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Sample records for polyacrylic acid paa

  1. Comparative study between chitin/polyacrylic acid (PAA) dressing, lipido-colloid absorbent dressing and alginate wound dressing: a pilot study in the treatment of partial-thickness wound.

    PubMed

    Angspatt, Apichai; Tanvatcharaphan, Puttan; Channasanon, Somruethai; Tanodekaew, Siriporn; Chokrungvaranont, Prayuth; Sirimaharaj, Wimol

    2010-06-01

    Polyacrylic acid grafted chitin (Chitin-PAA) contains a hydrogel characteristic that makes it more suitable for wound dressing application. In animal models, Chitin-PAA dressing exhibited properties as a promising dressing. Epithelization promotion, rapid reduction of wound size, reduction of inflammatory cell response, and less toxicity had been noted. Carryout a pilot clinical comparative study of Chitin-PAA dressing, lipido-colloid absorbent dressing, and alginate wound dressing in the treatment of partial-thickness wound. Between June 2006 and March 2007, 36 partial-thickness wounds were randomized into three groups and three different types of dressing were used. Each wound was treated until it was completely healed, and a visual analogue scale was used for the pain evaluation. The present study shows the visual analogue pain score in the Chitin-PAA group seems to be a bit higher than the Urgocell group but not statistically different. The completely healed day is not significantly different. Three patients in the lipido-colloid absorbent dressing groups had wound infection but eventually healed after treatment. There was no statistical difference in terms of visual analogue pain score and healing time between the lipido-colloid absorbent dressing, alginate dressing, and chitin-PAA dressing.

  2. Surface Wave Velocity of Crosslinked Polyacrylate Gels

    NASA Astrophysics Data System (ADS)

    Matsuoka, Tatsuro; Kinouchi, Wataru; ShinobuKoda, ShinobuKoda; Nomura, Hiroyasu

    1999-05-01

    Surface wave velocities of crosslinked polyacrylate hydrogelswere measured as a function of water content with differentcompositions of sodium polyacrylate (NaPA) and polyacrylic acid (PAA).The water content and composition dependencies of the surface wavevelocity were discussed.

  3. Precipitation of biomimetic fluorhydroxyapatite/polyacrylic acid nanostructures

    NASA Astrophysics Data System (ADS)

    Roche, Kevin J.; Stanton, Kenneth T.

    2015-01-01

    Ordered structures of fluorhydroxyapatite (FHA) nanoparticles that resemble the nanostructure of natural human enamel have been prepared. Wet precipitation in the presence of polyacrylic acid (PAA) was used, and the particle morphology was altered by varying several reaction conditions. High molecular weight PAA increased particle length from around 54 nm to several hundred nanometres, while maintaining particle width at 15 nm. PAA concentration and the order of mixing the reactants also influenced crystal morphology. Optimum conditions produced dense, aligned bundles of highly elongated nanorods, which are very similar to the hierarchical nanostructure of human tooth enamel.

  4. Properties of TiO2-polyacrylic acid dispersions with potential for molecular recognition.

    PubMed

    Kanehira, Koki; Banzai, Toshiaki; Ogino, Chiaki; Shimizu, Nobuaki; Kubota, Yoshinobu; Sonezaki, Shuji

    2008-06-15

    Titanium dioxide (TiO2)/polyacrylic acid (PAA) (TiO2/PAA) particles were formed by mixing PAA and an acidic solution of TiO2 nanoparticles in dimethylformamide (DMF) followed by heat treatment. TEM and particle analysis showed that the resulting particles had a narrow size distribution. The colloid was very stable and aggregation was not observed over a wide pH range (3-9) or at high salt concentration. The residual carboxylic acid of PAA could be modified via EDC/NHS activation to form an amide bond with a protein. An antibody was attached to the hybrid nanoparticle and specific binding to antigen was monitored by surface plasmon resonance. The results suggest that TiO2/PAA nanoparticles are candidates as the base component of a photocatalytic system with potential for substrate selectivity.

  5. Poly(aspartic acid) (PAA) hydrolases and PAA biodegradation: current knowledge and impact on applications.

    PubMed

    Hiraishi, Tomohiro

    2016-02-01

    Thermally synthesized poly(aspartic acid) (tPAA) is a bio-based, biocompatible, biodegradable, and water-soluble polymer that has a high proportion of β-Asp units and equivalent moles of D- and L-Asp units. Poly(aspartic acid) (PAA) hydrolase-1 and hydrolase-2 are tPAA biodegradation enzymes purified from Gram-negative bacteria. PAA hydrolase-1 selectively cleaves amide bonds between β-Asp units via an endo-type process, whereas PAA hydrolase-2 catalyzes the exo-type hydrolysis of the products of tPAA hydrolysis by PAA hydrolase-1. The novel reactivity of PAA hydrolase-1 makes it a good candidate for a biocatalyst in β-peptide synthesis. This mini-review gives an overview of PAA hydrolases with emphasis on their biochemical and functional properties, in particular, PAA hydrolase-1. Functionally related enzymes, such as poly(R-3-hydroxybutyrate) depolymerases and β-aminopeptidases, are compared to PAA hydrolases. This mini-review also provides findings that offer an insight into the catalytic mechanisms of PAA hydrolase-1 from Pedobacter sp. KP-2.

  6. A biocompatible calcium salt of hyaluronic acid grafted with polyacrylic acid.

    PubMed

    Nakagawa, Yoshiyuki; Nakasako, Satoshi; Ohta, Seiichi; Ito, Taichi

    2015-03-06

    We have synthesized hyaluronic acid (HA) grafted with polyacrylic acid (PAA) via controlled radical polymerization (CRP) in aqueous media. The grafted HA (HA-g-PAA) showed slow degradation by hyaluronidase compared with unmodified HA as a result of the steric hindrance produced by grafted PAA, and PAA was detached by hydrolysis and enzymatic degradation by lipase. It formed an insoluble salt immediately after mixing with Ca(2+) by the binding between grafted PAA and Ca(2+). Both HA-g-PAA and its salt showed good biocompatibility, especially to mesothelial cells in vitro. Finally, they were administered into mice subcutaneously and intraperitoneally. The residue of the material was observed 7 days after subcutaneous administration, while the material was almost cleared from the peritoneum 7 days after intraperitoneal administration with or without Ca(2+). HA-g-PAA is expected to be applicable to medical uses such as drug delivery in the peritoneum and for materials preventing peritoneal adhesion. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Ability of polyvinylpyrrolidone and polyacrylic acid to inhibit the crystallization of amorphous acetaminophen.

    PubMed

    Miyazaki, Tamaki; Yoshioka, Sumie; Aso, Yukio; Kojima, Shigeo

    2004-11-01

    The inhibition of crystallization of amorphous acetaminophen (ACTA) by polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) was studied using amorphous solid dispersions prepared by melt quenching. Co-melting with PVP and PAA decreased the average molecular mobility, as indicated by increases in glass transition temperature and enthalpy relaxation time. The ACTA/PAA dispersion exhibited much slower crystallization than the ACTA/PVP dispersion with a similar glass transition temperature value, indicating that interaction between ACTA and polymers also contributed to the stabilizing effect of these polymers. The carboxyl group of PAA may interact with the hydroxyl group of ACTA more intensely than the carbonyl group of PVP does, resulting in the stronger stabilizing effect of PAA. Dielectric relaxation spectroscopy showed that the number of water molecules tightly binding to PVP per monomer unit was larger than that to PAA. Furthermore, a small amount of absorbed water decreased the stabilizing effect of PVP, but not that of PAA. These findings suggest that the stronger stabilizing effect of PAA is due to the stronger interaction with ACTA. The ability of PAA to decrease the molecular mobility of solid dispersion was also larger than that of PVP, as indicated by the longer enthalpy relaxation time.

  8. [Enhanced reductive decoloration of methylene blue by polyacrylic acid modified zero-valent iron nanoparticles].

    PubMed

    He, Jing; Wang, Xiang-Yu; Wang, Pei; Liu, Kun-Qian

    2015-03-01

    Nano zerovalent iron ( NZVI) technology has attracted tremendous amount of interests for degrading a number of environmental contaminants found both in surface water and underground water. However, these nanoscale particles are prone to aggregate, which may result in the decrease of its reactivity in liquid phase. Iron nanoparticles (Fe NPs) modified with polyacrylic acid (PAA) has enhanced the dispersion of NZVI and reduced its agglomeration. For the first time, PAA modified NPs (PAA-Fe NPs) were used for degradation of methylene blue in water phase. The PAA-Fe NPs prepared were characterized in terms of TEM, SEM, XRD and specific surface area. The results indicated that, the surface area of PAA-Fe NPs was increased, compared with unmodified pristine zero-valent iron NPs, and PAA-Fe NPs were smoother with smaller particle size. With addition of 0.1 g x L(-1) of PAA, the decolorization efficiency of methylene blue by PAA-Fe NPs was 98.84% in 60 min, which was 27.32% higher than that of pristine Fe NPs. Decolorization efficiencies were also affected by initial pH value, initial concentration of methylene blue, dosage of PAA-Fe NPs, and degradation temperature. Kinetic analyses based on the experimental data illustrated that the decolorization reaction of methylene blue fitted well to the pseudo first-order kinetics model.

  9. Taste sensing with polyacrylic acid grafted cellulose membrane.

    PubMed

    Majumdar, Sarmishtha; Dey, Joykrishna; Adhikari, Basudam

    2006-03-15

    There are reports of fabrication of taste sensor by adsorbing lipids into Millipore filter paper, which improved the taste sensing efficiency of membrane remarkably. We have made an attempt to prepare taste sensor material by grafting polyacrylic acid (PAA) to cellulose. The research work covers polymer membrane preparation, morphology study, and structural characterization of the membrane and study of the taste sensing characteristics of this membrane for five different taste substances. FTIR spectroscopic analysis and SEM were done to get an idea about the structure and morphology of the PAA grafted cellulose membrane. Surface charge density of the membrane was estimated. The sensor characteristics like temporal stability, response stability, response to different taste substances, and reproducibility of sensing performance were studied using PAA grafted cellulose membrane. Sensor device prepared with this membrane has shown distinct response patterns for different taste substances in terms of membrane potential. Threshold concentrations of PAA grafted cellulose membrane for HCl, NaCl, quinine-hydrochloride (Q-HCl), sucrose and monosodium glutamate are 0.001 mM, 0.01 mM, 0.08 mM, 0.08 mM and 0.01 mM, respectively. The threshold concentrations except that in Q-HCl are below human threshold concentrations. Membranes also showed characteristic response patterns for organic acids like acetic acid, citric acid, formic acid, etc., mineral acids like HCl, H(2)SO(4) and HNO(3), etc., salts, bitter substances, sweet substances and umami substances. Sensor device prepared with this membrane has excellent shelf life.

  10. Chemically imaging the effects of the addition of nanofibrillated cellulose on the distribution of poly(acrylic acid) in poly(vinyl alcohol)

    Treesearch

    Craig Clemons; Julia Sedlmair; Barbara Illman; Rebecca Ibach; Carol Hirschmugl

    2013-01-01

    The distribution of poly(acrylic acid) (PAA) in model laminates of nanocellulose and poly(vinyl alcohol) (PVOH) was investigated by FTIR chemical imaging. The method was effective in spatially discerning the three components of the composite. PAA can potentially improve the performance of nanocellulose reinforced PVOH by not only crosslinking the PVOH matrix but also...

  11. Poly(acrylic acid) nanogel as a substrate for cellulase immobilization for hydrolysis of cellulose.

    PubMed

    Ahmed, Ibrahim Nasser; Chang, Ray; Tsai, Wei-Bor

    2017-04-01

    Cellulase was adsorbed onto poly(acrylic acid), PAA, nanogel, that was fabricated via inverse-phase microemulsion polymerization. The PAA nanogel was around 150nm in diameter and enriched with carboxyl groups. The surface charge of PAA nanogel depended on the pHs of the environment and affected the adsorption of cellulase. The temperature stability of the immobilized cellulase was greatly enhanced in comparison to the free enzyme, especially at high temperature. At 80°C, the immobilized cellulase remained ∼75% of hydrolytic activity, in comparison to ∼55% for the free cellulase. Furthermore, the immobilized cellulase was more active than the free enzyme in acidic buffers. The immobilized cellulase could be recovered via centrifugation and can be used repeatedly, although the recovery ratio needs further improvement. In conclusion, PAA nanogel has the potential in the application of enzyme immobilization for biochemical processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Matrix tablets based on thiolated poly(acrylic acid): pH-dependent variation in disintegration and mucoadhesion.

    PubMed

    Guggi, Davide; Marschütz, Michaela K; Bernkop-Schnürch, Andreas

    2004-04-15

    This study examined the influence of the pH on the mucoadhesive and cohesive properties of polyarcylic acid (PAA) and thiolated PAA. The pH of PAA (molecular mass: 450 kDa) and of a corresponding PAA-cysteine conjugate was adjusted to 3, 4, 5, 6, 7 and 8. The amount of immobilised thiol groups and disulfide bonds was determined via Ellman's reagent. Tablets were compressed out of each pH-batch of both thiolated and unmodified PAA and the swelling behaviour, the disintegration time and the mucoadhesiveness were evaluated. The amount of thiol/disulfide groups per gram thiolated PAA of pH 3 and pH 8 was determined to be 332 +/- 94 micromol and 162 +/- 46 micromol, respectively. The thiolated PAA tablets displayed a minimum four-fold higher water uptake compared to unmodified PAA tablets. A faster and higher water uptake of both polymer types was observed above pH 5. Thiolated polymer tablets showed a 3-20-fold more prolonged disintegration time than unmodified PAA tablets. The cohesiveness of PAA-cysteine conjugate increased at higher pH, whereas the unmodified PAA behaved inversely. A 3-7-fold stronger mucoadhesiveness was observed for the PAA-cysteine conjugate tablets compared to unmodified PAA tablets. For both thiolated and unmodified polymer the mucoadhesiveness was 2-4-fold enhanced below pH 5. The difference in mucoadhesion between the two polymer types was most pronounced at these lower pH values. In this study substantial information regarding the pH-dependence of mucoadhesion and cohesion of unmodified polyacrylates and of thiolated polyacrylates is provided, representing helpful basic information for an ameliorated deployment of these polymers.

  13. Antimicrobial activity of poly(acrylic acid) block copolymers.

    PubMed

    Gratzl, Günther; Paulik, Christian; Hild, Sabine; Guggenbichler, Josef P; Lackner, Maximilian

    2014-05-01

    The increasing number of antibiotic-resistant bacterial strains has developed into a major health problem. In particular, biofilms are the main reason for hospital-acquired infections and diseases. Once formed, biofilms are difficult to remove as they have specific defense mechanisms against antimicrobial agents. Antimicrobial surfaces must therefore kill or repel bacteria before they can settle to form a biofilm. In this study, we describe that poly(acrylic acid) (PAA) containing diblock copolymers can kill bacteria and prevent from biofilm formation. The PAA diblock copolymers with poly(styrene) and poly(methyl methacrylate) were synthesized via anionic polymerization of tert-butyl acrylate with styrene or methyl methacrylate and subsequent acid-catalyzed hydrolysis of the tert-butyl ester. The copolymers were characterized via nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and acid-base titrations. Copolymer films with a variety of acrylic acid contents were produced by solvent casting, characterized by atomic force microscopy (AFM) and tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The antimicrobial activity of the acidic diblock copolymers increased with increasing acrylic acid content, independent of the copolymer-partner, the chain length and the nanostructure. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Process for patterning features in poly(acrylic acid) for microelectronic applications

    NASA Astrophysics Data System (ADS)

    Feng, Ying; Smith, Connor S.; Burkett, Susan L.

    2017-05-01

    A method for patterning micro-scale features in a poly(acrylic acid) (PAA) film for engineering applications has been developed. Because PAA is a water-soluble polymer, careful attention has to be given during the development portion of the photolithographic process. To obtain well-defined patterns, development time was reduced by half following a regular photolithography exposure step. The remaining photoresist, and the PAA underneath it, were removed using a plasma ash process. After stripping the photoresist, polygonal windows such as triangles, rectangles, squares, pentagons, hexagons, heptagons, and octagons were created. This plasma ash process for patterning micro-scale features in PAA holds potential for fabrication of polymer microstructures, sacrificial layer micromolding, and patterned substrate micromolding. As a proof of concept, we applied these patterns to a solder-based self-assembly process to form 3D polyhedra.

  15. Electrophoretic deposition of polyacrylic acid and composite films containing nanotubes and oxide particles.

    PubMed

    Wang, Y; Deen, I; Zhitomirsky, I

    2011-10-15

    Electrophoretic deposition (EPD) method has been developed for the deposition of thin films of polyacrylic acid (PAA). This method allowed the formation of uniform films of controlled thickness on conductive substrates. It was shown that PAA can be used as a common dispersing agent suitable for charging and EPD of various materials, such as multiwalled carbon nanotubes, halloysite nanotubes, MnO(2), NiO, TiO(2) and SiO(2). The feasibility of EPD of composite films containing the nanotubes and oxide particles in a PAA matrix has been demonstrated. The kinetics of deposition and deposition mechanisms were investigated and discussed. The films were studied by thermogravimetric analysis, differential thermal analysis, X-ray diffraction and scanning electron microscopy. The results indicated that film thickness and composition can be varied. Obtained results pave the way for the fabrication of PAA and composite films for biomedical, electrochemical and other applications.

  16. Poly(acrylic acid)-grafted poly(N-isopropyl acrylamide) networks: preparation, characterization and hydrogel behavior.

    PubMed

    Yu, Rentong; Zheng, Sixun

    2011-01-01

    Poly(acrylic acid)-grafted poly(N-isopropylacrylamide) co-polymer networks (PNIPAAm-g-PAA) were prepared via the reversible addition-fragmentation transfer (RAFT) polymerization of N-isopropyl- acrylamide (NIPAAm) with trithiocarbonate-terminated PAA as a macromolecular chain-transfer agent in the presence of N,N-methylenebisacrylamide. The PNIPAAm-g-PAA co-polymer networks were characterized by means of Fourier transform infrared spectroscopy, differential scanning calorimetry and small-angle X-ray scattering. It is found that the PNIPAAm-g-PAA co-polymer networks were microphase-separated, in which the microdomains of PNIPAAm-PAA interpolymer complexes were dispersed into the PNIPAAm matrix. The PNIPAAm-g-PAA hydrogels displayed a dual response to temperature and pH values. The thermoresponsive properties of PNIPAAm-g-PAA networks were investigated. Below the volume phase transition temperatures, the PNIPAAm-g-PAA hydrogels possessed much higher swelling ratios than control PNIPAAm hydrogel. In terms of swelling, deswelling and reswelling tests, it is judged that the PNIPAAm-g-PAA hydrogels displayed faster response to the external temperature changes than control PNIPAAm hydrogel. The improved thermoresponsive properties of hydrogels are ascribed to the formation of PAA-grafted PNIPAAm networks, in which the water-soluble PAA chains behave as the hydrophiphilic tunnels and allow water molecules to go through and, thus, to accelerate the diffusion of water molecules.

  17. Removal of lead from aqueous solutions by a poly(acrylic acid)/bentonite nanocomposite

    NASA Astrophysics Data System (ADS)

    Rafiei, H. R.; Shirvani, M.; Ogunseitan, O. A.

    2016-11-01

    We synthesized a novel poly acrylic acid-organobentonite (PAA-Bent) nanocomposite by successive intercalation of cetyltrimethylammonium (CTA) surfactant and polyacrylic acid (PAA) into the bentonite (Bent) interlayer spaces. The surfactant-modified clay (CTA-Bent) and PAA-Bent nanocomposite were characterized by XRD and FT-IR techniques and used for removal of Pb(II) from aqueous solution. The XRD results confirmed the intercalation of CTA and PAA into the interlayer spaces of the bentonite increasing the d 001 spacing of the clay from 12.2 up to 38.9 Å. FT-IR analysis of the modified clay samples revealed the functional groups of CTA and PAA constituents alighted on the bentonite surfaces. Maximum Pb sorption capacity of the Bent and PAA-Bent predicted by Langmuir model were 52.3 and 93.0 mg g-1, respectively, showing that the synthesized nanocomposite superiorly adsorbed Pb from the solution as compared to the Bent. The maximum Pb removal efficiency of 99.6 % was achieved by the nanocomposite at 25 °C with <30 min contact time for a 7.5 g L-1 solid-to-liquid ratio and an initial metal concentration of 400 mg L-1. The results indicated that PAA-Bent nanocomposite can be efficiently used as a superadsorbent for the removal of Pb(II) from aqueous solution.

  18. Release of triamcinolone acetonide from mucoadhesive polymer composed of chitosan and poly(acrylic acid) in vitro.

    PubMed

    Ahn, Jae-Soon; Choi, Hoo-Kyun; Chun, Myong-Kwan; Ryu, Jei-Man; Jung, Jae-Hee; Kim, Yue-Un; Cho, Chong-Su

    2002-03-01

    Transmucosal drug delivery (TMD) system using mucoadhesive polymer has been recently interested due to the rapid onset of action, high blood level, avoidance of the first-pass effect and the exposure of the drug to the gastrointestinal tract. A novel mucoadhesive polymer complex composed of chitosan and poly(acrylic acid) (PAA) was prepared by template polymerization of acrylic acid in the presence of chitosan for the TMD system. Triamcinolone acetonide (TAA) was loaded into the chitosan/PAA polymer complex film. TAA was evenly dispersed in chitosan, PAA polymer complex film without interaction with polymer complex. Release behavior of TAA from the mucoadhesive polymer film was dependent on time, pH, loading content of drug, and chitosan PAA ratio. The analysis of the drug release from the mucoadhesive film showed that TAA might be released from the chitosan/PAA polymer complex film through non-Fickian diffusion mechanism.

  19. Dynamic peracetic acid (PAA) exposure, a treatment strategy against ectoparasites

    USDA-ARS?s Scientific Manuscript database

    The search for alternative therapeutic agents is a difficult and laborious task. The use of peracetic acid (PAA) has recently been evaluated as an alternative compound for disinfection (Gustavino et al., 2005). In addition to having a broad antimicrobial spectrum, PAA does not contribute to the form...

  20. Effect of anions and humic acid on the performance of nanoscale zero-valent iron particles coated with polyacrylic acid.

    PubMed

    Kim, Hong-Seok; Ahn, Jun-Young; Kim, Cheolyong; Lee, Seockheon; Hwang, Inseong

    2014-10-01

    Effects of anions (NO3(-), HCO3(-), Cl(-), SO4(2-)) and humic acid on the reactivity and core/shell chemistries of polyacrylic acid-coated nanoscale zero-valent iron (PAA-NZVI) and inorganically modified NZVI (INORG-NZVI) particles were investigated. The reactivity tests under various ion concentrations (0.2-30mN) revealed the existence of a favorable molar ratio of anion/NZVI that increased the reactivity of NZVI particles. The presence of a relatively small amount of humic acid (0.5mgL(-1)) substantially decreased the INORG-NZVI reactivity by 76%, whereas the reactivity of PAA-NZVI decreased only by 12%. The XRD and TEM results supported the role of the PAA coating of PAA-NZVI in impeding the oxidation of the Fe(0) core by groundwater solutes. This protective role provided by the organic coating also resulted in a 2.3-fold increase in the trichloroethylene (TCE) reduction capacity of PAA-NZVI compared to that of INORG-NZVI in the presence of anions/humic acid. Ethylene and ethane were simultaneously produced as the major reduction products of TCE in both NZVI systems, suggesting that a hydrodechlorination occurred without the aid of metallic catalysts. The PAA coating, originally designed to improve the mobility of NZVI, enhanced TCE degradation performances of NZVI in the presence of anions and humic acid.

  1. Protein polymer conjugates: improving the stability of hemoglobin with poly(acrylic acid).

    PubMed

    Thilakarathne, Vindya; Briand, Victoria A; Zhou, Yuxiang; Kasi, Rajeswari M; Kumar, Challa V

    2011-06-21

    The synthesis, characterization, and evaluation of a novel polymer-protein conjugate are reported here. The covalent conjugation of high-molecular weight poly(acrylic acid) (PAA) to the lysine amino groups of met-hemoglobin (Hb) resulted in the covalent conjugation of Hb to PAA (Hb-PAA conjugate), as confirmed by dialysis and electrophoresis studies. The retention of native-like structure of Hb in Hb-PAA was established from Soret absorption, circular dichroism studies, and the redox activity of the iron center in Hb-PAA. The peroxidase-like activities of the Hb-PAA conjugate further confirmed the retention of Hb structure and biological activity. Thermal denaturation of the conjugate was investigated by differential scanning calorimetry and steam sterilization studies. The Hb-PAA conjugate indicated an improved denaturation temperature (T(d)) when compared to that of the unmodified Hb. One astonishing observation was that polymer conjugation significantly enhanced the Hb-PAA storage stability at room temperature. After 120 h of storage at room temperature in phosphate-buffered saline (PBS) at pH 7.4, for example, Hb-PAA retained 90% of its initial activity and unmodified Hb retained <60% of its original activity under identical conditions of buffer, pH, and temperature. Our conjugate demonstrates the key role of polymers in enhancing Hb stability via a very simple, efficient, general route. Water-swollen, lightly cross-linked, stable Hb-polymer nanogels of 100-200 nm were produced quickly and economically by this approach for a wide variety of applications.

  2. Conjugation, characterization and toxicity of lipophosphoglycan-polyacrylic acid conjugate for vaccination against leishmaniasis

    PubMed Central

    2013-01-01

    Research on the conjugates of synthetic polyelectrolytes with antigenic molecules, such as proteins, peptides, or carbohydrates, is an attractive area due to their highly immunogenic character in comparison to classical adjuvants. For example, polyacrylic acid (PAA) is a weak polyelectrolyte and has been used in several biomedical applications such as immunological studies, drug delivery, and enzyme immobilization. However, to our knowledge, there are no studies that document immune-stimulant properties of PAA in Leishmania infection. Therefore, we aimed to develop a potential vaccine candidate against leishmaniasis by covalently conjugating PAA with an immunologically vital molecule of lipophosphoglycan (LPG) found in Leishmania parasites. In the study, LPG and PAA were conjugated by a multi-step procedure, and final products were analyzed with GPC and MALDI-TOF MS techniques. In cytotoxicity experiments, LPG-PAA conjugates did not indicate toxic effects on L929 and J774 murine macrophage cells. We assume that LPG-PAA conjugate can be a potential vaccine candidate, and will be immunologically characterized in further studies to prove its potential. PMID:23731716

  3. Conjugation, characterization and toxicity of lipophosphoglycan-polyacrylic acid conjugate for vaccination against leishmaniasis.

    PubMed

    Topuzogullari, Murat; Cakir Koc, Rabia; Dincer Isoglu, Sevil; Bagirova, Melahat; Akdeste, Zeynep; Elcicek, Serhat; Oztel, Olga N; Yesilkir Baydar, Serap; Canim Ates, Sezen; Allahverdiyev, Adil M

    2013-06-03

    Research on the conjugates of synthetic polyelectrolytes with antigenic molecules, such as proteins, peptides, or carbohydrates, is an attractive area due to their highly immunogenic character in comparison to classical adjuvants. For example, polyacrylic acid (PAA) is a weak polyelectrolyte and has been used in several biomedical applications such as immunological studies, drug delivery, and enzyme immobilization. However, to our knowledge, there are no studies that document immune-stimulant properties of PAA in Leishmania infection. Therefore, we aimed to develop a potential vaccine candidate against leishmaniasis by covalently conjugating PAA with an immunologically vital molecule of lipophosphoglycan (LPG) found in Leishmania parasites. In the study, LPG and PAA were conjugated by a multi-step procedure, and final products were analyzed with GPC and MALDI-TOF MS techniques. In cytotoxicity experiments, LPG-PAA conjugates did not indicate toxic effects on L929 and J774 murine macrophage cells. We assume that LPG-PAA conjugate can be a potential vaccine candidate, and will be immunologically characterized in further studies to prove its potential.

  4. Poly(acrylic acid) brushes pattern as a 3D functional biosensor surface for microchips

    NASA Astrophysics Data System (ADS)

    Wang, Yan-Mei; Cui, Yi; Cheng, Zhi-Qiang; Song, Lu-Sheng; Wang, Zhi-You; Han, Bao-Hang; Zhu, Jin-Song

    2013-02-01

    Poly(acrylic acid) (PAA) brushes, a novel three dimensional (3D) precursor layer of biosensor or protein microarrays, possess high protein loading level and low non-specific protein adsorption. In this article, we describe a simple and convenient way to fabricate 3D PAA brushes pattern by microcontact printing (μCP) and characterize it with FT-IR and optical microscopy. The carboxyl groups of PAA brushes can be applied to covalently immobilize protein for immunoassay. Thriving 3D space made by patterning PAA brushes thin film is available to enhance protein immobilization, which is confirmed by measuring model protein interaction between human immunoglobulin G (H-IgG) and goat anti-H-IgG (G-H-IgG) with fluorescence microscopy and surface plasmon resonance imaging (SPRi). As expected, the SPRi signals of H-IgG coating on 3D PAA brushes pattern and further measuring specific binding with G-H-IgG are all larger than that of 3D PAA brushes without pattern and 2D bare gold surface. We further revealed that this surface can be used for high-throughput screening and clinical diagnosis by label-free assaying of Hepatitis-B-Virus surface antibody (HBsAb) with Hepatitis-B-Virus surface antigen (HBsAg) concentration array chip. The linearity range for HBsAb assay is wider than that of conventional ELISA method.

  5. Formation of calcium carbonate films on chitosan substrates in the presence of polyacrylic acid

    SciTech Connect

    He, Linghao; Xue, Rui; Song, Rui

    2009-05-15

    In this investigation, chitosan membranes with different surface average degrees of deacetylation (DA) are prepared and then are employed as the support matrix to culture calcium carbonate (CaCO{sub 3}). In the presence of high concentration of polyacrylic acid (PAA), the CaCO{sub 3} films obtained on the surface of all chitosan films mainly consisted of vaterite, which suggests the presence of bulk PAA plays an overwhelming part in stabilizing the vaterite. As a comparison, the influences of active groups indicate that only in case of low concentration PAA the thin CaCO{sub 3} films grown on chitosan with 8% DA mainly consisted of vaterite owing to the strong nucleation ability of -NH{sub 2} group, whereas, for those grown on chitosan with 80% DA the CaCO{sub 3} films mainly consisted of aragonite. A more complex scenario revealed that in the case of intermediate concentration of PAA the formed polymorphs behave as mixtures of vaterite and aragonite. - Graphical abstract: Chitosan membranes with different degrees of deacetylation (DA) are employed as support to culture calcium carbonate (CaCO{sub 3}). In high concentration of polyacrylic acid (PAA), the CaCO{sub 3} films obtained consisted of vaterite. However, the CaCO{sub 3} film grown on chitosan with 8% DA mainly consisted of vaterite as opposed to aragonite for chitosan with 8% DA. The schematic presentation of the formation of calcium carbonate on chitosan films with different degrees of acetylation in the presence of PAA with low-, mid- and high concentrations.

  6. Decolourization performance in C. I. Vat Yellow 1 aqueous suspension using hydrophobically modified poly(acrylic acid).

    PubMed

    Chen, J; Chen, M C

    2011-01-01

    A series of hydrophobically modified poly(acrylic acid) (PAA), poly(2-phenoxyethyl acrylate-co-acrylic acid) (poly(PHEA-co-AA)), have been synthesized and characterized by Ubbelohde type viscometry, Nuclear Magnetic Resonance (1H NMR) spectrometry and Differential Scanning Calorimetry (DSC). The shear thinning Non-Newtonian fluid behavior of their aqueous solution and the dependence on pH and hydrophobic group contents were found through apparent viscosity and rheological property investigating. Decolourization performance in C. I. Vat Yellow 1 aqueous suspension was evaluated through visible absorbance data. Decolourization performance of hydrophobically associated polymer indicates two times better than that of PAA. The quantitative relationship was mainly studied.

  7. Dually cross-linked single network poly(acrylic acid) hydrogels with superior mechanical properties and water absorbency.

    PubMed

    Zhong, Ming; Liu, Yi-Tao; Liu, Xiao-Ying; Shi, Fu-Kuan; Zhang, Li-Qin; Zhu, Mei-Fang; Xie, Xu-Ming

    2016-06-28

    Poly(acrylic acid) (PAA) hydrogels with superior mechanical properties, based on a single network structure with dual cross-linking, are prepared by one-pot free radical polymerization. The network structure of the PAA hydrogels is composed of dual cross-linking: a dynamic and reversible ionic cross-linking among the PAA chains enabled by Fe(3+) ions, and a sparse covalent cross-linking enabled by a covalent cross-linker (Bis). Under deformation, the covalently cross-linked PAA chains remain intact to maintain their original configuration, while the Fe(3+)-enabled ionic cross-linking among the PAA chains is broken to dissipate energy and then recombined. It is found that the mechanical properties of the PAA hydrogels are significantly influenced by the contents of covalent cross-linkers, Fe(3+) ions and water, which can be adjusted within a substantial range and thus broaden the applications of the hydrogels. Meanwhile, the PAA hydrogels have excellent recoverability based on the dynamic and reversible ionic cross-linking enabled by Fe(3+) ions. Moreover, the swelling capacity of the PAA hydrogels is as high as 1800 times in deionized water due to the synergistic effects of ionic and covalent cross-linkings. The combination of balanced mechanical properties, efficient recoverability, high swelling capacity and facile preparation provides a new method to obtain high-performance hydrogels.

  8. Reversible fluorescence quenching by micelle selective benzophenone-induced interactions between brij micelles and polyacrylic acids: implications for chemical sensors.

    PubMed

    Bandyopadhyay, Prasun; Ghosh, Amit K

    2010-09-09

    The fluorescence response of pyrene has been studied in the presence of nonionic brij micelles and poly(acrylic acid) (PAA) with benzophenone (BP) as a neutral hydrophobic quencher. Pyrene emission is quenched ("off" state) in the presence of BP in brij 35 (polyoxyethylene-23-lauryl ether) and brij 56 (polyoxyethylene-10-cetyl ether) micelles. Quenched pyrene emission is selectively recovered ("on" state) for brij 35 micelles with the addition of PAA (starting conc 2.0 x 10(-5) M). Due to the interaction of PAA and brij 35 micelles and the relatively easier accessibility of PAA polymer chains near the bulky polyoxyethylene chain of brij 35 micelles, the chances of BP partition inside the hydrophobic polymer coil are more compared to brij 56 micelles. The PAA sensing ability of the "brij 35:pyrene:BP" system is dependent on the molecular weight (M) of the polymer. Fluorescence recovery has been observed with PAA (M approximately 150000) and complete recovery has been recorded with high M of PAA (M approximately 450000); however, no fluorescence change is observed in the presence of low M of PAA (M approximately 2000). In solution, such selective reversible fluorescence quenching has the potential for a new class of highly sensitive chemical sensor systems.

  9. Novel conducting polymer electrolyte biosensor based on poly(1-vinyl imidazole) and poly(acrylic acid) networks.

    PubMed

    Arslan, Ahu; Kiralp, Senem; Toppare, Levent; Bozkurt, Ayhan

    2006-03-14

    Biosensor construction and characterization studies of poly(acrylic acid) (PAA) and poly(1-vinyl imidazole) (PVI) complex systems have been carried out. The biosensors were prepared by mixing PAA with PVI at several stoichiometric ratios, x (molar ratio of the monomer repeat units). The enzyme, invertase, was entrapped in the PAA/PVA interpenetrating polymer networks during complexation. Modifications were made on the PAA/PVI conducting polymer electrolyte matrixes to improve the stability and performance of the polymer electrolyte-based enzyme biosensor. The maximum reaction rate (V(max)) and Michaelis-Menten constant (K(m)) were investigated for the immobilized invertase. The temperature and pH optimization, operational stability, and shelf life of the polymer electrolyte biosensor were also examined.

  10. Poly(acrylic acid) modifying bentonite with in-situ polymerization for removing lead ions.

    PubMed

    He, Y F; Zhang, L; Yan, D Z; Liu, S L; Wang, H; Li, H R; Wang, R M

    2012-01-01

    In this paper, a new kind of poly(acrylic acid) modified clay adsorbent, the poly(acrylic acid)/bentonite composite (PAA/HB) was prepared by in-situ polymerization, and utilized to remove lead(II) ions from solutions. The maximum adsorption of adsorbent is at pH 5 for metal ions, whereas the adsorption starts at pH 2. The effects of contact time (5-60 min), initial concentration of metal ions (200-1,000 mg/L) and adsorbent dosage (0.04-0.12 g/100 mL) have been reported in this article. The experimental data were investigated by means of kinetic and equilibrium adsorption isotherms. The kinetic data were analyzed by the pseudo-first-order and pseudo-second-order equation. The experimental data fitted the pseudo-second-order kinetic model very well. Langmuir and Freundlich isotherms were tried for the system to better understand the adsorption isotherm process. The maximal adsorption capacity of the lead(II) ions on the PAA/HB, as calculated from the Langmuir model, was 769.2 mg/g. The results in this study indicated that PAA/HB was an attractive candidate for removing lead(II) (99%).

  11. Structure and Proton Conductivity in Mixtures of Poly(acrylic acid) and Imidazole

    NASA Astrophysics Data System (ADS)

    Yang, Han-Chang; Griffin, Philip J.; Winey, Karen I.; University of Pennsylvania Team

    2015-03-01

    Proton conductivity in polymer electrolyte membranes (PEMs) typically involves water, which requires that during operation the humidity of the PEM be carefully controlled. In contrast, anhydrous protic polymer membranes promote proton transport by incorporating heterocyclic molecules, such as imidazole and its derivatives, into acid-containing polymers. In this work, we explore the interplay between nanoscale-structure and proton conduction of poly(acrylic acid) (PAA) blended at varying compositions with 2-ethyl-4-methylimidazole (EMI). We present the glass transition temperature from differential scanning calorimetry, morphology characterization from X-ray scattering, and proton conductivity from electrical impedance spectroscopy.

  12. Polyacrylic acid-coated iron oxide nanoparticles for targeting drug resistance in mycobacteria.

    PubMed

    Padwal, Priyanka; Bandyopadhyaya, Rajdip; Mehra, Sarika

    2014-12-23

    The emergence of drug resistance is a major problem faced in current tuberculosis (TB) therapy, representing a global health concern. Mycobacterium is naturally resistant to most drugs due to export of the latter outside bacterial cells by active efflux pumps, resulting in a low intracellular drug concentration. Thus, development of agents that can enhance the effectiveness of drugs used in TB treatment and bypass the efflux mechanism is crucial. In this study, we present a new nanoparticle-based strategy for enhancing the efficacy of existing drugs. To that end, we have developed poly(acrylic acid) (PAA)-coated iron oxide (magnetite) nanoparticles (PAA-MNPs) as efflux inhibitors and used it together with rifampicin (a first line anti-TB drug) on Mycobacterium smegmatis. PAA-MNPs of mean diameter 9 nm interact with bacterial cells via surface attachment and are then internalized by cells. Although PAA-MNP alone does not inhibit cell growth, treatment of cells with a combination of PAA-MNP and rifampicin exhibits a synergistic 4-fold-higher growth inhibition compared to rifampicin alone. This is because the combination of PAA-MNP and rifampicin results in up to a 3-fold-increased accumulation of rifampicin inside the cells. This enhanced intracellular drug concentration has been explained by real-time transport studies on a common efflux pump substrate, ethidium bromide (EtBr). It is seen that PAA-MNP increases the accumulation of EtBr significantly and also minimizes the EtBr efflux in direct proportion to the PAA-MNP concentration. Our results thus illustrate that the addition of PAA-MNP with rifampicin may bypass the innate drug resistance mechanism of M. smegmatis. This generic strategy is also found to be successful for other anti-TB drugs, such as isoniazid and fluoroquinolones (e.g., norfloxacin), only when stabilized, coated nanoparticles (such as PAA-MNP) are used, not PAA or MNP alone. We hence establish coated nanoparticles as a new class of efflux

  13. Antiviral activity of polyacrylic and polymethacrylic acids. I. Mode of action in vitro.

    PubMed

    De Somer, P; De Clercq, E; Billiau, A; Schonne, E; Claesen, M

    1968-09-01

    Polyacrylic acid (PAA) and polymethacrylic acid (PMAA) were investigated for their antiviral properties in tissue culture. Compared to other related polyanions, as dextran sulfate, polystyrene sulfonate, polyvinyl sulfate, and polyphloroglucinol phosphate, PAA and PMAA were found to be significantly more antivirally active and less cytotoxic. PMAA added 24 hr prior to virus inoculation inhibited viral growth most efficiently but it was still effective when added 3 hr after infection. Neither a direct irreversible action on the virus nor inhibition of virus penetration into the cell could explain the antiviral activity of PMAA. PMAA inhibited the adsorption of the virus to the host cell and suppressed the one-cycle viral synthesis in tissue cultures inoculated with infectious RNA.

  14. ABS polymer electroless plating through a one-step poly(acrylic acid) covalent grafting.

    PubMed

    Garcia, Alexandre; Berthelot, Thomas; Viel, Pascal; Mesnage, Alice; Jégou, Pascale; Nekelson, Fabien; Roussel, Sébastien; Palacin, Serge

    2010-04-01

    A new, efficient, palladium- and chromium-free process for the electroless plating of acrylonitrile-butadiene-styrene (ABS) polymers has been developed. The process is based on the ion-exchange properties of poly(acrylic acid) (PAA) chemically grafted onto ABS via a simple and one-step method that prevents using classical surface conditioning. Hence, ABS electroless plating can be obtained in three steps, namely: (i) the grafting of PAA onto ABS, (ii) the copper Cu(0) seeding of the ABS surface, and (iii) the nickel or copper metallization using commercial-like electroless plating bath. IR, XPS, and SEM were used to characterize each step of the process, and the Cu loading was quantified by atomic absorption spectroscopy. This process successfully compares with the commercial one based on chromic acid etching and palladium-based seed layer, because the final metallic layer showed excellent adhesion with the ABS substrate.

  15. Buccal delivery of acyclovir from films based on chitosan and polyacrylic acid.

    PubMed

    Rossi, Silvia; Sandri, Giuseppina; Ferrari, Franca; Bonferoni, Maria Cristina; Caramella, Carla

    2003-01-01

    The aim of the present work was to investigate the possibility of achieving buccal delivery of a problematic drug, acyclovir, from films based on chitosan hydrochloride (HCS) and polyacrylic acid sodium salt (PAA). At first, the ionic interaction between HCS and PAA in distilled water was investigated by means of rheological and turbidimetric analysis. Films containing 1 mg/cm2 of acyclovir and based on pure HCS and on HCS and PAA mixed in different ratios were prepared by casting technique. The films were subjected to hydration, rheological, mucoadhesion, drug release, "wash away," and permeation/penetration measurements. A commercial cream containing acyclovir and an aqueousacyclovir suspension were used as references. The addition of PAA to HCS produced a decrease in film hydration. Films based on HCS/PAA weight ratio close to interaction productstoichiometry were characterized by higher rigidity and better "wash away" properties with respect to the other films and the reference formulation. The worst mucoadhesive properties were shown by films based on mixing ratios close to interaction product stoichiometry. The addition of PAA to HCS produced a lowering in drug release profile. All the films examined promoted the permeation of acyclovir across porcine cheek epithelium when compared with acyclovir suspension and the commercial cream. The penetration enhancement properties were affected by the mixing ratio of the two polymers. The film based on 1/1.3 HCS/PAA weight ratio, besides possessing the best resilience properties on the mucosa, was also characterized by the highest permeation profile and, therefore, represents a promising formulation for buccal delivery of acyclovir.

  16. Polyethylenimine-polyacrylic acid nanocomposites: Type of bonding does influence the gene transfer efficacy and cytotoxicity.

    PubMed

    Tripathi, Sushil K; Ahmadi, Zeba; Gupta, Kailash C; Kumar, Pradeep

    2016-04-01

    The main aim of the current study is to compare the physicochemical properties, cytotoxicity and gene-transfer ability of electrostatically and covalently linked nanocomposites of polyethylenimine (PEI) and polyacrylic acid (PAA) on mammalian cells. Two series of nanocomposites, ionic PEI-PAA (iPP) and covalent PEI-PAA (cPP), were synthesized by varying the amounts of polyacrylic acid (PAA). Physicochemical characterization revealed that iPP nanopcomposites were of bigger sized than cPP nanocomposites with zeta potential almost comparable. Nucleic acid binding assay displayed that iPP and cPP nanocomposites, having sufficient cationic charge, efficiently interacted with plasmid DNA and completely retarded its electrophoretic mobility on agarose gel. In vitro MTT assay showed slightly higher cell viability of cPP/pDNA complexes over their ionic counterparts. Both the series of nanocomposite/pDNA complexes exhibited considerably higher transfection efficacy compared to pDNA complexes of native bPEI and the standard transfection reagent, Lipofectamine, with cPP/pDNA complexes performed much better than iPP/pDNA complexes. Flow cytometry further confirmed these findings where cPP-4/pDNA complex showed transfection in ∼ 85% HEK293 cells, while iPP-2/pDNA complex transfected ∼ 67% HEK293 cells. Lipofectamine/pDNA and bPEI/pDNA complexes could transfect just ∼ 35% and ∼ 26% HEK293 cells. All these results demonstrate the superiority of covalently linked nanocomposites (cPP) which could be used as efficient carriers for nucleic acids in future gene delivery applications.

  17. Preparation and Characterization of Chitosan Poly(acrylic acid) Magnetic Microspheres

    PubMed Central

    Guo, Liang; Liu, Guang; Hong, Ruo-Yu; Li, Hong-Zhong

    2010-01-01

    Spherical microparticles, capable of responding to magnetic fields, were prepared by encapsulating dextran-coated Fe3O4 nanoparticles into chitosan poly(acrylic acid) (PAA) microspheres template. The obtained magnetic microspheres were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and thermogravimetry (TG). The results showed that the microspheres were formed and demonstrated magnetic behavior in an applied magnetic field. In addition, magnetite particles were well encapsulated and the composite particles have high magnetite content, which was more than 40%. PMID:20714433

  18. Thermoresponsive gelling behavior of concentrated alumina suspensions containing poly(acrylic acid) and PEO-PPO-PEO copolymer.

    PubMed

    Kondo, Akira; Xu, Hui; Abe, Hiroya; Naito, Makio

    2012-05-01

    Thermoresponsive gelling behavior of concentrated alumina suspensions with poly(acrylic acid) (PAA) and triblock copolymer (PEO(101)-PPO(56)-PEO(101), Pluronic F127) was investigated as a function of PAA concentration (0.4-1.2 mass%) for ceramic solid free forming. The copolymer species assemble into micelles at temperatures above 15°C, yielding aqueous physical gel. In this study, the concentrated alumina aqueous suspensions (φ=35 vol%) were first prepared using the anionic dispersant of PAA, and then the copolymer species (10 mass%) were dissolved at a cooled temperature at 10°C. The addition of the copolymer species had a negligible influence on the adsorption state of PAA onto the alumina surfaces. The PAA concentration needed for the saturation adsorption on the alumina surfaces was ~0.6 mass%. When the PAA concentration was this value or slightly less, the suspension became gel state at 30°C from low viscous state at 10°C. The thermally induced alumina gel had excellent viscoelastic properties, and thereby the three dimensional periodic ceramic structures were successfully fabricated by a direct colloidal printing method that using the gels as "solid" inks at the room temperature. On the other hand, when it exceeded the saturation adsorption limit, the gelling behavior was not observed, indicating that the non-adsorbing PAA species may partly suppress the micellization of the copolymer on the heating.

  19. Biodegradability and mechanical properties of poly(butylene succinate) composites with finely dispersed hydrophilic poly(acrylic acid)

    NASA Astrophysics Data System (ADS)

    Mizuno, Sawako; Hotta, Atsushi

    2014-03-01

    Biodegradability and mechanical properties of aliphatic poly(butylene succinate) (PBS) films with finely dispersed hydrophilic poly(acrylic acid) (PAA) were investigated. First, 3.5 wt% of PAA was chemically grafted onto the surface of the PBS films (surface-grafted PBS) by photo grafting polymerization, and then the grafted PAA was homogeneously and finely dispersed into PBS by dissolving the surface-grafted PBS into chloroform before mixing and drying to get solid PAA-dispersed PBS. Degradation of these modified PBS was investigated using gel permeation chromatography (GPC) and tensile testing. According to the GPC results, it was found that the PAA-dispersed PBS had intermediate biodegradability with the intermediate water intake, and the reaction constant of PAA-dispersed PBS was in between those of untreated PBS and surface-grafted PBS, in fact 25% higher and 17% lower, respectively. The experimental results presented that the biodegradability of PBS could be well controlled by the dispersion of PAA, possibly leading to the widespread use of PBS for biodegradable polymers.

  20. Ultrasound stimulus effect on hydrogen bonding in networked alumina and polyacrylic acid slurry.

    PubMed

    Ngoc, Ngo Le; Takaomi, Kobayashi

    2010-01-01

    The influence of ultrasound (US) on the viscosity of aqueous slurry composing polyacrylic acid (PAA) and alumina was studied. For exposure to an aqueous slurry solution, US waves emitted at three different frequencies of 28, 45, and 100 kHz were used. Results show that the stimulus effect of US on viscosity change was a breakage of the hydrogen bonding networks of alumina and PAA in the slurry solution. That decrease in viscosity was enhanced strongly by US exposure as the output power was increased from 175 to 300 W. In addition, a lower US frequency was effective for slurry viscosity reduction. The reduced viscosity of the slurry also depended on the solution pH. After US was stopped, the viscosity increased gradually and recovered to its original value within about 15 min. The stimulus effect on the viscosity change was cycled by US.

  1. Poly(acrylic acid)-stabilized colloidal gold nanoparticles: synthesis and properties.

    PubMed

    Jans, Hilde; Jans, Karolien; Lagae, Liesbet; Borghs, Gustaaf; Maes, Guido; Huo, Qun

    2010-11-12

    Combining the intriguing optical properties of gold nanoparticles with the inherent physical and dynamic properties of polymers can give rise to interesting hybrid nanomaterials. In this study, we report the synthesis of poly(acrylic acid) (PAA)-capped gold nanoparticles. The polyelectrolyte-wrapped gold nanoparticles were fully characterized and studied via a combination of techniques, i.e. UV-vis and infrared spectroscopy, dark field optical microscopy, SEM imaging, dynamic light scattering and zeta potential measurements. Although PAA-capped nanoparticles have been previously reported, this study revealed some interesting aspects of the colloidal stability and morphological change of the polymer coating on the nanoparticle surface in an electrolytic environment, at various pH values and at different temperatures.

  2. Efficient biocatalysis in organic media with hemoglobin and poly(acrylic acid) nanogels.

    PubMed

    Zore, Omkar V; Lenehan, Patrick J; Kumar, Challa V; Kasi, Rajeswari M

    2014-05-13

    We previously reported that the stability and aqueous catalytic activity of met-hemoglobin (Hb) was improved when covalently conjugated with poly(acrylic acid) (PAA). In the current study, the Hb-PAA-water interface was modified to improve Hb catalytic efficiency in organic solvents (0-80% v/v organic solvent; remainder is the conjugate, the substrate, and water). The protein-polymer-solvent interface modification was achieved by esterifying the carboxylic acid groups of Hb-PAA with ethanol (EtOH) or 1-propanol (1-prop) after activation with carbodiimide. The resulting esters (Hb-PAA-Eth and Hb-PAA-1-prop, respectively) showed high peroxidase-like catalytic activities in acetonitrile (ACN), dimethylformamide (DMF), EtOH, and methanol (MeOH). Catalytic activities depended on the log(P) values of the solvents, which is a measure of solvent lipophilicity. The highest weighted-average activities were noted in MeOH for all three conjugates, and the lowest average activities were noted in DMF for two of the conjugates. Interestingly, the average activities of the conjugates were higher than that of Hb in all solvents except in ACN. The ratio of the catalytic rate constant (kcat) to the Michaelis constant (KM), the catalytic efficiency, for Hb-PAA-Eth in MeOH was the highest noted, and it is ~3-fold higher than that of Hb in buffer; conjugates offered higher efficiencies than Hb at most solvent compositions. This is the very first general, versatile, modular strategy of coupling the enhanced stability of Hb with improved activity in organic solvents via the chemical manipulation of the polymer shell around Hb and provides a robust approach to efficient biocatalysis in organic solvents.

  3. Characterization of a planar poly(acrylic acid) brush as a materials coating for controlled protein immobilization.

    PubMed

    Hollmann, Oliver; Czeslik, Claus

    2006-03-28

    The adsorption of two different proteins at a planar poly(acrylic acid) (PAA) brush was studied as a function of the ionic strength of the protein solutions applying total internal reflection fluorescence (TIRF) spectroscopy. Planar PAA brushes were prepared with a grafting density of 0.11 nm(-2) and were characterized using X-ray reflectometry. Hen egg-white lysozyme and bovine serum albumin (BSA) were used as model proteins, which have a net positive and negative charge at neutral pH-values, respectively. It has been found that both proteins adsorb strongly at a planar PAA brush at low ionic strength. Whereas lysozyme interacts with a PAA brush under electrostatic attraction at neutral pH-values, BSA binds under electrostatic repulsion at pH > 5. Even at pH = 8, significant amounts of BSA are adsorbed to a planar PAA brush. In addition, the reversibility of BSA adsorption has been characterized. Dilution of a BSA solution leads to an almost complete desorption of BSA from a PAA brush at short contact times. When the ionic strength of the protein solutions is increased to about 100-200 mM, a planar PAA brush appears largely protein-resistant, regardless of the protein net charge. The results of this study indicate that the salt-dependent protein affinity of a PAA brush represents a unique effect that must be explained by a novel protein-binding mechanism. On the basis of a recent model, it is suggested that a release of counterions is the most probable driving force for protein adsorption at a PAA brush. In a general view, this study characterizes a planar PAA brush as a new materials coating for the controlled immobilization of proteins whose use in biotechnological applications appears to be rewarding.

  4. Acute toxicity of peracetic acid (PAA) to fish

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA; also called peroxyacetic acid) is a promising new aquatic disinfectant that has also been used to treat parasites and fungus. It is registered with the U.S. Environmental Protection Agency (EPA) as an antimicrobial compound approved for indoor use on hard, non-porous surfaces. T...

  5. Relevance of nonfunctional linear polyacrylic acid for the biodegradation of superabsorbent polymer in soils.

    PubMed

    Bai, Mo; Wilske, Burkhard; Buegger, Franz; Esperschütz, Jürgen; Bach, Martin; Frede, Hans-Georg; Breuer, Lutz

    2015-04-01

    Biodegradability is a desired characteristic for synthetic soil amendments. Cross-linked polyacrylic acid (PAA) is a synthetic superabsorbent used to increase the water availability for plant growth in soils. About 4% within products of cross-linked PAA remains as linear polyacrylic acid (PAAlinear). PAAlinear has no superabsorbent function but may contribute to the apparent biodegradation of the overall product. This is the first study that shows specifically the biodegradation of PAAlinear in agricultural soil. Two (13)C-labeled PAAlinear of the average molecular weights of 530, 400, and 219,500 g mol(-1) were incubated in soil. Mineralization of PAAlinear was measured directly as the (13)CO2 efflux from incubation vessels using an automatic system, which is based on (13)C-sensitive wavelength-scanned cavity ring-down spectroscopy. After 149 days, the PAAlinear with the larger average molecular weight and chain length showed about half of the degradation (0.91% of the initial weight) of the smaller PAAlinear (1.85%). The difference in biodegradation was confirmed by the δ(13)C signature of the microbial biomass (δ(13)Cmic), which was significantly enriched in the samples with short PAAlinear (-13‰ against reference Vienna Pee Dee Belemnite,VPDB) as compared to those with long PAAlinear (-16‰ VPDB). In agreement with other polymer studies, the results suggest that the biodegradation of PAAlinear in soil is determined by the average molecular weight and occurs mainly at terminal sites. Most importantly, the study outlines that the size of PAA that escapes cross-linking can have a significant impact on the overall biodegradability of a PAA-based superabsorbent.

  6. A carbonate controlled-addition method for amorphous calcium carbonate spheres stabilized by poly(acrylic acid)s.

    PubMed

    Huang, Shu-Chen; Naka, Kensuke; Chujo, Yoshiki

    2007-11-20

    Stable amorphous calcium carbonate (ACC) composite particle with a size-controlled monodispersed sphere was obtained by a new simple carbonate controlled-addition method by using poly(acrylic acid) (PAA) (Mw = 5000), in which an aqueous ammonium carbonate solution was added into an aqueous solution of PAA and CaCl2 with a different time period. The obtained ACC composite products consist of about 50 wt % of ACC, 30 wt % of PAA, and H2O. Average particle sizes of the ACC spheres increased from (1.8 +/- 0.4) x 102 to (5.5 +/- 1.2) x 102 nm with an increase of the complexation time of the PAA-CaCl2 solution from 3 min to 24 h, respectively. The ACC formed from the complexation time for 3 min was stable for 10 days with gentle stirring as well as 3 months under a quiescent condition in the aqueous solution. Moreover, the ACC was also stable at 400 degrees C. Stability of the amorphous phase decreased with an increase of the complexation time of the PAA-CaCl2 solution. No ACC was obtained when the lower molar mass PAAs (Mw = 1200 and 2100) were used. In the higher molar mass case (Mw = 25 000), a mixture of the amorphous phase and vaterite and calcite crystalline product was produced. The present results demonstrate that the interaction and the reaction kinetics of the PAA-Ca2+-H2O complex play an important role in the mineralization of CaCO3.

  7. Acute toxicity of peracetic acid (PAA) to Ichthyophthirius multifiliis theronts

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) is an antimicrobial disinfectant used in agriculture, food processing and medical facilities. It has recently been suggested as a means to control infestations of Ichthyophthirius multifiliis. The purpose of this study was to determine the acute toxicity of two products contai...

  8. Behavior of Surface-Anchored Poly(acrylic acid) Brushes with Grafting Density Gradients on Solid Substrates: 1. Experiment

    SciTech Connect

    Wu,T.; Gong, P.; Szleifer, I.; Vicek, P.; Subr, V.; Genzer, J.

    2007-01-01

    We describe experiments pertaining to the formation of surface-anchored poly(acrylic acid) (PAA) brushes with a gradual variation of the PAA grafting densities on flat surfaces and provide detailed analysis of their properties. The PAA brush gradients are generated by first covering the substrate with a molecular gradient of the polymerization initiator, followed by the 'grafting from' polymerization of tert-butyl acrylate (tBA) from these substrate-bound initiator centers, and finally converting the PtBA into PAA. We use spectroscopic ellipsometry to measure the wet thickness of the grafted PAA chains in aqueous solutions at three different pH values (4, 5.8, and 10) and a series of ionic strengths (IS). Our measurements reveal that at low grafting densities, s, the wet thickness of the PAA brush (H) remains relatively constant, the polymers are in the mushroom regime. Beyond a certain value of s, the macromolecules enter the brush regime, where H increases with increasing s. For a given s, H exhibits a nonmonotonic behavior as a function of the IS. At large IS, the H is small because the charges along PAA are completely screened by the excess of the external salt. As IS decreases, the PAA enters the so-called salt brush (SB) regime, where H increases. At a certain value of IS, H reaches a maximum and then decreases again. The latter is a typical brush behavior in so-called osmotic brush (OB) regime. We provide detailed discussion of the behavior of the grafted PAA chains in the SB and OB regimes.

  9. A study on the swelling behavior of poly(acrylic acid) hydrogels obtained by electron beam crosslinking

    NASA Astrophysics Data System (ADS)

    Sheikh, N.; Jalili, L.; Anvari, F.

    2010-06-01

    Poly(acrylic acid) (PAA) hydrogels were prepared by using electron beam (EB) crosslinking of PAA homopolymer from its aqueous solutions. The swelling behavior of the hydrogels was studied as a function of the concentration of PAA solution, radiation dose, pH of the swelling medium and swelling time. Also the environmental pH effect on the water diffusion mode into hydrogels was investigated. These hydrogels clearly showed pH-sensitive swelling behavior with Fickian type of diffusion in the stomach-like pH medium (pH 1.3) and non-Fickian type in the intestine-like pH medium (pH 6.8).

  10. Poly(Acrylic Acid-b-Styrene) Amphiphilic Multiblock Copolymers as Building Blocks for the Assembly of Discrete Nanoparticles

    PubMed Central

    Greene, Anna C.; Zhu, Jiahua; Pochan, Darrin J.; Jia, Xinqiao; Kiick, Kristi L.

    2011-01-01

    In order to expand the utility of current polymeric micellar systems, we have developed amphiphilic multiblock copolymers containing alternating blocks of poly(acrylic acid) and poly(styrene). Heterotelechelic poly(tert-butyl acrylate-b-styrene) diblock copolymers containing an α-alkyne and an ω-azide were synthesized by atom transfer radical polymerization (ATRP), allowing control over the molecular weight while maintaining narrow polydispersity indices. The multiblock copolymers were constructed by copper-catalyzed azide-alkyne cycloaddition of azide-alkyne end functional diblock copolymers which were then characterized by 1H NMR, FT-IR and SEC. The tert-butyl moieties of the poly(tert-butyl acrylate-b-styrene) multiblock copolymers were easily removed to form the poly(acrylic acid-b-styrene) multiblock copolymer ((PAA-PS)9), which contained up to 9 diblock repeats. The amphiphilic multiblock (PAA-PS)9 (Mn = 73.3 kg/mol) was self-assembled by dissolution into tetrahydrofuran and extensive dialysis against deionized water for 4 days. The critical micelle concentration (CMC) for (PAA-PS)9 was determined by fluorescence spectroscopy using pyrene as a fluorescent probe and was found to be very low at 2 × 10-4 mg/mL. The (PAA-PS)9 multiblock was also analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter of the particles was found to be 11 nm. Discrete spherical particles were observed by TEM with an average particle diameter of 14 nm. The poly(acrylic acid) periphery of the spherical particles should allow for future conjugation of biomolecules. PMID:21552373

  11. Characterization of titanium dioxide nanoparticles modified with polyacrylic acid and H2O2 for use as a novel radiosensitizer.

    PubMed

    Morita, Kenta; Miyazaki, Serika; Numako, Chiya; Ikeno, Shinya; Sasaki, Ryohei; Nishimura, Yuya; Ogino, Chiaki; Kondo, Akihiko

    2016-12-01

    An induction of polyacrylic acid-modified titanium dioxide with hydrogen peroxide nanoparticles (PAA-TiO2/H2O2 NPs) to a tumor exerted a therapeutic enhancement of X-ray irradiation in our previous study. To understand the mechanism of the radiosensitizing effect of PAA-TiO2/H2O2 NPs, analytical observations that included DLS, FE-SEM, FT-IR, XAFS, and Raman spectrometry were performed. In addition, highly reactive oxygen species (hROS) which PAA-TiO2/H2O2 NPs produced with X-ray irradiation were quantified by using a chemiluminescence method and a EPR spin-trapping method. We found that PAA-TiO2/H2O2 NPs have almost the same characteristics as PAA-TiO2. Surprisingly, there were no significant differences in hROS generation. However, the existence of H2O2 was confirmed in PAA-TiO2/H2O2 NPs, because spontaneous hROS production was observed w/o X-ray irradiation. In addition, PAA-TiO2/H2O2 NPs had a curious characteristic whereby they absorbed H2O2 molecules and released them gradually into a liquid phase. Based on these results, the H2O2 was continuously released from PAA-TiO2/H2O2 NPs, and then released H2O2 assumed to be functioned indirectly as a radiosensitizing factor.

  12. Poly(acrylic acid)/polyethylene glycol hygrogel prepared by using gamma-ray irradiation for mucosa adhesion

    NASA Astrophysics Data System (ADS)

    Nho, Young-Chang; Park, Jong-Seok; Shin, Jung-Woong; Lim, Youn-Mook; Jeong, Sung-In; Shin, Young-Min; Gwon, Hui-Jeong; Khil, Myung-Seob; Lee, Deok-Won; Ahn, Sung-Jun

    2015-01-01

    A buccal delivery system provides a much milder environment for drug delivery compared to an oral delivery which presents a hostile environment for drugs, especially proteins and polypeptides, owing to acid hydrolysis. Local delivery in an oral cavity has particular applications in the treatment of toothaches, periodontal disease, and bacterial infections. Poly(acrylic acid) (PAA)-based hydrogels prepared using a chemical initiator have been attempted for a mucoadhesive system owing to their flexibility and excellent bioadhesion. In this experiment, PAA and polyethylene glycol (PEG) were selected to prepare using a radiation process a bioadhesive hydrogel for adhesion to mucosal surfaces. PAA and PEG were dissolved in purified water to prepare a homogeneous PAA/PEG solution, and the solution was then irradiated using an electron beam at dose up to 70 kGy to make the hydrogels. Their physical properties, such as gel percent, swelling percent, and adhesive strength to mucosal surfaces, were investigated. In this experiment, various amounts of PEG were incorporated into the PAA to enhance the mucoadhesive property of the hydrogels. The effect of the molecular weight of PEG on the mucoadhesion was also examined.

  13. Mechanism of poly(acrylic acid) acceleration of antithrombin inhibition of thrombin: implications for the design of novel heparin mimics.

    PubMed

    Monien, Bernhard H; Cheang, Kai I; Desai, Umesh R

    2005-08-11

    The bridging mechanism of antithrombin inhibition of thrombin is a dominant mechanism contributing a massive approximately 2500-fold acceleration in the reaction rate and is also a key reason for the clinical usage of heparin. Our recent study of the antithrombin-activating properties of a carboxylic acid-based polymer, poly(acrylic acid) (PAA), demonstrated a surprisingly high acceleration in thrombin inhibition (Monien, B. H.; Desai, U. R. J. Med. Chem. 2005, 48, 1269). To better understand this interesting phenomenon, we have studied the mechanism of PAA-dependent acceleration in antithrombin inhibition of thrombin. Competitive binding studies with low-affinity heparin and a heparin tetrasaccharide suggest that PAA binds antithrombin in both the pentasaccharide- and the extended heparin-binding sites, and these results are corroborated by molecular modeling. The salt-dependence of the K(D) of the PAA-antithrombin interaction shows the formation of five ionic interactions. In contrast, the contribution of nonionic forces is miniscule, resulting in an interaction that is significantly weaker than that observed for heparins. A bell-shaped profile of the observed rate constant for antithrombin inhibition of thrombin as a function of PAA concentration was observed, suggesting that inhibition proceeds through the "bridging" mechanism. The knowledge gained in this mechanistic study highlights important rules for the rational design of orally available heparin mimics.

  14. Drug release and washability of mucoadhesive gels based on sodium carboxymethylcellulose and polyacrylic acid.

    PubMed

    Rossi, S; Bonferoni, M C; Ferrari, F; Caramella, C

    1999-01-01

    This study investigated the relationship of the washability of gels based on two mucoadhesive polymers (sodium carboxymethylcellulose [NaCMC] and polyacrylic acid [PAA]) and their mixtures to their physical properties such as consistency and hydration/dissolution. The mucoadhesive properties of the two polymers and the effect of mucus-polymer interaction on gel washability at the mucoadhesive interface were also investigated using mixtures of PAA and NaCMC gels with increasing mucin amounts. Release and wash-away properties of the gels were assessed by means of a simultaneous release and wash-away test, whereas the consistency and hydration/dissolution properties of the gels were investigated by rheological analysis (viscosity and dynamic viscoelastic tests) and liquid uptake measurements, respectively. The results showed that PAA was characterized by lower release and wash-away properties than those of NaCMC. Mixing of two gels at different ratios allowed modulation of the release and wash-away properties. A relationship between washability and hydration/dissolution properties was found. Gel consistency by itself did not always provide a complete explanation of the wash-away process. The two polymers investigated showed different rheological interaction properties with mucin. Depending on the extent of such interaction, gel-mucin mixture had hydration/dissolution and washability properties that were quite different with respect to the initial gel.

  15. Elaboration, characterization and application of polysulfone and polyacrylic acid blends as ultrafiltration membranes for removal of some heavy metals from water.

    PubMed

    Mbareck, Chamekh; Nguyen, Quang Trong; Alaoui, Ouafa Tahiri; Barillier, Daniel

    2009-11-15

    Polysulfone (PSf)/polyacrylic acid ultrafiltration (PSf/PAA) membranes were prepared from a polymer blend in dimethylformamide by coagulation in water according to the wet phase inversion method. Immobilization of water-soluble PAA within the non-soluble PSf matrix was proven by the increase of ion exchange capacity and the intensity of the carboxyl groups' peak with the increase of PAA content as shown by Fourier transform infrared spectra. These results lead to consider that PSf and PAA form a semi-interpenetrating polymer networks. The obtained membranes showed a decrease of mean surface-pore sizes, the overall porosity and the hydraulic permeability with the increase in PAA content. Such results were imputed to the morphologic modifications of PSf film with the immobilization of increasing PAA amount. PSf/PAA membranes showed high lead, cadmium and chromium rejection which reaches 100% at pH superior to 5.7 and a low rejection at low pH. Moreover, the heavy metal rejection decreases with feed solution concentration and applied pressure increases. These behaviors were attributed to the role of carboxylic groups in ion exchange or complexation. As a matter of fact, the strong lead ion-PAA interactions were revealed by the scanning electron microscopy with energy dispersive X-rays (SEM-EDX).

  16. Simultaneous determination of norepinephrine, uric acid, and ascorbic acid at a screen printed carbon electrode modified with polyacrylic acid-coated multi-wall carbon nanotubes.

    PubMed

    Huang, Shih-Hung; Liao, Hsiu-Hsien; Chen, Dong-Hwang

    2010-06-15

    A screen printed carbon electrode (SPCE) modified with polyacrylic acid-coated multi-wall carbon nanotubes (PAA-MWCNTs) has been prepared by the dispersion of MWCNTs in PAA aqueous solution via sonication and the followed drop-coating for the simultaneous determination of norepinephrine (NE), uric acid (UA), and ascorbic acid (AA). The presence of PAA inhibited the adsorption of AA owing to the electrostatic repulsion, but was favorable for the affinity adsorption of NE and UA via the ion exchange and hydrogen bonding mechanisms, respectively. This led to the decrease in the oxidation potential of AA and the significantly enhanced oxidation peak currents of NE and UA at the PAA-MWCNTs/SPCE. By cyclic voltammetry and differential pulse voltammetry, the oxidation potentials of NE, UA, and AA at the PAA-MWCNTs/SPCE in a ternary mixture were found to be well resolved so that their simultaneous determination could be achieved. Furthermore, the interaction of NE, UA, and AA with PAA accounted for their electrochemical responses at different pH values. Also, the effect of pH revealed that the oxidation of NE, UA, and AA at the PAA-MWCNTs/SPCE all involved the transfer of two electrons. In addition, by differential pulse voltammetry, the linear dependence of peak current on the concentration was obtained in the ranges of 0-10, 0-30, and 100-1000 microM with the lowest detection limits of 0.131, 0.458, and 49.8 microM for NE, UA, and AA, respectively. Copyright 2010 Elsevier B.V. All rights reserved.

  17. [Biomimetic mineralization of a single-layer reconstituted type I collagen model induced by sodium tripolyphosphate and polyacrylic acid].

    PubMed

    Gu, Lisha; Mai, Sui; Qi, Yipin; Huang, Qi; Ling, Junqi

    2014-04-01

    To investigate the functions of sodium tripolyphosphate (STTP) and polyacrylic acid (PAA) in the process of collagen biomimetic mineralization. This would allow future applications to other collagen matrices such as bone collagen or 3-D collagen scaffolds. Glass cover slips and transmission electron microscopy (TEM) grids were coated with reconstituted typeIcollagen fibrils. Mineralization of the reconstituted collagens was demonstrated with scanning electron microscopy (SEM) and TEM using a Portland cement-containing resin composite and a phosphate-containing fluid in the presence of PAA and STTP. The rest were immersed in a biomimetic remineralization medium without PAA and/or STTP (control). In the presence of PAA and STTP in the mineralization medium, intrafibrillar mineralization based on the non-classical crystallisation pathway could be identified. Mineral phases were evident within the collagen fibrils as early as 12 h after the initially-formed amorphous calcium phosphate nanoprecursors were transformed into apatite nanocrystals. Collagens at 72 h were heavily mineralized with periodically arranged intrafibrillar apatite platelets. Conversely, only large mineral spheres with no preferred association with collagen fibrils were observed in the absence of biomimetic analogues in the medium (control). Intrafibrillar apatite deposition can be achieved via biomimetic mineralization system containing PAA and STTP when amorphous calcium phosphate precursor is stabilized.

  18. The Fouling of Zirconium(IV) Hydrous Oxide–Polyacrylate Dynamically Formed Membranes during the Nanofiltration of Lactic Acid Solutions

    PubMed Central

    Polom, Ewa

    2013-01-01

    The results of investigations of flux decline during nanofiltration (NF) of lactic acid solutions using dynamically formed zirconium(IV) hydrous oxide/polyacrylate membranes (Zr(IV)/PAA) under conditions resulting in low and high lactic acid rejection are reported. The experimental permeate flux versus time curves were analyzed in the frame of resistance in a series model with the aim of developing the characteristic of resistances. Analysis of experimental data and results of calculations showed that the reduction of fouling effects in the investigated system could be achieved due to appropriate hydrodynamic process conditions and regular rinsing with deionized water. PMID:24957066

  19. The Fouling of Zirconium(IV) Hydrous Oxide-Polyacrylate Dynamically Formed Membranes during the Nanofiltration of Lactic Acid Solutions.

    PubMed

    Polom, Ewa

    2013-12-10

    The results of investigations of flux decline during nanofiltration (NF) of lactic acid solutions using dynamically formed zirconium(IV) hydrous oxide/polyacrylate membranes (Zr(IV)/PAA) under conditions resulting in low and high lactic acid rejection are reported. The experimental permeate flux versus time curves were analyzed in the frame of resistance in a series model with the aim of developing the characteristic of resistances. Analysis of experimental data and results of calculations showed that the reduction of fouling effects in the investigated system could be achieved due to appropriate hydrodynamic process conditions and regular rinsing with deionized water.

  20. Effect of solution pH and ionic strength on the stability of poly(acrylic acid)-encapsulated multiwalled carbon nanotubes aqueous dispersion and its application for NADH sensor.

    PubMed

    Liu, Aihua; Watanabe, Takashi; Honma, Itaru; Wang, Jin; Zhou, Haoshen

    2006-12-15

    The optimal conditions to prepare water-soluble, stable poly(acrylic acid)-wrapped multiwalled carbon nanotubes (PAA-MWNTs) complex is presented. PAA-MWNTs shows high stability within weak acid to weak basic pH condition. The complex also shows good endurance to moderate ionic strengths in the buffer solution. The PAA-MWNTs complex film-covered electrode demonstrates stable, excellent electrocatalytic activity to oxidize NADH, which makes it possible to prepare NADH sensor at a low potential of approximately 0.13 V (versus Ag/AgCl) with the linear range of 4-100 microM by differential pulse voltammetry.

  1. Cisplatin-incorporated nanoparticles of poly(acrylic acid-co-methyl methacrylate) copolymer.

    PubMed

    Lee, Kyung Dong; Jeong, Young-Il; Kim, Da Hye; Lim, Gyun-Taek; Choi, Ki-Choon

    2013-01-01

    Although cisplatin is extensively used in the clinical field, its intrinsic toxicity limits its clinical use. We investigated nanoparticle formations of poly(acrylic acid-co-methyl methacrylate) (PAA-MMA) incorporating cisplatin and their antitumor activity in vitro and in vivo. Cisplatin-incorporated nanoparticles were prepared through the ion-complex formation between acrylic acid and cisplatin. The anticancer activity of cisplatin-incorporated nanoparticles was assessed with CT26 colorectal carcinoma cells. Cisplatin-incorporated nanoparticles have small particle sizes of less than 200 nm with spherical shapes. Drug content was increased according to the increase of the feeding amount of cisplatin and acrylic acid content in the copolymer. The higher acrylic acid content in the copolymer induced increase of particle size and decrease of zeta potential. Cisplatin-incorporated nanoparticles showed a similar growth-inhibitory effect against CT26 tumor cells in vitro. However, cisplatin-incorporated nanoparticles showed improved antitumor activity against an animal tumor xenograft model. We suggest that PAA-MMA nanoparticles incorporating cisplatin are promising carriers for an antitumor drug-delivery system.

