Protein-Polymer Conjugates: Synthetic Approaches by Controlled Radical Polymerizations & Interesting Applications

PubMed Central

Grover, Gregory N.; Maynard, Heather D.

2011-01-01

Protein-polymer conjugates are of interest to researchers in diverse fields. Attachment of polymers to proteins results in improved pharmacokinetics, which is important in medicine. From an engineering standpoint, conjugates are exciting because they exhibit properties of both the biomolecules and synthetic polymers. This allows the activity of the protein to be altered or tuned, a key aspect in therapeutic design, anchoring conjugates to surfaces, and utilizing these materials for supramolecular self-assembly. Thus, there is broad interest in straightforward synthetic methods to make protein-polymer conjugates. Controlled radical polymerization (CRP) techniques have emerged as excellent strategies to make conjugates because the resulting polymers have narrow molecular weight distributions, targeted molecular weights, and attach to specific sites on proteins. Herein, recent advances in the synthesis and application of protein-polymer conjugates by CRP are highlighted. PMID:21071260

Chain conformations dictate multiscale charge transport phenomena in disordered semiconducting polymers

PubMed Central

Noriega, Rodrigo; Salleo, Alberto; Spakowitz, Andrew J.

2013-01-01

Existing models for the electronic properties of conjugated polymers do not capture the spatial arrangement of the disordered macromolecular chains over which charge transport occurs. Here, we present an analytical and computational description in which the morphology of individual polymer chains is dictated by well-known statistical models and the electronic coupling between units is determined using Marcus theory. The multiscale transport of charges in these materials (high mobility at short length scales, low mobility at long length scales) is naturally described with our framework. Additionally, the dependence of mobility with electric field and temperature is explained in terms of conformational variability and spatial correlation. Our model offers a predictive approach to connecting processing conditions with transport behavior. PMID:24062459

Chain conformations dictate multiscale charge transport phenomena in disordered semiconducting polymers.

PubMed

Noriega, Rodrigo; Salleo, Alberto; Spakowitz, Andrew J

2013-10-08

Existing models for the electronic properties of conjugated polymers do not capture the spatial arrangement of the disordered macromolecular chains over which charge transport occurs. Here, we present an analytical and computational description in which the morphology of individual polymer chains is dictated by well-known statistical models and the electronic coupling between units is determined using Marcus theory. The multiscale transport of charges in these materials (high mobility at short length scales, low mobility at long length scales) is naturally described with our framework. Additionally, the dependence of mobility with electric field and temperature is explained in terms of conformational variability and spatial correlation. Our model offers a predictive approach to connecting processing conditions with transport behavior.

Incorporating functionalized polyethylene glycol lipids into reprecipitated conjugated polymer nanoparticles for bioconjugation and targeted labeling of cells

NASA Astrophysics Data System (ADS)

Kandel, Prakash K.; Fernando, Lawrence P.; Ackroyd, P. Christine; Christensen, Kenneth A.

2011-03-01

We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing.We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing. Electronic supplementary information (ESI) available: Additional TEM data, supplemental light scattering measurements, absorbance and fluorescence emission spectra, and photostability measurements. See DOI: 10.1039/c0nr00746c

Molecular design toward highly efficient photovoltaic polymers based on two-dimensional conjugated benzodithiophene.

PubMed

Ye, Long; Zhang, Shaoqing; Huo, Lijun; Zhang, Maojie; Hou, Jianhui

2014-05-20

As researchers continue to develop new organic materials for solar cells, benzo[1,2-b:4,5-b']dithiophene (BDT)-based polymers have come to the fore. To improve the photovoltaic properties of BDT-based polymers, researchers have developed and applied various strategies leading to the successful molecular design of highly efficient photovoltaic polymers. Novel polymer materials composed of two-dimensional conjugated BDT (2D-conjugated BDT) have boosted the power conversion efficiency of polymer solar cells (PSCs) to levels that exceed 9%. In this Account, we summarize recent progress related to the design and synthesis of 2D-conjugated BDT-based polymers and discuss their applications in highly efficient photovoltaic devices. We introduce the basic considerations for the construction of 2D-conjugated BDT-based polymers and systematic molecular design guidelines. For example, simply modifying an alkoxyl-substituted BDT to form an alkylthienyl-substituted BDT can improve the polymer hole mobilities substantially with little effect on their molecular energy level. Secondly, the addition of a variety of chemical moieties to the polymer can produce a 2D-conjugated BDT unit with more functions. For example, the introduction of a conjugated side chain with electron deficient groups (such as para-alkyl-phenyl, meta-alkoxyl-phenyl, and 2-alkyl-3-fluoro-thienyl) allowed us to modulate the molecular energy levels of 2D-conjugated BDT-based polymers. Through the rational design of BDT analogues such as dithienobenzodithiophene (DTBDT) or the insertion of larger π bridges, we can tune the backbone conformations of these polymers and modulate their photovoltaic properties. We also discuss the influence of 2D-conjugated BDT on polymer morphology and the blends of these polymers with phenyl-C61 (or C71)-butyric acid methyl ester (PCBM). Finally, we summarize the various applications of the 2D-conjugated BDT-based polymers in highly efficient PSC devices. Overall, this Account correlates the molecular structures of the 2D-conjugated BDT-based polymers with their photovoltaic properties. As a result, this Account can guide the molecular design of organic photovoltaic materials and the development of organic materials for other types of optoelectronic devices.

Degradable conjugated polymers for the selective sorting of semiconducting carbon nanotubes

DOEpatents

Gopalan, Padma; Arnold, Michael Scott; Kansiusarulsamy, Catherine Kanimozhi; Brady, Gerald Joseph; Shea, Matthew John

2018-04-10

Conjugated polymers composed of bi-pyridine units linked to 9,9-dialkyl fluorenyl-2,7-diyl units via imine linkages along the polymer backbone are provided. Also provided are semiconducting single-walled carbon nanotubes coated with the conjugated polymers and methods of sorting and separating s-SWCNTs from a sample comprising a mixture of s-SWCNTs and metallic single-walled carbon nanotubes using the conjugated polymers.

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

PubMed

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.

Diketopyrrolopyrrole-based Conjugated Polymers Bearing Branched Oligo(Ethylene Glycol) Side Chains for Photovoltaic Devices.

PubMed

Chen, Xingxing; Zhang, Zijian; Ding, Zicheng; Liu, Jun; Wang, Lixiang

2016-08-22

Conjugated polymers are essential for solution-processable organic opto-electronic devices. In contrast to the great efforts on developing new conjugated polymer backbones, research on developing side chains is rare. Herein, we report branched oligo(ethylene glycol) (OEG) as side chains of conjugated polymers. Compared with typical alkyl side chains, branched OEG side chains endowed the resulting conjugated polymers with a smaller π-π stacking distance, higher hole mobility, smaller optical band gap, higher dielectric constant, and larger surface energy. Moreover, the conjugated polymers with branched OEG side chains exhibited outstanding photovoltaic performance in polymer solar cells. A power conversion efficiency of 5.37 % with near-infrared photoresponse was demonstrated and the device performance could be insensitive to the active layer thickness. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Helically assembled π-conjugated polymers with circularly polarized luminescence.

PubMed

Watanabe, Kazuyoshi; Akagi, Kazuo

2014-08-01

We review the recent progress in the field of helically assembled π -conjugated polymers, focusing on aromatic conjugated polymers with interchain helical π -stacking that exhibit circularly polarized luminescence (CPL). In Part 1, we discuss optically active polymers with white-colored CPL and the amplification of the circular polarization through liquid crystallinity. In Part 2, we focus on the stimuli-responsive CPL that results from changes in the conformation and aggregation state of π -conjugated molecules and polymers. In Part 3, we discuss the self-assembly of achiral cationic π -conjugated polymers into circularly polarized luminescent supramolecular nanostructures with the aid of other chiral molecules.

Femtosecond Pump-Push-Probe and Pump-Dump-Probe Spectroscopy of Conjugated Polymers: New Insight and Opportunities.

PubMed

Kee, Tak W

2014-09-18

Conjugated polymers are an important class of soft materials that exhibit a wide range of applications. The excited states of conjugated polymers, often referred to as excitons, can either deactivate to yield the ground state or dissociate in the presence of an electron acceptor to form charge carriers. These interesting properties give rise to their luminescence and the photovoltaic effect. Femtosecond spectroscopy is a crucial tool for studying conjugated polymers. Recently, more elaborate experimental configurations utilizing three optical pulses, namely, pump-push-probe and pump-dump-probe, have been employed to investigate the properties of excitons and charge-transfer states of conjugated polymers. These studies have revealed new insight into femtosecond torsional relaxation and detrapping of bound charge pairs of conjugated polymers. This Perspective highlights (1) the recent achievements by several research groups in using pump-push-probe and pump-dump-probe spectroscopy to study conjugated polymers and (2) future opportunities and potential challenges of these techniques.

Fused electron deficient semiconducting polymers for air stable electron transport.

PubMed

Onwubiko, Ada; Yue, Wan; Jellett, Cameron; Xiao, Mingfei; Chen, Hung-Yang; Ravva, Mahesh Kumar; Hanifi, David A; Knall, Astrid-Caroline; Purushothaman, Balaji; Nikolka, Mark; Flores, Jean-Charles; Salleo, Alberto; Bredas, Jean-Luc; Sirringhaus, Henning; Hayoz, Pascal; McCulloch, Iain

2018-01-29

Conventional semiconducting polymer synthesis typically involves transition metal-mediated coupling reactions that link aromatic units with single bonds along the backbone. Rotation around these bonds contributes to conformational and energetic disorder and therefore potentially limits charge delocalisation, whereas the use of transition metals presents difficulties for sustainability and application in biological environments. Here we show that a simple aldol condensation reaction can prepare polymers where double bonds lock-in a rigid backbone conformation, thus eliminating free rotation along the conjugated backbone. This polymerisation route requires neither organometallic monomers nor transition metal catalysts and offers a reliable design strategy to facilitate delocalisation of frontier molecular orbitals, elimination of energetic disorder arising from rotational torsion and allowing closer interchain electronic coupling. These characteristics are desirable for high charge carrier mobilities. Our polymers with a high electron affinity display long wavelength NIR absorption with air stable electron transport in solution processed organic thin film transistors.

Thermally switchable dielectrics

DOEpatents

Dirk, Shawn M.; Johnson, Ross S.

2013-04-30

Precursor polymers to conjugated polymers, such as poly(phenylene vinylene), poly(poly(thiophene vinylene), poly(aniline vinylene), and poly(pyrrole vinylene), can be used as thermally switchable capacitor dielectrics that fail at a specific temperature due to the non-conjugated precursor polymer irreversibly switching from an insulator to the conjugated polymer, which serves as a bleed resistor. The precursor polymer is a good dielectric until it reaches a specific temperature determined by the stability of the leaving groups. Conjugation of the polymer backbone at high temperature effectively disables the capacitor, providing a `built-in` safety mechanism for electronic devices.

Controlled Radical Polymerization as an Enabling Approach for the Next Generation of Protein-Polymer Conjugates.

PubMed

Pelegri-O'Day, Emma M; Maynard, Heather D

2016-09-20

Protein-polymer conjugates are unique constructs that combine the chemical properties of a synthetic polymer chain with the biological properties of a biomacromolecule. This often leads to improved stabilities, solubilities, and in vivo half-lives of the resulting conjugates, and expands the range of applications for the proteins. However, early chemical methods for protein-polymer conjugation often required multiple polymer modifications, which were tedious and low yielding. To solve these issues, work in our laboratory has focused on the development of controlled radical polymerization (CRP) techniques to improve synthesis of protein-polymer conjugates. Initial efforts focused on the one-step syntheses of protein-reactive polymers through the use of functionalized initiators and chain transfer agents. A variety of functional groups such as maleimide and pyridyl disulfide could be installed with high end-group retention, which could then react with protein functional groups through mild and biocompatible chemistries. While this grafting to method represented a significant advance in conjugation technique, purification and steric hindrance between large biomacromolecules and polymer chains often led to low conjugation yields. Therefore, a grafting from approach was developed, wherein a polymer chain is grown from an initiating site on a functionalized protein. These conjugates have demonstrated improved homogeneity, characterization, and easier purification, while maintaining protein activity. Much of this early work utilizing CRP techniques focused on polymers made up of biocompatible but nonfunctional monomer units, often containing oligoethylene glycol meth(acrylate) or N-isopropylacrylamide. These branched polymers have significant advantages compared to the historically used linear poly(ethylene glycols) including decreased viscosities and thermally responsive behavior, respectively. Recently, we were motivated to use CRP techniques to develop polymers with rationally designed and functional biological properties for conjugate preparation. Specifically, two families of saccharide-inspired polymers were developed for stabilization and activation of therapeutic biomolecules. A series of polymers with trehalose side-chains and vinyl backbones were prepared and used to stabilize proteins against heat and lyophilization stress as both conjugates and additives. These materials, which combine properties of osmolytes with nonionic surfactants, have significant potential for in vivo therapeutic use. Additionally, polymers that mimic the structure of the naturally occurring polysaccharide heparin were prepared. These polymers contained negatively charged sulfonate groups and imparted stabilization to a heparin-binding growth factor after conjugation. A screen of other sulfonated polymers led to the development of a polymer with improved heparin mimesis, enhancing both stability and activity of the protein to which it was attached. Chemical improvements over the past decade have enabled the preparation of a diverse set of protein-polymer conjugates by controlled polymerization techniques. Now, the field should thoroughly explore and expand both the range of polymer structures and also the applications available to protein-polymer conjugates. As we move beyond medicine toward broader applications, increased collaboration and interdisciplinary work will result in the further development of this exciting field.

Multifunctional Diketopyrrolopyrrole-Based Conjugated Polymers with Perylene Bisimide Side Chains.

PubMed

Li, Cheng; Yu, Changshi; Lai, Wenbin; Liang, Shijie; Jiang, Xudong; Feng, Guitao; Zhang, Jianqi; Xu, Yunhua; Li, Weiwei

2017-11-24

Two conjugated polymers based on diketopyrrolopyrrole (DPP) in the main chain with different content of perylene bisimide (PBI) side chains are developed. The influence of PBI side chain on the photovoltaic performance of these DPP-based conjugated polymers is systematically investigated. This study suggests that the PBI side chains can not only alter the absorption spectrum and energy level but also enhance the crystallinity of conjugated polymers. As a result, such polymers can act as electron donor, electron acceptor, and single-component active layer in organic solar cells. These findings provide a new guideline for the future molecular design of multifunctional conjugated polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Scattering from Colloid-Polymer Conjugates with Excluded Volume Effect

DOE PAGES

Li, Xin; Sanchez-Diaz, Luis E.; Smith, Gregory Scott; ...

2015-01-13

This work presents scattering functions of conjugates consisting of a colloid particle and a self-avoiding polymer chain as a model for protein-polymer conjugates and nanoparticle-polymer conjugates in solution. The model is directly derived from the two-point correlation function with the inclusion of excluded volume effects. The dependence of the calculated scattering function on the geometric shape of the colloid and polymer stiffness is investigated. The model is able to describe the experimental scattering signature of the solutions of suspending hard particle-polymer conjugates and provide additional conformational information. This model explicitly elucidates the link between the global conformation of a conjugatemore » and the microstructure of its constituent components.« less

Chain conformations and phase behavior of conjugated polymers.

PubMed

Kuei, Brooke; Gomez, Enrique D

2016-12-21

Conjugated polymers may play an important role in various emerging optoelectronic applications because they combine the chemical versatility of organic molecules and the flexibility, stretchability and toughness of polymers with semiconducting properties. Nevertheless, in order to achieve the full potential of conjugated polymers, a clear description of how their structure, morphology, and macroscopic properties are interrelated is needed. We propose that the starting point for understanding conjugated polymers includes understanding chain conformations and phase behavior. Efforts to predict and measure the persistence length have significantly refined our intuition of the chain stiffness, and have led to predictions of nematic-to-isotropic transitions. Exploring mixing between conjugated polymers and small molecules or other polymers has demonstrated tremendous advancements in attaining the needed properties for various optoelectronic devices. Current efforts continue to refine our knowledge of chain conformations and phase behavior and the factors that influence these properties, thereby providing opportunities for the development of novel optoelectronic materials based on conjugated polymers.

Developing conjugated polymers with high electron affinity by replacing a C-C unit with a B←N unit.

PubMed

Dou, Chuandong; Ding, Zicheng; Zhang, Zijian; Xie, Zhiyuan; Liu, Jun; Wang, Lixiang

2015-03-16

The key parameters of conjugated polymers are lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels. Few approaches can simultaneously lower LUMO and HOMO energy levels of conjugated polymers to a large extent (>0.5 eV). Disclosed herein is a novel strategy to decrease both LUMO and HOMO energy levels of conjugated polymers by about 0.6 eV through replacement of a C-C unit by a B←N unit. The replacement makes the resulting polymer transform from an electron donor into an electron acceptor, and is proven by fluorescence quenching experiments and the photovoltaic response. This work not only provides an effective approach to tune the LUMO/HOMO energy levels of conjugated polymers, but also uses organic boron chemistry as a new toolbox to develop conjugated polymers with high electron affinity for polymer optoelectronic devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Disordered organic electronic materials based on non-benzenoid 1,6-methano[10]annulene rings

DOEpatents

Tovar, John D; Streifel, Benjamin C; Peart, Patricia A

2014-10-07

Conjugated polymers and small molecules including the nonplanar aromatic 1,6-methano[10]annulene ring structure along with aromatic subunits, such as diketopyrrolopyrrole, and 2,1,3-benzothiadiazole, substituted with alkyl chains in a "Tail In," "Tail Out," or "No Tail" regiochemistry are disclosed.

Recent advances in conjugated polymers for light emitting devices.

PubMed

Alsalhi, Mohamad Saleh; Alam, Javed; Dass, Lawrence Arockiasamy; Raja, Mohan

2011-01-01

A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review.

Recent Advances in Conjugated Polymers for Light Emitting Devices

PubMed Central

AlSalhi, Mohamad Saleh; Alam, Javed; Dass, Lawrence Arockiasamy; Raja, Mohan

2011-01-01

A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review. PMID:21673938

Preparation and characterization of conjugated polymers made by postpolymerization reactions of alternating polyketones.

PubMed

Cheng, Chen; Guironnet, Damien; Barborak, James; Brookhart, Maurice

2011-06-29

Conjugated polymers possessing a poly(2,5-dimethylene-2,5-dihydrofuran) backbone were prepared through postpolymerization reaction of styrenic polyketones with bromine in one-pot reactions. The modification is proposed to proceed via condensation of two repeating units to form a fully characterized polymer with a poly(2,5-dimethylenetetrahydrofuran) backbone. Subsequent bromination and elimination of HBr yield a polymer with a fully conjugated carbon backbone. The new conjugated polymers were characterized by NMR, IR, and UV-vis spectroscopies and by CV. These polymers have strong absorption in the visible region, with the absorption peaks shifted to the NIR region upon doping with acids. The ease of the synthesis of the starting polyketone and of the modifications allows large-scale preparation of those conjugated polymers.

Enhancing performing characteristics of organic semiconducting films by improved solution processing

DOEpatents

Bazan, Guillermo C; Moses, Daniel; Peet, Jeffrey; Heeger, Alan J

2014-05-13

Improved processing methods for enhanced properties of conjugated polymer films are disclosed, as well as the enhanced conjugated polymer films produced thereby. Addition of low molecular weight alkyl-containing molecules to solutions used to form conjugated polymer films leads to improved photoconductivity and improvements in other electronic properties. The enhanced conjugated polymer films can be used in a variety of electronic devices, such as solar cells and photodiodes.

Effects of the Substituents of Boron Atoms on Conjugated Polymers Containing B←N Units.

PubMed

Liu, Jun; Wang, Tao; Dou, Chuandong; Wang, Lixiang

2018-06-15

Organoboron chemistry is a new tool to tune the electronic structures and properties of conjugated polymers, which are important for applications in organic opto-electronic devices. To investigate the effects of substituents of boron atoms on conjugated polymers, we synthesized three conjugated polymers based on double B←N bridged bipyridine (BNBP) with various substituents on the boron atoms. By changing the substituents from four phenyl groups and two phenyl groups/two fluorine atoms to four fluorine atoms, the BNBP-based polymers show the blue-shifted absorption spectra, decreased LUMO/HOMO energy levels and enhanced electron affinities, as well as the increased electron mobilities. Moreover, these BNBP-based polymers can be used as electron acceptors for all-polymer solar cells. These results demonstrate that the substituents of boron atoms can effectively modulate the electronic properties and applications of conjugated polymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Generation of conductivity through transfer charge properties, for polyesters and polyamides with characteristic functional groups

NASA Astrophysics Data System (ADS)

Gonzalez, Carmen; Tagle, Luis Hernan; Terraza, Claudio A.; Barriga, Andres; Cabrera, A. L.; Volkmann, Ulrich G.

2011-03-01

Electro-optic properties of σ -conjugated polymers, as polysilylene; are associated with electron conjugation in the silicon atom, which allows a significant delocalization of electrons along of the chain. Thus, the conductivity is intimately connected to the mobility of charge carriers, which in turn depends on the structure and morphology of the system. We report the characterization of polyesters (PEFs) and polyamides (PAFs). Film thicknesses were obtained by ellipsometry. The vibration frequencies of the groups were determined by FT-IR and corroborated by Raman spectroscopy. Structural information was obtained from X-Ray diffraction (XRD). The structural and surface morphology were studied by scanning electron microscope (SEM). Electrical conductivity of the polymers was measured before and after exposure to iodine vapor, for films of different thicknesses. Morphological differentiation was studied by energy dispersive microscopy (EDX), showing a regular distribution of iodine within the polymer. Preliminary conductivity measurements showed adverse effects when oxidation of the polymer films is induced These effects are related to a certain grade of disorder within the system

Molecular Engineering for Mechanically Resilient and Stretchable Electronic Polymers and Composites

DTIC Science & Technology

2016-06-08

conjugated polymers and composites by analysis of the structural determinants of the mechanical properties. We developed coarse-grained molecular...dynamics simulations that predicted the mechanical properties of conjugated polymers and polymer -fullerene composites. We elucidated the mechanical...We also determined the effect of cyclic stretching on the microstructure and mechanical properties of conjugated polymers . We used many of

Influence of the Surfactant Structure on Photoluminescent π-Conjugated Polymer Nanoparticles: Interfacial Properties and Protein Binding.

PubMed

Urbano, Laura; Clifton, Luke; Ku, Hoi Ki; Kendall-Troughton, Hannah; Vandera, Kalliopi-Kelli A; Matarese, Bruno F E; Abelha, Thais; Li, Peixun; Desai, Tejal; Dreiss, Cécile A; Barker, Robert D; Green, Mark A; Dailey, Lea Ann; Harvey, Richard D

2018-05-17

π-Conjugated polymer nanoparticles (CPNs) are under investigation as photoluminescent agents for diagnostics and bioimaging. To determine whether the choice of surfactant can improve CPN properties and prevent protein adsorption, five nonionic polyethylene glycol alkyl ether surfactants were used to produce CPNs from three representative π-conjugated polymers. The surfactant structure did not influence size or yield, which was dependent on the nature of the conjugated polymer. Hydrophobic interaction chromatography, contact angle, quartz crystal microbalance, and neutron reflectivity studies were used to assess the affinity of the surfactant to the conjugated polymer surface and indicated that all surfactants were displaced by the addition of a model serum protein. In summary, CPN preparation methods which rely on surface coating of a conjugated polymer core with amphiphilic surfactants may produce systems with good yields and colloidal stability in vitro, but may be susceptible to significant surface alterations in physiological fluids.

Synthesis and Characterization of SF-PPV-I

NASA Technical Reports Server (NTRS)

Wang, Y.; Fan, Z.; Taft, C.; Sun, S.

2001-01-01

Conjugated electro-active polymers find their potential applications in developing variety inexpensive and flexible shaped electronic and photonic devices, such as photovoltaic or photo/electro light emitting devices. In many of these opto-electronic polymeric materials, certain electron rich donors and electron deficient acceptors are needed in order to fine-tune the electronic or photonic properties of the desired materials and structures. While many donor type of conjugated polymers have been widely studied and developed in the past decades, there are relatively fewer acceptor type of conjugated polymers have been developed. Key acceptor type conjugated polymers developed so far include C60 and CN-PPV, and each has its limitations. Due to the complexity and diversity of variety future electronic materials and structural needs, alternative and synthetically amenable acceptor conjugated polymers need to be developed. In this paper, we present the synthesis and characterization of a new acceptor conjugated polymer, a sulfone derivatized polyphenylenevinylene "SF-PPV".

Controlling Molecular Ordering in Solution-State Conjugated Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Jiahua; Han, Youngkyu; Kumar, Rajeev

Rationally encoding molecular interactions that can control the assembly structure and functional expression in solution of conjugated polymers holds great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution,more » we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.« less

Controlling Molecular Ordering in Solution-State Conjugated Polymers

DOE PAGES

Zhu, Jiahua; Han, Youngkyu; Kumar, Rajeev; ...

2015-07-17

Rationally encoding molecular interactions that can control the assembly structure and functional expression in solution of conjugated polymers holds great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution,more » we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.« less

Conjugated polymer zwitterions and solar cells comprising conjugated polymer zwitterions

DOEpatents

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 C_3-30 arylene or heteroarylene group; L is independently at each occurrence a divalent C_1-16 alkylene group, C_6-30arylene 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.

Polymer therapeutics: concepts and applications.

PubMed

Haag, Rainer; Kratz, Felix

2006-02-13

Polymer therapeutics encompass polymer-protein conjugates, drug-polymer conjugates, and supramolecular drug-delivery systems. Numerous polymer-protein conjugates with improved stability and pharmacokinetic properties have been developed, for example, by anchoring enzymes or biologically relevant proteins to polyethylene glycol components (PEGylation). Several polymer-protein conjugates have received market approval, for example the PEGylated form of adenosine deaminase. Coupling low-molecular-weight anticancer drugs to high-molecular-weight polymers through a cleavable linker is an effective method for improving the therapeutic index of clinically established agents, and the first candidates have been evaluated in clinical trials, including, N-(2-hydroxypropyl)methacrylamide conjugates of doxorubicin, camptothecin, paclitaxel, and platinum(II) complexes. Another class of polymer therapeutics are drug-delivery systems based on well-defined multivalent and dendritic polymers. These include polyanionic polymers for the inhibition of virus attachment, polycationic complexes with DNA or RNA (polyplexes), and dendritic core-shell architectures for the encapsulation of drugs. In this Review an overview of polymer therapeutics is presented with a focus on concepts and examples that characterize the salient features of the drug-delivery systems.

Conjugated Polymers: Catalysts for Photocatalytic Hydrogen Evolution.

PubMed

Zhang, Guigang; Lan, Zhi-An; Wang, Xinchen

2016-12-19

Conjugated polymers, comprising fully π-conjugated systems, present a new generation of heterogeneous photocatalysts for solar-energy utilization. They have three key features, namely robustness, nontoxicity, and visible-light activity, for photocatalytic processes, thus making them appealing candidates for scale-up. Presented in this Minireview, is a brief summary on the recent development of various promising polymer photocatalysts for hydrogen evolution from aqueous solutions, including linear polymers, planarized polymers, triazine/heptazine polymers, and other related organic conjugated semiconductors, with a particular focus on the rational manipulation in the composition, architectures, and optical and electronic properties that are relevant to photophysical and photochemical properties. Some future trends and prospects for organic conjugated photocatalysts in artificial photosynthesis, by water splitting, are also envisaged. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conjugated Polymers for Flexible Energy Harvesting and Storage.

PubMed

Zhang, Zhitao; Liao, Meng; Lou, Huiqing; Hu, Yajie; Sun, Xuemei; Peng, Huisheng

2018-03-01

Since the discovery of conjugated polymers in the 1970s, they have attracted considerable interest in light of their advantages of having a tunable bandgap, high electroactivity, high flexibility, and good processability compared to inorganic conducting materials. The above combined advantages make them promising for effective energy harvesting and storage, which have been widely studied in recent decades. Herein, the key advancements in the use of conjugated polymers for flexible energy harvesting and storage are reviewed. The synthesis, structure, and properties of conjugated polymers are first summarized. Then, their applications in flexible polymer solar cells, thermoelectric generators, supercapacitors, and lithium-ion batteries are described. The remaining challenges are then discussed to highlight the future direction in the development of conjugated polymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Characterization of Bioactive Tamoxifen-conjugated Polymers

PubMed Central

Rickert, Emily L.; Trebley, Joseph P.; Peterson, Anton C.; Morrell, Melinda M.; Weatherman, Ross V.

2008-01-01

Macromolecular conjugates of tamoxifen could perhaps be used to circumvent some of the limitations of the extensively used breast cancer drug. To test the feasibility of these conjugates, a 4-hydroxytamoxifen analog was conjugated to a diaminoalkyl linker and then conjugated to activated esters of a poly(methacrylic acid) polymer synthesized by atom transfer radical polymerization. A polymer conjugated to the 4-hydroxytamoxifen analog with a six carbon linker showed high affinity for both estrogen receptor alpha and estrogen receptor beta and potent antagonism of the estrogen receptor in cell-based transcriptional reporter assays. These results suggest that the conjugation of 4-hydroxytamoxifen to a polymer results in a macromolecular conjugate that can display ligand in a manner that can be recognized by estrogen receptor and still act as a potent antiestrogen in cells. PMID:17929966

Nanostructured conjugated polymers in chemical sensors: synthesis, properties and applications.

PubMed

Correa, D S; Medeiros, E S; Oliveira, J E; Paterno, L G; Mattoso, Luiz C

2014-09-01

Conjugated polymers are organic materials endowed with a π-electron conjugation along the polymer backbone that present appealing electrical and optical properties for technological applications. By using conjugated polymeric materials in the nanoscale, such properties can be further enhanced. In addition, the use of nanostructured materials makes possible miniaturize devices at the micro/nano scale. The applications of conjugated nanostructured polymers include sensors, actuators, flexible displays, discrete electronic devices, and smart fabric, to name a few. In particular, the use of conjugated polymers in chemical and biological sensors is made feasible owning to their sensitivity to the physicochemical conditions of its surrounding environment, such as chemical composition, pH, dielectric constant, humidity or even temperature. Subtle changes in these conditions bring about variations on the electrical (resistivity and capacitance), optical (absorptivity, luminescence, etc.), and mechanical properties of the conjugated polymer, which can be precisely measured by different experimental methods and ultimately associated with a specific analyte and its concentration. The present review article highlights the main features of conjugated polymers that make them suitable for chemical sensors. An especial emphasis is given to nanostructured sensors systems, which present high sensitivity and selectivity, and find application in beverage and food quality control, pharmaceutical industries, medical diagnosis, environmental monitoring, and homeland security, and other applications as discussed throughout this review.

Bis-polymer lipid-peptide conjugates and nanoparticles thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Ting; Dong, He; Shu, Jessica

The present invention provides bis-polymer lipid-peptide conjugates containing a hydrophobic block and headgroup containing a helical peptide and two polymer blocks. The conjugates can self-assemble to form helix bundle subunits, which in turn assemble to provide micellar nanocarriers for drug cargos and other agents. Particles containing the conjugates and methods for forming the particles are also disclosed.

Personal Cooling Fabric Based on Polymeric Thermoelectrics

DTIC Science & Technology

2016-07-28

weight organic materials. Furthermore, p- and n-doped conjugated polymers with high electrical conductivity were discovered over two decades ago...fully conjugated PPV polymer MEH-PPV with SWCNT provided films with the highest conductivity while maintaining relatively unchanged Seebeck...Geise, H. J., Synthesis of Electrically Conducting Copolymers with Short Alternating Conjugated and Non- conjugated Blocks. Polymer 1994, 35, (2), 391-397.

Tuning the entropic spring to dictate order and functionality in polymer conjugated peptide biomaterials

NASA Astrophysics Data System (ADS)

Keten, Sinan

Hybrid peptide-polymer conjugates have the potential to combine the advantages of natural proteins and synthetic polymers, resulting in biomaterials with improved stability, controlled assembly, and tailored functionalities. However, the effect of polymer conjugation on peptide structural organization and functionality, along with the behavior of polymers at the interface with biomolecules remain to be fully understood. This talk will summarize our recent efforts towards establishing a modeling framework to design entropic forces in helix-polymer conjugates and polymer-conjugated peptide nanotubes to achieve hierarchical self-assembling systems with predictable order. The first part of the talk will discuss how self-assembly principles found in biology, combined with polymer physics concepts can be used to create artificial membranes that mimic certain features of ion channels. Thermodynamics and kinetics aspects of self-assembly and how it governs the growth and stacking sequences of peptide nanotubes will be discussed, along with its implications for nanoscale transport. The second part of the talk will review advances related to modeling polymer conjugated coiled coils at relevant length and time scales. Atomistic simulations combined with sampling techniques will be presented to discuss the energy landscapes governing coiled-coil stability, revealing cascades of events governing disassembly. This will be followed by a discussion of mechanisms through which polymers can stabilize small proteins, such as shielding of solvents, and how specific peptide sequences can reciprocate by altering polymer conformations. Correlations between mechanical and thermal stability of peptides will be discussed. Finally, coarse-grained simulations will provide insight into how the location of polymer attachment changes entropic forces and higher-level organization in helix bundle assemblies. Our findings set the stage for a materials-by-design capability towards dictating complex topologies of polymer-peptide conjugate systems.

Nanoparticles of conjugated polymers prepared from phase-separated films of phospholipids and polymers for biomedical applications.

PubMed

Yoon, Jungju; Kwag, Jungheon; Shin, Tae Joo; Park, Joonhyuck; Lee, Yong Man; Lee, Yebin; Park, Jonghyup; Heo, Jung; Joo, Chulmin; Park, Tae Jung; Yoo, Pil J; Kim, Sungjee; Park, Juhyun

2014-07-09

Phase separation in films of phospholipids and conjugated polymers results in nanoassemblies because of a difference in the physicochemical properties between the hydrophobic polymers and the polar lipid heads, together with the comparable polymer side-chain lengths to lipid tail lengths, thus producing nanoparticles of conjugated polymers upon disassembly in aqueous media by the penetration of water into polar regions of the lipid heads. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enzyme linked immunoassay with stabilized polymer saccharide enzyme conjugates

DOEpatents

Callstrom, Matthew R.; Bednarski, Mark D.; Gruber, Patrick R.

1997-01-01

An improvement in enzyme linked immunoassays is disclosed wherein the enzyme is in the form of a water soluble polymer saccharide conjugate which is stable in hostile environments. The conjugate comprises the enzyme which is linked to the polymer at multiple points through saccharide linker groups.

Conjugated polymers: Watching polymers dance

NASA Astrophysics Data System (ADS)

Rothberg, Lewis

2011-06-01

Single-molecule spectroscopy allows fluctuations of conjugated polymer conformation to be monitored during solvent vapour annealing. Dramatic changes in fluorescence behaviour are observed and interpreted in terms of transformations between extended and collapsed polymer geometries.

p-π Conjugated Polymers Based on Stable Triarylborane with n-Type Behavior in Optoelectronic Devices.

PubMed

Meng, Bin; Ren, Yi; Liu, Jun; Jäkle, Frieder; Wang, Lixiang

2018-02-19

p-π conjugation with embedded heteroatoms offers unique opportunities to tune the electronic structure of conjugated polymers. An approach is presented to form highly electron-deficient p-π conjugated polymers based on triarylboranes, demonstrate their n-type behavior, and explore device applications. By combining alternating [2,4,6-tris(trifluoromethyl)phenyl]di(thien-2-yl)borane (FBDT) and electron-deficient isoindigo (IID)/pyridine-flanked diketopyrrolopyrrole (DPPPy) units, we achieve low-lying lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels, high electron mobilities, and broad absorptions in the visible region. All-polymer solar cells with these polymers as electron acceptors exhibit encouraging photovoltaic performance with power conversion efficiencies of up to 2.83 %. These results unambiguously prove the n-type behavior and demonstrate the photovoltaic applications of p-π conjugated polymers based on triarylborane. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Excited-State Complexes of Conjugated Polymers: Novel Photophysical Processes and Optoelectronic Materials.

DTIC Science & Technology

1995-03-20

corresponding excited-state complexes were only recently discovered. The results of our extensive studies of intermolecular excimers and exciplexes of many...the luminescence of conjugated polymers. The luminescence and charge photogeneration in exciplexes of conjugated polymers with donor triarylamines will also be presented. jg

Enzyme linked immunoassay with stabilized polymer saccharide enzyme conjugates

DOEpatents

Callstrom, M.R.; Bednarski, M.D.; Gruber, P.R.

1997-11-25

An improvement in enzyme linked immunoassays is disclosed wherein the enzyme is in the form of a water soluble polymer saccharide conjugate which is stable in hostile environments. The conjugate comprises the enzyme which is linked to the polymer at multiple points through saccharide linker groups. 19 figs.

Design of Stomach Acid-Stable and Mucin-Binding Enzyme Polymer Conjugates.

PubMed

Cummings, Chad S; Campbell, Alan S; Baker, Stefanie L; Carmali, Sheiliza; Murata, Hironobu; Russell, Alan J

2017-02-13

The reduced immunogenicity and increased stability of protein-polymer conjugates has made their use in therapeutic applications particularly attractive. However, the physicochemical interactions between polymer and protein, as well as the effect of this interaction on protein activity and stability, are still not fully understood. In this work, polymer-based protein engineering was used to examine the role of polymer physicochemical properties on the activity and stability of the chymotrypsin-polymer conjugates and their degree of binding to intestinal mucin. Four different chymotrypsin-polymer conjugates, each with the same polymer density, were synthesized using "grafting-from" atom transfer radical polymerization. The influence of polymer charge on chymotrypsin-polymer conjugate mucin binding, bioactivity, and stability in stomach acid was determined. Cationic polymers covalently attached to chymotrypsin showed high mucin binding, while zwitterionic, uncharged, and anionic polymers showed no mucin binding. Cationic polymers also increased chymotrypsin activity from pH 6-8, while zwitterionic polymers had no effect, and uncharged and anionic polymers decreased enzyme activity. Lastly, cationic polymers decreased the tendency of chymotrypsin to structurally unfold at extremely low pH, while uncharged and anionic polymers induced unfolding more quickly. We hypothesized that when polymers are covalently attached to the surface of a protein, the degree to which those polymers interact with the protein surface is the predominant determinant of whether the polymer will stabilize or inactivate the protein. Preferential interactions between the polymer and the protein lead to removal of water from the surface of the protein, and this, we believe, inactivates the enzyme.

Simulation Studies of LCST-like Phase Transitions in Elastin-like Polypeptides (ELPs) and Conjugates of ELP with Rigid Macromolecules

NASA Astrophysics Data System (ADS)

Condon, Joshua; Martin, Tyler; Jayaraman, Arthi

We use atomistic (AA) and coarse-grained (CG) molecular dynamics simulations to elucidate the thermodynamic driving forces governing lower critical solution temperature (LCST)-like phase transition exhibited by elastin-like peptides (ELPs) and conjugates of ELP with other macromolecules. In the AA simulations, we study ELP oligomers in explicit water, and mark the transition as the temperature at which they undergo a change in ``hydration'' state. While AA simulations are restricted to small systems of short ELPs and do not capture the chain aggregation observed in experiments of ELPs, they guide the phenomenological CG model development by highlighting the solvent induced polymer-polymer effective interactions with changing temperature. In the CG simulations, we capture the LCST polymer aggregation by increasing polymer-polymer effective attractive interactions in an implicit solvent. We examine the impact of conjugating a block of LCST polymer to another rigid unresponsive macromolecular block on the LCST-like transition. We find that when multiple LCST polymers are conjugated to a rigid polymer block, increased crowding of the LCST polymers shifts the onset of chain aggregation to smaller effective polymer-polymer attraction compared to the free LCST polymers. These simulation results provide guidance on the design of conjugated bio-mimetic thermoresponsive materials, and shape the fundamental understanding of the impact of polymer crowding on phase behavior in thermoresponsive LCST polymer systems.

Effect of oligonucleic acid (ONA) backbone features on assembly of ONA-star polymer conjugates: a coarse-grained molecular simulation study.

PubMed

Condon, Joshua E; Jayaraman, Arthi

2017-10-04

Understanding the impact of incorporating new physical and chemical features in oligomeric DNA mimics, termed generally as "oligonucleic acids" (ONAs), on their structure and thermodynamics will be beneficial in designing novel materials for a variety of applications. In this work, we conduct coarse-grained molecular simulations of ONA-star polymer conjugates with varying ONA backbone flexibility, ONA backbone charge, and number of arms in the star polymer at a constant ONA strand volume fraction to elucidate the effect of these design parameters on the thermodynamics and assembly of multi-arm ONA-star polymer conjugates. We quantify the thermo-reversible behavior of the ONA-star polymer conjugates by quantifying the hybridization of the ONA strands in the system as a function of temperature (i.e. melting curve). Additionally, we characterize the assembly of the ONA-star polymer conjugates by tracking cluster formation and percolation as a function of temperature, as well as cluster size distribution at temperatures near the assembly transition region. The key results are as follows. The melting temperature (T m ) of the ONA strands decreases upon going from a neutral to a charged ONA backbone and upon increasing flexibility of the ONA backbone. Similar behavior is seen for the assembly transition temperature (T a ) with varying ONA backbone charge and flexibility. While the number of arms in the ONA-star polymer conjugate has a negligible effect on the ONA T m in these systems, as the number of ONA-star polymer arms increase, the assembly temperature T a increases and local ordering in the assembled state improves. By understanding how factors like ONA backbone charge, backbone flexibility, and ONA-star polymer conjugate architecture impact the behavior of ONA-star polymer conjugate systems, we can better inform how the selection of ONA chemistry will influence resulting ONA-star polymer assembly.

Organic materials and devices for detecting ionizing radiation

DOEpatents

Doty, F Patrick [Livermore, CA; Chinn, Douglas A [Livermore, CA

2007-03-06

A .pi.-conjugated organic material for detecting ionizing radiation, and particularly for detecting low energy fission neutrons. The .pi.-conjugated materials comprise a class of organic materials whose members are intrinsic semiconducting materials. Included in this class are .pi.-conjugated polymers, polyaromatic hydrocarbon molecules, and quinolates. Because of their high resistivities (.gtoreq.10.sup.9 ohmcm), these .pi.-conjugated organic materials exhibit very low leakage currents. A device for detecting and measuring ionizing radiation can be made by applying an electric field to a layer of the .pi.-conjugated polymer material to measure electron/hole pair formation. A layer of the .pi.-conjugated polymer material can be made by conventional polymer fabrication methods and can be cast into sheets capable of covering large areas. These sheets of polymer radiation detector material can be deposited between flexible electrodes and rolled up to form a radiation detector occupying a small volume but having a large surface area. The semiconducting polymer material can be easily fabricated in layers about 10 .mu.m to 100 .mu.m thick. These thin polymer layers and their associated electrodes can be stacked to form unique multi-layer detector arrangements that occupy small volume.

Processing Conjugated-Diene-Containing Polymers

NASA Technical Reports Server (NTRS)

Bell, Vernon L.; Havens, Stephen J.

1987-01-01

Diels-Alder reaction used to cross-linked thermoplastics. Process uses Diels-Alder reaction to cross-link and/or extend conjugated-diene-containing polymers by reacting them with bis-unsaturated dienophiles results in improved polymer properties. Quantities of diene groups required for cross-linking varies from very low to very high concentrations. Process also used to extend, or build up molecular weights of, low-molecular-weight linear polymers with terminal conjugated dienic groups.

Highly Efficient Flexible Hybrid Photovoltaic Cells Based on Low-Band-Gap Conjugated Polymers Sensitized by Nanoparticle-Grafted Carbon

DTIC Science & Technology

2010-09-01

modeling, synthesis , and characterization of several series functional and processable electro-active conjugated polymers with evolving frontier...tasks as a basic obligation of this award: Task #1. Low Band Gap Polymers The awardee (Professor Sun’s group at NSU) shall design, synthesis , and...design, modeling, synthesis , and characterizations of several series functional and processable electro-active conjugated polymers with evolving

Solution Adsorption Formation of a π-Conjugated Polymer/Graphene Composite for High-Performance Field-Effect Transistors.

PubMed

Liu, Yun; Hao, Wei; Yao, Huiying; Li, Shuzhou; Wu, Yuchen; Zhu, Jia; Jiang, Lei

2018-01-01

Semiconducting polymers with π-conjugated electronic structures have potential application in the large-scale printable fabrication of high-performance electronic and optoelectronic devices. However, owing to their poor environmental stability and high-cost synthesis, polymer semiconductors possess limited device implementation. Here, an approach for constructing a π-conjugated polymer/graphene composite material to circumvent these limitations is provided, and then this material is patterned into 1D arrays. Driven by the π-π interaction, several-layer polymers can be adsorbed onto the graphene planes. The low consumption of the high-cost semiconductor polymers and the mass production of graphene contribute to the low-cost fabrication of the π-conjugated polymer/graphene composite materials. Based on the π-conjugated system, a reduced π-π stacking distance between graphene and the polymer can be achieved, yielding enhanced charge-transport properties. Owing to the incorporation of graphene, the composite material shows improved thermal stability. More generally, it is believed that the construction of the π-conjugated composite shows clear possibility of integrating organic molecules and 2D materials into microstructure arrays for property-by-design fabrication of functional devices with large area, low cost, and high efficiency. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method for synthesizing peptides with saccharide linked enzyme polymer conjugates

DOEpatents

Callstrom, Matthew R.; Bednarski, Mark D.; Gruber, Patrick R.

1997-01-01

A method is disclosed for synthesizing peptides using water soluble enzyme polymer conjugates. The method comprises catalyzing the peptide synthesis with enzyme which has been covalently bonded to a polymer through at least three linkers which linkers have three or more hydroxyl groups. The enzyme is conjugated at lysines or arginines.

Method for synthesizing peptides with saccharide linked enzyme polymer conjugates

DOEpatents

Callstrom, M.R.; Bednarski, M.D.; Gruber, P.R.

1997-06-17

A method is disclosed for synthesizing peptides using water soluble enzyme polymer conjugates. The method comprises catalyzing the peptide synthesis with enzyme which has been covalently bonded to a polymer through at least three linkers which linkers have three or more hydroxyl groups. The enzyme is conjugated at lysines or arginines. 19 figs.

Nanostructured Conjugated Polymers for Energy-Related Applications beyond Solar Cells.

PubMed

Xie, Jian; Zhao, Cui-E; Lin, Zong-Qiong; Gu, Pei-Yang; Zhang, Qichun

2016-05-20

To meet the ever-increasing requirements for the next generation of sustainable and versatile energy-related devices, conjugated polymers, which have potential advantages over small molecules and inorganic materials, are among the most promising types of green candidates. The properties of conjugated polymers can be tuned through modification of the structure and incorporation of different functional moieties. In addition, superior performances can be achieved as a result of the advantages of nanostructures, such as their large surface areas and the shortened pathways for charge transfer. Therefore, nanostructured conjugated polymers with different properties can be obtained to be applied in different energy-related organic devices. This review focuses on the application and performance of the recently reported nanostructured conjugated polymers for high-performance devices, including rechargeable lithium batteries, microbial fuel cells (MFCs), thermoelectric generators, and photocatalytic systems. The design strategies, reaction mechanisms, advantages, and limitations of nanostructured conjugated polymers are further discussed in each section. Finally, possible routes to improve the performances of the current systems are also included in the conclusion. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of pi-Conjugated Polymers for Transistor and Photovoltaic Applications

NASA Astrophysics Data System (ADS)

Paulsen, Bryan D.

pi-Conjugated polymers represent a unique class of optoelectronic materials. Being polymers, they are solution processable and inherently "soft" materials. This makes them attractive candidates for the production of roll-to-roll printed electronic devices on flexible substrates. The optical and electronic properties of pi-conjugated polymers are synthetically tunable allowing material sets to be tailored to specific applications. Two of the most heavily researched applications are the thin film transistor, the building block of electronic circuits, and the bulk heterojunction solar cell, which holds great potential as a renewable energy source. Key to developing commercially feasible pi-conjugated polymer devices is a thorough understanding of the electronic structure and charge transport behavior of these materials in relationship with polymer structure. Here this structure property relationship has been investigated through electrical and electrochemical means in concert with a variety of other characterization techniques and device test beds. The tunability of polymer optical band gap and frontier molecular orbital energy level was investigated in systems of vinyl incorporating statistical copolymers. Energy levels and band gaps are crucial parameters in developing efficient photovoltaic devices, with control of these parameters being highly desirable. Additionally, charge transport and density of electronic states were investigated in pi-conjugated polymers at extremely high electrochemically induced charge density. Finally, the effects of molecular weight on pi-conjugated polymer optical properties, energy levels, charge transport, morphology, and photovoltaic device performance was examined.

Conjugated amplifying polymers for optical sensing applications.

PubMed

Rochat, Sébastien; Swager, Timothy M

2013-06-12

Thanks to their unique optical and electrochemical properties, conjugated polymers have attracted considerable attention over the last two decades and resulted in numerous technological innovations. In particular, their implementation in sensing schemes and devices was widely investigated and produced a multitude of sensory systems and transduction mechanisms. Conjugated polymers possess numerous attractive features that make them particularly suitable for a broad variety of sensing tasks. They display sensory signal amplification (compared to their small-molecule counterparts) and their structures can easily be tailored to adjust solubility, absorption/emission wavelengths, energy offsets for excited state electron transfer, and/or for use in solution or in the solid state. This versatility has made conjugated polymers a fluorescence sensory platform of choice in the recent years. In this review, we highlight a variety of conjugated polymer-based sensory mechanisms together with selected examples from the recent literature.

9,10-Azaboraphenanthrene-containing small molecules and conjugated polymers: synthesis and their application in chemodosimeters for the ratiometric detection of fluoride ions.

PubMed

Zhang, Weidong; Li, Guoping; Xu, Letian; Zhuo, Yue; Wan, Wenming; Yan, Ni; He, Gang

2018-05-21

The introduction of main group elements into conjugated scaffolds is emerging as a key route to novel optoelectronic materials. Herein, an efficient and versatile way to synthesize polymerizable 9,10-azaboraphenanthrene ( BNP )-containing monomers by aromaticity-driven ring expansion reactions between highly antiaromatic borafluorene and azides is reported, and the corresponding conjugated small molecules and polymers are developed as well. The BNP -containing small molecules and conjugated polymers showed good air/moisture stability and notable fluorescence properties. Addition of fluoride ions to the BNP -based small molecules and polymers induced a rapid change in the emission color from blue to green/yellow, respectively, accompanied by strong intensity changes. The conjugated polymers showed better ratiometric sensing performance than small molecules due to the exciton migration along the conjugated chains. Further experiments showed that the sensing process is fully reversible. The films prepared by solution-deposition of BNP -based compounds in the presence of polycaprolactone also showed good ratiometric sensing for fluoride ions.

Theory of optical transitions in conjugated polymers. II. Real systems

NASA Astrophysics Data System (ADS)

Marcus, Max; Tozer, Oliver Robert; Barford, William

2014-10-01

The theory of optical transitions developed in Barford and Marcus ["Theory of optical transitions in conjugated polymers. I. Ideal systems," J. Chem. Phys. 141, 164101 (2014)] for linear, ordered polymer chains is extended in this paper to model conformationally disordered systems. Our key result is that in the Born-Oppenheimer regime the emission intensities are proportional to S(1)/⟨IPR⟩, where S(1) is the Huang-Rhys parameter for a monomer. ⟨IPR⟩ is the average inverse participation ratio for the emitting species, i.e., local exciton ground states (LEGSs). Since the spatial coherence of LEGSs determines the spatial extent of chromophores, the significance of this result is that it directly relates experimental observables to chromophore sizes (where ⟨IPR⟩ is half the mean chromophore size in monomer units). This result is independent of the chromophore shape, because of the Born-Oppenheimer factorization of the many body wavefunction. We verify this prediction by density matrix renormalization group (DMRG) calculations of the Frenkel-Holstein model in the adiabatic limit for both linear, disordered chains and for coiled, ordered chains. We also model optical spectra for poly(p-phenylene) and poly(p-phenylene-vinylene) oligomers and polymers. For oligomers, we solve the fully quantized Frenkel-Holstein model via the DMRG method. For polymers, we use the much simpler method of solving the one-particle Frenkel model and employ the Born-Oppenheimer expressions relating the effective Franck-Condon factor of a chromophore to its inverse participation ratio. We show that increased disorder decreases chromophore sizes and increases the inhomogeneous broadening, but has a non-monotonic effect on transition energies. We also show that as planarizing the polymer chain increases the exciton band width, it causes the chromophore sizes to increase, the transition energies to decrease, and the broadening to decrease. Finally, we show that the absorption spectra are more broadened than the emission spectra and that the broadening of the absorption spectra increases as the chains become more coiled. This is primarily because absorption occurs to both LEGSs and quasi-extended exciton states (QEESs), and QEES acquire increased intensity as chromophores bend, while emission only occurs from LEGSs.

Stabilized polyacrylic saccharide protein conjugates

DOEpatents

Callstrom, Matthew R.; Bednarski, Mark D.; Gruber, Patrick R.

1996-01-01

This invention is directed to water soluble protein polymer conjugates which are stabile in hostile environments. The conjugate comprises a protein which is linked to an acrylic polymer at multiple points through saccharide linker groups.

Synthesis, characterization, mucoadhesion and biocompatibility of thiolated carboxymethyl dextran-cysteine conjugate.

PubMed

Shahnaz, G; Perera, G; Sakloetsakun, D; Rahmat, D; Bernkop-Schnürch, A

2010-05-21

This study was aimed at improving the mucoadhesive properties of carboxymethyl dextran by the covalent attachment of cysteine. Mediated by a carbodiimide, l-cysteine was covalently attached to the polymer. The resulting CMD-cysteine conjugate (CMD-(273) conjugate) displayed 273+/-20 micromol thiol groups per gram of polymer (mean+/-S.D.; n=3). Within 2h the viscosity of an aqueous mucus/CMD-(273) conjugate mixture pH 7.4 increased at 37 degrees C by more than 85% compared to a mucus/carboxymethyl dextran mixture indicating enlarged interactions between the mucus and the thiolated polymer. Due to the immobilization of cysteine, the swelling velocity of the polymer was significantly accelerated (p<0.05). In aqueous solutions the CMD-(273) conjugate was capable of forming inter- and/or intramolecular disulfide bonds. Because of this crosslinking process within the polymeric network, the cohesive properties of the conjugate were also improved. Tablets comprising the unmodified polymer disintegrated within 15 min, whereas tablets of the CMD-(273) conjugate remained stable for 160 min (means+/-S.D.; n=3). Results from LDH and MTT assays on Caco-2 cells revealed 4.96+/-0.98% cytotoxicity and 94.1+/-0.9% cell viability for the CMD-(273) conjugate, respectively. Controlled release of model compound from CMD-(273) conjugate tablets was observed over 6h. These findings suggest that CMD-(273) conjugate is a promising novel polymer for drug delivery systems providing improved mucoadhesive and cohesive properties, greater stability and biocompatibility. Copyright 2010 Elsevier B.V. All rights reserved.

Particle-in-a-box model of exciton absorption and electroabsorption in conjugated polymers

NASA Astrophysics Data System (ADS)

Pedersen, Thomas G.

2000-12-01

The recently proposed particle-in-a-box model of one-dimensional excitons in conjugated polymers is applied in calculations of optical absorption and electroabsorption spectra. It is demonstrated that for polymers of long conjugation length a superposition of single exciton resonances produces a line shape characterized by a square-root singularity in agreement with experimental spectra near the absorption edge. The effects of finite conjugation length on both absorption and electroabsorption spectra are analyzed.

Dehydration Polymerization for Poly(hetero)arene Conjugated Polymers.

PubMed

Mirabal, Rafael A; Vanderzwet, Luke; Abuadas, Sara; Emmett, Michael R; Schipper, Derek

2018-02-18

The lack of scalable and sustainable methods to prepare conjugated polymers belies their importance in many enabling technologies. Accessing high-performance poly(hetero)arene conjugated polymers by dehydration has remained an unsolved problem in synthetic chemistry and has historically required transitional-metal coupling reactions. Herein, we report a dehydration method that allows access to conjugated heterocyclic materials. By using the technique, we have prepared a series of small molecules and polymers. The reaction avoids using transition metals, proceeds at room temperature, the only required reactant is a simple base and water is the sole by-product. The dehydration reaction is technically simple and provides a sustainable and straightforward method to prepare conjugated heteroarene motifs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Integrated circuits based on conjugated polymer monolayer

DOE PAGES

Li, Mengmeng; Mangalore, Deepthi Kamath; Zhao, Jingbo; ...

2018-01-31

It is still a great challenge to fabricate conjugated polymer monolayer field-effect transistors (PoM-FETs) due to intricate crystallization and film formation of conjugated polymers. Here we demonstrate PoM-FETs based on a single monolayer of a conjugated polymer. The resulting PoM-FETs are highly reproducible and exhibit charge carrier mobilities reaching 3 cm 2 V -1 s -1. The high performance is attributed to the strong interactions of the polymer chains present already in solution leading to pronounced edge-on packing and well-defined microstructure in the monolayer. The high reproducibility enables the integration of discrete unipolar PoM-FETs into inverters and ring oscillators. Realmore » logic functionality has been demonstrated by constructing a 15-bit code generator in which hundreds of self-assembled PoM-FETs are addressed simultaneously. Lastly, our results provide the state-of-the-art example of integrated circuits based on a conjugated polymer monolayer, opening prospective pathways for bottom-up organic electronics.« less

Integrated circuits based on conjugated polymer monolayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Mengmeng; Mangalore, Deepthi Kamath; Zhao, Jingbo

It is still a great challenge to fabricate conjugated polymer monolayer field-effect transistors (PoM-FETs) due to intricate crystallization and film formation of conjugated polymers. Here we demonstrate PoM-FETs based on a single monolayer of a conjugated polymer. The resulting PoM-FETs are highly reproducible and exhibit charge carrier mobilities reaching 3 cm 2 V -1 s -1. The high performance is attributed to the strong interactions of the polymer chains present already in solution leading to pronounced edge-on packing and well-defined microstructure in the monolayer. The high reproducibility enables the integration of discrete unipolar PoM-FETs into inverters and ring oscillators. Realmore » logic functionality has been demonstrated by constructing a 15-bit code generator in which hundreds of self-assembled PoM-FETs are addressed simultaneously. Lastly, our results provide the state-of-the-art example of integrated circuits based on a conjugated polymer monolayer, opening prospective pathways for bottom-up organic electronics.« less

Integrated circuits based on conjugated polymer monolayer.

PubMed

Li, Mengmeng; Mangalore, Deepthi Kamath; Zhao, Jingbo; Carpenter, Joshua H; Yan, Hongping; Ade, Harald; Yan, He; Müllen, Klaus; Blom, Paul W M; Pisula, Wojciech; de Leeuw, Dago M; Asadi, Kamal

2018-01-31

It is still a great challenge to fabricate conjugated polymer monolayer field-effect transistors (PoM-FETs) due to intricate crystallization and film formation of conjugated polymers. Here we demonstrate PoM-FETs based on a single monolayer of a conjugated polymer. The resulting PoM-FETs are highly reproducible and exhibit charge carrier mobilities reaching 3 cm 2  V -1  s -1 . The high performance is attributed to the strong interactions of the polymer chains present already in solution leading to pronounced edge-on packing and well-defined microstructure in the monolayer. The high reproducibility enables the integration of discrete unipolar PoM-FETs into inverters and ring oscillators. Real logic functionality has been demonstrated by constructing a 15-bit code generator in which hundreds of self-assembled PoM-FETs are addressed simultaneously. Our results provide the state-of-the-art example of integrated circuits based on a conjugated polymer monolayer, opening prospective pathways for bottom-up organic electronics.

Study of biodegradable polymers for ``green'' devices

NASA Astrophysics Data System (ADS)

Perez, Carlos; Jiang, Xiaomei; Jiang Group Team

2015-03-01

Π - conjugated polymers such as polythiophenes are conventional picks for cost-effective organic solar cells. However, these organic semiconductors are not environment-friendly since the polymer back bones require temperature higher than 3000C to be decomposed, thus will cause potential environment problems upon disposal. In this work, the optical and electronic properties of biodegradable polymers, conjugated poly(disulfidediamine), were examined via continuous wave laser spectroscopy, FTIR spectroscopy and conductivity measurement. We found that the attachment of a side chain to aromatic ring increases both photo and thermal stability, as well as higher conductivity. Thermal annealing improved the film morphological, photophysical and electronic properties. Photo-Induced Absorption (PIA) reveals different features comparing with conventional pi-conjugated polymers. No observation of long-lived photoexcitations such as polarons or triplets which are common with pi-conjugated polymers. Instead, we found the formation of low energy species upon thermal annealing in these biodegradable polymers.

Conjugated polymer/nanocrystal nanocomposites for renewable energy applications in photovoltaics and photocatalysis.

PubMed

Su, Yu-Wei; Lin, Wei-Hao; Hsu, Yung-Jung; Wei, Kung-Hwa

2014-11-01

Conjugated polymer/nanocrystal composites have attracted much attention for use in renewable energy applications because of their versatile and synergistic optical and electronic properties. Upon absorbing photons, charge separation occurs in the nanocrystals, generating electrons and holes for photocurrent flow or reduction/oxidation (redox) reactions under proper conditions. Incorporating these nanocrystals into conjugated polymers can complement the visible light absorption range of the polymers for photovoltaics applications or allow the polymers to sensitize or immobilize the nanocrystals for photocatalysis. Here, the current developments of conjugated polymer/nanocrystal nanocomposites for bulk heterojunction-type photovoltaics incorporating Cd- and Pb-based nanocrystals or quantum dots are reviewed. The effects of manipulating the organic ligands and the concentration of the nanocrystal precursor, critical factors that affect the shape and aggregation of the nanocrystals, are also discussed. In the conclusion, the mechanisms through which conjugated polymers can sensitize semiconductor nanocrystals (TiO2 , ZnO) to ensure efficient charge separation, as well as how they can support immobilized nanocrystals for use in photocatalysis, are addressed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular Approach to Conjugated Polymers with Biomimetic Properties.

PubMed

Baek, Paul; Voorhaar, Lenny; Barker, David; Travas-Sejdic, Jadranka

2018-06-13

The field of bioelectronics involves the fascinating interplay between biology and human-made electronics. Applications such as tissue engineering, biosensing, drug delivery, and wearable electronics require biomimetic materials that can translate the physiological and chemical processes of biological systems, such as organs, tissues. and cells, into electrical signals and vice versa. However, the difference in the physical nature of soft biological elements and rigid electronic materials calls for new conductive or electroactive materials with added biomimetic properties that can bridge the gap. Soft electronics that utilize organic materials, such as conjugated polymers, can bring many important features to bioelectronics. Among the many advantages of conjugated polymers, the ability to modulate the biocompatibility, solubility, functionality, and mechanical properties through side chain engineering can alleviate the issues of mechanical mismatch and provide better interface between the electronics and biological elements. Additionally, conjugated polymers, being both ionically and electrically conductive through reversible doping processes provide means for direct sensing and stimulation of biological processes in cells, tissues, and organs. In this Account, we focus on our recent progress in molecular engineering of conjugated polymers with tunable biomimetic properties, such as biocompatibility, responsiveness, stretchability, self-healing, and adhesion. Our approach is general and versatile, which is based on functionalization of conjugated polymers with long side chains, commonly polymeric or biomolecules. Applications for such materials are wide-ranging, where we have demonstrated conductive, stimuli-responsive antifouling, and cell adhesive biointerfaces that can respond to external stimuli such as temperature, salt concentration, and redox reactions, the processes that in turn modify and reversibly switch the surface properties. Furthermore, utilizing the advantageous chemical, physical, mechanical and functional properties of the grafts, we progressed into grafting of the long side chains onto conjugated polymers in solution, with the vision of synthesizing solution-processable conjugated graft copolymers with biomimetic functionalities. Examples of the developed materials to date include rubbery and adhesive photoluminescent plastics, biomolecule-functionalized electrospun biosensors, thermally and dually responsive photoluminescent conjugated polymers, and tunable self-healing, adhesive, and stretchable strain sensors, advanced functional biocidal polymers, and filtration membranes. As outlined in these examples, the applications of these biomimetic, conjugated polymers are still in the development stage toward truly printable, organic bioelectronic devices. However, in this Account, we advocate that molecular engineering of conjugated polymers is an attractive approach to a versatile class of organic electronics with both ionic and electrical conductivity as well as mechanical properties required for next-generation bioelectronics.

Simple Protein Modification Using Zwitterionic Polymer to Mitigate the Bioactivity Loss of Conjugated Insulin.

PubMed

Xie, Jinbing; Lu, Yang; Wang, Wei; Zhu, Hui; Wang, Zhigang; Cao, Zhiqiang

2017-06-01

Polymer-protein conjugation has been extensively explored toward a better protein drug with improved pharmacokinetics. However, a major problem with polymer-protein conjugation is that the polymers drastically reduce the bioactivity of the modified protein. There is no perfect solution to prevent the bioactivity loss, no matter the polymer is conjugated in a non-site specific way, or a more complex site-specific procedure. Here the authors report for the first time that when zwitterionic carboxybetaine polymer (PCB) is conjugated to insulin through simple conventional coupling chemistry. The resulting PCB-insulin does not show a significant reduction of in vitro bioactivity. The obtained PCB-insulin shows two significant advantages as a novel pharmaceutical agent. First, its therapeutic performance is remarkable. For PCB-insulin, there is a 24% increase of in vivo pharmacological activity of lowering blood glucose compared with native insulin. Such uncommonly seen increase has rarely been reported and is expected to be due to both the improved pharmacokinetics and retained bioactivity of PCB-insulin. Second, the production is simple from manufacturing standpoints. Conjugation procedure involves only one-step coupling reaction without complex site-specific linkage technique. The synthesized PCB-insulin conjugates do not require chromatographic separation to purify and obtain particular isoforms. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stabilized polyacrylic saccharide protein conjugates

DOEpatents

Callstrom, M.R.; Bednarski, M.D.; Gruber, P.R.

1996-02-20

This invention is directed to water soluble protein polymer conjugates which are stable in hostile environments. The conjugate comprises a protein which is linked to an acrylic polymer at multiple points through saccharide linker groups. 16 figs.

Hierarchical assembly of branched supramolecular polymers from (cyclic Peptide)-polymer conjugates.

PubMed

Koh, Ming Liang; Jolliffe, Katrina A; Perrier, Sébastien

2014-11-10

We report the synthesis and assembly of (N-methylated cyclic peptide)-polymer conjugates for which the cyclic peptide is attached to either the α- or both α- and ω- end groups of a polymer. A combination of chromatographic, spectroscopic, and scattering techniques reveals that the assembly of the conjugates follows a two-level hierarchy, initially driven by H-bond formation between two N-methylated cyclic peptides, followed by unspecific, noncovalent aggregation of this peptide into small domains that behave as branching points and lead to the formation of branched supramolecular polymers.

Double Modification of Polymer End Groups through Thiolactone Chemistry.

PubMed

Driessen, Frank; Martens, Steven; Meyer, Bernhard De; Du Prez, Filip E; Espeel, Pieter

2016-06-01

A straightforward synthetic procedure for the double modification and polymer-polymer conjugation of telechelic polymers is performed through amine-thiol-ene conjugation. Thiolactone end-functionalized polymers are prepared via two different methods, through controlled radical polymerization of a thiolactone-containing initiator, or by modification of available end-functionalized polymers. Next, these different linear polymers are treated with a variety of amine/acrylate-combinations in a one-pot procedure, creating a library of tailored end-functionalized polymers. End group conversions are monitored via SEC, NMR, and MALDI-TOF analysis, confirming the quantitative modification after each step. Finally, this strategy is applied for the synthesis of block copolymers via polymer-polymer conjugation and the successful outcome is analyzed via LCxSEC measurements. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stabilization of Resveratrol in Blood Circulation by Conjugation to mPEG and mPEG-PLA Polymers: Investigation of Conjugate Linker and Polymer Composition on Stability, Metabolism, Antioxidant Activity and Pharmacokinetic Profile

PubMed Central

Siddalingappa, Basavaraj; Benson, Heather A. E.; Brown, David H.; Batty, Kevin T.; Chen, Yan

2015-01-01

Resveratrol is naturally occurring phytochemical with diverse biological activities such as chemoprevention, anti-inflammatory, anti-cancer, anti-oxidant. But undergoes rapid metabolism in the body (half life 0.13h). Hence Polymer conjugation utilizing different chemical linkers and polymer compositions was investigated for enhanced pharmacokinetic profile of resveratrol. Ester conjugates such as α-methoxy-ω-carboxylic acid poly(ethylene glycol) succinylamide resveratrol (MeO-PEGN-Succ-RSV) (2 and 20 kDa); MeO-PEG succinyl ester resveratrol (MeO-PEGO-Succ-RSV) (2 kDa); α-methoxy poly(ethylene glycol)-co-polylactide succinyl ester resveratrol (MeO-PEG-PLAO-Succ-RSV) (2 and 6.6kDa) were prepared by carbodiimide coupling reactions. Resveratrol-PEG ethers (2 and 5 kDa) were synthesized by alkali-mediated etherification. All polymer conjugates were fully characterized in vitro and the pharmacokinetic profile of selected conjugates was characterized in rats. Buffer and plasma stability of conjugates was dependent on polymer hydrophobicity, aggregation behavior and PEG corona, with MeO-PEG-PLAO-Succ-RSV (2 kDa) showing a 3h half-life in rat plasma in vitro. Polymer conjugates irrespective of linker chemistry protected resveratrol against metabolism in vitro. MeO-PEG-PLAO-Succ-RSV (2 kDa), Resveratrol-PEG ether (2 and 5 kDa) displayed improved pharmacokinetic profiles with significantly higher plasma area under curve (AUC), slower clearance and smaller volume of distribution, compared to resveratrol. PMID:25799413

Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers

DTIC Science & Technology

2016-06-15

with end-functionalized polymers . First, an end-functionalized polymer with conjugated end-molecule, pyrene, is successfully employed to boron... polymers . First, an end-functionalized polymer with conjugated end-molecule, pyrenes, is successfully employed to boron nitride nanosheets (BNNS), and...AFRL-AFOSR-JP-TR-2016-0071 Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers Cheolmin Park YONSEI UNIVERSITY

From 1D Polymers to 2D Polymers: Preparation of Free-Standing Single-Monomer-Thick Two-Dimensional Conjugated Polymers in Water.

PubMed

Zhang, Na; Wang, Taisheng; Wu, Xing; Jiang, Chen; Zhang, Taiming; Jin, Bangkun; Ji, Hengxing; Bai, Wei; Bai, Ruke

2017-07-25

Recently, investigation on two-dimensional (2D) organic polymers has made great progress, and conjugated 2D polymers already play a dynamic role in both academic and practical applications. However, a convenient, noninterfacial approach to obtain single-layer 2D polymers in solution, especially in aqueous media, remains challenging. Herein, we present a facile, highly efficient, and versatile "1D to 2D" strategy for preparation of free-standing single-monomer-thick conjugated 2D polymers in water without any aid. The 2D structure was achieved by taking advantage of the side-by-side self-assembly of a rigid amphiphilic 1D polymer and following topochemical photopolymerization in water. The spontaneous formation of single-layer polymer sheets was driven by synergetic association of the hydrophobic interactions, π-π stacking interactions, and electrostatic repulsion. Both the supramolecular sheets and the covalent sheets were confirmed by spectroscopic analyses and electron microscope techniques. Moreover, in comparison of the supramolecular 2D polymer, the covalent 2D polymer sheets exhibited not only higher mechanical strength but also higher conductivity, which can be ascribed to the conjugated network within the covalent 2D polymer sheets.

