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Polymer Chemistry

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https://www.readbyqxmd.com/read/28496524/long-term-stability-and-reusability-of-molecularly-imprinted-polymers
#1
Jozsef Kupai, Mayamin Razali, Sibel Buyuktiryaki, Rustem Kecili, Gyorgy Szekely
Molecularly imprinted materials are man-made mimics of biological receptors. Their polymer network has recognition sites complementary to a substrate in terms of size, shape and chemical functionality. They have diverse applications in various chemical, biomedical and engineering fields such as solid phase extraction, catalysis, drug delivery, pharmaceutical purification, (bio)sensors, water treatment, membrane separations and proteomics. The stability and reusability of molecularly imprinted polymers (IPs) have crucial roles in developing applications that are reliable, economic and sustainable...
January 28, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/28596807/aqueous-sara-atrp-using-inorganic-sulfites
#2
Carlos M R Abreu, Liye Fu, Sheiliza Carmali, Arménio C Serra, Krzysztof Matyjaszewski, Jorge F J Coelho
Aqueous supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) using inorganic sulfites was successfully carried out for the first time. Under optimized conditions, a well-controlled poly[oligo(ethylene oxide) methyl ether acrylate] (POEOA) was obtained with <30 ppm of soluble copper catalyst using tris(2-pyridylmethyl)amine (TPMA) ligand in the presence of an excess of halide salts (e.g. NaCl). Inorganic sulfites (e.g. Na2S2O4) were continuously fed into the reaction mixture...
January 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/28261331/a-biocompatible-macromolecular-two-photon-initiator-based-on-hyaluronan
#3
Maximilian Tromayer, Peter Gruber, Marica Markovic, Arnulf Rosspeintner, Eric Vauthey, Heinz Redl, Aleksandr Ovsianikov, Robert Liska
The possibility of the direct encapsulation of living cells via two-photon induced photopolymerization enables the microfabrication of hydrogel scaffolds with high initial cell loadings and intimate matrix-cell contact. While highly efficient water-soluble two-photon initiators based on benzylidene ketone dyes have been developed, they exhibit considerable cyto- and phototoxicity. To address the problem of photoinitiator migration from the extracellular matrix into the cytosol, a two-photon initiator bound to a polymeric hyaluronan backbone (HAPI) was synthesized in this work...
January 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/28496523/probing-the-causes-of-thermal-hysteresis-using-tunable-nagg-micelles-with-linear-and-brush-like-thermoresponsive-coronas
#4
L D Blackman, M I Gibson, R K O'Reilly
Self-assembled thermoresponsive polymers in aqueous solution have great potential as smart, switchable materials for use in biomedical applications. In recent years, attention has turned to the reversibility of these polymers' thermal transitions, which has led to debate over what factors influence discrepancies in the transition temperature when heating the system compared to the temperature obtained when cooling the system, known as the thermal hysteresis. Herein, we synthesize micelles with tunable aggregation numbers (Nagg) whose cores contain poly(n-butyl acrylate-co-N,N-dimethylacrylamide) (p(nBA-co-DMA)) and four different thermoresponsive corona blocks, namely poly(N-isopropylacrylamide) (pNIPAM), poly(N,N-diethylacrylamide) (pDEAm), poly(diethylene glycol monomethyl ether methacrylate) (pDEGMA) and poly(oligo(ethylene glycol) monomethyl ether methacrylate) (pOEGMA)...
January 1, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/28348639/brushed-polyethylene-glycol-and-phosphorylcholine-for-grafting-nanoparticles-against-protein-binding
#5
Bo Wang, Thomas Blin, Aleksandr Käkinen, Xinwei Ge, Emily H Pilkington, John F Quinn, Michael R Whittaker, Thomas P Davis, Pu Chun Ke, Feng Ding
To provide a molecular insight for guiding polymer coating in surface science and nanotechnology, here we examined the structures of brushed polyethylene glycol(bPEG)- and phosphorylcholine(bPC)-grafted iron oxide nanoparticles and analyzed their protein avoiding properties. We show bPC as an advantageous biomimetic alternative to PEG in rendering stealth nanostructures.
