, and the DNA strands allow individual polymers to self-assemble into predesigned routings on both two- and three-dimensional DNA origami templates. The polymers are conjugated and potentially conducting, and could therefore be used to create molecular-scale electronic or optical wires in arbitrary geometries.

  7. Polymer Crowding in Confined Polymer-Nanoparticle Mixtures

    Science.gov (United States)

    Davis, Wyatt J.; Denton, Alan R.

    Crowding can influence the conformations and thus functionality of macromolecules in quasi-two-dimensional environments, such as DNA or proteins confined to a cell membrane. We explore such crowding within a model of polymers as penetrable ellipses, whose shapes are governed by the statistics of a 2D random walk. The principal radii of the polymers fluctuate according to probability distributions of the eigenvalues of the gyration tensor. Within this coarse-grained model, we perform Monte Carlo simulations of mixtures of polymers and hard nanodisks, including trial changes in polymer conformation (shape and orientation). Penetration of polymers by nanodisks is incorporated with a free energy cost predicted by polymer field theory. Over ranges of size ratio and nanodisk density, we analyze the influence of crowding on polymer shape by computing eigenvalue distributions, mean radius of gyration, and mean asphericity of the polymer. We compare results with predictions of free-volume theory and with corresponding results in three dimensions. Our approach may help to interpret recent (and motivate future) experimental studies of biopolymers interacting with cell membranes, with relevance for drug delivery and gene therapy. This work was supported by the National Science Foundation under Grant No. DMR-1106331.

  8. Nonlinear optical and G-Quadruplex DNA stabilization properties of novel mixed ligand copper(II) complexes and coordination polymers: Synthesis, structural characterization and computational studies

    Science.gov (United States)

    Rajasekhar, Bathula; Bodavarapu, Navya; Sridevi, M.; Thamizhselvi, G.; RizhaNazar, K.; Padmanaban, R.; Swu, Toka

    2018-03-01

    The present study reports the synthesis and evaluation of nonlinear optical property and G-Quadruplex DNA Stabilization of five novel copper(II) mixed ligand complexes. They were synthesized from copper(II) salt, 2,5- and 2,3- pyridinedicarboxylic acid, diethylenetriamine and amide based ligand (AL). The crystal structure of these complexes were determined through X-ray diffraction and supported by ESI-MAS, NMR, UV-Vis and FT-IR spectroscopic methods. Their nonlinear optical property was studied using Gaussian09 computer program. For structural optimization and nonlinear optical property, density functional theory (DFT) based B3LYP method was used with LANL2DZ basis set for metal ion and 6-31G∗ for C,H,N,O and Cl atoms. The present work reveals that pre-polarized Complex-2 showed higher β value (29.59 × 10-30e.s.u) as compared to that of neutral complex-1 (β = 0.276 × 10-30e.s.u.) which may be due to greater advantage of polarizability. Complex-2 is expected to be a potential material for optoelectronic and photonic technologies. Docking studies using AutodockVina revealed that complex-2 has higher binding energy for both G-Quadruplex DNA (-8.7 kcal/mol) and duplex DNA (-10.1 kcal/mol). It was also observed that structure plays an important role in binding efficiency.

  9. Polymer Electrolytes

    Science.gov (United States)

    Hallinan, Daniel T.; Balsara, Nitash P.

    2013-07-01

    This review article covers applications in which polymer electrolytes are used: lithium batteries, fuel cells, and water desalination. The ideas of electrochemical potential, salt activity, and ion transport are presented in the context of these applications. Potential is defined, and we show how a cell potential measurement can be used to ascertain salt activity. The transport parameters needed to fully specify a binary electrolyte (salt + solvent) are presented. We define five fundamentally different types of homogeneous electrolytes: type I (classical liquid electrolytes), type II (gel electrolytes), type III (dry polymer electrolytes), type IV (dry single-ion-conducting polymer electrolytes), and type V (solvated single-ion-conducting polymer electrolytes). Typical values of transport parameters are provided for all types of electrolytes. Comparison among the values provides insight into the transport mechanisms occurring in polymer electrolytes. It is desirable to decouple the mechanical properties of polymer electrolyte membranes from the ionic conductivity. One way to accomplish this is through the development of microphase-separated polymers, wherein one of the microphases conducts ions while the other enhances the mechanical rigidity of the heterogeneous polymer electrolyte. We cover all three types of conducting polymer electrolyte phases (types III, IV, and V). We present a simple framework that relates the transport parameters of heterogeneous electrolytes to homogeneous analogs. We conclude by discussing electrochemical stability of electrolytes and the effects of water contamination because of their relevance to applications such as lithium ion batteries.

  10. Star Polymers.

    Science.gov (United States)

    Ren, Jing M; McKenzie, Thomas G; Fu, Qiang; Wong, Edgar H H; Xu, Jiangtao; An, Zesheng; Shanmugam, Sivaprakash; Davis, Thomas P; Boyer, Cyrille; Qiao, Greg G

    2016-06-22

    Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

  11. Polymer chemistry (revised edition)

    International Nuclear Information System (INIS)

    Kim, Jae Mum

    1987-02-01

    This book deals with polymer chemistry, which is divided into fourteen chapters. The contents of this book are development of polymer chemistry, conception of polymer, measurement of polymer chemistry, conception of polymer, measurement of polymer, molecule structure of polymer, thermal prosperities of solid polymer, basic theory of polymerization, radical polymerization, ion polymerization, radical polymerization, copolymerization, polymerization by step-reaction, polymer reaction, crown polymer and inorganic polymer on classification and process of creation such as polymeric sulfur and carbon fiber.

  12. Loss of bottlebrush stiffness due to free polymers

    NARCIS (Netherlands)

    Storm, I.M.; Kornreich, M.; Voets, I.K.; Beck, R.; de Vries, R.; Cohen Stuart, M.A.; Leermakers, F.A.M.

    2016-01-01

    A recently introduced DNA-bottlebrush system, which is formed by the co-assembly of DNA with a genetically engineered cationic polymer-like protein, is subjected to osmotic stress conditions. We measured the inter-DNA distances by X-ray scattering. Our co-assembled DNA-bottlebrush system is one of

  13. A FRET-based probe for epidermal growth factor receptor bound non-covalently to a pair of synthetic amphipathic helixes

    International Nuclear Information System (INIS)

    Itoh, Reina E.; Kurokawa, Kazuo; Fujioka, Aki; Sharma, Alok; Mayer, Bruce J.; Matsuda, Michiyuki

    2005-01-01

    Epidermal growth factor (EGF) receptor plays a pivotal role in a variety of cellular functions, such as proliferation, differentiation, and migration. To monitor the EGF receptor (EGFR) activity in living cells, we developed a probe for EGFR activity based on the principle of fluorescence resonance energy transfer (FRET). Previously, we developed a probe designated as Picchu (Phosphorylation indicator of the CrkII chimeric unit), which detects the tyrosine phosphorylation of the CrkII adaptor protein. We used a pair of synthetic amphipathic helixes, WinZipA2 and WinZipB1, to bind Picchu non-covalently to the carboxyl-terminus of the EGFR. Using this modified probe named Picchu-Z, the activity of EGFR was followed in EGF-stimulated Cos7 cells. We found that a high level of tyrosine phosphorylation of Picchu-Z probe remained after endocytosis until the point when the EGFR was translocated to the perinuclear region. These findings are in agreement with the previously reported 'signaling endosome' model. Furthermore, by pulse stimulation with EGF and by acute ablation of EGFR activity with AG1478, it was suggested that the phosphorylation of Picchu-Z probe, and probably the phosphorylation of EGFR also, underwent a rapid equilibrium (τ 1/2 < 2 min) between the phosphorylated and dephosphorylated states in the presence of EGF

  14. Polymer fragmentation in extensional flow

    Energy Technology Data Exchange (ETDEWEB)

    Maroja, Armando M.; Oliveira, Fernando A.; Ciesla, Michal; Longa, Lech

    2001-06-01

    In this paper we present an analysis of fragmentation of dilute polymer solutions in extensional flow. The transition rate is investigated both from theoretical and computational approaches, where the existence of a Gaussian distribution for the breaking bonds has been controversial. We give as well an explanation for the low fragmentation frequency found in DNA experiments.

  15. Duox2-induced innate immune responses in the respiratory epithelium and intranasal delivery of Duox2 DNA using polymer that mediates immunization.

    Science.gov (United States)

    Jeon, Yung Jin; Kim, Hyun Jik

    2018-05-01

    Respiratory mucosa especially nasal epithelium is well known as the first-line barrier of air-borne pathogens. High levels of reactive oxygen species (ROS) are detected in in vitro cultured human epithelial cells and in vivo lung. With identification of NADPH oxidase (Nox) system of respiratory epithelium, the antimicrobial role of ROS has been studied. Duox2 is the most abundant Nox isoform and produces the regulated amount of ROS in respiratory epithelium. Duox2-derived ROS are involved in antiviral innate immune responses but more studies are needed to verify the mechanism. In respiratory epithelium, Duox2-derived ROS is critical for recognition of virus through families retinoic acid-inducible gene-I (RIG-I) and melanoma differentiation-associated protein 5 (MDA5) at the early stage of antiviral innate immune responses. Various secreted interferons (IFNs) play essential roles for antiviral host defense by downstream cell signaling, and transcription of IFN-stimulated genes is started to suppress viral replication. Type I and type III IFNs are verified more responsible for influenza A virus (IAV) infection in respiratory epithelium and Duox2 is required to regulate IFN-related immune responses. Transient overexpression of Duox2 using cationic polymer polyethylenimine (PEI) induces secretion of type I and type III IFNs and significantly attenuated IAV replication in respiratory epithelium. Here, we discuss Duox2-mediated antiviral innate immune responses and the role of Duox2 as a mucosal vaccine to resist respiratory viral infection.

  16. Ancient DNA

    DEFF Research Database (Denmark)

    Willerslev, Eske; Cooper, Alan

    2004-01-01

    ancient DNA, palaeontology, palaeoecology, archaeology, population genetics, DNA damage and repair......ancient DNA, palaeontology, palaeoecology, archaeology, population genetics, DNA damage and repair...

  17. Polymer Nanocomposites

    Indian Academy of Sciences (India)

    methods for the synthesis of polymer nanocomposites. In this article we .... ers, raw materials recovery, drug delivery and anticorrosion .... region giving rise to dose-packed absorption bands called an IR ... using quaternary ammonium salts.

  18. Complex formation and vectorization of a phosphorothioate oligonucleotide with an amphipathic leucine- and lysine-rich peptide: study at molecular and cellular levels.

    Science.gov (United States)

    Boukhalfa-Heniche, Fatima-Zohra; Hernández, Belén; Gaillard, Stéphane; Coïc, Yves-Marie; Huynh-Dinh, Tam; Lecouvey, Marc; Seksek, Olivier; Ghomi, Mahmoud

    2004-04-15

    Optical spectroscopic techniques such as CD, Raman scattering, and fluorescence imaging allowed us to analyze the complex formation and vectorization of a single-stranded 20-mer phosphorothioate oligodeoxynucleotide with a 15-mer amphipathic peptide at molecular and cellular levels. Different solvent mixtures (methanol and water) and molecular ratios of peptide/oligodeoxynucleotide complexes were tested in order to overcome the problems related to solubility. Optimal conditions for both spectroscopic and cellular experiments were obtained with the molecular ratio peptide/oligodeoxynucleotide equal to 21:4, corresponding to a 7:5 ratio for their respective +/- charge ratio. At the molecular level, CD and Raman spectra were consistent with a alpha-helix conformation of the peptide in water or in a methanol-water mixture. The presence of methanol increased considerably the solubility of the peptide without altering its alpha-helix conformation, as evidenced by CD and Raman spectroscopies. UV absorption melting profile of the oligodeoxynucleotide gave rise to a flat melting profile, corresponding to its random structure in solution. Raman spectra of oligodeoxynucleotide/peptide complexes could only be studied in methanol/water mixture solutions. Drastic changes observed in Raman spectra have undoubtedly shown: (a) the perturbation occurred in the peptide secondary structure, and (b) possible interaction between the lysine residues of the peptide and the oligodeoxynucleotide. At the cellular level, the complex was prepared in a mixture of 10% methanol and 90% cell medium. Cellular uptake in optimal conditions for the oligodeoxynucleotide delivery with low cytotoxicity was controlled by fluorescence imaging allowing to specifically locate the compacted oligonucleotide labeled with fluorescein at its 5'-terminus with the peptide into human glioma cells after 1 h of incubation at 37 degrees C. Copyright 2004 Wiley Periodicals, Inc.

  19. An amphipathic alpha-helix controls multiple roles of brome mosaic virus protein 1a in RNA replication complex assembly and function.

    Directory of Open Access Journals (Sweden)

    Ling Liu

    2009-03-01

    Full Text Available Brome mosaic virus (BMV protein 1a has multiple key roles in viral RNA replication. 1a localizes to perinuclear endoplasmic reticulum (ER membranes as a peripheral membrane protein, induces ER membrane invaginations in which RNA replication complexes form, and recruits and stabilizes BMV 2a polymerase (2a(Pol and RNA replication templates at these sites to establish active replication complexes. During replication, 1a provides RNA capping, NTPase and possibly RNA helicase functions. Here we identify in BMV 1a an amphipathic alpha-helix, helix A, and use NMR analysis to define its structure and propensity to insert in hydrophobic membrane-mimicking micelles. We show that helix A is essential for efficient 1a-ER membrane association and normal perinuclear ER localization, and that deletion or mutation of helix A abolishes RNA replication. Strikingly, mutations in helix A give rise to two dramatically opposite 1a function phenotypes, implying that helix A acts as a molecular switch regulating the intricate balance between separable 1a functions. One class of helix A deletions and amino acid substitutions markedly inhibits 1a-membrane association and abolishes ER membrane invagination, viral RNA template recruitment, and replication, but doubles the 1a-mediated increase in 2a(Pol accumulation. The second class of helix A mutations not only maintains efficient 1a-membrane association but also amplifies the number of 1a-induced membrane invaginations 5- to 8-fold and enhances viral RNA template recruitment, while failing to stimulate 2a(Pol accumulation. The results provide new insights into the pathways of RNA replication complex assembly and show that helix A is critical for assembly and function of the viral RNA replication complex, including its central role in targeting replication components and controlling modes of 1a action.

  20. Regulator of differentiation 1 (ROD1) binds to the amphipathic C-terminal peptide of thrombospondin-4 and is involved in its mitogenic activity.

    Science.gov (United States)

    Sadvakassova, Gulzhakhan; Dobocan, Monica C; Difalco, Marcos R; Congote, Luis F

    2009-09-01

    The matrix protein thrombospondin-4 has an acidic amphipathic C-terminal peptide (C21) which stimulates erythroid cell proliferation. Here we show that C21 stimulates red cell formation in anemic mice in vivo. In vitro experiments indicated that the peptide-mediated increase of erythroid colony formation in cultures of human CD34+ hematopoietic progenitor cells was possible only under continuous presence of erythropoietin. In the absence of this cytokine, C21 stimulated exclusively myeloid colony formation. Therefore, the peptide is not a specific erythroid differentiation factor. In fact, it is mitogenic in non-erythroid cells, such as skin fibroblasts and kidney epithelial cells. In erythroleukemic TF-1 cells, it actually decreased the production of the erythroid differentiation marker glycophorin A. C21-affinity chromatography revealed regulator of differentiation 1 (ROD1) as a major C21-binding protein. ROD1 is the hematopoietic cell paralog of polypyrimidine tract binding proteins (PTBs), RNA splice regulators which regulate differentiation by repressing tissue-specific exons. ROD1 binding to C21 was strongly inhibited by synthetic RNAs in the order poly A > poly U > poly G = poly C and was weakly inhibited by a synthetic phosphorylated peptide mimicking the C-terminal domain of RNA polymerase II. Cellular overexpression or knockdown experiments of ROD1 suggest a role for this protein in the mitogenic activity of C21. Since the nuclear proteins ROD1 and PTBs regulate differentiation at a posttranscriptional level and there is a fast nuclear uptake of C21, we put forward the idea that the peptide is internalized, goes to the nucleus and maintains cells in a proliferative state by supporting ROD1-mediated inhibition of differentiation.

  1. Příprava DNA v kvalitě vhodné pro polymerázovou řetězovou reakci

    OpenAIRE

    Čuta, Robert

    2011-01-01

    Bakterie mléčného kvašení (BMK) jsou ve velké míře využívány v potravinářském průmyslu například při výrobě mléčných výrobků, sýrů a fermentovaných salámů, dále se využívají ke konzervaci zeleniny. Kromě průmyslového využití jsou u BMK důležité i mikrobiologické parametry. Při identifikaci bakteriálních rodů se v poslední době velmi často využívají metody založené na izolaci a amplifikaci DNA. Diplomová práce se zabývá optimalizací lyze bakteriálních buněk rodu Lactobacillus. Jako první byla ...

  2. Polymer nanocomposites: polymer and particle dynamics

    KAUST Repository

    Kim, Daniel; Srivastava, Samanvaya; Narayanan, Suresh; Archer, Lynden A.

    2012-01-01

    Polymer nanocomposites containing nanoparticles smaller than the random coil size of their host polymer chains are known to exhibit unique properties, such as lower viscosity and glass transition temperature relative to the neat polymer melt. It has

  3. Antimocrobial Polymer

    Science.gov (United States)

    McDonald, William F.; Huang, Zhi-Heng; Wright, Stacy C.

    2005-09-06

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from quaternary ammonium compounds, gentian violet compounds, substituted or unsubstituted phenols, biguanide compounds, iodine compounds, and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A)3P wherein A is hydroxyalkyl; and the antimicrobial agent is chlorhexidine, dimethylchlorophenol, cetyl pyridinium chloride, gentian violet, triclosan, thymol, iodine, and mixtures thereof.

  4. Polymer electronics

    CERN Document Server

    Geoghegan, Mark

    2013-01-01

    Polymer electronics is the science behind many important new developments in technology, such as the flexible electronic display (e-ink) and many new developments in transistor technology. Solar cells, light-emitting diodes, and transistors are all areas where plastic electronics is likely to, or is already having, a serious impact on our daily lives. With polymer transistors and light-emitting diodes now being commercialised, there is a clear need for a pedagogic text thatdiscusses the subject in a clear and concise fashion suitable for senior undergraduate and graduate students. The content

  5. TH17 cells promote microbial killing and innate immune sensing of DNA via interleukin 26

    KAUST Repository

    Meller, Stephan; Di Domizio, Jeremy; Voo, Kui S; Friedrich, Heike C; Chamilos, Georgios; Ganguly, Dipyaman; Conrad, Curdin; Gregorio, Josh; Le Roy, Didier; Roger, Thierry; Ladbury, John E; Homey, Bernhard; Watowich, Stanley; Modlin, Robert L; Kontoyiannis, Dimitrios P; Liu, Yong-Jun; Arold, Stefan T.; Gilliet, Michel

    2015-01-01

    Interleukin 17-producing helper T cells (TH 17 cells) have a major role in protection against infections and in mediating autoimmune diseases, yet the mechanisms involved are incompletely understood. We found that interleukin 26 (IL-26), a human TH17 cell-derived cytokine, is a cationic amphipathic protein that kills extracellular bacteria via membrane-pore formation. Furthermore, TH17 cell-derived IL-26 formed complexes with bacterial DNA and self-DNA released by dying bacteria and host cells. The resulting IL-26-DNA complexes triggered the production of type I interferon by plasmacytoid dendritic cells via activation of Toll-like receptor 9, but independently of the IL-26 receptor. These findings provide insights into the potent antimicrobial and proinflammatory function of TH17 cells by showing that IL-26 is a natural human antimicrobial that promotes immune sensing of bacterial and host cell death. © 2015 Nature America, Inc.

  6. TH17 cells promote microbial killing and innate immune sensing of DNA via interleukin 26

    KAUST Repository

    Meller, Stephan

    2015-07-13

    Interleukin 17-producing helper T cells (TH 17 cells) have a major role in protection against infections and in mediating autoimmune diseases, yet the mechanisms involved are incompletely understood. We found that interleukin 26 (IL-26), a human TH17 cell-derived cytokine, is a cationic amphipathic protein that kills extracellular bacteria via membrane-pore formation. Furthermore, TH17 cell-derived IL-26 formed complexes with bacterial DNA and self-DNA released by dying bacteria and host cells. The resulting IL-26-DNA complexes triggered the production of type I interferon by plasmacytoid dendritic cells via activation of Toll-like receptor 9, but independently of the IL-26 receptor. These findings provide insights into the potent antimicrobial and proinflammatory function of TH17 cells by showing that IL-26 is a natural human antimicrobial that promotes immune sensing of bacterial and host cell death. © 2015 Nature America, Inc.

  7. Polymer physics

    CERN Document Server

    Gedde, Ulf W

    1999-01-01

    This book is the result of my teaching efforts during the last ten years at the Royal Institute of Technology. The purpose is to present the subject of polymer physics for undergraduate and graduate students, to focus the fundamental aspects of the subject and to show the link between experiments and theory. The intention is not to present a compilation of the currently available literature on the subject. Very few reference citations have thus been made. Each chapter has essentially the same structure: starling with an introduction, continuing with the actual subject, summarizing the chapter in 30D-500 words, and finally presenting problems and a list of relevant references for the reader. The solutions to the problems presented in Chapters 1-12 are given in Chapter 13. The theme of the book is essentially polymer science, with the exclusion of that part dealing directly with chemical reactions. The fundamentals in polymer science, including some basic polymer chemistry, are presented as an introduction in t...

  8. Antimicrobial polymers.

    Science.gov (United States)

    Jain, Anjali; Duvvuri, L Sailaja; Farah, Shady; Beyth, Nurit; Domb, Abraham J; Khan, Wahid

    2014-12-01

    Better health is basic requirement of human being, but the rapid growth of harmful pathogens and their serious health effects pose a significant challenge to modern science. Infections by pathogenic microorganisms are of great concern in many fields such as medical devices, drugs, hospital surfaces/furniture, dental restoration, surgery equipment, health care products, and hygienic applications (e.g., water purification systems, textiles, food packaging and storage, major or domestic appliances etc.) Antimicrobial polymers are the materials having the capability to kill/inhibit the growth of microbes on their surface or surrounding environment. Recently, they gained considerable interest for both academic research and industry and were found to be better than their small molecular counterparts in terms of enhanced efficacy, reduced toxicity, minimized environmental problems, resistance, and prolonged lifetime. Hence, efforts have focused on the development of antimicrobial polymers with all desired characters for optimum activity. In this Review, an overview of different antimicrobial polymers, their mechanism of action, factors affecting antimicrobial activity, and application in various fields are given. Recent advances and the current clinical status of these polymers are also discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Polymer blends

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Scott D.; Naik, Sanjeev

    2017-08-22

    The present invention provides, among other things, extruded blends of aliphatic polycarbonates and polyolefins. In one aspect, provided blends comprise aliphatic polycarbonates such as poly(propylene carbonate) and a lesser amount of a crystalline or semicrystalline polymer. In certain embodiments, provided blends are characterized in that they exhibit unexpected improvements in their elongation properties. In another aspect, the invention provides methods of making such materials and applications of the materials in applications such as the manufacture of consumer packaging materials.

  10. Integrated Sensing Using DNA Nanoarchitectures

    Science.gov (United States)

    2014-05-20

    Norton. Thiolated Dendrimers as Multi-Point Binding Headgroups for DNA Immobilization on Gold, Langmuir, (10 2011): 0. doi: 10.1021/la202444s...flat mica surface, the structure is planar (it is conformal, lacking rigidity as a 2 nm thick polymer sheet. The simulated structure is shown in...Morris, John R., and Norton, Michael L.; Thiolated Dendrimers as Multi-Point Binding Headgroups for DNA Immobilization on Gold, Langmuir, 27(20

  11. Polymer physics of nuclear organization and function

    Energy Technology Data Exchange (ETDEWEB)

    Amitai, A. [Department of Chemical Engineering, Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Holcman, D., E-mail: david.holcman@ens.fr [Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge, Churchill College, CB30DS, Cambridge (United Kingdom); Ecole Normale Superieure, Paris (France)

    2017-03-23

    We review here recent progress to link the nuclear organization to its function, based on elementary physical processes such as diffusion, polymer dynamics of DNA, chromatin and the search mechanism for a small target by double-stranded DNA (dsDNA) break. These physical models and their analysis make it possible to compute critical rates involved in cell reorganization timing, which depend on many parameters. In the framework of polymer models, various empirical observations are interpreted as anomalous diffusion of chromatin at various time scales. The reviewed theoretical approaches offer a framework for extracting features, biophysical parameters, predictions, and so on, based on a large variety of experimental data, such as chromosomal capture data, single particle trajectories, and more. Combining theoretical approaches with live cell microscopy data should unveil some of the still unexplained behavior of the nucleus in carrying out some of its key function involved in survival, DNA repair or gene activation.

  12. Natural polymers: an overview

    CSIR Research Space (South Africa)

    John, MJ

    2012-08-01

    Full Text Available The scarcity of natural polymers during the world war years led to the development of synthetic polymers like nylon, acrylic, neoprene, styrene-butadiene rubber (SBR) and polyethylene. The increasing popularity of synthetic polymers is partly due...

  13. Polymer dynamics from synthetic polymers to proteins

    Indian Academy of Sciences (India)

    Keywords. Polymer dynamics; reptation; domain dynamics biomolecules. Abstract. Starting from the standard model of polymer motion - the Rouse model - we briefly present some key experimental results on the mesoscopic dynamics of polymer systems. We touch the role of topological confinement as expressed in the ...

  14. UVB DNA dosimeters analyzed by polymerase chain reactors

    International Nuclear Information System (INIS)

    Yoshida, Hiroko; Regan, J.D.; Florida Inst. of Tech., Melbourne, FL

    1997-01-01

    Purified bacteriophage λ DNA was dried on a UV-transparent polymer film and served as a UVB dosimeter for personal and ecological applications. Bacteriophage λ DNA was chosen because it is commercially available and inexpensive, and its entire sequence is known. Each dosimeter contained two sets of DNA sandwiched between UV-transparent polymer films, one exposed to solar radiation (experimental) and another protected from UV radiation by black paper (control). The DNA dosimeter was then analyzed by a polymerase chain reaction (PCR) that amplifies a 500 base pair specific region of λ DNA. Photoinduced damage in DNA blocks polymerase from synthesizing a new strand; therefore, the amount of amplified product in UV-exposed DNA was reduced from that found in control DNA. The dried λ DNA dosimeter is compact, robust, safe and transportable, stable over long storage times and provides the total UVB dose integrated over the exposure time. (author)

  15. Shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Bearinger, Jane P.

    2017-08-29

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  16. Shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  17. Role of non-equilibrium conformations on driven polymer translocation.

    Science.gov (United States)

    Katkar, H H; Muthukumar, M

    2018-01-14

    One of the major theoretical methods in understanding polymer translocation through a nanopore is the Fokker-Planck formalism based on the assumption of quasi-equilibrium of polymer conformations. The criterion for applicability of the quasi-equilibrium approximation for polymer translocation is that the average translocation time per Kuhn segment, ⟨τ⟩/N K , is longer than the relaxation time τ 0 of the polymer. Toward an understanding of conditions that would satisfy this criterion, we have performed coarse-grained three dimensional Langevin dynamics and multi-particle collision dynamics simulations. We have studied the role of initial conformations of a polyelectrolyte chain (which were artificially generated with a flow field) on the kinetics of its translocation across a nanopore under the action of an externally applied transmembrane voltage V (in the absence of the initial flow field). Stretched (out-of-equilibrium) polyelectrolyte chain conformations are deliberately and systematically generated and used as initial conformations in translocation simulations. Independent simulations are performed to study the relaxation behavior of these stretched chains, and a comparison is made between the relaxation time scale and the mean translocation time (⟨τ⟩). For such artificially stretched initial states, ⟨τ⟩/N K polymers including single stranded DNA (ssDNA), double stranded DNA (dsDNA), and synthetic polymers. Even when these data are rescaled assuming a constant effective velocity of translocation, it is found that for flexible (ssDNA and synthetic) polymers with N K Kuhn segments, the condition ⟨τ⟩/N K polymers such as ssDNA, a crossover from quasi-equilibrium to non-equilibrium behavior would occur at N K ∼ O(1000).

  18. A polarized view on DNA under tension

    Science.gov (United States)

    van Mameren, Joost; Vermeulen, Karen; Wuite, Gijs J. L.; Peterman, Erwin J. G.

    2018-03-01

    In the past decades, sensitive fluorescence microscopy techniques have contributed significantly to our understanding of the dynamics of DNA. The specific labeling of DNA using intercalating dyes has allowed for quantitative measurement of the thermal fluctuations the polymers undergo. On the other hand, recent advances in single-molecule manipulation techniques have unraveled the mechanical and elastic properties of this intricate polymer. Here, we have combined these two approaches to study the conformational dynamics of DNA under a wide range of tensions. Using polarized fluorescence microscopy in conjunction with optical-tweezers-based manipulation of YOYO-intercalated DNA, we controllably align the YOYO dyes using DNA tension, enabling us to disentangle the rapid dynamics of the dyes from that of the DNA itself. With unprecedented control of the DNA alignment, we resolve an inconsistency in reports about the tilted orientation of intercalated dyes. We find that intercalated dyes are on average oriented perpendicular to the long axis of the DNA, yet undergo fast dynamics on the time scale of absorption and fluorescence emission. In the overstretching transition of double-stranded DNA, we do not observe changes in orientation or orientational dynamics of the dyes. Only beyond the overstretching transition, a considerable depolarization is observed, presumably caused by an average tilting of the DNA base pairs. Our combined approach thus contributes to the elucidation of unique features of the molecular dynamics of DNA.

  19. Polymer nanocomposites: polymer and particle dynamics

    KAUST Repository

    Kim, Daniel

    2012-01-01

    Polymer nanocomposites containing nanoparticles smaller than the random coil size of their host polymer chains are known to exhibit unique properties, such as lower viscosity and glass transition temperature relative to the neat polymer melt. It has been hypothesized that these unusual properties result from fast diffusion of the nanostructures in the host polymer, which facilitates polymer chain relaxation by constraint release and other processes. In this study, the effects of addition of sterically stabilized inorganic nanoparticles to entangled cis-1,4-polyisoprene and polydimethylsiloxane on the overall rheology of nanocomposites are discussed. In addition, insights about the relaxation of the host polymer chains and transport properties of nanoparticles in entangled polymer nanocomposites are presented. The nanoparticles are found to act as effective plasticizers for their entangled linear hosts, and below a critical, chemistry and molecular-weight dependent particle volume fraction, lead to reduced viscosity, glass transition temperature, number of entanglements, and polymer relaxation time. We also find that the particle motions in the polymer host are hyperdiffusive and at the nanoparticle length scale, the polymer host acts like a simple, ideal fluid and the composites\\' viscosity rises with increasing particle concentration. © 2012 The Royal Society of Chemistry.

  20. Particle Interactions in DNA-laden Flows

    International Nuclear Information System (INIS)

    Bybee, M D; Miller, G H; Trebotich, D

    2005-01-01

    Microfluidic devices are becoming state-of-the-art in many significant applications including pathogen detection, continuous monitoring, and drug delivery. Numerical algorithms which can simulate flows of complex fluids within these devices are needed for their development and optimization. A method is being developed at LLNL by Trebotich et. al. [30] for simulations of DNA-laden flows in complex microscale geometries such as packed bed reactors and pillar chips. In this method an incompressible Newtonian fluid is discretized with Cartesian grid embedded boundary methods, and the DNA is represented by a bead-rod polymer model. The fluid and polymer are coupled through a body force. In its current state, polymer-surface interactions are treated as elastic collisions between beads and surface, and polymer-polymer interactions are neglected. Implementation of polymer-polymer interactions is the main objective of this work. It is achieved by two methods: (1) a rigid constraint whereby rods elastically bounce off one another, and (2) a smooth potential acting between rods. In addition, a smooth potential is also implemented for the polymer-surface interactions. Background information will also be presented as well as related work by other researchers

  1. Particle Interactions in DNA-laden Flows

    Energy Technology Data Exchange (ETDEWEB)

    Bybee, M D; Miller, G H; Trebotich, D

    2005-12-20

    Microfluidic devices are becoming state-of-the-art in many significant applications including pathogen detection, continuous monitoring, and drug delivery. Numerical algorithms which can simulate flows of complex fluids within these devices are needed for their development and optimization. A method is being developed at LLNL by Trebotich et. al. [30] for simulations of DNA-laden flows in complex microscale geometries such as packed bed reactors and pillar chips. In this method an incompressible Newtonian fluid is discretized with Cartesian grid embedded boundary methods, and the DNA is represented by a bead-rod polymer model. The fluid and polymer are coupled through a body force. In its current state, polymer-surface interactions are treated as elastic collisions between beads and surface, and polymer-polymer interactions are neglected. Implementation of polymer-polymer interactions is the main objective of this work. It is achieved by two methods: (1) a rigid constraint whereby rods elastically bounce off one another, and (2) a smooth potential acting between rods. In addition, a smooth potential is also implemented for the polymer-surface interactions. Background information will also be presented as well as related work by other researchers.

  2. Modeling DNA

    Science.gov (United States)

    Robertson, Carol

    2016-01-01

    Deoxyribonucleic acid (DNA) is life's most amazing molecule. It carries the genetic instructions that almost every organism needs to develop and reproduce. In the human genome alone, there are some three billion DNA base pairs. The most difficult part of teaching DNA structure, however, may be getting students to visualize something as small as a…

  3. Evolution of sequence-defined highly functionalized nucleic acid polymers

    Science.gov (United States)

    Chen, Zhen; Lichtor, Phillip A.; Berliner, Adrian P.; Chen, Jonathan C.; Liu, David R.

    2018-03-01

    The evolution of sequence-defined synthetic polymers made of building blocks beyond those compatible with polymerase enzymes or the ribosome has the potential to generate new classes of receptors, catalysts and materials. Here we describe a ligase-mediated DNA-templated polymerization and in vitro selection system to evolve highly functionalized nucleic acid polymers (HFNAPs) made from 32 building blocks that contain eight chemically diverse side chains on a DNA backbone. Through iterated cycles of polymer translation, selection and reverse translation, we discovered HFNAPs that bind proprotein convertase subtilisin/kexin type 9 (PCSK9) and interleukin-6, two protein targets implicated in human diseases. Mutation and reselection of an active PCSK9-binding polymer yielded evolved polymers with high affinity (KD = 3 nM). This evolved polymer potently inhibited the binding between PCSK9 and the low-density lipoprotein receptor. Structure-activity relationship studies revealed that specific side chains at defined positions in the polymers are required for binding to their respective targets. Our findings expand the chemical space of evolvable polymers to include densely functionalized nucleic acids with diverse, researcher-defined chemical repertoires.

  4. Injection molded nanofluidic chips: Fabrication method and functional tests using single-molecule DNA experiments

    DEFF Research Database (Denmark)

    Utko, Pawel; Persson, Karl Fredrik; Kristensen, Anders

    2011-01-01

    We demonstrate that fabrication of nanofluidic systems can be greatly simplified by injection molding of polymers. We functionally test our devices by single-molecule DNA experiments in nanochannels.......We demonstrate that fabrication of nanofluidic systems can be greatly simplified by injection molding of polymers. We functionally test our devices by single-molecule DNA experiments in nanochannels....

  5. Microgel polymer composite fibres

    OpenAIRE

    Kehren, Dominic

    2014-01-01

    In this thesis some novel ideas and advancements in the field of polymer composite fibres, specifically microgel-based polymer composite fibres have been achieved. The main task was to investigate and understand the electrospinning process of microgels and polymers and the interplay of parameter influences, in order to fabricate reproducible and continuously homogenous composite fibres. The main aim was to fabricate a composite material which combines the special properties of polymer fibres ...

  6. Thermosetting Phthalocyanine Polymers

    Science.gov (United States)

    Fohlen, G.; Parker, J.; Achar, B.

    1985-01-01

    Group of phthalocyanine polymers resist thermal degradation. Polymers expected semiconducting. Principal applications probably in molded or laminated parts that have to withstand high temperatures. Polymers made from either of two classes of monomer: Bisphthalonitriles with imide linkages or Bisphthalonitriles with ester-imide linkages.

  7. based gel polymer electrolytes

    Indian Academy of Sciences (India)

    (PVdF) as a host polymer, lithium perchlorate (LiClO4), lithium triflate ... TG/DTA studies showed the thermal stability of the polymer electrolytes. .... are observed while comparing pure XRD spectra with .... batteries as its operating temperature is normally in the .... chain ion movements and the conductivity of the polymer.

  8. Aerogel / Polymer Composite Materials

    Science.gov (United States)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Roberson, Luke B. (Inventor); Clayton, LaNetra M. (Inventor)

    2017-01-01

    The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

  9. Encounter times of chromatin loci influenced by polymer decondensation

    Science.gov (United States)

    Amitai, A.; Holcman, D.

    2018-03-01

    The time for a DNA sequence to find its homologous counterpart depends on a long random search inside the cell nucleus. Using polymer models, we compute here the mean first encounter time (MFET) between two sites located on two different polymer chains and confined locally by potential wells. We find that reducing tethering forces acting on the polymers results in local decondensation, and numerical simulations of the polymer model show that these changes are associated with a reduction of the MFET by several orders of magnitude. We derive here new asymptotic formula for the MFET, confirmed by Brownian simulations. We conclude from the present modeling approach that the fast search for homology is mediated by a local chromatin decondensation due to the release of multiple chromatin tethering forces. The present scenario could explain how the homologous recombination pathway for double-stranded DNA repair is controlled by its random search step.

  10. Platinated DNA oligonucleotides: new probes forming ultrastable conjugates with graphene oxide

    Science.gov (United States)

    Wang, Feng; Liu, Juewen

    2014-05-01

    Metal containing polymers have expanded the property of polymers by involving covalently associated metal complexes. DNA is a special block copolymer. While metal ions are known to influence DNA, little is explored on its polymer property when strong metal complexes are associated. In this work, we study cisplatin modified DNA as a new polymer and probe. Out of the complexes formed between cisplatin-A15, HAuCl4-A15, Hg2+-T15 and Ag+-C15, only the cisplatin adduct is stable under the denaturing gel electrophoresis condition. Each Pt-nucleobase bond gives a positive charge and thus makes DNA a zwitterionic polymer. This allows ultrafast adsorption of DNA by graphene oxide (GO) and the adsorbed complex is highly stable. Non-specific DNA, protein, surfactants and thiolated compounds cannot displace platinated DNA from GO, while non-modified DNA is easily displaced in most cases. The stable GO/DNA conjugate is further tested for surface hybridization. This is the first demonstration of using metallated DNA as a polymeric material for interfacing with nanoscale materials.Metal containing polymers have expanded the property of polymers by involving covalently associated metal complexes. DNA is a special block copolymer. While metal ions are known to influence DNA, little is explored on its polymer property when strong metal complexes are associated. In this work, we study cisplatin modified DNA as a new polymer and probe. Out of the complexes formed between cisplatin-A15, HAuCl4-A15, Hg2+-T15 and Ag+-C15, only the cisplatin adduct is stable under the denaturing gel electrophoresis condition. Each Pt-nucleobase bond gives a positive charge and thus makes DNA a zwitterionic polymer. This allows ultrafast adsorption of DNA by graphene oxide (GO) and the adsorbed complex is highly stable. Non-specific DNA, protein, surfactants and thiolated compounds cannot displace platinated DNA from GO, while non-modified DNA is easily displaced in most cases. The stable GO/DNA conjugate

  11. Polymer Based Biosensors for Medical Applications

    DEFF Research Database (Denmark)

    Cherré, Solène; Rozlosnik, Noemi

    2015-01-01

    , environmental monitoring and food safety. The detected element varies from a single molecule (such as glucose), a biopolymer (such as DNA or a protein) to a whole organism (such as bacteria). Due to their easy use and possible miniaturization, biosensors have a high potential to come out of the lab...... and be available for use by everybody. To fulfil these purposes, polymers represent very appropriate materials. Many nano- and microfabrication methods for polymers are available, allowing a fast and cheap production of devices. This chapter will present the general concept of a biosensor in a first part......The objective of this chapter is to give an overview about the newest developments in biosensors made of polymers for medical applications. Biosensors are devices that can recognize and detect a target with high selectivity. They are widely used in many fields such as medical diagnostic...

  12. Electroluminescence of Multicomponent Conjugated Polymers. 1. Roles of Polymer/Polymer Interfaces in Emission Enhancement and Voltage-Tunable Multicolor Emission in Semiconducting Polymer/Polymer Heterojunctions

    National Research Council Canada - National Science Library

    Zhang, Xuejun, Ph.D

    1999-01-01

    Effects of the electronic structure of polymer/polymer interfaces on the electroluminescence efficiency and tunable multicolor emission of polymer heterojunction light-emitting diodes were explored...

  13. Capturing a DNA duplex under near-physiological conditions

    Science.gov (United States)

    Zhang, Huijuan; Xu, Wei; Liu, Xiaogang; Stellacci, Francesco; Thong, John T. L.

    2010-10-01

    We report in situ trapping of a thiolated DNA duplex with eight base pairs into a polymer-protected gold nanogap device under near-physiological conditions. The double-stranded DNA was captured by electrophoresis and covalently attached to the nanogap electrodes through sulfur-gold bonding interaction. The immobilization of the DNA duplex was confirmed by direct electrical measurements under near-physiological conditions. The conductance of the DNA duplex was estimated to be 0.09 μS. We also demonstrate the control of DNA dehybridization by heating the device to temperatures above the melting point of the DNA.