Photogeneration of Charge Carriers in Bilayer Assemblies of Conjugated Rigid-Rod Polymers

DTIC Science & Technology

1994-07-08

photoinduced electron transfer and exciplex formation at the bilayer interface. Thus photocarrier generation on photoexcitation of the conjugated rigid...rod polymers in the bilayer occurs by photoinduced electron transfer, forming intermolecular exciplexes which dissociate efficiently in electric field...photogeneration, conjugated rigid-rod polymers, is. MACI COD bilayer assemblies, electron transfer, exciplexes . 11. SEOJUTY CLASUICA 10. 51(11MIE CLASSIMIAVION

A Triphenylamine-Based Conjugated Polymer with Donor-π-Acceptor Architecture as Organic Sensitizer for Dye-Sensitized Solar Cells.

PubMed

Zhang, Wei; Fang, Zhen; Su, Mingjuan; Saeys, Mark; Liu, Bin

2009-09-17

A conjugated polymer containing an electron donating backbone (triphenylamine) and an electron accepting side chain (cyanoacetic acid) with conjugated thiophene units as the linkers has been synthesized. Dye-sensitized solar cells (DSSCs) are fabricated utilizing this material as the dye sensitizer, resulting a typical power conversion efficiency of 3.39% under AM 1.5 G illumination, which represents the highest efficiency for polymer dye-sensitized DSSCs reported so far. The results show the good promise of conjugated polymers as sensitizers for DSSC applications. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The pH-dependent and enzymatic release of cytarabine from hydrophilic polymer conjugates.

PubMed

Pola, R; Janoušková, O; Etrych, T

2016-10-20

Cytarabine is one of the most efficient drugs in the treatment of hematological malignancies. In this work, we describe the synthesis and characterization of two different polymer conjugates of cytarabine that were designed for the controlled release of cytarabine within the leukemia cells. Reactive copolymers of N-(2-hydroxypropyl)methacrylamide (HPMA) and 3-(3-methacrylamidopropa-noyl)thiazolidine-2-thione) or 3-(Nmethacryloylglycyl-phenylalanylleucylglycyl)thiazolidine-2-thione were used in the study as reactive polymer precursors for reaction with cytarabine. The enzymatic release of cytarabine from the conjugate containing a GFLG spacer utilizing cathepsin B was verified. In addition to enzymolysis, the pH-dependent hydrolysis of cytarabine from both copolymers was also confirmed. Approximately 40 % and 20 % of the drug was released by spontaneous hydrolysis at pH 7.4 within 72 h from the polymer conjugates with the GFLG and beta-Ala spacers, respectively. At pH 6.0, the spontaneous hydrolysis slowed down, and less than 10 % of the drug was liberated within 72 h. The results of the cytotoxicity evaluation of the polymer conjugates in vitro against various cell lines showed that the cytotoxicity of the polymer conjugates is approximately three times lower in comparison to free cytarabine.

Functional Hybrid Biomaterials based on Peptide-Polymer Conjugates for Nanomedicine

NASA Astrophysics Data System (ADS)

Shu, Jessica Yo

The focus of this dissertation is the design, synthesis and characterization of hybrid functional biomaterials based on peptide-polymer conjugates for nanomedicine. Generating synthetic materials with properties comparable to or superior than those found in nature has been a "holy grail" for the materials community. Man-made materials are still rather simplistic when compared to the chemical and structural complexity of a cell. Peptide-polymer conjugates have the potential to combine the advantages of the biological and synthetic worlds---that is they can combine the precise chemical structure and diverse functionality of biomolecules with the stability and processibility of synthetic polymers. As a new family of soft matter, they may lead to materials with novel properties that have yet to be realized with either of the components alone. In order for peptide-polymer conjugates to reach their full potential as useful materials, the structure and function of the peptide should be maintained upon polymer conjugation. The success in achieving desirable, functional assemblies relies on fundamentally understanding the interactions between each building block and delicately balancing and manipulating these interactions to achieve targeted assemblies without interfering with designed structures and functionalities. Such fundamental studies of peptide-polymer interactions were investigated as the nature of the polymer (hydrophilic vs. hydrophobic) and the site of its conjugation (end-conjugation vs. side-conjugation) were varied. The fundamental knowledge gained was then applied to the design of amphiphiles that self-assemble to form stable functional micelles. The micelles exhibited exceptional monodispersity and long-term stability, which is atypical of self-assembled systems. Thus such micelles based on amphiphilic peptide-polymer conjugates may meet many current demands in nanomedicine, in particular for drug delivery of hydrophobic anti-cancer therapeutics. Lastly, biological evaluations were performed to investigate the potential of micelles as drug delivery vehicles. In vitro cell studies demonstrated that the micelles can be used as a delivery vehicle to tailor the cellular uptake, time release, and intracellular trafficking of drugs. In vivo biodistribution and pharmacokinetic experiments showed long blood circulation. This work demonstrates that peptide-polymer conjugates can be used as building blocks to generate hierarchical functional nanostructures with a wide range of applications, only one of which is drug delivery.

Liquid scintillators with near infrared emission based on organoboron conjugated polymers.

PubMed

Tanaka, Kazuo; Yanagida, Takayuki; Yamane, Honami; Hirose, Amane; Yoshii, Ryousuke; Chujo, Yoshiki

2015-11-15

The organic liquid scintillators based on the emissive polymers are reported. A series of conjugated polymers containing organoboron complexes which show the luminescence in the near infrared (NIR) region were synthesized. The polymers showed good solubility in common organic solvents. From the comparison of the luminescent properties of the synthesized polymers between optical and radiation excitation, similar emission bands were detected. In addition, less significant degradation was observed. These data propose that the organoboron conjugated polymers are attractive platforms to work as an organic liquid scintillator with the emission in the NIR region. Copyright © 2015 Elsevier Ltd. All rights reserved.

Controlled Supramolecular Self-Assembly of Super-charged β-Lactoglobulin A-PEG Conjugates into Nanocapsules.

PubMed

Khan, Amit Kumar; Gudlur, Sushanth; de Hoog, Hans-Peter M; Siti, Winna; Liedberg, Bo; Nallani, Madhavan

2017-09-18

The synthesis and characterization of a new protein-polymer conjugate composed of β lactoglobulin A (βLG A) and poly(ethylene glycol) PEG is described. βLG A was selectively modified to self-assemble by super-charging via amination or succinylation followed by conjugation with PEG. An equimolar mixture of the oppositely charged protein-polymer conjugates self-assemble into spherical capsules of 80-100 nm in diameter. The self-assembly proceeds by taking simultaneous advantage of the amphiphilicity and polyelectrolyte nature of the protein-polymer conjugate. These protein-polymer capsules or proteinosomes are reminiscent of protein capsids, and are capable of encapsulating solutes in their interior. We envisage this approach to be applicable to other globular proteins. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-assembly of conjugated oligomers and polymers at the interface: structure and properties.

PubMed

Xu, Lirong; Yang, Liu; Lei, Shengbin

2012-08-07

In this review, we give a brief account on the recent scanning tunneling microscopy investigation of interfacial structures and properties of π-conjugated semiconducting oligomers and polymers, either at the solid-air (including solid-vacuum) or at the solid-liquid interface. The structural aspects of the self-assembly of both oligomers and polymers are highlighted. Conjugated oligomers can form well ordered supramolecular assemblies either at the air-solid or liquid-solid interface, thanks to the relatively high mobility and structural uniformity in comparison with polymers. The backbone structure, substitution of side chains and functional groups can affect the assembling behavior significantly, which offers the opportunity to tune the supramolecular structure of these conjugated oligomers at the interface. For conjugated polymers, the large molecular weight limits the mobility on the surface and the distribution in size also prevents the formation of long range ordered supramolecular assembly. The submolecular resolution obtained on the assembling monolayers enables a detailed investigation of the chain folding at the interface, both the structural details and the effect on electronic properties. Besides the ability in studying the assembling structures at the interfaces, STM also provides a reasonable way to evaluate the distribution of the molecular weight of conjugated polymers by statistic of the contour length of the adsorbed polymer chains. Both conjugated oligomers and polymers can form composite assemblies with other materials. The ordered assembly of oligomers can act as a template to controllably disperse other molecules such as coronene or fullerene. These investigations open a new avenue to fine tune the assembling structure at the interface and in turn the properties of the composite materials. To summarize scanning tunneling microscopy has demonstrated its surprising ability in the investigation of the assembling structures and properties of conjugated oligomers and polymers. The information obtained could benefit the understanding of the elements affecting the film morphology and helps the optimization of device performance.

Toward High Performance Photovoltaic Cells based on Conjugated Polymers

DTIC Science & Technology

2016-12-26

AFRL-AFOSR-JP-TR-2016-0103 Toward High Performance Photovoltaic Cells based on Conjugated Polymers Kung-Hwa Wei National Chiao Tung University Final...Conjugated Polymers 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-15-1-4113 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Kung-Hwa Wei 5d.  PROJECT...gap polymer with good packing order as the active layer for a single-junction photovoltaic device. The light absorptions for the small molecule and the

Structural dependence of MEH-PPV chromism in solution.

PubMed

de Magalhães, Carlos E T; Savedra, Ranylson M L; Dias, Karina S; Ramos, Rodrigo; Siqueira, Melissa F

2017-03-01

The chromism observed in the MEH-PPV polymer in tetrahydrofuran (THF) solution is discussed as a function of the structural morphology of the backbone chains. To evaluate this phenomenon, we carried out simulations employing a hybrid methodology using molecular dynamics and quantum mechanical approaches. Our results support the hypothesis that the morphological order-disorder transition is related to the change from red to blue phase observed experimentally. The morphological disorder is associated with total or partial twisted arrangements in the polymer backbone, which induces an electronic conjugation length more confined to shorter segments. In addition, the main band of the MEH-PPV UV-Vis spectrum at the lower wavelength is related to the blue phase, in contrast to the red phase found for the more planar backbone chains.

Sequence-Controlled Polymerization on Facially Amphiphilic Templates at Interfaces

DTIC Science & Technology

2016-06-14

controlled chain growth polymerization. We will synthesize a ?- conjugated “parent” polymer by iterative exponential growth (IEG), attach cyclic olefin...template that is programmed to direct sequence- controlled chain growth polymerization. We will synthesize a ?- conjugated “parent” polymer by iterative...polymerization. We will synthesize a π- conjugated “parent” polymer by organometallic iterative exponential growth (IEG),2 attach cyclic olefin “daughter

Photocatalysts Based on Cobalt-Chelating Conjugated Polymers for Hydrogen Evolution from Water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Lianwei; Hadt, Ryan G.; Yao, Shiyu

Developing photocatalytic systems for water splitting to generate oxygen and hydrogen is one of the biggest chemical challenges in solar energy utilization. In this work, we report the first example of heterogeneous photocatalysts for hydrogen evolution based on in-chain cobalt-chelating conjugated polymers. Four conjugated polymers chelated with earth abundant cobalt ions were synthesized and found to evolve hydrogen photocatalytically from water. These polymers are designed to combine functions of the conjugated backbone as light-harvesting antenna and electron transfer conduit with the in-chain bipyridyl chelated transition metal centers as catalytic active sites. In addition, these polymers are soluble in organic solvents,more » enabling effective interactions with the substrates as well as detailed characterization. We also found a polymer-dependent optimal cobalt chelating concentration at which the highest photocatalytic hydrogen production (PHP) activity can be achieved.« less

A Helical Flow, Circular Microreactor For Separating and Enriching “Smart” Polymer-Antibody Capture Reagents

PubMed Central

Hoffman, John M.; Ebara, Mitsuhiro; Lai, James J.; Hoffman, Allan S.; Folch, Albert

2011-01-01

We report a mechanistic study of how flow and recirculation in a microreactor can be used to optimize the capture and release of stimuli-responsive polymer-protein reagents on stimuli-responsive polymer-grafted channel surfaces. Poly(N-isopropylacrylamide) (PNIPAAm) was grafted to poly(dimethyl)siloxane (PDMS) channel walls, creating switchable surfaces where PNIPAAm-protein conjugates would adhere at temperatures above the lower critical solution temperature (LCST) and released below the LCST. A PNIPAAm-streptavidin conjugate that can capture biotinylated antibody-antigen targets was first characterized. The conjugate’s immobilization and release were limited by mass transport to and from the functionalized PNIPAAm surface. Transport and adsorption efficiencies were dependent on the aggregate size of the PNIPAAm-streptavidin conjugate above the LCST and also was dependent on whether the conjugates were heated in the presence of the stimuli-responsive surface or pre-aggregated and then flowed across the surface. As conjugate size increased, through the addition of non-conjugated PNIPAAm, recirculation and mixing were shown to markedly improve conjugate immobilization compared to diffusion alone. Under optimized conditions of flow and reagent concentrations, approximately 60% of a streptavidin conjugate bolus could be captured at the surface and subsequently successfully released. The kinetic release profile sharpness was also strongly improved with recirculation and helical mixing. Finally, the concentration of protein-polymer conjugates could be achieved by continuous conjugate flow into the heated recirculator, allowing nearly linear enrichment of the conjugate reagent from larger volumes. This capability was shown with anti-p24 HIV monoclonal antibody reagents that were enriched over 5-fold using this protocol. These studies provide insight into the mechanism of smart polymer-protein conjugate capture and release in grafted channels and show the potential of this purification and enrichment module for processing diagnostic samples. PMID:20882219

Rapid and Highly Sensitive Detection of Dopamine Using Conjugated Oxaborole-Based Polymer and Glycopolymer Systems.

PubMed

Jiang, Keren; Wang, Yinan; Thakur, Garima; Kotsuchibashi, Yohei; Naicker, Selvaraj; Narain, Ravin; Thundat, Thomas

2017-05-10

A conjugated polymer interface consisting of an oxaborole containing polymer and a glycopolymer was used for achieving very high selectivity in dopamine (DA) detection. The optimum binding affinity between the polymers promotes the selectivity to DA through a displacement mechanism while remaining unaffected by other structurally related analogs and saccharide derivatives. Real-time detection of DA with very high selectivity and sensitivity has been demonstrated by immobilizing the polymer conjugates on surface plasmon resonance (SPR) and microcantilever (MCL) sensor platforms. Using the conjugated polymer sensing layer, the SPR biosensor was capable of detecting DA in the concentration range of 1 × 10 -9 to 1 × 10 -4 mol L -1 , whereas the MCL sensor showed a limit of detection (LOD) of 5 × 10 -11 mol L -1 . We find that the sensing mechanism is based on DA-induced reversible swelling of the conjugated polymer layer and this allows regeneration and reuse of the sensor multiple times. Also, we conclude that SPR is a suitable sensor platform for DA in-line detection at clinical level considering the detection time and stability, whereas MCL can achieve a much lower LOD.

Chain-Length-Dependent Exciton Dynamics in Linear Oligothiophenes Probed Using Ensemble and Single-Molecule Spectroscopy.

PubMed

Kim, Tae-Woo; Kim, Woojae; Park, Kyu Hyung; Kim, Pyosang; Cho, Jae-Won; Shimizu, Hideyuki; Iyoda, Masahiko; Kim, Dongho

2016-02-04

Exciton dynamics in π-conjugated molecular systems is highly susceptible to conformational disorder. Using time-resolved and single-molecule spectroscopic techniques, the effect of chain length on the exciton dynamics in a series of linear oligothiophenes, for which the conformational disorder increased with increasing chain length, was investigated. As a result, extraordinary features of the exciton dynamics in longer-chain oligothiophene were revealed. Ultrafast fluorescence depolarization processes were observed due to exciton self-trapping in longer and bent chains. Increase in exciton delocalization during dynamic planarization processes was also observed in the linear oligothiophenes via time-resolved fluorescence spectra but was restricted in L-10T because of its considerable conformational disorder. Exciton delocalization was also unexpectedly observed in a bent chain using single-molecule fluorescence spectroscopy. Such delocalization modulates the fluorescence spectral shape by attenuating the 0-0 peak intensity. Collectively, these results provide significant insights into the exciton dynamics in conjugated polymers.

Entropic (de)stabilization of surface-bound peptides conjugated with polymers

NASA Astrophysics Data System (ADS)

Carmichael, Scott P.; Shell, M. Scott

2015-12-01

In many emerging biotechnologies, functional proteins must maintain their native structures on or near interfaces (e.g., tethered peptide arrays, protein coated nanoparticles, and amphiphilic peptide micelles). Because the presence of a surface is known to dramatically alter the thermostability of tethered proteins, strategies to stabilize surface-bound proteins are highly sought. Here, we show that polymer conjugation allows for significant control over the secondary structure and thermostability of a model surface-tethered peptide. We use molecular dynamics simulations to examine the folding behavior of a coarse-grained helical peptide that is conjugated to polymers of various lengths and at various conjugation sites. These polymer variations reveal surprisingly diverse behavior, with some stabilizing and some destabilizing the native helical fold. We show that ideal-chain polymer entropies explain these varied effects and can quantitatively predict shifts in folding temperature. We then develop a generic theoretical model, based on ideal-chain entropies, that predicts critical lengths for conjugated polymers to effect changes in the folding of a surface-bound protein. These results may inform new design strategies for the stabilization of surface-associated proteins important for a range technological applications.

Entropic (de)stabilization of surface-bound peptides conjugated with polymers.

PubMed

Carmichael, Scott P; Shell, M Scott

2015-12-28

In many emerging biotechnologies, functional proteins must maintain their native structures on or near interfaces (e.g., tethered peptide arrays, protein coated nanoparticles, and amphiphilic peptide micelles). Because the presence of a surface is known to dramatically alter the thermostability of tethered proteins, strategies to stabilize surface-bound proteins are highly sought. Here, we show that polymer conjugation allows for significant control over the secondary structure and thermostability of a model surface-tethered peptide. We use molecular dynamics simulations to examine the folding behavior of a coarse-grained helical peptide that is conjugated to polymers of various lengths and at various conjugation sites. These polymer variations reveal surprisingly diverse behavior, with some stabilizing and some destabilizing the native helical fold. We show that ideal-chain polymer entropies explain these varied effects and can quantitatively predict shifts in folding temperature. We then develop a generic theoretical model, based on ideal-chain entropies, that predicts critical lengths for conjugated polymers to effect changes in the folding of a surface-bound protein. These results may inform new design strategies for the stabilization of surface-associated proteins important for a range technological applications.

"Double-Cable" Conjugated Polymers with Linear Backbone toward High Quantum Efficiencies in Single-Component Polymer Solar Cells.

PubMed

Feng, Guitao; Li, Junyu; Colberts, Fallon J M; Li, Mengmeng; Zhang, Jianqi; Yang, Fan; Jin, Yingzhi; Zhang, Fengling; Janssen, René A J; Li, Cheng; Li, Weiwei

2017-12-27

A series of "double-cable" conjugated polymers were developed for application in efficient single-component polymer solar cells, in which high quantum efficiencies could be achieved due to the optimized nanophase separation between donor and acceptor parts. The new double-cable polymers contain electron-donating poly(benzodithiophene) (BDT) as linear conjugated backbone for hole transport and pendant electron-deficient perylene bisimide (PBI) units for electron transport, connected via a dodecyl linker. Sulfur and fluorine substituents were introduced to tune the energy levels and crystallinity of the conjugated polymers. The double-cable polymers adopt a "face-on" orientation in which the conjugated BDT backbone and the pendant PBI units have a preferential π-π stacking direction perpendicular to the substrate, favorable for interchain charge transport normal to the plane. The linear conjugated backbone acts as a scaffold for the crystallization of the PBI groups, to provide a double-cable nanophase separation of donor and acceptor phases. The optimized nanophase separation enables efficient exciton dissociation as well as charge transport as evidenced from the high-up to 80%-internal quantum efficiency for photon-to-electron conversion. In single-component organic solar cells, the double-cable polymers provide power conversion efficiency up to 4.18%. This is one of the highest performances in single-component organic solar cells. The nanophase-separated design can likely be used to achieve high-performance single-component organic solar cells.

Lipid-peptide-polymer conjugates and nanoparticles thereof

DOEpatents

Xu, Ting; Dong, He; Shu, Jessica

2015-06-02

The present invention provides a conjugate having a peptide with from about 10 to about 100 amino acids, wherein the peptide adopts a helical structure. The conjugate also includes a first polymer covalently linked to the peptide, and a hydrophobic moiety covalently linked to the N-terminus of the peptide, wherein the hydrophobic moiety comprises a second polymer or a lipid moiety. The present invention also provides helix bundles form by self-assembling the conjugates, and particles formed by self-assembling the helix bundles. Methods of preparing the helix bundles and particles are also provided.

π-Conjugated polymer anisotropic organogel nanofibrous assemblies for thermoresponsive photonic switches.

PubMed

Narasimha, Karnati; Jayakannan, Manickam

2014-11-12

The present work demonstrates one of the first examples of π-conjugated photonic switches (or photonic wave plates) based on the tailor-made π-conjugated polymer anisotropic organogel. New semicrystalline segmented π-conjugated polymers are designed with rigid aromatic oligophenylenevinylene π-core and flexible alkyl chain along the polymer backbone. These polymers are found to be self-assembled as semicrystalline or amorphous with respect to the number of carbon atoms in the alkyl units. These semicrystalline polymers produce organogels having nanofibrous morphology of 20 nm thickness with length up to 5 μm. The polymer organogel is aligned in a narrow glass capillary, and this anisotropic gel device is further demonstrated as photonic switches. The glass capillary device behaves as typical λ/4 photonic wave plates upon the illumination of the plane polarized light. The λ/4 photonic switching ability is found to be maximum at θ = 45° angle under the cross polarizers. The orthogonal arrangements of the gel capillaries produce dark and bright spots as on-and-off optical switches. Thermoreversibility of the polymer organogel (also its xerogel) was exploited to construct thermoresponsive photonic switches for the temperature window starting from 25 to 160 °C. The organic photonic switch concept can be adapted to large number of other π-conjugated materials for optical communication and storage.

Investigation of a thiolated polymer in gene delivery

NASA Astrophysics Data System (ADS)

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.

Solution-Phase Conformation and Dynamics of Conjugated Isoindigo-Based Donor–Acceptor Polymer Single Chains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Franklin L.; Farimani, Amir Barati; Gu, Kevin L.

Conjugated polymers are the key material in thin-film organic optoelectronic devices due to the versatility of these molecules combined with their semiconducting properties. A molecular-scale understanding of conjugated polymers is important to the optimization of the thin-film morphology. We examine the solution-phase behavior of conjugated isoindigo-based donor–acceptor polymer single chains of various chain lengths using atomistic molecular dynamics simulations. Our simulations elucidate the transition from a rod-like to a coil-like conformation from an analysis of normal modes and persistence length. In addition, we find another transition based on the solvent environment, contrasting the coil-like conformation in a good solvent withmore » a globule-like conformation in a poor solvent. Altogether, our results provide valuable insights into the transition between conformational regimes for conjugated polymers as a function of both the chain length and the solvent environment, which will help to accurately parametrize higher level models.« less

Solution-Phase Conformation and Dynamics of Conjugated Isoindigo-Based Donor–Acceptor Polymer Single Chains

DOE PAGES

Lee, Franklin L.; Farimani, Amir Barati; Gu, Kevin L.; ...

2017-10-25

Conjugated polymers are the key material in thin-film organic optoelectronic devices due to the versatility of these molecules combined with their semiconducting properties. A molecular-scale understanding of conjugated polymers is important to the optimization of the thin-film morphology. We examine the solution-phase behavior of conjugated isoindigo-based donor–acceptor polymer single chains of various chain lengths using atomistic molecular dynamics simulations. Our simulations elucidate the transition from a rod-like to a coil-like conformation from an analysis of normal modes and persistence length. In addition, we find another transition based on the solvent environment, contrasting the coil-like conformation in a good solvent withmore » a globule-like conformation in a poor solvent. Altogether, our results provide valuable insights into the transition between conformational regimes for conjugated polymers as a function of both the chain length and the solvent environment, which will help to accurately parametrize higher level models.« less

The Evolution of Thin-Film Structure in pi-Conjugated System: Implications for Devices

DTIC Science & Technology

2015-07-09

dependent, polymer self - assembly (Chem Matls, 2015). The results provide vital insights into factors leading to organized conjugated polymer nanostructures...34Liquid Crystalline Poly(3-hexylthiophene) Solutions Revisited: Role of Time- dependent Self - Assembly ", Chemistry of Materials (2015), 27(7), 2687-2694...period (if none, report none): For the first time, we demonstrated that π-conjugated polymers self - assemble and exhibit liquid crystal ordering

Synthesis and properties of a biodegradable polymer-drug conjugate: Methotrexate-poly(glycerol adipate).

PubMed

Suksiriworapong, Jiraphong; Taresco, Vincenzo; Ivanov, Delyan P; Styliari, Ioanna D; Sakchaisri, Krisada; Junyaprasert, Varaporn Buraphacheep; Garnett, Martin C

2018-07-01

Polymer-drug conjugates have been actively developed as potential anticancer drug delivery systems. In this study, we report the first polymer-anticancer drug conjugate with poly(glycerol adipate) (PGA) through the successful conjugation of methotrexate (MTX). MTX-PGA conjugates were controllably and simply fabricated by carbodiimide-mediated coupling reaction with various high molar ratios of MTX. The MTX-PGA conjugate self-assembled into nanoparticles with size dependent on the amount of conjugated MTX and the pH of medium. Change in particle size was attributed to steric hindrance and bulkiness inside the nanoparticle core and dissociation of free functional groups of the drug. The MTX-PGA nanoparticles were physically stable in media with pH range of 5-9 and ionic strength of up to 0.15 M NaCl and further chemically stable against hydrolysis in pH 7.4 medium over 30 days but enzymatically degradable to release unchanged free drug. Although 30%MTX-PGA nanoparticles exhibited only slightly less potency than free MTX in 791T cells in contrast to previously reported human serum albumin-MTX conjugates which had >300 times lower potency than free MTX. However, the MTX nanoparticles showed 7 times higher toxicity to Saos-2 cells than MTX. Together with the enzymic degradation experiments, these results suggest that with a suitable biodegradable polymer a linker moiety is not a necessary component. These easily synthesised PGA drug conjugates lacking a linker moiety could therefore be an effective new pathway for development of polymer drug conjugates. Copyright © 2018 Elsevier B.V. All rights reserved.

Near-infrared (NIR) emitting conjugated polymers for biomedical applications (Presentation Recording)

NASA Astrophysics Data System (ADS)

Repenko, Tatjana; Kuehne, Alexander J. C.

2015-10-01

Fluorescent biomedical markers of today such as dye-infiltrated colloids, microgels and quantum dots suffer from fast bleaching, lack surface functionality (for targets or pharmaceutical agents) and potentially leach heavy metals in case of quantum dots (e.g. Cd). By contrast, conjugated polymer particles are non-cytotoxic, exhibit reduced bleaching, as the entire particle consists of fluorophore, they are hydrophobic and show high quantum yields. Consequently, conjugated polymer particles represent ideal materials for biological applications and imaging. However currently, conjugated polymer particles for biomedical imaging usually lack near-infrared (NIR) emission and are polydisperse. Fluorescent agents with emission in the NIR spectrum are interesting for biomedical applications due to their low photo-damage towards biological species and the ability of NIR radiation to penetrate deep into biological tissue.. I will present the development and synthesis of new conjugated polymers particles with fluorescence in the NIR spectral region for bio-imaging and clinical diagnosis. The particle synthesis proceeds in a one-step Pd or Ni-catalyzed dispersion polymerization of functional NIR emitters. The resulting monodisperse conjugated polymer particles are obtained as a dispersion in a non-hazardous solvent. Different sizes in the sub-micrometer range with a narrow size distribution can be produced. Furthermore biological recognition motifs can be easily attached to the conjugated polymers via thiol-yne click-chemistry providing specific tumor targeting without quenching of the fluorescence. References [1] Kuehne AJC, Gather MC, Sprakel J., Nature Commun. 2012, 3, 1088. [2] Repenko T, Fokong S, De Laporte L, Go D, Kiessling F, Lammers T, Kuehne AJC.,Chem Commun 2015, accepted.

Systematic Analysis of Polymer Molecular Weight Influence on the Organic Photovoltaic Performance.

PubMed

Katsouras, Athanasios; Gasparini, Nicola; Koulogiannis, Chrysanthos; Spanos, Michael; Ameri, Tayebeh; Brabec, Christoph J; Chochos, Christos L; Avgeropoulos, Apostolos

2015-10-01

The molecular weight of an electron donor-conjugated polymer is as essential as other well-known parameters in the chemical structure of the polymer, such as length and the nature of any side groups (alkyl chains) positioned on the polymeric backbone, as well as their placement, relative strength, the ratio of the donor and acceptor moieties in the backbone of donor-acceptor (D-A)-conjugated polymers, and the arrangement of their energy levels for organic photovoltaic performance. Finding the "optimal" molecular weight for a specific conjugated polymer is an important aspect for the development of novel photovoltaic polymers. Therefore, it is evident that the chemistry of functional conjugated polymers faces major challenges and materials have to adopt a broad range of specifications in order to be established for high photovoltaic performance. In this review, the approaches followed for enhancing the molecular weight of electron-donor polymers are presented in detail, as well as how this influences the optoelectronic properties, charge transport properties, structural conformation, morphology, and the photovoltaic performance of the active layer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Folic acid conjugated cross-linked acrylic polymer (FA-CLAP) hydrogel for site specific delivery of hydrophobic drugs to cancer cells.

PubMed

Pillai, Jisha Jayadevan; Thulasidasan, Arun Kumar Theralikattu; Anto, Ruby John; Chithralekha, Devika Nandan; Narayanan, Ashwanikumar; Kumar, Gopalakrishnapillai Sankaramangalam Vinod

2014-07-15

The hydrogel based system is found to be rarely reported for the delivery of hydrophobic drug due to the incompatibility of hydrophilicity of the polymer network and the hydrophobicity of drug. This problem can be solved by preparing semi-interpenetrating network of cross-linked polymer for tuning the hydrophilicity so as to entrap the hydrophobic drugs. The current study is to develop a folic acid conjugated cross-linked pH sensitive, biocompatible polymeric hydrogel to achieve a site specific drug delivery. For that, we have synthesized a folic acid conjugated PEG cross-linked acrylic polymer (FA-CLAP) hydrogel and investigated its loading and release of curcumin. The formed polymer hydrogel was then conjugated with folic acid for the site specific delivery of curcumin to cancer cells and then further characterized and conducted the cell uptake and cytotoxicity studies on human cervical cancer cell lines (HeLa). In this study, we synthesized folic acid conjugated cross-linked acrylic hydrogel for the delivery of hydrophobic drugs to the cancer site. Poly (ethyleneglycol) (PEG) diacrylate cross-linked acrylic polymer (PAA) was prepared via inverse emulsion polymerization technique and later conjugated it with folic acid (FA-CLAP). Hydrophobic drug curcumin is entrapped into it and investigated the entrapment efficiency. Characterization of synthesized hydogel was done by using Fourier Transform-Infrared spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC). Polymerization and folate conjugation was confirmed by FT-IR spectroscopy. The release kinetics of drug from the entrapped form was studied which showed initial burst release followed by sustained release due to swelling and increased cross-linking. In vitro cytotoxicity and cell uptake studies were conducted in human cervical cancer (HeLa) cell lines. Results showed that curcumin entrapped folate conjugated cross-linked acrylic polymer (FA-CLAP) hydrogel showed higher cellular uptake than the non folate conjugated form. So this can be suggested as a better delivery system for site specific release of hydrophobic cancer drugs.

Structural and chemical aspects of HPMA copolymers as drug carriers.

PubMed

Ulbrich, Karel; Subr, Vladimír

2010-02-17

Synthetic strategies and chemical and structural aspects of the synthesis of HPMA copolymer conjugates with various drugs and other biologically active molecules are described and discussed in this chapter. The discussion is held from the viewpoint of design and structure of the polymer backbone and biodegradable spacer between a polymer and drug, structure and methods of attachment of the employed drugs to the carrier and structure and methods of conjugation with targeting moieties. Physicochemical properties of the water-soluble polymer-drug conjugates and polymer micelles including mechanisms of drug release are also discussed. Detailed description of biological behavior of the polymer-drug conjugates as well as application of the copolymers for surface modification and targeting of gene delivery vectors are not included, they are presented and discussed in separate chapters of this issue. Copyright 2009 Elsevier B.V. All rights reserved.

Polymer-Based Protein Engineering: Synthesis and Characterization of Armored, High Graft Density Polymer-Protein Conjugates.

PubMed

Carmali, Sheiliza; Murata, Hironobu; Cummings, Chad; Matyjaszewski, Krzysztof; Russell, Alan J

2017-01-01

Atom transfer radical polymerization (ATRP) from the surface of a protein can generate remarkably dense polymer shells that serve as armor and rationally tune protein function. Using straightforward chemistry, it is possible to covalently couple or display multiple small molecule initiators onto a protein surface. The chemistry is fine-tuned to be sequence specific (if one desires a single targeted site) at controlled density. Once the initiator is anchored on the protein surface, ATRP is used to grow polymers on protein surface, in situ. The technique is so powerful that a single-protein polymer conjugate molecule can contain more than 90% polymer coating by weight. If desired, stimuli-responsive polymers can be "grown" from the initiated sites to prepare enzyme conjugates that respond to external triggers such as temperature or pH, while still maintaining enzyme activity and stability. Herein, we focus mainly on the synthesis of chymotrypsin-polymer conjugates. Control of the number of covalently coupled initiator sites by changing the stoichiometric ratio between enzyme and the initiator during the synthesis of protein-initiator complexes allowed fine-tuning of the grafting density. For example, very high grafting density chymotrypsin conjugates were prepared from protein-initiator complexes to grow the temperature-responsive polymers, poly(N-isopropylacrylamide), and poly[N,N'-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate]. Controlled growth of polymers from protein surfaces enables one to predictably manipulate enzyme kinetics and stability without the need for molecular biology-dependent mutagenesis. © 2017 Elsevier Inc. All rights reserved.

The effects of vibronic coupling on the photophysics of pi-conjugated oligomers and polymers

NASA Astrophysics Data System (ADS)

Yamagata, Hajime

A theoretical model describing photophysics of pi-conjugated aggregates, such as molecular crystals and polymer thin films, is developed. A Holstein-like Hamiltonian expressed with a multi-particle basis set is used to evaluate absorption and photoluminescence (PL) spectra. An analysis with line strength ratio proves to be a powerful diagnostic tool to obtain additional spectral signatures with which to distinguish H- vs. J-aggregation. For the H-aggregates absorption peak ratio, A 0-0/A 0-1, diminishes as the excitonic coupling increases. Also the PL peak ratio, I 0-0/I 0-1, is zero at T=0K with no disorder and the value increases as temperature and disorder increase. By contrast the J-aggregates show the opposite trends. Furthermore we will show the PL peak ratio provides a direct measurement of the exciton coherence length for a linear J-aggregate and could be expressed as I0-0/I 0-1 = Ncoh/gamma2. We will also show that it is inversely proportional to square root of temperature (T-1/2). Applying our theory to the herringbone style oligoacene molecular crystals, we show the lowest singlet exciton states are highly influenced by charge transfer (CT) states and the well known energetic gap in two polarized absorption spectra, so called Davydov Splitting (DS), is a product of the interaction. We have successfully reproduced the DS for all three oligoacenes without any free parameters. Inspired by the CT contribution in oligoacene crystals, we further develop Wannier-Mott exciton model and apply to disorder-free polydiacetylene (PDA) quantum wires, which have been shown to be extremely emissive. We will show the quantum wire is a J-aggregate and we once again derive the peak ratio and the coherence size relation, I0-0/I 0-1 = kappaNcoh/gamma 2, where kappa is a prefactor close to unity. Typical photophysical properties of polymer pi-stacks such as those occurring in P3HT films are well explained by the simple linear H-aggregate model. However several groups have started seeing more J-like behaviors amongst "improved" (less disordered) polymer films such as increased values of A 0-0/A 0-1 and I 0-0/I 0-1 and higher radiative rates. With the new perception of a single polymer chain being a J-aggregate, we apply our new theory to pi-stack of polymer chains. We call this HJ-aggregate model since the interchain interaction induces H-aggregation. In the study we show a competition between intrachain and interchain interactions that leads to unique photophysical features. The new model is capable of explaining a wide range of polymer systems and most importantly the theory uncovers the mechanism of the improved polymer films; reducing disorder urges increasing intrachain reactions within each chain, thus enhancing more J-like spectral features.

Preparation and characterization of conjugated polyamidoamine-MPEG-methotrexate for potential drug delivery system

NASA Astrophysics Data System (ADS)

Mohd Sabri, Siti Noorzidah bt; Abu, Norhidayah; Mastor, Azreena; Hisham, Siti Farhana; Noorsal, Kartini

2012-07-01

Star polymers have unique characteristics due to their well-defined size and tailor ability which makes these polymers attractive candidates as carriers in drug delivery system applications. This work focuses on attaching a drug to the star polymer (polyamidoamine). The conjugation of polyamidoamine (PAMAM, generation 4) with methotrexate (MTX) (model drug) was studied in which monomethyl polyethylene glycol (MPEG) was used as a linker to reduce the toxicity of dendrimer. Conjugation starts with attaching the drug to the linker and followed by further conjugation with the polyamidoamine (PAMAM) dendrimer. The conjugation of PAMAM-PEG-MTX was confirmed through UV-Vis, FTIR, 1H NMR and DSC. The loading capacities and release profile of this conjugate were determined using 1H NMR and UV spectrometer.

Modification of Side Chains of Conjugated Molecules and Polymers for Charge Mobility Enhancement and Sensing Functionality.

PubMed

Liu, Zitong; Zhang, Guanxin; Zhang, Deqing

2018-06-19

Organic semiconductors have received increasing attentions in recent years because of their promising applications in various optoelectronic devices. The key performance metric for organic semiconductors is charge carrier mobility, which is governed by the electronic structures of conjugated backbones and intermolecular/interchain π-π interactions and packing in both microscopic and macroscopic levels. For this reason, more efforts have been paid to the design and synthesis of conjugated frameworks for organic semiconductors with high charge mobilities. However, recent studies manifest that appropriate modifications of side chains that are linked to conjugated frameworks can improve the intermolecular/interchain packing order and boost charge mobilities. In this Account, we discuss our research results in context of modification of side chains in organic semiconductors for charge mobility enhancement. These include the following: (i) The lengths of alkyl chains in sulfur-rich thiepin-fused heteroacences can dramatically influence the intermolecular arrangements and orbital overlaps, ushering in different hole mobilities. Inversely, the lamellar stacking modes of alkyl chains in naphthalene diimide (NDI) derivatives with tetrathiafulvalene (TTF) units are affected by the structures of conjugated cores. (ii) The steric hindrances owing to the bulky branching chains can be weakened by partial replacement of the branching alkyl chains with linear ones for diketopyrrolopyrrole (DPP)-based D (donor)-A (acceptor) conjugated polymers. Such modification of side chains makes the polymer backbones more planar and thus interchain packing order and charge mobilities are improved. The incorporation of hydrophilic tri(ethylene glycol) (TEG) chains into the polymers also leads to improved interchain packing order. In particular, the polymer in which TEG side chains are distributed uniformly exhibits relatively high charge mobility without thermal annealing. (iii) The incorporation of urea groups in the side chains induces the polymer chains to pack more orderly and form large domains because of the additional H-bonding among urea groups. Accordingly, thin film mobilities of the conjugated D-A polymers with side chains entailing urea groups are largely boosted in comparison with those of polymers of the same backbones with either branching alkyl chains or branching/linear alkyl chains. (iv) The torsions of branching alkyl chains in conjugated D-A polymers can be inhibited to some extent upon incorporation of tiny amount of NMe 4 I in the thin film. As a result, the polymer thin films with NMe 4 I exhibit improved crystallinity, and charge mobilities can be boosted by more than 20 times. (v) Side chains with functional groups in the conjugated polymers can endow the thin film field-effect transistors (FETs) with sensing functionality. FETs with the conjugated polymer with -COOH groups in the side chains show sensitive, selective, and fast responses toward ammonia and amines, while FETs with the ultrathin films of the polymer containing tetra(ethylene glycol) (TEEG) in the side chains can sense alcohol vapors (in particular ethanol vapor) sensitively and selectively with fast response.

Naphthobischalcogenadiazole Conjugated Polymers: Emerging Materials for Organic Electronics.

PubMed

Osaka, Itaru; Takimiya, Kazuo

2017-07-01

π-Conjugated polymers are an important class of materials for organic electronics. In the past decade, numerous polymers with donor-acceptor molecular structures have been developed and used as the active materials for organic devices, such as organic field-effect transistors (OFETs) and organic photovoltaics (OPVs). The choice of the building unit is the primary step for designing the polymers. Benzochalcogenadiazoles (BXzs) are one of the most familiar acceptor building units studied in this area. As their doubly fused system, naphthobischalcogenadiazoles (NXzs), i.e., naphthobisthiadiazole (NTz), naphthobisoxadiazole (NOz), and naphthobisselenadiazole (NSz) are emerging building units that provide interesting electronic properties and highly self-assembling nature for π-conjugated polymers. With these fruitful features, π-conjugated polymers based on these building units demonstrate great performances in OFETs and OPVs. In particular, in OPVs, NTz-based polymers have exhibited more than 10% efficiency, which is among the highest values reported so far. In this Progress Report, the synthesis, properties, and structures of NXzs and their polymers is summarized. The device performance is also highlighted and the structure-property relationships of the polymers are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quasi-Ballistic Carbon Nanotube Array Transistors with Current Density Exceeding Si and GaAs

DTIC Science & Technology

2016-09-02

performance of surfactant- encapsulated and conjugated polymer –wrapped CNTs in aligned arrays prepared by dielectrophoresis (20) and shear-casting (21); how... conjugated polymer poly[(9,9-dioctylfluorenyl- 2,7-diyl)-alt-co-(6,60-(2,20-bipyridine))] (PFO-BPy) in toluene to se- lectively wrap the semiconducting...Malenfant, J. Humes, J. Kroeger, A hybrid enrichment process combining conjugated polymer extraction and silica gel adsorption for high purity

Conjugated Polymer with Intrinsic Alkyne Units for Synergistically Enhanced Raman Imaging in Living Cells.

PubMed

Li, Shengliang; Chen, Tao; Wang, Yunxia; Liu, Libing; Lv, Fengting; Li, Zhiliang; Huang, Yanyi; Schanze, Kirk S; Wang, Shu

2017-10-16

Development of Raman-active materials with enhanced and distinctive Raman vibrations in the Raman-silent region (1800-2800 cm -1 ) is highly required for specific molecular imaging of living cells with high spatial resolution. Herein, water-soluble cationic conjugated polymers (CCPs), poly(phenylene ethynylene) (PPE) derivatives, are explored for use as alkyne-state-dependent Raman probes for living cell imaging due to synergetic enhancement effect of alkyne vibrations in Raman-silent region compared to alkyne-containing small molecules. The enhanced alkyne signals result from the integration of alkyne groups into the rigid backbone and the delocalized π-conjugated structure. PPE-based conjugated polymer nanoparticles (CPNs) were also prepared as Raman-responsive nanomaterials for distinct imaging application. This work opens a new way into the development of conjugated polymer materials for enhanced Raman imaging. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Smart linkers in polymer-drug conjugates for tumor-targeted delivery.

PubMed

Chang, Minglu; Zhang, Fang; Wei, Ting; Zuo, Tiantian; Guan, Yuanyuan; Lin, Guimei; Shao, Wei

2016-01-01

To achieve effective chemotherapy, many types of drug delivery systems have been developed for the specific environments in tumor tissues. Polymer-drug conjugates are increasingly used in tumor therapy due to several significant advantages over traditional delivery systems. In the fabrication of polymer-drug conjugates, a smart linker is an important component that joins two fragments or molecules together and can be cleared by a specific stimulus, which results in targeted drug delivery and controlled release. By regulating the conjugation between the drug and the nanocarriers, stimulus-sensitive systems based on smart linkers can offer high payloads, certified stability, controlled release and targeted delivery. In this review, we summarize the current state of smart linkers (e.g. disulfide, hydrazone, peptide, azo) used recently in various polymer-drug conjugate-based delivery systems with a primary focus on their sophisticated design principles and drug delivery mechanisms as well as in vivo processes.

All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers.

PubMed

Zhou, Nanjia; Dudnik, Alexander S; Li, Ting I N G; Manley, Eric F; Aldrich, Thomas J; Guo, Peijun; Liao, Hsueh-Chung; Chen, Zhihua; Chen, Lin X; Chang, Robert P H; Facchetti, Antonio; Olvera de la Cruz, Monica; Marks, Tobin J

2016-02-03

The influence of the number-average molecular weight (Mn) on the blend film morphology and photovoltaic performance of all-polymer solar cells (APSCs) fabricated with the donor polymer poly[5-(2-hexyldodecyl)-1,3-thieno[3,4-c]pyrrole-4,6-dione-alt-5,5-(2,5-bis(3-dodecylthiophen-2-yl)thiophene)] (PTPD3T) and acceptor polymer poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2); N2200) is systematically investigated. The Mn effect analysis of both PTPD3T and N2200 is enabled by implementing a polymerization strategy which produces conjugated polymers with tunable Mns. Experimental and coarse-grain modeling results reveal that systematic Mn variation greatly influences both intrachain and interchain interactions and ultimately the degree of phase separation and morphology evolution. Specifically, increasing Mn for both polymers shrinks blend film domain sizes and enhances donor-acceptor polymer-polymer interfacial areas, affording increased short-circuit current densities (Jsc). However, the greater disorder and intermixed feature proliferation accompanying increasing Mn promotes charge carrier recombination, reducing cell fill factors (FF). The optimized photoactive layers exhibit well-balanced exciton dissociation and charge transport characteristics, ultimately providing solar cells with a 2-fold PCE enhancement versus devices with nonoptimal Mns. Overall, it is shown that proper and precise tuning of both donor and acceptor polymer Mns is critical for optimizing APSC performance. In contrast to reports where maximum power conversion efficiencies (PCEs) are achieved for the highest Mns, the present two-dimensional Mn optimization matrix strategy locates a PCE "sweet spot" at intermediate Mns of both donor and acceptor polymers. This study provides synthetic methodologies to predictably access conjugated polymers with desired Mn and highlights the importance of optimizing Mn for both polymer components to realize the full potential of APSC performance.

Direct observation of backbone planarization via side-chain alignment in single bulky-substituted polythiophenes

NASA Astrophysics Data System (ADS)

Raithel, Dominic; Simine, Lena; Pickel, Sebastian; Schötz, Konstantin; Panzer, Fabian; Baderschneider, Sebastian; Schiefer, Daniel; Lohwasser, Ruth; Köhler, Jürgen; Thelakkat, Mukundan; Sommer, Michael; Köhler, Anna; Rossky, Peter J.; Hildner, Richard

2018-03-01

The backbone conformation of conjugated polymers affects, to a large extent, their optical and electronic properties. The usually flexible substituents provide solubility and influence the packing behavior of conjugated polymers in films or in bad solvents. However, the role of the side chains in determining and potentially controlling the backbone conformation, and thus the optical and electronic properties on the single polymer level, is currently under debate. Here, we investigate directly the impact of the side chains by studying the bulky-substituted poly(3-(2,5-dioctylphenyl)thiophene) (PDOPT) and the common poly(3-hexylthiophene) (P3HT), both with a defined molecular weight and high regioregularity, using low-temperature single-chain photoluminescence (PL) spectroscopy and quantum-classical simulations. Surprisingly, the optical transition energy of PDOPT is significantly (˜2,000 cm‑1 or 0.25 eV) red-shifted relative to P3HT despite a higher static and dynamic disorder in the former. We ascribe this red shift to a side-chain induced backbone planarization in PDOPT, supported by temperature-dependent ensemble PL spectroscopy. Our atomistic simulations reveal that the bulkier 2,5-dioctylphenyl side chains of PDOPT adopt a clear secondary helical structural motif and thus protect conjugation, i.e., enforce backbone planarity, whereas, for P3HT, this is not the case. These different degrees of planarity in both thiophenes do not result in different conjugation lengths, which we found to be similar. It is rather the stronger electronic coupling between the repeating units in the more planar PDOPT which gives rise to the observed spectral red shift as well as to a reduced calculated electron‑hole polarization.

Photophysical Diversity of Water-Soluble Fluorescent Conjugated Polymers Induced by Surfactant Stabilizers for Rapid and Highly Selective Determination of 2,4,6-Trinitrotoluene Traces.

PubMed

Alizadeh, Naader; Akbarinejad, Alireza; Ghoorchian, Arash

2016-09-21

The increasing application of fluorescence spectroscopy in development of reliable sensing platforms has triggered a lot of research interest for the synthesis of advanced fluorescent materials. Herein, we report a simple, low-cost strategy for the synthesis of a series of water-soluble conjugated polymer nanoparticles with diverse emission range using cationic (hexadecyltrimethylammonium bromide, CTAB), anionic (sodium dodecylbenzenesulfonate, SDBS), and nonionic (TX114) surfactants as the stabilizing agents. The role of surfactant type on the photophisical and sensing properties of resultant polymers has been investigated using dynamic light scattering (DLS), FT-IR, UV-vis, fluorescence, and energy dispersive X-ray (EDS) spectroscopies. The results show that the surface polarity, size, and spectroscopic and sensing properties of conjugated polymers could be well controlled by the proper selection of the stabilizer type. The fluorescent conjugated polymers exhibited fluorescence quenching toward nitroaromatic compounds. Further studies on the fluorescence properties of conjugated polymers revealed that the emission of the SDBS stabilized polymer, N-methylpolypyrrole-SDBS (NMPPY-SDBS), is strongly quenched by 2,4,6-trinitrotoluene molecule with a large Stern -Volmer constant of 59 526 M(-1) and an excellent detection limit of 100 nM. UV-vis and cyclic voltammetry measurements unveiled that fluorescence quenching occurs through a charge transfer mechanism between electron rich NMPPY-SDBS and electron deficient 2,4,6-trinitrotoluene molecules. Finally, the as-prepared conjugated polymer and approach were successfully applied to the determination of 2,4,6-trinitrotoluene in real water samples.

Thiolated polymers: synthesis and in vitro evaluation of polymer-cysteamine conjugates.

PubMed

Bernkop-Schnürch, A; Clausen, A E; Hnatyszyn, M

2001-09-11

The purpose of the present study was to synthesize and characterize novel thiolated polymers. Mediated by a carbodiimide cysteamine was covalently linked to sodium carboxymethylcellulose (CMC) and polycarbophil (PCP). The resulting CMC-cysteamine conjugates displayed 77.9+/-6.7 and 365.1+/-8.7 micromol thiol groups per gram of polymer, whereas the PCP-cysteamine conjugates showed 26.3+/-1.9 and 122.7+/-3.8 micromol thiol groups per gram of polymer (mean+/-S.D.; n=3). In aqueous solutions above pH 5.0 both modified polymers were capable of forming inter- and/or intra-molecular disulfide bonds. The reaction velocity of this oxidation process was accelerated with a decrease in the proton concentration. The oxidation proceeded more rapidly within thiolated CMC than within thiolated PCP. Permeation studies carried out in Ussing-type chambers with freshly excised intestinal mucosa from guinea pigs utilizing sodium fluorescein as model drug for the paracellular uptake revealed an enhancement ratio (R=P(app) (conjugate)/P(app) (control)) of 1.15 and 1.41 (mean+/-S.D.; n=3) for the higher thiolated CMC-cysteamine (0.5%; m/v) and PCP-cysteamine conjugate (1.0%; m/v), respectively. The decrease in the transepithelial electrical resistance values was in good correlation with the enhancement ratios. Due to a high crosslinking tendency by the formation of disulfide bonds stabilizing drug carrier systems based on thiolated polymers and a permeation enhancing effect, CMC- and PCP-cysteamine conjugates represent promising excipients for the development of novel drug delivery systems.

Conjugated Polymers in Bioelectronics.

PubMed

Inal, Sahika; Rivnay, Jonathan; Suiu, Andreea-Otilia; Malliaras, George G; McCulloch, Iain

2018-06-19

The emerging field of organic bioelectronics bridges the electronic world of organic-semiconductor-based devices with the soft, predominantly ionic world of biology. This crosstalk can occur in both directions. For example, a biochemical reaction may change the doping state of an organic material, generating an electronic readout. Conversely, an electronic signal from a device may stimulate a biological event. Cutting-edge research in this field results in the development of a broad variety of meaningful applications, from biosensors and drug delivery systems to health monitoring devices and brain-machine interfaces. Conjugated polymers share similarities in chemical "nature" with biological molecules and can be engineered on various forms, including hydrogels that have Young's moduli similar to those of soft tissues and are ionically conducting. The structure of organic materials can be tuned through synthetic chemistry, and their biological properties can be controlled using a variety of functionalization strategies. Finally, organic electronic materials can be integrated with a variety of mechanical supports, giving rise to devices with form factors that enable integration with biological systems. While these developments are innovative and promising, it is important to note that the field is still in its infancy, with many unknowns and immense scope for exploration and highly collaborative research. The first part of this Account details the unique properties that render conjugated polymers excellent biointerfacing materials. We then offer an overview of the most common conjugated polymers that have been used as active layers in various organic bioelectronics devices, highlighting the importance of developing new materials. These materials are the most popular ethylenedioxythiophene derivatives as well as conjugated polyelectrolytes and ion-free organic semiconductors functionalized for the biological interface. We then discuss several applications and operation principles of state-of-the-art bioelectronics devices. These devices include electrodes applied to sense/trigger electrophysiological activity of cells as well as electrolyte-gated field-effect and electrochemical transistors used for sensing of biochemical markers. Another prime application example of conjugated polymers is cell actuators. External modulation of the redox state of the underlying conjugated polymer films controls the adhesion behavior and viability of cells. These smart surfaces can be also designed in the form of three-dimensional architectures because of the processability of conjugated polymers. As such, cell-loaded scaffolds based on electroactive polymers enable integrated sensing or stimulation within the engineered tissue itself. A last application example is organic neuromorphic devices, an alternative computing architecture that takes inspiration from biology and, in particular, from the way the brain works. Leveraging ion redistribution inside a conjugated polymer upon application of an electrical field and its coupling with electronic charges, conjugated polymers can be engineered to act as artificial neurons or synapses with complex, history-dependent behavior. We conclude this Account by highlighting main factors that need to be considered for the design of a conjugated polymer for applications in bioelectronics-although there can be various figures of merit given the broad range of applications, as emphasized in this Account.

Side-Chain Effects on the Thermoelectric Properties of Fluorene-Based Copolymers.

PubMed

Liang, Ansheng; Zhou, Xiaoyan; Zhou, Wenqiao; Wan, Tao; Wang, Luhai; Pan, Chengjun; Wang, Lei

2017-09-01

Three conjugated polymers with alkyl chains of different lengths are designed and synthesized, and their structure-property relationship as organic thermoelectric materials is systematically elucidated. All three polymers show similar photophysical properties, thermal properties, and mechanical properties; however, their thermoelectric performance is influenced by the length of their side chains. The length of the alkyl chain significantly influences the electrical conductivity of the conjugated polymers, and polymers with a short alkyl chain exhibit better conductivity than those with a long alkyl chain. The length of the alkyl chain has little effect on the Seebeck coefficient. Only a slight increase in the Seebeck coefficient is observed with the increasing length of the alkyl chain. The purpose of this study is to provide comprehensive insight into fine-tuning the thermoelectric properties of conjugated polymers as a function of side-chain engineering, thereby providing a novel perspective into the design of high-performance thermoelectric conjugated polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid-phase synthesis of protein-polymers on reversible immobilization supports.

PubMed

Murata, Hironobu; Carmali, Sheiliza; Baker, Stefanie L; Matyjaszewski, Krzysztof; Russell, Alan J

2018-02-27

Facile automated biomacromolecule synthesis is at the heart of blending synthetic and biologic worlds. Full access to abiotic/biotic synthetic diversity first occurred when chemistry was developed to grow nucleic acids and peptides from reversibly immobilized precursors. Protein-polymer conjugates, however, have always been synthesized in solution in multi-step, multi-day processes that couple innovative chemistry with challenging purification. Here we report the generation of protein-polymer hybrids synthesized by protein-ATRP on reversible immobilization supports (PARIS). We utilized modified agarose beads to covalently and reversibly couple to proteins in amino-specific reactions. We then modified reversibly immobilized proteins with protein-reactive ATRP initiators and, after ATRP, we released and analyzed the protein polymers. The activity and stability of PARIS-synthesized and solution-synthesized conjugates demonstrated that PARIS was an effective, rapid, and simple method to generate protein-polymer conjugates. Automation of PARIS significantly reduced synthesis/purification timelines, thereby opening a path to changing how to generate protein-polymer conjugates.

Methyllithium-Doped Naphthyl-Containing Conjugated Microporous Polymer with Enhanced Hydrogen Storage Performance.

PubMed

Xu, Dan; Sun, Lei; Li, Gang; Shang, Jin; Yang, Rui-Xia; Deng, Wei-Qiao

2016-06-01

Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium-doped naphthyl-containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol(-1) and the methyllithium-doped naphthyl-containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150 % enhancement compared with its counterpart naphthyl-containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Nanjia; Dudnik, Alexander S.; Li, Ting I. N. G.

2016-01-21

The influence of the number-average molecular weight (Mn) on the blend film morphology and photovoltaic performance of all-polymer solar cells (APSCs) fabricated with the donor polymer poly[5-(2-hexyldodecyl)-1,3-thieno[3,4-c]pyrrole-4,6-dione-alt-5,5-(2,5-bis(3-dodecylthiophen-2-yl)thiophene)] (PTPD3T) and acceptor polymer poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2); N2200) is systematically investigated. The Mn effect analysis of both PTPD3T and N2200 is enabled by implementing a polymerization strategy which produces conjugated polymers with tunable Mns. Experimental and coarse-grain modeling results reveal that systematic Mn variation greatly influences both intrachain and interchain interactions and ultimately the degree of phase separation and morphology evolution. Specifically, increasing Mn for both polymers shrinks blend film domain sizes and enhancesmore » donor–acceptor polymer–polymer interfacial areas, affording increased short-circuit current densities (Jsc). However, the greater disorder and intermixed feature proliferation accompanying increasing Mn promotes charge carrier recombination, reducing cell fill factors (FF). The optimized photoactive layers exhibit well-balanced exciton dissociation and charge transport characteristics, ultimately providing solar cells with a 2-fold PCE enhancement versus devices with nonoptimal Mns. Overall, it is shown that proper and precise tuning of both donor and acceptor polymer Mns is critical for optimizing APSC performance. In contrast to reports where maximum power conversion efficiencies (PCEs) are achieved for the highest Mns, the present two-dimensional Mn optimization matrix strategy locates a PCE “sweet spot” at intermediate Mns of both donor and acceptor polymers. This study provides synthetic methodologies to predictably access conjugated polymers with desired Mn and highlights the importance of optimizing Mn for both polymer components to realize the full potential of APSC performance.« less

Polysaccharide-Modified Synthetic Polymeric Biomaterials

PubMed Central

Baldwin, Aaron D.; Kiick, Kristi L.

2010-01-01

This review presents an overview of polysaccharide-conjugated synthetic polymers and their use in tissue-engineered scaffolds and drug-delivery applications. This topic will be divided into four categories: (1) polymeric materials modified with non-mammalian polysaccharides such as alginate, chitin, and dextran; (2) polymers modified with mammalian polysaccharides such as hyaluronan, chondroitin sulfate, and heparin; (3) multi-polysaccharide-derivatized polymer conjugate systems; and (4) polymers containing polysaccharide-mimetic molecules. Each section will discuss relevant conjugation techniques, analysis, and the impact of these materials as micelles, particles, or hydrogels used in in-vitro and in-vivo biomaterial applications. PMID:20091875

Enhanced photophysics of conjugated polymers

DOEpatents

Chen, Liaohai [Argonne, IL; Xu, Su [Santa Clara, CA; McBranch, Duncan [Santa Fe, NM; Whitten, David [Santa Fe, NM

2003-05-27

The addition of oppositely charged surfactant to fluorescent ionic conjugated polymer forms a polymer-surfactant complex that exhibits at least one improved photophysical property. The conjugated polymer is a fluorescent ionic polymer that typically has at least one ionic side chain or moiety that interacts with the specific surfactant selected. The photophysical property improvements may include increased fluorescence quantum efficiency, wavelength-independent emission and absorption spectra, and more stable fluorescence decay kinetics. The complexation typically occurs in a solution of a polar solvent in which the polymer and surfactant are soluble, but it may also occur in a mixture of solvents. The solution is commonly prepared with a surfactant molecule:monomer repeat unit of polymer ratio ranging from about 1:100 to about 1:1. A polymer-surfactant complex precipitate is formed as the ratio approaches 1:1. This precipitate is recoverable and usable in many forms.

Transformation of regioregular organotitanium polymers into group 16 heterole-containing π-conjugated materials.

PubMed

Nishiyama, Hiroki; Kino, Tomoko; Tomita, Ikuyoshi

2012-04-13

Regioregular organometallic polymers with titanacyclopentadiene units, obtained from terminal diynes and a low-valent titanium complex, were subjected to reactions with disulfur dichloride and selenium (I) chloride to give π-conjugated polymers with thiophene and selenophene units in the main chain in 63% and 86% yields. Their number-average molecular weights were estimated as 4300 and 5700, respectively. Both polymers were found to be fully π-conjugated and their HOMO energy levels were remarkably high (-5.3 eV and -5.0 eV for thiophene- and selenophene-containing polymers, respectively) as supported by their UV-vis absorption spectra and CV analyses. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Review on the targeted conjugation of anticancer drugs doxorubicin and tamoxifen with synthetic polymers for drug delivery.

PubMed

Sanyakamdhorn, S; Agudelo, D; Tajmir-Riahi, H A

2017-08-01

In this review, the binding and loading efficacy (LE) of anticancer drugs doxorubicin (DOX), tamoxifen (Tam) and its metabolites 4-hydroxytamoxifen (4-Hydroxytam) and endoxifen (Endox) with several synthetic polymers poly(ethylene glycol) (PEG), methoxypoly (ethylene glycol) polyamidoamine (mPEG-PAMAM-G3), and polyamidoamine (PAMAM-G4) dendrimers were compared in aqueous solution at pH 7.4. The results of multiple spectroscopic methods, transmission electron microscopy (TEM) and molecular modeling of conjugated drug-polymer were examined. Structural analysis showed that drug-polymer conjugation occurs mainly via H-bonding and hydrophobic contacts. The order of binding is PAMAM-G4 > mPEG-PAMAM-G3 > PEG-6000 with 4-hydroxttamoxifen forming more stable conjugate than tamoxifen and endoxifen. Doxorubicin shows stronger affinity for PAMAM-G4 than tamoxifen and its metabolites. The drug LE was 30-55%. TEM showed significant changes in the carrier morphology upon drug encapsulation. Modeling also showed that drug is located in the surface and in the internal cavities of PAMAM with DOX forming more stable polymer conjugates.

Patterning of conjugated polymers for organic optoelectronic devices.

PubMed

Xu, Youyong; Zhang, Fan; Feng, Xinliang

2011-05-23

Conjugated polymers have been attracting more and more attention because they possess various novel electrical, magnetical, and optical properties, which render them useful in modern organic optoelectronic devices. Due to their organic nature, conjugated polymers are light-weight and can be fabricated into flexible appliances. Significant research efforts have been devoted to developing new organic materials to make them competitive with their conventional inorganic counterparts. It is foreseeable that when large-scale industrial manufacture of the devices made from organic conjugated polymers is feasible, they would be much cheaper and have more functions. On one hand, in order to improve the performance of organic optoelectronic devices, it is essential to tune their surface morphologies by techniques such as patterning. On the other hand, patterning is the routine requirement for device processing. In this review, the recent progress in the patterning of conjugated polymers for high-performance optoelectronic devices is summarized. Patterning based on the bottom-up and top-down methods are introduced. Emerging new patterning strategies and future trends for conventional patterning techniques are discussed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent Advances in Conjugated Polymer Materials for Disease Diagnosis.

PubMed

Lv, Fengting; Qiu, Tian; Liu, Libing; Ying, Jianming; Wang, Shu

2016-02-10

The extraordinary optical amplification and light-harvesting properties of conjugated polymers impart sensing systems with higher sensitivity, which meets the primary demands of early cancer diagnosis. Recent advances in the detection of DNA methylation and mutation with polyfluorene derivatives based fluorescence resonance energy transfer (FRET) as a means to modulate fluorescent responses attest to the great promise of conjugated polymers as powerful tools for the clinical diagnosis of diseases. To facilitate the ever-changing needs of diagnosis, the development of detection approaches and FRET signal analysis are highlighted in this review. Due to their exceptional brightness, excellent photostability, and low or absent toxicity, conjugated polymers are verified as superior materials for in-vivo imaging, and provide feasibility for future clinical molecular-imaging applications. The integration of conjugated polymers with clinical research has shown profound effects on diagnosis for the early detection of disease-related biomarkers, as well as in-vivo imaging, which leads to a multidisciplinary scientific field with perspectives in both basic research and application issues. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photo-assisted generation of phospholipid polymer substrates for regiospecific protein conjugation and control of cell adhesion.

PubMed

Tanaka, Masako; Iwasaki, Yasuhiko

2016-08-01

Novel photo-reactive phospholipid polymers were synthesized for use in the preparation of nonfouling surfaces with protein conjugation capacity. Poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-ran-N-methacryloyl-(l)-tyrosinemethylester (MAT)] (P(MPC/MAT)) was synthesized by conventional radical polymerization, with the MAT units capable of being oxidized by 254nm UV irradiation. Because of this photo-oxidation, active species such as catechol and quinone were alternately generated in the copolymer. A silicon wafer was subjected to surface modification through spin coating of P(MPC/MAT) from an aqueous solution for use as a model substrate. The surface was then irradiated several times with UV light. The thickness of the polymer layers formed on the Si wafers was influenced by various parameters such as polymer concentration, UV irradiation time, and composition of the MAT units in P(MPC/MAT). Oxidized MAT units were advantageous not only for polymer adhesion to a solid surface but also for protein conjugation with the adhered polymers. The amount of protein immobilized on UV-irradiated P(MPC/MAT) was dependent on the composition of the MAT units in the polymer. Furthermore, it was confirmed that protein immobilization on the polymer occurred through the oxidized MAT units because the protein adsorption was significantly reduced upon blocking these units through pretreatment with glycine. Conjugation of regiospecific protein could also be achieved through the use of a photomask. In addition, nonspecific protein adsorption was reduced on the non-irradiated regions whose surface was covered with physisorbed P(MPC/MAT). Therefore, P(MPC/MAT) can be used in the preparation of nonfouling substrates, which enable micrometer-sized manipulation of proteins through photo-irradiation. Function of proteins immobilized on MPC copolymers was also confirmed by cell adhesion test. As such, photo-reactive MPC copolymers are suitable for performing controlled protein conjugation and preparing polymer-protein hybrid platforms for use in biomedical and diagnostic devices. Novel photo-reactive phospholipid polymers have been synthesized for immobilization on solid surfaces and regiospecific protein conjugation. Tyrosine residues embedded in 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymers could be photo-oxidized, resulting in polymers able to form layers on a solid surface and conjugate with proteins. Moreover, nonspecific biofouling on the surface significantly reduced when the oxidized tyrosine units in the polymer layers were blocked. Upon UV irradiation through a photomask, the UV-exposed tyrosine units were selectively oxidized, forming the only specific regions in which protein conjugation could occur. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Conjugated ionomers for photovoltaic applications: electric field driven charge separation in organic photovoltaics. Final Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lonergan, Mark

Final technical report for Conjugated ionomers for photovoltaic applications, electric field driven charge separation in organic photovoltaics. The central goal of the work we completed was been to understand the photochemical and photovoltaic properties of ionically functionalized conjugated polymers (conjugated ionomers or polyelectrolytes) and energy conversion systems based on them. We primarily studied two classes of conjugated polymer interfaces that we developed based either upon undoped conjugated polymers with an asymmetry in ionic composition (the ionic junction) or doped conjugated polymers with an asymmetry in doping type (the p-n junction). The materials used for these studies have primarily been themore » polyacetylene ionomers. We completed a detailed study of p-n junctions with systematically varying dopant density, photochemical creation of doped junctions, and experimental and theoretical work on charge transport and injection in polyacetylene ionomers. We have also completed related work on the use of conjugated ionomers as interlayers that improve the efficiency or organic photovoltaic systems and studied several important aspects of the chemistry of ionically functionalized semiconductors, including mechanisms of so-called "anion-doping", the formation of charge transfer complexes with oxygen, and the synthesis of new polyfluorene polyelectrolytes. We also worked worked with the Haley group at the University of Oregon on new indenofluorene-based organic acceptors.« less

Dendritic polymer imaging systems for the evaluation of conjugate uptake and cleavage

NASA Astrophysics Data System (ADS)

Krüger, Harald R.; Nagel, Gregor; Wedepohl, Stefanie; Calderón, Marcelo

2015-02-01

Fluorescent turn-on probes combined with polymers have a broad range of applications, e.g. for intracellular sensing of ions, small molecules, or DNA. In the field of polymer therapeutics, these probes can be applied to extend the in vitro characterization of novel conjugates beyond cytotoxicity and cellular uptake studies. This is particularly true in cases in which polymer conjugates contain drugs attached by cleavable linkers. Better information on the intracellular linker cleavage and drug release would allow a faster evaluation and optimization of novel polymer therapeutic concepts. We therefore developed a fluorescent turn-on probe that enables direct monitoring of pH-mediated cleavage processes over time. This is achieved by exploiting the fluorescence resonance energy transfer (FRET) between two dyes that have been coupled to a dendritic polymer. We demonstrate the use of this probe to evaluate polymer uptake and intracellular release of cargo in a cell based microplate assay that is suitable for high throughput screening.Fluorescent turn-on probes combined with polymers have a broad range of applications, e.g. for intracellular sensing of ions, small molecules, or DNA. In the field of polymer therapeutics, these probes can be applied to extend the in vitro characterization of novel conjugates beyond cytotoxicity and cellular uptake studies. This is particularly true in cases in which polymer conjugates contain drugs attached by cleavable linkers. Better information on the intracellular linker cleavage and drug release would allow a faster evaluation and optimization of novel polymer therapeutic concepts. We therefore developed a fluorescent turn-on probe that enables direct monitoring of pH-mediated cleavage processes over time. This is achieved by exploiting the fluorescence resonance energy transfer (FRET) between two dyes that have been coupled to a dendritic polymer. We demonstrate the use of this probe to evaluate polymer uptake and intracellular release of cargo in a cell based microplate assay that is suitable for high throughput screening. Electronic supplementary information (ESI) available: Including detailed synthetic procedures of the dye and conjugate synthesis, as well as cellular uptake and inhibitor studies. See DOI: 10.1039/c4nr04467c

Comparison of Hydrazone Heterobifunctional Crosslinking Agents for Reversible Conjugation of Thiol-Containing Chemistry

PubMed Central

Christie, R. James; Anderson, Diana J.; Grainger, David W.

