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ACS Macro Letters

Jan Smrek, Kurt Kremer, Angelo Rosa
Unconcatenated ring polymers in concentrated solutions and melt are remarkably well described as double-folded conformations on randomly branched primitive trees. This picture though contrasts recent evidence for extensive intermingling between close-by rings in the form of long-lived topological constraints or threadings. Here, we employ the concept of ring minimal surface to quantify the extent of threadings in polymer solutions of the double-folded rings vs rings in equilibrated molecular dynamics computer simulations...
February 19, 2019: ACS Macro Letters
A Pia P Kröger, Muhabbat I Komil, Naomi M Hamelmann, Alberto Juan, Martina H Stenzel, Jos M J Paulusse
Naturally occurring glycoconjugates possess carbohydrate moieties that fulfill essential roles in many biological functions. Through conjugation of carbohydrates to therapeutics or imaging agents, naturally occurring glycoconjugates are mimicked and efficient targeting or increased cellular uptake of glycoconjugated macromolecules is achieved. In this work, linear and cyclic glucose moieties were functionalized with methacrylates via enzymatic synthesis and used as building blocks for intramolecular cross-linked single-chain glycopolymer nanoparticles (glyco-SCNPs)...
January 15, 2019: ACS Macro Letters
Jonna Hynynen, Emmy Järsvall, Renee Kroon, Yadong Zhang, Stephen Barlow, Seth R Marder, Martijn Kemerink, Anja Lund, Christian Müller
The thermoelectric power factor of a broad range of organic semiconductors scales with their electrical conductivity according to a widely obeyed power law, and therefore, strategies that permit this empirical trend to be surpassed are highly sought after. Here, tensile drawing of the conjugated polymer poly(3-hexylthiophene) (P3HT) is employed to create free-standing films with a high degree of uniaxial alignment. Along the direction of orientation, sequential doping with a molybdenum tris(dithiolene) complex leads to a 5-fold enhancement of the power factor beyond the predicted value, reaching up to 16 μW m-1 K-2 for a conductivity of about 13 S cm-1 ...
January 15, 2019: ACS Macro Letters
Laura E Wilkins, Nezha Badi, Filip Du Prez, Matthew I Gibson
Multivalent glycomaterials show high affinity toward lectins but are often nonselective as they lack the precise 3-D presentation found in native glycans. Here, thiolactone chemistry is exploited to enable the synthesis of glycopolymers with both a primary binding (galactose) and a variable secondary binding unit in close proximity to each other on the linker. These polymers are used to target the Cholera toxin B subunit, CTxB, inspired by its native branched glycan target, GM-1. The secondary, nonbinding unit was shown to dramatically modulate affinity and selectivity toward the Cholera toxin...
December 18, 2018: ACS Macro Letters
Shoupeng Cao, Loai K E A Abdelmohsen, Jingxin Shao, Joep van den Dikkenberg, Enrico Mastrobattista, David S Williams, Jan C M van Hest
Herein we describe biodegradable nanovectors comprised of block copolymers of poly(ethylene glycol) and poly(trimethylene carbonate) (PEG-PTMC) that change their morphology and surface charge when exposed to tumor environment conditions. Well-defined, drug-loaded nanovectors were prepared via direct hydration using liquid oligo(ethylene glycol) as a dispersant. Systematic introduction of basic imidazole-functional TMC derivatives, through modular polymerization, resulted in polymers that self-assembled in multilamellar nanoparticles (at neutral pH) and that were loaded with hydrophobic drugs...
November 20, 2018: ACS Macro Letters
Ruben M F Tomás, Benjamin Martyn, Trisha L Bailey, Matthew I Gibson
Re-engineering mammalian cell surfaces enables modulation of their phenotype, function, and interactions with external markers and may find application in cell-based therapies. Here we use metabolic glycan labeling to install azido groups onto the cell surface, which can act as anchor points to enable rapid, simple, and robust "click" functionalization by the addition of a polymer bearing orthogonally reactive functionality. Using this strategy, new cell surface functionality was introduced by using telechelic polymers with fluorescence or biotin termini, demonstrating that recruitment of biomacromolecules is possible...