  2. Characterization of bioactive RGD peptide immobilized onto poly(acrylic acid) thin films by plasma polymerization

    NASA Astrophysics Data System (ADS)

    Seo, Hyun Suk; Ko, Yeong Mu; Shim, Jae Won; Lim, Yun Kyong; Kook, Joong-Ki; Cho, Dong-Lyun; Kim, Byung Hoon

    2010-11-01

    Plasma surface modification can be used to improve the surface properties of commercial pure Ti by creating functional groups to produce bioactive materials with different surface topography. In this study, a titanium surface was modified with acrylic acid (AA) using a plasma treatment and immobilized with bioactive arginine-glycine-aspartic acid (RGD) peptide, which may accelerate the tissue integration of bone implants. Both terminals containing the -NH2 of RGD peptide sequence and -COOH of poly(acrylic acid) (PAA) thin film were combined with a covalent bond in the presence of 1-ethyl-3-3-dimethylaminopropyl carbodiimide (EDC). The chemical structure and morphology of AA film and RGD immobilized surface were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All chemical analysis showed full coverage of the Ti substrate with the PAA thin film containing COOH groups and the RGD peptide. The MC3T3-E1 cells were cultured on each specimen, and the cell alkaline phosphatase (ALP) activity were examined. The surface-immobilized RGD peptide has a significantly increased the ALP activity of MC3T3-E1 cells. These results suggest that the RGD peptide immobilization on the titanium surface has an effect on osteoblastic differentiation of MC3T3-E1 cells and potential use in osteo-conductive bone implants.

  3. Tunable single-walled carbon nanotube microstructure in the liquid and solid states using poly(acrylic acid).

    PubMed

    Grunlan, Jaime C; Liu, Lei; Kim, Yeon Seok

    2006-05-01

    Poly(acrylic acid) is shown to control the level of SWNT dispersion in aqueous mixtures and the state of dispersion in a solid composite. At low pH, PAA-stabilized suspensions containing 0.1 wt % SWNT have a waterlike viscosity, but this mixture thickens as the pH is raised. This behavior is reversed when pH is again lowered. Changing pH varies the SWNT microstructure between aggregated and well-exfoliated states, as evidenced by electron microscopy and electrical conductivity measurements.

  4. Polyacrylic acid grafted kaolinite via a facile ‘grafting to’ approach based on heterogeneous esterification and its adsorption for Cu2+

    NASA Astrophysics Data System (ADS)

    Zhao, Ping; Zhou, Qi; Yan, Chunjie; Luo, Wenjun

    2017-03-01

    Kaolinite (KLN) was successfully decorated by polyacrylic acid (PAA) brushes via a facile ‘one-step’ manner in this study. This process was achieved by heterogeneous esterification between carboxyl on the PAA chains and hydroxyl on the KLN in the presence of Al3+ as catalyst. The prepared composite (denoted as PAA-g-KLN) was characterized by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction pattern (XRD), Field emission scanning electron microscopy (FE-SEM) and thermogravimetry (TG) to confirm the successful grafting of PAA brushes on the surface of KLN. Subsequently, the PAA-g-KLN was used as adsorbent for the removal of Cu2+ from wastewater. Due to the introduction of abundant and highly accessible carboxyl groups on the surface of kaolinite, PAA-g-KLN exhibited an enhanced adsorption performance than raw kaolinite, which could be up to 32.45 mg·g‑1 at 45 °C with a fast adsorption kinetic. Theoretical models analysis revealed that Langmuir isotherm model and the pseudo second-order model were more suitable for well elucidation of the experimental data. In addition, the regeneration experiment showed that the PAA-g-KLN could still keep a satisfactory adsorption capacity (>65%) by being reused for 6 consecutive cycles. The study provides an easy and rapid method for surface polyelectrolyte modification on inorganic mineral as a promising adsorbent to remove Cu2+ from aqueous solution.

  5. A quick responding quartz crystal microbalance sensor array based on molecular imprinted polyacrylic acids coating for selective identification of aldehydes in body odor.

    PubMed

    Jha, Sunil K; Hayashi, Kenshi

    2015-03-01

    In present work, a novel quartz crystal microbalance (QCM) sensor array has been developed for prompt identification of primary aldehydes in human body odor. Molecularly imprinted polymers (MIP) are prepared using the polyacrylic acid (PAA) polymer matrix and three organic acids (propenoic acid, hexanoic acid and octanoic acid) as template molecules, and utilized as QCM surface coating layer. The performance of MIP films is characterized by 4-element QCM sensor array (three coated with MIP layers and one with pure PAA for reference) dynamic and static responses to target aldehydes: hexanal, heptanal, and nonanal in single, binary, and tertiary mixtures at distinct concentrations. The target aldehydes were selected subsequent to characterization of body odor samples with solid phase-micro extraction gas chromatography mass spectrometer (SPME-GC-MS). The hexanoic acid and octanoic acid imprinted PAA exhibit fast response, and better sensitivity, selectivity and reproducibility than the propenoic acid, and non-imprinted PAA in array. The response time and recovery time for hexanoic acid imprinted PAA are obtained as 5 s and 12 s respectively to typical concentrations of binary and tertiary mixtures of aldehydes using the static response. Dynamic sensor array response matrix has been processed with principal component analysis (PCA) for visual, and support vector machine (SVM) classifier for quantitative identification of target odors. Aldehyde odors were identified successfully in principal component (PC) space. SVM classifier results maximum recognition rate 79% for three classes of binary odors and 83% including single, binary, and tertiary odor classes in 3-fold cross validation.

  6. Carbonate minerals in porous media decrease mobility of polyacrylic acid modified zero-valent iron nanoparticles used for groundwater remediation.

    PubMed

    Laumann, Susanne; Micić, Vesna; Lowry, Gregory V; Hofmann, Thilo

    2013-08-01

    The limited transport of nanoscale zero-valent iron (nZVI) in porous media is a major obstacle to its widespread application for in situ groundwater remediation. Previous studies on nZVI transport have mainly been carried out in quartz porous media. The effect of carbonate minerals, which often predominate in aquifers, has not been evaluated to date. This study assessed the influence of the carbonate minerals in porous media on the transport of polyacrylic acid modified nZVI (PAA-nZVI). Increasing the proportion of carbonate sand in the porous media resulted in less transport of PAA-nZVI. Predicted travel distances were reduced to a few centimeters in pure carbonate sand compared to approximately 1.6 m in quartz sand. Transport modeling showed that the attachment efficiency and deposition rate coefficient increased linearly with increasing proportion of carbonate sand. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Radiation preparation of drug carriers based polyacrylic acid (PAAc) using poly(vinyl pyrrolidone) (PVP) as a template polymer

    NASA Astrophysics Data System (ADS)

    Abd El-Rehim, H. A.; Hegazy, E. A.; Khalil, F. H.; Hamed, N. A.

    2007-01-01

    The present study deals with the radiation synthesis of stimuli response hydrophilic polymers from polyacrylic acid (PAAc). To maintain the property of PAAc and control the water swellibility for its application as a drug delivery system, radiation polymerization of AAc in the presence of poly(vinyl pyrrolidone) (PVP) as a template polymer was carried out. Characterization of the prepared PAA/PVP inter-polymer complex was investigated by determining gel content, swelling property, hydrogel microstructure and the release rate of caffeine as a model drug. The release rate of caffeine from the PAA/PVP inter-polymer complexes showed pH-dependency, and seemed to be mainly controlled by the dissolution rate of the complex above a p Ka of PAAc. The prepared inter-polymer complex could be used for application as drug carriers.

  8. Interactions of sodium montmorillonite with poly(acrylic acid).

    PubMed

    Tran, Nguyen H; Dennis, Gary R; Milev, Adriyan S; Kannangara, G S Kamali; Wilson, Michael A; Lamb, Robert N

    2005-10-15

    The chemical-structural modifications of the natural clay sodium montmorillonite during interaction with poly(acrylic acid) were studied mainly by X-ray photoemission spectroscopy. Samples of modified montmorillonite were prepared from the reaction of sodium montmorillonite ( approximately 0.5 g) and an aqueous solution of poly(acrylic acid) (pH approximately 1.8, 50 g) at varying temperatures. X-ray diffraction indicated that the montmorillonite interlayer space ( approximately 13 A), formed by regular stacking of the silicate layers (dimension approximately 1x1000 nm), expanded to approximately 16 A as the reaction was carried out at room temperature and at 30 degrees C. At 60 degrees C, the interlayer space further expanded to approximately 20 A. The results of X-ray photoemission spectroscopy indicated that poly(acrylic acid) molecules exchange sodium ions on the surface of the silicate layers. These combined results allowed development of a reaction model that explains the dependency of the interlayer expansion with temperature. Information concerning the surface chemical reactions and systematic increases in the interlayer distances is particularly useful if montmorillonite and poly(acrylic acid) are to be used for formation of nanocomposite materials.

  9. High quality polyacrylic acid modified multifunction luminescent nanorods for tri-modality bioimaging, in vivo long-lasting tracking and biodistribution

    NASA Astrophysics Data System (ADS)

    Yi, Zhigao; Lu, Wei; Liu, Hongrong; Zeng, Songjun

    2014-12-01

    Polyacrylic acid (PAA) modified NaYF4:Gd/Yb/Er upconversion nanorods (denoted as PAA-UCNRs) are demonstrated for tri-modal upconversion (UC) optical, computed X-ray tomography (CT), and magnetic resonance imaging (MRI). The hydrophilic PAA-UCNRs were obtained from hydrophobic oleic acid (OA) capped UCNRs (denoted as OA-UCNRs) using a ligand exchange method. The as-prepared UCNRs with a hexagonal phase structure present high monodispersity. These PAA-UCNRs are successfully used as ideal probes for in vivo UC luminescence bioimaging and synergistic X-ray and UC bioimaging. Moreover, X-ray CT imaging reveals that PAA-UCNRs can act as contrast agents for improved detection of the liver and spleen. In addition, a significant signal enhancement in the liver is observed in in vivo MRI, indicating that PAA-UCNRs are ideal T1-weighted MRI agents. More importantly, in vivo long-term tracking based on these PAA-UCNRs in the live mice and the corresponding ex vivo bioimaging of isolated organs also verify the translocation of PAA-UCNRs from the liver to the spleen, and the observed intense UC signals from the feces reveal the biliary excretion mechanism of these UCNRs. These findings contribute to understanding of the translocation and potential route for excretion of PAA-UCNRs, which can provide an important guide for the diagnosis and detection of diseases based on these UCNRs.Polyacrylic acid (PAA) modified NaYF4:Gd/Yb/Er upconversion nanorods (denoted as PAA-UCNRs) are demonstrated for tri-modal upconversion (UC) optical, computed X-ray tomography (CT), and magnetic resonance imaging (MRI). The hydrophilic PAA-UCNRs were obtained from hydrophobic oleic acid (OA) capped UCNRs (denoted as OA-UCNRs) using a ligand exchange method. The as-prepared UCNRs with a hexagonal phase structure present high monodispersity. These PAA-UCNRs are successfully used as ideal probes for in vivo UC luminescence bioimaging and synergistic X-ray and UC bioimaging. Moreover, X-ray CT imaging

  10. Polyacrylic acid brushes grafted from P(St-AA)/Fe3O4 composite microspheres via ARGET-ATRP in aqueous solution for protein immobilization.

    PubMed

    Xie, Liqin; Lan, Fang; Li, Wenliao; Liu, Ziyao; Ma, Shaohua; Yang, Qi; Wu, Yao; Gu, Zhongwei

    2014-11-01

    Recently, the atom transfer radical polymerization (ATRP) of acrylic monomers in many reaction systems has been successfully accomplished. However, its application in aqueous solution is still a challenging task. In this work, polyacrylic acid (PAA) brushes with tunable length were directly grafted from P(St-AA)/Fe3O4 composite microspheres in aqueous solution via an improved method, activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP). This reaction was carried out in environment-friendly solvent. As well, this method overcame the sensitivity of the catalyst. Due to the strong coordination interaction of carboxyl groups, PAA brushes were employed for immobilizing gold nanoparticles, which were prepared via the in situ reduction of chloroauric acid. The PAA brushes modified magnetic composite microspheres decorating with gold nanoparticles were efficient for specific immobilization and separation of bovine serum albumin (BSA) from aqueous solution under the external magnetic field. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Interactions between lead-zirconate titanate, polyacrylic acid, and polyvinyl butyral in ethanol and their influence on electrophoretic deposition behavior.

    PubMed

    Kuscer, Danjela; Bakarič, Tina; Kozlevčar, Bojan; Kosec, Marija

    2013-02-14

    Electrophoretic deposition (EPD) is an attractive method for the fabrication of a few tens of micrometer-thick piezoelectric layers on complex-shape substrates that are used for manufacturing high-frequency transducers. Niobium-doped lead-zirconate titanate (PZT Nb) particles were stabilized in ethanol using poly(acrylic acid) (PAA). With Fourier-transform infrared spectroscopy (FT-IR), we found that the deprotonated carboxylic group from the PAA is coordinated with the metal in the perovskite PZT Nb structure, resulting in a stable ethanol-based suspension. The hydroxyl group from the polyvinyl butyral added into the suspension to prevent the formation of cracks in the as-deposited layer did not interact with the PAA-covered PZT Nb particles. PVB acts as a free polymer in ethanol-based suspensions. The electrophoretic deposition of micro- and nanometer-sized PZT Nb particles from ethanol-based suspensions onto electroded alumina substrates was attempted in order to obtain uniform, crack-free deposits. The interactions between the PZT Nb particles, the PAA, and the PVB in ethanol will be discussed and related to the properties of the suspensions, the deposition yield and the morphology of the as-deposited PZT Nb thick film.

  12. Layer-by-layer structured films of TiO2 nanoparticles and poly(acrylic acid) on electrospun nanofibres

    NASA Astrophysics Data System (ADS)

    Ding, Bin; Kim, Jinho; Kimura, Eiji; Shiratori, Seimei

    2004-08-01

    We report a new approach for fabricating layer-by-layer (LBL) structured ultrathin hybrid films on electrospun nanofibres. Oppositely charged anatase TiO2 nanoparticles and poly(acrylic acid) (PAA) were alternately deposited on the surface of negatively charged cellulose acetate (CA) nanofibres using the electrostatic LBL self-assembly technique. The fibrous mats were characterized by wide-angle x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller (BET) surface area techniques. The crystalline phase of anatase TiO2 remained unchanged in the resultant TiO2/PAA films coated on CA fibrous mats. Moreover, the TiO2/PAA film coated fibres showed rough surfaces with grains due to the deposition of aggregated TiO2 particles. The average diameter of the fibres increased from 344 to 584 nm and the BET surface area of the fibrous mats increased from 2.5 to 6.0 m2 g-1 after coating with five bilayers of TiO2/PAA films.

  13. Competitive sorption of Pb(II) and Zn(II) on polyacrylic acid-coated hydrated aluminum-oxide surfaces.

    PubMed

    Wang, Yingge; Michel, F Marc; Levard, Clement; Choi, Yong; Eng, Peter J; Brown, Gordon E

    2013-01-01

    Natural organic matter (NOM) often forms coatings on minerals. Such coatings are expected to affect metal-ion sorption due to abundant sorption sites in NOM and potential modifications to mineral surfaces, but such effects are poorly understood in complex multicomponent systems. Using poly(acrylic acid) (PAA), a simplified analog of NOM containing only carboxylic groups, Pb(II) and Zn(II) partitioning between PAA coatings and α-Al2O3 (1-102) and (0001) surfaces was investigated using long-period X-ray standing wave-florescence yield spectroscopy. In the single-metal-ion systems, PAA was the dominant sink for Pb(II) and Zn(II) for α-Al2O3(1-102) (63% and 69%, respectively, at 0.5 μM metal ions and pH 6.0). In equi-molar mixed-Pb(II)-Zn(II) systems, partitioning of both ions onto α-Al2O3(1-102) decreased compared with the single-metal-ion systems; however, Zn(II) decreased Pb(II) sorption to a greater extent than vice versa, suggesting that Zn(II) outcompeted Pb(II) for α-Al2O3(1-102) sorption sites. In contrast, >99% of both metal ions sorbed to PAA when equi-molar Pb(II) and Zn(II) were added simultaneously to PAA/α-Al2O3(0001). PAA outcompeted both α-Al2O3 surfaces for metal sorption but did not alter their intrinsic order of reactivity. This study suggests that single-metal-ion sorption results cannot be used to predict multimetal-ion sorption at NOM/metal-oxide interfaces when NOM is dominated by carboxylic groups.

  14. Physically cross-linked polymer binder based on poly(acrylic acid) and ion-conducting poly(ethylene glycol-co-benzimidazole) for silicon anodes

    NASA Astrophysics Data System (ADS)

    Lim, Sanghyun; Lee, Kukjoo; Shin, Inseop; Tron, Artur; Mun, Junyoung; Yim, Taeeun; Kim, Tae-Hyun

    2017-08-01

    The practical applications of Si electrodes in lithium-ion batteries are limited since they undergo large changes in volume during charge and discharge, and consequently become highly deteriorated. A novel binder system holding silicon particles together and preventing disintegration of the electrode during operation hence needs to be developed to enable reliable cycleability. In the current work, such a new polymer binder system, based on poly(acrylic acid) (PAA) and poly(ethylene glycol-co-benzimidazole) (PEGPBI), is developed for silicon anodes. The physical crosslinking using acid-base interactions between PAA and PBI, together with the ion-conducting PEG group, yields physical properties for the resulting PAA-PEGPBI-based anodes that are better than those of electrodes based on the currently available PAA binder, and yields good cell performances. A Si-based electrode with high loading levels of 1.0-1.3 mg cm-2 (0.7-0.91 Si mg cm-2) is reliably manufactured using specifically PAA-PEGPBI-2, which is made with 2 wt% of PEGPBI relative to PAA, and shows a very high capacity value of 1221 mAh g-1 at a rate of 0.5 C after 50 cycles, and a high capacity value of more than 1600 mAh g-1 at a high rate of 2 C.

  15. Disinfection of water in recirculating aquaculture systems with peracetic acid (PAA)

    USDA-ARS?s Scientific Manuscript database

    The disinfection behaviour of peracetic acid (PAA) in recirculating aquaculture systems (RAS) was investigated. Peracetic acid is a strong oxidizing agent found in various concentrations in different products. Three Wofasteril PAA products (E400 (c), Lspecical; AC 150) were tested in vitro for the...

  16. Nanoassembled thin film gas sensors. III. Sensitive detection of amine odors using TiO2/poly(acrylic acid) ultrathin film quartz crystal microbalance sensors.

    PubMed

    Lee, Seung-Woo; Takahara, Naoki; Korposh, Sergiy; Yang, Do-Hyeon; Toko, Kiyoshi; Kunitake, Toyoki

    2010-03-15

    Quartz crystal microbalance (QCM) gas sensors based on the alternate adsorption of TiO(2) and polyacrilic acid (PAA) were developed for the sensitive detection of amine odors. Individual TiO(2) gel layers could be regularly assembled with a thickness of approximately 0.3 nm by the gas-phase surface sol-gel process (GSSG). The thickness of the poly(acrylic acid) (PAA) layer is dependent on its molecular weight, showing different thicknesses of approximately 0.4 nm for PAA(25) (Mw 250,000) and 0.6-0.8 nm for PAA(400) (Mw 4,000,000). The QCM sensors showed a linear response to ammonia in the concentration range 0.3-15 ppm, depending on the deposition cycle of the alternate TiO(2)/PAA layer. The ammonia binding is based on the acid-base interaction to the free carboxylic acid groups of PAA and the limit of detection (LOD) of the 20-cycle TiO(2)/PAA(400) film was estimated to be 0.1 ppm when exposed to ammonia. The sensor response was very fast and stable in a wide relative humidity (rH) range of 30-70%, showing almost the same frequency changes at a given concentration of ammonia. Sensitivity to n-butylamine and ammonia was higher than to pyridine, which is owing to the difference of molecular weight and basicity of the amine analytes. The alternate TiO(2)/PAA(400) films have a highly effective ability to capture amine odors, and the ambient ammonia concentration of 15 ppm could be condensed up to approximately 20,000 ppm inside the films.

  17. Simultaneous voltammetric detection of dopamine and uric acid at their physiological level in the presence of ascorbic acid using poly(acrylic acid)-multiwalled carbon-nanotube composite-covered glassy-carbon electrode.

    PubMed

    Liu, Aihua; Honma, Itaru; Zhou, Haoshen

    2007-08-30

    The use of poly(acrylic acid) (PAA)-multiwalled carbon-nanotubes (MWNTs) composite-coated glassy-carbon disk electrode (GCE) (PAA-MWNTs/GCE) for the simultaneous determination of physiological level dopamine (DA) and uric acid (UA) in the presence of an excess of ascorbic acid (AA) in a pH 7.4 phosphate-buffered solution was proposed. PAA-MWNTs composite was prepared by mixing of MWNTs powder into 1 mg/ml PAA aqueous solution under sonication. GCE surface was modified with PAA-MWNTs film by casting. AA demonstrates no voltammetric peak at PAA-MWNTs/GCE. The PAA-MWNTs composite is of a high surface area and of affinity for DA and UA adsorption. DA exhibits greatly improved electron-transfer rate and is electro-catalyzed at PAA-MWNTs/GCE. Moreover, the electro-catalytic oxidation of UA at PAA-MWNTs/GCE is observed, which makes it possible to detect lower level UA. Therefore, the enhanced electrocatalytic currents for DA and UA were observed. The anodic peak currents at approximately 0.18 V and 0.35 V increase with the increasing concentrations of DA and UA, respectively, which correspond to the voltammetric peaks of DA and UA, respectively. The linear ranges are 40 nM to 3 microM DA and 0.3 microM to 10 microM UA in the presence of 0.3 mM AA. The lowest detection limits (S/N=3) were 20 nM DA and 110 nM UA.

  18. A Novel Route for Preparing Highly Stable Fe3O4 Fluid with Poly(Acrylic Acid) as Phase Transfer Ligand

    NASA Astrophysics Data System (ADS)

    Oanh, Vuong Thi Kim; Lam, Tran Dai; Thu, Vu Thi; Lu, Le Trong; Nam, Pham Hong; Tam, Le The; Manh, Do Hung; Phuc, Nguyen Xuan

    2016-08-01

    Highly stable Fe3O4 liquid was synthesized by thermal decomposition using poly(acrylic acid) (PAA) as a phase transfer ligand. The crystalline structure, morphology, and magnetic properties of the as-prepared samples were thoroughly characterized. Results demonstrated that the magnetic Fe3O4 nanomaterial was formed in liquid phase with a spinel single-phase structure, average size of 8-13 nm, and high saturation magnetization (up to 75 emu/g). The PAA-capped Fe3O4 nanoparticles displayed high stability over a wide pH range (from 4 to 7) in 300 mM salt solution. More importantly, the heat-generating capacity of the nanoparticle systems was quantified at a specific absorption rate (SAR) of 70.22 W/g, which is 35% higher than magnetic nanoparticles coated with sodium dodecyl sulfate (SDS). These findings suggest the potential application of PAA-coated magnetic nanoparticles in magnetic hyperthermia.

  19. Intrafibrillar mineralization of polyacrylic acid-bound collagen fibrils using a two-dimensional collagen model and Portland cement-based resins.

    PubMed

    Wu, Shiyu; Gu, Lisha; Huang, Zihua; Sun, Qiurong; Chen, Huimin; Ling, Junqi; Mai, Sui

    2017-02-01

    The biomimetic remineralization of apatite-depleted dentin is a potential method for enhancing the durability of resin-dentin bonding. To advance this strategy from its initial proof-of-concept design, we sought to investigate the characteristics of polyacrylic acid (PAA) adsorption to desorption from type I collagen and to test the mineralization ability of PAA-bound collagen. Portland cement and β-tricalcium phosphate (β-TCP) were homogenized with a hydrophilic resin blend to produce experimental resins. The collagen fibrils reconstituted on nickel (Ni) grids were mineralized using different methods: (i) group I consisted of collagen treated with Portland cement-based resin in simulated body fluid (SBF); (ii) group II consisted of PAA-bound collagen treated with Portland cement-based resin in SBF; and (iii) group III consisted of PAA-bound collagen treated with β-TCP-doped Portland cement-based resin in deionized water. Intrafibrillar mineralization was evaluated using transmission electron microscopy. We found that a carbonyl-associated peak at pH 3.0 increased as adsorption time increased, whereas a hydrogen bond-associated peak increased as desorption time increased. The experimental resins maintained an alkaline pH and the continuous release of calcium ions. Apatite was detected within PAA-bound collagen in groups II and III. Our results suggest that PAA-bound type I collagen fibrils can be mineralized using Portland cement-based resins.

  20. Poly(acrylic acid) conjugated hollow mesoporous carbon as a dual-stimuli triggered drug delivery system for chemo-photothermal synergistic therapy.

    PubMed

    Li, Xian; Liu, Chang; Wang, Shengyu; Jiao, Jian; Di, Donghua; Jiang, Tongying; Zhao, Qinfu; Wang, Siling

    2017-02-01

    In this work, we described the development of the redox and pH dual stimuli-responsive drug delivery system and combination of the chemotherapy and photothermal therapy for cancer treatment. The poly(acrylic acid) (PAA) was conjugated on the outlets of hollow mesoporous carbon (HMC) via disulfide bonds. PAA was used as a capping to block drug within the mesopores of HMC for its lots of favorable advantages, such as good biocompatibility, appropriate molecular weight to block the mesopores of HMC, extension of the blood circulation, and the improvement of the dispersity of the nano-carriers in physiological environment. The DOX loaded DOX/HMC-SS-PAA had a high drug loading amount up to 51.9%. The in vitro drug release results illustrated that DOX/HMC-SS-PAA showed redox and pH dual-responsive drug release, and the release rate could be further improved by the near infrared (NIR) irradiation. Cell viability experiment indicated that DOX/HMC-SS-PAA had a synergistic therapeutic effect by combination of chemotherapy and photothermal therapy. This work suggested that HMC-SS-PAA exhibited dual-responsive drug release property and could be used as a NIR-adsorbing drug delivery system for chemo-photothermal synergistic therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Phase-transfer behavior of cross-linked poly(acrylic acid) particles prepared by dispersion polymerization from ionic liquid to water.

    PubMed

    Minami, Hideto; Mizuta, Yusuke; Kimura, Akira

    2012-02-07

    The phase-transfer behavior of poly(acrylic acid) (PAA) particles from the hydrophobic ionic liquid N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)amide phase to the water phase in the particle state, which we reported previously, was examined in more detail. PAA particles were prepared in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([Bmim][TFSA]) and the organic solvent chloroform and were extracted. The transfer of PAA particles to water in the particle state was also observed in [Bmim][TFSA] systems. In contrast, the transfer phenomenon was not observed in the chloroform system. It was clarified that water/oil interfacial tension γ(wo) is an important parameter in the extraction of PAA in the particle state from the viewpoint of free energy. When the cationic surfactant tetradecyltrimethylammonium bromide, aqueous solution was used as the extraction medium, the PAA particles were extracted in the particle state from chloroform to water, in which γ(wo) became as low as that of the ionic liquid. This suggests that the phase-transfer phenomenon of PAA particles in the particle state was induced by the ionic liquid's unique property of low interfacial tension with water despite its high hydrophobic character.

  2. Nanostructure of a poly(acrylic acid) brush and its transition in the amphiphilic diblock copolymer monolayer on the water surface.

    PubMed

    Matsuoka, Hideki; Suetomi, Yoshiko; Kaewsaiha, Ploysai; Matsumoto, Kozo

    2009-12-15

    The nanostructure and its transition of in a poly(acrylic acid) (PAA) brush in the water surface monolayers of poly(hydrogenated isoprene)-b-poly(acrylic acid) with different block lengths and block ratios were investigated by X-ray reflectivity as a function of surface pressure (brush density) and salt concentration in the subphase. The PAA brush showed the same behavior after salt addition as did the poly(methacrylic acid) (PMAA) brush, which was investigated previously. The brush chains expanded and then shrunk after passing the maximum with increasing added salt concentration. This behavior could be explained by the change in electric charges on the PAA brush chains as was observed on the PMAA brush. The PAA brush chains showed a critical brush density, where there was a transition between the carpet layer only and carpet + brush layer structures, as did the PMAA and poly(styrene sulfonic acid) (PSS) brushes. The critical brush density was about 0.4 chains nm(-2), which was higher than that of the PSS brush, a strong acid brush, and was close to that of the PMAA brush, a weak acid brush. However, the critical brush density of the PAA brush was independent of the hydrophilic chain length whereas that of the PMAA brush decreased with increasing PMAA chain length. In addition, the PAA brush had a thicker carpet layer than the PSS and PMAA brushes. Hence, the mechanism of PAA brush formation was predicted to be different from that of not only the PSS brush (strong acid brush) but also the PMAA brush.

  3. Ion exchange selectivity for cross-linked polyacrylic acid

    NASA Technical Reports Server (NTRS)

    May, C. E.; Philipp, W. H.

    1983-01-01

    The ion separation factors for 21 common metal ions with cross-linked polyacrylic acid were determined as a function of pH and the percent of the cross-linked polyacrylic acid neutralized. The calcium ion was used as a reference. At a pH of 5 the decreasing order of affinity of the ions for the cross-linked polyacrylic acid was found to be: Hg++, Fe+++, Pb++, Cr+++, Cu++, Cd++, Al+++, Ag+, Zn++, Ni++, Mn++, Co++, Ca++, Sr++, Ba++, Mg++, K+, Rb+, Cs+, Na+, and Li+. Members of a chemical family exhibited similar selectivities. The Hg++ ion appeared to be about a million times more strongly bound than the alkali metal ions. The relative binding of most of the metal ions varied with pH; the very tightly and very weakly bound ions showed the largest variations with pH. The calcium ion-hydrogen ion equilibrium was perturbed very little by the presence of the other ions. The separation factors and selectivity coefficients are discussed in terms of equilibrium and thermodynamic significance.

  4. Sanitizing with peracetic acid (PAA)- An alternative treatment to use in aquaculture ...?

    USDA-ARS?s Scientific Manuscript database

    Because of the lack of approved treatments for fish disease, disinfectants were tested to treat fish pathogens. One of these substances is peracetic acid (PAA). PAA is an agent used for disinfection in aquaculture, but it must be investigated thoroughly in order to mitigate diseases without harmful ...

  5. Synthesis of polyacrylic-acid-based thermochromic polymers

    NASA Astrophysics Data System (ADS)

    Srivastava, Jyoti; Alam, Sarfaraz; Mathur, G. N.

    2003-10-01

    Smart materials respond to environmental stimuli with particular changes in some variables (for example temperature, pressure and electric field etc), for that reason they are often called responsive materials. In the present work, we have synthesized thermochromic polymer based on poly acrylic acid cobalt chloride (CoCl2) and phosphoric acid (H3PO4) that visually and reversibly changes color in the temperature range (70 - 130°C). These thermochromic materials can be used as visual sensors of temperature. Thermochromic polymers are based on polyacrylic acid and CoCl2 complex.

  6. Polyacrylic acid-coated cerium oxide nanoparticles: An oxidase mimic applied for colorimetric assay to organophosphorus pesticides.

    PubMed

    Zhang, Shi-Xiang; Xue, Shi-Fan; Deng, Jingjing; Zhang, Min; Shi, Guoyue; Zhou, Tianshu

    2016-11-15

    It is important and urgent to develop reliable and highly sensitive methods that can provide on-site and rapid detection of extensively used organophosphorus pesticides (OPs) for their neurotoxicity. In this study, we developed a novel colorimetric assay for the detection of OPs based on polyacrylic acid-coated cerium oxide nanoparticles (PAA-CeO2) as an oxidase mimic and OPs as inhibitors to suppress the activity of acetylcholinesterase (AChE). Firstly, highly dispersed PAA-CeO2 was prepared in aqueous solution, which could catalyze the oxidation of TMB to produce a color reaction from colorless to blue. And the enzyme of AChE was used to catalyze the substrate of acetylthiocholine (ATCh) to produce thiocholine (TCh). As a thiol-containing compound with reducibility, TCh can decrease the oxidation of TMB catalyzed by PAA-CeO2. Upon incubated with OPs, the enzymatic activity of AChE was inhibited to produce less TCh, resulting in more TMB catalytically oxidized by PAA-CeO2 to show an increasing blue color. The two representative OPs, dichlorvos and methyl-paraoxon, were tested using our proposed assay. The novel assay showed notable color change in a concentration-dependent manner, and as low as 8.62 ppb dichlorvos and 26.73 ppb methyl-paraoxon can be readily detected. Therefore, taking advantage of such oxidase-like activity of PAA-CeO2, our proposed colorimetric assay can potentially be a screening tool for the precise and rapid evaluation of the neurotoxicity of a wealth of OPs.

  7. Biodistribution of polyacrylic acid-coated iron oxide nanoparticles is associated with proinflammatory activation and liver toxicity.

    PubMed

    Couto, Diana; Freitas, Marisa; Costa, Vera Marisa; Chisté, Renan Campos; Almeida, Agostinho; Lopez-Quintela, M Arturo; Rivas, José; Freitas, Paulo; Silva, Paula; Carvalho, Félix; Fernandes, Eduarda

    2016-10-01

    Iron oxide nanoparticles (IONs) have physical and chemical properties that render them useful for several new biomedical applications. Still, so far, in vivo safety studies of IONs with coatings of biomedical interest are still scarce. The aim of this study, therefore, was to clarify the acute biological effects of polyacrylic acid (PAA)-coated IONs, by determining their biodistribution and their potential proinflammatory and toxic effects in CD-1 mice. The biodistribution of PAA-coated IONs in several organs (liver, spleen, kidneys, brain, heart, testes and lungs), the plasma cytokines, chemokine and aminotransferases levels, white blood cell count, oxidative stress parameters, adenosine triphosphate and histologic features of liver, spleen and kidneys were evaluated 24 h after a single acute (8, 20 or 50 mg kg(-1) ) intravenous administration of PAA-coated IONs in magnetite form. The obtained results showed that these IONs accumulate mainly in the liver and spleen and, to a lesser extent, in the lungs. Although our data showed that PAA-coated IONs do not cause severe organ damage, an inflammatory process was triggered in vivo, as evidenced by as evidenced by increased neutrophils and large lymphocytes in the differential blood count. Moreover, an accumulation of iron in macrophages of the liver and spleen was observed and hepatic lipid peroxidation was elicited, showing that the IONs are able to induce oxidative stress. The effects of these nanoparticles need to be further investigated regarding the mechanisms involved and the long-term consequences of intravenous administration of PAA-coated IONs. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Nanoclays reinforced glass ionomer cements: dispersion and interaction of polymer grade (PG) montmorillonite with poly(acrylic acid).

    PubMed

    Fareed, Muhammad A; Stamboulis, Artemis

    2014-01-01

    Montmorillonite nanoclays (PGV and PGN) were dispersed in poly(acrylic acid) (PAA) for utilization as reinforcing filler in glass ionomer cements (GICs). Chemical and physical interaction of PAA and nanoclay (PGV and PGN) was studied. PAA–PGV and PAA–PGN solutions were prepared in different weight percent loadings of PGV and PGN nanoclay (0.5-8.0 wt%) via exfoliation-adsorption method. Characterization was carried out by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and fourier transform infrared (FTIR) spectroscopy. XRD results of PAA–PGN demonstrated that the interlayer space expanded from 12.83 to 16.03 Å indicating intercalation whereas the absence of the peak at d(001) in PAA–PGV indicated exfoliation. XPS scans of PGV and PGN nanoclays depicted the main peak of O 1s photoelectron due to Si–O–M (M = Mg, Al, Fe) whereas, Si–O–Al linkages were identified by Si 2p or Si 2s and Al 2p or Al 2s peaks. The disappearance of the Na peak confirmed that PAA molecules exchanged sodium ions present on surface of silicate layers and significantly reduced the electrostatic van-der-Waals forces between silicate plates resulting in intercalation or exfoliation. FTIR spectra of PAA–nanoclay suspensions demonstrated the presence of a new peak at 1,019 cm(-1) associated with Si–O– stretching vibrations which increased with increasing nanoclays concentration. Information concerning the dispersion of nanoclay in PAA aqueous solutions, chemical reaction and increase interlayer space in montmorillonite nanoclay is particularly useful regarding dispersion and reinforcement of nanoclay in PAA.

  9. Transport of poly(acrylic acid) coated 2-line ferrihydrite nanoparticles in saturated aquifer sediments for environmental remediation

    NASA Astrophysics Data System (ADS)

    Xiang, Aishuang; Zhou, Sheng; Koel, Bruce E.; Jaffé, Peter R.

    2014-04-01

    Groundwater remediation using iron oxide and zero-valent iron nanoparticles (NPs) can be effective, but is limited in many applications due to the NP strong retention in groundwater-saturated porous media after injection, the passivation of the porous surface, and the high cost of nanomaterials versus macro scale iron. In this study, we investigated transport of bare and polymer-coated 2-line ferrihydrite NPs (30-300 nm) in saturated aquifer sediments. The influence of poly(acrylic acid) (PAA) polymer coatings was studied on the colloidal stability and transport in sediments packed column tests simulating groundwater flow in saturated sediments. In addition, the influence of calcium cations was investigated by transport measurements using sediments with calcium concentrations in the aqueous phase ranging from 0.5 (typical for most sediments) to 2 mM. Measurements were also made of zeta potential, hydrodynamic diameter, polymer adsorption and desorption properties, and bio-availability of PAA-coated NPs. We found that NP transport through the saturated aquifer sediments was improved by PAA coating and that the transport properties could be tuned by adjusting the polymer concentration. We further discovered that PAA coatings enhanced NP transport, compared to bare NPs, in all calcium-containing experiments tested, however, the presence of calcium always exhibited a negative effect on NP transport. In tests of bioavailability, the iron reduction rate of the coated and bare NPs by Geobacter sulfurreducens was the same, which shows that the PAA coating does not significantly reduce NP Fe(III) bioavailability. Our results demonstrate that much improved transport of iron oxide NP can be achieved in saturated aquifer sediments by introducing negatively charged polyelectrolytes and optimizing polymer concentrations, and furthermore, these coated NPs retain their bioavailability that is needed for applications in bio-environmental remediation.

  10. Poly(acrylic acid) modified calcium phosphate cements: the effect of the composition of the cement powder and of the molecular weight and concentration of the polymeric acid.

    PubMed

    Majekodunmi, A O; Deb, S

    2007-09-01

    Polymer modified calcium phosphate cements made with cement powders of varying tetracalcium phosphate [TTCP] content were prepared using two different molecular weight fractions of poly(acrylic acid) at four different concentrations. The ratio of the precursors (TTCP:DCPA) in the cement powder was found to influence the initial setting which decreased with increasing concentration of TTCP in the powder phase. It was also observed that cements derived from the higher molecular weight containing PAA yielded significantly (P < 0.05) shorter initial setting time (Ti) than cements containing the lower molecular weight, poly(acrylic acid) [GE7 PAA] The effect of the varying the TTCP content in the three different cement types PCPC-A, PCPC-B and PCPC-C showed that the trends of the compressive strength were specific to the concentration and molecular weight of the poly (acrylic acid). A 20% concentration of Glascol-E7 with a cement powder composed of an equimolar ratio of precursors (PCPC-B) resulted in optimal compressive strength within the range investigated. The TTCP content of the cement powder could also be varied to improve the diametral tensile strengths of the cements; the specific effects however, were again governed by both the concentration and molecular weight of the constituent poly (acrylic acid). The influence of TTCP on both the initial setting time and diametral tensile strength was related to the Ca (2+) ion concentration, which determined the rate and amount of cross-linking in the cement.

  11. Peracetic acid (PAA) disinfection of primary, secondary and tertiary treated municipal wastewaters.

    PubMed

    Koivunen, J; Heinonen-Tanski, H

    2005-11-01

    The efficiency of peracetic acid (PAA) disinfection against enteric bacteria and viruses in municipal wastewaters was studied in pilot-scale. Disinfection pilot-plant was fed with the primary or secondary effluent of Kuopio municipal wastewater treatment plant or tertiary effluent from the pilot-scale dissolved air flotation (DAF) unit. Disinfectant doses ranged from 2 to 7 mg/l PAA in the secondary and tertiary effluents, and from 5 to 15 mg/l PAA in the primary effluents. Disinfection contact times were 4-27 min. Disinfection of secondary and tertiary effluents with 2-7 mg/l PAA and 27 min contact time achieved around 3 log reductions of total coliforms (TC) and enterococci (EC). PAA disinfection also significantly improved the hygienic quality of the primary effluents: 10-15 mg/l PAA achieved 3-4 log reductions of TC and EC, 5 mg/l PAA resulting in below 2 log reductions. F-RNA coliphages were more resistant against the PAA disinfection and around 1 log reductions of these enteric viruses were typically achieved in the disinfection treatments of the primary, secondary and tertiary effluents. Most of the microbial reductions occurred during the first 4-18 min of contact time, depending on the PAA dose and microorganism. The PAA disinfection efficiency remained relatively constant in the secondary and tertiary effluents, despite of small changes of wastewater quality (COD, SS, turbidity, 253.7 nm transmittance) or temperature. The disinfection efficiency clearly decreased in the primary effluents with substantially higher microbial, organic matter and suspended solids concentrations. The results demonstrated that PAA could be a good alternative disinfection method for elimination of enteric microbes from different wastewaters.

  12. Biocompatibility of poly(ethylene glycol) and poly(acrylic acid) interpenetrating network hydrogel by intrastromal implantation in rabbit cornea.

    PubMed

    Zheng, Luo Luo; Vanchinathan, Vijay; Dalal, Roopa; Noolandi, Jaan; Waters, Dale J; Hartmann, Laura; Cochran, Jennifer R; Frank, Curtis W; Yu, Charles Q; Ta, Christopher N

    2015-10-01

    We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications.

  13. Biocompatibility of poly(ethylene glycol) and poly(acrylic acid) interpenetrating network hydrogel by intrastromal implantation in rabbit cornea

    PubMed Central

    Zheng, Luo Luo; Vanchinathan, Vijay; Dalal, Roopa; Noolandi, Jaan; Waters, Dale J.; Hartmann, Laura; Cochran, Jennifer R.; Frank, Curtis W.; Yu, Charles Q.; Ta, Christopher N.

    2015-01-01

    We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications. PMID:25778285

  14. Polymer coatings to passivate calcite from acid attack: polyacrylic acid and polyacrylonitrile.

    PubMed

    Thompson, Mary; Wilkins, Shelley J; Compton, Richard G; Viles, Heather A

    2003-04-01

    The extent of passivation of calcite toward dissolution by aqueous acids arising from polymeric coatings based on polyacrylic acid or polyacrylonitrile is evaluated using a channel flow cell technique with microdisc electrode detection. In situ passivation with polyacrylic acid leads to a reduction in the reactivity of calcite toward acid attack with a reduction in the rate constant by up to an order of magnitude compared with untreated calcite. Ex situ passivation with polyacrylic acid for 24 h results in good coverage of the calcite by the polymer but it is shown to erode from the surface when exposed to an aqueous acid solution. In contrast, polyacrylonitrile is demonstrated to form a regular coating after exposure for just 1 h and offers robust potent protection from aqueous acid attack.

  15. Transport in Porous Media of Poly(Acrylic Acid) Coated Ferrihydrite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Jaffe, P. R.; Xiang, A.; Koel, B. E.

    2012-12-01

    Augmentation of soils with iron to enhance biological processes such as uranium reduction via iron reducing bacteria, e.g., Geobacter sp., might be achieved via the injection of iron nanoparticles into the subsurface. The challenge is to make these nanoparticles transportable in the subsurface while not affecting the iron bioavailability. Poorly crystallized 2-line ferrihydrite iron oxide nanoparticles were synthesized and coated with different amounts of poly(acrylic acid) polymers (Na-PAA6K or Na-PAA140K). Analyses were then performed on these particles, including sorption/desorption of the polymer onto the iron nanoparticles, particle size, zeta potential, transport in sand and soil columns, and bioavailabity of the Fe(III) in the absence and presence of the coating to iron reducing organisms. Results showed that at pH values of environmental relevance, the zeta potential of the particles varied from about 3 mV (pH=8.2) for the non-coated particles to about -30 mV for the particles coated with the polymers to their highest sorption capacity. The coated particle diameter was shown to be in the range of 200 nm. Column transport experiments showed that for the highest polymer coating the nanoparticle breakthrough was virtually identical to that of bromide, while significant filtration was observed for particles with an intermediate coating, and complete particle removal via filtration was observed for the non-coated particles. These results held for sand as well as for soil, which had been previously characterized, from a field site at Rifle, CO. Bioavailability experiments showed no difference in the iron reduction rate between the untreated and treated nanoparticles. These results show that it is possible to manufacture iron nanoparticles to enhance biological iron reduction, and that the transport properties of these treated particles is tunable so that a desired retention in the porous medium can be achieved.

  16. Improved plant regeneration from wheat anther and barley microspore culture using phenylacetic acid (PAA).

    PubMed

    Ziauddin, A; Marsolais, A; Simion, E; Kasha, K J

    1992-09-01

    The effect of the auxin phenylacetic acid (PAA) on wheat anther and on barley anther/microspore culture was investigated. With PAA the induction response was not usually significantly different from controls but a significantly higher number of green plants were produced in wheat anther and barley microspore culture. For wheat anther culture 100 mg/L PAA was beneficial. For barley microspore culture the optimum levels were from 1 to 100 mg/L, depending on genotype. In barley anther culture there were no improvements using PAA. In wheat anther culture, 145 green plants/100 anthers were obtained with cultivar Veery'S', while the average response from twelve F1 hybrids in the breeding program was 332 green plants/100 anthers. At least 1000 green plants were obtained using isolated microspores from 100 anthers in barley cv. Igri. With cv. Bruce, regeneration occurred only when 100 mg/L PAA was used. The influence of PAA appears at the embryogenic phase of the culture system. The possible mechanisms by which PAA may improve regeneration are discussed.

  17. Optimal Parameter Determination for Tritiated Water Storage in Polyacrylic Networks

    SciTech Connect

    Postolache, C.; Matei, Lidia; Georgescu, Rodica; Ionita, Gh.

    2005-07-15

    Due to the remarkable capacity of water retaining, croslinked polyacrylic acids (PAA) represent an interesting alternative for tritiated water trapping. The study was developed on radiolytical processes in PAA:HTO systems derivated from irradiation of polymeric network by disintegration of tritium atoms from HTO. The aim of these studies is the identification of polymeric structures and optimal storage conditions.Sol and gel fractions were determinated by radiometrical methods using PAA labeled with 14-C at carboxylic groups and T at main chains of the polymer. Simulation of radiolytical processes was realized using {gamma} radiation field emitted by a irradiation source of 60-Co which ensures a maximum of absorbed dose rate of 3 kGy/h. Self-radiolytical effects were investigated using labeled PAA in HTO with great radioactive concentration (37-185 GBq/mL). The experiment suggests as optimum for HTO storage as tritium liquid wastes a 1:30 PAA:HTO swelling degree at 18.5-37 MBqL. HTO radioactive concentration.RES studies of radiolytical processes were also realized on dry polyacrylic acid (PAA) and polyacrylic based hydrogels irradiated and determined at 77 K. In the study we observed the effect of swelling capacity of hydrogel o the formation of free radicals.

  18. Efficient removal of malachite green dye using biodegradable graft copolymer derived from amylopectin and poly(acrylic acid).

    PubMed

    Sarkar, Amit Kumar; Pal, Aniruddha; Ghorai, Soumitra; Mandre, N R; Pal, Sagar

    2014-10-13

    This article reports on the application of a high performance biodegradable adsorbent based on amylopectin and poly(acrylic acid) (AP-g-PAA) for removal of toxic malachite green dye (MG) from aqueous solution. The graft copolymer has been synthesized and characterized using various techniques including FTIR, GPC, SEM and XRD analyses. Biodegradation study suggests that the co-polymer is biodegradable in nature. The adsorbent shows excellent potential (Qmax, 352.11 mg g(-1); 99.05% of MG has been removed within 30 min) for removal of MG from aqueous solution. It has been observed that point to zero charge (pzc) of graft copolymer plays significant role in adsorption efficacy. The adsorption kinetics and isotherm follow pseudo-second order and Langmuir isotherm models, respectively. Thermodynamics parameters suggest that the process of dye uptake is spontaneous. Finally desorption study shows excellent regeneration efficiency of adsorbent.

  19. Cell type-specific response to high intracellular loading of polyacrylic acid-coated magnetic nanoparticles

    PubMed Central

    Lojk, Jasna; Bregar, Vladimir B; Rajh, Maruša; Miš, Katarina; Kreft, Mateja Erdani; Pirkmajer, Sergej; Veranič, Peter; Pavlin, Mojca

    2015-01-01

    Magnetic nanoparticles (NPs) are a special type of NP with a ferromagnetic, electron-dense core that enables several applications such as cell tracking, hyperthermia, and magnetic separation, as well as multimodality. So far, superparamagnetic iron oxide NPs (SPIONs) are the only clinically approved type of metal oxide NPs, but cobalt ferrite NPs have properties suitable for biomedical applications as well. In this study, we analyzed the cellular responses to magnetic cobalt ferrite NPs coated with polyacrylic acid (PAA) in three cell types: Chinese Hamster Ovary (CHO), mouse melanoma (B16) cell line, and primary human myoblasts (MYO). We compared the internalization pathway, intracellular trafficking, and intracellular fate of our NPs using fluorescence and transmission electron microscopy (TEM) as well as quantified NP uptake and analyzed uptake dynamics. We determined cell viability after 24 or 96 hours’ exposure to increasing concentrations of NPs, and quantified the generation of reactive oxygen species (ROS) upon 24 and 48 hours’ exposure. Our NPs have been shown to readily enter and accumulate in cells in high quantities using the same two endocytic pathways; mostly by macropinocytosis and partially by clathrin-mediated endocytosis. The cell types differed in their uptake rate, the dynamics of intracellular trafficking, and the uptake capacity, as well as in their response to higher concentrations of internalized NPs. The observed differences in cell responses stress the importance of evaluation of NP–cell interactions on several different cell types for better prediction of possible toxic effects on different cell and tissue types in vivo. PMID:25733835

  20. Cell type-specific response to high intracellular loading of polyacrylic acid-coated magnetic nanoparticles.

    PubMed

    Lojk, Jasna; Bregar, Vladimir B; Rajh, Maruša; Miš, Katarina; Kreft, Mateja Erdani; Pirkmajer, Sergej; Veranič, Peter; Pavlin, Mojca

    2015-01-01

    Magnetic nanoparticles (NPs) are a special type of NP with a ferromagnetic, electron-dense core that enables several applications such as cell tracking, hyperthermia, and magnetic separation, as well as multimodality. So far, superparamagnetic iron oxide NPs (SPIONs) are the only clinically approved type of metal oxide NPs, but cobalt ferrite NPs have properties suitable for biomedical applications as well. In this study, we analyzed the cellular responses to magnetic cobalt ferrite NPs coated with polyacrylic acid (PAA) in three cell types: Chinese Hamster Ovary (CHO), mouse melanoma (B16) cell line, and primary human myoblasts (MYO). We compared the internalization pathway, intracellular trafficking, and intracellular fate of our NPs using fluorescence and transmission electron microscopy (TEM) as well as quantified NP uptake and analyzed uptake dynamics. We determined cell viability after 24 or 96 hours' exposure to increasing concentrations of NPs, and quantified the generation of reactive oxygen species (ROS) upon 24 and 48 hours' exposure. Our NPs have been shown to readily enter and accumulate in cells in high quantities using the same two endocytic pathways; mostly by macropinocytosis and partially by clathrin-mediated endocytosis. The cell types differed in their uptake rate, the dynamics of intracellular trafficking, and the uptake capacity, as well as in their response to higher concentrations of internalized NPs. The observed differences in cell responses stress the importance of evaluation of NP-cell interactions on several different cell types for better prediction of possible toxic effects on different cell and tissue types in vivo.

  1. Poly(acrylic acid) grafted montmorillonite as novel fillers for dental adhesives: synthesis, characterization and properties of the adhesive.

    PubMed

    Solhi, Laleh; Atai, Mohammad; Nodehi, Azizollah; Imani, Mohammad; Ghaemi, Azadeh; Khosravi, Kazem

    2012-04-01

    This work investigates the graft polymerization of acrylic acid onto nanoclay platelets to be utilized as reinforcing fillers in an experimental dental adhesive. Physical and mechanical properties of the adhesive and its shear bond strength to dentin are studied. The effect of the modification on the stability of the nanoparticle dispersion in the dilute adhesive is also investigated. Poly(acrylic acid) (PAA) was grafted onto the pristine Na-MMT nanoclay (Cloisite(®) Na(+)) through the free radical polymerization of acylic acid in an aqueous media. The resulting PAA-g-nanoclay was characterized using FTIR, TGA and X-ray diffraction (XRD). The modified nanoclays were added to an experimental dental adhesive in different concentrations and the morphology of the nanoclay layers in the photocured adhesive matrix was studied using TEM and XRD. Shear bond strength of the adhesives containing different filler contents was tested on the human premolar teeth. The stability of nanoclay dispersion in the dilute adhesive was also studied using a separation analyzer. The results were then statistically analyzed and compared. The results confirmed the grafting reaction and revealed a partially exfoliated structure for the PAA-g-nanoclay. Incorporation of 0.2 wt.% of the modified nanoclay into the experimental adhesive provided higher shear bond strength. The dispersion stability of the modified nanoparticles in the dilute adhesive was also enhanced more than 25 times. Incorporation of the modified particles as reinforcing fillers into the adhesive resulted in higher mechanical properties. The nanofiller containing bonding agent also showed higher shear bond strength due to the probable interaction of the carboxylic acid functional groups on the surface of the modified particles with hydroxyapatite of dentin. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. Interpolymer complexes of poly(acrylic acid) and chitosan: influence of the ionic hydrogel-forming medium.

    PubMed

    de la Torre, Paloma M; Torrado, Susana; Torrado, Santiago

    2003-04-01

    Non-covalent polyionic complexes were developed for localized antibiotic delivery in the stomach. Freeze-dried interpolymer complexes based on polyacrylic acid (PAA) and chitosan (CS) were prepared in a wide range of copolymer compositions by dissolving both polymers in acidic conditions. The influence of hydrogel-forming medium on the swelling and drug release was evaluated. The properties of these complexes were investigated by using scanning electron microscopy, dynamic swelling/eroding and release experiments in enzyme-free simulated gastric fluid (SGF). The electrostatic polymer/polymer interactions generate polyionic complexes with different porous structures. In a low pH environment, the separation of both polymer chains augmented as the amount of cationic and carboxilic groups increased within the network. However, the presence of higher amount of ions in the hydrogel-forming medium produced a network collapse, decreasing the maximum swelling ratio in SGF. PAA:CS:A (1:2.5:2)-1.75 M complexes released around 54% and 71% of the amoxicillin in 1 and 2 h, respectively, in acidic conditions. A faster drug release from this interpolymer complex was observed when the ionic strength of the hydrogel-forming medium increased. Complexes with a high amount of both polymer chains within the network, PAA:CS:A(2.5:5:2), showed a suitable amoxicillin release without being affected by an increased amount of ions in the hydrogel-forming medium. These freeze-dried interpolymer complexes could serve as potential candidates for amoxicillin delivery in an acidic enviroment. Copyright 2002 Elsevier Science Ltd.

  3. A new approach for the immobilization of poly(acrylic) acid as a chemically reactive cross-linker on the surface of poly(lactic) acid-based biomaterials.

    PubMed

    Stankevich, Ksenia S; Danilenko, Nadezhda V; Gadirov, Ruslan M; Goreninskii, Semen I; Tverdokhlebov, Sergei I; Filimonov, Victor D

    2017-02-01

    A new approach for the immobilization of poly(acrylic) acid (PAA) as a chemically reactive cross-linker on the surface of poly(lactic) acid-based (PLA) biomaterials is described. The proposed technique includes non-covalent attachment of a PAA layer to the surface of PLA-based biomaterial via biomaterial surface treatment with solvent/non-solvent mixture followed by the entrapment of PAA from its solution. Surface morphology and wettability of the obtained PLA-PAA composite materials were investigated by AFM and the sitting drop method respectively. The amount of the carboxyl groups on the composites surface was determined by using the fluorescent compounds (2-(5-aminobenzo[d]oxazol-2-yl)phenol (ABO) and its acyl derivative N-(2-(2-hydroxyphenyl)benzo[d]oxazol-5-yl)acetamide (AcABO)). It was shown that it is possible to obtain PLA-PAA composites with various surface relief and tunable wettability (57°, 62° and 66°). The capacity of the created PAA layer could be varied from 1.5nmol/cm(2) to 0.1μmol/cm(2) depending on the modification conditions. Additionally, using bovine serum albumin (BSA) it was demonstrated that such composites could be modified with proteins with high binding density (around 0.18nmol/cm(2)). Obtained fluoro-labeled PLA-PAA materials, as well as PLA-PAA composites themselves, are valuable since they can be used for biodegradable polymer implants tracking in living systems and as drug delivery systems. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. An examination of the rheological and mucoadhesive properties of poly(acrylic acid) organogels designed as platforms for local drug delivery to the oral cavity.

    PubMed

    Jones, David S; Muldoon, Brendan C O; Woolfson, A David; Sanderson, F Dominic

    2007-10-01

    This study examined the rheological/mucoadhesive properties of poly(acrylic acid) PAA organogels as platforms for drug delivery to the oral cavity. Organogels were prepared using PAA (3%, 5%, 10% w/w) dissolved in ethylene glycol (EG), propylene glycol (PG), 1,3-propylene glycol (1,3-PG), 1,5-propanediol (1,5-PD), polyethylene glycol 400 (PEG 400), or glycerol. All organogels exhibited pseudoplastic flow. The increase in storage (G') and loss (G'') moduli of organogels as a function of frequency was minimal, G'' was greater than G'' (at all frequencies), and the loss tangent <1, indicative of gel behavior. Organogels prepared using EG, PG, and 1,3-propanediol (1,3-PD) exhibited similar flow/viscoelastic properties. Enhanced rheological structuring was associated with organogels prepared using glycerol (in particular) and PEG 400 due to their interaction with adjacent carboxylic acid groups on each chain and on adjacent chains. All organogels (with the exception of 1,5-PD) exhibited greater network structure than aqueous PAA gels. Organogel mucoadhesion increased with polymer concentration. Greatest mucoadhesion was associated with glycerol-based formulations, whereas aqueous PAA gels exhibited the lowest mucoadhesion. The enhanced network structure and the excellent mucoadhesive properties of these organogels, both of which may be engineered through choice of polymer concentration/solvent type, may be clinically useful for the delivery of drugs to the oral cavity. (c) 2007 Wiley-Liss, Inc.

  5. Ultrasensitive determination of serum albumin using resonance light scattering based on ZnS-polyacrylic acid nanoparticles

    NASA Astrophysics Data System (ADS)

    Peng, Li; Li, Chunya; Xue, Hongbo; Zhan, Guoqing

    2010-05-01

    ZnS-polyacrylic acid (ZnS-PAA) was prepared by an in situ polymerization method using nano-ZnS as core in the presence of acrylic acid (AA), and ZnS-PAA nanoparticles was characterized by ultraviolet spectrometry (UV) and transmission electron microscopy (TEM). Based on the significant increase of the resonance light scattering (RLS) intensity with the interaction between nanoparticles and serum albumin, RLS method was developed for the sensitive determination of serum albumin (BSA and HSA). Under optimum conditions, the change of the intensity (Δ I) of the RLS spectra at λ = 392 nm was linearly proportional to the concentration of BSA and HSA. The linear range was 1-100 ng mL -1 for HSA and 1-120 ng mL -1 for BSA, and the limit of detection (LOD) was 0.4 ng mL -1 for HSA and 0.5 ng mL -1 for BSA. This method proved to be very sensitive, rapid, simple and tolerant of most interfering substances.

  6. Polyacrylic acids-bovine serum albumin complexation: Structure and dynamics.

    PubMed

    Othman, Mohamed; Aschi, Adel; Gharbi, Abdelhafidh

    2016-01-01

    The study of the mixture of BSA with polyacrylic acids at different masses versus pH allowed highlighting the existence of two regimes of weak and strong complexation. These complexes were studied in diluted regime concentration, by turbidimetry, dynamic light scattering (DLS), zeta-potential measurements and nuclear magnetic resonance (NMR). We have followed the pH effect on the structure and properties of the complex. This allowed refining the interpretation of the phase diagram and understanding the observed phenomena. The NMR measurements allowed probing the dynamics of the constituents versus the pH. The computational method was used to precisely determine the electrostatic potential of BSA and how the polyelectrolyte binds to it at different pH.

  7. Influence of air-abrasion executed with polyacrylic acid-Bioglass 45S5 on the bonding performance of a resin-modified glass ionomer cement.

    PubMed

    Sauro, Salvatore; Watson, Timothy F; Thompson, Ian; Toledano, Manuel; Nucci, Cesare; Banerjee, Avijit

    2012-04-01

    The aim of this study was to test the microtensile bond strength (μTBS), after 6 months of storage in PBS, of a resin-modified glass ionomer cement (RMGIC) bonded to dentine pretreated with Bioglass 45S5 (BAG) using various etching and air-abrasion techniques. The RMGIC (GC Fuji II LC) was applied onto differently treated dentine surfaces followed by light curing for 30 s. The specimens were cut into matchsticks with cross-sectional areas of 0.9 mm(2). The μTBS of the specimens was measured after 24 h or 6 months of storage in PBS and the results were statistically analysed using two-way anova and the Student-Newman-Keuls test (α = 0.05). Further RMCGIC-bonded dentine specimens were used for interfacial characterization, micropermeability, and nanoleakage analyses by confocal microscopy. The RMGIC-dentine interface layer showed no water absorption after 6 months of storage in PBS except for the interdiffusion layer of the silicon carbide (SiC)-abraded/polyacrylic acid (PAA)-etched bonded dentine. The RMGIC applied onto dentine air-abraded with BAG/H(2)O only or with BAG/PAA-fluid followed by etching procedures (10% PAA gel) showed no statistically significant reduction in μTBS after 6 months of storage in PBS. The abrasion procedures performed using BAG in combination with PAA might be a suitable strategy to enhance the bonding durability and the healing ability of RMGIC bonded to dentine.

  8. Poly(acrylic acid) modified lanthanide-doped GdVO4 hollow spheres for up-conversion cell imaging, MRI and pH-dependent drug release

    NASA Astrophysics Data System (ADS)

    Kang, Xiaojiao; Yang, Dongmei; Dai, Yunlu; Shang, Mengmeng; Cheng, Ziyong; Zhang, Xiao; Lian, Hongzhou; Ma, Ping'an; Lin, Jun

    2012-12-01

    In this study, multifunctional poly(acrylic acid) modified lanthanide-doped GdVO4 nanocomposites [PAA@GdVO4: Ln3+ (Ln = Yb/Er, Yb/Ho, Yb/Tm)] were constructed by filling PAA hydrogel into GdVO4 hollow spheres via photoinduced polymerization. The up-conversion (UC) emission colors (green, red and blue) can be tuned by changing the codopant compositions in the matrices. The composites have potential applications as bio-probes for cell imaging. Meanwhile, the hybrid spheres can act as T1 contrast agents for magnetic resonance imaging (MRI) owing to the existence of Gd3+ ions on the surface of composites. Due to the nature of PAA, DOX-loaded PAA@GdVO4:Yb3+/Er3+ system exhibits pH-dependent drug releasing kinetics. A lower pH offers a faster drug release rate. Such character makes the loaded DOX easily released at cancer cells. The cell uptake process of drug-loaded composites was observed by using confocal laser scanning microscopy (CLSM). The results indicate the potential application of the multifunctional composites as theragnostics (effective bimodal imaging probes and pH-responsive drug carriers).

  9. Nanostructure of Poly(Acrylic Acid) Adsorption Layer on the Surface of Activated Carbon Obtained from Residue After Supercritical Extraction of Hops

    NASA Astrophysics Data System (ADS)

    Wiśniewska, M.; Nosal-Wiercińska, A.; Ostolska, I.; Sternik, D.; Nowicki, P.; Pietrzak, R.; Bazan-Wozniak, A.; Goncharuk, O.

    2017-01-01

    The nanostructure of poly(acrylic acid) (PAA) adsorption layer on the surface of mesoporous-activated carbon HPA obtained by physical activation of residue after supercritical extraction of hops was characterized. This characterization has been done based on the analysis of determination of adsorbed polymer amount, surface charge density, and zeta potential of solid particles (without and in the PAA presence). The SEM, thermogravimetric, FTIR, and MS techniques have allowed one to examine the solid surface morphology and specify different kinds of HPA surface groups. The effects of solution pH, as well as polymer molecular weight and concentration, were studied. The obtained results indicated that the highest adsorption on the activated carbon surface was exhibited by PAA with lower molecular weight (i.e., 2000 Da) at pH 3. Under such conditions, polymeric adsorption layer is composed of nanosized PAA coils (slightly negatively charged) which are densely packed on the positive surface of HPA. Additionally, the adsorption of polymeric macromolecules into solid pores is possible.

  10. Poly(acrylic acid) modified lanthanide-doped GdVO4 hollow spheres for up-conversion cell imaging, MRI and pH-dependent drug release.

    PubMed

    Kang, Xiaojiao; Yang, Dongmei; Dai, Yunlu; Shang, Mengmeng; Cheng, Ziyong; Zhang, Xiao; Lian, Hongzhou; Ma, Ping'an; Lin, Jun

    2013-01-07

    In this study, multifunctional poly(acrylic acid) modified lanthanide-doped GdVO(4) nanocomposites [PAA@GdVO(4): Ln(3+) (Ln = Yb/Er, Yb/Ho, Yb/Tm)] were constructed by filling PAA hydrogel into GdVO(4) hollow spheres via photoinduced polymerization. The up-conversion (UC) emission colors (green, red and blue) can be tuned by changing the codopant compositions in the matrices. The composites have potential applications as bio-probes for cell imaging. Meanwhile, the hybrid spheres can act as T(1) contrast agents for magnetic resonance imaging (MRI) owing to the existence of Gd(3+) ions on the surface of composites. Due to the nature of PAA, DOX-loaded PAA@GdVO(4):Yb(3+)/Er(3+) system exhibits pH-dependent drug releasing kinetics. A lower pH offers a faster drug release rate. Such character makes the loaded DOX easily released at cancer cells. The cell uptake process of drug-loaded composites was observed by using confocal laser scanning microscopy (CLSM). The results indicate the potential application of the multifunctional composites as theragnostics (effective bimodal imaging probes and pH-responsive drug carriers).

  11. Improved Release of Celecoxib from High Drug Loading Amorphous Solid Dispersions Formulated with Polyacrylic Acid and Cellulose Derivatives.

    PubMed

    Xie, Tian; Taylor, Lynne S

    2016-03-07

    Amorphous solid dispersions (ASDs) have been extensively exploited as a strategy for improving the dissolution performance of poorly water-soluble drugs. However, factors underpinning the observed dissolution profiles are not clearly understood, and the choice of polymeric carriers is largely empirical. In the current study, the dissolution performance of a high drug loading ASD containing the poorly water-soluble, anti-inflammatory agent, celecoxib, was optimized by using binary polymers combinations. Polyacrylic acid (PAA), a highly water-soluble polymer, was used to substantially increase the dissolution rate of the drug, while hydroxypropyl methyl cellulose (HPMC) or HPMC acetate succinate (HPMCAS) were added to stabilize the solid amorphous matrix against crystallization upon hydration, as well as to maintain supersaturation. Quantitative measurements of the impact of the polymers on the solution nucleation and growth rates of celecoxib revealed that, while the cellulose derivatives are effective nucleation inhibitors, it is more difficult to completely prevent crystal growth in solutions containing seed crystals, in particular at high supersaturations. Therefore, it is critical to prevent the formation of crystals in the dissolving matrix during dissolution. By using certain ratios of HPMC and PAA, both rapid release as well as crystallization inhibition could be achieved, even at high drug loadings. Utilizing combinations of polymers may therefore be useful to tailor release profiles while providing optimized crystallization inhibition.

  12. Photochemical process in dichromated photosensitive material: dichromated (polyvinyl alcohol-polyacrylic acid)-- a model for dichromated gelatin?

    NASA Astrophysics Data System (ADS)

    Bolte, Michel; Lessard, Roger A.; Pizzocaro, Christine

    2003-02-01

    Gelatin (G) can be described as a peptidic chain with different pendent groups among which, hydroxy groups-OH, carboxylic groups-COOH and amino groups -NH2. Works performed on polyacrylic acid (PAA), a poymeric chain with only pendent-COOH group and on polyvinyl alcohol (PVA) with only -OH group revelaed the strong influence of the nature of the chemical structure on the photochemical behavior of dichromated photopolymers, DCG, DCPAA and DCPVA. Actually, the stability and the state of complexation of the different chromium species was completely opposite in the two matrices: the stabilization of chromium (V) resulting from the photochemical charge transfer in DCPVA, by complexation with PVA is in contrast to what was observed in DCPAA where chromium (V) was highly instable. Regarding chromium (III), the final reduction chromium species, it is complexed in PAA and not in PVA. The primary proces is identical in DCG and in DCPVA, so PVA appears as a good model of the first step of gelatin behavior. But the material obtained after irradiation and treatment of DCG only contains chromium strongly complexed by gelatin. The experiments performed on films of DC with only a few percents of PAA gave evidence for the strong influence of the presence of the carboxylic groups on the photochemical behavior: the rate of the formation and the stability of chromium species, mainly chromium (V), involved in the process. Chromium (V) appears to play a key role in the photosensitive properties of dichromated materials. The diffraction efficiencies of holograms recorded in DCPAA or DCPVA resemble the profiles of chromium (V) evolution.

  13. Acute toxicity of peracetic acid (PAA) formulations to Ichthyophthirius multifiliis theronts

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) is an antimicrobial disinfectant used in agriculture, food processing and medical facilities. It has recently been suggested as a means to control infestations of Ichthyophthirius multifiliis. The purpose of this study was to determine the acute toxicity of two products contai...

  14. Microwave-assisted synthesis of biocompatible europium-doped calcium hydroxyapatite and fluoroapatite luminescent nanospindles functionalized with poly(acrylic acid).

    PubMed

    Escudero, Alberto; Calvo, Mauricio E; Rivera-Fernández, Sara; de la Fuente, Jesús M; Ocaña, Manuel

    2013-02-12

    Europium-doped calcium hydroxyapatite and fluoroapatite nanophosphors functionalized with poly(acrylic acid) (PAA) have been synthesized through a one-pot microwave-assisted hydrothermal method from aqueous basic solutions containing calcium nitrate, sodium phosphate monobasic, and PAA, as well as sodium fluoride in the case of the fluoroapatite particles. In both cases a spindlelike morphology was obtained, resulting from an aggregation process of smaller subunits which also gave rise to high specific surface area. The size of the nanospindles was 191 (32) × 40 (5) nm for calcium hydroxyapatite and 152 (24) × 38 (6) nm for calcium fluoroapatite. The luminescent nanoparticles showed the typical red luminescence of Eu(3+), which was more efficient for the fluoroapatite particles than for the hydroxyapatite. This is attributed to the presence of OH(-) quenchers in the latter. The nanophosphors showed negligible toxicity for Vero cells. Both PAA-functionalized nanophosphors showed a very high (up to at least 1 week) colloidal stability in 2-(N-morpholino)ethanesulfonic acid (MES) at pH 6.5, which is a commonly used buffer for physiological pH. All these features make both kinds of apatite-based nanoparticles promising tools for biomedical applications, such as luminescent biolabels and tracking devices in drug delivery systems.

  15. Mechanical properties of a waterborne pressure-sensitive adhesive with a percolating poly(acrylic acid)-based diblock copolymer network: effect of pH.

    PubMed

    Gurney, Robert S; Morse, Andrew; Siband, Elodie; Dupin, Damien; Armes, Steven P; Keddie, Joseph L

    2015-06-15

    Copolymerizing an acrylic acid comonomer is often beneficial for the adhesive properties of waterborne pressure-sensitive adhesives (PSAs). Here, we demonstrate a new strategy in which poly(acrylic acid) (PAA) is distributed as a percolating network within a PSA film formed from a polymer colloid. A diblock copolymer composed of PAA and poly(n-butyl acrylate) (PBA) blocks was synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization and adsorbed onto soft acrylic latex particles prior to their film formation. The thin adsorbed shells on the particles create a percolating network that raises the elastic modulus, creep resistance and tensile strength of the final film. When the film formation occurs at pH 10, ionomeric crosslinking occurs, and high tack adhesion is obtained in combination with high creep resistance. The results show that the addition of an amphiphilic PAA-b-PBA diblock copolymer (2.0 wt.%) to a soft latex provides a simple yet effective means of adjusting the mechanical and adhesive properties of the resulting composite film. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Synthesis of lithium iron phosphate/carbon microspheres by using polyacrylic acid coated iron phosphate nanoparticles derived from iron(III) acrylate.

    PubMed

    Xu, Dongwei; He, Yan-Bing; Chu, Xiaodong; Ding, Zhaojun; Li, Baohua; He, Jianfu; Du, Hongda; Qin, Xianying; Kang, Feiyu

    2015-03-01

    Lithium iron phosphate/carbon (LiFePO4 /C) microspheres with high rate and cycling performance are synthesized from iron phosphate/polyacrylic acid (FePO4 /PAA) nanoparticles. Iron(III) acrylate is used as a precursor for both the iron and carbon sources. FePO4 nanoparticles are first produced by a coprecipitation reaction. The byproduct, acrylic acid ions, is polymerized in situ to form a uniform PAA layer on the surface of the FePO4 nanoparticles. The as-prepared LiFePO4 /C microspheres are composed of primary nanoparticles with sizes of 40-50 nm. The nanoparticles are fully coated with a thin, uniform carbon layer derived from the decomposition of the PAA layer. The uniform carbon-coating layer cooperates with interstitial and boundary carbon derived from sucrose successfully to construct an excellent interconnecting conductive network in the microspheres. As a result of the unique structure, the as-prepared LiFePO4 /C microspheres display both high electronic and ionic conductivities, which contribute to their high rate performance (162.9 mAh g(-1) at 0.1C and 126.1 mAh g(-1) at 5C) and excellent cycling stability (97.1% of capacity retention after 500 cycles at 5C/5C).

  17. Separation through crystallization and hydrotropy:. the 6-aminopenicillanic acid (6-APA) and phenoxyacetic acid (PAA) system

    NASA Astrophysics Data System (ADS)

    Tavare, Narayan S.; Jadhav, Vivek K.

    1999-03-01

    The specificity of hydrotropes in solubilization has been successfully employed for the separation of close-boiling isomeric components from their binary mixtures forming simple eutectics, in some cases even at the eutectic compositions. The purpose of this paper is to propose a novel technique of crystallizing 6-aminopenicillanic acid (6-APA) in a good quality and pure crystalline form from product reaction mixture in a hydrotrope environment. The remaining mother liquor may be used to recover crystalline phenoxyacetic acid (PAA) by dilution with water and subsequently to concentrate hydrotrope solution for recycle. Semibatch crystallization experiments for 6-APA in a 2 l laboratory-scale agitated crystallizer with controlled acid addition from product reaction mixture in hydrotrope solution yield better quality crystalline product than that in absence of hydrotrope. The present study demonstrates the potential efficacy of sodium butyl monoglycol sulphate (NaBMGS) hydrotrope in the separation of 6-APA in pure crystalline form from the product reaction mixture.

  18. Toward "stable-on-the-table" enzymes: improving key properties of catalase by covalent conjugation with poly(acrylic acid).

    PubMed

    Riccardi, Caterina M; Cole, Kyle S; Benson, Kyle R; Ward, Jessamyn R; Bassett, Kayla M; Zhang, Yiren; Zore, Omkar V; Stromer, Bobbi; Kasi, Rajeswari M; Kumar, Challa V

    2014-08-20

    Several key properties of catalase such as thermal stability, resistance to protease degradation, and resistance to ascorbate inhibition were improved, while retaining its structure and activity, by conjugation to poly(acrylic acid) (PAA, Mw 8000) via carbodiimide chemistry where the amine groups on the protein are appended to the carboxyl groups of the polymer. Catalase conjugation was examined at three different pH values (pH 5.0, 6.0, and 7.0) and at three distinct mole ratios (1:100, 1:500, and 1:1000) of catalase to PAA at each reaction pH. The corresponding products are labeled as Cat-PAA(x)-y, where x is the protein to polymer mole ratio and y is the pH used for the synthesis. The coupling reaction consumed about 60-70% of the primary amines on the catalase; all samples were completely water-soluble and formed nanogels, as evidenced by gel electrophoresis and electron microscopy. The UV circular dichroism (CD) spectra indicated substantial retention of protein secondary structure for all samples, which increased to 100% with increasing pH of the synthesis and polymer mole fraction. Soret CD bands of all samples indicated loss of ∼50% of band intensities, independent of the reaction pH. Catalytic activities of the conjugates increased with increasing synthesis pH, where 55-80% and 90-100% activity was retained for all samples synthesized at pH 5.0 and pH 7.0, respectively, and the Km or Vmax values of Cat-PAA(100)-7 did not differ significantly from those of the free enzyme. All conjugates synthesized at pH 7.0 were thermally stable even when heated to ∼85-90 °C, while native catalase denatured between 55 and 65 °C. All conjugates retained 40-90% of their original activities even after storing for 10 weeks at 8 °C, while unmodified catalase lost all of its activity within 2 weeks, under similar storage conditions. Interestingly, PAA surrounding catalase limited access to the enzyme from large molecules like proteases and significantly increased

  19. Radiation induced deposition of copper nanoparticles inside the nanochannels of poly(acrylic acid)-grafted poly(ethylene terephthalate) track-etched membranes

    NASA Astrophysics Data System (ADS)

    Korolkov, Ilya V.; Güven, Olgun; Mashentseva, Anastassiya A.; Atıcı, Ayse Bakar; Gorin, Yevgeniy G.; Zdorovets, Maxim V.; Taltenov, Abzal A.