2010-01-01

Reversible covalent conjugation chemistries that allow site- and condition-specific coupling and uncoupling reactions are attractive components in nanotechnologies, bioconjugation methods, imaging and drug delivery systems. Here, we compare three heterobifunctional crosslinkers, containing both thiol- and amine- reactive chemistry, to form pH-labile hydrazones with hydrazide derivatives of the known and often published water-soluble polymer, poly[N-(2-hydroxypropyl methacrylamide)] (pHPMA), while subsequently coupling thiol-containing molecules to the crosslinker via maleimide addition. Two novel crosslinkers were prepared from the popular heterobifunctional crosslinking agent, succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC), modified to contain either terminal aldehyde groups (i.e., 1-(N-3-propanal)-4-(N-maleimidomethyl) cyclohexane carboxamide, PMCA) or methylketone groups (i.e., 1-(N-3-butanone)-4-(N-maleimidomethyl) cyclohexane carboxamide, BMCA). A third crosslinking agent was the commercially available N-4-acetylphenyl maleimide (APM). PMCA and BMCA exhibited excellent reactivity towards hydrazide-derivatized pHPMA with essentially complete hydrazone conjugation to polymer reactive sites, while APM coupled only ~ 60% of available reactive sites on the polymer despite a 3-fold molar excess relative to polymer hydrazide groups. All polymer hydrazone conjugates bearing these bifunctional agents were then further reacted with thiol-modified tetramethylrhodamine dye, confirming crosslinker maleimide reactivity after initial hydrazone polymer conjugation. Incubation of dye-labeled polymer conjugates in phosphate buffered saline at 37°C showed that hydrazone coupling resulting from APM exhibited the greatest difference in stability between pH 7.4 and 5.0, with hydrolysis and dye release increased at pH 5.0 over a 24hr incubation period. Polymer conjugates bearing hydrazones formed from crosslinker BMCA exhibited intermediate stability with hydrolysis much greater at pH 5.0 at early time points, but hydrolysis at pH 7.4 was significant after 5 hrs. Hydrazones formed with the PMCA crosslinker showed no difference in release rates at pH 7.4 and 5.0. PMID:20695431

Intracellular delivery and trafficking dynamics of a lymphoma-targeting antibody-polymer conjugate.

PubMed

Berguig, Geoffrey Y; Convertine, Anthony J; Shi, Julie; Palanca-Wessels, Maria Corinna; Duvall, Craig L; Pun, Suzie H; Press, Oliver W; Stayton, Patrick S

2012-12-03

Ratiometric fluorescence and cellular fractionation studies were employed to characterize the intracellular trafficking dynamics of antibody-poly(propylacrylic acid) (PPAA) conjugates in CD22+ RAMOS-AW cells. The HD39 monoclonal antibody (mAb) directs CD22-dependent, receptor-mediated uptake in human B-cell lymphoma cells, where it is rapidly trafficked to the lysosomal compartment. To characterize the intracellular-release dynamics of the polymer-mAb conjugates, HD39-streptavidin (HD39/SA) was dual-labeled with pH-insensitive Alexa Fluor 488 and pH-sensitive pHrodo fluorophores. The subcellular pH distribution of the HD39/SA-polymer conjugates was quantified as a function of time by live-cell fluorescence microscopy, and the average intracellular pH value experienced by the conjugates was also characterized as a function of time by flow cytometry. PPAA was shown to alter the intracellular trafficking kinetics strongly relative to HD39/SA alone or HD39/SA conjugates with a control polymer, poly(methacryclic acid) (PMAA). Subcellular trafficking studies revealed that after 6 h, only 11% of the HD39/SA-PPAA conjugates had been trafficked to acidic lysosomal compartments with values at or below pH 5.6. In contrast, the average intracellular pH of HD39/SA alone dropped from 6.7 ± 0.2 at 1 h to 5.6 ± 0.5 after 3 h and 4.7 ± 0.6 after 6 h. Conjugation of the control polymer PMAA to HD39/SA showed an average pH drop similar to that of HD39/SA. Subcellular fractionation studies with tritium-labeled HD39/SA demonstrated that after 6 h, 89% of HD39/SA was associated with endosomes (Rab5+) and lysosomes (Lamp2+), while 45% of HD39/SA-PPAA was translocated to the cytosol (lactate dehydrogenase+). These results demonstrate the endosomal-releasing properties of PPAA with antibody-polymer conjugates and detail their intracellular trafficking dynamics and subcellular compartmental distributions over time.

Thiolated polymers--thiomers: development and in vitro evaluation of chitosan-thioglycolic acid conjugates.

PubMed

Kast, C E; Bernkop-Schnürch, A

2001-09-01

The aim of this study was to improve mucoadhesive properties of chitosan by the covalent attachment of thiol moieties to this cationic polymer. Mediated by a carbodiimide, thioglycolic acid (TGA) was covalently attached to chitosan. This was achieved by the formation of amide bonds between the primary amino groups of the polymer and the carboxylic acid group of TGA. Dependent on the pH-value and the weight ratio of polymer to TGA during the coupling reaction the resulting thiolated polymers, the so-called thiomers, displayed 6.58, 9.88, 27.44, and 38.23 micromole thiol groups per gram polymer. Tensile studies carried out with these chitosan-TGA conjugates on freshly excised porcine intestinal mucosa demonstrated a 6.3-, 8.6-, 8.9-, and 10.3-fold increase in the total work of adhesion (TWA) compared to the unmodified polymer, respectively. In contrast, the combination of chitosan and free unconjugated TGA showed almost no mucoadhesion. These data were in good correlation with further results obtained by another mucoadhesion test demonstrating a prolonged residence time of thiolated chitosan on porcine mucosa. The swelling behavior of all conjugates was thereby exactly in the same range as for an unmodified polymer pretreated in the same way. Furthermore, it could be shown that chitosan-TGA conjugates are still biodegradable by the glycosidase lysozyme. According to these results. chitosan-TGA conjugates represent a promising tool for the development of mucoadhesive drug delivery systems.

Lymphatic trafficking kinetics and near-infrared imaging using star polymer architectures with controlled anionic character

PubMed Central

Bagby, Taryn R.; Cai, Shuang; Duan, Shaofeng; Yang, Qiuhong; Thati, Sharadvi; Berkland, Cory; Aires, Daniel J.; Forrest, M. Laird

2015-01-01

Targeted lymphatic delivery of nanoparticles for drug delivery and imaging is primarily dependent on size and charge. Prior studies have observed increased lymphatic uptake and retentions of over 48 hrs for negatively charged particles compared to neutral and positively charged particles. We have developed new polymeric materials that extend retention over a more pharmaceutically relevant 7-day period. We used whole body fluorescence imaging to observe in mice the lymphatic trafficking of a series of anionic star poly-(6-O-methacryloyl-D-galactose) polymer-NIR dye (IR820) conjugates. The anionic charge of polymers was increased by modifying galactose moieties in the star polymers with succinic anhydride. Increasing anionic nature was associated with enhanced lymphatic uptake up to a zeta potential of ca. -40 mV; further negative charge did not affect lymphatic uptake. Compared to the 20% acid-conjugate, the 40 to 90% acid-star-polymer conjugates exhibited a 2.5- to 3.5-fold increase in lymphatic uptake in both the popliteal and iliac nodes. The polymer conjugates exhibited node half-lives of 2 to 20 hrs in the popliteal nodes and 19 to 114 hrs in the deeper iliac nodes. These polymer conjugates can deliver drugs or imaging agents with rapid lymphatic uptake and prolonged deep-nodal retention; thus they may provide a useful vehicle for sustained intralymphatic drug delivery with low toxicity. PMID:22546180

Effects of Alkylthio and Alkoxy Side Chains in Polymer Donor Materials for Organic Solar Cells.

PubMed

Cui, Chaohua; Wong, Wai-Yeung

2016-02-01

Side chains play a considerable role not only in improving the solubility of polymers for solution-processed device fabrication, but also in affecting the molecular packing, electron affinity and thus the device performance. In particular, electron-donating side chains show unique properties when employed to tune the electronic character of conjugated polymers in many cases. Therefore, rational electron-donating side chain engineering can improve the photovoltaic properties of the resulting polymer donors to some extent. Here, a survey of some representative examples which use electron-donating alkylthio and alkoxy side chains in conjugated organic polymers for polymer solar cell applications will be presented. It is envisioned that an analysis of the effect of such electron-donating side chains in polymer donors would contribute to a better understanding of this kind of side chain behavior in solution-processed conjugated organic polymers for polymer solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Process for crosslinking and extending conjugated diene-containing polymers

NASA Technical Reports Server (NTRS)

Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

1977-01-01

A process using a Diels-Alder reaction which increases the molecular weight and/or crosslinks polymers by reacting the polymers with bisunsaturated dienophiles is developed. The polymer comprises at least 75% by weight based on the reaction product, has a molecular weight of at least 5000 and a plurality of conjugated 1,3-diene systems incorporated into the molecular structure. A dienophile reaction with the conjugated 1,3-diene of the polymer is at least 1% by weight based on the reaction product. Examples of the polymer include polyesters, polyamides, polyethers, polysulfones and copolymers. The bisunsaturated dienophiles may include bis-maleimides, bis maleic and bis tumaric esters and amides. This method for expanding the molecular weight chains of the polymers, preferable thermoplastics, is advantageous for processing or fabricating thermoplastics. A low molecular weight thermoplastic is converted to a high molecular weight plastic having improved strength and toughness for use in the completed end use article.

Grafting density effects, optoelectrical properties and nano-patterning of poly(para-phenylene) brushes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Jihua; Alonzo, Jose; Yu, Xiang

2013-09-24

Well-defined conjugated polymers in confined geometries are challenging to synthesize and characterize, yet they are potentially useful in a broad range of organic optoelectronic devices such as transistors, light emitting diodes, solar cells, sensors, and nanocircuits. We report a systematic study of optoelectrical properties, grafting density effects, and nanopatterning of a model, end-tethered conjugated polymer system. Specifically, poly(para-phenylene) (PPP) brushes of various grafting density are created in situ by aromatizing well-defined, end-tethered poly(1,3-cyclohexadiene) (PCHD) “precursor brushes”. Furthermore, this novel precursor brush approach provides a convenient way to make and systematically control the grafting density of high molecular weight conjugated polymermore » brushes that would otherwise be insoluble. Finally, this allows us to examine how grafting density impacts the effective conjugation length of the conjugated PPP brushes and to adapt the fabrication method to develop spatially patterned conjugated brush systems, which is important for practical applications of conjugated polymer brushes.« less

Time-resolved energy transfer in DNA sequence detection using water-soluble conjugated polymers: the role of electrostatic and hydrophobic interactions.

PubMed

Xu, Qing-Hua; Gaylord, Brent S; Wang, Shu; Bazan, Guillermo C; Moses, Daniel; Heeger, Alan J

2004-08-10

We have investigated the energy transfer processes in DNA sequence detection by using cationic conjugated polymers and peptide nucleic acid (PNA) probes with ultrafast pump-dump-emission spectroscopy. Pump-dump-emission spectroscopy provides femtosecond temporal resolution and high sensitivity and avoids interference from the solvent response. The energy transfer from donor (the conjugated polymer) to acceptor (a fluorescent molecule attached to a PNA terminus) has been time resolved. The results indicate that both electrostatic and hydrophobic interactions contribute to the formation of cationic conjugated polymers/PNA-C/DNA complexes. The two interactions result in two different binding conformations. This picture is supported by the average donor-acceptor separations as estimated from time-resolved and steady-state measurements. Electrostatic interactions dominate at low concentrations and in mixed solvents.

Time-resolved energy transfer in DNA sequence detection using water-soluble conjugated polymers: The role of electrostatic and hydrophobic interactions

PubMed Central

Xu, Qing-Hua; Gaylord, Brent S.; Wang, Shu; Bazan, Guillermo C.; Moses, Daniel; Heeger, Alan J.

2004-01-01

We have investigated the energy transfer processes in DNA sequence detection by using cationic conjugated polymers and peptide nucleic acid (PNA) probes with ultrafast pump-dump-emission spectroscopy. Pump-dump-emission spectroscopy provides femtosecond temporal resolution and high sensitivity and avoids interference from the solvent response. The energy transfer from donor (the conjugated polymer) to acceptor (a fluorescent molecule attached to a PNA terminus) has been time resolved. The results indicate that both electrostatic and hydrophobic interactions contribute to the formation of cationic conjugated polymers/PNA-C/DNA complexes. The two interactions result in two different binding conformations. This picture is supported by the average donor–acceptor separations as estimated from time-resolved and steady-state measurements. Electrostatic interactions dominate at low concentrations and in mixed solvents. PMID:15282375

Energy transfer in PPV-based conjugated polymers: a defocused widefield fluorescence microscopy study.

PubMed

Hooley, E N; Tilley, A J; White, J M; Ghiggino, K P; Bell, T D M

2014-04-21

Both pendant and main chain conjugated MEH-PPV based polymers have been studied at the level of single chains using confocal and widefield fluorescence microscopy techniques. In particular, defocused widefield fluorescence is applied to reveal the extent of energy transfer in these polymers by identifying whether they act as single emitters. For main chain conjugated MEH-PPV, molecular weight and the surrounding matrix play a primary role in determining energy transport processes and whether single emitter behaviour is observed. Surprisingly in polymers with a saturated backbone but containing the same pendant MEH-PPV oligomer on each repeating unit, intra-chain energy transfer to a single emitter is also apparent. The results imply there is chromophore heterogeneity that can facilitate energy funneling to the emitting site. Both main chain conjugated and pendant MEH-PPV polymers exhibit changes in orientation of the emission dipole during a fluorescence trajectory of many seconds, whereas a model MEH-PPV oligomer does not. The results suggest that, in the polymers, the nature of the emitting chromophores can change during the time trajectory.

Improving the in vivo therapeutic index of siRNA polymer conjugates through increasing pH responsiveness.

PubMed

Guidry, Erin N; Farand, Julie; Soheili, Arash; Parish, Craig A; Kevin, Nancy J; Pipik, Brenda; Calati, Kathleen B; Ikemoto, Nori; Waldman, Jacob H; Latham, Andrew H; Howell, Bonnie J; Leone, Anthony; Garbaccio, Robert M; Barrett, Stephanie E; Parmar, Rubina Giare; Truong, Quang T; Mao, Bing; Davies, Ian W; Colletti, Steven L; Sepp-Lorenzino, Laura

2014-02-19

Polymer based carriers that aid in endosomal escape have proven to be efficacious siRNA delivery agents in vitro and in vivo; however, most suffer from cytotoxicity due in part to a lack of selectivity for endosomal versus cell membrane lysis. For polymer based carriers to move beyond the laboratory and into the clinic, it is critical to find carriers that are not only efficacious, but also have margins that are clinically relevant. In this paper we report three distinct categories of polymer conjugates that improve the selectivity of endosomal membrane lysis by relying on the change in pH associated with endosomal trafficking, including incorporation of low pKa heterocycles, acid cleavable amino side chains, or carboxylic acid pH sensitive charge switches. Additionally, we determine the therapeutic index of our polymer conjugates in vivo and demonstrate that the incorporation of pH responsive elements dramatically expands the therapeutic index to 10-15, beyond that of the therapeutic index (less than 3), for polymer conjugates previously reported.

Conformational Order in Aggregates of Conjugated Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jackson, Nicholas E.; Kohlstedt, Kevin L.; Savoie, Brett M.

With the abundant variety and increasing chemical complexity of conjugated poly-friers proliferating the field of organic semiconductors, it has become increasingly important to correlate the polymer molecular structure with its mesoscale conformational and morphological attributes. For instance, it is unknown which combinations of chemical moieties and periodicities predictably produce mesoscale ordering. Interestingly) not all ordered morphologies result in efficient devices. In this work we have parametrized accurate classical force-fields and used these to compute the conformational and aggregation characteristics of single strands of common conjugated polymers. Molecular dynamics trajectories are shown to reproduce experimentally observed polymeric ordering, concluding that efficientmore » organic photovoltaic devices span a range of polymer conformational classes, and suggesting that the solution-phase morphologies have far-reaching effects. Encouragingly, these simulations indicate that despite the wide-range of conformational classes present in successful devices, local molecular ordering, and not long-range crystallinity, appears to be the necessary requirement for efficient devices. Finally, we examine what makes a "good" solvent for conjugated polymers, concluding that dispersive pi-electron solvent-polymer interactions, and not the electrostatic potential of the backbone interacting with the solvent, are what primarily determine a polymer's solubility in a particular solvent, and consequently its morphological characteristics.« less

Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor-Acceptor Conjugated Polymers.

PubMed

Ayzner, Alexander L; Mei, Jianguo; Appleton, Anthony; DeLongchamp, Dean; Nardes, Alexandre; Benight, Stephanie; Kopidakis, Nikos; Toney, Michael F; Bao, Zhenan

2015-12-30

Conjugated polymers are widely used materials in organic photovoltaic devices. Owing to their extended electronic wave functions, they often form semicrystalline thin films. In this work, we aim to understand whether distribution of crystallographic orientations affects exciton diffusion using a low-band-gap polymer backbone motif that is representative of the donor/acceptor copolymer class. Using the fact that the polymer side chain can tune the dominant crystallographic orientation in the thin film, we have measured the quenching of polymer photoluminescence, and thus the extent of exciton dissociation, as a function of crystal orientation with respect to a quenching substrate. We find that the crystallite orientation distribution has little effect on the average exciton diffusion length. We suggest several possibilities for the lack of correlation between crystallographic texture and exciton transport in semicrystalline conjugated polymer films.

Exciton transport in π-conjugated polymers with conjugation defects.

PubMed

Meng, Ruixuan; Li, Yuan; Li, Chong; Gao, Kun; Yin, Sun; Wang, Luxia

2017-09-20

In π-conjugated polymers for photovoltaic applications, intrinsic conjugation defects are known to play crucial roles in impacting exciton transport after photoexcitation. However, the understanding of the associated microscopic processes still remains limited. Here, we present a theoretical investigation of the effects of different conjugation defects on the dynamics of exciton transport in two linearly coupled poly(p-phenylene vinylene) (PPV) molecules. The model system is constructed by employing an extended version of the Su-Schrieffer-Heeger model and the exciton behaviors are simulated by means of a quantum nonadiabatic dynamics. We identify two types of conjugation defects, i.e., weakening conjugation and strengthening conjugation, which are demonstrated to play different roles in impacting the dynamics of exciton transport in the system. The weakening conjugation acts as an energy well inclined to trap a moving exciton, while the strengthening conjugation acts as an energy barrier inclined to block the exciton. We also systematically simulate both intrachain and interchain dynamics of exciton transport, and find that an exciton could experience a "short-time delaying", "trapping", "blocking", or "hopping" process, which is determined by the defect type, strength, and position. These findings provide a microscopic understanding of how the exciton transport dynamics can be impacted by conjugation defects in an actual polymer system.

The optical and electrical properties of graphene oxide with water-soluble conjugated polymer composites by radiation.

PubMed

Jungo, Seung Tae; Oh, Seung-Hwan; Kim, Hyun Bin; Jeun, Joon-Pyo; Lee, Bum-Jae; Kang, Phil-Hyun

2013-11-01

In order to overcome the difficulty of dispersion and low conductivity in composite containing graphene, graphene oxide (GO) has been used instead of neat graphene. And the GO treated by radiation, could give improved conductivity of the GO-containing polymer composite. In this study, fluorene based water-soluble conjugated polymer (WPF-6-oxy-F) was introduced in GO solution to investigate the change of optical and electrical properties through radiation process. UV-Vis absorption of irradiated WPF-6-oxy-F-GO composite was red shifted and I(D)/I(G) ratio of Raman spectra decreased. XPS analysis showed that C-N bonds was formed after the irradiation and confirmed the increased bonds between the GO and the water-soluble conjugated polymer matrix. From the AFM and XPS analysis, it was found that the water-soluble conjugated polymer matrix was stacked between the modified GO in the morphology of irradiated WPF-6-oxy-F-GO composite was increased after gamma ray irradiation up to 10(-2) S/cm.

Preparation and Structural Studies on Hybrid Core-Shell Nanoparticles Consisting of Silica Core and Conjugated Block Copolymer Shell Prepared by Surface-Initiated Polymerization

NASA Astrophysics Data System (ADS)

Chatterjee, Sourav; Karam, Tony; Rosu, Cornelia; Li, Xin; Do, Changwoo; Youm, Sang Gil; Haber, Louis; Russo, Paul; Nesterov, Evgueni

Controlled Kumada catalyst-transfer polymerization occurring by chain-growth mechanism was developed for the synthesis of conjugated polymers and block copolymers from the surface of inorganic substrates such as silica nanoparticles. Although synthesis of conjugated polymers via Kumada polymerization became an established method for solution polymerization, carrying out the same reaction in heterogeneous conditions to form monodisperse polymer chains still remains a challenge. We developed and described a simple and efficient approach to the preparation of surface-immobilized layer of catalytic Ni(II) initiator, and demonstrated using it to prepare polymers and block copolymers on silica nanoparticle. The structure of the resulting hybrid nanostructures was thoroughly studied using small-angle neutron and X-ray scattering, thermal analysis, and optical spectroscopy. The photoexcitation energy transfer processes in the conjugated polymer shell were studied via steady-state and time resolved transient absorption spectroscopy. This study uncovered important details of the energy transfer, which will be discussed in this presentation.

Electrical characterization of fluorinated benzothiadiazole based conjugated copolymer - a promising material for high-performance solar cells

NASA Astrophysics Data System (ADS)

Toušek, J.; Toušková, J.; Remeš, Z.; Chomutová, R.; Čermák, J.; Helgesen, M.; Carlé, J. E.; Krebs, F. C.

2015-12-01

Measurements of electrical conductivity, electron work function, carrier mobility of holes and the diffusion length of excitons were performed on samples of conjugated polymers relevant to polymer solar cells. A state of the art fluorinated benzothiadiazole based conjugated copolymer (PBDTTHD - DTBTff) was studied and benchmarked against the reference polymer poly-3-hexylthiophene (P3HT). We employed, respectively, four electrode conductivity measurements, Kelvin probe work function measurements, carrier mobility using charge extraction by linearly increasing voltage (CELIV) measurements and diffusion length determinaton using surface photovoltage measurements.

Surface functionalization of quantum dots with fine-structured pH-sensitive phospholipid polymer chains.

PubMed

Liu, Yihua; Inoue, Yuuki; Ishihara, Kazuhiko

2015-11-01

To add novel functionality to quantum dots (QDs), we synthesized water-soluble and pH-responsive block-type polymers by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were composed of cytocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer segments, which contain a small fraction of active ester groups and can be used to conjugate biologically active compounds to the polymer, and pH-responsive poly(2-(N,N-diethylamino) ethyl methacrylate (DEAEMA)) segments. One terminal of the polymer chain had a hydrophobic alkyl group that originated from the RAFT initiator. This hydrophobic group can bind to the hydrophobic layer on the QD surface. A fluorescent dye was conjugated to the polymer chains via the active ester group. The block-type polymers have an amphiphilic nature in aqueous medium. The polymers were thus easily bound to the QD surface upon evaporation of the solvent from a solution containing the block-type polymer and QDs, yielding QD/fluorescence dye-conjugated polymer hybrid nanoparticles. Fluorescence resonance energy transfer (FRET) between the QDs (donors) and the fluorescent dye molecules (acceptors) was used to obtain information on the conformational dynamics of the immobilized polymers. Higher FRET efficiency of the QD/fluorescent dye-conjugated polymer hybrid nanoparticles was observed at pH 7.4 as compared to pH 5.0 due to a stretching-shrinking conformational motion of the poly(DEAEMA) segments in response to changes in pH. We concluded that the block-type MPC polymer-modified nanoparticles could be used to evaluate the pH of cells via FRET fluorescence based on the cytocompatibility of the MPC polymer. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of Polymer Conjugation on Hybridization Thermodynamics of Oligonucleic Acids.

PubMed

Ghobadi, Ahmadreza F; Jayaraman, Arthi

2016-09-15

In this work, we perform coarse-grained (CG) and atomistic simulations to study the effects of polymer conjugation on hybridization/melting thermodynamics of oligonucleic acids (ONAs). We present coarse-grained Langevin molecular dynamics simulations (CG-NVT) to assess the effects of the polymer flexibility, length, and architecture on hybridization/melting of ONAs with different ONA duplex sequences, backbone chemistry, and duplex concentration. In these CG-NVT simulations, we use our recently developed CG model of ONAs in implicit solvent, and treat the conjugated polymer as a CG chain with purely repulsive Weeks-Chandler-Andersen interactions with all other species in the system. We find that 8-100-mer linear polymer conjugation destabilizes 8-mer ONA duplexes with weaker Watson-Crick hydrogen bonding (WC H-bonding) interactions at low duplex concentrations, while the same polymer conjugation has an insignificant impact on 8-mer ONA duplexes with stronger WC H-bonding. To ensure the configurational space is sampled properly in the CG-NVT simulations, we also perform CG well-tempered metadynamics simulations (CG-NVT-MetaD) and analyze the free energy landscape of ONA hybridization for a select few systems. We demonstrate that CG-NVT-MetaD simulation results are consistent with the CG-NVT simulations for the studied systems. To examine the limitations of coarse-graining in capturing ONA-polymer interactions, we perform atomistic parallel tempering metadynamics simulations at well-tempered ensemble (AA-MetaD) for a 4-mer DNA in explicit water with and without conjugation to 8-mer poly(ethylene glycol) (PEG). AA-MetaD simulations also show that, for a short DNA duplex at T = 300 K, a condition where the DNA duplex is unstable, conjugation with PEG further destabilizes DNA duplex. We conclude with a comparison of results from these three different types of simulations and discuss their limitations and strengths.

Patents -- Alan J. Heeger (1984 - 1994)

Science.gov Websites

to be doped is employed as one or both of the electrodes, and the electrolyte is a compound which is of novel lightweight secondary batteries which employ doped or dopable conjugated polymers as one or comprises at least one electrode having as an active materials a conjugated polymer, the polymer being doped

Water-Soluble Conjugated Polymers: Self-Assembly and Biosensor Applications

NASA Astrophysics Data System (ADS)

Bazan, Guillermo

2005-03-01

Homogeneous assays can be designed which take advantage of the optical amplification of conjugated polymers and the self-assembly characteristic of aqueous polyelectrolytes. For example, a ssDNA sequence sensor comprises an aqueous solution containing a cationic water soluble conjugated polymer such as poly(9,9-bis(trimethylammonium)-hexyl)-fluorene phenylene) with a peptide nucleic acid (PNA) labeled with a dye (PNA-C*). Signal transduction is controlled by hybridization of the neutral PNA-C* probe and the negative ssDNA target, resulting in favorable electrostatic interactions between the hybrid complex and the cationic polymer. Distance requirements for Förster energy transfer are thus met only when ssDNA of complementary sequence to the PNA-C* probe is present. Signal amplification by the conjugated polymer provides fluorescein emission >25 times higher than that of the directly excited dye. Transduction by electrostatic interactions followed by energy transfer is a general strategy. Examples involving other biomolecular recognition events, such as DNA/DNA, RNA/protein and RNA/RNA, will also be provided. The mechanism of biosensing will be discussed, with special attention to the varying contributions of hydrophobic and electrostatic forces, polymer conformation, charge density, local concentration of C*s and tailored defect sites for aggregation-induced optical changes. Finally, the water solubility of these conjugated polymers opens possibilities for spin casting onto organic materials, without dissolving the underlying layers. This property is useful for fabricating multilayer organic optoelectronic devices by simple solution techniques.

Beyond superquenching: Hyper-efficient energy transfer from conjugated polymers to gold nanoparticles

PubMed Central

Fan, Chunhai; Wang, Shu; Hong, Janice W.; Bazan, Guillermo C.; Plaxco, Kevin W.; Heeger, Alan J.

2003-01-01

Gold nanoparticles quench the fluorescence of cationic polyfluorene with Stern–Volmer constants (KSV) approaching 1011 M—1, several orders of magnitude larger than any previously reported conjugated polymer–quencher pair and 9–10 orders of magnitude larger than small molecule dye–quencher pairs. The dependence of KSV on ionic strength, charge and conjugation length of the polymer, and the dimensions (and thus optical properties) of the nanoparticles suggests that three factors account for this extraordinary efficiency: (i) amplification of the quenching via rapid internal energy or electron transfer, (ii) electrostatic interactions between the cationic polymer and anionic nanoparticles, and (iii) the ability of gold nanoparticles to quench via efficient energy transfer. As a result of this extraordinarily high KSV, quenching can be observed even at subpicomolar concentrations of nanoparticles, suggesting that the combination of conjugated polymers with these nanomaterials can potentially lead to improved sensitivity in optical biosensors. PMID:12750470

Hole Transfer from Low Band Gap Quantum Dots to Conjugated Polymers in Organic/Inorganic Hybrid Photovoltaics.

PubMed

Colbert, Adam E; Janke, Eric M; Hsieh, Stephen T; Subramaniyan, Selvam; Schlenker, Cody W; Jenekhe, Samson A; Ginger, David S

2013-01-17

We use photoinduced absorption (PIA) spectroscopy to investigate pathways for photocurrent generation in hybrid organic/inorganic quantum dot bulk heterojunction solar cells. We study blends of the conjugated polymer poly(2,3-bis(2-(hexyldecyl)quinoxaline-5,8-diyl-alt-N-(2-hexyldecyl)dithieno[3,2-b:2',3'-d]pyrrole) (PDTPQx-HD) with PbS quantum dots and find that positively charged polarons are formed on the conjugated polymer following selective photoexcitation of the PbS quantum dots. This result provides a direct spectroscopic fingerprint demonstrating that photoinduced hole transfer occurs from the photoexcited quantum dots to the host polymer. We compute the relative yields of long-lived holes following photoexcitation of both the polymer and quantum dot phases and estimate that more long-lived polarons are produced per photon absorbed by the polymer phase than by the quantum dot phase.

The Holy Grail of Polymer Therapeutics for Cancer Therapy: An Overview on the Pharmacokinetics and Bio Distribution.

PubMed

Dyawanapelly, Sathish; Junnuthula, Vijayabhaskar Reddy; Singh, AkhileshVikram

2015-01-01

In recent years, multifaceted clinical benefits of polymeric therapeutics have been reported. Over the past decades, cancer has been one of the leading causes of mortality in the world. Many clinically approved chemotherapeutics encounter potential challenges against deadly cancer. Moreover, safety and efficacy of anticancer agents have been limited by undesirable pharmacokinetics and biodistribution. To address these limitations, various polymer drug conjugates are being studied and developed to improve the antitumor efficacy. Among other therapeutics, polymer therapeutics are well established platforms that circumvent anticancer therapeutics from enzymatic metabolism via direct conjugation to therapeutic molecules. Interestingly, polymer therapeutics meets an unmet need of small molecules. Further clinical study showed that polymer-drug conjugation can achieve desired pharmacokinetics and biodistribution properties of several anticancer drugs. The present retrospective review mainly enlightens the most recent preclinical and clinical studies include safety, stability, pharmacokinetic behavior and distribution of polymer therapeutics.

Non-Traditional Aromatic Topologies and Biomimetic Assembly Motifs as Components of Functional Pi-Conjugated Oligomers

PubMed Central

Tovar, John D.; Diegelmann, Stephen R.; Peart, Patricia A.

2010-01-01

This article will highlight our recent work using conjugated oligomers as precursors to electroactive polymer films and self-assembling nanomaterials. One area of investigation has focused on nonbenzenoid aromaticity in the context of charge delocalization in conjugated polymers. In these studies, polymerizable pi-conjugated units were coupled onto unusual aromatic cores such as methano[10]annulene. This article will also show how biologically-inspired assembly of molecularly well-defined oligopeptides that flank pi-conjugated oligomers has resulted in the aqueous construction of 1-dimensional nanomaterials that encourage electronic delocalization among the pi-electron systems.

Crosslinked polymer nanoparticles containing single conjugated polymer chains

NASA Astrophysics Data System (ADS)

Ponzio, Rodrigo A.; Marcato, Yésica L.; Gómez, María L.; Waiman, Carolina V.; Chesta, Carlos A.; Palacios, Rodrigo E.

2017-06-01

Conjugated polymer nanoparticles are widely used in fluorescent labeling and sensing, as they have mean radii between 5 and 100 nm, narrow size dispersion, high brightness, and are photochemically stable, allowing single particle detection with high spatial and temporal resolution. Highly crosslinked polymers formed by linking individual chains through covalent bonds yield high-strength rigid materials capable of withstanding dissolution by organic solvents. Hence, the combination of crosslinked polymers and conjugated polymers in a nanoparticulated material presents the possibility of interesting applications that require the combined properties of constituent polymers and nanosized dimension. In the present work, F8BT@pEGDMA nanoparticles composed of poly(ethylene glycol dimethacrylate) (pEGDMA; a crosslinked polymer) and containing the commercial conjugated polymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) were synthesized and characterized. Microemulsion polymerization was applied to produce F8BT@pEDGMA particles with nanosized dimensions in a ∼25% yield. Photophysical and size distribution properties of F8BT@pEDGMA nanoparticles were evaluated by various methods, in particular single particle fluorescence microscopy techniques. The results demonstrate that the crosslinking/polymerization process imparts structural rigidity to the F8BT@pEDGMA particles by providing resistance against dissolution/disintegration in organic solvents. The synthesized fluorescent crosslinked nanoparticles contain (for the most part) single F8BT chains and can be detected at the single particle level, using fluorescence microscopy, which bodes well for their potential application as molecularly imprinted polymer fluorescent nanosensors with high spatial and temporal resolution.

All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Nanjia; Dudnik, Alexander S.; Li, Ting I. N. G.

2015-12-31

ABSTRACT: The influence of the number-average molecular weight (Mn) on the blend film morphology and photovoltaic performance of all-polymer solar cells (APSCs) fabricated with the donor polymer poly[5-(2-hexyldodecyl)-1,3-thieno[3,4- c]pyrrole-4,6-dione-alt-5,5-(2,5-bis(3-dodecylthiophen-2-yl)- thiophene)] (PTPD3T) and acceptor polymer poly{[N,N'- bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)- 2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2); N2200) is systematically investigated. The M n effect analysis of both PTPD3T and N2200 is enabled by implementing a polymerization strategy which produces conjugated polymers with tunable M ns. Experimental and coarse-grain modeling results reveal that systematic M n variation greatly influences both intrachain and interchain interactions and ultimately the degree of phase separation and morphology evolution. Specifically, increasing M n formore » both polymers shrinks blend film domain sizes and enhances donor-acceptor polymer-polymer interfacial areas, affording increased short-circuit current densities (J sc). However, the greater disorder and intermixed feature proliferation accompanying increasing M n promotes charge carrier recombination, reducing cell fill factors (FF). The optimized photoactive layers exhibit well-balanced exciton dissociation and charge transport characteristics, ultimately providing solar cells with a 2-fold PCE enhancement versus devices with nonoptimal M ns. Overall, it is shown that proper and precise tuning of both donor and acceptor polymer M ns is critical for optimizing APSC performance. In contrast to reports where maximum power conversion efficiencies (PCEs) are achieved for the highest M ns, the present two-dimensional M n optimization matrix strategy locates a PCE “sweet spot” at intermediate Mns of both donor and acceptor polymers. This study provides synthetic methodologies to predictably access conjugated polymers with desired M n and highlights the importance of optimizing M n for both polymer components to realize the full potential of APSC performance.« less

Dendritic polymer-based nanodevices for targeted drug delivery applications

NASA Astrophysics Data System (ADS)

Kannan, R. M.; Kolhe, Parag; Gurdag, Sezen; Khandare, Jayant; Lieh-Lai, Mary

2004-03-01

Dendrimers and hyperbranched polymers are unimolecular micellar nanostructures, characterized by globular shape ( ˜ 20 nm) and large density of functional groups at periphery. The tailorable end groups make them ideal for conjugation with drugs, ligands, and imagining agents, making them an attractive molecular nanodevices for drug delivery. Compared to linear polymers and nanoparticles, these nanodevices enter cells rapidly, carrying drugs and delivering them inside cells. Performance of nanodevices prepared for asthma and cancer drug delivery will be discussed. Our conjugation procedure produced very high drug payloads. Dendritic polymer-drug conjugates were very effective in transporting methotrexate (a chemotherapy drug) into both sensitive (CCRF-CEM cell line) and resistant cell line (CEM-MTX). The conjugate nanodevice was 3 times more effective than free drug in the sensitive line, and 9 times more effective in the resistant cell line (based on IC50). The physics of cell entry and drug release from these nanodevices are being investigated. The conjugates appear to enter cells through endocytosis, with the rate of entry dependent on end-group, molecular weight, the pH of the medium, and the cancerous nature of the cells.

Folate receptor‐targeted aminoglycoside‐derived polymers for transgene expression in cancer cells

PubMed Central

Godeshala, Sudhakar; Nitiyanandan, Rajeshwar; Thompson, Brian; Goklany, Sheba; Nielsen, David R.

2016-01-01

Abstract Targeted delivery of anticancer therapeutics can potentially overcome the limitations associated with current chemotherapeutic regimens. Folate receptors are overexpressed in several cancers, including ovarian, triple‐negative breast and bladder cancers, making them attractive for targeted delivery of nucleic acid therapeutics to these tumors. This work describes the synthesis, characterization and evaluation of folic acid‐conjugated, aminoglycoside‐derived polymers for targeted delivery of transgenes to breast and bladder cancer cell lines. Transgene expression was significantly higher with FA‐conjugated aminoglycoside‐derived polymers than with Lipofectamine, and these polymers demonstrated minimal cytotoxicty. Competitive inhibition using free folic acid significantly reduced transgene expression efficacy of folate‐targeted polymers, suggesting a role for folate receptor‐mediated uptake. High efficacy FA‐targeted polymers were employed to deliver a plasmid expressing the TRAIL protein, which induced death in cancer cells. These results indicate that FA‐conjugated aminoglycoside‐derived polymers are promising for targeted delivery of nucleic acids to cancer cells that overexpress folate receptors. PMID:29313013

11.4% Efficiency non-fullerene polymer solar cells with trialkylsilyl substituted 2D-conjugated polymer as donor

PubMed Central

Bin, Haijun; Gao, Liang; Zhang, Zhi-Guo; Yang, Yankang; Zhang, Yindong; Zhang, Chunfeng; Chen, Shanshan; Xue, Lingwei; Yang, Changduk; Xiao, Min; Li, Yongfang

2016-01-01

Simutaneously high open circuit voltage and high short circuit current density is a big challenge for achieving high efficiency polymer solar cells due to the excitonic nature of organic semdonductors. Herein, we developed a trialkylsilyl substituted 2D-conjugated polymer with the highest occupied molecular orbital level down-shifted by Si–C bond interaction. The polymer solar cells obtained by pairing this polymer with a non-fullerene acceptor demonstrated a high power conversion efficiency of 11.41% with both high open circuit voltage of 0.94 V and high short circuit current density of 17.32 mA cm−2 benefitted from the complementary absorption of the donor and acceptor, and the high hole transfer efficiency from acceptor to donor although the highest occupied molecular orbital level difference between the donor and acceptor is only 0.11 eV. The results indicate that the alkylsilyl substitution is an effective way in designing high performance conjugated polymer photovoltaic materials. PMID:27905397

11.4% Efficiency non-fullerene polymer solar cells with trialkylsilyl substituted 2D-conjugated polymer as donor.

PubMed

Bin, Haijun; Gao, Liang; Zhang, Zhi-Guo; Yang, Yankang; Zhang, Yindong; Zhang, Chunfeng; Chen, Shanshan; Xue, Lingwei; Yang, Changduk; Xiao, Min; Li, Yongfang

2016-12-01

Simutaneously high open circuit voltage and high short circuit current density is a big challenge for achieving high efficiency polymer solar cells due to the excitonic nature of organic semdonductors. Herein, we developed a trialkylsilyl substituted 2D-conjugated polymer with the highest occupied molecular orbital level down-shifted by Si-C bond interaction. The polymer solar cells obtained by pairing this polymer with a non-fullerene acceptor demonstrated a high power conversion efficiency of 11.41% with both high open circuit voltage of 0.94 V and high short circuit current density of 17.32 mA cm -2 benefitted from the complementary absorption of the donor and acceptor, and the high hole transfer efficiency from acceptor to donor although the highest occupied molecular orbital level difference between the donor and acceptor is only 0.11 eV. The results indicate that the alkylsilyl substitution is an effective way in designing high performance conjugated polymer photovoltaic materials.

Synthesis and study of conjugated polymers containing Di- or Triphenylamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sukwattanasinitt, M.

1996-06-21

This thesis consists of two separate parts. The first part addresses the synthesis and study of conjugated polymers containing di- or triphenylamine. Two types of polymers: linear polymers and dendrimers, were synthesized. The polymers were characterized by NMR, IR, UV, GPC, TGA and DSC. Electronic and optical properties of the polymers were studied through the conductivity measurements and excitation- emission spectra. the second part of this thesis deals with a reaction of electron-rich acetylenes with TCNE. The discovery of the reaction from charge transfer complex studies and the investigation of this reaction on various electron-rich acetylenes are presented.

Method to create gradient index in a polymer

DOEpatents

Dirk, Shawn M; Johnson, Ross Stefan; Boye, Robert; Descour, Michael R; Sweatt, William C; Wheeler, David R; Kaehr, Bryan James

2014-10-14

Novel photo-writable and thermally switchable polymeric materials exhibit a refractive index change of .DELTA.n.gtoreq.1.0 when exposed to UV light or heat. For example, lithography can be used to convert a non-conjugated precursor polymer to a conjugated polymer having a higher index-of-refraction. Further, two-photon lithography can be used to pattern high-spatial frequency structures.

Gemcitabine-based polymer-drug conjugate for enhanced anticancer effect in colon cancer.

PubMed

Liang, Tie-Jun; Zhou, Zhong-Mei; Cao, Ying-Qing; Ma, Ming-Ze; Wang, Xiao-Jun; Jing, Kai

2016-11-20

In this study, we have demonstrated gemcitabine (GEM)-conjugated amphiphilic biodegradable polymeric drug carriers. Our aim was to increase the chemotherapeutic potential of GEM in colon cancer by forming a unique polymer-drug conjugates. The polymer-drug conjugate micelles were nanosized with a typical spherical shape. The GEM-conjugated methoxy poly(ethylene glycol)-poly(lactic acid) (GEM-PL) exhibited a controlled release of drug in both the pH conditions. The developed GEM-PL efficiently killed the HT29 cancers cells in a typical time dependent manner. The clonogenic assay further confirmed the superior anticancer effect of GEM-PL which showed least number of colonies. GEM-PL formulation exhibited a significantly higher apoptosis of cancer cells (∼25%) when stained using Annexin-V/PI kit. Conjugation of GEM to the mPEG-PLA significantly enhanced the blood circulation potential in animal model compared to that of free GEM. GEM-PL could prevent quick elimination of the drug and can provide sufficient time for the greater accumulation of GEM at the tumor sites. GEM-PL showed a remarkable tumor regression effect as evident from the lowest tumor volume in HT-29 containing tumor model. Overall, mPEG-PLA/GEM conjugates showed the potential of polymer-based drug targeting and might hold significant clinical potential in the treatment of colon cancers. Copyright © 2016 Elsevier B.V. All rights reserved.

Exploring the origin of high optical absorption in conjugated polymers.

PubMed

Vezie, Michelle S; Few, Sheridan; Meager, Iain; Pieridou, Galatia; Dörling, Bernhard; Ashraf, Raja Shahid; Goñi, Alejandro R; Bronstein, Hugo; McCulloch, Iain; Hayes, Sophia C; Campoy-Quiles, Mariano; Nelson, Jenny

2016-07-01

The specific optical absorption of an organic semiconductor is critical to the performance of organic optoelectronic devices. For example, higher light-harvesting efficiency can lead to higher photocurrent in solar cells that are limited by sub-optimal electrical transport. Here, we compare over 40 conjugated polymers, and find that many different chemical structures share an apparent maximum in their extinction coefficients. However, a diketopyrrolopyrrole-thienothiophene copolymer shows remarkably high optical absorption at relatively low photon energies. By investigating its backbone structure and conformation with measurements and quantum chemical calculations, we find that the high optical absorption can be explained by the high persistence length of the polymer. Accordingly, we demonstrate high absorption in other polymers with high theoretical persistence length. Visible light harvesting may be enhanced in other conjugated polymers through judicious design of the structure.

Unusual Internal Electron Transfer in Conjugated Radical Polymers.

PubMed

Li, Fei; Gore, Danielle N; Wang, Shaoyang; Lutkenhaus, Jodie L

2017-08-07

Nitroxide-containing organic radical polymers (ORPs) have captured attention for their high power and fast redox kinetics. Yet a major challenge is the polymer's aliphatic backbone, resulting in a low electronic conductivity. Recent attempts that replace the aliphatic backbone with a conjugated one have not met with success. The reason for this is not understood until now. We examine a family of polythiophenes bearing nitroxide radical groups, showing that while both species are electrochemically active, there exists an internal electron transfer mechanism that interferes with stabilization of the polymer's fully oxidized form. This finding directs the future design of conjugated radical polymers in energy storage and electronics, where careful attention to the redox potential of the backbone relative to the organic radical species is needed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Compositions for directed alignment of conjugated polymers

DOEpatents

Kim, Jinsang; Kim, Bong-Gi; Jeong, Eun Jeong

2016-04-19

Conjugated polymers (CPs) achieve directed alignment along an applied flow field and a dichroic ratio of as high as 16.67 in emission from well-aligned thin films and fully realized anisotropic optoelectronic properties of CPs in field-effect transistor (FET).

Diazobenzene-containing conjugated polymers as dark quenchers.

PubMed

Wu, Jiatao; Tan, Ying; Xie, Yonghua; Wu, Yi; Zhao, Rui; Jiang, Yuyang; Tan, Chunyan

2013-12-18

The synthesis and photophysical characterization of new conjugated polymers (CPs) with alternating phenylethynylene and diazobenzene (azo-PPE) units were reported, which showed broadened absorption and no measurable fluorescence. Quenching studies showed that azo-PPEs displayed high efficiency over a wide wavelength range.

Thermoreversible Morphology and Conductivity of a Conjugated Polymer Network Embedded in Block Copolymer Self-Assemblies

DOE PAGES

Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe; ...

2016-07-19

Self-assembly of block copolymers provides numerous opportunities to create functional materials, utilizing self-assembled microdomains with a variety of morphology and periodic architectures as templates for functional nanofillers. Here new progress is reported toward the fabrication of thermally responsive and electrically conductive polymeric self-assemblies made from a water-soluble poly(thiophene) derivative with short poly(ethylene oxide) side chains and Pluronic L62 block copolymer solution in water. The structural and electrical properties of conjugated polymer-embedded self-assembled architectures are investigated by combining small-angle neutron and X-ray scattering, coarse-grained molecular dynamics simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporatingmore » them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellarto- lamellar phase transition defines the embedded conjugated polymer network. As a result, the conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. In conclusion, this study shows promise for enabling more flexibility in processing and utilizing water-soluble conjugated polymers in aqueous solutions for self-assembly based fabrication of stimuli-responsive nanostructures and sensory materials.« less

Thermoreversible Morphology and Conductivity of a Conjugated Polymer Network Embedded in Block Copolymer Self-Assemblies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe

Self-assembly of block copolymers provides numerous opportunities to create functional materials, utilizing self-assembled microdomains with a variety of morphology and periodic architectures as templates for functional nanofillers. Here new progress is reported toward the fabrication of thermally responsive and electrically conductive polymeric self-assemblies made from a water-soluble poly(thiophene) derivative with short poly(ethylene oxide) side chains and Pluronic L62 block copolymer solution in water. The structural and electrical properties of conjugated polymer-embedded self-assembled architectures are investigated by combining small-angle neutron and X-ray scattering, coarse-grained molecular dynamics simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporatingmore » them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellarto- lamellar phase transition defines the embedded conjugated polymer network. As a result, the conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. In conclusion, this study shows promise for enabling more flexibility in processing and utilizing water-soluble conjugated polymers in aqueous solutions for self-assembly based fabrication of stimuli-responsive nanostructures and sensory materials.« less

Stimulation of immune systems by conjugated polymers and their potential as an alternative vaccine adjuvant.

PubMed

Gong, Hua; Xiang, Jian; Xu, Ligeng; Song, Xuejiao; Dong, Ziliang; Peng, Rui; Liu, Zhuang

2015-12-07

Recently, conjugated polymers have been widely explored in the field of nanomedicine. Careful evaluations of their biological effects are thus urgently needed. Hereby, we systematically evaluated the biological effects of different types of conjugated polymers on macrophages and dendritic cells (DCs), which play critical roles in the innate and adaptive immune systems, respectively. While naked poly-(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) ( PSS) exhibits a high level of cytotoxicity, polyethylene glycol (PEG) modified PSS (PEDOT:PSS-PEG) shows greatly reduced toxicity to various types of cells. To our surprise, PEGylation of PSS could obviously enhance the cellular uptake of these nanoparticles, leading to subsequent immune stimulations of both macrophages and DCs. In contrast, another type of conjugated polymer, polypyrrole (PPy), is found to be an inert material with neither significant cytotoxicity nor noticeable immune-stimulation activity. Interestingly, utilizing ovalbumin (OVA) as a model antigen, it is further uncovered in our ex vivo experiment that PSS-PEG may serve as an adjuvant to greatly enhance the immunogenicity of OVA upon simple mixing. Our study on the one hand suggests the promise of developing novel nano-adjuvants based on conjugated polymers, and on the other hand highlights the importance of careful evaluations of the impacts of any new nanomaterials developed for nanomedicine on the immune systems.

Stimulation of immune systems by conjugated polymers and their potential as an alternative vaccine adjuvant

NASA Astrophysics Data System (ADS)

Gong, Hua; Xiang, Jian; Xu, Ligeng; Song, Xuejiao; Dong, Ziliang; Peng, Rui; Liu, Zhuang

2015-11-01

Recently, conjugated polymers have been widely explored in the field of nanomedicine. Careful evaluations of their biological effects are thus urgently needed. Hereby, we systematically evaluated the biological effects of different types of conjugated polymers on macrophages and dendritic cells (DCs), which play critical roles in the innate and adaptive immune systems, respectively. While naked poly-(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) exhibits a high level of cytotoxicity, polyethylene glycol (PEG) modified PEDOT:PSS (PEDOT:PSS-PEG) shows greatly reduced toxicity to various types of cells. To our surprise, PEGylation of PEDOT:PSS could obviously enhance the cellular uptake of these nanoparticles, leading to subsequent immune stimulations of both macrophages and DCs. In contrast, another type of conjugated polymer, polypyrrole (PPy), is found to be an inert material with neither significant cytotoxicity nor noticeable immune-stimulation activity. Interestingly, utilizing ovalbumin (OVA) as a model antigen, it is further uncovered in our ex vivo experiment that PEDOT:PSS-PEG may serve as an adjuvant to greatly enhance the immunogenicity of OVA upon simple mixing. Our study on the one hand suggests the promise of developing novel nano-adjuvants based on conjugated polymers, and on the other hand highlights the importance of careful evaluations of the impacts of any new nanomaterials developed for nanomedicine on the immune systems.Recently, conjugated polymers have been widely explored in the field of nanomedicine. Careful evaluations of their biological effects are thus urgently needed. Hereby, we systematically evaluated the biological effects of different types of conjugated polymers on macrophages and dendritic cells (DCs), which play critical roles in the innate and adaptive immune systems, respectively. While naked poly-(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) exhibits a high level of cytotoxicity, polyethylene glycol (PEG) modified PEDOT:PSS (PEDOT:PSS-PEG) shows greatly reduced toxicity to various types of cells. To our surprise, PEGylation of PEDOT:PSS could obviously enhance the cellular uptake of these nanoparticles, leading to subsequent immune stimulations of both macrophages and DCs. In contrast, another type of conjugated polymer, polypyrrole (PPy), is found to be an inert material with neither significant cytotoxicity nor noticeable immune-stimulation activity. Interestingly, utilizing ovalbumin (OVA) as a model antigen, it is further uncovered in our ex vivo experiment that PEDOT:PSS-PEG may serve as an adjuvant to greatly enhance the immunogenicity of OVA upon simple mixing. Our study on the one hand suggests the promise of developing novel nano-adjuvants based on conjugated polymers, and on the other hand highlights the importance of careful evaluations of the impacts of any new nanomaterials developed for nanomedicine on the immune systems. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06081h

Conjugated polymer energy level shifts in lithium-ion battery electrolytes.

PubMed

Song, Charles Kiseok; Eckstein, Brian J; Tam, Teck Lip Dexter; Trahey, Lynn; Marks, Tobin J

2014-11-12

The ionization potentials (IPs) and electron affinities (EAs) of widely used conjugated polymers are evaluated by cyclic voltammetry (CV) in conventional electrochemical and lithium-ion battery media, and also by ultraviolet photoelectron spectroscopy (UPS) in vacuo. By comparing the data obtained in the different systems, it is found that the IPs of the conjugated polymer films determined by conventional CV (IPC) can be correlated with UPS-measured HOMO energy levels (EH,UPS) by the relationship EH,UPS = (1.14 ± 0.23) × qIPC + (4.62 ± 0.10) eV, where q is the electron charge. It is also found that the EAs of the conjugated polymer films measured via CV in conventional (EAC) and Li(+) battery (EAB) media can be linearly correlated by the relationship EAB = (1.07 ± 0.13) × EAC + (2.84 ± 0.22) V. The slopes and intercepts of these equations can be correlated with the dielectric constants of the polymer film environments and the redox potentials of the reference electrodes, as modified by the surrounding electrolyte, respectively.

DNA detection using water-soluble conjugated polymers and peptide nucleic acid probes

PubMed Central

Gaylord, Brent S.; Heeger, Alan J.; Bazan, Guillermo C.

2002-01-01

The light-harvesting properties of cationic conjugated polymers are used to sensitize the emission of a dye on a specific peptide nucleic acid (PNA) sequence for the purpose of homogeneous, “real-time” DNA detection. Signal transduction is controlled by hybridization of the neutral PNA probe and the negative DNA target. Electrostatic interactions bring the hybrid complex and cationic polymer within distances required for Förster energy transfer. Conjugated polymer excitation provides fluorescein emission >25 times higher than that obtained by exciting the dye, allowing detection of target DNA at concentrations of 10 pM with a standard fluorometer. A simple and highly sensitive assay with optical amplification that uses the improved hybridization behavior of PNA/DNA complexes is thus demonstrated. PMID:12167673

Two-step polymer- and liposome-enzyme prodrug therapies for cancer: PDEPT and PELT concepts and future perspectives.

PubMed

Scomparin, Anna; Florindo, Helena F; Tiram, Galia; Ferguson, Elaine L; Satchi-Fainaro, Ronit

2017-09-01

Polymer-directed enzyme prodrug therapy (PDEPT) and polymer enzyme liposome therapy (PELT) are two-step therapies developed to provide anticancer drugs site-selective intratumoral accumulation and release. Nanomedicines, such as polymer-drug conjugates and liposomal drugs, accumulate in the tumor site due to extravasation-dependent mechanism (enhanced permeability and retention - EPR - effect), and further need to cross the cellular membrane and release their payload in the intracellular compartment. The subsequent administration of a polymer-enzyme conjugate able to accumulate in the tumor tissue and to trigger the extracellular release of the active drug showed promising preclinical results. The development of polymer-enzyme, polymer-drug conjugates and liposomal drugs had undergone a vast advancement over the past decades. Several examples of enzyme mimics for in vivo therapy can be found in the literature. Moreover, polymer therapeutics often present an enzyme-sensitive mechanism of drug release. These nanomedicines can thus be optimal substrates for PDEPT and this review aims to provide new insights and stimuli toward the future perspectives of this promising combination. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced photophysics of conjugated polymers

DOEpatents

Chen, Liaohai [Darien, IL

2007-06-12

A particulate fluorescent conjugated polymer surfactant complex and method of making and using same. The particles are between about 15 and about 50 nm and when formed from a lipsome surfactant have a charge density similar to DNA and are strongly absorbed by cancer cells.

Effects of doping and interchain interactions on the metal-insulator transition in trans-polyacetylene

NASA Astrophysics Data System (ADS)

Paulsson, Magnus; Stafström, Sven

1999-09-01

Using a tight-binding Hamiltonian the metal-insulator phase diagram for trans-polyacetylene was calculated as a function of doping concentration and interchain interaction strength. The phase boundary for the periodic system coincides with the gap closing, which occurs for certain combinations of critical values for the doping concentration and the interchain interaction strength. The values found are in good agreement with the experimentally observed increase in the Pauli susceptibility. To simulate disorder in the polymer, the effect of finite chain lengths was studied. This type of disorder pushes the metal/insulator phase boundary towards the metallic side of the phase diagram. An increase in the doping concentration and/or interchain interaction is shown to reduce the localizing effects of disorder effectively. For realistic values of the interchain interaction strength the number of chain breaks needed to localize the states at the Fermi energy is quite small, of the order of a few percent. The localization length is found to be substantially longer than the conjugation length of the polymer.

Understanding morphology-mobility dependence in PEDOT:Tos

NASA Astrophysics Data System (ADS)

Rolland, Nicolas; Franco-Gonzalez, Juan Felipe; Volpi, Riccardo; Linares, Mathieu; Zozoulenko, Igor V.

2018-04-01

The potential of conjugated polymers to compete with inorganic materials in the field of semiconductor is conditional on fine-tuning of the charge carriers mobility. The latter is closely related to the material morphology, and various studies have shown that the bottleneck for charge transport is the connectivity between well-ordered crystallites, with a high degree of π -π stacking, dispersed into a disordered matrix. However, at this time there is a lack of theoretical descriptions accounting for this link between morphology and mobility, hindering the development of systematic material designs. Here we propose a computational model to predict charge carriers mobility in conducting polymer PEDOT depending on the physicochemical properties of the system. We start by calculating the morphology using molecular dynamics simulations. Based on the calculated morphology we perform quantum mechanical calculation of the transfer integrals between states in polymer chains and calculate corresponding hopping rates using the Miller-Abrahams formalism. We then construct a transport resistive network, calculate the mobility using a mean-field approach, and analyze the calculated mobility in terms of transfer integrals distributions and percolation thresholds. Our results provide theoretical support for the recent study [Noriega et al., Nat. Mater. 12, 1038 (2013), 10.1038/nmat3722] explaining why the mobility in polymers rapidly increases as the chain length is increased and then saturates for sufficiently long chains. Our study also provides the answer to the long-standing question whether the enhancement of the crystallinity is the key to designing high-mobility polymers. We demonstrate, that it is the effective π -π stacking, not the long-range order that is essential for the material design for the enhanced electrical performance. This generic model can compare the mobility of a polymer thin film with different solvent contents, solvent additives, dopant species or polymer characteristics, providing a general framework to design new high mobility conjugated polymer materials.

Chromophores in phenylenevinylene-based conjugated polymers: role of conformational kinks and chemical defects.

PubMed

Hennebicq, Emmanuelle; Deleener, Caroline; Brédas, Jean-Luc; Scholes, Gregory D; Beljonne, David

2006-08-07

The influence of chemical defects and conformational kinks on the nature of the lowest electronic excitations in phenylenevinylene-based polymers is assessed at the semiempirical quantum-chemical level. The amount of excited-state localization and the amplitude of through-space (Coulomb-like) versus through-bond (charge-transfer-like) interactions have been quantified by comparing the results provided by excitonic and supermolecular models. While excitation delocalization among conjugated segments delineated by the defects occurs in the acceptor configuration, self-confinement on individual chromophores follows from geometric relaxation in the excited-state donor configuration. The extent of excited-state localization is found to be sensitive to both the nature of the defect and the length of the conjugated chains. Implications for resonant energy transfer along conjugated polymer chains are discussed.

Biodegradable Poly(ester urethane)urea Elastomers with Variable Amino Content for Subsequent Functionalization with Phosphorylcholine

PubMed Central

Fang, Jun; Ye, Sang-Ho; Shankarraman, Venkat; Huang, Yixian; Mo, Xiumei; Wagner, William R.

2015-01-01

While surface modification is well suited for imparting biomaterials with specific functionality for favorable cell interactions, the modification of degradable polymers would be expected to provide only temporary benefit. Bulk modification by incorporating pendant reactive groups for subsequent functionalization of biodegradable polymers would provide a more enduring approach. Towards this end, a series of biodegradable poly(ester urethane)urea elastomers with variable amino content (PEUU-NH2 polymers) were developed. Carboxylated phosphorycholine was synthesized and conjugated to the PEUU-NH2 polymers for subsequent bulk functionalization to generate PEUU-PC polymers. Synthesis was verified by 1H NMR, X-ray photoelectron spectroscopy and ATR-FTIR. The impact of amine incorporation and phosphorylcholine conjugation was shown on mechanical, thermal and degradation properties. Water absorption increased with increasing amine content, and further with PC conjugation. In wet conditions, tensile strength and initial modulus generally decreased with increasing hydrophilicity, but remained in the range of 5–30 MPa and 10–20 MPa respectively. PC conjugation was associated with significantly reduced platelet adhesion in blood contact testing and the inhibition of rat vascular smooth muscle cell proliferation. These biodegradable PEUU-PC elastomers offer attractive properties for applications as non-thrombogenic, biodegradable coatings and for blood-contacting scaffold applications. Further, the PEUU-NH2 base polymers offer the potential to have multiple types of biofunctional groups conjugated onto the backbone to address a variety of design objectives. PMID:25132273

Elucidating the Charge Transfer Mechanism in Radical Polymer Thin Films

NASA Astrophysics Data System (ADS)

Mukherjee, Sanjoy; Boudouris, Bryan

The active role of polymers in organic electronics has attracted significant attention in recent decades. Beyond conventional conjugated polymers, recently radical polymers have received a great deal of consideration by the community. Radical polymers are redox-active macromolecules with non-conjugated backbones functionalized with persistent radical sites. Because of their nascent nature, many open questions regarding the physics of their solid-state charge transfer mechanism still exist. In order to address these questions, well-defined radical polymers were synthesized and blended in a manner such that there was tight control over the radical density within the conducting thin films. We demonstrate that the systematic manipulation of the radical-to-radical spacing in open-shell macromolecules leads to exponential changes in the macroscopic electrical conductivity, and temperature-independent charge transport behaviour. Thus, a clear picture emerges that charge transfer in radical polymers is dictated by a tunnelling mechanism between proximal sites. This behavior is consistent with a distinct mechanism similar to redox reactions in biological media, but is unique relative to transport in common conjugated polymers. These results constitute the first experimental insight into the mechanism of solid-state electrical conduction in radical polymers.

Evaluation of hyaluronic acid-protein conjugates for polymer masked-unmasked protein therapy.

PubMed

Ferguson, Elaine L; Alshame, Alshame M J; Thomas, David W

2010-12-15

Bioresponsive polymers may effectively be utilized to enhance the circulation time and stability of biologically active proteins and peptides, while reducing their immunogenicity and toxicity. Recently, dextrin-epidermal growth factor (EGF) conjugates, which make use of the Polymer-masked UnMasked Protein Therapy (PUMPT) concept, have been developed and shown potential as modulators of impaired wound healing. This study investigated the potential of PUMPT using hyaluronic acid (HA) conjugates to mask activity and enhance protein stability, while allowing restoration of biological activity following triggered degradation. HA fragments (Mw ∼90,000g/mol), obtained by acid hydrolysis of Rooster comb HA, were conjugated to trypsin as a model enzyme or to EGF as a model growth factor. Conjugates contained 2.45 and 0.98% (w/w) trypsin or EGF, respectively, and contained <5% free protein. HA conjugation did not significantly alter trypsin's activity. However, incubation of the conjugate with physiological concentrations of HAase increased its activity to ∼145% (p<0.001) that of the free enzyme. In contrast, when HA-EGF conjugates were tested in vitro, no effect on cell proliferation was seen, even in the presence of HAase. HA conjugates did not display typical masking/unmasking behavior, HA-trypsin conjugates exhibited ∼52% greater stability in the presence of elastase, compared to free trypsin, demonstrating the potential of HA conjugates for further development as modulators of tissue repair. Copyright © 2010 Elsevier B.V. All rights reserved.

Synthesis and Exciton Dynamics of Donor-Orthogonal Acceptor Conjugated Polymers: Reducing the Singlet-Triplet Energy Gap.

PubMed

Freeman, David M E; Musser, Andrew J; Frost, Jarvist M; Stern, Hannah L; Forster, Alexander K; Fallon, Kealan J; Rapidis, Alexandros G; Cacialli, Franco; McCulloch, Iain; Clarke, Tracey M; Friend, Richard H; Bronstein, Hugo

2017-08-16

The presence of energetically low-lying triplet states is a hallmark of organic semiconductors. Even though they present a wealth of interesting photophysical properties, these optically dark states significantly limit optoelectronic device performance. Recent advances in emissive charge-transfer molecules have pioneered routes to reduce the energy gap between triplets and "bright" singlets, allowing thermal population exchange between them and eliminating a significant loss channel in devices. In conjugated polymers, this gap has proved resistant to modification. Here, we introduce a general approach to reduce the singlet-triplet energy gap in fully conjugated polymers, using a donor-orthogonal acceptor motif to spatially separate electron and hole wave functions. This new generation of conjugated polymers allows for a greatly reduced exchange energy, enhancing triplet formation and enabling thermally activated delayed fluorescence. We find that the mechanisms of both processes are driven by excited-state mixing between π-π*and charge-transfer states, affording new insight into reverse intersystem crossing.

In situ measurements of the optical absorption of dioxythiophene-based conjugated polymers

NASA Astrophysics Data System (ADS)

Hwang, J.; Schwendeman, I.; Ihas, B. C.; Clark, R. J.; Cornick, M.; Nikolou, M.; Argun, A.; Reynolds, J. R.; Tanner, D. B.

2011-05-01

Conjugated polymers can be reversibly doped by electrochemical means. This doping introduces new subband-gap optical absorption bands in the polymer while decreasing the band-gap absorption. To study this behavior, we have prepared an electrochemical cell allowing in situ measurements of the optical properties of the polymer. The cell consists of a thin polymer film deposited on gold-coated Mylar behind which is another polymer that serves as a counterelectrode. An infrared transparent window protects the upper polymer from ambient air. By adding a gel electrolyte and making electrical connections to the polymer-on-gold films, one may study electrochromism in a wide spectral range. As the cell voltage (the potential difference between the two electrodes) changes, the doping level of the conjugated polymer films is changed reversibly. Our experiments address electrochromism in poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-dimethylpropylenedioxythiophene) (PProDOT-Me2). This closed electrochemical cell allows the study of the doping induced subband-gap features (polaronic and bipolaronic modes) in these easily oxidized and highly redox switchable polymers. We also study the changes in cell spectra as a function of polymer thickness and investigate strategies to obtain cleaner spectra, minimizing the contributions of water and gel electrolyte features.

Self-Assembly of Telechelic Tyrosine End-Capped PEO Star Polymers in Aqueous Solution.

PubMed

Edwards-Gayle, Charlotte J C; Greco, Francesca; Hamley, Ian W; Rambo, Robert P; Reza, Mehedi; Ruokolainen, Janne; Skoulas, Dimitrios; Iatrou, Hermis

2018-01-08

We investigate the self-assembly of two telechelic star polymer-peptide conjugates based on poly(ethylene oxide) (PEO) four-arm star polymers capped with oligotyrosine. The conjugates were prepared via N-carboxy anhydride-mediated ring-opening polymerization from PEO star polymer macroinitiators. Self-assembly occurs above a critical aggregation concentration determined via fluorescence probe assays. Peptide conformation was examined using circular dichroism spectroscopy. The structure of self-assembled aggregates was probed using small-angle X-ray scattering and cryogenic transmission electron microscopy. In contrast to previous studies on linear telechelic PEO-oligotyrosine conjugates that show self-assembly into β-sheet fibrils, the star architecture suppresses fibril formation and micelles are generally observed instead, a small population of fibrils only being observed upon pH adjustment. Hydrogelation is also suppressed by the polymer star architecture. These peptide-functionalized star polymer solutions are cytocompatible at sufficiently low concentration. These systems present tyrosine at high density and may be useful in the development of future enzyme or pH-responsive biomaterials.

A high-throughput screening approach for the optoelectronic properties of conjugated polymers.

PubMed

Wilbraham, Liam; Berardo, Enrico; Turcani, Lukas; Jelfs, Kim E; Zwijnenburg, Martijn A

2018-06-25

We propose a general high-throughput virtual screening approach for the optical and electronic properties of conjugated polymers. This approach makes use of the recently developed xTB family of low-computational-cost density functional tight-binding methods from Grimme and co-workers, calibrated here to (TD-)DFT data computed for a representative diverse set of (co-)polymers. Parameters drawn from the resulting calibration using a linear model can then be applied to the xTB derived results for new polymers, thus generating near DFT-quality data with orders of magnitude reduction in computational cost. As a result, after an initial computational investment for calibration, this approach can be used to quickly and accurately screen on the order of thousands of polymers for target applications. We also demonstrate that the (opto)electronic properties of the conjugated polymers show only a very minor variation when considering different conformers and that the results of high-throughput screening are therefore expected to be relatively insensitive with respect to the conformer search methodology applied.

Electroactive polymer-peptide conjugates for adhesive biointerfaces.

PubMed

Maione, Silvana; Gil, Ana M; Fabregat, Georgina; Del Valle, Luis J; Triguero, Jordi; Laurent, Adele; Jacquemin, Denis; Estrany, Francesc; Jiménez, Ana I; Zanuy, David; Cativiela, Carlos; Alemán, Carlos

2015-10-15

Electroactive polymer-peptide conjugates have been synthesized by combining poly(3,4-ethylenedioxythiophene), a polythiophene derivative with outstanding properties, and an Arg-Gly-Asp (RGD)-based peptide in which Gly has been replaced by an exotic amino acid bearing a 3,4-ethylenedioxythiophene ring in the side chain. The incorporation of the peptide at the ends of preformed PEDOT chains has been corroborated by both FTIR and X-ray photoelectron spectroscopy. Although the morphology and topology are not influenced by the incorporation of the peptide at the ends of PEDOT chains, this process largely affects other surface properties. Thus, the wettability of the conjugates is considerably higher than that of PEDOT, independently of the synthetic strategy, whereas the surface roughness only increases when the conjugate is obtained using a competing strategy (i.e. growth of the polymer chains against termination by end capping). The electrochemical activity of the conjugates has been found to be higher than that of PEDOT, evidencing the success of the polymer-peptide links designed by chemical similarity. Density functional theory calculations have been used not only to ascertain the conformational preferences of the peptide but also to interpret the electronic transitions detected by UV-vis spectroscopy. Electroactive surfaces prepared using the conjugates displayed the higher bioactivities in terms of cell adhesion, with the relative viabilities being dependent on the roughness, wettability and electrochemical activity of the conjugate. In addition to the influence of the peptide fragment in the initial cell attachment and subsequent cell spreading and survival, the results indicate that PEDOT promotes the exchange of ions at the conjugate-cell interface.

An easy and effective method to modulate molecular energy level of the polymer based on benzodithiophene for the application in polymer solar cells.

PubMed

Zhang, Maojie; Guo, Xia; Ma, Wei; Zhang, Shaoqing; Huo, Lijun; Ade, Harald; Hou, Jianhui

2014-04-02

Attaching meta-alkoxy-phenyl groups as conjugated side chains is an easy and effective way to modulate the molecular energy level of D-A polymer for photovoltaic application, and the polymer solar cells based on the polymer consisting meta-alkoxy-phenyl groups as conjugated side chain, PBT-OP, shows an enhanced open circuit voltage and thus higher efficiency of 7.50%, under the illumination of AM 1.5G, 100 mW/cm(2) . © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Emerging applications of conjugated polymers in molecular imaging.

PubMed

Li, Junwei; Liu, Jie; Wei, Chen-Wei; Liu, Bin; O'Donnell, Matthew; Gao, Xiaohu

2013-10-28

In recent years, conjugated polymers have attracted considerable attention from the imaging community as a new class of contrast agent due to their intriguing structural, chemical, and optical properties. Their size and emission wavelength tunability, brightness, photostability, and low toxicity have been demonstrated in a wide range of in vitro sensing and cellular imaging applications, and have just begun to show impact in in vivo settings. In this Perspective, we summarize recent advances in engineering conjugated polymers as imaging contrast agents, their emerging applications in molecular imaging (referred to as in vivo uses in this paper), as well as our perspectives on future research.