November 20, 2018: ACS Macro Letters
Anton H Hofman, Ivan Terzic, Marc C A Stuart, Gerrit Ten Brinke, Katja Loos
Involving supramolecular chemistry in self-assembling block copolymer systems enables design of macromolecular architectures that are challenging to obtain through conventional all-covalent routes. In this work we present supramolecular double-comb triblock terpolymers in which both outer blocks are able to interact with a surfactant via hydrogen bonding and thereby form a comb-shaped architecture upon complexation. While the neat triblock terpolymer only formed a triple lamellar morphology, multiple hierarchical structures were observed in these supramolecular comb-coil-comb triblock terpolymers by simply adjusting the surfactant concentration...
October 16, 2018: ACS Macro Letters
Jingling Zhang, Guofang Li, Nicole S Sampson
We previously reported that cyclohexene and bicyclo[4.2.0]oct-1(8)-ene-8-carboxamides undergo efficient ruthenium-catalyzed alternating ring-opening metathesis polymerization (AROMP). Here, we demonstrate that cyclodecene and cyclododecene also function as cycloalkene monomers in the bicyclo[4.2.0]oct-1(8)-ene-8-carboxamide AROMP system, thus enabling the synthesis of linear alternating copolymers with spacers of different lengths, as demonstrated by means of NMR spectroscopy and gel permeation chromatography...
September 18, 2018: ACS Macro Letters
Pezhman Mohammadi, Grégory Beaune, Bjørn Torger Stokke, Jaakko V I Timonen, Markus B Linder
Liquid-liquid phase separation of biomacromolecules plays a critical role in many of their functions, both as cellular components and in structural assembly. Phase separation is also a key mechanism in the assembly of engineered recombinant proteins for the general aim to build new materials with unique structures and properties. Here the phase separation process of an engineered protein with a block-architecture was studied. As a central block, we used a modified spider silk sequence, predicted to be unstructured...
September 18, 2018: ACS Macro Letters
Lindsay N Woodard, Melissa A Grunlan
Strategies to refine the degradation behavior of polyester biomaterials, particularly to overcome the limitations of slow hydrolytic degradation, would broaden their utility. Herein, we examine the complexities of polyester degradation behavior, its assessment and strategies for refinement. The factors governing polyester degradation are strikingly complex. In addition to the half-life of the hydrolytically-labile bond, a series of interdependent material properties must be considered. Thus, methods used to characterize such material properties, both before and during degradation, must be carefully selected...
August 21, 2018: ACS Macro Letters
Niels L Meereboer, Ivan Terzić, Sarah Saidi, Daniel Hermida Merino, Katja Loos
The electroactive properties of poly(vinylidene fluoride) (PVDF) are a direct consequence of its crystalline phases. Although poorly understood, nanostructuring PVDF in confined geometries can drastically change its crystallization behavior. Therefore, we synthesized a variety of PVDF-based triblock copolymers to gain a better understanding of the melt crystallization and explore how crystallization is affected by the morphology and chemical nature of the amorphous block. Differential scanning calorimetry, small-/wide-angle X-ray scattering, and transmission electron microscopy gave us excellent insights into the morphology and the corresponding crystalline phases...
July 17, 2018: ACS Macro Letters
Jordan C Theriot, Garret M Miyake, Cyrille A Boyer
N,N -Diaryl dihydrophenazines are employed as organic photoredox catalysts (PCs) for photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization. The ability of these PCs to mediate PET-RAFT is heavily dependent on the ability of the PC to access a photoexcited intramolecular charge transfer state. The use of PCs displaying intramolecular charge transfer in the excited state allows for efficient PET-RAFT of a variety of monomers, including vinyl acetate, and in a wide range of solvents...
June 19, 2018: ACS Macro Letters
Anindita Das, Katja Petkau-Milroy, Gilian Klerks, Bas van Genabeek, René P M Lafleur, Anja R A Palmans, E W Meijer
Intriguingly, little is known about the impact of dispersity on the crystallization driven self-assembly (CDSA) of amphiphilic block copolymers in aqueous media. Here, we investigate the influence of dispersity on the CDSA of ABA-type amphiphilic block co-oligomers (ABCOs). Two pairs of ABCOs are synthesized comprising discrete ( Đ = 1.00) or disperse ( Đ = 1.20) isotactic l-lactic acid 16-mers as the semicrystalline hydrophobic block and either oligo(ethylene glycol) methyl ether (MeOoEG) or oligo(tetraethylene glycol succinate) (oTEGSuc) as the discrete hydrophilic block...