    2017-01-01

    Poly(ethylene terephthalate) PET, track-etched membranes (TeMs) with 400 nm average pore size were UV-grafted with poly(acrylic acid) (PAA) after oxidation of inner surfaces by H2O2/UV system. Carboxylate groups of grafted PAA chains were easily complexed with Cu2+ ions in aqueous solutions. These ions were converted into metallic copper nanoparticles (NPs) by radiation-induced reduction of copper ions in aqueous-alcohol solution by gamma rays in the dose range of 46-250 kGy. Copper ions chelating with -COOH groups of PAA chains grafted on PET TeMs form polymer-metal ion complex that prevent the formation of agglomerates during reduction of copper ions to metallic nanoparticles. The detailed analysis by X-Ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the deposition of copper nanoparticles with the average size of 70 nm on the inner surface of nanochannels of PET TeMs. Samples were also investigated by FTIR, ESR spectroscopies to follow copper ion reduction.

  20. Ingenious route for ultraviolet-induced graft polymerization achieved on inorganic particle: Fabricating magnetic poly(acrylic acid) densely grafted nanocomposites for Cu2+ removal

    NASA Astrophysics Data System (ADS)

    Zhou, Qi; Luo, Wenjun; Zhang, Xing

    2017-08-01

    In this study, ultraviolet (UV)-induced graft technology is improved to be successfully applied on inorganic substrate for fabricating a novel poly(acrylic acid) (PAA) brushes-decorated magnetic nano-composite particles (g-MNPs) as a potential adsorbent toward Cu2+ ion. The most fascinating features of the resultant g-MNPs are the abundant and highly accessible carboxyl groups present in PAA brushes and the rapid separation from the medium by magnetic field after adsorption. Through the new and high-efficiency surface-initiated polymerization route, the densely PAA brushes was successfully immobilized on the MNPs surface with a high grafting yield of 88.3%. Excitingly, the g-MNPs exhibited an exceptional performance for Cu2+ adsorption, e.g., ultrahigh adsorption capacity (up to 152.1 mg g-1), rapid adsorption rate (within 30 min) and low residual concentration (below 1.3 ppm). Full kinetic and isotherm analysis as well as thermodynamic study were also undertaken, the results showed that Cu2+ adsorption followed Langmuir isotherm and the pseudo-second-order kinetic model, the adsorption rate was controlled by two sequential periods of external and intraparticle diffusion. According to the calculated value of thermodynamic parameters, the Cu2+ adsorption onto g-MNPs was a spontaneous endothermic process. Furthermore, the excellent reusability of the resultant adsorbent was also confirmed, which can keep above 95% adsorption capacity and desorption rate in 8 consecutive cycles.

  1. Synthesis and characterization of polyacrylic acid- grafted-carboxylic graphene/titanium nanotube composite for the effective removal of enrofloxacin from aqueous solutions: Adsorption and photocatalytic degradation studies.

    PubMed

    Anirudhan, Thayyath S; Shainy, F; Christa, J

    2017-02-15

    Polyacrylic acid-grafted-carboxylic graphene/titanium nanotube (PAA-g-CGR/TNT) composite was synthesized. It was effectively used as adsorbent as well as photocatalyst. The composite was characterized by FTIR, XRD, SEM, TEM, Surface Area Analyzer, XPS and DRS. The photocatalytic activity of PAA-g-CGR/TNT composite was evaluated on the basis of the degradation of pollutants by using sunlight. The band gap of the prepared photocatalyst was found to be 2.6eV. The removal of the antibiotic enrofloxacin (ENR) was achieved by two step mechanism based on adsorption and photodegradation. The maximum adsorption was observed at pH 5.0. The best fitted kinetic model was found to be pseudo-second-order. The maximum adsorption was observed at 30°C. The maximum adsorption capacity was found to be 13.40mg/g. The kinetics of photodegradation of ENR onto PAA-g-CGR/TNT composite follow first-order kinetics and optimum pH was found to be 5.0. The regeneration and reuse of the adsorbent-cum-photocatalyst were also examined upto five cycles.

  2. pH-responsive drug delivery system based on luminescent CaF(2):Ce(3+)/Tb(3+)-poly(acrylic acid) hybrid microspheres.

    PubMed

    Dai, Yunlu; Zhang, Cuimiao; Cheng, Ziyong; Ma, Ping'an; Li, Chunxia; Kang, Xiaojiao; Yang, Dongmei; Lin, Jun

    2012-03-01

    In this study, we design a controlled release system based on CaF(2):Ce(3+)/Tb(3+)-poly(acrylic acid) (PAA) composite microspheres, which were fabricated by filling the pH-responsive PAA inside CaF(2):Ce(3+)/Tb(3+) hollow spheres via photopolymerization route. The CaF(2):Ce(3+)/Tb(3+) hollow spheres prepared by hydrothermal route possess mesoporous structure and show strong green fluorescence from Tb(3+) under UV excitation. Doxorubicin hydrochloride (DOX), a widely used anti-cancer drug, was used as a model drug to evaluate the loading and controlled release behaviors of the composite microspheres due to the good biocompatibility of the samples using MTT assay. The composite carriers provide a strongly pH-dependent drug release behavior owing to the intrinsic property of PAA and its interactions with DOX. The endocytosis process of drug-loaded microspheres was observed using confocal laser scanning microscopy (CLSM) and the in vitro cytotoxic effect against SKOV3 ovarian cancer cells of the DOX-loaded carriers was investigated. In addition, the extent of drug release could be monitored by the altering of photoluminescence (PL) intensity of CaF(2):Ce(3+)/Tb(3+). Considering the good biocompatibility, high drug loading content and pH-dependent drug release of the materials, these hybrid luminescent microspheres have potential applications in drug controlled release and disease therapy.

  3. Controlled release camptothecin tablets based on pluronic and poly(acrylic acid) copolymer. Effect of fabrication technique on drug stability, tablet structure, and release mode.

    PubMed

    Bromberg, Lev; Hatton, T Alan; Barreiro-Iglesias, Rafael; Alvarez-Lorenzo, Carmen; Concheiro, Angel

    2007-06-01

    Poly(ethylene oxide)-b-poly(propylene oxide)-b-(polyethylene oxide)-g-poly(acrylic acid), a graft-comb copolymer of Pluronic 127 and poly(acrylic acid) (Pluronic-PAA), was explored as an excipient for tablet dosage form of camptothecin (CPT). The tablets were prepared by either direct compression of the drug-polymer physical blend, suspension in ethanol followed by evaporation, or compression after kneading and characterized with respect to their physical structures, drug stability, and release behavior. Porosity and water uptake rate were strongly dependent on the fabrication procedure, ranking in the order: direct compression of physical blend > compression after suspension/evaporation in ethanol > compression after kneading. Tablets prepared by compression of physical blends swelled in water with a rapid surface gel layer formation that impeded swelling and disintegration of the tablets core. These tablets were able to sustain the CPT release for a period of time longer than those observed with the tablets made by either suspension/evaporation or kneading, which disintegrated within a few minutes. Despite the tablet disintegration, the CPT release was impeded for at least 6 hr, which was attributed to the ability of the Pluronic-PAA copolymers to form micellar aggregates at the hydrated surface of the particles. Physical mixing did not alter the fraction of CPT being in the pharmaceutically active lactone form, whilst the preparation of the tablets by the other two methods caused a significant reduction in the lactone form content. Tablets prepared from the physical blends demonstrated CPT release rates increasing with the pH due to the PAA ionization leading to the increase in the rate and extent of the tablet swelling. The results obtained demonstrate the potential of the Pluronic-PAA copolymers for the oral administration of chemotherapeutic agents.

  4. PAA/PEO comb polymer effects on the rheological property evolution in concentrated cement suspensions

    NASA Astrophysics Data System (ADS)

    Kirby, Glen Harold

    We have studied the behavior of polyelectrolyte-based comb polymers in dilute solution and on the rheological property evolution of concentrated Portland cement suspensions. These species consisted of charge-neutral, poly(ethylene oxide) (PEO) "teeth" grafted onto a poly(acrylic acid) (PAA) "backbone" that contains one ionizable carboxylic acid group (COOH) per monomer unit. As a benchmark, our observations were compared to those obtained for pure cement pastes and systems containing pure polyelectrolyte species, i.e., sulfonated naphthalene formaldehyde (SNF) and poly(acrylic acid) (PAA). The behavior of PAA/PEO comb polymers, SNF, and PAA in dilute solution was studied as a function of pH in the absence and presence of mono-, di-, and trivalent counterions. Light scattering and turbidity measurements were carried out to assess their hydrodynamic radius and stability in aqueous solution, respectively. PAA experienced large conformational changes as a function of solution pH and ionic strength. Moreover, dilute solutions of ionized SNF and PAA species became unstable in the presence of multivalent counterions due to ion-bridging interactions. PAA/PEO solutions exhibited enhanced stability relative to pure polyelectrolytes under analogous conditions. The charge neutral PEO teeth shielded the underlying PAA backbone from ion-bridging interactions. In addition, such species hindered conformational changes in solution due to steric interactions between adjacent teeth. A new oscillatory shear technique was developed to probe the rheological property evolution of concentrated cement systems. The rheological property evolution of ordinary and white Portland cement systems were studied in the absence and presence of pure polyelectrolytes and PAA/PEO comb polymers with a wide range of PAA backbone molecular weight, PEO teeth molecular weight, and acid:imide ratio. Cement-PAA suspensions experienced rapid irreversible stiffening and set at 6 min due to ion

  5. Intensification of depolymerization of polyacrylic acid solution using different approaches based on ultrasound and solar irradiation with intensification studies.

    PubMed

    Prajapat, Amrutlal L; Gogate, Parag R

    2016-09-01

    Depolymerization of polyacrylic acid (PAA) as sodium salt has been investigated using ultrasonic and solar irradiations with process intensification studies based on combination with hydrogen peroxide (H2O2) and ozone (O3). Effect of solar intensity, ozone flow and ultrasonic power dissipation on the extent of viscosity reduction has been investigated for individual treatment approaches. The combined approaches such as US+solar, solar+O3, solar+H2O2, US+H2O2 and US+O3 have been subsequently investigated under optimum conditions and established to be more efficient as compared to individual approaches. Approach based on US (60W)+solar+H2O2 (0.01%) resulted in the maximum extent of viscosity reduction as 98.97% in 35min whereas operation of solar+H2O2 (0.01%), US (60W), H2O2 (0.3%) and solar irradiation resulted in about 98.08%, 90.13%, 8.91% and 90.77% intrinsic viscosity reduction in 60min respectively. Approach of US (60W)+solar+ozone (400mg/h flow rate) resulted in extent of viscosity reduction as 99.47% in 35min whereas only ozone (400mg/h flow rate), ozone (400mg/h flow rate)+US (60W) and ozone (400mg/h flow rate)+solar resulted in 69.04%, 98.97% and 98.51% reduction in 60min, 55min and 55min respectively. The chemical identity of the treated polymer using combined approaches was also characterized using FTIR (Fourier transform infrared) spectra and it was established that no significant structural changes were obtained during the treatment. Overall, it can be said that the combination technique based on US and solar irradiations in the presence of hydrogen peroxide is the best approach for the depolymerization of PAA solution.

  6. 40 CFR 721.10702 - Polyfluorinated alkyl thio polyacrylic acid-acrylamide (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... acid-acrylamide (generic). 721.10702 Section 721.10702 Protection of Environment ENVIRONMENTAL...-acrylamide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as polyfluorinated alkyl thio polyacrylic acid-acrylamide (PMN P-11-534)...

  7. Dielectric relaxations of poly(acrylic acid)-graft-poly(ethylene oxide) aqueous solution: Analysis coupled with scaling approach and hydrogen-bonding complex

    NASA Astrophysics Data System (ADS)

    Li, Jingliang; Zhao, Kongshuang; Liu, Chunyan

    2013-04-01

    Dielectric properties of poly(acrylic acid)-graft-poly(ethylene oxide) (PAA-g-PEO) aqueous solution were measured as a function of concentration and temperature over a frequency range of 40 Hz to 110 MHz. After subtracting the contribution of electrode polarization, three relaxation processes were observed at about 20 kHz, 220 kHz, and 4 MHz, and they are named low-, mid- and high-frequency relaxation, respectively. The relaxation parameters of these three relaxations (dielectric increment Δɛ and relaxation time τ) showed scaling relations with the polyelectrolyte concentration. The mechanisms of the three relaxations were concluded in light of the scaling theory: The relaxations of low- and mid frequency were attributed to the fluctuation of condensed counterions, while the high-frequency relaxation was ascribed to the fluctuation of free counterions. Based on the dielectric measurements of varying temperatures, the thermodynamic parameters (enthalpy change ΔH and entropy change ΔS) of the three relaxations were calculated and these relaxation processes were also discussed from the microscopic thermodynamical view. In addition, the impacts of PEO side chains on the conformation of PAA-g-PEO chains were discussed. PEO side chains greatly strengthen the hydrogen-bonding interactions between PAA-g-PEO chains, resulting in the chains overlapping at a very low concentration and the formation of a hydrogen-bonding complex. Some physicochemical parameters of PAA-g-PEO molecules were calculated, including the overlap concentration, the effective charge of the chain, the friction coefficient, and the diffusion coefficient of hydrogen counterions.

  8. Disinfection with peracetic acid (PAA), an alternative against fish pathogens

    USDA-ARS?s Scientific Manuscript database

    Because of the lack of approved substances to treat fish diseases, disinfecting substances are tested to treat fish pathogens. These agents should not leave dangerous residues in the environment in order to successfully contribute to sustainable aquaculture. One of these substances is peracetic acid...

  9. Formulating gels for decreased mucociliary transport using rheologic properties: polyacrylic acids.

    PubMed

    Shah, Ankur J; Donovan, Maureen D

    2007-04-20

    The purpose of these studies was to identify the rheologic properties of polyacrylic acid gels necessary for optimal reductions in mucociliary clearance. The mucociliary transport of 2 bioadhesive polyacrylic acid polymers, polycarbophil and carbopol, was assessed in vitro by measuring their clearance rates across explants of ciliated bovine tracheal tissue. The viscoelastic properties of polymer gels were measured in the presence of mucus using controlled stress rheometry. Combinations of apparent viscosity (eta) and complex modulus (G*) were found to be the most useful parameters in the identification of polyacrylic acid formulations capable of decreasing mucociliary transport rate (MTR). A narrow range of eta and G* values suitable for reducing mucociliary clearance, while remaining sufficiently fluid for intranasal administration, were identified. The correlations between the rheologic parameters of the polycarbophil gels and their mucociliary transport rates were used to identify other polyacrylic acid gels that also had suitable mucociliary clearance properties, demonstrating that these parameters can be used to direct the optimization of formulations using simple in vitro rheologic testing.

  10. Poly(acrylic acid) to induce competitive crystallization of a theophylline/oxalic acid cocrystal and a theophylline polymorph

    NASA Astrophysics Data System (ADS)

    Jang, Jisun; Kim, Il Won

    2016-01-01

    Polymeric additives to induce competitive crystallization of pharmaceutical compounds were explored. A cocrystal of theophylline and oxalic acid was used as a model system, and poly(acrylic acid), poly(caprolactone), and poly(ethylene glycol) were the additives. The cocrystal formation was selectively hindered with addition of poly(acrylic acid). First the size of the cocrystals were reduced, and eventually the cocrystallization was inhibited to generate neat theophylline crystals. The theophylline crystals were of a distinctively different crystal structure from known polymorphs, based on powder X-ray diffraction. They were also obtained in nanoscale size, when millimeter-scale crystals formed without poly(acrylic acid). Polymeric additives that could form specific interactions with crystallizing compounds seem to be useful tools for the phase and size control of pharmaceutical crystals.

  11. One-bottle self-etching adhesives applied to dentine air-abraded using bioactive glasses containing polyacrylic acid: an in vitro microtensile bond strength and confocal microscopy study.

    PubMed

    Sauro, Salvatore; Watson, Timothy F; Thompson, Ian; Banerjee, Avijit

    2012-11-01

    The aim of this study was to test the microtensile bond strength (μTBS) of two "simplified" self-etching adhesives bonded to air-abraded dentine using experimental bioactive glass powders containing polyacrylic acid. Sound dentine specimens were air-abraded using a pure Bioglass 45S5 (Bioglass) powder or two Bioglass powders containing different concentration of polyacrylic acid (PAA: 15 wt% or 40 wt%). The bonding procedures were accomplished by the application of two self-etching adhesives (CS3: Clearfil S3 Bond; Kuraray, Osaka, Japan or GB: G Bond; GC Ltd. Tokyo, Japan). The resin-bonded specimens were cut in beams (0.9 mm(2)) and the μTBS testing was performed after 24h or 6months of phosphate buffer solution (PBS) storage. The results were statistically analysed by three-way ANOVA and Student-Newman-Keuls test used (α=0.05). Further bonded-dentine specimens were used for the confocal microscopy interfacial characterisation and micropermeability analysis. The CS3 adhesive system achieved higher μTBS than those attained in the specimens bonded with GB both after 24h and 6 months of PBS storage. The CLSM analysis performed after 6months of PBS storage indicated severe micropermeability within the bonded-dentine interfaces created using GB applied onto dentine air-abraded with Bioglass/PAA-15 and Bioglass/PAA-40. Conversely, CS3 exhibited no dye penetration (micropermeability) at the resin-dentine interface. It is possible to affirm that air-abrasion procedures performed using pure Bioglass or Bioglass containing 15 wt% PAA do not interfere with the immediate bonding performance of self-etching adhesives. However, the durability of the bonded-dentine interfaces created subsequent air-abrasion procedures using bioactive glasses will depend also upon the chemical composition of the self-etch adhesive systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. In vitro development and evaluation of a polyacrylic acid-silicone device intended for gradual occlusion of portosystemic shunts in dogs and cats.

    PubMed

    Wallace, Mandy L; Ellison, Gary W; Batich, Christopher; Case, J Brad; Kim, Stanley E

    2016-03-01

    To develop a device intended for gradual venous occlusion over 4 to 6 weeks. Silicone tubing filled with various inorganic salt and polyacrylic acid (PAA) formulations and mounted within a polypropylene or polyether ether ketone (PEEK) outer ring. 15 polypropylene prototype rings were initially filled with 1 of 5 formulations and placed in PBSS. In a second test, 10 polypropylene and 7 PEEK prototype rings were filled with 1 formulation and placed in PBSS. In a third test, 2 formulations were loaded into 6 PEEK rings each, placed in physiologic solution, and incubated. In all tests, ring luminal diameter, outer diameter, and luminal area were measured over 6 weeks. In the first test, 2 formulations had the greatest changes in luminal area and diameter, and 1 of those had a greater linear swell rate than the other had. In the second test, 6 of 7 PEEK rings and 6 of 10 polypropylene rings closed to a luminal diamater < 1 mm within 6 weeks. Polypropylene rings had a greater increase in outer diameter than did PEEK rings between 4.5 and 6 weeks. In the third test, 11 of 12 PEEK rings gradually closed to a luminal diameter < 1 mm within 6 weeks. A PAA and inorganic salt formulation in a prototype silicone and polymer ring resulted in gradual occlusion over 4 to 6 weeks in vitro. Prototype PEEK rings provided more reliable closure than did polypropylene rings.

  13. One-step formation of lipid-polyacrylic acid-calcium carbonate nanoparticles for co-delivery of doxorubicin and curcumin.

    PubMed

    Peng, Jianqing; Fumoto, Shintaro; Miyamoto, Hirotaka; Chen, Yi; Kuroda, Naotaka; Nishida, Koyo

    2017-09-01

    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. This 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 (EE) and pH-sensitive drug release using a simplified preparation method. Optimisation of lipid ratios and concentrations of CaCO3 was conducted. Under optimal conditions, the mean diameter of PEGylated lipid/PAA/CaCO3 nanoparticles with encapsulated Cur and Dox (LPCCD) was less than 100 nm. An obvious pH-sensitive release of both drugs was observed, with different Dox and Cur release rates. Successful co-delivery of Cur and Dox was achieved via LPCCD on HepG2 cells. LPCCD altered the bio-distribution of Dox and Cur in vivo and decreased Dox-induced cardiotoxicity. The current investigation has developed an efficient ternary system for co-delivery of Dox and Cur to tumours, using a "one-step" formation resulting in nanoparticles possessing remarkable pH-sensitive drug release behaviour, which may be valuable for further clinical studies and eventual clinical application.

  14. Disk morphology and disk-to-cylinder tunability of poly(acrylic acid)-b-poly(methyl acrylate)-b-polystyrene triblock copolymer solution-state assemblies.

    PubMed

    Li, Zhibin; Chen, Zhiyun; Cui, Honggang; Hales, Kelly; Qi, Kai; Wooley, Karen L; Pochan, Darrin J

    2005-08-02

    Disk and cylindrical micellar assemblies were formed through self-organization of poly(acrylic acid)-b-poly(methyl acrylate)-b-polystyrene (PAA-b-PMA-b-PS) amphiphilic triblock copolymers with organic diamines as counterions in water/ tetrahydrofuran (THF) solvent mixtures. The system was investigated by means of transmission electron microscopy and cryogenic transmission electron microscopy. It was found that the assembled-state morphologies could be modified by alteration of the type and concentration of cationic diamine counterion undergoing interaction with the negatively charged, polyelectrolyte PAA corona block, the relative amount of water in the water/THF mixture, and the hydrophobic block chain length. Multivalency of the organic amine counterion was critical for disk formation. It was further demonstrated that a single block copolymer underwent disc-to-cylindrical micellar transitions reversibly with variation in the relative water/THF ratio. The ability to form disks beginning from either THF-rich or water-rich solutions indicated that the disk morphology was thermodynamically stable and that THF was important in keeping the micellar structure from becoming kinetically frozen. The nanoassemblies were produced having low size dispersities and were stable for at least one month. Intermediate structures between disks and cylinders were also observed, indicating two distinct kinetic pathways between the two micelle structures.

  15. Enhanced stability of polyacrylate-coated magnetite nanoparticles in biorelevant media.

    PubMed

    Hajdú, Angéla; Szekeres, Márta; Tóth, Ildikó Y; Bauer, Rita A; Mihály, Judith; Zupkó, István; Tombácz, Etelka

    2012-06-01

    Magnetite nanoparticles (MNPs) were prepared by alkaline hydrolysis of Fe(II) and Fe(III) chlorides. Adsorption of polyacrylic acid (PAA) on MNPs was measured at pH=6.5±0.3 and I=0.01 M (NaCl) to find the optimal PAA amount for MNP stabilization under physiological conditions. We detected an H-bond formation between magnetite surface groups and PAA by ATR-FTIR measurements, but bonds of metal ion-carboxylate complexes, generally cited in literature, were not identified at the given pH and ionic strength. The dependence of the electrokinetic potential and the aggregation state on the amount of added PAA at various pHs was measured by electrophoretic mobility and dynamic light-scattering methods. The electrokinetic potential of the naked MNPs was low at near physiological pH, but PAA adsorption overcharged the particles. Highly negatively charged, well-stabilized carboxylated MNPs formed via adsorption of PAA in an amount of approximately ten times of that necessary to compensate the original positive charge of the magnetite. Coagulation kinetics experiments revealed gradual enhancement of salt tolerance at physiological pH from ~0.001 M at no added PAA up to ~0.5 M at 1.12 mmol/g PAA. The PAA-coated MNPs exert no substantial effect on the proliferation of malignant (HeLa) or non-cancerous fibroblast cells (MRC-5) as determined by means of MTT assays.

  16. Microchip electrophoresis with background electrolyte containing polyacrylic acid and high content organic solvent in cyclic olefin copolymer microchips for easily adsorbed dyes.

    PubMed

    Wei, Xuan; Sun, Ping; Yang, Shenghong; Zhao, Lei; Wu, Jing; Li, Fengyun; Pu, Qiaosheng

    2016-07-29

    Plastic microchips can significantly reduce the fabrication cost but the adsorption of some analytes limits their application. In this work, background electrolyte containing ionic polymer and high content of organic solvent was adopted to eliminate the analyte adsorption and achieve highly efficient separation in microchip electrophoresis. Two dyes, rhodamine 6G (Rh6G) and rhodamine B (RhB) were used as the model analytes. By using methanol as the organic solvent and polyacrylic acid (PAA) as a multifunctional additive, successful separation of the two dyes within 75μm id. microchannels was realized. The role of PAA is multiple, including viscosity regulator, selectivity modifier and active additive for counteracting analyte adsorption on the microchannel surface. The number of theoretical plate of 7.0×10(5)/m was attained within an effective separation distance of 2cm using background electrolyte consisting 80% methanol, 0.36% PAA and 30mmol/L phosphate at pH 5.0. Under optimized conditions, relative standard deviations of Rh6G and RhB detection (n=5) were no more than 1.5% for migration time and 2.0% for peak area, respectively. The limit of detection (S/N=3) was 0.1nmol/L for Rh6G. The proposed technique was applied in the determination of both Rh6G and RhB in chilli powder and lipstick samples with satisfactory recoveries of 81.3-103.7%. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Dispersion of alumina-coated TiO2 slurries in the presence of poly(acrylic) acid influence of monovalent counterions.

    PubMed

    Boisvert, Jean-Philippe; Malgat, Alexandre

    2005-01-15

    The rheological behavior of concentrated alumina-coated TiO2 slurries has been investigated in connection with the type of surface counterions (monovalent cations: X = Li+, Na+, TMA+) in the absence and in the presence of polyacrylic acid (PAA). The study has been conducted in a pH range of 4-10 and with ionic strengths lower than 0.01 M. The pH and ionic strength were adjusted with XOH and XCl, respectively. The surface properties have been investigated by titration of surface counterions and the apparent yield stress has been measured using a dynamic stress rheometer. It appears from the results that the pH at the maximum yield stress and the magnitude of the yield stress depend on the nature of the counterion. The yield stress measurements were also conducted in the presence of PAA (0.5 segment/nm2) adsorbed on the particle surface. In that case, the mineral surface and adsorbed polymer were neutralized with XOH. The results show that the dispersion efficiency depends on the polymer counterion. In general, it is found that the maximum yield stress and the corresponding counterion surface density both follow the sequence TMA+ < Na+ < Li+. The adsorption of PAA apparently amplifies the effects observed with the corresponding cation. An electrostriction effect of the hydration layer at the interface is suggested in order to explain the increasing yield stress as the surface density of Li+ increases. The so-called structure-making/structure-breaking model explains the yield stress reduction with the TMA+ surface density.

  18. Improved In Vitro and In Vivo Biocompatibility of Graphene Oxide through Surface Modification: Poly(Acrylic Acid)-Functionalization is Superior to PEGylation.

    PubMed

    Xu, Ming; Zhu, Jianqiang; Wang, Fanfan; Xiong, Yunjing; Wu, Yakun; Wang, Qiuquan; Weng, Jian; Zhang, Zhihong; Chen, Wei; Liu, Sijin

    2016-03-22

    The unique physicochemical properties of two-dimensional (2D) graphene oxide (GO) could greatly benefit the biomedical field; however, recent research demonstrated that GO could induce in vitro and in vivo toxicity. We determined the mechanism of GO induced toxicity, and our in vitro experiments revealed that pristine GO could impair cell membrane integrity and functions including regulation of membrane- and cytoskeleton-associated genes, membrane permeability, fluidity and ion channels. Furthermore, GO induced platelet depletion, pro-inflammatory response and pathological changes of lung and liver in mice. To improve the biocompatibility of pristine GO, we prepared a series of GO derivatives including aminated GO (GO-NH2), poly(acrylamide)-functionalized GO (GO-PAM), poly(acrylic acid)-functionalized GO (GO-PAA) and poly(ethylene glycol)-functionalized GO (GO-PEG), and compared their toxicity with pristine GO in vitro and in vivo. Among these GO derivatives, GO-PEG and GO-PAA induced less toxicity than pristine GO, and GO-PAA was the most biocompatible one in vitro and in vivo. The differences in biocompatibility were due to the differential compositions of protein corona, especially immunoglobulin G (IgG), formed on their surfaces that determine their cell membrane interaction and cellular uptake, the extent of platelet depletion in blood, thrombus formation under short-term exposure and the pro-inflammatory effects under long-term exposure. Overall, our combined data delineated the key molecular mechanisms underlying the in vivo and in vitro biological behaviors and toxicity of pristine GO, and identified a safer GO derivative that could be used for future applications.

  19. High strength of physical hydrogels based on poly(acrylic acid)-g-poly(ethylene glycol) methyl ether: role of chain architecture on hydrogel properties.

    PubMed

    Yang, Jun; Gong, Cheng; Shi, Fu-Kuan; Xie, Xu-Ming

    2012-10-04

    This investigation was to study the connections between polymer branch architecture of physical hydrogels and their properties. The bottle-brush-like polymer chains of poly(acrylic acid)-g-poly(ethylene glycol) methyl ether (PAA-g-mPEG) with PAA as backbones and mPEG as branch architecture were synthesized and in situ grafted from silica nanoparticles (SNs) to construct hydrogels cross-linked networks in aqueous solutions. The structural variables to be discussed included molecular weight and molar ratio of branch chains, and new aspects of the formation mechanism of physical hydrogels with branch structure in the absence of organic cross-links were present. The results indicated that the differences of polymer chain architecture could be distinguished via their different interactions that are present by gelation process and mature gel properties, such as gel strength and swelling ratio. The gelation occurred at the critical polymer concentration and molecular weight, respectively, and the inorganic/organic (SNs/PAA-g-mPEG) nanoparticles began to entangle and construct the cross-linking networks afterward. The gel-to-sol transition temperature (T(g-s)) and radii of SNs that were encapsulated by polymer chains as a function of time for chains' disentanglement were monitored according to the observation of the dissolution process, and the molecular weight between two consecutive entanglements (M(e)) was calculated thereafter. This study showed that the introduction of branch chain onto the linear backbone significantly promoted the chain interactions and increased entanglement density, which contributed to the hydrogels' network integrity and rigidity, thus illustrating greater elongation at break and tensile strength than the hydrogels formulated with linear polymer chains.

  20. Spectroscopy of a Gamma Irradiated Poly(Acrylic Acid)-Clotrimazole System

    NASA Astrophysics Data System (ADS)

    Todica, M.; V. Pop, C.; Luciana, Udrescu; Traian, Stefan

    2011-12-01

    A poly(acrylic acid)-clotrimazole system, gamma irradiated at different doses, is investigated by Raman spectroscopy. Modifications of the spectrum of the polymeric matrix appear for doses of radiation greater than 333 Gy, whereas the spectrum of clotrimazole remains unaffected at these doses of radiation. These changes correlate with modification of the vibration modes of COOH and CH2 groups of a polymeric matrix after irradiation.

  1. Can polyacrylic acid treat sexual dysfunction in women with breast cancer receiving tamoxifen?

    PubMed

    Juliato, P T; Rodrigues, A T; Stahlschmidt, R; Juliato, C R T; Mazzola, P G

    2017-02-01

    There is a lack of safety data supporting the use of hormone therapy in women who have had breast cancer and who have complained of genitourinary syndrome of menopause (GSM). The objective was to test the efficacy of two non-hormonal therapies for vaginal dryness. This was a randomized trial with 52 women with breast cancer who were being treated with tamoxifen and who complained of vaginal dryness. The volunteers answered two questionnaires to evaluate sexual function (Female Sexual Function Index, FSFI) and a customized GSM questionnaire. The women were randomized into two groups: 25 (48.1%) in the polyacrylic acid group and 27 (51.9%) in the lubricant group, using either one of the treatments for 30 days, and after they were invited to answer the questionnaires again. There was improvement in the FSFI after both treatments. The polyacrylic acid group showed a decrease in sexual dysfunction from 96% to 24% (p < 0.0001) and the lubricant group showed a decrease from 88.9% to 55.6% (p = 0.0027). The results of this study showed that both treatments improved sexual function; however, polyacrylic acid was superior to the lubricant in treating sexual dysfunction.

  2. [Antiparasitic effects of peracetic acid (PAA) against infective stages (theronts) of white spot disease, Ichthyophthirius multifiliis in vitro].

    PubMed

    Meinelt, T; Staaks, J; Staaks, G; Stüber, A; Bräunig, I

    2007-10-01

    White spot disease, caused by the protozoan parasite Ichthyophthirius multifiliis (I. multifiliis), invades nearly all fresh water fish species and causes huge economic losses. In Germany no protocide substance is legal for the treatment of I. multifilis. As an alternative substance the peracetic acid (PAA) was tested to treat the free invasive stage (theront) of the parasite. PAA concentrations of 0.3 ppm were able to kill all theronts in 120 min in our investigations. As a result of these investigations we recommend an interval-application of 0.3 to 0.5 ppm PAA for 30 to 150 min. This application should be prolonged for two life cycles of the parasite. Biotic parameters as e. g. fish species, and age as well as abiotic parameters as e. g. temperature, pH and organic load of the water could possibly influence the efficiency of the PAA application and should therefore be taken into account while picking the dosage and length of the PAA exposure.

  3. Cell-targeted, dual reduction- and pH-responsive saccharide/lipoic acid-modified poly(L-lysine) and poly(acrylic acid) polyionic complex nanogels for drug delivery.

    PubMed

    How, Su-Chun; Chen, Yu-Fon; Hsieh, Pin-Lun; Wang, Steven S-S; Jan, Jeng-Shiung

    2017-05-01

    A cell-targeted, reduction-/pH-responsive polyionic complex (PIC) nanogel system was developed by simply mixing cationic lactobionolatone/lipoic acid-modified poly(L-lysine) (PLL-g-(Lipo-Lac)) and anionic poly(acrylic acid) (PAA), followed by disulfide cross-linking. The nanogels with sizes smaller than 150nm can be prepared at certain mixing ratio via forming interchain disulfide cross-link and helical PAA/PLL complexes. In vitro drug release study showed that Doxorubicin (Dox) release from the nanogels was significantly enhanced by increasing acidity and/or introducing disulfide cleaving agent. Carbohydrate-lectin binding and cellular uptake studies confirmed that Lac-conjugated nanogels can effectively bind to the cells bearing asialoglycoprotein receptors and subsequently afford efficient cell internalization. Cytotoxicity assays showed that Dox-loaded, Lac-conjugated nanogels exhibited efficient cell proliferation inhibition toward HepG2 cells, whereas the nanogels exhibited excellent biocompatibility. Furthermore, TUNEL assay was employed to detect apoptosis pertaining to the mechanism of cell death. This study highlights that polyionic complexation with subsequent cross-linking can be a simple approach to prepare multifunctional nanogels as drug delivery vehicles. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Salinity, water hardness, and dissolved organic carbon modulate degradation of peracetic acid (PAA) compounds in aqueous solutions

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) is used in aquaculture under different conditions for disinfection purposes. However, there is a lack of information about its environmental fate, particularly its persistence in aquatic systems with different chemistries. Therefore, the impact of water hardness, salinity, and d...

  5. The transport of phenylacetic acid across the peroxisomal membrane is mediated by the PaaT protein in Penicillium chrysogenum.

    PubMed

    Fernández-Aguado, Marta; Ullán, Ricardo V; Teijeira, Fernando; Rodríguez-Castro, Raquel; Martín, Juan F

    2013-04-01

    Penicillium chrysogenum, an industrial microorganism used worldwide for penicillin production, is an excellent model to study the biochemistry and the cell biology of enzymes involved in the synthesis of secondary metabolites. The well-known peroxisomal location of the last two steps of penicillin biosynthesis (phenylacetyl-CoA ligase and isopenicillin N acyltransferase) requires the import into the peroxisomes of the intermediate isopenicillin N and the precursors phenylacetic acid and coenzyme A. The mechanisms for the molecular transport of these precursors are still poorly understood. In this work, a search was made, in the genome of P. chrysogenum, in order to find a Major Facilitator Superfamily (MFS) membrane protein homologous to CefT of Acremonium chrysogenum, which is known to confer resistance to phenylacetic acid. The paaT gene was found to encode a MFS membrane protein containing 12 transmembrane spanners and one Pex19p-binding domain for Pex19-mediated targeting to peroxisomal membranes. RNA interference-mediated silencing of the paaT gene caused a clear reduction of benzylpenicillin secretion and increased the sensitivity of P. chrysogenum to the penicillin precursor phenylacetic acid. The opposite behavior was found when paaT was overexpressed from the glutamate dehydrogenase promoter that increases phenylacetic acid resistance and penicillin production. Localization studies by fluorescent laser scanning microscopy using PaaT-DsRed and EGFP-SKL fluorescent fusion proteins clearly showed that the protein was located in the peroxisomal membrane. The results suggested that PaaT is involved in penicillin production, most likely through the translocation of side-chain precursors (phenylacetic acid and phenoxyacetic acid) from the cytosol to the peroxisomal lumen across the peroxisomal membrane of P. chrysogenum.

  6. Human mesenchymal stem cell osteoblast differentiation, ECM deposition, and biomineralization on PAH/PAA polyelectrolyte multilayers.

    PubMed

    Pattabhi, Sudhakara Rao; Lehaf, Ali M; Schlenoff, Joseph B; Keller, Thomas C S

    2015-05-01

    Polyelectrolyte multilayer (PEMU) coatings built layer by layer with alternating pairs of polyelectrolytes can be tuned to improve cell interactions with surfaces and may be useful as biocompatible coatings to improve fixation between implants and tissues. Here, we show that human mesenchymal stromal cells (hMSCs) induced with bone differentiation medium (BDM) to become osteoblasts biomineralize crosslinked PEMUs built with the polycation poly(allylamine hydrochloride) (PAH) and the polyanion poly(acrylic acid) (PAA). Degrees of hMSC osteoblast differentiation and surface biomineralization on the smooth PAH-terminated PEMUs (PAH-PEMUs) and microstructured PAA-terminated PEMUs (PAA-PEMUs) reflect differences in cell-deposited extracellular matrix (ECM). BDM-induced hMSCs expressed higher levels of the early osteoblast differentiation marker alkaline phosphatase and collagen 1 (COL1) sooner on PAA-PEMUs than on PAH-PEMUs. Cells on both types of PEMUs proceeded to express the later stage osteoblast differentiation marker bone sialoprotein (BSP), but the BDM-induced cells organized a more amorphous Collagen I and denser BSP localization on PAA-PEMUs than on PAH-PEMUs. These ECM properties correlated with greater biomineralization on the PAA-PEMUs than on PAH-PEMUs. Together, these results confirm the suitability of PAH/PAA PEMUs as a substrate for hMSC osteogenesis and highlight the importance of substrate effects on ECM organization and BSP presentation on biomineralization.

  7. Superabsorbent biphasic system based on poly(lactic acid) and poly(acrylic acid)

    NASA Astrophysics Data System (ADS)

    Sartore, Luciana; Pandini, Stefano; Baldi, Francesco; Bignotti, Fabio

    2016-05-01

    In this research work, biocomposites based on crosslinked particles of poly(acrylic acid), commonly used as superabsorbent polymer (SAP), and poly-L-lactic acid (PLLA) were developed to elucidate the role of the filler (i.e., polymeric crosslinked particles) on the overall physico-mechanical behavior and to obtain superabsorbent thermoplastic products. Samples prepared by melt-blending of components in different ratios showed a biphasic system with a regular distribution of particles, with diameter ranging from 5 to 10 μm, within the PLLA polymeric matrix. The polymeric biphasic system, coded PLASA i.e. superabsorbent poly(lactic acid), showed excellent swelling properties, demonstrating that cross-linked particles retain their superabsorbent ability, as in their free counterparts, even if distributed in a thermoplastic polymeric matrix. The thermal characteristics of the biocomposites evidence enhanced thermal stability in comparison with neat PLLA and also mechanical properties are markedly modified by addition of crosslinked particles which induce regular stiffening effect. Furthermore, in aqueous environments the particles swell and are leached from PLLA matrix generating very high porosity. These new open-pore PLLA foams, produced in absence of organic solvents and chemical foaming agents, with good physico-mechanical properties appear very promising for several applications, for instance in tissue engineering for scaffold production.

  8. Bioinspired bioadhesive polymers: dopa-modified poly(acrylic acid) derivatives.

    PubMed

    Laulicht, Bryan; Mancini, Alexis; Geman, Nathanael; Cho, Daniel; Estrellas, Kenneth; Furtado, Stacia; Hopson, Russell; Tripathi, Anubhav; Mathiowitz, Edith

    2012-11-01

    The one-step synthesis and characterization of novel bioinspired bioadhesive polymers that contain Dopa, implicated in the extremely adhesive byssal fibers of certain gastropods, is reported. The novel polymers consist of combinations of either of two polyanhydride backbones and one of three amino acids, phenylalanine, tyrosine, or Dopa, grafted as side chains. Dopa-grafted hydrophobic backbone polymers exhibit as much as 2.5 × the fracture strength and 2.8 × the tensile work of bioadhesion of a commercially available poly(acrylic acid) derivative as tested on live, excised, rat intestinal tissue. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Adsorption of low cross-linking density hydrogel OMMT/acid hydrolysis lignin grafted polyacrylic acid for Cd (II)

    NASA Astrophysics Data System (ADS)

    Lian, Enxiao; Shi, Ruoli; Deng, Yilin; Zhu, Hongjun; Ma, Yanli

    2017-03-01

    Organic montmorillonite/acid hydrolysis lignin graft poly (acrylic acid) composite superabsorbent (LBPAA/OMMT) was prepared by radical copolymerization of acrylic acid and acid hydrolysis lignin, and OMMT was homogeneous dispersed into hydrogels of LBPAA through supersonic irradiation. Persulphate ammonium was used as an initiator, and N, N'-ethylene bis-acrylamide (MBA) as a crosslinker. Adsorption behavior of water and Cd (II) ion on LBPAA/OMMT were investigated. The biggest capacity of adsorption for Cd (II) is PAA (0.6240 mmol/g). The ΔrH0 values of PAA, LBPAA, and LBPAA/OMMT were found as 116.71, 117.8, 125.15kJ mol-1 for Cd (II), respectively. Negative values of ΔrG0 indicates the spontaneous nature of the reaction.

  10. High strength and low friction of a PAA-alginate-silica hydrogel as potential material for artificial soft tissues.

    PubMed

    Lin, Hong-Ru; Ling, Ming-Hung; Lin, Yiu-Jiuan

    2009-01-01

    In this study, a series of poly(acrylic) acid (PAA)-based hydrogels was prepared by UV polymerization. Hydrogels with an interpenetrating network structure were formed by combining PAA and alginate (Alg) solutions. The incorporation of nano-silica into these gel solutions significantly increased their compressive strength and fracture toughness but lowered their cross-linking density and friction coefficient. The prepared hydrogels were considerably hydrophilic for water content greater than 98%, which is in accordance with the nature of soft tissues such as cartilage. The preliminary cell culture of adipose stem cells (ADSCs) on PAA-Alg-Si hydrogels results in good biological safety. These features suggest that the PAA-Alg-Si hydrogels prepared in this study can be used as artificial soft tissues.

  11. Pervaporation separation of ethanol-water mixtures using polyacrylic acid composite membranes

    DOEpatents

    Neidlinger, H.H.

    1985-05-07

    Synthetic, organic, polymeric membranes were prepared from polyacrylic acid salts for use with pervaporation apparatus in the separation of ehthanol-water mixtures. The polymeric material was prepared in dilute aqueous solution and coated onto a polysulfone support film, from which excess polymeric material was subsequently removed. Cross-links were then generated by limited exposure to toluene-2,4-diisocyanata solution, after which the prepared membrane was heat-cured. The resulting membrane structure showed selectivity in permeating water over a wide range of feed concentrations. 4 tabs.

  12. Poly(acrylic acid-co-methyl methacrylate)/metronidazole systems: synthesis and complexation.

    PubMed

    Bialik-Wąs, Katarzyna; Pielichowski, Krzysztof

    2013-01-01

    We report on preparation of poly(acrylic acid-co-methyl methacrylate) (PAM) micro- and nanoparticles and, in the subsequent stage, complexation reaction with the active substance - metronidazole (MET). The drug release behavior of MET - loaded PAM micro- and nanoparticles was evaluated in water and phosphate buffered saline (PBS, 0.9% NaCl) at 37ºC. It has been found that introduction of MET into PAM micro- and nanoparticles enabled gradual and controlled release of the active substance. Structural analysis using FT-IR (ATR) and (1)H NMR, as well as surface morphology assessment by SEM, were performed.

  13. Interactions between mica surfaces in sodium polyacrylate solutions containing calcium ions

    SciTech Connect

    Berg, J.M.; Claesson, P.M. . Dept of Physical Chemistry); Neuman, R.D. . Dept. of Chemical Engineering)

    1993-11-01

    Polyacrylic acid (PAA) and its salts find use in a number of different applications, such as in fluids for secondary oil recovery, as dispersing agents for mineral suspensions in, for example, ceramic and paper coating applications, and as flocculants for waste-water treatment. The forces acting between negatively charged muscovite mica surfaces immersed in solutions containing sodium polyacrylate (NaPAA) have been studied. No evidence for PAA adsorption in the absence of calcium ions in the solution was found. However, at a CaCl[sub 2] concentration of about 3 [times] 10[sup [minus]3] M a layer of PAA adsorbed on each surface. At large separations, the forces between the PAA-coated surfaces were dominated by repulsive double-layer forces. At separations below 50--80 [angstrom], depending on the solution conditions, an attractive force in excess of the van der Waals attraction was observed. The adhesion force between the layers was 7-8 mN / m at pH 6 and increased somewhat with increasing pH to about 9 mN/m at pH 10. The authors argue that both the long-range attraction and the adhesion force primarily are due to COO[sup [minus

  14. Fabrication and characterization of methylene-blue-doped polyvinyl alcohol-polyacrylic acid blend for holographic recording.

    PubMed

    Ushamani, Mythili; Sreekumar, Krishnapillai; Kartha, Cheranellore S; Joseph, Rani

    2004-06-20

    A methylene-blue-sensitized polymer blend of polyvinyl alcohol and polyacrylic acid is fabricated and tested for holographic recording. It was found to have good characteristics such as high sensitivity, storage stability, ease of fabrication, and environmental stability. Optimization of the ratio of polyvinyl alcohol/polyacrylic acid, the sensitizer concentration, pH, energy, diffraction efficiency measurements, etc., have been done. pH is found to have a great influence on the recovery of the dye in this matrix. The results of experimental investigations into the properties of this new material are reported.

  15. Radiation synthesis of superabsorbent poly(acrylic acid)-carrageenan hydrogels

    NASA Astrophysics Data System (ADS)

    Francis, Sanju; Kumar, Manmohan; Varshney, Lalit

    2004-04-01

    A series of superabsorbent hydrogels were prepared from carrageenan and partially neutralized acrylic acid by gamma irradiation at room temperature. The gel fraction, swelling kinetics and the equilibrium degree of swelling (EDS) of the hydrogels were studied. It was found that the incorporation of even 1% carrageenan (sodium salt) increases the EDS of the hydrogels from ˜320 to ˜800 g/g. Thermal analysis were carried out to determine the amount of free water and bound water in the hydrogels. Under optimum conditions, poly(acrylic acid)-carrageenan hydrogels with high gel fraction (˜80%) and very high EDS (˜800 g/g) were prepared gamma radiolytically from aqueous solution containing 15% partially neutralized acrylic acid and 1-5% carrageenan. The hydrogels were also found to be sensitive to the pH and the ionic strength of the medium.

  16. FT-IR and FT-Raman studies of cross-linking processes with Ca(2+) ions, glutaraldehyde and microwave radiation for polymer composition of poly(acrylic acid)/sodium salt of carboxymethyl starch--part I.

    PubMed

    Grabowska, Beata; Sitarz, Maciej; Olejnik, Ewa; Kaczmarska, Karolina

    2015-01-25

    FT-IR and FT-Raman spectroscopic methods allowed to identify the cross-linking process of the aqueous composition of poly(acrylic acid)/sodium salt of carboxymethyl starch (PAA/CMS-Na) applied as a binder for moulding sands. The cross-linking was performed by chemical methods by introducing cross-linking substances with Ca(2+) ions or glutaraldehyde and by physical way, applying the microwave radiation. It was found that Ca(2+) ions cause formation of cross-linking ionic bonds within carboxyl and carboxylate groups. Glutaraldehyde generates formation of cross-linking bonds with hemiacetal and acetal structures. Whereas in the microwave radiation field, due to dehydration, lattices are formed by anhydride bonds.

  17. FT-IR and FT-Raman studies of cross-linking processes with Ca2+ ions, glutaraldehyde and microwave radiation for polymer composition of poly(acrylic acid)/sodium salt of carboxymethyl starch - Part I

    NASA Astrophysics Data System (ADS)

    Grabowska, Beata; Sitarz, Maciej; Olejnik, Ewa; Kaczmarska, Karolina

    2015-01-01

    FT-IR and FT-Raman spectroscopic methods allowed to identify the cross-linking process of the aqueous composition of poly(acrylic acid)/sodium salt of carboxymethyl starch (PAA/CMS-Na) applied as a binder for moulding sands. The cross-linking was performed by chemical methods by introducing cross-linking substances with Ca2+ ions or glutaraldehyde and by physical way, applying the microwave radiation. It was found that Ca2+ ions cause formation of cross-linking ionic bonds within carboxyl and carboxylate groups. Glutaraldehyde generates formation of cross-linking bonds with hemiacetal and acetal structures. Whereas in the microwave radiation field, due to dehydration, lattices are formed by anhydride bonds.

  18. High-Performance Flexible Solid-State Carbon Cloth Supercapacitors Based on Highly Processible N-Graphene Doped Polyacrylic Acid/Polyaniline Composites

    PubMed Central

    Wang, Yongguang; Tang, Shaochun; Vongehr, Sascha; Ali Syed, Junaid; Wang, Xiangyu; Meng, Xiangkang

    2016-01-01

    Improving the solubility of conductive polymers to facilitate processing usually decreases their conductivity, and they suffer from poor cycling stability due to swelling-shrinking during charging cycles. We circumvent these problems with a novel preparation method for nitrogen-doped graphene (NG) enhanced polyacrylic acid/polyaniline (NG-PAA/PANI) composites, ensuring excellent processibility for scalable production. The content of PANI is maximized under the constraint of still allowing defect-free coatings on filaments of carbon cloth (CC). The NG content is then adjusted to optimize specific capacitance. The optimal CC electrodes have 32 wt.% PANI and 1.3 wt.% NG, thus achieving a high capacitance of 521 F/g at 0.5 F/g. A symmetric supercapacitor made from 20 wt.% PANI CC electrodes has more than four times the capacitance (68 F/g at 1 A/g) of previously reported flexible capacitors based on PANI-carbon nanotube composites, and it retains the full capacitance under large bending angles. The capacitor exhibits high energy and power densities (5.8 Wh/kg at 1.1 kW/kg), a superior rate capability (still 81% of the 1 A/g capacitance at 10 A/g), and long-term electrochemical stability (83.2% retention after 2000 cycles). PMID:26883179

  19. High-Performance Flexible Solid-State Carbon Cloth Supercapacitors Based on Highly Processible N-Graphene Doped Polyacrylic Acid/Polyaniline Composites

    NASA Astrophysics Data System (ADS)

    Wang, Yongguang; Tang, Shaochun; Vongehr, Sascha; Ali Syed, Junaid; Wang, Xiangyu; Meng, Xiangkang

    2016-02-01

    Improving the solubility of conductive polymers to facilitate processing usually decreases their conductivity, and they suffer from poor cycling stability due to swelling-shrinking during charging cycles. We circumvent these problems with a novel preparation method for nitrogen-doped graphene (NG) enhanced polyacrylic acid/polyaniline (NG-PAA/PANI) composites, ensuring excellent processibility for scalable production. The content of PANI is maximized under the constraint of still allowing defect-free coatings on filaments of carbon cloth (CC). The NG content is then adjusted to optimize specific capacitance. The optimal CC electrodes have 32 wt.% PANI and 1.3 wt.% NG, thus achieving a high capacitance of 521 F/g at 0.5 F/g. A symmetric supercapacitor made from 20 wt.% PANI CC electrodes has more than four times the capacitance (68 F/g at 1 A/g) of previously reported flexible capacitors based on PANI-carbon nanotube composites, and it retains the full capacitance under large bending angles. The capacitor exhibits high energy and power densities (5.8 Wh/kg at 1.1 kW/kg), a superior rate capability (still 81% of the 1 A/g capacitance at 10 A/g), and long-term electrochemical stability (83.2% retention after 2000 cycles).

  20. A stencil printed, high energy density silver oxide battery using a novel photopolymerizable poly(acrylic acid) separator.

    PubMed

    Braam, Kyle; Subramanian, Vivek

    2015-01-27

    A novel photopolymerized poly(acrylic acid) separator is demonstrated in a printed, high-energy-density silver oxide battery. The printed battery demonstrates a high capacity of 5.4 mA h cm(-2) at a discharge current density of 2.75 mA cm(-2) (C/2 rate) while delivering good mechanical flexibility and robustness.

  1. Virucidal efficacy of a combination of 0.2% peracetic acid and 80% (v/v) ethanol (PAA-ethanol) as a potential hand disinfectant.

    PubMed

    Wutzler, P; Sauerbrei, A

    2000-12-01

    The formulation PAA-ethanol, consisting of 0.2% paracetic acid (PAA) and 80% ethanol, was tested for its virucidal activity on the enveloped vaccinia virus and papova virus SV 40 and the non-enveloped adenovirus type 2 and poliovirus type 1. All test viruses were inactivated by PAA-ethanol within an exposure time of 1 minute, as measured by a log(10)reduction of 4 in virus titres. It was shown that poliovirus type 1 can be inactivated by PAA-ethanol within 1 min, whilst for the aqueous 0.2% PAA solution, an exposure time of 5 min is necessary. As shown by electron microscopic observation, the structure of virus particles was completely destroyed by 0.2% PAA within 15 min. The broad antimicrobial spectrum including a high virucidal activity, short exposure time and no toxic or allergenic decomposition products are favourable prerequisites for the medical use of PAA-ethanol and it warrants further investigation as a hand disinfectant. Copyright 2000 The Hospital Infection Society.

  2. Pervaporation separation of binary organic-aqueous liquid mixtures using crosslinked PVA membranes. I. Characterization of the reaction between PVA and PAA

    SciTech Connect

    Jiwon Rhim; Kewho Lee . Membranes and Separation Lab.); Minyoung Sohn; Hyeokjong Joo . Dept. of Polymer Science and Engineering)

    1993-10-20

    For the purpose of the water-selective membrane material development for pervaporation separation, poly(vinyl alcohol) (PVA) was crosslinked with a low molecular weight of poly(acrylic acid) (PAA). The crosslinking reactions between PVA and PAA were characterized through IR spectroscopy, differential scanning calorimetry (DSC), and tensile tests when varying the reaction conditions, that is, time, temperature, amounts of cross-linking agents, PAA. It was found that the crosslinking reaction was fast: in other words, that the reaction mainly occurred at the initial step of each reaction condition. The best reaction conditions for preparing the crosslinked PVA membranes were found to be: reaction time not over 1 h, reaction temperature in the range of 150-180 C. PAA contents of 15-20 wt% were found satisfactory with respect to the application areas.

  3. Synthesis and characterization of zinc chloride containing poly(acrylic acid) hydrogel by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Park, Jong-Seok; Kuang, Jia; Gwon, Hui-Jeong; Lim, Youn-Mook; Jeong, Sung-In; Shin, Young-Min; Seob Khil, Myung; Nho, Young-Chang

    2013-07-01

    In this study, the characterization of zinc chloride incorporated into a poly(acrylic acid) (PAAc) hydrogel prepared by gamma-ray irradiation was investigated. Zinc chloride powder with different concentrations was dissolved in the PAAc solution, and it was crosslinked with gamma-ray irradiation. The effects of various parameters such as zinc ion concentration and irradiation doses on characteristics of the hydrogel formed were investigated in detail for obtaining an antibacterial wound dressing. In addition, the gel content, pH-sensitive (pH 4 or 7) swelling ratio, and UV-vis absorption spectra of the zinc particles in the hydrogels were characterized. Moreover, antibacterial properties of these new materials against Staphylococcus aureus and Escherichia coli strains were observed on solid growth media. The antibacterial tests indicated that the zinc chloride containing PAAc hydrogels have good antibacterial activity.

  4. Poly(acrylic acid) microspheres loaded with lidocaine: preparation and characterization for arterial embolization.

    PubMed

    Cui, Dai-Chao; Lu, Wan-Liang; Sa, Er-A; Gu, Meng-Jie; Lu, Xiao-Jing; Fan, Tian-Yuan

    2012-10-15

    A new embolic agent, poly(acrylic acid) microspheres (PMs), was synthesized and the cytocompatibility was proved by mouse L929 fibroblast cells. An analgesic drug, lidocaine, was loaded on the PMs to relief pain caused by embolization. PMs and lidocaine loaded microspheres (LMs) were characterized by investigating infrared spectrum, morphology, particle size, and equilibrium water contents (EWC). A series of tests were employed to evaluate the elasticity of PMs, LMs and Embosphere™, including once compression, twice compression, and stress relaxation test. The pressures of PMs and LMs passing through a catheter were measured on line by our new designed device. Drug release was studied with T-cell apparatus. The properties of PMs and LMs were proved to be suitable for embolization. Both PMs and LMs in this study might be potential embolic agents in the future. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Hydrogels from Amorphous Calcium Carbonate and Polyacrylic Acid: Bio-Inspired Materials for "Mineral Plastics".

    PubMed

    Sun, Shengtong; Mao, Li-Bo; Lei, Zhouyue; Yu, Shu-Hong; Cölfen, Helmut

    2016-09-19

    Given increasing environmental issues due to the large usage of non-biodegradable plastics based on petroleum, new plastic materials, which are economic, environmentally friendly, and recyclable are in high demand. One feasible strategy is the bio-inspired synthesis of mineral-based hybrid materials. Herein we report a facile route for an amorphous CaCO3 (ACC)-based hydrogel consisting of very small ACC nanoparticles physically cross-linked by poly(acrylic acid). The hydrogel is shapeable, stretchable, and self-healable. Upon drying, the hydrogel forms free-standing, rigid, and transparent objects with remarkable mechanical performance. By swelling in water, the material can completely recover the initial hydrogel state. As a matrix, thermochromism can also be easily introduced. The present hybrid hydrogel may represent a new class of plastic materials, the "mineral plastics". © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Preparation of nanofiber polythiophene layered on Ba x Sr1- x Fe12O19/Fe3O4/polyacrylic acid core-shell structure and its microwave absorption investigation

    NASA Astrophysics Data System (ADS)

    Hosseini, Seyed Hossein; Moloudi, Maryam

    2015-09-01

    Ba x Sr1- x Fe12O19/Fe3O4/polyacrylic acid/polythiophene (Ba x Sr1- x Fe12O19/Fe3O4/PAA/PTh) nanocomposites with multi-core-shell structure were successfully synthesized by four steps. The samples were characterized by FTIR, X-ray diffraction (XRD), transmission electron microscope (TEM), vibrating sample magnetometer, and radar absorbing material reflectivity far-field radar cross-section method, respectively. XRD and TEM results indicated that the obtained nanoparticles have multi-core-shell morphology. The magnetic properties and microwave absorption analyses reveal that there are interphase interactions at the interface of Ba x Sr1- x Fe12O19, Fe3O4, PAA, and PTh, which can affect the magnetic properties and microwave absorption properties of the samples. The microwave-absorbing properties of nanocomposites were investigated at 8-14 GHz. A typical layer absorber exhibited an excellent microwave absorption with a -26 dB maximum absorption at 14 GHz. Compared with core material, the coercivity and saturation magnetization of multi-core-shell nanocomposites decrease obviously, but the microwave absorption properties of nanocomposites are improved greatly. The results show that these composite could be used as advancing absorption and shielding materials due to their favorable microwave-absorbing properties.

  7. Salt formation in solid dispersions consisting of polyacrylic acid as a carrier and three basic model compounds resulting in very high glass transition temperatures and constant dissolution properties upon storage.

    PubMed

    Weuts, Ilse; Kempen, Dieter; Verreck, Geert; Peeters, Jef; Brewster, Marcus; Blaton, Norbert; Van den Mooter, Guy

    2005-01-01

    The purpose of the study was to investigate the suitability of polyacrylic acid (PAA) as a carrier in solid dispersions, with the aim to delay crystallization of basic drugs and improve their dissolution behaviour. The physicochemical properties were investigated in order to link the physical state of some model compounds to their dissolution properties. Loperamide and two structurally related substances were selected as model compounds. Solid dispersions were prepared by spray drying. The amount of residual solvents and water was determined with gas chromatography (GCS: S: solvent) and thermogravimetric analysis (TGA). The drug loading of the dispersions was determined using high performance liquid chromatography (HPLC). ADSC (alternating or temperature modulated DSC), XRD and FT-IR-spectroscopy were used to evaluate the physical state and in vitro dissolution tests were performed to measure the dissolution properties. IR-measurements demonstrated the formation of a salt between the COOH-groups of the polymer and the amino-groups of the compounds. This phenomenon results in high T(g)-values of the dispersions, suppression of crystallization of the fragment molecules during preparation and an increase of the dissolution rate. Furthermore, the stability study conducted on the dispersions with loperamide showed that both, the amorphous state of the drug and the dissolution behaviour are stable under the applied storage conditions. Hence, from the experimental results it could be concluded that PAA is a suitable carrier in the formulation of stable solid dispersions for the basic compounds that were investigated.

  8. N,N'-methylenebis(acrylamide)-crosslinked poly(acrylic acid) particles as doxorubicin carriers: A comparison between release behavior of physically loaded drug and conjugated drug via acid-labile hydrazone linkage.

    PubMed

    Modarresi-Saryazdi, Seyedeh Mahnaz; Haddadi-Asl, Vahid; Salami-Kalajahi, Mehdi

    2017-09-18

    N,N'-methylenebis(acrylamide) (MBA)-crosslinked poly(acrylic acid) (PAA) particles with low degree of cross-linking were synthesized using distillation precipitation polymerization. Size and size distribution of particles were obtained using dynamic light scattering and field emission scanning electron microscopy( and results showed that microspheres had a narrow size dispersity. Proton nuclear magnetic resonance results indicated that amount of cross-linker in structure of particles is a little more than the molar percentage of feeded MBA because of greater activity ratio of MBA than AA. pH-responsive behavior of samples was investigated using UV-vis. absorption at 480 nm where each sample showed a sudden deplete in UV absorbance at a peculiar pH. Synthesized particles were used as carriers of anti-cancer drug doxorubicin using two different approaches including physically loading of drug and drug conjugation via an acid-labile hydrazone linkage. Release results showed that in the first case, amount of released drug has an inverse relationship with the amount of cross-linker in the structure and also, by adding an acid-labile linkage, the amount of burst release decreased drastically. Also, the amount of released drug for conjugated systems was much lesser than particles with physically loaded drug. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2017. © 2017 Wiley Periodicals, Inc.

  9. Polyelectrolyte conformational transition in aqueous solvent mixture influenced by hydrophobic interactions and hydrogen bonding effects: PAA-water-ethanol.

    PubMed

    Sappidi, Praveenkumar; Natarajan, Upendra

    2016-03-01

    Molecular dynamics simulations of poly(acrylic acid) PAA chain in water-ethanol mixture were performed for un-ionized and ionized cases at different degree-of-ionization 0%, 80% and 100% of PAA chain by Na(+) counter-ions and co-solvent (ethanol) concentration in the range 0-90vol% ethanol. Aspects of structure and dynamics were investigated via atom pair correlation functions, number and relaxation of hydrogen bonds, nearest-neighbor coordination numbers, and dihedral angle distribution function for back-bone and side-groups of the chain. With increase in ethanol concentration, chain swelling is observed for un-ionized chain (f=0) and on the contrary chain shrinkage is observed for partially and fully ionized cases (i.e., f=0.8 and 1). For un-ionized PAA, with increase in ethanol fraction ϕeth the number of PAA-ethanol hydrogen bonds increases while PAA-water decreases. Increase in ϕeth leads to PAA chain expansion for un-ionized case and chain shrinkage for ionized case, in agreement with experimental observations on this system. For ionized-PAA case, chain shrinkage is found to be influenced by intermolecular hydrogen bonding with water as well as ethanol. The localization of ethanol molecules near the un-ionized PAA backbone at higher levels of ethanol is facilitated by a displacement of water molecules indicating presence of specific ethanol hydration shell, as confirmed by results of the RDF curves and coordination number calculations. This behavior, controlled by hydrogen bonding provides a significant contribution to such a conformational transition behavior of the polyelectrolyte chain. The interactions between counter-ions and charges on the PAA chain also influence chain collapse. The underlying origins of polyelectrolyte chain collapse in water-alcohol mixtures are brought out for the first time via explicit MD simulations by this study.

  10. pH-Responsive Behavior of Poly(acrylic acid) Brushes of Varying Thickness

    NASA Astrophysics Data System (ADS)

    Yadav, Vivek; Robertson, Megan; Conrad, Jacinta

    2015-03-01

    We have investigated the pH-dependent response of polyelectrolyte brushes of varying thickness. Our model system consists of poly(acrylic acid) brushes, which change from hydrophobic and neutral at low pH to hydrophilic and negatively charged at high pH, synthesized using a grafting-from approach at constant grafting density. As the polymer brush thickness increased, the brushes exhibited greater hysteresis in static water contact angle as a function of pH. We extracted the pKa of the polymer brushes from contact angle measurements. The relationship between the pKa and brush thickness depended on the order in which the brushes were exposed to solutions of varying pH: pKa decreased on increasing brush thickness when going from basic to acidic medium whereas pKa increased on increasing brush thickness when going from acidic to basic medium. We speculate that the origin of hysteresis can be explained by pH-dependent conformational changes in these polyelectrolyte brushes.

  11. Evaluation of poly(acrylic acid-co-ethylhexyl acrylate) films for mucoadhesive transbuccal drug delivery: factors affecting the force of mucoadhesion.

    PubMed

    Shojaei, A H; Paulson, J; Honary, S

    2000-07-03

    Based on the premise that similar surface properties between the adhesive and the substrate would yield a strong adhesive bond, copolymers of acrylic acid (AA) and 2-ethylhexyl acrylate (EHA), P(AA-co-EHA), were designed and synthesized for buccal mucoadhesion. A series of linear copolymers with varying feed ratios of the two monomers (AA and EHA) were synthesized through free radical copolymerization at 69+/-0.5 degrees C using azobis(isobutyronitrile) (AIBN) as initiator. The reactions were carried out in THF under nitrogen for 24 h. The glass transition temperatures, T(g), of the copolymers were determined using DSC. The adhesion studies were conducted to determine the effects of copolymer composition, contact time between the substrate and the adhesive, and crosshead speed on mucoadhesive performance of the copolymer films using a computer interfaced Instron material testing system. The glass transition temperature of the copolymers decreased with increasing EHA content. Wet glass surface as substrate was shown not to be a good substrate model for adhesion determination studies. The copolymer composed of 46:54 mol.% AA:EHA (an almost 1:1 ratio in the repeat units) yielded the highest mucoadhesive force in contact with porcine buccal mucosa which was significantly greater (P<0.05) than that of poly(acrylic acid) (PAA) (used as positive control). The mucoadhesive force for all copolymers studied was significantly (P<0.05) greater than that of the negative control (backing material without copolymer film) except for the EHA homopolymer. Crosshead speed increased mucoadhesive force linearly and had a more pronounced effect on the mucoadhesive performance than time of contact between the adhesive and the substrate.

  12. The synthesis and in vitro characterization of the mucoadhesion and swelling of poly(acrylic acid) hydrogels.

    PubMed

    Warren, S J; Kellaway, I W

    1998-05-01

    The purpose of this research was to synthesize insoluble, mucoadhesive hydrogels by crosslinking linear poly(acrylic acid) with sucrose and investigate the relationship between hydrogel crosslink density, swelling, and in vitro mucoadhesion. A condensation reaction was employed to synthesize the hydrogels and crosslink density was varied by altering sucrose concentration and cure time. Equilibrium swelling at pH 7.4 was measured both gravimetrically and geometrically. In vitro mucoadhesion was determined by a tensile technique. Equilibrium swelling studies indicated that the crosslink density was proportional to both sucrose concentration and duration of cure time. In vitro mucoadhesive properties of the hydrogels improved as crosslink density increased. This was attributed to an increase in poly(acrylic acid) chain density/unit area of the equilibrium swollen hydrogel, which promoted interaction of the mucoadhesive and glycoprotein polymer chains.

  13. Protein absorption and fouling on poly(acrylic acid)-graft-polypropylene microfiltration membrane

    NASA Astrophysics Data System (ADS)

    Liu, Yanjun; Ma, Huiying; Lv, Chunying; Yang, Jia; Fu, Xueqi

    2009-07-01

    A series of pH-sensitive poly (acrylic acid)-graft-polypropylene hollow fiber microfiltration membranes were prepared by UV-photo-irradiation. Bovine serum albumin (BSA) was chosen as the model protein to investigate its absorption and fouling behaviors on membranes. The results showed that the hydrophilicity of grafted membrane was improved by poly(acrylic acid) chains with parts of membrane pores blocked. The grafted membranes were markedly pH-dependent on the water permeability as pH was altered from 1 to 11. The zeta potential of grafted membranes calculated by streaming potential was negative in most pH range. Electrostatic interaction energy calculated by DLVO theory showed the electric interaction force between grafted membrane and BSA was attractive. With the rise of grafting degree, the electric attractive force between grafted membrane and BSA increased as pH=3 and decreased as pH=8, while it kept basically unchanged as pH=4.7. As a result, most serious fouling was observed as pH=4.7. Grafted membranes had a lower BSA absorption and better antifouling behavior as pH=8, while the opposite result was revealed as pH=3. In conclusion, the absorption and fouling behavior of BSA on membranes was pH-dependent due to the pH-dependence of membrane charge, and the conformation of BSA and grafting chains.

  14. A spiral designed surface based on amino-perylene grafted polyacrylic acid.

    PubMed

    Celia, Elena; Amigoni, Sonia; Taffin de Givenchy, Elisabeth; Pieters, Gregory; Gaucher, Anne; Prim, Damien; Audibert, Jean-Frederic; Méallet-Renault, Rachel; Pansu, Robert; Guittard, Frédéric

    2014-10-18

    This communication shows the possibility of inducing spontaneous special surface organisation by means of grafting a fluorescent aminobenzo[g,h,i]perylene derivative onto surface grown polyacrylic chains.

  15. Osmotic Engine: Translating Osmotic Pressure into Macroscopic Mechanical Force via Poly(Acrylic Acid) Based Hydrogels

    PubMed Central

    Arens, Lukas; Weißenfeld, Felix; Klein, Christopher O.; Schlag, Karin

    2017-01-01

    Poly(acrylic acid)‐based hydrogels can swell up to 100–1000 times their own weight in desalinated water due to osmotic forces. As the swelling is about a factor of 2–12 lower in seawater‐like saline solutions (4.3 wt% NaCl) than in deionized water, cyclic swelling, and shrinking can potentially be used to move a piston in an osmotic motor. Consequently, chemical energy is translated into mechanical energy. This conversion is driven by differences in chemical potential and by changes in entropy. This is special, as most thermodynamic engines rely instead on the conversion of heat into mechanical energy. To optimize the efficiency of this process, the degree of neutralization, the degree of crosslinking, and the particle size of the hydrogels are varied. Additionally, different osmotic engine prototypes are constructed. The maximum mean power of 0.23 W kg−1 dry hydrogel is found by using an external load of 6 kPa, a polymer with 1.7 mol% crosslinking, a degree of neutralization of 10 mol%, and a particle size of 370–670 µm. As this is achieved only in the first round of optimization, higher values of the maximum power average over one cycle seem realistic. PMID:28932675

  16. Element-Doped Polyacrylic Acid Thin Films as SIMS Standards for Organic Materials

    NASA Astrophysics Data System (ADS)

    Davisson, M.; Phinney, D. L.; Weber, P. K.

    2009-12-01

    To constrain relative sensitive factors for SIMS elemental analysis of organic materials, calibration standards are being developed by coordinating ppm quantities of Group I, Group II, and transition metals with polyacrylic acid resin and depositing them as thin films. Each element is prepared as an aqueous acetate, oxalate, or nitrate solution to avoid unwanted elements that compromise thin film uniformity or produce interfering masses. These are subsequently mixed proportionally with reagent grade resins (Mw ~2000 and ~50,000), and dried passively on an Al bullet or spin-coated for thin layering (~100nm). Initial results using an O- primary beam on a Cameca NanoSIMS demonstrate excellent lateral homogeneity for Na, K, Fe, Co, and Cd at nanometer scale and consistent ratios to 12C (stdev <10%) over multiple 10um raster areas, whereas Mg, Ca, Sr, and Cu show variable ratios to 12C over sputter depth (stdev >10%). Depth profiling over the entire film thickness using a Cameca 3f show high reproducibility of element trends at 250um raster areas. Additional measurements will incorporate multi-element suites of biologically-relevant species (e.g. Na, K, Ca, P) to facilitate quantitative analysis of sensitivity factors with compositional changes.

  17. Kinetics study of phase separation in polyacrylic acid/nematic LC system by optical technique

    NASA Astrophysics Data System (ADS)

    Mucha, Maria; Krolikowski, Z.

    2002-06-01

    Thin polymer layers containing liquid crystal LC of non- linear optical properties were obtained from polyacrylic acid. Samples were produced by phase separation as a consequence of chemical polymerization (PIPS method) resulting in precipitation of liquid crystals in the form of droplets in a polymer matrix being formed. Films were produced in variable conditions of polymerization time and temperature and different content of an initiator (1 - 3 wt%). They contained of 10 - 40 wt% of LC. The cell thickness was constant and equal to 20 micrometers . Systems obtained in this way were subjected to thermo-optical and electro-optical studies, morphological structure investigation and DSC analysis. The polymerization time has a significant influence on the size and number of LC droplets. The presence of benzoyl peroxide can cause partial destruction of LC properties which is reflected by a decrease of isotropization temperature TI of the liquid crystal. An increase of the initiator amount shortens the time of polymerization (ti), while process enthalpy ((Delta) H) increases. Hence, the liquid crystal separation time decreases as well. Films prepared by this method present good electro-optical properties. Rise and decay times of orientation are short and equal to 2 - 17 ms (depending on driving voltage applied) and about 80 ms, respectively. Threshold voltage for the best sample is equal to 5 V. Optimal conditions are found: LC content equals 20%, wt(i) equals 1%, polymerization temperature Tp equals 100 - 110 degree(s)C.

  18. A novel poly(acrylic acid-co-acrylamide)/diatomite composite flocculant with outstanding flocculation performance.

    PubMed

    Xu, Kun; Liu, Yao; Wang, Yang; Tan, Ying; Liang, Xuecheng; Lu, Cuige; Wang, Haiwei; Liu, Xiusheng; Wang, Pixin

    2015-01-01

    Series of anionic flocculants with outstanding flocculation performance, poly(acrylic acid-co-acrylamide)/diatomite composite flocculants (PAAD) were successfully prepared through aqueous solution copolymerization and applied to flocculate from oil-field fracturing waste-water. The structure of PAAD was characterized by Fourier transform infra-red spectroscopy, (13)C nuclear magnetic resonance and X-ray diffraction tests, and its properties were systematically evaluated by viscometer, thermogravimetry analysis and flocculation measurements. Furthermore, the influences of various reaction parameters on the apparent viscosity of flocculant solution were studied, and the optimum synthesis condition was determined. The novel composite flocculants exhibited outstanding flocculation properties. Specifically, the dosage of composite flocculants that could make the transmittance of treated wastewater exceed 90% was only approximately 12-35 ppm, which was far lower than that of conventional flocculants. Meanwhile, the settling time was lower than 5 s, which was similar to that of conventional flocculants. This was because PAAD flocculants had a higher absorption capacity, and larger chain extending space than conventional linear flocculants, which could refrain from the entanglement of linear polymer chains and significantly improve flocculation capacity.

  19. Modification of polyethylene by radiation-induced graft polymerization of acrylic acid

    NASA Astrophysics Data System (ADS)

    Sidorova, L. P.; Aliev, A. D.; Zlobin, V. B.; Aliev, R. E.; Chalykh, A. E.; Kabanov, V. Ya.

    The kinetics investigation of the radiation-induced graft polymerization of acrylic acid onto low density polyethylene by direct method in aqueous solution in the presence of Mohr's salt, was performed. The technique of the contrasting of polyacrylic acid (PAA) graft layer was worked out by Ag +-ions. The structural and morphological peculiarities of grafted copolymers of PE with PAA were determined by the method of electron probe, and X-ray microanalysis by means of the electron microscopy.

