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Polyacrylate acid

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https://www.readbyqxmd.com/read/28530283/composite-cd-mof-nanocrystals-containing-microspheres-for-sustained-drug-delivery
#1
Haiyan Li, Nana Lv, Xue Li, Botao Liu, Jing Feng, Xiaohong Ren, Tao Guo, Dawei Chen, J Fraser Stoddart, Ruxandra Gref, Jiwen Zhang
Metal-organic frameworks (MOFs), which are typically embedded in polymer matrices as composites, are emerging as a new class of carriers for sustained drug delivery. Most of the MOFs and the polymers used so far in these composites, however, are not pharmaceutically acceptable. In the investigation reported herein, composites of γ-cyclodextrin (γ-CD)-based MOFs (CD-MOFs) and polyacrylic acid (PAA) were prepared by a solid in oil-in-oil (s/o/o) emulsifying solvent evaporation method. A modified hydrothermal protocol has been established which produces efficiently at 50 °C in 6 h micron (5-10 μm) and nanometer (500-700 nm) diameter CD-MOF particles of uniform size with smooth surfaces and powder X-ray diffraction patterns that are identical with those reported in the literature...
May 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28508632/colloidally-assembled-zinc-ferrite-magnetic-beads-superparamagnetic-labels-with-high-magnetic-moments-for-mr-sensors
#2
Jooneon Park, Marc D Porter, Michael C Granger
Magnetic particles are widely used as labels in magnetoresistive (MR) sensors. To use magnetic particles as labels, several important characteristics should be considered, such as superparamagnetism, a high magnetic moment per particle (m), facile surface functionalization and biomolecule immobilization, colloidal stability, and analyte specificity. Described in this paper is the preparation of magnetic labels with a high m using colloidal assemblies of superparamagnetic zinc ferrite nanoparticles (ZFNPs, ~9 nm)...
May 16, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28506935/retrosynthesis-of-caco3-via-amorphous-precursor-particles-using-gastroliths-of-the-red-claw-lobster-cherax-quadricarinatus
#3
Andrónico Neira-Carrillo, María Soledad Fernández, Gonzalo Poblete Hevia, José Luis Arias, Denis Gebauer, Helmut Cölfen
Gastroliths are highly calcified structures formed in the cardiac stomach wall of crustaceans for the temporary storage of amorphous CaCO3 (ACC). The gastrolithic ACC is stabilized by the presence of biomolecules, and represents a novel model for research into biomineralization. For the first time, an in vitro biomimetic retrosynthesis of scaffolds of gastrolithic matrices with CaCO3 is presented. With the help of synthetic polyacrylic (PAA) and phytic (PA) acids, amorphous precursor particles were stabilized in double (DD) and gas (GD) diffusion crystallization assays...
May 12, 2017: Journal of Structural Biology
https://www.readbyqxmd.com/read/28499631/extrafibrillar-collagen-demineralization-based-chelate-and-rinse-technique-bridges-the-gap-between-wet-and-dry-dentin-bonding
#4
Sui Mai, Chin-Chuan Wei, Li-Sha Gu, Fu-Cong Tian, Dwayne D Arola, Ji-Hua Chen, Yang Jiao, David H Pashley, Li-Na Niu, Franklin R Tay
Limitations associated with wet-bonding led to the recent development of a selective demineralization strategy in which dentin was etched with a reduced concentration of phosphoric acid to create exclusive extrafibrillar demineralization of the collagen matrix. However, the use of acidic conditioners removes calcium via diffusion of very small hydronium ions into the intrafibrillar collagen water compartments. This defeats the purpose of limiting the conditioner to the extrafibrillar space to create a collagen matrix containing only intrafibrillar minerals to prevent collapse of the collagen matrix...
May 9, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28494246/catalytic-hydrodechlorination-of-triclosan-using-a-new-class-of-anion-exchange-resin-supported-palladium-catalysts
#5
Bing Han, Wen Liu, Jingwen Li, Jin Wang, Dongye Zhao, Rui Xu, Zhang Lin
We prepared a new class of anion-exchange-resin supported Pd catalysts for efficient hydrodechlorination of triclosan in water. The catalysts were prepared through an initial ion-exchange uptake of PdCl4(2-) and subsequent reduction of Pd(II) to Pd(0) nanoparticles at ambient temperature. Two standard strong-base anion exchange resins (IRA-900 and IRA-958) with different matrices (polystyrene and polyacrylic) were chosen as the supports. SEM and TEM images showed that Pd(0) nanoparticles were evenly attached on the resin surface with a mean size of 3-5 nm...