  14. Nanoporous polymer electrolyte

    Science.gov (United States)

    Elliott, Brian [Wheat Ridge, CO; Nguyen, Vinh [Wheat Ridge, CO

    2012-04-24

    A nanoporous polymer electrolyte and methods for making the polymer electrolyte are disclosed. The polymer electrolyte comprises a crosslinked self-assembly of a polymerizable salt surfactant, wherein the crosslinked self-assembly includes nanopores and wherein the crosslinked self-assembly has a conductivity of at least 1.0.times.10.sup.-6 S/cm at 25.degree. C. The method of making a polymer electrolyte comprises providing a polymerizable salt surfactant. The method further comprises crosslinking the polymerizable salt surfactant to form a nanoporous polymer electrolyte.

  15. Polymer friction Molecular Dynamics

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively...... independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force....

  16. Biostable glucose permeable polymer

    DEFF Research Database (Denmark)

    2017-01-01

    A new biostable glucose permeable polymer has been developed which is useful, for example, in implantable glucose sensors. This biostable glucose permeable polymer has a number of advantageous characteristics and, for example, does not undergo hydrolytic cleavage and degradation, thereby providing...... a composition that facilitates long term sensor stability in vivo. The versatile characteristics of this polymer allow it to be used in a variety of contexts, for example to form the body of an implantable glucose sensor. The invention includes the polymer composition, sensor systems formed from this polymer...

  17. Fluorination of polymers

    International Nuclear Information System (INIS)

    Du Toit, F.J.

    1991-01-01

    Polyethylene and polypropylene were reacted with elemental fluorine under carefully controlled conditions to produce fluorocarbon polymers. Fluorination of polymer films resulted in fluorination of only the outer surfaces of the films, while the reaction of elemental fluorine with powdered hydrocarbon polymers produced perfluorocarbon polymers. Existing and newly developed techniques were used to characterize the fluorinated polymers. It was shown that the degree of fluorination was influenced by the surface area of the hydrocarbon material, the concentration, of the fluorine gas, and the time and temperature of fluorination. A fluidized-bed reactor used for the fluorination of polymer powders effectively increased the reaction rate. The surface tension and the oxygen permeability of the fluorinated polymers were studied. The surface tension of hydrocarbon polymers was not influenced by different solvents, but the surface tension of fluorinated polymers was affected by the type of solvent that was used. There were indications that the surface tension was affected by oxygen introduced into the polymer surface during fluorination. Fluorination lowered the permeability of oxygen through hydrocarbon polymers. 55 refs., 51 figs., 26 tabs

  18. Advanced polymers in medicine

    CERN Document Server

    Puoci, Francesco

    2014-01-01

    The book provides an up-to-date overview of the diverse medical applications of advanced polymers. The book opens by presenting important background information on polymer chemistry and physicochemical characterization of polymers. This serves as essential scientific support for the subsequent chapters, each of which is devoted to the applications of polymers in a particular medical specialty. The coverage is broad, encompassing orthopedics, ophthalmology, tissue engineering, surgery, dentistry, oncology, drug delivery, nephrology, wound dressing and healing, and cardiology. The development of polymers that enhance the biocompatibility of blood-contacting medical devices and the incorporation of polymers within biosensors are also addressed. This book is an excellent guide to the recent advances in polymeric biomaterials and bridges the gap between the research literature and standard textbooks on the applications of polymers in medicine.

  19. Antiviral Polymer Therapeutics

    DEFF Research Database (Denmark)

    Smith, Anton Allen Abbotsford

    2014-01-01

    polymerized in a controlled manner with carrier monomers of historically proven biocompatible polymers. The carrier polymers, the loading of ribavirin as well as the size of the polymer were varied systematically with the aid of an automated synthesis platform. These polymers were tested in a cellular assay...... of reversible-addition-fragmentation chain transfer polymerization, which not only controls the size of polymer, but also allows the introduction of a terminal amine on the polymer which can be used for further conjugation. This has allowed for not only fluorescent labeling of the polymer, but also protein...... is mediated through specific transporters, it is thought that the accumulation can be alleviated through the attachment of ribavirin to a macromolecule. To this end, ribavirin was enzymatically modified into a monomer compatible with controlled polymerization techniques. The ribavirin monomers were...

  20. Polymer reaction engineering, an integrated approach

    NARCIS (Netherlands)

    Meyer, T.; Keurentjes, J.T.F.; Meyer, T.; Keurentjes, J.T.F.

    2005-01-01

    Summary This chapter contains sections titled: Polymer Materials A Short History of Polymer Reaction Engineering The Position of Polymer Reaction Engineering Toward Integrated Polymer Reaction Engineering The Disciplines in Polymer Reaction Engineering The Future: Product-inspired Polymer Reaction

  1. DNA Based Electrochromic and Photovoltaic Cells

    Science.gov (United States)

    2012-01-01

    using deoxyribonucleic acid complex as an electron blocking layer App. Phys. Lett. 88 (2006) 171109. 23. F.H.C. Crick , J.D. Watson . The complementary...9550-09-1-0647 final 01-09-2009 ; 30-11-2011 DNA Based Electrochromic and Photovoltaic Cells FA 9550-09-1-0647 Pawlicka, Agnieszka, J. Instituto de...Available. DNA is an abundant natural product with very good biodegradation properties and can be used to obtain gel polymer electrolytes (GPEs) with high

  2. Novel DNA materials and their applications.

    Science.gov (United States)

    Yang, Dayong; Campolongo, Michael J; Nhi Tran, Thua Nguyen; Ruiz, Roanna C H; Kahn, Jason S; Luo, Dan

    2010-01-01

    The last two decades have witnessed the exponential development of DNA as a generic material instead of just a genetic material. The biological function, nanoscale geometry, biocompatibility, biodegradability, and molecular recognition capacity of DNA make it a promising candidate for the construction of novel functional nanomaterials. As a result, DNA has been recognized as one of the most appealing and versatile nanomaterial building blocks. Scientists have used DNA in this way to construct various amazing nanostructures, such as ordered lattices, origami, supramolecular assemblies, and even three-dimensional objects. In addition, DNA has been utilized as a guide and template to direct the assembly of other nanomaterials including nanowires, free-standing membranes, and crystals. Furthermore, DNA can also be used as structural components to construct bulk materials such as DNA hydrogels, demonstrating its ability to behave as a unique polymer. Overall, these novel DNA materials have found applications in various areas in the biomedical field in general, and nanomedicine in particular. In this review, we summarize the development of DNA assemblies, describe the innovative progress of multifunctional and bulk DNA materials, and highlight some real-world nanomedical applications of these DNA materials. We also show our insights throughout this article for the future direction of DNA materials. © 2010 John Wiley & Sons, Inc.

  3. DNA Camouflage

    Science.gov (United States)

    2016-01-08

    1 DNA Camouflage Supplementary Information Bijan Zakeri1,2*, Timothy K. Lu1,2*, Peter A. Carr2,3* 1Department of Electrical Engineering and...ll.mit.edu). Distribution A: Public Release   2 Supplementary Figure 1 DNA camouflage with the 2-state device. (a) In the presence of Cre, DSD-2[α...10 1 + Cre 1 500 1,000 length (bp) chromatogram alignment template − Cre   4 Supplementary Figure 3 DNA camouflage with a switchable

  4. Star-Branched Polymers (Star Polymers)

    KAUST Repository

    Hirao, Akira; Hayashi, Mayumi; Ito, Shotaro; Goseki, Raita; Higashihara, Tomoya; Hadjichristidis, Nikolaos

    2015-01-01

    The synthesis of well-defined regular and asymmetric mixed arm (hereinafter miktoarm) star-branched polymers by the living anionic polymerization is reviewed in this chapter. In particular, much attention is being devoted to the synthetic

  5. Polymer dynamics from synthetic polymers to proteins

    Indian Academy of Sciences (India)

    Abstract. Starting from the standard model of polymer motion – the Rouse model – .... reptation and the escape processes (creep motion) from the tube. .... scattering curves from an arrangement of small mesoscopic spheres also allows a.

  6. Star-Branched Polymers (Star Polymers)

    KAUST Repository

    Hirao, Akira

    2015-09-01

    The synthesis of well-defined regular and asymmetric mixed arm (hereinafter miktoarm) star-branched polymers by the living anionic polymerization is reviewed in this chapter. In particular, much attention is being devoted to the synthetic development of miktoarm star polymers since 2000. At the present time, the almost all types of multiarmed and multicomponent miktoarm star polymers have become feasible by using recently developed iterative strategy. For example, the following well-defined stars have been successfully synthesized: 3-arm ABC, 4-arm ABCD, 5-arm ABCDE, 6-arm ABCDEF, 7-arm ABCDEFG, 6-arm ABC, 9-arm ABC, 12-arm ABC, 13-arm ABCD, 9-arm AB, 17-arm AB, 33-arm AB, 7-arm ABC, 15-arm ABCD, and 31-arm ABCDE miktoarm star polymers, most of which are quite new and difficult to synthesize by the end of the 1990s. Several new specialty functional star polymers composed of vinyl polymer segments and rigid rodlike poly(acetylene) arms, helical polypeptide, or helical poly(hexyl isocyanate) arms are introduced.

  7. Overproduction of the poly(ADP-ribose)polymerase DNA-binding domain blocks alkylation-induced DNA repair synthesis in mammalian cells.

    NARCIS (Netherlands)

    M. Molinete; W. Vermeulen (Wim); A. Bürkle; J. Mé nissier-de Murcia; J.H. Küpper; J.H.J. Hoeijmakers (Jan); G. de Murcia

    1993-01-01

    textabstractThe zinc-finger DNA-binding domain (DBD) of poly (ADP-ribose) polymerase (PARP, EC 2.4.2.30) specifically recognizes DNA strand breaks induced by various DNA-damaging agents in eukaryotes. This, in turn, triggers the synthesis of polymers of ADP-ribose linked to nuclear proteins during

  8. Effect of anchor positioning on binding and diffusion of elongated 3D DNA nanostructures on lipid membranes

    International Nuclear Information System (INIS)

    Khmelinskaia, Alena; Franquelim, Henri G; Petrov, Eugene P; Schwille, Petra

    2016-01-01

    DNA origami is a state-of-the-art technology that enables the fabrication of nano-objects with defined shapes, to which functional moieties, such as lipophilic anchors, can be attached with a nanometre scale precision. Although binding of DNA origami to lipid membranes has been extensively demonstrated, the specific requirements necessary for membrane attachment are greatly overlooked. Here, we designed a set of amphipathic rectangular-shaped DNA origami structures with varying placement and number of chol-TEG anchors used for membrane attachment. Single- and multiple-cholesteryl-modified origami nanostructures were produced and studied in terms of their membrane localization, density and dynamics. We show that the positioning of at least two chol-TEG moieties near the corners is essential to ensure efficient membrane binding of large DNA nanostructures. Quantitative fluorescence correlation spectroscopy data further confirm that increasing the number of corner-positioned chol-TEG anchors lowers the dynamics of flat DNA origami structures on freestanding membranes. Taken together, our approach provides the first evidence of the importance of the location in addition to the number of hydrophobic moieties when rationally designing minimal DNA nanostructures with controlled membrane binding. (paper)

  9. Theory of high-force DNA stretching and overstretching

    NARCIS (Netherlands)

    Storm, C.; Nelson, P.

    2003-01-01

    Single-molecule experiments on single- and double-stranded DNA have sparked a renewed interest in the force versus extension of polymers. The extensible freely jointed chain (FJC) model is frequently invoked to explain the observed behavior of single-stranded DNA, but this model does not

  10. DNA glue

    DEFF Research Database (Denmark)

    Filichev, Vyacheslav V; Astakhova, Irina V.; Malakhov, Andrei D.

    2008-01-01

    Significant alterations in thermal stability of parallel DNA triplexes and antiparallel duplexes were observed upon changing the attachment of ethynylpyrenes from para to ortho in the structure of phenylmethylglycerol inserted as a bulge into DNA (TINA). Insertions of two ortho-TINAs as a pseudo...

  11. Hyperstretching DNA

    NARCIS (Netherlands)

    Schakenraad, Koen; Biebricher, Andreas S.; Sebregts, Maarten; Ten Bensel, Brian; Peterman, Erwin J.G.; Wuite, Gijs J L; Heller, Iddo; Storm, Cornelis; Van Der Schoot, Paul

    2017-01-01

    The three-dimensional structure of DNA is highly susceptible to changes by mechanical and biochemical cues in vivo and in vitro. In particular, large increases in base pair spacing compared to regular B-DNA are effected by mechanical (over)stretching and by intercalation of compounds that are widely

  12. Artificially Engineered Protein Polymers.

    Science.gov (United States)

    Yang, Yun Jung; Holmberg, Angela L; Olsen, Bradley D

    2017-06-07

    Modern polymer science increasingly requires precise control over macromolecular structure and properties for engineering advanced materials and biomedical systems. The application of biological processes to design and synthesize artificial protein polymers offers a means for furthering macromolecular tunability, enabling polymers with dispersities of ∼1.0 and monomer-level sequence control. Taking inspiration from materials evolved in nature, scientists have created modular building blocks with simplified monomer sequences that replicate the function of natural systems. The corresponding protein engineering toolbox has enabled the systematic development of complex functional polymeric materials across areas as diverse as adhesives, responsive polymers, and medical materials. This review discusses the natural proteins that have inspired the development of key building blocks for protein polymer engineering and the function of these elements in material design. The prospects and progress for scalable commercialization of protein polymers are reviewed, discussing both technology needs and opportunities.

  13. Internally plasticised cellulose polymers

    International Nuclear Information System (INIS)

    Burnup, M.; Hayes, G.F.; Fydelor, P.J.

    1981-01-01

    Plasticised cellulose polymers comprise base polymer having a chain of β-anhydroglucose units joined by ether linkages, with at least one of said units carrying at least one chemically unreactive side chain derived from an allylic monomer or a vinyl substituted derivative of ferrocene. The side chains are normally formed by radiation grafting. These internally plasticised celluloses are useful in particular as inhibitor coatings for rocket motor propellants and in general wherever cellulose polymers are employed. (author)

  14. Characterisation of polymers, 1

    CERN Document Server

    Crompton, Roy

    2008-01-01

    This essential guide to Polymer Characterisation is a complete compendium of methodologies that have evolved for the determination of the chemical composition of polymers. This 478-page book gives an up-to-date and thorough exposition of the state-of-the-art theories and availability of instrumentation needed to effect chemical and physical analysis of polymers. This is supported by approximately 1200 references. Volume 1 covers the methodology used for the determination of metals, non-metals and organic functional groups in polymers, and for the determination of the ratio in which different m

  15. DNA probes

    International Nuclear Information System (INIS)

    Castelino, J.

    1992-01-01

    The creation of DNA probes for detection of specific nucleotide segments differs from ligand detection in that it is a chemical rather than an immunological reaction. Complementary DNA or RNA is used in place of the antibody and is labelled with 32 P. So far, DNA probes have been successfully employed in the diagnosis of inherited disorders, infectious diseases, and for identification of human oncogenes. The latest approach to the diagnosis of communicable and parasitic infections is based on the use of deoxyribonucleic acid (DNA) probes. The genetic information of all cells is encoded by DNA and DNA probe approach to identification of pathogens is unique because the focus of the method is the nucleic acid content of the organism rather than the products that the nucleic acid encodes. Since every properly classified species has some unique nucleotide sequences that distinguish it from every other species, each organism's genetic composition is in essence a finger print that can be used for its identification. In addition to this specificity, DNA probes offer other advantages in that pathogens may be identified directly in clinical specimens

  16. DNA probes

    Energy Technology Data Exchange (ETDEWEB)

    Castelino, J

    1993-12-31

    The creation of DNA probes for detection of specific nucleotide segments differs from ligand detection in that it is a chemical rather than an immunological reaction. Complementary DNA or RNA is used in place of the antibody and is labelled with {sup 32}P. So far, DNA probes have been successfully employed in the diagnosis of inherited disorders, infectious diseases, and for identification of human oncogenes. The latest approach to the diagnosis of communicable and parasitic infections is based on the use of deoxyribonucleic acid (DNA) probes. The genetic information of all cells is encoded by DNA and DNA probe approach to identification of pathogens is unique because the focus of the method is the nucleic acid content of the organism rather than the products that the nucleic acid encodes. Since every properly classified species has some unique nucleotide sequences that distinguish it from every other species, each organism`s genetic composition is in essence a finger print that can be used for its identification. In addition to this specificity, DNA probes offer other advantages in that pathogens may be identified directly in clinical specimens 10 figs, 2 tabs

  17. Binary Polymer Brushes of Strongly Immiscible Polymers.

    Science.gov (United States)

    Chu, Elza; Babar, Tashnia; Bruist, Michael F; Sidorenko, Alexander

    2015-06-17

    The phenomenon of microphase separation is an example of self-assembly in soft matter and has been observed in block copolymers (BCPs) and similar materials (i.e., supramolecular assemblies (SMAs) and homo/block copolymer blends (HBCs)). In this study, we use microphase separation to construct responsive polymer brushes that collapse to generate periodic surfaces. This is achieved by a chemical reaction between the minor block (10%, poly(4-vinylpyridine)) of the block copolymer and a substrate. The major block of polystyrene (PS) forms mosaic-like arrays of grafted patches that are 10-20 nm in size. Depending on the nature of the assembly (SMA, HBC, or neat BCP) and annealing method (exposure to vapors of different solvents or heating above the glass transition temperature), a range of "mosaic" brushes with different parameters can be obtained. Successive grafting of a secondary polymer (polyacrylamide, PAAm) results in the fabrication of binary polymer brushes (BPBs). Upon being exposed to specific selective solvents, BPBs may adopt different conformations. The surface tension and adhesion of the binary brush are governed by the polymer occupying the top stratum. The "mosaic" brush approach allows for a combination of strongly immiscible polymers in one brush. This facilitates substantial contrast in the surface properties upon switching, previously only possible for substrates composed of predetermined nanostructures. We also demonstrate a possible application of such PS/PAAm brushes in a tunable bioadhesion-bioadhesive (PS on top) or nonbioadhesive (PAAm on top) surface as revealed by Escherichia coli bacterial seeding.

  18. Triazene-Based Traceless Linkers for DNA-Directed Chemistry and Development of Methods for Linking Nanomaterials to DNA Origami

    DEFF Research Database (Denmark)

    Hejesen, Christian

    2013-01-01

    , kan triazen linkeren ydermere introducere ny kemi på en DNA streng ved kløvning. Det andet projekt, der er beskrevet i dette kapitel, omhandler de indledende studier og resultater for en DNA-dirigeret palladium katalyseret Suzuki-Miyaura krydskobling. I kapitel 3 bliver DNA origami feltet kort...... med ren DNA bliver kulstof-nanorørene dispergeret med syntetisk polymer der indeholder DNA. Denne polymer gør det muligt at binde kulstof-nanorørene på en DNA origami, der så kan analyseret ved hjælp af atomar kraftmikroskopi. Kapitel 4 omhandler et projekt omhandler arbejde der er udført ved Arizona...

  19. Photoreactivity of chlorpromazine with native DNA in an aqueous solution

    International Nuclear Information System (INIS)

    Fujita, Hitoshi; Yanagisawa, Fukuko; Endo, Akira; Suzuki, Kenshi

    1980-01-01

    Near-UV irradiation of a mixture of chlorpromazine and native DNA caused irreversible binding of the drug or its photoproduct(s) to DNA and double strand break of DNA. When the irradiation was performed in a reaction mixture with a low salt concentration, much more photobinding occurred. Accompanying these effects, the maximum hyperchromicity of DNA at a high temperature was decreased. This can be explained by either a partial denaturation or an inhibition of melting by a formation of complex between double helical DNA and a promazine polymer. (author)

  20. Polymer gels and networks

    National Research Council Canada - National Science Library

    Osada, Yoshihito; Khokhlov, A. R

    2002-01-01

    ... or magnetic field, etc.). It was realized that not only can polymer gels absorb and hold a considerable volume of liquids, but they can also be forced to expel the absorbed liquid in a controlled manner. Of particular interest are hydrogels, i.e., polymer gels, which swell extensively in water. The most common hydrogels are polyelectrolyte gels: ...

  1. SANS studies of polymers

    International Nuclear Information System (INIS)

    Wignall, G.D.

    1985-01-01

    Some information provided by the application of small-angle neutron scattering concerning polymer structure is reviewed herein. Information about the polymer structure as examined in H 2 O/D 2 O mixtures is also provided. Examples of results of experiments performed at the National Center for Small-Angle Scattering Research are included

  2. Polymer based tunneling sensor

    Science.gov (United States)

    Cui, Tianhong (Inventor); Wang, Jing (Inventor); Zhao, Yongjun (Inventor)

    2006-01-01

    A process for fabricating a polymer based circuit by the following steps. A mold of a design is formed through a lithography process. The design is transferred to a polymer substrate through a hot embossing process. A metal layer is then deposited over at least part of said design and at least one electrical lead is connected to said metal layer.

  3. Polymers for Combating Biocorrosion

    Directory of Open Access Journals (Sweden)

    Jing Guo

    2018-03-01

    Full Text Available Biocorrosion has been considered as big trouble in many industries and marine environments due to causing of great economic loss. The main disadvantages of present approaches to prevent corrosion include being limited by environmental factors, being expensive, inapplicable to field, and sometimes inefficient. Studies show that polymer coatings with anticorrosion and antimicrobial properties have been widely accepted as a novel and effective approach to prevent biocorrosion. The main purpose of this review is to summarize up the progressive status of polymer coatings used for combating microbial corrosion. Polymers used to synthesize protective coatings are generally divided into three categories: (i traditional polymers incorporated with biocides, (ii antibacterial polymers containing quaternary ammonium compounds, and (iii conductive polymers. The strategies to synthesize polymer coatings resort mainly to grafting antibacterial polymers from the metal substrate surface using novel surface-functionalization approaches, such as free radical polymerization, chemically oxidative polymerization, and surface-initiated atom transfer radical polymerization, as opposed to the traditional approaches of dip coating or spin coating.

  4. Polymer light emitting diodes

    International Nuclear Information System (INIS)

    Gautier-Thianche, Emmmanuelle

    1998-01-01

    We study sandwich type semiconducting polymer light emitting diodes; anode/polymer/cathode. ITO is selected as anode, this polymer is a blend of a commercially available polymer with a high hole transport ability: polyvinyl-carbazole and a laser dye: coumarin-515. Magnesium covered with silver is chosen for the anode. We study the influence of polymer thickness and coumarin doping ratio on electroluminescence spectrum, electric characteristics and quantum efficiency. An important drawback is that diodes lifetime remains low. In the second part of our study we determine degradations causes with X-Ray reflectivity experiments. It may be due to ITO very high roughness. We realize a new type of planar electroluminescent device: a channel type electroluminescent device in which polymer layer is inserted into an aluminium channel. Such a device is by far more stable than using classical sandwich structures with the same polymer composition: indeed, charges are generated by internal-field ionization and there is no injection from the electrode to the polymer. This avoids electrochemical reactions at electrodes, thus reducing degradations routes. (author) [fr

  5. Polymers targeting habitual diseases

    Science.gov (United States)

    The use of polymeric drug conjugates mainly for the treatment for cancer therapy has been addressed, but these polymers also find their way in treatment of various lifestyle disorders like diabetes, hypertension, cardiovascular diseases etc. The focus is being laid to develop biodegradable polymer ...

  6. Stiff quantum polymers

    OpenAIRE

    Kleinert, H.

    2009-01-01

    At ultralow temperatures, polymers exhibit quantum behavior, which is calculated here for the second and fourth moments of the end-to-end distribution in the large-stiffness regime. The result should be measurable for polymers in wide optical traps.

  7. Conducting polymer hydrogels

    Czech Academy of Sciences Publication Activity Database

    Stejskal, Jaroslav

    2017-01-01

    Roč. 71, č. 2 (2017), s. 269-291 ISSN 0366-6352 R&D Projects: GA ČR(CZ) GA16-02787S Institutional support: RVO:61389013 Keywords : aerogel * conducting polymers * conductivity Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 1.258, year: 2016

  8. DNA methylation

    DEFF Research Database (Denmark)

    Williams, Kristine; Christensen, Jesper; Helin, Kristian

    2012-01-01

    DNA methylation is involved in key cellular processes, including X-chromosome inactivation, imprinting and transcriptional silencing of specific genes and repetitive elements. DNA methylation patterns are frequently perturbed in human diseases such as imprinting disorders and cancer. The recent...... discovery that the three members of the TET protein family can convert 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC) has provided a potential mechanism leading to DNA demethylation. Moreover, the demonstration that TET2 is frequently mutated in haematopoietic tumours suggests that the TET...... proteins are important regulators of cellular identity. Here, we review the current knowledge regarding the function of the TET proteins, and discuss various mechanisms by which they contribute to transcriptional control. We propose that the TET proteins have an important role in regulating DNA methylation...

  9. DNA data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Raw DNA chromatogram data produced by the ABI 373, 377, 3130 and 3730 automated sequencing machines in ABI format. These are from fish (primarily Sebastes spp.,...

  10. DNA nanotechnology

    Science.gov (United States)

    Seeman, Nadrian C.; Sleiman, Hanadi F.

    2018-01-01

    DNA is the molecule that stores and transmits genetic information in biological systems. The field of DNA nanotechnology takes this molecule out of its biological context and uses its information to assemble structural motifs and then to connect them together. This field has had a remarkable impact on nanoscience and nanotechnology, and has been revolutionary in our ability to control molecular self-assembly. In this Review, we summarize the approaches used to assemble DNA nanostructures and examine their emerging applications in areas such as biophysics, diagnostics, nanoparticle and protein assembly, biomolecule structure determination, drug delivery and synthetic biology. The introduction of orthogonal interactions into DNA nanostructures is discussed, and finally, a perspective on the future directions of this field is presented.

  11. Theory of polymer blends

    International Nuclear Information System (INIS)

    Curro, J.G.; Schweizer, K.S.

    1989-01-01

    We have recently developed a new theoretical approach to the study of polymer liquids. The theory is based on the ''reference interaction site model'' (RISM theory) of Chandler and Andersen, which has been successful in describing the structure of small molecule liquids. We have recently extended our polymer RISM theory to the case of polymer blends. In the present investigation we have applied this theory to two special binary blends: (1) the athermal mixture where we isolate structural effects, and (2) the isotopic mixture in which structurally identical polymer chains interact with dissimilar attractive interactions. By studying these two special cases we are able to obtain insights into the molecular factors which control the miscibility in polymer mixtures. 18 refs., 2 figs

  12. Ion Implantation of Polymers

    DEFF Research Database (Denmark)

    Popok, Vladimir

    2012-01-01

    The current paper presents a state-of-the-art review in the field of ion implantation of polymers. Numerous published studies of polymers modified by ion beams are analysed. General aspects of ion stopping, latent track formation and changes of structure and composition of organic materials...... are discussed. Related to that, the effects of radiothermolysis, degassing and carbonisation are considered. Specificity of depth distributions of implanted into polymers impurities is analysed and the case of high-fluence implantation is emphasised. Within rather broad topic of ion bombardment, the focus...... is put on the low-energy implantation of metal ions causing the nucleation and growth of nanoparticles in the shallow polymer layers. Electrical, optical and magnetic properties of metal/polymer composites are under the discussion and the approaches towards practical applications are overviewed....

  13. All Polymer Micropump

    DEFF Research Database (Denmark)

    Hansen, Thomas Steen

    2008-01-01

    In this thesis an all polymer micropump, and the fabrication method required to fabricate this, are examined. Polymer microfluidic. devices are of major scientific interest because they can combine complicated chemical and biological analys~s in cheap and disposable devices. The electrode system...... in the micropump is based on the conducting polymer poly(3,4 ethylenedioxythiophene) (PEDOT). The majority of the work conducted was therefore aimed at developing methods for patterning and processing PEDOT. First a method was developed, where the conducting polymer PEDOT can be integrated into non...... of the substrate, the PEDOT is integrated into the non-conductive polymer. The result is a material that retains the good conductivity of PEDOT, but gains the mechanical stability of the substrate. The best results were obtained for PEDOTjPMMA. The new mechanically stable PEDOTjPMMA was micro-patterned using clean...

  14. Polymer wear evaluation

    DEFF Research Database (Denmark)

    Lagerbon, Mikkel; Sivebæk, Ion Marius

    2012-01-01

    Polymer wear plays an increasing role in manufacturing of machine parts for e.g. medical devices. Some of these have an expected lifetime of five to eight years during which very little wear of the components is acceptable. Too much wear compromises the dosage accuracy of the device and thereby...... the safety of the patients. Prediction of the wear of polymers is complicated by the low thermal conductivity of this kind of material. It implies that any acceleration of testing conditions by increased contact pressure and/or sliding velocity will make the polymer fail due to exaggerated heat buildup....... This is not the kind of wear observed in medical devices. In the present work a method was developed capable of evaluating the wear progression in polymer-polymer contacts. The configuration of the setup is injection moulded specimens consisting of an upper part having a toroid shape and a lower flat part. The sliding...

  15. DNA expressions - A formal notation for DNA

    NARCIS (Netherlands)

    Vliet, Rudy van

    2015-01-01

    We describe a formal notation for DNA molecules that may contain nicks and gaps. The resulting DNA expressions denote formal DNA molecules. Different DNA expressions may denote the same molecule. Such DNA expressions are called equivalent. We examine which DNA expressions are minimal, which

  16. Synthetic genetic polymers capable of heredity and evolution

    DEFF Research Database (Denmark)

    Pinheiro, Vitor B; Taylor, Alexander I; Cozens, Christopher

    2012-01-01

    in and recovered from six alternative genetic polymers based on simple nucleic acid architectures not found in nature [xeno-nucleic acids (XNAs)]. We also select XNA aptamers, which bind their targets with high affinity and specificity, demonstrating that beyond heredity, specific XNAs have the capacity......Genetic information storage and processing rely on just two polymers, DNA and RNA, yet whether their role reflects evolutionary history or fundamental functional constraints is currently unknown. With the use of polymerase evolution and design, we show that genetic information can be stored...... for Darwinian evolution and folding into defined structures. Thus, heredity and evolution, two hallmarks of life, are not limited to DNA and RNA but are likely to be emergent properties of polymers capable of information storage....

  17. What Is Mitochondrial DNA?

    Science.gov (United States)

    ... DNA What is mitochondrial DNA? What is mitochondrial DNA? Although most DNA is packaged in chromosomes within ... proteins. For more information about mitochondria and mitochondrial DNA: Molecular Expressions, a web site from the Florida ...

  18. Photoluminescence in conjugated polymers

    International Nuclear Information System (INIS)

    Furst, J.E.; Laugesen, R.; Dastoor, P.; McNeill, C.

    2002-01-01

    Full text: Conjugated polymers combine the electronic and optical properties of semiconductors with the processability of polymers. They contain a sequence of alternate single and double carbon bonds so that the overlap of unhybridised p z orbitals creates a delocalised ρ system which gives semiconducting properties with p-bonding (valence) and p* -antibonding (conduction) bands. Photoluminesence (PL) in conjugated polymers results from the radiative decay of singlet excitons confined to a single chain. The present work is the first in a series of studies in our laboratory that will characterize the optical properties of conjugated polymers. The experiment involves the illumination of thin films of conjugated polymer with UV light (I=360 nm) and observing the subsequent fluorescence using a custom-built, fluorescence spectrometer. Photoluminesence spectra provide basic information about the structure of the polymer film. A typical spectrum is shown in the accompanying figure. The position of the first peak is related to the polymer chain length and resolved multiple vibronic peaks are an indication of film structure and morphology. We will also present results related to the optical degradation of these materials when exposed to air and UV light

  19. Investigation of a thiolated polymer in gene delivery

    Science.gov (United States)

    Bacalocostantis, Irene

    Thiol-containing bioreducible polymers show significant potential as delivery vectors in gene therapy, a rapidly growing field which seeks to treat genetic-based disorders by delivering functional synthetic genes to diseased cells. Studies have shown that thiolated polymers exhibit improved biodegradability and prolonged in vivo circulation times over non-thiolated polymers. However, the extent to which thiol concentrations impact the carrier's delivery potential has not been well explored. The aim of this dissertation is to investigate how relative concentrations of free thiols and disulfide crosslinks impact a polymeric carriers delivery performance with respect to DNA packaging, complex stability, cargo protection, gene release, internalization efficiency and cytotoxicity. To accomplish this goal, several fluorescent polymers containing varying concentrations of thiol groups were synthesized by conjugating thiol-pendant chains onto the primary amines of cationic poly(allylamine). In vitro delivery assays and characterization techniques were employed to assess the effect of thiols in gene delivery.

  20. DNA based radiological dosimetry technology

    International Nuclear Information System (INIS)

    Diaz Quijada, Gerardo A.; Roy, Emmanuel; Veres, Teodor; Dumoulin, Michel M.; Vachon, Caroline; Blagoeva, Rosita; Pierre, Martin

    2008-01-01

    Full text: The purpose of this project is to develop a personal and wearable dosimeter using a highly-innovative approach based on the specific recognition of DNA damage with a polymer hybrid. Our biosensor will be sensitive to breaks in nucleic acid macromolecules and relevant to mixed-field radiation. The dosimeter proposed will be small, field deployable and will sense damages for all radiation types at the DNA level. The generalized concept for the novel-based radiological dosimeter: 1) Single or double stranded oligonucleotide is immobilized on surface; 2) Single stranded has higher cross-section for fragmentation; 3) Double stranded is more biological relevant; 4) Radiation induces fragmentation; 5) Ultra-sensitive detection of fragments provides radiation dose. Successful efforts have been made towards a proof-of-concept personal wearable DNA-based dosimeter that is appropriate for mixed-field radiation. The covalent immobilization of oligonucleotides on large areas of plastic surfaces has been demonstrated and corroborated spectroscopically. The surface concentration of DNA was determined to be 8 x 1010 molecules/cm 2 from a Ce(IV) catalyzed hydrolysis study of a fluorescently labelled oligonucleotide. Current efforts are being directed at studying radiation induced fragmentation of DNA followed by its ultra-sensitive detection via a novel method. In addition, proof-of-concept wearable personal devices and a detection platform are presently being fabricated. (author)

  1. Extração de DNA de materiais de arquivo e fontes escassas para utilização em reação de polimerização em cadeia (PCR Methods of DNA extraction from archived materials and rare sources for utilization in polymer chain reaction

    Directory of Open Access Journals (Sweden)

    Jaqueline A. Barea

    2004-12-01

    Full Text Available Este trabalho visou a comparação de cinco métodos diferentes de extração de DNA de materiais de arquivo (tecidos incluídos em parafina, esfregaços de sangue periférico - corados e não corados com Leishman, lâminas com mielogramas, gotas de sangue em Guthrie Card e de fontes escassas (células bucais, um e três bulbos capilares e 2 mL de urina, para que fossem avaliadas a facilidade de aplicação e a facilidade de amplificação deste DNA pela técnica da reação de polimerização em cadeia (PCR. Os métodos incluíram digestão por proteinase K, seguida ou não por purificação com fenol/clorofórmio; Chelex 100® (BioRad; Insta Gene® (BioRad e fervura em água estéril. O DNA obtido foi testado para amplificação de três fragmentos gênicos: Brain-derived neutrophic factor (764 pb, Factor V Leiden (220 pb e Abelson (106 pb. De acordo com o comprimento do fragmento gênico estudado, da fonte potencial de DNA e do método de extração utilizado, os resultados caracterizaram o melhor caminho para padronização de procedimentos técnicos a serem incluídos no manual de Procedimentos Operacionais Padrão do Laboratório de Biologia Molecular do Hemocentro - HC - Unesp - Botucatu.The present work aimed at comparing five different methods of DNA extraction of samples from archived materials (paraffin-embedded tissues, peripheral blood smears - stained or not with Leishman, aspired bone marrow smears and Guthrie card bloodspots and from rare sources (oral cells, one and three capillary bulbs, 2 mL of urine, to evaluate the ease of application and the possibility of amplification of this DNA by the polymerization chain reaction (PCR technique. The methods included proteinase K digestion - followed or not by phenol/chloroform purification, Chelex 100® (BioRad, InstaGene® (BioRad and boiling in the sterile water. The DNA obtained was tested for amplification of three genic fragments: the brain-derived neutrophic factor gene (764 bp

  2. Polymer translocation under a pulling force: Scaling arguments and threshold forces

    Science.gov (United States)

    Menais, Timothée

    2018-02-01

    DNA translocation through nanopores is one of the most promising strategies for next-generation sequencing technologies. Most experimental and numerical works have focused on polymer translocation biased by electrophoresis, where a pulling force acts on the polymer within the nanopore. An alternative strategy, however, is emerging, which uses optical or magnetic tweezers. In this case, the pulling force is exerted directly at one end of the polymer, which strongly modifies the translocation process. In this paper, we report numerical simulations of both linear and structured (mimicking DNA) polymer models, simple enough to allow for a statistical treatment of the pore structure effects on the translocation time probability distributions. Based on extremely extended computer simulation data, we (i) propose scaling arguments for an extension of the predicted translocation times τ ˜N2F-1 over the moderate forces range and (ii) analyze the effect of pore size and polymer structuration on translocation times τ .

  3. Effect of thiol pendant conjugates on plasmid DNA binding, release, and stability of polymeric delivery vectors.

    Science.gov (United States)

    Bacalocostantis, Irene; Mane, Viraj P; Kang, Michael S; Goodley, Addison S; Muro, Silvia; Kofinas, Peter

    2012-05-14

    Polymers have attracted much attention as potential gene delivery vectors due to their chemical and structural versatility. However, several challenges associated with polymeric carriers, including low transfection efficiencies, insufficient cargo release, and high cytotoxicity levels have prevented clinical implementation. Strong electrostatic interactions between polymeric carriers and DNA cargo can prohibit complete cargo release within the cell. As a result, cargo DNA never reaches the cell's nucleus where gene expression takes place. In addition, highly charged cationic polymers have been correlated with high cytotoxicity levels, making them unsuitable carriers in vivo. Using poly(allylamine) (PAA) as a model, we investigated how pH-sensitive disulfide cross-linked polymer networks can improve the delivery potential of cationic polymer carriers. To accomplish this, we conjugated thiol-terminated pendant chains onto the primary amines of PAA using 2-iminothiolane, developing three new polymer vectors with 5, 13, or 20% thiol modification. Unmodified PAA and thiol-conjugated polymers were tested for their ability to bind and release plasmid DNA, their capacity to protect genetic cargo from enzymatic degradation, and their potential for endolysosomal escape. Our results demonstrate that polymer-plasmid complexes (polyplexes) formed by the 13% thiolated polymer demonstrate the greatest delivery potential. At high N/P ratios, all thiolated polymers (but not unmodified counterparts) were able to resist decomplexation in the presence of heparin, a negatively charged polysaccharide used to mimic in vivo polyplex-protein interactions. Further, all thiolated polymers exhibited higher buffering capacities than unmodified PAA and, therefore, have a greater potential for endolysosomal escape. However, 5 and 20% thiolated polymers exhibited poor DNA binding-release kinetics, making them unsuitable carriers for gene delivery. The 13% thiolated polymers, on the other hand

  4. Biomedical applications of polymers

    CERN Document Server

    Gebelein, C G

    1991-01-01

    The biomedical applications of polymers span an extremely wide spectrum of uses, including artificial organs, skin and soft tissue replacements, orthopaedic applications, dental applications, and controlled release of medications. No single, short review can possibly cover all these items in detail, and dozens of books andhundreds of reviews exist on biomedical polymers. Only a few relatively recent examples will be cited here;additional reviews are listed under most of the major topics in this book. We will consider each of the majorclassifications of biomedical polymers to some extent, inclu

  5. SANS studies of polymers

    International Nuclear Information System (INIS)

    Wignall, G.D.

    1984-10-01

    Before small-angle neutron scattering (SANS), chain conformation studies were limited to light and small angle x-ray scattering techniques, usually in dilute solution. SANS from blends of normal and labeled molecules could give direct information on chain conformation in bulk polymers. Water-soluble polymers may be examined in H 2 O/D 2 O mixtures using contrast variation methods to provide further information on polymer structure. This paper reviews some of the information provided by this technique using examples of experiments performed at the National Center for Small-Angle Scattering Research (NCSASR)

  6. Development of Silicate Polymers

    DEFF Research Database (Denmark)

    Søgaard, Erik Gydesen; Simonsen, Morten Enggrob

      The development of inorganic polymers is a new promising technology that may be used in many applications. The syntheses of inorganic polymers are normally carried out either by mixing an amorphous material for example silicium dioxide with a mineral base or dissolving metal oxids or metal...... hydroxide in acid and increase pH to saturation of the metal hydroxide. It is assumed that the syntheses of the inorganic polymer are carried out through polymerisation of oligomers (dimer, trimer) which provide the actual unit structures of the three dimensional macromolecular structure. In this work...

  7. Soluble porphyrin polymers

    Science.gov (United States)

    Gust, Jr., John Devens; Liddell, Paul Anthony

    2015-07-07

    Porphyrin polymers of Structure 1, where n is an integer (e.g., 1, 2, 3, 4, 5, or greater) ##STR00001## are synthesized by the method shown in FIGS. 2A and 2B. The porphyrin polymers of Structure 1 are soluble in organic solvents such as 2-MeTHF and the like, and can be synthesized in bulk (i.e., in processes other than electropolymerization). These porphyrin polymers have long excited state lifetimes, making the material suitable as an organic semiconductor for organic electronic devices including transistors and memories, as well as solar cells, sensors, light-emitting devices, and other opto-electronic devices.