December 7, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/27795740/pillar-5-arene-based-amphiphilic-supramolecular-brush-copolymer-fabrication-controllable-self-assembly-and-application-in-self-imaging-targeted-drug-delivery
#6
Guocan Yu, Run Zhao, Dan Wu, Fuwu Zhang, Li Shao, Jiong Zhou, Jie Yang, Guping Tang, Xiaoyuan Chen, Feihe Huang
Supramolecular brush copolymers have attracted continuing interest due to their unusual architectures, fascinating properties, and potential applications in many fields involving smart stimuli-responsive drug delivery systems. Herein, the first pillararene-based amphiphilic supramolecular brush copolymer (P5-PEG-Biotin⊃PTPE) was constructed on the basis of the host-guest molecular recognition between a water-soluble pillar[5]arene (P5) and a viologen salt (M). P5-PEG-Biotin⊃PTPE self-assembled into supramolecular nanoparticles (SNPs), which were utilized as a self-imaging drug delivery vehicle by taking advantage of the aggregation-induced emission (AIE) effect...
October 28, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/28239425/block-ionomer-complexes-consisting-of-sirna-and-araft-synthesized-hydrophilic-block-cationic-copolymers-ii-the-influence-of-cationic-block-charge-density-on-gene-suppression
#7
Keith H Parsons, Andrew C Holley, Gabrielle A Munn, Alex S Flynt, Charles L McCormick
Block ionomer complex (BIC)-siRNA interactions and effectiveness in cell transfection are reported. Aqueous RAFT polymerization was used to prepare a series of hydrophilic-block-cationic copolymers in which the cationic block statistically incorporates increasing amounts of neutral, hydrophilic monomer such that the number of cationic groups remains unchanged but the cationic charge density is diluted along the polymer backbone. Reduced charge density decreases the electrostatic binding strength between copolymers and siRNA with the goal of improving siRNA release after targeted cellular delivery...
October 21, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/28239424/non-covalent-interactions-in-controlling-ph-responsive-behaviors-of-self-assembled-nanosystems
#8
Yang Li, Zhaohui Wang, Qi Wei, Min Luo, Gang Huang, Baran D Sumer, Jinming Gao
Self-assembly and associated dynamic and reversible non-covalent interactions are the basis of protein biochemistry (e.g., protein folding) and development of sophisticated nanomaterial systems that can respond to and amplify biological signals. In this study, we report a systematic investigation of non-covalent interactions that affect the pH responsive behaviors and resulting supramolecular self-assembly of a series of ultra-pH sensitive (UPS) block copolymers. Increase of hydrophobic and π-π stacking interactions led to the decrease of pKa values...
October 14, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/27833665/mitochondria-targeted-fluorescent-polymersomes-for-drug-delivery-to-cancer-cells
#9
P S Kulkarni, M K Haldar, M I Confeld, C J Langaas, X Yang, S Y Qian, S Mallik
Mitochondria is an attractive target to deliver anticancer drugs. We have synthesized a cationic triphenylphosphonium ion conjugated fluorescent polymer which self-assembles into nanosized polymersomes and targets the encapsulated anticancer drug doxorubicin to cancer cell mitochondria.
July 7, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/27358655/use-of-complementary-nucleobase-containing-synthetic-polymers-to-prepare-complex-self-assembled-morphologies-in-water
#10
Yan Kang, Anaïs Pitto-Barry, Marianne S Rolph, Zan Hua, Ian Hands-Portman, Nigel Kirby, Rachel K O'Reilly
Amphiphilic nucleobase-containing block copolymers with poly(oligo(ethylene glycol) methyl ether methacrylate) as the hydrophilic block and nucleobase-containing blocks as the hydrophobic segments were successfully synthesized using RAFT polymerization and then self-assembled via solvent switch in aqueous solutions. Effects of the common solvent on the resultant morphologies of the adenine (A) and thymine (T) homopolymers, and A/T copolymer blocks and blends were investigated. These studies highlighted that depending on the identity of the common solvent, DMF or DMSO, spherical micelles or bicontinuous micelles were obtained...