April 26, 2017: Water Research
https://www.readbyqxmd.com/read/28470061/sunlight-induced-preparation-of-functionalized-gold-nanoparticles-as-recyclable-colorimetric-dual-sensor-for-aluminum-and-fluoride-in-water
#6
Anshu Kumar, Madhuri Bhatt, Gaurav Vyas, Shreya Bhatt, Parimal Paul
A sunlight induced simple green route has been developed for the synthesis of polyacrylate functionalized gold nanoparticles (PAA-AuNPs), in which poly(acrylic acid) functions as a reducing as well as stabilizing agent. This material has been characterized on the basis of spectroscopic and microscopic studies; it exhibited selective colorimetric detection of Al(3+) in aqueous media, and the Al(3+) induced aggregated PAA-AuNPs exhibited detection of F(-) with sharp color change and high selectivity and sensitivity out of a large number of metal ions and anions tested...
May 15, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28467592/-effect-of-silver-nanoparticles-on-anaerobic-bacteria
#7
Renata Večeřová, Aleš Panáček, Milan Kolář
OBJECTIVE: The aim was to evaluate the antibacterial effect of silver nanoparticles on anaerobic bacteria. MATERIAL AND METHODS: The microdilution method was used to determine the minimum inhibitory concentrations (MICs) of 28 nm silver nanoparticles, both unstabilized and stabilized by casein, gelatin and polyacrylic acid. The following anaerobic bacteria were tested: Bacteroides fragilis, Bacteroides thetaiotaomicron, Eggerthella lenta, Propionibacterium acnes, Clostridium perfringens, Clostridium difficile and Fusobacterium varium...
March 2017: Klinická Mikrobiologie a Infekc̆ní Lékar̆ství
https://www.readbyqxmd.com/read/28457430/synthesis-of-cellulose-based-double-network-hydrogels-demonstrating-high-strength-self-healing-and-antibacterial-properties
#8
Yixi Wang, Zhicun Wang, Keliang Wu, Jianning Wu, Guihua Meng, Zhiyong Liu, Xuhong Guo
Novel antibacterial double-network (DN) hydrogels with superior mechanical and self-healing properties are developed via the UV-initiated copolymerization of polyacrylic acid (PAA)-grafted quaternized cellulose (QCE) and polyvinyl alcohol (PVA). The QCE functioned as an antibacterial agent, resulting in excellent antibacterial capability (antibacterial rate >93%). The hydrogels are thus protected from microbial attack in natural environments, prolonging their lifetime. The PVA functioned as a physical cross-linker, resulting in superior mechanical properties...
July 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28440385/temporal-viscosity-modulations-driven-by-a-ph-sensitive-polymer-coupled-to-a-ph-changing-chemical-reaction
#9
D M Escala, A P Muñuzuri, A De Wit, J Carballido-Landeira
The Formaldehyde-Sulfite (FS) and the Formaldehyde-Sulfite-Gluconolactone (FSG) systems are examples of complex chemical reactions accompanied by well-controlled variations in pH. While the FS system exhibits a clock behavior, in the FSG reaction, this mechanism is coupled with the hydrolysis of the gluconolactone which gives the possibility to show large temporal oscillations of pH in an open reactor. In this work, we show how these reactive systems, due to their organic nature, can be coupled with pH sensitive polymers, particularly with polyacrylic acid (PAA) to trigger temporal changes of viscosity...
May 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28432970/insights-into-key-factors-controlling-go-stability-in-natural-surface-waters
#10
Yang Gao, Xuemei Ren, Xiaoli Tan, Tasawar Hayat, Ahmed Alsaedi, Changlun Chen
The effects of pH, cations (Na(+), K(+), Mg(2+), Ca(2+) and Al(3+)), and anions (Cl(-), HCO3(-), HPO4(2-) and SO4(2-)) on graphene oxide (GO) stability were investigated to address the current limitations in the knowledge regarding the stability of GO in natural surface water and its underlying mechanism. The threshold values of cations that destabilize GO were obtained and affected by both pH and anions. By employing elemental mapping and studying the effects of polyacrylic acid (PAA) on GO sedimentation and the re-dispersion of GO aggregates, we find that the GO aggregates induced by Na(+) and K(+) via electric double layer suppression and by Ca(2+) and Al(3+) via strong complxing are difficult to re-disperse completely...