BRCAA1 antibody- and Her2 antibody-conjugated amphiphilic polymer engineered CdSe/ZnS quantum dots for targeted imaging of gastric cancer

NASA Astrophysics Data System (ADS)

Li, Chao; Ji, Yang; Wang, Can; Liang, Shujing; Pan, Fei; Zhang, Chunlei; Chen, Feng; Fu, Hualin; Wang, Kan; Cui, Daxiang

2014-05-01

Successful development of safe and highly effective nanoprobes for targeted imaging of in vivo early gastric cancer is a great challenge. Herein, we choose the CdSe/ZnS (core-shell) quantum dots (QDs) as prototypical materials, synthesized one kind of a new amphiphilic polymer including dentate-like alkyl chains and multiple carboxyl groups, and then used the prepared amphiphilic polymer to modify QDs. The resultant amphiphilic polymer engineered QDs (PQDs) were conjugated with BRCAA1 and Her2 monoclonal antibody, and prepared BRCAA1 antibody- and Her2 antibody-conjugated QDs were used for in vitro MGC803 cell labeling and in vivo targeted imaging of gastric cancer cells. Results showed that the PQDs exhibited good water solubility, strong photoluminescence (PL) intensity, and good biocompatibility. BRCAA1 antibody- and Her2 antibody-conjugated QD nanoprobes successfully realized targeted imaging of in vivo gastric cancer MGC803 cells. In conclusion, BRCAA1 antibody- and Her2 antibody-conjugated PQDs have great potential in applications such as single cell labeling and in vivo tracking, and targeted imaging and therapeutic effects' evaluation of in vivo early gastric cancer cells in the near future.

Peptide/protein-polymer conjugates: synthetic strategies and design concepts.

PubMed

Gauthier, Marc A; Klok, Harm-Anton

2008-06-21

This feature article provides a compilation of tools available for preparing well-defined peptide/protein-polymer conjugates, which are defined as hybrid constructs combining (i) a defined number of peptide/protein segments with uniform chain lengths and defined monomer sequences (primary structure) with (ii) a defined number of synthetic polymer chains. The first section describes methods for post-translational, or direct, introduction of chemoselective handles onto natural or synthetic peptides/proteins. Addressed topics include the residue- and/or site-specific modification of peptides/proteins at Arg, Asp, Cys, Gln, Glu, Gly, His, Lys, Met, Phe, Ser, Thr, Trp, Tyr and Val residues and methods for producing peptides/proteins containing non-canonical amino acids by peptide synthesis and protein engineering. In the second section, methods for introducing chemoselective groups onto the side-chain or chain-end of synthetic polymers produced by radical, anionic, cationic, metathesis and ring-opening polymerization are described. The final section discusses convergent and divergent strategies for covalently assembling polymers and peptides/proteins. An overview of the use of chemoselective reactions such as Heck, Sonogashira and Suzuki coupling, Diels-Alder cycloaddition, Click chemistry, Staudinger ligation, Michael's addition, reductive alkylation and oxime/hydrazone chemistry for the convergent synthesis of peptide/protein-polymer conjugates is given. Divergent approaches for preparing peptide/protein-polymer conjugates which are discussed include peptide synthesis from synthetic polymer supports, polymerization from peptide/protein macroinitiators or chain transfer agents and the polymerization of peptide side-chain monomers.

Hydrophobic-Sheath Segregated Macromolecular Fluorophores: Colloidal Nanoparticles of Polycaprolactone-Grafted Conjugated Polymers with Bright Far-Red/Near-Infrared Emission for Biological Imaging.

PubMed

Yang, Cangjie; Liu, Hui; Zhang, Yingdan; Xu, Zhigang; Wang, Xiaochen; Cao, Bin; Wang, Mingfeng

2016-05-09

This article describes molecular design, synthesis and characterization of colloidal nanoparticles containing polycaprolactone-grafted conjugated polymers that exhibit strong far red/near-infrared (FR/NIR) fluorescence for bioimaging. Specifically, we synthesized two kinds of conjugated polymer bottle brushes (PFTB(out)-g-PCL and PFTB(in)-g-PCL) with different positions of the hexyl groups on the thiophene rings. A synthetic amphiphilic block copolymer PCL-b-POEGMA was employed as surfactants to encapsulate PFTB-g-PCL polymers into colloidal nanoparticles (denoted as "nanoREDs") in aqueous media. The chain length of the PCL side chains in PFTB-g-PCL played a critical role in determining the fluorescence properties in both bulk solid states and the colloidal nanoparticles. Compared to semiconducting polymer dots (Pdots) composed of PFTB(out) without grafted PCL, nanoRED(out) showed at least four times higher fluorescence quantum yield (∼20%) and a broader emission band centered at 635 nm. We further demonstrated the application of this new class of nanoREDs for effective labeling of L929 cells and HeLa cancer cells with good biocompatibility. This strategy of hydrophobic-sheath segregated macromolecular fluorophores is expected to be applicable to a broad range of conjugated polymers with tunable optical properties for applications such as bioimaging.

Tracking the coherent generation of polaron pairs in conjugated polymers

NASA Astrophysics Data System (ADS)

de Sio, Antonietta; Troiani, Filippo; Maiuri, Margherita; Réhault, Julien; Sommer, Ephraim; Lim, James; Huelga, Susana F.; Plenio, Martin B.; Rozzi, Carlo Andrea; Cerullo, Giulio; Molinari, Elisa; Lienau, Christoph

2016-12-01

The optical excitation of organic semiconductors not only generates charge-neutral electron-hole pairs (excitons), but also charge-separated polaron pairs with high yield. The microscopic mechanisms underlying this charge separation have been debated for many years. Here we use ultrafast two-dimensional electronic spectroscopy to study the dynamics of polaron pair formation in a prototypical polymer thin film on a sub-20-fs time scale. We observe multi-period peak oscillations persisting for up to about 1 ps as distinct signatures of vibronic quantum coherence at room temperature. The measured two-dimensional spectra show pronounced peak splittings revealing that the elementary optical excitations of this polymer are hybridized exciton-polaron-pairs, strongly coupled to a dominant underdamped vibrational mode. Coherent vibronic coupling induces ultrafast polaron pair formation, accelerates the charge separation dynamics and makes it insensitive to disorder. These findings open up new perspectives for tailoring light-to-current conversion in organic materials.

Dual-Color Fluorescence Imaging of Magnetic Nanoparticles in Live Cancer Cells Using Conjugated Polymer Probes

PubMed Central

Sun, Minjie; Sun, Bin; Liu, Yun; Shen, Qun-Dong; Jiang, Shaojun

2016-01-01

Rapid growth in biological applications of nanomaterials brings about pressing needs for exploring nanomaterial-cell interactions. Cationic blue-emissive and anionic green-emissive conjugated polymers are applied as dual-color fluorescence probes to the surface of negatively charged magnetic nanoparticles through sequentially electrostatic adsorption. These conjugated polymers have large extinction coefficients and high fluorescence quantum yield (82% for PFN and 62% for ThPFS). Thereby, one can visualize trace amount (2.7 μg/mL) of fluorescence-labeled nanoparticles within cancer cells by confocal laser scanning microscopy. Fluorescence labeling by the conjugated polymers is also validated for quantitative determination of the internalized nanoparticles in each individual cell by flow cytometry analysis. Extensive overlap of blue and green fluorescence signals in the cytoplasm indicates that both conjugated polymer probes tightly bind to the surface of the nanoparticles during cellular internalization. The highly charged and fluorescence-labeled nanoparticles non-specifically bind to the cell membranes, followed by cellular uptake through endocytosis. The nanoparticles form aggregates inside endosomes, which yields a punctuated staining pattern. Cellular internalization of the nanoparticles is dependent on the dosage and time. Uptake efficiency can be enhanced three-fold by application of an external magnetic field. The nanoparticles are low cytotoxicity and suitable for simultaneously noninvasive fluorescence and magnetic resonance imaging application. PMID:26931282

Measuring Exciton Diffusion in Conjugated Polymer Films with Super-resolution Microscopy

NASA Astrophysics Data System (ADS)

Penwell, Samuel; Ginsberg, Lucas; Noriega Manez, Rodrigo; Ginsberg, Naomi

2015-03-01

Conjugated polymers are highly tunable organic semiconductors, which can be solution processed to form thin films, making them prime candidates for organic photovoltaic devices. One of the most important parameters in a conjugated polymer solar cell is the exciton diffusion length, which depends on intermolecular couplings, and is typically on the order of 10 nm. This mean exciton migration can vary dramatically between films and within a single film due to heterogeneities in morphology on length scales of 10's to 100's nm. To study the variability of exciton diffusion and morphology within individual conjugated polymer films, we are adapting stimulated emission depletion microscopy. STED is typically used in biology with well-engineered fluorescent labels or on NV-centers in diamond. I will, however, describe how we have demonstrated STED in conjugated polymer films of MEH-PPV and CN-PPV by taking care to first understand the film's photophysical properties. This new approach provides a way to study exciton diffusion by utilizing subdiffraction optical excitation volumes. In this way, we will obtain a spatiotemporal map of exciton distributions that will help to correlate the energetic landscape to film morphology at the nanoscale. This research is supported in part by the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), made possible in part by the American Recovery and Reinvestment Act of 2009, administered by ORISE-ORAU under Contract No. DE-AC05-06.

Organic arsenicals as efficient and highly specific linkers for protein/peptide-polymer conjugation.

PubMed

Wilson, Paul; Anastasaki, Athina; Owen, Matthew R; Kempe, Kristian; Haddleton, David M; Mann, Sarah K; Johnston, Angus P R; Quinn, John F; Whittaker, Michael R; Hogg, Philip J; Davis, Thomas P

2015-04-01

The entropy-driven affinity of trivalent (in)organic arsenicals for closely spaced dithiols has been exploited to develop a novel route to peptide/protein-polymer conjugation. A trivalent arsenous acid (As(III)) derivative (1) obtained from p-arsanilic acid (As(V)) was shown to readily undergo conjugation to the therapeutic peptide salmon calcitonin (sCT) via bridging of the Cys(1)-Cys(7) disulfide, which was verified by RP-HPLC and MALDI-ToF-MS. Conjugation was shown to proceed rapidly (t < 2 min) in situ and stoichiometrically through sequential reduction-conjugation protocols, therefore exhibiting conjugation efficiencies equivalent to those reported for the current leading disulfide-bond targeting strategies. Furthermore, using bovine serum albumin as a model protein, the trivalent organic arsenical 1 was found to demonstrate enhanced specificity for disulfide-bond bridging in the presence of free cysteine residues relative to established maleimide functional reagents. This specificity represents a shift toward potential orthogonality, by clearly distinguishing between the reactivity of mono- and disulfide-derived (vicinal or neighbors-through-space) dithiols. Finally, p-arsanilic acid was transformed into an initiator for aqueous single electron-transfer living radical polymerization, allowing the synthesis of hydrophilic arsenic-functional polymers which were shown to exhibit negligible cytotoxicity relative to a small molecule organic arsenical, and an unfunctionalized polymer control. Poly(poly[ethylene glycol] methyl ether acrylate) (PPEGA480, DPn = 10, Mn,NMR = 4900 g·mol(-1), Đ = 1.07) possessing a pentavalent arsenic acid (As(V)) α-chain end was transformed into trivalent As(III) post-polymerization via initial reduction by biological reducing agent glutathione (GSH), followed by binding of GSH. Conjugation of the resulting As(III)-functional polymer to sCT was realized within 35 min as indicated by RP-HPLC and verified later by thermodynamically driven release of sCT, from the conjugate, in the presence of strong chelating reagent ethanedithiol.

A new formulation of curcumin using poly (lactic-co-glycolic acid)—polyethylene glycol diblock copolymer as carrier material

NASA Astrophysics Data System (ADS)

Phuong Tuyen Dao, Thi; Hoai Nguyen, To; To, Van Vinh; Ho, Thanh Ha; Nguyen, Tuan Anh; Chien Dang, Mau

2014-09-01

The aim of this study is to fabricate a nanoparticle formulation of curcumin using a relatively new vehicle as the matrix polymer: poly(lactic-co-glycolic acid) (PLGA)- polyethylene glycol (PEG) diblock copolymer, and to investigate the effects of the various processing parameters on the characteristics of nanoparticles (NPs). We successfully synthesized the matrix polymer of PLGA-PEG by conjugation of PLGA copolymer with a carboxylate end group to a heterobifunctional amine-PEG-methoxy using N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide as conjugation crosslinkers. The composition of the formed product (PLGA-PEG) was characterized with 500 MHz 1H nuclear magnetic resonance (NMR). The conjugation of PLGA-PEG was confirmed using Fourier transform infrared (FTIR) spectrum study. This diblock copolymer was then used to prepare the curcumin-loaded NPs through nanoprecipitation technique. With this method, we found that the size distribution depends on the type of solvent, the concentration of polymer and the concentration of surfactant. The particle size and size distribution were measured by dynamic light scattering (DLS). Transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to confirm the size, structure and morphology of the successfully prepared NPs. All of our results showed that they are spherical and quite homologous with mean diameter around of 100-300 nm. Further, we evaluated encapsulation efficiency and some characteristics of NPs through high performance liquid chromatography (HPLC) analyses, zeta-potential measurements and x-ray diffraction studies. The HPLC analyses were performed to determine the amount of curcumin entrapped in NPs. The zeta-potential measurements confirmed the stability of NPs and the successful encapsulation of curcumin within NPs and the x-ray diffraction patterns showed the disordered-crystalline phase of curcumin inside the polymeric matrix.

Second and third order nonlinear optical properties of conjugated molecules and polymers

NASA Technical Reports Server (NTRS)

Perry, Joseph W.; Stiegman, Albert E.; Marder, Seth R.; Coulter, Daniel R.; Beratan, David N.; Brinza, David E.

1988-01-01

Second- and third-order nonlinear optical properties of some newly synthesized organic molecules and polymers are reported. Powder second-harmonic-generation efficiencies of up to 200 times urea have been realized for asymmetric donor-acceptor acetylenes. Third harmonic generation chi(3)s have been determined for a series of small conjugated molecules in solution. THG chi(3)s have also been determined for a series of soluble conjugated copolymers prepared using ring-opening metathesis polymerization. The results are discussed in terms of relevant molecular and/or macroscopic structural features of these conjugated organic materials.

Recent Developments in C-H Activation for Materials Science in the Center for Selective C-H Activation.

PubMed

Zhang, Junxiang; Kang, Lauren J; Parker, Timothy C; Blakey, Simon B; Luscombe, Christine K; Marder, Seth R

2018-04-16

Abstract : Organic electronics is a rapidly growing field driven in large part by the synthesis of ∏-conjugated molecules and polymers. Traditional aryl cross-coupling reactions such as the Stille and Suzuki have been used extensively in the synthesis of ∏-conjugated molecules and polymers, but the synthesis of intermediates necessary for traditional cross-couplings can include multiple steps with toxic and hazardous reagents. Direct arylation through C-H bond activation has the potential to reduce the number of steps and hazards while being more atom-economical. Within the Center for Selective C-H Functionalization (CCHF), we have been developing C-H activation methodology for the synthesis of ∏-conjugated materials of interest, including direct arylation of difficult-to-functionalize electron acceptor intermediates and living polymerization of ∏-conjugated polymers through C-H activation.

Thermo-reversible morphology and conductivity of a conjugated polymer network embedded in polymeric self-assembly

NASA Astrophysics Data System (ADS)

Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe; Li, Yunchao; Hong, Kunlun; Sumpter, Bobby G.; Ohl, Michael; Paranthaman, Mariappan Parans; Smith, Gregory S.; Do, Changwoo

Self-assembly of block copolymers provides opportunities to create nano hybrid materials, utilizing self-assembled micro-domains with a variety of morphology and periodic architectures as templates for functional nano-fillers. Here we report new progress towards the fabrication of a thermally responsive conducting polymer self-assembly made from a water-soluble poly(thiophene) derivative with short PEO side chains and Pluronic L62 solution in water. The structural and electrical properties of conjugated polymer-embedded nanostructures were investigated by combining SANS, SAXS, CGMD simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporating them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellar-to-lamellar phase transition defines the embedded conjugated polymer network. The conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. The research was sponsored by the Scientific User Facilities Division, Office of BES, U.S. DOE and Laboratory Directed Research and Development Program of ORNL, managed by UT-Battelle, LLC.

Design, synthesis, and structure-property relationships of isoindigo-based conjugated polymers.

PubMed

Lei, Ting; Wang, Jie-Yu; Pei, Jian

2014-04-15

Conjugated polymers have developed rapidly due to their promising applications in low-cost, lightweight, and flexible electronics. The development of the third-generation donor-acceptor (D-A) polymers greatly improved the device performance in organic solar cells (OSCs) and field-effect transistors (FETs). However, for further improvement of device performance, scientists need to develop new building blocks, in particular electron-deficient aromatics, and gain an in-depth understanding of the structure-property relationships. Recently, isoindigo has been used as a new acceptor of D-A conjugated polymers. An isomer of indigo, isoindigo is a less well-known dye and can be isolated as a by-product from certain biological processes. It has two lactam rings and exhibits strong electron-withdrawing character. This electron deficiency gives isoindigo-based polymers intriguing properties, such as broad absorption and high open circuit voltage in OSCs, as well as high mobility and good ambient stability in FETs. In this Account, we review our recent progress on the design, synthesis, and structure-property relationship study of isoindigo-based polymers for FETs. Starting with some discussion on carrier transport in polymer films, we provide some basic strategies towards high-performance polymer FETs. We discuss the stability issue of devices, the impediment of the alkyl side chains, and the choice of the donor part of conjugated polymers. We demonstrate that introducing the isoindigo core effectively lowers the HOMO levels of polymers and provides FETs with long-time stability. In addition, we have found that when we use inappropriate alkyl side chains or non-centrosymmetric donors, the device performance of isoindigo polymers suffers. To further improve device performance and ambient stability, we propose several design strategies, such as using farther branched alkyl chains, modulating polymer energy levels, and extending π-conjugated backbones. We have found that using farther branched alkyl chains can effectively decrease interchain π-π stacking distance and improve carrier mobility. When we introduce electron-deficient functional groups on the isoindigo core, the LUMO levels of the polymers markedly decrease, which significantly improves the electron mobility and device stability. In addition, we present a new polymer system called BDOPV, which is based on the concept of π-extended isoindigo. By application of some strategies successfully used in isoindigo-based polymers, BDOPV-based polymers exhibit high mobility and good stability both in n-type and in ambipolar FETs. We believe that a synergy of molecular engineering strategies towards the isoindigo core, donor units, and side chains may further improve the performance and broaden the application of isoindigo-based polymers.

Non-Fullerene Polymer Solar Cells Based on Alkylthio and Fluorine Substituted 2D-Conjugated Polymers Reach 9.5% Efficiency.

PubMed

Bin, Haijun; Zhang, Zhi-Guo; Gao, Liang; Chen, Shanshan; Zhong, Lian; Xue, Lingwei; Yang, Changduk; Li, Yongfang

2016-04-06

Non-fullerene polymer solar cells (PSCs) with solution-processable n-type organic semiconductor (n-OS) as acceptor have seen rapid progress recently owing to the synthesis of new low bandgap n-OS, such as ITIC. To further increase power conversion efficiency (PCE) of the devices, it is of a great challenge to develop suitable polymer donor material that matches well with the low bandgap n-OS acceptors thus providing complementary absorption and nanoscaled blend morphology, as well as suppressed recombination and minimized energy loss. To address this challenge, we synthesized three medium bandgap 2D-conjugated bithienyl-benzodithiophene-alt-fluorobenzotriazole copolymers J52, J60, and J61 for the application as donor in the PSCs with low bandgap n-OS ITIC as acceptor. The three polymers were designed with branched alkyl (J52), branched alkylthio (J60), and linear alkylthio (J61) substituent on the thiophene conjugated side chain of the benzodithiophene (BDT) units for studying effect of the substituents on the photovoltaic performance of the polymers. The alkylthio side chain, red-shifted absorption down-shifted the highest occupied molecular orbital (HOMO) level and improved crystallinity of the 2D conjugated polymers. With linear alkylthio side chain, the tailored polymer J61 exhibits an enhanced JSC of 17.43 mA/cm(2), a high VOC of 0.89 V, and a PCE of 9.53% in the best non-fullerene PSCs with the polymer as donor and ITIC as acceptor. To the best of our knowledge, the PCE of 9.53% is one of the highest values reported in literature to date for the non-fullerene PSCs. The results indicate that J61 is a promising medium bandgap polymer donor in non-fullerene PSCs.

Hydrophilic Conjugated Polymers with Large Bandgaps and Deep-Lying HOMO Levels as an Efficient Cathode Interlayer in Inverted Polymer Solar Cells.

PubMed

Kan, Yuanyuan; Zhu, Yongxiang; Liu, Zhulin; Zhang, Lianjie; Chen, Junwu; Cao, Yong

2015-08-01

Two hydrophilic conjugated polymers, PmP-NOH and PmP36F-NOH, with polar diethanol-amine on the side chains and main chain structures of poly(meta-phenylene) and poly(meta-phenylene-alt-3,6-fluorene), respectively, are successfully synthesized. The films of PmP-NOH and PmP36F-NOH show absorption edges at 340 and 343 nm, respectively. The calculated optical bandgaps of the two polymers are 3.65 and 3.62 eV, respectively, the largest ones so far reported for hydrophilic conjugated polymers. PmP-NOH and PmP36F-NOH also possess deep-lying highest occupied molecular orbital levels of -6.19 and -6.15 eV, respectively. Inserting PmP-NOH and PmP36F-NOH as a cathode interlayer in inverted polymer solar cells with a PTB7/PC71 BM blend as the active layer, high power conversion efficiencies of 8.58% and 8.33%, respectively, are achieved, demonstrating that the two hydrophilic polymers are excellent interlayers for efficient inverted polymer solar cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel Conjugated Polymers Prepared by Direct (Hetero) arylation: An Eco-Friendly Tool for Organic Electronics.

PubMed

Liu, Fuchuan; Zhang, Yangqian; Wang, Hang; Zhang, Shiming

2018-02-13

The phthalimide (PhI) moiety has been attracting more attention as an excellent acceptor building block in donor-acceptor (D-A) conjugated polymers. In this paper; three D-A conjugated polymers with or without thiocarbonyl moieties are successfully prepared by the direct (hetero)-arylation polymerization (DHAP), which is an atom efficient and facile synthetic strategy to obtain polymer materials. Compared with the traditional carbon-carbon coupling reactions, this method possesses more advantages, including: fewer synthetic steps, avoidance of the preparation of the organometallic reagents, higher atom economy and fewer toxic byproducts, better compatibility with chemically sensitive functional groups and so on. All three of these designed PhI-based polymers exhibited favourable optoelectronic and thermal performance. The optical, thermodynamic and electrochemical properties of the synthesized polymers were systematically investigated using ultraviolet-visible (UV-vis) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and cyclic voltammetry (CV). The results of these three polymers indicated that thionation of the carbonyl was a highly effective methods to improve the properties of PhI-based polymers; and provided impetus for the development of thionated PhI derivatives for organic electronic applications.

Axial and radial nanostructures in electrospun polymer fibers

NASA Astrophysics Data System (ADS)

Greenfeld, Israel; Camposeo, Andrea; Tantussi, Francesco; Pagliara, Stefano; Fuso, Francesco; Allegrini, Maria; Pisignano, Dario; Zussman, Eyal

2013-03-01

The high tensional stresses during electrospinning of semidilute polymer solutions affect the dynamic conformation of the polymer network within the liquid jet, leaving a distinctive trace in the molecular structure after solidification. We investigated such effects in electrospun nanofibers made of conjugated polymers. Modeling the polymer network evolution during electrospinning showed that as the network stretches axially, it contracts towards the jet core. The model represents the semi-flexible conjugated polymer chains as flexible freely-jointed chains, whose joints are bonding defects. Using the conjugated polymer MEH-PPV dissolved in a mixture of THF and DMF solvents, and taking advantage of its unique photophysical characteristics, we investigated optically the variations in the density and orientation of the polymer macromolecules in electrospun nanofibers. In agreement with our model, we found higher density and axial orientation at the fiber core, while lower density and radial orientation closer to the fiber surface. The non-uniformity of the resulting molecular structure can be tuned and exploited in diverse optical and structural applications. We acknowledge: V. Fasano, G. Potente, S. Girardo and E. Caldi for assistance in measurements; United States-Israel BSF, RBNI Institute, and the Israel Science Foundation for financial support.

How Many Parameters Actually Affect the Mobility of Conjugated Polymers?

NASA Astrophysics Data System (ADS)

Fornari, Rocco P.; Blom, Paul W. M.; Troisi, Alessandro

2017-02-01

We describe charge transport along a polymer chain with a generic theoretical model depending in principle on tens of parameters, reflecting the chemistry of the material. The charge carrier states are obtained from a model Hamiltonian that incorporates different types of disorder and electronic structure (e.g., the difference between homo- and copolymer). The hopping rate between these states is described with a general rate expression, which contains the rates most used in the literature as special cases. We demonstrate that the steady state charge mobility in the limit of low charge density and low field ultimately depends on only two parameters: an effective structural disorder and an effective electron-phonon coupling, weighted by the size of the monomer. The results support the experimental observation [N. I. Craciun, J. Wildeman, and P. W. M. Blom, Phys. Rev. Lett. 100, 056601 (2008), 10.1103/PhysRevLett.100.056601] that the mobility in a broad range of (polymeric) semiconductors follows a universal behavior, insensitive to the chemical detail.

Antibiotic-containing polymers for localized, sustained drug delivery

PubMed Central

Stebbins, Nicholas D.; Ouimet, Michelle A.; Uhrich, Kathryn E.

2014-01-01

Many currently used antibiotics suffer from issues such as systemic toxicity, short half-life, and increased susceptibility to bacterial resistance. Although most antibiotic classes are administered systemically through oral or intravenous routes, a more efficient delivery system is needed. This review discusses the chemical conjugation of antibiotics to polymers, achieved by forming covalent bonds between antibiotics and a pre-existing polymer or by developing novel antibiotic-containing polymers. Through conjugating antibiotics to polymers, unique polymer properties can be taken advantage of. These polymeric antibiotics display controlled, sustained drug release and vary in antibiotic class type, synthetic method, polymer composition, bond lability, and antibacterial activity. The polymer synthesis, characterization, drug release, and antibacterial activities, if applicable, will be presented to offer a detailed overview of each system. PMID:24751888

Intracellular delivery and trafficking dynamics of a lymphoma-targeting antibody-polymer conjugate

PubMed Central

Berguig, Geoffrey Y.; Convertine, Anthony J.; Shi, Julie; Palanca-Wessels, Maria Corinna; Duvall, Craig L.; Pun, Suzie H.; Press, Oliver W.; Stayton, Patrick S.

2012-01-01

Ratiometric fluorescence and cellular fractionation studies were employed to characterize the intracellular trafficking dynamics of antibody-poly(propylacrylic acid) (PPAA) conjugates in CD22+ RAMOS-AW cells. The HD39 monoclonal antibody (mAb) directs CD22-dependent, receptor-mediated uptake in human B-cell lymphoma cells where it is rapidly trafficked to the lysosomal compartment. To characterize the intracellular-releasing dynamics of the polymer-mAb conjugates, HD39-streptavidin (HD39/SA) was dual-labeled with pH-insensitive Alex Fluor 488 and pH-sensitive pHrodo fluorophores. The subcellular pH-distribution of the HD39/SA-polymer conjugates were quantified as a function of time by live-cell fluorescence microscopy, and the average intracellular pH values experienced by the conjugates were also characterized as a function of time by flow cytometry. PPAA was shown to strongly alter the intracellular trafficking kinetics compared to HD39/SA alone or HD39/SA conjugates with a control polymer, poly(methacryclic acid) (PMAA). Subcellular trafficking studies revealed that after 6 hours only 11% of the HD39/SA-PPAA conjugates had been trafficked to acidic lysosomal compartments with values at or below pH 5.6. In contrast the average intracellular pH of HD39/SA alone dropped from pH 6.7 ± 0.2 at 1 hour to pH 5.6 ± 0.5 after 3 hours and pH 4.7 ± 0.6 after 6 hours. Conjugation of the control PMAA to HD39/SA showed an average pH drop similar to HD39/SA. Subcellular fractionation studies with tritium-labeled HD39/SA demonstrated that after 6 hours, 89% of HD39/SA was associated with endosomes (Rab5+) and lysosomes (Lamp2+), while 45% of HD39/SA-PPAA was translocated to the cytosol (lactate dehydrogenase+). These results demonstrate the endosomal-releasing properties of PPAA with antibody-polymer conjugates and detail their intracellular trafficking dynamics and subcellular compartmental distributions over time. PMID:23075320

Simulations of singlet exciton diffusion in organic semiconductors: a review

DOE PAGES

Bjorgaard, Josiah A.; Kose, Muhammet Erkan

2014-12-22

Our review describes the various aspects of simulation strategies for exciton diffusion in condensed phase thin films of organic semiconductors. Several methods for calculating energy transfer rate constants are discussed along with procedures for how to account for energetic disorder. Exciton diffusion can be modelled by using kinetic Monte-Carlo methods or master equations. Recent literature on simulation efforts for estimating exciton diffusion lengths of various conjugated polymers and small molecules are introduced. Moreover, these studies are discussed in the context of the effects of morphology on exciton diffusion and the necessity of accurate treatment of disorder for comparison of simulationmore » results with those of experiment.« less

Peptides: important tools for the treatment of central nervous system disorders.

PubMed

Malavolta, Luciana; Cabral, Francisco Romero

2011-10-01

This review shows some classical applications of peptides and suggests there is great promise for the treatment of various central nervous system diseases. Actually, peptides are considered the new generation of biologically active tools because they are key regulators in cellular and intercellular physiological responses, which possess enormous potential for the treatment of various diseases. In spite of their clinical potential, native peptides have seen limited use due to their poor bioavailability and low stability in physiological conditions. Moreover, most peptide or protein pharmaceuticals currently in use are delivered by invasive routes such as via subcutaneous injection. Considerable efforts have been made to design new drugs based on peptides and recent developments in technology and science have provided the means and opportunity to produce a stable as well as controlled-release form of peptide and protein drugs to combat poorly controlled diseases and to increase patients' quality of life. A major challenge in this regard, however, is the delivery of peptides over the blood-brain barrier. This review gives an overview of some strategies used to improve both bioavailability and uptake of peptide drugs for delivery into the brain. Indeed, recent findings suggest that the use of peptides by conjugation to a polymer such as nanoparticles can offer tremendous hope in the treatment of brain disorders. The polymer conjugation improves pharmacokinetics by increasing the molecular mass of proteins and peptides and shielding them from proteolytic enzymes. These new strategies will create new opportunities for the future development of neurotherapeutic drugs. In the present review we have focused our attention on the peptide controlled delivery, summarizing literature reports on the use of peptides and nanotechnology for the treatment and diagnosis of brain disorders. Copyright © 2011 Elsevier Ltd. All rights reserved.

Alkynylation of Bio-Based 5-Hydroxymethylfurfural to Connect Biomass Processing with Conjugated Polymers and Furanic Pharmaceuticals.

PubMed

Romashov, Leonid V; Ananikov, Valentine P

2017-10-18

Acetylene-functionalized platform chemicals were synthesized from biomass-derived 5-hydrohymethylfurfural (HMF). Demanding mono- and bis-ethynylfurans were obtained in high yields (89-99 %). Applications of these products in the synthesis of smart organic conjugated materials and pharmaceuticals were examined in a series of transformations. Conjugated polyacetylenic polymers with morphology control have been prepared by incorporation of the HMF core. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanohybrid conjugated polyelectrolytes: highly photostable and ultrabright nanoparticles.

PubMed

Darwish, Ghinwa H; Karam, Pierre

2015-10-07

We present a general and straightforward one-step approach to enhance the photophysical properties of conjugated polyelectrolytes. Upon complexation with an amphiphilic polymer (polyvinylpyrrolidone), an anionic conjugated polyelectrolyte (poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene]) was prepared into small nanoparticles with exceptional photostability and brightness. The polymer fluorescence intensity was enhanced by 23 -fold and could be easily tuned by changing the order of addition. Single molecule experiments revealed a complete suppression of blinking. In addition, after only losing 18% of the original intensity, a remarkable amount of photons were emitted per particle (∼10(9), on average). This number is many folds greater than popular organic fluorescent dyes. We believe that an intimate contact between the two polymers is shielding the conjugated polyelectrolyte from the destructive photooxidation. The prepared nanohybrid particles will prove instrumental in single particle based fluorescent assays and can serve as a probe for the current state-of-the-art bioimaging fluorescence techniques.

Diketopyrrolopyrrole Polymers for Organic Solar Cells.

PubMed

Li, Weiwei; Hendriks, Koen H; Wienk, Martijn M; Janssen, René A J

2016-01-19

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 result, the power conversion efficiencies (PCEs) of solar cells based on conjugated polymers as electron donor and fullerene derivatives as electron acceptor have exceeded 10% in single-junction and 11% in multijunction devices. Despite these efforts, it is notoriously difficult to establish thorough structure-property relationships that will be required to further optimize existing high-performance polymers to their intrinsic limits. In this Account, we highlight progress on the development and our understanding of diketopyrrolopyrrole (DPP) based conjugated polymers for polymer solar cells. The DPP moiety is strongly electron withdrawing and its polar nature enhances the tendency of DPP-based polymers to crystallize. As a result, DPP-based conjugated polymers often exhibit an advantageously broad and tunable optical absorption, up to 1000 nm, and high mobilities for holes and electrons, which can result in high photocurrents and good fill factors in solar cells. Here we focus on the structural modifications applied to DPP polymers and rationalize and explain the relationships between chemical structure and organic photovoltaic performance. The DPP polymers can be tuned via their aromatic substituents, their alkyl side chains, and the nature of the π-conjugated segment linking the units along the polymer chain. We show that these building blocks work together in determining the molecular conformation, the optical properties, the charge carrier mobility, and the solubility of the polymer. We identify the latter as a decisive parameter for DPP-based organic solar cells because it regulates the diameter of the semicrystalline DPP polymer fibers that form in the photovoltaic blends with fullerenes via solution processing. The width of these fibers and the photon energy loss, defined as the energy difference between optical band gap and open-circuit voltage, together govern to a large extent the quantum efficiency for charge generation in these blends and thereby the power conversion efficiency of the photovoltaic devices. Lowering the photon energy loss and maintaining a high quantum yield for charge generation is identified as a major pathway to enhance the performance of organic solar cells. This can be achieved by controlling the structural purity of the materials and further control over morphology formation. We hope that this Account contributes to improved design strategies of DPP polymers that are required to realize new breakthroughs in organic solar cell performance in the future.

Peptides, proteins and peptide/protein-polymer conjugates as drug delivery system.

PubMed

Mukherjee, Biswajit; Karmakar, Swapna D; Hossain, Chowdhury M; Bhattacharya, Sanchari

2014-01-01

In the last few decades, novel drug delivery strategies have been a big priority to the formulation scientists. Peptides and proteins have drawn a special attention for their wide scope in the area. Serum albumin, transferrin, recom- binant proteins, virus capsids etc. are used as carrier for drug and biomolecules. Conjugates of polymers with proteins have also shown strong potency in the field of drug delivery. Polyethylene glycol is one of the most successful polymers that has been used extensively to develop protein conjugated formulations. Besides, polyvinyl pyrrolidone, polylactic-co- glycolic acid, N-(2-hydroxypropyl) methacrylamide copolymer, polyglutamic acid have also been investigated. In this re- view, we will highlight on the most recent overview of various advantages, limitations and marketed products of proteins, peptides and protein/peptide-polymer conjugates as drug carriers, such products in clinical trials and their various uses in the field of modern drug delivery. Understanding the key features of these materials and the vigorous research in this field will develop new drug formulations that will combat various types of life-threatening diseases.

Enhanced Reciprocal Interactions between Molecular Stresses and Optoelectronic Energy Transfers for High Efficiency Long Life Devices Based on Conjugated Polymers

DTIC Science & Technology

2014-10-15

led to lower PL efficiencies. The latter, however, posed no problems for solar cells aplications . Furthermore, the molecular dipoles composed of...illuminated under the light of the energy falling in the absorption range of the conjugated polymer, the polymer chain mobility decreased...the other hand, increased concomitantly (Figs. 33, 35). The driving force for the molecular flows is the diffusion of the mobile PS chains toward

Targeted conjugation of breast anticancer drug tamoxifen and its metabolites with synthetic polymers.

PubMed

Sanyakamdhorn, S; Agudelo, D; Bekale, L; Tajmir-Riahi, H A

2016-09-01

Conjugation of antitumor drug tamoxifen and its metabolites, 4-hydroxytamxifen and ednoxifen with synthetic polymers poly(ethylene glycol) (PEG), methoxypoly (ethylene glycol) polyamidoamine (mPEG-PAMAM-G3) and polyamidoamine (PAMAM-G4) dendrimers was studied in aqueous solution at pH 7.4. Multiple spectroscopic methods, transmission electron microscopy (TEM) and molecular modeling were used to characterize the drug binding process to synthetic polymers. Structural analysis showed that drug-polymer binding occurs via both H-bonding and hydrophobic contacts. The order of binding is PAMAM-G4>mPEG-PAMAM-G3>PEG-6000 with 4-hydroxttamoxifen forming more stable conjugate than tamoxifen and endoxifen. Transmission electron microscopy showed significant changes in carrier morphology with major changes in the shape of the polymer aggregate as drug encapsulation occurred. Modeling also showed that drug is located in the surface and in the internal cavities of PAMAM with the free binding energy of -3.79 for tamoxifen, -3.70 for 4-hydroxytamoxifen and -3.69kcal/mol for endoxifen, indicating of spontaneous drug-polymer interaction at room temperature. Copyright © 2016 Elsevier B.V. All rights reserved.

Extension of in vivo half-life of biologically active peptides via chemical conjugation to XTEN protein polymer.

PubMed

Podust, Vladimir N; Sim, Bee-Cheng; Kothari, Dharti; Henthorn, Lana; Gu, Chen; Wang, Chia-wei; McLaughlin, Bryant; Schellenberger, Volker

2013-11-01

XTEN, unstructured biodegradable proteins, have been used to extend the in vivo half-life of genetically fused therapeutic proteins and peptides. To expand the applications of XTEN technology to half-life extension of other classes of molecules, XTEN protein polymers and methods for chemical XTENylation were developed. Two XTEN precursors were engineered to contain enzymatically removable purification tags. The proteins were readily expressed in bacteria and purified to homogeneity by chromatography techniques. As proof-of-principle, GLP2-2G peptide was chemically conjugated to each of the two XTEN protein polymers using maleimide-thiol chemistry. The monodisperse nature of XTEN protein polymer enabled reaction monitoring as well as the detection of peptide modifications in the conjugated state using reverse phase-high performance liquid chromatography (RP-HPLC) and electrospray ionization mass spectrometry. The resulting GLP2-2G-XTEN conjugates were purified by preparative RP-HPLC to homogeneity. In comparison with recombinantly fused GLP2-2G-XTEN, chemically conjugated GLP2-2G-XTEN molecules exhibited comparable in vitro activity, in vitro plasma stability and pharmacokinetics in rats. These data suggest that chemical XTENylation could effectively extend the half-life of a wide spectrum of biologically active molecules, therefore broadening its applicability.

In Vivo Anticancer Efficacy and Toxicity Studies of a Novel Polymer Conjugate N-Acetyl Glucosamine (NAG)-PEG-Doxorubicin for Targeted Cancer Therapy.

PubMed

Pawar, Smita; Mahajan, Ketan; Vavia, Pradeep

2017-11-01

A novel polymer-drug conjugate, polyethylene glycol-N-(acetyl)-glucosamine-doxorubicin (PEG-NAG-DOX) was evaluated in this study for its in vivo potential for treatment of tumours demonstrating improved efficacy and reduced toxicity. The proposed polymer-drug conjugate comprised of polyethylene glycol-maleimide (mPEG-MAL, 30000 Da) as a carrier, doxorubicin (DOX) as an anticancer drug and N-acetyl glucosamine (NAG) as a targeting moiety as well as penetration enhancer. Doxorubicin has a potent and promising anticancer activity; however, severe cardiotoxicity limits its application in cancer treatment. By modifying DOX in PEG-NAG-DOX prodrug conjugate, we aimed to eliminate this limitation. In vivo anticancer efficacy of the conjugate was evaluated using BDF mice-induced skin melanoma model by i.v. administration of DOX conjugates. Anticancer efficacy studies were done by comparing tumour volume, body weight, organ index and percent survival rate of the animals. Tumour suppression achieved by PEG-NAG-DOX at the cumulative dose of 7.5 mg/kg was two-fold better than that achieved by DOX solution. Also, the survival rate for PEG-NAG-DOX conjugate was >70% as compared to <50% survival rate for DOX solution. In addition, toxicity studies and histopathological studies revealed that while maintaining its cytotoxicity towards tumour cells, PEG-NAG-DOX conjugate showed no toxicities to major organs. Therefore, PEG-NAG-DOX conjugate can be suggested as a desirable candidate for targeted cancer therapy.

Controlling photophysical properties of ultrasmall conjugated polymer nanoparticles through polymer chain packing

PubMed Central

Piwoński, Hubert; Michinobu, Tsuyoshi; Habuchi, Satoshi

2017-01-01

Applications of conjugated polymer nanoparticles (Pdots) for imaging and sensing depend on their size, fluorescence brightness and intraparticle energy transfer. The molecular design of conjugated polymers (CPs) has been the main focus of the development of Pdots. Here we demonstrate that proper control of the physical interactions between the chains is as critical as the molecular design. The unique design of twisted CPs and fine-tuning of the reprecipitation conditions allow us to fabricate ultrasmall (3.0–4.5 nm) Pdots with excellent photostability. Extensive photophysical and structural characterization reveals the essential role played by the packing of the polymer chains in the particles in the intraparticle spatial alignment of the emitting sites, which regulate the fluorescence brightness and the intraparticle energy migration efficiency. Our findings enhance understanding of the relationship between chain interactions and the photophysical properties of CP nanomaterials, providing a framework for designing and fabricating functional Pdots for imaging applications. PMID:28508857

Surface chemistry of photoluminescent F8BT conjugated polymer nanoparticles determines protein corona formation and internalization by phagocytic cells.

PubMed

Ahmad Khanbeigi, Raha; Abelha, Thais Fedatto; Woods, Arcadia; Rastoin, Olivia; Harvey, Richard D; Jones, Marie-Christine; Forbes, Ben; Green, Mark A; Collins, Helen; Dailey, Lea Ann

2015-03-09

Conjugated polymer nanoparticles are being developed for a variety of diagnostic and theranostic applications. The conjugated polymer, F8BT, a polyfluorene derivative, was used as a model system to examine the biological behavior of conjugated polymer nanoparticle formulations stabilized with ionic (sodium dodecyl sulfate; F8BT-SDS; ∼207 nm; -31 mV) and nonionic (pegylated 12-hydroxystearate; F8BT-PEG; ∼175 nm; -5 mV) surfactants, and compared with polystyrene nanoparticles of a similar size (PS200; ∼217 nm; -40 mV). F8BT nanoparticles were as hydrophobic as PS200 (hydrophobic interaction chromatography index value: 0.96) and showed evidence of protein corona formation after incubation with serum-containing medium; however, unlike polystyrene, F8BT nanoparticles did not enrich specific proteins onto the nanoparticle surface. J774A.1 macrophage cells internalized approximately ∼20% and ∼60% of the F8BT-SDS and PS200 delivered dose (calculated by the ISDD model) in serum-supplemented and serum-free conditions, respectively, while cell association of F8BT-PEG was minimal (<5% of the delivered dose). F8BT-PEG, however, was more cytotoxic (IC50 4.5 μg cm(-2)) than F8BT-SDS or PS200. The study results highlight that F8BT surface chemistry influences the composition of the protein corona, while the properties of the conjugated polymer nanoparticle surfactant stabilizer used determine particle internalization and biocompatibility profile.

In-situ fabrication of diketopyrrolopyrrole-carbazole-based conjugated polymer/TiO2 heterojunction for enhanced visible light photocatalysis

NASA Astrophysics Data System (ADS)

Yang, Long; Yu, Yuyan; Zhang, Jianling; Chen, Fu; Meng, Xiao; Qiu, Yong; Dan, Yi; Jiang, Long

2018-03-01

Aiming at developing highly efficient photocatalysts by broadening the light-harvesting region and suppressing photo-generated electron-hole recombination simultaneously, this work reports rational design and fabrication of donor-acceptor (D-A) conjugated polymer/TiO2 heterojunction catalyst with strong interfacial interactions by a facile in-situ thermal treatment. To expand the light-harvesting window, soluable conjugated copolymers with D-A architecture are prepared by Pd-mediated polycondensation of diketopyrrolopyrrole (DPP) and t-butoxycarbonyl (t-Boc) modified carbazole (Car), and used as visible-light-harvesting antenna to couple with TiO2 nanocrystals. The DPP-Car/TiO2 composites show wide range absorption in 300-1000 nm. To improve the interfacial binding at the interface, a facile in-situ thermal treatment is carried out to cleave the pendant t-Boc groups in carbazole units and liberate the polar amino groups (-NH-) which strongly bind to the surface of TiO2 through dipole-dipole interactions, forming a heterojunction interface. This in-situ thermal treatment changes the surface elemental distribution of TiO2, reinforces the interface bonding at the boundary of conjugated polymers/TiO2 and finally improves the photocatalytic efficiency of DPP-Car/TiO2 under visible-light irradiation. The interface changes are characterized and verified through Fourier-transform infrared spectroscopy (FT-IR), photo images, UV/Vis (solution state and powder diffuse reflection spectroscopy), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fluorescence, scanning electron microscopy(SEM) and transmission electron microscopy (TEM) techniques. This study provides a new strategy to avoid the low solubility of D-A conjugated polymers and construct highly-efficient conjugated polymer/TiO2 heterojunction by enforcing the interface contact and facilitating charge or energy transfer for the applications in photocatalysis.

Nanohybrid conjugated polyelectrolytes: highly photostable and ultrabright nanoparticles

NASA Astrophysics Data System (ADS)

Darwish, Ghinwa H.; Karam, Pierre

2015-09-01

We present a general and straightforward one-step approach to enhance the photophysical properties of conjugated polyelectrolytes. Upon complexation with an amphiphilic polymer (polyvinylpyrrolidone), an anionic conjugated polyelectrolyte (poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene]) was prepared into small nanoparticles with exceptional photostability and brightness. The polymer fluorescence intensity was enhanced by 23 -fold and could be easily tuned by changing the order of addition. Single molecule experiments revealed a complete suppression of blinking. In addition, after only losing 18% of the original intensity, a remarkable amount of photons were emitted per particle (~109, on average). This number is many folds greater than popular organic fluorescent dyes. We believe that an intimate contact between the two polymers is shielding the conjugated polyelectrolyte from the destructive photooxidation. The prepared nanohybrid particles will prove instrumental in single particle based fluorescent assays and can serve as a probe for the current state-of-the-art bioimaging fluorescence techniques.We present a general and straightforward one-step approach to enhance the photophysical properties of conjugated polyelectrolytes. Upon complexation with an amphiphilic polymer (polyvinylpyrrolidone), an anionic conjugated polyelectrolyte (poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene]) was prepared into small nanoparticles with exceptional photostability and brightness. The polymer fluorescence intensity was enhanced by 23 -fold and could be easily tuned by changing the order of addition. Single molecule experiments revealed a complete suppression of blinking. In addition, after only losing 18% of the original intensity, a remarkable amount of photons were emitted per particle (~109, on average). This number is many folds greater than popular organic fluorescent dyes. We believe that an intimate contact between the two polymers is shielding the conjugated polyelectrolyte from the destructive photooxidation. The prepared nanohybrid particles will prove instrumental in single particle based fluorescent assays and can serve as a probe for the current state-of-the-art bioimaging fluorescence techniques. Electronic supplementary information (ESI) available: Dynamic light scattering, photostability of different nanohybrids, and emission and absorption spectra. See DOI: 10.1039/c5nr03299g

Photophysics of single-walled carbon nanotubes: similarity with π-conjugated polymer

NASA Astrophysics Data System (ADS)

Zhao, Hongbo

2006-03-01

Coulomb electron-electron (e-e) interactions among the π-electrons have a strong effect on the energy spectra of semiconducting single-walled carbon nanotubes (S-SWCNTs), because of their quasi-one-dimensionality. The primary photoexcitations in S-SWCNTs as a consequence of e-e interactions are excitons, as opposed to free electrons and holes. There already exists a vast literature on excitons in π-conjugated polymers, the other class of carbon-based quasi-one-dimensional semiconductors. In order to seek guidance from this knowledge base, we have performed theoretical calculations of the excited state electronic structures, linear absorptions and excited state absorptions for ten different S-SWCNTs with a wide range in diameters, within the same correlated π-electron model that has previously been applied to π-conjugated polymers. We found remarkable similarities in the excitonic energy spectra and nonlinear optical properties of S-SWCNTs on the one hand, and π-conjugated polymers on the other. The ``essential states'' model of third-order optical nonlinearity, previously developed for π-conjugated polymers, applies also to S-SWCNTs (with minor modifications for chiral S-SWCNTs which lack center of inversion). Our theory is able to explain semiquantitatively the results of nonlinear spectroscopic measurements on both S-SWCNTs and π-conjugated polymers. For wide S-SWCNTs with diameters ranging from 0.8--1.0 nm, we calculate exciton binding energies of 0.3--0.4 eV, in strong agreement with the values predicted from the experiments. We also remark on the occurrence of dark excitons below the optical excitons in the S-SWCNTs, and the consequence thereof on the photoluminescence of these materials. H. Zhao, et al., cond-mat/0506097; J. W. Kennedy, et al., cond-mat/0505071. S. N. Dixit, D. Guo, and S. Mazumdar, Phys. Rev. B 43, R6781 (1991) H. Zhao and S. Mazumdar, Phys. Rev. Lett. 93, 157402 (2004).

Truxene-Based Hyperbranched Conjugated Polymers: Fluorescent Micelles Detect Explosives in Water.

PubMed

Huang, Wei; Smarsly, Emanuel; Han, Jinsong; Bender, Markus; Seehafer, Kai; Wacker, Irene; Schröder, Rasmus R; Bunz, Uwe H F

2017-01-25

We report two hyperbranched conjugated polymers (HCP) with truxene units as core and 1,4-didodecyl-2,5-diethynylbenzene as well as 1,4-bis(dodecyloxy)-2,5-diethynylbenzene as comonomers. Two analogous poly(para-phenyleneethynylene)s (PPE) are also prepared as comparison to demonstrate the difference between the truxene and the phenyl moieties in their optical properties and their sensing performance. The four polymers are tested for nitroaromatic analytes and display different fluorescence quenching responses. The quenching efficiencies are dependent upon the spectral overlap between the absorbance of the analyte and the emission of the fluorescent polymer. Optical fingerprints are obtained, based on the unique response patterns of the analytes toward the polymers. With this small sensor array, one can distinguish nine nitroaromatic analytes with 100% accuracy. The amphiphilic polymer F127 (a polyethylene glycol-polypropylene glycol block copolymer) carries the hydrophobic HCPs and self-assembles into micelles in water, forming highly fluorescent HCP micelles. The micelle-bound conjugated polymers detect nitroaromatic analytes effectively in water and show an increased sensitivity compared to the sensing of nitroaromatics in organic solvents. The nitroarenes are also discriminated in water using this four-element chemical tongue.

Synthesis and evaluation of polymers for use in early warning fire alarm devices

NASA Technical Reports Server (NTRS)

Byrd, N. R.; Sheratte, M. B.

1975-01-01

Conjugated polyacetylene polymers and one condensation polyene, all containing a high degree of conjugated unsaturation, were synthesized. These polymers were characterized by chemical analysis and by thermogravimetric analysis, as well as for their film-forming capability and gas/polymer interactions. It was found that those that had a high degree of conjugated unsaturation and had resonance - stabilizing groups were very thermally stable to 200 C, e.g., poly(dicyanoacetylene), poly(ethynylferrocene) and poly(phenylacetylene); while those with labile moieties, such as poly(p-formamidophenylacetylene), among others, suffered some degradation when heated in air. When subjected to gas/polymer interaction effects, the greatest change in electrical conductance was observed when ammonia was used as the gas and poly(p-nitrophenylacetylene) was the detector. Other polymers showed similar behavior. For example, poly(ethynylcarborane), considered to be an electron acceptor also showed a change in electrical conductance when exposed to ammonia, while poly(ethynylpyridine) and poly(ethylidenepyridazine) responded to carbon monoxide. However, for "fire gases" (gases from smoldering cotton), poly(ethynylferrocene) was the most responsive. Thus, the concept of polymers with different electronegativities forming charge-transfer complexes with different gases was found to be operable.

Bactericidal Specificity and Resistance Profile of Poly(Quaternary Ammonium) Polymers and Protein-Poly(Quaternary Ammonium) Conjugates.

PubMed

Ji, Weihang; Koepsel, Richard R; Murata, Hironobu; Zadan, Sawyer; Campbell, Alan S; Russell, Alan J

2017-08-14

Antibacterial polymers are potentially powerful biocides that can destroy bacteria on contact. Debate in the literature has surrounded the mechanism of action of polymeric biocides and the propensity for bacteria to develop resistance to them. There has been particular interest in whether surfaces with covalently coupled polymeric biocides have the same mechanism of action and resistance profile as similar soluble polymeric biocides. We designed and synthesized a series of poly(quaternary ammonium) polymers, with tailorable molecular structures and architectures, to engineer their antibacterial specificity and their ability to delay the development of bacterial resistance. These linear poly(quaternary ammonium) homopolymers and block copolymers, generated using atom transfer radical polymerization, had structure-dependent antibacterial specificity toward Gram positive and negative bacterial species. When single block copolymers contained two polymer segments of differing antibacterial specificity, the polymer combined the specificities of its two components. Nanoparticulate human serum albumin-poly(quaternary ammonium) conjugates of these same polymers, synthesized via "grafting from" atom transfer radical polymerization, were strongly biocidal and also exhibited a marked decrease in the rate of bacterial resistance development relative to linear polymers. These protein-biocide conjugates mimicked the behavior of surface-presented polycationic biocides rather than their nonproteinaceous counterparts.

Synthesis of highly water-soluble fluorescent conjugated glycopoly(p-phenylene)s for lectin and Escherichia coli.

PubMed

Xue, Cuihua; Jog, Sonali P; Murthy, Pushpalatha; Liu, Haiying

2006-09-01

Two facile, convenient, and versatile synthetic approaches are used to covalently attach carbohydrate residues to conjugated poly(p-phenylene)s (PPPs) for highly water-soluble PPPs bearing alpha-mannopyranosyl and beta-glucopyranosyl pendants (polymers A and B), which highly fluoresce in phosphate buffer (pH 7.0). The post-polymerization functionalization approach is to treat bromo-bearing PPP (polymer 1) with 1-thiolethyl-alpha-D-mannose tetraacetate or 1-thiol-beta-D-glucose tetraacetate in THF solution in the presence of K(2)CO(3) at room temperature through formation of thioether bridges, affording polymer 2a or 2b. The prepolymerization functionalization approach is to polymerize a well-defined sugar-carrying monomer, affording polymer 2a. Polymers 2a and 2b were deacetylated under Zemplén conditions in methanol and methylene chloride containing sodium methoxide, affording polymers A and B, respectively. The multivalent display of carbohydrates on the fluorescent conjugated glycopolymer overcomes the characteristic low binding affinity of the individual carbohydrates to their receptor proteins. Titration of concanavalin A (Con A) to alpha-mannose-bearing polymer A resulted in significant fluorescent quenching of the polymer with Stern-Volmer quenching constant of 4.5 x 10(7). Incubation of polymer A with Escherichia coli (E. coli) lead to formation of fluorescently stained bacterial clusters. Beta-glucose-bearing polymer B displayed no response to Con A and E. coli.

Molecular weight dependent structure and charge transport in MAPLE-deposited poly(3-hexylthiophene) thin films

DOE PAGES

Dong, Ban Xuan; Smith, Mitchell; Strzalka, Joseph; ...

2018-02-06

In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less

Molecular weight dependent structure and charge transport in MAPLE-deposited poly(3-hexylthiophene) thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Ban Xuan; Smith, Mitchell; Strzalka, Joseph

In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less

Chemical oxidative and solid state synthesis of low molecular weight polymers for organic field effect transistors

NASA Astrophysics Data System (ADS)

Mahale, Rajashree Y.; Dharmapurikar, Satej S.; Chini, Mrinmoy Kumar

2018-03-01

Solution processability of the precursor molecules is a major issue owing to their limited solubility for the synthesis of conjugated polymers. Therefore, we favour the solvent free solid state chemical oxidative polymerization route for the synthesis of diketopyrrolopyrrole (DPP) based donor-acceptor (D-A) type conjugated polymers. D-A type polymer Poly(S-OD-EDOT) which contains DPP coupled with EDOT donor units is synthesized via solid state polymerization method. The polymer is employed as an active layer for organic field-effect transistors to measure charge transport properties. The Polymer shows good hole mobility 3.1 × 10-2 cm2 V-1 s-1, with a on/off ratio of 1.1 × 103.

Neutral Polymer Micelle Carriers with pH-Responsive, Endosome-Releasing Activity Modulate Antigen Trafficking to Enhance CD8 T-Cell Responses

PubMed Central

Keller, Salka; Wilson, John T; Patilea, Gabriela I; Kern, Hanna B; Convertine, Anthony J; Stayton, Patrick S

2014-01-01

Synthetic subunit vaccines need to induce CD8+ cytotoxic T-cell (CTL) responses for effective vaccination against intracellular pathogens. Most subunit vaccines primarily generate humoral immune responses, with a weaker than desired CD8+ cytotoxic T-cell response. Here, a neutral, pH-responsive polymer micelle carrier that alters intracellular antigen trafficking was shown to enhance CD8+ T-cell responses with a correlated increase in cytosolic delivery and a decrease in exocytosis. Polymer diblock carriers consisted of a N-(2-hydroxypropyl) methacrylamide corona block with pendant pyridyl disulfide groups for reversible conjugation of thiolated ovalbumin, and a tercopolymer ampholytic core-forming block composed of propylacrylic acid (PAA), dimethylaminoethyl methacrylate (DMAEMA), and butyl methacrylate (BMA). The diblock copolymers self-assembled into 25–30 nm diameter micellar nanoparticles. Conjugation of ovalbumin to the micelles significantly enhanced antigen cross-presentation in vitro relative to free ovalbumin, an unconjugated physical mixture of ovalbumin and polymer, and a non pH-responsive micelle-ovalbumin control. Mechanistic studies in a murine dendritic cell line (DC2.4) demonstrated micelle-mediated enhancements in intracellular antigen retention and cytosolic antigen accumulation. Approximately 90% of initially internalized ovalbumin-conjugated micelles were retained in cells after 1.5 h, compared to only ~40% for controls. Furthermore, cells dosed with conjugates displayed 67-fold higher cytosolic antigen levels relative to soluble ovalbumin 4 h post uptake. Subcutaneous immunization of mice with ovalbumin-polymer conjugates significantly enhanced antigen-specific CD8+ T cell responses (0.4 % IFN-γ+ of CD8+) compared to immunization with soluble protein, ovalbumin and polymer mixture, and the control micelle without endosome-releasing activity. Additionally, pH-responsive carrier facilitated antigen delivery to antigen presenting cells in the draining lymph nodes. As early as 90 min post injection ova-micelle conjugates were associated with 28% and 55% of dendritic cells and macrophages, respectively. After 24 h, conjugates preferentially associated with dendritic cells, affording 30-, 3-, and 3-fold enhancements in uptake relative to free protein, physical mixture, and the non pH-responsive conjugate controls, respectively. These results demonstrate the potential of pH-responsive polymeric micelles for use in vaccine applications that rely on CD8+ T cell activation. PMID:24698946

Neutral polymer micelle carriers with pH-responsive, endosome-releasing activity modulate antigen trafficking to enhance CD8(+) T cell responses.

PubMed

Keller, Salka; Wilson, John T; Patilea, Gabriela I; Kern, Hanna B; Convertine, Anthony J; Stayton, Patrick S

2014-10-10

Synthetic subunit vaccines need to induce CD8(+) cytotoxic T cell (CTL) responses for effective vaccination against intracellular pathogens. Most subunit vaccines primarily generate humoral immune responses, with a weaker than desired CD8(+) cytotoxic T cell response. Here, a neutral, pH-responsive polymer micelle carrier that alters intracellular antigen trafficking was shown to enhance CD8(+) T cell responses with a correlated increase in cytosolic delivery and a decrease in exocytosis. Polymer diblock carriers consisted of a N-(2-hydroxypropyl) methacrylamide corona block with pendent pyridyl disulfide groups for reversible conjugation of thiolated ovalbumin, and a tercopolymer ampholytic core-forming block composed of propylacrylic acid (PAA), dimethylaminoethyl methacrylate (DMAEMA), and butyl methacrylate (BMA). The diblock copolymers self-assembled into 25-30nm diameter micellar nanoparticles. Conjugation of ovalbumin to the micelles significantly enhanced antigen cross-presentation in vitro relative to free ovalbumin, an unconjugated physical mixture of ovalbumin and polymer, and a non-pH-responsive micelle-ovalbumin control. Mechanistic studies in a murine dendritic cell line (DC 2.4) demonstrated micelle-mediated enhancements in intracellular antigen retention and cytosolic antigen accumulation. Approximately 90% of initially internalized ovalbumin-conjugated micelles were retained in cells after 1.5h, compared to only ~40% for controls. Furthermore, cells dosed with conjugates displayed 67-fold higher cytosolic antigen levels relative to soluble ovalbumin 4h post uptake. Subcutaneous immunization of mice with ovalbumin-polymer conjugates significantly enhanced antigen-specific CD8(+) T cell responses (0.4% IFN-γ(+) of CD8(+)) compared to immunization with soluble protein, ovalbumin and polymer mixture, and the control micelle without endosome-releasing activity. Additionally, pH-responsive carrier facilitated antigen delivery to antigen presenting cells in the draining lymph nodes. As early as 90min post injection, ova-micelle conjugates were associated with 28% and 55% of dendritic cells and macrophages, respectively. After 24h, conjugates preferentially associated with dendritic cells, affording 30-, 3-, and 3-fold enhancements in uptake relative to free protein, physical mixture, and the non-pH-responsive conjugate controls, respectively. These results demonstrate the potential of pH-responsive polymeric micelles for use in vaccine applications that rely on CD8(+) T cell activation. Copyright © 2014 Elsevier B.V. All rights reserved.

Spatial-temporal light modulation by a liquid crystal-polymer photoconductor structure with conjugate bonds

NASA Astrophysics Data System (ADS)

Sliusar', A. V.; Myl'Nikov, V. S.

1991-11-01

A method is proposed for the spatial-temporal modulation of light by a polymer photoconductor-liquid crystal structure using conjugate-bond organic polymers as photosensitive elements. The preparation of such structures and their modulation characteristics are described. It is shown that the spectral absorption and photosensitivity characteristics of the structures are largely determined by the heat treament of the polymer film. Sensitivity limits of a modulator using a polyacrylonitrile film are 5 x 10 exp -6 J/sq cm and 5 x 10 exp -4 W/sq cm for the write and read light, respectively.

Water-soluble cationic conjugated polymers: response to electron-rich bioanalytes.

PubMed

Rochat, Sébastien; Swager, Timothy M

2013-11-27

We report the concise synthesis of a symmetrical monomer that provides a head-to-head pyridine building block for the preparation of cationic conjugated polymers. The obtained poly(pyridinium-phenylene) polymers display appealing properties such as high electron affinity, charge-transport upon n-doping, and optical response to electron-donating analytes. A simple assay for the optical detection of low micromolar amounts of a variety of analytes in aqueous solution was developed. In particular, caffeine could be measured at a 25 μM detection limit. The reported polymers are also suitable for layer-by-layer film formation.

Neighbor effect in complexation of a conjugated polymer.

PubMed

Sosorev, Andrey; Zapunidi, Sergey

2013-09-19

Charge-transfer complex (CTC) formation between a conjugated polymer and low-molecular-weight organic acceptor is proposed to be driven by the neighbor effect. Formation of a CTC on the polymer chain results in an increased probability of new CTC formation near the existing one. We present an analytical model for CTC distribution considering the neighbor effect, based on the principles of statistical mechanics. This model explains the experimentally observed threshold-like dependence of the CTC concentration on the acceptor content in a polymer:acceptor blend. It also allows us to evaluate binding energies of the complexes.

Plastic Electronics and Optoelectronics: New Science and Technology from Soluble Semiconducting Polymers and Bulk Heterojunction Solar Cells Fabricated from Soluble Semiconducting Polymers

DTIC Science & Technology

2011-11-03

fundamental discovery of photoinduced ultrafast electron transfer from conjugated polymers to fullerenes . Many groups in the U.S., Europe and Asia are...electron transfer from conjugated polymers to fullerenes . Many groups in the U.S., Europe and Asia are now making important contributions. Nevertheless...This confirms that the middle curve in Fig. 1 utilizes the correct assumptions.          2ln 1 c heBPolymer HOMO Fullerene LUMOoc N

Synthesis of conjugated chitosan and its effect on drug permeation from transdermal patches.

PubMed

Satheeshababu, B K; Shivakumar, K L

2013-03-01

The aim of this study was to synthesis the conjugated chitosan by covalent attachment of thiol moieties to the cationic polymer, mediated by a carbodiimide to improve permeation properties of chitosan. Thioglycolic acid was covalently attached to chitosan by the formation of amide bonds between the primary amino groups of the polymer and the carboxylic acid groups of thioglycolic acid. Hence, these polymers are called as thiomers or thiolated polymers. Conjugation of chitosan was confirmed by Fourier transform-infrared and differential scanning calorimetric analysis. Matrix type transdermal patches of carvedilol were prepared using the different proportions of chitosan and chitosan-thioglycolic acid conjugates (2:0, 1.7:0.3, 1.4:0.6, 1:1, 0.6:1.4 and 0.3:1.7) by solvent casting technique. Prepared matrix type patches were evaluated for their physicochemical characterization followed by in vitro evaluation. Selected formulations were subjected for their ex vivo studies on Wistar albino rat skin and human cadaver skin using the modified Franz diffusion cell. As the proportion of conjugated chitosan increased, the transdermal patches showed increased drug permeation. The mechanism of drug release was found to be nonFickian profiles. The present study concludes that the transdermal patches of carvedilol using conjugated chitosan with different proportions of chitosan were successfully developed to provide improved drug permeation. The transdermal patches can be a good approach to improve drug bioavailability by bypassing the extensive hepatic first-pass metabolism of the drug.

Resonant Raman scattering of controlled molecular weight polyacetylene

NASA Astrophysics Data System (ADS)

Schen, M. A.; Chien, J. C. W.; Perrin, E.; Lefrant, S.; Mulazzi, E.

1988-12-01

Polyacetylene, (CH)x, films of 500, 5300, 10 500, and 100 000 Daltons number average molecular weights (Mn ) were synthesized using the titanium tetra-n-butoxide/triethyl aluminum-catalyst/cocatalyst system and examined using resonant Raman scattering techniques. Before isomerization, trans segments are found to exist mainly as short, isolated sequences independent of Mn. After thermal isomerization, theoretical analysis of the RRS spectra using the Brivio, Mulazzi model indicate the ratio of long trans conjugated segments (N≥30) to short trans conjugated segments (N≤30) is significantly larger for 100 000 Dalton polymer in comparison to polymer of 10 500 Mn and below. For samples below 10 500 Daltons, no clear relationship between actual polymer molecular weight and G is observed. Optimization of the isomerization conditions for 100 000 Dalton polymer results in trans-(CH)x with a G=0.80. These results suggest that not until very long molecular chains are obtained can samples composed principally of long conjugated segments be obtained. It is proposed that defects which arise during and after the polymerization limit the content of long segments. Ambient, short term oxidation of 100 000 Mn polymer shows a decrease in G from 0.80 to 0.70. Low level chain oxidation or doping is shown to preferentially occur within long conjugated segments.

Naphtho[1,2-b:5,6-b']dithiophene-Based Conjugated Polymers for Fullerene-Free Inverted Polymer Solar Cells.

PubMed

Jiang, Zhaoyan; Li, Huan; Wang, Zhen; Zhang, Jianqi; Zhang, Yajie; Lu, Kun; Wei, Zhixiang

2018-03-23

Three novel copolymers based on zigzag naphthodithiophene (zNDT) with different aromatic rings as π bridges and different core side substitutions are designed and synthesized (PzNDT-T-1,3-bis(4-(2-ethylhexyl)-thiophen-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c']-dithiophene-4,8-dione (BDD), PzNDT-TT-BDD, and PzNDTP-T-BDD, respectively). The 2D conjugation structure and molecular planarity of the polymers can be effectively altered through the modification of conjugated side chains and π-bridges. These alterations contribute to the variation in energy levels, light absorption capacity, and morphology compatibility of the polymers. When blended with the nonfullerene acceptor (2,2'-[(4,4,9,9-tetrahexyl-4,9-dihydro-sindaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis[methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)

Understanding Peptide Oligomeric State in Langmuir Monolayers of Amphiphilic 3-Helix Bundle-Forming Peptide-PEG Conjugates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lund, Reidar; Ang, JooChuan; Shu, Jessica Y.

Coiled-coil peptide-polymer conjugates are an emerging class of biomaterials. Fundamental understanding of the coiled-coil oligomeric state and assembly process of these hybrid building blocks is necessary to exert control over their assembly into well-defined structures. Here in this paper, we studied the effect of peptide structure and PEGylation on the self-assembly process and oligomeric state of a Langmuir monolayer of amphiphilic coiled-coil peptide-polymer conjugates using X-ray reflectivity (XR) and grazing-incidence X-ray diffraction (GIXD). Our results show that the oligomeric state of PEGylated amphiphiles based on 3-helix bundle-forming peptide is surface pressure dependent, a mixture of dimers and trimers was formedmore » at intermediate surface pressure but transitions into trimers completely upon increasing surface pressure. Moreover, the interhelical distance within the coiled-coil bundle of 3-helix peptide-PEG conjugate amphiphiles was not perturbed under high surface pressure. Present studies provide valuable insights into the self-assembly process of hybrid peptide-polymer conjugates and guidance to develop biomaterials with controlled multivalency of ligand presentation.« less

Understanding Peptide Oligomeric State in Langmuir Monolayers of Amphiphilic 3-Helix Bundle-Forming Peptide-PEG Conjugates

DOE PAGES

Lund, Reidar; Ang, JooChuan; Shu, Jessica Y.; ...

2016-10-26

Coiled-coil peptide-polymer conjugates are an emerging class of biomaterials. Fundamental understanding of the coiled-coil oligomeric state and assembly process of these hybrid building blocks is necessary to exert control over their assembly into well-defined structures. Here in this paper, we studied the effect of peptide structure and PEGylation on the self-assembly process and oligomeric state of a Langmuir monolayer of amphiphilic coiled-coil peptide-polymer conjugates using X-ray reflectivity (XR) and grazing-incidence X-ray diffraction (GIXD). Our results show that the oligomeric state of PEGylated amphiphiles based on 3-helix bundle-forming peptide is surface pressure dependent, a mixture of dimers and trimers was formedmore » at intermediate surface pressure but transitions into trimers completely upon increasing surface pressure. Moreover, the interhelical distance within the coiled-coil bundle of 3-helix peptide-PEG conjugate amphiphiles was not perturbed under high surface pressure. Present studies provide valuable insights into the self-assembly process of hybrid peptide-polymer conjugates and guidance to develop biomaterials with controlled multivalency of ligand presentation.« less

Fine-tuning of electronic properties in donor-acceptor conjugated polymers based on oligothiophenes

NASA Astrophysics Data System (ADS)

Imae, Ichiro; Sagawa, Hitoshi; Harima, Yutaka

2018-03-01

A novel series of donor-acceptor conjugated polymers having oligothiophenes with well-defined structures were synthesized and their optical, electrochemical, and photovoltaic properties were investigated. It was found that the absorption bands of polymers were red-shifted with increasing number of ethylenedioxy groups added to each oligothiophene unit and that their band edges reached over 1000 nm. The systematical fine-tuning of the electronic properties was achieved using the chemical structures of oligothiophene units. Photovoltaic cells based on polymer/(6,6)-phenyl C61 butyric acid methyl ester (PC61BM) exhibited power conversion efficiencies in the range from 0.004 to 1.10%, reflecting the electronic properties of the polymers.

