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ACS Macro Letters

Jingwei Fan, Yannick P Borguet, Lu Su, Tan P Nguyen, Hai Wang, Xun He, Jiong Zou, Karen L Wooley
Well-defined molecular brushes bearing polypeptides as side chains were prepared by a "grafting through" synthetic strategy with two-dimensional control over the brush molecular architectures. By integrating N-carboxyanhydride ring-opening polymerizations (NCA ROPs) and ring-opening metathesis polymerizations (ROMPs), desirable segment lengths of polypeptide side chains and polynorbornene brush backbones were independently constructed in controlled manners. The N2 flow accelerated NCA ROP was utilized to prepare polypeptide macromonomers with different lengths initiated from a norbornene-based primary amine, and those macromonomers were then polymerized via ROMP...
September 19, 2017: ACS Macro Letters
Bas van Genabeek, Bas F M de Waal, Bianca Ligt, Anja R A Palmans, E W Meijer
An experimental study is presented in which we compare the bulk phase behavior of discrete and (partially) disperse diblock co-oligomers (BCOs) with high χ-low N. To this end, oligomers of dimethylsiloxane (oDMS) and lactic acid (oLA) were synthesized, each having either a discrete number of repeat units or a variable block length. Ligation of the blocks resulted in oDMS-oLA BCOs with dispersities ranging from <1.00001 to 1.09, as revealed by mass spectroscopy and size exclusion chromatography. The phase behavior of all BCOs was investigated by differential scanning calorimetry and small-angle X-ray scattering...
July 18, 2017: ACS Macro Letters
Aitziber Iturmendi, Uwe Monkowius, Ian Teasdale
Oxidation responsive polymers with triggered degradation pathways have been prepared via attachment of self-immolative moieties onto a hydrolytically unstable polyphosphazene backbone. After controlled main-chain growth, postpolymerization functionalization allows the preparation of hydrolytically stable poly(organo)phosphazenes decorated with a phenylboronic ester caging group. In oxidative environments, triggered cleavage of the caging group is followed by self-immolation, exposing the unstable glycine-substituted polyphosphazene which subsequently undergoes to backbone degradation to low-molecular weight molecules...
February 21, 2017: ACS Macro Letters
Nicolas R Ball-Jones, Grant W Fahnhorst, Thomas R Hoye
A short and efficient synthesis of a series of isoprenecarboxylic acid esters (ICAEs) and their corresponding polymers is presented. The base-catalyzed eliminative ring-opening of anhydromevalonolactone (3) provides isoprenecarboxylic acid (6-H), which was further transformed to the ICAEs. Reversible addition-fragmentation chain-transfer (RAFT) polymerization was used to synthesize high molecular weight (>100 kg mol(-1)) poly(isoprenecarboxylates) with dispersities (Đ) of ca. 1.5. The glass transition temperatures (Tg) and entanglement molecular weights (Me) of the poly(isoprenecarboxylates) were determined and showed similar trends to the Tg and Me values for analogous poly(acrylate esters)...
October 18, 2016: ACS Macro Letters
Zhen Li, Liang Sun, Yufei Zhang, Andrew P Dove, Rachel K O'Reilly, Guosong Chen
The shells of various poly(dl-lactide)-b-poly(acrylic acid) (PDLLA-b-PAA) spherical micelles and poly(l-lactide)-b-poly(acrylic acid) (PLLA-b-PAA) cylindrical micelles were functionalized with mannose to yield glyco-nanoparticles (GNPs) with different shapes and dimensions. All of these GNPs were shown to have good biocompatibility (up to 1 mg/mL). Cellular uptake experiments using RAW 264.7 have shown that the spherical GNPs were internalized to a much greater extent than the cylindrical GNPs and such a phenomenon was attributed to their different endocytosis pathways...
September 20, 2016: ACS Macro Letters
X Chelsea Chen, Hee Jeung Oh, Jay F Yu, Jeffrey K Yang, Nikos Petzetakis, Anand S Patel, Steven W Hetts, Nitash P Balsara
We introduce the use of block copolymer membranes for an emerging application, "drug capture". The polymer is incorporated in a new class of biomedical devices, referred to as ChemoFilter, which is an image-guided temporarily deployable endovascular device designed to increase the efficacy of chemotherapy-based cancer treatment. We show that block copolymer membranes consisting of functional sulfonated polystyrene end blocks and a structural polyethylene middle block (S-SES) are capable of capturing doxorubicin, a chemotherapy drug...