April 28, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/27148427/enzyme-responsive-polyion-complex-pic-nanoparticles-for-the-targeted-delivery-of-antimicrobial-polymers
#11
Ignacio Insua, Evangelos Liamas, Zhenyu Zhang, Anna F A Peacock, Anne Marie Krachler, Francisco Fernandez-Trillo
Here we present new enzyme-responsive polyion complex (PIC) nanoparticles prepared from antimicrobial poly(ethylene imine) and an anionic enzyme-responsive peptide targeting Pseudomonas aeruginosa's elastase. The synthetic conditions used to prepare these nanomaterials allowed us to optimise particle size and charge, and their stability under physiological conditions. We demonstrate that these enzyme responsive PIC nanoparticles are selectively degraded in the presence of P. aeruginosa elastase without being affected by other endogenous elastases...
April 21, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/27478513/core-functionalization-of-semi-crystalline-polymeric-cylindrical-nanoparticles-using-photo-initiated-thiol-ene-radical-reactions
#12
Liang Sun, Anaïs Pitto-Barry, Anthony W Thomas, Maria Inam, Kay Doncom, Andrew P Dove, Rachel K O'Reilly
Sequential ring-opening and reversible addition-fragmentation chain transfer (RAFT) polymerization was used to form a triblock copolymer of tetrahydropyran acrylate (THPA), 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one (MAC) and l-lactide. Concurrent deprotection of the THPA block and crystallization-driven self-assembly (CDSA) was undertaken and allowed for the formation of cylindrical micelles bearing allyl handles in a short outer core segment. These handles were further functionalized by different thiols using photo-initiated thiol-ene radical reactions to demonstrate that the incorporation of an amorphous PMAC block within the core does not disrupt CDSA and can be used to load the cylindrical nanoparticles with cargo...
April 7, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/27110293/enhancing-conjugation-yield-of-brush-polymer-protein-conjugates-by-increasing-linker-length-at-the-polymer-end-group
#13
Peter C Nauka, Juneyoung Lee, Heather D Maynard
Polymers with oligoethylene glycol side chains are promising in therapeutic protein-polymer conjugates as replacements for linear polyethylene glycol (PEG). Branched PEG polymers can confer additional stability and advantageous properties compared to linear PEGs. However, branched PEG polymers suffer from low conjugation yields to proteins, likely due to steric interactions between bulky side chains of the polymer and the protein. In an effort to increase yields, the linker length between the protein-reactive functional end-group of the polymer chain and branched PEG side chain was systematically increased...
April 7, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/28496522/synthesis-characterisation-and-pickering-emulsifier-performance-of-poly-stearyl-methacrylate-poly-n-2-methacryloyloxy-ethyl-pyrrolidone-diblock-copolymer-nano-objects-via-raft-dispersion-polymerisation-in-n-dodecane
#14
V J Cunningham, S P Armes, O M Musa
A near-monodisperse poly(stearyl methacrylate) macromolecular chain transfer agent (PSMA macro-CTA) was prepared via reversible addition-fragmentation chain transfer (RAFT) solution polymerisation in toluene. This PSMA macro-CTA was then utilised as a stabiliser block for the RAFT dispersion polymerisation of a highly polar monomer, N-2-(methacryloyloxy)ethyl pyrrolidone (NMEP), in n-dodecane at 90 °C. (1)H NMR studies confirmed that the rate of NMEP polymerisation was significantly faster than that of a non-polar monomer (benzyl methacrylate, BzMA) under the same conditions...
March 14, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/28003855/activation-of-ice-recrystallization-inhibition-activity-of-poly-vinyl-alcohol-using-a-supramolecular-trigger
#15
Daniel J Phillips, Thomas R Congdon, Matthew I Gibson
Antifreeze (glyco)proteins (AF(G)Ps) have potent ice recrystallisation inhibition (IRI) activity - a desirable phenomenon in applications such as cryopreservation, frozen food and more. In Nature AF(G)P activity is regulated by protein expression levels in response to an environmental stimulus; temperature. However, this level of regulation is not possible in synthetic systems. Here, a synthetic macromolecular mimic is introduced, using supramolecular assembly to regulate activity. Catechol-terminated poly(vinyl alcohol) was synthesised by RAFT polymerization...