April 11, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28427665/combined-ultrasonic-and-gamma-irradiation-to-prepare-tio2-pet-g-paac-fabric-composite-for-self-cleaning-application
#11
Mohamed Mohamady Ghobashy
The grafting of polyacrylic acid (PAAc) onto the fabric of Poly(ethyleneterephthalate) (PET) was loaded with TiO2 by a mixture sonication of TiO2 dispersed in AAc dissolved in acetone solvent. Ultrasonic irradiation was utilized as a tool for a good dispersion of TiO2 onto the PET fabric. The grafted PET fabrics with acrylic acid AAc monomer were successfully obtained using gamma-ray induced graft polymerization, the degree of grafting PET-g-PAAc fiber was 105%. The chemical compositions and crystal structure of grafted TiO2@PET-g-PAAc fabrics were characterized by ATR-FTIR and XRD...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28419800/ph-reversible-encapsulation-of-oppositely-charged-colloids-mediated-by-polyelectrolytes
#12
Yong Guo, Bas G P van Ravensteijn, Chris H J Evers, Willem K Kegel
We report the first example of reversible encapsulation of micron-sized particles by oppositely charged submicron smaller colloids. The reversibility of this encapsulation process is regulated by pH-responsive poly(acrylic acid) (PAA) present in solution. The competitive adsorption between the small colloids and the poly(acrylic acid) on the surface of the large colloids plays a key role in the encapsulation behavior of the system. pH offers an experimental knob to tune the electrostatic interactions between the two oppositely charged particle species via regulation of the charge density of the poly(acrylic acid)...
May 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28411637/armored-enzyme-nanohybrids-and-their-catalytic-function-under-challenging-conditions
#13
Omkar V Zore, Rajeswari M Kasi, Challa V Kumar
Synthesis and characterization of highly stable and functional bienzyme-polymer triads assembled on layered graphene oxide (GO) are described here. Glucose oxidase (GOx) and horseradish peroxidase (HRP) were used as model enzymes and polyacrylic acid (PAA) as model polymer to armor the enzymes. PAA-armored GOx and HRP covalent conjugates were further protected from denaturation by adsorption onto GO nanosheets. Structure and morphology of this enzyme-polymer-nanosheet hybrid biocatalyst (GOx-HRP-PAA/GO) were confirmed by agarose gel electrophoresis, zeta potential, circular dichroism, and transmission electron microscopy...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28371515/spherical-polyelectrolyte-brushes-as-a-novel-platform-for-paramagnetic-relaxation-enhancement-and-passive-tumor-targeting
#14
Qin Zhu, Zhenyu Yuan, Weiqiao Qian, Yuanyuan Li, Zhiqiang Qiu, Weijun Tang, Jie Wang, Yun Ding, Aiguo Hu
A novel platform for the development of highly efficient magnetic resonance imaging (MRI) contrast agents has been demonstrated. New contrast agents are designed and produced through electrostatic self-assembly of cationic gadolinium(III) complexes onto anionic spherical polyelectrolyte brushes (SPB). The structurally well-defined SPB are composed of polystyrene core and polyacrylic acid brush layer, where numerous binding sites and confined microenvironments are available for the embedment of the gadolinium(III) contrast agents...
April 3, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28368667/one-step-formation-of-lipid-polyacrylic-acid-calcium-carbonate-nanoparticles-for-co-delivery-of-doxorubicin-and-curcumin
#15
Jianqing Peng, Shintaro Fumoto, Hirotaka Miyamoto, Yi Chen, Naotaka Kuroda, Koyo Nishida
A doxorubicin (Dox) and curcumin (Cur) combination treatment regimen has been widely studied in pre-clinical research. However, the nanoparticles developed for this combination therapy require a consecutive drug loading process because of the different water-solubility of these drugs. The present study provides a strategy for the 'one-step' formation of nanoparticles encapsulating both Dox and Cur. We took advantage of polyacrylic acid (PAA) and calcium carbonate (CaCO3) to realise a high drug entrapment efficiency and pH-sensitive drug release using a simplified preparation method...
April 3, 2017: Journal of Drug Targeting
https://www.readbyqxmd.com/read/28358160/highly-stiff-yet-elastic-microcapsules-incorporating-cellulose-nanofibrils
#16
Gilad Kaufman, Shomeek Mukhopadhyay, Yekaterina Rokhlenko, Siamak Nejati, Rostislav Boltyanskiy, Youngwoo Choo, Michael Loewenberg, Chinedum O Osuji
Microcapsules with high mechanical stability and elasticity are desirable in a variety of contexts. We report a single-step method to fabricate such microcapsules by microfluidic interfacial complexation between high stiffness cellulose nanofibrils (CNF) and an oil-soluble cationic random copolymer. Single-capsule compression measurements reveal an elastic modulus of 53 MPa for the CNF-based capsule shell with complete recovery of deformation from strains as large as 19%. We demonstrate the ability to manipulate the shell modulus by the use of polyacrylic acid (PAA) as a binder material, and observe a direct relationship between the shell modulus and the PAA concentration, with moduli as large as 0...