  20. In-situ polymerization approach for preparation of rare earth fluoride phosphors coated with PAA.

    PubMed

    Li, Xie; Zhou, Xingping; Wang, Xiaqin

    2011-11-01

    Up-conversion nanoparticles (UCNPs), which can convert a radiation from a longer wavelength to a shorter wavelength, have great potential uses as bio-labels in biological detection. However, these NPs usually cannot be used directly unless their surfaces are further modified. In this paper, NaYF4:Yb, Er nanoparticles (NPs) were coated with poly(acrylic acid) (PAA) by in situ polymerization for the first time. Accordingly, NaYF4:Yb, Er/NaYF4 NPs were synthesized before PAA coating to avoid the decay of optical intensity. The resulting UCNPs were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and up-conversion photoluminescence spectrometry. The XRD results indicated that the resultant UCNPs exhibited a pure hexagonal phase. The FT-IR spectra and TGA curves revealed that these NPs were coated successfully with PAA. Meanwhile, the TEM results showed that well-dispersed UCNPs with the best morphology and an average size of about 90 nm were obtained with 8.0 wt% acrylic acid content (the content percentage in the whole reaction system) at 0 degrees C within 130 min. Fluorescence tests showed that the UCNPs had a strong UC fluorescence intensity. Settlement tests revealed that PAA-coated NaYF4 UCNPs had more favorable dispersion stability than uncoated UCNPs in an aqueous system. These functionalized nanocomposites could be used for further bio-conjugation.

  1. Light scattering study of partially ionized poly(acrylic acid) systems : comparison between gels and solutions

    NASA Astrophysics Data System (ADS)

    Moussaid, A.; Munch, J. P.; Schosseler, F.; Candau, S. J.

    1991-06-01

    Static and quasielastic light scattering experiments have been performed on the reaction bath of partially neutralized poly(acrylic acid) solutions and gels. The intensity scattered from gels is independent on the scattering wavevector, giving thus evidence that the gels are homogeneous at the scale of the wavelength of the light, contrary to what is generally observed in neutral gels. The comparison of the time and ensemble averages of the autocorrelation function of scattered light intensity shows that the gels behave with respect to that experiment as ergodic media. The variations of the intensity scattered from gels and solutions, with the ionization degree and the polymer concentration were found to be in good agreement with those predicted from simple theoretical arguments. The variations of the cooperative diffusion with these same parameters were found similar for gels and solutions. Des mesures de diffusion statique et quasiélastique de la lumière ont été effectuées sur des solutions et des gels d'acide poly(acrylique) partiellement ionisés. L'intensité diffusée par les gels est indépendante du vecteur d'onde de transfert, ce qui montre leur homogénéité, contrairement au cas des gels neutres. La comparaison des moyennes temporelle et spatiale de la fonction d'autocorrélation de l'intensité de la lumière diffusée montre que ces gels se comportent comme des milieux ergodiques. Les variations de l'intensité diffusée par les gels et les solutions en fonction de la concentration en polymère et du degré d'ionisation sont en bon accord avec les prédictions théoriques. Les variations du coefficient de diffusion avec ces mêmes paramètres sont identiques pour les gels et les solutions.

  2. Preparation of poly(acrylic acid) modified polyurethane membrane for biomaterial by UV radiation without degassing.

    PubMed

    Yang, J M; Huang, M J; Yeh, T S

    1999-05-01

    Poly(acrylic acid) modified polyurethane (AA/PU) membranes were prepared by UV radiation without degassing. The chemical composition of the AA/PU membrane was studied by IR spectroscopy. In addition to those absorption peaks associated with pure PU, the absorption peak at 2400 cm-1 of poly(AA) was also found. The morphology of AA/PU membrane was studied by optical polarizing microscopy. We also measured the glass transition temperature and the decomposition temperature of the AA/PU membrane by differential scanning calorimetry and thermogravimetric analysis. A significant domain was found in the AA/PU membrane, which resulted in different glass transition temperature and decomposition temperature between AA/PU and pure PU membrane. The effect of AA content on the contact angle and water absorption of the AA/PU membrane was determined. It was found that the water content of AA/PU membrane increased with increasing AA content, whereas the contact angle decreased. By using Kaeble's equation and the contact angle data, the surface free energy of AA/PU membrane was determined. The increase of surface free energy resulted from the increase of the dispersion (gammad) term and polar (gammap) term. In order to evaluate the biocompatibility of these membranes, a cytotoxicity test and a cell adhesion and proliferation assay were conducted in cell culture. Immortal cells and primary lymphocytes were both used in this study. The results showed that these AA/PU membranes exhibited very low cytotoxicity and could support cell adhesion and growth. An animal primary test was also done in this study. It was found that the AA/PU membrane could possibly be employed in the treatment of bowel defect. Copyright 1999 John Wiley & Sons, Inc.

  3. Understanding Humic Acid / Zr(IV) Interaction - A Spectromicroscopy Approach

    SciTech Connect

    Rothe, Joerg; Plaschke, Markus; Denecke, Melissa A.

    2007-02-02

    Complexation of Zr(IV) by humic acid (HA) and polyacrylic acid (PAA) is investigated from the point of view of the organic ligand. STXM Spectromicroscopy and C 1s-NEXAFS point to different interaction mechanisms between Zr(IV) cations and oxo/hydroxo colloids and PAA. Under conditions where the metal aquo ion is stable, strong complexes are formed. In contrast, unspecific surface coating is identified when PAA is contacted with Zr(IV) oxo/hydroxide colloids. HA exhibits similar C 1s-NEXAFS features indicating a complexation reaction.

  4. Synthesis and high-efficiency methylene blue adsorption of magnetic PAA/MnFe2O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Ding, Zui; Cai, Minhan; Jian, Haitao; Zeng, Zhiqiao; Li, Feng; Liu, J. Ping

    2015-08-01

    MnFe2O4 nanoparticles and polyacrylic acid PAA/MnFe2O4 nanocomposites were synthesized by a hydrothermal method and ultrasonic mixing process. The obtained materials were characterized by XRD, FTIR, SEM, TEM, and VSM. XRD patterns indicate that the synthesized MnFe2O4 nanoparticles have a single cubic spinel phase. SEM images confirm the existence of three types of basic morphology of MnFe2O4 nanoparticles: octahedral, flower-like, and plate-like particles. High saturation magnetization Ms (up to 74.6 emu/g) of the as-synthesized MnFe2O4 nanoparticles was obtained. Experiments demonstrate that the variation of the hydrothermal reaction time does not remarkably affect the magnetic properties of MnFe2O4 nanoparticles. In PAA/MnFe2O4 nanocomposites, the coating of PAA leads to a slight decrease in magnetization of MnFe2O4 nanoparticles. Additionally, PAA coating greatly enhances the adsorption properties of MnFe2O4 nanoparticles for Methylene Blue (MB) dye. Especially, the removal efficiency reaches 96.3%. This research indicates that the as-synthesized PAA/MnFe2O4 nanocomposites exhibit excellent magnetic properties and can be taken as a promising adsorbent for removal of MB dye in industrial scale.

  5. A simplified method for synthesis of Fe3O4@PAA nanoparticles and its application for the removal of basic dyes

    NASA Astrophysics Data System (ADS)

    Xu, Yin-Yin; Zhou, Min; Geng, Hui-Juan; Hao, Jun-Jie; Ou, Qian-Qian; Qi, Sheng-Da; Chen, Hong-Li; Chen, Xing-Guo

    2012-02-01

    A simplified method for synthesis of polyacrylic acid-bound iron oxide magnetic nanoparticles (Fe3O4@PAA NPs) was reported. The as-prepared nanoparticles were characterized by TEM, FT-IR, VSM and XRD. Characterization results indicated that PAA was successfully introduced onto the surface of Fe3O4 and did not cause any changes in magnetic property. The Fe3O4@PAA NPs were used to adsorb rhodamine 6G (R6G) as a model basic dye pollutant from aqueous solution. Kinetics data and adsorption isotherms were better fitted by pseudo-second-order kinetic model and Langmuir isotherm, respectively. The adsorption equilibrium could be reached at about 20 min, showing that the as-prepared adsorbent exhibited extremely rapid adsorption rate. The aqueous solution of the Yellow River was chosen as the test sample, and the results showed that the magnetic adsorbent was efficient for the removal of the basic dye in the real sample.

  6. The formation of hydroxyapatite-calcium polyacrylate composites.

    PubMed

    Watson, K E; Tenhuisen, K S; Brown, P W

    1999-04-01

    Tetracalcium phosphate (TetCP, Ca4(PO4)2O) reacts rapidly with polyacrylic acid (PAA). Complete reaction results in the formation of hydroxyapatite (HAp) and calcium polyacrylate. Consequently, this combination of reactants can react to form a dental cement. However, reaction occurs so rapidly that it would be difficult to achieve a homogeneous mixture of reactants suitable for use in restorations. In order to explore extending the working time, the effects of prehydrating the TetCP to form surface layers of HAp on the TetCP particles was explored. Prehydration was found to be an effective means of allowing workability. Therefore, the effects of the proportions of TetCP and PAA, with and without HAp filler, on cement properties were investigated. The extents of the reactions were investigated by X-ray diffraction analysis; the extents of PAA neutralization were studied by Fourier transform infra-red spectroscopy (FTIR); pore structures were determined by mercury intrusion porosimetry; microstructures were observed by scanning microscopy, and compressive strengths were determined. After curing for 17 days at room temperature PAA neutralization was almost complete; however, residual TetCP could be detected by X-ray diffraction and PAA by FTIR. As expected, the compressive strengths of the cements showed a dependence on the liquid (water+polymer)-to-solid (TetCP+HAp filler) used. The presence of HAp filler caused a significant decrease in compressive strength and increasing the proportion of HAp filler resulted in a decrease in the compressive strength. The characteristics of the load-deflection curves showed a dependence on the presence of HAp filler. In the absence of filler, two slopes were observed in the curves whereas a linear curve, typical of a ceramic, was observed when HAp filler was present. Mercury intrusion porosimetry (MIP) indicated the majority of the porosity was present in pores larger than 0.1 microm. Porosity increased with increasing liquid

  7. Synthesis of hollow silver spheres using poly-(styrene-methyl acrylic acid) as templates in the presence of sodium polyacrylate

    NASA Astrophysics Data System (ADS)

    Wang, Aili; Yin, Hengbo; Ge, Chen; Ren, Min; Liu, Yumin; Jiang, Tingshun

    2010-02-01

    Hollow silver spheres were successfully prepared by reducing AgNO 3 with ascorbic acid and using negatively charged poly-(styrene-methyl acrylic acid) (PSA) spheres as templates in the presence of sodium polyacrylate as a stabilizer. Firstly, silver cations adsorbed on the surface of PSA spheres via electrostatic attraction between the carboxyl groups and silver cations were reduced in situ by ascorbic acid. The silver nanoparticles deposited on the surface of PSA spheres served as seeds for the further growth of silver shells. After that, extra amount of AgNO 3 and ascorbic acid solutions were added to form PSA/Ag composites with thick silver shells. In order to obtain compact silver shells, the as-prepared PSA/Ag composites were heated at 150 °C for 3 h. Then hollow silver spheres were prepared by dissolving PSA templates with tetrahydrofuran.

  8. Superparamagnetic iron oxide polyacrylic acid coated γ-Fe{sub 2}O{sub 3} nanoparticles do not affect kidney function but cause acute effect on the cardiovascular function in healthy mice

    SciTech Connect

    Iversen, Nina K.; Frische, Sebastian; Thomsen, Karen; Laustsen, Christoffer; Pedersen, Michael; Hansen, Pernille B.L.; Bie, Peter; Fresnais, Jérome; Berret, Jean-Francois; Baatrup, Erik; Wang, Tobias

    2013-01-15

    This study describes the distribution of intravenously injected polyacrylic acid (PAA) coated γ-Fe{sub 2}O{sub 3} NPs (10 mg kg{sup −1}) at the organ, cellular and subcellular levels in healthy BALB/cJ mice and in parallel addresses the effects of NP injection on kidney function, blood pressure and vascular contractility. Magnetic resonance imaging (MRI) and transmission electron microscopy (TEM) showed accumulation of NPs in the liver within 1 h after intravenous infusion, accommodated by intracellular uptake in endothelial and Kupffer cells with subsequent intracellular uptake in renal cells, particularly the cytoplasm of the proximal tubule, in podocytes and mesangial cells. The renofunctional effects of NPs were evaluated by arterial acid–base status and measurements of glomerular filtration rate (GFR) after instrumentation with chronically indwelling catheters. Arterial pH was 7.46 ± 0.02 and 7.41 ± 0.02 in mice 0.5 h after injections of saline or NP, and did not change over the next 12 h. In addition, the injections of NP did not affect arterial PCO{sub 2} or [HCO{sub 3}{sup −}] either. Twenty-four and 96 h after NP injections, the GFR averaged 0.35 ± 0.04 and 0.35 ± 0.01 ml min{sup −1} g{sup −1}, respectively, values which were statistically comparable with controls (0.29 ± 0.02 and 0.33 ± 0.1 ml{sup –1} min{sup –1} 25 g{sup –1}). Mean arterial blood pressure (MAP) decreased 12–24 h after NP injections (111.1 ± 11.5 vs 123.0 ± 6.1 min{sup −1}) associated with a decreased contractility of small mesenteric arteries revealed by myography to characterize endothelial function. In conclusion, our study demonstrates that accumulation of superparamagnetic iron oxide nanoparticles does not affect kidney function in healthy mice but temporarily decreases blood pressure. -- Highlights: ► PAA coated γ-Fe{sub 2}O{sub 3} nanoparticles were injected intravenously into healthy mice. ► We examine the distribution and physiological effects of

  9. Design of mucoadhesive polymeric films based on blends of poly(acrylic acid) and (hydroxypropyl)cellulose.

    PubMed

    Dubolazov, Artem V; Nurkeeva, Zauresh S; Mun, Grigoriy A; Khutoryanskiy, Vitaliy V

    2006-05-01

    Mixing of aqueous solutions of poly(acrylic acid) and (hydroxypropyl)cellulose results in formation of hydrogen-bonded interpolymer complexes, which precipitate and do not allow preparation of homogeneous polymeric films by casting. In the present work the effect of pH on the complexation between poly(acrylic acid) and (hydroxypropyl)cellulose in solutions and miscibility of these polymers in solid state has been studied. The pH-induced complexation-miscibility-immiscibility transitions in the polymer mixtures have been observed. The optimal conditions for preparation of homogeneous polymeric films based on blends of these polymers have been found, and the possibility of radiation cross-linking of these materials has been demonstrated. Although the gamma-radiation treatment of solid polymeric blends was found to be inefficient, successful cross-linking was achieved by addition of N,N'-methylenebis(acrylamide). The mucoadhesive potential of both soluble and cross-linked films toward porcine buccal mucosa is evaluated. Soluble films adhered to mucosal tissues undergo dissolution within 30-110 min depending on the polymer ratio in the blend. Cross-linked films are retained on the mucosal surface for 10-40 min and then detach.

  10. Chitosan-poly(acrylic acid) polyelectrolyte complex membranes: preparation, characterization and permeability studies.

    PubMed

    de Oliveira, H C L; Fonseca, J L C; Pereira, M R

    2008-01-01

    Polyelectrolyte complex (PEC) membranes were obtained by mixing solutions of two polymers of opposite charges, chitosan (Chi) and poly(acrylic acid) PAA. Three membranes were obtained: one made of pure chitosan and two membranes with chitosan mixed with PAA at a ratio of 95:5 (one prepared using PAA solution in 3.5% formic acid, named ChiPAA3.5, and another one using a PAA solution in 10% formic acid, named ChiPAA10). The membranes were characterized by swelling experiments, FT-IR spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), mechanical properties and permeability studies in relation to a drug model (sodium sulphamerazine). The calculation of degree of ionization showed that the lower the formic acid concentration was, the higher the PAA dissociation degree. Polyelectrolyte complex formation was characterized by FT-IR. Water uptake results showed that PEC membranes were more hydrophilic than pure chitosan, ChiPAA3.5 being the most. Morphological analysis by SEM and AFM showed that PAA addition changed the membranes morphology, especially for ChiPAA3.5. Mechanical properties indicated that PEC membranes were more rigid than pure chitosan membranes and that the morphology has an influence on tensile strength values. Permeability values decreased with complex formation and were lower for ChiPAA10 than ChiPAA3.5. However, as drug concentration was increased, the difference between the two complex membranes disappeared. The results were discussed considering the drug-membrane interactions. Diffusion coefficient values indicated that ChiPAA3.5 had a higher drug retention capacity than ChiPAA10.

  11. Low Light CMOS Contact Imager with an Integrated Poly-Acrylic Emission Filter for Fluorescence Detection

    PubMed Central

    Dattner, Yonathan; Yadid-Pecht, Orly

    2010-01-01

    This study presents the fabrication of a low cost poly-acrylic acid (PAA) based emission filter integrated with a low light CMOS contact imager for fluorescence detection. The process involves the use of PAA as an adhesive for the emission filter. The poly-acrylic solution was chosen due its optical transparent properties, adhesive properties, miscibility with polar protic solvents and most importantly its bio-compatibility with a biological environment. The emission filter, also known as an absorption filter, involves dissolving an absorbing specimen in a polar protic solvent and mixing it with the PAA to uniformly bond the absorbing specimen and harden the filter. The PAA is optically transparent in solid form and therefore does not contribute to the absorbance of light in the visible spectrum. Many combinations of absorbing specimen and polar protic solvents can be derived, yielding different filter characteristics in different parts of the spectrum. We report a specific combination as a first example of implementation of our technology. The filter reported has excitation in the green spectrum and emission in the red spectrum, utilizing the increased quantum efficiency of the photo sensitive sensor array. The thickness of the filter (20 μm) was chosen by calculating the desired SNR using Beer-Lambert’s law for liquids, Quantum Yield of the fluorophore and the Quantum Efficiency of the sensor array. The filters promising characteristics make it suitable for low light fluorescence detection. The filter was integrated with a fully functional low noise, low light CMOS contact imager and experimental results using fluorescence polystyrene micro-spheres are presented. PMID:22399920

  12. Low light CMOS contact imager with an integrated poly-acrylic emission filter for fluorescence detection.

    PubMed

    Dattner, Yonathan; Yadid-Pecht, Orly

    2010-01-01

    This study presents the fabrication of a low cost poly-acrylic acid (PAA) based emission filter integrated with a low light CMOS contact imager for fluorescence detection. The process involves the use of PAA as an adhesive for the emission filter. The poly-acrylic solution was chosen due its optical transparent properties, adhesive properties, miscibility with polar protic solvents and most importantly its bio-compatibility with a biological environment. The emission filter, also known as an absorption filter, involves dissolving an absorbing specimen in a polar protic solvent and mixing it with the PAA to uniformly bond the absorbing specimen and harden the filter. The PAA is optically transparent in solid form and therefore does not contribute to the absorbance of light in the visible spectrum. Many combinations of absorbing specimen and polar protic solvents can be derived, yielding different filter characteristics in different parts of the spectrum. We report a specific combination as a first example of implementation of our technology. The filter reported has excitation in the green spectrum and emission in the red spectrum, utilizing the increased quantum efficiency of the photo sensitive sensor array. The thickness of the filter (20 μm) was chosen by calculating the desired SNR using Beer-Lambert's law for liquids, Quantum Yield of the fluorophore and the Quantum Efficiency of the sensor array. The filters promising characteristics make it suitable for low light fluorescence detection. The filter was integrated with a fully functional low noise, low light CMOS contact imager and experimental results using fluorescence polystyrene micro-spheres are presented.

  13. Poly(acrylic acid)-directed synthesis of colloidally stable single domain magnetite nanoparticles via partial oxidation

    NASA Astrophysics Data System (ADS)

    Altan, Cem L.; Gurten, Berna; Sadza, Roel; Yenigul, Elcin; Sommerdijk, Nico A. J. M.; Bucak, Seyda

    2016-10-01

    Octahedral, single domain magnetite nanoparticles with average size of ~55 nm were synthesized through oxidative aging of a ferrous hydroxide (Fe(OH)2) precursor at high pH in water. The synthesis was also carried out in the presence of the hydrophilic polymer poly(acrylic acid). Presence of the polymer changed the particle morphology from octahedral to spherical while average size decreased to 40-50 nm. Although these particles have a tendency to precipitate due to their high magnetic moment, dispersions of these particles were obtained in the presence of this particular polymer which made the particles stable in water for several days making them suitable for various biotechnological applications such as cell separation owing to their low toxicity.

  14. Adsorption of low-molecular-weight sodium polyacrylate on hydroxyapatite.

    PubMed

    Misra, D N

    1993-10-01

    Adsorption of low-molecular-weight sodium polyacrylate from aqueous solution onto synthetic hydroxyapatite was studied at room temperature so that the mechanism of adhesion of polyacrylate cements to tooth mineral could be elucidated. The adsorption isotherm of sodium polyacrylate was Langmuirian in shape and was thus qualitatively different from that of polyacrylic acid (Misra, 1991), which exhibited an adsorption maximum. The self-association of the molecules that probably causes the maximum to occur with polyacrylic acid was effectively absent for the relatively well-ionized, electrostatically repelling polyacrylate ions of the salt. With the adsorption of acrylate ions, the concentration of phosphate ions increased monotonically, while the concentration of calcium ions showed a minimum. The adsorption of sodium polyacrylate was irreversible, as it was for polyacrylic acid.

  15. Assessment of the deoxyribonucleic acid damage caused by occupational exposure to chemical compounds in Isfahan Polyacryl Company

    PubMed Central

    Etebari, Mahmoud; Jafarian-Dehkordi, Abbas; Kahookar, Ahmad; Moradi, Shahla

    2014-01-01

    Background: Chemical pollutants found in industrial environments can cause chronic genotoxicity in vulnerable individuals during the long-term exposure. The primary purpose of the present study was to assess the deoxyribonucleic acid (DNA) damage caused by occupational exposure to industrial chemicals and secondary purpose is to investigate the effect of possible risk factors of genotoxicity. Materials and Methods: The blood samples of the workers of Isfahan Polyacryl Company were evaluated in terms of genotoxicity using the comet assay method. The percentage of DNA in the tail and tail moment were measured and DNA damage was evaluated. Furthermore, the effect of age, smoking, duration of working in the company and working in two parts of the company on the degree of vulnerability to genotoxicity was assessed. Results: The amount of DNA damage in the target group (the production line workers) was significantly higher than the control group (the staffs), 3.87 versus 1.52 as tail moment, (P < 0.0001). DNA damage was significantly higher in smoker groups compared with non-smoker target group and control group, 4.18 versus 3.07 and 1.52 respectively as tail moment, (P < 0.0001). Furthermore, it was higher in person working in two different parts of the company compared to those work in one part and control group, 4.63 versus 3.74 and 1.52 respectively as tail moment, (P < 0.0001). Conclusion: Occupational exposure to Polyacryl caused DNA damage. Smoking and working in two parts of the company may have a significant role in DNA damage. PMID:25197297

  16. Assessment of the deoxyribonucleic acid damage caused by occupational exposure to chemical compounds in Isfahan Polyacryl Company.

    PubMed

    Etebari, Mahmoud; Jafarian-Dehkordi, Abbas; Kahookar, Ahmad; Moradi, Shahla

    2014-06-01

    Chemical pollutants found in industrial environments can cause chronic genotoxicity in vulnerable individuals during the long-term exposure. The primary purpose of the present study was to assess the deoxyribonucleic acid (DNA) damage caused by occupational exposure to industrial chemicals and secondary purpose is to investigate the effect of possible risk factors of genotoxicity. The blood samples of the workers of Isfahan Polyacryl Company were evaluated in terms of genotoxicity using the comet assay method. The percentage of DNA in the tail and tail moment were measured and DNA damage was evaluated. Furthermore, the effect of age, smoking, duration of working in the company and working in two parts of the company on the degree of vulnerability to genotoxicity was assessed. The amount of DNA damage in the target group (the production line workers) was significantly higher than the control group (the staffs), 3.87 versus 1.52 as tail moment, (P < 0.0001). DNA damage was significantly higher in smoker groups compared with non-smoker target group and control group, 4.18 versus 3.07 and 1.52 respectively as tail moment, (P < 0.0001). Furthermore, it was higher in person working in two different parts of the company compared to those work in one part and control group, 4.63 versus 3.74 and 1.52 respectively as tail moment, (P < 0.0001). Occupational exposure to Polyacryl caused DNA damage. Smoking and working in two parts of the company may have a significant role in DNA damage.

  17. Mesoporous polyacrylic acid supported silver nanoparticles as an efficient catalyst for reductive coupling of nitrobenzenes and alcohols using glycerol as hydrogen source.

    PubMed

    Mandi, Usha; Roy, Anupam Singha; Kundu, Sudipta K; Roy, Susmita; Bhaumik, Asim; Islam, Sk Manirul

    2016-06-15

    Silver nanoparticle immobilized mesoporous cross-linked polyacrylic acid (Ag-MCP-1) has been synthesized via aqueous-phase polymerization of acrylic acid followed by the surface immobilization with silver nanoparticles. The nanocomposite material has been characterized by different spectroscopic techniques. Powder X-ray diffraction patterns revealed the formation of silver nanoparticles, while transmission electron microscope image showed that Ag nanoparticles are formed and uniformly dispersed in the mesoporous polyacrylic acid. The Ag-MCP-1 nanocomposite can be used as an efficient heterogeneous catalyst in the reductive coupling of nitrobenzenes and alcohols using glycerol as hydrogen source. This nanocomposite can be reused more than five times without any significant decrease in its catalytic activity.

  18. Electrospinning of Bioactive Dex-PAA Hydrogel Fibers

    NASA Astrophysics Data System (ADS)

    Louie, Katherine Boyook

    In this work, a novel method is developed for making nano- and micro-fibrous hydrogels capable of preventing the rejection of implanted materials. This is achieved by either (1) mimicking the native cellular environment, to exert fine control over the cellular response or (2) acting as a protective barrier, to camouflage the foreign nature of a material and evade recognition by the immune system. Comprehensive characterization and in vitro studies described here provide a foundation for developing substrates for use in clinical applications. Hydrogel dextran and poly(acrylic acid) (PAA) fibers are formed via electrospinning, in sizes ranging from nanometers to microns in diameter. While "as-electrospun" fibers are continuous in length, sonication is used to fragment fibers into short fiber "bristles" and generate nano- and micro- fibrous surface coatings over a wide range of topographies. Dex-PAA fibrous surfaces are chemically modified, and then optimized and characterized for non-fouling and ECM-mimetic properties. The non-fouling nature of fibers is verified, and cell culture studies show differential responses dependent upon chemical, topographical and mechanical properties. Dex-PAA fibers are advantageously unique in that (1) a fine degree of control is possible over three significant parameters critical for modifying cellular response: topography, chemistry and mechanical properties, over a range emulating that of native cellular environments, (2) the innate nature of the material is non-fouling, providing an inert background for adding back specific bioactive functionality, and (3) the fibers can be applied as a surface coating or comprise the scaffold itself. This is the first reported work of dex-PAA hydrogel fibers formed via electrospinning and thermal cross-linking, and unique to this method, no toxic solvents or cross-linking agents are needed to create hydrogels or for surface attachment. This is also the first reported work of using sonication to

  19. Molecular Dynamics Simulations of Adsorption of Poly(acrylic acid) and Poly(methacrylic acid) on Dodecyltrimethylammonium Chloride Micelle in Water: Effect of Charge Density.

    PubMed

    Sulatha, Muralidharan S; Natarajan, Upendra

    2015-09-24

    We have investigated the interaction of dodecyltrimethylammonium chloride (DoTA) micelle with weak polyelectrolytes, poly(acrylic acid) and poly(methacrylic acid). Anionic as well as un-ionized forms of the polyelectrolytes were studied. Polyelectrolyte-surfactant complexes were formed within 5-11 ns of the simulation time and were found to be stable. Association is driven purely by electrostatic interactions for anionic chains whereas dispersion interactions also play a dominant role in the case of un-ionized chains. Surfactant headgroup nitrogen atoms are in close contact with the carboxylic oxygens of the polyelectrolyte chain at a distance of 0.35 nm. In the complexes, the polyelectrolyte chains are adsorbed on to the hydrophilic micellar surface and do not penetrate into the hydrophobic core of the micelle. Polyacrylate chain shows higher affinity for complex formation with DoTA as compared to polymethacrylate chain. Anionic polyelectrolyte chains show higher interaction strength as compared to corresponding un-ionized chains. Anionic chains act as polymeric counterion in the complexes, resulting in the displacement of counterions (Na(+) and Cl(-)) into the bulk solution. Anionic chains show distinct shrinkage upon adsorption onto the micelle. Detailed information about the microscopic structure and binding characteristics of these complexes is in agreement with available experimental literature.

  20. Peroxyacetyl nitrate (PAN) and peroxyacetic acid (PAA) measurements by iodide chemical ionisation mass spectrometry: first analysis of results in the boreal forest and implications for the measurement of PAN fluxes

    NASA Astrophysics Data System (ADS)

    Phillips, G. J.; Pouvesle, N.; Thieser, J.; Schuster, G.; Axinte, R.; Fischer, H.; Williams, J.; Lelieveld, J.; Crowley, J. N.

    2013-02-01

    We describe measurements of peroxyacetyl nitrate (CH3C(O)O2NO2, PAN) and peroxyacetic acid (CH3C(O)OOH, PAA) in the Boreal forest using iodide chemical ionization mass spectrometry (ICIMS). The measurements were made during the Hyytiälä United Measurement of Photochemistry and Particles - Comprehensive Organic Particle and Environmental Chemistry (HUMPPA-COPEC-2010) measurement intensive. Mixing ratios of PAN and PAA were determined by measuring the acetate ion signal (CH3C(O)O-, m/z = 59) resulting from reaction of CH3C(O)O2 (from the thermal dissociation of PAN) or CH3C(O)OOH with iodide ions using alternatively heated and ambient temperature inlet lines. During some periods of high temperature (~ 30 °C) and low NOx (< 1 ppbv), PAA mixing ratios were similar to, or exceeded those of PAN and thus contributed a significant fraction of the total acetate signal. PAA is thus a potential interference for ICIMS measurements of PAN, and especially eddy covariance flux measurements in environments where the PAA flux is likely to be a significant proportion of the (short timescale) acetate ion variability. Within the range of mixing ratios of NOx measured during HUMPPA-COPEC, the modelled ratio of PAA-to-PAN was found to be sensitive to temperature (through the thermal decomposition rate of PAN) and the HO2 mixing ratio, thus providing some constraint to estimates of photochemical activity and oxidation rates in the Boreal environment.

  1. Peroxyacetyl nitrate (PAN) and peroxyacetic acid (PAA) measurements by iodide chemical ionisation mass spectrometry: first analysis of results in the boreal forest and implications for the measurement of PAN fluxes

    NASA Astrophysics Data System (ADS)

    Phillips, G. J.; Pouvesle, N.; Thieser, J.; Schuster, G.; Axinte, R.; Fischer, H.; Williams, J.; Lelieveld, J.; Crowley, J. N.

    2012-08-01

    We describe measurements of peroxyacetyl nitrate (CH3C(O)O2NO2, PAN) and peroxyacetic acid (CH3C(O)OOH, PAA) in the Boreal forest using iodide chemical ionization mass spectrometry (ICIMS). The measurements were made during the Hyytiälä United Measurement of Photochemistry and Particles - Comprehensive Organic Particle and Environmental Chemistry (HUMPPA-COPEC-2010) measurement intensive. Mixing ratios of PAN and PAA were determined by measuring the acetate ion signal (CH3C(O)O2-, m/z 59) resulting from reaction of CH3C(O)O2 (from the thermal dissociation of PAN) or CH3C(O)OOH with iodide ions using alternatively heated and ambient temperature inlet lines. During conditions of high temperature and low NOx, PAA mixing ratios were similar to, or exceeded those of PAN and thus contributed a significant fraction of the total acetate signal. PAA is thus a potential interference for ICIMS measurements of PAN, and especially eddy covariance flux measurements in environments where the PAA flux is likely to be a significant proportion of the short timescale acetate ion variability. Within the range of mixing ratios of NOx measured during HUMPPA-COPEC, the ratio of PAA-to-PAN was found to be sensitive to temperature (through the thermal decomposition rate of PAN) and the HO2 mixing ratio, thus providing some constraint to estimates of photochemical activity and oxidation rates in the Boreal environment.

  2. Simultaneous removal of atrazine and copper using polyacrylic acid-functionalized magnetic ordered mesoporous carbon from water: adsorption mechanism

    NASA Astrophysics Data System (ADS)

    Zhou, Yaoyu; Zhang, Fengfeng; Tang, Lin; Zhang, Jiachao; Zeng, Guangming; Luo, Lin; Liu, Yuanyuan; Wang, Pei; Peng, Bo; Liu, Xiaocheng

    2017-03-01

    Highly efficient simultaneous removal of atrazine and Cu(II) was accomplished using synthesized polyacrylic acid-functionalized magnetic ordered mesoporous carbon (P-MMC) as compared to magnetic ordered mesoporous carbon (MMC) and ordered mesoporous carbon (OMC). The mutual effects and interactive mechanism of their adsorption onto P-MMC were investigated systematically by binary, preloading and thermodynamic adsorption procedures. In both binary and preloading systems, the adsorption of atrazine was inhibited to some extent by the presence of Cu(II) because of selective recognition and direct competition, but the presence of atrazine had negligible effect on Cu(II) desorption. With the coexistence of humic acid (0-20 mg L-1), both atrazine and Cu(II) sorption increased slightly in sole and binary systems. With the concentration of coexisting NaCl increasing from 0 to 100 mM, the adsorption capacity for Cu(II) slightly decreased, but as for atrazine adsorption, it decreased at first, and then increased slightly in sole and binary systems. P-MMC was applied to treat real environmental samples, and the sorption capacities for atrazine and Cu(II) in real samples were all more than 91.47% and 96.43% of those in lab ultrapure water, respectively. Finally, comprehensively considering the relatively good renewability and the superior behavior in the application to real water samples, P-MMC has potential in removal of atrazine, Cu(II) and possibly other persistent organic pollutants from wastewater.

  3. Simultaneous removal of atrazine and copper using polyacrylic acid-functionalized magnetic ordered mesoporous carbon from water: adsorption mechanism

    PubMed Central

    Zhou, Yaoyu; Zhang, Fengfeng; Tang, Lin; Zhang, Jiachao; Zeng, Guangming; Luo, Lin; Liu, Yuanyuan; Wang, Pei; Peng, Bo; Liu, Xiaocheng

    2017-01-01

    Highly efficient simultaneous removal of atrazine and Cu(II) was accomplished using synthesized polyacrylic acid-functionalized magnetic ordered mesoporous carbon (P-MMC) as compared to magnetic ordered mesoporous carbon (MMC) and ordered mesoporous carbon (OMC). The mutual effects and interactive mechanism of their adsorption onto P-MMC were investigated systematically by binary, preloading and thermodynamic adsorption procedures. In both binary and preloading systems, the adsorption of atrazine was inhibited to some extent by the presence of Cu(II) because of selective recognition and direct competition, but the presence of atrazine had negligible effect on Cu(II) desorption. With the coexistence of humic acid (0–20 mg L−1), both atrazine and Cu(II) sorption increased slightly in sole and binary systems. With the concentration of coexisting NaCl increasing from 0 to 100 mM, the adsorption capacity for Cu(II) slightly decreased, but as for atrazine adsorption, it decreased at first, and then increased slightly in sole and binary systems. P-MMC was applied to treat real environmental samples, and the sorption capacities for atrazine and Cu(II) in real samples were all more than 91.47% and 96.43% of those in lab ultrapure water, respectively. Finally, comprehensively considering the relatively good renewability and the superior behavior in the application to real water samples, P-MMC has potential in removal of atrazine, Cu(II) and possibly other persistent organic pollutants from wastewater. PMID:28252022

  4. Simultaneous removal of atrazine and copper using polyacrylic acid-functionalized magnetic ordered mesoporous carbon from water: adsorption mechanism.

    PubMed

    Zhou, Yaoyu; Zhang, Fengfeng; Tang, Lin; Zhang, Jiachao; Zeng, Guangming; Luo, Lin; Liu, Yuanyuan; Wang, Pei; Peng, Bo; Liu, Xiaocheng

    2017-03-02

    Highly efficient simultaneous removal of atrazine and Cu(II) was accomplished using synthesized polyacrylic acid-functionalized magnetic ordered mesoporous carbon (P-MMC) as compared to magnetic ordered mesoporous carbon (MMC) and ordered mesoporous carbon (OMC). The mutual effects and interactive mechanism of their adsorption onto P-MMC were investigated systematically by binary, preloading and thermodynamic adsorption procedures. In both binary and preloading systems, the adsorption of atrazine was inhibited to some extent by the presence of Cu(II) because of selective recognition and direct competition, but the presence of atrazine had negligible effect on Cu(II) desorption. With the coexistence of humic acid (0-20 mg L(-1)), both atrazine and Cu(II) sorption increased slightly in sole and binary systems. With the concentration of coexisting NaCl increasing from 0 to 100 mM, the adsorption capacity for Cu(II) slightly decreased, but as for atrazine adsorption, it decreased at first, and then increased slightly in sole and binary systems. P-MMC was applied to treat real environmental samples, and the sorption capacities for atrazine and Cu(II) in real samples were all more than 91.47% and 96.43% of those in lab ultrapure water, respectively. Finally, comprehensively considering the relatively good renewability and the superior behavior in the application to real water samples, P-MMC has potential in removal of atrazine, Cu(II) and possibly other persistent organic pollutants from wastewater.

  5. Covalently-layers of PVA and PAA and in situ formed Ag nanoparticles as versatile antimicrobial surfaces.

    PubMed

    Fragal, Vanessa H; Cellet, Thelma S P; Pereira, Guilherme M; Fragal, Elizângela H; Costa, Marco Antonio; Nakamura, Celso Vataru; Asefa, Tewodros; Rubira, Adley F; Silva, Rafael

    2016-10-01

    The in situ synthesis of silver nanoparticles (AgNPs) within covalently-modified poly(ethylene terephthalate) (PET) films possessing ultra-thin layer of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) is successfully demonstrated. The resulting polymeric films are shown to exhibit antimicrobial activities toward Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and fungus (Candida albicans). To make the films, first PET surfaces were subject to photo-oxidation and subsequent solid-state grafting to attach a PVA layer, followed by a PAA layer. To synthesize the AgNPs inside the films, the PVA and PAA-modified PET was soaked in AgNO3 solution and the polymeric film was modified with the Ag(+) ions via Ag(+)-carboxylate interaction, and then the Ag(+) ions-containing polymer film was subject to either photo-reduction or thermal reduction processes. The PVA and PAA thin layers attached by covalent bonds to the PET surface uniquely promoted not only the in situ synthesis but also the stabilization of AgNPs. The formation of the AgNPs was confirmed by UV-vis spectroscopy or by monitoring the surface plasmon resonance (SPR) peak associated with AgNPs. The resulting PVA and PAA ultrathin layers modified and AgNPs containing PET served as bactericide and fungicide, inhibiting the growth of bacteria and fungi on the surfaces. Given PET's versatility and common use in many commercial processes, the method can be used for producing plastic surfaces with versatile antimicrobial and antibacterial properties.

  6. Mesoporous iron oxide nanoparticles prepared by polyacrylic acid etching and their application in gene delivery to mesenchymal stem cells.

    PubMed

    Cao, Binrui; Qiu, Penghe; Mao, Chuanbin

    2013-09-01

    Novel monodisperse mesoporous iron oxide nanoparticles (m-IONPs) were synthesized by a postsynthesis etching approach and characterized by electron microscopy. In this approach, solid iron oxide nanoparticles (s-IONPs) were first prepared following a solvothermal method, and then etched anisotropically by polyacrylic acid to form the mesoporous nanostructures. MTT cytotoxicity assay demonstrated that the m-IONPs have good biocompatibility with mesenchymal stem cells (MSCs). Owing to their mesoporous structure and good biocompatibility, these monodisperse m-IONPs were used as a nonviral vector for the delivery of a gene of vascular endothelial growth factor (VEGF) tagged with a green fluorescence protein (GFP) into the hard-to-transfect stem cells. Successful gene delivery and transfection were verified by detecting the GFP fluorescence from MSCs using fluorescence microscopy. Our results illustrated that the m-IONPs synthesized in this work can serve as a potential nonviral carrier in gene therapy where stem cells should be first transfected and then implanted into disease sites for disease treatment. Copyright © 2013 Wiley Periodicals, Inc.

  7. Paclitaxel-Loaded β-Cyclodextrin-Modified Poly(Acrylic Acid) Nanoparticles through Multivalent Inclusion for Anticancer Therapy.

    PubMed

    Yuan, Shanmei; Chen, Jiao; Sheng, Jie; Hu, Yong; Jiang, Zhongying

    2016-03-01

    A nanoassembled drug delivery system for anticancer treatment, formed by the host-guest interactions between paclitaxel (PTX) and β-cyclodextrin (β-CD) modified poly(acrylic acid) (PCDAA), is successfully prepared. After such design, the aqueous solubility of PTX is greatly increased from 0.34 to 36.02 μg mL(-1), and the obtained PCDAA-PTX nanoparticles (PCDAA-PTX NPs) exhibit a sustained PTX release behavior in vitro. In vitro cytotoxicity finds that PCDAA-PTX NPs can accumulate significantly in tumor cells and remain the pharmacological activity of PTX. The in vivo real-time biodistribution of PCDAA-PTX NPs is investigated using near-infrared fluorescence imaging, indicating that the PCDAA-PTX NPs can effectively target to the tumor site by the enhanced permeability and retention effect in H22 tumor-bearing mice. Through in vivo antitumor examination, PCDAA-PTX NPs exhibit superior efficacy in impeding the tumor growth compared to the commercially available Taxol®. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Hysteretic memory in pH-response of water contact angle on poly(acrylic acid) brushes.

    PubMed

    Yadav, Vivek; Harkin, Adrienne V; Robertson, Megan L; Conrad, Jacinta C

    2016-04-21

    We investigated the pH-dependent response of flat polyacid brushes of varying length and dispersity in the extended brush regime. Our model system consisted of poly(acrylic acid) brushes, which change from hydrophobic and neutral at low pH to hydrophilic and negatively charged at high pH, synthesized on silicon substrates using a grafting-from approach at constant grafting density. We observed three trends in the pH-response: first, the dry brush thickness increased as the pH was increased for brushes above a critical length, and this effect was magnified as the dispersity increased; second, the water contact angle measured at low pH was larger for brushes of greater dispersity; and third, brushes of sufficient dispersity exhibited hysteretic memory behavior in the pH-dependence of the contact angle, in which the contact angle upon increasing and decreasing pH differed. As a consequence, the pKa of the brushes measured upon increasing pH was consistently higher than that measured upon decreasing pH. The observed pH response is consistent with proposed changes in the conformation and charge distribution of the polyelectrolyte brushes that depend on the direction of pH change and the dispersity of the brushes.

  9. Crystallization and preliminary X-ray diffraction studies of the transcriptional repressor PaaX, the main regulator of the phenylacetic acid degradation pathway in Escherichia coli W

    PubMed Central

    Rojas-Altuve, Alzoray; Carrasco-López, César; Hernández-Rocamora, Víctor M.; Sanz, Jesús M.; Hermoso, Juan A.

    2011-01-01

    PaaX is the main regulator of the phenylacetic acid aerobic degradation pathway in bacteria and acts as a transcriptional repressor in the absence of its inducer phenylacetyl-coenzyme A. The natural presence and the recent accumulation of a variety of highly toxic aromatic compounds owing to human pollution has created considerable interest in the study of degradation pathways in bacteria, the most important microorganisms capable of recycling these compounds, in order to design and apply novel bioremediation strategies. PaaX from Escherichia coli W was cloned, overexpressed, purified and crystallized using the sitting-drop vapour-diffusion method at 291 K. Crystals grew from a mixture of 0.9 M Li2SO4 and 0.5 M sodium citrate pH 5.8. These crystals, which belonged to the monoclinic space group C2 with unit-cell parameters a = 167.88, b = 106.23, c = 85.87 Å, β = 108.33°, allowed the collection of an X-ray data set to 2.3 Å resolution. PMID:22102047

  10. Crystallization and preliminary X-ray diffraction studies of the transcriptional repressor PaaX, the main regulator of the phenylacetic acid degradation pathway in Escherichia coli W.

    PubMed

    Rojas-Altuve, Alzoray; Carrasco-López, César; Hernández-Rocamora, Víctor M; Sanz, Jesús M; Hermoso, Juan A

    2011-10-01

    PaaX is the main regulator of the phenylacetic acid aerobic degradation pathway in bacteria and acts as a transcriptional repressor in the absence of its inducer phenylacetyl-coenzyme A. The natural presence and the recent accumulation of a variety of highly toxic aromatic compounds owing to human pollution has created considerable interest in the study of degradation pathways in bacteria, the most important microorganisms capable of recycling these compounds, in order to design and apply novel bioremediation strategies. PaaX from Escherichia coli W was cloned, overexpressed, purified and crystallized using the sitting-drop vapour-diffusion method at 291 K. Crystals grew from a mixture of 0.9 M Li(2)SO(4) and 0.5 M sodium citrate pH 5.8. These crystals, which belonged to the monoclinic space group C2 with unit-cell parameters a = 167.88, b = 106.23, c = 85.87 Å, β = 108.33°, allowed the collection of an X-ray data set to 2.3 Å resolution.

  11. Poly(acrylic acid)-block-poly(vinyl alcohol) anchored maghemite nanoparticles designed for multi-stimuli triggered drug release

    NASA Astrophysics Data System (ADS)

    Liu, Ji; Detrembleur, Christophe; Debuigne, Antoine; de Pauw-Gillet, Marie-Claire; Mornet, Stéphane; Vander Elst, Luce; Laurent, Sophie; Labrugère, Christine; Duguet, Etienne; Jérôme, Christine

    2013-11-01

    Original core/corona nanoparticles composed of a maghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug delivery system (DDS) application. This kind of DDS aims to combine the advantage of stimuli-responsive polymer coating, in order to regulate the drug release behaviours under different conditions and furthermore, improve the biocompatibility and in vivo circulation half-time of the maghemite nanoparticles. Drug loading capacity was evaluated with methylene blue (MB), a cationic model drug. The triggered release of MB was studied under various stimuli such as pH, ionic strength and temperature. Local heating generated under alternating magnetic field (AMF) application was studied, and remotely AMF-triggered release was also confirmed, while a mild heating-up of the release medium was observed. Furthermore, their potential application as magnetic resonance imaging (MRI) contrast agents was explored via relaxivity measurements and acquisition of T2-weighted images. Preliminary studies on the cytotoxicity against mouse fibroblast-like L929 cell line and also their cellular uptake within human melanoma MEL-5 cell line were carried out. In conclusion, this kind of stimuli-responsive nanoparticles appears to be promising carriers for delivering drugs to some tumour sites or into cellular compartments with an acidic environment.Original core/corona nanoparticles composed of a maghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug delivery system (DDS) application. This kind of DDS aims to combine the advantage of stimuli-responsive polymer coating, in order to regulate the drug release behaviours under different conditions and furthermore, improve the biocompatibility and in vivo circulation half-time of the maghemite nanoparticles. Drug loading capacity was evaluated with methylene

  12. Synthesis of radiation crosslinked poly(acrylic acid) in the presence of phenyltriethoxysilane

    NASA Astrophysics Data System (ADS)

    Hassan, Safia; Yasin, Tariq

    2014-04-01

    Acrylic acid based superabsorbent hydrogel was prepared using phenyltriethoxysilane (PTES) as polyfunctional monomer. Different amounts of PTES were incorporated in acrylic acid and irradiated at different doses upto maximum of 30 kGy. The crosslinked acrylic acid showed hydrogel properties and its swelling kinetics, gel fraction and equilibrium degree of swelling (EDS) were studied. It was found that the increased PTES concentration decreased the EDS of the hydrogels. Infrared spectroscopy confirmed the crosslinking reaction between the feed components and the existence of siloxane bond. Thermogravimetric analysis showed an increase in the stability of the hydrogels having high PTES content. The swelling of the hydrogel was affected by pH, ionic strength and temperature. These hydrogels showed low swelling in acidic and basic pH range and high swelling around neutral pH. This switchable pH response of these hydrogels can be exploited in environmental and biomedical applications.

  13. The Influence of Polymer Topology on Pharmacokinetics: Differences Between Cyclic and Linear PEGylated Poly(acrylic Acid) Comb Polymers

    PubMed Central

    Chen, Bo; Jerger, Katherine; Fréchet, Jean M. J.; Szoka, Francis C.

    2009-01-01

    Water-soluble polymers for the delivery of chemotherapeutic drugs passively target solid tumors as a consequence of reduced renal clearance and the enhanced permeation and retention (EPR) effect. Elimination of the polymers in the kidney occurs due to filtration through biological nanopores with a hydrodynamic diameter comparable to the polymer. Therefore we have investigated chemical features that may broadly be grouped as “molecular architecture” such as: molecular weight, chain flexibility, number of chain ends and branching, to learn how they impact polymer elimination. In this report we describe the synthesis of four pairs of similar molecular weight cyclic and linear polyacrylic acid polymers grafted with polyethylene glycol (23, 32, 65, 114 kDa) with low polydispersities using ATRP and “click” chemistry. The polymers were radiolabeled with 125I and their pharmacokinetics and tissue distribution after intravenous injection were determined in normal and C26 adenocarcinoma tumored BALB/c mice. Cyclic polymers above the renal threshold of 30kDa had a significantly longer elimination time (between 10 to 33 % longer) than did the comparable linear polymer (for the 66 kDa cyclic polymer, t1/2, β= 35 ± 2 h) and a greater area under the serum concentration time curve. This resulted in a greater tumor accumulation of the cyclic polymer than the linear polymer counterpart. Thus water-soluble cyclic comb polymers join a growing list of polymer topologies that show greatly extended circulation times compared to their linear counterparts and provide alternative polymer architecture for use as drug carriers. PMID:19465070

  14. The influence of polymer topology on pharmacokinetics: differences between cyclic and linear PEGylated poly(acrylic acid) comb polymers.

    PubMed

    Chen, Bo; Jerger, Katherine; Fréchet, Jean M J; Szoka, Francis C

    2009-12-16

    Water-soluble polymers for the delivery of chemotherapeutic drugs passively target solid tumors as a consequence of reduced renal clearance and the enhanced permeation and retention (EPR) effect. Elimination of the polymers in the kidney occurs due to filtration through biological nanopores with a hydrodynamic diameter comparable to the polymer. Therefore we have investigated chemical features that may broadly be grouped as "molecular architecture" such as: molecular weight, chain flexibility, number of chain ends and branching, to learn how they impact polymer elimination. In this report we describe the synthesis of four pairs of similar molecular weight cyclic and linear polyacrylic acid polymers grafted with polyethylene glycol (23, 32, 65, 114 kDa) with low polydispersities using ATRP and "click" chemistry. The polymers were radiolabeled with (125)I and their pharmacokinetics and tissue distribution after intravenous injection were determined in normal and C26 adenocarcinoma tumored BALB/c mice. Cyclic polymers above the renal threshold of 30 kDa had a significantly longer elimination time (between 10 and 33% longer) than did the comparable linear polymer (for the 66 kDa cyclic polymer, t(1/2,beta)=35+/-2 h) and a greater area under the serum concentration versus time curve. This resulted in a greater tumor accumulation of the cyclic polymer than the linear polymer counterpart. Thus water-soluble cyclic comb polymers join a growing list of polymer topologies that show greatly extended circulation times compared to their linear counterparts and provide alternative polymer architecture for use as drug carriers.

  15. Specific influence of univalent cations on the ionization of alumina-coated TiO2 particles and on the adsorption of poly(acrylic)acid.

    PubMed

    Malgat, Alexandre; Boisvert, Jean-Philippe; Daneault, Claude

    2004-01-15

    A surface counterion titration method was used to monitor the interaction of monovalents cations (Li(+), Na(+), TMA(+)) with the surface of alumina-coated TiO(2) particles in concentrated media at different pH and electrolyte concentrations. This method allows measuring separately the negative and positive contribution to the surface charge. It showed that Cl(-) and TMA(+) are indifferent ions, but Li(+) and Na(+) specifically adsorb on the non-ionized alumina surface sites. The binding sequence of cations is Li(+)>Na(+)>TMA(+) at all ionic strengths investigated and is consistent with the structure-making and structure-breaking model developed a few decades ago. Polyacrylic acid (PAA) previously neutralized with the corresponding hydroxide (LiOH, NaOH, TMAOH) has been adsorbed on the alumina surface at different pH. The polymer counterion has a significant influence on the polymer adsorption. The sequence of the surface coverage as a function of the polymer counterion follows the order Li-PAA > Na-PAA > TMA-PAA. The much higher surface coverage with Li-PAA and Na-PAA compared to TMA-PAA is explained by the specific adsorption of Li-PAA and Na-PAA on the nonionized alumina surface sites, the same way LiCl and NaCl do.

  16. Grafting mechanism of electrochromic PAA-WO{sub 3} composite film

    SciTech Connect

    Choy, J.H.; Kim, Y.I.; Kim, B.W.; Campet, G.; Portier, J.; Huong, P.V.

    1999-02-01

    A micro-Raman spectroscopic study has been carried out to investigate the electrochromic process in a porous and nanocrystalline tungsten oxide film. The film was prepared by dipping the tin-doped indium oxide glass into an aqueous mixture solution of PAA (polyacrylic acid) and WO{sub 3}-NH{sub 4}OH. After heating at low temperature, around 100 C, the film was treated in 1 N HCl in order to achieve polycondensation, where the ammonium ion was replaced with a proton. In the micro-Raman spectra for the bleached and colored PAA-WO{sub 3} films, it was evident that the coloration accompanies a peak reduction at {approximately}960 cm{sup {minus}1} and a peak enhancement at {approximately}810 cm{sup {minus}1}. Based upon the present Raman observation, the authors can confirm that the electrochromism of the nanocrystalline tungsten oxide is dominated by the grafting process, i.e., the surface modification of {single_bond}W{sup VI}{double_bond}O bonds into {single_bond}W{sup V}{double_bond}O{sup (1{minus}{delta})+}{emdash}M{sup {delta}+} (M = H, Li) ones.

  17. The dynamics of sorption of sulfuric acid by weakly basic polyacrylic anion exchangers

    NASA Astrophysics Data System (ADS)

    Mamchenko, A. V.; Kushnir, T. V.

    2009-05-01

    The nonequilibrium dynamics of sorption of sulfuric acid by free base forms of Amberlite IRA-67 and Lewatite VP.OC.1072 weakly basic anion exchangers is studied. It is established that, in hydrodynamic regimes of filtration, which are typical of OH filters of the first stage of water-desalting plants, the limiting stage of sorption kinetics is inside diffusion. It is concluded that the process is correctly described by an asymptotic solution to the inside-diffusion model of sorption dynamics.

  18. Mineralisation of reconstituted collagen using polyvinylphosphonic acid/polyacrylic acid templating matrix protein analogues in the presence of calcium, phosphate and hydroxyl ions

    PubMed Central

    Kim, Young Kyung; Gu, Li-sha; Bryan, Thomas E.; Kim, Jong Ryul; Chen, Liang; Liu, Yan; Yoon, James C.; Breschi, Lorenzo; Pashley, David H.; Tay, Franklin R.

    2010-01-01

    The complex morphologies of mineralised collagen fibrils are regulated through interactions between the collagen matrix and non-collagenous extracellular proteins. In the present study, polyvinylphosphonic acid, a biomimetic analogue of matrix phosphoproteins, was synthesised and confirmed with FTIR and NMR. Biomimetic mineralisation of reconstituted collagen fibrils devoid of natural non-collagenous proteins was demonstrated with TEM using a Portland cement-containing resin composite and a phosphate-containing fluid in the presence of polyacrylic acid as sequestration, and polyvinylphosphonic acid as templating matrix protein analogues. In the presence of these dual biomimetic analogues in the mineralisation medium, intrafibrillar and extrafibrillar mineralisation via bottom-up nanoparticle assembly based on the nonclassical crystallisation pathway could be identified. Conversely, only large mineral spheres with no preferred association with collagen fibrils were observed in the absence of biomimetic analogues in the medium. Mineral phases were evident within the collagen fibrils as early as 4 hours after the initially-formed amorphous calcium phosphate nanoprecursors were transformed into apatite nanocrystals. Selected area electron diffraction patterns of highly mineralised collagen fibrils were nearly identical to those of natural bone, with apatite crystallites preferentially aligned along the collagen fibril axes. PMID:20621767

  19. Sensitive detection of dopamine via leucodopaminechrome on polyacrylic acid-coated ceria nanorods.

    PubMed

    Sheng, Weiqin; Zheng, Liang; Liu, Yan; Zhao, Xueqin; Weng, Jian; Zhang, Yang

    2017-09-08

    The major hurdle in detection of dopamine (DA) by electro-analysis is the presence of physiological interferents with a similar oxidation potential of DA. The conventional method is to enlarge the difference of their oxidation potentials. Here, we report an unconventional method to detect DA via leucodopaminechrome on CeO2 nanorods. Leucodopaminechrome is produced from the cyclization of dopamine-quinone, a product of two-electron oxidation of DA. Thus, its concentration is proportional to the DA concentration. Determining DA is demonstrated by measuring the reduction current of leucodopaminechrome on CeO2 nanorods. CeO2 nanorods demonstrate high electrocatalytic activity for reduction of leucodopaminechrome with a low potential at -0.27 V. The low detection potential of leucodopaminechrome can avoid the interference from ascorbic acid (AA) and uric acid (UA). Therefore, detecting DA via leucodopaminechrome is an effective method to avoid interference from AA and UA, and the suggested biosensor also displays good reproducibility and stability.

  20. Sensitive detection of dopamine via leucodopaminechrome on polyacrylic acid-coated ceria nanorods

    NASA Astrophysics Data System (ADS)

    Sheng, Weiqin; Zheng, Liang; Liu, Yan; Zhao, Xueqin; Weng, Jian; Zhang, Yang

    2017-09-01

    The major hurdle in detection of dopamine (DA) by electro-analysis is the presence of physiological interferents with a similar oxidation potential of DA. The conventional method is to enlarge the difference of their oxidation potentials. Here, we report an unconventional method to detect DA via leucodopaminechrome on CeO2 nanorods. Leucodopaminechrome is produced from the cyclization of dopamine-quinone, a product of two-electron oxidation of DA. Thus, its concentration is proportional to the DA concentration. Determining DA is demonstrated by measuring the reduction current of leucodopaminechrome on CeO2 nanorods. CeO2 nanorods demonstrate high electrocatalytic activity for reduction of leucodopaminechrome with a low potential at -0.27 V. The low detection potential of leucodopaminechrome can avoid the interference from ascorbic acid (AA) and uric acid (UA). Therefore, detecting DA via leucodopaminechrome is an effective method to avoid interference from AA and UA, and the suggested biosensor also displays good reproducibility and stability.

  1. The effect of methylcellulose on metronidazole release from polyacrylic acid hydrogels.

    PubMed

    Musial, Witold

    2007-08-01

    Topical treatment of acne rosacea, a chronic condition characterized by recurrent course for many years, is primarily based on metronidazole preparations. The aim of this study was to evaluate the effect of various acrylic acid polymers, in composition with methylcellulose on metronidazole release rate from hydrogels proposed for the treatment of acne rosacea. Viscosity and release studies using "Paddle over Disk" system with semipermeable membrane of MWCO 3500 were performed. Compositions of Carbopol 971P and methylcellulose revealed an increase in viscosity with increasing concentration of methylcellulose in the range of 17200-26166 mPa.s. In all the examined formulations, the release process was characterized by a two-stage course. Among bipolymeric formulations, the highest first-stage release rate of 9.18 x 10(-3) min(-1) was determined for the gel consisting of 2.00% Carbopol 980NF with 1.00% methylcellulose. The second-stage release rates ranged between 2.88 x 10(-3) and 8.00 x 10(-3) min(-1). Two-stage release course can thus be attributed to metronidazole distribution into two compartments of hydrogel matrix. Proposed gels, with similar rheological properties, may be used for ex vivo and in vivo studies to obtain a suitable drug activity of metronidazole in the treatment of acne rosacea.

  2. Osteochondral defect repair using a polyvinyl alcohol-polyacrylic acid (PVA-PAAc) hydrogel.

    PubMed

    Bichara, David A; Bodugoz-Sentruk, Hatice; Ling, Doris; Malchau, Erik; Bragdon, Charles R; Muratoglu, Orhun K

    2014-08-01

    Poly(vinyl alcohol) (PVA) hydrogels can be candidates for articular cartilage repair due to their high water content. We synthesized a PVA-poly(acrylic acid) (PAAc) hydrogel formulation and determined its ability to function as a treatment option for condylar osteochondral (OC) defects in a New Zealand white rabbit (NZWR) model for 12 weeks and 24 weeks. In addition to hydrogel OC implants, tensile bar-shaped hydrogels were also implanted subcutaneously to evaluate changes in mechanical properties as a function of in vivo duration. There were no statistically significant differences (p > 0.05) in the water content measured in the OC hydrogel implant that was harvested after 12 weeks and 24 weeks, and non-implanted controls. There were no statistically significant differences (p > 0.05) in the break stress, strain at break or modulus of the tensile bars either between groups. Histological analysis of the OC defect, synovial capsule and fibrous tissue around the tensile bars determined hydrogel biocompatibility. Twelve-week hydrogels were found to be in situ flush with the articular cartilage; meniscal tissue demonstrated an intact surface. Twenty-four week hydrogels protruded from the defect site due to lack of integration with subchondral tissue, causing fibrillation to the meniscal surface. Condylar micro-CT scans ruled out osteolysis and bone cysts of the subchondral bone, and no PVA-PAAc hydrogel contents were found in the synovial fluid. The PVA-PAAc hydrogel was determined to be fully biocompatible, maintained its properties over time, and performed well at the 12 week time point. Physical fixation of the PVA-PAAc hydrogel to the subchondral bone is required to ensure long-term performance of hydrogel plugs for OC defect repair.

  3. Adsorption of sodium polyacrylate in high solids loading calcium carbonate slurries.

    PubMed

    Taylor, Joshua J; Sigmund, Wolfgang M

    2010-01-15

    The adsorption of sodium polyacrylate (NaPAA) in slurries with up to 75 wt.% calcium carbonate was investigated with the use of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and adsorption of probe molecules. Analysis of the IR spectra demonstrated that the carboxylate groups of NaPAA adsorbed onto ground calcium carbonate (GCC) in three different modes. These modes were shown to be dependent on the solids loading and age of the slurry. Further investigation lead to the determination of the chelating ability of NaPAA at high solids loading.

  4. Thin film of Poly(acrylic acid-co-allyl acrylate) as a Sacrificial Protective Layer for Hydrophilic Self Cleaning Glass

    PubMed Central

    Lejnieks, Jānis; Mourran, Ahmed; Tillmann, Walter; Keul, Helmut; Möller, Martin

    2010-01-01

    Poly(acrylic acid-co-allyl acrylate) statistical copolymers were synthesized in a controlled manner in two steps: first tert.butyl acrylate and allyl acrylate were polymerized via atom transfer radical polymerization (ATRP) and afterwords the tert.butyl protective groups were removed via hydrolysis. Samples of self cleaning glass (SCG) were coated with thin films of poly(acrylic acid-co-allyl acrylate) and cross-linked afterwards by UV irradiation (in the presence of a photoinitiator and an accelerator). Solution cast thin films were transparent and homogeneous before and after UV cross-linking. The irradiated samples were found to be hydrophilic (Θ < 20°) and water insoluble. The coating prevented the spontaneous hydrophobization of the SCG by residual silicon exhaled from the sealing material. The TiO2 photocatalyst that covers the glass surface was found to strip the protective coating. The rate of the photooxidation process was measured by IR spectroscopy. The real field performance of the protective coating was also tested.

  5. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified as 2-propenoic acid, polymers with N,N-di-2-propenyl-2-propen-1-amine and hydrolyzed polyvinyl acetate, sodium salts, graft (CAS Reg. No. 166164-74-5); or (2) 2-propenoic acid, polymer with 2-ethyl-2-(((1-oxo...

  6. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified as 2-propenoic acid, polymers with N,N-di-2-propenyl-2-propen-1-amine and hydrolyzed polyvinyl acetate, sodium salts, graft (CAS Reg. No. 166164-74-5); or (2) 2-propenoic acid, polymer with 2-ethyl-2-(((1-oxo...

  7. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified as 2-propenoic acid, polymers with N,N-di-2-propenyl-2-propen-1-amine and hydrolyzed polyvinyl acetate, sodium salts, graft (CAS Reg. No. 166164-74-5); or (2) 2-propenoic acid, polymer with 2-ethyl-2-(((1-oxo...

  8. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified as 2-propenoic acid, polymers with N,N-di-2-propenyl-2-propen-1-amine and hydrolyzed polyvinyl acetate, sodium salts, graft (CAS Reg. No. 166164-74-5); or (2) 2-propenoic acid, polymer with 2-ethyl-2-(((1-oxo...

  9. Separation of poly(acrylic acid) salts according to topology using capillary electrophoresis in the critical conditions.

    PubMed

    Maniego, Alison R; Ang, Dale; Guillaneuf, Yohann; Lefay, Catherine; Gigmes, Didier; Aldrich-Wright, Janice R; Gaborieau, Marianne; Castignolles, Patrice

    2013-11-01

    Branching was detected in polyacrylates synthesised through radical polymerization via solution-state NMR, while inconsistencies have been reported for the determination of the molar mass of hydrophilic polyacrylates using aqueous-phase and organic-phase size-exclusion chromatography. In this work, poly(sodium acrylate)s, PNaAs, of various topologies were separated for the first time using free-solution capillary electrophoresis (CE). Free-solution CE does not separate the PNaAs by their molar mass, similarly to separations by liquid chromatography in the critical conditions, rather by different topologies (linear, star branched, and hyperbranched). The electrophoretic mobility of PNaAs increases as the degree of branching decreases. Separation is shown to be not only by the topology but also by the end groups as expected for a separation in the critical conditions: replacing a relatively bulky nitroxide end group with hydrogen atom yielded a higher electrophoretic mobility. This novel method, capillary electrophoresis in the critical conditions enabled, for the first time, the separation of hydrophilic polyacrylates according to their topology (branching) and their chain ends. This will allow meaningful and accurate characterization of their branched topologies as well as molar masses and progress in for advanced applications such as drug delivery or flocculation.

  10. Design and development of pH-responsive HSPC:C12H25-PAA chimeric liposomes.

    PubMed

    Naziris, Nikolaos; Pippa, Natassa; Meristoudi, Anastasia; Pispas, Stergios; Demetzos, Costas

    2017-06-01

    The application of stimuli-responsive medical practices has emerged, in which pH-sensitive liposomes figure prominently. This study investigates the impact of the incorporation of different amounts of pH-sensitive polymer, C12H25-PAA (poly(acrylic acid) with a hydrophobic end group) in l-α-phosphatidylcholine, hydrogenated (Soy) (HSPC) phospholipidic bilayers, with respect to biomimicry and functionality. PAA is a poly(carboxylic acid) molecule, classified as a pH-sensitive polymer, whose pH-sensitivity is attributed to its regulative -COOH groups, which are protonated under acidic pH (pKa ∼4.2). Our concern was to fully characterize, in a biophysical and thermodynamical manner, the mixed nanoassemblies arising from the combination of the two biomaterials. At first, we quantified the physicochemical characteristics and physical stability of the prepared chimeric nanosystems. Then, we studied their thermotropic behavior, through measurement of thermodynamical parameters, using Differential Scanning Calorimetry (DSC). Finally, the loading and release of indomethacin (IND) were evaluated, as well as the physicochemical properties and stability of the nanocarriers incorporating it. As expected, thermodynamical findings are in line with physicochemical results and also explain the loading and release profiles of IND. The novelty of this investigation is the utilization of these pH-sensitive chimeric advanced Drug Delivery nano Systems (aDDnSs) in targeted drug delivery which relies entirely on the biophysics and thermodynamics between such designs and the physiological membranes and environment of living organisms.

  11. Polyacrylate adsorbents for the selective adsorption of cholesterol-rich lipoproteins from plasma or blood

    PubMed Central

    Heuck, Claus-Chr.

    2011-01-01

    Polyacrylate (PAA) adsorbents selectively bind low density lipoproteins (LDL) from human plasma and blood, whereas very low density lipoproteins (VLDL) are only minimally adsorbed. The adsorption of cholesterol-rich lipoproteins to PAA adsorbents is related to the molecular weight (mw) of the polyanion ligand. Ca++ and Mg++ inhibit the binding of LDL to PAA adsorbents. The chemical composition of the organic hardgels of the adsorbents does not have an influence on adsorption. The selective adsorption of LDL to PAA adsorbents can be explained to result from their low negative surface charge density and the specific colloid-chemical properties of the surface-bound PAA, which do not prevent LDL from binding to charge-like domains of the ligand. By contrast, VLDL and high density lipoproteins (HDL) are repelled from the adsorbents due to their higher negative surface charge density. PMID:21289994

  12. Polyacrylate adsorbents for the selective adsorption of cholesterol-rich lipoproteins from plasma or blood.

    PubMed

    Heuck, Claus-Chr

    2011-01-24

    Polyacrylate (PAA) adsorbents selectively bind low density lipoproteins (LDL) from human plasma and blood, whereas very low density lipoproteins (VLDL) are only minimally adsorbed. The adsorption of cholesterol-rich lipoproteins to PAA adsorbents is related to the molecular weight (mw) of the polyanion ligand. Ca(++) and Mg(++) inhibit the binding of LDL to PAA adsorbents. The chemical composition of the organic hardgels of the adsorbents does not have an influence on adsorption. The selective adsorption of LDL to PAA adsorbents can be explained to result from their low negative surface charge density and the specific colloid-chemical properties of the surface-bound PAA, which do not prevent LDL from binding to charge-like domains of the ligand. By contrast, VLDL and high density lipoproteins (HDL) are repelled from the adsorbents due to their higher negative surface charge density.

  13. FT-IR and FT-Raman studies of cross-linking processes with Ca²⁺ ions, glutaraldehyde and microwave radiation for polymer composition of poly(acrylic acid)/sodium salt of carboxymethyl starch - In moulding sands, Part II.

    PubMed

    Grabowska, Beata; Sitarz, Maciej; Olejnik, Ewa; Kaczmarska, Karolina; Tyliszczak, Bozena

    2015-12-05

    The hardening process of moulding sands on quartz matrices bound by polymer binders containing carboxyl and hydroxyl groups can be carried out by using physical (microwave radiation, thermal holding) and chemical (Ca(2+) cations, glutaraldehyde) cross-linking agents. The highest hardening level obtain moulding sand samples containing binders in a form of the aqueous composition of poly(acrylic acid)/sodium salt of carboxymethyl starch (PAA/CMS-Na) within the microwave radiation field, for which the bending strength is of 1.6 MPa value even after 24h from ending the agent activity. The authors focused, in this study, on finding the reason of this effect. It was shown, by means of the FT-IR and FT-Raman spectroscopic methods, that the chemical adsorption process activated by microwaves plays an essential role. The applied microwaves activate the polar groups present in the polymer composition structure as well as the quartz crystals surfaces (silane groups). Then the chemical adsorption occurs in the binder-matrix system within the microwave radiation field and intermolecular lattices are formed with a participation of hydrogen bridges (SiOH⋯OC, SiOH⋯OH) and COSi type bonds.

  14. Vesicles prepared with the complex salts dioctadecyldimethylammonium polyacrylates.

    PubMed

    Alves, Fernanda Rosa; Loh, Watson

    2012-02-15

    The effect of a polymeric counterion on the thermotropic behavior of sonicated vesicles formed by complex salts in aqueous solution and with decanol (C(10)OH) and tetradecanol (C(14)OH) was investigated. The complex salts were prepared with dioctadecyldimethylammonium bromide (DODAB) and polyacrylic acids (PAA, containing 30 or 6000 repeating units), being referred to as DODAPA(30) and DODAPA(6000). Vesicles containing polymeric counterions presented higher contents of multilamellar vesicles that were dependent on the complex salt concentration and on the counterion chain length. For comparison, studies were performed with DODAAc, with the counterion acetate, resulting in the formation of mostly unilamellar vesicles, as expected due greater dissociation, leading to greater electrical repulsion between bilayers. Mixtures of these complex salts and DODAX (where X=acetate or bromide) were also investigated with respect to their vesicles thermotropic behavior and size. This study opens the possibility of applying the methodology of direct complex salt preparation (as opposed to mixing the surfactant and polymeric components) to produce vesicles with controlled composition and properties. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Simultaneous Enhancement of Bioactivity and Stability of Laccase by Cu(2+)/PAA/PPEGA Matrix for Efficient Biosensing and Recyclable Decontamination of Pyrocatechol.

    PubMed

    Chen, Tao; Xu, Yuanhong; Peng, Zhi; Li, Aihua; Liu, Jingquan

    2017-02-07

    Simultaneously enhancing the catalytic bioactivity and stability of enzyme is still an intractable issue in the enzymatic study. Herein, a facile and effective approach was designed to immobilize and modify laccase on a Cu(2+)-adsorbed pyrene-terminated block copolymer [poly(acrylic acid)/poly(poly(ethylene glycol) acrylate)] (PAA/PPEGA), which was prepared via well-controlled reversible addition-fragmentation chain transfer polymerization. PAA provided the supporting matrix for firm immobilization of Cu(2+), an enzyme bioactivity inducer, onto the microstructure of laccase, while avoiding any contamination of the heavy metal Cu(2+) into the following application system. The water-soluble, biocompatible, and nontoxic PPEGA was used as an ideal modifier to improve the laccase stability. Accordingly, the modified laccase exhibited enhanced catalytic bioactivity and stability simultaneously to 447% and 237%, respectively. The modified laccase was immobilized on the highly oriented pyrolytic graphite surface and large-area graphene papers through π-π stacking interactions between the pyrene moiety of PAA/PPEGA and the π-conjugated graphenelike surface. The as-prepared portable solid-state electrochemical laccase biosensor showed lowest detection limit of 50 nM (S/N ≥ 3) and long-term stability for pyrocatechol detection. Besides, the laccase immobilization on graphene paper provided efficient pyrocatechol decontamination platform with convenience and recyclability, which could retain the laccase bioactivity of 176% after 8 consecutive operations.

  16. Optimalization of Freezing-Thawing Process in Enhancing Magnetic Properties of Fe3O4/PAA/PVA Magnetic Hydrogel Composites

    NASA Astrophysics Data System (ADS)

    Sunaryono; Hifdziyah, H.; Taufiq, A.; Diantoro, M.; Mufti, N.

    2017-05-01

    Magnetic hydrogel composites of Fe3O4/polyacrylic acid (PAA)/polyvinyl alcohol (PVA) have been successfully fabricated through a freezing-thawing cycle method. The natural iron sand-based Fe3O4 filler nanoparticle has been successfully synthesized through coprecipitation at a room temperature. The crystal structure and the morphology of the Fe3O4 nanoparticle were investigated by using X-ray Diffractometer (XRD), and Transmission Electron Microscopy (TEM), respectively. The study of magnetic characteristics of the Fe3O4/PAA/PVA magnetic hydrogel composites were characterized by using Vibrating Sample Magnetometer (VSM). Based on the quantitative analysis, the morphology of Fe3O4 filler characterized by using TEM has a particle size around of 8 nm. This result was well confirmed with the analysis of the XRD and VSM data. Additionally, the study of the magnetic properties of the Fe3O4/PAA/PVA magnetic hydrogel composites decreased saturation magnetization significantly with the increase of the number of freezing-thawing cycles. This result indicated that the distribution pattern of the Fe3O4 filler in the magnetic hydrogel composites was more optimal when the process of freezing-thawing reached seven times cycles.

  17. Disinfection efficiency of peracetic acid (PAA): inactivation of coliphages and bacterial indicators in a municipal wastewater plant.

    PubMed

    Zanetti, F; De Luca, G; Sacchetti, R; Stampi, S

    2007-11-01

    The aim of the study was to assess the efficiency of low doses of peracetic acid against viral and bacterial indicators in wastewater and to evaluate if the treatment allows regulatory requirements to be satisfied. A total of 31 samplings were carried out, each involving the collection of secondary effluent and of effluent disinfected with 1.2 or 1.5 mg l(-1) of peracetic acid (contact time 20 minutes). In each sample were measured: somatic coliphages, F-specific RNA bacteriophages, Escherichia coli, total and faecal coliforms, enterococci. Peracetic acid disinfection showed significant differences between the reductions of the microorganisms tested: E. coli showed the highest reduction (1.78 and 2.43 Log respectively with 1.2 and 1.5 mg l(-1) of peracetic acid) and phages the lowest (ranging between 0.52 and 0.60 Log). Only a concentration of 1.5 mg l(-1) of peracetic acid would enable the effluent to be discharged into surface waters in compliance with Italian regulations. The variability of microbial resistance against the peracetic acid disinfection treatment, underlines the importance of assessing disinfection efficiency by using more than one indicator microorganism. The detection of E. coli could be usefully accompanied by tests for more resistant microorganisms such as enterococci or coliphages. In conclusion, peracetic acid can be used for the disinfection of effluents even at low doses, with the advantage of reducing costs and preventing the formation of significant amounts of genotoxic by-products.