  8. Statistical properties of curved polymer

    Indian Academy of Sciences (India)

    respective ground states decide the conformational statistics of the polymer. For semiflexible polymers, the relevant non-dimensional quantity is lp/L, where lp is the persistence length (which is proportional to the bending modulus k) and L is the contour length of the polymer. In the limit, lp/L ≪ 1, the polymer behaves as.

  9. Sustained delivery of plasmid DNA from polymeric scaffolds for tissue engineering.

    Science.gov (United States)

    Storrie, Hannah; Mooney, David J

    2006-07-07

    The encapsulation of DNA into polymeric depot systems can be used to spatially and temporally control DNA release, leading to a sustained, local delivery of therapeutic factors for tissue regeneration. Prior to encapsulation, DNA may be condensed with cationic polymers to decrease particle size, protect DNA from degradation, promote interaction with cell membranes, and facilitate endosomal release via the proton sponge effect. DNA has been encapsulated with either natural or synthetic polymers to form micro- and nanospheres, porous scaffolds and hydrogels for sustained DNA release and the polymer physical and chemical properties have been shown to influence transfection efficiency. Polymeric depot systems have been applied for bone, skin, and nerve regeneration as well as therapeutic angiogenesis, indicating the broad applicability of these systems for tissue engineering.

  10. Electroactive polymers for sensing

    Science.gov (United States)

    2016-01-01

    Electromechanical coupling in electroactive polymers (EAPs) has been widely applied for actuation and is also being increasingly investigated for sensing chemical and mechanical stimuli. EAPs are a unique class of materials, with low-moduli high-strain capabilities and the ability to conform to surfaces of different shapes. These features make them attractive for applications such as wearable sensors and interfacing with soft tissues. Here, we review the major types of EAPs and their sensing mechanisms. These are divided into two classes depending on the main type of charge carrier: ionic EAPs (such as conducting polymers and ionic polymer–metal composites) and electronic EAPs (such as dielectric elastomers, liquid-crystal polymers and piezoelectric polymers). This review is intended to serve as an introduction to the mechanisms of these materials and as a first step in material selection for both researchers and designers of flexible/bendable devices, biocompatible sensors or even robotic tactile sensing units. PMID:27499846

  11. Superabsorbent polymer; Kokyushusei porima

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, M. [Sanyo Kasei Kogyo K.K., Tokyo (Japan)

    1996-07-20

    Superabsorbent polymer (SAP) which has the absorbing ability from several hundreds to thousand times of the dead weight possesses many other functions in addition to the absorbing function, and studies on its application to various fields have been carried on very actively. Particularly, about 90% of the demand is for the application to body fluid absorber in the fields of sanitary materials. Basic water absorption mechanism, kinds, production methods, special features and applied cases of superabsorbent polymer are introduced. SAP is structured by loosely bridged water soluble polymer, particularly polymer electrolyte, to provide water unsoluble and water swelling properties. The kinds and production methods of SAP are described. SAP has respiration property in addition to the high water absorbing power and water holding ability. It has carboxyl ions, and has ammonia absorption ability and polyvalent metal ion adsorption ability. Paper diapers, water holding materials for soil, and cold reserving materials are discussed as examples of SAP application. 3 refs., 2 figs., 1 tab.

  12. Rheology of Supramolecular Polymers

    DEFF Research Database (Denmark)

    Shabbir, Aamir

    Supramolecular polymers are a broad class of materials that include all polymerscapable of associating via secondary interactions. These materials represent an emerging class of systems with superior versatility compared to classical polymers with applications in food stuff, coatings, cost...... efficient processes or biomedical areas. Design and development of supramolecular polymers using ionic, hydrogen bonding or transition metal complexes with tailored properties requires deep understanding of dynamics both in linear and non-linear deformations. While linear rheology is important to understand...... the dynamics under equilibrium conditions, extensional rheology is relevant during the processing or in the usage of polymers utilizing supramolecular associations for example, acrylic based pressure sensitive adhesives are subjected to extensional deformations during the peeling where strain hardening...

  13. Piezoelectricity in polymers

    International Nuclear Information System (INIS)

    Kepler, R.G.; Anderson, R.A.

    1980-01-01

    Piezoelectricity and related properties of polymers are reviewed. After presenting a historical overview of the field, the mathematical basis of piezo- and pyroelectricity is summarized. We show how the experimentally measured quantities are related to the changes in polarization and point out the serious inequlity between direct and converse piezoelectric coefficients in polymers. Theoretical models of the various origins of piezo- and pyroelectricity, which include piezoelectricity due to inhomogeneous material properties and strains, are reviewed. Relaxational effects are also considered. Experimental techniques are examined and the results for different materials are presented. Because of the considerable work in recent years polyimylidene fluoride, this polymer receives the majority of the attention. The numerous applications of piezo-and pyroelectric polymers are mentioned. This article concludes with a discussion of the possible role of piezo- and pyroelectricity in biological system

  14. Conjugated Polymer Solar Cells

    National Research Council Canada - National Science Library

    Paraschuk, Dmitry Y

    2006-01-01

    This report results from a contract tasking Moscow State University as follows: Conjugated polymers are promising materials for many photonics applications, in particular, for photovoltaic and solar cell devices...

  15. Polymers for Protein Conjugation

    Directory of Open Access Journals (Sweden)

    Gianfranco Pasut

    2014-01-01

    Full Text Available Polyethylene glycol (PEG at the moment is considered the leading polymer for protein conjugation in view of its unique properties, as well as to its low toxicity in humans, qualities which have been confirmed by its extensive use in clinical practice. Other polymers that are safe, biodegradable and custom-designed have, nevertheless, also been investigated as potential candidates for protein conjugation. This review will focus on natural polymers and synthetic linear polymers that have been used for protein delivery and the results associated with their use. Genetic fusion approaches for the preparation of protein-polypeptide conjugates will be also reviewed and compared with the best known chemical conjugation ones.

  16. Reactive polymer fused deposition manufacturing

    Science.gov (United States)

    Kunc, Vlastimil; Rios, Orlando; Love, Lonnie J.; Duty, Chad E.; Johs, Alexander

    2017-05-16

    Methods and compositions for additive manufacturing that include reactive or thermosetting polymers, such as urethanes and epoxies. The polymers are melted, partially cross-linked prior to the depositing, deposited to form a component object, solidified, and fully cross-linked. These polymers form networks of chemical bonds that span the deposited layers. Application of a directional electromagnetic field can be applied to aromatic polymers after deposition to align the polymers for improved bonding between the deposited layers.

  17. Antibody recognition of Z-DNA

    International Nuclear Information System (INIS)

    Lafer, E.M.; Moeller, A.; Valle, R.P.C.; Nordheim, V.A.; Rich, A.; Stollar, B.D.; Massachusetts Inst. of Tech., Cambridge)

    1983-01-01

    To measure serological reactions under physiological ionic strength, we prepared a brominated (Bl) poly(dG-dC).poly(dG-dC), which forms a stable Z helix in solutions of low salt concentration. Mice and rabbits were immunized with this polymer complexed with the basic protein methylated bovine serum albumin (MBSA), and it was discovered that the Z-DNA helix is a strong immunogen. Various antibody populations were purified from the rabbit serum by quantitative immunoprecipitation. Spleen cells from the mice were used for the preparation of hybridoma cell lines secreting monoclonal antibodies. Anti-Z-DNA antibodies were also raised by immunizing animals with poly(dG-dm 5 C).poly(dG-dm 5 C) under conditions where it was reported to be in the left-handed Z conformation as well as unmodified poly(dG-dC).poly(dG-dC) that was in the right-handed B conformation: both were complexed with MBSA. Z-DNA reactive antibodies were found in both murine and human SLE. A Z-DNA-specific as well as a dDNA and Z-DNA cross-reactive antibody population were distinguished by affinity chromatography of the SLE sera. The specificities of the various anti-Z-DNA antibody populations were measured by direct-binding and competitive radioimmunoassays, using synthetic polymers of defined structure under various ionic strengths. These studies allow us to map the possible antigenic sites for these antibodies, which serve as a model for DNA-protein recognition. The findings also established the usefulness of the antibodies as biochemical probes for Z-DNA. 29 references, 6 figures, 1 table

  18. Radiation treated propylene polymers

    International Nuclear Information System (INIS)

    Hoffman, W.A. III; Baum, G.A.

    1982-01-01

    A method is provided for imparting improved strength and discoloration resistance to a stabilized propylene polymer that is to be exposed to a sterilizing dose of radiation. From 200 to 400 ppm of a phenolic antioxidant containing an isocyanurate group in its molecular structure, and a thiosynergist in an amount at least 6 times the weight of the antioxidant, are incorporated into the polymer before irradiation

  19. Interfaced conducting polymers

    Czech Academy of Sciences Publication Activity Database

    Stejskal, Jaroslav; Bober, Patrycja; Trchová, Miroslava; Nuzhnyy, Dmitry; Bovtun, Viktor; Savinov, Maxim; Petzelt, Jan; Prokeš, J.

    2017-01-01

    Roč. 224, February (2017), s. 109-115 ISSN 0379-6779 R&D Projects: GA ČR(CZ) GA16-02787S Institutional support: RVO:61389013 ; RVO:68378271 Keywords : polyaniline * polypyrrole * poly(p-phenylenediamine) Subject RIV: CD - Macromolecular Chemistry; CD - Macromolecular Chemistry (FZU-D) OBOR OECD: Polymer science; Polymer science (FZU-D) Impact factor: 2.435, year: 2016

  20. Sulfur polymer cement concrete

    International Nuclear Information System (INIS)

    Weber, H.H.; McBee, W.C.

    1990-01-01

    Sulfur-based composite materials formulated using sulfur polymer cement (SPC) and mineral aggregates are described and compared with conventional portland cement based materials. Materials characteristics presented include mechanical strength, chemical resistance, impact resistance, moisture permeation, and linear shrinkage during placement and curing. Examples of preparation and placement of sulfur polymer cement concrete (SC) are described using commercial scale equipment. SC applications presented are focused into hostile chemical environments where severe portland cement concrete (PCC) failure has occurred

  1. Radiation chemistry of polymers

    International Nuclear Information System (INIS)

    Charlesby, A.

    1987-01-01

    There are several and quite distinct major fields of interest discussed in this paper. The first deals with the modification of existing polymers either by main-chain scission or by cross-linking; the theories of these patterns of behavior are summarized here, and typical examples of polymers that show these alternative reactions are given. These are not comprehensive to avoid this presentation becoming a catalog of similar patterns of behavior

  2. Rapid Polymer Sequencer

    Science.gov (United States)

    Stolc, Viktor (Inventor); Brock, Matthew W (Inventor)

    2013-01-01

    Method and system for rapid and accurate determination of each of a sequence of unknown polymer components, such as nucleic acid components. A self-assembling monolayer of a selected substance is optionally provided on an interior surface of a pipette tip, and the interior surface is immersed in a selected liquid. A selected electrical field is impressed in a longitudinal direction, or in a transverse direction, in the tip region, a polymer sequence is passed through the tip region, and a change in an electrical current signal is measured as each polymer component passes through the tip region. Each of the measured changes in electrical current signals is compared with a database of reference electrical change signals, with each reference signal corresponding to an identified polymer component, to identify the unknown polymer component with a reference polymer component. The nanopore preferably has a pore inner diameter of no more than about 40 nm and is prepared by heating and pulling a very small section of a glass tubing.

  3. DNA Vaccines

    Indian Academy of Sciences (India)

    diseases. Keywords. DNA vaccine, immune response, antibodies, infectious diseases. GENERAL .... tein vaccines require expensive virus/protein purification tech- niques as ... sphere continue to remain major health hazards in developing nations. ... significance since it can be produced at a very low cost and can be stored ...

  4. DNA Investigations.

    Science.gov (United States)

    Mayo, Ellen S.; Bertino, Anthony J.

    1991-01-01

    Presents a simulation activity that allow students to work through the exercise of DNA profiling and to grapple with some analytical and ethical questions involving a couple arranging with a surrogate mother to have a baby. Can be used to teach the principles of restriction enzyme digestion, gel electrophoresis, and probe hybridization. (MDH)

  5. Rate in template-directed polymer synthesis.

    Science.gov (United States)

    Saito, Takuya

    2014-06-01

    We discuss the temporal efficiency of template-directed polymer synthesis, such as DNA replication and transcription, under a given template string. To weigh the synthesis speed and accuracy on the same scale, we propose a template-directed synthesis (TDS) rate, which contains an expression analogous to that for the Shannon entropy. Increasing the synthesis speed accelerates the TDS rate, but the TDS rate is lowered if the produced sequences are diversified. We apply the TDS rate to some production system models and investigate how the balance between the speed and the accuracy is affected by changes in the system conditions.

  6. A Hard Constraint Algorithm to Model Particle Interactions in DNA-laden Flows

    Energy Technology Data Exchange (ETDEWEB)

    Trebotich, D; Miller, G H; Bybee, M D

    2006-08-01

    We present a new method for particle interactions in polymer models of DNA. The DNA is represented by a bead-rod polymer model and is fully-coupled to the fluid. The main objective in this work is to implement short-range forces to properly model polymer-polymer and polymer-surface interactions, specifically, rod-rod and rod-surface uncrossing. Our new method is based on a rigid constraint algorithm whereby rods elastically bounce off one another to prevent crossing, similar to our previous algorithm used to model polymer-surface interactions. We compare this model to a classical (smooth) potential which acts as a repulsive force between rods, and rods and surfaces.

  7. Precursor polymer compositions comprising polybenzimidazole

    Science.gov (United States)

    Klaehn, John R.; Peterson, Eric S.; Orme, Christopher J.

    2015-07-14

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  8. DNA repair

    International Nuclear Information System (INIS)

    Setlow, R.

    1978-01-01

    Some topics discussed are as follows: difficulty in extrapolating data from E. coli to mammalian systems; mutations caused by UV-induced changes in DNA; mutants deficient in excision repair; other postreplication mechanisms; kinds of excision repair systems; detection of repair by biochemical or biophysical means; human mutants deficient in repair; mutagenic effects of UV on XP cells; and detection of UV-repair defects among XP individuals

  9. Towards DNA-Based Programmable Matter

    Science.gov (United States)

    2012-02-28

    thiolated   ssDNA  was  first  immobilized  onto  the  gold...surface.  The  surface  was  then  passivated  with   mercaptohexanol.  Subsequently,  another  complementary   thiolated ...right).       Approach  3:  DNA-­‐mediated  interaction  between   polymer -­‐coated  surfaces   We  also  tried

  10. Polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Baldock, C [Institute of Medical Physics, School of Physics, University of Sydney (Australia); De Deene, Y [Radiotherapy and Nuclear Medicine, Ghent University Hospital (Belgium); Doran, S [CRUK Clinical Magnetic Resonance Research Group, Institute of Cancer Research, Surrey (United Kingdom); Ibbott, G [Radiation Physics, UT M D Anderson Cancer Center, Houston, TX (United States); Jirasek, A [Department of Physics and Astronomy, University of Victoria, Victoria, BC (Canada); Lepage, M [Centre d' imagerie moleculaire de Sherbrooke, Departement de medecine nucleaire et de radiobiologie, Universite de Sherbrooke, Sherbrooke, QC (Canada); McAuley, K B [Department of Chemical Engineering, Queen' s University, Kingston, ON (Canada); Oldham, M [Department of Radiation Oncology, Duke University Medical Center, Durham, NC (United States); Schreiner, L J [Cancer Centre of South Eastern Ontario, Kingston, ON (Canada)], E-mail: c.baldock@physics.usyd.edu.au, E-mail: yves.dedeene@ugent.be

    2010-03-07

    Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented. (topical review)

  11. Supercritical transitiometry of polymers.

    Science.gov (United States)

    Randzio, S L; Grolier, J P

    1998-06-01

    Employing supercritical fluids (SCFs) during polymers processing allows the unusual properties of SCFs to be exploited for making polymer products that cannot be obtained by other means. A new supercritical transitiometer has been constructed to permit study of the interactions of SCFs with polymers during processing under well-defined conditions of temperature and pressure. The supercritical transitiometer allows pressure to be exerted by either a supercritical fluid or a neutral medium and enables simultaneous determination of four basic parameters of a transition, i.e., p, T, Δ(tr)H and Δ(tr)V. This permits determination of the SCF effect on modification of the polymer structure at a given pressure and temperature and defines conditions to allow reproducible preparation of new polymer structures. Study of a semicrystalline polyethylene by this method has defined conditions for preparation of new microfoamed phases with good mechanical properties. The low densities and microporous structures of the new materials may make them useful for applications in medicine, pharmacy, or the food industry, for example.

  12. Multifunctional Polymer Nanocomposites

    Science.gov (United States)

    Galaska, Alexandra Maria; Song, Haixiang; Guo, Zhanhu

    With more awareness of energy conversion/storage and saving, different strategies have been developed to utilize the sustainable and renewable energy. Introducing nanoscale fillers can make inert polymer matrix possess unique properties to satisfy certain functions. For example, alumina nanoparticles have strengthened the weak thermosetting polymers. A combined mixture of carbon nanofibers and magnetite nanoparticles have made the inert epoxy sensitive for magnetic field for sensing applications. Introducing silica nanoparticles into conductive polymers such as polyaniline has enhanced the giant magnetoresistance behaviors. The introduced nanoparticles have made the transparent polymer have the electromagnetic interference (EMI) shielding function while reduce the density significantly. With the desired miniaturization, the materials combining different functionalities have become importantly interesting. In this talk, methodologies to prepare nanocomposites and their effects on the produced nanocomposites will be discussed. A variety of advanced polymer nanocomposites will be introduced. Unique properties including mechanical, electrical, magnetoresistance etc. and the applications for environmental remediation, energy storage/saving, fire retardancy, electromagnetic interference shielding, and electronic devices will be presented.

  13. Synthesis of DNA block copolymers with extended nucleic acid segments by enzymatic ligation : cut and paste large hybrid architectures

    NARCIS (Netherlands)

    Ayaz, Meryem S.; Kwak, Minseok; Alemdaroglu, Fikri E.; Wang, Jie; Berger, Ruediger; Herrmann, Andreas; Berger, Rüdiger

    2011-01-01

    Ultra-high molecular weight DNA/polymer hybrid materials were prepared employing molecular biology techniques. Nucleic acid restriction and ligation enzymes were used to generate linear DNA di- and triblock copolymers that contain up to thousands of base pairs in the DNA segments.

  14. Effect of introduction of chondroitin sulfate into polymer-peptide conjugate responding to intracellular signals

    Science.gov (United States)

    Tomiyama, Tetsuro; Toita, Riki; Kang, Jeong-Hun; Koga, Haruka; Shiosaki, Shujiro; Mori, Takeshi; Niidome, Takuro; Katayama, Yoshiki

    2011-09-01

    We recently developed a novel tumor-targeted gene delivery system responding to hyperactivated intracellular signals. Polymeric carrier for gene delivery consists of hydrophilic neutral polymer as main chains and cationic peptide substrate for target enzyme as side chains, and was named polymer-peptide conjugate (PPC). Introduction of chondroitin sulfate (CS), which induces receptor-medicated endocytosis, into polymers mainly with a high cationic charge density such as polyethylenimine can increase tumor-targeted gene delivery. In the present study, we examined whether introduction of CS into PPC containing five cationic amino acids can increase gene expression in tumor cells. Size and zeta potential of plasmid DNA (pDNA)/PPC/CS complex were <200 nm and between -10 and -15 mV, respectively. In tumor cell experiments, pDNA/PPC/CS complex showed lower stability and gene regulation, compared with that of pDNA/PPC. Moreover, no difference in gene expression was identified between positive and negative polymer. These results were caused by fast disintegration of pDNA/PPC/CS complexes in the presence of serum. Thus, we suggest that introduction of negatively charged CS into polymers with a low charge density may lead to low stability and gene regulation of complexes.

  15. Design of polymer motifs for nucleic acid recognition and assembly stabilization

    Science.gov (United States)

    Zhou, Zhun

    This dissertation describes the synthesis and assembly of bio-functional polymers and the applications of these polymers to drug encapsulation, delivery, and multivalent biomimetic macromolecular recognition between synthetic polymer and nucleic acids. The main content is divided into three parts: (1) polyacidic domains as strongly stabilizing design elements for aqueous phase polyacrylate diblock assembly; (2) small molecule/polymer recognition triggered macromolecular assembly and drug encapsulation; (3) trizaine derivatized polymer as a novel class of "bifacial polymer nucleic acid" (bPoNA) and applications of bPoNA to nanoparticle loading of DNA/RNA, silencing delivery as well as control of aptamer function. Through the studies in part (1) and part (2), it was demonstrated that well-designed polymer motifs are not only able to enhance assemblies driven by non-specific hydrophobic effect, but are also able to direct assemblies based on specific recognitions. In part (3) of this dissertation, this concept was further extended by the design of polyacrylate polymers that are capable of discrete and robust hybridization with nucleic acids. This surprising finding demonstrated both fundamental and practical applications. Overall, these studies provided insights into the rational design elements for improving the bio-functions of synthetic polymers, and significantly expanded the scope of biological applications in which polymers synthesized via controlled radical polymerization may play a role.

  16. Flame spraying of polymers

    International Nuclear Information System (INIS)

    Varacalle, D.J. Jr.; Zeek, D.P.; Couch, K.W.; Benson, D.M.; Kirk, S.M.

    1997-01-01

    Statistical design-of-experiment studies of the thermal spraying of polymer powders are presented. Studies of the subsonic combustion (i.e., Flame) process were conducted in order to determine the quality and economics of polyester and urethane coatings. Thermally sprayed polymer coatings are of interest to several industries for anticorrosion applications, including the chemical, automotive, and aircraft industries. In this study, the coating design has been optimized for a site-specific application using Taguchi-type fractional-factorial experiments. Optimized coating designs are presented for the two powder systems. A substantial range of thermal processing conditions and their effect on the resultant polymer coatings is presented. The coatings were characterized by optical metallography, hardness testing, tensile testing, and compositional analysis. Characterization of the coatings yielded the thickness, bond strength, Knoop microhardness, roughness, deposition efficiency, and porosity. Confirmation testing was accomplished to verify the coating designs

  17. Nanostructured silicate polymer concrete

    Directory of Open Access Journals (Sweden)

    Figovskiy Oleg L'vovich

    2014-03-01

    Full Text Available It has been known that acid-resistant concretes on the liquid glass basis have high porosity (up to 18~20 %, low strength and insufficient water resistance. Significant increasing of silicate matrix strength and density was carried out by incorporation of special liquid organic alkali-soluble silicate additives, which block superficial pores and reduce concrete shrinkage deformation. It was demonstrated that introduction of tetrafurfuryloxisilane additive sharply increases strength, durability and shock resistance of silicate polymer concrete in aggressive media. The experiments showed, that the strength and density of silicate polymer concrete increase in case of decreasing liquid glass content. The authors obtained optimal content of silicate polymer concrete, which possesses increased strength, durability, density and crack-resistance. Diffusive permeability of concrete and its chemical resistance has been investigated in various corroding media.

  18. Semi-metallic polymers

    DEFF Research Database (Denmark)

    Bubnova, Olga; Khan, Zia Ullah; Wang, Hui

    2014-01-01

    Polymers are lightweight, flexible, solution-processable materials that are promising for low-cost printed electronics as well as for mass-produced and large-area applications. Previous studies demonstrated that they can possess insulating, semiconducting or metallic properties; here we report...... that polymers can also be semi-metallic. Semi-metals, exemplified by bismuth, graphite and telluride alloys, have no energy bandgap and a very low density of states at the Fermi level. Furthermore, they typically have a higher Seebeck coefficient and lower thermal conductivities compared with metals, thus being...... a Fermi glass to a semi-metal. The high Seebeck value, the metallic conductivity at room temperature and the absence of unpaired electron spins makes polymer semi-metals attractive for thermoelectrics and spintronics....

  19. 'Stuffed' conducting polymers

    DEFF Research Database (Denmark)

    Winther-Jensen, Bjørn; Chen, Jun; West, Keld

    2005-01-01

    Conducting polymers (CP) obtained by oxidative polymerization using iron(III) salts shrink when Fe(II) and the excess counter ions are washed out after polymerization. This phenomenon can be used to incorporate active molecules into the CP matrix via their addition to the wash liquid. In the pres......Conducting polymers (CP) obtained by oxidative polymerization using iron(III) salts shrink when Fe(II) and the excess counter ions are washed out after polymerization. This phenomenon can be used to incorporate active molecules into the CP matrix via their addition to the wash liquid....... In the present work we demonstrate this principle on three different CP's: polypyrrole (PPy), poly-terthiophene (PTTh) and poly(3,4-ethylenedioxy thiophene) (PEDT), using ferrocene as a model molecule to be trapped in the polymer films. (c) 2005 Elsevier Ltd. All rights reserved....

  20. Exploring the role of peptides in polymer-based gene delivery.

    Science.gov (United States)

    Sun, Yanping; Yang, Zhen; Wang, Chunxi; Yang, Tianzhi; Cai, Cuifang; Zhao, Xiaoyun; Yang, Li; Ding, Pingtian

    2017-09-15

    Polymers are widely studied as non-viral gene vectors because of their strong DNA binding ability, capacity to carry large payload, flexibility of chemical modifications, low immunogenicity, and facile processes for manufacturing. However, high cytotoxicity and low transfection efficiency substantially restrict their application in clinical trials. Incorporating functional peptides is a promising approach to address these issues. Peptides demonstrate various functions in polymer-based gene delivery systems, such as targeting to specific cells, breaching membrane barriers, facilitating DNA condensation and release, and lowering cytotoxicity. In this review, we systematically summarize the role of peptides in polymer-based gene delivery, and elaborate how to rationally design polymer-peptide based gene delivery vectors. Polymers are widely studied as non-viral gene vectors, but suffer from high cytotoxicity and low transfection efficiency. Incorporating short, bioactive peptides into polymer-based gene delivery systems can address this issue. Peptides demonstrate various functions in polymer-based gene delivery systems, such as targeting to specific cells, breaching membrane barriers, facilitating DNA condensation and release, and lowering cytotoxicity. In this review, we highlight the peptides' roles in polymer-based gene delivery, and elaborate how to utilize various functional peptides to enhance the transfection efficiency of polymers. The optimized peptide-polymer vectors should be able to alter their structures and functions according to biological microenvironments and utilize inherent intracellular pathways of cells, and consequently overcome the barriers during gene delivery to enhance transfection efficiency. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. Electric field induced dewetting at polymer/polymer interfaces

    NARCIS (Netherlands)

    Lin, Z.Q.; Kerle, T.; Russell, T.P.; Schäffer, E.; Steiner, U

    2002-01-01

    External electric fields were used to amplify interfacial fluctuations in the air/polymer/polymer system where one polymer dewets the other. Two different hydrodynamic regimes were found as a function of electric field strength. If heterogeneous nucleation leads to the formation of holes before the

  2. Polymer containing functional end groups is base for new polymers

    Science.gov (United States)

    Hirshfield, S. M.

    1971-01-01

    Butadiene is polymerized with lithium-p-lithiophenoxide to produce linear polymer containing oxy-lithium group at one end and active carbon-lithium group at other end. Living polymers represent new approach to preparation of difunctional polymers in which structural features, molecular weight, type and number of end groups are controlled.

  3. Force-extension behavior of DNA in the presence of DNA-bending nucleoid associated proteins

    Science.gov (United States)

    Dahlke, K.; Sing, C. E.

    2018-02-01

    Interactions between nucleoid associated proteins (NAPs) and DNA affect DNA polymer conformation, leading to phenomena such as concentration dependent force-extension behavior. These effects, in turn, also impact the local binding behavior of the protein, such as high forces causing proteins to unbind, or proteins binding favorably to locally bent DNA. We develop a coarse-grained NAP-DNA simulation model that incorporates both force- and concentration-dependent behaviors, in order to study the interplay between NAP binding and DNA conformation. This model system includes multi-state protein binding and unbinding, motivated by prior work, but is now dependent on the local structure of the DNA, which is related to external forces acting on the DNA strand. We observe the expected qualitative binding behavior, where more proteins are bound at lower forces than at higher forces. Our model also includes NAP-induced DNA bending, which affects DNA elasticity. We see semi-quantitative matching of our simulated force-extension behavior to the reported experimental data. By using a coarse-grained simulation, we are also able to look at non-equilibrium behaviors, such as dynamic extension of a DNA strand. We stretch a DNA strand at different rates and at different NAP concentrations to observe how the time scales of the system (such as pulling time and unbinding time) work in concert. When these time scales are similar, we observe measurable rate-dependent changes in the system, which include the number of proteins bound and the force required to extend the DNA molecule. This suggests that the relative time scales of different dynamic processes play an important role in the behavior of NAP-DNA systems.

  4. Raw and renewable polymers

    CSIR Research Space (South Africa)

    Joseph, S

    2010-01-01

    Full Text Available in the permeability of the membrane and HO H3C H3C H2C H2C HO OH NH NH OH O OC C n O O O O Fig. 4 Structure of Chitin Raw and Renewable Polymers promoting internal osmotic imbalances. This results in leaching of electrolytes and proteins. 2... is often lost. In most cases this denaturation is not reversible. R-CH-COOH NH2 w Amino acid H2N COOHR a Amino acid Fig. 5 Structure of amino acid Raw and Renewable Polymers The solubilities of proteins vary considerably based on compositions...

  5. Delocalization in polymer models

    CERN Document Server

    Jitomirskaya, S Yu; Stolz, G

    2003-01-01

    A polymer model is a one-dimensional Schroedinger operator composed of two finite building blocks. If the two associated transfer matrices commute, the corresponding energy is called critical. Such critical energies appear in physical models, an example being the widely studied random dimer model. Although the random models are known to have pure-point spectrum with exponentially localized eigenstates for almost every configuration of the polymers, the spreading of an initially localized wave packet is here proven to be at least diffusive for every configuration.

  6. Nanoparticles from Renewable Polymers

    Directory of Open Access Journals (Sweden)

    Frederik Roman Wurm

    2014-07-01

    Full Text Available The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights polysaccharides, polyesters, lignin or by complex structure (proteins, lignin. This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications.

  7. Polymers at cryogenic temperatures

    CERN Document Server

    Fu, Shao-Yun

    2013-01-01

    Kalia and Fu's novel monograph covers cryogenic treatment, properties and applications of cryo-treated polymer materials. Written by numerous international experts, the twelve chapters in this book offer the reader a comprehensive picture of the latest findings and developments, as well as an outlook on the field. Cryogenic technology has seen remarkable progress in the past few years and especially cryogenic properties of polymers are attracting attention through new breakthroughs in space, superconducting, magnetic and electronic techniques. This book is a valuable resource for researchers, educators, engineers and graduate students in the field and at technical institutions.

  8. Polymers and colloids

    International Nuclear Information System (INIS)

    Schurtenberger, P.

    1996-01-01

    A wealth of structural information from colloid and polymer solutions on a large range of length scales can be obtained using small angle neutron scattering (SANS) experiments. After a general introduction to the field of soft condensed matter, I shall give a few selected examples on how SANS combined with suitable contrast variation schemes can be used to extract information on the size and conformation of polymer coils in solution and in the melt, and on the local structure and flexibility of polymerlike micelles and microemulsions. (author) 8 figs., tabs., 44 refs

  9. Polymers and colloids

    Energy Technology Data Exchange (ETDEWEB)

    Schurtenberger, P [ETH Zurich, Inst. fuer Polymere, Zurich (Switzerland)

    1996-11-01

    A wealth of structural information from colloid and polymer solutions on a large range of length scales can be obtained using small angle neutron scattering (SANS) experiments. After a general introduction to the field of soft condensed matter, I shall give a few selected examples on how SANS combined with suitable contrast variation schemes can be used to extract information on the size and conformation of polymer coils in solution and in the melt, and on the local structure and flexibility of polymerlike micelles and microemulsions. (author) 8 figs., tabs., 44 refs.

  10. Ballistic nanoindentation of polymers

    Science.gov (United States)

    Gotsmann, B.; Rothuizen, H.; Duerig, U.

    2008-09-01

    Indentation of a sharp (20 nm) cantilevered silicon tip into a polymer (SU8) surface is analyzed experimentally and through finite-element simulations. A rate effect on the microsecond scale that eases indentation is found, in contrast to the commonly observed hardening at high strain rates. The observed rate effect is discussed in terms of adiabatic heating and inertial force overshoot. The estimated magnitude of adiabatic heating is marginal, but the force overshoot itself is large enough to explain the data. The data imply that topographic patterning of a polymer at megahertz rates is feasible.

  11. Mechanically Invisible Polymer Coatings

    DEFF Research Database (Denmark)

    2014-01-01

    phase comprises particles, said particles comprising a filler material and an encapsulating coating of a second polymeric material, wherein the backbones of the first and second polymeric materials are the same. The composition may be used in electroactive polymers (EAPs) in order to obtain mechanically......The present invention relates to a composition comprising encapsulated particles in a polymeric material. The composition comprises a continuous phase and a discontinuous phase incorporated therein, wherein the continuous phase comprises a first polymeric material and wherein the discontinuous...... invisible polymer coatings....

  12. Antibacterial polymer coatings.

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Mollye C.; Allen, Ashley N.; Barnhart, Meghan; Tucker, Mark David; Hibbs, Michael R.

    2009-09-01

    A series of poly(sulfone)s with quaternary ammonium groups and another series with aldehyde groups are synthesized and tested for biocidal activity against vegetative bacteria and spores, respectively. The polymers are sprayed onto substrates as coatings which are then exposed to aqueous suspensions of organisms. The coatings are inherently biocidal and do not release any agents into the environment. The coatings adhere well to both glass and CARC-coated coupons and they exhibit significant biotoxicity. The most effective quaternary ammonium polymers kills 99.9% of both gram negative and gram positive bacteria and the best aldehyde coating kills 81% of the spores on its surface.

  13. Polymer architecture and drug delivery.

    Science.gov (United States)

    Qiu, Li Yan; Bae, You Han

    2006-01-01

    Polymers occupy a major portion of materials used for controlled release formulations and drug-targeting systems because this class of materials presents seemingly endless diversity in topology and chemistry. This is a crucial advantage over other classes of materials to meet the ever-increasing requirements of new designs of drug delivery formulations. The polymer architecture (topology) describes the shape of a single polymer molecule. Every natural, seminatural, and synthetic polymer falls into one of categorized architectures: linear, graft, branched, cross-linked, block, star-shaped, and dendron/dendrimer topology. Although this topic spans a truly broad area in polymer science, this review introduces polymer architectures along with brief synthetic approaches for pharmaceutical scientists who are not familiar with polymer science, summarizes the characteristic properties of each architecture useful for drug delivery applications, and covers recent advances in drug delivery relevant to polymer architecture.

  14. Statics and dynamics of DNA knotting

    Science.gov (United States)

    Orlandini, Enzo

    2018-02-01

    Knots and entanglement in polymers and biopolymers such as DNA and proteins constitute a timely topic that spans various scientific disciplines ranging from physics to chemistry, biology and mathematics. Although in the past many advancements have been made in understanding the equilibrium knotting probability and knot complexity of long polymer chains in solutions, many questions have been addressed in recent years by both experimental and theoretical means—for instance, how the knotting probability depends on the quality of the solvent, the elastic properties of the molecule and its degree of confinement. How knots form, evolve and eventually disappear in a fluctuating chain. Are the equilibrium and non-equilibrium properties of knotted molecules affected by the knot swelling/shrinking dynamics? Moreover, thanks to the great advance in nanotechnology and micromanipulation techniques, nowadays knots can be ‘manually’ tied in a single DNA molecule, followed during their motion along the chains, forced to pass through nanopores, or stretched by external forces or elongational flows. All these experimental approaches allow access to new information on the interplay of topology and polymer physics, and this has opened new perspectives in the field. Here, we provide an overview of the current knowledge of this topic, stressing the main results obtained, including the recent developments in experimental and computational approaches. Since almost all experiments on knotting involve DNA, the review will be mainly focused on the topological properties of this fascinating and biologically relevant molecule.

  15. Conducting polymer 3D microelectrodes

    DEFF Research Database (Denmark)

    Sasso, Luigi; Vazquez, Patricia; Vedarethinam, Indumathi

    2010-01-01

    Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained...... showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared...

  16. Shape memory polymer medical device

    Science.gov (United States)

    Maitland, Duncan [Pleasant Hill, CA; Benett, William J [Livermore, CA; Bearinger, Jane P [Livermore, CA; Wilson, Thomas S [San Leandro, CA; Small, IV, Ward; Schumann, Daniel L [Concord, CA; Jensen, Wayne A [Livermore, CA; Ortega, Jason M [Pacifica, CA; Marion, III, John E.; Loge, Jeffrey M [Stockton, CA

    2010-06-29

    A system for removing matter from a conduit. The system includes the steps of passing a transport vehicle and a shape memory polymer material through the conduit, transmitting energy to the shape memory polymer material for moving the shape memory polymer material from a first shape to a second and different shape, and withdrawing the transport vehicle and the shape memory polymer material through the conduit carrying the matter.

  17. DNA repair

    International Nuclear Information System (INIS)

    Van Zeeland, A.A.

    1984-01-01

    In this chapter a series of DNA repair pathways are discussed which are available to the cell to cope with the problem of DNA damaged by chemical or physical agents. In the case of microorganisms our knowledge about the precise mechanism of each DNA repair pathway and the regulation of it has been improved considerably when mutants deficient in these repair mechanisms became available. In the case of mammalian cells in culture, until recently there were very little repair deficient mutants available, because in almost all mammalian cells in culture at least the diploid number of chromosomes is present. Therefore the frequency of repair deficient mutants in such populations is very low. Nevertheless because replica plating techniques are improving some mutants from Chinese hamsters ovary cells and L5178Y mouse lymphoma cells are now available. In the case of human cells, cultures obtained from patients with certain genetic diseases are available. A number of cells appear to be sensitive to some chemical or physical mutagens. These include cells from patients suffering from xeroderma pigmentosum, Ataxia telangiectasia, Fanconi's anemia, Cockayne's syndrome. However, only in the case of xeroderma pigmentosum cells, has the sensitivity to ultraviolet light been clearly correlated with a deficiency in excision repair of pyrimidine dimers. Furthermore the work with strains obtained from biopsies from man is difficult because these cells generally have low cloning efficiencies and also have a limited lifespan in vitro. It is therefore very important that more repair deficient mutants will become available from established cell lines from human or animal origin

  18. Frictional properties of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N; Persson, Bo N J

    2008-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively i...

  19. New polymers for phase partitioning

    Science.gov (United States)

    Harris, J. M.

    1981-01-01

    The synthesizing of several polyethylene glycols having crown ethers attached is reported. This work led to the identification of three new polymer types which promise to be more effective at selectively binding specific cell types. Work was completed on identification of chemical properties of the new polymer crowns and on development of new techniques for determination of polymer-phase composition.

  20. Nonlinear microstructured polymer optical fibres

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch

    is potentially the case for microstructured polymer optical fibres (mPOFs). Another advantage is that polymer materials have a higher biocompatibility than silica, meaning that it is easier to bond certain types of biosensor materials to a polymer surface than to silica. As with silica PCFs, it is difficult...

  1. Reversible networks in supramolecular polymers

    NARCIS (Netherlands)

    Havermans - van Beek, D.J.M.

    2007-01-01

    Non–covalent interactions between low molecular weight polymers form the basis of supramolecular polymers. The material properties of such polymers are determined by the strength and lifetime of the non–covalent reversible interactions. Due to the reversibility of the interactions between the low

  2. White polymer light-emitting diode based on polymer blending

    International Nuclear Information System (INIS)

    Lee, Yong Kyun; Kwon, Soon Kab; Kim, Jun Young; Park, Tae Jin; Song, Dae Ho; Kwon, Jang Hyuk; Choo, Dong Jun; Jang, Jin; Jin, Jae Kyu; You, Hong

    2006-01-01

    A series of white polymer light emitting devices have been fabricated by using a polymer blending system of polyfluorene-based blue and MEH-PPV red polymers. A device structure of ITO/PEDOT:PSS/polymer/LiF/Al was employed. The white polymer device exhibited a current efficiency of 4.33 cd/A (4,816 cd/m 2 , Q.E. = 1.9 %) and a maximum luminance of 21,430 cd/m 2 at 9.2 V. The CIE coordinates were (0.35, 0.37) at 5 V and (0.29, 0.30) at 9 V.

  3. Polymers of phenylenediamines

    Czech Academy of Sciences Publication Activity Database

    Stejskal, Jaroslav

    2015-01-01

    Roč. 41, February (2015), s. 1-31 ISSN 0079-6700 R&D Projects: GA ČR(CZ) GA13-00270S Institutional support: RVO:61389013 Keywords : polyphenylenediamine * phenylenediamine * conducting polymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 27.184, year: 2015

  4. Nanoporous thermosetting polymers.

    Science.gov (United States)

    Raman, Vijay I; Palmese, Giuseppe R

    2005-02-15

    Potential applications of nanoporous thermosetting polymers include polyelectrolytes in fuel cells, separation membranes, adsorption media, and sensors. Design of nanoporous polymers for such applications entails controlling permeability by tailoring pore size, structure, and interface chemistry. Nanoporous thermosetting polymers are often synthesized via free radical mechanisms using solvents that phase separate during polymerization. In this work, a novel technique for the synthesis of nanoporous thermosets is presented that is based on the reactive encapsulation of an inert solvent using step-growth cross-linking polymerization without micro/macroscopic phase separation. The criteria for selecting such a monomer-polymer-solvent system are discussed based on FTIR analysis, observed micro/macroscopic phase separation, and thermodynamics of swelling. Investigation of resulting network pore structures by scanning electron microscopy (SEM) and small-angle X-ray scattering following extraction and supercritical drying using carbon dioxide showed that nanoporous polymeric materials with pore sizes ranging from 1 to 50 nm can be synthesized by varying the solvent content. The differences in the porous morphology of these materials compared to more common free radically polymerized analogues that exhibit phase separation were evident from SEM imaging. Furthermore, it was demonstrated that the chemical activity of the nanoporous materials obtained by our method could be tailored by grafting appropriate functional groups at the pore interface.