Polymers modified with double-tailed fluorous compounds for efficient DNA and siRNA delivery.

PubMed

He, Bingwei; Wang, Yitong; Shao, Naimin; Chang, Hong; Cheng, Yiyun

2015-08-01

Cationic polymers are widely used as gene carriers, however, these polymers are usually associated with low transfection efficacy and non-negligible toxicity. Fluorination on polymers significantly improves their performances in gene delivery, but a high density of fluorous chains must be conjugated on a single polymer. Here we present a new strategy to construct fluorinated polymers with minimal fluorous chains for efficient DNA and siRNA delivery. A double-tailed fluorous compound 2-chloro-4,6-bis[(perfluorohexyl)propyloxy]-1,3,5-triazine (CBT) was conjugated on dendrimers of different generations and low molecular weight polyethylenimine via a facile synthesis. The yielding products with average numbers of 1-2 conjugated CBT moieties showed much improved EGFP and luciferase transfection efficacy compared to unmodified polymers. In addition, these polymers show high siRNA delivery efficacy on different cell lines. Among the synthesized polymers, generation 1 (G1) dendrimer modified with an average number of 1.9 CBT moieties (G1-CBT1.9) shows the highest efficacy when delivering both DNA and siRNA and its efficacy approaches that of Lipofectamine 2000. G1-CBT1.9 also shows efficient gene silencing in vivo. All of the CBT-modified polymers exhibit minimal toxicity on the cells at their optimal transfection conditions. This study provides a new strategy to design efficient fluorous polymers for DNA and siRNA delivery. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The Effect of Fluorine Substitution on the Molecular Interactions and Performance in Polymer Solar Cells.

PubMed

Kim, In-Bok; Jang, Soo-Young; Kim, Yeong-A; Kang, Rira; Kim, In-Sik; Ko, Do-Kyeong; Kim, Dong-Yu

2017-07-19

Fluorine (F) substitution on conjugated polymers in polymer solar cells (PSCs) has a diverse effect on molecular properties and device performance. We present a series of three D-A type conjugated polymers (PBT, PFBT, and PDFBT) based on dithienothiophene and benzothiadiazole units with different numbers of F atoms to explain the influence of F substitution by comparing the molecular interactions of the polymers and the recombination kinetics in PSCs. The preaggregation behavior of PFBT and PDFBT in o-DCB at the UV-vis absorption spectra proves that both polymers have strong intermolecular interactions. Besides, more closely packed structures and change into face-on orientation of fluorinated polymers are observed in polymer:PC 71 BM blends by GIXD which is beneficial for charge transport and, ultimately, for current density in PSCs (4.3, 13.0, and 14.5 mA cm -2 for PBT, PFBT, and PDFBT, respectively). Also, the introduction of F atoms on conjugated backbones affects the recombination kinetics by suppressing bimolecular recombination, thereby improving the fill factor (0.41, 0.68, and 0.69 for PBT, PFBT, and PDFBT, respectively). Consequently, the PCE of PSCs reached 7.3% without any additional treatment (annealing, solvent additive, etc.) in the polymer containing difluorinated BT (PDFBT) that is much higher than nonfluorinated BT (PBT ∼ 1%) and monofluorinated BT (PFBT ∼ 6%).

Theoretical analysis of single molecule spectroscopy lineshapes of conjugated polymers

NASA Astrophysics Data System (ADS)

Devi, Murali

Conjugated Polymers(CPs) exhibit a wide range of highly tunable optical properties. Quantitative and detailed understanding of the nature of excitons responsible for such a rich optical behavior has significant implications for better utilization of CPs for more efficient plastic solar cells and other novel optoelectronic devices. In general, samples of CPs are plagued with substantial inhomogeneous broadening due to various sources of disorder. Single molecule emission spectroscopy (SMES) offers a unique opportunity to investigate the energetics and dynamics of excitons and their interactions with phonon modes. The major subject of the present thesis is to analyze and understand room temperature SMES lineshapes for a particular CP, called poly(2,5-di-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (DEH-PPV). A minimal quantum mechanical model of a two-level system coupled to a Brownian oscillator bath is utilized. The main objective is to identify the set of model parameters best fitting a SMES lineshape for each of about 200 samples of DEH-PPV, from which new insight into the nature of exciton-bath coupling can be gained. This project also entails developing a reliable computational methodology for quantum mechanical modeling of spectral lineshapes in general. Well-known optimization techniques such as gradient descent, genetic algorithms, and heuristic searches have been tested, employing an L2 measure between theoretical and experimental lineshapes for guiding the optimization. However, all of these tend to result in theoretical lineshapes qualitatively different from experimental ones. This is attributed to the ruggedness of the parameter space and inadequateness of the L2 measure. On the other hand, when the dynamic reduction of the original parameter space to a 2-parameter space through feature searching and visualization of the search space paths using directed acyclic graphs(DAGs), the qualitative nature of the fitting improved significantly. For a more satisfactory fitting, it is shown that the inclusion of an additional energetic disorder is essential, representing the effect of quasi-static disorder accumulated during the SMES of each polymer. Various technical details, ambiguous issues, and implication of the present work are discussed.

Use of side-chain for rational design of n-type diketopyrrolopyrrole-based conjugated polymers: what did we find out?

PubMed

Kanimozhi, Catherine; Yaacobi-Gross, Nir; Burnett, Edmund K; Briseno, Alejandro L; Anthopoulos, Thomas D; Salzner, Ulrike; Patil, Satish

2014-08-28

The primary role of substituted side chains in organic semiconductors is to increase their solubility in common organic solvents. In the recent past, many literature reports have suggested that the side chains play a critical role in molecular packing and strongly impact the charge transport properties of conjugated polymers. In this work, we have investigated the influence of side-chains on the charge transport behavior of a novel class of diketopyrrolopyrrole (DPP) based alternating copolymers. To investigate the role of side-chains, we prepared four diketopyrrolopyrrole-diketopyrrolopyrrole (DPP-DPP) conjugated polymers with varied side-chains and carried out a systematic study of thin film microstructure and charge transport properties in polymer thin-film transistors (PTFTs). Combining results obtained from grazing incidence X-ray diffraction (GIXD) and charge transport properties in PTFTs, we conclude side-chains have a strong influence on molecular packing, thin film microstructure, and the charge carrier mobility of DPP-DPP copolymers. However, the influence of side-chains on optical properties was moderate. The preferential "edge-on" packing and dominant n-channel behavior with exceptionally high field-effect electron mobility values of >1 cm(2) V(-1) s(-1) were observed by incorporating hydrophilic (triethylene glycol) and hydrophobic side-chains of alternate DPP units. In contrast, moderate electron and hole mobilities were observed by incorporation of branched hydrophobic side-chains. This work clearly demonstrates that the subtle balance between hydrophobicity and hydrophilicity induced by side-chains is a powerful strategy to alter the molecular packing and improve the ambipolar charge transport properties in DPP-DPP based conjugated polymers. Theoretical analysis supports the conclusion that the side-chains influence polymer properties through morphology changes, as there is no effect on the electronic properties in the gas phase. The exceptional electron mobility is at least partially a result of the strong intramolecular conjugation of the donor and acceptor as evidenced by the unusually wide conduction band of the polymer.

Parallel Synthesis of photoluminescent π-conjugated polymers by polymer reactions of an organotitanium polymer with a titanacyclopentadiene unit.

PubMed

Matsumura, Yoshimasa; Fukuda, Katsura; Inagi, Shinsuke; Tomita, Ikuyoshi

2015-04-01

A regioregular organometallic polymer with titanacyclopentadiene unit, obtained by the reaction of a 2,7-diethynylfluorene derivative and a low-valent titanium complex, is subjected to the reaction with three kinds of electrophiles (i.e., sulfur monochloride, hydrochloric acid, and dichlorophenylphosphine) to give π-conjugated polymers possessing both fluorene and building blocks originated from the transformation of the titanacycles in the main chain. For example, a phosphole-containing polymer whose number-average molecular weight is estimated as 5000 is obtained in 50% yield. The obtained thiophene, butadiene, and phosphole-containing polymers exhibit efficient photoluminescence (PL) with emission colors of blue, green, and yellow, respectively. For example, the phosphole-containing polymer exhibits yellow PL with an emission maximum (Emax ) of 533 nm and a quantum yield (Φ) of 0.37. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quenching of fluorescence of conjugated poly(p-phenylene) polymers by benzil and dimethylaminobenzil molecules

NASA Astrophysics Data System (ADS)

Bagnich, S. A.; Knyukshto, V. N.

2006-11-01

We have studied the mechanisms for quenching of the fluorescence of conjugated poly(p-phenylene) polymers by benzil and dimethylaminobenzil molecules. We have shown that molecules in the diketone series are quenching agents for the fluorescence of the indicated polymers, and can serve as singlet-triplet converters capable of populating the triplet state of the polymer. We have observed that the efficiency of quenching of the fluorescence of the studied polymers depends considerably on the presence of bulky side groups in the polymer or in the activator molecules. Based on analysis of the data obtained, we conclude that in the case of a rigid planar structure for the polymer, a significant contribution to quenching of its fluorescence comes from not only singlet-singlet energy transfer but also charge transfer, leading to formation of intermolecular complexes (exciplexes).

Cell Partition in Two Polymer Aqueous Phases

NASA Technical Reports Server (NTRS)

Harris, J. M.

1985-01-01

Partition of biological cells in two phase aqueous polymer systems is recognized as a powerful separation technique which is limited by gravity. The synthesis of new, selective polymer ligand conjugates to be used in affinity partition separations is of interest. The two most commonly used polymers in two phase partitioning are dextran and polyethylene glycol. A thorough review of the chemistry of these polymers was begun, particularly in the area of protein attachment. Preliminary studies indicate the importance in affinity partitioning of minimizing gravity induced randomizing forces in the phase separation process. The PEG-protein conjugates that were prepared appear to be ideally suited for achieving high quality purifications in a microgravity environment. An interesting spin-off of this synthetic work was the observation of catalytic activity for certain of our polymer derivatives.

Sorting of Semiconducting Single-Walled Carbon Nanotubes in Polar Solvents with an Amphiphilic Conjugated Polymer Provides General Guidelines for Enrichment.

PubMed

Ouyang, Jianying; Ding, Jianfu; Lefebvre, Jacques; Li, Zhao; Guo, Chang; Kell, Arnold J; Malenfant, Patrick R L

2018-02-27

Conjugated polymer extraction (CPE) has been shown to be a highly effective method to isolate high-purity semiconducting single-walled carbon nanotubes (sc-SWCNTs). In both literature reports and industrial manufacturing, this method has enabled enrichment of sc-SWCNTs with high purity (≥99.9%). High selectivity is typically obtained in nonpolar aromatic solvents, yet polar solvents may provide process improvements in terms of yield, purity and efficiency. Using an amphiphilic fluorene-alt-pyridine conjugated copolymer with hydrophilic side chains, we have investigated the enrichment of sc-SWCNTs in polar solvents. Various conditions such as polymer/SWCNT ratio, solvent polarity, solvent dielectric constant as well as polymer solubility and SWCNT dispersibility were explored in order to optimize the purity and yield of the enriched product. Herein, we provide insights on CPE by demonstrating that a conjugated polymer having a hydrophobic backbone and hydrophilic oligo(ethylene oxide) side chains provides near full recovery (95%) of sc-SWCNTs using a multiextraction protocol. High purity is also obtained, and differences in chiral selectivity compared to analogous hydrophobic systems were confirmed by optical absorption and Raman spectroscopy as well as photoluminescence excitation mapping. Taking into consideration the solvent dielectric constant, polarity index as well as polymer solubility and SWCNT dispersibility provides a better understanding of structure-property effects on sc-SWCNT enrichment. The resulting hydrophilic SWCNT dispersions demonstrate long-term colloidal stability, making them suitable for ink formulation and high-performance thin-film transistors fabrication.

α-Methylprednisolone conjugated cyclodextrin polymer-based nanoparticles for rheumatoid arthritis therapy

PubMed Central

Hwang, Jungyeon; Rodgers, Kathleen; Oliver, James C; Schluep, Thomas

2008-01-01

A glycinate derivative of α-methylprednisolone (MP) was prepared and conjugated to a linear cyclodextrin polymer (CDP) with a loading of 12.4% w/w. The polymer conjugate (CDP-MP) self-assembled into nanoparticles with a size of 27 nm. Release kinetics of MP from the polymer conjugate showed a half-life (t1/2) of 50 h in phosphate buffer solution (PBS) and 19 h in human plasma. In vitro, the proliferation of human lymphocytes was suppressed to a similar extent but with a delayed effect when CDP-MP was compared with free MP. In vivo, CDP-MP was administered intravenously to mice with collagen-induced arthritis and compared with free MP. CDP-MP was administered weekly for six weeks (0.07, 0.7, and 7 mg/kg/week) and MP was administered daily for six weeks (0.01, 0.1, and 1 mg/kg/day). Body weight changes were minimal in all animals. After 28 days, a significant decrease in arthritis score was observed in animals treated weekly with an intermediate or high dose of CDP-MP. Additionally, dorsoplantar swelling was reduced to baseline in animals treated with CDP-MP at the intermediate and high dose level. Histological evaluation showed a reduction in synovitis, pannus formation and disruption of architecture at the highest dose level of CDP-MP. MP administered daily at equivalent cumulative doses showed minimal efficacy in this model. This study demonstrates that conjugation of MP to a cyclodextrin-polymer may improve its efficacy, leading to lower doses and less frequent administration for a safer and more convenient management of rheumatoid arthritis. PMID:18990945

Fundamental Studies on Donor-acceptor Conjugated Polymers Containing 'Heavy' Group 14 and Group 16 Elements

NASA Astrophysics Data System (ADS)

Gibson, Gregory Laird

One advantage of conjugated polymers as organic materials is that their properties may be readily tuned through covalent modifications. This thesis presents studies on the structure-property relationships resulting from single- and double-atom substitutions on an alternating donor-acceptor conjugated polymer. Specifically, single selenium and tellurium atoms have been incorporated into the acceptor monomer in place of sulfur; silicon and germanium atoms have been substituted in place of carbon at the donor monomer bridge position. The carbon-donor/ tellurium-acceptor polymer was synthesized by a post-polymerization reaction sequence and demonstrated the utility of heavy group 16 atoms to red shift a polymer absorption spectrum. Density functional theory calculations point to a new explanation for this result invoking the lower heavy atom ionization energy and reduced aromaticity of acceptor monomers containing selenium and tellurium compared to sulfur. Absorption and emission experiments demonstrate that both silicon and germanium substitutions in the donor slightly blue shift the polymer absorption spectrum. Polymers containing sulfur in the acceptor are the strongest light absorbers of all polymers studied here. Molecular weight and phenyl end capping studies show that molecular weight appears to affect polymer absorption to the greatest degree in a medium molecular weight regime and that these effects have a significant aggregation component. Solar cell devices containing either the silicon- or germanium-donor/selenium-acceptor polymer display improved red light harvesting or hole mobility relative to their structural analogues. Overall, these results clarify the effects of single atom substitution on donor-acceptor polymers and aid in the future design of polymers containing heavy atoms.

Transition-Metal-Free Synthesis of 1,3-Butadiene-Containing π-Conjugated Polymers.

PubMed

Cai, Xuediao; Liu, Yating; Lu, Tian; Yang, Rui; Luo, Chuxin; Zhang, Qi; Chai, Yonghai

2016-12-01

This work describes the synthesis of π-conjugated polymers possessing arylene and 1,3-butadiene alternating units in the main chain by the reaction of α,β-unsaturated ester/nitrile containing γ-H with aromatic/heteroaromatic aldehyde compound. By using 4-(4-formylphenyl)-2-butylene acid ethyl ester as a model monomer, the different polymerization conditions, including catalyst, catalyst amount, and solvent, are optimized. The polymerization of 4-(4-formylphenyl)-2-butylene acid ethyl ester is carried out by refluxing in ethanol for 72 h with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a catalyst to give a 1,3-butadiene-containing π-conjugated polymer, poly(phenylene-1,3-butadiene), in 84.3% yield with M¯n and M¯w/M¯n (PDI) estimated as 6172 and 1.65, respectively. Based on this new methodology, a series of π-conjugated polymers containing 1,3-butadiene units with different substituents are obtained in high yields. A possible mechanism is proposed for the polymerization through a six-membered ring transition state and then a 1,5-H shift intermediate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Characterisation of Biocompatible Polymer-Conjugated Magnetic Beads for Enhancement Stability of Urease.

PubMed

Doğaç, Yasemin Ispirli; Teke, Mustafa

2016-04-01

We reported natural polymer-conjugated magnetic featured urease systems for removal of urea effectively. The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4-70 °C), pH stability (4.0-9.0), operational stability (0-250 min), reusability (18 times) and storage stability (24 weeks) were studied for characterisation of the urease-encapsulated biocompatible polymer-conjugated magnetic beads. Also, the surface groups and chemical structure of the magnetic beads were determined by using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The all urease-encapsulated magnetic beads protected their stability of 30-45 % relative activity at 70 °C. A significant increase was observed at their pH stability compared with the free urease for both acidic and alkaline medium. Besides this, their repeatability activity were approximately 100 % during 4(th) run. They showed residual activity of 50 % after 16 weeks. The importance of this work is enhancement stability of immobilised urease by biocompatible polymer-conjugated magnetic beads for the industrial application based on removal of urea.

Electrospun Polymer Fibers for Electronic Applications

PubMed Central

Luzio, Alessandro; Canesi, Eleonora Valeria; Bertarelli, Chiara; Caironi, Mario

2014-01-01

Nano- and micro- fibers of conjugated polymer semiconductors are particularly interesting both for applications and for fundamental research. They allow an investigation into how electronic properties are influenced by size confinement and chain orientation within microstructures that are not readily accessible within thin films. Moreover, they open the way to many applications in organic electronics, optoelectronics and sensing. Electro-spinning, the technique subject of this review, is a simple method to effectively form and control conjugated polymer fibers. We provide the basics of the technique and its recent advancements for the formation of highly conducting and high mobility polymer fibers towards their adoption in electronic applications. PMID:28788493

Well-defined protein-polymer conjugates--synthesis and potential applications.

PubMed

Thordarson, Pall; Le Droumaguet, Benjamin; Velonia, Kelly

2006-11-01

During the last decades, numerous studies have focused on combining the unique catalytic/functional properties and structural characteristics of proteins and enzymes with those of synthetic molecules and macromolecules. The aim of such multidisciplinary studies is to improve the properties of the natural component, combine them with those of the synthetic, and create novel biomaterials in the nanometer scale. The specific coupling of polymers onto the protein structures has proved to be one of the most straightforward and applicable approaches in that sense. In this article, we focus on the synthetic pathways that have or can be utilized to specifically couple proteins to polymers. The different categories of well-defined protein-polymer conjugates and the effect of the polymer on the protein function are discussed. Studies have shown that the specific conjugation of a synthetic polymer to a protein conveys its physico-chemical properties and, therefore, modifies the biodistribution and solubility of the protein, making it in certain cases soluble and active in organic solvents. An overview of the applications derived from such bioconjugates in the pharmaceutical industry, biocatalysis, and supramolecular nanobiotechnology is presented at the final part of the article.

Polymer therapeutics: Top 10 selling pharmaceuticals - what next?

PubMed

Duncan, Ruth

2014-09-28

At the time of the first issue of the Journal of Controlled Release (JCR), polymeric drugs, polymer-drug and protein conjugates and block copolymer micelles carrying bound drugs, i.e. polymer therapeutics, were still regarded as scientific curiosities with little or no prospect of generating practical to use medicines. How this perception has changed. Many major Pharma now have R&D programmes in this area and in 2013 two polymer therapeutics, Copaxone and Neulasta, are featured in the Top 10 US pharmaceutical sales list. Although there are a growing number of marketed products (e.g. PEGylated proteins, a PEG-aptamer and oral polymeric sequestrants), and the first follow-on (generic products) are emerging, the first polymer-drug conjugates and block copolymer micelle products (as covalent conjugates) have yet to enter routine clinical use. Industrial familiarity and recent advances in the underpinning scientific disciplines will no doubt accelerate the transfer of polymer therapeutics into clinically useful medicines and imaging agents. This short personal perspective reflects on the current status of polymer therapeutics and the future opportunities to improve their successful translation. It adds to recent and historical reviews that comprehensively document the evolution of the field since JCR was born. Copyright © 2014 Elsevier B.V. All rights reserved.

Assembly of polythiophenes on responsive polymer microgels for the highly selective detection of ammonia gas

DOE PAGES

Chang, Aiping; Peng, Yahui; Li, Zezhou; ...

2016-04-05

For this study, a class of smart composite materials based on the assembly of conjugated polymers on responsive polymer microgels has been prepared. We have chosen poly(3-((2-(2-methoxyethoxy)ethoxy)methyl)-thiophene) as the model conjugated polymer and an ammonia-responsive microgel of phenoxazinium-functionalized poly(N-isopropylacrylamide-co-propargyl acrylate) as the model template. Under this design, the composite materials can combine the electrical conductivity of the conjugated polymers and the ammonia recognisability of the ammonia-responsive polymer microgels; the cooperation of these properties allows the reversible control of electrical conductivity by ammonia gas. Those composite materials can not only adapt to ammonia gas, but also convert changes in the concentrationmore » of ammonia into conductance, allowing the electrical detection of ammonia gas with high selectivity. This makes the composite materials different from the conductive polymer platforms reported previously, which may also respond to non-ammonia gases and the response induced by non-ammonia gases is close to that induced by ammonia gas. Using these composite materials as sensing materials for the electrical detection of ammonia gas, the detection limit can reach as low as 1.1 ppb. Finally, these features enable their use for the electrical detection of ammonia in breath.« less

Assembly of polythiophenes on responsive polymer microgels for the highly selective detection of ammonia gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Aiping; Peng, Yahui; Li, Zezhou

For this study, a class of smart composite materials based on the assembly of conjugated polymers on responsive polymer microgels has been prepared. We have chosen poly(3-((2-(2-methoxyethoxy)ethoxy)methyl)-thiophene) as the model conjugated polymer and an ammonia-responsive microgel of phenoxazinium-functionalized poly(N-isopropylacrylamide-co-propargyl acrylate) as the model template. Under this design, the composite materials can combine the electrical conductivity of the conjugated polymers and the ammonia recognisability of the ammonia-responsive polymer microgels; the cooperation of these properties allows the reversible control of electrical conductivity by ammonia gas. Those composite materials can not only adapt to ammonia gas, but also convert changes in the concentrationmore » of ammonia into conductance, allowing the electrical detection of ammonia gas with high selectivity. This makes the composite materials different from the conductive polymer platforms reported previously, which may also respond to non-ammonia gases and the response induced by non-ammonia gases is close to that induced by ammonia gas. Using these composite materials as sensing materials for the electrical detection of ammonia gas, the detection limit can reach as low as 1.1 ppb. Finally, these features enable their use for the electrical detection of ammonia in breath.« less

Steric Pressure among Membrane-Bound Polymers Opposes Lipid Phase Separation.

PubMed

Imam, Zachary I; Kenyon, Laura E; Carrillo, Adelita; Espinoza, Isai; Nagib, Fatema; Stachowiak, Jeanne C

2016-04-19

Lipid rafts are thought to be key organizers of membrane-protein complexes in cells. Many proteins that interact with rafts have bulky polymeric components such as intrinsically disordered protein domains and polysaccharide chains. Therefore, understanding the interaction between membrane domains and membrane-bound polymers provides insights into the roles rafts play in cells. Multiple studies have demonstrated that high concentrations of membrane-bound polymeric domains create significant lateral steric pressure at membrane surfaces. Furthermore, our recent work has shown that lateral steric pressure at membrane surfaces opposes the assembly of membrane domains. Building on these findings, here we report that membrane-bound polymers are potent suppressors of membrane phase separation, which can destabilize lipid domains with substantially greater efficiency than globular domains such as membrane-bound proteins. Specifically, we created giant vesicles with a ternary lipid composition, which separated into coexisting liquid ordered and disordered phases. Lipids with saturated tails and poly(ethylene glycol) (PEG) chains conjugated to their head groups were included at increasing molar concentrations. When these lipids were sparse on the membrane surface they partitioned to the liquid ordered phase. However, as they became more concentrated, the fraction of GUVs that were phase-separated decreased dramatically, ultimately yielding a population of homogeneous membrane vesicles. Experiments and physical modeling using compositions of increasing PEG molecular weight and lipid miscibility phase transition temperature demonstrate that longer polymers are the most efficient suppressors of membrane phase separation when the energetic barrier to lipid mixing is low. In contrast, as the miscibility transition temperature increases, longer polymers are more readily driven out of domains by the increased steric pressure. Therefore, the concentration of shorter polymers required to suppress phase separation decreases relative to longer polymers. Collectively, our results demonstrate that crowded, membrane-bound polymers are highly efficient suppressors of phase separation and suggest that the ability of lipid domains to resist steric pressure depends on both their lipid composition and the size and concentration of the membrane-bound polymers they incorporate.

Subgap Absorption in Conjugated Polymers

DOE R&D Accomplishments Database

Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

1991-01-01

Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

Conjugation of bioactive groups to poly(lactic acid) and poly[(lactic acid)-co-(glycolic acid)] films.

PubMed

Prime, Emma L; Cooper-White, Justin J; Qiao, Greg G

2007-12-06

A novel PLA-based polymer containing reactive pendent ketone or hydroxyl groups was synthesized by the copolymerization of L-lactide with epsilon-caprolactone-based monomers. The polymer was activated with NPC, resulting in an amine-reactive polymer which was then cast into thin polymeric films, either alone or as part of a blend with PLGA, before immersion into a solution of the cell adhesion peptide GRGDS in PBS buffer allowed for conjugation of GRGDS to the film surfaces. Subsequent 3T3 fibroblast cell adhesion studies demonstrated an increase in cellular adhesion and spreading over films cast from unmodified PLGA. Hence the new polymer can be used to obtain covalent linkage of amine-containing molecules to polymer surfaces.

Particle-in-a-box model of one-dimensional excitons in conjugated polymers

NASA Astrophysics Data System (ADS)

Pedersen, Thomas G.; Johansen, Per M.; Pedersen, Henrik C.

2000-04-01

A simple two-particle model of excitons in conjugated polymers is proposed as an alternative to usual highly computationally demanding quantum chemical methods. In the two-particle model, the exciton is described as an electron-hole pair interacting via Coulomb forces and confined to the polymer backbone by rigid walls. Furthermore, by integrating out the transverse part, the two-particle equation is reduced to one-dimensional form. It is demonstrated how essentially exact solutions are obtained in the cases of short and long conjugation length, respectively. From a linear combination of these cases an approximate solution for the general case is obtained. As an application of the model the influence of a static electric field on the electron-hole overlap integral and exciton energy is considered.

A Donor-Acceptor Conjugated Polymer with Alternating Isoindigo Derivative and Bithiophene Units for Near-Infrared Modulated Cancer Thermo-Chemotherapy.

PubMed

Li, Dong-Dong; Wang, Jun-Xia; Ma, Yan; Qian, Hai-Sheng; Wang, Dong; Wang, Li; Zhang, Guobing; Qiu, Longzhen; Wang, Yu-Cai; Yang, Xian-Zhu

2016-08-03

Conjugated polymers containing alternating donor/acceptor units have strong and sharp absorbance peaks in near-infrared (NIR) region, which could be suitable for photothermal therapy. However, these polymers as photothermal transducers are rarely reported because of their water insolubility, which limits their applications for cancer therapy. Herein, we report the donor-acceptor conjugated polymer PBIBDF-BT with alternating isoindigo derivative (BIBDF) and bithiophene (BT) units as a novel photothermal transducer, which exhibited strong near-infrared (NIR) absorbance due to its low band gap (1.52 eV). To stabilize the conjugated polymer physiological environments, we utilized an amphiphilic copolymer, poly(ethylene glycol)-block-poly(hexyl ethylene phosphate) (mPEG-b-PHEP), to stabilize PBIBDF-BT-based nanoparticles (PBIBDF-BT@NPPPE) through a single emulsion method. The obtained nanoparticles PBIBDF-BT@NPPPE showed great stability in physiological environments and excellent photostability. Moreover, the PBIBDF-BT@NPPPE exhibited high photothermal conversion efficiency, reaching 46.7%, which is relatively high compared with those of commonly used materials for photothermal therapy. Accordingly, in vivo and in vitro experiments demonstrated that PBIBDF-BT@NPPPE exhibits efficient photothermal anticancer efficacy. More importantly, PBIBDF-BT@NPPPE could simultaneously encapsulate other types of therapeutic agents though hydrophobic interactions with the PHEP core and achieve NIR-triggered intracellular drug release and a synergistic combination therapy of thermo-chemotherapy for the treatment of cancer.

Conjugated polymers/semiconductor nanocrystals hybrid materials--preparation, electrical transport properties and applications.

PubMed

Reiss, Peter; Couderc, Elsa; De Girolamo, Julia; Pron, Adam

2011-02-01

This critical review discusses specific preparation and characterization methods applied to hybrid materials consisting of π-conjugated polymers (or oligomers) and semiconductor nanocrystals. These materials are of great importance in the quickly growing field of hybrid organic/inorganic electronics since they can serve as active components of photovoltaic cells, light emitting diodes, photodetectors and other devices. The electronic energy levels of the organic and inorganic components of the hybrid can be tuned individually and thin hybrid films can be processed using low cost solution based techniques. However, the interface between the hybrid components and the morphology of the hybrid directly influences the generation, separation and transport of charge carriers and those parameters are not easy to control. Therefore a large variety of different approaches for assembling the building blocks--conjugated polymers and semiconductor nanocrystals--has been developed. They range from their simple blending through various grafting procedures to methods exploiting specific non-covalent interactions between both components, induced by their tailor-made functionalization. In the first part of this review, we discuss the preparation of the building blocks (nanocrystals and polymers) and the strategies for their assembly into hybrid materials' thin films. In the second part, we focus on the charge carriers' generation and their transport within the hybrids. Finally, we summarize the performances of solar cells using conjugated polymer/semiconductor nanocrystals hybrids and give perspectives for future developments.

The marriage of metallacycle transfer chemistry with Suzuki-Miyaura cross-coupling to give main group element-containing conjugated polymers.

PubMed

He, Gang; Kang, Le; Torres Delgado, William; Shynkaruk, Olena; Ferguson, Michael J; McDonald, Robert; Rivard, Eric

2013-04-10

A versatile and general synthetic route for the synthesis of conjugated main group element-based polymers, previously inaccessible by conventional means, is reported. These polymers contain five-membered chalcogenophene rings based on S, Se, and Te, and we demonstrate that optoelectronic properties can be readily tuned via controlled atom substitution chemistry. In addition, regioregular hybrid thiophene-selenophene-tellurophene and selenophene-fluorene copolymers were synthesized to provide a further illustration of the scope of the presented metallacycle transfer/cross-coupling polymerization method.

Trehalose Glycopolymer Enhances Both Solution Stability and Pharmacokinetics of a Therapeutic Protein.

PubMed

Liu, Yang; Lee, Juneyoung; Mansfield, Kathryn M; Ko, Jeong Hoon; Sallam, Sahar; Wesdemiotis, Chrys; Maynard, Heather D

2017-03-15

Biocompatible polymers such as poly(ethylene glycol) (PEG) have been successfully conjugated to therapeutic proteins to enhance their pharmacokinetics. However, many of these polymers, including PEG, only improve the in vivo lifetimes and do not protect proteins against inactivation during storage and transportation. Herein, we report a polymer with trehalose side chains (PolyProtek) that is capable of improving both the external stability and the in vivo plasma half-life of a therapeutic protein. Insulin was employed as a model biologic, and high performance liquid chromatography and dynamic light scattering confirmed that addition of trehalose glycopolymer as an excipient or covalent conjugation prevented thermal or agitation-induced aggregation of insulin. The insulin-trehalose glycopolymer conjugate also showed significantly prolonged plasma circulation time in mice, similar to the analogous insulin-PEG conjugate. The insulin-trehalose glycopolymer conjugate was active as tested by insulin tolerance tests in mice and retained bioactivity even after exposure to high temperatures. The trehalose glycopolymer was shown to be nontoxic to mice up to at least 1.6 mg/kg dosage. These results together suggest that the trehalose glycopolymer should be further explored as an alternative to PEG for long circulating protein therapeutics.

Conjugated Polymers Atypically Prepared in Water

PubMed Central

Invernale, Michael A.; Pendergraph, Samuel A.; Yavuz, Mustafa S.; Ombaba, Matthew; Sotzing, Gregory A.

2010-01-01

Processability remains a fundamental issue for the implementation of conducting polymer technology. A simple synthetic route towards processable precursors to conducting polymers (main chain and side chain) was developed using commercially available materials. These soluble precursor systems were converted to conjugated polymers electrochemically in aqueous media, offering a cheaper and greener method of processing. Oxidative conversion in aqueous and organic media each produced equivalent electrochromics. The precursor method enhances the yield of the electrochromic polymer obtained over that of electrodeposition, and it relies on a less corruptible electrolyte bath. However, electrochemical conversion of the precursor polymers often relies on organic salts and solvents. The ability to achieve oxidative conversion in brine offers a less costly and a more environmentally friendly processing step. It is also beneficial for biological applications. The electrochromics obtained herein were evaluated for electronic, spectral, and morphological properties. PMID:20959869

Accessing conjugated polymers with precisely controlled heterobisfunctional chain ends via post-polymerization modification of the OTf group and controlled Pd(0)/t-Bu 3P-catalyzed Suzuki cross-coupling polymerization

DOE PAGES

Hu, Qiao -Sheng; Hong, Kunlun; Zhang, Hong -Hai

2015-08-12

In this study, a general strategy toward the synthesis of well-defined conjugated polymers with controlled heterobisfunctional chain ends via combination of controlled Pd(0)/t-Bu 3P Suzuki cross-coupling polymerization with the post-polymerization modification of the triflate (OTf) group was disclosed.

A conjugated microporous polymer based visual sensing platform for aminoglycoside antibiotics in water.

PubMed

Bhunia, Subhajit; Dey, Nilanjan; Pradhan, Anirban; Bhattacharya, Santanu

2018-06-20

A donor-acceptor based conjugated microporous polymer, PER@NiP-CMOP-1, has been synthesized which can achieve highly sensitive stereo-specific "Turn ON" biosensing of an aminoglycoside up to the ppb level. The coordination-driven inhibition of photo-induced electron transfer (d-PET) for d-electrons and the rotational freezing are the key factors for the recovery of the emission.

Accessing conjugated polymers with precisely controlled heterobisfunctional chain ends via post-polymerization modification of the OTf group and controlled Pd(0)/t-Bu 3P-catalyzed Suzuki cross-coupling polymerization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Qiao -Sheng; Hong, Kunlun; Zhang, Hong -Hai

In this study, a general strategy toward the synthesis of well-defined conjugated polymers with controlled heterobisfunctional chain ends via combination of controlled Pd(0)/t-Bu 3P Suzuki cross-coupling polymerization with the post-polymerization modification of the triflate (OTf) group was disclosed.

Efficient separation of conjugated polymers using a water soluble glycoprotein matrix: from fluorescence materials to light emitting devices.

PubMed

Hendler, Netta; Wildeman, Jurjen; Mentovich, Elad D; Schnitzler, Tobias; Belgorodsky, Bogdan; Prusty, Deepak K; Rimmerman, Dolev; Herrmann, Andreas; Richter, Shachar

2014-03-01

Optically active bio-composite blends of conjugated polymers or oligomers are fabricated by complexing them with bovine submaxilliary mucin (BSM) protein. The BSM matrix is exploited to host hydrophobic extended conjugated π-systems and to prevent undesirable aggregation and render such materials water soluble. This method allows tuning the emission color of solutions and films from the basic colors to the technologically challenging white emission. Furthermore, electrically driven light emitting biological devices are prepared and operated. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrafast intersystem-crossing in platinum containing π-conjugated polymers with tunable spin-orbit coupling.

PubMed

Sheng, C-X; Singh, S; Gambetta, A; Drori, T; Tong, M; Tretiak, S; Vardeny, Z V

2013-01-01

The development of efficient organic light-emitting diodes (OLED) and organic photovoltaic cells requires control over the dynamics of spin sensitive excitations. Embedding heavy metal atoms in π-conjugated polymer chains enhances the spin-orbit coupling (SOC), and thus facilitates intersystem crossing (ISC) from the singlet to triplet manifolds. Here we use various nonlinear optical spectroscopies such as two-photon absorption and electroabsorption in conjunction with electronic structure calculations, for studying the energies, emission bands and ultrafast dynamics of spin photoexcitations in two newly synthesized π-conjugated polymers that contain intrachain platinum (Pt) atoms separated by one (Pt-1) or three (Pt-3) organic spacer units. The controllable SOC in these polymers leads to a record ISC time of <~1 ps in Pt-1 and ~6 ps in Pt-3. The tunable ultrafast ISC rate modulates the intensity ratio of the phosphorescence and fluorescence emission bands, with potential applications for white OLEDs.

Tetraphenylethylene-Interweaving Conjugated Macrocycle Polymer Materials as Two-Photon Fluorescence Sensors for Metal Ions and Organic Molecules.

PubMed

Li, Xi; Li, Zheng; Yang, Ying-Wei

2018-05-01

A luminescent conjugated macrocycle polymer (CMP) with strong two-photon fluorescence property, namely, P[5]-TPE-CMP, is constructed from ditriflate-functionalized pillar[5]arene and a 1,1,2,2-tetrakis(4-ethynylphenyl)ethylene (TPE) linker through a Sonogashira-Hagihara cross-coupling reaction. Significantly, in sharp contrast with the corresponding conjugated microporous polymer without synthetic macrocycles, P[5]-TPE-CMP shows an outstanding stability against photobleaching and exhibits highly selective cation sensing capability toward Fe 3+ at different excitation wavelengths (both UV and red-near-infrared regions). Meanwhile, its fluorescence could also be sufficiently quenched by 4-amino azobenzene, a frequently used organic dye that is certified to be carcinogenic, as compared with a group of common organic compounds. This work paves a new way for enhancing the properties of porous organic polymers through the introduction of supramolecular macrocycles like macrocyclic arenes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Organic nanoparticles for photovoltaic and sensing applications

NASA Astrophysics Data System (ADS)

Venkatraman, B. Harihara

2011-12-01

Can organic semiconducting nanoparticles be used as building blocks for fabricating electronic devices? The first half of this dissertation focuses on addressing this question and the associated research challenges for attaining morphological control pertaining to organic photovoltaic devices by nanoparticle assembly. Conjugated polymer nanoparticles were synthesized using miniemulsion technique and their optical, charge transfer and charge transport properties were studied. Some degree of control in polymer chain packing within the nanoparticle was also demonstrated. The optical, charge transfer and charge transport properties of these nanoparticles were found to be similar to that of parent conjugated polymer irrespective of the surface charge. From the initial photovoltaic measurements, it is shown that these nanoparticles are potential candidates for fabricating future photovoltaic devices. The second half of this dissertation is focused on developing a novel and viable strategy for sensing aqueous based nitroaromatic compounds. Nitroaromatic compounds are commonly used as explosives and possess serious health hazards. Thiophene-based conjugated polymer nanoparticles were synthesized and were shown to effectively detect aqueous based nitroaromatic explosives.

From Semi- to Full-Two-Dimensional Conjugated Side-Chain Design: A Way toward Comprehensive Solar Energy Absorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, Pengjie; Wang, Huan; Qu, Shiwei

Two polymers with fully two-dimensional (2D) conjugated side chains, 2D-PTB-Th and 2D-PTB-TTh, were synthesized and characterized through simultaneously integrating the 2D-TT and the 2D-BDT monomers onto the polymer backbone. Resulting from the synergistic effect from the conjugated side chains on both monomers, the two polymers showed remarkably efficient absorption of the sunlight and improved pi-pi intermolecular interactions for efficient charge carrier transport. The optimized bulk heterojunction device based on 2D-PTB-Th and PC71BM shows a higher PCE of 9.13% compared to PTB7-Th with a PCE of 8.26%, which corresponds to an approximately 10% improvement in solar energy conversion. The fully 2D-conjugatedmore » side-chain concept reported here developed a new molecular design strategy for polymer materials with enhanced sunlight absorption and efficient solar energy conversion.« less

Polymer mechanochemistry: Up another rung

NASA Astrophysics Data System (ADS)

Craig, Stephen L.

2017-12-01

The use of mechanical force to break and build chemical bonds in polymers can enable transformations that cannot be conducted using stimuli such as light and heat. Now, an insulating polymer has been mechanically unzipped to create a semiconducting polymer with extended regions of conjugation.

Molecularly Engineered Polymer-Based Systems in Drug Delivery and Regenerative Medicine.

PubMed

Piluso, Susanna; Soultan, Al Halifa; Patterson, Jennifer

2017-01-01

Polymer-based systems are attractive in drug delivery and regenerative medicine due to the possibility of tailoring their properties and functions to a specific application. The present review provides several examples of molecularly engineered polymer systems, including stimuli responsive polymers and supramolecular polymers. The advent of controlled polymerization techniques has enabled the preparation of polymers with controlled molecular weight and well-defined architecture. By using these techniques coupled to orthogonal chemical modification reactions, polymers can be molecularly engineered to incorporate functional groups able to respond to small changes in the local environment or to a specific biological signal. This review highlights the properties and applications of stimuli-responsive systems and polymer therapeutics, such as polymer-drug conjugates, polymer-protein conjugates, polymersomes, and hyperbranched systems. The applications of polymeric membranes in regenerative medicine are also discussed. The examples presented in this review suggest that the combination of membranes with polymers that are molecularly engineered to respond to specific biological functions could be relevant in the field of regenerative medicine. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

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

PubMed

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, displayed high DNA binding efficiency and pH-sensitive release.

Developments in the Field of Conducting and Non-conducting Polymer Based Potentiometric Membrane Sensors for Ions Over the Past Decade

PubMed Central

Faridbod, Farnoush; Ganjali, Mohammad Reza; Dinarvand, Rassoul; Norouzi, Parviz

2008-01-01

Many research studies have been conducted on the use of conjugated polymers in the construction of chemical sensors including potentiometric, conductometric and amperometric sensors or biosensors over the last decade. The induction of conductivity on conjugated polymers by treating them with suitable oxidizing agents won Heeger, MacDiarmid and Shirakawa the 2000 Nobel Prize in Chemistry. Common conjugated polymers are poly(acetylene)s, poly(pyrrole)s, poly(thiophene)s, poly(terthiophene)s, poly(aniline)s, poly(fluorine)s, poly(3-alkylthiophene)s, polytetrathiafulvalenes, poly-napthalenes, poly(p-phenylene sulfide), poly(p-phenylenevinylene)s, poly(3,4-ethylene-dioxythiophene), polyparaphenylene, polyazulene, polyparaphenylene sulfide, poly-carbazole and polydiaminonaphthalene. More than 60 sensors for inorganic cations and anions with different characteristics based on conducting polymers have been reported. There have also been reports on the application of non-conducting polymers (nCPs), i.e. PVC, in the construction of potentiometric membrane sensors for determination of more than 60 inorganic cations and anions. However, the leakage of ionophores from the membranes based on these polymers leads to relatively lower life times. In this article, we try to give an overview of Solid-Contact ISE (SCISE), Single-Piece ISE (SPISE), Conducting Polymer (CP)-Based, and also non-conducting polymer PVC-based ISEs for various ions which their difference is in the way of the polymer used with selective\\ membrane. In SCISEs and SPISEs, the plasticized PVC containing the ionophore and ionic additives govern the selectivity behavior of the electrode and the conducting polymer is responsible of ion-to-electron transducer. However, in CPISEs, the conducting polymer layer is doped with a suitable ionophore which enhances the ion selectivity of the CP while its redox response has to be suppressed. PMID:27879825

Synthesis of Thiolated Alginate and Evaluation of Mucoadhesiveness, Cytotoxicity and Release Retardant Properties

PubMed Central

Jindal, A. B.; Wasnik, M. N.; Nair, Hema A.

2010-01-01

Modification of polymers by covalent attachment of thiol bearing pendant groups is reported to impart many beneficial properties to them. Hence in the present study, sodium alginate–cysteine conjugate was synthesized by carbodiimide mediated coupling under varying reaction conditions and the derivatives characterized for thiol content. The thiolated alginate species synthesized had bound thiol content ranging from 247.8±11.03–324.54±10.107 ΅mol/g of polymer depending on the reaction conditions. Matrix tablets based on sodium alginate-cysteine conjugate and native sodium alginate containing tramadol hydrochloride as a model drug were prepared and mucoadhesive strength and in vitro drug release from the tablets were compared. Tablets containing 75 mg sodium alginate-cysteine conjugate could sustain release of 10 mg of model drug for 3 h, whereas 90% of the drug was released within 1 h from corresponding tablets prepared using native sodium alginate. An approximately 2-fold increase in the minimal detachment force of the tablets from an artificial mucin film was observed for sodium alginate–cysteine conjugate as compared to native sodium alginate. In vitro cytotoxicity studies in L-929 mouse fibroblast cells studied using an MTT assay revealed that at low concentrations of polymer, sodium alginate–cysteine conjugate was less toxic to L-929 mouse fibroblast cell line when compared to native sodium alginate. Hence, thiolation is found to be a simple route to improving polymer performance. The combination of improved controlled drug release and mucoadhesive properties coupled with the low toxicity of these new excipients builds up immense scope for the use of thiolated polymers in mucoadhesive drug delivery systems. PMID:21969750

Spectral engineering in π-conjugated polymers with intramolecular donor-acceptor interactions.

PubMed

Beaujuge, Pierre M; Amb, Chad M; Reynolds, John R

2010-11-16

With the development of light-harvesting organic materials for solar cell applications and molecular systems with fine-tuned colors for nonemissive electrochromic devices (e.g., smart windows, e-papers), a number of technical challenges remain to be overcome. Over the years, the concept of "spectral engineering" (tailoring the complex interplay between molecular physics and the various optical phenomena occurring across the electromagnetic spectrum) has become increasingly relevant in the field of π-conjugated organic polymers. Within the spectral engineering toolbox, the "donor-acceptor" approach uses alternating electron-rich and electron-deficient moieties along a π-conjugated backbone. This approach has proved especially valuable in the synthesis of dual-band and broadly absorbing chromophores with useful photovoltaic and electrochromic properties. In this Account, we highlight and provide insight into a present controversy surrounding the origin of the dual band of absorption sometimes encountered in semiconducting polymers structured using the "donor-acceptor" approach. Based on empirical evidence, we provide some schematic representations to describe the possible mechanisms governing the evolution of the two-band spectral absorption observed on varying the relative composition of electron-rich and electron-deficient substituents along the π-conjugated backbone. In parallel, we draw attention to the choice of the method employed to estimate and compare the absorption coefficients of polymer chromophores exhibiting distinct repeat unit lengths, and containing various extents of solubilizing side-chains along their backbone. Finally, we discuss the common assumption that "donor-acceptor" systems should have systematically lower absorption coefficients than their "all-donor" counterparts. The proposed models point toward important theoretical parameters which could be further explored at the macromolecular level to help researchers take full advantage of the complex interactions taking place in π-conjugated polymers with intramolecular "donor-acceptor" characteristics.

Well-Balanced Ambipolar Conjugated Polymers Featuring Mild Glass Transition Temperatures Toward High-Performance Flexible Field-Effect Transistors.

PubMed

Shi, Keli; Zhang, Weifeng; Gao, Dong; Zhang, Shiying; Lin, Zuzhang; Zou, Ye; Wang, Liping; Yu, Gui

2018-03-01

Conjugated polymers, which can be fabricated by simple processing techniques and possess excellent electrical performance, are key to the fabrication of flexible polymer field-effect transistors (PFETs) and integrated circuits. Herein, two ambipolar conjugated polymers based on (3E,7E)-3,7-bis(2-oxo-1H-pyrrolo[2,3-b]pyridin-3(2H)-ylidene)benzo[1,2-b:4,5-b']difuran-2,6(3H,7H)-dione and dithienylbenzothiadiazole units, namely PNBDOPV-DTBT and PNBDOPV-DTF2BT, are developed. Both copolymers possess almost planar conjugated backbone conformations and suitable highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energy levels (-5.64/-4.38 eV for PNBDOPV-DTBT and -5.79/-4.48 eV for PNBDOPV-DTF2BT). Note that PNBDOPV-DTBT has a glass transition temperature (140 °C) lower than the deformation temperature of polyethylene terephthalate (PET), meaning well-ordered molecular packing can be obtained on PET substrate before its deformation in mild thermal annealing process. Flexible PFETs based on PNBDOPV-DTBT fabricated on PET substrates exhibit high and well-balanced hole/electron mobilities of 4.68/4.72 cm 2 V -1 s -1 under ambient conditions. After the further modification of Au source/drain electrodes with 1-octanethiol self-assembled monolayers, impressively high and well-balanced hole/electron mobilities up to 5.97/7.07 cm 2 V -1 s -1 are achieved in the flexible PFETs. Meanwhile, flexible complementary-like inverters based on PNBDOPV-DTBT on PET substrate also afford a much high gain of 148. The device performances of both the PFETs and inverters are among the highest values for ambipolar conjugated polymers reported to date. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrafast dynamics in multifunctional Ru(II)-loaded polymers for solar energy conversion.

PubMed

Morseth, Zachary A; Wang, Li; Puodziukynaite, Egle; Leem, Gyu; Gilligan, Alexander T; Meyer, Thomas J; Schanze, Kirk S; Reynolds, John R; Papanikolas, John M

2015-03-17

The use of sunlight to make chemical fuels (i.e., solar fuels) is an attractive approach in the quest to develop sustainable energy sources. Using nature as a guide, assemblies for artificial photosynthesis will need to perform multiple functions. They will need to be able to harvest light across a broad region of the solar spectrum, transport excited-state energy to charge-separation sites, and then transport and store redox equivalents for use in the catalytic reactions that produce chemical fuels. This multifunctional behavior will require the assimilation of multiple components into a single macromolecular system. A wide variety of different architectures including porphyrin arrays, peptides, dendrimers, and polymers have been explored, with each design posing unique challenges. Polymer assemblies are attractive due to their relative ease of production and facile synthetic modification. However, their disordered nature gives rise to stochastic dynamics not present in more ordered assemblies. The rational design of assemblies requires a detailed understanding of the energy and electron transfer events that follow light absorption, which can occur on time scales ranging from femtoseconds to hundreds of microseconds, necessitating the use of sophisticated techniques. We have used a combination of time-resolved absorption and emission spectroscopies with observation times that span 9 orders of magnitude to follow the excited-state evolution within polymer-based molecular assemblies. We complement experimental observations with molecular dynamics simulations to develop a microscopic view of these dynamics. This Account provides an overview of our work on polymers decorated with pendant Ru(II) chromophores, both in solution and on surfaces. We have examined site-to-site energy transport among the Ru(II) complexes, and in systems incorporating π-conjugated polymers, we have observed ultrafast formation of a long-lived charge-separated state. When attached to TiO2, these assemblies exhibit multifunctional behavior in which photon absorption is followed by energy transport to the surface and electron injection to produce an oxidized metal complex. The oxidizing equivalent is then transferred to the conjugated polymer, giving rise to a long-lived charge-separated state.

Conjugated Polymers/DNA Hybrid Materials for Protein Inactivation.

PubMed

Zhao, Likun; Zhang, Jiangyan; Xu, Huiming; Geng, Hao; Cheng, Yongqiang

2016-09-07

Chromophore-assisted light inactivation (CALI) is a powerful tool for analyzing protein functions due to the high degree of spatial and temporal resolution. In this work, we demonstrate a CALI approach based on conjugated polymers (CPs)/DNA hybrid material for protein inactivation. The target protein is conjugated with single-stranded DNA in advance. Single-stranded DNA can form CPs/DNA hybrid material with cationic CPs via electrostatic and hydrophobic interactions. Through the formation of CPs/DNA hybrid material, the target protein that is conjugated with DNA is brought into close proximity to CPs. Under irradiation, CPs harvest light and generate reactive oxygen species (ROS), resulting in the inactivation of the adjacent target protein. This approach can efficiently inactivate any target protein which is conjugated with DNA and has good specificity and universality, providing a new strategy for studies of protein function and adjustment of protein activity.

Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

PubMed Central

Botiz, Ioan; Stingelin, Natalie

2014-01-01

It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties. PMID:28788568

Cyclic Peptide-Polymer Nanotubes as Efficient and Highly Potent Drug Delivery Systems for Organometallic Anticancer Complexes.

PubMed

Larnaudie, Sophie C; Brendel, Johannes C; Romero-Canelón, Isolda; Sanchez-Cano, Carlos; Catrouillet, Sylvain; Sanchis, Joaquin; Coverdale, James P C; Song, Ji-Inn; Habtemariam, Abraha; Sadler, Peter J; Jolliffe, Katrina A; Perrier, Sébastien

2018-01-08

Functional drug carrier systems have potential for increasing solubility and potency of drugs while reducing side effects. Complex polymeric materials, particularly anisotropic structures, are especially attractive due to their long circulation times. Here, we have conjugated cyclic peptides to the biocompatible polymer poly(2-hydroxypropyl methacrylamide) (pHPMA). The resulting conjugates were functionalized with organoiridium anticancer complexes. Small angle neutron scattering and static light scattering confirmed their self-assembly and elongated cylindrical shape. Drug-loaded nanotubes exhibited more potent antiproliferative activity toward human cancer cells than either free drug or the drug-loaded polymers, while the nanotubes themselves were nontoxic. Cellular accumulation studies revealed that the increased potency of the conjugate appears to be related to a more efficient mode of action rather than a higher cellular accumulation of iridium.

On the suitability of nanocrystalline ferrites as a magnetic carrier for drug delivery: functionalization, conjugation and drug release kinetics.

PubMed

Rana, S; Gallo, A; Srivastava, R S; Misra, R D K

2007-03-01

Superparamagnetic nickel ferrite nanoparticles functionalized with polyvinyl alcohol, polyethylene oxide and polymethacrylic acid (PMAA) polymers and subsequently conjugated with doxorubicin anti-cancer drug are studied for their use as a magnetic carrier for drug delivery. Fourier transform infrared spectroscopy enabled examination of the ability of the nanoparticles to be functionalized with polymers and conjugated with doxorubicin drug. The functionalized polymer-coated nanocrystalline nickel ferrites retain the magnetic characteristics of non-functionalized nanocrystalline nickel ferrites (superparamagnetism, absence of hysteresis, remanence and coercivity at room temperature), encouraging their application as a magnetic carrier for drug delivery. The PMAA-coated nanoferrites are demonstrated as being a potentially superior magnetically targeted drug carrier based on FTIR results and drug release kinetics in the absence and presence of an external magnetic field.

Recent advances in polymer solar cells: realization of high device performance by incorporating water/alcohol-soluble conjugated polymers as electrode buffer layer.

PubMed

He, Zhicai; Wu, Hongbin; Cao, Yong

2014-02-01

This Progress Report highlights recent advances in polymer solar cells with special attention focused on the recent rapid-growing progress in methods that use a thin layer of alcohol/water-soluble conjugated polymers as key component to obtain optimized device performance, but also discusses novel materials and device architectures made by major prestigious institutions in this field. We anticipate that due to drastic improvements in efficiency and easy utilization, this method opens up new opportunities for PSCs from various material systems to improve towards 10% efficiency, and many novel device structures will emerge as suitable architectures for developing the ideal roll-to-roll type processing of polymer-based solar cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of disorder on the photoinduced excitations in phenyl substituted polythiophenes

NASA Astrophysics Data System (ADS)

Brabec, Christoph J.; Winder, Christoph; Scharber, Markus C.; Sariciftci, N. Serdar; Hummelen, Jan C.; Svensson, Mattias; Andersson, Mats R.

2001-10-01

Regioregular poly(3-(4'-(1″,4″,7″-trioxaoctyl)phenyl)thiophenes) (PEOPTs) exhibit interesting properties for the use in polymer electronics. Exposing thin films of the amorphous, disordered phase (orange phase) of the "as prepared" polymer to chloroform vapor or annealing them by heat treatment results in a redshift of the absorption maximum due to the formation of nanocrystals in an ordered phase (blue phase). As such, PEOPT thus is a very interesting conjugated polymeric material, which exhibits two different phases with well-defined order/disorder characters on one-and-the-same material. This property opens up the unique possibility to investigate the role of order/disorder on the photoexcited pattern without being obscured by the differences in chemical structure by using different materials with different crystallinity. The fact, that blue phase PEOPT exhibits absorption edges at relatively low energies around 1.8 eV, thereby demonstrating an enhanced spectral absorption range as compared to the orange phase, makes them attractive for use in photodiodes and solar cells as well. The photoinduced charge generation efficiency in both phases of PEOPT is significantly enhanced by the addition of a strong electron acceptor such as fullerene C60, as observed by quenching of the luminescence and by photoinduced absorption measurements in the infrared and uv-visible regime. The average number and the lifetime of photoinduced carriers in composites of PEOPT with a methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) are found to depend on the crystallinity of PEOPT in thin films, which gives rise to charged photoexcitations delocalized between polymer chains. Stronger bimolecular recombination in composites of the blue phase PEOPT with PCBM is observed as compared to the orange phase PEOPT/PCBM films. The origin of this enhanced recombination is found to be related to the hole mobility of the polymer.

Diketopyrrolopyrrole Polymers with Thienyl and Thiazolyl Linkers for Application in Field-Effect Transistors and Polymer Solar Cells.

PubMed

Yu, Yaping; Wu, Yang; Zhang, Andong; Li, Cheng; Tang, Zheng; Ma, Wei; Wu, Yonggang; Li, Weiwei

2016-11-09

Conjugated polymers consisting of diketopyrrolopyrrole (DPP) units have been successfully applied in field-effect transistors (FETs) and polymer solar cells (PSCs), while most of the DPP polymers were designed as symmetric structures containing identical aromatic linkers. In this manuscript, we design a new asymmetric DPP polymer with varied aromatic linkers in the backbone for application in FETs and PSCs. The designation provides the chance to finely adjust the energy levels of conjugated polymers so as to influence the device performance. The asymmetric polymer exhibits highly crystalline properties, high hole mobilities of 3.05 cm 2 V -1 s -1 in FETs, and a high efficiency of 5.9% in PSCs with spectra response from 300 to 850 nm. Morphology investigation demonstrates that the asymmetric polymer has a large crystal domain in blended thin films, indicating that the solar cell performance can be further enhanced by optimizing the microphase separation. The study reveals that the asymmetric design via adjusting the aromatic linkers in DPP polymers is a useful route toward flexible electronic devices.

Broadband optical limiting and nonlinear optical absorption properties of a novel hyperbranched conjugated polymer

NASA Astrophysics Data System (ADS)

Li, Chao; Liu, Chunling; Li, Quanshui; Gong, Qihuang

2004-12-01

The nonlinear transmittance of a novel hyperbranched conjugated polymer named DMA-HPV has been measured in CHCl 3 solution using a nanosecond optical parametric oscillator. DMA-HPV shows excellent optical limiting performance in the visible region from 490 to 610 nm. An explanation based on the combination of two-photon absorption and reverse saturable absorption was proposed for its huge and broadband nonlinear optical absorption.

Exploring Novel Spintronic Responses from Advanced Functional Organic Materials

DTIC Science & Technology

2015-08-13

optical properties of different organic molecules, mesogenics and conjugated polymers, mainly poly(3-alkylthiophene)s, have been investigated by Faraday ...of organic media we focused in our part of the project on studies of the Faraday rotation of an array of organic molecules and conjugated polymers...difficult to measure. However, χeem is easy accessible from Faraday rotation measurements. Faraday rotation, the rotation of the plane of polarization

Rational Design of Porous Conjugated Polymers and Roles of Residual Palladium for Photocatalytic Hydrogen Production.

PubMed

Li, Lianwei; Cai, Zhengxu; Wu, Qinghe; Lo, Wai-Yip; Zhang, Na; Chen, Lin X; Yu, Luping

2016-06-22

Developing highly efficient photocatalyts for water splitting is one of the grand challenges in solar energy conversion. Here, we report the rational design and synthesis of porous conjugated polymer (PCP) that photocatalytically generates hydrogen from water splitting. The design mimics natural photosynthetics systems with conjugated polymer component to harvest photons and the transition metal part to facilitate catalytic activities. A series of PCPs have been synthesized with different light harvesting chromophores and transition metal binding bipyridyl (bpy) sites. The photocatalytic activity of these bpy-containing PCPs can be greatly enhanced due to the improved light absorption, better wettability, local ordering structure, and the improved charge separation process. The PCP made of strong and fully conjugated donor chromophore DBD (M4) shows the highest hydrogen production rate at ∼33 μmol/h. The results indicate that copolymerization between a strong electron donor and weak electron acceptor into the same polymer chain is a useful strategy for developing efficient photocatalysts. This study also reveals that the residual palladium in the PCP networks plays a key role for the catalytic performance. The hydrogen generation activity of PCP photocatalyst can be further enhanced to 164 μmol/h with an apparent quantum yield of 1.8% at 350 nm by loading 2 wt % of extra platinum cocatalyst.

Phase-breaking effect on polaron transport in organic conjugated polymers

DOE PAGES

Meng, Ruixuan; Yin, Sun; Zheng, Yujun; ...

2017-06-15

Despite intense investigations and many accepted viewpoints on theory and experiment, the coherent and incoherent carrier transport in organic semiconductors remains an unsettled topic due to the strong electron-phonon coupling. Based on the tight-binding Su-Schrieffer-Heeger (SSH) model combined with a non-adiabatic dynamics method, we study the effect of phase-breaking on polaron transport by introducing a group of phase-breaking factors into π-electron wave-functions in organic conjugated polymers. Two approaches are applied: the modification of the transfer integral and the phase-breaking addition to the wave-function. Within the former, it is found that a single site phase-breaking can trap a polaron. However, withmore » a larger regular phase-breaking a polaron becomes more delocalized and lighter. Additionally, a group of disordered phase-breaking factors can make the polaron disperse in transport process. Within the latter approach, we show that the phase-breaking can render the delocalized state in valence band discrete and the state in the gap more localized. Consequently, the phase-breaking frequency and intensity can reduce the stability of a polaron. Furthermore, the phase-breaking in organic systems is the main factor that degrades the coherent transport and destroys the carrier stability.« less

Trojan horses and guided missiles: targeted therapies in the war on arthritis.

PubMed

Ferrari, Mathieu; Onuoha, Shimobi C; Pitzalis, Costantino

2015-06-01

Despite major advances in the treatment of rheumatoid arthritis (RA) led by the success of biologic therapies, the lack of response to therapy in a proportion of patients, as well as therapy discontinuation owing to systemic toxicity, are still unsolved issues. Unchecked RA might develop into progressive structural joint damage, loss of function and long-term disability, disorders which are associated with a considerable health-economic burden. Therefore, new strategies are required to actively target and deliver therapeutic agents to disease sites in order to promote in situ activity and decrease systemic toxicity. Polymer-drug conjugates can improve the pharmacokinetics of therapeutic agents, conferring desirable properties such as increased solubility and tissue penetration at sites of active disease. Additionally, nanotechnology is an exciting modality in which drugs are encapsulated to protect them from degradation or early activation in the circulation, as well as to reduce systemic toxicity. Together with the targeting capacity of antibodies and site-specific peptides, these approaches will facilitate selective accumulation of therapeutic agents in the inflamed synovium, potentially improving drug efficacy at disease sites without affecting healthy tissues. This Review aims to summarize key developments in the past 5 years in polymer conjugation, nanoparticulate drug delivery and antibody or peptide-based targeting--strategies that might constitute the platform for the next generation of RA therapeutics.

Phase-breaking effect on polaron transport in organic conjugated polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Ruixuan; Yin, Sun; Zheng, Yujun

Despite intense investigations and many accepted viewpoints on theory and experiment, the coherent and incoherent carrier transport in organic semiconductors remains an unsettled topic due to the strong electron-phonon coupling. Based on the tight-binding Su-Schrieffer-Heeger (SSH) model combined with a non-adiabatic dynamics method, we study the effect of phase-breaking on polaron transport by introducing a group of phase-breaking factors into π-electron wave-functions in organic conjugated polymers. Two approaches are applied: the modification of the transfer integral and the phase-breaking addition to the wave-function. Within the former, it is found that a single site phase-breaking can trap a polaron. However, withmore » a larger regular phase-breaking a polaron becomes more delocalized and lighter. Additionally, a group of disordered phase-breaking factors can make the polaron disperse in transport process. Within the latter approach, we show that the phase-breaking can render the delocalized state in valence band discrete and the state in the gap more localized. Consequently, the phase-breaking frequency and intensity can reduce the stability of a polaron. Furthermore, the phase-breaking in organic systems is the main factor that degrades the coherent transport and destroys the carrier stability.« less

Bioconjugation and Applications of Amino Functional Fluorescence Polymers.

PubMed

Geyik, Caner; Guler, Emine; Gumus, Zinar Pinar; Barlas, Firat Baris; Akbulut, Huseyin; Demirkol, Dilek Odaci; Timur, Suna; Yagci, Yusuf

2017-03-01

Synthesis and novel applications of biofunctional polymers for diagnosis and therapy are promising area involving various research domains. Herein, three fluorescent polymers, poly(p-phenylene-co-thiophene), poly(p-phenylene), and polythiophene with amino groups (PPT-NH 2 , PPP-NH 2 , and PT-NH 2 , respectively) are synthesized and investigated for cancer cell targeted imaging, drug delivery, and radiotherapy. Polymers are conjugated to anti-HER2 antibody for targeted imaging studies in nontoxic concentrations. Three cell lines (A549, Vero, and HeLa) with different expression levels of HER2 are used. In a model of HER2 expressing cell line (A549), radiotherapy experiments are carried out and results show that all three polymers increase the efficacy of radiotherapy. This effect is even more increased when conjugated to anti-HER2. In the second part of this work, one of the selected polymers (PT-NH 2 ) is conjugated with a drug model; methotrexate via pH responsive hydrazone linkage and a drug carrier property of PT-NH 2 is demonstrated on neuroblastoma (SH-SY5Y) cell model. Our results indicate that, PPT-NH 2 , PPP-NH 2 , and PT-NH 2 have a great potential as biomaterials for various bioapplications in cancer research. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bipolar and Unipolar Silylene-Diphenylene σ-π Conjugated Polymer Route for Highly Efficient Electrophosphorescence

NASA Astrophysics Data System (ADS)

Chang, Yao-Tang; Sharma, Sunil; Hung, Miao-Ken; Lee, Yu-Hsuan; Chen, Show-An

2016-12-01

σ-π conjugated polymer strategy is proposed for designing electroluminescent host polymers with silylene-diphenylene as the backbone repeat unit giving a high triplet energy (ET = 2.67 eV). By incorporation of high ET (3.0 eV) electron (oxadiazole, OXD) and hole (triphenyl amine, TPA) transport moieties, or TPA alone (in this case, the main chain acts as electron transport channel) as side arms on the silylene, the high ET bipolar and unipolar polymers are formed, allowing a use of iridium green phosphor (Ir(ppy)2(acac), Ir-G) (ET = 2.40 eV) as the dopant. The matching of energy levels of the dopant with the hosts, leading to charge trapping into it; and singlets and triplets of the exciplex and excimer can be harvested via energy transfer to the dopant. Using these host-guest systems as the emitting layer, chlorinated indium-tin-oxide (Cl-ITO) as the anode, and benzimidazole derivative (TPBI) as the electron transport layer, this two-layer device gives the high luminance efficiency 80.1 cd/A and external quantum efficiency 21.2%, which is the best among the report values for polymer light emitting diode (PLED) in the literatures. This example manifests that σ-π conjugated polymer strategy is a promising route for designing polymer host for efficient electrophosphorescence.

Bipolar and Unipolar Silylene-Diphenylene σ-π Conjugated Polymer Route for Highly Efficient Electrophosphorescence

PubMed Central

Chang, Yao-Tang; Sharma, Sunil; Hung, Miao-Ken; Lee, Yu-Hsuan; Chen, Show-An

2016-01-01

σ-π conjugated polymer strategy is proposed for designing electroluminescent host polymers with silylene-diphenylene as the backbone repeat unit giving a high triplet energy (ET = 2.67 eV). By incorporation of high ET (3.0 eV) electron (oxadiazole, OXD) and hole (triphenyl amine, TPA) transport moieties, or TPA alone (in this case, the main chain acts as electron transport channel) as side arms on the silylene, the high ET bipolar and unipolar polymers are formed, allowing a use of iridium green phosphor (Ir(ppy)2(acac), Ir-G) (ET = 2.40 eV) as the dopant. The matching of energy levels of the dopant with the hosts, leading to charge trapping into it; and singlets and triplets of the exciplex and excimer can be harvested via energy transfer to the dopant. Using these host-guest systems as the emitting layer, chlorinated indium-tin-oxide (Cl-ITO) as the anode, and benzimidazole derivative (TPBI) as the electron transport layer, this two-layer device gives the high luminance efficiency 80.1 cd/A and external quantum efficiency 21.2%, which is the best among the report values for polymer light emitting diode (PLED) in the literatures. This example manifests that σ-π conjugated polymer strategy is a promising route for designing polymer host for efficient electrophosphorescence. PMID:27910921

Thermoelectric plastics: from design to synthesis, processing and structure–property relationships

PubMed Central

Kroon, Renee; Mengistie, Desalegn Alemu; Kiefer, David; Hynynen, Jonna; Ryan, Jason D.; Yu, Liyang

2016-01-01

Thermoelectric plastics are a class of polymer-based materials that combine the ability to directly convert heat to electricity, and vice versa, with ease of processing. Potential applications include waste heat recovery, spot cooling and miniature power sources for autonomous electronics. Recent progress has led to surging interest in organic thermoelectrics. This tutorial review discusses the current trends in the field with regard to the four main building blocks of thermoelectric plastics: (1) organic semiconductors and in particular conjugated polymers, (2) dopants and counterions, (3) insulating polymers, and (4) conductive fillers. The design and synthesis of conjugated polymers that promise to show good thermoelectric properties are explored, followed by an overview of relevant structure–property relationships. Doping of conjugated polymers is discussed and its interplay with processing as well as structure formation is elucidated. The use of insulating polymers as binders or matrices is proposed, which permit the adjustment of the rheological and mechanical properties of a thermoelectric plastic. Then, nanocomposites of conductive fillers such as carbon nanotubes, graphene and inorganic nanowires in a polymer matrix are introduced. A case study examines poly(3,4-ethylenedioxythiophene) (PEDOT) based materials, which up to now have shown the most promising thermoelectric performance. Finally, a discussion of the advantages provided by bulk architectures e.g. for wearable applications highlights the unique advantages that thermoelectric plastics promise to offer. PMID:27385496

PEG-poly(amino acid) block copolymer micelles for tunable drug release.