May 15, 2018: ACS Macro Letters
Hung V-T Nguyen, Nolan M Gallagher, Farrukh Vohidov, Yivan Jiang, Ken Kawamoto, Hui Zhang, Jiwon V Park, Zhihao Huang, M Francesca Ottaviani, Andrzej Rajca, Jeremiah A Johnson
The polymerization of functional monomers provides direct access to functional polymers without need for postpolymerization modification; however, monomer synthesis can become a bottleneck of this approach. New methods that enable rapid installation of functionality into monomers for living polymerization are valuable. Here, we report the three-step convergent synthesis (two-step longest linear sequence) of a divalent exo -norbornene imide capable of efficient coupling with various nucleophiles and azides to produce diversely functionalized branched macromonomers optimized for ring-opening metathesis polymerization (ROMP)...
April 17, 2018: ACS Macro Letters
Kathryn M Mansfield, Heather D Maynard
Insulin is an important therapeutic protein for the treatment of diabetes, but it is unstable and aggregates upon exposure to environmental stressors encountered during storage and transport. To prevent degradation of the protein in this manner and retain as much in vivo bioactivity as possible, a well-defined insulin-trehalose glycopolymer conjugate was synthesized. To accomplish this, a strategy was employed to site-specifically modify insulin with a polymerization initiator at a particular conjugation site; this also facilitated purification and characterization...
March 20, 2018: ACS Macro Letters
Antti Korpi, Chao Ma, Kai Liu, Nonappa, Andreas Herrmann, Olli Ikkala, Mauri A Kostiainen
Self-assembly is a convenient process to arrange complex biomolecules into large hierarchically ordered structures. Electrostatic attraction between the building blocks is a particularly interesting driving force for the assembly process, as it is easily tunable and reversible. Large biomolecules with high surface charge density, such as proteins and protein cages, are very promising building blocks due to their uniform size and shape. Assemblies of functional molecules with well-defined nanostructures have wide-ranging applications but are difficult to produce precisely by synthetic methods...
March 20, 2018: ACS Macro Letters
Mikko Poutanen, Zafar Ahmed, Lauri Rautkari, Olli Ikkala, Arri Priimagi
Photoisomerization of azobenzene derivatives is a versatile tool for devising light-responsive materials for a broad range of applications in photonics, robotics, microfabrication, and biomaterials science. Some applications rely on fast isomerization kinetics, while for others, bistable azobenzenes are preferred. However, solid-state materials where the isomerization kinetics depends on the environmental conditions have been largely overlooked. Herein, an approach to utilize the environmental sensitivity of isomerization kinetics is developed...
March 20, 2018: ACS Macro Letters
Sangho Won, Steven Hindmarsh, Matthew I Gibson
Carbohydrate-carbohydrate interactions are proposed to be biologically significant but have lower affinities than the well-studied carbohydrate-protein interactions. Here we introduce multivalent glyconanostructures where the surface expression of lactose can be triggered by an external stimulus, and a gold nanoparticle core enables colorimetric signal outputs to probe binding. Macromolecular engineering of a responsive polymer "gate" enables the lactose moieties to be presented only when an external stimulus is present, mimicking how nature uses enzymes to dynamically regulate glycan expression...
February 20, 2018: ACS Macro Letters
Liye Fu, Antonina Simakova, Marco Fantin, Yi Wang, Krzysztof Matyjaszewski
An iron porphyrin catalyst, derived from the active center of proteins such as horseradish peroxidase and hemoglobin, was successfully used for the atom transfer radical polymerizations (ATRP) of methacrylic acid. ATRP of methacrylic acid and other acidic monomers is challenging due to Cu complexation by carboxylates, protonation of the ligand, and displacement of the halogen chain end. A robust mesohemin-based catalyst provided controlled ATRP of methacrylic acid, yielding poly(methacrylic acid) with M n ≥ 20000 and dispersity Đ < 1...
January 16, 2018: ACS Macro Letters
Hsiao-Ping Hsu, Kurt Kremer
Polymer material properties are strongly affected by entanglement effects. For long polymer chains and composite materials, they are expected to be at the origin of many technically important phenomena, such as shear thinning or the Mullins effect, which microscopically can be related to topological constraints between chains. Starting from fully equilibrated highly entangled polymer melts, we investigate the effect of isochoric elongation on the entanglement structure and force distribution of such systems...
January 16, 2018: ACS Macro Letters
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