  5. Characterization of healable polymers

    Science.gov (United States)

    Nielsen, C.; Weizman, Or; Nemat-Nasser, Sia

    2010-04-01

    Materials with an internal mechanism for damage repair would be valuable in isolated environments where access is difficult or impossible. Current work is focused on characterizing neat polymers with reformable cross-linking bonds. These bonds are thermally reversible, the result of a Diels-Alder cycloaddition between furan and maleimide monomers. Candidate polymers are examined using modulated differential scanning calorimetry (DSC) to confirm the presence of reversible bonding. One polymer, 2MEP3FT, was expected to have these bonds, but none were observed. A second polymer, 2MEP4FS, with a modified furan monomer does exhibit reversible bonding. Further DSC testing and dynamic mechanical thermal analyses (DMA) are conducted to determine material properties such as glass transition temperature, storage modulus and quality of the polymerization. Healing efficiency is established using the double cleavage drilled compression (DCDC) fracture test. A column of material with a central hole is subjected to axial compression, driving cracks up and down the sample. After unloading, the cracks are healed, and the sample is retested. Comparing the results gives a quantitative evaluation of healing.

  6. Knots in polymers

    Indian Academy of Sciences (India)

    Abstract. Knots and topological entanglements play an important role in the statistical mechanics of polymers. While topological entanglement is a global property, it is possible to study the size of a knotted region both numerically and analytically. It can be shown that long-range repulsive interactions, as well as entropy ...

  7. Polyester polymer concrete overlay.

    Science.gov (United States)

    2013-01-01

    Polyester polymer concrete (PPC) was used in a trial application on a section of pavement that suffers from extensive studded tire wear. The purpose of the trial section is to determine if PPC is a possible repair strategy for this type of pavement d...

  8. Conductive polymer composition

    NARCIS (Netherlands)

    2010-01-01

    The present invention relates to a process for the preparation of a conductive polymer composition comprising graphene and the articles obtained by this process. The process comprises the following steps: A) contacting graphite oxide in an aqueous medium with a water-soluble or dispersible

  9. BEAM applications to polymer materials

    International Nuclear Information System (INIS)

    Tagawa, Seiichi

    1994-01-01

    Recently papers about beam applications to polymers have been increasing rapidly both in the fundamental and applied fields. Fairly large number of papers have been published in the fundamental aspects of radiation effects of beam applications to polymers such as pulse radiolysis and high density electronic excitation effects. A number of papers have been published in the more applied aspects of beam applications to polymers such as radiation processing and curing. The present paper describes recent beam applications to polymers. 1. Radiation Effects on Polymers; Radiation effects on polymers have been studied for more than 40 years. Most of work on radiation effects on polymers has been carried out by using high energy photon (gamma-ray) and electron beams, since polymers are sensitive to any kinds of ionizing radiation. Even non-ionizing radiation such as ultraviolet and visible light excites electronic excited states of polymers and then photo-chemical reactions of polymers are induced from the electronic excited states. Studies on radiation effects of other ionizing radiation on polymers have not been so popular for a long time. Recently application of new radiation such as ion beams to polymers have been worthy of remark in fields of advanced science and technology, since new radiation beams induce different radiation effects from those induced by high energy gamma-rays and electrons. 2. Beam Applications of Polymers; Recent progress in beam applications to polymers such as radiation processing and curing, x-ray and electron beam microlithography, and applications of new beams such as ion beams to polymers has been reviewed. (author)

  10. Conducting Polymers for Neutron Detection

    International Nuclear Information System (INIS)

    Clare Kimblin; Kirk Miller; Bob Vogel; Bill Quam; Harry McHugh; Glen Anthony; Steve Jones; Mike Grover

    2007-01-01

    Conjugated polymers have emerged as an attractive technology for large-area electronic applications. As organic semiconductors, they can be used to make large-area arrays of diodes or transistors using fabrication techniques developed for polymer coatings, such as spraying and screen-printing. We have demonstrated both neutron and alpha detection using diodes made from conjugated polymers and have done preliminary work to integrate a boron carbide layer into the conventional polymer device structure to capture thermal neutrons. The polymer devices appear to be insensitive to gamma rays, due to their small physical thickness and low atomic number

  11. Gel polymer electrolytes for batteries

    Science.gov (United States)

    Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William

    2014-11-18

    Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.

  12. Enzymatic production of 'monoclonal stoichiometric' single-stranded DNA oligonucleotides.

    Science.gov (United States)

    Ducani, Cosimo; Kaul, Corinna; Moche, Martin; Shih, William M; Högberg, Björn

    2013-07-01

    Single-stranded oligonucleotides are important as research tools, as diagnostic probes, in gene therapy and in DNA nanotechnology. Oligonucleotides are typically produced via solid-phase synthesis, using polymer chemistries that are limited relative to what biological systems produce. The number of errors in synthetic DNA increases with oligonucleotide length, and the resulting diversity of sequences can be a problem. Here we present the 'monoclonal stoichiometric' (MOSIC) method for enzyme-mediated production of DNA oligonucleotides. We amplified oligonucleotides from clonal templates derived from single bacterial colonies and then digested cutter hairpins in the products, which released pools of oligonucleotides with precisely controlled relative stoichiometric ratios. We prepared 14-378-nucleotide MOSIC oligonucleotides either by in vitro rolling-circle amplification or by amplification of phagemid DNA in Escherichia coli. Analyses of the formation of a DNA crystal and folding of DNA nanostructures confirmed the scalability, purity and stoichiometry of the produced oligonucleotides.

  13. Synthesis and Evaluation of Tetramethylguanidinium-Polyethylenimine Polymers as Efficient Gene Delivery Vectors

    Directory of Open Access Journals (Sweden)

    Manohar Mahato

    2014-01-01

    Full Text Available Previously, we demonstrated that 6-(N,N,N′,N′-tetramethylguanidinium chloride-hexanoyl-polyethylenimine (THP polymers exhibited significantly enhanced transfection efficiency and cell viability. Here, in the present study, we have synthesized a series of N,N,N′,N′-tetramethylguanidinium-polyethylenimine (TP1-TP5 polymers via a single-step reaction involving peripheral primary amines of bPEI and varying amounts of 2-(1H-benzotriazol-1-yl-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU. These polymers were found to interact efficiently with negatively charged pDNA and formed stable complexes in the size range of ~240–450 nm. Acid-base titration profiles revealed improved buffering capacity of TP polymers as compared to bPEI. Transfection and cytotoxicity assays performed with TP/pDNA complexes on HEK293, CHO, and HeLa cells showed significantly higher transfection efficiency and cell viability with one of the complexes, TP2/pDNA complex, exhibited the highest transfection efficiency (~1.4–2.3-fold outcompeting native bPEI and the commercially available transfection reagent, Lipofectamine 2000. Compared to previously reported THP polymers, the transfection efficiency of TP/pDNA complexes was found to be lower, as examined by flow cytometry. These results highlight the importance of the hydrophobic C-6 linker in THP polymers in forming compact nanostructures with pDNA, which might lead to efficient uptake and internalization of the complexes; however, the projected TP polymers offer an advantage of their rapid and economical one-step synthesis.

  14. Synthesis and evaluation of tetramethylguanidinium-polyethylenimine polymers as efficient gene delivery vectors.

    Science.gov (United States)

    Mahato, Manohar; Yadav, Santosh; Kumar, Pradeep; Sharma, Ashwani Kumar

    2014-01-01

    Previously, we demonstrated that 6-(N,N,N',N'-tetramethylguanidinium chloride)-hexanoyl-polyethylenimine (THP) polymers exhibited significantly enhanced transfection efficiency and cell viability. Here, in the present study, we have synthesized a series of N,N,N',N'-tetramethylguanidinium-polyethylenimine (TP1-TP5) polymers via a single-step reaction involving peripheral primary amines of bPEI and varying amounts of 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU). These polymers were found to interact efficiently with negatively charged pDNA and formed stable complexes in the size range of ~240-450 nm. Acid-base titration profiles revealed improved buffering capacity of TP polymers as compared to bPEI. Transfection and cytotoxicity assays performed with TP/pDNA complexes on HEK293, CHO, and HeLa cells showed significantly higher transfection efficiency and cell viability with one of the complexes, TP2/pDNA complex, exhibited the highest transfection efficiency (~1.4-2.3-fold) outcompeting native bPEI and the commercially available transfection reagent, Lipofectamine 2000. Compared to previously reported THP polymers, the transfection efficiency of TP/pDNA complexes was found to be lower, as examined by flow cytometry. These results highlight the importance of the hydrophobic C-6 linker in THP polymers in forming compact nanostructures with pDNA, which might lead to efficient uptake and internalization of the complexes; however, the projected TP polymers offer an advantage of their rapid and economical one-step synthesis.

  15. POLYMER ELECTROLYTE MEMBRANE FUEL CELLS

    DEFF Research Database (Denmark)

    2001-01-01

    A method for preparing polybenzimidazole or polybenzimidazole blend membranes and fabricating gas diffusion electrodes and membrane-electrode assemblies is provided for a high temperature polymer electrolyte membrane fuel cell. Blend polymer electrolyte membranes based on PBI and various...... thermoplastic polymers for high temperature polymer electrolyte fuel cells have also been developed. Miscible blends are used for solution casting of polymer membranes (solid electrolytes). High conductivity and enhanced mechanical strength were obtained for the blend polymer solid electrolytes....... With the thermally resistant polymer, e.g., polybenzimidazole or a mixture of polybenzimidazole and other thermoplastics as binder, the carbon-supported noble metal catalyst is tape-cast onto a hydrophobic supporting substrate. When doped with an acid mixture, electrodes are assembled with an acid doped solid...

  16. Electroacoustic miniaturized DNA-biosensor.

    Science.gov (United States)

    Gamby, Jean; Lazerges, Mathieu; Pernelle, Christine; Perrot, Hubert; Girault, Hubert H; Tribollet, Bernard

    2007-11-01

    A micrometer-sized electroacoustic DNA-biosensor was developed. The device included a thin semi-crystalline polyethylene terephthalate (PET) dielectric layer with two Ag microband electrodes on one side and a DNA thiol-labeled monolayer adsorbed on a gold surface on the other. A resonance wave was observed at 29 MHz with a network analyzer, upon AC voltage application between the two Ag electrodes, corresponding to electromechanical coupling induced by molecular dipoles of the PET polymer chain in the dielectric layer. It was found that the device size and geometry were well adapted to detect DNA hybridization, by measuring the capacity of the resonance response evolution: hybridization induced polarization of the dielectric material that affected the electromechanical coupling established in the dielectric layer. The 0.2 mm(2) sensor sensitive area allows detection in small volumes and still has higher detection levels for bioanalytical applications, the non-contact configuration adopted avoids electric faradic reactions that may damage biosensor sensitive layers, and finally, PET is a costless raw material, easy to process and well adapted for large scale production. The well-balanced technological and economic advantages of this kind of device make it a good candidate for biochip integration.

  17. Depletion-induced instability in protein-DNA mixtures: Influence of protein charge and size

    NARCIS (Netherlands)

    Vries, de R.J.

    2006-01-01

    While there is abundant experimental and theoretical work on polymer-induced DNA condensation, it is still unclear whether globular proteins can condense linear DNA or not. We develop a simple analytical approximation for the depletion attraction between rodlike segments of semiflexible

  18. Design Concept of Dialyzer Biomaterials: How to Find Biocompatible Polymers Based on the Biointerfacial Water Structure.

    Science.gov (United States)

    Tanaka, Masaru

    2017-01-01

    Although various types of materials have been used widely in dialyzers, most biomaterials lack the desired functional properties to interface with blood and have not been engineered for optimum performance. Therefore, there is increasing demand to develop novel materials to address such problems in the dialysis arena. Numerous parameters of polymeric biomaterials can affect biocompatibility in a controlled manner. The mechanisms responsible for the biocompatibility of polymers at the molecular level have not been clearly demonstrated, although many theoretical and experimental efforts have been made to try and understand them. Moreover, water interactions have been recognized as fundamental for the blood response to contact with polymers. We have proposed the 'intermediate water' concept and hypothesized that intermediate water, which prevents the proteins and blood cells from directly contacting the polymer surface, or nonfreezing water on the polymer surface, plays an important role in the biocompatibility of polymers. This chapter provides an overview of the recent experimental progress of biocompatible polymers measured by thermal, spectroscopic, and surface force techniques. Additionally, it highlights recent developments in the use of biocompatible polymeric biomaterials for dialyzers and provides an overview of the progress made in the design of multifunctional biomedical polymers by controlling the biointerfacial water structure through precision polymer synthesis. Key Messages: Intermediate water was found only in hydrated biopolymers (proteins, polysaccharides, and nucleic acids, DNA and RNA) and hydrated biocompatible synthetic polymers. Intermediate water could be one of the main screening factors for the design of appropriate dialyzer materials. © 2017 S. Karger AG, Basel.

  19. Adsorption and flocculation by polymers and polymer mixtures.

    Science.gov (United States)

    Gregory, John; Barany, Sandor

    2011-11-14

    Polymers of various types are in widespread use as flocculants in several industries. In most cases, polymer adsorption is an essential prerequisite for flocculation and kinetic aspects are very important. The rates of polymer adsorption and of re-conformation (relaxation) of adsorbed chains are key factors that influence the performance of flocculants and their mode of action. Polyelectrolytes often tend to adopt a rather flat adsorbed configuration and in this state their action is mainly through charge effects, including 'electrostatic patch' attraction. When the relaxation rate is quite low, particle collisions may occur while the adsorbed chains are still in an extended state and flocculation by polymer bridging may occur. These effects are now well understood and supported by much experimental evidence. In recent years there has been considerable interest in the use of multi-component flocculants, especially dual-polymer systems. In the latter case, there can be significant advantages over the use of single polymers. Despite some complications, there is a broad understanding of the action of dual polymer systems. In many cases the sequence of addition of the polymers is important and the pre-adsorbed polymer can have two important effects: providing adsorption sites for the second polymer or causing a more extended adsorbed conformation as a result of 'site blocking'. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Structure and Dynamics of Polymer/Polymer grafted nanoparticle composite

    Science.gov (United States)

    Archer, Lynden

    Addition of nanoparticles to polymers is a well-practiced methodology for augmenting various properties of the polymer host, including mechanical strength, thermal stability, barrier properties, dimensional stability and wear resistance. Many of these property changes are known to arise from nanoparticle-induced modification of polymer structure and chain dynamics, which are strong functions of the dispersion state of the nanoparticles' and on their relative size (D) to polymer chain dimensions (e.g. Random coil radius Rg or entanglement mesh size a) . This talk will discuss polymer nanocomposites (PNCs) comprised of Polyethylene Glycol (PEG) tethered silica nanoparticles (SiO2-PEG) dispersed in polymers as model systems for investigating phase stability and dynamics of PNCs. On the basis of small-angle X-ray Scattering, it will be shown that favorable enthalpic interactions between particle-tethered chains and a polymer host provides an important mechanism for creating PNCs in which particle aggregation is avoided. The talk will report on polymer and particle scale dynamics in these materials and will show that grafted nanoparticles well dispersed in a polymer host strongly influence the host polymer relaxation dynamics on all timescales and the polymers in turn produce dramatic changes in the nature (from diffusive to hyperdiffusive) and speed of nano particle decorrelation dynamics at the polymer entanglement threshold. A local viscosity model capable of explaining these observations is discussed and the results compared with scaling theories for NP motions in polymers This material is based on work supported by the National Science Foundation Award Nos. DMR-1609125 and CBET-1512297.

  1. How do polymers degrade?

    Science.gov (United States)

    Lyu, Suping

    2011-03-01

    Materials derived from agricultural products such as cellulose, starch, polylactide, etc. are more sustainable and environmentally benign than those derived from petroleum. However, applications of these polymers are limited by their processing properties, chemical and thermal stabilities. For example, polyethylene terephthalate fabrics last for many years under normal use conditions, but polylactide fabrics cannot due to chemical degradation. There are two primary mechanisms through which these polymers degrade: via hydrolysis and via oxidation. Both of these two mechanisms are related to combined factors such as monomer chemistry, chain configuration, chain mobility, crystallinity, and permeation to water and oxygen, and product geometry. In this talk, we will discuss how these materials degrade and how the degradation depends on these factors under application conditions. Both experimental studies and mathematical modeling will be presented.

  2. Dielectric Actuation of Polymers

    Science.gov (United States)

    Niu, Xiaofan

    Dielectric polymers are widely used in a plurality of applications, such as electrical insulation, dielectric capacitors, and electromechanical actuators. Dielectric polymers with large strain deformations under an electric field are named dielectric elastomers (DE), because of their relative low modulus, high elongation at break, and outstanding resilience. Dielectric elastomer actuators (DEA) are superior to traditional transducers as a muscle-like technology: large strains, high energy densities, high coupling efficiency, quiet operation, and light weight. One focus of this dissertation is on the design of DE materials with high performance and easy processing. UV radiation curing of reactive species is studied as a generic synthesis methodology to provide a platform for material scientists to customize their own DE materials. Oligomers/monomers, crosslinkers, and other additives are mixed and cured at appropriate ratios to control the stress-strain response, suppress electromechanical instability of the resulting polymers, and provide stable actuation strains larger than 100% and energy densities higher than 1 J/g. The processing is largely simplified in the new material system by removal of the prestretching step. Multilayer stack actuators with 11% linear strain are demonstrated in a procedure fully compatible with industrial production. A multifunctional DE derivative material, bistable electroactive polymer (BSEP), is invented enabling repeatable rigid-to-rigid deformation without bulky external structures. Bistable actuation allows the polymer actuator to have two distinct states that can support external load without device failure. Plasticizers are used to lower the glass transition temperature to 45 °C. Interpenetrating polymer network structure is established inside the BSEP to suppress electromechanical instability, providing a breakdown field of 194 MV/m and a stable bistable strain as large as 228% with a 97% strain fixity. The application of BSEP

  3. Polymer Physics Prize Talk

    Science.gov (United States)

    Olvera de La Cruz, Monica

    Polymer electrolytes have been particularly difficult to describe theoretically given the large number of disparate length scales involved in determining their physical properties. The Debye length, the Bjerrum length, the ion size, the chain length, and the distance between the charges along their backbones determine their structure and their response to external fields. We have developed an approach that uses multi-scale calculations with the capability of demonstrating the phase behavior of polymer electrolytes and of providing a conceptual understanding of how charge dictates nano-scale structure formation. Moreover, our molecular dynamics simulations have provided an understanding of the coupling of their conformation to their dynamics, which is crucial to design self-assembling materials, as well as to explore the dynamics of complex electrolytes for energy storage and conversion applications.

  4. Nucleic Acid Polymers Are Active against Hepatitis Delta Virus Infection In Vitro.

    Science.gov (United States)

    Beilstein, Frauke; Blanchet, Matthieu; Vaillant, Andrew; Sureau, Camille

    2018-02-15

    In this study, an in vitro infection model for the hepatitis delta virus (HDV) was used to evaluate the antiviral effects of phosphorothioate nucleic acid polymers (NAPs) and investigate their mechanism of action. The results show that NAPs inhibit HDV infection at concentrations less than 4 μM in cultures of differentiated human hepatoma cells. NAPs were shown to be active at viral entry but inactive postentry on HDV RNA replication. Inhibition was independent of the NAP nucleotide sequence but dependent on both size and amphipathicity of the polymer. NAP antiviral activity was effective against HDV virions bearing the main hepatitis B virus (HBV) immune escape substitutions (D144A and G145R) and was pangenomic with regard to HBV envelope proteins. Furthermore, similar to immobilized heparin, immobilized NAPs could bind HDV particles, suggesting that entry inhibition was due, at least in part, to preventing attachment of the virus to cell surface glycosaminoglycans. The results document NAPs as a novel class of antiviral compounds that can prevent HDV propagation. IMPORTANCE HDV infection causes the most severe form of viral hepatitis in humans and one of the most difficult to cure. Currently, treatments are limited to long-term administration of interferon at high doses, which provide only partial efficacy. There is thus an urgent need for innovative approaches to identify new antiviral against HDV. The significance of our study is in demonstrating that nucleic acid polymers (NAPs) are active against HDV by targeting the envelope of HDV virions. In an in vitro infection assay, NAP activity was recorded at concentrations less than 4 μM in the absence of cell toxicity. Furthermore, the fact that NAPs could block HDV at viral entry suggests their potential to control the spread of HDV in a chronically HBV-infected liver. In addition, NAP anti-HDV activity was pangenomic with regard to HBV envelope proteins and not circumvented by HBsAg substitutions associated

  5. DNA Repair Systems

    Indian Academy of Sciences (India)

    DNA molecule which makes it ideal for storage and propagation of genetic information. ... of these errors are broadly referred to as DNA repair. DNA can ... changes occur in the human genome per day. ..... nails, frequent physical and mental.

  6. Conjugated polymer nanoparticles, methods of using, and methods of making

    KAUST Repository

    Habuchi, Satoshi

    2017-03-16

    Embodiments of the present disclosure provide for conjugated polymer nanoparticle, method of making conjugated polymer nanoparticles, method of using conjugated polymer nanoparticle, polymers, and the like.

  7. Conjugated polymer nanoparticles, methods of using, and methods of making

    KAUST Repository

    Habuchi, Satoshi; Piwonski, Hubert Marek; Michinobu, Tsuyoshi

    2017-01-01

    Embodiments of the present disclosure provide for conjugated polymer nanoparticle, method of making conjugated polymer nanoparticles, method of using conjugated polymer nanoparticle, polymers, and the like.

  8. Solid polymer electrolytes

    Science.gov (United States)

    Abraham, Kuzhikalail M.; Alamgir, Mohamed; Choe, Hyoun S.

    1995-01-01

    This invention relates to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of poly(vinyl sulfone) and lithium salts, and their use in all-solid-state rechargeable lithium ion batteries. The lithium salts comprise low lattice energy lithium salts such as LiN(CF.sub.3 SO.sub.2).sub.2, LiAsF.sub.6, and LiClO.sub.4.

  9. CLASSIFICATION OF BIODEGRADABLE POLYMERS

    Directory of Open Access Journals (Sweden)

    I. I. Karpunin

    2015-01-01

    Full Text Available The executed investigations have made it possible to ascertain that a morphological structure of starch granules mainly determine technological peculiarities of starch isolation from raw material, its modification and its later use. Morphological structure of starch granules primarily depends on type of plant starch-containing raw material which has been used for its isolation. Class of raw material exerts a strong impact on the shape and size of the granules. Linear “light” amylose chains and “heavy” amylopectin branch chains form a starch granule ultrastructure. X-ray research has proved that starch granules are characterized by presence of interlacing amorphous and crystalline regions. In this case polymer orientation using stretching of the obtained end product influences on its physical and mechanical  indices which are increasing due to polymer orientation. For the purpose of packaging orientation of polymer films can solve such important problems as significant improvement of operational properties, creation of  thermosetting film materials, improvement of qualitative indices of the recycled film.Results of the conducted research have proved the fact that it is necessary to make changes in technology in order to increase biological degradability of the recycled packaging made from polymers and improve physical and mechanical indices. In this regard film production technology presupposes usage of such substances as stark and others which are characterized by rather large presence of branch chains of molecules and interlacing amorphous and crystalline regions. Such approach makes it possible to obtain after-use package which is strong and quickly degradable by micro-organisms.

  10. Dynamics of polymers

    Energy Technology Data Exchange (ETDEWEB)

    Buchenau, U [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energieverfahrenstechnik

    1996-11-01

    Neutron scattering from amorphous polymers allows to switch from incoherent to coherent scattering in the same substance. The power of the tool for the study of the picosecond dynamics of disordered matter is illustrated for polybutadiene, polycarbonate and polystyrene. The results suggest a mixture of sound waves and localized modes, strongly interacting with each other, in the picosecond range. (author) 8 figs., tabs., 39 refs.

  11. Conjugated Polymer Solar Cells

    Science.gov (United States)

    2006-05-01

    thermal gravimetry analysis (TGA)............... 12 2.6 Photoluminescence (PL) spectroscopy... gravimetry analysis (TGA) Thermal analysis of polymer films has been accomplished by TGA and DSC methods with the aid of Perkin-Elmer Series 7 Analysers...The MEH-PPV/acceptor films were prepared by spin-casting of the resulting mixture (with or without precipitate ) on glass substrates of diameter 23 mm

  12. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  13. Luminescent lanthanide coordination polymers

    Energy Technology Data Exchange (ETDEWEB)

    Ma, L.; Evans, O.R.; Foxman, B.M.; Lin, W.

    1999-12-13

    One-dimensional lanthanide coordination polymers with the formula Ln(isonicotinate){sub 3}(H{sub 2}O){sub 2} (Ln = Ce, Pr, Nd, Sm, Eu, Tb; 1a-f) were synthesized by treating nitrate or perchlorate salts of Ln(III) with 4-pyridinecarboxaldehyde under hydro(solvo)thermal conditions. Single-crystal and powder X-ray diffraction studies indicate that these lanthanide coordination polymers adopt two different structures. While Ce(III), Pr(III), and Nd(III) complexes adopt a chain structure with alternating Ln-(carboxylate){sub 2}-Ln and Ln-(carboxylate){sub 4}-Ln linkages, Sm(III), Eu(III), and Tb(III) complexes have a doubly carboxylate-bridged infinite-chain structure with one chelating carboxylate group on each metal center. In both structures, the lanthanide centers also bind to two water molecules to yield an eight-coordinate, square antiprismatic geometry. The pyridine nitrogen atoms of the isonicotinate groups do not coordinate to the metal centers in these lanthanide(III) complexes; instead, they direct the formation of Ln(III) coordination polymers via hydrogen bonding with coordinated water molecules. Photoluminescence measurements show that Tb(isonicotinate){sub 3}(H{sub 2}O){sub 2} is highly emissive at room temperature with a quantum yield of {approximately}90%. These results indicate that highly luminescent lanthanide coordination polymers can be assembled using a combination of coordination and hydrogen bonds. Crystal data for 1a: monoclinic space group P2{sub 1}/c, a = 9.712(2) {angstrom}, b = 19.833(4) {angstrom}, c = 11.616(2) {angstrom}, {beta} = 111.89(3){degree}, Z = 4. Crystal data for 1f: monoclinic space group C2/c, a = 20.253(4) {angstrom}, b = 11.584(2) {angstrom}, c = 9.839(2) {angstrom}, {beta} = 115.64(3){degree}, Z = 8.

  14. Mechanoresponsive Healing Polymers

    Science.gov (United States)

    Gordon, Keith L. (Inventor); Siochi, Emilie J. (Inventor)

    2018-01-01

    Methods are provided to produce new mechanoresponsive healing systems. Additionally, various embodiments provide a two tier self-healing material system concept that provides a non-intrusive method to mitigate impact damage in a structure ranging from low velocity impact damage (e.g., crack damage) to high velocity impact damage (e.g., ballistic damage.) The various embodiments provide the mechanophore linked polymer PBG-BCB-PBG. The various embodiments provide methods for synthesizing PBG-BCB-PBG.

  15. Electrochemical polymer electrolyte membranes

    CERN Document Server

    Fang, Jianhua; Wilkinson, David P

    2015-01-01

    Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Discusses cutting-edge methodologies in PEM material selection and fabricationPoints out important challenges in developing PEMs and recommends mitigation strategies to improve PEM performanceAnalyzes the cur

  16. Fabrication of Defined Polydopamine Nanostructures by DNA Origami-Templated Polymerization.

    Science.gov (United States)

    Tokura, Yu; Harvey, Sean; Chen, Chaojian; Wu, Yuzhou; Ng, David Y W; Weil, Tanja

    2018-02-05

    A versatile, bottom-up approach allows the controlled fabrication of polydopamine (PD) nanostructures on DNA origami. PD is a biosynthetic polymer that has been investigated as an adhesive and promising surface coating material. However, the control of dopamine polymerization is challenged by the multistage-mediated reaction mechanism and diverse chemical structures in PD. DNA origami decorated with multiple horseradish peroxidase-mimicking DNAzyme motifs was used to control the shape and size of PD formation with nanometer resolution. These fabricated PD nanostructures can serve as "supramolecular glue" for controlling DNA origami conformations. Facile liberation of the PD nanostructures from the DNA origami templates has been achieved in acidic medium. This presented DNA origami-controlled polymerization of a highly crosslinked polymer provides a unique access towards anisotropic PD architectures with distinct shapes that were retained even in the absence of the DNA origami template. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  17. Nonequilibrium thermodynamics of dilute polymer solutions in flow.

    Science.gov (United States)

    Latinwo, Folarin; Hsiao, Kai-Wen; Schroeder, Charles M

    2014-11-07

    Modern materials processing applications and technologies often occur far from equilibrium. To this end, the processing of complex materials such as polymer melts and nanocomposites generally occurs under strong deformations and flows, conditions under which equilibrium thermodynamics does not apply. As a result, the ability to determine the nonequilibrium thermodynamic properties of polymeric materials from measurable quantities such as heat and work is a major challenge in the field. Here, we use work relations to show that nonequilibrium thermodynamic quantities such as free energy and entropy can be determined for dilute polymer solutions in flow. In this way, we determine the thermodynamic properties of DNA molecules in strong flows using a combination of simulations, kinetic theory, and single molecule experiments. We show that it is possible to calculate polymer relaxation timescales purely from polymer stretching dynamics in flow. We further observe a thermodynamic equivalence between nonequilibrium and equilibrium steady-states for polymeric systems. In this way, our results provide an improved understanding of the energetics of flowing polymer solutions.

  18. BioArtificial polymers

    Science.gov (United States)

    Szałata, Kamila; Gumi, Tania

    2017-07-01

    Nowadays, the polymer science has impact in practically all life areas. Countless benefits coming from the usage of materials with high mechanical and chemical resistance, variety of functionalities and potentiality of modification drive to the development of new application fields. Novel approaches of combining these synthetic substances with biomolecules lead to obtain multifunctional hybrid conjugates which merge the bioactivity of natural component with outstanding properties of artificial polymer. Over the decades, an immense progress in bioartificial composites domain allowed to reach a high level of knowledge in terms of natural-like systems engineering, leading to diverse strategies of biomolecule immobilization. Together with different available options, including covalent and noncovalent attachment, come various challenges, related mainly with maintaining the biological activity of fixed molecules. Even though the amount of applications that achieve commercial status is still not substantial, and is expanding continuously in the disciplines like "smart materials," biosensors, delivery systems, nanoreactors and many others. A huge number of remarkable developments reported in the literature present a potential of bioartificial conjugates as a fabrics with highly controllable structure and multiple functionalities, serving as a powerful nanotechnological tool. This novel approach brings closer biologists, chemists and engineers, who sharing their effort and complementing the knowledge can revolutionize the field of bioartificial polymer science.

  19. Synthesis of DNA

    Science.gov (United States)

    Mariella, Jr., Raymond P.

    2008-11-18

    A method of synthesizing a desired double-stranded DNA of a predetermined length and of a predetermined sequence. Preselected sequence segments that will complete the desired double-stranded DNA are determined. Preselected segment sequences of DNA that will be used to complete the desired double-stranded DNA are provided. The preselected segment sequences of DNA are assembled to produce the desired double-stranded DNA.

  20. Phases of polymer systems in solution studied via molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Joshua Allen [Iowa State Univ., Ames, IA (United States)

    2009-05-01

    Polymers are amazingly versatile molecules with a tremendous range of applications. Our lives would be very different without them. There would be no multitudes of plastic encased electronic gizmos, no latex paint on the walls and no rubber tires, just to name a few of the many commonplace polymer materials. In fact, life as we know it wouldn’t exist without polymers as two of the most essential types of molecules central to cellular life, Proteins and DNA, are both polymers! [1] With their wide range of application to a variety of uses, polymers are still a very active field in basic research. Of particular current interest is the idea of combining polymers with inorganic particles to form novel composite materials. [2] As computers are becoming faster, they are becoming all the more powerful tools for modeling and simulating real systems. With recent advances in computing on graphics processing units (GPUs) [3–7], questions can now be answered via simulation that could not even be asked before. This thesis focuses on the use of computer simulations to model novel polymerinorganic composite systems in order to predict what possible phases can form and under what conditions. The goal is to provide some direction for future experiments and to gain a deeper understanding of the fundamental physics involved. Along the way, there are some interesting and essential side-tracks in the areas of equilibrating complicated phases and accelerating the available computer power with GPU computing, both of which are necessary steps to enable the study of polymer nanocomposites.

  1. Polymers for IUdR radiosensitization of experimental glioblastoma

    International Nuclear Information System (INIS)

    Williams, Jeffery A.; Xuan Yuan; Brem, Henry

    1997-01-01

    R (fluorescein isothiocyanate (FITC) labeled anti-IUdR antibody) and for DNA (propidium iodide). Toxicity: Groups of at ≥ 5 non-tumor bearing mice had i.c. implantation of empty (control) or experimental (50% IUdR) polymers (Day 0) alone or combined with cranial external beam irradiation (5 Gy x 2 on days 7 and 8 vs. 2 Gy BID on days 7-10) given via a calibrated 137-Cs irradiator. For in vivo radiosensitization, groups of ≥ 8 mice had sequential i.c. inoculation (2 x 10 5 cells on day 0), craniectomy and implantation of empty (control) or experimental (50% IUdR) polymers, and irradiation. To explore the effect of the timing and escalation of the radiation dose, the interval from implantation of polymers until radiation were: Expt 1:) 5 days (5 Gy on days 7 and 8 (10 Gy total)) vs. Expt 2:) 4 or 7 days (2 Gy BID x 4 on days 7-10 (16 Gy total)). Survival was recorded. Results: In vitro: The polymer provides controlled release of IUdR. After 4 days the cumulative percentages released were 43.7 ± 0.1, 70.0 ± 0.2, and 90.2 ± 0.2 (p 10 ) was -2.02 ± 0.02 or -3.68 ± 0.11 (p < 0.001), respectively. In vivo: Release: The measured activity (cpm) of i.c. 125-IUdR polymers showed protracted decrease vs. time. The proportions of implanted activity were 0.86 ± 0.08, 0.77 ± 0.10, 0.30 ± 0.03 and 0.07 ± 0.01 measured 23, 43, 120 and 311 hours, respectively, after implantation. IUdR polymers caused high tumor labeling. When measured 4 vs. 8 days after IUdR polymer implantation, the mean percentages (± SEM) of labeled tumor cells 0 (coplanar with polymer), 1 and 2 mm distant were striking: 67 ± 11, 42 ± 4, and 32 ± 9 vs. 54 ± 8, 48 ± 5 and 12 ± 4 (p = NS day 4 vs. 8), respectively. Toxicity: No deaths were recorded 80 days after polymer vs. combined polymer and radiation treatments. Radiosensitization: Expt 1: The median survival (d) was 15 for empty polymers alone vs. 16 (p = NS) or 17 (p = NS) for IUdR polymers alone or no treatment, respectively. Survival after empty vs

  2. Synthetic approaches to uniform polymers.

    Science.gov (United States)

    Ali, Monzur; Brocchini, Steve

    2006-12-30

    Uniform polymers are characterised by a narrow molecular weight distribution (MWD). Uniformity is also defined by chemical structure in respect of (1) monomer orientation, sequence and stereo-regularity, (2) polymer shape and morphology and (3) chemical functionality. The function of natural polymers such as polypeptides and polynucleotides is related to their conformational structure (e.g. folded tertiary structure). This is only possible because of their high degree of uniformity. While completely uniform synthetic polymers are rare, polymers with broad structure and MWD are widely used in medicine and the biomedical sciences. They are integral components in final dosage forms, drug delivery systems (DDS) and in implantable devices. Increasingly uniform polymers are being used to develop more complex medicines (e.g. delivery of biopharmaceuticals, enhanced formulations or DDS's for existing actives). In addition to the function imparted by any new polymer it will be required to meet stringent specifications in terms of cost containment, scalability, biocompatibility and performance. Synthetic polymers with therapeutic activity are also being developed to exploit their polyvalent properties, which is not possible with low molecular weight molecules. There is need to utilise uniform polymers for applications where the polymer may interact with the systemic circulation, tissues or cellular environment. There are also potential applications (e.g. stimuli responsive coatings) where uniform polymers may be used for their more defined property profile. While it is not yet practical to prepare synthetic polymers to the same high degree of uniformity as proteins, nature also effectively utilises many polymers with lower degrees of uniformity (e.g. polysaccharides, poly(amino acids), polyhydroxyalkanoates). In recent years it has become possible to prepare with practical experimental protocols sufficient quantities of polymers that display many aspects of uniformity. This

  3. Investigation of the charge effect on the electrochemical transduction in a quinone-based DNA sensor

    DEFF Research Database (Denmark)

    Reisberg, S.; Piro, B.; Noel, V.

    2008-01-01

    To elucidate the mechanism involved in the electrochemical transduction process of a conducting polymer-based DNA sensor, peptide nucleic acids (PNA) were used. PNA are DNA analogues having similar hybridization properties but are neutral. This allows to discriminate the electrostatic effect of D...... strands from the steric hindrance generated on the bioelectrode upon hybridization. It can be concluded that DNA conformational changes are determinant in the transduction process and that the electrostatic effect is negligible....

  4. Biomolecule-functionalized polymer brushes.

    Science.gov (United States)

    Jiang, Hui; Xu, Fu-Jian

    2013-04-21

    Functional polymer brushes have been utilized extensively for the immobilization of biomolecules, which is of crucial importance for the development of biosensors and biotechnology. Recent progress in polymerization methods, in particular surface-initiated atom transfer radical polymerization (ATRP), has provided a unique means for the design and synthesis of new biomolecule-functionalized polymer brushes. This current review summarizes such recent research activities. The different preparation strategies for biomolecule immobilization through polymer brush spacers are described in detail. The functional groups of the polymer brushes used for biomolecule immobilization include epoxide, carboxylic acid, hydroxyl, aldehyde, and amine groups. The recent research activities indicate that functional polymer brushes become versatile and powerful spacers for immobilization of various biomolecules to maximize their functionalities. This review also demonstrates that surface-initiated ATRP is used more frequently than other polymerization methods in the designs of new biomolecule-functionalized polymer brushes.

  5. Claisen thermally rearranged (CTR) polymers

    Science.gov (United States)

    Tena, Alberto; Rangou, Sofia; Shishatskiy, Sergey; Filiz, Volkan; Abetz, Volker

    2016-01-01

    Thermally rearranged (TR) polymers, which are considered the next-generation of membrane materials because of their excellent transport properties and high thermal and chemical stability, are proven to have significant drawbacks because of the high temperature required for the rearrangement and low degree of conversion during this process. We demonstrate that using a [3,3]-sigmatropic rearrangement, the temperature required for the rearrangement of a solid glassy polymer was reduced by 200°C. Conversions of functionalized polyimide to polybenzoxazole of more than 97% were achieved. These highly mechanically stable polymers were almost five times more permeable and had more than two times higher degrees of conversion than the reference polymer treated under the same conditions. Properties of these second-generation TR polymers provide the possibility of preparing efficient polymer membranes in a form of, for example, thin-film composite membranes for various gas and liquid membrane separation applications. PMID:27482538

  6. Terminology of Polymers Containing Ionizable or Ionic Groups and of Polymers Containing Ions, VII.3

    Directory of Open Access Journals (Sweden)

    Jarm, V.

    2009-10-01

    Full Text Available The class of ionic polymers has widespread application in many areas of everyday life, in industrial production, and in the processes of living matter. The properties of ionic polymers depend on the polymer structure, and the nature, content, and location of the ionic groups. To clear differences among various ionic polymers, the IUPAC recommendations present 34 definitionsfor the ionomer, polyacid, polybase, polyampholytic polymer, ion-exchange polymer, polybetaine, polyelectrolyte, intrinsically conducting polymer, solid polymer electrolyte, etc

  7. Solid polymer electrolyte lithium batteries

    Science.gov (United States)

    Alamgir, Mohamed; Abraham, Kuzhikalail M.

    1993-01-01

    This invention pertains to Lithium batteries using Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized in a solid organic polymer matrix. In particular, this invention relates to Li batteries using solid polymer electrolytes derived by immobilizing solvates formed between a Li salt and an aprotic organic solvent (or mixture of such solvents) in poly(vinyl chloride).