PubMed

Ponta, Andrei; Bae, Younsoo

2010-11-01

To achieve tunable pH-dependent drug release in tumor tissues. Poly(ethylene glycol)-poly(aspartic acid) [PEG-p(Asp)] containing 12 kDa PEG and pAsp (5, 15, and 35 repeating units) were prepared. Hydrazide linkers with spacers [glycine (Gly) and 4-aminobenzoate (Abz)] were introduced to PEG-p(Asp), followed by drug conjugation [doxorubicin (DOX)]. The block copolymer-drug conjugates were either reconstituted or dialyzed in aqueous solutions to prepare micelles. Drug release patterns were observed under sink conditions at pH 5.0 and 7.4, 37°C, for 48 h. A collection of six block copolymers with different chain lengths and spacers was synthesized. Drug binding yields were 13-43.6%. The polymer-drug conjugates formed <50 nm polymer micelles irrespective of polymer compositions. Gly-introduced polymer micelles showed marginal change in particle size (40 ± 10 nm), while the size of Abz-micelles increased gradually from 10 to 40 nm as the polymer chain lengths increased. Drug release patterns of both Gly and Abz micelles were pH-dependent and tunable. The spacers appear to play a crucial role in controlling drug release and stability of polymer micelles in combination with block copolymer chain lengths. A drug delivery platform for tunable drug release was successfully developed with polymer micelles possessing spacer-modified hydrazone drug-binding linkers.

Naphthodipyrrolidone (NDP) based conjugated polymers with high electron mobility and ambipolar transport properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Haichang; Zhang, Shuo; Mao, Yifan

Two novel donor–acceptor π-conjugated polymers based on naphthodipyrrolidone (NDP) were synthesized and characterized. The polymers possess low band gaps and suitable molecular orbital levels as ambipolar semiconductors. The thin film organic field effect transistor of NDP polymers exhibited ambipolar transport properties with a high electron mobility up to 0.67 cm 2 V –1 s –1. The grazing-incidence wide-angle X-ray scattering (GIWAXS) studies demonstrated that the polymer molecules pack into a long-range-ordered lamellar structure with isotropically oriented crystalline domains. Thermal annealing promoted edge-on lamellar stacking as evidenced by the increased diffraction intensity along the out-of-plane direction. In conclusion, the polymer withmore » NDP and bithiophene units achieved the best edge-on lamellar stacking after thermal annealing, which yielded the best electron transport performance in this work.« less

Naphthodipyrrolidone (NDP) based conjugated polymers with high electron mobility and ambipolar transport properties

DOE PAGES

Zhang, Haichang; Zhang, Shuo; Mao, Yifan; ...

2017-05-12

Two novel donor–acceptor π-conjugated polymers based on naphthodipyrrolidone (NDP) were synthesized and characterized. The polymers possess low band gaps and suitable molecular orbital levels as ambipolar semiconductors. The thin film organic field effect transistor of NDP polymers exhibited ambipolar transport properties with a high electron mobility up to 0.67 cm 2 V –1 s –1. The grazing-incidence wide-angle X-ray scattering (GIWAXS) studies demonstrated that the polymer molecules pack into a long-range-ordered lamellar structure with isotropically oriented crystalline domains. Thermal annealing promoted edge-on lamellar stacking as evidenced by the increased diffraction intensity along the out-of-plane direction. In conclusion, the polymer withmore » NDP and bithiophene units achieved the best edge-on lamellar stacking after thermal annealing, which yielded the best electron transport performance in this work.« less

Water/alcohol soluble conjugated polymers as highly efficient electron transporting/injection layer in optoelectronic devices.

PubMed

Huang, Fei; Wu, Hongbin; Cao, Yong

2010-07-01

Water/alcohol soluble conjugated polymers (WSCPs) can be processed from water or other polar solvents, which offer good opportunities to avoid interfacial mixing upon fabrication of multilayer polymer optoelectronic devices by solution processing, and can dramatically improve charge injection from high work-function metal cathode resulting in greatly enhancement of the device performance. In this critical review, the authors provide a brief review of recent developments in this field, including the materials design, functional principles, and their unique applications as interface modification layer in solution-processable multilayer optoelectronic devices (135 references).

Threshold-like complexation of conjugated polymers with small molecule acceptors in solution within the neighbor-effect model.

PubMed

Sosorev, Andrey Yu; Parashchuk, Olga D; Zapunidi, Sergey A; Kashtanov, Grigoriy S; Golovnin, Ilya V; Kommanaboyina, Srikanth; Perepichka, Igor F; Paraschuk, Dmitry Yu

2016-02-14

In some donor-acceptor blends based on conjugated polymers, a pronounced charge-transfer complex (CTC) forms in the electronic ground state. In contrast to small-molecule donor-acceptor blends, the CTC concentration in polymer:acceptor solution can increase with the acceptor content in a threshold-like way. This threshold-like behavior was earlier attributed to the neighbor effect (NE) in the polymer complexation, i.e., next CTCs are preferentially formed near the existing ones; however, the NE origin is unknown. To address the factors affecting the NE, we record the optical absorption data for blends of the most studied conjugated polymers, poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and poly(3-hexylthiophene) (P3HT), with electron acceptors of fluorene series, 1,8-dinitro-9,10-antraquinone (), and 7,7,8,8-tetracyanoquinodimethane () in different solvents, and then analyze the data within the NE model. We have found that the NE depends on the polymer and acceptor molecular skeletons and solvent, while it does not depend on the acceptor electron affinity and polymer concentration. We conclude that the NE operates within a single macromolecule and stems from planarization of the polymer chain involved in the CTC with an acceptor molecule; as a result, the probability of further complexation with the next acceptor molecules at the adjacent repeat units increases. The steric and electronic microscopic mechanisms of NE are discussed.

Spectral diffusion in poly(para-phenylene)-type polymers with different energetic disorder

NASA Astrophysics Data System (ADS)

Hoffmann, Sebastian T.; Bässler, Heinz; Koenen, Jan-Moritz; Forster, Michael; Scherf, Ullrich; Scheler, Esther; Strohriegl, Peter; Köhler, Anna

2010-03-01

We have employed quasicontinuous fluorescence and phosphorescence spectroscopy within a temperature range between 10 and 500 K to monitor the spectral diffusion of singlet and triplet excitons in a series of π -conjugated polymers. We investigated (i) how spectral diffusion is controlled by the degree of energetic disorder present in the amorphous film (that is reflected by the inhomogeneous broadening of the photoluminescence spectra) and (ii) how this process depends on the range of the electronic coupling (by comparing singlet exciton diffusion via long-range Förster transfer against triplet exciton diffusion by short-range Dexter transfer). For singlets, we find that the fluorescence spectra bear out a bathochromic shift upon cooling the sample down to a critical temperature below which the shift saturates. This bathochromic shift is a signature of spectral relaxation. Random-walk theory applied to excitation transport within a Gaussian density-of-states distribution is both necessary and sufficient to rationalize the experimental results in a quantitative fashion. The same behavior is observed for triplets in weakly disordered systems, such as in a polymer containing platinum in the main chain and a ladder-type polyphenylene. In contrast we observe a hypsochromic shift of the phosphorescence spectra below a characteristic temperature for triplets in systems with at least moderate energetic disorder. The hypsochromic shift proves that triplet exciton relaxation becomes frustrated because thermally activated exciton jumps that otherwise promote spectral diffusion become progressively frozen out. The frustration effect is controlled by the jump distance and thus it is specific for triplet excitations that migrate via short-range coupling among strongly localized states as compared to singlet excitons.

ATP-Responsive and Near-Infrared-Emissive Nanocarriers for Anticancer Drug Delivery and Real-Time Imaging.

PubMed

Qian, Chenggen; Chen, Yulei; Zhu, Sha; Yu, Jicheng; Zhang, Lei; Feng, Peijian; Tang, Xin; Hu, Quanyin; Sun, Wujin; Lu, Yue; Xiao, Xuanzhong; Shen, Qun-Dong; Gu, Zhen

2016-01-01

Stimuli-responsive and imaging-guided drug delivery systems hold vast promise for enhancement of therapeutic efficacy. Here we report an adenosine-5'-triphosphate (ATP)-responsive and near-infrared (NIR)-emissive conjugated polymer-based nanocarrier for the controlled release of anticancer drugs and real-time imaging. We demonstrate that the conjugated polymeric nanocarriers functionalized with phenylboronic acid tags on surface as binding sites for ATP could be converted to the water-soluble conjugated polyelectrolytes in an ATP-rich environment, which promotes the disassembly of the drug carrier and subsequent release of the cargo. In vivo studies validate that this formulation exhibits promising capability for inhibition of tumor growth. We also evaluate the metabolism process by monitoring the fluorescence signal of the conjugated polymer through the in vivo NIR imaging.

Emission turn-on and solubility turn-off in conjugated polymers: one- and two-photon-induced removal of fluorescence-quenching solubilizing groups.

PubMed

Schelkle, Korwin M; Becht, Steffy; Faraji, Shirin; Petzoldt, Martin; Müllen, Klaus; Buckup, Tiago; Dreuw, Andreas; Motzkus, Marcus; Hamburger, Manuel

2015-01-01

The synthesis of highly efficient two-photon uncaging groups and their potential use in functional conjugated polymers for post-polymerization modification are reported. Careful structural design of the employed nitrophenethyl caging groups allows to efficiently induce bond scission by a two-photon process through a combination of exceptionally high two-photon absorption cross-sections and high reaction quantum yields. Furthermore, π-conjugated polyfluorenes are functionalized with these photocleavable side groups and it is possible to alter their emission properties and solubility behavior by simple light irradiation. Cleavage of side groups leads to a turn-on of the fluorescence while solubility of the π-conjugated materials is drastically reduced. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lower Critical Solution Temperature (LCST) and drug conjugation of polyacetal

NASA Astrophysics Data System (ADS)

de Silva, Chathuranga; Samanta, Sanjoy; Leophairatana, Porakrit; Koberstein, Jeffrey

There has been an increasing focus in polymer research for materials that can efficiently deliver therapeutics to a pre-identified solid tumor target. Due to their unique properties, stimuli responsive polymers (SRPs) have been of particular interest. One such novel SRP is a polyacetal-based copolymer (PAC). PAC shows a remarkable temperature response (LCST) that is linearly dependent on composition. Here, we discuss the fundamental physical origins of this LCST behavior, exhibited by this polymer. Our results indicate that the observed LCST scales linearly with the number of carbon and oxygen atoms in the polymer repeat units, allowing for precise control over the LCST. We design PAC to include cancer therapeutics in its polymer-backbone, utilizing strategies to modify step-growth polymerization to obtain, for the first time, temperature-responsive main-chain drug conjugates. The temperature response in these main-chain drug conjugates allow for effective delivery of therapeutics to the tumor site, followed by acid-hydrolysis in acidic local tumor environments, to release pristine therapeutics directly at the tumor site. Due to these reasons, we foresee PAC to be in the forefront of soft-matter SRP drug-delivery systems.

Electrodeposition and Screening of Photoelectrochemical Activity in Conjugated Polymers Using Scanning Electrochemical Cell Microscopy.

PubMed

Aaronson, Barak D B; Garoz-Ruiz, Jesus; Byers, Joshua C; Colina, Alvaro; Unwin, Patrick R

2015-11-24

A number of renewable energy systems require an understanding and correlation of material properties and photoelectrochemical activity on the micro to nanoscale. Among these, conducting polymer electrodes continue to be important materials. In this contribution, an ultrasensitive scanning electrochemical cell microscopy (SECCM) platform is used to electrodeposit microscale thin films of poly(3-hexylthiophene) (P3HT) on an optically transparent gold electrode and to correlate the morphology (film thickness and structural order) with photoactivity. The electrochemical growth of P3HT begins with a thin ordered film up to 10 nm thick, after which a second more disordered film is deposited, as revealed by micro-Raman spectroscopy. A decrease in photoactivity for the thicker films, measured in situ immediately following film deposition, is attributed to an increase in bulk film disorder that limits charge transport. Higher resolution ex situ SECCM phototransient measurements, using a smaller diameter probe, show local variations in photoactivity within a given deposit. Even after aging, thinner, more ordered regions within a deposit exhibit sustained enhanced photocurrent densities compared to areas where the film is thicker and more disordered. The platform opens up new possibilities for high-throughput combinatorial correlation studies, by allowing materials fabrication and high spatial resolution probing of processes in photoelectrochemical materials.

PPV-Based Conjugated Polymer Nanoparticles as a Versatile Bioimaging Probe: A Closer Look at the Inherent Optical Properties and Nanoparticle-Cell Interactions.

PubMed

Peters, Martijn; Zaquen, Neomy; D'Olieslaeger, Lien; Bové, Hannelore; Vanderzande, Dirk; Hellings, Niels; Junkers, Thomas; Ethirajan, Anitha

2016-08-08

Conjugated polymers have attracted significant interest in the bioimaging field due to their excellent optical properties and biocompatibility. Tailor-made poly(p-phenylenevinylene) (PPV) conjugated polymer nanoparticles (NPs) are in here described. Two different nanoparticle systems using poly[2-methoxy-5-(3',7'-dimethoxyoctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and a functional statistical copolymer 2-(5'-methoxycarbonylpentyloxy)-5-methoxy-1,4-phenylenevinylene (CPM-MDMO-PPV), containing ester groups on the alkoxy side chains, were synthesized by combining miniemulsion and solvent evaporation processes. The hydrolysis of ester groups into carboxylic acid groups on the CPM-MDMO-PPV NPs surface allows for biomolecule conjugation. The NPs exhibited excellent optical properties with a high fluorescent brightness and photostability. The NPs were in vitro tested as potential fluorescent nanoprobes for studying cell populations within the central nervous system. The cell studies demonstrated biocompatibility and surface charge dependent cellular uptake of the NPs. This study highlights that PPV-derivative based particles are a promising bioimaging probe and can cater potential applications in the field of nanomedicine.

Polymeric anticancer drugs with pH-controlled activation.

PubMed

Ulbrich, Karel; Subr, Vladimír

2004-04-23

Use of macromolecular water-soluble carriers of anti-cancer drugs represents a promising approach to cancer therapy. Release of drugs from the carrier system is a prerequisite for therapeutic activity of most macromolecular anti-cancer conjugates. Incorporation of acid-sensitive spacers between the drug and carrier enables release of an active drug from the carrier in a tumor tissue, either in slightly acidic extracellular fluids or, after endocytosis, in endosomes or lysosomes of cancer cells. This paper reviews advances in development and study of properties of various acid-sensitive macromolecular drug delivery systems, starting from simple polymer-drug conjugates to ending with site-specific antibody-targeted polymer-drug conjugates.

Deep-Blue Fluorescent Particles via Microwave Heating of Polyacrylonitrile Dispersions.

PubMed

Go, Dennis; Jurásková, Alena; Hoffmann, Andreas; Kapiti, Gent; Kuehne, Alexander J C

2017-03-01

This study presents a new method to produce fluorescent particles. Established methods are based on the incorporation of conjugated dye molecules into dielectric polymer matrices or preparation of colloids, which are composed of fluorescent conjugated polymer. By contrast, this study presents a method where dielectric polyacrylonitrile is exposed to microwave radiation leading to an intramolecular cyclization reaction producing π-conjugated segments, which fluoresce blue. During this conversion, the particles shrink in diameter but as an ensemble they retain their monodispersity. This work investigates the optimal reaction conditions and characterizes the optical properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theory of optical transitions in π-conjugated macrocycles

NASA Astrophysics Data System (ADS)

Marcus, Max; Coonjobeeharry, Jaymee; Barford, William

2016-04-01

We describe a theoretical and computational investigation of the optical properties of π-conjugated macrocycles. Since the low-energy excitations of these systems are Frenkel excitons that couple to high-frequency dispersionless phonons, we employ the quantized Frenkel-Holstein model and solve it via the density matrix renormalization group (DMRG) method. First we consider optical emission from perfectly circular systems. Owing to optical selection rules, such systems radiate via two mechanisms: (i) within the Condon approximation, by thermally induced emission from the optically allowed j = ± 1 states and (ii) beyond the Condon approximation, by emission from the j = 0 state via coupling with a totally non-symmetric phonon (namely, the Herzberg-Teller effect). Using perturbation theory, we derive an expression for the Herzberg-Teller correction and show via DMRG calculations that this expression soon fails as ħ ω/J and the size of the macrocycle increase. Next, we consider the role of broken symmetry caused by torsional disorder. In this case the quantum number j no longer labels eigenstates of angular momentum, but instead labels localized local exciton groundstates (LEGSs) or quasi-extended states (QEESs). As for linear polymers, LEGSs define chromophores, with the higher energy QEESs being extended over numerous LEGSs. Within the Condon approximation (i.e., neglecting the Herzberg-Teller correction) we show that increased disorder increases the emissive optical intensity, because all the LEGSs are optically active. We next consider the combined role of broken symmetry and curvature, by explicitly evaluating the Herzberg-Teller correction in disordered systems via the DMRG method. The Herzberg-Teller correction is most evident in the emission intensity ratio, I00/I01. In the Condon approximation I00/I01 is a constant function of curvature, whereas in practice it vanishes for closed rings and only approaches a constant in the limit of vanishing curvature. We calculate the optical spectra of a model system, cyclo-poly(para-phenylene ethynylene), for different amounts of torsional disorder within and beyond the Condon approximation. We show how broken symmetry and the Herzberg-Teller effect explain the spectral features. The Herzberg-Teller correction to the 0-1 emission vibronic peak is always significant. Finally, we note the qualitative similarities between the optical properties of conformationally disordered linear polymers and macrocycles in the limit of sufficiently large disorder, because in both cases they are determined by the optical properties of curved chromophores.

Poly(2-oxazoline)s as Polymer Therapeutics

PubMed Central

Luxenhofer, Robert; Han, Yingchao; Schulz, Anita; Tong, Jing; He, Zhijian; Kabanov, Alexander V.; Jordan, Rainer

2013-01-01

Poly(2-oxazoline)s (POx) are currently discussed as an upcoming platform for biomaterials design and especially for polymer therapeutics. POx meets several requirements needed for the development of next-generation polymer therapeutics such as biocompatibility, high modulation of solubility, variation of size, architecture as well as chemical functionality. Although in the early 1990s first and promising POx-based systems were presented but the field lay dormant for almost two decades. Only very recently, POx based polymer therapeutics came back into the focus of very intensive research. In this review, we give an overview on the chemistry and physicochemical properties of POx and summarize the research of POx-protein conjugates, POx-drug conjugates, POx-based polyplexes and POx micelles for drug delivery. PMID:22865555

iBodies: Modular Synthetic Antibody Mimetics Based on Hydrophilic Polymers Decorated with Functional Moieties.

PubMed

Šácha, Pavel; Knedlík, Tomáš; Schimer, Jiří; Tykvart, Jan; Parolek, Jan; Navrátil, Václav; Dvořáková, Petra; Sedlák, František; Ulbrich, Karel; Strohalm, Jiří; Majer, Pavel; Šubr, Vladimír; Konvalinka, Jan

2016-02-12

Antibodies are indispensable tools for biomedicine and anticancer therapy. Nevertheless, their use is compromised by high production costs, limited stability, and difficulty of chemical modification. The design and preparation of synthetic polymer conjugates capable of replacing antibodies in biomedical applications such as ELISA, flow cytometry, immunocytochemistry, and immunoprecipitation is reported. The conjugates, named "iBodies", consist of an HPMA copolymer decorated with low-molecular-weight compounds that function as targeting ligands, affinity anchors, and imaging probes. We prepared specific conjugates targeting several proteins with known ligands and used these iBodies for enzyme inhibition, protein isolation, immobilization, quantification, and live-cell imaging. Our data indicate that this highly modular and versatile polymer system can be used to produce inexpensive and stable antibody substitutes directed toward virtually any protein of interest with a known ligand. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

iBodies: Modular Synthetic Antibody Mimetics Based on Hydrophilic Polymers Decorated with Functional Moieties

PubMed Central

Šácha, Pavel; Knedlík, Tomáš; Schimer, Jiří; Tykvart, Jan; Parolek, Jan; Navrátil, Václav; Dvořáková, Petra; Sedlák, František; Ulbrich, Karel; Strohalm, Jiří; Majer, Pavel

2016-01-01

Abstract Antibodies are indispensable tools for biomedicine and anticancer therapy. Nevertheless, their use is compromised by high production costs, limited stability, and difficulty of chemical modification. The design and preparation of synthetic polymer conjugates capable of replacing antibodies in biomedical applications such as ELISA, flow cytometry, immunocytochemistry, and immunoprecipitation is reported. The conjugates, named “iBodies”, consist of an HPMA copolymer decorated with low‐molecular‐weight compounds that function as targeting ligands, affinity anchors, and imaging probes. We prepared specific conjugates targeting several proteins with known ligands and used these iBodies for enzyme inhibition, protein isolation, immobilization, quantification, and live‐cell imaging. Our data indicate that this highly modular and versatile polymer system can be used to produce inexpensive and stable antibody substitutes directed toward virtually any protein of interest with a known ligand. PMID:26749427

Conjugated Microporous Polymers for Heterogeneous Catalysis.

PubMed

Zhou, Yun-Bing; Zhan, Zhuang-Ping

2018-01-04

Conjugated microporous polymers (CMPs) are a class of crosslinked polymers that combine permanent micropores with π-conjugated skeletons and possess three-dimensional (3D) networks. Compared with conventional materials such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), CMPs usually have superior chemical and thermal stability. CMPs have made significant progress in heterogeneous catalysis in the past seven years. With a bottom-up strategy, catalytic moieties can be directly introduced into in the framework to produce heterogeneous CMP catalysts. Higher activity, stability, and selectivity can be obtained with heterogeneous CMP catalysts in comparison with their homogeneous analogs. In addition, CMP catalysts can be easily isolated and recycled. In this review, we focus on CMPs as an intriguing platform for developing various highly efficient and recyclable heterogeneous catalysts in organic reactions. The design, synthesis, and structure of these CMP catalysts are also discussed in this focus review. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light-evoked hyperpolarization and silencing of neurons by conjugated polymers.

PubMed

Feyen, Paul; Colombo, Elisabetta; Endeman, Duco; Nova, Mattia; Laudato, Lucia; Martino, Nicola; Antognazza, Maria Rosa; Lanzani, Guglielmo; Benfenati, Fabio; Ghezzi, Diego

2016-03-04

The ability to control and modulate the action potential firing in neurons represents a powerful tool for neuroscience research and clinical applications. While neuronal excitation has been achieved with many tools, including electrical and optical stimulation, hyperpolarization and neuronal inhibition are typically obtained through patch-clamp or optogenetic manipulations. Here we report the use of conjugated polymer films interfaced with neurons for inducing a light-mediated inhibition of their electrical activity. We show that prolonged illumination of the interface triggers a sustained hyperpolarization of the neuronal membrane that significantly reduces both spontaneous and evoked action potential firing. We demonstrate that the polymeric interface can be activated by either visible or infrared light and is capable of modulating neuronal activity in brain slices and explanted retinas. These findings prove the ability of conjugated polymers to tune neuronal firing and suggest their potential application for the in-vivo modulation of neuronal activity.

Light-evoked hyperpolarization and silencing of neurons by conjugated polymers

PubMed Central

Feyen, Paul; Colombo, Elisabetta; Endeman, Duco; Nova, Mattia; Laudato, Lucia; Martino, Nicola; Antognazza, Maria Rosa; Lanzani, Guglielmo; Benfenati, Fabio; Ghezzi, Diego

2016-01-01

The ability to control and modulate the action potential firing in neurons represents a powerful tool for neuroscience research and clinical applications. While neuronal excitation has been achieved with many tools, including electrical and optical stimulation, hyperpolarization and neuronal inhibition are typically obtained through patch-clamp or optogenetic manipulations. Here we report the use of conjugated polymer films interfaced with neurons for inducing a light-mediated inhibition of their electrical activity. We show that prolonged illumination of the interface triggers a sustained hyperpolarization of the neuronal membrane that significantly reduces both spontaneous and evoked action potential firing. We demonstrate that the polymeric interface can be activated by either visible or infrared light and is capable of modulating neuronal activity in brain slices and explanted retinas. These findings prove the ability of conjugated polymers to tune neuronal firing and suggest their potential application for the in-vivo modulation of neuronal activity. PMID:26940513

Computer-Aided Screening of Conjugated Polymers for Organic Solar Cell: Classification by Random Forest.

PubMed

Nagasawa, Shinji; Al-Naamani, Eman; Saeki, Akinori

2018-05-17

Owing to the diverse chemical structures, organic photovoltaic (OPV) applications with a bulk heterojunction framework have greatly evolved over the last two decades, which has produced numerous organic semiconductors exhibiting improved power conversion efficiencies (PCEs). Despite the recent fast progress in materials informatics and data science, data-driven molecular design of OPV materials remains challenging. We report a screening of conjugated molecules for polymer-fullerene OPV applications by supervised learning methods (artificial neural network (ANN) and random forest (RF)). Approximately 1000 experimental parameters including PCE, molecular weight, and electronic properties are manually collected from the literature and subjected to machine learning with digitized chemical structures. Contrary to the low correlation coefficient in ANN, RF yields an acceptable accuracy, which is twice that of random classification. We demonstrate the application of RF screening for the design, synthesis, and characterization of a conjugated polymer, which facilitates a rapid development of optoelectronic materials.

Solution-processable ambipolar diketopyrrolopyrrole-selenophene polymer with unprecedentedly high hole and electron mobilities.

PubMed

Lee, Junghoon; Han, A-Reum; Kim, Jonggi; Kim, Yiho; Oh, Joon Hak; Yang, Changduk

2012-12-26

There is a fast-growing demand for polymer-based ambipolar thin-film transistors (TFTs), in which both n-type and p-type transistor operations are realized in a single layer, while maintaining simplicity in processing. Research progress toward this end is essentially fueled by molecular engineering of the conjugated backbones of the polymers and the development of process architectures for device fabrication, which has recently led to hole and electron mobilities of more than 1.0 cm(2) V(-1) s(-1). However, ambipolar polymers with even higher performance are still required. By taking into account both the conjugated backbone and side chains of the polymer component, we have developed a dithienyl-diketopyrrolopyrrole (TDPP) and selenophene containing polymer with hybrid siloxane-solubilizing groups (PTDPPSe-Si). A synergistic combination of rational polymer backbone design, side-chain dynamics, and solution processing affords an enormous boost in ambipolar TFT performance, resulting in unprecedentedly high hole and electron mobilities of 3.97 and 2.20 cm(2) V(-1) s(-1), respectively.

Anomalous charge transport in conjugated polymers reveals underlying mechanisms of trapping and percolation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mollinger, Sonya A.; Salleo, Alberto; Spakowitz, Andrew J.

While transport in conjugated polymers has many similarities to that in crystalline inorganic materials, several key differences reveal the unique relationship between the morphology of polymer films and the charge mobility. We develop a model that directly incorporates the molecular properties of the polymer film and correctly predicts these unique transport features. At low degree of polymerization, the increase of the mobility with the polymer chain length reveals trapping at chain ends, and saturation of the mobility at high degree of polymerization results from conformational traps within the chains. Similarly, the inverse field dependence of the mobility reveals that transportmore » on single polymer chains is characterized by the ability of the charge to navigate around kinks and loops in the chain. Lastly, these insights emphasize the connection between the polymer conformations and the transport and thereby offer a route to designing improved device morphologies through molecular design and materials processing.« less

Anomalous charge transport in conjugated polymers reveals underlying mechanisms of trapping and percolation

DOE PAGES

Mollinger, Sonya A.; Salleo, Alberto; Spakowitz, Andrew J.

2016-11-10

While transport in conjugated polymers has many similarities to that in crystalline inorganic materials, several key differences reveal the unique relationship between the morphology of polymer films and the charge mobility. We develop a model that directly incorporates the molecular properties of the polymer film and correctly predicts these unique transport features. At low degree of polymerization, the increase of the mobility with the polymer chain length reveals trapping at chain ends, and saturation of the mobility at high degree of polymerization results from conformational traps within the chains. Similarly, the inverse field dependence of the mobility reveals that transportmore » on single polymer chains is characterized by the ability of the charge to navigate around kinks and loops in the chain. Lastly, these insights emphasize the connection between the polymer conformations and the transport and thereby offer a route to designing improved device morphologies through molecular design and materials processing.« less

Recent Advances in Wide-Bandgap Photovoltaic Polymers.

PubMed

Cai, Yunhao; Huo, Lijun; Sun, Yanming

2017-06-01

The past decade has witnessed significant advances in the field of organic solar cells (OSCs). Ongoing improvements in the power conversion efficiency of OSCs have been achieved, which were mainly attributed to the design and synthesis of novel conjugated polymers with different architectures and functional moieties. Among various conjugated polymers, the development of wide-bandgap (WBG) polymers has received less attention than that of low-bandgap and medium-bandgap polymers. Here, we briefly summarize recent advances in WBG polymers and their applications in organic photovoltaic (PV) devices, such as tandem, ternary, and non-fullerene solar cells. Addtionally, we also dissuss the application of high open-circuit voltage tandem solar cells in PV-driven electrochemical water dissociation. We mainly focus on the molecular design strategies, the structure-property correlations, and the photovoltaic performance of these WBG polymers. Finally, we extract empirical regularities and provide invigorating perspectives on the future development of WBG photovoltaic materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multivalent conjugates of basic fibroblast growth factor enhance in vitro proliferation and migration of endothelial cells.

PubMed

Zbinden, Aline; Browne, Shane; Altiok, Eda I; Svedlund, Felicia L; Jackson, Wesley M; Healy, Kevin E

2018-05-01

Growth factors hold great promise for regenerative therapies. However, their clinical use has been halted by poor efficacy and rapid clearance from tissue, necessitating the delivery of extremely high doses to achieve clinical effectiveness which has raised safety concerns. Thus, strategies to either enhance growth factor activity at low doses or to increase their residence time within target tissues are necessary for clinical success. In this study, we generated multivalent conjugates (MVCs) of basic fibroblast growth factor (bFGF), a key growth factor involved in angiogenesis and wound healing, to hyaluronic acid (HyA) polymer chains. Multivalent bFGF conjugates (mvbFGF) were fabricated with minimal non-specific interaction observed between bFGF and the HyA chain. The hydrodynamic radii of mvbFGF ranged from ∼50 to ∼75 nm for conjugation ratios of bFGF to HyA chains at low (10 : 1) and high (30 : 1) feed ratios, respectively. The mvbFGF demonstrated enhanced bioactivity compared to unconjugated bFGF in assays of cell proliferation and migration, processes critical to angiogenesis and tissue regeneration. The 30 : 1 mvbFGF outperformed the 10 : 1 conjugate, which could be due to either FGF receptor clustering or interference with receptor mediated internalization and signal deactivation. This study simultaneously investigated the role of both protein to polymer ratio and multivalent conjugate size on their bioactivity, and determined that increasing the protein-to-polymer ratio and conjugate size resulted in greater cell bioactivity.

Tuning the electronic and optical properties of NDT-based conjugated polymers by adopting fused heterocycles as acceptor units: a theoretical study.

PubMed

Cheng, Na; Zhang, Changqiao; Liu, Yongjun

2017-08-01

Donor-acceptor conjugated polymers have been successfully applied in bulk heterojunction solar cell devices. Tuning their donor and acceptor units allows the design of new polymers with desired electronic and optical properties. Here, to screen new candidate polymers based on a newly synthesized donor unit, dithieo[2,3-d:2',3'-d']naphtho[1,2-b:3,4-b']dithiophene (NDT), a series of model polymers with different acceptor units were designed and denoted NDT-A 0 to NDT-A 12 , and the structures and optical properties of those polymers were investigated using DFT and TDDFT calculations. The results of the calculations revealed that the electronic and optical properties of these polymers depend on the acceptor unit present; specifically, their HOMO energies ranged from -4.89 to -5.38 eV, their HOMO-LUMO gaps ranged from 1.30 to 2.80 eV, and their wavelengths of maximum absorption ranged from 538 to 1212 nm. The absorption spectra of NDT-A 1 to NDT-A 6 , NDT-A 8 , NDT-A 9 , and NDT-A 12 occur within the visible region (<900 nm), indicating that these polymers are potential candidates for use in solar cells. On the other hand, the absorption spectra of NDT-A 7 , NDT-A 10 , and NDT-A 11 extend much further into the near-infrared region, implying that they absorb near-infrared light. These polymers could meet the requirements of donor units for use in tandem and ternary solar cells. Graphical abstract Theoretical calculations by TD-DFT reveal that the optical properties of NDT-based conjugated polymers can be well tuned by adopting different acceptor units, and these ploymers are potential donor materials for tandem and ternary solar cells.

Diketopyrrolopyrrole-Based Conjugated Polymer Entailing Triethylene Glycols as Side Chains with High Thin-Film Charge Mobility without Post-Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Si-Fen; Liu, Zi-Tong; Cai, Zheng-Xu

Side chain engineering of conjugated donor-acceptor polymers is a new way to manipulate their optoelectronic properties. Two new diketopyrrolopyrrole (DPP)-terthiophene-based conjugated polymers PDPP3T-1 and PDPP3T-2, with both hydrophilic triethylene glycol (TEG) and hydrophobic alkyl chains, are reported. It is demonstrated that the incorporation of TEG chains has a significant effect on the interchain packing and thin-film morphology with noticeable effect on charge transport. Polymer chains of PDPP3T-1 in which TEG chains are uniformly distributed can self-assemble spontaneously into a more ordered thin film. As a result, the thin film of PDPP3T-1 exhibits high saturated hole mobility up to 2.6 cm(2)more » V-1 s(-1) without any post-treatment. This is superior to those of PDPP3T with just alkyl chains and PDPP3T-2. Moreover, the respective field effect transistors made of PDPP3T-1 can be utilized for sensing ethanol vapor with high sensitivity (down to 100 ppb) and good selectivity.« less

Light and dark-activated biocidal activity of conjugated polyelectrolytes.

PubMed

Ji, Eunkyung; Corbitt, Thomas S; Parthasarathy, Anand; Schanze, Kirk S; Whitten, David G

2011-08-01

This Spotlight on Applications provides an overview of a research program that has focused on the development and mechanistic study of cationic conjugated polyelectrolytes (CPEs) that function as light- and dark-active biocidal agents. Investigation has centered on poly-(phenylene ethynylene) (PPE) type conjugated polymers that are functionalized with cationic quaternary ammonium solubilizing groups. These polymers are found to interact strongly with Gram-positive and Gram-negative bacteria, and upon illumination with near-UV and visible light act to rapidly kill the bacteria. Mechanistic studies suggest that the cationic PPE-type polymers efficiently sensitize singlet oxygen ((1)O(2)), and this cytotoxic agent is responsible for initiating the sequence of events that lead to light-activated bacterial killing. Specific CPEs also exhibit dark-active antimicrobial activity, and this is believed to arise due to interactions between the cationic/lipophilic polymers and the negatively charged outer membrane characteristic of Gram-negative bacteria. Specific results are shown where a cationic CPE with a degree of polymerization of 49 exhibits pronounced light-activated killing of E. coli when present in the cell suspension at a concentration of 1 μg mL(-1).

Solution-based single molecule imaging of surface-immobilized conjugated polymers.

PubMed

Dalgarno, Paul A; Traina, Christopher A; Penedo, J Carlos; Bazan, Guillermo C; Samuel, Ifor D W

2013-05-15

The photophysical behavior of conjugated polymers used in modern optoelectronic devices is strongly influenced by their structural dynamics and conformational heterogeneity, both of which are dependent on solvent properties. Single molecule studies of these polymer systems embedded in a host matrix have proven to be very powerful to investigate the fundamental fluorescent properties. However, such studies lack the possibility of examining the relationship between conformational dynamics and photophysical response in solution, which is the phase from which films for devices are deposited. By developing a synthetic strategy to incorporate a biotin moiety as a surface attachment point at one end of a polyalkylthiophene, we immobilize it, enabling us to make the first single molecule fluorescence measurements of conjugated polymers for long periods of time in solution. We identify fluctuation patterns in the fluorescence signal that can be rationalized in terms of photobleaching and stochastic transitions to reversible dark states. Moreover, by using the advantages of solution-based imaging, we demonstrate that the addition of oxygen scavengers improves optical stability by significantly decreasing the photobleaching rates.

Color tunable hybrid light-emitting diodes based on perovskite quantum dot/conjugated polymer

NASA Astrophysics Data System (ADS)

Germino, José C.; Yassitepe, Emre; Freitas, Jilian N.; Santiago, Glauco M.; Bonato, Luiz Gustavo; de Morais, Andréia; Atvars, Teresa D. Z.; Nogueira, Ana F.

2017-08-01

Inorganic organic metal halide perovskite materials have been investigated for several technological applications, such as photovoltaic cells, lasers, photodetectors and light emitting diodes (LEDs), either in the bulk form or as colloidal nanoparticles. Recently, all inorganic Cesium Lead Halide (CsPbX3, X=Cl,Br, I) perovskite quantum dots (PQDs) were reported with high photoluminescence quantum yield with narrow emission lines in the visible wavelengths. Here, green-emitting perovskite quantum dots (PQDs) prepared by a synthetic method based on a mixture of oleylamine and oleic acid as surfactants were applied in the electroluminescent layer of hybrid LEDs in combination with two different conjugated polymers: polyvinylcarbazole (PVK) or poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO). The performance of the diodes and the emission color tuning upon dispersion of different concentrations of the PQDs in the polymer matrix is discussed. The presented approach aims at the combination of the optical properties of the PQDs and their interaction with wide bandgap conjugated polymers, associated with the solution processing ability of these materials.

Effect of thiolated polymers to textural and mucoadhesive properties of vaginal gel formulations prepared with polycarbophil and chitosan.

PubMed

Cevher, Erdal; Sensoy, Demet; Taha, Mohamed A M; Araman, Ahmet

2008-01-01

The aim of this study was to design and evaluate of mucoadhesive gel formulations for the vaginal application of clomiphene citrate (CLM) for local treatment of human papilloma virus (HPV) infections. Chitosan (CHI) and polycarbophil (PC) were covalently modified using the thioglycolic acid and L-cysteine, respectively. The formation of thiol conjugates of chitosan (CHI-TG) and polycarbophil (PC-CYS) were confirmed by FT-IR analysis and PC-CYS and CHI-TG were found to have 148.42 +/- 4.16 and 41.17 +/- 2.34 micromol of thiol groups per gram of polymer, respectively. One percent CLM gels were prepared by combination of various concentrations of PC and CHI with thiolated conjugates of these polymers. Hardness, compressibility, elasticity, adhesiveness and cohesiveness of the gels were measured by Texture profile analysis and the vaginal mucoadhesion was investigated by mucoadhesion test. The increasing in the amount of the thiol conjugates was found to enhance the elasticity, cohesiveness, adhesiveness and mucoadhesion of the gel formulations but not their hardness and compressibility when compared to gels prepared using their respective parent formulations. Slower release rate of CLM from gels was achieved when the polymer concentrations were increased in the gel formulations. PC and its thiol conjugate were found to prolong the release of CLM longer than 70 h unlike gel formulations prepared using CHI and its thiol conjugate which were able to release CLM up to 12 h. Stability of CLM was preserved during the 3 month stability analysis under controlled room temperature and accelerated conditions.

Modeling charge transport in organic photovoltaic materials.

PubMed

Nelson, Jenny; Kwiatkowski, Joe J; Kirkpatrick, James; Frost, Jarvist M

2009-11-17

The performance of an organic photovoltaic cell depends critically on the mobility of charge carriers within the constituent molecular semiconductor materials. However, a complex combination of phenomena that span a range of length and time scales control charge transport in disordered organic semiconductors. As a result, it is difficult to rationalize charge transport properties in terms of material parameters. Until now, efforts to improve charge mobilities in molecular semiconductors have proceeded largely by trial and error rather than through systematic design. However, recent developments have enabled the first predictive simulation studies of charge transport in disordered organic semiconductors. This Account describes a set of computational methods, specifically molecular modeling methods, to simulate molecular packing, quantum chemical calculations of charge transfer rates, and Monte Carlo simulations of charge transport. Using case studies, we show how this combination of methods can reproduce experimental mobilities with few or no fitting parameters. Although currently applied to material systems of high symmetry or well-defined structure, further developments of this approach could address more complex systems such anisotropic or multicomponent solids and conjugated polymers. Even with an approximate treatment of packing disorder, these computational methods simulate experimental mobilities within an order of magnitude at high electric fields. We can both reproduce the relative values of electron and hole mobility in a conjugated small molecule and rationalize those values based on the symmetry of frontier orbitals. Using fully atomistic molecular dynamics simulations of molecular packing, we can quantitatively replicate vertical charge transport along stacks of discotic liquid crystals which vary only in the structure of their side chains. We can reproduce the trends in mobility with molecular weight for self-organizing polymers using a cheap, coarse-grained structural simulation method. Finally, we quantitatively reproduce the field-effect mobility in disordered C60 films. On the basis of these results, we conclude that all of the necessary building blocks are in place for the predictive simulation of charge transport in macromolecular electronic materials and that such methods can be used as a tool toward the future rational design of functional organic electronic materials.

Electrografting of conductive oligomers and polymers using diazonium electroreduction

NASA Astrophysics Data System (ADS)

Lacroix, Jean Christophe; Trippe-Allard, Gaelle; Ghilane, Jalal; Martin, Pascal

2014-03-01

This paper describes the attachment of conjugated oligomers onto electrode surface through the reduction of diazonium compounds. In this connection some properties of conjugated oligomers and of layers grafted through diazonium electroreduction will first be briefly presented. The electrochemical behavior of conjugated oligomers grafted on a surface using diazonium electroreduction will then be discussed.

Poly(2-ethyl-2-oxazoline) conjugates with doxorubicin for cancer therapy: In vitro and in vivo evaluation and direct comparison to poly[N-(2-hydroxypropyl)methacrylamide] analogues.

PubMed

Sedlacek, Ondrej; Monnery, Bryn D; Mattova, Jana; Kucka, Jan; Panek, Jiri; Janouskova, Olga; Hocherl, Anita; Verbraeken, Bart; Vergaelen, Maarten; Zadinova, Marie; Hoogenboom, Richard; Hruby, Martin

2017-11-01

We designed and synthesized a new delivery system for the anticancer drug doxorubicin based on a biocompatible hydrophilic poly(2-ethyl-2-oxazoline) (PEtOx) carrier with linear architecture and narrow molar mass distribution. The drug is connected to the polymer backbone via an acid-sensitive hydrazone linker, which allows its triggered release in the tumor. The in vitro studies demonstrate successful cellular uptake of conjugates followed by release of the cytostatic cargo. In vivo experiments in EL4 lymphoma bearing mice revealed prolonged blood circulation, increased tumor accumulation and enhanced antitumor efficacy of the PEtOx conjugate having higher molecular weight (40 kDa) compared to the lower molecular weight (20 kDa) polymer. Finally, the in vitro and in vivo anti-cancer properties of the prepared PEtOx conjugates were critically compared with those of the analogous system based on the well-established PHPMA carrier. Despite the relatively slower intracellular uptake of PEtOx conjugates, resulting also in their lower cytotoxicity, there are no substantial differences in in vivo biodistribution and anti-cancer efficacy of both classes of polymer-Dox conjugates. Considering the synthetic advantages of poly(2-alkyl-2-oxazoline)s, the presented study demonstrates their potential as a versatile alternative to well-known PEO- or PHPMA-based materials for construction of drug delivery systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Online size-exclusion high-performance liquid chromatography light scattering and differential refractometry methods to determine degree of polymer conjugation to proteins and protein-protein or protein-ligand association states.

PubMed

Kendrick, B S; Kerwin, B A; Chang, B S; Philo, J S

2001-12-15

Characterizing the solution structure of protein-polymer conjugates and protein-ligand interactions is important in fields such as biotechnology and biochemistry. Size-exclusion high-performance liquid chromatography with online classical light scattering (LS), refractive index (RI), and UV detection offers a powerful tool in such characterization. Novel methods are presented utilizing LS, RI, and UV signals to rapidly determine the degree of conjugation and the molecular mass of the protein conjugate. Baseline resolution of the chromatographic peaks is not required; peaks need only be sufficiently separated to represent relatively pure fractions. An improved technique for determining the polypeptide-only mass of protein conjugates is also described. These techniques are applied to determining the degree of erythropoietin glycosylation, the degree of polyethylene glycol conjugation to RNase A and brain-derived neurotrophic factor, and the solution association states of these molecules. Calibration methods for the RI, UV, and LS detectors will also be addressed, as well as online methods to determine protein extinction coefficients and dn/dc values both unconjugated and conjugated protein molecules. (c)2001 Elsevier Science.

Design of polymer conjugated 3-helix micelles as nanocarriers with tunable shapes.

PubMed

Ma, Dan; DeBenedictis, Elizabeth P; Lund, Reidar; Keten, Sinan

2016-11-24

Amphiphilic peptide-polymer conjugates have the ability to form stable nanoscale micelles, which show great promise for drug delivery and other applications. A recent design has utilized the end-conjugation of alkyl chains to 3-helix coiled coils to achieve amphiphilicity, combined with the side-chain conjugation of polyethylene glycol (PEG) to tune micelle size through entropic confinement forces. Here we investigate this phenomenon in depth, using coarse-grained dissipative particle dynamics (DPD) simulations in an explicit solvent and micelle theory. We analyze the conformations of PEG chains conjugated to three different positions on 3-helix bundle peptides to ascertain the degree of confinement upon assembly, as well as the ordering of the subunits making up the micelle. We discover that the micelle size and stability is dictated by a competition between the entropy of PEG chain conformations in the assembled state, as well as intermolecular cross-interactions among PEG chains that promote cohesion between neighboring conjugates. Our analyses build on the role of PEG molecular weight and conjugation site and lead to computational phase diagrams that can be used to design 3-helix micelles. This work opens pathways for the design of multifunctional micelles with tunable size, shape and stability.

Separation efficiency of free-solution conjugated electrophoresis with drag-tags incorporating a synthetic amino acid.

PubMed

Seo, Kyung-Ho; Chu, Hun-Su; Yoo, Tae Hyeon; Lee, Sun-Gu; Won, Jong-In

2016-03-01

DNA sequencing or separation by conventional capillary electrophoresis with a polymer matrix has some inherent drawbacks, such as the expense of polymer matrix and limitations in sequencing read length. As DNA fragments have a linear charge-to-friction ratio in free solution, DNA fragments cannot be separated by size. However, size-based separation of DNA is possible in free-solution conjugate electrophoresis (FSCE) if a "drag-tag" is attached to DNA fragments because the tag breaks the linear charge-to-friction scaling. Although several previous studies have demonstrated the feasibility of DNA separation by free-solution conjugated electrophoresis, generation of a monodisperse drag-tag and identification of a strong, site-specific conjugation method between a DNA fragment and a drag-tag are challenges that still remain. In this study, we demonstrate an efficient FSCE method by conjugating a biologically synthesized elastin-like polypeptide (ELP) and green fluorescent protein (GFP) to DNA fragments. In addition, to produce strong and site-specific conjugation, a methionine residue in drag-tags is replaced with homopropargylglycine (Hpg), which can be conjugated specifically to a DNA fragment with an azide site. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrical memory characteristics of a nondoped pi-conjugated polymer bearing carbazole moieties.

PubMed

Park, Samdae; Lee, Taek Joon; Kim, Dong Min; Kim, Jin Chul; Kim, Kyungtae; Kwon, Wonsang; Ko, Yong-Gi; Choi, Heungyeal; Chang, Taihyun; Ree, Moonhor

2010-08-19

Poly[bis(9H-carbazole-9-ethyl)dipropargylmalonate] (PCzDPM) is a novel pi-conjugated polymer bearing carbazole moieties that has been synthesized by polymerization of bis(9H-carbazole-9-ethyl)dipropargylmalonate with the aid of molybdenum chloride solution as the catalyst. This polymer is thermally stable up to 255 degrees C under a nitrogen atmosphere and 230 degrees C in air ambient; its glass-transition temperature is 147 or 128 degrees C, depending on the polymer chain conformation (helical or planar structure). The charge-transport characteristics of PCzDPM in nanometer-scaled thin films were studied as a function of temperature and film thickness. PCzDPM films with a thickness of 15-30 nm were found to exhibit very stable dynamic random access memory (DRAM) characteristics without polarity. Furthermore, the polymer films retain DRAM characteristics up to 180 degrees C. The ON-state current is dominated by Ohmic conduction, and the OFF-state current appears to undergo a transition from Ohmic to space-charge-limited conduction with a shallow-trap distribution. The ON/OFF switching of the devices is mainly governed by filament formation. The filament formation mechanism for the switching process is supported by the metallic properties of the PCzDPM film, which result in the temperature dependence of the ON-state current. In addition, the structure of this pi-conjugated polymer was found to vary with its thermal history; this change in structure can affect filament formation in the polymer film.

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications.

PubMed

Yamamoto, Yohei; Okada, Daichi; Kushida, Soh; Ngara, Zakarias Seba; Oki, Osamu

2017-06-02

This paper describes three methods of preparing fluorescent microspheres comprising π-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, π-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (µ-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, µ-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Catechol polymers for pH-responsive, targeted drug delivery to cancer cells.

PubMed

Su, Jing; Chen, Feng; Cryns, Vincent L; Messersmith, Phillip B

2011-08-10

A novel cell-targeting, pH-sensitive polymeric carrier was employed in this study for delivery of the anticancer drug bortezomib (BTZ) to cancer cells. Our strategy is based on facile conjugation of BTZ to catechol-containing polymeric carriers that are designed to be taken up selectively by cancer cells through cell surface receptor-mediated mechanisms. The polymer used as a building block in this study was poly(ethylene glycol), which was chosen for its ability to reduce nonspecific interactions with proteins and cells. The catechol moiety was exploited for its ability to bind and release borate-containing therapeutics such as BTZ in a pH-dependent manner. In acidic environments, such as in cancer tissue or the subcellular endosome, BTZ dissociates from the polymer-bound catechol groups to liberate the free drug, which inhibits proteasome function. A cancer-cell-targeting ligand, biotin, was presented on the polymer carriers to facilitate targeted entry of drug-loaded polymer carriers into cancer cells. Our study demonstrated that the cancer-targeting drug-polymer conjugates dramatically enhanced cellular uptake, proteasome inhibition, and cytotoxicity toward breast carcinoma cells in comparison with nontargeting drug-polymer conjugates. The pH-sensitive catechol-boronate binding mechanism provides a chemoselective approach for controlling the release of BTZ in targeted cancer cells, establishing a concept that may be applied in the future toward other boronic acid-containing therapeutics to treat a broad range of diseases. © 2011 American Chemical Society

Using inositol as a biocompatible ligand for efficient transgene expression

PubMed Central

Zhang, Lei; Bellis, Susan L; Fan, Yiwen; Wu, Yunkun

2015-01-01

Transgene transfection techniques using cationic polymers such as polyethylenimines (PEIs) and PEI derivatives as gene vectors have shown efficacy, although they also have shortcomings. PEIs have decent DNA-binding capability and good cell internalization performance, but they cannot deliver gene payloads very efficiently to cell nuclei. In this study, three hyperbranched polyglycerol-polyethylenimine (PG6-PEI) polymers conjugated with myo-inositol (INO) molecules were developed. The three resulting PG6-PEI-INO polymers have an increased number of INO ligands per molecule. PG6-PEI-INO 1 had only 14 carboxymethyl INO (CMINO) units per molecule. PG6-PEI-INO 2 had approximately 130 CMINO units per molecule. PG6-PEI-INO 3 had as high as 415 CMINO units approximately. Mixing PG6-PEI-INO polymers with DNA produced compact nanocomposites. We then performed localization studies using fluorescent microscopy. As the number of conjugated inositol ligands increased in PG6-PEI-INO polymers, there was a corresponding increase in accumulation of the polymers within 293T cell nuclei. Transfection performed with spherical 293T cells yielded 82% of EGFP-positive cells when using PG6-PEI-INO 3 as the vehicle. Studies further revealed that extracellular adenosine triphosphate (eATP) can inhibit the transgene efficiency of PG6-PEI-INO polymers, as compared with PEI and PG6-PEI that were not conjugated with inositol. Our work unveiled the possibility of using inositol as an effective ligand for transgene expression. PMID:25926732

Effectiveness of External Electric Field Treatment of Conjugated Polymers in Bulk-Heterojunction Solar Cells.

PubMed

Solanki, Ankur; Bagui, Anirban; Long, Guankui; Wu, Bo; Salim, Teddy; Chen, Yongsheng; Lam, Yeng Ming; Sum, Tze Chien

2016-11-30

External electric field treatment (EFT) on P3HT:PCBM bulk heterojunction (BHJ) devices was recently found to be a viable approach for improving the power conversion efficiencies (PCEs) through modulating the blend nanomorphology. However, its effectiveness over the broad family of polymer-fullerene blends remains unclear. Herein, we investigate the effects of external EFT on various polymer-fullerene blends with distinct morphologies stemming from the difference in molecular structure of the polymers (i.e., semicrystalline vs amorphous) in a bid to establish a clear morphology-function-charge dynamics relationship to the photovoltaic performance. Our findings reveal that EFT promotes self-organization of the semicrystalline thiophene-based conjugated polymers (i.e., P3HT and P3BT) while it was ineffective for the amorphous polymers (i.e., PTB7 and PCPDTBT) even at the maximum applied E-field of 8 kV cm -1 . Transient absorption spectroscopy shows an improvement in the initial charge-carrier and polaron formation from delocalized excitons in the E-field treated semicrystalline blends compared to their untreated reference samples. Interfacial trap-assisted monomolecular and trap-free bimolecular recombination at nanosecond-microsecond time scale in the E-field treated P3BT:PC60BM devices are significantly suppressed. Importantly, our findings shed new light and provide guidelines on the effectiveness of utilizing external EFT to enhance the PCEs of a larger family of conjugated polymer-based BHJ OSCs.

Electrospun aniline-tetramer-co-polycaprolactone fibres for conductive, biodegradable scaffolds.

PubMed

Guex, A G; Spicer, C D; Armgarth, A; Gelmi, A; Humphrey, E J; Terracciano, C M; Harding, S; Stevens, M M

2017-09-01

Conjugated polymers have been proposed as promising materials for scaffolds in tissue engineering applications. The restricted processability and biodegradability of conjugated polymers limit their use for biomedical applications however. Here we synthesised a block- co -polymer of aniline tetramer and PCL (AT-PCL), and processed it into fibrous non-woven scaffolds by electrospinning. We showed that fibronectin (Fn) adhesion was dependant on the AT-PCL oxidative state, with a reduced Fn unfolding length on doped membranes. Furthermore, we demonstrated the cytocompatibility and potential of these membranes to support the growth and osteogenic differentiation of MC3T3-E1 over 21 days.

Exciton intrachain transport induced by interchain packing configurations in conjugated polymers.

PubMed

Meng, Ruixuan; Gao, Kun; Zhang, Gaiyan; Han, Shixuan; Yang, Fujiang; Li, Yuan; Xie, Shijie

2015-07-28

Based on a tight binding model combined with a nonadiabatic dynamics approach, we theoretically investigate the exciton intrachain transport in conjugated polymers with different interchain packing configurations. We construct two different interchain packing configurations, i.e. linear and exponential forms, and simulate the dynamical processes of the exciton transport in these systems. We find that, in both cases, there exists a distribution of driving force for exciton transport, which stems from the gradient of the exciton creation energy along the chains. This finding enriches the picture of exciton transport in polymers and provides a new idea to improve the exciton transport length in polymeric photovoltaic devices.

Emulsion-Based RIR-MAPLE Deposition of Conjugated Polymers: Primary Solvent Effect and Its Implications on Organic Solar Cell Performance.

PubMed

Ge, Wangyao; Li, Nan K; McCormick, Ryan D; Lichtenberg, Eli; Yingling, Yaroslava G; Stiff-Roberts, Adrienne D

2016-08-03

Emulsion-based, resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) has been demonstrated as an alternative technique to deposit conjugated polymer films for photovoltaic applications; yet, a fundamental understanding of how the emulsion target characteristics translate into film properties and solar cell performance is unclear. Such understanding is crucial to enable the rational improvement of organic solar cell (OSC) efficiency and to realize the expected advantages of emulsion-based RIR-MAPLE for OSC fabrication. In this paper, the effect of the primary solvent used in the emulsion target is studied, both experimentally and theoretically, and it is found to determine the conjugated polymer cluster size in the emulsion as well as surface roughness and internal morphology of resulting polymer films. By using a primary solvent with low solubility-in-water and low vapor pressure, the surface roughness of deposited P3HT and PCPDTBT polymer films was reduced to 10 nm, and the efficiency of P3HT:PC61BM OSCs was increased to 3.2% (∼100 times higher compared to the first MAPLE OSC demonstration [ Caricato , A. P. ; Appl. Phys. Lett. 2012 , 100 , 073306 ]). This work unveils the mechanism of polymer film formation using emulsion-based RIR-MAPLE and provides insight and direction to determine the best ways to take advantage of the emulsion target approach to control film properties for different applications.

Unraveling the Solution-State Supramolecular Structures of Donor-Acceptor Polymers and their Influence on Solid-State Morphology and Charge-Transport Properties.

PubMed

Zheng, Yu-Qing; Yao, Ze-Fan; Lei, Ting; Dou, Jin-Hu; Yang, Chi-Yuan; Zou, Lin; Meng, Xiangyi; Ma, Wei; Wang, Jie-Yu; Pei, Jian

2017-11-01

Polymer self-assembly in solution prior to film fabrication makes solution-state structures critical for their solid-state packing and optoelectronic properties. However, unraveling the solution-state supramolecular structures is challenging, not to mention establishing a clear relationship between the solution-state structure and the charge-transport properties in field-effect transistors. Here, for the first time, it is revealed that the thin-film morphology of a conjugated polymer inherits the features of its solution-state supramolecular structures. A "solution-state supramolecular structure control" strategy is proposed to increase the electron mobility of a benzodifurandione-based oligo(p-phenylene vinylene) (BDOPV)-based polymer. It is shown that the solution-state structures of the BDOPV-based conjugated polymer can be tuned such that it forms a 1D rod-like structure in good solvent and a 2D lamellar structure in poor solvent. By tuning the solution-state structure, films with high crystallinity and good interdomain connectivity are obtained. The electron mobility significantly increases from the original value of 1.8 to 3.2 cm 2 V -1 s -1 . This work demonstrates that "solution-state supramolecular structure" control is critical for understanding and optimization of the thin-film morphology and charge-transport properties of conjugated polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

MACROMOLECULAR THERAPEUTICS

PubMed Central

Yang, Jiyuan; Kopeček, Jindřich

2014-01-01

This review covers water-soluble polymer-drug conjugates and macromolecules that possess biological activity without attached low molecular weight drugs. The main design principles of traditional and backbone degradable polymer-drug conjugates as well as the development of a new paradigm in nanomedicines – (low molecular weight) drug-free macromolecular therapeutics are discussed. To address the biological features of cancer, macromolecular therapeutics directed to stem/progenitor cells and the tumor microenvironment are deliberated. Finally, the future perspectives of the field are briefly debated. PMID:24747162

Synthesis of Metal Phthalocyanine Sheet Polymers

NASA Technical Reports Server (NTRS)

Achar, B. N.; Fohlen, G. M.; Parker, J. A.

1986-01-01

New method for synthesizing metal phthalocyanine tetracarboxylic acids (MPTCA's) yields high purity end product. In addition, high-purity metal phthalocyanine sheet polymers synthesized from compounds. Monomer formed into sheet polymer by heating. Units of polymer linked in manner similar to phenyl-group linkages in biphenyl: Conjugation extends throughout macromolecule, thereby increasing delocalization of TT-electrons. Increases conductivity and thermal stability of polymer.

Conjugated microporous polymers-based fluorescein for fluorescence detection of 2,4,6-trinitrophenol.

PubMed

Geng, Tong-Mou; Ye, Sai-Nan; Wang, Yu; Zhu, Hai; Wang, Xie; Liu, Xue

2017-04-01

2,4,6-Trinitrophenol (TNP, also called picric acid, PA) pose a large threat to environmental health, public safety and military security. Conjugated microporous polymers are emerging new fluorescence sensing materials for TNP. In this paper, we report the synthesis of two fluorescein containing conjugated microporous polymers (DTF and TTF) through the palladium catalyzed Sonogashira-Hagihara polycondensation reactions of tetraiodofluorescein sodium salt (TIFA) with 1,4-diethynylbenzene (DEB) or 1,3,5-triethynylbenzene (TEB). DTF and TTF are porous with the BET surface areas of 705 and 712m 2 g -1 and exhibit high chemical and thermal stabilities. The formation of conjugated polymers with the incorporation of ethynyl groups leads to the fluorescent properties. The fluorescence quenching behaviors of DTF by nitroaromatic analytes in THF suspension are investigated. It is found that the fluorescence of DTF can be effectively quenched by 2,4,6-trinitrophenol over 2-nitrophenol (NP), 4-nitrotoluene (NT), nitrobenzene (NB), phenol (PhOH), p-dichlorobenzene (DClB) and 2,4-dinitrotoluene (DNT) with an SV constant of 2.08×10 3 Lmol -1 and a detection limit of 7.22×10 -7 molL -1 (0.165mgL -1 ). In short, the DTF may be a new kind of fluorescence sensing material for detecting TNP. Copyright © 2016 Elsevier B.V. All rights reserved.

Structure-processing-property correlations in thin films of conjugated polymer nanocomposites and blends

NASA Astrophysics Data System (ADS)

Sreeram, Arvind

Conjugated polymers have found several applications in recent years, in energy conversion and storage devices such as organic light emitting diodes, solar cells, batteries, and super capacitors. Thin films of polymers used for these applications need to be mechanically and thermally stable to withstand the harsh operating conditions. Although there is significant information on the optoelectronic properties of many of these polymers, there are only few studies on their mechanical properties. There is little information in the literature on how processing of these films influence mechanical properties. In the first part of this study, poly(p-phenylene vinylene) (PPV) films were prepared by thermolytic conversion of poly[p -phenylene (tetrahydrothiophenium)ethylene chloride] precursor films, at different temperatures and the kinetics of reaction was investigated using thermogravimetry and Fourier transform infrared (FTIR) spectroscopy. The mechanical properties of the films, studied using nanoindentation, showed a dependence on the extent of conversion and chemical composition of the films. The presence of chemical defects (e.g., carbonyl groups, detected using FTIR spectroscopy), was also found to have a noticeable effect on the modulus and hardness of the films. The storage modulus, E', and plasticity decreased with an increase in conversion, whereas the loss modulus, E", showed the opposite trend. Both the precursor and the fully-converted PPV films were found to have significantly lower E" than E', consistent with the glassy nature of the polymers at room temperature. In the second part of the study, polyacetylene films were synthesized by acid-catalyzed dehydration reaction of poly(vinyl alcohol) (PVA) precursor films. The kinetics of this reaction was monitored by thermogravimetry. The chemical structure of the conjugated polymer films was characterized by Raman and IR spectroscopy. Polyacetylene films incorporated with 1-propyl-3-methylimidazolium ionic liquid (IL) could be obtained in a single step reaction. The incorporation of IL in the film, not only greatly improved its mechanical properties, by acting as a plasticizer, but also imparted a dual mechanism of charge transport. The segments of conjugated double bonds imparted electronic conductivity to the films, and the IL resulted in ionic conductivity. The presence of both electronic and ionic conduction pathways in the films was confirmed by electrochemical impedance spectroscopy (EIS). These IL-imbibed conjugated polymer films are promising as materials for electrochemical energy conversion and storage. In the third part of this work, conjugated polymer films containing multiwalled carbon nanotubes (MWNT) and graphene nanoplatelets (GNP) were synthesized and characterized. PPV--MWNT nanocomposite films and PA--GNP nanocomposite films were characterized using a variety of analytical techniques including transmission electron microscopy, quasistatic and dynamic nanoindentaiton, electrochemical impedance spectroscopy, and cyclic voltammetry. Potential application of these films is in electrochemical supercapacitors.

Development and validation of an in vitro pharmacokinetic/pharmacodynamic model to test the antibacterial efficacy of antibiotic polymer conjugates.

PubMed

Azzopardi, Ernest A; Ferguson, Elaine L; Thomas, David W

2015-04-01

This study describes the use of a novel, two-compartment, static dialysis bag model to study the release, diffusion, and antibacterial activity of a novel, bioresponsive dextrin-colistin polymer conjugate against multidrug resistant (MDR) wild-type Acinetobacter baumannii. In this model, colistin sulfate, at its MIC, produced a rapid and extensive drop in viable bacterial counts (<2 log10 CFU/ml at 4 h); however, a marked recovery was observed thereafter, with regrowth equivalent to that of control by 48 h. In contrast, dextrin-colistin conjugate, at its MIC, suppressed bacterial growth for up to 48 h, with 3 log10 CFU/ml lower bacterial counts after 48 h than those of controls. Doubling the concentration of dextrin-colistin conjugate (to 2× MIC) led to an initial bacterial killing of 3 log10 CFU/ml at 8 h, with a similar regrowth profile to 1× MIC treatment thereafter. The addition of colistin sulfate (1× MIC) to dextrin-colistin conjugate (1× MIC) resulted in undetectable bacterial counts after 4 h, followed by suppressed bacterial growth (3.5 log10 CFU/ml lower than that of control at 48 h). Incubation of dextrin-colistin conjugates with infected wound exudate from a series of burn patients (n = 6) revealed an increasing concentration of unmasked colistin in the outer compartment (OC) over time (up to 86.3% of the initial dose at 48 h), confirming that colistin would be liberated from the conjugate by endogenous α-amylase within the wound environment. These studies confirm the utility of this model system to simulate the pharmacokinetics of colistin formation in humans administered dextrin-colistin conjugates and further supports the development of antibiotic polymer conjugates in the treatment of MDR infections. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Amplified spontaneous emission from the exciplex state of a conjugated polymer "PFO" in oleic acid

NASA Astrophysics Data System (ADS)

Idriss, Hajo; Taha, Kamal K.; Aldaghri, O.; Alhathlool, R.; AlSalhi, M. S.; Ibnaouf, K. H.

2016-09-01

The amplified spontaneous emission (ASE) characteristics of a conjugated polymer poly (9, 9-dioctylfluorenyl-2, 7-diyl) (PFO) in oleic acid have been studied under different concentrations and temperatures. Here, the ASE spectra of PFO in oleic acid have been obtained using a transverse cavity configuration where the conjugated PFO was pumped by laser pulses from the third harmonic of Nd: YAG laser (355 nm). The PFO in oleic acid produces ASE from an exciplex state - a new molecular species. The obtained results were compared with the PFO in benzene. Such ASE spectra from the exciplex state have not been observed for the PFO in benzene.

Selective fluorescent detection of aspartic acid and glutamic acid employing dansyl hydrazine dextran conjugate.

PubMed

Nasomphan, Weerachai; Tangboriboonrat, Pramuan; Tanapongpipat, Sutipa; Smanmoo, Srung

2014-01-01

Highly water soluble polymer (DD) was prepared and evaluated for its fluorescence response towards various amino acids. The polymer consists of dansyl hydrazine unit conjugated into dextran template. The conjugation enhances higher water solubility of dansyl hydrazine moiety. Of screened amino acids, DD exhibited selective fluorescence quenching in the presence of aspartic acid (Asp) and glutamic acid (Glu). A plot of fluorescence intensity change of DD against the concentration of corresponding amino acids gave a good linear relationship in the range of 1 × 10(-4) M to 25 × 10(-3) M. This establishes DD as a potential polymeric sensor for selective sensing of Asp and Glu.

Backbone degradable multiblock N-(2-hydroxypropyl)methacrylamide copolymer conjugates via reversible addition-fragmentation chain transfer polymerization and thiol-ene coupling reaction.

PubMed

Pan, Huaizhong; Yang, Jiyuan; Kopecková, Pavla; Kopecek, Jindrich

2011-01-10

Telechelic water-soluble HPMA copolymers and HPMA copolymer-doxorubicin (DOX) conjugates have been synthesized by RAFT polymerization mediated by a new bifunctional chain transfer agent (CTA) that contains an enzymatically degradable oligopeptide sequence. Postpolymerization aminolysis followed by chain extension with a bis-maleimide resulted in linear high molecular weight multiblock HPMA copolymer conjugates. These polymers are enzymatically degradable; in addition to releasing the drug (DOX), the degradation of the polymer backbone resulted in products with molecular weights similar to the starting material and below the renal threshold. The new multiblock HPMA copolymers hold potential as new carriers of anticancer drugs.

Planar conjugated polymers containing 9,10-disubstituted phenanthrene units for efficient polymer solar cells.

PubMed

Li, Guangwu; Kang, Chong; Li, Cuihong; Lu, Zhen; Zhang, Jicheng; Gong, Xue; Zhao, Guangyao; Dong, Huanli; Hu, Wenping; Bo, Zhishan

2014-06-01

Four novel conjugated polymers (P1-4) with 9,10-disubstituted phenanthrene (PhA) as the donor unit and 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit are synthesized and characterized. These polymers are of medium bandgaps (2.0 eV), low-lying HOMO energy levels (below -5.3 eV), and high hole mobilities (in the range of 3.6 × 10(-3) to 0.02 cm(2) V(-1) s(-1) ). Bulk heterojunction (BHJ) polymer solar cells (PSCs) with P1-4:PC71 BM blends as the active layer and an alcohol-soluble fullerene derivative (FN-C60) as the interfacial layer between the active layer and cathode give the best power conversion efficiency (PCE) of 4.24%, indicating that 9,10-disubstituted PhA are potential donor materials for high-efficiency BHJ PSCs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lithium salt doped conjugated polymers as electron transporting materials for highly efficient blue polymer light-emitting diodes

NASA Astrophysics Data System (ADS)

Huang, Fei; Shih, Ping-I.; Liu, Michelle S.; Shu, Ching-Fong; Jen, Alex K.-Y.

2008-12-01

Highly efficient blue polymer light-emitting diodes (PLEDs) are fabricated using a conjugated polymer, poly[9,9-bis(2-(2-(2-diethanol-amino-ethoxy) ethoxy) ethyl) fluorene-alt-4, 4'-phenylether] as an electron transporting layer (ETL). It was found that the performance of these blue-emitting devices could be greatly improved if the ETL was doped with LiF or Li2CO3 salts. A bis[(4,6-di-fluorophenyl)-pyridinato-N, C2] (picolinate) Ir(III) (FIrpic) complex based blue phosphorescent PLED exhibited a maximum luminance efficiency of 20.3 cd/A with a luminance of 1600 cd/m2 at the current density of 7.9 mA/cm2 and drive voltage of 8.0 V.

Influence of molecular designs on polaronic and vibrational transitions in a conjugated push-pull copolymer

NASA Astrophysics Data System (ADS)

Cobet, Christoph; Gasiorowski, Jacek; Menon, Reghu; Hingerl, Kurt; Schlager, Stefanie; White, Matthew S.; Neugebauer, Helmut; Sariciftci, N. Serdar; Stadler, Philipp

2016-10-01

Electron-phonon interactions of free charge-carriers in doped pi-conjugated polymers are conceptually described by 1-dimensional (1D) delocalization. Thereby, polaronic transitions fit the 1D-Froehlich model in quasi-confined chains. However, recent developments in conjugated polymers have diversified the backbones to become elaborate heterocylcic macromolecules. Their complexity makes it difficult to investigate the electron-phonon coupling. In this work we resolve the electron-phonon interactions in the ground and doped state in a complex push-pull polymer. We focus on the polaronic transitions using in-situ spectroscopy to work out the differences between single-unit and push-pull systems to obtain the desired structural- electronic correlations in the doped state. We apply the classic 1D-Froehlich model to generate optical model fits. Interestingly, we find the 1D-approach in push-pull polarons in agreement to the model, pointing at the strong 1D-character and plain electronic structure of the push-pull structure. In contrast, polarons in the single-unit polymer emerge to a multi- dimensional problem difficult to resolve due to their anisotropy. Thus, we report an enhancement of the 1D-character by the push-pull concept in the doped state - an important view in light of the main purpose of push-pull polymers for photovoltaic devices.