  18. Influence of mineral on the load deformation behavior of polymer in hydroxyapatite-polyacrylic acid nanocomposite biomaterials: a steered molecular dynamics study.

    PubMed

    Bhowmik, Rahul; Katti, Kalpana S; Katti, Dinesh R

    2008-04-01

    Composites of hydroxyapatite and polymers are widely studied for bone replacement. To perform satisfactorily in the human body, these composites need to be biocompatible and exhibit optimum mechanical properties. The load-deformation behavior of composites is often investigated using experimental techniques. However, the molecular mechanisms of load deformation behavior are not clearly understood. We have used Steered Molecular Dynamics to evaluate the load-deformation behavior at interfaces in polyacrylic acid-hydroxyapatite (HAP) composite models. The polymer is pulled at constant velocity in close proximity of HAP. On comparing the results obtained for deformation behavior of polymer in vicinity of mineral and in the absence of mineral, it was found that energy required to pull the polymer in close proximity of HAP is significantly higher. Also, structural details of the load transfer mechanisms in composite were investigated under both conditions. Our simulations indicate that there is a significant role of mineral-polymer interactions on the mechanical response of polymer.

  19. High cycling stability of anodes for lithium-ion batteries based on Fe3O4 nanoparticles and poly(acrylic acid) binder

    NASA Astrophysics Data System (ADS)

    Maroni, F.; Gabrielli, S.; Palmieri, A.; Marcantoni, E.; Croce, F.; Nobili, F.

    2016-11-01

    Fe3O4 nanoparticles synthesized by a base catalyzed method are tested as anode material for Li-ion batteries. The pristine nanoparticles are morphologically characterized showing an average size of 11 nm. Electrodes are prepared using high-molecular weight Poly (acrylic acid) as improved binder and ethanol as low cost and environmentally friendly solvent. The evaluation of electrochemical properties shows high specific capacity values of 857 mA hg-1 after 200 cycles at a specific current of 462 mAg-1, as well as an excellent rate capability with specific current values up to 18480 mAg-1. To the best of our knowledge, this is the first report of Fe3O4 nanoparticles cycling with PAA as binder.

  20. Design of a novel crosslinked HEC-PAA porous hydrogel composite for dissolution rate and solubility enhancement of efavirenz.

    PubMed

    Mabrouk, M; Chejara, D R; Mulla, J A S; Badhe, R V; Choonara, Y E; Kumar, P; du Toit, L C; Pillay, V

    2015-07-25

    The purpose of this research was to synthesize, characterize and evaluate a Crosslinked Hydrogel Composite (CHC) as a new carrier for improving the solubility of the anti-HIV drug, efavirenz. The CHC was prepared by physical blending of hydroxyethylcellulose (HEC) with poly(acrylic acid) (PAA) (1:1) in the presence of poly(vinyl alcohol) (PVA) (as a crosslinker) (1:5) under lyophilization. Efavirenz was loaded in situ into the CHC in varying proportions (200-600 mg). The CHC demonstrated impressive rheological properties (dynamic viscosity=6053 mPa; 500 s(-1)) and tensile strength (2.5 mPa) compared with the native polymers (HEC and PAA). The physicochemical and thermal behavior also confirmed that the CHC was compatible with efavirenz. The incorporation of efavirenz in the CHC increased the surface area (4.4489-8.4948 m(2)/g) and pore volume (469.547-776.916Å) of the hydrogel system which was confirmed by SEM imagery and BET surface area measurements. The solubility of efavirenz was significantly enhanced (150 times) in a sustained release manner over 24h as affirmed by the in vitro drug release studies. The hydration medium provided by the CHC network played a pivotal role in improving the efavirenz solubility via increasing hydrogen bonding as proved by the zeta potential measurements (-18.0 to +0.10). The CHC may be a promising alternative as an oral formulation for the delivery of efavirenz with enhanced solubility.

  1. Intelligent core-shell nanoparticles and hollow spheres based on gelatin and PAA via template polymerization.

    PubMed

    Wang, Yansong; Zhang, Youwei; Du, Weiping; Wu, Chengxun; Zhao, Jiongxin

    2009-06-15

    PAA/gelatin nanoparticles, with interpolymer complexes of gelatin and polyacrylic acid (PAA) as the cores and gelatin as the shells, were prepared via facile polymerization of AA on gelatin template. The morphology change of the nanoparticles during the reaction was traced by a combined use of dynamic light scattering (DLS) and atomic force microscopy (AFM) techniques, which revealed a discrepancy among the structure of the nanoparticles formed at different stages of the reaction: as the reaction proceeds, nanoparticles with larger compact cores and thinner shells are produced. The resultant nanoparticles are multi-responsive. Especially, they exhibit a significant temperature-dependent size change: upon raising the temperature from 25 degrees C, the nanoparticle size decreases monotonically until reaching equilibrium at about 40 degrees C. This temperature-dependence of the nanoparticle size was found to be reversible provided the nanoparticle solution was cooled at a low temperature (4 degrees C). The thermo-sensitivity of the nanoparticles is attributed to the thermo-induced sol-gel transition of the gelatin shells. In addition, the nanoparticles were further converted to hollow spheres via successive locking the shell structure by the reaction of gelatin with cross-linker glutaraldehyde, and cavitation of the cross-linked nanoparticles by switching the medium from acidic to neutral. The cavitation process was monitored by DLS, which indicated a mass decrease and size shrinkage. AFM and transmission electron microscopy (TEM) were used to trace the morphology change of the nanoparticles during the cavitation. The hollow structure was confirmed by TEM observation.

  2. Thiolated polymers: self-crosslinking properties of thiolated 450 kDa poly(acrylic acid) and their influence on mucoadhesion.

    PubMed

    Marschütz, Michaela K; Bernkop-Schnürch, Andreas

    2002-05-01

    This study examined the rheological and mucoadhesive properties of a self-crosslinking anionic thiolated polymer in vitro. Mediated by a carbodiimide, L-cysteine was covalently bound to poly(acrylic acid) of 450 kDa molecular mass. The resulting thiolated polymers (conjugates I and II) contained 90.5+/-15.8 and 511.6+/-52 micromol thiol groups per gram polymer, respectively (mean+/-S.D., n=3). The amount of covalently attached cysteine was therefore dependent on the concentration of carbodiimide used for the coupling reaction. Both conjugates (3%, m/v) were capable of forming inter- and/or intramolecular disulfide bonds in 100 mM phosphate buffer pH 6.8. Consequently, the apparent viscosity of conjugates I and II increased 12- and 10-fold, respectively, within 24 h of incubation at 37 degrees C. Further, rheological synergy was observed by mixing equal volumes of polymer (unmodified as well as modified) with a mucin solution. A six-fold increase in viscosity immediately after mixing could be observed for the conjugate II/mucin mixture. This clearly indicates the high interaction potential of self-crosslinking thiomers with the mucus gel layer. Mucoadhesion studies confirmed the rheological results. Tablets based on conjugate II remained attached on freshly excised porcine mucosa for about 25 times longer than the corresponding controls, which is the longest time of mucoadhesion ever found among anionic thiomers. Due to the results of the present study, self-crosslinking thiolated poly(acrylates) of 450 kDa represent very promising excipients for the development of various mucoadhesive drug delivery systems.

  3. Physicochemical properties of pH-controlled polyion complex (PIC) micelles of poly(acrylic acid)-based double hydrophilic block copolymers and various polyamines.

    PubMed

    Warnant, J; Marcotte, N; Reboul, J; Layrac, G; Aqil, A; Jerôme, C; Lerner, D A; Gérardin, C

    2012-05-01

    The physicochemical properties of polyion complex (PIC) micelles were investigated in order to characterize the cores constituted of electrostatic complexes of two oppositely charged polyelectrolytes. The pH-sensitive micelles were obtained with double hydrophilic block copolymers containing a poly(acrylic acid) block linked to a modified poly(ethylene oxide) block and various polyamines (polylysine, linear and branched polyethyleneimine, polyvinylpyridine, and polyallylamine). The pH range of micellization in which both components are ionized was determined for each polyamine. The resulting PIC micelles were characterized using dynamic light scattering and small-angle X-ray scattering experiments (SAXS). The PIC micelles presented a core-corona nanostructure with variable polymer density contrasts between the core and the corona, as revealed by the analysis of the SAXS curves. It was shown that PIC micelle cores constituted by polyacrylate chains and polyamines were more or less dense depending on the nature of the polyamine. It was also determined that the density of the cores of the PIC micelles depended strongly on the nature of the polyamine. These homogeneous cores were surrounded by a large hairy corona of hydrated polyethylene oxide block chains. Auramine O (AO) was successfully entrapped in the PIC micelles, and its fluorescence properties were used to get more insight on the core properties. Fluorescence data confirmed that the cores of such micelles are quite compact and that their microviscosity depended on the nature of the polyamine. The results obtained on these core-shell micelles allow contemplating a wide range of applications in which the AO probe would be replaced by various cationic drugs or other similarly charged species to form drug nanocarriers or new functional nanodevices.

  4. Synthesis of hollow hybrid hydroxyapatite microspheres based on chitosan-poly(acrylic acid) microparticles.

    PubMed

    Zhang, Haibin; Zhou, Kechao; Li, Zhiyou; Huang, Suping

    2009-06-01

    Core-template-free hybrid hydroxyapatite (HA) hollow microspheres based on a chitosan-poly acrylic acid (CS-PAA) complex were prepared. The amine groups on chitosan can interact with the carboxyl groups of poly(acrylic acid) to form hollow microspheres. The hollow HA microspheres of about 1.0 microm are obtained by heterogeneous nucleation of HA on CS-PAA hollow spheres. Gelatin (Gel), acting as a novel cross-link agent, is introduced to bind the spheres of CS-PAA and HA. The forming mechanism of hollow spheres and the influencing factors on the size of microspheres are investigated. In addition, the role of Gel is elucidated in the forming process of the hollow hybrid sphere.

  5. Frequency-dependent magnetic susceptibility of magnetite and cobalt ferrite nanoparticles embedded in PAA hydrogel.

    PubMed

    van Berkum, Susanne; Dee, Joris T; Philipse, Albert P; Erné, Ben H

    2013-05-14

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network.

  6. Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel

    PubMed Central

    van Berkum, Susanne; Dee, Joris T.; Philipse, Albert P.; Erné, Ben H.

    2013-01-01

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

  7. Short stimulation of electro-responsive PAA/fibrin hydrogel induces collagen production.

    PubMed

    Rahimi, Nastaran; Swennen, Geertje; Verbruggen, Sanne; Scibiorek, Martyna; Molin, Daniel G; Post, Mark J

    2014-09-01

    Acrylic acid/fibrin hydrogel can mechanically stimulate cells when an external electrical field is applied, enabling them to migrate and align throughout the depth of the gel. The ability of electro-responsive polyacrylic acid (PAA)/fibrin hydrogel to promote collagen production and remodeling has been investigated by three-dimensional (3D) culturing and conditioning of smooth muscle cells (SMCs). SMCs-seeded hydrogels were subjected to an alternating electrical field (0.06 V/mm) for 2 h for one, two, or three times per week during 4 weeks of culturing. Fluorescent images of collagen structure and accumulation, assessed by CNA-35 probe, showed increased collagen content (>100-fold at 1× stimulation/week) in the center of the hydrogels after 4 weeks of culture. The increase in collagen production correlated with increasing extracellular matrix gene expression and resulted in significantly improved mechanical properties of the stimulated hydrogels. Matrix metalloproteinase (MMP)-2 activity was also significantly enhanced by stimulation, which probably has a role in the reorganization of the collagen. Short stimulation (2 h) induced a favorable response in the cells and enhanced tissue formation and integrity of the scaffold by inducing collagen production. The presented set up could be used for conditioning and improving the functionality of current tissue-engineered vascular grafts.

  8. Investigation of PAA/PVDF-NZVI hybrids for metronidazole removal: synthesis, characterization, and reactivity characteristics.

    PubMed

    Yang, Jiacheng; Wang, Xiangyu; Zhu, Minping; Liu, Huiling; Ma, Jun

    2014-01-15

    For the first time, the removal process of metronidazole (MNZ) from aqueous solutions over nano zerovalent iron (NZVI) encapsulated within poly(acrylic acid) (PAA)/poly(vinylidene fluoride) (PVDF) membranes was reported. The resultant composite (PPN) demonstrated high reactivity, excellent stability and reusability over the reaction course. Such excellent performance might be attributed to the presence of the charged carboxyl groups in PVDF membrane support, which could enhance NZVI dispersion and improve its longevity. Results showed that a lower initial concentration and higher reaction temperature facilitated the removal of MNZ by PPN, and that the acidic and neutral conditions generally exhibited more favorable effect on MNZ removal than the alkaline ones. Kinetics of the MNZ removal by PPN was found to follow a two-parameter pseudo-first-order decay model well, and the activation energy of the MNZ degradation by PPN was determined to be 30.49kJ/mol. The presence of chloride ions slightly enhanced the reactivity of PPN with MNZ, whereas sulfate ions inhibited its reactivity. In addition, MNZ degradation pathways by PPN were proposed based on the identified intermediates. This study suggests that PPN composite possessing excellent performance may be a promising functional material to pretreat antibiotic wastewaters. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. New Stable Cu(I) Catalyst Supported on Weakly Acidic Polyacrylate Resin for Green C-N Coupling: Synthesis of N-(Pyridin-4-yl)benzene Amines and N,N-Bis(pyridine-4-yl)benzene Amines.

    PubMed

    Kore, Nitin; Pazdera, Pavel

    2016-12-22

    A method for preparation of a new stable Cu(I) catalyst supported on weakly acidic polyacrylate resin without additional stabilizing ligands is described. A simple and efficient methodology for Ullmann Cu(I) catalyzed C-N cross coupling reactions using this original catalyst is reported. Coupling reactions of 4-chloropyridinium chloride with anilines containing electron donating (EDG) or electron withdrawing (EWG) groups, naphthalen-2-amine and piperazine, respectively, are successfully demonstrated.

  10. Degradation of Sodium-Polyacrylate in Dilute Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Saita, Takao

    1980-12-01

    It is shown using a capillary viscometer that the viscosity of a dilute aqueous solution of sodium-polyacrylate at 20°C decreases gradually for each flow time measurement and also decreases with the time of rest. Assuming that the polymer degradation is caused by shearing stress and oxidation, their effects are discussed with the data obtained using a closed-type capillary viscometer derived for this investigation. It is proved from the results that rupture of the Na-PAA molecule is caused by mechanochemical degradation, and also photo-degradation under the usual illumination and sunlight in a laboratory.

  11. Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO2) and their by-products hydrogen peroxide (H2O2) and chlorite (ClO2(-)).

    PubMed

    Chhetri, Ravi Kumar; Baun, Anders; Andersen, Henrik Rasmus

    2016-12-01

    Environmental effect evaluation of disinfection of combined sewer overflow events with alternative chemical disinfectants requires that the environmental toxicity of the disinfectants and the main by-products of their use are known. Many disinfectants degrade quickly in water which should be included in the evaluation of both their toxicity as determined in standardized tests and their possible negative effect in the water environment. Here we evaluated according to the standardized ISO 8692 test the toxicity towards the green microalgae, Pseudokirchneriella subcapitata, of three disinfectants: performic acid (PFA), peracetic acid (PAA) and chlorine dioxide (ClO2) as well as two by-products of their use: hydrogen peroxide (H2O2) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC50 values ranged from 0.16 to 2.9mg/L based on nominal concentrations leading to the labeling of the chemicals as either toxic or very toxic. The five investigated chemicals decreased in toxicity in the order chlorine dioxide, performic acid, peracetic acid, chlorite and hydrogen peroxide. The stability of the chemicals increased in the same order as the toxicity decrease. This indicates that even though ClO2 has the highest environmental hazard potential, it may still be suitable as an alternative disinfectant due to its rapid degradation in water.

  12. Poly(acrylic acid) Bridged Gadolinium Metal-Organic Framework-Gold Nanoparticle Composites as Contrast Agents for Computed Tomography and Magnetic Resonance Bimodal Imaging

    PubMed Central

    Tian, Chixia; Zhu, Liping; Lin, Feng; Boyes, Stephen G.

    2015-01-01

    Imaging contrast agents for magnetic resonance imaging (MRI) and computed tomography (CT) have received significant attention in the development of techniques for early-stage cancer diagnosis. Gadolinium (Gd) (III), which has seven unpaired electrons and a large magnetic moment, can dramatically influence the water proton relaxation and hence exhibits excellent MRI contrast. On the other hand, gold (Au), which has a high atomic number and high x-ray attenuation coefficient, is an ideal contrast agent candidate for x-ray based CT imaging. Gd metal organic framework (MOF) nanoparticles with tunable size, high Gd (III) loading and multivalency can potentially overcome the limitations of clinically utilized Gd chelate contrast agents. In this work, we report for the first time the integration of GdMOF nanoparticles with gold nanoparticles (AuNPs) for the preparation of a MRI/CT bimodal imaging agent. Highly stable hybrid GdMOF/AuNPs composites have been prepared by using poly(acrylic acid) as a bridge between the GdMOF nanoparticles and AuNPs. The hybrid nanocomposites were then evaluated in MRI and CT imaging. The results revealed high longitudinal relaxivity in MRI and excellent CT imaging performance. Therefore, these GdMOF/AuNPs hybrid nanocomposites potentially provide a new platform for the development of multi-modal imaging probes. PMID:26147906

  13. Effects of added surfactant on swelling and molecular transport in drug-loaded tablets based on hydrophobically modified poly(acrylic acid).

    PubMed

    Knöös, Patrik; Wahlgren, Marie; Topgaard, Daniel; Ulvenlund, Stefan; Piculell, Lennart

    2014-08-14

    A combination of NMR chemical shift imaging and self-diffusion experiments is shown to give a detailed molecular picture of the events that occur when tablets of hydrophobically modified poly(acrylic acid) loaded with a drug (griseofulvin) swell in water in the presence or absence of surfactant (sodium octylbenzenesulfonate). The hydrophobic substituents on the polymer bind and trap the surfactant molecules in mixed micelles, leading to a slow effective surfactant transport that occurs via a small fraction of individually dissolved surfactant molecules in the water domain. Because of the efficient binding of surfactant, the penetrating water is found to diffuse past the penetrating surfactant into the polymer matrix, pushing the surfactant front outward as the matrix swells. The added surfactant has little effect on the transport of drug because both undissolved solid drug and surfactant-solubilized drug function as reservoirs that essentially follow the polymer as it swells. However, the added surfactant nevertheless has a strong indirect effect on the release of griseofulvin, through the effect of the surfactant on the solubility and erosion of the polymer matrix. The surfactant effectively solubilizes the hydrophobically modified polymer, making it fully miscible with water, leading to a more pronounced swelling and a slower erosion of the polymer matrix.

  14. Preparation and characterization of poly(acrylic acid)—corn starch blend for use as chemical sand-fixing materials

    NASA Astrophysics Data System (ADS)

    Dang, Xugang; Chen, Hui; Shan, Zhihua

    2017-07-01

    One chemical sand-fixing materials based on poly(acrylic acid)-corn starch (PACS) blend was studied in this work. The PACS blend was prepared by solution mixing method between PA and CS. In order to prepare sand-fixing materials for environmental applications using the well-established method of spraying evenly PACS blend solution on the surfaces of fine sand. Fourier transform infrared spectroscopy (FT-IR) revealed the existence of the intermolecular interactions between the blend components. Scanning electron microscope (SEM) analysis showed a continuous phase of blend, and it also showed the good sand-fixing capacity. The test results of hygroscopicity and water retention experiments indicated that the blends had excellent water-absorbing and water-retention capacity. The results of contact angle measurements between the PACS solutions and fine sand showed that the PACS blend has a satisfactory effect on fine sand wetting. And the PACS, as a sand-fixation material, has excellent sand-fixation rate up to 99.5%.

  15. Effects of poly(L-lysine), poly(acrylic acid) and poly(ethylene glycol) on the adhesion, proliferation and chondrogenic differentiation of human mesenchymal stem cells.

    PubMed

    Lu, Hongxu; Guo, Likun; Kawazoe, Naoki; Tateishi, Tetsuya; Chen, Guoping

    2009-01-01

    Microenvironments, composed of many kinds of cytokines and growth factors plus extracellular matrices with diverse electrostatic properties, play key roles in controlling cell functions in vivo. In this study, three kinds of water-soluble polymers, positively charged poly(L-lysine) (PLL), negatively charged poly(acrylic acid) (PAAc) and neutral poly(ethylene glycol) (PEG), were compared based on their effects on the adhesion, spread, proliferation and chondrogenic differentiation of human mesenchymal stem cells (MSCs). The MSCs were seeded and cultured in the presence of polymers of different concentrations applied by methods using coating, mixing or covering. The effects of the water-soluble polymers depended on their electrostatic properties and method of application. The methods were in the order of coating, mixing and covering in terms of high to low influence. A low concentration of PLL promoted MSC adhesion, spread, proliferation and chondrogenic differentiation, while a high concentration of PLL was toxic. The PEG-coated surface facilitated cell aggregation and spheroid formation by inhibiting cell adhesion. A high concentration of mixed PEG (10 microg/ml) promoted cell proliferation in serum-free medium. PAAc showed no obvious effects on MSC adhesion, spread, proliferation, or chondrogenic differentiation.

  16. Conducting polymer films fabricated by oxidative graft copolymerization of aniline on poly(acrylic acid) grafted poly(ethylene terephthalate) surfaces.

    PubMed

    Wang, Jiku; Liu, Xuyan; Choi, Ho-Suk; Kim, Jong-Hoon

    2008-11-27

    A conductive polyaniline/poly(ethylene terephthalate) (PANI/PET) composite film was fabricated via the oxidative graft copolymerization of aniline (ANI) onto the plasma-induced poly(acrylic acid) (PAAc) grafted PET surface. The attenuated total reflectance Fourier transform infrared spectroscopy spectra (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) results confirmed that PANI was successfully grafted onto the surface of the PAAc-g-PET films. The effects of the experimental conditions on the percentage of PANI grafted onto the PAAc-g-PET films were extensively investigated. A very high grafting percentage of ANI can be obtained through the acid-base reaction between the aniline monomer and PAAc on the PAAc-g-PET surface at high temperature. As a result, the grafting percentage of PANI can be increased to as high as 12.18 wt %, which causes the surface resistance of the PANI-g-PAAc-g-PET film to be reduced to about 1000 Omega/sq. We predicted that this is because of the high flexibility of the PAAc molecular chains and high solubility of aniline, both of which facilitate the binding of aniline to PAAc during this high temperature acid-base reaction. It was observed by atomic force microscopy (AFM) that the PANI-modified PET surface exhibits higher size irregularity and surface roughness, which further indicated that a much greater number of aniline molecules can be reactively bonded to and distributed along the grafted AAc chains and that the PANI-g-PAAc-g-PET surface resulting from the sequential oxidative graft copolymerization can possess higher electrical conductivity.

  17. Investigations of PAA degradation in aqueous solutions: Impacts of water hardness, salinity and DOC

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) is used in aquaculture under various conditions for disinfection purposes. However, there is lack of information about its environmental fate. Therefore, the impact of water hardness, salinity, and dissolved organic carbon (DOC) on PAA-degradation within 5 hours was investigat...

  18. Assessment of the attenuation of an intra-abdominal vein by use of a silicone-polyacrylic acid gradual venous occlusion device in dogs and cats.

    PubMed

    Wallace, Mandy L; Ellison, Gary W; Giglio, Robson F; Batich, Christopher D; Berry, Clifford R; Case, J Brad; Kim, Stanley E

    2016-06-01

    OBJECTIVE To evaluate the closure rate and completeness of closure for a silicone-polyacrylic acid gradual venous occlusion device placed around an intra-abdominal vein to simulate gradual occlusion of an extrahepatic portosystemic shunt. ANIMALS 3 purpose-bred cats and 2 purpose-bred dogs. PROCEDURES The device was surgically placed around an external (cats) or internal (dogs) iliac vein. Computed tomographic angiography was performed at the time of surgery and 2, 4, and 6 weeks after surgery. Ultrasonographic examinations of blood flow through the vein within the device were performed at the time of surgery and at weekly intervals thereafter. Dogs were euthanized 6 weeks after surgery, and the external iliac veins were harvested for histologic examination. RESULTS The prototype gradual venous occlusion device was successfully placed in all animals, and all animals recovered without complications following the placement procedure. The vessel was completely occluded in 2 cats by 6 weeks after surgery, as determined on the basis of results of CT and ultrasonography; there was incomplete occlusion with a luminal diameter of 1.5 mm in the other cat by 6 weeks after surgery. The vessel was completely occluded in both dogs by 6 weeks after surgery. Histologic examination of the external iliac veins obtained from the dogs revealed minimal inflammation of the vessel wall and no thrombus formation. CONCLUSIONS AND CLINICAL RELEVANCE The prototype device induced gradual attenuation of an intra-abdominal vessel over a 6-week period. This device may provide another option for gradual occlusion of extrahepatic portosystemic shunts.

  19. The outcomes of two different bulking agents (dextranomer hyaluronic acid copolymer and polyacrylate-polyalcohol copolymer) in the treatment of primary vesico-ureteral reflux

    PubMed Central

    Taşkinlar, Hakan; Avlan, Dincer; Bahadir, Gokhan Berktug; Delibaş, Ali; Nayci, Ali

    2016-01-01

    ABSTRACT Purpose Subureteral injection of bulking agents in the endoscopic treatment of vesicoureteral reflux is widely accepted therapy with high success rates. Although the grade of vesicoureteric reflux and experience of surgeon is the mainstay of this success, the characteristics of augmenting substances may have an effect particularly in the long term. In this retrospective study, we aimed to evaluate the clinical outcomes of the endoscopic treatment of vesicoureteric reflux (VUR) with two different bulking agents: Dextranomer/hyaluronic acid copolymer (Dx/HA) and Polyacrylate polyalcohol copolymer (PPC). Materials and Methods A total 80 patients (49 girls and 31 boys) aged 1-12 years (mean age 5.3 years) underwent endoscopic subureteral injection for correction of VUR last six years. The patients were assigned to two groups: subureteral injections of Dx/HA (45 patients and 57 ureters) and PPC (35 patients and 45 ureters). VUR was grade II in 27 ureters, grade III in 35, grade IV in 22 and grade V in 18 ureters. Results VUR was resolved in 38 (66.6%) of 57 ureters and this equates to VUR correction in 33 (73.3%) of the 45 patients in Dx/HA group. In PPC group, overall success rate was 88.8% (of 40 in 45 ureters). Thus, Thus, this equates to VUR correction in 31 (88.5%) of the 35 patients. Conclusions Our short term data show that two different bulking agent injections provide a high level of reflux resolution and this study revealed that success rate of PPC was significantly higher than Dx/HA with less material. PMID:27286115

  20. Polyacrylate bound TiSb2 electrodes for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Gómez-Cámer, Juan Luis; Novák, Petr

    2015-01-01

    Crystalline TiSb2 electrodes prepared using two different binders, PVDF and lithium polyacrylate (LiPAA), were examined as negative electrodes in Li-ion batteries. The cycle life of the electrodes is strongly influenced by the choice of the binder, reaching ca. 120 cycles with LiPAA vs. ca. 90 cycles achieved with the common binder PVDF. Moreover, rate capability is improved using LiPAA binder. The reduction in TiSb2 particle size is shown to influence the average practical specific charge at high charge/discharge rates. The reasons for this improvement are discussed and the optimized electrode was demonstrated in full Li-ion cells.

  1. Calcium Phosphate Mineralization in Cellulose Derivative/Poly(acrylic acid) Composites Having a Chiral Nematic Mesomorphic Structure.

    PubMed

    Ogiwara, Takuya; Katsumura, Ayaka; Sugimura, Kazuki; Teramoto, Yoshikuni; Nishio, Yoshiyuki

    2015-12-14

    Calcium phosphate mineralization was conducted by using polymer composites of liquid-crystalline (ethyl)cellulose (EC) or (hydroxypropyl)cellulose (HPC) with poly(acrylic acid) (PAA) as a scaffolding medium for the inorganic deposition. The EC/PAA and HPC/PAA samples were prepared in colored film form from EC and HPC lyotropic liquid crystals of left-handed and right-handed chiral nematics, respectively, by polymerization and cross-linking of acrylic acid as the main solvent component. The mineralization was allowed to proceed in a batchwise operation by soaking the liquid-crystalline films in an aqueous salt solution containing the relevant ions, Ca(2+) and HPO4(2-). The calcium phosphate-deposited EC/PAA and HPC/PAA composites (weight gain, typically 15-25% and 6-11%, respectively) retained the chiral nematic organization of the respective original handedness but exhibited selective light-reflection of longer wavelengths relative to that of the corresponding nonmineralized samples. From X-ray diffraction and energy-dispersive X-ray spectroscopy measurements, it was deduced that the calcium and phosphorus were incorporated inside the polymer matrices in three forms: amorphous calcium phosphate, hydroxyapatite, and a certain complex of PAA-Ca(2+). Dynamic mechanical analysis and thermogravimetry revealed that the inorganic hybridization remarkably enhanced the thermal and mechanical performance of the optically functionalized cellulosic/synthetic polymer composites; however, the effect was more drastic in the EC/PAA series rather than the HPC/PAA series, reflecting the difference in the deposited mineral amount between the two.

  2. Effect of pH on the physico-mechanical properties and miscibility of methyl cellulose/poly(acrylic acid) blends.

    PubMed

    Negim, E S M; Nurpeissova, Zh A; Mangazbayeva, R A; Khatib, J M; Williams, C; Mun, G A

    2014-01-30

    The miscibility behavior and physico-mechanical properties between methyl cellulose (MC) of different molecular weights (4 × 10(4) and 8.3 × 10(4)g/mol) and poly(acrylic acid) (PAA) were studied by viscometry, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), tensile strength and scanning electron microscopy (SEM) using water as a solvent. Various formulations were designed to investigate the effects of process variables such as pH on the physico-mechanical and miscibility properties of MC/PAA blends. The rheological features for the obtained blends are strongly dependent on the molecular weight of the MC used and pH. The viscosity measurements showed that all blends have non-Newtonian shear thinning (pseudoplastic) behavior. These blends have a single glass transition indicating that these blends are able to form a miscible phase due to the formation of hydrogen bonds between the hydroxyl group of MC and the carboxyl group of PAA. The MC/PAA blends exhibit good mechanical properties, thermal stability, characteristics of a MC-PAA polymer network. SEM of the blends showed no phase separation, when compared with the pure MC and PAA. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Protein immobilization onto poly(acrylic acid) functional macroporous polyHIPE obtained by surface-initiated ARGET ATRP.

    PubMed

    Audouin, Fabrice; Larragy, Ruth; Fox, Mary; O'Connor, Brendan; Heise, Andreas

    2012-11-12

    Amino-functional macroporous monoliths from polymerized high internal phase emulsion (polyHIPE) were surface modified with initiators for atom transfer radical polymerization (ATRP). The ATRP initiator groups on the polyHIPE surface were successfully used to initiate activator regeneration by electron transfer (ARGET) ATRP of (meth)acrylic monomers, such as methyl methacrylate (MMA) or tert-butyl acrylate (tBA) resulting in a dense coating of polymers on the polyHIPE surface. Addition of sacrificial initiator permitted control of the amount of polymer grafted onto the monolith surface. Subsequent removal of the tert-butyl protecting groups yielded highly functional polyHIPE-g-poly(acrylic acid). The versatility to use the high density of carboxylic acid groups for secondary reactions was demonstrated by the successful conjugation of enhanced green fluorescent protein (eGFP) and coral derived red fluorescent protein (DsRed) using EDC/sulfo-NHS chemistry, on the polymer 3D-scaffold surface. The materials and methodologies presented here are simple and robust, thus, opening new possibilities for the bioconjugation of highly porous polyHIPE for bioseparation applications.

  4. In situ synthesis of high swell ratio polyacrylic acid/silver nanocomposite hydrogels and their antimicrobial properties.

    PubMed

    Wei, Yi-Syuan; Chen, Ko-Shao; Wu, Lii-Tzu

    2016-11-01

    Silver nanocomposites embedded within a polymer matrix have attracted attention in recent years. Ionic polymer hydrogels comprise networks of chemically or physically cross-linked polymers that swell considerably in an appropriate solvent. In this study, we used a solution of the carboxylic monomer acrylic acid and silver nitrate to prepare nanocomposite hydrogels through ultraviolet (UV)-light irradiation. Silver-impregnated biomaterial composed of acrylic acid contains only a monomer and no cross-linker. The formation of hydrogels and reduction of silver nanoparticles were affected by the preparation parameters, that is, the monomer concentration and silver nitrate concentration. The morphology, structure, and size of the silver nanocomposite hydrogels were evaluated through field emission scanning electron microscopy and UV-visible absorption. The antimicrobial activity of the samples was tested against fourstandard strains Candida albicans, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli; and five clinical bacterial isolates Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumonia. The silver nanocomposite hydrogels exhibited an interconnected porous structure and could absorb 400 to 550g of deionized water per gram of dried hydrogel. Moreover, these hydrogels produced a strong antibacterial effect, which can be useful in developing new superabsorbent antimicrobial pharmaceutical products. Copyright © 2016. Published by Elsevier Inc.

  5. DNA microarray fabricated on poly(acrylic acid) brushes-coated porous silicon by in situ rolling circle amplification.

    PubMed

    Wang, Cuie; Jia, Xue-Mei; Jiang, Chuan; Zhuang, Guang-Nan; Yan, Qin; Xiao, Shou-Jun

    2012-10-07

    Microarrays hold considerable promise in large-scale biology on account of their analytical, massive and parallel nature. In a step toward further enabling such a capability, we describe the application of rolling circle amplification (RCA) for a sensitive and multiplex detection of nucleic acid targets on oligonucleotide-conjugated polymer brushes covalently grown from porous silicon. Both RCA and polymer brushes have been taken to increase the loading quantity of target molecules and thus improve the detection sensitivity without loss of multiplexing. Besides, polymer brushes were employed to protect porous silicon and to provide biologically simulated environments, making the attached biomolecules maintain bioactivity. This approach can reach a detection limit of 0.1 nM target analytes and three orders of magnitude dynamic range of 0.1-100 nM, with a fluorescence scanner. A two-colour DNA microarray was achieved via RCA of two kinds of circular DNA targets on one chip simultaneously. The porous silicon chip-based RCA technique is promising for the multiplex detection of deoxynucleic acids on microarrays.

  6. Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

    NASA Astrophysics Data System (ADS)

    Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat; Amin, Mohd. Cairul Iqbal Mohd

    2014-09-01

    The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.

  7. Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

    SciTech Connect

    Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat; Amin, Mohd. Cairul Iqbal Mohd

    2014-09-03

    The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.

  8. Involvement of the TetR-Type Regulator PaaR in the Regulation of Pristinamycin I Biosynthesis through an Effect on Precursor Supply in Streptomyces pristinaespiralis

    PubMed Central

    Zhao, Yawei; Feng, Rongrong; Zheng, Guosong; Tian, Jinzhong; Ruan, Lijun; Ge, Mei; Jiang, Weihong

    2015-01-01

    ABSTRACT Pristinamycin I (PI), produced by Streptomyces pristinaespiralis, is a streptogramin type B antibiotic, which contains two proteinogenic and five aproteinogenic amino acid precursors. PI is coproduced with pristinamycin II (PII), a member of streptogramin type A antibiotics. The PI biosynthetic gene cluster has been cloned and characterized. However, thus far little is understood about the regulation of PI biosynthesis. In this study, a TetR family regulator (encoded by SSDG_03033) was identified as playing a positive role in PI biosynthesis. Its homologue, PaaR, from Corynebacterium glutamicum serves as a transcriptional repressor of the paa genes involved in phenylacetic acid (PAA) catabolism. Herein, we also designated the identified regulator as PaaR. Deletion of paaR led to an approximately 70% decrease in PI production but had little effect on PII biosynthesis. Identical to the function of its homologue from C. glutamicum, PaaR is also involved in the suppression of paa expression. Given that phenylacetyl coenzyme A (PA-CoA) is the common intermediate of the PAA catabolic pathway and the biosynthetic pathway of l-phenylglycine (l-Phg), the last amino acid precursor for PI biosynthesis, we proposed that derepression of the transcription of paa genes in a ΔpaaR mutant possibly diverts more PA-CoA to the PAA catabolic pathway, thereby with less PA-CoA metabolic flux toward l-Phg formation, thus resulting in lower PI titers. This hypothesis was verified by the observations that PI production of a ΔpaaR mutant was restored by l-Phg supplementation as well as by deletion of the paaABCDE operon in the ΔpaaR mutant. Altogether, this study provides new insights into the regulation of PI biosynthesis by S. pristinaespiralis. IMPORTANCE A better understanding of the regulation mechanisms for antibiotic biosynthesis will provide valuable clues for Streptomyces strain improvement. Herein, a TetR family regulator PaaR, which serves as the repressor of the

  9. Superabsorbent nanocomposite synthesis of cellulose from rice husk grafted poly(acrylate acid-co-acrylamide)/bentonite

    NASA Astrophysics Data System (ADS)

    Helmiyati; Abbas, G. H.; Kurniawan, S.

    2017-04-01

    Superabsorbent nanocomposite synthesis of cellulose rice husk as the backbone with free radical polymerization method in copolymerization grafted with acrylic acid and acrylamide monomer. The cellulose was isolated from rice husk with mixture of toluene and ethanol and then hemicellulose and lignin were removed by using potassium hydroxide 4% and hydrogen peroxide 2%. The obtained cellulose rendement was 37.85%. The functional group of lignin analyzed by FTIR spectra was disappeared at wavenumber 1724 cm-1. Crystal size of the obtained isolated cellulose analyzed by XRD diffraction pattern was 34.6 nm, indicated the nanocrystal structure. Copolymerization was performed at temperature of 70°C with flow nitrogen gas. Initiator and crosslinking agent used were potassium persulfate and N‧N-methylene-bis-acrylamide. The swelling capacity of water and urea showed the results was quite satisfactory, the maximum swelling capacity in urea and water were 611.700 g/g and 451.303 g/g, respectively, and can be applied in agriculture to absorb water and urea fertilizer.

  10. Rapid removal of copper with magnetic poly-acrylic weak acid resin: quantitative role of bead radius on ion exchange.

    PubMed

    Fu, Lichun; Shuang, Chendong; Liu, Fuqiang; Li, Aimin; Li, Yan; Zhou, Yang; Song, Haiou

    2014-05-15

    A novel magnetic weak acid resin NDMC was self-synthesized for the removal of Cu(2+) from aqueous solutions. NDMC showed superior properties on the removal of Cu(2+) compared to commercial resins C106 and IRC-748, which was deeply investigated by adsorption isotherms and kinetic tests. The equilibrium adsorption amount of Cu(2+) onto NDMC (267.2mg/g) was almost twice as large as that onto IRC-748 (120.0mg/g). The adsorption kinetics of Cu(2+) onto the three resins fitted well with the pseudo-second-order equation. The initial adsorption rate h of NDMC was about 4 times that of C106 and nearly 8 times that of IRC-748 at the initial concentration of 500mg/L. External surface area was determined to be the key factor in rate-controlling by further analyzing the adsorption thermodynamics, kinetics parameters and physicochemical properties of the resins. NDMC resin with the smallest bead radius possessed the largest external surface and therefore exhibited the fastest kinetics. The adsorption amount of Cu(2+) onto NDMC was not influenced as the concentration of Na(+) increased from 1.0 to 10.0mM/L. Dilute HCl solution could effectively desorb Cu(2+). NDMC demonstrated high stability during 10 adsorption/desorption cycles, showing great potential in the rapid removal of Cu(2+) from wastewater.

  11. Surface functionalization of an osteoconductive filler by plasma polymerization of poly(ε-caprolactone) and poly(acrylic acid) films

    NASA Astrophysics Data System (ADS)

    Petisco-Ferrero, S.; Sánchez-Ilárduya, M. B.; Díez, A.; Martín, L.; Meaurio Arrate, E.; Sarasua, J. R.

    2016-11-01

    One of the major limitations found in the use of nanocomposites based on synthetic hydroxyapatite and polymeric matrix for bone-tissue regeneration lies in the poor interfacial adhesion between the inorganic filler and the polymer matrix. The integrity of the nanocomposite is severely compromised since, on the one hand, high surface fillers tend to form aggregates and on the other, there is no chemical bonding between these two different categories of materials. Thus, customized surface functionalization stands as an effective route to improve the interfacial behaviour between particles and polymeric matrices. Amongst the current state of development of coating technologies, the high film-chemistry controllability offered by plasma polymerization technology enhances the synthesis of polymeric films from virtually any starting organic monomer. In this sense, the work presented here provides strong evidences of surface functionalization achieved by plasma polymerization starting respectively from ε-caprolactone and acrylic acid monomers. The chemistry of the deposited films has been descriptively analysed by XPS demonstrating outstanding retention of monomer functionalities and FTIR spectra of the deposited films revealed a high resemblance to those obtained by conventional synthesis. Results provided thereof are expected to significantly contribute to improve the interfacial behaviour in terms of matrix-reinforcement compatibilization, of crucial importance for bone-tissue engineering applications.

  12. Freshwater dispersion stability of PAA-stabilised cerium oxide nanoparticles and toxicity towards Pseudokirchneriella subcapitata.

    PubMed

    Booth, Andy; Størseth, Trond; Altin, Dag; Fornara, Andrea; Ahniyaz, Anwar; Jungnickel, Harald; Laux, Peter; Luch, Andreas; Sørensen, Lisbet

    2015-02-01

    An aqueous dispersion of poly (acrylic acid)-stabilised cerium oxide (CeO₂) nanoparticles (PAA-CeO₂) was evaluated for its stability in a range of freshwater ecotoxicity media (MHRW, TG 201 and M7), with and without natural organic matter (NOM). In a 15 day dispersion stability study, PAA-CeO₂ did not undergo significant aggregation in any media type. Zeta potential varied between media types and was influenced by PAA-CeO₂ concentration, but remained constant over 15 days. NOM had no influence on PAA-CeO₂ aggregation or zeta potential. The ecotoxicity of the PAA-CeO₂ dispersion was investigated in 72 h algal growth inhibition tests using the freshwater microalgae Pseudokirchneriella subcapitata. PAA-CeO₂ EC₅₀ values for growth inhibition (GI; 0.024 mg/L) were 2-3 orders of magnitude lower than pristine CeO₂ EC₅₀ values reported in the literature. The concentration of dissolved cerium (Ce(3+)/Ce(4+)) in PAA-CeO₂ exposure suspensions was very low, ranging between 0.5 and 5.6 μg/L. Free PAA concentration in the exposure solutions (0.0096-0.0384 mg/L) was significantly lower than the EC10 growth inhibition (47.7 mg/L) value of pure PAA, indicating that free PAA did not contribute to the observed toxicity. Elemental analysis indicated that up to 38% of the total Cerium becomes directly associated with the algal cells during the 72 h exposure. TOF-SIMS analysis of algal cell wall compounds indicated three different modes of action, including a significant oxidative stress response to PAA-CeO₂ exposure. In contrast to pristine CeO₂ nanoparticles, which rapidly aggregate in standard ecotoxicity media, PAA-stabilised CeO₂ nanoparticles remain dispersed and available to water column species. Interaction of PAA with cell wall components, which could be responsible for the observed biomarker alterations, could not be excluded. This study indicates that the increased dispersion stability of PAA-CeO₂ leads to an increase in toxicity compared to

  13. Advantages and limitations of the use of an extended polyelectrolyte model to describe the proton-binding process in macromolecular systems. Application to a poly(acrylic acid) and a humic acid.

    PubMed

    García-Mina, Jose M

    2007-05-03

    A number of studies have shown the suitability of the polyelectrolyte model to describe the proton-binding behavior of macromolecules. This model, however, has two limitations associated with its theoretical approach: (1) it does not consider the possible heterogeneity of binding sites, and (2) for certain calculations, it involves the need to assume a specific molecular geometry. In this article we describe the theoretical basis of an extension of the polyelectrolyte model that removes the two limitations described above. Likewise, we discuss the advantages and limitations of the extended polyelectrolyte model (EPM) through its application to describe the proton-binding process in a well-characterized macromolecular system (a poly(acrylic acid)) and a complex molecular system (a humic acid). The results obtained showed the suitability of EPM to describe proton-binding processes in complex molecular systems without the need to assume previously a specific molecular geometry and explicitly considering the possible heterogeneity of the binding sites. The results obtained indicated that the field effects associated with the conformational structure corresponding to each ionic strength, even in the discharged state, affect the values of the intrinsic constants defining the proton-binding process using EPM. Likewise, EPM analysis reveals the significant influence of both the surface charge density and the molecular size on the value of the electrostatic effects affecting the values of the intrinsic constants in the proton-binding process.

  14. Controlled Transdermal Iontophoresis by Polypyrrole/Poly(Acrylic Acid) Hydrogel

    NASA Astrophysics Data System (ADS)

    Chansai, Phithupha; Sirivat, Anuvat

    2008-03-01

    Transdermal drug delivery system delivers a drug into a body at desired site and rate. The conductive polymer-hydrogel blend between polypyrrole (PPy) doped with anionic drug and poly(acrylic acid) (PAA) were developed as a matrix/carrier of drug for the transdermal drug delivery in which the characteristic releases depend on the electrical field applied. The PAA films and their blend films were prepared by solution casting using ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent. A mechanical blending of PPy particles and PAA matrix was then carried out. Drug diffusions in the blended PPy/PAA hydrogel and the non-blended one were investigated and determined by using a modified Franz-diffusion cell with an acetate buffer, pH 5.5, at 37 0C, for a period of 48 hours to determine the effects of crosslinking ratio and electric field strength. Amounts of the released drug were measured by UV-Visible spectrophotometry. The diffusion coefficient of drug was determined through the Higuchi equation via different conditions, with and without an electric field. Moreover, thermal properties and electrical conductivity of the polypyrrole and drug-loaded polypyrrole were investigated by means of the thermogravimetric analysis and by using a two-point probe meter, respectively.

  15. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... grafted copolymer of cross-linked sodium polyacrylate identified as 2-propenoic acid, polymers with N,N-di-2-propenyl-2-propen-1-amine and hydrolyzed polyvinyl acetate, sodium salts, graft (CAS Reg. No...-propanediyl di-2-propenoate and sodium 2-propenoate (CAS Reg. No. 76774-25-9). (b) Adjuvants. The copolymers...

  16. 21 CFR 173.73 - Sodium polyacrylate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium polyacrylate. 173.73 Section 173.73 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.73 Sodium polyacrylate. Sodium... “Determination of Weight Average and Number Average Molecular Weight of Sodium Polyacrylate,” which is...

  17. 21 CFR 173.73 - Sodium polyacrylate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium polyacrylate. 173.73 Section 173.73 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.73 Sodium polyacrylate. Sodium... “Determination of Weight Average and Number Average Molecular Weight of Sodium Polyacrylate,” which is...

  18. Bio-inspired self-cleaning PAAS hydrogel released coating for marine antifouling.

    PubMed

    Xue, Lili; Lu, Xili; Wei, Huan; Long, Ping; Xu, Jina; Zheng, Yufeng

    2014-05-01

    In this paper, an antifouling hydrogel coating of slippery hydrogel-released hydrous surface (SHRHS) with the self-cleaning ability of oil-resistance and self-regeneration characters was designed. A physical blending method of loading Sodium polyacrylate (PAAS) powder into the organic silicon resin was employed to prepare the SHRHS coating. The oil-resistance of the intact and scratch SHRHS coatings was performed by time-sequence images of washing dyed beef tallow stain away. The results showed that the SHRHS coating has the greater ability of stain removal. The concentration of Na+ ions released from PAAS hydrogel on the surface of the SHRHS coating was investigated by ion chromatograph (IC). The results revealed that the coating had the ability of self-regeneration by PAAS hydrogel continuously peeling. The biomass of two marine microalgae species, Nitzschia closterium f. minutissima and Navicula climacospheniae Booth attached on the SHRHS was investigated using UV-Visible Spectrophotometer (UV) and Scanning electron microscopy (SEM). The results showed that the microalgaes attached a significantly lower numbers on the SHRHS in comparison with the organic silicon coating. In order to confirm the antifouling ability of the SHRHS coating, the field trials were carried out for 12weeks. It showed that the SHRHS may provide an effective attachment resistance to reduce biofouling.

  19. Recovery of nickel from aqueous solutions by complexation-ultrafiltration process with sodium polyacrylate and polyethylenimine.

    PubMed

    Shao, Jiahui; Qin, Shu; Davidson, Joshua; Li, Wenxi; He, Yiliang; Zhou, H Susan

    2013-01-15

    The recovery of nickel from aqueous dilute solutions by complexation-ultrafiltration process with sodium polyacrylate (PAAS) and polyethylenimine (PEI) was studied. Experiments were performed as a function of aqueous pH, polymer/Ni(2+) ratio and background electrolyte concentration. At optimum experimental conditions, the nickel removal rate reaches 99.5% using PAAS and 93.0% using PEI as the complexation agent. The nickel removal rate was found to decrease as the adding salt NaCl concentration increases for both complexation agents. A series of experiments implied that the mechanism could be the compressing electric double layer other than the competitive complexation. Diafiltration technique was further performed to regenerate complexation agents and recover nickel. The nickel removal rates were found to be close to those obtained with the original PEI and PAAS. Finally, Langmuir-type binding isotherm equation was employed to evaluate the extent of nickel bound to PAAS and PEI. The overall results from the two-step process of complexation-UF and decomplexation-UF separation showed that it could be a promising method for nickel removal and recovery from aqueous solutions. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Phosphoric acid esters cannot replace polyvinylphosphonic acid as phosphoprotein analogs in biomimetic remineralization of resin-bonded dentin

    PubMed Central

    Mai, Sui; Kim, Young Kyung; Toledano, Manuel; Breschi, Lorenzo; Ling, Jun Qi; Pashley, David H.; Tay, Franklin R.

    2009-01-01

    Polyvinylphosphonic acid (PVPA), a biomimetic analog of phosphoproteins, is crucial for recruiting polyacrylic acid (PAA)-stabilized amorphous calcium phosphate nanoprecursors during biomimetic remineralization of dentin collagen matrices. This study tested the null hypothesis that phosphoric acid esters of methacrylates in dentin adhesives cannot replace PVPA during bimimetic remineralization of resin-dentin interfaces. Human dentin specimens were bonded with: I) XP Bond, an etch-and-rinse adhesive using moist bonding; II) XP Bond using dry bonding; and III) Adper Prompt L-Pop, a self-etching adhesive. The control medium contained only set Portland cement and a simulated body fluid (SBF) without any biomimetic analog. Two experimental Portland cement/SBF remineralization media were evaluated: the first contained PAA as the sole biomimetic analog, the second contained PAA and PVPA as dual biomimetic analogs. No remineralization of the resin-dentin interfaces could be identified from specimens immersed in the control medium. After 2–4 months in the first experimental medium, specimens exhibited either no remineralization or large crystal formation within hybrid layers. Only specimens immersed in the second remineralization medium produced nanocrystals that accounted for intrafibrillar remineralization within hybrid layers. The null hypothesis could not be rejected; phosphoric acid esters in dentin adhesives cannot replace PVPA during biomimetic remineralization of adhesive-bonded dentin. PMID:19481792

  1. Kinetics of chromium ion absorption by cross-linked polyacrylate films

    NASA Technical Reports Server (NTRS)

    May, C. E.

    1984-01-01

    Three cross-linked ion exchange membranes were studied as to their ability to absorb chromium ion from aqueous chromium III nitrate solutions. Attention was given to the mechanism of absorption, composition of the absorbed product, and the chemical bonding. The membranes were: calcium polyacrylate, polyacrylic acid, and a copolymer of acrylic acid and vinyl alcohol. For the calcium polyacrylate and the copolymer, parabolic kinetics were observed, indicating the formation of a chromium polyacrylate phase as a coating on the membrane. The rate of absorption is controlled by the diffusion of the chromium ion through this coating. The product formed in the copolymer involves the formation of a coordination complex of a chromium ion with 6 carboxylic acid groups from the same molecule. The absorption of the chromium ion by the polyacrylic acid membranes appears to be more complicated, involving cross-linking. This is due to the coordination of the chromium ion with carboxylic acid groups from more than one polymer molecule. The absorption rate of the chromium ion by the calcium salt membrane was found to be more rapid than that by the free polyacrylic acid membrane.

  2. Physical stability of l-ascorbic acid amorphous solid dispersions in different polymers: A study of polymer crystallization inhibitor properties.

    PubMed

    Christina, Belinda; Taylor, Lynne S; Mauer, Lisa J

    2015-10-01

    The effects of different polymer types on inhibiting the crystallization of ascorbic acid (VitC) from amorphous solid dispersions at various temperatures and relative humidities (RHs) were studied. Polymer properties (ability to form hydrogen bonds with VitC, hygroscopicity, and glass transition temperature (Tg)) were correlated to their crystallization inhibitor performance. Solid dispersions of VitC with different pectins, polyvinylpyrrolidone (PVP), and polyacrylic acid (PAA) were formed from lyophilized solutions. Crystallinity, VitC-polymer interactions, hygroscopicity, and Tg were determined using X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), moisture sorption isotherm, and differential scanning calorimetry (DSC) methods, respectively. XRPD amorphous VitC could not be formed by lyophilization in the absence of a polymer, nor in PAA dispersions, but could be formed in pectin and PVP dispersions. The VitC-pectin and PVP dispersions remained amorphous when stored at low RHs, but some crystallization occurred within one week at high RHs. Evidence of hydrogen bonding between VitC and both pectins and PVP, but not PAA, was found in FTIR spectra, and correlated better with physical stability than the Tg. The hygroscopicity of the polymer also influenced the stability of the amorphous VitC solid dispersions. A ranking of the polymer crystallization inhibitor properties was: PVP>pectin with lower degree of esterification (DE)>pectin with higher DE >PAA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Spray-On Polyaniline/Poly(acrylic acid) Electrodes with Enhanced Electrochemical Stability.

    PubMed

    Jeon, Ju-Won; Kwon, Se Ra; Li, Fei; Lutkenhaus, Jodie L

    2015-11-04

    Polyaniline (PANI)-based electrodes are promising candidates for energy storage, but their cycle life remains poor. Recent work suggests that secondary interactions may enhance polyaniline's electrochemical stability and cycle life, but evidence to date is not conclusive. Here, we investigate spray-assisted layer-by-layer assemblies containing polyaniline nanofibers (PANI NFs) or conventional PANI and poly(acrylic acid) (PAA), which provides hydrogen bonding and electrostatic interactions. This spray-on approach may be suitable for the deposition of PANI onto a variety of surfaces. The effects of PANI type, PAA pH, and PAA molecular weight on the growth behavior, conductivity, and electrochemical performance are examined. It is shown that LbL films with PANI NFs, higher molecular weight PAA, and lower PAA pH yield the thickest films, whereas the thinnest films come from conventional PANI assembled under similar conditions. Electron microscopy imaging and density measurements show that LbL films containing PANI NFs are very porous, whereas those containing conventional PANI are very dense (0.28 vs 1.33 g/cm(3), respectively). The difference in density dramatically affects the electrochemical properties in terms of capacity and long-term cycling behavior. Upon extended cycling, PANI NFs alone rapidly lose their electrochemical activity. On the other hand, PANI NF-based LbL films exhibited somewhat enhanced stability, and PANI-based LbL films were exceptionally stable, maintaining 94.7% of their capacity after 1000 cycles when cycled up to 4.2 V vs Li/Li(+). These results show that secondary interactions from PAA enhance stability, as does the selection of PANI type and the electrode's density.

  4. Comparison of acidic polymers for the removal of cobalt from water solutions by polymer assisted ultrafiltration.

    PubMed

    Dambies, Laurent; Jaworska, Agnieszka; Zakrzewska-Trznadel, Grazyna; Sartowska, Bozena

    2010-06-15

    In this study, three sulfonated water-soluble polymers based on poly(vinyl alcohol) of different molecular weights (10,000, 50,000 and 100,000 Da) were prepared and tested against commercially available poly(acrylic acid) for the removal of cobalt using polymer assisted ultrafiltration. High rejection rates were obtained between pH 3 and 6 with sulfonated poly(vinyl alcohol) (PVA 10,000 and 50,000 Da) whereas poly(acrylic acid) (PAA) of similar molecular weights performed rather poorly in this pH range. Sulfonation improved significantly sorption capability of PVA. Sulfonated PVA 10,000 was the best complexing agent with rejection rate above 95% between pH 3 and 6. For unmodified PVA the rejection rate was only 30-45% at pH 6 and there was no rejection at pH 3 at all. PAA rejection rate was above 90% at pH 6 and only about 10% at pH 3. Large scale experiment in cross-flow, continuous apparatus conducted by using PVA-SO(3)H 10,000 Da to remove (60)Co radioisotope from water solutions showed excellent results demonstrating the potential of this polymer to purify acidic radioactive wastes containing cobalt radioisotopes.

  5. Ultrasonic Velocity, Viscosity and Refractive Index Investigation on Interacting Blend Solutions of PAA (Poly Acrylic Acid) and PVA (Poly Vinyl Alcohol) in Solvent DMSO (Di methyl Sulphoxide)

    NASA Astrophysics Data System (ADS)

    Nagamani, Chakrala

    2010-11-01

    The present study provides a great insight into the major new research areas like Plasma research (which is yielding a greater understanding of the universe) and Nano Technology Research (which provides many practical uses like Drug Delivery System). The Ultrasonic Velocities, Viscosities and Refractive indices of Poly (Acrylic Acid) and Poly (Vinyl Alcohol) blends in DMSO solutions have been measured over a wide range of composition, concentration and at different temperatures. The variation of Ultrasonic Velocity, derived acoustical parameters, adiabatic compressibility, acoustic impedance, Rao number, molar compressibility and relaxation strength with composition of blend solution was found not linear. This non-linearity has been attributed to incompatibility in conformity with the earlier findings. This behavior was confirmed by Viscometric and interaction parameters studies, as well as by investigation of Refractive index studies. These investigations offer an entirely new and simple approach to the study of the compatibility of polymer blends which is in general obtained by sophisticated techniques of thermal dynamic mechanical and electron microscopic analysis.

  6. Encapsulation of methotrexate and cyclophosphamide in interpolymer complexes formed between poly acrylic acid and poly ethylene glycol on multi-walled carbon nanotubes as drug delivery systems.

    PubMed

    Azqhandi, Mohammad Hossein Ahmadi; Farahani, Bahman Vasheghani; Dehghani, Nasibe

    2017-10-01

    By combining the advantage of multi-walled carbon nanotubes (MWCNTs) and interpolymer complexes, we synthesis a new carrier system consist of poly(acrylic acid)/poly(ethylene glycol)/carbon nanotube (PAA/PEG/CNT). Then, Methotrexate (MTX) and Cyclophosphamide (CPP) were loaded on PAA/PEG/CNT, and the physicochemical properties of nanoparticles characterized by Infrared spectroscopy (IR), Scanning Electron Microscopy (SEM), Thermo Gravimetric Analysis (TGA) and Nuclear Magnetic Resonance (NMR). In the second part after efficiency determination of loaded drugs, in vitro drug release study was examined with ultra violet spectroscopy (UV) in pH=7.4 buffer (human body range) and pH=4 buffer (pH of cancer cells), and fever temperature drug release kinetic was studied by different mathematical models. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Deflocculation of clay suspensions using sodium polyacrylates

    NASA Technical Reports Server (NTRS)

    Jedlicka, P.

    1984-01-01

    Rheological properties of elutriated kaolin suspensions deflocculated by Na polyacrylate (DAC 3 and DAC 4) were studied and compared to those deflocculated by the conventional Na2CO3 water and glass and imported Dispex N40. The deflocculating effect of Na polyacrylate was comparable to that of Dispex N40. The optimum amounts of Na polyacrylate were determined for suspensions based on 5-type kaolin. The Na polyacrylate can be successfully used for decreasing the water content of ceramic slips for casting and spray drying.

  8. Solvent effects on the formation of nanoparticles and multilayered coatings based on hydrogen-bonded interpolymer complexes of poly(acrylic acid) with homo- and copolymers of N-vinyl pyrrolidone.

    PubMed

    Zhunuspayev, Daulet E; Mun, Grigoriy A; Hole, Patrick; Khutoryanskiy, Vitaliy V

    2008-12-02

    The formation of hydrogen-bonded interpolymer complexes between poly(acrylic acid) and poly(N-vinyl pyrrolidone) as well as amphiphilic copolymers of N-vinyl pyrrolidone with vinyl propyl ether has been studied in aqueous and organic solutions. It was demonstrated that introduction of vinyl propyl ether units into the macromolecules of the nonionic polymer enhances their ability to form complexes in aqueous solutions due to more significant contribution of hydrophobic effects. The complexation was found to be a multistage process that involves the formation of primary polycomplex particles, which further aggregate to form spherical nanoparticles. Depending on the environmental factors (pH, solvent nature), these nanoparticles may either form stable colloidal solutions or undergo further aggregation, resulting in precipitation of interpolymer complexes. In organic solvents, the intensity of complex formation increases in the following order: methanol < ethanol < isopropanol < dioxane. The multilayered coatings were developed using layer-by-layer deposition of interpolymer complexes on glass surfaces. It was demonstrated that the solvent nature affects the efficiency of coating deposition.

  9. Preparation of chitosan/poly(acrylic acid) magnetic composite microspheres and applications in the removal of copper(II) ions from aqueous solutions.

    PubMed

    Yan, Han; Yang, Lingyun; Yang, Zhen; Yang, Hu; Li, Aimin; Cheng, Rongshi

    2012-08-30

    In this current work, the magnetic composite microspheres (MCM), consisting of Fe(3)O(4) nanoparticles and poly(acrylic acid) (PAA) blended chitosan (CS), were prepared successfully by a simple method, co-precipitation of the compounds in alkaline solution. SEM, FTIR and TG techniques have been applied to investigate the structures of the MCM materials. The vibrating-sample magnetometer (VSM) measurement illustrated a paramagnetic property as well as a fast magnetic response, which indicated the significant separability of the MCM in the aqueous suspensions. Then, the MCM materials were employed as absorbents for removal of copper(II) (Cu(II)) ions from aqueous solutions. The fundamental adsorption behaviors of MCM were studied also. Experimental results revealed that the CS/PAA-MCM had greater adsorption capacity than CS-MCM, and PAA played an important role for the adsorption of Cu(II) ions. Moreover, the adsorption isotherms were all well described by the Langmuir model, while the adsorption kinetics followed the pseudo-second order equation. Furthermore, the adsorbent could be easily regenerated at lower pH and reused almost without any loss of adsorption capacity. On the contrary, the Cu(II) ions loaded CS-MCM and CS/PAA-MCM were stable enough at pH higher than 4.0, and both exhibited efficient phosphate removal with maximal uptakes around 63.0 and 108.0 mg Pg(-1), respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. pH effect of coagulation bath on the characteristics of poly(acrylic acid)-grafted and poly(4-vinylpyridine)-grafted poly(vinylidene fluoride) microfiltration membranes.

    PubMed

    Ying, Lei; Zhai, Guangqun; Winata, A Y; Kang, E T; Neoh, K G

    2003-09-15

    The poly(acrylic acid)-graft-poly(vinylidene fluoride) (PAAc-g-PVDF) and poly(4-vinylpyridine)-graft-poly(vinylidene fluoride) (P4VP-g-PVDF) copolymers were obtained by thermally induced molecular graft copolymerization of acrylic acid (AAc) and 4-vinylpyridine (4VP), respectively, with the ozone-pretreated poly(vinylidene fluoride) (PVDF) in N-methyl-2-pyrrolidone (NMP) solution. Microfiltration (MF) membranes were prepared from the respective copolymers by phase inversion in aqueous media. The effects of pH of the coagulation bath on the physicochemical and morphological characteristics of the membranes were investigated. The surface compositions of the membranes were determined by X-ray photoelectron spectroscopy (XPS). The surface graft concentration of the AAc polymer for the PAAc-g-PVDF MF membrane increased with decreasing pH value of the coagulation bath. Completely opposite pH-dependent behavior was observed for the surface graft concentration of the 4VP polymer in the P4VP-g-PVDF MF membranes. A substantial increase in mean pore size was observed for the PAAc-g-PVDF MF membranes cast in basic coagulation baths of increasing pH. In the case of the P4VP-g-PVDF MF membranes, a substantial increase in mean pore size was observed for membranes cast in low pH (acidic) baths. The permeation rate of aqueous solutions through the PAAc-g-PVDF and P4VP-g-PVDF MF membranes exhibited a reversible dependence on the pH of the solution, with the membranes cast near the neutral pH exhibiting the highest sensitivity to changes in permeate pH.

  11. Binding of calcium and carbonate to polyacrylates.

    PubMed

    Tribello, Gareth A; Liew, CheeChin; Parrinello, Michele

    2009-05-21

    Polyacrylate molecules can be used to slow the growth of calcium carbonate. However, little is known about the mechanism by which the molecules impede the growth rate. A recent computational study (Bulo et al. Macromolecules 2007, 40, 3437) used metadynamics to investigate the binding of calcium to polyacrylate chains and has thrown some light on the coiling and precipitation of these polymers. We extend these simulations to examine the binding of calcium and carbonate to polyacrylate chains. We show that calcium complexed with both carbonate and polyacrylate is a very stable species. The free energies of calcium-carbonate-polyacrylate complexes, with different polymer configurations, are calculated, and differences in the free energy of the binding of carbonate are shown to be due to differences in the amount of steric hindrance about the calcium, which prevents the approach of the carbonate ion.

  12. Direct electrochemical oxidation of polyacrylates.

    PubMed

    Bellagamba, Riccardo; Comninellis, Christos; Vatistas, Nicolaos

    2002-10-01

    A promising elimination treatment of non-biodegradable organic pollutants is the direct electro-oxidation. In this work has been proposed the electrochemical elimination of polyacrylates by using boron-doped diamond (BDD) as anodic material. The complete elimination of organic contaminants has been obtained and this is the first case of successful electrochemical treatment of polymeric and bio-refractory species. The tests of the electrochemical oxidation have been conducted at constant current conditions and a complete elimination of organic species has been reached. The decrease of the COD value with time follows the behaviour of an ideal anode as in the case of low molecular organic compounds.

  13. Physically Cross-linked Polymer Binder Induced by Reversible Acid-Base Interaction for High-Performance Silicon Composite Anodes.

    PubMed

    Lim, Sanghyun; Chu, Hodong; Lee, Kukjoo; Yim, Taeeun; Kim, Young-Jun; Mun, Junyoung; Kim, Tae-Hyun

    2015-10-28

    Silicon is greatly promising for high-capacity anode materials in lithium-ion batteries (LIBs) due to their exceptionally high theoretical capacity. However, it has a big challenge of severe volume changes during charge and discharge, resulting in substantial deterioration of the electrode and restricting its practical application. This conflict requires a novel binder system enabling reliable cyclability to hold silicon particles without severe disintegration of the electrode. Here, a physically cross-linked polymer binder induced by reversible acid-base interaction is reported for high performance silicon-anodes. Chemical cross-linking of polymer binders, mainly based on acidic polymers including poly(acrylic acid) (PAA), have been suggested as effective ways to accommodate the volume expansion of Si-based electrodes. Unlike the common chemical cross-linking, which causes a gradual and nonreversible fracturing of the cross-linked network, a physically cross-linked binder based on PAA-PBI (poly(benzimidazole)) efficiently holds the Si particles even after the large volume changes due to its ability to reversibly reconstruct ionic bonds. The PBI-containing binder, PAA-PBI-2, exhibited large capacity (1376.7 mAh g(-1)), high Coulombic efficiency (99.1%) and excellent cyclability (751.0 mAh g(-1) after 100 cycles). This simple yet efficient method is promising to solve the failures relating with pulverization and isolation from the severe volume changes of the Si electrode, and advance the realization of high-capacity LIBs.

  14. Light scattering measurement of sodium polyacrylate products

    NASA Astrophysics Data System (ADS)

    Lama, Nisha; Norwood, David; Boone, Steven; Massie-Boyer, Valerie

    2015-03-01

    In the presentation, we will describe the use of a multi-detector HPLC incorporating the DAWN EOS multi-angle laser light scattering (MALLS) detector to measure the properties such as molecular weight, RMS radius, contour and persistence length and polydispersity of sodium polyacrylate products. The samples of sodium polyacrylate are used in various industries as thickening agents, coating dispersants, artificial snow, laundry detergent and disposable diapers. Data and results obtained from the experiment will be presented.

  15. Injectable biocompatible and biodegradable pH-responsive hollow particle gels containing poly(acrylic acid): the effect of copolymer composition on gel properties.

    PubMed

    Halacheva, Silvia S; Adlam, Daman J; Hendow, Eseelle K; Freemont, Tony J; Hoyland, Judith; Saunders, Brian R

    2014-05-12

    The potential of various pH-responsive alkyl (meth)acrylate ester- and (meth)acrylic acid-based copolymers, including poly(methyl methacrylate-co-acrylic acid) (PMMA-AA) and poly(n-butyl acrylate-co-methacrylic acid) (PBA-MAA), to form pH-sensitive biocompatible and biodegradable hollow particle gel scaffolds for use in non-load-bearing soft tissue regeneration have been explored. The optimal copolymer design criteria for preparation of these materials have been established. Physical gels which are both pH- and redox-sensitive were formed only from PMMA-AA copolymers. MMA is the optimal hydrophobic monomer, whereas the use of various COOH-containing monomers, e.g., MAA and AA, will always induce a pH-triggered physical gelation. The PMMA-AA gels were prepared at physiological pH range from concentrated dispersions of swollen, hollow, polymer-based particles cross-linked with either cystamine (CYS) or 3,3'-dithiodipropionic acid dihydrazide (DTP). A linear relationship between particle swelling ratios, gel elasticity, and ductility was observed. The PMMA-AA gels with lower AA contents feature lower swelling ratios, mechanical strengths, and ductilities. Increasing the swelling ratio (e.g., through increasing AA content) decreased the intraparticle elasticity; however, intershell contact and gel elasticity were found to increase. The mechanical properties and performance of the gels were tuneable upon varying the copolymers' compositions and the structure of the cross-linker. Compared to PMMA-AA/CYS, the PMMA-AA/DTP gels were more elastic and ductile. The biodegradability and cytotoxicity of the new hollow particle gels were tested for the first time and related to their composition, mechanical properties, and morphology. The new PMMA-AA/CYS and PMMA-AA/DTP gels have shown good biocompatibility, biodegradability, strength, and interconnected porosity and therefore have good potential as a tissue repair agent.

  16. Curcumin delivery from poly(acrylic acid-co-methyl methacrylate) hollow microparticles prevents dopamine-induced toxicity in rat brain synaptosomes.

    PubMed

    Yoncheva, Krassimira; Kondeva-Burdina, Magdalena; Tzankova, Virginia; Petrov, Petar; Laouani, Mohamed; Halacheva, Silvia S

    2015-01-01

    The potential of poly(methyl methacrylate-co-acrylic acid) (PMMA-AA) copolymers to form hollow particles and their further formulation as curcumin delivery system have been explored. The particles were functionalized by crosslinking the acrylic acid groups via bis-amide formation with either cystamine (CYS) or 3,3'-dithiodipropionic acid dihydrazide (DTP) which simultaneously incorporated reversibility due to the presence of disulfide bonds within the crosslinker. Optical micrographs showed the formation of spherical hollow microparticles with a size ranging from 1 to 7 μm. Curcumin was loaded by incubation of its ethanol solution with aqueous dispersions of the cross-linked particles and subsequent evaporation of the ethanol. Higher loading was observed in the microparticles with higher content of hydrophobic PMMA units indicating its influence upon the loading of hydrophobic molecules such as curcumin. The in vitro release studies in a phosphate buffer showed no initial burst effect and sustained release of curcumin that correlated with the swelling of the particles under these conditions. The capacity of encapsulated and free curcumin to protect rat brain synaptosomes against dopamine-induced neurotoxicity was examined. The encapsulated curcumin showed greater protective effects in rat brain synaptosomes as measured by synaptosomal viability and increased intracellular levels of glutathione. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. In vivo kinetic analysis of the penicillin biosynthesis pathway using PAA stimulus response experiments.

    PubMed

    Deshmukh, Amit T; Verheijen, Peter J T; Maleki Seifar, Reza; Heijnen, Joseph J; van Gulik, Walter M

    2015-11-01

    In this study we combined experimentation with mathematical modeling to unravel the in vivo kinetic properties of the enzymes and transporters of the penicillin biosynthesis pathway in a high yielding Penicillium chrysogenum strain. The experiment consisted of a step response experiment with the side chain precursor phenyl acetic acid (PAA) in a glucose-limited chemostat. The metabolite data showed that in the absence of PAA all penicillin pathway enzymes were expressed, leading to the production of a significant amount of 6-aminopenicillanic acid (6APA) as end product. After the stepwise perturbation with PAA, the pathway produced PenG within seconds. From the extra- and intracellular metabolite measurements, hypotheses for the secretion mechanisms of penicillin pathway metabolites were derived. A dynamic model of the penicillin biosynthesis pathway was then constructed that included the formation and transport over the cytoplasmic membrane of pathway intermediates, PAA and the product penicillin-G (PenG). The model parameters and changes in the enzyme levels of the penicillin biosynthesis pathway under in vivo conditions were simultaneously estimated using experimental data obtained at three different timescales (seconds, minutes, hours). The model was applied to determine changes in the penicillin pathway enzymes in time, calculate fluxes and analyze the flux control of the pathway. This led to a reassessment of the in vivo behavior of the pathway enzymes and in particular Acyl-CoA:Isopenicillin N Acyltransferase (AT). Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  18. A new inorganic-organic composite coagulant, consisting of polyferric sulphate (PFS) and polyacrylamide (PAA).

    PubMed

    Moussas, P A; Zouboulis, A I

    2009-08-01

    Currently, research is focused on the synthesis of new composite coagulants, which are constituted of both inorganic and organic materials. In this paper, the development of relevant reagents was investigated, by combining the inorganic pre-polymerised iron-based coagulant Polyferric Sulphate (PFS) with an organic, non-ionic polymer (Polyacrylamide, PAA) under different PAA/Fe (mg/l) and OH/Fe molar ratios. Moreover, the new reagents were characterised in terms of typical properties, stability and morphological analysis (XRD, FTIR, SEM). Their coagulation performance, when treating low or high turbid kaolin-humic acid suspensions, was also investigated, whereas the applied coagulation mechanisms were discussed by using the Photometric Dispersion Analysis (PDA) analysis. The results show that the new coagulation reagents present improved properties, including increased effective polymer species concentration, and they exhibit very good stability. The respective tests using PDA confirmed that the predominant coagulation mechanism of PFS-PAA is the bridge formation mechanism. Coagulation experiments in low or high turbid kaolin-humic acid suspensions reveal that the novel composite reagent PFS-PAA exhibits better coagulation performance, when compared with simple PFS, in terms of zeta-potential reduction, turbidity and organic matter removal and residual iron concentration.

  19. Synthesis of interpenetrating network hydrogel from poly(acrylic acid-co-hydroxyethyl methacrylate) and sodium alginate: modeling and kinetics study for removal of synthetic dyes from water.

    PubMed

    Mandal, Bidyadhar; Ray, Samit Kumar

    2013-10-15

    Several interpenetrating network (IPN) hydrogels were made by free radical in situ crosslink copolymerization of acrylic acid (AA) and hydroxy ethyl methacrylate in aqueous solution of sodium alginate. N,N'-methylenebisacrylamide (MBA) was used as comonomer crosslinker for making these crosslink hydrogels. All of these hydrogels were characterized by carboxylic content, FTIR, SEM, XRD, DTA-TGA and mechanical properties. Swelling, diffusion and network parameters of the hydrogels were studied. These hydrogels were used for adsorption of two important synthetic dyes, i.e. Congo red and methyl violet from water. Isotherms, kinetics and thermodynamics of dye adsorption by these hydrogels were also studied.

  20. NGAP: A (Brief) Update PaaS, IaaS, Onbording, and the Future

    NASA Technical Reports Server (NTRS)

    McLaughlin, Brett; Pawloski, Andrew

    2016-01-01

    NASA ESDIS has charged the EED2 program with delivering a NASA-compliant, secure, cloud-based platform for application hosting. More than just a move to the cloud, this has forced us to examine all aspects of application hosting, from resource management to system administration, patching to monitoring, deployment to multiple environments. The result of this mandate is NGAP, the NASA General Application Platform. In this presentation, we will also discuss the various applications we are supporting and targeting, and their architectures including NGAPs move to support both PaaS and IaaS architectures.