  8. Vacuum ultraviolet photochemistry of polymers

    International Nuclear Information System (INIS)

    Skurat, Vladimir

    2003-01-01

    The interaction of vacuum UV radiation (wavelength range from 1 to 200 nm) with polymers is interesting for fundamental and applied sciences. This interest is stimulated by various reasons: - Wide applications of polymeric materials in semiconductor technology, where they are used as photoresist materials in combination with VUV light sources (lasers, excimer lamps, synchrotron radiation and others). - Polymers are widely used as spacecraft materials in the last 20 years. On near-Earth orbits, the polymeric materials of spacecraft surfaces are destroyed by solar radiation. - VUV radiation is one of the components of gas discharge plasmas, which are used for treatment of polymer, with the aim of modifying their surface properties. The main features of interaction of VUV radiation with polymers are discussed. The spectra of intrinsic absorption of saturated polymers (polyethylene, polypropylene, polytetrafluoroethylene and others) are situated mainly in the VUV region. The photochemistry of polymers in the VUV region is very different from their photochemistry at wavelengths longer than 200 nm, where the absorption spectra belong to impurities and polymer defects. The polymer photochemistry in the VUV region is wavelength-dependent. At wavelengths longer than about 140 nm, the main role is played by transformations of primary-formed singlet excited molecules. At shorter wavelengths the role of photoionization increases progressively and the main features of VUV photolysis become similar to the picture of radiolysis, with significant contributions of charge pairs and triplet excited molecules. Very important features of VUV light absorption in polymers are high absorption coefficients. Because of this, the surface layers absorb large doses of energy. This leads to very profound transformation of material on the polymer surface. In particular for polymers which are considered destroyed by radiation (for example, perfluoropolymers), this leads to VUV-induced erosion

  9. Planar-Processed Polymer Transistors.

    Science.gov (United States)

    Xu, Yong; Sun, Huabin; Shin, Eul-Yong; Lin, Yen-Fu; Li, Wenwu; Noh, Yong-Young

    2016-10-01

    Planar-processed polymer transistors are proposed where the effective charge injection and the split unipolar charge transport are all on the top surface of the polymer film, showing ideal device characteristics with unparalleled performance. This technique provides a great solution to the problem of fabrication limitations, the ambiguous operating principle, and the performance improvements in practical applications of conjugated-polymer transistors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Conjugated Polymers for Energy Production

    DEFF Research Database (Denmark)

    Livi, Francesco

    This dissertation is aimed at developing materials for flexible, large area, ITO-free polymer solar cells (PSCs) fully printed under ambient conditions. A large screening of conjugated polymers, both novel and well-known materials, has been carried out in order to find suitable candidates...... polymerization method for industrial production of polymers. Several DArP protocols have been employed for the synthesis of PPDTBT leading to polymers with high structural regularity and photovoltaic performances comparable with the same materials synthesized via Stille cross-coupling polymerization...

  11. Multifunctional Polymer/Inorganic Nanocomposites

    National Research Council Canada - National Science Library

    Manias, E

    2003-01-01

    ... in multifunctional nanocomposite materials. Understanding the structure/property relations in polymer/clay nanocomposites is of great importance in designing materials with desired sets of properties...

  12. Wear of polymers and composites

    CERN Document Server

    Abdelbary, Ahmed

    2015-01-01

    In the field of tribology, the wear behaviour of polymers and composite materials is considered a highly non-linear phenomenon. Wear of Polymers and Composites introduces fundamentals of polymers and composites tribology. The book suggests a new approach to explore the effect of applied load and surface defects on the fatigue wear behaviour of polymers, using a new tribometer and thorough experiments. It discusses effects of surface cracks, under different static and cyclic loading parameters on wear, and presents an intelligent algorithm, in the form of a neural network, to map the relations

  13. Application of Composite Polymer Electrolytes

    National Research Council Canada - National Science Library

    Scrosati, Bruno

    2001-01-01

    ...)PEO-based composite polymer electrolytes, by a series of specifically addressed electrochemical tests which included the determination of the conductivity and of the lithium transference number...

  14. Sustainable polymers from renewable resources.

    Science.gov (United States)

    Zhu, Yunqing; Romain, Charles; Williams, Charlotte K

    2016-12-14

    Renewable resources are used increasingly in the production of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manufacture of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites. Efficient catalysis is required to produce monomers, to facilitate selective polymerizations and to enable recycling or upcycling of waste materials. There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging. Life-cycle assessment can be used to quantify the environmental benefits of sustainable polymers.

  15. Phenomenology of polymer solution dynamics

    National Research Council Canada - National Science Library

    Phillies, George D. J

    2011-01-01

    ... solutions, not dilute solutions or polymer melts. From centrifugation and solvent dynamics to viscosity and diffusion, experimental measurements and their quantitative representations are the core of the discussion...

  16. Small angle scattering and polymers

    International Nuclear Information System (INIS)

    Cotton, J.P.

    1996-01-01

    The determination of polymer structure is a problem of interest for both statistical physics and industrial applications. The average polymer structure is defined. Then, it is shown why small angle scattering, associated with isotopic substitution, is very well suited to the measurement of the chain conformation. The corresponding example is the old, but pedagogic, measurement of the chain form factor in the polymer melt. The powerful contrast variation method is illustrated by a recent determination of the concentration profile of a polymer interface. (author) 12 figs., 48 refs

  17. Polymer Processing and Characterization Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The purpose is to process and evaluate polymers for use in nonlinear optical, conductive and structural Air Force applications. Primary capabilities are extrusion of...

  18. Physical association of pyrimidine dimer DNA glycosylase and apurinic/apyrimidinic DNA endonuclease essential for repair of ultraviolet-damaged DNA

    International Nuclear Information System (INIS)

    Nakabeppu, Y.; Sekiguchi, M.

    1981-01-01

    T4 endonuclease, which is involved in repair of uv-damaged DNA, has been purified to apparent physical homogeneity. Incubation of uv-irradiated poly(dA).poly(dT) with the purified enzyme preparations resulted in production of alkali-labile apyrimidinic sites, followed by formation of nicks in the polymer. By performing a limited reaction with T4 endonuclease V at pH 8.5, irradiated polymer was converted to an intermediate form that carried a large number of alkali-labile sites but only a few nicks. The intermediate was used as substrate for the assay of apurinic/apyrimidinic DNA endonuclease activity. The two activities, a pyrimidine dimer DNA glycosylase and an apurinic/apyrimidinic DNA endonuclease, were copurified and found in enzyme preparations that contained only a 16,000-dalton polypeptide. These results strongly suggested that a DNA glycosylase specific for pyrimidine dimers and an apurinic/apyrimidinic DNA endonuclease reside in a single polypeptide chain coded by the denV gene of bacteriophage T4

  19. Enzymatic Production of Monoclonal Stoichiometric Single-Stranded DNA Oligonucleotides

    Science.gov (United States)

    Ducani, Cosimo; Kaul, Corinna; Moche, Martin; Shih, William M.; Högberg, Björn

    2013-01-01

    Single-stranded oligonucleotides are important as research tools as probes for diagnostics and gene therapy. Today, production of oligonucleotides is done via solid-phase synthesis. However, the capabilities of current polymer chemistry are limited in comparison to what can be produced in biological systems. The errors in synthetic DNA increases with oligonucleotide length, and sequence diversity can often be a problem. Here, we present the Monoclonal Stoichiometric (MOSIC) method for enzymatic DNA oligonucleotide production. Using this method, we amplify oligonucleotides from clonal templates followed by digestion of a cutter-hairpin, resulting in pools of monoclonal oligonucleotides with precisely controlled relative stoichiometric ratios. We present data where MOSIC oligonucleotides, 14–378 nt long, were prepared either by in vitro rolling-circle amplification, or by amplification in Escherichia coli in the form of phagemid DNA. The formation of a DNA crystal and folding of DNA nanostructures confirmed the scalability, purity and stoichiometry of the produced oligonucleotides. PMID:23727986

  20. A non-covalent peptide-based carrier for in vivo delivery of DNA mimics.

    Science.gov (United States)

    Morris, May C; Gros, Edwige; Aldrian-Herrada, Gudrun; Choob, Michael; Archdeacon, John; Heitz, Frederic; Divita, Gilles

    2007-01-01

    The dramatic acceleration in identification of new nucleic-acid-based therapeutic molecules has provided new perspectives in pharmaceutical research. However, their development is limited by their poor cellular uptake and inefficient trafficking. Here we describe a short amphipathic peptide, Pep-3, that combines a tryptophan/phenylalanine domain with a lysine/arginine-rich hydrophilic motif. Pep-3 forms stable nano-size complexes with peptide-nucleic acid analogues and promotes their efficient delivery into a wide variety of cell lines, including primary and suspension lines, without any associated cytotoxicity. We demonstrate that Pep-3-mediated delivery of antisense-cyclin B1-charged-PNA blocks tumour growth in vivo upon intratumoral and intravenous injection. Moreover, we show that PEGylation of Pep-3 significantly improves complex stability in vivo and consequently the efficiency of antisense cyclin B1 administered intravenously. Given the biological characteristics of these vectors, we believe that peptide-based delivery technologies hold a true promise for therapeutic applications of DNA mimics.

  1. Clickable antifouling polymer brushes for polymer pen lithography

    Czech Academy of Sciences Publication Activity Database

    Bog, U.; de los Santos Pereira, Andres; Mueller, S. L.; Havenridge, S.; Parrillo, Viviana; Bruns, M.; Holmes, A. E.; Rodriguez-Emmenegger, C.; Fuchs, H.; Hirtz, M.

    2017-01-01

    Roč. 9, č. 13 (2017), s. 12109-12117 ISSN 1944-8244 R&D Projects: GA ČR(CZ) GJ15-09368Y Institutional support: RVO:61389013 Keywords : antifouling * biofunctional interfaces * polymer brushes Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 7.504, year: 2016

  2. Enhancement of Polymer Cytocompatibility by Nanostructuring of Polymer Surface

    Czech Academy of Sciences Publication Activity Database

    Slepička, P.; Kasálková-Slepičková, N.; Bačáková, Lucie; Kolská, Z.; Švorčík, V.

    2012-01-01

    Roč. 2012, č. 2012 (2012), ID527403 ISSN 1687-4110 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:67985823 Keywords : polymer cytocompatibility * polymer surface * nanotechnology Subject RIV: EI - Biotechnology ; Bionics Impact factor: 1.547, year: 2012

  3. Radiation Synthesis of Superabsorbent Polymers Based on Natural Polymers

    International Nuclear Information System (INIS)

    Sen, Murat; Hayrabolulu, Hande

    2010-01-01

    The objectives of proposed research contract were first synthesize superabsorbent polymers based on natural polymers to be used as disposable diapers and soil conditioning materials in agriculture, horticulture and other super adsorbent using industries. We have planned to use the natural polymers; locust beam gum, tara gum, guar gum and sodium alginate on the preparation of natural superabsorbent polymers(SAP). The aqueous solution of natural polymers and their blends with trace amount of monomer and cross-linking agents will be irradiated in paste like conditions by gamma rays for the preparation of cross-linked superabsorbent systems. The water absorption and deswellling capacity of prepared super adsorbents and retention capacity, absorbency under load, suction power, swelling pressure and pet-rewet properties will be determined. Use of these materials instead of synthetic super absorbents will be examined by comparing the performance of finished products. The experimental studies achieved in the second year of project mainly on the effect of radiation on the chemistry of sodium alginate polymers in different irradiation conditions and structure-property relationship particularly with respect to radiation induced changes on the molecular weight of natural polymers and preliminary studies on the synthesis of natural-synthetic hydride super adsorbent polymers were given in details

  4. Polymer solidification national program

    International Nuclear Information System (INIS)

    Kalb, P.D.; Colombo, P.

    1993-04-01

    Brookhaven National Laboratory (BNL) has developed several new and innovative polymer processes for the solidification of low-level radioactive, hazardous and mixed wastes streams. Polyethylene and modified sulfur cement solidification technologies have undergone steady, gradual development at BNL over the past nine years. During this time they have progressed through each of the stages necessary for logical technology maturation: from process conception, parameter optimization, waste form testing, evaluation of long-term durability, economic analysis, and scale-up feasibility. This technology development represents a significant investment which can potentially provide DOE with both short- and long-term savings

  5. Monte Carlo simulations of confined polymer systems

    NARCIS (Netherlands)

    Vliet, Johannes Henricus van

    1991-01-01

    This thesis considers confined polymer systems. These systems are of considerable interest, e.g., thin polymer films, chromotography of polymer solutions, drag reduction, enhanced oil recovery, stabilization of colloidal dispersions, lubrication and biolubrication. The method used to study these

  6. Processing of polymers using reactive solvents

    NARCIS (Netherlands)

    Lemstra, P.J.; Kurja, J.; Meijer, H.E.H.; Meijer, H.E.H.

    1997-01-01

    A review with many refs. on processing of polymers using reactive solvents including classification of synthetic polymers, guidelines for the selection of reactive solvents, basic aspects of processing, examples of intractable and tractable polymer/reactive solvent system

  7. Facile preparation of a DNA sensor for rapid herpes virus detection

    Energy Technology Data Exchange (ETDEWEB)

    Tam, Phuong Dinh, E-mail: tampd-hast@mail.hut.edu.vn [Hanoi Advanced School of Science and Technology, Hanoi University of Technology (Viet Nam); Tuan, Mai Anh, E-mail: tuanma-itims@mail.hut.edu.vn [International Training Institute for Materials Science, Hanoi University of Technology (Viet Nam); Huy, Tran Quang [National Institute of Hygiene and Epidemiology (NIHE), 01 Yersin, Hai Ba Trung District, Hanoi (Viet Nam); Le, Anh-Tuan [Hanoi Advanced School of Science and Technology, Hanoi University of Technology (Viet Nam); Hieu, Nguyen Van, E-mail: hieu@itims.edu.vn [International Training Institute for Materials Science, Hanoi University of Technology (Viet Nam)

    2010-10-12

    In this paper, a simple DNA sensor platform was developed for rapid herpes virus detection in real samples. The deoxyribonucleic acid (DNA) sequences of the herpes simplex virus (DNA probe) were directly immobilized on the surface of interdigitated electrodes by electrochemical polymerization along with pyrrole monomers. The potential was scanned from - 0.7 to + 0.6 V, and the scanning rate was 100 mV/s. Fourier transform infrared spectroscopy was employed to verify specific DNA sequence binding and the conducting polymer. The morphology of the conducting polymer doped with DNA strands was characterized using a field emission scanning electron microscope. As-obtained DNA sensor was used to detect the herpes virus DNA in the real samples. The results show that the current DNA sensors detected the lowest DNA concentration of 2 nM. This sensitivity appears to be better than that of the DNA sensors prepared by immobilization of the DNA probe on the 3-aminopropyl-triethoxy-silance (APTS) membrane.

  8. Facile preparation of a DNA sensor for rapid herpes virus detection

    International Nuclear Information System (INIS)

    Tam, Phuong Dinh; Tuan, Mai Anh; Huy, Tran Quang; Le, Anh-Tuan; Hieu, Nguyen Van

    2010-01-01

    In this paper, a simple DNA sensor platform was developed for rapid herpes virus detection in real samples. The deoxyribonucleic acid (DNA) sequences of the herpes simplex virus (DNA probe) were directly immobilized on the surface of interdigitated electrodes by electrochemical polymerization along with pyrrole monomers. The potential was scanned from - 0.7 to + 0.6 V, and the scanning rate was 100 mV/s. Fourier transform infrared spectroscopy was employed to verify specific DNA sequence binding and the conducting polymer. The morphology of the conducting polymer doped with DNA strands was characterized using a field emission scanning electron microscope. As-obtained DNA sensor was used to detect the herpes virus DNA in the real samples. The results show that the current DNA sensors detected the lowest DNA concentration of 2 nM. This sensitivity appears to be better than that of the DNA sensors prepared by immobilization of the DNA probe on the 3-aminopropyl-triethoxy-silance (APTS) membrane.

  9. Entanglements in Conjugated Polymers

    Science.gov (United States)

    Xie, Renxuan; Lee, Youngmin; Aplan, Melissa; Caggiano, Nick; Gomez, Enrique; Colby, Ralph

    Conjugated polymers, such as poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly-((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (PFTBT), are widely used as hole and electron transport materials in a variety of electronic devices. However, fundamental knowledge regarding chain entanglements and nematic-to-isotropic transition is still lacking and are crucial to maximize charge transport properties. A systematic melt rheology study on P3HT with various molecular weights and regio regularities was performed. We find that the entanglement molecular weight Me is 5.0 kg/mol for regiorandom P3HT, but the apparent Me for regioregular P3HT is significantly higher. The difference is postulated to arise from the presence of a nematic phase only in regioregular P3HT. Analogously, PFTBT shows a clear rheological signature of the nematic-to-isotropic transition as a reversible sharp transition at 278 C. Shearing of this nematic phase leads to anisotropic crystalline order in PFTBT. We postulate that aligning the microstructure will impact charge transport and thereby advance the field of conducting polymers. National Science Foundation.

  10. Polymer article of manufacture

    Energy Technology Data Exchange (ETDEWEB)

    Newlove, J.C.; McDougall, L.A.

    1987-12-15

    It is an object of this invention to provide an article and its use to enhance the production of hydrocarbons from geologial reservoirs, more particularly from fractured formations. It has been an additional object to devise a composition for providing controlled release of a reagent downhole, in a pipeline, in other oil-containing environments or fluids. It has been discovered that it is possible to provide for the introduction of an additive reagent into a liquid hydrocarbon by providing solid polymeric bodies each comprising a polymeric matrix containing a substantially water insoluble reagent such as a wax crystal modifier, demulsifier, scale inhibitor, corrosion inhibitor, biocide, ashless dispersant, antioxidant and mixtures thereof. These bodies are, in use, positioned at a location where it is desired to release the reagent into the substantially hydrocarbon fluid and, upon contact with fluid in this location, active reagent is released into the fluid. Thus in accordance with this invention there is provided a solid polymeric body comprising a polymer matrix containing a substantially water-insoluble reagent leachable into a substantially hydrocarbon liquid environment. The object of this invention has been realized in specific form by beads comprising a copolymeric matrix of methylmethacrylate and methacrylic acid containing the behenyl half ester of a C/sub 24/-C/sub 28/ alkenyl succinic anhydride polymer and having a diameter ranging from 0.2 to 1 mm. Such beads, when introduced downhole in a hydraulic fracturing operation, were found to inhibit paraffin wax deposition.

  11. Polymer dye lasers

    DEFF Research Database (Denmark)

    Balslev, Søren

    2006-01-01

    , elektronstrålelithografi og Röntgenstrålelithografi. Andre polymerer er også blevet formgivet via ”nanoimprint” lithografi for at skabe laserresonatorer. En række lasere, både baseret på et flydende forstærkningsmedium og et faststof forstærkningsrmedium er blevet udviklet. Laserne giver både lys i flere ”modes” og i een......Formålet med dette Ph.D. arbejde har været at udvikle miniaturiserede polymer farvestoflasere, egnet til at blive integreret i mikrochips som også indeholder andre polymerstrukturer – som for eksempel kan findes i ”Laboratorie-på-en-chip” kredsløb. Lasernes funktion skal være at levere lys til...... meget følsomme sensorformål, og at undgå at skulle opliniere eksterne lyskilder til sensorer på polymerchips. En enkelt type gennemsigtig ”resist” (SU-8) er blevet brugt til at udvikle en række laserresonatorer i polymer. ”Resisten” er blevet formgivet via en række lithografiske teknikker: UV lithografi...

  12. Homogeneous crystal nucleation in polymers.

    Science.gov (United States)

    Schick, C; Androsch, R; Schmelzer, J W P

    2017-11-15

    The pathway of crystal nucleation significantly influences the structure and properties of semi-crystalline polymers. Crystal nucleation is normally heterogeneous at low supercooling, and homogeneous at high supercooling, of the polymer melt. Homogeneous nucleation in bulk polymers has been, so far, hardly accessible experimentally, and was even doubted to occur at all. This topical review summarizes experimental findings on homogeneous crystal nucleation in polymers. Recently developed fast scanning calorimetry, with cooling and heating rates up to 10 6 K s -1 , allows for detailed investigations of nucleation near and even below the glass transition temperature, including analysis of nuclei stability. As for other materials, the maximum homogeneous nucleation rate for polymers is located close to the glass transition temperature. In the experiments discussed here, it is shown that polymer nucleation is homogeneous at such temperatures. Homogeneous nucleation in polymers is discussed in the framework of the classical nucleation theory. The majority of our observations are consistent with the theory. The discrepancies may guide further research, particularly experiments to progress theoretical development. Progress in the understanding of homogeneous nucleation is much needed, since most of the modelling approaches dealing with polymer crystallization exclusively consider homogeneous nucleation. This is also the basis for advancing theoretical approaches to the much more complex phenomena governing heterogeneous nucleation.

  13. Developments in polymer degradation - 7

    International Nuclear Information System (INIS)

    Grassie, N.

    1987-01-01

    A selection of topics which are representative of the continually expanding area of polymer degradation is presented. The aspects emphasised include the products of degradation of specific polymers, degradation by high energy radiation and mechanical forces, fire retardant studies and the special role of small radicals in degradation processes. (author)

  14. Wood and concrete polymer composites

    International Nuclear Information System (INIS)

    Singer, K.

    1974-01-01

    There are several ways to prepare and use wood and concrete polymer composites. The most important improvements in the case of concrete polymer composites are obtained for compressive and tensile strengths. The progress in this field in United States and other countries is discussed in this rview. (M.S.)

  15. All-Polymer Electrochemical Sensors

    DEFF Research Database (Denmark)

    Kafka, Jan Robert

    This thesis presents fabrication strategies to produce different types of all-polymer electrochemical sensors based on electrodes made of the highly conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Three different systems are presented, fabricated either by using microdrilling or by hot...

  16. Degradable polymers for tissue engineering

    NARCIS (Netherlands)

    van Dijkhuizen-Radersma, Riemke; Moroni, Lorenzo; van Apeldoorn, Aart A.; Zhang, Zheng; Grijpma, Dirk W.; van Blitterswijk, Clemens A.

    2008-01-01

    This chapter elaborates the degradable polymers for tissue engineering and their required scaffold material in tissue engineering. It recognizes the examples of degradable polymers broadly used in tissue engineering. Tissue engineering is the persuasion of the body to heal itself through the

  17. Graphene-based polymer nanocomposites

    NARCIS (Netherlands)

    Tkalya, E.

    2012-01-01

    The main reason for the rapid development of polymer composite materials is that the traditional "pure" polymers have largely played out its performance capabilities whereas technology requires materials with new properties and advances. There are a number of advantages polymeric composites have

  18. Contact mechanics in glassy polymers

    NARCIS (Netherlands)

    Breemen, van L.C.A.

    2009-01-01

    Polymers, primarily semi-crystalline, are widely used in applications where low friction is required; examples are cups in artificial hip joints, bearings and gears. Until now there is no clear indication why some polymers display low friction and others don’t. In this thesis a systematic

  19. Radiation synthesis of polymer polyol

    International Nuclear Information System (INIS)

    Guo Jianmei; Zeng Xinmiao; Zhou Chengfei; Cao Wei; Zhai Tong; Wu Dezhen

    2010-01-01

    The polymer polyol was synthesized by γ irradiation. The properties of polymer polyol synthesized with different radiation dose were studied. The experiment result showed the radiation dose hadn't significant influence on the hydroxyl value of polymer polyol. The sample with different solid content had different hydroxyl value. When the radiation dose is between 1 to 12 kGy, the viscosity and hydroxyl value of polymer polyol were increased with the increment of radiation dose. When radiation dose is between 1 to 12 kGy, with the increment of radiation dose, viscosity of polymer polyol was rapidly increased, and the content solid of sample has few change. When radiation dose is higher than 20 kGy, the viscosity and hydroxyl value of polymer polyol have gradually increase with the increment of radiation dose. The size of polymer particles is 0.1-0.6 μm. The value of 150 mesh filter was 100%. The polymer polyol may be used as PU foam and elastomer. (authors)

  20. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...

  1. Fifty years of polymer science

    NARCIS (Netherlands)

    Du Prez, Filip; Hoogenboom, Richard; Klumperman, Bert; Meier, Michael; Monteiro, Michael; Müller, Alejandro; Vancso, Gyula J.

    2015-01-01

    The European Polymer Journal (EPJ) has been serving the scientific community for 50 years, which makes it one of the older macromolecular journals with a broad focus. Since its launch 50 years ago, EPJ has provided a distinguished forum for publications in polymer research, including chemistry,

  2. Characterization of ethyl cellulose polymer.

    Science.gov (United States)

    Mahnaj, Tazin; Ahmed, Salah U; Plakogiannis, Fotios M

    2013-01-01

    Ethyl cellulose (EC) polymer was characterized for its property before considering the interactions with the plasicizer. Ethocel Std.10 FP Premium from Dow chemical company USA was tested for its solubility, morphology and thermal properties. Seven percentage of EC solution in ethanol was found to be the right viscosity used to prepare the film. The EC polymer and EC film without any plasticizers showed almost identical thermal behavior, but in X-ray diffraction showed different arrangements of crystallites and amorphous region. Dynamic mechanical analysis of film showed that without a plasticizer, EC film was not flexible and had very low elongation with high applied force. The aim of the work was to avoid using the commercially available EC dispersions Surelease® and Aquacoat®; both already have additives on it. Instead, Ethocel EC polymer (powder) was characterized in our laboratory in order to find out the properties of polymer before considering the interactions of the polymer with various plasticizers.

  3. Accelerated Characterization of Polymer Properties

    Energy Technology Data Exchange (ETDEWEB)

    R. Wroczynski; l. Brewer; D. Buckley; M. Burrell; R. Potyrailo

    2003-07-30

    This report describes the efforts to develop a suite of microanalysis techniques that can rapidly measure a variety of polymer properties of industrial importance, including thermal, photo-oxidative, and color stability; as well as ductility, viscosity, and mechanical and antistatic properties. Additional goals of the project were to direct the development of these techniques toward simultaneous measurements of multiple polymer samples of small size in real time using non-destructive and/or parallel or rapid sequential measurements, to develop microcompounding techniques for preparing polymers with additives, and to demonstrate that samples prepared in the microcompounder could be analyzed directly or used in rapid off-line measurements. These enabling technologies are the crucial precursors to the development of high-throughput screening (HTS) methodologies for the polymer additives industry whereby the rate of development of new additives and polymer formulations can be greatly accelerated.

  4. Direct Photopatterning of Electrochromic Polymers

    DEFF Research Database (Denmark)

    Jensen, Jacob; Dyer, Aubrey L.; Shen, D. Eric

    2013-01-01

    Propylenedioxythiophene (ProDOT) polymers are synthesized using an oxidative polymerization route that results in methacrylate substituted poly(ProDOTs) having a Mn of 10–20 kDa wherein the methacrylate functionality constitutes from 6 to 60% of the total monomer units. Solutions of these polymers...... show excellent film forming abilities, with thin films prepared using both spray‐casting and spin‐coating. These polymers are demonstrated to crosslink upon UV irradiation at 350 nm, in the presence of an appropriate photoinitiator, to render the films insoluble to common organic solvents....... Electrochemical, spectroelectrochemical, and colorimetric analyses of the crosslinked polymer films are performed to establish that they retain the same electrochromic qualities as the parent polymers with no detriment to the observed properties. To demonstrate applicability for multi‐film processing...

  5. Polymer research by neutron scattering

    International Nuclear Information System (INIS)

    Richter, D.

    1993-01-01

    Polymer physics aims on an understanding of the macroscopic behavior of polymer systems on the basis of their molecular structure and dynamics. For this purpose neutrons serve as a unique probe, allowing a simultaneous investigation of polymer structure and dynamics on a molecular scale. Furthermore, hydrogen deuterium exchange facilitates molecular labeling and offers the possibility to observe selected chains or chain parts in dense systems. Neutron small angle scattering reveals information on the conformation and possible aggregation of polymer chains. Data on linear and star like molecules are shown as examples. High resolution neutron spin-echospectroscopy observes the molecular dynamics of long chain molecules. Results on the large scale motion of chins in polymer melts are presented. finally, experiments on chain relaxation close to the glass transition are displayed. Three distinctly different relaxation processes are revealed. (author)

  6. Polymer materials for fusion reactors

    International Nuclear Information System (INIS)

    Yamaoka, H.

    1993-01-01

    The radiation-resistant polymer materials have recently drawn much attention from the viewpoint of components for fusion reactors. These are mainly applied to electrical insulators, thermal insulators and structural supports of superconducting magnets in fusion reactors. The polymer materials used for these purposes are required to withstand the synergetic effects of high mechanical loads, cryogenic temperatures and intense nuclear radiation. The objective of this review is to summarize the anticipated performance of candidate materials including polymer composites for fusion magnets. The cryogenic properties and the radiation effects of polymer materials are separately reviewed, because there is only limited investigation on the above-mentioned synergetic effects. Additional information on advanced polymer materials for fusion reactors is also introduced with emphasis on recent developments. (orig.)

  7. Ion beam modification of polymers

    International Nuclear Information System (INIS)

    Sofield, C.J.; Sugden, S.; Ing, J.; Bridwell, L.B.; Wang, Y.Q.

    1993-01-01

    The implantation of polymers has received considerable attention in recent years, primarily to examine doping of conducting polymers and to increase the surface conductivity (by many orders of magnitude) of highly insulating polymers. The interest in these studies was partly motivated by possible applications to microelectronic device fabrication. More recently it has been observed that ion implantation can under some conditions lead to the formation of a hard (e.g. as hard as steel, ca. 3 MPa) and conducting surface layer. This paper will review the ion beam modification of polymers resulting from ion implantation with reference to fundamental ion-solid interactions. This leads us to examine whether or not implantation of polymers is a contradiction in terms. (Author)

  8. Symposium cellular response to DNA damage the role of poly(ADP-ribose) poly(ADP-ribose) in the cellular response to DNA damage

    International Nuclear Information System (INIS)

    Berger, N.A.

    1985-01-01

    Poly(ADP-ribose) polymerase is a chromatin-bound enzyme which, on activation by DNA strand breaks, catalyzes the successive transfer of ADP-ribose units from NAD to nuclear proteins. Poly(ADP-ribose) synthesis is stimulated by DNA strand breaks, and the polymer may alter the structure and/or function of chromosomal proteins to facilitate the DNA repair process. Inhibitors of Poly(ADP-ribose) polymerase or deficiencies of the substrate, NAD, lead to retardation of the DNA repair process. When DNA strand breaks are extensive or when breaks fail to be repaired, the stimulus for activation of Poly(ADP-ribose) persists and the activated enzyme is capable of totaly consuming cellular pools of NAD. Depletion of NAD and consequent lowering of cellular ATP pools, due to activation of Poly(ADP-ribose) polymerase, may account for rapid cell death before DNA repair takes place and before the genetic effects of DNA damage become manifest

  9. Agarose gel electrophoresis for the separation of DNA fragments.

    Science.gov (United States)

    Lee, Pei Yun; Costumbrado, John; Hsu, Chih-Yuan; Kim, Yong Hoon

    2012-04-20

    Agarose gel electrophoresis is the most effective way of separating DNA fragments of varying sizes ranging from 100 bp to 25 kb(1). Agarose is isolated from the seaweed genera Gelidium and Gracilaria, and consists of repeated agarobiose (L- and D-galactose) subunits(2). During gelation, agarose polymers associate non-covalently and form a network of bundles whose pore sizes determine a gel's molecular sieving properties. The use of agarose gel electrophoresis revolutionized the separation of DNA. Prior to the adoption of agarose gels, DNA was primarily separated using sucrose density gradient centrifugation, which only provided an approximation of size. To separate DNA using agarose gel electrophoresis, the DNA is loaded into pre-cast wells in the gel and a current applied. The phosphate backbone of the DNA (and RNA) molecule is negatively charged, therefore when placed in an electric field, DNA fragments will migrate to the positively charged anode. Because DNA has a uniform mass/charge ratio, DNA molecules are separated by size within an agarose gel in a pattern such that the distance traveled is inversely proportional to the log of its molecular weight(3). The leading model for DNA movement through an agarose gel is "biased reptation", whereby the leading edge moves forward and pulls the rest of the molecule along(4). The rate of migration of a DNA molecule through a gel is determined by the following: 1) size of DNA molecule; 2) agarose concentration; 3) DNA conformation(5); 4) voltage applied, 5) presence of ethidium bromide, 6) type of agarose and 7) electrophoresis buffer. After separation, the DNA molecules can be visualized under uv light after staining with an appropriate dye. By following this protocol, students should be able to: Understand the mechanism by which DNA fragments are separated within a gel matrix Understand how conformation of the DNA molecule will determine its mobility through a gel matrix Identify an agarose solution of appropriate

  10. Ligation-based mutation detection and RCA in surface un-modified OSTE+ polymer microfluidic chambers

    DEFF Research Database (Denmark)

    Saharil, Farizah; Ahlford, Annika; Kuhnemund, Malte

    2013-01-01

    For the first time, we demonstrate DNA mutation detection in surface un-modified polymeric microfluidic chambers without suffering from bubble trapping or bubble formation. Microfluidic devices were manufactured in off-stoichiometry thiol-ene epoxy (OSTE+) polymer using an uncomplicated and rapid...... during bio-operation at elevated temperatures. In contrast, PMMA, PDMS and COP microfluidic devices required specific surface treatment....

  11. A Fast, Sensitive and Label Free Electrochemical DNA Sensor

    International Nuclear Information System (INIS)

    Chen Yu; Elling; Lee Yokeling; Chong Serchoong

    2006-01-01

    A label free and sensitive DNA/RNA silicon based electrochemical microsensor array was developed by using thin film of the conducting polymer polypyrrole doped with an oligonucleotide probe. The electrochemical potential pulse amperometry technique was used for a biowarfare pathogen target DNA detection. The electrical potential assistanted DNA hybridisation method was applied. The sensor signal was increased by increasing the electrical potential assistanted DNA hybridisation time. It was possible to detect 0.34pmol and 0.072fmol of complementary oligonucleotide target in 0.1ml in seconds by using unpolished and polished gold electrode respectively. The probe preparation was also in seconds time, comparing indirect electrochemical DNA sensor, it has a fast sensor preparation as well as sensor response and label free advantages. The silicon microfabrication technique was used for this sensor array fabrication, which holds the potential to integrate with sensor electrical circuits. The conducting polymer polypyrrole was electrochemically deposited on each electrode respectively which has a possibility to dope the different DNA probe into the individual electrode to form a sensor array

  12. Radiation-induced DNA breaks detected by immuno labelling of poly(ADP-ribose) in CHO cells. Standardization by pulsed-field gel electrophoresis

    International Nuclear Information System (INIS)

    Varlet, P.; Bidon, N.; Noel, G.; Averbeck, D.; Salamero, J.; DeMurcia, G.

    1998-01-01

    The poly (ADP-ribose) polymerase is an ubiquitous nuclear protein capable of binding specifically to DNA strand breaks. It synthesizes ADP-ribose polymers proportionally to DNA breaks. The actual method of reference to determine DNA double strand breaks is pulsed-field gel electrophoresis, but this requires many cells. It thus appeared of interest to use poly (ADP-ribos)ylation to follow and estimate γ-ray-induced DNA fragmentation at the level of isolated cells after γ-irradiation in chinese hamster ovary cells (CHO-K1). The results obtained by the immuno-labelling technique of ADP-ribose polymers were compared to those obtained by pulsed-field gel electrophoresis. They show that poly (ADP-ribos)ylation reflects the occurrence of radiation-induced DNA strand breaks. A clear relationship exists between the amount of ADP-ribose polymers detected and DNA double strand breaks after γ-irradiation. (authors)

  13. Polymers – A New Open Access Scientific Journal on Polymer Science

    Directory of Open Access Journals (Sweden)

    Shu-Kun Lin

    2009-12-01

    Full Text Available Polymers is a new interdisciplinary, Open Access scientific journal on polymer science, published by Molecular Diversity Preservation International (MDPI. This journal welcomes manuscript submissions on polymer chemistry, macromolecular chemistry, polymer physics, polymer characterization and all related topics. Both synthetic polymers and natural polymers, including biopolymers, are considered. Manuscripts will be thoroughly peer-reviewed in a timely fashion, and papers will be published, if accepted, within 6 to 8 weeks after submission. [...

  14. EDITORIAL: Electroactive polymer materials

    Science.gov (United States)

    Bar-Cohen, Yoseph; Kim, Kwang J.; Ryeol Choi, Hyouk; Madden, John D. W.

    2007-04-01

    Imitating nature's mechanisms offers enormous potential for the improvement of our lives and the tools we use. This field of the study and imitation of, and inspiration from, nature's methods, designs and processes is known as biomimetics. Artificial muscles, i.e. electroactive polymers (EAPs), are one of the emerging technologies enabling biomimetics. Polymers that can be stimulated to change shape or size have been known for many years. The activation mechanisms of such polymers include electrical, chemical, pneumatic, optical and magnetic. Electrical excitation is one of the most attractive stimulators able to produce elastic deformation in polymers. The convenience and practicality of electrical stimulation and the continual improvement in capabilities make EAP materials some of the most attractive among activatable polymers (Bar-Cohen Y (ed) 2004 Electroactive Polymer (EAP) Actuators as Artificial Muscles—Reality, Potential and Challenges 2nd edn, vol PM136 (Bellingham, WA: SPIE Press) pp 1-765). As polymers, EAP materials offer many appealing characteristics that include low weight, fracture tolerance and pliability. Furthermore, they can be configured into almost any conceivable shape and their properties can be tailored to suit a broad range of requirements. These capabilities and the significant change of shape or size under electrical stimulation while being able to endure many cycles of actuation are inspiring many potential possibilities for EAP materials among engineers and scientists in many different disciplines. Practitioners in biomimetics are particularly excited about these materials since they can be used to mimic the movements of animals and insects. Potentially, mechanisms actuated by EAPs will enable engineers to create devices previously imaginable only in science fiction. For many years EAP materials received relatively little attention due to their poor actuation capability and the small number of available materials. In the last fifteen

  15. SULFUR POLYMER ENCAPSULATION

    International Nuclear Information System (INIS)

    KALB, P.

    2001-01-01

    Sulfur polymer cement (SPC) is a thermoplastic polymer consisting of 95 wt% elemental sulfur and 5 wt% organic modifiers to enhance long-term durability. SPC was originally developed by the U.S. Bureau of Mines as an alternative to hydraulic cement for construction applications. Previous attempts to use elemental sulfur as a construction material in the chemical industry failed due to premature degradation. These failures were caused by the internal stresses that result from changes in crystalline structure upon cooling of the material. By reacting elemental sulfur with organic polymers, the Bureau of Mines developed a product that successfully suppresses the solid phase transition and significantly improves the stability of the product. SPC, originally named modified sulfur cement, is produced from readily available, inexpensive waste sulfur derived from desulfurization of both flue gases and petroleum. The commercial production of SPC is licensed in the United States by Martin Resources (Odessa, Texas) and is marketed under the trade name Chement 2000. It is sold in granular form and is relatively inexpensive ((approx)$0.10 to 0.12/lb). Application of SPC for the treatment of radioactive, hazardous, and mixed wastes was initially developed and patented by Brookhaven National Laboratory (BNL) in the mid-1980s (Kalb and Colombo, 1985; Colombo et al., 1997). The process was subsequently investigated by the Commission of the European Communities (Van Dalen and Rijpkema, 1989), Idaho National Engineering Laboratory (Darnell, 1991), and Oak Ridge National Laboratory (Mattus and Mattus, 1994). SPC has been used primarily in microencapsulation applications but can also be used for macroencapsulation of waste. SPC microencapsulation has been demonstrated to be an effective treatment for a wide variety of wastes, including incinerator hearth and fly ash; aqueous concentrates such as sulfates, borates, and chlorides; blowdown solutions; soils; and sludges. It is not

  16. Immobilization/hybridization of amino-modified DNA on plasma-polymerized allyl chloride

    International Nuclear Information System (INIS)

    Zhang Zhihong; Feng Chuanliang

    2007-01-01

    The present work describes the fabrication and characterization of chloride-derivatized polymer coatings prepared by continuous wave (cw) plasma polymerization as adhesion layers in DNA immobilization/hybridization. The stability of plasma-polymerized allyl chloride (ppAC) in H 2 O was characterized by variation of the thickness of polymer films and its wettability was examined by water contact angle technique. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to study polymer matrix properties and oligonucleotide/DNA binding interaction. With the same carrier gas rate and process pressure, plasma polymers deposited at different input powers show various comparable immobilization properties; nevertheless, low input power plasma-polymerized films gives a lower sensitivity toward DNA binding than that from high input power plasma-deposited films. The following DNA immobilization on chloride-functionalized surfaces was found dependence on the macromolecular architecture of the plasma films. The hybridization between probe DNA and total mismatch target DNA shows no non-specific adsorption between target and ppAC

  17. Physical Properties of Polymers (Ultrastructure Processing of Polymers)

    Science.gov (United States)

    1982-09-30

    vinyl benzene Network-Diluent Systems". 17. J . Appl. Polym. Sci. 28, 219-224 (1983) (with R. Vukovic and W.J. MacKnight) "Compatibility of Some...Temperature of Polymer Networks by Dil uents". 23. J . Appl. Polym. Sci. 28, 1379-1389 (1983) (with R. Vukovic , V. Kuresevic, N. Segudovic, and W.J...AFOSR 80-0101 IV. DATES: 1 January 1980 - 30 September 1982 V. SENIOR RESEARCH PERSONNEL*: Dr. C. Crosby Dr. G. ten Brinke Dr. T. Ellis Dr. R. Vukovic

  18. Conjugated polymer zwitterions and solar cells comprising conjugated polymer zwitterions

    Science.gov (United States)

    Emrick, Todd; Russell, Thomas; Page, Zachariah; Liu, Yao

    2018-06-05

    A conjugated polymer zwitterion includes repeating units having structure (I), (II), or a combination thereof ##STR00001## wherein Ar is independently at each occurrence a divalent substituted or unsubstituted C3-30 arylene or heteroarylene group; L is independently at each occurrence a divalent C1-16 alkylene group, C6-30arylene or heteroarylene group, or alkylene oxide group; and R1 is independently at each occurrence a zwitterion. A polymer solar cell including the conjugated polymer zwitterion is also disclosed.

