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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
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
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
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
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
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
Amandine Noel, Yannick P Borguet, Karen L Wooley
A series of hydrolytically degradable fluorescent poly(ferulic acid-co-tyrosine)-g-mPEG graft copolymers were synthesized and shown to undergo self-assembly in aqueous media to yield fluorescent micelles. The polymers and their micellar assemblies exhibited greater fluorescence emission intensity than did their small molecular building blocks, which provides a self-reporting character that has potential for monitoring the polymer integrity and also for performing in theranostics applications. The amphiphilic graft-copolymers were synthesized by Cu-assisted azide-alkyne "click" addition of azido-functionalized mPEG polymers onto fluorescent degradable hydrophobic copolymers displaying randomly distributed alkyne side-chain groups along their biorenewably derived poly(ferulic acid-co-tyrosine) backbones...
June 16, 2015: ACS Macro Letters
William B Hubbard, Margaret M Lashof-Sullivan, Erin B Lavik, Pamela J VandeVord
In response to the lack of therapeutics for internal bleeding following a traumatic event, we synthesized hemostatic dexamethasone nanoparticles (hDNP) to help alleviate internal hemorrhaging. hDNP consist of a block copolymer, poly(lactic-co-glycolic acid)-poly(l-lysine)-poly(ethylene glycol) conjugated to a peptide, glycine-arginine-glycine-aspartic acid-serine (GRGDS). These particles were evaluated as treatment for primary blast lung injury in a rodent model. Animals were randomly placed into test and control groups, exposed to blast and given immediate injection...
April 21, 2015: ACS Macro Letters
Meng-Hsuan Hsiao, Qingxin Mu, Zachary R Stephen, Chen Fang, Miqin Zhang
Nanoparticle (NP) formulations may be used to improve in vivo efficacy of hydrophobic drugs by circumventing solubility issues and providing targeted delivery. In this study, we developed a hexanoyl-chitosan-PEG (CP6C) copolymer coated, paclitaxel (PTX)-loaded, and chlorotoxin (CTX) conjugated iron oxide NP (CTX-PTX-NP) for targeted delivery of PTX to human glioblastoma (GBM) cells. We modified chitosan with polyethylene glycol (PEG) and hexanoyl groups to obtain the amphiphilic CP6C. The resultant copolymer was then coated onto oleic acid-stabilized iron oxide NPs (OA-IONP) via hydrophobic interactions...
April 21, 2015: ACS Macro Letters
Hui Wang, Krishna R Raghupathi, Jiaming Zhuang, S Thayumanavan
We describe a novel activatable probe for fluorine-19 NMR based on self-assembling amphiphilic dendrons. The dendron probe has been designed to be spectroscopically silent due to the formation of large aggregates. Upon exposure to the specific target enzyme, the aggregates disassemble to give rise to a sharp (19)F NMR signal. The probe is capable of detecting enzyme concentrations in the low nanomolar range. Response time of the probe was found to be affected by the hydrophilic-lipophilic balance of dendrons...
April 21, 2015: ACS Macro Letters
Michael Lang, Michael Rubinstein, Jens-Uwe Sommer
Large-scale simulations of the swelling of a long N-mer in a melt of chemically identical P-mers are used to investigate a discrepancy between theory and experiments. Classical theory predicts an increase of probe chain size R ∼ P (-0.18) with decreasing degree of polymerization P of melt chains in the range of 1 < P < N (1/2). However, both experiment and simulation data are more consistent with an apparently slower swelling R ∼ P (-0.1) over a wider range of melt degrees of polymerization. This anomaly is explained by taking into account the recently discovered long-range bond correlations in polymer melts and corrections to excluded volume...
February 17, 2015: ACS Macro Letters
Nikita Oskolkov, Amnon Bar-Shir, Kannie W Y Chan, Xiaolei Song, Peter C M van Zijl, Jeff W M Bulte, Assaf A Gilad, Michael T McMahon
The protamines are a low-molecular-weight, arginine-rich family of nuclear proteins that protect chromosomal DNA in germ cells by packing it densely using electrostatic interactions. Human protamine-1 (hPRM1) has been developed as a magnetic resonance imaging (MRI) chemical exchange saturation transfer (CEST) reporter gene, based on a sequence that is approximately 50% arginine, which has a side chain with rapidly exchanging protons. In this study, we have synthesized hPRM1 and determined how its CEST MRI contrast varies as a function of pH, phosphorylation state, and upon noncovalent interaction with nucleic acids and heparin (as antagonist)...
January 20, 2015: ACS Macro Letters
Julia A Kalow, Timothy M Swager
Architecture represents an underutilized yet promising control element in polymer design due to the challenging synthesis of compositionally varied branched copolymers. We report the one-pot synthesis of miktoarm branched polymers by ring-opening metathesis polymerization. In this work, we graft to and from telechelic poly(3-hexylthiophene), which is end-capped by oxime click chemistry, using various norbornene monomers. The self-assembly of the resulting miktoarm H-shaped conjugated polymers is studied in solution and in the solid state...
2015: ACS Macro Letters
Zheng-Hong Peng, Jindřich Kopeček
A N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-CXCR4 antagonist (BKT140) conjugate (P-BKT140) was developed and its biological activities were tested. Both free BKT140 and monomer MA-GGPLGLAG-BKT140 (MA is methacryloyl) were prepared by solid phase synthesis. P-BKT140 was prepared by reversible addition-fragmentation chain transfer (RAFT) copolymerization of monomers HPMA and MA-GGPLGLAG-BKT140. The in vitro results show that the free BKT140 and P-BKT140 have similar cytotoxicity against human prostate carcinoma PC-3 cells, indicating that conjugation of BKT140 to HPMA did not significantly impact the cytotoxicity of BKT140...
December 16, 2014: ACS Macro Letters
Ryan P Murphy, Elizabeth G Kelley, Simon A Rogers, Millicent O Sullivan, Thomas H Epps
Chain exchange between block polymer micelles in highly selective solvents, such as water, is well-known to be arrested under quiescent conditions, yet this work demonstrates that simple agitation methods can induce rapid chain exchange in these solvents. Aqueous solutions containing either pure poly(butadiene-b-ethylene oxide) or pure poly(butadiene-b-ethylene oxide-d 4) micelles were combined and then subjected to agitation by vortex mixing, concentric cylinder Couette flow, or nitrogen gas sparging. Subsequently, the extent of chain exchange between micelles was quantified using small angle neutron scattering...
November 18, 2014: ACS Macro Letters
Yu Rong, Jiangbo Yu, Xuanjun Zhang, Wei Sun, Fangmao Ye, I-Che Wu, Yong Zhang, Sarah Hayden, Yue Zhang, Changfeng Wu, Daniel T Chiu
Cross-linked polymer dots with intense and narrow yellow emission were designed using boron-dipyrromethene (BODIPY) polymer as the acceptor and poly[9,9-dioctylfluorenyl-2,7-diyl-co-1,4-benzo-{2,1'-3}-thiadiazole] (PFBT) polymer as the donor. The emission fwhm's of the polymer dots (Pdots) were 37 nm. CL-BODIPY 565 Pdots were about 5 times brighter than commercial quantum dots (Qdots) 565 under identical experimental conditions. Specific cellular targeting indicated that the small, bright, and narrow emissive CL-BODIPY 565 Pdots are promising probes for biological applications...
October 21, 2014: ACS Macro Letters
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