  1. Comparison of the toxicity of the peracetic acid formulations Wofasteril(c) E400, E250 and Lspez to Daphnia magna with emphasis on the effect of hydrogen peroxide

    USDA-ARS?s Scientific Manuscript database

    Commercial peracetic acid (PAA) formulations are acidic mixtures of PAA, hydrogen peroxide (H2O2), acetic acid (AA), H2O and stabilizers to maintain equilibrium of the concentrations. Different PAA formulations show diverse PAA/H2O2 ratios, leading to potentially different toxicities at the same con...

  2. Lower critical solution temperature behavior of alpha-substituted poly(acrylic acids)s, cyclopolymerization of N-vinylformamido-methylacrylates, and use of the World-Wide Web in polymer science education

    NASA Astrophysics Data System (ADS)

    Michalovic, Mark Stephen

    A series of alpha-substituted poly(acrylic acid)s was synthesized and characterized. Their aqueous solution properties were investigated with respect to lower critical solution temperature (LCST) behavior. Poly(alpha-methoxymethylacrylic acid) was found to have a lower critical solution temperature (LCST) of 46°C, poly(alpha-methoxyethoxymethylacrylic acid) showed an LCST of 26.5°C and poly(alpha-methoxyethoxyethoxymethylacrylic acid) showed an LCST of 66°C. The cloud points of the solutions of these polymers were found to be sensitive to pH, and to concentrations of additives such as urea, salts, and surfactants. Because of low molecular weight due to chain transfer, high molecular weight analogs of the ether-linked polymers were synthesized in which ester linkages joined the oligo-oxyethylene segment to the acrylate moiety. Poly(alpha-methoxyethoxyacetoxymethylacrylic acid) was the only one of this series to give an LCST with a value of 52.5°C. Copolymers of t-butyl alpha-methoxymethylacrylate (tBMMA) with alpha-(1H,1H- perfluorooctyloxymethyl)acrylic acid (PFOMA) were synthesized, deprotected and their lower critical solution temperatures (LCSTs) evaluated. At PFOMA feed ratios of 0.25 mol % or less, no observable change in the LCST was observed, while at PFOMA feed ratios of above 0.25 mol % to 1.125 mol %, a large linear decrease in the LCST was observed with increasing fluorocarbon content. t-Butyl alpha-(N-vinylformamidomethyl)acrylate (tBVFA) and ethyl alpha-(N-vinylformamidomethyl)acrylate (EVFA) were synthesized from t-butyl alpha-bromomethylacrylate and ethyl alpha-chloromethylacrylate, respectively. tBVFA was found to cyclopolymerize at 120°C in DMF, DMSO, and 1,2-dichlorobenzene at solvent:monomer ratios of 10:1 vol:wt. Molecular weights for poly(tBVFA) ranged from 10,000 to 13,000 as estimated by size-exclusion chromatography. At lower solvent monomer ratio (1:1), and at lower temperature (71°C), crosslinking occurred. EVFA was found to

  3. Influence of the degree of neutralization of acrylic acid and cross-linking agent on optical properties and swelling of sodium polyacrylate

    NASA Astrophysics Data System (ADS)

    Gredyukhina, I. V.; Plotnikova, L. V.; Balbekin, N. S.; Kulya, M. S.; Petrov, N. V.; Nechiporenko, A. P.; Uspenskaya, M. V.

    2017-06-01

    Optical characteristics of polymerization products under variable degrees of neutralization of acrylic acid (AA) and cross-linking agent and at a fixed content of redox components have been studied by IR spectroscopy of frustrated total internal reflection and THz spectroscopy. The results of the analysis show that absorption of IR radiation and dispersion of THz radiation for the samples under study depend on the degree of AA neutralization, which predetermines the mechanism of structure formation of hydrogels, refractive index, and degree of their limited swelling. It is found that the dependences of the refractive index of dry compact hydrogels and the degree of limited swelling of ground polymer samples on the content of neutralizing agent in solutions of the reaction systems have a symbatic character.

  4. Pulse versus continuous peracetic acid applications: effects on Rainbow trout performance, biofilm formation and water quality

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) products are being introduced to aquaculture as sustainable disinfectants. Two strategies are used to apply PAA: short term high dose (1-2 mg L-1 PAA) periodic pulse applications or continuous low dose (< 0.2 mg L-1 PAA) applications. In the present study, these strategies and a...

  5. Poly(acrylic acid)-regulated Synthesis of Rod-Like Calcium Carbonate Nanoparticles for Inducing the Osteogenic Differentiation of MC3T3-E1 Cells.

    PubMed

    Yang, Wei; Yao, Chenxue; Cui, Zhengyang; Luo, Dandan; Lee, In-Seop; Yao, Juming; Chen, Cen; Kong, Xiangdong

    2016-05-06

    Calcium carbonate, especially with nanostructure, has been considered as a good candidate material for bone regeneration due to its excellent biodegradability and osteoconductivity. In this study, rod-like calcium carbonate nanoparticles (Rod-CC NPs) with desired water dispersibility were achieved with the regulation of poly (acrylic acid). Characterization results revealed that the Rod-CC NPs had an average length of 240 nm, a width of 90 nm with an average aspect ratio of 2.60 and a negative ζ-potential of -22.25 ± 0.35 mV. The degradation study illustrated the nanoparticles degraded 23% at pH 7.4 and 45% at pH 5.6 in phosphate-buffered saline (PBS) solution within three months. When cultured with MC3T3-E1 cells, the Rod-CC NPs exhibited a positive effect on the proliferation of osteoblast cells. Alkaline phosphatase (ALP) activity assays together with the osteocalcin (OCN) and bone sialoprotein (BSP) expression observations demonstrated the nanoparticles could induce the differentiation of MC3T3-E1 cells. Our study developed well-dispersed rod-like calcium carbonate nanoparticles which have great potential to be used in bone regeneration.

  6. Poly(acrylic acid)-regulated Synthesis of Rod-Like Calcium Carbonate Nanoparticles for Inducing the Osteogenic Differentiation of MC3T3-E1 Cells

    PubMed Central

    Yang, Wei; Yao, Chenxue; Cui, Zhengyang; Luo, Dandan; Lee, In-Seop; Yao, Juming; Chen, Cen; Kong, Xiangdong

    2016-01-01

    Calcium carbonate, especially with nanostructure, has been considered as a good candidate material for bone regeneration due to its excellent biodegradability and osteoconductivity. In this study, rod-like calcium carbonate nanoparticles (Rod-CC NPs) with desired water dispersibility were achieved with the regulation of poly (acrylic acid). Characterization results revealed that the Rod-CC NPs had an average length of 240 nm, a width of 90 nm with an average aspect ratio of 2.60 and a negative ζ-potential of −22.25 ± 0.35 mV. The degradation study illustrated the nanoparticles degraded 23% at pH 7.4 and 45% at pH 5.6 in phosphate-buffered saline (PBS) solution within three months. When cultured with MC3T3-E1 cells, the Rod-CC NPs exhibited a positive effect on the proliferation of osteoblast cells. Alkaline phosphatase (ALP) activity assays together with the osteocalcin (OCN) and bone sialoprotein (BSP) expression observations demonstrated the nanoparticles could induce the differentiation of MC3T3-E1 cells. Our study developed well-dispersed rod-like calcium carbonate nanoparticles which have great potential to be used in bone regeneration. PMID:27164090

  7. Preparation of a reticulated polyurethane foam grafted with poly(acrylic acid) through atmospheric pressure plasma treatment and its lysozyme immobilization.

    PubMed

    Myung, Sung-Woon; Yeom, Young-Ho; Jang, Young-Mi; Choi, Ho-Suk; Cho, Daechul

    2005-08-01

    We successfully introduced peroxide groups onto the surface of PU(Polyurethane) foam(10 PPI) through one atmospheric pressure plasma treatment and sequentially grafted PAAc(poly(acrylic acid)) on the surface of PU through radical copolymerization. The plasma treatment can generate large amount of peroxides on the surface of PU foam and the peroxide groups act as initiators for further grafting of PAAc in the monomer solution. To introduce large amount of peroxides on the surface of PU foam, we studied the effect of plasma rf-power and treatment time on the maximum grafting of PAAc. Through this study, we found that the optimum plasma treatment condition was the rf-power of 100 W and the treatment time of 100 s. On the other hand, we also studied the effect of graft reaction conditions such as temperature, monomer concentration and reaction time on the change of grafting degree (GD). The GD increased with increasing temperature and increased with reaction time before it leveled off at 3 h after reaction started. At low concentration of AAc, the GD was very low but it showed a maximum at the monomer concentration between 60 and 70%. The surface of the modified PU foam was qualitatively and quantitatively analyzed through the use of FT-IR and weight measurement, respectively. We also observed the surface change before and after plasma induced graft co-polymerization through photo and SEM analysis. Finally, we confirmed that the PU foams grafted with PAAc successfully immobilized lysozyme and other proteins from hen egg white.

  8. Alpha-tricalcium phosphate hydrolysis to octacalcium phosphate: effect of sodium polyacrylate.

    PubMed

    Bigi, A; Boanini, E; Botter, R; Panzavolta, S; Rubini, K

    2002-04-01

    Alpha-Tricalcium phosphate (alpha-TCP) hydrolysis into octacalcium phosphate (OCP) has been investigated in phosphoric acid solution at different concentrations of sodium polyacrylate (NaPA). The hydrolysis process has been followed by powder X-ray diffraction, infrared absorption and scanning electron microscopy analyses. In the absence of the polyelectrolyte, alpha-TCP undergoes a complete transformation into OCP in 24 h. The presence of polyacrylate in solution inhibits the hydrolysis so that a NaPA concentration of 0.5 microm is sufficient to lengthen the time required to complete the hydrolysis to 4 days. The variation of Ca2+ concentration in the soaking solution suggests that the transformation occurs through alpha-TCP dissolution followed by OCP precipitation. The delayed OCP nucleation and growth in the presence of polyacrylate implies a preferential adsorption of the polyelectrolyte on the growing OCP crystals, which induces an anisotropic reduction of the coherence lengths of the perfect crystalline domains.

  9. Rheological and sensory properties of hydrophilic skin protection gels based on polyacrylates.

    PubMed

    Kulawik-Pióro, Agnieszka; Kurpiewska, Joanna; Kułaszka, Agnieszka

    2017-04-10

    With the current increases in occupational skin diseases, literature data attesting the decreasing efficiency of barrier creams with respect to the manufacturer's declarations and legal regulations granting skin protection gels for employees, research is required to analyse and evaluate the recipes used for hydrophilic skin protection gels based on polyacrylates. This study investigated the rheological properties, pH and sensory perception of hydrophilic barrier gels based on polyacrylates. The acrylic acid derivatives used were good thickeners, and helped to form transparent gels of adequate durability. They could be used to create hydrophilic films on the surface of the skin to protect it against hydrophobic substances. A correlation was shown between the results of the rheological properties and the barrier properties of the gels. This confirms the possibility of monitoring the quality of the gels at the stage of recipe development. Polyacrylates are viable for use in industry to produce hydrophilic barrier creams suitable for skin protection.

  10. Adsorption of organic diacids and sodium polyacrylate onto montmorillonite

    SciTech Connect

    Siffert, B.; Espinasse, P.

    1980-01-01

    Organic diacid (oxalic and succinic) adsorption onto montmorillonite is feasible, but weak. The comparison of chemical and radiochemical determinations reveals that 80% of the acid in contact with the smectite is used to attach the clay lattice. The pH is the main parameter involved in adsorption, and fixation passes through a minimum for pH 6 to 7. Polyacrylate adsorption also is weak. It changes with the nature of the exchangeable cation of smectite. Its pH dependence displays a pronounced maximum for a value corresponding to the pKa of the acidic functions (pH = approx. = 6.8), and a minimum at approximately pH 8. On the assumption that a polyacrylate macromolecule is 100% hydrolyzed, it follows that the -COOH groups carried by 20% hydrolyzed polyacrylamide molecules (such as those used in the tertiary recovery of petroleum) contribute at the very most to 10% of the total adsorption onto clay. Therefore, fixation involves predominantly protonation of the amide functions at the edge surfaces of the clay. The acidic functions play a minor role in the adsorption phenomenon in that they affect the length of the macromolecule. However, the extent of this contribution is virtually impossible to estimate. 17 references.

  11. “Stable-on-the-Table” Biosensors: Hemoglobin-Poly (Acrylic Acid) Nanogel BioElectrodes with High Thermal Stability and Enhanced Electroactivity

    PubMed Central

    Ghimire, Ananta; Zore, Omkar V.; Thilakarathne, Vindya K.; Briand, Victoria A.; Lenehan, Patrick J.; Lei, Yu; Kasi, Rajeswari M.; Kumar, Challa V.

    2015-01-01

    In our efforts toward producing environmentally responsible but highly stable bioelectrodes with high electroactivities, we report here a simple, inexpensive, autoclavable high sensitivity biosensor based on enzyme-polymer nanogels. Met-hemoglobin (Hb) is stabilized by wrapping it in high molecular weight poly(acrylic acid) (PAA, MW 450k), and the resulting nanogels abbreviated as Hb-PAA-450k, withstood exposure to high temperatures for extended periods under steam sterilization conditions (122 °C, 10 min, 17–20 psi) without loss of Hb structure or its peroxidase-like activities. The bioelectrodes prepared by coating Hb-PAA-450k nanogels on glassy carbon showed well-defined quasi-reversible redox peaks at −0.279 and −0.334 V in cyclic voltammetry (CV) and retained >95% electroactivity after storing for 14 days at room temperature. Similarly, the bioelectrode showed ~90% retention in electrochemical properties after autoclaving under steam sterilization conditions. The ultra stable bioelectrode was used to detect hydrogen peroxide and demonstrated an excellent detection limit of 0.5 μM, the best among the Hb-based electrochemical biosensors. This is the first electrochemical demonstration of steam-sterilizable, storable, modular bioelectrode that undergoes reversible-thermal denaturation and retains electroactivity for protein based electrochemical applications. PMID:26393601

  12. "Stable-on-the-Table" Biosensors: Hemoglobin-Poly (Acrylic Acid) Nanogel BioElectrodes with High Thermal Stability and Enhanced Electroactivity.

    PubMed

    Ghimire, Ananta; Zore, Omkar V; Thilakarathne, Vindya K; Briand, Victoria A; Lenehan, Patrick J; Lei, Yu; Kasi, Rajeswari M; Kumar, Challa V

    2015-09-18

    In our efforts toward producing environmentally responsible but highly stable bioelectrodes with high electroactivities, we report here a simple, inexpensive, autoclavable high sensitivity biosensor based on enzyme-polymer nanogels. Met-hemoglobin (Hb) is stabilized by wrapping it in high molecular weight poly(acrylic acid) (PAA, M(W) 450k), and the resulting nanogels abbreviated as Hb-PAA-450k, withstood exposure to high temperatures for extended periods under steam sterilization conditions (122 °C, 10 min, 17-20 psi) without loss of Hb structure or its peroxidase-like activities. The bioelectrodes prepared by coating Hb-PAA-450k nanogels on glassy carbon showed well-defined quasi-reversible redox peaks at -0.279 and -0.334 V in cyclic voltammetry (CV) and retained >95% electroactivity after storing for 14 days at room temperature. Similarly, the bioelectrode showed ~90% retention in electrochemical properties after autoclaving under steam sterilization conditions. The ultra stable bioelectrode was used to detect hydrogen peroxide and demonstrated an excellent detection limit of 0.5 μM, the best among the Hb-based electrochemical biosensors. This is the first electrochemical demonstration of steam-sterilizable, storable, modular bioelectrode that undergoes reversible-thermal denaturation and retains electroactivity for protein based electrochemical applications.

  13. 21 CFR 173.73 - Sodium polyacrylate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium polyacrylate. 173.73 Section 173.73 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Polymer Substances and Polymer Adjuvants...

  14. Hygienisierung in der Fischzucht mittels Per-essigsäure (Disinfection of water with PAA: State of the investigations)

    USDA-ARS?s Scientific Manuscript database

    There are very few therapeutic agents against aquaculture ectoparasites in Germany. Peracetic Acid (PAA) has been referred to as the best disinfective agent in the world, but it has not been used much here in aquaculture. We currently use this compound in ‘treatment crisis’ situations because ther...

  15. Induced polymersome formation from a diblock PS-b-PAA polymer via encapsulation of positively charged proteins and peptides.

    PubMed

    Hvasanov, David; Wiedenmann, Jörg; Braet, Filip; Thordarson, Pall

    2011-06-14

    In contrast to simple salts or negatively charged macromolecules, positively charged proteins and peptides including cytochrome c (yeast) and poly-L-lysine are efficiently encapsulated while inducing the formation of polymersomes from polystyrene(140)-b-poly(acrylic acid)(48) (PS(140)-b-PAA(48)). This journal is © The Royal Society of Chemistry 2011

  16. Intestinal Targeting of Ganciclovir Release Employing a Novel HEC-PAA Blended Lyomatrix.

    PubMed

    Mabrouk, Mostafa; Mulla, Jameel A S; Kumar, Pradeep; Chejara, Dharmesh R; Badhe, Ravindra V; Choonara, Yahya E; du Toit, Lisa C; Pillay, Viness

    2016-10-01

    A hydroxyethylcellulose-poly(acrylic acid) (HEC-PAA) lyomatrix was developed for ganciclovir (GCV) intestine targeting to overcome its undesirable degradation in the stomach. GCV was encapsulated within the HEC-PAA lyomatrix prepared by lyophilization. Conventional tablets were also prepared with identical GCV concentrations in order to compare the GCV release behavior from the lyomatrix and tablets. GCV incorporation (75.12%) was confirmed using FTIR, DSC, and TGA. The effect of GCV loading on the microstructure properties of the lyomatrix was evaluated by SEM, AFM, and BET surface area measurements. The in vitro drug release study showed steady and rapid release profiles from the GCV-loaded lyomatrix compared with the tablet formulation at identical pH values. Minimum GCV release was observed at acidic pH (≤40%) and maximum release occurred at intestinal pH values (≥90%) proving the intestinal targeting ability of the lyomatrix. Kinetic modeling revealed that the GCV-loaded lyomatrix exhibited zero-order release kinetics (n = 1), while the tablets were best described via the Peppas model. Textural analysis highlighted enhanced matrix resilience and rigidity gradient (12.5%, 20 Pa) for the GCV-loaded lyomatrix compared to the pure (7%, 9.5 Pa) HEC-PAA lyomatrix. Bench-top MRI imaging was used to confirm the mechanism of GCV release behavior by monitoring the swelling and erosion rates. The swelling and erosion rate of the tablets was not sufficient to achieve rapid zero-order GCV release as with the lyomatrix. These combined results suggest that the HEC-PAA lyomatrix may be suitable for GCV intestinal targeting after oral administration.

  17. Electrochemical lithiation performance and characterization of silicon-graphite composites with lithium, sodium, potassium, and ammonium polyacrylate binders.

    PubMed

    Han, Zhen-Ji; Yamagiwa, Kiyofumi; Yabuuchi, Naoaki; Son, Jin-Young; Cui, Yi-Tao; Oji, Hiroshi; Kogure, Akinori; Harada, Takahiro; Ishikawa, Sumihisa; Aoki, Yasuhito; Komaba, Shinichi

    2015-02-07

    Poly(acrylic acid) (PAH), which is a water soluble polycarboxylic acid, is neutralized by adding different amounts of LiOH, NaOH, KOH, and ammonia (NH4OH) aqueous solutions to fix neutralization degrees. The differently neutralized polyacid, alkali and ammonium polyacrylates are examined as polymeric binders for the preparation of Si-graphite composite electrodes as negative electrodes for Li-ion batteries. The electrode performance of the Si-graphite composite depends on the alkali chemicals and neutralization degree. It is found that 80% NaOH-neutralized polyacrylate binder (a pH value of the resultant aqueous solution is ca. 6.7) is the most efficient binder to enhance the electrochemical lithiation and de-lithiation performance of the Si-graphite composite electrode compared to that of conventional PVdF and the other binders used in this study. The optimum polyacrylate binder highly improves the dispersion of active material in the composite electrode. The binder also provides the strong adhesion, suitable porosity, and hardness for the composite electrode with 10% (m/m) binder content, resulting in better electrochemical reversibility. From these results, the factors of alkali-neutralized polyacrylate binders affecting the electrode performance of Si-graphite composite electrodes are discussed.

  18. Superabsorbent hydrogels via graft polymerization of acrylic acid from chitosan-cellulose hybrid and their potential in controlled release of soil nutrients.

    PubMed

    Essawy, Hisham A; Ghazy, Mohamed B M; El-Hai, Farag Abd; Mohamed, Magdy F

    2016-08-01

    Superabsorbent polymers fabricated via grafting polymerization of acrylic acid from chitosan (CTS) yields materials that suffer from poor mechanical strength. Hybridization of chitosan with cellulose (Cell) via chemical bonding using thiourea formaldehyde resin increases the flexibility of the produced hybrid (CTS/Cell). The hybridization process and post graft polymerization of acrylic acid was followed using Fourier transform infrared (FTIR). Also, the obtained structures were homogeneous and exhibited uniform surface as could be shown from imaging with scanning electron microscopy (SEM). Thus, the polymers derived from the grafting of polyacrylic acid from (CTS/Cell) gave rise to much more mechanically robust structures ((CTS/Cell)-g-PAA) that bear wide range of pH response due to presence of chitosan and polyacrylic acid in one homogeneous entity. Additionally, the obtained structures possessed greater water absorbency 390, 39.5g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced retention potential even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high grafting efficiency (GE%), 86.4%, and grafting yield (GY%), 750%. The new superabsorbent polymers proved to be very efficient devices for controlled release of fertilizers into the soil which expands their use in agriculture and horticultural applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Humic acid metal cation interaction studied by spectromicroscopy techniques in combination with quantum chemical calculations.

    PubMed

    Plaschke, M; Rothe, J; Armbruster, M K; Denecke, M A; Naber, A; Geckeis, H

    2010-03-01

    Humic acids (HA) have a high binding capacity towards traces of toxic metal cations, thus affecting their transport in aquatic systems. Eu(III)-HA aggregates are studied by synchrotron-based scanning transmission X-ray microscopy (STXM) at the carbon K-edge and laser scanning luminescence microscopy (LSLM) at the (5)D(0) --> (7)F(1,2) fluorescence emission lines. Both methods provide the necessary spatial resolution in the sub-micrometre range to resolve characteristic aggregate morphologies: optically dense zones embedded in a matrix of less dense material in STXM images correspond to areas with increased Eu(III) luminescence yield in the LSLM micrographs. In the C 1s-NEXAFS of metal-loaded polyacrylic acid (PAA), used as a HA model compound, a distinct complexation effect is identified. This effect is similar to trends observed in the dense fraction of HA/metal cation aggregates. The strongest complexation effect is observed for the Zr(IV)-HA/PAA system. This effect is confirmed by quantum chemical calculations performed at the ab initio level for model complexes with different metal centres and complex geometries. Without the high spatial resolution of STXM and LSLM and without the combination of molecular modelling with experimental results, the different zones indicating a ;pseudo'-phase separation into strong complexing domains and weaker complexing domains of HA would never have been identified. This type of strategy can be used to study metal interaction with other organic material.

  20. Humic Acid Metal Cation Interaction Studied by Spectromicroscopy Techniques in Combination with Quantum Chemical Calculations

    SciTech Connect

    Plaschke, M.; Rothe, J; Armbruster, M; Denecke, M; Naber, A; Geckeis, H

    2010-01-01

    Humic acids (HA) have a high binding capacity towards traces of toxic metal cations, thus affecting their transport in aquatic systems. Eu(III)-HA aggregates are studied by synchrotron-based scanning transmission X-ray microscopy (STXM) at the carbon K-edge and laser scanning luminescence microscopy (LSLM) at the {sup 5}D{sub 0} {yields} {sup 7}F{sub 1,2} fluorescence emission lines. Both methods provide the necessary spatial resolution in the sub-micrometre range to resolve characteristic aggregate morphologies: optically dense zones embedded in a matrix of less dense material in STXM images correspond to areas with increased Eu(III) luminescence yield in the LSLM micrographs. In the C 1s-NEXAFS of metal-loaded polyacrylic acid (PAA), used as a HA model compound, a distinct complexation effect is identified. This effect is similar to trends observed in the dense fraction of HA/metal cation aggregates. The strongest complexation effect is observed for the Zr(IV)-HA/PAA system. This effect is confirmed by quantum chemical calculations performed at the ab initio level for model complexes with different metal centres and complex geometries. Without the high spatial resolution of STXM and LSLM and without the combination of molecular modelling with experimental results, the different zones indicating a 'pseudo'-phase separation into strong complexing domains and weaker complexing domains of HA would never have been identified. This type of strategy can be used to study metal interaction with other organic material.

  1. Rheological characterization of cataplasm bases composed of cross-linked partially neutralized polyacrylate hydrogel.

    PubMed

    Wang, Jian; Zhang, Hongqin; An, Dianyun; Yu, Jian; Li, Wei; Shen, Teng; Wang, Jianxin

    2014-10-01

    Viscoelasticity is a useful parameter for characterizing the intrinsic properties of the cross-linked polyacrylate hydrogel used in cataplasm bases. The aim of this study was to investigate the effects of various formulation parameters on the rheological characteristics of polyacrylate hydrogel. The hydrogel layers were formed using a partially neutralized polyacrylate (Viscomate(™)), which contained acrylic acid and sodium acrylate in different copolymerization ratios, as the cross-linked gel framework. Dihydroxyaluminum aminoacetate (DAAA), which produces aluminum ions, was used as the cross-linking agent. Rheological analyses were performed using a "stress amplitude sweep" and a "frequency sweep". The results showed that greater amounts of acrylic acid in the structure of Viscomate as well as higher concentrations of DAAA and Viscomate led to an increase in the elastic modulus (G'). However, greater amounts of acrylic acid in the structure of Viscomate and higher concentrations of DAAA had an opposite on the viscous modulus (G″); this might be owing to higher steric hindrance. The results of this study can serve as guidelines for the optimization of formulations for cataplasms.

  2. Wastewater disinfection by peracetic acid: assessment of models for tracking residual measurements and inactivation.

    PubMed

    Santoro, Domenico; Gehr, Ronald; Bartrand, Timothy A; Liberti, Lorenzo; Notarnicola, Michele; Dell'Erba, Adele; Falsanisi, Dario; Haas, Charles N

    2007-07-01

    With its potential for low (if any) disinfection byproduct formation and easy retrofit for chlorine contactors, peracetic acid (PAA) or use of PAA in combination with other disinfectant technologies may be an attractive alternative to chlorine-based disinfection. Examples of systems that might benefit from use of PAA are water reuse schemes or plants discharging to sensitive receiving water bodies. Though PAA is in use in numerous wastewater treatment plants in Europe, its chemical kinetics, microbial inactivation rates, and mode of action against microorganisms are not thoroughly understood. This paper presents results from experimental studies of PAA demand, PAA decay, and microbial inactivation, with a complementary modeling analysis. Model results are used to evaluate techniques for measurement of PAA concentration and to develop hypotheses regarding the mode of action of PAA in bacterial inactivation. Kinetic and microbial inactivation rate data were collected for typical wastewaters and may be useful for engineers in evaluating whether to convert from chlorine to PAA disinfection.

  3. Industrial solution contaminated by polyacrylates: their elimination by electrochemical combustion.

    PubMed

    Masci, M; Chiti, L; De Lorenzo, A; Mantione, D; De Battisti, A; Vatistas, N

    2001-01-01

    The electrochemical combustion of polyacrylates was studied through both direct and indirect oxidation. The obtained results indicate the non elimination of the polyacrylates with the direct oxidation, while the indirect oxidation with NaCl completely eliminates these organic compounds. In the last case the effects of different initial concentrations of NaCl, anode materials and current densities was studied.

  4. Polyacrylate membranes for tunable liquid-filled microlenses

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Zappe, Hans; Seifert, Andreas

    2013-04-01

    We present the use of polyacrylate membranes for the fabrication of pneumatically actuated variable lenses. Whereas the most commonly used membrane material for tunable liquid-filled lenses is polydimethylsiloxane (PDMS), polyacrylate membranes have the advantages of high resistance to swelling in silicone oil and enhanced compatibility with a wide range of aqueous optical liquids. These features are quantitatively demonstrated by comparing the material properties and performance of PDMS and polyacrylate membrane lenses. The optical transparency of polyacrylate is more than 92%. The surface roughness is below 3.3 nm rms, and reversible elastic deformation could be demonstrated. Optical measurements show that the cutoff frequency of the modulation transfer function of polyacrylate lenses with different liquid fillings, using a reference contrast of 0.2, is more than 1.5 times larger than that of the same system assembled with PDMS membranes filled with water.

  5. Nacre-inspired integrated strong and tough reduced graphene oxide-poly(acrylic acid) nanocomposites

    NASA Astrophysics Data System (ADS)

    Wan, Sijie; Hu, Han; Peng, Jingsong; Li, Yuchen; Fan, Yuzun; Jiang, Lei; Cheng, Qunfeng

    2016-03-01

    Inspired by the relationship between interface interactions and the high performance mechanical properties of nacre, a strong and tough nacre-inspired nanocomposite was demonstrated based on graphene oxide (GO) and polyacrylic acid (PAA) prepared via a vacuum-assisted filtration self-assembly process. The abundant hydrogen bonding between GO and PAA results in both high strength and toughness of the bioinspired nanocomposites, which are 2 and 3.3 times higher than that of pure reduced GO film, respectively. In addition, the effect of environmental relative humidity on the mechanical properties of bioinspired nanocomposites is also investigated, and is consistent with previous theoretical predictions. Moreover, this nacre-inspired nanocomposite also displays high electrical conductivity of 108.9 S cm-1. These excellent physical properties allow this type of nacre-inspired nanocomposite to be used in many applications, such as flexible electrodes, aerospace applications, and artificial muscles etc. This nacre-inspired strategy also opens an avenue for constructing integrated high performance graphene-based nanocomposites in the near future.

  6. Nacre-inspired integrated strong and tough reduced graphene oxide-poly(acrylic acid) nanocomposites.

    PubMed

    Wan, Sijie; Hu, Han; Peng, Jingsong; Li, Yuchen; Fan, Yuzun; Jiang, Lei; Cheng, Qunfeng

    2016-03-14

    Inspired by the relationship between interface interactions and the high performance mechanical properties of nacre, a strong and tough nacre-inspired nanocomposite was demonstrated based on graphene oxide (GO) and polyacrylic acid (PAA) prepared via a vacuum-assisted filtration self-assembly process. The abundant hydrogen bonding between GO and PAA results in both high strength and toughness of the bioinspired nanocomposites, which are 2 and 3.3 times higher than that of pure reduced GO film, respectively. In addition, the effect of environmental relative humidity on the mechanical properties of bioinspired nanocomposites is also investigated, and is consistent with previous theoretical predictions. Moreover, this nacre-inspired nanocomposite also displays high electrical conductivity of 108.9 S cm(-1). These excellent physical properties allow this type of nacre-inspired nanocomposite to be used in many applications, such as flexible electrodes, aerospace applications, and artificial muscles etc. This nacre-inspired strategy also opens an avenue for constructing integrated high performance graphene-based nanocomposites in the near future.

  7. [Studies on primary aromatic amines (PAAs) migration from multi-layer plastic food packaging by HPLC method].

    PubMed

    Cwiek-Ludwicka, Kazimiera; Pawlicka, Marzena; Starski, Andrzej; Półtorak, Hanna; Karłowski, Kazimierz

    2011-01-01

    The aim of this study was to identify of primary aromatic amines (PAAs) and to determine their migration from plastic food packaging. The magnitude of the migration of these substances from plastic food packaging consists a base for the evaluation of their compliance with the requirements of EU legislation and hazard for human health taking into account their migration into food. The unprinted and printed multi-layer plastic packaging (laminates), domestic and imported, were examined in these studies. PAAs migration tests from the laminates into food simulant (3% acetic acid) was performed according to the appropriate procedures recommended in the EU for testing migration from food contact articles under standard conditions reflecting the real use of laminates (10 days, 40 degrees C) and under ,, worst case scenario" conditions (2 h, 70 degrees C). PAAs present in migration solutions were concentrated on SPE columns and then seven PAAs (aniline, 1,3-phenylenediamine, 2, 6-toluenediamine, 2,4-toluenediamine, 4,4'-oxydianiline, 4,4'-methylenedianiline and 3,3 '-dimethylbenzidyne) were identified and determined by previously validated HPLC-DAD method. Depending on the migration conditions the PAAs content was different. When the "worst case scenario" conditions were applied the migration of 4,4 '-methylenedianiline (4,4 '-MDA) ranged from below detection limit (LOD = 0.51 microg/kg) up to 9.86 microg/kg, and aniline was released in the range from below detection limit (LOD = 0,98 microg/kg) up to 7.04 microg/kg. In two laminate samples of eight examined, the sum of PAAs (aniline and 4,4'-MDA) was 13.32 microg/kg and 14.72 microg/kg showing that the permitted limit (10 microg/kg) was exceeded. In the standard conditions, the migration of aniline and 4,4'-MDA was significantly lower Regarding the carcinogenic potential of PAAs, the laminates causing the amines migration above the permitted limit should not be used as food packaging.

  8. Acute toxicity of peracetic acid to fish

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA; also called peroxyacetic acid) is a stabilized mixture of acetic acid, hydrogen peroxide and water that does not leave dangerous residues in the environment when it breaks down as most compounds do. PAA is a promising disinfectant in the US aquaculture industry to control paras...

  9. Functionalized graphene and graphene oxide solution via polyacrylate coating.

    PubMed

    Saha, Arindam; Basiruddin, S K; Ray, S C; Roy, S S; Jana, Nikhil R

    2010-12-01

    Water soluble graphene with various chemical- and biofunctionalities is essential for their different applications. However, exfoliated graphenes are insoluble in water and water soluble graphene oxide precipitate if they are chemically reduced to graphene. We have developed a polyacrylate coating method for graphene oxide and then chemically reduced it into graphene. We found that polyacrylate coating can improve the colloidal stability of both graphene and graphene oxide. The coated graphene has been characterized using XPS, FTIR, XRD and micro-Raman spectroscopy. The primary amine present on the coating backbone has been used to derive glucose functionalized water soluble graphene. Various other functional graphenes can be anticipated from the polyacrylate coated graphene.

  10. Graphene oxide/poly(acrylic acid)/gelatin nanocomposite hydrogel: experimental and numerical validation of hyperelastic model.

    PubMed

    Faghihi, Shahab; Karimi, Alireza; Jamadi, Mahsa; Imani, Rana; Salarian, Reza

    2014-05-01

    Owing to excellent thermal and mechanical properties, graphene-based nanomaterials have recently attracted intensive attention for a wide range of applications, including biosensors, bioseparation, drug release vehicle, and tissue engineering. In this study, the effects of graphene oxide nanosheet (GONS) content on the linear (tensile strength and strain) and nonlinear (hyperelastic coefficients) mechanical properties of poly(acrylic acid) (PAA)/gelatin (Gel) hydrogels are evaluated. The GONS with different content (0.1, 0.3, and 0.5 wt.%) is added into the prepared PAA/Gel hydrogels and composite hydrogels are subjected to a series of tensile and stress relaxation tests. Hyperelastic strain energy density functions (SEDFs) are calibrated using uniaxial experimental data. The potential ability of different hyperelastic constitutive equations (Neo-Hookean, Yeoh, and Mooney-Rivlin) to define the nonlinear mechanical behavior of hydrogels is verified by finite element (FE) simulations. The results show that the tensile strength (71%) and elongation at break (26%) of composite hydrogels are significantly increased by the addition of GONS (0.3 wt.%). The experimental data is well fitted with those predicted by the FE models. The Yeoh material model accurately defines the nonlinear behavior of hydrogels which can be used for further biomechanical simulations of hydrogels. This finding might have implications not only for the improvement of the mechanical properties of composite hydrogels but also for the fabrication of polymeric substrate materials suitable for tissue engineering applications.

  11. Growth inhibition of Aeromonas salmonicida and Yersinia ruckeri by disinfectants containing peracetic acid

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) is an agent used for disinfection in aquaculture. PAA contributes to sustainable aquaculture, because it releases no harmful residue in the environment. However, there is lack of guideline about the effective application of different PAA products against various pathogens in p...

  12. Imaging and Chemotherapeutic Comparisons of Iron Oxide Nanoparticles Chemically and Physically Coated with Poly(ethylene glycol)-b-Poly(ε-caprolactone)-g-Poly(acrylic acid).

    PubMed

    Chen, Guo-Jing; Hsu, Chin; Ke, Jyun-Han; Wang, Li-Fang

    2015-06-01

    We designed a new copolymer, poly(ethylene glycol)-block-poly(ε-caprolactone)-graft-poly(acrylic acid) (PAA-PEC), which could be chemically and physically coated onto iron oxide (Fe3O4) nanoparticles for theranostic applications. The chemically PAA-PEC-coated Fe3O4 nanoparticles (PAA-PEC-IO) were prepared using the carboxylic groups of PAA-PEC to bind the Fe3O4 nanoparticles during a co-precipitation reaction. Because of the amphiphilic properties of PAA-PEC, the compound self-assembled into a core-shell structure. The hydrophobic oleic acid-coated Fe3O4 nanoparticles could then be physically encapsulated inside the hydrophobic core of PAA-PEC (PAA-PEC-OA-IO) using an emulsion technique. A similar amount of iron content was controlled in both the PAA-PEC-IO and PAA-PEC-OA-IO (-23%). The particle diameters, morphologies, superparamagnetism, drug loading efficiency, and transversal relaxivity (r2) were studied and compared between the two magnetic nanoparticles. All results displayed the chemically-synthesized PAA-PEC-IO nanoparticles had higher potential than did the physically-synthesized PAA-PEC-OA-IO as an MRI contrast agent and a drug delivery carrier. Rodamine123-linked PAA-PEC-IO (PAA-PEC-IO-Rh123) was used as a molecular probe. Flow cytometric diagrams indicated that cellular internalization of PAA-PEC-IO occurred primarily through clathrin-mediated endocytosis.

  13. Polyaspartate scale inhibitors -- Biodegradable alternatives to polyacrylates

    SciTech Connect

    Ross, R.J.; Low, K.C.; Shannon, J.E.

    1996-12-01

    Polyaspartates are highly biodegradable alternatives to polyacrylate based scale inhibitors. This paper presents laboratory testing data on polyaspartate inhibitors of calcium and barium mineral scales. The optimum molecular weight for polyaspartate inhibitors of calcium carbonate, calcium sulfate and barium sulfate mineral scales was determined to be between 1,000 and 4,000 Mw (weight average molecular weight as calculated by Size Exclusion Chromatography). For inhibition of calcium carbonate and barium sulfate, polyaspartates in the range of 3,000-4,000 Mw were most effective. For calcium sulfate inhibition, the optimum molecular weight lies in the 1,000 to 2,000 Mw range. Biodegradability data (OECD 301B Ready Biodegradability) on polyaspartates of a variety of molecular weights is also presented which demonstrates the high biodegradability of this class of mineral scale inhibitors.

  14. Polyaspartate scale inhibitors -- Biodegradable alternatives to polyacrylates

    SciTech Connect

    Ross, R.J.; Low, K.C.; Shannon, J.E.

    1997-04-01

    Polyaspartates are highly biodegradable alternatives to polyacrylate-based scale inhibitors. This article presents laboratory testing data on polyaspartate inhibitors of calcium and barium mineral scales. The optimum molecular weight (Mw) for polyaspartate inhibitors of calcium carbonate, calcium sulfate, and barium sulfate mineral scales was determined to be between 1,000 Mw and 4,000 Mw. For inhibition of calcium carbonate and barium sulfate, polyaspartates in the range of 3,000 Mw to 4,000 Mw were most effective. For calcium sulfate inhibition, the optimum Mw lies in the 1,000 Mw to 2,000 Mw range. Biodegradability data (OECD 301B Ready Biodegradability) on polyaspartates of a variety of Mw is also presented, which demonstrates the high biodegradability of this class of mineral scale inhibitors.

  15. Toxicity of peracetic acid (PAA) to tomonts of Ichthyophthirius multifiliis

    USDA-ARS?s Scientific Manuscript database

    The free-living infective theront of Ichthyophthirius multifiliis historically has been thought to be the only stage susceptible to treatment. A technique is introduced to determine the toxicity of compounds to the detached trophont, the settled tomont and the developing tomites within the tomont t...

  16. Collapse of sodium polyacrylate chains in calcium salt solutions

    NASA Astrophysics Data System (ADS)

    Schweins, R.; Huber, K.

    The sodium salt of polyacrylic acid (NaPA) precipitates in the presence of Ca^{2+}-ions. This phase behaviour can be represented by a phase diagram where the critical NaPA concentration is plotted versus the critical Ca^{2+} concentration resulting in a straight line as a phase boundary. The location of this phase boundary is influenced by the presence of an inert monovalent salt like NaCl. The present contribution focuses on the coil dimensions of NaPA chains in dilute aqueous solution corresponding to the one phase region of such a phase diagram. A variety of parameters with which the size and shape of the polyelectrolyte chains can be modulated are revealed. Approaching the phase boundary by decreasing the NaPA concentration at a constant Ca^{2+} content leads to a collapse of the NaPA chains. Combined static and dynamic light scattering suggests a compact spherical shape as the final state of this transition, both in 0.1 M NaCl and in 0.01 M NaCl. In the lower NaCl concentration, indication is presented for the existence of a cigar or pearl necklace like intermediate. Most strikingly, the collapsed chains can be reexpanded by increasing the concentration of inert NaCl at constant content of NaPA and Ca^{2+}. Clearly, excessive Na+-ions displace the Ca^{2+}-ions from the NaPA chains.

  17. [Action mechanism of sodium polyacrylates against stomach ulcer].

    PubMed

    Kokue, E; Hayama, T

    1975-05-01

    Three sodium polyacrylates (PAS) with different viscosities were examined for antiulcerogenic properties. Rats were fed with sugar containing a PAS for 4 hr and subjected to 12 hr reserpinization or stress by water immersion. Lower incidence of ulceration and larger amount of stomach content after the experiment were found in the PAS administered groups. The higher viscous PAS was more effective in prevention of ulceration and in prolongation of gastric emptying. Intragastric administration of the drugs to pylorus ligated rats reduced forestomach ulceration. However, differences in the antiulcerogenic activity of three drugs were not observed. The effects on the gastric secretion of three PAS (50 mg) were also examined, using pylorus ligated (6 hr) rats. In PAS groups, the free acid in the gastric juice was reduced to some extent. There was, however, no relation between the antiacid effect and viscosity. The drugs inhibited the peptic digestion in vitro, but the difference of viscosity was not related to the antipeptic effect. It is concluded that prolongation of gastric emptying may be a major factor in the antiulcerogenic activity of PAS.

  18. In vitro release of clomipramine HCl and buprenorphine HCl from poly adipic anhydride (PAA) and poly trimethylene carbonate (PTMC) blends.

    PubMed

    Dinarvand, Rassoul; Alimorad, Mohammed Massoud; Amanlou, Massoud; Akbari, Hamid

    2005-10-01

    Controlled drug-delivery technology is concerned with the systematic release of a pharmaceutical agent to maintain a therapeutic level of the drug in the body for modulated and/or prolonged periods of time. This may be achieved by incorporating the therapeutic agent into a degradable polymer vehicle, which releases the agent continuously as the matrix erodes. In this study, poly trimethylene carbonate (PTMC), an aliphatic polycarbonate, and poly adipic anhydride (PAA), an aliphatic polyanhydride, were synthesized via melt condensation and ring-opening polymerization of trimethylene carbonate and adipic acid, respectively. The release of clomipramine HCl and buprenorphine HCl from discs prepared with the use of PTMC-PAA blends in phosphate buffer (pH 7.4) are also described. Clomipramine HCl and buprenorphine HCl were both used as hydrophilic drug models. Theoretical treatment of the data with the Peppas model revealed that release of clomipramine HCl (5%) in devices containing 70% PTMC or more followed a Fickian diffusion model. However, the releases of buprenorphine HCl (5%) in the same devices were anomalous. For devices containing 50% and more PAA, surface erosion may play a significant role in the release of both molecules.

  19. Micelle-assisted signaling of peracetic acid by the oxidation of pyreneboronic acid via monomer-excimer switching.

    PubMed

    Choi, Jiyoung; Lee, Hyo Jin; Cho, Min Jeoung; Chang, Suk-Kyu

    2015-08-15

    A simple fluorescent probe for the industrial oxidant peracetic acid (PAA) was investigated. PAA-assisted oxidative conversion of pyrene-1-boronic acid into 1-hydroxypyrene was used as the signaling tool. Pyreneboronic acid was found to display selective signaling behavior, being more responsive to PAA than to other commonly used practical oxidants such as H2O2 and HOCl. The changes in pyrene monomer fluorescence to excimer were used in the quantitative analysis of PAA. When using the surfactant hexadecyltrimethylammonium bromide as a micellar additive, the signaling of PAA was markedly enhanced. Selective fluorescence signaling of PAA by pyrene-1-boronic acid with a detection limit of 1.5×10(-6)M in aqueous environment was successfully achieved.

  20. The influence of colloidal parameters on the specific power absorption of PAA-coated magnetite nanoparticles

    PubMed Central

    2011-01-01

    The suitability of magnetic nanoparticles (MNPs) to act as heat nano-sources by application of an alternating magnetic field has recently been studied due to their promising applications in biomedicine. The understanding of the magnetic relaxation mechanism in biocompatible nanoparticle systems is crucial in order to optimize the magnetic properties and maximize the specific absorption rate (SAR). With this aim, the SAR of magnetic dispersions containing superparamagnetic magnetite nanoparticles bio-coated with polyacrylic acid of an average particle size of ≈10 nm has been evaluated separately by changing colloidal parameters such as the MNP concentration and the viscosity of the solvent. A remarkable decrease of the SAR values with increasing particle concentration and solvent viscosity was found. These behaviours have been discussed on the basis of the magnetic relaxation mechanisms involved. PACS: 80; 87; 87.85jf PMID:21711915

  1. Taxis of Pseudomonas putida F1 toward Phenylacetic Acid Is Mediated by the Energy Taxis Receptor Aer2

    PubMed Central

    Luu, Rita A.; Schneider, Benjamin J.; Ho, Christie C.; Nesteryuk, Vasyl; Ngwesse, Stacy E.; Liu, Xianxian; Parales, Juanito V.; Ditty, Jayna L.

    2013-01-01

    The phenylacetic acid (PAA) degradation pathway is a widely distributed funneling pathway for the catabolism of aromatic compounds, including the environmental pollutants styrene and ethylbenzene. However, bacterial chemotaxis to PAA has not been studied. The chemotactic strain Pseudomonas putida F1 has the ability to utilize PAA as a sole carbon and energy source. We identified a putative PAA degradation gene cluster (paa) in P. putida F1 and demonstrated that PAA serves as a chemoattractant. The chemotactic response was induced during growth with PAA and was dependent on PAA metabolism. A functional cheA gene was required for the response, indicating that PAA is sensed through the conserved chemotaxis signal transduction system. A P. putida F1 mutant lacking the energy taxis receptor Aer2 was deficient in PAA taxis, indicating that Aer2 is responsible for mediating the response to PAA. The requirement for metabolism and the role of Aer2 in the response indicate that P. putida F1 uses energy taxis to detect PAA. We also revealed that PAA is an attractant for Escherichia coli; however, a mutant lacking a functional Aer energy receptor had a wild-type response to PAA in swim plate assays, suggesting that PAA is detected through a different mechanism in E. coli. The role of Aer2 as an energy taxis receptor provides the potential to sense a broad range of aromatic growth substrates as chemoattractants. Since chemotaxis has been shown to enhance the biodegradation of toxic pollutants, the ability to sense PAA gradients may have implications for the bioremediation of aromatic hydrocarbons that are degraded via the PAA pathway. PMID:23377939

  2. Taxis of Pseudomonas putida F1 toward phenylacetic acid is mediated by the energy taxis receptor Aer2.

    PubMed

    Luu, Rita A; Schneider, Benjamin J; Ho, Christie C; Nesteryuk, Vasyl; Ngwesse, Stacy E; Liu, Xianxian; Parales, Juanito V; Ditty, Jayna L; Parales, Rebecca E

    2013-04-01

    The phenylacetic acid (PAA) degradation pathway is a widely distributed funneling pathway for the catabolism of aromatic compounds, including the environmental pollutants styrene and ethylbenzene. However, bacterial chemotaxis to PAA has not been studied. The chemotactic strain Pseudomonas putida F1 has the ability to utilize PAA as a sole carbon and energy source. We identified a putative PAA degradation gene cluster (paa) in P. putida F1 and demonstrated that PAA serves as a chemoattractant. The chemotactic response was induced during growth with PAA and was dependent on PAA metabolism. A functional cheA gene was required for the response, indicating that PAA is sensed through the conserved chemotaxis signal transduction system. A P. putida F1 mutant lacking the energy taxis receptor Aer2 was deficient in PAA taxis, indicating that Aer2 is responsible for mediating the response to PAA. The requirement for metabolism and the role of Aer2 in the response indicate that P. putida F1 uses energy taxis to detect PAA. We also revealed that PAA is an attractant for Escherichia coli; however, a mutant lacking a functional Aer energy receptor had a wild-type response to PAA in swim plate assays, suggesting that PAA is detected through a different mechanism in E. coli. The role of Aer2 as an energy taxis receptor provides the potential to sense a broad range of aromatic growth substrates as chemoattractants. Since chemotaxis has been shown to enhance the biodegradation of toxic pollutants, the ability to sense PAA gradients may have implications for the bioremediation of aromatic hydrocarbons that are degraded via the PAA pathway.

  3. Stability effect of cholesterol-poly(acrylic acid) in a stimuli-responsive polymer-liposome complex obtained from soybean lecithin for controlled drug delivery.

    PubMed

    Simões, M G; Alves, P; Carvalheiro, Manuela; Simões, P N

    2017-04-01

    The development of polymer-liposome complexes (PLCs), in particular for biomedical applications, has grown significantly in the last decades. The importance of these studies comes from the emerging need in finding intelligent controlled release systems, more predictable, effective and selective, for applications in several areas, such as treatment and/or diagnosis of cancer, neurological, dermatological, ophthalmic and orthopedic diseases, gene therapy, cosmetic treatments, and food engineering. This work reports the development and characterization of a pH sensitive system for controlled release based on PLCs. The selected hydrophilic polymer was poly(acrylic acid) (PAA) synthesized by atom transfer radical polymerization (ATRP) with a cholesterol (CHO) end-group to improve the anchoring of the polymer into the lipid bilayer. The polymer was incorporated into liposomes formulated from soybean lecithin and stearylamine, with different stearylamine/phospholipid and polymer/phospholipid ratios (5, 10 and 20%). The developed PLCs were characterized in terms of particle size, polydispersity, zeta potential, release profiles, and encapsulation efficiency. Cell viability studies were performed to assess the cytotoxic potential of PLCs. The results showed that the liposomal formulation with 5% of stearylamine and 10% of polymer positively contribute to the stabilization of the complexes. Afterwards, the carboxylic acid groups of the polymer present at the surface of the liposomes were crosslinked and the same parameters analyzed. The crosslinked complexes showed to be more stable at physiologic conditions. In addition, the release profiles at different pHs (2-12) revealed that the obtained complexes released all their content at acidic conditions. In summary, the main accomplishments of this work are: (i) innovative synthesis of cholesterol-poly(acrylic acid) (CHO-PAA) by ATRP; (ii) stabilization of the liposomal formulation by incorporation of stearylamine and CHO-PAA

  4. Distinct Characteristics of Indole-3-Acetic Acid and Phenylacetic Acid, Two Common Auxins in Plants

    PubMed Central

    Sugawara, Satoko; Mashiguchi, Kiyoshi; Tanaka, Keita; Hishiyama, Shojiro; Sakai, Tatsuya; Hanada, Kousuke; Kinoshita-Tsujimura, Kaori; Yu, Hong; Dai, Xinhua; Takebayashi, Yumiko; Takeda-Kamiya, Noriko; Kakimoto, Tatsuo; Kawaide, Hiroshi; Natsume, Masahiro; Estelle, Mark; Zhao, Yunde; Hayashi, Ken-ichiro; Kamiya, Yuji; Kasahara, Hiroyuki

    2015-01-01

    The phytohormone auxin plays a central role in many aspects of plant growth and development. IAA is the most studied natural auxin that possesses the property of polar transport in plants. Phenylacetic acid (PAA) has also been recognized as a natural auxin for >40 years, but its role in plant growth and development remains unclear. In this study, we show that IAA and PAA have overlapping regulatory roles but distinct transport characteristics as auxins in plants. PAA is widely distributed in vascular and non-vascular plants. Although the biological activities of PAA are lower than those of IAA, the endogenous levels of PAA are much higher than those of IAA in various plant tissues in Arabidopsis. PAA and IAA can regulate the same set of auxin-responsive genes through the TIR1/AFB pathway in Arabidopsis. IAA actively forms concentration gradients in maize coleoptiles in response to gravitropic stimulation, whereas PAA does not, indicating that PAA is not actively transported in a polar manner. The induction of the YUCCA (YUC) genes increases PAA metabolite levels in Arabidopsis, indicating that YUC flavin-containing monooxygenases may play a role in PAA biosynthesis. Our results provide new insights into the regulation of plant growth and development by different types of auxins. PMID:26076971

  5. Glycosylated polyacrylate nanoparticles by emulsion polymerization

    PubMed Central

    Abeylath, Sampath C.; Turos, Edward

    2007-01-01

    A selection of glycosylated polyacrylate nanoparticles has been prepared by radical-initiated emulsion polymerization in aqueous media. Using ethyl acrylate as a co-monomer, carbohydrate acrylates were incorporated into the poly(ethyl acrylate) framework to give stable emulsions of glyconanoparticles with an average particle size of around 40 nm. Using this technique a variety of glyconanoparticles were prepared from 3-O-acryloyl-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose, 1-O-acryloyl-2,3:5,6-di-O-isopropylidene-α-D-mannofuranose, 6-O-acryloyl-1,2:3,4-di-O-isopropylidene-α-D-galactopyranose, 2-N-acryloyl-1,3,4,6-tetra-O-acetyl-β-D-glucosamine, 5-O-acryloyl-2,3-isopropylidene-1-methoxy-β-D-ribofuranose and 4-N-acetyl-5’-O-acryloyl-2’,3’-O-isopropylidene cytidine. Scanning electron microscopy, dynamic light scattering and proton NMR analysis of the emulsions indicated essentially 100% incorporation of the carbohydrate acrylate monomer into the polymer with the exception of O-benzyl- and O-benzoyl-protected carbohydrate acrylates, which gave incomplete incorporation. Formation of larger glyconanoparticles of ~80nm with (unprotected) 3-O-acryloyl-D-glucose and 5-O-acryloyl-1-methoxy-β-D-ribofuranose revealed the influence of free hydroxyl groups in the monomer on the particle size during polymerization, a feature which is also apparently dependent on the amount of carbohydrate in the matrix. This methodology allows for a new, simple route to the synthesis of polymeric glyconanoparticles with potential applications in targeted drug delivery and materials development. PMID:18677404

  6. Functionalized graphene and graphene oxide solution via polyacrylate coating

    NASA Astrophysics Data System (ADS)

    Saha, Arindam; Basiruddin, Sk; Ray, S. C.; Roy, S. S.; Jana, Nikhil R.

    2010-12-01

    Water soluble graphene with various chemical- and biofunctionalities is essential for their different applications. However, exfoliated graphenes are insoluble in water and water soluble graphene oxide precipitate if they are chemically reduced to graphene. We have developed a polyacrylate coating method for graphene oxide and then chemically reduced it into graphene. We found that polyacrylate coating can improve the colloidal stability of both graphene and graphene oxide. The coated graphene has been characterized using XPS, FTIR, XRD and micro-Raman spectroscopy. The primary amine present on the coating backbone has been used to derive glucose functionalized water soluble graphene. Various other functional graphenes can be anticipated from the polyacrylate coated graphene.Water soluble graphene with various chemical- and biofunctionalities is essential for their different applications. However, exfoliated graphenes are insoluble in water and water soluble graphene oxide precipitate if they are chemically reduced to graphene. We have developed a polyacrylate coating method for graphene oxide and then chemically reduced it into graphene. We found that polyacrylate coating can improve the colloidal stability of both graphene and graphene oxide. The coated graphene has been characterized using XPS, FTIR, XRD and micro-Raman spectroscopy. The primary amine present on the coating backbone has been used to derive glucose functionalized water soluble graphene. Various other functional graphenes can be anticipated from the polyacrylate coated graphene. Electronic supplementary information (ESI) available: Details of XPS, XRD, AFM and FTIR of polymer coated GO and G and results of fluorescence quenching experiments. See DOI: 10.1039/c0nr00376j

  7. Degradation of Sodium-Polyacrylate in Dilute Aqueous Solution, II

    NASA Astrophysics Data System (ADS)

    Saita, Takao; Matumura, On

    1983-08-01

    It has been found that Na-PAA molecules in dilute aqueous solution are degraded by shearing stress, oxidation and photolysis during usual viscosity measurements with a capillary viscometer. The results of previous viscosity measurements, mainly about the mechanochemical degradation in air and in air-free conditions, showed that the degradation rate increases with increasing shear stress, and with decreasing polymer concentration. In this work, the effects of the molecular weight and temperature on the degradation rate are measured using a capillary viscometer in air, and the photodegradation of Na-PAA and PAA in aqueous solution irradiated with UV light are studied by viscosity measurements in air, and by UV absorption and ESR methods. The results show that the degradation of molecules is enhanced by an increase in the molecular weight and strongly accelerated by a rise in temperature and by UV irradiation, and is accompanied by free-radical chain reactions.

  8. Acid-catalytic decomposition of peracetic acid in the liquid phase

    SciTech Connect

    Kharchuk, V.G.; Kolenko, I.P.; Petrov, L.A.

    1985-12-01

    This paper elucidates the kinetic relationships of peracetic acid (PAA) decomposition in the presence of mineral acids and their heterogeneous analogs, polystyrene-di-vinylbenzene cation-exchangers, differing in physicochemical and morphological parameters. It is shown that the thermal decomposition of PAA in acetic acid is an acid-catalyzed reaction. The controlling step of the reaction is protonation of the substrate with formation of an active intermediate form. Sulfonated cation-exchangers are twice as effective as sulfuric acid in this process. Polystyrene-divinylbenzene sulfonated cation-exchangers can be used with success as acid catalysts in oxidation processes involving PAA, because of their high effectiveness, stability, and availability.

  9. Analyzing freely dissolved concentrations of cationic surfactant utilizing ion-exchange capability of polyacrylate coated solid-phase microextraction fibers.

    PubMed

    Chen, Yi; Droge, Steven T J; Hermens, Joop L M

    2012-08-24

    A 7-μm polyacrylate (PA) coated fiber was successfully employed to determine freely dissolved concentrations of cationic surfactants by solid-phase microextraction (SPME) and utilizing the capability of the PA-coating to sorb organic cations via ion-exchange at carboxylic groups. Measured fiber-water partitioning coefficients (K(fw)) were constant below a fiber loading of 2mmol per liter polyacrylate, allowing for simple and accurate analysis in a concentration range that is relevant from a risk assessment point of view. Ion-exchange was confirmed to be the main sorption mechanism because of a decreasing K(fw) with either higher CaCl(2) concentrations or lower pH, and maximum fiber uptake at the polyacrylate cation-exchange capacity (CEC, at 30mmol/L PA). Fiber-water sorption isotherms were established in various aqueous media in toxicological relevant concentrations. The developed SPME method has a high potential for application in ecotoxicological studies, as demonstrated in sorption studies with humic acid in different electrolyte solutions at aqueous concentrations down to the sub nM range. Cationic surfactant sorption affinities for humic acid also depend on medium composition but are orders of magnitude higher than to the PA fiber on a sorbent weight basis. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Probing structure-antifouling activity relationships of polyacrylamides and polyacrylates.

    PubMed

    Zhao, Chao; Zhao, Jun; Li, Xiaosi; Wu, Jiang; Chen, Shenfu; Chen, Qiang; Wang, Qiuming; Gong, Xiong; Li, Lingyan; Zheng, Jie

    2013-07-01

    We have synthesized two different polyacrylamide polymers with amide groups (polySBAA and polyHEAA) and two corresponding polyacrylate polymers without amide groups (polySBMA and polyHEA), with particular attention to the evaluation of the effect of amide group on the hydration and antifouling ability of these systems using both computational and experimental approaches. The influence of polymer architectures of brushes, hydrogels, and nanogels, prepared by different polymerization methods, on antifouling performance is also studied. SPR and ELISA data reveal that all polymers exhibit excellent antifouling ability to repel proteins from undiluted human blood serum/plasma, and such antifouling ability can be further enhanced by presenting amide groups in polySBAA and polyHEAA as compared to polySBMA and polyHEA. The antifouling performance is positively correlated with the hydration properties. Simulations confirm that four polymers indeed have different hydration characteristics, while all presenting a strong hydration overall. Integration of amide group with pendant hydroxyl or sulfobetaine group in polymer backbones is found to increase their surface hydration of polymer chains and thus to improve their antifouling ability. Importantly, we present a proof-of-concept experiment to synthesize polySBAA nanogels, which show a switchable property between antifouling and pH-responsive functions driven by acid-base conditions, while still maintaining high stability in undiluted fetal bovine serum and minimal toxicity to cultured cells. This work provides important structural insights into how very subtle structural changes in polymers can yield great improvement in biological activity, specifically the inclusion of amide group in polymer backbone/sidechain enables to obtain antifouling materials with better performance for biomedical applications.

  11. Improved Cycling Performance of a Si Nanoparticle Anode Utilizing Citric Acid as a Surface-Modifying Agent.

    PubMed

    Nguyen, Cao Cuong; Seo, Daniel M; Chandrasiri, K W D K; Lucht, Brett L

    2017-09-19

    Citric acid and its analogues have been investigated as surface-modifying agents for Si nanoparticle anodes using electrochemical cycling, attenuated total reflectance infrared (ATR IR), and X-ray photoelectron spectroscopy (XPS). A Si nanoparticle anode prepared with citric acid (CA) has better capacity retention than one containing 1,2,3,4-butanetetracarboxylic acid (BA), but both electrodes outperform Si-PVDF. The Si-CA anode has an initial specific capacity of 3530 mA h/g and a first cycle efficiency of 82%. Surprisingly, the Si-CA electrode maintains a high specific capacity of ∼2200 mA h/g after 250 cycles, corresponding to 64% capacity retention, which is similar to the Si prepared with long-chain poly(acrylic acid) (PAA). On the contrary, the silicon electrode prepared with PVDF has a fast capacity fade and retains only 980 mA h/g after 50 cycles. The IR and XPS data show that the Si-CA electrode has an SEI composed primarily of lithium citrate during the first 50 cycles, resulting from the electrochemical reduction of citric acid. Only low concentrations of electrolyte reduction products are observed. The lithium citrate layer derived from CA stabilizes the silicon surface and suppresses electrolyte reduction, which likely contributes to the enhanced cycling performance of the Si nanoparticle anode.

  12. UV-induced graft polymerization of acrylic acid in the sub-micronchannels of oxidized PET track-etched membrane

    NASA Astrophysics Data System (ADS)

    Korolkov, Ilya V.; Mashentseva, Anastassiya A.; Güven, Olgun; Taltenov, Abzal A.

    2015-12-01

    In this article, we report on functionalization of track-etched membrane based on poly(ethylene terephthalate) (PET TeMs) oxidized by advanced oxidation systems and by grafting of acrylic acid using photochemical initiation technique for the purpose of increasing functionality thus expanding its practical application. Among advanced oxidation processes (H2O2/UV) system had been chosen to introduce maximum concentration of carboxylic acid groups. Benzophenone (BP) photo-initiator was first immobilized on the surfaces of cylindrical pores which were later filled with aq. acrylic acid solution. UV-irradiation from both sides of PET TeMs has led to the formation of grafted poly(acrylic acid) (PAA) chains inside the membrane sub-micronchannels. Effect of oxygen-rich surface of PET TeMs on BP adsorption and subsequent process of photo-induced graft polymerization of acrylic acid (AA) were studied by ESR. The surface of oxidized and AA grafted PET TeMs was characterized by UV-vis, ATR-FTIR, XPS spectroscopies and by SEM.

  13. Peracetic acid oxidation of saline waters in the absence and presence of H ₂O ₂: secondary oxidant and disinfection byproduct formation.

    PubMed

    Shah, Amisha D; Liu, Zheng-Qian; Salhi, Elisabeth; Höfer, Thomas; von Gunten, Urs

    2015-02-03

    Peracetic acid (PAA) is a disinfectant considered for use in ballast water treatment, but its chemical behavior in such systems (i.e., saline waters) is largely unknown. In this study, the reactivity of PAA with halide ions (chloride and bromide) to form secondary oxidants (HOCl, HOBr) was investigated. For the PAA-chloride and PAA-bromide reactions, second-order rate constants of (1.47 ± 0.58) × 10(-5) and 0.24 ± 0.02 M(-1) s(-1) were determined for the formation of HOCl or HOBr, respectively. Hydrogen peroxide (H2O2), which is always present in PAA solutions, reduced HOCl or HOBr to chloride or bromide, respectively. As a consequence, in PAA-treated solutions with [H2O2] > [PAA], the HOBr (HOCl) steady-state concentrations were low with a limited formation of brominated (chlorinated) disinfection byproducts (DBPs). HOI (formed from the PAA-iodide reaction) affected this process because it can react with H2O2 back to iodide. H2O2 is thus consumed in a catalytic cycle and leads to less efficient HOBr scavenging at even low iodide concentrations (<1 μM). In PAA-treated solutions with [H2O2] < [PAA] and high bromide levels, mostly brominated DBPs are formed. In synthetic water, bromate was formed from the oxidation of bromide. In natural brackish waters, bromoform (CHBr3), bromoacetic acid (MBAA), dibromoacetic acid (DBAA), and tribromoacetic acid (TBAA) formed at up to 260, 106, 230, and 89 μg/L, respectively for doses of 2 mM (ca. 150 mg/L) PAA and [H2O2] < [PAA]. The same brackish waters, treated with PAA with [H2O2] ≫ [PAA], similar to conditions found in commercial PAA solutions, resulted in no trihalomethanes and only low haloacetic acid concentrations.

  14. Elucidating the role of the phenylacetic acid metabolic complex in the pathogenic activity of Rhizoctonia solani anastomosis group 3.

    PubMed

    Bartz, Faith E; Glassbrook, Norman J; Danehower, David A; Cubeta, Marc A

    2012-01-01

    The soil fungus Rhizoctonia solani produces phytotoxic phenylacetic acid (PAA) and hydroxy (OH-) and methoxy (MeO-) derivatives of PAA. However, limited information is available on the specific role that these compounds play in the development of Rhizoctonia disease symptoms and concentration(s) required to induce a host response. Reports that PAA inhibits the growth of R. solani conflict with the established ability of the fungus to produce and metabolize PAA. Experiments were conducted to clarify the role of the PAA metabolic complex in Rhizoctonia disease. In this study the concentration of PAA and derivatives required to induce tomato root necrosis and stem canker, in the absence of the fungus, and the concentration that inhibits mycelial growth of R. solani were determined. The effect of exogenous PAA and derivatives of PAA on tomato seedling growth also was investigated. Growth of tomato seedlings in medium containing 0.1-7.5 mM PAA and derivatives induced necrosis of up to 85% of root system. Canker development resulted from injection of tomato seedling stems with 7.5 mM PAA, 3-OH-PAA, or 3-MeO-PAA. PAA in the growth medium reduced R. solani biomass, with 50% reduction observed at 7.5 mM. PAA, and derivatives were quantified from the culture medium of 14 isolates of R. solani belonging to three distinct anastomosis groups by GC-MS. The quantities ranged from below the limit of detection to 678 nM, below the concentrations experimentally determined to be phytotoxic. Correlation analyses revealed that isolates of R. solani that produced high PAA and derivatives in vitro also caused high mortality on tomato seedlings. The results of this investigation add to the body of evidence that the PAA metabolic complex is involved in Rhizoctonia disease development but do not indicate that production of these compounds is the primary or the only determinant of pathogenicity.

  15. Use of peracetic acid to disinfect water: toxicity to fish

    USDA-ARS?s Scientific Manuscript database

    There has been strong interest in aquaculture for the use of peracetic acid (PAA) as a disinfectant to prevent freshwater fish pathogens. PAA is a stabilized mixture of acetic acid, hydrogen peroxide and water that does not leave dangerous residues in the environment when it breaks down as most com...

  16. Preparation and icephobic properties of polymethyltrifluoropropylsiloxane-polyacrylate block copolymers

    NASA Astrophysics Data System (ADS)

    Li, Xiaohui; Zhao, Yunhui; Li, Hui; Yuan, Xiaoyan

    2014-10-01

    Five polymethyltrifluoropropylsiloxane (PMTFPS)-polyacrylate block copolymers (PMTFPS-b-polyacrylate) were synthesized by free radical polymerization of methyl methacrylate, n-butyl acrylate and hydroxyethyl methacrylate using PMTFPS macroazoinitiator (PMTFPS-MAI) in range of 10-50 mass percentages. The morphology, surface chemical composition and wettability of the prepared copolymer films were investigated by transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and water contact angle measurement. Delayed icing time and ice shear strength of the films were also detected for the icephobic purpose. The surface morphologies of the copolymers were different from those of the bulk because of the migration of the PMTFPS segments to the air interface during the film formation. Maximal delayed icing time (186 s at -15 °C) and reduction of the ice shear strength (301 ± 10 kPa) which was significantly lower than that of polyacrylates (804 ± 37 kPa) were achieved when the content of PMTFPS-MAI was 20 wt%. The icephobicity of the copolymers was attributed primarily to the enrichment of PMTFPS on the film surface and synergistic effect of both silicone and fluorine. Thus, the results show that the PMTFPS-b-polyacrylate copolymer can be used as icephobic coating materials potentially.

  17. Peracetic acid-ionic liquid pretreatment to enhance enzymatic saccharification of lignocellulosic biomass.

    PubMed

    Uju; Abe, Kojiro; Uemura, Nobuyuki; Oshima, Toyoji; Goto, Masahiro; Kamiya, Noriho

    2013-06-01

    To enhance enzymatic saccharification of pine biomass, the pretreatment reagents peracetic acid (PAA) and ionic liquid (IL) were validated in single reagent pretreatments or combination pretreatments with different sequences. In a 1h saccharification, 5-25% cellulose conversion was obtained from the single pretreatment of PAA or IL. In contrast, a marked enhancement in conversion rates was achieved by PAA-IL combination pretreatments (45-70%). The PAA followed by IL (PAA+IL) pretreatment sequence was the most effective for preparing an enzymatic digestible regenerated biomass with 250-fold higher glucose formation rates than untreated biomass and 2- to 12-fold higher than single pretreatments with PAA or IL alone. Structural analysis confirmed that this pretreatment resulted in biomass with highly porous structural fibers associated with the reduction of lignin content and acetyl groups. Using the PAA+IL sequence, biomass loading in the pretreatment step can be increased from 5% to 15% without significant decrease in cellulose conversion.

  18. External polyacrylate-coating as alternative material for preparation of photopolymerized sol-gel monolithic column.

    PubMed

    Vaz, Fernando Antonio Simas; de Castro, Patrícia Mendonça; Molina, Celso; Ribeiro, Sidney José Lima; Polachini, Ferminio César; Messaddeq, Younes; Nunes, Adriana Palombo; de Oliveira, Marcone Augusto Leal

    2008-06-30

    Photopolymerized sol-gel monolithic columns for use in capillary electrochromatography were prepared in 125 microm i.d. polyacrylate-coated fused-silica capillaries. The polyacrylate-coating, unlike the polyimide one, is transparent to the radiation used (approximately 370 nm), and thus, no coating removal is necessary. This is a very important particularity since intrinsic capillary column characteristics, such as flexibility and mechanical resistance, are unchanged. A mixture containing metacryloxypropyltrimethoxysilane (MPTMS) as the polymeric precursor, hydrochloric acid as the catalyst, toluene as the porogen and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819) as the photoinitiator was irradiated at 370 nm for 20 min inside the capillaries to prepare the columns through sol-gel approach. The versatility and viability of the use of polyacrilate as a new capillary external coating were shown through preparation of two columns under different conditions, which were tested in electrochromatography for separation of standard mixture containing thiourea (marker compound), propylbenzene, phenanthrene and pyrene.

  19. Improvement in soil and sorghum health following the application of polyacrylate polymers to a Cd-contaminated soil.

    PubMed

    Guiwei, Q; de Varennes, A; Martins, L L; Mourato, M P; Cardoso, A I; Mota, A M; Pinto, A P; Gonçalves, M L

    2010-01-15

    Contamination of soils with cadmium (Cd) is a serious global issue due to its high mobility and toxicity. We investigated the application of insoluble polyacrylate polymers to improve soil and plant health. Sorghum was grown in a Cd-contaminated sandy soil. Polyacrylate polymers at 0.2% (w/w) were added to half of the soil. Control soil without plants was also included in the experiment. Growth of sorghum was stimulated in the polymer-amended soil. The concentration of Cd in the shoots, and the activities of catalase and ascorbate peroxidase decreased in plants from polymer-amended soil compared with unamended control. The amount of CaCl(2)-extractable Cd in the polymer-amended soil was 55% of that in the unamended soil. The Cd extracted in sorghum shoots was 0.19 mg per plant grown on soil without polymer and 0.41 mg per plant grown on polymer-amended soil. The total amount of Cd removed from each pot corresponded to 1.5 and more than 6% of soil CaCl(2)-extractable Cd in unamended and polymer-amended soil, respectively. The activities of soil acid phosphatase, beta-glucosidase, urease, protease and cellulase were greatest in polymer-amended soil with sorghum. In conclusion, the application of polyacrylate polymers to reduce the bioavailable Cd pool seems a promising method to enhance productivity and health of plants grown on Cd-contaminated soils.

  20. Comparing peracetic acid and hypochlorite for disinfection of combined sewer overflows: Effects of suspended-solids and pH.

    PubMed

    McFadden, M; Loconsole, J; Schockling, A J; Nerenberg, R; Pavissich, J P

    2017-12-01

    Peracetic acid (PAA) is an alternative disinfectant that may be effective for combined sewer overflow (CSO) disinfection, but little is known about the effect of particle size on PAA disinfection efficiency. In this work, PAA and hypochlorite were compared as disinfectants, with a focus on the effect of wastewater particles. Inactivation experiments were conducted on suspended cultures of Escherichia coli and wastewater suspended solids. Tested size fractions included particle diameters <10μm, <100μm, and raw wastewater. Chlorine disinfection efficiency decreased with increasing solids size. However, solids size had little effect on PAA disinfection. The PAA disinfection efficiency decreased at pH values above 7.5. Live/dead staining revealed that PAA disinfection leaves most cells in a viable but non-culturable condition. Fourier transform infrared spectroscopy (FTIR) analyses suggests that PAA and hypochlorite may inactivate E. coli bacteria by similar mechanisms. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Auxin Biosynthesis: Are the Indole-3-Acetic Acid and Phenylacetic Acid Biosynthesis Pathways Mirror Images?1[OPEN

    PubMed Central

    Nichols, David S.; Smith, Jason; Chourey, Prem S.; McAdam, Erin L.; Quittenden, Laura

    2016-01-01

    The biosynthesis of the main auxin in plants (indole-3-acetic acid [IAA]) has been elucidated recently and is thought to involve the sequential conversion of Trp to indole-3-pyruvic acid to IAA. However, the pathway leading to a less well studied auxin, phenylacetic acid (PAA), remains unclear. Here, we present evidence from metabolism experiments that PAA is synthesized from the amino acid Phe, via phenylpyruvate. In pea (Pisum sativum), the reverse reaction, phenylpyruvate to Phe, is also demonstrated. However, despite similarities between the pathways leading to IAA and PAA, evidence from mutants in pea and maize (Zea mays) indicate that IAA biosynthetic enzymes are not the main enzymes for PAA biosynthesis. Instead, we identified a putative aromatic aminotransferase (PsArAT) from pea that may function in the PAA synthesis pathway. PMID:27208245

  2. Resistance to and killing by the sporicidal microbicide peracetic acid.

    PubMed

    Leggett, Mark J; Schwarz, J Spencer; Burke, Peter A; Mcdonnell, Gerald; Denyer, Stephen P; Maillard, Jean-Yves

    2015-03-01

    To elucidate the mechanisms of spore resistance to and killing by the oxidizing microbicide peracetic acid (PAA). Mutants of Bacillus subtilis lacking specific spore structures were used to identify resistance properties in spores and to understand the mechanism of action of PAA. We also assessed the effect of PAA treatment on a number of spore properties including heat tolerance, membrane integrity and germination. The spore coat is essential for spore PAA resistance as spores with defective coats were greatly sensitized to PAA treatment. Small acid-soluble spore proteins apparently provide no protection against PAA. Defects in spore germination, specifically in germination via the GerB and GerK but not the GerA germination receptors, as well as leakage of internal components suggest that PAA is active at the spore inner membrane. It is therefore likely that the inner membrane is the major site of PAA's sporicidal activity. PAA treatment targets the spore membrane, with some of its activity directed specifically against the GerB and GerK germination receptors. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  3. Shell and core cross-linked poly(L-lysine)/poly(acrylic acid) complex micelles.