  19. Protein Polymers and Amyloids

    DEFF Research Database (Denmark)

    Risør, Michael Wulff

    2014-01-01

    Several human disorders are caused by a common general disease mechanism arising from abnormal folding and aggregation of the underlying protein. These include the prevalent dementias like Alzheimer’s and Parkinson’s, where accumulation of protein fibrillar structures, known as amyloid fibrils......, is a general hallmark. They also include the α1-antitrypsin deficiency, where disease-causing mutations in the serine protease inhibitor, α1-antitrypsin (α1AT), leads to accumulation of the aberrant protein in the liver of these patients. The native metastable structure of α1AT constitutes a molecular trap...... that inhibits its target protease through a large conformational change but mutations compromise this function and cause premature structural collapse into hyperstable polymers. Understanding the conformational disorders at a molecular level is not only important for our general knowledge on protein folding...

  20. Sodium conducting polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Skaarup, S.; West, K. (eds.)

    1989-04-01

    This section deals with the aspects of ionic conduction in general as well as specific experimental results obtained for sodium systems. The conductivity as a function of temperature and oxygen/metal ratio are given for the systems NaI, NaCF/sub 3/SO/sub 3/ and NaClO/sub 4/ plus polyethylene oxide. Attempts have been made to produce mixed phase solid electrolytes analogous to the lithium systems that have worked well. These consist of mixtures of polymer and a solid electrolyte. The addition of both nasicon and sodium beta alumina unexpectedly decreases the ionic conductivity in contrast to the lithium systems. Addition of the nonconducting silica AEROSIL in order to increase the internal surface area has the effect of retarding the phase transition at 60 deg. C, but does not enhance the conductivity. (author) 23 refs.

  1. Conducting Polymer Based Nanobiosensors

    Directory of Open Access Journals (Sweden)

    Chul Soon Park

    2016-06-01

    Full Text Available In recent years, conducting polymer (CP nanomaterials have been used in a variety of fields, such as in energy, environmental, and biomedical applications, owing to their outstanding chemical and physical properties compared to conventional metal materials. In particular, nanobiosensors based on CP nanomaterials exhibit excellent performance sensing target molecules. The performance of CP nanobiosensors varies based on their size, shape, conductivity, and morphology, among other characteristics. Therefore, in this review, we provide an overview of the techniques commonly used to fabricate novel CP nanomaterials and their biosensor applications, including aptasensors, field-effect transistor (FET biosensors, human sense mimicking biosensors, and immunoassays. We also discuss prospects for state-of-the-art nanobiosensors using CP nanomaterials by focusing on strategies to overcome the current limitations.

  2. Photorefractivity of triphenylamine polymers

    Science.gov (United States)

    Tsujimura, S.; Kinashi, K.; Sakai, W.; Tsutsumi, N.

    2012-10-01

    We present here the enhanced photorefractive performance and dynamic holographic image of poly(4-diphenylamino)styrene (PDAS)-based photorefractive polymeric composites (PPCs). PDAS and FDCST were synthesized as a photoconductive polymer and a nonlinear optical (NLO) dye, respectively. PPC films including PDAS, TPA (or ECZ), FDCST, and PCBM were investigated. The photorefractive quantities of the PDAS-based PPCs were measured by a degenerate four-wave mixing (DFWM) technique. Additionally, the dynamic holographic images were recorded through an appropriate PDAS-based PPC. Those dynamic holographic images clearly duplicate the original motion with high-speed quality. The present approach provides a promising candidate for the future application of dynamic holographic displays.

  3. Self-healing polymers

    Science.gov (United States)

    Klein, Daniel J. (Inventor)

    2011-01-01

    A three dimensional structure fabricated from a self-healing polymeric material, comprising poly(ester amides) obtained from ethylene glycol, azelaic acid and 1,1-aminoundecanoic acid, wherein polymeric material has a melt index above 2.5 g/10 min. as determined by ASTM D1238 at 190.degree. C. and 2.16kg, impact resistance and ductility sufficient to resist cracking and brittle fracture upon impact by a 9 mm bullet fired at a temperature of about 29.degree. C. at subsonic speed in a range from about 800 feet/sec to about 1000 feet/sec. It has been determined that the important factors necessary for self-healing behavior of polymers include sufficient impact strength, control of the degree of crystallinity, low melting point and the ability to instantly melt at impacted area.

  4. The Extraction and Partial Purification of Bacterial DNA as a Practical Exercise for GCE Advanced Level Students.

    Science.gov (United States)

    Falconer, A. C.; Hayes, L. J.

    1986-01-01

    Describes a relatively simple method of extraction and purification of bacterial DNA. This technique permits advanced secondary-level science students to obtain adequate amounts of DNA from very small pellets of bacteria and to observe some of its polymer properties. (ML)

  5. Electrochromic in conjugated polymers

    International Nuclear Information System (INIS)

    Picado Valenzuela, Alfredo

    2007-01-01

    This revision considered object the description of one of the materials with the greatest potential in the field of electrochromic (mainly in the visible region): the conjugated polymers (CP), area of enormous potential both now and in a short time ahead. The CP are insulating materials and organic semiconductors in a state not doped. They can be doped positively or negatively being observed a significant increase in the conductivity and being generated a color change in these materials. The understanding of how optical properties vary based on the chemical structure of the polymer or its mixtures and more precisely of the alternatives that can be entered into the conjugated system or π system to obtain a material that besides to be flexible, environmentally stable, presents the colored states. The revision was centred chiefly in the polypyrrole (Ppy), the polythiophene (PTh) and their derivatives such as poly (3.4-ethylenedioxythiophene) (PEDOT). The advantage of using monomers with variable structure, to adjust the composition of the copolymer, or to blend with the PC, allows to obtain a variety of colored states that can be modulated through the visible spectrum and even with applications to wavelengths outside of this region. Because the PC presented at least two different colored states can be varied continuously as a function of the voltage applied. In some cases, they may submit multicoloured statements, which offers a range of possibilities for their application in flexible electronic devices type screens and windows. Applications include smart windows, camouflage clothing and data screens. This type of material is emerging as one of the substitutes of the traditional inorganic semiconductor, with the advantage of its low cost, high flexibility and the possibility to generate multiple colors through the handling of the monomers in the structure and control of energy of his band gap. (author) [es

  6. Monitoring of polymer melt processing

    International Nuclear Information System (INIS)

    Alig, Ingo; Steinhoff, Bernd; Lellinger, Dirk

    2010-01-01

    The paper reviews the state-of-the-art of in-line and on-line monitoring during polymer melt processing by compounding, extrusion and injection moulding. Different spectroscopic and scattering techniques as well as conductivity and viscosity measurements are reviewed and compared concerning their potential for different process applications. In addition to information on chemical composition and state of the process, the in situ detection of morphology, which is of specific interest for multiphase polymer systems such as polymer composites and polymer blends, is described in detail. For these systems, the product properties strongly depend on the phase or filler morphology created during processing. Examples for optical (UV/vis, NIR) and ultrasonic attenuation spectra recorded during extrusion are given, which were found to be sensitive to the chemical composition as well as to size and degree of dispersion of micro or nanofillers in the polymer matrix. By small-angle light scattering experiments, process-induced structures were detected in blends of incompatible polymers during compounding. Using conductivity measurements during extrusion, the influence of processing conditions on the electrical conductivity of polymer melts with conductive fillers (carbon black or carbon nanotubes) was monitored. (topical review)

  7. DNA preservation in silk.

    Science.gov (United States)

    Liu, Yawen; Zheng, Zhaozhu; Gong, He; Liu, Meng; Guo, Shaozhe; Li, Gang; Wang, Xiaoqin; Kaplan, David L

    2017-06-27

    The structure of DNA is susceptible to alterations at high temperature and on changing pH, irradiation and exposure to DNase. Options to protect and preserve DNA during storage are important for applications in genetic diagnosis, identity authentication, drug development and bioresearch. In the present study, the stability of total DNA purified from human dermal fibroblast cells, as well as that of plasmid DNA, was studied in silk protein materials. The DNA/silk mixtures were stabilized on filter paper (silk/DNA + filter) or filter paper pre-coated with silk and treated with methanol (silk/DNA + PT-filter) as a route to practical utility. After air-drying and water extraction, 50-70% of the DNA and silk could be retrieved and showed a single band on electrophoretic gels. 6% silk/DNA + PT-filter samples provided improved stability in comparison with 3% silk/DNA + filter samples and DNA + filter samples for DNA preservation, with ∼40% of the band intensity remaining at 37 °C after 40 days and ∼10% after exposure to UV light for 10 hours. Quantitative analysis using the PicoGreen assay confirmed the results. The use of Tris/borate/EDTA (TBE) buffer enhanced the preservation and/or extraction of the DNA. The DNA extracted after storage maintained integrity and function based on serving as a functional template for PCR amplification of the gene for zinc finger protein 750 (ZNF750) and for transgene expression of red fluorescence protein (dsRed) in HEK293 cells. The high molecular weight and high content of a crystalline beta-sheet structure formed on the coated surfaces likely accounted for the preservation effects observed for the silk/DNA + PT-filter samples. Although similar preservation effects were also obtained for lyophilized silk/DNA samples, the rapid and simple processing available with the silk-DNA-filter membrane system makes it appealing for future applications.

  8. Force induced DNA melting

    International Nuclear Information System (INIS)

    Santosh, Mogurampelly; Maiti, Prabal K

    2009-01-01

    When pulled along the axis, double-strand DNA undergoes a large conformational change and elongates by roughly twice its initial contour length at a pulling force of about 70 pN. The transition to this highly overstretched form of DNA is very cooperative. Applying a force perpendicular to the DNA axis (unzipping), double-strand DNA can also be separated into two single-stranded DNA, this being a fundamental process in DNA replication. We study the DNA overstretching and unzipping transition using fully atomistic molecular dynamics (MD) simulations and argue that the conformational changes of double-strand DNA associated with either of the above mentioned processes can be viewed as force induced DNA melting. As the force at one end of the DNA is increased the DNA starts melting abruptly/smoothly above a critical force depending on the pulling direction. The critical force f m , at which DNA melts completely decreases as the temperature of the system is increased. The melting force in the case of unzipping is smaller compared to the melting force when the DNA is pulled along the helical axis. In the case of melting through unzipping, the double-strand separation has jumps which correspond to the different energy minima arising due to sequence of different base pairs. The fraction of Watson-Crick base pair hydrogen bond breaking as a function of force does not show smooth and continuous behavior and consists of plateaus followed by sharp jumps.

  9. DNA damage and autophagy

    International Nuclear Information System (INIS)

    Rodriguez-Rocha, Humberto; Garcia-Garcia, Aracely; Panayiotidis, Mihalis I.; Franco, Rodrigo

    2011-01-01

    Both exogenous and endogenous agents are a threat to DNA integrity. Exogenous environmental agents such as ultraviolet (UV) and ionizing radiation, genotoxic chemicals and endogenous byproducts of metabolism including reactive oxygen species can cause alterations in DNA structure (DNA damage). Unrepaired DNA damage has been linked to a variety of human disorders including cancer and neurodegenerative disease. Thus, efficient mechanisms to detect DNA lesions, signal their presence and promote their repair have been evolved in cells. If DNA is effectively repaired, DNA damage response is inactivated and normal cell functioning resumes. In contrast, when DNA lesions cannot be removed, chronic DNA damage triggers specific cell responses such as cell death and senescence. Recently, DNA damage has been shown to induce autophagy, a cellular catabolic process that maintains a balance between synthesis, degradation, and recycling of cellular components. But the exact mechanisms by which DNA damage triggers autophagy are unclear. More importantly, the role of autophagy in the DNA damage response and cellular fate is unknown. In this review we analyze evidence that supports a role for autophagy as an integral part of the DNA damage response.

  10. A Cationic Smart Copolymer for DNA Binding

    Directory of Open Access Journals (Sweden)

    Tânia Ribeiro

    2017-11-01

    Full Text Available A new block copolymer with a temperature-responsive block and a cationic block was prepared by reversible addition-fragmentation chain transfer (RAFT polymerization, with good control of its size and composition. The first block is composed by di(ethylene glycol methyl ether methacrylate (DEGMA and oligo(ethylene glycol methyl ether methacrylate (OEGMA, with the ratio DEGMA/OEGMA being used to choose the volume phase transition temperature of the polymer in water, tunable from ca. 25 to above 90 °C. The second block, of trimethyl-2-methacroyloxyethylammonium chloride (TMEC, is positively charged at physiological pH values and is used for DNA binding. The coacervate complexes between the block copolymer and a model single strand DNA are characterized by fluorescence correlation spectroscopy and fluorescence spectroscopy. The new materials offer good prospects for biomedical application, for example in controlled gene delivery.

  11. DNA Open states and DNA hydratation

    International Nuclear Information System (INIS)

    Lema-Larre, B. de; Martin-Landrove, M

    1995-01-01

    It is a very well-known fact that an protonic exchange exists among natural DNA filaments and synthetic polynucleotides with the solvent (1--2). The existence of DNA open states, that is to say states for which the interior of the DNA molecule is exposed to the external environment, it has been demonstrated by means of proton-deuterium exchange (3). This work has carried out experiments measuring the dispersion of the traverse relaxation rate (4), as a pulsation rate function in a Carr-Purcell-Meiboom-Gill (CPMG) pulses sequence rate, to determine changes in the moist layer of the DNA molecule. The experiments were carried out under different experimental conditions in order to vary the probability that open states occurs, such as temperature or the exposure to electromagnetic fields. Some theoretical models were supposed to adjust the experimental results including those related to DNA non linear dynamic [es

  12. Thermoresponsive Polymers for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Theoni K. Georgiou

    2011-08-01

    Full Text Available Thermoresponsive polymers are a class of “smart” materials that have the ability to respond to a change in temperature; a property that makes them useful materials in a wide range of applications and consequently attracts much scientific interest. This review focuses mainly on the studies published over the last 10 years on the synthesis and use of thermoresponsive polymers for biomedical applications including drug delivery, tissue engineering and gene delivery. A summary of the main applications is given following the different studies on thermoresponsive polymers which are categorized based on their 3-dimensional structure; hydrogels, interpenetrating networks, micelles, crosslinked micelles, polymersomes, films and particles.

  13. Physics of photorefraction in polymers

    CERN Document Server

    West, Dave

    2004-01-01

    Photorefractive polymer composites are an unusually sensitive class of photopolymers. Physics of Photorefraction in Polymers describes our current understanding of the physical processes that produce a photorefractive effect in key composite materials. Topics as diverse as charge generation, dispersive charge transport, charge compensation and trapping, molecular diffusion, organic composite structure, and nonlinear optical wave coupling are all developed from a physical perspective. Emphasis is placed on explaining how these physical processes lead to observable properties of the polymers, and the authors discuss various applications, including holographic archiving.

  14. Multilayer Electroactive Polymer Composite Material

    Science.gov (United States)

    Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Park, Cheol (Inventor); Draughon, Gregory K. (Inventor); Ounaies, Zoubeida (Inventor)

    2011-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  15. Polymer liquids fracture like solids

    DEFF Research Database (Denmark)

    Huang, Qian; Hassager, Ole

    2017-01-01

    While fracture in brittle solids has been studied for centuries until today, there are few studies on fracture in polymer liquids. Recent developments in experimental techniques, especially the combination of controlled filament stretching rheometry and high speed imaging, have opened new windows...... into the detailed study of fracture processes for polymer liquids. High speed imaging shows that polymer liquids fracture like solids with initiation and propagation of an edge fracture. However, remarkable features such as highly reproducible critical stress, independent appearance of multiple fractures...

  16. Bridging scales in polymer physics and processing

    NARCIS (Netherlands)

    Hütter, M.; Kröger, M.; Öttinger, H.C.; Schweizer, T.

    2001-01-01

    Understanding both the flow behavior of polymers during processing and the end-use properties offinished plastic products from a molecular picture of the constituent polymers has been a long-standing dreamin polymer engineering and science. It is the goal of our work in the Polymer Physics Group to

  17. Statistical thermodynamics of equilibrium polymers at interfaces

    NARCIS (Netherlands)

    Gucht, van der J.; Besseling, N.A.M.

    2002-01-01

    The behavior of a solution of equilibrium polymers (or living polymers) at an interface is studied, using a Bethe-Guggenheim lattice model for molecules with orientation dependent interactions. The density profile of polymers and the chain length distribution are calculated. For equilibrium polymers

  18. A simple approach for producing highly efficient DNA carriers with reduced toxicity based on modified polyallylamine

    Energy Technology Data Exchange (ETDEWEB)

    Oskuee, Reza Kazemi [Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Department of Medical Biotechnology, School of Medicine, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Dosti, Fatemeh [School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Gholami, Leila [Targeted Drug Delivery Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Malaekeh-Nikouei, Bizhan, E-mail: malaekehb@mums.ac.ir [Nanotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of)

    2015-04-01

    Nowadays gene delivery is a topic in many research studies. Non-viral vectors have many advantages over viral vectors in terms of safety, immunogenicity and gene carrying capacity but they suffer from low transfection efficiency and high toxicity. In this study, polyallylamine (PAA), the cationic polymer, has been modified with hydrophobic branches to increase the transfection efficiency of the polymer. Polyallylamine with molecular weights of 15 and 65 kDa was selected and grafted with butyl, hexyl and decyl acrylate at percentages of 10, 30 and 50. The ability of the modified polymer to condense DNA was examined by ethidium bromide test. The complex of modified polymer and DNA (polyplex) was characterized for size, zeta potential, transfection efficiency and cytotoxicity in Neuro2A cell lines. The results of ethidium bromide test showed that grafting of PAA decreased its ability for DNA condensation but vectors could still condense DNA at moderate and high carrier to DNA ratios. Most of polyplexes had particle size between 150 and 250 nm. The prepared vectors mainly showed positive zeta potential but carriers composed of PAA with high percentage of grafting had negative zeta potential. The best transfection activity was observed in vectors with hexyl acrylate chain. Grafting of polymer reduced its cytotoxicity especially at percentages of 30 and 50. The vectors based of PAA 15 kDa had better transfection efficiency than the vectors made of PAA 65 kDa. In conclusion, results of the present study indicated that grafting PAA 15 kDa with high percentages of hexyl acrylate can help to prepare vectors with better transfection efficiency and less cytotoxicity. - Highlights: • The modified polyallylamine was synthesized as a gene carrier. • Modification of polyallylamine (15 kDa) with high percentages of hexyl acrylate improved transfection activity remarkably. • Grafting of polymer with acrylate derivatives reduced polymer cytotoxicity especially at percentages of

  19. Performance limitations of polymer electrolytes based on ethylene oxide polymers

    International Nuclear Information System (INIS)

    Buriez, Olivier; Han, Yong Bong; Hou, Jun; Kerr, John B.; Qiao, Jun; Sloop, Steven E.; Tian, Minmin; Wang, Shanger

    1999-01-01

    Studies of polymer electrolyte solutions for lithium-polymer batteries are described. Two different salts, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium trifluoromethanesulfonate (LiTf), were dissolved in a variety of polymers. The structures were all based upon the ethylene oxide unit for lithium ion solvation and both linear and comb-branch polymer architectures have been examined. Conductivity, salt diffusion coefficient and transference number measurements demonstrate the superior transport properties of the LiTFSI salt over LiTf. Data obtained on all of these polymers combined with LiTFSI salts suggest that there is a limit to the conductivity achievable at room temperature, at least for hosts containing ethylene oxide units. The apparent conductivity limit is 5 x 10-5 S/cm at 25 C. Providing that the polymer chain segment containing the ethylene oxide units is at least 5-6 units long there appears to be little influence of the polymer framework to which the solvating groups are attached. To provide adequate separator function, the mechanical properties may be disconnected from the transport properties by selection of an appropriate architecture combined with an adequately long ethylene oxide chain. For both bulk and interfacial transport of the lithium ions, conductivity data alone is insufficient to understand the processes that occur. Lithium ion transference numbers and salt diffusion coefficients also play a major role in the observed behavior and the transport properties of these polymer electrolyte solutions appear to be quite inadequate for ambient temperature performance. At present, this restricts the use of such systems to high temperature applications. Several suggestions are given to overcome these obstacles

  20. Immunoassay of DNA damage

    International Nuclear Information System (INIS)

    Gasparro, F.P.; Santella, R.M.

    1988-01-01

    The direct photomodification of DNA by ultraviolet light or the photo-induced addition of exogenous compounds to DNA components results in alterations of DNA structure ranging from subtle to profound. There are two consequences of these conformational changes. First, cells in which the DNA has been damaged are capable of executing repair steps. Second, the DNA which is usually of very low immunogenicity now becomes highly antigenic. This latter property has allowed the production of a series of monoclonal antibodies that recognize photo-induced DNA damage. Monoclonal antibodies have been generated that recognize the 4',5'-monoadduct and the crosslink of 8-methoxypsoralen in DNA. In addition, another antibody has been prepared which recognizes the furan-side monoadduct of 6,4,4'-trimethylangelicin in DNA. These monoclonal antibodies have been characterized as to sensitivity and specificity using non-competitive and competitive enzyme-linked-immunosorbent assays (ELISA). (author)

  1. Immunoassay of DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    Gasparro, F P; Santella, R M

    1988-09-01

    The direct photomodification of DNA by ultraviolet light or the photo-induced addition of exogenous compounds to DNA components results in alterations of DNA structure ranging from subtle to profound. There are two consequences of these conformational changes. First, cells in which the DNA has been damaged are capable of executing repair steps. Second, the DNA which is usually of very low immunogenicity now becomes highly antigenic. This latter property has allowed the production of a series of monoclonal antibodies that recognize photo-induced DNA damage. Monoclonal antibodies have been generated that recognize the 4',5'-monoadduct and the crosslink of 8-methoxypsoralen in DNA. In addition, another antibody has been prepared which recognizes the furan-side monoadduct of 6,4,4'-trimethylangelicin in DNA. These monoclonal antibodies have been characterized as to sensitivity and specificity using non-competitive and competitive enzyme-linked-immunosorbent assays (ELISA).

  2. DNA computing models

    CERN Document Server

    Ignatova, Zoya; Zimmermann, Karl-Heinz

    2008-01-01

    In this excellent text, the reader is given a comprehensive introduction to the field of DNA computing. The book emphasizes computational methods to tackle central problems of DNA computing, such as controlling living cells, building patterns, and generating nanomachines.

  3. DNA tagged microparticles

    Science.gov (United States)

    Farquar, George Roy; Leif, Roald N; Wheeler, Elizabeth

    2015-05-05

    A simulant that includes a carrier and DNA encapsulated in the carrier. Also a method of making a simulant including the steps of providing a carrier and encapsulating DNA in the carrier to produce the simulant.

  4. Modeling DNA Replication.

    Science.gov (United States)

    Bennett, Joan

    1998-01-01

    Recommends the use of a model of DNA made out of Velcro to help students visualize the steps of DNA replication. Includes a materials list, construction directions, and details of the demonstration using the model parts. (DDR)

  5. Water Soluble Polymers for Pharmaceutical Applications

    Directory of Open Access Journals (Sweden)

    Veeran Gowda Kadajji

    2011-11-01

    Full Text Available Advances in polymer science have led to the development of novel drug delivery systems. Some polymers are obtained from natural resources and then chemically modified for various applications, while others are chemically synthesized and used. A large number of natural and synthetic polymers are available. In the present paper, only water soluble polymers are described. They have been explained in two categories (1 synthetic and (2 natural. Drug polymer conjugates, block copolymers, hydrogels and other water soluble drug polymer complexes have also been explained. The general properties and applications of different water soluble polymers in the formulation of different dosage forms, novel delivery systems and biomedical applications will be discussed.

  6. Electrostatics of polymer translocation events in electrolyte solutions.

    Science.gov (United States)

    Buyukdagli, Sahin; Ala-Nissila, T

    2016-07-07

    We develop an analytical theory that accounts for the image and surface charge interactions between a charged dielectric membrane and a DNA molecule translocating through the membrane. Translocation events through neutral carbon-based membranes are driven by a competition between the repulsive DNA-image-charge interactions and the attractive coupling between the DNA segments on the trans and the cis sides of the membrane. The latter effect is induced by the reduction of the coupling by the dielectric membrane. In strong salt solutions where the repulsive image-charge effects dominate the attractive trans-cis coupling, the DNA molecule encounters a translocation barrier of ≈10 kBT. In dilute electrolytes, the trans-cis coupling takes over image-charge forces and the membrane becomes a metastable attraction point that can trap translocating polymers over long time intervals. This mechanism can be used in translocation experiments in order to control DNA motion by tuning the salt concentration of the solution.

  7. Polymer and Polymer Gel of Liquid Crystalline Semiconductors

    Institute of Scientific and Technical Information of China (English)

    Teppei Shimakawa; Naoki Yoshimoto; Jun-ichi Hanna

    2004-01-01

    It prepared a polymer and polymer gel of a liquid crystalline (LC) semiconductor having a 2-phenylnaphthalene moiety and studied their charge carrier transport properties by the time-of-flight technique. It is found that polyacrylate having the mesogenic core moiety of 2-phenylnaphtalene (PNP-acrylate) exhibited a comparable mobility of 10-4cm2/Vs in smectic A phase to those in smectic A (SmA) phase of small molecular liquid crystals with the same core moiety, e.g., 6-(4'-octylphenyl)- 2-dodecyloxynaphthalene (8-PNP-O12), and an enhanced mobility up to 10-3cm2/Vs in the LC-glassy phase at room temperature, when mixed with a small amount of 8-PNP-O12. On the other hand, the polymer gel consisting of 20 wt %-hexamethylenediacrylate (HDA)-based cross-linked polymer and 8-PNP-O12 exhibited no degraded mobility when cross-linked at the mesophase. These results indicate that the polymer and polymer composite of liquid crystalline semiconductors provide us with an easy way to realize a quality organic semiconductor thin film for the immediate device applications.

  8. New developments in thermally stable polymers

    Science.gov (United States)

    Hergenrother, Paul M.

    1991-01-01

    Advances in high-temperature polymers since 1985 are discussed with the emphasis on the chemistry. High-temperature polymers refer to materials that exhibit glass-transition temperatures greater than 200 C and have the chemical structure expected to provide high thermooxidative stability. Specific polymers or series of polymers were selected to show how the chemical structure influences certain properties. Poly(arylene ethers) and polyimides are the two principal families of polymers discussed. Recent work on poly(arylene ethers) has concentrated on incorporating heterocyclic units within the polymer backbone. Recent polyimide work has centered on the synthesis of new polymers from novel monomers, several containing the trifluoromethyl group strategically located on the molecule. Various members in each of these polymer families display a unique combination of properties, heretofore unattainable. Other families of polymers are also briefly discussed with a polymer from an AB maleimidobenzocyclobutene exhibiting an especially attractive combination of properties.

  9. A colorimetric platform for sensitively differentiating telomere DNA with different lengths, monitoring G-quadruplex and dsDNA based on silver nanoclusters and unmodified gold nanoparticles

    Science.gov (United States)

    Qu, Fei; Chen, Zeqiu; You, Jinmao; Song, Cuihua

    2018-05-01

    Human telomere DNA plays a vital role in genome integrity control and carcinogenesis as an indication for extensive cell proliferation. Herein, silver nanoclusters (Ag NCs) templated by polymer and unmodified gold nanoparticles (Au NPs) are designed as a new colorimetric platform for sensitively differentiating telomere DNA with different lengths, monitoring G-quadruplex and dsDNA. Ag NCs can produce the aggregation of Au NPs, so the color of Au NPs changes to blue and the absorption peak moves to 700 nm. While the telomere DNA can protect Au NPs from aggregation, the color turns to red again and the absorption band blue shift. Benefiting from the obvious color change, we can differentiate the length of telomere DNA by naked eyes. As the length of telomere DNA is longer, the variation of color becomes more noticeable. The detection limits of telomere DNA containing 10, 22, 40, 64 bases are estimated to be 1.41, 1.21, 0.23 and 0.22 nM, respectively. On the other hand, when telomere DNA forms G-quadruplex in the presence of K+, or dsDNA with complementary sequence, both G-quadruplex and dsDNA can protect Au NPs better than the unfolded telomere DNA. Hence, a new colorimetric platform for monitoring structure conversion of DNA is established by Ag NCs-Au NPs system, and to prove this type of application, a selective K+ sensor is developed.

  10. Approaches for Making High Performance Polymer Materials from Commodity Polymers

    Institute of Scientific and Technical Information of China (English)

    Xu Xi

    2004-01-01

    A brief surrey of ongoing research work done for improving and enhancing the properties of commodity polymers by the author and author's colleagues is given in this paper. A series of high performance polymers and polymer nanomaterials were successfully prepared through irradiation and stress-induced reactions of polymers and hydrogen bonding. The methods proposed are viable, easy in operation, clean and efficient.1. The effect of irradiation source (UV light, electron beam, γ -ray and microwave), irradiation dose, irradiation time and atmosphere etc. on molecular structure of polyolefine during irradiation was studied. The basic rules of dominating oxidation, degradation and cross-linking reactions were mastered. Under the controlled conditions, cross-linking reactions are prevented, some oxygen containing groups are introduced on the molecular chain of polyolefine to facilitate the interface compatibility of their blends. A series of high performance polymer materials: u-HDPE/PA6,u-HDPE/CaCO3, u-iPP/STC, γ-HDPE/STC, γ-LLDPE/ATH, e-HDPE, e-LLDPE and m-HDPEfilled system were prepared (u- ultraviolet light irradiated, γ- γ-ray irradiated, e- electron beam irradiated, m- microwave irradiated)2. The effect of ultrasonic irradiation, jet and pan-milling on structure and changes in properties of polymers were studied. Imposition of critical stress on polymer chain can cause the scission of bonds to form macroradicals. The macroradicals formed in this way may recombine or react with monomer or other radicals to form linear, branched or cross-linked polymers or copolymers. About 20 kinds of block/graft copolymers have been synthesized from polymer-polymer or polymer-monomer through ultrasonic irradiation.Through jet-milling, the molecular weight of PVC is decreased somewhat, the intensity of its crystalline absorption bonds becomes indistinct. The processability, the yield strength, strength at break and elongation at break of PVC get increased quite a lot after

  11. DNA: Structure and function

    DEFF Research Database (Denmark)

    Sinden, Richard R.; E. Pearson, Christopher; N. Potaman, Vladimir

    1998-01-01

    This chapter discusses the structure and function of DNA. DNA occupies a critical role in cells, because it is the source of all intrinsic genetic information. Chemically, DNA is a very stable molecule, a characteristic important for a macromolecule that may have to persist in an intact form...

  12. Replicating animal mitochondrial DNA

    Directory of Open Access Journals (Sweden)

    Emily A. McKinney

    2013-01-01

    Full Text Available The field of mitochondrial DNA (mtDNA replication has been experiencing incredible progress in recent years, and yet little is certain about the mechanism(s used by animal cells to replicate this plasmid-like genome. The long-standing strand-displacement model of mammalian mtDNA replication (for which single-stranded DNA intermediates are a hallmark has been intensively challenged by a new set of data, which suggests that replication proceeds via coupled leading-and lagging-strand synthesis (resembling bacterial genome replication and/or via long stretches of RNA intermediates laid on the mtDNA lagging-strand (the so called RITOLS. The set of proteins required for mtDNA replication is small and includes the catalytic and accessory subunits of DNA polymerase y, the mtDNA helicase Twinkle, the mitochondrial single-stranded DNA-binding protein, and the mitochondrial RNA polymerase (which most likely functions as the mtDNA primase. Mutations in the genes coding for the first three proteins are associated with human diseases and premature aging, justifying the research interest in the genetic, biochemical and structural properties of the mtDNA replication machinery. Here we summarize these properties and discuss the current models of mtDNA replication in animal cells.

  13. Recent advances in photorefractive polymers

    Science.gov (United States)

    Thomas, Jayan; Christenson, C. W.; Lynn, B.; Blanche, P.-A.; Voorakaranam, R.; Norwood, R. A.; Yamamoto, M.; Peyghambarian, N.

    2011-10-01

    Photorefractive composites derived from conducting polymers offer the advantage of dynamically recording holograms without the need for processing of any kind. Thus, they are the material of choice for many cutting edge applications, such as updatable three-dimensional (3D) displays and 3D telepresence. Using photorefractive polymers, 3D images or holograms can be seen with the unassisted eye and are very similar to how humans see the actual environment surrounding them. Absence of a large-area and dynamically updatable holographic recording medium has prevented realization of the concept. The development of a novel nonlinear optical chromophore doped photoconductive polymer composite as the recording medium for a refreshable holographic display is discussed. Further improvements in the polymer composites could bring applications in telemedicine, advertising, updatable 3D maps and entertainment.

  14. Layered plasma polymer composite membranes

    Science.gov (United States)

    Babcock, Walter C.

    1994-01-01

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

  15. Polymer electronic devices and materials.

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, William Kent; Baca, Paul Martin; Dirk, Shawn M.; Anderson, G. Ronald; Wheeler, David Roger

    2006-01-01

    Polymer electronic devices and materials have vast potential for future microsystems and could have many advantages over conventional inorganic semiconductor based systems, including ease of manufacturing, cost, weight, flexibility, and the ability to integrate a wide variety of functions on a single platform. Starting materials and substrates are relatively inexpensive and amenable to mass manufacturing methods. This project attempted to plant the seeds for a new core competency in polymer electronics at Sandia National Laboratories. As part of this effort a wide variety of polymer components and devices, ranging from simple resistors to infrared sensitive devices, were fabricated and characterized. Ink jet printing capabilities were established. In addition to promising results on prototype devices the project highlighted the directions where future investments must be made to establish a viable polymer electronics competency.

  16. Culture experiments on conductive polymers

    International Nuclear Information System (INIS)

    Onoda, Mitsuyoshi

    2012-01-01

    Fibroblast L929 and myoblast C2C12 cells of the mouse connective tissue origin were sown on the surface of conductive polymer films (polypyrrole, PPy and poly(3,4-ethylenedioxythiophene), PEDOT) in the cell culture medium, and the proliferative process of these cells was observed. Without changing the form, fibroblast L929 and myoblast C2C12 cells were observed to proliferate almost similarly to the cell which cultured on a dish on the market and to maintain compatibility. In other word, it has been understood these two kinds of conductive polymers used in this study, the PEDOT films maintain the secretion function of the cell cultured on the surface of these polymers. Therefore, the PPy- and the PEDOT-coated electrode suggested the possibility usable as a nerve stimulation electrode with biocompatibility, because these polymers were effective to culture the cell.

  17. Finely divided, irradiated tetrafluorethylene polymers

    International Nuclear Information System (INIS)

    Brown, M.T.; Rodway, W.G.

    1977-01-01

    Dry non-sticky fine lubricant powders are made by γ-irradiation of unsintered coagulated dispersion grade tetrafluoroethylene polymers. These powders may also be dispersed in an organic medium for lubricating purposes

  18. Conducting Polymer 3D Microelectrodes

    Directory of Open Access Journals (Sweden)

    Jenny Emnéus

    2010-12-01

    Full Text Available Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared with electrodes coated with only metal. An electrochemical characterization of gold/polypyrrole electrodes showed exceptional electrochemical behavior and activity. PC12 cells were finally cultured on the investigated materials as a preliminary biocompatibility assessment. These results show that the described electrodes are possibly suitable for future in-vitro neurological measurements.

  19. NMR Studies of Polymer Nanocomposites

    National Research Council Canada - National Science Library

    Greenbaum, Steve

    2001-01-01

    ... of their kind ever published. Standard ambient pressure results for lithium ion conducting polymer electrolytes containing nanoscopic silica are included, as well as the description of a novel scheme to produce highly conducting...

  20. Polyphosphazine-based polymer materials

    Science.gov (United States)

    Fox, Robert V.; Avci, Recep; Groenewold, Gary S.

    2010-05-25

    Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

  1. Water Soluble Polymers for Pharmaceutical Applications

    OpenAIRE

    Veeran Gowda Kadajji; Guru V. Betageri

    2011-01-01

    Advances in polymer science have led to the development of novel drug delivery systems. Some polymers are obtained from natural resources and then chemically modified for various applications, while others are chemically synthesized and used. A large number of natural and synthetic polymers are available. In the present paper, only water soluble polymers are described. They have been explained in two categories (1) synthetic and (2) natural. Drug polymer conjugates, block copolymers, hydrogel...

  2. Fabrication of combined-scale nano- and microfluidic polymer systems using a multilevel dry etching, electroplating and molding process

    DEFF Research Database (Denmark)

    Tanzi, Simone; Østergaard, Peter Friis; Matteucci, Marco

    2012-01-01

    Microfabricated single-cell capture and DNA stretching devices have been produced by injection molding. The fabrication scheme employed deep reactive ion etching in a silicon substrate, electroplating in nickel and molding in cyclic olefin polymer. This work proposes technical solutions to fabric......Microfabricated single-cell capture and DNA stretching devices have been produced by injection molding. The fabrication scheme employed deep reactive ion etching in a silicon substrate, electroplating in nickel and molding in cyclic olefin polymer. This work proposes technical solutions...

  3. Ring closure in actin polymers

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Supurna, E-mail: supurna@rri.res.in [Raman Research Institute, Bangalore 560080 (India); Chattopadhyay, Sebanti [Doon University, Dehradun 248001 (India)

    2017-03-18

    We present an analysis for the ring closure probability of semiflexible polymers within the pure bend Worm Like Chain (WLC) model. The ring closure probability predicted from our analysis can be tested against fluorescent actin cyclization experiments. We also discuss the effect of ring closure on bend angle fluctuations in actin polymers. - Highlights: • Ring closure of biopolymers. • Worm like chain model. • Predictions for experiments.

  4. Stochastic Models of Polymer Systems

    Science.gov (United States)

    2016-01-01

    Distribution Unlimited Final Report: Stochastic Models of Polymer Systems The views, opinions and/or findings contained in this report are those of the...ADDRESS. Princeton University PO Box 0036 87 Prospect Avenue - 2nd floor Princeton, NJ 08544 -2020 14-Mar-2014 ABSTRACT Number of Papers published in...peer-reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: Stochastic Models of Polymer Systems Report Title

  5. High cation transport polymer electrolyte

    Science.gov (United States)

    Gerald, II, Rex E.; Rathke, Jerome W [Homer Glen, IL; Klingler, Robert J [Westmont, IL

    2007-06-05

    A solid state ion conducting electrolyte and a battery incorporating same. The electrolyte includes a polymer matrix with an alkali metal salt dissolved therein, the salt having an anion with a long or branched chain having not less than 5 carbon or silicon atoms therein. The polymer is preferably a polyether and the salt anion is preferably an alkyl or silyl moiety of from 5 to about 150 carbon/silicon atoms.

  6. Radiation processing of natural polymer

    International Nuclear Information System (INIS)

    Khairul Zaman; Kamaruddin Hashim; Zulkafli Ghazali; Mohd Hilmi Mahmood; Jamaliah Sharif

    2006-01-01

    Radiation processing of natural polymer has been the subject of interest of countries in this region in the past 5 ∼ 7 years. Although some of the output of the research have been commercialized in particular for the applications in the agriculture and healthcare sectors, the potential applications of radiation processing of natural polymers in the medical sector are yet to be fully understood and developed. (author)

  7. Nanoporous polymer liquid core waveguides

    DEFF Research Database (Denmark)

    Gopalakrishnan, Nimi; Christiansen, Mads Brøkner; Ndoni, Sokol

    2010-01-01

    We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented.......We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented....

  8. Graphene-Based Polymer Nanocomposites

    Science.gov (United States)

    2015-03-31

    polymerize in-situ around the fillers or even graft to them [71], thus it overcomes the problem of dramatically increased viscosity of the polymer...filler dispersion, increased polymer viscosity during processing and filler damage due to thermal degradation or strong shear forces [3, 82]. At...123, 124]. Figure 1.12 (a) SEM image of the fracture surface of GO/PVA nanocomposite film [85]. (b) TEM image of a clay reinforced Nylon-6

  9. Photochemistry of DNA containing iodinated cytosine

    Energy Technology Data Exchange (ETDEWEB)

    Rahn, R O; Stafford, R S [Oak Ridge National Lab., TN (USA)

    1979-10-01

    Irradiation at 313 nm of compounds containing iodinated cytosine moieties results in the photolysis of iodine. Photolysis occurs with a quantum yield of 0.022-0.024 for 5-iododeoxycytidine and 5-iododeoxycytidine monophosphate, and 0.004-0.008 for iodinated DNA as well as for iodinated polycytidylate. Photodegradation of the cytosine moiety occurs when air is present during irradiation, presumably due to the reaction of oxygen with the cytosyl radical formed when iodine is lost. This oxygen promoted photodegradation destroys the cytosine chromophore and is complete in the monomers but occurs to only a limited extent in the polymers. In the absence of oxygen or in the presence of ethanol, photodegradation is prevented and the loss of iodine leads exclusively to the formation of the cytosine chromophore. In DNA, the loss of iodine is accompanied by the formation of sugar damage and/or chain breaks. As measured by sedimentation in alkaline sucrose gradients, approximately one break is made for every six iodines lost in denatured DNA. The frequency of chain breakage per iodine photolyzed is reduced 2-fold in renatured DNA. Analysis in neutral gradients suggests that half of the breaks observed in alkali are alkali-labile bonds. Both ethanol and cysteamine reduce the number of chain breaks in alkali by approximately 3-fold.