High-Performance Organic Photodetectors from a High-Bandgap Indacenodithiophene-Based π-Conjugated Donor-Acceptor Polymer.

PubMed

Benavides, Cindy Montenegro; Murto, Petri; Chochos, Christos L; Gregoriou, Vasilis G; Avgeropoulos, Apostolos; Xu, Xiaofeng; Bini, Kim; Sharma, Anirudh; Andersson, Mats R; Schmidt, Oliver; Brabec, Christoph J; Wang, Ergang; Tedde, Sandro F

2018-04-18

A conjugated donor-acceptor polymer, poly[4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro- s-indaceno[1,2- b:5,6- b']dithiophene-2,7-diyl- alt-5-(2-ethylhexyl)-4 H-thieno[3,4- c]pyrrole-4,6(5 H)-dione-1,3-diyl] (PIDT-TPD), is blended with the fullerene derivative [6,6]phenyl-C61-butyric acid methyl ester (PC 61 BM) for the fabrication of thin and solution-processed organic photodetectors (OPDs). Systematic screening of the concentration ratio of the blend and the molecular weight of the polymer is performed to optimize the active layer morphology and the OPD performance. The device comprising a medium molecular weight polymer (27.0 kg/mol) in a PIDT-TPD:PC 61 BM 1:1 ratio exhibits an external quantum efficiency of 52% at 610 nm, a dark current density of 1 nA/cm 2 , a detectivity of 1.44 × 10 13 Jones, and a maximum 3 dB cutoff frequency of 100 kHz at -5 V bias. These results are remarkable among the state-of-the-art red photodetectors based on conjugated polymers. As such, this work presents a functional organic active material for high-speed OPDs with a linear photoresponse at different light intensities.

Controlled conjugated backbone twisting for an increased open-circuit voltage while having a high short-circuit current in poly(hexylthiophene) derivatives.

PubMed

Ko, Sangwon; Hoke, Eric T; Pandey, Laxman; Hong, Sanghyun; Mondal, Rajib; Risko, Chad; Yi, Yuanping; Noriega, Rodrigo; McGehee, Michael D; Brédas, Jean-Luc; Salleo, Alberto; Bao, Zhenan

2012-03-21

Conjugated polymers with nearly planar backbones have been the most commonly investigated materials for organic-based electronic devices. More twisted polymer backbones have been shown to achieve larger open-circuit voltages in solar cells, though with decreased short-circuit current densities. We systematically impose twists within a family of poly(hexylthiophene)s and examine their influence on the performance of polymer:fullerene bulk heterojunction (BHJ) solar cells. A simple chemical modification concerning the number and placement of alkyl side chains along the conjugated backbone is used to control the degree of backbone twisting. Density functional theory calculations were carried out on a series of oligothiophene structures to provide insights on how the sterically induced twisting influences the geometric, electronic, and optical properties. Grazing incidence X-ray scattering measurements were performed to investigate how the thin-film packing structure was affected. The open-circuit voltage and charge-transfer state energy of the polymer:fullerene BHJ solar cells increased substantially with the degree of twist induced within the conjugated backbone--due to an increase in the polymer ionization potential--while the short-circuit current decreased as a result of a larger optical gap and lower hole mobility. A controlled, moderate degree of twist along the poly(3,4-dihexyl-2,2':5',2''-terthiophene) (PDHTT) conjugated backbone led to a 19% enhancement in the open-circuit voltage (0.735 V) vs poly(3-hexylthiophene)-based devices, while similar short-circuit current densities, fill factors, and hole-carrier mobilities were maintained. These factors resulted in a power conversion efficiency of 4.2% for a PDHTT:[6,6]-phenyl-C(71)-butyric acid methyl ester (PC(71)BM) blend solar cell without thermal annealing. This simple approach reveals a molecular design avenue to increase open-circuit voltage while retaining the short-circuit current.

Effectively delivering a unique hsp90 inhibitor using star polymers.

PubMed

Kim, Seong Jong; Ramsey, Deborah M; Boyer, Cyrille; Davis, Thomas P; McAlpine, Shelli R

2013-07-25

We report the synthesis of a novel heat shock protein 90 (hsp90) inhibitor conjugated to a star polymer. Using reversible addition-fragmentation chain-transfer (RAFT) polymerization, we prepared star polymers comprised of PEG attached to a predesigned functional core. The stars were cross-linked using disulfide linkers, and a tagged version of our hsp90 inhibitor was conjugated to the polymer core to generate nanoparticles (14 nM). Dynamic light scattering showed that the nanoparticles were stable in cell growth media for 5 days, and HPLC analysis of compound-release at 3 different pH values showed that release was pH dependent. Cell cytotoxicity studies and confocal microscopy verify that our hsp90 inhibitor was delivered to cells using this nanoparticle delivery system. Further, delivery of our hsp90 inhibitor using star polymer induces apoptosis by a caspase 3-dependent pathway. These studies show that we can deliver our hsp90 inhibitor effectively using star polymers, and induce apoptosis by the same pathway as the parent compound.

Designing interchain and intrachain properties of conjugated polymers for latent optical information encoding

DOE PAGES

Chung, Kyeongwoon; McAllister, Andrew; Bilby, David; ...

2015-09-03

Building molecular-design insights for controlling both the intrachain and the interchain properties of conjugated polymers (CPs) is essential to determine their characteristics and to optimize their performance in applications. However, most CP designs have focused on the conjugated main chain to control the intrachain properties, while the design of side chains is usually used to render CPs soluble, even though the side chains critically affect the interchain packing. Here, we present a straightforward and effective design strategy for modifying the optical and electrochemical properties of diketopyrrolopyrrole-based CPs by controlling both the intrachain and interchain properties in a single system. Themore » synthesized polymers, P1, P2 and P3, show almost identical optical absorption spectra in solution, manifesting essentially the same intrachain properties of the three CPs having restricted effective conjugation along the main chain. However, the absorption spectra of CP films are gradually tuned by controlling the interchain packing through the side-chain design. Here, based on the tailored optical properties, we demonstrate the encoding of latent optical information utilizing the CPs as security inks on a silica substrate, which reveals and conceals hidden information upon the reversible aggregation/deaggregation of CPs.« less

Nanoarmored Enzymes for Organic Enzymology: Synthesis and Characterization of Poly(2-Alkyloxazoline)-Enzyme Conjugates.

PubMed

Leurs, Melanie; Tiller, Joerg C

2017-01-01

The properties of enzymes can be altered significantly by modification with polymers. Numerous different methods are known to obtain such polymer-enzyme conjugates (PECs). However, there is no universal method to render enzymes into PECs that are fully soluble in organic solvents. Here, we present a method, which achieves such high degree of modification of proteins that the majority of modified enzymes will be soluble in organic solvents. This is achieved by preparing poly(2-alkyloxazoline)s (POx) with an NH 2 end group and coupling this functional polymer via pyromellitic acid dianhydride onto the amino groups of the respective protein. The resulting PECs are capable of serving as surfactants for unmodified proteins, rendering the whole mixture organosoluble. Depending on the nature of the POx and the molecular weight and the nature of the enzyme, the PECs are soluble in chloroform or even toluene. Another advantage of this method is that the poly(2-alkyloxazoline) can be activated with the coupling agent and used for the enzyme conjugation without further purification. The POx-enzyme conjugates generated by this modification strategy show modulated catalytic activity in both, aqueous and organic, systems. © 2017 Elsevier Inc. All rights reserved.

Novel High Efficient Organic Photovoltaic Materials: Final Summary of Research

NASA Technical Reports Server (NTRS)

Sun, Sam

2002-01-01

The objectives and goals of this project were to investigate and develop high efficient, lightweight, and cost effective materials for potential photovoltaic applications, such as solar energy conversion or photo detector devices. Specifically, as described in the original project proposal, the target material to be developed was a block copolymer system containing an electron donating (or p-type) conjugated polymer block coupled to an electron withdrawing (or n-type) conjugated polymer block through a non-conjugated bridge unit. Due to several special requirements of the targeted block copolymer systems, such as electron donating and withdrawing substituents, conjugated block structures, processing requirement, stability requirement, size controllability, phase separation and self ordering requirement, etc., many traditional or commonly used block copolymer synthetic schemes are not suitable for this system. Therefore, the investigation and development of applicable and effective synthetic protocols became the most critical and challenging part of this project. During the entire project period, and despite the lack of a proposed synthetic polymer postdoctoral research associate due to severe shortage of qualified personnel in the field, several important accomplishments were achieved in this project and are briefly listed and elaborated. A more detailed research and experimental data is listed in the Appendix.

Designing interchain and intrachain properties of conjugated polymers for latent optical information encoding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, Kyeongwoon; McAllister, Andrew; Bilby, David

Building molecular-design insights for controlling both the intrachain and the interchain properties of conjugated polymers (CPs) is essential to determine their characteristics and to optimize their performance in applications. However, most CP designs have focused on the conjugated main chain to control the intrachain properties, while the design of side chains is usually used to render CPs soluble, even though the side chains critically affect the interchain packing. Here, we present a straightforward and effective design strategy for modifying the optical and electrochemical properties of diketopyrrolopyrrole-based CPs by controlling both the intrachain and interchain properties in a single system. Themore » synthesized polymers, P1, P2 and P3, show almost identical optical absorption spectra in solution, manifesting essentially the same intrachain properties of the three CPs having restricted effective conjugation along the main chain. However, the absorption spectra of CP films are gradually tuned by controlling the interchain packing through the side-chain design. Here, based on the tailored optical properties, we demonstrate the encoding of latent optical information utilizing the CPs as security inks on a silica substrate, which reveals and conceals hidden information upon the reversible aggregation/deaggregation of CPs.« less

On-line capillary electrophoresis-based enzymatic methodology for the study of polymer-drug conjugates.

PubMed

Coussot, G; Ladner, Y; Bayart, C; Faye, C; Vigier, V; Perrin, C

2015-01-09

This work aims at studying the potentialities of an on-line capillary electrophoresis (CE)-based digestion methodology for evaluating polymer-drug conjugates degradability in the presence of free trypsin (in-solution digestion). A sandwich plugs injection scheme with transverse diffusion of laminar profile (TDLFP) mode was used to achieve on-line digestions. Electrophoretic separation conditions were established using poly-l-Lysine (PLL) as reference substrate. Comparison with off-line digestion was carried out to demonstrate the feasibility of the proposed methodology. The applicability of the on-line CE-based digestion methodology was evaluated for two PLL-drug conjugates and for the four first generations of dendrigraft of lysine (DGL). Different electrophoretic profiles presenting the formation of di, tri, and tetralysine were observed for PLL-drug and DGL. These findings are in good agreement with the nature of the linker used to link the drug to PLL structure and the predicted degradability of DGL. The present on-line methodology applicability was also successfully proven for protein conjugates hydrolysis. In summary, the described methodology provides a powerful tool for the rapid study of biodegradable polymers. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhanced stability of L-asparaginase by its bioconjugation to poly(styrene-co-maleic acid) and Ecoflex nanoparticles.

PubMed

Varshosaz, Jaleh; Anvari, Negin

2018-06-01

Acute lymphoblastic leukemia (ALL) is the white blood cell cancer in children. L-asparaginase (L-ASNase) is one of the first drugs used in ALL treatment. Anti-tumor activity of L-ASNase is not specific and indicates limited stability in different biological environments, in addition to its quick clearance from blood. The purpose of the present study was to achieve a new L-ASNase polymer bioconjugate to improve pharmacokinetic, increase half-life and stability of the enzyme. The conjugations were achieved by the cross-linking agent of 1-ethyl-3-(3- dimethylaminopropyl) carbodiimide (EDC) which activates the carboxylic acid groups of polymeric nanoparticles to create amide bond. EDC conjugated the L-ASNase to two biodegradable polymers including; Ecoflex ® and poly (styrene-co-maleic acid) (PSMA) nanoparticles. To achieve optimal L-ASNase nanoparticles the amounts of each polymer and the crosslinker were optimized and the nanoparticles were characterized according to their particle size, zeta potential and percent of conjugation of the enzyme. The results showed that conjugated enzyme had more stability against pH changes and proteolysis. It had lower Km value (indicating more affinity to the substrate) and greater half-life in plasma and phosphate buffered saline, in comparison to native enzyme. Generally, the conjugated enzyme to PSMA nanoparticles showed greater results than Ecoflex ® nanoparticles.

Macromolecular therapeutics.

PubMed

Yang, Jiyuan; Kopeček, Jindřich

2014-09-28

This review covers water-soluble polymer-drug conjugates and macromolecules that possess biological activity without attached low molecular weight drugs. The main design principles of traditional and backbone degradable polymer-drug conjugates as well as the development of a new paradigm in nanomedicines - (low molecular weight) drug-free macromolecular therapeutics are discussed. To address the biological features of cancer, macromolecular therapeutics directed to stem/progenitor cells and the tumor microenvironment are deliberated. Finally, the future perspectives of the field are briefly debated. Copyright © 2014 Elsevier B.V. All rights reserved.

High-Sensitivity Conjugated Polymer/Nanoparticle Nanocomposites for Infrared Sensor Applications

DTIC Science & Technology

2011-03-03

Performances of Photovoltaic devices base d on Thieno[3,4-c] pyrrole -4,6-dione-Based Donor-Acceptor Conjugated Polymers and CdSe Tetrapods Abstract: We...2-yl)thieno[3,2-b] thiophene and thieno[3,4-c] pyrrole -4,6-dione units. The AM1.5 power conversion efficiency of a photovoltaic device containing...photovoltaic devices because of their readily tunable electronic properties. The electron-deficient thieno[3,4-c] pyrrole -4,6-dione (TPD) moiety exhibits a

Ultrafast polarisation spectroscopy of photoinduced charges in a conjugated polymer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakulin, A A; Loosdrecht, P van; Pshenichnikov, M S

2009-07-31

Tunable optical parametric generators and amplifiers (OPA), proposed and developed by Akhmanov and his colleagues, have become the working horses in exploration of dynamical processes in physics, chemistry, and biology. In this paper, we demonstrate the possibility of using ultrafast polarisation-sensitive two-colour spectroscopy, performed with a set of two OPAs, to study charge photogeneration and transport in conjugated polymers and their donor-acceptor blends. (special issue devoted to the 80th birthday of S.A. Akhmanov)

Photochemical approaches to ordered polymers

NASA Technical Reports Server (NTRS)

Meador, Michael A.; Abdulaziz, Mahmoud; Meador, Mary Ann B.

1990-01-01

The photocyclization of o-benzyloxyphenyl ketone chromophores provides an efficient, high yield route to the synthesis of 2,3-diphenylbenzofurans. The synthesis and solution of photochemistry of a series of polymers containing this chromophore is described. The photocuring of these polymers is a potential new approach to the synthesis of highly conjugated polymers based upon a p-phenylene bisbenzofuran repeat unit.

Theory of exciton transfer and diffusion in conjugated polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barford, William, E-mail: william.barford@chem.ox.ac.uk; Tozer, Oliver Robert; University College, University of Oxford, Oxford OX1 4BH

We describe a theory of Förster-type exciton transfer between conjugated polymers. The theory is built on three assumptions. First, we assume that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, and described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω < J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. The resulting expression for themore » exciton transfer rate has a familiar form, being a function of the exciton transfer integral and the effective Franck-Condon factors. The effective Franck-Condon factors are functions of the effective Huang-Rhys parameters, which are inversely proportional to the chromophore size. The Born-Oppenheimer expressions were checked against DMRG calculations, and are found to be within 10% of the exact value for a tiny fraction of the computational cost. This theory of exciton transfer is then applied to model exciton migration in conformationally disordered poly(p-phenylene vinylene). Key to this modeling is the assumption that the donor and acceptor chromophores are defined by local exciton ground states (LEGSs). Since LEGSs are readily determined by the exciton center-of-mass wavefunction, this theory provides a quantitative link between polymer conformation and exciton migration. Our Monte Carlo simulations indicate that the exciton diffusion length depends weakly on the conformation of the polymer, with the diffusion length increasing slightly as the chromophores became straighter and longer. This is largely a geometrical effect: longer and straighter chromophores extend over larger distances. The calculated diffusion lengths of ∼10 nm are in good agreement with experiment. The spectral properties of the migrating excitons are also investigated. The emission intensity ratio of the 0-0 and 0-1 vibronic peaks is related to the effective Huang-Rhys parameter of the emitting state, which in turn is related to the chromophore size. The intensity ratios calculated from the effective Huang-Rhys parameters are in agreement with experimental spectra, and the time-resolved trend for the intensity ratio to decrease with time was also reproduced as the excitation migrates to shorter, lower energy chromophores as a function of time. In addition, the energy of the exciton state shows a logarithmic decrease with time, in agreement with experimental observations.« less

Theory of exciton transfer and diffusion in conjugated polymers.

PubMed

Barford, William; Tozer, Oliver Robert

2014-10-28

We describe a theory of Förster-type exciton transfer between conjugated polymers. The theory is built on three assumptions. First, we assume that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, and described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω < J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. The resulting expression for the exciton transfer rate has a familiar form, being a function of the exciton transfer integral and the effective Franck-Condon factors. The effective Franck-Condon factors are functions of the effective Huang-Rhys parameters, which are inversely proportional to the chromophore size. The Born-Oppenheimer expressions were checked against DMRG calculations, and are found to be within 10% of the exact value for a tiny fraction of the computational cost. This theory of exciton transfer is then applied to model exciton migration in conformationally disordered poly(p-phenylene vinylene). Key to this modeling is the assumption that the donor and acceptor chromophores are defined by local exciton ground states (LEGSs). Since LEGSs are readily determined by the exciton center-of-mass wavefunction, this theory provides a quantitative link between polymer conformation and exciton migration. Our Monte Carlo simulations indicate that the exciton diffusion length depends weakly on the conformation of the polymer, with the diffusion length increasing slightly as the chromophores became straighter and longer. This is largely a geometrical effect: longer and straighter chromophores extend over larger distances. The calculated diffusion lengths of ~10 nm are in good agreement with experiment. The spectral properties of the migrating excitons are also investigated. The emission intensity ratio of the 0-0 and 0-1 vibronic peaks is related to the effective Huang-Rhys parameter of the emitting state, which in turn is related to the chromophore size. The intensity ratios calculated from the effective Huang-Rhys parameters are in agreement with experimental spectra, and the time-resolved trend for the intensity ratio to decrease with time was also reproduced as the excitation migrates to shorter, lower energy chromophores as a function of time. In addition, the energy of the exciton state shows a logarithmic decrease with time, in agreement with experimental observations.

Grafting PNIPAAm from β-barrel shaped transmembrane nanopores.

PubMed

Charan, Himanshu; Kinzel, Julia; Glebe, Ulrich; Anand, Deepak; Garakani, Tayebeh Mirzaei; Zhu, Leilei; Bocola, Marco; Schwaneberg, Ulrich; Böker, Alexander

2016-11-01

The research on protein-polymer conjugates by grafting from the surface of proteins has gained significant interest in the last decade. While there are many studies with globular proteins, membrane proteins have remained untouched to the best of our knowledge. In this study, we established the conjugate formation with a class of transmembrane proteins and grow polymer chains from the ferric hydroxamate uptake protein component A (FhuA; a β-barrel transmembrane protein of Escherichia coli). As the lysine residues of naturally occurring FhuA are distributed over the whole protein, FhuA was reengineered to have up to 11 lysines, distributed symmetrically in a rim on the membrane exposed side (outside) of the protein channel and exclusively above the hydrophobic region. Reengineering of FhuA ensures a polymer growth only on the outside of the β-barrel and prevents blockage of the channel as a result of the polymerization. A water-soluble initiator for controlled radical polymerization (CRP) was consecutively linked to the lysine residues of FhuA and N-isopropylacrylamide (NIPAAm) polymerized under copper-mediated CRP conditions. The conjugate formation was analyzed by using MALDI-ToF mass spectrometry, SDS-PAGE, circular dichroism spectroscopy, analytical ultracentrifugation, dynamic light scattering, transmission electron microscopy and size exclusion chromatography. Such conjugates combine the specific functions of the transmembrane proteins, like maintaining membrane potential gradients or translocation of substrates with the unique properties of synthetic polymers such as temperature and pH stimuli handles. FhuA-PNIPAAm conjugates will serve as functional nanosized building blocks for applications in targeted drug delivery, self-assembly systems, functional membranes and transmembrane protein gated nanoreactors. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chemical and charge transfer studies on interfaces of a conjugated polymer and ITO

NASA Astrophysics Data System (ADS)

David, Tanya M. S.; Arasho, Wondwosson; Smith, O'Neil; Hong, Kunlun; Bonner, Carl; Sun, Sam-Shajing

2017-08-01

Conjugated oligomers and polymers are very attractive for potential future plastic electronic and opto-electronic device applications such as plastic photo detectors and solar cells, thermoelectric devices, field effect transistors, and light emitting diodes. Understanding and optimizing charge transport between an active polymer layer and conductive substrate is critical to the optimization of polymer based electronic and opto-electronic devices. This study focused on the design, synthesis, self-assembly, and electron transfers and transports of a phosphonic acid end-functionalized polyphenylenevinylene (PPV) that was covalently attached and self-assembled onto an Indium Tin Oxide (ITO) substrate. This study demonstrated how atomic force microscopy (AFM) can be an effective characterization technique in conjunction with conventional electron transfer methods, including cyclic voltammetry (CV), towards determining electron transfer rates in polymer and polymer/conductor interface systems. This study found that the electron transfer rates of covalently attached and self-assembled films were much faster than the spin coated films. The knowledge from this study can be very useful for designing potential polymer based electronic and opto-electronic thin film devices.

Synthesis of π-conjugated polymer consisting of pyrrole and fluorene units by Ru-catalyzed site-selective direct arylation polycondensation.

PubMed

Lu, Wei; Kuwabara, Junpei; Kanbara, Takaki

2013-07-25

Polycondensation of 1-(2-pyrimidinyl)pyrrole with 2,7-dibromo-9,9-dioctylfluorene via Ru-catalyzed direct arylation gives the corresponding conjugated polymer with a molecular weight of 19 800 in 86% yield. The introduction of directing group, 2-pyrimidinyl substituent, into the pyrrole monomer induces ortho-metalation and provides the site-selective direct arylation polycondensation at the α-position of pyrrole unit without the protection of β-position. The removal of 2-pyrimidinyl substituent on the pyrrole unit proceeds efficiently and results in the enhancement of coplanarity along the main chain of the polymer. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

FAST TRACK COMMUNICATION: High material efficiency found in electrophoretic deposition of conjugated polymer

NASA Astrophysics Data System (ADS)

Tada, Kazuya; Onoda, Mitsuyoshi

2009-09-01

The material efficiency of electrophoretic deposition of a fluorene-based conjugated polymer, poly[(9,9-dioctyl-2,7-divinylenefluorenylene)-alt-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}] (PDOF-MEHPV), from suspensions with a mixture of acetonitrile and toluene as dispersant is studied. It has been found that the recovery rate of the electrophoretic deposition from a suspension containing 90% of the poor solvent acetonitrile reaches 98%. Although the recovery rate decreases with decreasing acetonitrile content, almost 70% of the polymer can be deposited on the substrates from the suspension containing equivalent volumes of the good and poor solvents by electrophoretic deposition, from which smooth and transparent films suitable for electronic devices are obtained.

Poly(methyl vinyl ether-alt-maleic acid)-functionalized porous silicon nanoparticles for enhanced stability and cellular internalization.

PubMed

Shahbazi, Mohammad-Ali; Almeida, Patrick V; Mäkilä, Ermei; Correia, Alexandra; Ferreira, Mónica P A; Kaasalainen, Martti; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

2014-03-01

Currently, developing a stable nanocarrier with high cellular internalization and low toxicity is a key bottleneck in nanomedicine. Here, we have developed a successful method to covalently conjugate poly(methyl vinyl ether-co-maleic acid) (PMVE-MA) copolymer on the surface of (3-aminopropyl)triethoxysilane-functionalized thermally carbonized porous silicon nanoparticles (APSTCPSi NPs), forming a surface negatively charged nanovehicle with unique properties. This polymer conjugated NPs could modify surface smoothness, charge, and hydrophilicity of the developed NPs, leading to considerable improvement in the colloidal and plasma stabilities via enhanced suspensibility and charge repulsion. Furthermore, despite the surface negative charge of the polymer-conjugated NPs, the cellular internalization was increased in both MDA-MB-231 and MCF-7 breast cancer cells. These results provide a proof-of-concept evidence that such polymer-based PSi nanocomposite can be extensively used as a promising candidate for intracellular drug delivery. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymer therapeutics at a crossroads? Finding the path for improved translation in the twenty-first century.

PubMed

Duncan, Ruth

Despite the relatively small early investment, first generation 'polymer therapeutics' have been remarkably successful with more than 25 products licenced for human use as polymeric drugs, sequestrants, conjugates, and as an imaging agent. Many exhibit both clinical and commercial success with new concepts already in clinical trials. Nevertheless after four decades of evolution, this field is arriving at an important crossroads. Over the last decade, the landscape has changed rapidly. There are an increasing number of failed clinical trials, the number of 'copy' and 'generic' products is growing (danger of ignoring the biological rationale for design and suppression of innovation), potential drawbacks of PEG are becoming more evident, and the 'nanomedicine' boom has brought danger of loss of scientific focus/hype. Grasping opportunities provided by advances in understanding of the patho-physiology and molecular basis of diseases, new polymer/conjugate synthetic and analytical methods, as well as the large database of clinical experience will surely ensure a successful future for innovative polymer therapeutics. Progress will, however, be in jeopardy if polymer safety is overlooked in respect of the specific route of administration/clinical use, poorly characterised materials/formulations are used to define biological or early clinical properties, and if clinical trial protocols fail to select patients most likely to benefit from these macromolecular therapeutics. Opportunities to improve clinical trial design for polymer-anticancer drug conjugates are discussed. This short personal perspective summarises some of the important challenges facing polymer therapeutics in R&D today, and future opportunities to improve successful translation.

Novel Effects of Compressed CO 2 Molecules on Structural Ordering and Charge Transport in Conjugated Poly(3-hexylthiophene) Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Naisheng; Sendogdular, Levent; Sen, Mani

We report the effects of compressed CO 2 molecules as a novel plasticization agent for poly(3- hexylthiophene) (P3HT) conjugated polymer thin films. In-situ neutron reflectivity experiment demonstrated the excess sorption of CO 2 molecules in the P3HT thin films (about 40 nm in thickness) at low pressure (P = 8.2 MPa) under the isothermal condition of T = 36 °C, which is far below the polymer bulk melting point. The results evidenced that these CO 2 molecules accelerated the crystallization process of the polymer on the basis of ex-situ grazing incidence Xray diffraction measurements after drying the films via rapidmore » depressurization to atmospheric pressure: not only the out-of-plane lamellar ordering of the backbone chains but also intra-plane π-π stacking of the side chains were significantly improved, when compared to those in the control P3HT films subjected to conventional thermal annealing (at T = 170 °C). Electrical measurements elucidated that the CO 2-annealed P3HT thin films exhibited enhanced charge carrier mobility along with decreased background charge carrier concentration and trap density compared to those in the thermally annealed counterpart. This is attributed to the CO 2-induced increase in polymer chain mobility that can drive the detrapping of molecular oxygen and healing of conformational defects in the polymer thin film. Given the universality of the excess sorption of CO 2regardless of the type of polymers, the present findings suggest that the CO 2 annealing near the critical point can be useful as a robust processing strategy for improving structural and electrical characteristics of other semiconducting conjugated polymers and related systems such as polymer: fullerene bulk heterojunction films.tion films.« less

Novel Effects of Compressed CO 2 Molecules on Structural Ordering and Charge Transport in Conjugated Poly(3-hexylthiophene) Thin Films

DOE PAGES

Jiang, Naisheng; Sendogdular, Levent; Sen, Mani; ...

2016-10-06

We report the effects of compressed CO 2 molecules as a novel plasticization agent for poly(3- hexylthiophene) (P3HT) conjugated polymer thin films. In-situ neutron reflectivity experiment demonstrated the excess sorption of CO 2 molecules in the P3HT thin films (about 40 nm in thickness) at low pressure (P = 8.2 MPa) under the isothermal condition of T = 36 °C, which is far below the polymer bulk melting point. The results evidenced that these CO 2 molecules accelerated the crystallization process of the polymer on the basis of ex-situ grazing incidence Xray diffraction measurements after drying the films via rapidmore » depressurization to atmospheric pressure: not only the out-of-plane lamellar ordering of the backbone chains but also intra-plane π-π stacking of the side chains were significantly improved, when compared to those in the control P3HT films subjected to conventional thermal annealing (at T = 170 °C). Electrical measurements elucidated that the CO 2-annealed P3HT thin films exhibited enhanced charge carrier mobility along with decreased background charge carrier concentration and trap density compared to those in the thermally annealed counterpart. This is attributed to the CO 2-induced increase in polymer chain mobility that can drive the detrapping of molecular oxygen and healing of conformational defects in the polymer thin film. Given the universality of the excess sorption of CO 2regardless of the type of polymers, the present findings suggest that the CO 2 annealing near the critical point can be useful as a robust processing strategy for improving structural and electrical characteristics of other semiconducting conjugated polymers and related systems such as polymer: fullerene bulk heterojunction films.tion films.« less

Displacement of polarons by vibrational modes in doped conjugated polymers

NASA Astrophysics Data System (ADS)

Anderson, M.; Ramanan, C.; Fontanesi, C.; Frick, A.; Surana, S.; Cheyns, D.; Furno, M.; Keller, T.; Allard, S.; Scherf, U.; Beljonne, D.; D'Avino, G.; von Hauff, E.; Da Como, E.

2017-10-01

Organic pi-conjugated polymers are deemed to be soft materials with strong electron-phonon coupling, which results in the formation of polarons, i.e., charge carriers dressed by self-localized distortion of the nuclei. Universal signatures for polarons are optical resonances below the band gap and intense vibrational modes (IVMs), both found in the infrared (IR) spectral region. Here, we study p -doped conjugated homo- and copolymers by combining first-principles modelling and optical spectroscopy from the far-IR to the visible. Polaronic IVMs are found to feature absorption intensities comparable to purely electronic transitions and, most remarkably, show only loose resemblance to the Raman or IR-active modes of the neutral polymer. The IVM frequency is dramatically scaled down (up to 50%) compared to the backbone carbon-stretching modes in the pristine polymers. The very large intensity of IVMs is associated with displacement of the excess positive charge along the backbone driven by specific vibrational modes. We propose a quantitative picture for the identification of these polaron shifting modes that solely based on structural information, directly correlates with their IR intensity. This finding finally discloses the elusive microscopic mechanism behind the huge IR intensity of IVMs in doped polymeric semiconductors.

Envisioning the future of polymer therapeutics for brain disorders.

PubMed

Rodriguez-Otormin, Fernanda; Duro-Castano, Aroa; Conejos-Sánchez, Inmaculada; Vicent, María J

2018-06-14

The growing incidence of brain-related pathologies and the problems that undermine the development of efficient and effective treatments have prompted both researchers and the pharmaceutical industry to search for novel therapeutic alternatives. Polymer therapeutics (PT) display properties well suited to the treatment of neuro-related disorders, which help to overcome the many hidden obstacles on the journey to the central nervous system (CNS). The inherent features of PT, derived from drug(s) conjugation, in parallel with the progress in synthesis and analytical methods, the increasing knowledge in molecular basis of diseases, and collected clinical data through the last four decades, have driven the translation from "bench to bedside" for various biomedical applications. However, since the approval of Gliadel® wafers, little progress has been made in the CNS field, even though brain targeting represents an ever-growing challenge. A thorough assessment of the steps required for successful brain delivery via different administration routes and the consideration of the disease-specific hallmarks are essential to progress in the field. Within this review, we hope to summarize the latest developments, successes, and failures and discuss considerations on designs and strategies for PT in the treatment of CNS disorders. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease. © 2018 Wiley Periodicals, Inc.

Photo-induced conjugation of tetrazoles to modified and native proteins.

PubMed

Siti, Winna; Khan, Amit Kumar; de Hoog, Hans-Peter M; Liedberg, Bo; Nallani, Madhavan

2015-03-21

Bio-orthogonal chemistry has been widely used for conjugation of polymer molecules to proteins. Here, we demonstrate the conjugation of polyethylene glycol (PEG) to bovine beta-lactoglobulin (BLG) by photo-induced cyclo-addition of tetrazole-appended PEG and allyl-modified BLG. During the course of the investigation, a significant side-reaction was found to occur for the conjugation of PEG-tetrazole to native BLG. Further exploration of the underlying chemistry reveals that the presence of a tryptophan residue is sufficient for conjugation of tetrazole-modified molecules.

Conjugated polymer sensors built on pi-extended borasiloxane cages.

PubMed

Liu, Wenjun; Pink, Maren; Lee, Dongwhan

2009-06-24

An efficient 2 + 2 cyclocondensation with dihydroxysilane converted simple arylboronic acids to bifunctional borasiloxane cage molecules, which were subsequently electropolymerized to furnish air-stable thin films. The extended [p,pi]-conjugation that defines the rigid backbone of this new conjugated polymer (CP) motif gives rise to longer-wavelength UV-vis transitions upon oxidative doping, the spectral window and intensity of which can be modified by interaction with Lewis basic reagents. Notably, this boron-containing CP undergoes a rapid and reversible color change from green to orange upon exposure to volatile amine samples under ambient conditions. This direct naked-eye detection scheme can best be explained by invoking the reversible B-N dative bond formation that profoundly influences the p-pi* orbital overlap.

Semiconductor-nanocrystal/conjugated polymer thin films

DOEpatents

Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

2014-06-17

The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

Semiconductor-nanocrystal/conjugated polymer thin films

DOEpatents

Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

2010-08-17

The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

Singlet and triplet energy transfer in a benzil-doped, light emitting, solid-state conjugated polymer

NASA Astrophysics Data System (ADS)

Rothe, C.; Pålsson, L. O.; Monkman, A. P.

2002-12-01

The luminescence emitted from pure and benzil-doped thin films of the conjugated polymer polyfluorene [PF2/6] are compared. The prompt fluorescence from the first singlet-excited state of the polymer is quenched by 90% in the presence of 10% per weight benzil. In addition to the prompt fluorescence, time-resolved spectroscopy at low temperature also allows the detection of phosphorescence and delayed fluorescence from the host polymer. Again the delayed fluorescence is strongly quenched but the phosphorescence is enhanced in doped samples. An explanation of the results is given in terms of singlet energy transfer from the host to benzil and triplet energy transfer from the dopant back to PF2/6. We have applied this to enable better understanding of the photophysics in PF2/6 doped with a platinum porphyrin complex.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuan, Tao; Zhu, Xiaoguang; Tu, Guoli, E-mail: tgl@hust.edu.cn

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

Controlled Pd(0)/t Bu3P Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with ArPd(t Bu3P)X or Pd2(dba)3/t Bu3P/ArX as the Initiator

DOE PAGES

Zhang, Honghai; Xing, Chun-Hui; Hu, Qiao-Sheng; ...

2015-02-05

The synthesis of well-defined and functionalized conjugated polymers, which are essential in the development of efficient organic electronics, through Suzuki cross-coupling polymerizations has been a challenging task. We developed controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with a series of in situ generated ArPd(t-Bu3P)X (X = I, Br, Cl) complexes as initiators. Among them, the combinations of Pd2(dba)3/t-Bu3P/p-BrC6H4I, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br were identified as highly robust initiator systems, resulting in polymers with predictable molecular weight and narrow polydispersity (PDI~1.13-1.20). In addition, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br initiator systems afforded functional polymers with >95% fidelity. Our results pavedmore » the road to access well-defined conjugated polymers, including conjugated polymers with complex polymer architectures such as block copolymers and branch copolymers.« less

Pectin-cysteine conjugate: synthesis and in-vitro evaluation of its potential for drug delivery.

PubMed

Majzoob, Sayeh; Atyabi, Fatemeh; Dorkoosh, Farid; Kafedjiiski, Krum; Loretz, Brigitta; Bernkop-Schnürch, Andreas

2006-12-01

This study was aimed at improving certain properties of pectin by introduction of thiol moieties on the polymer. Thiolated pectin was synthesized by covalent attachment of cysteine. Pectin-cysteine conjugate was evaluated for its ability to be degraded by pectinolytic enzyme. The toxicity profile of the thiolated polymer in Caco-2-cells, its permeation enhancing effect and its mucoadhesive and swelling properties were studied. Moreover insulin-loaded hydrogel beads of the new polymer were examined for their stability in simulated gastrointestinal conditions and their drug release profile. The new polymer displayed 892.27 +/- 68.68 micromol thiol groups immobilized per g polymer, and proved to have retained its biodegradability, upon addition of Pectinex Ultra SPL in-vitro, determined by viscosity measurements and titration method. Pectin-cysteine showed no severe toxicity in Caco-2 cells, as tested by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Moreover, the synthesized polymer exhibited a relative permeation enhancement ratio of 1.61 for sodium fluorescein, compared to unmodified pectin. Pectin-cysteine conjugate exhibited approximately 5-fold increased in in-vitro adhesion duration and significantly improved cohesive properties. Zinc pectin-cysteine beads showed improved stability in simulated gastrointestinal media; however, insulin release from these beads followed the same profile as unmodified zinc pectinate beads. Due to favourable safety and biodegradability profile, and improved cohesive and permeation-enhancing properties, pectin-cysteine might be a promising excipient in various transmucosal drug delivery systems.

Quantum dot-polymer conjugates for stable luminescent displays.

PubMed

Ghimire, Sushant; Sivadas, Anjaly; Yuyama, Ken-Ichi; Takano, Yuta; Francis, Raju; Biju, Vasudevanpillai

2018-05-23

The broad absorption of light in the UV-Vis-NIR region and the size-based tunable photoluminescence color of semiconductor quantum dots make these tiny crystals one of the most attractive antennae in solar cells and phosphors in electrooptical devices. One of the primary requirements for such real-world applications of quantum dots is their stable and uniform distribution in optically transparent matrices. In this work, we prepare transparent thin films of polymer-quantum dot conjugates, where CdSe/ZnS quantum dots are uniformly distributed at high densities in a chitosan-polystyrene copolymer (CS-g-PS) matrix. Here, quantum dots in an aqueous solution are conjugated to the copolymer by a phase transfer reaction. With the stable conjugation of quantum dots to the copolymer, we prevent undesired phase separation between the two and aggregation of quantum dots. Furthermore, the conjugate allows us to prepare transparent thin films in which quantum dots are uniformly distributed at high densities. The CS-g-PS copolymer helps us in not only preserving the photoluminescence properties of quantum dots in the film but also rendering excellent photostability to quantum dots at the ensemble and single particle levels, making the conjugate a promising material for photoluminescence-based devices.

Multivalency of Sonic hedgehog conjugated to linear polymer chains modulates protein potency.

PubMed

Wall, Samuel T; Saha, Krishanu; Ashton, Randolph S; Kam, Kimberly R; Schaffer, David V; Healy, Kevin E

2008-04-01

A potently active multivalent form of the protein Sonic hedgehog (Shh) was produced by bioconjugation of a modified recombinant form of Shh to the linear polymers poly(acrylic acid) (pAAc) and hyaluronic acid (HyA) via a two-step reaction exploiting carboimiide and maleimide chemistry. Efficiency of the conjugation was approximately 75% even at stoichiometric ratios of 30 Shh molecules per linear HyA chain (i.e., 30:1 Shh/HyA). Bioactivity of the conjugates was tested via a cellular assay across a range of stoichiometric ratios of Shh molecules to HyA linear chains, which was varied from 0.6:1 Shh/HyA to 22:1 Shh/HyA. Results indicate that low conjugation ratios decrease Shh bioactivity and high ratios increase this activity beyond the potency of monomeric Shh, with approximately equal activity between monomeric soluble Shh and conjugated Shh at 7:1 Shh/HyA. In addition, high-ratio constructs increased angiogenesis determined by the in vivo chick chorioallantoic membrane (CAM) assay. These results are captured by a kinetic model of multiple interactions between the Shh/HyA conjugates and cell surface receptors resulting in higher cell signaling at lower bulk Shh concentrations.

Aggregation control in natural brush-printed conjugated polymer films and implications for enhancing charge transport

PubMed Central

Wang, Gang; Huang, Wei; Eastham, Nicholas D.; Fabiano, Simone; Manley, Eric F.; Zeng, Li; Wang, Binghao; Zhang, Xinan; Chen, Zhihua; Li, Ran; Chang, Robert P. H.; Chen, Lin X.; Bedzyk, Michael J.; Melkonyan, Ferdinand S.; Facchetti, Antonio; Marks, Tobin J.

2017-01-01

Shear-printing is a promising processing technique in organic electronics for microstructure/charge transport modification and large-area film fabrication. Nevertheless, the mechanism by which shear-printing can enhance charge transport is not well-understood. In this study, a printing method using natural brushes is adopted as an informative tool to realize direct aggregation control of conjugated polymers and to investigate the interplay between printing parameters, macromolecule backbone alignment and aggregation, and charge transport anisotropy in a conjugated polymer series differing in architecture and electronic structure. This series includes (i) semicrystalline hole-transporting P3HT, (ii) semicrystalline electron-transporting N2200, (iii) low-crystallinity hole-transporting PBDTT-FTTE, and (iv) low-crystallinity conducting PEDOT:PSS. The (semi-)conducting films are characterized by a battery of morphology and microstructure analysis techniques and by charge transport measurements. We report that remarkably enhanced mobilities/conductivities, as high as 5.7×/3.9×, are achieved by controlled growth of nanofibril aggregates and by backbone alignment, with the adjusted R2 (R2adj) correlation between aggregation and charge transport as high as 95%. However, while shear-induced aggregation is important for enhancing charge transport, backbone alignment alone does not guarantee charge transport anisotropy. The correlations between efficient charge transport and aggregation are clearly shown, while mobility and degree of orientation are not always well-correlated. These observations provide insights into macroscopic charge transport mechanisms in conjugated polymers and suggest guidelines for optimization. PMID:29109282

Towards the Development of a Low-Cost Device for the Detection of Explosives Vapors by Fluorescence Quenching of Conjugated Polymers in Solid Matrices.

PubMed

Martelo, Liliana M; das Neves, Tiago F Pimentel; Figueiredo, João; Marques, Lino; Fedorov, Alexander; Charas, Ana; Berberan-Santos, Mário N; Burrows, Hugh D

2017-11-03

Conjugated polymers (CPs) have proved to be promising chemosensory materials for detecting nitroaromatic explosives vapors, as they quickly convert a chemical interaction into an easily-measured high-sensitivity optical output. The nitroaromatic analytes are strongly electron-deficient, whereas the conjugated polymer sensing materials are electron-rich. As a result, the photoexcitation of the CP is followed by electron transfer to the nitroaromatic analyte, resulting in a quenching of the light-emission from the conjugated polymer. The best CP in our studies was found to be poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-bithiophene] (F8T2). It is photostable, has a good absorption between 400 and 450 nm, and a strong and structured fluorescence around 550 nm. Our studies indicate up to 96% quenching of light-emission, accompanied by a marked decrease in the fluorescence lifetime, upon exposure of the films of F8T2 in ethyl cellulose to nitrobenzene (NB) and 1,3-dinitrobenzene (DNB) vapors at room temperature. The effects of the polymeric matrix, plasticizer, and temperature have been studied, and the morphology of films determined by scanning electron microscopy (SEM) and confocal fluorescence microscopy. We have used ink jet printing to produce sensor films containing both sensor element and a fluorescence reference. In addition, a high dynamic range, intensity-based fluorometer, using a laser diode and a filtered photodiode was developed for use with this system.

Bis(thienothiophenyl) diketopyrrolopyrrole-based conjugated polymers with various branched alkyl side chains and their applications in thin-film transistors and polymer solar cells.

PubMed

Shin, Jicheol; Park, Gi Eun; Lee, Dae Hee; Um, Hyun Ah; Lee, Tae Wan; Cho, Min Ju; Choi, Dong Hoon

2015-02-11

New thienothiophene-flanked diketopyrrolopyrrole and thiophene-containing π-extended conjugated polymers with various branched alkyl side-chains were successfully synthesized. 2-Octyldodecyl, 2-decyltetradecyl, 2-tetradecylhexadecyl, 2-hexadecyloctadecyl, and 2-octadecyldocosyl groups were selected as the side-chain moieties and were anchored to the N-positions of the thienothiophene-flanked diketopyrrolopyrrole unit. All five polymers were found to be soluble owing to the bulkiness of the side chains. The thin-film transistor based on the 2-tetradecylhexadecyl-substituted polymer showed the highest hole mobility of 1.92 cm2 V(-1) s(-1) due to it having the smallest π-π stacking distance between the polymer chains, which was determined by grazing incidence X-ray diffraction. Bulk heterojunction polymer solar cells incorporating [6,6]-phenyl-C71-butyric acid methyl ester as the n-type molecule and the additive 1,8-diiodooctane (1 vol %) were also constructed from the synthesized polymers without thermal annealing; the device containing the 2-octyldodecyl-substituted polymer exhibited the highest power conversion efficiency of 5.8%. Although all the polymers showed similar physical properties, their device performance was clearly influenced by the sizes of the branched alkyl side-chain groups.

Optimized Electroactive Polymer Supercapacitors

DTIC Science & Technology

2014-09-08

Final 03/01/2012-05/15/2014 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER OPTIMIZED ELECTROACTIVE POLYMER SUPERCAPACITORS NA Sb. GRANT NUMBER N00014-12-1...highly electroactive, conjugated polymers as the active redox materials in electrochemical supercapacitors . Such materials include electrochemically...ethylenedioxythiophene) (PEDOT) for Type I or Type II supercapacitors , along with donor-acceptor-donor (D-A-D) polymers which provide reductive states for Type

Incorporating perylene moiety into poly(phenothiazine-co-bithiophene) backbone for higher charge transport.

PubMed

Tang, Weihua; Ke, Lin; Chen, Zhi-Kuan

2008-03-27

Low band gap pi-conjugated polymers composed of phenothiazine, bithiophene, and perylene moieties were prepared in high yields by using a palladium-catalyzed Suzuki coupling reaction. The polymers were characterized by NMR, gel permeation chromatography, and elemental analysis. The characterizations revealed that high-molecular weight (weight-average molecular weight up to 42,400 g/mol) polymers were thermally stable with a decomposition temperature in the region of 338-354 degrees C and their glass transition temperatures (Tg) ranging from 124 to 136 degrees C. All polymers demonstrated broad optical absorption in the region of 300-550 nm with efficient blue-green light emission. The absorption was broadened further (for ca. 50 nm) when the perylene moiety was incorporated. Cyclic voltammograms displayed that the p- and n-doping processes of all the polymers were partially reversible and that electrochemical band gaps were as low as -2.30 eV with the incorporation of a perylene moiety. The hole mobility of polymers was evaluated by using the space-charge-limited current model with a device structure of ITO/PEDOT:PSS/polymer/Ca. The results show that the incorporation of perylene is beneficial for improving the hole mobility of the conjugated polymers.

Symmetry Breaking in Side Chains Leading to Mixed Orientations and Improved Charge Transport in Isoindigo-alt-Bithiophene Based Polymer Thin Films.

PubMed

Xue, Guobiao; Zhao, Xikang; Qu, Ge; Xu, Tianbai; Gumyusenge, Aristide; Zhang, Zhuorui; Zhao, Yan; Diao, Ying; Li, Hanying; Mei, Jianguo

2017-08-02

The selection of side chains is important in design of conjugated polymers. It not only affects their intrinsic physical properties, but also has an impact on thin film morphologies. Recent reports suggested that a face-on/edge-on bimodal orientation observed in polymer thin films may be responsible for a three-dimensional (3D) charge transport and leads to dramatically improved mobility in donor-acceptor based conjugated polymers. To achieve a bimodal orientation in thin films has been seldom explored from the aspect of molecular design. Here, we demonstrate a design strategy involving the use of asymmetric side chains that enables an isoindigo-based polymer to adopt a distinct bimodal orientation, confirmed by the grazing incidence X-ray diffraction. As a result, the polymer presents an average high mobility of 3.8 ± 0.7 cm 2 V -1 s -1 with a maximum value of 5.1 cm 2 V -1 s -1 , in comparison with 0.47 and 0.51 cm 2 V -1 s -1 obtained from the two reference polymers. This study exemplifies a new strategy to develop the next generation polymers through understanding the property-structure relationship.

Development of Low Energy Gap and Fully Regioregular Polythienylenevinylene Derivative

DOE PAGES

David, Tanya M. S.; Zhang, Cheng; Sun, Sam-Shajing

2014-01-01

Low energy gap and fully regioregular conjugated polymers find its wide use in solar energy conversion applications. This paper will first briefly review this type of polymers and also report synthesis and characterization of a specific example new polymer, a low energy gap, fully regioregular, terminal functionalized, and processable conjugated polymer poly-(3-dodecyloxy-2,5-thienylene vinylene) or PDDTV. The polymer exhibited an optical energy gap of 1.46 eV based on the UV-vis-NIR absorption spectrum. The electrochemically measured highest occupied molecular orbital (HOMO) level is −4.79 eV, resulting in the lowest unoccupied molecular orbital (LUMO) level of −3.33 eV based on optical energy gap. The polymer wasmore » synthesized via Horner-Emmons condensation and is fairly soluble in common organic solvents such as tetrahydrofuran and chloroform with gentle heating. DSC showed two endothermic peaks at 67°C and 227°C that can be attributed to transitions between crystalline and liquid states. The polymer is thermally stable up to about 300°C. This polymer appears very promising for cost-effective solar cell applications.« less

Molecular engineered conjugated polymer with high thermal conductivity

PubMed Central

Song, Bai; Lee, Elizabeth M. Y.; Gleason, Karen K.

2018-01-01

Traditional polymers are both electrically and thermally insulating. The development of electrically conductive polymers has led to novel applications such as flexible displays, solar cells, and wearable biosensors. As in the case of electrically conductive polymers, the development of polymers with high thermal conductivity would open up a range of applications in next-generation electronic, optoelectronic, and energy devices. Current research has so far been limited to engineering polymers either by strong intramolecular interactions, which enable efficient phonon transport along the polymer chains, or by strong intermolecular interactions, which enable efficient phonon transport between the polymer chains. However, it has not been possible until now to engineer both interactions simultaneously. We report the first realization of high thermal conductivity in the thin film of a conjugated polymer, poly(3-hexylthiophene), via bottom-up oxidative chemical vapor deposition (oCVD), taking advantage of both strong C=C covalent bonding along the extended polymer chain and strong π-π stacking noncovalent interactions between chains. We confirm the presence of both types of interactions by systematic structural characterization, achieving a near–room temperature thermal conductivity of 2.2 W/m·K, which is 10 times higher than that of conventional polymers. With the solvent-free oCVD technique, it is now possible to grow polymer films conformally on a variety of substrates as lightweight, flexible heat conductors that are also electrically insulating and resistant to corrosion. PMID:29670943

Development of polymer-polysaccharide hydrogels for controlling drug delivery

NASA Astrophysics Data System (ADS)

Baldwin, Aaron David

The use of polymers as biomaterials has evolved over the past several decades, encompassing an expanding synthetic toolbox and many bio-mimetic approaches. Both synthetic and natural polymers have been used as components for biomaterials as their unique chemical structures can provide specific functions for desired applications. Of these materials, heparin, a highly sulfated naturally occurring polysaccharide, has been investigated extensively as a core component in drug delivery platforms and tissue engineering. The goal of this work was to further explore the use of heparin via conjugation with synthetic polymers for applications in drug delivery. We begin by investigating low molecular weight heparin (LMWH), a depolymerized heparin that is used medicinally in the prevention of thrombosis by subcutaneous injection or intravenous drip. Certain disease states or disorders require frequent administration with invasive delivery modalities leading to compliance issues for individuals on prolonged therapeutic courses. To address these issues, a long-term delivery method was developed for LMWH via subcutaneous injection of in situ hydrogelators. This therapy was accomplished by chemical modification of LMWH with maleimide functionality so that it may be crosslinked into continuous hydrogel networks with four-arm thiolated polyethylene glycol (PEG-SH). These hydrogels degrade via hydrolysis over a period of weeks and release bioactive LMWH with first-order kinetics as determined by in vitro and in vivo models, thus indicating the possibility of an alternative means of heparin delivery over current accepted methodologies. Evaluation of the maleimide-thiol chemistries applied in the LMWH hydrogels revealed reversibility for some conjugates under reducing conditions. Addition chemistries, such as maleimide-thiol reactions, are widely employed in biological conjugates and are generally accepted as stable. Here we show that the resulting succinimide thioether formed by the Michael type addition of thiol derivatives to N-ethylmaleimide (NEM) undergoes retro and exchange reactions in the presence of other thiol compounds at physiological pH and temperature. Model studies of NEM conjugated to various thiols (4-mercaptophenylacetic acid (MPA), N-acetylcysteine, or 3-mercaptopropionic acid (MP)), incubated with a naturally occurring reducing agent, glutathione, showed half-lives from 20-80 hrs with extents of conversion from 20-90% for MPA and N-acetylcysteine conjugates. The kinetics of the retro reactions and extent of exchange can be modulated by the Michael donor's reactivity; therefore the degradation of maleimide-thiol adducts could be tuned for controlled release of drugs or degradation of materials at timescales different than those currently possible via disulfide-mediated release. The reduction sensitive maleimide-thiol chemistry was then investigated as a crosslinking mechanism for LMWH hydrogels. Crosslinking maleimide functionalized LMWH with PEG functionalized with thiophenyl functionalities imparted glutathione sensitivity. 4-mercaptophenylpropionic acid and 2,2-dimethyl-3-(4-mercaptophenyl)propionic acid, induced sensitivity to glutathione as shown by a decrease in degradation time of 4x and 5x respectively. The pseudo-first order retro reaction constants were approximately an order of magnitude slower than hydrogels crosslinked via disulfide linkages, indicating the potential use of the retro succinimide-thioether covalent bonds for reduction mediated release and/or degradation with increased blood stability and prolonged drug delivery timescales compared to disulfide chemistries. In summary, this work highlights the use of polymer-polysaccharide hydrogels composed of LMWH and PEG as investigated for drug delivery and as a tool for elucidating a novel reduction sensitive controlled release mechanism.

Conjugated foldamers with unusually high space-charge-limited current hole mobilities.

PubMed

Li, Yong; Dutta, Tanmoy; Gerasimchuk, Nikolay; Wu, Shijie; Shetye, Kuldeep; Jin, Lu; Wang, Ruixin; Zhu, Da-Ming; Peng, Zhonghua

2015-05-13

Charge carrier mobility and its optimization play a critical role in the development of cutting-edge organic electronic and optoelectronic devices. Even though space-charge-limited current (SCLC) hole mobilities as high as 1.4 cm(2) V(-1) s(-1) have been reported for microscopically sized highly ordered liquid-crystalline conjugated small molecules, the SCLC hole mobility of device-sized thin films of conjugated polymers is still much lower, ranging from 10(-6) to 10(-3) cm(2) V(-1) s(-1). Herein, we report the synthesis, characterizations, and thin-film SCLC mobility of three discotic conjugated polymers, INDT-TT, INDT-BT, and INDT-NDT. Optical studies indicate that polymer INDT-NDT adopts a folded conformation in solutions of good or poor solvents, whereas polymer INDT-TT stays as random monomeric chains in good solvents and interchain aggregates in poor solvents. INDT-BT polymer chains, however, stay as foldamers in dilute solutions of good solvents but interchain aggregates in concentrated solutions or poor solvents. Circular dichroism spectroscopy provides clear evidence for the helical folding of INDT-NDT in solutions. Thin films spin-coated from 1,2-dichlorobenzene solutions of the polymers show SCLC hole mobility of 2.20 × 10(-6), 8.79 × 10(-5), and 2.77 × 10(-2) cm(2) V(-1) s(-1) for INDT-TT, INDT-BT, and INDT-NDT, respectively. HRTEM and powder XRD measurements show that INDT-NDT pristine thin films contain nanocrystalline domains, whereas the INDT-TT and INDT-BT films are amorphous. Thin films of INDT-NDT:PC71BM blends show increased crystallinity and further improved SCLC hole mobility up to 1.29 × 10(-1) cm(2) V(-1) s(-1), one of the highest SCLC mobility values ever recorded on solution-processed organic semiconducting thin films. The persistent folding conformation of INDT-NDT is believed to be responsible for the high crystallinity of its thin films and its high SCLC mobilities.

Optical Control of Living Cells Electrical Activity by Conjugated Polymers.

PubMed

Martino, Nicola; Bossio, Caterina; Vaquero Morata, Susana; Lanzani, Guglielmo; Antognazza, Maria Rosa

2016-01-28

Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications. In particular, conjugated polymers display several optimal properties as substrates for biological systems, such as good biocompatibility, excellent mechanical properties, cheap and easy processing technology, and possibility of deposition on light, thin and flexible substrates. These materials have been employed for cellular interfaces like neural probes, transistors for excitation and recording of neural activity, biosensors and actuators for drug release. Recent experiments have also demonstrated the possibility to use conjugated polymers for all-optical modulation of the electrical activity of cells. Several in-vitro study cases have been reported, including primary neuronal networks, astrocytes and secondary line cells. Moreover, signal photo-transduction mediated by organic polymers has been shown to restore light sensitivity in degenerated retinas, suggesting that these devices may be used for artificial retinal prosthesis in the future. All in all, light sensitive conjugated polymers represent a new approach for optical modulation of cellular activity. In this work, all the steps required to fabricate a bio-polymer interface for optical excitation of living cells are described. The function of the active interface is to transduce the light stimulus into a modulation of the cell membrane potential. As a study case, useful for in-vitro studies, a polythiophene thin film is used as the functional, light absorbing layer, and Human Embryonic Kidney (HEK-293) cells are employed as the biological component of the interface. Practical examples of successful control of the cell membrane potential upon stimulation with light pulses of different duration are provided. In particular, it is shown that both depolarizing and hyperpolarizing effects on the cell membrane can be achieved depending on the duration of the light stimulus. The reported protocol is of general validity and can be straightforwardly extended to other biological preparations.

Synthesis of Poly[APMA]-DOTA-64Cu conjugates for interventional radionuclide therapy of prostate cancer: assessment of intratumoral retention by micro-positron emission tomography.

PubMed

Yuan, Jianchao; You, Yezi; Lu, Xin; Muzik, Otto; Oupicky, David; Peng, Fangyu

2007-01-01

To develop new radiopharmaceuticals for interventional radionuclide therapy of locally recurrent prostate cancer, poly[N-(3-aminopropyl)methacrylamide] [poly(APMA)] polymers were synthesized by free radical precipitation polymerization in acetone-dimethylsulfoxide using N,N'-azobis(isobutyronitrile) as the initiator. The polymers were characterized with nuclear magnetic resonance, size exclusion chromatography, and dynamic light scattering (M(n) = 2.40 x 10(4), M(w)/M(n) = 1.87). Subsequently, poly[APMA] was coupled with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride as an activator, followed by conjugation with (64)Cu radionuclide. Prolonged retention of poly[APMA]-DOTA-(64)Cu conjugates within the tumor tissues was demonstrated by micro-positron emission tomography at 24 hours following intra-tumoral injection of the conjugates to human prostate xenografts in mice. The data suggest that the poly[APMA]-DOTA-(64)Cu conjugates might be useful for interventional radionuclide therapy of locally recurrent prostate cancer in humans.

CONJUGATED POLYMERS AND POLYELECTROLYTES IN SOLAR PHOTOCONVERSION, Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schanze, Kirk S

2014-08-05

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

Preactivated thiomers as mucoadhesive polymers for drug delivery

PubMed Central

Iqbal, Javed; Shahnaz, Gul; Dünnhaupt, Sarah; Müller, Christiane; Hintzen, Fabian; Bernkop-Schnürch, Andreas

2012-01-01

This study was aimed to synthesize polymeric excipients with improved mucoadhesive, cohesive and in situ-gelling properties to assure a prolonged retention time of dosage forms at a given target site, thereby achieving an increased uptake and improved oral bioavailability of certain challenging therapeutic agents such as peptides and proteins. Accordingly, poly(acrylic acid)-cysteine-2-mercaptonicotinic acid (PAA-cys-2MNA) conjugates were synthesized by the oxidative S–S coupling of PAA-cys (100-, 250- and 450 kDa) with 2-mercaptonicotinic acid (2MNA). Unmodified PAAs, PAAs-cys (thiomers) and PAA-cys-2MNA (100-, 250- and 450 kDa) conjugates were compressed into tablets to perform disintegration tests, mucoadhesion studies and rheological measurements. Moreover, cytotoxicty of the polymers was determined using Caco-2 cells. The resulting PAA-cys-2MNA (100-, 250- and 450 kDa) conjugates displayed 113.5 ± 12.7, 122.7 ± 12.2 and 117.3 ± 4.6 μmol/g of 2-mercaptonicotinic acid, respectively. Due to the immobilization of 2MNA, the PAA-cys-2MNA (pre-activated thiomers) conjugates exhibit comparatively higher swelling properties and disintegration time to the corresponding unmodified and thiolated polymers. On the rotating cylinder, tablets based on PAA-cys-2MNA (100-, 250- and 450 kDa) conjugates displayed 5.0-, 5.4- and 960-fold improved mucoadhesion time in comparison to the corresponding unmodified PAAs. Results achieved from tensile studies were found in good agreement with the results obtained by rotating cylinder method. The apparent viscosity of PAA-cys-2MNA (100-, 250- and 450 kDa) conjugates was improved 1.6-, 2.5- and 206.2-fold, respectively, in comparison to the corresponding unmodified PAAs. Moreover, pre-activated thiomers/mucin mixtures showed a time dependent increase in viscosity up to 24 h, leading to 7.0-, 18.9- and 2678-fold increased viscosity in comparison to unmodified PAAs (100-, 250- and 450 kDa), respectively. All polymers were found non-toxic over Caco-2 cells. Thus, on the basis of achieved results the pre-activated thiomers seem to represent a promising generation of mucoadhesive polymers which are safe to use for prolonged residence time of drug delivery systems to target various mucosa. PMID:22118819

Use of steric encumbrance to develop conjugated nanoporous polymers for metal-free catalytic hydrogenation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Chengcheng; Zhu, Xiang; Abney, Carter W.

The design and synthesis of metal-free heterogeneous catalysts for efficient hydrogenation remains a great challenge. Here we report a novel approach to create conjugated nanoporous polymers with efficient hydrogenation activities toward unsaturated ketones by leveraging the innate steric encumbrance. The steric bulk of the framework as well as the local sterics of the Lewis basic sites within the polymeric skeleton result in the generation of the putative catalyst. This approach opens up new possibilities for the development of innovative metal-free heterogeneous catalysts.

NIR-Mediated Nanohybrids of Upconversion Nanophosphors and Fluorescent Conjugated Polymers for High-Efficiency Antibacterial Performance Based on Fluorescence Resonance Energy Transfer.

PubMed

Li, Junting; Zhao, Qi; Shi, Feng; Liu, Chenghui; Tang, Yanli

2016-12-01

A novel nanohybrid comprised of upconversion nanophosphors (UCNPs) and fluorescent conjugated polymers (PFVCN) is rationally fabricated. The new UCNP/PFVCN nanohybrids combine the excellent antibacterial ability of PFVCN and the near IR (NIR) absorbing property of UCNPs, which allows for NIR-mediated antibacterial through the effective fluorescence resonance energy transfer from UCNPs to PFVCN accompanied with generation of reactive oxygen species to kill bacteria. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Use of steric encumbrance to develop conjugated nanoporous polymers for metal-free catalytic hydrogenation

DOE PAGES

Tian, Chengcheng; Zhu, Xiang; Abney, Carter W.; ...

2016-09-08

The design and synthesis of metal-free heterogeneous catalysts for efficient hydrogenation remains a great challenge. Here we report a novel approach to create conjugated nanoporous polymers with efficient hydrogenation activities toward unsaturated ketones by leveraging the innate steric encumbrance. The steric bulk of the framework as well as the local sterics of the Lewis basic sites within the polymeric skeleton result in the generation of the putative catalyst. Lastly, this approach opens up new possibilities for the development of innovative metal-free heterogeneous catalysts.

Use of steric encumbrance to develop conjugated nanoporous polymers for metal-free catalytic hydrogenation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Chengcheng; Zhu, Xiang; Abney, Carter W.

The design and synthesis of metal-free heterogeneous catalysts for efficient hydrogenation remains a great challenge. Here we report a novel approach to create conjugated nanoporous polymers with efficient hydrogenation activities toward unsaturated ketones by leveraging the innate steric encumbrance. The steric bulk of the framework as well as the local sterics of the Lewis basic sites within the polymeric skeleton result in the generation of the putative catalyst. Lastly, this approach opens up new possibilities for the development of innovative metal-free heterogeneous catalysts.

Blue Thermally Activated Delayed Fluorescence Polymers with Nonconjugated Backbone and Through-Space Charge Transfer Effect.

PubMed

Shao, Shiyang; Hu, Jun; Wang, Xingdong; Wang, Lixiang; Jing, Xiabin; Wang, Fosong

2017-12-13

We demonstrate novel molecular design for thermally activated delayed fluorescence (TADF) polymers based on a nonconjugated polyethylene backbone with through-space charge transfer effect between pendant electron donor (D) and acceptor (A) units. Different from conventional conjugated D-A polymers with through-bond charge transfer effect, the nonconjugated architecture avoids direct conjugation between D and A units, enabling blue emission. Meanwhile, spatial π-π interaction between the physically separated D and A units results in both small singlet-triplet energy splitting (0.019 eV) and high photoluminescence quantum yield (up to 60% in film state). The resulting polymer with 5 mol % acceptor unit gives efficient blue electroluminescence with Commission Internationale de l'Eclairage coordinates of (0.176, 0.269), together with a high external quantum efficiency of 12.1% and low efficiency roll-off of 4.9% (at 1000 cd m -2 ), which represents the first example of blue TADF nonconjugated polymer.

Anthracene-containing wide-band-gap conjugated polymers for high-open-circuit-voltage polymer solar cells.

PubMed

Gong, Xue; Li, Cuihong; Lu, Zhen; Li, Guangwu; Mei, Qiang; Fang, Tao; Bo, Zhishan

2013-07-25

The synthesis, characterization, and photophysical and photovoltaic properties of two anthracene-containing wide-band-gap donor and acceptor (D-A) alternating conjugated polymers (P1 and P2) are described. These two polymers absorb in the range of 300-600 nm with a band gap of about 2.12 eV. Polymer solar cells with P1:PC71 BM as the active layer demonstrate a power conversion efficiency (PCE) of 2.23% with a high Voc of 0.96 V, a Jsc of 4.4 mA cm(-2) , and a comparable fill factor (FF) of 0.53 under simulated solar illumination of AM 1.5 G (100 mW cm(-2) ). In addition, P2:PC71 BM blend-based solar cells exhibit a PCE of 1.42% with a comparable Voc of 0.89 V, a Jsc of 3.0 mA cm(-2) , and an FF of 0.53. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photo-processing P3HT conjugated polymers, in solution: A new route towards ordered polymeric structures.

NASA Astrophysics Data System (ADS)

Barbosa Neto, Newton; Dutra, Marcia; Araujo, Paulo; Sampaio, Renato

Solution aggregated thin films of conjugated polymers have demonstrated to be promising materials for many applications, e.g., solar cells and field-effect transistors. There are many standard methods to generate aggregates in polymeric solution, which includes poor solvent addiction and solution temperature manipulation. Here, we demonstrate a new approach to induce aggregate formation on solution of P3HT polymer. Under light excitation with 355 nm or 532 nm pulsed laser the polymer exhibit significant changes on its UV-Vis spectrum which are most known in the literature as the formation of H-J aggregates and additional new bands associated with polaron formation. Such changes in the amorphous phase of the polymers are seen in specific conditions of solvent combinations. We show also the dependency on the excitation laser power which can be identified as a threshold to ignite the formation of the new structure. We are grateful to CNPq and CAPES for financial support.

Effects of Molecular Structure and Packing Order on the Stretchability of Semicrystalline Conjugated Poly(Tetrathienoacene-diketopyrrolopyrrole) Polymers

DOE PAGES

Lu, Chien; Lee, Wen-Ya; Gu, Xiaodan; ...

2016-12-23

The design of polymer semiconductors possessing high charge transport performance, coupled with good ductility, remains a challenge. Understanding the distribution and behavior of both crystalline domains and amorphous regions in conjugated polymer films, upon an applied stress, shall provide general guiding principles to design stretchable organic semiconductors. Structure–property relationships (especially in both side chain and backbone engineering) are investigated for a series of poly(tetrathienoacene-diketopyrrolopyrrole) polymers. It is observed that the fused thiophene diketopyrrolopyrrole-based polymer, when incorporated with branched side chains and an additional thiophene spacer in the backbone, exhibits improved mechanical endurance and, in addition, does not show crack propagationmore » until 40% strain. Furthermore, this polymer exhibits a hole mobility of 0.1 cm2 V -1 s -1 even at 100% strain or after recovered from strain, which reveals prominent continuity and viscoelasticity of the polymer thin film. In conclusion, it is also observed that the molecular packing orientations (either edge-on or face-on) significantly affect the mechanical compliance of the polymer films. The improved stretchability of the polymers is attributed to both the presence of soft amorphous regions and the intrinsic packing arrangement of its crystalline domains.« less

Effects of Molecular Structure and Packing Order on the Stretchability of Semicrystalline Conjugated Poly(Tetrathienoacene-diketopyrrolopyrrole) Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Chien; Lee, Wen-Ya; Gu, Xiaodan

The design of polymer semiconductors possessing high charge transport performance, coupled with good ductility, remains a challenge. Understanding the distribution and behavior of both crystalline domains and amorphous regions in conjugated polymer films, upon an applied stress, shall provide general guiding principles to design stretchable organic semiconductors. Structure–property relationships (especially in both side chain and backbone engineering) are investigated for a series of poly(tetrathienoacene-diketopyrrolopyrrole) polymers. It is observed that the fused thiophene diketopyrrolopyrrole-based polymer, when incorporated with branched side chains and an additional thiophene spacer in the backbone, exhibits improved mechanical endurance and, in addition, does not show crack propagationmore » until 40% strain. Furthermore, this polymer exhibits a hole mobility of 0.1 cm2 V -1 s -1 even at 100% strain or after recovered from strain, which reveals prominent continuity and viscoelasticity of the polymer thin film. In conclusion, it is also observed that the molecular packing orientations (either edge-on or face-on) significantly affect the mechanical compliance of the polymer films. The improved stretchability of the polymers is attributed to both the presence of soft amorphous regions and the intrinsic packing arrangement of its crystalline domains.« less

An Integrated Laboratory Approach toward the Preparation of Conductive Poly(phenylene vinylene) Polymers

ERIC Educational Resources Information Center

Knoerzer, Timm A.; Balaich, Gary J.; Miller, Hannah A.; Iacono, Scott T.

2014-01-01

Poly(phenylene vinylene) (PPV) represents an important class of conjugated, conducting polymers that have been readily exploited in the preparation of organic electronic materials. In this experiment, students prepare a PPV polymer via a facile multistep synthetic sequence with robust spectroscopic evaluation of synthetic intermediates and the…

Thiazoloisoindigo: a Building Block that Merges the Merits of Thienoisoindigo and Diazaisoindigo for Conjugated Polymers.