    PubMed

    Hsieh, Yi-Hsuan; Hsiao, Yung-Tse; Jan, Jeng-Shiung

    2014-12-21

    We report the versatility of polyion complex (PIC) micelles for the preparation of shell and core cross-linked (SCL and CCL) micelles with their surface properties determined by the constituent polymer composition and cross-linking agent. The negatively and positively charged PIC micelles with their molecular structure and properties depending on the mixing weight percentage and polymer molecular weight were first prepared by mixing the negatively and positively charged polyions, poly(acrylic acid) (PAA) and poly(L-lysine) (PLL). The feasibility of preparing SCL micelles was demonstrated by cross-linking the shell of the negatively and positively charged micelles using cystamine and genipin, respectively. The core of the micelles can be cross-linked by silica deposition to stabilize the assemblies. The shell and/or core cross-linked micelles exhibited excellent colloid stability upon changing solution pH. The drug release from the drug-loaded SCL micelles revealed that the controllable permeability of the SCL micelles can be achieved by tuning the cross-linking degree and the SCL micelles exhibited noticeable pH-responsive behavior with accelerated release under acidic conditions. With the versatility of cross-linking strategies, it is possible to prepare a variety of SCL and CCL micelles from PIC micelles.

  4. 21 CFR 173.73 - Sodium polyacrylate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...: (a) The additive is produced by the polymerization of acrylic acid and subsequent hydrolysis of the... mineral scale during the evaporation of beet sugar juice or cane sugar juice in the production of sugar in...

  5. 21 CFR 173.73 - Sodium polyacrylate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... conditions: (a) The additive is produced by the polymerization of acrylic acid and subsequent hydrolysis of... mineral scale during the evaporation of beet sugar juice or cane sugar juice in the production of sugar in...

  6. Intrinsically stretchable transparent electrodes based on silver-nanowire-crosslinked-polyacrylate composites.

    PubMed

    Hu, Weili; Niu, Xiaofan; Li, Lu; Yun, Sungryul; Yu, Zhibin; Pei, Qibing

    2012-08-31

    Stretchable transparent composites have been synthesized consisting of a silver nanowire (AgNW) network embedded in the surface layer of a crosslinked poly(acrylate) matrix. The interpenetrating networks of AgNWs and the crosslinked polymer matrix lead to high surface conductivity, high transparency, and rubbery elasticity. The presence of carboxylic acid groups on the polymer chains enhances the bonding between AgNWs and the polymer matrix, and further increases the stretchability of the composites. The sheet resistance of the composite electrode increases by only 2.3 times at 50% strain. Repeated stretching to 50% strain and relaxation only causes a small increase of the sheet resistance after 600 cycles. The morphology of the composites during reversible stretching and relaxation has been investigated to expound the conductivity changes.

  7. Intrinsically stretchable transparent electrodes based on silver-nanowire-crosslinked-polyacrylate composites

    NASA Astrophysics Data System (ADS)

    Hu, Weili; Niu, Xiaofan; Li, Lu; Yun, Sungryul; Yu, Zhibin; Pei, Qibing

    2012-08-01

    Stretchable transparent composites have been synthesized consisting of a silver nanowire (AgNW) network embedded in the surface layer of a crosslinked poly(acrylate) matrix. The interpenetrating networks of AgNWs and the crosslinked polymer matrix lead to high surface conductivity, high transparency, and rubbery elasticity. The presence of carboxylic acid groups on the polymer chains enhances the bonding between AgNWs and the polymer matrix, and further increases the stretchability of the composites. The sheet resistance of the composite electrode increases by only 2.3 times at 50% strain. Repeated stretching to 50% strain and relaxation only causes a small increase of the sheet resistance after 600 cycles. The morphology of the composites during reversible stretching and relaxation has been investigated to expound the conductivity changes.

  8. PAA: an R/bioconductor package for biomarker discovery with protein microarrays

    PubMed Central

    Turewicz, Michael; Ahrens, Maike; May, Caroline; Marcus, Katrin; Eisenacher, Martin

    2016-01-01

    Summary: The R/Bioconductor package Protein Array Analyzer (PAA) facilitates a flexible analysis of protein microarrays for biomarker discovery (esp., ProtoArrays). It provides a complete data analysis workflow including preprocessing and quality control, uni- and multivariate feature selection as well as several different plots and results tables to outline and evaluate the analysis results. As a main feature, PAA’s multivariate feature selection methods are based on recursive feature elimination (e.g. SVM-recursive feature elimination, SVM-RFE) with stability ensuring strategies such as ensemble feature selection. This enables PAA to detect stable and reliable biomarker candidate panels. Availability and implementation: PAA is freely available (BSD 3-clause license) from http://www.bioconductor.org/packages/PAA/. Contact: michael.turewicz@rub.de or martin.eisenacher@rub.de PMID:26803161

  9. Disinfection of water in recirculating aquaculture systems with peracetic acid

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) has become a favoured alternative to chlorination in the disinfection of municipal waste water in recent years. It is also commonly used in the food industry as a disinfectant. Based on PAA concentration, the disulfide linkage in enzymes and proteins of microorganisms can be bro...

  10. The Physiological Significance of Phenylacetic Acid in Abscising Cotton Cotyledons

    PubMed Central

    Suttle, Jeffrey C.; Mansager, Eugene R.

    1986-01-01

    The physiological role of phenylacetic acid (PAA) as an endogenous regulator of cotyledon abscission was examined using cotton (Gossypium hirsutum L. cv LG 102) seedlings. Application of 100 micromolar or more PAA to leafless cotyledon abscission-zone explants resulted in the retardation of petiole abscission and a decrease in the rise of ethylene evolution that normally accompanies aging of these explants in vitro. The partial inhibition of ethylene evolution in these explants by PAA was indirect since application of this compound stimulated short-term (<24 hours) ethylene production. PAA treatment partially suppressed the stimulation of petiole abscission elicited by either ethylene or abscisic acid. Both free and an acid-labile, bound form of PAA were identified in extracts prepared from cotyledons. No discernible pattern of changes in free or bound PAA was found during the course of ethylene-induced cotyledon abscission. Unlike indole-3-acetic acid, transport of PAA in isolated petiole segments was limited and exhibited little polarity. On the whole, these results are not consistent with the direct participation of PAA in the endogenous regulation of cotyledon abscission. Images Fig. 2 PMID:16664834

  11. Controlling fungus on channel catfish eggs with peracetic acid

    USDA-ARS?s Scientific Manuscript database

    There is much interest in the use of peracetic acid (PAA) to treat pathogens in aquaculture. It is a relatively new compound and is approved for use in Europe, but not in the United States. This study determined the effectiveness of PAA for fungus control on channel catfish Ictalurus punctatus egg...

  12. Peracetic acid: the long road to introduction of this disinfectant into U.S. aquaculture

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) is a promising disinfectant for biosecurity in the US aquaculture industry to prevent disease outbreaks from fish pathogens. PAA is a stabilized mixture of acetic acid, hydrogen peroxide and water that breaks down quickly to water and vinegar. It has replaced chlorine in some ...

  13. Peracetic acid degradation in freshwater aquaculture systems and possible practical implications

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) is a highly reactive peroxygen compound with wide-ranging antimicrobial effects and is considered an alternative sanitizer to formaldehyde. Products containing PAA are available in solution with acetic acid and hydrogen peroxide to maintain the stability of the chemical, and it...

  14. Duration of the protective effect of polyaspartic acid on experimental gentamicin nephrotoxicity.

    PubMed Central

    Swan, S K; Gilbert, D N; Kohlhepp, S J; Leggett, J E; Kohnen, P W; Bennett, W M

    1992-01-01

    It is known that daily polyaspartic acid (PAA) protects the kidney from gentamicin nephrotoxicity in a standardized rat model despite marked cortical accumulation of the aminoglycoside. The present experiments address the duration of PAA protection. When administered every other day, PAA provided functional and histologic protection against gentamicin-induced toxicity. A stepwise reduction in nephroprotection occurred as the dosage interval was prolonged. PMID:1489205

  15. Pharmacologic limits of the protective effect of polyaspartic acid on experimental gentamicin nephrotoxicity.

    PubMed Central

    Swan, S K; Gilbert, D N; Kohlhepp, S J; Kohnen, P W; Bennett, W M

    1993-01-01

    Polyaspartic acid (PAA) ameliorates experimental gentamicin nephrotoxicity despite marked accumulation of gentamicin in the renal cortex. The experiments described here probe the extent of PAA's nephroprotective action when increasing doses of gentamicin, in excess of an established nephrotoxic dose (40 mg/kg of body weight per day), are administered. After 10 days, virtually complete nephroprotection was conferred by PAA coadministered to animals receiving three times the nephrotoxic dose (120 mg/kg/day) of gentamicin. PMID:8452369

  16. Characterization of calcium carbonate/chitosan composites

    SciTech Connect

    Gonsalves, K.E.; Zhang, S.

    1995-12-31

    The crystal growth of calcium carbonate on a chitosan substrate was achieved using a supersaturated calcium carbonate solution, by using various additives, polyacrylic acid (PAA). Polyacrylic acid modified the chitosan-film surface and promoted the nucleation of calcium carbonate crystals.

  17. Chitosan-decorated polystyrene-b-poly(acrylic acid) polymersomes as novel carriers for topical delivery of finasteride.

    PubMed

    Caon, Thiago; Porto, Ledilege Cucco; Granada, Andréa; Tagliari, Monika Piazzon; Silva, Marcos Antonio Segatto; Simões, Cláudia Maria Oliveira; Borsali, Redouane; Soldi, Valdir

    2014-02-14

    In view of the fact that the oral administration of finasteride (FIN) has resulted in various undesirable systemic side effects, the topical application of polystyrene and poly(acrylic acid)-based polymersomes (underexplored system) was investigated. Undecorated PS139-b-PAA17 and PS404-b-PAA63 vesicles (C3 and C7, respectively) or vesicles decorated with chitosan samples of different molecular weight (C3/CS-oligo, C7/CS-oligo, C3/CS-37 and C7/CS-37) were prepared by the co-solvent self-assembly method and characterized by small-angle X-ray scattering,transmission electron microscopy and dynamic light scattering techniques. In vitro release experiments and ex vivo permeation using Franz diffusion cells were carried out (through comparison with hydroethanolic finasteride solution). The ideal system should provide high finasteride retention in the dermis and epidermis while allowing some control of the drug release. The particle size and in vitro release were negatively correlated with the permeation coefficient and skin retention in both the epidermis and dermis. The findings that the longest lag time was obtained for the hydroethanolic drug solution and lowest permeation for the systems able to release the drug faster support the hypothesis that nanostructured systems may be required to enhance the penetration and permeation of the drug. Chitosan-decorated polymersomes interacted more strongly with the skin components than non-decorated samples, probably due to the positive surface charge, which increased the FIN retention and reduced the lag time. C7 polymersomes decorated with chitosan were more appropriate for topical applications (high retention in the dermis and epidermis and controlled drug delivery).

  18. Cytotoxicity and metal ions removal using antibacterial biodegradable hydrogels based on N-quaternized chitosan/poly(acrylic acid).

    PubMed

    Mohamed, Riham R; Elella, Mahmoud H Abu; Sabaa, Magdy W

    2017-05-01

    Physically crosslinked hydrogels resulted from interaction between N,N,N-trimethyl chitosan chloride (N-Quaternized Chitosan) (NQC) and poly(acrylic acid) (PAA) were synthesized in different weight ratios (3:1), (1:1) and (1:3) taking the following codes Q3P1, Q1P1 and Q1P3, respectively. Characterization of the mentioned hydrogels was done using several analysis tools including; FTIR, XRD, SEM, TGA, biodegradation in simulated body fluid (SBF) and cytotoxicity against HepG-2 liver cancer cells. FTIR results proved that the prepared hydrogels were formed via electrostatic and H-bonding interactions, while XRD patterns proved that the prepared hydrogels -irrespective to their ratios- were more crystalline than both matrices NQC and PAA. TGA results, on the other hand, revealed that Q1P3 hydrogel was the most thermally stable compared to the other two hydrogels (Q3P1 and Q1P1). Biodegradation tests in SBF proved that these hydrogels were more biodegradable than the native chitosan. Examination of the prepared hydrogels for their potency in heavy metal ions removal revealed that they adsorbed Fe (III) and Cd (II) ions more than chitosan, while they adsorbed Cr (III), Ni (II) and Cu (II) ions less than chitosan. Moreover, testing the prepared hydrogels as antibacterial agents towards several Gram positive and Gram negative bacteria revealed their higher antibacterial activity as compared with NQC when used alone. Evaluating the cytotoxic effect of these hydrogels on an in vitro human liver cancer cell model (HepG-2) showed their good cytotoxic activity towards HepG-2. Moreover, the inhibition rate increased with increasing the hydrogels concentration in the culture medium. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. PAA1, a P-Type ATPase of Arabidopsis, Functions in Copper Transport in Chloroplasts

    PubMed Central

    Shikanai, Toshiharu; Müller-Moulé, Patricia; Munekage, Yuri; Niyogi, Krishna K.; Pilon, Marinus

    2003-01-01

    Copper (Cu) is an essential trace element with important roles as a cofactor in many plant functions, including photosynthesis. However, free Cu ions can cause toxicity, necessitating precise Cu delivery systems. Relatively little is known about Cu transport in plant cells, and no components of the Cu transport machinery in chloroplasts have been identified previously. Cu transport into chloroplasts provides the cofactor for the stromal enzyme copper/zinc superoxide dismutase (Cu/ZnSOD) and for the thylakoid lumen protein plastocyanin, which functions in photosynthetic electron transport from the cytochrome b6f complex to photosystem I. Here, we characterized six Arabidopsis mutants that are defective in the PAA1 gene, which encodes a member of the metal-transporting P-type ATPase family with a functional N-terminal chloroplast transit peptide. paa1 mutants exhibited a high-chlorophyll-fluorescence phenotype as a result of an impairment of photosynthetic electron transport that could be ascribed to decreased levels of holoplastocyanin. The paa1-1 mutant had a lower chloroplast Cu content, despite having wild-type levels in leaves. The electron transport defect of paa1 mutants was evident on medium containing <1 μM Cu, but it was suppressed by the addition of 10 μM Cu. Chloroplastic Cu/ZnSOD activity also was reduced in paa1 mutants, suggesting that PAA1 mediates Cu transfer across the plastid envelope. Thus, PAA1 is a critical component of a Cu transport system in chloroplasts responsible for cofactor delivery to plastocyanin and Cu/ZnSOD. PMID:12782727

  20. Nickel adsorption by sodium polyacrylate-grafted activated carbon.

    PubMed

    Ewecharoen, A; Thiravetyan, P; Wendel, E; Bertagnolli, H

    2009-11-15

    A novel sodium polyacrylate grafted activated carbon was produced by using gamma radiation to increase the number of functional groups on the surface. After irradiation the capacity for nickel adsorption was studied and found to have increased from 44.1 to 55.7 mg g(-1). X-ray absorption spectroscopy showed that the adsorbed nickel on activated carbon and irradiation-grafted activated carbon was coordinated with 6 oxygen atoms at 2.04-2.06 A. It is proposed that this grafting technique could be applied to other adsorbents to increase the efficiency of metal adsorption.

  1. Long-term protection of polyaspartic acid in experimental gentamicin nephrotoxicity.

    PubMed Central

    Swan, S K; Kohlhepp, S J; Kohnen, P W; Gilbert, D N; Bennett, W M

    1991-01-01

    Polyaspartic Acid (PAA) protects the kidney from experimental gentamicin nephrotoxicity despite large increases in renal cortical gentamicin content. In these experiments, prominent cytoplasmic vacuoles were noted in all animals that received PAA with or without gentamicin. The present study showed that there were no renal structural or functional consequences of PAA given alone or with gentamicin for up to 14 days, followed by a 16-week washout period. Creatinine clearance was similar to that of controls in animals that received gentamicin and in those that received PAA alone. Thus, complete functional protection was conferred by PAA and gentamicin, confirming previous reports from our laboratory. There was no protection by PAA from the nephrotoxic effects of mercuric chloride and cis-platinum. PMID:1810193

  2. Effect of Polyelectrolyte and Fatty Acid Soap on the Formation of CaCO3 in the Bulk and the Deposit on Hard Surfaces.

    PubMed

    Wang, Hao; Alfredsson, Viveka; Tropsch, Juergen; Ettl, Roland; Nylander, Tommy

    2015-09-30

    The effects of sodium polyacrylate (NaPAA) as well as potassium oleate on the nucleation and calcium carbonate crystal growth on hard surfaces, i.e., stainless steel and silica, have been investigated at different temperatures. The relation between the surface deposition and the corresponding bulk processes has been revealed by combining dynamic light scattering (DLS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and ellipsometry. The aim was to further our understanding of the crystal deposition/growth mechanism and how it can be controlled by the presence of polyelectrolytes (NaPAA) or soap (potassium oleate). The addition of polyelectrolytes (NaPAA) or soap (potassium oleate) decreases the size of CaCO3 particles in bulk solution and affects both crystal structure and morphology in the bulk as well as on hard surfaces. The amount of particles on hard surfaces decreases significantly in the presence of both potassium oleate and NaPAA. This was found to be a consequence of potassium oleate or NaPAA adsorption on the hard surface as well as on the CaCO3 crystal surfaces. Here, the polymer NaPAA exhibited a stronger inhibition effect on the formation and growth of CaCO3 particles than potassium oleate.

  3. Evaluation of thirteen haloacetic acids and ten trihalomethanes formation by peracetic acid and chlorine drinking water disinfection.

    PubMed

    Xue, Runmiao; Shi, Honglan; Ma, Yinfa; Yang, John; Hua, Bin; Inniss, Enos C; Adams, Craig D; Eichholz, Todd

    2017-09-15

    Free chlorine is a commonly used disinfectant in drinking water treatment. However, disinfection by-products (DBPs) are formed during water disinfection. Haloacetic acids (HAAs) and trihalomethanes (THMs) are two major groups of DBPs. Iodo-HAAs and iodo-THMs (I-HAAs and I-THMs) are formed during the disinfection of the water containing high levels of iodide and are much more toxic than their chlorinated and brominated analogs. Peracetic acid (PAA) is a strong antimicrobial disinfectant that is expected to reduce the formation of HAAs and THMs during disinfection. In this study, the formations of thirteen HAAs and ten THMs, including the iodinated forms, have been investigated during PAA disinfection and chlorination as the comparison. The DBP formations under different iodide concentrations, pHs, and contact times were systematically investigated. Two types of commercial PAAs containing different concentrations of PAA and hydrogen peroxide (H2O2) were studied. A solid-phase microextraction gas chromatography-mass spectrometry method was upgraded for THM analysis including I-THMs. HAAs were analyzed by following a recently developed high performance ion chromatography-tandem mass spectrometry method. Results show that the ratio of PAA and H2O2 concentration significantly affect the formation of I-THMs and I-HAAs. During PAA disinfection with lower PAA than H2O2, no detectable levels of THMs and HAAs were observed. During PAA disinfection with higher PAA than H2O2, low levels of monoiodoacetic acid, diiodoacetic acid, and iodoform were formed, and these levels were enhanced with the increase of iodide concentration. No significant quantities of chloro- or bromo-THMs and HAAs were formed during PAA disinfection treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Synthesis of N-vinylpyrrolidone modified acrylic acid copolymer in supercritical fluids and its application in dental glass-ionomer cements.

    PubMed

    Moshaverinia, Alireza; Roohpour, Nima; Billington, Richard W; Darr, Jawwad A; Rehman, Ihtesham U

    2008-07-01

    Compressed fluids such as supercritical CO(2) offer marvellous opportunities for the synthesis of polymers, particularly in applications in medicine and dentistry. It has several advantages in comparison to conventional polymerisation solvents, such as enhanced kinetics and simplified solvent removal process. In this study, poly(acrylic acid-co-itaconic acid-co-N-vinylpyrrolidone) (PAA-IA-NVP), a modified glass-ionomer polymer, was synthesised in supercritical CO(2) (sc-CO(2)) and methanol as a co-solvent. The synthesised polymer was characterized by (1)H-NMR, Raman and FT-IR spectroscopy and viscometry. The molecular weight of the final product was also measured using static light scattering method. The synthesised polymers were subsequently used in several glass ionomer cement formulations (Fuji II commercial GIC) in which mechanical strength (compressive strength (CS), diametral tensile strength (DTS) and biaxial flexural strength (BFS)) and handling properties (working and setting time) of the resulting cements were evaluated. The polymerisation reaction in sc-CO(2)/methanol was significantly faster than the corresponding polymerisation reaction in water and the purification procedures were simpler for the former. Furthermore, glass ionomer cement samples made from the terpolymer prepared in sc-CO(2)/methanol exhibited higher CS and DTS and comparable BFS compared to the same polymer synthesised in water. The working properties of glass ionomer formulations made in sc-CO(2)/methanol were comparable and in selected cases better than the values of those made from polymers synthesised in water.

  5. Mechanism of Concentration Dependence of Water Diffusivity in Polyacrylate Gels

    NASA Astrophysics Data System (ADS)

    Mani, Sriramvignesh; Khabaz, Fardin; Khare, Rajesh

    Membrane based separation processes offer an energy efficient alternative to traditional distillation based separation processes. In this work, we focus on the molecular mechanisms underlying the process of separation of dilute ethanol-water mixture using polyacrylate gels as pervaporation membranes. The diffusivities of the components in swollen gels exhibit concentration dependence. We have used molecular dynamics (MD) simulations to study the correlation between the dynamics of solvent (water and ethanol) molecules, polymer dynamics and solvent structure in the swollen gel systems as a function of solvent concentration. Three different polyacrylate gels were studied: (1) poly n-butyl acrylate (PBA), (2) copolymer of butyl acrylate and 2-hydroxyethyl acrylate P(BA50-HEA50), and (3) poly 2-hydroxyethyl acrylate (PHEA). Simulation results show that solvent concentration has a significant effect on local structure of the solvent molecules and chain dynamics; these factors (local structure and chain dynamics), in turn, affect the diffusivity of these molecules. At low concentration, solvent molecules are well dispersed in the gel matrix and form hydrogen bonds with the polymer. Solvent mobility is correlated with polymer mobility in this configuration and consequently water and ethanol molecules exhibit slower dynamics, this effect is especially significant in PHEA gel. At high solvent concentration, water molecules form large clusters in the system accompanied by enhancement in mobility of both the gel network and the solvent molecules.

  6. Biodegradability of a polyacrylate superabsorbent in agricultural soil.

    PubMed

    Wilske, Burkhard; Bai, Mo; Lindenstruth, Beate; Bach, Martin; Rezaie, Zahra; Frede, Hans-Georg; Breuer, Lutz

    2014-01-01

    Superabsorbent polymers (SAP) are used, inter alia, as soil amendment to increase the water holding capacity of soils. Biodegradability of soil conditioners has become a desired key characteristic to protect soil and groundwater resources. The present study characterized the biodegradability of one acrylate based SAP in four agricultural soils and at three temperatures. Mineralisation was measured as the (13)CO₂ efflux from (13)C-labelled SAP in soil incubations. The SAP was either single-labelled in the carboxyl C-atom or triple-labelled including additionally the two C-atoms interlinked in the SAP backbone. The dual labelling allowed estimating the degradation of the polyacrylate main chain. The (13)CO₂ efflux from samples was measured using an automated system including wavelength-scanned cavity ring-down spectroscopy. Based on single-labelled SAP, the mean degradation after 24 weeks varied between 0.45% in loamy sand and 0.82% in loam. However, the differences between degradation rates in different soils were not significant due to a large intra-replicate variability. Similarly, mean degradation did not differ significantly between effective temperature regimes of 20° and 30 °C after 12 weeks. Results from the triple-labelled SAP were lower as compared to their single-labelled variant. Detailed results suggest that the polyacrylate main chain degraded in the soils, if at all, at rates of 0.12-0.24 % per 6 months.

  7. Induction of mesenchymal stem cell chondrogenesis by polyacrylate substrates.

    PubMed

    Glennon-Alty, Laurence; Williams, Rachel; Dixon, Simon; Murray, Patricia

    2013-04-01

    Mesenchymal stem cells (MSCs) can generate chondrocytes in vitro, but typically need to be cultured as aggregates in the presence of transforming growth factor beta (TGF-β), which makes scale-up difficult. Here we investigated if polyacrylate substrates modelled on the functional group composition and distribution of the Arg-Gly-Asp (RGD) integrin-binding site could induce MSCs to undergo chondrogenesis in the absence of exogenous TGF-β. Within a few days of culture on the biomimetic polyacrylates, both mouse and human MSCs, and a mesenchymal-like mouse-kidney-derived stem cell line, began to form multi-layered aggregates and started to express the chondrocyte-specific markers, Sox9, collagen II and aggrecan. Moreover, collagen II tended to be expressed in the centre of the aggregates, similarly to developing limb buds in vivo. Surface analysis of the substrates indicated that those with the highest surface amine content were most effective at promoting MSC chondrogenesis. These results highlight the importance of surface group functionality and the distribution of those groups in the design of substrates to induce MSC chondrogenesis.

  8. [Predicting the cadmium bioavailability in the soil of sugarcane field based on the diffusive gradients in thin films with binding phase of sodium polyacrylate].

    PubMed

    Wang, Fang-Li; Song, Ning-Ning; Zhao, Yu-Jie; Zhang, Chang-Bo; Shen, Yue; Liu, Zhong-Qi

    2012-10-01

    The diffusive gradients in thin films (DGT) technique with solid-state binding phases has been widely used for in situ collection and measurement of available heavy metals in waters, soils or sediments, whereas DGT with liquid binding phase is primarily used in the in situ analysis of heavy metals in waters. In this paper, rhizosphere soils of sugarcane were collected in Guangxi and the concentrations of cadmium (Cd) were determined by DGT with a solid-state binding phase of chelex100 (chelex100-DGT) and modified DGT with a liquid binding phase of sodium polyacrylate (CDM-PAAS-DGT). The result showed that the Cd contents in soils measured by DGT with both binding phases and Cd in the roots, leaves and unpolished stems of sugarcane had significant positive correlation. The extraction ability of the CDM-PAAAS-DGT was much higher than that of the chelex100-DGT. In addition, multivariate analyses were used to assess the impact of pH, cation exchange capacity (CEC), soil organic matter (OM) and texture. Two principal components were extracted and the linear regression models were established. The Cd bioavailability in soils could be accurately predicted by the CDM-PAAAS-DGT technique, which expanded its applicable area.

  9. Pre/post-strike atmospheric assessment system (PAAS)

    SciTech Connect

    Peglow, S. G., LLNL; Molitoris, J. D., LLNL

    1997-02-03

    The Pre/Post-Strike Atmospheric Assessment System was proposed to show the importance of local meteorological conditions in the vicinity of a site suspected of storing or producing toxic agents and demonstrate a technology to measure these conditions, specifically wind fields. The ability to predict the collateral effects resulting from an attack on a facility containing hazardous materials is crucial to conducting effective military operations. Our study approach utilized a combination of field measurements with dispersion modeling to better understand which variables in terrain and weather were most important to collateral damage predictions. To develop the PAAS wind-sensing technology, we utilized a combination of emergent and available technology from micro-Doppler and highly coherent laser systems. The method used for wind sensing is to probe the atmosphere with a highly coherent laser beam. As the beam probes, light is back-scattered from particles entrained in the air to the lidar transceiver and detected by the instrument. Any motion of the aerosols with a component along the beam axis leads to a Doppler shift of the received light. Scanning in a conical fashion about the zenith results in a more accurate and two-dimensional measurement of the wind velocity. The major milestones in the benchtop system development were to verify the design by demonstrating the technique in the laboratory, then scale the design down to a size consistent with a demonstrator unit which could be built to take data in the field. The micro-Doppler heterodyne system we developed determines absolute motion by optically mixing a reference beam with the return signal and has shown motion sensitivity to better than 1 cm/s. This report describes the rationale, technical approach and laboratory testing undertaken to demonstrate the feasibility and utility of a system to provide local meteorological data and predict atmospheric particulate motion. The work described herein was funded by

  10. Pulse vs. continuous treatment: which is better for applying peracetic acid in RAS?

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) is a promising disinfectant in aquaculture. It is highly effective against various fish pathogens and also environmentally friendly due to harmless degradation residues. However, knowledge about potential adverse effects of PAA disinfection on fish is lacking; practical guidelin...

  11. MUTAGENICITY AND DISINFECTION BY-PRODUCTS IN SURFACE DRINKING WATER DISINFECTED WITH PERACETIC ACID

    EPA Science Inventory

    The aims of this research were to study the influence of peracetic acid (PAA) on the formation of mutagens in surface waters used for human consumption and to assess its potential application for the disinfection of drinking water. The results obtained using PAA were compared to ...

  12. Peracetic acid is effective for controlling fungus on channel catfish eggs

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA) is a relatively new compound suggested for use to treat pathogens in aquaculture. It is approved for use in Europe, but not in the United States. This study determined the effectiveness of PAA for fungus control on channel catfish Ictalurus punctatus eggs. The study consisted...

  13. MUTAGENICITY AND DISINFECTION BY-PRODUCTS IN SURFACE DRINKING WATER DISINFECTED WITH PERACETIC ACID

    EPA Science Inventory

    The aims of this research were to study the influence of peracetic acid (PAA) on the formation of mutagens in surface waters used for human consumption and to assess its potential application for the disinfection of drinking water. The results obtained using PAA were compared to ...

  14. Determination of superabsorbent polyacrylate dust in workplace atmospheres after derivatization with ethanol and using HPLC with pulsed electrochemical detection.

    PubMed

    Wink, O; Schack, F

    2000-10-01

    Superabsorbent polyacrylates (SAPs) have been used in the hygiene industry for many years. A derivatization and analytical method was developed for routine analysis of trace levels of SAP dust in workplace atmospheres. In comparison with existing methods, which are based on the sodium content or the ion exchange properties of the polymer, this method is more specific. It has the advantage of not being influenced by any sodium containing contaminants. Air samples are collected on Teflon filters using air monitoring sampling cassettes. The filters are subsequently placed in quartz vials and a reaction mixture containing hydrochloric acid in ethanol is added. The hydrochloric acid-ethanol solution, when heated, converts the carboxylic acid groups on the backbone of the insoluble polyacrylate into ethyl esters. After reaction, the excess of ethanol and hydrochloric acid is completely removed under vacuum. The sample is then treated with aqueous sodium hydroxide at 80 degrees C to release the bound ethanol. The solution is analyzed by HPLC on an anion exclusion stationary phase using dilute perchloric acid as mobile phase. Ethanol is identified and quantified with a pulsed electrochemical detector. Several environmental samples in addition to laboratory spiked samples were successfully analyzed with this technique. Recoveries averaged > 85% for spiked blank filters at levels from 5 to 50 micrograms per filter with relative standard deviations up to 7%. The instrument's limit of detection (LOD) for ethanol was 0.1 mg l-1. The LOD for derivatization and analysis corresponds to 3 micrograms of SAP per filter (assuming an esterification factor of 0.30 microgram of ethanol per microgram of SAP).

  15. PAA-PAMPS copolymers as an efficient tool to control CaCO3 scale formation.

    PubMed

    Dietzsch, Michael; Barz, Matthias; Schüler, Timo; Klassen, Stefanie; Schreiber, Martin; Susewind, Moritz; Loges, Niklas; Lang, Michael; Hellmann, Nadja; Fritz, Monika; Fischer, Karl; Theato, Patrick; Kühnle, Angelika; Schmidt, Manfred; Zentel, Rudolf; Tremel, Wolfgang

    2013-03-05

    Scale formation, the deposition of certain minerals such as CaCO3, MgCO3, and CaSO4·2H2O in industrial facilities and household devices, leads to reduced efficiency or severe damage. Therefore, incrustation is a major problem in everyday life. In recent years, double hydrophilic block copolymers (DHBCs) have been the focus of interest in academia with regard to their antiscaling potential. In this work, we synthesized well-defined blocklike PAA-PAMPS copolymers consisting of acrylic acid (AA) and 2-acrylamido-2-methyl-propane sulfonate (AMPS) units in a one-step reaction by RAFT polymerization. The derived copolymers had dispersities of 1.3 and below. The copolymers have then been investigated in detail regarding their impact on the different stages of the crystallization process of CaCO3. Ca(2+) complexation, the first step of a precipitation process, and polyelectrolyte stability in aqueous solution have been investigated by potentiometric measurements, isothermal titration calorimetry (ITC), and dynamic light scattering (DLS). A weak Ca(2+) induced copolymer aggregation without concomitant precipitation was observed. Nucleation, early particle growth, and colloidal stability have been monitored in situ with DLS. The copolymers retard or even completely suppress nucleation, most probably by complexation of solution aggregates. In addition, they stabilize existing CaCO3 particles in the nanometer regime. In situ AFM was used as a tool to verify the coordination of the copolymer to the calcite (104) crystal surface and to estimate its potential as a growth inhibitor in a supersaturated CaCO3 environment. All investigated copolymers instantly stopped further crystal growth. The carboxylate richest copolymer as the most promising antiscaling candidate proved its enormous potential in scale inhibition as well in an industrial-filming test (Fresenius standard method).

  16. Xylitol production from rice straw hemicellulose hydrolyzate by polyacrylic hydrogel thin films with immobilized Candida subtropicalis WF79.

    PubMed

    Liaw, Wen-Chang; Chen, Chee-Shan; Chang, Wen-Shion; Chen, Kuan-Pin

    2008-02-01

    Xylose from rice straw hemicellulose hydrolysate was fermented for xylitol production using Candida subtropicalis WF79 cells immobilized in polyacrylic hydrogel thin films of 200 mum thickness. Cell immobilization was conducted by first suspending the yeast cells in a mixture of 2-hydroxyethyl methacrylate (HEMA, hydrophilic monomer), polyethylene glycol diacrylate (PEG-DA, crosslinking agent), and benzoin isopropyl ether (photoinitiator). The mixture was then allowed to form polyacrylic hydrogel thin films, between two pieces of glass sheets, by UV-initiated photopolymerization. The hemicellulose of rice straw was hydrolyzed using dilute sulfuric acid at 126 degrees C. The hydrolysate was neutralized with calcium hydroxide. After separating the solid residues and calcium sulfate precipitates by filtration, the hydrolysate was treated with charcoal to partially remove potential inhibitory substances, followed by vacuum concentration to obtain solutions of desired xylose concentrations for yeast fermentation. The thin films with immobilized yeast cells were submerged in the xylose solution from rice straw hydrolysate for fermentation in an Erlenmeyer flask. The maximum yield was 0.73 g of xylitol per gram of xylose consumed. In the 52.5-day long durability test, after 40 d of repeated batchwise operation, the fermentation activities of the cell immobilized in thin films began to decline to a yield of 0.57 g/g at the end.

  17. Using polyacrylate-coated SPME fibers to quantify sorption of polar and ionic organic contaminants to dissolved organic carbon.

    PubMed

    Haftka, Joris J-H; Scherpenisse, Peter; Jonker, Michiel T O; Hermens, Joop L M

    2013-05-07

    A passive sampling method using polyacrylate-coated solid-phase microextraction (SPME) fibers was applied to determine sorption of polar and ionic organic contaminants to dissolved organic carbon (DOC). The tested contaminants included pharmaceuticals, industrial chemicals, hormones, and pesticides and represented neutral, anionic, and cationic structures. Prior to the passive sampler application, sorption of the chemicals to the fibers was characterized. This was needed in order to accurately translate concentrations measured in fibers to freely dissolved aqueous concentrations during the sorption tests with DOC. Sorption isotherms of neutral compounds to the fiber were linear, whereas isotherms of basic chemicals covered a nonlinear and a linear range. Sorption of acidic and basic compounds to the fiber was pH-dependent and was dominated by sorption of the neutral sorbate species. Fiber- and DOC-water partition coefficients of neutral compounds were both linearly related to octanol-water partition coefficients (log Kow). The results of this study show that polyacrylate fibers can be used to quantify sorption to DOC of neutral and ionic contaminants, having multiple functional groups and spanning a wide hydrophobicity range (log Kow = 2.5-7.5).

  18. Mechanism of Bacillus subtilis Spore Inactivation by and Resistance to Supercritical CO2 plus Peracetic Acid

    PubMed Central

    Setlow, Barbara; Korza, George; Blatt, Kelly M.S.; Fey, Julien P.; Setlow, Peter

    2015-01-01

    Aims Determine how supercritical CO2 (scCO2) plus peracetic acid (PAA) inactivates Bacillus subtilis spores, factors important in spore resistance to scCO2-PAA, and if spores inactivated by scCO2-PAA are truly dead. Methods and Results Spores of wild-type B. subtilis and isogenic mutants lacking spore protective proteins were treated with scCO2-PAA in liquid or dry at 35°C. Wild-type wet spores (aqueous suspension) were more susceptible than dry spores. Treated spores were examined for viability (and were truly dead), dipicolinic acid (DPA), mutations, permeability to nucleic acid stains, germination under different conditions, energy metabolism and outgrowth. ScCO2-PAA-inactivated spores retained DPA, and survivors had no notable DNA damage. However, DPA was released from inactivated spores at a normally innocuous temperature (85°C), and colony formation from treated spores was salt sensitive. The inactivated spores germinated but did not outgrow, and these germinated spores had altered plasma membrane permeability and defective energy metabolism. Wet or dry coat-defective spores had increased scCO2-PAA sensitivity, and dry spores but not wet spores lacking DNA protective proteins were more scCO2-PAA sensitive. Conclusions These findings suggest that scCO2-PAA inactivates spores by damaging spores’ inner membrane. The spore coat provided scCO2-PAA resistance for both wet and dry spores. DNA protective proteins provided scCO2-PAA resistance only for dry spores. Significance and Impact of Study These results provide information on mechanisms of spore inactivation of and resistance to scCO2-PAA, an agent with increasing use in sterilization applications. PMID:26535794

  19. Mechanism of Bacillus subtilis spore inactivation by and resistance to supercritical CO2 plus peracetic acid.

    PubMed

    Setlow, B; Korza, G; Blatt, K M S; Fey, J P; Setlow, P

    2016-01-01

    Determine how supercritical CO2 (scCO2 ) plus peracetic acid (PAA) inactivates Bacillus subtilis spores, factors important in spore resistance to scCO2 -PAA, and if spores inactivated by scCO2 -PAA are truly dead. Spores of wild-type B. subtilis and isogenic mutants lacking spore protective proteins were treated with scCO2 -PAA in liquid or dry at 35°C. Wild-type wet spores (aqueous suspension) were more susceptible than dry spores. Treated spores were examined for viability (and were truly dead), dipicolinic acid (DPA), mutations, permeability to nucleic acid stains, germination under different conditions, energy metabolism and outgrowth. ScCO2 -PAA-inactivated spores retained DPA, and survivors had no notable DNA damage. However, DPA was released from inactivated spores at a normally innocuous temperature (85°C), and colony formation from treated spores was salt sensitive. The inactivated spores germinated but did not outgrow, and these germinated spores had altered plasma membrane permeability and defective energy metabolism. Wet or dry coat-defective spores had increased scCO2 -PAA sensitivity, and dry spores but not wet spores lacking DNA protective proteins were more scCO2 -PAA sensitive. These findings suggest that scCO2 -PAA inactivates spores by damaging spores' inner membrane. The spore coat provided scCO2 -PAA resistance for both wet and dry spores. DNA protective proteins provided scCO2 -PAA resistance only for dry spores. These results provide information on mechanisms of spore inactivation of and resistance to scCO2 -PAA, an agent with increasing use in sterilization applications. © 2015 The Society for Applied Microbiology.

  20. Oxidation of β-lactam antibiotics by peracetic acid: Reaction kinetics, product and pathway evaluation.

    PubMed

    Zhang, Kejia; Zhou, Xinyan; Du, Penghui; Zhang, Tuqiao; Cai, Meiquan; Sun, Peizhe; Huang, Ching-Hua

    2017-10-15

    Peracetic acid (PAA) is a disinfection oxidant used in many industries including wastewater treatment. β-Lactams, a group of widely prescribed antibiotics, are frequently detected in wastewater effluents and surface waters. The reaction kinetics and transformation of seven β-lactams (cefalexin (CFX), cefadroxil (CFR), cefapirin (CFP), cephalothin (CFT), ampicillin (AMP), amoxicillin (AMX) and penicillin G (PG)) toward PAA were investigated to elucidate the behavior of β-lactams during PAA oxidation processes. The reaction follows second-order kinetics and is much faster at pH 5 and 7 than at pH 9 due to speciation of PAA. Reactivity to PAA follows the order of CFR ∼ CFX > AMP ∼ AMX > CFT ∼ CFP ∼ PG and is related to β-lactam's nucleophilicity. The thioether sulfur of β-lactams is attacked by PAA to generate sulfoxide products. Presence of the phenylglycinyl amino group on β-lactams can significantly influence electron distribution and the highest occupied molecular orbital (HOMO) location and energy in ways that enhance the reactivity to PAA. Reaction rate constants obtained in clean water matrix can be used to accurately model the decay of β-lactams by PAA in surface water matrix and only slightly overestimate the decay in wastewater matrix. Results of this study indicate that the oxidative transformation of β-lactams by PAA can be expected under appropriate wastewater treatment conditions. Copyright © 2017. Published by Elsevier Ltd.

  1. Growth inhibition of Aeromonas salmonicida and Yersinia ruckeri by disinfectants containing peracetic acid.

    PubMed

    Meinelt, Thomas; Phan, Thy-My; Behrens, Sascha; Wienke, Andreas; Pedersen, Lars-Flemming; Liu, Dibo; Straus, David L

    2015-04-08

    Peracetic acid (PAA) is a therapeutic agent used for disinfection in aquaculture, but it must be investigated thoroughly in order to mitigate diseases without harming the fish. Successful disinfectants (like PAA) should not leave dangerous residues in the environment in order to successfully contribute to sustainable aquaculture. The aim of our study was to compare the effectiveness of 6 commercial PAA products with different molecular PAA:H2O2 ratios to reduce bacterial growth of Aeromonas salmonicida and Yersinia ruckeri and to determine effective concentrations and exposure times. All products reduced colony-forming units (CFUs) of A. salmonicida and Y. ruckeri. Products with higher molecular PAA:H2O2 ratios inhibited growth better than products with lower molecular PAA:H2O2 ratios at the same PAA concentration; this indicates that H2O2 is not the driving force in the reduction of A. salmonicida and Y. ruckeri growth by PAA in vitro. The practical application of the products with high molecular PAA:H2O2 ratios should be prioritized if these pathogens are diagnosed.

  2. [Efficient killing of anthrax spores using aqueous and alcoholic peracetic acid solutions].

    PubMed

    Nattermann, H; Becker, S; Jacob, D; Klee, S R; Schwebke, I; Appel, B

    2005-08-01

    We analysed the sporicidal effect of different concentrations of aqueous and alcoholic peracetic acid (PAA) solutions on anthrax spores in suspension and germ carrier tests. In activation of anthrax spores in suspension assays was achieved in less than 2 min using 1% PAA solution and in less than 3 min using 0.5% PAA solution, respectively. In contrast, in germ carrier as says, a test under practical conditions, spores on 38% of the germ carriers survived treatment with 1% PAA solution for 15 min. The use of PAA in 80% ethyl alcohol outclassed the sporicidal effect of aqueous PAA solutions in both suspension and germ carrier assays. Anthrax spores on 14% of germ carriers tested survived 30 min of treatment with a 1% aqueous PAA solution. In contrast anthrax spores were reliably inactivated under the same test procedure using a 1% alcoholic PAA solution for 30 min. The proven enhancement of the sporicidal effect of alcoholic PAA solutions should be kept in mind when using disinfectants in practice. In further surveys we will optimise the test conditions.

  3. Thermal performance study of form-stable composite phase change material with polyacrylic

    NASA Astrophysics Data System (ADS)

    Kee, Shin Yiing; Munusamy, Yamuna; Ong, Kok Seng; Chee, Swee Yong; Sanmuggam, Shimalaa

    2017-04-01

    Phase change material (PCM) is one of the most popular and widely used as thermal energy storage material because it is able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. In this work, the form-stable composite PCM was prepared by blending of PMMA and myristic acid in different weight percentage. PMMA was used as a supporting material while myristic acid was used as PCM. Theoretically, PCM can be encapsulated in the support material after blending. However, a small amount of liquid PCMs can leak out from supporting material due to the volume change in phase change process. Therefore, a form-stable composite PCM with polyacrylic coating was studied. Leakage test was carried out to determine the leakage percentage of the form-stable composite PCM. Fourier transform infrared spectroscopy (FTIR) was used to characterize the chemical compatibility of the form-stable PCM composite while differential scanning calorimetry (DSC) was used to study the melting, freezing point and the latent heat of melting and freezing for the form-stable composite PCM.

  4. Functionalized gold nanorod solution via reverse micelle based polyacrylate coating.

    PubMed

    Basiruddin, S K; Saha, Arindam; Pradhan, Narayan; Jana, Nikhil R

    2010-05-18

    Functionalization of gold nanorods is a key issue for their biomedical application, and currently it is performed via either electrostatic interaction or thiol based strategy. We have developed a polyacrylate based coating chemistry for gold nanorods that can be used in deriving a variety of functional nanorods with high colloidal stability. The coating processes can introduce primary amines, fluorescein, or poly(ethylene glycol) (PEG) on the nanorod surface in one step process. While fluorescein incorporation can produce fluorescent nanorods, primary amine groups can be used for further functionalization. Various functional nanorods have been successfully synthesized from these coated nanorods and used in different applications. Glucose and biotin functionalized nanorods are used for protein detection, and oleyl functionalized nanorods with fluorescein incorporated in the polymer shell are used for fluorescence based cell labeling.

  5. Polyacrylate microspheres composite for all-solid-state reference electrodes.

    PubMed

    Kisiel, Anna; Donten, Mikołaj; Mieczkowski, Józef; Rius-Ruiz, F Xavier; Maksymiuk, Krzysztof; Michalska, Agata

    2010-09-01

    A novel concept is proposed for the encapsulation of components within polyacrylate microspheres, prior to their incorporation into a membrane phase. Thus finer and better controlled dispersion of heterogeneous membrane components can be achieved. This concept was verified by using a poly(n-butyl acrylate) membrane-based reference electrode as an example. In this example the proper dispersion of solid constituents of the heterogeneous membrane and prevention of their leakage are both of primary importance. Potassium chloride-loaded poly(n-butyl acrylate) microspheres were prepared and then left in contact with silver nitrate to convert some of the KCl into AgCl. The material obtained was introduced into a poly(n-butyl acrylate) membrane. The reference electrode membranes obtained in this way were characterized with much more stable potential (both in different electrolytes and over time) compared with electrodes prepared by the direct introduction of KCl and AgCl to the membrane.

  6. Oral vaccination against diphtheria using polyacryl starch microparticles as adjuvant.

    PubMed

    Rydell, Niclas; Sjöholm, Ingvar

    2004-03-12

    Oral vaccination offers the advantage of eliciting both a mucosal and a systemic immune response. This study investigated the use of polyacryl starch microparticles as adjuvant for oral vaccination against diphtheria. Diphtheria toxin or cross-reacting material (CRM197) were covalently conjugated to the microparticles and fed to mice by oral gavage. Investigation of formaldehyde treatment as a means of either detoxifying (diphtheria toxin) or stabilising (CRM197) these formulations were also made. We show that all our formulations given orally or parenterally to mice induced a strong systemic immune response. Only formulations given orally induced a mucosal IgA-response. Furthermore, our formulations given parenterally or orally induced a strong diphtheria toxin-neutralising antibody response.

  7. A Molecular Imprinting Strategy Employing Polyelectrolyte Multilayers

    NASA Astrophysics Data System (ADS)

    Olugebefola, Solar C.

    2005-03-01

    Polyelectrolyte multilayers were assembled from poly(allylamine hydrochloride) (PAH), poly(acrylic acid) (PAA) and poly(acrylic acid-r-vinyl benzyl acetate) (xPAA), derivatized from PAA. The pHs of polymer assembly solutions were controlled to yield high surface area film morphologies for adsorption. Assembled films were photo crosslinked in the presence of adsorbed template molecules and the template removed to yield selective binding sites. Quartz crystal microbalance measurements of adsorption onto films templated with bovine serum albumin show higher affinity for BSA compared to films crosslinked with no templating.

  8. Research on the chemical mechanism in the polyacrylate latex modified cement system

    SciTech Connect

    Wang, Min; Wang, Rumin; Zheng, Shuirong; Farhan, Shameel; Yao, Hao; Jiang, Hao

    2015-10-15

    In this paper, the chemical mechanism in the polyacrylate latex modified cement system was investigated by Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), gel permeation chromatography (GPC) and compact pH meter. All results have shown that the chemical reactions in the polyacrylate modified system can be divided into three stages. The hydration reactions of cement can produce large amounts of Ca(OH){sub 2} (calcium hydroxide) and lead the whole system to be alkali-rich and exothermic at the first stage. Subsequently, this environment can do great contributions to the hydrolysis of ester groups in the polyacrylate chains, resulting in the formation of carboxyl groups at the second stage. At the third stage, the final crosslinked network structure of the product was obtained by the reaction between the carboxyl groups in the polyacrylate latex chains and Ca(OH){sub 2}.

  9. Crystal growth vs. conventional acid etching: a comparative evaluation of etch patterns, penetration depths, and bond strengths.

    PubMed

    Devanna, Raghu; Keluskar, K M

    2008-01-01

    The present study was undertaken to investigate the effect on enamel surface, penetration depth, and bond strength produced by 37% phosphoric acid and 20% sulfated polyacrylic acid as etching agents for direct bonding. Eighty teeth were used to study the efficacy of the etching agents on the enamel surface, penetration depth, and tensile bond strength. It was determined from the present study that a 30 sec application of 20% sulfated polyacrylic acid produced comparable etching topography with that of 37% phosphoric acid applied for 30 sec. The 37% phosphoric acid dissolves enamel to a greater extent than does the 20% sulfated polyacrylic acid. Instron Universal testing machine was used to evaluate the bond strengths of the two etching agents. Twenty percent sulfated polyacrylic acid provided adequate tensile bond strength. It was ascertained that crystal growth can be an alternative to conventional phosphoric acid etching as it dissolves lesser enamel and provides adequate tensile bond strength.

  10. Synthesis and photoluminescence enhancement of nano-PAA-ZnCl2 with controllable dimension and morphology

    NASA Astrophysics Data System (ADS)

    Wu, Jianguo; Wang, Kaige; Zhou, Yukun; Wang, Shuang; Zhang, Chen; Wang, Guiren; Bai, Jintao

    2016-12-01

    One kind of ZnCl2 nano-films with controllable dimension and morphology is successfully synthesized on the top surface of nano-porous anodic alumina membrane (nano-PAAM) by self-organized method. The nano-PAA-ZnCl2 composite films are characterized by field emission scanning electron microscopy, energy dispersive spectrometer, and laser confocal Raman spectroscopy. The results indicate that the concentration of initial ZnCl2 solution, the depth of nano-PAAM substrate and the growth time of ZnCl2 crystals have important influences on the properties of nano-composite films. Furthermore, the characteristics of nano-composites such as the photoluminescence (PL) spectra are investigated. Compared with the nano-PAAM substrate, at room temperature, all of the nano-PAA-ZnCl2 composite films have both the same excitation center (335 nm) and emission center (430 nm), no matter what the nano-composite morphologies being; and the PL intensity of nano-PAA-ZnCl2 composite films are all enhanced and the maximum enhancement is two times; after annealing at 500 °C, the emission spectra of the nano-composite films stabilized at the 385 nm, 402 nm and 430 nm. The research provides a new, simple, economical and practical technology to fabricate nano-PAA composite films with higher luminousintensity.

  11. pH-Triggered SERS via Modulated Plasmonic Coupling in Individual Bimetallic Nanocobs

    DTIC Science & Technology

    2011-01-01

    dry states. In contrast with previous examples of such bimetallic nano- cobs, we utilize here a responsive polyacrylic acid (PAA) nanocoating that...acts as a linker between the nanoparticles and nanowire. [ 37 ] The pH-responsive nature of the PAA nanocoating , which is sensitive to the...indicating that pH-induced changes in the wet PAA nanocoating are robust enough to maintain changes in the optical properties and morphology even in

  12. The OH-initiated oxidation of atmospheric peroxyacetic acid: Experimental and model studies

    NASA Astrophysics Data System (ADS)

    Wu, Huihui; Wang, Yin; Li, Huan; Huang, Liubin; Huang, Dao; Shen, Hengqing; Xing, Yanan; Chen, Zhongming

    2017-09-01

    Peroxyacetic acid (PAA, CH3C(O)OOH) plays an important role in atmospheric chemistry, serving as reactive oxidant and affecting radical recycling. However, previous studies revealed an obvious gap between modelled and observed concentrations of atmospheric PAA, which may be partly ascribed to the uncertainty in the kinetics and mechanism of OH-oxidation. In this study, we measured the rate constant of OH radical reaction with PAA (kPAA+OH) and investigated the products in order to develop a more robust atmospheric PAA chemistry. Using the relative rates technique and employing toluene and meta-xylene as reference compounds, the kPAA+OH was determined to be (9.4-11.9) × 10-12 cm3 molecule-1 s-1 at 298 K and 1 atm, which is about (2.5-3.2) times larger than that parameter used in Master Chemical Mechanism v3.3.1 (MCM v3.3.1) (3.70 × 10-12 cm3 molecule-1 s-1). Incorporation of a box model and MCM v3.3.1 with revised PAA chemistry represented a better simulation of atmospheric PAA observed during Wangdu Campaign 2014, a rural site in North China Plain. It is found that OH-oxidation is an important sink of atmospheric PAA in this rural area, accounting for ∼30% of the total loss. Moreover, the major terminal products of PAA-OH reaction were identified as formaldehyde (HCHO) and formic acid (HC(O)OH). The modelled results show that both primary and secondary chemistry play an important role in the large HCHO and HC(O)OH formation under experimental conditions. There should exist the channel of methyl H-abstraction for PAA-OH reaction, which may also provide routes to HCHO and HC(O)OH formation.

  13. Temperature-induced collapse of alkaline Earth cation-polyacrylate anion complexes.

    PubMed

    Lages, Sebastian; Schweins, Ralf; Huber, Klaus

    2007-09-06

    Polyacrylate anions are used to inhibit CaCO3 precipitation and may be a promising additive to control formation of inorganic nanoparticles. The origin of this applicability lies in specific interactions between the alkaline earth cations and the carboxylate functions along the polyacrylate chains. In the absence of CO32- anions, these interactions eventually cause precipitation of polyelectrolytes. Extended investigation of dilute sodium polyacrylate solutions approaching this precipitation threshold revealed a dramatic shrinking of the PA coil dimensions once the threshold is reached (Eur. Phys. J. E 2001, 5, 117). Recent isothermal calorimetric titration experiments by Antonietti et al. (Macromolecules 2004, 37, 3444) indicated that the driving force of this precipitation is entropic in nature. In the present work, we investigated the impact of temperature on the structural changes of dissolved polyacrylate chains decorated with alkaline earth cations. To this end, large polyacrylate chains were brought close to the precipitation threshold by the addition of distinct amounts of Ca2+ or Sr2+ cations. The resulting structural intermediates were then subjected to temperature variations in the range of 15 degrees C polyacrylate coils were recorded by means of light and neutron scattering. As a major result, we could unambiguously demonstrate that the coils can reversibly be collapsed and extended by increasing and decreasing the temperature, respectively.

  14. Molecular modeling studies of interactions between sodium polyacrylate polymer and calcite surface

    NASA Astrophysics Data System (ADS)

    Ylikantola, A.; Linnanto, J.; Knuutinen, J.; Oravilahti, A.; Toivakka, M.

    2013-07-01

    The interactions between calcite pigment and sodium polyacrylate dispersing agent, widely used in papermaking as paper coating components, were investigated using classical force field and quantum chemical approaches. The objective was to understand interactions between the calcite surface and sodium polyacrylate polymer at 300 K using molecular dynamics simulations. A quantum mechanical ab initio Hartree-Fock method was also used to obtain detailed information about the sodium polyacrylate polymer structure. The effect of water molecules (moisture) on the interactions was also examined. Calculations showed that molecular weight, branching and the orientation of sodium polyacrylate polymers influence the interactions between the calcite surface and the polymer. The force field applied, and also water molecules, were found to have an impact on all systems studied. Ab initio Hartree-Fock calculations indicated that there are two types of coordination between sodium atoms and carboxylate groups of the sodium polyacrylate polymer, inter- and intra-carboxylate group coordination. In addition, ab initio Hartree-Fock calculations of the structure of the sodium polyacrylate polymer produced important information regarding interactions between the polymers and carboxylated styrene-butadiene latex particles.

  15. Salts of phenylacetic acid and 4-hydroxyphenylacetic acid with Cinchona alkaloids: Crystal structures, thermal analysis and FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Amombo Noa, Francoise M.; Jacobs, Ayesha

    2016-06-01

    Seven salts were formed with phenylacetic acid (PAA), 4-hydroxyphenylacetic acid (HPAA) and the Cinchona alkaloids; cinchonidine (CIND), quinidine (QUID) and quinine (QUIN). For all the structures the proton was transferred from the carboxylic acid of the PAA/HPAA to the quinuclidine nitrogen of the respective Cinchona alkaloid. For six of the salts, water was included in the crystal structures with one of these also incorporating an isopropanol solvent molecule. However HPAA co-crystallised with quinine to form an anhydrous salt, (HPAA-)(QUIN+). The thermal stability of the salts were determined and differential scanning calorimetry revealed that the (HPAA-)(QUIN+) salt had the highest thermal stability compared to the other salt hydrates. The salts were also characterized using Fourier transform infrared spectroscopy. (PAA-)(QUID+)·H2O and (PAA-)(QUIN+)·H2O are isostructural and Hirshfeld surface analysis was completed to compare the intermolecular interactions in these two structures.

  16. Styrene lower catabolic pathway in Pseudomonas fluorescens ST: identification and characterization of genes for phenylacetic acid degradation.

    PubMed

    Di Gennaro, Patrizia; Ferrara, Silvia; Ronco, Ilaria; Galli, Enrica; Sello, Guido; Papacchini, Maddalena; Bestetti, Giuseppina

    2007-08-01

    Pseudomonas fluorescens ST is a styrene degrading microorganism that, by the sequential oxidation of the vinyl side chain, converts styrene to phenylacetic acid. The cluster of styrene upper pathway catabolic genes (sty genes) has been previously localized on a chromosomal region. This report describes the isolation, sequencing and analysis of a new chromosomal fragment deriving from the ST strain genomic bank that contains the styrene lower degradative pathway genes (paa genes), involved in the metabolism of phenylacetic acid. Analysis of the paa gene cluster led to the description of 14 putative genes: a gene encoding a phenylacetyl-CoA ligase (paaF), the enzyme required for the activation of phenylacetic acid; five ORFs encoding the subunits of a ring hydroxylation multienzymatic system (paaGHIJK); the gene paaW encoding a membrane protein of unknown function; five genes for a beta-oxidation-like system (paaABCDE), involved in the steps following the aromatic ring cleavage; a gene encoding a putative permease (paaL) and a gene (paaN) probably involved in the aromatic ring cleavage. The function of some of the isolated genes has been proved by means of biotransformation experiments.

  17. Impact of sodium polyacrylate on the amorphous calcium carbonate formation from supersaturated solution.

    PubMed

    Liu, J; Pancera, S; Boyko, V; Gummel, J; Nayuk, R; Huber, K

    2012-02-21

    A detailed in situ scattering study has been carried out on the formation of amorphous calcium carbonate (ACC) particles modulated by the presence of small amounts of sodium polyacrylate chains. The work is aiming at an insight into the modulation of ACC formation by means of two polyacrylate samples differing in their molecular weight by a factor of 50. The ACC formation process was initiated by an in situ generation of CO(3)(2-) ions via hydrolysis of 10 mM dimethylcarbonate in the presence of 10 mM CaCl(2). Analysis of the formation process by means of time-resolved small-angle X-ray and light scattering in the absence of any additives provided evidence for a monomer addition mechanism for the growth of ACC particles. ACC formation under these conditions sets in after a lag-period of some 350 s. In the presence of sodium polyacrylate chains, calcium polyacrylate aggregates are formed during the lag-period, succeeded by a modulated ACC growth in a second step. The presence of anionic polyacrylate chains changed the shape of the growing particles toward loose and less homogeneous entities. In the case of low amounts (1.5-7.5 mg/L) of the long chain additive with 97 kDa, the size of the aggregates is comparable to the size of the successively formed hybrid particles. No variation of the lag-period has been observed in this case. Use of the short chain additive with 2 kDa enabled increase of the additive concentration up to 100 mg/L and resulted in a significant increase of the lag-period. This fact, together with the finding that the resulting hybrid particles remained stable in the latter case, identified short chain sodium polyacrylates as more efficient modulators than long chain polyacrylates.

  18. Low-Melt Polyamic Acid Based Powder Coatings

    NASA Technical Reports Server (NTRS)

    Jolley, Scott T. (Inventor)

    2017-01-01

    The present invention is directed to a method for powder coating a metal substrate using a low-melt polyamic acid (PAA) polymer that readily imidizes to polyimides. These low-melt PAAs have been shown to be useful in resins applied as powder coatings to metal surfaces. The resin includes an end-capping material capable of providing crosslinking functionality to at least one end of the low-melt PAA polymer. The end-capping material functions dually as a polymerization chain terminator and crosslinking agent, thus producing resins that have molecular weights low enough to flow well and form good cured films applicable for use in powder coating.

  19. Deswelling kinetics of polyacrylate gels in solutions of cetyltrimethylammonium bromide.

    PubMed

    Nilsson, Peter; Hansson, Per

    2007-08-23

    The deswelling kinetics of single sodium polyacrylate gel beads (radius 40-160 microm) in aqueous solutions of cetyltrimethylammonium bromide under conditions of forced convection are investigated using micromanipulator assisted light microscopy. The purpose of the study is to further evaluate a previously published model (J. Phys. Chem. B 2003, 107, 9203) using a higher homolog surfactant. For gels with expected fast deswelling (small gel size/low surfactant concentration) and/or in low electrolyte concentration, the model is found to correctly predict the deswelling characteristics of the gel beads. However, for some gels with expected slow deswelling, especially in high electrolyte concentration (10 mM NaBr), the model widely underestimates the required deswelling time. The reason for this is argued to be the longer time frame and high bromide concentration allowing the formation of a denser, more ordered structure in the surface phase, which resists the deformation and reorganization of material necessary for deswelling. Unexpectedly long lag times before the start of deswelling are also found for gels in low surfactant concentration, indicating that a relatively high surfactant concentration in the gel, greatly exceeding the critical aggregation concentration, is needed to start formation of a collapsed surface phase. This critical surfactant concentration is found to be dependent on initial gel radius, as small gels require a relatively higher concentration to initiate collapse.

  20. Effect of sodium polyacrylate on chronic reflux esophagitis in rats.

    PubMed

    Ishii, Y; Fujii, Y; Yamashita, T

    1981-01-01

    Sodium polyacrylate (PANa) is a high-molecular compound which makes a very viscous aqueous solution. It was reported that PANa has a preventive effect on spontaneous gastroesophageal ulceration in swine. In this study, the effect of PANa on the chronic reflux esophagitis in rats induced by total gastrectomy followed by esophagojejunostomy was investigated. Ulceration and hyperplasia began to develop in the esophageal region about 10 days after the operation. PANa was dissolved in drinking water and the rats were allowed free access to the solution. The development of ulceration and hyperplasia was significantly inhibited by the treatment with PANa in a dose-dependent manner (0.02-0.5%). Histological findings at 30 days after the operation indicated that PANa caused a significant inhibition of the ulceration and a significant acceleration of the regeneration of the mucosa. On the other hand, other viscous compounds such as sodium carboxymethyl cellulose and sodium alginate and a specific trypsin inhibitor such as leupeptin showed no significant inhibition against the esophagitis. The decrease in the red blood cell count and in hematocrit value caused by the esophagitis was significantly prevented by the treatment with PANa.

  1. Osmotic swelling of polyacrylate hydrogels in physiological salt solutions.

    PubMed

    Horkay, F; Tasaki, I; Basser, P J

    2000-01-01

    The swelling behavior of fully neutralized sodium polyacrylate gels was investigated in aqueous solutions of alkali metal (LiCl, NaCl, KCl, CsCl) and alkaline earth metal salts (CaCl2, SrCl2, BaCl2). The total salt concentration and the ratio of monovalent to divalent cations were varied in the biologically significant range. It is found that the concentrations of both monovalent and divalent cations vary continuously and smoothly in the gel despite the abrupt change in the gel volume. The individual elastic, mixing, and ionic contributions to the free energy of the gel were separately determined as a function of the degree of network swelling to elucidate the thermodynamics of swelling. Shear modulus measurements performed at different Ca2+ concentrations suggest that Ca2+ does not form stable cross-links between the polymer chains. At low and moderate swelling ratios the concentration dependence of the shear modulus follows a power law behavior, G variation of phi n, with n = 0.34 +/- 0.03. At high swelling degrees, however, the shear modulus increases with increasing swelling. The value of the Flory-Huggins interaction parameter, chi, determined from osmotic swelling pressure and shear modulus measurements, strongly depends on the ionic composition of the equilibrium solution and increases with increasing Ca2+ concentration.

  2. Effect of sodium polyacrylate on the hydrolysis of octacalcium phosphate.

    PubMed

    Bigi, A; Boanini, E; Falini, G; Panzavolta, S; Roveri, N

    2000-02-01

    Octacalcium phosphate (OCP) hydrolysis into hydroxyapatite (HA) has been investigated in aqueous solutions at different concentrations of sodium polyacrylate (NaPA). In the absence of the polyelectrolyte, OCP undergoes a complete transformation into HA in 48 h. The hydrolysis is inhibited by the polymer, which is significantly adsorbed on the crystals, up to about 22 wt.%. A polymer concentration of 10(-2) mM is sufficient to cause a partial inhibition of OCP to HA transformation, which is completely hindered at higher concentrations. The small platelet-like crystals in the TEM images of partially converted OCP can display electron diffraction patterns characteristic either of OCP single crystals or of polycrystalline HA, whereas the much bigger plate-like crystals exhibit diffraction patterns characteristic of OCP single crystals. The polyelectrolyte adsorption on OCP crystals is accompanied by an increase of their mean length and by a significant reduction of the coherence length of the perfect crystalline domains along the c-axis direction. It is suggested that the carboxylate-rich polyelectrolyte is adsorbed on the hydrated layer of the OCP (100) face, thus inhibiting its in situ hydrolysis into HA.

  3. Omniphobic low moisture permeation transparent polyacrylate/silica nanocomposite.

    PubMed

    Hsu, Sheng-Hao; Chang, Yuan-Ling; Tu, Yu-Chieh; Tsai, Chieh-Ming; Su, Wei-Fang

    2013-04-24

    We report the development of low moisture permeation and transparent dense polyacrylate/silica nanocomposite material that can exhibit both superhydrophobic and oleophobic (omniphobic) properties. The material was prepared by a three-step process. The first step involved the preparation of UV polymerizable solventless hybrid resin and the fabrication of nanocomposite. The hybrid resin consisted of a mixture of acrylate monomer, initiator, and acrylate-modified different size silica nanoparticles. The second step was to roughen the surface of the nanocomposite with unique nanotexture by oxygen plasma. In the third step, we applied a low surface tension fluoro monolayer on the treated surface. The nanocomposite exhibits desired superhydrophobicity and oleophobicity with a water contact angle of 158.2° and n-1-octadecene contact angle of 128.5°, respectively; low moisture permeation of 1.44 g·mm/m(2)·day; and good transparency (greater than 82% at 450-800 nm for ~60 μm film). The material has potential applications in optoelectronic encapsulation, self-cleaning coating, etc.

  4. Microencapsulation of pancreatic islets in a water insoluble polyacrylate.

    PubMed

    Sugamori, M E; Sefton, M V

    1989-01-01

    Rat pancreatic islets were encapsulated in a water insoluble polyacrylate (Eudragit RL), a model polymer, by coaxial extrusion and interfacial precipitation. Despite exposure to organic solvents and nonsolvents (diethyl phthalate, corn oil, and mineral oil) and to shear, the islets survived encapsulation. They continued to secrete insulin into the tissue culture medium and responded to glucose in both static glucose challenges and perifusion assays as well and as long as control islets which were not encapsulated, but were maintained in tissue culture alongside the encapsulated islets. Unfortunately, there was a great deal of variability in the performance of all islets studied, making unequivocal conclusions difficult. Some encapsulated islets survived more than 140 days in vitro and histologically appeared healthy. However, there appeared to be a general deterioration in insulin secretion capacity following prolonged culture in all islets, with corresponding changes (e.g., central necrosis) visible by microscopy. Although Eudragit RL is not practical as an encapsulation polymer, this study was useful in demonstrating that islets may be encapsulated in materials other than alginate-polylysine, and ultimately in materials that may have a more optimum blend of the desired properties: biocompatibility, permselectivity, and mechanical durability.

  5. The ABC transporter ABC40 encodes a phenylacetic acid export system in Penicillium chrysogenum.

    PubMed

    Weber, Stefan S; Kovalchuk, Andriy; Bovenberg, Roel A L; Driessen, Arnold J M

    2012-11-01

    The filamentous fungus Penicillium chrysogenum is used for the industrial production of β-lactam antibiotics. The pathway for β-lactam biosynthesis has been resolved and involves the enzyme phenylacetic acid CoA ligase that is responsible for the CoA activation of the side chain precursor phenylacetic acid (PAA) that is used for the biosynthesis of penicillin G. To identify ABC transporters related to β-lactam biosynthesis, we analyzed the expression of all 48 ABC transporters present in the genome of P. chryso-genum when grown in the presence and absence of PAA. ABC40 is significantly upregulated when cells are grown or exposed to high levels of PAA. Although deletion of this transporter did not affect β-lactam biosynthesis, it resulted in a significant increase in sensitivity to PAA and other weak acids. It is concluded that ABC40 is involved in weak acid detoxification in P. chrysogenum including resistance to phenylacetic acid.

  6. Fish-friendly prophylaxis/disinfection in aquaculture: Low concentration of peracetic acid is stress-free to the carp (Cyprinus carpio) after repeated applications

    USDA-ARS?s Scientific Manuscript database

    Application of peracetic acid (PAA) at low concentrations has been proved to be a broad functional and eco-friendly prophylaxis/disinfection method against various fish pathogens. Therefore, regular applications of low concentration PAA is sufficient to control (potential) pathogens in recirculatin...

  7. Alternative prophylaxis/disinfection in aquaculture - Adaptable stress induced by peracetic acid at low concentration and its application strategy in RAS

    USDA-ARS?s Scientific Manuscript database

    The application of peracetic acid (PAA) at low concentrations has been proven to be a broad-functioning and eco-friendly prophylaxis/disinfection method against various fish pathogens. However, there is lack of knowledge on how to apply PAA in a recirculating aquaculture system (RAS), and whether th...

  8. Kinetics of copper ion absorption by cross-linked calcium polyacrylate membranes

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.; May, C. E.

    1983-01-01

    The absorption of copper ions from aqueous copper acetate solutions by cross-linked calcium acrylate membranes was found to obey parabolic kinetics similar to that found for oxidation of metals that form protective oxide layers. For pure calcium polyacrylate membranes the rate constant was essentially independent of copper acetate concentration and film thickness. For a cross-linked copolymer film of polyvinyl alcohol and calcium polyacrylate, the rate constant was much greater and dependent on the concentration of copper acetate. The proposed mechanism in each case involves the formation of a copper polyacrylate phase on the surface of the membrane. The diffusion of the copper ion through this phase appears to be the rate controlling step for the copolymer film. The diffusion of the calcium ion is apparently the rate controlling step for the calcium polyacrylate. At low pH, the copper polyacrylate phase consists of the normal copper salt; at higher pH, the phase appears to be the basic copper salt.

  9. The inhibition of matrix metalloproteinase activity in chronic wounds by a polyacrylate superabsorber.

    PubMed

    Eming, Sabine; Smola, Hans; Hartmann, Berenike; Malchau, Gebhart; Wegner, Ronny; Krieg, Thomas; Smola-Hess, Sigrun

    2008-07-01

    Excessive matrix metalloproteinase (MMP) levels have been observed in wound fluid of impaired healing wounds. This is thought to interfere with granulation tissue formation as newly formed extracellular matrix and cytokines are degraded and the wound becomes deadlocked, unable to progress to the next healing stages. In the cleansing phase, associated with high MMP activity levels, hydroactive wound dressings containing polyacrylate superabsorber particles are particularly effective. We tested whether these particles can block MMP activity in wound fluid obtained from chronic venous leg ulcers. Polyacrylate superabsorber particles inhibited MMP activity by more than 87% in a fluorogenic peptide substrate assay. Further analysis revealed two underlying molecular mechanisms. First, experiments showed direct binding of MMPs to the particles. Secondly, polyacrylate superabsorber particles can bind Ca2+ and Zn2+ ions competing with MMPs for divalent ions required for enzymatic activity. Furthermore, we provide the first evidence in vivo that MMPs bind effectively to polyacrylate superabsorber particles within the hostile environment of chronic wounds. We conclude that polyacrylate superabsorber particles can rescue the highly proteolytic microenvironment of non-healing wounds from MMP activity so that more conductive conditions allow healing to proceed.

  10. Bioactivity and cytocompatibility of dicalcium phosphate/poly (amino acid) biocomposite with degradability

    NASA Astrophysics Data System (ADS)

    Zhang, Yunfei; Shan, Wenpeng; Li, Xiangde; Wei, Jie; Li, Hong; Ma, Jian; Yan, Yonggang

    2012-01-01

    A bioactive composite of dicalcium phosphate (DCP) and poly (amino acid) (PAA) was fabricated, and the in vitro bioactivity, degradability, and cellular responses to the DCP/PAA composite (DPC) were investigated as compared to PAA. Apatite formation on DPC surfaces occurred after immersion into simulated body fluid (SBF) for 7 days, but not on the surface of PAA. The weight loss ratio of DPC could reach 18.6 ± 0.3 wt% after soaking into phosphate buffered saline (PBS) for 2 months, which was higher than PAA (11.0 ± 0.2 wt%). Cell attachment and proliferation of MG-63 cells on DPC was obviously higher than on PAA. Moreover, the cells spread and formed confluent layer on the DPC surfaces. The alkaline phosphatase activity (ALP) of the cells on DPC was significantly greater than PAA at day 5 and day 7. The results suggested that introducing DCP into PAA makes the composite bioactive and more degradable, and meanwhile enhances osteoblast-like cells attach, proliferation and osteogenic differentiation.

  11. In-Use Evaluation of Peracetic Acid for High-Level Disinfection of Endoscopes.

    PubMed

    Chenjiao, Wu; Hongyan, Zhang; Qing, Gu; Xiaoqi, Zhong; Liying, Gu; Ying, Fang

    2016-01-01

    Many high-level disinfectants have been used for disinfection of endoscopes such as 2% glutaraldehyde (GA), 0.55% ortho-phthalaldehyde (OPA), and peracetic acid (PAA). Both GA and OPA are widely used in disinfection of endoscopes and have been previously discussed, but there is little research on the practical use of PAA as an endoscope disinfectant. An experimental model of a flexible gastrointestinal endoscope being contaminated with 9 strains of microorganism was designed. After the cleaning and disinfecting procedure was completed, we evaluated the biocidal activity (850 ppm PAA, 2% GA, and 0.55% OPA) on our flexible gastrointestinal endoscope model. We also evaluated sterilization effectiveness of PAA on other bacteria, including some antibiotic-resistant bacteria (methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and Clostridium difficile). The residual bacterial colony count number of the PAA-disinfected endoscope was significantly lower than that of the GA- and OPA-disinfected endoscopes. The biocidal effect and efficiency of the endoscope disinfection by PAA appeared to be better than either the GA- or OPA-disinfected endoscope. PAA has demonstrated a good sterilization effect on other bacterial species; of particular note are common antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and Clostridium difficile. The results of this study demonstrate that PAA is a fast and effective high-level disinfectant for use in the reprocessing of flexible endoscopes.

  12. Ionization of amphiphilic acidic block copolymers.

    PubMed

    Colombani, Olivier; Lejeune, Elise; Charbonneau, Céline; Chassenieux, Christophe; Nicolai, Taco

    2012-06-28

    The ionization behavior of an amphiphilic diblock copolymer poly(n-butyl acrylate(50%)-stat-acrylic acid(50%))(100)-block-poly(acrylic acid)(100) (P(nBA(50%)-stat-AA(50%))(100)-b-PAA(100), DH50) and of its equivalent triblock copolymer P(nBA(50%)-stat-AA(50%))(100)-b-PAA(200)-b-P(nBA(50%)-stat-AA(50%))(100) (TH50) were studied by potentiometric titration either in pure water or in 0.5 M NaCl. These polymers consist of a hydrophilic acidic block (PAA) connected to a hydrophobic block, P(nBA(50%)-stat-AA(50%))(100), whose hydrophobic character has been mitigated by copolymerization with hydrophilic units. We show that all AA units, even those in the hydrophobic block could be ionized. However, the AA units within the hydrophobic block were less acidic than those in the hydrophilic block, resulting in the preferential ionization of the latter block. The preferential ionization of PAA over that of P(nBA(50%)-stat-AA(50%))(100) was stronger at higher ionic strength. Remarkably, the covalent bonds between the PAA and P(nBA(50%)-stat-AA(50%))(100) blocks in the diblock or the triblock did not affect the ionization of each block, although the self-association of the block copolymers into spherical aggregates modified the environment of the PAA blocks compared to when PAA was molecularly dispersed.