  10. Polymer Brushes: Synthesis, Characterization, Applications

    Science.gov (United States)

    Advincula, Rigoberto C.; Brittain, William J.; Caster, Kenneth C.; Rühe, Jürgen

    2004-09-01

    Materials scientists, polymer chemists, surface physicists and materials engineers will find this book a complete and detailed treatise on the field of polymer brushes, their synthesis, characterization and manifold applications. In a first section, the various synthetic pathways and different surface materials are introduced and explained, followed by a second section covering important aspects of characterization and analysis in both flat surfaces and particles. These specific surface initiated polymerization (SIP) systems such as linear polymers, homopolymers, block copolymers, and hyperbranched polymers are unique compared to previously reported systems by chemisorption or physisorption. They have found their way in both large-scale and miniature applications of polymer brushes, which is covered in the last section. Such 'hairy' surfaces offer fascinating opportunities for addressing numerous problems of both academic and, in particular, industrial interest: high-quality, functional or protective coatings, composite materials, surface engineered particles, metal-organic interfaces, biological applications, micro-patterning, colloids, nanoparticles, functional devices, and many more. It is the desire of the authors that this book will be of benefit to readers who want to "brush-up on polymers".

  11. Osmotic load from glucose polymers.

    Science.gov (United States)

    Koo, W W; Poh, D; Leong, M; Tam, Y K; Succop, P; Checkland, E G

    1991-01-01

    Glucose polymer is a carbohydrate source with variable chain lengths of glucose units which may result in variable osmolality. The osmolality of two commercial glucose polymers was measured in reconstituted powder infant formulas, and the change in osmolality of infant milk formulas at the same increases in energy density (67 kcal/dL to 81 and 97 kcal/dL) from the use of additional milk powder or glucose polymers was compared. All samples were prepared from powders (to nearest 0.1 mg), and osmolality was measured by freezing point depression. For both glucose polymers the within-batch variability of the measured osmolality was less than 3.5%, and between-batch variability of the measured osmolality was less than 9.6%. The measured osmolality varies linearly with energy density (p less than 0.001) and was highest in infant formula reconstituted from milk powder alone. However, there exist significant differences in the measured osmolality between different glucose polymer preparations. At high energy densities (greater than or equal to 97 kcal/dL), infant milk formulas prepared with milk powder alone or with the addition of certain glucose polymer preparation may have high osmolality (greater than or equal to 450 mosm/kg) and theoretically predispose the infant to complications of hyperosmotic feeds.

  12. UV-cured polymer optics

    Science.gov (United States)

    Piñón, Victor; Santiago, Freddie; Vogelsberg, Ashten; Davenport, Amelia; Cramer, Neil

    2017-10-01

    Although many optical-quality glass materials are available for use in optical systems, the range of polymeric materials is limited. Polymeric materials have some advantages over glass when it comes to large-scale manufacturing and production. In smaller scale systems, they offer a reduction in weight when compared to glass counterparts. This is especially important when designing optical systems meant to be carried by hand. We aimed to expand the availability of polymeric materials by exploring both crown-like and flint-like polymers. In addition, rapid and facile production was also a goal. By using UV-cured thiolene-based polymers, we were able to produce optical materials within seconds. This enabled the rapid screening of a variety of polymers from which we down-selected to produce optical flats and lenses. We will discuss problems with production and mitigation strategies in using UV-cured polymers for optical components. Using UV-cured polymers present a different set of problems than traditional injection-molded polymers, and these issues are discussed in detail. Using these produced optics, we integrated them into a modified direct view optical system, with the end goal being the development of drop-in replacements for glass components. This optical production strategy shows promise for use in lab-scale systems, where low-cost methods and flexibility are of paramount importance.

  13. Polymer reinforcement of cement systems

    International Nuclear Information System (INIS)

    Swamy, R.N.

    1979-01-01

    In the last couple of decades several cement- and concrete-based composites have come into prominence. Of these, cement-polymer composites, like cement-fibre composites, have been recognised as very promising, and considerable research and development on their properties, fabrication methods and application are in progress. Of the three types of concrete materials which incorporate polymers to form composites, polymer impregnated concrete forms a major development in which hardened concrete is impregnated with a liquid monomer which is subsequently polymerized to form a rigid polymer network in the pores of the parent material. In this first part of the extensive review of the polymer reinforcement of cement systems, the process technology of the various monomer impregnation techniques and the properties of the impregnated composite are assessed critically. It is shown that the high durability and superior performance of polymer impregnated concrete can provide an economic and competitive alternative in in situ strengthening, and in other areas where conventional concrete can only at best provide adequate performance. The review includes a section on radiation-induced polymerization. (author)

  14. Fast phylogenetic DNA barcoding

    DEFF Research Database (Denmark)

    Terkelsen, Kasper Munch; Boomsma, Wouter Krogh; Willerslev, Eske

    2008-01-01

    We present a heuristic approach to the DNA assignment problem based on phylogenetic inferences using constrained neighbour joining and non-parametric bootstrapping. We show that this method performs as well as the more computationally intensive full Bayesian approach in an analysis of 500 insect...... DNA sequences obtained from GenBank. We also analyse a previously published dataset of environmental DNA sequences from soil from New Zealand and Siberia, and use these data to illustrate the fact that statistical approaches to the DNA assignment problem allow for more appropriate criteria...... for determining the taxonomic level at which a particular DNA sequence can be assigned....

  15. Radiation and DNA

    Energy Technology Data Exchange (ETDEWEB)

    Riabchenko, N I

    1979-01-01

    Consideration is given to the effects of ionizing radiation on the structure of DNA. Physical and chemical methods of determining radiation damage to the primary (polynucleotide chain and nitrogenous base) and secondary (helical) structure of DNA are discussed, and the effects of ionizing radiation on deoxyribonucleoprotein complexes are considered. The radiolysis of DNA in vitro and in bacterial and mammalian cells is examined and cellular mechanisms for the repair of radiation-damaged DNA are considered, taking into account single-strand and double-strand breaks, gamma-radiation damage and deoxyribonucleoprotein-membrane complex damage. Postradiation DNA degradation in bacteria and lymphatic cells is also discussed.

  16. DNA-Mediated Electrochemistry

    Science.gov (United States)

    Gorodetsky, Alon A.; Buzzeo, Marisa C.

    2009-01-01

    The base pair stack of DNA has been demonstrated as a medium for long range charge transport chemistry both in solution and at DNA-modified surfaces. This chemistry is exquisitely sensitive to structural perturbations in the base pair stack as occur with lesions, single base mismatches, and protein binding. We have exploited this sensitivity for the development of reliable electrochemical assays based on DNA charge transport at self-assembled DNA monolayers. Here we discuss the characteristic features, applications, and advantages of DNA-mediated electrochemistry. PMID:18980370

  17. Synthesis of hydrogel via click chemistry for DNA electrophoresis.

    Science.gov (United States)

    Finetti, Chiara; Sola, Laura; Elliott, Jim; Chiari, Marcella

    2017-09-01

    This work introduces a novel sieving gel for DNA electrophoresis using a classical click chemistry reaction, the copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC), to cross-link functional polymer chains. The efficiency of this reaction provides, under mild conditions, hydrogels with near-ideal network connectivity and improved physical properties. Hydrogel formation via click chemistry condensation of functional polymers does not involve the use of toxic monomers and UV initiation. The performance of the new hydrogel in the separation of double stranded DNA fragments was evaluated in the 2200 TapeStation system, an analytical platform, recently introduced by Agilent that combines the advantages of CE in terms of miniaturization and automation with the simplicity of use of slab gel electrophoresis. The click gel enables addition of florescent dyes prior to electrophoresis with considerable improvement of resolution and separation efficiency over conventional cross-linked polyacrylamide gels. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Oligodeoxyribonucleotides derived from salmon sperm DNA: an alternative to defibrotide.

    Science.gov (United States)

    Hui, Chang-Ye; Guo, Yan; Zhang, Xi; Shao, Jian-Hua; Yang, Xue-Qin; Zhang, Wen

    2013-05-01

    Defibrotide is a single-stranded nucleic acid polymer originally derived from porcine mucosa. Cheap salmon sperm DNA is commercially available and widely used in drug production. In this study, oligodeoxyribonucleotides were successfully obtained from the controlled depolymerization of salmon sperm DNA. The obtained product shared similar chemical and biological properties with defibrotide produced by Gentium SpA, Italy. It was also found that oligodeoxyribonucleotides derived from non-mammalian origins could also directly stimulate tissue plasminogen activator (t-PA) release from cultured human endothelial cells, and enhance fibrinolytic activity in the rabbit. Copyright © 2013 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

  19. Polymer Thin Film Stabilization.

    Science.gov (United States)

    Costa, A. C.; Oslanec, R.; Composto, R. J.; Vlcek, P.

    1998-03-01

    We study the dewetting dynamics of thin polystyrene (PS) films deposited on silicon oxide surfaces using optical (OM) and atomic force (AFM) microscopes. Quantitative analysis of the hole diameter as a function of annealing time at 175^oC shows that blending poly(styrene-block-methyl-methacrylate) (PS-b-PMMA) with PS acts to dramatically slow down the dewetting rate and even stops holes growth before they impinge. AFM studies show that the hole floor is smooth for a pure PS film but contains residual polymer for the blend. At 5% vol., a PS-b-PMMA with high molar mass and low PMMA is a more effective stabilizing agent than a low molar mass/high PMMA additive. The optimum copolymer concentration is 3% vol. beyond which film stability doesn't improve. Although dewetting is slowed down relative to pure PS, PS/PS-b-PMMA bilayers dewet at a faster rate than blends having the same overall additive concentration.

  20. DNA fragmentation in spermatozoa

    DEFF Research Database (Denmark)

    Rex, A S; Aagaard, J.; Fedder, J

    2017-01-01

    Sperm DNA Fragmentation has been extensively studied for more than a decade. In the 1940s the uniqueness of the spermatozoa protein complex which stabilizes the DNA was discovered. In the fifties and sixties, the association between unstable chromatin structure and subfertility was investigated....... In the seventies, the impact of induced DNA damage was investigated. In the 1980s the concept of sperm DNA fragmentation as related to infertility was introduced as well as the first DNA fragmentation test: the Sperm Chromatin Structure Assay (SCSA). The terminal deoxynucleotidyl transferase nick end labelling...... (TUNEL) test followed by others was introduced in the nineties. The association between DNA fragmentation in spermatozoa and pregnancy loss has been extensively investigated spurring the need for a therapeutic tool for these patients. This gave rise to an increased interest in the aetiology of DNA damage...

  1. Biophysics of DNA

    CERN Document Server

    Vologodskii, Alexander

    2015-01-01

    Surveying the last sixty years of research, this book describes the physical properties of DNA in the context of its biological functioning. It is designed to enable both students and researchers of molecular biology, biochemistry and physics to better understand the biophysics of DNA, addressing key questions and facilitating further research. The chapters integrate theoretical and experimental approaches, emphasising throughout the importance of a quantitative knowledge of physical properties in building and analysing models of DNA functioning. For example, the book shows how the relationship between DNA mechanical properties and the sequence specificity of DNA-protein binding can be analyzed quantitatively by using our current knowledge of the physical and structural properties of DNA. Theoretical models and experimental methods in the field are critically considered to enable the reader to engage effectively with the current scientific literature on the physical properties of DNA.

  2. Single Molecule Study of DNA Organization and Recombination

    Science.gov (United States)

    Xiao, Botao

    We have studied five projects related to DNA organization and recombination using mainly single molecule force-spectroscopy and statistical tools. First, HU is one of the most abundant DNA-organizing proteins in bacterial chromosomes and participates in gene regulation. We report experiments that study the dependence of DNA condensation by HU on force, salt and HU concentration. A first important result is that at physiological salt levels, HU only bends DNA, resolving a previous paradox of why a chromosome-compacting protein should have a DNA-stiffening function. A second major result is quantitative demonstration of strong dependencies of HU-DNA dissociation on both salt concentration and force. Second, we have used a thermodynamic Maxwell relation to count proteins driven off large DNAs by tension, an effect important to understanding DNA organization. Our results compare well with estimates of numbers of proteins HU and Fis in previous studies. We have also shown that a semi-flexible polymer model describes our HU experimental data well. The force-dependent binding suggests mechano-chemical mechanisms for gene regulation. Third, the elusive role of protein H1 in chromatin has been clarified with purified H1 and Xenopus extracts. We find that H1 compacts DNA by both bending and looping. Addition of H1 enhances chromatin formation and maintains the plasticity of the chromatin. Fourth, the topology and mechanics of DNA twisting are critical to DNA organization and recombination. We have systematically measured DNA extension as a function of linking number density from 0.08 to -2 with holding forces from 0.2 to 2.4 pN. Unlike previous proposals, the DNA extension decreases with negative linking number. Finally, DNA recombination is a dynamic process starting from enzyme-DNA binding. We report that the Int-DBD domain of lambda integrase binds to DNA without compaction at low Int-DBD concentration. High concentration of Int-DBD loops DNA below a threshold force

  3. Complexes of poly(ethylene glycol)-based cationic random copolymer and calf thymus DNA: a complete biophysical characterization.

    Science.gov (United States)

    Nisha, C K; Manorama, Sunkara V; Ganguli, Munia; Maiti, Souvik; Kizhakkedathu, Jayachandran N

    2004-03-16

    Complete biophysical characterization of complexes (polyplexes) of cationic polymers and DNA is needed to understand the mechanism underlying nonviral therapeutic gene transfer. In this article, we propose a new series of synthesized random cationic polymers (RCPs) from methoxy poly(ethylene glycol) monomethacrylate (MePEGMA) and (3-(methacryloylamino)propyl)trimethylammonium chloride with different mole ratios (32:68, 11:89, and 6:94) which could be used as a model system to address and answer the basic questions relating to the mechanism of the interaction of calf thymus DNA (CT-DNA) and cationic polymers. The solubility of the complexes of CT-DNA and RCP was followed by turbidity measurements. It has been observed that complexes of RCP with 68 mol % MePEGMA precipitate near the charge neutralization point, whereas complexes of the other two polymers are water-soluble and stable at all compositions. Dnase 1 digestion experiments show that DNA is inaccessible when it forms complexes with RCP. Ethidium bromide exclusion and gel electrophoretic mobility show that both polymers are capable of binding with CT-DNA. Atomic force microscopy images in conjunction with light scattering experiments showed that the complexes are spherical in nature and 75-100 nm in diameter. Circular dichroism spectroscopy studies indicated that the secondary structure of DNA in the complexes is not perturbed due to the presence of poly(ethylene glycol) segments in the polymer. Furthermore, we used a combination of spectroscopic and calorimetric techniques to determine complete thermodynamic profiles accompanying the helix-coil transition of CT-DNA in the complexes. UV and differential scanning calorimetry melting experiments revealed that DNA in the complexes is more stable than in the free state and the extent of stability depends on the polymer composition. Isothermal titration calorimetry experiments showed that the binding of these RCPs to CT-DNA is associated with small exothermic

  4. Development of polymer films by the coalescence of polymer particles in powdered and aqueous polymer-modified mortars

    International Nuclear Information System (INIS)

    Afridi, M.U.K.; Ohama, Y.; Demura, K.; Iqbal, M.Z.

    2003-01-01

    This paper evaluates and compares the coalescence of polymer particles (continuous polymer films formation) in powdered polymer-modified mortars (PPMMs) and aqueous polymer-modified mortars (APMMs). Polymer-modified mortars (PMMs) using various redispersible polymer powders (powdered cement modifiers) and polymer dispersions (aqueous cement modifiers) were prepared by varying the polymer-cement ratio (P/C) and were tested for the characterization of polymer films using a scanning electron microscope (SEM) after curing for 28 days. It is concluded from the test results that mortar constituents of unmodified mortar (UMM) are loosely joined with each other due to the absence of polymer films, thus having a structure with comparatively lower mechanical and durability characteristics. By contrast, mortar constituents in PPMMs and APMMs are compactly joined with each other due to the presence of interweaving polymer films, thereby forming a monolithic structure with improved mechanical and durability characteristics. However, the results make obvious the poor coalescence of polymer particles or development of inferior quality polymers films in PPMMs as compared to that observed in APMMs. Moreover, PPMMs show less uniform distribution of polymer films as compared to that in APMMs. Different powdered cement modifiers have different film-forming capabilities. However, such difference is hardly recognized in aqueous cement modifiers. The polymer films in PPMMs and APMMs may acquire different structures. They may appear as mesh-like, thread-like, rugged, dense or fibrous with fine or rough surfaces. Development of coherent polymer films is not well pronounced at a P/C of 5% in PPMMs, whereas sometimes coherent polymer films are observed at a P/C of 5% in APMMs. At a P/C of 10% or more, fully developed, coherent polymer films are observed in both PPMMs and APMMs

  5. Long-range charge transport in single G-quadruplex DNA molecules

    DEFF Research Database (Denmark)

    Livshits, Gideon I.; Stern, Avigail; Rotem, Dvir

    2014-01-01

    DNA and DNA-based polymers are of interest in molecular electronics because of their versatile and programmable structures. However, transport measurements have produced a range of seemingly contradictory results due to differences in the measured molecules and experimental set-ups, and transport......DNA and DNA-based polymers are of interest in molecular electronics because of their versatile and programmable structures. However, transport measurements have produced a range of seemingly contradictory results due to differences in the measured molecules and experimental set......-ups, and transporting significant current through individual DNA-based molecules remains a considerable challenge. Here, we report reproducible charge transport in guanine-quadruplex (G4) DNA molecules adsorbed on a mica substrate. Currents ranging from tens of picoamperes to more than 100 pA were measured in the G4......-DNA over distances ranging from tens of nanometres to more than 100 nm. Our experimental results, combined with theoretical modelling, suggest that transport occurs via a thermally activated long-range hopping between multi-tetrad segments of DNA. These results could re-ignite interest in DNA...

  6. Polymer Nanocomposites with Prescribed Morphology: Going Beyond Nanoparticle-Filled Polymers (Preprint)

    National Research Council Canada - National Science Library

    Vaia, Richard A; Maguire, John F

    2006-01-01

    Polymer nanocomposites (PNCs), i.e., nanoparticles (spheres, rods, and plates) dispersed in a polymer matrix, have garnered substantial academic and industrial interest since their inception, ca. 1990...

  7. Strong Selective Adsorption of Polymers.

    Science.gov (United States)

    Ge, Ting; Rubinstein, Michael

    2015-06-09

    A scaling theory is developed for selective adsorption of polymers induced by the strong binding between specific monomers and complementary surface adsorption sites. By "selective" we mean specific attraction between a subset of all monomers, called "sticky", and a subset of surface sites, called "adsorption sites". We demonstrate that, in addition to the expected dependence on the polymer volume fraction ϕ bulk in the bulk solution, selective adsorption strongly depends on the ratio between two characteristic length scales, the root-mean-square distance l between neighboring sticky monomers along the polymer, and the average distance d between neighboring surface adsorption sites. The role of the ratio l / d arises from the fact that a polymer needs to deform to enable the spatial commensurability between its sticky monomers and the surface adsorption sites for selective adsorption. We study strong selective adsorption of both telechelic polymers with two end monomers being sticky and multisticker polymers with many sticky monomers between sticky ends. For telechelic polymers, we identify four adsorption regimes at l / d 1, we expect that the adsorption layer at exponentially low ϕ bulk consists of separated unstretched loops, while as ϕ bulk increases the layer crosses over to a brush of extended loops with a second layer of weakly overlapping tails. For multisticker chains, in the limit of exponentially low ϕ bulk , adsorbed polymers are well separated from each other. As l / d increases, the conformation of an individual polymer changes from a single-end-adsorbed "mushroom" to a random walk of loops. For high ϕ bulk , adsorbed polymers at small l / d are mushrooms that cover all the adsorption sites. At sufficiently large l / d , adsorbed multisticker polymers strongly overlap. We anticipate the formation of a self-similar carpet and with increasing l / d a two-layer structure with a brush of loops covered by a self-similar carpet. As l / d exceeds the

  8. Dihydroxybenzene/benzoquinone-containing polymers: organic redox polymers

    Energy Technology Data Exchange (ETDEWEB)

    Moulay, S. [Universite de Blida, Lab. de Chimie-Physique Macromoleculaire, Institut de Chimie Industrielle (Algeria)

    2000-08-01

    Polymers containing hydroquinone, catechol or their corresponding benzoquinones are a special class of redox polymers. Three pathways of their syntheses are possible: condensation polymerization of suitable monomers, addition polymerization of vinyl monomers containing redox moiety, and chemical attachment of redox unit onto pre-made polymeric matrix. A range of functionalized matrices have been employed such as polyethers, polyesters, polycarbonates, polyurethanes, polyamides and others. Protection of their phenolic functionality has conducted to chemically interesting redox polymer precursors. The presence of a redox moiety coupled with the extant functionalization of the polymer matrix makes the materials very valuable, of wide properties and consequently of vast applicability. For instance, in the oil field, some polymers such as carboxy-methyl-cellulose (CMC) are often applied as to bring about a viscosity improvement and therefore to facilitate the oil drilling. In this regard, Patel evaluated sulfo-alkylated polymeric catechol, namely sulfo-methylated and sulfo-ethylated resins. Indeed, polymeric catechol chemically modified as such exhibited a marked ability to control the viscosity, the gel strength, as well as the filtrate loss of aqueous oil drilling fluids.

  9. Nanostructured polymer membranes for proton conduction

    Science.gov (United States)

    Balsara, Nitash Pervez; Park, Moon Jeong

    2013-06-18

    Polymers having an improved ability to entrain water are characterized, in some embodiments, by unusual humidity-induced phase transitions. The described polymers (e.g., hydrophilically functionalized block copolymers) have a disordered state and one or more ordered states (e.g., a lamellar state, a gyroid state, etc.). In one aspect, the polymers are capable of undergoing a disorder-to-order transition while the polymer is exposed to an increasing temperature at a constant relative humidity. In some aspects the polymer includes a plurality of portions, wherein a first portion forms proton-conductive channels within the membrane and wherein the channels have a width of less than about 6 nm. The described polymers are capable of entraining and preserving water at high temperature and low humidity. Surprisingly, in some embodiments, the polymers are capable of entraining greater amounts of water with the increase of temperature. The polymers can be used in Polymer Electrolyte Membranes in fuel cells.

  10. Validation of the use of an artificial mitochondrial reporter DNA vector containing a Cytomegalovirus promoter for mitochondrial transgene expression.

    Science.gov (United States)

    Yamada, Yuma; Ishikawa, Takuya; Harashima, Hideyoshi

    2017-08-01

    Mitochondria have their own gene expression system that is independent of the nuclear system, and control cellular functions in cooperation with the nucleus. While a number of useful technologies for achieving nuclear transgene expression have been reported, only a few have focused on mitochondria. In this study, we validated the utility of an artificial mitochondrial DNA vector with a virus promoter on mitochondrial transgene expression. We designed and constructed pCMV-mtLuc (CGG) that contains a CMV promotor derived from Cytomegalovirus and an artificial mitochondrial genome with a NanoLuc (Nluc) luciferase gene that records adjustments to the mitochondrial codon system. Nluc luciferase activity measurements showed that the pCMV-mtLuc (CGG) efficiently produced the Nluc luciferase protein in human HeLa cells. Moreover, we optimized the mitochondrial transfection of pCMV-mtLuc (CGG) using a MITO-Porter system, a liposome-based carrier for mitochondrial delivery via membrane fusion. As a result, we found that transfection of pCMV-mtLuc (CGG) by MITO-Porter modified with the KALA peptide (cationic amphipathic cell-penetrating peptide) showed a high mitochondrial transgene expression. The developed mitochondrial transgene expression system represents a potentially useful tool for the fields of nanoscience and nanotechnology for controlling the intracellular microenvironment via the regulation of mitochondrial function and promises to open additional innovative research fields of study. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Free radical transfer in polymers

    International Nuclear Information System (INIS)

    Sonntag, C. von; Bothe, E.; Ulanski, P.

    1998-01-01

    For the present study of free-radical transfer in polymers pulse radiolysis and product studies have been carried out in aqueous solutions using thus far only the water-soluble polymers polyacrylic acid, polymethacrylic acid and polyvinyl alcohol. When OH radicals, generated in the radiolysis of N 2 O-saturated aqueous solutions, react with polymers the lifetime of the polymer radical thus created very much depends on the number of radicals per polymer chain. When there are a large number of radicals per chain their bimolecular decay may be faster than the corresponding (diffusion controlled) decay of monomeric radicals, but when the macromolecule contains only few or even just one radical their lifetime is considerably prolonged. Highly charged polymers such as polyacrylic acid at high pH attain a rod-like conformation which again favors a long lifetime of the radicals. Under such conditions, radical transfer reactions can occur. For example, in polyacrylic acid OH radicals generate two kinds of radicals side by side. The radical in β-position to the carboxylate group converts into the thermodynamically more stable α-radicals by an H-transfer reaction as can be followed by spectrophotometry. Besides radical transfer reactions β-fragmentation reactions occur causing chain scission. Such reactions can be followed in a pulse radiolysis experiment by conductometry, because counter ions are released upon chain scission. Such a process is especially effective in the case of polymethacrylic acid, where it results in a chain depolymerization. An intramolecular H-abstraction is also observed in the γ-radiolysis of polyacrylic acid with the corresponding peroxyl radicals. This causes a chain reaction to occur. The resulting hydroperoxides are unstable and decarboxylate given rise to acetylacetone-like products. In polyvinyl alcohol the peroxyl radicals in α-position to the alcohol function undergo HO 2 -elimination. This prevents a scission of the polymer chain in the

  12. The effect of volume exclusion on the formation of DNA minicircle networks: implications to kinetoplast DNA

    International Nuclear Information System (INIS)

    Diao, Y; Hinson, K; Sun, Y; Arsuaga, J

    2015-01-01

    Kinetoplast DNA (kDNA) is the mitochondrial of DNA of disease causing organisms such as Trypanosoma Brucei (T. Brucei) and Trypanosoma Cruzi (T. Cruzi). In most organisms, KDNA is made of thousands of small circular DNA molecules that are highly condensed and topologically linked forming a gigantic planar network. In our previous work we have developed mathematical and computational models to test the confinement hypothesis, that is that the formation of kDNA minicircle networks is a product of the high DNA condensation achieved in the mitochondrion of these organisms. In these studies we studied three parameters that characterize the growth of the network topology upon confinement: the critical percolation density, the mean saturation density and the mean valence (i.e. the number of mini circles topologically linked to any chosen minicircle). Experimental results on insect-infecting organisms showed that the mean valence is equal to three, forming a structure similar to those found in medieval chain-mails. These same studies hypothesized that this value of the mean valence was driven by the DNA excluded volume. Here we extend our previous work on kDNA by characterizing the effects of DNA excluded volume on the three descriptive parameters. Using computer simulations of polymer swelling we found that (1) in agreement with previous studies the linking probability of two minicircles does not decrease linearly with the distance between the two minicircles, (2) the mean valence grows linearly with the density of minicircles and decreases with the thickness of the excluded volume, (3) the critical percolation and mean saturation densities grow linearly with the thickness of the excluded volume. Our results therefore suggest that the swelling of the DNA molecule, due to electrostatic interactions, has relatively mild implications on the overall topology of the network. Our results also validate our topological descriptors since they appear to reflect the changes in the

  13. The effect of volume exclusion on the formation of DNA minicircle networks: implications to kinetoplast DNA

    Science.gov (United States)

    Diao, Y.; Hinson, K.; Sun, Y.; Arsuaga, J.

    2015-10-01

    Kinetoplast DNA (kDNA) is the mitochondrial of DNA of disease causing organisms such as Trypanosoma Brucei (T. Brucei) and Trypanosoma Cruzi (T. Cruzi). In most organisms, KDNA is made of thousands of small circular DNA molecules that are highly condensed and topologically linked forming a gigantic planar network. In our previous work we have developed mathematical and computational models to test the confinement hypothesis, that is that the formation of kDNA minicircle networks is a product of the high DNA condensation achieved in the mitochondrion of these organisms. In these studies we studied three parameters that characterize the growth of the network topology upon confinement: the critical percolation density, the mean saturation density and the mean valence (i.e. the number of mini circles topologically linked to any chosen minicircle). Experimental results on insect-infecting organisms showed that the mean valence is equal to three, forming a structure similar to those found in medieval chain-mails. These same studies hypothesized that this value of the mean valence was driven by the DNA excluded volume. Here we extend our previous work on kDNA by characterizing the effects of DNA excluded volume on the three descriptive parameters. Using computer simulations of polymer swelling we found that (1) in agreement with previous studies the linking probability of two minicircles does not decrease linearly with the distance between the two minicircles, (2) the mean valence grows linearly with the density of minicircles and decreases with the thickness of the excluded volume, (3) the critical percolation and mean saturation densities grow linearly with the thickness of the excluded volume. Our results therefore suggest that the swelling of the DNA molecule, due to electrostatic interactions, has relatively mild implications on the overall topology of the network. Our results also validate our topological descriptors since they appear to reflect the changes in the

  14. Longitudinal relaxation of initially straight flexible and stiff polymers

    Science.gov (United States)

    Dimitrakopoulos, Panagiotis; Dissanayake, Inuka

    2004-11-01

    The present talk considers the relaxation of a single flexible or stiff polymer chain from an initial straight configuration in a viscous solvent. This problem commonly arises when strong flows are turned off in both industrial and biological applications. The problem is also motivated by recent experiments with single biopolymer molecules relaxing after being fully extended by applied forces as well as by the recent development of micro-devices involving stretched tethered biopolymers. Our results are applicable to a wide array of synthetic polymers such as polyacrylamides, Kevlar and polyesters as well as biopolymers such as DNA, actin filaments, microtubules and MTV. In this talk we discuss the mechanism of the polymer relaxation as was revealed through Brownian Dynamics simulations covering a broad range of time scales and chain stiffness. After the short-time free diffusion, the chain's longitudinal reduction at early intermediate times is shown to constitute a universal behavior for any chain stiffness caused by a quasi-steady relaxation of tensions associated with the deforming action of the Brownian forces. Stiff chains are shown to exhibit a late intermediate-time longitudinal reduction associated with a relaxation of tensions affected by the deforming Brownian and the restoring bending forces. The longitudinal and transverse relaxations are shown to obey different laws, i.e. the chain relaxation is anisotropic at all times. In the talk, we show how from the knowledge of the relaxation mechanism, we can predict and explain the polymer properties including the polymer stress and the solution birefringence. In addition, a generalized stress-optic law is derived valid for any time and chain stiffness. All polymer properties which depend on the polymer length are shown to exhibit two intermediate-time behaviors with the early one to constitute a universal behavior for any chain stiffness. This work was supported in part by the Minta Martin Research Fund. The

  15. Beyond DNA repair: DNA-PK function in cancer

    OpenAIRE

    Goodwin, Jonathan F.; Knudsen, Karen E.

    2014-01-01

    The DNA-dependent protein kinase (DNA-PK) is a pivotal component of the DNA repair machinery that governs the response to DNA damage, serving to maintain genome integrity. However, the DNA-PK kinase component was initially isolated with transcriptional complexes, and recent findings have illuminated the impact of DNA-PK-mediated transcriptional regulation on tumor progression and therapeutic response. DNA-PK expression has also been correlated with poor outcome in selected tumor types, furthe...

  16. Molecular and supramolecular orientation in conducting polymers

    International Nuclear Information System (INIS)

    Aldissi, M.

    1987-01-01

    Intrinsic anisotropy in electrical and optical properties of conducting polymers constitutes a unique aspect that derives π-electron delocalization along the polymer backbone and from the weak inter-chain interaction. To acquire such an intrinsic property, conducting polymers have to be oriented macroscopically and microscopically (at the chain level). A review of the various techniques, including stretch-alignment of the polymer and of precursor polymers, polymerization in ordered media, i.e., in a liquid crystal solvent, and synthesis of liquid crystalline conducting polymers will be given. 29 refs

  17. Polymers for energy storage and conversion

    CERN Document Server

    Mittal, Vikas

    2013-01-01

    One of the first comprehensive books to focus on the role of polymers in the burgeoning energy materials market Polymers are increasingly finding applications in the areas of energy storage and conversion. A number of recent advances in the control of the polymer molecular structure which allows the polymer properties to be more finely tuned have led to these advances and new applications. Polymers for Energy Storage and Conversion assimilates these advances in the form of a comprehensive text that includes the synthesis and properties of a large number of polymer systems for

  18. Editorial of the Special Issue Antimicrobial Polymers

    Directory of Open Access Journals (Sweden)

    Iolanda Francolini

    2013-09-01

    Full Text Available The special issue “Antimicrobial Polymers” includes research and review papers concerning the recent advances on preparation of antimicrobial polymers and their relevance to industrial settings and biomedical field. Antimicrobial polymers have recently emerged as promising candidates to fight microbial contamination onto surfaces thanks to their interesting properties. In this special issue, the main strategies pursued for developing antimicrobial polymers, including polymer impregnation with antimicrobial agents or synthesis of polymers bearing antimicrobial moieties, were discussed. The future application of these polymers either in industrial or healthcare settings could result in an extremely positive impact not only at the economic level but also for the improvement of quality of life.

  19. Cycloadditions in modern polymer chemistry.

    Science.gov (United States)

    Delaittre, Guillaume; Guimard, Nathalie K; Barner-Kowollik, Christopher

    2015-05-19

    Synthetic polymer chemistry has undergone two major developments in the last two decades. About 20 years ago, reversible-deactivation radical polymerization processes started to give access to a wide range of polymeric architectures made from an almost infinite reservoir of functional building blocks. A few years later, the concept of click chemistry revolutionized the way polymer chemists approached synthetic routes. Among the few reactions that could qualify as click, the copper-catalyzed azide-alkyne cycloaddition (CuAAC) initially stood out. Soon, many old and new reactions, including cycloadditions, would further enrich the synthetic macromolecular chemistry toolbox. Whether click or not, cycloadditions are in any case powerful tools for designing polymeric materials in a modular fashion, with a high level of functionality and, sometimes, responsiveness. Here, we wish to describe cycloaddition methodologies that have been reported in the last 10 years in the context of macromolecular engineering, with a focus on those developed in our laboratories. The overarching structure of this Account is based on the three most commonly encountered cycloaddition subclasses in organic and macromolecular chemistry: 1,3-dipolar cycloadditions, (hetero-)Diels-Alder cycloadditions ((H)DAC), and [2+2] cycloadditions. Our goal is to briefly describe the relevant reaction conditions, the advantages and disadvantages, and the realized polymer applications. Furthermore, the orthogonality of most of these reactions is highlighted because it has proven highly beneficial for generating unique, multifunctional polymers in a one-pot reaction. The overview on 1,3-dipolar cycloadditions is mostly centered on the application of CuAAC as the most travelled route, by far. Besides illustrating the capacity of CuAAC to generate complex polymeric architectures, alternative 1,3-dipolar cycloadditions operating without the need for a catalyst are described. In the area of (H)DA cycloadditions

  20. Smart Polymers with Special Wettability.

    Science.gov (United States)

    Chang, Baisong; Zhang, Bei; Sun, Taolei

    2017-01-01

    Surface wettability plays a key role in addressing issues ranging from basic life activities to our daily life, and thus being able to control it is an attractive goal. Learning from nature, both of its structure and function, brings us much inspiration in designing smart polymers to tackle this major challenge. Life functions particularly depend on biomolecular recognition-induced interfacial properties from the aqueous phase onto either "soft" cell and tissue or "hard" inorganic bone and tooth surfaces. The driving force is noncovalent weak interactions rather than strong covalent combinations. An overview is provided of the weak interactions that perform vital actions in mediating biological processes, which serve as a basis for elaborating multi-component polymers with special wettabilities. The role of smart polymers from molecular recognitions to macroscopic properties are highlighted. The rationale is that highly selective weak interactions are capable of creating a dynamic synergetic communication in the building components of polymers. Biomolecules could selectively induce conformational transitions of polymer chains, and then drive a switching of physicochemical properties, e.g., roughness, stiffness and compositions, which are an integrated embodiment of macroscopic surface wettabilities. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Determination of size distribution of small DNA fragments by polyacrylamide gel electrophoresis

    International Nuclear Information System (INIS)

    Lau How Mooi

    1998-01-01

    Size distribution determination of DNA fragments can be normally determined by the agarose gel electrophoresis, including the normal DNA banding pattern analysis. However this method is only good for large DNA, such as the DNA of the size of kilo base pairs to mega base pairs range. DNA of size less than kilo base pairs is difficult to be quantified by the agarose gel method. Polyacrylamide gel electrophoresis however can be used to measure the quantity of DNA fragments of size less than kilo base pairs in length, down to less than ten base pairs. This method is good for determining the quantity of the smaller size DNA, single stranded polymers or even some proteins, if the known standards are available. In this report detail description of the method of preparing the polyacrylamide gel, and the experimental set up is discussed. Possible uses of this method, and the comparison with the standard sizes of DNA is also shown. This method is used to determine the distribution of the amount of the fragmented DNA after the Calf-thymus DNA has been exposed to various types of radiation and of different doses. The standards were used to determine the sizes of the fragmented Calf-thymus DNA. The higher the dose the higher is the amount of the smaller size DNA measured

  2. Green polymer chemistry: enzyme catalysis for polymer functionalization.

    Science.gov (United States)

    Sen, Sanghamitra; Puskas, Judit E

    2015-05-21

    Enzyme catalyzed reactions are green alternative approaches to functionalize polymers compared to conventional methods. This technique is especially advantageous due to the high selectivity, high efficiency, milder reaction conditions, and recyclability of enzymes. Selected reactions can be conducted under solventless conditions without the application of metal catalysts. Hence this process is becoming more recognized in the arena of biomedical applications, as the toxicity created by solvents and metal catalyst residues can be completely avoided. In this review we will discuss fundamental aspects of chemical reactions biocatalyzed by Candida antarctica lipase B, and their application to create new functionalized polymers, including the regio- and chemoselectivity of the reactions.

  3. Green Polymer Chemistry: Enzyme Catalysis for Polymer Functionalization

    Directory of Open Access Journals (Sweden)

    Sanghamitra Sen

    2015-05-01

    Full Text Available Enzyme catalyzed reactions are green alternative approaches to functionalize polymers compared to conventional methods. This technique is especially advantageous due to the high selectivity, high efficiency, milder reaction conditions, and recyclability of enzymes. Selected reactions can be conducted under solventless conditions without the application of metal catalysts. Hence this process is becoming more recognized in the arena of biomedical applications, as the toxicity created by solvents and metal catalyst residues can be completely avoided. In this review we will discuss fundamental aspects of chemical reactions biocatalyzed by Candida antarctica lipase B, and their application to create new functionalized polymers, including the regio- and chemoselectivity of the reactions.

  4. Theory of high-force DNA stretching and overstretching.

    Science.gov (United States)

    Storm, C; Nelson, P C

    2003-05-01

    Single-molecule experiments on single- and double-stranded DNA have sparked a renewed interest in the force versus extension of polymers. The extensible freely jointed chain (FJC) model is frequently invoked to explain the observed behavior of single-stranded DNA, but this model does not satisfactorily describe recent high-force stretching data. We instead propose a model (the discrete persistent chain) that borrows features from both the FJC and the wormlike chain, and show that it resembles the data more closely. We find that most of the high-force behavior previously attributed to stretch elasticity is really a feature of the corrected entropic elasticity; the true stretch compliance of single-stranded DNA is several times smaller than that found by previous authors. Next we elaborate our model to allow coexistence of two conformational states of DNA, each with its own stretch and bend elastic constants. Our model is computationally simple and gives an excellent fit through the entire overstretching transition of nicked, double-stranded DNA. The fit gives the first value for the bend stiffness of the overstretched state. In particular, we find the effective bend stiffness for DNA in this state to be about 12 nm k(B)T, a value quite different from either the B-form or single-stranded DNA.

  5. Multifunctional DNA-gold nanoparticles for targeted doxorubicin delivery.

    Science.gov (United States)

    Alexander, Colleen M; Hamner, Kristen L; Maye, Mathew M; Dabrowiak, James C

    2014-07-16

    In this report we describe the synthesis, characterization, and cytotoxic properties of DNA-capped gold nanoparticles having attached folic acid (FA), a thermoresponsive polymer (p), and/or poly(ethylene glycol) (PEG) oligomers that could be used to deliver the anticancer drug doxorubicin (DOX) in chemotherapy. The FA-DNA oligomer used in the construction of the delivery vehicle was synthesized through the reaction of the isolated folic acid N-hydroxysuccinimide ester with the amino-DNA and the conjugated DNA product was purified using high performance liquid chromatography (HPLC). This approach ultimately allowed control of the amount of FA attached to the surface of the delivery vehicle. Cytotoxicity studies using SK-N-SH neuroblastoma cells with drug loaded delivery vehicles were carried out using a variety of exposure times (1-48 h) and recovery times (1-72 h), and in order to access the effects of varying amounts of attached FA, in culture media deficient in FA. DOX loaded delivery vehicles having 50% of the DNA strands with attached FA were more cytotoxic than when all of the strands contained FA. Since FA stimulates cell growth, the reduced cytotoxicity of vehicles fully covered with FA suggests that the stimulatory effects of FA can more than compensate for the cytotoxic effects of the drug on the cell population. While attachment of hexa-ethylene glycol PEG(18) to the surface of the delivery vehicle had no effect on cytotoxicity, 100% FA plus the thermoresponsive polymer resulted in IC50 = 0.48 ± 0.01 for an exposure time of 24 h and a recovery time of 1 h, which is an order of magnitude more cytotoxic than free DOX. Confocal microscopic studies using fluorescence detection showed that SK-N-SH neuroblastoma cells exposed to DOX-loaded vehicles have drug accumulation inside the cell and, in the case of vehicles with attached FA and thermoresponsive polymer, the drug appears more concentrated. Since the biological target of DOX is DNA, the latter

  6. DNA topology and transcription

    Science.gov (United States)

    Kouzine, Fedor; Levens, David; Baranello, Laura

    2014-01-01

    Chromatin is a complex assembly that compacts DNA inside the nucleus while providing the necessary level of accessibility to regulatory factors conscripted by cellular signaling systems. In this superstructure, DNA is the subject of mechanical forces applied by variety of molecular motors. Rather than being a rigid stick, DNA possesses dynamic structural variability that could be harnessed during critical steps of genome functioning. The strong relationship between DNA structure and key genomic processes necessitates the study of physical constrains acting on the double helix. Here we provide insight into the source, dynamics, and biology of DNA topological domains in the eukaryotic cells and summarize their possible involvement in gene transcription. We emphasize recent studies that might inspire and impact future experiments on the involvement of DNA topology in cellular functions. PMID:24755522

  7. Eukaryotic DNA Replication Fork.

    Science.gov (United States)

    Burgers, Peter M J; Kunkel, Thomas A

    2017-06-20

    This review focuses on the biogenesis and composition of the eukaryotic DNA replication fork, with an emphasis on the enzymes that synthesize DNA and repair discontinuities on the lagging strand of the replication fork. Physical and genetic methodologies aimed at understanding these processes are discussed. The preponderance of evidence supports a model in which DNA polymerase ε (Pol ε) carries out the bulk of leading strand DNA synthesis at an undisturbed replication fork. DNA polymerases α and δ carry out the initiation of Okazaki fragment synthesis and its elongation and maturation, respectively. This review also discusses alternative proposals, including cellular processes during which alternative forks may be utilized, and new biochemical studies with purified proteins that are aimed at reconstituting leading and lagging strand DNA synthesis separately and as an integrated replication fork.