August 16, 2016: ACS Macro Letters
Kaushlendra Kumar, Eduard Jimenez Castaño, Andrew R Weidner, Adem Yildirim, Andrew P Goodwin
Interest in stimulus responsive materials and polymers has grown over the years, having shown great promise in a diverse set of applications. For drug delivery, stimulus-responsive polymers have been shown to encapsulate therapeutic cargo such as small molecule drugs or proteins, deliver them to specific locations in the body, and release them so that they can induce a therapeutic effect in the patient. Most hydrolytically degradable polymers are synthesized via nucleophilic, anionic, or cationic polymerization, which generally requires protection of nucleophilic or protic side chains prior to polymerization...
May 17, 2016: ACS Macro Letters
Angela L Holmberg, Kaleigh H Reno, Ngoc A Nguyen, Richard P Wool, Thomas H Epps
As viable precursors to a diverse array of macromolecules, biomass-derived compounds must impart wide-ranging and precisely controllable properties to polymers. Herein, we report the synthesis and subsequent reversible addition-fragmentation chain-transfer polymerization of a new monomer, syringyl methacrylate (SM, 2,6-dimethoxyphenyl methacrylate), that can facilitate widespread property manipulations in macromolecules. Homopolymers and heteropolymers synthesized from SM and related monomers have broadly tunable and highly controllable glass transition temperatures ranging from 114 to 205 °C and zero-shear viscosities ranging from ∼0...
May 17, 2016: ACS Macro Letters
Fei Yu, Ying Xie, Yan Wang, Zheng-Hong Peng, Jing Li, David Oupický
Chloroquine-containing HPMA copolymers (pCQs) were synthesized for the first time by copolymerization of methacryloylated hydroxychloroquine and HPMA. The copolymers showed lower cytotoxicity when compared with hydroxychloroquine. Treatment of cancer cells with pCQ resulted in decreased surface expression of chemokine receptor CXCR4. The pCQ copolymers showed effective inhibition of CXCR4/SDF1-mediated cancer cell migration that was fully comparable with a commercial small-molecule CXCR4 antagonist AMD3100...
March 15, 2016: ACS Macro Letters
Yin Ning, Lee A Fielding, Kay E B Doncom, Nicholas J W Penfold, Alexander N Kulak, Hideki Matsuoka, Steven P Armes
New spherical diblock copolymer nanoparticles were synthesized via RAFT aqueous dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA) at 70 °C and 20% w/w solids using either poly(carboxybetaine methacrylate) or poly(proline methacrylate) as the steric stabilizer block. Both of these stabilizers contain carboxylic acid groups, but poly(proline methacrylate) is anionic above pH 9.2, whereas poly(carboxybetaine methacrylate) has zwitterionic character at this pH. When calcite crystals are grown at an initial pH of 9...
March 15, 2016: ACS Macro Letters
Xinpeng Zhang, Weixian Xi, Chen Wang, Maciej Podgórski, Christopher N Bowman
An efficient visible-light-sensitive photobase generator for thiol-Michael addition reactions was synthesized and evaluated. This highly reactive catalyst was designed by protecting a strong base (tetramethyl guanidine, TMG) with a visible-light-responsive group which was a coumarin derivative. The coumarin-coupled TMG was shown to exhibit extraordinary catalytic activity toward initiation of the thiol-Michael reaction, including thiol-Michael addition-based polymerization, upon visible-light irradiation, leading to a stoichiometric reaction of both thiol and vinyl functional groups...
February 16, 2016: ACS Macro Letters
Nerea Casado, Guiomar Hernández, Antonio Veloso, Shanmukaraj Devaraj, David Mecerreyes, Michel Armand
The development of new redox polymers is being boosted by the increasing interest in the area of energy and health. The development of new polymers is needed to further advance new applications or improve the performance of actual devices such as batteries, supercapacitors, or drug delivery systems. Here we show the synthesis and characterization of a new polymer which combines the present most successful conjugated polymer backbone and the most successful redox active side group, i.e., poly(3,4-ethylenedioxythiophene) (PEDOT), and a nitroxide stable radical...
January 19, 2016: ACS Macro Letters
Franziska Dorner, David Boschert, Alexandra Schneider, Wibke Hartleb, Ali Al-Ahmad, Karen Lienkamp
Regeneration of functional polymer surfaces after damage or contamination is an unresolved scientific challenge, and also of practical importance. In this proof-of-concept study, we present a method to regenerate a functional surface property using a polymer multi-layer architecture. This is exemplified using antimicrobially active surfaces. The idea is to shed the top layer of the polymer layer stack, like a reptile shedding its skin. The proof-of-concept stack consists of two antimicrobial layers and a degradable interlayer...