April 12, 2017: Soft Matter
https://www.readbyqxmd.com/read/28350963/gd-dots-with-strong-ligand-water-interaction-for-ultrasensitive-magnetic-resonance-renography
#17
Xiao-Yu Zheng, Kai Zhao, Jinglong Tang, Xin-Yu Wang, Lin-Dong Li, Nai-Xiu Chen, Yan-Jie Wang, Shuo Shi, Xiaodong Zhang, Sivakumar Malaisamy, Ling-Dong Sun, Xiaoying Wang, Chunying Chen, Chun-Hua Yan
Magnetic resonance imaging contrast agents with both significantly enhanced relaxivity and minimal safety risk are of great importance for sensitive clinical diagnosis, but have rarely been reported. Herein, we present a simple strategy to improve relaxivity by introducing surface ligands with strong interaction to water molecules. As a proof of concept, NaGdF4 nanoparticles (NPs) capped by poly(acrylic acid) (PAA) show superior relaxivity to those capped by polyethylenimine and polyethylene glycol, which is attributed to the strong hydrogen-bond capacity of PAA to water molecules as revealed by theoretical calculation...
April 25, 2017: ACS Nano
https://www.readbyqxmd.com/read/28345148/fast-self-healing-of-polyelectrolyte-multilayer-nanocoating-and-restoration-of-super-oxygen-barrier
#18
Yixuan Song, Kevin P Meyers, Joseph Gerringer, Ramesh K Ramakrishnan, Mohammad Humood, Shuang Qin, Andreas A Polycarpou, Sergei Nazarenko, Jaime C Grunlan
A self-healable gas barrier nanocoating, which is fabricated by alternate deposition of polyethyleneimine (PEI) and polyacrylic acid (PAA) polyelectrolytes, is demonstrated in this study. This multilayer film, with high elastic modulus, high glass transition temperature, and small free volume, has been shown to be a super oxygen gas barrier. An 8-bilayer PEI/PAA multilayer assembly (≈700 nm thick) exhibits an oxygen transmission rate (OTR) undetectable to commercial instrumentation (<0.005 cc (m(-2) d(-1) atm(-1) ))...
March 27, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28327587/in-situ-characterization-of-the-initial-effect-of-water-on-molecular-interactions-at-the-interface-of-organic-inorganic-hybrid-systems
#19
Sven Pletincx, Lena Trotochaud, Laura-Lynn Fockaert, Johannes M C Mol, Ashley R Head, Osman Karslıoğlu, Hendrik Bluhm, Herman Terryn, Tom Hauffman
Probing initial interactions at the interface of hybrid systems under humid conditions has the potential to reveal the local chemical environment at solid/solid interfaces under real-world, technologically relevant conditions. Here, we show that ambient pressure X-ray photoelectron spectroscopy (APXPS) with a conventional X-ray source can be used to study the effects of water exposure on the interaction of a nanometer-thin polyacrylic acid (PAA) layer with a native aluminum oxide surface. The formation of a carboxylate ionic bond at the interface is characterized both with APXPS and in situ attenuated total reflectance Fourier transform infrared spectroscopy in the Kretschmann geometry (ATR-FTIR Kretschmann)...
March 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28322540/rapid-recovery-double-cross-linking-hydrogel-with-stable-mechanical-properties-and-high-resilience-triggered-by-visible-light
#20
Longxiang Zhu, Jianhui Qiu, Eiichi Sakai, Kazushi Ito
The designed tough hydrogels, depending on energy dissipation mechanism, possess excellent biocompatibility, stimuli-responsiveness, and outstanding mechanical properties. However, the application of hydrogels is greatly limited in actuators and sensors for the lack of instantaneous recovery and resilience. In this work, we synthesized a double cross-linking poly(acrylic acid) hydrogel via a simple, one-pot, visible-light-trigger polymerization, with carboxymethyl cellulose as initiator and the first cross-linker, N,N'-methylene bis(acrylamide) (MBA) as the second cross-linker...
April 5, 2017: ACS Applied Materials & Interfaces
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