  8. Poly(hydroxyethyl methacrylate) based magnetic nanoparticles for plasmid DNA purification from Escherichia coli lysate

    Energy Technology Data Exchange (ETDEWEB)

    Percin, Is Latin-Small-Letter-Dotless-I k [Department of Biology, Hacettepe University, Ankara (Turkey); Karakoc, Veyis [Department of Chemistry, Biochemistry Division, Hacettepe University, Ankara (Turkey); Akgoel, Sinan [Department of Biochemistry, Ege University, Izmir (Turkey); Aksoez, Erol [Department of Biology, Hacettepe University, Ankara (Turkey); Denizli, Adil, E-mail: denizli@hacettepe.edu.tr [Department of Chemistry, Biochemistry Division, Hacettepe University, Ankara (Turkey)

    2012-07-01

    The aim of this study is to prepare poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine) [PHEMAH] magnetic nanoparticles for plasmid DNA (pDNA) purification from Escherichia coli (E. coli) cell lysate. Magnetic nanoparticles were produced by surfactant free emulsion polymerization. mPHEMAH nanoparticles were characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), electron spin resonance (ESR), thermogravimetric analyses (TGA) and transmission electron microscopy (TEM). Surface area, average particle size and size distribution were also performed. Specific surface area of the mPHEMAH nanoparticles was found to be 1180 m{sup 2}/g. Elemental analysis of MAH for nitrogen was estimated as 0.18 mmol/g polymer. The amount of pDNA adsorbed onto the mPHEMAH nanoparticles first increased and then reached a saturation value at around 1.0 mg/mL of pDNA concentration. Compared with the mPHEMA nanoparticles (50 {mu}g/g polymer), the pDNA adsorption capacity of the mPHEMAH nanoparticles (154 mg/g polymer) was improved significantly due to the MAH incorporation into the polymeric matrix. The maximum pDNA adsorption was achieved at 25 Degree-Sign C. The overall recovery of pDNA was calculated as 92%. The mPHEMAH nanoparticles could be used six times without decreasing the pDNA adsorption capacity significantly. The results indicate that the PHEMAH nanoparticles promise high selectivity for pDNA. - Highlights: Black-Right-Pointing-Pointer Magnetic nanoparticles have several advantages over conventional adsorbents. Black-Right-Pointing-Pointer MAH acted as the pseudospecific ligand, ligand immobilization step was eliminated. Black-Right-Pointing-Pointer pDNA adsorption amount was 154 mg/g. Black-Right-Pointing-Pointer Fifty-fold capacity increase was obtained when compared to conventional matrices.

  9. Poly(hydroxyethyl methacrylate) based magnetic nanoparticles for plasmid DNA purification from Escherichia coli lysate

    International Nuclear Information System (INIS)

    Perçin, Işık; Karakoç, Veyis; Akgöl, Sinan; Aksöz, Erol; Denizli, Adil

    2012-01-01

    The aim of this study is to prepare poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine) [PHEMAH] magnetic nanoparticles for plasmid DNA (pDNA) purification from Escherichia coli (E. coli) cell lysate. Magnetic nanoparticles were produced by surfactant free emulsion polymerization. mPHEMAH nanoparticles were characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), electron spin resonance (ESR), thermogravimetric analyses (TGA) and transmission electron microscopy (TEM). Surface area, average particle size and size distribution were also performed. Specific surface area of the mPHEMAH nanoparticles was found to be 1180 m 2 /g. Elemental analysis of MAH for nitrogen was estimated as 0.18 mmol/g polymer. The amount of pDNA adsorbed onto the mPHEMAH nanoparticles first increased and then reached a saturation value at around 1.0 mg/mL of pDNA concentration. Compared with the mPHEMA nanoparticles (50 μg/g polymer), the pDNA adsorption capacity of the mPHEMAH nanoparticles (154 mg/g polymer) was improved significantly due to the MAH incorporation into the polymeric matrix. The maximum pDNA adsorption was achieved at 25 °C. The overall recovery of pDNA was calculated as 92%. The mPHEMAH nanoparticles could be used six times without decreasing the pDNA adsorption capacity significantly. The results indicate that the PHEMAH nanoparticles promise high selectivity for pDNA. - Highlights: ► Magnetic nanoparticles have several advantages over conventional adsorbents. ► MAH acted as the pseudospecific ligand, ligand immobilization step was eliminated. ► pDNA adsorption amount was 154 mg/g. ► Fifty-fold capacity increase was obtained when compared to conventional matrices.

  10. From the Cover: A polymer library approach to suicide gene therapy for cancer

    Science.gov (United States)

    Anderson, Daniel G.; Peng, Weidan; Akinc, Akin; Hossain, Naushad; Kohn, Anat; Padera, Robert; Langer, Robert; Sawicki, Janet A.

    2004-11-01

    Optimal gene therapy for cancer must (i) deliver DNA to tumor cells with high efficiency, (ii) induce minimal toxicity, and (iii) avoid gene expression in healthy tissues. To this end, we generated a library of >500 degradable, poly(-amino esters) for potential use as nonviral DNA vectors. Using high-throughput methods, we screened this library in vitro for transfection efficiency and cytotoxicity. We tested the best performing polymer, C32, in mice for toxicity and DNA delivery after intratumor and i.m. injection. C32 delivered DNA intratumorally 4-fold better than one of the best commercially available reagents, jetPEI (polyethyleneimine), and 26-fold better than naked DNA. Conversely, the highest transfection levels after i.m. administration were achieved with naked DNA, followed by polyethyleneimine; transfection was rarely observed with C32. Additionally, polyethyleneimine induced significant local toxicity after i.m. injection, whereas C32 demonstrated no toxicity. Finally, we used C32 to deliver a DNA construct encoding the A chain of diphtheria toxin (DT-A) to xenografts derived from LNCaP human prostate cancer cells. This construct regulates toxin expression both at the transcriptional level by the use of a chimeric-modified enhancer/promoter sequence of the human prostate-specific antigen gene and by DNA recombination mediated by Flp recombinase. C32 delivery of the A chain of diphtheria toxin DNA to LNCaP xenografts suppressed tumor growth and even caused 40% of tumors to regress in size. Because C32 transfects tumors locally at high levels, transfects healthy muscle poorly, and displays no toxicity, it may provide a vehicle for the local treatment of cancer. prostate | cationic polymers

  11. DNA-based machines.

    Science.gov (United States)

    Wang, Fuan; Willner, Bilha; Willner, Itamar

    2014-01-01

    The base sequence in nucleic acids encodes substantial structural and functional information into the biopolymer. This encoded information provides the basis for the tailoring and assembly of DNA machines. A DNA machine is defined as a molecular device that exhibits the following fundamental features. (1) It performs a fuel-driven mechanical process that mimics macroscopic machines. (2) The mechanical process requires an energy input, "fuel." (3) The mechanical operation is accompanied by an energy consumption process that leads to "waste products." (4) The cyclic operation of the DNA devices, involves the use of "fuel" and "anti-fuel" ingredients. A variety of DNA-based machines are described, including the construction of "tweezers," "walkers," "robots," "cranes," "transporters," "springs," "gears," and interlocked cyclic DNA structures acting as reconfigurable catenanes, rotaxanes, and rotors. Different "fuels", such as nucleic acid strands, pH (H⁺/OH⁻), metal ions, and light, are used to trigger the mechanical functions of the DNA devices. The operation of the devices in solution and on surfaces is described, and a variety of optical, electrical, and photoelectrochemical methods to follow the operations of the DNA machines are presented. We further address the possible applications of DNA machines and the future perspectives of molecular DNA devices. These include the application of DNA machines as functional structures for the construction of logic gates and computing, for the programmed organization of metallic nanoparticle structures and the control of plasmonic properties, and for controlling chemical transformations by DNA machines. We further discuss the future applications of DNA machines for intracellular sensing, controlling intracellular metabolic pathways, and the use of the functional nanostructures for drug delivery and medical applications.

  12. DNA repair and cancer

    International Nuclear Information System (INIS)

    Rathore, Shakuntla; Joshi, Pankaj Kumar; Gaur, Sudha

    2012-01-01

    DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecule that encode it's genome. In human cells, both normal metabolic activities and environmental factors such as UV light and radiation can cause DNA damage, resulting in as many one million individual molecular lesions per day. Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions include potentially harmful mutation in cell's genome which affect the survival of it's daughter cells after it undergoes mitosis. As a consequence, the DNA repair process is constantly active as it responds to damage in the DNA structure. Inherited mutation that affect DNA repair genes are strongly associated with high cancer risks in humans. Hereditary non polyposis colorectal cancer (HNPCC) is strongly associated with specific mutation in the DNA mismatch repair pathway. BRCA1, BRCA2 two famous mutation conferring a hugely increased risk of breast cancer on carrier, are both associated with a large number of DNA repair pathway, especially NHEJ and homologous recombination. Cancer therapy procedures such as chemotherapy and radiotherapy work by overwhelming the capacity of the cell to repair DNA damage, resulting in cell death. Cells that are most rapidly dividing most typically cancer cells are preferentially affected. The side effect is that other non-cancerous but rapidly dividing cells such as stem cells in the bone marrow are also affected. Modern cancer treatment attempt to localize the DNA damage to cells and tissue only associated with cancer, either by physical means (concentrating the therapeutic agent in the region of the tumor) or by biochemical means (exploiting a feature unique to cancer cells in the body). (author)

  13. Nonisotopic DNA probe techniques

    National Research Council Canada - National Science Library

    Kricka, Larry J

    1992-01-01

    The objective of this book is to bring together descriptions of the principal nonisotopic methods for DNA hybridization assays, together with experimental details of the methods, including labelling...

  14. DNA replication and cancer

    DEFF Research Database (Denmark)

    Boyer, Anne-Sophie; Walter, David; Sørensen, Claus Storgaard

    2016-01-01

    A dividing cell has to duplicate its DNA precisely once during the cell cycle to preserve genome integrity avoiding the accumulation of genetic aberrations that promote diseases such as cancer. A large number of endogenous impacts can challenge DNA replication and cells harbor a battery of pathways...... causing DNA replication stress and genome instability. Further, we describe cellular and systemic responses to these insults with a focus on DNA replication restart pathways. Finally, we discuss the therapeutic potential of exploiting intrinsic replicative stress in cancer cells for targeted therapy....

  15. Forensic DNA testing.

    Science.gov (United States)

    Butler, John M

    2011-12-01

    Forensic DNA testing has a number of applications, including parentage testing, identifying human remains from natural or man-made disasters or terrorist attacks, and solving crimes. This article provides background information followed by an overview of the process of forensic DNA testing, including sample collection, DNA extraction, PCR amplification, short tandem repeat (STR) allele separation and sizing, typing and profile interpretation, statistical analysis, and quality assurance. The article concludes with discussions of possible problems with the data and other forensic DNA testing techniques.

  16. Water Soluble Responsive Polymer Brushes

    Directory of Open Access Journals (Sweden)

    Andrew J. Parnell

    2011-12-01

    Full Text Available Responsive polymer brushes possess many interesting properties that enable them to control a range of important interfacial behaviours, including adhesion, wettability, surface adsorption, friction, flow and motility. The ability to design a macromolecular response to a wide variety of external stimuli makes polymer brushes an exciting class of functional materials, and has been made possible by advances in modern controlled polymerization techniques. In this review we discuss the physics of polymer brush response along with a summary of the techniques used in their synthesis. We then review the various stimuli that can be used to switch brush conformation; temperature, solvent quality, pH and ionic strength as well as the relatively new area of electric field actuation We discuss examples of devices that utilise brush conformational change, before highlighting other potential applications of responsive brushes in real world devices.

  17. Diffusion in inhomogeneous polymer membranes

    Science.gov (United States)

    Kasargod, Sameer S.; Adib, Farhad; Neogi, P.

    1995-10-01

    The dual mode sorption solubility isotherms assume, and in instances Zimm-Lundberg analysis of the solubilities show, that glassy polymers are heterogeneous and that the distribution of the solute in the polymer is also inhomogeneous. Under some conditions, the heterogeneities cannot be represented as holes. A mathematical model describing diffusion in inhomogeneous polymer membranes is presented using Cahn and Hilliard's gradient theory. The fractional mass uptake is found to be proportional to the fourth root of time rather than the square root, predicted by Fickian diffusion. This type of diffusion is classified as pseudo-Fickian. The model is compared with one experimental result available. A negative value of the persistence factor is obtained and the results are interpreted.

  18. Dynamic viscosity of polymer solutions

    Energy Technology Data Exchange (ETDEWEB)

    Peterlin, A

    1982-03-01

    The dynamic viscosity investigation of solutions of long chain polymers in very viscous solvents has definitely shown the existence of the low and high frequency plateau with the gradual transition between them. In both extreme cases the extrapolation of the measured Newtonian viscosities of the plateaus to the infinite dilution yields the limiting intrinsic viscosities. Such a behavior is expected from the dynamic intrinsic viscosity of the necklace model of the linear polymer with finite internal viscosity. The plateau at low frequency shows up in any model of polymer solution. This work shows the constant dynamic intrinsic viscosity in both extreme cases is well reproducible by the necklace model with the internal viscosity acting only between the beads on the same link. 20 references.

  19. Structure of DNA toroids and electrostatic attraction of DNA duplexes

    International Nuclear Information System (INIS)

    Cherstvy, A G

    2005-01-01

    DNA-DNA electrostatic attraction is considered as the driving force for the formation of DNA toroids in the presence of DNA condensing cations. This attraction comes from the DNA helical charge distribution and favours hexagonal toroidal cross-sections. The latter is in agreement with recent cryo-electron microscopy studies on DNA condensed with cobalt hexammine. We treat the DNA-DNA interactions within the modern theory of electrostatic interaction between helical macromolecules. The size and thickness of the toroids is calculated within a simple model; other models of stability of DNA toroids are discussed and compared

  20. Guiding the folding pathway of DNA origami.

    Science.gov (United States)

    Dunn, Katherine E; Dannenberg, Frits; Ouldridge, Thomas E; Kwiatkowska, Marta; Turberfield, Andrew J; Bath, Jonathan

    2015-09-03

    DNA origami is a robust assembly technique that folds a single-stranded DNA template into a target structure by annealing it with hundreds of short 'staple' strands. Its guiding design principle is that the target structure is the single most stable configuration. The folding transition is cooperative and, as in the case of proteins, is governed by information encoded in the polymer sequence. A typical origami folds primarily into the desired shape, but misfolded structures can kinetically trap the system and reduce the yield. Although adjusting assembly conditions or following empirical design rules can improve yield, well-folded origami often need to be separated from misfolded structures. The problem could in principle be avoided if assembly pathway and kinetics were fully understood and then rationally optimized. To this end, here we present a DNA origami system with the unusual property of being able to form a small set of distinguishable and well-folded shapes that represent discrete and approximately degenerate energy minima in a vast folding landscape, thus allowing us to probe the assembly process. The obtained high yield of well-folded origami structures confirms the existence of efficient folding pathways, while the shape distribution provides information about individual trajectories through the folding landscape. We find that, similarly to protein folding, the assembly of DNA origami is highly cooperative; that reversible bond formation is important in recovering from transient misfoldings; and that the early formation of long-range connections can very effectively enforce particular folds. We use these insights to inform the design of the system so as to steer assembly towards desired structures. Expanding the rational design process to include the assembly pathway should thus enable more reproducible synthesis, particularly when targeting more complex structures. We anticipate that this expansion will be essential if DNA origami is to continue its

  1. Forced Translocation of Polymer through Nanopore: Deterministic Model and Simulations

    Science.gov (United States)

    Wang, Yanqian; Panyukov, Sergey; Liao, Qi; Rubinstein, Michael

    2012-02-01

    We propose a new theoretical model of forced translocation of a polymer chain through a nanopore. We assume that DNA translocation at high fields proceeds too fast for the chain to relax, and thus the chain unravels loop by loop in an almost deterministic way. So the distribution of translocation times of a given monomer is controlled by the initial conformation of the chain (the distribution of its loops). Our model predicts the translocation time of each monomer as an explicit function of initial polymer conformation. We refer to this concept as ``fingerprinting''. The width of the translocation time distribution is determined by the loop distribution in initial conformation as well as by the thermal fluctuations of the polymer chain during the translocation process. We show that the conformational broadening δt of translocation times of m-th monomer δtm^1.5 is stronger than the thermal broadening δtm^1.25 The predictions of our deterministic model were verified by extensive molecular dynamics simulations

  2. Polymer models with optimal good-solvent behavior

    Science.gov (United States)

    D'Adamo, Giuseppe; Pelissetto, Andrea

    2017-11-01

    We consider three different continuum polymer models, which all depend on a tunable parameter r that determines the strength of the excluded-volume interactions. In the first model, chains are obtained by concatenating hard spherocylinders of height b and diameter rb (we call them thick self-avoiding chains). The other two models are generalizations of the tangent hard-sphere and of the Kremer-Grest models. We show that for a specific value r* , all models show optimal behavior: asymptotic long-chain behavior is observed for relatively short chains. For r < r* , instead, the behavior can be parametrized by using the two-parameter model, which also describes the thermal crossover close to the θ point. The bonds of the thick self-avoiding chains cannot cross each other, and therefore the model is suited for the investigation of topological properties and for dynamical studies. Such a model also provides a coarse-grained description of double-stranded DNA, so that we can use our results to discuss under which conditions DNA can be considered as a model good-solvent polymer.

  3. Development and production of Lab-on-Chip systems for DNA mapping

    DEFF Research Database (Denmark)

    Østergaard, Peter Friis

    as low as 1:200. The developed polymer systems are tested by conducting two different experiments on DNA. Since such experiments are highly sensitive, efforts have been taken in order to lower the autofluorescence of the devices, resulting in a decrease of the background signal to roughly half...... several nanochannels can be placed parallel to each other, a large number of DNA molecules can be investigated. In the second experiment, mapping is performed on human DNA in nanoslit devices. A fluorescent profile is created by heating the sample up to a temperature, where the DNA is partially denatured....... The fluorescent dye will diffuse away from the denatured regions, and by analysing these black areas, the DNA molecule can be identified and potential mutations can be found. In the nanoslits, the DNA is stretched out via a shear flow, resulting in a stretching of more than 95% of the contour length meaning...

  4. Liquid crystalline order in polymers

    CERN Document Server

    Blumstein, Alexandre

    1978-01-01

    Liquid Crystalline Order in Polymers examines the topic of liquid crystalline order in systems containing rigid synthetic macromolecular chains. Each chapter of the book provides a review of one important area of the field. Chapter 1 discusses scattering in polymer systems with liquid crystalline order. It also introduces the field of liquid crystals. Chapter 2 treats the origin of liquid crystalline order in macromolecules by describing the in-depth study of conformation of such macromolecules in their unassociated state. The chapters that follow describe successively the liquid crystalli

  5. "Green" High-Temperature Polymers

    Science.gov (United States)

    Meador, Michael A.

    1998-01-01

    PMR-15 is a processable, high-temperature polymer developed at the NASA Lewis Research Center in the 1970's principally for aeropropulsion applications. Use of fiber-reinforced polymer matrix composites in these applications can lead to substantial weight savings, thereby leading to improved fuel economy, increased passenger and payload capacity, and better maneuverability. PMR-15 is used fairly extensively in military and commercial aircraft engines components seeing service temperatures as high as 500 F (260 C), such as the outer bypass duct for the F-404 engine. The current world-wide market for PMR-15 materials (resins, adhesives, and composites) is on the order of $6 to 10 million annually.

  6. Quality assurance of polymer concrete

    International Nuclear Information System (INIS)

    Schulz, H.

    1984-01-01

    With polymer concrete, a whole range of organisational and functional measures have to be met in order to assure the required quality with an economic expenditure. Quality assurance begins in the design and does not end in the production, rather includes all fields of the enterprise. The following deals with a particular range of the total complex, the inspection methods for assuring the quality of machine components of polymer concrete, particularly machine tool bases, this being through the control of the raw material, the production and the finished product. (orig.) [de

  7. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu

    2017-04-27

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  8. Directed polymers versus directed percolation

    Science.gov (United States)

    Halpin-Healy, Timothy

    1998-10-01

    Universality plays a central role within the rubric of modern statistical mechanics, wherein an insightful continuum formulation rises above irrelevant microscopic details, capturing essential scaling behaviors. Nevertheless, occasions do arise where the lattice or another discrete aspect can constitute a formidable legacy. Directed polymers in random media, along with its close sibling, directed percolation, provide an intriguing case in point. Indeed, the deep blood relation between these two models may have sabotaged past efforts to fully characterize the Kardar-Parisi-Zhang universality class, to which the directed polymer belongs.

  9. Australian polymer banknote: a review

    Science.gov (United States)

    Wilson, Gerard J.

    1998-04-01

    In 1996 Australia became the first country in the world to have an all-polymer currency in general circulation. Australia's first polymer note was a commemorative note that was issued in January 1988 to celebrate the bicentenary of European settlement. That note was the culmination of almost twenty year's collaboration between the Reserve Bank of Australia and the Commonwealth Scientific and Industrial Research Organisation. This paper traces the development of the Bicentennial Banknote note from its conception at a brain- storming meeting between RBA and CSIRO scientists in 1968 through to its release in 1988.

  10. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu; Tian, Qiwei; Dong, Xinglong; Liu, Zhaohui; Basset, Jean-Marie; Saih, Youssef; Sun, Miao; Xu, Wei; Shaikh, Sohel

    2017-01-01

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  11. Polymer electronics a flexible technology

    CERN Document Server

    Technology, Rapra

    2009-01-01

    The worldwide market for polymer electronic products has been estimated to be worth up to £15 billion by 2015 and the opportunity for new markets could be as high as £125 billion by 2025.'The rapid development of polymer electronics has revealed the possibility for transforming the electronics market by offering lighter, flexible and more cost effective alternatives to conventional materials and products. With applications ranging from printed, flexible conductors and novel semiconductor components to intelligent labels and large area displays and solar panels, products that were previously un

  12. Polymer nanotube nanocomposites: synthesis, properties, and applications

    National Research Council Canada - National Science Library

    Mittal, Vikas

    2010-01-01

    ... in these commercially important areas of polymer technology. It sums up recent advances in nanotube composite synthesis technology, provides basic introduction to polymer nanotubes nanocomposite technology for the readers new to this field, provides valuable...

  13. Organic polymers used at high temperatures

    International Nuclear Information System (INIS)

    1983-01-01

    In this book structure and properties of heat resistant polymers are examined. The more recent industrial polymers are presented. Applications in electronic, electrotechnic, space and energy are reviewed in particular geothermy, well drilling, hydrogen production and nuclear energy [fr

  14. Morphology development in immiscible polymer blends

    NARCIS (Netherlands)

    Cardinaels, R.M.; Moldenaers, P.; Guo, Qipeng

    This chapter discusses the morphology development of immiscible binary polymer blends. It first describes morphology development in droplet-matrix structures, the dynamics of fibrillar structures and cocontinuous structures. The chapter then considers binary immiscible polymer blends, such systems

  15. Diketopyrrolopyrrole polymers for organic solar cells

    NARCIS (Netherlands)

    Li, Wei Wei; Hendriks, K.H.; Wienk, M.M.; Janssen, R.A.J.

    2016-01-01

    Conspectus Conjugated polymers have been extensively studied for application in organic solar cells. In designing new polymers, particular attention has been given to tuning the absorption spectrum, molecular energy levels, crystallinity, and charge carrier mobility to enhance performance. As a

  16. Polymer dynamics: Floored by the rings

    Science.gov (United States)

    McLeish, Tom

    2008-12-01

    The tube model can explain how mutually entangled polymer chains move and interact, but it relies on the loose ends of chains to generate relaxation. Ring polymers have no ends - so how do they relax?

  17. Hybrid polymer-inorganic photovoltaic cells

    NARCIS (Netherlands)

    Beek, W.J.E.; Janssen, R.A.J.; Merhari, L.

    2009-01-01

    Composite materials made from organic conjugated polymers and inorganic semiconductors such as metal oxides attract considerable interest for photovoltaic applications. Hybrid polymer-inorganic solar cells offer the opportunity to combine the beneficial properties of the two materials in charge

  18. New Microlayer and Nanolayer Polymer Composites

    National Research Council Canada - National Science Library

    Baer, E

    2001-01-01

    ... (see attached, interim report (1/1/99 - 12/31/99). (4) High barrier, injection moldable systems have been produced by microlayering a polymer with good water barrier and a polymer with good oxygen barrier...

  19. Modelling anisotropic water transport in polymer composite ...

    Indian Academy of Sciences (India)

    Parameters for Fickian diffusion and polymer relaxation models were determined by .... Water transport process of resin and polymer composite specimens at ..... simulation. ... Kwon Y W and Bang H 1997 Finite element method using matlab.

  20. Nonlinear microrheology and molecular imaging to map microscale deformations of entangled DNA networks

    Science.gov (United States)

    Wu, Tsai-Chin; Anderson, Rae

    We use active microrheology coupled to single-molecule fluorescence imaging to elucidate the microscale dynamics of entangled DNA. DNA naturally exists in a wide range of lengths and topologies, and is often confined in cell nucleui, forming highly concentrated and entangled biopolymer networks. Thus, DNA is the model polymer for understanding entangled polymer dynamics as well as the crowded environment of cells. These networks display complex viscoelastic properties that are not well understood, especially at the molecular-level and in response to nonlinear perturbations. Specifically, how microscopic stresses and strains propagate through entangled networks, and what molecular deformations lead to the network stress responses are unknown. To answer these important questions, we optically drive a microsphere through entangled DNA, perturbing the system far from equilibrium, while measuring the resistive force the DNA exerts on the bead during and after bead motion. We simultaneously image single fluorescent-labeled DNA molecules throughout the network to directly link the microscale stress response to molecular deformations. We characterize the deformation of the network from the molecular-level to the mesoscale, and map the stress propagation throughout the network. We further study the impact of DNA length (11 - 115 kbp) and topology (linear vs ring DNA) on deformation and propagation dynamics, exploring key nonlinear features such as tube dilation and power-law relaxation.

  1. Effective immobilization of DNA for development of polypyrrole nanowires based biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Thi Luyen; Chu, Thi Xuan, E-mail: xuan@itims.edu.vn; Huynh, Dang Chinh; Pham, Duc Thanh; Luu, Thi Hoai Thuong; Mai, Anh Tuan, E-mail: tuan.maianh@hust.edu.vn

    2014-09-30

    Highlights: • Effective technique to immobilize probe DNA to the conducting polymer Polypyrrole nanowires (PPy NWs). • The PPy-NWs were electrochemically synthesized on the surface of the Pt electrodes using gelatin as the soft mold. • The DNA probe sequences were immobilized easily on the PPy NWs/Pt electrode using the adsorption method. • The DNA sensor has a low detection limit. - Abstract: This paper reports an easy technique for immobilization of the DNA to the conducting polymer polypyrrole nanowires (PPy NWs). The nanowires were electrochemically synthesized on the surface of working electrode in the presence of gelatin as a soft mold. The structure of obtained PPy NWs was investigated by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy and Surface Enhanced Raman Spectroscopy (SERS). The DNA strands were directly immobilized on the PPy NWs. The amino groups at the up-end of the PPy nanowires facilitate the linkage with the phosphate groups of the probe DNA. The DNA immobilization and hybridization were characterized by Electrochemical Impedance Spectroscopy (EIS). The initial results show that the sensor responses to 10 pM of DNA sequence in the solution.

  2. DNA-nanoparticle assemblies go organic: Macroscopic polymeric materials with nanosized features

    Directory of Open Access Journals (Sweden)

    Mentovich Elad D

    2012-05-01

    Full Text Available Abstract Background One of the goals in the field of structural DNA nanotechnology is the use of DNA to build up 2- and 3-D nanostructures. The research in this field is motivated by the remarkable structural features of DNA as well as by its unique and reversible recognition properties. Nucleic acids can be used alone as the skeleton of a broad range of periodic nanopatterns and nanoobjects and in addition, DNA can serve as a linker or template to form DNA-hybrid structures with other materials. This approach can be used for the development of new detection strategies as well as nanoelectronic structures and devices. Method Here we present a new method for the generation of unprecedented all-organic conjugated-polymer nanoparticle networks guided by DNA, based on a hierarchical self-assembly process. First, microphase separation of amphiphilic block copolymers induced the formation of spherical nanoobjects. As a second ordering concept, DNA base pairing has been employed for the controlled spatial definition of the conjugated-polymer particles within the bulk material. These networks offer the flexibility and the diversity of soft polymeric materials. Thus, simple chemical methodologies could be applied in order to tune the network's electrical, optical and mechanical properties. Results and conclusions One- two- and three-dimensional networks have been successfully formed. Common to all morphologies is the integrity of the micelles consisting of DNA block copolymer (DBC, which creates an all-organic engineered network.

  3. DNA-nanoparticle assemblies go organic: macroscopic polymeric materials with nanosized features.

    Science.gov (United States)

    Mentovich, Elad D; Livanov, Konstantin; Prusty, Deepak K; Sowwan, Mukules; Richter, Shachar

    2012-05-30

    One of the goals in the field of structural DNA nanotechnology is the use of DNA to build up 2- and 3-D nanostructures. The research in this field is motivated by the remarkable structural features of DNA as well as by its unique and reversible recognition properties. Nucleic acids can be used alone as the skeleton of a broad range of periodic nanopatterns and nanoobjects and in addition, DNA can serve as a linker or template to form DNA-hybrid structures with other materials. This approach can be used for the development of new detection strategies as well as nanoelectronic structures and devices. Here we present a new method for the generation of unprecedented all-organic conjugated-polymer nanoparticle networks guided by DNA, based on a hierarchical self-assembly process. First, microphase separation of amphiphilic block copolymers induced the formation of spherical nanoobjects. As a second ordering concept, DNA base pairing has been employed for the controlled spatial definition of the conjugated-polymer particles within the bulk material. These networks offer the flexibility and the diversity of soft polymeric materials. Thus, simple chemical methodologies could be applied in order to tune the network's electrical, optical and mechanical properties. One- two- and three-dimensional networks have been successfully formed. Common to all morphologies is the integrity of the micelles consisting of DNA block copolymer (DBC), which creates an all-organic engineered network.

  4. Crack propagation along polymer/non-polymer interfaces

    NARCIS (Netherlands)

    Vellinga, Willem-Pier; Fedorov, Alexander; De Hosson, Jeff T.

    2007-01-01

    Mechanisms of the propagation of crack fronts along interfaces between a glassy polymer and metal or glass are discussed. Specifically, the systems studied are Poly-Ethylene Terephthalate (PETG) spin-coated on A1, PETG-glass and PETG hot-pressed on Cr-sputtered glass. Cracks studied propagate in an

  5. Conductivity behaviour of polymer gel electrolytes: Role of polymer

    Indian Academy of Sciences (India)

    Unknown

    of a container that can hold a large amount of solvent and as a result possesses the ... having high value of conductivity results in polymer gel electrolytes. They are ..... the availability of free ions provided by the acid. It gene- rally reaches a ...

  6. Method for bonding a thermoplastic polymer to a thermosetting polymer component

    NARCIS (Netherlands)

    Van Tooren, M.J.L.

    2012-01-01

    The invention relates to a method for bonding a thermoplastic polymer to a thermosetting polymer component, the thermoplastic polymer having a melting temperature that exceeds the curing temperature of the thermosetting polymer. The method comprises the steps of providing a cured thermosetting

  7. The role of radiation in polymer chemistry

    International Nuclear Information System (INIS)

    Du Plessis, T.A.

    1977-10-01

    The very important role which polymer chemistry plays in radiation technology is discussed. The present status of radiation processing and the radiation sources that are used by industry are described. The process by which ionising radiation interacts with vinyl monomers and polymers are treated briefly, and the kinetics and mechanisms of the industrially important radiation processes in the polymer field is discussed. Finally, some of the most important industrial radiation processes related to the field of polymers are pointed out [af

  8. Post polymerization cure shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Hearon, II, Michael Keith; Bearinger, Jane P.

    2017-01-10

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  9. Integration of active and passive polymer optics

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Schøler, Mikkel; Kristensen, Anders

    2007-01-01

    We demonstrate a wafer scale fabrication process for integration of active and passive polymer optics: Polymer DFB lasers and waveguides. Polymer dye DFB lasers are fabricated by combined nanoimprint and photolithography (CNP). The CNP fabrication relies on an UV transparent stamp with nm sized...... wavelength from temperature and refractive index changes in the surroundings is investigated, pointing towards the use of the described fabrication method for on-chip polymer sensor systems....

  10. Polymer Electrolytes for Lithium/Sulfur Batteries

    Directory of Open Access Journals (Sweden)

    The Nam Long Doan

    2012-08-01

    Full Text Available This review evaluates the characteristics and advantages of employing polymer electrolytes in lithium/sulfur (Li/S batteries. The main highlights of this study constitute detailed information on the advanced developments for solid polymer electrolytes and gel polymer electrolytes, used in the lithium/sulfur battery. This includes an in-depth analysis conducted on the preparation and electrochemical characteristics of the Li/S batteries based on these polymer electrolytes.

  11. Recent trends in radiation polymer chemistry

    International Nuclear Information System (INIS)

    Okamura, S.

    1993-01-01

    This book contains five contributions with the following topics: 1. Electron Spin Echo Studies of Free Radicals in Irradiated Polymers (H. Yoshida, T. Ichikawa); 2. Application of Pulse Radiolysis to the Study of Polymers and Polymerizations (M. Ogasawara); 3. Radiation Synthesis of Polymeric Materials for Biomedical and Biochemical Applications (I. Kaetsu); 4. Radiation Effects of Ion Beams on Polymers (S. Tagawa); and 5. Polymer Materials for Fusion Reactors (H. Yamaoka). (orig./MM). 74 figs., 12 tabs

  12. The Recent Developments in Biobased Polymers toward General and Engineering Applications: Polymers that Are Upgraded from Biodegradable Polymers, Analogous to Petroleum-Derived Polymers, and Newly Developed

    OpenAIRE

    Nakajima, Hajime; Dijkstra, Peter; Loos, Katja

    2017-01-01

    The main motivation for development of biobased polymers was their biodegradability, which is becoming important due to strong public concern about waste. Reflecting recent changes in the polymer industry, the sustainability of biobased polymers allows them to be used for general and engineering applications. This expansion is driven by the remarkable progress in the processes for refining biomass feedstocks to produce biobased building blocks that allow biobased polymers to have more versati...

  13. Post polymerization cure shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

    2014-11-11

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  14. SMART POLYMERS: INNOVATIONS IN NOVEL DRUG DELIVERY

    OpenAIRE

    Apoorva Mahajan; Geeta Aggarwal

    2011-01-01

    Smart polymers are attracting the researchers for development of novel drug delivery systems. Importance of smart polymers is rising day by day as these polymers undergo large reversible, physical or chemical changes in response to small changes in the environmental conditions such as pH, temperature, dual- stimuli, light and phase transition. Smart polymers are representing promising means for targeted drug delivery, enhanced drug delivery, gene therapy, actuator stimuli and protein folders....

  15. Irradiation sterilization of semi-crystalline polymers

    International Nuclear Information System (INIS)

    Williams, J.; Dunn, T.; Stannett, V.

    1978-01-01

    A semi-crystalline polymer such as polypropylene, is sterilized by high energy irradiation, with the polymer containing a non-crystalline mobilizing additive which increases the free volume of the polymer, to prevent embrittlement of the polymer during and subsequent to the irradiation. The additive has a density of from 0.6 to 1.9 g/cm 3 and a molecular weight from 100 to 10,000 g/mole

  16. Photodegradation of polymers physical characteristics and applications

    CERN Document Server

    Rabek, Jan F

    1996-01-01

    In this book on physical characteristics and practical aspects of polymer photodegradation Rabek emphasizes the experimental work on the subject. The most important feature of the book is the physical interpretation of polymer degradation, e.g. mechanism of UV/light absorption, formation of excited states, energy transfer mechanism, kinetics, dependence on physical properties of macromolecules and polymer matrices, formation of mechanical defects, practics during environmental ageing. He includes also some aspects of polymer photodegradation in environmental and space condition.

  17. Programmable disorder in random DNA tilings

    Science.gov (United States)

    Tikhomirov, Grigory; Petersen, Philip; Qian, Lulu

    2017-03-01

    Scaling up the complexity and diversity of synthetic molecular structures will require strategies that exploit the inherent stochasticity of molecular systems in a controlled fashion. Here we demonstrate a framework for programming random DNA tilings and show how to control the properties of global patterns through simple, local rules. We constructed three general forms of planar network—random loops, mazes and trees—on the surface of self-assembled DNA origami arrays on the micrometre scale with nanometre resolution. Using simple molecular building blocks and robust experimental conditions, we demonstrate control of a wide range of properties of the random networks, including the branching rules, the growth directions, the proximity between adjacent networks and the size distribution. Much as combinatorial approaches for generating random one-dimensional chains of polymers have been used to revolutionize chemical synthesis and the selection of functional nucleic acids, our strategy extends these principles to random two-dimensional networks of molecules and creates new opportunities for fabricating more complex molecular devices that are organized by DNA nanostructures.

  18. Dye-sensitized solar cell with natural gel polymer electrolytes and f-MWCNT as counter-electrode

    Science.gov (United States)

    Nwanya, A. C.; Amaechi, C. I.; Ekwealor, A. B. C.; Osuji, R. U.; Maaza, M.; Ezema, F. I.

    2015-05-01

    Samples of DSSCs were made with gel polymer electrolytes using agar, gelatin and DNA as the polymer hosts. Anthocyanine dye from Hildegardia barteri flower is used to sensitize the TiO2 electrode, and the spectrum of the dye indicates strong absorptions in the blue region of the solar spectrum. The XRD pattern of the TiO2 shows that the adsorption of the dye did not affect the crystallinity of the electrode. The f-MWCNT indicates graphite structure of the MWCNTs were acid oxidized without significant damage. Efficiencies of 3.38 and 0.1% were obtained using gelatin and DNA gel polymer electrolytes, respectively, for the fabricated dye-sensitized solar cells.

  19. SYNTHESES AND PROPERTIES OF SOME ORGANOSILANE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xinghua; Robert West

    1984-01-01

    Some organosilane polymers with high molecular weights have been synthesized by cocondensation of organosilicon dihalide monomers with sodium metal in toluene. These polymers are both soluble in common solvents and meltable at lower temperatures, and can be molded, cast into films or drawn into fibers. Exposure of the solid polymers to ultraviolet light leads to degradation or crosslinking.

  20. Inorganic polymers and materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sneddon, Larry G.

    2001-01-01

    This DOE-sponsored project was focused on the design, synthesis, characterization, and applications of new types of boron and silicon polymers with a goal of attaining processable precursors to advanced ceramic materials of technological importance. This work demonstrated a viable design strategy for the systematic formation of polymeric precursors to ceramics based on the controlled functionalization of preformed polymers with pendant groups of suitable compositions and crosslinking properties. Both the new dipentylamine-polyborazylene and pinacolborane-hydridopolysilazane polymers, unlike the parent polyborazylene and other polyborosilazanes, are stable as melts and can be easily spun into polymer fibers. Subsequent pyrolyses of these polymer fibers then provide excellent routes to BN and SiNCB ceramic fibers. The ease of synthesis of both polymer systems suggests new hybrid polymers with a range of substituents appended to polyborazylene or polysilazane backbones, as well as other types of preceramic polymers, should now be readily achieved, thereby allowing even greater control over polymer and ceramic properties. This control should now enable the systematic tailoring of the polymers and derived ceramics for use in different technological applications. Other major recent achievements include the development of new types of metal-catalyzed methods needed for the polymerization and modification of inorganic monomers and polymers, and the modification studies of polyvinylsiloxane and related polymers with substituents that enable the formation of single source precursors to high-strength, sintered SiC ceramics.