  13. Study of bone-like hydroxyapatite/polyamino acid composite materials for their biological properties and effects on the reconstruction of long bone defects.

    PubMed

    Yan, Ling; Jiang, Dian-ming

    2015-01-01

    The purpose of this study was to investigate the effect of bone-like hydroxyapatite/polyamino acid (BHA/PAA) in the osteogenesis and reconstruction of long segmental bone defects. In vitro, MG63 cells were cultured with BHA/PAA. The osteoinductive activity of the BHA/PAA material was evaluated using inverted microscopy, scanning electron microscopy, MTT proliferation assay, and the determination of alkaline phosphatase activity and Ca(2+) content. In vivo, the radial bone defect was made in 20 New Zealand White rabbits, and then these animal were randomly divided into two groups (n=10), the experimental group (with BHA/PAA) and the control group (without BHA/PAA). Postoperatively, the osteogenesis effect of BHA/PAA was evaluated through X-ray, hematoxylin-eosin staining, observation of the gross bone specimen, immunohistochemistry, and fluorescent confocal scanning microscopy. In vitro, BHA/PAA promoted the adhesion, growth, and calcium nodule formation of MG63 cells, and it had good osteogenesis activity. In vivo, with BHA/PAA material degradation and absorption, the new bone gradually formed, and the bone defect gradually recovered in the experimental group. In the control group, a limited bone formation was found at the bone broken ends, and the bone defect was obviously visible. In vitro and in vivo, we confirmed that BHA/PAA was effective in inducing osteogenesis and reconstructing a long segmental bone defect.

  14. The effect of TiO2/aluminosilicate nanocomposite additives on the mechanical and thermal properties of polyacrylic coatings

    NASA Astrophysics Data System (ADS)

    Nosrati, Rahimeh; Olad, Ali

    2015-12-01

    The commercial grade polyacrylic latex was modified in order to prepare a mechanical and thermal improved coating. TiO2/Ag-exchanged-aluminosilicate nanocomposites with montmorillonite, zeolite-A and clinoptilolite aluminosilicates were prepared and used as additive in the matrix of polyacrylic latex to achieve a coating with proper mechanical and thermal properties. X-ray diffraction patterns and FESEM were used to characterize the composition, structure, and morphology of the nanocomposite additives. Polyacrylic coatings modified by TiO2/Ag-exchanged-aluminosilicate nanocomposite additives showed higher adhesion strength and hardness compared to unmodified commercial grade polyacrylic coatings. Differential Scanning Calorimetry (DSC) analysis showed lower glass transition temperature for modified polyacrylic coatings than that of unmodified polyacrylic coatings. The tensile tests were also carried out for unmodified and modified polyacrylic coatings. According to the results, the modified polyacrylic based coating with TiO2/Ag-exchanged-clinoptilolite nanocomposite additive was the best coating considering most of useful properties.

  15. Nanosilica and Polyacrylate/Nanosilica: A Comparative Study of Acute Toxicity

    PubMed Central

    Niu, Ying-Mei; Zhu, Xiao-Li; Chang, Bing; Tong, Zhao-Hui; Cao, Wen; Qiao, Pei-Huan; Zhang, Lin-Yuan; Zhao, Jing; Song, Yu-Guo

    2016-01-01

    We compared the acute toxicity of nanosilica and polyacrylate/nanosilica instillation in Wistar rats (n = 60). Exposure to nanosilica and polyacrylate/nanosilica showed a 30% mortality rate. When compared with saline-treated rats, animals in both exposure groups exhibited a significant reduction of PO2 (P < 0.05) at both 24 and 72 hr. after exposure. Both exposure groups exhibited a significant reduction of neutrophils in arterial blood compared to saline controls (P < 0.05) 24 hr. after exposure. The levels of blood ALT and LDH in exposed groups were found to be significantly increased (P < 0.05) 24 hr. following exposure. The exposed groups exhibited various degrees of pleural effusion and pericardial effusion. Our findings indicated respiratory exposure to polyacrylate/nanosilica and nanosilica is likely to cause multiple organ toxicity. PMID:26981538

  16. Nanosilica and Polyacrylate/Nanosilica: A Comparative Study of Acute Toxicity.

    PubMed

    Niu, Ying-Mei; Zhu, Xiao-Li; Chang, Bing; Tong, Zhao-Hui; Cao, Wen; Qiao, Pei-Huan; Zhang, Lin-Yuan; Zhao, Jing; Song, Yu-Guo

    2016-01-01

    We compared the acute toxicity of nanosilica and polyacrylate/nanosilica instillation in Wistar rats (n = 60). Exposure to nanosilica and polyacrylate/nanosilica showed a 30% mortality rate. When compared with saline-treated rats, animals in both exposure groups exhibited a significant reduction of PO2 (P < 0.05) at both 24 and 72 hr. after exposure. Both exposure groups exhibited a significant reduction of neutrophils in arterial blood compared to saline controls (P < 0.05) 24 hr. after exposure. The levels of blood ALT and LDH in exposed groups were found to be significantly increased (P < 0.05) 24 hr. following exposure. The exposed groups exhibited various degrees of pleural effusion and pericardial effusion. Our findings indicated respiratory exposure to polyacrylate/nanosilica and nanosilica is likely to cause multiple organ toxicity.

  17. Attenuating the size and molecular carrier capabilities of polyacrylate nanoparticles by a hydrophobic fluorine effect.

    PubMed

    Labruère, Raphaël; Turos, Edward

    2012-08-15

    This study investigates the effect of introducing alkyl chain fluorination on the properties of polyacrylate nanoparticles prepared in aqueous solution by emulsion polymerization. For this, 2,2,3,3,4,4,4-heptafluorobutyl acrylate (1) and methyl trifluoroacrylate (2) were tested as monomers as a means to prepare fluorinated polyacrylate nanoparticles to evaluate how side chain fluorination may affect nanoparticle size and drug carrier properties. Our results show that as fluorine content within the polyacrylate matrix increases, the size of the nanoparticle systematically diminishes, from 45 nm (for nanoparticles containing no fluoroacrylate) to ~7 nm (for nanoparticles constructed solely of fluoroacrylate). We also observe that as fluoroacrylate content and hydrophobicity increases, the nanoparticles decrease their ability to incorporate lipophilic molecules during the process of emulsification. These findings have meaningful implications in the implementation of fluorinated nanoparticles in molecular delivery.

  18. Use of oral sodium polyacrylate in rat gastrointestinal alkali burns.

    PubMed

    Ehrenpreis, E D; Leikin, J B; Ehrenpreis, S; Goldstein, J L

    1988-04-01

    Alkali-induced injuries of the esophagus and stomach are currently medically managed with steroids and antibiotics. We investigated whether treatment with sodium polyacrylate (PANa), a proposed mucosal protectant, could decrease the deleterious effect of alkali injuries or prevent alkali injuries. Rats were randomized in 4 groups. Group I (control; n = 7) received 0.1 ml normal saline via gastric gavage. Groups II-IV received 0.1 ml 25% NaOH. Group II (n = 22) received no further treatment. Group III (n = 9) received 0.25% PANa ad lib in drinking water for 3 days prior to NaOH. Group IV received 0.25% PANa for 6 days after NaOH. Animals were weighed daily. At 6 days post NaOH, stomachs were removed from animals in Groups II-IV and burn lesions were outlined on tracing paper. 1 x 1 cm sections of burned areas were fixed, stained with H&E and histologically evaluated. In another study, 0.1 ml of 10% NaOH was given to 2 groups of animals. Group I (n = 22) received no other treatment, while Group II (n = 13) received PANa ad lib in drinking water for 3 days prior to NaOH. Of the animals treated with 25% NaOH, only those in Group II showed a decrease mean weight which was statistically significant on Day 4, p = 0.016. Mean burn areas were statistically greater in Group II than in Group IV (p = 0.025), while histologically, lesions were similar. Pretreatment with PANa prior to 10% NaOH prevented the weight loss which occurred daily in the control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Dual-setting calcium phosphate cement modified with ammonium polyacrylate.

    PubMed

    dos Santos, Luís Alberto; Carrodeguas, Raúl García; Boschi, Anselmo Ortega; de Arruda, Antônio Celso

    2003-05-01

    alpha-Tricalcium phosphate bone cement, as formerly designed and developed by Driessens et al., consists of a powder composed by alpha-tricalcium phosphate (alpha-TCP) and hydroxyapatite (HA) seeds, and an aqueous solution of Na2HPO4 as mixing liquid. After mixing powder and liquid, alpha-TCP dissolves into the liquid and calcium deficient hydroxyapatite (CDHA), more insoluble than the former, precipitates as an entanglement of crystals, which causes the setting and hardening of the cement. alpha-TCP bone cement offers several advantages in comparison to calcium phosphate bioceramics and acrylic bone cements as bone graft and repairing material, like perfect adaptability to the defect size and shape, osteotransductibility, and absence of thermal effect during setting. The main handicap is its low mechanical strength. Therefore, approaching its mechanical strength to that of human bone could considerably extend its applications. In the present work, an in situ polymerization system based on acrylamide (AA) and ammonium polyacrylate (PA) as liquid reducer was added to alpha-TCP cement to increase its mechanical strength. The results showed that the addition of 20 wt% of acrylamide and 1 wt% AP to the liquid increased the compressive and tensile strength of alpha-TCP bone cement by 149 and 69% (55 and 21 MPa), respectively. The improvement in mechanical strength seems to be caused by a decrease of porosity and the reinforcing effect of a polyacrylamide network coexisting with the entanglement of CDHA crystals. The studied additives do not affect the nature of the final product of the setting reaction, CDHA, but promote the reduction of its crystal size.

  20. Evaluation of Combined Peracetic acid and UV treatment for ...

    EPA Pesticide Factsheets

    The current study evaluates the effectiveness of the combined application of Peracetic acid and ultraviolet radiation as alternative disinfectant agents to the traditional chlorination of wastewater effluents. Various pathogens (E. coli, enterococci and fecal coliforms) were evaluated in the study. Four experiments were conducted using low to high PAA levels and UV dosages. E. coli and enterococci were resistant to low to moderate PAA dosage (0.5- 1 mg/L). These microbes can be removed effectively at high PAA dosage (2.5 mg/L) with 30 min contact time. Fecal coliforms were completely inactivated even at a low PAA dose of 0.7 mg/L. E. coli was more susceptible to UV disinfection than enterococci at low UV dosages. Enterococci required at least 40 mJ/cm2 for 2.5 log inactivation. In combined PAA + UV treatment, low UV intensities between 7 – 40 mJ/cm2 showed poor disinfection performance at a low PAA concentration of 1.5 mg/L. High UV intensities of 120 and 60 mJ/cm2 inactivated all the pathogens to below detection levels even at low to moderate PAA (0.7 mg/L and 1 mg/L) pretreatment concentration. Combined PAA + UV treatment at 1 mg/L (for 15 and 30 min contact time) + 120 and 60 mJ/cm2 did not show any regrowth of microbes, whereas PAA only disinfection with 15 min contact time showed regrowth of enterococci and fecal coliforms. UV only disinfection showed E. coli regrowth. • This pilot scale study was designed for providing necessary parameter optimization

  1. Peroxyacetic acid in urban and rural atmosphere: concentration, feedback on PAN-NOx cycle and implication on radical chemistry

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Chen, Z. M.; He, S. Z.; Hua, W.; Zhao, Y.; Li, J. L.

    2010-01-01

    Peroxyacetic acid (PAA) is one of the most important atmospheric organic peroxides, which have received increasing attention for their potential contribution to the oxidation capacity of the troposphere and the formation of secondary aerosols. We report here, for the first time, a series of data for atmospheric PAA concentrations at urban and rural sites, from five field campaigns carried out in China in summer 2006, 2007 and 2008. For these five measurements, daytime mean (08:00-20:00 LT) PAA concentrations on sunlit days were 21.4-148.0 pptv with a maximum level of ~1 ppbv. The various meteorological and chemical parameters influencing PAA concentrations were examined using Principal Factor Analysis. This statistical analysis shows that the local photochemical production was the major source of PAA, and its concentration increased with increasing temperature, solar radiation and ozone but decreased with increasing NOx (NO and NO2), CO, SO2, and relative humidity. Based on the dataset, several issues are highlighted in this study: (i) Because PAA is a product from the photochemical oxidation of some specific volatile organic compounds (VOCs) that lead to acetyl peroxy radicals, the importance of various VOCs with respect to the PAA formation is therefore ranked using the incremental reactivity method. (ii) The contribution of PAN thermal degradation to PAA formation under conditions of different NOx concentrations is estimated based on the chemical kinetics analysis. The result shows that PAN seems to play an important role in the formation of PAA when the NO/NO2 concentration ratio was less than 0.2 and PAA would correspondingly have feedback on the PAN-NOx cycle. (iii) PAA and other peroxides, such as methyl hydroperoxide (MHP) and H2O2, usually exhibited a similar asymmetric shape typically shifted to the afternoon. However, under some conditions, H2O2 diurnal cycle was out of phase with MHP and PAA. The combination of linear regression and kinetics analysis

  2. One-step synthesis of Poly(amic acid)/ZnO composite particles and its SERS applications

    NASA Astrophysics Data System (ADS)

    Wu, Jun Yi; Hsu, Keh-Ying

    2015-11-01

    Raspberry like structured PAA/ZnO microsphere were realized by coating the ZnO nanoparticles onto the surface of PAA microsphere via a novel solution method. The obtained materials were characterized by means of X-ray diffraction (XRD), scanning electron microscopy(SEM),transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) absorption measurement. It was shown that ZnO nanoparticles were successfully grown on the surface of PAA microsphere. The absorption band of PAA/ZnO raspberry microsphere showed a large redshift comparing to pure ZnO nanoparticles, indicating the strong interfacial interaction between PAA and ZnO. This approach was simple, mild and readily scaled up, affording a simple method for the synthesis of raspberry like structure. The resulting Poly(amic acid)/ZnO composite structures could be used as a substrate for surface enhanced Raman scattering(SERS).

  3. Peracetic acid is effective for controlling fungus on channel catfish eggs.

    PubMed

    Straus, D L; Meinelt, T; Farmer, B D; Mitchell, A J

    2012-07-01

    Peracetic acid (PAA) is a relatively new compound suggested for use to treat pathogens in aquaculture. It is approved for use in Europe, but not in the United States. This study determined the effectiveness of PAA for fungus control on channel catfish, Ictalurus punctatus (Rafinesque), eggs. The study consisted of five PAA concentrations (2.5, 5, 10, 15 and 20mgL(-1) ) and an untreated control in a flow-through system. A single spawn was used for each replication (N =4). Eggs were treated twice daily until the embryos developed eyes. When hatching was complete for all viable eggs, fry were counted to determine the percent survival in each treatment. Fungal growth was severe in the untreated controls resulting in 11% survival. Treatments of 2.5, 5 and 10mgL(-1) PAA were significantly different from the controls (P<0.05). The highest percent survival of hatched fry was with 5mgL(-1) PAA administered twice daily; the 2.5mgL(-1) PAA treatment had slightly less survival, but gives a higher margin of safety in case of treatment error. Very little fungus was present in treatments receiving 2.5mgL(-1) PAA or higher, and concentrations of 15 and 20mgL(-1) PAA were toxic to the eggs. The mean survivals in the 0, 2.5, 5, 10, 15 and 20mgL(-1) PAA treatments were 11%, 60%, 63%, 62%, 32% and 0%, respectively. Therefore, PAA may be a compound that merits further investigations regarding its use in U.S. aquaculture.

  4. Defence strategies and antibiotic resistance gene abundance in enterococci under stress by exposure to low doses of peracetic acid.

    PubMed

    Turolla, Andrea; Sabatino, Raffaella; Fontaneto, Diego; Eckert, Ester M; Colinas, Noemi; Corno, Gianluca; Citterio, Barbara; Biavasco, Francesca; Antonelli, Manuela; Mauro, Alessandro; Mangiaterra, Gianmarco; Di Cesare, Andrea

    2017-10-01

    Peracetic acid (PAA) is an organic compound used efficiently as disinfectant in wastewater treatments. Yet, at low doses it may cause selection; thus, the effect of low doses of PAA on Enterococcus faecium as a proxy of human-related microbial waste was evaluated. Bacteria were treated with increasing doses of PAA (from 0 to 25 mg L(-1) min) and incubated in regrowth experiments under non-growing, limiting conditions and under growing, favorable conditions. The changes in bacterial abundance, in bacterial phenotype (number and composition of small cell clusters), and in the abundance of an antibiotic resistance gene (ARG) was evaluated. The experiment demonstrated that the selected doses of PAA efficiently removed enterococci, and induced a long-lasting effect after PAA inactivation. The relative abundance of small clusters increased during the experiment when compared with that of the inoculum. Moreover, under growing favorable conditions the relative abundance of small clusters decreased and the number of cells per cluster increased with increasing PAA doses. A strong stability of the measured ARG was found, not showing any effect during the whole experiment. The results demonstrated the feasibility of low doses of PAA to inactivate bacteria. However, the stress induced by PAA disinfection promoted a bacterial adaptation, even if potentially without affecting the abundance of the ARG. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Test methods for estimating the efficacy of the fast-acting disinfectant peracetic acid on surfaces of personal protective equipment.

    PubMed

    Lemmer, Karin; Howaldt, Sabine; Heinrich, Renate; Roder, Anja; Pauli, Georg; Dorner, Brigitte G; Pauly, Diana; Mielke, Martin; Schwebke, Ingeborg; Grunow, Roland

    2017-08-29

    The work aimed at developing and evaluating practically relevant methods for testing of disinfectants on contaminated personal protective equipment (PPE). Carriers were prepared from PPE fabrics and contaminated with B. subtilis spores. Peracetic acid (PAA) was applied as suitable disinfectant. In method 1 the contaminated carrier was submerged in PAA solution, in method 2 the contaminated area was covered with PAA and in method 3 PAA, preferentially combined with a surfactant, was dispersed as a thin layer. In each method, 0.5% to 1% PAA reduced the viability of spores by a factor of ≥6 log10 within 3 min. The technique of the most realistic method 3 proved to be effective at low temperatures and also with a high organic load. Vaccinia- and Adenovirus were inactivated with 0.05% to 0.1% PAA by up to ≥6 log10 within 1 min. The cytotoxicity of ricin was considerably reduced by 2% PAA within 15 min of exposure. PAA/detergent mixture enabled to cover hydrophobic PPE surfaces with a thin and yet effective disinfectant layer. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  6. Effect of peracetic acid and aldehyde disinfectants on biofilm.

    PubMed

    Henoun Loukili, N; Becker, H; Harno, J; Bientz, M; Meunier, O

    2004-10-01

    The effects of two aldehyde (Cidex, Endosporine) and four peracetic acid (PAA) (Nu Cidex, Anioxyde 1000, Hydraseptic, Peralkan) disinfectants on an Escherichia coli biofilm model were studied. The biofilm was prepared in glass tubes, and evaluated indirectly using a colourimetric method. The ability of the disinfectants to fix or remove the biofilm from tubes was determined by their detergent activity (DA). The two aldehyde derivatives and two of the PAA (Nu Cidex, Anioxyde 1000) agents fixed the biofilm. However, the effects of Hydraseptic and Peralkan were equivalent to the control (sterile water). Regardless of their disinfectant activity, PAA agents display different DAs that could be used to select the weakest biofilm-fixing agents. Users should be concerned about the efficiency of the cleaning stage of medical devices, and when choosing a PAA product, non-fixing ability should be considered in addition to antimicrobial activity.

  7. Dual peptide nucleic acid- and peptide-functionalized shell cross-linked nanoparticles designed to target mRNA toward the diagnosis and treatment of acute lung injury.

    PubMed

    Shrestha, Ritu; Shen, Yuefei; Pollack, Kevin A; Taylor, John-Stephen A; Wooley, Karen L

    2012-03-21

    In this work, multifunctional biosynthetic hybrid nanostructures were prepared and studied for their potential utility in the recognition and inhibition of mRNA sequences for inducible nitric oxide synthase (iNOS), which are overexpressed at sites of inflammation, such as in cases of acute lung injury. Shell cross-linked knedel-like polymer nanoparticles (SCKs) that present peptide nucleic acids, for binding to complementary mRNAs, and cell penetrating peptides (CPPs), to gain cell entry, along with fluorescent labels and sites for radiolabeling, were prepared by a series of robust, efficient, and versatile synthetic steps that proceeded from monomers to polymers to functional nanoparticles. Amphiphilic block graft copolymers having combinations of methoxy- and thioacetyl-terminated poly(ethylene glycol) (PEG) and DOTA-lysine units grafted from the backbone of poly(acrylic acid) (PAA) and extending with a backbone segment of poly(octadecyl acrylate-co-decyl acrylate) (P(ODA-co-DA)) were prepared by a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and chemical modification reactions, which were then used as the building blocks for the formation of well-defined SCKs decorated with reactive thiols accessible to the surface. Fluorescent labeling with Alexa Fluor 633 hydrazide was then accomplished by amidation with residual acrylic acid residues within the SCK shells. Finally, the PNAs and CPP units were covalently conjugated to the SCKs via Michael addition of thiols on the SCKs to maleimide units on the termini of PNAs and CPPs. Confirmation of the ability of the PNAs to bind selectively to the target iNOS mRNAs when tethered to the SCK nanoparticles was determined by in vitro competition experiments. When attached to the SCKs having a hydrodynamic diameter of 60 ± 16 nm, the K(d) values of the PNAs were ca. an order of magnitude greater than the free PNAs, while the mismatched PNA showed no significant binding.

  8. Acute toxicity of peracetic acid to fish

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA; also called peroxyacetic acid) is a promising new therapeutant for parasites and fungus. It is registered with the U.S. Environmental Protection Agency (EPA) as an antimicrobial compound approved for indoor use on hard, non-porous surfaces. This study determined the acute toxi...

  9. Molecular Understanding and Structural-Based Design of Polyacrylamides and Polyacrylates as Antifouling Materials.

    PubMed

    Chen, Hong; Zhao, Chao; Zhang, Mingzhen; Chen, Qiang; Ma, Jie; Zheng, Jie

    2016-04-12

    Design and synthesis of highly bioinert and biocompatible antifouling materials are crucial for a broad range of biomedical and engineering applications. Among antifouling materials, polyacrylamides and polyacrylates have proved so promising because of cheap raw materials, ease of synthesis and applicability, and abundant functional groups. The strong surface hydration and the high surface packing density of polyacrylamides and polyacrylates are considered to be the key contributors to their antifouling property. In this article, we review our studies on the design and synthesis of a series of polyacrylamides and polyacrylates with different molecular structures. These polymers can be fabricated into different architectural forms (brushes, nanoparticles, nanogels, and hydrogels), all of which are highly resistant to the attachment of proteins, cells, and bacteria. We find that small structural changes in the polymers can lead to large enhancement in surface hydration and antifouling performance, both showing a positive correlation. This reveals a general design rule for effective antifouling materials. Furthermore, polyacrylamides and polyacrylates are readily functionalized with other bioactive compounds to achieve different new multifunctionalities.

  10. Influence of sodium polyacrylate on the rheology of aqueous Laponite dispersions.

    PubMed

    Labanda, Jordi; Llorens, Joan

    2005-09-01

    Aqueous Laponite dispersions containing a sodium polyacrylate were analyzed, at fixed ionic strength and pH, by rheometric and electroacoustic (for zeta-potential determinations) techniques at 7 days after their preparation. The rheological behavior of these dispersions was determined by oscillatory and flow experiments. Addition of sodium polyacrylate modifies the interactions between Laponite particles and therefore the physical state of the dispersion. The phase diagram of Laponite dispersion as a function of sodium polyacrylate concentration shows different sol-gel transitions for a specific Laponite concentration as a function of the polyacrylate concentration. Under equilibrium flow conditions the Laponite dispersions fit the pseudoplastic Oswald-de Waele power law model. At the same time, these dispersions show thixotropy, which was analyzed using a second-order kinetic equation. The kinetic processes were characterized by breakdown and build-up parameters, which were found to depend on shear rate. This kinetic equation was modified by a power law exponent of viscosity with shear rate that takes into account the viscosity variations when the shear rates are suddenly changed, in order to fit the hysteresis loops.

  11. Fluorescence properties of a novel side-chain polymer based on polyamic acid

    NASA Astrophysics Data System (ADS)

    Lu, Jianmei; Yao, Shechun; Tang, Xiubo; Sun, Ming; Zhu, Xiulin

    2004-05-01

    The p-π conjugated polyamic acid (PAA) had been synthesized through 1,4-diaminoanthraquinone (DAAQ) and pyromellitic dianhydride (PMDA) under microwave irradiation. The graft PAAs were obtained by toluene-2,4-diisocyanate (TDI) derivatives having different straight-chain alkyl. The resulted graft polymers had good dissolution capabilities, film-forming capabilities and strong fluorescence. We investigated some factors influencing fluorescence performance on graft PAA and found that with increasing chain length of the straight-chain alkyl or increasing graft degree, the fluorescence intensity and quantum efficiency will be enhanced markedly.

  12. Growth arrest of lung carcinoma cells (A549) by polyacrylate-anchored peroxovanadate by activating Rac1-NADPH oxidase signalling axis.

    PubMed

    Chatterjee, Nirupama; Anwar, Tarique; Islam, Nashreen S; Ramasarma, T; Ramakrishna, Gayatri

    2016-09-01

    Hydrogen peroxide is often required in sublethal, millimolar concentrations to show its oxidant effects on cells in culture as it is easily destroyed by cellular catalase. Previously, we had shown that diperoxovanadate, a physiologically stable peroxovanadium compound, can substitute H2O2 effectively in peroxidation reactions. We report here that peroxovanadate when anchored to polyacrylic acid (PAPV) becomes a highly potent inhibitor of growth of lung carcinoma cells (A549). The early events associated with PAPV treatment included cytoskeletal modifications, increase in GTPase activity of Rac1, accumulation of the reactive oxygen species, and also increase in phosphorylation of H2AX (γH2AX), a marker of DNA damage. These effects persisted even at 24 h after removal of the compound and culminated in increased levels of p53 and p21 together with growth arrest. The PAPV-mediated growth arrest was significantly abrogated in cells pre-treated with the N-acetylcysteine, Rac1 knocked down by siRNA and DPI an inhibitor of NADPH oxidase. In conclusion, our results show that polyacrylate derivative of peroxovanadate efficiently arrests growth of A549 cancerous cells by activating the axis of Rac1-NADPH oxidase leading to oxidative stress and DNA damage.

  13. Fabrication and characterization of stable superhydrophobic fluorinated-polyacrylate/silica hybrid coating

    NASA Astrophysics Data System (ADS)

    Li, Kunquan; Zeng, Xingrong; Li, Hongqiang; Lai, Xuejun

    2014-04-01

    The core-shell fluorinated-polyacrylate (PFA) emulsion was synthesized through emulsion polymerization method and the superhydrophobic PFA/SiO2 hybrid coating was successfully fabricated on the slide glass by spraying the mixture of PFA emulsion and hydrophobic SiO2 particles using ethanol as cosolvent. The PFA emulsion was characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), water contact angle (WCA), transmission electron microscopy (TEM), and the effects of SiO2 content on the wetting behavior and surface morphology of PFA/SiO2 hybrid coating were investigated. To evaluate the stability of the hybrid coating, the acid and base resistance, weatherability and thermal stability were also studied. Results showed that the obtained PFA latex exhibited a core-shell structure with a particle size of 134.1 nm and a narrow polydispersity of 0.03. With the increase of dodecafluoroheptyl methacrylate (DFMA) content in the latex shell from 0 wt% to 31.8 wt%, the WCA of the PFA film enlarged from 85° to 104°, indicating that the introduction of fluorinated monomer was effective in reducing the surface energy. By adding different amount of SiO2 particles, the surface morphology and wetting behavior of the PFA/SiO2 hybrid coatings could be controlled. When the mass ratio of SiO2 to PFA emulsion was 0.2, the surface roughness (Rq) increased to 173.6 nm and the wetting behavior of the surface became superhydrophobic with a WCA of 153°, resulted from the corporation of low surface energy and the binary nano/microstructure on the surface. The as-prepared PFA/SiO2 hybrid coating showed good acid and base corrosion resistance, and it could keep superhydrophobicity after being heated at 250 °C for 2 h or exposed to ambient atmosphere for more than 3 months. Additionally, the superhydrophobic PFA/SiO2 hybrid coating could be applied to various substrates through spraying. This was a green and eco-friendly method in fabricating stable

  14. Acute toxicity of peracetic acid to various fish species

    USDA-ARS?s Scientific Manuscript database

    Peracetic acid (PAA; also called peroxyacetic acid) is a promising disinfectant in the US aquaculture industry to control parasites and fungus. It is a stabilized mixture of acetic acid and hydrogen peroxide that does not leave dangerous residues in the environment when it breaks down as most compo...

  15. Peroxyacetic acid in urban and rural atmosphere: concentration, feedback on PAN-NOx cycle and implication on radical chemistry

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Chen, Z. M.; He, S. Z.; Hua, W.; Zhao, Y.; Li, J. L.

    2009-10-01

    Peroxyacetic Acid (PAA) is one of important atmospheric organic peroxides, which have received increasing attention for their potential contribution to the oxidation capacity of the troposphere and the formation of secondary aerosols. We report here that, for the first time, a series of data for atmospheric PAA concentrations at urban and rural sites, from five field campaigns carried out in China in summer 2006, 2007 and 2008. For these five measurements, daytime mean PAA concentrations on sunlit days were 0.02-0.14 ppbv with a maximum level of ~1 ppbv. The various meteorological and chemical parameters influencing PAA concentrations were examined using the Principal Factor Analysis. This statistical analysis shows that the local photochemical production was the major source of PAA, and its concentration increased with increasing temperature, solar radiation and ozone but decreased with increasing NOx (NO and NO2), CO, SO2, and relative humidity. Based on the dataset, several issues are highlighted in this study: (i) because PAA is a product from the photochemical oxidation of some specific volatile organic compounds (VOCs) that lead to acetyl peroxy radicals, the importance of various VOCs with respect to the PAA formation is therefore ranked using the incremental reactivity method. (ii) The contribution of PAN thermal degradation to PAA formation under conditions of different NOx concentrations is estimated based on the chemical kinetics analysis. The result shows that PAN seems to play an important role in the formation of PAA when the NO/NO2 concentration ratio was less than 0.2 and PAA would correspondingly have feedback on the PAN-NOx cycle. (iii) PAA and other peroxides, such as methyl hydroperoxide (MHP) and H2O2, usually exhibited a similar asymmetric shape typically shifted to the afternoon. However, at a high SO2 level, H2O2 showed a profile different from those of MHP and PAA. The combination of linear regression and chemical kinetics analysis reveals

  16. Ear-like poly (acrylic acid)-activated carbon nanocomposite: A highly efficient adsorbent for removal of Cd(II) from aqueous solutions.

    PubMed

    Ge, Huacai; Wang, Jincui

    2017-02-01

    Poly (acrylic acid) modified activated carbon nanocomposite (PAA-AC) was synthesized. The structure and morphology of this nanocomposite were characterized by FTIR, SEM, TEM, XRD and Zeta potential. The adsorption of some heavy metal ions on PAA-AC was studied. The characterization results indicated that PAA-AC was a novel and ear-like nanosheet material with the thickness of about 40 nm and the diameter of about 300 nm. The adsorption results exhibited that the introduction of carboxyl groups into activated carbon evidently increased the uptake for heavy metal ions and the nanocomposite had maximum uptake for Cd(II). Various variables affecting adsorption of PAA-AC for Cd(II) were systematically explored. The maximum capacity and equilibrium time for adsorption of Cd(II) by PAA-AC were 473.2 mg g(-1) and 15 min. Moreover, the removal of Cd(II) for real electroplating wastewater by PAA-AC could reach 98.5%. These meant that the removal of Cd(II) by PAA-AC was highly efficient and fast. The sorption kinetics and isotherm fitted well with the pseudo-second-order model and Langmuir model, respectively. The adsorption mainly was a chemical process by chelation. Thermodynamic studies revealed that the adsorption was a spontaneous and endothermic process. The results revealed that PAA-AC could be considered as a potential candidate for Cd(II) removal.

  17. STXM/C 1s-NEXAFS study of Eu(III) and Uranyl humic acid aggregates at different pH

    NASA Astrophysics Data System (ADS)

    Plaschke, M.; Rothe, J.; Denecke, M. A.; Geckeis, H.

    2010-04-01

    Humic acids (HA) are chemically heterogeneous and structurally ill-defined biopolymers which are able to bind traces of actinides or lanthanides. Due to their dimensions in the colloidal size range they may affect transport of these elements in aquatic systems. Eu(III)- and UO22+-HA aggregates have been investigated by Scanning Transmission X-ray Microscopy (STXM) and C 1s-NEXAFS under systematic variation of pH. In the Eu(III)- and UO22+-HA systems aggregate morphologies at near neutral pH were similar to those observed in previous studies: optically dense zones (high absorption at the carbon K-edge) are embedded in a matrix of less dense material. C 1s-NEXAFS signatures observed in the different zones, i.e., the intensity of the characteristic complexation feature previously experimentally described and recently theoretically characterized, strongly depends on sample pH. In the alkaline regime (pH 9) with added carbonate, co-precipitation of Eu(III)-carbonate (or ternary carbonate/(oxo)hydroxide complexes) with the Eu(III)-HA majority fraction is observed but Eu(III) binding to HA over carbonate in the dense zones seems to be favoured. The UO22+-HA system exhibits in alkaline solution more compact morphologies combined with a strong metal ion complexation effect in the NEXAFS. Eu(III) and UO22+ polyacrylic acid (PAA) aggregates used as HA model systems show similar spectral trends; these aggregates exhibit highly branched morphologies without segregation into zones with different NEXAFS signatures. The chemical environment such as pH or the type of metal cation strongly influences both HA aggregate morphologies and NEXAFS spectral signatures. These can, in turn, be used as indicators of the strength of lanthanide or actinide ion bound HA interaction.

  18. A simple method for decomposition of peracetic acid in a microalgal cultivation system.

    PubMed

    Sung, Min-Gyu; Lee, Hansol; Nam, Kibok; Rexroth, Sascha; Rögner, Matthias; Kwon, Jong-Hee; Yang, Ji-Won

    2015-03-01

    A cost-efficient process devoid of several washing steps was developed, which is related to direct cultivation following the decomposition of the sterilizer. Peracetic acid (PAA) is known to be an efficient antimicrobial agent due to its high oxidizing potential. Sterilization by 2 mM PAA demands at least 1 h incubation time for an effective disinfection. Direct degradation of PAA was demonstrated by utilizing components in conventional algal medium. Consequently, ferric ion and pH buffer (HEPES) showed a synergetic effect for the decomposition of PAA within 6 h. On the contrary, NaNO3, one of the main components in algal media, inhibits the decomposition of PAA. The improved growth of Chlorella vulgaris and Synechocystis PCC6803 was observed in the prepared BG11 by decomposition of PAA. This process involving sterilization and decomposition of PAA should help cost-efficient management of photobioreactors in a large scale for the production of value-added products and biofuels from microalgal biomass.

  19. Peracetic acid for secondary effluent disinfection: a comprehensive performance assessment.

    PubMed

    Antonelli, M; Turolla, A; Mezzanotte, V; Nurizzo, C

    2013-01-01

    The paper is a review of previous research on secondary effluent disinfection by peracetic acid (PAA) integrated with new data about the effect of a preliminary flash-mixing step. The process was studied at bench and pilot scale to assess its performance for discharge in surface water and agricultural reuse (target microorganisms: Escherichia coli and faecal coliform bacteria). The purposes of the research were: (1) determining PAA decay and disinfection kinetics as a function of operating parameters, (2) evaluating PAA suitability as a disinfectant, (3) assessing long-term disinfection efficiency, (4) investigating disinfected effluent biological toxicity on some aquatic indicator organisms (Vibrio fischeri, Daphnia magna and Selenastrum capricornutum), (5) comparing PAA with conventional disinfectants (sodium hypochlorite, UV irradiation). PAA disinfection was capable of complying with Italian regulations on reuse (10 CFU/100 mL for E. coli) and was competitive with benchmarks. No regrowth phenomena were observed, as long as needed for agricultural reuse (29 h after disinfection), even at negligible concentrations of residual disinfectant. The toxic effect of PAA on the aquatic environment was due to the residual disinfectant in the water, rather than to chemical modification of the effluent.

  20. Preactivated thiomers: Permeation enhancing properties

    PubMed Central

    Wang, Xueqing; Iqbal, Javed; Rahmat, Deni; Bernkop-Schnürch, Andreas

    2012-01-01

    The study was aimed to prepare a series of poly(acrylic acid)-cysteine-2-mercaptonicotinic acid conjugates (preactivated thiomers) and to evaluate the influence of molecular mass or degree of preactivation with 2-mercaptonicotinic acid (2MNA) on their permeation enhancing properties. Preactivated thiomers with different molecular mass and different degree of preactivation were synthesized and categorized on the basis of their molecular mass and degree of preactivation as PAA100-Cys-2MNA (h), PAA250-Cys-2MNA (h), PAA450-Cys-2MNA (h), PAA450-Cys-2MNA (m) and PAA450-Cys-2MNA (l). In vitro permeation studies, the permeation enhancement ability for preactivated thiomers was ranked as PAA450-Cys-2MNA (h) > PAA250-Cys-2MNA (h) > PAA100-Cys-2MNA (h) on both Caco-2 cell monolayers and rat intestinal mucosa. Comparing the influence of degree of preactivation with 2MNA on permeation enhancement, the following order PAA450-Cys-2MNA (h) > PAA450-Cys-2MNA (m) ≈ PAA450-Cys-2MNA (l) on Caco-2 cell monolayers and PAA450-Cys-2MNA (m) > PAA450-Cys-2MNA (h) > PAA450-Cys-2MNA (l) on intestinal mucosa was observed. The Papp of sodium fluorescein was 5.08-fold improved on Caco-2 cell monolayers for PAA450-Cys-2MNA (h) and 2.46-fold improved on intestinal mucosa for PAA450-Cys-2MNA (m), respectively, in comparison to sodium fluorescein in buffer only. These results indicated that preactivated thiomers could be considered as a promising macromolecular permeation enhancing polymer for non-invasive drug administration. PMID:22960503

  1. Biomimetic growth of hydroxyapatite on gelatin films doped with sodium polyacrylate.

    PubMed

    Bigi, A; Boanini, E; Panzavolta, S; Roveri, N

    2000-01-01

    Gelatin films were used as biomimetic substrates for the nucleation of hydroxyapatite from simulated body fluid (SBF). Stretching and presence of sodium polyacrylate appear to be essential factors for the specific nucleation and growth of hydroxyapatite crystals inside the films. After soaking in 1.5SBF for periods longer than 4 days, all the films display a completely calcified surface. However, the spherical aggregates on the film surfaces do not give any X-ray diffraction effect and exhibit a low Ca/P molar ratio, typical of amorphous calcium phosphate. The ordered deposition of crystalline hydroxyapatite has been verified to take place only in stretched polyacrylate--gelatin films. The crystals grow as tablets about 2 microns thick among the gelatin layers, with their crystallographic c-axes preferentially oriented parallel to the direction of orientation of the collagen molecules, thus resembling the parallel orientation of apatitic crystals and collagen fibrils in calcified biological tissues.

  2. Protein partitioning in poly(ethylene glycol)/sodium polyacrylate aqueous two-phase systems.

    PubMed

    Johansson, Hans-Olof; Magaldi, Flavio Musa; Feitosa, Eloi; Pessoa, Adalberto

    2008-01-18

    The partition of hemoglobin, lysozyme and glucose-6-phosphate dehydrogenase (G6PDH) in a novel inexpensive aqueous two-phase system (ATPS) composed by poly(ethylene glycol) (PEG) and sodium polyacrylate (NaPA) has been studied. The effect of NaCl and Na(2)SO(4), pH and PEG molecular size on the partitioning has been studied. At high pH (above 9), hemoglobin partitions strongly to the PEG-phase. Although some precipitation of hemoglobin occurs, high recovery values are obtained particularly for lysozyme and G6PDH. The partitioning forces are dominated by the hydrophobic and electrochemical (salt) effects, since the positively charged lysozyme and negatively charged G6PDH partitions to the non-charged PEG and the strongly negatively charged polyacrylate enriched phase, respectively.

  3. Sodium polyacrylate adsorption onto anionic and cationic silica in the presence of salts.

    PubMed

    Flood, Charlie; Cosgrove, Terence; Espidel, Youssef; Howell, Ian; Revell, Patricia

    2007-05-22

    Sodium polyacrylate is well known for its application as a scale inhibitor in common household products, and the effects of both monovalent and divalent metal cations on its structure have been covered by a range of previous publications. In the present article, we extend this work by using solvent relaxation NMR to look at the adsorption of the polyelectrolyte onto both positively and negatively charged silica and how this is altered by calcium chloride. In the anionic case, we found that polyacrylate adsorption was predictably very weak, and interestingly, perhaps counterintuitively, it was further reduced by calcium ions. This is probably linked to NaPA-Ca2+ binding, which changes the conformation and charge of the polyelectrolyte. In contrast, NaPA adsorbs very strongly on cationic silica, to the point that precipitation often occurs, particularly on addition of salt.

  4. In vivo studies of polyacrylate nanoparticle emulsions for topical and systemic applications.

    PubMed

    Greenhalgh, Kerriann; Turos, Edward

    2009-03-01

    We have recently reported on a new nanomedicine containing antibiotic-conjugated polyacrylate nanoparticles, which has shown activity against methicillin-resistant Staphylococcus aureus (MRSA) in vitro and no cytotoxicity toward human dermal cells. The water-based nanoparticle emulsion is capable of solubilizing lipophilic antibiotics for systemic administration, and the nanoparticle drug delivery vehicle has shown protective properties for antibiotics from hydrolytic cleavage by bacterial penicillinases, thus rejuvenating the drug's activity against resistant microbes such as MRSA. Here we report the first in vivo study of this penicillin-conjugated nanoparticle emulsion in determining toxicological responses initiated upon systemic and topical application in a murine model. Favorable results were observed in vivo upon both routes of administration and, when topically applied to a dermal abrasion model, the emulsion enhanced wound healing by an average of 3 to 5 days. This study suggests that polyacrylate nanoparticle-containing emulsions may afford promising opportunities for treating both skin and systemic infections.

  5. Optical waveguide BTX gas sensor based on polyacrylate resin thin film.

    PubMed

    Kadir, Razak; Yimit, Abliz; Ablat, Hayrensa; Mahmut, Mamtimin; Itoh, Kiminori

    2009-07-01

    An optical sensor sensitive to BTX has been developed by spin coating a thin film of polyacrylate resin onto a tin- diffused glass optical waveguide. A pair of prism coupler was employed for optical coupling matched with diiodomethane (CH2l2). The guided wave transmits in waveguide layer and passes through the film as an evanescent wave. Polyacrylate film has a strong capacity of absorbing oil gases. The film is stable in N2 but benzene exposure at room temperature can result in rapid and reversible changes of transmittance (7) and refractive index (n1) of this film. It has been demonstrated that the sensor containing a 10 mm boardand about a hundred nanometers thick resin film can detect lower than 8 ppm BTX.

  6. Fabrication of polyacrylate core-shell nanoparticles via spray drying method

    NASA Astrophysics Data System (ADS)

    Chen, Pengpeng; Cheng, Zenghui; Chu, Fuxiang; Xu, Yuzhi; Wang, Chunpeng

    2016-05-01

    Fine polyacrylate particles are thought to be environmental plastisols for car industry. However, these particles are mainly dried through demulsification of the latexes, which is not reproducible and hard to be scaled up. In this work, a spray drying method had been applied to the plastisols-used acrylate latex. By adjusting the core/shell ratio, spray drying process of the latex was fully studied. Scanning electronic microscopy observation of the nanoparticles before and after spray drying indicated that the core-shell structures could be well preserved and particles were well separated by spray drying if the shell was thick enough. Otherwise, the particles fused into each other and core-shell structures were destroyed. Polyacrylate plastisols were developed using diisononylphthalate as a plasticizer, and plastigels were obtained after heat treatment of the sols. Results showed that the shell thickness also had a great influence on the storage stability of the plastisols and mechanical properties of the plastigels.

  7. Small Angle Neutron Scattering experiments on ``side-on fixed"" liquid crystal polyacrylates

    NASA Astrophysics Data System (ADS)

    Leroux, N.; Keller, P.; Achard, M. F.; Noirez, L.; Hardouin, F.

    1993-08-01

    Small Angle Neutron Scattering experiments were carried out on liquid crystalline “side-on fixed” polyacrylates : we observe that the polymer backbone adopts a prolate conformation in the nematic phase. Such anisotropy of the global backbone is larger for smaller spacer length. In every case we measure at low temperatures a large chain extension as previously described in polysiloxanes. Par diffusion des neutrons aux petits angles nous observons que la chaîne de polyacrylates “en haltère” adopte une conformation type prolate en phase nématique. Son anisotropie est d'autant plus grande que l'espaceur est plus court. Dans tous les cas, nous retrouvons à basse température la forte extension de la chaîne polymère qui fut d'abord révélée dans les polysiloxanes.

  8. Structural and optical behavior of thin films of protein (BSA)-Polyelectrolyte (PAA, PSS) complexes

    NASA Astrophysics Data System (ADS)

    Talukdar, Hrishikesh; Kundu, Sarathi

    2017-05-01

    Optical behaviors of protein (BSA) in the presence of negatively charged polyelectrolytes (PAA and PSS) in thin film confirmation are studied using UV-Vis and photoluminescence spectroscopy. The out-of-plane structures and in-plane surface morphologies of the thin films of protein-polyelectrolyte complexes (PPC) are investigated using X-ray reflectivity (XRR) and Atomic force microscopy (AFM) respectively. It is found that although the out-of-plane structure and surface morphology of PPC is nearly same as in pure polyelectrolyte but a larger red-shift of ≈ 23 nm is obtained in optical emissions from the thin films of PPC in comparison with that of the pure protein and PPC solutions. Mechanism is proposed for such larger red-shift from the thin film of PPC.

  9. Microfluidic formation of pH responsive 5CB droplets decorated with PAA-b-LCP.

    PubMed

    Khan, Waliullah; Choi, Jin Ho; Kim, Gyu Man; Park, Soo-Young

    2011-10-21

    We are reporting for the first time the pH responsiveness of liquid crystal (LC) microdroplets decorated with an amphiphilic block copolymer of PAA-b-LCP. We successfully demonstrated the adsorption of block copolymer on LC droplets by fluorescence microscopy and pH response to the radial-to-bipolar orientational change of the LC droplets by changing pH from 12 to 2 through the polarized optical microscope (POM). We believe that our results may pave the way for the generation of monodisperse droplets decorated by various amphiphilic block copolymers which respond to several kinds of the external stimuli. These developments may be important for potential applications of the LC droplets in sensing and encapsulation fields.

  10. Use of insoluble polyacrylate polymers to aid phytostabilization of mine soils: effects on plant growth and soil characteristics.

    PubMed

    Qu, G; de Varennes, A; Cunha-Queda, C

    2010-01-01

    We evaluated the use of polyacrylate polymers to aid phytostabilization of mine soils. In a pot experiment, perennial ryegrass was grown in a mine soil and in uncontaminated soil. Growth was stimulated in the polymer-amended mine soil compared with an unamended control, and water-extractable levels of soil Cu and Zn decreased after polymer application. In an experiment performed in six 60-cm-diameter cylinders filled with fertilized mine soil, polymers were applied to three cylinders, with the remainder used as unamended control. Total biomass produced by indigenous plant species sown in polymer-amended soil was 1.8 (Spring-Summer) or 2.4 times (Fall-Winter) greater than that of plants from unamended soil. The application of polymers to the mine soil led to the greatest activity of soil enzymes. Soil pH, biomass of Spergularia purpurea and Chaetopogon fasciculatus, and activities of protease and cellulase had large loadings on principal component (PC)1, whereas growth of Briza maxima and the activities of urease, acid phosphatase, and beta-glucosidase had large loadings on PC2. The treatments corresponding to controls were located on the negative side of PC1 and PC2. Amended treatments were on the positive side of PC2 (Spring-Summer) or on the positive side of PC1 (Fall-Winter), demonstrating differential responses of plants and soil parameters in the two growth cycles.

  11. Controlled formation of ag nanoparticles by means of long-chain sodium polyacrylates in dilute solution.

    PubMed

    Huber, Klaus; Witte, Thomas; Hollmann, Jutta; Keuker-Baumann, Susanne

    2007-02-07

    A new tool is presented to control formation of Ag nanoparticles. Small amounts of silver ions were added to dilute solutions of long-chain sodium polyacrylates (NaPA). Four NaPA samples covering a molar mass regime of 97 kD < or = Mw < or = 650 kD have been used. With amounts of added Ag(+) as low as 1-2% of the COO(-) groups of the polyanionic chains, significant changes could already be induced in the NaPA coils with 650 kD. If the NaPA concentration was kept below 0.1 g/L, the coils with 650 kD exhibited a significant coil shrinking in stable solutions. At larger NaPA concentrations, addition of Ag+ initiates an aggregation of the polyacrylate coils toward compact structures. Coil shrinking and aggregation was revealed by means of time-resolved static light scattering. If exposed to UV-radiation, small Ag particles formed within the shrunken anionic polyacrylate coils. The Ag nanoparticles were identified by means of an enhanced light scattering and a characteristic plasmon absorption band around 410 nm. No such Ag particle formation could be observed even at 5 times larger concentrations of Ag(+) and NaPA if the two smallest polyacrylate samples have been used under otherwise equal conditions. This molar mass sensitive response of NaPA to Ag(+)-addition suggests an interesting phenomenon: if the coil size of the NaPa chains, which act as Ag(+) collectors, is large enough, local Ag(+) concentration in these coil-shaped Ag(+) containers exceeds a critical value, and irradiation with UV generates Ag nanoparticles.

  12. Lowering the resistivity of polyacrylate ion-selective membranes by platinum nanoparticles addition.

    PubMed

    Jaworska, Ewa; Kisiel, Anna; Maksymiuk, Krzysztof; Michalska, Agata

    2011-01-01

    The effect of platinum nanoparticles introduction into polyacrylate membranes was examined. Platinum nanoparticles were added to the membrane cocktail before photopolymerization of the poly(n-butyl acrylate) based ion-selective membranes. Thus obtained sensors were characterized with significantly lowered electrical resistance and increased stability of potential readings compared to classical poly(n-butyl acrylate) membranes. The analytical parameters of platinum nanoparticle containing membranes were well comparable with those of classical membranes.

  13. Flotation of oxidized coal with a latex emulsion of sodium polyacrylate used as a promoter

    SciTech Connect

    Finch, R.E.

    1980-09-16

    A method and treating agent for increasing the yield of oxidized coal or coal from surface or strip mines where said coal particles are concentrated by froth flotation. The method consists of utilizing as a promoter or frothing aid about 05-1.5 lbs of sodium polyacrylate latex per ton of dry coal (0.017-0.5 lb of dry sodium polyacrylate per ton of dry coal), having an average molecular weight of about 100,000 to 1,000,000 and more, with a preferred range of 1,000,000 or more. The preferred promoter or frothing aid for oxidized coal is a water-in-oil latex of sodium polyacrylate and preferably used with an alcohol-type frother. The latex may be utilized neat and self inverts with the assistance of an oil-in-water surfactant hydrophilic (Or activator) and the water in the system upon application to form an oil-in-water emulsion, or it may be used as a two-part system with an activator (Aqueous) to promote inversion. The latex emulsion has demonstrated superiority as a flotation promoter for oxidized coal over the dry polymer and exhibits synergism over the dry polymer and over the components of the latex emulsion including a paraffin solvent, a hydrophobic emulsifier such as sorbitan monooleate, a solvent such as espersol 3-e (Charter; an aromatic blend) and stabilizers such as polyisobutylene and aluminum tristearate.

  14. Structure and Hydrogen Bonding of Water in Polyacrylate Gels: Effects of Polymer Hydrophilicity and Water Concentration.

    PubMed

    Mani, Sriramvignesh; Khabaz, Fardin; Godbole, Rutvik V; Hedden, Ronald C; Khare, Rajesh

    2015-12-10

    The ability to tune the hydrophilicity of polyacrylate copolymers by altering their composition makes these materials attractive candidates for membranes used to separate alcohol-water mixtures. The separation behavior of these polyacrylate membranes is governed by a complex interplay of factors such as water and alcohol concentrations, water structure in the membrane, polymer hydrophilicity, and temperature. We use molecular dynamics simulations to investigate the effect of polymer hydrophilicity and water concentration on the structure and dynamics of water molecules in the polymer matrix. Samples of poly(n-butyl acrylate) (PBA), poly(2-hydroxyethyl acrylate) (PHEA), and a 50/50 copolymer of BA and HEA were synthesized in laboratory, and their properties were measured. Model structures of these systems were validated by comparing the simulated values of their volumetric properties with the experimental values. Molecular simulations of polyacrylate gels swollen in water and ethanol mixtures showed that water exhibits very different affinities toward the different (carbonyl, alkoxy, and hydroxyl) functional groups of the polymers. Water molecules are well dispersed in the system at low concentrations and predominantly form hydrogen bonds with the polymer. However, water forms large clusters at high concentrations along with the predominant formation of water-water hydrogen bonds and the acceleration of hydrogen bond dynamics.

  15. The capture and stabilization of curcumin using hydrophobically modified polyacrylate aggregates and hydrogels.

    PubMed

    Harada, Takaaki; Pham, Duc-Truc; Lincoln, Stephen F; Kee, Tak W

    2014-08-07

    Hydrophobically modified polyacrylates are shown to suppress the degradation of the medicinal pigment curcumin under physiological conditions. In aqueous solution, the 3% octadecyl randomly substituted polyacrylate, PAAC18, forms micelle-like aggregates at a concentration of <1 wt % and a hydrogel at >1 wt %. Under both conditions, PAAC18 shows a remarkable ability to suppress the degradation of curcumin at pH 7.4 and 37 °C such that its degradation half-life is increased by 1600-2000-fold. The suppression of degradation is attributed to hydrophobic interactions between curcumin and the octadecyl substituents of PAAC18 within the micelle-like aggregates and the hydrogel, as indicated by 2D NOESY (1)H NMR spectroscopy. UV-visible absorption titration results are consistent with the interaction of curcumin with five octadecyl substituents on average, which appears to substantially exclude water and greatly decrease the curcumin degradation rate. Dynamic light scattering and zeta potential measurements show the average hydrodynamic diameters of the PAAC18 aggregates to be 0.86-1.15 μm with a negative surface charge. In contrast to the octadecyl substitution, the 3% dodecyl randomly substituted polyacrylate, PAAC12, shows a negligible effect on slowing the degradation of curcumin, consistent with the dodecyl substituents being insufficiently long to capture curcumin in a adequately hydrophobic environment. These observations indicate the potential for PAAC18 to act as a model drug delivery system.

  16. Effect of Water Concentration on the Molecular Structure of Polyacrylate Gels

    NASA Astrophysics Data System (ADS)

    Mani, Sriramvignesh; Khabaz, Fardin; Khare, Rajesh

    2015-03-01

    Recent studies have suggested pervaporation to be a promising alternative method for separation of aqueous solution of alcohol compared to distillation based separation processes. The ability to tune the hydrophobic/hydrophilic character makes polyacrylate gels attractive candidate materials for separating water-alcohol mixture by pervaporation. Experimentally, it is observed that the amount of water absorbed in the gel i.e. the degree of swelling of the gel shows a large variation with polymer chemistry. Relatively few studies exist highlighting the effects of water concentration on the membrane separation efficiency which in turn is directly related to the internal molecular structure of the water rich membranes. In this regard, an all-atom molecular dynamics (MD) simulation is employed to study water structure in polyacrylate gels. As a first step, polyacrylate copolymer systems with varying degree of hydrophobicity are prepared using the simulated annealing polymerization technique. Atomistic structures of gels containing different amounts of water are also prepared. Effect of water content on the acrylate-water system microstructure is determined by characterizing the packing of water molecules as well as the hydrogen bonding in these systems. In addition, the change in dynamics of water molecules due to the interactions with polymer is captured by monitoring the auto-correlation function of their dipole vector.

  17. Template directed reactions of 2-aminoadenylic acid derivatives

    NASA Technical Reports Server (NTRS)

    Webb, T. R.; Orgel, L. E.

    1982-01-01

    The template-directed oligomerization of activated derivatives of 2-aminoadenylic acid (paA) on polyuridylic acid (poly(U)) in aqueous buffers was studied. The reaction differs from that of adenylic acid (pA) under identical conditions, in that only di- and tri-nucleotides are observed as substantial products rather than a longer sequence of oligomers. The reaction of paA also differs from that of pA in that it does not require Mg (2+), and is less susceptible to increased temperature. The relevance of these observations to the chemical evolution of polynucleotide replication is discussed. Improved syntheses of paA and its diphosphate are reported.

  18. Template directed reactions of 2-aminoadenylic acid derivatives

    NASA Technical Reports Server (NTRS)

    Webb, T. R.; Orgel, L. E.

    1982-01-01

    The template-directed oligomerization of activated derivatives of 2-aminoadenylic acid (paA) on polyuridylic acid (poly(U)) in aqueous buffers was studied. The reaction differs from that of adenylic acid (pA) under identical conditions, in that only di- and tri-nucleotides are observed as substantial products rather than a longer sequence of oligomers. The reaction of paA also differs from that of pA in that it does not require Mg (2+), and is less susceptible to increased temperature. The relevance of these observations to the chemical evolution of polynucleotide replication is discussed. Improved syntheses of paA and its diphosphate are reported.

  19. Poly(vinylidene fluoride) polymer based nanocomposites with enhanced energy density by filling with polyacrylate elastomers and BaTiO3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, Ke; Bai, Yuanyuan; Zhou, Yongcun; Niu, Yujuan; Wang, Hong

    2014-02-01

    Polyacrylate elastomers were introduced into poly(vinylidene fluoride) polymer-based nanocomposites filled with BaTiO3 nanoparticles and the three-phase nanocomposite films were prepared. The energy discharged of the nanocomposite with 3 vol. % polyacrylate elastomers is 8.8 J/cm3, approximately 11% higher compared to that of the nanocomposite without adding polyacrylate elastomers. Large elastic deformation of the polyacrylate elastomers increases Maxwell-Wagner-Sillars interfacial polarization and space charge polarization of the nanocomposites with the electric field increasing, which results in increased maximum polarization and energy discharged of the nanocomposites.

  20. The effects of the thiolation with thioglycolic acid and l-cysteine on the mucoadhesion properties of the starch-graft-poly(acrylic acid).

    PubMed

    Gök, M Koray; Demir, Kamber; Cevher, Erdal; Özsoy, Yıldız; Cirit, Ümüt; Bacınoğlu, Süleyman; Özgümüş, Saadet; Pabuccuoğlu, Serhat

    2017-05-01

    The aim of this study is to investigate the effects of the thiolation on the mucoadhesion characteristics of the gelatinized and crosslinked wheat starch-graft-poly(acrylic acid) [(WS-g-PAA)gc] for potential use in drug delivery via vaginal route. Thiolation of (WS-g-PAA)gc was first time realized using l-cysteine hydrochloride monohydrate (CyS) and thioglycolic acid (TGA). These conjugates [(WS-g-PAA)gcth] were characterized using FTIR. The free SH group, mucoadhesion, cytotoxicity characteristics and the mechanism of the thiolation were also evaluated. To obtain fundamental data for possible application such as drug carrier, in vitro and in vivo progesterone release profiles from the mucoadhesive tablet formulations were also determined. The results showed that, vaginal tablet containing (WS-g-PAA)gc-TGA, which has not contain free SH groups in its structure, displays higher mucoadhesion than (WS-g-PAA)gc and (WS-g-PAA)gc-CyS. This tablet formulation can also be used as a drug carrier in vaginal applications.

  1. Composite poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/collagen nanofibrous scaffolds for dermal tissue regeneration.

    PubMed

    Ravichandran, Rajeswari; Venugopal, Jayarama Reddy; Sundarrajan, Subramanian; Mukherjee, Shayanti; Sridhar, Radhakrishnan; Ramakrishna, Seeram

    2012-08-01

    Tissue engineering scaffolds for skin tissue regeneration is an ever expounding area of research, as the products that meet the necessary requirements are far and elite. The nanofibrous poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/Collagen (PLLA/PAA/Col I&III) scaffolds were fabricated by electrospinning and characterized by SEM, contact angle and FTIR analysis for skin tissue regeneration. The cell-scaffold interactions were analyzed by cell proliferation and their morphology observed in SEM. The results showed that the cell proliferation was significantly increased (p≤0.05) in PLLA/PAA/Col I&III scaffolds compared to PLLA and PLLA/PAA nanofibrous scaffolds. The abundance and accessibility of adipose derived stem cells (ADSCs) may prove to be novel cell therapeutics for dermal tissue regeneration. The differentiation of ADSCs was confirmed using collagen expression and their morphology by CMFDA dye extrusion technique. The current study focuses on the application of PLLA/PAA/Col I&III nanofibrous scaffolds for skin tissue engineering and their potential use as substrate for the culture and differentiation of ADSCs. The objective for inclusion of a novel cell binding moiety like PAA was to replace damaged extracellular matrix and to guide new cells directly into the wound bed with enhanced proliferation and overall organization. This combinatorial epitome of PLLA/PAA/Col I&III nanofibrous scaffold with stem cell therapy to induce the necessary paracrine signalling effect would favour faster regeneration of the damaged skin tissues.

  2. Modulation of the phenylacetic acid metabolic complex by quinic acid alters the disease-causing activity of Rhizoctonia solani on tomato.

    PubMed

    Bartz, Faith E; Glassbrook, Norman J; Danehower, David A; Cubeta, Marc A

    2013-05-01

    The metabolic control of plant growth regulator production by the plant pathogenic fungus Rhizoctonia solani Kühn (teleomorph=Thanatephorus cucumeris (A.B. Frank) Donk) and consequences associated with the parasitic and saprobic activity of the fungus were investigated. Fourteen genetically distinct isolates of the fungus belonging to anastomosis groups (AG) AG-3, AG-4, and AG-1-IA were grown on Vogel's minimal medium N with and without the addition of a 25 mM quinic acid (QA) source of carbon. The effect of QA on fungal biomass was determined by measuring the dry wt of mycelia produced under each growth condition. QA stimulated growth of 13 of 14 isolates of R. solani examined. The production of phenylacetic acid (PAA) and the chemically related derivatives 2-hydroxy-PAA, 3-hydroxy-PAA, 4-hydroxy-PAA, and 3-methoxy-PAA on the two different media was compared by gas chromatography coupled with mass spectrometry (GC-MS). The presence of QA in the growth medium of R. solani altered the PAA production profile, limiting the conversion of PAA to derivative forms. The effect of QA on the ability of R. solani to cause disease was examined by inoculating tomato (Solanum lycopersicum L.) plants with 11 isolates of R. solani AG-3 grown on media with and without the addition of 25 mM QA. Mean percent survival of tomato plants inoculated with R. solani was significantly higher when the fungal inoculum was generated on growth medium containing QA. The results of this study support the hypotheses that utilization of QA by R. solani leads to reduced production of the plant growth regulators belonging to the PAA metabolic complex which can suppress plant disease development.

  3. Effect of peracetic acid on biofilms formed by Staphylococcus aureus and Listeria monocytogenes isolated from dairy plants.

    PubMed

    Lee, S H I; Cappato, L P; Corassin, C H; Cruz, A G; Oliveira, C A F

    2016-03-01

    This research investigated the removal of adherent cells of 4 strains of Staphylococcus aureus and 1 Listeria monocytogenes strain (previously isolated from dairy plants) from polystyrene microtiter plates using peracetic acid (PAA, 0.5%) for 15, 30, 60, and 120 s, and the inactivation of biofilms formed by those strains on stainless steel coupons using the same treatment times. In the microtiter plates, PAA removed all S. aureus at 15 s compared with control (no PAA treatment). However, L. monocytogenes biofilm was not affected by any PAA treatment. On the stainless steel surface, epifluorescence microscopy using LIVE/DEAD staining (BacLight, Molecular Probes/Thermo Fisher Scientific, Eugene, OR) showed that all strains were damaged within 15 s, with almost 100% of cells inactivated after 30 s. Results of this trial indicate that, although PAA was able to inactivate both S. aureus and L. monocytogenes monospecies biofilms on stainless steel, it was only able to remove adherent cells of S. aureus from polystyrene microplates. The correct use of PAA is critical for eliminating biofilms formed by S. aureus strains found in dairy plants, although further studies are necessary to determine the optimal PAA treatment for removing biofilms of L. monocytogenes.

  4. [Disinfection efficiency of peracetic acid, alone and in combination with hypochlorite, against Mycobacterium avium in drinking water].

    PubMed

    Schiavano, G F; Sisti, M; De Santi, M; Brandi, G

    2006-01-01

    Peracetic acid (PAA) is a disinfectant with a wide spectrum of antimicrobial activity, but little is known about the feasibility of using it in the field of drinking water treatment. The aim of this study has been assess disinfectant efficacy of PAA, alone or in combination with hypochlorite, against M. avium in drinking water M. avium is a common opportunistic pathogen in immunocompromised subjects that is able to survive and grow in drinking water distribution systems. In this study PAA did not show appreciable activity against the greater number of tested strains (16/21) up to 5 ppm of PAA, a weak activity was seen on 4 strains, while a significant reduction in viable cells (about 50%) was seen only on 1 strain after 48 h of treatment with 5 ppm of PAA. We also evidenced that M. avium was unaffected by chlorine concentration usually present in drinking water distribution system. Finally, the combination of PAA and sodium hypochlorite did not promote enhanced antimicrobial efficacy respect to the single disinfectants. In conclusion, our result would indicate that PAA is an unlikely candidate for the disinfection of drinking water from M. avium and further strategies are required to eliminate M. avium from drinking water system.

  5. Phenylacetic acid co-crystals with acridine, caffeine, isonicotinamide and nicotinamide: Crystal structures, thermal analysis, FTIR spectroscopy and Hirshfeld surface analysis

    NASA Astrophysics Data System (ADS)

    Amombo Noa, Francoise M.; Jacobs, Ayesha

    2017-07-01

    Co-crystals of phenylacetic acid (PAA) with acridine (ACR), caffeine (CAF), isonicotinamide (INM) and nicotinamide (NAM) have been successfully prepared and characterised by single crystal X-ray diffraction, FTIR spectroscopy, thermal analysis and Hirshfeld surface analysis. The ACR, INM and NAM co-crystals with PAA exhibit the carboxylic acid-pyridine heterosynthon. Furthermore the amide-amide supramolecular homosynthon is observed in the PAA co-crystals with INM and NAM as well as Nsbnd H⋯O interactions between the acid and the respective base. The CAF co-crystal exhibits hydrogen bonding between the imidazole nitrogen and the COOH group of the PAA. The compounds demonstrate different stoichiometries; for PAA·ACR and PAA·INM a 1:1 ratio is displayed, a 2:1 in 2PAA·CAF and a 2:2 in the case of 2PAA·2NAM.

  6. Phenylacetic and phenylpropionic acids do not affect xylan degradation by Ruminococcus albus.

    PubMed

    Reveneau, Carine; Adams, Sarah E; Cotta, M A; Morrison, M

    2003-11-01

    Since the addition of either ruminal fluid or a combination of phenylacetic and phenylpropionic acids (PAA/PPA) has previously been shown to dramatically improve cellulose degradation and growth of Ruminococcus albus, it was of interest to determine the effects of these additives on xylan-grown cultures. Although cell-bound xylanase activity increased when either PAA/PPA or ruminal fluid was added to the growth medium, total xylanase did not change, and neither of these supplements affected the growth or xylan-degrading capacity of R. albus 8. Similarly, neither PAA/PPA nor ruminal fluid affected xylan degradation by multiple strains of R. albus when xylan prepared from oat spelts was used as a carbohydrate source. These results show that the xylanolytic potential of R. albus is not conditional on the availability of PAA/PPA or other components of ruminal fluid.

  7. Phenylacetic and Phenylpropionic Acids Do Not Affect Xylan Degradation by Ruminococcus albus

    PubMed Central

    Reveneau, Carine; Adams, Sarah E.; Cotta, M. A.; Morrison, M.

    2003-01-01

    Since the addition of either ruminal fluid or a combination of phenylacetic and phenylpropionic acids (PAA/PPA) has previously been shown to dramatically improve cellulose degradation and growth of Ruminococcus albus, it was of interest to determine the effects of these additives on xylan-grown cultures. Although cell-bound xylanase activity increased when either PAA/PPA or ruminal fluid was added to the growth medium, total xylanase did not change, and neither of these supplements affected the growth or xylan-degrading capacity of R. albus 8. Similarly, neither PAA/PPA nor ruminal fluid affected xylan degradation by multiple strains of R. albus when xylan prepared from oat spelts was used as a carbohydrate source. These results show that the xylanolytic potential of R. albus is not conditional on the availability of PAA/PPA or other components of ruminal fluid. PMID:14602663

  8. The PaaX Repressor, a Link between Penicillin G Acylase and the Phenylacetyl-Coenzyme A Catabolon of Escherichia coli W

    PubMed Central

    Galán, Beatriz; García, José L.; Prieto, María A.

    2004-01-01

    The pac gene, encoding the penicillin G acylase from Escherichia coli W, is regulated by the PaaX repressor of the phenylacetate catabolic pathway. pac expression depends on the synthesis of phenylacetyl-coenzyme A. PaaX and the cyclic AMP receptor protein (CRP) bind in vitro to the Ppac promoter region. A palindromic sequence proposed as the PaaX operator is located upstream of the −35 box overlapping a CRP binding site, an unusual position that suggests a novel regulatory mechanism. PMID:15028709

  9. Using peracetic acid to control fungus on catfish eggs

    USDA-ARS?s Scientific Manuscript database

    A promising new treatment for parasites and egg fungi is peracetic acid (PAA; also called peroxyacetic acid). It is registered with the U.S. Environmental Protection Agency (EPA) as an oxidizing agent used as an antimicrobial compound approved for indoor use on hard, non-porous surfaces. This stud...

  10. Blends and Iodine complexes of starch with other water-soluble polymers

    USDA-ARS?s Scientific Manuscript database

    In this work, we studied the viscosity and gel formation in the tri-component system, starch/poly(acrylic acid) (PAA), poly(N-vinyl pyrrolidone) (PVP). Starch and poly(acrylic acid) at 5% aqueous solution formed a synergistic mixture at 60/40 ratio. The addition of a small amount of PVP caused the...

  11. Mechanism of Sporicidal Activity for the Synergistic Combination of Peracetic Acid and Hydrogen Peroxide.

    PubMed

    Leggett, Mark J; Schwarz, J Spencer; Burke, Peter A; McDonnell, Gerald; Denyer, Stephen P; Maillard, Jean-Yves

    2015-12-04

    There is still great interest in controlling bacterial endospores. The use of chemical disinfectants and, notably, oxidizing agents to sterilize medical devices is increasing. With this in mind, hydrogen peroxide (H2O2) and peracetic acid (PAA) have been used in combination, but until now there has been no explanation for the observed increase in sporicidal activity. This study provides information on the mechanism of synergistic interaction of PAA and H2O2 against bacterial spores. We performed investigations of the efficacies of different combinations, including pretreatments with the two oxidizers, against wild-type spores and a range of spore mutants deficient in the spore coat or small acid-soluble spore proteins. The concentrations of the two biocides were also measured in the reaction vessels, enabling the assessment of any shift from H2O2 to PAA formation. This study confirmed the synergistic activity of the combination of H2O2 and PAA. However, we observed that the sporicidal activity of the combination is largely due to PAA and not H2O2. Furthermore, we observed that the synergistic combination was based on H2O2 compromising the spore coat, which was the main spore resistance factor, likely allowing better penetration of PAA and resulting in the increased sporicidal activity.

  12. Mechanism of Sporicidal Activity for the Synergistic Combination of Peracetic Acid and Hydrogen Peroxide

    PubMed Central

    Leggett, Mark J.; Schwarz, J. Spencer; Burke, Peter A.; McDonnell, Gerald; Denyer, Stephen P.

    2015-01-01

    There is still great interest in controlling bacterial endospores. The use of chemical disinfectants and, notably, oxidizing agents to sterilize medical devices is increasing. With this in mind, hydrogen peroxide (H2O2) and peracetic acid (PAA) have been used in combination, but until now there has been no explanation for the observed increase in sporicidal activity. This study provides information on the mechanism of synergistic interaction of PAA and H2O2 against bacterial spores. We performed investigations of the efficacies of different combinations, including pretreatments with the two oxidizers, against wild-type spores and a range of spore mutants deficient in the spore coat or small acid-soluble spore proteins. The concentrations of the two biocides were also measured in the reaction vessels, enabling the assessment of any shift from H2O2 to PAA formation. This study confirmed the synergistic activity of the combination of H2O2 and PAA. However, we observed that the sporicidal activity of the combination is largely due to PAA and not H2O2. Furthermore, we observed that the synergistic combination was based on H2O2 compromising the spore coat, which was the main spore resistance factor, likely allowing better penetration of PAA and resulting in the increased sporicidal activity. PMID:26637595

  13. Synthesis of TiO{sub 2} nanoparticles by self-assembling reverse micelle cores of PS-b-PAA for functional textile applications

    SciTech Connect

    Akpolat, Leyla Budama; Çakır, Burçin Acar; Topel, Önder Hoda, Numan

    2015-04-15

    Highlights: • TiO{sub 2} nanoparticles were synthesized within poly(styrene)-b-poly(acrylic acid) micelles. • The copolymer solution including nano TiO{sub 2} was coated onto textile fabrics. • UV-protective factor of nano TiO{sub 2} coated fabrics was estimated as 50+. • Nano TiO{sub 2} coated fabrics was found to exhibit a high photocatalytic activity. - Abstract: Titanium dioxide (i.e., titanium(IV) oxide, TiO{sub 2}) nanoparticles have been fabricated using a copolymer templating technique in micellar solution of poly(styrene)-block-poly(acrylic acid), PS(10912)-b-PAA(4842) synthesized by atom transfer radical polymerization (ATRP). The size and morphology of the synthesized TiO{sub 2} nanoparticles have been characterized via TEM and XRD measurements. The average size of TiO{sub 2} nanoparticles was determined as 13 ± 3 and 13 ± 4 nm for titanium:copolymer ratios of 20:1 and 33:1, respectively. The copolymer solution including nano TiO{sub 2} particles has been coated onto textile fabrics to enhance their UV-blocking and self-cleaning properties. It has been determined that nano TiO{sub 2} coated textile fabrics have very good UV-blocking properties with 50+ of the ultraviolet protecting factor (UPF) and high photocatalytic efficiency with 69.2% of the photodegradation of methylene blue.

  14. Fabrication of macroporous films with closed honeycomb-like pores from exponentially growing layer-by-layer assembled polyelectrolyte multilayers.

    PubMed

    Chen, Xiaoling; Sun, Junqi

    2014-08-01

    We report an innovative method for the fabrication of macroporous films with closed honeycomb-like pores of several micrometers by post-treatment of micrometer-thick poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) films. The precursor PAA/PAH films are fabricated by exponential layer-by-layer assembly of PAA and PAH, which produces PAA/PAH films with highly interpenetrated structures. We disclose that the high mobility of PAA and PAH, which originates from the highly interpenetrated film structures, allows a large-scale phase separation to take place upon post-treatment to produce micrometer-sized honeycomb pores. These macroporous PAA/PAH films can be conveniently released from substrates to produce free-standing films with satisfactory mechanical stability.

  15. Targeted Release of Tobramycin from a pH-Responsive Grafted Bilayer Challenged with S. aureus

    PubMed Central

    Lee, Hyun-Su; Dastgheyb, Sana S.; Hickok, Noreen J.; Eckmann, David M.; Composto, Russell J.

    2015-01-01

    A stimuli-responsive, controlled release bilayer for the prevention of bacterial infection on biomaterials is presented. Drug release is locally controlled by the pH-responsiveness of the bilayer, comprised of an inner poly(acrylic acid) (PAA) monolayer grafted to a biomaterial and cross-linked with an outer chitosan (CH) brush. Tobramycin (TOB) is loaded in the inner PAA in part to minimize bacteria resistance. Because biofilm formation causes a decrease in loc