December 15, 2015: ACS Macro Letters
Matthew S Menyo, Craig J Hawker, J Herbert Waite
Four-arm poly(ethylene glycol) (PEG) star polymers modified with 3-hydroxy-4-pyridinone (HOPO) end groups were shown to form transient, coordination networks upon addition of trivalent cations In(3+), Fe(3+), and Al(3+). These coordination-based hydrogels exhibited high activation energies of viscoelasticity (34 kT) and characteristic bond lifetimes tunable over 2 orders of magnitude and could be incorporated into poly(hydroxyethylacrylamide)-based covalent scaffolds to create interpenetrating network hydrogels...
November 17, 2015: ACS Macro Letters
Jun Zhao, John Qiao, Min Zhou, Sanjay Gupta, Chun Li, Marites P Melancon
Irreversible electroporation (IRE) is a novel non-thermal ablative treatment for cancer patients with unresectable tumor. IRE kills tumor cells by applying a strong electric field across the cell membrane, thereby creating irreparable pores. Compared to conventional thermal ablation, IRE is effective in perivascular tissues and can preserve the surrounding sensitive structures. However, tumor cells may survive in the regions exposed to insufficient electric field strength, and cause tumor relapse afterwards...
October 20, 2015: ACS Macro Letters
T Gaillard, C Poulard, T Voisin, C Honorez, P Davidson, W Drenckhan, M Roché
Thin polymer films have attracted attention because of both their broad range of applications and of the fundamental questions they raise regarding the dynamic response of confined polymers. These films are unstable if the temperature is above their glass transition temperature T g. Here, we describe freestanding thin films of centimetric dimensions made of a comb copolymer melt far from its glass transition that are stable for more than a day. These long lifetimes allowed us to characterize the drainage dynamics and the thickness profile of the films...
October 20, 2015: ACS Macro Letters
Kaushlendra Kumar, Andrew P Goodwin
This work describes the depolymerization of poly(vinyl acetate-alt-sulfur dioxide) (PVAS) as initiated by chemical and mechanical stimuli. In recent years, macromolecules that are able to depolymerize in response to specific stimuli have been highly sought because of their ability to amplify signal for sensing and drug delivery. Examples include self-immolative polymers from alkoxyphenol derivatives and polyaldehydes. We show here that alternating copolymers of sulfur dioxide and vinyl acetate are able to undergo similar depolymerization into their monomer components in response to various chemical and mechanical stimuli...
September 15, 2015: ACS Macro Letters
Hua Wei, Christine E Wang, Nicholas Tan, Andrew J Boydston, Suzie H Pun
Polymers with advanced architectures can now be readily and reproducibly synthesized using controlled living polymerization. These materials are attractive as potential drug carriers due to their tunable size, versatile methods of drug incorporation and release, and ease of functionalization with targeting ligands. In this work, we report the design and development of macrocyclic brush, or "sunflower," polymers, synthesized by controlled radical polymerization of hydrophilic "petals" from a cyclic multimacroinitiator "core...
September 15, 2015: ACS Macro Letters
Tyler S Stukenbroeker, Jeff S Bandar, Xiangyi Zhang, Tristan H Lambert, Robert M Waymouth
Cyclopropenimine superbases were employed to catalyze the ring-opening polymerization of lactide. Polymerization occurred readily in the presence and absence of alcohol initiators. Polymerizations in the absence of alcohol initiators revealed a competitive initiation mechanism involving deprotonation of lactide by the cyclopropenimine to generate an enolate. NMR and MALDI-TOF analysis of the poly(lactides) generated from cyclopropenimines in the absence of alcohol initiators showed acylated lactide and hydroxyl endgroups...
August 18, 2015: ACS Macro Letters
Damini Gupta, Jeremy J Miller, Abhiram Muralidhar, Sara Mahshid, Walter Reisner, Kevin D Dorfman
We present experimental demonstration that weak excluded volume effects arise in DNA nanochannel confinement. In particular, by performing measurements of the variance in chain extension as a function of nanochannel dimension for effective channel size ranging from 305 nm to 453 nm, we show that the scaling of the variance in extension with channel size rejects the de Gennes scaling δ (2) X ~ D (1/3) in favor of δ (2) X ~ D (0) using uncertainty at the 95% confidence level. We also show how simulations and confinement spectroscopy can be combined to reduce molecular weight dispersity effects arising from shearing, photocleavage, and nonuniform staining of DNA...
July 2015: ACS Macro Letters
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