PubMed

Wan, Xiaobo; Li, Chenchen; Wang, Xiao; Hio-Ieng, Un; Peng, Jiawei; Lan, Zhenggang; Cai, Mian; Pei, Jian; Wang, Jieyu

2018-04-24

Thiazoloisoindigo, a novel structural variation of isoindigo, is for the first time utilized to synthesize conjugated polymers. Polymer based on thiazoloisoindigo merges the advantages of the one based on thienoisoindigo and diazaisoindigo: It not only exhibits a greatly red shifted UV-vis absorption to the near-infrared region due to its strong tendency to form quinoidal structures, similar to that based on thienoisoindigo, but also shows excellent ambipolar mobility (hole 3.93 and electron 1.07 cm2 V-1 s-1, respectively) in organic field-effect transistors (OFETs), superior than that based on diazaisoindigo, showing the strong electron-withdrawing capability of thiazoloisoindigo. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Color Changes Mark Polymer Reactions.

ERIC Educational Resources Information Center

Krieger, James H.

1980-01-01

Describes how polydiacetylenes can be used as educational aids. These polymers have conjugated backbones, which cause changes in color when the polydiacetylenes undergo various chemical and physical processes. Diagrams summarize all chemical reactions and their associated color changes. (CS)

Influence of UV irradiation on hydroxypropyl methylcellulose polymer films

NASA Astrophysics Data System (ADS)

Rao, B. Lakshmeesha; Shivananda, C. S.; Shetty, G. Rajesha; Harish, K. V.; Madhukumar, R.; Sangappa, Y.

2018-05-01

Hydroxypropyl Methylcellulose (HPMC) biopolymer films were prepared by solution casting technique and effects of UV irradiation on the structural and optical properties of the polymer films were analysed using X-ray Diffraction and UV-Visible studies. From XRD data, the microcrystalline parameters (crystallite size (LXRD) and crystallinity (Xc)) were calculated and found to be decreasing with UV irradiation due to photo-degradation process. From the UV-Vis absorption data, the optical bandgap (Eg), average numbers of carbon atoms per conjugation length (N) of the polymer chain and the refractive index (n) at 550 nm (average wavelength of visible light) of virgin and UV irradiated HPMC films were calculated. With increase in UV exposure time, the optical bandgap energy (Eg) increases, and hence average number of carbon atoms per conjugation length (N) decreases, supports the photo-degradation of HPMC polymer films. The refractive index of the HPMC films decreases after UV irradiation, due to photo-degradation induced chain rearrangements.

EGF Functionalized Polymer-Coated Gold Nanoparticles Promote EGF Photostability and EGFR Internalization for Photothermal Therapy

PubMed Central

Silva, Catarina Oliveira; Petersen, Steffen B.; Reis, Catarina Pinto; Rijo, Patrícia; Molpeceres, Jesús; Fernandes, Ana Sofia; Gonçalves, Odete; Gomes, Andreia C.; Correia, Isabel; Vorum, Henrik; Neves-Petersen, Maria Teresa

2016-01-01

The application of functionalized nanocarriers on photothermal therapy for cancer ablation has wide interest. The success of this application depends on the therapeutic efficiency and biocompatibility of the system, but also on the stability and biorecognition of the conjugated protein. This study aims at investigating the hypothesis that EGF functionalized polymer-coated gold nanoparticles promote EGF photostability and EGFR internalization, making these conjugated particles suitable for photothermal therapy. The conjugated gold nanoparticles (100–200 nm) showed a plasmon absorption band located within the near-infrared range (650–900 nm), optimal for photothermal therapy applications. The effects of temperature, of polymer-coated gold nanoparticles and of UVB light (295nm) on the fluorescence properties of EGF have been investigated with steady-state and time-resolved fluorescence spectroscopy. The fluorescence properties of EGF, including the formation of Trp and Tyr photoproducts, is modulated by temperature and by the intensity of the excitation light. The presence of polymeric-coated gold nanoparticles reduced or even avoided the formation of Trp and Tyr photoproducts when EGF is exposed to UVB light, protecting this way the structure and function of EGF. Cytotoxicity studies of conjugated nanoparticles carried out in normal-like human keratinocytes showed small, concentration dependent decreases in cell viability (0–25%). Moreover, conjugated nanoparticles could activate and induce the internalization of overexpressed Epidermal Growth Factor Receptor in human lung carcinoma cells. In conclusion, the gold nanoparticles conjugated with Epidermal Growth Factor and coated with biopolymers developed in this work, show a potential application for near infrared photothermal therapy, which may efficiently destroy solid tumours, reducing the damage of the healthy tissue. PMID:27788212

Fluorinated benzothiadiazole-based conjugated polymers for high-performance polymer solar cells without any processing additives or post-treatments.

PubMed

Wang, Ning; Chen, Zheng; Wei, Wei; Jiang, Zhenhua

2013-11-13

Thanks to their many favorable advantages, polymer solar cells exhibit great potential for next-generation clean energy sources. Herein, we have successfully designed and synthesized a series of new fluorinated benzothiadiazole-based conjugated copolymers PBDT(TEH)-DT(H)BTff (P1), PBDT(TEH)-DT(EH)BTff (P2), and PBDT(HDO)-DT(H)BTff (P3). The power conversion efficiencies of 4.46, 6.20, and 8.30% were achieved for P1-, P2-, and P3-based devices within ~100 nm thickness active layers under AM 1.5G illumination without any processing additives or post-treatments, respectively. The PCE of 8.30% for P3 is the highest value for the reported traditional single-junction polymer solar cells via a simple fabrication architecture without any additives or post-treatments. In addition, it is noteworthy that P3 also allows making high efficient polymer solar cells with high PCEs of 7.27 and 6.56% under the same condition for ~200 and ~300 nm thickness active layers, respectively. Excellent photoelectric properties and good solubility make polymer P3 become an alternative material for high-performance polymer solar cells.

The Curious Case of Fluorination of Conjugated Polymers for Solar Cells.

PubMed

Zhang, Qianqian; Kelly, Mary Allison; Bauer, Nicole; You, Wei

2017-09-19

Organic solar cells (OSCs) have been a rising star in the field of renewable energy since the introduction of the bulk heterojunction (BHJ) in 1992. Recent advances have pushed the efficiencies of OSCs to over 13%, an impressive accomplishment via collaborative efforts in rational materials design and synthesis, careful device engineering, and fundamental understanding of device physics. Throughout these endeavors, several design principles for the conjugated donor polymers used in such solar cells have emerged, including optimizing the conjugated backbone with judicious selection of building blocks, side-chain engineering, and substituents. Among all of the substituents, fluorine is probably the most popular one; improved device characteristics with fluorination have frequently been reported for a wide range of conjugated polymers, in particular, donor-acceptor (D-A)-type polymers. Herein we examine the effect of fluorination on the device performance of solar cells as a function of the position of fluorination (on the acceptor unit or on the donor unit), aiming to outline a clear understanding of the benefits of this curious substituent. As fluorination of the acceptor unit is the most adopted strategy for D-A polymers, we first discuss the effect of fluorination of the acceptor units, highlighting the five most widely utilized acceptor units. While improved device efficiency has been widely observed with fluorinated acceptor units, the underlying reasons vary from case to case and highly depend on the chemical structure of the polymer. Second, the effect of fluorination of the donor unit is addressed. Here we focus on four donor units that have been most studied with fluorination. While device-performance-enhancing effects by fluorination of the donor units have also been observed, it is less clear that fluorine will always benefit the efficiency of the OSC, as there are several cases where the efficiency drops, in particular with "over-fluorination", i.e., when too many fluorine substituents are incorporated. Finally, while this Account focuses on studies in which the polymer is paired with fullerene derivatives as the electron accepting materials, non-fullerene acceptors (NFAs) are quickly becoming key players in the field of OSCs. The effect of fluorination of the polymers on the device performance may be different when NFAs are used as the electron-accepting materials, which remains to be investigated. However, the design of fluorinated polymers may provide guidelines for the design of more efficient NFAs. Indeed, the current highest-performing OSC (∼13%) features fluorination on both the donor polymer and the non-fullerene acceptor.

Buta-1,3-diyne-Based π-Conjugated Polymers for Organic Transistors and Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckstein, Brian J.; Melkonyan, Ferdinand S.; Zhou, Nanjia

We report the synthesis and characterization of new alkyl-substituted 1,4-di(thiophen-2-yl)buta-1,3-diyne (R-DTB) donor building blocks, based on the -C≡C-C≡C- conjugative pathway, and their incorporation with thienyl-diketopyrrolopyrrole (R'-TDPP) acceptor units into π-conjugated PTDPP-DTB polymers (P1-P4). The solubility of the new polymers strongly depends on the DTB and DPP solubilizing (R and R', respectively) substituents. Thus, solution processable and high molecular weight PDPP-DTB polymers are achieved for P3 (R = n-C12H25, R' = 2- butyloctyl) and P4 (R = 2-ethylhexyl, R' = 2-butyloctyl). Systematic studies of P3 and P4 physicochemical properties are carried using optical spectroscopy, cyclic voltammetry, and thermal analysis, revealing characteristicmore » features of the dialkynyl motif. For the first time, optoelectronic devices (OFETs, OPVs) are fabricated with 1,3-butadiyne containing organic semiconductors. OFET hole mobilities and record OPV power conversion efficiencies for acetylenic organic materials approach 0.1 cm2/(V s) and 4%, respectively, which can be understood from detailed thin-film morphology and microstructural characterization using AFM, TEM, XRD, and GIWAXS methodologies. Importantly, DTB-based polymers (P3 and P4) exhibit, in addition to stabilization of frontier molecular orbitals and to -C≡C-C≡C- relief of steric torsions, discrete morphological pliability through thermal annealing and processing additives. The advantageous materials properties and preliminary device performance reported here demonstrate the promise of 1,3-butadiyne-based semiconducting polymers.« less

The synthesis, self-assembling, and biocompatibility of a novel O-carboxymethyl chitosan cholate decorated with glycyrrhetinic acid.

PubMed

Du, Hongliang; Yang, Xiaoye; Pang, Xin; Zhai, Guangxi

2014-10-13

O-carboxymethyl chitosan (OCMC) was firstly decorated with cholic acid (CA) to acquire an amphiphilic polymer under alkaline condition. Then glycyrrhetinic acid (GA) was conjugated to the polymer via a succinate linker and finally treated with NaCO3 solution to obtain new conjugates for potential liver targeted delivery. These conjugates formed uniform aggregates with low critical aggregation concentrations (0.028-0.079 mg/mL) in PBS. The average diameter of cholic acid modified carboxymethyl chitosan (CMCA) aggregates (110-257 nm) decreased with the increase of CA substitution degree and became slightly larger after GA modification. Negative zeta potential (-15 mV) of GA decorated CMCA (GA-CMCA) revealed that the formation of negatively charged shells and spherical morphology was observed under transmission electron microscopy. Furthermore, hemolysis test, in vitro cytotoxicity assay and cellular uptake study all demonstrated the safety and feasibility of these conjugates as a promising carrier for liver targeted drug delivery. Copyright © 2014 Elsevier Ltd. All rights reserved.

Recyclable Thermoresponsive Polymer-β-Glucosidase Conjugate with Intact Hydrolysis Activity.

PubMed

Mukherjee, Ishita; Sinha, Sushant K; Datta, Supratim; De, Priyadarsi

2018-06-11

β-Glucosidase (BG) catalyzes the hydrolysis of cellobiose to glucose and is a rate-limiting enzyme in the conversion of lignocellulosic biomass to sugars toward biofuels. Since the cost of enzyme is a major contributor to biofuel economics, we report the bioconjugation of a temperature-responsive polymer with the highly active thermophilic β-glucosidase (B8CYA8) from Halothermothrix orenii toward improving enzyme recyclability. The bioconjugate, with a lower critical solution temperature (LCST) of 33 °C withstands high temperatures up to 70 °C. Though the secondary structure of the enzyme in the conjugate is slightly distorted with a higher percentage of β-sheet like structure, the stability and specific activity of B8CYA8 in the conjugate remains unaltered up to 30 °C and retains more than 70% specific activity of the unmodified enzyme at 70 °C. The conjugate can be reused for β-glucosidic bond cleavage of cellobiose for at least four cycles without any significant loss in specific activity.

PEG conjugates in clinical development or use as anticancer agents: an overview.

PubMed

Pasut, Gianfranco; Veronese, Francesco M

2009-11-12

During the almost forty years of PEGylation, several antitumour agents, either proteins, peptides or low molecular weight drugs, have been considered for polymer conjugation but only few entered clinical phase studies. The results from the first clinical trials have shared and improved the knowledge on biodistribution, clearance, mechanism of action and stability of a polymer conjugate in vivo. This has helped to design conjugates with improved features. So far, most of the PEG conjugates comprise of a protein, which in the native form has serious shortcomings that limit the full exploitation of its therapeutic action. The main issues can be short in vivo half-life, instability towards degrading enzymes or immunogenicity. PEGylation proved to be effective in shielding sensitive sites at the protein surface, such as antigenic epitopes and enzymatic degradable sequences, as well as in prolonging the drug half-life by decreasing the kidney clearance. In this review PEG conjugates of proteins or low molecular weight drugs, in clinical development or use as anticancer agents, will be taken into consideration. In the case of PEG-protein derivatives the most represented are depleting enzymes, which act by degrading amino acids essential for cancer cells. Interestingly, PEGylated conjugates have been also considered as adjuvant therapy in many standard anticancer protocols, in this regard the case of PEG-G-CSF and PEG-interferons will be presented.

Developing new methods for the mono-end functionalization of living ring opening metathesis polymers.

PubMed

Kilbinger, Andreas F M

2012-01-01

In this article we present a review of our recent results in one area of research we are involved in. All research efforts in our group focus on functional polymers and new ways of gaining higher levels of control with regard to the placement of functional groups within these polymers. Here, the living ring opening metathesis polymerization (ROMP) will be reviewed for which end-functionalization methods had been rare until very recently. Polymers carrying particular functional groups only at the chain-ends are, however, very interesting for a variety of industrial and academic applications. Polymeric surfactants and polymer-protein conjugates are two examples for the former and polymer-β-sheet-peptide conjugates one example for the latter. The functionalization of macroscopic or nanoscopic surfaces often relies on mono-end functional polymers. Complex macromolecular architectures are often constructed from macromolecules carrying exactly one functional group at their chain- end. The ring opening metathesis polymerization is particularly interesting in this context as it is one of the most functional group tolerant polymerization methods known. Additionally, high molecular weight polymers are readily accessible with this technique, a feature that living radical polymerizations often struggle to achieve. Finding new ways of functionalizing the polymer chain-end of ROMP polymers has therefore been a task long overdue. Here, we present our contribution to this area of research.

Development of buccal drug delivery systems based on a thiolated polymer.

PubMed

Langoth, Nina; Kalbe, Jochen; Bernkop-Schnürch, Andreas

2003-02-18

The purpose of the present study was to investigate the benefit of thiolated polymers (thiomers) for the development of buccal drug delivery systems. L-Cysteine was thereby covalently attached to polycarbophil (PCP) mediated by a carbodiimide. The resulting conjugate displayed 140.5+/-8.4 microM thiol groups per gram polymer. Disintegration studies were carried out with tablets based on unmodified polymer and conjugated polymer, respectively. Due to the formation of disulfide bonds within the thiolated polymer, the stability of matrix-tablets based on this polymer was strongly improved. Additionally tensile studies were carried out, which were in good correlation with further results obtained by mucoadhesion studies, using the rotating cylinder method. These results showed that tablets based on thiolated PCP remained attached on freshly excised porcine mucosa 1.8 times longer than the corresponding control. Moreover, the enzyme inhibitory properties of polymers were evaluated as well. Thiolated PCP increased the stability of the synthetic substrate for aminopeptidase N-leu-p-nitroanilide (N-leu-pNA) and the model drug leucin-enkephalin (leu-enkephalin) against enzymatic degradation on buccal mucosa. Due to the use of thiolated polymers also a controlled drug release for leu-enkephalin was guaranteed over a time period for more than 24 h. Results of the present studies suggest that thiolated polymers represent a very useful tool for buccal delivery of peptide drugs.

Guided in Situ Polymerization of MEH-PPV in Mesoporous Titania Photoanodes.

PubMed

Minar, Norma K; Docampo, Pablo; Fattakhova-Rohlfing, Dina; Bein, Thomas

2015-05-20

Incorporation of conjugated polymers into porous metal oxide networks is a challenging task, which is being pursued via many different approaches. We have developed the guided in situ polymerization of poly(2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) in porous titania films by means of surface functionalization. The controlled polymerization via the Gilch route was induced by an alkoxide base and by increasing the temperature. The selected and specially designed surface-functionalizing linker molecules mimic the monomer or its activated form, respectively. In this way, we drastically enhanced the amount of MEH-PPV incorporated into the porous titania phase compared to nonfunctionalized samples by a factor of 6. Additionally, photovoltaic measurements were performed. The devices show shunting or series resistance limitations, depending on the surface functionalization prior to in situ polymerization of MEH-PPV. We suggest that the reason for this behavior can be found in the orientation of the grown polymer chains with respect to the titania surface. Therefore, the geometry of the anchoring via the linker molecules is relevant for exploiting the full electronic potential of the conjugated polymer in the resulting hybrid composite. This observation will help to design future synthesis methods for new hybrid materials from conjugated polymers and n-type semiconductors to take full advantage of favorable electronic interactions between the two phases.

Tuning the thermal conductivity of solar cell polymers through side chain engineering.

PubMed

Guo, Zhi; Lee, Doyun; Liu, Yi; Sun, Fangyuan; Sliwinski, Anna; Gao, Haifeng; Burns, Peter C; Huang, Libai; Luo, Tengfei

2014-05-07

Thermal transport is critical to the performance and reliability of polymer-based energy devices, ranging from solar cells to thermoelectrics. This work shows that the thermal conductivity of a low band gap conjugated polymer, poly(4,8-bis-alkyloxybenzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-(alkylthieno[3,4-b]thiophene-2-carboxylate)-2,6-diyl) (PBDTTT), for photovoltaic applications can be actively tuned through side chain engineering. Compared to the original polymer modified with short branched side chains, the engineered polymer using all linear and long side chains shows a 160% increase in thermal conductivity. The thermal conductivity of the polymer exhibits a good correlation with the side chain lengths as well as the crystallinity of the polymer characterized using small-angle X-ray scattering (SAXS) experiments. Molecular dynamics simulations and atomic force microscopy are used to further probe the molecular level local order of different polymers. It is found that the linear side chain modified polymer can facilitate the formation of more ordered structures, as compared to the branched side chain modified ones. The effective medium theory modelling also reveals that the long linear side chain enables a larger heat carrier propagation length and the crystalline phase in the bulk polymer increases the overall thermal conductivity. It is concluded that both the length of the side chains and the induced polymer crystallization are important for thermal transport. These results offer important guidance for actively tuning the thermal conductivity of conjugated polymers through molecular level design.

Molecular Design and Device Application of Radical Polymers for Improved Charge Extraction in Organic Photovoltaic Cells

DTIC Science & Technology

2015-07-29

a. “Engineering Optoelectronically-active Macromolecules for Polymer-based Photovoltaic and Thermoelectric Devices,” Boudouris, B. W. Current...Presentation. Oral Presentation. “Non-conjugated Radical Polymers as an Emerging Class of Transparent Conductors in Organic Photovoltaic and Thermoelectric ...for Polymer-based Photovoltaic and Thermoelectric Devices,” Boudouris, B. W. Current Opinion in Chemical Engineering 2013, 2, 294-301. 2. “Controlled

Planar-Processed Polymer Transistors.

PubMed

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.

Remarkable enhancement of charge carrier mobility of conjugated polymer field-effect transistors upon incorporating an ionic additive

PubMed Central

Luo, Hewei; Yu, Chenmin; Liu, Zitong; Zhang, Guanxin; Geng, Hua; Yi, Yuanping; Broch, Katharina; Hu, Yuanyuan; Sadhanala, Aditya; Jiang, Lang; Qi, Penglin; Cai, Zhengxu; Sirringhaus, Henning; Zhang, Deqing

2016-01-01

Organic semiconductors with high charge carrier mobilities are crucial for flexible electronic applications. Apart from designing new conjugated frameworks, different strategies have been explored to increase charge carrier mobilities. We report a new and simple approach to enhancing the charge carrier mobility of DPP-thieno[3,2-b]thiophene–conjugated polymer by incorporating an ionic additive, tetramethylammonium iodide, without extra treatments into the polymer. The resulting thin films exhibit a very high hole mobility, which is higher by a factor of 24 than that of thin films without the ionic additive under the same conditions. On the basis of spectroscopic grazing incidence wide-angle x-ray scattering and atomic force microscopy studies as well as theoretical calculations, the remarkable enhancement of charge mobility upon addition of tetramethylammonium iodide is attributed primarily to an inhibition of the torsion of the alkyl side chains by the presence of the ionic species, facilitating a more ordered lamellar packing of the alkyl side chains and interchain π-π interactions. PMID:27386541

Enhancement of the electromechanical transduction properties of a silicone elastomer by blending with a conjugated polymer

NASA Astrophysics Data System (ADS)

Carpi, F.; Gallone, G.; Galantini, F.; De Rossi, D.

2008-03-01

The need for high driving electric fields currently limits the diffusion of dielectric elastomer actuation in some areas of potential application, especially in the case of biomedical disciplines. A reduction of the driving fields may be achieved with new elastomers offering intrinsically superior electromechanical properties. So far, most of attempts in this direction have been focused on composites between elastomer matrixes and high-permittivity ceramic fillers, yielding to limited results. In this work, the electromechanical response of a silicone rubber (poly-dimethyl-siloxane) was improved by blending, rather than loading, the elastomer with a highly polarizable conjugated polymer (undoped poly-hexyl-thiophene). Very low percentages (1-6 wt%) of poly-hexyl-thiophene yielded both an increase of the dielectric permittivity and an unexpected reduction of the tensile elastic modulus. Both these factors contributed to a remarkable increase of the electromechanical response, which reached a maximum at 1 wt% content of conjugated polymer. This approach may lead to the development of new types of improved dielectric elastomers for actuation.

Temporal switching of homo-FRET pathways in single-chromophore dimer models of π-conjugated polymers.

PubMed

Stangl, Thomas; Bange, Sebastian; Schmitz, Daniela; Würsch, Dominik; Höger, Sigurd; Vogelsang, Jan; Lupton, John M

2013-01-09

A set of π-conjugated oligomer dimers templated in molecular scaffolds is presented as a model system for studying the interactions between chromophores in conjugated polymers (CPs). Single-molecule spectroscopy was used to reveal energy transfer dynamics between two oligomers in either a parallel or oblique-angle geometry. In particular, the conformation of single molecules embedded in a host matrix was investigated via polarized excitation and emission fluorescence microscopy in combination with fluorescence correlation spectroscopy. While the intramolecular interchromophore conformation was found to have no impact on the fluorescence quantum yield, lifetime, or photon statistics (antibunching), the long-term nonequilibrium dynamics of energy transfer within these bichromophoric systems was accessible by studying the linear dichroism in emission at the single-molecule level, which revealed reversible switching of the emission between the two oligomers. In bulk polymer films, interchromophore coupling promotes the migration of excitation energy to quenching sites. Realizing the presence and dynamics of such interactions is crucial for understanding limitations on the quantum efficiency of larger CP materials.

RIR-MAPLE deposition of conjugated polymers and hybrid nanocomposites for application to optoelectronic devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stiff-Roberts, Adrienne D.; Pate, Ryan; McCormick, Ryan

2012-07-30

Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) is a variation of pulsed laser deposition that is useful for organic-based thin films because it reduces material degradation by selective absorption of infrared radiation in the host matrix. A unique emulsion-based RIR-MAPLE approach has been developed that reduces substrate exposure to solvents and provides controlled and repeatable organic thin film deposition. In order to establish emulsion-based RIR-MAPLE as a preferred deposition technique for conjugated polymer or hybrid nanocomposite optoelectronic devices, studies have been conducted to demonstrate the value added by the approach in comparison to traditional solution-based deposition techniques, and this workmore » will be reviewed. The control of hybrid nanocomposite thin film deposition, and the photoconductivity in such materials deposited using emulsion-based RIR-MAPLE, will also be reviewed. The overall result of these studies is the demonstration of emulsion-based RIR-MAPLE as a viable option for the fabrication of conjugated polymer and hybrid nanocomposite optoelectronic devices that could yield improved device performance.« less

Thiolated citrus low-methoxyl pectin: Synthesis, characterization and rheological and oxidation-responsive gelling properties.

PubMed

Chen, Jinfeng; Ye, Fayin; Zhou, Yun; Zhao, Guohua

2018-02-01

In the present study, citrus low-methoxyl pectin was modified by conjugating cysteine via amide bonds, and the resultant polymer (CYS-PEC) was characterized. CYS-PEC conjugates with thiol contents varying from 77.8μmol/g to 296μmol/g were synthesized, and the successful conjugation was evidenced by elemental, and FT-IR analyses. The sulfur in CYS-PEC is predominately in the thiol form, with a minor fraction forming disulfide bonds (∼15%), which occur when thiol/disulfide interchange interrupts the intended thiolation. Both native and modified pectin dispersions exhibited strong pseudoplastic properties, and the frequency sweeps revealed them to be dispersions containing microgel particles. Dynamic viscoelastic analysis was used to determine the oxidation-response gelling capacities of polymer dispersions containing H 2 O 2 , especially those that are highly thiolated and have cross-linked gel properties. For oxidation-induced CYS-PEC gels, their gelation time, hardness, viscosity and elastic moduli and swelling-disintegration ratio are dependent on the thiol group content, H 2 O 2 concentration and polymer concentration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fluorene-Based Conjugated Microporous Polymers: Preparation and Chemical Sensing Application.

PubMed

Zhang, Qiujing; Yu, Sen; Wang, Qian; Xiao, Qin; Yue, Yong; Ren, Shijie

2017-12-01

Conjugated microporous polymers (CMPs) with strong fluorescence are great candidates for optoelectronic applications such as photocatalysis and chemical sensing. A series of novel fluorene-based conjugated microporous polymers (FCMPs) with different electronic structures are prepared by Yamamoto coupling reactions using rationally designed monomers. The FCMPs show a high degree of microporosity, decent specific surface areas, and variable fluorescence. FCMP3, which possesses a triazine knot in the network, exhibits the highest specific surface area of 489 m 2 g -1 , the largest pore volume of 0.30 cm 3 g -1 , and the highest solid-state photoluminescence quantum yield of 11.46%. Chemical sensing performance of FCMPs is studied using a range of nitroaromatic compounds as the analytes. Among the FCMPs, FCMP3 exhibits the highest Stern-Volmer constants of 2541, 4708, and 5241 m -1 for the detection of nitrobenzene, 4-nitrotoluene, 2,4-dinitrotoluene, respectively, which are comparable to the detecting efficiency of the state-of-the-art CMP-based sensing agents. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct heteroarylation polymerization: guidelines for defect-free conjugated polymers.

PubMed

Bura, Thomas; Beaupré, Serge; Légaré, Marc-André; Quinn, Jesse; Rochette, Etienne; Blaskovits, J Terence; Fontaine, Frédéric-Georges; Pron, Agnieszka; Li, Yuning; Leclerc, Mario

2017-05-01

Direct (hetero)arylation polymerization (DHAP) has emerged as a valuable and atom-economical alternative to traditional cross-coupling methods for the synthesis of low-cost and efficient conjugated polymers for organic electronics. However, when applied to the synthesis of certain (hetero)arene-based materials, a lack of C-H bond selectivity has been observed. To prevent such undesirable side-reactions, we report the design and synthesis of new, bulky, phosphine-based ligands that significantly enhance selectivity of the DHAP process for both halogenated and non-halogenated electron-rich and electron-deficient thiophene-based comonomers. To better understand the selectivity issues, density functional theory (DFT) calculations have been performed on various halogenated and non-halogenated electron-rich and electron-deficient thiophene-based comonomers. Calculations showed that the presence of bromine atoms decreases the energy of activation ( E a ) of the adjacent C-H bonds, allowing undesirable β-defects for some brominated aromatic units. Both calculations and the new ligands should lead to the rational design of monomers and methods for the preparation of defect-free conjugated polymers from DHAP.

Refreshing Rubbers as Customized Photothermal Conversion Materials through Post-Darkening Modeling Production.

PubMed

Li, Ruiting; Wang, Zhen; Han, Peng; He, Yonglin; Zhang, Xiaohong; Wang, Yapei

2017-12-19

Organic conjugated polymers with low energy bandgaps are emerging as a particular class of near-infrared (NIR) photothermal conversion materials. However, these polymers routinely possess high phase transition temperatures due to the rigid skeleton and strong intermolecular interactions. Conjugated polymers can rarely be thermally processed at low temperature, especially below 100 °C. This work formulates a concept of post-darkening modeling production (p-DMP) by which the thermoplastic non-conjugated trans-polyisoprene (TPI) is refreshed into a photothermal conversion material with high light use efficiency. Two steps, including the customizable shaping at low temperature and iodine vapor-tailored "darkening", ensure the ease of preparing photothermal conversion devices with desirable topologies. A few characterizations, with the combination of density functional theory (DFT) calculations, provide reasonable explanations for understanding the "darkening" process of TPI in iodine atmosphere. In particular, the p-DMP is successfully extended to three-dimension (3D) printing, opening an avenue to fabricate personalized photothermal products, for example, a sunlight-directed physiotherapy device for healthcare of articular tissues. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Studies of Luminescence Performance on Carbazole Donor and Quinoline Acceptor Based Conjugated Polymer.

PubMed

Upadhyay, Anjali; S, Karpagam

2016-03-01

We report on the synthesis of conjugated polymer (CV-QP) containing carbazole (donor) and quinoline (acceptor) using Wittig methodology. The structural, optical and thermal properties of the polymer were investigated by FT-IR, NMR, GPC, UV, PL, cyclic voltammetry, atomic force microscopy (AFM) and thermogravimetric analysis (TGA). The polymer exhibits thermal stability upto 200 °C and shows good solubility in common organic solvents. The polymer has optical absorption band in a thin film at 360 nm and emission band formed at 473 nm. The optical energy band gap was found to be 2.69 eV as calculated from the onset absorption edge. Fluorescence quenching of the polymer CV-QP was found by using DMA (electron donor) and DMTP (electron acceptor). AFM image indicated that triangular shaped particles were observed and the particle size was found as 1.1 μm. The electrochemical studies of CV-QP reveal that, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the CV-QP are 6.35 and 3.70 eV, which indicated that the polymers are expected to provide charge transporting properties for the development of polymer light-emitting diodes (PLEDs).

Symmetry Breaking in Side Chains Leading to Mixed Orientations and Improved Charge Transport in Isoindigo- alt -Bithiophene Based Polymer Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xue, Guobiao; Zhao, Xikang; Qu, Ge

The selection of side chains is important in design of conjugated polymers. It not only affects their intrinsic physical properties, but also has an impact on thin film morphologies. Recent reports suggested that a face-on/edge-on bimodal orientation observed in polymer thin films may be responsible for a three-dimensional (3D) charge transport and leads to dramatically improved mobility in donor–acceptor based conjugated polymers. To achieve a bimodal orientation in thin films has been seldom explored from the aspect of molecular design. Here, we demonstrate a design strategy involving the use of asymmetric side chains that enables an isoindigo-based polymer to adoptmore » a distinct bimodal orientation, confirmed by the grazing incidence X-ray diffraction. As a result, the polymer presents an average high mobility of 3.8 ± 0.7 cm2 V–1 s–1 with a maximum value of 5.1 cm2 V–1 s–1, in comparison with 0.47 and 0.51 cm2 V–1 s–1 obtained from the two reference polymers. This study exemplifies a new strategy to develop the next generation polymers through understanding the property-structure relationship.« less

76 FR 6335 - Sodium and Potassium Salts of N-alkyl (C8

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-04

...): Solvents such as alcohols and hydrocarbons; surfactants such as polyoxyethylene polymers and fatty acids... metabolites are not systemically toxic and would be rapidly conjugated and excreted. The SSNA surfactants (mono and di-sodium propionates) may be conjugated and excreted directly. Alternatively, the tertiary...

Spin-correlated doublet pairs as intermediate states in charge separation processes

NASA Astrophysics Data System (ADS)

Kraffert, Felix; Behrends, Jan

2017-10-01

Spin-correlated charge-carrier pairs play a crucial role as intermediate states in charge separation both in natural photosynthesis as well as in solar cells. Using transient electron paramagnetic resonance (trEPR) spectroscopy in combination with spectral simulations, we study spin-correlated polaron pairs in polymer:fullerene blends as organic solar cells materials. The semi-analytical simulations presented here are based on the well-established theoretical description of spin-correlated radical pairs in biological systems, however, explicitly considering the disordered nature of polymer:fullerene blends. The large degree of disorder leads to the fact that many different relative orientations between both polarons forming the spin-correlated pairs have to be taken into account. This has important implications for the spectra, which differ significantly from those of spin-correlated radical pairs with a fixed relative orientation. We systematically study the influence of exchange and dipolar couplings on the trEPR spectra and compare the simulation results to measured X- and Q-band trEPR spectra. Our results demonstrate that assuming dipolar couplings alone does not allow us to reproduce the experimental spectra. Due to the rather delocalised nature of polarons in conjugated organic semiconductors, a significant isotropic exchange coupling needs to be included to achieve good agreement between experiments and simulations.

Metallated porphyrin-doped conjugated polymer nanoparticles for efficient photodynamic therapy of brain and colorectal tumor cells.

PubMed

Ibarra, Luis Exequiel; Porcal, Gabriela Valeria; Macor, Lorena Paola; Ponzio, Rodrigo Andrés; Spada, Ramiro Martin; Lorente, Carolina; Chesta, Carlos Alberto; Rivarola, Viviana Alicia; Palacios, Rodrigo Emiliano

2018-03-01

 Assess biocompatibility, uptake and photodynamic therapy (PDT) mechanism of metallated porphyrin doped conjugated polymer nanoparticles (CPNs) in human brain and colorectal tumor cells and macrophages. CPNs were developed employing 9,9-dioctylfluorene-alt-benzothiadiazole, an amphiphilic polymer (PS-PEG-COOH),  and platinum octaethylporphyrin. T98G, SW480 and RAW 264.7 cell lines were exposed to CPNs to assess uptake and intracellular localization. Additionally, a PDT protocol using CPNs was employed for the in vitro killing of cancer and macrophage cell lines. CPNs were well incorporated into glioblastoma and macrophage cells with localization in lysosomes. SW480 cells were less efficient incorporating CPNs with localization in the plasma membrane. In all cell lines PDT treatment was efficient inducing oxidative stress that triggered apoptosis.

Synthesis and Photovoltaic Properties of a Copolymer based on thieno [2, 3-f] benzofuran and thienopyrroledione

NASA Astrophysics Data System (ADS)

Gao, Yueyue; Yang, Yulin; Zhang, Yong

2017-12-01

A novel donor-acceptor type conjugated polymer PTBFTPD based on two-dimensional (2D) conjugated alkylthienyl substituted thieno[2,3-f]benzofuran (TBF) and thienopyrroledione (TPD) unit, was synthesized and applied as donor material for bulk heterojunction solar cells. The novol polymer possesses a narrow bandgap of 1.83 eV, a deep HOMO energy level (-5.64 eV) and a closer π-π stacking. After conventional devices were fabricated using PTBFTPD as donor blending with PC70BM as acceptor, a power conversion efficiency (PCE) of 4.33% with a high open circuit voltage (Voc) of 1.09 V was obtained. The result indicates the promising potential of thieno [2, 3-f] benzofuran unit for high efficient polymer solar cells with a high voltage.

Tuning the properties of conjugated polyelectrolytes and application in a biosensor platform

DOEpatents

Chen, Liaohai

2004-05-18

The present invention provides a method of detecting a biological agent including contacting a sample with a sensor including a polymer system capable of having an alterable measurable property from the group of luminescence, anisotropy, redox potential and uv/vis absorption, the polymer system including an ionic conjugated polymer and an electronically inert polyelectrolyte having a biological agent recognition element bound thereto, the electronically inert polyelectrolyte adapted for undergoing a conformational structural change upon exposure to a biological agent having affinity for binding to the recognition element bound to the electronically inert polyelectrolyte, and, detecting the detectable change in the alterable measurable property. A chemical moiety being the reaction product of (i) a polyelectrolyte monomer and (ii) a biological agent recognition element-substituted polyelectrolyte monomer is also provided.

Inkjet printing of conjugated polymer precursors on paper substrates for colorimetric sensing and flexible electrothermochromic display.

PubMed

Yoon, Bora; Ham, Dae-Young; Yarimaga, Oktay; An, Hyosung; Lee, Chan Woo; Kim, Jong-Man

2011-12-08

Inkjet-printable aqueous suspensions of conjugated polymer precursors are developed for fabrication of patterned color images on paper substrates. Printing of a diacetylene (DA)-surfactant composite ink on unmodified paper and photopaper, as well as on a banknote, enables generation of latent images that are transformed to blue-colored polydiacetylene (PDA) structures by UV irradiation. Both irreversible and reversible thermochromism with the PDA printed images are demonstrated and applied to flexible and disposable sensors and to displays. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conjugated polymer nanoparticles-based fluorescent biosensor for ultrasensitive detection of hydroquinone.

PubMed

Liu, Yuan; Wang, Yu-Min; Zhu, Wu-Yang; Zhang, Chong-Hua; Tang, Hao; Jiang, Jian-Hui

2018-07-05

This work describes a simple and sensitive fluorescent method for detection of hydroquinone utilizing conjugated polymer nanoparticles (CPNs). The CPNs serve both as a catalyst to accelerate the conversion of hydroquinone to benzoquinone and a fluorescent probe. In the presence of hydroquinone, the fluorescence of CPNs can be effectively quenched by benzoquinone. The detection limit of hydroquinone was down to 5 nM and excellent selectivity toward possible interferences was obtained. This method was successfully applied for hydroquinone detection in lake water and satisfactory results were achieved. Copyright © 2018 Elsevier B.V. All rights reserved.

Interplay of localized pyrene chromophores and π-conjugation in novel poly(2,7-pyrene) ladder polymers

NASA Astrophysics Data System (ADS)

Rudnick, Alexander; Kass, Kim-Julia; Preis, Eduard; Scherf, Ullrich; Bässler, Heinz; Köhler, Anna

2017-05-01

We present a detailed spectroscopic study, along with the synthesis, of conjugated, ladder-type 2,7-linked poly(pyrene)s. We observe a delocalization of the first singlet excited state along the polymer backbone, i.e., across the 2,7 linkage in the pyrene moiety, in contrast to earlier studies on conjugated 2,7-linked poly(pyrene)s without ladder structure. The electronic signature of the pyrene unit is, however, manifested in an increased lifetime and reduced oscillator strength as well as a modified vibronic progression in absorption of the singlet state compared to a ladder-type poly(para-phenylene) (MeLPPP). Furthermore, the reduced oscillator strength and increased lifetime slow down Förster-type energy transfer in films, where this transfer occurs to sites with increasing inter-chain coupling of H-type nature.

Prolonged local retention of subcutaneously injected polymers monitored by noninvasive SPECT imaging.

PubMed

Kojima, Chie; Niki, Yuichiro; Ogawa, Mikako; Magata, Yasuhiro

2014-12-10

Polymers are widely applied to drug delivery systems because polymers are generally excreted from the body more slowly than small molecules. Subcutaneous injection is one plausible means of administration. In this study, the in vivo behaviors of subcutaneously injected polymers, linear poly(glutamic acid) (Poly-Glu), acetylated dendrimer (Ac-den) and collagen peptide-conjugated dendrimer (CP-den), were investigated. Single photon emission computed tomography (SPECT) imaging was used to noninvasively monitor the in vivo behaviors. Diethylenetriaminepentaacetic acid (DTPA) was conjugated to these polymers, which were labeled with radioactive (111)In. These (111)In-DTPA-bearing polymers (Poly-Glu-DTPA, Ac-den-DTPA and CP-den-DTPA) and unconjugated DTPA were subcutaneously injected into tumor-bearing mice, which were subjected to SPECT imaging. These (111)In-DTPA-bearing polymers were largely retained at the injection site for at least 1 day, whereas the unconjugated DTPA was rapidly cleared from the whole body through excretion. Poly-Glu-DTPA and Ac-den-DTPA were partly accumulated in the kidney (and the liver), but the CP-den-DTPA was not. However, these (111)In-DTPA-bearing polymers were accumulated in the liver and the kidney following intravenous administration. These results indicate that the subcutaneously injected polymers did not largely gain substantial access to the systemic circulation, which is useful for a depot of drug around the injection site. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthetic polymer nanoparticles conjugated with FimH(A) from E. coli pili to emulate the bacterial mode of epithelial internalization.

PubMed

Lin, Lily Yun; Tiemann, Kristin M; Li, Yali; Pinkner, Jerome S; Walker, Jennifer N; Hultgren, Scott J; Hunstad, David A; Wooley, Karen L

2012-03-07

Amphiphilic block copolymer nanoparticles are conjugated with uropathogenic Escherichia coli type 1 pilus adhesin FimH(A) through amidation chemistry to enable bladder epithelial cell binding and internalization of the nanoparticles in vitro. © 2012 American Chemical Society

Soluble polymer conjugates for drug delivery.

PubMed

Minko, Tamara

2005-01-01

The use of water-soluble polymeric conjugates as drug carriers offers several possible advantages. These advantages include: (1) improved drug pharmacokinetics; (2) decreased toxicity to healthy organs; (3) possible facilitation of accumulation and preferential uptake by targeted cells; (4) programmed profile of drug release. In this review, we will consider the main types of useful polymeric conjugates and their role and effectiveness as carriers in drug delivery systems.: © 2005 Elsevier Ltd . All rights reserved.

Enhancement in fluorescence quantum yield of MEH-PPV:BT blends for polymer light emitting diode applications

NASA Astrophysics Data System (ADS)

Nimith, K. M.; Satyanarayan, M. N.; Umesh, G.

2018-06-01

We have investigated the effect of blending electron deficient heterocycle Benzothiadiazole (BT) on the photo-physical properties of conjugated polymer Poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). Quantum yield (QY) value has been found to increase from 37% for pure MEH-PPV to 45% for an optimum MEH-PPV:BT blend ratio of 1:3. This can be attributed to the efficient energy transfer from the wide bandgap BT (host) to the small bandgap MEH-PPV (guest). The FTIR spectrum of MEH-PPV:BT blended thin film indicates suppression of aromatic C-H out-of-plane and in-plane bending, suggesting planarization of the conjugated polymer chains and, hence, leading to increase in the conjugation length. The increase in conjugation length is also evident from the red-shifted PL spectra of MEH-PPV:BT blended films. Single layer MEH-PPV:BT device shows lower turn-on voltage than single layer MEH-PPV alone device. Further, the effect of electrical conductivity of PEDOT:PSS on the current-voltage characteristics is investigated in the PLED devices with MEH-PPV:BT blend as the active layer. PEDOT:PSS with higher conductivity as HIL reduces the turn on voltage from 4.5 V to 3.9 V and enhances the current density and optical output in the device.

Undergraduate HBCU Student Summer Training Program for Developing Nanomedicines to Treat Prostate Cancers

DTIC Science & Technology

2016-08-01

and interpret generated MS data. She also got familiarized with synthesis of HPMA polymer and conjugation of targeted peptide to the polymer . During...techniques (Ciera), polymer synthesis and nanomedicine development (Starr and Andrea), the effect of drug treatment on prostate cancer cells (My’Chelle...career in the field of prostate cancer. W81XWH-15-1-0202 15. SUBJECT TERMS Prostate cancer, co- polymer , anti-androgen, peptide-based targeting

Dual function conducting polymer diodes

DOEpatents

Heeger, Alan J.; Yu, Gang

1996-01-01

Dual function diodes based on conjugated organic polymer active layers are disclosed. When positively biased the diodes function as light emitters. When negatively biased they are highly efficient photodiodes. Methods of preparation and use of these diodes in displays and input/output devices are also disclosed.

Magnetism in Pristine Pi-conjugated Polymers

DTIC Science & Technology

2014-09-07

highly regioregular poly(3-alkylthiophene)s and subsequently a ferromagnetic hysteretic behavior at low temperature (< 20K) in these polymers...and subsequently a ferromagnetic hysteretic behavior at low temperature (T < 20k) in these polymers. Concomitantly nanoscopic doughnut structures...the reproducibility, of this very new magneto-optic material . Ferromagnetism in polythiophenes A   first   and   very   important

Novel Polymers for High Efficiency Renewable and Portable Power Applications

DTIC Science & Technology

2015-07-30

photoelectric, thermoelectric , energy conversions, charge transfer, energy transfer, photoluminescence (PL). REPORT DOCUMENTATION PAGE 11. SPONSOR...of polymer/dye interface of photo generated excitons in the covalent system resulting in more efficient exciton dissociations. 4) For thermoelectric ...studies, it appears the thermoelectric charge carrier generations of the four conjugated polymers doped with iodine at room temperature are in the

Intrinsically stretchable and healable semiconducting polymer for organic transistors

DOE PAGES

Oh, Jin Young; Rondeau-Gagné, Simon; Chiu, Yu-Cheng; ...

2016-11-16

Developing a molecular design paradigm for conjugated polymers applicable to intrinsically stretchable semiconductors is crucial toward the next generation of wearable electronics. Current molecular design rules for high charge carrier mobility semiconducting polymers are unable to render the fabricated devices simultaneously stretchable and mechanically robust. Here in this paper, we present a new design concept to address the above challenge, while maintaining excellent electronic performance. This concept involves introducing chemical moieties to promote dynamic non-covalent crosslinking of the conjugated polymers. These non-covalent covalent crosslinking moieties are able to undergo an energy dissipation mechanism through breakage of bonds when strain ismore » applied, while retaining its high charge transport ability. As a result, our polymer is able to recover its high mobility performance (>1 cm 2/Vs) even after 100 cycles at 100% applied strain. Furthermore, we observed that the polymer can be efficiently repaired and/or healed with a simple heat and solvent treatment. These improved mechanical properties of our fabricated stretchable semiconductor enabled us to fabricate highly stretchable and high performance wearable organic transistors. This material design concept should illuminate and advance the pathways for future development of fully stretchable and healable skin-inspired wearable electronics.« less

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

NASA Astrophysics Data System (ADS)

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.

Intrinsically stretchable and healable semiconducting polymer for organic transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oh, Jin Young; Rondeau-Gagné, Simon; Chiu, Yu-Cheng

Developing a molecular design paradigm for conjugated polymers applicable to intrinsically stretchable semiconductors is crucial toward the next generation of wearable electronics. Current molecular design rules for high charge carrier mobility semiconducting polymers are unable to render the fabricated devices simultaneously stretchable and mechanically robust. Here in this paper, we present a new design concept to address the above challenge, while maintaining excellent electronic performance. This concept involves introducing chemical moieties to promote dynamic non-covalent crosslinking of the conjugated polymers. These non-covalent covalent crosslinking moieties are able to undergo an energy dissipation mechanism through breakage of bonds when strain ismore » applied, while retaining its high charge transport ability. As a result, our polymer is able to recover its high mobility performance (>1 cm 2/Vs) even after 100 cycles at 100% applied strain. Furthermore, we observed that the polymer can be efficiently repaired and/or healed with a simple heat and solvent treatment. These improved mechanical properties of our fabricated stretchable semiconductor enabled us to fabricate highly stretchable and high performance wearable organic transistors. This material design concept should illuminate and advance the pathways for future development of fully stretchable and healable skin-inspired wearable electronics.« less

Theoretical study of spin Hall effect in conjugated Organic semiconductors

NASA Astrophysics Data System (ADS)

Mahani, M. R.; Delin, A.

The spin Hall effect (SHE), a direct conversion between electronic and spin currents, is a rapidly growing branch of spintronics. The study of SHE in conjugated polymers has gained momentum recently due to the weak spin-orbit couplings and hyperfine interactions in these materials. Our calculations of SHE based on the recent work, are the result of the misalignment of pi-orbitals in triads consisting of three molecules. In disordered organics, where the electronic conduction is through hopping of the electrons among randomly oriented molecules, instead of identifying a hopping triad to represent the entire system, we numerically solve the master equations for electrical and spin hall conductivities by summing the contributions from all triads in a sufficiently large system. The interference between the direct and indirect hoppings in these triads leads to SHE proportional to the orientation vector of molecule at the first order of spin-orbit coupling. Hence, our results show, the degree of molecular alignment as well as the strength of the spin-orbit coupling can be used to control the SHE in organics.

Optoelectronic Properties of Conjugated Block Copolymer with Flexible Linking Group

NASA Astrophysics Data System (ADS)

Hu, Zhiqi; Verduzco, Rafael

State-of-the-art organic photovoltaics (OPVs) are prepared by depositing a disordered, co-continuous donor and acceptor blend. While optimization of material processing has produced significant improvements in performance, a fundamental understanding of charge separation and recombination at the donor/acceptor interface is lacking. Block copolymers with donor and acceptor polymer blocks provide an opportunity for controlling the donor-accepter interfacial structure and understanding its relationship to charge separation and photovoltaic performance. Here, we report the synthesis and characterization of donor-linker-acceptor block copolymers for use in OPVs. A series of poly(3-hexylthiophene)-block- poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (P3HT-linkerPFTBT) are synthesized with flexible oligo-ethylene glycol (PEG) linkers. Photoluminescence measurements demonstrate that the insertion of a non-conjugated linker has a significant impact on energy transfer between the two blocks, and the block copolymers are used as additives for bulk heterojunction OPVs. This work provides insight into the charge separation process and demonstrates a technique for tailoring the donor-accepter interface in OPVs.

An experimental study of the electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles and their electrosynthesized polymers.

PubMed

Diaw, A K D; Gningue-Sall, D; Yassar, A; Brochon, J-C; Henry, E; Aaron, J-J

2015-01-25

Electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles (N-PhPys), including HOPhPy, MeOPhPy, ThPhPy, PhDPy, DPhDPy, PyPhThThPhPy, and their available, electrosynthesized polymers were investigated. Electronic absorption spectra, fluorescence excitation and emission spectra, fluorescence quantum yields (ΦF) and lifetimes (τF), and other photophysical parameters of these N-PhPy derivatives and their polymers were measured in DMF, DMSO diluted solutions and/or solid state at room temperature. The electronic absorption spectra of N-PhPy derivatives and their polymers included one to several bands, located in the 270-395 nm region, according to the p-phenyl substituent electron-donating effect and conjugated heteroaromatic system length. The fluorescence excitation spectra were characterized by one broad main peak, with, in most cases, one (or more) poorly resolved shoulder (s), appearing in the 270-405 nm region, and their emission spectra were generally constituted of several bands located in the 330-480 nm region. No significant shift of the absorption, fluorescence excitation and emission spectra wavelengths was found upon going from the monomers to the corresponding polymers. ΦF values were high, varying between 0.11 and 0.63, according to the nature of substituents(s) and to the conjugated system extension. Fluorescence decays were mono-exponential for the monomers and poly-exponential for PyPhThThPhPy and for polymers. τF values were relatively short (0.35-5.17 ns), and markedly decreased with the electron-donor character of the phenyl group p-substituent and the conjugated system extension. Copyright © 2014 Elsevier B.V. All rights reserved.

Redox polymer and probe DNA tethered to gold electrodes for enzyme-amplified amperometric detection of DNA hybridization.

PubMed

Kavanagh, Paul; Leech, Dónal

2006-04-15

The detection of nucleic acids based upon recognition surfaces formed by co-immobilization of a redox polymer mediator and DNA probe sequences on gold electrodes is described. The recognition surface consists of a redox polymer, [Os(2,2'-bipyridine)2(polyvinylimidazole)(10)Cl](+/2+), and a model single DNA strand cross-linked and tethered to a gold electrode via an anchoring self-assembled monolayer (SAM) of cysteamine. Hybridization between the immobilized probe DNA of the recognition surface and a biotin-conjugated target DNA sequence (designed from the ssrA gene of Listeria monocytogenes), followed by addition of an enzyme (glucose oxidase)-avidin conjugate, results in electrical contact between the enzyme and the mediating redox polymer. In the presence of glucose, the current generated due to the catalytic oxidation of glucose to gluconolactone is measured, and a response is obtained that is binding-dependent. The tethering of the probe DNA and redox polymer to the SAM improves the stability of the surface to assay conditions of rigorous washing and high salt concentration (1 M). These conditions eliminate nonspecific interaction of both the target DNA and the enzyme-avidin conjugate with the recognition surfaces. The sensor response increases linearly with increasing concentration of target DNA in the range of 1 x 10(-9) to 2 x 10(-6) M. The detection limit is approximately 1.4 fmol, (corresponding to 0.2 nM of target DNA). Regeneration of the recognition surface is possible by treatment with 0.25 M NaOH solution. After rehybridization of the regenerated surface with the target DNA sequence, >95% of the current is recovered, indicating that the redox polymer and probe DNA are strongly bound to the surface. These results demonstrate the utility of the proposed approach.

Aqueous Processing for Printed Organic Electronics: Conjugated Polymers with Multistage Cleavable Side Chains.

PubMed

Schmatz, Brian; Yuan, Zhibo; Lang, Augustus W; Hernandez, Jeff L; Reichmanis, Elsa; Reynolds, John R

2017-09-27

The ability to process conjugated polymers via aqueous solution is highly advantageous for reducing the costs and environmental hazards of large scale roll-to-roll processing of organic electronics. However, maintaining competitive electronic properties while achieving aqueous solubility is difficult for several reasons: (1) Materials with polar functional groups that provide aqueous solubility can be difficult to purify and characterize, (2) many traditional coupling and polymerization reactions cannot be performed in aqueous solution, and (3) ionic groups, though useful for obtaining aqueous solubility, can lead to a loss of solid-state order, as well as a screening of any applied bias. As an alternative, we report a multistage cleavable side chain method that combines desirable aqueous processing attributes without sacrificing semiconducting capabilities. Through the attachment of cleavable side chains, conjugated polymers have for the first time been synthesized, characterized, and purified in organic solvents, converted to a water-soluble form for aqueous processing, and brought through a final treatment to cleave the polymer side chains and leave behind the desired electronic material as a solvent-resistant film. Specifically, we demonstrate an organic soluble polythiophene that is converted to an aqueous soluble polyelectrolyte via hydrolysis. After blade coating from an aqueous solution, UV irradiation is used to cleave the polymer's side chains, resulting in a solvent-resistant, electroactive polymer thin film. In application, this process results in aqueous printed materials with utility for solid-state charge transport in organic field effect transistors (OFETs), along with red to colorless electrochromism in ionic media for color changing displays, demonstrating its potential as a universal method for aqueous printing in organic electronics.

How ABA block polymers activate cytochrome c in toluene: molecular dynamics simulation and experimental observation.

PubMed

Chen, Gong; Kong, Xian; Zhu, Jingying; Lu, Diannan; Liu, Zheng

2015-04-28

While the conjugation of enzymes with ABA copolymers has resulted in increased enzymatic activities in organic solvents, by several orders of magnitude, the underpinning mechanism has not been fully uncovered, particularly at the molecular level. In the present work, a coarse-grained molecular dynamics simulation of cytochrome c (Cyt c) conjugated with a PEO-PPO-PEO block copolymer (ABA) in toluene was simulated with Cyt c as a control. It is shown that the hydrophilic segments (PEO) of the conjugated block copolymer molecules tend to entangle around the hydrophilic patch of Cyt c, while the hydrophobic segments (PPO) extend into the toluene. At a lower temperature, the PEO tails tend to form a hairpin structure outside the conjugated protein, whereas the Cyt c-ABA conjugates tend to form larger aggregates. At a higher temperature, however, the PEO tails tend to adsorb onto the hydrophilic protein surface, thus improving the suspension of the Cyt c-ABA conjugates and, consequently, the contact with the substrate. Moreover, the temperature increase drives the conformational transition of the active site of Cyt c-ABA from an "inactive state" to an "activated state" and thus results in an enhanced activity. To validate the above simulations, Cyt c was conjugated to F127, an extensively used ABA copolymer. By elevating the temperature, a decrease in the average size of the Cyt c-F127 conjugates along with a great increase in the apparent activity in toluene was observed, as can be predicted from the molecular dynamics simulation. The above mentioned molecular simulations offer a molecular insight into the temperature-responsive behaviour of protein-ABA copolymers, which is helpful for the design and application of enzyme-polymer conjugates for industrial biocatalysis.

HPMA copolymer-bound doxorubicin induces immunogenic tumor cell death.

PubMed

Sirova, M; Kabesova, M; Kovar, L; Etrych, T; Strohalm, J; Ulbrich, K; Rihova, B

2013-01-01

Treatment of murine EL4 T cell lymphoma with N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer conjugates of doxorubicin (Dox) leads to complete tumor regression and to the development of therapy-dependent longlasting cancer resistance. This phenomenon occurs with two types of Dox conjugates tested, despite differences in the covalent linkage of Dox to the polymer carrier. Such a cancer resistance cannot fully express in conventional treatment with free Dox, due to substantial immunotoxicity of the treatment, which was not observed in the polymer conjugates. In this study, calreticulin (CRT) translocation and high mobility group box-1 protein (HMGB1) release was observed in EL4 cells treated with a conjugate releasing Dox by a pH-dependent manner. As a result, the treated tumor cells were engulfed by dendritic cells (DC) in vitro, and induced their expression of CD80, CD86, and MHC II maturation markers. Conjugates with Dox bound via an amide bond only increased translocation of HSPs to the membrane, which led to an elevated phagocytosis but was not sufficient to induce increase of the maturation markers on DCs in vitro. Both types of conjugates induced engulfment of the target tumor cells in vivo, that was more intense than that seen with free Dox. It means that the induction of anti-tumor immunity documented upon treatment of EL4 lymphoma with HPMA-bound Dox conjugates does not rely solely on CRT-mediated cell death, but involves multiple mechanisms.

Synthesis, electronic structure, molecular packing/morphology evolution, and carrier mobilities of pure oligo-/poly(alkylthiophenes).

PubMed

Zhang, Lei; Colella, Nicholas S; Liu, Feng; Trahan, Stephan; Baral, Jayanta K; Winter, H Henning; Mannsfeld, Stefan C B; Briseno, Alejandro L

2013-01-16

Monodispersed conjugated oligothiophenes are receiving attention in fundamental and applied science due to their interesting optical, optoelectronic, and charge transport properties. These "low molecular weight" polymers serve as model structures for the corresponding polymer analogues, which are inherently polydispersed. Here we report the synthesis, electronic structure, molecular packing/morphology, and charge transport properties of monodispersed oligothiophenes with up to six didodecylquaterthiophene (DDQT) building block repeat units (i.e., 24 thiophene units). At the point where the effective conjugation length is reached, the electronic structure showed convergence behavior to the corresponding polymer, poly(3,3"-didodecyl-quaterthiophene) (PQT-12). X-ray crystal structure analysis of the dimer (DDQT-2) showed that terminal thiophenes exhibit syn-conformations, similar to the terminal syn-conformations observed in the trimer (DDQT-3). The dimer also exhibits a rare bending of the terminal alkyl side chains in order to prevent steric hindrance with neighboring hydrogens attached to core thiophenes. Grazing incidence X-ray scattering measurements revealed a morphology evolution from small molecule-like packing to polymer-like packing in thin films, with a morphology transition occurring near the effective conjugation length. Charge transport measurements showed a mobility increase with decreasing chain length. We correlated the molecular packing and morphology to charge transport and determined that carrier mobilities are most sensitive to crystallinity and crystal grain misorientation. This indicates that molecular weight is not a decisive factor for improved carrier mobility in the low molecular weight region, but rather the degree in crystallinity and in-plane crystal orientation. These results represent a fundamental advancement in understanding the relationship between conjugation length and carrier mobilities in oligothiophene semiconductors.

Hepatoma targeting peptide conjugated bio-reducible polymer complexed with oncolytic adenovirus for cancer gene therapy.

PubMed

Choi, Joung-Woo; Kim, Hyun Ah; Nam, Kihoon; Na, Youjin; Yun, Chae-Ok; Kim, SungWan

2015-12-28

Despite adenovirus (Ad) vector's numerous advantages for cancer gene therapy, such as high ability of endosomal escape, efficient nuclear entry mechanism, and high transduction, and therapeutic efficacy, tumor specific targeting and antiviral immune response still remain as a critical challenge in clinical setting. To overcome these obstacles and achieve cancer-specific targeting, we constructed tumor targeting bioreducible polymer, an arginine grafted bio-reducible polymer (ABP)-PEG-HCBP1, by conjugating PEGylated ABP with HCBP1 peptides which has high affinity and selectivity towards hepatoma. The ABP-PEG-HCBP1-conjugated replication incompetent GFP-expressing ad, (Ad/GFP)-ABP-PEG-HCBP1, showed a hepatoma cancer specific uptake and transduction compared to either naked Ad/GFP or Ad/GFP-ABP. Competition assays demonstrated that Ad/GFP-ABP-PEG-HCBP1-mediated transduction was specifically inhibited by HCBP1 peptide rather than coxsackie and adenovirus receptor specific antibody. In addition, ABP-PEG-HCBP1 can protect biological activity of Ad against serum, and considerably reduced both innate and adaptive immune response against Ad. shMet-expressing oncolytic Ad (oAd; RdB/shMet) complexed with ABP-PEG-HCBP1 delivered oAd efficiently into hepatoma cancer cells. The oAd/ABP-PEG-HCBP1 demonstrated enhanced cancer cell killing efficacy in comparison to oAd/ABP complex. Furthermore, Huh7 and HT1080 cancer cells treated with oAd/shMet-ABP-PEG-HCBP1 complex had significantly decreased Met and VEGF expression in hepatoma cancer, but not in non-hepatoma cancer. In sum, these results suggest that HCBP1-conjugated bioreducible polymer could be used to deliver oncolytic Ad safely and efficiently to treat hepatoma. Copyright © 2015 Elsevier B.V. All rights reserved.

Hepatoma targeting peptide conjugated bio-reducible polymer complexed with oncolytic adenovirus for cancer gene therapy

PubMed Central

Choi, Joung-Woo; Kim, Hyun Ah; Nam, Kihoon; Na, Youjin; Yun, Chae-Ok; Kim, SungWan

2015-01-01

Despite adenovirus (Ad) vector’s numerous advantages for cancer gene therapy, such as high ability of endosomal escape, efficient nuclear entry mechanism, and high transduction, and therapeutic efficacy, tumor specific targeting and antiviral immune response still remain as a critical challenge in clinical setting. To overcome these obstacles and achieve cancer-specific targeting, we constructed tumor targeting bioreducible polymer, an arginine grafted bio-reducible polymer (ABP)-PEG-HCBP1, by conjugating PEGylated ABP with HCBP1 peptides which has high affinity and selectivity towards hepatoma. The ABP-PEG-HCBP1-conjugated replication incompetent GFP-expressing ad, (Ad/GFP)-ABP-PEG-HCBP1, showed a hepatoma cancer specific uptake and transduction compared to either naked Ad/GFP or Ad/GFP-ABP. Competition assays demonstrated that Ad/GFP-ABP-PEG-HCBP1-mediated transduction was specifically inhibited by HCBP1 peptide rather than coxsackie and adenovirus receptor specific antibody. In addition, ABP-PEG-HCBP1 can protect biological activity of Ad against serum, and considerably reduced both innate and adaptive immune response against Ad. shMet-expressing oncolytic Ad (oAd; RdB/shMet) complexed with ABP-PEG-HCBP1 delivered oAd efficiently into hepatoma cancer cells. The oAd/ABP-PEG-HCBP1 demonstrated enhanced cancer cell killing efficacy in comparison to oAd/ABP complex. Furthermore, Huh7 and HT1080 cancer cells treated with oAd/shMet-ABP-PEG-HCBP1 complex had significantly decreased Met and VEGF expression in hepatoma cancer, but not in non-hepatoma cancer. In sum, these results suggest that HCBP1-conjugated bioreducible polymer could be used to deliver oncolytic Ad safely and efficiently to treat hepatoma. PMID:26437261

Engineered Polymers for Advanced Drug Delivery

PubMed Central

Kim, Sungwon; Kim, Jong-Ho; Jeon, Oju; Kwon, Ick Chan; Park, Kinam

2009-01-01

Engineered polymers have been utilized for developing advanced drug delivery systems. The development of such polymers has caused advances in polymer chemistry, which, in turn, has resulted in smart polymers that can respond to changes in environmental condition, such as temperature, pH, and biomolecules. The responses vary widely from swelling/deswelling to degradation. Drug-polymer conjugates and drug-containing nano/micro-particles have been used for drug targeting. Engineered polymers and polymeric systems have also been used in new areas, such as molecular imaging as well as in nanotechnology. This review examines the engineered polymers that have been used as traditional drug delivery and as more recent applications in nanotechnology. PMID:18977434

Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics

NASA Astrophysics Data System (ADS)

Tautz, Raphael; da Como, Enrico; Limmer, Thomas; Feldmann, Jochen; Egelhaaf, Hans-Joachim; von Hauff, Elizabeth; Lemaur, Vincent; Beljonne, David; Yilmaz, Seyfullah; Dumsch, Ines; Allard, Sybille; Scherf, Ullrich

2012-07-01

Polymeric semiconductors are materials where unique optical and electronic properties often originate from a tailored chemical structure. This allows for synthesizing conjugated macromolecules with ad hoc functionalities for organic electronics. In photovoltaics, donor-acceptor co-polymers, with moieties of different electron affinity alternating on the chain, have attracted considerable interest. The low bandgap offers optimal light-harvesting characteristics and has inspired work towards record power conversion efficiencies. Here we show for the first time how the chemical structure of donor and acceptor moieties controls the photogeneration of polaron pairs. We show that co-polymers with strong acceptors show large yields of polaron pair formation up to 24% of the initial photoexcitations as compared with a homopolymer (η=8%). π-conjugated spacers, separating the donor and acceptor centre of masses, have the beneficial role of increasing the recombination time. The results provide useful input into the understanding of polaron pair photogeneration in low-bandgap co-polymers for photovoltaics.

Preparation and in vitro evaluation of folate-receptor-targeted SPION-polymer micelle hybrids for MRI contrast enhancement in cancer imaging

NASA Astrophysics Data System (ADS)

Mahajan, Shveta; Koul, Veena; Choudhary, Veena; Shishodia, Gauri; Bharti, Alok C.

2013-01-01

Polymer-SPION hybrids were investigated for receptor-mediated localization in tumour tissue. Superparamagnetic iron oxide nanoparticles (SPIONs) prepared by high-temperature decomposition of iron acetylacetonate were monodisperse (9.27 ± 3.37 nm), with high saturation magnetization of 76.8 emu g-1. Amphiphilic copolymers prepared from methyl methacrylate and PEG methacrylate by atom transfer radical polymerization were conjugated with folic acid (for folate-receptor specificity). The folate-conjugated polymer had a low critical micellar concentration (0.4 mg l-1), indicating stability of the micellar formulation. SPION-polymeric micelle clusters were prepared by desolvation of the SPION dispersion/polymer solution in water. Magnetic resonance imaging of the formulation revealed very good contrast enhancement, with transverse (T2) relaxivity of 260.4 mM-1 s-1. The biological evaluation of the SPION micelles included cellular viability assay (MTT) and uptake in HeLa cells. These studies demonstrated the potential use of these nanoplatforms for imaging and targeting.

Distinct Interfacial Fluorescence in Oil-in-Water Emulsions via Exciton Migration of Conjugated Polymers.

PubMed

Koo, Byungjin; Swager, Timothy M

2017-09-01

Commercial dyes are extensively utilized to stain specific phases for the visualization applications in emulsions and bioimaging. In general, dyes emit only one specific fluorescence signal and thus, in order to stain various phases and/or interfaces, one needs to incorporate multiple dyes and carefully consider their compatibility to avoid undesirable interactions with each other and with the components in the system. Herein, surfactant-type, perylene-endcapped fluorescent conjugated polymers that exhibit two different emissions are reported, which are cyan in water and red at oil-water interfaces. The interfacially distinct red emission results from enhanced exciton migration from the higher-bandgap polymer backbone to the lower-bandgap perylene endgroup. The confocal microscopy images exhibit the localized red emission exclusively from the circumference of oil droplets. This exciton migration and dual fluorescence of the polymers in different physical environments can provide a new concept of visualization methods in many amphiphilic colloidal systems and bioimaging. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

PubMed Central

Cantu, Travis; Rodier, Bradley; Iszard, Zachary; Kilian, Alissa; Pattani, Varun; Walsh, Kyle; Weber, Katharina; Tunnell, James; Betancourt, Tania; Irvin, Jennifer

2016-01-01

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT). PMID:26780244

Enhancement of the Power-Conversion Efficiency of Organic Solar Cells via Unveiling an Appropriate Rational Design Strategy in Indacenodithiophene- alt-quinoxaline π-Conjugated Polymers.

PubMed

Chochos, Christos L; Singh, Ranbir; Gregoriou, Vasilis G; Kim, Min; Katsouras, Athanasios; Serpetzoglou, Efthymis; Konidakis, Ioannis; Stratakis, Emmanuel; Cho, Kilwon; Avgeropoulos, Apostolos

2018-03-28

We report on the photovoltaic parameters, photophysical properties, optoelectronic properties, self-assembly, and morphology variations in a series of high-performance donor-acceptor (D-A) π-conjugated polymers based on indacenodithiophene and quinoxaline moieties as a function of the number-average molecular weight ([Formula: see text]), the nature of aryl substituents, and the enlargement of the polymer backbone. One of the most important outcome is that from the three optimization approaches followed to tune the chemical structure toward enhanced photovoltaic performance in bulk heterojunction solar cell devices with the fullerene derivative [6,6]-phenyl-C 71 -butyric acid methyl ester as the electron acceptor, the choice of the aryl substituent is the most efficient rational design strategy. Incorporation of thienyl rings as substituents versus phenyl rings accelerates the electron-hole extraction process to the respective electrode, despite the slightly lower recombination lifetime and, thus, improves the electrical performance of the device. Single-junction solar cells based on ThIDT-TQxT feature a maximum power-conversion efficiency of 7.26%. This study provides significant insights toward understanding of the structure-properties-performance relationship for D-A π-conjugated polymers in solid state, which provide helpful inputs for the design of next-generation polymeric semiconductors for organic solar cells with enhanced performance.

Functional nanocomposites prepared by self-assembly and polymerization of diacetylene surfactants and silicic acid

NASA Technical Reports Server (NTRS)

Yang, Yi; Lu, Yunfeng; Lu, Mengcheng; Huang, Jinman; Haddad, Raid; Xomeritakis, George; Liu, Nanguo; Malanoski, Anthony P.; Sturmayr, Dietmar; Fan, Hongyou;

Stable and Efficient Organo-Metal Halide Hybrid Perovskite Solar Cells via π-Conjugated Lewis Base Polymer Induced Trap Passivation and Charge Extraction.

PubMed

Qin, Ping-Li; Yang, Guang; Ren, Zhi-Wei; Cheung, Sin Hang; So, Shu Kong; Chen, Li; Hao, Jianhua; Hou, Jianhui; Li, Gang

2018-03-01

High-quality pinhole-free perovskite film with optimal crystalline morphology is critical for achieving high-efficiency and high-stability perovskite solar cells (PSCs). In this study, a p-type π-conjugated polymer poly[(2,6-(4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)-benzo[1,2-b:4,5-b'] dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl) benzo[1',2'-c:4',5'-c'] dithiophene-4,8-dione))] (PBDB-T) is introduced into chlorobenzene to form a facile and effective template-agent during the anti-solvent process of perovskite film formation. The π-conjugated polymer PBDB-T is found to trigger a heterogeneous nucleation over the perovskite precursor film and passivate the trap states of the mixed perovskite film through the formation of Lewis adducts between lead and oxygen atom in PBDB-T. The p-type semiconducting and hydrophobic PBDB-T polymer fills in the perovskite grain boundaries to improve charge transfer for better conductivity and prevent moisture invasion into the perovskite active layers. Consequently, the PSCs with PBDB-T modified anti-solvent processing leads to a high-efficiency close to 20%, and the devices show excellent stability, retaining about 90% of the initial power conversion efficiency after 150 d storage in dry air. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.