March 7, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/26918033/blending-block-copolymer-micelles-in-solution-obstacles-of-blending
#16
Daniel B Wright, Joseph P Patterson, Nathan C Gianneschi, Christophe Chassenieux, Olivier Colombani, Rachel K O'Reilly
Amphiphilic block copolymers can assemble into a variety of structures on the nanoscale in selective solvent. The micelle blending protocol offers a simple unique route to reproducibly produce polymer nanostructures. Here we expand this blending protocol to a range of polymer micelle systems and self-assembly routes. We found by exploring a range of variables that the systems must be able to reach global equilibrium at some point for the blending protocol to be successful. Our results demonstrate the kinetics requirements, specifically core block glass transition temperature, Tg, and length of the block limiting the exchange rates, for the blending protocol which can then be applied to a wide range of polymer systems to access this simple protocol for polymer self-assembly...
February 28, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/27066114/combined-independent-small-molecule-release-and-shape-memory-via-nanogel-coated-thiourethane-polymer-networks
#17
Eric A Dailing, Devatha P Nair, Whitney K Setterberg, Kyle A Kyburz, Chun Yang, Tyler D'Ovidio, Kristi S Anseth, Jeffrey W Stansbury
Drug releasing shape memory polymers (SMPs) were prepared from poly(thiourethane) networks that were coated with drug loaded nanogels through a UV initiated, surface mediated crosslinking reaction. Multifunctional thiol and isocyanate monomers were crosslinked through a step-growth mechanism to produce polymers with a homogeneous network structure that exhibited a sharp glass transition with 97% strain recovery and 96% shape fixity. Incorporating a small stoichiometric excess of thiol groups left pendant functionality for a surface coating reaction...
January 28, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/27004068/%C3%AE-tocopheryl-succinate-based-amphiphilic-block-copolymers-obtained-by-raft-and-their-nanoparticles-for-the-treatment-of-cancer
#18
Raquel Palao-Suay, María Rosa Aguilar, Francisco J Parra-Ruiz, Samarendra Maji, Richard Hoogenboom, N A Rohner, Susan N Thomas, Julio San Román
α-Tocopheryl succinate (α-TOS) is a well-known mitochondrially targeted anticancer compound. However, the major factor limiting the use of α-TOS is its low solubility in physiological media. To overcome this problem, the aim of this work is the preparation of new polymeric and active α-TOS-based nanovehicle with a precise control over its macromolecular architecture. Reversible addition-fragmentation chain transfer polymerization (RAFT) is used to synthesize an α-TOS amphiphilic block copolymer with highly homogeneous molecular weight and relatively narrow dispersity...
January 28, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/27429650/kinetics-of-bulk-photo-initiated-copper-i-catalyzed-azide-alkyne-cycloaddition-cuaac-polymerizations
#19
Han Byul Song, Austin Baranek, Christopher N Bowman
Photoinitiation of polymerizations based on the copper(i)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction enables spatio-temporal control and the formation of mechanically robust, highly glassy photopolymers. Here, we investigated several critical factors influencing photo-CuAAC polymerization kinetics via systematic variation of reaction conditions such as the physicochemical nature of the monomers; the copper salt and photoinitiator types and concentrations; light intensity; exposure time and solvent content...
January 21, 2016: Polymer Chemistry
https://www.readbyqxmd.com/read/26755925/uv-vis-ft-nir-in-situ-monitoring-of-visible-light-induced-polymerization-of-pegda-hydrogels-initiated-by-eosin-triethanolamine-o2
#20
Kaja Kaastrup, Alan Aguirre-Soto, Chen Wang, Christopher N Bowman, Jeffery Stansbury, Hadley D Sikes
In conjunction with a tertiary amine coinitiator, eosin, a photoreducible dye, has been shown to successfully circumvent oxygen inhibition in radical photopolymerization reactions. However, the role of O2 in the initiation and polymerization processes remains inconclusive. Here, we employ a UV-Vis/FT-NIR analytical tool for real-time, simultaneous monitoring of chromophore and monomer reactive group concentrations to investigate the eosin-activated photopolymerization of PEGDA-based hydrogels under ambient conditions...
2016: Polymer Chemistry
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